Dalian, China

Dalian University of Technology , colloquially known in Chinese as Dagong , is a public research university located in Dalian and Panjin, Liaoning province, People's Republic of China. DUT, previously renowned as one of the Big Four Institutes of Technology, is among China's top universities for engineering and technology. It is also one of the national key universities administered directly under the Ministry of Education of China. Wikipedia.

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Dalian University of Technology | Date: 2014-11-26

The present invention provides a difluoroboron dipyrromethene fluorescent probe having a structure represented by the following general formula I, and a production method and an application thereof. Said difluoroboron dipyrromethene fluorescent probe exhibits low background fluorescence, and a rapid and significant fluorescence enhancement up to 100 times after the addition of hypochloric acid. The fluorescent intensity of said fluorescent probe shows a good linear relation with the concentration of hypochloric acid in a nanomole level, and the detection limit thereof is 0.56 nanomole. Said fluorescent probe has good selectivity since it hardly responds to other reactive oxygen species such as H_(2)O_(2), O_(2)^(), TBHP, HO., TBO., ^(1)O_(2 )and NO., and is not interfered by pH in a wide range. Said fluorescent probe can be applied to detect hypochloric acid in living cells.

Dalian University of Technology | Date: 2016-08-03

A wave power generation device, including a power generation assembly, a mooring system, a floating platform, floating towers, control cabins, a connecting member, and anti-sway plates. The floating platform is a square floating box. The power generation assembly includes a swing plate, a hydraulic cylinder, an energy accumulator, a hydraulic motor, a generator, a battery, and a power generation and distribution device. The floating platform includes a main deck. The main deck includes a manhole and a support for supporting the swing plate. The swing plate is connected to the support via a first hinge. One end of the hydraulic cylinder is connected to the swing plate, and another end of the hydraulic cylinder is connected to a floating platform. The mooring system includes four anchor windlasses. A method for operating and maintaining the wave power generation device is also provided.

Li W.,Dalian University of Technology | Li C.,Dalian University of Technology | Song H.,Dalian University of Technology
Physical Review E - Statistical, Nonlinear, and Soft Matter Physics | Year: 2017

We investigate the quantum synchronization phenomenon of the complex network constituted by coupled optomechanical systems and prove that the unknown identical quantum states can be shared or distributed in the quantum network even though the topology is varying. Considering a channel constructed by quantum correlation, we show that quantum synchronization can sustain and maintain high levels in Markovian dissipation for a long time. We also analyze the state-sharing process between two typical complex networks, and the results predict that linked nodes can be directly synchronized, but the whole network will be synchronized only if some specific synchronization conditions are satisfied. Furthermore, we give the synchronization conditions analytically through analyzing network dynamics. This proposal paves the way for studying multi-interaction synchronization and achieving effective quantum information processing in a complex network. © 2017 American Physical Society.

Jiang Y.,UNESCO-IHE Institute for Water Education | Jiang Y.,Dalian University of Technology | Swallow S.K.,University of Connecticut
Ecological Economics | Year: 2017

Communities in exurban areas increasingly rely on land preservation as a strategy to balance sprawling land development with maintaining environmental amenities. Based on a review of existing approaches for preserving land, we consider a conceptual model of environmental impact fees (EIFs) coupled with conservation payments for managing private land of ecosystem value. In this framework, conservation payments are intended to cost-effectively target fair market value compensation for heterogeneous land for preservation that sustains ecosystem health. EIFs serve as a financial instrument to augment conservation payments and to allow flexibility for landowners with private information to pursue development opportunities while accounting for environmental impacts. Using a bioeconomic model of nature-reserve design, we develop an empirical illustration of how to estimate the EIF of development damage to critical habitat in southern Rhode Island in an effort to preserve land as an environmental infrastructure that maintains ecosystem health. © 2017 The Authors

Zhong S.,Dalian University of Technology | Bushell M.,Orange County
Journal of Transport Geography | Year: 2017

This paper analyzes the impacts of the built environment (BE) as it relates to the potential job accessibility (PJA) effects of road pricing. The relationships between the BE elements and PJA under a road charging policy are established using a spatial econometric approach, which uses an integrated land use and transportation model (TRANUS model) and a spatial lag model (SLM). With the intent of further analyzing the differences in the PJA effects of road pricing on traffic analysis zones (TAZs) that contain different combinations of BE elements, a quantitative classification method combining factor and cluster analysis is applied. This will quantitatively categorize TAZs inside and outside the tolled areas. In exploring the relationship between changes in PJA and the road pricing policy, we found the spatial autocorrelation coefficient to be negative. This result suggests that we are unable to increase the PJA of all the regions through road pricing, but rather affect a redistribution of PJA between different regions. Results also indicate that the impacts of road charging on PJA are associated with urban BE elements. Moreover, such effects are the common result of specific characteristics of the BE. The higher the number of jobs, the better the public transportation conditions, and the better the street design (high densities of street and intersections), the less the region will be negatively influenced by a road charging policy, and vice versa. To avoid the negative effects of road pricing on PJA prior to the launch of such a policy, cities should improve public transportation networks and enhance the street design of the road pricing policy areas, especially the toll ring periphery area. © 2017 Elsevier Ltd

Feng X.,Dalian University of Technology
Nature Environment and Pollution Technology | Year: 2017

Air quality has the strong regional characteristics, and the land use type can reflect human activities in the area to some extent. In order to explore the spatial relationships between air quality indicators (PM2.5, PM10, O3, SO2, NO2, CO) and land use indicators ( tree, grass, farm, water and building proportion), the ordinary least squares (OLS) and geographically weighted regression (GWR) models are established and tested by comparing R2 and AICc (Akaika Information Criterion corrected) of the models. The Moran's I statistics on the residuals from OLS and GWR models shows that the GWR models can be a good deal with the spatial autocorrelation. Meanwhile local parameters at different locations from GWR models can be good performance in the spatial heterogeneity of the air quality and land use, providing a scientific basis for rational and effective regional governance.

Liu H.H.,Dalian University of Technology | Jiang W.,Dalian University of Technology
IOP Conference Series: Earth and Environmental Science | Year: 2017

Stator can assembly is one of difficult issues in the manufacturing of AP1000 nuclear reactor coolant pumps. A new measurement and control system is developed to ensure precise assembly of the ultrathin stator can with large length to thickness ratio on the stator core. The system includes three parts: hydraulic pressure measurement and control, deformation measurement of the can and displacement measurement of valve core. Since deformation of the can is hard to measure, a new method by measuring the bulge displacement of the can is proposed. With the help of the system, the loading path can be accurately controlled and the deformation can be precisely measured. The system provides possibility for the detailed study of assembly process. Finally, the feasibility of the system in the experiment rig of a reduced scale is verified. © Published under licence by IOP Publishing Ltd.

Zhao Z.,Dalian University of Technology | Guo Y.,Dalian University of Technology
Catalysis Communications | Year: 2017

The well-dispersed supported sulphated La2O3-ZrO2 (SLZ) superacid catalysts on SBA-15 with loadings were prepared and applied in alkenylation of p-xylene with phenylacetylene. The amount of acidic sites increases with the enlarged loading, it reaches maximum at the loading of 25%, and then decreases while the loading is further increased. The increasing loading leads to a continuous decrease in specific surface area and pore volume. The optimized 25% SLZ/SBA-15 catalyst shows the outstanding catalytic performance, attributed to the more acidic sites and the not too low surface area and pore volume. The developed well-ordered mesoporous sulphated La2O3-ZrO2 solid superacid catalyst may be extended to diverse transformations. © 2017 Elsevier B.V.

Bao J.,Dalian University of Technology | Wang L.,Dalian University of Technology
Journal of Materials in Civil Engineering | Year: 2017

The synergetic effects of the environmental and loading actions on mass transport process in concrete play an important role for the deterioration of mechanical properties and durability problems of reinforced concrete (RC) structures. Water is either the main agent responsible for the deterioration of concrete or the principal transport medium carrying aggressive species to ingress into concrete. This paper presents the results of an experimental investigation on the effect of short-term sustained uniaxial compressive or tensile loadings on water absorption by hollow cylindrical concrete specimens. An improved test apparatus aimed for the coupled effect of sustained loading on water absorption was designed to measure in real time the amount of water absorbed by the concrete specimen. The cumulative water content and axial/lateral strain of specimens under various stress levels (approximately 0-50%) were recorded. It was noted that under the short-term sustained tensile loading, the cumulative water content at a given exposed time generally increases with an increase of the stress level, while for the compressive case it initially decreases and then increases. The initial and secondary sorptivities, which are defined for characterizing the tendency of concrete to absorb water by the capillarity versus the compressive stress level, conformed to the polynomial function, except for the tensile loading case. which exhibited a linear relation. The ratio between initial and secondary sorptivity, as well as the quantitative correlations between the two sorptivities and stress level were proposed to account for the sustained loading effect on water absorption of concrete. Based on the unsaturated flow theory (UFT) model and experimental data, two forms of diffusivity, i.e., the exponential law and power functions, were both adopted to predict water distribution within a concrete sample under compressive/tensile stress states after 32-h absorption. The results indicated that the predicted water penetration depths by means of both exponential law and power functions in the UFT model increases with the increase of sustained compressive/tensile stress levels. The validation of the proposed model shows good correlation between the predicted water zpenetration depth and the test data. © 2016 American Society of Civil Engineers.

Song Z.,Dalian Polytechnic University | Sun K.,Dalian University of Technology
Asian Journal of Control | Year: 2017

This paper investigates the attitude control problem of a quad-rotor unmanned helicopter. In response to adverse factors, including the lumped disturbance, inertia parameter uncertainties, and the partial loss of rotation effectiveness, an adaptive compensation control strategy combining the terminal sliding mode technique and the input shaping method is proposed. Specifically, a group of updating laws using an adaptive mechanism is added to adjust the control strategy in a manner conductive to attitude stability and performance preservation in the presence of adverse factors. The key features of the proposed control strategy are that it is independent from the knowledge of actuator faults, and adaptive compensation control is achieved without the need for online identification of rotor failure. The finite time convergence and stability of the attitude tracking errors are proved by using Lyaponov's method. Finally, the simulation results demonstrate the effectiveness of the proposed control strategy. © 2017 Chinese Automatic Control Society and John Wiley & Sons Australia, Ltd.

Li P.,Dalian University of Technology | Wang Q.,Dalian University of Technology | Zeng H.,Dalian University of Technology | Zhang L.,Hong Kong Polytechnic University
IEEE Transactions on Pattern Analysis and Machine Intelligence | Year: 2017

This paper presents a novel image descriptor to effectively characterize the local, high-order image statistics. Our work is inspired by the Diffusion Tensor Imaging and the structure tensor method (or covariance descriptor), and motivated by popular distribution-based descriptors such as SIFT and HOG. Our idea is to associate one pixel with a multivariate Gaussian distribution estimated in the neighborhood. The challenge lies in that the space of Gaussians is not a linear space but a Riemannian manifold. We show, for the first time to our knowledge, that the space of Gaussians can be equipped with a Lie group structure by defining a multiplication operation on this manifold, and that it is isomorphic to a subgroup of the upper triangular matrix group. Furthermore, we propose methods to embed this matrix group in the linear space, which enables us to handle Gaussians with Euclidean operations rather than complicated Riemannian operations. The resulting descriptor, called Local Log-Euclidean Multivariate Gaussian (L2 EMG) descriptor, works well with low-dimensional and high-dimensional raw features. Moreover, our descriptor is a continuous function of features without quantization, which can model the first- and second-order statistics. Extensive experiments were conducted to evaluate thoroughly L2 EMG, and the results showed that L2 EMG is very competitive with state-of-the-art descriptors in image classification. © 1979-2012 IEEE.

Liu H.,Wuhan University | Lv J.,Dalian University of Technology
Composite Structures | Year: 2017

In this work, an equivalent continuum multiscale formulation is presented for the geometrical nonlinear analysis of the structures with lattice truss materials. This formulation is established by combining the extended multiscale finite element method and the co-rotational approach. Firstly, the lattice truss unit cell is equivalent to a continuum coarse element by using a numerical constructed interpolation function in the local coordinate system. Then the tangent stiffness matrix of this coarse element is derived by employing the basic idea of the co-rotational approach in the global coordinate system. Thus, the global nonlinear equilibrium equations of the structure at the macroscopic level can be solved by using the general displacement control algorithm to capture the equilibrium path with multiple critical points. After performing all of the incremental steps and the iterative steps on the macroscopic scale, the microscopic information, such as the displacement, stress and strain, can be obtained easily by virtue of the afore-constructed numerical interpolation functions once again. In addition, several numerical examples are carried out to study the effects of the layout and size of unit cell, investigate the sensitivity of coarse-scale meshes and verify the validation and efficiency of the presented multiscale formulation. © 2016 Elsevier Ltd

Liu Z.,Dalian University of Technology | Wang Y.,Dalian University of Technology
Journal of Engineering for Gas Turbines and Power | Year: 2017

Many rotor assemblies of industrial turbomachines are supported by oil-lubricated bearings. It is well known that the operation safety of these machines is highly dependent on rotors whose stability is closely related to the whirling motion of lubricant oil. In this paper, the problem of transverse motion of rotor systems considering bearing nonlinearity is revisited. A symmetric, rigid Jeffcott rotor is modeled considering unbalanced mass and short bearing forces. A semi-analytical, seminumerical approach is presented based on the generalized harmonic balance method (GHBM) and the Newton-Raphson iteration scheme. The external load of the system is decomposed into a Fourier series with multiple harmonic loads. The amplitude and phase with respect to each harmonic load are solved iteratively. The stability of the motion response is analyzed through identification of eigenvalues at the fixed point mapped from the linearized system using harmonic amplitudes. The solutions of the present approach are compared to those from time-domain numerical integrations using the Runge-Kutta method, and they are found to be in good agreement for stable periodic motions. It is revealed through bifurcation analysis that evolution of the motion in the nonlinear rotor-bearing system is complicated. The Hopf bifurcation (HB) of synchronous vibration initiates oil whirl with varying mass eccentricity. The onset of oil whip is identified when the saddle-node bifurcation of subsynchronous vibration takes place at the critical value of parameter. Copyright © 2017 by ASME.

Fang Y.,Dalian University of Technology | Chang J.,Dalian University of Technology
Journal of Thermal Analysis and Calorimetry | Year: 2017

This paper presents a study on rapid hardening behaviors of β-C2S by accelerated carbonation curing. β-C2S cubes compacted at various molding pressures were subjected to different CO2 concentration for accelerated carbonation curing. The CO2 uptake and microstructure changes were analyzed by thermogravimetric analysis (TG), QXRD, FT-IR and MAS-NMR. The results indicated that CO2 uptake was affected by molding pressure and CO2 concentration seriously. TG analysis indicated that the carbonation reaction was rapid in the first hour. The carbonation degree reached 21.6% and giving a compressive strength of 85.7 MPa after 6 h carbonation in 99.9% CO2 concentration. And it showed a much less carbonation degree in 20.0% CO2. Calcite, vaterite and amorphous silica-rich phase formed in the carbonation progress. The FT-IR and NMR analysis indicated β-C2S was decalcified to C–S–H gel and further decalcified to formation of an amorphous silica gel composed of Q3 and Q4 silicate tetrahedral. The chain length of C–S–H gel increased from to 2.67 to 6.36 with prolonged carbonation time, showing a lower C/S ratio and higher polymerization and also resulting in a lower C–S–H content. © 2017 Akadémiai Kiadó, Budapest, Hungary

Gong B.,Dalian University of Technology | Tang C.,Dalian University of Technology
International Journal of Geomechanics | Year: 2017

The discontinuous deformation and displacement (DDD) analysis method, a combination of the realistic failure-process analysis (RFPA) and discontinuous deformation analysis (DDA) methods, offers an appropriate approach for whole rock failure-process analysis involving both the small deformation and large displacement stages. A high rock-slope slide at the Alpetto Mine in Cesana Brianza, Italy, was simulated with the DDD method, and the results are consistent with site observations and previous numerical results, which validates the DDD code for this kind of geotechnical problem. Moreover, this study verified the two main advantages of the DDD method, i.e., the critical failure surface can be obtained directly without any assumptions with the RFPA module before using the DDA module, and computing efficiency is improved significantly because the large displacement elements are the only elements that need to be calculated by the DDA module. The DDD method has proved to be an effective and efficient approach for engineers in the field of rock slopes, and it shows huge potential in geotechnical engineering. © 2016 American Society of Civil Engineers.

Cheng G.,Dalian University of Technology | Cheng G.,University of Tasmania | Cheng G.,Shaanxi Coal and Chemical Technology Institute Co.
International Journal of Rock Mechanics and Mining Sciences | Year: 2017

A microseismic monitoring technique is adopted to investigate the distribution regularity of microseismic events released by the coal mining - induced roof rock mass along the vertical and horizontal directions in combination with mine geological data. On the basis of the quantity and energy distributions of the microseismic events recorded using the microseismic monitoring technique, a zoning method is first established for the roof strata movement in the vertical and horizontal directions. The vertically zoning method is then applied to analyze the microseismic monitoring results obtained in the Dongjiahe Coal Mine, which divides rock mass into six zones along the vertical direction, i.e. the caved zone, the block zone, the vertical fracture through-going zone, the vertical fracture zone, the separation zone and the continuous zone. The horizontally zoning model divides the roof strata movement into three zones, i.e. the calm zone, the generation zone impacted by working face and the historical generation zone. After that, based on the horizontally zoning model, a method is developed to determine the displacement angle using the microseismic monitoring data, which has been verified in the Dongjiahe Coal Mine. © 2017 Elsevier Ltd

Xia W.,Dalian University of Technology | Cao M.,University of Groningen
Automatica | Year: 2017

In-depth understanding of the spectral properties of grounded Laplacian matrices is critical for the analysis of convergence speeds of dynamical processes over complex networks, such as opinion dynamics in social networks with stubborn agents. We focus on grounded Laplacian matrices for directed graphs and show that their eigenvalues with the smallest real part must be real. Lower and upper bounds for such eigenvalues are provided utilizing tools from nonnegative matrix theory. For those eigenvectors corresponding to such eigenvalues, we discuss two cases when we can identify the vertex that corresponds to the smallest eigenvector component. We then discuss an application in leader–follower social networks where the grounded Laplacian matrices arise naturally. With the knowledge of the vertex corresponding to the smallest eigenvector component for the smallest eigenvalue, we prove that by removing or weakening specific directed couplings pointing to the vertex having the smallest eigenvector component, all the states of the other vertices converge faster to that of the leading vertex. This result is in sharp contrast to the well-known fact that when the vertices are connected together through undirected links, removing or weakening links does not accelerate and in general decelerates the converging process. © 2017 Elsevier Ltd

Dong D.,Dalian University of Technology | Dong C.,Dalian University of Technology
Journal of Non-Crystalline Solids | Year: 2017

In the present report, the composition interpretation procedures based on the cluster-plus-glue-atom model are explicitly elucidated to simplify the understanding of the complicated chemistries of metallic glasses, via example of a well-known binary bulk metallic glass (BMG) Cu64Zr36. The key step of deriving the right cluster that enters into the cluster formula, termed the principal cluster, is emphasized, including defining the nearest-neighbor cluster and determining the principal cluster that is most representative for the phase structure. Clusters in the Cu8Zr3 phase structure, devitrified from glassy Cu64Zr36, are precisely identified according to a newly developed criterion based on Friedel oscillation. The principal cluster is then determined as [Cu-Cu7Zr5] for its fairly large cluster separation, as well as for the pronounced spherical periodicity order in the radial atomic density distribution profile. After matched with one Cu as glue atom, a 24-electron chemical unit [Cu-Cu7Zr5]Cu = Cu64.3Zr35.7 is formulated that explains perfectly the experimental Cu64Zr36 BMG. Via this specific example, detailed steps towards composition design of BMGs are established. © 2017 Elsevier B.V.

Liu W.,Dalian University of Technology | Li Q.,Dalian University of Technology
PLoS ONE | Year: 2017

Using the spectrum data for quality prediction always suffers from noise and colinearity, so variable selection method plays an important role to deal with spectrum data. An efficient elastic net with regression coefficients method (Enet-BETA) is proposed to select the significant variables of the spectrum data in this paper. The proposed Enet-BETA method can not only select important variables to make the quality easy to interpret, but also can improve the stability and feasibility of the built model. Enet-BETA method is not prone to overfitting because of the reduction of redundant variables realized by elastic net method. Hypothesis testing is used to further simplify the model and provide a better insight into the nature of process. The experimental results prove that the proposed Enet-BETA method outperforms the other methods in terms of prediction performance and model interpretation. © 2017 Liu, Li. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.

Wang L.,Inner Mongolia University | Li A.,Dalian University of Technology | Chang Y.,National Marine Environmental Monitoring Center
Water Research | Year: 2017

Hydrothermal treatment is an effective method to enhance the deep dewaterability of excess sludge with low energy consumption. In this study, an insight into the relationship between enhanced dewaterability and structural properties of the produced hydrothermal sludge was presented, aiming at better understanding the effect of hydrothermal process on excess sludge dewatering performance. The results indicated that hydrothermal effect induced the transformation of surface water to interstitial and free water by lowering the binding strength between adjacent water and solid particles and that free water became the main form for moisture existence in hydrothermal sludge as temperature was higher than 180 °C. Increase in temperature of hydrothermal treatment generated a significant size reduction of sludge flocs but treated sludge with a higher rigidity, which not only strengthened the network of hydrothermal sludge but also destroyed the binding of EPS with water. Hydrothermal process caused crevice and pore structures of excess sludge to disappear gradually, which was a main driving force of water removal as temperature was below 150 °C. With the temperature of hydrothermal treatment exceeding 180 °C, the morphology of hydrothermal sludge became rough which linked closely to the solid precipitation of condensation polymerization, and further became smooth at higher temperature (210 °C) due to the coal-like structures with higher aromaticities, indicating that hydrothermal reaction pathways began to play a main role in enhanced dewaterability. Hydrothermal treatment led to more alkyl and aromatic carbon, but lower O-alkyl, carboxyl and carbonyl carbon. © 2017 Elsevier Ltd

Afzal S.,Dalian University of Technology | Quan X.,Dalian University of Technology | Zhang J.,Dalian University of Technology
Applied Catalysis B: Environmental | Year: 2017

Mesoporous nanocast perovskites (NC-LaMnO3 and NC-LaFeO3) were synthesized by nanocasting technique using SBA-15 as a template and for the first time they were used in catalytic ozonation of 2-chlorophenol. For the purpose of comparison, uncast counterpart perovskites (CA-LaMnO3 and CA-LaFeO3) as well as Mn3O4 and Fe2O3 were also prepared by conventional citric acid assisted route. Nanocast perovskites possessed high specific surface area and large pore dimensions than uncast perovskites. Catalytic activity in terms of TOC removal followed the order of NC-LaMnO3 > NC-LaFeO3 > CA-LaMnO3 > CA-LaFeO3 > Mn3O4 > Fe2O3 > O3 with 80, 68, 50, 43, 39, 33% and 25% respectively. A detailed study is conducted to discuss the mechanism of catalytic ozonation of selected NC-LaMnO3 perovskite by using organic and inorganic hydroxyl radical's quenchers, FTIR, florescence spectroscopy, EPR, ATR-FTIR, XPS, LSV, H2O2 detection, Raman spectroscopy, TPR-H2, Rct value calculation, ozone utilization efficiency and ozone decomposition. It was found that hydroxyl radicals rather than surface peroxide, surface atomic oxygen, superoxide and singlet oxygen were the reactive oxygen species contributed to high catalytic activity. Moreover, high surface area as well as open porous structure of nanocast perovskites were believed to enhance the catalytic activity by surface reaction and easy access of reactants to the active sites. © 2017 Elsevier B.V.

Chen Y.,CAS Research Center for Eco Environmental Sciences | Wu Y.,CAS Research Center for Eco Environmental Sciences | Sun B.,Dalian University of Technology | Liu S.,CAS Research Center for Eco Environmental Sciences | Liu H.,Beijing University of Chemical Technology
Small | Year: 2017

Emerging nanotechnologies show unprecedented advantages in accelerating cancer theranostics. Among them, two-dimensional nanomaterials (2DNMs) represent a novel type of material with versatile physicochemical properties that have enabled a new horizon for applications in both cancer diagnosis and therapy. Studies have demonstrated that 2DNMs may be used in diverse aspects, including i) cancer detection due to their high propensity towards tumor markers; ii) molecular imaging for guided tumor therapies, and iii) drug and gene loading, photothermal and photodynamic cancer therapies. However, their biomedical applications raise concerns due to the limited understanding of their in vivo metabolism, transformation and possible toxicities. In this comprehensive review, the state-of-the-art development of 2DNMs and their implications for cancer nanotheranostics are presented. The modification strategies to enhance the biocompatibility of 2DNMs are also reviewed. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim

Li H.,Dalian University of Technology | Tsiaras A.,nok9 AB | Lau B.K.,Lund University
IEEE Transactions on Antennas and Propagation | Year: 2017

Measuring multiple-input multiple-output (MIMO) specific absorption rate (SAR) is an important part of mobile handset evaluation, following the introduction of uplink MIMO transmission schemes in long-term evolution advanced systems. However, the measurement of MIMO-SAR is complex and time consuming. In this communication, six unique dual-antenna mobile handsets, including both typical and novel designs, are analyzed to determine the dependence of MIMO-SAR on antenna configuration and correlation. It is found that, for certain antenna configurations, the location of the maximum MIMO-SAR and the corresponding relative phase between the ports can be predicted. This can be applied to drastically reduce measurement time. In addition, dual antennas with low envelope correlation coefficients in the radiation patterns also offer near-orthogonal electric near fields. This leads to smaller MIMO-SAR than stand-alone SAR (S-SAR) over all relative phases, making MIMO-SAR measurement unnecessary. The results also provide guidelines for designing multi-antenna handsets with low SARs. For verification, the S-SAR and MIMO-SAR at a relative phase of 0° were measured for several prototypes. The measured SAR distributions showed good agreement with the simulated ones. © 1963-2012 IEEE.

Wei G.,Dalian University of Technology | Quan X.,Dalian University of Technology | Chen S.,Dalian University of Technology | Yu H.,Dalian University of Technology
ACS Nano | Year: 2017

Theoretical permeability of membrane is inversely proportional to its thickness, which indicates ultrathin membranes will be extremely permeable. Inspired by the atomic thickness of graphene, herein we report a four-layered graphene membrane with a thickness of about 2 nm. The ultrathin membrane is facilely fabricated by directly punching a complete graphene sheet through selective removal of some carbon atoms with metal oxide nanoparticles at high temperature. Their perpendicular pore channels spanning the whole thickness could, to a great extent, reduce hydrodynamic resistance for water transport. Experimental tests have revealed a flux of up to 4600 L m-2 h-1 of the membranes with a pore size of 50 nm and pore density of 1.0 × 107 cm-2 at a pressure of 0.2 bar. This flux is 40-400 times higher than those of conventional ceramic membranes and track-etched membranes. The enhancement in water permeance is attributed to their atomic thickness and straight pore channels. High selectivity is also evidenced by selective separation of nanospheres with their narrowly distributed pores. These atomic-thin graphene membranes, in view of their outstanding permeability and selectivity, possess great potential as future advanced membranes and may inspire the design and development of other innovative membranes. © 2017 American Chemical Society.

Cui Y.,Dalian University of Technology | Liu J.,Dalian University of Technology
Tetrahedron Letters | Year: 2017

A novel compound was designed and synthesized by connecting a dicyanobenzene acceptor and two 9,9-dimethyl-9,10-dihydroacridine donors to the 1,3,5-position of a phenyl ring by meta-position connection. This compound, which is a novel emitter for OLED devices, exhibits preferable heat stability. Moreover, the energy gap between its singlet and triplet states is as small as 0.04 eV, resulting in this molecule possesses thermally activated delayed fluorescence. Therefore, the corresponding device showed efficient electroluminescent performances. The maximum external quantum efficiency, maximum current efficiency, maximum power efficiency and maximum luminance were 16.5%, 40.8 cd A−1, 45.8 lm W−1 and 5120 cd m−2, respectively. In addition, the CIEx,y only changed from (0.22, 0.38) to (0.22, 0.39) over the entire operating voltage range, which confirms that the device possesses highly stable chromaticity with respect to the current density. Based on these experimental results, meta-connected type structures may provide a new approach for developing high-performance TADF emitters for OLED applications. © 2017 Elsevier Ltd

Zhao N.,Dalian University of Technology | Cui X.,Dalian University of Technology
Physica A: Statistical Mechanics and its Applications | Year: 2017

Social networks exhibit strong community structure. Many researches have been done to explore the impacts of community structure on information diffusion but few combined with human behaviors together. In this paper, we focus on how the individual interests’ changing behavior impacts the dynamics of information propagation. Firstly, we propose an information dissemination model considering both the community structure and individual interest shift where social reinforcement and time decaying are taken into account. The accuracy of the model is evaluated by comparing the simulation and theoretical results. Further, the numerical results illustrate that both the community structure and the interests changing behavior have effects on the outbreak size of the information dissemination. Specially, lower modularity and higher community connection density will accelerate the speed of information propagation especially when the information maximal lifetime is shorter. In addition, the changes of individual interests in the message have a great impact on the final density of the received through increasing or decreasing the number of satisfied individuals directly. What is more, our findings suggest that when the modularity of the network is higher and the community clustering coefficient is lower individual interest shift behavior will have a heavier effect on the spread scope. © 2016 Elsevier B.V.

Feng T.-H.,Dongbei University of Finance and Economics | Xia X.-C.,Dalian University of Technology
Optical Materials Express | Year: 2017

Arsenic doped p-type ZnO films are prepared by the photo-assisted metal organic chemical vapor deposition method. Using the photo-assisted technique, the acceptor activation process is simplified. The arsenic doping level, which decides the carrier distribution, could be controlled by changing the thickness of the pre-deposited GaAs layer. The crystal and optical quality of the ZnO films is good. The acceptor is AsZn-2VZn. Its ionization energy could be slightly reduced by increasing the arsenic doping level. This finding is very helpful to improve the hole concentration. Our experiments provide a new method to grow high performance p-type ZnO based photoelectric devices. © 2017 Optical Society of America.

Chao D.,Dalian University of Technology | Zhang Y.,Dalian University of Technology
Sensors and Actuators, B: Chemical | Year: 2017

Four terpyridine–based Cu2+ complexes with different hydrophilic or hydrophobic groups were synthesized and developed for the detection of Hcy in water based on the aggregation of copper complexes. It is found that these terpyridine–based Cu2+ complexes were reduced by homocysteine (Hcy) along with generation of luminescent four–coordinated Cu+ species. Terpyridine–based Cu2+ complexes bearing hydrophilic groups such as [Ru(bpy)3]+ exhibited turn–on luminescence at 635 nm in the presence of Hcy and then the luminescence would be quenched in 1 min due to rapid oxidation of Cu+ species by dissolved oxygen in water, resulting in cyclic detection of Hcy. However, complexes bearing more hydrophobic groups exhibited stronger and much more durable luminescence over 10 min upon addition of Hcy in water because of aggregation of generated Cu+ species which were beneficial to enhance inhibition of oxygen–induced quenching. A 1500–fold luminescence intensity enhancement at 603 nm was observed in the detection of Hcy using the [Ir(ppy)2(bpy)]+ modified terpyridine–based Cu2+ complex. The detection process was fast within 2 min and limit of detection (LOD) was found to be ∼10.1 nM. Finally, terpyridine–based Cu2+ complexes were successfully applied in cell imaging. © 2017

Liu D.,Dalian University of Technology | Liu D.,State Key Laboratory of Robotics and Systems HIT | Cong M.,Dalian University of Technology | Cong M.,State Key Laboratory of Robotics and Systems HIT | Du Y.,University of British Columbia
IEEE Transactions on Industrial Electronics | Year: 2017

This paper presents a robotic behavior planning method under uncertainty based on biology-inspired episodic memory. Adaptive behavior planning, prediction and reasoning are achieved between tasks, environment, and threats. Through building a novel episode model and introducing the activation and stimulation mechanism of state neurons, the framework of an episodic memory-driving Markov decision process (EM-MDP) is proposed for incremental self-learning of robotic experience and cognitive behavior planning. Two main challenges in robot behavior control under uncertainty are addressed: high computational complexity and perceptual aliasing. The approach for robotic global planning and behaviors sequence prediction based on the EM-MDP is developed utilizing neuron synaptic potential. A local behavioral planning method based on risk function and feasible paths is employed to achieve path optimization and behavior reasoning under the condition of imperfect memory. Robot can evaluate the past events sequence, predict the current state, and plan the desired behaviors. The proposed method is evaluated in several real-life environments for a mobile robot system. The robot system is able to successfully produce solutions in general scenarios under uncertainty. © 2016 IEEE.

Zhong F.,Dalian University of Technology | Zhao J.,Dalian University of Technology
Dyes and Pigments | Year: 2017

A series of anthracene derivatives with 9,10-substituents were prepared as triplet acceptors/emitters for triplet-triplet-annihilation (TTA) upconversion. Different linkages of C[sbnd]C single bonds and C[tbnd]C triple bonds were used to tune the singlet and triplet state energy levels, which may enhance the TTA upconversion. The study of the photophysical properties of the compounds indicates that the C[sbnd]C linker does not alter the T1 state energy level substantially, whereas the C[tbnd]C linker significantly reduced the T1 state energy levels. With nanosecond transient absorption spectroscopy, the intermolecular triplet-triplet-energy-transfer (TTET) process was studied. The lack of the upconversion for some anthracene derivatives was attributed to the inappropriate T1 energy levels thus the lack of TTET. On the other hand, different upconversion quantum yields were observed for some acceptors, although the TTET processes are similar. This result is due to the different TTA. These studies will be useful for future development of the TTA upconversion and for study of the triplet state properties of organic chromophores. © 2016 Elsevier Ltd

Sun J.,CAS Shanghai Institute of Organic Chemistry | Luo L.,Dalian University of Technology | Luo Y.,Dalian University of Technology | Deng L.,CAS Shanghai Institute of Organic Chemistry
Angewandte Chemie - International Edition | Year: 2017

N-Heterocyclic carbene based pincer ligands bearing a central silyl donor, [CSiC]-, have been envisioned as a class of strongly σ-donating ligands that can be used for synthesizing electron-rich transition-metal complexes for the activation of inert bonds. However, this type of pincer ligand and complexes thereof have remained elusive owing to their challenging synthesis. We herein describe the first synthesis of a CSiC pincer ligand scaffold through the coupling of a silyl-NHC chelate with a benzyl-NHC chelate induced by one-electron oxidation in the coordination sphere of a cobalt complex. The monoanionic CSiC ligand stabilizes the CoI dinitrogen complex [(CSiC)Co(N2)] with an unusual coordination geometry and enables the challenging oxidative addition of E-H bonds (E=C, N, O) to CoI to form CoIII complexes. The structure and reactivity of the cobalt(I) complex are ascribed to the unique electronic properties of the CSiC pincer ligand, which provides a strong trans effect and pronounced σ-donation. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Hong X.,Dalian University of Technology | Sun X.,Dalian University of Technology
Proceedings of SPIE - The International Society for Optical Engineering | Year: 2016

Optical detection of nanoparticle with ultra-high sensitivity plays an important role in bio- / nano- and their relative research fields. In our recently developed method, each single particle exhibits unique 4-lobes pattern both in the amplitude and phase images respectively, based on which we explored the possibility of resolution improvement by a particle pair. In this paper two polystyrene beads at the diameter of 100nm were employed with the gap distance ranging from 100-400nm. The amplitude and phase images of the particle pair were simulated by FDTD solver. The images are sensitive to geometrical parameters of the two particles, such as gap distance and direction. The simulation results lead to a resolution of 100nm. © 2016 SPIE.

Xue X.,Dalian University of Technology | Wang Y.,Dalian University of Technology | Han F.-S.,CAS Changchun Institute of Applied Chemistry
Chemical Communications | Year: 2017

The design and preparation of a chiral Pt nanocatalyst system possessing thermoregulated phase-separation property and its application in recyclable asymmetric hydrogenation of α-ketoesters are presented. © The Royal Society of Chemistry.

Jin Q.,Dalian University of Technology | Yao W.,Dalian University of Technology
Aerospace Science and Technology | Year: 2017

In this paper, an efficient improved C0-type global–local model (IGLM) considering transverse normal strain is proposed to study the hygrothermal response of thick cross-ply laminated composite plates. Based on the interlaminar continuity conditions of in-plane displacement and transverse shear stresses, layer-dependent variables could be reduced. Employing shear stress free condition at the upper and the lower surfaces, derivatives of transverse displacement are eliminated from the displacement field, so that C0 interpolation functions are only required for the finite element implementation. As a result, the number of variables is independent of the number of layers of the laminate. To assess the proposed model, the classical quadratic eight-node isoparametric element is presented, in which the interelement C0 continuity conditions are satisfied. Comparing the results from available three-dimensional elasticity theory and those computed from the ninth-order model, it is found that the simple C0 finite elements could produce promising deformations and stresses for thick cross-ply laminated composite plates with different boundary conditions under hygrothermal loadings. © 2017 Elsevier Masson SAS

Wang Y.,Dalian University of Technology | Kang Z.,Dalian University of Technology
International Journal for Numerical Methods in Engineering | Year: 2017

This paper presents a level set-based shape and topology optimization method for conceptual design of cast parts. In order to be successfully manufactured by the casting process, the geometry of cast parts should satisfy certain moldability conditions, which poses additional constraints in the shape and topology optimization of cast parts. Instead of using the originally point-wise constraint statement, we propose a casting constraint in the form of domain integration over a narrowband near the material boundaries. This constraint is expressed in terms of the gradient of the level set function defining the structural shape and topology. Its explicit and analytical form facilitates the sensitivity analysis and numerical implementation. As compared with the standard implementation of the level set method based on the steepest descent algorithm, the proposed method uses velocity field design variables and combines the level set method with the gradient-based mathematical programming algorithm on the basis of the derived sensitivity scheme of the objective function and the constraints. This approach is able to simultaneously account for the casting constraint and the conventional material volume constraint in a convenient way. In this method, the optimization process can be started from an arbitrary initial design, without the need for an initial design satisfying the cast constraint. Numerical examples in both 2D and 3D design domain are given to demonstrate the validity and effectiveness of the proposed method. © 2017 John Wiley & Sons, Ltd.

He S.,Dalian University of Technology | Hu X.,Dalian University of Technology
Proceedings - 2016 9th International Symposium on Computational Intelligence and Design, ISCID 2016 | Year: 2017

This paper focuses in particular on the problem of Chinese characters recognition in natural scenes. Due to large variation in fonts, sizes, illumination, cluttered backgrounds, geometric distortions, etc., scene text recognition in the wild is a challenging problem. We proposed a novel method which based on Integral Channel Feature and pooling technology to extract informative features from scenes images. We concatenated many different low-level features and selected typically features to represent the Chinese characters. In this work, we make use of Support Vector Machines as the classifier, and rank the features by the weights of training model in LinearSVM. Thus features representation of characters is compact and it is effective to express distinctive spatial structures of text character. At the same time, for comparative purpose, we evaluated approach extensively on two standard dataset (ICHAR03, Char74K). Because of the absence of Chinese character datasets, we took 311 photos by cellphone and digit camera in Guangzhou and cropped them to pieces manually to form two Chinese datasets. Our experiment results denote that our proposed technology was performed better than the current state-of-the-art methods. © 2016 IEEE.

Han M.,Dalian University of Technology | Zhang Y.,Dalian University of Technology
2016 IEEE International Conference on Systems, Man, and Cybernetics, SMC 2016 - Conference Proceedings | Year: 2016

We studied finite-time function projective synchronization of unknown delayed Cohen-Grossberg neural networks with stochastic disturbance. A hybrid control scheme is proposed to let the drive-response networks synchronize and have a scaling function relation in finite time with topology identification by using the finite-time stability theory. Furthermore, we estimate the high bounds of the synchronization settling time. Finally, the corresponding numerical simulation and its application in secure communication are provided to verify the correctness of the method we proposed. © 2016 IEEE.

Wang C.S.,Dalian University of Technology | Hu P.,Dalian University of Technology
Shell Structures: Theory and Applications - Proceedings of the 10th SSTA 2013 Conference | Year: 2014

The quasi-conforming technique has achieved great success in linear and nonlinear field of finite element analysis over past several decades. The formulation of quasi-conforming element is simple and flexible, unifying the conforming and non-conforming finite element method. Different from the traditional finite element method, the strain-displacement equations are weakened as well as the equilibrium equations in quasi-conforming technique. Many excellent quasi-conforming elements have been constructed and applied widely in engineering analysis. In this paper, the formulation of the quasi-conforming element is introduced briefly and the choice of initially assumed displacement/strain and the interpolation functions are discussed. Some recent work of quasi-conforming plate/shell elements are summarized. The research on quasi-conforming technique is an original and fundamental work, which contributes to the development of computational mechanics.

Li L.,Dalian University of Technology | Cui P.,Dalian University of Technology
Journal of Engineering Mechanics | Year: 2017

In practical engineering, a tuned mass damper (TMD) inherently exhibits nonlinear behavior owing to its large displacement or the application of a limiting stopper. This paper studies the control performance of a TMD when nonlinear behavior caused by nonlinear spring stiffness is taken into account for practical application. A new analysis and design method of a nonlinear TMD is proposed. Based on the analysis of the nonlinear TMD, a modified design of a nonlinear TMD is presented according to the jump frequency. The analytic solutions of the jump frequency that can be used to design the nonlinear TMD are obtained. The results of the simulation prove that the proposed design method considering the nonlinear behavior of the TMD will improve the control performance of the nonlinear TMD compared to the linear-based design method. © 2017 American Society of Civil Engineers.

Hong X.,Dalian University of Technology | Jin Z.,Dalian University of Technology
Proceedings of SPIE - The International Society for Optical Engineering | Year: 2016

Gold nanoparticles exhibit unique plasmonic optical properties in visible to near infrared band. Especially the coupling effect existing at the gap between a closely linked particle pair can make the local field strongly enhanced. These properties make gold particles more attractive to be employed as molecular probes in biomedical related fundamental and clinical researches. However in the bio-system exist many large molecules or groups, whose optical signals can strongly depress the gold particles without detectable. In this paper, we proposed a method to extract the targets which are labelled by gold dimer pairs from large scattering background. © 2016 SPIE.

Wang G.,Dalian University of Technology | Ma Z.,Dalian University of Technology
Computers and Geotechnics | Year: 2017

A reliability analysis method based on the combination of the first-order reliability method (FORM) and hybrid particle swarm optimization (SACPSO) is presented for the reliability optimization calculation. The new reliability method, named as SACPSO-FORM, can be utilized for those complex reliability problems with correlated non-normal variables and implicit performance functions. Three examples are performed to verify its validation, and stability reliability analysis on the complicated rock foundation of a practical gravity dam is demonstrated. The results show that the proposed method is accurate, stable, flexible and efficient for reliability analysis in engineering applications. © 2016 Elsevier Ltd

Guo J.,Dalian University of Technology | Zhao N.,Dalian University of Technology | Yu F.R.,Carleton University | Liu X.,Dalian University of Technology | Leung V.C.M.,University of British Columbia
IEEE Transactions on Wireless Communications | Year: 2017

Anti-jamming interference alignment (IA) is an effective method for battling adversarial jammers for IA networks. Nevertheless, the number of antennas may not be enough to make it feasible in anti-jamming IA. Besides, the abundant power from the jammers and interferences, which used to be deemed as a harmful factor, can be exploited for energy harvesting (EH) by the legitimate users as a power supply. Thus, in this paper, we propose an anti-jamming opportunistic IA (OIA) scheme with wireless EH, which optimizes the transmission rate and EH together. In the proposed scheme, to make the anti-jamming IA network feasible, we select some of the users to transmit information at each time slot, and EH is performed by the other unselected users. Furthermore, to improve the performance of the proposed scheme, EH is also performed by the selected users, and the transmit power and power partition coefficient are jointly optimized to minimize the total transmit power of the OIA network. To reduce the computational complexity of the joint optimization, a suboptimal algorithm is also developed with much lower complexity. Extensive simulation results are presented to show the effectiveness of the proposed anti-jamming OIA scheme with wireless EH. © 2016 IEEE.

Hong X.,Dalian University of Technology | Wang C.,Dalian University of Technology
Proceedings of SPIE - The International Society for Optical Engineering | Year: 2016

Noble metallic nanoparticle exhibits unique optical properties in visible to near infrared band when its localized surface plasmon resonance is excited. For example a sharp absorption peak at 509nm for a gold nanoparticle at the diameter of 60nm. The plasmonic properties heavily depend on its geometrical structure. In this paper, we theoretically calculate the optical properties of a single nanoparticle with different structure such as solid and core-shell. The simulation results show that the core-shell structure can reach a much broader tunable band and in which the shell thickness plays a dominant role. Further by employing a core-shell pair, more flexible properties can be reached. © 2016 SPIE.

Wang H.,Dalian University of Technology | Liao J.,Knowledge Processing and Networked Manufacturing Key Laboratory in Universities of Hunan Province
Proceedings - 9th International Conference on Measuring Technology and Mechatronics Automation, ICMTMA 2017 | Year: 2017

A semi-lattice based activity model has been introduced to infer human daily activity within smart environment. For the purpose of improving the accuracy of activity recognition as well as to further study the layer function in lattice structure, we've explored the relationship between sensor and activity, and the relationship between different activities in this paper. Through the analysis of relations we can know that the minimal requirement of sensor/object for a lattice based recognizing model is three. Moreover we find out that the lattice structure for multi-activity recognition can minimize the overlapping between different activities and obtain a comparable accuracy with the process of single activity recognition. © 2017 IEEE.

Wang Y.,Dalian University of Technology | Wang Y.,Dalian University
Proceedings - 9th International Conference on Measuring Technology and Mechatronics Automation, ICMTMA 2017 | Year: 2017

The calculation results of the embedded real-time system correctness depends not only on the logical system, and the results also spent time, the system must ensure in response to external events in a predictable period of time. Worst Execution Time (the worst case execution time (Case) is the maximum execution time of the program in the process of running. It plays a very important role in the research of real time scheduling, task priority arbitration, resource conflict arbitration, inter task communication and hardware / software partitioning. This paper focuses on the specific hardware platform (ARM7TDMI processor), the worst case Garfield system MP3 decoding program execution time (WCET) were evaluated on the MP3 decoding program optimization and give objective evaluation, but also provide important basis for the division of hardware and software of MP3 module. The worst case execution time (WCET) calculation is mainly related to two aspects: the high level analysis (Analysis High-Level) and the underlying modeling (Modeling Low-Level). High level analysis is to analyze the program structure in a high level language, find out the sequence of instructions in the worst case, while the bottom is built hardware model in assembly environment, the worst case has a known sequence of instructions execution time. The complexity of the WCET calculation limits the size of the analyzed program and the accuracy of the calculation. This paper introduces an effective method to calculate the worst-case execution time (WCET), and develops a path analysis tool CRYINGCAT. The path analysis tools to get the instruction execution time from the bottom of the model, the anti mark flow graph analysis control extracted from the top (Control Flow Graph), and then use the containing control execution time information flow diagram to establish the integer linear programming model, and finally through the worst case solving integer linear programming model to obtain the execution time of the program (WCET). Prior informed system program in the worst case execution time (Worst-Case Execution, Time, WCET) is the design and verification of real-time scheduling and schedulability analysis of the premise, but also to determine whether the periodic tasks meet their performance goals, in order to find the basis system performance bottleneck. This paper summarizes the analysis methods of WCET program, describes the definition and composition of WCET analysis, summarize the program flow fact analysis method, and points out the research program flow fact analysis and WCET analysis of the existing problems. © 2017 IEEE.

Wang M.,Zhejiang University | Wang W.,Dalian University of Technology | Zhang Z.,Peking University
Archive for Rational Mechanics and Analysis | Year: 2017

In this paper, we consider the solutions of the relaxed Q-tensor flow in (Formula presented.) with small parameter (Formula presented.). We show that the limiting map is the so-called harmonic map flow. As a consequence, we present a new proof for the global existence of a weak solution for the harmonic map flow in three dimensions as in [18, 23], where the Ginzburg–Landau approximation approach was used. © 2017 Springer-Verlag Berlin Heidelberg

Wu Q.,Dalian University of Technology | Zhang Z.,Dalian University of Technology
Journal of Materials Engineering and Performance | Year: 2017

Friction stir welding of AA6082-T6 with different welding parameters is simulated by computational fluid dynamics model. Monte Carlo method is further used to simulate the grain growth with consideration of the precipitation effects. The comparison with experimental observations can validate the proposed grain growth model with the precipitate effects. Results indicate that the final grain size can be increased by 39.7% in the nugget zone when the volume fraction of precipitation is decreased from 0.8 to 0.2% after welding. Both the grain growth speed and the final grain size on the top surface are higher than the bottom surface. The increase in the welding temperature caused by the increase in the rotation speeds or the axial forces can lead to lower volume fractions of precipitations and then lead to larger grain sizes . © 2017 ASM International

Xia L.,Dalian University of Technology | Liu Q.,Dalian University of Technology
Computational Materials Science | Year: 2017

Grand canonical Monte Carlo simulations were conducted at T = 77 and 298 K to predict adsorption isotherms for hydrogen in two aluminum-based Metal-Organic Frameworks (MOFs) with the same framework topology, MOF-519 and MOF-520. We explored the effects of pressure on hydrogen adsorption in both materials. In addition, the adsorption mechanism as well as the preferred adsorption sites in both materials were also studied. The GCMC results showed that MOF-519 exhibited an excellent storage capacity for H2 at lower pressure, which can be attributed to its high adsorption heat. While at higher pressure, MOF-520 showed much better hydrogen adsorption performance due to its high specific surface area and pore volume. The results also indicated that the strongest adsorption sites for H2 in MOF-519 were near the oxygen atoms of bicarboxylic linkers, while aluminum-oxygen clusters were preferential adsorption sites for hydrogen in MOF-520. © 2016 Elsevier B.V.

Han M.,Dalian University of Technology | Zhang C.,Dalian University of Technology
Neurocomputing | Year: 2017

The last few years have witnessed the success of sparse representation in hyperspectral image classification. However, the high computational complexity brings some worries to its applications. In this paper, a novel sparse representation based feature extraction algorithm, called discriminant sparsity preserving embedding (DSPE), is proposed by constructing a sparse graph and applying it to the graph-embedding framework. The proposed algorithm encodes supervised information mainly in stage of sparse graph construction, in which only the training samples in the same class are used to calculated the reconstructive coefficients during sparse reconstruction. An approach combining l1-norm and l2-norm is applied to solve the reconstruction weights, where l1-norm ensures the sparsity of the graph weights, l2-norm shrinks the weight coefficients to make the construction more stable and alleviate the reconstruction errors possibly caused by small-size training samples. On the premise of satisfied classification results, here a spectral-spatial classification strategy which takes spatial information into consideration is used to evaluate the efficiency of the proposed algorithm. Experiments on the Indian Pines and Pavia University hyperspectral image datasets demonstrate the superiority of the proposed algorithm. © 2017

Yu H.,Dalian University of Technology | Guo Q.,Dalian University of Technology | Zheng S.,Dalian University of Technology
Nonlinear Analysis: Real World Applications | Year: 2017

This paper considers the attraction–repulsion chemotaxis system: ut=Δu−χ∇⋅(u∇v)+ξ∇⋅(u∇w), 0=Δv+αu−βv, 0=Δw+γu−δw, subject to the non-flux boundary condition in a smooth bounded domain Ω⊂R2, with χ,ξ≥0, α,β,γ,δ>0. We establish the finite time blow-up conditions for nonradial solutions that the finite time blow-up occurs at x0∈Ω whenever ∫Ωu0(x)dx>8π/(χα−ξγ) with χα−ξγ>0, under ∫Ωu0(x)|x−x0|2dx sufficiently small. This does agree with the known blow-up conditions for radial solutions of the same model. The previous blow-up conditions for nonradial solutions are more complicated involving a classification to the sign of δ−β. © 2016 Elsevier Ltd

Chen C.-J.,Dalian University of Technology | Li S.-Z.,Dalian University of Technology
Physics of Plasmas | Year: 2017

The species, N2(C), N2(B), and N2 +(B), in the post-discharge of a nitrogen microwave induced discharge (2.45 GHz) at atmospheric pressure are investigated by means of optical emission diagnosis of the spatial distribution of emission intensities of N2(C-B), N2(B-A), and N2 +(B-X) transitions. Correspondingly, the post-discharge can be divided into two distinct regimes, the early and late afterglows. It is found that not only atomic N survives in the late afterglow regime of the post-discharge but also the N2 + ions are produced even far from the microwave launcher. This is attributed to the fact that the vibrationally excited N2(X, υ) and ground state N(4S) with a long lifetime can be conveyed at far distance and act as the precursor for generating N2 + ions locally. © 2017 Author(s).

Liu J.,Dalian University of Technology | Xia H.,National University of Singapore | Lu L.,National University of Singapore | Xue D.,Dalian University of Technology
Journal of Materials Chemistry | Year: 2010

Anisotropic column-shaped porous Co3O4 nanocapsules were successfully synthesized via a solvothermal route using poly(vinyl pyrrolidone) (PVP) as capping reagent and final heat treatment in air. These anisotropic polycrystalline nanocapsules with the length of ∼1 μm and the diameter of ∼400 nm were characterized by X-ray powder diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM) methods. Detailed proof indicated that the process of CoCO3 precursor growth was dominated by a nucleation and growth, self-organization, and then Ostwald ripening growth mechanism. These column-shaped Co3O 4 nanocapsules integrate two beneficial features: hollow cavity and porous shell. When evaluated for Li-ion batteries, they exhibit high reversible capacity (over 1000 mA h g-1) and good cycle performance. © The Royal Society of Chemistry 2010.

Govindan K.,University of Southern Denmark | Zhu Q.,Dalian University of Technology | Kannan D.,Indian Institution of Industrial Engineering
International Journal of Production Economics | Year: 2012

Due to growing economic environment and the introduction of new technologies in marketing, another topic of great interest to logistics today is the use of contract or third party services. In the complicated business world, the company is involved in reuse, recycling, and remanufacturing functions using a third party logistics provider which has an impact on the total performance of the firm. In the development of the reverse logistics concept and practice, the selection of providers for the specific function of reverse logistics support becomes more important. After scanning the surplus of literatures, it was concluded that multiple dimensions and attributes must be used in the evaluation and selection of 3PRLP. The attributes play an important role in selecting a third party reverse logistics provider (3PRLP). Interpretive structural modeling (ISM) methodology is adopted in this model, which can be used for identifying and summarizing relationships among specific attributes for selecting the best third party reverse logistics provider among the 'n' 3PRLPs. © 2012 Elsevier B.V. All rights reserved.

Kang Z.,Dalian University of Technology | Wang Y.,Dalian University of Technology
Computer Methods in Applied Mechanics and Engineering | Year: 2013

This paper presents a novel topology description model for topology optimization problems with embedded movable holes, combining the ability of the level set model for accurate geometrical description of the prescribed hole shapes, and the high efficiency of the material density-based method. By this means, any arbitrary hole shapes can be represented accurately and smoothly, while the topological changes can be easily handled by the material distribution model. An explicit mathematical expression is defined to obtain the actual structural layout by combing both models. Moreover, an effective model for the non-overlap constraint is proposed in a unified and systematic manner to avoid the overlaps between the holes and between each hole and the design domain boundary. Therein, the non-overlap constraint for all the embedded holes is imposed as a single explicit integral constraint over the design domain, thus avoiding the difficulties in the overlap detection of multiple arbitrary-shaped geometries. Such a non-overlap constraint is accurate and differentiable, facilitating an analytical design sensitivity analysis. Numerical examples are given to demonstrate the effectiveness and efficiency of the present method. © 2012 Elsevier B.V.

Wang C.,U.S. Food and Drug Administration | Wang Z.,Dalian University of Technology | Prows D.R.,University of Cincinnati | Wu R.,Pennsylvania State University
Briefings in Bioinformatics | Year: 2012

Genetic imprinting, by which the expression of a gene depends on the parental origin of its alleles, may be subjected to reprogramming through each generation. Currently, such reprogramming is limited to qualitative description only, lacking more precise quantitative estimation for its extent, pattern and mechanism. Here, we present a computational framework for analyzing the magnitude of genetic imprinting and its transgenerational inheritance mode. This quantitative model is based on the breeding scheme of reciprocal backcrosses between reciprocal F1 hybrids and original inbred parents, in which the transmission of genetic imprinting across generations can be tracked. We define a series of quantitative genetic parameters that describe the extent and transmission mode of genetic imprinting and further estimate and test these parameters within a genetic mapping framework using a new powerful computational algorithm. The model and algorithm described will enable geneticists to identify and map imprinted quantitative trait loci and dictate a comprehensive atlas of developmental and epigenetic mechanisms related to genetic imprinting. We illustrate the new discovery of the role of genetic imprinting in regulating hyperoxic acute lung injury survival time using a mouse reciprocal backcross design. © The Author 2011. Published by Oxford University Press.

Li J.,Beijing Normal University | Deng G.,Northeast Dianli University | Li H.,Dalian University of Technology | Zeng W.,Beijing Normal University
Information Sciences | Year: 2012

In this paper, we introduce an axiomatic definition of the similarity measure of intuitionistic fuzzy sets (IFS) that differs from the definition of Li [15]. The relationship between the similarity measure and the entropy of IFS is investigated in detail. Six theorems on how the similarity measure could be transformed into the entropy for IFS and vice versa are proposed based on their axiomatic definitions. Some formulas have been proposed to calculate the similarity measure and the entropy of IFS. Finally, sufficient conditions to transform the similarity measures to the entropy for IFS and vice versa are given. © 2011 Elsevier Inc. All rights reserved.

Qiu Y.,Dalian University of Technology | Chen X.,Dalian University of Technology | Liu H.,University of Surrey
IEEE Transactions on Power Electronics | Year: 2010

A new digital average current-mode control technique is proposed for dc-dc converters operation in discontinuous conduction mode. In contrast to the regulation of inductor current, this paper focuses on how the suitable charge current is feed to capacitor and load resistor directly. Using the principle of capacitor charge balance, the charge current reference in next switching cycle is predicted in order to drive the output voltage back to its nominal value quickly during transient conditions. The actual average charge current is estimated from a simplified algorithm, which can also be used to calculate the required duty ratio according to the charge current reference. This control technique features good dynamic performance and it is compliant with the performance constraints of digital integrated processor. The effectiveness of the proposed solution has been proved by the simulation and experimental results. © 2006 IEEE.

Yao R.,Dalian University of Technology | Yao R.,University of California at Davis
Journal of Advanced Transportation | Year: 2013

Short left-turn lanes are often channelized to improve capacity and level of service at signalized intersections. On the basis of previous achievements, this paper improves the joint optimization models for isolated signalized intersections with short left-turn lanes and aims to analyze the sensitivity of the optimization results to the parameters (critical cycle length and maximum short-lane length). To further clarify the effects of these models on traffic flow operations, several better optimization scenarios are simulated together with the existing one. The models and the methods are illustrated via the field data from Dalian, China. According to the analysis results, the optimum models and parameter values or ranges are recommended. Finally, the procedure of the model application is also proposed to apply in practice. Copyright © 2012 John Wiley & Sons, Ltd.

Wang R.,Dalian University of Technology | Wu Z.-G.,Dalian University of Technology | Shi P.,University of Adelaide | Shi P.,Victoria University of Melbourne
Information Sciences | Year: 2013

In this paper, the problem of output feedback stabilization is considered for a class of switched delay systems under asynchronous switching. When the switching signal of the switched controller involves delay, by constructing a novel Lyapunov functional which is allowed to increase during the running time of active subsystems with the mismatched controller, sufficient conditions for exponential stability are developed for a class of switching signals based on the average dwell time method. Moreover the stabilizing output feedback controllers are designed. Finally, an example is given to demonstrate the feasibility and effectiveness of the proposed design techniques. © 2012 Elsevier Inc. All rights reserved.

Olhoff N.,University of Aalborg | Niu B.,University of Aalborg | Cheng G.,Dalian University of Technology
International Journal of Solids and Structures | Year: 2012

The design of band-gap structures receives increasing attention for many applications in mitigation of undesirable vibration and noise emission levels. A band-gap structure usually consists of a periodic distribution of elastic materials or segments, where the propagation of waves is impeded or significantly suppressed for a range of external excitation frequencies. Maximization of the band-gap is therefore an obvious objective for optimum design. This problem is sometimes formulated by optimizing a parameterized design model which assumes multiple periodicity in the design. However, it is shown in the present paper that such an a priori assumption is not necessary since, in general, just the maximization of the gap between two consecutive natural frequencies leads to significant design periodicity. The aim of this paper is to maximize frequency gaps by shape optimization of transversely vibrating Bernoulli-Euler beams subjected to free, standing wave vibration or forced, time-harmonic wave propagation, and to study the associated creation of periodicity of the optimized beam designs. The beams are assumed to have variable cross-sectional area, given total volume and length, and to be made of a single, linearly elastic material without damping. Numerical results are presented for different combinations of classical boundary conditions, prescribed orders of the upper and lower natural frequencies of maximized natural frequency gaps, and a given minimum constraint value for the beam cross-sectional area. To study the band-gap for travelling waves, a repeated inner segment of the optimized beams is analyzed using Floquet theory and the waveguide finite element (WFE) method. Finally, the frequency response is computed for the optimized beams when these are subjected to an external time-harmonic loading with different excitation frequencies, in order to investigate the attenuation levels in prescribed frequency band-gaps. The results demonstrate that there is almost perfect correlation between the band-gap size/location of the emerging band structure and the size/location of the corresponding natural frequency gap in the finite structure. © 2012 Elsevier Ltd. All rights reserved.

Qiu Y.,Dalian University of Technology | Liu H.,University of Surrey | Chen X.,Dalian University of Technology
IEEE Transactions on Industrial Electronics | Year: 2010

This paper introduces a digital average current-mode control technique for pulsewidth modulation dcdc converters which only rely on voltage sampling. The proposed approach is to estimate inductor current using first-order discrete-time low-pass filter; therefore, the controller can calculate average inductor current in every switching cycle. As a novel technique of predictive average current control, it has been investigated by choosing an appropriate duty ratio to regulate valley inductor current first and then eliminating error between the estimated average inductor current and a reference current in succedent switching cycle. The algorithm is based on a two-loop control structure to achieve an accurate voltage regulation and is derived for three basic converters: buck, boost, and buckboost. The validity of the proposed approach has been demonstrated by simulation and experimental results on a dcdc boost converter. © 2006 IEEE.

Tang Y.-Y.,Dalian University of Technology | Tang Y.-Y.,University of Oregon | Lu Q.,Dalian University of Technology | Geng X.,U.S. National Institute on Drug Abuse | And 3 more authors.
Proceedings of the National Academy of Sciences of the United States of America | Year: 2010

The anterior cingulate cortex (ACC) is part of a network implicated in the development of self-regulation and whose connectivity changes dramatically in development. In previous studieswe showed that 3 h of mental training, based on traditional Chinese medicine (integrative body - mind training, IBMT), increases ACC activity and improves self-regulation. However, it is not known whether changes in white matter connectivity can result from small amounts of mental training. We here report that 11 h of IBMT increases fractional anisotropy (FA), an index indicating the integrity and efficiency ofwhite matter in the corona radiata, an important white-matter tract connecting the ACC to other structures. Thus IBMT could provide a means for improving self-regulation and perhaps reducing or preventing various mental disorders.

Dong G.,Zhejiang Normal University | Lu Q.,Dalian University of Technology | Zhou H.,Zhejiang Normal University | Zhao X.,Zhejiang Normal University
PLoS ONE | Year: 2011

Background:This study aimed to evaluate the roles of pathological disorders in Internet addiction disorder and identify the pathological problems in IAD, as well as explore the mental status of Internet addicts prior to addiction, including the pathological traits that may trigger Internet addiction disorder.Methods and Findings:59 students were measured by Symptom CheckList-90 before and after they became addicted to the Internet. A comparison of collected data from Symptom Checklist-90 before Internet addiction and the data collected after Internet addiction illustrated the roles of pathological disorders among people with Internet addiction disorder. The obsessive-compulsive dimension was found abnormal before they became addicted to the Internet. After their addiction, significantly higher scores were observed for dimensions on depression, anxiety, hostility, interpersonal sensitivity, and psychoticism, suggesting that these were outcomes of Internet addiction disorder. Dimensions on somatisation, paranoid ideation, and phobic anxiety did not change during the study period, signifying that these dimensions are not related to Internet addiction disorder.Conclusions:We can not find a solid pathological predictor for Internet addiction disorder. Internet addiction disorder may bring some pathological problems to the addicts in some ways. © 2011 Dong et al.

Zhai F.,Zhejiang Normal University | Mu P.,Dalian University of Technology
Applied Physics Letters | Year: 2011

We study the transport properties of Dirac fermions on the surface of a topological insulator attached with a spiral multiferroic oxide (SMO). For the spiral plane of the SMO parallel to the spiral axis and the surface normal, the proximity-induced exchange field causes a particle-hole asymmetry and a transmission gap near the Dirac point. The transmission gap interval depends on the spiral wave vector q. This fact together with the tunability of q by gate voltages indicates an electric switch with high on-off ratios. The dependence of the conductance on the orientation of the spiral plane is also examined. © 2011 American Institute of Physics.

Zhai F.,Zhejiang Normal University | Yang L.,Dalian University of Technology
Applied Physics Letters | Year: 2011

We investigate spin-dependent electronic transport through normal/strained/normal/ferromagnetic/normal graphene junctions. The substrate strain leads to opposite shifts of the K and K′ valleys and thus modulates the orbital motion of Dirac electrons. The energy dependence of this effect together with the exchange splitting can be utilized to design a strain-tunable spin filter. © 2011 American Institute of Physics.

Guo L.,Dalian University of Technology | Lin G.-H.,Dalian University of Technology | Ye J.J.,University of Victoria
SIAM Journal on Optimization | Year: 2012

This paper studies stability for parametric mathematical programs with geometric constraints. We show that, under the no nonzero abnormal multiplier constraint qualification and the second-order growth condition or second-order sufficient condition, the locally optimal solution mapping and stationary point mapping are nonempty-valued and continuous with respect to the perturbation parameter and, under some suitable conditions, the stationary pair mapping is calm. Furthermore, we apply the above results to parametric mathematical programs with equilibrium constraints. In particular, we show that the M-stationary pair mapping is calm with respect to the perturbation parameter if the M-multiplier second-order sufficient condition is satisfied, and the S-stationary pair mapping is calm if the S-multiplier second-order sufficient condition is satisfied and the bidegenerate index set is empty. © 2012 Society for Industrial and Applied Mathematics.

Liu R.,Dalian University of Technology | Cao J.,Dalian University of Technology | Lin Z.,Peking University | Shan S.,Chinese Academy of Sciences
Proceedings of the IEEE Computer Society Conference on Computer Vision and Pattern Recognition | Year: 2014

Partial Differential Equations (PDEs) have been successful in solving many low-level vision tasks. However, it is a challenging task to directly utilize PDEs for visual saliency detection due to the difficulty in incorporating human perception and high-level priors to a PDE system. Instead of designing PDEs with fixed formulation and boundary condition, this paper proposes a novel framework for adaptively learning a PDE system from an image for visual saliency detection. We assume that the saliency of image elements can be carried out from the relevances to the saliency seeds (i.e., the most representative salient elements). In this view, a general Linear Elliptic System with Dirichlet boundary (LESD) is introduced to model the diffusion from seeds to other relevant points. For a given image, we first learn a guidance map to fuse human prior knowledge to the diffusion system. Then by optimizing a discrete submodular function constrained with this LESD and a uniform matroid, the saliency seeds (i.e., boundary conditions) can be learnt for this image, thus achieving an optimal PDE system to model the evolution of visual saliency. Experimental results on various challenging image sets show the superiority of our proposed learning-based PDEs for visual saliency detection. © 2014 IEEE.

Liu F.-C.,Dalian University of Technology | Simon D.F.,University of Oregon | Sun Y.-T.,Dalian University of Technology | Cao C.,University of Nottingham
Research Policy | Year: 2011

China has transformed itself from a planning to a market-oriented economy over the past three decades and has sustained a fairly long period of rapid economic growth, to which the contributions from innovation in science and technology (S&T) have become increasingly important. Then, how have China's innovation policies evolved to reflect the changing and supposedly better understanding of innovation by China's policy makers? The paper tries to answer this question through a quantitative analysis of 287 policies issued by China's central government agencies between 1980 and 2005 and of 79 policies introduced between 2006 and 2008 to implement the Medium- and Long-Term Plan for the Development of Science and Technology (2006-2020). China has shifted its S&T and industrial policy-centered innovation strategy and has pursued a series of better coordinated, innovation-oriented economic and technology initiatives that give greater attention to a portfolio of policies that include critical financial, tax, and fiscal measures. There has been a gradual departure from the pattern in which innovation policies are formulated by one single government agency, therefore steering China to a different and probably more promising innovation trajectory. © 2011 Elsevier B.V. All rights reserved.

Chu S.,University of California at Riverside | Wang G.,University of California at Riverside | Zhou W.,Fudan University | Lin Y.,University of Central Florida | And 7 more authors.
Nature Nanotechnology | Year: 2011

Ultraviolet semiconductor lasers are widely used for applications in photonics, information storage, biology and medical therapeutics. Although the performance of gallium nitride ultraviolet lasers has improved significantly over the past decade, demand for lower costs, higher powers and shorter wavelengths has motivated interest in zinc oxide (ZnO), which has a wide direct bandgap and a large exciton binding energy. ZnO-based random lasing has been demonstrated with both optical and electrical pumping, but random lasers suffer from reduced output powers, unstable emission spectra and beam divergence. Here, we demonstrate electrically pumped Fabry-Perot type waveguide lasing from laser diodes that consist of Sb-doped p-type ZnO nanowires and n-type ZnO thin films. The diodes exhibit highly stable lasing at room temperature, and can be modelled with finite-difference time-domain methods. © 2011 Macmillan Publishers Limited. All rights reserved.

Agency: European Commission | Branch: FP7 | Program: CP | Phase: ENERGY.2009.5.2.2 | Award Amount: 2.73M | Year: 2009

This project addresses the fundamentally important and urgent issue regarding the accurate predictions of fluid phase, discharge rate, emergency isolation and subsequent atmospheric dispersion during accidental releases from pressurised CO2 pipelines to be employed as an integral part of large scale Carbon Capture and Storage (CCS) chain. This information is pivotal to quantifying all the hazard consequences associated with CO2 pipeline failure forming the basis for emergency response planning and determining minimum safe distances to populated areas. The development of state of the art multiphase heterogeneous discharge and dispersion models for predicting the correct fluid phase during the discharge process will be of particular importance given the very different hazard profiles of CO2 in the gas and solid states. Model validations will be based on both small scale controlled laboratory conditions as well as large scale field trials using a unique CCS facility in China. A cost/benefit analysis will be performed to determine the optimum level of impurities in the captured CO2 stream based on safety and economic considerations. The work proposed, carried out over a period of 36 months will embody the understanding gained within safety and risk assessment tools that can be used for evaluating the adequacy of controls in CO2 pipelines, with best practice guidelines also being developed. The proposal addresses the main themes of the Collaborative Call in that it has a predominant research component and its successful outcome would allow the safe and commercial deployment of large scale near zero emission power generation technology based on CCS. The project also enjoys strategic leadership from members the Carbon Sequestration Leadership Forum and highly relevant collaboration with the worlds second largest and fastest producer of CO2, China.

Li J.,State Key Laboratary of Fine Chemicals | Li Q.,Dalian University of Technology | Liu D.,Dalian University of Technology
ACS Applied Materials and Interfaces | Year: 2011

A series of novel red-emitting thieno-[3,4-b]-pyrazine-cored molecules containing oligo-carbazole dendrons (called C1-TP, C2-TP) are synthesized. Their photophysical, electrochemical, and electroluminescent properties are investigated. The peripheral carbazolyl units facilitate the hole transporting ability and inhibit the intermolecular interactions, but quench the fluorescence of the thieno-[3,4-b]-pyrazine core through Intramolecular Charge Transfer (ICT). Introduction of a polyphenyl spacer between the core and the first generation carbazole dendrons, i.e., C-DTP, decreases the ICT efficiency. In addition to providing the site-isolation effect on the planar emissive core, these bulky dendrons enable these molecules to be solution processable. As a result, efficient OLEDs with saturated red emission are fabricated by spin coating technique using these dendritic materials as nondoped emitting layer. C-DTP exhibits much better device performance than C1-TP and C2-TP, while the small molecular reference compound containing neither the spacer nor the carbazole dendrons (TP) fails to transmit pure red emission under identical conditions. A brightness of 925 cd m-2 and a luminous efficiency of 0.53 cd A-1 are obtained for C-DTP, which are comparable with OLEDs fabricated from thieno-[3,4-b]-pyrazine-based counterparts by the vacuum deposition method or those assembled with other red fluorescent dendrimers via the solution processing method. © 2011 American Chemical Society.

Xu D.-M.,Henan Institute of Engineering | Qiu L.,North China University of Water Conservancy and Electric Power | Chen S.,Dalian University of Technology
Journal of Hydrologic Engineering | Year: 2012

The accurate estimation of Muskingum model parameter is essential to give flood routing for flood control in water resources management. The Muskingum model continues to be a popular method for flood routing, and its parameter estimation is a global optimization problem with the main objective to find a set of optimal model parameter values that attains a best fit between observed and computed flow. Although some techniques have been employed to estimate the parameters for Muskingum model, an efficient method for parameter estimation in Muskingum model is still required to improve the computational precision. Therefore, in this paper, the differential evolution (DE) algorithm is studied for estimation of Muskingum model parameter. A case study with actual data from previous literature, the experimental results showed an excellent performance in its optimization result and performance analysis and demonstrates that DE is an alternative technique to estimate the parameters of the Muskingum model. © 2012 American Society of Civil Engineers.

Wang M.,Dalian University of Technology | Sun L.,Dalian University of Technology | Sun L.,KTH Royal Institute of Technology
ChemSusChem | Year: 2010

Photocatalytic hydrogen production by noble-metal-free molecular catalysts and related nanomaterials is discussed in this Highlight. Several recent nanomaterials, incorporating Fe- and Ni-based molecular catalysts, are highly effective for photo- and electrochemical hydrogen production, with good stabilities. © 2010 Wiley-VCH Verlag GmbH& Co. KGaA, Weinheim.

Wang M.,Dalian University of Technology | Chen L.,Dalian University of Technology | Sun L.,Dalian University of Technology | Sun L.,KTH Royal Institute of Technology
Energy and Environmental Science | Year: 2012

This perspective article reviews the recent important progress in electrocatalytic hydrogen production catalyzed by earth-abundant metal complexes. The catalysts are divided into two categories depending on the media used in the hydrogen-evolving reactions, with an emphasis on the types of acids employed. The catalysts used in the first category, which work in organic solutions, include nickel and cobalt complexes with base-containing diphosphine ligands, cobaloximes, cobalt tetrapyridine complexs, and [NiFe]- and [FeFe]-hydrogenase mimics. Molybdenum and cobalt pentapyridine complexes, as well as the cobalt bis(iminopyridine) complex reported very recently, are the most important examples of catalysts used in the second category, which work in aqueous solutions. The advantages and disadvantages of the different types of catalysts are discussed and the hydrogen-evolving mechanisms for the well-studied catalysts are illustrated. In addition, several molecular catalyst-modified electrodes for hydrogen production are described. © 2012 The Royal Society of Chemistry.

Pacheco-Torgal F.,University of Minho | Ding Y.,Dalian University of Technology | Jalali S.,University of Minho
Construction and Building Materials | Year: 2012

The volume of polymeric wastes like tyre rubber and polyethylene terephthalate bottles (PET) is increasing at a fast rate. An estimated 1000 million tyres reach the end of their useful lives every year and 5000 millions more are expected to be discarded in a regular basis by the year 2030. Up to now a small part is recycled and millions of tyres are just stockpiled, landfilled or buried. As for PET bottles annual consumption represent more than 300,000 million units. The majority is just landfilled. This paper reviews research published on the performance of concrete containing tyre rubber and PET wastes. Furthermore it discusses the effect of waste treatments, the size of waste particles and the waste replacement volume on the fresh and hardened properties of concrete. © 2011 Elsevier Ltd. All rights reserved.

Li F.,Dalian University of Technology | Jiang Y.,Dalian University of Technology | Zhang B.,Dalian University of Technology | Huang F.,Dalian University of Technology | And 3 more authors.
Angewandte Chemie - International Edition | Year: 2012

Time to split: Supramolecular assemblies containing both photosensitizers and a ruthenium water-oxidation catalyst were prepared and characterized. The pictured assembly exhibits, for the first time, enhanced visible-light-driven water oxidation activity. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Piao Y.,Dalian University of Technology | Zhang M.,Keimyung University | Shin D.,Dongseo University | Yoo H.,Sangmyung University
Optics Letters | Year: 2013

This Letter presents an off-axially distributed image sensing (ODIS) system for three-dimensional (3D) imaging and visualization. The off-axially distributed sensing method provides both lateral and longitudinal perspectives for 3D scenes even though the sensor moves along a slanted, one-dimensional path. A 3D volume is generated from a set of recorded images by use of a computational algorithm based on ray backprojection. Preliminary experimental results are presented to illustrate the feasibility of the proposed system. To the best of our knowledge, this is the first report on 3D imaging and visualization using ODIS. © 2013 Optical Society of America.

Chen L.,Dalian University of Technology | Wang M.,Dalian University of Technology | Han K.,Dalian University of Technology | Zhang P.,Dalian University of Technology | And 3 more authors.
Energy and Environmental Science | Year: 2014

Self-assembled molecular iron and cobalt catalysts (MP4N 2, M = Fe, Co) bearing a multihydroxy-functionalized tetraphosphine ligand electrocatalyze H2 generation from neutral water on a mercury electrode at -1.03 and -0.50 V vs. NHE, respectively. Complex CoP 4N2 displays extremely low overpotential (E onset = 80 mV) while maintaining high activity and good stability. Bulk electrolysis of CoP4N2 in a neutral phosphate buffer solution at -1.0 V vs. NHE produced 9.24 × 104 mol H 2 per mol cat. over 20 h, with a Faradaic efficiency close to 100% and without apparent deactivation. This journal is © 2014 The Royal Society of Chemistry.

Zhao N.,Dalian University of Technology | Yu F.R.,Carleton University | Leung V.C.M.,University of British Columbia
IEEE Wireless Communications | Year: 2015

IA is a promising technology for interference management in wireless networks. However, there are still some practical challenges. Signal to interference plus noise ratio (SINR) decrease is one of the key challenging issues due to the inherent property of IA and channel fading. Recent advances in OC, including multiuser diversity and antenna selection, can be applied in IA wireless networks to improve the SINR performance. In this article we review some existing research work on OC-based IA wireless networks. In addition, we propose a novel simultaneous wireless information and power transfer scheme based on OC in IA wireless networks. Simulation results are presented to show the performance comparison of these schemes. The methods to reduce the complexity of the OC-based IA algorithms are finally summarized. © 2002-2012 IEEE.

Wang M.,Dalian University of Technology | Han K.,Dalian University of Technology | Zhang S.,Dalian University of Technology | Sun L.,Dalian University of Technology | Sun L.,KTH Royal Institute of Technology
Coordination Chemistry Reviews | Year: 2015

The development of energy-efficient, cost-effective and durable photocatalytic systems for water splitting is one of the scientific problems that must be solved before the successful transformation from a fossil fuel-based economy to a solar fuel-based economy can be realized. Conventional photocatalytic systems are generally divided into heterogeneous systems of semiconductors, usually modified by noble metals or inorganic cocatalysts, and homogeneous systems comprised of molecular catalysts and organic or organometallic chromophores. In recent years, some hybrid photocatalytic systems were reported to be highly active and robust for photoinduced H2 production, indicating that the integration of semiconducting materials with proper molecular catalysts is an effective strategy for constructing efficient photocatalytic systems for water splitting. This review will focus on hybrid photocatalytic systems, developed in the past three years, in which proton reduction molecular catalysts incorporate either semiconducting materials or inorganic, metal-organic, and other polymeric nanomaterials for photochemical H2 generation from water. In the last section of the review, problems existing in the current hybrid photocatalytic systems are discussed; future challenges and developments are envisaged. © 2014 Elsevier B.V.

Yu Z.,Dalian University of Technology | Li F.,Dalian University of Technology | Sun L.,Dalian University of Technology | Sun L.,KTH Royal Institute of Technology
Energy and Environmental Science | Year: 2015

Conceptually new research on dye-sensitized photoelectrochemical cells (DS-PECs), through which solar-driven water splitting to generate solar fuel in the form of hydrogen is realized, has attracted growing interest in the past few years. DS-PECs are based on the configurations of dye-sensitized solar cells (DSCs), but with an aim to drive the two half reactions of water splitting at physically separated two compartments (electrodes) rather than to generate electrical power. Herein, we review some of the recent advances in the design and construction of functional DS-PECs for visible light-driven water splitting together with some comments on the performance of these devices. Future challenges towards the development of more efficient dye-sensitized photoelectrochemical devices are addressed in the end. © 2015 The Royal Society of Chemistry.

Cheng M.,Dalian University of Technology | Yang X.,Dalian University of Technology | Li S.,Dalian University of Technology | Wang X.,Dalian University of Technology | And 2 more authors.
Energy and Environmental Science | Year: 2012

A new iodine-free electrolyte based on amino acids L-cysteine/L-cystine as a redox couple has been designed and synthesized. DSSCs fabricated with the conventional I -/I 3 - redox couple gave efficiencies of 8.1% and 6.3% under optimized experimental conditions based on ruthenium dye, N719, and metal-free organic dye, TH202, respectively. Based on the same dyes, the DSSCs employing the new L-cysteine/L-cystine redox couple showed comparable efficiencies of 7.7% and 5.6%, respectively. However, higher incident-photon-to-electron (IPCE) conversion efficiencies and larger J sc values were found for devices with the L-cysteine/L-cystine redox couple than with I -/I 3 -. From an electrochemical impedance spectroscopic study, we found that the charge recombination between the conduction band electrons in the TiO 2 film and the electrolyte containing the L-cysteine/L-cystine redox couple is restrained. This journal is © 2012 The Royal Society of Chemistry.

Duan L.,KTH Royal Institute of Technology | Tong L.,KTH Royal Institute of Technology | Xu Y.,KTH Royal Institute of Technology | Sun L.,KTH Royal Institute of Technology | Sun L.,Dalian University of Technology
Energy and Environmental Science | Year: 2011

This perspective article reports the most significant advances in the field of water oxidation - from molecular water oxidation catalysts (WOCs) to photoelectrochemical cells. Different series of catalysts that can be applied in visible light-driven water oxidation catalysis are discussed in details and several key aspects of their catalytic mechanisms are introduced. In order to construct a water oxidation electrode from molecular catalysts, proper immobilization methods have to be employed. Herein, we present one section about how to attach catalysts onto an electrode/material surface. Finally, the state of the art photoelectrochemical cells that achieve visible light-driven water splitting are described. © 2011 The Royal Society of Chemistry.

Tong L.,KTH Royal Institute of Technology | Duan L.,KTH Royal Institute of Technology | Xu Y.,Dalian University of Technology | Privalov T.,University of Stockholm | Sun L.,KTH Royal Institute of Technology
Angewandte Chemie - International Edition | Year: 2011

Small change, big difference: A minor structural modification of water-oxidation catalysts changes the kinetics of O2 evolution from second- to first-order (see scheme). According to DFT calculations, the torsional flexibility of the chelating ligands and their reorganization through the catalytic cycle are implicated in pathway selectivity, and the auxiliary carboxylate group becomes involved in proton-coupled nucleophilic attack. © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Liu C.-G.,Dalian University of Technology | Xue C.,Dalian University of Technology | Lin Y.-H.,University of Saskatchewan | Bai F.-W.,Dalian University of Technology | Bai F.-W.,Shanghai JiaoTong University
Biotechnology Advances | Year: 2013

Many fermentation products are produced under microaerobic or anaerobic conditions, in which oxygen is undetectable by dissolved oxygen probe, presenting a challenge for process monitoring and control. Extracellular redox potentials that can be detected conveniently affect intracellular redox homeostasis and metabolism, and consequently control profiles of fermentation products, which provide an alternative for monitoring and control of these fermentation processes. This article reviews updated progress in the impact of redox potentials on gene expression, protein biosynthesis and metabolism as well as redox potential control strategies for more efficient production of fermentation products, taking ethanol fermentation by the yeast Saccharomyces under microaerobic conditions and butanol production by the bacterium Clostridium under anaerobic conditions as examples. © 2012 Elsevier Inc.

Pacheco-Torgal F.,University of Minho | Miraldo S.,University of Aveiro | Ding Y.,Dalian University of Technology | Labrincha J.A.,University of Aveiro
Construction and Building Materials | Year: 2013

According to the 2011 ERMCO statistics only a mere 11% of the ready-mixed concrete class production relates to the HPC target, furthermore, this percentage remains unchanged at least since the year 2001. This represents a strange option from the construction industry since HPC offers several advantages over normal-strength concrete, namely, high strength and high durability. Therefore, HPC allows for concrete structures with less steel reinforcement and a longer service life, both of which are crucial issues in the eco-efficiency of construction materials. Although nanotechnology is a very hot issue the fact is that investigations on the field of concrete with nanoparticles are rare (100 in 10,000 Scopus concrete related articles published in the last decade). Actually, it remains to be seen how this research area will contribute to concrete eco-efficiency. This paper summarizes current knowledge on the field of concrete containing nanoparticles. It includes the influence of nanoparticles on the mechanical properties of concrete and on its durability. It also includes calcium leaching control. Moreover, the problem of efficient dispersion of nanoparticles is analyzed. © 2012 Elsevier Ltd. All rights reserved.

Gao Y.,Dalian University of Technology | Ding X.,Dalian University of Technology | Liu J.,Dalian University of Technology | Wang L.,KTH Royal Institute of Technology | And 4 more authors.
Journal of the American Chemical Society | Year: 2013

A molecular water oxidation catalyst (2) has been synthesized and immobilized together with a molecular photosensitizer (1) on nanostructured TiO2 particles on FTO conducting glass, forming a photoactive anode (TiO2(1+2)). By using the TiO2(1+2) as working electrode in a three-electrode photoelectrochemical cell (PEC), visible light driven water splitting has been successfully demonstrated in a phosphate buffer solution (pH 6.8), with oxygen and hydrogen bubbles evolved respectively from the working electrode and counter electrode. By applying 0.2 V external bias vs NHE, a high photocurrent density of more than 1.7 mA·cm-2 has been achieved. This value is higher than any PEC devices with molecular components reported in literature. © 2013 American Chemical Society.

Xue C.,Dalian University of Technology | Zhao X.-Q.,Dalian University of Technology | Liu C.-G.,Dalian University of Technology | Chen L.-J.,Dalian University of Technology | And 2 more authors.
Biotechnology Advances | Year: 2013

Butanol has been acknowledged as an advanced biofuel, but its production through acetone-butanol-ethanol (ABE) fermentation by clostridia is still not economically competitive, due to low butanol yield and titer. In this article, update progress in butanol production is reviewed. Low price and sustainable feedstocks such as lignocellulosic residues and dedicated energy crops are needed for butanol production at large scale to save feedstock cost, but processes are more complicated, compared to those established for ABE fermentation from sugar- and starch-based feedstocks. While rational designs targeting individual genes, enzymes or pathways are effective for improving butanol yield, global and systems strategies are more reasonable for engineering strains with stress tolerance controlled by multigenes. Compared to solvent-producing clostridia, engineering heterologous species such as Escherichia coli and Saccharomyces cerevisiae with butanol pathway might be a solution for eliminating the formation of major byproducts acetone and ethanol so that butanol yield can be improved significantly. Although batch fermentation has been practiced for butanol production in industry, continuous operation is more productive for large scale production of butanol as a biofuel, but a single chemostat bioreactor cannot achieve this goal for the biphasic ABE fermentation, and tanks-in-series systems should be optimized for alternative feedstocks and new strains. Moreover, energy saving is limited for the distillation system, even total solvents in the fermentation broth are increased significantly, since solvents are distilled to ~. 40% by the beer stripper, and more than 95% water is removed with the stillage without phase change, even with conventional distillation systems, needless to say that advanced chemical engineering technologies can distil solvents up to ~. 90% with the beer stripper, and the multistage pressure columns can well balance energy consumption for solvent fraction. Indeed, an increase in butanol titer with ABE fermentation can significantly save energy consumption for medium sterilization and stillage treatment, since concentrated medium can be used, and consequently total mass flow with production systems can be reduced. As for various in situ butanol removal technologies, their energy efficiency, capital investment and contamination risk to the fermentation process need to be evaluated carefully. © 2013 Elsevier Inc.

Duan L.,KTH Royal Institute of Technology | Bozoglian F.,Institute of Chemical Research of Catalonia | Mandal S.,Institute of Chemical Research of Catalonia | Stewart B.,University of Stockholm | And 5 more authors.
Nature Chemistry | Year: 2012

Across chemical disciplines, an interest in developing artificial water splitting to O 2 and H 2, driven by sunlight, has been motivated by the need for practical and environmentally friendly power generation without the consumption of fossil fuels. The central issue in light-driven water splitting is the efficiency of the water oxidation, which in the best-known catalysts falls short of the desired level by approximately two orders of magnitude. Here, we show that it is possible to close that 'two orders of magnitude' gap with a rationally designed molecular catalyst [Ru(bda)(isoq) 2] (H 2 bda = 2,2'-bipyridine-6,6'- dicarboxylic acid; isoq = isoquinoline). This speeds up the water oxidation to an unprecedentedly high reaction rate with a turnover frequency of >300 s -1. This value is, for the first time, moderately comparable with the reaction rate of 100-400s -1 of the oxygen-evolving complex of photosystem II in vivo. © 2012 Macmillan Publishers Limited. All rights reserved.

Tian H.,KTH Royal Institute of Technology | Sun L.,KTH Royal Institute of Technology | Sun L.,Dalian University of Technology
Journal of Materials Chemistry | Year: 2011

Redox couples, as one of the crucial components of dye-sensitized solar cells, have been investigated for many years. Due to the many drawbacks of I-/I3 - electrolyte, scientists have paid more attention to seeking other alternative electrolyte systems. Up to now, the best efficiency of iodine-free redox couple-based DSCs, 7.5%, has been achieved by ferrocene/ferrocenium redox couple under AM 1.5G, 100 mW cm-2 light illumination and other redox couples also show the promising future in DSCs. In this feature article, we systematically present three series of iodine-free redox couples including metal-complexes, inorganic and pure organic redox couples, and further compare the different photovoltaic and photophysical properties of these redox couples. As a consequence, the goals of this article are to show the important progress achieved in the redox couples research area of DSCs and analyze the advantages as well as the disadvantages of these redox couples to speed up the further development of iodine-free redox couples in the future. © 2011 The Royal Society of Chemistry.

Yu Z.,Dalian University of Technology | Sun L.,Dalian University of Technology | Sun L.,KTH Royal Institute of Technology
Advanced Energy Materials | Year: 2015

In less than three years, the photovoltaic community has witnessed a rapid emergence of a new class of solid-state heterojunction solar cells based on solution-processable organometal halide perovskite absorbers. The energy conversion efficiency of solid-state perovskite solar cells (PSCs) has been quickly increased to a certified value of 20.1% by the end of 2014 because of their unique characteristics, such as a broad spectral absorption range, large absorption coefficient, high charge carrier mobility and diffusion length. Here, the focus is specifically on recent developments of hole-transporting materials (HTMs) in PSCs, which are essential components for achieving high solar cell efficiencies. Some fundamentals with regard to PSCs are first presented, including the history of PSCs, device architectures and general operational principles of PSCs as well as various techniques developed for the fabrications of uniform and dense perovskite complexes. A broad range of the state-of-the-art HTMs being used in PSCs are then discussed in detail. Finally, an outlook on the design of more efficient HTMs for highly efficient PSCs is addressed. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Ding Y.,Dalian University of Technology | You Z.,Hebei Polytechnic University | Jalali S.,University of Minho
Engineering Structures | Year: 2011

Based on the investigation of the influence of steel fibre on the workability of fresh self-consolidating concrete (SCC), this paper presents the experimental results carried out on a series of simply supported SCC rectangular beams, using steel fiber reinforcement with and without stirrups, and subjected to four-point symmetrically placed vertical loads. The major test variables are the steel fibre content and stirrup ratios. The current study on the shear strength of conventional reinforced concrete (RC) beams verifies the shear strength of SCC beams with steel fibres. The investigation indicates that the shear strength significantly increases by increasing the fibre content; the addition of steel fibres in an adequate percentage can change the failure mode from a brittle shear collapse into a ductile flexural mechanism. The stirrups can be partially replaced by steel fibres. The combination of steel fibres and stirrups demonstrates a positive composite effect on the mechanical behaviour. The shear strength recorded experimentally is compared with the value obtained from the proposed formula, and the correlation is satisfactory. © 2010 Elsevier Ltd.

Tong L.,KTH Royal Institute of Technology | Gothelid M.,KTH Royal Institute of Technology | Sun L.,KTH Royal Institute of Technology | Sun L.,Dalian University of Technology
Chemical Communications | Year: 2012

A molecular Ru(ii) water oxidation catalyst was immobilized on a conductive carbon surface through a covalent bond, and its activity was maintained at the same time. The method can be applied to other materials and may inspire development of artificial photosynthesis devices. This journal is © The Royal Society of Chemistry 2012.

Hagfeldt A.,Uppsala University | Hagfeldt A.,KTH Royal Institute of Technology | Hagfeldt A.,Dalian University of Technology | Boschloo G.,Uppsala University | And 4 more authors.
Chemical Reviews | Year: 2010

Dye-sensitized solar cells (DSCs) offer the possibilities to design solar cells with a large flexibility in shape, color, and transparency. DSC research groups have been established around the world with biggest activities in Europe, Japan, Korea, China, and Australia. The sun emits light with a range of wavelengths from the ultraviolet and visible to the infrared. It peaks in the visible, resembling the spectrum of a blackbody at a temperature of 5760 K. It is, however, influenced by atmospheric absorption and the position of the sun. The advent of heteroleptic ruthenium complexes furnished with an antenna function has taken the performance of the DSC to a new level. Two examples of these dyes are Z991 and C101. Compared with the classical DSC Ru dyes, their extinction coefficients are higher and the spectral response is shifted to the red. The positions of the energy levels at the oxide/dye/electrolyte interface are fundamentally important to the function of the DSC.

Wang W.-H.,Dalian University of Technology | Himeda Y.,Japan National Institute of Advanced Industrial Science and Technology | Himeda Y.,Japan Science and Technology Agency | Muckerman J.T.,Brookhaven National Laboratory | And 2 more authors.
Chemical Reviews | Year: 2015

A study was conducted to show CO2 hydrogenation as an alternative method for so-called artificial photosynthesis to produce fuels, such as formate/formic acid and methanol, with good selectivity and high efficiency. For CO2 hydrogenation, an inexpensive and green source of H2 is needed in contrast to the industrial reforming of natural gas. To obtain formic acid for the regeneration of H2 or use in fuel cells, additional acid must be added to neutralize the formate. As an alternative to the use of a base in CO2 hydrogenation, a Lewis acid is a useful additive for H2 release from formic acid. To reduce the cost, catalysis with earth-abundant metals such as Fe or Co is highly desirable, and considerable progress has been achieved. Innovative ligands with functional groups are capable of gaining or losing one or more protons, and photoresponsive ligands capable of undergoing a useful change in properties upon irradiation. Kinetic isotope effects and computational studies provide clear evidence for the involvement of a water molecule in the rate-determining heterolysis of H2 in CO2 hydrogenation that accelerates proton transfer through the formation of a water bridge. Solution pH alters the rate-determining step for H2 generation from formic acid with these bioinspired complexes.

Hou Y.,Dalian University of Technology | Li X.-Y.,Dalian University of Technology | Li X.-Y.,Hong Kong University of Science and Technology | Zhao Q.-D.,Dalian University of Technology | And 2 more authors.
Advanced Functional Materials | Year: 2010

An electrode with intimate and well-aligned ZnFe 2O 4/TiO 2 composite nanotube arrays is prepared via electrochemical anodization of pure titanium foil in fluorine-containing ethylene glycol, followed by a novel cathodic electrodeposition method. The deposition of ZnFe 2O 4 is promoted in the selfaligned, vertically oriented TiO 2 nanotube arrays but minimized at the tube entrances. Thus, pore clogging is prevented. Environmental scanning electron microscopy, energy-dispersive X-ray spectra, high-resolution transmission electron microscopy, X-ray diffraction patterns, and X-ray photoelectron spectroscopy indicate that the as-prepared samples are highly ordered and vertically aligned TiO 2 nanotube arrays with ZnFe 2O 4 nanoparticles loading. The TiO 2 nanotubes are anatase with the preferential orientation of <101> plane. Enhanced absorption in both UVand visible light regions is observed for the composite nanotube arrays. The current-voltage curve of ZnFe 2O 4-loaded TiO 2 nanotube arrays reveals a rectifying behavior. The enhanced separation of photoinduced electrons and holes is demonstrated by surface photovoltage and photocurrent measurements. Meanwhile, the photoelectrochemical investigations verify that the ZnFe 2O 4/TiO 2 composite nanotube array modified electrode has a more effective photoconversion capability than the aligned TiO 2 nanotube arrays alone. In addition, the photoelectrocatalytic ability of the novel electrode is found enhanced in the degradation of 4-chlorophenol. © 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Han Y.-C.,University of Aarhus | Han Y.-C.,Dalian University of Technology | Madsen L.B.,University of Aarhus
Physical Review A - Atomic, Molecular, and Optical Physics | Year: 2013

The interference minimum in the high-order harmonic spectrum of H 2+ is studied by solving the full three-dimensional time-dependent Schrödinger equation for the electronic motion keeping the nuclei fixed. The two-center interference model works well when the internuclear distance is around its equilibrium value where also recombination to the 2Σg+ (1sσg) ground state dominates. As the internuclear distance is increased, the minimum first shifts in position compared with the prediction of the two-center interference model and subsequently disappears. These effects are caused by the excited 2Σu+ (2pσu) state, partly due to the interference between the amplitudes of recombination to the ground and excited states, but also partly due to the signal associated with recombination to the excited state alone. We find that at internuclear distances beyond Râ‰3 a.u. the signal close to the harmonic cutoff may be completely dominated by recombination into the excited 2Σu+ (2pσu) state. © 2013 American Physical Society.

Tang Z.,Dalian University of Technology | Liu S.,Dalian University of Technology | Zhang Z.,Dalian University of Technology | Zhang Z.,Shanghai Institute of Satellite Engineering
Thin-Walled Structures | Year: 2013

A type of cylindrical multi-cell column is proposed to improve energy absorption performance, which is inspired by the phenomenon that the circular tube is more efficient than the square tube in energy absorption. This type of structure shows high performance in energy absorption for its considerable number of corners on the cross section and the angles between neighbor flanges are in the optimal range as well as some more efficient cylindrical shells have been adopted. Numerical examples illustrate that cylindrical multi-cell column is more efficient than square column and square multi-cell column in energy absorption. In addition, a parametric study considering the effects of geometrical parameters on the structural crashworthiness has been carried out. And it is found that wall thickness, the number of cells alone the radial and circumferential directions have a distinct effect on the energy absorption. © 2012 Elsevier Ltd. All rights reserved.

Song B.,CAS Shanghai Institute of Applied Physics | Yang J.,Sichuan University | Zhao J.,Dalian University of Technology | Fang H.,CAS Shanghai Institute of Applied Physics
Energy and Environmental Science | Year: 2011

The intercalation and diffusion of lithium ions in a bundle of carbon nanotubes (CNTs) are investigated via an ab initio molecular dynamics simulation method based on the density functional theory. We found that lithium ions quickly penetrate into the CNTs and the space between neighboring CNTs. With a low Li ion density, the Li ions tend to stay close to the nanotube ends. Interestingly, Li ions are able to penetrate through the carbon nanotube and move from one end to the other. We also discovered that Li ions may remain between two neighboring CNTs, which presents a new approach for Li ion intercalation and storage. Importantly, Li ions located among three neighboring CNTs have very strong adsorption potentials that are a factor of four larger than those of Li ions located along the central axis of a single-walled nanotube (SWNT). This indicates that Li ions located among three neighboring CNTs would be very difficult to remove from a nanotube bundle, which suggests that Li storage capacity in this case is possibly irreversible, and that keeping the nanotubes apart with an appropriate distance would hinder or promote the formation of irreversible intercalation. Our findings contribute to the understanding of lithium intercalation and diffusion in CNTs, which has implications for the experimental development and application of rechargeable Li ion batteries. © 2011 The Royal Society of Chemistry.

Li M.,Newcastle University | Li M.,Dalian University of Technology | Scott K.,Newcastle University
Electrochimica Acta | Year: 2010

Poly(tetrafluoroethylene) PTFE/PBI composite membranes doped with H3PO4 were fabricated to improve the performance of high temperature polymer electrolyte membrane fuel cells (HT-PEMFC). The composite membranes were fabricated by immobilising polybenzimidazole (PBI) solution into a hydrophobic porous PTFE membrane. The mechanical strength of the membrane was good exhibiting a maximum load of 35.19 MPa. After doping with the phosphoric acid, the composite membrane had a larger proton conductivity than that of PBI doped with phosphoric acid. The PTFE/PBI membrane conductivity was greater than 0.3 S cm-1 at a relative humidity 8.4% and temperature of 180 °C with a 300% H3PO4 doping level. Use of the membrane in a fuel cell with oxygen, at 1 bar overpressure gave a peak power density of 1.2 W cm-2 at cell voltages >0.4 V and current densities of 3.0 A cm-2. The PTFE/PBI/H3PO4 composite membrane did not exhibit significant degradation after 50 h of intermittent operation at 150 °C. These results indicate that the composite membrane is a promising material for vehicles driven by high temperature PEMFCs. © 2009 Elsevier Ltd.

Hong L.J.,Hong Kong University of Science and Technology | Yang Y.,University of California at Irvine | Zhang L.,Dalian University of Technology
Operations Research | Year: 2011

When there is parameter uncertainty in the constraints of a convex optimization problem, it is natural to formulate the problem as a joint chance constrained program (JCCP), which requires that all constraints be satisfied simultaneously with a given large probability. In this paper, we propose to solve the JCCP by a sequence of convex approximations. We show that the solutions of the sequence of approximations converge to a Karush-Kuhn-Tucker (KKT) point of the JCCP under a certain asymptotic regime. Furthermore, we propose to use a gradient-based Monte Carlo method to solve the sequence of convex approximations. © 2011 INFORMS.

Teng W.,Dalian University of Technology | Li X.,Dalian University of Technology | Li X.,Hong Kong University of Science and Technology | Zhao Q.,Dalian University of Technology | Chen G.,Hong Kong University of Science and Technology
Journal of Materials Chemistry A | Year: 2013

TiO2 nanotube arrays were decorated with Ag/Ag 3PO4 nanoparticles through a sequential chemical bath deposition and followed by partial reduction of Ag+ ions in the Ag3PO4 nanoparticles to Ag0 under UV irradiation. The structure and optical properties of the Ag/Ag 3PO4/TiO2 nanotube electrode were characterized by scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HRTEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), UV-Vis diffuse reflectance spectroscopy, photoluminescence (PL) spectroscopy and electrochemical techniques. The photoelectrocatalytic (PEC) activity of the composite electrode was evaluated by the decomposition of 2-chlorophenol under visible light irradiation (λ > 420 nm). Clusters of Ag/Ag3PO4 nanoparticles were successfully formed on the surface of the TiO2 nanotubes (NTs) causing no damage to the ordered structure of the nanotubes. The PL intensity of Ag/Ag3PO 4/TiO2 NTs was much lower than that of TiO2 nanotubes. The p-type Ag3PO4 and Ag nanoparticles deposited on the TiO2 NTs could promote the transfer of photo-generated electrons, which inhibited the recombination of electrons and holes effectively, leading to a significant increase in the photocurrent density. Moreover, the Ag/Ag3PO4/TiO2 heterostructure photoelectrodes showed much higher PEC activity than the pure TiO2 NTs for the degradation of 2-CP aqueous solution under visible light irradiation. The enhanced PEC activity could be attributed to the visible-light photocatalytic activity of Ag3PO4 and the heterostructure between Ag3PO4 and TiO2. The electron spin resonance (ESR) spin-trap study further demonstrated that OH could be generated on the Ag/Ag3PO4/TiO2 NTs under visible light irradiation. © 2013 The Royal Society of Chemistry.

Huang L.,Dalian University of Technology | Cheng S.,Zhejiang University | Chen G.,Hong Kong University of Science and Technology
Journal of Chemical Technology and Biotechnology | Year: 2011

Recalcitrant wastes including dyes, pesticides, explosives, heavy metals, polyalcohols, furan derivatives and phenolic substances, are of special concern owing to their recalcitrance and persistence in the environment. Bioelectrochemical systems (BESs) including microbial fuel cells (MFCs) and microbial electrolysis cells (MECs), integrate three important wastewater treatment options, namely, biological treatment, electrolytic dissociation and electrochemical oxidation/reduction, and are regarded as a new sustainable and effective strategy for treatment of these wastes. The simultaneous and cooperative roles of these multiple units running in parallel in BESs contribute to the efficiency of recalcitrant waste treatment, while substrate metabolism is considered to be a key step triggering different unit operations. An up-to-date review is provided on recent research and development in BESs-based recalcitrant wastes treatment. MFCs and MECs, as two types of BESs, are summarized in terms of treatment efficiency, recalcitrant substance metabolic pathway and microorganism diversity after a brief introduction to the electrochemical process for recalcitrant waste treatment. The scientific and technical challenges that have yet to be faced in the future are also discussed. © 2010 Society of Chemical Industry.

He Z.,Dalian University of Technology | Yu W.,Hong Kong University of Science and Technology
Computational Biology and Chemistry | Year: 2010

Feature selection techniques have been used as the workhorse in biomarker discovery applications for a long time. Surprisingly, the stability of feature selection with respect to sampling variations has long been under-considered. It is only until recently that this issue has received more and more attention. In this article, we review existing stable feature selection methods for biomarker discovery using a generic hierarchical framework. We have two objectives: (1) providing an overview on this new yet fast growing topic for a convenient reference; (2) categorizing existing methods under an expandable framework for future research and development. © 2010 Elsevier Ltd.

Liang Y.,Dalian University of Technology | Liang Y.,Yili Normal University | Wang X.,Dalian University of Technology
Physica A: Statistical Mechanics and its Applications | Year: 2014

In this paper, we propose a pinning synchronization control scheme in complex networks with non-delay and delay couplings, which uses two switched periods to provide intermittent control. Criteria ensuring global exponential synchronization are obtained based on strict mathematical proofs. Meanwhile, it is shown that the delay does not depend on the control width and the non-control width. Moreover, we give a method for calculating the minimum number of pinning nodes required to achieve exponential synchronization. Finally, a numerical simulation shows the effectiveness of the pinning synchronization control scheme via an intermittent control method with two periods. © 2013 Elsevier B.V. All rights reserved.

Liu Q.,Nanjing Southeast University | Wang J.,Chinese University of Hong Kong | Wang J.,Dalian University of Technology
IEEE Transactions on Neural Networks and Learning Systems | Year: 2013

This paper presents a one-layer projection neural network for solving nonsmooth optimization problems with generalized convex objective functions and subject to linear equalities and bound constraints. The proposed neural network is designed based on two projection operators: linear equality constraints, and bound constraints. The objective function in the optimization problem can be any nonsmooth function which is not restricted to be convex but is required to be convex (pseudoconvex) on a set defined by the constraints. Compared with existing recurrent neural networks for nonsmooth optimization, the proposed model does not have any design parameter, which is more convenient for design and implementation. It is proved that the output variables of the proposed neural network are globally convergent to the optimal solutions provided that the objective function is at least pseudoconvex. Simulation results of numerical examples are discussed to demonstrate the effectiveness and characteristics of the proposed neural network. © 2013 IEEE.

Huang T.,Dalian University of Technology | Wang J.,University of Tokyo | Yu W.,Hong Kong University of Science and Technology | He Z.,Dalian University of Technology
Briefings in Bioinformatics | Year: 2012

Assembling peptides identified from tandem mass spectra into a list of proteins, referred to as protein inference, is a critical step in proteomics research. Due to the existence of degenerate peptides and 'one-hit wonders', it is very difficult to determine which proteins are present in the sample. In this paper, we review existing protein inference methods and classify them according to the source of peptide identifications and the principle of algorithms. It is hoped that the readers will gain a good understanding of the current development in this field after reading this review and come up with new protein inference algorithms. © The Author 2012. Published by Oxford University Press.

Yang K.,Nanjing Southeast University | Gao X.-W.,Dalian University of Technology
Engineering Analysis with Boundary Elements | Year: 2010

In this paper, a new boundary element analysis approach is presented for solving transient heat conduction problems based on the radial integration method. The normalized temperature is introduced to formulate integral equations, which makes the representation very simple and having no temperature gradients involved. The Green's function for the Laplace equation is adopted in deriving basic integral equations for time-dependent problems with varying heat conductivities and, as a result, domain integrals are involved in the derived integral equations. The radial integration method is employed to convert the domain integrals into equivalent boundary integrals. Based on the central finite difference technique, an implicit time marching solution scheme is developed for solving the time-dependent system of equations. Numerical examples are given to demonstrate the correctness of the presented approach. © 2010 Elsevier Ltd. All rights reserved.

Dalian University of Technology and BayGen Pharm Technology Co. | Date: 2010-10-01

Novel Fostriecin (or FST) derivatives represented by formula (I), the pharmaceutical compositions and preparation methods thereof. The pharmaceutical uses of these compounds, especially the use for the preparation of pharmaceutical compositions for treating tumor, inhibiting cell over growth, or lowering myocardial infarction and the injury to cells.

Baygen Pharm Technology Co. and Dalian University of Technology | Date: 2011-01-12

The present invention relates to a novel Fostrecin (or FST) derivatives represented by the following formula (I), the pharmaceutical compositions and preparation methods thereof, and also to the pharmaceutical uses of these compounds, especially the use of these compounds in the preparation of the pharmaceutical compositions for antitumor, inhibition of cell excessive growth, termination of cell growth, or reduction of myocardial infarction and injury to a cell.

Xu L.,Dalian University of Technology | Xu L.,CAS Institute of Theoretical Physics
Physical Review D - Particles, Fields, Gravitation and Cosmology | Year: 2015

In this paper, a specific family of f(R) models that can produce the ΛCDM background expansion history is constrained by using the currently available geometric and dynamic probes. The scale dependence of the growth rate f(z,k) in this specific family of f(R) model is shown. Therefore to eliminate the scale dependence of fσ8(z) in theory, which usually is defined as the product of f(z,k) and σ8(z), we define fσ8(z)=dσ8(z)/dlna, which is obviously scale independent and reproduces the conventional definition in the standard ΛCDM cosmology. In doing so, under the assumption that future probes having the same best fit values as the current ten data points of fσ8(z), even having 20% error bars enlarged, we find a preliminary constraint fR0=-2.58-0.58+2.14×10-6 in 1σ regions. This indicates the great potential that redshift space distortions have in constraining modified gravity theories. We also discuss the nonlinear matter power spectrum based on different halo fit models. © 2015 American Physical Society.

Xu L.,Dalian University of Technology | Xu L.,CAS Institute of Theoretical Physics
Physical Review D - Particles, Fields, Gravitation and Cosmology | Year: 2015

In a modified gravity theory, the propagation equation of gravitational waves will be presented in a nonstandard way. Therefore this tensor mode perturbation of time-space, as a complement to the scalar mode perturbation, provides a unique character distinguishing modified gravity from general relativity. To avoid the model-dependent issue, in this paper, we propose a parametrized modification to the propagation of gravitational waves. We show the effects on the angular power spectrum of cosmic microwave background radiation due to the parametrized modification and its degeneracy to the tensor mode power spectrum index nt and its running αt. Last, we report the current status on the detection of modified gravity through the currently available cosmic observations. Our results show no significant deviation to general relativity. © 2015 American Physical Society.

Yang F.,Tohoku University | Jin T.,Tohoku University | Bao M.,Dalian University of Technology | Yamamoto Y.,Tohoku University
Chemical Communications | Year: 2011

A facile, efficient, and general synthetic method for 3,4-dihalofurans has been developed via the electrophilic iodocyclization of various 4-hydroxy-2-but-2-yn-1-ones. The use of MeOH as a solvent is crucial for the efficient chemoselective synthesis of the corresponding 3,4-dihalofurans. © 2011 The Royal Society of Chemistry.

Yang F.,Tohoku University | Jin T.,Tohoku University | Bao M.,Dalian University of Technology | Yamamoto Y.,Tohoku University
Chemical Communications | Year: 2011

A facile, efficient, and general synthetic method for a wide range of 2,3-diiodinated 1,4-dihydrothiophenes and naphthalenes has been developed via the electrophilic iodocyclization of various aryl propargyl alcohols. The resulting product 2p can be used for the synthesis of a rubrene intermediate. © The Royal Society of Chemistry.

Zhao J.,Tohoku University | Asao N.,Tohoku University | Yamamoto Y.,Tohoku University | Yamamoto Y.,Dalian University of Technology | Jin T.,Tohoku University
Journal of the American Chemical Society | Year: 2014

We report a novel Pd-catalyzed alkyne-directed dual C-H activation of bis-biaryl alkynes, which produced important and useful products, 9,9-bifluorenylidene (9,9BF) derivatives, in high yields with a broad range of functional group compatibility. The combination of the PdCl2 catalyst with the MnO2 oxidant and PivOH additive is vital for realization of the present catalytic transformation. Mechanistic evidence suggests that this intramolecular arene/alkyne annulation may take place through unusual dual C-H activation followed by annulation with alkynes. © 2014 American Chemical Society.

Xu L.,Dalian University of Technology | Xu L.,CAS Institute of Theoretical Physics
Physical Review D - Particles, Fields, Gravitation and Cosmology | Year: 2013

The growth index γL was proposed to investigate the possible deviation from the standard ΛCDM model and Einstein's gravity theory in a dynamical perspective. Recently, thanks to the measurement of the cosmic growth rate via the redshift-space distortion, one can understand the evolution of the density contrast through fσ8(z), where f(z)=dlnâ;δ/dlnâa is the growth rate of matter and σ8(z) is the rms amplitude of the density contrast δ at the comoving 8h-1 Mpc scale. In this paper, we use the redshift-space distortion data points to study the growth index on the bases of Einstein's gravity theory and a modified gravity theory under the assumption of f=Ωm(a)γL. The cosmic background evolution is fixed by the cosmic observations from the type Ia supernovae SNLS3 data, cosmic microwave background radiation data from Planck, and baryon acoustic oscillations. Via the Markov Chain Monte Carlo method, we find the following γL values for Einstein's gravity with a cosmological constant (w=const) dark energy and a modified gravity theory in the 1, 2, and 3σ regions, respectively: 0.675-0.0662-0.120-0.155+0.0611+0.129+0.178, 0.745-0.0819-0.146-0.190+0.0755+0.157+0.205, and 0.555-0.0167-0.0373-0.0516+0. 0193+0.0335+0.0436. In Einstein's gravity theory, the values of the growth index γL show an almost 2σ deviation from the theoretical prediction of 6/11 for the ΛCDM model. However, in the modified gravity framework, a deviation from Einstein's relativity is not detected in the 1σ region. This implies that the currently available cosmic observations do not predict an alternative modified gravity theory beyond the ΛCDM model under Einstein's gravity, but that the simple assumption of f=ΩmγL should be improved. © 2013 American Physical Society.

Gu Y.,Hohai University | Chen W.,Hohai University | Chen W.,Dalian University of Technology | He X.-Q.,City University of Hong Kong
International Journal of Heat and Mass Transfer | Year: 2012

The singular boundary method (SBM) is a recent strong-form meshless boundary collocation method. Like the method of fundamental solutions (MFS), the SBM uses the fundamental solution of the governing differential equation of interest as the basis function and is mathematically simple, truly meshless, accurate, and easy-to-program. Unlike the MFS, the SBM, however, uses the concept of the origin intensity factor to isolate the singularity of the fundamental solutions and overcomes the fictitious boundary issue which has long perplexed the MFS. This study makes the first attempt to apply the SBM to steady-state heat conduction in three-dimensional (3D) anisotropic materials. Five benchmark numerical examples demonstrate that the SBM is accurate, convergent, stable, and computationally efficient in solving this kind of problems. © 2012 Elsevier Ltd. All rights reserved.

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.

Fu Z.-J.,Hohai University | Fu Z.-J.,Dalian University of Technology | Chen W.,Hohai University | Chen W.,Dalian University of Technology | Yang H.-T.,Dalian University of Technology
Journal of Computational Physics | Year: 2013

This paper develops a novel boundary meshless approach, Laplace transformed boundary particle method (LTBPM), for numerical modeling of time fractional diffusion equations. It implements Laplace transform technique to obtain the corresponding time-independent inhomogeneous equation in Laplace space and then employs a truly boundary-only meshless boundary particle method (BPM) to solve this Laplace-transformed problem. Unlike the other boundary discretization methods, the BPM does not require any inner nodes, since the recursive composite multiple reciprocity technique (RC-MRM) is used to convert the inhomogeneous problem into the higher-order homogeneous problem. Finally, the Stehfest numerical inverse Laplace transform (NILT) is implemented to retrieve the numerical solutions of time fractional diffusion equations from the corresponding BPM solutions. In comparison with finite difference discretization, the LTBPM introduces Laplace transform and Stehfest NILT algorithm to deal with time fractional derivative term, which evades costly convolution integral calculation in time fractional derivation approximation and avoids the effect of time step on numerical accuracy and stability. Consequently, it can effectively simulate long time-history fractional diffusion systems. Error analysis and numerical experiments demonstrate that the present LTBPM is highly accurate and computationally efficient for 2D and 3D time fractional diffusion equations. © 2012 Elsevier Inc.

Sun H.,Dalian University of Technology | Sun H.,University of Jinan | Yue C.-X.,Liaoning Normal University
European Physical Journal C | Year: 2014

We study the photoproduction of the charged top-pion predicted by the top triangle moose (TTM) model (a deconstructed version of the topcolor-assisted technicolor TC2 model) via the processes (Formula presented.) at the 14 TeV Large Hadron Collider (LHC) including next-to-leading order (NLO) QCD corrections. Our results show that the production cross sections and distributions are sensitive to the free parameters sinω and Mπt. A typical QCD correction value is 7-11% and this does not depend much on sinω as well as the forward detector acceptances. © 2014 The Author(s).

Wang W.,Dalian University of Technology | Wang W.,Jilin University | Liu X.,Dalian University of Technology
Information Sciences | Year: 2015

In spite of the impressive diversity of models of fuzzy forecasting, there is still a burning need to arrive at models that are both accurate and highly interpretable. This study proposes a new fuzzy forecasting model designed with the use of the two key techniques, namely clustering and axiomatic fuzzy set (AFS) classification. First, clustering algorithm is utilized to generate clustering-based intervals. Second, the fuzzy trend labeled training data set is constructed based on fuzzy logic relationships and fuzzy trends of historical samples. Then, the AFS classification is exploited to yield the semantic interpretation of each fuzzy trend. The main novelty is that the proposed model not only predicts the value but can also capture the trend prevailing in the time series, and obtain its semantic interpretation. The Taiwan Stock Exchange Capitalization Weighted Stock Index (TAIEX), inventory demand, and Spanish electricity prices are used in a series of experiments. The results show that the proposed model has both good interpretability and accuracy. © 2014 Elsevier Inc. All rights reserved.

Lu S.,Tohoku University | Lu S.,Dalian University of Technology | Jin T.,Tohoku University | Kwon E.,Tohoku University | And 2 more authors.
Angewandte Chemie - International Edition | Year: 2012

Dimers are a girl's best friend: The title reaction allows the formation of single-bonded fullerene dimers with extremely high chemical yield and high compatibility with various functional groups, which are highly soluble in organic solvents. The use of Cu(OAc) 2 catalyst with dimethylformamide or acetonitrile as additives under air is the critical factor in achieving the highly efficient catalytic dimerization. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

He Z.-j.,Tsinghua University | Song Y.-p.,Dalian University of Technology
Cement and Concrete Research | Year: 2010

Triaxial tests were performed on 100 mm × 100 mm × 100 mm cubic specimens of plain high-strength and high-performace concrete (HSHPC) at all kinds of stress ratios after exposure to normal and high temperatures of 20, 200, 300, 400, 500, and 600 °C, using a large static-dynamic true triaxial machine. Friction-reducing pads, using three layers of plastic membrane with glycerine were placed between the compressive loading plate and the specimens; the tensile loading planes of concrete samples were processed by an attrition machine, and then the samples were glued-up with the loading plate with structural glue. The failure mode characteristic of the specimens and the direction of the crack were observed and described. The three principally static strengths in the corresponding stress state were measured. The influence of the temperatures and stress ratios on the triaxial strengths of HSHPC after exposure to high temperatures was also analyzed. The experimental results showed that the uniaxial compressive strength of plain HSHPC after exposure to high temperatures does not decrease completely with the increase in temperature, the ratios of the triaxial to its uniaxial compressive strength are dependent on the brittleness-stiffness of HSHPC after different temperatures and the stress ratios. On this basis, a new failure criterion with the temperature parameters is proposed for plain HSHPC under multiaxial stress states. It provides the experimental and theoretical foundations for strength analysis of HSHPC structures subject to complex loads after subjected to a high temperature environment. © 2009 Elsevier Ltd. All rights reserved.

Cong J.,Dalian University of Technology | Yang X.,Dalian University of Technology | Kloo L.,Molecular Devices | Sun L.,Dalian University of Technology | Sun L.,Molecular Devices
Energy and Environmental Science | Year: 2012

Dye-sensitized solar cells have attracted intense academic interest over the past two decades. For a long time, the development of new redox systems has fallen far behind that of the sensitizing dyes and other materials. However, the field has received renewed attention recently. In particular, in 2011, the Grätzel group published a record DSC efficiency of 12.3% by using a new Co-complex-based electrolyte. In this review, we will provide an overview of iodine/iodide-free redox systems for liquid electrolytes, and reveal that the design of an efficient redox system should combine with appropriate sensitizing dyes which is the pivotal challenge for highly efficient DSCs. © 2012 The Royal Society of Chemistry.

He R.,CAS Institute of Automation | Hu B.-G.,CAS Institute of Automation | Zheng W.-S.,Sun Yat Sen University | Kong X.-W.,Dalian University of Technology
IEEE Transactions on Image Processing | Year: 2011

Principal component analysis (PCA) minimizes the mean square error (MSE) and is sensitive to outliers. In this paper, we present a new rotational-invariant PCA based on maximum correntropy criterion (MCC). A half-quadratic optimization algorithm is adopted to compute the correntropy objective. At each iteration, the complex optimization problem is reduced to a quadratic problem that can be efficiently solved by a standard optimization method. The proposed method exhibits the following benefits: 1) it is robust to outliers through the mechanism of MCC which can be more theoretically solid than a heuristic rule based on MSE; 2) it requires no assumption about the zero-mean of data for processing and can estimate data mean during optimization; and 3) its optimal solution consists of principal eigenvectors of a robust covariance matrix corresponding to the largest eigenvalues. In addition, kernel techniques are further introduced in the proposed method to deal with nonlinearly distributed data. Numerical results demonstrate that the proposed method can outperform robust rotational-invariant PCAs based on L1 norm when outliers occur. © 2010 IEEE.

Zhao J.,Tohoku University | Oniwa K.,Tohoku University | Asao N.,Tohoku University | Yamamoto Y.,Tohoku University | And 2 more authors.
Journal of the American Chemical Society | Year: 2013

A novel and selective Pd-catalyzed cascade crossover-annulation of o-alkynylarylhalides and diarylacetylenes for the synthesis of dibenzo[a,e]pentalenes has been reported. Various arylacetylenes with a wide range of functional groups were tolerated, producing the corresponding multisubstituted dibenzopentalenes with the different substituents on the aromatic rings in good to high yields under the optimized reaction conditions. The reaction proceeds through a Pd-catalyzed cascade carbopalladation and C-H activation. The use of the combined DBU and CsOPiv bases is crucial for the successful implementation of the present cross-annulation. © 2013 American Chemical Society.

Yang Y.-F.,Dalian University of Technology | Hou C.,Tsinghua University
Magazine of Concrete Research | Year: 2015

This paper describes research work on the performance and design calculations of recycled aggregate concrete filled steel tube (RACFST) members, especially the most recent developments in China. Firstly, experimental studies on RACFST members subjected to short-term static loading, long-term sustained loading and cyclic flexural loading are summarised and analysed, and recent advances in the behaviour of RACFST stub columns after exposure to high temperatures (300-8008C) are also reviewed. The experimental results show that, in general, RACFST members have similar performance to concrete filled steel tube (CFST) members when subjected to the same loading conditions. However, due to the more serious inherent defects of recycled aggregate concrete compared with normal concrete, RACFST members have a lower bearing capacity and stiffness than their CFST counterparts. Secondly, design formulae for RACFST members are suggested and the calculated bearing capacities using the simplified equations generally agree well with the experimental results. Finally, the potential research needs of RACFST structures are discussed.

Chen L.,Dalian University of Technology | Liu T.,Dalian University of Technology | Liu T.,Sun Yat Sen University | Zhou Y.,Dalian University of Technology | And 3 more authors.
Acta Crystallographica Section D: Biological Crystallography | Year: 2014

Insects possess a greater number of chitinases than any other organisms. This work is the first report of unliganded and oligosaccharide-complexed crystal structures of the insect chitinase OfChtI from Ostrinia furnacalis, which is essential to moulting. The obtained crystal structures were solved at resolutions between 1.7 and 2.2 Å. A structural comparison with other chitinases revealed that OfChtI contains a long substrate-binding cleft similar to the bacterial chitinase SmChiB from Serratia marcescens. However, unlike the exo-acting SmChiB, which has a blocked and tunnel-like cleft, OfChtI possesses an open and groove-like cleft. The complexed structure of the catalytic domain of OfChtI (OfChtI-CAD) with (GlcNAc)2/3 indicates that the reducing sugar at subsite-1 is in an energetically unfavoured 'boat' conformation, a state that possibly exists just before the completion of catalysis. Because OfChtI is known to act from nonreducing ends, (GlcNAc)3 would be a hydrolysis product of (GlcNAc)6, suggesting that OfChtI possesses an endo enzymatic activity. Furthermore, a hydrophobic plane composed of four surface-exposed aromatic residues is adjacent to the entrance to the substrate-binding cleft. Mutations of these residues greatly impair the chitin-binding activity, indicating that this hydrophobic plane endows OfChtI-CAD with the ability to anchor chitin. This work reveals the unique structural characteristics of an insect chitinase. © 2014 International Union of Crystallography.

Yang Y.-F.,Dalian University of Technology | Han L.-H.,Tsinghua University | Sun B.-H.,Dalian University of Technology
Journal of Constructional Steel Research | Year: 2012

The experimental behaviour of concrete filled double-skin steel tube (CFDST) sections subjected to partial compression is reported in this paper. Fourteen specimens with outer and inner steel tubes of circular hollow section (CHS) and fifteen specimens with outer and inner steel tubes of square hollow section (SHS) were tested. The test parameters included: 1) hollow ratio, 2) top endplate thickness, and 3) partial compression area ratio. The test results indicated that the CFDST columns under partial compression behaved in a ductile manner. The partial compressive behaviour and the failure modes of partially loaded CFDST stub columns were significantly affected by the parameters investigated. Finally, a simplified model for predicting the bearing capacity of partially loaded CFDST sections is proposed. © 2011 Elsevier Ltd. All rights reserved.

Zhang S.,Bohai University | Zhang S.,Dalian University of Technology | Zhang H.-Q.,Dalian University of Technology
Physics Letters, Section A: General, Atomic and Solid State Physics | Year: 2011

A fractional sub-equation method is proposed to solve fractional differential equations. To illustrate the effectiveness of the method, the nonlinear time fractional biological population model and (4+1)-dimensional space-time fractional Fokas equation are considered. As a result, three types of exact analytical solutions are obtained. © 2011 Elsevier B.V. All rights reserved.

Huang H.,University of Texas Southwestern Medical Center | Fan X.,Dalian University of Technology | Williamson D.E.,University of Texas Health Science Center at San Antonio | Rao U.,Southwestern Medical Center
Neuropsychopharmacology | Year: 2011

Alterations in white matter integrity of several cortical and subcortical circuits have been reported in relation to unipolar major depressive disorder. It is not clear whether these white matter changes precede the onset of illness. In all, 13 adolescent volunteers with no personal or family history of a psychiatric disorder (controls) and 18 adolescent volunteers with no personal history of a psychiatric illness including depression, but who were at high risk for developing unipolar depression by virtue of parental depression (high-risk youth), underwent diffusion tensor imaging studies. An automated tract-based spatial statistics method, a whole-brain voxel-by-voxel analysis, was used to analyze the scans. Population average diffusion parameter values were also calculated for each tract. Adolescents at high risk for unipolar depression had lower fractional anisotropy (FA) values in the left cingulum, splenium of the corpus callosum, superior longitudinal fasciculi, uncinate, and inferior fronto-occipital fasciculi than did controls. Altered white matter integrity in healthy adolescents at familial risk for unipolar depression suggests that it might serve as a vulnerability marker for the illness. © 2011 American College of Neuropsychopharmacology. All rights reserved.

Yang Y.-F.,Dalian University of Technology | Han L.-H.,Tsinghua University
Thin-Walled Structures | Year: 2011

This paper investigates the behaviour of concrete filled steel tubular (CFST) stub columns subjected to eccentric partial compression. Twenty-eight specimens were tested and presented. The main parameters in test program include: (1) section type: circular, square and rectangular; (2) load eccentricity ratio (including uniaxial and biaxial loading): from 0 to 0.4; and (3) shape of the loading bearing plate (BP): circular, square, strip and rectangular. The test results indicated that, similar to the corresponding fully loaded CFST stub columns under eccentric loading, CFST stub columns under eccentric partial compression have generally reasonable bearing capacity and favorable ductility. A finite element analysis (FEA) model for CFST stub columns under eccentric partial compression is developed and the predicted performances are validated through measured results. The FEA model is then used to investigate the mechanisms of such composite columns further. © 2010 Elsevier Ltd. All rights reserved.

Takale B.S.,Dalian University of Technology | Bao M.,Dalian University of Technology | Yamamoto Y.,Dalian University of Technology | Yamamoto Y.,Tohoku University
Organic and Biomolecular Chemistry | Year: 2014

Organic synthesis using gold has gained tremendous attention in last few years, especially heterogeneous gold catalysis based on gold nanoparticles has made its place in almost all organic reactions, because of the robust and green nature of gold catalysts. In this context, gold nanopore (AuNPore) with a 3D metal framework is giving a new dimension to heterogeneous gold catalysts. Interestingly, AuNPore chemistry is proving better than gold nanoparticles based chemistry. In this review, along with recent advances, major discoveries in heterogeneous gold catalysis are discussed. © 2014 The Royal Society of Chemistry.

Chang B.,Dalian University of Technology | Xu L.,Dalian University of Technology | Xu L.,CAS Institute of Theoretical Physics
Physical Review D - Particles, Fields, Gravitation and Cosmology | Year: 2014

We use currently available cosmic observations to probe and constrain an imperfect dark-energy fluid that is characterized by a constant equation of state w and a constant speed of viscosity cvis2. The model parameter space was scanned using the Markov chain Monte Carlo method. The results show that the speed of viscosity cvis2 was not well constrained when currently available data sets are used (including the cosmic microwave background radiation from Planck-2013 and WMAP9, type Ia supernovae, baryon acoustic oscillations, redshift space distortion fσ8(z), and gravitational weak lensing from Canada-France Hawaii Telescope Lensing Survey (CFHTLenS). However, the cosmic data sets slightly favor phantom dark energy with a negative speed of viscosity cvis2. © 2014 American Physical Society.

Yang W.,Dalian University of Technology | Xu L.,Dalian University of Technology | Xu L.,CAS Institute of Theoretical Physics
Physical Review D - Particles, Fields, Gravitation and Cosmology | Year: 2014

The coupling between dark sectors provides a possible approach to mitigate the coincidence problem of the cosmological standard model. In this paper, dark energy is treated as a fluid with a constant equation of state, whose coupling with dark matter is proportional the Hubble parameter and energy density of dark energy, that is, Q¯=3ξxH¯ρ¯x. In particular, we consider the Hubble expansion rate to be perturbed in the perturbation evolutions of dark sectors. Using joint data sets which include cosmic microwave background radiation, baryon acoustic oscillation, type Ia supernovae, and redshift-space distortions, we perform a full Markov chain Monte Carlo likelihood analysis for the coupled model. The results show that the mean value with errors of the interaction rate is ξx=0.00305-0.00305-0.00305-0.00305+0.000645+0.00511+0.00854 for QAμ∥ucμ and ξx=0.00317-0.00317-0.00317-0.00317+0.000628+0.00547+0.00929 for QAμ∥uxμ, which means that the recent cosmic observations favor a small interaction rate which is up to the order of 10-3. Moreover, in contrast to the coupled model with an unperturbed expansion rate, we find the perturbed Hubble expansion rate can bring about a negligible impact on the model parameter space. © 2014 American Physical Society.

Jin T.,Tohoku University | Zhao J.,Tohoku University | Asao N.,Tohoku University | Yamamoto Y.,Tohoku University | Yamamoto Y.,Dalian University of Technology
Chemistry - A European Journal | Year: 2014

The progress of the metal-catalyzed annulation reactions toward construction of various π-conjugated polycyclic cores with high conjugation extension is described. This article gives a brief overview of various annulation reactions promoted by metal catalysts including C-H bond functionalization, [2+2+2] cycloaddition, cascade processes, ring closing metathesis, electrophilic aromatization, and various cross-coupling reactions. A variety of conjugated polycycles with planar, bowl-shaped, and helical structures have been constructed in high efficiency and selectivity. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Bull S.D.,University of Bath | Davidson M.G.,University of Bath | Van Den Elsen J.M.H.,University of Bath | Fossey J.S.,University of Birmingham | And 7 more authors.
Accounts of Chemical Research | Year: 2013

Boronic acids can interact with Lewis bases to generate boronate anions, and they can also bind with diol units to form cyclic boronate esters. Boronic acid based receptor designs originated when Lorand and Edwards used the pH drop observed upon the addition of saccharides to boronic acids to determine their association constants. The inherent acidity of the boronic acid is enhanced when 1,2-, 1,3-, or 1,4-diols react with boronic acids to form cyclic boronic esters (5, 6, or 7 membered rings) in aqueous media, and these interactions form the cornerstone of diol-based receptors used in the construction of sensors and separation systems.In addition, the recognition of saccharides through boronic acid complex (or boronic ester) formation often relies on an interaction between a Lewis acidic boronic acid and a Lewis base (proximal tertiary amine or anion). These properties of boronic acids have led to them being exploited in sensing and separation systems for anions (Lewis bases) and saccharides (diols).The fast and stable bond formation between boronic acids and diols to form boronate esters can serve as the basis for forming reversible molecular assemblies. In spite of the stability of the boronate esters' covalent B-O bonds, their formation is reversible under certain conditions or under the action of certain external stimuli.The reversibility of boronate ester formation and Lewis acid-base interactions has also resulted in the development and use of boronic acids within multicomponent systems. The dynamic covalent functionality of boronic acids with structure-directing potential has led researchers to develop a variety of self-organizing systems including macrocycles, cages, capsules, and polymers.This Account gives an overview of research published about boronic acids over the last 5 years. We hope that this Account will inspire others to continue the work on boronic acids and reversible covalent chemistry. © 2012 American Chemical Society.

He R.,CAS Institute of Automation | Zheng W.-S.,Sun Yat Sen University | Hu B.-G.,CAS Institute of Automation | Kong X.-W.,Dalian University of Technology
IEEE Transactions on Neural Networks and Learning Systems | Year: 2013

This paper proposes a novel nonnegative sparse representation approach, called two-stage sparse representation (TSR), for robust face recognition on a large-scale database. Based on the divide and conquer strategy, TSR decomposes the procedure of robust face recognition into outlier detection stage and recognition stage. In the first stage, we propose a general multisubspace framework to learn a robust metric in which noise and outliers in image pixels are detected. Potential loss functions, including L1, L 2,1, and correntropy are studied. In the second stage, based on the learned metric and collaborative representation, we propose an efficient nonnegative sparse representation algorithm to find an approximation solution of sparse representation. According to the L1 ball theory in sparse representation, the approximated solution is unique and can be optimized efficiently. Then a filtering strategy is developed to avoid the computation of the sparse representation on the whole large-scale dataset. Moreover, theoretical analysis also gives the necessary condition for nonnegative least squares technique to find a sparse solution. Extensive experiments on several public databases have demonstrated that the proposed TSR approach, in general, achieves better classification accuracy than the state-of-the-art sparse representation methods. More importantly, a significant reduction of computational costs is reached in comparison with sparse representation classifier; this enables the TSR to be more suitable for robust face recognition on a large-scale dataset. © 2012 IEEE.

Lian J.,Dalian University of Technology | Mu C.,Dalian University of Technology | Shi P.,University of South Wales | Shi P.,Victoria University of Melbourne | Shi P.,University of South Australia
Information Sciences | Year: 2013

This paper considers the H∞ filtering problem of discrete-time switched delay systems. Attention is focused on the design of an exponentially mean-square stable filter taking the asynchronous switching and missing measurements into account. New results on exponential mean-square stability and a weighted l2-gain analysis for filtering error system are given. The closed-loop system is allowed to be unstable during the unmatched interval in which the switching signal of filter is different from that of the system. By using the average dwell time (ADT) and the Lyapunov-Krasovskii function methods, delay-dependent sufficient conditions for the desired H ∞ filter are derived in terms of linear matrix inequalities (LMIs). A numerical example is provided to demonstrate the effectiveness of the proposed design approach. © 2012 Elsevier Inc. All rights reserved.

Zhang X.F.,Dalian University of Technology | Guan P.F.,Tohoku University | Dong X.L.,Dalian University of Technology
Applied Physics Letters | Year: 2010

Hybrid core/shell Co/graphite nanoparticles synthesized by an arc-discharge method exhibit an enhanced dielectric loss property in the frequency range of 2-18 GHz. Complex permittivity expressed by Debye dipolar polarization approximate show that three kinds of dielectric polarizations coexist in this hybrid system. Combined with theoretical simulation, we further clarified that the dielectric polarizations are ascribed to the high defective graphite shells, and additional interfacial polarizations arising from the special core/shell architecture. © 2010 American Institute of Physics.

Zhang X.F.,Dalian University of Technology | Guan P.F.,Tohoku University | Dong X.L.,Dalian University of Technology
Applied Physics Letters | Year: 2010

We report an anomalously electromagnetic resonance in a simple Ni nanoparticle/paraffin system. The resonance, caused by the near-field interaction of nanoparticles, appears at ∼16 GHz as decreasing the interparticle distance down to ∼11 nm. It is associated with an unusual energy transfer from the permeability to permittivity, resulting in the enhanced dielectric and weakened magnetic attenuations. These experimental results can be well modeled by a numerical simulation, evidencing the enhanced electrical filed distribution as decreasing the interaction distance. This study enables us to first realize the permeability-to-permittivity transform of electromagnetic wave in nanocomposites. © 2010 American Institute of Physics.

Nishina N.,University of Shizuoka | Yamamoto Y.,Dalian University of Technology | Yamamoto Y.,Tohoku University
Topics in Organometallic Chemistry | Year: 2013

This chapter describes late transition metal complexes-catalyzed hydroamination, the formal addition of an H-N bond across a C-C multiple bond. Late transition metal catalysis has been intensely developed in the hydroamination and additions of various kinds of amines to C-C multiple bonds have been achieved. The reaction pathways strongly depend on the choice of metal complexes, substrates, and reaction conditions. This chapter is organized primarily based on the difference in the mechanisms of hydroamination reactions, and in the scope section concise summary of the hydroamination reaction is shown. © 2013 Springer-Verlag Berlin Heidelberg.

Wang D.,Dalian University of Technology | Shi P.,University of South Wales | Wang W.,Dalian University of Technology
IET Control Theory and Applications | Year: 2010

This study addresses the robust fault detection problem for continuous-time switched systems with state delays. The fault detection filter is used as the residual generator depending on the system mode. Attention is focused on designing the filter such that, for the modelling errors, the unknown inputs and the control one, the error between the residuals and the faults is minimised. The addressed fault detection filter design is converted into an auxiliary H∞ filtering problem. By using the Lyapunov-Krasovskii functional method and average dwell time approach, a sufficient condition for the solvability of this problem is established in terms of linear matrix inequalities (LMIs). Two examples are provided to demonstrate the effectiveness of the proposed method. © 2010 The Institution of Engineering and Technology.

Lu S.,Tohoku University | Lu S.,Dalian University of Technology | Jin T.,Tohoku University | Bao M.,Dalian University of Technology | Yamamoto Y.,Tohoku University
Journal of the American Chemical Society | Year: 2011

The Co-catalyzed hydroalkylation of C 60 with reactive alkyl bromides 1 (RBr) in the presence of Mn reductant and H 2O at ambient temperature gave the monoalkylated C 60 (2) in good to high yields. The use of CoLn/Mn/H 2O under Ar atmosphere is crucial for the success of the present transformation. The reaction most probably proceeds through the Co(0 or I) complex-promoted generation of a radical (R •) followed by addition to C 60. This hydroalkylation method was applied to the synthesis of zinc porphyrin attached C 60 (2l), dendrimer attached C 60 (2m), and fullerene dimer (2n), which were not easily available through the previously known methods. © 2011 American Chemical Society.

Wang W.,Guangdong Ocean University | Li F.,Dalian University of Technology
Optics and Lasers in Engineering | Year: 2014

We propose an efficient approach to develop large-range liquid level sensors based on an extrinsic Fabry-Perot optical fibre interferometer with an all fused-silica structure and CO2 laser heating fusion bonding technology. The sensor exhibits signatures of a high sensitivity of 5.3 nm/kPa (36.6 nm/psi), a resolution of 6.8 Pa (9.9×10-4 psi) and an extreme low temperature dependence of 0.013 nm/ C. As a result, a high resolution of the water level measurement of approximately 0.7 mm on the length scale of 5 m and small errors of the water pressure measurement induced by the temperature dependence within 0.0025 kPa/ C (0.00036 psi/ C, water level 0.25 mm/ C) are achieved, thus providing useful applications for the detection of the large-range liquid level in harsh environments. © 2013 Elsevier Ltd.

Wang J.,Dalian University of Technology | Han F.,Tsinghua University | Cheng G.,Beijing Special Engineering Design and Research Institute | Zhao F.,Dalian University of Technology
International Journal of Machine Tools and Manufacture | Year: 2012

Debris accumulation in the discharge gap causes a poor machining stability and low production efficiency. Thus, an understanding on the mechanism of debris exclusion in electrical discharge machining is important. However, to date, this mechanism has not been fully understood because of the difficulty in observing debris movements in discharge gaps. The current study established a series of experimental devices using transparent materials to observe debris and bubble movements. Based on the observations, the mechanism of debris and bubble exclusion during consecutive pulse discharges is analyzed, and the effects of the electrode jump height and speed on the debris and bubble movements are investigated. In addition, the effectiveness of the debris and bubble movements on machining efficiency is discussed. © 2012 Elsevier Ltd. All rights reserved.

Yang Y.F.,Dalian University of Technology | Han L.H.,Tsinghua University
Thin-Walled Structures | Year: 2012

This paper studies the behaviour of thin-walled concrete filled steel tube (CFST) column subjected to concentrically partial compression. A series of tests was carried out to investigate the effects of sectional type, length-to-diameter (width) ratio, partial compression area ratio and top endplate thickness on the behaviour and bearing capacity of partially loaded CFST column. Twenty-six CFST specimens were tested, and the bearing capacity, load versus deformation relation and failure mode of the specimens were obtained. It was shown that the CFST columns under concentrically partial compression generally had reasonable bearing capacity and ductility. A finite element analysis (FEA) model was developed for simulating the behaviour of CFST column subjected to concentrically partial compression, and a comparison of the performances predicted using this model showed generally good agreement with the test results. The FEA model was then used for the mechanism analysis of CFST column subjected to concentrically partial compression. Finally, a simplified model that could be used to predict the bearing capacity of the composite column under concentrically partial compression was proposed. © 2011 Elsevier Ltd. All rights reserved.

Zhao B.,Tsinghua University | Yu Q.,Tsinghua University | Leng Z.,Dalian University of Technology | Chen X.,Dalian University of Technology
IEEE Transactions on Industrial Electronics | Year: 2012

This paper presents a novel switched Z-source isolated bidirectional dc-dc converter. The converter employs two unique switched impedance networks to couple the main circuit and the power source and load. Compared with the traditional isolated bidirectional dc-dc converter, the proposed converter has a wider regulation range of voltage. In addition, due to the fully symmetrical circuit configuration, there is neither a high-voltage side nor a low-voltage side in the circuit structure, and the sources connected to the dc side of each H-bridge can be both voltage sources and current sources. At the same time, the converter can bear shoot-through phenomenon in H-bridges, so it has high reliability. The topology configuration and operating principle of this converter are analyzed, and a unique phase-shifting shoot-through bivariate coordinated control strategy is designed and implemented. Both simulation and experimental results verify the analytical results. © 2011 IEEE.

He Z.-j.,Tsinghua University | Song Y.-p.,Dalian University of Technology
Construction and Building Materials | Year: 2010

Multiaxial tensile-compressive tests were performed on 100 mm × 100 mm × 100 mm cubic specimens of plain high-performance concrete (HPC) at all kinds of stress ratios after exposure to normal and high temperatures of 20, 200, 300, 400, 500, and 600 °C, using a large static-dynamic true triaxial machine. Friction-reducing pads were three layers of plastic membrane with glycerine in-between for the compressive loading plane; the tensile loading planes of concrete samples were processed by attrition machine, and then the samples were glued-up with the loading plate with structural glue. The failure mode characteristic of specimens and the direction of the crack were observed and described, respectively. The three principally static strengths in the corresponding stress state were measured. The influence of the temperatures, stress ratios, and stress states on the triaxial strengths of HPC after exposure to high temperatures were also analyzed respectively. The experimental results showed that the uniaxial compressive strength of plain HPC after exposure to high temperatures does not decrease completely with the increase in temperature, the ratios of the triaxial to its uniaxial compressive strength depend on brittleness-stiffness of HPC after different high temperatures besides the stress states and stress ratios. On this basis, the formula of a new failure criterion with the temperature parameters under multiaxial tensile-compressive stress states for plain HPC is proposed. This study is helpful to reveal the multiaxial mechanical properties of HPC structure enduring high temperatures, and provides the experimental and theory foundations (testing data and correlated formula) for fire-resistant structural design, and for structural safety assessment and maintenance after fire. © 2009 Elsevier Ltd. All rights reserved.

Ninestar Management Co. and Dalian University of Technology | Date: 2011-03-23

The invention is related to a weather-resistant dye and use thereof, which contains in molecules thereof not only chromophoric parent D, but also electron-accepting group Q which is linked with dye parent D through non-conjugated carbon link L to constitute D-L-Q dye molecule; the electron-accepting group Q has such a HOMO energy level that is lower than the HOMO energy level of the dye chromophoric parent D. The dye has sun-resistance and anti-ozone performances, which can be used as colorant in the ink, dope, lacquer, toner powder for laser printing, marker, paper, fabric, glass, porcelain or polymer.

Dalian University of Technology and Ninestar Management Co. | Date: 2013-01-16

The present invention relates to a class of compounds of general formula (I) or their salts of general formula (II): In formula (I)-(II), the substituents (A)p and (SO_(3)H)n on the benzene ring are at the ortho, meta or para position, n is 0-2, and p is 0-3 M is selected from Li^(+), Na^(+), K^(+), NH_(4)^(+) or organic ammonium salt N^(+)R_(1)R_(2)R_(3)R_(4), where R_(1), R_(2), R_(3), R_(4) are the same or different H, C_(1-18) alkyl groups, cyclohexyl groups, CH_(2)CH_(2)OH, CH(CH_(3))CH_(2)OH or benzyl groups; where p > 0, A stands for the same or different groups selected from: H, CN, NO_(2), NH_(2), F, Cl, Br, C_(1-18) alkyl group, cyclohexyl group, phenyl group, benzyl group, phenoxy group, C_(1)-_(18) alkoxy group, C_(1-18) alkylthio group, SO_(2)CH=CH_(2), SO_(2)CH_(2)CH_(2)A_(1), NR_(6)COR_(5) or NR_(6)SO_(2)R_(5).

Li M.-W.,Dalian University of Technology | Hong W.-C.,Oriental Institute of Technology | Kang H.-G.,Dalian University of Technology
Neurocomputing | Year: 2013

In order to improve forecasting accuracy of urban traffic flow, this paper applies support vector regression (SVR) model with Gauss loss function (namely Gauss-SVR) to forecast urban traffic flow. By using the input historical flow data as the validation data, the Gauss-SVR model is dedicated to reduce the random error of the traffic flow data sequence. The chaotic cloud particle swarm optimization algorithm (CCPSO) is then proposed, based on cat chaotic mapping and cloud model, to optimize the hyper parameters of the Gauss-SVR model. Finally, the Gauss-SVR model with CCPSO is established to conduct the urban traffic flow forecasting. Numerical example results have proved that the proposed model has received better forecasting performance compared to existing alternative models. Thus, the proposed model has the feasibility and the availability in urban traffic flow forecasting fields. © 2012 Elsevier B.V.

Zhang L.,Dalian University of Technology | Yin Y.,University of Florida | Chen S.,University of Florida
Transportation Research Part C: Emerging Technologies | Year: 2013

This paper formulates a bi-objective optimization model to determine timing plans for coordinated traffic signals along arterials to minimize traffic delay and the risk associated with human exposure to traffic emissions. Based on a cell-transmission representation of traffic dynamics, a modal sensitive emission approach is used to estimate the tailpipe emission rate for each cell of a signalized arterial. A cell-based Gaussian plume air dispersion model is then employed to capture the dispersion of air pollutants and compute the roadside pollutant concentrations. A measure of mean excess exposure is further defined to represent the risk associated with human exposure to traffic pollutants under the wind uncertainty. A signal timing optimization model is formulated to optimize the cycle length, offsets, green splits and phase sequences to minimize the total system delay and the mean excess exposure simultaneously. The bi-objective optimization model is solved via a simulation-based genetic algorithm to find a set of Pareto optimal solutions. A numerical example is presented to demonstrate the model. © 2013 Elsevier Ltd.

Leus K.,Ghent University | Liu Y.-Y.,Ghent University | Liu Y.-Y.,Dalian University of Technology | Van Der Voort P.,Ghent University
Catalysis Reviews - Science and Engineering | Year: 2014

Since the discovery of Metal Organic Frameworks (MOFs) in the early 1990s, the amount of new structures has grown exponentially. A MOF typically consists of inorganic nodes that are connected by organic linkers to form crystalline, highly porous structures. MOFs have attracted a lot of attention lately, as the versatile design of such materials holds promises of interesting applications in various fields. In this review, we will focus on the use of MOFs as heterogeneous oxidation catalysts. MOFs are very promising candidates to replace homogeneous catalysts by sustainable and stable heterogeneous catalysts. The catalytic active function can be either the active metal sites of the MOF itself or can be introduced as an extra functionality in the linker, a dopant or a "ship-in-a-bottle" complex. As the pore size, pore shape, and functionality of MOFs can be designed in numerous ways, shape selectivity, and even chiral selectivity can be created. In this article, we will present an overview on the state of the art of the use of MOFs as a heterogeneous catalyst in liquid phase oxidation reactions. © 2014 Taylor and Francis Group, LLC.

Zhao J.,South China University of Technology | Wu B.,Harbin Institute of Technology | Ou J.,Dalian University of Technology
Journal of Structural Engineering (United States) | Year: 2012

In a previous study by the authors, the cyclic behavior of a novel type of pin-connected angle steel buckling-restrained brace (ABRB) was examined, and the failure mechanism in the core projection of the ABRB induced by an excessive bending effect caused by end rotation was discussed. In this paper, the occurrence mechanism of end rotation modes and the bending effect in the core projection of an ABRB are first investigated based on the previous test results, which shows that end rotation demands would be significantly increased with the presence of a gap and an additional bending effect could be observed if the end rotation demands were large enough to cause two-point contact at the core ends. Then, a new method to predict the flexural demand on pin-connected BRBs is proposed by considering the effect of the end rotation modes, clearance, initial eccentricity, and initial deflection of casing. The design criteria to prevent yielding of the core projection are presented and further verified by the previous test results. Furthermore, the effects of key influential parameters on the flexural demand on core projection are discussed based on the analytical results. It is found that such a bending effect can be significantly reduced by decreasing the gap or increasing the constrained length of the core stiffening segment. The C-mode end rotation with single curvature bending configuration is found to be generally the most unfavorable case for core projection design. Finally, several design recommendations are provided for pin-connected BRBs. © 2012 American Society of Civil Engineers.

Zhao J.,Harbin Institute of Technology | Wu B.,Harbin Institute of Technology | Ou J.,Harbin Institute of Technology | Ou J.,Dalian University of Technology
Earthquake Engineering and Structural Dynamics | Year: 2011

A novel type of angle steel buckling-restrained brace (ABRB) has been developed for easier control on initial geometric imperfection in the core, more design flexibility in the buckling restraining mechanism and easier assembly work. The steel core is composed of four angle steels to form a non-welded cruciform shape restrained by two external angle steels, which are welded longitudinally to form an external tube. Component test was conducted on seven ABRB specimens under uniaxial quasi-static cyclic loading. The test results reveal that the consistency between the actual and design behavior of ABRB can be well achieved without the effect of weld in the core. The ABRBs with proper details exhibited stable cyclic behavior and satisfactory cumulative plastic ductility capacity, so that they can serve as effective hysteretic dampers. However, compression-flexure failure at the steel core projection was found to be the primary failure mode for the ABRBs with hinge connections even though the cross-section of the core projection was reinforced two times that of the yielding segment. The failure mechanism is further discussed by investigating the Nu- Mu correlation curve. It is found that the bending moment response developed in the core projection induced by end rotation was the main cause for such a failure mode, and it is suggested that core projection should be kept within elastic stage under the possible maximum axial load and bending moment response. © 2010 John Wiley & Sons, Ltd.

Jiang W.,Dalian University of Technology | Yahiaoui K.,University of Wolverhampton
International Journal of Pressure Vessels and Piping | Year: 2012

This paper presents a validated three-dimensional thermomechanical model to investigate the effect of the welding sequence on weld induced residual stress distributions in a multipass welded piping branch junction. Three possible symmetrical welding sequences, i.e. one-welder, two-welder and four-welder sequence, which were expected to generate the least adverse stress distributions in actual welding circumstances, were proposed and evaluated. It is shown that the variations of the predicted maximum stresses along the fusion lines are not large for the three proposed welding sequences, although at both the branch and run cross section, the four-welder model predicts the highest peak residual stresses while the one-welder model gives the lowest values. As would be expected, the stress distributions predicted by the four-welder and two-welder models show more symmetrical features than those by the one-welder model. High residual stress is formed in the vicinity of the weld region irrespective of the sequence of the welding. © 2012 Elsevier Ltd.

Sun X.-M.,Dalian University of Technology | Wu D.,Dalian University of Technology | Liu G.-P.,Dalian University of Technology | Liu G.-P.,Harbin Institute of Technology | Wang W.,Dalian University of Technology
IEEE Transactions on Industrial Electronics | Year: 2014

The input-to-state stability (ISS) for a class of networked control systems with random delays and packet dropouts appearing simultaneously in both feedback and forward channels is thoroughly investigated in this paper. A new network predictive controller scheme is introduced in order to compensate the effect of transmission delays and packet dropouts. By making use of the small gain theorem, the stability criteria of the considered new system are derived. The proposed stability conditions are fairly easy to check and considerably less conservative than the existing ones. These criteria reveal that, if the original linear systems are controllable and observable, then, by adopting the proposed networked-predictive-control scheme, the ISS properties can be guaranteed for the overall system despite the effects of networking such as transmission bounded delays, packet dropouts, and possible disturbance inputs. When no disturbance inputs occur, the system stability can be guaranteed for random delays with a certain bound or else for any large constant delays. Results for two illustrative examples are given to validate the proposed control scheme, the second one being a laboratory-scale dc-motor rig. © 2013 IEEE.

Xu B.,Dalian University of Technology | Zou D.,Dalian University of Technology | Liu H.,City College of New York
Computers and Geotechnics | Year: 2012

Concrete face rockfill dams (CFRDs) are becoming a widely used type of rockfill dam in China. In many cases, the design and construction of CFRDs are based primarily on precedent and engineering judgments. Few numerical or analytical methods have been developed to properly evaluate the deformation of CFRDs, which is important for dam safety and for subsequent evaluation of seismic performance. In this study, a finite element procedure was developed to simulate the construction process of a CFRD, using the Zipingpu CFRD in China as an illustrative example. The Zipingpu dam was subjected to a strong earthquake in 2008, and can be used as a benchmark problem to assess the safety of CFRD. It is thus important to the engineering community to establish the state of stress-strain in the dam prior to the earthquake. A generalized plasticity model was modified to better model the rockfill materials, and the interfaces between face slabs and cushions are modeled using zero-thickness interface elements that follow a hyperbolic stress-strain model in the tangential direction. The model parameters were calibrated by large-scale triaxial tests and direct shear tests performed on materials used in the dam. The step-by-step construction followed by subsequent impounding of the reservoir was simulated in the numerical procedure. The numerical results agree well with in situ monitoring records of dam settlements, indicating that a three-dimensional finite element procedure based on a modified generalized plasticity model and a hyperbolic interface model can be used to evaluate the deformation of CFRDs. © 2012 Elsevier Ltd.

Liu H.,City College of New York | Zou D.,Dalian University of Technology
Journal of Engineering Mechanics | Year: 2013

Gravelly soils are used extensively for a wide range of engineering applications. One example is railway ballast, and another is the fill for rock-filled dams. These soils are usually subjected to complicated loading, including high pressure, repeated loading from trains, and earthquake loading. Depending on the natural characteristics of soil particles and the level of external loading, gravelly soils may undergo particle breakage, which modifies the strength and deformation properties of the soils. To better estimate the response of earth structures with gravelly soils, it is necessary to describe particle breakage properly, its relation with external loading, and its effect on soil properties. In this study, a generalized plasticity framework, based on critical-state soil mechanics and following the associated flow rule, was developed based on the unique responses of gravelly soils. Particle breakage and its effects were described by a translating critical-state line that was related to dissipated plastic energy through a hyperbolic function. The responses of six gravelly soils along different stress paths were simulated using the proposed model. It was shown that with 12 parameters, the constitutive model was capable of describing the responses of gravelly soils over a wide range of initial void ratios and initial confining pressures, as well as along different stress paths. The model parameters, most of which have definite physical meanings, can be calibrated through conventional triaxial compression tests. This framework will provide a basis for simulating the cyclic responses of gravelly soils. ©2013 American Society of Civil Engineers.

Zhang X.F.,Dalian University of Technology | Zhang X.F.,National Research Council Canada | Huang H.,Dalian University of Technology | Dong X.L.,Dalian University of Technology
Journal of Physical Chemistry C | Year: 2013

We report an empirical thermodynamic law for the synthesis of core/shell metal/heterogeneous oxide nanocapsules, such as Fe/SiO2, Ni/SiO 2, Fe/B2O3, Ni/B2O3, Fe/Al2O3, Fe/MnO2, Fe/Y2O 3, Fe/CeO2, and Fe/La2O3, by arc-discharge evaporating a compressed mixture of Fe (or Ni) powders and the oxide powders of shell components. By integrating such dielectric oxide shells and magnetic metal cores in each particle, the electromagnetic losses can be artificially manipulated at the whole S-band, C-band, X-band, and Ku frequency ranges. The microscopic origins of the controllability of electromagnetic losses are ascribed to the specific matching and interfacial coupling between the magnetic cores and dielectric shells. © 2013 American Chemical Society.

Dou B.,Dalian University of Technology | Song Y.,Dalian University of Technology | Wang C.,Dalian University of Technology | Chen H.,CAS Institute of Engineering Thermophysics | Xu Y.,CAS Institute of Engineering Thermophysics
Renewable and Sustainable Energy Reviews | Year: 2014

The objective of this review is to analyze potential technologies and their baseline performance of producing hydrogen from catalytic steam reforming of biodiesel byproduct glycerol. High oxygen content and high impurity level of biodiesel byproduct glycerol, as well as the complex intermediates and high coking potential in its thermal degradation, make the modeling, design, and operation of glycerol steam reforming a challenge. Thermal decomposition characterization of biodiesel byproduct glycerol was covered, and the recent developments and methods for high-purity hydrogen production from glycerol steam reforming were illustrated. The thermodynamics constraint of water gas shift reaction can be overcome by the sorption-enhanced steam reforming process, which integrated catalytic steam reforming, water gas shift reaction and in-situ CO2 removal at high temperatures in a single stage reactor. The effectiveness of both the enhanced H2 production and the use of CO2 sorbents have been demonstrated and discussed. The technical challenges to achieve a stable high-purity hydrogen production by the sorption-enhanced steam reforming process included extending operation time, selecting suitable sorbents, finding a way for continuous reaction-regeneration of catalyst and sorbent mixture and improving process efficiencies. The continuous sorption-enhanced steam reforming of glycerol was designed by a simultaneous flow concept of catalyst and sorbent for continuous reaction-regeneration using two slow moving-bed reactors for high-purity hydrogen production and CO2 capture, and in this process, catalyst and sorbent were run in nearly fresh state for H2 production. The sorption-enhanced chemical-looping reforming was also demonstrated. The paper discusses some issues and challenges, along with the possible solutions in order to help in efficient production of hydrogen from catalytic steam reforming of biodiesel byproduct glycerol. © 2013 Elsevier Ltd.

Dou B.,Dalian University of Technology | Chen H.,CAS Institute of Engineering Thermophysics
Desalination | Year: 2011

In this study, the adsorption and photocatalytic reduction of toxic mercury(II) from aqueous solutions at different pH values were investigated with the synthesized TiO2 nanoparticles. The synthesized materials were tested and characterized by TEM, XRD and BET methods. The results showed that high purity anatase TiO2 nanoparticles with an average diameter of 9.10nm were produced by the acid catalyzed sol-gel method at 500°C, and the specific surface areas of synthesized TiO2 nanoparticles were in excess of 200m2g-1. The experimental results showed that the removal of mercury(II) in aqueous solutions were increased with an increase of pH in the range of 3.0-7.0, and the conversion of mercury(II) removal was more than 65% by TiO2 nanoparticles after 30min under UV illumination. Kinetics models of the adsorption and photocatalytic reduction were also studied by the experimental measurements. © 2010 Elsevier B.V.

Wang L.,Nanchang Hangkong University | Liu X.,Dalian University of Technology
Information Sciences | Year: 2013

This paper is concerned with the problem of computing the bounds of disturbances for continuous-time Takagi-Sugeno fuzzy model. Two kinds of disturbances are investigated by applying the non-parallel distributed compensation (non-PDC) law, non-quadratic Lyapunov function and Lagrange multiplier method. One is bounded by magnitude, the other is bounded by energy. If the exogenous disturbances are bounded by magnitude, the maximal value of the magnitude under which the closed-loop system can be controlled is obtained by solving an optimization problem. On the other hand, if the disturbances are bounded by energy, except for the maximal bound, some conditions are derived to get two local regions (a smaller and a bigger) such that all the trajectories starting from the smaller region will remain in the bigger one which is required to be contained in a specific compact set (where the original system can be represented as T-S model exactly). In the end, the effectiveness of the proposed results is demonstrated by two examples. © 2013 Elsevier Inc. All rights reserved.

Xu Z.,University of Cambridge | Xu Z.,Ewha Womans University | Xu Z.,Dalian University of Technology | Yoon J.,Ewha Womans University | Spring D.R.,University of Cambridge
Chemical Society Reviews | Year: 2010

In the past decade, fluorescent chemosensors for zinc ion (Zn2+) have attracted great attention because of the biological significance of zinc combined with the simplicity and high sensitivity of fluorescence assays. Chemosensors can be divided into a fluorophore, a spacer and a receptor unit; the receptor is the central processing unit (CPU) of a chemosensor. This tutorial review will classify zinc chemosensors based on receptor types. © The Royal Society of Chemistry 2010.

Chen X.,Ewha Womans University | Zhou Y.,Ewha Womans University | Peng X.,Dalian University of Technology | Yoon J.,Ewha Womans University
Chemical Society Reviews | Year: 2010

Due to the biological importances of thiols, such as cysteine, homocysteine and glutathione, the development of optical probes for thiols has been an active research area in recent few years. This critical review focuses on the fluorescent or colorimetric sensors for thiols according to their unique mechanisms between sensors and thiols, including Michael addition, cyclization with aldehyde, cleavage of sulfonamide and sulfonate ester by thiols, cleavage of selenium-nitrogen bond by thiols, cleavage of disulfide by thiols, metal complexes-oxidation-reduction, metal complexes-displace coordination, nano-particles and others (110 references). © The Royal Society of Chemistry 2010.

Xu Z.,University of Cambridge | Xu Z.,Dalian University of Technology | Yoon J.,Ewha Womans University | Spring D.R.,University of Cambridge
Chemical Communications | Year: 2010

A fluorescent probe was designed and shown to detect Cu2+ ratiometrically and selectively in aqueous solutions based on naphthalimide excimer-monomer switching. © 2010 The Royal Society of Chemistry.

Chen X.,Ewha Womans University | Chen X.,Nanjing University of Technology | Zhou G.,Nanjing University of Technology | Peng X.,Dalian University of Technology | Yoon J.,Ewha Womans University
Chemical Society Reviews | Year: 2012

Polydiacetylenes (PDAs), a family of conjugated polymers, have very unique electrical and optical properties. Upon environmental stimulation, such as by viruses, proteins, DNAs, metal ions, organic molecules etc., the blue PDAs can undergo a colorimetric transition from blue to red, which is accompanied by a fluorescence enhancement. Since the first report on polymerized diacetylene molecules as sensors of influenza virus, the development of efficient sensory systems based on PDAs continues to be of great interest. This tutorial review highlights the recent advances in bio- and chemo-sensors derived from polydiacetylenes. © 2012 The Royal Society of Chemistry.

« $10-Trillion Investment Needed To Avoid Massive Oil Price Spike Says OPEC | Main | IHS: connectivity, infotainment, safety to drive growth in automotive display systems to $18.6B by 2021; > 11% CAGR » Researchers at the Dalian University of Technology have proposed a novel method to control premixed charge compression ignition (PCCI) phasing in internal combustion engines in all load operations. High-pressure air jet controlled compression ignition (JCCI) is based on a compound thermodynamic cycle and is implemented in a hybrid pneumatic engine (HPE) as proposed by Schechter in 1999. The application of HPE is also beneficial to the fuel consumption and emissions because of its several flexible operation modes. A paper on the use of JCCI is published in the ACS journal Energy & Fuels. Premixed charge compression ignition (PCCI) combustion can reduce both NO and PM simultaneously while maintaining high thermal efficiency. In PCCI combustion mode, the air−fuel mixture is well mixed before combustion occurs; formation of NO and PM can be suppressed because of the reduction of rich region in the combustion chamber. However, the control of combustion phasing is one of the crucial issues in determining whether the diesel PCCI engine could be commercialized or not. The hybrid pneumatic engine (HPE) concept, which combines a conventional internal combustion engine with a pneumatic storage system, instead of using an expensive battery in an electric hybrid engine, has become an interesting method to realize both low fuel consumption and emissions. Its flexible operation modes, like air compression mode, air power mode, firing and charging mode, and normal engine firing mode, enable the engine to run in a range of high-efficiency loads all the time. The utilization of compressed air power on engine cool starts and low-load conditions could significantly reduce the overall emissions. High-pressure air JCCI combustion is implemented in HPE engine with the compound thermodynamic cycle of the engine—a cycle with low-compression ratio, high pressure-rise ratio, and high-expansion ratio—reducing the specific requirements of fuel properties. Earlier work showed that the process of high-pressure air jetted into the constant combustion chamber resulted in a rapid increase in mixture temperature and pressure in the local region of the chamber. The maximum temperature rise was more than 150 K—sufficient to allow the mixture at the critical conditions to meet autoignition conditions. Using this approach, the combustion phasing can be controlled directly by the high-pressure air jet. For the current study, the engine was derived from a single-cylinder, naturally aspirated, high-speed direct-injection (HSDI) diesel engine with a displacement of 0.418 L. A major modification was the reduction of the geometric compression ratio from 19 to 12, ensuring that no autoignition occurs in the chamber without any additional heat source. High-pressure air was jetted into the combustion chamber through a check valve, which was added in the central position of the cylinder head to prevent backfire. The team used a 3D CFD model coupled with reduced n-heptane chemical kinetics to study the effects of high-pressure air jet pressure and temperature on combustion characteristics in the high-pressure air JCCI combustion mode. Among their conclusions:

At the 2015 United Nations Climate Change Conference in Paris, 195 countries agreed to investigate and adopt methods to reduce emissions of gases including carbon dioxide. Carbon dioxide is released into the atmosphere in two basic ways: naturally, through plant respiration and decomposition, as well as from human activities, such as deforestation, cement production and energy generation from burning fossil fuels. Song plans to use carbon dioxide as a raw material to create fuels, chemicals and materials that are traditionally produced from petroleum. He's a world leader in this approach, known as carbon dioxide conversion or carbon dioxide utilization, and chairs a committee for the International Conference on Carbon Dioxide Utilization (ICCDU). In Song's laboratory on the University Park campus, he has seen results that indicate carbon dioxide conversion could be the best long-term solution to reduce excess carbon dioxide in the atmosphere. Song's primary goal in his research—and the dream that has fueled more than a decade of his carbon dioxide conversion studies—is to develop a sustainable energy cycle for the future. Part of this involves addressing what he sees as an imbalance in the world's natural global carbon cycle. "Normally, carbon dioxide in the air is absorbed by growing plants through photosynthesis, and plants either are eaten by animals or they die. Matter from decomposing animals and plants is used by microbes for respiration, and this process releases carbon back into the atmosphere, which continues the cycle," says Song, who is a distinguished professor of fuel science. However, the rapid consumption of fossil fuels, which releases carbon dioxide, has offset that balance, he says. "Most of the coal, petroleum, natural gas and other fossil fuels we use today for power originated between 280 and 300 million years ago," Song says. "They are burned in a matter of minutes, which means we're using them up millions of times faster than they were formed. There's no way you can be sustainable in this fashion." Song believes the global carbon cycle balance can be restored by changing how we view carbon dioxide. Instead of looking at it as a pollutant or a waste product, Song sees carbon dioxide as a valuable ingredient for creating fuels, industrial chemicals and other materials. The goal of carbon conversion is to break apart carbon dioxide into its parts—carbon and oxygen molecules—and then use those parts as building blocks for different materials. Song's approach requires three main ingredients: carbon dioxide, a chemical catalyst and hydrogen, which can be created when water molecules are chemically separated using renewable energy, such as through the chemical process of electrolysis. Catalysts are chemicals that influence how carbon and hydrogen molecules fit together, and they play a critical role in what products can be created through carbon conversion. They modify the surface properties, such as surface electron density, of the molecules, which allows the molecules to fit together in new and different ways. For example, it could allow for more carbon or hydrogen atoms to be added to the desired molecule, or it could change the types of bonds between carbon and hydrogen atoms. It's similar to modifying the shape of a puzzle piece so that it can connect to a new puzzle. Every change made at the atomic level affects the end product and how that product functions. To develop new, selective catalysts for carbon dioxide conversion, Song has been working with Xiao Jiang, a postdoctoral scholar in the EMS Energy Institute; Wenjia Wang, Ph.D. student in energy and mineral engineering; Nuttakorn Bore, a visiting Ph.D. student from Chulalongkorn University in Thailand; and collaborating researchers at Dalian University of Technology in China. They have created and tested several new catalysts within the past several years, and have seen promising results. "We've known for many years that you can create hydrocarbons such as propane and ethane using carbon dioxide conversion, but through our work with surface modification and the creation of novel catalysts, we're showing that it's possible to selectively produce valuable chemicals and fuels," says Song. By modifying the surface of the molecules in the recipe, Song has been able to transform carbon dioxide directly in a one-step reaction to ethylene and propylene, among other transformations. These two materials belong to a group of molecules known as olefins and are widely used to manufacture many useful materials: bottles for water and soda, wrinkle-resistant fibers, plastic bags, bottles and films in the food industry and machine parts used in medical devices. The possibilities for materials that can be created through carbon dioxide conversion are seemingly endless, depending on the catalyst used. Iron combined with cobalt is among the catalysts Song's group has used to produce olefins. He has also designed a different catalyst, copper coupled with palladium, to convert carbon dioxide directly in a one-step reaction to methanol, which is widely used in chemicals and fuels. But Song isn't just making new materials—he's also focusing on optimizing the different carbon conversion processes. Additionally, he's investigating the feasibility of incorporating renewable energy sources to provide the extra energy needed for the conversion. "Some of the criticism in the past has been that the carbon dioxide conversion process requires extra energy for hydrogen production, which uses natural gas or coal today, so there's a net loss of energy and the process wouldn't actually be sustainable. But we will use renewable energy for hydrogen production, and in fact researchers at Penn State and elsewhere are investigating the use of renewable energies like solar or wind to generate hydrogen, which can sustain the process," he says. He has been able to increase the efficiency of some of his carbon dioxide conversion processes by 300 percent over the conventional state-of-the-art processes in the past few years, by adjusting catalysts and tweaking his process. Song hopes that the development of new catalysts and the optimization of his carbon dioxide conversion processes will underscore the importance and reliability of carbon dioxide conversion as a method of reducing greenhouse gas emissions and decreasing our dependence on fossil resources. "It has been my dream to develop a sustainable green energy cycle that communities around the world can use, and I think that carbon dioxide conversion provides a promising path forward. It really is a sustainable way to build a new energy cycle," he says. Explore further: Study finds that soil carbon may not be as stable as previously thought

Xu T.,Colorado State University | Xu T.,Dalian University of Technology | Chen E.Y.-X.,Colorado State University
Journal of the American Chemical Society | Year: 2014

The first highly active phosphine (P)/borane (B) Lewis pair polymerization is promoted unexpectedly by P-B adducts. The P and B site cooperativity is essential for achieving effective polymerization, as shown by this study examining the reactivity of a library of P/B Lewis pairs toward polymerization of a renewable acrylic monomer. © 2014 American Chemical Society.

Majumdar P.,Sambalpur University | Majumdar P.,Dalian University of Technology | Pati A.,Sambalpur University | Pati A.,KIIT University | And 3 more authors.
Chemical Reviews | Year: 2014

A study was conducted to provide practical guidance for synthetic chemists on the synthesis of oxygen-, nitrogen-, and sulfur-containing heterocyclic rings. Reaction of benz(g)indole dicarboxylate 5 with hydrazine hydrate in refluxing ethanol and a catalytic amount of pyridine chemoselectively produced only 63% of benz(g)indole monocarbohydrazide 7 instead of the expected dicarbohydrazide 6 wherein the C3carboethoxy group remained unchanged toward nucleophile hydrazine hydrate. The resistance of the heterocycles formed, starting with five- and six-membered rings. These systematic collections in the study expanded the ample possibilities to the synthetic methods accessed by the chemistry for synthesis of heterocyclic compounds and would be useful to pick the route for further research.

Liu C.,Nanotek Instruments, Inc. | Liu C.,Dalian University of Technology | Yu Z.,Angstron Materials, Inc | Neff D.,Nanotek Instruments, Inc. | And 2 more authors.
Nano Letters | Year: 2010

A supercapacitor with graphene-based electrodes was found to exhibit a specific energy density of 85.6 Wh/kg at room temperature and 136 Wh/kg at 80 °C (all based on the total electrode weight), measured at a current density of 1 A/g. These energy density values are comparable to that of the Ni metal hydride battery, but the supercapacitor can be charged or discharged in seconds or minutes. The key to success was the ability to make full utilization of the highest intrinsic surface capacitance and specific surface area of single-layer graphene by preparing curved graphene sheets that will not restack face-to-face. The curved morphology enables the formation of mesopores accessible to and wettable by environmentally benign ionic liquids capable of operating at a voltage >4 V. © 2010 American Chemical Society.

Wu M.,Hebei Normal University | Ma T.,Dalian University of Technology | Ma T.,Kyushu Institute of Technology
Journal of Physical Chemistry C | Year: 2014

To realize long-term developments and practical application of the dye-sensitized solar cells (DSCs) requires a robust increase of the power conversion efficiency (PCE) and a significant decrease of the production cost. Fortunately, a new record PCE value of 12.3% was achieved by using cobalt-based redox couples combined with organic dye. Evidently, dye design is the key path to improve the PCE, while developing low cost counter electrode (CE) catalysts is one of the promising paths to reduce the production cost of DSCs by replacing the expensive Pt CE. In this article, we review the recent progress of CE catalysts involving Pt, carbon materials, inorganic materials, multiple compounds, polymers, and composites. We discuss the advantages and disadvantages of each catalyst and put forward ideas for designing new CE catalysts in future research for DSCs and other application fields. © 2014 American Chemical Society.

Jin F.,Dalian University of Technology | Guo X.,Dalian University of Technology | Gao H.,Brown University
Journal of the Mechanics and Physics of Solids | Year: 2013

A cohesive zone model of axisymmetric adhesive contact between a rigid sphere and a power-law graded elastic half-space is established by extending the double-Hertz model of Greenwood and Johnson (1998). Closed-form solutions are obtained analytically for the surface stress, deformation fields and equilibrium relations among applied load, indentation depth, inner and outer radii of the cohesive zone, which include the corresponding solutions for homogeneous isotropic materials and the Gibson solid as special cases. These solutions provide a continuous transition between JKR and DMT type contact models through a generalized Tabor parameter μ. Our analysis reveals that the magnitude of the pull-off force ranges from (3 + κ)πRΔγ/2 to 2πRΔγ, where κ, R and Δγ denote the gradient exponent of the elastic modulus for the half-space, the radius of the sphere and the work of adhesion, respectively. Interestingly, the pull-off force for the Gibson solid is found to be identically equal to 2πRΔγ, independent of the corresponding Tabor parameter. The obtained analytical solutions are validated with finite element simulations. © 2013 Elsevier Ltd. All rights reserved.

Guo X.,Dalian University of Technology | Jin F.,Dalian University of Technology | Gao H.,Brown University
International Journal of Solids and Structures | Year: 2011

In previous work about axisymmetric adhesive contact on power-law graded elastic materials, the contact interface was often assumed to be frictionless, which is, however, not always the case in practical applications. In order to elucidate the effect of friction and the coupling between normal and tangential deformations, in the present paper, the problem of a rigid punch with a parabolic shape in non-slipping adhesive contact with a power-law graded half-space is studied analytically via singular integral equation method. A series of closed-form analytical solutions, which include the frictionless and homogeneous solutions as special cases, are obtained. Our results show that, compared with the frictionless case, the interfacial friction tends to reduce the contact area and the indentation depth during adhesion. The magnitude of the coupling effect depends on both the Poisson ratio and the gradient exponent of the half-space. This effect vanishes for homogeneous incompressible as well as for linearly graded materials but becomes significant for auxetic materials with negative Poisson's ratio. Furthermore, influence of mode mixity on the adhesive behavior of power-law graded materials, which was seldom touched in literature, is discussed in details. © 2011 Elsevier Ltd. All rights reserved.

Liu T.,Dalian University of Technology | Jia C.,Shenyang University
Journal of Theoretical Biology | Year: 2010

One major problem with the existing algorithm for the prediction of protein structural classes is low accuracies for proteins from α/Β and α+Β classes. In this study, three novel features were rationally designed to model the differences between proteins from these two classes. In combination with other rational designed features, an 11-dimensional vector prediction method was proposed. By means of this method, the overall prediction accuracy based on 25PDB dataset was 1.5% higher than the previous best-performing method, MODAS. Furthermore, the prediction accuracy for proteins from α+Β class based on 25PDB dataset was 5% higher than the previous best-performing method, SCPRED. The prediction accuracies obtained with the D675 and FC699 datasets were also improved. © 2010 Elsevier Ltd.

Li R.,State Key Laboratory of Structural Analysis for Industrial Equipment | Zhong Y.,Dalian University of Technology | Li M.,State Key Laboratory of Structural Analysis for Industrial Equipment
Proceedings of the Royal Society A: Mathematical, Physical and Engineering Sciences | Year: 2013

Analytic bending solutions of free rectangular thin plates resting on elastic foundations, based on the Winkler model, are obtained by a new symplectic superposition method. The proposed method offers a rational elegant approach to solve the problem analytically, which was believed to be difficult to attain. By way of a rigorous but simple derivation, the governing differential equations for rectangular thin plates on elastic foundations are transferred into Hamilton canonical equations. The symplectic geometry method is then introduced to obtain analytic solutions of the plates with all edges slidingly supported, followed by the application of superposition, which yields the resultant solutions of the plates with all edges free on elastic foundations. The proposed method is capable of solving plates on elastic foundations with any other combinations of boundary conditions. Comprehensive numerical results validate the solutions by comparison with those obtained by the finite element method. Copyright © The Royal Society 2013.

Yang Z.,Korea University | Yang Z.,Qingdao University of Science and Technology | Cao J.,Dalian University of Technology | He Y.,Korea University | And 5 more authors.
Chemical Society Reviews | Year: 2014

Environment-related parameters, including viscosity, polarity, temperature, hypoxia, and pH, play pivotal roles in controlling the physical or chemical behaviors of local molecules. In particular, in a biological environment, such factors predominantly determine the biological properties of the local environment or reflect corresponding status alterations. Abnormal changes in these factors would cause cellular malfunction or become a hallmark of the occurrence of severe diseases. Therefore, in recent years, they have increasingly attracted research interest from the fields of chemistry and biological chemistry. With the emergence of fluorescence sensing and imaging technology, several fluorescent chemosensors have been designed to respond to such parameters and to further map their distributions and variations in vitro/in vivo. In this work, we have reviewed a number of various environment-responsive chemosensors related to fluorescent recognition of viscosity, polarity, temperature, hypoxia, and pH that have been reported thus far. © 2014 The Royal Society of Chemistry.

Chen B.-B.,Dalian University of Technology | Shi C.,Dalian University of Technology | Crocker M.,University of Kentucky | Wang Y.,Dalian University of Technology | Zhu A.-M.,Dalian University of Technology
Applied Catalysis B: Environmental | Year: 2013

Two kinds of Au/CeO2, prepared by deposition-precipitation (DP) using urea (U) or NaOH (N) as precipitants were investigated as catalysts for HCHO oxidation. H2-TPR and XPS techniques were used to characterize the Au/CeO2 samples. Due to the generation of increased amounts of active surface oxygen species resulting from the strong Au-CeO2 interaction, the Au/CeO2 (DPU) catalyst showed higher activity than the DPN catalyst, achieving 100% conversion of HCHO into CO2 and H2O at room temperature, even in the presence of water and at high GHSV (143,000h-1); moreover, the conversion was stable for at least 60h. The reaction mechanism and the rate limiting steps for HCHO oxidation over the Au/CeO2 catalysts were identified by means of in situ DRIFTS studies. The influence of oxygen and water on the formation and consumption of the formate reaction intermediates was also investigated. Results suggest that Au/CeO2 (DPU) is a promising catalyst for HCHO removal under real world conditions. © 2012 Elsevier B.V.

Lin K.,Dalian University of Technology | Chen M.,Huazhong University of Science and Technology | Zeadally S.,University of the District of Columbia | Rodrigues J.J.P.C.,University of Beira Interior
Future Generation Computer Systems | Year: 2012

For Wireless Sensor Networks (WSNs), an unbalanced energy consumption will decrease the lifetime of network. In this paper, we leverage mobile agent technology to investigate the problem of how to balance the energy consumption during data collection in WSNs. We first demonstrate that for a sensor network with uniform node distribution and constant data reporting, balancing the energy of the whole network cannot be realized when the distribution of data among sensor nodes is unbalanced. We design a method to mitigate the uneven energy dissipation problem by controlling the mobility of agents, which is achieved by an energy prediction strategy to find their positions. Finally, we propose energy balancing cluster routing based on a mobile agent (EBMA) for WSNs. To obtain better performance, the cluster structure is formed based on cellular topology taking into consideration the energy balancing of inter-cluster and intra-cluster environments. Extensive simulation experiments are carried out to evaluate EBMA with several performance criteria. Our simulation results show that EBMA can effectively balance energy consumption and perform high efficiency in large-scale network deployment. © 2011 Elsevier B.V. All rights reserved.

Guo F.,Dalian University of Technology | Guo F.,CAS Xishuangbanna Tropical Botanical Garden | Xiu Z.-L.,Dalian University of Technology | Liang Z.-X.,Dalian University of Technology
Applied Energy | Year: 2012

Biodiesel was produced from acidified soybean soapstocks by using lignin-derived carbonaceous catalyst (LCC). LCC was a solid acidic catalyst prepared by direct sulfonation of residual lignin from Xanthoceras sorbifolia Bunge hulls. The textural properties of the catalyst were characterized by 13C MAS NMR, X-ray diffraction, FT-IR, elemental analysis and BET surface area measurement. When 7wt.% of LCC was used in the esterification, the maximum free fatty acids (FFAs) conversion (above 97%) could be achieved at a molar ratio of methanol/oil of 1:9 and a reaction temperature of 70°C for 5h. A comparison of catalytic activity between sulfuric acid and LCC revealed that LCC performed 3.5 times higher activity than sulfuric acid with the equivalent active group (SO3H). Additionally, LCC could be reused at least three times with high FFAs conversion (>80%). © 2012 Elsevier Ltd.

Fan R.-J.,Dalian University of Technology | Sun Q.,Dalian University of Technology | Zhang L.,Dalian University of Technology | Zhang Y.,Dalian Medical University | Lu A.-H.,Dalian University of Technology
Carbon | Year: 2014

Photoluminescent carbon dots (C-dots) were prepared directly by a simple hydrothermal treatment using polyethylene glycol with different molar weight (400-6000 g mol-1) as the sole carbon source. The synthesized C-dots with tunable diameters of 2-4 nm exhibit excitation-dependent photoluminescent behavior. In contrast to previous methods, neither strong acid treatment nor further surface modification is necessary for this one-step process. The C-dots with well-defined surface chemistry and properties were well-dispersed in aqueous media and showed high photostability indicating they are suitable for use in different pH and NaCl aqueous solutions. The C-dots possessed low cytotoxicity, good photostability and can enter the cancer cells, making them suitable candidates for two-photon cellular imaging and labelling. © 2014 Elsevier Ltd. All rights reserved.

Agency: European Commission | Branch: FP7 | Program: CP | Phase: ENERGY.2012.5.2.2 | Award Amount: 3.99M | Year: 2013

The CO2QUEST proposal addresses the fundamentally important issues regarding the impact of the typical impurities in the gas or dense phase CO2 stream captured from fossil fuel power plants on its safe and economic transportation and storage. The proposed work programme will focus on the development of state-of-the art mathematical models backed by laboratory and industrial-scale experimentation utilising unique EC funded test facilities to perform a comprehensive techno-economic, risk-based assessment of the impact of the CO2 stream impurities on phase behaviour and chemical reactions, and on pipeline and storage site integrities. The above involves the determination of the important CO2 mixtures that have the most profound impact on the pipeline pressure drop, compressor power requirements, pipeline propensity to ductile and brittle facture propagation, corrosion of the pipeline and wellbore materials, geochemical interactions within the wellbore and storage site, and the ensuing health and environmental hazards. Based on a cost/benefit analysis and whole system approach, the results will in turn be used to provide recommendations for tolerance levels, mixing protocols and control measures for pipeline networks and storage infrastructure. CO2QUEST addresses all the main themes of this Call in several ways. It involves the active participation of key players from the Carbon Capture Sequestration Forum, in particular China (partner), Canada and USA (Strategic Committee Members), and the worlds leading steel producer representing a CO2 intensive industry. CO2QUEST involves the participation of leading academics with directly relevant fundamental and pre-normative research track records. A main focus of attention will be maximising the projects impact by ensuring that its results are effectively exploited and actively disseminated, in particular, supporting the development of relevant design and operation standards for CCS infrastructure.

Liu W.,Dalian University of Technology | Chen S.-E.,University of North Carolina at Charlotte
Structural Control and Health Monitoring | Year: 2013

Terrestrial 3D Light Detection and Ranging (LiDar) scanner has been suggested as a remote sensing technique for existing and newly constructed bridges. Using high resolution laser, 3D LiDar can populate a surficial area with millions of position data points. Bridge problems can benefit from LiDar scan, and current studies have found potential applications including damage detection, bridge clearance, and static deflection measurement. The technique is useful when accurate measurement of bridge geometry cannot be achieved by traditional survey technique, especially when site topography is prohibitive. However, resolution is still one of the main factors that limit the application of LiDar technology for advanced bridge monitoring. This paper discusses the reliability issues of such technique as well as the LiDar based bridge condition evaluation methodologies. Several experimental results are presented to establish the sensitivities for different assessments. Copyright © 2013 John Wiley & Sons, Ltd.

Gao B.,Dalian University of Technology | Liu L.,Dalian University of Technology | Liu J.,Dalian University of Technology | Yang F.,Dalian University of Technology
Applied Catalysis B: Environmental | Year: 2013

Fe doped ZnIn2S4 catalyst was prepared and tested for photocatalytic degradation of 2,4,6-tribromophenol (2,4,6-TBP), it was more efficient in debromination and total organic carbon (TOC) removal, compared with TiO2 (P25) and ZnIn2S4. The preparation of Fe-ZnIn2S4 involved a facile hydrothermal ZnIn2S4 synthesis process at low temperature and without templates, followed by chemical reductive deposition of Fe. The catalysts were characterized using scanning electron microscopy (SEM) equipped with an X-ray energy dispersive spectroscopy (EDS), TEM and HRTEM, FT-IR spectra, X-ray diffraction (XRD) and UV-vis diffuse reflectance spectra. The band gaps of ZnIn2S4 and Fe-ZnIn2S4 calculated from the onset of the absorption edges were 2.12eV and 2.05eV, respectively. The calculated pseudo-first-order constants (Kr) were in the order of TiO2 (0.022min-1)<0.5wt% Fe-TiO2 (0.0369min-1)

By using a 15m thick, well-dated basic sill as an example, this study presents an investigation on the effect of errors in thermophysical parameters of igneous intrusions and over-simplification in heat transfer equations as well as uncertainties in pore-water volatilization and intrusion mechanisms of magma on quantitative evaluation of thermal alteration in contact metamorphic aureoles based on heat transfer models and the EASY%Ro model. Our results indicate: 1) Using an under-estimated and temperature-independent specific heat (e.g. ~800Jkg -1°C -1) of igneous intrusions instead of the temperature-dependent specific heat can cause the maximum deviation of 68°C in peak temperature and of 1.3% in vitrinite reflectance, whereas such deviations (less than 26°C and 0.1%) are small enough to be ignored for the model using a high, invariable specific heat (e.g. ~1200Jkg -1°C -1) of igneous intrusions. The specific heat of igneous intrusions is likely a more notable error source in causing model deviations compared to the intrusion temperature and the latent crystallization heat of melted magma, if the latent crystallization heat is allowed for; 2) the effect of the uncertainty in whether pore water volatilized during cooling of intrusive magma on the model prediction can be as notable as that of the use of an under-estimated specific heat. The over-simplification in heat transfer equations (i.e. the variation of thermal conductivity with spatial location is not used) results in an obvious underestimation of the thermal effect of igneous intrusions on host rocks. The model deviation caused by this type of error may be far beyond that caused by the errors in thermophysical parameters of igneous intrusions or the uncertainty in pore-water volatilization; 3) the model deviations due to the errors in the thermophysical parameters and the uncertainty in pore-water volatilization can be large enough to disturb the estimation of the intrusion mechanism based on heat transfer models. By comparing the vitrinite reflectance predicted by different heat transfer models with the measured one, the results from more than one type of model can be found to match well with the observation. Only the model of the finite-time intrusion mechanism can be reasonably regarded as representing natural conditions. It is not fully reliable to validate the availability of the used heat transfer models only by observing whether the model results match with measured geothermometers due to the effect of these uncertainties, errors and over-simplification. More careful model specification and parameter estimation are required in the future use of heat transfer models of igneous intrusions. © 2012 Elsevier B.V.

Zhang S.,Dalian University of Technology | Zhang B.,Dalian University of Technology | Zhao G.,Dalian University of Technology | Jian X.,Dalian University of Technology
Journal of Materials Chemistry A | Year: 2014

A series of heterocyclic poly(aryl ether ketone)s containing 3,5-dimethyl phthalazinone moieties were synthesized via the copolymerization of 4-(3,5-dimethyl-4-hydroxyphenyl)(2H)-phthalazin-1-one, 4-(4-hydroxyphenyl)(2H)- phthalazin-1-one and 4,4′-difluorobenzophenone. The resulting polymers were brominated with N-bromosuccinimide as the bromination reagent. Brominated poly(phthalazinone ether ketone) (BPPEK) with a degree of substitution in the range of 0.48-0.82 was obtained. Quaternized poly(phthalazinone ether ketone) anion exchange membranes (QBPPEK) were prepared from BPPEK membranes with trimethylamine as the amination reagent. Ion exchange capacity (IEC) values of the QBPPEK membranes were in the range of 0.82-1.53 mmol g-1. Compared with Nafion117 membrane, QBPPEK membranes showed much lower vanadium permeability. Coulombic efficiencies of the vanadium redox flow battery (VRB) with QBPPEK membranes were higher than that with the Nafion117 membrane. The energy efficiency of the VRB increased with an increase in the IEC of the QBPPEK membrane. The energy efficiency of the VRB cell with the QBPPEK membrane having an IEC of 1.53 mmol g-1 was 88%, which was higher than that of the cell with the Nafion117 membrane. During 100 charge-discharge cycles, the QBPPEK anion exchange membrane showed a stable performance. © 2014 The Royal Society of Chemistry.

Zhao Z.,Dalian University of Technology | Dai Y.,Dalian University of Technology
Journal of Materials Chemistry A | Year: 2014

Nanodiamond/carbon nitride (ND/CNx) nanoarchitectures with a stacked carbon nitride layer on nanodiamond have been successfully fabricated through a facile pyrolysis approach of pristine nanodiamond and melamine at temperatures of 650, 700, and 750 °C, which challenges the long-held axiom that a CNx layer can only be formed at condensation temperatures of less than 600 °C and it decomposes and inserts into the carbon matrix at temperatures higher than 600 °C. The structure and surface chemical properties of ND/CNx nanomaterials are strongly dependent on pyrolysis temperature and the mass ratio of nanodiamond to melamine. The optimized ND/CNx hybrid carbon nanoarchitecture exhibits synergistically enhanced catalytic performance for the direct dehydrogenation of ethylbenzene to styrene under oxidant- and steam-free conditions. A steady-state styrene rate of 4.0 mmol g-1 h -1 with 99% selectivity for the developed catalyst was achieved, whereas steady-state styrene rates of only 2.7 and 2.0 mmol g-1 h-1 with 95% and 96% selectivity were obtained for pristine nanodiamond and mesoporous carbon nitride, respectively, under the same reaction conditions. This was attributed to the synergistic effect between the nanodiamond and carbon nitride of the hybrid material with an appropriate amount of CNx layer and surface chemical properties. The developed ND/CNx carbon hybrid nanoarchitecture demonstrated 1.48 and 4.15 times the steady-state styrene rate of the established ND and the industrially used K-Fe catalyst, respectively, which allows it to be a potential catalyst for future industrial applications for styrene production through the metal-free dehydrogenation of ethylbenzene under oxidant- and steam-free conditions. This work also presents a facile method to synthesize new carbon nitride layer-containing hybrid nanocarbon materials for diverse applications with excellent properties. This journal is © the Partner Organisations 2014.

Fu X.,Dalian University of Technology | Zhu Q.,Dalian University of Technology | Sarkis J.,Clark University
International Journal of Production Economics | Year: 2012

Green supplier development has become necessary as organizations increasingly compete on environmental supply chain capabilities. However, formal modeling tools to aid managers in evaluating green supplier development programs (GSDPs) are virtually non-existent. This paper introduces a formal structured managerial approach for organizations to help evaluate the influence relationships amongst GSDPs. Utilizing GSDP categorizations we acquire multi-functional managerial inputs within a telecommunication systems provider to evaluate the GSDPs. The managerial inputs are evaluated using a formalized grey-based DEMATEL methodology. Managerial and research implications of the proposed study and application, limitations and future research directions are also detailed. © 2011 Elsevier B.V. All rights reserved.

Lin D.,Dalian University of Technology | Lin D.,University of Sichuan | Wang X.,Dalian University of Technology
Neurocomputing | Year: 2011

This paper proposes a self-organizing adaptive fuzzy neural control (SAFNC) for the synchronization of uncertain chaotic systems with random-varying parameters. The proposed SAFNC system is composed of a computation controller and a robust controller. The computation controller containing a self-organizing fuzzy neural network (SOFNN) identifier is the principle controller. The SOFNN identifier is used to online estimate the compound uncertainties with the structure and parameter learning phases of fuzzy neural network (FNN), simultaneously. The structure-learning phase consists of the growing of membership functions, the splitting of fuzzy rules and the pruning of fuzzy rules, and thus the SOFNN identifier can avoid the time-consuming trial-and-error tuning procedure for determining the network structure of fuzzy neural network. The robust controller is used to attenuate the effects of the approximation error so that the synchronization of chaotic systems is achieved. All the parameter learning algorithms are derived based on the Lyapunov stability theorem to ensure network convergence as well as stable synchronization performance. To demonstrate the effectiveness of the proposed method, simulation results are illustrated in this paper. © 2011 Elsevier B.V.

Zhang Y.,Dalian University of Technology | Wang X.,Dalian University of Technology
Nonlinear Analysis: Real World Applications | Year: 2012

In this paper, a fractal image compression coding scheme based on wavelet transform with diamond search is proposed. The goal is to offer fast positioning. According to search pattern and search path of diamond search, the proposed scheme just needs to search in the domain blocks in the fixed place around the range blocks. Our proposed method has benefits in reducing the search time and enhancing the coding speed compared with other image compression techniques. © 2011 Elsevier Ltd. All rights reserved.

Yin Z.,Dalian University of Technology | Cheng E.,Dalian University of Technology | Zou H.,Dalian University of Technology
Lab on a Chip - Miniaturisation for Chemistry and Biology | Year: 2014

Nanofluidic devices with micro and nanostructures are becoming increasingly important for biological and chemical applications. However, the majority of the present fabrication methods suffer from a low pattern transfer quality during the simultaneous embossing of the microscale and nanoscale patterns into a thermoplastic polymer due to insufficient polymer flow. In this work, a novel hybrid patterning technique, integrating hot embossing and inverse ultraviolet (UV) photolithography, is developed to fabricate micro and nanochannels with a high replication precision of the SU-8 layer. The influence of embossing temperature and time on the replication precision was investigated. The effect of UV lithography parameters on the micro and nanochannel pattern was analyzed. To improve the SU-8 bonding strength, the influence of the O2 plasma treatment parameters on the water contact angles of the exposed and unexposed SU-8 layer were studied. A complete SU-8 nanofluidic chip with 130 nm wide and 150 nm deep nanochannels was successfully fabricated with a replication precision of 99.5%. Compared with most of the current processing methods, this fabrication technique has great potential due to its low cost and high pattern transfer quality of the SU-8 micro and nanochannels. This journal is © the Partner Organisations 2014.

Yu Q.,Dalian University of Technology | An L.,Dalian University of Technology | Li W.,Dalian University of Technology
Plant Cell Reports | Year: 2014

The calcineurin B-like protein-CBL-interacting protein kinase (CBL-CIPK) signaling pathway in plants is a Ca2+-related pathway that responds strongly to both abiotic and biotic environmental stimuli. The CBL-CIPK system shows variety, specificity, and complexity in response to different stresses, and the CBL-CIPK signaling pathway is regulated by complex mechanisms in plant cells. As a plant-specific Ca2+ sensor relaying pathway, the CBL-CIPK pathway has some crosstalk with other signaling pathways. In addition, research has shown that there is crosstalk between the CBL-CIPK pathway and the low-K+ response pathway, the ABA signaling pathway, the nitrate sensing and signaling pathway, and others. In this paper, we summarize and review research discoveries on the CBL-CIPK network. We focus on the different modification and regulation mechanisms (phosphorylation and dephosphorylation, dual lipid modification) of the CBL-CIPK network, the expression patterns and functions of CBL-CIPK network genes, the responses of this network to abiotic stresses, and its crosstalk with other signaling pathways. We also discuss the technical research methods used to analyze the CBL-CIPK network and some of its newly discovered functions in plants. © 2013 Springer-Verlag Berlin Heidelberg.

Wang X.,Dalian University of Technology | Teng L.,Dalian University of Technology
Nonlinear Dynamics | Year: 2012

In this paper, the CML-based spatiotemporal chaos system is used for image blocks encryption, which gets higher security. The basic idea is to divide the image into blocks, and then use the block numbers as the spatial parameter of CML to iterate the chaos system. Each lattice generates a chaos sequence, and the number of chaos sequence values is equal to the pixels number of each block. The chaos sequences and the former block plaintext codecide the substitution and diffusion of each block. Simulation results show that the performance and security of the proposed encryption system can encrypt the image effectively and resist various typical attacks. © 2011 Springer Science+Business Media B.V.

Zhu Q.,Dalian University of Technology | Sarkis J.,Clark University | Lai K.-H.,Hong Kong Polytechnic University
International Journal of Production Research | Year: 2012

Environmental pressures have caused green supply chain management (GSCM) to emerge as an important corporate environmental strategy for manufacturing enterprises. For manufacturers to fully realise the performance potentials of GSCM, they need to integrate internal GSCM practices emphasising functional coordination with external GSCM practices such as cooperation with suppliers and customers in the implementation. Using coordination theory, this article examines three models used to evaluate the mediation relationships between the external and internal practices of GSCM with respect to environmental, economic, and operational performance. We posit that the strategic stance of manufacturing enterprises in improving their overall performance and competitive position requires a joint coordination of internal and external GSCM practices. Survey data collected from 396 Chinese manufacturing enterprises are used to validate our arguments by testing the mediation effects of two categories of GSCM practices. Our empirical results show support for the mediation effects, which indicates the importance for manufacturers to coordinate between the internal and external aspects of implementing GSCM practices to reap the performance benefits. Coordinating internal and external GSCM practices to seek performance improvements is an important aspect of the manufacturing operations strategy. The dynamics of implementing GSCM practices and the performance contingencies are worthwhile topics to pursue in future research. © 2012 Copyright Taylor and Francis Group, LLC.

Lin D.,University of Sichuan | Wang X.,Dalian University of Technology | Yao Y.,University of Sichuan
Nonlinear Dynamics | Year: 2012

The contribution of this work is to study the control of unknown chaotic systems with input saturation, and the backstepping-based an adaptive fuzzy neural controller (AFNC) is proposed. In many practical dynamic systems, physical input saturation on hardware dictates that the magnitude of the control signal is always constrained. Saturation is a potential problem for actuators of control systems. It often severely limits system performance, giving rise to undesirable inaccuracy or leading instability. To deal with saturation, we construct a new system with the same order as that of the plant. With the error between the control input and saturation input as the input of the constructed system, a number of signals are generated to compensate the effect of saturation. Finally, simulation results show that the AFNC can achieve favorable tracking performances. © 2011 Springer Science+Business Media B.V.

Wang Z.-T.,Dalian University of Technology
Shanghai Ligong Daxue Xuebao/Journal of University of Shanghai for Science and Technology | Year: 2011

In this paper, the concept of hypernetwork based on hypergraph suggested by C. Berge as another kind of supernetwork is introduced. The main feature of hypernetwork is the edge in hypergraph can be connected to more than one nodes. For the investigation of some complex network like telecommunication network, knowledge network, social network, this unique feature may offer more advantages.

Wang X.,Dalian University of Technology | Zhang X.,Dalian University of Technology | Ma C.,Dalian University of Technology
Nonlinear Dynamics | Year: 2012

This paper is devoted to study the problem of modified projective synchronization of fractional-order chaotic system. Base on the stability theorems of fractional-order linear system, active sliding mode controller is proposed to synchronize two different fractional-order systems. Moreover, the controller is robust to the bounded noise. Numerical simulations are provided to show the effectiveness of the analytical results. © 2011 Springer Science+Business Media B.V.

Xu H.,Dalian University of Technology | Zheng M.,Dalian Jiaotong University
Journal of Transportation Engineering | Year: 2012

Curb bus-only lanes and median bus-only lanes are two commonly used types of the on-street running ways of bus rapid transit (BRT) systems. Transit signal priority (TSP) has proven viable in improving transit schedule adherence and in expediting transit service and is recognized as a key element of BRT systems. From a TSP designer's point of view, it provides a systematic analysis of the impact of bus-only lanes location on the development and performance of the logic rule-based bus rapid transit signal priority (BRTSP). As an emerging active TSP for use at isolated signalized intersections, BRTSP is centered on five categories of logic rules and can fully accommodate the variety of phase scheme. Green extension, early green, and phase insertion can be provided to prioritized vehicles within specific priority windows. The signal operations on bus-only lanes and general-purpose lanes are influenced by prioritized vehicle arrivals and departures and general traffic demands that are detected. Compared with curb bus-only lanes arrangement, median bus-only lanes arrangement imposes more restrictions on the establishment of phase combinations and phase sequences, resulting in less flexibility in assigning right-of-way at an intersection level. Among the components of BRTSP, the bus-only lanes location influences the first minimum green time calculation for vehicle phases, the walk interval calculation for pedestrian phases, the definition of priority windows, the design of logic rules, and the placement of prioritized vehicle detectors. The results of simulation experiments conducted by VISSIM under heavy load scenarios indicated the following: (1) no matter the bus-only lanes location, the phase sequence with all the through-vehicle phases defined as the initial phase had the potential to better moderate the negative effect of signal priority treatments on general traffic and pedestrians; (2) insufficient evidence could not prove that median bus-only lanes arrangement had an overwhelming advantage over curb bus-only lanes arrangement in reducing the delays of prioritized vehicles at traffic signals and vice versa; instead, more attention should be paid to general traffic and pedestrians performance when arranging and managing the bus-only lanes; and (3) curb bus-only lanes arrangement appeared to have an advantage over median bus-only lanes arrangement in improving overall intersection performance if green extension and early green were provided to TSP-enabled intersections. To keep general traffic and pedestrians performance from severely deteriorating, phase insertion service, if desired (in addition to green extension and early green), should be provided only to intersections with median bus-only lanes in a conditional manner. © 2012 American Society of Civil Engineers.

Kang Z.,Dalian University of Technology | Wang Y.,Dalian University of Technology
International Journal for Numerical Methods in Engineering | Year: 2012

A method for topology optimization of continuum structures based on nodal density variables and density field mapping technique is investigated. The original discrete-valued topology optimization problem is stated as an optimization problem with continuous design variables by introducing a material density field into the design domain. With the use of the Shepard family of interpolants, this density field is mapped onto the design space defined by a finite number of nodal density variables. The employed interpolation scheme has an explicit form and satisfies range-restricted properties that makes it applicable for physically meaningful density interpolation. Its ability to resolve more complex spatial distribution of the material density within an individual element, as compared with the conventional elementwise design variable approach, actually provides certain regularization to the topology optimization problem. Numerical examples demonstrate the validity and applicability of the proposed formulation and numerical techniques. © 2011 John Wiley & Sons, Ltd..

Yang M.-H.,Xinyang Normal University | Han Z.-Q.,Dalian University of Technology
Nonlinear Analysis: Real World Applications | Year: 2012

In this paper, we study the existence and multiplicity results for the nonlinear SchrödingerPoisson systems -Δu+V(x)u+K(x)φ(x)u=f(x,u), in R 3,-Δφ=K(x) u2,in R 3. Under certain assumptions on V, K and f, we obtain at least one nontrivial solution for (*) without assuming the Ambrosetti and Rabinowitz condition by using the mountain pass theorem, and obtain infinitely many high energy solutions when f(x,·) is odd by using the fountain theorem. © 2011 Elsevier Ltd. All rights reserved.

Li J.-B.,Dalian University of Technology | Luan Y.-S.,Dalian University of Technology | Liu Z.,Dalian University of Technology
Physiologia Plantarum | Year: 2015

WRKY transcription factors are key regulatory components of plant responses to biotic and abiotic stresses. SpWRKY1, a pathogen-induced WRKY gene, was isolated from tomato (Solanum pimpinellifolium L3708) using in silico cloning and reverse transcriptase-polymerase chain reaction (RT-PCR) methods. SpWRKY1 expression was significantly induced following oomycete pathogen infection and treatment with salt, drought, salicylic acid (SA), methyl jasmonate (MeJA) and abscisic acid (ABA). Overexpression of SpWRKY1 in tobacco conferred greater resistance to Phytophthora nicotianae infection, as evidenced by lower malondialdehyde (MDA) content; relative electrolyte leakage (REL); higher chlorophyll content; and higher peroxidase (POD, EC, superoxide dismutase (SOD, EC and phenylalanine ammonia-lyase (PAL, EC activities. This resistance was also coupled with enhanced expression of SA- and JA-associated genes (NtPR1, NtPR2, NtPR4, NtPR5 and NtPDF1.2), as well as of various defense-related genes (NtPOD, NtSOD and NtPAL). In addition, transgenic tobacco plants also displayed an enhanced tolerance to salt and drought stresses, mainly demonstrated by the transgenic lines exhibiting lower accumulation of MDA content and higher POD (EC, SOD (EC activities, chlorophyll content, photosynthetic rate and stomatal conductance, accompanied by enhanced expression of defense-related genes (NtPOD, NtSOD, NtLEA5, NtP5CS and NtNCED1) under salt and drought stresses. Overall, these findings suggest that SpWRKY1 acts as a positive regulator involved in tobacco defense responses to biotic and abiotic stresses. © 2015 Scandinavian Plant Physiology Society.

Dou B.,Dalian University of Technology | Song Y.,Dalian University of Technology
International Journal of Hydrogen Energy | Year: 2010

Hydrogen production from steam reforming of glycerol in a fluidized bed reactor has been simulated using a CFD method by an additional transport equation with a kinetic term. The Eulerian-Eulerian two-fluid approach was adopted to simulate hydrodynamics of fluidization, and chemical reactions were modelled by laminar finite-rate model. The bed expansion and pressure drop were predicted for different inlet gas velocities. The results showed that the flow system exhibited a more heterogeneous structure, and the core-annulus structure of gas-solid flow led to back-mixing and internal circulation behaviour, and thus gave a poor velocity distribution. This suggests the bed should be agitated to maintain satisfactory fluidizing conditions. Glycerol conversion and H 2 production were decreased with increasing inlet gas velocity. The increase in the value of steam to carbon molar ratio increases the conversion of glycerol and H 2 selectivity. H 2 concentrations in the bed were uneven and increased downstream and high concentrations of H 2 production were also found on walls. The model demonstrated a relationship between hydrodynamics and hydrogen production, implying that the residence time and steam to carbon molar ratio are important parameters. The CFD simulation will provide helpful data to design and operate a bench scale catalytic fluidized bed reactor. © 2010 Professor T. Nejat Veziroglu. Published by Elsevier Ltd. All rights reserved.

Shen C.,Dalian University of Technology | Yu H.,Dalian University of Technology | Wang Z.,Dalian University of Technology
Chemical Communications | Year: 2014

This report presents the synthesis of a tetraphenyladamantane-based microporous polycyanurate network with a BET surface area of 843 m2 g-1 and a pore size of 7.8 Å. It uptakes 98.0 wt% benzene (298 K, P/P0 = 0.9), 1.49 wt% H2 (77 K/1 bar) and 12.8 wt% CO2 (273 K/1 bar) with CO2/N2 selectivity of up to 112. © 2014 the Partner Organisations.

Zhao Z.,Dalian University of Technology | Dai Y.,Dalian University of Technology | Ge G.,Dalian University of Technology | Wang G.,Dalian University of Technology
ChemCatChem | Year: 2015

Nitrogen-doped carbon nanotubes (CNTs) with defect- and C=O-group-rich surface features were fabricated through a facile and scalable physical dry milling and subsequent pyrolysis approach of carbon nanotubes and melamine in the presence of guanidine nitrate. The catalytic performance of the as-prepared N-doped CNTs with diverse guanidine nitrate dosages and pyrolysis temperatures for direct dehydrogenation of ethylbenzene to styrene under oxidant- and steam-free conditions was measured. Various characterization techniques including high-resolution transmission electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy, nitrogen-adsorption and thermogravimetric analysis, and Raman spectroscopy were employed to investigate the structure and surface properties, as well as to explore the relationship between catalyst nature and catalytic performance. It is found that the addition of guanidine nitrate in the pyrolysis process of CNT with melamine significantly affects the structure, surface properties, and catalytic performance. The optimized N-doped CNTs demonstrate steady-state styrene production rates 1.56 and 1.60 times higher than those of the parent CNTs and the established nanodiamond, as well as 6.49 times the rate of commercially available K-Fe catalyst without compromising the selectivity to styrene. The much superior catalytic performance in metal-free catalytic direct dehydrogenation can be ascribed to the C=O group- and defect-rich surface nature, the basic properties resulted from N-doping, the larger surface area and pore volume, and smaller graphitic carbon crystallites. The fabricated novel N-doped CNTs can be considered as a promising candidate for sustainable production of styrene through oxidant- and steam-free direct dehydrogenation of ethylbenzene with energy-saving and environmentally benign features. The developed defect-formation strategy in this work can be used for preparation of other metal-free carbocatalysts. © 2015 WILEY-VCH Verlag GmbH & Co.

Wang Y.-T.,Dalian University of Technology | Lu A.-H.,Dalian University of Technology | Zhang H.-L.,Dalian University of Technology | Li W.-C.,Dalian University of Technology
Journal of Physical Chemistry C | Year: 2011

Nanostructured mesoporous manganese oxides were easily prepared by mixing KMnO4 with ascorbic acid in an aqueous solution under ambient conditions. The obtained manganese oxides were identified as having an α-MnO2 tunnel structure composed of an edge-shared network of [MnO6] octahedra. TEM observations revealed that the obtained MnO2 materials had three-dimensional frameworks which consisted of homogeneous nanoparticles with sizes of ca. 5 nm. Nitrogen sorption analyses showed that these MnO2 nanoparticles exhibited a type IV isotherm, indicating a mesoporous character. Large surface areas up to 284 m2 g-1 were recorded. The electrochemical performances of the synthesized α-MnO2 nanoparticles as supercapacitor electrode materials were studied using cyclic voltammetry and galvanostatic charge-discharge cycling in a three-electrode system at a potential range from 0 to 1.0 V vs a saturated calomel electrode in 0.5 M sodium sulfate solution. The result showed that mesoporous MnO2 with three-dimensional frameworks exhibit a high capacitance up to ∼ 200 F g-1. Furthermore, a hybrid supercapacitor was assembled by using MnO2 mixed with a small amount of activated carbon as the positive electrode and activated carbon as the negative electrode in a 0.5 M Na2SO4 electrolyte. By balancing the mass of MnO2 and activated carbon, a practical cell voltage of 1.8 V could be obtained in aqueous medium with a capacitance of 23.1 F g-1. After 1200 cycles, the maximum energy density is 10.4 Wh kg-1 and power density is 14.7 kW kg-1. Thus, the obtained αMnO2 nanoparticles are suitable for use as supercapacitor electrode materials. © 2011 American Chemical Society.

Liu C.,Dalian University of Technology
ICIC Express Letters | Year: 2011

In the view of the irrelativeness between service and Random Early Detection (RED) a new queue management algorithm of Oriented Service RED (OSRED) is proposed. The new algorithm forecasts the state of queue and contrasts the current state and future state and then adjusts the loss function. This paper uses the NS-2 to simulate and contrast the new queue management algorithm and the results indicate that it's effective to decline the loss of data. In addition it can reduce the time delay of end-to-end effectively under the premise of guaranteeing the throughput. ICIC International ©2011 ISSN.

Zhang X.,Dalian University of Technology | Peng W.,Dalian University of Technology
Optics Express | Year: 2015

We present a novel fiber Fabry-Perot (FP) interference salinity sensor based on polyimide (PI) diaphragm. With an increase in water salinity, the PI diaphragm shrinks, and the PI diaphragm constriction causes the increase of the width of the air-gap, which causes the red shift of the interference fringes. We fabricated salinity sensor prototypes with different air-gap lengths and 20μm PI diaphragm. When salinity increases from 0mol/L to 5.47mol/L, the maximum sensitivity is 0.45nm/(mol/L). We verify that the sensitivity can be enhanced by reducing air-gap cavity length. We also choose appropriate air cavity length and PI diaphragm length to solve the cross-sensitivity between temperature and salinity. As a robust and ultra-compact salinity sensor, which is easy to be fabricated and need no alignment, this fiber interferometer can be applied for real-time salinity sensing applications. © 2015 Optical Society of America.

Li X.,Dalian University of Technology | Wan K.,Dalian University of Technology
Computers and Geotechnics | Year: 2011

Based on the bridging scale method (BSM) initially presented in nano mechanics [1,2], a new version of the BSM that couples discrete particle assembly modeling using the discrete element method (DEM) and Cosserat continuum modeling using the finite element method (FEM) at both micro-macro scale levels respectively is proposed for multiscale analysis of granular materials. The DEM is only applied to the limited localized regions for accurately simulating discontinuous failure phenomena in microscopic scale, meantime, the FEM that costs much less computational time and storage space covers the whole domain, with permitting to adopt different time step sizes for the time integration schemes in coarse and fine scales respectively. As a consequence, both computational accuracy and efficiency of the proposed BSM are greatly enhanced. With a bridging scale displacement (including translations and rotations) decomposition and based on the virtual work principle applied to the FEM nodes of the Cosserat continuum and the particle centers of the discrete particle assembly respectively, two decoupling sets of equations of motion of the combined coarse-fine scale system are formulated. The interfacial condition between the coarse and fine scale regions in the quasi-static and dynamic loading cases are presented and discussed. The non-reflecting boundary condition and its implementation, which is capable of effectively eliminating spurious reflected waves at the interfaces between the coarse and fine scale regions, are described in detail. The numerical results for 2D example problems demonstrate the applicability and advantages of the present BSM, and the performances of the non-reflecting boundary condition implemented to simulate dynamical responses in geo-structures composed of granular materials. © 2011 Elsevier Ltd.

Gong J.-X.,Dalian University of Technology | Yi P.,Dalian University of Technology
Structural and Multidisciplinary Optimization | Year: 2011

In the first-order reliability method (FORM), the HL-RF iterative algorithm is a recommended and widely used one to locate the design point and calculate the reliability index. However it may fail to converge if the limit state surface at the design point is highly nonlinear. In this paper, an easy iterative algorithm, which introduces a new step length to control the convergence of the sequence and can be named as finite-step-length iterative algorithm, is present. It is proved that the HL-RF method is a special case of this proposed algorithm when the step length tends to infinity and the reason why the HL-RF diverges is illustrated. This proposed algorithm is much easier than other optimization schemes, especially than the modified HL-RF algorithm, because the process of line search for obtaining the step length is not needed. Numerical results indicate that the proposed algorithm is effective and as simple as the HL-RF but more robust. © 2010 Springer-Verlag.

Liu S.,Dalian University of Technology | Qiao H.,Dalian University of Technology
Structural and Multidisciplinary Optimization | Year: 2011

In order to solve elasticity problems with dual extension/compression modulus this paper presents a technique that employ Heaviside function to describe the nonlinear relationship of stress and material modulus smoothing the constitutive discontinuity. An initial stress technique is utilized in the FEM based numerical analysis, which may lead to a higher computing efficiency since the stiffness matrix needs to be triangularized only once in the whole computing, moreover, avoid the inconvenience induced by choosing shear modulus in the conventional iterative algorithm. Furthermore, a multimaterial model is proposed to formulate the topology optimization problem for bridge layout designs. Two types of materials which are concrete and steels are distributed within the design domain to accommodate design need. In addition, sensitivity of the new material model is derived using the adjoint method. The effectiveness of the present design methodology and optimization scheme is then demonstrated through numerical examples. © Springer-Verlag 2010.

Yu Q.,Dalian University of Technology | Zhou X.,Dalian University of Technology
Photonic Sensors | Year: 2011

Pressure sensors based on fiber-optic extrinsic Fabry-Perot interferometer (EFPI) have been extensively applied in various industrial and biomedical fields. In this paper, some key improvements of EFPI-based pressure sensors such as the controlled thermal bonding technique, diaphragm-based EFPI sensors, and white light interference technology have been reviewed. Recent progress on signal demodulation method and applications of EFPI-based pressure sensors has been introduced. Signal demodulation algorithms based on the cross correlation and mean square error (MSE) estimation have been proposed for retrieving the cavity length of EFPI. Absolute measurement with a resolution of 0.08 nm over large dynamic range has been carried out. For downhole monitoring, an EFPI and a fiber Bragg grating (FBG) cascade multiplexing fiber-optic sensor system has been developed, which can operate in temperature 300 °C with a good long-term stability and extremely low temperature cross-sensitivity. Diaphragm-based EFPI pressure sensors have been successfully used for low pressure and acoustic wave detection. Experimental results show that a sensitivity of 31 mV/Pa in the frequency range of 100 Hz to 12.7 kHz for aeroacoustic wave detection has been obtained. ©The Authors(s) 2010.

Shi Y.,Dalian University of Technology | Ju B.,Dalian University of Technology | Zhang S.,Dalian University of Technology
Carbohydrate Polymers | Year: 2012

We designed a new tertiary amine starch ether (2,4-bis(dimethylamino)-[1,3, 5]-triazine-6-yl)-starch (BDATS) via etherification of starch with 2,4-bis(dimethylamino)-6-chloro-[1,3,5]-triazine (BDAT), which demonstrated a reversible pH response in aqueous solution. BDATS could be utilized as an effective flocculant because of its favorable interaction with anionic dyes. The flocculation was solution pH dependent and that color removal as high as 97% was possible at pH 2. BDATS shows high flocculation capacity, with the maximum flocculation capacity (DS = 0.63) at 1158 mg g -1 for C.I. Reactive Red 141, 873 mg g -1 for C.I. Acid Red 1 and 2296 mg g -1 for C.I. Acid Blue 324, respectively. The theoretical flocculation capacity was calculated, and the results showed that the experimental flocculation capacity was near to the theoretical one. At pH 8, the dye-loaded flocculant could be regenerated and the recovery ratio of the flocculant was 80%. After five cycles of flocculation/regeneration, color removal ratio was still above 94%. BDATS made it a good candidate for an effective re-cycled flocculant for the treatment of colored effluents. © 2011 Elsevier Ltd All rights reserved.

Li X.,Dalian University of Technology | Dutta P.K.,Ohio State University
Journal of Physical Chemistry C | Year: 2010

Dimethylmethylphosphonate (DMMP) is a simulant for the highly toxic organophosphate nerve agent Sarin (GB). The influence of DMMP on the ionic conductivity of zeolite Y is investigated by impedance spectroscopy. In the presence of 20-100 ppm of DMMP, the ionic conductivity of the sodium exchanged form of the zeolite showed an increase. The interaction between DMMP and the zeolite was elucidated by examining different cation-exchanged zeolites as well as external surface modification with ceria to deactivate acidic groups. A mechanism involving the binding of the sodium cation with the phosphonate group of DMMP that results in facilitated inter cage motion of the cation is proposed. The change in impedance measured at a single frequency of 3000 Hz allows for the use of Na+-exchanged zeolite Y as a sensor for detecting ppm level of DMMP. Sensing data were obtained over a temperature range of 300-350 °C, with best results at 320 °C. This device exhibited minimal response to CO, NH3, methane, and propane, possible interferents in the ambient air. © 2010 American Chemical Society.

Yang F.,Dalian University of Technology | Lu H.,Dalian University of Technology | Yang M.-H.,University of California at Merced
IEEE Transactions on Image Processing | Year: 2014

While numerous algorithms have been proposed for object tracking with demonstrated success, it remains a challenging problem for a tracker to handle large appearance change due to factors such as scale, motion, shape deformation, and occlusion. One of the main reasons is the lack of effective image representation schemes to account for appearance variation. Most of the trackers use high-level appearance structure or low-level cues for representing and matching target objects. In this paper, we propose a tracking method from the perspective of midlevel vision with structural information captured in superpixels. We present a discriminative appearance model based on superpixels, thereby facilitating a tracker to distinguish the target and the background with midlevel cues. The tracking task is then formulated by computing a target-background confidence map, and obtaining the best candidate by maximum a posterior estimate. Experimental results demonstrate that our tracker is able to handle heavy occlusion and recover from drifts. In conjunction with online update, the proposed algorithm is shown to perform favorably against existing methods for object tracking. Furthermore, the proposed algorithm facilitates foreground and background segmentation during tracking. © 2013 IEEE.

Zhong W.,Dalian University of Technology | Lu H.,Dalian University of Technology | Yang M.-H.,University of California at Merced
IEEE Transactions on Image Processing | Year: 2014

In this paper, we propose a robust object tracking algorithm based on a sparse collaborative model that exploits both holistic templates and local representations to account for drastic appearance changes. Within the proposed collaborative appearance model, we develop a sparse discriminative classifier (SDC) and sparse generative model (SGM) for object tracking. In the SDC module, we present a classifier that separates the foreground object from the background based on holistic templates. In the SGM module, we propose a histogram-based method that takes the spatial information of each local patch into consideration. The update scheme considers both the most recent observations and original templates, thereby enabling the proposed algorithm to deal with appearance changes effectively and alleviate the tracking drift problem. Numerous experiments on various challenging videos demonstrate that the proposed tracker performs favorably against several state-of-the-art algorithms. © 1992-2012 IEEE.

Ding Y.,Dalian University of Technology
Construction and Building Materials | Year: 2011

Currently there are only few research results for predicting the relationship between deflection and the crack mouth opening displacement (CMOD) of steel fibre reinforced concrete (SFRC) beams. A series of bending beam tests on SFRC, with different fibre contents and fibre types have been carried out. Based on the experimental results a model for predicting the relation between the deflection and CMOD of SFRC has been established. This model relies on the load-deflection relation and the load-CMOD relation of bending beam. A well agreement has been found between the suggested mode and the test results of other research. The results of this mode indicate that the load-deflection diagram is very similar to that of the load-CMOD diagram, and there is a linear relation between the mid-span deflection and CMOD of SFRC. © 2010 Elsevier Ltd. All rights reserved.

Ma C.,Dalian University of Technology | Wang X.,Dalian University of Technology
Nonlinear Dynamics | Year: 2012

In this paper, we investigate the impulsive control and synchronization of a new unified hyperchaotic system. This new system unifies both the hyperchaotic Lorenz system and the hyperchaotic Chen system. Some conditions are given to guarantee the global asymptotic stability of the controlled and synchronized system. The control gains and impulsive intervals are both variable. Moreover, we estimate the upper bound of impulsive interval for stable control and synchronization. Simulations are included to show the effectiveness of the theoretical results. © 2012 Springer Science+Business Media B.V.

Yang W.,Dalian University of Technology | Liu C.,Dalian University of Technology | Qiu J.,Dalian University of Technology
Chemical Communications | Year: 2010

A highly efficient protocol for the Pd(OAc)2-catalyzed aerobic Suzuki reaction of aryl chlorides is reported, which is proposed to be promoted by the N,O-bidentate ligand formed in situ via the hydrogen bond of solvents. © 2010 The Royal Society of Chemistry.

Sun J.,Dalian University of Technology | Zhong F.,Dalian University of Technology | Zhao J.,Dalian University of Technology
Dalton Transactions | Year: 2013

Perylenebisimide (PBI) was used to prepare CN cyclometalated Ir(iii) complexes that show strong absorption of visible light and it is the first time the long-lived triplet excited state of PBI chromophore was observed in a transition metal complex (τT = 22.3 μs). Previously, the lifetime of the triplet state of PBI in transition metal complexes was usually shorter than 1.0 μs. Long-lived triplet excited states are useful for applications in photocatalysis or other photophysical processes concerning triplet-triplet-energy-transfer. PBI and amino-PBI were used for preparation of cyclometalated Ir(iii) complexes (Ir-2 and Ir-3), in which the PBI chromophore was connected to the coordination center via CC π-conjugation bond. The new complexes show strong absorption in visible region (ε = 34200 M -1 cm-1 at 541 nm for Ir-2, and ε = 19000 at 669 nm for Ir-3), compared to the model complex Ir(ppy)(bpy)[PF6] Ir-1 (ε < 5000 M-1 cm-1 in the region beyond 400 nm). The nanosecond time-resolved transient absorption and DFT calculations indicated that PBI-localized long-lived 3IL states were populated for Ir-2 and Ir-3 upon photoexcitation. The complexes were used as triplet photosensitizers for 1O2-mediated photooxidation of 1,5-dihydronaphthalene to produce juglone, an important intermediate for preparation of anti-cancer compounds. 1O2 quantum yields (ΦΔ) up to 91% were observed for the new Ir(iii) complexes and the overall photosensitizing ability is much higher than the conventional Ir(iii) complex Ir-1, which shows the typical weak visible light absorption in visible region. Our results are useful for preparation of transition metal complexes that show strong absorption of visible light and long-lived triplet excited state and for the application of these complexes in photocatalysis. This journal is © The Royal Society of Chemistry 2013.

Shen S.,Dalian University of Technology | Bi F.,Dalian University of Technology | Guo Y.,Dalian University of Technology
International Journal of Heat and Mass Transfer | Year: 2012

Several dimensionless parameters are studied to describe their effects on the deformation of a droplet after impact on a 2D round surface by using lattice Boltzmann implementation of pseudo-potential model. Four typical deformation process can be found: moving, spreading, nucleating and falling. In addition, in some special cases, part splashing is involved. It is observed that impact velocity of droplet has a significant influence on the droplet impacting dynamics. With the increasing of the impact velocity, different states have been found during the process. Moreover, when the surface is hydrophobic, splash occurs. © 2012 Elsevier Ltd. All rights reserved.

Huang L.,Dalian University of Technology | Yu X.,Dalian University of Technology | Wu W.,Dalian University of Technology | Zhao J.,Dalian University of Technology
Organic Letters | Year: 2012

C 60-styryl Bodipy dyads that show strong absorption of visible light (ε = 64 600 M -1 cm -1 at 657 nm) and a long-lived triplet excited state (τ T = 123.2 μs) are prepared. The dyads were used as heavy-atom-free organic triplet photosensitizers for photooxidation of 1,5-dihydroxynaphthalene via the photosensitizing of singlet oxygen ( 1O 2). The photooxidation efficiency of the dyads compared to the conventional Ir(III) complex 1O 2 photosensitizer increased 19-fold. © 2012 American Chemical Society.

Yang W.,Dalian University of Technology | Xu L.,Dalian University of Technology
Physical Review D - Particles, Fields, Gravitation and Cosmology | Year: 2013

In this paper, we investigate a unified dark fluid model with a fast transition and entropic perturbations. An effective sound speed is designated as an additional free model parameter when the entropic perturbations are included, and, if the entropic perturbations are zero, the effective sound speed will decrease to the adiabatic sound speed. In order to analyze the viability of the unified model, we calculate the squared Jeans wave number with the entropic perturbations. Furthermore, by using the Markov Chain Monte Carlo method, we perform a global fitting for the unified dark fluid model from the type Ia supernova Union 2.1, baryon acoustic oscillation, and the full information of the cosmic microwave background measurement given by the WMAP 7 yr data points. The constrained results favor a small effective sound speed. Compared to the cosmological constant and cold dark matter, it is found that the cosmic observations do not favor the phenomenon of a fast transition for the unified dark fluid model. © 2013 American Physical Society.

Wang J.-B.,Shenyang Aerospace University | Wang J.-J.,Dalian University of Technology
Computers and Operations Research | Year: 2014

This paper investigates flowshop scheduling problems with a general exponential learning effect, i.e., the actual processing time of a job is defined by an exponent function of the total weighted normal processing time of the already processed jobs and its position in a sequence, where the weight is a position-dependent weight. The objective is to minimize the makespan, the total (weighted) completion time, the total weighted discounted completion time, and the sum of the quadratic job completion times, respectively. Several simple heuristic algorithms are proposed in this paper by using the optimal schedules for the corresponding single machine problems. The tight worst-case bound of these heuristic algorithms is also given. Two well-known heuristics are also proposed for the flowshop scheduling with a general exponential learning effect. © 2013 Published by Elsevier Ltd.

Xiao N.,Dalian University of Technology | Zhou Y.,Dalian University of Technology | Ling Z.,Dalian University of Technology | Qiu J.,Dalian University of Technology
Carbon | Year: 2013

A carbon nanofiber (CNF)/carbon foam composite was fabricated from coal liquefaction residue (CLR) through a procedure involving template synthesis of carbon foam and catalytic chemical vapor deposition (CCVD) treatment. The high solubility and high pyrolysis yield make CLR a promising carbon precursor for the synthesis of carbon materials using the template method. The carbon foam has cell size of about 500 μm and a porosity as high as 95 vol.%. Fe species naturally present in the CLR disperse homogeneously on the surface of the carbon foam acting as a catalyst in the CCVD process. After the CCVD treatment, the whole surface of the carbon foam is covered by entangled CNFs with external diameters of 20-100 nm and lengths of several tens of micrometers. The obtained CNF/carbon foam composites are effective selective adsorbents in the separation of oil and water, through a combination of hydrophobicity and capillary action. © 2013 Elsevier Ltd.

Zhang J.,Dalian University of Technology | Jin L.,Dalian University of Technology | Jin L.,East China University of Science and Technology | Cheng J.,Dalian University of Technology | Hu H.,Dalian University of Technology
Carbon | Year: 2013

Hierarchical porous carbons were prepared from a coal liquefaction residue (CLR) and two coals, Shenhua (SH) coal with low and Shengli (SL) coal with high ash content, by KOH activation with the addition of some additives, and used as the electrode for supercapacitors. Two metal oxides (MgO and Al 2O3) and three organic materials (sugar, urea and cetyltrimethylammonium bromide) were used as the additives, to investigate their effects on the structure and capacitive performance of the resultant carbons. The results show that the metal oxide and/or its salt formed by the reaction with KOH can serve as space fillers of nanopores in the carbonized carbon, while the gases produced by the decomposition of the organic additive can develop and/or widen some pores. Both help the carbon produced from CLR or the SH coal with low ash content to have additional meso- and macropores, but destroy the structure of the carbon from the SL coal with high ash content. Compared with the carbon without any additive, the optimized hierarchical porous carbon with each additive shows a smaller equivalent resistance, much higher capacitance in a wide range of charge-discharge rates and excellent cycle stability when the carbon was used as supercapacitor electrode. © 2012 Elsevier Ltd. All rights reserved.

Zhang J.,Shanxi Normal University | Zhang J.,Dalian University of Technology | Zhao J.,Dalian University of Technology
Carbon | Year: 2013

The graphene grain boundaries with periodic length up to 18 Å have been studied using density functional theory. Atomic structures, thermodynamic stabilities and electronic properties of 40 grain boundaries with symmetric and nonsymmetric structures were investigated. According to the arrangements of pentagons and heptagons on the boundary, grain boundaries were cataloged into four classes. Some nonsymmetric grain boundaries constructed here have identical misorientation angles to the experimentally observed ones. The formation energies of grain boundaries can be correlated with the misorientation angle and inflection angle. Nonsymmetric grain boundaries possess comparable formation energies to their symmetric counterparts when the periodic length along the defect line is larger than 1 nm. Analysis of electronic density of states shows that the existence of a grain boundary usually increases the density of states near the Fermi level, whereas some symmetric grain boundaries can open a small band gap due to local sp2-to-sp3 rehybridization. © 2012 Elsevier Ltd. All rights reserved.

Liu D.,Dalian University of Technology | Ren H.,Dalian University of Technology | Deng L.,Dalian University of Technology | Zhang T.,Dalian University of Technology
ACS Applied Materials and Interfaces | Year: 2013

Four heteroleptic bis-cyclometalated iridium(III) complexes containing 2-aryl-benzothiazole ligands, in which the aryl is dibenzofuran-2-yl [Ir(O-bt)2(acac)], dibenzothiophene-2-yl [Ir(S-bt) 2(acac)], dibenzothiophene-S,S-dioxide-2-yl [Ir(SO 2-bt)2(acac)] and 4-(diphenylphosphoryl)phenyl [Ir(PO-bt)2(acac)], have been synthesized and characterized for use in organic light-emitting diodes (OLEDs). These complexes emit bright yellow (551 nm) to orange-red (598 nm) phosphorescence at room temperature, the peak wavelengths of which can be finely tuned depending upon the electronic properties of the aryl group in the 2-position of benzothiazole. The strong electron-withdrawing aryls such as dibenzothiophene-S,S-dioxide2-yl and 4-(diphenylphosphoryl)phenyl caused bathochromatic shift of the iridium complex phosphorescence. These iridium complexes were used as doped emitters to fabricate yellow to orange-red OLEDs and good performance was obtained. In particular, a maximum luminance efficiency of 58.4 cd A-1 (corresponding to 30.6 lm W-1 and 19%) with CIE coordinates of (0.45, 0.52) was achieved for Ir(O-bt)2(acac)-based yellow device. Furthermore, the yellow emitting Ir(S-bt)2(acac) was used to fabricate two-element white OLED that exhibited a high efficiency of 32.4 cd A-1 with CIE coordinates of (0.28, 0.44). © 2013 American Chemical Society.

Zhang X.,Dalian University of Technology | Qu Z.,Dalian University of Technology | Yu F.,Dalian University of Technology | Wang Y.,Dalian University of Technology
Journal of Catalysis | Year: 2013

We report an Ag/SBA-15 catalyst with low loading (1.42 wt%) that shows excellently high activity in CO oxidation at room temperature after oxygen pretreatment at 900 °C. A 98% conversion of CO is achieved at 20 °C (T98 = 20 °C). An evaporation-deposition-diffusion mechanism for Ag/SBA-15 catalyst is proposed. The oxygen adsorbate-induced decrease in the surface-free energy at 900 °C induces the evaporated silver atoms to be redeposited on the support, and meanwhile diffuse into the channels of SBA-15, forming more highly dispersed small silver particles inside the channels. The favorable structure of silver catalyst for CO oxidation is believed to arise from the synergistic effect of oxygen atmosphere, high temperature (900 °C), and the channel of SBA-15. In addition, the formation of Ag+ on the surface of support after oxygen pretreatment at 900 °C is also suggested to be essential for the following reduction and high catalytic activity for CO oxidation. © 2012 Elsevier Inc. All rights reserved.

Luo C.,Dalian University of Technology | Wang X.,Dalian University of Technology
PLoS ONE | Year: 2013

A novel algebraic approach is proposed to study dynamics of asynchronous random Boolean networks where a random number of nodes can be updated at each time step (ARBNs). In this article, the logical equations of ARBNs are converted into the discrete-time linear representation and dynamical behaviors of systems are investigated. We provide a general formula of network transition matrices of ARBNs as well as a necessary and sufficient algebraic criterion to determine whether a group of given states compose an attractor of lengths in ARBNs. Consequently, algorithms are achieved to find all of the attractors and basins in ARBNs. Examples are showed to demonstrate the feasibility of the proposed scheme. © 2013 Luo and Wang.

Kang F.,Dalian University of Technology | Li J.,Dalian University of Technology
Journal of Computing in Civil Engineering | Year: 2016

Probabilistic stability analysis is an effective way to take uncertainties into account in evaluating the stability of slopes. This paper presents an intelligent response surface method for system probabilistic stability evaluation of soil slopes. Artificial bee colony algorithm (ABC) optimized support vector regression (SVR) is used to establish the response surface to approximate the limit-state function. Then Monte Carlo simulation is performed via the ABC-SVR response surface to estimate system failure probability. The proposed methodology is verified in three case examples and is also compared with some well-known or recent algorithms for the problem. Results show that the new approach is promising in terms of accuracy and efficiency. © 2015 American Society of Civil Engineers.

Zhou H.,Dalian University of Technology | Wang Y.-B.,Dalian University of Technology
ChemCatChem | Year: 2014

By employing 1,1,3,3-tetramethyl-1,3-(pinacolboryl)disiloxane as a novel silicon source, the N-heterocyclic carbene copper complex catalyzed hydrosilylation of terminal alkynes was developed to prepare vinyldisiloxanes in a highly regio- and stereoselective manner. A number of functional groups, including ether, ester, cyano, nitro, halo, hydroxyl, cyclopropyl, and aryl groups, were tolerated under the optimized conditions. A mechanistic investigation was undertaken by using density functional theory calculations. This approach allows facile entry to unsymmetrical disubstituted (E)-alkenes by Pd-catalyzed cross-coupling reactions. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Liu H.,Dalian University of Technology | Zhang H.W.,Dalian University of Technology
Computational Materials Science | Year: 2013

A multi-node extended multiscale finite element method is developed for 2D elastostatic analysis of the computational models with various microstructures. In addition, an adaptive algorithm is proposed for the coarse-scale mesh based on the developed multiscale method. Then, the basic principles of the multi-node extended multiscale finite element method are introduced in detail. To verify the effectiveness of the adaptive algorithm, some representative numerical experiments are carried out. By comparing with the reference solutions, which are obtained by the standard finite element method on the fine-scale mesh, it can be seen that multiscale solutions with high accuracy will be calculated by combining the developed multiscale method and the proposed adaptive algorithm. Finally, a nearly optimal distribution of macroscopic nodes on the fixed coarse-scale mesh can be found by using the proposed adaptive algorithm. Thus, the contradiction between the amount of calculation and computational accuracy, to some extent, can be balanced by using the adaptive multi-node extended multiscale finite element method. © 2013 Elsevier B.V. All rights reserved.

Li D.,Dalian University of Technology | Han M.,Dalian University of Technology | Wang J.,Chinese University of Hong Kong
IEEE Transactions on Neural Networks and Learning Systems | Year: 2012

In this paper, a robust recurrent neural network is presented in a Bayesian framework based on echo state mechanisms. Since the new model is capable of handling outliers in the training data set, it is termed as a robust echo state network (RESN). The RESN inherits the basic idea of ESN learning in a Bayesian framework, but replaces the commonly used Gaussian distribution with a Laplace one, which is more robust to outliers, as the likelihood function of the model output. Moreover, the training of the RESN is facilitated by employing a bound optimization algorithm, based on which, a proper surrogate function is derived and the Laplace likelihood function is approximated by a Gaussian one, while remaining robust to outliers. It leads to an efficient method for estimating model parameters, which can be solved by using a Bayesian evidence procedure in a fully autonomous way. Experimental results show that the proposed method is robust in the presence of outliers and is superior to existing methods. © 2012 IEEE.

Luo Y.,Northwestern Polytechnical University | Luo Y.,Chinese University of Hong Kong | Wang M.Y.,Chinese University of Hong Kong | Kang Z.,Dalian University of Technology
Computer Methods in Applied Mechanics and Engineering | Year: 2013

By introducing a new reduction parameter into the Kreisselmeier-Steihauser (K-S) function, this paper presents a general K-S formulation providing an approximation to the feasible region restricted by active constraints. The approximation is highly accurate even when the aggregation parameter takes a relatively small value. Numerical difficulties, such as high nonlinearity and serious violation of local constraints that may be exhibited by the original K-S function, are thus effectively alleviated. In the considered topology optimization problem, the material volume is to be minimized under local von Mises stress constraints imposed on all the finite elements. An enhanced aggregation algorithm based on the general K-S function, in conjunction with a " removal and re-generation" strategy for selecting the active constraints, is then proposed to treat the stress constraints of the optimization problem. Numerical examples are given to demonstrate the validity of the present algorithm. It is shown that the proposed method can achieve reasonable solutions with a high computational efficiency in handling large-scale stress constrained topology optimization problems. © 2012 Elsevier B.V.

Yuan F.-Q.,CAS Changchun Institute of Applied Chemistry | Yuan F.-Q.,University of Chinese Academy of Sciences | Han F.-S.,CAS Changchun Institute of Applied Chemistry | Han F.-S.,Dalian University of Technology
Advanced Synthesis and Catalysis | Year: 2013

A one-pot cascade reaction for the synthesis of polysubstituted benzofurans and naphthopyrans from simple phenols and propargylic alcohols catalyzed by iron(III) is presented. The results demonstrate that the structural specificity for the formation of furan and pyran products is controlled by the structural nature of the propargylic alcohols. Namely, benzofurans could be synthesized efficiently from phenols and secondary propargylic alcohols in the presence of 5 mol% of iron(III) chloride hexahydrate (FeCl3·6H 2O) catalyst. On the other hand, pyran derivatives were obtained exclusively when tertiary propargylic alcohols were employed. Mechanistic studies revealed that presumably due to the discriminated steric effect of secondary and tertiary propargylic alcohols, the Fe-catalyzed Friedel-Crafts (F-C) reaction of phenols with the two types of alcohols proceeds via different models. Most importantly, we have demonstrated for the first time that fully 2,3,4-substituted naphthopyrans could be synthesized efficiently via the iron-catalyzed one-pot cascade reaction. Consequently, the results presented herein provide straightforward pathways for versatile syntheses of valuable benzofuran and pyran derivatives from simple phenolic compounds and propargylic alcohols. © 2013 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Liang Y.,Dalian University of Technology | Peng W.,Dalian University of Technology | Hu R.,Dalian University of Technology | Zou H.,Dalian University of Technology
Optics Express | Year: 2013

This paper presents a nanometer-sized metallic film periodically pierced by narrow slits with ellipse walls deposited on a substrate that demonstrates special optical properties of broadband extraordinary optical transmission (BEOT). Compared to slits with straight walls, the metal slits with nonlinearly tapered ellipse walls can collect more light on the upper surface, which is coupled into a gap plasmon polariton propagating along the ellipse walls, then delivers the light at the smaller exit slit opening. In the visible spectral region, BEOT of TM-polarized light is achieved with up to 80% transmission at resonance, which is resulted from the simultaneous enhancement of zero-order slit resonance and higher-order slit resonances excited due to the existence of the substrate. The spectral range of BEOT is limited by Wood-Rayleigh anomalies and surface plasmon polariton resonances (SPPs). The BEOT spectrum of oblique incidence with small incident angle that is divided into two separate bands are also presented and analyzed theoretically. This metallic grating overcomes the low optical transmission limit of the structures with wavelength-sized grating period in visible and near-IR regions. It can be used to design nanostructured BEOT polarizer, which is an important component in novel biomimetic-based optoelectronic systems especially those in skylight polarized environment. © 2013 Optical Society of America\e.

Ji S.,Dalian University of Technology
Science China: Physics, Mechanics and Astronomy | Year: 2013

The quasi-solid-liquid phase transition exists widely in different fields, and attracts more attention due to its instinctive mechanism. The structure of force chains is an important factor to describe the phase transition properties. In this study, the discrete element model (DEM) is adopted to simulate a simple granular shear flow with period boundary condition on micro scale. The quasi-solid-liquid phase transition is obtained under various volume fractions and shear rates. Based on the DEM results, the probability distribution functions of the inter-particle contact force are obtained in different shear flow phases. The normal, tangential and total contact forces have the same distributions. The distribution can be fitted as the exponential function for the liquid-like phase, and as the Weibull function for the solid-like phase. To describe the progressive evolution of the force distribution in phase transition, we use the Weibull function and Corwin-Ngan function, respectively. Both of them can determine the probability distributions in different phases and the Weibull function shows more reasonable results. Finally, the force distributions are discussed to explain the characteristics of the force chain in the phase transition of granular shear flow. The distribution of the contact force is an indicator to determine the flow phase of granular materials. With the discussions on the statistical properties of the force chain, the phase transition of granular matter can be well understood. © Science China Press and Springer-Verlag 2013.

Xu L.,Dalian University of Technology
Physical Review D - Particles, Fields, Gravitation and Cosmology | Year: 2013

In this paper, we continue to study a unified dark fluid model with a constant adiabatic sound speed but with the entropic perturbations. When the entropic perturbations are included, an effective sound speed, which reduces to the adiabatic sound speed when the entropic perturbations are zero, has to be specified as an additional free model parameter. Because of the relations between the adiabatic sound speed and equations of state cs,ad2(a)=w(a)- dln(1+w(a))/3dln, the equation of state can be determined up to an integration constant, in principle, when an adiabatic sound speed is given. Then there are two degrees of freedom to describe the linear perturbations for a fluid. Its microscale properties are characterized by its equations of state or adiabatic sound speed and an effective sound speed. We take the effective sound speed and adiabatic sound speed as free model parameters and then use the currently available cosmic observational data sets, which include type Ia supernova Union 2.1, baryon acoustic oscillation, and WMAP 7-yr data of cosmic background radiation, to constrain the possible entropic perturbations and the adiabatic sound speed via the Markov Chain Monte Carlo method. The results show that the cosmic observations favor a small effective sound speed cs,eff2=0.00155-0. 00155+0.000319 in the 1σ region. © 2013 American Physical Society.

Xu L.,Dalian University of Technology
Physical Review D - Particles, Fields, Gravitation and Cosmology | Year: 2013

In this paper, we use the joint measurement of geometry and growth rate from matter density perturbations to constrain the holographic dark energy model. The geometry measurement includes type Ia supernovae (SN Ia) Union2.1, full information of cosmic microwave background from WMAP-7 yr, and baryon acoustic oscillation. For the growth rate of matter density perturbations, the results f(z)σ8(z) measured from the redshift-space distortion in the galaxy power spectrum are employed. Via the Markov chain Monte Carlo method, we try to constrain the model parameter space. The jointed constraint shows that c=0.750-0.0999-0.173-0.226+0.0976+0.215+0.319 and σ8=0.763-0.0465-0.0826-0.108+0.0477+0.0910+0.120 with 1, 2, 3σ regions. After marginalizing the other irrelevant model parameters, we show the evolution of the equation of state of holographic dark energy with respect to the redshift z. Though the current cosmic data points favor a phantomlike holographic dark energy universe in the future for the mean values of the model parameters, it can behave like quintessence in 3σ regions. © 2013 American Physical Society.

Yu H.,Dalian University of Technology | Xiao Y.,Dalian University of Technology | Guo H.,Dalian University of Technology
Organic Letters | Year: 2012

Inspired by the ring-open reaction of rhodamine spriolactams as typical chemodosimeters, a general strategy is proposed to conveniently and efficiently synthesize isomerically pure 5- and 6-R-tetramethylrhodamine on a larger scale. © 2012 American Chemical Society.

Cao T.,Dalian University of Technology | Zhang L.,Dalian University of Technology
Optics Express | Year: 2013

Fano resonance (FR) within the transmission spectrum is demonstrated in the near infrared (NIR) region using elliptical nanoholes array (ENA) embedding through metal-dielectric-metal (MDM) layers. For the symmetric MDM-ENA, it has been shown that a FR can be excited by the normally incident light. This FR response is attributed to the interplay between the bright modes and dark modes, where the bright modes originate from the electric resonance (localized surface plasmon resonance) caused by the ENA and the dark modes are due to the magnetic resonance (inductive-capacitive resonance) induced by the MDM multilayers. Displacement of the elliptical nanoholes from their centers breaks the structural symmetry to excite a double FR as a result of the coherent interaction of the electric resonance with two splitting sub-magnetic resonances at different wavelengths. Moreover, the degree of the asymmetry allows for the tuning of the amplitude and bandwidth of the double FR window. The sensitivity to the slight variations of the dielectric environment has been calculated and yields a figure-of-merit of 0.8RIU-1 for the symmetric MDM-ENA and 3.0RIU-1 for the asymmetric MDMENA. © 2013 Optical Society of America.

Shen H.Z.,Dalian University of Technology | Qin M.,Dalian University of Technology | Yi X.X.,Dalian University of Technology
Physical Review A - Atomic, Molecular, and Optical Physics | Year: 2013

Taking the non-Markovian effect into account, we study how to store a single photon of arbitrary temporal shape in a single atom coupled to an optical cavity. Our model applies to Raman transitions in three-level atoms, with one branch of the transition controlled by a driving pulse, and the other coupled to the cavity. For any couplings of input field to the optical cavity and detunings of the atom from the driving pulse and cavity, we extend the input-output relation from Markovian to non-Markovian dynamics. For most possible photon shapes, we derive an analytic expression for the driving pulse in order to completely map the input photon into the atom. We find that the amplitude of the driving pulse depends only on the detuning of the atom from the frequency of the cavity, i.e., the detuning of the atom to the driving pulse has no effect on the strength of the driving pulse. © 2013 American Physical Society.

Xu L.,Dalian University of Technology | Chang Y.,Dalian University of Technology
Physical Review D - Particles, Fields, Gravitation and Cosmology | Year: 2013

In this paper, we loosen the zero equation of state of dark matter to a constant wdm. By using the currently available cosmic observations, which include the type-Ia supernovae, the baryon acoustic oscillation, the WiggleZ measurements of matter power spectrum, and the cosmic microwave background radiation from the firs release of Planck data through the Markov chain Monte Carlo method, we found the equation of state of dark matter in 3σ regions: wdm=0.000707-0.000747-0.00149-0.00196+0.000746+0. 00146+0.00193. The difference between the minimum of χ2 between the ΛCDM and ΛwDM models is Δχminâ¡2=0.446 for one extra model parameter wdm. Although the currently available cosmic observations favor the ΛwDM mildly, no significant deviation from the ΛCDM model is found in 1σ regions. © 2013 American Physical Society.

Shen C.,Dalian University of Technology | Wang Z.,Dalian University of Technology
Journal of Physical Chemistry C | Year: 2014

A new microporous polyimide network (PI-ADNT) is synthesized from 1,3,5,7-tetrakis(4-aminophenyl)adamantane and naphthalene-1,4,5,8- tetracarboxylic dianhydride. Subsequently, PI-ADNT is nitrated in fuming nitric acid with different nitration time to produce three nitro-decorated porous polyimides (PI-NO2s). Their chemical structures and nitration degrees are characterized by FTIR, solid-state 13C CP/MAS NMR spectra and element analysis. The interesting evolution of porous morphology and porosity of PI-NO2s with nitration time is investigated in detail. The results show that PI-ADNT has the BET surface area of 774 m2 g-1 with microporous size centering at 0.75 nm. After nitration-modifications, PI-NO2s display decreased surface area but remarkably increased CO2 uptake up to 4.03 mmol g-1, which is superior to most of porous polymers reported in the literature. Moreover, the CO2 adsorption selectivites over CH4 and N2 in PI-NO 2s are also significantly improved in comparison with PI-ADNT. The CO2 adsorption/separation properties of PI-ADNT and its nitrated products are studied and explained in terms of the variations of porous structure and chemical composition as well as the interaction parameters between CO2 molecule and polymer skeleton such as Henry's constant, first virial coefficient, and enthalpy of adsorption. © 2014 American Chemical Society.

Cui Q.,Dalian University of Technology | Kuang H.-B.,Dalian Maritime University | Wu C.-Y.,Dalian University of Technology | Li Y.,Dalian University of Technology
Transportation Research Part A: Policy and Practice | Year: 2013

With the rapid development of Chinese economy, the demand of air transportation has increased enormously and airports are facing intensive competition, so the issue of how to enhance airport competitiveness has attracted serious concern of the public. The formation mechanism of airport competitiveness is very complex and the research is insufficient on this topic. In this paper, index system of airport competitiveness is built from four aspects: Regional Development, Production Factors, Demand Conditions and Support Industry. Dynamic formation mechanism of airport competitiveness is studied through Structure Equation Model as well as System Dynamic with the historical data of 25 Chinese airports from 2006 to 2010. Then the influencing mechanism of some important influencing factors is analyzed with the help of Vensim software, which verifies the rationality of the model. The results show that airport investment and city R&D inputs are the two most important influencing factors of airport competitiveness, which could provide guidance for decision makers on airport competitiveness cultivation. © 2012 Elsevier Ltd.

Li G.,Dalian University of Technology | Zhang B.,Dalian University of Technology | Yan J.,Dalian University of Technology | Wang Z.,Dalian University of Technology
Chemical Communications | Year: 2014

Tetraphenyladamantane-based porous poly(Schiff base)s with BET surface area (>1000 m2 g-1), CO2 uptake (15 wt%, 273 K/1 bar) and H2 uptake (1.26 wt%, 77 K/1 bar) were synthesized. The structure-directing effect of isomers of phenyl diamines on building porous architecture was investigated. © 2014 The Royal Society of Chemistry.

Cui Q.,Dalian Maritime University | Kuang H.-B.,Dalian Maritime University | Wu C.-Y.,Dalian University of Technology | Li Y.,Dalian University of Technology
Energy | Year: 2014

Energy shortage is exacerbated by energy wastage and low efficiency, so energy efficiency has become a popular research topic. However, in most studies, the inputs and outputs of energy efficiency are selected through qualitative analysis and literature review, the rationality is not convincing. In this paper, the inputs and outputs of energy efficiency are calculated by EVA (Economic Value Added method). Number of employees in energy industry, energy consumption amount and energy services amount are chosen as the inputs while CO2 emissions per capita and industrial profit amount are chosen as the outputs. DEA (Data Envelopment Analysis) and Malmquist index are applied to calculate the energy efficiencies of nine countries during 2008-2012. Each country has different reasons to explain the change of energy efficiency index and more flexible energy development plans should be implemented according to the changing reasons. Then the important influencing factors of energy efficiency are analyzed by Panel Regression Model. The results indicate that technology indices and management indices are the main factors of energy efficiency. Management indices' effect on energy efficiency index is occurred mainly through pure technical efficiency change index. Technology indices' effect on energy efficiency index is occurred mainly through technical progress change index. © 2013 Published by Elsevier Ltd.

Tang B.,Dalian University of Technology | Brennan M.J.,São Paulo State University
Journal of Sound and Vibration | Year: 2013

The vibration transmissibility characteristics of a single-degree-of- freedom (SDOF) passive vibration isolation system with different nonlinear dampers are investigated in this paper. In one configuration, the damper is assumed to be linear and viscous, and is connected to the mass so that it is perpendicular to the spring (horizontal damper). The vibration is in the direction of the spring. The second configuration is one in which the damper is in parallel with the spring but the damping force is proportional to the cube of the relative velocity across the damper (cubic damping). Both configurations are studied for small amplitudes of excitation, when some analysis can be conducted based on analytical expressions, and for large amplitudes of excitation, where the analysis is based on numerical simulations. It is found that the two nonlinear systems can outperform the linear system when force transmissibility is considered. However, for displacement transmissibility, the system with the horizontal damper exhibits some desirable properties, but the system with cubic damping does not. © 2012 Elsevier Ltd.

Zhu Q.,Dalian University of Technology | Cordeiro J.,New York University | Sarkis J.,Clark University
Ecological Economics | Year: 2012

Organizational responses to international and domestic institutional pressures may help proactive corporate environmental practices and routines diffuse to Chinese organizations, who are key participants in global product chains. Using the 2006 survey data on 377 Chinese manufacturers in six major industrial groups in Suzhou, Dalian, and Tianjin cities, we propose and test a relationship between normative, coercive and mimetic international institutional pressures and the adoption of three important proactive corporate environmental practices (routines) - ISO 14001, TQEM (total quality environmental management), and eco-auditing - by Chinese firms. We also argue for and find that this relationship is greater than that arising from corresponding normative, coercive, and mimetic internal domestic pressures. Finally, we find a positive effect of international parenting or partnering on the adoption of proactive corporate environmental practices and routines. These findings have important implications as Chinese organizations continue to go global and international organizations seek global product supply chain partners within China. © 2012 .

Zhang Z.,Dalian University of Technology | Chen J.T.,Dalian University of Technology
International Journal of Advanced Manufacturing Technology | Year: 2012

The finite element method was used in the current work to study the selection of the constitutive models, the selection of the frictional coefficients, the selection of the contact models and the selection of the physical parameters. Numerical results show that the shape of the shoulder can affect the material flows obviously and a total of about 54.3% energy can be transformed into heat in friction stir welding/friction stir processing (FSW/FSP). When the physical parameters are further considered to be functions of temperature, the predicted temperature is lower than the one in which the physical parameters are constant. When strain-hardening effect is considered, the equivalent plastic strain is decreased and the corresponding energy dissipated by plastic deformation is decreased. The effect of the frictional coefficient on the prediction of the temperature field in FSW/FSP is small when the selection of the frictional coefficient is located in a reasonable small extent. The computational costs in the simulation of FSW/FSP are not only affected by the mesh sizes and wave speed but also affected by the mesh distortions. So, mesh distortions should be considered to be minimized in the numerical modeling of FSW/FSP to reduce the computational costs. © 2011 Springer-Verlag.

Wang W.,Dalian University of Technology | Li G.,Dalian University of Technology | Li W.,Dalian University of Technology | Liu L.,Dalian University of Technology
Chemical Communications | Year: 2011

Hierarchical TS-1 with a well connected network of meso/macropores inside the zeolite crystal was directly synthesized by using caramel as the template. © 2011 The Royal Society of Chemistry.

Kang F.,Dalian University of Technology | Li J.,Dalian University of Technology | Ma Z.,Dalian University of Technology
Information Sciences | Year: 2011

A Rosenbrock artificial bee colony algorithm (RABC) that combines Rosenbrock's rotational direction method with an artificial bee colony algorithm (ABC) is proposed for accurate numerical optimization. There are two alternative phases of RABC: the exploration phase realized by ABC and the exploitation phase completed by the rotational direction method. The proposed algorithm was tested on a comprehensive set of complex benchmark problems, encompassing a wide range of dimensionality, and it was also compared with several algorithms. Numerical results show that the new algorithm is promising in terms of convergence speed, success rate, and accuracy. The proposed RABC is also capable of keeping up with the direction changes in the problems. © 2011 Elsevier Inc. All rights reserved.

Huang X.,Shenyang Aerospace University | Wang M.-Z.,Dalian University of Technology | Wang J.-B.,Shenyang Aerospace University
Computers and Industrial Engineering | Year: 2011

In the paper two resource constrained single-machine group scheduling problems with both learning effects and deteriorating jobs are considered. By learning effects, deteriorating jobs and group technology assumption, we mean that the processing time of a job is defined by the function of its starting time and position in the group, and the group setup times of a group is a positive strictly decreasing continuous function of the amount of consumed resource. We present polynomial solutions for the makespan minimization problem under the constraint that the total resource consumption does not exceed a given limit, and the total resource consumption minimization problem under the constraint that the makespan does not exceed a given limit, respectively. © 2010 Published by Elsevier Ltd. All rights reserved.

Wang J.-B.,Shenyang Aerospace University | Wang J.-J.,Dalian University of Technology
Computers and Industrial Engineering | Year: 2011

In a manufacturing system workers are involved in doing the same job or activity repeatedly. Hence, the workers start learning more about the job or activity. Because of the learning, the time to complete the job or activity starts decreasing, which is known as "learning effect". In this paper, an exponential sum-of-actual-processing-time based learning effect is introduced into single-machine scheduling. By the exponential sum-of-actual-processing-time based learning effect, we mean that the processing time of a job is defined by an exponential function of the sum-of-the-actual- processing-time of the already processed jobs. Under the proposed learning model, we show that under a sufficient condition, the makespan minimization problem, the sum of the θth (θ > 0) power of completion times minimization problem, and some special cases of the total weighted completion time minimization problem and the maximum lateness minimization problem remain polynomially solvable. © 2010 Published by Elsevier Ltd. All rights reserved.

Cao M.,Dalian University of Technology | Zhang C.,Dalian University of Technology | Wei J.,Columbia University
Construction and Building Materials | Year: 2013

Restriction of propagation and coalescence of cracks at microscopic level is one of the most effective means to achieve high properties of cement based composite. In order to improve the properties of cement based composite microcosmically, calcium carbonate whisker was introduced as a kind of microreinforcer. The effects of whisker on macro and micromechanical properties, fracture morphology, microstructures, and crack resistance of the composite with different water to binder ratios, as well as the reinforcing mechanisms were studied. The results indicated that whiskers are effective in delaying the formation and propagation of microcracks. The micromechanical mechanism is relative to the bond properties between whiskers and cement matrix. An appropriate interfacial bond strength is advantageous to optimize the reinforcing effect of whisker in cement based composite. © 2012 Elsevier Ltd. All rights reserved.

Hu H.,Dalian University of Technology | Zhao Z.,Dalian University of Technology | Wan W.,Dalian University of Technology | Gogotsi Y.,Dalian University of Technology | And 2 more authors.
Advanced Materials | Year: 2013

Chemically converted graphene aerogels with ultralight density and high compressibility are prepared by diamine-mediated functionalization and assembly, followed by microwave irradiation. The resulting graphene aerogels with density as low as 3 mg cm-3 show excellent resilience and can completely recover after more than 90% compression. The ultralight graphene aerogels possessing high elasticity are promising as compliant and energy-absorbing materials. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Wang X.,Dalian University of Technology | Han M.,Dalian University of Technology
Engineering Applications of Artificial Intelligence | Year: 2015

Multivariate time series has attracted increasing attention due to its rich dynamic information of the underlying systems. This paper presents an improved extreme learning machine for online sequential prediction of multivariate time series. The multivariate time series is first phase-space reconstructed to form the input and output samples. Extreme learning machine, which has simple structure and good performance, is used as prediction model. On the basis of the specific network function of extreme learning machine, an improved Levenberg-Marquardt algorithm, in which Hessian matrix and gradient vector are calculated iteratively, is developed to implement online sequential prediction. Finally, simulation results of artificial and real-world multivariate time series are provided to substantiate the effectiveness of the proposed method. © 2014 Elsevier Ltd.

Guan B.-O.,Jinan University | Jin L.,Jinan University | Zhang Y.,Dalian University of Technology | Tam H.-Y.,Hong Kong Polytechnic University
Journal of Lightwave Technology | Year: 2012

Fiber grating laser sensors have been attracting great interest because of their high signal-to-noise ratio and narrow linewidth that permit high resolution sensing. According to the working principle, fiber grating laser sensors can be classified into two types: wavelength encoding sensor and polarimetric heterodyning sensor. The former responds to external perturbations in terms of shift in the operation wavelength of the fiber laser, which is similar to that of fiber grating sensor. The latter converts measurand into change in beat frequency between the two orthogonal polarization modes from the fiber laser. The polarimetric fiber grating laser sensor not only has almost all advantages of passive fiber grating sensors, but also has a distinctive advantage of ease of interrogation. This is because the beat frequency is in the RF domain, which avoids the employment of expensive wavelength measurement devices. This type of sensor has been demonstrated for measurement of temperature, axial strain, lateral force, hydrostatic pressure, bending, displacement, acceleration, electric current, and acoustic and ultrasonic signal. In this paper, we review the principle, fabrication, characterization, and implementation of the polarimetric heterodyning fiber grating laser sensors, and the sensor multiplexing in the RF domain. © 2011 IEEE.

Liu T.,Dalian University of Technology | Liu T.,RWTH Aachen | Wang Y.,Beijing University of Chemical Technology
Automatica | Year: 2012

For industrial nonlinear batch processes that can be practically divided into a series of piecewise affine operating regions, a two-dimensional (2D) closed-loop iterative learning control (ILC) method is proposed for robust tracking of the set-point profile against cycle-to-cycle process uncertainties and load disturbances. Both state feedback and output feedback are considered for the control design, together with the process input and output constraints for implementation. Based on a 2D system description for the batch operation, a few synthetic performance and robust control objectives are proposed for developing the 2D ILC schemes, in combination with the 2D Lyapunov-Krasovskii functions that can guarantee monotonic state energy (or output error) decrease in both the time (during a cycle) and batch (from cycle to cycle) directions. Both the polyhedral and norm-bounded descriptions of process uncertainties are considered to derive the corresponding linear matrix inequality (LMI) conditions for the closed-loop ILC system robust stability. An important merit of these LMI conditions is that there are adjustable convergence indices prescribed for both the time and batch directions, and an adjustable robust control performance level for the closed-loop system. By specifying/optimizing these adjustable parameters to solve these LMI conditions, the 2D ILC controller can be explicitly derived for implementation. The application to a highly nonlinear continuous stirred tank reactor (CSTR) is shown to illustrate the effectiveness and merits of the proposed ILC method. © 2012 Elsevier Ltd. All rights reserved.

Quo Q.,Dalian University of Technology | Sun Y.,Dalian University of Technology | Jiang Y.,Dalian University of Technology
International Journal of Machine Tools and Manufacture | Year: 2012

Based on third-order Newtons Interpolation theory, this paper proposed one method to compute milling stability. The machining is first considered as a dynamic process expressed by a mathematical equation, and this equation integrates the regenerative effect utilizing a time delay item. The time period is discretized as a series of small elements. Then, in each time element, the third-order Newtons interpolation algorithm is used to approximate the state item of the equation. The time-period and time-delay items are expressed by liner-interpolation. After equation items are expressed using the interpolation method on the time period, a matrix denoting the machining system is built. Taking advantage of the matrix, the stability of milling process is investigated, and the convergence feature of the proposed method is also analyzed. Finally, examples of 1-dof and 2-dof dynamic systems are conducted and the comparison results show that the method is effective. © 2012 Elsevier Ltd.

Liu S.,Dalian University of Technology | Su W.,Dalian University of Technology
Structural and Multidisciplinary Optimization | Year: 2010

Conventional topology optimization is concerned with the structures modeled by classical theory of mechanics. Since it does not consider the effects of the microstructures of materials, the classical theory can not reveal the size effect due to material's heterogeneity. Couple-stress theory, which takes account of the microscopic properties of the material, is capable of describing the size effect in deformations. The purpose of this paper is to investigate the formulation for topology optimization of couple-stress material structures. The artificial material density of each element is chosen as design variable. Based on the basic idea of SIMP (Solid Isotropic Material with Penalization) method, the effective material stiffness matrix of couple-stress material is related to the artificial density by power law with penalty. The structural analysis is implemented by finite element method for couple-stress materials, and a 4-noded quadrilateral couple-stress element is formulated in which C 1 continuity requirement is relaxed. Some typical problems are solved and the optimal results based on the couple-stress theory are compared with the conventional ones. It is found that the optimal topologies of couple-stress continuum show remarkable size effect. © 2009 Springer-Verlag.

Zhang H.W.,Dalian University of Technology | Wu J.K.,Dalian University of Technology | Fu Z.D.,Dalian University of Technology
Computational Mechanics | Year: 2010

An extended multiscale finite element method is developed for small-deformation elasto-plastic analysis of periodic truss materials. The base functions constructed numerically are employed to establish the relationship between the macroscopic displacement and the microscopic stress and strain. The unbalanced nodal forces in the micro-scale of unit cells are treated as the combined effects of macroscopic equivalent forces and microscopic perturbed forces, in which macroscopic equivalent forces are used to solve the macroscopic displacement field and microscopic perturbed forces are used to obtain the stress and strain in the micro-scale to make sure the correctness of the results obtained by the downscale computation in the elastic-plastic problems. Numerical examples are carried out and the results verify the validity and efficiency of the developed method by comparing it with the conventional finite element method. © 2010 Springer-Verlag.

Wu P.,Dalian University of Technology | Wang J.,Dalian University of Technology | He C.,Dalian University of Technology | Zhang X.,Dalian University of Technology | And 3 more authors.
Advanced Functional Materials | Year: 2012

Cu 2+-based metal-organic framework (Cu-TCA) (H 3TCA = tricarboxytriphenyl amine) having triphenylamine emitters was assembled and structurally characterized. Cu-TCA features a three-dimensional porous structure consolidated by the well-established Cu 2(O 2CR) 4 paddlewheel units with volume of the cavities approximately 4000 nm 3. Having paramagnetic Cu 2+ ions to quench the luminescence of triphenylamine, Cu-TCA only exhibited very weak emission at 430 nm; upon the addition of NO up to 0.1 mM, the luminescence was recovered directly and provided about 700-fold fluorescent enhancement. The luminescence detection exhibited high selectivity - other reactive species present in biological systems, including H 2O 2, NO 3 -, NO 2 -, ONOO -, ClO - and 1O 2, did not interfere with the NO detection. The brightness of the emission of Cu-TCA also led to its successful application in the biological imaging of NO in living cells. As a comparison, lanthanide metal-organic framework Eu-TCA having triphenylamine emitters and characteristic europium emitters was also assembled. Eu-TCA exhibited ratiometric fluorescent responses towards NO with the europium luminescence maintained as the internal standard and the triphenylamine emission exhibited more than 1000-fold enhancement. © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Yang Y.-F.,Dalian University of Technology
Advances in Structural Engineering | Year: 2011

Recycled aggregate concrete-filled steel tube (RACFST) causes the recycled aggregate concrete (RAC) to be in a state of protection with the outer steel tube and thus the RAC is hardly affected by harmful environmental factors (e.g. wind, rain, moist). However, shrinkage and creep are the phenomena commonly associated with concrete-related structures, so studies on the behaviour of RACFST columns under long-term sustained loads are essential for the design of structures which include RACFST members. This study is an attempt to predict the time-dependent behaviour of RACFST columns by using the age-adjusted effective modulus method. The concrete shrinkage and creep in RACFST columns were studied experimentally, and the static bearing capacity of the tested specimens was also investigated. A theoretical model to account for the effects of concrete shrinkage and creep on RACFST columns under long-term sustained loading is developed, and comparisons of the results predicted using this model show good agreement with the test results. Formulae for the calculation of the bearing capacity of RACFST columns under long-term sustained loads are suggested.

Kang Z.,Dalian University of Technology | Luo Y.,Northwestern Polytechnical University | Li A.,University of Reims Champagne Ardenne
Structural Safety | Year: 2011

This paper investigates the formulation and numerical solution of reliability-based optimization of structures exhibiting grouped uncertain-but-bounded variations. Based on the multi-ellipsoid convex model description for grouped uncertain-but-bounded parameters, the mathematical definition of a non-probabilistic reliability index is presented for quantified measure of the safety margin. The optimal design is then formulated as a nested optimization problem. A method based on concerned performance is proposed for regularization of the reliability index constraints. The expensive computation of the non-probabilistic reliability index and its derivative is thus avoided. Numerical examples are given to illustrate the validity and efficiency of the present method. © 2011 Elsevier Ltd.

Sun X.-M.,Dalian University of Technology | Wang W.,Dalian University of Technology
Automatica | Year: 2012

This paper considers integral input-to-state stability (iISS) for a class of hybrid time-delay systems. Discrete dynamics includes impulsive and switching signals, and continuous dynamics is not necessarily stable. Based on multiple Lyapunov-Krasovskii functionals, a dwell-time bound is explicitly given to guarantee iISS of the hybrid delayed system. Compared with existing results on related problems, the obtained stability criteria can be applied to a larger class of hybrid delayed systems. Moreover, the obtained dwell-time bound is less conservative than existing ones. At last, an example related to networked control systems (NCSs) is provided to illustrate the effectiveness of the proposed result. © 2012 Elsevier Ltd. All rights reserved.

Shang Y.,Dalian University of Technology | Li S.,Dalian University of Technology | Li H.,Dalian Maritime University
Energy and Buildings | Year: 2011

In this paper, a three-dimensional model is presented to study the geo-temperature variation with the porous theory. The simulation is validated in comparison with experiment that carried out on the mode of heating. The model was used to predict the geo-temperature distribution in operation and recovery period of ground-source heat pump system. Moreover, the influencing factors including thermal conductivity, porosity, backfill material, air temperature, solar radiation energy and velocity of wind on the soil recovery process were calculated. The results show that the soil temperature recovers more quickly when heat conductivity increases and soil porosity decreases. Under the heating mode, the soil temperature recovers more quickly when the solar radiation and air temperature increase and the wind reduces. Furthermore, the results indicate that the soil properties have great effect on the soil recovery, however the environment factors have little effect. © 2010 Elsevier B.V. All rights reserved.

Huang L.,Dalian University of Technology | Zhao J.,Dalian University of Technology
Journal of Materials Chemistry C | Year: 2015

In order to switch the triplet excited states in organic compounds, dimethylaminostyryl BODIPY-C60 dyads and triads were prepared. The triplet excited states of the compounds were switched with acid/base, and the mechanism was studied with nanosecond time-resolved transient difference absorption spectroscopy. The visible light-harvesting BODIPY antennas are the electron or singlet energy donor, whereas C60 moiety is the electron/singlet energy acceptor, as well as the spin converter to produce triplet excited states. Our strategy of triplet state switching is to control either the photoinduced electron transfer (PET) or the singlet state energy transfer (EnT) from the antenna to C60 moiety by protonation of the dimethylaminostyryl BODIPY unit. Population of the triplet state was observed for the dyads with mono(4-dimethylaminostyryl) substituents on BODIPY antenna in nonpolar solvent such as toluene (τT = 168.6 μs). Formation of the charge transfer state (CTS) in polar solvent quenches the triplet excited state (τT < 10 ns). In the presence of acid, the dimethylaminostyryl BODIPY moiety is protonated, thus the electron transfer (ET) was inhibited. The cascade acid-activated EnT and the intersystem crossing (ISC) of C60 produce the triplet excited state. For the dyad and the triads with bis(4-dimethylaminostyryl) substituents on BODIPY antenna, the antenna S1 state energy level is lower than the S1 state energy level of C60; thus, no EnT to C60 exists, and no triplet state was produced upon selective excitation into the BODIPY moiety. With protonation of the amino styryl substituents, the S1 state energy level of the antenna is promoted to be higher than S1 state of C60 moiety, and as a result EnT is activated and triplet state is produced. In all the compounds, the triplet excited state is localized on the dimethylaminostyryl BODIPY moiety and not on the C60 moiety. The triplet state switching was conveyed to the singlet oxygen (1O2) photosensitizing ability of the compounds, and the variation of the singlet oxygen quantum yield, ΦΔ, is from 1.9% to 73%. © The Royal Society of Chemistry 2015.

Luo X.,Dalian University of Technology | Li X.,Dalian University of Technology | Zhou J.,Dalian University of Technology | Cheng T.,Huangshi Institute of Technology
Structural Safety | Year: 2012

First, the artificial bee colony (ABC) algorithm was used to optimize the Kriging model. A typical example was given to validate a good function fitting performance of the ABC-optimized Kriging model. Next, a structural reliability optimization method was proposed on the basis of the Kriging surrogate model, combined with the artificial bee colony optimization method and penalty function method. A nonlinear limit-state function example was provided to validate the accuracy and efficiency of the hybrid algorithm by comparing the algorithm's solution with the exact solution of the example. Finally, the proposed method was applied to earth slope reliability analysis using a commercial finite difference program to calculate the slope's factor of safety. Comparison of the results between the proposed method and the other methods shows that the proposed algorithm is the most suitable for slope reliability analysis. © 2011 Elsevier Ltd.

Zhao Z.,Dalian University of Technology | Yang H.,Dalian University of Technology | Li Y.,Dalian University of Technology | Guo X.,Dalian University of Technology
Green Chemistry | Year: 2014

This work presents a facile and clean transformation for synthesizing diverse functionalized arylamines through chemoselective reduction reaction of their corresponding substituted nitroarenes catalyzed by the supported cobalt-promoted molybdenum carbide catalyst on modified activated carbon (Co-Mo2C/AC, AC is denoted as the modified activated carbon by H 2O2 oxidation treatment). Various characterization techniques including X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), inductively coupled plasma (ICP) and H2 temperature-programmed reduction (H2-TPR) were employed to reveal the relationship between catalyst nature and catalytic performance, and the plausible reaction mechanism is also proposed. The characterization results suggest that the addition of a small amount of transition metals, especially cobalt could significantly promote the formation of a perfect molybdenum carbide crystal phase, resulting in the improvement in catalytic properties of the supported molybdenum carbide catalyst. Reaction results demonstrate that the optimized Co-Mo2C/AC catalyst shows comparable catalytic performance towards precious metals for chemoselective reduction of various aromatic nitro compounds, affording 100% yield for all substrates involved in this work (99.3% of isolated yield for model substrate). Moreover, it can be found that the catalyst could be easily recovered by filtration and recycled without obvious loss in its catalytic properties. Therefore, the developed Co-Mo2C/AC catalyst in this work can be considered as an industrially viable and cheap candidate for clean and highly-efficient production of diverse functionalized arylamines. © 2014 The Royal Society of Chemistry.

Cui Q.,Dalian Maritime University | Li Y.,Dalian University of Technology
Transportation Research Part D: Transport and Environment | Year: 2014

In this paper, transportation energy efficiency is newly defined and its inputs and outputs are obtained through literature review. Labor input, capital input and energy input are selected as the inputs, passenger turnover volume and freight turnover volume are defined as the outputs. A new model-three-stage virtual frontier DEA (three-stage virtual frontier Data Envelopment Analysis) is proposed to evaluate transportation energy efficiencies. The case of thirty Chinese PARs (provincial administrative regions) from 2003 to 2012 is applied to verify its rationality. In the three-stage virtual frontier DEA, the reference DMU (decision-making unit) set and the evaluated DMU set are two different sets so that it can distinguish the DEA efficient DMUs. And in the evaluating process, the reference DMU set remains unchanged to assure its results more reasonable than Super DEA model. The results show that transport structure and management measures have important impacts on transportation energy efficiency. © 2014 Elsevier Ltd.

Kang Z.,Dalian University of Technology | Luo Y.,Northwestern Polytechnical University
Structural and Multidisciplinary Optimization | Year: 2010

For structural systems exhibiting both probabilistic and bounded uncertainties, it may be suitable to describe these uncertainties with probability and convex set models respectively in the design optimization problem. Based on the probabilistic and multi-ellipsoid convex set hybrid model, this paper presents a mathematical definition of reliability index for measuring the safety of structures in presence of parameter or load uncertainties. The optimization problem incorporating such reliability constraints is then mathematically formulated. By using the performance measure approach, the optimization problem is reformulated into a more tractable one. Moreover, the nested double-loop optimization problem is transformed into an approximate single-loop minimization problem by considering the optimality conditions and linearization of the limit-state function, which further facilitates efficient solution of the design problem. Numerical examples demonstrate the validity of the proposed formulation as well as the efficiency of the presented numerical techniques. © 2009 Springer-Verlag.

Gao X.-W.,Dalian University of Technology
Computer Methods in Applied Mechanics and Engineering | Year: 2010

In this paper, a robust method is presented for numerical evaluation of weakly, strongly, hyper- and super-singular boundary integrals, which exist in the Cauchy principal value sense in two- and three-dimensional problems. In this method, the singularities involved in integration kernels are analytically removed by expressing the non-singular parts of the integration kernels as power series in the local distance ρ of the intrinsic coordinate system. For three-dimensional boundary integrals, the radial integration method [1] is applied to transform the surface integral into a line integral over the contour of the surface and to remove various orders of singularities within the radial integrals. Some examples are provided to verify the correctness and robustness of the presented method. © 2010 Elsevier B.V.

Zhu J.,Dalian University of Technology | Chen B.,Dalian University of Technology
Energy and Buildings | Year: 2013

Since the first Chinese passive solar house was built in 1977, a large number of passive solar houses have been built within 20 years. However, many problems appeared during the long-term utilization process, such as poor heating effect, inconvenient operation control and incomplete design standards, which lead to the development of passive solar houses stagnant in the past decade. To solve the above- mentioned problems, technical improvement and free running temperature prediction methods of passive solar house were investigated in this study. As a case study, a two-year experiment was undertaken in an improved passive solar house, located in Dalian city, northeast China, and the performance of solar air collector was investigated in winter mainly. The experimental results showed the indoor-outdoor temperature differences were about 13.4-24.5 C without auxiliary heat exchanger. According to the function of useful heat gain and solar irradiance obtained through regression analyses of experimental data, a simple free running temperature prediction formula of passive solar house for engineering application was obtained, which can be expressed as the linear superposition function of three main factors, including outdoor temperature, internal gains and solar irradiance. Taking the improved solar house as an example, a good agreement between monitored data and predicted data proved the feasibility of the prediction formula. In addition, weighed coefficients of influence factors in prediction formula were determined based on five typical cities in cold areas of China. © 2013 Elsevier B.V. All rights reserved.

Zhao L.,Dalian University of Technology | Zhang J.-L.,Dalian University of Technology | Liang R.-B.,Dalian University of Technology
Energy and Buildings | Year: 2013

Building energy consumption is an important component of the total social energy consumption, especially for large public buildings in China. Building energy conservation is one valid method for increasing energy efficiency. In order to locate the status of energy consumption for large public buildings, such as supermarket, government office buildings, hospital and campus buildings, an Internet-based energy monitoring system was developed. The implementation of this system was introduced in detail, including the principle of selecting monitoring points at the bottom layer, the design of a data collector with storage function avoiding data loss caused by network faults, and the development of database and application software at the top layer. The monitoring platform releases the energy consumption data on the web, so the authorized users can access the data any time and anywhere through Internet. In addition, the data display system is given in form of graph-charts or tables, so users can choose any kind of data they want to see, either instant values uploaded every 5 min or historic data uploaded every hour, day and month. The platform has been used in some large public buildings in Liaoning Province in China over two years, and the results confirm its feasibility and validity. © 2013 Elsevier B.V. All rights reserved.

Li S.,Dalian University of Technology
Biology of the cell / under the auspices of the European Cell Biology Organization | Year: 2012

Amplified in breast cancer 1 (AIB1) is a transcriptional coactivator of nuclear receptors and other transcription factors. It is required for animal growth and reproductive development, and has also been implicated in breast carcinogenesis. Although AIB1 is known to be covalently modified by SUMO-1, which serves to regulate its stability and transcriptional activity, the exact SUMO E3 ligase involved in its sumoylation has not been determined. In order to resolve this question, we investigated the interaction between AIB1 and different members of PIAS proteins (all are SUMO E3 ligases) through immunoprecipiation. Among the five different PIAS proteins, only PIAS1 co-immunoprecipitated with AIB1 in extract prepared from breast cancer cells (MCF-7). Over-expression of PIAS1 together with AIB1 in MCF-7 cells led to increased sumoylation of AIB1, resulting in repression of its transcriptional activity. In contrast, the PIAS1 mutant (C350S) lacking E3 ligase activity appeared to have no effect on the sumoylation of AIB1. Through sumoylation of AIB1, PIAS1 also promoted the stability of AIB1 and attenuated its interaction with estrogen receptor α (ERα), resulting in repression of the transactivation activity of ERα. In addition, MCF-7 cells co-transfected with wild-type PIAS1 and AIB1 showed about 40% reduction in cell growth, while cells co-transfected with wild-type PIAS1 and mutant AIB1 resistant to sumoylation showed about 34% increase in cell growth compared to cells transformed with wild-type AIB1 only. Taken together, these results suggested that PIAS1 may play a crucial role in the regulation of AIB1 transcriptional activity through sumoylation. Copyright © 2012 Soçiété Francaise des Microscopies and Société de Biologie Cellulaire de France.

Yang Y.-F.,Dalian University of Technology | Ma G.-L.,Dalian University of Technology
Thin-Walled Structures | Year: 2013

The behaviour of recycled aggregate concrete (RAC) filled stainless steel tube (RACFSST) stub columns and beams under short-term loadings was experimentally studied, and a total of 28 specimens, including 14 stub columns and 14 beams, were tested. The experimental investigations were carried out on circular and square specimens with recycled aggregate replacement ratio of 0, 25%, 50% and 75%, and both recycled coarse aggregate (RCA) and recycled fine aggregate (RFA) were adopted in the tests. The main objectives of these tests were threefold: first, to describe a series of tests on new composite stub columns and beams; second, to investigate the effect of cross-section type and recycled aggregate replacement ratio on the compressive and flexural behaviour of RACFSST specimens; and finally, to evaluate the accuracy of the calculated bearing capacity, bending moment capacity and section flexural stiffness of the RACFSST specimens by using the design formulae in six codes related to the design of concrete filled carbon steel tube. The experimental results showed that the RACFSST stub columns and beams under short-term loadings had the stable load versus deformation responses and the good deformation-resistant ability, and the performance of core RAC was generally enhanced due to the confinement of the outer stainless steel tube. © 2013 Elsevier Ltd.

Zhao S.,Dalian University of Technology | Chen S.,Dalian University of Technology | Yu H.,Dalian University of Technology | Quan X.,Dalian University of Technology
Separation and Purification Technology | Year: 2012

Not only for utilizing both visible and UV light but also for enhancing photogenerated charge separation capability, a hybrid photocatalyst composed of graphite-like carbon nitride (g-C 3N 4, mainly response to visible light) and TiO 2 (response to UV light) was fabricated by a hydrolysis approach. The TEM images of g-C 3N 4/TiO 2 samples displayed that TiO 2 nanoparticles dispersed well on the surface of g-C 3N 4 sheet and the average size of TiO 2 particles on g-C 3N 4 sheet was much smaller than that of TiO 2 samples without g-C 3N 4 sheet, meaning the inhibiting TiO 2 aggregation function of g-C 3N 4 sheet. The UV-Vis diffuse reflectance spectra displayed that the optical absorption range of g-C 3N 4/TiO 2 hybrid was from 300 to 450 nm, including both UV and visible light. The lower intensity of photoluminescence for g-C 3N 4/TiO 2 than those for pristine g-C 3N 4 and TiO 2, indicated that the recombination of photogenerated charge was inhibited effectively. Profiting from the above mentioned advantages, g-C 3N 4/TiO 2 showed good photocatalysis capability. The pseudo-first-order kinetic constant of phenol degradation on g-C 3N 4/TiO 2 was 2.41 and 3.12 times those on pristine g-C 3N 4 and TiO 2, respectively. We also proposed the scheme for electron-hole separation and transport at the light-driven g-C 3N 4/TiO 2 hybrid photocatalyst interface as well as the phenol degradation mechanism under full spectrum and visible light irradiation.© 2012 Elsevier B.V. All rights reserved.

Li M.,Dalian University of Technology
Journal of Sound and Vibration | Year: 2015

Analytical solutions for the vibration of a beam with axial force subjected to generalized support motion are obtained in this paper. The finite element method (FEM) is introduced to validate the analytical solution obtained by an analytical approach. The dynamic responses of clamped-clamped, pinned-pinned and clamped-pinned beams with axial tension or compression are obtained via analytical approach and FEM. Comparing results show that the analytical approach is effective. The analytical analysis shows that the resonance will occur in general when the oscillatory frequency of transverse motion or rotation of any support end is equal to the natural frequency of the beam. Moreover, several cases in which the resonance disappears even if the frequencies of support excitations are equal to the natural frequencies of the beam are detected and are validated by the FEM solution. © 2014 Elsevier Ltd. All rights reserved.

Qi C.,Dalian University of Technology | Chen X.,Dalian University of Technology | Qiu Y.,Dalian University of Technology
IEEE Transactions on Power Electronics | Year: 2013

To attenuate the peaks of harmonics, three carrier-based randomized pulse position modulation schemes are proposed for an indirect matrix converter (IMC), which, to date, have not been discussed in existing literatures. In the first scheme, to avoid commutation of a rectifier stage at instants of carrier transition, one of four different pulse positions of the rectifier stage is selected randomly based on the Markov chain. The second scheme randomly places the center of the pulse position with a limited degree of freedom, which has a lower harmonic spectrum but higher commutation frequency. The maximum degree of freedom is achieved in the third scheme, which randomly varies the pulse position by delaying its edge along entire carrier cycle, resulting in a continuous and flat harmonic spectrum, but the maximum commutation frequency in three proposed schemes. An alternative carrier of an inverter stage is applied in all the schemes to maintain smooth operation at instants of carrier transition. Effectiveness of the proposed schemes is validated through experimental tests on an IMC prototype. © 2012 IEEE.

Babel R.,McMaster University | Babel R.,Dalian University of Technology | Koshy P.,McMaster University | Weiss M.,RWTH Aachen
International Journal of Machine Tools and Manufacture | Year: 2013

Acoustic emission signals from interrupted machining operations exhibit spikes at workpiece entry and exit, which are particularly conspicuous in grinding. Although their occurrence has been widely reported, these spikes are yet to be clarified in terms of their origin or interpreted to yield useful process information. This paper hence reports on the analyses of time-averaged and raw acoustic emission signals from surface grinding, with reference to burr formation as well as dynamic and thermal effects, in order to elucidate this intriguing phenomenon. The transient spikes at the entry and exit are shown to be a consequence of the wheel establishing and losing contact with the work over the actual contact length, in terms of heat conduction and damping, which are reflected in characteristic frequency bands of the AE signal. The research is demonstrated to have consequently yielded a simple, non-destructive method for assessing the actual wheel-work contact length in grinding. © 2012 Elsevier Ltd.

Lian J.,Dalian University of Technology | Feng Z.,Dalian University of Technology
Asian Journal of Control | Year: 2013

This paper deals with the problems of passivity and passification for a class of discrete-time switched stochastic systems with time-varying delay. Based on the average dwell time approach, the pie