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Tianjin, China

Tianjin University is a national university under the direct administration of the Ministry of Education of China. It is the first modern higher education institution in China. It was established in 1895 as Tientsin University/Imperial Tientsin University and later Peiyang University . In 1951, after restructuring, it was renamed Tianjin University, and became one of the largest multidisciplinary engineering universities in China. The university was one of the first 16 universities accredited by the State in 1959. It is also among the first group of institutions of higher learning in the national “211-Project” to which priority is given in construction. In order to carry out the “21st Century Education Revitalizing Action Plan”, in late 2000 the Ministry of Education and Tianjin Municipality signed an agreement which aims to build Tianjin University into a world famous university in the 21st Century. Wikipedia.

Li Y.Q.,Tianjin University
Zhongguo zhen jiu = Chinese acupuncture & moxibustion | Year: 2011

The Medline database system and the CNKI literature database were used to evaluate the publications in acupuncture in recent years, using the key words: "acupuncture" "adverse reaction" and "risk". A number of 155 publications in Chinese were collected, including 698 cases; a number of 59 abstracts publications in English were selected, including 64 cases. The analysis of the publications shows that various causes lead to adverse reactions to acupuncture. The defective security system of acupuncture is one of the major causes. It demands to promote the safety guidelines issued by WHO or to establish a new Chinese security system of acupuncture.

Tian F.,China Institute of Medical Equipment | He C.N.,Tianjin University
Materials Chemistry and Physics | Year: 2010

The synthesis of carbon nanospheres (CNSs) by chemical vapor deposition (CVD) of methane on catalyst of Ni-Al composite powders was reported. The influence factors on the growth morphology of CNSs, such as reaction temperature, reaction time and different carrier gases concerning hydrogen, nitrogen as well as no carrier gas were investigated using transmission electron microscope. The results showed that the reaction temperature had great effect on the structure of CNSs, higher temperature led to high-crystallized CNSs with high purity. The reaction time brought no significant influence to the structure of CNSs, but the average diameter of the CNSs was obviously increased with prolonging the reaction time. Relatively pure CNSs could be obtained with hydrogen as the carrier gas but with poor product rate compared with the CNSs with no carrier gas. Proper amount of CNSs with pure characteristic could be obtained with nitrogen as the carrier gas. Finally, a growth mechanism of dissolution-precipitation-diffusion is proposed for elucidating the growth process of general CNSs. © 2010 Elsevier B.V. All rights reserved.

Xie M.,Tianjin Research Institute for Water Transport Engineering | Xie M.,Tianjin University
Ocean Modelling | Year: 2011

A three-dimensional numerical model was established to simulate the wave-induced currents. The depth-varying residual momentum, surface roller, wave horizontal and vertical turbulent mixing effects were incorporated as major driving forces. A surface roller evolution model considering the energy transfer, roller density and bottom slope dissipation was developed. The expression of the wave-induced horizontal turbulent mixing coefficient proposed by Larson and Kraus (1991) was extended to three-dimensional form. Plenty of experimental cases were used to validate the established model covering the wave setup, undertow, longshore currents and rip currents. Validation results showed the model could reasonably describe the main characteristics of different wave-induced current phenomena. The incorporation of surface roller for breaking waves should not be neglected in the modeling of surfzone hydrodynamics. The wave-induced turbulent mixing affects the structures of wave-induced current either in horizontal or in vertical directions. Sensitivity analysis of the major calibration parameters in the established model was made and their ranges were evaluated. © 2011 Elsevier Ltd.

Hou L.,Tianjin University
Applied Biochemistry and Biotechnology | Year: 2010

Fermentation properties under the control of multiple genes of industrial Saccharomyces cerevisiae strain are difficult to alter with traditional methods. Here, we describe efficient and reliable genome shuffling to increase ethanol production through the rapid improvement of stress resistance. The strategy is carried out using yeast sexual and asexual reproduction by itself instead of polyethylene glycol-mediated protoplast fusion. After three rounds of genome shuffling, the best performing strain S3-10 was obtained on the special plate containing a high ethanol concentration. It exhibits substantial improvement in multiple stress tolerance to ethanol, glucose, and heat. The cycle of fermentation of S3-10 was not only shortened, but also, ethanol yield was increased by up to 10.96% compared with the control in very-high-gravity (VHG) fermentations. In total, S3-10 possesses optimized fermentation characteristics, which will be propitious to the development of bioethanol fermentation industry. © 2009 Humana Press.

Chen Y.,Tianjin University
Diangong Jishu Xuebao/Transactions of China Electrotechnical Society | Year: 2014

Big amplitude sub-harmonics and higher order harmonics with same winding coefficient as fundamental component, especially the harmonics with same fundamental winding coefficient, different direction rotation, big amplitude and small pole number difference, all exists in the fractional-slot concentrated winding permanent magnet synchronous machine (PMSM) with few slots and multiple poles. These can lead to a strong armature reaction harmonic field, consequently with a significant harmonic leakage reactance and overall leakage inductance. Further, it can be found that the fundamental component magnetizing inductance is much lower than that of the traditional short pitch distributed winding PMSM, and the leakage inductance is bigger than the magnetizing inductance. Then the inductance calculation formulas are derived for such machines with varied number of slots and poles under ideal condition. The results show that the formula for the fundamental component of armature reaction magnetizing inductance is same as that for the traditional AC machines. However, the formulas for the armature reaction overall inductance and the harmonic leakage inductance are changed.

Sheng H.,Tianjin University | Chiang H.-D.,Cornell University
IEEE Transactions on Power Systems | Year: 2014

The widespread use of distributed generations (DGs) in utility distribution feeders is a trend, and it brings about several challenges to the operation, planning, and design of general distribution networks. In this paper, a comprehensive tool, Continuation Distribution Power Flow (CDFLOW), is presented and evaluated. CDFLOW can be used for tracing steady-state stationary behaviors of general unbalanced distribution systems due to various types of power injection variations, including high penetration of DGs. The major computation engine behind CDFLOW is the continuation method. Major components, either balanced or unbalanced, grounded or ungrounded, are well modeled in CDFLOW. A detailed description of CDFLOW and its implementation regarding the predictor, corrector, adaptive step-size control and parameterizations are presented. For illustrative purposes, CDFLOW was applied to the IEEE 8500-node test system and a practical 1103-node distribution networks with promising results. © 1969-2012 IEEE.

Chen Y.,Tianjin University of Science and Technology | Chen Y.,Tianjin University | Liu W.,Tianjin University of Science and Technology
Optics Letters | Year: 2012

A multilayered structure incorporating a metal-dielectric subwavelength grating, with the characteristic of polarization separation for visible light and the capability of creating reflection resonance and distinctive polarizationdependent color effects, is proposed. Its reflection resonance and color for TE and TM polarizations are discussed, as well as the influence of its structural parameters on them. Moreover, a reflection filter with characteristics of red for TE-polarized light, green for TM-polarized light, and yellow for daylight is designed and fabricated by replacing its grating region with a sinusoidal grating, and its related characteristics also are verified. The structure and its properties can achieve practical applications in various fields, such as color security, image reproduction, color filtering, and polarization-based information hiding. © 2011 Optical Society of America.

Pang Y.,Tianjin University | Yuan Y.,CAS Xian Institute of Optics and Precision Mechanic | Li X.,CAS Xian Institute of Optics and Precision Mechanic | Pan J.,Tianjin University of Technology and Education
Signal Processing | Year: 2011

While Histograms of Oriented Gradients (HOG) plus Support Vector Machine (SVM) (HOGSVM) is the most successful human detection algorithm, it is time-consuming. This paper proposes two ways to deal with this problem. One way is to reuse the features in blocks to construct the HOG features for intersecting detection windows. Another way is to utilize sub-cell based interpolation to efficiently compute the HOG features for each block. The combination of the two ways results in significant increase in detecting humansmore than five times better. To evaluate the proposed method, we have established a top-view human database. Experimental results on the top-view database and the well-known INRIA data set have demonstrated the effectiveness and efficiency of the proposed method. © 2010 Elsevier B.V. All rights reserved.

Shi J.,Tianjin University of Technology | Shi J.,Tianjin University | Jiang Y.,Hebei University of Technology | Wang X.,Tianjin University of Technology | And 5 more authors.
Chemical Society Reviews | Year: 2014

Organic-inorganic hybrid capsules, which typically possess a hollow lumen and a hybrid wall, have emerged as a novel and promising class of hybrid materials and have attracted enormous attention. In comparison to polymeric capsules or inorganic capsules, the hybrid capsules combine the intrinsic physical/chemical properties of the organic and inorganic moieties, acquire more degrees of freedom to manipulate multiple interactions, create hierarchical structures and integrate multiple functionalities. Thus, the hybrid capsules exhibit superior mechanical strength (vs. polymeric capsules) and diverse functionalities (vs. inorganic capsules), which may give new opportunities to produce high-performance materials. Much effort has been devoted to exploring innovative and effective methods for the synthesis of hybrid capsules that exhibit desirable performance in target applications. This tutorial review firstly presents a brief description of the capsular structure and hybrid materials in nature, then classifies the hybrid capsules into molecule-hybrid capsules and nano-hybrid capsules based upon the size of the organic and inorganic moieties in the capsule wall, followed by a detailed discussion of the design and synthesis of the hybrid capsules. For each kind of hybrid capsule, the state-of-the-art synthesis methods are described in detail and a critical comment is embedded. The applications of these hybrid capsules in biotechnological areas (biocatalysis, drug delivery, etc.) have also been summarized. Hopefully, this review will offer a perspective and guidelines for the future research and development of hybrid capsules. This journal is © the Partner Organisations 2014.

Xu J.,Tianjin University | Li Y.,Tianjin Agricultural University
Molecular Medicine Reports | Year: 2012

Intense exercise increases oxygen consumption and may produce an imbalance between reactive oxygen species (ROS) and antioxidants, inducing oxidative stress as a result of increased ROS production. Exogenous antioxidants may prevent oxidative damages since they are able to detoxify certain peroxides by scavenging the ROS produced during exercise. The aim of this study was to evaluate the effects of salidroside on exhaustive exercise-induced oxidative stress in rats. A total of 40 animals were randomly divided into four groups of ten rats each: control (C), low-dose salidroside-treated (LT), middle-dose salidroside-treated (MT) and high-dose salidroside-treated (HT) groups. The rats in the treated groups received salidroside (25, 50 and 100 mg/kg, respectively) intragastrically (ig) and the rats in the control group received drinking water ig for 4 weeks. After 4 weeks, the rats performed an exhaustive swimming exercise and exhaustive swimming times were recorded. The malondialdehyde (MDA), catalase (CAT), superoxide dismutase (SOD), glutathione peroxidase (GSH-Px) and glycogen levels in the liver tissues of the rats were measured. The data revealed that salidroside was able to elevate the exercise tolerance and increase the liver glycogen levels of the rats following exhaustive exercise. Salidroside was also able to reduce MDA levels and enhance the activities of antioxidant enzymes (CAT, SOD and GSH-Px) in the liver tissues of the rats. The results from this study indicate that salidroside is effective in the prevention of oxidative stress following exhaustive exercise.

Small SAPO-34 zeolites and thin membranes were synthesized by using triethylamine as the template and β-cyclodextrin as the crystal growth inhibitor (CGI). The thus obtained SAPO-34 membranes exhibited CO2-CH4 separation selectivities as high as 186. In addition, they displayed CO2 permeance values greater than 2.32 × 10-6 mol m-2 s-1 Pa-1. This journal is © the Partner Organisations 2014.

Liu S.,Tianjin University | Sandoval C.A.,CAS Shanghai Institute of Organic Chemistry
Journal of Molecular Catalysis A: Chemical | Year: 2010

The versatile calix[4]arene framework yielded chiral diphosphite ligands applicable for Rh-catalyzed asymmetric hydrogenation of dehydroamino acid derivatives. Optimum efficiency was obtained for: R1 =-C(CH 3)3; R2 =-CH2CH2CH 3; and R3 = H. © 2010 Elsevier B.V. All rights reserved.

Wang X.,Tianjin University
Zhen ci yan jiu = Acupuncture research / [Zhongguo yi xue ke xue yuan Yi xue qing bao yan jiu suo bian ji] | Year: 2011

To evaluate the clinical effect of acupuncture therapy for fibromyalgia syndrome (FMS) by analyzing the available studies so as to provide clinical decision-making reference. The published papers on clinical trails for acupuncture treatment of FMS were widely retrieved from Chinese Biomedical Databases (1979 - 2010), www. cnki. net (1979-2010), VIP China Scientific Journal Database (1989- 2010), Digital Periodicals on Wanfang Data (1998 - 2010), PubMed (1966-2010), etc. and by using key words of fibromyalgia syndrome and acupuncture. According to criterion of evidence-based medicine, the evidence from high to low quality levels was selected to answer corresponding clinical questions, and software RevMan 5.0 was used to analyze the final results. There has been no enough clinical evidence showing definite efficacy of acupuncture for FMS. However, a Level-A study (being in line with conditions of large sample, multi-centers, randomized controlled trails) and a level-C study (having control group, but without distinct randomizing method) showed respectively that acupuncture might be superior to Amitriptyline and Brufen in relieving FMS. Moreover, a piece of evidence that acupuncture combined with western medicine was superior to western medicine alone was allocated to a level-B (having correct randomizing method and control group). Finally, only a level-C evidence proved that laser irradiation on acupoint might be superior to traditional acupuncture in improving FMS. Acupuncture for FMS has a positive effect, and acupuncture combined with western medicine can strengthen the curative effect. However this conclusion should be proved further by randomized controlled double blind clinical trials with large samples.

Wang Q.,Tianjin University of Science and Technology | Jia Q.,Tianjin University of Science and Technology | Ma P.,Tianjin University
Journal of Chemical and Engineering Data | Year: 2012

A new universal method was proposed for the prediction of properties of organic compounds, such as critical properties, normal boiling point, and the enthalpy of vaporization. In this study, the positional distributive contribution method is further extended for the prediction of the acentric factor ω of a variety of pure organic compounds. Comparison results between experimental and calculated data indicate that the new model could provide very satisfactory results. The overall average absolute error for the ω prediction of 477 organic compounds is 0.0252 with 5.72 % mean absolute relative deviation, which is compared to 0.0569 and 14.58 % with the Constantinou and Gani method. Also, a good prediction of the proposed method shown in our previous works and this work suggests that it is possible to use the same universal formula to predict not only T c, P c, V c, Z c, T b, T m, and Δ vapH b but also ω of organic compounds, which further demonstrates the universality, stability, and accuracy of our proposed method. © 2011 American Chemical Society.

Shen Q.,Aberystwyth University | Zhao R.,Tianjin University
IEEE Transactions on Systems, Man, and Cybernetics Part A:Systems and Humans | Year: 2011

This paper presents an extension of the assumption-based truth maintenance system (ATMS), called credibilistic ATMS, which has the capability to cope with uncertain justifications and assumptions. Such justifications and assumptions are represented and dealt with in the framework of credibility theory. Important concepts in ATMS such as environments, labels, logical consequences, and consistency are redefined by the use of credibility measure. Based on these concepts, the label-updating procedure of the classical ATMS is extended, allowing effective computation of the membership function of any node within the network and that of its supporting environment. In addition, the contradictory environments can be captured with respect to their inconsistency degrees. This paper is compared to the most relevant existing research (i.e., ATMS using necessity as the truth value and ATMS using possibility as the truth value), demonstrating the significant improvements made. This paper also presents an illustrative application of credibilistic ATMS in supporting automated construction of domain models. © 2006 IEEE.

Wei H.-Y.,Tianjin University
Chemical Engineering Research and Design | Year: 2010

Scaling up a crystallization process often results in significant changes to crystal size distribution (CSD), purity and morphology, which are key determinants of product quality and has implications for downstream operations such as filtration. This unwelcome observation results from the interplay between hydrodynamics and crystallization kinetics that scale in different ways. Computer-aided tools, such as process system engineering (PSE) software and computational fluid dynamics (CFD) simulations, offer a means to understand these interactions within system constraints and to use the insight thus gained to guide scale-up strategies. This article outlines approaches to scaling up crystallizers and how to develop new processes, showing how numerical simulations and other software tools can be used to address typical issues arising in each case. © 2009 The Institution of Chemical Engineers.

Wei Y.Y.,Tianjin University
Zhongguo zhen jiu = Chinese acupuncture & moxibustion | Year: 2010

OBJECTIVE: To investigate the specificity of the acupoints and related factors on acupuncture effects. METHODS: The rat model of cerebral median artery occlusion (MCAO) was established with thread ligation according to Zea-Longa method. The acupoint group and the non-acupoint group were stimulated by acupuncture with 9 different parameters (marked group No. I - VI) combined by frequency (60 Hz, 120 Hz, 180 Hz) and time (5 s, 60 s, 180 s). The acupoint of "shuigou" (GV 26) was selected for the acupoint group, the fixed point which was at a distance of 10 mm from the iliac crest below the ribs in the affected side. The acupuncture effect was evaluated with the percentage of brain infarct area after TTC dyeing. RESULTS: (1) Acupoint groups could obviously reduce the brain infarction area in MCAO rats. Under 9 intervention parameters, acupoint groups had much more effectiveness tendency than that of the non-acupoint groups. (2) Acupoint group VI was the most effective in reducing the brain infarction area among 9 acupuncture parameter groups. CONCLUSION: (1) Acupoint has specificity effect on reduction of brain infarct area in MCAO rats. (2) Acupoint group VI (180 Hz; 5 s) could significantly reduce the percentage of cerebral infarction area by TTC dyeing.

Min F.,Zhangzhou Normal University | Hu Q.,Tianjin University | Zhu W.,Zhangzhou Normal University
International Journal of Approximate Reasoning | Year: 2014

Feature selection is an important preprocessing step in machine learning and data mining. In real-world applications, costs, including money, time and other resources, are required to acquire the features. In some cases, there is a test cost constraint due to limited resources. We shall deliberately select an informative and cheap feature subset for classification. This paper proposes the feature selection with test cost constraint problem for this issue. The new problem has a simple form while described as a constraint satisfaction problem (CSP). Backtracking is a general algorithm for CSP, and it is efficient in solving the new problem on medium-sized data. As the backtracking algorithm is not scalable to large datasets, a heuristic algorithm is also developed. Experimental results show that the heuristic algorithm can find the optimal solution in most cases. We also redefine some existing feature selection problems in rough sets, especially in decision-theoretic rough sets, from the viewpoint of CSP. These new definitions provide insight to some new research directions. © 2013 Elsevier Inc. All rights reserved.

Ke H.-W.,Tianjin University | Wei Z.-T.,Nankai University | Li X.-Q.,Nankai University
European Physical Journal C | Year: 2013

Assuming the newly observed Z c(3900) to be a molecular state of DD̄*(D*D̄), we calculate the partial widths of Zc(3900)→J/ψ+π; ψ′+π; η c+ρ and DD̄* within the light-front model (LFM). Z c(3900)→J/ψ+π is the channel by which Zc(3900) was observed, our calculation indicates that it is indeed one of the dominant modes whose width can be in the range of a few MeV depending on the model parameters. Similar to Zb and Zb′, Voloshin suggested that there should be a resonance Zc′ at 4030 MeV, which can be a molecular state of D*D̄*. Then we go on calculating its decay rates to all the aforementioned final states and the D*D̄* as well. It is found that if Zc(3900) is a molecular state of (Formula presented.), the partial width of Zc(3900) ̄ DD̄* is rather small, but the rate of Zc(3900)→ψ(2s)π is even larger than Zc(3900)→J/ψπ. The implications are discussed and it is indicated that with the luminosity of BES and BELLE, the experiments may finally determine if Zc(3900) is a molecular state or a tetraquark. © 2013 Springer-Verlag Berlin Heidelberg and Società Italiana di Fisica.

This paper investigates the probability density evolution process of a van der Pol-Duffing oscillator under Gaussian white noise. A path integration method is employed with the Gauss–Legendre integration scheme. In the path integration method, the short-time Gaussian approximation scheme is used for computing the one-step transition probability density. Two cases are considered with slight nonlinearity or strong nonlinearity in displacement. The stationary and non-stationary responses of the oscillator are studied. Compared with the simulation result, the path integration method can present a satisfactory probability density function (PDF) solution for each case. Different probability density evolution processes are observed correspondingly. In the case of slight nonlinearity, the PDF undergoes a clockwise motion around the origin. The peak region gradually expands and the PDF eventually forms a circle. By contrast, the strong nonlinearity drives the oscillator to oscillate around the limit cycle. In such a case, the PDF rapidly forms a circle. The circle keeps its shape and develops until the oscillator becomes stationary. More complicated phenomena can be studied by the adopted path integration method. © 2016 Springer Science+Business Media Dordrecht

Li B.,Tsinghua University | Han C.,Tsinghua University | He Y.-B.,Tsinghua University | Yang C.,Tsinghua University | And 4 more authors.
Energy and Environmental Science | Year: 2012

The Li 4Ti 5O 12/C composite with lump morphology and excellent rate performance are synthesized using a facile hydrothermal method followed by a low temperature heat treatment. In the hydrothermal process, the introduction of cetyltrimethylammonium bromide (CTAB) as a surfactant significantly improves the rate performance of Li 4Ti 5O 12/C composite as anode material for lithium ion battery (LIB). The specific capacities of the obtained composite at charge and discharge rates of 0.1, 1, 5, 10 and 20 C are 176, 163, 156, 151 and 136 mA h g -1, respectively, which is apparently larger than those of the Li 4Ti 5O 12/C free from CTAB in the preparation. The Li 4Ti 5O 12/C prepared in presence of CTAB also shows excellent cycling performance at high rate, which is attributed to its larger diffusion coefficient of lithium ion (6.82 × 10 -12 cm 2 s -1) and smaller charge-transfer resistance (R ct) (19.2 Ω) than those of the composite (1.22 × 10 -13 cm 2 s -1 and 50.2 Ω) free from CTAB in the preparation. The Li 4Ti 5O 12 particles obtained in presence of CTAB are coated uniformly by a thin carbon layer with a thickness of ∼1 nm, whereas the Li 4Ti 5O 12 particles obtained in absence of CTAB are covered by relatively thick surface layers with a thickness of ∼2.5 nm, which is too thick, blocks the lithium ion diffusion and leads to low ionic conductivity. © 2012 The Royal Society of Chemistry.

Zhang B.,Nankai University | Qin X.,Tianjin University | Li G.R.,Nankai University | Gao X.P.,Nankai University
Energy and Environmental Science | Year: 2010

To enhance the long stability of sulfur cathode for a high energy lithium-sulfur battery system, a sulfur-carbon sphere composite was prepared by encapsulating sulfur into micropores of carbon spheres by thermal treatment of a mixture of sublimed sulfur and carbon spheres. The elemental sulfur exists as a highly dispersed state inside the micropores of carbon spheres with a large surface area and a narrow pore distribution, based on the analyses of the X-ray powder diffraction (XRD), transmission electron microscopy (TEM), Brunauer-Emmett-Teller (BET), thermogravimetry (TG) and local element line-scanning. It is demonstrated from galvanostatic discharge-charge process, cyclic voltammetry (CV) and electrochemical impedance spectra (EIS) that the sulfur-carbon sphere composite has a large reversible capacity and an excellent high rate discharge capability as cathode materials. In particular, the sulfur-carbon sphere composite with 42 wt% sulfur presents a long electrochemical stability up to 500 cycles, based on the constrained electrochemical reaction inside the narrow micropores of carbon spheres due to strong adsorption. Therefore, the electrochemical reaction constrained inside the micropores proposed here would be the dominant factor for the enhanced long stability of the sulfur cathode. The knowledge acquired in this study is important not only for the design of efficient new electrode materials, but also for understanding the effect of the micropores on the electrochemical cycle stability. © 2010 The Royal Society of Chemistry.

Liu Y.,Tianjin University | Ye H.,Chinese Institute of Urban Environment
Journal of Cleaner Production | Year: 2012

Employing an adaptive agent-based modeling approach, the present study explored the evolvement of firms' environmental behavior and influencing factors. Using empirical data from 167 firms in China, the simulation results revealed that firms' environmental behavior followed this evolvement path: defensive behavior, preventive behavior, and enthusiastic behavior. Computational experiments indicated that with increased financial ability and level of environmental preparedness, the number of firms in all three categories of environmental behavior increased and so did their profits. With increased public pressure, the number of firms with defensive environmental behavior and their profits decreased, but the number of firms with preventive and enthusiastic environmental behavior and their profits increased. On the other hand, when managers' education level increased, the number of firms with defensive behavior deceased, but their profits increased slightly, though the number of firms with preventive and enthusiastic behavior and their profits increased sharply. In addition, with the increased regulation level, the number of firms with a different category of environmental behavior and their profits decreased. Finally, with increased financial subsidy and market share, the number of firms with different behavior and their profits were modified slightly. © 2012 Elsevier Ltd. All rights reserved.

Huang Y.,Tianjin University
Cold Regions Science and Technology | Year: 2010

From 2007 to 2008, a series of model tests were performed to observe the ice failure before wide conical structures. The variable testing parameters include the water line diameter of the model cone and ice speed. When D/ h> 25, the failures of ice wedges around the cone start to behave nonsimultaneously in these tests. The rubble piece size and the ride-up height were found to have linear relationships with the ratio of D/. h in the tests. Several independent zones of bending were found in the nonsimultaneous failure process of ice. With the increasing of the ratio of D/. h and the number of independent zones, the total ice force was found being reduced by degrees. © 2010 Elsevier B.V.

Zhu H.T.,Tianjin University
Nonlinear Dynamics | Year: 2012

This paper investigates the nonzero mean probability density function (PDF) of nonlinear oscillators under additive Poisson impulses. The PDF is governed by the generalized Fokker-Planck- Kolmogorov (FPK) equation which is also called the Kolmogorov-Feller (KF) equation. An exponentialpolynomial closure (EPC) method is adopted to solve the equation. Five examples are considered in numerical analysis to show the effectiveness of the EPC method. The nonzero mean response of nonlinear oscillators is formulated due to either nonlinearity type or nonzero mean amplitude of Poisson impulses. The analysis shows that the PDFs obtained with the EPC method agree with the simulated results when the polynomial order is 4 or 6. This agreement is also observed in the tail regions of the obtained PDFs. The comparison further shows that the nonzero mean PDF of displacement is nonsymmetrically distributed. Comparatively, the PDF of velocity still has a symmetrical distribution pattern when the nonlinearity only exists in displacement. © Springer Science+Business Media B.V. 2012.

Yao H.K.,Tianjin University
Zhong yao cai = Zhongyaocai = Journal of Chinese medicinal materials | Year: 2010

To study the chemical constituents of Wikstroemia indica. The constituents were isolated and purified by silica gel chromatography repeatedly, and the structures were determined by spectral data and chemical envidance. Six compounds were isolated from its petroleum ether, dichloromethane, acetone and methanol extracts and identified as: daphnoretin-7-O-beta-D-glucoside (1), aloe-emodin (2), kaempferol (3), 29-nonacosanolide (4), 1-octadecanol (5), beta-sitosterol (6). Compounds 2, 4, 5 are isolated from this plant for the first time.

Jiao K.,University of Waterloo | Li X.,University of Waterloo | Li X.,Tianjin University
Progress in Energy and Combustion Science | Year: 2011

Polymer electrolyte membrane fuel cell (PEMFC) has been recognized as a promising zero-emission power source for portable, mobile and stationary applications. To simultaneously ensure high membrane proton conductivity and sufficient reactant delivery to reaction sites, water management has become one of the most important issues for PEMFC commercialization, and proper water management requires good understanding of water transport in different components of PEMFC. In this paper, previous researches related to water transport in PEMFC are comprehensively reviewed. The state and transport mechanism of water in different components are elaborated in detail. Based on the literature review, it is found that experimental techniques have been developed to predict distributions of water, gas species, temperature and other parameters in PEMFC. However, difficulties still remain for simultaneous measurements of multiple parameters, and the cell and system design modifications required by measurements need to be minimized. Previous modeling work on water transport in PEMFC involves developing rule-based and first-principle-based models, and first-principle-based models involve multi-scale methods from atomistic to full cell levels. Different models have been adopted for different purposes and they all together can provide a comprehensive view of water transport in PEMFC. With the development of computational power, application of lower length scale methods to higher length scales for more accurate and comprehensive results is feasible in the future. Researches related to cold start (startup from subzero temperatures) and high temperature PEMFC (HT-PEMFC) (operating at the temperatures higher than 100 °C) are also reviewed. Ice formation that hinders reactant delivery and damages cell materials is the major issue for PEMFC cold start, and enhancing water absorption by membrane electrolyte and external heating have been identified as the most effective ways to reduce ice formation and accelerate temperature increment. HT-PEMFC that can operate without liquid water formation and membrane hydration greatly simplifies water management strategy, and promising performance of HT-PEMFC has been demonstrated. © 2010 Elsevier Ltd. All rights reserved.

Yan L.,Jiangxi Science and Technology Normal University | Chang P.R.,Agriculture and Agri Food Canada | Zheng P.,Jiangxi Science and Technology Normal University | Ma X.,Tianjin University
Carbohydrate Polymers | Year: 2012

The hydrophobicity of carbon nanotubes (CNTs) limits their extensive application. The hydrophilicity and biocompatibility of CNTs can be improved by modifying them with biopolymers. As a natural biopolymer, guar gum (GG) was covalently grafted on the surfaces of multiwall carbon nanotube (MWCNT) to obtain GG-MWCNT composite. Then iron oxide nanoparticles were synthesized on the GG-MWCNT to prepare the magnetic GG-MWCNT-Fe 3O 4. The obtained nanocomposites were characterized by Fourier transform infrared spectroscopy, thermogravimetric analysis, transmission electron microscopy, ultraviolet-visible (UV-vis) spectroscopy and X-ray diffraction. GG-MWCNT was composed of about 21.6 wt% GG components, which enhanced the dispersion of GG-MWCNT in aqueous solution and also acted as a template for growth of iron oxide nanoparticles. GG-MWCNT-Fe 3O 4 exhibited superparamagnetic with a saturation magnetization (13.3 emu g -1), and good adsorption on neutral red and methylene blue. GG-MWCNT-Fe 3O 4 could be easily separated from the aqueous solution in a magnetic field. © 2011 Elsevier Ltd. All rights reserved.

Zhao J.X.,Tianjin University
Computers and Mathematics with Applications | Year: 2014

We consider a class of complementarity problems involving functions which are nonlinear. In this paper we reformulate this nonlinear complementarity problem as a system of absolute value equations (which is nonsmooth). Then we propose a fixed-point method to solve this nonsmooth system. We prove that the proposed method is globally linearly convergent under a mild condition. The proposed method is greatly effective not only for small and medium size problems, but also for large and super-large scale problems. Especially, our method can efficiently solve super-large scale problems, with a million variables, in a few tens of minutes on a PC. © 2014 Elsevier Ltd. All rights reserved.

Song Y.-L.,Tianjin University
Chinese Physics B | Year: 2014

The effect of noise frequency on the FitzHugh - Nagumo neuron is investigated by the use of the harmonic velocity noise, which has a direct frequency parameter and no zero frequency part of the power spectrum. It is shown that the neuron has the resonance characteristic strongly responding to the noise with a certain frequency at fixed power, and there is double coherence resonance related to the frequency and the intensity. If the harmonic velocity noise lacks low frequency ingredients, there is no synchronization between the frequency of the neuron and that of the noise. Thus the low frequency part of the noise plays an important role in creating the synchronization. © 2014 Chinese Physical Society and IOP Publishing Ltd.

Bai N.,University of Central Florida | Bai N.,Infinera Corporation | Li G.,Infinera Corporation | Li G.,Tianjin University
Optics Express | Year: 2014

The equalizer tap length requirement is investigated analytically and numerically for differential modal group delay (DMGD) compensated fiber link with weakly random mode coupling. Each span of the DMGD compensated link comprises multiple pairs of fibers which have opposite signs of DMGD. The result reveals that under weak random mode coupling, the required tap length of the equalizer is proportional to modal group delay of a single DMGD compensated pair, instead of the total modal group delay (MGD) of the entire link. By using small DMGD compensation step sizes, the required tap length (RTL) can be potentially reduced by 2 orders of magnitude. © 2014 Optical Society of America.

Liu W.-H.,Tianjin University | Xu X.-C.,Huazhong University of Science and Technology | Kouhpaenejad A.,University of Nevada, Las Vegas
Computers and Industrial Engineering | Year: 2013

In the design of the revenue-sharing contract, it is critical to determine a rational revenue-sharing coefficient which affects the coordination and stability of supply chain. In order to improve the existing system, one should take into account that the current revenue-sharing coefficient study only figures out its range rather than the specific value. This paper investigates the fairest revenue-sharing coefficient when the logistics service integrator and the functional logistics service provider implement revenue-sharing contract under stochastic demand condition; by focusing on a two-echelon logistics service supply chain composed of a logistics service integrator and a functional logistics service provider. Taken into consideration the non-storage property of logistics service supply chain, this paper establishes a Stackelberg game model by giving priority to the logistics service integrator. The interval of the revenue-sharing coefficient is obtained by revenue-sharing contract mechanism. Based on the principle of profit distribution equity, a fair entropy function is introduced and a non-linear programming model for solving the fairest revenue-sharing coefficient is established. Furthermore, this method is extended to a three-echelon logistics service supply chain composed of a logistics service integrator, a functional logistics service provider, and a logistics subcontractor. It is assumed that the logistics subcontractor fully commits to the logistics capacity of the functional logistics service provider and consequently a non-linear programming model is constructed to solve the fairest revenue-sharing coefficient of a three-echelon logistics service supply chain under stochastic demand condition. The results exemplifies that the proposed method can find out the fairest revenue-sharing coefficient in a two-echelon and a three-echelon logistics service supply chain, which provides an approach to revenue-sharing contract study. © 2013 Elsevier Ltd. All rights reserved.

Wang M.,Tianjin University
Biotechnology letters | Year: 2012

Acetoin is widely used in food and other industries. A bdhA and acoA double-knockout strain of Bacillus subtilis produced acetoin at 0.72 mol/mol, a 16.4 % increased compared to the wild type. Subsequent overexpression of the alsSD operon enhanced the acetolactate synthase activity by 52 and 66 % in growth and stationary phases, respectively. However, deletion of pta gene caused little increase of acetoin production. For acetoin production by the final engineered strain, BSUW06, acetoin productivity was improved from 0.087 g/l h, using M9 medium plus 30 g glucose/l under micro-aerobic conditions, to 0.273 g/h l using LB medium plus 50 g glucose/l under aerobic conditions. In fermentor culture, BSUW06 produced acetoin up to 20 g/l.

Muramulla S.,University of Texas at San Antonio | Ma J.-A.,Tianjin University | Zhao J.C.-G.,University of Texas at San Antonio
Advanced Synthesis and Catalysis | Year: 2013

Modularly designed organocatalysts (MDOs) formed in situ from the self-assembly of primary α-amino acids and Cinchona alkaloid thioureas were found to be excellent catalysts for the stereoselective Michael addition of enolizable ketones and aldehydes to maleimides. Using an MDO formed from quinidine thiourea and L-2-chlorophenylglycine, the corresponding Michael addition products, 3-substituted succinimides, may be obtained in excellent yields and high enantio- and diastereoselectivities. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Lin J.,Rice University | Zhang C.,Rice University | Zhang C.,Tianjin University | Yan Z.,Rice University | And 5 more authors.
Nano Letters | Year: 2013

In this research, 3-dimensional (3D) graphene/carbon nanotube carpets (G/CNTCs)-based microsupercapacitors (G/CNTCs-MCs) were fabricated in situ on nickel electrodes. The G/CNTCs-MCs show impedance phase angle of -81.5 at a frequency of 120 Hz, comparable to commercial aluminum electrolytic capacitors (AECs) for alternating current (ac) line filtering applications. In addition, G/CNTCs-MCs deliver a high volumetric energy density of 2.42 mWh/cm3 in the ionic liquid, more than 2 orders of magnitude higher than that of AECs. The ultrahigh rate capability of 400 V/s enables the microdevices to demonstrate a maximum power density of 115 W/cm3 in aqueous electrolyte. The high-performance electrochemical properties of G/CNTCs-MCs can provide more compact ac filtering units and discrete power sources in future electronic devices. These elevated electrical features are likely enabled by the seamless nanotube/graphene junctions at the interface of the differing carbon allotropic forms. © 2012 American Chemical Society.

Zhang B.,University of Pennsylvania | Zhang B.,Tianjin University | Jung Y.,University of Pennsylvania | Chung H.-S.,University of Pennsylvania | And 2 more authors.
Nano Letters | Year: 2010

The unique properties of nanostructured materials enable their transformation into complex, kinetically controlled morphologies that cannot be obtained during their growth. Solution-phase cation-exchange reactions can transform sub-10 nm nanocrystals/nanorods into varying compositions and superlattice structures; however, because of their small size, cation-exchange reaction rates are extremely fast, which limits control over the transformed products and possibilities for obtaining new morphologies. Nanowires are routinely synthesized via gas-phase reactions with 5-200 nm diameters, and their large aspect ratios allow them to be electrically addressed individually. To realize their full potential, it is desirable to develop techniques that can transform nanowires into tunable but precisely controlled morphologies, especially in the gas-phase, to be compatible with nanowire growth schemes. We report transformation of single-crystalline cadmium sulfide nanowires into composition-controlled ZnxCd(1-X)S nanowires, core-shell heterostructures, metal-semiconductor superlattices (Zn-ZnrCd (1-x)S), single-crystalline ZnS nanotubes, and eventually metallic Zn nanowires by utilizing size-dependent cation-exchange reaction along with temperature and gas-phase reactant delivery control. This versatile synthetic ability to transform nanowires offers new opportunities to study size-dependent phenomena at the nanoscale and tune their chemical/physical properties to design reconfigurable circuits. © 2010 American Chemical Society.

Zhang J.,University of Technology, Sydney | Huang M.L.,University of Technology, Sydney | Huang M.L.,Tianjin University
Concurrency Computation | Year: 2016

In this paper, we extended our density model to BigData analysis and visualization. BigData, which contains images, videos, texts, audio files and other forms of data collected from multiple datasets, is difficult to process and visualize using traditional database management and visualization tools. The challenges are in representing multiple datasets and illustrating and visualizing data patterns to meet business, government and organization needs. We have established the 5Ws density model which uses the 5Ws dimensions for BigData analysis and visualization. The 5Ws dimensions are what the data contain, why the data were transferred, where the data came from, when the data occurred, who received the data and how the data were transferred. According to the network log dataset, an example of BigData, each data incident can be classified into these 5Ws dimensions. The network log dataset ISCX2012 is tested throughout our model. This new model not only classifies network attributes and patterns but also establishes density patterns that provide more analytical features for BigData analysis and visualization. The experimental result shows that this new model with clustered visualization can be efficiently used for BigData analysis and network intrusion detection. Concurrency and Computation: Practice and Experience, 2014. Copyright © 2014 John Wiley & Sons, Ltd.

Liu H.,Tianjin University
Journal of Marine Science and Application | Year: 2012

Experimental and theoretical studies of drag embedment plate anchors recently carried out in Tianjin University are summarized in this research paper, which involve a series of important topics relevant to the study of drag anchors. The techniques for measuring the trajectory and movement direction of drag anchors in soils, the techniques for measuring the moving embedment point and reverse catenary shape of the embedded drag line, the penetration mechanism and kinematic behavior of drag anchors, the ultimate embedment depth of drag anchors, the movement direction of the anchor with an arbitrary fluke section, the reverse catenary properties of the embedded drag line, the interactional properties between drag anchor and installation line, the kinematic model of drag anchors in seabed soils, and the analytical method for predicting the anchor trajectory in soils will all be examined. The present work remarkably reduces the uncertainties in design and analysis of drag embedment plate anchors, and is beneficial to improving the application of this new type of drag anchor in offshore engineering. © 2012 Harbin Engineering University and Springer-Verlag Berlin Heidelberg.

Peng X.-L.,University of Western Australia | Hao H.,University of Western Australia | Li Z.-X.,Tianjin University | Fan K.-Q.,Wuyi University
Engineering Structures | Year: 2013

Free span along subsea pipelines is a general problem both in pipeline design phase and during operation of pipelines. Traditionally, subsea pipeline system is inspected over the entire pipeline length with inspection tools, such as side-scan sonar and video/camera carried by remote controlled vehicle. The obvious disadvantage is that this kind of inspection can only be carried out at scheduled intervals. In a previous study [1], a damage indicator, WPECR, was proposed based on wavelet packet transform analysis to identify free-spanning damage along subsea pipelines. The reliability and efficiency of the proposed damage indicator is proven with numerical simulated vibration data of pipeline under ambient sea wave forces. To further verify the proposed method, in this paper, two scaled pipe models with different boundary conditions were designed and tested subject to random wave forces in a large wave tank. Waterproof accelerometers were used to collect pipeline responses which were subsequently analyzed for pipeline condition monitoring. The results show that using output-only dynamic responses of pipeline subject to random ambient wave excitations can accurately identify free span locations and length. With a vibration based method, real time monitoring of scouring damage to subsea pipelines is achievable so that any free span longer than allowable span length can be detected at an early stage. © 2012 Elsevier Ltd.

Xue J.,Tianjin University of Technology | Wang X.,Tianjin University of Technology | Qi G.,General Motors | Wang J.,Tianjin University of Technology | And 3 more authors.
Journal of Catalysis | Year: 2013

To investigate the active Cu sites in the selective catalytic reduction of NO by NH3 (NH3 SCR) over Cu/SAPO-34 catalysts, a series of samples containing different Cu loadings has been prepared by an ion-exchange process. A combination of H2 TPR and EPR techniques was applied to identify and quantify the isolated Cu2+ sites. The trend of the isolated Cu2+ ions in the samples estimated by EPR is similar to that from TPR results and was found to be proportional to the NH3 SCR reaction rates. The turnover frequency (TOF) calculated based on the number of isolated Cu2+ ions on samples with varying Cu loadings showed a constant value at the same temperature. Thus, we conclude that the isolated Cu2+ species associated with the six-ring window and displaced into the ellipsoidal cavity of SAPO-34 (Site (I)) are the active sites for the NH3 SCR reaction in the temperature range 100-200 °C. © 2012 Elsevier Inc. All rights reserved.

Li S.,Northeastern University China | Dai J.S.,Tianjin University | Dai J.S.,Kings College London
Journal of Mechanisms and Robotics | Year: 2012

This paper presents a new way of structure composition of single-driven metamorphic mechanisms to develop a systematic and modularized structure synthesis methodology of metamorphic mechanisms based on augmented Assur groups (AAGs). Planar metamorphic mechanisms can hence be constructed based on the developed AAGs by applying the structure composition rule of general planar mechanisms formed by Assur groups (AGs). First, the one-mobility AAGs are introduced based on class II and class III AGs; the structure formulation and composition methodology of planar metamorphic mechanisms are then proposed based on the AAGs, and the basic problems including mobility and synthesis of constrained metamorphic working mobility-configuration are investigated. This leads to the investigation of the degenerated equivalent AGs of AAGs in the metamorphic process and the corresponding kinematic characteristics, providing references for kinematic synthesis of metamorphic mechanisms. Further, a typical spatial metamorphic group is introduced based on the concept of AAGs, and the structure formation and composition of spatial metamorphic mechanisms are presented. Examples show that both planar and spatial metamorphic mechanisms can be constructed by utilizing the one-mobility blocks extended from the AGs. © 2012 American Society of Mechanical Engineers.

Dai J.S.,Tianjin University | Dai J.S.,Kings College London
Journal of Mechanisms and Robotics | Year: 2012

Rigid body displacement can be presented with Chasles' motion by rotating about an axis and translating along the axis. This motion can be implemented by a finite displacement screw operator in the form of either a 3 × 3 dual-number matrix or a 6 × 6 matrix that is executed with rotation and translation as an adjoint action of the Lie group. This paper investigates characteristics of this finite displacement screw matrix and decomposes the secondary part that is the off diagonal part of the matrix into the part of an equivalent translation due to the effect of off-setting the rotation axis and the part of an axial translation. The paper hence presents for the first time the axial translation matrix and reveals its property, leading to discovery of new results and new formulae. The analysis further reveals two new traces of the matrix and presents the relationship between the finite displacement screw matrix and the instantaneous screw, leading to the understanding of Chasles' motion embedded in a rigid body displacement. An algebraic and geometrical interpretation of the finite displacementscrew matrix is thus given, presenting an intrinsic property of the matrix in relation to the finite displacement screw. The paper ends with a case study to verify the theory and illustrate the principle. © 2012 American Society of Mechanical Engineers.

Men C.,Tianjin University
Chaos (Woodbury, N.Y.) | Year: 2012

We investigate the propagation of spiking regularity in noisy feedforward networks (FFNs) based on FitzHugh-Nagumo neuron model systematically. It is found that noise could modulate the transmission of firing rate and spiking regularity. Noise-induced synchronization and synfire-enhanced coherence resonance are also observed when signals propagate in noisy multilayer networks. It is interesting that double coherence resonance (DCR) with the combination of synaptic input correlation and noise intensity is finally attained after the processing layer by layer in FFNs. Furthermore, inhibitory connections also play essential roles in shaping DCR phenomena. Several properties of the neuronal network such as noise intensity, correlation of synaptic inputs, and inhibitory connections can serve as control parameters in modulating both rate coding and the order of temporal coding.

Liu Y.,Tianjin University
Journal of Cleaner Production | Year: 2014

Industrial firms are central to the effort to grapple with emission of greenhouse gases due to large material flows they process. Thus, employing system dynamics approach, the present study explored influencing factors of industrial firms' carbon footprint. Using empirical data from selected firms in China, simulation results revealed that price of raw material; governmental subsidy and pressure from international rules, as well as firm's awareness of social responsibility have slightly affected firms' carbon emissions. On the contrary, some factors have obvious effects on firms' carbon footprint including governmental regulation, awareness of consumer, company size, the ratio of low carbon package and recycling. © 2014 Elsevier Ltd. All rights reserved.

In this paper, we consider the Cauchy problem of a nonlinear Schrödinger system. Through establishing a sharp weighted vector-valued Gagliardo-Nirenberg's inequality, we find that the best constant in this inequality can be regarded as the criterion of blowup and global existence of the solutions when p=4/N. And we prove that the solutions of this system will always exist globally if p<4/N. The sharp thresholds for blowup and global existence are also obtained when 4/N≤p<4/ (N-2)+. © 2010 American Institute of Physics.

Liu A.-A.,Tianjin University | Li K.,Microsoft | Kanade T.,Carnegie Mellon University
IEEE Transactions on Medical Imaging | Year: 2012

We propose a semi-Markov model trained in a max-margin learning framework for mitosis event segmentation in large-scale time-lapse phase contrast microscopy image sequences of stem cell populations. Our method consists of three steps. First, we apply a constrained optimization based microscopy image segmentation method that exploits phase contrast optics to extract candidate subsequences in the input image sequence that contains mitosis events. Then, we apply a max-margin hidden conditional random field (MM-HCRF) classifier learned from human-annotated mitotic and nonmitotic sequences to classify each candidate subsequence as a mitosis or not. Finally, a max-margin semi-Markov model (MM-SMM) trained on manually-segmented mitotic sequences is utilized to reinforce the mitosis classification results, and to further segment each mitosis into four predefined temporal stages. The proposed method outperforms the event-detection CRF model recently reported by Huh as well as several other competing methods in very challenging image sequences of multipolar-shaped C3H10T1/2 mesenchymal stem cells. For mitosis detection, an overall precision of 95.8% and a recall of 88.1% were achieved. For mitosis segmentation, the mean and standard deviation for the localization errors of the start and end points of all mitosis stages were well below 1 and 2 frames, respectively. In particular, an overall temporal location error of 0.73 \pm 1.29 frames was achieved for locating daughter cell birth events. © 2011 IEEE.

Wang X.,Institute for Infocomm Research | Nie W.,Tianjin University
Neurocomputing | Year: 2015

In recent years, we have witnessed a flourishing of 3D object modelling. Efficient and effective 3D model retrieval algorithms are high desired and attracted intensive research attentions. In this work, we propose a view-based 3D model retrieval algorithm based on weighted locality-constrained group sparse coding. Representative views are first selected by clustering and the corresponding weights are provided by considering the relationship among these views. By grouping the views from 3D models, a locality-constrained group sparse coding method is employed to find the reconstruction residual for each query view. The distance between query model and candidate model is taken as the weighted sum of residual. The query model is matched to the model which can best reconstruct the query model. Experimental comparisons have been conducted on the ETH 3D model dataset, and the results have demonstrated the effectiveness of the proposed method. © 2014 Elsevier B.V.

Zhang C.-T.,Tianjin University
Journal of the American Society for Information Science and Technology | Year: 2010

Of h-type indices available now, the g-index is an important one in that it not only keeps some advantages of the h-index but also counts citations from highly cited artlcles. However, the g-index has a drawback that one has to add fictitious articles with zero citation to calculate this index in some important cases. Based on an alternative definition without introducing fictitious articles, an analytical method has been proposed to calculate the g-index based approximately on the h-index and the e-index. If citations for a scientist are ranked by a power law, it is shown that the g-index can be calculated accurately by the h-index, the e-index, and the power parameter. The relationship of the h-, g-, and e-indices presented here shows that the g-index contains the citation information from the h-index, the e-index, and some papers beyond the h-core. © 2009 ASIS&T.

Li X.,CAS Xian Institute of Optics and Precision Mechanic | Pang Y.,Tianjin University
IEEE Transactions on Knowledge and Data Engineering | Year: 2010

In this paper, we propose a deterministic column-based matrix decomposition method. Conventional column-based matrix decomposition (CX) computes the columns by randomly sampling columns of the data matrix. Instead, the newly proposed method (termed as CX-D) selects columns in a deterministic manner, which well approximates singular value decomposition. The experimental results well demonstrate the power and the advantages of the proposed method upon three real-world data sets. © 2006 IEEE.

Chen J.,Tianjin University
The Scientific World Journal | Year: 2014

Human gait identification aims to identify people by a sequence of walking images. Comparing with fingerprint or iris based identification, the most important advantage of gait identification is that it can be done at a distance. In this paper, silhouette correlation analysis based human identification approach is proposed. By background subtracting algorithm, the moving silhouette figure can be extracted from the walking images sequence. Every pixel in the silhouette has three dimensions: horizontal axis (x), vertical axis (y), and temporal axis (t). By moving every pixel in the silhouette image along these three dimensions, we can get a new silhouette. The correlation result between the original silhouette and the new one can be used as the raw feature of human gait. Discrete Fourier transform is used to extract features from this correlation result. Then, these features are normalized to minimize the affection of noise. Primary component analysis method is used to reduce the features' dimensions. Experiment based on CASIA database shows that this method has an encouraging recognition performance. © 2014 Jinyan Chen.

Hu Q.,Tianjin University | Zhang L.,Hong Kong Polytechnic University | An S.,Northeastern University China | Zhang D.,Hong Kong Polytechnic University | Yu D.,Harbin Institute of Technology
IEEE Transactions on Fuzzy Systems | Year: 2012

Rough sets, especially fuzzy rough sets, are supposedly a powerful mathematical tool to deal with uncertainty in data analysis. This theory has been applied to feature selection, dimensionality reduction, and rule learning. However, it is pointed out that the classical model of fuzzy rough sets is sensitive to noisy information, which is considered as a main source of uncertainty in applications. This disadvantage limits the applicability of fuzzy rough sets. In this paper, we reveal why the classical fuzzy rough set model is sensitive to noise and how noisy samples impose influence on fuzzy rough computation. Based on this discussion, we study the properties of some current fuzzy rough models in dealing with noisy data and introduce several new robust models. The properties of the proposed models are also discussed. Finally, a robust classification algorithm is designed based on fuzzy lower approximations. Some numerical experiments are given to illustrate the effectiveness of the models. The classifiers that are developed with the proposed models achieve good generalization performance. © 1993-2012 IEEE.

Pang Y.,Tianjin University | Yuan Y.,Aston University
Neurocomputing | Year: 2010

Graph embedding is a general framework for subspace learning. However, because of the well-known outlier-sensitiveness disadvantage of the L2-norm, conventional graph embedding is not robust to outliers which occur in many practical applications. In this paper, an improved graph embedding algorithm (termed LPP-L1) is proposed by replacing L2-norm with L1-norm. In addition to its robustness property, LPP-L1 avoids small sample size problem. Experimental results on both synthetic and real-world data demonstrate these advantages. © 2009 Elsevier B.V. All rights reserved.

Wang H.,Purdue University | Chen Q.,Purdue University | Chen Q.,Tianjin University
Energy and Buildings | Year: 2012

Prediction of single-sided natural ventilation is difficult due to the bi-directional flow at the opening and the complex flow around buildings. A new empirical model was developed that can predict the mean ventilation rate and fluctuating ventilation rate due to the pulsating flow and eddy penetration of single-sided, wind-driven natural ventilation in buildings. The governing equation is based on the non-uniform pressure distribution along the opening height. The new model shows that the ventilation rate and wind velocity are linearly correlated. This investigation studied the eddy penetration effect in the frequency domain based on fast Fourier transform. Large eddy simulation (LES) and experimental data were used to validate the new empirical model. The model has also been used to analyze the influence of the opening geometry and elevation on the ventilation rate. © 2012 Elsevier B.V. All rights reserved.

Kang X.-D.,Tianjin University
Journal of Railway Engineering Society | Year: 2013

Research purposes: As the capital-intensive projects, the intercity railway project require huge amounts of investment in the construction period. How to broaden the financing way for the intercity railway, how to revitalize the huge stock of assets and how to realize preserving and increasing the value of the assets are crucial to the rapid and sustainable development of the intercity railway. So exploring the financing model for the intercity railway has great significance. Research conclusions: In combination with the characteristics of intercity railway, in this paper it is proposed that the financing model for intercity railway should be led by the government, along with using the market mechanisms and diversified financing methods and getting the support of the bank loans. (1) The financing model of land and property developments is the most effective way to make the public benefits of transport back to the construction of urban rail transit. (2) The local government bond is a good financing source for the infrastructure funding by the government. (3) The BT project financing is available for the financing for the non-operating infrastructure projects. (4) The medium-term note is the most potential financing way for intercity railway because it has the less restrictions compared with local bonds and corporate bonds. (5) The financing models presented in this paper can provide the reference to the financing for intercity railway, suburb railway, urban rail transit and other area.

Pang Y.,Tianjin University | Yuan Y.,CAS Xian Institute of Optics and Precision Mechanic | Wang K.,Nokia Inc.
Neurocomputing | Year: 2012

Common Spatial Pattern (CSP) is one of the most widespread methods for Brain-Computer Interfaces (BCI), which is capable of enhancing the separability of the brain signals such as multi-channel electroencephalogram (EEG). CSP attempts to strengthen the separability by maximizing the variance of the spatially filtered signal of one class while minimizing it for another class. A straightforward way to improve the CSP is to employ the Fisher-Rao linear discriminant analysis (FLDA). But for the two-class scenario in BCI, FLDA merely result in as small as one filter. Experimental results have shown that the number of spatial filter is too small to achieve satisfying classification accuracy. Therefore, more than one filter is expected to get better performance. To deal with this difficulty, in this paper we propose to divide each class into many sub-classes (clusters) and formulate the problem in a re-designed graph embedding framework where the vertexes are cluster centers. We also reformulate the traditional FLDA in our graph embedding framework, which helps developing and understanding the proposed method. Experimental results demonstrate the advantages of the proposed method. © 2011 Elsevier B.V.

Deng S.,Shanghai JiaoTong University | Deng S.,Tianjin University | Wang R.Z.,Shanghai JiaoTong University | Dai Y.J.,Shanghai JiaoTong University
Energy | Year: 2014

NZEB (Net zero energy building) is regarded as an integrated solution to address problems of energy-saving, environmental protection, and CO2 emission reduction in the building section. NZEB could be even possible with electricity production if enough renewable energy could be used. Moreover, various building-service systems with renewable energy sources have been widely considered for potential applications in NZEB. All of these new features extend the technical boundary of the conventional energy-efficient buildings, attach a more profound implication to the sustainable development of building technology, and therefore pose a challenge to evaluation works on NZEB performance.This paper presents a guided tour on NZEB evaluation through literature-research. An overview about definitions and energy-efficient measures of NZEB is presented so that the research object and technology boundary can be clarified for NZEB evaluation. Then, a summary of widely-used research method, tool and performance indicator in evaluation is provided for the methodology part. This part also includes a discussion on the application of LCA (life cycle assessment) in NZEB evaluation and LCA's role in promoting a well-defined NZEB. Finally, potential progress in NZEB evaluation with possible development trends is highlighted in terms of energy storage, load match and smart grid. © 2014 Elsevier Ltd.

Li X.,CAS Xian Institute of Optics and Precision Mechanic | Pang Y.,Tianjin University | Yuan Y.,Aston University
IEEE Transactions on Systems, Man, and Cybernetics, Part B: Cybernetics | Year: 2010

In this paper, we first present a simple but effective L1-norm-based two-dimensional principal component analysis (2DPCA). Traditional L2-norm-based least squares criterion is sensitive to outliers, while the newly proposed L1-norm 2DPCA is robust. Experimental results demonstrate its advantages. © 2006 IEEE.

Zhu H.T.,Tianjin University
Nonlinear Dynamics | Year: 2015

This paper studies the stationary probability density function (PDF) of a vibro-impact Duffing system under external Poisson impulses. A one-sided constraint is located at the equilibrium position of the system, and the system collides with the constraint by instantaneous repetitive impacts. A recently proposed solution procedure is extended to the case of Poisson impulses including three steps. First, the Zhuravlev non-smooth coordinate transformation is utilized to make the original Duffing system and impact condition be integrated into one equation. An additional impulsive damping term is introduced in the new equation. Second, the PDF of the new system is obtained with the exponential–polynomial closure method by solving the generalized Fokker–Planck–Kolmogorov equation. Last, the PDF of the original system is established following the methodology on seeking the PDF of a function of random variables. In numerical analysis, different levels of nonlinearity degree and excitation intensity are considered in four illustrative examples to show the effectiveness of the proposed solution procedure. The numerical results show that when the polynomial order is taken as six in the proposed solution procedure, it can present a satisfactory PDF solution compared with the simulated result. The tail region of the PDF solution is also approximated well for both displacement and velocity. © 2015 Springer Science+Business Media Dordrecht

Li X.,Tianjin University
International Journal of Energy Research | Year: 2016

Based on organic Rankine cycle (ORC), a trapezoidal cycle with theoretical model is proposed and built according to the trapezoidal configuration and the thermodynamic relation in T-s diagram. Simulations show that the relative deviation between trapezoidal cycle and ORC is lower than 5% within evaporation temperature of 5°C lower than the critical temperature of the working fluids. Empirical equations to calculate the optimal evaporation temperature, the maximum net power output and the corresponding thermal efficiency are built, which relative deviations from ORC are lower than 4%. Trapezoidal cycle can break through the restrictions of the actual working fluids and the configuration of the ORC to extend the study of the ORC and investigate the general principle of the ORC (or the trapezoidal cycle). Trapezoidal cycle can develop to trilateral cycle or Carnot cycle, which are the boundary cycles of the trapezoidal cycle. Trapezoidal cycle can be used as a general cycle to investigate the relations and principles among the trilateral cycle, Carnot cycle and trapezoidal cycle (or ORC). The performance of these three cycles at maximum power and their relations are investigated in the same conditions of finite heat source. Results show that the maximum power and the corresponding thermal efficiency of the trapezoidal cycle are bounded between Carnot cycle and trilateral cycle. © 2016 John Wiley & Sons, Ltd.

Li J.,University of Western Australia | Hao H.,Tianjin University | Hao H.,University of Western Australia
International Journal of Impact Engineering | Year: 2014

Spall damage is a typical damage mode of concrete structures under blast or high velocity impact loads. Blast and impact loads generate a stress wave propagating in the structure. At the opposite side from which the structural element is impulsively loaded, spall will occur if the net primary stresses over an area exceed the concrete dynamic tensile strength and the resistance force such as the material dynamic bond and interlock. Fragments of structural element generated from spall damage could eject with large velocities, and impose significant threats to equipment and personnel even it does not necessarily greatly reduce the load carrying capacity of the structural components. In the present study, spall damage of generic reinforced concrete columns subjected to blast loads is investigated numerically. Three-dimensional numerical models are developed to predict the concrete spalling under blast loads. The accuracy of the numerical simulations is verified with blast testing data reported by other researchers. Intensive numerical simulations are then carried out to investigate the influences of the column dimensions and reinforcement mesh on concrete spall damage. Based on numerical simulation data, empirical relations are suggested to predict concrete spall damage based on explosion scenarios, column dimensions and reinforcement conditions. © 2014 Elsevier Ltd. All rights reserved.

Nor N.M.,Ritsumeikan University | Ma S.,Ritsumeikan University | Ma S.,Tianjin University
Bioinspiration and Biomimetics | Year: 2014

This paper presents a locomotion control based on central pattern generator (CPG) of a snake-like robot. The main point addressed in this paper is a method that produces a smooth transition of the body shape of a snake-like robot. Body shape transition is important for snake-like robot locomotion to adapt to different space widths and also for obstacle avoidance. By manipulating the phase difference of the CPG outputs instantly, it will results in a sharp point or discontinuity which lead to an unstable movement of the snake-like robot. To tackle the problem, we propose a way of controlling the body shape: by incorporating activation function in the phase oscillator CPG model. The simplicity of the method promises an easy implementation and simple control. Simulation results and torque analysis confirm the effectiveness of the proposed control method and thus, can be used as a locomotion control in various potential applications of a snake-like robot. © 2014 IOP Publishing Ltd.

Rai A.C.,Purdue University | Chen Q.,Purdue University | Chen Q.,Tianjin University
Atmospheric Environment | Year: 2012

Ozone is a major pollutant of indoor air. Many studies have demonstrated the adverse health effect of ozone and the byproducts generated as a result of ozone-initiated reactive chemistry in an indoor environment. This study developed a Computational Fluid Dynamics (CFD) model to predict the ozone distribution in an aircraft cabin. The model was used to simulate the distribution of ozone in an aircraft cabin mockup for the following cases: (1) empty cabin; (2) cabin with seats; (3) cabin with soiled T-shirts; (4) occupied cabin with simple human geometry; and (5) occupied cabin with detailed human geometry. The agreement was generally good between the CFD results and the available experimental data. The ozone removal rate, deposition velocity, retention ratio, and breathing zone levels were well predicted in those cases. The CFD model predicted breathing zone ozone concentration to be 77-99% of the average cabin ozone concentration depending on the seat location. The ozone concentration at the breathing zone in the cabin environment can better assess the health risk to passengers and can be used to develop strategies for a healthier cabin environment. © 2012 Elsevier Ltd.

Wei G.,Kings College London | Dai J.S.,Kings College London | Dai J.S.,Tianjin University
Journal of Mechanical Design, Transactions of the ASME | Year: 2014

This paper presents two integrated planar-spherical overconstrained mechanisms that are inspired and evolved from origami cartons with a crash-lock base. Investigating the crash-lock base of the origami cartons, the first overconstrained mechanism is evolved by integrating a planar four-bar linkage with two spherical linkages in the diagonal corners. The mechanism has mobility one and the overconstraint was exerted by the two spherical linkages. This mechanism is then evolved into another integrated planar-spherical overconstrained mechanism with two double-spherical linkages at the diagonal corners. The evolved mechanism has mobility one. It is interesting to find that the double-spherical linkage at the corner of this new mechanism is an overconstrained 6R linkage. The geometry evolution is presented and the constraint matrices of the mechanisms are formulated using screw-loop equations verifying mobility of the mechanisms. The paper further reveals the assembly conditions and geometric constraint of the two overconstrained mechanisms. Further, with mechanism decomposition, geometry and kinematics of the mechanisms are investigated with closed-form equations, leading to comparison of these two mechanisms with numerical simulation. The paper further proposes that the evolved overconstrained mechanism can in reverse lead to new origami folds and crease patterns. The paper hence not only lays the groundwork for kinematic investigation of origami-inspired mechanisms but also sheds light on the investigation of integrated overconstrained mechanisms. Copyright © 2014 by ASME.

Wang Z.,Tianjin University | Liang M.,Tianjin University of Technology | Wang L.,Tianjin University of Technology | Hao Y.,Tianjin University of Technology | And 3 more authors.
Chemical Communications | Year: 2013

Three dithieno[3,2-b:2′,3′-d]pyrrole (DTP) units with different hexyloxyphenyl (HOP) substituents have been developed for triphenylamine organic dyes (XS54-XS56). The introduction of the 4-HOP-DTP unit has resulted in a stronger light harvesting capacity, accounting for the observed photocurrent enhancement in the case of XS54, while the 2-HOP-DTP/2,4-HOP-DTP units induce a strikingly large photovoltage improvement in the cases of XS55 and XS56 due to their higher steric hindrance. © 2013 The Royal Society of Chemistry.

Zhu H.T.,Tianjin University
Journal of Sound and Vibration | Year: 2014

This study presents a solution procedure for the stationary probability density function (PDF) of the response of vibro-impact Duffing oscillators under external and parametric Gaussian white noises. First the Zhuravlev non-smooth coordinate transformation is adopted to convert a vibro-impact oscillator into an oscillator without barriers. The stationary PDF of the converted oscillator is governed by the Fokker-Planck (FP) equation. The FP equation is solved by the exponential-polynomial closure (EPC) method. Illustrative examples are presented with vibro-impact Duffing oscillators under external and parametric Gaussian white noises to show the effectiveness of the solution procedure. The parametric excitation is acting in displacement and the constraint is a unilateral zero-offset barrier. The restitution coefficient of impacts is taken as 0.90. Comparison with the simulated results shows that the proposed solution procedure can provide good approximate PDFs for displacement and velocity although a little difference exists in the tail of these PDFs. This difference may be due to the weak approximation on the response of the vibro-impact oscillators using a continuous Markov process when the restitution coefficient is not very close to unity. © 2013 Elsevier Ltd.

Liu C.-J.,Tianjin University | Burghaus U.,North Dakota State University | Besenbacher F.,University of Aarhus | Wang Z.L.,Georgia Institute of Technology
ACS Nano | Year: 2010

The use of nanotechnology to develop a suite of sustainable energy production schemes is one of the most important scientific challenges of the 21st century. The challenge is to design, to synthesize, and to characterize new functional nanomaterials with controllable sizes, shapes, and/or structures. To summarize the progress of the research and development made in this important field, the Fuel Chemistry Division of the American Chemical Society (ACS) organized a symposium on "Nanotechnology for Sustainable Energy and Fuels" during the 240th ACS National Meeting in Boston, MA on August 22-26, 2010, with the ACS Catalysis Division as the cosponsor. This symposium was a global gathering of leading scientists at the intersection of energy and nanotechnology. The topics discussed at the symposium included nanotechnology, not only for traditional fossil fuel production but also for novel processes for renewable energy applications. This article aims to highlight some of the most exciting advances presented at the symposium, including the preparation and characterization of nanomaterials for clean fuel production, CO2 capture, solar cells and solar fuels, energy conversion and storage materials, hydrogen storage materials, and fuel cells. Finally, possible future developments in this important and timely area are discussed. © 2010 American Chemical Society.

Chen Z.L.,Tianjin University
Zhongguo zhen jiu = Chinese acupuncture & moxibustion | Year: 2011

According to the theory and method of standardization, based on the current situation and characteristics of acupuncture standardized research, eight important aspects are introduced in our project of acupuncture standardization. The acupuncture standard is summarized from different expert's experiences, thus it will not impede the effectiveness of a treatment by an individual doctor; the classical literature is the principle of acupuncture standard, and the scientific investigation is the basis of acupuncture standard; the acupuncture standard should emphasize the combination of application and science; the standard itself and different standards should be in consistent; the state acupuncture standard should be in agreement with the international standards; the acupuncture standardization is to establish the optimum order in order to achieve the optimum effectiveness of the treatment; the law and organizations are the instructions, and the current acupuncture standard is the recommended standard; acupuncture standardization should reflect the characteristics of traditional Chinese medicine.

Jia M.,Dalian University of Technology | Xie M.,Dalian University of Technology | Wang T.,Tianjin University | Peng Z.,University of Sussex
Applied Energy | Year: 2011

A full-cycle computational fluid dynamics (CFD) simulation coupled with detailed chemical kinetics mechanism has been used to investigate the effect of start of injection (SOI) timing and intake valve close (IVC) timing on performance and emissions of diesel premixed charge compression ignition (PCCI) engine. By sweeping SOI timing from -35 to -5. °CA ATDC and IVC timing from -140 to -80. °CA ATDC with fixed 50% exhaust gas recirculation (EGR) and 1.8. bar intake pressure, the contour plots for ignition timing, nitric oxides (NO. x), soot, hydrocarbon (HC), carbon monoxide (CO), indicated specific fuel consumption (ISFC), and ringing intensity have been developed. The results indicate that the operating range can be divided into kinetically controlled region and mixing-controlled region, in which the ignition timing is solely controlled by IVC timing and SOI timing respectively. To Minimize HC, CO, NO. x and soot emissions, SOI timing must be carefully adjusted within a limited range. With the retarded IVC timing, the operating range of SOI becomes wider for clean combustion. The IVC timing should be optimized with consideration of ignition timing and combustion efficiency at different SOI timing in order to improve fuel economy. For purpose of avoiding engine knock, the SOI timing around -20. °CA ATDC and early IVC timing are pursued. © 2011 Elsevier Ltd.

Zhou W.,Hong Kong Polytechnic University | Lou C.,Tianjin University | Li Z.,Hong Kong Polytechnic University | Lu L.,Hong Kong Polytechnic University | Yang H.,Hong Kong Polytechnic University
Applied Energy | Year: 2010

Solar and wind energy systems are omnipresent, freely available, environmental friendly, and they are considered as promising power generating sources due to their availability and topological advantages for local power generations. Hybrid solar-wind energy systems, uses two renewable energy sources, allow improving the system efficiency and power reliability and reduce the energy storage requirements for stand-alone applications. The hybrid solar-wind systems are becoming popular in remote area power generation applications due to advancements in renewable energy technologies and substantial rise in prices of petroleum products. This paper is to review the current state of the simulation, optimization and control technologies for the stand-alone hybrid solar-wind energy systems with battery storage. It is found that continued research and development effort in this area is still needed for improving the systems' performance, establishing techniques for accurately predicting their output and reliably integrating them with other renewable or conventional power generation sources. © 2009 Elsevier Ltd.

Wang W.,Tsinghua University | Wang W.,Tianjin University
Fuel Processing Technology | Year: 2010

Thermodynamics of glycerol partial oxidation for hydrogen production has been studied by Gibbs free energy minimization method. The optimum conditions for hydrogen production are identified: reaction temperatures between 1000 and 1100 K and oxygen-to-glycerol molar ratios of 0.4-0.6 at 1 atm. Under the optimal conditions, complete conversion of glycerol, 78.93%-87.31% yield of hydrogen and 75.12%-87.97% yield of carbon monoxide could be achieved in the absence of carbon formation. The glycerol partial oxidation with O2 is suitable for providing hydrogen-rich fuels for Molten Carbonate Fuel Cell and Solid Oxide Fuel Cell. The carbon-formed and carbon-free regions are found, which are useful in guiding the search for suitable catalysts for the reaction. Inert gases have a positive effect on the hydrogen and carbon monoxide yields. © 2010 Elsevier B.V.

Wang W.,Tsinghua University | Cao Y.,Tianjin University
International Journal of Hydrogen Energy | Year: 2010

Butanol partial oxidation for hydrogen-rich gas production has been studied by Gibbs free energy minimization method. The optimum conditions for hydrogen-rich gas production are identified: reaction temperatures between 1115 and 1200 K and oxygen-to-butanol molar ratios between 1.6 and 1.7 at 1 atm. Under the optimal conditions, complete conversion of butanol, 93.07%-96.56% yield of hydrogen and 94.02%-97.55% yield of carbon monoxide could be achieved in the absence of coke formation. The butanol partial oxidation with O 2 is suitable for providing hydrogen-rich fuels for Solid Oxide Fuel Cell (SOFC). Higher pressures have a negative effect, but inert gases have a positive effect, on the hydrogen yield. Coke tends to form at lower temperatures and lower oxygen-to-butanol molar ratios. © 2010 Professor T. Nejat Veziroglu. Published by Elsevier Ltd. All rights reserved.

Shi Y.,Tianjin University | Kurata M.,Kyoto University | Nakashima M.,Kyoto University
Earthquake Engineering and Structural Dynamics | Year: 2014

A series of full-scale shaking table tests were conducted at E-Defense for a four-story base-isolated hospital. The operation room in the specimen was chosen for detailed examination of its disorder and damage during large ground motions. It was arranged with various medical appliances in as a realistic manner as possible, and the appliances were characterized by casters installed at the bottom to ensure mobility. Two types of ground motion, the near-fault ground motion and long-period ground motion, were adopted, and the responses of the appliances were recorded using the motion capture technique. Thanks to the base isolation, the floor response was greatly reduced, and no disorder or damage was observed in the operation room except for the case when subjected to a long-period ground motion. In this case, the unlocked appliances moved seriously (by more than 3m), and collisions occurred between the appliances and between appliances and the surrounding wall. The force of collision reached 36kN, which is sufficient to injure a person. The acceleration due to collision was as high as 10g, which is far beyond what can be tolerated by acceleration-sensitive appliances. It is notable that such large motion was not observed once the appliances were locked. The test was also carried out for the corresponding fixed-base structure. Among all cases in the experiment, by far the most serious damage occurred in the fixed-base structure when subjected to the near-fault ground motion, clearly because the floor response was significantly amplified from the ground motion. © 2014 John Wiley and Sons, Ltd.

Huang G.,Tianjin University
Organic Letters | Year: 2015

The rhodium-catalyzed cyclopropanation/cyclization of allenynes was investigated by means of DFT calculations. The results show that the cyclopropanation via the proposed stepwise C(sp3)-H activation (σ-bond metathesis/C-H reductive elimination) was kinetically unfavorable. Instead, a concerted C(sp3)-H activation pathway, namely the metal-assisted σ-bond metathesis, in which the hydrogen was directly transferred to the rhodacyclopentane assisted by the Rh center followed by a C-C reductive elimination, was found to explain the experimental results. © 2015 American Chemical Society.

Fu H.,Tianjin University | Cao X.,Chinese Academy of Sciences | Tu Z.,University of California at Los Angeles
IEEE Transactions on Image Processing | Year: 2013

Co-saliency is used to discover the common saliency on the multiple images, which is a relatively underexplored area. In this paper, we introduce a new cluster-based algorithm for co-saliency detection. Global correspondence between the multiple images is implicitly learned during the clustering process. Three visual attention cues: contrast, spatial, and corresponding, are devised to effectively measure the cluster saliency. The final co-saliency maps are generated by fusing the single image saliency and multiimage saliency. The advantage of our method is mostly bottom-up without heavy learning, and has the property of being simple, general, efficient, and effective. Quantitative and qualitative experiments result in a variety of benchmark datasets demonstrating the advantages of the proposed method over the competing co-saliency methods. Our method on single image also outperforms most the state-of-the-art saliency detection methods. Furthermore, we apply the co-saliency method on four vision applications: co-segmentation, robust image distance, weakly supervised learning, and video foreground detection, which demonstrate the potential usages of the co-saliency map. © 1992-2012 IEEE.

Zhang P.,Nankai University | Li K.,Nankai University | Liu X.,Tianjin University
Journal of Power Sources | Year: 2014

Highly active and low-cost electrocatalysts are of great importance for large-scale commercial applications of microbial fuel cells (MFCs). In this work, we prepared an activated carbon (AC) air cathode containing electrodeposited γ-MnO2 using a potentiostatic method. The results indicated that carnation-like MnO2 crystals were bound to the surface of the AC air cathode after a deposition time of 10 min, which greatly improved the performance of the cathode. BET analysis results demonstrated that the electrodeposition of MnO2 decreased the micropore surface area of the cathode but increased the mesopore surface area. When compared with a bare AC air cathode, the electrodeposited MnO2 cathode exhibited higher catalytic activity for oxygen reduction reaction. The maximum power density of the MFC equipped with the electrodeposited MnO2 AC air cathode was 1554 mW m-2, which is 1.5 times higher than the control cathode. © 2014 Elsevier B.V. All rights reserved.

Armstrong S.,Australian National University | Wang M.,Peking University | Teh R.Y.,Swinburne University of Technology | Gong Q.,Peking University | And 7 more authors.
Nature Physics | Year: 2015

Einstein, Podolsky and Rosen (EPR) pointed out in their famous paradox that two quantum-entangled particles can have perfectly correlated positions and momenta. Such correlations give evidence for the nonlocality of quantum mechanics and form the basis for quantum cryptography and teleportation. EPR steering is the nonlocality associated with the EPR paradox and has traditionally been investigated between only two parties. Using optical networks and efficient detection, we present experimental observations of multiparty EPR steering and of the genuine entanglement of three intense optical beams. We entangle the quadrature phase amplitudes of distinct fields, in analogy to the position-momentum entanglement of the original paradox. Our experiments complement tests of quantum mechanics that have entangled small systems or have demonstrated tripartite inseparability. Our methods establish principles for the development of multiparty quantum communication protocols with asymmetric observers, and can be extended to qubits, whether photonic, atomic, superconducting, or otherwise. © 2015 Macmillan Publishers Limited.

Ke H.-W.,Tianjin University | Li X.-Q.,Nankai University
European Physical Journal C | Year: 2011

While the light-front quark model (LFQM) is employed to calculate hadronic transition matrix elements, the vertex functions must be pre-determined. In this work we derive the vertex functions for all d-wave states in this model. Especially, since both 3D1 and 3S1 are 1-- mesons, the Lorentz structures of their vertex functions are the same. Thus when one needs to study the processes where 3D1 is involved, all the corresponding formulas for 3S1 states can be directly applied; only the coefficient of the vertex function should be replaced by that for 3D1. The results would be useful for studying the newly observed resonances, which are supposed to be d-wave mesons, and furthermore possible 2S-1D mixing in ψ′ with the LFQM. © 2011 Springer-Verlag / Società Italiana di Fisica.

Jiao Y.,University of Adelaide | Zheng Y.,University of Adelaide | Jaroniec M.,Kent State University | Qiao S.Z.,University of Adelaide | Qiao S.Z.,Tianjin University
Chemical Society Reviews | Year: 2015

A fundamental change has been achieved in understanding surface electrochemistry due to the profound knowledge of the nature of electrocatalytic processes accumulated over the past several decades and to the recent technological advances in spectroscopy and high resolution imaging. Nowadays one can preferably design electrocatalysts based on the deep theoretical knowledge of electronic structures, via computer-guided engineering of the surface and (electro)chemical properties of materials, followed by the synthesis of practical materials with high performance for specific reactions. This review provides insights into both theoretical and experimental electrochemistry toward a better understanding of a series of key clean energy conversion reactions including oxygen reduction reaction (ORR), oxygen evolution reaction (OER), and hydrogen evolution reaction (HER). The emphasis of this review is on the origin of the electrocatalytic activity of nanostructured catalysts toward the aforementioned reactions by correlating the apparent electrode performance with their intrinsic electrochemical properties. Also, a rational design of electrocatalysts is proposed starting from the most fundamental aspects of the electronic structure engineering to a more practical level of nanotechnological fabrication. © 2015 The Royal Society of Chemistry.

Shi G.,Tianjin University | Voyiadjis G.Z.,Louisiana State University
Journal of Applied Mechanics, Transactions ASME | Year: 2011

This paper presents the derivation of a new beam theory with the sixth-order differential equilibrium equations for the analysis of shear deformable beams. A sixth-order beam theory is desirable since the displacement constraints of some typical shear flexible beams clearly indicate that the boundary conditions corresponding to these constraints can be properly satisfied only by the boundary conditions associated with the sixth-order differential equilibrium equations as opposed to the fourth-order equilibrium equations in Timoshenko beam theory. The present beam theory is composed of three parts: the simple third-order kinematics of displacements reduced from the higher-order displacement field derived previously by the authors, a system of sixth-order differential equilibrium equations in terms of two generalized displacements w and φx of beam cross sections, and three boundary conditions at each end of shear deformable beams. A technique for the analytical solution of the new beam theory is also presented. To demonstrate the advantages and accuracy of the new sixth-order beam theory for the analysis of shear flexible beams, the proposed beam theory is applied to solve analytically three classical beam bending problems to which the fourth-order beam theory of Timoshenko has created some questions on the boundary conditions. The present solutions of these examples agree well with the elasticity solutions, and in particular they also show that the present sixth-order beam theory is capable of characterizing some boundary layer behavior near the beam ends or loading points. Copyright © 2011 by ASME.

Leng Y.-G.,Tianjin University
Wuli Xuebao/Acta Physica Sinica | Year: 2011

For clarifying the response of a bistable system to a high-frequency signal, the mechanism of high-frequency resonance with parameter-adjusted bistable system is investigated. It was shown that the method of twice sampling frequency transformation does not change the bistable system structure to realize resonance at the low frequency corresponding to the high frequency, and that the method of tuning bistable system parameters can directly realize resonance at the high frequency through adjusting the system parameters to change the system structure. The reason for the realization of high-frequency stochastic resonance of tuning system parameters is that adjusting the two parameters of the bistable system simultaneously leads to no limiting value for Kramers rate, and hence the limitation of stochastic resonance frequency within small frequency range is broken through. © 2011 Chinese Physical Society.

Continuous SAPO-34 molecular sieve membranes have been rapidly synthesized on porous α-Al2O3 supports by secondary growth in the absence of organic templates under microwave-assisted heating. The thus obtained SAPO-34 membranes exhibit CO2-CH4 separation selectivity as high as 256, with CO2 permeance higher than 1.68 × 10-6 mol m-2 s-1 Pa-1 at 295 K for a pressure drop of 0.14 MPa. © The Royal Society of Chemistry 2015.

Kou X.,Cornell University | Kou X.,Tianjin University | Watkins C.B.,Cornell University | Gan S.-S.,Cornell University
Journal of Experimental Botany | Year: 2012

Arabidopsis has been used as a model system to study many aspects of plant growth and development. However, fruit senescence in Arabidopsis has been less investigated and the underlying molecular and hormonal (especially ethylene) regulatory mechanisms are not well understood. It is reported here that the Arabidopsis silique has characteristics of a climacteric fruit, and that AtNAP, a NAC family transcription factor gene whose expression is increased with the progression of silique senescence, plays an important role in its senescence. Silique senescence was delayed for 4-5 d in the atnap knockout mutant plants. The ethylene climacteric was delayed for 2 d in the atnap silique and the associated respiratory climacteric was suppressed. Exogenous ethylene stimulated respiration in the wild type, but not in the atnap mutant. The decoupling of the ethylene and respiratory climacterics in the atnap mutant suggests that AtNAP is required for ethylene stimulation of respiration. qPCR analyses revealed that the expression patterns of genes involved in ethylene biosynthesis, perception, and signalling, ACS2, ETR1, CTR1, EIN2, EIN3, and ERF1, were also altered in the atnap mutant. The effects of exogenous ABA, SA, 6-BA, and NAA on ethylene production and respiration in siliques of the wild type and atnap mutant were also investigated. A model involving ABA-AtNAP-controlled stomatal opening in regulating ethylene-stimulated respiration in fruit senescence is presented. © 2012 The Author.

Yue C.-Y.,Nankai University | Ding G.-S.,Tianjin University | Liu F.-J.,Nankai University | Tang A.-N.,Nankai University
Journal of Chromatography A | Year: 2013

A novel approach based on surface molecularly imprinted technique is demonstrated for the synthesis of surface molecularly imprinted silica nanoparticles (MI-SiNPs) in aqueous media, using l-tryptophan (l-Trp) as template molecule. The MI-SiNPs were fully characterized by transmission electron microscopy (TEM), thermo gravimetric analysis (TGA) and atomic force microscopy (AFM), and the results showed MI-SiNPs thus prepared were uniform in particle size (~87nm) with a distinct core-shell structure with shell thickness of ~7nm. The terminal carboxyl groups endowed the MI-SiNPs with good water-compatibility, and so good suspension stability for MI-SiNPs in water-rich buffer solutions can be easily achieved without the addition of any other reagents. When MI-SiNPs were used as pseudostationary phases (PSPs) in electrokinetic chromatography (EKC) for the enantioseparation of Trp, a resolution of 2.73 can be achieved in less than 10min with symmetric peaks. These excellent separation features are mainly attributed to the fast mass transfer and good accessibility of the interaction sites locating at the surface of the MI-SiNPs. The effects of some important separation factors, e.g., pH and concentration of buffer solution, content of MI-SiNPs added, content of organic modifier in buffer solution, on the enantioseparation of Trp were studied, and an optimum separation condition of 30% (v/v) acetonitrile in 20mmolL-1 phosphate buffer (pH 7.0), with 0.50mgmL-1 MI-SiNPs added was ultimately selected. © 2013 Elsevier B.V.

Gao P.,Nankai University | Mao D.,Tianjin University | Mao D.,Shenyang Pharmaceutical University | Luo Y.,Nankai University | And 3 more authors.
Water Research | Year: 2012

The occurrence of sulfonamide and tetracycline resistance and their pollution profile in the aquaculture environment of Tianjin, northern China, were investigated. The presence of antibiotic-resistant bacteria was identified and the corresponding antibiotic resistance genes (ARGs) were quantified at 6 aquaculture farms in Tianjin. Sulfonamide-resistance genes were prevalent and their concentrations were the highest detected (3.0×10 -5 to 3.3×10 -4 for sul1/16S rDNA, 2.0×10 -4 to 1.8×10 -3 for sul2/16S rDNA) among the various ARGs, most likely because the use of sulfonamides is more prevalent than tetracyclines in this area. Bacillus was the most dominant bacterial genus in both sulfamethoxazole resistant bacteria (63.27% of the total resistant bacteria) and tetracycline-resistant bacteria (57.14% of the total resistant bacteria). At least two of those genes (tetM, tetO, tetT, tetW, sul1 and sul2) were detected in the isolates of Bacillus cereus, Bacillus subtilis, Bacillus megaterium and Acinetobacter lwofii, and all of the above genes were detected in B. cereus, suggesting the occurrence of multi-resistance in the studied area. The genetic transfer of sul1 between intestinal bacteria (e.g., Enterococcus spp.) and indigenous bacteria (e.g., Bacillus spp.) was implied by phylogenetic analysis. Several strains of resistant opportunistic pathogens (e.g., Acinetobacter spp.) were found in indigenous bacteria, which increase the risk of ARGs to public health. Overall, this is the first study to comprehensively investigate the antibiotic resistance profile by analyzing the species of antibiotic-resistant bacteria and adopting qualitative and quantitative methods to investigate ARGs at a typical aquaculture area in northern China. © 2012 Elsevier Ltd.

Han X.,Tianjin University | Gan Y.X.,University of Toledo
International Journal of Advanced Manufacturing Technology | Year: 2013

The surface planarization in the chemical mechanical planarization is mainly realized by the mechanical effect which depends on the micro-tribology behavior of nanoparticles. The material removal rate is decreased and micro-scratch is generated in the wafer surface due to the agglomeration of particles. The slurry particles hold definite energy level and microstructure which makes the classical materials processing theory unable to give reasonable explanation about this process. Large-scale classical molecular dynamic simulation of interaction among nanoparticles and solid surface has been carried out to investigate the evolvement mechanism of particle cluster and surface planarization. It is showed that the particle aggregation behavior is a size-dependent process because of the high ratio of surface atoms to bulk atoms which leads to the active reactivity and catalytic activity of nanoparticles. The substrate materials (nanoparticle) become transforming from low-energy stable system to high-energy unstable system after the two-body collision which is favorable for aggregation process. There exists obvious geometry boundary between the particle elements in the large aggregates and only the dendritic aggregates formed. The larger particles have definite microstructure and additional internal degree of freedom which can be used to take up, store, and transfer energy, thus lower the activity of chemical reaction which weaken the particle aggregation process. © 2012 Springer-Verlag London Limited.

Pang Y.,Tianjin University | Li X.,CAS Xian Institute of Optics and Precision Mechanic | Yuan Y.,Aston University
IEEE Transactions on Circuits and Systems for Video Technology | Year: 2010

Tensor analysis plays an important role in modern image and vision computing problems. Most of the existing tensor analysis approaches are based on the Frobenius norm, which makes them sensitive to outliers. In this paper, we propose L1-norm-based tensor analysis (TPCA-L1), which is robust to outliers. Experimental results upon face and other datasets demonstrate the advantages of the proposed approach. © 2006 IEEE.

Liang J.,University of Adelaide | Du X.,University of Adelaide | Gibson C.,Flinders University | Du X.W.,Tianjin University | Qiao S.Z.,University of Adelaide
Advanced Materials | Year: 2013

A novel nitrogen doped hybrid material composed of in situ-formed graphene natively grown on hierarchical ordered porous carbon is prepared, which successfully combines the advantages of both materials, such as high surface area, high mass transfer, and high conductivity. The outstanding structural properties of the resultant material render it an excellent metal-free catalyst for electrochemical oxygen reduction. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Harik R.F.,Lebanese American University | Gong H.,Tianjin University | Bernard A.,CNRS Research Institute of Communication and Cybernetics of Nantes
CAD Computer Aided Design | Year: 2013

Flank milling is of importance to machining aircraft structural parts, turbines, blades and several other mechanical parts. It decreases manufacturing time, enhances quality and reduces cost. Since flank milling developable ruled surfaces do not contain geometrical errors, research on flank milling focuses on the generation of optimal tool trajectory for non-developable ruled surfaces, even generic free-form surfaces. This includes: envelope surfaces, geometrical errors (overcut, undercut), energy optimization in tool movement, surface deviations, tool geometry adaptation, tool wear and temperature, and surface roughness. In this article we present a survey on flank milling as well as suggesting guidelines for future considerations in solving flank milling tool trajectory optimization. © 2012 Elsevier Ltd. All rights reserved.

Chen B.,Tianjin University
Physical Review C - Nuclear Physics | Year: 2016

J/ψ suppression with rapidity is studied with both a (3+1)-dimensional transport equation and hydrodynamics in detail at sNN=2.76 TeV Pb+Pb collisions. In the central rapidity region of the hot medium, the J/ψ nuclear modification factor shows weak rapidity dependence due to the boost invariance of the medium. But in the forward rapidity region for the entire transverse momentum bin, J/ψ regeneration is strongly suppressed due to the decreasing charm pair cross section. This makes J/ψ RAA(y) decrease with rapidity. The ratio rAA of the mean transverse momentum squared in AA collisions to that in pp collisions increases strongly in the forward rapidity region and is more sensitive to the J/ψ production mechanisms. © 2016 American Physical Society.

Lim J.M.,Yonsei University | Kim P.,Yonsei University | Yoon M.-C.,Yonsei University | Sung J.,Yonsei University | And 5 more authors.
Chemical Science | Year: 2013

Whilst the excitonic properties of J-aggregates have been investigated in great detail, those of H-aggregates have not been systematically investigated yet. In this regard, we have explored the exciton dynamics and excited-species formation processes in columnar H-aggregates of planar PBI dyes that are stacked in a helical fashion by various spectroscopic techniques such as time correlated single-photon counting and femtosecond pump-probe measurements with anisotropy changes. The outcome of this study is that photogenerated excitons in helically stacked PBI dyes experience complicated relaxation processes that involve excited-state interactions such as exciton delocalization and excimer formation. To scrutinize the exciton dynamics in the helically stacked aggregates, we have also included distorted bay-substituted PBI dyes as reference molecules that exhibit either no or only relatively small-sized dimeric aggregate structures. The comparative study revealed that the excited-state interactions in the large-sized helically stacked aggregates extend beyond two PBI units, leading to a final excimer (here, excimer means not only an "excited dimer" but an "excited multimer") trap state within ∼50 ps. Although in competition with this relaxation path into the excimeric trap state, exciton diffusion has been revealed by exciton-exciton annihilation processes, occurring at high excitation power. Whilst the excimer formation process interrupts the direct observation of exciton diffusion in these columnar PBI aggregates, the exciton migration distance could be estimated by the incorporation of non-fluorescent PBI quencher molecules. From this analysis we can conclude that the exciton diffusion can reach a length of about 10 monomer units. Although this value appears to be shorter than those values observed for J-aggregates, this result shows that columnar PBI stacks might still be useful for optoelectronic applications if the relaxation process leading to excimer traps is prevented, e.g. by structural modifications of the molecules. © 2013 The Royal Society of Chemistry.

Zhai H.,Tsinghua University | Shi L.,Tsinghua University | An Q.,Tianjin University
Energy | Year: 2014

The ORC (organic Rankine cycle) system is one of the most effective approaches for recovering energy from low grade heat sources like geothermal water. This paper describes the screen of fluids for geothermal ORC system. This study analyzed the influence of the working fluid properties of HC (hydro carbon) and HFC (hydro fluorine carbon) working fluids on the system performance and relates the properties to the molecular structures. HC and HFC working fluids were adopted. A theoretical ORC model was used to optimize the evaporating temperature to maximize the work output for each working fluid. The optimal working fluids are given for heat sources at 383.15K, 403.15K and 423.15K. The results show that for a specific source temperature, the optimized evaporating temperatures for all the working fluids are almost the same. Based on the influence of working fluid property on system performance, two indicators are given for screening working fluids. Fluids like R32, R134a and propylene with GWP (global warming potential)value less than1500 provide better performance than others, by extracting more energy from the heat source. © 2013 Elsevier Ltd.

This study employs a multiple-case study method, identifies barriers to the adoption of low carbon production, and categorizes these barriers into four domains: structural, regulatory, cultural, and contextual. The two most frequently mentioned barriers were "lack of financial incentives to stimulate low carbon innovation" and "lack of a common definition of low carbon production". The two least frequently mentioned barriers were "silos exist between planning and production" and "operational staff are often physically separated from planning staff, which isolates them from planning decisions". Furthermore, contextual barriers were significantly related to structural and regulatory barriers, while regulatory barriers were significantly related to structural barriers. Larger firms tend to have a more structured organization and lower perceptions of the employment term barrier. However, larger structured organizations have been affected by a long history of a planning-oriented economy and hence tend to have inflexible hierarchical systems. In contrast, small firms have hierarchical systems with less effect on low carbon production than those of large enterprises. Another interesting trend is the direct size effect on cultural barriers, which is evident in a culture of risk aversion, as well as the lack of low carbon technology and the existence of silos between planning and production. © 2013 Elsevier Ltd.

Long Z.,Tianjin University | Yao Q.,Tsinghua University
Powder Technology | Year: 2012

Numerical technology has been widely used for the study of the electrostatic precipitators (ESP) and the bag filters. This paper presents a numerical model for a scale hybrid particulate collector (HPC), which combines the ESP technology and the filtration technology together. The collection process of the HPC is unsteady as the pressure drop across the bag filter increases with the deposition of the particles. The physical processes of the model include the corona discharge, the fluid flow, the particle charging and the filtration. The corona discharge field is solved by using a finite volume method. For the fluid field, the unsteady and incompressible Navier-Stokes equations with the RNG κ- ε turbulence equations are solved. The effect of the electric field on the fluid field named electro-hydrodynamic is also considered. For the particle charging, the filed-diffusing combined model of Lawless (1996) [37] is adopted. For the filtration, an unsteady cake formation model is proposed. The pressure drop across the cake is calculated according to the mass density of the cake. The coefficient between the pressure drop and the mass density of the cake comes from the experimental data. Applying the numerical model to the HPC, the influence of the hole diameter of the perforated-plate on the collection efficiency of the electrostatic zone is analyzed. Numerical results show that the collection efficiency of the electrostatic zone of the HPC has no certain relation with the hole diameter of the perforated plate. The effect of the hole diameter of the perforated-plate on the collection efficiency of the electrostatic zone becomes weaker with increasing the applied voltage. © 2011 Elsevier B.V.

Zhang J.X.,Tianjin University | Liu L.,Capital University of Economics and Business | De Pablos P.O.,University of Oviedo | She J.,Capital University of Economics and Business
International Journal of Engineering Education | Year: 2014

Teaching and learning programming are the fun and also pain part for instructors and students in academic institutions, from the famous "Hello World" simple codes to advanced feature application software, thereis along and tough way to go for most of the students. Within limited teaching hours, instructor's presentation and explanation of the computer language are not attractive enough to raise and improve students' interest for learning proactively as students have different learning styles [1]. From the observation and the query, most students are more comfortable with learning by visual presentation-diagrams, video, animation, verbal explanation and trying things from their own interesting story. This paper describes a teaching approach for Java programming by using Alice-an innovative 3D programming environment that make it easy to help students learn fundamental programming concept in the context of creating animated movies and simple video games [2]. Evidence of students performance in learning Object-Oriented programming as a result of this approach are shown in this paper by statistical data that gathered, summarized and observed from fall semester of 2012. © 2014 TEMPUS Publications.

Considering that the safety coefficient is low when a shallow-buried long-span highway tunnel passes under an existing railway station (or within a short distance), the section of the Dongfu tunnel that passes under the existing Xiamen-Shenzhen railway station is taken as a project example in this paper. Through a theoretical analysis and technical comparison, an overall scheme of construction techniques is determined that is the combination of the following: reinforcing the tunnel's surrounding rock and soil mass in the excavation direction using the pipe-roofing method, setting the pile cap as provisional pier on the digging pile, structural selection and security checks for the digging pile, jacking up the existing railway track by erection of a 24m D-shaped beam, reinforcing the steel rail with a longitudinal and transverse lintel, reserving core soil in an arc-shaped heading, monitoring settlement, and analyzing the reinforcement effect. The results show that the reinforcement effect is remarkable, and can rapidly and effectively restrict stratum settling in the under-passing section; the pipe on the arc plays a load-bearing role while the D-shaped beam reduces the external load on the pipe-roofing system; thus, the safety coefficient of the under-passing tunnel and the existing railway operation is highly improved, and the expected effect is achieved. ©, 2014, Editorial Office of "Modern Tunnelling Technology". All right reserved.

Hong X.,University of Bristol | Hong X.,Tianjin University | Van Dijk E.M.P.H.,University of Twente | Hall S.R.,University of Bristol | And 3 more authors.
Nano Letters | Year: 2011

Metal nanoparticles play a key role in sensing and imaging. Here we demonstrate the detection of metal particles down to 5 nm in size with a signal-to-noise ratio of ∼7 using interferometric cross-polarization microscopy at ultralow excitation powers (∼1 μW) compatible with single molecule detection. The method is background-free and induces no heating as it operates far from plasmonic resonance. The combination of unlimited observation time and protein-sized metal nanoparticles has great potential for biophysical applications. © 2011 American Chemical Society.

Liang Y.,China Coal Research Institute | Zeng W.,Tianjin University
Journal of Hazardous Materials | Year: 2010

Through amending the SENKIN code of CHEMKIN III chemical kinetics package, a computational model of gas explosion in a constant volume bomb was built, and the detailed reaction mechanism (GRI-Mech 3.0) was adopted. The mole fraction profiles of reactants, some selected free radicals and catastrophic gases in the process of gas explosion were analyzed by this model. Furthermore, through the sensitivity analysis of the reaction mechanism of gas explosion, the dominant reactions that affect gas explosion and the formation of catastrophic gases were found out. At the same time, the inhibition mechanisms of water on gas explosion and the formation of catastrophic gases were analyzed. The results show that the induced explosion time is prolonged, and the mole fractions of reactant species such as CH4, O2 and catastrophic gases such as CO, CO2 and NO are decreased as water is added to the mixed gas. With the water fraction in the mixed gas increasing, the sensitivities of the dominant reactions contributing to CH4, CO2 are decreased and the sensitivity coefficients of CH4, CO and NO mole fractions are also decreased. The inhibition of gas explosion with water addition can be ascribed to the significant decrease of H, O and OH in the process of gas explosion due to the water presence. © 2009 Elsevier B.V. All rights reserved.

Xi G.,Japan International Center for Materials Nanoarchitectonics | Xi G.,Chinese Academy of Inspection and Quarantine | Ouyang S.,Japan International Center for Materials Nanoarchitectonics | Li P.,Japan International Center for Materials Nanoarchitectonics | And 6 more authors.
Angewandte Chemie - International Edition | Year: 2012

Open vacancies: A facile one-pot synthesis of oxygen-vacancy-rich ultrathin W 18O 49 nanowires up to several micrometers long is described. In addition to unique optical properties, such as NIR absorption and blue-light emission, the nanowires show an unexpected ability to photochemically reduce carbon dioxide to methane (see picture) as a result of its defect structure caused by large quantities of oxygen vacancies. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Luo X.,University of Electronic Science and Technology of China | Ma J.-G.,Tianjin University | Li E.-P.,Zhejiang University
IEEE Microwave and Wireless Components Letters | Year: 2011

In this letter, a compact wideband bandpass filter with a wide stopband is proposed. The filter is composed of three parts: a half-wavelength (λ/2) microstrip resonator with a loaded broadside-coupled microstrip/CPW (BCMC) stub, two λ/4 I/O feeding-lines, and two microstrip short-stubs. The loaded BCMC stub can not only introduce the perturbation to affect the λ/2 microstrip resonator acting as a dual-mode resonator, but also provide two transmission zeros to improve the upper passband selectivity and suppress the first odd-mode spurious. Then, to avoid the first even-mode spurious, two microstrip short-stubs are employed to obtain another transmission zero. Meanwhile, two λ/4 I/O feeding-lines are employed to obtain strong passband enhancement around the dual-resonances. To verify the mechanism mentioned above, a bandpass filter is designed. The proposed filter has the merits of low insertion loss, good passband selectivity, wide stopband, flat group delay, and a compact size. © 2011 IEEE.

Zuilhof H.,Wageningen University | Zuilhof H.,Tianjin University | Zuilhof H.,King Abdulaziz University
Accounts of Chemical Research | Year: 2016

ConspectusA series of diseases, ranging from cholera via travelers' diarrhea to hamburger disease, are caused by bacterially produced toxic proteins. In particular, a toxic protein unit is brought into the host cell upon binding to specific membrane-bound oligosaccharides on the host cell membrane. For example, the protein that causes cholera, cholera toxin (CT), has five identical, symmetrically placed binding pockets (B proteins), on top of which the toxic A protein resides. A promising strategy to counteract the devastating biological effects of this AB5 protein involves the development of inhibitors that can act as mimics of membrane-bound GM1 molecules, i.e., that can bind CT strongly and selectively. To reach this goal, two features are essential: First of all, the inhibitor should display oligosaccharides that resemble as much as possible the naturally occurring cell-surface pentasaccharide onto which CT normally binds, the so-called GM1 sugar (the oligosaccharide part of which is then labeled GM1os). Second, the inhibitor should be able to bind CT via multivalent interactions so as to bind CT as strongly as possible to allow for a real competition with the cell-membrane-bound GM1 molecules.In this Account, we present elements of the path that leads to strong CT inhibition by outlining the roles of multivalency and the development and use of GM1 mimics. First, multivalency effects were investigated using "sugar-coated" platforms, ranging from dendritic structures with up to eight oligosaccharides to platforms that mimicked the fivefold symmetry of CT itself. The latter goal was reached either via synthetic scaffolds like corannulene or calix[5]arene or via the development of a neolectin CT mimic that itself carries five GM1os groups. Second, the effect of the nature of the oligosaccharide appended to this platform was investigated via the use of oligosaccharides of increasing complexity, from galactose and lactose to the tetrasaccharide GM2os and eventually to GM1os itself. The combination of these threads gives rise to a series of inhibitors that can strongly bind CT, with IC50 values below 100 pM, and in some cases can even bind one-on-one. © 2016 American Chemical Society.

Luo X.,University of Electronic Science and Technology of China | Ma J.-G.,Tianjin University | Yeo K.S.,Nanyang Technological University | Li E.-P.,Zhejiang University
IEEE Transactions on Microwave Theory and Techniques | Year: 2011

In this paper, compact ultra-wideband (UWB) bandpass filters with ultra-narrow dual- and quad-notched bands are proposed using the broadside-coupled microstrip/coplanar waveguide (CPW) structure. The multiple-modes UWB operation is obtained through the CPW detached-mode resonator (DMR) and broadside-coupled microstrip/CPW transition. To avoid the existing interferences such as the wireless local-area network signals (i.e., 5.2- and 5.8-GHz bands) in the UWB passband simultaneously, dual-notched bands can be finely employed and independently adjusted by the embedded quarter-wavelength (λ/4) CPW resonators and the λ/4 meander slot-line inserted in the DMR, respectively. To further cancel the interferences from the 3.5-GHz worldwide interoperability for microwave access and 6.8-GHz RF identification communication, the λ/4 meander defected microstrip structure is employed. Based on the structures mentioned above, a series of UWB bandpass filters with dual- and quad-notched bands are then designed and fabricated. With good passband/stopband performances, compact size, and low cost, the proposed filters are attractive for the practical applications. © 2006 IEEE.

Zhu H.T.,Tianjin University
International Journal of Non-Linear Mechanics | Year: 2014

This paper proposes a solution procedure for the probability density function (PDF) solution of a vibro-impact Duffing system with a randomly varying damping term. The study considers the one-sided barrier located at the equilibrium of the system. The classical model with instantaneous impacts is used to model the colliding between the system and the barrier. First, the Zhuravlev non-smooth coordinate transformation is employed to convert the original vibro-impact system into a new system without any barrier by introducing an additional damping term. Second, the PDF of the new system is governed by the Fokker-Planck equation which is solved by the exponential-polynomial closure method. Last, the PDF of the original system is formulated in terms of the methodology on seeking the PDF of a function of random variables. Six illustrative examples are examined to show the effectiveness of the proposed solution procedure. The effects of the parameters, namely the non-linearity in displacement, the parametric excitation intensity, the negative linear stiffness and the restitution factor, are further investigated on the PDF distribution of the vibro-impact systems. Comparison with the simulated result shows that the proposed solution procedure can provide a satisfactory PDF solution for the examined examples. The tail region of the PDF is also approximated well. © 2014 Elsevier Ltd.

Hu J.,Tianjin University | Gao D.Z.,Northumbria University
Bioinformatics | Year: 2012

Motivation: Hepatitis B virus and hepatitis C virus are the two leading causes resulting in hepatocellular carcinoma (HCC). It is observed that hepatitis C virus (HCV) is relatively difficult to induce HCC compared with hepatitis B virus (HBV). This motivates us to reveal the reasons behind this from the viewpoint of immune genes.Results: To distinguish the immune genes with low-level expression in HBV-induced HCC, but high-level expression in HCV-induced HCC, the concept of distinction immune gene is proposed. A filter is then designed to screen these genes. By using gene positive network with strong correlations between genes, the genes are further filtered to form the set of key distinction immune genes. The 23 key distinction immune genes are screened, which are divided into four clusters, T cells, B cells, immune signalling and major histocompatibility complex. It is evident that the screened genes are important immune genes, which are activated in HCV-induced HCC, but inactivated in HBV-induced HCC. In HCV-induced HCC, the structures of HCV adaptively update, so that they are difficult to be identified by antigens. Therefore, the clinic advice is either to increase the update speed of antigens or reduce the update speed of the viruses during the treatment of HCV-induced HCC. Moreover, it is also advised to add T cells or add the expression levels of T cells to strengthen the ability to kill cancer cells. In contrast, HBV updates slowly, but the immunity system in HBV-induced HCC has been damaged seriously. As a result, the clinic advice is to improve the immune ability of patients subjected to HBV-induced HCC, such as increasing immunoglobulin, T cells and B cells and so forth. © 2012 The Author.

Qin Y.,Nanjing Southeast University | Chen Z.,Tianjin University
Steel and Composite Structures | Year: 2016

Cold-formed steel structures are increasingly attractive due to their benefits of good mechanical performance and constructional advantages. However, this type of construction is still not fully exploited as a result of the acknowledged difficulties involved in forming construction-efficient and cost-effective connections. Furthermore, there is a lack of information on the structural behavior of the cold-formed steel connections. In this study, the research on various cold-formed steel connections was comprehensively reviewed from both fundamental and structural points of view, based on the available experimental and analytical data. It reveals that the current design codes and guidelines for cold-formed steel connections tend to focus more on the individual bearing capacity of the fasteners rather than the overall structural behavior of the connections. Significant future work remains to be conducted on the structural performance of cold-formed steel connection. In addition, extensive previous research has been carried out to propose and evaluate an economical and efficient connection system that is obtained from the conventional connecting techniques used in the hot-rolled industry. These connecting techniques may not be suitable, however, as they have been adopted from hot-rolled steel portal frames due to the thinness of the sheet in cold-formed steels. The review demonstrates that with the increasing demand for cold-formed steel constructions throughout the world, it is crucial to develop an efficient connection system that can be prefabricated and easily assembled on site. Copyright © 2016 Techno-Press, Ltd.

Precise DNA replication is critical for the maintenance of genetic integrity in all organisms. In all three domains of life, DNA replication starts at a specialized locus, termed as the replication origin, oriC or ORI, and its identification is vital to understanding the complex replication process. In bacteria and eukaryotes, replication initiates from single and multiple origins, respectively, while archaea can adopt either of the two modes. The Z-curve method has been successfully used to identify replication origins in genomes of various species, including multiple oriCs in some archaea. Based on the Z-curve method and comparative genomics analysis, we have developed a web-based system, Ori-Finder, for finding oriCs in bacterial genomes with high accuracy. Predicted oriC regions in bacterial genomes are organized into an online database, DoriC. Recently, archaeal oriC regions identified by both in vivo and in silico methods have also been included in the database. Here, we summarize the recent advances of in silico prediction of oriCs in bacterial and archaeal genomes using the Z-curve based method. © 2014 Bentham Science Publishers.

Lu J.,Jiangsu University of Science and Technology | Wang Y.-X.,Tianjin University | Zhu J.,Jiangsu University of Science and Technology
Electrochimica Acta | Year: 2010

The electrodeionization process (EDI) is usually operated at overlimiting current density, and is thus characterized by water dissociation and concentration polarization. We attempt to study the useful and harmful effects of water dissociation on the EDI process. A numerical steady state model was established to simulate the process of EDI, accounting for the effects of water dissociation. The differences in concentration polarization of membranes were investigated to study the effects of water dissociation on cation and anion membranes. Protons produced by water dissociation caused the resin to transform into the H-form. The H-form resin, which has high conductivity and high transport number, depletes protons in the interstitial solution. This explains the experimentally detected phenomenon that at high current densities, the pH value of the effluency of the dilute compartment (DC) stops decreasing when current increases. We suggest that the useful role of water dissociation in EDI is due to the H-form resin bringing more salt cations of the interstitial solution into the resin phase, thus producing a high conductivity channel for the electro-migration of the salt cations. This mechanism avoids the decrease in salt ion conductivity brought about by concentration polarization. The disadvantageous effect of concentration polarization on the transportation of salt ions in interstitial solution is thus lessened. An intermediate point between the useful and harmful effects of water dissociation was determined by the dependence of current efficiency and removal rate for both cations and anions as a function of current density. © 2009 Elsevier Ltd. All rights reserved.

Li X.,Pacific Northwest National Laboratory | Qi W.,Tianjin University | Mei D.,Pacific Northwest National Laboratory | Sushko M.L.,Pacific Northwest National Laboratory | And 2 more authors.
Advanced Materials | Year: 2012

By using a combination of theoretical and experimental techniques, it is demonstrated that functionalized graphene sheets (FGS) can function as a new class of molecular templates to direct the nucleation, crystalline phase transition, and self-assembly process of surfactant micelles and metal oxides. Novel, three-dimensional FGS-metal oxide nanocomposite materials with an ordered mesoporous structure can be synthesized. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Yang X.,Nanyang Technological University | Zhao D.,Nanyang Technological University | Leck K.S.,Nanyang Technological University | Tan S.T.,Nanyang Technological University | And 5 more authors.
Advanced Materials | Year: 2012

High-quality InP/ZnS core-shell nanocrystals with luminescence tunable over the entire visible spectrum have been achieved by a facile one-pot solvothermal method. These nanocrystals exhibit high quantum yields (above 60%), wide emission spectrum tunability and excellent photostability. The FWHM can be as narrow as 38 nm, which is close to that of CdSe nanocrystals. Also, making use of these nanocrystals, we further demonstrated a cadmium-free white QD-LED with a high color rendering index of 91. The high-performance of the resulting InP/ZnS NCs coupled with their low intrinsic toxicity may further promote industrial applications of these NC emitters. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

To verify the effect of bloodletting therapy at Jing-well points and semen coicis on patients with traumatic cerebral infarction. Ninety patients were randomized into a bloodletting therapy at Jing-well points group (bloodletting group), a semen coicis group and a comprehensive therapy group, 30 cases in each one. The conventional basic medication was applied in all of the three groups. In the bloodletting group, the bloodletting therapy was done at twelve Jing-well points with three-edged needle, 3 drops of blood required at each one, three times a day. In the semen coicis group, the semen coicis preparation was applied via nasal feeding or oral administration, 90 g each day, three times a day. In the comprehensive therapy group, the bloodletting therapy at twelve Jing-well points and semen coicis preparation were used in combination and the methods were same as the above two groups. After 4 weeks of treatment, the efficacy was assessed with nerve function defectscale (NDS). Fugl-Meyer scale of the upper and lower limb function was used to evaluate the motor function of the affected limbs of the patients before and after treatment. The scores of Fugl-Meyer scale of the upper and lower limb function were increased apparently after treatment in the patients of every group (P < 0.01, P < 0.05). The score increase was much more obvious in the bloodletting group and the comprehensive therapy group as compared with the semen coicis group (all P < 0.01). The result in the comprehensive therapy group was superior to the bloodletting group (all P < 0.05). The total effective rates of NDS in the comprehensive therapy group, bloodletting group and semen coicis group were 96.7% (29/30), 83.3% (25/30) and 76.7% (23/30) separately. The result in the comprehensive therapy group was higher apparently than those in the bloodletting group and semen coicis group separately (both P < 0.05). The result in the bloodletting group was better than that in the semen coicis group (P < 0.05). The bloodletting therapy at Jing-well points and semen coicis alleviate apparently nerve function defect, improve the motor function of the affected limbs and achieve the better efficacy.

Zhang R.,Wayne State University | Zhang C.-T.,Tianjin University
Current Genomics | Year: 2014

In theoretical physics, there exist two basic mathematical approaches, algebraic and geometrical methods, which, in most cases, are complementary. In the area of genome sequence analysis, however, algebraic approaches have been widely used, while geometrical approaches have been less explored for a long time. The Z-curve theory is a geometrical approach to genome analysis. The Z-curve is a three-dimensional curve that represents a given DNA sequence in the sense that each can be uniquely reconstructed given the other. The Z-curve, therefore, contains all the information that the corresponding DNA sequence carries. The analysis of a DNA sequence can then be performed through studying the corresponding Z-curve. The Z-curve method has found applications in a wide range of areas in the past two decades, including the identifications of protein-coding genes, replication origins, horizontally-transferred genomic islands, promoters, translational start sides and isochores, as well as studies on phylogenetics, genome visualization and comparative genomics. Here, we review the progress of Z-curve studies from aspects of both theory and applications in genome analysis. © 2014 Bentham Science Publishers.

Li R.Y.,Tianjin University | Zhang T.,University of Hong Kong | Fang H.H.P.,University of Hong Kong
Bioresource Technology | Year: 2011

This paper reviews the application of molecular techniques in heterotrophic hydrogen production studies. Commonly used molecular techniques are introduced briefly first, including cloning-sequencing after polymerase chain reaction (PCR), denaturing gradient gel electrophoresis (DGGE), terminal-restriction fragment length polymorphism (T-RFLP), fluorescence in situ hybridization (FISH) and quantitative real-time PCR. Application of the molecular techniques in heterotrophic hydrogen production studies are discussed in details, focusing on identification of new isolates for hydrogen production, characterization of microbial compositions in bioreactors, monitoring microbial diversity variation, visualization of microbial distribution in hydrogen-producing granular sludge, and quantification of various microbial populations. Some significant findings in recent hydrogen production studies with the application of molecular techniques are discussed, followed by a research outlook of the heterotrophic biohydrogen field. © 2011 Elsevier Ltd.

A kind of novel diamino moiety functionalized silica nanoparticles with the diameter of ∼110 nm was successfully prepared and characterised by transmission electron microscope (TEM) and elemental analysis. Capillary electrophoresis (CE) with this kind of nanoparticles as pseudostationary phase was developed for the simultaneous analysis of five organic acids in beverage and fruit samples. The effects of pH, buffer concentration, and nanoparticles concentration on separation were carefully investigated. Five organic acids were baseline separated in 5 min under optimum experimental conditions. The precisions for five replicate separations of a standard mixture solution were 2.71-6.13% for peak area and 1.22-1.93% for migration time respectively. The detection limits were 7.5, 0.15, 0.23, 0.33 and 10.0 mg/L for citric acid, salicylic acid, benzoic acid, sorbic acid and ascorbic acid, respectively. The developed method was applied to the simultaneous analysis of five analytes in beverage and fruit samples and certified reference materials with satisfactory results. © 2013 Published by Elsevier Ltd.

Huang S.,CAS Changchun Institute of Applied Chemistry | Jiang S.,Tianjin University
RSC Advances | Year: 2014

Biocompatible and biodegradable block copolymers (BBCPs) have become increasingly important in polymer science, and have many potential applications in polymer materials. The structures of BBCPs, which are determined by the competition between crystallization, microphase separation, kinetics and processing, have a tremendous influence on the final properties and applications. In this review, the most recent advances are highlighted in the crystalline structures and morphologies of BBCPs with at least one crystalline block. Particular emphasis is placed on the influences of chemical composition, molecular architecture, crystallization pathway, and film thickness on the structures and morphologies of the block copolymers. The formation and the characteristics of the structures grown in the block copolymers are helpful for understanding the interplay between crystallization and phase segregation, morphologies, structural evolution and their applications. © 2014 the Partner Organisations.

Wang W.,Tsinghua University | Cao Y.,Tianjin University
International Journal of Hydrogen Energy | Year: 2011

Thermodynamic equilibrium for sorption enhanced steam reforming of butanol (SESRB) to hydrogen was investigated using Gibbs free energy minimization method. The optimal operation conditions for SESRB are at 800 K, the steam-to-butanol molar ratio of 10, the calcium oxide-to-butanol molar ratio of 8 and atmospheric pressure. Under the optimal conditions, complete conversion of butanol, 97.07% concentration of H2 and 0.05% concentration of CO2, and efficiency of 86.60% could be achieved and at which no coke tends to form. Under the same conditions in SRB, 58.18% concentration of H 2, 21.62% concentration of CO2, and energy efficiency of 81.51% could be achieved. Butanol steam reforming with CO2 adsorption has the higher H2 content and efficiency, and lower CO2 content than that without adsorption under the same reaction conditions. In addition, reaction conditions for coke-free and coke-formed regions are also discussed in butanol steam reforming with or without CO2 separation. © 2010 Professor T. Nejat Veziroglu. Published by Elsevier Ltd. All rights reserved.

Zhang G.,Tianjin University | Liu W.,Curtin University Australia
IEEE Transactions on Automatic Control | Year: 2011

The problem of impulsive mode elimination for descriptor systems via a structured output proportional and derivative (P-D) feedback is investigated in this technical note. The motivation of solving this problem arises from an observation that the impulse behavior for some descriptor systems can not be eliminated completely by a parameterized output P-D feedback, but it can be removed by a structured P-D feedback elegantly designed. In order to explain this phenomenon explicitly, a concept of the structured P-D feedback is first introduced, then an explicit necessary and sufficient condition is constructively derived for the closed loop systems to be regular and impulse-free by the structured P-D feedback. The main result is represented in terms of the original system parameters instead of decomposed subsystem parameters. Finally, an example is provided to illustrate the effectiveness of the proposed result. © 2006 IEEE.

Zhang K.,Tianjin University | Zhang K.,University of Texas at Dallas
Journal of Visual Languages and Computing | Year: 2012

Recent great advances of information visualization and visual languages have not been utilized in the management field. This View point article advocates the use of appropriate visual languages in general and visualization in particular to maximize human's visual perceptual power for rapid and effective communication in management. © 2012 Elsevier Ltd.

Xia C.,Tianjin Polytechnic University | Xia C.,Tianjin University
Diangong Jishu Xuebao/Transactions of China Electrotechnical Society | Year: 2012

As a kind of efficient and clean renewable energy, wind energy receives much concern. Wind energy conversion system (WECS) based on permanent magnet synchronous generator (PMSG) has become one of the most significant development directions of wind energy technologies because of its outstanding comprehensive superiority. This paper discusses the structures, driven types and operation characteristics of PMSGs in WECSs. Then the topologies, controls and applications of the power converters suitable for WECSs based on PMSG are illustrated. The development trend of WECS based on PMSG technologies are analyzed finally. With rapid development of wind energy and its related technologies, the WESCs based on PMSGs will have broad prospects.

Han Y.,Tianjin University | Wu F.,Zhejiang University | Tian Q.,University of Texas at San Antonio | Zhuang Y.,Zhejiang University
IEEE Transactions on Image Processing | Year: 2012

Automatic image annotation (AIA) is very important to image retrieval and image understanding. Two key issues in AIA are explored in detail in this paper, i.e., structured visual feature selection and the implementation of hierarchical correlated structures among multiple tags to boost the performance of image annotation. This paper simultaneously introduces an input and output structural grouping sparsity into a regularized regression model for image annotation. For input high-dimensional heterogeneous features such as color, texture, and shape, different kinds (groups) of features have different intrinsic discriminative power for the recognition of certain concepts. The proposed structured feature selection by structural grouping sparsity can be used not only to select group-of-features but also to conduct within-group selection. Hierarchical correlations among output labels are well represented by a tree structure, and therefore, the proposed tree-structured grouping sparsity can be used to boost the performance of multitag image annotation. In order to efficiently solve the proposed regression model, we relax the solving process as a framework of the bilayer regression model for multilabel boosting by the selection of heterogeneous features with structural grouping sparsity (Bi-MtBGS). The first-layer regression is to select the discriminative features for each label. The aim of the second-layer regression is to refine the feature selection model learned from the first layer, which can be taken as a multilabel boosting process. Extensive experiments on public benchmark image data sets and real-world image data sets demonstrate that the proposed approach has better performance of multitag image annotation and leads to a quite interpretable model for image understanding. © 2012 IEEE.

Zhang X.,Tianjin University | De Pablos P.O.,University of Oviedo | Xu Q.,Huazhong University of Science and Technology
Computers in Human Behavior | Year: 2014

In multi-national and cross-cultural virtual classes, students' cultural values have significant impacts on knowledge sharing process. According to Hofstede's cultural dimensions, we conducted a mixed method to investigate how national cultural values effect on explicit and implicit knowledge sharing within a multi-national virtual class. First, we adopted a qualitative case study with 6 semi-structure interviews to explore the culture effects on knowledge sharing. Second, we conducted a cross-sectional survey to examine the interaction effects of culture and different knowledge sharing motivations. These findings suggest some cultural values (i.e.; collectivism) directly impact knowledge sharing, while most cultural values (i.e.; power distance, uncertainty avoidance, and Confucian dynamism) have interactive effects with knowledge sharing motivations. Furthermore, we also found some cultural values, like concern for face, have complex effects on knowledge sharing. This research contributes to the knowledge sharing literature, and provides practical implications for the organization work of computer-based education systems. © 2013 Elsevier Ltd. All rights reserved.

Li X.,Tianjin University | Sun J.-Q.,University of California at Merced
Physica A: Statistical Mechanics and its Applications | Year: 2016

Turning vehicles strongly influence traffic flows at intersections. Effective regulation of turning vehicles is important to achieve better traffic performance. This paper studies the impact of lane sharing and turning signals on traffic performance at intersections by using cellular automata. Both right-turn and left-turn lane sharing are studied. Interactions between vehicles and pedestrians are considered. The transportation efficiency, road safety and energy economy are the traffic performance metrics. Extensive simulations are carried out to study the traffic performance indices. It is observed that shared turning lanes and permissive left-turn signal improve the transportation efficiency and reduce the fuel consumption in most cases, but the safety is usually sacrificed. It is not always beneficial for the through vehicles when they are allowed to be in the turning lanes. © 2015 Elsevier B.V.

Li W.,Tianjin University | Sun J.,Tianjin University of Technology | Chen M.,Tianjin University of Technology
Nano Energy | Year: 2014

Harvest energy from our environment for driving small electronics is an effective and practically applicable technology. Here, we demonstrated a simple, cost-effective arch-shaped triboelectric nanogenerator (TENG), which is fabricated by utilizing the triboelectric effect and related electrostatic induction between a biodegradable metal foil and a polymer sheet, with bactericidal nano-Ag ink painted on its top as electrode. The power generation mechanism and the electric output of the TENG were studied and illustrated. The instantaneous output voltage and current density of such a flexible TENG can reach as high as ~160V and 6.6μA/cm2. Based on these characteristics of the TENG, it is anticipated that the TENG comprised of a biodegradable metal foil and a bactericidal Ag film has potential application in biomedical field to drive small biomedical devices possibly in-vivo. © 2013 Elsevier Ltd.

Chu J.,Nanyang Technological University | Yan S.W.,Tianjin University | Li W.,Tianjin Port CO.
Geotextiles and Geomembranes | Year: 2012

In recent years, global warming has caused the sea level to rise. The river or coastal related disasters such as tsunami, cyclone and flood have also become higher in frequency and stronger in intensity. As one of the counter measures, some of the existing coastal protection structures need to be rehabilitated and new, stronger or taller coastal structures have to be built. How to construct coastal protection structures in a quicker and yet cost-effective way has become a challenge to geotechnical engineers. In this paper, a few recent developments in dike construction and related methods and techniques are presented. A classification to the coastal protection structures is given according to materials used. Three innovative construction methods for coastal protection structures are introduced. These are geotextle mattress (or geomat), semi-circular precast concrete caisson, and suction caisson. The applications of these techniques in dike or breakwater construction are illustrated using case histories. A comparison of the three methods in terms of applicability, advantageous and disadvantageous is also made. © 2011 Elsevier Ltd.

Liu X.X.,Tianjin University | Chiew Y.-M.,Nanyang Technological University
Acta Geophysica | Year: 2012

This paper presents theoretical analyses and experimental results of seepage effects, especially downward seepage, on the initiation of cohesionless sediment particles. The theoretical analysis examines how the additional seepage force acts to modify the critical shear stress for sediment entrainment. Laboratory experiments were conducted using medium sand with diameter of 0.9 mm with downward seepage to quantitatively show suction effects on sediment entrainment. The critical shear stresses with different suction rates were calculated using the experimental results. The measured data together with published results provide an overall view on seepage effects on the initiation of cohesionless sediment transport. Depending on whether seepage is in the form of injection or suction, it will either increase or decrease the critical shear stress. The result reveals that the ratio of drag force at the threshold condition with seepage to that without seepage is dependent on the ratio of the hydraulic gradient with seepage to its value at the quick condition. © 2012 Versita Warsaw and Springer-Verlag Wien.

Yang Q.-H.,Tianjin University
Xinxing Tan Cailiao/New Carbon Materials | Year: 2011

The past twenty-five years have seen the discovery of three new carbon allotropes: fullerene, carbon nanotubes and graphene. Graphene, with an ideal two-dimensional structure, demonstrates many unique physical and chemical properties. This short review presents different "faces" of graphene in the eyes of physicists and chemists. For physicists, graphene means the thinnest platform to reveal new or unexpected properties of materials, while, for chemists, graphene acts as a basic and starting unit for desired structures with tuned properties. Thermal chemical exfoliation under mild and well-controllable conditions is highlighted as a feasible solution for the realization of mass-production and early applications of graphene-based materials.

Wenzhi G.,Tianjin University | Zhiyong H.,Zhejiang University
Mechanism and Machine Theory | Year: 2010

Reduction of shaft vibration is very important for safe and efficient functioning of a large turbo-generator. This paper presents a theoretical study and proposes an active vibration control scheme for controlling torsional vibration of a rotor shaft due to electromagnetic disturbances or unsteady flow in large steam turbine generator sets. A form of the conventional linear quadratic regulator (LQR) control algorithm has been proposed in this paper. The optimal LQR control problem is solved for each time interval with the weighting matrices, through the Ricatti equation, leading to time-varying gain matrices. The test is conducted using modified direct current electromotor as torsional vibration exciter and actuator, mounting on the rotor shaft. The actuator applies suitable force to control torsional vibration. Suitable force of actuation is achieved by varying the control current in the actuator depending upon a proportional and derivative control law. Preliminary theoretical study and test simulation show good reduction in torsional vibration response. © 2010 Elsevier Ltd. All rights reserved.

Ke H.-W.,Tianjin University | Li X.-Q.,Nankai University
Physical Review D - Particles, Fields, Gravitation and Cosmology | Year: 2011

Since the discovery of X(3872), its structure has been in ceaseless dispute. The data of X(3872)→π +π -π0J/ψ suggest that X(3872) may be a high-spin charmoniumlike particle of 2 -+. In terms of the light-front quark model we calculate the rates of the radiative decays X(3872)→J/ψ(ψ ′) γ supposing X(3872) to be a 2 -+ charmonium. Within this framework, our theoretical prediction on BR(X(3872)→ψ(1S)γ) is at order of 10 -3 which is slightly lower than the BABAR Collaboration's data but close to the Belle Collaboration's. Our prediction on BR(X(3872)→ψ ′γ) is at order of 10 -5 if ψ ′ is a pure 2S state or 10 -4 if ψ ′ is a 2S-1D mixture, which does not conflict with the upper bound set by Belle, but is much lower than BABAR's data. Thus if the future measurement decides the branching ratio of BR(X(3872) →ψ ′γ) to be much larger than 10 -4, the 2 -+ assignment for X(3872) should be ruled out. © 2011 American Physical Society.

Liu L.,Japan International Center for Materials Nanoarchitectonics | Ouyang S.,Japan International Center for Materials Nanoarchitectonics | Ye J.,Japan International Center for Materials Nanoarchitectonics | Ye J.,Tianjin University
Angewandte Chemie - International Edition | Year: 2013

Broadband visible-light harvesting over TiO2 is achieved by introducing gold nanorods (Au NRs) as antennas based on localized surface plasmon resonance. Furthermore, surfactant removal is achieved by an HClO 4 oxidative method. Not only transversal but also longitudinal plasma of Au NRs can induce photooxidation of 2-propanol, which extends the light harvesting to the near-infrared region. Scale bar: 10 nm. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Ren K.,Tianjin University | Ren X.,Tianjin University of Science and Technology
Applied Optics | Year: 2011

Light transport in a graded photonic crystal is studied using the finite-difference time-domain technique. The photonic crystal consists of a square lattice of elliptical dielectric rods. Within a frequency window, light can propagate inside the photonic crystal with the beam width nearly unchanged. The propagation direction can be easily manipulated by the structure gradient, which is achieved by gradually varying the orientation of the elliptical rods. The degree of control over the flow of light can be modulated by changing the ellipticity. This provides a promising approach to design of optical devices for spatial-beam routing. © 2011 Optical Society of America.

Wang S.,Tianjin University | Li Z.,Tianjin University | Wu L.,Clarkson University | Shahidehpour M.,Illinois Institute of Technology | Li Z.,Illinois Institute of Technology
IEEE Transactions on Power Systems | Year: 2013

This paper proposes a series of new metrics for the reliability and economic assessment of microgrids in distribution system. These metrics include reliability parameters for a microgrid in the islanded mode, indices indicating distributed generation (DG) and load characteristics in the microgrid, microgrid economic indices, and customer based microgrid reliability indices. A two-step Monte Carlo simulation (MCS) method is proposed to assess the reliability and economics of a microgrid with intermittent DGs as well as the reliability of distribution system with microgrids. An application in IEEE-RBTS shows the effectiveness of the reliability and economic assessment technique with the proposed metrics, which can provide scientific and comparative information for the design and operation of microgrids. © 1969-2012 IEEE.

Bai N.,University of Central Florida | Li G.,Tianjin University | Li G.,University of Central Florida
IEEE Photonics Technology Letters | Year: 2012

We propose single-carrier adaptive frequency-domain equalization (SC-FDE) for mode-division multiplexed transmission. A two-mode fiber long haul transmission system is simulated. The performances of both FDE and time-domain equalization (TDE) are verified and compared. The FDE approach reduces the computational complexity significantly compared to the TDE while maintaining the same performance. For a two-mode transmission of 2000 km, FDE decreases the complexity by a factor of as much as 77 compared with TDE at the expense of a large memory length of 2048 that may require higher hardware complexity. The dynamic response of the adaptive equalizer is simulated by using a mode scrambler. FDE achieves the same tracking speed as TDE. © 2012 IEEE.

Xi G.,Japan International Center for Materials Nanoarchitectonics | Xi G.,Chinese Academy of Inspection and Quarantine | Ye J.,Japan International Center for Materials Nanoarchitectonics | Ye J.,Tianjin University | And 4 more authors.
Journal of the American Chemical Society | Year: 2012

Metal/semiconductor hybrid materials of various sizes and morphologies have many applications in areas such as catalysis and sensing. Various organic agents are necessary to stabilize metal nanoparticles during synthesis, which leads to a layer of organic compounds present at the interfaces between the metal particles and the semiconductor supports. Generally, high-temperature oxidative treatment is used to remove the organics, which can extensively change the size and morphology of the particles, in turn altering their activity. Here we report a facile method for direct growth of noble-metal particles on WO 3 through an in situ redox reaction between weakly reductive WO 2.72 and oxidative metal salts in aqueous solution. This synthetic strategy has the advantages that it takes place in one step and requires no foreign reducing agents, stabilizing agents, or pretreatment of the precursors, making it a practical method for the controlled synthesis of metal/semiconductor hybrid nanomaterials. This synthetic method may open up a new way to develop metal-nanoparticle-loaded semiconductor composites. © 2012 American Chemical Society.

Li Y.N.,Tianjin University
IEEE Signal Processing Letters | Year: 2013

Robust and compact content representation is a fundamental problem in image processing. The recently proposed polar harmonic transforms (PHTs) have provided a set of powerful tools for image representation. However, two-dimensional transforms cannot handle color image in a holistic manner. To extend the nice properties of PHTs to color image processing, we generalize PHTs from the complex field to hypercomplex field in this letter, and quaternion polar harmonic transforms (QPHTs) are developed based on quaternion algebra. Furthermore, the properties of QPHTs are studied via quaternion computation, including the orthogonality of quaternion kernels, the relationships between different transforms and their rotation invariance. Experimental results reveal that compared with complex PHTs, the quaternion transforms can make a more compact and discriminative representation of color image. Moreover, QPHTs can well capture the chromatic features and exploit the inter-channel redundancies of color image. © 1994-2012 IEEE.

Zhang Z.,Tianjin University
Climate Policy | Year: 2015

The Chinese central government has approved seven pilot carbon trading schemes. These pilot regions have been deliberately selected to be at varying stages of development and are given considerable leeway to design their own schemes. These schemes have features in common, but vary considerably in their approach to issues such as the coverage of sectors, allocation of allowances, price uncertainty and market stabilisation, potential market power of dominated players, use of offsets, and enforcement and compliance. Our study finds that educating the covered entities, strictly enforcing compliance rules, ascribing allowances as financial assets and defining their valid duration, and including non-compliance in the credit record of non-complying entities are crucial to enabling active participation in carbon emissions trading. Moreover, the retrospective examination of the carbon trading pilots suggests that a national emissions trading scheme (ETS) should at least be based on uniform standards for measuring, reporting, and verification, the allocation of allowances, and the rules of compliance. Until a nationwide carbon market becomes fully functional after 2019, regional ETSs continue to function in parallel but those entities covered in the existing regional ETSs will be unconditionally integrated into a nationwide ETS if they meet the latter's threshold. Policy relevance The purpose of launching the seven carbon trading schemes and the reason why these seven pilot regions are given considerable leeway to design their own schemes are to enable China to develop a nationwide ETS with expanding geographical coverage and sectoral scope to complement the administrative means on which China, to date, has predominantly relied to achieve its increasingly stringent energy-saving and carbon intensity goals. This article discusses the lessons that carbon trading pilots have learned either from their own practice or other pilots in the first compliance year, as well as the good practice that the to-be-established national scheme could follow, and discusses the potential pathways for the evolution of regional pilot carbon trading schemes into a nationwide carbon trading scheme. Insights into the design, implementation, and compliance of China's carbon trading pilots and potential pathways help make these pilots work reliably and effectively and will smooth the transition from the pilots to a national ETS. © 2015 The Author(s). Published by Taylor and Francis.

Liu H.,University of Queensland | Du X.,Tianjin University | Xing X.,University of Science and Technology Beijing | Wang G.,University of Technology, Sydney | Qiao S.Z.,University of Queensland
Chemical Communications | Year: 2012

Highly ordered mesoporous Cr 2O 3 materials with high specific surface area and narrow pore size distribution were successfully prepared by a vacuum assisted impregnation method. Both 2-dimensional hexagonal and 3-dimensional cubic Cr 2O 3 mesoporous replicas from SBA-15 and KIT-6 templates exhibit enhanced performance for gas sensors and lithium ion batteries, compared to the bulk Cr 2O 3 counterpart.

Qian X.,Tianjin University | Qian X.,University of Kent | Yan Y.,University of Kent
IEEE Transactions on Instrumentation and Measurement | Year: 2012

Key parameters such as particle velocity, concentration of solid particles, and stability of pulverized fuel flow in fuel injection pipelines are useful to power plant operators to detect fuel supply problems at an early stage. This paper presents the use of a novel multichannel instrumentation system with circular and arc-shaped electrostatic sensor arrays for the online continuous measurement of mean and local characteristics of blended biomass flow. Experimental tests were conducted on a pneumatic conveying test rig under various flow conditions on both horizontal and vertical pipes. The biomass fuels tested include willow, wood, and bark. A ground grain (flour) was used to replicate a biomass of finer particles. The results suggest that, due to the physical differences between the constituent biomass fuels, the characteristics of the flow depend on the proportion of larger biomass particles in the blend. It is found that pure flour particles travel faster and carry more electrostatic charge than those of larger biomass particles. As more biomass particles are added to the flow, the overall velocity of the flow slows down, the electrostatic charge level decreases, and the flow becomes less stable compared to the pure flour flow. Particles in the vertical pipe are found to be more evenly distributed, and the particle velocity profile across the pipe cross section is more regular when compared to those in the horizontal pipe. © 2012 IEEE.

Wang X.,University of Hawaii at Manoa | Liu X.,Tianjin University | Wang G.,University of Hawaii at Manoa | Wang G.,Peking University
Journal of Integrative Plant Biology | Year: 2011

The overall goal of this work was to develop a saccharification method for the production of third generation biofuel (i.e. bioethanol) using feedstock of the invasive marine macroalga Gracilaria salicornia. Under optimum conditions (120 °C and 2% sulfuric acid for 30 min), dilute acid hydrolysis of the homogenized invasive plants yielded a low concentration of glucose (4.1 mM or 4.3 g glucose/kg fresh algal biomass). However, two-stage hydrolysis of the homogenates (combination of dilute acid hydrolysis with enzymatic hydrolysis) produced 13.8 g of glucose from one kilogram of fresh algal feedstock. Batch fermentation analysis produced 79.1 g EtOH from one kilogram of dried invasive algal feedstock using the ethanologenic strain Escherichia coli KO11. Furthermore, ethanol production kinetics indicated that the invasive algal feedstock contained different types of sugar, including C5-sugar. This study represents the first report on third generation biofuel production from invasive macroalgae, suggesting that there is great potential for the production of renewable energy using marine invasive biomass. © 2011 Institute of Botany, Chinese Academy of Sciences.

Cheng Y.C.,King Abdullah University of Science and Technology | Zhu Z.Y.,King Abdullah University of Science and Technology | Mi W.B.,Tianjin University | Guo Z.B.,King Abdullah University of Science and Technology | Schwingenschlogl U.,King Abdullah University of Science and Technology
Physical Review B - Condensed Matter and Materials Physics | Year: 2013

Using first-principles calculations, we propose a two-dimensional diluted magnetic semiconductor: monolayer MoS2 doped by transition metals. Doping of transition metal atoms from the IIIB to VIB groups results in nonmagnetic states, since the number of valence electrons is smaller or equal to that of Mo. Doping of atoms from the VIIB to IIB groups becomes energetically less and less favorable. Magnetism is observed for Mn, Fe, Co, Zn, Cd, and Hg doping, while for the other dopants from these groups it is suppressed by Jahn-Teller distortions. Analysis of the binding energies and magnetic properties indicates that (Mo,X)S2 (X=Mn, Fe, Co, and Zn) are promising systems to explore two-dimensional diluted magnetic semiconductors. © 2013 American Physical Society.

Jiang S.,East China Normal University | Yao Y.,East China Normal University | Chen Q.,East China Normal University | Chen Y.,Tianjin University
Macromolecules | Year: 2013

High-resolution 1H NMR has been used on the thermoresponsive hyperbranched polyethylenimines (HPEIs) modified with isobutyramide (IBAm) groups (HPEI-IBAm), to study the structure and dynamics of the macromolecules in aqueous solution before and after the phase transition. It shows that the HPEI-IBAm macromolecule having a high IBAm substitution degree has a clear phase transition in aqueous solution, whereas the HPEI-IBAm macromolecule having a low IBAm substitution degree does not. The different phase transition behaviors have been attributed to the content as well as the distribution of the IBAm groups in the macromolecules. In order to deepen the understanding of the phase transition, the hydrophobic-hydrophobic interaction inside the HPEI-IBAm macromolecules was investigated by monitoring the 1H-1H NOEs between the different hydrophobic groups. An enhanced hydrophobic- hydrophobic interaction was observed in the HPEI-IBAm macromolecule having a high IBAm substitution degree after the phase transition, which provides a new perspective for our understanding of the phase transition of the macromolecules in aqueous solution. By using PFG diffusion NMR, the weight distributions of the moving particles in the solution were monitored. The β parameter used in the PFG diffusion NMR, which reflects the change of the weight distributions of the moving particles in solution, has proved to be a good way to monitor the aggregation process of the moving particles in the solution. © 2013 American Chemical Society.

Tian L.,Tianjin University | Zhu C.,China Northwest Building Design Research Institute
Gongcheng Lixue/Engineering Mechanics | Year: 2013

Damage evaluation and protection technique of reinforced concrete RC column subjected to impulsive load are studied through numerical simulation of collision between a rigid ball and the RC column. On the basis of the bond-slip model for the RC column, a damage criterion is put forward to determine the damage degree of the RC column under impact based on the residual axial load-carrying capacity of the RC column. And correlativity between damage degree of the RC column and mass, initial velocity of rigid ball is studied qualitatively. Dynamic response and damage of RC columns before and after protection are analyzed, and the protective effects of strengthening with externally bonded steel plate and foamed aluminum are compared. The results indicate that: the damage degree increases faster than the mass and initial velocity of the rigid ball when the mass and initial velocity are in a low level, and the damage degree enhances fastest as the mass and initial velocity increase simultaneously; when the mass and initial velocity of rigid ball reach a certain value, the growth rate of damage degree will be lower than the mass and initial velocity's. Moreover, the two protective measures externally bonding steel plate and foamed aluminum can effectively reduce the mechanical response and damage degree of the RC columns; and the protection can also transfer the global failure mode of the RC column from bending-shear failure to bending failure.

Ma L.,Tianjin University of Science and Technology | Ma L.,University of St. Andrews | Liu J.,Tianjin University
Journal of Ethnopharmacology | Year: 2014

Materials and methods CBS (Conyza blinii saponin) is the total saponin of Conyza blinii H.Lév., which was obtained as described previously. We tested the protective activity of CBS against ethanol-induced ulcer. Thirty six rats were grouped randomly as 'NORMAL', 'CONTROL', 'MODEL', 'LOW DOSE', 'MEDIUM DOSE' and 'HIGH DOSE'. The 'NORMAL' group were rats with no pathological model established within it. The 'CONTROL' group was administrated with colloidal bismuth subcitrate, while 'MODEL' group was not given any active agents apart from absolute ethanol in order to obtain gastric ulcer model. The three 'DOSE' groups were treated with different concentrations of CBS (5, 10, 20 mg/mL) before administration followed by absolute ethanol. All rats were sacrificed after the experiment to acquire the gastric tissue. The ulcer index (UI), malondialdehyde (MDA) and superoxide dismutase (SOD) were measured to monitor the activity of CBS. Besides, the rat gastric tissue was made to paraffin section and stained using the Hematoxylin-Eosin (HE) method. The histopathology examination was carried out to examine CBS efficacy in terms of gastric mucous protection.Results We found that CBS had a profound protection activity against acute gastric ulcer induced by ethanol and this activity displayed a concentration-dependent manner. The efficacy of 10 and 20 mg/mL CBS was comparable with colloidal bismuth subcitrate (P<0.05). All three level of CBS tested were able to significantly reduce UI, MDA and enhance SOD level (P<0.05).Conclusions It was deduced that the mechanism for such activity would be anti-lipid peroxidation, facilitating free radicals clearance. In addition, histopathology examination of the gastric mucous membrane supported the same conclusion, that CBS can efficiently suppress the inflammatory reactions, bleeding and protect the gastric mucosa.Ethnopharmacological relevance Conyza blinii H.Lév., is a type of natural plant. Its dried overground section is used to treat infections and inflammations in traditional Chinese medicine. Triterpenoidal saponins have a wide range of bioactivities, for instance, anti-cancer, anti-virus and anti-anaphylaxis. Conyza blinii saponin (CBS), mainly composed of triterpenoidal saponins, is the total saponin of Conyza blinii H.Lév. It has been reported that CBS also has gastric mucous membrane protection activity. This study aims to test CBS's protective activity of gastric's mucous membrane against ethanol. This investigation may lead to the development of novel drug from natural products as anti-ulcer agent, or as gastric mucous protective against chemical damage. © 2014 Elsevier Ireland Ltd. All rights reserved.

Zeng H.,Nanjing University of Aeronautics and Astronautics | Zeng H.,CAS Hefei Institutes of Physical Science | Du X.-W.,Tianjin University | Singh S.C.,Dublin City University | And 4 more authors.
Advanced Functional Materials | Year: 2012

Laser ablation of solid targets in the liquid medium can be realized to fabricate nanostructures with various compositions (metals, alloys, oxides, carbides, hydroxides, etc.) and morphologies (nanoparticles, nanocubes, nanorods, nanocomposites, etc.). At the same time, the post laser irradiation of suspended nanomaterials can be applied to further modify their size, shape, and composition. Such fabrication and modification of nanomaterials in liquid based on laser irradiation has become a rapidly growing field. Compared to other, typically chemical, methods, laser ablation/irradiation in liquid (LAL) is a simple and "green" technique that normally operates in water or organic liquids under ambient conditions. Recently, the LAL has been elaborately developed to prepare a series of nanomaterials with special morphologies, microstructures and phases, and to achieve one-step formation of various functionalized nanostructures in the pursuit of novel properties and applications in optics, display, detection, and biological fields. The formation mechanisms and synthetic strategies based on LAL are systematically analyzed and the reported nanostructures derived from the unique characteristics of LAL are highlighted along with a review of their applications and future challenges. © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Zhu H.T.,Tianjin University
Probabilistic Engineering Mechanics | Year: 2013

An exponential-polynomial closure (EPC) method is introduced to solve the Fokker-Planck equation for the stationary multiple-peak probability density function (PDF) of the response of non-linear oscillators under Gaussian white noise. The EPC method uses Gaussian PDFs as a part of the weighting functions in the solution procedure. The Gaussian PDFs can be obtained by a standard equivalent linearization (EQL) method. This study considers the case that the EQL method gives multiple Gaussian PDFs. An improvement is proposed to make the weighting functions be independent of the choice of the Gaussian PDFs. To assess the effectiveness of the proposed method, a non-linear oscillator with a three-peak PDF of displacement is examined. Both low-level excitation and high-level excitation are considered. Comparison with the exact PDF solution shows that the improved EPC method can present a unique exact stationary PDF solution to the Fokker-Planck equation no matter which Gaussian PDF is adopted from the EQL method. © 2012 Elsevier Ltd.

Liu Y.,Tianjin University | Liu Y.,Chinese Institute of Urban Environment
Science of the Total Environment | Year: 2012

Knowledge of awareness, behavior and barriers to putting carbon management in place is particularly useful for policy-makers in providing favorable conditions in support of firms' climate change adaptation measures. According to unique data from in-depth interviews with firms from the most fossil fuel-intensive industries in Fujian, China, the present study indicated that the firms were relatively well informed of the knowledge and value of carbon management, and had a strong willingness to act. Nevertheless, there was no indication of actual behavior by these firms to enact carbon management, and a striking gap existed between awareness and behavior. The results also indicated the barriers, which were categorized into structural, regulatory, contextual and cultural. These barriers and their mutually reinforcing effects hampered the process of translating awareness into actual behavior. © 2012 Elsevier B.V.

Wang C.,Bohai University | He Q.,Hebei University | Chen D.,North China Electrical Power University | Hu Q.,Tianjin University
Information Sciences | Year: 2014

Attribute reduction has become an important step in pattern recognition and machine learning tasks. Covering rough sets, as a generalization of classical rough sets, have attracted wide attention in both theory and application. This paper provides a novel method for attribute reduction based on covering rough sets. We review the concepts of consistent and inconsistent covering decision systems and their reducts and we develop a judgment theorem and a discernibility matrix for each type of covering decision system. Furthermore, we present some basic structural properties of attribute reduction with covering rough sets. Based on a discernibility matrix, we develop a heuristic algorithm to find a subset of attributes that approximate a minimal reduct. Finally, the experimental results for UCI data sets show that the proposed reduction approach is an effective technique for addressing numerical and categorical data and is more efficient than the method presented in the paper [D.G. Chen, C.Z. Wang, Q.H. Hu, A new approach to attribute reduction of consistent and inconsistent covering decision systems with covering rough sets, Information Sciences 177(17) (2007) 3500-3518]. © 2013 Elsevier Inc. All rights reserved.

Chen D.,Tianjin University | Chen Z.,University of British Columbia | Grant E.,University of British Columbia
Analytical and Bioanalytical Chemistry | Year: 2011

Discrete wavelet transform (DWT) provides a well-established means for spectral denoising and baseline elimination to enhance resolution and improve the performance of calibration and classification models. However, the limitation of a fixed filter bank can prevent the optimal application of conventional DWT for the multiresolution analysis of spectra of arbitrarily varying noise and background. This paper presents a novel methodology based on an improved, second-generation adaptive wavelet transform (AWT) algorithm. This AWT methodology uses a spectrally adapted lifting scheme to generate an infinite basis of wavelet filters from a single conventional wavelet, and then finds the optimal one. Such pretreatment combined with a multivariate calibration approach such as partial least squares can greatly enhance the utility of Raman spectroscopy for quantitative analysis. The present work demonstrates this methodology using two dispersive Raman spectral data sets, incorporating lactic acid and melamine in pure water and in milk solutions. The results indicate that AWT can separate spectral background and noise from signals of interest more efficiently than conventional DWT, thus improving the effectiveness of Raman spectroscopy for quantitative analysis and classification. © 2011 Springer-Verlag.

Lin W.,Tianjin University
Applied Physics A: Materials Science and Processing | Year: 2011

A novel durable substrate has been prepared for surface-enhanced Raman spectroscopy (SERS). The substrate is fabricated by reduction of silver nitrate using poly(vinyl pyrrolidone) (PVP) polymer as stabilizers. The SERS-active particles are based on poly(methylmethacrylate) (PMMA) materials, producing stable and optically translucent substrates. The stability of silver particles on the substrate was demonstrated by characterizing the localized surface plasmon resonance (LSPR) band of the elemental silver particles. The SERS activity was evaluated by detecting the signal from Raman probe molecules, Rhodamine 6G (R6G). This plastic substrate material is easy to prepare, inexpensive, and sturdy for SERS applications. © 2010 Springer-Verlag.

Zhou G.,North China Electrical Power University | Zhang Y.,Tianjin University
Applied Thermal Engineering | Year: 2012

Inlet pressure fluctuations were found during the experiments for coiled adiabatic capillary tubes in a one-pass-through type test facility. The fluctuation takes place when the inlet temperature rapidly changes from one point to another. Measured temperature distribution along the tube length showed that this phenomenon may be caused by the variation of flash point location in the capillary tube which leads to the pressure variation wave propagating upstream. Further experiments showed that the pressure fluctuation for coiled capillary tubes is much more prominent than for straight ones; the inlet pressure fluctuation is weak for small coil-diameter capillary tubes; with the increasing of the preset inlet pressure and decreasing of target inlet temperature, the fluctuation amplitude decreases; the pressure fluctuation amplitude at the inlet of parallel coiled capillary tubes is much lower than that of the single one and it needs less time to be stabilized which indicates the advantages of using parallel capillary tubes. The inlet pressure fluctuation in an actual air-conditioner system is found weaker than in the one-pass-through test facility. © 2011 Elsevier Ltd. All rights reserved.

Liu W.,Tianjin University | Liu W.,Shenzhen University | Niu H.,Shenzhen University
Physical Review A - Atomic, Molecular, and Optical Physics | Year: 2011

We provide an approach to significantly break the diffraction limit in coherent anti-Stokes Raman scattering (CARS) microscopy via an additional probe-beam-induced photon depletion (APIPD). The additional probe beam, whose profile is doughnut shaped and whose wavelength is different from the Gaussian probe beam, depletes the phonons to yield an unwanted anti-Stokes signal within a certain bandwidth at the rim of the diffraction-limited spot. When the Gaussian probe beam that follows immediately arrives, no anti-Stokes signal is generated in this region, resembling stimulated emission depletion (STED) microscopy, and the spot-generating useful anti-Stokes signals by this beam are substantially suppressed to a much smaller dimension. Scanning the spot renders three-dimensional, label-free, and chemically selective CARS images with subdiffraction resolution. Also, resolution-enhanced images of the molecule, specified by its broadband even-total CARS spectral signals not only by one anti-Stokes signal for its special chemical bond, can be obtained by employing a supercontinuum source. © 2011 American Physical Society.

Han X.,Tianjin University
International Journal of Advanced Manufacturing Technology | Year: 2015

Machining technology about silicate glass has been developed very fast over recent years due to the growing industrial demand of higher machining accuracy and better surface quality of optical elements while the nature of hard and brittle materials makes it difficult to acquire damage-free and ultrasmooth surface. Molecular dynamics method (MD) provides a promising approach for constructing an efficient model to describe the tool–workpiece interaction, serves as a predicting simulation tool in analyzing the complicated surface generation mechanism, and is employed in this research to study the mechanical polishing of glass and surface integrity. The results show that some particles change the substrate surface morphology by means of elastic/plastic deformation and finally being left at the top of a polished surface, and it is difficult to be removed because of the strong adhesion force. Three stages are involved in the particle adhesion process: firstly, molecular interaction force dominated the approaching stage but not contact stage; secondly, the adhesion and the resistance of deformation will gradually occupy a dominant position upon the interface adsorption and bulk deformation; and the contact area is gradually stabilized and the body deflection begins to increase and the relative stable structure is generated. A different dynamic trajectory is observed with the increasing of impacting speed and abrasive particle abruptly jumping to another point although the joint has already been generated in the initial stage. © 2015 Springer-Verlag London

Kong X.,Liaocheng University | Chen L.,Tianjin University
Applied Catalysis A: General | Year: 2014

With benzaldehyde as a model compound, the hydrogenation of aromatic aldehydes to corresponding benzyl alcohols was investigated in a fixed-bed reactor. Co/γ-Al2O3 doped with a amount of SiO 2 displayed excellent catalytic performance for this reaction, Co/γ-Al2O3 is modified by SiO2 in two ways, the strong interaction between metal oxide and support is obviously reduced, and also a large number of acid sites are diminished on the catalyst. The first aspect apparently facilitated the reduction of metal oxide, and improved the hydrogenation activity of the catalyst; while the second aspect greatly inhibited the hydrogenolysis of the CO bond, and thus increased the selectivity toward benzyl alcohol. © 2014 Elsevier B.V.

Zhao J.-X.,Tianjin University
Computers and Mathematics with Applications | Year: 2015

In this paper, we investigate a discretized version of an elliptic optimal control problem which is presented by Stadler (2009). An alternating direction method is proposed to solve this problem and demonstrated as globally convergent. This class of methods is attractive due to its simplicity and thus is adequate for solving large-scale problems. The preliminary numerical results present the efficiency of the proposed method. © 2015 Elsevier Ltd.

Li Z.Z.,Tianjin University
Zhen ci yan jiu = Acupuncture research / [Zhongguo yi xue ke xue yuan Yi xue qing bao yan jiu suo bian ji] | Year: 2012

To observe the changes of thoracic duct lymph volume and the contents of histamine (HA), 5-hydroxytryptamine (5-HT), etc. in the lymph after acupuncture or thermal acupuncture interventions, in order to investigate the effect of lymphatic system in transmitting acupuncture and moxibustion signals. A total of 45 male Wistar rats were randomly divided into control group, acupuncture group, and thermal acupuncture (acupuncture with the needle warmed by burning moxa) group (n = 15/group). The rat thoracic duct lymphatic fistula model was replicated. Acupuncture or thermal acupuncture was applied to "Zusanli" (ST 36), and the changes of thoracic duct lymph volume and the concentrations of HA, 5-HT in the lymph were observed. Compared with the control group, the thoracic duct lymph volume in acupuncture group and thermal acupuncture group were obviously increased (P < 0.05), while the concentrations of lymph HA and 5-HT in both acupuncture and thermal acupuncture groups had no significant changes (P > 0.05). Both acupuncture and thermal acupuncture interventions can increase the thoracic duct lymph volume, but have no effects on lymph HA and 5-HT contents in normal rats.

Chemical mechanical planarization (CMP) has become the process of choice for surface global planarization for materials surfaces in the fabrication of advanced multilevel integrated circuits (ICs) in microelectronic industry. The surface planarization in the CMP is mainly realized by the tribology behavior of nanoparticles. The suspending abrasive particles impinge on the surface at some velocity and angle thus imparting energy to the surface, resulting in strain, weakened bonds, and eventually material removal. Large-scale classical molecular dynamic (MD) simulation of interaction among nanoparticles and solid surface has been carried out to investigate the physical essence of fluid-based surface planarization process. The investigation shows that the plastic deformation plays an important role in this nanoscale wear process while the contribution of dislocations to the yield stress becomes insignificant. The depth of wear is gradually decreased which makes the fluid-based wear cannot realize the global surface planarization by itself. The abrasive wear process leads to characteristic surface topography running in the same direction as the sliding motion while the adhesive wear leads to the atoms of the substrate materials adhere to the opposing surface. The adhesion wear plays an important role at lower moving speed while the abrasive wear dominates the wear process at higher moving speed which means the moving speed is one of the key factors that influence the particle wear mechanism at the nanometer scale. Different tribology behavior involved in the CMP indicates that the final surface planarization is accomplished by the synergetic effect of different wear mechanism. © 2011 American Institute of Physics.

Zhu H.T.,Tianjin University
Physica A: Statistical Mechanics and its Applications | Year: 2014

This paper proposes a solution procedure for obtaining an approximate probability density function (PDF) of the response of vibro-impact Duffing systems with a unilateral non-zero offset barrier. The impact model is used with classical impacts with instantaneous velocity jumps and the excitation is modelled by a zero mean stationary Gaussian white noise. First the original vibro-impact system is converted into a system without barriers by adopting the Zhuravlev non-smooth coordinate transformation. Second the PDF of the converted system is obtained by solving the Fokker-Planck (FP) equation with the exponential-polynomial closure (EPC) method. Last the PDF of the original system is achieved using the well-established methodology on seeking the PDF distribution of a function of a random variable. A further parametric study is also conducted to evaluate the effectiveness of the proposed solution procedure. Comparison with the simulated result shows that when lightly inelastic impacts occur (i.e, the restitution coefficient is very close to 1.0), the technique of the Zhuravlev non-smooth coordinate transformation is feasible. The transformed system can adequately represent the original system. Consequently the EPC method can provide a good approximate PDF solution. The tail region of the PDF is also approximated well. The analysis further shows that the non-zero offset significantly affects the shape of the PDF distribution of displacement. © 2014 Elsevier B.V. All rights reserved.

Jin L.,Tianjin University | Dai B.,Shihezi University
Applied Surface Science | Year: 2012

Vermiculite was treated by sulfuric or nitric acid aqueous solutions with different concentration. These modified materials as the promising supports, were used to immobilize TiO 2. TiO 2 was prepared by the precursor, which was obtained by substituting partly isopropyl alcohol with Cl - in titanium chloride {[Ti(IV)(OR) nCl m] (n = 2-3, m = 4 - n)}. The TiO 2/vermiculite composites were characterized by X-ray diffraction, scanning electron microscopy, and the nitrogen absorption. Their photocatalytic activity was evaluated by removal of methylene blue (MB). The pure anatase type crystalline phase was well deposited on the supports. The concentrations of acid for treatment had a significant influence on pore sizes and surface area of vermiculite. The treatment process changed microstructure of vermiculite, modified its characteristics, and farther improved the catalytic activity and absorption capacity of TiO 2/vermiculite composites. The treatment effect of nitric acid was superior to that of sulfuric acid. © 2011 Elsevier B.V. All rights reserved.

Zhou G.,North China Electrical Power University | Zhang Y.,Tianjin University
Applied Energy | Year: 2010

This paper experimentally investigated the system performance of a split-type air conditioner matching with different coiled adiabatic capillary tubes for HCFC22 and HC290. Experiments were carried out in a room-type calorimeter. The results have shown that (1) similar cooling effects can be achieved by matching various capillary tubes of different inner diameters; (2) parallel capillary tubes presented better system performance and flow stability with weaker inlet pressure fluctuations than the single capillary tube; (3) with the coil diameter of the capillary tube increasing from 40 mm to 120 mm, the mass flow rate tended to increase slightly. But the cooling capacity, input power and energy efficiency ratio (EER) did not show evident tendency of change; (4) the refrigerant charge and mass flow rate for HC290 were only 44% and 47% of that for HCFC22, respectively, due to the much lower density. And HC290 had 4.7-6.7% lower cooling capacity and 12.1-12.3% lower input power with respect to HCFC22. However, the EER of HC290 can be 8.5% higher than that of HCFC22, which exhibits the advantage of using HC290. In addition, the experimental uncertainties were analyzed and some application concerns of HC290 were discussed. © 2009 Elsevier Ltd. All rights reserved.

Song Y.-L.,Tianjin University
Wuli Xuebao/Acta Physica Sinica | Year: 2010

The FitzHugh-Nagumo neuron model driven by a harmonic noise is investigated, whose dynamic behaviours are influenced by the frequency and the damping parameters of noise. The spikes train varies with these two parameters changing. The FitzHugh-Nagumo neuron has resonance characteristic and exhibits stronger response to noise with a given frequency. Undernoise with this frequency parameter, the spikes train is more regular and the coefficient of coherent resonance reaches the minimum. The larger the damping parameter of the noise is, the more the different ingredients are, thus the synchronization between neuron and noise becomes more imperfect and the coefficient of coherent resonance is larger. ©2010 Chin.Phys.Soc.

This paper investigates the probability density function (PDF) of multi-degree-of-freedom nonlinear systems excited by nonzero mean Poisson impulses. The PDF solution is governed by the Kolmogorov–Feller equation which is also called the generalized Fokker–Planck–Kolmogorov (FPK) equation. First the high-dimensional generalized FPK equation is reduced to a low-dimensional equation by a state-space-split method. The reduced FPK equation is further solved by an exponential-polynomial closure method. In numerical analysis, a ten-degree-of-freedom Duffing system is further investigated under nonzero mean Poisson impulses. The PDF distribution of impulse amplitudes is adopted with either a nonzero mean Gaussian distribution or a nonzero mean Rayleigh distribution. Comparison with the simulated results shows that the proposed solution procedure is effective to obtain a satisfactory PDF solution, especially in the tail region. The nonzero mean PDF of displacement is formulated due to nonzero mean Poisson impulses. The obtained PDF of displacement is not symmetrically distributed about its mean. © 2015, Springer-Verlag Wien.

Wang B.,Arizona State University | Wang J.,Arizona State University | Wang J.,Tianjin University | Meldrum D.R.,Arizona State University
Frontiers in Microbiology | Year: 2012

Cyanobacteria and algae are becoming increasingly attractive cell factories for producing renewable biofuels and chemicals due to their ability to capture solar energy and CO2 and their relatively simple genetic background for genetic manipulation. Increasing research efforts from the synthetic biology approach have been made in recent years to modify cyanobacteria and algae for various biotechnological applications. Inthisarticle, wecritically review recent progresses in developing genetic tools for characterizing or manipulating cyanobacteria and algae, the applications of genetically modified strains for synthesizing renewable products such as biofuels and chemicals. In addition, the emergent challenges in the development and application of synthetic biology for cyanobacteria and algae are also discussed. © 2012 Wang, Wang, Zhang and Meldrum.

Zhao B.,Zhejiang Electrical Power Test and Research Institute | Zhang X.,Zhejiang Electrical Power Test and Research Institute | Chen J.,Tianjin University
IEEE Transactions on Power Systems | Year: 2012

The paper presents an integrated microgrid laboratory system with a flexible and reliable multimicrogrid structure; it contains multiple distributed generation systems and energy storage systems and integrates with a diesel generator that serves as a back-up power source and flywheel energy storage for fast balancing to provide uninterruptible power-supply services in cooperation with the diesel generator. The microgrid system, by adopting the master-slave control strategy, can be transited flexibly between grid-connected and islanded modes and can be disconnected from the utility when a fault occurs or the power quality falls below specified standards. The developed bi-directional inverter which is applied in the system plays an important role. The small microgrids of this system are intended to operate separately or in the form of one large microgrid with a certain switch status. Furthermore, experiments on control, protection, and other technologies have been carried out. The results show that the operation conditions meet the related IEEE Standard 1547 and power quality requirements. The integrated microgrid laboratory system is able to operate stably and reliably under different conditions, including mode transition and fault events. © 1969-2012 IEEE.

Yan K.,Lakehead University | Lafleur T.,Lakehead University | Liao J.,Tianjin University
Journal of Nanoparticle Research | Year: 2013

Different loading of palladium (Pd) nanoparticles were successfully fabricated on multi-walled carbon nanotubes using Pd acetylacetonate as the precursor via a simple liquid impregnation method. The crystal phase, morphology, textural structure and the chemical state of the resulting Pd nanoparticles (Pd/CNT) catalysts were studied and the characterization results indicated that the uniform dispersion of small Pd nanoparticles with the size range of 1.0-4.5 nm was achieved. The synthesized Pd/CNT catalysts exhibited efficient performance for the catalytic hydrogenation of biomass-derived levulinic acid into biofuel γ-valerolactone. In comparison with the commercial 5 wt% Pd/C and the 5 wt% Pd/CNT catalyst prepared by Pd nitrate precursor, much higher activities were achieved, whereas the biofuel γ-valerolactone was highly produced with 56.3 % yield at 57.6 % conversion of levulinic acid on the 5 wt% Pd/CNT catalyst under mild conditions. The catalyst developed in this work may be a good candidate for the wide applications in the hydrogenation. © 2013 Springer Science+Business Media.

Zhu H.T.,Tianjin University
Journal of the Acoustical Society of America | Year: 2012

This paper studies the stationary probability density function (PDF) of the response of multi-degree-of-freedom nonlinear systems under external independent Poisson white noises. The PDF is governed by the high-dimensional generalized Fokker-Planck-Kolmogorov (FPK) equation. The state-space-split (3S) method is adopted to reduce the high-dimensional generalized FPK equation to a low-dimensional equation. Subsequently, the exponential-polynomial closure (EPC) method is further used to solve the reduced FPK equation for the PDF solution. Two illustrative examples are presented to examine the accuracy of the 3S-EPC solution procedure. One example involves a two-degree-of-freedom coupled nonlinear system. The other example is concerned with a ten-degree-of-freedom system with cubic terms in displacement. A Monte Carlo simulation is also performed for simulating the PDF solution of the response. The comparison with the simulated result shows that the 3S-EPC solution procedure can provide satisfactory PDF solutions. The good agreement is also observed in the tail regions of the PDF solutions. © 2012 Acoustical Society of America.

Bao H.,Ben - Gurion University of the Negev | Hatzor Y.H.,Ben - Gurion University of the Negev | Huang X.,Tianjin University
Rock Mechanics and Rock Engineering | Year: 2012

Viscous boundaries are widely used in numerical simulations of wave propagation problems in rock mechanics and rock engineering. By using such boundaries, reflected waves from artificial boundaries can be eliminated; therefore, an infinite domain can be modeled as a finite domain more effectively and with a much greater accuracy. Little progress has been made, thus far, with the implementation and verification of a viscous boundary in the numerical, discrete element, discontinuous deformation analysis (DDA) method. We present in this paper a new viscous boundary condition for DDA with a higher absorbing efficiency in comparison to previously published solutions. The theoretical derivation of the new viscous boundary condition for DDA is presented in detail, starting from first principles. The accuracy of the new boundary condition is verified using a series of numerical benchmark tests. We show that the new viscous boundary condition works well with both P waves as well as S waves. © Springer-Verlag 2012.

Zhao X.,Tianjin University
Advances in Intelligent and Soft Computing | Year: 2012

This paper reviews the research on service quality of higher education and the successful experience of foreign student satisfaction measurement. Firstly, the author introduces the global trend and intensively competitive situation of higher education service. The important function of student satisfaction survey in higher education management is also mentioned. Secondly, the related notions of service quality and student satisfaction are discussed. Then, the qualitative and quantitative methods widely used in student satisfaction assessment are compared. Finally, the conclusions obtained by present research are summarized. © 2012 Springer-Verlag Berlin Heidelberg.

Zhang Z.H.,Hong Kong Polytechnic University | Zhang Z.H.,National University of Singapore | Cheung C.S.,Hong Kong Polytechnic University | Yao C.D.,Tianjin University
Fuel | Year: 2013

This study is aimed to investigate the effects of fumigation methanol on the combustion and particulate emissions of a diesel engine under different engine loads and fumigation level. Experiments were performed on a 4-cylinder direct injection diesel engine operating at the engine speed of 1920 rev/min with five engine loads. The combustion characteristic analysis indicates that with fumigation methanol, the maximum cylinder pressure decreases at low to medium engine loads but increases at high engine load. Fumigation methanol increases the peak heat release rate and ignition delay but does not significantly change the combustion duration. The fumigation method results in a significant decrease in particulate mass and number concentrations from medium to high engine loads, due to the increase of fuel burned in the premixed mode and a reduction of diesel fuel involved. Fumigation methanol also slightly decreases the fraction of accumulation mode particles and thus the particulate geometric mean diameter (GMD). © 2013 Elsevier Ltd. All rights reserved.

Zhao Y.,Zhejiang University | Xiang X.,Zhejiang University | Li W.,Zhejiang University | He X.,Zhejiang University | And 2 more authors.
IEEE Transactions on Power Electronics | Year: 2013

An advanced symmetrical voltage quadrupler rectifier (SVQR) is derived in this paper to serve as the secondary rectification topology, which helps to extend the converter voltage gain and reduce the output diode voltage stresses. The output voltage is four times of the conventional full-bridge voltage rectifier with the same transformer ratio, which benefits to reduce the turns ratio of the transformer and decrease the parasitic parameters. Also, low voltage-rated diodes with high switching performance can be applied to improve the efficiency. Meanwhile, all the diodes in SVQR have the same voltage and current stresses, which simplifies the thermal design. Furthermore, two output electrolytic capacitors are connected in series to share the high output voltage, and the voltage balance can be realized naturally without any additional voltage-sharing scheme. A clear picture is made in this paper to give a general framework and universal applications for the derived SVQRs for high step-up and high output voltage conversion systems. A dual boost converter is used as an example to demonstrate the clear advantages of the derived SVQRs. © 2012 IEEE.

Li Y.,Tianjin University | Wang A.,Peking University
Journal of Lightwave Technology | Year: 2010

The design of bandgap-engineered all-solid photonic bandgap fibers based on a broken-ring structure is investigated in detail. Both density of states maps and Bloch mode field distributions are used to show how the bandgap structure can be engineered and a higher-order gap be greatly expanded by replacing the high-index germanium-doped rod in a repeating cell with a ring of several individual high-index rods. The strategy is that both the azimuthal and radial orders of the cladding LP modes can be controlled by the broken-ring parameters. In particular, the rod number determines the highest azimuthal order of the LP mode that is less affected by the broken-ring, and the bandgap width is largely affected by the rod size. The result of bandgap engineering is that the higher-order bandgap can be utilized to design all-solid photonic bandgap fibers with very broad transmission windows of 488 nm and 944 nm centered at 800 nm and 1550 nm, respectively, and with typical normal-zero-anomalous dispersion profiles. © 2006 IEEE.

Chen Z.,University of Wurzburg | Chen Z.,Tianjin University | Fimmel B.,University of Wurzburg | Wurthner F.,University of Wurzburg
Organic and Biomolecular Chemistry | Year: 2012

A series of six perylene bisimides (PBIs) with hydrophilic and hydrophobic side chains at the imide nitrogens were applied for a comparative study of the solvent and structural effects on the aggregation behaviour of this class of dyes. A comparison of the binding constants in tetrachloromethane at room temperature revealed the highest binding constant of about 105 M -1 for a PBI bearing 3,4,5-tridodecyloxyphenyl substituents at the imide nitrogens, followed by 3,4,5-tridodecylphenyl and alkyl-substituted PBIs, whereas no aggregation could be observed in the accessible concentration range for PBIs equipped with bulky 2,6-diisopropylphenyl substituents at the imide nitrogens. The aggregation behaviour of three properly soluble compounds was investigated in 17 different solvents covering a broad polarity range from nonpolar n-hexane to highly polar DMSO and water. Linear free energy relationships (LFER) revealed a biphasic behaviour between Gibbs free energies of aggregation and common empirical solvent polarity scales indicating particularly strong π-π stacking interactions in nonpolar aliphatic and polar alcoholic solvents whilst the weakest binding is observed in dichloromethane and chloroform. Accordingly, PBI aggregation is dominated by electrostatic interactions in nonpolar solvents and by solvophobic interactions in protic solvents. In water, the aggregation constant is increased far beyond LFER expectations pointing at a pronounced hydrophobic effect. © 2012 The Royal Society of Chemistry.

Yu W.,Tianjin University
Expert Systems with Applications | Year: 2016

With the evolution of geographic information capture and the emergency of volunteered geographic information, it is getting more important to extract spatial knowledge automatically from large spatial datasets. Spatial co-location patterns represent the subsets of spatial features whose objects are often located in close geographic proximity. Such pattern is one of the most important concepts for geographic context awareness of location-based services (LBS). In the literature, most existing methods of co-location mining are used for events taking place in a homogeneous and isotropic space with distance expressed as Euclidean, while the physical movement in LBS is usually constrained by a road network. As a result, the interestingness value of co-location patterns involving network-constrained events cannot be accurately computed. In this paper, we propose a different method for co-location mining with network configurations of the geographical space considered. First, we define the network model with linear referencing and refine the neighborhood of traditional methods using network distances rather than Euclidean ones. Then, considering that the co-location mining in networks suffers from expensive spatial-join operation, we propose an efficient way to find all neighboring object pairs for generating clique instances. By comparison with the previous approaches based on Euclidean distance, this approach can be applied to accurately calculate the probability of occurrence of a spatial co-location on a network. Our experimental results from real and synthetic data sets show that the proposed approach is efficient and effective in identifying co-location patterns which actually rely on a network. © 2015 Elsevier Ltd. All rights reserved.

Geng X.,Tianjin University
Nan fang yi ke da xue xue bao = Journal of Southern Medical University | Year: 2013

To evaluate the reliability of diagnostic ultrasound-based temperature and elasticity imaging during radiofrequency ablation (RFA) through ex vivo experiments. Procine liver samples (n=7) were employed for RFA experiments with exposures of different power intensities (10 and 50w). The RFA process was monitored by a diagnostic ultrasound imager and the information were postoperatively captured for further temperature and elasticity image analysis. Infrared thermometry was concurrently applied to provide temperature change calibration during the RFA process. Results from this study demonstrated that temperature imaging was valid under 10 W RF exposure (r=0.95), but the ablation zone was no longer consistent with the reference infrared temperature distribution under high RF exposures. The elasticity change could well reflect the ablation zone under a 50 W exposure, whereas under low exposures, the thermal lesion could not be well detected due to the limited range of temperature elevation and incomplete tissue necrosis. Diagnostic ultrasound-based temperature and elastography is valid for monitoring thr RFA process. Temperature estimation can well reflect mild-power RF ablation dynamics, whereas the elastic-change estimation can can well predict the tissue necrosis. This study provide advances toward using diagnostic ultrasound to monitor RFA or other thermal-based interventions.

Ji C.,Queen Mary, University of London | Ji C.,Tianjin University | Munjiza A.,Queen Mary, University of London | Williams J.J.R.,Queen Mary, University of London
Journal of Computational Physics | Year: 2012

We present a novel iterative immersed boundary (IB) method in which the body force updating is incorporated into the pressure iterations. Because the body force and pressure are solved simultaneously, the boundary condition on the immersed boundary can be fully verified. The computational costs of this iterative IB method is comparable to those of conventional IB methods. We also introduce an improved body force distribution function which transfers the body force in the discrete volume of IB points to surrounding Cartesian grids totally. To alleviate the demanding computational requirements of a full-resolved direct numerical simulation, a wall-layer model is presented. The accuracy and capability of the present method is verified by a variety of two- and three-dimensional numerical simulations, ranging from laminar flow past a cylinder and a sphere to turbulent flow around a cylinder. The improvement of the iterative IB method is fully demonstrated and the influences of different body force distribution strategies is discussed. © 2011 Elsevier Inc.

Dai J.,Nanjing Southeast University | Dai J.,Jiangsu University of Science and Technology | Xu C.X.,Nanjing Southeast University | Sun X.W.,Nanyang Technological University | Sun X.W.,Tianjin University
Advanced Materials | Year: 2011

The whispering gallery mode (WGM) lasing and microphotoluminescence from a hexagonal ZnO microrod are investigated. The hexagonal ZnO microrod is integrated on a p-GaN substrate to fabricate a heterostructured microlaser diode and the electrically pumped WGM lasing from the diode is realized. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Chen R.,Nanyang Technological University | Ling B.,Nanyang Technological University | Sun X.W.,Nanyang Technological University | Sun X.W.,Tianjin University | Sun H.D.,Nanyang Technological University
Advanced Materials | Year: 2011

High-quality ZnO microdisks are prepared by a vapor phase transport method. The ZnO microdisks have perfect hexagonal shape and exhibit strong excitonic lasing under optical excitation at room temperature. The observed lasing modes match well with whispering gallery modes. © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Gong X.J.,Tianjin University
Journal of integrative bioinformatics | Year: 2012

The expression and regulation of genes in different tissues are fundamental questions to be answered in biology. Knowledge enrichment analysis for tissue specific (TS) and housekeeping (HK) genes may help identify their roles in biological process or diseases and gain new biological insights. In this paper, we performed the knowledge enrichment analysis for 17,343 genes in 84 human tissues using Gene Set Enrichment Analysis (GSEA) and Hypergeometric Analysis (HA) against three biological ontologies: Gene Ontology (GO), KEGG pathways and Disease Ontology (DO) respectively. The analyses results demonstrated that the functions of most gene groups are consistent with their tissue origins. Meanwhile three interesting new associations for HK genes and the skeletal muscle tissue genes are found. Firstly, Hypergeometric analysis against KEGG database for HK genes disclosed that three disease terms (Parkinson's disease, Huntington's disease, Alzheimer's disease) are intensively enriched. Secondly, Hypergeometric analysis against the KEGG database for Skeletal Muscle tissue genes shows that two cardiac diseases of "Hypertrophic cardiomyopathy (HCM)" and "Arrhythmogenic right ventricular cardiomyopathy (ARVC)" are heavily enriched, which are also considered as no relationship with skeletal functions. Thirdly, "Prostate cancer" is intensively enriched in Hypergeometric analysis against the disease ontology (DO) for the Skeletal Muscle tissue genes, which is a much unexpected phenomenon.

Stress corrosion cracks (SCC) in low-pressure steam turbine discs are serious hidden dangers to production safety in the power plants, and knowing the orientation and depth of the initial cracks is essential for the evaluation of the crack growth rate, propagation direction and working life of the turbine disc. In this paper, a method based on phased array ultrasonic transducer and artificial neural network (ANN), is proposed to estimate both the depth and orientation of initial cracks in the turbine discs. Echo signals from cracks with different depths and orientations were collected by a phased array ultrasonic transducer, and the feature vectors were extracted by wavelet packet, fractal technology and peak amplitude methods. The radial basis function (RBF) neural network was investigated and used in this application. The final results demonstrated that the method presented was efficient in crack estimation tasks.

Du J.-L.,Tianjin University
Chinese Physics B | Year: 2010

The current form of Tsallis distribution for a Hamiltonian system with an arbitrary potential is found to represent a simple isothermal situation. This paper finds that the q-exponential of a sum can be applied as the product of the q- exponential based on the probabilistically independent postulate employed in nonextensive statistical mechanics. Under this framework, a new form of Tsallis distribution is suggested. It shows that the new form of Tsallis distribution can supply the statistical description for the nonequilibrium dynamical property of the Hamiltonian system governed by an arbitrary potential, and it is found to be one potential statistical distribution for the dark matter. © 2010 Chinese Physical Society and IOP Publishing Ltd.

Boffety M.,University Paris - Sud | Hu H.,Tianjin University | Goudail F.,University Paris - Sud
Optics Letters | Year: 2014

Polarimetric imaging is often performed using light with a narrow spectrum for the sake of polarization measurement accuracy. However, due to the use of narrowband filters, this reduces the amount of light entering the system and thus the signal-to-noise ratio. This may not be the best choice for target detection applications, where a high target contrast is required rather than polarimetric accuracy. We address contrast optimization for broadband passive polarimetric imaging. We show through simulation and experiments that polarimetric contrast can be significantly increased by broadening the spectrum of analyzed light. In addition, we show that the contrast can be optimized by taking into account the spectral dependence of the scene and of the polarization analysis devices. © 2014 Optical Society of America.

Dai H.-H.,City University of Hong Kong | Cai Z.,Tianjin University
Journal of the Mechanics and Physics of Solids | Year: 2012

In the experiments on stress-induced phase transitions in SMA strips, several interesting instability phenomena have been observed, including a necking-type instability (associated with the stress drop), a shear-type instability (associated with the inclination of the transformation front) and an orientation instability (associated with the switch of the inclination angle). In order to shed more lights on these phenomena, in this paper we conduct an analytical study. We consider the problem in a three-dimensional setting, which implies that one needs to study the difficult problem of solution bifurcations of high-dimensional nonlinear partial differential equations. By using the smallness of the maximum strain, the thickness and width of the strip, we use a methodology, which combines series expansions and asymptotic expansions, to derive the asymptotic normal form equations, which can yield the leading-order behavior of the original three-dimensional field equations. An important feature of the second normal form equation is that it contains a turning point for the localization (necking) solution of the first equation. It is the presence of such a turning point which causes the inclination of the phase transformation front. The WKB method is used to construct the asymptotic solutions, which can capture the shear instability and the orientation instability successfully. Our analytical results reveal that the inclination of the transformation front is a phenomenon of localization-induced buckling (or phase-transition-induced buckling as the localization is caused by the phase transition). Due to the similarities between the development of the Luders band in a mild steel and the stress-induced transformations in a SMA, the present results give a strong analytical evidence that the former is also caused by macroscopic effects instead of microscopic effects. Our analytical results also reveal more explicitly the important roles played by the geometrical parameters. © 2011 Elsevier Ltd. All rights reserved.

Song J.,Nanyang Technological University | Chen Y.,Tianjin University | Lu G.,Nanyang Technological University
International Journal of Mechanical Sciences | Year: 2013

Patterned windows are introduced to the thin-walled square tubes to reduce the weight while maintaining the mechanical property of the original tube. The topological pattern design is studied under axial compressing condition. Experimental results show that these windowed tubes have enhanced crushing performance over the conventional tube, with 63% as the maximum reduction in the initial peak load and 54% as the maximum increase in the specific energy absorption. Parametric study is conducted by using a finite element analysis to investigate the effect of the size of windows on tubes' collapse characteristics. Three collapse modes, the symmetric, extensional and diamond modes, are distinguished. Tubes collapsing in the diamond mode perform less well in terms of both the energy absorption and SEA, while those with the symmetric or extensional mode generally show an increase in SEA. © 2012 Elsevier Ltd. All rights reserved.

Copy-move is one of the most commonly used image tampering operation, where a part of image content is copied and then pasted to another part of the same image. In order to make the forgery visually convincing and conceal its trace, the copied part may subject to post-processing operations such as rotation and blur. In this paper, we propose a polar cosine transform and approximate nearest neighbor searching based copy-move forgery detection algorithm. The algorithm starts by dividing the image into overlapping patches. Robust and compact features are extracted from patches by taking advantage of the rotationally-invariant and orthogonal properties of the polar cosine transform. Potential copy-move pairs are then detected by identifying the patches with similar features, which is formulated as approximate nearest neighbor searching and accomplished by means of locality-sensitive hashing (LSH). Finally, post-verifications are performed on potential pairs to filter out false matches and improve the accuracy of forgery detection. To sum up, the LSH based similar patch identification and the post-verification methods are two major novelties of the proposed work. Experimental results reveal that the proposed work can produce accurate detection results, and it exhibits high robustness to various post-processing operations. In addition, the LSH based similar patch detection scheme is much more effective than the widely used lexicographical sorting. © 2012 Elsevier Ireland Ltd.

Zhao H.,Tianjin University | Kunnath S.K.,University of California at Davis | Yuan Y.,Tongji University
Engineering Structures | Year: 2010

A computationally efficient macromodeling scheme to simulate the nonlinear behavior of composite structural connections consisting of steel-concrete composite beams and concrete-filled steel tubular (CFST) columns is investigated. The model proposed for composite beams, validated using four full scale composite beam tests, incorporates partial interaction between the concrete slab and the steel beam. The model proposed for CFST columns adopts fiber-based stress-strain relations that enable the consideration of strength and ductility for confined concrete and local buckling of the steel tube. The flexibility of the composite-beam-to-CFST-column connection is modeled as a panel zone. The validity of the simplified approach is evaluated by comparison of both overall response and local actions with those obtained from test results. The proposed methodology is shown to be viable for nonlinear analysis of composite structures wherein the modeling strategies are amenable to available features in modern nonlinear structural analysis software. © 2010 Elsevier Ltd.

Dai J.S.,Tianjin University | Dai J.S.,Kings College London
Mechanism and Machine Theory | Year: 2015

This paper reviews the Euler-Rodrigues formula in the axis-angle representation of rotations, studies its variations and derivations in different mathematical forms as vectors, quaternions and Lie groups and investigates their intrinsic connections. The Euler-Rodrigues formula in the Taylor series expansion is presented and its use as an exponential map of Lie algebras is discussed particularly with a non-normalized vector. The connection between Euler-Rodrigues parameters and the Euler-Rodrigues formula is then demonstrated through quaternion conjugation and the equivalence between quaternion conjugation and an adjoint action of the Lie group is subsequently presented. The paper provides a rich reference for the Euler-Rodrigues formula, the variations and their connections and for their use in rigid body kinematics, dynamics and computer graphics. © 2015 The Author. Published by Elsevier Ltd. This is an open access article under the CC BY license.

Cui L.,Kings College London | Dai J.S.,Kings College London | Dai J.S.,Tianjin University
Journal of Mechanisms and Robotics | Year: 2011

This paper investigates the 6R overconstrained mechanisms by looking at an arrangement that axes intersect at two centers with arbitrary intersection-angles. From the close-loop matrix equation of the mechanism, the paper develops a set of geometric constraint equations of the 6R double-centered overconstrained mechanisms. This leads to the axis constraint equation after applying the Sylvester's dialytic elimination method. The equation reveals the geometric constraint of link and axis parameters and identifies three categories of the 6R double-centered overconstrained mechanisms with arbitrary axis intersection-angles. The first two categories present two 6R double-centered overconstrained mechanisms and a 6R spherical mechanism. The last category evolves into the 6R double-spherical overconstrained mechanism with arbitrary axis intersection-angles at each spherical center. This further evolves into Baker's double-Hooke mechanism and his derivative double-spherical mechanism with orthogonal axis intersection. The paper further develops the joint-space solution of the 6R double-centered overconstrained mechanisms based on the geometric constraint equation and verifies the result with a numerical example. © 2011 American Society of Mechanical Engineers.

Cui L.,Kings College London | Dai J.S.,Tianjin University | Dai J.S.,Kings College London
Journal of Mechanisms and Robotics | Year: 2011

This paper presents a novel multifingered hand with an articulated palm that makes the hand adaptable and reconfigurable. The posture of the new multifingered hand is enhanced by the additional motion of the palm and the workspace of fingers is augmented by the palm workspace. To analyze this integrated workspace, this paper introduces finger-operation planes to relate the finger motion to the palm motion and its configuration. Normals of these operation planes are used to construct a Gauss map. Adding an additional dimension, a four-dimensional ruled surface can be generated from this map to illustrate variation of posture. With the change of palm configurations, a posture manifold can be developed from the posture ruled surfaces. The workspace analysis is developed by introducing a palm workspace-triangle. This workspace-triangle evolves into a helical workspace-triangle tube when palm inputs vary and further develops into a four-dimensional presentation. This progresses into a set of workspaces of the multifingered hand by varying the palm configuration, leading to a larger workspace of the new multifingered hand as the union of the workspaces corresponding to individual palm configuration. This paper further investigates manipulability of the multifingered hand by modeling the contact point as a hypothetical spherical joint. Based on reciprocity relationship of screw systems, the finger Jacobian matrices and the hand Jacobian matrix are established. With singular value decomposition, manipulability of each finger is explored and the hand manipulability is revealed by the diagonal nature of the Jacobian matrix of the hand. © 2011 American Society of Mechanical Engineers.

Liu A.A.,Tianjin University
Electronics Letters | Year: 2011

Proposed is a structured discriminative random fields model for human action recognition. To represent the human action in a compact but distinct manner, the motion-constrained SIFT (MoSIFT) algorithm is utilised for salient region extraction and description and Bag of Words is sequentially adopted for feature formulation to convert the action sequence into a feature sequence. With this feature representation, a structured discriminative random fields model can be constructed for action modelling and classification. The contribution of the work is to explicitly learn the visual pattern transition between elementary actions to discover the nature of the entire action rather than modelling the gradual change of visual pattern between adjacent frames in traditional methods. A large-scale experiment showed the accuracy and robustness of this method. Moreover, the proposed method outperforms the representative state-of-the-art methods for human action recognition. © 2011 The Institution of Engineering and Technology.

Yan S.W.,Tianjin University | Chu J.,Nanyang Technological University
Geotextiles and Geomembranes | Year: 2010

A study on the use of clay slurry filled geotextile mats to construct dikes for land reclamation at Tianjin Port, China, is presented in this paper. The dike so formed was covered by a thin layer of grouted geotextile mattress for protection. Through laboratory tests, a type of low plasticity clay was chosen to be the fill for the mats. A simple method for estimating the required tensile strength for the geotextile mat and the height of the mat was proposed. A preliminary design for the dike was made. Numerical analysis and centrifuge model tests were conducted to verify the design and assess the stability of the dike before construction. A field trial was also carried out in which a 100. m long and 4.8 m high dike was constructed on soft seabed. The dike has been stable and the settlement has been within the expected limit since the construction was completed in September 2001. © 2009 Elsevier Ltd.

Zhao J.J.,Tianjin University
Electronic Journal of Combinatorics | Year: 2015

Based on the combinatorial proof of Schur’s partition theorem given by Bressoud, and the combinatorial proof of Alladi’s partition theorem given by Padmavathamma, Raghavendra and Chandrashekara, we obtain a bijective proof of a partition theorem of Alladi, Andrews and Gordon. © 2015, Australian National University. All rights reserved.

Ma C.,Tianjin University
Xitong Gongcheng Lilun yu Shijian/System Engineering Theory and Practice | Year: 2013

Fast optimal decision of short-term dispatch of Three Gorges and Gezhouba cascade hydropower stations was developed with navigation and short-term electricity generation considered. Evaluation method of navigation condition and strategy of fast optimal decision of short-term dispatch were put forward with navigation guaranty rate, reservoir level guaranty rate and average reservoir level as decision indexes. Results show that multi feasible or best dispatch solutions of Three Gorges and Gezhouba cascade hydropower stations can be rapidly proposed by fast optimal decision strategy when schedule of Three Gorges hydropower station has been planned. And the best one not only satisfies navigation demand, but also increases daily electricity generation.

Li Y.,Tianjin University | Lu Z.,Zhejiang University | Zhu C.,Nanyang Technological University | Niu X.,Harbin Institute of Technology
IEEE Transactions on Image Processing | Year: 2012

In this paper, we propose a robust-hash function based on random Gabor filtering and dithered lattice vector quantization (LVQ). In order to enhance the robustness against rotation manipulations, the conventional Gabor filter is adapted to be rotation invariant, and the rotation-invariant filter is randomized to facilitate secure feature extraction. Particularly, a novel dithered-LVQ-based quantization scheme is proposed for robust hashing. The dithered-LVQ-based quantization scheme is well suited for robust hashing with several desirable features, including better tradeoff between robustness and discrimination, higher randomness, and secrecy, which are validated by analytical and experimental results. The performance of the proposed hashing algorithm is evaluated over a test image database under various content-preserving manipulations. The proposed hashing algorithm shows superior robustness and discrimination performance compared with other state-of-the-art algorithms, particularly in the robustness against rotations (of large degrees). © 2011 IEEE.

Liu Y.,University of Auckland | Zhao N.,Tianjin University | Gao W.,University of Auckland
RSC Advances | Year: 2013

The hierarchical ZnO nanostructures, branched nanorods, were prepared through a multi-step growth method on glass substrates without any capping agents. The process includes magnetron sputtering deposition of ZnO seed particles and hydrothermal growth of ZnO nanorods. The morphology, growth process and microstructure were characterized using scanning electron microscopy (SEM), high resolution transmission electron microscopy (HRTEM) and X-ray diffraction (XRD). The hierarchical structure consists of large primal nanorods as the trunks and much smaller secondary nanorods as the branches. Both the trunks and branches are single crystal grown along the [0001] direction. The ZnO seed particles which experienced Ostwald-ripening are essential for the growth of branched nanostructures. Raman scattering, photoluminescence (PL) emission and UV-Vis absorption were applied to measure the defects and optical properties. The hierarchical ZnO nanostructures exhibited the enhanced photocatalytic performance in degradation of Rhodamine B (RhB) under UV light, which can be attribute to the increased surface area, improved light harvesting, active surfaces, dense branch network and large amount of defects. This journal is © The Royal Society of Chemistry 2013.

Yin Y.H.,Tianjin University | Ikuta A.,Kinki University | North T.H.,University of Toronto
Materials and Design | Year: 2010

The microstructural features and mechanical properties of AM60 and AZ31 friction stir spot welds are investigated in joints made using different tool designs (threaded and three-flat/threaded tools) and dwell time settings. Since the hook regions are curved inwards towards the keyhole periphery in AM60 friction stir spot welds made using threaded and three-flat/threaded tools and different dwell time settings, the distance from the tip of the hook region to the keyhole periphery mainly determines their failure load properties. In contrast, the hook regions are curved outwards from the axis of the rotating tool in AZ31 friction stir spot welds and their failure strength properties are determined by the bonded width, the distance from the tip of the hook region to the sheet intersection, the depth of tool shoulder penetration into the surface of the upper sheet and the distance from the tip of the hook region to the top of the welded joint.The highest failure load properties are found in AM60 friction stir spot welds made using a three-flat/threaded tool and dwell times of 3 and 4. s, since the distance from the tip of the hook region to the keyhole periphery is highest in these joints. The highest failure load properties are found in AZ31 friction stir spot welds made using the three-flat/threaded tool and a dwell time of 1. s, since these joints have the largest bonded widths, distances from the tips of the hook regions to the sheet intersection, and limited penetration of the tool shoulder into the surface of the upper sheet (about 0.5 mm). © 2010 Elsevier Ltd.

The invention discloses a radio frequency front-end based on the high-intermediate frequency superheterodyne and zero intermediate frequency structure, which includes a transmitting module and a receiving module, wherein, the receiving module includes the following devices connected in turn with each other: a transceiving antenna, a low-pass filter, a superheterodyne unit, an IF band-pass filter, a zero-IF unit, a analog-to-digital converter and a digital baseband module of which the output is communicated with the transmitting module. The zero-IF unit includes the following devices which are also connected in turn with each other: a zero-IF mixer, an active low-pass filter and a variable gain operational amplifier of which the output is communicated with the input of the ADC; the inputs of the zero-IF mixer are communicated with the output of the IF band-pass filter and the second LO respectively. The present invention avoids the image interference, improves the system integration and decreases the system consumption.

Tianjin University and Gm Global Technology Operations Llc | Date: 2012-05-25

A non-stoichiometric perovskite oxide having the general chemical formula La

Du J.-L.,Tianjin University
Journal of Statistical Mechanics: Theory and Experiment | Year: 2012

We show that the general two-variable Langevin equations with inhomogeneous noise and friction can generate many different forms of power-law distributions. By solving the corresponding stationary Fokker-Planck equation, we can obtain a condition under which these power-law distributions are accurately created in a system away from equilibrium. This condition is an energy-dependent relation between the diffusion coefficient and the friction coefficient and thus it provides a fluctuation-dissipation relation for nonequilibrium systems with power-law distributions. Further, we study the specific forms of the Fokker-Planck equation that correctly lead to such power-law distributions, and then present a possible generalization of the Klein-Kramers equation and the Smoluchowski equation to a complex system, whose stationary-state solutions are exactly a Tsallis distribution. © 2012 IOP Publishing Ltd.

Tianjin University | Date: 2014-04-04

The present invention belongs to the field of utilization of distributed power generations and smart power management and, relates to an electric power router with multiple power supply modes; it includes a control unit, a communication module, a bidirectional alternate/direct current converter, a switch array, a direct current power line, two alternate current power lines, a power line measuring module, and router ports; wherein, the router ports include a plurality of power source ports and load ports; the switch array includes a single throw switch for grid connection and a plurality of double throw switches, all of which are controlled by the control unit; the direct current power source ports of the router ports are connected to the direct current power line, the direct current power line is connected to the second alternate current power line through the bidirectional alternate/direct current converter; the alternate current power source ports and load ports are connected through two alternate current power lines and the switch array. The present invention enables highly effective and smart management to kinds of power sources and loads, according to the power supplying condition of the power sources as well as the power consumption characteristics and consumption demands of the loads.

A harmonic-characteristics based current pattern matching method for the non-intrusive power load monitoring and disaggregation is provided in this present invention, on the basis of establishing the load signature database, which comprises electrical appliance registration and load state word space initialization, data acquisition and data preprocessing, feasible state word space search based on table looking-up, the optimal matching of current pattern, and display and output of the monitoring and disaggregation results. The method improves the accuracy of disaggregation, and can achieves exact identification of operating states of appliances, and also can reduce the cost.

Tianjin University | Date: 2012-11-06

The present invention discloses a method for producing vinyl acetate. Inert gas is introduced into cycling gas to improve the explosion limit of oxygen, enlarge a stable area of a reaction system and improve the oxygen concentration of the reaction system, thus reducing the reaction temperature, prolonging the service life of a catalyst, and improving the selectivity of the vinyl acetate. The inert gas is nitrogen or a mixture of nitrogen and methane. The concentration of the inert gas at the inlet of a reactor is 8 to 30 mol %. The molar concentration of the oxygen at the inlet of the reactor is 10.5 to 12 mol %.

A preparation method of an enhanced-type polyacrylonitrile hollow fiber membrane comprises steps of: (1) knitting a polyacrylonitrile fiber hollow braided tube by a two-dimensional weaving technology; wherein the polyacrylonitrile fiber hollow braided tube is utilized as a reinforcement of a hollow fiber membrane; (2) preparing polyacrylonitrile casting solution, wherein, polyacrylonitrile resin is 3%-25%; solvent is 50%-95%; and additive is 2%-30%; a sum of the mass percent of all composition mentioned above is 100%; (3) infiltrating the polyacrylonitrile fiber hollow braided tube by weak polar organic liquid, wherein, a time of the polyacrylonitrile fiber hollow braided tube infiltrated is is-60

and Technology Inc., Tianjin University and Tokyo Electric Power Company | Date: 2012-10-11

A system for accurately determining real-time Available Transfer Capability and the required ancillary service of large-scale interconnected power systems in an open-access transmission environment, subject to static and dynamic security constraints of a list of credible contingencies, including line thermal limits, bus voltage limits, voltage stability (steady-state stability) constraints, and transient stability constraints.

Li J.,Hebei United University | Zheng Z.,Tianjin University
Advances in Information Sciences and Service Sciences | Year: 2012

The problem of evaluating the technical innovation capacity of high-tech industry with uncertain linguistic information is the multiple attribute decision making (MADM) problems. In this paper, we investigate the multiple attribute decision making (MADM) problems for evaluating the technical innovation capacity of high-tech industry with uncertain linguistic information. We utilize the uncertain extended weighted geometric averaging (UEWGA) operator to aggregate the uncertain linguistic information corresponding to each alternative and get the overall value of the alternatives, then rank the alternatives and select the most desirable one(s) by using the formula of the degree of possibility for the comparison between two uncertain linguistic variables. Finally, an illustrative example for technical innovation capacity of high-tech industry with uncertain linguistic information is given.

During the neohepatic stage of liver transplantation, hemodynamics change markedly. The present study aimed to investigate whether gastrointestinal congestion due to inferior vena cava and hepatic portal vein clamping can dilate the hepatic artery and to determine the associated mechanisms. Ring segments of the hepatic artery was treated with the plasma from gastrointestinal congestion or the superior vena cava. The fractions in gastrointestinal congestion and the superior vena cava plasma were tested, and the effect of these fractions on the tone of the hepatic artery ring was examined. Different signal transduction blockers and different inhibitors were then used to determine the exact signal transduction pathway involved. Additionally, endothelial cell structure was observed by transmission electron microscopy after treatment with the gastrointestinal congestion plasma or the superior vena cava plasma. Gastrointestinal congestion plasma contained more inflammatory cytokines than superior vena cava plasma, and these cytokines could cause hepatic artery ring dilatation. A P38 mitogen-activated protein kinase (P38 MAPK) signal transduction pathway blocker and nitric oxide (NO), prostacyclin (PGI2), nuclear factor-κB (NF-κB), and adenosine triphosphate (ATP)-sensitive K (KATP ) channel inhibitors were able to significantly reverse the ring tension caused by gastrointestinal congestion plasma. The normal endothelium was also injured by treatment with gastrointestinal congestion plasma. The inflammatory cytokines in gastrointestinal congestion can cause hepatic artery ring dilatation through the P38 MAPK signal transduction pathway, and this phenomenon is also associated with NO, PGI2, NF-κB, and the KATP Channel. These inflammatory cytokines can injure endothelial cells in the hepatic artery. Copyright © 2016 by the American Society for Artificial Internal Organs

Yong Y.-C.,Jiangsu University | Yu Y.-Y.,Nanyang Technological University | Zhang X.,South University of Science and Technology of China | Song H.,Nanyang Technological University | Song H.,Tianjin University
Angewandte Chemie - International Edition | Year: 2014

Low extracellular electron transfer performance is often a bottleneck in developing high-performance bioelectrochemical systems. Herein, we show that the self-assembly of graphene oxide and Shewanella oneidensis MR-1 formed an electroactive, reduced-graphene-oxide-hybridized, three-dimensional macroporous biofilm, which enabled highly efficient bidirectional electron transfers between Shewanella and electrodes owing to high biomass incorporation and enhanced direct contact-based extracellular electron transfer. This 3D electroactive biofilm delivered a 25-fold increase in the outward current (oxidation current, electron flux from bacteria to electrodes) and 74-fold increase in the inward current (reduction current, electron flux from electrodes to bacteria) over that of the naturally occurring biofilms. Shocking bacteria! The title biofilm was constructed by the one-step in?situ bioreduction and self-assembly of graphene oxide (GO) with Shewanella oneidensis. The resulting 3D macroporous rGO/bacteria hybrid biofilm gave a 25-fold increase in maximum oxidation current in microbial fuel cells, and a 74-fold increase in reduction current in microbial electrosynthesis over that of the naturally occurring biofilms. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Ren X.B.,Tianjin University of Science and Technology | Ren K.,Tianjin University
Solid State Communications | Year: 2011

The influence of disorders in the fabrication process on the focusing performance of two-dimensional optical quasicrystal slab is investigated. Two types of disorders are considered: positional randomness and radius randomness. The change in field distribution for E polarization and H polarization is examined by using the finite-difference time-domain method. We find that for both polarizations disorder has a detrimental effect on the focusing performance of quasicrystal lens. The tolerance of the focusing function to structural disorders is examined in detail. We show that the focusing quality is much more sensitive to the fluctuation of radius than to the randomness of position. These results will be helpful in devising photonic imaging devices based on quasiperiod photonic crystals. © 2010 Elsevier Ltd. All rights reserved.

A simple, rapid, and sensitive method for visual detection of sequence-specific DNA was developed using hairpin DNA as the recognition element and hydroxylamine-enlarged gold nanoparticles (Au-NPs) as the signal producing component. In the assay, we employed a hairpin DNA probe dually labeled with amine and biotin at the 5'- and 3'-end, respectively. The probe was coupled with reactive N-oxysuccinnimide in a DNA-bind 96-well plate. Without the target DNA, the immobilized hairpin probe was in a "closed" state, which kept the streptavidin-gold off the biotin. The hybridization between the loop sequence and the target broke the short stem duplex upon approaching the target DNA. Consequently, biotin was forced away from the 96-well plate surface and available for conjugation with the streptavidin-gold. The hybridization could be detected visually after the HAuCl(4)-NH(2)OH redox reaction catalyzed by the Au-NPs. Under the optimized conditions, the visual DNA sensor could detect as low as 100 amol of DNA targets with excellent differentiation ability and even a single-base mismatch.

Yin S.,Tianjin University
Sensors (Basel, Switzerland) | Year: 2013

A vision-based robot self-calibration method is proposed in this paper to evaluate the kinematic parameter errors of a robot using a visual sensor mounted on its end-effector. This approach could be performed in the industrial field without external, expensive apparatus or an elaborate setup. A robot Tool Center Point (TCP) is defined in the structural model of a line-structured laser sensor, and aligned to a reference point fixed in the robot workspace. A mathematical model is established to formulate the misalignment errors with kinematic parameter errors and TCP position errors. Based on the fixed point constraints, the kinematic parameter errors and TCP position errors are identified with an iterative algorithm. Compared to the conventional methods, this proposed method eliminates the need for a robot-based-frame and hand-to-eye calibrations, shortens the error propagation chain, and makes the calibration process more accurate and convenient. A validation experiment is performed on an ABB IRB2400 robot. An optimal configuration on the number and distribution of fixed points in the robot workspace is obtained based on the experimental results. Comparative experiments reveal that there is a significant improvement of the measuring accuracy of the robotic visual inspection system.

The paper presents a joint subcarrier-pair based resource allocation algorithm in order to improve the efficiency and fairness of cooperative multiuser orthogonal frequency division multiplexing (MU-OFDM) cognitive radio (CR) systems. A communication model where one source node communicates with one destination node assisted by one half-duplex decode-and-forward (DF) relay is considered in the paper. An interference-limited environment is considered, with the constraint of transmitted sum-power over all channels and aggregate average interference towards multiple primary users (PUs). The proposed resource allocation algorithm is capable of maximizing both the system transmission efficiency and fairness among secondary users (SUs). Besides, the proposed algorithm can also keep the interference introduced to the PU bands below a threshold. A proportional fairness constraint is used to assure that each SU can achieve a required data rate, with quality of service guarantees. Moreover, we extend the analysis to the scenario where each cooperative SU has no channel state information (CSI) about non-adjacent links. We analyzed the throughput and fairness tradeoff in CR system. A detailed analysis of the performance of the proposed algorithm is presented with the simulation results.

Sun D.-Z.,Tianjin University | Zhong J.-D.,Tongji University
IEEE Transactions on Consumer Electronics | Year: 2012

RFID (Radio Frequency Identification) tags are small, wireless electronic devices that help identify objects and people. Privacy protection and integrity assurance become rather crucial in the RFID systems, because these RFID tags may have a wide transmission range, making them subject to unauthorized scanning by malicious readers and various other attacks. Hence, Ha et al. proposed an RFID protocol and proved that their protocol can provide the forward privacy service. However, in this paper, it is shown that an attacker can track a target tag by observing unsuccessful previous session of the tag. That is, Ha et al.'s RFID protocol fails to provide the forward privacy protection as claimed. Therefore, to overcome the privacy weaknesses of Ha et al.'s RFID protocol, an RFID protocol based on the cryptographic hash functions is proposed. Moreover, the proposed RFID protocol is evaluated according to both the privacy attribute and the implementation performance. © 2011 IEEE.

Wu S.,Hubei University | Liu X.,Hubei University | Yeung K.W.K.,University of Hong Kong | Liu C.,East China University of Science and Technology | And 2 more authors.
Materials Science and Engineering R: Reports | Year: 2014

Increased use of reconstruction procedures in orthopedics, due to trauma, tumor, deformity, degeneration and an aging population, has caused a blossom, not only in surgical advancement, but also in the development of bone implants. Traditional synthetic porous scaffolds are made of metals, polymers, ceramics or even composite biomaterials, in which the design does not consider the native structure and properties of cells and natural tissues. Thus, these synthetic scaffolds often poorly integrate with the cells and surrounding host tissue, thereby resulting in unsatisfactory surgical outcomes due to poor corrosion and wear, mechanical mismatch, unamiable surface environment, and other unfavorable properties. Musculoskeletal tissue reconstruction is the ultimate objective in orthopedic surgery. This objective can be achieved by (i) prosthesis or fixation device implantation, and (ii) tissue engineered bone scaffolds. These devices focus on the design of implants, regardless of the choice of new biomaterials. Indeed, metallic materials, e.g. 316L stainless steel, titanium alloys and cobalt chromium alloys, are predominantly used in bone surgeries, especially in the load-bearing zone of prostheses. The engineered scaffolds take biodegradability, cell biology, biomolecules and material mechanical properties into account, in which these features are ideally suited for bone tissue repair and regeneration. Therefore, the design of the scaffold is extremely important to the success of clinical outcomes in musculoskeletal surgeries. The ideal scaffolds should mimic the natural extracellular matrix (ECM) as much as possible, since the ECM found in natural tissues supports cell attachment, proliferation, and differentiation, indicating that scaffolds should consist of appropriate biochemistry and nano/micro-scale surface topographies, in order to formulate favorable binding sites to actively regulate and control cell and tissue behavior, while interacting with host cells. In addition, scaffolds should also possess a similar macro structure to what is found in natural bone. This feature may provide space for the growth of cells and new tissues, as well as for the carriers of growth factors. Another important concern is the mechanical properties of scaffolds. It has been reported that the mechanical features can significantly influence the osteointegration between implants and surrounding tissues, as well as cell behaviors. Since natural bone exhibits super-elastic biomechanical properties with a Young's modulus value in the range of 1-27 GPa, the ideal scaffolds should mimic strength, stiffness and mechanical behavior, so as to avoid possible post-operation stress shielding effects, which induce bone resorption and consequent implant failure. In addition, the rate of degradation and the by-products of biodegradable materials are also critical in the role of bone regeneration. Indeed, the mechanical integrity of a scaffold will be significantly reduced if the degradation rate is rapid, thereby resulting in a pre-matured collapse of the scaffold before the tissue is regenerated. Another concern is that the by-products upon degradation may alter the tissue microenvironment and then challenge the biocompatibility of the scaffold and the subsequent tissue repair. Therefore, these two factors should be carefully considered when designing new biomaterials for tissue regeneration. To address the aforementioned questions, an overview of the design of ideal biomimetic porous scaffolds is presented in this paper. Hence, a number of original engineering processes and techniques, including the production of a hierarchical structure on both the macro- and nano-scales, the adjustment of biomechanical properties through structural alignment and chemical components, the control of the biodegradability of the scaffold and its by-products, the change of biomimetic surface properties by altering interfacial chemistry, and micro- and nano-topographies will be discussed. In general, the concepts and techniques mentioned above provide insights into designing superior biomimetic scaffolds for bone tissue engineering. © 2014 Elsevier B.V.

Liang J.,University of Adelaide | Zhou R.F.,University of Adelaide | Chen X.M.,Tianjin University | Tang Y.H.,Flinders University | Qiao S.Z.,University of Adelaide
Advanced Materials | Year: 2014

An Fe-N-decorated hybrid material of carbon nanotubes (CNTs) grown in situ from porous carbon microblocks is designed and constructed. This material successfully combines the desirable merits for oxygen reduction reaction (ORR), such as highly active Fe-N species, good conductivity, large pore size, and sufficient surface area. These structural advantages give this low-priced material an outstanding catalytic performance for ORR closely comparable with Pt/C of the same quantity. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Foam is used as an efficient means of firefighting. The innovative foaming device using gas as the sole power is designed to replace the previous foam generating system using two or three power sources, and appropriate size of the new foaming device can be made to control dust and fire in households or companies based on the actual need. The results of the experimental investigation on the new device in three cases are as follows: in the first case, the minimum working pressure is 0.4 MPa and the working flow range is: 8.0858 m3/h≤qa ≤ 48.45 m3/h and qL ≤ 0.4532 m3/h. In the second case, the maximum working time of the new foaming device is 109 s and the minimum working pressure of the storage tank II is 0.26 Mpa. In the third case, the maximum working time of the new device is 205 s and the minimum working pressure values of the storage tanks I and II are 0.26 Mpa and 0.3 Mpa respectively. The fire extinguishing experiment is explained in this article, and the results show that the foam generated by the new foaming device is more effective and efficient than the ABC powder fire extinguisher. © 2016 American Institute of Chemical Engineers.

Mu Y.,University of Cardiff | Wu J.,University of Cardiff | Ekanayake J.,University of Cardiff | Jenkins N.,University of Cardiff | Jia H.,Tianjin University
IEEE Transactions on Smart Grid | Year: 2013

With the increasing use of renewable energy in the Great Britain (GB) power system, the role of electric vehicles (EVs) contributes to primary frequency response was investigated. A tool was developed to estimate the EV charging load based on statistical analysis of EV type, battery capacity, maximum travel range and battery state of charge. A simplified GB power system model was used to investigate the contribution of EVs to primary frequency response. Two control modes were considered: disconnection of charging load (case I) and discharge of stored battery energy (case II). For case II, the characteristic of the EV charger was also considered. A case study shows results for the year 2020. Three EV charging strategies: 'dumb' charging, 'off-peak' charging, and 'smart' charging, were compared. Simulation results show that utilizing EVs to stabilize the grid frequency in the GB system can significantly reduce frequency deviations. However the requirement to schedule frequency response from conventional generators is dynamic throughout the day. © 2010-2012 IEEE.

Mi L.-Z.,Harvard University | Mi L.-Z.,Tianjin University | Brown C.T.,Pfizer | Gao Y.,Pfizer | And 5 more authors.
Proceedings of the National Academy of Sciences of the United States of America | Year: 2015

Bone morphogenetic proteins (BMPs) belong to the TGF-β family, whose 33 members regulate multiple aspects of morphogenesis. TGF-β family members are secreted as procomplexes containing a small growth factor dimer associated with two larger prodomains. As isolated procomplexes, some members are latent, whereas most are active; what determines these differences is unknown. Here, studies on pro-BMP structures and binding to receptors lead to insights into mechanisms that regulate latency in the TGF-β family and into the functions of their highly divergent prodomains. The observed open-armed, nonlatent conformation of pro-BMP9 and pro-BMP7 contrasts with the cross-armed, latent conformation of pro-TGF-β1. Despite markedly different arm orientations in pro-BMP and pro-TGF-β, the arm domain of the prodomain can similarly associate with the growth factor, whereas prodomain elements N- and C-terminal to the arm associate differently with the growth factor and may compete with one another to regulate latency and stepwise displacement by type I and II receptors. Sequence conservation suggests that pro-BMP9 can adopt both cross-armed and open-armed conformations.We propose that interactors in the matrix stabilize a cross-armed pro-BMP conformation and regulate transition between cross-armed, latent and open-armed, nonlatent pro-BMP conformations.

Zhang L.,Tianjin University
Scientometrics | Year: 2014

This study examines China's performance on tissue engineering using scientometrics measures such as China's global publication share, rank, growth rate and citation impact, its publications in various sub-fields, top journals in terms of national share based on last 5 years (2008-2012) publications data obtained from ISI Science citation index expanded database. We have also determined Chinese share with international collaborative papers at the national level, as well as h-core papers and high-cited papers, etc. © 2013 Akadémiai Kiadó, Budapest, Hungary.

Peng X.-L.,University of Western Australia | Hao H.,University of Western Australia | Li Z.-X.,Tianjin University
Engineering Structures | Year: 2012

Subsea pipelines provide a vital transportation service to transport natural oil or gas from offshore wells to an onshore location. Free-spanning damage is one of very common problems both in the design phase and during operation of pipelines. The objective of this paper is to identify free span locations and severities using a vibration-based method. Most vibration-based damage detection methods require the modal properties obtained from measured signals through the system identification techniques. However, for a long subsea pipeline without clear boundary, it may not be able to obtain its modal properties reliably. In this study, a signal-based damage detection method using wavelet packet energy is applied to assess pipeline bedding conditions. A damage index called average wavelet packet energy change rate (. WPECR) based on the covariance of output signals excited by ambient wave force is proposed to identify free-spanning damage. Numerical simulation is firstly used to verify the feasibility of this method. Then ambient vibration tests are carried out on a scaled pipe model to further verify the applicability of this method. Both simulated and experimental studies demonstrate that the WPECR is a good index for assessing pipeline bedding conditions. © 2012 Elsevier Ltd.