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Chongqing, China

Chongqing University is a key national university located in Chongqing, China,and a member of the "Excellence League". Chongqing University is also one of the "Project 211 and Project 985” universities with full support in the construction and development from the central government and the Chongqing Municipal Government. Among its various departments, Chongqing University is especially highly ranked in the Built Environment, Engineering, Technology, and Business disciplines. Wikipedia.

Chen G.,Chongqing University | Lewis F.L.,University of Texas at Arlington
International Journal of Robust and Nonlinear Control | Year: 2011

This paper investigates distributed controller design problem for a leader-follower network in the presence of communication delays. Two main contributions are made in this work. First, the second-order controlled consensus scheme for the weakly connected communication graph topology is proposed. A necessary and sufficient condition is given under which the exponential consensus is achieved. Meanwhile, the relationship among the agents' inertias, the allowable delay bound, the communication topology, the consensus convergence rate, and the control gains is unveiled. Second, the robustness performances of the distributed control scheme with respect to the communication failures and delays are provided. It is shown that if the communication failure rate and the topology switching frequency, respectively, satisfy the given bounds, the exponential second-order controlled consensus can be achieved under a bounded delay. Numerical examples are given to illustrate the theoretical results. © 2010 John Wiley & Sons, Ltd.

Zhang H.-F.,Military School of Engineering | Sun Z.,Chongqing University | Sang W.-L.,Southwest University | Sang W.-L.,CAS Institute of Theoretical Physics | Li R.,Xian Jiaotong University
Physical Review Letters | Year: 2015

With the recent LHCb data on ηc production and based on heavy quark spin symmetry, we obtain the long-distance matrix elements for both ηc and J/ψ productions, among which, the color-singlet one for ηc is obtained directly by the fit of experiment for the first time. Using our long-distance matrix elements, we can provide good description of the ηc and J/ψ hadroproduction measurements. Our predictions on J/ψ polarization are in good agreement with the LHCb data, explain most of the CMS data, and pass through the two sets of CDF measurements in the medium pt region. Considering all the possible uncertainties carefully, we obtained quite narrow bands of the J/ψ polarization curves. © 2015 American Physical Society.

Qin D.,Chongqing University
Jixie Gongcheng Xuebao/Journal of Mechanical Engineering | Year: 2011

Starting and shifting states of clutch in automatic transmission are identified on the basis of the motion states of driven plates of the clutch. Unified dynamic model is set up for the starting control of clutches in both automatic mechanical transmission (AMT) and dual clutch transmission (DCT). The linear quadratic optimal control method is used to achieve the optimum starting control of the clutches, in which the jerk is converted to one of the restrain conditions, and the minimization of sliding friction work of the clutches is set as optimal target in control. Universal optimal starting control of AMT and DCT clutches is realized through selection of state variables, setting of parameters and modifying of restrain conditions in the unified model for clutch starting of AMT, single and dual clutch starting of DCT. Simulation is carried out and then verified by experiment. The research results lay the foundation for the construction of universal development platform of the AMT and DCT automatic transmissions. © 2011 Journal of Mechanical Engineering.

Chen D.G.,Hong Kong University of Science and Technology | Tang F.,Chongqing University | Law M.-K.,University of Macau | Bermak A.,Hong Kong University of Science and Technology
IEEE Journal of Solid-State Circuits | Year: 2014

Analog-to-information converters (AICs) take advantage of the limited information bandwidth in high-frequency signals to improve the energy efficiency of front-end data converters. High-resolution image sensors often convey limited information due to the spatial redundancy between neighboring pixels. This paper proposes a mixed-signal AIC which compresses each nonoverlapping 4 × 4 pixel block in a 816 × 640 pixel prototype active-pixel sensor (APS) imager. It combines an energy-efficient charge-pump bit-image processor (BIP) with an area-efficient successive-approximation-register-single-slope (SAR-SS) hybrid analog-to-digital converter (ADC) via a charge-transfer- amplifier (CTA). The AIC is fully dynamic and consumes no static power. The ADC's capacitor array doubles as a computational device for parts of the compression algorithm which reduces its sampling rate by a factor of four. The compressed data contains direct edge information and can be decoded by a very simple receiver. The fabricated prototype consumes 12 pJ per pixel at 111 fps in the image compression mode and 48 pJ per pixel at 28.7 fps in raw data mode (9 b per pixel) under the same clock rate. To the best of our knowledge, this is the most energy-efficient compressive CMOS image sensor ever reported in the literature, thanks to the proposed AIC. © 1966-2012 IEEE.

Li B.,University of Nevada, Reno | Zhang X.Y.,Chongqing University
Scripta Materialia | Year: 2016

It is generally believed that the . 101-2101-1- twinning shear in magnesium equals 0.129 and twin growth is mediated by twinning dislocations. Starting from these notions, we analyze, in great detail, the lattice transformation from parent to twin, and prove that the twinning shear cannot be any finite value but zero. Thus, no twinning dislocations should be involved in this twinning mode and the lattice transformation is solely accomplished by atomic shuffling. Atomistic simulations and high resolution transmission electron microscopy observations unambiguously confirm our conclusion. © 2016 Elsevier B.V.

The cooling heat transfer of supercritical CO2 is simulated numerically in the horizontal helically coiled tube using RNG k-ϵ turbulence model. The parameters of the tube are: inner diameter of 4 mm, a length of 2000 mm, a pitch of 10 mm, radius of helically coiled tube of 20 mm, curvature of 0.1. It is found that the heat transfer coefficient fluctuates from top to bottom along the flow direction. On this basis, the effect of the pitch p, tube diameter of helically coiled tube d, radius of helically coiled tube R on the heat transfer coefficient (h) are studied. The results show that the h increases as the p, d, R increases and is insensitive when the p, d, R further increases to higher values. The change condition of the pressure is different with the p, d, R increasing. At the same time the contours show that the effect of the buoyancy force on h is weaker than that of the centrifugal force. A quantitative analysis is carried on to study the effect of gravity based on the setting conditions and the results shows that the effect of gravity can be ignorable on the heat transfer coefficient. The change condition of Rig is consistent with that of Gr/Re2.7 in judging the scope of the buoyancy force. The change condition of Ric/Rig indicates that the gravitational buoyancy force is more important than the centrifugal buoyancy force on the heat transfer coefficient under the setting conditions. © 2016 Elsevier Ltd. All rights reserved.

Zheng S.,Chongqing University
European Physical Journal C | Year: 2015

For minimal $$\lambda $$λ-supersymmetry, the theory stays perturbative to the GUT scale for $$\lambda \le 0.7$$λ≤0.7. This upper bound is relaxed when one either takes the criterion that all couplings are close to $$\sim $$∼4$$\pi $$π for non-perturbation or one allows for new fields at the intermediate scale between the weak and GUT scale. We show that a hidden $$U(1)_X$$U(1)X gauge sector with spontaneously broken scale $$\sim $$∼10 TeV improves this bound as $$\lambda \le 1.23$$λ≤1.23 instead. This may induce significant effects on the Higgs physics, such as decreasing fine tuning involving the Higgs scalar mass, as well as on the small $$\kappa $$κ-phenomenology. © 2015, The Author(s).

Deng D.,Chongqing University | Kiyoshima S.,Computational Mechanics Inc
Computational Materials Science | Year: 2012

To increase productivity, welding process with large heat input such as electro slag welding (ESW) process has been used to connect the joints between the diaphragm and the column plate in high-rise steel building. However, the heat input of ESW is much higher than those of the other welding processes, and the high heat input not only largely alters the properties of steel but also results in large residual stresses. Consequently, the changes of steel properties and residual stresses induced by ESW have significantly effects on the safety of a structure. In this study, a three dimension (3-D) finite element model with considering moving heat source was developed to simulate the welding temperature field, Δt 8/5 time, welding residual stress and distortion in a typical thick plate joint performed by ESW. The thermal cycles computed by finite element model were compared with experimental measurements. Meanwhile, the features of welding residual stress and distortion distributions in the ESW joint were investigated numerically. In addition, the influences of heat input on the size of heat affected-zone (HAZ), Δt 8/5 time welding residual stress and distortion were examined. The thermal cycle curve and simulated by FEM model can be used to deduce the micro-structure as well as toughness of weld zone and HAZ, while the welding residual stress distribution estimated by numerical model can be helpful to assess the structural integrity. © 2012 Elsevier B.V. All rights reserved.

Yu Y.,Chongqing University | Lui H.-S.,Chalmers University of Technology | Niow C.H.,National University of Singapore | Hui H.T.,National University of Singapore
IEEE Transactions on Wireless Communications | Year: 2011

An experimental study is performed to investigate the improvement of direction-of-arrival (DOA) estimation using the recently proposed receiving mutual impedances for mutual coupling compensation. A seven-monopole antenna array is constructed and used in DOA estimation employing the MUSIC algorithm. Comparisons are made with the case of using the conventional mutual impedances for mutual coupling compensation. All experiments are carried out inside an anechoic chamber. Results are obtained for one- and two-source experiments which indicate that the performance of DOA estimation in the presence of mutual coupling can be significantly improved when the mutual coupling effect is compensated by using the receiving mutual impedances. © 2011 IEEE.

Chen P.S.,CAS National Astronomical Observatories | Yang X.H.,Chongqing University
Astronomical Journal | Year: 2012

We collected almost all of the Galactic infrared carbon stars (IRCSs) from literature published up to the present to organize a catalog of 974 Galactic IRCSs in this paper. Some of their photometric properties in the near-, mid-, and far-infrared are discussed. © 2012. The American Astronomical Society. All rights reserved.

This study concerns the encapsulation and controlled release of both hydrophobic and hydrophilic medications with one polymer, which are delivered together as a combined therapy to treat diseased tissue. To test our hypothesis that the novel PEG-graft-PLA (PEG, polyethylene glycol; PLA, polylactic acid) can deliver both the hydrophobic and hydrophilic medications on account of its amphiphility, charge, and graft structure, PEG-graft-PLA (molecular weight of PEG = 1900) with very low critical micelle concentration was synthesized. One hydrophilic (insulin) and one hydrophobic (naproxen) model medication were loaded in separately during its self-assembly in aqueous solution. The resulting nanoparticles (NPs) were narrowly distributed and spherical, with average particle size around 200 nm, zeta potential >-10 mV, and encapsulation efficiency >50%. The NPs realized controlled release of insulin and naproxen for over 24 and 160 hours, respectively. Specifically, the bioactivity of the insulin released from the NPs was maintained. Owing to encapsulation, both for hydrophobic and hydrophilic medicines, and NPs obtained with similar size and zeta potential, as well as maintenance of bioactivity of loaded protein, we expect the applications of PEG-graft-PLA NPs in combination therapy.

Yang B.,Chongqing University | Yang B.,Nanyang Technological University | Tan K.H.,Nanyang Technological University
Journal of Structural Engineering (United States) | Year: 2013

Several structural collapse incidents indicate that failure usually starts from beam-column joints exposed to abnormal loads, especially for steel and composite structures. If the connections are sufficiently robust and there is adequate axial restraint from adjoining structures, catenary action forms in the beams and slabs, causing alternate load paths when affected columns are severely damaged, and resulting in large deformations in the beams and slabs. This paper presents experimental results of bolted-angle beam-column joints under a middle column-removal scenario. Three types of connections - including (1) web cleat, (2) top and seat angle, and (3) top and seat with web angle connections - were investigated, and three angle thicknesses (8, 10, and 12 mm) were tested. The results of the nine experimental tests conducted demonstrate the ductility and load-carrying capacities of these three connection types with different angle thicknesses in catenary action mode. When the angle thickness increases, the failure mode changes from angle fracture to bolt fracture. A component-based model is also developed to predict the behavior of bolted-angle beam-column joints up to total failure. The validation study indicates that the proposed models can represent the key responses of bolted-angle beam-column joints under a middle column-removal scenario, including the formation of flexural action at small deformation stage, the development of catenary action at large deformation stage, and fractures of the connection components at the last stage. Based on the proposed joint model, frame analyses are conducted. The analytical results of the frame models demonstrate that the conducted joint tests could represent the behavior of prototype steel frames against progressive collapse. The effect of horizontal restraint stiffness, which is critical to the development of catenary action, is also investigated. © 2013 American Society of Civil Engineers.

Wang X.,Chongqing University | Zhou G.,Huaqiao University
Reviews on Advanced Materials Science | Year: 2013

Failure of metal foams caused by compression is very common in practice, such as light-weight structural sandwich panels, packing materials and energy absorbing devices. In this paper, the uniaxial compression and indentation response of the closed-cell aluminum foams were investigated experimentally under quasi-static loading conditions. The indentation deformation was found to be almost totally restricted to a spherical cap-shape compacted zone under the indenter. The indentation strength of the closed-cell Al foam is larger than the uniaxial compressive strength because of the work done in tearing cell walls around the perimeter of the indenter and because of friction. The closed-cell Al foam exhibits an elastic-plastic type behavior under transverse uniaxial compressive loads. A long flat stress-strain curve shows that metal foam is a good energy absorption material © 2013 Advanced Study Center Co. Ltd.

Liao W.,Chongqing University | Wang Y.,Shanghai JiaoTong University | Pan E.,Shanghai JiaoTong University
International Journal of Advanced Manufacturing Technology | Year: 2012

As an increasing number of manufacturers are beginning to realize the importance of maintaining throughput, many maintenance models have been developed to enable machines to achieve near-zero downtime. However, previous maintenance models usually ignore machine's deterioration process. Therefore, this paper develops a novel data-driven machinery prognostic approach for machine performance assessment and prediction. With this prognostic information, a predictive maintenance model is proposed for a repairable deteriorating machine. As machine performance can be assessed, once it reaches the maintenance threshold, a maintenance operation is performed to restore the machine. Moreover, an operational cost is introduced to meet real manufacturing process. In this predictive maintenance model, the optimal maintenance threshold and maintenance cycle number are obtained with the aim to minimize the long-term average cost. Finally, a case study is presented. The computational results show the efficiency of this proposed predictive maintenance model. © 2012 Springer-Verlag London Limited.

Lei Y.,Xian Jiaotong University | Lei Y.,Chongqing University | Han D.,Xian Jiaotong University | Lin J.,Xian Jiaotong University | He Z.,Xian Jiaotong University
Mechanical Systems and Signal Processing | Year: 2013

Planetary gearboxes are widely used in aerospace, automotive and heavy industry applications due to their large transmission ratio, strong load-bearing capacity and high transmission efficiency. The tough operation conditions of heavy duty and intensive impact load may cause gear tooth damage such as fatigue crack and teeth missed etc. The challenging issues in fault diagnosis of planetary gearboxes include selection of sensitive measurement locations, investigation of vibration transmission paths and weak feature extraction. One of them is how to effectively discover the weak characteristics from noisy signals of faulty components in planetary gearboxes. To address the issue in fault diagnosis of planetary gearboxes, an adaptive stochastic resonance (ASR) method is proposed in this paper. The ASR method utilizes the optimization ability of ant colony algorithms and adaptively realizes the optimal stochastic resonance system matching input signals. Using the ASR method, the noise may be weakened and weak characteristics highlighted, and therefore the faults can be diagnosed accurately. A planetary gearbox test rig is established and experiments with sun gear faults including a chipped tooth and a missing tooth are conducted. And the vibration signals are collected under the loaded condition and various motor speeds. The proposed method is used to process the collected signals and the results of feature extraction and fault diagnosis demonstrate its effectiveness. © 2012 Elsevier Ltd.

Su X.,Harbin Institute of Technology | Wu L.,Harbin Institute of Technology | Shi P.,University of South Wales | Shi P.,Victoria University of Melbourne | And 2 more authors.
IEEE Transactions on Systems, Man, and Cybernetics, Part B: Cybernetics | Year: 2012

This paper is concerned with the problem of H∞ model reduction for Takagi-Sugeno (T-S) fuzzy stochastic systems. For a given mean-square stable T-S fuzzy stochastic system, our attention is focused on the construction of a reduced-order model, which not only approximates the original system well with an H∞ performance but also translates it into a linear lower dimensional system. Then, the model reduction is converted into a convex optimization problem by using a linearization procedure, and a projection approach is also presented, which casts the model reduction into a sequential minimization problem subject to linear matrix inequality constraints by employing the cone complementary linearization algorithm. Finally, two numerical examples are provided to illustrate the effectiveness of the proposed methods. © 1996-2012 IEEE.

Chen P.S.,CAS National Astronomical Observatories | Yang X.H.,Chongqing University
Astronomical Journal | Year: 2012

Sources with infrared spectra in Group P of the IRAS/LRS database all show polycyclic aromatic hydrocarbon features. They are often planetary nebulae, H II regions, reflection/dark nebulae, Wolf-Rayet stars, or external galaxies. However, we noted that some carbon stars are also included in this group. We searched for and investigated all infrared spectra in Group P of the IRAS/LRS database. Finally, we found 11 previously known carbon stars and identified 8 new candidate carbon stars in Group P. Infrared spectra of these stars may present the 11.2 μm SiC emission features indicative of their carbon-rich properties. © © 2012. The American Astronomical Society. All rights reserved.

Zhao H.-B.,China University of Mining and Technology | Yin G.-Z.,Chongqing University
Yantu Lixue/Rock and Soil Mechanics | Year: 2011

Mechanical properties and acoustic emission characteristics of briquette samples are studied under fixed gas pressure and confining pressure. The results show: mechanical properties discreteness of coal containing gas is decreased because of gas existing; triaxial strength is decreased and Young's modulus is increased compared with coal; acoustic emission events are comparatively well distributed in process of triaxial compression of coal containing gas; the concentrated regions only appear at near damage regions; the distribution of AE events amplitude shows three peaks mode, energy of AE events is increased as deformation increasing; AE events parameters lag behind triaxial compression curve.

Yang B.,Chongqing University | Yang B.,Nanyang Technological University | Tan K.H.,Nanyang Technological University
Engineering Structures | Year: 2013

Several structural collapse incidents indicate that failure usually started from beam-column joints when exposed to abnormal loads. If the connections are sufficiently robust and there is adequate axial restraint from adjoining structures, catenary action usually forms and gives rise to alternate load paths when. affected columns are severely damaged, resulting in large deformations in adjoining beams and slabs. This paper presents seven experimental tests of the performance of common types of bolted steel beam-column joints under a central-column-removal scenario. The joint types including web cleat, top and seat angle, top and seat with web angle (TSWA) (8. mm angle), fin plate, flush end plate, extended end plate and TSWA(12. mm angle) are studied under the central-column-removal scenario. This study provides the behaviour and failure modes of different connections, including their abilities to deform in catenary mode. The test results indicate that the web cleat connection has the best performance in the development of catenary action, and the flush end plate, fin plate and TSWA connections could also deform in a ductile manner and develop catenary action prior to failure. It is worthy to note that tensile capacities of beam-column joints after undergoing large rotations usually control the failure mode and the formation of catenary action. A new tying resistance expression is proposed to consider the effect of large rotation. If large rotation is not considered in the design stage, the joints with poor rotation capacities would fail to achieve the design tying resistances. The test results also demonstrate that the rotation capacities of beam-column joints based on the experimental results in this study were much higher than the recommended values. © 2013 Elsevier Ltd.

Xiang Y.,East China University of Science and Technology | Deng M.,Chongqing University | Xuan F.-Z.,East China University of Science and Technology
Journal of Applied Physics | Year: 2014

The early deformations in materials such as creep, plasticity, and fatigue damages have been proved to have a close relationship with the nonlinear effect of ultrasonic waves propagating in them. In the present paper, a theoretical mesoscale model of an ultrasonic non-destructive method has been proposed to evaluate creep deformed states based on nonlinear guided waves. The model developed here considers the nonlinear generation of Lamb waves response from precipitates variation in the dislocation network, which can be applicable to all precipitate stages including coherent and semi-coherent precipitates in the metallic alloy undergoing creep degradation. To verify the proposed model, experiments of titanium alloy Ti60 plates were carried out with different creep strains. An "increase-decrease" change of the acoustic nonlinearity of guided wave versus the creep life fraction has been observed. Based on microscopic images analyses, the mesoscale model was then applied to these creep damaged Ti60 specimens, which revealed a good accordance with the measured results of the nonlinear guided waves. It is shown that the change of the nonlinear Lamb wave depends on the variations of the α2precipitation volume fraction, the dislocation density, the growth of the creep-voids, and the increasing mismatch of the phase velocities during the creep deformation process. The results indicate that the effect of the precipitate-dislocation interactions on the nonlinear guided wave is likely the dominant mechanism responsible for the change of nonlinear guided wave propagation in the crept materials. © 2014 AIP Publishing LLC.

Yang B.,Chongqing University | Yang B.,Nanyang Technological University | Tan K.H.,Nanyang Technological University
Engineering Structures | Year: 2013

Traditional design of connections is limited to moment-rotation characteristics and the information about the deformation capacities of connection components is quite limited. Thus, it is necessary to develop a new mechanical model, which could predict the deformation capacity of each connection component. In this paper, an experimental investigation of bolted-angle connections under tension is presented. In total, fourteen specimens were tested. The parameters studied in the experiments included bolt hole positions, angle thickness, bolt size and material properties. Depending on the strength ratio between angles and bolts, five types of failure modes were observed in the experimental tests. The test results demonstrated that the load increase at large deformation stage was much higher than the yield strength. Based on the experimental results, a new mechanical model of bolted-angle connections is developed. In the proposed model, the following issues are addressed: (i) the interaction between angles and bolts, (ii) failure criteria to determine the deformation capacities of connection components, and (iii) load limits due to bolt fracture. Finally, the proposed mechanical model is validated by the experimental results and the predictions of the model agree well with the test observations. © 2013 Elsevier Ltd.

Zhang X.-Z.,Chongqing University | Huang P.-K.,China Aerospace Science and Technology Corporation
Xi Tong Gong Cheng Yu Dian Zi Ji Shu/Systems Engineering and Electronics | Year: 2013

A new approach is developed for synthetic aperture radar (SAR) automatic target recognition based on Bayesian compressive sensing (BCS). Firstly SAR images are segmented into image data of target zones by constant false alarm rate. Then based on the BCS model, the sensing matrix is constructed by all training sets. The sparse coefficient vectors corresponding to the test samples are solved. Recognition is performed according to the L2 norm corresponding to each of training types of samples in the sensing matrix. Experimental results with the moving and stationary target acquisition and recognition public dataset show that the proposed approach has good recognition effects.

Li B.,Chongqing Three Gorges University | Li B.,Chongqing University | Yao R.,University of Reading
Building Research and Information | Year: 2012

Rapid urbanization in China has resulted in great demands for energy, resources and pressure on the environment. The progress in China's development is considered in the context of energy efficiency in the built environment, including policy, technology and implementation. The key research challenges and opportunities are identified for delivering a low-carbon built environment. The barriers include the existing traditional sequential design process, the lack of integrated approaches and insufficient socio-technical knowledge. A proposed conceptual systemic model of an integrated approach identifies research opportunities. The organization of research activities should be initiated, operated and managed in a collaborative way among policy-makers, professionals, researchers and stakeholders. More emphasis is needed on integrating social, economic and environmental impacts in the short, medium and long terms. An ideal opportunity exists for China to develop its own expertise, not merely in a technical sense but in terms of vision and intellectual leadership in order to flourish in global collaborations. © 2012 Taylor & Francis.

Adewale I.D.,Northumbria University | Tian G.Y.,Northumbria University | Tian G.Y.,Chongqing University
IEEE Transactions on Magnetics | Year: 2013

Eddy-current (EC) sensors are widely used in the industry for nondestructive evaluation (NDE) and structural health monitoring (SHM). It has this wide acceptance mainly because it has high tolerance to harsh environments, low cost, and high bandwidth. Its variant pulsed eddy current (PEC) provides even more depth information of test materials, which can be applied in liftoff measurement (displacement and coating thickness measurement), defect measurement, and material characterization. However, PEC sensors are prone to measurement errors due to a phenomenon called electrical runout (ERO), which is attributed to the inhomogeneity of the test material. The main thrust of this paper is to investigate, therefore, the contributions of the electromagnetic properties (permeability and conductivity) of the sample to ERO with a view to separate the influence of these two properties. Both time-domain and frequency-domain analyses are carried out in this investigation viz-a-viz: transient response, differential normalized response, magnitude spectrum, and normalized magnitude spectrum. This paper reveals that conductivity effects are prominent in the rising edge of the transient response, hence, changing the spectral pattern in the frequency domain while permeability effects dominate in the stable phase of the transient response, thus this effect can be suppressed or reduced by normalization showing that it is only an amplitude change. © 1965-2012 IEEE.

Xiang D.,Chongqing University | Ran L.,Durham University | Tavner P.,Durham University | Yang S.,University of Warwick | And 2 more authors.
IEEE Transactions on Power Electronics | Year: 2012

Condition monitoring power semiconductor devices can inform converter maintenance and reduce damage. This paper presents a method to monitor solder fatigue in a voltage source inverter insulated gate bipolar transistor power module by detecting the change of an inverter output harmonic. It is shown that low-order harmonics, caused by nonideal switching, are affected by the device junction temperature, which in turn depends upon module solder condition. To improve the detection accuracy of the phenomenon, the inverter controller is set to cause harmonic resonance at the target harmonic frequency. The would-be resonance is suppressed by an outer control loop where the control action can be used as the condition monitoring signal. Simulation and experiment are presented to validate the method and evaluate its performance in operation. © 2011 IEEE.

Wang C.,Chongqing University
International Journal of Electric and Hybrid Vehicles | Year: 2016

As over-charging and over-discharging can cause damage to batteries, to guarantee the stability and duration of batteries, it is necessary to avoid being over-charged and over-discharged. Therefore, knowing the batteries' state of charge (SOC) is essential. In this paper, the author describes in detail the procedure of building a SOC estimation algorithm. The SOC estimation algorithm is based on unscented Kalman filter. Moreover, changes of battery capacity and internal resistance are considered. The impact of these changes on the estimation accuracy is explored. Experiments on an Iron Phosphate Li-ion battery cell with real load were conducted to justify this method. This method was verified to be not only precise but also stable. Copyright © 2016 Inderscience Enterprises Ltd.

Chen G.,Chongqing University | Lewis F.L.,University of Texas at Arlington
Asian Journal of Control | Year: 2012

This paper investigates the distributed tracking control problems for a group of networked mechanical systems. We describe three scenarios that motivate these problems. Firstly, under the conditions that the desired time-varying trajectory is available to a portion of the networked mechanical systems and that the available signals from the neighboring mechanical systems include the position and velocity information, a distributed tracking control strategy is proposed. Next, we remove the requirement for the neighboring mechanical system's velocity information and propose a control method so that the coupling signals among the networked mechanical systems can be only position information. In the third scenario, we assume that only positions are measured for each mechanical system. Distributed nonlinear observers are proposed to estimate the local mechanical system's velocity and acceleration. Based on the estimated states, the distributed controllers are designed to achieve the tracking control. Simulation results are provided to show the effectiveness of the proposed control laws. © 2012 John Wiley and Sons Asia Pte Ltd and Chinese Automatic Control Society.

Chen Z.,Southwest Jiaotong University | Zhu Z.,Nanchang Institute of Technology | Shao Y.,Chongqing University
Engineering Failure Analysis | Year: 2015

Planetary gear transmission has a wide application in different areas due to its advantages such as compactness, large torque-to-weight ratio, reduced noise and vibrations. However, its dynamic responses are much more complex due to the complicated structures and relative motions, which make it difficult in the fault feature extractions at the view point of fault detection. Better understanding on the dynamic features of a planetary gear transmission and the corresponding internal excitation sources will benefit the fault feature extractions. In this paper, an analytical model for mesh stiffness calculation is developed based on the potential energy principle and uniformly curved Timoshenko beam theory, which enables exploring the effects of the tooth root crack fault and the flexible ring gear rim on the dynamic responses. Based on the developed model, the frequency spectrum structures of the planetary gear transmission can be revealed and analyzed theoretically in the presence of tooth crack and flexible ring gear. A case study is performed to demonstrate the effectiveness of the developed model, where the tooth root cracks are seeded in a tooth of the sun, planet, and ring gears. The simulated results indicate that the complicated modulation phenomenon can be observed where the causes of different frequency components can be revealed. This study is expected to be able to give some theoretical guidance on the identification of vibration sources for planetary gear transmissions. © 2015 Elsevier Ltd.

Prabhulkar S.,Florida International University | Piatyszek R.,Florida International University | Cirrito J.R.,Washington University in St. Louis | Wu Z.-Z.,Chongqing University | Li C.-Z.,Florida International University
Journal of Neurochemistry | Year: 2012

Alzheimer's disease (AD) affects about 35.6 million people worldwide, and if current trends continue with no medical advancement, one in 85 people will be affected by 2050. Thus, there is an urgent need to develop a cost-effective, easy to use, sensor platform to diagnose and study AD. The measurement of peptide amyloid beta (Aβ) found in CSF has been assessed as an avenue to diagnose and study the disease. The quantification of the ratio of Aβ1-40/42 (or Aβ ratio) has been established as a reliable test to diagnose AD through human clinical trials. Therefore, we have developed a multiplexed, implantable immunosensor to detect amyloid beta (Aβ) isoforms using triple barrel carbon fiber microelectrodes as the sensor platform. Antibodies act as the biorecognition element of the sensor and selectively capture and bind Aβ1-40 and Aβ1-42 to the electrode surface. Electrochemistry was used to measure the intrinsic oxidation signal of Aβ at 0.65 V (vs. Ag/AgCl), originating from a single tyrosine residue found at position 10 in its amino acid sequence. Using the proposed immunosensor Aβ1-40 and Aβ1-42 could be specifically detected in CSF from mice within a detection range of 20-50 nM and 20-140 nM respectively. The immunosensor enables real-time, highly sensitive detection of Aβ and opens up the possibilities for diagnostic ex vivo applications and research-based in vivo studies. © 2012 The Authors. Journal of Neurochemistry © 2012 International Society for Neurochemistry.

Wei J.,Dalian University of Technology | Zhang G.,Chongqing University
International Journal of Advanced Manufacturing Technology | Year: 2010

Aiming at the high precision machining of screw rotors, a new grinding method for screw rotors using cubic boron nitride (CBN) grinding wheel is presented in this paper. Small electroplated CBN grinding wheel is firstly used to grind screw rotors. The mathematical model for the axial profiles of CBN grinding wheel is developed based on gear engagement theory. Taking the backlash of screw rotors and the coating thickness of CBN layer into consideration, the modification of the base body of the wheel shape is introduced into the design of the CBN grinding wheel. Wire cut electrical discharge machining low speed (WEDM-LS) was used to machine the base body of the CBN grinding wheel. The formed turning tools of the base body of CBN grinding wheel using WEDM-LS and the wheel shapes of CBN grinding wheel using the formed turning tool were performed. The CBN grinding wheels for the screw rotors were made to verify the validity and effectiveness of the presented method. The electroplated CBN grinding wheels were used to machine the screw rotors, and the machining experiments were performed. The data obtained in the experiments reach the fifth class of Chinese Standard GB10095-88. © 2009 Springer-Verlag London Limited.

Ding B.,Chongqing University
IEEE Transactions on Fuzzy Systems | Year: 2010

This paper addresses the stabilization of nonlinear systems, which is represented by a TakagiSugeno (TS) model. Based on the extended nonquadratic Lyapunov function and the nonparallel distributed compensation law, three new results are obtained by using appropriate slack matrices, collection matrices, and the higher dimensional collection matrix. The first two results are less conservative, and computationally less expensive, than some of the existing results. The third result combines the procedures of the first two results, and is less conservative, but is computationally more expensive than the first two results. The effectiveness of the new results is validated by two numerical examples. © 2006 IEEE.

Deng D.,Chongqing University | Kiyoshima S.,Computational Mechanics Inc
Computational Materials Science | Year: 2010

A finite element approach based on Quick Welder software is developed to simulate welding temperature field and welding residual stress distribution in a 3D multi-pass girth-welded pipe model. The characteristics of welding residual stress distributions in a SUS304 stainless steel pipe induced by heating with a tungsten inert gas arc welding torch are investigated numerically. Meanwhile, an emphasis is focused on examining the welding residual stress distributions in and near the weld start/end location. Moreover, the residual stresses predicted by the present computational approach are compared with the measured data; and the comparison suggests that the numerical simulation method has basically captured the feature of welding residual stress distribution near the weld start/end region. The numerical simulation results show that both the hoop and the axial residual stresses near the weld start/end region have sharp gradients and are significantly different from those in the steady range. © 2010 Elsevier B.V. All rights reserved.

Lei G.,Chongqing University | Shixiang L.,Wuhan University
Journal of Convergence Information Technology | Year: 2012

In the study,support vector regression with improved quantum-behaved particle swarm optimization(IQPSO-SVR) is applied to evaluate coal resources demand,and improved quantum-behaved particle swarm optimization(IQPSO) is used to choose the suitable parameters of support vector regression. Firstly,the dimensions of the input vector in the the training sample sets need to be determined and the training sample sets are created.Then, the different IQPSO-SVR models trained by the different training sample sets are generated. The experimental resuts indicate that the IQPSO-SVR model trained by the training sample sets with 4 dimensional input vector has the best evaluation results and the comparison results of the validation and prediction results for coal resources demand between the IQPSO-SVR model and the SVR model show that the evaluation results of the IQPSO-SVR model have better than those of the SVR model.

Tang M.-C.,University of Electronic Science and Technology of China | Tang M.-C.,University of Arizona | Tang M.-C.,Chongqing University | Ziolkowski R.W.,University of Arizona
IEEE Transactions on Antennas and Propagation | Year: 2013

The designs and performance characteristics of several electrically small antennas based on complementary split ring resonators (CSRRs) are reported. A coaxial-fed monopole is first integrated with a CSRR that is cut from a grounded finite copper disc. The presence of the electrically small CSRR element facilitates a nearly complete impedance match to the source, a nearly broadside radiation pattern, and a high radiation efficiency. The addition of a circular top-hat to the monopole then achieves an ultra-low profile (0. 005λ0) design and an improved broadside pattern, while maintaining all other desirable features. Finally, to enrich their potential usefulness, two additional enhancements of these designs were accomplished. One is a further miniaturization (ka < 0.5) that is achieved by introducing a more complex CSRR element, while maintaining a high, 82%, radiation efficiency. The second is a further enhancement of the directivity and front-to-back ratio through the introduction of a slot-modified parasitic disc, while maintaining the original impedance matching, low-profile and electrically small properties. These designs were consummated and their performance characteristics evaluated with the frequency domain ANSYS-ANSOFT High Frequency Structure Simulator (HFSS) and were confirmed independently using the time domain CST Microwave Studio (MWS) simulator. A prototype of the basic system was fabricated and tested; the agreement between the simulated and measured results validates the design principles. © 1963-2012 IEEE.

Tao Y.,Chongqing University
Physical Review E - Statistical, Nonlinear, and Soft Matter Physics | Year: 2010

The origin of economic crises is a key problem for economics. We present a model of long-run competitive markets to show that the multiplicity of behaviors in an economic system, over a long time scale, emerge as statistical regularities (perfectly competitive markets obey Bose-Einstein statistics and purely monopolistic-competitive markets obey Boltzmann statistics) and that how interaction among firms influences the evolutionary of competitive markets. It has been widely accepted that perfect competition is most efficient. Our study shows that the perfectly competitive system, as an extreme case of competitive markets, is most efficient but not stable, and gives rise to economic crises as society reaches full employment. In the economic crisis revealed by our model, many firms condense (collapse) into the lowest supply level (zero supply, namely, bankruptcy status), in analogy to Bose-Einstein condensation. This curious phenomenon arises because perfect competition (homogeneous competitions) equals symmetric (indistinguishable) investment direction, a fact abhorred by nature. Therefore, we urge the promotion of monopolistic competition (heterogeneous competitions) rather than perfect competition. To provide early warning of economic crises, we introduce a resolving index of investment, which approaches zero in the run-up to an economic crisis. On the other hand, our model discloses, as a profound conclusion, that the technological level for a long-run social or economic system is proportional to the freedom (disorder) of this system; in other words, technology equals the entropy of system. As an application of this concept, we give a possible answer to the Needham question: "Why was it that despite the immense achievements of traditional China it had been in Europe and not in China that the scientific and industrial revolutions occurred?" © 2010 The American Physical Society.

Zhang C.,Sun Yat Sen University | Huang L.,Chongqing University
Physica A: Statistical Mechanics and its Applications | Year: 2010

Beginning with several basic hypotheses of quantum mechanics, we give a new quantum model in econophysics. In this model, we define wave functions and operators of the stock market to establish the Schrdinger equation for stock price. Based on this theoretical framework, an example of a driven infinite quantum well is considered, in which we use a cosine distribution to simulate the state of stock price in equilibrium. After adding an external field into the Hamiltonian to analytically calculate the wave function, the distribution and the average value of the rate of return are shown. © 2010 Elsevier B.V. All rights reserved.

Lin K.,Chongqing University
International Journal of Theoretical Physics | Year: 2010

We research gravitational perturbation of Garfinkle-Horowitz-Strominger dilaton black hole and its quasinormal modes by using WKB approach proposed by Schutz, Will, Iyer and Konoplya. The quasinormal frequency with different angular momentum l is calculated in this paper. Our results show that, as the charge parameter b increase, both the real part and the absolute value of imaginary part of quasinormal frequency also increase, which means that the effect of charge in Garfinkle-Horowitz-Strominger dilaton background spacetime lead to higher frequency gravitational wave and the quasinormal modes damp at a rapider rate. © 2010 Springer Science+Business Media, LLC.

Zhao J.,University of Akron | Yu X.,University of Akron | Liang G.,University of Akron | Liang G.,Chongqing University | Zheng J.,University of Akron
Biomacromolecules | Year: 2011

A 37-residue of human islet amyloid polypeptide (hIAPP or amylin) is a main component of amyloid plaques found in the pancreas of ∼90% of type II diabetes patients. It is reported that hIAPP oligomers, rather than mature fibrils, are major toxic species responsible for pancreatic islet β-cell dysfunction and even cell death, but molecular structures of these oligomers remain elusive. In this work, on the basis of recent solid-state NMR and mass-per-length (MPL) data, we model a series of hIAPP oligomers with different β-layers (one, two, and three layers), symmetries (symmetry and asymmetry), and associated interfaces using molecular dynamics simulations. Three distinct interfaces formed by C-terminal β-sheet and C-terminal β-sheet (CC), N-terminal β-sheet and N-terminal β-sheet (NN), and C-terminal β-sheet and N-terminal β-sheet (CN) are identified to drive multiple cross-β-layers laterally associated together to form different amyloid organizations via different intermolecular interactions, in which the CC interface is dominated by polar interactions, the NN interface is dominated by hydrophobic interactions, and the CN interface is dominated by mixed polar and hydrophobic interactions. Overall, the structural stability of the proposed hIAPP oligomers is a result of delicate balance between maximization of favorable peptide-peptide interactions at the interfaces and optimization of solvation energy with globular structure. Different hIAPP oligomeric models indicate a general and intrinsic nature of amyloid polymorphism, driven by different interfacial side-chain interactions. The proposed models are compatible with recent experimental data in overall size, cross-section area, and molecular weight. A general hIAPP aggregation mechanism is proposed on the basis of our simulated models and experimental data. © 2010 American Chemical Society.

Residual tensile stresses often increase the susceptibility to cold cracking, and also promote brittle fracture, fatigue failure, and stress corrosion cracking in combination with tensile stresses experienced during service. Welding-induced deformation usually degrades the performance of a structure. Thus, the control of welding residual stress and distortion is a crucial task in welding manufacturing. There are too many factors that affect welding residual stresses and distortion. Besides material properties and design-related parameters, the welding procedures such as deposition sequence and assembly sequence also have significant influence on the final residual stress distribution and deformation. In this study, a computational approach based on Quick Welder software was developed to simulate the welding temperature field, residual stress distribution and deformation in multi-pass joints. The main objective was to clarify the influence of deposition sequence on the final residual stress distribution and deformation in an austenitic stainless steel tube-block joint with J-groove. The simulation results indicate that deposition sequence not only significantly affects the distribution of residual stress but also can alter the deformation mode to a certain extent. In addition, it was found that the last weld pass seems to have the largest contribution to the final welding residual stress filed of current tube-block joint. © 2013 Elsevier Ltd.

Xu W.,University of Alberta | Yong J.,Chongqing University
Zhongguo Dianji Gongcheng Xuebao/Proceedings of the Chinese Society of Electrical Engineering | Year: 2013

Power quality is a field that deals with all sorts of power disturbances. Past power quality research and development activities have been focused on the harmful aspects of the disturbances. With the wide spread use of power quality monitoring tools, more and more users and developers start to realize that power disturbances can carry valuable information about the conditions of a system and its equipment. As a result, initiatives that explore the "useful" aspects of power disturbances have emerged. For example, short-circuit caused voltage sag disturbances have been exploited for fault location purposes and characteristics of capacitor-switching transients are used to determine which feeder capacitors are operating normally. Such "positive" use of power disturbance data and monitoring techniques is becoming an important field of the future smart grid. This field is also closely related to the massive trend of "data analytics" research, development and application. Here we may call the field "power disturbance data analytics". The objective of this paper is to present some of the example developments in this emerging field. We hope this survey/review paper will help to stir up broader research interests in the field and serves as a step stone for power quality researchers. © 2013 Chinese Society for Electrical Engineering.

Kucukkoc I.,University of Exeter | Kucukkoc I.,Balikesir University | Zhang D.Z.,University of Exeter | Zhang D.Z.,Chongqing University
International Journal of Production Economics | Year: 2014

One of the key factors of a successfully implemented mixed-model line system is considering model sequencing problem as well as the line balancing problem. In the literature, there are many studies, which consider these two tightly interrelated problems individually. However, we integrate the model sequencing problem in the line balancing procedure to obtain a more efficient solution for the problem of Simultaneous Balancing and Sequencing of Mixed-Model Parallel Two-Sided Assembly Lines. A mathematical model is developed to present the problem and a novel agent based ant colony optimisation approach is proposed as the solution method. Different agents interact with each other to find a near optimal solution for the problem. Each ant selects a random behaviour from a predefined list of heuristics and builds a solution using this behaviour as a local search rule along with the pheromone value. Different cycle times are allowed for different two-sided lines located in parallel to each other and this yields a complex problem where different production cycles need to be considered to build a feasible solution. The performance of the proposed approach is tested through a set of test cases. Experimental results indicate that considering model sequencing problem with the line balancing problem together helps minimise line length and total number of required workstations. Also, it is found that the proposed approach outperforms other three heuristics tested. © 2014 Elsevier B.V. All rights reserved.

Zuojun P.,Chongqing University
Journal of Convergence Information Technology | Year: 2012

In the study, a hybrid model of support vector machine and Gaussian quantum particle swarm optimization algorithm (GQPSO-SVM) is applied to land transaction price index forecasting, Gaussian quantum particle swarm optimization algorithm is used to optimize the parameters of support vector machine. Gaussian quantum particle swarm optimization algorithm has a better global optimization ability than particle swarm optimization algorithm. The land transaction price index data of China are used as experimental data to analyze the land transaction price index forecasting ability of a SVM and quantum PSO hybrid algorithm. It is indicated that the prediction results for land transaction price index of the GQPSO-SVM model with 2~6 input nodes are better than those of the SVM model with 2~6 input nodes.

Fang S.-M.,Chongqing University | Fang S.-M.,China West Normal University
Bulletin of Insectology | Year: 2012

Glutathione S-transferases (GSTs) are a superfamily of multifunctional enzymes, widely distributed in living organisms. Recently, more and more insect genome sequences are available. Genomic characterizations and comparative analyses of insect GSTs have been performed. In addition, application of high-throughput technologies, such as microarray and next-generation sequencing technology, have accelerated the identification of inducible and resistant GSTs. In this review, we mainly discussed the progress in comparative genomic analysis of insect GSTs and identification of inducible and resistant GSTs using the high-throughput technologies.

Yang J.,Georgia Institute of Technology | Yang J.,Chongqing University | Chen J.,Georgia Institute of Technology | Liu Y.,Georgia Institute of Technology | And 4 more authors.
ACS Nano | Year: 2014

As a vastly available energy source in our daily life, acoustic vibrations are usually taken as noise pollution with little use as a power source. In this work, we have developed a triboelectrification-based thin-film nanogenerator for harvesting acoustic energy from ambient environment. Structured using a polytetrafluoroethylene thin film and a holey aluminum film electrode under carefully designed straining conditions, the nanogenerator is capable of converting acoustic energy into electric energy via triboelectric transduction. With an acoustic sensitivity of 9.54 V Pa-1 in a pressure range from 70 to 110 dB and a directivity angle of 52°, the nanogenerator produced a maximum electric power density of 60.2 mW m-2, which directly lit 17 commercial light-emitting diodes (LEDs). Furthermore, the nanogenerator can also act as a self-powered active sensor for automatically detecting the location of an acoustic source with an error less than 7 cm. In addition, an array of devices with varying resonance frequencies was employed to widen the overall bandwidth from 10 to 1700 Hz, so that the nanogenerator was used as a superior self-powered microphone for sound recording. Our approach presents an adaptable, mobile, and cost-effective technology for harvesting acoustic energy from ambient environment, with applications in infrastructure monitoring, sensor networks, military surveillance, and environmental noise reduction. © 2014 American Chemical Society.

Zhang W.,Henan Institute of Science and Technology | Wang M.,Chongqing University | Zhao W.,Henan Institute of Science and Technology | Wang B.,Henan Institute of Science and Technology
Dalton Transactions | Year: 2013

Magnetic composite ZnFe2O4/BiVO4 was successfully synthesized by the one-step chemical coprecipitation method. The photocatalytic activity of BiVO4 was improved by doping ZnFe 2O4 that possessed a narrow band gap, which enabled the ZnFe2O4/BiVO4 composite to show increased visible-light absorption and further generate more photo-produced electrons than pure BiVO4. The experimental results showed that the photocatalytic ability of the composite was better than that of pure BiVO4 under visible light irradiation. The n-type ZnFe2O4 nanoparticles were uniformly distributed on the surface of n-type BiVO 4, leading to the formation of n-n-type heterogeneous structures in the composite system. Since CB and VB potentials of ZnFe2O 4 and BiVO4 were differential, the photo-produced electrons and holes would migrate to a position at a relatively positive potential and a relatively negative potential, respectively, which enhanced the separation efficiency between photo-produced electrons and holes and thus further contributed to the enhancement of photocatalytic activity. © 2013 The Royal Society of Chemistry.

Xiang Y.,East China University of Science and Technology | Deng M.,Chongqing University | Xuan F.-Z.,East China University of Science and Technology | Liu C.-J.,East China University of Science and Technology
NDT and E International | Year: 2011

The thermal degradation in ferritic CrNi alloy steel plates is measured using the nonlinear effect of Lamb wave propagation. Experiments were carried out to introduce controlled levels of thermal damage to determine the nonlinear response of Lamb waves. A mountain-shape change in the normalized acoustic nonlinearity of Lamb wave versus the level of thermal degradation in the specimens has been observed. The variation in the measured acoustic nonlinearity reveals, based on metallographic studies, that the normalized acoustic nonlinearity increases due to the second phase precipitates in the early stage and it decreases as a combined result of dislocation change and micro-void initiation in the material. The results show a potential application of the nonlinear Lamb waves for the quantitative assessment of thermal damage in metallic plates or pipes. © 2011 Elsevier Ltd. All Rights Reserved.

Li B.,Mississippi State University | Zhang X.Y.,Chongqing University
Scripta Materialia | Year: 2014

Recent experimental observations have revealed that {101̄2} <101̄1̄> twinning involves zero shear, confirming this twinning mode is dominated by shuffling rather than shear. This raises the question: how is global strain generated by shuffling in hexagonal close-packed metals without involving shear? This paper addresses this important question. We demonstrate that although shuffling does not contribute to the twinning shear, it generates a normal strain along the c-axis due to the misfit between the parent and the twin lattice. © 2013 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Hu Y.,Georgia Institute of Technology | Hu Y.,Peking University | Yang J.,Georgia Institute of Technology | Yang J.,Chongqing University | And 4 more authors.
ACS Nano | Year: 2014

The recently introduced triboelectric nanogenerator (TENG) and the traditional electromagnetic induction generator (EMIG) are coherently integrated in one structure for energy harvesting and vibration sensing/isolation. The suspended structure is based on two oppositely oriented magnets that are enclosed by hollow cubes surrounded with coils, which oscillates in response to external disturbance and harvests mechanical energy simultaneously from triboelectrification and electromagnetic induction. It extends the previous definition of hybrid cell to harvest the same type of energy with multiple approaches. Both the sliding-mode TENG and contact-mode TENG can be achieved in the same structure. In order to make the TENG and EMIG work together, transformers are used to match the output impedance between these two power sources with very different characteristics. The maximum output power of 7.7 and 1.9 mW on the same load of 5 kΩ was obtained for the TENG and EMIG, respectively, after impedance matching. Benefiting from the rational design, the output signal from the TENG and the EMIG are in phase. They can be added up directly to get an output voltage of 4.6 V and an output current of 2.2 mA in parallel connection. A power management circuit was connected to the hybrid cell, and a regulated voltage of 3.3 V with constant current was achieved. For the first time, a logic operation was carried out on a half-adder circuit by using the hybrid cell working as both the power source and the input digit signals. We also demonstrated that the hybrid cell can serve as a vibration isolator. Further applications as vibration dampers, triggers, and sensors are all promising. © 2014 American Chemical Society.

Chen S.-G.,Chongqing University
International Journal of Advancements in Computing Technology | Year: 2012

In order to improve the efficiency of association rule mining, this paper proposes an efficient spatial association rule mining algorithm based on region, which takes the spatial constraints into account to filter irrelevant data quickly and improve the efficiency of discovering spatial association rule. The proposed algorithm analyzes the spatial relativity during the generation of frequency item sets and calculates support and confidence by the numeric parsers. Experiments results show that the proposed algorithm can improve the accuracy of spatial association rule mining greatly.

Gu F.,University of Huddersfield | Shao Y.,Chongqing University | Hu N.,National University of Defense Technology | Naid A.,University of Huddersfield | Ball A.D.,University of Huddersfield
Mechanical Systems and Signal Processing | Year: 2011

This paper presents the use of the induction motor current to identify and quantify common faults within a two-stage reciprocating compressor based on bispectrum analysis. The theoretical basis is developed to understand the nonlinear characteristics of current signals when the motor undertakes a varying load under different faulty conditions. Although conventional bispectrum representation of current signal allows the inclusion of phase information and the elimination of Gaussian noise, it produces unstable results due to random phase variation of the sideband components in the current signal. A modified bispectrum based on the amplitude modulation feature of the current signal is then adopted to combine both lower sidebands and higher sidebands simultaneously and hence characterise the current signal more accurately. Based on this new bispectrum analysis a more effective diagnostic feature, namely normalised bispectral peak, is developed for fault classification. In association with the kurtosis value of the raw current signal, the bispectrum feature gives rise to reliable fault classification results. In particular, the low feature values can differentiate the belt looseness from the other fault cases and different degrees of discharge valve leakage and inter-cooler leakage can be separated easily using two linear classifiers. This work provides a novel approach to the analysis of stator current for the diagnosis of motor drive faults from downstream driving equipment. © 2010 Published by Elsevier Ltd. All rights reserved.

Chen C.,Chongqing University
Oxidative Medicine and Cellular Longevity | Year: 2016

Sinapic acid (3,5-dimethoxy-4-hydroxycinnamic acid) is an orally bioavailable phytochemical, extensively found in spices, citrus and berry fruits, vegetables, cereals, and oilseed crops and is known to exhibit antioxidant, anti-inflammatory, anticancer, antimutagenic, antiglycemic, neuroprotective, and antibacterial activities. The literature reveals that sinapic acid is a bioactive phenolic acid and has the potential to attenuate various chemically induced toxicities. This minireview is an effort to summarize the available literature about pharmacokinetic, therapeutic, and protective potential of this versatile molecule in health related areas. © 2016 Chunye Chen.

Wen L.,Chongqing University | Bi X.T.,University of British Columbia
Powder Technology | Year: 2011

A method has been developed to deduce a "breakup" force in a packed bed based on measured pressure drop and internal cavity size hysteresis data in a conical spouted bed. The pressure drop over the vertical jet is estimated by the Eulerian-Eulerian two-fluid model using the commercial Fluent software. The pressure drop over the packed bed is extracted from the measured total pressure drop following a flow rate descending process in the spouted bed, while the "breakup" force is determined from the combination of measured total pressure drop and internal jet height following the flow ascending process, the simulated pressure drop over the gas jet and the pressure drop over the loosely packed upper bed section. Such a proposed method can be applied in the future to develop a generalized expression for the "breakup" force in spouted beds and other packed bed systems where a vertical fluid jet is issued into the packed particles. © 2010 Elsevier B.V.

Yang L.-P.,Chongqing University | Gu X.-H.,Chongqing University of Science and Technology
Guangxue Jingmi Gongcheng/Optics and Precision Engineering | Year: 2014

As Pattern of Oriented Edge Magnitude (POEM) method can not acquire enough feature description information in illumination condition changes drastically, this paper analyzes the characteristic of relative gradient magnitude images and proposes a Relative Gradient Histogram Feature(RGHF) description method. The method decomposes the relative gradient magnitude image into several sub images according to the orientations of gradient. Each of these sub images is then filtered and encoded by using Local Binary Patterns(LBPs). Finally, all the encoded LBP histogram features are connected by a lexicographic ordering and are reduced to a low-dimensional subspace to form the RGHF, which is an illumination robust low-dimensional histogram feature. Experimental results on FERET and YaleB subsets indicate when the illumination variation is relative small, the recognition performance of the RGHF is comparable with that of the POEM, superior to that of the LBP significantly. Moreover, when the illumination variation is drastic, the recognition performance of RGHF is at least 5% higher than that of the POEM, more better than those of the POEM and LBP.

Fan H.,Yangtze Normal University | Zhong Y.,Chongqing University
Journal of Computational Information Systems | Year: 2012

As an important concept of rough set theory, an attribute reduction is a subset of attributes that are jointly sufficient and individually necessary for preserving a particular property of the given information table. In order to acquire minimal attribute reduction, we propose a wasp swarm optimization algorithm for attribute reduction based on rough set and the significance of feature. The significance of feature is constructed based on the mutual information between selected conditional attributes and decisional attributes. The algorithm dynamically calculates heuristic information based on the significance of feature to guide search. Experimental are carried out on some standard UCI datasets. The results demonstrate that, in terms of solution quality and computational effort, proposed algorithm can get better results than other intelligent swarm algorithms for attribute reduction. 1553-9105/Copyright © 2012 Binary Information Press.

Xin Y.,Chongqing University | Hu T.,City University of Hong Kong | Chu P.K.,City University of Hong Kong
Corrosion Science | Year: 2011

Corrosion behaviour of pure magnesium in simulated body fluids (SBF) with HCO3 - concentrations of 4, 15 and 27mmol/L is studied. Magnesium is not sensitive to pitting corrosion in all the SBFs. Higher HCO3 - concentration effectively slow down the corrosion rates. Uniform and compact corrosion product layer preferentially forms in SBF with HCO3 - of 27mmol/L. Potentiodynamic polarization test indicates that HCO3 - of 27mmol/L dramatically enhance corrosion potential and induce passivation. EIS results further confirm that higher concentration of HCO3 - induce more effective protection layer, especially in SBF with HCO3 - of 27mmol/L. © 2011 Elsevier Ltd.

Berglund S.P.,University of Texas at Austin | He H.,University of Texas at Austin | He H.,Chongqing University | Chemelewski W.D.,University of Texas at Austin | And 3 more authors.
Journal of the American Chemical Society | Year: 2014

p-Si/W2C photocathodes are synthesized by evaporating tungsten metal in an ambient of ethylene gas to form tungsten semicarbide (W 2C) thin films on top of p-type silicon (p-Si) substrates. As deposited the thin films contain crystalline W2C with a bulk W:C atomic ratio of approximately 2:1. The W2C films demonstrate catalytic activity for the hydrogen evolution reaction (HER), and p-Si/W 2C photocathodes produce cathodic photocurrent at potentials more positive than 0.0 V vs RHE while bare p-Si photocathodes do not. The W 2C films are an effective support for Pt nanoparticles allowing for a considerable reduction in Pt loading. p-Si/W2C/Pt photocathodes with Pt nanoparticles achieve photocurrent onset potentials and limiting photocurrent densities that are comparable to p-Si/Pt photocathodes with Pt loading nine times higher. This makes W2C an earth abundant alternative to pure Pt for use as an electrocatalyst on photocathodes for the HER. © 2014 American Chemical Society.

Guan X.-W.,CAS Wuhan Institute of Physics and Mathematics | Guan X.-W.,Australian National University | Batchelor M.T.,Australian National University | Batchelor M.T.,Chongqing University | And 2 more authors.
Reviews of Modern Physics | Year: 2013

This article reviews theoretical and experimental developments for one-dimensional Fermi gases. Specifically, the experimentally realized two-component delta-function interacting Fermi gas - the Gaudin-Yang model - and its generalizations to multicomponent Fermi systems with larger spin symmetries is discussed. The exact results obtained for Bethe ansatz integrable models of this kind enable the study of the nature and microscopic origin of a wide range of quantum many-body phenomena driven by spin population imbalance, dynamical interactions, and magnetic fields. This physics includes Bardeen-Cooper- Schrieffer-like pairing, Tomonaga-Luttinger liquids, spin-charge separation, Fulde-Ferrel-Larkin-Ovchinnikov-like pair correlations, quantum criticality and scaling, polarons, and the few-body physics of the trimer state (trions). The fascinating interplay between exactly solved models and experimental developments in one dimension promises to yield further insight into the exciting and fundamental physics of interacting Fermi systems. © 2013 American Physical Society.

Huang R.,Chengdu University of Technology | Huang D.,Chengdu University of Technology | Huang D.,Chongqing University
Yanshilixue Yu Gongcheng Xuebao/Chinese Journal of Rock Mechanics and Engineering | Year: 2010

The mechanical properties of rocks are obviously affected by initial stress state and unloading rates that are caused by excavation. Based on triaxial unloading and scanning electron microscopy(SEM) analysis, the deformation, breakage, and strength features of marble samples of the Jinping First Hydropower Station under different unloading rates and geostress conditions are studied. With unloading rates vu and initial confining pressure σ3 0 increasing, the brittle rupture and tensile characteristics of rock are more obvious. There are annular tensile cracks in secondary unloading direction when the rock samples are unloaded in two directions; and the meso-shapes of the tensile fracture surface under SEM consequently are presented with branch-tension, and multilayer biscuit-lancinated and slippery plane-ejected shapes. The axial strain compression increment Δε1 is gradually reduced, but the confining expansion stress Δε3 is increased during the process of unloading. The influence of unloading rate vu on deformation modulus E is different at the different deformation stages during process of unloading. The deformation modulus E is gradually increased before peak strength, but it gradually increases firstly and rapidly decreases afterward with vu enhanced. The Poisson s ratio μ is gradually increased during process of unloading, and it is more distinct with vu and σ3 0 enhancing, especially after peak strength. Relative to data of traditional triaxial loading test, the rock cohesion c is remarkably reduced but inner friction angle ψ is a little increased under unloading test. The faster the vu is, the more c is reduced, and the less the ψ increases.

Su L.,University of Connecticut | Jia W.,University of Connecticut | Hou C.,Chongqing University | Lei Y.,University of Connecticut
Biosensors and Bioelectronics | Year: 2011

A microbial biosensor is an analytical device which integrates microorganism(s) with a physical transducer to generate a measurable signal proportional to the concentration of analytes. In recent years, a large number of microbial biosensors have been developed for environmental, food, and biomedical applications. Starting with the discussion of various sensing techniques commonly used in microbial biosensing, this review article concentrates on the summarization of the recent progress in the fabrication and application of microbial biosensors based on amperometry, potentiometry, conductometry, voltammetry, microbial fuel cell, fluorescence, bioluminescence, and colorimetry, respectively. Prospective strategies for the design of future microbial biosensors will also be discussed. © 2010 .

Zheng S.,Chongqing University
Nuclear Physics B | Year: 2013

Bounds on anomalous dimensions of scalar operators in 4D superconformal field theory are explored through perturbative viewpoint. Following the recent work of Green and Shih, in which a conjecture involved this issue is verified at the NLO, we consider the NNLO corrections to the bounds, which are important in some situations and can be divided into two cases where O(λ4) or O(y2) effects dominate respectively. In the former case, we find that the conjecture is maintained at NNLO, while in the later case the statement still holds due to null correction. © 2013 Elsevier B.V.

Zhou S.,Chongqing Normal University | Mu C.,Chongqing University
Journal of Nonlinear Science | Year: 2013

This paper deals with the Cauchy problem for a shallow water equation with high-order nonlinearities, y t +u m+1 y x +bu m u x y=0, where b is a constant, m∈ N, and we have the notation y:= (1-∂x 2) u, which includes the famous Camassa-Holm equation, the Degasperis-Procesi equation, and the Novikov equation as special cases. The local well-posedness of strong solutions for the equation in each of the Sobolev spaces Hs(R) with s>3/2 is obtained, and persistence properties of the strong solutions are studied. Furthermore, although the H1(R)-norm of the solution to the nonlinear model does not remain constant, the existence of its weak solutions in each of the low order Sobolev spaces Hs(R) with 1

This study presents a blind carrier frequency offset (CFO) tracking algorithm for orthogonal frequency division multiplexing systems with constant modulus signalling. Both single-input single-output and multiple-input multiple-output (MIMO) systems are considered. Based on the assumption that the channel frequency response (CFR) has been estimated by training symbols and keeps constant over one frame duration, we discover that the CFO can be estimated via minimising the power difference between the received signals and the CFR. The polynomial rooting method is exploited to derive a low complexity solution. The expectation and mean-square error of the proposed method are derived mathematically. Besides, the effect of channel estimation error on the performance of CFO tracking is addressed and it is shown that the proposed algorithm is robust to this error. At last, this blind scheme can be applied to a MIMO system with the aid of space time block codes. © 2012 The Institution of Engineering and Technology.

He X.,Chongqing University | Li C.,Chongqing University | Huang T.,Texas A&M University at Qatar | Li C.,University of Ballarat
Nonlinear Analysis: Real World Applications | Year: 2013

In this paper, a delayed neural network model with unidirectional coupling is considered. Zero-Hopf bifurcation is studied by using the center manifold reduction and the normal form method for retarded functional differential equation. We get the versal unfolding of the norm form at the zero-Hopf singularity and show that the model can exhibit pitchfork, Hopf bifurcation, and double Hopf bifurcation is also found to occur in this model. Some numerical simulations are given to support the analytic results. © 2012 Elsevier Ltd. All rights reserved.

Su X.,Harbin Institute of Technology | Shi P.,University of South Wales | Shi P.,Victoria University of Melbourne | Shi P.,University of South Australia | And 2 more authors.
IEEE Transactions on Fuzzy Systems | Year: 2012

In this paper, the problem of l2-l? filtering for a class of discrete-time Takagi-Sugeno (T-S) fuzzy time-varying delay systems is studied. Our attention is focused on the design of full-and reduced-order filters that guarantee the filtering error system to be asymptotically stable with a prescribed H? performance. Sufficient conditions for the obtained filtering error system are proposed by applying an input-output approach and a two-term approximation method, which is employed to approximate the time-varying delay. The corresponding full-and reduced-order filter design is cast into a convex optimization problem, which can be efficiently solved by standard numerical algorithms. Finally, simulation examples are provided to illustrate the effectiveness of the proposed approaches. © 2012 IEEE.

Deng D.,Chongqing University | Murakawa H.,Osaka University | Ma N.,Osaka University
Science and Technology of Welding and Joining | Year: 2012

In this study, welding distortion in a large thin plate panel structure was predicted by means of elastic finite element method based on inherent strain theory and interface element formulation. The welding distortions in the thin plate model computed by large deformation theory and small deformation theory were compared. The comparison suggests that the geometrical non-linearity should be carefully considered when welding distortion in a thin plate structure is predicted. In addition, the influences of welding procedure and assembly sequence on the final distortion were examined numerically. Simulation results indicate that both welding procedure and assembly sequence significantly affect the final deformation. © 2012 Institute of Materials, Minerals and Mining.

Liu M.,Chongqing University | Chiang K.S.,City University of Hong Kong
Applied Physics B: Lasers and Optics | Year: 2010

We analyze the propagation of ultrashort pulses in a nonlinear two-core photonic crystal fiber (PCF) by solving a pair of coupled-mode equations that include all the significant linear and nonlinear terms. In particular, we highlight the fact that the coupling coefficient dispersion can cause significant pulse distortion over a short length of a two-core PCF. We also study all-optical switching and multi-frequency generation and obtain a reasonable agreement with recent experimental data. © 2009 Springer-Verlag.

Xiao D.,Chongqing University | Xiao D.,New Jersey Institute of Technology | Shih F.Y.,New Jersey Institute of Technology
Optics Communications | Year: 2010

In this paper, we analyze the problems of vulnerability in the original multi chaotic systems-based image encryption scheme proposed by Huang and Nien [Optics Communications 282(2009) 2123-2127]. A selfsynchronizing method is proposed as enhancement measures to solve the problems and defeat cryptanalysis. Theoretical analysis and computer simulation indicate that the proposed encryption scheme is much more secure than the original one. At the same time, it holds the merits of the original scheme. © 2010 Elsevier B.V.

Li X.,Wilfrid Laurier University | Li X.,Chongqing University | Ghose S.,Wilfrid Laurier University | Ghose S.,University of Waterloo
Laser Physics Letters | Year: 2014

We present a hyperconcentration scheme for nonlocal N-photon hyperentangled Greenberger-Horne-Zeilinger states. The maximally hyperentangled state, in which N particles are entangled simultaneously in the polarization and the spatial mode, can be obtained with a certain probability from two partially hyperentangled states. The hyperconcentration scheme is based on one polarization parity check measurement, one spatial mode parity check measurement and N - 2 single-photon two-qubit measurements. The concentration only requires linear optical elements, which makes it feasible and practical with current technology. © 2014 Astro Ltd.

Brodsky S.J.,SLAC | Wu X.-G.,SLAC | Wu X.-G.,Chongqing University
Physical Review D - Particles, Fields, Gravitation and Cosmology | Year: 2012

The renormalization scale uncertainty can be eliminated by the principle of maximum conformality (PMC) in a systematic, scheme-independent way. Applying the PMC for the tt̄-pair hadroproduction at the next-to-next-to-leading- order level, we have found that the total cross sections σ tt̄ at both the Tevatron and LHC remain almost unchanged when taking very disparate initial scales μRinit equal to m t, 10m t, 20m t and √s, which is consistent with renormalization group invariance. As an important new application, we apply PMC scale setting to study the top quark forward-backward asymmetry. We observe that the more convergent perturbative series after PMC scale-setting leads to a more accurate top quark forward-backward asymmetry. The resulting PMC prediction on the asymmetry is also free from the initial renormalization scale dependence. Because the next-to-leading-order PMC scale has a dip behavior for the (qq̄) channel at small subprocess collision energies, the importance of this channel to the asymmetry is increased. We observe that the asymmetries AFBtt̄ and AFBpp̄ at the Tevatron will be increased by 42% in comparison to the previous estimates obtained by using conventional scale setting; i.e., we obtain AFBtt̄,PMC12.5% and AFBpp̄,PMC8.28%. Moreover, we obtain AFBtt̄,PMC(M tt̄>450GeV)35.0%. These predictions have a 1σ deviation from the present CDF and D0 measurements; the large discrepancies of the top quark forward-backward asymmetry between the standard model estimate and the CDF and D0 data are thus greatly reduced. © 2012 American Physical Society.

Brodsky S.J.,SLAC | Wu X.-G.,SLAC | Wu X.-G.,Chongqing University
Physical Review D - Particles, Fields, Gravitation and Cosmology | Year: 2012

A key problem in making precise perturbative QCD predictions is to set the proper renormalization scale of the running coupling. The extended renormalization group equations, which express the invariance of the physical observables under both the renormalization scale- and scheme-parameter transformations, provide a convenient way for estimating the scale- and scheme-dependence of the physical process. In this paper, we present a solution for the scale equation of the extended renormalization group equations at the four-loop level. Using the principle of maximum conformality (PMC)/Brodsky-Lepage-Mackenzie (BLM) scale-setting method, all nonconformal {β i} terms in the perturbative expansion series can be summed into the running coupling, and the resulting scale-fixed predictions are independent of the renormalization scheme. The PMC/BLM scales can be fixed order-by-order. As a useful reference, we present a systematic and scheme-independent procedure for setting PMC/BLM scales up to next-to-next-to-leading order. An explicit application for determining the scale setting of R e+e-(Q) up to four loops is presented. By using the world average αsMS̄(M Z)=0. 1184±0.0007, we obtain the asymptotic scale for the 't Hooft scheme associated with the MS̄ scheme, ΛMS̄′tH=245-10+9MeV, and the asymptotic scale for the conventional MS̄ scheme, Λ MS̄=213-8+19MeV. © 2012 American Physical Society.

Tao Y.,Chongqing University
Communications in Theoretical Physics | Year: 2012

In this paper, we attempt to give a sufficient condition of guaranteeing the validity of the proof of the quantum adiabatic theorem. The new sufficient condition can clearly remove the inconsistency and the counterexample of the quantum adiabatic theorem pointed out by Marzlin and Sanders [Phys. Rev. Lett. 93 (2004) 160408]. © 2012 Chinese Physical Society and IOP Publishing Ltd.

Brodsky S.J.,SLAC | Wu X.-G.,SLAC | Wu X.-G.,Chongqing University
Physical Review D - Particles, Fields, Gravitation and Cosmology | Year: 2012

In conventional treatments, predictions from fixed-order perturbative QCD calculations cannot be fixed with certainty because of ambiguities in the choice of the renormalization scale as well as the renormalization scheme. In this paper we present a general discussion of the constraints of the renormalization group (RG) invariance on the choice of the renormalization scale. We adopt the RG-based equations, which incorporate the scheme parameters, for a general exposition of RG invariance, since they simultaneously express the invariance of physical observables under both the variation of the renormalization scale and the renormalization scheme parameters. We then discuss the self-consistency requirements of the RG, such as reflexivity, symmetry, and transitivity, which must be satisfied by the scale-setting method. The principle of minimal sensitivity requires the slope of the approximant of an observable to vanish at the renormalization point. This criterion provides a scheme-independent estimation, but it violates the symmetry and transitivity properties of the RG and does not reproduce the Gell-Mann-Low scale for QED observables. The principle of maximum conformality (PMC) satisfies all of the deductions of the RG invariance-reflectivity, symmetry, and transitivity. Using the PMC, all nonconformal {βiR} terms (R stands for an arbitrary renormalization scheme) in the perturbative expansion series are summed into the running coupling, and one obtains a unique, scale-fixed, scheme-independent prediction at any finite order. The PMC scales and the resulting finite-order PMC predictions are both to high accuracy independent of the choice of initial renormalization scale, consistent with RG invariance. Moreover, after PMC scale setting, the residual initial scale dependence at fixed order owing to unknown higher-order {β i} terms can be substantially suppressed. The PMC thus eliminates a serious systematic scale error in perturbative quantum chromodynamics predictions, greatly improving the precision of tests of the Standard Model and the sensitivity to new physics at collider and other experiments. © 2012 American Physical Society.

Brodsky S.J.,SLAC | Wu X.-G.,SLAC | Wu X.-G.,Chongqing University
Physical Review D - Particles, Fields, Gravitation and Cosmology | Year: 2012

A major contribution to the uncertainty of finite-order perturbative QCD predictions is the perceived ambiguity in setting the renormalization scale μ r. For example, by using the conventional way of setting μ r∈[m t/2,2m t], one obtains the total tt̄ production cross section σ tt̄ with the uncertainty Δσ tt̄/σ tt̄∼ (+3%-4%) at the Tevatron and LHC even for the present next-to next-to-leading-order level. The principle of maximum conformality (PMC) eliminates the renormalization scale ambiguity in precision tests of Abelian QED and non-Abelian QCD theories. By using the PMC, all nonconformal {β i} terms in the perturbative expansion series are summed into the running coupling constant, and the resulting scale-fixed predictions are independent of the renormalization scheme. The correct scale displacement between the arguments of different renormalization schemes is automatically set, and the number of active flavors n f in the {β i} function is correctly determined. The PMC is consistent with the renormalization group property that a physical result is independent of the renormalization scheme and the choice of the initial renormalization scale μrinit. The PMC scale μrPMC is unambiguous at finite order. Any residual dependence on μrinit for a finite-order calculation will be highly suppressed since the unknown higher-order {β i} terms will be absorbed into the PMC scales' higher-order perturbative terms. We find that such renormalization group invariance can be satisfied to high accuracy for σ tt̄ at the next-to next-to-leading-order level. In this paper we apply PMC scale setting to predict the tt̄ cross section σ tt̄ at the Tevatron and LHC colliders. It is found that σ tt̄ remains almost unchanged by varying μrinit within the region of [m t/4,4m t]. The convergence of the expansion series is greatly improved. For the (qq̄) channel, which is dominant at the Tevatron, its next-to-leading-order (NLO) PMC scale is much smaller than the top-quark mass in the small x region, and thus its NLO cross section is increased by about a factor of 2. In the case of the (gg) channel, which is dominant at the LHC, its NLO PMC scale slightly increases with the subprocess collision energy √s, but it is still smaller than m t for √s≲1TeV, and the resulting NLO cross section is increased by ∼20%. As a result, a larger σ tt̄ is obtained in comparison to the conventional scale setting method, which agrees well with the present Tevatron and LHC data. More explicitly, by setting m t=172.9±1.1GeV, we predict σ Tevatron,1.96TeV=7.626-0.257+0.265pb, σ LHC,7TeV=171.8-5.6+5.8pb and σ LHC,14TeV=941.3-26. 5+28.4pb. © 2012 American Physical Society.

An axial flux permanent magnet energy harvester (AFPMEH) is proposed and analyzed for a vehicle magneto-rheological (MR) damper. The relationship between the output voltage and the input excitations are analytically developed. Under different constant rotation speeds and sinusoidal excitations, the harvesting energy is numerically computed for different loads of pure resistance and coil in the MR damper. To check the performance of the proposed AFPMEH for the MR damper, the AFPMEH and MR damper are fabricated individually. Experiments are performed to measure the harvesting energy of the AFPMEH and the damping characteristics of the MR damper under different excited conditions. The excited conditions include three constant rotation speeds and sinusoidal inputs. Load inputs of the pure resistance and the coil of the MR damper are considered. The results show that the time history of the generated voltage of the AFPMEH in experiment is agreed well with that of the AFPMEH in simulation. Under constant rotation speeds, the root mean square (rms) of loaded voltage will increase with the increment of load, whereas the rms of power will be affected by the amplitude of load. The MR damper powered by the AFPMEH can almost obtain the similar damping characteristics of that external power supply. Under sinusoidal inputs, the rms of loaded voltage will increase with the increment of external loads, whereas the rms of power will be almost kept as a constant. The damping range of the MR damper can also be enlarged over 30% comparing to off-state damping force. A quarter car model with an MR damper powered by the AFPMEH is developed to investigate the control performance. The on-off skyhook control is adopted to tune the input current of the MR damper. The vibration performance of the MR suspension is investigated under different roads and vehicle speeds. The numerical results show that the MR suspension with the AFPMEH under on-off skyhook control can achieve better ride comfort than the off case or the case without control. This indicates that the feasibility of AFPMEH in application of the vehicle MR suspension system. © 2016 IOP Publishing Ltd.

Liu R.,Chongqing University
Materials | Year: 2014

Inorganic/organic hybrid solar cells have attracted a lot of interest due to their potential in combining the advantages of both components. To understand the key issues in association with photoinduced charge separation/transportation processes and to improve overall power conversion efficiency, various combinations with nanostructures of hybrid systems have been investigated. Here, we briefly review the structures of hybrid nanocomposites studied so far, and attempt to associate the power conversion efficiency with these nanostructures. Subsequently, we are then able to summarize the factors for optimizing the performance of inorganic/organic hybrid solar cells. © 2014 by the authors.

Wang X.,Nanyang Technological University | Sun L.,Chongqing University | Zhang S.,Nanyang Technological University
ACS Applied Materials and Interfaces | Year: 2014

An optimized two-step anodization is developed to fabricate ultralong, small-diameter TiO2 nanotubes, that is, with tube length of up to 31 μm and pore diameter of about 35 nm in this work. This overcomes the length limitation of small diameter tubes that usually presents in conventional one-step anodization. The small tubes with lengths of 23 μm yield a conversion efficiency of 5.02% in dye-sensitized solar cells under nonoptimized conditions. © 2014 American Chemical Society.

Wu R.-C.,Anhui University | Hei X.-D.,Anhui University | Chen L.-P.,Chongqing University
Communications in Theoretical Physics | Year: 2013

Finite-time stability of a class of fractional-order neural networks is investigated in this paper. By Laplace transform, the generalized Gronwall inequality and estimates of Mittag-Leffler functions, sufficient conditions are presented to ensure the finite-time stability of such neural models with the Caputo fractional derivatives. Furthermore, results about asymptotical stability of fractional-order neural models are also obtained. © 2013 Chinese Physical Society and IOP Publishing Ltd.

Mojaza M.,University of Southern Denmark | Mojaza M.,SLAC | Brodsky S.J.,SLAC | Wu X.-G.,Chongqing University
Physical Review Letters | Year: 2013

We introduce a generalization of the conventional renormalization schemes used in dimensional regularization, which illuminates the renormalization scheme and scale ambiguities of perturbative QCD predictions, exposes the general pattern of nonconformal {βi} terms, and reveals a special degeneracy of the terms in the perturbative coefficients. It allows us to systematically determine the argument of the running coupling order by order in perturbative QCD in a form which can be readily automatized. The new method satisfies all of the principles of the renormalization group and eliminates an unnecessary source of systematic error. © 2013 American Physical Society.

Wang R.,Nanyang Technological University | Xu C.,Chongqing University | Lee J.-M.,Nanyang Technological University
Nano Energy | Year: 2016

NiOOH nanosheet/graphene hydrogels (H-NiOOH/GS), with mesoporous NiOOH nanosheets uniformly dispersed within the highly interconnected 3D graphene network, are constructed and studied for the first time by a mixed solvothermal and hydrothermal reaction. The effect of solvent composition on the morphology, phase, dispersibility of nanocrystal and hydrogel strength is systematically studied. As binder-free electrodes of supercapacitors, H-NiOOH/GS delivers high capacitance of 1162 Fg-1 at 1 Ag-1 with excellent rate capability (981 Fg-1 at 20 Ag-1). The charge-storage mechanisms of H-NiOOH/GS are in-depth investigated by quantifying the kinetics of charge storage, which reveals that NiOOH exhibits both capacitive effects and diffusion-controlled battery-type behavior during charge storage. Additionally, solvothermal-induced pure graphene hydrogels (H-GS) are also prepared and used as the negative electrode for the first time, which show an impressive specific capacitance of 425 and 368 Fg-1 at 5 and 40 mV s-1, respectively. Benefitting from the synergistic contribution of both positive and negative electrodes, the assembled H-NiOOH/GS//H-GS asymmetric supercapacitors achieve a remarkable energy density of 66.8 W h kg-1 at a power density of 800 W kg-1, and excellent cycling stability with 85.3% capacitance retention after 8000 cycles, holding great promise for energy storage applications. © 2015 Elsevier Ltd.

Zheng S.,Chongqing University
European Physical Journal C | Year: 2014

After the discovery of an SM-like Higgs with mh = 125 GeV, it is increasingly urgent to explore a solution to the hierarchy problem. In the context of MSSM from gauge-mediated SUSY breaking, the lower bound on the gluino mass suggests that the messenger scale M is probably large if the magnitude of Λ ~ 100 TeV. In this paper, we study the 5 + 5 model with M ~ 108-1012 GeV and Λ ~ 100 TeV. For moderate Higgs-messenger coupling, a viable model will be shown with moderate fine tuning. In this model, μ ~ 800 GeV, and Bμ nearly vanishes at the input scale, which can be constructed in a microscopic model. © 2014 The Author(s).

Yang T.,Stevens Institute of Technology | Chen G.,Chongqing University | Tian C.,Stevens Institute of Technology | Martini R.,Stevens Institute of Technology
Optics Letters | Year: 2013

The excitationwavelength for all-optical modulation of a 10.6 μmmid-infrared (MIR) quantumcascade laser (QCL)was varied in order to obtain maximum modulation depth. Both amplitude and wavelength modulation experiments were conducted at 820 nm and 1550 nm excitation respectively, whereby the latter matches the interband transition in the QCL active region. Experimental results show that for continuous-wave mode-operated QCL, the efficiency of free carrier generation is doubled under 1550 nm excitation compared with 820 nm excitation, resulting in an increase of the amplitude modulation index from 19% to 36%. At the same time, the maximum wavelength shift is more than doubled from 1.05 nm to 2.80 nm. Furthermore, for the first time to our knowledge, we demonstrated the optical switching of a QCL operated in pulse mode by simple variation of the excitation wavelength. © 2013 Optical Society of America.

Ding B.,Chongqing University
2010 8th IEEE International Conference on Control and Automation, ICCA 2010 | Year: 2010

This paper considers stabilization of discrete-time linear systems, where network exists for transmitting the sensor and controller information, and arbitrary bounded packet loss occurs between the sensor and controller, and between the controller and actuator. The stabilization of this system is transformed into the robust stabilization of a set of systems. A novel stability result is given for this system, which is specially applied on model predictive control (MPC) that explicitly considers the satisfaction of input and state constraints. A synthesis approach of MPC, parameterizing the infinite horizon control moves into a single state feedback law, is proposed. A simulation example is given to illustrate the effectiveness of the proposed MPC. © 2010 IEEE.

Wang H.,Chongqing University
Journal of Computational and Theoretical Nanoscience | Year: 2015

The intelligent material is a new marginal subject is developing in the world today, belongs to the frontier research field, it is the intersection of multi subjects. Characteristics and inherent in smart materials, therefore, it has important application value. This paper discusses the concept of intelligent materials, two kinds of new intelligent materials. The basic properties, smart material actuator and its application in intelligent control, compared with the traditional materials compared, smart materials exhibit superior quality. © 2015 American Scientific Publishers All rights reserved.

Xiao L.,Chongqing University | Cao Y.,Florida InternationalUniversity
Journal of Enhanced Heat Transfer | Year: 2012

The pulsating/oscillating heat pipe (PHP/OHP) is a relatively new, efficient, two-phase heat-Transfer device, which has attracted considerable interest due to its unique features in comparison with other types of heat pipes. In this paper, the most recent experimental and theoretical research work on the PHP and its derivatives is discussed and summarized. Many important features, parameters, significant conclusions, and comments of the subjects are presented in a tabular form. The effects of the main parameters on the thermal performance of the PHP and its derivatives are analyzed in depth. Although a complete theoretical understanding of the operational characteristics of the PHP is not yet achieved, there are many emerging niche applications of the PHP which are thoroughly reviewed. Finally, some directions and suggestions for PHP development in the future are given. © 2012 by Begell House, Inc.

Li D.,Chongqing University
Zhongguo Jiguang/Chinese Journal of Lasers | Year: 2010

Compression of speckle images is significant to storage reduction of measurement systems. We propose a coder for lossless compression of laser speckle images, which is based on speckle displacement estimation, temporal prediction and the Golomb coding. Firstly, speckle displacements are estimated for each subblock. Next, according to correlation properties of dynamic speckle, we set up the prediction model which predicted current pixels model. Finally, prediction errors are coded by the Golomb coding. Key features of the proposed speckle image coder include the estimation of speckle displacement by digital speckle image correlation method and the prediction modeling based on the extremum of the dynamic speckle correlation function. Experimental results show that the proposed coder provides good improvement in compression coding efficiency of laser speckle images.

The anterior cruciate ligament (ACL) is known to have a poor healing ability, especially in comparison with the medial collateral ligament (MCL) which can heal relatively well. Interleukin-1beta (IL-1β) is considered to be an important chemical mediator in the acute inflammatory phase of ligament injury. The role of IL-1β-induced expressions of lysyl oxidases (LOXs) and matrix metalloproteinases (MMPs), which respectively facilitate extracellular matrix (ECM) repair and degradation, is poorly understood. In this study, we aim to determine the intrinsic differences between ACL and MCL by characterising the differential expressions of LOXs and MMPs in response to IL-1β in the injury process. Semi-quantitative polymerase chain reaction (PCR), quantitative real-time PCR, Western blot, and zymography were performed. We detected high expressions of IL-1β-induced LOXs in normal ACL and MCL. Then, we found IL-1β induced injured MCL to express more LOXs than injured ACL (up to 2.85-fold in LOX, 2.58-fold in LOXL-1, 1.89-fold in LOXL-2, 2.46-fold in LOXL-3 and 2.18-fold in LOXL-4). Meanwhile, we found IL-1β induced injured ACL to express more MMPs than injured MCL (up to 1.72-fold in MMP-1, 1.95-fold in MMP-2, 2.05-fold in MMP-3 and 2.3-fold in MMP-12). The further protein results coincided with gene expressions above. Lower expressions of LOXs and higher expressions of MMPs might help to explain the poor healing ability of ACL.

Zhao Y.,Chongqing University
Zhongguo ying yong sheng li xue za zhi = Zhongguo yingyong shenglixue zazhi = Chinese journal of applied physiology | Year: 2010

To study isolation and culture from SD rat bone marrow mesenchymal stem cells (rBMMSCs) and differentiate into endothelial-like cells (ELCs) with VEGF and bFGF. In vitro rBMMSCs were cultured with the method of percoll (1.073 g/ml) density centrifugation and adherence to plastic dishes. Then they were seeded in LG-DMEM supplemented with 10% fetal bovine serum. The relative biologic characteristics of rBMMSCs including cell morphology, phenotype, growth curve, cell cycle and ultrastructure were studied by inverted microscope, immunocytochemistry, flow cytometry, MTT method, transmission electron microscopy(TEM). The induced cells were identified by immunocytochemistry with CD31, CD34, CD144(VE-cadherin), FITC-UEA-1 and had ability in Dil-ac-LDL uptake and were observed under inverted microscope. The morphology of rBMMSCs was spindle and has whirlpool. Growth curve of P4 showed that there was difference of latency, activity and flat periods. TEM showed that there were two of rMSCs , the small of both were infantile cells. GO/G1 phase of cell cycle was 95.67% and was suggested that most of cells were not in period of proliferation. The part differentiated cells demonstrated the characters of endothelial-like cells under inverted microscope and showed the expression of CD31, CD144, CD34, and possed the functions of endothelial-like cells staining double-positive for Dil-Ac-LDL and FTIC-UEA-1. 1.073 g/ml percoll density centrifugation and cultured adherence is an effective approach to obtain rBMMSCs. In vitro, the cells have potential to differentiate into endothelial-like cells

Zhao X.,Chongqing University
Experimental and Therapeutic Medicine | Year: 2013

Hawk tea (Litsea coreana Levl. var. lanuginose) is a traditional Chinese drink similar to green tea. In the present study, the preventive effects of Hawk tea on hepatic damage induced by carbon tetrachloride (CCl4) were studied in Sprague-Dawley rats. Silymarin was used as a positive control. Hawk tea was successfully shown to prevent hepatic damage in the rats. Serum levels of AST, ALT and LDH were significantly decreased when the rats were treated with varying concentrations of Hawk tea compared with silymarin (P<0.05). The lowest enzyme activities were exhibited in the 400 mg/kg Hawk tea group. This group showed reduced levels of the serum proinflammatory cytokines IL-6, IFN-γ and TNF-α. In particular, the IFN-γ level decreased markedly compared with the other concentration groups. The histopathology sections of liver tissue in the 400 mg/kg Hawk tea group recovered well from the CCl4 damage, but the sections of the other concentration groups showed necrosis to a more serious degree. Reverse transcription-polymerase chain reaction (RT-PCR) and western blot analyses of the inflammation-related genes iNOS, COX-2, TNF-α and IL-1β in the rat livers were tested. The 400 mg/kg Hawk tea group showed significantly decreased mRNA and protein expression levels of iNOS, COX-2, TNF-α and IL-1β compared with the control group. Accordingly, 400 mg/kg Hawk tea potentially contributes to the prevention of CCl4-induced hepatic damage in vivo. A 200 or 100 mg/kg dose of Hawk tea also demonstrated preventive effects against hepatic damage.

Huang J.L.,Chongqing University
Molekuliarnaia genetika, mikrobiologiia i virusologiia | Year: 2012

Mannanases can be useful in the food, feed, pulp and paper industries. In this research a Bacillus subtilis strain (named Bs5) which produced high-level beta-mannanase was isolated. Maximum level of beta-mannanase (1231.41 U/ml) was reached when Bacillus subtilis Bs5 was grown on konjac powder as the carbon source for nine hours at 32 degrees C. The beta-mannanase was a typical cold-active enzyme and its optimal temperature of 35 degrees C was the lowest among those of the known mannanases from bacteria. In addition, the optimal pH was 5.0 and much wide pH range from 3.0-8.0 was also observed in the beta-mannanase. These properties make the beta-mannanase more attractive for biotechnological applications. The DNA sequence coding the beta-mannanase was cloned and the open reading frame consisted of 1089 bp encoding 362 amino acids. A phylogenetic tree of the beta-mannanase based on the similarity of amino acid sequences revealed that the beta-mannanase formed a cluster with the beta-mannanases of Bacillus subtilis, which was separated from the mannanases of fungi and other bacteria. The beta-mannanase gene could be expressed in Escherichia coli and the recombinant beta-mannanase was characterized by Western blot. This study provided a new source of carbohydrate hydrolysis enzyme with novel characteristics from Bacillus subtilis.

Huang X.X.,Chongqing University
Journal of Global Optimization | Year: 2013

In this paper, we study a class of penalty methods for a class of constrained scalar set-valued optimization problems. We establish an equivalence relation between the lower semicontinuity at the origin of the optimal value function of the perturbed problem and the convergence of the penalty methods. Some sufficient conditions that guarantee the convergence of the penalty methods are also derived. © 2012 Springer Science+Business Media, LLC.

Huang J.,Nanyang Technological University | Wen C.,Nanyang Technological University | Wang W.,Tsinghua University | Song Y.-D.,Chongqing University
Automatica | Year: 2015

In this paper we consider finite-time leaderless consensus control of multi-agent systems consisting of a group of nonlinear mechanical systems with parametric uncertainties. New adaptive finite time continuous distributed control algorithms are proposed for the multi-agent systems. It is shown that the states of the mechanical systems can reach a consensus within finite time under an undirected graph. Transient performances in terms of convergence rates and time are also analyzed. Finally simulation results illustrate and verify the effectiveness of the proposed schemes. © 2014 Elsevier Ltd. All rights reserved.

Chern R.-L.,National Taiwan University | Han D.,Chongqing University
Optics Express | Year: 2014

Based on the effective medium model, nonlocal optical properties in periodic lattice of graphene layers with the period much less than the wavelength are investigated. Strong nonlocal effects are found in a broad frequency range for TM polarization, where the effective permittivity tensor exhibits the Lorentzian resonance. The resonance frequency varies with the wave vector and coincides well with the polaritonicmode. Nonlocal features are manifest on the emergence of additional wave and the occurrence of negative refraction. By examining the characters of the eigenmode, the nonlocal optical properties are attributed to the excitation of plasmons on the graphene surfaces. © 2014 Optical Society of America.

Wu X.-G.,Chongqing University
Journal of Physics: Conference Series | Year: 2014

Doubly heavy mesons and baryons provide a good platform for testing pQCD. Two high efficient generators BCVEGPY and GENXICC for simulating the hadronic production of the doubly heavy mesons and baryons have been developed in recent years. In this talk, we present their main idea and their recent progresses. The dominant gluon-gluon fusion mechanism programmed in those two generators are written based on the improved helicity amplitude approach, in which the hard scattering amplitude are dealt with directly at the amplitude level and the numerical efficiency are greatly improved by properly decomposing the Feynman diagrams and by fully applying the symmetries among them. Moreover, in comparison to the previous versions, we have updated the programs in order to generate the unweighted meson or baryon events much more effectively within various simulation environments. The generators can be conveniently imported into PYTHIA to do further hadronization and decay simulation, which have already been adopted by several collaborations as LHCb, CMS and etc. to do B c and Ξcc simulations. © Published under licence by IOP Publishing Ltd.

Huang T.,CAS Institute of High Energy Physics | Zhong T.,CAS Institute of High Energy Physics | Wu X.-G.,Chongqing University
Physical Review D - Particles, Fields, Gravitation and Cosmology | Year: 2013

Currently, not enough is known to determine the hadron distribution amplitudes (DAs) - which are universal physical quantities in the high-energy processes involving hadrons - in order to apply perturbative QCD to exclusive processes. Even for the simplest pion, one cannot discriminate between different DA models. Conversely, one expects that processes involving pions can in principle provide strong constraints on the pion DA. For example, the pion-photon transition form factor (TFF) can get accurate information about the pion wave function or DA due to the single pion in this process. However, the data from Belle and BABAR show a big difference regarding this TFF in high-Q2 regions; at present, they are unable to determine the pion DA. In the present paper, we think it is still possible to determine the pion DA as long as we perform a combined analysis of the existing data of the processes involving pions, such as π→μν̄, π0→γγ, B→πlν, D→πlν, etc. Based on the revised light-cone harmonic oscillator model, a convenient DA model is suggested, whose parameter B - which dominates its longitudinal behavior for φπ(x,μ2) - can be determined in a definite range by these processes. A light-cone sum rule analysis of the semileptonic processes B→πlν and D→πlν leads to a narrow region B=[0.01,0.14], which indicates a slight deviation from the asymptotic DA. Then, one can predict the behavior of the pion-photon TFF in high-Q2 regions which can be tested in future experiments. This method provides the possibility that the pion DA will be finally determined by a global fit. © 2013 American Physical Society.

Xin Y.,Chongqing University | Chu P.K.,City University of Hong Kong
Materials Chemistry and Physics | Year: 2010

In current paper, influence of tris-hydroxymethyl-aminomethane (tris) in simulated body fluid (SBF) on degradation behavior of pure magnesium is investigated using electrochemical tests as well as degradation measurement. Our results shows that tris mainly affects earlier degradation behavior of pure magnesium alloy. Tris and HCl used in preparation of SBF will form Tris-HCl which only lowers corrosion potential of magnesium slightly but accelerates degradation rates of pure magnesium by teens times. Consumption of OH - generated during magnesium dissolution by Tris-HCl progressively promotes transformation from Mg to Mg2+, which is the main reason for quite high degradation rate of pure magnesium in SBF. Pure magnesium is also more sensitive to pitting corrosion due to inclusion of Tris-HCl in SBF. This study deepens the understanding on degradation mechanism of biomedical magnesium alloys. © 2010 Elsevier B.V. All rights reserved.

Xiong W.,Chongqing University
Journal of Applied Physics | Year: 2012

Based on the framework of the effective-mass theory, the electronic structure of ZnO nanorods doped with manganese ions in the magnetic field is calculated by the Bessel function expanding method; the conduction and valence subbands are found to be non-degenerate in ZnO nanorods doped with manganese ions. The 10 lowest possible transitions are presented and the optical circularly polarized properties of each transition are also labeled. Through the analysis, the order of the valence subbands will change when the concentration of manganese ions varies, while the optical circularly polarized properties of the lowest transitions do not change when the magnetic field and the concentration of manganese ions increase. Meanwhile, each of the radiative intensities will increase with the increase of the wave vector. © 2012 American Institute of Physics.

Yang K.,Chongqing University
Magazine of Concrete Research | Year: 2016

The two-pressure-head sharp front (SF) model for unsaturated water transport was established to investigate the effects of drying temperature on the permeation properties of concrete. The proposed approach is capable of separating variations of obtained permeation properties caused by changes in moisture contents and/or microstructure. To verify this, two concretes with water/cement ratios of 0·65 and 0·35 were made. After curing, concrete samples were dried at four different temperatures ranging from 20°C to 105°C for 14 d. Sorptivity and water permeability were determined by the surface-mounted test through the SF model, as well as the standard water penetration method. The results show that an increase in drying temperature led to monotonic increases in sorptivity. Water permeability remained stable when the drying temperature was less than 40°C, but a significant increase was observed at temperatures beyond 60°C. The proposed method is a powerful tool that can be used to acquire variations in sorptivity and permeability before and after heat treatments, especially for the permeation properties of surface concrete.

Dong F.,Chongqing Technology and Business University | Zhao Z.,Chongqing Technology and Business University | Xiong T.,Chongqing Technology and Business University | Ni Z.,Chongqing Technology and Business University | And 3 more authors.
ACS Applied Materials and Interfaces | Year: 2013

The photocatalytic performance of the star photocatalyst g-C 3N4 was restricted by the low efficiency because of the fast charge recombination. The present work developed a facile in situ method to construct g-C3N4/g-C3N4 metal-free isotype heterojunction with molecular composite precursors with the aim to greatly promote the charge separation. Considering the fact that g-C 3N4 samples prepared from urea and thiourea separately have different band structure, the molecular composite precursors of urea and thiourea were treated simultaneously under the same thermal conditions, in situ creating a novel layered g-C3N4/g-C3N 4 metal-free heterojunction (g-g CN heterojunction). This synthesis method is facile, economic, and environmentally benign using easily available earth-abundant green precursors. The confirmation of isotype g-g CN heterojunction was based on XRD, HRTEM, valence band XPS, ns-level PL, photocurrent, and EIS measurement. Upon visible-light irradiation, the photogenerated electrons transfer from g-C3N4 (thiourea) to g-C3N4 (urea) driven by the conduction band offset of 0.10 eV, whereas the photogenerated holes transfer from g-C3N 4 (urea) to g-C3N4 (thiourea) driven by the valence band offset of 0.40 eV. The potential difference between the two g-C3N4 components in the heterojunction is the main driving force for efficient charge separation and transfer. For the removal of NO in air, the g-g CN heterojunction exhibited significantly enhanced visible light photocatalytic activity over g-C3N4 alone and physical mixture of g-C3N4 samples. The enhanced photocatalytic performance of g-g CN isotype heterojunction can be directly ascribed to efficient charge separation and transfer across the heterojunction interface as well as prolonged lifetime of charge carriers. This work demonstrated that rational design and construction of isotype heterojunction could open up a new avenue for the development of new efficient visible-light photocatalysts. © 2013 American Chemical Society.

Zhang P.,University of Connecticut | Li W.,BC Hydro | Li S.,University of Connecticut | Wang Y.,University of Connecticut | And 2 more authors.
Applied Energy | Year: 2013

Quantitative reliability assessment of photovoltaic (PV) power system is an indispensable technology to assure reliable and utility-friendly integration of PV generation. This paper reviews the state-of-the-art technologies for evaluating the reliability of large-scale PV systems and the effect of PV interconnection on the reliability of local distribution system. The discussions are extended to emerging research topics including time varying and ambient-condition-dependent failure rates of critical PV system components, accurate operating models of PV generators in both interconnected and islanded modes, and the reliability evaluation of active distribution networks with PV penetration and transmission level Giga-PV system. A vision for the future research is presented, with a focus on the cyber-physical perspective of the PV reliability, modeling of PV voltage control scheme for reliability assessment, reliability assessment for PV systems under extreme events and PV reliability assessment considering cybersecurity. © 2012 Elsevier Ltd.

Xu X.,Chongqing University
International journal of environmental research and public health | Year: 2011

In this study, Fe(3)O(4)/SiO(2)/TiO(2) photocatalyst was prepared via a sol-gel method, and Fe(3)O(4) particles were used as the core of the colloid. Diffraction peaks of Fe(3)O(4) crystals are not found by XRD characterization, indicating that Fe(3)O(4) particles are well encapsulated by SiO(2). FTIR characterization shows that diffraction peaks of Ti-O-Si chemical bonds become obvious when the Fe(3)O(4) loading is more than 0.5%. SEM characterization indicates that agglomeration occurs in the Fe(3)O(4)/SiO(2)/TiO(2) photocatalyst, whereas photocatalysts modified by Fe(3)O(4)/SiO(2) present excellent visible light absorption performance and photocatalytic activity, especially when the Fe(3)O(4) loading is 0.5%. Photocatalytic degradation of glyphosate in soil by these photocatalysts under solar irradiation was investigated. Results show that 0.5% Fe(3)O(4)/SiO(2)/TiO(2) has the best photocatalytic activity. The best moisture content of soil is 30%~50%. Degradation efficiency of glyphosate reaches 89% in 2 h when the dosage of photocatalyst is 0.4 g/100 g (soil), and it increased slowly when more photocatalyst was used. Soil thickness is a very important factor for the photocatalytic rate. The thinner the soil is, the better the glyphosate degradation is. Degradation of glyphosate is not obviously affected by sunlight intensity when the intensity is below 6 mW/cm(2) or above 10 mW/cm(2), but it is accelerated significantly when the sunlight intensity increases from 6 mW/cm(2) to 10 mW/cm(2).

Zhang X.,City University of Hong Kong | Wu Y.,Zhejiang University | Shen L.,Chongqing University | Skitmore M.,Queensland University of Technology
International Journal of Project Management | Year: 2014

There is a worldwide demand for an increasingly sustainable built environment. This has resulted in the need for a more accurate evaluation of the level of sustainability of construction projects. To do this it involves the development of better measurement and benchmarking methods. One approach is to use a theoretical model to assess construction projects in terms of their sustainable development value (SDV) and sustainable development ability (SDA) for implementation in the project life cycle, where SDA measures the contribution of a project to development sustainability and as a major criterion for assessing its feasibility.This paper develops an improved SDA prototype model that incorporates the effects of dynamical factors on project sustainability. This involves the introduction of two major factors concerning technological advancement and changes in people's perceptions. A case study is used to demonstrate the procedures involved in simulation and modeling, one outcome of which is to demonstrate the greater influence of technological advancement on project sustainability than changes in perception. © 2013 Elsevier Ltd and IPMA.

Ding Y.,General Education College | Liao Z.,Chongqing University
Physica B: Condensed Matter | Year: 2015

Abstract Fano resonance exhibits high sensitivity and promising applications in the field of ultra-sensitive plasmonic sensor. In this work, the Fano lineshape in spectra of gold rectangular split nanorings (RSNRs) is investigated using the finite element method. The simulation results figure out the Fano lineshape could be modulated by the positions of split gap in RSNRs for symmetry breaking, which is explained by the plasmonic hybridization theory. Furthermore, the high order bonding plasmon mode H in absorption spectra exhibits high sensitivity in visible region. Our investigations here are beneficial for the design and application of ultra-sensitive LSPR sensor in visible region. © 2014 Elsevier B.V. All Rights reserved.

Huang B.,Tsinghua University | Li C.,Tsinghua University | Yin C.,Chongqing University | Zhao X.,NDTech Co.
International Journal of Advanced Manufacturing Technology | Year: 2013

In order to address the key problems faced by small- and medium-sized enterprises (SMEs), existing solutions and shortcomings were analyzed. The possibilities by using the new emerged technologies and theories (e.g., cloud computing, internet of things, service-oriented technology) to solve the bottlenecks faced by SMEs are investigated. The idea of manufacturing resource and capability sharing based on cloud computing for SME is discussed, and an SME-oriented cloud manufacturing service platform (SME-CMfgSP) is introduced. The architecture of SME-CMfgSP is proposed, and the key technologies for implementing SME-CMfgSP are introduced in details. The challenges for implementing cloud manufacturing service platform for SMEs were discussed. A case study is described to illustrate the application of the proposed SME-CMfgSP. © 2012 Springer-Verlag London Limited.

Sima W.-X.,Chongqing University
Journal of Electrical Engineering and Technology | Year: 2015

The effect of altitude on thermal conduction, surface temperature, and thermal radiation of partial arc was investigated on the basis of molecular gas dynamics to facilitate a deep understanding of the pollution surface discharge mechanism. The DC flashover model was consequently modified at high altitude. The validity of the modified DC flashover model proposed in this paper was proven through a comparison with the results of high-altitude simulation experiments and earlier models. Moreover, the modified model was found to be better than the earlier modified models in terms of forecasting the flashover voltage. Findings indicated that both the thermal conduction coefficient and the surface thermodynamics temperature of partial arc had a linear decrease tendency with the altitude increasing from 0 m to 3000 m, both of which dropped by approximately 30% and 3.6%, respectively. Meanwhile, the heat conduction and the heat radiation of partial arc both had a similar linear decrease of approximately 15%. The maximum error of DC pollution flashover voltage between the calculation value according to the modified model and the experimental value was within 6.6%, and the pollution flashover voltage exhibited a parabola downtrend with increasing of pollution. © The Korean Institute of Electrical Engineers.

Li B.L.,Southwest University | Luo H.Q.,Southwest University | Lei J.L.,Chongqing University | Li N.B.,Southwest University
RSC Advances | Year: 2014

Hemin-functionalized MoS2 nanosheets (hemin/MoS2-NSs) are first obtained via van der Waals interactions between few-layered MoS 2 nanosheets (MoS2-NSs) and hemin molecules. It is demonstrated that a portion of MoS2-NSs undergoes a phase transition from semiconducting to metallic phase under the influence of hemin, which shows the coexistence of semiconducting and metallic phases in the crystal structure of hemin/MoS2-NSs. MoS2-NSs prepared from sonication-induced exfoliation of bulk MoS2 crystals in aqueous surfactant solution exhibit intrinsic peroxidase-like activity for the oxidation of 3,3,5,5-tetramethylbenzidine in the presence of H2O2, which is further improved by the functionalization of hemin. Significantly, MoS2-NSs are presented as a new support of hemin, and when compared to MoS2-NSs, hemin/MoS2-NSs exhibit better dispersity in aqueous solution, which is used in the development of H2O2 sensor based on the enhanced peroxidase-like activity. © The Royal Society of Chemistry 2014.

Lu Y.,University of Ottawa | Zhu T.,University of Ottawa | Zhu T.,Chongqing University | Chen L.,University of Ottawa | Bao X.,University of Ottawa
Journal of Lightwave Technology | Year: 2010

We developed a distributed vibration sensor by using heterodyne detection and signal processing of moving averaging and moving differential for the phase optical time domain reflectometry system. The broadband acoustic frequency components generated by pencil-break vibration have been measured and identified in location by our distributed vibration sensor for the first time. Pencil break measurement is a standard technique to emulate the acoustic emission of cracks in concrete or steel bridges for early crack identification. The spatial resolution is 5m and the highest frequency response is 1 kHz, which is limited by the trigger frequency of data acquisition card. This new sensing system can be used for vibration detection of health monitoring of various civil structures as well as any dynamic monitoring requirement. © 2006 IEEE.

Yang J.,Georgia Institute of Technology | Yang J.,Chongqing University | Chen J.,Georgia Institute of Technology | Yang Y.,Georgia Institute of Technology | And 6 more authors.
Advanced Energy Materials | Year: 2014

Vibrations in living environments are generally distributed over a wide frequency spectrum and exhibit multiple motion directions over time, which renders most of the current vibration energy harvesters unpractical for their harvesting purposes. Here, a 3D triboelectric nanogenerator (3D-TENG) is designed based on the coupling of the triboelectrification effect and the electrostatic induction effect. The 3D-TENG operates in a hybridization mode of conjuntioning the vertical contact-separation mode and the in-plane sliding mode. The innovative design facilitates harvesting random vibrational energy in multiple directions over a wide bandwidth. An analytical model is established to investigate the mechano-triboelectric transduction of 3D-TENG and the results agree well with experimental data. The 3D-TENG is able to harvest ambient vibrations with an extremely wide working bandwidth. Maximum power densities of 1.35 W m-2 and 1.45 W m-2 are achieved under out-of-plane and in-plane excitation, respectively. The 3D TENG is designed for harvesting ambient vibration energy, especially at low frequencies, under a range of conditions in daily life and has potential applications in environmental/ infrastructure monitoring and charging portable electronics. A 3D triboelectric nanogenerator (TENG) is designed to harvest random vibrational energy in an ambient environment. The device is able to scavenge vibrational energy in the out-of-plane direction, with an extremely wide working bandwidth of 75 Hz, and arbitrary in-plane directions with a bandwidth of 14.4 Hz. This expands the applications of TENG in environmental/infrastructure monitoring and charging portable electronics. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Liu H.,Chongqing University
Current stem cell research & therapy | Year: 2012

The alternative splicing of precursor mRNA is an essential mechanism for protein diversity. It plays important biological roles, such as proliferation, differentiation and development of cells. Furthermore, alternative splicing participates in the pathogenesis of diseases, including cancer. Thus, in-depth understanding of splicing regulation is of great significance. Regulation of alternative splicing is an extraordinary complicated process in which several signal molecules are at work. Besides the cis-elements and trans-factors, several lines of evidences suggest that other molecules, structures or process also regulate splicing, such as RNA structures, transcription and transcription factors, chromatin and protein. Meanwhile, increasing body of evidence shows that alternative splicing correlated closely to stem cell lineage differentiation. It means that there is a fundamental role for splicing in controlling regulatory program required for cell lineage differentiation. This review systematically sums up the regulation of alternative splicing and summarizes the splicing events during cell lineage differentiation of stem cells.

Gao T.,Shanghai JiaoTong University | Lin W.,Shanghai JiaoTong University | Gu A.,Shanghai JiaoTong University | Gu M.,Chongqing University
Applied Energy | Year: 2010

Coalbed methane (CBM) is an important global energy resource and liquefaction is suggested to best utilize it. Different from ordinary natural gas, CBM usually contains a high proportion of nitrogen, which cannot be removed by purification procedures applied in ordinary natural gas liquefaction processes. One approach for separating nitrogen from CBM is by distillation after liquefaction. In this way, nitrogen is liquefied together with methane, and the liquefaction system performance may change along with the nitrogen content of CBM feed gas. The liquefaction process adopting nitrogen expansion with propane pre-cooling is usually considered suitable for small-scale liquefaction plants due to its simplicity and is the focus of this paper. Taking the unit product liquefaction power consumption as the major index for analysis, optimum parameters of the liquefaction process for CBM feed gas containing different nitrogen contents are calculated. Based on the optimization results, the effects of nitrogen content as well as the other two important technical indexes (liquefaction rate and methane recovery rate) on system performance are also investigated. © 2009 Elsevier Ltd. All rights reserved.

Tang J.,Chongqing University | Li W.,Virginia Polytechnic Institute and State University | Liu Y.,Virginia Polytechnic Institute and State University
IEEE Transactions on Power Delivery | Year: 2010

Partial discharge (PD) source signals concurring at different internal positions in gas insulated switchgear (GIS) may be mixed linearly or nonlinearly when they are propagating through GIS pipes. To identify the interior insulation defects in GIS, it is important and intricate to extract these individual PD source signals from the mixed PD signals. This paper applies the blind source separation (BSS) theory to acquire individual source signals assisted by complex wavelet transform. First, a maximizing signal-to-noise ratio (MSNR) BSS algorithm is introduced. Then simulated PD mixed signals are constructed from four individual ultra-high frequency theoretical PD signals and employed to implement BSS separation. Finally, two typical individual PD signals sampled from GIS model are adopted for testing. Both can produce satisfying result, which shows that it is feasible to apply BSS to separate the mixed PD signals in GIS. © 2009 IEEE.

Xie K.,Chongqing University | Billinton R.,University of Saskatchewan
IEEE Transactions on Energy Conversion | Year: 2011

The economic and reliability benefits of adding a wind energy conversion system (WECS) to a power system are highly dependent on the wind turbine generator (WTG) installation design, i.e., the type and number of WTG. This paper presents an approach to determine the optimum installation design at each wind site considering the WTG parameters, the total cost of WECS and the power system reliability performance. The model is formulated as a combinatorial constrained optimization problem with a nonlinear, nondifferentiable objective function, which consists of the capital, maintenance and operating costs, and the costumer interruption costs. A number of constraints, including the total installed capacity at a specific wind site and the capital cost, are considered in the model. The model is solved using a genetic algorithm with adaptive crossover and mutation probabilities based on the standard deviation of chromosome fitness in a generation population. The proposed model and algorithm are tested on two power systems. The results show that the proposed approach can be used to obtain the maximum economic and reliability benefits associated with a WECS installation and is a powerful search technique for determining the optimum number and type of WTG considering reliability performance and costs. © 2010 IEEE.

Wang Z.,Chongqing University | Zhang S.,University of Sichuan
Archive for Rational Mechanics and Analysis | Year: 2015

In this paper, we prove the existence of a family of new non-collision periodic solutions for the classical Newtonian n-body problems. In our assumption, the (Formula presented.) particles are invariant under the dihedral rotation group Dl in (Formula presented.) such that, at each instant, the n particles form two twisted l-regular polygons. Our approach is the variational minimizing method and we show that the minimizers are collision-free by level estimates and local deformations. © 2015 Springer-Verlag Berlin Heidelberg

Zhang G.,China Agricultural University | Liang Y.,Chongqing University
Archives of Microbiology | Year: 2013

Cordyceps militaris is a heterothallic ascomycetous fungus that has been cultivated as a medicinal mushroom. This study was conducted to improve fruiting body production by PCR assessment. Based on single-ascospore isolates selected from wild and cultivated populations, the conserved sequences of α-BOX in MAT1-1 and HMG-BOX in MAT1-2 were used as markers for the detection of mating types by PCR. PCR results indicated that the ratio of mating types is consistent with a theoretical ratio of 1:1 (MAT1-1:MAT1-2) in wild (66:70) and cultivated (71:60) populations. Cross-mating between the opposite mating types produced over fivefold more well-developed fruiting bodies than self- or cross-mating between strains within the same mating type. This study may serve as a valuable reference for artificial culturing of C. militaris and other edible and medicinal mushrooms and may be useful to develop an efficient process for the selection, domestication, and management of strains for industrial-scale production. © 2013 Springer-Verlag Berlin Heidelberg.

Zhao X.,Pusan National University | Zhao X.,Chongqing University | Kim S.-Y.,National Academy of Agricultural Science NAAS | Park K.-Y.,Pusan National University
Journal of Medicinal Food | Year: 2013

Bamboo salt is a traditional food widely used in Korea. The in vitro anticancer effects of this salt were evaluated in HCT-116 human colon cancer cells using a 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyltetrazolium bromide (MTT) assay. A 1% salt concentration of bamboo salt baked nine times (9×) inhibited the growth of HCT-116 cells by 53%, which was higher than salt baked three times (3×) or once (1×; 44% and 41%, respectively) and much higher than solar sea salt (Korean sea salt) and purified salt (22% and 18%, respectively). To elucidate the inhibitory mechanisms underlying the anticancer effect of the salt samples in cancer cells, expression of genes associated with apoptosis, inflammation, and metastasis was measured with reverse transcription-polymerase chain reaction and Western blotting. Bamboo salt (9×) significantly induced apoptosis in cancer cells (P<.05) by upregulating Bax, caspase-9, and caspase-3, and downregulating Bcl-2. The expression of genes associated with inflammation (NF-κB, iNOS, and COX-2) was significantly downregulated (P<.05) by 9× bamboo salt, demonstrating its anti-inflammatory properties. The 9× bamboo salt also exerted a greater anti-metastatic effect on cancer cells than the other salts as demonstrated by decreased mRNA expression of MMP genes and increased expression of tissue inhibitors of metalloproteinases, which was confirmed by the inhibition of tumor metastasis induced in colon 26-M3.1 cells in BALB/c mice. In contrast, purified and solar salts increased metastasis in the mice. Our results demonstrated that 9× bamboo salt had the most potent in vitro anticancer effect, induced apoptosis, had anti-inflammatory activities, and exerted in vivo anti-metastatic effects. Additionally, the anticancer, anti-inflammatory, and anti-metastatic effects of the 1× and 3× bamboo salts were stronger than those of the purified and solar salts. © Copyright 2013, Mary Ann Liebert, Inc. and Korean Society of Food Science and Nutrition.

Jiang H.,Chongqing University
Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science | Year: 2015

Time-varying sliding friction force and friction torque are regarded as non-negligible excitation sources of vibration and noise in gears. The sliding friction force primarily excites the motion along the off-line-of-action direction, which transmits vibration to the housing through shafts and bearings and then radiates noise. Since the contact line intersects with the pitch line, and the directions of the friction forces are opposite on both sides of the pitch line, the calculation of the friction excitations in helical gears becomes more difficult, especially in the high contact ratio helical gears. However, there is no universal method for calculating the friction excitations in helical gears with different range of contact ratio. The changes of friction excitations in helical gears are highly dependent on the geometric parameters such as helix angle and face width among others. Yet, there exist very limited studies on these topics. In this study, a refined general formulation for the calculation of time-varying contact line and friction excitations is proposed by assuming uniform load distribution along the contact lines with time-varying normal force and friction coefficient. Key gear parameters such as modification coefficient, helix angle, and face width are analyzed to illustrate their effects on the time-varying contact line and friction excitations. The results demonstrate that the refined general formulation is effective for the calculation of the friction excitations in helical gears with different range of contact ratio, and the parametric analysis could supply some guidance for choosing gear parameters in the design of helical gears to reduce the friction excitations. © 2015 IMechE.

Luo X.,Chongqing University | Xia Y.,Chongqing Key Laboratory of Software Theory and Technology | Zhu Q.,Chongqing Key Laboratory of Software Theory and Technology
Knowledge-Based Systems | Year: 2013

Matrix Factorization (MF) based Collaborative Filtering (CF) have proved to be a highly accurate and scalable approach to recommender systems. In MF based CF, the learning rate is a key factor affecting the recommendation accuracy and convergence rate; however, this essential parameter is difficult to decide, since the recommender has to keep the balance between the recommendation accuracy and convergence rate. In this work, we choose the Regularized Matrix Factorization (RMF) based CF as the base model to discuss the effect of the learning rate in MF based CF, trying to deal with the dilemma of learning rate tuning through learning rate adaptation. First of all, we empirically validate the affection caused by the change of the learning rate on the recommendation performance. Subsequently, we integrate three sophisticated learning rate adapting strategies into RMF, including the Deterministic Step Size Adaption (DSSA), the Incremental Delta Bar Delta (IDBD), and the Stochastic Meta Decent (SMD). Thereafter, by analyzing the characteristics of the parameter update in RMF, we further propose the Gradient Cosine Adaption (GCA). The experimental results on five public large datasets demonstrate that by employing GCA, RMF could maintain good balance between accuracy and convergence rate, especially with small learning rate values. © 2012 Elsevier B.V. All rights reserved.

Zhu Y.,Chongqing University
Electronic Journal of Geotechnical Engineering | Year: 2016

Deep foundation pit supporting technology is built on geological, environmental, hydrological, and other factors, and it is applied into geotechnical engineering construction. There are various problems that arise in the process of deep foundation pit supporting construction. Geotechnical engineering should take the integrated use of several kinds of technologies into consideration, such as sloping excavation, cement walls, piles in row, bolting supporting, soil nailing wall supporting and perforated pipe grouting and others. Through the application of a tunnel geotechnical engineering construction technology of deep foundation pit supporting, from the point of views of engineering overview, hydrogeological conditions, scheme selection of foundation pit supporting, excavation safety monitoring, comprehensively considering the economic, security and reliability factors, selecting the most reasonable and scientific supporting program to ensure the construction quality and efficiency of deep foundation pit supporting reach the expected engineering construction benefit.

Ding B.,Chongqing University | Huang B.,University of Alberta | Xu F.,University of Alberta
International Journal of Systems Science | Year: 2011

The synthesis approach for dynamic output feedback robust model predictive control is considered. The notion of quadratic boundedness is utilised to characterise the stability properties of the augmented closed-loop system. A finite horizon performance cost, which corresponds to the worst case of both the polytopic uncertainty and the bounded disturbance/noise, is utilised. It is not required to specify the horizon length. A numerical example is given to illustrate the effectiveness of the proposed controller. © 2011 Taylor & Francis.

Li Q.,Chongqing University | Yang X.-S.,Huazhong University of Science and Technology
International Journal of Bifurcation and Chaos | Year: 2010

This paper presents an efficient method for finding horseshoes in dynamical systems by using several simple results on topological horseshoes. In this method, a series of points from an attractor of a map (or a Poincaré map) are firstly computed. By dealing with the series, we can not only find the approximate location of each short unstable periodic orbit (UPO), but also learn the dynamics of almost every small neighborhood of the attractor under the map or the reverse map, which is very helpful for finding a horseshoe. The method is illustrated with the Hénon map and two other examples. Since it can be implemented with a computer software, it becomes easy to study the existence of chaos and topological entropy by virtue of topological horseshoe. © 2010 World Scientific Publishing Company.

Zhao J.,University of Akron | Wang Q.,University of Akron | Liang G.,Chongqing University | Zheng J.,University of Akron
Langmuir | Year: 2011

Accumulation of small soluble oligomers of amyloid-β (Aβ) in the human brain is thought to play an important pathological role in Alzheimer's disease. The interaction of these Aβ oligomers with cell membrane and other artificial surfaces is important for the understanding of Aβ aggregation and toxicity mechanisms. Here, we present a series of exploratory molecular dynamics (MD) simulations to study the early adsorption and conformational change of Aβ oligomers from dimer to hexamer on three different self-assembled monolayers (SAMs) terminated with CH 3, OH, and COOH groups. Within the time scale of MD simulations, the conformation, orientation, and adsorption of Aβ oligomers on the SAMs is determined by complex interplay among the size of Aβ oligomers, the surface chemistry of the SAMs, and the structure and dynamics of interfacial waters. Energetic analysis of Aβ adsorption on the SAMs reveals that Aβ adsorption on the SAMs is a net outcome of different competitions between dominant hydrophobic Aβ-CH 3-SAM interactions and weak CH 3-SAM-water interactions, between dominant electrostatic Aβ-COOH-SAM interactions and strong COOH-SAM-water interactions, and between comparable hydrophobic and electrostatic Aβ-OH-SAM interactions and strong OH-SAM-water interactions. Atomic force microscopy images also confirm that all of three SAMs can induce the adsorption and polymerization of Aβ oligomers. Structural analysis of Aβ oligomers on the SAMs shows a dramatic increase in structural stability and β-sheet content from dimer to trimer, suggesting that Aβ trimer could act as seeds for Aβ polymerization on the SAMs. This work provides atomic-level understanding of Aβ peptides at interface. © 2011 American Chemical Society.

Ding B.,Chongqing University
Fuzzy Sets and Systems | Year: 2010

This paper improves some results in [Antonio Sala, Carlos Ariño, Asymptotically necessary and sufficient conditions for stability and performance in fuzzy control: applications of Polya's theorem, Fuzzy Sets and Systems 158 (2007) 2671-2686]. In the relaxation of the stability results, only a smaller number of artificial decision variables are required. Thus, we obtain the equivalent stability results, with lower requirement on the computation. © 2010 Elsevier B.V. All rights reserved.

Chen G.,Chongqing University
International Journal of Robust and Nonlinear Control | Year: 2015

This paper addresses the synchronization problems with/without a dynamic leader for a team of distributed Lagrange systems on digraph. A systematic way to design and analyze the distributed control algorithms is presented. The contributions of the paper are twofold. First, the adaptive coordination control protocols are proposed for synchronization of networked uncertain Lagrange systems with/without tracking. This protocol can guarantee synchronization in finite time. Second, the design of the distributed tracking controller for the networked dynamic systems is proposed by using Lyapunov methods. The development is suitable for the general digraph communication topologies. Simulation examples are included to demonstrate the effectiveness of the proposed algorithms. Copyright © 2014 John Wiley & Sons, Ltd.

Su X.,Key Laboratory of Dependable Service Computing | Su X.,Chongqing University | Wu L.,Harbin Institute of Technology | Shi P.,Harbin Engineering University | And 3 more authors.
IEEE Transactions on Fuzzy Systems | Year: 2015

In this paper, the model approximation problem is investigated for a Takagi-Sugeno fuzzy switched system with stochastic disturbance. For a high-order considered system, our attention is focused on the construction of a reduced-order model, which not only approximates the original system well with a Hankel-norm performance but translates it into a lower dimensional fuzzy switched system as well. By using the average dwell time approach and the piecewise Lyapunov function technique, a sufficient condition is first proposed to guarantee the mean-square exponential stability with a Hankel-norm error performance for the error system. The model approximation is then converted into a convex optimization problem by using a linearization procedure. Finally, simulations are provided to illustrate the effectiveness of the proposed theory. © 2014 IEEE.

He Z.,Lanzhou University | Zhou X.,Lanzhou University | Zhou X.,Chongqing University
Thin-Walled Structures | Year: 2014

Distortional buckling mode of cold-formed steel thin-walled member is an unstable behavior, and in some cases it may govern the load-carrying capacity of the member. The source, evolution and performance of the formulas and test data for the two strength design curves developed by Hancock are studied, for predicting the load-carrying capacity in the distortional mode. A proposed strength design curve based on available test data and Hancock× ©2014 Elsevier Ltd. All rights reserved.

Liangcai Z.,Chongqing University | Wujie S.,Chongqing University of Arts and Sciences
Acta Mathematica Scientia | Year: 2011

Let G be a finite group and π(G)={p1, p2,...,pk{ be the set of the primes dividing the order of G. We define its prime graph γ(G) as follows. The vertex set of this graph is π(G), and two distinct vertices p, q are joined by an edge if and only if pq e{open}πe(G). In this case, we write p~q. For pe{open}π(G), put deg(p):=∥{qe{open} π(G) ∥ p~ q∥, which is called the degree of p. We also define D(G):=(deg(p1), deg(p2),..., deg(pk)), where p1 < p2 <...< pk, which is called the degree pattern of G. We say a group G is k-fold OD-characterizable if there exist exactly k non-isomorphic finite groups with the same order and degree pattern as G. Specially, a 1-fold OD-characterizable group is simply called an OD-characterizable group. Let L:=U6(2). In this article, we classify all finite groups with the same order and degree pattern as an almost simple groups related to L. In fact, we prove that L and L.2 are OD-characterizable, L.3 is 3-fold OD-characterizable, and L.S3 is 5-fold OD-characterizable. © 2011 Wuhan Institute of Physics and Mathematics.

Chen L.,Hefei University of Technology | He Y.,Hefei University of Technology | Chai Y.,Chongqing University | Wu R.,Anhui University
Nonlinear Dynamics | Year: 2014

The asymptotic stability and stabilization problem of a class of fractional-order nonlinear systems with Caputo derivative are discussed in this paper. By using of Mittag-Leffler function, Laplace transform, and the generalized Gronwall inequality, a new sufficient condition ensuring local asymptotic stability and stabilization of a class of fractional-order nonlinear systems with fractional-order α:1<α<2 is proposed. Then a sufficient condition for the global asymptotic stability and stabilization of such system is presented firstly. Finally, two numerical examples are provided to show the validity and feasibility of the proposed method. © 2013 Springer Science+Business Media Dordrecht.

Lai P.,Chongqing University
Yi chuan = Hereditas / Zhongguo yi chuan xue hui bian ji | Year: 2012

The seasonal reproduction of mammal means the reproduction experiences an annual period from quiescence to renaissance. Studies have shown that kisspeptin and RFRP play an important role in the reproductive seasonality. The non-breeding season is characterized by an increase in the negative feedback effect of estrogen on GnRH, and this effect is transmitted by kisspeptin neurons, which may be an important factor affecting the reproduction activities. The expression of RFRP depends on melatonin secretion, and shows an apparent inhibition on reproduction in non-breeding season. In addition, thyroid hormones influence termination of the breeding season. Dopaminergic neuron A14/A15 also contributes to the seasonal changes in estrogen negative feedback. These neural systems may synergistically modulate the seasonal changes of reproductive function with the photoperiod. This review makes a systematic expatiation on the relationship between seasonal reproduction and these neural systems.

Tu W.,University of Toronto | Tu W.,Chongqing University | Chin Y.-H.,University of Toronto
Journal of Catalysis | Year: 2014

Rate measurements, carried out after elimination of transport corruptions, show that CH3OH partial oxidation on Pt clusters proceeds via three distinctly different kinetic regimes defined by the operating oxidant-to-reductant (O2-to-CH3OH) ratio. These kinetic regimes, each with unique rate dependencies for HCHO, HCOOCH3, and CO2 formation, arise from a dynamic shift in the identity and coverages of reactive intermediates on Pt cluster surfaces from saturated with chemisorbed oxygen, to uncovered, and then to partially covered with methanol derived species as the oxygen chemical potential at cluster surfaces decreases with decreasing O2-to-CH3OH ratio. HCHO formation rates first remain insensitive to O2 on Pt cluster surfaces saturated with chemisorbed oxygen (O*), then increase proportionally with O2 as cluster surfaces depleted of oxygen and as unoccupied Pt sites become the most abundant surface intermediates, and eventually increase more than linearly with O2 on Pt surfaces predominantly covered with CH3OH derived intermediates. The transition in rate dependence on O2 is accompanied by a concomitant transition on CH3OH dependence: HCHO formation rates are linearly proportional to, then independent of, and eventually inhibited by CH3OH as the O2-to-CH 3OH ratio decreases. Similar transition in reaction orders is also found for HCOOCH3 and CO2 formation. The first-order rate coefficient for CH3OH oxidation is a single-valued function of the operating O2-to-CH3OH ratio, because the ratio determines the oxygen chemical potential at Pt cluster surfaces via the kinetic coupling of O2 and CH3OH activation steps and, in turn, the identity and coverage of reactive intermediates, the nature and availability of active sites, and the identity of kinetically-relevant steps. © 2014 Elsevier Inc. All rights reserved.

Jia G.,City University of Hong Kong | Tanner P.A.,City University of Hong Kong | Duan C.-K.,Chongqing University | Dexpert-Ghys J.,CNRS Toulouse Center for Materials Elaboration and Structural Studies
Journal of Physical Chemistry C | Year: 2010

Yttrium orthorborate YBO3 containing 0.5 or 5 atom % of Eu 3+ has been prepared by the spray-pyrolysis method. Low-temperature, high-resolution emission spectroscopy has been used to probe the local site symmetries of Eu3+ ions accommodated on the Y3+ sites in YBO 3:Eu3+ (0.5 atom %) and hence to determine the crystal structure of the title compound. The use of point group selection rules enabled a consistent spectral interpretation by envisaging distinct Ci and C1 symmetry Eu3+ sites, in accordance with the neutron diffraction study of Lin et al. (Chem. Mater. 2004, 16, 2418). The assignment of features in the 10 K visible absorption spectrum of YBO3:Eu 3+ (5 atom %) is also consistent with the two-site model, but it was found that the site occupation by Eu3+ differs from the expected ratio 2C1:1Ci. The fitting of 31 crystal-field levels of the C1 site has been made with some approximations by employing 7 parameters. In addition, the emission spectrum of YBO3:Eu 3+ containing a trace amount of Y3BO6 has been compared with those of YBO3:Eu3+ and Y3BO 6: Eu3+, which serves as a reference to elucidate the concern on the red/orange color ratio of YBO3:Eu3+ emission. © 2010 American Chemical Society.

Batchelor M.T.,Chongqing University | Batchelor M.T.,Australian National University
International Journal of Modern Physics B | Year: 2014

The scattering matrix (S-matrix), relating the initial and final states of a physical system undergoing a scattering process, is a fundamental object in quantum mechanics and quantum field theory. The study of factorized S-matrices, in which many-body scattering factorizes into a product of two-body terms to yield an integrable model, has long been considered the domain of mathematical physics. Many beautiful results have been obtained over several decades for integrable models of this kind, with far reaching implications in both mathematics and theoretical physics. The viewpoint that these were only toy models changed dramatically with brilliant experimental advances in realizing low-dimensional quantum many-body systems in the lab. These recent experiments involve both the traditional setting of condensed matter physics and the trapping and cooling of atoms in optical lattices to engineer and study quasi-one-dimensional systems. In some cases the quantum physics of one-dimensional systems is arguably more interesting than their three-dimensional counterparts, because the effect of interactions is more pronounced when atoms are confined to one dimension. This article provides a brief overview of these ongoing developments, which highlight the fundamental importance of integrability. © 2014 World Scientific Publishing Company.

Wang Z.,Northeastern University China | Yang D.,Northeastern University China | Ma T.,Chongqing University | Sun N.,Jilin Electrical Power Company Ltd
Nonlinear Dynamics | Year: 2014

This work constructs a theoretical framework for the stability analysis of nonlinear fractional-order systems. A new definition, the generalized Caputo fractional derivative, is proposed for the first time. Based on that, the comparison principles for scalar and vector fractional-order systems are constructed, respectively. Furthermore, a sufficient theorem for stability analysis is proved, and how to use this theorem in stabilization is also discussed. Three examples have been presented to illustrate how to use the developed theory to analyze the stability and to design stabilization controllers. With the proposed method, the problems of stabilization and synchronization of the fractional-order chaotic fractional-order systems can be easily solved with linear feedback control. © 2013 Springer Science+Business Media Dordrecht.

Feng G.,amician Delluniversita | Gou Q.,amician Delluniversita | Evangelisti L.,amician Delluniversita | Xia Z.,Chongqing University | Caminati W.,amician Delluniversita
Physical Chemistry Chemical Physics | Year: 2013

The bimolecule acrylic acid-formic acid has been investigated by pulsed jet Fourier transform microwave spectroscopy. The complex adopts two different conformational shapes, according to the cis or trans forms of the acrylic acid moiety. The measurements have been extended to four deuterated and to four 13C (natural abundance) species, and their combinations, for each conformer. These data allowed us to determine the carbon skeleton structures and to size quantitatively the structural effect caused by the OH → OD isotopic substitutions (the Ubbelohde effect).© 2013 the Owner Societies.

Liu Q.,Chongqing University
Jinshu Xuebao/Acta Metallurgica Sinica | Year: 2010

Possible slip and twinning systems and their critical resolved shear stresses of Mg alloys with hcp structure were described. Research works on plastic deformation behavior and micro-mechanism of different kinds of Mg alloys were reviewed. Both microstructure and texture evolutions during different thermomechanical processes, both dynamic and static recrystallization mechanisms of Mg alloys were described and discussed. Deformation and strengthening mechanisms of precipitates hardening Mg alloys were also addressed with emphasis on the interaction between precipitates and twinning/slip.

Huang H.,Chongqing University
Journal of Applied Remote Sensing | Year: 2013

Sparsity preserving projections (SPP) has drawn more and more attention recently. However, the SPP only focuses on the sparse structure but ignores the discriminant information of labeled samples.We proposed a new sparse manifold learning method, called sparse discriminant embedding (SDE), for hyperspectral image (HSI) classification. The SDE utilizes the merits of both sparsity property and manifold structure. It not only preserves the sparse reconstructive relations but also explicitly boosts the discriminant manifold structure of the data, and the discriminating power of the SDE is further improved than the SPP. Experiments on the Flightline C1, Washington DC Mall, and Botswana HSI datasets are performed to demonstrate the effectiveness of the proposed SDE method. © 2013 Society of Photo-Optical Instrumentation Engineers.

Zheng S.,Chongqing University
European Physical Journal C | Year: 2015

A small tensor-to-scalar ratio r may lead to distinctive phenomenology of high-scale supersymmetry. Assuming the same origin of SUSY breaking between the inflation and visible sector, we show model independent features. The simplest hybrid inflation, together with a new linear term for the inflaton field which is induced by a large gravitino mass, is shown to be consistent with all experimental data for r of order $$10^{-5}$$10-5. For superpartner masses far above the weak scale we find that the reheating temperature after inflation might be below the value required by thermal leptogenesis if the inflaton decays to its products perturbatively, but above it if the decay is non-perturbatively instead. Remarkably, the gravitino overproduction can be evaded in such high-scale supersymmetry because of the kinematically blocking effect. © 2015, The Author(s).

Dai J.,Kunming University of Science and Technology | Meng W.,Chongqing University
International Journal of Production Economics | Year: 2015

In this paper we analyze a single-period inventory model where a risk-averse newsvendor makes a joint decision on ordering, pricing and marketing under the CVaR risk measure criterion. The newsvendor can exert marketing effort to enhance market demand. We assume that the newsvendor's marketing effort affects the scale of the demand distribution and hence to model the marketing-dependent demand as a multiplicative form. We characterize sufficient conditions that guarantee existence and uniqueness of the optimal solutions under some mild assumptions on demand distribution, expected demand function and marketing effort cost, which are widely used in the related literature. We show that the optimal order quantity increases in the newsvendor's marketing effort, but the optimal price remains unchanged whether the demand is marketing-dependent or not. Additionally, we explore impact of exogenous parameters, such as unit order cost, salvage value and the newsvendor's risk aversion coefficient, on the optimal decision variables, and find that the optimal marketing effort always keeps the same changing direction with the optimal marketing-independent order quantity as the exogenous parameters change. This suggests that impact of the parameters on the optimal order quantity gets strengthened in the case of marketing-dependent demand. © 2014 Elsevier B.V. All rights reserved.

Wang Y.,Chongqing University of Posts and Telecommunications | Wang Y.,City University of Hong Kong | Wong K.-W.,City University of Hong Kong | Liao X.,Chongqing University | Chen G.,City University of Hong Kong
Applied Soft Computing Journal | Year: 2011

In recent years, various image encryption algorithms based on the permutation-diffusion architecture have been proposed where, however, permutation and diffusion are considered as two separate stages, both requiring image-scanning to obtain pixel values. If these two stages are combined, the duplicated scanning effort can be reduced and the encryption can be accelerated. In this paper, a fast image encryption algorithm with combined permutation and diffusion is proposed. First, the image is partitioned into blocks of pixels. Then, spatiotemporal chaos is employed to shuffle the blocks and, at the same time, to change the pixel values. Meanwhile, an efficient method for generating pseudorandom numbers from spatiotemporal chaos is suggested, which further increases the encryption speed. Theoretical analyses and computer simulations both confirm that the new algorithm has high security and is very fast for practical image encryption. © 2010 Elsevier B.V. All rights reserved.

Long Z.,Chongqing University
Sheng wu yi xue gong cheng xue za zhi = Journal of biomedical engineering = Shengwu yixue gongchengxue zazhi | Year: 2010

In the light of optical theory, we advanc an ultra-wideband impulse radiating antenna (IRA) which is composed of an ellipsoidal reflector and a cone radiator. The high-intensity ultra-short electric pulses radiated by IRA can be transferred into the deep target in tissue non-invasively and be focused effectively. With the focused picosecond electric pulses, the organelles (mitochondria) transmembrane potential shall change to collapse under which the tumor cells will be targetly induced to apoptosis, so the method of non-invasive treatment of tumors would be achieved. Based on the time-domain electromagnetic field theory, the propagation characteristics of picosecond electric pulses were analyzed with and without the context of biological tissue, respectively. The results show that the impulse characteristics of input pulse were maintained and the picosecond electric pulses can keep high resolution in target areas. Meanwhile, because of the dispersive nature of medium, the pulse amplitude of the pulses will attenuate and the pulse width will be broadened.

Li X.-Y.,Southwest Jiaotong University | Wu F.,Southwest Jiaotong University | Jin X.,Chongqing University | Chen W.-Q.,Zhejiang University
Journal of the Mechanics and Physics of Solids | Year: 2015

The present paper is concerned with three-dimensional (3D) coupled field in a transversely isotropic magneto-electro-elastic half space punched by a rigid flat-ended elliptic indenter. Closed form solutions and corresponding numerical results are presented in this work, in a systematic manner. The material in question is transversely isotropic with the axis of symmetry normal to the surface of the half space. The indenter is assumed to be either electrically and magnetically conducting or insulating. Corresponding boundary integral equations (BIEs), to indenter with different magneto-electric properties, are solved by virtue of the method of generalized potential theory. For all four physical cases, corresponding coupled magneto-electro-elastic fields in the half space are obtained. The present analytical solutions indicate that the indentation forces and stiffness may be written as intrinsic combinations of a physical factor and a geometrical factor. The present study is an extension of the previous work on circular punch, and may find applications in guiding future indentation experiments. © 2014 Elsevier Ltd.

Zhou X.,University of Sichuan | Xiao T.,University of Sichuan | Iwama Y.,Tohoku University | Qin Y.,University of Sichuan | Qin Y.,Chongqing University
Angewandte Chemie - International Edition | Year: 2012

Challenging: (+)-gelsemine was synthesized from (R,R)-aziridine 1 in 25 steps with approximately 1% overall yield. A multistep, one-pot enol-oxonium cyclization cascade was used to construct, simultaneously, the E ring, F ring, C3 stereocenter, and C7 quaternary stereocenter. This synthesis using the enol-oxonium cyclization reaction as a key step to make the cage structure has demonstrated the proposed biosynthetic pathway of the gelsemine family. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Huang Y.,Chongqing University | Huang Y.,CAS Institute of Physics | Fang Y.,CAS Institute of Physics | Sun M.,CAS Institute of Physics
Journal of Physical Chemistry C | Year: 2011

In this paper, remote excitation of surface-enhanced Raman scattering (SERS) based on propagating surface plasmon polariton (SPP) on single well-defined crystal Au nanowire with quasi-spherical termini has been reported. Considering the terminal shape dependence of propagating SPP on nanowires, we first study the relationship between polarization of incident laser and emission induced by propagating SPP to acquire best Raman signal at quasi-spherical terminus. This result is confirmed by simulation using finite-difference time-domain method. And then, remote excitation of SERS is achieved when polarization of incident laser was parallel to Au nanowire. © 2011 American Chemical Society.

Liu Y.,University of Washington | Clark M.,University of Washington | Clark M.,University of British Columbia | Zhang Q.,University of Washington | And 5 more authors.
Advanced Energy Materials | Year: 2011

Nanostructured V 2O 5 thin films have been prepared by means of cathodic deposition from an aqueous solution made from V 2O 5 and H 2O 2 directly on fluorine-doped tin oxide coated (FTO) glasses followed by annealing at 500 °C in air, and studied as film electrodes for lithium ion batteries. XPS results show that the as-deposited films contained 15% V 4+, however after annealing all the vanadium is oxidized to V 5+. The crystallinity, surface morphology, and microstructures of the films have been investigated by means of XRD, SEM, and AFM. The V 2O 5 thin film electrodes show excellent electrochemical properties as cathodes for lithium ion intercalation: a high initial discharge capacity of 402 mA h g -1 and 240 mA h g -1 is retained after over 200 cycles with a discharging rate of 200 mA g -1 (1.3 C). The specific energy density is calculated as 900 W h kg -1 for the 1 st cycle and 723 W h kg -1 for the 180 th cycle when the films are tested at 200 mA g -1 (1.3 C). When discharge/charge is carried out at a high current density of 10.5 A g -1 (70 C), the thin film electrodes retain a good discharge capacity of 120 mA h g -1, and the specific power density is over 28 kW kg -1. © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Li X.,Chongqing University
Sheng wu yi xue gong cheng xue za zhi = Journal of biomedical engineering = Shengwu yixue gongchengxue zazhi | Year: 2013

Hepatocellular carcinoma (HCC) is one of the most common human malignant tumors worldwide; it is also hard to prevent its metastasis and recurrence by traditional treatments. Up to now, how to prevent and treat HCC is still a challenging problem in clinic. Cancer stem cells (CSCs) are cells within malignant tumor that possess the capacity to self-renew and differentiate to lead to the heterogeneous lineages of cancer cells that comprise the tumor, and are the root to cause metastasis, recurrence and bad prognosis of the cancer. Targeting CSCs is a novel therapeutic strategy for management and treatment of the cancer. In recent years, targeting intervention on liver cancer stem cells (LCSCs) gradually became a novel strategy for HCC treatment, and some exciting research results in the treatment of HCC were also achieved. In this review, we introduce the biological characteristics of LCSCs and highlight the therapeutic strategies for hepatocellular carcinoma by targeting intervention on LCSCs.

Chen C.R.,Chongqing University | Li M.H.,Northwest University, China
Numerical Functional Analysis and Optimization | Year: 2014

In this article, using the nonlinear scalarization approach by virtue of the nonlinear scalarization function, commonly known as the Gerstewitz function in the theory of vector optimization, Hölder continuity of solution mappings for both set-valued and single-valued cases to parametric vector equilibrium problems is studied. The nonlinear scalarization function is a powerful tool that plays a key role in the proofs, and its main properties (such as sublinearity, continuity, convexity) are fully employed. Especially, its locally and globally Lipschitz properties are provided and the Lipschitz property is first exploited to investigate the Hölder continuity of solutions. © 2014 Copyright Taylor & Francis Group, LLC.

Haiyan T.,Chongqing University
Frattura ed Integrita Strutturale | Year: 2016

Bamboo and wood are the most widely applied and the oldest natural structural materials in the world. Currently, worldwide output of wooden material is 1 billion ton, almost the same as steel. Most of them are used as structure, such as load carrying girder, scaffold, floor and support. Wooden materials and bamboo materials with clear microstructure are composite biomaterials which can be studied under multiple scales. Irregular evolution behaviors of initial defects or damage during loading determines macro mechanical behavior of wooden and bamboo materials. Taking wood and bamboo as test materials, this study explored mechanical characteristics and damage crack behavior of wood and bamboo as well as toughening mechanism. © 2016, Gruppo Italiano Frattura. All rights reserved.

Wang D.H.,Chongqing University | Liao W.H.,Chinese University of Hong Kong
Smart Materials and Structures | Year: 2011

Due to the inherent nonlinear nature of magnetorheological (MR) dampers, one of the challenging aspects for developing and utilizing these devices to achieve high performance is the development of models that can accurately describe their unique characteristics. In this review, the characteristics of MR dampers are summarized according to the measured responses under different conditions. On these bases, the considerations and methods of the parametric dynamic modelling for MR dampers are given and the state-of-the-art parametric dynamic modelling, identification and validation techniques for MR dampers are reviewed. In the past two decades, the models for MR dampers have been focused on how to improve the modelling accuracy. Although the force-displacement behaviour is well represented by most of the proposed dynamic models for MR dampers, no simple parametric models with high accuracy for MR dampers can be found. In addition, the parametric dynamic models for MR dampers with on-line updating ability and the inverse parametric models for MR dampers are scarcely explored. Moreover, whether one dynamic model for MR dampers can portray the force-displacement and force-velocity behaviour is not only determined by the dynamic model itself but also determined by the identification method.

Deng D.,Chongqing University | Kiyoshima S.,Computational Mechanics Inc
Nuclear Engineering and Design | Year: 2010

With the development of computer hardware and software, numerical simulation technology has been widely used to predict welding temperature field, residual stresses and distortion. However, till now the influences of initial stresses induced by the manufacturing process before welding on the welding-induced residual stresses are rarely investigated experimentally and numerically. In the present work, we have developed a computational approach based on thermal elastic plastic FEM to clarify how the initial stresses due to heat treatment affect the welding-induced residual stresses in an austenitic stainless steel pipe. A heat treatment process, which is similar to solution heat treatment, is employed to produce initial stresses in the pipe before welding. After the heat treatment, the laser beam welding is used to perform a girth weld in the middle of the pipe. Through comparing the residual stress distributions after heat treatment and laser beam welding, we have investigated the influence of the initial residual stresses on the welding-induced residual stresses. The numerical results suggest that the initial residual stresses prior to welding have significant effects on the residual stresses after welding in the pipe model. © 2009 Elsevier B.V. All rights reserved.

Xiong W.,Chongqing University
Journal of Applied Physics | Year: 2012

Based on the framework of the effective-mass theory, the Hamiltonians of the electron and hole states of the wurtzite structure in the magnetic field are derived. The obtained Hamiltonians can then be solved by the Bessel function expanding method in which the electron and the hole are assumed to be confined in the infinitely high potential barrier. The conduction and valence subbands are denoted after solving the Schrdinger equation. Several possible low interband transitions are calculated, and the magnetic field is found to split the eight transitions to 18 individual transitions. The optical circularly polarized properties of each transition are also labeled when the magnetic field is applied along the z axis. © 2012 American Institute of Physics.

Zhu D.,Chongqing University | Jane Wang Q.,Northwestern University
Journal of Tribology | Year: 2011

Elastohydrodynamic Lubrication (EHL) is commonly known as a mode of fluid-film lubrication in which the mechanism of hydrodynamic film formation is enhanced by surface elastic deformation and lubricant viscosity increase due to high pressure. It has been an active and challenging field of research since the 1950s. Significant breakthroughs achieved in the last 10-15 years are largely in the area of mixed EHL, in which surface asperity contact and hydrodynamic lubricant film coexist. Mixed EHL is of the utmost importance not only because most power-transmitting components operate in this regime, but also due to its theoretical universality that dry contact and full-film lubrication are in fact its special cases under extreme conditions. In principle, mixed EHL has included the basic physical elements for modeling contact, or hydrodynamic lubrication, or both together. The unified mixed lubrication models that have recently been developed are now capable of simulating the entire transition of interfacial status from full-film and mixed lubrication down to dry contact with an integrated mathematic formulation and numerical approach. This has indeed bridged the two branches of engineering science, contact mechanics, and hydrodynamic lubrication theory, which have been traditionally separate since the 1880s mainly due to the lack of powerful analytical and numerical tools. The recent advancement in mixed EHL begins to bring contact and lubrication together, and thus an evolving concept of Interfacial Mechanics can be proposed in order to describe interfacial phenomena more precisely and collaborate with research in other related fields, such as interfacial physics and chemistry, more closely. This review paper briefly presents snapshots of the history of EHL research, and also expresses the authors' opinions about its further development as a gateway to interfacial mechanics. © 2011 American Society of Mechanical Engineers.

Li X.-H.,Chongqing University
Physical Review A - Atomic, Molecular, and Optical Physics | Year: 2010

We present an efficient entanglement purification protocol with hyperentanglement in which additional spatial entanglement is utilized to purify the two-particle polarization-entangled state. The bit-flip error and phase-flip error can be corrected and eliminated in one step. Two remote parties can obtain maximally entangled polarization states deterministically and only passive linear optics are employed. We also discuss the protocol with practical quantum source and noisy channel. © 2010 The American Physical Society.

The Aux/IAA family genes encode short-lived nuclear proteins that function as transcriptional regulators in auxin signal transduction. Aux/IAA genes have been reported to control many processes of plant development. Our recent study showed that down-regulation of SlIAA15 in tomato reduced apical dominance, altered pattern of axillary shoot development, increased lateral root formation and leaves thickness. The SlIAA15 suppressed lines display strong reduction of trichome density, suggesting that SlIAA15 is involved in trichome formation. Here, we reported that SlIAA15-suppressed transgenic lines display increased number of xylem cells compared to wild-type plants. Moreover, the monoterpene content in trichome exudates are significantly reduced in SlIAA15 down-regulated leaves. The results provide the roles of SlIAA15 in production of volatile compounds in leaf exudates and xylem development, clearly indicating that members of the Aux/IAA gene family can play distinct and specific functions. 

Ye L.,Chongqing University
Communications in Computer and Information Science | Year: 2012

Knapsack problem is a classical NP-Complete problem. In this paper, a DNA computing algorithm is proposed to find out the optimal solution of 0-1 knapsack problem. The DNA encoding method is described to translate the weight and value of items into DNA stands. Then replicated the stands and took the combination of every DNA stand to form double stranded DNA sequences in order to find out the optimal solution. The proposed DNA encoding method is an improvement on the previous ones, and it provides further evidence for the ability of DNA computing to solve numerical optimization problems. © 2012 Springer-Verlag Berlin Heidelberg.

Hong T.,Beihang University | Yu Y.,Chongqing University
Journal of Electromagnetic Waves and Applications | Year: 2011

Strong mutual coupling between closely spaced elements in compact antenna arrays may cause significant system performance degradation. Decoupling networks can be used to compensate for the mutual coupling effect. In this paper, a new compact network structure is proposed to enhance the port isolation between three closely spaced antennas. This 6-port network consists of only a microstrip ring. Transmission lines are used to connect the output ports of the network to the terminals of the three-element array. Open stubs match the input ports of the network to the system impedance. A three-monopole array with the proposed decoupling and matching network was fabricated. The experimental results show that port isolation is achieved for this compact three-monopole array. © 2011 VSP.

Chen Z.,Chongqing University | Xiao H.,Yanshan University
Computational Mechanics | Year: 2012

Fast multipole boundary element methods (FMBEMs) are developed based on the couple of fast multipole algorithm and generalized minimal residual algorithm. The FMBEMs improve the efficiency of conventional BEMs, accelerate the computing, enlarge the solving scale, and it is applied in various engineering fields. The paper tried to do a brief reviewfor the FMBEMs, and focus on the description of basic principles and applications in rolling engineering. The basic principles and main frameworks of two typical methods of FMBEMs (sphere harmonic function multipole BEM and Taylor series multipole BEM) are briefly described, and then the key numerical iterative and preconditioning techniques suitable for the FMBEMs are introduced. The typical numerical examples are presented, including the elasticity problems, the elastic contact problems and the elastoplasticity problems, etc. The validity and effectiveness of FMBEMs are effectively illustrated by engineering analysis examples. The numerical results suggest that the FMBEMs are suitable for the analysis and solution of large scale rolling engineering problems. The implementation process of numerical analysis can provide useful reference for the applications in other engineering fields.

Zhou P.,University of Electronic Science and Technology of China | Wang C.,University of Electronic Science and Technology of China | Ren Y.,Chongqing University | Yang C.,University of Electronic Science and Technology of China | Tian F.,Southwest Jiaotong University
Current Medicinal Chemistry | Year: 2013

The recent focus on protein-protein interaction networks has increasingly been shifted towards the disruption of protein complexes, which either are mediated by the binding of a globular domain in one protein to a short peptide stretch in another, or involve flat, large, and hydrophobic interfaces that classical small-molecule agents are not always ideally suited. Rational design of therapeutic peptides with high affinity targeting such interactions has emerged as a new and promising tool in discovery of potential drug candidates against associated diseases. The design is commonly based on bioinformatics methods or molecular modeling techniques, indirectly exploiting structure-activity relationship at the level of peptide sequence or directly deriving lead entities from protein complex architecture. Here, a newly rising subfield called computational peptidology that focuses on the use of computational and theoretical approaches to treat peptiderelated problems is comprehensively reviewed on the design and discovery of peptide agents targeting protein-protein interactions. We address a systematic discussion on several representative cases in which the computational peptidology is successfully employed to develop peptide therapeutics. Besides, some problems and pitfalls accompanied with the current use of computational methods in peptide modeling and design are also present. © 2013 Bentham Science Publishers.

Luo J.R.,Tsinghua University | Godfrey A.,Tsinghua University | Liu W.,Tsinghua University | Liu Q.,Chongqing University
Acta Materialia | Year: 2012

The twinning behavior of a strongly basal textured magnesium alloy AZ31 plate during warm rolling to a reduction of 9% has been investigated. Analysis of the twin types and twin variants was carried out based on orientation data collected using electron backscatter diffraction. Double twins (corresponding to contraction twinning followed by extension twinning) were the most commonly observed twin type, with more than 70% of the grains examined containing this type of twin. The double twin variant with a 38° misorientation to the original grain orientation was the most frequently observed, with the 30° variant being the next most frequently observed. The twinning variant selection was analyzed using both a modified Schmid factor for rolling and by use of normal strain maps, used to show the compatibility between the normal strains due to twinning and the applied rolling deformation. It was found that the 38° and 30° misorientation double twin variants provide normal strains that are similarly compatible with the applied deformation, with a slight advantage for the 30° variant. Overall, the results show that for rolling deformation external strain accommodation, rather than self-strain accommodation, is the dominant factor in determining the variant types of the double twins formed during warm rolling. © 2012 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Xiong W.,Chongqing University
Journal of Physics D: Applied Physics | Year: 2012

The electronic structure of CdS nanorods doped with manganese ions in the magnetic field is calculated based on the effective-mass theory, the conduction and valence subbands are found to be non-degenerate in Mn-doped CdS nanorods, the split energies of the valence subbands increase as the increment of the concentration of manganese ions. The possible transitions between the six lowest conduction subbands and the eight highest valence subbands are presented, the optical circularly polarized properties of each transition are also labelled. Through the calculation, it is found that the optical transitions can be influenced by the concentration of manganese ions and the applied magnetic field, and the radiative intensity of the transition in Mn-doped CdS nanorods increases with the increase in the manganese ions. © 2012 IOP Publishing Ltd.

Huang Y.,CAS Institute of Physics | Huang Y.,Chongqing University | Fang Y.,CAS Institute of Physics | Yang Z.,Xiamen University | Sun M.,CAS Institute of Physics
Journal of Physical Chemistry C | Year: 2010

In this study, we attempt to experimentally address the question of whether p,p′-dimercaptoazobisbenzene (DMAB) can be produced from p-aminothiophenol (PATP) by surface photochemistry reaction in the junctions of a Ag nanoparticle-molecule-Ag (or Au) film. First, utilizing surface-enhanced Raman scattering (SERS) spectra, we provide experimental and theoretical evidence that DMAB can be produced from PATP by surface photochemistry reaction in the junctions of a Ag nanoparticle-molecule-Ag film. Second, we investigate the SERS spectra utilizing both experimental and theoretical approaches, ultimately revealing that DMAB cannot be produced from PATP in the junctions of a Ag nanoparticle-molecule-Au film. The electromagnetic enhancements are estimated with three-dimensional finite-difference time domain methods, which are about 9 × 105 times in the junctions of Ag nanoparticle-PATP-Ag/Au films. © 2010 American Chemical Society.

Liu H.,Jiangxi Science and Technology Normal University | Liu G.,Jiangxi Science and Technology Normal University | Pu S.,Jiangxi Science and Technology Normal University | Wang Z.,Chongqing University
Organic and Biomolecular Chemistry | Year: 2013

A novel and unexpected reaction of 2-alkynylbenzaldoximes with ketenes in the presence of silver triflate (10 mol%) under mild conditions is discovered. This reaction proceeds through 6-endo-cyclization, [3 + 2] cycloaddition, and rearrangement, leading to isoquinoline derivatives in moderate to good yields. © 2013 The Royal Society of Chemistry.

Meng F.M.,Chongqing University
Optics and Laser Technology | Year: 2013

The influence of cavitation in a lubricant under different conditions on tribological performances of a textured surface was investigated numerically. The investigation is carried out using dimples with divergent-convergent shape under the conditions of different dimple distributions, dimple depths, and different width to length ratio of solution domain (k). In doing so, an extended Reynolds equation is used to solve pressure, incorporating cavitation effect and elastic deformation of the textured surface evaluated with continuous convolution fast Fourier transform (CC-FFT). Numerical results show that the cavitation can increase the load-carrying capacity, and decrease the friction force and further the friction coefficient for tribological pairs. For the metioned dimples, whether the k value or the dimple depth increases, the cavitated area will approach a stable value. The above influences depend on the dimple distribution and its depth, or the k value. Meanwhile, some of the above conclusions are also validated with the experimental results. © 2012 Elsevier Ltd.

Cong W.,Rensselaer Polytechnic Institute | Liu F.,Rensselaer Polytechnic Institute | Liu F.,Chongqing University | Wang C.,Rensselaer Polytechnic Institute | Wang G.,Rensselaer Polytechnic Institute
Optics Express | Year: 2014

Imaging depth of optical microscopy has been fundamentally limited to millimeter or sub-millimeter due to strong scattering of light in a biological sample. X-ray microscopy can resolve spatial details of few microns deep inside a sample but contrast resolution is inadequate to depict heterogeneous features at cellular or sub-cellular levels. To enhance and enrich biological contrast at large imaging depth, various nanoparticles are introduced and become essential to basic research and molecular medicine. Nanoparticles can be functionalized as imaging probes, similar to fluorescent and bioluminescent proteins. LiGa 5O8:Cr3+ nanoparticles were recently synthesized to facilitate luminescence energy storage with x-ray pre-excitation and subsequently stimulated luminescence emission by visible/near-infrared (NIR) light. In this paper, we propose an x-ray micromodulated luminescence tomography (XMLT, or MLT to be more general) approach to quantify a nanophosphor distribution in a thick biological sample with high resolution. Our numerical simulation studies demonstrate the feasibility of the proposed approach. © 2014 Optical Society of America.

Jian X.,Chongqing University
International Journal of Physical Sciences | Year: 2011

In this paper, an active sliding mode controller is presented for a class of master-slave antisynchronization of uncertain Rikitake systems. Uncertainties are considered in linear and nonlinear parts of the Rikitake systems. Analysis of the stability for the proposed method is derived based on the Lyapunov stability theory. Numerical simulations are performed to evaluate effectiveness of the analytical results. © 2011 Academic Journals.

The FeCoNiB thin films with excellent soft magnetic properties were synthesized by radio frequency (RF) magnetron sputtering. Effects of RF noise suppression on the microstrip line using FeCoNiB films were investigated. It is found that FeCoNiB films with appropriate low Ni content exhibit excellent noise suppression properties including a maximum attenuation of 17.4 dB. Owing to the eddy current loss, the ferromagnetic resonance loss and L-C resonance, the intensity and frequency of RF signal attenuation can be adjusted by the geometric dimension of magnetic thin films and dielectric layers. These results reveal that the presented thin films possess high potential for RF noise suppressors. © 2013 American Institute of Physics.

Li L.,Tongji University | Li L.,University of California at Berkeley | Gao N.,Tongji University | Deng Y.,Montclair State University | And 2 more authors.
Water Research | Year: 2012

Algae organic matters (AOM), including intracellular organic matters (IOM) and extracellular organic matters (EOM), are causing numerous water quality issues, among which formation of disinfection byproducts (DBPs) and odor & taste (O&T) compounds are of particular concern. In this study, physiochemical properties of IOM and EOM of Microcystic aeruginosa under an exponential growth phase (2.01×10 11/L) were comprehensively characterized. Moreover, the yields of DBPs during AOM disinfection and O&T-causing compounds were quantified. Hydrophilic organic matters accounted for 86% and 63% of DOC in IOM and EOM, respectively. Molecular weight (MW) fractions of IOM in <1kDa, 40-800kDa, and >800kDa were 27%, 42%, and 31% of DOC, respectively, while EOM primarily contained 1-100kDa molecules. Besides, a low SUVA (0.84L/mgm) and the specific fluorescence spectra suggested that AOM (especially IOM) was principally comprised of protein-like substances, instead of humic-like matters. The formation potentials of chloroform, chloroacetic acid, and nitrosodimethylamine were 21.46, 68.29 and 0.0096μg/mgC for IOM, and 32.44, 54.58 and 0.0189μg/mgC for EOM, respectively. Furthermore, the dominant O&T compound produced from EOM and IOM were 2-MIB (68.75ng/mgC) and β-cyclocitral (367.59ng/mgC), respectively. Of note, dimethyltrisulfide became the prevailing O & T compound following anaerobic cultivation. © 2011 Elsevier Ltd.

Chen G.,Chongqing University | Lewis F.L.,University of Texas at Arlington | Xie L.,Nanyang Technological University
Automatica | Year: 2011

This paper investigates the finite-time distributed consensus problem for multi-agent systems using a binary consensus protocol and the pinning control scheme. Compared with other consensus algorithms which need the complete state or output information of neighbors, the proposed algorithm only requires sign information of the relative state measurements, that is, the differences between a node's state and that of its neighbors. This corresponds to only requiring a single-bit quantization error relative to each neighbor. This signum protocol is realistic in terms of observed behavior in animal groups, where relative motion is determined not by full time-signal measurements, but by coarse estimates of relative heading differences between neighbors. The signum protocol does not require explicit measurement of time signals from neighbors, and hence has the potential to significantly reduce the requirements for both computation and sensing. Analysis of discontinuous dynamical systems is used, including the Filippov solutions and set-valued Lie derivative. Based on the second-order information on the evolution of Lyapunov functions, the conditions that guarantee the finite-time consensus for the systems are identified. Numerical examples are given to illustrate the theoretical results. © 2011 Elsevier Ltd. All rights reserved.

Brodsky S.J.,SLAC | Wu X.-G.,SLAC | Wu X.-G.,Chongqing University
Physical Review Letters | Year: 2012

It is conventional to choose a typical momentum transfer of the process as the renormalization scale and take an arbitrary range to estimate the uncertainty in the QCD prediction. However, predictions using this procedure depend on the renormalization scheme, leave a nonconvergent renormalon perturbative series, and moreover, one obtains incorrect results when applied to QED processes. In contrast, if one fixes the renormalization scale using the principle of maximum conformality (PMC), all nonconformal {β i} terms in the perturbative expansion series are summed into the running coupling, and one obtains a unique, scale-fixed, scheme-independent prediction at any finite order. The PMC scale μRPMC and the resulting finite-order PMC prediction are both to high accuracy independent of the choice of initial renormalization scale μRinit, consistent with renormalization group invariance. As an application, we apply the PMC procedure to obtain next-to-next-to-leading-order (NNLO) predictions for the tt̄-pair production at the Tevatron and LHC colliders. The PMC prediction for the total cross section σ tt̄ agrees well with the present Tevatron and LHC data. We also verify that the initial scale independence of the PMC prediction is satisfied to high accuracy at the NNLO level: the total cross section remains almost unchanged even when taking very disparate initial scales μRinit equal to m t, 20m t, and √s. Moreover, after PMC scale setting, we obtain AFBtt̄ 12.5%, AFBpp̄ 8.28% and AFBtt̄(M tt̄>450GeV) 35.0%. These predictions have a 1σ deviation from the present CDF and D0 measurements; the large discrepancy of the top quark forward-backward asymmetry between the standard model estimate and the data are, thus, greatly reduced. © 2012 American Physical Society.

Yang B.,Princeton University | Hu Z.-X.,Princeton University | Hu Z.-X.,Chongqing University | Papic Z.,Princeton University | Haldane F.D.M.,Princeton University
Physical Review Letters | Year: 2012

We construct model wave functions for the collective modes of fractional quantum Hall systems. The wave functions are expressed in terms of symmetric polynomials characterized by a root partition that defines a "squeezed" basis, and show excellent agreement with exact diagonalization results for finite systems. In the long wavelength limit, we prove that the model wave functions are identical to those predicted by the single-mode approximation, leading to intriguing interpretations of the collective modes from the perspective of the ground-state guiding-center metric. © 2012 American Physical Society.

Yi L.,Chongqing University
International Journal of Advancements in Computing Technology | Year: 2011

Through establishing the fuzzy DEA model and introducing in the field of real estate investment risk evaluation, this paper offers a new method to carry out relatively effective evaluation when the inputs and outputs of the DMU are the special fuzzy numbers (R L - model). Finally, verifying the feasibility of the model through a specific example. The model needn't determine the weight of the evaluation indexes that reduces the subjective evaluation, thus, the results are more reasonable.

Zhang Y.,Henan University of Technology | Liu C.,Henan University of Technology | Song Y.,Chongqing University
Journal of the Franklin Institute | Year: 2013

This paper investigates the problem of finite-time H∞ filtering for one class of discrete-time Markovian jump systems with time-varying norm-bounded disturbance. Firstly, the filtering error dynamic system is constructed based on an H∞ filter with or without the control input. Then, an H∞ filtering is designed to ensure stochastic finite-time boundedness of the resulting filtering error system and satisfying a prescribed H∞ attenuation level for the filtering error system in the given finite-time interval. Sufficient criteria on the stochastic H∞ finite-time boundedness are established in terms of linear matrix inequalities with a fixed parameter. As an auxiliary result, we also tackle the problem of finite-time H∞ filtering for discrete-time Markovian jump systems without the control input and provide sufficient conditions on finite-time H∞ filtering for the family of discrete-time Markovian jump systems. Finally, numerical examples are presented to show the validity of the developed techniques. © 2013 The Franklin Institute.

Wu X.-G.,Chongqing University | Huang T.,CAS Institute of High Energy Physics
Physical Review D - Particles, Fields, Gravitation and Cosmology | Year: 2011

The meson-photon transition form factors γγ*→P (P stands for π, η and η′) provide strong constraints on the distribution amplitudes of the pseudoscalar mesons. In this paper, these transition form factors are calculated under the light-cone perturbative QCD approach, in which both the valence and nonvalence quarks' contributions have been taken into consideration. To be consistent, a unified wave function model is adopted to analyze these form factors. It is shown that with the proper charm component fη′c∼-30MeV and a moderate DA with B∼0.30, the experimental data on Q2Fηγ(Q2) and Q2F η′γ(Q2) in the whole Q2 region can be explained simultaneously. Furthermore, a detailed discussion on the form factors' uncertainties caused by the constituent quark masses mq and m s, the parameter B, the mixing angle, and fη′c are presented. It is found that, by adjusting these parameters within their reasonable regions, one can improve the form factor to a certain degree but cannot solve the puzzle for Q2Fπγ(Q2), especially to explain the behavior of the π-γ form factor within the whole Q2 region consistently. We hope further experimental data on these form factors in the large Q2 region can clarify the present situation. © 2011 American Physical Society.

Wu S.,Chongqing University | Wu S.,Beihang University | Wang C.,Beihang University | Cui Y.,Beijing Solar Energy Research Institute Co.
Applied Surface Science | Year: 2014

Bismuth oxychloride (BiOCl) granular and flake-like films with specific {0 0 1} crystal facets are synthesized by a facile hydrolysis route. The percentage of reactive {0 0 1} facets is up to 97.36% in granular film and 91.69% in flake-like film, respectively. It is found that the synthesized granular film is composed by the nano grains with average size around 5-10 nm, but the flake-like film contains the flakes originated from the large nano crystals. The percentage of the {0 0 1} reactive facets and morphology of the BiOCl film can be tuned by adjusting the concentration or the pH value of the solution during the synthesis process, companied with the appearance of the (1 0 1), (1 0 2), and (1 1 0) facets. The formation mechanism of {0 0 1}-preferential orientation has been rationally explained in terms of crystal growth habit and dynamics. Photocatalytic degradation of RhB dye has been observed under UV light, representing that the flake-like film with {0 0 1} facets preferred orientation exhibits excellent photoactivity. © 2013 Elsevier B.V.

Huang H.,Chongqing University | Kauffman R.J.,Arizona State University
Electronic Commerce Research and Applications | Year: 2011

The generalized second-price auction mechanism is commonly used in research in the context of keyword advertising slot auctioning. The mechanism sets the clearing prices for advertising slots on a search engine's Web pages such that the advertiser will pay what was bid for the next lower advertising slot each time their own higher-ranked hyperlink is clicked. It also assigns advertising slots in the descending order of advertisers' bid prices. Those advertisers who bid the highest prices are given the most attractive sponsored advertising slots at the top of the Web page, where the click-through rates have been shown to be the highest. We explore several issues with this auction mechanism for the sponsored keyword advertising slot context. They include: the distributional assumptions for the click-through rate; sponsored keyword advertising slot valuation over time; participation and click-stream fees and the role of a two-part tariff; alternative advertiser bidding strategies; and the design goals of sponsored keyword advertising slot auctions. We draw a number of conclusions for theory and practice. © 2009 Elsevier B.V. All rights reserved.

Sun D.,Chongqing University
Journal of Computational and Nonlinear Dynamics | Year: 2016

A method for trajectory tracking accuracy analysis of a two-link flexible manipulator with lubricated revolute joint involving interval uncertainty is presented. In this method, first, fuzzy self-tuning proportion integration differentiation (PID) control is applied to track the desired tip trajectory of the manipulator. The absolute nodal coordinate formulation (ANCF) is employed for the finite element discretization of the flexible manipulator. And lubricated revolute joint is modeled based on the infinitely short journal bearing with Gümbel conditions. Second, uncertainty of clearance size is considered, and interval analysis method is applied. Numerical simulation is posted to investigate the cushioning effect of lubricants on the clearance and influence of uncertainty on control accuracy of the manipulator. The results show that the lubricants can improve the stability of motion and operation precision of the manipulator; however, uncertainty of the manipulator may reduce the control accuracy of the manipulator. Copyright © 2016 by ASME.

Azam A.,Dar Al Uloom University | Qiang F.,Chongqing University
International Journal of Electronic Business | Year: 2014

Some of the most electrifying advances in our economy right away are in the realm of electronic commerce. However, many issues associated with online world still pose serious challenges to the growth of electronic commerce and affect consumer behaviour to purchase online. In this study, we test constructs from behavioural study (decomposed theory of planned behaviour (DTPB)) and online retailer ethics (consumers' perception of online retailing ethics (CPEOR)) in an integrated theoretical framework of online consumer behaviour. Exclusively, we examine how attitude, subjective norms, perceived behavioural control (PBC) and CPEOR influence online consumers' intention to purchase online and actual purchase behaviour. An empirical investigation of online consumers' behaviour in China was conducted. Forward logistic regression was used for data analysis and results showed substantial support for most of the hypotheses proposed. Managerial implications and contributions of the study were also discussed. © 2014 Inderscience Enterprises Ltd.

Liu M.,Chongqing University | Chiang K.S.,City University of Hong Kong
Optics Express | Year: 2010

It is known that a decoupled two-core fiber can prevent monochromatic light at a specific wavelength (the decoupling wavelength) launched into one core from coupling to the other core. In this paper, we show that a pulse at the decoupling wavelength launched into one core of such a fiber inevitably splits into two pairs of pulses propagating in the two cores along the fiber. The minimum distance required for pulse splitting to be visible is inversely proportional to the coupling-coefficient dispersion in the fiber and linearly proportional to the pulse width. It would take only several centimeters of a recently demonstrated decoupled two-core photonic-bandgap fiber to observe the pulse-splitting effect with a 100-fs pulse. We also study the effects of self-phase modulation on the pulse propagation dynamics in a decoupled two-core fiber in both the normal and anomalous dispersion regimes. © 2010 Optical Society of America.

Moncayo-Martinez L.A.,University of Exeter | Zhang D.Z.,University of Exeter | Zhang D.Z.,Chongqing University
International Journal of Production Economics | Year: 2011

This paper proposes a new approach to determining the Supply Chain (SC) design for a family of products comprising complex hierarchies of subassemblies and components. For a supply chain, there may be multiple suppliers that could supply the same components as well as optional manufacturing plants that could assemble the subassemblies and the products. Each of these options is differentiated by a lead-time and cost. Given all the possible options, the supply chain design problem is to select the options that minimise the total supply chain cost while keeping the total lead-times within required delivery due dates. This work proposes an algorithm based on Pareto Ant Colony Optimisation as an effective meta-heuristic method for solving multi-objective supply chain design problems. An experimental example and a number of variations of the example are used to test the algorithm and the results reported using a number of comparative metrics. Parameters affecting the performance of the algorithm are investigated. © 2010 Elsevier B.V. All rights reserved.

Wu X.-G.,Chongqing University | Huang T.,CAS Institute of High Energy Physics
Physical Review D - Particles, Fields, Gravitation and Cosmology | Year: 2010

The new BABAR data on the pion-photon transition form factor arouses people's interest for the determination of the pion distribution amplitude. To explain the data, we take both the leading valence quark state's and the nonvalence quark state's contributions into consideration, where the valence quark part up to next-to-leading order is presented and the nonvalence quark part is estimated by a phenomenological model based on its limiting behavior at both Q2→0 and Q2→. Our results show that to be consistent with the new BABAR data at the large Q2 region, a broader amplitude other than the asymptoticlike pion distribution amplitude should be adopted. The broadness of the pion distribution amplitude is controlled by a parameter B. It has been found that the new BABAR data at low and high energy regions can be explained simultaneously by setting B to be around 0.60, in which the pion distribution amplitude is closed to the Chernyak-Zhitnitsky form.

Wang X.,Nanchang University | Wang Z.,Chongqing University
Tetrahedron | Year: 2014

A novel silver-catalyzed tandem reaction of 2-alkynylbenzaldoximes with H-phosphinate esters, and H-phosphine oxides has been developed, providing a general and powerful tool for the synthesis of various 1-phosphorylated isoquinolins in moderate to excellent yield. This reaction proceeded smoothly to construct C-N and C-P bonds in one-pot with good functional group tolerance under mild conditions. © 2014 Elsevier Ltd. All rights reserved.

Ye J.,Chongqing University of Technology | Ye J.,Chongqing University | Jinju Z.,Ningbo University of Technology
Materials Letters | Year: 2014

Rare earth doped Y5Mo2O12 has been prepared by a solid-state reaction at 650 C. For Eu3+ single-doped Y5Mo2O12, the luminescence intensity changes with the concentration of Eu3+ ions, and Y5Mo 2O12: 0.5Eu3+ exhibits the most intense red-emission under near UV excitation. For the Eu3+, Sm3+ co-doped system usnder 405 nm excitation responsible for the 6H 5/2→4K11/2 transition of Sm3+, the f-f transitions of both Eu3+ and Sm3+ are observed in photoluminescence spectra and the intensities of the main emission line ( 5D0→7F2 transition of Eu 3+ at 612 nm) are strengthened owing to the energy transition from Sm3+ to Eu3+. The energy transfer from Sm3+ ions to Eu3+ ions is to be proved by comparing the luminescence intensity of Eu3+ ions single doped sample with that of Eu 3+ and Sm3+ co-doped sample. The luminescence is improved owing to Sm3+ ions' introduced into Y5Mo2O 12: Eu3+ and luminescence intensities are about 7 times under 272 nm excitation and about 1.5 times under 403 nm excitation. © 2013 Elsevier B.V.

Li B.L.,Chongqing Three Gorges University | Chen L.X.,Chongqing Three Gorges University | Zou H.L.,Chongqing Three Gorges University | Lei J.L.,Chongqing University | And 2 more authors.
Nanoscale | Year: 2014

Electrochemically induced Fenton (electro-Fenton) reaction was used for efficient and controllable preparation of hydroxyl radicals, leading to the generation of luminescent quantum dots through etching of as-exfoliated MoS 2 nanosheets. Morphologic changes of MoS2 nanosheets during the electro-Fenton reaction were monitored using transmission electron microscopy, showing that etching of MoS2 nanosheets induced by hydroxyl radicals resulted in rapid homogeneous fracturing of the sheets into small dots via a transition of nanoporous morphology. The as-generated dots with vertical dimensional thickness of ca. 0.7 nm and plane size of ca. 5 nm were demonstrated to be MoS2 quantum dots (MoS2-QDs), and their photoluminescence properties were explored based on quantum confinement, edge effect, and intrinsic characteristics. Moreover, the degree of etching and the concomitant porosity of MoS2 nanosheets could be conveniently tuned via the electro-Fenton reaction time, resulting in a new morphology of nanoporous MoS2 nanosheets, with potential new applications in various significant areas. © 2014 the Partner Organisations.

Liu S.,Northwestern University | Liu S.,Caterpillar Inc. | Jin X.,Northwestern University | Wang Z.,Northwestern University | And 3 more authors.
International Journal of Plasticity | Year: 2012

Modern engineering design often faces severe challenges in accommodating impurities and imperfections of materials in the presence of considerable thermal expansion and plastic deformation. Based on micromechanics, a versatile and effective approach for such non-linear problems can be conceived by employing an inclusion model. This paper reports on the derivation of explicit integral kernels for the elastic fields due to eigenstrains in an elastic half-space. The domain integrations of these kernels result in analytical solutions to stresses and deformations. After dividing each general kernel into four groups, the integration is resolved into three-dimensional convolutions and correlations, which can be numerically processed with algorithms based on fast Fourier transform (FFT) to enable efficient and accurate numerical computations. The analytical solution corresponding to a cuboidal inclusion (a rectangular parallelepiped domain) is obtained in an explicit closed-form and is utilized to determine influence coefficients. The present solution and numerical implementation can be used as building blocks for analyzing arbitrarily distributed thermal strains, plastic strains and material inhomogeneities, as demonstrated by solving an illustrative example of elasto-plastic contact. © 2012 Elsevier Ltd. All rights reserved.

Zhang X.,Hong Kong Polytechnic University | Shen L.,Chongqing University | Zhang L.,Harbin Institute of Technology
Renewable and Sustainable Energy Reviews | Year: 2013

The generation of significant amount of emissions from building construction process has led the promotion of controlling emissions as an important strategy for implementing sustainable development principles in the built environment. The emissions incurred during various stages include carbon dioxide, methane, nitrous oxide, sulphur dioxide, carbon monoxide, nitrogen oxide, non methane volatile organic compounds and particulate matter. This paper conducts the life cycle assessment of the air emissions by using a particular case to examine emissions during construction stage. This study examines the emissions sources in each of the six stages and presents an inventory analysis method to measure air emissions to quantify the air emissions during the six life cycle stages for buildings. This method can help evaluating the impacts of implementing a building on the air quality, thus actions can be taken in early stages to reduce the environmental impacts during building life cycle. A case study is presented to demonstrate the practical application of the method with reference to the building practices for all life cycle stages in Hong Kong. © 2012 Elsevier Ltd.

Liu H.,Chongqing University of Posts and Telecommunications | Nan H.,Chongqing University
Optics and Laser Technology | Year: 2013

In this paper, a color image encryption algorithm is designed by use of chaos-based cyclic shift and multiple-order discrete fractional cosine transform (MODFrCT). The RGB components of the color image are vertically combined and then simultaneously scrambled by chaos-based cyclic shift to make these three components affect each other. The scrambled RGB components are separately transformed with the MODFrCT, whose orders are determined by the Chirikov standard chaotic map. Based on chaotic inherent properties, the corresponding keys are highly sensitive. At the same time, the transmission of the cipher image is very fast since the DFrCT is a reality preserving transform. Simulation results proved the validity of the proposed algorithm. © 2013 Elsevier Ltd.

Sun W.,Princeton University | Chen Z.,Peking University | Gou X.,Chongqing University | Ju Y.,Princeton University
Combustion and Flame | Year: 2010

A direct path flux analysis (PFA) method for kinetic mechanism reduction is proposed and validated by using high temperature ignition, perfect stirred reactors, and steady and unsteady flame propagations of n-heptane and n-decane/air mixtures. The formation and consumption fluxes of each species at multiple reaction path generations are analyzed and used to identify the important reaction pathways and the associated species. The formation and consumption path fluxes used in this method retain flux conservation information and are used to define the path indexes for the first and the second generation reaction paths related to a targeted species. Based on the indexes of each reaction path for the first and second generations, different sized reduced chemical mechanisms which contain different number of species are generated. The reduced mechanisms of n-heptane and n-decane obtained by using the present method are compared to those generated by the direct relation graph (DRG) method. The reaction path analysis for n-decane is conducted to demonstrate the validity of the present method. The comparisons of the ignition delay times, flame propagation speeds, flame structures, and unsteady spherical flame propagation processes showed that with either the same or significantly less number of species, the reduced mechanisms generated by the present PFA are more accurate than that of DRG in a broad range of initial pressures and temperatures. The method is also integrated with the dynamic multi-timescale method and a further increase of computation efficiency is achieved. © 2010 The Combustion Institute.

Xin Y.,Chongqing University | Hu T.,City University of Hong Kong | Chu P.K.,City University of Hong Kong
Journal of the Electrochemical Society | Year: 2010

In this work, the degradation behavior of AZ91 magnesium alloy in five solutions including phosphate buffering solution (PBS), 0.9% NaCl solution, simulated body fluid (c-SBF), Hank's solution, and Dulbecco's modified eagle medium (DMEM) are systematically investigated. Our results show that AZ91 magnesium alloy exhibits a dramatically different degradation behavior in the five solutions. The concentration of buffering agents and the content of hydrocarbonates in test solutions primarily affect the degradation performance, especially the degradation behavior during the early stage. In DMEM and c-SBF with higher contents of buffering agents, the sample shows much more negative corrosion potentials compared to those in Hank's solution, 0.9% NaCl solution, and PBS. The initial degradation rates in DMEM and c-SBF are similar and much higher than those in PBS, 0.9% NaCl, and Hank's solution. Rapid reaction of OH- with the large amount of buffers in DMEM and c-SBF dramatically promotes transformation from Mg to Mg2+, constituting the main reason for the high degradation rates. Distinct corrosion morphology and corrosion products are present on the samples exposed to the five test solutions. Therefore, the proper selection of test solution with similar buffering capability and similar ingredients as biological fluids is imperative to the investigation of the degradation behavior of biomedical magnesium alloys. © 2010 The Electrochemical Society.

Pi J.,Chongqing University
Sheng wu yi xue gong cheng xue za zhi = Journal of biomedical engineering = Shengwu yixue gongchengxue zazhi | Year: 2013

An accurate segmentation of vascular systems is fundamental for many medical applications. In this paper, we propose a 3D vessel enhancement and extraction method. It is based on the analysis of Hessian matrix and Gaussian mixture model-expectation-maximization (GMM-EM) algorithm. Firstly, tube-like vessels were detected and enhanced based on the Hessian matrix eigenvalues. And then, the vascular system was segmented, and then a rough system was obtained with GMM-EM. Hessian-based filters were found to be sensitive to noise and sometimes gave discontinued vessels. Hence, we utilized the closing operation to avoid discontinuity and a 3D-filter on the segmented vessels to reduce noise brought by the contrast agent. Finally, a searching method based on spatial connected area is presented to connect the vascular system in 3D. The experimental results illustrated the efficiency of the method for 3D liver vessel segmentation proposed in this paper.

Liang W.,Harbin Institute of Technology | Liang W.,Chongqing Jiaotong University | Murakawa H.,Osaka University | Deng D.,Chongqing University
Materials and Design | Year: 2015

In this study, an advanced computational approach with considering moving heat source, temperature-dependent material properties, strain-hardening and annealing effect was developed to predict welding temperature field, residual stress distribution and deformation in multi-pass welded joints. The welding residual stress distributions in austenitic stainless steel thick-plate multi-pass joints performed by the different deposition patterns and different deposition directions were simulated through using the developed computational procedure. Based on the numerical results, the features of residual stress distribution near the weld end-start location were examined. Meanwhile, experiments were carried out to measure the welding residual stress distributions in two mock-ups. The numerical results are generally in a good agreement with the experimental measurements. Both experiment and numerical model show that the distribution of welding residual stress near the weld end-start location has an apparent discontinuous feature. The research results indicate that deposition pattern has a significant influence on welding residual stress, and it not only can change the distribution shape of residual stress but also can alter the peak value of residual stress. Under the condition of identical deposition pattern, the distribution of welding residual stress seems not sensitive to deposition direction. © 2014 Elsevier Ltd.

Deng D.,Chongqing University | Murakawa H.,Osaka University
Computational Materials Science | Year: 2013

When medium carbon steel or alloy steel with sufficient carbon equivalent is joined by fusion welding process, solid-state phase transformation has significant influences on the formation of welding residual stress. To predict welding residual stress in such steels using numerical simulation method, the coupling of thermo-metallurgical-mechanical behaviors should be carefully considered. It has been recognized that three factors related to solid-state phase transformation potentially affect the formation of welding residual stress. These three factors are volume change caused by austenite-martensite (bainite) transformation, mechanical properties variation due to microstructure change and transformation induced plasticity. In this study, a computational approach was developed to predict welding residual stress in low temperature transformation steel with considering phase transformation. The main objective is to examine the influence of transformation induced plasticity on the welding residual stress by means of the developed numerical method. The conclusions drawn by the present work potentially have important directive to modeling welding residual stress field. © 2013 Elsevier B.V. All rights reserved.

He X.,Southwest University | Li C.,Southwest University | Huang T.,Texas A&M University at Qatar | Li C.,University of Ballarat | Huang J.,Chongqing University
IEEE Transactions on Neural Networks and Learning Systems | Year: 2014

In this brief, based on the method of penalty functions, a recurrent neural network (NN) modeled by means of a differential inclusion is proposed for solving the bilevel linear programming problem (BLPP). Compared with the existing NNs for BLPP, the model has the least number of state variables and simple structure. Using nonsmooth analysis, the theory of differential inclusions, and Lyapunov-like method, the equilibrium point sequence of the proposed NNs can approximately converge to an optimal solution of BLPP under certain conditions. Finally, the numerical simulations of a supply chain distribution model have shown excellent performance of the proposed recurrent NNs. © 2013 IEEE.

Ding B.,Chongqing University
Asian Journal of Control | Year: 2010

This paper investigates the parameter-dependent open-loop model predictive control (PDOLMPC) scheme for systems with a polytopic uncertainty description. PDOLMPC parameterizes the infinite horizon control moves into a number of free control moves followed by a single state feedback law. The free control moves (excluding the first one) are parameter dependent and constructed upon all of the extreme realizations of the uncertainty before the switching horizon N. Our primary contribution is to point out that this PDOLMPC is a relaxed version of the feedback MPC. Thus, some properties of nominal MPC, such as enhancement of optimality and enlargement of region of attraction by increasing the switching horizon, can be inherited in PDOLMPC. These properties are theoretically important for robust MPC and a simulation example is given for demonstration. © 2009 John Wiley and Sons Asia Pte Ltd and Chinese Automatic Control Society.

Bu F.,Environmental Protection Bureau of Fengjie County | Xu X.,Chongqing University
Environmental Monitoring and Assessment | Year: 2013

The objective of the study was to treat eutrophic river water using floating beds and to identify ideal plant species for design of floating beds. Four parallel pilot-scale units were established and vegetated with Canna indica (U1), Accords calamus (U2), Cyperus alternifolius (U3), and Vetiveria zizanioides (U4), respectively, to treat eutrophic river water. The floating bed was made of polyethylene foam, and plants were vegetated on it. Results suggest that the floating bed is a viable alternative for treating eutrophic river water, especially for inhibiting algae growth. When the influent chemical oxygen demand (COD) varied from 6.53 to 18.45 mg/L, total nitrogen (TN) from 6.82 to 12.25 mg/L, total phosphorus (TP) from 0.65 to 1.64 mg/L, and Chla from 6.22 to 66.46 g/m3, the removal of COD, TN, TP, and Chla was 15.3 %-38.4 %, 25.4 %-48.4 %, 16.1 %-42.1 %, and 29.9 %-88.1 %, respectively. Ranked by removal performance, U1 was best, followed by U2, U3, and U4. In the floating bed, more than 60 % TN and TP were removed by sedimentation; plant uptake was quantitatively of low importance with an average removal of 20.2 % of TN and 29.4 % of TP removed. The loss of TN (TP) was of the least importance. Compared with the other three, U1 exhibited better dissolved oxygen (DO) gradient distributions, higher DO levels, higher hydraulic efficiency, and a higher percentage of nutrient removal attributable to plant uptake; in addition, plant development and the volume of nutrient storage in the C. indica tissues outperformed the other three species. C. indica thus could be selected when designing floating beds for the Three Gorges Reservoir region of P. R. China. © 2013 Springer Science+Business Media Dordrecht.

Yan H.,Chongqing University
Advances in Information Sciences and Service Sciences | Year: 2012

The Intelligent lighting system is the traditional lighting art combined with wireless sensor network, making lamp lightings interconnected with each other in the form of radio waves. By running a computer algorithm in the wireless sensor networks tiny nodes, the display of light effects can be controlled. What's more, the system can monitor the changes of the environment, including someone going across by, do many reaction effects to the changes using a PWM (Pulse Width Modulation) algorithm, and diffuse it to all the light-nodes according to the genetic simulation algorithm, which will be descripted in this paper. Because of the genetic simulation algorithm, you can easily increase or decrease the quantity of the light-nodes in the system.

Li X.-H.,Chongqing University | Li X.-H.,Wilfrid Laurier University
Wuli Xuebao/Acta Physica Sinica | Year: 2015

Quantum secure direct communication (QSDC) is one of the most important branches of quantum communication. In contrast to the quantum key distribution (QKD) which distributes a secure key between distant parties, QSDC directly transmits secret message instead of sharing key in advance. To establish a secure QSDC protocol, on the one hand, the security of the quantum channel should be confirmed before the exchange of the secret message. On the other hand, the quantum state should be transmitted in a quantum data block since the security of QSDC is based on the error rate analysis in the theories on statistics. Compared with the deterministic quantum key distribution (DQKD) which can also be used to transmit deterministic information, QSDC schemes do not need extra classical bits to read the secret message except for public discussion. In this article, we introduce the basic principles of QSDC and review the development in this field by introducing typical QSDC protocols chronologically. The first QSDC protocol was proposed by Long and Liu, which can be used to establish a common key between distant parties. In their scheme, the method for transmitting quantum states in a block by block way and in multiple steps was proposed and the information leakage before eavesdropping detection was solved. Subsequently, Deng et al. presented two pioneering QSDC schemes, an entangled-state-based two-step QSDC scheme and a single-photon-state-based quantum one-time pad scheme, in which the basic principle and criteria for QSDC were pointed out. From then on, many interesting QSDC schemes have been proposed, including the high-dimension QSDC scheme based on quantum superdense coding, multi-step QSDC scheme based on Greenberger-Horne-Zeilinger states, QSDC scheme based on quantum encryption with practical non-maximally entangled quantum channel, and so on. We also introduce the anti-noise QSDC schemes which were designed for coping with the collective-dephasing noise and the collective-rotation noise, respectively. In 2011, Wang et al. presented the first QSDC which exploited the hyperentangled state as the information carrier and several QSDC schemes based on the spatial degree of freedom (DOF) of photon, single-photon multi-DOF state and hyperentanglement were proposed subsequently. In addition to the point-to-point QSDC schemes, we also review the QSDC networks. Finally, a perspective of QSDC research is given in the last section. ©, 2015, Chinese Physical Society. All right reserved.

Ren Y.R.,Chongqing University
Zhong yao cai = Zhongyaocai = Journal of Chinese medicinal materials | Year: 2012

To explore the antitumor activities of galactosylated artemisinin in vitro and the related mechanisms. Apoptosis rate of Hela cell was evaluated by using flow cytometry (FCM) analysis. The activity of Caspase-3 was examined by colorimetry. The expression level of p53, BAX, Caspase-3 and BCL-2 was determined by Western blotting. The FCM data showed that galactosylated artemisinin induced apoptosis of Hela cell. The activity and expression level of Caspase-3 were significantly increased when treated with galactosylated artemisinin for 36 h and 72 h. The expression of BAX was also increased markedly, while BCL-2 was reduced after treatment with the drug. However, galactosylated artemisinin had no effects on the expression of p53. Galactosylated artemisinin exhibits great antitumor activities, which may be ralated to triggering cytochrome C apoptotic pathway which mediated by BCL-2 family.

Meng F.,Chongqing University
Chongqing Daxue Xuebao/Journal of Chongqing University | Year: 2013

Three-dimensional liquid-solid coupling finite element analysis for thermo-elasto-hydrodynamic performances for a water-lubricated bearing system is conducted using finite element code, based on the influence coefficient method, and nonlinear optimization method. Meanwhile, the code is validated. Numerical results show that significant elastic deformation and thermal deformation, contact pressure with certain amplitude, and large temperature rise over the range of the small film thickness-roughness ratio can occur for the bearing. Therefore, the above deformation and temperature rise should be considered in designs and applications of water-lubricated bearings.

Zhang Y.,Chongqing University | Liu Q.,Luoyang Normal University | Shi T.,CAS Wuhan Institute of Physics and Mathematics
Journal of Physics B: Atomic, Molecular and Optical Physics | Year: 2012

An accurate one-centre method is here applied to the calculation of the equilibrium distances and the energies for the hydrogen molecular ion in magnetic fields ranging from 10 9G to 4.414 × 10 13 G. Both the radial and angular wavefunctions were expanded in terms of optimization B-splines. The slow convergence problem in the general one-centre method and singularities at the nuclear positions of the H + 2 were solved well. The accuracy of the one-centre method has been improved in this way. We compared our results with those generated by high-precision methods from published studies. Equilibrium distances of the 1σ g,u, 1π g,u, 1δ g,u and 2σ g states of the H + 2 in strong magnetic fields were found to be accurate to three to four significant digits at least up to 2.35 × 10 12 G, even for the antibonding states 1σ u, 1π g and 1δ u, whose equilibrium distances R eq are very large. © 2012 IOP Publishing Ltd.

Zheng S.,Chongqing University
Nuclear Physics B | Year: 2012

Supersymmetric models based on the scenario of gauge mediation often suffer from the well-known μ problem. In this paper, we reconsider this problem in low-scale gauge mediation in terms of effective field theory analysis. In this paradigm, all high energy input soft mass can be expressed via loop expansions. If the corrections coming from messenger thresholds are small, as we assume in this letter, then all RG evaluations can be taken as linearly approximation for low-scale supersymmetric breaking. Due to these observations, the parameter space can be systematically classified and studied after constraints coming from electro-weak symmetry breaking are imposed. We find that some old proposals in the literature are reproduced, and two new classes are uncovered. We refer to a microscopic model, where the specific relations among coefficients in one of the new classes are well motivated. Also, we discuss some primary phenomenologies. © 2011.

Zhao L.-J.,Chongqing University
JAMS Journal of Acupuncture and Meridian Studies | Year: 2015

The acupuncture meridian system (AMS) is the key concept of Traditional Chinese Medical Science (TCMS). It is a natural network formed by the tissue space that connects human viscera and skin. In this article, a new hypothesis that the AMS is an auxiliary respiratory system is presented. The AMS collects the CO2 that is produced by tissue supersession and that cannot be excreted via blood circulation, and discharges the CO2 through the body's pores, thus preventing a pressure increase in the internal environment. Thus, local blood circulation will not be blocked, and the body will remain healthy. In addition to neuroregulation and humoral regulation, AMS regulation is an important method of physiological regulation. Furthermore, the pathological principle of the AMS, therapies of TCMS, and the excellent future of the AMS are discussed. © 2015, Medical Association of Pharmacopuncture Institute.

Miranda O.R.,University of Massachusetts Amherst | Chen H.-T.,University of Massachusetts Amherst | You C.-C.,University of Massachusetts Amherst | Mortenson D.E.,University of Massachusetts Amherst | And 3 more authors.
Journal of the American Chemical Society | Year: 2010

We have developed an enzyme-nanoparticle sensor array where the sensitivity is amplified through enzymatic catalysis. In this approach cationic gold nanoparticles are electrostatically bound to an enzyme (β-galactosidase, β-Gal), inhibiting enzyme activity. Analyte proteins release the β-Gal, restoring activity and providing an amplified readout of the binding event. Using this strategy we have been able to identify proteins in buffer at a concentration of 1 nM, substantially lower than current strategies for array-based protein sensing. Moreover, we have obtained identical sensitivity in studies where the proteins are spiked into the complex protein matrix provided by desalted human urine (∼1.5 μM total protein; spiked protein concentrations were 0.067% of the overall protein concentration), demonstrating the potential of the method for diagnostic applications. © 2010 American Chemical Society.

Wan J.,Huazhong University of Science and Technology | Fan A.,Huazhong University of Science and Technology | Liu Y.,Huazhong University of Science and Technology | Yao H.,Huazhong University of Science and Technology | And 3 more authors.
Combustion and Flame | Year: 2015

Behaviors of premixed CH4/air flame in mesoscale channels with and without cavities were experimentally investigated. No stable symmetric flame was observed in the channel without cavities and flame is prone to inclining and pulsating. In contrast, flame can be effectively anchored in the presence of cavities. When the inlet velocity is increased sufficiently high, curved fluctuating flame front appears. Blow-off limits of the channel with cavities are several times larger than the corresponding burning velocity of incoming CH4/air mixture, while the flashback limits are almost the same as the straight channel counterparts. These indicate that the cavities have a strong ability to extend the operational range of inlet velocity. Numerical simulation demonstrates that combined effects, i.e., the formation of recirculation zone and low velocity zone in the cavities, preferential diffusion effect, as well as the preheating effect of upstream inner walls, are major mechanisms responsible for flame stabilization. Furthermore, numerical result reveals that large strain rate and heat loss rate exist at the transition point between the ramped cavity wall and the downstream inner wall, which results in flame splitting at high inlet velocity due to local extinction, and eventually leads to flame blow-off. In summary, the combustion behaviors in the mesoscale channel with cavities strongly depend on the interactions between the reaction zone, conjugate heat exchange and flow field. © 2014 The Combustion Institute.

Chen G.,Chongqing University | Lewis F.L.,University of Texas at Arlington
IEEE Transactions on Systems, Man, and Cybernetics, Part B: Cybernetics | Year: 2011

This paper investigates the cooperative tracking control problem for a group of Lagrangian vehicle systems with directed communication graph topology. All the vehicles can have different dynamics. A design method for a distributed adaptive protocol is given which guarantees that all the networked systems synchronize to the motion of a target system. The dynamics of the networked systems, as well as the target system, are all assumed unknown. A neural network (NN) is used at each node to approximate the distributed dynamics. The resulting protocol consists of a simple decentralized proportional-plus- derivative term and a nonlinear term with distributed adaptive tuning laws at each node. The case with nonconstant NN approximation error is considered. There, a robust term is added to suppress the external disturbances and the approximation errors of the NNs. Simulation examples are included to demonstrate the effectiveness of the proposed algorithms. © 2010 IEEE.

Xu K.,University of Electronic Science and Technology of China | Liu H.,Chongqing University | Zhang Z.,Sichuan Solid State Circuit Research Institute SISC
Applied Optics | Year: 2015

In this paper, we discuss the emission of visible light by a monolithically integrated silicon gate-controlled diode with the p-n junction reverse-biased. Since the MOS-like diode utilizes the field effect to modulate the optical output, the modulation speed will benefit from this mechanism. Hence, a silicon gate-controlled diode structure for optical modulation analyzed its modulation principle, its dynamic characteristics are presented, and the bandwidth of the device is considered to approach GHz in theory due to the field-induced emission mechanism. The prototype MOS-like diode opens up the design of multiterminal silicon light emitting devices (LEDs), where gate electrodes with more than one gate contact overlap several junctions with different junction intersection geometries. The device appears as a good candidate for optical modulation within silicon technology. © 2015 Optical Society of America.

Hui L.,Chongqing University
Advances in Information Sciences and Service Sciences | Year: 2012

As the air cooled technology further increased local content, 1000MW air cooled structure has been placed on our agenda. By contrast, 1000MW air cooled support structure is higher and more complicated. It is significant to study mechanical behaviors on the steel-concrete hybrid structure in order to independently design these structures and further develop the water-efficient technology in China. The structure can meet its stiffness and strengthen needs under the influence of loads. Some member sections can be adjusted in order to optimize the structure design.

Wei S.S.,Chongqing University
Zhongguo ying yong sheng li xue za zhi = Zhongguo yingyong shenglixue zazhi = Chinese journal of applied physiology | Year: 2013

To evaluate the role of serum tumor necrosis factor-alpha (TNF-alpha) and adiponectin on insulin resistance in different fat diet rats. Thirty weanling female rats were randomly divided into 3 group (n = 10): a low-fat soybean oil (LFS; 22% of total energy fed as fat), high-fat soybean oil (HFS; 40% of total energy fed as fat), or high-fat soybean oil and swimming training at the same time (HFS + T). After fed for 10 weeks, the level of TNF-alpha, adiponectin in serum of rats were observed. (1) The body weight, percentage of body fat of HFS group increased compared with that of LFS group (P < 0.05), however those of HFS + T group were decreased (P < 0.05). (2) The level of serum insulin and ISI in HFS group were increased by LFS group (P < 0.05), in HFS+ T group the levels decreased. (3) And the serum level of TNF-alpha and IL-6 in HFS group were higher than those in LFS group (P < 0.05), the serum levels of adiponectin in HFS group were lower than those in LFS rats, and in HFS+ T group the levels of TNF-alpha and IL-6 were lower than those in HFS group (P < 0.05), the adiponectin level was higher than that in HFS group, and there were no significant difference between LFS group and HFS + T group. Exercises training could improve sugar and fat metabolism disorders, which also contributes to improving insulin resistance caused by high-fat diet.

Zhou X.,Shanghai SHR Electrical Power Technology Co. | Zhou X.,Chongqing University
Dianli Zidonghua Shebei/Electric Power Automation Equipment | Year: 2010

Smart substation is divided into system layer and equipment layer. System layer equals to the station level of digital substation. Equipment layer is composed of HV equipment, intelligent component and IED, equaling to the bay layer and process level of digital substation. Intelligent component results from the merging of the primary and secondary equipments. As a part of the intelligent component, protection and measuring-control devices are oriented to the bay. IED is modeled based on IEC61850. Modularization concept, object-oriented technology and PLC technology are used in device program design. The reliability of network communication is ensured by reliable network topology and redundancy technology. Device modeling, FB(Function Block) and LN(Logical Node) design, networks and key technologies, config tools and config steps, virtual terminal, and test method are introduced.

Yu P.,Chongqing Normal University | Guo S.F.,Southwest University | Wang J.F.,Chongqing University
Materials and Design | Year: 2012

The structural evolution and mechanical properties of a Zr-based bulk metallic glass during superplastic gas pressure forming were investigated by differential scanning calorimetry (DSC), transmission electron microscopy (TEM) and nanoindentation measurements at the optimum temperature of 676. K under different stress states. It was found that the crystallized volume fraction of the deformed specimens with die aspect ratios of 1:1 and 3:2 are estimated to be 15% and 25%, respectively. The high resolution TEM results show that more particles at the nanometer level exist in the deformed specimen with the aspect ratio of 3:2. The nanoindentation tests further illustrate that the Young's modulus and hardness of the deformed specimens have increased, and the deformed sample with the aspect of 1:1 shows slightly smaller modulus and hardness. The nano-scale crystalline structure induced by gas pressure forming process is considered to be the main reason for the change of the mechanical properties, and in addition to thermal and strain energy. In addition, the structural evolution is also affected by the stress state in the process of gas pressure forming. © 2012 Elsevier Ltd.

Xin R.,Chongqing University | Ren F.,Hong Kong University of Science and Technology | Leng Y.,Hong Kong University of Science and Technology
Materials and Design | Year: 2010

This study aims to prepare the biologically important hydroxyapatite (HA), dicalcium phosphate dihydrate (DCPD) and dicalcium phosphate anhydrous (DCPA) phases in simple EDTA - assisted hydrothermal method. X-ray diffraction results showed that pure DCPD, DCPA and HA nano-crystals were obtained in the Ca-EDTA/PO4 solutions at 120 °C, 180 °C and 210 °C, respectively. Thermal gravimetric analysis of the DCPD precipitates revealed that phase transformations of DCPD to DCPA and DCPA to HA occurred at 139 °C and 195 °C, respectively, which resulted in the different Ca-P phases during hydrothermal synthesis at different temperature ranges. © 2009 Elsevier Ltd. All rights reserved.

Zhao H.,Chongqing University
Journal of Superconductivity and Novel Magnetism | Year: 2010

A general formula of the long-range correlation energy E c for the π electron systems is given, which includes diagonal interactions and off-diagonal interactions and we put forward to a correlation Hamiltonian at the first time. It is found that the effects of the off-diagonal interactions W and X on the correlation energies are opposite. The effect of W is to increase the correlation energies, but the effect of X is being counteracted by the integral term J due to |X| ∼ |J|. The long-range correlation energies decrease with increasing the screening effect. At normal screening, the influence of W on the correlation energies can be neglected. © 2010 Springer Science+Business Media, LLC.

Raval C.M.,University of Bath | Zhong J.L.,Chongqing University | Mitchell S.A.,University of Bath | Tyrrell R.M.,University of Bath
Free Radical Biology and Medicine | Year: 2012

Up-regulation of heme oxygenase 1 (HO-1) by ultraviolet A (UVA; 320-380 nm) irradiation of human skin cells protects them against oxidative stress. The role of Nrf2 in up-regulation of HO-1 and other phase II genes is well established. The mechanism underlying Bach1-mediated HO-1 repression is less well understood although cellular localization seems to be crucial. Because prolonged HO-1 overexpression is likely to be detrimental, it is crucial that activation of the gene is transient. We now show that UVA irradiation of cultured human skin fibroblasts enhances accumulation of Bach1 mRNA and protein severalfold. Endogenous Bach1 protein accumulates in the nucleus after 8 h and may occupy MARE sites after HO-1 activation thus providing a compensatory mechanism to control HO-1 overexpression. Overexpression of Bach1, together with MafK, represses basal and UVA-mediated HO-1 protein expression, whereas silencing of the Bach1 gene by Bach1-specific siRNAs causes robust enhancement of constitutive HO-1 levels. UVA treatment of cells in which Bach1 has been silenced leads to higher levels of induction of the HO-1 protein. Although Bach1 protein is exported from the nucleus 12 h after UVA irradiation, the release of free cellular heme from microsomal heme-containing proteins is immediate rather than delayed. Although heme does promote the export of Bach1 via the Crm1/exportin 1 pathway and is involved in the delayed UVA-mediated export of the protein, it is not clear how this occurs. © 2011 Elsevier Inc.

Guo C.-Z.,Chongqing University of Arts and Sciences | Liao W.-L.,Chongqing University of Arts and Sciences | Chen C.-G.,Chongqing University of Arts and Sciences | Chen C.-G.,Chongqing University
Journal of Power Sources | Year: 2014

The development of less expensive, more active, and more stable catalyst substitute for Pt/C catalysts for oxygen reduction has recently become a hot topic. In this paper, we report a new strategy to design nitrogen-doped non-precious metal catalysts via the copyrolysis of metallic iron, soybean biomass, and carbon support at high temperatures. The results show that the nitrogen in electrocatalysts is mainly in the form of pyridinic and pyrrolic N species. The metallic Fe in the precursor can facilitate the transformation of quaternary N with a three-dimensional structure to planar pyridinic and pyrrolic N inside carbon matrix during pyrolysis, thereby improving the electrocatalytic activity of the prepared catalysts. We suggest that the planar N species may be the catalytically active center structures and may contribute to the enhancement of oxygen reduction reaction performance in an alkaline electrolyte. The prepared catalyst has superior tolerance against methanol crossover effect and outstanding stability compared with commercial Pt/C catalysts. © 2014 Elsevier B.V. All rights reserved.

Deng M.,Chongqing University | Xiang Y.,East China University of Science and Technology
Ultrasonics | Year: 2015

Abstract The effect of second-harmonic generation (SHG) by primary ultrasonic guided wave propagation is analyzed, where the nonlinear elastic, piezoelectric, and dielectric properties of the piezoelectric plate material are considered simultaneously. The formal solution of the corresponding second-harmonic displacement field is presented. Theoretical and numerical investigations clearly show that the SHG effect of primary guided wave propagation is highly sensitive to the electrical boundary conditions of the piezoelectric plate. The results obtained may provide a means through which the SHG efficiency of ultrasonic guided wave propagation can effectively be regulated by changing the electrical boundary conditions of the piezoelectric plate. © 2015 Elsevier B.V.

Wang S.,Chongqing University
Philosophical Magazine | Year: 2015

A fundamental equation is derived for the structure of dislocations in solids. With the interaction potential that can be obtained properly from the first principle, the equation provides a complete basis for a comprehensive study of the dislocation structure. In particular, the full structural feature and related properties of dislocation can be predicted theoretically, which makes it possible to compare precisely the theoretical results and what is produced by experiments or numerical simulations. © 2015 Taylor & Francis.

Sun Y.,University of Texas at Tyler | Sun Y.,Pennsylvania State University | Sundell J.,Tsinghua University | Sundell J.,Chongqing University
Science of the Total Environment | Year: 2011

A high prevalence and racial disparities in asthma and allergy have been observed in American children. This study aimed to identify risk factors for asthma and allergy among children, and their contribution to racial disparities in allergy prevalence. A population-based cross-sectional study was carried out among children aged 1-8. years in Northeast Texas 2008-2009. The health conditions, life style and home environment of 3766 children were surveyed by parental questionnaires through e.g. daycares, elementary school, and medical clinics. Among participants who indicated their ethnicity, 255 were Mexican-Americans, 178 Afro-Americans and 969 Caucasians. Afro-American children had a significantly higher prevalence of asthma and eczema. Caucasian had the highest prevalence of rhinitis. Compared to Mexican-American children, Afro-American and Caucasian children were breast fed shorter time, more often went to day care center, had pets and environmental tobacco smoke exposure at home more often. For all children, being at a day care center, being exposed to dampness and environmental tobacco smoke at home were strong risk factors for asthma and allergy. Central air conditioning system was associated with an increased prevalence of wheeze among Mexican-American children, while pets were associated with an increased risk of rhinitis among Afro-American and Caucasian children. Caucasian children were generally not healthier than relatively poor Mexican-American children. Differences in the prevalence of asthma and allergy between races cannot be explained by socioeconomic status only. Life style and home environmental exposures are important risk factors for asthma and allergy in Northeast Texas children. © 2011 Elsevier B.V.

Yu M.,Key Laboratory for Optoelectronic Technology and Systems | Wang S.,Chongqing University
Smart Materials and Structures | Year: 2010

A new composite magnetorheological elastomer (MRE) embedded with a copper coil was designed to induce a magnetic field inside and improve the field-dependent properties of the MRE. The composite MRE can avoid flux leakage, increase the utilization ratio of the magnetic field, and make magnetorheological equipment lightweight. A shearing stress-strain experiment for the composite MRE was carried out and the result showed that the composite MRE has a good magnetorheological effect. © 2010 IOP Publishing Ltd.