Hefei, China

Hefei University of Technology is a major university in China, with particular strength in Engineering and Management Science. It is located in Hefei, the capital of the Anhui Province.Hefei University of Technology is a national key university administrated directly by the Ministry of Education. It has been listed in major national initiatives seeking to enhance the international competitiveness of the top-tier universities in China such as Project 211 and Project 985 Innovation Platform.Since its founding in 1945, it has been committed to cultivating talent with excellence, advancing science and technology, pushing social development, and promoting culture, with the spirit best manifested in the university motto "pursuing virtue and knowledge, seeking truth and innovation".HFUT has four campuses – Tunxilu, Lu'anlu, Feicuihu and Xuancheng – covering an area of about 3,417,390 m². The first three campuses are located in Hefei, the provincial capital of Anhui, and the fourth is in Xuancheng, a city about 194 kilometers away from Hefei.Campuses in Hefei have 19 schools covering a wide range of fields with a strong focus on engineering science. The schools offer 82 undergraduate programs, 32 first-level disciplines with authorization to confer master degrees, 12 first-level disciplines for doctoral programs as well as 12 post-doctoral programs. 4 disciplines are selected as national key disciplines and 28 are provincial key disciplines. The university has 1 state key lab, 1 national engineering lab, 4 national university-industry joint engineering research centers and 46 research centers at the ministerial or provincial level as well as 1 national A-level architectural design and research institute. The campus in Xuancheng has 5 departments.The university has a high-level faculty team consisting of 1,824 full-time teachers, among whom 33 enjoy special government allowances of the State Council in recognition of outstanding achievements in their fields. It also boasts 1 academician of the Chinese Academy of Engineering, 8 distinguished experts of the national Thousand Talents Program, 6 accredited professors and 7 chair professors of Yangtze Scholar Program, 5 granted with funds from the National Outstanding Youth Science Foundation, 1 member of Disciplinary Appraisal Panel of the State Council, 1 member of Academic Degrees Committee of the State Council, 10 winners of the national awards for top teachers, etc. The efforts of the dedicated faculty empower the advancement of the university. At present, HFUT enrolls 29,480 undergraduate students and 11,800 graduate students. It has made remarkable achievements in student education. Throughout the years, key disciplines, courses, textbooks, teaching and experiment centers, teaching staff of HFUT have won numerous awards at all levels, highly reputed in China. It is among the first batch of 61 pilot colleges and universities to conduct the Education and Development Plan for Outstanding Engineers initiated by the Ministry of Education. About 200 projects carried out by HFUT students have been funded by the National University Student Innovation Program. HFUT is dedicated to educating its graduates to become innovative engineering talents with professional proficiency, positive working attitude and entrepreneurship.HFUT sticks to innovation and the integration of teaching, research and production. It has a long-established, application-oriented research culture, and it is keen to support the academics in conducting research that has impact and practical value. It is committed to promoting the development of regional economy by catering to the strategic objectives and needs of the industries, the community and the nation. In 2013, the university has an annual research funding in science of over RMB 447 million. The applications for invention patents total 357, of which 204 are licensed; besides, 82 computer software patents are granted. In recent years, HFUT has won 5 national science-and-technology-related awards, and 19 first prizes at the ministerial or provincial level.HFUT is actively pursuing connections with leading institutions through academic partnerships with top universities worldwide. By supporting a wide range of collaborative activities including faculty and student exchange projects, joint supervision plan and international programs at all levels, HFUT has established academic links with more than 30 prestigious universities around the world, such as Ohio State University in U.S.A. Meanwhile, hundreds of international students from over 30 countries and regions are studying at HFUT.Hefei University of Technology, with its 70-year achievements in several key disciplines, is now striving for even greater success with the ultimate goal of becoming a top innovative university with international prestige and distinctive features. Wikipedia.

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Shi D.-M.,Bohai University | Wang B.-H.,Hefei University of Technology
Physica A: Statistical Mechanics and its Applications | Year: 2017

In this study, the enhancing parameter represented the value of the public goods to the public in public goods game, and was rescaled to a Fermi–Dirac distribution function of critical mass. Public goods were divided into two categories, consumable and reusable public goods, and their coevolution with cooperative behavior was studied. We observed that for both types of public goods, cooperation was promoted as the enhancing parameter increased when the value of critical mass was not very large. An optimal value of critical mass which led to the best cooperation was identified. We also found that cooperations emerged earlier for reusable public goods, and defections became extinct earlier for the consumable public goods. Moreover, we observed that a moderate depreciation rate for public goods resulted in an optimal cooperation, and this range became wider as the enhancing parameter increased. The noise influence on cooperation was studied, and it was shown that cooperation density varied non-monotonically as noise amplitude increased for reusable public goods, whereas decreased monotonically for consumable public goods. Furthermore, existence of the optimal critical mass was also identified in other three regular networks. Finally, simulation results were utilized to analyze the provision of public goods in detail. © 2017 Elsevier B.V.

Li J.-H.,Hefei University of Technology
Chinese Journal of Chemical Physics | Year: 2017

Pyoverdine is one of the siderphores excreted by Pseudomonas aeruginosa that can help microbe to uptake iron in vitro. To determine the effect of pyoverdine chelating with iron, we purified the free pyoverdine and applied the dynamic laser light scattering (DLS) to detect the interaction between the pyoverdine and ferric hydroxide. The real-time DLS data analysis indicated that pyoverdine can directly combine with Fe(OH)3 to form complexes and these substances are gradually degraded by themselves then completely disappeared. In our experiment, we have demonstrated that pyoverdine may not only chelate ferric ion but also availably dissolve ferric hydroxide which assists bacteria to survive in iron-deficient environments. © 2017 Chinese Physical Society.

Wu J.,Hefei University of Technology | Wang X.-B.,Hefei University of Technology | Zeng R.J.,Hefei University of Technology
Journal of Hazardous Materials | Year: 2017

The widespread distribution of chromium(VI) in the environment leads to groundwater contamination. The use of iron sulfide (FeS) to remove Cr(VI) has therefore been proposed. However, aggregation is one of the main problems associated with the use of FeS nanoparticles prepared by traditional methods In this study, we used sodium alginate (SA) to stabilize FeS nanoparticles (FeS-SA). SA could prevent aggregation of FeS by the concurrent electrostatic repulsion and steric hindrance. Homogeneously dispersed FeS-SA nanoparticles 100 nm in diameter were observed. FeS-SA showed high efficiency in Cr(VI) removal, corresponding to an enhancement of efficiency from 65% (7.50 mmol Cr(VI) per g FeS) to 100% (11.54 mmol Cr per g FeS) relative to that achieved with naked FeS. Analysis of reaction products by X-ray diffraction and X-ray photoelectron spectroscopy revealed the co-existence of α-FeOOH, S8, and Cr(OH)3 that apparently were introduced by Fe(II), S(−II), and Cr(VI), respectively. In-depth analysis of the removal mechanism revealed that reduction and adsorption respectively account for 82% and 18% of the Cr removal. In addition, higher pH and CaCl2 concentration resulted in lower removal efficiency. This study provides a promising application of SA in enhancing FeS reactivity for the remediation of groundwater pollution. © 2017 Elsevier B.V.

Keshtegar B.,University of Zabol | Meng Z.,Hefei University of Technology
Structural Safety | Year: 2017

The Hasofer-Lind and Rakwitz-Fiessler (HL-RF) algorithm is widely used for structural reliability analysis in first-order moment method (FORM). However, it meets non-convergence problem including generating periodic and chaotic solutions for highly nonlinear limit state function. In this paper, relaxed HL-RF (RHL-RF) is developed based on a relaxed factor, which is dynamically computed by the second-order interpolation between zero and one. A hybrid relaxed HL-RF (HRHL-RF) method is proposed, in which the HL-RF and RHL-RF are adaptively implemented by using an angle criterion to improve the robustness and efficiency of FORM formula. The angle condition is simply calculated based on the results from the new and previous points. Finally, the performances in terms of robustness and efficiency of the HRHL-RF are compared with several existing FORM methods through five mathematical and structural examples. The results indicate that HRHL-RF method is more robust than the HL-RF and more efficient than other existing methods. © 2017 Elsevier Ltd

Xu D.,Nanjing University of Science and Technology | Chen Z.,University of Newcastle | Wang X.,Hefei University of Technology
Automatica | Year: 2017

The authors consider a global robust asymptotic stabilization problem (GRS) for cascaded systems having dynamic uncertainties that are not necessarily input-to-state stable (ISS). Specifically, a recursive Lyapunov design approach is developed by induction on the system relative degree, providing a smoothly globally stabilizing controller. It is applicable to nonlinear cascaded systems having multiple distinct iISS dynamic uncertainties. The proposed design is constructive and leads to an iISS-Lyapunov characterization in a superposition form for the closed-loop system. © 2017 Elsevier Ltd

Zhou W.-B.,Central South University | Yan W.-J.,Hefei University of Technology
Thin-Walled Structures | Year: 2017

In this study, a refined nonlinear finite-element (FE) model of steel-concrete composite beam (SCCB) capable of accommodating various effects such as the initial geometric imperfection, residual stress, interface slip, geometric nonlinearity, and material nonlinearity is developed to study the distortional instability of SCCBs under negative bending moment. The accuracy of the model is validated by publicly available results previously observed by experiments. On the basis of the refined nonlinear FE model, the ultimate bending moment of 54 groups of SCCBs with varying cross-section parameters is calculated. Also, the effects of the force ratio of the SCCB, width–thickness ratio of the compression flange, shear connection degree, and height–thickness ratio of the web on the ultimate bending moment stability coefficient of SCCB in negative bending moment area are investigated in detail. Results show that the effect of the degree of shear connection on the stability coefficient of the SCCB is insignificant, while the stability coefficient decreases with the increase of the remaining parameters, among which the effect of the height–thickness ratio of the web is proven to be the most significant. Finally, considering various effects aforementioned properly, practical formulas are proposed to compute slenderness ratio and ultimate bending moment stability coefficient of SCCB in a concise form, which are shown to be consistent with the FE modelling and experimental results, and thus are suitable for engineering design. © 2017 Elsevier Ltd

Li Y.,Hefei University of Technology | Tao D.,University of Technology, Sydney
IEEE International Conference on Data Mining Workshops, ICDMW | Year: 2017

Given several related tasks, multi-Task learning can improve the performance of each task through sharing parameters or feature representations. In this paper, we apply multi-Task learning to a particular case of distance metric learning, in which we have a small amount of labeled data. Consider the effectiveness of semi-supervised learning handling few labeled machine learning problems, we integrate semi-supervised learning with multi-Task learning and distance metric learning. One of the defect of multi-Task learning is its low training efficiency, as we need all the training examples from all tasks to train a model. We propose an online learning algorithm to overcome this drawback of multi-Task learning. Experiments are conducted on one landmark multi-Task learning dataset to demonstrate the efficiency and effectiveness of our online semi-supervised multi-Task learning algorithm. © 2016 IEEE.

Dai F.-Q.,Hefei University of Technology | Zhao Z.-F.,Hefei University of Technology | Zheng Y.-F.,Hefei University of Technology
Chemical Geology | Year: 2017

Alkaline igneous rocks are a minor component in common associations of felsic to mafic rocks. Although they are usually regarded as the product of mantle-derived magmatism, they are possibly produced by partial melting of the overthickened orogenic crust. This is illustrated by post-collisional alkaline volcanics from the Dabie orogen in China. A combined study of whole-rock major and trace elements and Sr-Nd-Hf isotopes, and zircon U-Pb ages and Hf-O isotopes for these volcanics provides geochemical constraints on the nature of their magma sources and thus insights into reworking of the lower continental crust in a collisional orogen. SIMS zircon U-Pb dating yields consistent Early Cretaceous ages of 136 ± 2 Ma and 133 ± 2 Ma for magma emplacement, contemporaneous with early-stage adakitic rocks in the Dabie orogen. Relict zircons record Neoproterozoic and Triassic U-Pb ages, respectively, in agreement with ages for protolith formation and ultrahigh-pressure metamorphism in the orogen. The alkaline volcanics are composed of phonolite and trachyte, with variable contents of SiO2 (55.94–64.10 wt%), MgO (0.16–0.95 wt%), Al2O3 (16.80–21.32 wt%), K2O (4.65–14.55 wt%) and Na2O + K2O (11.51–15.01 wt%). They show arc-like trace element distribution patterns, with enrichment in LILE and LREE but depletion in HFSE. They exhibit enriched whole-rock Sr-Nd-Hf isotope compositions, with generally high (87Sr/86Sr)i ratios of 0.7074 to 0.7104, but negative εNd(t) values of − 16.3 to − 15.1 and negative εHf(t) values of − 18.4 to − 16.3. Zircon Hf-O isotope analyses yield less variable εHf(t) values of − 27.8 to − 23.0 and δ18O values of 4.9 to 5.9‰ for magmatic zircons, but more variable εHf(t) values of − 32.7 to − 6.5 and δ18O values of 3.0 to 10.2‰ for Neoproterozoic and Triassic relict zircons. Such geochemical features indicate that these alkaline volcanics were derived from partial melting of the subducted continental crust of the South China Block in the Dabie orogen. The magma sources would be dominated by the mafic igneous rocks of middle Neoproterozoic age. Additional contributions were from supracrustal rocks with high δ18O and variable εHf(t) values, which were incorporated into the overthickened orogenic crust during the Triassic continental collision. The orogenic crust underwent low-degree partial melting during its thinning at the post-collisional stage, giving rise to the alkaline volcanics in the Early Cretaceous. © 2017 Elsevier B.V.

Wang M.,Anhui Agricultural University | Zhang R.,Xiamen University of Technology | Zhu X.,Hefei University of Technology
Computers and Industrial Engineering | Year: 2017

This paper focuses on a multi-product vendor-buyer supply chain considering environmental factors in the product manufacturing process. We assume that the unit price charged by the buyer, the unit advertising expenditure and the vendor's unit environmental improvement influence the demand of the product being sold. The relationship between the vendor and the buyer is modeled by a non-cooperative game based on Stackelberg strategy framework under two power scenarios including vendor-leader model and buyer-leader model. A bi-level programming approach is applied to determine the optimal selling prices, advertising expenditures, wholesale prices, vendor's environmental improvements and ordering policies of the vendor and the buyer. Then, a modified differential evolution algorithm is proposed for solving the models. Numerical experiments carried out in this paper, including sensitivity analysis for some key parameters, evaluate the effectiveness of the models and compare the results between the different models considered. Several research findings have been obtained and explained. © 2017 Elsevier Ltd

Chen Y.,Hefei University of Technology | Fu Y.,Hefei University of Technology | Fu Y.,Chinese Academy of Meteorological Sciences
Journal of Applied Meteorology and Climatology | Year: 2017

Many data-merging studies of the Tropical Rainfall Measuring Mission (TRMM) satellite involve the integration of high-resolution Visible and Infrared Scanner (VIRS) signals (~2 km) with low-resolution Precipitation Radar (PR) footprint (~5 km) to obtain comprehensive information from observations. Based on the merged dataset, "warm rain" is generally identified as having averaging 10.8-μm brightness temperatures (TB10.8) exceeding 273 K and the existence of surface rainfall. However, this integration may lead to the misidentification of warm rain because the beam-filling problem (nonuniform TB10.8 in PR pixels) is not fully considered through the method using high-resolution TB10.8 to match low-resolution rainfall. To assess the bias that is associated with identifying warm rain, a new dataset that includes all VIRS signals within the PR resolution is established, and the characteristics of this warm rain in the summers of 1998-2012 are analyzed. The results show that clear-sky pixels and "cold" pixels probably exist in some apparent warm-rain cases (60.5% and 11.2% of the time, respectively). According to this finding, warm-rain pixels are divided into pixels with and without clear sky. Statistical analysis shows that the existence of clear-sky pixels has a huge influence on the characteristics of the warm-rain pixels. The implications of this study are that many of the warm-rain cases are in fact not warm rain. When studying warm rain, the situation whereby the edges of pixels are clear sky should be fully considered. Also, when computing the weighted average brightness temperature and other characteristics of warm-rain pixels, parts that are clear-sky or cold pixels should be expelled to mitigate beam-filling problems. © 2017 American Meteorological Society.

Hu W.,Hefei University of Technology | Hu W.,Lawrence Berkeley National Laboratory | Li Z.,Hefei University of Technology | Yang J.,Hefei University of Technology
Nano Research | Year: 2017

A single water molecule is nothing special. However, macroscopic water displays many anomalous properties at interfaces, such as hydrophobicity and hydrophilicity. Although the underlying mechanisms remain elusive, hydrogen bonds between water molecules are expected to play a major role in these interesting phenomena. An important question concerns whether water clusters containing few molecules are qualitatively different from a single molecule. Using the water adsorption behavior as an example and by carefully choosing two-dimensional silicene as the substrate material, we demonstrate that water monomers, dimers, and trimers show distinct adsorption properties at the substrate surface. On silicene, the additional water molecules in dimers and trimers induce a transition from physisorption to chemisorption and then to dissociation, arising from the enhancement of charge transfer and proton transfer processes induced by hydrogen bonding. Such a hydrogen bond autocatalytic effect is expected to have broad applications in metal-free catalysis for the oxygen reduction reaction and water dissociation.[Figure not available: see fulltext.] © 2017 Tsinghua University Press and Springer-Verlag Berlin Heidelberg

Meng J.,Hefei University of Technology | Li X.-H.,Hefei University of Technology | Han Z.-Y.,Hefei University of Technology
Organic Letters | Year: 2017

Herein, by employing a rhodium catalyst with a commercial ligand and a phosphoric acid catalyst, highly chemo-, regio-, and enantioselective hydroaminomethylation of olefins is realized through a relay catalytic hydroformylation/dynamic kinetic reductive amination process. The method features mild conditions (1 bar of syngas, room temperature in most cases), high yields (up to 99%), and high enantioselectivities (up to >99.5:0.5 er). Besides styrenes, acrylamides also provided the products with high yields and enantioselectivities. Aliphatic alkenes and vinyl esters are also applicable for the current method, albeit lower yields and enantioselectivities were obtained. © 2017 American Chemical Society.

Li W.-P.,Hefei University of Technology | Zheng Y.-F.,Hefei University of Technology | Zhao Y.-Y.,Hefei University of Technology
Precambrian Research | Year: 2017

High-resolution carbon and oxygen analyses, along with residue contents, major and trace element concentrations were carried out for marine dolostone from a profile through the Upper Ediacaran to the Lower Cambrian strata in South China. The results provide geochemical evidence for enhanced input of terrigenous material into seawater in this period. Four positive and four negative carbon isotope excursions are identified in this profile. The first remarkably negative δ13C excursion exhibits the lowest value down to −2‰ at the Ediacaran to Cambrian boundary (ECB), in agreement with the global δ13C and stratigraphy correlation. The second remarkably negative δ13Ccarb excursion is as low as −1.81‰ subsequent to a positive δ13Ccarb excursion as high as 1.74‰ in the Lower Cambrian. The ECB position in the stratigraphic profile is constrained by carbon isotope correlations. The decreases of dolostone δ18O and δ13C values are synchronous across the ECB, suggesting a change of the seawater composition at that time. The increase of residue contents is concordant with decreases of Y/Ho ratios and δ18O values for the dolostone across the ECB, suggesting the increase of terrigenous input in this period. The relatively smooth REE + Y patterns of dolostone suggest its deposition in the environment of continental platform. An integrated interpretation of these geochemical data, including the major and trace element concentrations, Mn/Sr and Mg/Ca ratios, and the well preserved dolostone δ13C and δ18O values, indicates that the terrigenous material from the continental weathering is rich in nutrients and 13C-depleted organic matter, which would have contributed to the negative δ13Ccarb excursion of dolostone at the stratigraphic boundaries. The strong positive δ13Ccarb excursion in the Lower Cambrian may be linked to the biological radiation with lots of organic matter buried from the seawater in this period. The fall and rise of sea level during different periods in the same region may result in differential input of terrigenous materials (including freshwater) into marine carbonates, recording the coupling between regional tectonism and paleoclimatic change on the continental platform. © 2017 Elsevier B.V.

Xia W.,Nanyang Technological University | Zhao P.,Nanyang Technological University | Zhao P.,Xi'an University of Science and Technology | Wen Y.,Nanyang Technological University | And 2 more authors.
IEEE Communications Surveys and Tutorials | Year: 2017

Data centers (DCs), owing to the exponential growth of Internet services, have emerged as an irreplaceable and crucial infrastructure to power this ever-growing trend. A DC typically houses a large number of computing and storage nodes, interconnected by a specially designed network, namely, DC network (DCN). The DCN serves as a communication backbone and plays a pivotal role in optimizing DC operations. However, compared to the traditional network, the unique requirements in the DCN, for example, large scale, vast application diversity, high power density, and high reliability, pose significant challenges to its infrastructure and operations. We have observed from the premium publication venues (e.g., journals and system conferences) that increasing research efforts are being devoted to optimize the design and operations of the DCN. In this paper, we aim to present a systematic taxonomy and survey of recent research efforts on the DCN. Specifically, we propose to classify these research efforts into two areas: 1) DCN infrastructure and 2) DCN operations. For the former aspect, we review and compare the list of transmission technologies and network topologies used or proposed in the DCN infrastructure. For the latter aspect, we summarize the existing traffic control techniques in the DCN operations, and survey optimization methods to achieve diverse operational objectives, including high network utilization, fair bandwidth sharing, low service latency, low energy consumption, high resiliency, and etc., for efficient DC operations. We finally conclude this survey by envisioning a few open research opportunities in DCN infrastructure and operations. © 2016 IEEE.

Yang X.,Hefei University of Technology | Chen H.,Hefei University of Technology
Zhendong yu Chongji/Journal of Vibration and Shock | Year: 2017

The transverse vibration characteristics of an axially moving beam immovably simply supported at both ends and subjected to a thermal shock were studied. Based on Timoshenko beam theory and Hamilton principle, the governing equations of its transverse vibration were established. The transverse vibration problem of the beam was solved by using the differential quadrature method. The effects of thermal shock and axially moving speed on its natural frequencies were analyzed. The results shwoed that among three factors including equivalent thermal axial force, equivalent thermal bending moment and changing of elastic modulus dut to thermal shock, equivalent thermal axial force plays a dominant role to affect natural frequencies of the beam, while changing of elastic modulus and equivalent thermal moment play a secondary role; when the thermal shock loads reach the critical load of the beam, the first order buckling mode is excited; thermal shock and axial moving speed can both reduce natural frequencies of the beam, and their joint action leads to the phenomenon of modal coupling to make the beam easily reach an unstable status. © 2017, Editorial Office of Journal of Vibration and Shock. All right reserved.

Deng Z.,Hefei University of Technology | Hu J.,Hefei University of Technology | Liu S.,Hefei University of Technology
Macromolecular Rapid Communications | Year: 2017

Reactive oxygen, nitrogen, and sulfur species (RONSS) are cross-reacting and involved in a myriad of physiological and pathological processes. Similar to acidic pH, overexpressed enzymes, and other specific stimuli found in pathological microenvironments, RONSS are recognized as a category of emerging triggering events and have been employed to design activatable theranostic nanomaterials. In this regard, a plethora of RONSS-responsive nanovectors including polymeric micelles and vesicles (also referred to as polymersomes) are constructed. In comparison with micelles, polymersomes comprising aqueous interiors enclosed by hydrophobic membranes show intriguing applications in synergistic delivery of both hydrophobic and hydrophilic drugs, nanoreactors, and artificial organelles. This feature article focuses on the recent developments in the fabrication of RONSS-responsive polymersomes and their potential biomedical applications in terms of triggered drug delivery. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Yu Z.,Hefei University of Technology | Li A.,Hefei University of Technology | Wang M.,Hefei University of Technology
BMC Medical Genomics | Year: 2017

Background: Copy number alterations (CNA) and loss of heterozygosity (LOH) represent a large proportion of genetic structural variations of cancer genomes. These aberrations are continuously accumulated during the procedure of clonal evolution and patterned by phylogenetic branching. This invariably results in the emergence of multiple cell populations with distinct complement of mutational landscapes in tumor sample. With the advent of next-generation sequencing technology, inference of subclonal populations has become one of the focused interests in cancer-associated studies, and is usually based on the assessment of combinations of somatic single-nucleotide variations (SNV), CNA and LOH. However, cancer samples often have several inherent issues, such as contamination of normal stroma, tumor aneuploidy and intra-tumor heterogeneity. Addressing these critical issues is imperative for accurate profiling of clonal architecture. Methods: We present CLImAT-HET, a computational method designed for capturing clonal diversity in the CNA/LOH dimensions by taking into account the intra-tumor heterogeneity issue, in the case where a reference or matched normal sample is absent. The algorithm quantitatively represents the clonal identification problem using a factorial hidden Markov model, and takes an integrated analysis of read counts and allele frequency data. It is able to infer subclonal CNA and LOH events as well as the fraction of cells harboring each event. Results: The results on simulated datasets indicate that CLImAT-HET has high power to identify CNA/LOH segments, it achieves an average accuracy of 0.87. It can also accurately infer proportion of each clonal population with an overall Pearson correlation coefficient of 0.99 and a mean absolute error of 0.02. CLImAT-HET shows significant advantages when compared with other existing methods. Application of CLImAT-HET to 5 primary triple negative breast cancer samples demonstrates its ability to capture clonal diversity in the CAN/LOH dimensions. It detects two clonal populations in one sample, and three clonal populations in one other sample. Conclusions: CLImAT-HET, a novel algorithm is introduced to infer CNA/LOH segments from heterogeneous tumor samples. We demonstrate CLImAT-HET’s ability to accurately recover clonal compositions using tumor WGS data without a match normal sample. © 2017 The Author(s).

Zhang G.,Hefei University of Technology | Chen X.,Hefei University of Technology
Dianli Zidonghua Shebei/Electric Power Automation Equipment | Year: 2017

The energy internet, which integrates different technologies, such as electric power, internet, information, and so on, can be constructed based on the concept of internet. The concept, characteristics and frameworks of energy internet are elaborated, its key components, including distributed renewable energy, energy storage devices and energy routers, are briefly introduced, and its domestic and foreign developments are summarized, based on which, a number of issues possibly encountered in its future development are illustrated and analyzed, such as grid-connected distributed energy, large-scale energy storage technology, interface standards, information interconnection system construction, power market & service improvement, etc. © 2017, Electric Power Automation Equipment Press. All right reserved.

Aeschynite-type La1−xLnxTiNbO6 (Ln=Ce, Sm, x=0–1) ceramics were prepared via a conventional solid state method. Analysis of X-ray diffraction, Raman, infrared reflectivity spectra and the microstructures revealed a series of composition-induced phase evolution in sequence: monoclinic→coexistence of monoclinic and orthorhombic→orthorhombic structure, i.e. M→M+O→O. The critical compositions of distinguishing the dominant M or O phase were x=0.15 in La1−xCexTiNbO6 and x=0.10 in La1−xSmxTiNbO6 ceramics, exactly corresponding to the average ionic radius of rare earth ions (IR) ~1.027 Å. The crystal structure and microwave dielectric properties of RETiNbO6 (RE=rare earth) ceramics strongly depended on IR. Near-zero τf was achieved in the Ce-sample with x=0.153 (εr=28.9, Q×f=17,275 GHz@6.54 GHz) as well as in the Sm-sample with x=0.098 (εr=28.2, Q×f=19,186 GHz@6.78 GHz). Eventually, RETiNbO6 would form O euxenite (-τf), O aeschynite (+τf), and M aeschynite (-τf), as IR<0.945 Å, 0.945 Å

Huang Q.,Hefei University of Technology | Huang Q.,Suncore Photovoltaic Technology | Xu L.,Hefei University of Technology
Solar Energy | Year: 2017

Various measures should be taken to optimize the performance, minimize the cost and improve the reliability of CPV concentrator. This paper presents theoretical analysis and experimental verification on a concentrator optical system with geometrical concentration ratio of 625× consisting of a Fresnel lens as primary optical element, a ball lens as secondary optical element and a solar receiver. The solar cell and the ball lens are separated by a small air gap in this proposed CPV system and the ball lens is mounted mechanically on the receiver to enhance the reliability of the CPV system. Test results show that a power generation efficiency of 30.3% and acceptance angle of 0.72° can be obtained for a CPV device with Fresnel lens, ball lens with AR coatings and solar cell with efficiency of 40%. © 2017

Zhang Y.,University of Science and Technology of China | Hu W.,Hefei University of Technology
Materials | Year: 2017

Nonlinear optical properties of a series of newly-synthesized molecular fluorescent probes for Hg2+ containing the same acceptor (rhodamine group) are analyzed by using time-dependent density functional theory in combination with analytical response theory. Special emphasis is placed on evolution of the probes' optical properties in the absence and presence of Hg2+. These compounds show drastic changes in their photoabsorption and photoemission properties when they react with Hg2+, indicating that they are excellent candidates for ratiometric and colorimetric fluorescent chemosensors. Most importantly, the energy donor moiety is found to play a dominant role in sensing performance of these probes. Two-photon absorption cross sections of the compounds are increased with the presence of Hg2+, which theoretically suggests the possibility of the probes to be two-photon fluorescent Hg2+ sensors. Moreover, analysis of molecular orbitals is presented to explore responsive mechanism of the probes, where the fluorescence resonant energy transfer process is theoretically demonstrated. Our results elucidate the available experimental measurements. This work provides guidance for designing efficient two-photon fluorescent probes that are geared towards biological and chemical applications. © 2017 by the authors.

Zheng D.,Hefei University of Technology | Zuo R.,Hefei University of Technology
Journal of the European Ceramic Society | Year: 2017

A new ternary lead-free (0.67-x)BiFeO3-0.33BaTiO3-xLa(Mg1/2Ti1/2)O3 ferroelectric ceramic exhibited an obvious evolution of dielectric relaxation behavior. A significantly enhanced energy-storage property was observed at room temperature, showing a good energy-storage density of 1.66 J/cm3 at 13 kV/mm and a relatively high energy-storage efficiency of 82% at x = 0.06. This was basically ascribed to the formation of a slim polarization-electric field hysteresis loop, in which a high saturated polarization Pmax and a rather small remnant polarization Pr were simultaneously obtained. Particularly, its energy storage properties were found to depend weakly on frequency (0.2 Hz–100 Hz), and also to exhibit a good stability against temperature (25 °C–180 °C). The achievement of these characteristics was attributed to both a rapid response of the electric field induced reversible ergodic relaxor to long-range ferroelectric phase transition and a typical diffuse phase transformation process in the dielectric maxima. © 2016 Elsevier Ltd

Arroyo J.E.C.,Federal University of Viçosa | Leung J.Y.-T.,Hefei University of Technology | Leung J.Y.-T.,New Jersey Institute of Technology
Computers and Operations Research | Year: 2017

This research analyzes the problem of scheduling a set of n jobs with arbitrary job sizes and non-zero ready times on a set of m unrelated parallel batch processing machines so as to minimize the makespan. Unrelated parallel machine is a generalization of the identical parallel processing machines and is closer to real-world production systems. Each machine can accommodate and process several jobs simultaneously as a batch as long as the machine capacity is not exceeded. The batch processing time and the batch ready time are respectively equal to the largest processing time and the largest ready time among all the jobs in the batch. Motivated by the computational complexity and the practical relevance of the problem, we present several heuristics based on first-fit and best-fit earliest job ready time rules. We also present a mixed integer programming model for the problem and a lower bound to evaluate the quality of the heuristics. The small computational effort of deterministic heuristics, which is valuable in some practical applications, is also one of the reasons that motivates this study. The results show that the heuristic proposed in this paper has a superior performance compared to the heuristics based on ideas proposed in the literature. © 2016 Elsevier Ltd

Dong G.,Hefei University of Technology | Chen Z.,Hefei University of Technology | Wei J.,Hefei University of Technology
International Journal of Mechanical Engineering and Robotics Research | Year: 2017

Rechargeable battery systems are key components of applications in on-board storage for Micro-grids and electric vehicles. One of the most important evaluation indexes for energy storage system is the peak power capability information, which is used to evaluate the instantaneous power capability of battery systems to release or absorb electrical energy. To give out an accurate peak power capability estimation method for series-connected lithium-ion battery pack, this paper first proposed an extended Kalman filter based state-of-charge estimation method. Then the estimated state-of-charges and predicted terminal voltages of the cells in a series-connected lithium-ion battery pack are regarded as the constraints of peak power capability. Finally, the proposed method is verified by experiments conducted on a 6-series LiFePO4 battery pack. © 2017 Int. J. Mech. Eng. Rob. Res.

Zhang J.,Ohio State University | Yao H.,Ohio State University | Rizzoni G.,Hefei University of Technology
IEEE Transactions on Vehicular Technology | Year: 2017

Functional safety is of great importance for electric and hybrid electric vehicles (EV/HEVs). One way to improve functional safety of EV/HEVs is to develop reliable and robust onboard diagnostics (OBD) so that, once a component fault is detected, effective remedial actions are taken to avoid system failures. In this paper, we develop a systematic model-based diagnostic approach based on structural analysis for electric drive systems that can form the basis of OBD design for EVs. The structural analysis approach for fault detection and isolation (FDI) evaluates a system's structural model, using the mathematical model of the system in matrix form, from which it is possible to determine the analytic redundancy and to design the structured residuals. In this paper, we demonstrate the application of this methodology by carrying out the design of a diagnostic approach for permanent-magnet synchronous machine (PMSM) drive systems of EVs, with specific focus on sensor fault diagnosis. The diagnostic approach is first verified through a simulation study on the EcoCAR2 vehicle, which is a plug-in HEV developed by the Center for Automotive Research at The Ohio State University, and is then further validated through an experimental study on a test bench consisting of a three-phase inverter enabled by the TMS320F28035 digital signal processor and a PMSM. © 1967-2012 IEEE.

Yang S.,Hefei University of Technology
Renewable and Sustainable Energy Reviews | Year: 2017

The invention and application of the electric power technology triggered the second industrial revolution in human history, which marked the human society entered the age of electricity. Electricity provides the sustainable power for economic and social development. With the rapid development of economy, the electricity consumption is also increasing. The increase of electricity consumption has further promoted the progress of the industrial economy. In order to achieve the goal of improving the level of economic development while reducing energy consumption, it is necessary to reveal the relationship between electricity consumption and economic growth. This study is an extensive overview of the literature surrounding this topic. In this paper, we focus on the relationship between electricity consumption and economic growth in China. We first analyze the general situation of China's electricity consumption and economic development. Then we explore the relationship between China's electricity consumption and economic growth from three dimensions, i.e., the time dimension, the regional dimension and the industrial dimension. Finally, we study the key issues in the research of the relationship between electricity consumption and economic growth, including variable selection, model construction and results discussion. This work suggests that the nature of the nexus in China should and can be explored from a wider perspective, by developing a suitable integrated methodological framework. © 2017 Elsevier Ltd

Wang S.-L.,Hefei University of Technology | Zhong L.,Hefei University of Technology | Song Q.-H.,Hefei University of Technology
Chemical Communications | Year: 2017

A ratiometric fluorescent chemosensor, Phos-1, was constructed with 4,5-diaminonaphthalimide as a fluorophore for selective and visual detection of phosgene. The sensing mechanism was demonstrated to be the phosgene molecule acylating both amine groups of Phos-1. A test paper with Phos-1 was fabricated for facile, selective and visual detection of phosgene gas. © The Royal Society of Chemistry.

Xiang D.,Hefei University of Technology | Wang Z.,Hefei University of Technology
Multimedia Tools and Applications | Year: 2017

Salient object detection aims to identify both spatial locations and scales of the salient object in an image. However, previous saliency detection methods generally fail in detecting the whole objects, especially when the salient objects are actually composed of heterogeneous parts. In this work, we propose a saliency bias and diffusion method to effectively detect the complete spatial support of salient objects. We first introduce a novel saliency-aware feature to bias the objectness detection for saliency detection on a given image and incorporate the saliency clues explicitly in refining the saliency map. Then, we propose a saliency diffusion method to fuse the saliency confidences of different parts from the same object for discovering the whole salient object, which uses the learned visual similarities among object regions to propagate the saliency values across them. Benefiting from such bias and diffusion strategy, the performance of salient object detection is significantly improved, as shown in the comprehensive experimental evaluations on four benchmark data sets, including MSRA-1000, SOD, SED, and THUS-10000. © 2016, Springer Science+Business Media New York.

Zhu K.,CAS Hefei Institutes of Physical Science | Yu X.,CAS Hefei Institutes of Physical Science | Yu X.,Hefei University of Technology
Mechanical Systems and Signal Processing | Year: 2017

In micro milling, the tool wear condition is key to the geometrical and surface integrity of the product. This study proposes a novel tool wear surface area monitoring approach based on the full tool wear image, which can reflect the tool conditions better than the traditional tool wear width criteria. To meet the challenges of heavy noise, blur boundary, and mis-alignment of the captured tool wear images, this paper develops a region growing algorithm based on morphological component analysis (MCA) to solve the problems. It decomposes the original micro milling tool image into target tool images, background image and noise image. Then, the region growing algorithm is used to detect the defect and extract the wear region of the target tool image. In addition, rotation invariant features are extracted from wear region to overcome the inconsistency of wear image orientation. The experiment results show that region growing based on MCA algorithm can extract the wear region of the target tool image effectively and the extracted wear region also has good indication of tool wear conditions. It also demonstrates that the estimation of wear area can generalize the tool wear width estimation approach, and yield more accurate results than the traditional approaches. © 2017 Elsevier Ltd

Ma D.,Hefei University of Technology
Journal of Geophysical Research: Atmospheres | Year: 2017

Using a low-frequency six-station local network, preliminary breakdown (PB) pulses not followed or followed by negative return stroke (RS), which are defined as PB-type and PB cloud-to-ground (PBCG)-type flashes, are analyzed based on four isolated small thunderstorms for the first time. On the basis of 22 PB-type flashes out of totally 2155 flashes, it indicates that the number of PB-type flashes is very small. At the early stage, PB-type flashes are observed in all four thunderstorms. At the active stage, PB-type flashes still can occur; meanwhile, there are few or no negative cloud-to-ground (CG) flashes. However, at the final stage no PB-type flashes occur. At the stage of distinct cell merging or splitting, PB-type flashes are also observed. Based on the 123 PBCG-type flashes, we discuss the percentage of PBCG-type flashes and also analyze the relationship between the electric field (E-field) amplitude of the largest pulse in the PB pulse train normalized to 100km (PBA), the E-field amplitude of the first return stroke normalized to 100km (RSA), the time interval between PBA and RSA (PB-RS interval), and the ratio between PBA and RSA (PB-RS ratio). We find that the percentage of PBCG-type flashes is not always dependent on PBA or PB-RS ratio; the type of thunderstorms may also have an impact on this percentage. None of the PB-RS intervals is less than 20ms; we speculate that such long PB-RS interval is the feature of isolated small thunderstorms, but more observations are needed to further investigate this question. © 2017. American Geophysical Union. All Rights Reserved.

Zhang G.,Hefei University of Technology | Zhang G.,Academia Sinica, Taiwan
EPJ Web of Conferences | Year: 2017

If the Higgs boson discovered at the Large Hadron Collider (LHC) is not exactly the one in the Standard Model, an alternative mechanism is needed to restore unitarity in the scattering amplitude of longitudinal gauge bosons, and new resonances may appear. This paper presents a search for new heavy neutral resonances (R) produced through vector boson fusion process qq → Rqq → ℓ+νℓ qq (ℓ = e; μ) using 3.2 fb-1 of data at p s = 13 TeV recorded by the ATLAS detector at the LHC. No excess above the Standard Model background expectation is observed. Limits are set on the production of five types of neutral resonances with different spin and isospin quantum numbers using a K-matrix unitarization of the vector boson scattering process. © The Authors, published by EDP Sciences, 2017.

Sun L.,Hefei University of Technology | Gao P.,Hefei University of Technology
eLife | Year: 2017

Targeting the transcription factor c-Myc via one of its coactivator proteins is a promising strategy for cancer therapy. © 2017, eLife Sciences Publications Ltd. All rights reserved.

Hou J.,Hefei University of Technology | Chan E.H.,Hong Kong Polytechnic University
Sustainable Development | Year: 2017

The important factors for successfully implementing transfer of development rights (TDR) programs have been explored. However, these factors are not yet adequate to guide the practice directly, especially for those cities at the early stage of exploring TDR. This research aims to find out how different cities/counties put these successful factors into practice to achieve sustainable conservation of built heritage by adopting a successful TDR framework to conduct a systematic comparison of 15 cities/counties internationally. The research identifies six key factors included in most policy approaches in practice. Interviews are carried out with local experts in Hong Kong as a case study to understand how these factors can be implemented in the local context. Through coding of the interview data using NVivo, the analyses also show how these factors are interrelated to each other. The results have not only contributed to better understanding of the theory of implementing TDR in general, but also provided useful guidance for sustainable TDR practice. © 2017 John Wiley & Sons, Ltd and ERP Environment.

Ren G.,Hefei University of Technology | Zhu Z.,Hefei University of Technology
Complex Analysis and Operator Theory | Year: 2017

A natural question in discrete complex analysis is whether the Taylor series of a discrete holomorphic function is convergent to itself in the whole grid (Formula presented.). In this paper we answer this question in the affirmative in the setting of a new kind of discrete holomorphic function on the square grid (Formula presented.) with values in split quaternions based on the methods of Sheffer sequences. On the other hand, we also establish the integral theory for this new kind of discrete holomorphic functions, including the discrete Green theorem and the Cauchy integral formula. In contrast to the discrete Clifford analysis, we obtain a new version of the discrete Cauchy integral formula without the extra error term. © 2017 Springer International Publishing

Mokhtari A.,University of Pennsylvania | Ling Q.,Hefei University of Technology | Ribeiro A.,University of Pennsylvania
IEEE Transactions on Signal Processing | Year: 2017

We study the problem of minimizing a sum of convex objective functions, where the components of the objective are available at different nodes of a network and nodes are allowed to only communicate with their neighbors. The use of distributed gradient methods is a common approach to solve this problem. Their popularity notwithstanding, these methods exhibit slow convergence and a consequent large number of communications between nodes to approach the optimal argument because they rely on first-order information only. This paper proposes the network Newton (NN) method as a distributed algorithm that incorporates second-order information. This is done via distributed implementation of approximations of a suitably chosen Newton step. The approximations are obtained by truncation of the Newton step's Taylor expansion. This leads to a family of methods defined by the number K of Taylor series terms kept in the approximation. When keeping K terms of the Taylor series, the method is called NN-K and can be implemented through the aggregation of information in K-hop neighborhoods. Convergence to a point close to the optimal argument at a rate that is at least linear is proven and the existence of a tradeoff between convergence time and the distance to the optimal argument is shown. The numerical experiments corroborate reductions in the number of iterations and the communication cost that are necessary to achieve convergence relative to first-order alternatives. © 2016 IEEE.

Zhou Z.,Hefei University of Technology | Hao S.,Hefei University of Technology
Neurocomputing | Year: 2017

The availability of 3D human body shapes enables applications such as digital anthropometry by exploiting the geometric information of 3D shapes. In this paper, we propose a method for detecting anatomical landmarks on 3D human shapes by hierarchically utilizing multiple shape features. The backbone of our method is to compute dense correspondences between a pair of template and target shape, and the detection is achieved by transferring the annotated landmarks of the template shape to the target shape. We also investigate several techniques to further enhance the detecting accuracy, such as template selection, fine search and late fusion. Multiple kinds of shape features are used in different parts of our method, and each of them contributes to the improvement of detection accuracy. In experiments, we validate the effectiveness of each part in the proposed method. And our method also demonstrates the state-of-the-art performance in terms of the average detection accuracy. © 2017.

Zhou X.,Hefei University of Technology
Nuclear and Particle Physics Proceedings | Year: 2017

The BESIII Experiment at the Beijing Electron Positron Collider (BEPCII) has accumulated the world's largest e+e− collision samples at ψ(3770) peak, around the ψ(4040) nominal mass, at DS +DS − mass threshold and at the Λc +Λ‾c − pair mass threshold, which allow us to study decays of charmed mesons and baryons in a uniquely clean background. We report the measurements of the D(s) + decay constants, the form factors of D semi-leptonic decays, the CKM matrix elements |Vcs(d)|, the D(s) + hadronic decays, and the search for charm rare decays. © 2016 Elsevier B.V.

Yang J.,Hefei University of Technology | Zhu Y.,Hefei University of Technology
Physics of Fluids | Year: 2017

A convergent channel method is applied to create an imploding arc shock as a partial representative of an overall cylindrical shock. The self-ignition phenomenon induced by such an imploding shock is investigated experimentally and numerically. Agreements between experimental and numerical results are widely reached not only for the shock imploding process but also for shock reflection and features of self-ignition, which approves the validity of the method. The induced self-ignition is found to lag behind the incident shock front and experience a shockless spontaneous process before the onset of detonation. The mechanisms are briefly addressed. © 2017 Author(s).

Jayakumar M.K.G.,National University of Singapore | Bansal A.,National University of Singapore | Huang K.,National University of Singapore | Yao R.,Hefei University of Technology | And 3 more authors.
ACS Nano | Year: 2014

Current nanoparticle-based gene delivery techniques face two major limitations, namely, endosomal degradation and poor cytosolic release of the nanoparticles and nonspecificity of treatment. These limitations can be overcome with certain light-based techniques, such as photochemical internalization to enable endosomal escape of the delivered nanoparticles and light-controlled gene expression to overcome the nonspecific effects. However, these techniques require UV/visible light, which is either phototoxic and/or has low tissue penetration capabilities, thus preventing their use in deep tissues in a clinical setting. In an effort to overcome these barriers, we have successfully demonstrated a light-based gene delivery system that significantly boosts cytosolic gene delivery, with precise control over gene expression and the potential for use in nonsuperficial tissues. Core-shell fluorescent upconversion nanoparticles excited by highly penetrating near-infrared radiation and emitting simultaneously in the ultraviolet and visible ranges were synthesized and used as remote nanotransducers to simultaneously activate endosomal escape and gene knockdown. Gene knockdown using photomorpholinos was enhanced as much as 30% in vitro compared to the control without endosomal escape facilitation. A similar trend was seen in vivo in a murine melanoma model, demonstrating the enormous clinical potential of this system. © 2014 American Chemical Society.

Bian Y.,Shanghai University | He P.,Hefei University of Technology | Xu H.,Anhui University
Energy Policy | Year: 2013

In the process of setting operational targets to achieve sustainable development of economy, environment and natural resources, estimation of potential energy saving and potential CO2 emission reduction becomes extremely important. This estimation can be conducted based on the energy efficiency evaluation for different decision-making units (DMUs) by data envelopment analysis (DEA). Non-fossil energy is an important component of energy consumption in China, and it has great impacts on energy efficiency and energy-related carbon dioxide (CO2) emissions. This paper proposes a non-radial DEA model to evaluate regional energy efficiencies in China. In the proposed model, non-fossil energy is treated as a fixed input. Based on the model, a method of measuring potential energy saving and CO2 emission reduction for efficiency improvement is also presented. The proposed approaches are illustrated by using a regional dataset in China. Based on the application results, some implications for improving energy efficiency and reducing CO2 emissions in China are provided. © 2013 Elsevier Ltd.

Tang W.,Hefei University of Technology | Tang W.,National University of Singapore | Yu S.,Hefei University of Technology | Yu S.,National University of Singapore | Oh C.H.,National University of Singapore
Physical Review Letters | Year: 2013

One fascinating way of revealing quantum nonlocality is the all-versus-nothing test due to Greenberger, Horne, and Zeilinger (GHZ) known as the GHZ paradox. So far genuine multipartite and multilevel GHZ paradoxes are known to exist only in systems containing an odd number of particles. Here we shall construct GHZ paradoxes for an arbitrary number (greater than 3) of particles with the help of qudit graph states on a special kind of graphs, called GHZ graphs. Furthermore, based on the GHZ paradox arising from a GHZ graph, we derive a Bell inequality with two d-outcome observables for each observer, whose maximal violation attained by the corresponding graph state, and a Kochen-Specker inequality testing the quantum contextuality in a state-independent fashion. © 2013 American Physical Society.

Idris N.M.,National University of Singapore | Jayakumar M.K.G.,National University of Singapore | Bansal A.,National University of Singapore | Zhang Y.,National University of Singapore | Zhang Y.,Hefei University of Technology
Chemical Society Reviews | Year: 2015

Remote activation of photoactivable therapeutic compounds by light provides a high spatial and temporal control for activating the therapeutic agent. However, photoactivable compounds are mostly responsive towards ultraviolet (UV) or visible light radiation that has poor tissue penetration depth besides being unsafe to the body in the case of UV light. Nanoparticles with energy upconversion hold potential in overcoming this limit by using safe and deeply penetrating near-infrared (NIR) light. These upconversion nanoparticles (UCNs) act as versatile nanotransducers as they convert NIR light to light of shorter wavelengths that can be tuned to the NIR, visible or UV colors to suit different activation wavelengths. Their highly unusual optical properties to fluoresce with near-zero photobleaching, photoblinking and background autofluorescence are unique and an added benefit when used simultaneously as optional imaging agents. This article reviews recent advancements in the use of UCNs for photoactivation of therapeutic agents. Specifically, we discuss the use of these UCNs for activation of light-sensitive/photocaged molecules or photosensitizers for photocontrolled-delivery and photodynamic therapy. This journal is © The Royal Society of Chemistry.

Chen Y.-L.,Peking University | Zou C.-L.,Hefei University of Technology | Hu Y.-W.,Peking University | Gong Q.,Peking University
Physical Review A - Atomic, Molecular, and Optical Physics | Year: 2013

This paper investigates the confinement and quality (Q) factors of the dielectric mode, exterior surface plasmonic mode, and interior surface plasmonic mode in a metal-nanolayer-coated silica microtoroid. It is found that the confinement of these modes relies mainly on the real part of the coating-metal permittivity, and a smaller negative real part produces a lower effective potential barrier which plays distinct roles in these three types of modes. For the exterior plasmonic mode, a lower potential leads to a better confinement and thus lower radiation losses, while for the interior plasmonic mode and the dielectric mode, a higher potential can play a very positive role in suppressing the radiation losses. The metal absorption loss, as expected, is directly related to the imaginary part of the metal permittivity and the energy fraction of the mode in the metal layer, and the latter depends on the confinement or, namely, the effective potential barrier induced by the metal nanolayer. We also compare the plasmonic modes in the coated microcavity and the dielectric modes in the uncoated microcavity at different cavity sizes. An interesting finding is that when the cavity is small enough, which is highly desirable for compact photonic devices, the Q factors of the plasmonic modes even exceed significantly that of the uncoated dielectric modes. © 2013 American Physical Society.

Gao Y.,Tsinghua National Laboratory for Information Sciences and Technology | Gao Y.,National University of Singapore | Wang M.,Hefei University of Technology | Ji R.,Xiamen University | And 3 more authors.
IEEE Transactions on Industrial Electronics | Year: 2014

In view-based 3-D object retrieval, each object is described by a set of views. Group matching thus plays an important role. Previous research efforts have shown the effectiveness of Hausdorff distance in group matching. In this paper, we propose a 3-D object retrieval scheme with Hausdorff distance learning. In our approach, relevance feedback information is employed to select positive and negative view pairs with a probabilistic strategy, and a view-level Mahalanobis distance metric is learned. This Mahalanobis distance metric is adopted in estimating the Hausdorff distances between objects, based on which the objects in the 3-D database are ranked. We conduct experiments on three testing data sets, and the results demonstrate that the proposed Hausdorff learning approach can improve 3-D object retrieval performance. © 2013 IEEE.

Leng C.,National University of Singapore | Zhang W.,Hefei University of Technology
Statistics and Computing | Year: 2014

Quantile regression has become a powerful complement to the usual mean regression. A simple approach to use quantile regression in marginal analysis of longitudinal data is to assume working independence. However, this may incur potential efficiency loss. On the other hand, correctly specifying a working correlation in quantile regression can be difficult. We propose a new quantile regression model by combining multiple sets of unbiased estimating equations. This approach can account for correlations between the repeated measurements and produce more efficient estimates. Because the objective function is discrete and non-convex, we propose induced smoothing for fast and accurate computation of the parameter estimates, as well as their asymptotic covariance, using Newton-Raphson iteration. We further develop a robust quantile rank score test for hypothesis testing. We show that the resulting estimate is asymptotically normal and more efficient than the simple estimate using working independence. Extensive simulations and a real data analysis show the usefulness of the method. © 2012 Springer Science+Business Media New York.

Kong X.-K.,Hefei University of Technology | Chen C.-L.,Hefei University of Technology | Chen Q.-W.,Hefei University of Technology | Chen Q.-W.,University of Science and Technology of China
Chemical Society Reviews | Year: 2014

Graphene has attracted increasing attention in different scientific fields including catalysis. Via modification with foreign metal-free elements such as nitrogen, its unique electronic and spin structure can be changed and these doped graphene sheets have been successfully employed in some catalytic reactions recently, showing them to be promising catalysts for a wide range of reactions. In this review, we summarize the recent advancements of these new and interesting catalysts, with an emphasis on the universal origin of their catalytic mechanisms. We are full of hope for future developments, such as more precisely controlled doping methods, atom-scale surface characterization technology, generating more active catalysts via doping, and finding wide applications in many different fields. This journal is © the Partner Organisations 2014.

Jiang G.,Hefei University of Technology | Jiang G.,University of Victoria | Pichaandi J.,University of Victoria | Johnson N.J.J.,University of Victoria | And 2 more authors.
Langmuir | Year: 2012

Ligands on the nanoparticle surface provide steric stabilization, resulting in good dispersion stability. However, because of their highly dynamic nature, they can be replaced irreversibly in buffers and biological medium, leading to poor colloidal stability. To overcome this, we report a simple and effective cross-linking methodology to transfer oleate-stabilized upconverting NaYF 4 core/shell nanoparticles (UCNPs) from hydrophobic to aqueous phase, with long-term dispersion stability in buffers and biological medium. Amphiphilic poly(maleic anhydride-alt-1-octadecene) (PMAO) modified with and without poly(ethylene glycol) (PEG) was used to intercalate with the surface oleates, enabling the transfer of the UCNPs to water. The PMAO units on the phase transferred UCNPs were then successfully cross-linked using bis(hexamethylene)triamine (BHMT). The primary advantage of cross-linking of PMAO by BHMT is that it improves the stability of the UCNPs in water, physiological saline buffers, and biological growth media and in a wide range of pH values when compared to un-cross-linked PMAO. The cross-linked PMAO-BHMT coated UCNPs were found to be stable in water for more than 2 months and in physiological saline buffers for weeks, substantiating the effectiveness of cross-linking in providing high dispersion stability. The PMAO-BHMT cross-linked UCNPs were extensively characterized using various techniques providing supporting evidence for the cross-linking process. These UCNPs were found to be stable in serum supplemented growth medium (37 °C) for more than 2 days. Utilizing this, we demonstrate the uptake of cross-linked UCNPs by LNCaP cells (human prostate cancer cell line), showing their utility as biolabels. © 2012 American Chemical Society.

Zhou M.,Zhejiang Normal University | Gao X.,Zhejiang Normal University | Hu Y.,Zhejiang Normal University | Chen J.,Hefei University of Technology | Hu X.,Nanyang Technological University
Applied Catalysis B: Environmental | Year: 2013

Uniform hamburger-like mesoporous carbon-incorporated ZnO (MC-ZnO) nanoarchitectures were facilely prepared by a simple, economical and environmentally benign solvothermal method using ethylene glycol (EG) as solvent in the presence of glucose. The as-obtained samples possessed a high surface area of 104m2g-1 and narrow pore size distribution around 7.2nm. The adsorption behavior of Congo red (CR) onto the products fitted well the Langmuir isotherm and the adsorption process followed the pseudo-second-order kinetic model. The maximum adsorption capacity of CR as 162mgg-1 was achieved by Langmuir equation, while only 18.8mgg-1 was found for by commercial ZnO nanoparticles. Furthermore, the as-prepared nanoarchitectures exhibited enhanced photocatalytic activity for the decolorization of photosensitized dyes (CR and rhodamine-B) under visible-light illumination. Therefore, the MC-ZnO nanoarchitectures developed in this work may be a promising potential material for wastewater treatment. © 2013 Elsevier B.V..

Zhang Y.,Hefei University of Technology | Deng B.,Hefei University of Technology | Zhang T.,CAS Technical Institute of Physics and Chemistry | Gao D.,Hefei University | Xu A.-W.,Hefei University of Technology
Journal of Physical Chemistry C | Year: 2010

Perfect mixed 26-facet and 18-facet polyhedra of Cu2O microcrystals were successfully synthesized by a hydrothermal process with use of stearic acid as a structure-directing agent. Cu2O octahedra and cubes were also prepared under hydrothermal conditions. The obtained microstructures were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), high-resolution TEM (HRTEM), and UV-vis spectrum. The adsorption and photocatalytic activity of as-prepared 26-facet and 18-facet Cu2O polyhedra for decomposition of methyl orange were investigated and compared to that of octahedra and cubes. The results show that mixed 26-facet and 18-facet polyhedra with dominant {110} facets have a higher adsorption and photocatalytic activity than Cu2O octahedra with dominant {111} surfaces and cubes with {100} surfaces. A higher surface energy and a greater density of the Cu dangling bonds on {110} facets of 26-facet and 18-facet polyhedra may be ascribed to its higher catalytic activity. Moreover, as compared with octahedra and cubes, mixed 26-facet and 18-facet polyhedra have more edges and corners, which could improve photocatalytic activity. This simple one-pot synthetic route could provide a good starting point for the research of morphology construction and shape-dependent catalytic properties of other materials. © 2010 American Chemical Society.

Zhao W.,Hefei University of Technology | Zhang Y.,Hefei University of Technology | You X.-P.,Southwest University | Zhu Z.-H.,Beijing Normal University
Physical Review D - Particles, Fields, Gravitation and Cosmology | Year: 2013

Measurement of pulsar timing residuals provides a direct way to detect relic gravitational waves at the frequency f∼1/yr. In this paper, we investigate the constraints on the inflationary parameters, the tensor-to-scalar ratio r, and the tensor spectral index nt, by the current and future pulsar timing arrays. We find that the Five-hundred-meter Aperture Spherical Radio Telescope in China and the planned Square Kilometre Array projects have fairly strong abilities to test the phantomlike inflationary models. If r=0.1, then Five-hundred-meter Aperture Spherical Radio Telescope could give the constraint on the spectral index nt<0.56 and Square Kilometre Array could give nt<0.32, while an observation with total time T=20 yr, pulsar noise level σw=30 ns, and monitored pulsar number n=200 could even constrain nt<0.07. These are much tighter than those inferred from the current results of the Parkes Pulsar Timing Array, European Pulsar Timing Array, and North American Nanohertz Observatory for Gravitational Waves. By studying the effects of various observational factors on the sensitivities of pulsar timing arrays, we find that compared with σw and n, the total observation time T has the most significant effect. © 2013 American Physical Society.

Xu L.D.,CAS Institute of Computing Technology | Xu L.D.,Shanghai JiaoTong University | Xu L.D.,Hefei University of Technology | Xu L.D.,Old Dominion University | And 2 more authors.
IEEE Transactions on Industrial Informatics | Year: 2014

Internet of Things (IoT) has provided a promising opportunity to build powerful industrial systems and applications by leveraging the growing ubiquity of radio-frequency identification (RFID), and wireless, mobile, and sensor devices. A wide range of industrial IoT applications have been developed and deployed in recent years. In an effort to understand the development of IoT in industries, this paper reviews the current research of IoT, key enabling technologies, major IoT applications in industries, and identifies research trends and challenges. A main contribution of this review paper is that it summarizes the current state-of-the-art IoT in industries systematically. © 2005-2012 IEEE.

Zhang W.,Hefei University of Technology | Leng C.,National University of Singapore
Biometrika | Year: 2012

We propose new regression models for parameterizing covariance structures in longitudinal data analysis. Using a novel Cholesky factor, the entries in this decomposition have a moving average and log-innovation interpretation and are modelled as linear functions of covariates. We propose efficient maximum likelihood estimates for joint mean-covariance analysis based on this decomposition and derive the asymptotic distributions of the coefficient estimates. Furthermore, we study a local search algorithm, computationally more efficient than traditional all subset selection, based on bic for model selection, and show its model selection consistency. Thus, a conjecture of Pan & MacKenzie (2003) is verified. We demonstrate the finite-sample performance of the method via analysis of data on CD4 trajectories and through simulations. © 2011 Biometrika Trust.

Varcoe J.R.,University of Surrey | Atanassov P.,University of New Mexico | Dekel D.R.,Cellera Inc. | Herring A.M.,Colorado School of Mines | And 8 more authors.
Energy and Environmental Science | Year: 2014

This article provides an up-to-date perspective on the use of anion-exchange membranes in fuel cells, electrolysers, redox flow batteries, reverse electrodialysis cells, and bioelectrochemical systems (e.g. microbial fuel cells). The aim is to highlight key concepts, misconceptions, the current state-of-the-art, technological and scientific limitations, and the future challenges (research priorities) related to the use of anion-exchange membranes in these energy technologies. All the references that the authors deemed relevant, and were available on the web by the manuscript submission date (30th April 2014), are included. © The Royal Society of Chemistry 2014.

Gao Y.,Tsinghua National Laboratory for Information Sciences and Technology | Wang M.,Hefei University of Technology | Tao D.,Intelligent Systems Technology, Inc. | Ji R.,Columbia University | Dai Q.,Tsinghua National Laboratory for Information Sciences and Technology
IEEE Transactions on Image Processing | Year: 2012

View-based 3-D object retrieval and recognition has become popular in practice, e.g., in computer aided design. It is difficult to precisely estimate the distance between two objects represented by multiple views. Thus, current view-based 3-D object retrieval and recognition methods may not perform well. In this paper, we propose a hypergraph analysis approach to address this problem by avoiding the estimation of the distance between objects. In particular, we construct multiple hypergraphs for a set of 3-D objects based on their 2-D views. In these hypergraphs, each vertex is an object, and each edge is a cluster of views. Therefore, an edge connects multiple vertices. We define the weight of each edge based on the similarities between any two views within the cluster. Retrieval and recognition are performed based on the hypergraphs. Therefore, our method can explore the higher order relationship among objects and does not use the distance between objects. We conduct experiments on the National Taiwan University 3-D model dataset and the ETH 3-D object collection. Experimental results demonstrate the effectiveness of the proposed method by comparing with the state-of-the-art methods. © 1992-2012 IEEE.

Chen D.-F.,Hefei University of Technology | Han Z.-Y.,Hefei University of Technology | Zhou X.-L.,Hefei University of Technology | Gong L.-Z.,Hefei University of Technology
Accounts of Chemical Research | Year: 2014

ConspectusAsymmetric catalysis has been considered to be the most intriguing means for building collections of functionalized optically active compounds. In particular, metal and organocatalysis have been well established to allow many fundamentally different reactions. Metal catalysis has enabled the participation of a much broader scope of chemical bonds in organic transformations than are allowed by organocatalysis, while organocatalysis permits a broader scope of functional groups to undergo a diverse range of enantioselective transformations, individually, simultaneously, or sequentially. Theoretically, the combination of organocatalysts and metal complexes could probably render new transformations through the simultaneous or sequential activation and reorganization of multiple chemical bonds if the superior features of both the catalysts are adopted.In 2001, both our research group and Takemotos group separately described an asymmetric allylation of glycine imino esters with allyl acetate catalyzed by palladium complexes and chiral ammonium salts. In these cases, the oxidative addition of palladium complexes to allyl acetate formed the π-Allylic fragments, while the chiral ammonium salts were actually responsible for controlling the stereoselectivity. These reactions in fact marked the beginning of asymmetric organo/metal combined catalysis. Since then, asymmetric organocatalysis combined with metal catalysis, including cooperative catalysis, relay catalysis, and sequential catalysis, has been a versatile concept for the creation of unknown organic transformations. Sequential catalysis describes a one-pot reaction involving two or more incompatible catalytic cycles. Alternatively, cooperative and relay catalyses require high compatibility of principally distinct catalysts and will be the focus of this Account. The catalysts in cooperative catalytic reactions must be able to simultaneously and individually activate both substrates to drive a bond-forming reaction, while relay catalysis is basically defined as a cascade process in which two or more sequential bond-forming transformations are independently catalyzed by distinct catalysts.In the past decade, we have discovered a variety of binary catalytic systems consisting of metals, including Rh(II), Pd(0), Au(I), and Mg(II), and chiral organocatalysts, including chiral phosphoric acids and quinine-based bifunctional molecules, for cooperative catalysis and relay catalysis, allowing the accomplishment of many unprecedented asymmetric transformations. In this Account, these achievements will be summarized, particularly focusing on the description of the concept and proof of the concept, to demonstrate the robustness of combined organo/metal catalysis in the creation of efficient enantioselective transformations.In addition, elegant studies from other laboratories using chiral phosphoric acid/Au(I) for the establishment of asymmetric cascade reactions involving the carbon-carbon triple bond functionality and typical combined organo/metal catalytic systems, very recently disclosed, will also be highlighted. © 2014 American Chemical Society.

Wang W.-G.,Hefei University of Technology | Wang W.-G.,National University of Singapore | He L.,Hefei University of Technology | Gong J.,National University of Singapore
Physical Review Letters | Year: 2012

The notion that decoherence rapidly reduces a superposition state to an incoherent mixture implicitly adopts a special representation, namely, the representation of preferred (pointer) states (PS). For weak or strong system-envrionment interaction, the behavior of PS is well known. Via a simple dynamical model that simulates a two-level system interacting with few other degrees of freedom as its environment, it is shown that even for intermediate system-environment coupling, approximate PS may still emerge from the coherent quantum dynamics of the whole system in the absence of any thermal averaging. The found PS can also continuously deform to expected limits for weak or strong system-environment coupling. Computational results are also qualitatively explained. The findings should be useful towards further understanding of decoherence and quantum thermalization processes. © 2012 American Physical Society.

Crespo J.,University of Michigan | Sun H.,Hefei University of Technology | Tian Z.,Hefei University of Technology | Zou W.,University of Michigan
Current Opinion in Immunology | Year: 2013

Human tumors progress despite the presence of tumor associated antigen (TAA)-specific T cells. Many different molecular and cellular mechanisms contribute to the failure of T cells to eradicate the tumor. These include immune suppressive networks that impair ongoing T cell function and enable tumor escape. Recent studies have started to reveal the nature of effector T cells in the tumor microenvironment. In this article we discuss T cell anergy, exhaustion, senescence, and stemness, and review the phenotype of dysfunctional T cell subsets and the underlying molecular mechanisms in the tumor microenvironments. We suggest that targeting T cell dysfunctional mechanisms and introducing/promoting T cell stemness are important approaches to treat patients with cancer. © 2012 Elsevier Ltd.

Wang P.-S.,Hefei University of Technology | Lin H.-C.,Hefei University of Technology | Zhai Y.-J.,Hefei University of Technology | Han Z.-Y.,Hefei University of Technology | Gong L.-Z.,Hefei University of Technology
Angewandte Chemie - International Edition | Year: 2014

The first enantioselective α-allylation of aldehydes with terminal alkenes has been realized by combining asymmetric counteranion catalysis and palladium-catalyzed allylic C-H activation. This method can tolerate a wide scope of α-branched aromatic aldehydes and terminal alkenes, thus affording allylation products in high yields and with good to excellent levels of enantioselectivity. Importantly, the findings suggest a new strategy for the future creation of enantioselective C-H/C-H coupling reactions. Go with the combo: The title reaction is realized by combining asymmetric counteranion catalysis and palladium-catalyzed allylic C-H activation. This method tolerates a wide scope of α-branched aromatic aldehydes and terminal alkenes, thus affording allylation products in high yields and with good to excellent levels of enantioselectivity. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Wen J.,Peking University | Chen X.,Hefei University of Technology
Bulletin of the Seismological Society of America | Year: 2012

The existence of f max has been perennially observed in various earthquakes. However, whether f max is caused by source processes (Papageorgiou and Aki, 1983) or site effects (Hanks, 1982) remains a controversial issue. With abundant near-fault strong ground-motion records, the Wenchuan earthquake provides an opportunity to validate the issue. By fitting the acceleration spectra of 10 seismic stations in the proximity of the fault on which the mainshock occurred, a set of f max values is obtained along the fault. The most notable feature of this set is its V-shaped distribution. The minimal f max value is recorded at the 051PXZ station near the epicenter, and f max increases as the distance deviates farther from the station. The maximal f max is recorded at the most northern station with respect to the epicenter. We estimate the cohesive zone size of the ruptured fault from the observed f max based on the source-cause model by Papageorgiou and Aki (1983). The sizes are remarkably consistent with the widths of the fault zone obtained from a totally independent study of the fault zone trapped waves (Li et al., 2009; Li et al., 2010). Therefore, the present study provides strong support to Papageorgiou and Aki's source-cause model for f max. Moreover, the V-shaped nonuni-form distribution of f max indicates a complicated rupture process of the Wenchuan earthquake, wherein the most energetic thrust faulting produces a thicker fault zone (approximately 400 m) around the epicenter, and an exhausted strike-slip faulting produces a thinner fault zone at the end portion of the fault (170-200 m).

Wang M.,Hefei University of Technology | Gao Y.,National University of Singapore | Lu K.,University of Chinese Academy of Sciences | Rui Y.,Microsoft
IEEE Transactions on Image Processing | Year: 2013

In view-based 3D object retrieval and recognition, each object is described by multiple views. A central problem is how to estimate the distance between two objects. Most conventional methods integrate the distances of view pairs across two objects as an estimation of their distance. In this paper, we propose a discriminative probabilistic object modeling approach. It builds probabilistic models for each object based on the distribution of its views, and the distance between two objects is defined as the upper bound of the Kullback-Leibler divergence of the corresponding probabilistic models. 3D object retrieval and recognition is accomplished based on the distance measures. We first learn models for each object by the adaptation from a set of global models with a maximum likelihood principle. A further adaption step is then performed to enhance the discriminative ability of the models. We conduct experiments on the ETH 3D object dataset, the National Taiwan University 3D model dataset, and the Princeton Shape Benchmark. We compare our approach with different methods, and experimental results demonstrate the superiority of our approach. © 2012 IEEE.

Wang M.,National University of Singapore | Wang M.,Hefei University of Technology | Ni B.,Advanced Digital Science Center | Hua X.-S.,Microsoft | Chua T.-S.,National University of Singapore
ACM Computing Surveys | Year: 2012

Along with the explosive growth of multimedia data, automatic multimedia tagging has attracted great interest of various research communities, such as computer vision, multimedia, and information retrieval. However, despite the great progress achieved in the past two decades, automatic tagging technologies still can hardly achieve satisfactory performance on real-world multimedia data that vary widely in genre, quality, and content. Meanwhile, the power of human intelligence has been fully demonstrated in the Web 2.0 era. If well motivated, Internet users are able to tag a large amount of multimedia data. Therefore, a set of new techniques has been developed by combining humans and computers for more accurate and efficient multimedia tagging, such as batch tagging, active tagging, tag recommendation, and tag refinement. These techniques are able to accomplish multimedia tagging by jointly exploring humans and computers in different ways. This article refers to them collectively as assistive tagging and conducts a comprehensive survey of existing research efforts on this theme. We first introduce the status of automatic tagging and manual tagging and then state why assistive tagging can be a good solution. We categorize existing assistive tagging techniques into three paradigms: (1) tagging with data selection&organization; (2) tag recommendation; and (3) tag processing. We introduce the research efforts on each paradigm and summarize the methodologies. We also provide a discussion on several future trends in this research direction. © 2012 ACM.

Tian Z.,Hefei University of Technology | Gershwin M.E.,University of California at Davis | Zhang C.,Shandong University
Journal of Autoimmunity | Year: 2012

As major components of innate immunity, NK cells not only exert cell-mediated cytotoxicity against tumor cells or infected cells, but also act to regulate the function of other immune cells by secretion of cytokines and chemokines, thus providing surveillance in early defense against viruses, intracellular bacteria and cancer cells. However, the effector function of NK cells must be exquisitely controlled in order to prevent inadvertent attack against self normal cells. The activity of NK cells is defined by integration of signals coming from inhibitory and activation receptors. Inhibitory receptors not only distinguish healthy from diseased cells by recognize self-MHC class I molecules on cell surfaces with "missing-self" model, but also provide an educational signal that generates functional NK cells. NK cells enrich in immunotolerance organ and recent findings of different regulatory NK cell subsets have indicated the unique role of NK cells in maintenance of homeostasis. Once the self-tolerance is broken, autoimmune response may occur. Although data has demonstrated that NK cells play important role in autoimmune disorders, NK cells seemed to act as a two edged weapon and play opposite roles with both regulatory and inducer activity even in the same disease. The precise role and regulatory mechanisms need to be further determined. In this review, we focus on recent research on the association of NK cells and antoimmune diseases, particularly the genetic correlation, the immune tolerance and misrecognition of NK cells, the regulatory function of NK cells, and their potential role in autoimmunity. © 2012 Elsevier Ltd.

Liu H.-C.,Shanghai University | Ren M.-L.,Hefei University of Technology | Wu J.,Tongji University | Lin Q.-L.,TU Berlin
International Journal of Production Research | Year: 2014

Nowadays selection of an optimal robot has become a challenging task for manufacturers with the increment of production demands and availability of more different robot models. Robot selection for a particular industrial application can be viewed as a complicated multi-criteria decision-making problem which requires consideration of a number of alternative robots and conflicting subjective and objective criteria. Furthermore, decision-makers tend to use multigranularity linguistic term sets to express their assessments on the subjective criteria, and there usually exists uncertain and incomplete assessment information. In this paper, an interval 2-tuple linguistic TOPSIS (ITL-TOPSIS) method is proposed to handle the robot selection problem under uncertain and incomplete information environment. This method considers both subjective judgements and objective information in real-life applications, and models the uncertainty and diversity of decision-makers assessments using interval 2-tuple linguistic variables. An example is cited for demonstrating the feasibility and practicability of the proposed method, and results show that the ITL-TOPSIS is an effective decision-making tool for robot evaluation and selection with uncertain and incomplete information. © 2013 Taylor & Francis.

He W.,Old Dominion University | Yan G.,University of Southern Indiana | Xu L.D.,Old Dominion University | Xu L.D.,CAS Institute of Computing Technology | And 2 more authors.
IEEE Transactions on Industrial Informatics | Year: 2014

The advances in cloud computing and internet of things (IoT) have provided a promising opportunity to resolve the challenges caused by the increasing transportation issues. We present a novel multilayered vehicular data cloud platform by using cloud computing and IoT technologies. Two innovative vehicular data cloud services, an intelligent parking cloud service and a vehicular data mining cloud service, for vehicle warranty analysis in the IoT environment are also presented. Two modified data mining models for the vehicular data mining cloud service, a Naïve Bayes model and a Logistic Regression model, are presented in detail. Challenges and directions for future work are also provided. © 2012 IEEE.

Gao Y.,Huazhong University of Science and Technology | Wang M.,Hefei University of Technology | Ji R.,Columbia University | Zha Z.,National University of Singapore | Shen J.,Singapore Management University
Information Sciences | Year: 2012

In many example-based information retrieval tasks, example query actually contains multiple sub-queries. For example, in 3D object retrieval, the query is an object described by multiple views. In content-based video retrieval, the query is a video clip that contains multiple frames. Without prior knowledge, the most intuitive approach is to treat the sub-queries equally without difference. In this paper, we propose a k-partite graph reinforcement approach to fuse these sub-queries based on the to-be-retrieved database. The approach first collects the top retrieved results. These results are regarded as pseudo-relevant samples and then a k-partite graph reinforcement is performed on these samples and the query. In the reinforcement process, the weights of the sub-queries are updated by an iterative process. We present experiments on 3D object retrieval and content-based video clip retrieval, and the results demonstrate that our method effectively boosts retrieval performance. © 2012 Elsevier Inc. All rights reserved.

Wang H.,Swinburne University of Technology | Kong H.,Hefei University of Technology | Man Z.,Swinburne University of Technology | Tuan D.M.,Swinburne University of Technology | And 2 more authors.
IEEE Transactions on Industrial Electronics | Year: 2014

In this paper, the modeling of steer-by-wire (SbW) systems is further studied, and a sliding mode control scheme for the SbW systems with uncertain dynamics is developed. It is shown that an SbW system, from the steering motor to the steered front wheels, is equivalent to a second-order system. A sliding mode controller can then be designed based on the bound information of uncertain system parameters, uncertain self-aligning torque, and uncertain torque pulsation disturbances, in the sense that not only the strong robustness with respect to large and nonlinear system uncertainties can be obtained but also the front-wheel steering angle can converge to the handwheel reference angle asymptotically. Both the simulation and experimental results are presented in support of the excellent performance and effectiveness of the proposed scheme. © 1982-2012 IEEE.

Ji R.,Xiamen University | Gao Y.,National University of Singapore | Hong R.,Hefei University of Technology | Liu Q.,Huazhong University of Science and Technology | And 2 more authors.
IEEE Transactions on Geoscience and Remote Sensing | Year: 2014

Hyperspectral image classification has attracted extensive research efforts in the recent decade. The main difficulty lies in the few labeled samples versus the high dimensional features. To this end, it is a fundamental step to explore the relationship among different pixels in hyperspectral image classification, toward jointly handing both the lack of label and high dimensionality problems. In the hyperspectral images, the classification task can be benefited from the spatial layout information. In this paper, we propose a hyperspectral image classification method to address both the pixel spectral and spatial constraints, in which the relationship among pixels is formulated in a hypergraph structure. In the constructed hypergraph, each vertex denotes a pixel in the hyperspectral image. And the hyperedges are constructed from both the distance between pixels in the feature space and the spatial locations of pixels. More specifically, a feature-based hyperedge is generated by using distance among pixels, where each pixel is connected with its K nearest neighbors in the feature space. Second, a spatial-based hyperedge is generated to model the layout among pixels by linking where each pixel is linked with its spatial local neighbors. Both the learning on the combinational hypergraph is conducted by jointly investigating the image feature and the spatial layout of pixels to seek their joint optimal partitions. Experiments on four data sets are performed to evaluate the effectiveness and and efficiency of the proposed method. Comparisons to the state-of-the-art methods demonstrate the superiority of the proposed method in the hyperspectral image classification. © 2013 IEEE.

Hu X.,Peking University | Gu Y.,Peking University | Gong Q.,Peking University | Guo G.,Hefei University of Technology
Physical Review A - Atomic, Molecular, and Optical Physics | Year: 2011

A Markovian dissipative quantum channel can generate quantum discord from some bipartite product states if and only if it cannot be reduced to individual decoherence channels independently acting on each qudit. As a byproduct, we also prove that proper individual decoherence can transform the classical correlation into quantum discord. Our result builds a tight connection between quantum discord and collective decoherence. © 2011 American Physical Society.

Bi Z.,Indiana University - Purdue University Fort Wayne | Xu L.D.,CAS Institute of Computing Technology | Xu L.D.,Shanghai JiaoTong University | Xu L.D.,Hefei University of Technology | And 2 more authors.
IEEE Transactions on Industrial Informatics | Year: 2014

Design and operation of a manufacturing enterprise involve numerous types of decision-making at various levels and domains. A complex system has a large number of design variables and decision-making requires real-time data collected from machines, processes, and business environments. Enterprise systems (ESs) are used to support data acquisition, communication, and all decision-making activities. Therefore, information technology (IT) infrastructure for data acquisition and sharing affects the performance of an ES greatly. Our objective is to investigate the impact of emerging Internet of Things (IoT) on ESs in modern manufacturing. To achieve this objective, the evolution of manufacturing system paradigms is discussed to identify the requirements of decision support systems in dynamic and distributed environments; recent advances in IT are overviewed and associated with next-generation manufacturing paradigms; and the relation of IT infrastructure and ESs is explored to identify the technological gaps in adopting IoT as an IT infrastructure of ESs. The future research directions in this area are discussed. © 2012 IEEE.

Gao Y.,Tsinghua University | Wang M.,Hefei University of Technology | Zha Z.-J.,National University of Singapore | Shen J.,Singapore Management University | And 3 more authors.
IEEE Transactions on Image Processing | Year: 2013

Due to the popularity of social media websites, extensive research efforts have been dedicated to tag-based social image search. Both visual information and tags have been investigated in the research field. However, most existing methods use tags and visual characteristics either separately or sequentially in order to estimate the relevance of images. In this paper, we propose an approach that simultaneously utilizes both visual and textual information to estimate the relevance of user tagged images. The relevance estimation is determined with a hypergraph learning approach. In this method, a social image hypergraph is constructed, where vertices represent images and hyperedges represent visual or textual terms. Learning is achieved with use of a set of pseudo-positive images, where the weights of hyperedges are updated throughout the learning process. In this way, the impact of different tags and visual words can be automatically modulated. Comparative results of the experiments conducted on a dataset including 370+images are presented, which demonstrate the effectiveness of the proposed approach. © 1992-2012 IEEE.

Bian Y.,Shanghai University | Yang F.,Hefei University of Technology
Energy Policy | Year: 2010

Data envelopment analysis (DEA) has been widely used in energy efficiency and environment efficiency analysis in recent years. Based on the existing environment DEA technology, this paper presents several DEA models for estimating the aggregated efficiency of resource and environment. These models can evaluate DMUs' energy efficiencies and environment efficiencies simultaneously. However, efficiency ranking results obtained from these models are not the same, and each model can provide some valuable information of DMUs' efficiencies, which we could not ignore. Under this situation, it may be hard for us to choose a specific model in practice. To address this kind of performance evaluation problem, the current paper extends Shannon-DEA procedure to establish a comprehensive efficiency measure for appraising DMUs' resource and environment efficiencies. In the proposed approach, the measure for evaluating a model's importance degree is provided, and the targets setting approach of inputs/outputs for DMU managers to improve DMUs' energy and environmental efficiencies is also discussed. We illustrate the proposed approach using real data set of 30 provinces in China. © 2009 Elsevier Ltd. All rights reserved.

Ren H.,Hefei University of Technology | Chen X.,Hefei University of Technology | Huang Q.,Peking University
Geophysical Journal International | Year: 2012

The electrokinetic effect is one mechanism that causes the coupling between seismic and electromagnetic energies. This study deals with the numerical simulation of the electrokinetically induced coseismic electromagnetic fields associated with seismic waves created by a finite faulting in porous media. The key point of our numerical technique is to combine the point source stacking method with the Luco-Apsel-Chen generalized reflection and transmission method. After some validation test of our simulation method, we show several numerical simulation examples. Through a near-field model, we show that the point source approximation is not accurate in this configuration, as well as that the position of the rupture starting point and rupture speed obviously affect the coseismic EM fields. Then we numerically investigate the influence of different media properties on seismic waves and coseismic EM fields. We also carry out simulations of multilayer half-space models and show the characteristics of the coseismic EM fields. The preliminary results indicate that our numerical technique provides an effective approach of studying coseismic electromagnetic fields associated with seismic waves due to a finite faulting in porous media. © 2012 The Authors Geophysical Journal International © 2012 RAS.

Zhou Q.Q.,Hefei University of Technology | Chen X.Y.,Hefei University of Technology | Wang B.,China Building Materials Industry Geological Exploration Center Anhui Branch
Microporous and Mesoporous Materials | Year: 2012

In this work, we demonstrate a simple and effective carbonization method to prepare porous carbon without any activation process, using calcium citrate as carbon source. The carbon products were well characterized by means of thermogravimetric analysis, X-ray diffraction pattern, field emission scanning electron microscopy and BET surface area measurement. It is found out that the carbonization temperature plays a crucial effect on the structures and electrochemical properties of the carbons. Because of the coexistence of major amount of mesopores and minor micropores towards the carbon at 700 °C, the sequences of capacitance values are: 700 °C > 800 °C > 600 °C. As a result, the maximum specific capacitance of the carbon at 700 °C reaches as much as 172 F g -1 at the current density of 1 mA cm -2, which corresponds to a BET surface area of 1072 m 2 g -1, also confirming the nonlinear relationship between the specific surface area and the capacitance. Meanwhile, the maximum energy density and power density of the carbon at 700 °C are 24 Wh kg -1 and 6.7 kW kg -1, respectively. Owing to the high specific capacitance and good cycle stability, the present carbons are excellent electrode materials for high-rate electrochemical capacitors. © 2012 Elsevier Inc. All rights reserved.

Zhu S.,Hefei University of Technology | Wang Y.,Hefei University | Shi M.,Anhui University
IEEE Transactions on Information Theory | Year: 2010

In this paper, we investigate the structure and properties of cyclic codes over the ring F2+vF2. We first study the relationship between cyclic codes over F2+vF2 and binary cyclic codes. Then we prove that cyclic codes over the ring are principally generated, and give the generator polynomial of cyclic codes over the ring. Finally, we obtain the unique idempotent generators for cyclic codes of odd length and determine the number of cyclic codes for a given length ν over F2+vF 2. © 2006 IEEE.

Zhang W.,Hefei University of Technology | Zhang X.,Shanghai University | Wang S.,Shanghai University
IEEE Transactions on Information Theory | Year: 2010

High-performance steganography requires large embedding rate and small distortion, i.e., high embedding efficiency. Steganographic codes (stego-codes) derived from covering codes can improve embedding efficiency. In this paper, a new method is proposed to construct binary stego-codes for LSB embedding in gray-scale signals, which shows that not just one but a family of stego-codes can be generated from a covering code by combining Hamming codes and wet paper codes. This method can greatly expand the set of embedding schemes as applied to steganography. Performances of stego-code families (SCF) of structured codes and random codes are analyzed. SCFs of random codes can approach the rate-distortion bound on LSB embedding for any chosen embedding rate. Furthermore, SCFs are modified for applications in ±1 embedding, and a treble layered embedding method for ±2 embedding is obtained. By combining the modified SCFs and the treble layered method, a near-optimal scheme for ±2 embedding is presented. © 2006 IEEE.

Li C.-F.,Hefei University of Technology | Xu J.-S.,Hefei University of Technology | Xu X.-Y.,Hefei University of Technology | Li K.,National University of Singapore | Guo G.-C.,Hefei University of Technology
Nature Physics | Year: 2011

The uncertainty principle, which bounds the uncertainties involved in obtaining precise outcomes for two complementary variables defining a quantum particle, is a crucial aspect in quantum mechanics. Recently, the uncertainty principle in terms of entropy has been extended to the case involving quantum entanglement. With previously obtained quantum information for the particle of interest, the outcomes of both non-commuting observables can be predicted precisely, which greatly generalizes the uncertainty relation. Here, we experimentally investigated the entanglement-assisted entropic uncertainty principle for an entirely optical set-up. The uncertainty is shown to be near zero in the presence of quasi-maximal entanglement. The new uncertainty relation is further used to witness entanglement. The verified entropic uncertainty relation provides an intriguing perspective in that it implies the uncertainty principle is not only observable-dependent but is also observer-dependent. © 2011 Macmillan Publishers Limited. All rights reserved.

Wang Y.-Q.,Hefei University of Technology | Wang L.-J.,Anhui Water Conservancy Technical College
Yantu Lixue/Rock and Soil Mechanics | Year: 2014

Soilbags have been understood to be cheap and easy to acquire as well as vibration reduction. However, the research on the effect of soilbag vibration reduction is only based on test results at present; the mechanism of it has rarely been studied. Based on the principle of soilbag energy dissipation, the discrete element method is used to build energy dissipation equation during the process of soilbag vibration reduction. Firstly, using the discrete element method to establish every part of soilbag energy dissipation equations, through numerical simulation of a single soilbag under simple vertical loading condition, from energy conservation perspective to verify that the calculation of each part of the energy is reasonable; meanwhile, the correctness of the established equations of energy dissipation is proved; and then energy dissipation of a single soilbag is simulated from quantitative perspective by using the verified energy dissipation equation under the cyclic loading rate of 1 000 N/s three times. The numerical simulation results show that the percentage of total soilbag and its inside particles energy consumption exhibit obvious wavy shaped fluctuating with loading and unloading; the percentage of it is over 75% of the total energy; this means soilbag can play a good effect on energy dissipation.

Agency: European Commission | Branch: H2020 | Program: FCH2-RIA | Phase: FCH-04.3-2014 | Award Amount: 1.51M | Year: 2015

The aim of the HySEA project is to conduct pre-normative research on vented deflagrations in enclosures and containers for hydrogen energy applications. The ambition is to facilitate the safe and successful introduction of hydrogen energy systems by introducing harmonized standard vent sizing requirements. The partners in the HySEA consortium have extensive experience from experimental and numerical investigations of hydrogen explosions. The experimental program features full-scale vented deflagration experiments in standard ISO containers, and includes the effect of obstacles simulating levels of congestion representative of industrial systems. The project also entails the development of a hierarchy of predictive models, ranging from empirical engineering models to sophisticated computational fluid dynamics (CFD) and finite element (FE) tools. The specific objectives of HySEA are: - To generate experimental data of high quality for vented deflagrations in real-life enclosures and containers with congestion levels representative of industrial practice; - To characterize different strategies for explosion venting, including hinged doors, natural vent openings, and commercial vent panels; - To invite the larger scientific and industrial safety community to submit blind-predictions for the reduced explosion pressure in selected well-defined explosion scenarios; - To develop, verify and validate engineering models and CFD-based tools for reliable predictions of pressure loads in vented explosions; - To develop and validate predictive tools for overpressure (P) and impulse (I), and produce P-I diagrams for typical structures with relevance for hydrogen energy applications; - To use validated CFD codes to explore explosion hazards and mitigating measures in larger enclosures, such as warehouses; and - To formulate recommendations for improvements to European (EN-14994), American (NFPA 68), and other relevant standards for vented explosions.

Wang M.,China Institute of Technology | Wang Z.L.,Hefei University of Technology
Applied Mechanics and Materials | Year: 2014

Clamping fixture of active fixing-board plays an important role on vibration experiment. In this paper, the clamping fixture for active fixing-board is designed based on fixture theory. Modal characteristic of the fixture designed is analyzed using finite element software ANSYS. Research shows that the requirement of the vibration experiment on active fixing-board can be met completely by the fixture designed in this paper. © (2014) Trans Tech Publications, Switzerland.

Fu C.,Hefei University of Technology | Yang S.-L.,Key Laboratory of Process Optimization and Intelligent Decision making
Expert Systems with Applications | Year: 2011

To combine interval-valued belief structures (IBSs), it is necessary to investigate the applicability of Dempsters rule to know whether Dempsters rule is adequate to be used and whether other alternatives are needed. This makes it significant to investigate IBSs pairwise relationships (IPRs) since they have an important impact on the applicability of Dempsters rule to the combination of two IBSs. IPRs can be constructed based on beliefs pairwise relationships (BPRs), so this paper proposes a consistency measure to quantitatively divide BPRs into three categories. Using a consistency interval between two IBSs that is obtained by solving a pair of optimization problems constructed based on the consistency measure, IPRs are quantified and divided into six categories on the basis of BPRs. According to IPRs, the applicability of Dempsters rule to the combination of two IBSs is recommended. Finally, the applicability of Dempsters rule to the combination of multiple IBSs is investigated. © 2010 Elsevier Ltd. All rights reserved.

Fu C.,Hefei University of Technology | Fu C.,Key Laboratory of Process Optimization and Intelligent Decision making | Chin K.-S.,City University of Hong Kong
Knowledge-Based Systems | Year: 2014

In multiple attribute decision making (MADM), different attribute weights may generate different solutions, which means that attribute weights significantly influence solutions. When there is a lack of sufficient data, knowledge, and experience for a decision maker to generate attribute weights, the decision maker may expect to find the most satisfactory solution based on unknown attribute weights called a robust solution in this study. To generate such a solution, this paper proposes a robust evidential reasoning (ER) approach to compare alternatives by measuring their robustness with respect to attribute weights in the ER context. Alternatives that can become the best with the support of one or more sets of attribute weights are firstly identified. The measurement of robustness of each identified alternative from two perspectives, i.e., the optimal situation of the alternative and the insensitivity of the alternative to a variation in attribute weights is then presented. The procedure of the proposed approach is described based on the combination of such identification of alternatives and the measurement of their robustness. A problem of car performance assessment is investigated to show that the proposed approach can effectively produce a robust solution to a MADM problem with unknown attribute weights. © 2014 Elsevier B.V. All rights reserved.

Liu X.-W.,Hefei University of Technology | Zhou S.,KTH Royal Institute of Technology
International Journal of Modern Physics A | Year: 2013

The Daya Bay and RENO reactor neutrino experiments have revealed that the smallest neutrino mixing angle is in fact relatively large, i.e. θ13 ≈9°. Motivated by this exciting progress, we perform a systematic study of the neutrino mass matrix Mν with one or two texture zeros, in the assumption that neutrinos are Dirac particles. Among 15 possible patterns with two texture zeros, only three turn out to be favored by current neutrino oscillation data at the 3σ level. Although all the six patterns with one texture zero are compatible with the experimental data at the 3σ level, the parameter space of each pattern is strictly constrained. Phenomenological implications of Mν on the leptonic CP violation and neutrino mass spectrum are explored, and the stability of texture zeros against the radiative corrections is also discussed. © 2013 World Scientific Publishing Company.

Lv J.-P.,Anhui Normal University | Chen G.,Fudan University | Chen G.,University of Toronto | Deng Y.,Hefei University of Technology | Meng Z.Y.,CAS Institute of Physics
Physical Review Letters | Year: 2015

Employing large-scale quantum Monte Carlo simulations, we reveal the full phase diagram of the extended Hubbard model of hard-core bosons on the pyrochlore lattice with partial fillings. When the intersite repulsion is dominant, the system is in a cluster Mott insulator phase with an integer number of bosons localized inside the tetrahedral units of the pyrochlore lattice. We show that the full phase diagram contains three cluster Mott insulator phases with 1/4, 1/2, and 3/4 boson fillings, respectively. We further demonstrate that all three cluster Mott insulators are Coulomb liquid phases and its low-energy property is described by the emergent compact U(1) quantum electrodynamics. In addition to measuring the specific heat and entropy of the cluster Mott insulators, we investigate the correlation function of the emergent electric field and verify it is consistent with the compact U(1) quantum electrodynamics description. Our result sheds light on the magnetic properties of various pyrochlore systems, as well as the charge physics of the cluster magnets. © 2015 American Physical Society. © 2015 American Physical Society.

Fan H.,Shanghai JiaoTong University | Fan H.,Hefei University of Technology | Hu L.,Jiangxi Normal University
Frontiers of Physics | Year: 2012

By virtue of the new technique of performing integration over Dirac's ket-bra operators, we explore quantum optical version of classical optical transformations such as optical Fresnel transform, Hankel transform, fractional Fourier transform, Wigner transform, wavelet transform and Fresnel-Hadmard combinatorial transform etc. In this way one may gain benefit for developing classical optics theory from the research in quantum optics, or vice-versa. We cannot only find some new quantum mechanical unitary operators which correspond to the known optical transformations, deriving a new theorem for calculating quantum tomogram of density operators, but also can reveal some new classical optical transformations. For examples, we find the generalized Fresnel operator (GFO) to correspond to the generalized Fresnel transform (GFT) in classical optics. We derive GFO's normal product form and its canonical coherent state representation and find that GFO is the loyal representation of symplectic group multiplication rule. We show that GFT is just the transformation matrix element of GFO in the coordinate representation such that two successive GFTs is still a GFT. The ABCD rule of the Gaussian beam propagation is directly demonstrated in the context of quantum optics. Especially, the introduction of quantum mechanical entangled state representations opens up a new area in finding new classical optical transformations. The complex wavelet transform and the condition of mother wavelet are studied in the context of quantum optics too. Throughout our discussions, the coherent state, the entangled state representation of the two-mode squeezing operators and the technique of integration within an ordered product (IWOP) of operators are fully used. All these have confirmed Dirac's assertion: "... for a quantum dynamic system that has a classical analogue, unitary transformation in the quantum theory is the analogue of contact transformation in the classical theory". © 2012 Higher Education Press and Springer-Verlag Berlin Heidelberg.

Zhong M.-C.,Hefei University of Technology | Wei X.-B.,Hefei University of Technology | Wei X.-B.,Shanghai JiaoTong University | Zhou J.-H.,Hefei University of Technology | And 2 more authors.
Nature Communications | Year: 2013

The recent development of non-invasive imaging techniques has enabled the visualization of molecular events underlying cellular processes in live cells. Although microscopic objects can be readily manipulated at the cellular level, additional physiological insight is likely to be gained by manipulation of cells in vivo, which has not been achieved so far. Here we use infrared optical tweezers to trap and manipulate red blood cells within subdermal capillaries in living mice. We realize a non-contact micro-operation that results in the clearing of a blocked microvessel. Furthermore, we estimate the optical trap stiffness in the capillary. Our work expands the application of optical tweezers to the study of live cell dynamics in animals. © 2013 Macmillan Publishers Limited. All rights reserved.

Li Z.,Shanghai JiaoTong University | Kang Y.,Hefei University of Technology
Automatica | Year: 2010

The hybrid joints can be switched to either active (actuated) or passive (under-actuated) mode as needed (Li, Ming, Xi, & Shimojo, 2006), in this paper, dynamic coupling switching control incorporating Support Vector Machines (SVMs) is developed for wheeled mobile manipulators with hybrid joints. The hybrid actuated robot dynamics is a mixed under-actuated and actuated model. In order to approximate the high dimension unmodelled dynamics, the SVMs matrix and its operator are proposed. Considering the joint switching as an event, the event driven switching control strategy is used to ensure that the system outputs track the given bounded reference signals within a small neighborhood of zero, and guarantee semi-global uniform boundedness of all closed loop signals, and the switch stability. The effectiveness of the proposed controls is verified through extensive simulations. © 2010 Elsevier Ltd. All rights reserved.

Li G.,CAS South China Sea Institute of Oceanology | Du Y.,CAS South China Sea Institute of Oceanology | Xu H.,Nanjing University of Information Science and Technology | Ren B.,Hefei University of Technology
Journal of Climate | Year: 2015

An excessive cold tongue error in the equatorial Pacific has prevailed in several generations of climatemodels. However, the causes of this problemremain amystery, partly owing to uncertainty and/or a lack of observational datasets. Based on the multimodel ensemble from phase 5 of the Coupled Model Intercomparison Project (CMIP5), this study introduces a novel intermodel approach to identify the bias source by going beyond comparison with observational datasets. Intermodel statistics show that the excessive cold tongue bias could be traced back to a too strong oceanic dynamic cooling linked to a too shallow thermocline along the equatorial Pacific. A heat budget analysis suggests that the excessive oceanic dynamic cooling is balanced by the surface latent heat flux (LHF) adjustment. This is consistent with a variety of oceanic and atmospheric observations but at odds with the popular objectively analyzed air-sea heat fluxes (OAFlux) products. Further analyses suggest an alarming overestimation of OAFlux net surface heat flux (Qnet) into the tropical Pacific, mainly ascribed to observational uncertainly in air specific humidity. Implications for intermodel statistics in assessing model processes, validating observational data, and regulating future climate projections are discussed. © 2015 American Meteorological Society.

Luo H.,Applied Technology Internet | Du B.,Hefei University of Technology | Huang G.Q.,Applied Technology Internet | Chen H.,Hefei University of Technology | Li X.,Hefei University of Technology
International Journal of Production Economics | Year: 2013

Hybrid flow shop (HFS) scheduling has been extensively examined and the main objective has been to improve production efficiency. However, limited attention has been paid to the consideration of energy consumption with the advent of green manufacturing. This paper proposes a new ant colony optimization (MOACO) meta-heuristic considering not only production efficiency but also electric power cost (EPC) with the presence of time-of-use (TOU) electricity prices. The solution is encoded as a permutation of jobs. A list schedule algorithm is applied to construct the sequence by artificial ants and generate a complete schedule. A right-shift procedure is then used to adjust the start time of operations aiming to minimize the EPC for the schedule. In terms of theoretical research aspect, the results from computational experiments indicate that the efficiency and effectiveness of the proposed MOACO are comparable to NSGA-II and SPEA2. In terms of practical application aspect, the guideline about how to set preference over multiple objectives has been studied. This result has significant managerial implications in real life production. The parameter analysis also shows that durations of TOU periods and processing speed of machines have great influence on scheduling results as longer off-peak period and use of faster machines provide more flexibility for shifting high-energy operations to off-peak periods. © 2013 Elsevier B.V.

Li Z.,Shanghai JiaoTong University | Li J.,Shanghai JiaoTong University | Kang Y.,Hefei University of Technology
Automatica | Year: 2010

In this paper, we consider multiple mobile manipulators grasping a common object in contact with a rigid surface, and propose a new version of adaptive robust control extended to the actuator level for multiple mobile manipulators carrying a common object in a cooperative manner. The proposed controls are robust not only to parametric uncertainties including mass variation and electrical parameters but also to external disturbances. Simulation results are presented to validate that the motion/force tracking errors converge to zero whereas the internal force tracking error remains bounded and can be made arbitrarily small. © 2010 Elsevier Ltd. All rights reserved.

Cui C.,TU Berlin | Gan L.,TU Berlin | Li H.-H.,Hefei University of Technology | Yu S.-H.,Hefei University of Technology | And 2 more authors.
Nano Letters | Year: 2012

We demonstrate how shape selectivity and optimized surface composition result in exceptional oxygen reduction activity of octahedral PtNi nanoparticles (NPs). The alloy octahedra were obtained by utilizing a facile, completely surfactant-free solvothermal synthesis. We show that the choice of precursor ligands controls the shape, while the reaction time tunes the surface Pt:Ni composition. The 9.5 nm sized PtNi octahedra reached a 10-fold surface area-specific (∼3.14 mA/cmPt2) as well as an unprecedented 10-fold Pt mass based (∼1.45 A/mgPt) activity gain over the state-of-art Pt electrocatalyst, approaching the theoretically predicted limits. © 2012 American Chemical Society.

Wu L.,Harbin Institute of Technology | Ling J.,University of Notre Dame | Wu Z.-Q.,Hefei University of Technology
Advanced Synthesis and Catalysis | Year: 2011

We report here the first dendritic phosphine-stabilized nickel nanoparticles, which can be prepared from nickel(II) chloride, a third generation phosphine dendrimer and the surfactant tetraoctylammonium bromide (TOABr) by two-phase reduction using sodium borohydride. The resulting nickel nanoparticles are found to be a highly active and recyclable catalyst for Suzuki coupling reactions, especially those extended to aryl chloride substrates, affording the biaryls in moderate to good yields. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Fu C.,Hefei University of Technology | Yang S.,Key Laboratory of Process Optimization and Intelligent Decision Making
Knowledge-Based Systems | Year: 2012

This paper proposes a method to reach required group consensus (GC) and find GC-based solutions to multiple attribute group decision analysis (MAGDA) problems using interval-valued belief structures (IBSs) based on evidential reasoning approach. The GC at the attribute, alternative and global levels is constructed based on IBSs. Subjective weights of experts, weights of attributes, and utilities of experts for assessment grades are extended to intervals. Hereinto, the former two can be characterized by four kinds of relevant constraints, and combined with the constraints to be incorporated into the optimization problems for the GC. Also, utilities of experts for assessment grades with the consistent combination of relevant constraints and their intrinsic constraint contribute to the GC. Further, a strategy for experts to renew assessments is designed to improve the GC. A preferentially developed industry selection problem is solved by the proposed method to demonstrate its detailed implementation process, and its validity and applicability. © 2012 Elsevier B.V. All rights reserved.

Wang J.-P.,Hefei University of Technology | Wang J.-P.,University of Illinois at Urbana - Champaign | Yuan S.-J.,Hefei University of Technology | Wang Y.,University of Illinois at Urbana - Champaign | Yu H.-Q.,Hefei University of Technology
Water Research | Year: 2013

Flocculation process is one of the most widely used techniques for water and wastewater treatment, and also for sludge dewatering. Synthesis of natural biopolymers or modification of natural biopolymers as environmentally friendly flocculants is highly desired in the field of environmental protection. In this work, a water soluble copolymer flocculant, STC-g-PDMC (starch-graft-poly (2-methacryloyloxyethyl) trimethyl ammonium chloride) was synthesized through grafting a monomer, (2-methacryloyloxyethyl) trimethyl ammonium chloride (DMC), onto starch initiated by potassium persulphate. Acetone and ethanol were used for copolymer precipitation and purification in the synthesis, which diminished the toxicity during the synthesis process. The graft copolymer was characterized using Fourier-transform infrared spectroscopy, 1H nuclear magnetic resonance, X-ray powder diffraction, thermogravimetric analysis and elemental analysis. The prepared STC-g-PDMC exhibited a highly effective flocculation capability for kaolin suspensions compared with starch and polyacrylamide as control. The charge neutralization effect played an important role in the flocculation process at low flocculant dosages. When it was used as dewatering agent for anaerobic sludge, the conditioned sludge could be easily filtered after the dosage reached 0.696% of the dry weight of sludge. Such a graft copolymer is a promising green agent for wastewater treatment and sludge dewatering applications. © 2013 Elsevier Ltd.

News Article | February 15, 2017
Site: www.eurekalert.org

The first ever evidence of live birth in an animal group previously thought to lay eggs exclusively has been discovered by an international team of scientists, including a palaeontologist from the University of Bristol. The remarkable 250 million-year-old fossil from China shows an embryo inside the mother. Live birth is well known in mammals, where the mother has a placenta to nourish the developing embryo. It is also very common among lizards and snakes, where the babies sometimes 'hatch' inside their mother and emerge without a shelled egg. Until recently, the third major group of living land vertebrates, the crocodiles and birds, part of the wider group Archosauromorpha, only laid eggs. Egg laying is the primitive state, seen at the base of reptiles, and in their ancestors such as amphibians and fishes. The new fossil is an unusual, long-necked animal called Dinocephalosaurus, an archosauromorph that flourished in shallow seas of South China in the Middle Triassic. It was a fish-eater, snaking its long neck from side to side to snatch its prey. The embryo is inside the rib cage of the mother, and it faces forward. Swallowed animals generally face backward because the predator swallows its prey head-first to help it go down its throat. Furthermore, the small reptile inside the mother is an example of the same species. Lead study author, Professor Jun Liu from Hefei University of Technology in China, said: "We were so excited when we first saw this embryonic specimen several years ago but we were not sure if the embryonic specimen is the last lunch of the mother or its unborn baby. "Upon further preparation and closer inspection, we realised that something unusual has been discovered. "Further evolutionary analysis reveals the first case of live birth in such a wide group containing birds, crocodilians, dinosaurs and pterosaurs among others, and pushes back evidence of reproductive biology in the group by 50 million years. "Information on reproductive biology of archosauromorphs before the Jurassic period was not available until our discovery, despite a history of 260 million years." Evolutionary analysis shows that this instance of live birth was also associated with genetic sex determination. Professor Chris Organ, another author from Montana State University, added: "Some reptiles today, such as crocodiles, determine the sex of their offspring by the temperature inside the nest. "We identified that Dinocephalosaurus, a distant ancestor of crocodiles, determined the sex of its babies genetically, like mammals and birds." This new specimen from China rewrites our understanding of the evolution of reproductive systems. Professor Mike Benton, another co-author from the School of Earth Sciences at the University of Bristol, said: "The analysis of the evolutionary position of the new specimens shows there is no fundamental reason why archosauromorphs could not have evolved live birth "This combination of live birth and genotypic sex determination seems to have been necessary for animals such as Dinocephalosaurus to become aquatic. It's great to see such an important step forward in our understanding of the evolution of a major group coming from a chance fossil find in a Chinese field." This piece of work is part of wider collaborations between palaeontologists in China, the United States, the UK and Australia.

News Article | February 15, 2017
Site: www.eurekalert.org

A remarkable 250 million-year-old "terrible-headed lizard" fossil found in China shows an embryo inside the mother -- clear evidence for live birth. Head of The University of Queensland's School of Earth and Environmental Sciences and co-author Professor Jonathan Aitchison said the fossil unexpectedly provided the first evidence for live birth in an animal group previously thought to exclusively lay eggs. "Live birth is well known in mammals, where the mother has a placenta to nourish the developing embryo," Professor Aitchison said. "Live birth is also very common among lizards and snakes, where the babies sometimes 'hatch' inside their mother and emerge without a shelled egg." Until recently it was thought the third major group of living land vertebrates, the crocodiles and birds (part of the wider group Archosauromorpha) only laid eggs. "Indeed, egg-laying is the primitive state, seen at the base of reptiles, and in their ancestors such as amphibians and fishes," Professor Aitchison said. He said the new fossil was an unusual, long-necked marine animal called an archosauromorph that flourished in shallow seas of South China in the Middle Triassic Period. The creature was a fish-eater, snaking its long neck from side to side to snatch its prey. Its fossil was one of many astonishingly well-preserved specimens from new "Luoping biota" locations in south-western China. There were no known fossils like this (marine vertebrates of this age) from Australia. Lead author Professor Jun Liu from Hefei University of Technology China, said the researchers were "excited" when they first saw this embryonic specimen. "We were not sure if the embryonic specimen was the mother's last lunch or its unborn baby," Professor Liu said. "Upon further preparation and closer inspection, we discovered something unusual." He said the embryo was inside the mother's rib cage, and it faced forward; swallowed animals generally face backward because the predator swallows its prey head-first to help it go down its throat. Furthermore, the small reptile inside the mother was an example of the same species. "Further evolutionary analysis revealed the first case of live birth in such a wide group containing birds, crocodilians, dinosaurs and pterosaurs among others, and pushes back evidence of reproductive biology in the group by 50 million years," Professor Liu said. "Information on reproductive biology of archosauromorphs before the Jurassic Period was not available until our discovery, despite a 260 million-year history of the group." Professor Chris Organ from Montana State University said evolutionary analysis showed that this instance of live birth was also associated with genetic sex determination. "Some reptiles today, such as crocodiles, determine the sex of their offspring by the temperature inside the nest," he said. "We identified that Dinocephalosaurus, a distant ancestor of crocodiles, determined the sex of its babies genetically, like mammals and birds. "This new specimen from China rewrites our understanding of the evolution of reproductive systems." Professor Mike Benton of the University of Bristol said analysis of the evolutionary position of the new specimens showed no fundamental reason why archosauromorphs could not have evolved live birth. "This combination of live birth and genotypic sex determination seems to have been necessary for animals such as Dinocephalosaurus to become aquatic," he said. "It's great to see such an important step forward in our understanding of the evolution of a major group coming from a chance fossil find in a Chinese field." The work is part of ongoing wider collaborations between palaeontologists in China, the United States, the UK and Australia. The paper is published in the journal, Nature Communications.

Du H.,Hefei University of Technology | Du H.,Nanjing Southeast University | Li S.,Nanjing Southeast University
Automatica | Year: 2014

To solve the problem of attitude synchronization for a group of flexible spacecraft during formation maneuvers, a distributed attitude cooperative control strategy is investigated in this paper. Based on the backstepping design and the neighbor-based design rule, a distributed attitude control law is constructed step by step. Using cascaded systems' theory and graph theory, it is shown that the attitude synchronization is achieved asymptotically and the induced vibrations by flexible appendages are simultaneously suppressed under the proposed control law. © 2013 Elsevier Ltd. All rights reserved.

Shi F.,Hefei University of Technology | Kong X.,Hefei University of Technology | Wang P.,Hefei University of Technology | Kong F.,Hefei University of Technology | And 3 more authors.
Nature Physics | Year: 2013

Single-molecule nuclear magnetic resonance is a current challenge in the field of magnetic resonance spectroscopy and has important applications in chemical analysis and quantum computing. Through decoherence measurements of nitrogen-vacancy centres under dynamical decoupling control, the sensing of a single 13 C nuclear spin at nanometre distance has recently been realized. A further step towards the ultimate goal of structure analysis of single molecules would be the direct measurement of the interactions within single nuclear-spin clusters. Here we sense a single 13 C- 13 C nuclear-spin dimer located about 1 €‰nm from the nitrogen-vacancy centre and characterize the interaction (1/4690 Hz) between the two nuclear spins. From the measured interaction we derive the spatial configuration of the dimer with atomic-scale resolution. These results indicate that, in combination with advanced material-surface engineering, central spin decoherence under dynamical decoupling control may be a useful probe for nuclear magnetic resonance single-molecule structure analysis. © 2014 Macmillan Publishers Limited. All rights reserved.

He W.,Hefei University of Technology | Zhou J.,Hefei University of Technology | Chen C.,Hong Kong University of Science and Technology | Ji J.,Hefei University of Technology
Energy Conversion and Management | Year: 2014

This paper presents theoretical and experimental investigations of the winter operation mode of a thermoelectric cooling and heating system driven by a heat pipe photovoltaic/thermal (PV/T) panel. And the energy and exergy analysis of this system in summer and winter operation modes are also done. The winter operation mode of this system is tested in an experimental room which temperature is controlled at 18 °C. The results indicate the average coefficient of performance (COP) of thermoelectric module of this system can be about 1.7, the electrical efficiency of the PV/T panel can reach 16.7%, and the thermal efficiency of this system can reach 23.5%. The energy and exergy analysis show the energetic efficiency of the system in summer operation mode is higher than that of it in winter operation mode, but the exergetic efficiency in summer operation mode is lower than that in winter operation mode, on the contrary. © 2014 Elsevier Ltd. All rights reserved.

Xue P.,Nanjing Southeast University | Qin H.,Nanjing Southeast University | Tang B.,Nanjing Southeast University | Sanders B.C.,Hefei University of Technology | Sanders B.C.,University of Calgary
New Journal of Physics | Year: 2014

We realize the quasi-periodic dynamics of a quantum walker over 2.5 quasi-periods by realizing the walker as a single photon passing through a quantum-walk optical-interferometer network. We introduce fully controllable polarization-independent phase shifters in each optical path to realize arbitrary site-dependent phase shifts, and employ large clear-aperture beam displacers, while maintaining high-visibility interference, to enable 10 quantum-walk steps to be reached. By varying the half-wave-plate setting, we control the quantum-coin bias thereby observing a transition from quasi-periodic dynamics to ballistic diffusion. © 2014 IOP Publishing Ltd and Deutsche Physikalische Gesellschaft.

Sui Y.,Queen Mary, University of London | Ding H.,Hefei University of Technology | Spelt P.D.M.,École Centrale Lyon | Spelt P.D.M.,University Claude Bernard Lyon 1
Annual Review of Fluid Mechanics | Year: 2014

Computational methods have been extended recently to allow for the presence of moving contact lines in simulated two-phase flows. The predictive capability offered by these methods is potentially large, joining theoretical and experimental methods. Several challenges rather unique to this area need to be overcome, however, notably regarding the conditions near a moving contact line and the very large separation of length scales in these flows. We first summarize the main models for moving contact lines and follow with an overview of computational methods that includes direct continuum approaches and macroscale models that resolve only the large-scale flow by modeling the effects of the conditions near the contact line using theory. Results are presented for contact-line motion on ideal as well as patterned and grooved surfaces and for extensions to account for complexities such as thermocapillarity and phase change. Copyright © 2014 by Annual Reviews. All rights reserved.

Liu B.-H.,Hefei University of Technology | Li L.,Hefei University of Technology | Huang Y.-F.,Hefei University of Technology | Li C.-F.,Hefei University of Technology | And 4 more authors.
Nature Physics | Year: 2011

Realistic quantum mechanical systems are always exposed to an external environment. This often induces Markovian processes in which the system loses information to its surroundings. However, many quantum systems exhibit non-Markovian behaviour with a flow of information from the environment back to the system. The environment usually consists of large number of degrees of freedom which are difficult to control, but some sophisticated schemes for reservoir engineering have been developed. The control of open systems plays a decisive role, for example, in proposals for entanglement generation and dissipative quantum computation, for the design of quantum memories and in quantum metrology. Here we report an all-optical experiment which allows one to drive the open system from the Markovian to the non-Markovian regime, to control the information flow between the system and the environment, and to determine the degree of non-Markovianity by measurements on the open system. © 2011 Macmillan Publishers Limited. All rights reserved.

Jin S.,Hefei University of Technology | Jin S.,University of Wyoming | Fallgren P.H.,Western Research Institute
Journal of Hazardous Materials | Year: 2010

Chlorinated compounds such as trichloroethene (TCE) are recalcitrant contaminants commonly detected in soil and groundwater. Contemporary remedies such as electron donor amendment tend to be less or ineffective in treating chlorinated compounds in matrix of lower permeability, such as clay. In this study, electrically induced reduction (EIR) was tested by inserting electrodes in saturated clay containing 122.49-125.43 mg TCE kg-1. Weak electric potentials (E) of 6, 9, and 12 V m-1 were applied, and up to 97% of TCE were depleted during the study period. Corresponding increases in chloride concentrations was observed during TCE depletion, indicating a reductive dechlorination pathway. No migration of TCE was observed between the two electrodes, neither were intermediate compounds such as dichloroethene (DCE) or vinyl chloride (VC). Results were also tested against a mathematical equation we previously established for field applications. Electrically induced reduction may offer a novel method for in situ degradation of chlorinated contaminants, especially in low-permeable media such as clay. © 2009 Elsevier B.V. All rights reserved.

Xu J.-S.,Hefei University of Technology | Sun K.,Hefei University of Technology | Li C.-F.,Hefei University of Technology | Xu X.-Y.,Hefei University of Technology | And 4 more authors.
Nature Communications | Year: 2013

Revivals of quantum correlations in composite open quantum systems are a useful dynamical feature against detrimental effects of the environment. Their occurrence is attributed to flows of quantum information back and forth from systems to quantum environments. However, revivals also show up in models where the environment is classical, thus unable to store quantum correlations, and forbids system-environment back-action. This phenomenon opens basic issues about its interpretation involving the role of classical environments, memory effects, collective effects and system-environment correlations. Moreover, an experimental realization of back-action-free quantum revivals has applicative relevance as it leads to recover quantum resources without resorting to more demanding structured environments and correction procedures. Here we introduce a simple two-qubit model suitable to address these issues. We then report an all-optical experiment which simulates the model and permits us to recover and control, against decoherence, quantum correlations without back-action. We finally give an interpretation of the phenomenon by establishing the roles of the involved parties. © 2013 Macmillan Publishers Limited. All rights reserved.

Wang G.,Hefei University of Technology | Wang G.,Beihang University
ACS Applied Materials and Interfaces | Year: 2010

Three-phase-percolative composites with ZnO radial nanoclusters (R-ZnO) and BaTiO3 (BT) nanoparticles embedded into polyvinylidene fluoride (PVDF) were prepared by using a simple blending and hot-molding technique. The BT + PVDF composite with a volume fraction of 30 vol % BT particles were employed as a thermoplastic-ceramic matrix. Compared with the two-phase-percolative composites of R-ZnO/PVDF, the three-phase-percolative (R-ZnO/(BT + PVDF)) composites showed enhanced dielectric constant and decreased dielectric loss. The percolation theory was used to explain the experimental results. The increased percolation threshold was studied in detail, and the thermal stability was also investigated. © 2010 American Chemical Society.

Du H.,Nanjing Southeast University | Du H.,Hefei University of Technology | Li S.,Nanjing Southeast University | Ding S.,Jiangsu University
Asian Journal of Control | Year: 2013

In this paper, the consensus problem is investigated via bounded controls for the multi-agent systems with or without communication. Based on the nested saturation method, the saturated control laws are designed to solve the consensus problem. Under the designed saturated control laws, the transient performance of the closed-loop system can be improved by tuning the saturation level. First of all, asymptotical consensus algorithms with bounded control inputs are proposed for the multi-agent systems with or without communication delays. Under these consensus algorithms, the states' consensus can be achieved asymptotically. Then, based on a kind of novel nonlinear saturation functions, bounded finite-time consensus algorithms are further developed. It is shown that the states' consensus can be achieved in finite time. Finally, two examples are given to verify the efficiency of the proposed methods. © 2012 John Wiley and Sons Asia Pte Ltd and Chinese Automatic Control Society.

Gao Q.,Hefei University of Technology | Wang R.,Tongji University | Xu Z.,Hefei University of Technology | Hua Y.,University of California
Journal of Lightwave Technology | Year: 2015

In this paper, we consider the problem of constellation design for a visible light communication (VLC) system using red/green/blue light-emitting diodes (RGB LED), and propose a method termed dc-informative joint color-frequency modulation (DCI-JCFM). This method jointly utilizes available diversity resources including different optical wavelengths, multiple baseband subcarriers, and adaptive dc-bias. Constellation is designed in a high-dimensional space, where the compact sphere packing advantage over lower dimensional counterparts is utilized. Taking into account multiple practical illumination constraints, a non-convex optimization problem is formulated, seeking the least error rate with a fixed spectral efficiency. The proposed scheme is compared with a decoupled scheme, where constellation is designed separately for each LED. Notable gains for DCI-JCFM are observed through simulations, where balanced, unbalanced, and very unbalanced color illuminations are considered. © 1983-2012 IEEE.

Fan Q.,Hefei University of Technology | Wang C.,Hefei University of Technology | Han Y.,Hefei University of Technology | Zhu J.,Hefei University of Technology | And 4 more authors.
Angewandte Chemie - International Edition | Year: 2013

A hexagonal macrocycle consisting of 18 phenylene units (hyperbenzene) was synthesized on a Cu(111) surface in ultrahigh vacuum by Ullmann coupling of six 4,4′′-dibromo-m-terphenyl molecules. The large diameter of 21.3 Å and the ability to assemble in arrays makes hyperbenzene an interesting candidate for a nanotrough that could enclose metallic, semiconducting, or molecular quantum dots. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Jo S.B.,Pohang University of Science and Technology | Lee W.H.,Pohang University of Science and Technology | Qiu L.,Hefei University of Technology | Cho K.,Pohang University of Science and Technology
Journal of Materials Chemistry | Year: 2012

This article reviews the recent advances in organic electronics based on polymer blends with one-dimensional (1D) nanowires (NWs) of π-conjugated polymers. Self-assembled polymer semiconducting NWs are fascinating building blocks for their directional extension of inter- and intramolecular π-conjugation. This extensive conjugation provides unique electrical and optical properties that benefit applications in organic electronic devices. Outstanding performances are particularly expected from blending these NWs with insulating polymers or semiconducting molecules. Several representative reports describing NWs prepared from semiconducting/insulating polymer blends, conjugated block copolymers, or electrospinning for use as high-performance organic thin-film transistors (OTFTs) are discussed. The concepts of phase-separation behavior and the growth of crystalline NWs from multi-phase blend solutions are also illustrated. Research into the solubility-induced formation of NWs from semiconducting polymer/n-type small molecule blends for high-efficiency organic photovoltaic solar cells (OPVs) is introduced. In addition, the effects of the chemical properties of conjugated polymers on the optical and electrical properties of NWs and the use of ordered NW structures in OPVs are summarized. This critical review provides insights and a new perspective on the optimization of blend morphologies, which consequently enhances the performance of organic electronic devices. © 2012 The Royal Society of Chemistry.

Zhai J.,Nanjing Southeast University | Du H.,Nanjing Southeast University | Du H.,Hefei University of Technology
ISA Transactions | Year: 2013

This paper investigates the problem of semi-global stabilization by output feedback for a class of nonlinear systems using homogeneous domination approach. For each subsystem, we first design an output feedback stabilizer for the nominal system without the perturbing nonlinearities. Then, based on the ideas of the homogeneous systems theory and the adding a power integrator technique, a series of homogeneous output feedback stabilizers are constructed recursively for each subsystem and the closed-loop system is rendered semi-globally asymptotically stable. The efficiency of the output feedback stabilizers is demonstrated by a simulation example.

Xu N.,Hefei University of Technology | Frenkel D.,University of Cambridge | Frenkel D.,FOM Institute for Atomic and Molecular Physics | Liu A.J.,University of Pennsylvania
Physical Review Letters | Year: 2011

We propose a free-energy-based Monte Carlo method to measure the volume of potential-energy basins in configuration space. Using this approach we can estimate the number of distinct potential-energy minima, even when this number is much too large to be sampled directly. We validate our approach by comparing our results with the direct enumeration of distinct jammed states in small packings of frictionless spheres. We find that the entropy of distinct packings is extensive and that the entropy of distinct hard-sphere packings must have a maximum as a function of packing fraction. © 2011 American Physical Society.

Yang H.-R.,Sichuan University | Lei J.,Sichuan University | Li L.,Hefei University of Technology | Fu Q.,Sichuan University | Li Z.-M.,Sichuan University
Macromolecules | Year: 2012

It has been well established that the entangled molecular network facilitates the formation of shish-kebabs under flow field, however, the entangled network, usually formed by long chains, tends to disentangle due to molecular relaxation. In the present work, a small amount of lightly cross-linked polyethylene (LCPE), which can be considered as stable molecular chain networks, was added to short-chain polyethylene and then injection-molded using a modified injection molding technology-oscillation shear injection molding (OSIM), which can exert a successive shear field on the melt in the mold cavity during packing stage. The hierarchic structure of the OSIM samples was characterized through differential scanning calorimetry (DSC), wide-angle X-ray diffraction (WAXD) and scanning electron microscopy (SEM). It was found that the oscillation flow field promoted the formation of interlinked shish-kebabs in the intermediate layer of OSIM samples, while there are still typical spherulites in the core layer of OSIM neat polyethylene (PE). The interlinked shish-kebab structure led to remarkable mechanical enhancement from 27.6 and 810.2 MPa of conventional injection molding (CIM) samples to 42.7 and 1091.9 MPa of OSIM samples for tensile strength and modulus, respectively. More importantly, under the same flow condition, the samples containing LCPE networks (termed PEX) exhibit rich shish-kebab structure both in the intermediate and core layers. Moreover, the addition of LCPE also generated stronger interlinked shish-kebabs, in which kebabs and shishes are connected by covalent bonds, rather than topological entanglement points. This special structure leads to further reinforcement from 29.6 and 879.5 MPa of CIM PEX samples to 57.5 and 1311.7 MPa of OSIM PEX samples for tensile strength and modulus, respectively. The results demonstrated that the networks with stable entanglement points are more helpful to induce the formation of shishes under flow than those with topological entanglement points. Our results set up a new method to reinforce polymer parts by tailoring the structure and morphology. © 2012 American Chemical Society.

Qian C.,University of Texas at San Antonio | Du H.,Nanjing Southeast University | Du H.,Hefei University of Technology
IEEE Transactions on Automatic Control | Year: 2012

In the literature, it has been proved that under a lower-triangular linear growth condition, a class of uncertain nonlinear systems can be globally stabilized by a linear state feedback controller (Tsinias) and later by a linear output feedback controller (Qian and Lin), both in the continuous-time form. This technical note shows that the same continuous-time system under the same assumption can be globally stabilized by a sampled-data output feedback controller whose observer and control law are discrete-time and linear, and hence can be easily implemented by computers. © 2012 IEEE.

Wu R.,Beihang University | Huang W.,Hefei University of Technology | Chen D.-R.,Beihang University
IEEE Signal Processing Letters | Year: 2013

Orthogonal matching pursuit (OMP) algorithm is a classical greedy algorithm in Compressed Sensing. In this letter, we study the performance of OMP in recovering the support of a sparse signal from a few noisy linear measurements. We consider two types of bounded noise and our analysis is in the framework of restricted isometry property (RIP). It is shown that under some conditions on RIP and the minimum magnitude of the nonzero elements of the sparse signal, OMP with proper stopping rules can recover the support of the signal exactly from the noisy observation. We also discuss the case of Gaussian noise. Our conditions on RIP improve some existing results. © 1994-2012 IEEE.

Cui J.,Monash University | Cui J.,Hefei University of Technology | Adeloju S.B.,Monash University | Wu Y.,Hefei University of Technology
Analytica Chimica Acta | Year: 2014

A highly sensitive amperometric nanobiosensor has been developed by integration of glucose oxidase (GOx) with a gold nanowires array (AuNWA) by cross-linking with a mixture of glutaraldehyde (GLA) and bovine serum albumin (BSA). An initial investigation of the morphology of the synthesized AuNWA by field emission scanning electron microscopy (FESEM) and field emission transmission electron microscopy (FETEM) revealed that the nanowires array was highly ordered with rough surface, and the electrochemical features of the AuNWA with/without modification were also investigated. The integrated AuNWA-BSA-GLA-GOx nanobiosensor with Nafion membrane gave a very high sensitivity of 298.2μAcm-2mM-1 for amperometric detection of glucose, while also achieving a low detection limit of 0.1μM, and a wide linear range of 5-6000μM. Furthermore, the nanobiosensor exhibited excellent anti-interference ability towards uric acid (UA) and ascorbic acid (AA) with the aid of Nafion membrane, and the results obtained for the analysis of human blood serum indicated that the device is capable of glucose detection in real samples. © 2013 Elsevier B.V.

Ou M.,Nanjing Southeast University | Du H.,Nanjing Southeast University | Du H.,Hefei University of Technology | Li S.,Nanjing Southeast University
International Journal of Robust and Nonlinear Control | Year: 2014

This paper considers finite-time formation control problem for a group of nonholonomic mobile robots. The desired formation trajectory is represented by a virtual dynamic leader whose states are available to only a subset of the followers and the followers have only local interaction. First of all, a continuous distributed finite-time observer is proposed for each follower to estimate the leader's states in a finite time. Then, a continuous distributed cooperative finite-time tracking control law is designed for each mobile robot. Rigorous proof shows that the group of mobile robots converge to the desired geometric formation pattern in finite time. At the same time, all the robots can track the desired formation trajectory in finite time. Simulation example illustrates the effectiveness of our method. Copyright © 2012 John Wiley & Sons, Ltd.

Liu B.-H.,Hefei University of Technology | Li L.,Hefei University of Technology | Huang Y.-F.,Hefei University of Technology | Li C.-F.,Hefei University of Technology | And 4 more authors.
Nature Physics | Year: 2011

Realistic quantum mechanical systems are always exposed to an external environment. This often induces Markovian processes in which the system loses information to its surroundings. However, many quantum systems exhibit non-Markovian behaviour with a flow of information from the environment back to the system. The environment usually consists of large number of degrees of freedom which are difficult to control, but some sophisticated schemes for reservoir engineering have been developed. The control of open systems plays a decisive role, for example, in proposals for entanglement generation and dissipative quantum computation, for the design of quantum memories and in quantum metrology. Here we report an all-optical experiment which allows one to drive the open system from the Markovian to the non-Markovian regime, to control the information flow between the system and the environment, and to determine the degree of non-Markovianity by measurements on the open system.

Zhao N.,Beijing Computational Science Research Center | Zhao N.,Hefei University of Technology | Yin Z.-Q.,Tsinghua University
Physical Review A - Atomic, Molecular, and Optical Physics | Year: 2014

We propose an ultrasensitive mass spectrometer based on a coupled quantum-bit-oscillator system. Under dynamical decoupling control of the quantum bit (qubit), the qubit coherence exhibits a comb structure in the time domain. The time-comb structure enables high-precision measurements of oscillator frequency, which can be used as an ultrasensitive mass spectrometer. We show that, in the ideal case, the sensitivity η of the proposed mass spectrometer has better performance at higher temperature and scales with the temperature T as η∼T-1/2. While taking into account qubit and oscillator decay, the optimal sensitivity reaches a universal value independent of environmental temperature T. The measurement sensitivity η also shows an improved dependence on the control-pulse number N as η∼N-3/2, in comparison with the N-1/2 scaling in previous magnetometry studies. With the present technology on solid-state spin qubit and high-quality optomechanical system, our proposal is feasible to realize an ultrasensitive room-temperature mass spectrometer. © 2014 American Physical Society.

Laine E.-M.,University of Turku | Breuer H.-P.,Albert Ludwigs University of Freiburg | Piilo J.,University of Turku | Li C.-F.,Hefei University of Technology | Guo G.-C.,Hefei University of Technology
Physical Review Letters | Year: 2012

We explore the possibility to generate nonlocal dynamical maps of an open quantum system through local system-environment interactions. Employing a generic decoherence process induced by a local interaction Hamiltonian, we show that initial correlations in a composite environment can lead to nonlocal open system dynamics which exhibit strong memory effects, although the local dynamics is Markovian. In a model of two entangled photons interacting with two dephasing environments, we find a direct connection between the degree of memory effects and the amount of correlation in the initial environmental state. The results demonstrate that, contrary to conventional wisdom, enlarging an open system can change the dynamics from Markovian to non-Markovian. © 2012 American Physical Society.

Niu P.,CAS Shenyang Institute of Metal Research | Yin L.-C.,CAS Shenyang Institute of Metal Research | Yang Y.-Q.,CAS Shenyang Institute of Metal Research | Yang Y.-Q.,Hefei University of Technology | And 3 more authors.
Advanced Materials | Year: 2014

There is an inherent driving force to narrow the bandgap of photocatalysts towards this value. Introducing heteroatoms as a general strategy of tuning the bandgap of semiconductors has been attempted to narrow the bandgap of melon in order to extend its light absorption range. Compared to the intensive studies on oxygen vacancies, the underlying role of nitrogen vacancies in modulating optical and photocatalytic properties is rarely considered in developing nitride-based photocatalysts. On the other hand, the spatial distribution of dopants is recognized as an essential issue in modifying the electronic structure of photocatalysts. Homogeneous doping of appropriate heteroatoms throughout a whole particle is indispensable for effective bandgap narrowing, while surface doping can only result in some localized states in the bandgap.

Xu J.-S.,Hefei University of Technology | Yung M.-H.,Tsinghua University | Yung M.-H.,Harvard University | Xu X.-Y.,Hefei University of Technology | And 5 more authors.
Nature Photonics | Year: 2014

Simulation of the low-temperature properties of many-body systems remains one of the major challenges in theoretical and experimental quantum information science. We present, and demonstrate experimentally, a universal (pseudo) cooling method that is applicable to any physical system that can be simulated by a quantum computer. This method allows us to distil and eliminate hot components of quantum states like a quantum Maxwell's demon. The experimental implementation is realized with a quantum optical network, and the results are in full agreement with theoretical predictions (with fidelity higher than 0.978). Applications of the proposed pseudo-cooling method include simulations of the low-temperature properties of physical and chemical systems that are intractable with classical methods. © 2014 Macmillan Publishers Limited.

Liu Q.,Hefei University of Technology | Chen E.,Hefei University of Technology | Xiong H.,Rutgers University | Ding C.H.Q.,University of Texas at Arlington | Chen J.,Tsinghua University
IEEE Transactions on Systems, Man, and Cybernetics, Part B: Cybernetics | Year: 2012

Recommender systems suggest a few items from many possible choices to the users by understanding their past behaviors. In these systems, the user behaviors are influenced by the hidden interests of the users. Learning to leverage the information about user interests is often critical for making better recommendations. However, existing collaborative-filtering-based recommender systems are usually focused on exploiting the information about the user's interaction with the systems; the information about latent user interests is largely underexplored. To that end, inspired by the topic models, in this paper, we propose a novel collaborative-filtering-based recommender system by user interest expansion via personalized ranking, named iExpand. The goal is to build an item-oriented model-based collaborative-filtering framework. The iExpand method introduces a three-layer, user-interests-item, representation scheme, which leads to more accurate ranking recommendation results with less computation cost and helps the understanding of the interactions among users, items, and user interests. Moreover, iExpand strategically deals with many issues that exist in traditional collaborative-filtering approaches, such as the overspecialization problem and the cold-start problem. Finally, we evaluate iExpand on three benchmark data sets, and experimental results show that iExpand can lead to better ranking performance than state-of-The-art methods with a significant margin. © 2011 IEEE.

Zhang W.,Hefei University of Technology | Liang W.,Hefei University of Technology | Zhao Y.,Xiamen University
Journal of Chemical Physics | Year: 2010

Combining first-principles calculations and non-Condon charge transfer rates proposed by us recently [Y. Zhao and W. Z. Liang, J. Chem. Phys. 130, 034111 (2009)], we investigated non-Condon effect on charge carrier mobility of organic semiconductor dithiophene-tetrathiafulvalene (DT-TTF) crystal. The first-principles results reveal that only several high-frequency intramolecular vibrational modes dominate the reorganization energy, and the nuclear-coordinate dependence of electronic coupling prefers to perform an exponential or Gaussian property for most intermolecular modes rather than a linear one as assumed in conventional models. Furthermore, the electronic coupling of an isolated DT-TTF dimer is indeed affected by the surrounding molecules. The predicted non-Condon mobilities with use of the obtained structure parameters are always greater than those from Condon approximation, and the non-Condon dynamic disorder is not important for DT-TTF, which is also confirmed by molecular dynamics simulation. More interestingly, the bandlike property can be predicted under the hopping mechanism when the nuclear tunneling is incorporated. © 2010 American Institute of Physics.

Guo X.,Fudan University | Wang L.,Fudan University | Li J.,Fudan University | Ding Z.,Chinese Academy of Sciences | And 13 more authors.
Nature | Year: 2015

DNA methylation is an important epigenetic modification that is essential for various developmental processes through regulating gene expression, genomic imprinting, and epigenetic inheritance. Mammalian genomic DNA methylation is established during embryogenesis by de novo DNA methyltransferases, DNMT3A and DNMT3B, and the methylation patterns vary with developmental stages and cell types. DNA methyltransferase 3-like protein (DNMT3L) is a catalytically inactive paralogue of DNMT3 enzymes, which stimulates the enzymatic activity of Dnmt3a. Recent studies have established a connection between DNA methylation and histone modifications, and revealed a histone-guided mechanism for the establishment of DNA methylation. The ATRX-DNMT3-DNMT3L (ADD) domain of Dnmt3a recognizes unmethylated histone H3 (H3K4me0). The histone H3 tail stimulates the enzymatic activity of Dnmt3a in vitro, whereas the molecular mechanism remains elusive. Here we show that DNMT3A exists in an autoinhibitory form and that the histone H3 tail stimulates its activity in a DNMT3L-independent manner. We determine the crystal structures of DNMT3A-DNMT3L (autoinhibitory form) and DNMT3A-DNMT3L-H3 (active form) complexes at 3.82 and 2.90 Å resolution, respectively. Structural and biochemical analyses indicate that the ADD domain of DNMT3A interacts with and inhibits enzymatic activity of the catalytic domain (CD) through blocking its DNA-binding affinity. Histone H3 (but not H3K4me3) disrupts ADD-CD interaction, induces a large movement of the ADD domain, and thus releases the autoinhibition of DNMT3A. The finding adds another layer of regulation of DNA methylation to ensure that the enzyme is mainly activated at proper targeting loci when unmethylated H3K4 is present, and strongly supports a negative correlation between H3K4me3 and DNA methylation across the mammalian genome. Our study provides a new insight into an unexpected autoinhibition and histone H3-induced activation of the de novo DNA methyltransferase after its initial genomic positioning. © 2015 Macmillan Publishers Limited. All rights reserved.

Zhao Y.,Xiamen University | Liang W.,Hefei University of Technology
Chemical Society Reviews | Year: 2012

This tutorial review primarily illustrates rate theories for charge transfer and separation in organic molecules for solar cells. Starting from the Fermi's golden rule for weak electronic coupling, we display the microcanonical and canonical rates, as well as the relationship with the Marcus formula. The fluctuation effect of bridges on the rate is further emphasized. Then, several rate approaches beyond the perturbation limit are revealed. Finally, we discuss the electronic structure theory for calculations of the electronic coupling and reorganization energy that are two key parameters in charge transfer, and show several applications. © 2012 The Royal Society of Chemistry.

Wang Z.,Stanford University | Wang Z.,Hefei University of Technology | Wang Z.,Tsinghua University | Qi X.-L.,Stanford University | Zhang S.-C.,Stanford University
Physical Review B - Condensed Matter and Materials Physics | Year: 2011

We investigate the three-dimensional, time-reversal invariant topological superconductors with generic interaction by their response to external fields. The first description is a gravitational topological field theory, which gives a Z2 classification of topological superconductors, and predicts a half quantized thermal Hall effect on the surface. The second description introduces an s-wave proximity pairing field on the surface, and the associated topological defects give an integer Z classification of the topological superconductors. © 2011 American Physical Society.

Wang X.,Hefei University of Technology | Zhou Y.,Hefei University of Technology | Liu Z.,University of California at Los Angeles
Journal of Vision | Year: 2013

One hypothesis in visual perceptual learning is that the amount of transfer depends on the difficulty of the training and transfer tasks (Ahissar & Hochstein, 1997; Liu, 1995, 1999). Jeter, Dosher, Petrov, and Lu (2009), using an orientation discrimination task, challenged this hypothesis by arguing that the amount of transfer depends only on the transfer task but not on the training task. Here we show in a motion direction discrimination task that the amount of transfer indeed depends on the difficulty of the training task. Specifically, participants were first trained with either 4° or 8° direction discrimination along one average direction. Their transfer performance was then tested along an average direction 908 away from the trained direction. A variety of transfer measures consistently demonstrated that transfer performance depended on whether the participants were trained on 4° or 8° directional difference. The results contradicted the prediction that transfer was independent of the training task difficulty. © 2013 ARVO.

Yu J.,Xiamen University | Wang M.,Hefei University of Technology | Tao D.,Intelligent Systems Technology, Inc.
IEEE Transactions on Image Processing | Year: 2012

In image processing, cartoon character classification, retrieval, and synthesis are critical, so that cartoonists can effectively and efficiently make cartoons by reusing existing cartoon data. To successfully achieve these tasks, it is essential to extract visual features that comprehensively represent cartoon characters and to construct an accurate distance metric to precisely measure the dissimilarities between cartoon characters. In this paper, we introduce three visual features, color histogram, shape context, and skeleton, to characterize the color, shape, and action, respectively, of a cartoon character. These three features are complementary to each other, and each feature set is regarded as a single view. However, it is improper to concatenate these three features into a long vector, because they have different physical properties, and simply concatenating them into a high-dimensional feature vector will suffer from the so-called curse of dimensionality. Hence, we propose a semisupervised multiview distance metric learning (SSM-DML). SSM-DML learns the multiview distance metrics from multiple feature sets and from the labels of unlabeled cartoon characters simultaneously, under the umbrella of graph-based semisupervised learning. SSM-DML discovers complementary characteristics of different feature sets through an alternating optimization-based iterative algorithm. Therefore, SSM-DML can simultaneously accomplish cartoon character classification and dissimilarity measurement. On the basis of SSM-DML, we develop a novel system that composes the modules of multiview cartoon character classification, multiview graph-based cartoon synthesis, and multiview retrieval-based cartoon synthesis. Experimental evaluations based on the three modules suggest the effectiveness of SSM-DML in cartoon applications. © 2012 IEEE.

Zhou T.,University of Technology, Sydney | Tao D.,University of Technology, Sydney | Wu X.,Hefei University of Technology
Machine Learning | Year: 2012

Directly applying single-label classification methods to the multi-label learning problems substantially limits both the performance and speed due to the imbalance, dependence and high dimensionality of the given label matrix. Existing methods either ignore these three problems or reduce one with the price of aggravating another. In this paper, we propose a {0, 1} label matrix compression and recovery method termed "compressed labeling (CL)" to simultaneously solve or at least reduce these three problems. CL first compresses the original label matrix to improve balance and independence by preserving the signs of its Gaussian random projections. Afterward, we directly utilize popular binary classification methods (e.g., support vector machines) for each new label. A fast recovery algorithm is developed to recover the original labels from the predicted new labels. In the recovery algorithm, a "labelset distilling method" is designed to extract distilled labelsets (DLs), i.e., the frequently appeared label subsets from the original labels via recursive clustering and subtraction. Given a distilled and an original label vector, we discover that the signs of their random projections have an explicit joint distribution that can be quickly computed from a geometric inference. Based on this observation, the original label vector is exactly determined after performing a series of Kullback-Leibler divergence based hypothesis tests on the distribution about the new labels. CL significantly improves the balanceof the training samples and reduces the dependence between different labels. Moreover, it accelerates the learning process by training fewer binary classifiers for compressed labels, and makes use of label dependence via DLs based tests. Theoretically, we prove the recovery bounds of CL which verifies the effectiveness of CL for label compression and multi-label classification performance improvement brought by label correlations preserved in DLs.We show the effectiveness, efficiency and robustness of CL via 5 groups of experiments on 21 datasets from text classification, image annotation, scene classification, music categorization, genomics and web page classification. © The Author(s) 2012.

Zhang Y.,Sun Yat Sen University | Lu Y.-X.,Sun Yat Sen University | Liu J.,Hefei University of Technology | Yang C.,Sun Yat Sen University | And 2 more authors.
PLoS Genetics | Year: 2013

Insect fat body is the organ for intermediary metabolism, comparable to vertebrate liver and adipose tissue. Larval fat body is disintegrated to individual fat body cells and then adult fat body is remodeled at the pupal stage. However, little is known about the dissociation mechanism. We find that the moth Helicoverpa armigera cathepsin L (Har-CL) is expressed heavily in the fat body and is released from fat body cells into the extracellular matrix. The inhibitor and RNAi experiments demonstrate that Har-CL functions in the fat body dissociation in H. armigera. Further, a nuclear protein is identified to be transcription factor Har-Relish, which was found in insect immune response and specifically binds to the promoter of Har-CL gene to regulate its activity. Har-Relish also responds to the steroid hormone ecdysone. Thus, the dissociation of the larval fat body is involved in the hormone (ecdysone)-transcription factor (Relish)-target gene (cathepsin L) regulatory pathway. © 2013 Zhang et al.

Zheng J.-S.,Tsinghua University | Zheng J.-S.,Hefei University of Technology | Chang H.-N.,Tsinghua University | Wang F.-L.,Hefei University of Technology | And 2 more authors.
Journal of the American Chemical Society | Year: 2011

An operationally simple method for the synthesis of peptide thioesters is developed using standard Fmoc solid-phase peptide synthesis procedures. The method relies on the use of a premade enamide-containing amino acid which, in the final TFA cleavage step, renders the desired thioester functionality through an irreversible intramolecular N-to-S acyl transfer. © 2011 American Chemical Society.

Xu J.,Hefei University of Technology | Xiao B.,Tsinghua University | Xiao B.,CAS Lanzhou Institute of Chemical Physics | Xie C.-Q.,Hefei University of Technology | And 4 more authors.
Angewandte Chemie - International Edition | Year: 2012

New couple: The Cu-promoted trifluoromethylation of primary and secondary alkylboronic acids with TMSCF3 extends the scope of transition-metal-catalyzed trifluoromethylation reactions to sp 3-hybridized carbon centers. It also represents one of the first examples for Cu-catalyzed C-C cross-coupling reactions of alkylboronic acid derivatives. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Ju M.-G.,Hefei University of Technology | Liang W.,Xiamen University
Journal of Physical Chemistry C | Year: 2013

A step-by-step theoretical protocol based on the density functional theory (DFT) and time-dependent DFT (TD-DFT) at both the molecular and periodic levels have been performed to study a zinc porphyrin complex (named YDoc) sensitized TiO2 solar cell including dye excitations, electron injection, the regeneration of photooxidized dyes and the effect of electrolyte additives. Our study reveals the possibility of a favorable electron transfer from the excited dye to the semiconductor conduction band (CB) and suggests three possible pathways of the electron injection from the dye to the nanoparticle (TiO 2)38. One is the direct one-step injection by photoexcitation, and the other two are from the different parts of the excited dye to the nanoparticle. The influence of the electrolyte composition on the geometric and electronic features of the dye/TiO2 system has also been studied. It is found that, with the additive of the lithium ion, the energy gap between the LUMO of dye and the TiO2 CB edge increases, which subsequently increases the driving force for the ultrafast excited-state electron injection, contrary to the effect of 4-tert-butylpyridine additive. The computational results of the oxidized dye interacting with I- and I2- reveal that there are a few possible mechanisms for the regeneration of oxidized dye. The effective mechanisms of the regeneration are suggested. © 2013 American Chemical Society.

Feng H.,Hefei University of Technology | Feng H.,Tsinghua University | Huang J.,Tsinghua University | Li J.,Tsinghua University
Chemical Communications | Year: 2013

A mechanical activated SnO2 nanowire was used as a prominent analytical platform for organic small molecules. The sensing is based on a mechanical response that is triggered by an analyte binding event on the surface of the nanowire. © The Royal Society of Chemistry 2013.

Xiao B.,Hefei University of Technology | Xiao B.,Tsinghua University | Xiao B.,CAS Lanzhou Institute of Chemical Physics | Liu Z.-J.,Hefei University of Technology | And 3 more authors.
Journal of the American Chemical Society | Year: 2013

An unexpected C-H activation/C-C cross-coupling reaction has been found to occur between pyridine N-oxides and general nonactivated secondary and even tertiary alkyl bromides. It provides a practically useful approach for the synthesis of alkylated pyridine derivatives. Experimental observations indicated that the C-Br cleavage step involves a radical-type process. Thus, the title reaction provides a rather extraordinary example of Pd-catalyzed cross-coupling of secondary and tertiary aliphatic electrophiles. © 2013 American Chemical Society.

Sharma S.,Hefei University of Technology | Sharma S.,DAV University
Nonlinear Dynamics | Year: 2015

In this paper, a new lattice hydrodynamic traffic flow model is proposed by considering the driver’s anticipation effect (DAE) in sensing optimal current difference (OCD) for two-lane system. The effect of anticipation parameter on the stability of traffic flow is examined through linear stability analysis and shown that it can significantly enlarge the stability region on the phase diagram. Nonlinear analysis is conducted, and mKdV equation is derived to describe propagation behavior of a density wave near the critical point. The driver’s physical delay in sensing optimal current difference effect is also investigated and found that it has different effect on two-lane traffic based on whether lane changing is allowed or not. Simulation results are found in good agreement with the theoretical findings, which confirms that traffic jam can be suppressed efficiently by considering the DAEOCD effect in a two-lane traffic system. © Springer Science+Business Media Dordrecht 2015.

Eckenhoff W.T.,University of Rochester | McNamara W.R.,College of William and Mary | Du P.,Hefei University of Technology | Eisenberg R.,University of Rochester
Biochimica et Biophysica Acta - Bioenergetics | Year: 2013

The generation of H2 from protons and electrons by complexes of cobalt has an extensive history. During the past decade, interest in this subject has increased as a result of developments in hydrogen generation that are driven electrochemically or photochemically. This article reviews the subject of hydrogen generation using Co complexes as catalysts and discusses the mechanistic implications of the systems studied for making H2. This article is part of a Special Issue entitled: Metals in Bioenergetics and Biomimetics Systems. © 2013 Elsevier B.V. All rights reserved.

Zhao Z.-F.,Hefei University of Technology | Zheng Y.-F.,Hefei University of Technology | Wei C.-S.,Hefei University of Technology | Wu F.-Y.,CAS Institute of Geology and Geophysics
Lithos | Year: 2011

Zircon Hf and whole-rock Sr-Nd isotopic compositions were determined for postcollisional mafic-ultramafic and felsic intrusive rocks in the Dabie orogen. The results provide not only insights into the character of their source rocks and the nature of crust-mantle interaction, but also constraints on the crustal architecture of continental collision orogen. SHRIMP zircon U-Pb dating gave concordant ages of 121±6 to 131±2Ma for the bimodal intrusives. Zircon Hf isotope analyses gave negative εHf(t) values of -26.3±0.6 to -7.0±0.5 for the mafic-ultramafic rocks, with two-stage Hf model ages of 1.62 to 2.83Ga. Zircons from felsic granitoids also gave negative εHf(t) values of -31.6±0.5 to -16.9±0.9 with two-stage Hf model ages of 2.25 to 3.16Ga. Both the mafic-ultramafic and felsic rocks have high initial 87Sr/86Sr raios of 0.7065 to 0.7084 and very low εNd(t) values of -21.7 to -11.7 for whole-rock. The crust-like geochemical signatures in the mafic-ultramafic rocks suggest their derivation from partial melting of an orogenic lithospheric mantle source that is enriched in radiogenic isotopes as well as incompatible trace elements such as LILE and LREE. It would be generated by reaction of the overlying subcontinental lithospheric mantle (SCLM) wedge peridotite with the felsic melt derived from the subducted continental crust during the continental collision. Therefore, these postcollisional mafic-ultramafic rocks record recycling of the subducted continental crust and consequent crust-mantle interaction in the continental subduction zone. The granitoids have Hf model ages as old as Paleoarchean, which cannot be derived from partial melting of surrounding orthogneisses alone, but requires involvement of more ancient Archean crust in their source region. Thus, their source represents a mixture of crustal rocks from Paleoproterozoic and Paleoarchean basement. In combination of the present and previous studies, the Dabie orogen is suggested to have a three-layer crustal structure prior to the postcollisional magmatism: Central Dabie in the upper with dominantly young Hf model ages of late Mesoproterozoic to Neoproterozoic, North Dabie in the middle with dominantly middle Paleoproterozoic Hf model ages, and the source region of the postcollisional granitoids in the lower with Paleoproterozoic to Paleoarchean Hf model ages. © 2011 Elsevier B.V.

Li W.-C.,Hefei University of Technology | Chen R.-X.,Hefei University of Technology | Zheng Y.-F.,Hefei University of Technology | Li Q.,CAS Institute of Geology and Geophysics | Hu Z.,Wuhan University
Lithos | Year: 2013

Zircon can grow from aqueous fluid and hydrous melt in crustal rocks when they undergo metamorphic dehydration and partial melting under high-pressure (HP) to ultrahigh-pressure (UHP) conditions. A distinction between fluid and melt has important bearing on the development of crustal anatexis in collisional orogens. A genetic transition between fluid and melt is recorded by zircons from pegmatite vein and host UHP gneiss in the Sulu orogen. This transition is elucidated by an integrated study of SIMS U-Pb and O isotope analyses with LA-ICPMS U-Pb isotope and trace element analyses in the zircons. Pegmatite veins yield zircon U-Pb ages of 147-153Ma for new growths, and 700-800Ma for relict cores. A one meter-width pegmatite vein exhibits two episodes of zircon growth at 153±3Ma for inner domain and at 147±2Ma for outer domain. The two types of domains have a series of differences in CL image, inclusion type, REE content and pattern, trace element contents and ratios, and Ti-in-zircon temperature. The inner domain grew from the hydrous melt at 730-840°C, whereas the outer domain grew from the aqueous fluid at 520-650°C. Nevertheless, they have similarly low δ18O values of 1.0-2.3%;, suggesting their growth from O isotope homogeneous media despite the transition from melt to fluid. The host gneiss of this pegmatite vein exhibits three generations of zircon growth, with 180-205Ma at 700-770°C during amphibolite-facies metamorphism, 157±3Ma at 610-670°C for fluid-assisted growth, and 147±2Ma at 780-860°C for melt-assisted growth. The last two types of growth record the development of crustal anatexis from hydration melting to dehydration melting. The other decimeter-width pegmatite vein exhibits only one episode of zircon growth from melt at 149±2Ma and 660-860°C. Its host gneiss exhibits a residual melt texture but no significant growth of zircon, indicating low degree of dehydration melting. Therefore, the zircon domains in the host gneisses record their growth during a transition from aqueous fluid to hydrous melt along a temperature-increasing path, whereas the zircon domains in the pegmatite veins record their growth during a transition from hydrous melt to aqueous fluid along a temperature-decreasing path. Despite the difference in the direction of fluid/melt evolution, the all zircon domains in these gneisses and pegmatite veins record the same event of crustal anatexis in the UHP gneisses. The present study also provides insights into a genetic definition of anatectic melt and thus anatectic zircon. © 2012 Elsevier B.V.

Shi X.,Hefei University of Technology | Goldman R.,Rice University
Computer Aided Geometric Design | Year: 2012

We provide a new technique for implicitizing rational surfaces of revolution using μ-bases. A degree n rational plane curve rotating around an axis generates a degree 2n rational surface. From a μ-basis p,q of this directrix curve, where μ=deg(p)≤deg(q)=n-μ, and a rational parametrization of the circle r(s)=(2s,1-s2,1+s2), we can easily generate three moving planes p*,q*,r* with generic bidegrees (1,μ),(1,n-μ),(2,0) that form a μ-basis for the corresponding surface of revolution. We show that this μ-basis is a powerful bridge connecting the parametric representation and the implicit representation of the surface of revolution. To implicitize the surface, we construct a 3n×3n Sylvester style sparse resultant matrix Rs,t for the three bidegree polynomials p*,q*,r*. Applying Gaussian elimination, we derive a 2n×2n sparse matrix Ss,t, and we prove that det(Ss,t)=0 is the implicit equation of the surface of revolution. Using Bezoutians, we also construct a 2(n-μ)×2(n-μ) matrix Bs,t, and we show that det(Bs,t)=0 is also the implicit equation of the surface of revolution. Examples are presented to illustrate our methods. © 2012 Elsevier B.V. All rights reserved.

Liu H.,Hefei University of Technology | Liu H.,Queensland University of Technology | Chen T.,Hefei University of Technology | Frost R.L.,Queensland University of Technology
Chemosphere | Year: 2014

Goethite, one of the most thermodynamically stable iron oxides, has been extensively researched especially the structure (including surface structure), the adsorption capacity to anions, organic/organic acid (especially for the soil organic carbon) and cations in the natural environment and its potential application in environmental protection. For example, the adsorption of heavy metals by goethite can decrease the concentration of heavy metals in aqueous solution and immobilize; the adsorption to soil organic carbon can decrease the release of carbon and fix carbon. In this present overview, the possible physicochemical properties of the goethite surface contributing to the strong affinity of goethite to nutrients and contaminants in natural environment are reported. Moreover, these chemicals adsorbed by goethite were also summarized and the suggested adsorption mechanism for these adsorbates was elucidated, which will help us understand the role of goethite in natural environment and provide some information about goethite as an absorbent. In addition, the feasibility of goethite used as catalyst carrier and the precursor of NZVI was proposed for removal of environmental pollution. © 2013 Elsevier Ltd.

Watanabe N.,Tohoku University | Chen X.,Hefei University of Technology | Takahashi M.,Tohoku University
Physical Review Letters | Year: 2012

Interference effects on electron momentum profiles have been studied using binary (e, 2e) spectroscopy for the three outermost molecular orbitals of CF 4, which are composed of the F 2p nonbonding atomic orbitals. An analysis of the measured spherically averaged electron momentum densities has clearly shown the presence of oscillatory structures having direct information about the internuclear distance between the F atoms. Furthermore, it is demonstrated that the phase of the oscillatory structures depends upon the orientation in space of the constituent atomic orbitals. © 2012 American Physical Society.

Jia Y.,CAS National Center for Nanoscience and Technology | Jia Y.,Hefei University of Technology | Peng K.,CAS National Center for Nanoscience and Technology | Gong X.-L.,Hefei University of Technology | And 2 more authors.
International Journal of Plasticity | Year: 2011

The creep and recovery of polypropylene/multi-walled carbon nanotube composites were studied. It was found for thermoplastics in general that the creep strain reduces with decreased temperature, and with enhanced content of carbon nanotubes. The incorporation of nanotubes improved the recovery property remarkably, especially at high temperature. The unrecovered creep strain of nanocomposites with content of 1 and 2.8 vol.% carbon nanotubes decreased by 53% and 73% compared to that of polymer matrix. To understand the mechanisms, the Burger's model and Weibull distribution function were employed since the variations in the simulating parameters illustrated the influence of nano-fillers on the creep and recovery performance of the bulk matrix. To further study the recovery properties, the particular contribution of each Burger's element to the total deformation was obtained and the recovery percentage was calculated. The time-temperature-superposition-principle was applied to predict the long-term creep behavior. © 2011 Elsevier Ltd. All rights reserved.

Yi J.,Tsinghua University | Yi J.,CAS Lanzhou Institute of Chemical Physics | Lu X.,Hefei University of Technology | Sun Y.-Y.,Hefei University of Technology | And 4 more authors.
Angewandte Chemie - International Edition | Year: 2013

A nicked reaction: The title reaction of terminal alkynes with non-activated secondary alkyl iodides and bromides was accomplished for the first time. This reaction provides a new and practical approach for the synthesis of substituted alkynes (see scheme; cod=cyclo-1,5-octadiene). Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Zhu L.,Massachusetts Institute of Technology | Chen Y.,Hefei University of Technology | Yuille A.,University of California at Los Angeles
IEEE Transactions on Pattern Analysis and Machine Intelligence | Year: 2010

In this paper, we address the tasks of detecting, segmenting, parsing, and matching deformable objects. We use a novel probabilistic object model that we call a hierarchical deformable template (HDT). The HDT represents the object by state variables defined over a hierarchy (with typically five levels). The hierarchy is built recursively by composing elementary structures to form more complex structures. A probability distributiona parameterized exponential modelis defined over the hierarchy to quantify the variability in shape and appearance of the object at multiple scales. To perform inferenceto estimate the most probable states of the hierarchy for an input imagewe use a bottom-up algorithm called compositional inference. This algorithm is an approximate version of dynamic programming where approximations are made (e.g., pruning) to ensure that the algorithm is fast while maintaining high performance. We adapt the structure-perceptron algorithm to estimate the parameters of the HDT in a discriminative manner (simultaneously estimating the appearance and shape parameters). More precisely, we specify an exponential distribution for the HDT using a dictionary of potentials, which capture the appearance and shape cues. This dictionary can be large and so does not require handcrafting the potentials. Instead, structure-perceptron assigns weights to the potentials so that less important potentials receive small weights (this is like a soft form of feature selection). Finally, we provide experimental evaluation of HDTs on different visual tasks, including detection, segmentation, matching (alignment), and parsing. We show that HDTs achieve state-of-the-art performance for these different tasks when evaluated on data sets with groundtruth (and when compared to alternative algorithms, which are typically specialized to each task). © 2010 IEEE.

Yu J.,Xiamen University | Tao D.,Intelligent Systems Technology, Inc. | Wang M.,Hefei University of Technology
IEEE Transactions on Image Processing | Year: 2012

Recent years have witnessed a surge of interest in graph-based transductive image classification. Existing simple graph-based transductive learning methods only model the pairwise relationship of images, however, and they are sensitive to the radius parameter used in similarity calculation. Hypergraph learning has been investigated to solve both difficulties. It models the high-order relationship of samples by using a hyperedge to link multiple samples. Nevertheless, the existing hypergraph learning methods face two problems, i.e., how to generate hyperedges and how to handle a large set of hyperedges. This paper proposes an adaptive hypergraph learning method for transductive image classification. In our method, we generate hyperedges by linking images and their nearest neighbors. By varying the size of the neighborhood, we are able to generate a set of hyperedges for each image and its visual neighbors. Our method simultaneously learns the labels of unlabeled images and the weights of hyperedges. In this way, we can automatically modulate the effects of different hyperedges. Thorough empirical studies show the effectiveness of our approach when compared with representative baselines. © 2012 IEEE.

Li Y.-M.,Tsinghua University | Li Y.-M.,Hefei University of Technology | Li Y.-T.,Tsinghua University | Pan M.,Tsinghua University | And 4 more authors.
Angewandte Chemie - International Edition | Year: 2014

Sortase-mediated hydrazinolysis of proteins with hydrazine or its derivatives was developed for the production of recombinant protein hydrazides. This process provides an alternative approach for protein semisynthesis through the use of recombinant protein hydrazides as thioester surrogates. It also provides an alternative method for C-terminal modification of proteins with functional units as well as for the preparation of C-to-C fusion proteins. Copyright © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Liu S.-H.,Hohai University | Gao J.-J.,Hohai University | Wang Y.-Q.,Hefei University of Technology | Weng L.-P.,Hohai University
Geotextiles and Geomembranes | Year: 2014

The effectiveness of soilbags in reducing mechanical vibration is investigated, and the influential factors are examined through a series of laboratory tests, including cyclic lateral shear tests, vertical excitation tests and small shaking table tests as well as a soilbag-filled trench field test. The test results illustrate that soilbags have a relatively high damping ratio and variable horizontal stiffness, which are greatly influenced by the materials inside the bags at low vertical stress but become nearly independent of the materials inside the bags at high vertical stress. We find that vertical and horizontal vibrations can be effectively reduced through the use of soilbags. © 2014 Elsevier Ltd.

Gong T.-J.,Hefei University of Technology | Xiao B.,Hefei University of Technology | Cheng W.-M.,Hefei University of Technology | Su W.,Hefei University of Technology | And 5 more authors.
Journal of the American Chemical Society | Year: 2013

A Rh-catalyzed directed C-H cyanation reaction was developed for the first time as a practical method for the synthesis of aromatic nitriles. N-Cyano-N-phenyl-p-toluenesulfonamide, a user-friendly cyanation reagent, was used in the transformation. Many different directing groups can be used in this C-H cyanation process, and the reaction tolerates a variety of synthetically important functional groups. © 2013 American Chemical Society.

Dai J.-J.,Hefei University of Technology | Fang C.,Hefei University of Technology | Xiao B.,Tsinghua University | Xiao B.,CAS Lanzhou Institute of Chemical Physics | And 7 more authors.
Journal of the American Chemical Society | Year: 2013

A copper-promoted trifluoromethylation reaction of aromatic amines is described. This transformation proceeds smoothly under mild conditions and exhibits good tolerance of many synthetically relevant functional groups. It provides an alternative approach for the synthesis of trifluoromethylated arenes and heteroarenes. It also constitutes a new example of the Sandmeyer reaction. © 2013 American Chemical Society.

Cai P.,Tsinghua University | Zhou X.,Tsinghua University | Ruan W.,Tsinghua University | Wang A.,Hefei University of Technology | And 3 more authors.
Nature Communications | Year: 2013

Although the origin of high temperature superconductivity in the iron pnictides is still under debate, it is widely believed that magnetic interactions or fluctuations have a crucial role in triggering Cooper pairing. A key issue regarding the iron pnictide phase diagram is whether long-range magnetic order can coexist with superconductivity microscopically. Here we use scanning tunnelling microscopy to investigate the local electronic structure of underdoped NaFe 1-x Co x As near the spin density wave and superconducting phase boundary. Spatially resolved spectroscopy directly reveals both the spin density wave and superconducting gaps at the same atomic location, providing compelling evidence for the microscopic coexistence of the two phases. The strengths of the two orders are shown to anti-correlate with each other, indicating the competition between them. This work implies that Cooper pairing in the iron pnictides can occur when portions of the Fermi surface are already gapped by the spin density wave order. © 2013 Macmillan Publishers Limited. All rights reserved.

Tang X.,Tsinghua University | Wang Z.,Tsinghua University | Xu Z.,Hefei University of Technology | Ghassemlooy Z.,Northumbria University
Journal of Lightwave Technology | Year: 2014

This paper proposes and analyzes the performance of the multihop free-space optical (FSO) communication links using a heterodyne differential phase-shift keying modulation scheme operating over a turbulence induced fading channel. A novel statistical fading channel model for multihop FSO systems using channel-state-information-assisted and fixed-gain relays is developed incorporating the atmospheric turbulence, pointing errors, and path-loss effects. The closed-form expressions for the moment generating function, probability density function, and cumulative distribution function of the multihop FSO channel are derived using Meijer's G-function. They are then used to derive the fundamental limits of the outage probability and average symbol error rate. Results confirm the performance loss as a function of the number of hops. Effects of the turbulence strength varying from weak-to-moderate and moderate-to-strong turbulence, geometric loss, and pointing errors are studied. The pointing errors can be mitigated by widening the beam at the expense of the received power level, whereas narrowing the beam can reduce the geometric loss at the cost of increased misalignment effects. © 1983-2012 IEEE.

Lin Y.,Hefei University of Technology | Lin Y.,CAS Shenyang Institute of Metal Research | Su D.,CAS Shenyang Institute of Metal Research | Su D.,Fritz Haber Institute of the Max Planck Society
ACS Nano | Year: 2014

Annealed ultradispersed nanodiamond (ADD) with sp2 curved concentric graphitic shells is an interesting hybrid material consisting of the remarkable surface properties of graphene-based nanomaterials and the intrinsic properties of a diamond core. In this case, based on its specific properties and surface oxygen functional groups, nitrogen-modified ADD powders have been tunably synthesized via three different preparation methods in a calcination treatment process. The detailed formation and dynamic behaviors of the nitrogen species on the modified ADD during the preparation process are revealed by elemental analysis, X-ray photoelectron spectroscopy (XPS) and temperature-programmed desorption. Moreover, we study the catalytic performance on the metal-free nitrogen-modified ADD catalysts by means of selective oxidation of benzylic alcohols as a probe reaction. The results indicate that the modified ADD catalysts exhibit a higher catalytic activity than pristine ADD. By correlating XPS data with catalytic measurements, we conclude that the pyridinic nitrogen species plays a pivotal role in the catalytic reaction. Our work provides valuable information on the design of modified carbon materials with more excellent properties. © 2014 American Chemical Society.

Yao X.,Hefei University of Technology | Li D.,CAS Shanghai Institutes for Biological Sciences | Pei G.,CAS Shanghai Institutes for Biological Sciences
Nature Reviews Molecular Cell Biology | Year: 2013

An interactive, intellectual environment with good funding opportunities is essential for the development and success of basic research. The fast-growing economy and investment in science, together with a visionary plan, have attracted foreign scholars to work in China, motivated world-class Chinese scientists to return and strengthened the country's international collaborations. As a result, molecular and cell biology research in China has evolved rapidly over the past decade. © 2013 Macmillan Publishers Limited. All rights reserved.

Shang R.,Tsinghua University | Ji D.-S.,Tsinghua University | Chu L.,Hefei University of Technology | Fu Y.,Hefei University of Technology | Liu L.,Tsinghua University
Angewandte Chemie - International Edition | Year: 2011

Worth its salt: The palladium-catalyzed decarboxylative coupling of the cyanoacetate salt as well as its mono- and disubstituted derivatives with aryl chlorides, bromides, and triflates is described (see scheme). This reaction is potentially useful for the preparation of a diverse array of α-aryl nitriles and has good functional group tolerance. S-Phos=2-(2,6- dimethoxybiphenyl)dicyclohexylphosphine), Xant-Phos=4,5-bis(diphenylphosphino)- 9,9-dimethylxanthene. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Wang X.,Hefei University of Technology | Jiang W.,Hefei University of Technology | Yan Y.,Hefei University of Technology | Gong T.,Hefei University of Technology | And 4 more authors.
Nature Immunology | Year: 2014

The NLRP3 inflammasome functions as a crucial component of the innate immune system in recognizing viral infection, but the mechanism by which viruses activate this inflammasome remains unclear. Here we found that inhibition of the serine-threonine kinases RIP1 (RIPK1) or RIP3 (RIPK3) suppressed RNA virus-induced activation of the NLRP3 inflammasome. Infection with an RNA virus initiated assembly of the RIP1-RIP3 complex, which promoted activation of the GTPase DRP1 and its translocation to mitochondria to drive mitochondrial damage and activation of the NLRP3 inflammasome. Notably, the RIP1-RIP3 complex drove the NLRP3 inflammasome independently of MLKL, an essential downstream effector of RIP1-RIP3-dependent necrosis. Together our results reveal a specific role for the RIP1-RIP3-DRP1 pathway in RNA virus-induced activation of the NLRP3 inflammasome and establish a direct link between inflammation and cell-death signaling pathways.

Song M.,Anhui University of Finance and Economics | An Q.,Hefei University of Technology | Zhang W.,University of Jinan | Wang Z.,Anhui University of Finance and Economics | Wu J.,Hefei University of Technology
Renewable and Sustainable Energy Reviews | Year: 2012

The paper aims to investigate the achievements of the theoretical and practical basis of environmental policy analysis in order to study their works and point out the future possible research direction. It sorts out researches about environmental efficiency assessment and reviews the works about the theory and application of efficiency analysis around the world. It is suggested that environmental efficiency evaluation theory under small samples and DEA method with undesirable outputs will further extend the research on environmental efficiency evaluation. Also, this review confirms that more studies in methods and their applications in this area are in urgent need. © 2012 Elsevier Ltd. All rights reserved.

Zhang S.-L.,Hefei University of Technology | Fu Y.,Hefei University of Technology | Shang R.,Hefei University of Technology | Guo Q.-X.,Hefei University of Technology | Liu L.,Tsinghua University
Journal of the American Chemical Society | Year: 2010

Transition-metal-catalyzed decarboxylative coupling presents a new and important direction in synthetic chemistry. Mechanistic studies on decarboxylative coupling not only improve the understanding of the newly discovered transformations, but also may have valuable implications for the development of more effective catalyst systems. In this work, a comprehensive theoretical study was conducted on the mechanism of Myers' Pd-catalyzed decarboxylative Heck reaction. The catalytic cycle was found to comprise four steps: decarboxylation, olefin insertion, β-hydride elimination, and catalyst regeneration. Decarboxylation was the rate-limiting step, and it proceeded through a dissociative pathway in which Pd(II) mediated the extrusion of CO2 from an aromatic carboxylic acid to form a Pd(II)-aryl intermediate. Further analysis was conducted on the factors that might control the efficiency of Myers' decarboxylative Heck reaction. These factors included Pd salts, ligands, acid substrates, and metals. (1) Regarding Pd salts, PdCl2 and PdBr2 were worse catalysts than Pd(TFA)2, because the exchange of Cl or Br by a carboxylate from Pd was thermodynamically unfavorable. (2) Regarding ligands, DMSO provided the best compromise between carboxyl exchange and decarboxylation. Phosphines and N-heterocarbenes disfavored decarboxylation because of their electron richness, whereas pyridine ligands disfavored carboxyl exchange. (3) Regarding acid substrates, a good correlation was observed between the energy barrier of R-COOH decarboxylation and the R-H acidity. Substituted benzoic acids showed deviation from the correlation because of the involvement of π(substituent)-σ(C ipso-Pd) interaction. (4) Regarding metals, Ni and Pt were worse catalysts than Pd because of the less favorable carboxyl exchange and/or DMSO removal steps in Ni and Pt catalysis. © 2010 American Chemical Society.

Sheng Y.-M.,Hefei University of Technology | Zheng Y.-F.,Hefei University of Technology | Chen R.-X.,Hefei University of Technology | Li Q.,CAS Institute of Geology and Geophysics | Dai M.,Northwest University, China
Lithos | Year: 2012

In-situ SIMS analyses of O and U-Pb isotopes as well as LA-(MC)-ICPMS analyses of trace elements, U-Pb, and Lu-Hf isotopes were carried out for zircon from a quartz vein and its host UHP eclogite in the Dabie orogen. The results are integrated to decipher the effect of aqueous fluid on the new growth of metamorphic zircon and on the recrystallization of protolith zircon during continental subduction-zone metamorphism. Most zircons show distinct core-(mantle)-rim structures in CL images. The rims are unzoned and have low trace element contents, low Th/U ratios of 0.003 to 0.06 and shallow MREE-HREE patterns, and insignificant negative Eu anomalies, indicating their growth from metamorphic fluid. The rims from the vein have concordant U-Pb ages of 222±6 to 212±4Ma, suggesting protracted growth during exhumation of the deeply subducted continental crust. In contrast, the rims from the eclogite gave two groups of concordant U-Pb ages at 221±3 and 208±3Ma, respectively, corresponding to two episodes of fluid action. The all rims have relatively uniformly negative δ 18O values of -2.59 to -1.23‰ for the vein and -3.37 to -0.33‰ for the eclogite, suggesting their growth from negative δ 18O metamorphic fluids of the same origin. The cores exhibit clearly oscillatory or patchy zonation, high trace element contents, high Th/U ratios of 0.13 to 2.12, steep MREE-HREE patterns, and significant negative Eu anomalies. They gave discordia Neoproterozoic upper-intercept U-Pb ages for the both vein and eclogite. Most cores have discordant U-Pb ages and variably positive δ 18O values, with no correlation between the two variables. This suggests non-linear isotope alteration of the protolith zircon by metamorphic recrystallization in the presence of aqueous fluid. The highest δ 18O value of 4.76‰ with the concordant Neoproterozoic U-Pb age is considered as a proxy for the primary δ 18O value for the protolith zircon. In this regard, the cores would crystallize from slightly low δ 18O magmas in the Neoproterozoic, and interacted with the negative δ 18O fluids of metamorphic origin in the Triassic. In particular, the cores in the vein are the xenocrystal that was trapped by the metamorphic fluids from the eclogite. Therefore, the occurrence of the both magmatic cores and metamorphic growth in the vein suggests that sinking of the metamorphic fluids into eclogite factures brought about both the physical transport of protolith zircon and the chemical transport of element Zr during the continental collision. © 2011 Elsevier B.V.

Xiao B.,Hefei University of Technology | Fu Y.,Hefei University of Technology | Xu J.,Hefei University of Technology | Gong T.-J.,Hefei University of Technology | And 3 more authors.
Journal of the American Chemical Society | Year: 2010

(Chemical Equation Presented) Although nitrogen-containing group-directed cyclopalladation reactions have been well-known, Pd(II) insertion into C-H bonds promoted by coordination of an oxygen-only group to the palladium remains rather rare. In the present study, the first cyclopalladation complex formed from a simple phenol ester was characterized by X-ray crystallography. A promising protocol for the ortho C-H activation/aryl-aryl coupling of phenol esters that was not sensitive to moisture or air was then established. The utility of the reaction was demonstrated for the synthesis of useful phenol derivatives. Copyright © 2010 American Chemical Society.

Li F.,Hohai University | Miao Y.,Hohai University | Yang C.,Hefei University of Technology
Research Policy | Year: 2015

Recruiting overseas alumni as faculty within their Chinese alma mater has become a common phenomenon in Chinese universities. This paper studies how the alumni linkage, the connection between alumni faculty members and their alma mater, influences the individual collaborative behaviour of returnee scholars. The results show that alumni faculty are inclined to conduct less intra-institutional collaboration than non-alumni faculty, and the impact of alumni linkage on a scholar's propensity towards international collaboration is not significant. Both results are inconsistent with expectations. The importance of local networking and other factors in Chinese research culture may cause returnee scholars to exhibit such unexpected behaviours in collaborative propensities. Another central finding is that alumni faculty members tend to publish in journals with an average greater impact factor than non-alumni faculty. We therefore argue that alumni linkage has played an important role in bringing about the prosocial behaviour of alumni faculty by strengthening their motivation to pursue quality research, and that the strength of a returnee scholar's local academic network also has a great impact on their tendency towards high impact research. © 2014 Elsevier B.V. All rights reserved.

Yang L.,Chinese Academy of Sciences | Ma L.,Hefei University of Technology | Chen G.,Hefei University of Technology | Liu J.,Chinese Academy of Sciences | Tian Z.-Q.,Xiamen University
Chemistry - A European Journal | Year: 2010

We report herein a method for the ultra-trace detection of TNT on p-aminothiophenol-functionalized silver nanoparticles coated on silver molybdate nanowires based on surface-enhanced Raman scattering (SERS). The method relies on π-donor-acceptor interactions between the π-acceptor TNT and the π-donor p,p′-dimercaptoazobenzene (DMAB), with the latter serving to cross-link the silver nanoparticles deposited on the silver molybdate nanowires. This system presents optimal imprint molecule contours, with the DMAB forming imprint molecule sites that constitute SERS "hot spots". Anchoring of the TNT analyte at these sites leads to a pronounced intensification of its Raman emission. We demonstrate that TNT concentrations as low as 10 -12M can be accurately detected using the described SERS assay. Most impressively, acting as a new type of SERS substrate, the silver/silver molybdate nanowires complex can yield new silver nanoparticles during the detection process, which makes the Raman signals very stable. A detailed mechanism for the observed SERS intensity change is discussed. Our experiments show that TNT can be detected quickly and accurately with ultra-high sensitivity, selectivity, reusability, and stability. The results reported herein may not only lead to many applications in SERS techniques, but might also form the basis of a new concept for a molecular imprinting strategy. SERS substrates: The ultra-trace detection of TNT based on surface-enhanced Raman scattering (SERS) is reported. The method relies on π-donor-acceptor interactions between the π-acceptor TNT and the π-donor p,p′-dimercaptoazobenzene (DMAB), with the latter serving to cross-link silver nanoparticles deposited on the surface of silver molybdate nanowires (see scheme). © 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Chen L.,National Taiwan University | Chen L.,Hefei University of Technology | Chen K.-J.,National Taiwan Normal University | Hu S.-F.,National Taiwan Normal University | Liu R.-S.,National Taiwan University
Journal of Materials Chemistry | Year: 2011

A red phosphor is desired to improve the color rendering index (Ra) of white light-emitting diodes (LEDs). Instead of developing a novel red phosphor individually, this work exploits a special yellow phosphor that contains red and green components to be matched with blue phosphor to produce white light. The desired emission color of yellow phosphor is tuned up by tailoring the green emission of Bi3+ and the red emission of Eu3+, and the luminescence efficiency and the thermal stability of luminescence are maximized by optimizing the composition of the host in the GdVO4-YVO 4 system. A dynamic and virtual variation of samples emission color and intensity with Bi3+, Eu3+, Y3+ and Gd 3+ concentrations and excitation wavelengths is clearly displayed in the luminescence images of the combinatorial libraries. The production of white light with high color rendering is demonstrated by preparing a practical white LED with a Ra of up to 90 from commercially available blue phosphor and optimized yellow phosphor. © The Royal Society of Chemistry 2011.

He Y.,CAS Institute of Geology and Geophysics | Wen L.,State University of New York at Stony Brook | Wen L.,Hefei University of Technology
Journal of Geophysical Research: Solid Earth | Year: 2012

We determine the geographical boundary and average shear velocity structure of the Pacific Anomaly at the base of the mantle based on travel time analysis of ScSH-SH and ScS2 (ScSScS)-SS phases and waveform modeling results. We further constrain the detailed geometry of the northern Anomaly around (20°N, - 170°E) and its transition to the surrounding high velocity region along three perpendicular cross sections on the basis of forward waveform modeling of the observed direct S and ScS phases. The observed differential travel-time residuals and waveform modeling results allow the whole geographic boundary of the Anomaly to be delineated and the area of the base of the Anomaly is estimated to be 1.9 × 10 km. The maximum shear velocity perturbation inside the Anomaly reaches -5% in the lowermost 500 km of the mantle. Waveform analysis suggests that the northern Anomaly reaches 450 km above the CMB with both steeply and shallowly dipping edges and its basal layer extends beneath the surrounding mantle with the degree of extension changing rapidly across a small distance. The inferred characteristics of the Anomaly support the previous suggestion that the Pacific Anomaly represents a chemical anomaly. However, unlike the inferred features of the African Anomaly pointing to an ancient compositionally distinct and geologically stable anomaly, the existence of several separated piles extending into the mid-lower mantle, the complex morphology of the piles with both steeply and shallowly dipping edges and the presence of many ultra-low velocity zones at its base suggest that the Pacific Anomaly likely possesses varying intrinsic compositions and exhibits complex interaction with the surrounding mantle. © 2012. American Geophysical Union. All Rights Reserved.

Li N.,CAS Shenyang Institute of Metal Research | Li N.,Hefei University of Technology | Zhou G.,CAS Shenyang Institute of Metal Research | Li F.,CAS Shenyang Institute of Metal Research | And 2 more authors.
Advanced Functional Materials | Year: 2013

Flexible energy-storage devices have attracted growing attention with the fast development of bendable electronic systems. Thus, the search for reliable electrodes with both high mechanical flexibility and excellent electron and lithium-ion conductivity has become an urgent task. Carbon-coated nanostructures of Li4Ti5O12 (LTO) have important applications in high-performance lithium ion batteries (LIBs). However, these materials still need to be mixed with a binder and carbon black and pressed onto metal substrates or, alternatively, by be deposited onto a conductive substrate before they are assembled into batteries, which makes the batteries less flexible and have a low energy density. Herein, a simple and scalable process to fabricate LTO nanosheets with a N-doped carbon coating is reported. This can be assembled into a film which can be used as a binder-free and flexible electrode for LIBs that does not require any current collectors. Such a flexible electrode has a long life. More significantly, it exhibits an excellent rate capability due to the thin carbon coating and porous nanosheet structures, which produces a highly conductive pathway for electrons and fast transport channels for lithium ions. A self-standing and flexible Li4Ti5O12 electrode is assembled via a vacuum filtration process of Li4Ti 5O12 nanosheets with N-doped carbon coating. This flexible electrode shows an excellent rate capability and a significantly improved cycling performance. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Sharma S.,Hefei University of Technology | Sharma S.,DAV University
Physica A: Statistical Mechanics and its Applications | Year: 2015

In this paper, a new two-lane lattice hydrodynamic traffic flow model is proposed by considering the aggressive or timid characteristics of driver's behavior. The effect of driver's characteristic on the stability of traffic flow is examined through linear stability analysis. It is shown that for both the cases of lane changing or without lane changing the stability region significantly enlarges (reduces) as the proportion of aggressive (timid) drivers increases. To describe the propagation behavior of a density wave near the critical point, nonlinear analysis is conducted and mKdV equation representing kink-antikink soliton is derived. The effect of anticipation parameter with more aggressive (timid) drivers is also investigated and found that it has a positive (negative) effect on the stability of two-lane traffic flow dynamics. Simulation results are found consistent with the theoretical findings which confirm that the driver's characteristics play a significant role in a two-lane traffic system. © 2014 Elsevier B.V. All rights reserved.

Ke L.,Qualcomm | Ramamoorthy A.,Iowa State University | Wang Z.,Iowa State University | Yin H.,Hefei University of Technology
IEEE Transactions on Information Theory | Year: 2012

We consider a single-hop interference network with K transmitters and J receivers, all having M antennas. Each transmitter emits an independent message and each receiver requests an arbitrary subset of the messages. This generalizes the well-known K -user M-antenna interference channel, where each message is requested by a unique receiver. For our setup, we derive the degrees of freedom (DoF) region. The achievability scheme generalizes the interference alignment schemes proposed by Cadambe and Jafar. In particular, we achieve general points in the DoF region by using multiple base vectors and aligning all interferers at a given receiver to the interferer with the largest DoF. As a byproduct, we obtain the DoF region for the original interference channel. We also discuss extensions of our approach where the same region can be achieved by considering a reduced set of interference alignment constraints, thus reducing the time-expansion duration needed. The DoF region for the considered system depends only on a subset of receivers whose demands meet certain characteristics. The geometric shape of the DoF region is also discussed. © 1963-2012 IEEE.

Yang C.-T.,Tsinghua University | Zhang Z.-Q.,Tsinghua University | Liang J.,Hefei University of Technology | Liu J.-H.,Tsinghua University | And 3 more authors.
Journal of the American Chemical Society | Year: 2012

Practical catalytic cross-coupling of secondary alkyl electrophiles with secondary alkyl nucleophiles under Cu catalysis has been realized. The use of TMEDA and LiOMe is critical for the success of the reaction. This cross-coupling reaction occurs via an S N2 mechanism with inversion of configuration and therefore provides a general approach for the stereocontrolled formation of C-C bonds between two tertiary carbons from chiral secondary alcohols. © 2012 American Chemical Society.

Xu R.,Hefei University of Technology | Xu R.,University of Tennessee at Knoxville | Chen H.,Hefei University of Technology | Li X.,University of Tennessee at Knoxville
Computers and Operations Research | Year: 2012

This paper investigates the problem of minimizing makespan on a single batch-processing machine, and the machine can process multiple jobs simultaneously. Each job is characterized by release time, processing time, and job size. We established a mixed integer programming model and proposed a valid lower bound for this problem. By introducing a definition of waste and idle space (WIS), this problem is proven to be equivalent to minimizing the WIS for the schedule. Since the problem is NP-hard, we proposed a heuristic and an ant colony optimization (ACO) algorithm based on the theorems presented. A candidate list strategy and a new method to construct heuristic information were introduced for the ACO approach to achieve a satisfactory solution in a reasonable computational time. Through extensive computational experiments, appropriate ACO parameter values were chosen and the effectiveness of the proposed algorithms was evaluated by solution quality and run time. The results showed that the ACO algorithm combined with the candidate list was more robust and consistently outperformed genetic algorithm (GA), CPLEX, and the other two heuristics, especially for large job instances. © 2011 Elsevier Ltd. All rights reserved.

Ma H.,Hefei University of Technology | Liu J.,Hefei University of Technology | Liang W.,Xiamen University
Journal of Chemical Theory and Computation | Year: 2012

Efficient quantum dynamical and electronic structure approaches are presented to calculate resonance Raman spectroscopy (RRS) with inclusion of Herzberg-Teller (HT) contribution and mode-mixing (Duschinsky) effect. In the dynamical method, an analytical expression for RRS in the time domain is proposed to avoid summation over the large number of intermediate vibrational states. In the electronic structure calculations, the analytic energy-derivative approaches for the excited states within the time-dependent density functional theory (TDDFT), developed by us, are adopted to overcome the computational bottleneck of excited-state gradient and Hessian calculations. In addition, an analytic calculation to the geometrical derivatives of the transition dipole moment, entering the HT term, is also adopted. The proposed approaches are implemented to calculate RR spectra of a few of conjugated systems, phenoxyl radical, 2-thiopyridone in water solution, and free-base porphyrin. The calculated RR spectra show the evident HT effect in those π-conjugated systems, and their relative intensities are consistent with experimental measurements. © 2012 American Chemical Society.

Xu R.,Hefei University of Technology | Chen H.,Hefei University of Technology | Li X.,University of Tennessee at Knoxville
International Journal of Production Economics | Year: 2013

This research aims to minimize the bi-criteria of makespan and maximum tardiness on a set of identical batch-processing machines arranged in parallel. Each machine can process multiple jobs simultaneously as long as the machine capacity is not exceeded. Each job is defined by its processing time, ready time, due date, and size. The processing time and ready time of a batch are represented by the largest processing time and release time among all jobs in the batch, respectively. For this problem, a scheduling algorithm based on the framework of a multi-objective ant colony optimization (MOACO) approach called a Pareto-based ant colony system (PACS) was developed. Based on the constructive characteristics of PACS, a new mechanism of solution construction was introduced so that the proposed algorithm had the ability to explore the entire solution space. Moreover, corresponding to the new construction mechanism, a candidate list strategy and a form of dynamic heuristic information were developed to reduce the search space and direct the search toward the promising regions, respectively. Through extensive computational experiments with various problem instances, the effectiveness of the proposed algorithm was evaluated by measuring the computational efficiency and solution quality. The experiment results demonstrated that PACS had a superior performance compared to other benchmark algorithms, especially for large job instances. © 2013 Elsevier B.V.

Chen R.-X.,Hefei University of Technology | Zheng Y.-F.,Hefei University of Technology | Xie L.,CAS Institute of Geology and Geophysics
Lithos | Year: 2010

Simultaneous in-situ analyses of trace elements, U-Th-Pb and Lu-Hf isotopes were carried out on distinct domains of zircons in ultrahigh-pressure (UHP) eclogite-facies metamorphic rocks from the main hole of the Chinese Continental Scientific Drilling (CCSD) in the Sulu orogen. For the first time, trace elements are directly linked to Lu-Hf isotopes in metamorphic zircons with reference to their U-Pb dates. This enables methodological integration to distinguish four types of metamorphic zircon: solid-state, replacement and dissolution recrystallizations of protolith zircons, and new growth from the aqueous fluid. Metamorphically grown zircons are characterized by concordant U-Pb ages for the metamorphism, flat HREE patterns typical of the garnet effect, low contents of REE (especially HREE), Y, Nb + Ta and Th + U, high contents of Hf, low (Lu/Gd)N, Lu/Hf and Th/U (< 0.1) ratios, and elevated 176Hf/177Hf ratios relative to solid-state recrystallized zircons. This suggests the effects of both garnet and fluid on the growth of metamorphic zircons. In contrast, metamorphic recrystallization has reset the U-Th-Pb isotope system of protolith zircons to different extents, depending on the extents of fluid action during metamorphism. Solid-state recrystallized zircons exhibit the lowest degrees of resetting and thus almost inherit all geochemical features from the protolith zircons, which are characterized by discordant U-Pb ages close to or below the protolith age, steep MREE-HREE patterns typical of magmatic origin, high contents of trace elements and their ratios, and low 176Hf/177Hf ratios. On the other hand, dissolution recrystallized zircons show the highest degrees of reworking and thus have concordant or nearly concordant U-Pb ages for the metamorphism, steep MREE-HREE patterns, lowered contents of trace elements such as REE, Th, U, Y, Nb, Ta and Ti relative to the protolith zircons, and almost unchanged Hf isotope ratios. Replacement recrystallized zircons display intermediate degrees of reworking and thus have their many features of elements and isotopes in between. While the metamorphic growth in the presence of both garnet and fluid is characterized by both depletion of HREE with flat pattern and the low contents of trace elements, the metamorphic recrystallization in the presence of aqueous fluid is indicated by gradual decreases of MREE to HREE without the flat HREE pattern. Therefore, the simultaneous in-situ analyses of metamorphic zircons have the advantage over single-term analyses in making distinction between the new growth and the different types of recrystallization. © 2009 Elsevier B.V. All rights reserved.

Shcherbakov R.V.,Harvard - Smithsonian Center for Astrophysics | Huang L.,Academia Sinica, Taiwan | Huang L.,Key Laboratory for Research in Galaxies and Cosmology | Huang L.,Hefei University of Technology
Monthly Notices of the Royal Astronomical Society | Year: 2011

The rising number of polarized observations of relativistic sources necessitates a correct theory for proper model fitting. The equations for general relativistic (GR) polarized radiative transfer are derived starting from the Boltzmann equation and basic ideas of general relativity. The derivation is aimed at providing a practical guide to reproducing the synchrotron part of radio and submillimetre emission from low-luminosity active galactic nuclei (LLAGNs), in particular Sgr A*, and jets. A recipe for the fast exact calculation of cyclo-synchrotron emissivities, absorptivities, Faraday rotation and conversion coefficients is given for isotropic particle distributions. The multitude of physical effects influencing simulated spectra is discussed. The application of the prescribed technique is necessary to determine the black hole spin in LLAGNs. The observations of total flux, linear and circular polarization fractions, and electric vector position angle as functions of the observed frequency could substantially constrain the absolute value and orientation of spin. © 2010 The Authors Monthly Notices of the Royal Astronomical Society © 2010 RAS.

Ren Y.-X.,CAS Shanghai Institutes for Biological Sciences | Lu R.-D.,Hefei University of Technology | Gong L.,Hefei University of Technology
Annalen der Physik | Year: 2015

A digital micromirror device (DMD) is a product of micromechanics. The DMD employs numerous micromirrors as the actuating components to switch small portions of light on and off. During the past few decades, such devices have been widely applied in digital light processing technology. The expanding range of applications makes the DMD increasingly important in various research aspects. Recent advances demonstrate that the DMD is potentially better than the traditional liquid crystal spatial light modulator in speed, spectrum sensitivity, and polarization modulation. These characteristics have been verified in a series of recently reported experiments. This review summarizes the related theory, experimental techniques, and applications for wavefront shaping with DMDs in both statically shaping various spatial modes and dynamically compensating for wavefront distortion caused by the scattering medium. © 2015 by WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Dai L.-Q.,Hefei University of Technology | Zhao Z.-F.,Hefei University of Technology | Zhao Z.-F.,CAS Institute of Geology and Geophysics | Zheng Y.-F.,Hefei University of Technology
Gondwana Research | Year: 2015

Continental collision is generally developed from oceanic subduction to continental subduction. Recycling of both oceanic and continental crustal materials is expected to occur in the same subduction zone. This is demonstrated by an integrated study of major-trace elements and stable-radiogenic isotopes in postcollisional mafic igneous rocks from the Hong'an-Dabie orogens, east-central China. Mafic dykes in the Hong'an orogen exhibit OIB-like trace element distribution patterns, high Nb/U and TiO2/Al2O3 ratios, relatively depleted radiogenic isotope compositions with consistently high εNd(t) values of -1.8 to 4.5 and low initial 87Sr/86Sr ratios of 0.7040 to 0.7050. They are significantly different from mafic intrusives in the Dabie orogen that exhibit arc-like trace element distribution patterns, low Nb/U and TiO2/Al2O3 ratios, relatively enriched radiogenic isotope compositions with low εNd(t) values of -2.3 to -20.7 and high initial 87Sr/86Sr ratios of 0.7061 to 0.7114. In addition, whole-rock and zircon Hf isotope compositions are decoupled in the Hong'an mafic dykes but coupled in the Dabie mafic intrusives. Nevertheless, zircon O isotope compositions exhibit similar variations for the two occurrences of mafic rocks. These observations are interpreted as indicating significant differences in the nature of mantle sources between the Hong'an and Dabie mafic rocks. Two types of melt-peridotite reaction are assumed to occur in oceanic and continental subduction channels, respectively, during continental collision. Reaction of juvenile subcontinental lithospheric mantle (SCLM) peridotite with felsic melt derived from subducting oceanic basalt and sediment before continental subduction would generate the mantle source for the Hong'an mafic dykes, whereas reaction of ancient SCLM peridotite with felsic melt from subducting continental crust would generate the mantle source for the Dabie mafic intrusives. While such contrasting types of melt-peridotite reaction at the slab-mantle interface are responsible for the systematic differences in the geochemical compositions of mantle sources, the incorporation of crust-derived felsic melts into the mantle wedge result in the similar lithology of non-peridotite such as pyroxenite and hornblendite. Therefore, the two types of slab-mantle interaction record the tectonic transition from oceanic subduction to continental subduction in the course of continental collision. The nature of slab-mantle interaction in subduction channel is a key to the origin of mantle sources for postcollisional mafic igneous rocks in continental collision orogens. © 2013 International Association for Gondwana Research.

News Article | February 15, 2017
Site: www.bbc.co.uk

Scientists have uncovered the first evidence of live births in the group of animals that includes dinosaurs, crocodiles and birds. All examples of this group, known as the Archosauromorpha, lay eggs. This led some scientists to wonder whether there was something in their biology that prevented live births. But examination of the fossil remains of a very long-necked, 245 million-year-old marine reptile from China revealed it was carrying an embryo. Jun Liu, first author of the new study in Nature Communications, told BBC News that the animal would have measured between three and four metres long, with a neck that was about 1.7m long. The embryo may have been around half a metre long and is positioned inside the rib cage of the adult Dinocephalosaurus fossil, which was discovered in 2008 in Luoping County, Yunnan Province in southern China. Researchers had to consider whether the smaller animal might have been part of the adult's last meal. But it's facing forward, whereas swallowed prey generally face backwards because predators consume the animal head first to help it go down the throat. Another line of evidence in favour of the live birth idea is that the small reptile inside the mother is clearly an example of the same species. Co-author Prof Mike Benton, from the University of Bristol, told BBC News that the fossil was important because the Archosauromorpha form one of three large groupings of land-based vertebrates (backboned animals), each including about 10,000 species. Since we now know that no fundamental biological barrier to live births exists in this group, palaeontologists would be "looking very closely" at other fossils. He suggested one target would be a group of aquatic crocodile relatives - whose mode of reproduction was not well known. Prof Liu, from Hefei University of Technology in China, said the discovery pushes back evidence of reproductive biology in the archosauromorphs by 50 million years. The mode of reproduction in Dinocephalosaurus also points to how the sex of its offspring was determined. Co-author Prof Chris Organ, from Montana State University, added: "Some reptiles today, such as crocodiles, determine the sex of their offspring by the temperature inside the nest. "We identified that Dinocephalosaurus, a distant ancestor of crocodiles, determined the sex of its babies genetically, like mammals and birds." Prof Benton explained: "This combination of live birth and genotypic sex determination seems to have been necessary for animals such as Dinocephalosaurus to become aquatic. "It's great to see such an important step forward in our understanding of the evolution of a major group coming from a chance fossil find in a Chinese field." The possibility that an eggshell once surrounded the embryo but was not preserved in fossilisation could not be ruled out, said Prof Benton. But living Archosauromorphs all lay eggs very early in embryonic development, whereas this embryo is very advanced, with well developed bones. Furthermore, the team says Dinocephalosaurus's long neck and other features of its anatomy suggest it could not have manoeuvred easily out of the water, meaning a reproductive strategy like that of turtles - which lay eggs on land before returning to the water - was probably not an option.

News Article | February 15, 2017
Site: www.nanotech-now.com

Home > Press > Researchers optimize the assembly of micro-/meso-/macroporous carbon for Li-S batteries Abstract: Li-S batteries are considered as promising alternatives for Li-ion batteries in the new generation of energy storages, due to high specific capacity (1675 mAh/g) and energy density (2600 mWh/g) of sulfur. But the poor conductivity of sulfur and severe shuttle effect of reaction intermediates destory the stability of this system. A variety of porous carbon materials have been applied as sulfur host to improve the performances of Li-S batteries for high conductivity, specific surface area and absorption effect. However, what kind of porous carbon would be the optimal choice to accommodate active material? And Which characteristic of carbon pores should be emphasized? A team of researchers from the School of Materials Science and Engineering and School of Electronic Science and Applied Physics at Hefei University of Technology demostrated that pore size distribution substantially influences the performances of cathode rather than specific surface area and total pore volume. Furthermore, an optimized assembly of micro/meso/macroporous carbon enables cathode present greatly improved electrochemical performances, in which micropore-volume-ratio to the total pore volume dominates cycling stability of batteries, meso/macropore-volume-ratio influences spaces for sulfur loading and channels to ion transfer. This research provides a direction of fabricating porous materials for energy storage.The report appears in the latest issue of the journal NANO. Based on the traditional S/C cathode, the effects of surface area, total pore volume and pore size distribution of carbon pores on performances of Li-S batteries are compared. In addition, on the premise of identically high sulfur content, the relation of the micro/meso/macropore volume ratio with the capacity, voltage plateau, rate capability, and cycle stability of Li-S battery are investigated. Among the samples, the porous carbon possesses the largest micropore volume ratio of 47.54% while a medium specific surface area of 1217 m2/g and inferior total pore volume of 0.54 cm3/g presents the highest initial discharge specific capacity of 1327 mAh/g and retention of 630 mAh/g over 100 cycles at 0.2C rate along with the best rate capability. The conclusions in this study can be directly applied in material fabrication for other systems of energy storage and even as criterions for further modification of Li-S batteries based on carbon material. This research was supported by the "Strategic Priority Research Program" of the Chinese Academy of Science (NO. XDA03040000) and the Fundamental Research Funds for the Central Universities (NO. 103-4115100010) of China. About World Scientific World Scientific Publishing is a leading independent publisher of books and journals for the scholarly, research, professional and educational communities. The company publishes about 600 books annually and about 130 journals in various fields. World Scientific collaborates with prestigious organisations like the Nobel Foundation, US National Academies Press, as well as its subsidiary, the Imperial College Press, amongst others, to bring high quality academic and professional content to researchers and academics worldwide. To find out more about World Scientific, please visit www.worldscientific.com. For more information, please click If you have a comment, please us. Issuers of news releases, not 7th Wave, Inc. or Nanotechnology Now, are solely responsible for the accuracy of the content.

What this evidence of live birth from a 250-million-year-old fossil of the long-necked relative of dinosaurs found in China tells us? More than an evidence of live birth, the discovery has its profound effect on the present knowledge about the reproductive biology among Archosauromorphs. The fish-eating Dinocephalosaurus fossil, an archosauromorp, thrived during the Middle Triassic Period in the shallow regions of South China Sea. The researchers were "excited" when they discovered the pregnant fossil, according to Prof. Jun Liu, lead researcher from Hefei University of Technology in China. The animal may have been three to four meters long with a neck that is about 1.7 meters long. "Live birth is well-known in mammals, where the mother has a placenta to nourish the developing embryo" Prof. Jonathan Aitchison, head of the University of Queensland School of Earth and Environmental Sciences, said. This mode of reproduction, however, has not been known among the third major group of living land vertebrate, crocodiles, and birds until recently. The evolution of live birth happens independently among mammals and bigger groups of lizards and snakes, based on an article published in Nature Communications on Feb. 14. However, it was not known among Archosauromorphs, represented today by crocodiles and birds. Live birth — technically known as viviparity — among scaled reptiles has evolved at least 115 times despite the complex process of the transition. This transition from egg-laying — or oviparity — to live birth involved the changes of the mother's form and structure, internal organs, and behavior leading to the feeding of embryo by the mother through a placenta. It was thought that live birth was common only among lizards and snakes but not among the wider group living land vertebrate composed of crocodiles and birds. Not until the discovery of the pregnant fossil. The embryo, measured about half a meter long, was inside the rib cage of the adult Dinocephalosaurus fossil. At first, the researchers were not certain if the smaller fossil was the animal's last meal or unborn baby. Upon closer inspection and analysis, it was established that the fossil inside the adult animal was indeed the unborn baby. Professor Chris Organ, a fellow researcher from Montana State University, said analysis of the evolution had shown the live birth, in this case, was due to genetic sex determination. "Some reptiles today, such as crocodiles, determine the sex of their offspring by the temperature inside the nest," he said. The recent findings have shown that "Dinocephalosaurus, a distant ancestor of crocodiles, determined the sex of its babies genetically, like mammals and birds." Liu said the discovery "pushes back evidence of reproductive biology among Archosauromorphs" by around 50 million years. The discovery of the 250-million-year-old fossil has furnished "information on reproductive biology of archosauromorphs before the Jurassic Period," Liu said Archosauromorphs was one of the three large groups of land-based vertebrates. Each of the three groups numbered around 10,000 species. The recent finding shows that the long-necked animal could achieve live birth. Prof Mike Benton, co-author from the University of Bristol, told BBC News that palaeontologists would now be "looking very closely" at other fossils of animal group whose information on how they reproduction is not yet known. One target is the group of aquatic crocodile, Benton said. © 2017 Tech Times, All rights reserved. Do not reproduce without permission.

Mei Y.,Hefei University of Technology | Tang K.,Hefei University of Technology | Yao X.,Hefei University of Technology | Yao X.,University of Birmingham
IEEE Transactions on Systems, Man, and Cybernetics, Part B: Cybernetics | Year: 2011

This paper investigates the Periodic Capacitated Arc Routing Problem (PCARP), which is often encountered in the waste collection application. PCARP is an extension of the well-known Capacitated Arc Routing Problem (CARP) from a single period to a multi-period horizon. PCARP is a hierarchical optimization problem which has a primary objective (minimizing the number of vehicles $mnv$) and a secondary objective (minimizing the total cost $tc$). An important factor that makes PCARP challenging is that its primary objective $mnv$ is little affected by existing operators and thus difficult to improve. We propose a new Memetic Algorithm (MA) for solving PCARP. The MA adopts a new solution representation scheme and a novel crossover operator. Most importantly, a Route-Merging (RM) procedure is devised and embedded in the algorithm to tackle the insensitive objective $mnv$. The MA with RM (MARM) has been compared with existing meta-heuristic approaches on two PCARP benchmark sets and a real-world data set. The experimental results show that MARM obtained better solutions than the compared algorithms in much less time, and even updated the best known solutions of all the benchmark instances. Further study reveals that the RM procedure plays a key role in the superior performance of MARM. © 2006 IEEE.

Li P.,CAS Institute of Automation | Wang M.,Hefei University of Technology | Cheng J.,CAS Institute of Automation | Xu C.,CAS Institute of Automation | Lu H.,CAS Institute of Automation
IEEE Transactions on Multimedia | Year: 2013

The ability of fast similarity search in a large-scale dataset is of great importance to many multimedia applications. Semantic hashing is a promising way to accelerate similarity search, which designs compact binary codes for a large number of images so that semantically similar images are mapped to close codes. Retrieving similar neighbors is then simply accomplished by retrieving images that have codes within a small Hamming distance of the code of the query. Among various hashing approaches, spectral hashing (SH) has shown promising performance by learning the binary codes with a spectral graph partitioning method. However, the Euclidean distance is usually used to construct the graph Laplacian in SH, which may not reflect the inherent distribution of the data. Therefore, in this paper, we propose a method to directly optimize the graph Laplacian. The learned graph, which can better represent similarity between samples, is then applied to SH for effective binary code learning. Meanwhile, our approach, unlike metric learning, can automatically determine the scale factor during the optimization. Extensive experiments are conducted on publicly available datasets and the comparison results demonstrate the effectiveness of our approach. © 1999-2012 IEEE.

He L.,Zhejiang University | Zhang L.,Wenzhou University | Liang H.,Hefei University of Technology
Polymer | Year: 2010

Mixtures of diblock copolymers (DBCPs) and mono- or bidisperse nanorods (NRs), are systematically investigated via dissipative particle dynamics simulations. For the mixtures of DBCPs and monodisperse NRs, we investigate the effects of the nanorod (NR) volume fraction, NR length, and interaction strength between blocks and NRs on the self-assembly of the composites. For the mixtures of DBCPs and bidisperse NRs in which the NRs are different in length, the binary NRs with varied compositions can induce various morphological transitions, as well as present the uniform orientations and discriminative distributions. The inherent mechanism for driving such rich phase behaviors can be further exploited on the basis of considering the enthalpic and entropic effects. The results provide some guidelines for engineering nanocomposites with the desired morphologies and functions. © 2010 Elsevier Ltd.

Xu Y.,Hefei University of Technology | Zheng X.,Hefei Normal University | Yu H.,Hefei University of Technology | Hu X.,Hefei University of Technology
Bioresource Technology | Year: 2014

This paper investigated a novel hydrothermal liquefaction process of Chlorella pyrenoidosa catalyzed by Ce/HZSM-5. The chemical groups and components of the residues of C. pyrenoidosa were analyzed by Fourier transform infrared spectrometry and Gas Chromatograph-Mass Spectrometer. The crystal structure and micro surface topography of C. pyrenoidosa before and after catalytic liquefaction were characterized by X-ray diffraction and Scanning electron microscopy, respectively. The experimental results showed that the catalytic cracking effects of Ce/HZSM-5 were superior to that of HZSM-5 as a liquefaction catalyst of C. pyrenoidosa. Compared with HZSM-5, Ce/HZSM-5 has a significantly enhanced Lewis acid active center, smaller particle size, larger specific surface, and highly dispersed Ce4O7 with trivalent and tetravalent cerium in the zeolite skeleton channel that accelerate the catalytic liquefaction of C. pyrenoidosa. The rare earth modified zeolite Ce/HZSM-5 exhibits good potential and a beneficial nature for the preparation of bio-oil from microalgae with high efficiency. © 2014 Elsevier Ltd.

Cong H.-P.,Suzhou University of Science and Technology | Cong H.-P.,Hefei University of Technology | Chen J.-F.,Suzhou University of Science and Technology | Yu S.-H.,Suzhou University of Science and Technology
Chemical Society Reviews | Year: 2014

Due to the outstanding physicochemical properties arising from its truly two-dimensional (2D) planar structure with a single-atom thickness, graphene exhibits great potential for use in sensors, catalysts, electrodes, and in biological applications, etc. With further developments in the theoretical understanding and assembly techniques, graphene should enable great changes both in scientific research and practical industrial applications. By the look of development, it is of fundamental and practical significance to translate the novel physical and chemical properties of individual graphene nanosheets into the macroscale by the assembly of graphene building blocks into macroscopic architectures with structural specialities and functional novelties. The combined features of a 2D planar structure and abundant functional groups of graphene oxide (GO) should provide great possibilities for the assembly of GO nanosheets into macroscopic architectures with different macroscaled shapes through various assembly techniques under different bonding interactions. Moreover, macroscopic graphene frameworks can be used as ideal scaffolds for the incorporation of functional materials to offset the shortage of pure graphene in the specific desired functionality. The advantages of light weight, supra-flexibility, large surface area, tough mechanical strength, and high electrical conductivity guarantee graphene-based architectures wide application fields. This critical review mainly addresses recent advances in the design and fabrication of graphene-based macroscopic assemblies and architectures and their potential applications. Herein, we first provide overviews of the functional macroscopic graphene materials from three aspects, i.e., 1D graphene fibers/ribbons, 2D graphene films/papers, 3D network-structured graphene monoliths, and their composite counterparts with either polymers or nano-objects. Then, we present the promising potential applications of graphene-based macroscopic assemblies in the fields of electronic and optoelectronic devices, sensors, electrochemical energy devices, and in water treatment. Last, the personal conclusions and perspectives for this intriguing field are given. © 2014 the Partner Organisations.

Wang L.-L.,Hefei University of Technology | Wang J.-Q.,Hefei University of Technology | Zheng Z.-X.,Chinese Research Academy of Environmental Sciences | Xiao P.,Chinese Research Academy of Environmental Sciences
Journal of Hazardous Materials | Year: 2010

A sensitive and simple method for high-performance liquid chromatography (HPLC) determination of traces of chromium species in lake sediments after preconcentration by cloud point extraction (CPE) has been developed. Simultaneous preconcentration of Cr(III) and Cr(VI) in sediment samples was achieved by CPE with 1-(2-thiazolylazo)-2-naphthol (TAN) as the chelating agent and non-ionic surfactant octylphenoxypolyethoxyethanol (Triton X-114) as the extractant. Baseline separation of the TAN chelates of Cr(III) and Cr(VI) was realized on a RP-C18 column by using a mixture of methanol-water (69:31, v/v) solution and 4.5mmolL-1 CTMAB buffered with 0.03molL-1 NaAc-HAc solution (pH 5.5) as the mobile phase at a flow rate of 0.8mLmin-1. The variables affecting the complexation and extraction steps were examined. The precision (R.S.D.) for seven replicate injections of a mixture of 100μgL-1 of Cr(III) and Cr(VI) was 1.2 and 0.9% for the retention time, 4.7 and 2.7% for the peak area, respectively. The concentration factor was 45 for Cr(III) and 40 for Cr(VI). The detection limit (LOD) of this method, calculated as three times the standard deviation of the blank signals was 7.5μgL-1 for Cr(III) and 3.5μgL-1 for Cr(VI), respectively. The proposed procedure was applied to the speciation of chromium in sediment samples with satisfactory results. © 2009 Elsevier B.V.

Zhou F.,Suzhou University of Science and Technology | Xin S.,Suzhou University of Science and Technology | Xin S.,Hefei University of Technology | Liang H.-W.,Suzhou University of Science and Technology | And 2 more authors.
Angewandte Chemie - International Edition | Year: 2014

Traditional lithium-ion batteries that are based on layered Li intercalation electrode materials are limited by the intrinsically low theoretical capacities of both electrodes and cannot meet the increasing demand for energy. A facile route for the synthesis of a new type of composite nanofibers, namely carbon nanofibers decorated with molybdenum disulfide sheets (CNFs@MoS2), is now reported. A synergistic effect was observed for the two-component anode, triggering new electrochemical processes for lithium storage, with a persistent oxidation from Mo (or MoS2) to MoS3 in the repeated charge processes, leading to an ascending capacity upon cycling. The composite exhibits unprecedented electrochemical behavior with high specific capacity, good cycling stability, and superior high-rate capability, suggesting its potential application in high-energy lithium-ion batteries. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Ke F.,Suzhou University of Science and Technology | Ke F.,Hefei University of Technology | Qiu L.-G.,Anhui University | Zhu J.,Suzhou University of Science and Technology | Zhu J.,Hefei University of Technology
Nanoscale | Year: 2014

Separation and recycling of catalysts after catalytic reactions are critically required to reduce the cost of catalysts as well as to avoid the generation of waste in industrial applications. In this work, we present a facile fabrication and characterization of a novel type of MOF-based porous catalyst, namely, Fe3O4@MIL-100(Fe) core-shell magnetic microspheres. It has been shown that these catalysts not only exhibit high catalytic activities for the Claisen-Schmidt condensation reactions under environmentally friendly conditions, but remarkably, they can be easily separated and recycled without significant loss of catalytic efficiency after being used for many times. Therefore, compared to other reported catalysts used in the Claisen-Schmidt condensation reactions, these catalysts are green, cheap and more suitable for large scale industrial applications. © 2013 The Royal Society of Chemistry.

Wang L.,University of Texas at Austin | Lu Y.,University of Texas at Austin | Liu J.,State University of New York at Stony Brook | Xu M.,University of Texas at Austin | And 3 more authors.
Angewandte Chemie - International Edition | Year: 2013

Sodium manganese hexacyanoferrates (NMHFCs) synthesized in aqueous solution at room temperature show high reversible capacity and outstanding rate capability as cathodes for a rechargeable sodium-ion battery (SIB). Earth-abundant elements and a low-cost synthesis route make these NMHFCs promising cathodes for SIBs, independent of natural lithium sources. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Wang F.,Hefei University of Technology | Liu S.-A.,China University of Geosciences | Li S.,Hefei University of Technology | Li S.,China University of Geosciences | He Y.,China University of Geosciences
Lithos | Year: 2013

The petrogenesis of Early Cretaceous adakitic intrusions in the Lower Yangtze River belt (LYRB), central-eastern China, and their genetic association with Cu-Au mineralization have recently been debated. This study presented integrated in-situ zircon U-Pb-Hf-O isotopic and trace elemental data for the LYRB adakites, and a comparison with ore-barren adakites from the south Tan-Lu fault (STLF) adjacent to the LYRB. Magmatic zircons from these two series of intrusions have U-Pb ages of 145-132Ma and 136-132Ma respectively. The STLF zircons have δ18O ranging from 5.6 to 6.7% and εHf(t) from -28.8 to -16.4, plotted within the range of global lower crustal metabasaltic xenoliths, consistent with low-radiogenic Pb of the host adakitic rocks. In contrast, both Hf and O isotopic compositions of zircons from the LYRB are greatly variable with heavier δ18O (4.7 to 9.6%) and higher εHf(t) values (-25.5 to +2.0) compared with the STLF series. The co-variations of Hf-O isotopes in the LYRB series reflect source heterogeneity as a result of mixing of basaltic oceanic crust with sediments (10-20%), consistent with high-radiogenic Pb and enriched Sr-Nd isotopic compositions of the host adakites. The high La, U and low Ti concentrations in the LYRB zircons also imply a volatile (perhaps, CO3 2--rich, carbonatite-like) source. Combined with whole-rock geochemical data, the new results further suggest contrasting origins of the LYRB and STLF adakites from subducted oceanic crust and foundering lower continental crust, respectively.The LYRB zircons have much higher ratios of Ce4+/Ce3+ (avg.417) and Eu/Eu* (avg. 0.67) than the STLF zircons (avg. 84 and 0.44). This difference confirms that the ore-bearing adakitic magmas are more oxidized relative to the ore-barren ones. There is roughly a positive correlation between zircon Ce4+/Ce3+ and δ18O in the LYRB series, probably indicating that the elevated fO2 was related to components enriched in heavy oxygen isotopes. A possible candidate is sediments, carried by subducting slabs. The involvement of sediments may significantly promote oxidation of the resulting adakitic melts, a key factor for generation of Cu-Au mineralization, e.g., in the LYRB. This study also indicates that combined in-situ analysis of zircon REEs and δ18O could be a powerful tool to decipher the intrinsic links of fO2 with sediment components in subduction zones. © 2012 Elsevier B.V.

Gao Q.,Hefei University of Technology | Gao Q.,City University of Hong Kong | Feng G.,City University of Hong Kong | Feng G.,Nanjing University of Science and Technology | And 2 more authors.
IEEE Transactions on Fuzzy Systems | Year: 2013

This paper investigates the universal fuzzy model and universal fuzzy controller problems for stochastic nonaffine nonlinear systems. The underlying mechanism of stochastic fuzzy logic is first discussed, and a stochastic generalized fuzzy model with new stochastic fuzzy rule base is then given. Based on their function approximation capability, these kinds of stochastic generalized fuzzy models are shown to be universal fuzzy models for stochastic nonaffine nonlinear systems under some sufficient conditions. An approach to stabilization controller design for stochastic nonaffine nonlinear systems is then developed through their stochastic generalized Takagi-Sugeno (T-S) fuzzy approximation models. Then, the results of universal fuzzy controllers for two classes of stochastic nonlinear systems, along with constructive procedures to obtain the universal fuzzy controllers, are also provided, respectively. Finally, a numerical example is presented to illustrate the effectiveness of the proposed approach. © 1993-2012 IEEE.

Xu H.-N.,Jiangnan University | Ma S.-F.,Jiangnan University | Chen W.,Hefei University of Technology
Soft Matter | Year: 2012

The effect of β-cyclodextrin (β-CD) on the aggregation behavior of a nonionic surfactant, Triton X-114 ((1,1,3,3-tetramethylbutyl)phenyl- polyethylene glycol), in aqueous solutions has been studied as a function of temperature by means of turbidity, dynamic light scattering (DLS), transmission electron microscopy (TEM), and rheo-small angle light scattering (rheo-SALS). The Triton X-114 (TX-114) solutions possess unique structural variations and display special aggregate transitions upon β-CD addition. In contrast to the reported aggregate disruption effect of β-CD for dilute nonionic surfactant solutions, aggregate growth is found in the aqueous TX-114 solutions of 93 mM upon β-CD addition. The micelle to vesicle transition induced by β-CD addition, which can greatly influence the turbidity and the viscosity of the solutions, is quantified by the characteristic length and aspect ratio of the aggregates. The characteristic length and aspect ratio of the aggregates change significantly after β-CD addition. It shows that aggregate growth may occur in nonionic surfactant-CD systems, as well as the reported ionic surfactant-CD systems. It is proposed that the CD-CD H-bonds create intermicelle interactions and promote aggregation of the CD/surfactant complexes, resulting in the formation of micrometer-scale phase-separated droplets. © 2012 The Royal Society of Chemistry.

Cong H.-P.,Hefei University of Technology | Cong H.-P.,Suzhou University of Science and Technology | Wang P.,Suzhou University of Science and Technology | Gong M.,Hefei University of Technology | Yu S.-H.,Suzhou University of Science and Technology
Nano Energy | Year: 2014

A new kind of nitrogen-doped graphene (NG) electrocatalyst with well-defined mesoporous structure has been for the first time fabricated by a scalable and templateless technique of directly annealing of pre-synthesized graphene oxide-polydopamine (GO/PDA) nanocomposites. Although with the high-temperature treatment, the obtained NG nanosheets in well-dispersed state are possessed with well-defined mesoporous architecture and large specific surface area owing to the pre-polymerization of dopamine on the GO nanosheets as the spacing. Furthermore, the prepared NG as the electrode material exhibits much more enhanced oxygen reduction reaction (ORR) activities with positive onset potential and large current density than the control samples. Moreover, compared with the commercial Pt/C, the optimized NG electrocatalyst displays better cycling stability and stronger tolerance to methanol crossover effect, making it a promising metal-free methanol-tolerant cathodic catalyst for practical fuel cells. © 2013 Elsevier Ltd.

Wang W.,Hefei University of Technology | Wang W.,Harbin Institute of Technology | Han H.,Harbin Institute of Technology
Bioresource Technology | Year: 2012

The impact of phenolic compounds (around 3.2g/L) resulted in a completely failed performance in a mesophilic UASB reactor treating coal gasification wastewater. The recovery strategies, including extension of HRT, dilution, oxygen-limited aeration, and addition of powdered activated carbon were evaluated in batch tests, in order to obtain the most appropriate way for the quick recovery of the failed reactor performance. Results indicated that addition of powdered activated carbon and oxygen-limited aeration were the best recovery strategies in the batch tests. In the UASB reactor, addition of powdered activated carbon of 1g/L shortened the recovery time from 25 to 9days and oxygen-limited aeration of 0-0.5mgO 2/L reduced the recovery time to 17days. Reduction of bioavailable concentration of phenolic compounds and recovery of sludge activity were the decisive factors for the recovery strategies to tackle the impact of phenolic compounds in anaerobic treatment of coal gasification wastewater. © 2011 Elsevier Ltd.

Yu H.-J.,Anhui Science and Technology University | Yu H.-J.,Chinese Academy of science | Yu H.-J.,Hefei University of Technology
Gene | Year: 2013

K-mer-based approach has been widely used in similarity analyses so as to discover similarity/dissimilarity among different biological sequences. In this study, we have improved the traditional K-mer method, and introduce a segmented K-mer approach (s-K-mer). After each primary sequence is divided into several segments, we simultaneously transform all these segments into corresponding K-mer-based vectors. In this approach, it is vital how to determine the optimal combination of distance metric with the number of K and the number of segments, i.e., (K*s*and d*. Based on the cascaded feature vectors transformed from s* segmented sequences, we analyze 34 mammalian genome sequences using the proposed s-K-mer approach. Meanwhile, we compare the results of s-K-mer with those of traditional K-mer. The contrastive analysis results demonstrate that s-K-mer approach outperforms the traditionally K-mer method on similarity analysis among different species. © 2012 Elsevier B.V.

Li J.,Anhui Science and Technology University | Chen W.,Hefei University of Technology
Nongye Jixie Xuebao/Transactions of the Chinese Society of Agricultural Machinery | Year: 2012

In order to obtain better robustness and real-time processing of path recognition, the binary segmentation image, noise searching and filtering procedures were employed. The whole path was classified into far part and near part, and the difference between the two parts was used as a threshold for selecting target road. So the navigating parameters were adapted to the changing path. Based on a model of four-wheel intelligent vehicle, a path tracking simulation was performed. Then, the navigation system based on path tracking was designed by using two digital signal processors. The experiments showed the accuracy and robustness of the system.

Huang X.,Hefei University of Technology | Huang X.,Tianjin Fire Research Institute | Wang X.S.,Hefei University of Technology | Liao G.X.,Hefei University of Technology
Proceedings of the Combustion Institute | Year: 2011

A gas-outside-liquid-inside water mist nozzle based on effervescent atomization technology is designed, characterized and tested in this paper. The droplets size distribution, velocity under different operation pressures and gas-liquid-ratios (GLR) are measured with a Phase Doppler Analyser (PDA). The gas flow rate, liquid flow rate of the nozzle with one or seven orifices are also characterized under different operation pressures and GLR conditions, respectively. The results show that all of above parameters are mainly influenced by GLR, i.e., the larger the GLR is, the smaller the droplet size will be, and the liquid mass flow rate is exponentially increased with the increasing of GLR. The test results of fire suppression show that this gas-outside-liquid-inside effervescent atomizer works well for fire extinguishment except the cases where the liquid flow rate is less than about 70 kg/h and the gas pressure is lower than 0.3 MPa. © 2010 The Combustion Institute. Published by Elsevier Inc. All rights reserved.

Gao H.-L.,Suzhou University of Science and Technology | Xu L.,Suzhou University of Science and Technology | Long F.,Hefei University of Technology | Pan Z.,Suzhou University of Science and Technology | And 4 more authors.
Angewandte Chemie - International Edition | Year: 2014

As macroscopic three dimensional (3D) architectures show increasing significance, much effort has been devoted to the hierarchical organization of 1D nanomaterials into serviceable macroscopic 3D assemblies. How to assemble 1D nanoscale building blocks into 3D hierarchical architectures is still a challenge. Herein we report a general strategy based on the use of ice as a template for assembling 1D nanostructures with high efficiency and good controllability. Free-standing macroscopic 3D Ag nanowire (AgNW) assemblies with hierarchical binary-network architectures are then fabricated from a 1D AgNW suspension for the first time. The microstructure of this 3D AgNW network endows it with electrical conductivity and allows it to be made into stretchable and foldable conductors with high electromechanical stability. These properties should make this kind of macroscopic 3D AgNW architecture and it composites suitable for electronic applications. Silver lining: Macroscopic free-standing hierarchical 3D architectures can be directly built from monodispersed silver nanowires (AgNW) through a general, versatile ice-template assembly technique without using any extra functionalization agents or crosslinking agents. The 3D nanowire monoliths have a binary-network microstructure which provides them with a high electrical conductivity, and, when impregnated with PDMS, great mechanical flexibility. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Feng Y.-S.,Hefei University of Technology | Xie C.-Q.,Hefei University of Technology | Qiao W.-L.,Hefei University of Technology | Xu H.-J.,Hefei University of Technology | Xu H.-J.,Key Laboratory of Advanced Functional Materials and Devices
Organic Letters | Year: 2013

An efficient Csp-CH2CF3 bond-forming reaction via Pd-catalyzed 2,2,2-trifluoroethylation of aryl and alkyl terminal alkynes has been developed. This protocol proceeds under mild conditions using the readily available and cheap reagent CF3CH2I as the source of the CH2CF3 group. Various terminal aryl alkynes as well as alkylacetylenes can be transformed into the corresponding trifluoroethylated products in good-to-excellent yields. The method is tolerant of carbonyl, nitro, ester, cyano, and even formyl groups. © 2013 American Chemical Society.

Mei Y.,Hefei University of Technology | Tang K.,Hefei University of Technology | Yao X.,Hefei University of Technology | Yao X.,University of Birmingham
IEEE Transactions on Evolutionary Computation | Year: 2011

The capacitated arc routing problem (CARP) is a challenging combinatorial optimization problem with many real-world applications, e.g., salting route optimization and fleet management. There have been many attempts at solving CARP using heuristic and meta-heuristic approaches, including evolutionary algorithms. However, almost all such attempts formulate CARP as a single-objective problem although it usually has more than one objective, especially considering its real-world applications. This paper studies multiobjective CARP (MO-CARP). A new memetic algorithm (MA) called decomposition-based MA with extended neighborhood search (D-MAENS) is proposed. The new algorithm combines the advanced features from both the MAENS approach for single-objective CARP and multiobjective evolutionary optimization. Our experimental studies have shown that such combination outperforms significantly an off-the-shelf multiobjective evolutionary algorithm, namely nondominated sorting genetic algorithm II, and the state-of-the-art multiobjective algorithm for MO-CARP (LMOGA). Our work has also shown that a specifically designed multiobjective algorithm by combining its single-objective version and multiobjective features may lead to competitive multiobjective algorithms for multiobjective combinatorial optimization problems. © 2006 IEEE.

Li S.,Hefei University of Technology | Dai C.,State Grid Corporation of China | Zhu Y.,Hefei University of Technology
International Journal of Electrical Power and Energy Systems | Year: 2012

Flexible power transmission are based on power electronic elements with series/parallel configuration and redundancy design. Because of the limited time span, fast replacement, and not fully reliable redundant elements due to unexposed failure, it is better to describe their reliability level with short-term evaluation instead of long-term evaluation. In short-term evaluation, the reliability of flexible transmission equipments is time-dependent, and decided by the initial state and the evaluation period, which is different from its steady-state value. In this paper, instantaneous state probability and unavailability for multi-state system within limited evaluation period are described analytically, and equivalenced with the average values. The algorithm is based on state transition matrix, and suitable for systems with different configurations. For systems with series or parallel elements, the steady-state and average unavailability are quantified, and compared with the existing method of multiplying the (un) availabilities each element directly. It is found that due to simultaneous failure and state transition, the existing method may yield error to the fixed and time-variant terms of the average unavailability. © 2012 Elsevier Ltd. All rights reserved.

Zhu H.,Hefei University of Technology | Xiong H.,Rutgers University | Ge Y.,UNC Charlotte | Chen E.,Hefei University of Technology
Proceedings of the ACM SIGKDD International Conference on Knowledge Discovery and Data Mining | Year: 2014

With the rapid prevalence of smart mobile devices, the number of mobile Apps available has exploded over the past few years. To facilitate the choice of mobile Apps, existing mobile App recommender systems typically recommend popular mobile Apps to mobile users. However, mobile Apps are highly varied and often poorly understood, particularly for their activities and functions related to privacy and security. Therefore, more and more mobile users are reluctant to adopt mobile Apps due to the risk of privacy invasion and other security concerns. To fill this crucial void, in this paper, we propose to develop a mobile App recommender system with privacy and security awareness. The design goal is to equip the recommender system with the functionality which allows to automatically detect and evaluate the security risk of mobile Apps. Then, the recommender system can provide App recommendations by considering both the Apps' popularity and the users' security preferences. Specifically, a mobile App can lead to security risk because insecure data access permissions have been implemented in this App. Therefore, we first develop the techniques to automatically detect the potential security risk for each mobile App by exploiting the requested permissions. Then, we propose a flexible approach based on modern portfolio theory for recommending Apps by striking a balance between the Apps' popularity and the users' security concerns, and build an App hash tree to efficiently recommend Apps. Finally, we evaluate our approach with extensive experiments on a large-scale data set collected from Google Play. The experimental results clearly validate the effectiveness of our approach. © 2014 ACM.

Lin M.,Hefei University of Technology | Tang K.,Hefei University of Technology | Yao X.,University of Birmingham
IEEE Transactions on Neural Networks and Learning Systems | Year: 2013

Class imbalance learning tackles supervised learning problems where some classes have significantly more examples than others. Most of the existing research focused only on binary-class cases. In this paper, we study multiclass imbalance problems and propose a dynamic sampling method (DyS) for multilayer perceptrons (MLP). In DyS, for each epoch of the training process, every example is fed to the current MLP and then the probability of it being selected for training the MLP is estimated. DyS dynamically selects informative data to train the MLP. In order to evaluate DyS and understand its strength and weakness, comprehensive experimental studies have been carried out. Results on 20 multiclass imbalanced data sets show that DyS can outperform the compared methods, including pre-sample methods, active learning methods, cost-sensitive methods, and boosting-type methods. © 2012 IEEE.

Li Y.,Harbin Institute of Technology | Wang S.,Hefei University of Technology | Zhao Y.,Harbin Institute of Technology | Ji Q.,Rensselaer Polytechnic Institute
IEEE Transactions on Image Processing | Year: 2013

The tracking and recognition of facial activities from images or videos have attracted great attention in computer vision field. Facial activities are characterized by three levels. First, in the bottom level, facial feature points around each facial component, i.e., eyebrow, mouth, etc., capture the detailed face shape information. Second, in the middle level, facial action units, defined in the facial action coding system, represent the contraction of a specific set of facial muscles, i.e., lid tightener, eyebrow raiser, etc. Finally, in the top level, six prototypical facial expressions represent the global facial muscle movement and are commonly used to describe the human emotion states. In contrast to the mainstream approaches, which usually only focus on one or two levels of facial activities, and track (or recognize) them separately, this paper introduces a unified probabilistic framework based on the dynamic Bayesian network to simultaneously and coherently represent the facial evolvement in different levels, their interactions and their observations. Advanced machine learning methods are introduced to learn the model based on both training data and subjective prior knowledge. Given the model and the measurements of facial motions, all three levels of facial activities are simultaneously recognized through a probabilistic inference. Extensive experiments are performed to illustrate the feasibility and effectiveness of the proposed model on all three level facial activities. © 1992-2012 IEEE.

News Article | February 15, 2017
Site: www.eurekalert.org

Li-S batteries are considered as promising alternatives for Li-ion batteries in the new generation of energy storages, due to high specific capacity (1675 mAh/g) and energy density (2600 mWh/g) of sulfur. But the poor conductivity of sulfur and severe shuttle effect of reaction intermediates destory the stability of this system. A variety of porous carbon materials have been applied as sulfur host to improve the performances of Li-S batteries for high conductivity, specific surface area and absorption effect. However, what kind of porous carbon would be the optimal choice to accommodate active material? And Which characteristic of carbon pores should be emphasized? A team of researchers from the School of Materials Science and Engineering and School of Electronic Science and Applied Physics at Hefei University of Technology demostrated that pore size distribution substantially influences the performances of cathode rather than specific surface area and total pore volume. Furthermore, an optimized assembly of micro/meso/macroporous carbon enables cathode present greatly improved electrochemical performances, in which micropore-volume-ratio to the total pore volume dominates cycling stability of batteries, meso/macropore-volume-ratio influences spaces for sulfur loading and channels to ion transfer. This research provides a direction of fabricating porous materials for energy storage.The report appears in the latest issue of the journal NANO. Based on the traditional S/C cathode, the effects of surface area, total pore volume and pore size distribution of carbon pores on performances of Li-S batteries are compared. In addition, on the premise of identically high sulfur content, the relation of the micro/meso/macropore volume ratio with the capacity, voltage plateau, rate capability, and cycle stability of Li-S battery are investigated. Among the samples, the porous carbon possesses the largest micropore volume ratio of 47.54% while a medium specific surface area of 1217 m2/g and inferior total pore volume of 0.54 cm3/g presents the highest initial discharge specific capacity of 1327 mAh/g and retention of 630 mAh/g over 100 cycles at 0.2C rate along with the best rate capability. The conclusions in this study can be directly applied in material fabrication for other systems of energy storage and even as criterions for further modification of Li-S batteries based on carbon material. This research was supported by the "Strategic Priority Research Program" of the Chinese Academy of Science (NO. XDA03040000) and the Fundamental Research Funds for the Central Universities (NO. 103-4115100010) of China. Additional co-authors of the NANO paper are Min Zuo, Jing Zhang, Yiqin Huang, Peiwen Bai, Jiaqi Xu, Kuan Zhou. Corresponding author for this study is Heqin Li, lhqjs@hfut.edu.cn. The paper can be found in the NANO journal.

Lin S.,University of Waterloo | Lin S.,Hefei University of Technology | Beakhouse G.P.,Geological Survey of Canada
Geology | Year: 2013

The Hemlo gold deposit (~700 t Au; northwestern Ontario, Canada) is hosted in a shear zone in the Hemlo greenstone belt, which is a synclinal keel between two granitoid domes. The dome-and-keel structure formed by diapirism and sagduction (vertical tectonism) that was synchronous with regional horizontal shearing (horizontal tectonism). Mineralization occurred during shearing, and mineralizing fluids probably had a magmatic source that is interpreted to be related to syntectonic mantle-derived granodiorite (sanukitoid) intrusions. The gold deposit, the intrusions, and the hosting shear zone all developed within a regime characterized by synchronous vertical and horizontal tectonism. They were all possibly linked to a range of processes associated with the accretionary growth and stabilization of the craton, in particular slab breakoff and the associated extensional orogenic collapse following terrane accretion. © 2013 Geological Society of America.

Leung K.C.-F.,Hong Kong Baptist University | Leung K.C.-F.,Chinese University of Hong Kong | Xuan S.,Chinese University of Hong Kong | Xuan S.,Hefei University of Technology | And 6 more authors.
Chemical Society Reviews | Year: 2012

This critical review provides an overview of current research activities that focused on the synthesis and application of multi-functional gold and iron oxide (Au-Fe xO y) hybrid nanoparticles and nanocomposites. An introduction of synthetic strategies that have been developed for generating Au-Fe xO y nanocomposites with different nanostructures is presented. Surface functionalisation and bioconjugation of these hybrid nanoparticles and nanocomposites are also reviewed. A variety of applications such as theranostics, gene delivery, biosensing, cell sorting, bio-separation, and catalysis is discussed and highlighted. Finally, future trends and perspectives of these sophisticated nanocomposites are outlined. Underpinning the fundamental requirements for effectively forming Au-Fe xO y hybrid nanocomposite materials would shed light on future development of nanotheranostics, nanomedicines, and chemical technologies. It would be interesting to investigate such multi-component composite nanomaterials with different novel morphologies in the near future to advance chemistry, biology, medicine, and engineering multi-disciplinary research (120 references). © 2012 The Royal Society of Chemistry.

Day J.M.D.,University of California at San Diego | Day J.M.D.,University of Maryland University College | Walker R.J.,University of Maryland University College | Qin L.,Carnegie Institution of Washington | And 2 more authors.
Nature Geoscience | Year: 2012

Core formation should strip highly siderophile elements (HSEs) from planetary mantles according to the expected metalg-silicate partition coefficients. However, studies of Earth, the Moon and Mars indicate mantles with HSE abundances in chondrite-relative proportions that exceed the values expected from metalg-silicate partitioning. Competing hypotheses have been proposed to account for these observations, including metalg-silicate partitioning at higher pressures and temperatures and late accretion. Here we present petrological and geochemical analyses of diogenite meteorites that represent mantle and crustal materials from two or more differentiated asteroids. We find that diogenites show HSE abundances that are consistent with metalg-silicate equilibration, followed by minor continued accretion. Isotope chronometry supports diogenite crystallization ages within 2-3 million years of Solar System formation, indicating that late accretion occurred earlier than postulated for Earth, the Moon and Mars. The early timing and occurrence on differentiated asteroids, as well as on the larger terrestrial planets, therefore ties late accretion to planetary growth. On asteroidal bodies, such as the diogenite parent bodies, variations in HSE compositions may reflect regional rather than global effects. In contrast, for Earth, the Moon and Mars, compositional variations in mantle materials seem to be consistent with more homogeneous distributions through prolonged melting and/or solid-state convection. © 2012 Macmillan Publishers Limited. All rights reserved.

Yang X.,Hefei University of Technology | Clausi D.A.,University of Waterloo
IEEE Journal of Selected Topics in Applied Earth Observations and Remote Sensing | Year: 2012

This paper presents a new approach to sea ice segmentation in synthetic aperture radar (SAR) intensity images by combining an edge-preserving region (EPR)-based representation with region-level MRF models. To construct the EPR-based representation of a SAR image, edge strength is measured using instantaneous coefficient of variation (ICOV) upon which the watershed algorithm is applied to partition the image into primitive regions. In addition, two new metrics for quantitative assessment of region characteristics (region accuracy and region redundancy) are defined and used for parameter estimation in the ICOV extraction process towards desired region characteristics. In combination with a region-level MRF, the EPR-based representation facilitates the segmentation process by largely reducing the search space of optimization process and improving parameter estimation of feature model, leading to considerable computational savings and less probability of false segmentation. The proposed segmentation method has been evaluated using a synthetic sea ice image corrupted with varying levels of speckle noise as well as real SAR sea ice images. Relative to the existing region-level MRF-based methods, testing results have demonstrated that our proposed method substantially improves the segmentation accuracy at high speckle noise and achieves on average 29% reduction of computational time. © 2008-2012 IEEE.

Ge T.,Hefei University of Technology | He K.,Microsoft | Ke Q.,Microsoft | Sun J.,Microsoft
IEEE Transactions on Pattern Analysis and Machine Intelligence | Year: 2014

Product quantization (PQ) is an effective vector quantization method. A product quantizer can generate an exponentially large codebook at very low memory/time cost. The essence of PQ is to decompose the high-dimensional vector space into the Cartesian product of subspaces and then quantize these subspaces separately. The optimal space decomposition is important for the PQ performance, but still remains an unaddressed issue. In this paper, we optimize PQ by minimizing quantization distortions w.r.t the space decomposition and the quantization codebooks. We present two novel solutions to this challenging optimization problem. The first solution iteratively solves two simpler sub-problems. The second solution is based on a Gaussian assumption and provides theoretical analysis of the optimality. We evaluate our optimized product quantizers in three applications: (i) compact encoding for exhaustive ranking , (ii) building inverted multi-indexing for non-exhaustive search , and (iii) compacting image representations for image retrieval. In all applications our optimized product quantizers outperform existing solutions. © 2014 IEEE.

Sheng J.,Hefei University of Technology | Ding Z.,University of Manchester
IET Control Theory and Applications | Year: 2013

This study investigates the consensus control of linear multi-agent systems with communication time delay. Upon exploring certain features of Laplacian matrix, optimal consensus control conditions are identified using semi-discretisation method that develops a mapping of the system response in a finite-dimensional state space. Consensus region and consensus boundary can be obtained by comparing the maximum absolute value of the mapping's eigenvalues with 1. Besides, minimisation of the maximum absolute value of the eigenvalues leads to optimal control gains representing fastest convergence speed. The proposed control only uses relative state information of the system. Numerical simulations validate the proposed control design and show the performance with different control gains and time delays. © The Institution of Engineering and Technology 2013.

Xiang G.Y.,Griffith University | Xiang G.Y.,Hefei University of Technology | Higgins B.L.,Griffith University | Berry D.W.,University of Waterloo | And 2 more authors.
Nature Photonics | Year: 2011

Precise interferometric measurement is vital to many scientific and technological applications. Using quantum entanglement allows interferometric sensitivity that surpasses the shot-noise limit (SNL). To date, experiments demonstrating entanglement-enhanced sub-SNL interferometry, and most theoretical treatments, have addressed the goal of increasing signal-to-noise ratios. This is suitable for phase-sensing - detecting small variations about an already known phase. However, it is not sufficient for ab initio phase-estimation - making a self-contained determination of a phase that is initially completely unknown within the interval [0, 2π). Both tasks are important, but not equivalent. To move from the sensing regime to the ab initio estimation regime requires a non-trivial phase-estimation algorithm. Here, we implement a 'bottom-up' approach, optimally utilizing the available entangled photon states, obtained by post-selection. This enables us to demonstrate sub-SNL ab initio estimation of an unknown phase by entanglement-enhanced optical interferometry. © 2011 Macmillan Publishers Limited. All rights reserved.

Xiong J.,Hefei University of Technology | Petersen I.R.,Australian Defence Force Academy | Lanzon A.,University of Manchester
Automatica | Year: 2012

The paper is concerned with the notion of lossless negative imaginary systems and their stabilization using strictly negative imaginary controllers through positive feedback. Firstly, the concept of lossless negative imaginary transfer functions is introduced and some properties of such transfer functions are studied. Secondly, a Lossless Negative Imaginary Lemma is given which establishes conditions on matrices appearing in a minimal state-space realization that are necessary and sufficient for a transfer function to be lossless negative imaginary. Thirdly, a necessary and sufficient condition is provided for the stabilization of a lossless negative imaginary system by a strictly negative imaginary controller. Finally, a flexible structure example is presented to illustrate the theory. © 2012 Elsevier Ltd. All rights reserved.

Gong X.,CAS Suzhou Institute of Nano Technology and Nano Bionics | Li J.,Hefei University of Technology | Xu K.,CAS Suzhou Institute of Nano Technology and Nano Bionics | Wang J.,CAS Suzhou Institute of Nano Technology and Nano Bionics | And 2 more authors.
Journal of the American Chemical Society | Year: 2010

The selective rate of specific ion transport across nanoporous material is critical to biological and nanofluidic systems. Molecular sieves for ions can be achieved by steric and electrical effects. However, the radii of Na+ and K+ are quite similar; they both carry a positive charge, making them difficult to separate. Biological ionic channels contain precisely arranged arrays of amino acids that can efficiently recognize and guide the passage of K+ or Na+ across the cell membrane. However, the design of inorganic channels with novel recognition mechanisms that control the ionic selectivity remains a challenge. We present here a design for a controllable ion-selective nanopore (molecular sieve) based on a single-walled carbon nanotube with specially arranged carbonyl oxygen atoms modified inside the nanopore, which was inspired by the structure of potassium channels in membrane spanning proteins (e.g., KcsA). Our molecular dynamics simulations show that the remarkable selectivity is attributed to the hydration structure of Na + or K+ confined in the nanochannels, which can be precisely tuned by different patterns of the carbonyl oxygen atoms. The results also suggest that a confined environment plays a dominant role in the selectivity process. These studies provide a better understanding of the mechanism of ionic selectivity in the KcsA channel and possible technical applications in nanotechnology and biotechnology, including serving as a laboratory-in-nanotube for special chemical interactions and as a high-efficiency nanodevice for purification or desalination of sea and brackish water. © 2010 American Chemical Society.

Xiong Z.,Hefei University of Technology | Sun X.,Microsoft | Wu F.,Microsoft
IEEE Transactions on Image Processing | Year: 2010

This paper proposes a robust single-image super-resolution method for enlarging low quality web image/video degraded by downsampling and compression. To simultaneously improve the resolution and perceptual quality of such web image/video, we bring forward a practical solution which combines adaptive regularization and learning-based super-resolution. The contribution of this work is twofold. First, we propose to analyze the image energy change characteristics during the iterative regularization process, i.e., the energy change ratio between primitive (e.g., edges, ridges and corners) and nonprimitive fields. Based on the revealed convergence property of the energy change ratio, appropriate regularization strength can then be determined to well balance compression artifacts removal and primitive components preservation. Second, we verify that this adaptive regularization can steadily and greatly improve the pair matching accuracy in learning-based super-resolution. Consequently, their combination effectively eliminates the quantization noise and meanwhile faithfully compensates the missing high-frequency details, yielding robust super-resolution performance in the compression scenario. Experimental results demonstrate that our solution produces visually pleasing enlargements for various web images/videos. © 2006 IEEE.

Xiong Z.,Hefei University of Technology | Sun X.,Microsoft | Wu F.,Microsoft
IEEE Transactions on Image Processing | Year: 2010

This correspondence presents an image compression approach that integrates our proposed parameter-assistant inpainting (PAI) to exploit visual redundancy in color images. In this scheme, we study different distributions of image regions and represent them with a model class. Based on that, an input image at the encoder side is divided into featured and non-featured regions at block level. The featured blocks fitting the predefined model class are coded by a few parameters, whereas the non-featured blocks are coded traditionally. At the decoder side, the featured regions are restored through PAI relying on both delivered parameters and surrounding information. Experimental results show that our method outperforms JPEG in featured regions by an average bit-rate saving of 76% at similar perceptual quality levels. © 2010 IEEE.

Wang S.,University of Manchester | Pei B.,Hefei University of Technology | Zhao X.,University of Texas at Austin | Dryfe R.A.W.,University of Manchester
Nano Energy | Year: 2013

We successfully prepared a highly porous graphene on carbon cloth (PG/CC) via an electrophoretic deposition process. With this process, in order to obtain high porous graphene on carbon cloth, fine-size graphene should be used. When large-size graphene was used, carbon cloth was only covered by graphene (G/CC) without porous surface. PG/CC was used as electrodes for Flexible All-Solid-State Supercapacitors (FASSSs). The porous structure of PG/CC electrode significantly increased the surface area of graphene and thus the specific capacitance (79.19Fg-1 for PG/CC and 32.35Fg-1 for G/CC). The macroscopic porous morphology of carbon cloth as the electrode matrix enhanced the integration between electrode and electrolyte, which is favorable for the ion diffusion and electron transport. The excellent mechanical stability and flexibility of PG/CC ensures the device with good flexibility. The resultant PG/CC based FASSSs showed high specific capacitance, good cycling stability, and enhanced energy density and power density. © 2013 Elsevier Ltd.

Zhang K.Z.K.,Hefei University of Technology | Cheung C.M.K.,Hong Kong Baptist University | Lee M.K.O.,City University of Hong Kong
International Journal of Information Management | Year: 2014

The prevalence of social media has provided consumers with many opportunities to post online reviews on a wide range of products on the Internet. In this study, we attempt to investigate the moderating effect of inconsistent reviews (i.e., a mix of positive and negative reviews) on consumers' purchase decision. We further examine whether the effect will differ from female to male consumers. We explain the moderating effect and its gender differences based on the theory of reasoned action, trust literature, and information processing literature. The research hypotheses are empirically tested in a laboratory experiment using structural equation modeling approach. Our findings show that consumers' cognitive trust to online retailers affects emotional trust, which further leads to purchase intention. When consumers are exposed to inconsistent reviews, the influence of emotional trust on purchase intention is significantly stronger. Moreover, the moderating effect of inconsistent reviews is stronger for female consumers than for male consumers. We expect that this study can enrich the understanding of how inconsistent reviews play a role in consumers' online shopping decision. Online retailers may apply our findings and leverage the influence of online consumer reviews in social media. Implications for both researchers and practitioners are discussed. © 2013 Elsevier Ltd.

Wu S.,Hefei University of Technology | Tan W.,Hefei University of Technology | Xu H.,Hefei Third Peoples Hospital
Analyst | Year: 2010

A hemoglobin sensor based on a molecularly imprinted polymer-modified electrode has been fabricated by electrochemically induced redox polymerization of acrylamide in the presence of hemoglobin. © The Royal Society of Chemistry 2010.

Zhang Y.,Hefei University of Technology | Xiong Z.,Microsoft | Wu F.,Microsoft
Applied Optics | Year: 2013

This paper proposes a novel phase-shifting method for fast, accurate, and unambiguous 3D shape measurement. The basic idea is embedding a speckle-like signal in three sinusoidal fringe patterns to eliminate the phase ambiguity, but without reducing the fringe amplitude or frequency. The absolute depth is then recovered through a robust region-wise voting strategy relying on the embedded signal. Using the theoretical minimum of only three images, the proposed method greatly facilitates the application of phase shifting in time-critical conditions. Moreover, the proposed method is resistant to the global illumination effects, as the fringe patterns used are with a single high frequency. Based on the proposed method, we further demonstrate a real-time, high-precision 3D scanning system with an off-the-shelf projector and a commodity camera. © 2013 Optical Society of America.

Xiong J.,Hefei University of Technology | Petersen I.R.,Australian Defence Force Academy | Lanzon A.,University of Manchester
IEEE Transactions on Automatic Control | Year: 2010

The note is concerned with linear negative imaginary systems. First, a previously established Negative Imaginary Lemma is shown to remain true even if the system transfer function matrix has poles on the imaginary axis. This result is achieved by suitably extending the definition of negative imaginary transfer function matrices. Secondly, a necessary and sufficient condition is established for the internal stability of the positive feedback interconnections of negative imaginary systems. Meanwhile, some properties of linear negative imaginary systems are developed. Finally, an undamped flexible structure example is presented to illustrate the theory. © 2010 IEEE.

Xiong J.,Hefei University of Technology | Petersen I.R.,Australian Defence Force Academy | Lanzon A.,University of Manchester
IEEE Transactions on Automatic Control | Year: 2012

This technical note is concerned with finite frequency negative imaginary (FFNI) systems. Firstly, the concept of FFNI transfer function matrices is introduced, and the relationship between the FFNI property and the finite frequency positive real property of transfer function matrices is studied. Then the technical note establishes an FFNI lemma which gives a necessary and sufficient condition on matrices appearing in a minimal state-space realization for a transfer function to be FFNI. Also, a time-domain interpretation of the FFNI property is provided in terms of the system input, output and state. Finally, an example is presented to illustrate the FFNI concept and the FFNI lemma. © 2012 IEEE.

Hu H.,Hefei University of Technology | Hu H.,Chinese Academy of Sciences | Wu J.,Bell Laboratories
IEEE Transactions on Information Theory | Year: 2014

An (N, K) codebook C is a set of N unit-norm complex vectors in ℂk. Optimal codebooks meeting the Welch bound with equality are desirable in a number of areas. However, it is very difficult to construct such optimal codebooks. There have been a number of attempts to construct codebooks nearly meeting the Welch bound with equality, i.e., the maximal cross-correlation amplitude Imax (C) is slightly higher than the Welch bound equality, but asymptotically achieves it for large enough N. In this paper, using difference sets and the product of Abelian groups, we propose new constructions of codebooks nearly meeting the Welch bound with equality. Our methods yield many codebooks with new parameters. In some cases, our constructions are comparable to known constructions. © 1963-2012 IEEE.

Liu S.A.,Hefei University of Technology | Li S.,Hefei University of Technology | He Y.,Hefei University of Technology | Huang F.,ETH Zurich
Geochimica et Cosmochimica Acta | Year: 2010

Adakites are commonly associated with porphyry Cu-Au ore deposits worldwide. Two groups of early Cretaceous adakites occur widely in central-eastern China but their association with mineralization contrasts sharply: adakites from the Lower Yangtze River Belt (LYRB) host one of the largest porphyry Cu-Au deposit belts in China, whereas those from the South Tan-Lu Fault (STLF), which is adjacent to the LYRB, are all ore-barren. These adakites, thus, provide a rare opportunity to explore the main factor that controls the genetic links between adakites and Cu-Au mineralization. Here we report new chronological, elemental and Sr-Nd-Pb isotopic data and present a comprehensive geochemical comparison for these two groups of adakites. At a given SiO2, the STLF adakites show lower Al2O3 and higher K2O, K2O/Na2O, MgO, Cr, Ni and Mg# than the LYRB adakites. These systematic differences may indicate a dry basaltic source for the STLF adakites and a water-enriched basaltic source for the LYRB adakites. The STLF adakites have high Sr/Y and (La/Yb)N, which are positively correlated, and low Sr/La and Ce/Pb, while the LYRB adakites show lower (La/Yb)N but higher Sr/Y, Sr/La and Ce/Pb than the STLF adakites. Furthermore, the LYRB adakites are characterized by highly radiogenic Pb isotopic compositions with 206Pb/204Pb(t) up to 18.8, which are clearly distinct from the STLF adakites with low radiogenic Pb (206Pb/204Pb(t)=15.8-16.4). Although the high Mg# of the two groups of adakites suggest reaction with mantle peridotites during magma ascent, the geochemical comparisons indicate that the STLF adakites were derived from partial melting of the delaminated eclogitic lower continental crust, while the LYRB adakites were derived from partial melting of the seawater-altered oceanic crust that was being subducted towards the LYRB during the early Cretaceous. The petrogenetic contrasts between these two groups of high-Mg adakites, therefore, indicate that the large-scale Cu-Au mineralization is associated with oceanic slab melting, not delamination or recycling of the ancient lower continental crust, as previously proposed. © 2010 Elsevier Ltd.

Zhou W.,Hefei University of Technology | Li H.,Hefei University of Technology | Lu Y.,Texas State University | Tian Q.,University of Texas at San Antonio
IEEE Transactions on Image Processing | Year: 2012

License plates detection is widely considered a solved problem, with many systems already in operation. However, the existing algorithms or systems work well only under some controlled conditions. There are still many challenges for license plate detection in an open environment, such as various observation angles, background clutter, scale changes, multiple plates, uneven illumination, and so on. In this paper, we propose a novel scheme to automatically locate license plates by principal visual word (PVW), discovery and local feature matching. Observing that characters in different license plates are duplicates of each other, we bring in the idea of using the bag-of-words (BoW) model popularly applied in partial-duplicate image search. Unlike the classic BoW model, for each plate character, we automatically discover the PVW characterized with geometric context. Given a new image, the license plates are extracted by matching local features with PVW. Besides license plate detection, our approach can also be extended to the detection of logos and trademarks. Due to the invariance virtue of scale-invariant feature transform feature, our method can adaptively deal with various changes in the license plates, such as rotation, scaling, illumination, etc. Promising results of the proposed approach are demonstrated with an experimental study in license plate detection. © 1992-2012 IEEE.

Fang M.-J.,Shanghai Normal University | Wang J.-F.,Hefei University of Technology | Li G.-Q.,Tongji University
Journal of Constructional Steel Research | Year: 2013

A shaking table test of a steel frame with autoclaved lightweight concrete (ALC) external wall panels is described in this paper. The specimen is a two-story full-scale model filled with external vertical wall panels, external horizontal wall panels and internal vertical wall panels. The input wave of the shaking table was generated by the El-Centro 1940 earthquake spectrum. Based on the experimental results, the seismic behavior of ALC external walls and joints was analyzed, such as the failure modes of ALC external walls and joints and the effects of external walls on the dynamic response of steel frame. The test results show that there is no great crack or damage on the wall panels at the tenth seismic intensity because of the enough intensity. The comparison between the steel frame models with and without wall panels indicates that the contribution of external wall panels to the steel frame stiffness can reach up to 25% and the damping ratio can exceed 7%. The analysis results also show that the joints are stable enough to resist the seismic loads and can provide enough flexible deformation so that the wall panels can stand large structure deformation. The screws on band iron of openings are very easy to loosen. Therefore, the joints between the band iron and wall panels should be reinforced. © 2012 Elsevier Ltd. All rights reserved.

Bai X.-X.,Hefei University of Technology | Wereley N.M.,University of Maryland University College
Journal of Applied Physics | Year: 2014

Magnetorheological (MR) energy absorbers (EAs) are an effective adaptive EA technology with which to maximize shock and vibration isolation. However, to realize maximum performance of the semi-active control system, the off-state (i.e., field off) stroking load of the MREA must be minimized at all speeds, and the dynamic range of the MREA must be maximized at high speed. This study presents a fail-safe MREA (MREA-FS) concept that, can produce a greater dynamic range at all piston speeds. A bias damping force is generated in the MREA-FS using permanent magnetic fields, which enables fail-safe behavior in the case of power failure. To investigate the feasibility and capability of the MREA-FS in the context of the semi-active control systems, a single-degree-of-freedom base excited rigid payload is mathematically constructed and simulated with skyhook control. © 2014 AIP Publishing LLC.

Ma J.,Southwest Jiaotong University | Lo S.M.,City University of Hong Kong | Song W.G.,Hefei University of Technology
Fire Safety Journal | Year: 2012

With the development of modern cities, numerous buildings over 40-storey have been constructed in recent decades. Fire safety issues, especially evacuation, are of the major concerns for building designers, occupants, as well as governments. To ensure the safety of ultra high-rise building evacuation, different performance-based designs have been proposed. In this study, we propose a quantitative and viable elevator aided ultra-high rise building evacuation model which simulates both pedestrian movement and elevator transportation. After validation and calibration, the proposed Ultra high-rise building Evacuation with Elevators (UEE) model is adopted to explore two main evacuation strategies, i.e., phased evacuation and total evacuation with the aid of elevators. In these two strategies, refuge floor plays an important part because it not only provides a place for temporarily stop, but also for the transition from stair evacuation into elevator evacuation. Thus, the effect of refuge floor interval on the high-rise building evacuation process is further investigated. It is found that the interval design of refuge floors has a direct relation with the characteristics of the elevators and building occupants. In the case that a proper ratio of the building occupants is transported to the ground level by fast elevators while others are evacuated by stairs, the evacuation process can reach an optimized state. © 2012 Elsevier Ltd.

Ma J.,Southwest Jiaotong University | Song W.,Hefei University of Technology
Procedia Engineering | Year: 2013

To ensure the safety of pedestrians in crowds under emergency situation is one of the most important concerns of researchers of building safety, traffic facility design as well as pedestrian traffic planning. Simulations as a consequence have been extensively studied to locate potential locations where danger might happen. However when abnormal pedestrian flow pattern occurs, control or guidance methods should be provided to other pedestrians based on the real-time information about the flow pattern. Thus in the present paper an automatically clustering method for detecting abnormal flow pattern is proposed. The method takes into account the interrelation between individual behavior and global pedestrian flow pattern. As a result it is indicated by the experimental and testing videos that the method is robust and efficient. © 2013 International Association for Fire Safety Science.

Liu B.,Maurice Morton Institute of Polymer Science | Liu B.,Hefei University of Technology | Wang J.,Maurice Morton Institute of Polymer Science | Zhang G.,University of Akron | And 2 more authors.
ACS Applied Materials and Interfaces | Year: 2014

We have designed and synthesized a novel ratiometric fluorescent chemodosimeter MHF-based ESIPT process for specific detection of cysteine among the biological thiols. The probe MHF shows very weak blue fluorescence under UV excitation. Upon addition of cysteine (Cys), the reaction of Cys with MHF induces acrylate hydrolysis, thereby enabling the ESIPT process to shift the weak blue emission to a strong green emission with about 20-fold enhancement. We utilized 1H NMR spectra to elucidate the fluorescence sensing mechanism. Moreover, the cellular imaging experiment indicated the MHF possessed excellent selectivity, low cytotoxicity, and desirable cell permeability for biological applications. © 2014 American Chemical Society.

Xie S.,National University of Ireland | Lawlor P.G.,Teagasc | Frost J.P.,Hillsborough Co. Down | Hu Z.,Hefei University of Technology | Zhan X.,National University of Ireland
Bioresource Technology | Year: 2011

Anaerobic co-digestion of concentrated pig manure (PM) with grass silage (GS) at five different PM to GS volatile solid (VS) ratios of 1:0, 3:1, 1:1, 1:3 and 0:1 was evaluated by examining operation stability and methane (CH4) production potentials. The highest specific CH4 yields were 304.2 and 302.8ml CH4/g VS at PM to GS ratios of 3:1 and 1:1, respectively. The digestion systems failed at the ratio of 0:1. The lag phase lasted 29.5, 28.1, 24.6 and 21.3days at the ratios of 1:0, 3:1, 1:1 and 1:3, respectively. The daily methane yield was linearly correlated with the acetic acid concentration, indicating methane production was probably associated with acetoclastic methanogenesis. The hydrolysis constant linearly decreased with increasing the fraction of GS in the feedstock. This study recommends applying the PM to GS ratio of 1:1 in practice due to a high specific methane yield and a short lag phase. © 2011 Elsevier Ltd.

Fang S.,Hefei University of Technology | Fang S.,State University of New York at Buffalo | Xia X.S.,Hefei University of Technology | Xing H.,Hefei University of Technology | Chen C.W.,State University of New York at Buffalo
Optics Express | Year: 2014

The analysis of polarized filtered images has been proven useful in image dehazing. However, the current polarization-based dehazing algorithms are based on the assumption that the polarization is only associated with the airlight. This assumption does not hold up well in practice since both object radiance and airlight contribute to the polarization. In this study, a new polarization hazy imaging model is presented, which considers the joint polarization effects of the airlight and the object radiance in the imaging process. In addition, an effective method to synthesize the optimal polarized-difference (PD) image is introduced. Then, a decorrelation-based scheme is proposed to estimate the degree of polarization for the object from the polarized image input. After that, the haze-free image can be recovered based on the new polarization hazy imaging model. The qualitative and quantitative experimental results verify the effectiveness of this new dehazing scheme. As a by-product, this scheme also provides additional polarization properties of the objects in the image, which can be used in extended applications, such as scene segmentation and object recognition. © 2014 Optical Society of America.

Yang X.-Y.,Hefei University of Technology | Yang X.-Y.,Chinese Academy of science | Lee I.,Seoul National University
International Geology Review | Year: 2011

Ore deposition took place in the Yangtze Valley episodically during the Jurassic and Cretaceous periods, generating approximately 200 polymetallic Cu-Fe-Au, Mo, Zn, Pb, and Ag deposits. We analysed the stable isotopes of sulphur, oxygen, and hydrogen from the Cu-Au deposits and correlated our new data with published stable isotope for associated Yanshanian (Mesozoic) igneous rocks. The latter bears a close relationship to Cu-Au mineralization in the area. Cu-Au deposits in the middle-lower Yangtze Valley can be divided into three types: skarn, porphyry, and volcanic. The S-O-H isotopic values allow constraints to be placed on the conditions of origin of these famous Cu-Au ores and their related igneous rocks. Sulphur from the sulphide ores mostly was derived from a magmatic source; however, a few deposits reflect a sedimentary source of sulphur. Oxygen isotope values in quartz from the Shaxi porphyry Cu-Au deposit and from the Tongling skarn Cu-Au deposits range from 2.6 to 12.5 and from-1.3 to 24.5, respectively; these values represent larger variations compared with those from other Cu-Au deposits in this metallogenic belt. Hydrogen versus oxygen isotope plots of the Cu-Au ore-forming fluids demonstrate that the fluids came from different sources: the most important involved the mixing of magmatic and meteoric water; the second most important was strictly magmatic water; and the third most important may have been a mixture of formation water or meteoric water that had reacted with carbonate wall rocks. © 2011 Taylor & Francis.

Xie J.,Hefei University of Technology | Yang X.,Hefei University of Technology | Sun W.,CAS Guangzhou Institute of Geochemistry | Du J.,Anhui Academy of Geological Survey
Lithos | Year: 2012

The Tongling district in the Lower Yangtze River belt is one of the most important Cu-polymetal producers in China. Copper-Au deposits in the region are closely related to Early Cretaceous dioritic intrusions, which can be classified into three rock associations: pyroxene diorite-pyroxene monzodiorite, quartz diorite-quartz monzodiorite and granodiorite. The dioritic rock series (SiO 2=54.6-64.5wt.%) are calc-alkaline, with high Al 2O 3 (>15.4wt.%), Ba (Ba>700ppm) and Sr concentrations (~920ppm in average), and low Y and Yb concentrations, all of which are typical for adakite. Geochemical characteristics suggest that the Tongling adakitic rocks are genetically related to slab melting and subsequent interaction with the mantle, likely during a ridge subduction along the Lower Yangtze River Belt in the Early Cretaceous. Geothermometers show high formation temperatures of 800-900°C, which is consistent with interaction with the asthenosphere mantle as indicated. The relatively low ε Nd(t) values (-11.2 to -16.7) and high ( 87Sr/ 86Sr) i ratios (0.7067 to 0.7095) may be plausibly interpreted by contamination of enriched mantle materials and/or continental crust. The Tongling dioritic rocks are characterized by high radiogenic Pb isotopes with ( 206Pb/ 204Pb) i=17.80-18.56, ( 207Pb/ 204Pb) i=15.46-15.60, and ( 208Pb/ 204Pb) i=37.92-38.48, which mostly plot in the field of MORB, near the intersection of EM-1 and EM-2, and are clearly different from those of the upper and lower continental crust and Dabie adakites. These exclude major contamination from the continental crust. Given that eastern China has both EM-1 and EM-2 types of enriched mantle, whereas the Tongling region is located near the transition from EM-1 to EM-2, the enriched Sr-Nd isotopic characteristics of Tongling adakites are best explained by slab melts with assimilation of enriched mantle components. © 2012.

Li B.,Xi'an Jiaotong University | Hong J.,Xi'an Jiaotong University | Liu Z.,Hefei University of Technology
International Journal of Machine Tools and Manufacture | Year: 2014

This paper introduces a novel approach for designing the stiffener layout inside large machine tools by applying the self-optimal growth principle of plant ramifications in nature. Firstly, numerical studies are carried out in order to confirm the potential of leaf venation as concept generators for creating the optimal load-bearing topology for stiffened machine tool structures. Then, a mathematical model explaining the optimality of plant morphogenesis is presented. Based on this, an evolutionary algorithm is developed, which uses three growth strategies to determine the candidate stiffeners to grow or atrophy with respect to the loads applied. The proposed growth-based method could generate a distinct stiffener layout, which is different to those produced by the conventional topology optimization methods, and thus offers unique possibilities of improving the design efficiency and commonality for machine tool development. The suggested approach is finally applied to the re-design of an actual grinding machine column, on which the numerical analyses and experimental tests conducted exemplify the performance enhancement, and therefore is a good choice for the stiffener layout design of machine tool structures. © 2014 Elsevier Ltd.

Wang J.-Z.,Hefei University of Technology | Li H.-Z.,CAS Guangzhou Institute of Geochemistry | Li H.-Z.,University of Chinese Academy of Sciences | You J.,CAS Guangzhou Institute of Geochemistry
Environmental Pollution | Year: 2012

Current-use insecticides including organophosphate (OPs) and synthetic pyrethroid (SPs) insecticides were analyzed in 35 sediment samples collected from Chaohu Lake in China, where a transition from a traditional agricultural to a modern urbanized society is ongoing. Total concentrations of five OPs and eight SPs ranged from 0.029 to 0.681 ng/g dry weight and 0.016-301 ng/g dry weight, respectively. Toxic unit analysis showed that 13% of the sediment samples likely produced over 50% of the mortality for benthic invertebrates. Analysis also showed that cypermethrin was the principal contributor to the toxicity. Spatial distribution evaluation implied that OPs were mainly from non-point sources associated with agricultural activities. Conversely, SPs may have been derived from runoff of inflowing rivers through urban regions, as their concentrations were well-correlated with concentrations of other urban-oriented contaminants. © 2011 Elsevier Ltd. All rights reserved.

Gao X.-Y.,Hefei University of Technology | Zheng Y.-F.,Hefei University of Technology | Chen Y.-X.,Hefei University of Technology | Hu Z.,Wuhan University
Journal of Metamorphic Geology | Year: 2013

The ultrahigh-pressure (UHP) eclogite in the Dabie orogen preserves petrological evidence for the existence of hydrous silicate melts that formed during continental subduction-zone metamorphism. This is indicated by occurrence of multiphase solid (MS) inclusions in garnet that primarily consist of K-feldspar + quartz ± epidote/allanite. All the MS inclusions are euhedral to subhedral in morphology and surrounded with radial cracks in the host garnet. Their trace element compositions were analysed by two different approaches of laser sampling. The mass budget method was used to estimate the trace element abundances of MS inclusions from their mixtures with the host garnet. The results are compared with the direct sampling of MS inclusions, providing a first-order approximation to the trace element composition of MS inclusions. The MS inclusions exhibit consistent enrichment of LILE, Sr and Pb, but depletion of HFSE in the primitive mantle-normalized spidergram. Such arc-like patterns of trace element distribution are common for continental crustal rocks. The melts have variably high K, Rb and Sr abundances, suggesting that breakdown of phengite is a basic cause for partial melting of the UHP eclogite. These MS inclusions also exhibit consistently low HFSE and Y contents, suggesting partial melting of the eclogite in the stability fields of rutile and garnet. Consequently, the trace element composition of MS inclusions provides a proxy for that of hydrous silicate melts derived from dehydration melting of the UHP eclogite during continental collision. © 2012 Blackwell Publishing Ltd.

Sheng Y.-M.,Hefei University of Technology | Zheng Y.-F.,Hefei University of Technology | Li S.-N.,Hefei University of Technology | Hu Z.,Wuhan University
Journal of Metamorphic Geology | Year: 2013

Metamorphic dehydration and partial melting are two important processes during continental collision. They have significant bearing on element transport at the slab interface under subduction-zone P-T conditions. Petrological and geochemical insights into the two processes are provided by a comprehensive study of leucocratic veins in ultrahigh-pressure (UHP) metamorphic rocks. This is exemplified by this study of a polymineralic vein within phengite-bearing UHP eclogite in the Dabie orogen. The vein is primarily composed of quartz, kyanite, epidote and phengite, with minor accessory minerals such as garnet, rutile and zircon. Primary multiphase solid inclusions occur in garnet and epidote from the both vein and host eclogite. They are composed of quartz±K-feldspar±plagioclase±K-bearing glass and exhibit irregular to negative crystal shapes that are surrounded by weak radial cracks. This suggests their precipitation from solute-rich metamorphic fluid/melt that involved the reaction of phengite breakdown. Zircon U-Pb dating for the vein gave two groups of concordant ages at 217±2 and 210±2Ma, indicating two episodes of zircon growth in the Late Triassic. The same minerals from the two rocks give consistent δ18O and δD values, suggesting that the vein-forming fluid was directly derived from the host UHP eclogite. The vein is much richer in phengite and epidote than the host eclogite, suggesting that the fluid is associated with remarkable concentration of such water-soluble elements as LILE and LREE migration. Garnet and rutile in the vein exhibit much higher contents of HREE (2.2-5.7 times) and Nb-Ta (1.8-2.0 times) than those in the eclogite, indicating that these normally water-insoluble elements became mobile and then were sunken in the vein minerals. Thus, the vein-forming agent would be primarily composed of the UHP aqueous fluid with minor amounts of the hydrous melt, which may even become a supercritical fluid to have a capacity to transport not only LILE and LREE but also HREE and HFSE at subduction-zone metamorphic conditions. Taken together, significant amounts of trace elements were transported by the vein-forming fluid due to the phengite breakdown inside the UHP eclogite during exhumation of the deeply subducted continental crust. © 2012 Blackwell Publishing Ltd.

Chen Y.-X.,Hefei University of Technology | Zheng Y.-F.,Hefei University of Technology | Hu Z.,Wuhan University
Lithos | Year: 2013

Petrological evidence is provided for partial melting of ultrahigh-pressure (UHP) metamorphic granitic gneiss in the Sulu orogen. Petrographic observations show the occurrence of elongated, highly cuspate feldspars in grain boundaries, interstitial cuspate feldspars in triple junctions, felsic veinlets mainly consisting of K-feldspar. +. quartz, and feldspar crystal faces against quartz. These features indicate that the feldspar and quartz would have grown from anatectic melts in the granitic gneiss. Zircon domains grown from these melts were identified based on CL images, mineral inclusions and REE patterns. Some large zircon grains (>. 100μm) contain small relict domains of magmatic origin, suggesting nearly complete dissolution of the protolith zircon during the anatexis. All newly grown zircon domains are categorized into two groups based on the presence or absence of coesite inclusions. One group of domains contain no coesite inclusion and exhibit high U contents but low Th/U ratios (<. 0.1), steep REE patterns with strong negative Eu anomalies, and U. Pb ages of 217. ±. 2 to 224. ±. 2. Ma. The other group of domains contain coesite inclusions and exhibit low U contents and very low Th/U ratios (<. 0.01), steep REE patterns with strong negative Eu anomalies, and U. Pb ages of 221. ±. 5 to 226. ±. 3. Ma. The two groups of zircon domains are thus interpreted as growing from the anatectic melts at different pressures because they exhibit marked negative Eu anomalies that are absent for metamorphic zircons grown from aqueous fluids. The zircon U. Pb ages of 217. ±. 2 to 226. ±. 3. Ma are close to, but slightly younger than, known ages for major UHP metamorphism in the Sulu orogen. Therefore, the UHP gneiss experienced incipient melting during the initial exhumation subsequent to the peak UHP metamorphism and extensive anatexis later at lower pressures. Muscovite relicts coexist with cuspate feldspars, suggesting that the anatectic melts originate from dehydration melting due to decompression breakdown of phengitic muscovite in the UHP granitic gneiss. As the degree of partial melting increases with temperature, significant fractions of the anatectic melts would be produced in the regional gneiss provided that the UHP rocks experienced "hot" exhumation. Such melts can be gathered together, being eventually emplaced as synexhumation granitic intrusions. © 2012 Elsevier B.V.

Wu Y.-B.,Wuhan University | Zheng Y.-F.,Hefei University of Technology
Gondwana Research | Year: 2013

The formation of collisional orogens is a prominent feature in convergent plate margins. It is generally a complex process involving multistage tectonism of compression and extension due to continental subduction and collision. The Paleozoic convergence between the South China Block (SCB) and the North China Block (NCB) is associated with a series of tectonic processes such as oceanic subduction, terrane accretion and continental collision, resulting in the Qinling-Tongbai-Hong'an-Dabie-Sulu orogenic belt. While the arc-continent collision orogeny is significant during the Paleozoic in the Qinling-Tongbai-Hong'an orogens of central China, the continent-continent collision orogeny is prominent during the early Mesozoic in the Dabie-Sulu orogens of east-central China. This article presents an overview of regional geology, geochronology and geochemistry for the composite orogenic belt. The Qinling-Tongbai-Hong'an orogens exhibit the early Paleozoic HP-UHP metamorphism, the Carboniferous HP metamorphism and the Paleozoic arc-type magmatism, but the three tectonothermal events are absent in the Dabie-Sulu orogens. The Triassic UHP metamorphism is prominent in the Dabie-Sulu orogens, but it is absent in the Qinling-Tongbai orogens. The Hong'an orogen records both the HP and UHP metamorphism of Triassic age, and collided continental margins contain both the juvenile and ancient crustal rocks. So do in the Qinling and Tongbai orogens. In contrast, only ancient crustal rocks were involved in the UHP metamorphism in the Dabie-Sulu orogenic belt, without involvement of the juvenile arc crust. On the other hand, the deformed and low-grade metamorphosed accretionary wedge was developed on the passive continental margin during subduction in the late Permian to early Triassic along the northern margin of the Dabie-Sulu orogenic belt, and it was developed on the passive oceanic margin during subduction in the early Paleozoic along the northern margin of the Qinling orogen. Three episodes of arc-continent collision are suggested to occur during the Paleozoic continental convergence between the SCB and NCB. The first episode of arc-continent collision is caused by northward subduction of the North Qinling unit beneath the Erlangping unit, resulting in UHP metamorphism at ca. 480-490. Ma and the accretion of the North Qinling unit to the NCB. The second episode of arc-continent collision is caused by northward subduction of the Prototethyan oceanic crust beneath an Andes-type continental arc, leading to granulite-facies metamorphism at ca. 420-430. Ma and the accretion of the Shangdan arc terrane to the NCB and reworking of the North Qinling, Erlangping and Kuanping units. The third episode of arc-continent collision is caused by northward subduction of the Paleotethyan oceanic crust, resulting in the HP eclogite-facies metamorphism at ca. 310. Ma in the Hong'an orogen and low-P metamorphism in the Qinling-Tongbai orogens as well as crustal accretion to the NCB. The closure of backarc basins is also associated with the arc-continent collision processes, with the possible cause for granulite-facies metamorphism. The massive continental subduction of the SCB beneath the NCB took place in the Triassic with the final continent-continent collision and UHP metamorphism at ca. 225-240. Ma. Therefore, the Qinling-Tongbai-Hong'an-Dabie-Sulu orogenic belt records the development of plate tectonics from oceanic subduction and arc-type magmatism to arc-continent and continent-continent collision. © 2012 International Association for Gondwana Research.

Chen Y.-X.,Hefei University of Technology | Zheng Y.-F.,Hefei University of Technology | Hu Z.,Wuhan University
Journal of Metamorphic Geology | Year: 2013

Petrological evidence is provided for anatexis of ultrahigh-pressure (UHP) metamorphic quartzite in the Sulu orogen. Some feldspar grains exhibit elongated, highly cuspate shapes or occur as interstitial, cuspate phases constituting interconnected networks along grain boundaries. Elongated veinlets composed of plagioclase + quartz ± K-feldspar also occur in grain boundaries. These features provide compelling evidence for anatexis of the UHP quartzite. Zircon grains from impure quartzite are all metamorphic growth with highly irregular shape. They contain inclusions of coesite, jadeite, rutile and lower pressure minerals, including multiphase solid inclusions that are composed of two or more phases of muscovite, quartz, K-feldspar and plagioclase. All zircon grains exhibit steep REE patterns, similar U-Pb ages and Hf isotope compositions with a weighted mean of 218 ± 2 Ma. Most grains have similar δ18O values of -0.6 to 0.1‰, but a few fall in the range -5.2 to -4.3‰. Thus, these grains would have grown from anatectic melts at various pressures. Zircon O isotope differences indicate that anatectic melts were derived from different sources with contrasting O isotopes, but similar Hf isotopes, that is, one from the quartzite itself and the other probably from the country-rock granitic gneiss. Zircon grains from pure quartzite contain relict magmatic cores and significant metamorphic overgrowths. Domains that contain eclogite facies minerals exhibit flat HREE patterns, no Eu anomalies and concordant U-Pb ages of c. 220 Ma. Similar U-Pb ages are also obtained for domains that contain lower pressure minerals and exhibit steep REE patterns and marked negative Eu anomalies. These observations indicate that zircon records subsolidus overgrowth at eclogite facies conditions but suprasolidus growth at lower pressures. Zircon enclosed by garnet gave consistent U-Pb ages of c. 214 Ma. Such garnet is interpreted as a peritectic product of the anatectic reaction that involves felsic minerals and possibly amphibole and titanite. The REE patterns of epidote and titanite also record multistage growth and metasomatism by anatectic melts. Therefore, the anatexis of UHP metamorphic rocks is evident during continental collision in the Triassic. © 2012 Blackwell Publishing Ltd.

Chen Y.-X.,Hefei University of Technology | Zheng Y.-F.,Hefei University of Technology | Hu Z.,Wuhan University
Lithos | Year: 2013

An integrated study of petrology, geochronology and geochemistry was performed for ultrahigh-pressure metamorphic gneisses in the Sulu orogen. The results are used to elucidate the polyphase growth of such metamorphic minerals as zircon, titanite and garnet in response to pressure-temperature changes and fluid/melt action during continental collision. This provides insights into the property of metamorphic fluid/melt and their effects on trace element mobility. A combined result from REE patterns, mineral inclusions and Ti-in-zircon temperatures indicates three stages of zircon growth. Prograde growth occurred at ~. 237. Ma primarily at eclogite-facies, retrograde growth at ~. 222. Ma mostly at eclogite-facies, and the last growth at ~. 205. Ma at granulite-facies. The three stages of zircon growth are deciphered by distinct REE patterns and trace element compositions, reflecting the differences in the property of metamorphic fluid/melt. The episodic growth of metamorphic zircon is primarily dictated by the episodic concentration of Zr and Si in metamorphic fluid/melt. Relict domains of magmatic titanite are distinguished from metamorphosed and metamorphic domains by their distinctive REE patterns and trace element compositions. The metamorphic titanite exhibit variably elevated Nb contents and Nb/Ta ratios, suggesting Nb/Ta fractionation due to breakdown of amphibole and/or biotite during metamorphism. Polyphase growth of garnet is suggested by an integrated analysis of mineral inclusions, and major and trace elements in large garnet grains. Trace element abundances vary in different zones of garnet, which is ascribed to changes in the paragenesis and composition of matrix minerals involved in garnet-forming reactions at different P-T conditions. Therefore, the metamorphic growth of zircon, titanite and garnet would have occurred not only during prograde subduction but also during retrograde exhumation in the continental collision zones. Both metamorphic dehydration and partial melting would have taken place episodically during the collisional orogeny. The breakdown of hydrous minerals at high- to ultrahigh-pressure conditions is a key to fluid liberation and element supply for the growth of these accessory minerals. © 2013 Elsevier B.V.

Zhang L.-F.,Hefei University of Technology | Zhang L.-F.,Jiangxi Normal University | Zhong S.-L.,Jiangxi Normal University | Xu A.-W.,Hefei University of Technology
Angewandte Chemie - International Edition | Year: 2013

Superstar: Branched concave Au/Pd bimetallic nanocrystals (see picture) were synthesized in high yield by seed-mediated co-reduction of Au and Pd metal precursors in an aqueous solution at room temperature. The branches are concave and have high-index facets on their surfaces. These nanocrystals show superior electrocatalytic activity for the oxidation of ethanol and highly efficient SERS enhancement. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Yan L.,University of South Carolina | Ding H.,University of South Carolina | Zhu Z.,Hefei University of Technology | Xue X.,University of South Carolina
Journal of Power Sources | Year: 2011

Cobalt-free perovskite Ba0.95La0.05FeO 3-δ (BLF) was synthesized. The conductivity of BLF was measured with a DC four-point technique. The thermal expansion coefficient of the BLF was measured using a dilatometer. The BaZr0.1Ce0.7Y 0.2O3-δ (BZCY7) electrolyte based proton conducting solid oxide fuel cells (SOFCs) were fabricated. A composite cathode with BLF + BZCY7 was used to mitigate the thermal expansion mismatch with the BZCY7 electrolyte. The polarization processes of the button cell NiO-BZCY7/BZCY7/BLF + BZCY7 were characterized using the complicated electrochemical impedance spectroscopy technique. The open circuit voltage of 0.982 V, 1.004 V, and 1.027 V was obtained at 700 °C, 650 °C, and 600 °C, respectively, while the peak power density of 325 mW cm-2, 240 mW cm-2, and 152 mW cm-2, was achieved accordingly. © 2011 Published by Elsevier B.V. All rights reserved.

Yin Y.W.,Pennsylvania State University | Yin Y.W.,Hefei University of Technology | Burton J.D.,University of Nebraska - Lincoln | Kim Y.-M.,Oak Ridge National Laboratory | And 9 more authors.
Nature Materials | Year: 2013

The range of recently discovered phenomena in complex oxide heterostructures, made possible owing to advances in fabrication techniques, promise new functionalities and device concepts. One issue that has received attention is the bistable electrical modulation of conductivity in ferroelectric tunnel junctions (FTJs) in response to a ferroelectric polarization of the tunnelling barrier, a phenomenon known as the tunnelling electroresistance (TER) effect. Ferroelectric tunnel junctions with ferromagnetic electrodes allow ferroelectric control of the tunnelling spin polarization through the magnetoelectric coupling at the ferromagnet/ferroelectric interface. Here we demonstrate a significant enhancement of TER due to a ferroelectrically induced phase transition at a magnetic complex oxide interface. Ferroelectric tunnel junctions consisting of BaTiO3 tunnelling barriers and La 0.7Sr0.3MnO3 electrodes exhibit a TER enhanced by up to ∼ 10,000% by a nanometre-thick La0.5Ca 0.5MnO3 interlayer inserted at one of the interfaces. The observed phenomenon originates from the metal-to-insulator phase transition in La0.5Ca0.5MnO3, driven by the modulation of carrier density through ferroelectric polarization switching. Electrical, ferroelectric and magnetoresistive measurements combined with first-principles calculations provide evidence for a magnetoelectric origin of the enhanced TER, and indicate the presence of defect-mediated conduction in the FTJs. The effect is robust and may serve as a viable route for electronic and spintronic applications. © 2013 Macmillan Publishers Limited. All rights reserved.

Xu X.-X.,Jiangxi Normal University | Yuan H.-C.,Changzhou Institute of Technology | Fan H.-Y.,Hefei University of Technology
Journal of the Optical Society of America B: Optical Physics | Year: 2015

A scheme for conditional generating Hermite polynomial excited squeezed vacuum states (HPESVS) is proposed. Injecting a two-mode squeezed vacuum state (TMSVS) into a beam splitter (BS) and counting the photons in one of the output channels, the conditional state in the other output channel is just a HPESVS. To exhibit a number of nonclassical effects and non-Gaussianity, we mainly investigate the photon number distribution, sub-Poissonian distribution, quadrature component distribution, and Wigner function of the conditional HPESVS. We find that its nonclassicality closely relates to the control parameter of the BS, the squeezed parameter of TMSVS, and the photon number of conditional measurement. These further demonstrate that performing the conditional measurement on a BS is an effective approach to generate non-Gaussian state. © 2015 Optical Society of America.

Chen R.-X.,Hefei University of Technology | Zheng Y.-F.,Hefei University of Technology | Hu Z.,Wuhan University
Lithos | Year: 2012

A combined study of mineral compositions and zircon U-Pb ages was carried out for a zoisite-quartz vein and its host retrograded eclogite in the Dabie orogen. The results reveal two episodes of fluid action during exhumation of the deeply subducted continental crust. The vein has a mineral paragenesis of quartz + zoisite + epidote + white mica + garnet + rutile + zircon + apatite, which is almost the same as that of the host retrograded eclogite characterized by symplectites after omphacite and/or garnet in the eclogite. Residues of magmatic zircon in the vein are similar to those in the eclogite, suggesting local sources of the metamorphic fluid for veining and physical transport of the tiny accessory mineral from the host rock to veins. There are significant differences in major and trace elements between vein-forming minerals, which are attributed to two episodes of fluid action for veining. Metamorphic zircon from the vein yields concordant U-Pb ages of 215 ± 4 to 218 ± 4. Ma. Trace element analysis indicates its precipitation from aqueous fluid during two distinct episodes under eclogite-facies and amphibolite-facies conditions, respectively. Ti-in-zircon and Zr-in-rutile thermometries yield variable temperatures from 537 to 683 °C. Thus the veining postdates the UHP metamorphic event at 225-240. Ma and took place during transition from HP eclogite-facies recrystallization to amphibolite-facies retrogression during the exhumation. The host eclogite was also retrograded in this stage to form metabasites such as amphibole eclogite to garnet amphibolite. The abundant occurrence of zoisite, epidote and phengite in the vein suggests that the metamorphic fluid is rich in Si, Al, Ca and K. The fluid composition is estimated in terms of zoisite composition and zoisite/fluid partition coefficients. The results suggest strong enrichment of LREE, Th, U, Pb, Sr, Rb and Ba, moderate enrichment of HREE, but significant depletion of HFSE. In this regard, the occurrence of metamorphic zircon and rutile in the vein suggests very local saturation of Zr and Ti in the Zo-Qtz vein-forming fluid. Therefore, the two episodes of fluid action would occur at the transition from eclogite to amphibolite facies during the exhumation and proceed with different fluid compositions and different flow behaviors. One was channelized under the eclogite-facies conditions, whereas the other is pervasive under the amphibolite-facies conditions. This provides robust constraints on the time, origin and property of metamorphic fluid during the exhumation of deeply subducted continental crust. © 2012 Elsevier B.V.

He D.,Wuhan University | Tian M.,Hefei University of Technology | Chen J.,Wuhan University
Information Sciences | Year: 2014

Recently, Xiong et al. [H. Xiong, Z. Guan, Z. Chen, F. Li, An efficient certificateless aggregate signature with constant pairing computations, Information Science 219 (2013) 225-235] proposed a certificateless signature (CLS) scheme and used it to construct a certificateless aggregate signature (CLAS) scheme with constant pairing computations. They demonstrated that both of their schemes are provably secure in the random oracle model under the computational Diffie-Hellman assumption. Unfortunately, by giving concrete attack, we demonstrate that their schemes are not secure against the Type II adversary, i.e. a Type II adversary could forge a legal signature of any message. © 2013 Elsevier Inc. All rights reserved.

Gao X.-Y.,Hefei University of Technology | Zheng Y.-F.,Hefei University of Technology | Chen Y.-X.,Hefei University of Technology | Guo J.,Wuhan University
Lithos | Year: 2012

Relict magmatic titanite was identified in the core of a few titanite grains with the overgrown rim of metamorphic titanite in UHP metagranite in the Dabie orogen. LA-ICPMS U-Pb dating gave Neoproterozoic ages for the magmatic titanite but Triassic ages for the metamorphic titanite. The magmatic and metamorphic titanites are clearly distinct by differences in petrological and geochemical compositions. The magmatic titanite occurs as residual cores that show bright BSE, the presence of allanite and quartz inclusions, low contents of CaO, Al 2O 3 and TiO 2 but high contents of Fe 2O 3 and MgO. In trace elements, the magmatic titanite exhibits high REE and HFSE contents, distinctly negative Eu anomalies with flat MREE-HREE patterns, and high Th/U ratios. In contrast, the metamorphic titanite occurs as rims and grains of homogeneously dark BSE that contain inclusions of epidote, quartz, K-feldspar, rutile, biotite and phengite, and have relatively high contents of CaO, Al 2O 3 and TiO 2, but low contents of Fe 2O 3 and MgO, and relatively low REE and HFSE contents, slightly negative Eu anomalies with HREE depletion relative to MREE, and low Th/U ratios. The Zr-in-titanite thermometry yields 727 to 877°C at 0.5 to 1.0GPa for the magmatic titanite, and 729 to 870°C at 1.5 to 2.0GPa for the metamorphic titanite. The Neoproterozoic U-Pb chronometric system of magmatic titanite survived the Triassic continental subduction-zone HP-UHP metamorphism. This suggests a relatively high closure temperature of >800°C for the titanite U-Pb system. The metamorphic titanite is principally a product of retrograde metamorphism during decompression exhumation at the transition from HP eclogite-facies to amphibolite-facies. Therefore, titanite holds a great potential to geochronological and petrogenetic studies of continental subduction-zone metamorphic rocks. © 2011 Elsevier B.V.

Leng W.,Hefei University of Technology | Leng W.,National Geophysical Observatory at Mengcheng | Gurnis M.,California Institute of Technology
Geophysical Research Letters | Year: 2015

Although plate tectonics is well established, how a new subduction zone initiates remains controversial. Based on plate reconstruction and recent ocean drilling within the Izu-Bonin-Mariana, we advance a new geodynamic model of subduction initiation (SI). We argue that the close juxtaposition of the nascent plate boundary with relic oceanic arcs is a key factor localizing initiation of this new subduction zone. The combination of thermal and compositional density contrasts between the overriding relic arc, and the adjacent old Pacific oceanic plate promoted spontaneous SI. We suggest that thermal rejuvenation of the overriding plate just before 50 Ma caused a reduction in overriding plate strength and an increase in the age contrast (hence buoyancy) between the two plates, leading to SI. The computational models map out a framework in which rejuvenated relic arcs are a favorable tectonic environment for promoting subduction initiation, while transform faults and passive margins are not. ©2015. American Geophysical Union. All Rights Reserved.

Zhang W.,Hefei University of Technology | Zhang W.,CAS Zhengzhou Research Institute | Chen B.,Hefei University of Technology | Yu N.,Hefei University of Technology
IEEE Transactions on Image Processing | Year: 2012

In reversible data hiding (RDH), the original cover can be losslessly restored after the embedded information is extracted. Kalker and Willems established a rate-distortion model for RDH, in which they proved out the rate-distortion bound and proposed a recursive code construction. In our previous paper, we improved the recursive construction to approach the rate-distortion bound. In this paper, we generalize the method in our previous paper using a decompression algorithm as the coding scheme for embedding data and prove that the generalized codes can reach the rate-distortion bound as long as the compression algorithm reaches entropy. By the proposed binary codes, we improve three RDH schemes that use binary feature sequence as covers, i.e., an RS scheme for spatial images, one scheme for JPEG images, and a pattern substitution scheme for binary images. The experimental results show that the novel codes can significantly reduce the embedding distortion. Furthermore, by modifying the histogram shift (HS) manner, we also apply this coding method to one scheme that uses HS, showing that the proposed codes can be also exploited to improve integer-operation-based schemes. © 2012 IEEE.

Xia Q.-X.,Hefei University of Technology | Zheng Y.-F.,Hefei University of Technology | Hu Z.,Wuhan University
Lithos | Year: 2010

Simultaneously in-situ analyses of U-Pb isotopes and trace elements were carried out for zircons, in combination with the in-situ analyses of trace elements in coexisting minerals, from low-T/UHP metagranite in the Dabie orogen. The results provide geochemical evidence for the existence of supercritical fluid during continental subduction-zone metamorphism. The zircons are categorized into three types based on their patterns of REE distribution. Type I zircons show increasing enrichment from La to Lu, with prominent positive Ce anomalies and negative Eu anomalies, which are typical of magmatic zircon. Some of them display regular or blurred oscillatory-zoned texture and apparent 206Pb/238U ages of 341 to 780 Ma, suggesting metamorphic modification by solid-state recrystallization with no significant involvement of metamorphic fluid. Type II zircons share similar Th, U and HFSE contents and REE patterns to Type I zircons. However, they exhibit blurred oscillatory-zoned texture or are unzoned, have apparent 206Pb/238U ages of 348 to 709 Ma, and are LREE-enriched relative to Type I zircons. This suggests that they underwent metamorphic reworking by replacement recrystallization in the presence of metamorphic fluid. The LREE enrichment is due to the presence of microscale LREE-bearing mineral inclusions (such as apatite, monazite or epidote) in the zircons. Type III zircons, representing the majority of the present analyses, are characterized by spongy texture and consistent enrichment of LREE, HREE, Th, U and HFSE relative to Type I zircons. They yield nearly concordant U-Pb ages close to the discordia lower-intercept. The consistent enrichment of trace elements relative to the magmatic zircon indicates involvement of a special UHP metamorphic fluid that has a strong capacity to extract significant amounts of LREE, HREE, Th, U and HFSE from such accessory minerals as allanite, garnet, rutile and zircon. Because these minerals are stable in the field of hydrous melt in granite-water systems, they are not able to be decomposed during the exhumation of deeply subducted continental crust. Thus, a supercritical fluid is suggested to transport the LREE, HREE, Th, U and HFSE in the accessory minerals to recrystallized zircons. The mechanism of dissolution recrystallization is responsible for the spongy texture and the very high concentration of trace elements in this type of metamorphic zircons. Therefore, the action of supercritical fluid is evident under the low-T/UHP metamorphic conditions. © 2009 Elsevier B.V. All rights reserved.

Wang Y.-M.,Fuzhou University | Wang Y.-M.,Hefei University of Technology
International Journal of Production Research | Year: 2012

Quality function deployment (QFD) is often implemented to transform customer requirements (CRs) into the engineering design requirements (DRs) of a new product. Prioritising engineering DRs is essential to reasonably allocate resources for the new product development, and often must be done under uncertainty due to the vagueness and impreciseness of the judgments made by customers and QFD team members, and is a typical group decision behaviour that requires the active participation of multiple customers and multiple QFD design team members. Fuzzy set theory provides a theoretical basis for solving such group decision-making problems under uncertainty. Existing approaches for prioritising DRs under uncertainty usually simplify the group decision-making problem as non-group decision making for solution by simply aggregating individuals opinions using their arithmetic averages. This paper proposes a different fuzzy group decision-making procedure for prioritising DRs under uncertainty. The proposed approach does not aggregate the individual judgments of customers and QFD design team members, but rather aggregates the technical importance ratings of DRs, and can produce more rational and robust priority rankings for DRs through fuzzy normalisation. A real design case of a flexible manufacturing system (FMS) is examined to show the effectiveness and the potential applications of the proposed approach. Results are compared with those obtained by two known approaches. © 2012 Copyright Taylor and Francis Group, LLC.

Feng Z.-H.,Hefei University of Technology | Feng Z.-H.,Beijing Institute of Technology | Zou L.-L.,CAS Institute of Policy and Management | Wei Y.-M.,Beijing Institute of Technology
Energy | Year: 2011

In this paper, the consumer lifestyle approach is applied to analyze the impact of consumption by urban and rural households on energy use and CO2 emissions for different regions and income levels in China. Grey Model is used to compare the relationship between energy consumption, consumption expenditure and CO2 emissions for different lifestyles. The results show that direct energy consumption is diverse for urban households and simple for rural households in China. Direct energy consumption and CO2 emissions are increasing faster for urban than for rural households. Indirect energy consumption and CO2 emissions for urban households are much greater than the direct consumption values. The total indirect energy consumption and CO2 emissions differ by regions and the structures are different, but the latter differences are not obvious. The impact of household income is enormous. Indirect energy consumption and CO2 emissions are higher for high-income than for low-income households. The structural difference for indirect energy consumption and CO2 emissions for households with different income levels is significant. The higher the income, the more diverse is the energy consumption and CO2 emission structure. The structures for indirect energy use and CO2 emissions are diverse for urban households, but simple for rural households. © 2010.

Zhu G.,Hefei University of Technology | Jiang D.,University of Western Ontario | Zhang B.,Hefei University of Technology | Chen Y.,Hefei University of Technology | Chen Y.,University of Western Ontario
Gondwana Research | Year: 2012

The eastern North China Craton (NCC) west of the Pacific Ocean has a long history of rifting from Early Cretaceous to the end of Paleogene when the craton experienced destruction and significant thinning of the lithosphere. The cause and geotectonic environment for this destruction remain controversial. We use a set of field observation including basin patterns, fault geometry and kinematics, fault plane slip data, dike distribution, and fabric data from metamorphic core complexes to determine the kinematic evolution of the deformation in the eastern NCC during this period. We show that the principal extension direction in the eastern NCC evolved from WNW-ESE in the earliest-middle Early Cretaceous, via NW-SE in the latest Early Cretaceous, to nearly N-S in the Late Cretaceous-Paleogene. The movement history, from Late Mesozoic to Early Cenozoic, of the oceanic plates in the Pacific Ocean with respect to the eastern NCC is available from previous studies. The Izanagi Plate first subducted nearly orthogonally (WNW-wards) during earliest-middle Early Cretaceous time, and then moved obliquely (NNW-wards) in the latest Early Cretaceous while the relaying Pacific Plate moved generally northwards from the Late Cretaceous to Paleogene. Both the movement direction of oceanic plates and the principal extension direction of the continental deformation rotated clockwise. We suggest that such a correlation can be explained by the eastern NCC being in a backarc setting in the Cretaceous-Paleogene period. The results support the backarc extensional model for the destruction and significant lithospheric thinning of the eastern NCC. © 2011 International Association for Gondwana Research.

Ren T.-T.,University of Hong Kong | Ren T.-T.,Hefei University of Technology | Li X.-Y.,University of Hong Kong | Yu H.-Q.,Hefei University of Technology
Bioresource Technology | Year: 2013

A laboratory study was conducted to investigate the production of quorum sensing (QS) molecules by aerobic granules in membrane-partitioned bioreactor. Flow-chamber (FC) tests with Escherichia coli K12 demonstrated that granules induced more attached growth of E. coli cells than activated sludge flocs, leading to more cell adhesion and biofilm formation on the FC cover slide. Using the thin-layer chromatography, N-acy- l-homoserine lactones (AHLs) with acyl chains shorter than 10 carbons were detected in the liquid phase of granular sludge. Organic substances extracted with acidified ethyl acetate from the supernatant of granular sludge promoted the adhesion and growth of E. coli cells on the glass surface. AHL-like signal molecules were apparently produced by granules and might be involved in the formation of granules and the maintenance of granular structures during wastewater treatment. © 2012 Elsevier Ltd.

Wu Z.,Hefei University of Technology | Bouklas N.,University of Texas at Austin | Huang R.,University of Texas at Austin
International Journal of Solids and Structures | Year: 2013

Upon swelling in a solvent, a thin hydrogel layer on a rigid substrate may become unstable, developing various surface patterns. Recent experimental studies have explored the possibilities to generate controllable surface patterns by chemically modifying the molecular structures of the hydrogel near the surface. In this paper, we present a theoretical stability analysis for swelling of hydrogel layers with material properties varying in the thickness direction. As a specialization of the general procedure, hydrogel bilayers with different combinations of the material properties are examined in details. For a soft-on-hard bilayer, the onset of surface instability is determined by the short-wave limit, similar to a homogeneous layer. In contrast, for a hard-on-soft bilayer, a long-wave mode with a finite wavelength emerges as the critical mode at the onset of surface instability, similar to wrinkling of an elastic thin film on a compliant substrate, and the critical swelling ratio is much lower than that for a homogeneous hydrogel layer. A smooth transition of the critical mode is predicted as the volume fraction of the top layer changes, linking surface instability of a homogeneous layer to thin film wrinkling as two limiting cases. The results from the present study suggest that both the critical condition and the instability mode depend sensitively on the variation of the material properties in the thickness direction of the hydrogel layer. © 2012 Elsevier Ltd. All rights reserved.

Fang S.-E.,Fuzhou University | Ren W.-X.,Hefei University of Technology | Perera R.,Technical University of Madrid
Mechanical Systems and Signal Processing | Year: 2012

Stochastic model updating must be considered for quantifying uncertainties inherently existing in real-world engineering structures. By this means the statistical properties, instead of deterministic values, of structural parameters can be sought indicating the parameter variability. However, the implementation of stochastic model updating is much more complicated than that of deterministic methods particularly in the aspects of theoretical complexity and low computational efficiency. This study attempts to propose a simple and cost-efficient method by decomposing a stochastic updating process into a series of deterministic ones with the aid of response surface models and Monte Carlo simulation. The response surface models are used as surrogates for original FE models in the interest of programming simplification, fast response computation and easy inverse optimization. Monte Carlo simulation is adopted for generating samples from the assumed or measured probability distributions of responses. Each sample corresponds to an individual deterministic inverse process predicting the deterministic values of parameters. Then the parameter means and variances can be statistically estimated based on all the parameter predictions by running all the samples. Meanwhile, the analysis of variance approach is employed for the evaluation of parameter variability significance. The proposed method has been demonstrated firstly on a numerical beam and then a set of nominally identical steel plates tested in the laboratory. It is found that compared with the existing stochastic model updating methods, the proposed method presents similar accuracy while its primary merits consist in its simple implementation and cost efficiency in response computation and inverse optimization. © 2012 Elsevier Ltd.

Wang Y.-M.,Fuzhou University | Wang Y.-M.,Hefei University of Technology | Jiang P.,Chongqing Technology and Business University
Computers and Industrial Engineering | Year: 2012

A mixed integer linear model for selecting the best decision making unit (DMU) in data envelopment analysis (DEA) has recently been proposed by Foroughi [Foroughi, A. A. (2011a). A new mixed integer linear model for selecting the best decision making units in data envelopment analysis. Computers and Industrial Engineering, 60(4), 550-554], which involves many unnecessary constraints and requires specifying an assurance region (AR) for input weights and output weights, respectively. Its selection of the best DMU is easy to be affected by outliers and may sometimes be incorrect. To avoid these drawbacks, this paper proposes three alternative mixed integer linear programming (MILP) models for identifying the most efficient DMU under different returns to scales, which contain only essential constraints and decision variables and are much simpler and more succinct than Foroughi's. The proposed alternative MILP models can make full use of input and output information without the need of specifying any assurance regions for input and output weights to avoid zero weights, can make correct selections without being affected by outliers, and are of significant importance to the decision makers whose concerns are not DMU ranking, but the correct selection of the most efficient DMU. The potential applications of the proposed alternative MILP models and their effectiveness are illustrated with four numerical examples. © 2011 Elsevier Ltd. All rights reserved.

Xiong J.,Hefei University of Technology | Lam J.,University of Hong Kong | Shu Z.,University of Southampton | Mao X.,University of Strathclyde
IEEE Transactions on Automatic Control | Year: 2014

This technical note is concerned with the stability analysis of continuous-time switched systems with a random switching signal. The switching signal manifests its characteristics with that the dwell time in each subsystem consists of a fixed part and a random part. The stochastic stability of such switched systems is studied using a Lyapunov approach. A necessary and sufficient condition is established in terms of linear matrix inequalities. The effect of the random switching signal on system stability is illustrated by a numerical example and the results coincide with our intuition. © 2013 IEEE.

Sheng G.-P.,Hefei University of Technology | Yu H.-Q.,Hefei University of Technology | Li X.-Y.,University of Hong Kong
Biotechnology Advances | Year: 2010

A review concerning the definition, extraction, characterization, production and functions of extracellular polymeric substances (EPS) of microbial aggregates in biological wastewater treatment reactors is given in this paper. EPS are a complex high-molecular-weight mixture of polymers excreted by microorganisms, produced from cell lysis and adsorbed organic matter from wastewater. They are a major component in microbial aggregates for keeping them together in a three-dimensional matrix. Their characteristics (e.g., adsorption abilities, biodegradability and hydrophilicity/hydrophobicity) and the contents of the main components (e.g., carbohydrates, proteins, humic substances and nucleic acids) in EPS are found to crucially affect the properties of microbial aggregates, such as mass transfer, surface characteristics, adsorption ability, stability, the formation of microbial aggregates etc. However, as EPS are very complex, the knowledge regarding EPS is far from complete and much work is still required to fully understand their precise roles in the biological treatment process. © 2010 Elsevier Inc.

Chen Q.,Southwest Technique and Engineering Institute | Shu D.,Southwest Technique and Engineering Institute | Zhao Z.,Southwest Technique and Engineering Institute | Wang Y.,Southwest Technique and Engineering Institute | Yuan B.,Hefei University of Technology
Materials and Design | Year: 2012

The Mg-5.3. wt.%Zn-1.13. wt.%Nd-0.51. wt.%La-0.28. wt.%Pr-0.79. wt.%Zr alloy prepared by direct chill casting is subjected to hot extrusion. The effects of extrusion ratio and temperature on microstructure and tensile mechanical properties have been studied. The results indicate coarse grains of as-cast alloys are refined with extrusion ratio increasing from 0 to 9. The eutectic constituents are elongated along extrusion direction. However, further increase of extrusion ratio has a little influence on grain refinement and the improvement of mechanical properties of the alloy. Dynamic recrystallisation is the main mechanism of grain refinement during hot extrusion. Raising extrusion temperature results in grain coarsening. Grain shape becomes more equiaxed-like with raising extrusion temperature. At the same time, mechanical properties decrease with the increase of extrusion temperature. © 2012 Elsevier Ltd.

Zhang W.,Hefei University of Technology | Hu X.,Hefei University of Technology | Li X.,Beijing Institute of Technology | Yu N.,Hefei University of Technology
IEEE Transactions on Image Processing | Year: 2013

State-of-the-art schemes for reversible data hiding (RDH) usually consist of two steps: first construct a host sequence with a sharp histogram via prediction errors, and then embed messages by modifying the histogram with methods, such as difference expansion and histogram shift. In this paper, we focus on the second stage, and propose a histogram modification method for RDH, which embeds the message by recursively utilizing the decompression and compression processes of an entropy coder. We prove that, for independent identically distributed (i.i.d.) gray-scale host signals, the proposed method asymptotically approaches the rate-distortion bound of RDH as long as perfect compression can be realized, i.e., the entropy coder can approach entropy. Therefore, this method establishes the equivalency between reversible data hiding and lossless data compression. Experiments show that this coding method can be used to improve the performance of previous RDH schemes and the improvements are more significant for larger images. © 1992-2012 IEEE.

Zhang L.L.,University of Texas at Austin | Zhao X.,University of Texas at Austin | Zhao X.,Donghua University | Stoller M.D.,University of Texas at Austin | And 8 more authors.
Nano Letters | Year: 2012

We present a novel method to prepare highly conductive, free-standing, and flexible porous carbon thin films by chemical activation of reduced graphene oxide paper. These flexible carbon thin films possess a very high specific surface area of 2400 m 2 g -1 with a high in-plane electrical conductivity of 5880 S m -1. This is the highest specific surface area for a free-standing carbon film reported to date. A two-electrode supercapacitor using these carbon films as electrodes demonstrated an excellent high-frequency response, an extremely low equivalent series resistance on the order of 0.1 ohm, and a high-power delivery of about 500 kW kg -1. While higher frequency and power values for graphene materials have been reported, these are the highest values achieved while simultaneously maintaining excellent specific capacitances and energy densities of 120 F g -1 and 26 W h kg -1, respectively. In addition, these free-standing thin films provide a route to simplify the electrode-manufacturing process by eliminating conducting additives and binders. The synthetic process is also compatible with existing industrial level KOH activation processes and roll-to-roll thin-film fabrication technologies. © 2012 American Chemical Society.

Zhu H.,Brown University | Zhang S.,Brown University | Huang Y.-X.,Brown University | Huang Y.-X.,Hefei University of Technology | And 2 more authors.
Nano Letters | Year: 2013

Sub-10 nm nanoparticles (NPs) of M(II)-substituted magnetite M xFe3-xO4 (MxFe 1-xO•Fe2O3) (M = Mn, Fe, Co, Cu) were synthesized and studied as electrocatalysts for oxygen reduction reaction (ORR) in 0.1 M KOH solution. Loaded on commercial carbon support, these M xFe3-xO4 NPs showed the M(II)-dependent ORR catalytic activities with MnxFe3-xO4 being the most active followed by CoxFe3-xO4, Cu xFe3-xO4, and Fe3O4. The ORR activity of the MnxFe3-xO4 was further tuned by controlling x and MnFe2O4 NPs were found to be as efficient as the commercial Pt in catalyzing ORR. The MnFe2O 4 NPs represent a new class of highly efficient non-Pt catalyst for ORR in alkaline media. © 2013 American Chemical Society.

Han D.,Hefei University of Technology | Han D.,China Tobacco Chuanyu Industrial Co. | Yan L.,Hefei University of Technology
ACS Sustainable Chemistry and Engineering | Year: 2014

Biomass-based materials are attractive due to their renewability, biodegradability, and biocompatibility. Chitosan is a typical biomacromolecule that can be used as feedstock for novel materials. Here, the self-assembly of chitosan chains with graphene oxide (GO) nanosheets has been studied, where GO works as the two-dimensional cross-linker dues to its multifunctional groups on both sides. Supramolecular hydrogels of chitosan and GO have been prepared by controlling the concentration of GO, ratio of chitosan to GO, and temperature. It was found that at high GO concentration, hydrogel can be obtained at room temperature, and the as-prepared hydrogel showed a self-healing performance. However, at low GO concentration, the supramolecular hydrogel formed only at high temperature (95 °C). The driving force for the hydrogel is believed to be the noncovalent interactions. The reversible hydrogels have potential applications in fields of biomaterials, wastewater treatment, and smart materials. © 2013 American Chemical Society.

Bresch D.,CNRS Mathematics Laboratory | Huang X.,Hefei University of Technology
Archive for Rational Mechanics and Analysis | Year: 2011

This paper mainly concerns the mathematical justification of a viscous compressible multi-fluid model linked to the Baer-Nunziato model used by engineers, see for instance Ishii (Thermo-fluid dynamic theory of two-phase flow, Eyrolles, Paris, 1975), under a "stratification" assumption. More precisely, we show that some approximate finite-energy weak solutions of the isentropic compressible Navier-Stokes equations con