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Runge T.,University of Wisconsin - Madison | Zhang C.,University of Wisconsin - Madison | Zhang C.,South China University of Technology
Industrial and Engineering Chemistry Research | Year: 2012

In this paper, we report on a two-stage acid-catalytic conversion of carbohydrates from hybrid poplar wood chips into levulinic acid (LA), a renewable platform chemical which can be used for fuels and chemicals. It was hypothesized that under the harsh acid conditions utilized during LA production, the pentose fraction in biomass would first form furfurals which would then polymerize with saccharides forming humins. These reactions would both reduce any potential value from the pentose fraction as well as lower the levulinic acid yield. To test this idea, a two-stage conversion process was designed starting with a mild acid extraction to remove the majority of the pentoses while maintaining the hexose sugars in a solid form utilizing previously described optimized conditions. LA was then produced by subjecting the extracted solids to a second more severe step. The temperature, time, acid concentration, and a liquor-to-wood ratio were varied and modeled to find the optimal conditions. The best conditions were high acid concentration, high temperature, and low substrate consistency, which produced a maximum molar yield of 66% based on the hexose content or 17.5 wt % based of the initial biomass. A comparison of this two-stage process to a single-stage process without the pentose extraction was performed both with biomass and model compounds, which indicated no pentose or furfural in the product stream and a marked molar yield decrease in LA yield from the presence of pentose sugars, validating our initial hypothesis. © 2012 American Chemical Society.

Zhang F.,General Hospital of Guangzhou Military Command | Zhang F.,South China University of Technology | Jiang L.,General Hospital of Guangzhou Military Command
Neuropsychiatric Disease and Treatment | Year: 2015

Amyloid-β plaques and neurofibrillary tangles are the main neuropathological hallmarks in Alzheimer’s disease (AD), the most common cause of dementia in the elderly. However, it has become increasingly apparent that neuroinflammation plays a significant role in the pathophysiology of AD. This review summarizes the current status of neuroinflammation research related to AD, focusing on the connections between neuroinflammation and some inflammation factors in AD. Among these connections, we discuss the dysfunctional blood–brain barrier and alterations in the functional responses of microglia and astrocytes in this process. In addition, we summarize and discuss the role of intracellular signaling pathways involved in inflammatory responses in astrocytes and microglia, including the mitogen-activated protein kinase pathways, nuclear factor-kappa B cascade, and peroxisome proliferator–activated receptor-gamma transcription factors. Finally, the dysregulation of the control and release of pro- and anti-inflammatory cytokines and classic AD pathology (amyloid plaques and neurofibrillary tangles) in AD is also reviewed. © 2015 Zhang and Jiang.

Hong B.,South China University of Technology | Shen J.,Virginia Institute of Marine Science
Journal of Geophysical Research: Oceans | Year: 2013

Dissolved oxygen (DO) replenishment in the bottom waters of an estuary depends on physical processes that are significantly influenced by external forcings. The vertical exchange time (VET) is introduced in this study to quantify the physical processes that regulate the DO replenishment in the Chesapeake Bay. A 3-D numerical model was applied to simulate the circulation, VET, and DO. Results indicate that VET is a suitable parameter for evaluating the bottom DO condition over both seasonal and interannual timescales. The VET is negatively correlated with the bottom DO. Hypoxia (DO <2 mg L -1) will develop in the Bay when VET is greater than 23 days in summer if mean total DO consumption rate is about 0.3 g O2 m -3 d-1. This critical VET value may vary around 23 days when the total DO consumption rate changes. The VET volume (volume of water mass with VET >23 days) can account for 77% of variations of hypoxic volume in the main Bay. The VET cannot explain all the DO variations as it can only account for the contribution of physical processes that regulate DO replenishment. It is found that the short-term vertical exchange process is highly controlled by the wind forcing. The VET volume decreases when the high-speed wind events are frequent. The summertime VET volume is less sensitive to short-term variations (pulses) of river discharge. It is sensitive to the total amount of river discharge and the high VET volume can be expected in the wet year. Key Points Vertical transport time is used to quantify bottom DO replenishment processes Majority variations of bottom DO can be interpreted by vertical transport time Interannual variations of hypoxic volume and VTT volume are correlated. ©2013. American Geophysical Union. All Rights Reserved.

Wang X.,South China University of Technology
Zhongguo Dianji Gongcheng Xuebao/Proceedings of the Chinese Society of Electrical Engineering | Year: 2014

The third generation of wide bandgap semiconductor as silicon carbide (SiC) breakthroughs the performance caps of silicon (Si) based power semiconductor devices in voltage, temperature, switching loss and switching speed, thus, the weight, size and cost of power electronic converters may be decreased, and the performance of power electronic system may be improved significantly. Power driver of electric vehicles with high power density is always the main development challenge of high power electric vehicles. The usage of wide bandgap semiconductors may has significant impacts on new generation electric vehicles, especially hybrid electric vehicles. In this paper, the development of SiC power devices is introduced first; then, research statues and application prospects of SiC devices in electric vehicle are presented; last, the main problems of EV driving system using SiC power devices are discussed. © 2014 Chin. Soc. for Elec. Eng.

Liu X.,South China University of Technology
Journal of Network and Computer Applications | Year: 2016

Energy hole is an inherent problem, which leads to significant network lifetime reduction and much energy waste in wireless sensor networks (WSNs). To avoid energy holes, full consideration of energy consumption minimization (ECM) and energy consumption balancing (ECB) is badly needed. In this paper, we propose a novel transmission range adjustment strategy, in which ECM and ECB are jointly considered and fully reflected, to realize the objectives of energy hole avoiding and network lifespan prolonging for WSNs. Firstly, we propose a short-trip moving scheme in ant colony optimization (ACO), which can decrease algorithm complexity and improve convergence speed. Secondly, we present a concept of reference transmission distance (RTD) which helps to realize local ECM and ECB. Thirdly, we present a concept of energy per node (EPN) which is used to achieve global ECM and ECB. Finally, simulations are used to validate the effectiveness and superiority of our findings. © 2016 Elsevier Ltd. All rights reserved.

Fu X.,University of Arkansas | Fu X.,South China University of Technology | Naumov I.I.,University of Arkansas | Naumov I.I.,Carnegie Institution of Washington | Fu H.,University of Arkansas
Nano Letters | Year: 2013

Dipole collective behavior and phase transition in ferroelectric (FE) Pb(Zr0.5Ti0.5)O3 nanowires, caused by modulated electric fields, are reported. Our result also leads to the finding of a rather outstanding electromechanical d31 response in a 8.4 nm diameter PZT wire, which may potentially outperform bulk PMN-PT and PZN-PT. Moreover, we further demonstrate the existence of a new type of morphotropic phase boundary (MPB) that bridges two dissimilar structure phases of different order parameters. Microscopic insights for understanding the collective behavior and the structural phase within the new MPB are provided. © 2012 American Chemical Society.

Li M.,South China University of Technology
Scientometrics | Year: 2015

In terms of technology evolution pathways, patents, articles and projects are the traditional analytical dimensions, particularly patent analysis. Analysis results based on traditional dimensions are used to present the evolutionary stage based on the theory of the technology life cycle (TLC). However, traditional TLC is insufficient to explain the inner driving force of technology evolution; instead, it just describes the process. Promoting ideality degree, one of evolutionary principles in the framework of Teoriya Resheniya Izobreatatelskikh Zadatch, is combined with patent and article analysis, and then a novel three-dimensional analytical method is introduced. In a case study with one curial material and novel technology, graphene attracted the attention of all types of organizations, but the development prospects of the graphene industry are not clear, and its potential abilities and applications should be deeply explored. © 2015 Akadémiai Kiadó, Budapest, Hungary

Ye F.,South China University of Technology
Expert Systems with Applications | Year: 2010

How to select suitable partners is critical to virtual enterprise (VE) success and has attracted much attention for both researchers and practitioners. In many practical situations, there usually exists incomplete and uncertain information, and the decision makers cannot easily express their judgments on the candidates with exact and crisp values. Therefore, an extended technique for order preference by similarity to ideal solution (TOPSIS) method for group decision making with interval-valued intuitionistic fuzzy numbers is proposed to solve the partner selection problem under incomplete and uncertain information environment in this paper. And the feasibility and practicability of the extended TOPSIS method are further manifested through an illustrative example. Results show that this extended TOPSIS method for group decision making with interval-valued intuitionistic fuzzy numbers is more suitable to cope with the partner selection problem under incomplete and uncertain information environment. © 2010 Elsevier Ltd. All rights reserved.

Wu S.,City University of Hong Kong | Wong H.-S.,City University of Hong Kong | Yu Z.,South China University of Technology
IEEE Transactions on Circuits and Systems for Video Technology | Year: 2014

People naturally escape from a place when unexpected events happen. Based on this observation, efficient detection of crowd escape behavior in surveillance videos is a promising way to perform timely detection of anomalous situations. In this paper, we propose a Bayesian framework for escape detection by directly modeling crowd motion in both the presence and absence of escape events. Specifically, we introduce the concepts of potential destinations and divergent centers to characterize crowd motion in the above two cases respectively, and construct the corresponding class-conditional probability density functions of optical flow. Escape detection is finally performed based on the proposed Bayesian framework. Although only data associated with nonescape behavior are included in the training set, the density functions associated with the case of escape can also be adaptively updated using observed data. In addition, the identified divergent centers indicate possible locations at which the unexpected events occur. The performance of our proposed method is validated in a number of experiments on crowd escape detection in various scenarios. © 2013 IEEE.

Wang X.-T.,South China University of Technology
Physica A: Statistical Mechanics and its Applications | Year: 2010

This paper deals with the problem of discrete time option pricing using the multifractional Black-Scholes model with transaction costs. Using a mean self-financing delta hedging argument in a discrete time setting, a European call option pricing formula is obtained. The minimal price of an option under transaction costs is obtained. In addition, we show that scaling and long range dependence have a significant impact on option pricing. © 2009 Elsevier B.V. All rights reserved.

Huo B.,Zhejiang University | Zhao X.,China Europe International Business School | Zhao X.,South China University of Technology | Zhou H.,University of New Hampshire
Production and Operations Management | Year: 2014

Information sharing in supply chains has become an important topic over the past decade. This study uses data from 617 Chinese manufacturing firms to investigate the relationships among competitive environments, supply chain information sharing (SCIS), and supply chain performance. The results of structural equation modeling analysis show that (i) international competition is positively related to all three types of SCIS whereas local competition is not significantly related to any of the three types, (ii) internal information sharing is positively related to external information sharing with suppliers and customers, and (iii) internal information sharing and information sharing with customers are positively related to superior supply chain performance, whereas supplier information sharing is not significantly related to performance. The findings enhance our understanding of the relationships among competitive environment, SCIS, and supply chain performance in Chinese manufacturing settings. © 2013 Production and Operations Management Society.

Cheng W.-C.,Chinese Culture University | Li B.,South China University of Technology
Journal of Statistical Physics | Year: 2010

This paper introduces the notion of entropy dimension to measure the complexity of zero entropy dynamical systems, including the probabilistic and the topological versions. These notions are isomorphism invariants for measure-preserving transformation and continuity. We discuss basic propositions for entropy dimension and construct some examples to show that the topological entropy dimension attains any value between 0 and 1. This paper also gives a symbolic subspace to achieve zero topological entropy, but with full entropy dimension. © 2010 Springer Science+Business Media, LLC.

Bo X.,South China University of Technology
Physica A: Statistical Mechanics and its Applications | Year: 2010

Prevailing models of the evolutionary prisoner's game on networks always assume that agents are pursuing their own profit maximization. But the results from experimental games show that many agents have other-regarding preference. In this paper, we study the emergence of cooperation from the prisoner's dilemma game on complex networks while some agents exhibit other-regarding preference such as inequality aversion, envious and guilty emotions. Contrary to common ideas, the simulation results show that the existence of inequality aversion agents does not promote cooperation emergence on a BA (Barabási and Albert) scale-free network in most situations. If the defection attraction is big and agents exhibit strong preference for inequality aversion, the frequency of cooperators will be lower than in situations where no inequality aversion agents exist. In some cases, the existence of the inequality agents will even induce the frequency of cooperators to zero, a feature which is not observed in previous research on the prisoner's dilemma game when the underlying interaction topology is a BA scale-free network. This means that if an agent cares about equality too much, it will be difficult for cooperation to emerge and the frequency of cooperators will be low on BA networks. The research on the effect of envy or guilty emotions on the emergence of cooperation in the prisoner's dilemma game on BA networks obtains similar results, though some differences exist. However, simulation results on a WS (Watts and Strogatz) small-world network display another scenario. If agents care about the inequality of agents very much, the WS network favors cooperation emergence in the prisoners' dilemma game when other-regarding agents exist. If the agent weight on other-regarding is lowered, the cooperation frequencies emerging on a WS network are not much different from those in situations without other-regarding agents, although the frequency of cooperators is lower than those of the situation without other-regarding preference agents sometimes. All the simulation results imply that inequality aversion and its variations can have important effects on cooperation emergence in the prisoner's dilemma game, and different network topologies have different effects on cooperation emergence in the prisoner's dilemma game played on complex networks. © 2009 Elsevier B.V. All rights reserved.

Xie W.,South China University of Technology
Journal of the Franklin Institute | Year: 2010

A new feedback controller architecture based on disturbance observer (DOB) is proposed to deal with high-frequency measurement noise for high accuracy performance. Compared with the classical DOB-based control system the proposed control structure adds another controller to compensate the feedback of system output. Thus, these influences of both high-frequency measurement noise and low-frequency external disturbance on the system output could be eliminated simultaneously. Meanwhile, the new control system architecture can potentially overcome the conflict between performance and robustness in the traditional feedback framework. A numerical example is included at the end of this paper to illustrate the effectiveness. © 2010 The Franklin Institute. Published by Elsevier Ltd. All rights reserved.

Xue S.,Jilin University | Yao L.,Jilin University | Shen F.,Jilin University | Gu C.,Jilin University | And 2 more authors.
Advanced Functional Materials | Year: 2012

Highly efficient and fully solution-processed white organic light-emitting diodes (WOLEDs) based on fluorescent small molecules and a polar conjugated polymer as electron-injection material are reported. The emitting layer in the WOLEDs is a blend of new blue-, green-, and red-fluorescent small molecules, with a blending ratio of 100:0.4:0.8 (B/G/R) by weight, and a methanol/water soluble conjugated polymerpoly[(9,9-bis(30-(N,N-dimethylamino)propyl)-2,7- fluorene)-alt-2,7-(9,9-dioctylfluorene)] (PFN) acts as the electron-injection layer (EIL). All the organic layers are spin-coated from solution. The device exhibits pure white emission with a maximum luminous efficiency of 9.2 cd A -1 and Commission Internationale d'Eclairage Coordinates of (0.35, 0.36). PFN acting as the EIL material plays a key role in the improvement of the device performance when used in solution-processed small-molecule WOLEDs. © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Ma H.,South China University of Technology
International Journal for Numerical Methods in Biomedical Engineering | Year: 2010

Although exact solutions for linear static analysis of most frame structures can be obtained by the finite element method, it is very difficult to get exact solutions for free vibration and harmonic analyses for nontrivial cases. This paper extends an earlier study on exact solutions of axial vibration problems of elastic bars to dynamic analyses of elastic frame structures. New shape functions for the transverse displacement field are constructed by using the homogeneous governing equations and then a novel beam element is formulated. Combining the new (bending) beam element and the one developed earlier for elastic bars yields a new element for general frame structures. The new frame element can be used to get exact solutions for both natural frequency and undamped harmonic analyses of frame structures. Illustrative examples are presented to demonstrate the effectiveness of the new element and the algorithm. Copyright © 2008 John Wiley & Sons, Ltd.

Wang X.-T.,South China University of Technology
Physica A: Statistical Mechanics and its Applications | Year: 2010

This paper deals with the problem of discrete time option pricing by the fractional Black-Scholes model with transaction costs. By a mean self-financing delta-hedging argument in a discrete time setting, a European call option pricing formula is obtained. The minimal price Cmin (t, St) of an option under transaction costs is obtained as timestep δ t = (frac(2, π))frac(1, 2 H) (frac(k, σ))frac(1, H), which can be used as the actual price of an option. In fact, Cmin (t, St) is an adjustment to the volatility in the Black-Scholes formula by using the modified volatility σ sqrt(2) (frac(2, π))frac(1, 2) - frac(1, 4 H) (frac(k, σ))1 - frac(1, 2 H) to replace the volatility σ, where frac(k, σ) < (frac(π, 2))frac(1, 2), H > frac(1, 2) is the Hurst exponent, and k is a proportional transaction cost parameter. In addition, we also show that timestep and long-range dependence have a significant impact on option pricing. © 2009 Elsevier B.V. All rights reserved.

A fractional order sliding mode control (FROSMC) scheme based on parameters auto-tuning for the velocity control of permanent magnet synchronous motor (PMSM) is proposed in this paper. The control law of the proposed F(R)OSMC scheme is designed according to Lyapunov stability theorem. Based on the property of transferring energy with adjustable type in F(R)OSMC, this paper analyzes the chattering phenomenon in classic sliding mode control (SMC) is attenuated with F(R)OSMC system. A fuzzy logic inference scheme (FLIS) is utilized to obtain the gain of switching control. Simulations and experiments demonstrate that the proposed FROSMC not only achieve better control performance with smaller chatting than that with integer order sliding mode control, but also is robust to external load disturbance and parameter variations. Copyright © 2012 ISA. Published by Elsevier Ltd. All rights reserved.

Xie W.,South China University of Technology
Asian Journal of Control | Year: 2012

This paper provides a kind of new matrix inequalities formulation for multi-objective H2/L2 performance controller synthesis of linear parameter varying systems. These new matrix inequalities enable us to parameterize controllers without involving the Lyapunov variables in the formulation. Taking advantage of this feature, we can readily design multiobjective controllers with non-common parameter-dependent Lyapunov variables and two adjustable scalars. Furthermore, to obtain possibly lower values of performance criteria, a linear matrix inequalities (LMI)-based optimal problem is solved by using the grid of the space that is combined with these two scalars. Finally, a numerical example is included to illustrate the effectiveness of the proposed method. Copyright © 2011 John Wiley and Sons Asia Pte Ltd and Chinese Automatic Control Society.

Sun Z.,South China University of Technology
Automatica | Year: 2012

In this work, we address the problem of robust switching design, which seeks a switching signal that makes the switched system exponentially stable and robust against switching perturbations. To properly capture the sensitivity of a switching signal undergoing various switching perturbations, we define the relative distance between state-feedback path-wise switching signals. We establish that any stabilizing state-feedback path-wise switching signal is robust with respect to switching perturbations. A lower bound of the robustness margin is explicitly presented. © 2011 Elsevier Ltd. All rights reserved.

Chen J.,CAS Guangzhou Institute of Energy Conversion | Zhao G.,CAS Guangzhou Institute of Energy Conversion | Chen L.,South China University of Technology
RSC Advances | Year: 2014

Direct conversion of fructose into 5-hydroxymethylfurfural (HMF) and alkyl levulinate is achieved by making use of ionic liquid-based polyoxometalate salts (IL-POMs) as solid acid catalysts. Among these solid acids, phosphotungstic acid-derived IL-POM shows the highest catalytic performance in both the HMF and ethyl levulinate (EL) formation. A study for optimizing the reaction conditions such as the reaction time and the temperature has been performed. High HMF and EL yields of up to 99% and 82%, respectively, are obtained from fructose under the investigated conditions. Moreover, the generality of the catalyst is further demonstrated by processing representative di- and polysaccharides such as sucrose and inulin with good yields to HMF (76% from inulin and 48% from sucrose) and EL (67% from inulin and 45% from sucrose), again under mild conditions, thereby eliminating the separate hydrolysis step before the dehydration reaction. The catalyst recycling experiment indicates that the adsorption and accumulation of oligomeric products on the catalyst surface results in a partial deactivation of catalyst. The mechanism research reveals that a major pathway for EL formation involves a fructose-to-HMF transformation followed by HMF etherification and rehydration of HMF-ether to give EL. The research highlights an efficient, environment-friendly and recyclable solid acid for biomass valorization. © 2013 The Royal Society of Chemistry.

Wang X.,Hefei University of Technology | Liu G.,Hefei University of Technology | Zhang G.,South China University of Technology
Langmuir | Year: 2012

We have systematically investigated the effect of surface wettability on ion-specific adsorption of bovine serum albumin (BSA) by using quartz crystal microbalance with dissipation (QCM-D) and surface plasmon resonance (SPR). The changes in frequency (Δf) and resonance unit (ΔRU) show a nonmonotonous change of the adsorbed amount of BSA as a function of molar fraction of 1-dodecanethiol (xDDT) of the self-assembled monolayer at pH 3.8, while the amount of adsorbed protein gradually increases with the xDDT at pH 7.4. The small changes of dissipation (ΔD) indicate that BSA molecules form a quite rigid protein layer on the surfaces, which results in only a slight difference in the adsorbed mass between the mass-uptake estimations from the Sauerbrey equation and the Voigt model. The difference in the adsorbed mass between QCM-D and SPR measurements is attributed to the coupled water in the protein layer. On the other hand, specific anion effect is observed in the BSA adsorption at pH 3.8 with the exception of the surface at xDDT of 0%, but no obvious cation specificity can be observed at pH 7.4. The ΔD-Δf plots show that the BSA adsorption at pH 3.8 has two distinct kinetic processes. The first one dominated by the protein-surface interactions is an anion-nonspecific process, whereas the second one dominated by the protein structural rearrangements is an anion-specific process. At pH 7.4, the second kinetic process can only be observed at the relatively hydrophobic surfaces, and no cation specificity is observed in the first and second kinetic processes. © 2012 American Chemical Society.

Xie Z.,Guangzhou Academy of Energy Testing and Inspection | Ma X.,South China University of Technology
Bioresource Technology | Year: 2013

The thermal characteristics and kinetics of paper sludge, rice straw and their blends were evaluated under combustion condition. The paper sludge was blended with rice straw in the range of 10-95. wt.% to investigate their co-combustion behaviour. There was significant interaction between rice straw and paper sludge in high temperature. The combustion of paper sludge and rice straw could be divided into two stages. The value of the activation energy obtained by the Friedman and the Ozawa-Flynn-Wall (OFW) first decreased and then increased with the conversion degree rising. The average activation energy did not monotonically decrease with increasing the percentage of rice straw in the blends. When the percentage of rice straw in the blends was 80%, the value of the average activation energy was the smallest, which was 139. kJ/mol obtained by OFW and 132. kJ/mol obtained by Friedman, respectively. © 2013 Elsevier Ltd.

Liu Y.P.,South China University of Technology | Reddy J.N.,Texas A&M University
International Journal of Structural Stability and Dynamics | Year: 2011

A nonlocal Timoshenko curved beam model is developed using a modified couple stress theory and Hamilton's principle. The model contains a material length scale parameter that can capture the size effect, unlike the classical Timoshenko beam theory. Both bending and axial deformations are considered, and the Poisson effect is incorporated in the model. The newly developed nonlocal model recovers the classical model when the material length scale parameter and Poisson's ratio are both taken to be zero and the straight beam model when the radius of curvature is set to infinity. In addition, the nonlocal BernoulliEuler curved beam model can be realized when the normal cross-section assumption is restated. To illustrate the new model, the static bending and free vibration problems of a simply supported curved beam are solved by directly applying the formulas derived. The numerical results for the static bending problem reveal that both the deflection and rotation of the simply supported beam predicted by the new model are smaller than those predicted by the classical Timoshenko curved beam model. Also, the differences in both the deflection and rotation predicted by the current and classical Timoshenko model are very large when the beam thickness is small, but they diminish with the increase of the beam height. Similar trends are observed for the free vibration problem, where it is shown that the natural frequency predicted by the nonlocal model is higher than that by the classical model, and the difference between them is significantly large only for very thin beams. These predicted trends of the size effect at the micron scale agree with those observed experimentally. © 2011 World Scientific Publishing Company.

Pan B.,Beihang University | Yu L.,Beihang University | Wu D.,Beihang University | Tang L.,South China University of Technology
Optics and Lasers in Engineering | Year: 2013

Lens distortion practically presents in a real optical imaging system causing non-uniform geometric distortion in the recorded images, and gives rise to additional errors in the displacement and strain results measured by two-dimensional digital image correlation (2D-DIC). In this work, the systematic errors in the displacement and strain results measured by 2D-DIC due to lens distortion are investigated theoretically using the radial lens distortion model and experimentally through easy-to-implement rigid body, in-plane translation tests. Theoretical analysis shows that the displacement and strain errors at an interrogated image point are not only in linear proportion to the distortion coefficient of the camera lens used, but also depend on its distance relative to distortion center and its magnitude of displacement. To eliminate the systematic errors caused by lens distortion, a simple linear least-squares algorithm is proposed to estimate the distortion coefficient from the distorted displacement results of rigid body, in-plane translation tests, which can be used to correct the distorted displacement fields to obtain unbiased displacement and strain fields. Experimental results verify the correctness of the theoretical derivation and the effectiveness of the proposed lens distortion correction method. © 2012 Elsevier Ltd. All rights reserved.

Xie L.,South China University of Technology
International Review on Computers and Software | Year: 2012

The paper proposes an analytic model to evaluate delay for traffic with different priorities in an unsaturated IEEE 802.11e Wireless Local Area Network. By modeling each station as a discrete time G/G/1 queue, we derive expressions of end-to-end delay. Different from other analytic models, which assume that each station has the same traffic load, our model can be used to analyze asymmetry networks where different stations have different priority traffics. Simulation studies show that the proposed model matches well with simulation results. © 2012 Praise Worthy Prize S.r.l. - All rights reserved.

Peng P.,King Abdullah University of Science and Technology | Mei J.,South China University of Technology | Wu Y.,King Abdullah University of Science and Technology
Physical Review B - Condensed Matter and Materials Physics | Year: 2012

We present a lumped model for the rotational modes induced by the rotational motion of individual scatterers in two-dimensional phononic crystals comprised of square arrays of solid cylindrical scatterers in solid hosts. The model provides a physical interpretation of the origin of the rotational modes, reveals the important role played by the rotational motion in determining the band structure, and reproduces the dispersion relations in a certain range. The model increases the possibilities of manipulating wave propagation in phononic crystals. In particular, expressions derived from the model for eigenfrequencies at high symmetry points unambiguously predict the presence of a new type of Dirac-like cone at the Brillouin center, which is found to be the result of accidental degeneracy of the rotational and dipolar modes. © 2012 American Physical Society.

Xie W.,South China University of Technology
IET Control Theory and Applications | Year: 2012

The study deals with the quadratic L2-gain performance linear parameter-varying realisation of parametric transfer functions and state-feedback gain scheduling control. It is shown that any parametric transfer function, which has L2-gain performance with a bound for all constant parameters values, admits a state space realisation guaranteeing quadratic L2-gain performance with the bound under arbitrary parameter variations. A reasonably general procedure is provided to find such a realisation with linear matrix inequality optimal technique. Furthermore, according to the realisation, the state-feedback gain scheduling control design is also dealt with. Finally, a simple numerical example is given to illustrate the efficiency of the proposed method. © 2012 The Institution of Engineering and Technology.

Liang J.Z.,South China University of Technology
Journal of Thermoplastic Composite Materials | Year: 2010

The melt volume flow rate (MVR) is an important parameter for characterization of flow properties of polymer. The MVR of the polypropylene composites filled with diatomite particles was measured by means of a MVR instrument to investigate the effects of the filler content, particle size and extrusion conditions (temperature 210-230°C, load 5.0-12.5 kg) on the melt flow properties of the composite systems. The results showed that the MVR of the composites increased as a quadratic function with the increase of load, while decreased nonlinearly with the increase of filler particle diameter. The MVR was a linear function of temperature. The MVR decreased quickly when the filler volume fraction (θf) was <5%, and then reduced slightly with an increase of θf. In addition, the melt shear flow obeyed roughly power law under the experimental conditions, and the influence of particle size on the temperature sensitivity of the melt shear viscosity is insignificant at low filler concentration. © SAGE Publications 2010.

Wu J.,South China University of Technology
International Journal of Automotive Technology | Year: 2012

This paper presents a robust optimization method to decrease the variations in the performance of the designed system caused by the unavoidable manufacturing, installation or measurement errors of the design variables. Generally, it is difficult and costly to determine statistical information with sufficient precision for uncertain design variables; in this study, interval numbers are used to describe the uncertain design variables, and only the bounds of these variables are required. An improved interval truncation method is presented for estimating the variation ranges of the system performances. The robustness estimations of the system performances are incorporated into the optimization formulation to obtain the nominal design variables, which could make the system performances relatively robust; therefore, the design robustness is estimated and improved in the optimization iteration process. The robust optimization method is applied to a general powertrain mounting system (PMS) to improve the design robustness of the PMS decoupling layout and frequency allocation. The optimization results show that the robust optimization method could effectively increase the decoupling ratios in the interested vertical and pitch directions, and the frequency allocation is more robust than that obtained using the traditional deterministic optimization. © 2012 The Korean Society of Automotive Engineers and Springer-Verlag Berlin Heidelberg.

Zhong M.-E.,Hunan Agricultural University | Zhou Z.,South China University of Technology
Solid State Ionics | Year: 2010

Pure olivine LiFePO4/C composite compounds are synthesized by carbothermal reduction (CTR) method using trigonal anhydrous FePO4 raw material. The physical and electrochemical properties of the prepared samples are investigated in comparison with those of a sample obtained from incompletely crystallized hydrous FePO4•2H2O. The olivine LiFePO4/C prepared with trigonal anhydrous FePO4 has a high discharge capacity of 142 mAh g- 1 at 0.1 C. The composite also displays a better rate capability, a higher discharge capacity and a more stable cycle-life than that synthesized with incompletely crystallized hydrous FePO4•2H2O. The improved electrochemical performance of trigonal anhydrous FePO4 synthesis samples originates mainly from the single-phase structure and small particle size. © 2010 Elsevier B.V. All rights reserved.

Cao H.,Guangdong Pharmaceutical University | Zhan H.,Guangdong Pharmaceutical University | Lin Y.,Guangdong Pharmaceutical University | Lin X.,Guangdong Pharmaceutical University | And 2 more authors.
Organic Letters | Year: 2012

A convenient method for the copper(I)-catalyzed arylation of substituted imidazo[1,2-a]pyridine has been developed. This method is applicable to a variety of aryl electrophiles, including bromides, iodides, and triflates. It represents the first general process for C-3 arylation of substituted imidazo[1,2-a]pyridine by Cu(I) catalysis to construct various functionalized imidazo[1,2-a]pyridine core π-systems. © 2012 American Chemical Society.

Chang L.,University of Illinois at Urbana - Champaign | Wu Z.,South China University of Technology
International Journal of Electrical Power and Energy Systems | Year: 2011

The stability and reliability of electrical power grids are indispensable to the continuous operation of modern cities and critical for preparedness, response, recovery and mitigation in emergence management. Because present power grids in China are often running near their critical operation points, they are especially vulnerable and sensitive to external disturbances such as hurricanes, earthquakes and terrorist attacks, which may trigger cascading failures or blackouts. This paper describes a quantitative investigation of the stability and reliability of power grids with a focus on cascading failures under external disturbances. The 118-bus (substation) power network in Hainan, China is employed as a case study to investigate the risk of cascading failure of the regional power grids. System performance and reliability of the power grids are evaluated under two hypothetical scenarios (seismic impact and intentional disturbance) that could trigger cascading failures. By identifying the most vulnerable (critical) edges and nodes, the robustness of the power network is evaluated under the triggered cascading failures. It is found that the system reliabilities could decline as much as 95% during the triggered cascading failure. This paper also explores the use of concepts from modern complex network theories such as state transition graph and characteristic length to understand the complex mechanism of cascading failures. The findings could be useful for power industries and emergency managers to evaluate the vulnerability of power systems, understand the risk of blackout induced by cascading failures, and improve the resilience of power systems to external disturbances. © 2011 Elsevier Ltd. All rights reserved.

A selective enrichment broth (SSL) was formulated to allow concurrent growth of 3 prominent food-borne pathogens: Salmonella enterica serovar Enteritidis, Staphylococcus aureus, and Listeria monocytogenes. Nalidixic acid, lithium chloride, and potassium tellurite were added as the selective agents, while sodium pyruvate and mannitol were employed as the supplemented elements. In the individual growth trial, the target pathogens were capable of growing in SSL to as high as 7-8 log(10) colony-forming units (CFU)/mL after 24 h incubation at 37 degrees C when being inoculated at 50-100 CFU/mL. In the simultaneous growth trial, the 3 combined target pathogens showed similar growth rates. The results show that SSL could support the successful simultaneous enrichment of 3 pathogens; however, SSL inhibited the growth of nontarget bacteria. In the artificial contaminated raw beef and ready-to-eat chicken, a high recovery of these 3 target pathogens was obtained in SSL. Finally, Salmonella Enteritidis, Staphylococcus aureus, and L. monocytogenes were detected from 710 suspicious food samples by SSL with real-time PCR, and no false-positive or -negative results were reported. In summary, SSL has been shown to be a suitable broth for the simultaneous detection of the 3 prominent food-borne pathogens by multipathogen detection on a single-assay platform.

Zhang H.,South China University of Technology
Immunogenetics | Year: 2014

Rhesus macaque is a very important animal model for various human diseases, especially for AIDS and vaccine research. The susceptibility and/or resistance to some of these diseases are related to the major histocompatibility complex (MHC). To gain insight into the MHC background and to facilitate the experimental use of Chinese rhesus macaques, Mamu-DPB1, Mamu-DQB1, and Mamu-DRB alleles were investigated in 30 Chinese rhesus macaques through gene cloning and sequencing. A total of 66 alleles were identified in this study, including 14 Mamu-DPB1, 20 Mamu-DQB1, and 30 Mamu-DRB alleles as well as 2 high-frequency Mamu-DPB1 alleles. Interestingly, one of the high-frequency Mamu-DPB1 alleles had been undocumented in earlier studies. Eleven of the other alleles, including four Mamu-DPB1, three Mamu-DQB1, and four Mamu-DRB alleles were also novel. Importantly, like MHC-DRB, more than two Mamu-DPB1 sequences per animal were detected in 13 monkeys, which suggested that they might represent gene duplication. Our data also indicated quite a few differences in the distribution of MHC class II alleles between the Chinese rhesus macaques and the previously reported Indian rhesus macaques. To our knowledge, our results revealed comprehensively the combination of MHC II alleles. This information will not only promote the understanding of Chinese rhesus macaque MHC polymorphism but will also facilitate the use of Chinese rhesus macaques in studies of human disease.

Saidi W.A.,University of Pittsburgh | Feng H.,Pennsylvania State University | Feng H.,South China University of Technology | Fichthorn K.A.,Pennsylvania State University
Journal of Physical Chemistry C | Year: 2013

We use dispersion-corrected density functional theory (DFT) to resolve the role of polyvinylpyrrolidone (PVP) in the shape-selective synthesis of Ag nanostructures by probing the interaction of its 2-pyrrolidone (2P) ring with Ag(100) and Ag(111). We employ two different semiempirical methods for including van der Waals (vdW) interactions in DFT calculations: DFT+vdWsurf and DFT-D2. We find that DFT-D2, in its original parametrization, overestimates the Ag metal dispersion interaction and causes an unphysical herringbone-like reconstruction of Ag(100). This can be remedied in DFT-D2 by using modified vdW parameters for Ag that account for many-body screening effects. The results obtained using DFT-D2 with the modified parameters agree well with experiment and with DFT+vdWsurf results. We find that 2P binds more strongly to Ag(100) than Ag(111), consistent with experiment. We analyze the origins of the surface-sensitive binding and find that vdW attraction is stronger on Ag(111), but the direct chemical bonding of 2P is stronger on Ag(100). We also study the influence of strain on binding energies and find that tension tends to lower the vdW interaction with the surfaces, while increasing the direct chemical-bonding interaction, consistent with the d-band center model. Overall, our work indicates that strain has little impact on the structure-directing capabilities of PVP, which is consistent with the fact that strained, 5-fold twinned Ag nanowires have extensive {100} facets and relative small {111} facets. © 2012 American Chemical Society.

Liu Y.-H.,South China University of Technology
Kongzhi Lilun Yu Yingyong/Control Theory and Applications | Year: 2014

The output tracking problem for a class of pure-feedback nonlinear systems is discussed. By introducing a novel coordinate transformation, we develop a state feedback controller via backstepping approach. The proposed control algorithm not only ensures the global asymptotic tracking, but also guarantees the boundedness of all the closed loop signals. Finally, a simulation example is given to demonstrate the effectiveness of the proposed control scheme.

Chen M.,Huazhong University of Science and Technology | Wan J.,South China University of Technology | Gonzalez S.,University of British Columbia | Liao X.,Huazhong University of Science and Technology | Leung V.C.M.,University of British Columbia
IEEE Communications Surveys and Tutorials | Year: 2014

Recent years have witnessed the emergence of machine-to-machine (M2M) networks as an efficient means for providing automated communications among distributed devices. Automated M2M communications can offset the overhead costs of conventional operations, thus promoting their wider adoption in fixed and mobile platforms equipped with embedded processors and sensors/actuators. In this paper, we survey M2M technologies for applications such as healthcare, energy management and entertainment. In particular, we examine the typical architectures of home M2M networks and discuss the performance tradeoffs in existing designs. Our investigation covers quality of service, energy efficiency and security issues. Moreover, we review existing home networking projects to better understand the real-world applicability of these systems. This survey contributes to better understanding of the challenges in existing M2M networks and further shed new light on future research directions. © 2014 IEEE.

Mei S.-W.,Tsinghua University | Zhu J.-Q.,South China University of Technology
Zidonghua Xuebao/Acta Automatica Sinica | Year: 2013

Taking into account the connotation and engineering demand of smart grid, this paper summarizes and extracts several basic scientific issues of smart grid during its construction and development process, including prediction, energy storage, control, dispatching, planning, assessment, and their common engineering game theory. These basic scientific issues respectively belong to the mathematics, control science or their cross discipline. The solution of these issues not only is the precondition of the realization of smart grid, but also can promote the application perspective of mathematics and control science. Thus, it possesses a significant value in the theory and engineering research. Copyright © 2013 Acta Automatica Sinica. All rights reserved.

Ma S.,South China University of Technology
Journal of Networks | Year: 2012

Cloud computing can provide critical services for business management, reducing IT costs and maintenance costs of hardware and software effectively. In the meanwhile, it can enable enterprises to access to professional IT solutions with less IT investment. Cloud computing is of great significance for the ICT industry of each country. It is now bringing enormous impact to the human society, especially the business world. In this paper, the basic concepts and the development of cloud computing were introduced, and then the current situation and development of cloud computing research from two aspects of technology and business were illustrated. Finally future trends of cloud computing were discussed. © 2012 ACADEMY PUBLISHER.

Li F.,South China University of Technology | Du T.C.,Chinese University of Hong Kong
Decision Support Systems | Year: 2014

Social networks have become increasingly popular in recent years. Among the many social networking tools, micro-blogging is one of the most unique and convenient because it is short, responsive, spontaneous and mobile. These properties allow micro-blogs to move beyond basic information sharing and make them a popular media for sharing opinions. In this study, we examine the persuasiveness of micro-blogs by developing a framework that first identifies opinion leaders and then analyzes their persuasiveness. To develop the framework, we download micro-blogs, blogger information and the relationships among them into a database, identify spammers, decompose communities into sub-nets, identify opinion leaders and conduct persuasiveness analyses. The results show the framework can identify opinion leaders and their opinions effectively. It was found that negative opinions are less persuasive than positive opinions, and positive opinion leaders are more aggressive in distributing positive messages than negative opinion leaders are in distributing negative messages. © 2014 Elsevier B.V.

Li C.-A.,South China University of Technology
Lecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics) | Year: 2013

This paper applies B-Cell algorithm (BCA) for credit scoring analysis problems. The proposed BCA-based method is combined with k-nearest neighbor (kNN) classifiers. In the algorithm, BCA is introduced to select the optimal feature subsets and kNNs are used to classify the investors in different groups representing different levels of credit in the classification phase. Experiments employing the benchmark data sets from UCI databases will be used to measure the performance of the algorithm. Its comparison with genetic algorithm, particle swarm optimization and ant colony optimization will be shown. © 2013 Springer-Verlag Berlin Heidelberg.

Wang L.,South China University of Technology
ChemPhysChem | Year: 2015

Benzyl alcohol (BA) is present in indoor atmospheres, where it reacts with OH radicals and undergoes further oxidation. A theoretical study is carried out to elucidate the reaction mechanism and to identify the main products of the oxidation of BA that is initiated by OH radicals. The reaction is found to proceed by H-abstraction from the CH2 group (25%) and addition to the ipso (60%) and ortho (15%) positions of the aromatic ring. The BA-OH adducts react further with O2 via the bicyclic radical intermediates-the same way as for benzene-forming mainly 3-hydroxy-2-oxopropanal and butenedial. If NOx is low, the bicyclic peroxy radicals undergo intramolecular H-migration, forming products containing OH, OOH, and CH2OH/CHO functional groups, and contribute to secondary organic aerosol (SOA) formation. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Chen Y.,South China University of Technology
Bioresource technology | Year: 2010

Modification of properties of old newspaper (ONP) deinked pulp with laccase and histidine was investigated. It was found that the optimum conditions for laccase-histidine treatment were: the concentration of laccase 0.9 U/g dry pulp, the concentration of histidine 1% relative to the dry pulp, room temperature, reaction time 1.5h, pH 7, the pulp consistency 5% and O(2) atmosphere. The results also showed that, in the optimum conditions, compared to the control pulp, the wet tensile strength, the carboxyl group content and water retention value of ONP treated with laccase and histidine were increased by 55.1%, 39.1% and 45.7%, respectively. Moreover, environmental scanning microscope images showed that more collapse and more fibrillation were observed on the laccase-histidine-treated fiber surface than the control samples, which led to form better bonding between fibers in handsheets resulting in the increase of the paper strength of laccase-histidine-treated ONP pulp. Copyright 2010 Elsevier Ltd. All rights reserved.

Liu H.,South China University of Technology
Langmuir : the ACS journal of surfaces and colloids | Year: 2011

This study demonstrated two in situ UV-vis spectrophotometric methods for rapid and temporally resolved measurements of cellulase adsorption onto cellulosic and lignocellulosic substrates during enzymatic hydrolysis. The cellulase protein absorption peak at 280 nm was used for quantification. The spectral interferences from light scattering by small fibers (fines) and particulates and from absorptions by lignin leached from lignocelluloses were corrected using a dual-wavelength technique. Wavelengths of 500 and 255 nm were used as secondary wavelengths for correcting spectral interferences from light scattering and absorption of leached lignin. Spectral interferences can also be eliminated by taking the second derivative of the measured spectra of enzymatic hydrolysate of cellulose or lignocelluloses. The in situ measured cellulase adsorptions in cellulose and lignocellulose suspensions by these two spectrophotometric methods showed general agreement with batch sampling assayed by the Bradford method. The in situ methods not only eliminated tedious batch sampling but also can resolve the kinetics of the initial adsorption process. The measured time-dependent cellulase adsorptions were found to follow pseudo-second-order kinetics.

Wei Z.,South-Central University for Nationalities | Yang Q.,South China University of Technology
Nonlinear Dynamics | Year: 2012

A generalized Sprott C system with only two stable equilibria is investigated by detailed theoretical analysis as well as dynamic simulation, including some basic dynamical properties, Lyapunov exponent spectra, fractal dimension, bifurcations, and routes to chaos. In the parameter space where the equilibria of the system are both asymptotically stable, chaotic attractors coexist with period attractors and stable equilibria. Moreover, the existence of singularly degenerate heteroclinic cycles for a suitable choice of the parameters is investigated. Periodic solutions and chaotic attractors can be found when these cycles disappear. © 2011 Springer Science+Business Media B.V.

Zhao H.Y.,South China University of Technology
Mini reviews in medicinal chemistry | Year: 2010

Chromatography technology has been widely applied in various aspects of the pharmacy research on traditional Chinese medicine (TCM). This paper reviews literatures, published in the past decades, on the separation of active component from TCM using chromatography technology. Ultra-performance liquid chromatography (UPLC), high-speed counter-current chromatography (HSCCC), rapid resolution liquid chromatography (RRLC), supercritical fluid chromatography (SFC), affinity chromatography (AC), and bio-chromatography (BC) are introduced in detail. Compared to high performance of high-performance liquid chromatography (HPLC), analysis time and solvent loss are significantly reduced by UPLC with increase in resolution and sensitivity. Some ingredients from nature derived drugs can be separated more completely by HSCCC, which has remarkable characteristics such as low cost, simple operation and no pollution. Trace components from complex systems can be selectively and efficiently separated and purified by AC, This feature makes it effective in isolation and identification of active components of Chinese herbs. Interference of some impurities could be excluded by BC. Active ingredients that are difficult to be separated by normal method can be acquired by SFC. Currently, application of novel chromatography techniques in TCM is still in the exploratory stage and many problems, such as preparation of stationary phase and detection, need to be solved.

Zhang L.-Z.,South China University of Technology
Energy | Year: 2016

Membrane-type Total heat exchangers (Heat and moisture recovery ventilators) have become key components for building energy conservation. Various materials and duct structures have been proposed to find an improved energy performance and a better economic return. However most previous optimizations of total heat exchangers are limited to deterministic design parameters whereas operational flexibility and feasibility were less concerned. In the real industrial world, each system experiences various disturbances due to changes in outside weather conditions, flow rates, size errors in equipment manufacturing, as well as uncertainties in interest rates and material properties. In this research, an approach, named the SLGA (Single-loop Genetic Algorithm) is proposed for the optimization of membrane-based total heat exchangers under severe uncertain operating conditions, which are represented by the reliabilities of design guidelines. The optimization problem selects eight uncertain parameters such as material type, duct structure, exchanger size, interest rate, etc, as the input variables, and the exchanger performance like economic return, sensible and latent effectiveness are selected as the objective functions respectively. Then the probabilistic constraints are transformed into deterministic forms by a single-loop deterministic method. The discrete and non-linear optimization problem is thereafter solved by a direction-based GA (genetic algorithm). © 2016 Elsevier Ltd.

Wang X.-T.,South China University of Technology
Physica A: Statistical Mechanics and its Applications | Year: 2011

This paper deals with the problem of discrete time option pricing using the fractional BlackScholes model with transaction costs. Through the 'anchoring and adjustment' argument in a discrete time setting, a European call option pricing formula is obtained. The minimal price of an option under transaction costs is obtained. In addition, the relation between scaling and implied volatility smiles is discussed. © 2011 Elsevier B.V. All rights reserved.

Wang Y.L.,South China University of Technology
Applied Mechanics and Materials | Year: 2014

CAI is a product of the era development and the problems in the process of its advancement which exist in the understanding and the resource reserve are inevitable. For these phenomena, not only the auxiliary and order principle are supposed to be established in the process of applying the computer technology in teaching, but also the CAI's application value ought to be reexamined. The specific training to teachers of different subjects needs to be strengthened and the construction of CAI network database should be consummated in time. © (2014) Trans Tech Publications, Switzerland.

Guo X.,Dalian University of Technology | Zhang W.S.,Dalian University of Technology | Wang M.Y.,Chinese University of Hong Kong | Wei P.,South China University of Technology
Computer Methods in Applied Mechanics and Engineering | Year: 2011

Considering stress-related objective or constraint functions in structural topology optimization problems is very important from both theoretical and application perspectives. It has been known, however, that stress-related topology optimization problem is challenging since several difficulties must be overcome in order to solve it effectively. Traditionally, SIMP (Solid Isotropic Material with Penalization) method was often employed to tackle it. Although some remarkable achievements have been made with this computational framework, there are still some issues requiring further explorations. In the present work, stress-related topology optimization problems are investigated via a level set-based approach, which is a different topology optimization framework from SIMP. Numerical examples show that under appropriate problem formulations, level set approach is a promising tool for stress-related topology optimization problems. © 2011 Elsevier B.V.

Kang W.,South China University of Technology
Pattern Recognition Letters | Year: 2012

In this paper, a vein pattern extraction method is proposed for biometric purposes. First, we utilize a maximal intra-neighbor difference (MIND) vector of all pixels in the original image to represent the relationship between each pixel and its neighborhood. Based on the MIND vectorgram (MINDVG), we define a maximal intra-neighbor vector difference (MIVND) as an index to unveil the preliminary vein pattern. Finally, we use an adaptive threshold to extract the venation pattern. The advantage of this method is that, by combining the features of vein imaging and the spatial properties of the MINDVG, the algorithm can efficiently overcome the negative factors of inhomogeneous thickness and blurry boundaries in vein imaging without preprocessing. Experiments on several images show that this method can directly extract intact and clear vein patterns with minimal noise. Therefore, the proposed algorithm has been validated in vein pattern extraction. © 2012 Elsevier B.V. All rights reserved.

Zhang L.-Z.,South China University of Technology
Journal of Heat Transfer | Year: 2011

Hollow fiber membrane contactors are used in air dehumidification. The benefit of this technology is that the liquid desiccant is not in a direct contact with the process air; therefore, the problem of liquid droplets crossover is prevented. The equations governing the heat and moisture transfer from the air to the liquid, through the membranes, are described. An analytical solution is obtained for the dimensionless differential equations, with which the dehumidification effectiveness could be estimated by simple algebraic calculations. It provides a convenient yet accurate tool for the component design and system optimization. The model is validated by experiments. The effects of varying operating conditions on system performance are investigated. It is found that the total number of transfer units for sensible heat and the overall Lewis number are the most dominant parameters influencing heat and mass transfer. © 2011 American Society of Mechanical Engineers.

Jiang Z.,Ningbo University of Technology | Jiang Z.-J.,South China University of Technology | Tian X.,Ningbo University of Technology | Chen W.,Ningbo University of Technology
Journal of Materials Chemistry A | Year: 2014

Amine functionalized holey graphene (AFHG), synthesized by the hydrothermal reaction of GO and ammonia and the subsequent KOH etching, has been used as a metal-free catalyst for the oxygen reduction reaction (ORR). It shows that AFHG is highly active for the ORR and exhibits higher electrocatalytic activity than graphene, nitrogen-doped graphene (NG) and amine functionalized graphene (AFG), which could be demonstrated from its higher current density and more positive half-wave and onset potentials for the ORR. Although AFHG also exhibits a slightly higher overpotential towards ORR, it is indeed more kinetically facile than the commercial JM Pt/C 40 wt%. Its higher electrochemical performance could be attributed to the presence of the electron donating group (e.g. amine) and a large number of holes in its sheet plate and the porous structure in its randomly stacked solid, which provide AFHG with higher electrical conductivity, more active edge N atoms and easier accessibility to oxygen, respectively. The stability measurements show that AFHG is more stable than graphene, NG, AFG and the JM Pt/C 40 wt% and exhibits higher immunity towards methanol crossover and CO poisoning than the JM Pt/C 40 wt%. Over 10 h of the ORR, AFHG loses only <7% of its original activity in the absence of methanol or CO, and the introduction of methanol or CO has no effect on its oxygen reduction activity, which makes it highly desirable as a metal-free catalyst for the ORR. © 2013 The Royal Society of Chemistry.

Huang Z.,Hong Kong Baptist University | Huang Z.,South China University of Technology | Bai F.,Hong Kong Baptist University
Nanoscale | Year: 2014

Minimization of helices opens a door to impose novel functions derived from the dimensional shrinkage of optical, mechanical and electronic devices. Glancing angle deposition (GLAD) enables one to deposit three-dimensional helical porous thin films (HPTFs) composed of separated spiral micro/nano-columns. GLAD integrates a series of advantageous features, including one-step deposition, wafer-scale production with mono-handedness of spirals, flexible engineering of spiral materials and dimensions, and the adaption to various kinds of substrates. Herein, we briefly review the fabrication of HPTFs by GLAD, specific growth mechanisms, physical properties in structures, mechanics and chiral optics, and the emerging applications in green energy. A prospective outlook is presented to illuminate some promising developments in enantioselection, bio-dynamic analyses, wirelessly-controlled drug delivery and mass production. © 2014 the Partner Organisations.

Li J.,South China University of Technology
Wei sheng wu xue bao = Acta microbiologica Sinica | Year: 2012

We analyzed the community and diversity of microorganisms involved in nitrification and denitrification of nitrogen cycle in typical aquaculture water in order to manage microbiological degradation of NH4+ and NO2-, to control nitrogen pollution and nitrogen cycle in shrimp-farming water. Samples were analyzed by Polymerase Chain Reaction-Denaturing Gradient Gel Electrophoresis (PCR-DGGE) graph. We constructed clone libraries of the typical sample based on the functional gene ammonia monooxygenase gene (amoA), nitrite oxidoreductase gene (nxrA), and nitrite reductase gene (nirS). These three libraries were analyzed by using Restriction Fragment Length Polymorphism (RFLP). Phylogenetic analysis showed that all sequences from amoA library were clustered into beta-Proteobacteria, including Nitrosomonas (81%) and Nitrosospira (19%). Clones from nxrA library were clustered into alpha-Proteobacteria and delta-Proteobacteria, including Nitrobacter (92%) and Desulfobacteraceae (8%). Clones from nirS library were clustered into alpha-Proteobacteria, beta-Proteobacteria and Actinobacteria. Beta-Proteobacteria was the dominant group that consisted of Azoarcus (25%), Brachymonas (5%), and Thauera (20%). In alpha-Proteobacteria group, Sophophora (10%), Polymorphum (25%), Ruegeria (5%) were detected. In the Actinobacteria group, Streptomyces (10%) was detected. Microorganisms involved in nitrification and denitrification of nitrogen cycle were abundant. In the aquaculture water, Nitrosomonas was the main performer of ammoxidation, Nitrobacter was the main performer of nitrification, and many kinds of populations played important roles in the denitrification.

Du F.,South China University of Technology
Chinese Journal of Mechanical Engineering (English Edition) | Year: 2016

Few study gives guidance to design weighting filters according to the frequency weighting factors, and the additional evaluation method of automotive ride comfort is not made good use of in some countries. Based on the regularities of the weighting factors, a method is proposed and the vertical and horizontal weighting filters are developed. The whole frequency range is divided several times into two parts with respective regularity. For each division, a parallel filter constituted by a low- and a high-pass filter with the same cutoff frequency and the quality factor is utilized to achieve section factors. The cascading of these parallel filters obtains entire factors. These filters own a high order. But, low order filters are preferred in some applications. The bilinear transformation method and the least P-norm optimal infinite impulse response (IIR) filter design method are employed to develop low order filters to approximate the weightings in the standard. In addition, with the window method, the linear phase finite impulse response (FIR) filter is designed to keep the signal from distorting and to obtain the staircase weighting. For the same case, the traditional method produces 0.3307 m·s-2 weighted root mean square (r.m.s.) acceleration and the filtering method gives 0.3119 m·s-2 r.m.s. The fourth order filter for approximation of vertical weighting obtains 0.3139 m·s-2 r.m.s. Crest factors of the acceleration signal weighted by the weighting filter and the fourth order filter are 3.0027 and 3.0111, respectively. This paper proposes several methods to design frequency weighting filters for automotive ride comfort evaluation, and these developed weighting filters are effective. © Chinese Mechanical Engineering Society and Springer-Verlag Berlin Heidelberg 2016.

Hu R.,HKUST Shenzhen Research Institute | Hu R.,Hong Kong University of Science and Technology | Leung N.L.C.,Hong Kong University of Science and Technology | Tang B.Z.,HKUST Shenzhen Research Institute | And 2 more authors.
Chemical Society Reviews | Year: 2014

Macromolecules with aggregation-induced emission (AIE) attributes are a class of luminescent materials that display enhanced emission when they are aggregated. They have attracted much attention because of their good solubility, processability, high emission efficiency in the aggregated states, etc. A large variety of AIE macromolecules have been developed, showing exponential growth of research interest in this field. This review summarizes the design principles and recent synthetic advancements, topological structures, as well as the frontiers of functionalities and potential applications of AIE macromolecules, especially fluorescence sensing, biological applications and optoelectronic applications, with an emphasis on the recent progress. New luminogenic systems without conventional chromophores displaying aggregated state emission are discussed. The highly dense clusters of heteroatoms with lone pair electrons in these systems may serve as the chromophore and are cited as "heterodox clusters". It is expected that the mechanistic insights into the AIE phenomena, based on the restriction of intramolecular motions and structure rigidification, can guide the future design of AIE materials with fascinating structures and functionalities. © 2014 The Royal Society of Chemistry.

Jiang Z.-J.,South China University of Technology | Jiang Z.,Ningbo University of Technology
ACS Applied Materials and Interfaces | Year: 2014

Nitrogen-doped holey graphene hollow microspheres (NHGHSs), synthesized through a template sacrificing method, were utilized as an anode material for lithium ion batteries (LIBs). Because of their specific microspherical hollow structure comprising nitrogen-doped holey graphene (NHG), the NHGHSs can exhibit reversible capacities of ∼1563 mAh g-1 at a low rate of 0.5 C and ∼254 mAh g-1 at a high rate of 20 C, which are significantly higher than the discharge capacity of the pristine graphene and other graphene-based carbonaceous materials. These, along with their good cycling stability, clearly demonstrate the great potential of using the NHGHSs as the anode material for LIBs of both high energy and power densities. We believe that the high specific surface area, holey structure of nitrogen-doped graphene, specific microspherical hollow structure, and increased interlayer spacing between the NHG nanosheets in their hollow walls are the main origins of their high electrochemical performance. © 2014 American Chemical Society.

Zhang A.,South China University of Technology
Polymer Bulletin | Year: 2010

Star-shaped hydroxy-terminated poly(d,l-lactide) (s-PDLLA), with arms of different lengths, were obtained by ring-opening polymerization (ROP) of d,l-lactide (LA) initiated by varied contents of pentaerythritol (PETH) in the presence of stannous octoate (Sn(Oct) 2), and were condensed with carboxyl-terminated poly(ethylene glycol) methyl ether (CT-mPEG, M n = 850 and 2,000) to afford four-arm star-shaped poly(d,l-lactide)-block- poly(ethylene glycol) copolymer (s-PDLLA-b-PEG). The polymers, including s-PDLLA, CT-mPEG, and s-PDLLA-b-PEG, were characterized and confirmed by 1H-NMR and 13C-NMR spectroscopy, fourier transform infrared spectroscopy (FT-IR), and gel permeation chromatography (GPC). © 2010 Springer-Verlag.

Wang T.,South China University of Technology | Lin B.,Minjiang University | Lin B.,Xiamen University
Renewable and Sustainable Energy Reviews | Year: 2014

China has become a net importer of natural gas as a result of rapidly increasing consumption in recent years. A production peak would exist since natural gas is an exhaustible resource. As conventional natural gas production peak approaches, the development of unconventional natural gas is attracting increasing attention. China's unconventional natural gas reserves are abundant, but exploration is still in its infancy stage. Thus, with the increasing quest for low-carbon development and China's natural gas price reform, studying the impacts of unconventional gas development on China's natural gas supply and price reform under different scenarios has practical significance. In this paper we predict China's natural gas production trends in different scenarios and forecast natural gas demand. This paper concludes that the exploitation of unconventional natural gas will greatly improve China's annual natural gas production, and delay the production peak year. This is important for China's natural gas supply security as it can decrease dependence on imported gas. Furthermore, as the cleanest fossil fuel, it will enable more time and space for renewable energy development given the many costs and controversies surrounding its development in China. © 2014 Elsevier Ltd.

Li Z.,Shanghai JiaoTong University | Li Z.,South China University of Technology | Yang C.,University of Plymouth
IEEE Transactions on Control Systems Technology | Year: 2012

The wheeled inverted pendulum (WIP) models have been widely applied in the transportation vehicles formed by a mobile wheeled inverted pendulum system with an operator (demonstrated in Fig.1 ). In this paper, we focus on the study of nonlinear control design for the WIP model-based vehicles, for which accurate dynamics could not be obtained beforehand due to the presence of uncertainties caused by the human operator as well as the vehicle. We develop an output feedback adaptive neural network (NN) control incorporating a linear dynamic compensator to achieve stable dynamic balance and tracking of the desired given trajectories. Comparison simulation studies demonstrate guaranteed tracking performance and stable dynamics balance in the presence of uncertainties and thus verify the efficiency of the developed nonlinear controller. © 2012 IEEE.

Liang J.-Z.,South China University of Technology
Polymer Testing | Year: 2011

Mechanical analysis was made based on the micro-mechanical model of short inorganic fibre reinforced polymer composites, and an expression for tensile strength was derived by introducing an interfacial strength factor. This equation was applied to estimate the tensile strength of short inorganic fibre reinforced polymer composites. The results showed that the relative tensile strength increased nonlinearly with increasing fibre volume fraction. Finally, the equation was preliminarily verified by using the measured tensile strength of both short glass fibre reinforced polycarbonate/acrylnitrile-butadiene- styrene copolymer composites and short carbon fibre reinforced polyamide composites reported in literature. Good agreement was found between the predictions and the experimental data. © 2011 Elsevier Ltd. All rights reserved.

Peng Z.,JiShou University | Chen F.,South China University of Technology
International Journal of Polymeric Materials and Polymeric Biomaterials | Year: 2011

Hydrogels were synthesized from acetic acid lignin by chemical crosslinking with NCO-terminated polyurethane ionomers (IPUI). The swelling ratio of hydrogels increased with pH. The hydrogel prepared at the mass ratio of m AAL/mIPUI: 0.35:1 presented maximum swelling ratio in pH 6.8 buffer solutions. The results of thermogravimetric analysis demonstrated that the thermal stability of the hydrogels is improved by the introduction of lignin. The data of release experiments for ammonium sulfate suggests that the hydrogels can be used as coating materials to prepare a slow-release fertilizer. Copyright © 2011 Taylor & Francis Group, LLC.

Liu X.,South China University of Technology
Sensors (Switzerland) | Year: 2012

The past few years have witnessed increased interest in the potential use of wireless sensor networks (WSNs) in a wide range of applications and it has become a hot research area. Based on network structure, routing protocols in WSNs can be divided into two categories: flat routing and hierarchical or clustering routing. Owing to a variety of advantages, clustering is becoming an active branch of routing technology in WSNs. In this paper, we present a comprehensive and fine grained survey on clustering routing protocols proposed in the literature for WSNs. We outline the advantages and objectives of clustering for WSNs, and develop a novel taxonomy of WSN clustering routing methods based on complete and detailed clustering attributes. In particular, we systematically analyze a few prominent WSN clustering routing protocols and compare these different approaches according to our taxonomy and several significant metrics. Finally, we summarize and conclude the paper with some future directions. © 2012 by the authors; licensee MDPI, Basel, Switzerland.

Liu X.,South China University of Technology
Journal of Applied Optics | Year: 2014

A brief and fundamental method for design of rotational symmetric reflector, called zoned method, was introduced based on non-imaging optics. The design idea of zoned method was presented: the light distribution of light source and luminaire were divided into pieces of zone bands by equal angle interval, the comparative analysis of flux difference of these two series of zone was did, and the relation between rays from light source and that from luminaire was determined, then the slope of the reflective curve at each reflective points was confirmed, finally the total shape of reflective curve was shown in 3D software. Moreover, detail design steps were described, and the precise design of reflector was verified with a high design matching ratio of 98.4%, by taking a special application for LED source for example.

Mei J.,South China University of Technology | Wu Y.,King Abdullah University of Science and Technology
New Journal of Physics | Year: 2014

A general design paradigm for a novel type of acoustic metasurface is proposed by introducing periodically repeated supercells on a rigid thin plate, where each supercell contains multiple cut-through slits that are filled with materials possessing different refractive indices but the same impedance as that of the host medium. When the wavelength of the incident wave is smaller than the periodicity, the direction of the transmitted wave with nearly unity transmittance can be chosen by engineering the phase discontinuities along the transverse direction. When the wavelength is larger than the periodicity, even though the metasurface is impedance matched to the host medium, most of the incident energy is reflected back and the remaining portion is converted into a surface-bound mode. We show that both the transmitted wave control and the high reflection with the surface mode excitation can be interpreted by a unified analytic model based on mode-coupling theory. Our general design principle not only supplies the functionalities of reflection-type acoustic metasurfaces, but also exhibits unprecedented flexibility and efficiency in various domains of wave manipulation for possible applications in fields like refracting, collimating, focusing or absorbing wave energy. © 2014 IOP Publishing Ltd and Deutsche Physikalische Gesellschaft.

To properly predict the mechanical response of a single-crystalline NiMnGa sample, the configurational forces on the twin interfaces in the sample have to be calculated accurately. However, the conventional displacement-based finite element (DB-FE) method usually yields large numerical errors in calculating the contact stress values on the twin interfaces, which will further influence the evaluations of the configurational forces. In this paper, an interface element (IE) method is incorporated into the conventional FE framework. Through this FE-IE method, the contact stress is treated as one of the primary unknowns on the twin interfaces. By solving the governing system of the model numerically, the contact stresses on the twin interfaces can be directly obtained, based on which the configurational forces can be calculated. The obtained results are further used to predict the global mechanical response of the NiMnGa sample. For a simple example, the theoretical values of the resultant contact forces and the configurational forces on the twin interfaces can be determined. By comparing the numerical results obtained from the DB-FE method and the FE-IE method with the theoretical values, it is found that the FE-IE method can generate more accurate numerical solutions. Furthermore, the influence of the cross-sectional shapes of NiMnGa samples on their mechanical response is investigated. © 2015 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Zhu D.S.,South China University of Technology
AIP Conference Proceedings | Year: 2010

Nanofluid is a kind of new engineering material consisting of solid nanoparticles with sizes typically of 1-100 nm suspended in base fluids. Due to the importance of thermophysical property on the heat transfer behavior of fluids, the surface tension and viscosity of Al2O3-H 2O nanofluids were investigated. The tests of nanoparticle concentrations ranged from 0 g/l to 1 g/l. The measurements of surface tension and viscosity were equipments based on the maximum bubble pressure method and a capillary viscometer, respectively. The results showed that the surface tension and the viscosity of nanofluids are both highly dependent on the temperature, which is the same to those of water. Because the nanoparticle concentration studied in this work is very low, so there is no obvious change for the viscosity and a maximum enhancement only about 5% for surface tension is obtained at a concentration of 1 g/l. © 2010 American Institute of Physics.

Chen J.-X.,South China University of Technology
Proceedings - 2014 IEEE Workshop on Electronics, Computer and Applications, IWECA 2014 | Year: 2014

The ordering level of a risk-averse retailer with budget constraints is considered in the paper. The retailer faces the random demand and borrows funds from a bank. Different from the existing research, under the conditional value-at-risk (CvaR) criterion in the framework of newsvendors, the optimal ordering level is obtained. It's found that the optimal ordering level of the risk-averse retailer with budget constraints decrease as the degree of risk aversion increases. The optimal ordering level of risk-averse retailer is lower than the risk neutral. The cause is also analyzed in the paper and then the sensibility analysis of the optimal ordering level is obtained with the parameter. Finally the numerical example is illustrated to prove the theoretical results. It is useful for the decision-makers in reality. © 2014 IEEE.

Su F.,South China University of Technology | Miao M.,CSIRO
Electrochimica Acta | Year: 2014

We present a simple design and a fabrication method for a high-performance, flexible, two-ply yarn supercapacitor based on irradiated CNT yarn and conductive polymer Poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate) (PEDOT/PSS). The CNT yarn is treated with gamma irradiation and the yarn surface is coated with the PEDOT/PSS to improve the energy storage capacitance of the as-spun yarn supercapacitor. A layer of PVA gel is coated on the surfaces of the CNT yarn and the composite yarn to form a separation layer containing electrolyte. The results show that the gamma irradiation greatly increases the electrical conductivity and improved the gram capacitance of the as-spun CNT two-ply yarn supercapacitor. The coating of PEDOT/PSS on the surface of the pure and irradiated CNT yarns further significantly improves the capacitance of the supercapacitors. The two-ply yarn supercapacitor constructed from the irradiation CNT yarn coated by PEDOT/PSS exhibits the large capacitance and high cyclic charge-discharge stability. Moreover, these two-ply yarn supercapacitors with fine diameters are highly flexible and can be easily woven or knitted into textile fabrics for uses in wearable electronics. © 2014 Elsevier Ltd.

Wang S.,Southwest University | Feng J.,South China University of Technology | Tse C.K.,Hong Kong Polytechnic University
IEEE Signal Processing Letters | Year: 2014

In this letter, a new class of cubature Kalman filters (CKF) based on a spherical simplex-radial rule is proposed to further improve accuracy and efficiency of the traditional CKF. The transformation group of the regular simplex and the moment matching method are utilized to compute the spherical and radial integrals, respectively. In addition, with the increase of the state dimension, the new CKF of the fifth degree uses fewer quadrature points than the traditional CKF with the same degree. Simulations on moments calculation and nonlinear state estimation show that the proposed CKFs can achieve higher accuracy and better efficiency than the traditional CKFs. © 2013 IEEE.

Zhang P.,Wuhan University of Science and Technology | Zhang W.-G.,South China University of Technology
Fuzzy Sets and Systems | Year: 2014

This paper considers a multiperiod fuzzy portfolio selection problem maximizing the terminal wealth imposed by risk control, in which the returns of assets are characterized by possibilistic mean values. A possibilistic absolute deviation is defined as the risk control of portfolio. A new multiperiod mean absolute deviation fuzzy portfolio selection model with transaction cost, borrowing constraints, threshold constraints and cardinality constraints is proposed. Based on the theory of possibility measure, the proposed model is transformed into a crisp nonlinear programming problem. Because of the transaction cost, the multiperiod portfolio selection is a dynamic optimization problem with path dependence. The discrete approximate iteration method is designed to obtain the optimal portfolio strategy, and is proved convergent. Finally, an example is given to illustrate the behavior of the proposed model and the designed algorithm using real data from the Shanghai Stock Exchange. © 2014 Elsevier B.V.

Jiang Z.-J.,South China University of Technology | Jiang Z.,Ningbo University of Technology
Journal of Materials Chemistry A | Year: 2014

Nitrogen-doped hollow graphene microspheres (NHGSs), synthesized through a procedure involving the calcination of graphene-oxide-wrapped amine-functionalized mesoporous silica nanoparticles (AFMSNs) and the subsequent removal of the AFMSNs via HF etching, have been employed as an electrocatalyst for the oxygen reduction reaction (ORR). It has been shown that these NHGSs are highly active toward ORR and exhibit higher electrocatalytic activity than graphene, nitrogen-doped graphene (NG), hollow graphene microspheres (HGSs), and JM Pt/C 40 wt%, and a comparable overpotential to JM Pt/C 40 wt%. Their high electrocatalytic activity could be attributed to the N-doped graphitic structure, which produces more active sites for the ORR, allowing the easier adsorption of oxygen and the subsequent reduction; and the specific microspherical hollow structure, which promotes the exposure of more surface area accessible to electrolytes, thereby allowing an easier diffusion of electrolytes into and out of the electrode catalyst layers. Their low overpotential for the ORR can be attributed to the specific microspherical hollow structure, which reduces the overpotential contribution from the mass transport limitation. The stability measurements show that NHGSs also exhibit a much higher stability than graphene, NG, HGSs, and JM Pt/C 40 wt%, and are immune to the methanol crossover and CO poisoning effects, which all together makes NHGSs highly attractive as an electrocatalyst for the ORR. This journal is © the Partner Organisations 2014.

Ge S.S.,University of Electronic Science and Technology of China | Ge S.S.,Interactive Digital Media Institute | Li Z.,South China University of Technology
IEEE Transactions on Automatic Control | Year: 2014

In this technical note, high dimensional integral Lyapunov functions are introduced for a class of MIMO nonlinear systems with unknown nonlinearities. First, adaptive state feedback control is presented based on the integral Lyapunov function. When only the output is measurable, by using a high-gain observer to estimate the derivative of the system output, adaptive output feedback control is also derived. The proposed control scheme provides a general approach to stabilize the MIMO plant without any restrictive assumptions. The control is continuous and ensures closed-loop stability and convergence of the tracking error to a small residual set. The size of the tracking error at steady state can be specified a priori and guaranteed by choosing the design parameters. © 1963-2012 IEEE.

Liu J.,Hong Kong Polytechnic University | Cheng K.W.E.,Hong Kong Polytechnic University | Zeng J.,South China University of Technology
IEEE Transactions on Industrial Electronics | Year: 2014

High frequency alternating current (HFAC) has already been applied in many power distribution systems due to outstanding merits. The circulation current control of the high frequency resonant inverter in parallel connection is more complicated than the low frequency counterpart. Methods from topology, modulation, and control perspectives have already been proposed; however, most of them are difficult to simultaneously accomplish the synchronization of magnitude and phase in high frequency circumstance. In this paper, a new modulation called as unified phase-shift modulation (PSM) is proposed to integrate the regulations of magnitude and phase. The unified PSM in steady state completely removes the modulation coupling between magnitude and phase so that the controllers of magnitude and phase can be independently accomplished without interactions. The operation scope of unified PSM is determined by zero voltage switching and total harmonic distortion of the resonant inverter. A prototype with two parallel inverters is established to verify the effectiveness with an operation frequency of 25 kHz and a full bridge output voltage of 40 V peak. The results of simulation and experiment prove that the unified PSM is superior over the existing PSM in HFAC circumstance. The controllers of magnitude and phase integrated by the proposed modulation can accomplish optimized output synchronization in the parallel single-stage resonant inverter. © 1982-2012 IEEE.

Wong A.,University of Toronto | Guo Y.,University of Toronto | Guo Y.,South China University of Technology | Parka C.B.,University of Toronto
Journal of Supercritical Fluids | Year: 2013

This study aims to elucidate the fundamental mechanisms of extensional stress-induced foaming phenomena by in situ observation of polypropylene foaming processes using a view-cell system. The foaming processes of polypropylene blown with supercritical carbon dioxide have been observed under static conditions as well as dynamic conditions where extensional strains were applied. A bubble growth-induced cell nucleation phenomenon, where existing cells triggered the generation of cells around them, was observed under static conditions due to the presence of crystals. In the dynamic cases, the applied extensional stresses caused foaming to occur in a more dispersed manner. The bubble growth-induced cell nucleation phenomenon was also observed, but it occurred at a later stage and the effect was less dominant. These fundamental understandings will provide guidance to improve processing strategies of plastic foaming processes. © 2013 Elsevier B.V. All rights reserved.

Liu Z.,South China University of Technology | Wen F.,Queensland University of Technology | Ledwich G.,Queensland University of Technology
IEEE Transactions on Power Delivery | Year: 2011

Some uncertainties, such as the uncertain output power of a plug-in electric vehicle (PEV) due to its stochastic charging and discharging schedule, that of a wind generation unit due to the stochastic wind speed, and that of a solar generating source due to the stochastic illumination intensity, volatile fuel prices, and future uncertain load growth could lead to some risks in determining the optimal siting and sizing of distributed generators (DGs) in distribution system planning. Given this background, under the chance constrained programming (CCP) framework, a new method is presented to handle these uncertainties in the optimal siting and sizing of DGs. First, a mathematical model of CCP is developed with the minimization of the DGs' investment cost, operating cost, maintenance cost, network loss cost, as well as the capacity adequacy cost as the objective, security limitations as constraints, and the siting and sizing of DGs as optimization variables. Then, a Monte Carlo simulation-embedded genetic-algorithm-based approach is employed to solve the developed CCP model. Finally, the IEEE 37-node test feeder is used to verify the feasibility and effectiveness of the developed model and method, and the test results have demonstrated that the voltage profile and power-supply reliability for customers can be significantly improved and the network loss substantially reduced. © 2011 IEEE.

Yuan Y.,National University of Singapore | Kwok R.T.K.,Hong Kong University of Science and Technology | Tang B.Z.,Hong Kong University of Science and Technology | Tang B.Z.,South China University of Technology | And 2 more authors.
Journal of the American Chemical Society | Year: 2014

Targeted drug delivery to tumor cells with minimized side effects and real-time in situ monitoring of drug efficacy is highly desirable for personalized medicine. In this work, we report the synthesis and biological evaluation of a chemotherapeutic Pt(IV) prodrug whose two axial positions are functionalized with a cyclic arginine-glycine-aspartic acid (cRGD) tripeptide for targeting integrin αvβ3 overexpressed cancer cells and an apoptosis sensor which is composed of tetraphenylsilole (TPS) fluorophore with aggregation-induced emission (AIE) characteristics and a caspase-3 enzyme specific Asp-Glu-Val-Asp (DEVD) peptide. The targeted Pt(IV) prodrug can selectively bind to αvβ3 integrin overexpressed cancer cells to facilitate cellular uptake. In addition, the Pt(IV) prodrug can be reduced to active Pt(II) drug in cells and release the apoptosis sensor TPS-DEVD simultaneously. The reduced Pt(II) drug can induce the cell apoptosis and activate caspase-3 enzyme to cleave the DEVD peptide sequence. Due to free rotation of the phenylene rings, TPS-DEVD is nonemissive in aqueous media. The specific cleavage of DEVD by caspase-3 generates the hydrophobic TPS residue, which tends to aggregate, resulting in restriction of intramolecular rotations of the phenyl rings and ultimately leading to fluorescence enhancement. Such noninvasive and real-time imaging of drug-induced apoptosis in situ can be used as an indicator for early evaluation of the therapeutic responses of a specific anticancer drug. © 2014 American Chemical Society.

Liang J.-Z.,South China University of Technology
Polymers for Advanced Technologies | Year: 2012

The interfacial stress and its distribution during impact of inorganic particulate-filled polymer composites were analyzed in the present paper by means of a three-dimensional (3D) finite element method, and the software used was the ANSYS/LS-DYNA (ANSYS Inc., Canonsburg, PA, USA). The simulation results showed that the normal stress, the shear stress, and the equivalent stress reached the maximum at the particle equator, and then they reduced quickly toward the direction of the particle pole along the interface between the particle and the matrix and achieved the minimum from about 0.5 to 2.0μm from the equator. Finally, they tended to gently or somewhat increase. Furthermore, the ways and mechanisms of the major fail or fracture of the polyphenylene sulfide (PPS)/calcium carbonate (CaCO 3) composites under impact load were discussed. The mechanism of impact fracture or failure of inorganic particle-filled PPS composites might be that the matrix around the neighboring inclusions will first yield owing to the stress concentration in the interface between the inclusion and the matrix to induce crazes and extend quickly. © 2011 John Wiley & Sons, Ltd.

Li H.,Guangzhou University | Shi Z.,Guangdong University of Technology | Jiang X.,Guangdong University of Technology | Zhu X.,South China University of Technology
Optics Letters | Year: 2011

We numerically study the gray solitons in parity-time (PT) symmetric potentials. Simulated results show that there are two kinds of gray solitons, the dip-shaped gray solitons and the hump-shaped solitons, and both of them can be stable. Hump-shaped solitons can always exist, but the grayness of a stable dip-shaped gray soliton should exceed a threshold value. More interesting, it is discovered that when propagating in PT symmetric potentials, the gray solitons have no transverse deviation, and this is a phenomenon different from the usual gray solitons. © 2011 Optical Society of America.

Su F.,South China University of Technology | Su F.,CSIRO | Miao M.,CSIRO
Nanotechnology | Year: 2014

Strong and flexible two-ply carbon nanotube yarn supercapacitors are electrical double layer capacitors that possess relatively low energy storage capacity. Pseudocapacitance metal oxides such as MnO2 are well known for their high electrochemical performance and can be coated on carbon nanotube yarns to significantly improve the performance of two-ply carbon nanotube yarn supercapacitors. We produced a high performance asymmetric two-ply yarn supercapacitor from as-spun CNT yarn and CNT@MnO2 composite yarn in aqueous electrolyte. The as-spun CNT yarn serves as negative electrode and the CNT@MnO2 composite yarn as positive electrode. This asymmetric architecture allows the operating potential window to be extended from 1.0 to 2.0 V and results in much higher energy and power densities than the reference symmetric two-ply yarn supercapacitors, reaching 42.0 Wh kg-1 at a lower power density of 483.7 W kg-1, and 28.02 Wh kg-1 at a higher power density of 19 250 W kg-1. The asymmetric supercapacitor can sustain cyclic charge-discharge and repeated folding/unfolding actions without suffering significant deterioration of specific capacitance. The combination of high strength, flexibility and electrochemical performance makes the asymmetric two-ply yarn supercapacitor a suitable power source for flexible electronic devices for applications that require high durability and wearer comfort. © 2014 IOP Publishing Ltd.

Ma H.,Shenzhen Polytechnic | Chan K.W.,Hong Kong Polytechnic University | Liu M.,South China University of Technology
IEEE Transactions on Industrial Informatics | Year: 2013

The intelligent control of power systems is one of the main tasks for realizing a smart grid. Because of the high-dimensional dynamics and discrete control of power systems, realizing an optimal control to support system voltages is a hard combinatorial optimization problem. In this paper, a new intelligent scheme based on a genetic learning progress for optimal voltage control is proposed. This learning control scheme combines the genetic algorithm (GA) with a memory which saves knowledge accumulated from past experiences. In each run of search by GA, past experiences in memory is exploited to speed up the searching of GA and improve the quality of the solutions while the knowledge in memory is also refined by the new solutions. With the help of this learning capability, a fast and self-healing voltage control is realized and the control performance can be improved gradually over time. A case study on the New England 39-bus power system showed that the purposed learning control can successfully prevent the system from voltage instability and at the same time a fast and adaptive system response is provided. © 2005-2012 IEEE.

Shi H.,National University of Singapore | Kwok R.T.K.,Hong Kong University of Science and Technology | Liu J.,Hong Kong University of Science and Technology | Xing B.,Nanyang Technological University | And 5 more authors.
Journal of the American Chemical Society | Year: 2012

Real-time monitoring of cell apoptosis could provide valuable insights into early detection of therapy efficiency and evaluation of disease progression. In this work, we designed and synthesized a new live-cell-permeable, fluorescent light-up probe for real-time cell apoptosis imaging. The probe is comprised of a hydrophilic caspase-specific Asp-Glu-Val-Asp (DEVD) peptide and a hydrophobic tetraphenylethene (TPE) unit, a typical fluorogen with aggregation-induced emission characteristics. In aqueous solution, the probe is almost nonfluorescent but displays significant fluorescence enhancement in response to caspase-3/-7, which are activated in the apoptotic process and able to cleave the DEVD moieties. This fluorescence "turn-on" response is ascribed to aggregation of cleaved hydrophobic TPE residues, which restricts the intramolecular rotations of TPE phenyl rings and populates the radiative decay channels. The light-up nature of the probe allows real-time monitoring of caspase-3/-7 activities both in solutions and in living cells with a high signal-to-noise ratio. The probe provides a new opportunity to screen enzyme inhibitors and evaluate the apoptosis-associated drug efficacy. © 2012 American Chemical Society.

Marsili E.,University of Minnesota | Sun J.,South China University of Technology | Bond D.R.,University of Minnesota
Electroanalysis | Year: 2010

The ability of Geobacter sulfurreducens to utilize electrodes as electron acceptors provides a system for monitoring mechanisms of electron transfer beyond the cell surface. This study examined the physiology of extracellular electron transfer during many stages of growth, and in response to short- and long-term changes in electron acceptor potential. When G. sulfurreducens was grown on planar potentiostat-controlled electrodes, the magnitude of early cell attachment increased with initial cell density. However, the first cells to attach did not demonstrate the same electron transfer rates as cells grown on electrodes. For example, following initial attachment of fumarate-grown cells, the electron transfer rate was 2 mA/mg protein, but increased to nearly 8 mA/mg protein within 6 h of growth. Once attached, all biofilms grew at a constant rate (doubling every 6 h), and sustained a high specific electron transfer rate and growth yield, while current density was below 300 mA/cm2. Beyond this point, the rate of current increase slowed and approached a stable plateau. At all phases, slow scan rate cyclic voltammetry of G. sulfurreducens showed a similar well-defined sigmoidal catalytic wave, indicating the general model of electron transfer to the electrode was not changing. Short-term exposure to reducing potentials (3 h) did not alter these characteristics, but did cause accumulation of electrons which could be discharged at potentials above -0.1 V. Sustained growth at lower potentials (0.16 V) only slightly altered the pattern of detectable redox species at the electrode, but did eliminate this pattern of discharge from the biofilm. Single-turnover voltammetry of colonized electrodes showed at least 3 redox couples at potentials similar to other recent observations, with redox protein coverage of the electrode on the order of ca. 1 nmol/cm2. The consistent electrochemistry, growth rate, and growth yield of the G. sulfurreducens biofilm at all stages suggests an initial phase where cells must optimize attachment or electron transfer to a surface, and that after this point, the rate of electron production by cells (rate electrons are delivered to the external surface) remains rate limiting compared to the rate electrons can be transferred between cells, and to electrodes. © 2010 Wiley-VCH Verlag GmbH&Co.

Zhou B.,Hong Kong Polytechnic University | Chan K.W.,Hong Kong Polytechnic University | Yu T.,South China University of Technology | Chung C.Y.,Hong Kong Polytechnic University
IEEE Transactions on Power Systems | Year: 2013

This paper proposes a novel multiple group search optimizer (MGSO) to solve the highly constrained multiobjective power dispatch (MOPD) problem with conflicting and competing objectives. The algorithm employs a stochastic learning automata based synergistic learning to allow information interaction and credit assignment among multi-groups for cooperative search. An alternative constraint handling, which separates constraints and objectives with different searching strategies, has been adopted to produce a more uniformly-distributed Pareto-optimal front (PF). Moreover, two enhancements, namely space reduction and chaotic sequence dispersion, have also been incorporated to facilitate local exploitation and global exploration of Pareto-optimal solutions in the convergence process. Lastly, Nash equilibrium point is first introduced to identify the best compromise solution from the PF. The performance of MGSO has been fully evaluated and benchmarked on the IEEE 30-bus 6-generator system and 118-bus 54-generator system. Comparisons with previous Pareto heuristic techniques demonstrated the superiority of the proposed MGSO and confirm its capability to cope with practical multiobjective optimization problems with multiple high-dimensional objective functions. © 2013 IEEE.

Bai P.,South China Normal University | Tang T.,South China University of Technology | Tang B.,South China Normal University
Applied Thermal Engineering | Year: 2013

Three heat sinks with porous-coated parallel microchannels were fabricated by using a solid-state sintering method. The enhanced flow boiling of anhydrous ethanol in the porous-coated microchannels was systematically studied and compared to that of bare microchannels. The changes in pressure drop, flow boiling instability and flow boiling heat transfer performances caused by the introducing of porous coatings were discussed. The effect of particle size on pressure drop and heat transfer performance was also studied. The porous-coated microchannels showed significant mitigation of flow boiling instability, which was explained by the changes in bubble dynamics. Dramatic enhancement of flow boiling heat transfer in the porous-coated microchannels was obtained. The enhancement from porous coatings showed dependence on particle size and diminished with the increase of vapor quality. © 2013 Elsevier Ltd. All rights reserved.

He X.,South China University of Technology
Sheng wu yi xue gong cheng xue za zhi = Journal of biomedical engineering = Shengwu yixue gongchengxue zazhi | Year: 2010

In order to simplify the distal femoral comminuted fracture surgery and improve the accuracy of the parts to be reset, a kind of surgery orienting model for the surgery operation was designed according to the scanning data of computer tomography and the three-dimensional reconstruction image. With the use of DiMetal-280 selective laser melting rapid prototyping system, the surgery orienting model of 316L stainless steel was made through orthogonal experiment for processing parameter optimization. The technology of direct manufacturing of surgery orienting model by selective laser melting was noted to have obvious superiority with high speed, precise profile and good accuracy in size when compared with the conventional one. The model was applied in a real surgical operation for thighbone replacement; it worked well. The successful development of the model provides a new method for the automatic manufacture of customized surgery model, thus building a foundation for more clinical applications in the future.

Shen Y.,South China University of Technology | Shen Y.,Nanyang Technological University | Lua A.C.,Nanyang Technological University
Applied Catalysis B: Environmental | Year: 2015

Nickel and nickel-copper alloy supported on carbon nanotubes (CNTs) were examined as catalysts for hydrogen production by methane decomposition. The Ni/CNT and Ni-Cu/CNT catalysts were characterized using field emission scanning electron microscopy, energy dispersive X-ray microscopy, transmission electron microscopy and X-ray diffraction. The performance of the catalysts was dependent on the catalyst composition and reaction temperature. The Ni78Cu22/CNT catalyst exhibited the excellent catalytic performance with a stable methane conversion of 0.8 at 700°C, a carbon yield rate of 0.08gC/(mingNi) at 743°C and a carbon yield of 602gC/gNi at 700°C. Carbon materials with various morphologies, i.e., herringbone carbon nanofibers (CNFs), platelet CNFs, bamboo-shaped CNFs, branched CNFs, multi-branched CNFs and onion-like carbons, depending on the catalyst composition and reaction temperature, were obtained. The morphology of the produced carbon material was correlated with the growth mechanism of the carbon material on the catalyst. © 2014 Elsevier B.V.

Wang X.,Hefei University of Technology | Liu G.,Hefei University of Technology | Zhang G.,South China University of Technology
Langmuir | Year: 2011

Poly[(2-dimethylamino)ethyl methacrylate] (PDEM) is completely charged, partially charged, and uncharged at pH 4, 7, and 10, respectively. We have investigated the salt effects on the conformational change of PDEM chains grafted on a surface at different pH by using quartz crystal microbalance with dissipation (QCM-D) and surface plasmon resonance (SPR). The changes in frequency (Δf) and dissipation (ΔD) in QCM-D measurements demonstrate that the conformational behavior is governed by counterion condensation at pH 4 and 7 but by nonelectrostatic anion adsorption at pH 10. The addition of Na2SO4 induces more collapse of the grafted layer than that of NaClO3 at pH 4 and 7. However, they have a similar effect at pH 10. The shift of resonance unit (ΔRU) in SPR measurements reflects the changes of layer thickness and layer refractive index. At pH 4, ΔRU decreases with ionic strength in the presence of Na 2SO4, indicating the decrease of layer thickness or the chain collapse. However, ΔRU exhibits a minimum as the ionic strength increases in the case of NaClO3. This is because the effects of the layer thickness and refractive index are dominant in the low and high ionic strength regimes, respectively. At pH 7, ΔRU slightly varies with ionic strength in the case of either Na2SO4 or NaClO 3, indicating that the effects of the layer thickness and refractive index are comparable during the layer collapse. At pH 10, the shift in ΔRU suggests that the nonelectrostatic anion adsorption governs the conformational behavior of the PDEM chains. © 2011 American Chemical Society.

Zhang H.,South China University of Technology
Journal of Applied Physics | Year: 2013

We have investigated both the polarization rotations and the field induced phase transitions in [100], [110], and [111]-oriented PZN-4.5%PT single crystals on the basis of the single domain polarization rotation model. The dependence of the polarization, the electrostrictive response, and the lattice parameters in ferroelectric crystals on the field has been numerically obtained. The numerical results, in agreement with the experimental data, have shown that the polarization rotation is strongly dependent on the initial polarization state and polarization history in the single crystals, and the rhombohedral- monoclinic-tetragonal phase transitions occur for E//[100]. © 2013 AIP Publishing LLC.

Zeng X.,South China University of Technology
Wei sheng wu xue bao = Acta microbiologica Sinica | Year: 2012

To explore whether the S2P homolog, sll0862 in cyanobacterium Synechocystis sp. PCC 6803 is involved in stress response. We compared the growth curve of sll0862 mutant and the wild type under high temperature or oxidative stress. We detected chlorophyll fluorescence under heat shock or oxidative stress by water-PAM (pulse amplitude modulated fluorometry). Under normal condition of autotrophic growth, the growth curve of sll0862 mutant was similar with that of the wild type. However, after heat treatment at 48 degrees C for 30 minutes, the survival rate of sll0862 mutant was lower than that of the wild type. The sll0862 mutant hardly survived when incubated in 1 mmol/ L H2O2, whereas the wild type is not affected. Meanwhile, different chlorophyll fluorescence under stress between the wild type and the mutant was observed using water-PAM. These results indicate that the S2P homology sll0862 plays an important role in response to heat shock and oxidative stress in cyanobacterium Synechocystis sp. PCC 6803, which provides foundation for further research of the sll0862 function and mechanism.

Zhang H.,South China University of Technology
Journal of Applied Physics | Year: 2013

We have proposed the polarization rotation theory to understand the underlying physics of the large piezoelectric effect in ferroelectric crystals by referring to the coherent rotation model in ferromagnetism. When both the electric field energy and crystalline anisotropy energy are taken into account, the polarization in BaTiO3 crystal can be rotated toward the field direction. The numerical results are in agreement with the experimental observations and have indicated the highly anisotropic polarization rotations and the field-induced-phases with different symmetries in the crystal. This theory is helpful for understanding the polarization reversal and the electromechanical effect in ferroelectric materials. © 2013 AIP Publishing LLC.

Liang J.-Z.,South China University of Technology
Journal of Applied Polymer Science | Year: 2013

In this study, the factors affecting the Young's modulus of inorganic fibrous particulate-reinforced polymer composites were analyzed, and a new expression of the Young's modulus was derived and was based on a simplified mechanical model. This equation was used to estimate the composite Young's modulus. The estimated relative Young's modulus increased nonlinearly with increasing filler volume fraction. Finally, we verified the equation preliminarily by quoting the measured Young's modulus values of poly(butylene terephthalate)/wollastonite, polypropylene/wollastonite, and nylon 6/wollastonite composites reported in the literature. Good agreement was shown between the predictions and the experimental data of the relative Young's modulus values for these three composite systems. © 2013 Wiley Periodicals, Inc.

Zhang H.,South China University of Technology
Journal of Applied Physics | Year: 2013

We have investigated the polarization rotation and phase transition in [100]-oriented PZN-4.5%PT and PZN-8%PT single crystals on the basis of the single domain polarization rotation model. The dependence of both the polarization and the electrostrictive responses in ferroelectric crystals on the field at various temperatures has been numerically obtained. The numerical results have shown that both the polarization rotation and the phase transition are in nature determined by the electro-crystalline anisotropy constants. These constants are dependent on the composition of PZN-PT solution and ferroelectric properties of its components. Without considering the piezoelectric effect, the numerical results are in agreement with the experimental data. This paper is useful for better understanding of the polarization switching and the phase transition in ferroelectric crystals. © 2013 AIP Publishing LLC.

Guo L.,South China University of Technology
IEICE Transactions on Information and Systems | Year: 2013

In the image classification applications, the test sample with multiple man-handcrafted descriptions can be sparsely represented by a few training subjects. Our paper is motivated by the success of multitask joint sparse representation (MTJSR), and considers that the different modalities of features not only have the constraint of joint sparsity across different tasks, but also have the constraint of local manifold structure across different features. We introduce the constraint of local manifold structure into the MTJSR framework, and propose the Locality-constrained multi-task joint sparse representation method (LC-MTJSR). During the optimization of the formulated objective, the stochastic gradient descent method is used to guarantee fast convergence rate, which is essential for large-scale image categorization. Experiments on several challenging object classification datasets show that our proposed algorithm is better than the MTJSR, and is competitive with the state-of-the-art multiple kernel learning methods. Copyright © 2013 The Institute of Electronics, Information and Communication Engineers.

Liang J.Z.,South China University of Technology
Journal of Thermoplastic Composite Materials | Year: 2011

On the basis of Ashelby's method and Mori's work, a simplified equation describing the relationship between the storage modulus and filler volume fraction for polymer composites filled with inorganic particles was proposed. The dynamic mechanical properties of the low-density polyethylene composites filled with glass beads were measured using a Du Pont dynamical mechanical analysis instrument in temperature range from -150°C to 100°C. It was found that the storage modulus increased roughly nonlinearly with an increase of the glass bead weight fraction. The relative storage modulus of these composites was estimated by means of this equation under experimental conditions, and compared with the experimental data. The results showed that the predictions of this equation were roughly consistent with the measured data and were close to the estimations of the equations published in literature. Furthermore, this equation was also verified by quoting some experimental data of quartz powder filled epoxy composites from reference. © 2010 The Author(s).

Zhang X.-N.,South China University of Technology
Huanan Ligong Daxue Xuebao/Journal of South China University of Technology (Natural Science) | Year: 2012

For asphalt mixtures, the digital image technology has been used to obtain the internal structure, analyze the volume parameters and complete the computer-assisted design. These aspects have been hot research topics in the asphalt pavement technology area. In this paper, the relevant research results achieved by the author and his team are introduced, focusing on: (1) the statistics of the volumetric component of asphalt mixtures, the identification of the different components of asphalt mixtures and the extraction of the morphological characteristics of coarse aggregates, which are all based on the 2D digital image technology; (2) the 3D reconstruction of the internal structure of asphalt mixtures; and (3) the virtual mechanics test method. Meanwhile, the cases for the industrial applications of these research results are presented.

Deng Y.,CAS Institute of Theoretical Physics | Deng Y.,Henan Normal University | Cheng J.,South China University of Technology | Jing H.,Henan Normal University | And 2 more authors.
Physical Review Letters | Year: 2012

We propose an experimental scheme to create spin-orbit coupling in spin-3 Cr atoms using Raman processes. By employing the linear Zeeman effect and optical Stark shift, two spin states within the ground electronic manifold are selected, which results in a pseudospin-1/2 model. We further study the ground state structures of a spin-orbit-coupled Cr condensate. We show that, in addition to the stripe structures induced by the spin-orbit coupling, the magnetic dipole-dipole interaction gives rise to the vortex phase, in which a spontaneous spin vortex is formed. © 2012 American Physical Society.

Feng B.,South China University of Technology | Fan Z.-P.,Northeastern University China | Li Y.,City University of Hong Kong
International Journal of Production Economics | Year: 2011

Although supplier selection in multi-service outsourcing is a very important decision problem, research concerning this issue is still relatively scarce. This paper proposes a decision method for selecting a pool of suppliers for the provision of different service process/product elements. It pioneers the use of collaborative utility between partner firms for supplier selection. A multi-objective model is built to select desired suppliers. This model is proved to be NP-hard, so we develop a multi-objective algorithm based on Tabu search for solving it. We then use an example to show the applicability of the proposed model and algorithm. Extensive computational experiments are also conducted to further test the performance of the proposed algorithm. © 2011 Elsevier B.V. All rights reserved.

Wen D.-H.,Texas A&M University-Commerce | Wen D.-H.,South China University of Technology | Newton W.G.,Texas A&M University-Commerce | Li B.-A.,Texas A&M University-Commerce
Physical Review C - Nuclear Physics | Year: 2012

Using a simple model of a neutron star with a perfectly rigid crust constructed with a set of crust and core equations of state that span the range of nuclear experimental uncertainty in the symmetry energy, we calculate the instability window for the onset of the Chandrasekhar-Friedmann-Schutz instability in r-mode oscillations for canonical neutron stars (1.4M) and massive neutron stars (2.0M). In these models the crust-core transition density, and thus crustal thickness, is calculated consistently with the core equation of state (EOS). The EOSs are calculated using a simple model for the energy density of nuclear matter and probe the dependence on the symmetry energy by varying the slope of the symmetry energy at saturation density L from 25 MeV (soft symmetry energy and EOS) to 115 MeV (stiff symmetry energy and EOS) while keeping the EOS of symmetric nuclear matter fixed. For the canonical neutron star, the lower bound of the r-mode instability window is reduced in frequency by 150 Hz from the softest to the stiffest symmetry energy used, independent of mass and temperature. The instability window also drops by 100 Hz, independent of EOS when the mass is raised from 1.4M to 2.0M. Where temperature estimates are available, the observed neutron stars in low-mass x-ray binaries (LMXBs) have frequencies below the instability window for the 1.4M models, while some LMXBs fall within the instability window for 2.0M stars if the symmetry energy is relatively stiff, indicating that a softer symmetry energy is more consistent with observations within this model. Thus we conclude that smaller values of L help stabilize neutron stars against runaway r-mode oscillations. The critical temperature, below which no star can reach the instability window without exceeding its Kepler frequency, varies by nearly an order of magnitude from soft to stiff symmetry energies. When the crust thickness and core EOS are treated consistently, a thicker crust corresponds to a lower critical temperature, the opposite result to previous studies in which the transition density was independent of the core EOS. © 2012 American Physical Society.

Shan C.,South China University of Technology
Yingyong Jichu yu Gongcheng Kexue Xuebao/Journal of Basic Science and Engineering | Year: 2011

The effects of two strengthening methods were analysised based on comparing the midspan deflections and the strain changes of original tensile reinforcement, later bonded steel plate or CFRP, original concrete superface and later added concrete superface with bending moment, through two groups of reinforcement testing that simple supported RC beams were preloaded to cracking under the same conditions, and then reinforced by bonding steel plate or CFRP on the tensile side and increasing section area on the pressure side. The results show that the strengthening of bonding steel plate is obviously superior to bonding CFRP in the improvements of the old and new material stress, the beam stiffness and the bending capacity, so the latter is fit for anti-cracking reinforcement, not for the strengthening of increasing bending capacity or resistance to deformation capacity. On the other side, the strengthening of bonding steel plate by daubing is inferior to bonding CFRP in inhibiting cracks development. As to the balanced-reinforced beam, the high strength of fiber is hardly play.

Liang J.-Z.,South China University of Technology
Journal of Polymer Engineering | Year: 2013

Polyformaldehyde (POM)/ethylene-vinyl acetate copolymer (EVA)/high-density polyethylene (HDPE) composites filled with nanometer calcium carbonate (nano- CaCO3) were prepared using a twin-screw extruder. The effects of load and temperature on the melt extrudate swell behavior of the composites were investigated, by using a melt flow rate instrument under experimental conditions, with temperatures ranging from 170°C to 220°C and loads varying from 1.2 kg to 12.5 kg. The results showed that the melt die-swell ratio (B) of the composites decreased linearly with a rise of temperature as the load was fixed, while it increased nonlinearly with increase in the melt volume flow rate (MVR) and load, when the test temperature was constant; they also showed that B is a quadratic function of shear rate or shear stress. The value of B increased nonlinearly with an increase of the HDPE weight fraction (φ) as the temperature was constant, and the temperature sensitivity of B to φ was insignificant, while the effect of load was significant. The correlation between B and φ obeyed a quadratic equation. © 2013 Walter de Gruyter GmbH & Co. KG, Berlin/Boston.

Wang C.,South China University of Technology | Chen T.,Guangdong University of Technology
IEEE Transactions on Neural Networks | Year: 2011

Detection of small faults is one of the most important and challenging tasks in the area of fault diagnosis. In this paper, we present an approach for the rapid detection of small oscillation faults based on a recently proposed deterministic learning (DL) theory. The approach consists of two phases: the training phase and the test phase. In the training phase, the system dynamics underlying normal and fault oscillations are locally accurately approximated through DL. The obtained knowledge of system dynamics is stored in constant radial basis function (RBF) networks. In the diagnosis phase, rapid detection is implemented. Specially, a bank of estimators are constructed using the constant RBF neural networks to represent the training normal and fault modes. By comparing the set of estimators with the test monitored system, a set of residuals are generated, and the average L1 norms of the residuals are taken as the measure of the differences between the dynamics of the monitored system and the dynamics of the training normal mode and oscillation faults. The occurrence of a test oscillation fault can be rapidly detected according to the smallest residual principle. A rigorous analysis of the performance of the detection scheme is also given. The novelty of the paper lies in that the modeling uncertainty and nonlinear fault functions are accurately approximated and then the knowledge is utilized to achieve rapid detection of small oscillation faults. Simulation studies are included to demonstrate the effectiveness of the approach. © 2011 IEEE.

Solvent extraction of palladium (II) from hydrochloric acid solution with 2-n-octyl-4-isothiazolin-3-one (OIT)/cyclohexane was studied. Effects of different parameters on extraction efficiency were evaluated. 99.96 % and 98.26 % palladium (II) could be effectively extracted with 0.018 mol·L -1 OIT/cyclohexane of 0.1 and 4.0 mol·L-1 HCl medium, respectively. Nonpolar solvent and low acidity could improve the extracting efficiency, and successfully strip palladium (II) from the loaded organic phase was achieved with 0.5 mol·L-1 (NH 2)2CS solution. It was proposed that the extraction of Pd complexes from HCl medium proceeded through the ion-association mechanism by slope method, NMR and FT-IR spectra. © 2013 The Nonferrous Metals Society of China and Springer-Verlag Berlin Heidelberg.

Lin W.-W.,South China University of Technology
Huanan Ligong Daxue Xuebao/Journal of South China University of Technology (Natural Science) | Year: 2012

In the existing default data placement strategy for Hadoop, much time is needed to restore data from a remote DataNode when the local replicas become unavailable, and the load balancing may be destroyed due to the random selection of DataNode for data storage. In order to solve these problems, an improved data placement strategy is proposed, which chooses the most appropriate DataNode to place remote replicas according to the scheduling evaluation value of each DataNode based on DataNodes' network distance and data load. Thus, the load balancing for data storage is implemented and excellent data transmission is achieved. The proposed data placement strategy is then implemented in the Hadoop platform and the results show that the proposed strategy is superior to the existing default data placement strategy because it improves the local balancing for data storage and reduces the time for data placement.

Ding D.,National University of Singapore | Li K.,Institute of Materials Research and Engineering of Singapore | Liu B.,National University of Singapore | Liu B.,Institute of Materials Research and Engineering of Singapore | And 3 more authors.
Accounts of Chemical Research | Year: 2013

Fluorescent bioprobes are powerful tools for analytical sensing and optical imaging, which allow direct visualization of biological analytes at the molecular level and offer useful insights into complex biological structures and processes. The sensing and imaging sensitivity of a bioprobe is determined by the brightness and contrast of its fluorescence before and after analyte binding. Emission from a fluorophore is often quenched at high concentration or in aggregate state, which is notoriously known as concentration quenching or aggregation-caused quenching (ACQ). The ACQ effect limits the label-to-analyte ratio and forces researchers to use very dilute solutions of fluorophores. It compels many probes to operate in a fluorescence "turn-off" mode with a narrow scope of practical applications.The unique aggregation-induced emission (AIE) process offers a straightforward solution to the ACQ problem. Typical AIE fluorogens are characterized by their propeller-shaped rotorlike structures, which undergo low-frequency torsional motions as isolated molecules and emit very weakly in solutions. Their aggregates show strong fluorescence mainly due to the restriction of their intramolecular rotations in the aggregate state. This fascinating attribute of AIE fluorogens provides a new platform for the development of fluorescence light-up molecules and photostable nanoaggregates for specific analyte detection and imaging.In this Account, we review our recent AIE work to highlight the utility of AIE effect in the development of new fluorescent bioprobes, which allows the use of highly concentrated fluorogens for biosensing and imaging. The simple design and fluorescence turn-on feature of the molecular AIE bioprobes offer direct visualization of specific analytes and biological processes in aqueous media with higher sensitivity and better accuracy than traditional fluorescence turn-off probes. The AIE dot-based bioprobes with different formulations and surface functionalities show advanced features over quantum dots and small molecule dyes, such as large absorptivity, high luminosity, excellent biocompatibility, free of random blinking, and strong photobleaching resistance. These features enable cancer cell detection, long term cell tracing, and tumor imaging in a noninvasive and high contrast manner. Recent research has significantly expanded the scope of biological applications of AIE fluorogens and offers new strategies to fluorescent bioprobe design. We anticipate that future development on AIE bioprobes will combine one- or multiphoton fluorescence with other modalities (e.g., magnetic resonance imaging) or functionalities (e.g. therapy) to fully demonstrate their potential as a new generation of theranostic reagent. In parallel, the advances in molecular biology will provide more specific bioreceptors, which will enable the development of next generation AIE bioprobes with high selectivity and sensitivity for molecular sensing and imaging. © 2013 American Chemical Society.

Wang Y.,South China University of Technology
Zeitschrift fur Angewandte Mathematik und Physik | Year: 2016

In this paper, we consider a model problem arising from a classical planar Heisenberg ferromagnetic spin chain$-\Delta u + (\lambda + \varepsilon') u \mp \Delta \sqrt{1-u^{2}}\frac{u}{\sqrt{1- u^{2}}} - \varepsilon'\frac{u}{\sqrt{1 - u^{2}}} = 0, \, x \in \mathbb{R}^{3},-Δu+(λ+ε′)u∓Δ1-u2u1-u2-ε′u1-u2=0,x∈R3, where λ and ε′are real constants. By variational methods and perturbation arguments, we study the existence of positive classical solutions. Our results generalize the previous results in one-dimensional space given by Brüll et al. [4]. © 2016, Springer International Publishing.

Ma Z.,South China University of Technology
Chemistry (Weinheim an der Bergstrasse, Germany) | Year: 2012

The design and preparation of luminescent drug carriers has been a prosperous area of research for many years. However, the excitation and/or emission wavelength of such luminescent drug carriers haven't been optimized in the so-called human "near infrared (NIR) optical window", thus restricting their practical applications. Herein, we report the synthesis of electrospun porous YAG:Nd(3+) (neodymium-doped yttrium aluminum garnet) fibers with both excitation and emission in the "NIR optical window" as luminescent drug carriers. The YAG:Nd(3+) porous fibers were characterized by SEM, TEM, XRD, scanning transmission electron microscopy-energy-dispersive X-ray spectroscopy (STEM-EDX), and photoluminescence (PL). Ibuprofen (IBU) was used as a model drug to evaluate the drug-loading capacities and release profiles of the samples. BMSCs (bone mesenchymal stem cells) were used as model human cells to investigate cytotoxicity. Our results indicated that the YAG:Nd(3+) fibers possessed a fine, irregularly porous fibrous morphology with an average diameter of 378 nm. The florescence of the sample (1064 nm) could be excited over a wide wavelength range in the NIR region. During the release process of IBU in simulated body fluid (SBF), along with the dissolving of the drug, the solvent entered into the pores, and the emission intensity of the YAG:Nd(3+) fibers at 1064 nm decreased gradually, owing to a quenching effect of the hydroxy groups, thus provided an approach to track and monitor drug release. In addition, cytotoxicity investigations revealed that these YAG:Nd(3+) fibers were biocompatible with human cells. Consequently, the porous YAG:Nd(3+) fibers are a promising material for applications as advanced drug carriers. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Wang X.,Cornell University | Wang X.,South China University of Technology | Yun J.-W.,Cornell University | Lei X.G.,Cornell University
Antioxidants and Redox Signaling | Year: 2014

Aims: Glutathione peroxidase (GPX) mimic ebselen and superoxide dismutase (SOD) mimic copper diisopropylsalicylate (CuDIPs) were used to rescue impaired glucose-stimulated insulin secretion (GSIS) in islets of GPX1 and(or) SOD1-knockout mice. Results: Ebselen improved GSIS in islets of all four tested genotypes. The rescue in the GPX1 knockout resulted from a coordinated transcriptional regulation of four key GSIS regulators and was mediated by the peroxisome proliferator-Activated receptor gamma coactivator 1 alpha (PGC-1α)-mediated signaling pathways. In contrast, CuDIPs improved GSIS only in the SOD1 knockout and suppressed gene expression of the PGC-1α pathway. Innovation: Islets from the GPX1 and(or) SOD1 knockout mice provided metabolically controlled intracellular hydrogen peroxide (H2O 2) and superoxide conditions for the present study to avoid confounding effects. Bioinformatics analyses of gene promoters and expression profiles guided the search for upstream signaling pathways to link the ebselen-initiated H2O2 scavenging to downstream key events of GSIS. The RNA interference was applied to prove PGC-1α as the main mediator for that link. Conclusion: Our study revealed a novel metabolic use and clinical potential of ebselen in rescuing GSIS in the GPX1-deficient islets and mice, along with distinct differences between the GPX and SOD mimics in this regard. These findings highlight the necessities and opportunities of discretional applications of various antioxidant enzyme mimics in treating insulin secretion disorders. Rebound Track: This work was rejected during standard peer review and rescued by Rebound Peer Review (Antioxid Redox Signal 16: 293-296, 2012) with the following serving as open reviewers: Regina Brigelius-Flohe, Vadim Gladyshev, Dexing Hou, and Holger Steinbrenner. Antioxid. Redox Signal. 20, 191-203. © Copyright 2014, Mary Ann Liebert, Inc. 2014.

You K.,Nanyang Technological University | Su W.,South China University of Technology | Fu M.,Zhejiang University | Xie L.,Nanyang Technological University
Automatica | Year: 2011

This paper investigates the attainability of the minimum average data rate for stabilization of linear systems via logarithmic quantization. It is shown that a finite-level logarithmic quantizer suffices to approach the well-known minimum average data rate for stabilizing an unstable linear discrete-time system under two basic network configurations. In particular, we derive explicit finite-level logarithmic quantizers and the corresponding controllers to approach the minimum average data rate. © 2010 Published by Elsevier Ltd.

Gu G.-Y.,Shanghai JiaoTong University | Zhu L.-M.,Shanghai JiaoTong University | Su C.-Y.,South China University of Technology | Su C.-Y.,Concordia University at Montreal | Ding H.,Shanghai JiaoTong University
IEEE/ASME Transactions on Mechatronics | Year: 2013

In this paper, a general skeleton on modeling, controller design, and applications of the piezoelectric positioning stages is presented. Toward this framework, a general model is first proposed to characterize dynamic behaviors of the stage, including frequency response of the stage, voltage-charge hysteresis and nonlinear electric behavior. To illustrate the validity of the proposed general model, a dynamic backlash-like model is adopted as one of hysteresis models to describe the hysteresis effect, which is confirmed by experimental tests. Thus, the developed model provides a general frame for controller design. As an illustration to this aspect, a robust adaptive controller is developed based on a reduced dynamic model under both unknown hysteresis nonlinearities and parameter uncertainties. The proposed control law ensures the boundedness of the closed-loop signals and desired tracking precision. Finally, experimental tests with different motion trajectories are conducted to verify the proposed general model and the robust control law. Experimental results demonstrate the excellent tracking performance, which validates the feasibility and effectiveness of the proposed approach. © 1996-2012 IEEE.

Wang M.,South China University of Technology | Liu X.,Lakehead University | Shi P.,University of South Wales | Shi P.,Victoria University of Melbourne
IEEE Transactions on Systems, Man, and Cybernetics, Part B: Cybernetics | Year: 2011

This paper is concerned with robust stabilization problem for a class of nonaffine pure-feedback systems with unknown time-delay functions and perturbed uncertainties. Novel continuous packaged functions are introduced in advance to remove unknown nonlinear terms deduced from perturbed uncertainties and unknown time-delay functions, which avoids the functions with control law to be approximated by radial basis function (RBF) neural networks. This technique combining implicit function and mean value theorems overcomes the difficulty in controlling the nonaffine pure-feedback systems. Dynamic surface control (DSC) is used to avoid the explosion of complexity in the backstepping design. Design difficulties from unknown time-delay functions are overcome using the function separation technique, the Lyapunov-Krasovskii functionals, and the desirable property of hyperbolic tangent functions. RBF neural networks are employed to approximate desired virtual controls and desired practical control. Under the proposed adaptive neural DSC, the number of adaptive parameters required is reduced significantly, and semiglobal uniform ultimate boundedness of all of the signals in the closed-loop system is guaranteed. Simulation studies are given to demonstrate the effectiveness of the proposed design scheme. © 2006 IEEE.

Zhang H.,South China University of Technology
AIP Advances | Year: 2013

A phenomenological theory has been proposed for the diffusionless structural phase transitions in BaTiO3 single crystal and PbZrO 3 -xPbTiO3 solid solution here. It has been found that for BaTiO3 single crystal, both the phase transitions and the crystal structures can be predicted with the crystalline anisotropy constants and strain constants that depend on the temperature. For PbZrO3 -xPbTiO 3 solution, the morphotropic phase boundaries arise from the strong dependence of the crystalline anisotropy constants on the composition. The good agreement between the numerical results and experimental observations has shown that our theory is effective for the diffusionless structural phase transitions. © 2013 © 2013 Author(s).

Yang X.,South China University of Technology | Yang X.,University of Technology, Sydney | Zhang G.,University of Technology, Sydney | Lu J.,University of Technology, Sydney | Ma J.,University of Technology, Sydney
IEEE Transactions on Fuzzy Systems | Year: 2011

The support vector machine (SVM) has provided higher performance than traditional learning machines and has been widely applied in real-world classification problems and nonlinear function estimation problems. Unfortunately, the training process of the SVM is sensitive to the outliers or noises in the training set. In this paper, a common misunderstanding of Gaussian-function-based kernel fuzzy clustering is corrected, and a kernel fuzzy c-means clustering-based fuzzy SVM algorithm (KFCM-FSVM) is developed to deal with the classification problems with outliers or noises. In the KFCM-FSVM algorithm, we first use the FCM clustering to cluster each of two classes from the training set in the high-dimensional feature space. The farthest pair of clusters, where one cluster comes from the positive class and the other from the negative class, is then searched and forms one new training set with membership degrees. Finally, we adopt FSVM to induce the final classification results on this new training set. The computational complexity of the KFCM-FSVM algorithm is analyzed. A set of experiments is conducted on six benchmarking datasets and four artificial datasets for testing the generalization performance of the KFCM-FSVM algorithm. The results indicate that the KFCM-FSVM algorithm is robust for classification problems with outliers or noises. © 2006 IEEE.

Liang J.-Z.,South China University of Technology
Polymer Bulletin | Year: 2011

The correlation between the entry pressure drop and elongation viscosity during entry converging flow of polymer melts was discussed in this article. The entry pressure drop during extrusion of a low density polyethylene (LDPE) melt and a linear low density polyethylene (LLDPE) melt was measured by means of a capillary rheometer under test conditions with temperature of 170 °C and shear rate varying from 10 to 300 s -1. The results showed that the entry pressure drop increased nonlinearly with an increase of the shear stain rate, and the variation of entry pressure drop of the two melts was close to each other. The melt elongation viscosity of the two resins was estimated using Cogswell equation from the measured entry pressure drop data, and the predictions were compared with the melt extension viscosity measured by using a melt spinning technique published in literature. It was found that the melt extension viscosity from entry converging flow was slightly lower than that from melt spinning technique under the same temperature and extension strain rate. © Springer-Verlag 2011.

Wan J.,South China University of Technology | Jones J.D.,Liberty University
Enterprise Information Systems | Year: 2013

The Warfield version of systems science supports a wide variety of application areas, and is useful to practitioners who use the work program of complexity (WPOC) tool. In this article, WPOC is applied to information technology service management (ITSM) for managing the complexity of projects. In discussing the application of WPOC to ITSM, we discuss several steps of WPOC. The discovery step of WPOC consists of a description process and a diagnosis process. During the description process, 52 risk factors are identified, which are then narrowed to 20 key risk factors. All of this is done by interviews and surveys. Root risk factors (the most basic risk factors) consist of 11 kinds of common 'mindbugs' which are selected from an interpretive structural model. This is achieved by empirical analysis of 25 kinds of mindbugs. (A lesser aim of this research is to affirm that these mindbugs developed from a Western mindset have corresponding relevance in a completely different culture: the Peoples Republic of China.) During the diagnosis process, the relationships among the root risk factors in the implementation of the ITSM project are identified. The resolution step of WPOC consists of a design process and an implementation process. During the design process, issues related to the ITSM application are compared to both e-Government operation and maintenance, and software process improvement. The ITSM knowledge support structure is also designed at this time. During the implementation process, 10 keys to the successful implementation of ITSM projects are identified. © 2013 Copyright Taylor and Francis Group, LLC.

Liang J.-Z.,South China University of Technology
Polymer Composites | Year: 2011

The parameters characterizing the interfacial adhesion strength, such as interaction parameter (B) and interfacial adhesion angle (θ), of inorganic particulate-filled polymer composites were analyzed in this paper. On the basis of the previous studies and the research work reported in literature, several expressions for predicting these parameters and the determination methods of these parameters were proposed, and the relationship between the interaction parameter and interfacial adhesion angle was discussed. Then the parameters B and θ were estimated from the experimental measured tensile strength of the several inorganic particulate-filled polypropylene (PP) composites including nanometer calcium carbonate, glass bead and diatomite particles. The results showed that the value of θ was about from 44 to 75 degrees while the value of B was varying from 1.12 to 2.42 of these filled systems under the experimental conditions. Moreover, the value of B decreased roughly linearly with increasing θ for these particulate-filled PP composites. © 2011 Society of Plastics Engineers.

Oudich M.,CNRS Jean Lamour Institute | Assouar M.B.,CNRS Jean Lamour Institute | Hou Z.,South China University of Technology
Applied Physics Letters | Year: 2010

We demonstrate the waveguiding of Lamb waves in a locally resonant phononic crystal (LRPC) and we present an analysis of the guiding of elastic waves in straight and bent waveguides. The finite element method combined with the supercell technique was used to analyze the band gap and the dispersion relation of LRPC waveguides. Unlike the traditional phononic crystals, we show the possibility of guiding only one confined mode inside a LRPC waveguide. We discuss the confinement and the transmission of the guided mode as a function of the width of the waveguide based on both the band structure and the displacement field. © 2010 American Institute of Physics.

Hou Z.,South China University of Technology | Assouar B.M.,CNRS Jean Lamour Institute
Applied Physics Letters | Year: 2015

We report in this letter on a tunable solid acoustic metamaterial with negative elastic modulus by means of piezoelectric composite. The theoretical formulae for one-dimensional layer-stacked metamaterial embedding a piezoelectric material by means of external shunted inductors are presented. The acoustic band structure of the composite is calculated by the transfer matrix method. Results show that a band gap can be opened and tuned by the resonant behavior of the LC circuit. It is found further by the formulae that piezoelectric material with large piezoelectric constant and small elastic modulus will be beneficial for opening a wide band gap. The effective elastic constant of the system is also calculated by the unit-cell-boundary-averaging method. Result shows that the system behaves as an effective medium with a negative elastic modulus. This property is quite different from the typical solid metamaterial achieved by dispersing heavy inclusions coated with a soft layer into a matrix for which only the negative mass density can be obtained. © 2015 AIP Publishing LLC.

Qin C.,South China University of Technology
Wei sheng wu xue bao = Acta microbiologica Sinica | Year: 2012

It is a conserved mechanism in bacteria that metalloprotease site-2 protease (S2P) cleaves transmembrane anti-sigma factor to release sequestered sigma factor in response to extracytoplasmic stress. However, the function of site-2 protease homologs in cyanobacteria remains elusive, so we investigated the metalloprotease activity of Slr0643 and Sll0862, the site-2 protease homologs from Synechocystis sp. PCC6803. Recombinant Slr0643 and Sll0862 were constructed and overexpressed in Escherichia coli BL21 (CE3). Their protease activities were tested against beta-casein and then resolved on SDS-PAGE. Results from caseinolytic assay indicated that Slr0643 and Sll0862 have proteolytic activity which is blocked by o-phenanthroline, a metalloprotease inhibitor. These metalloprotease activity of Slr0643 and Sll0862 in vitro provide the foundation for futher analysis of their substrates in vivo. The site-2 protease homologs in Synechocystis sp. PCC6803 have metalloprotease activity.

Liu Z.,South China University of Technology | Wen F.,Zhejiang University | Wen F.,Queensland University of Technology | Ledwich G.,Queensland University of Technology
IEEE Transactions on Power Delivery | Year: 2013

With the progressive exhaustion of fossil energy and the enhanced awareness of environmental protection, more attention is being paid to electric vehicles (EVs). Inappropriate siting and sizing of EV charging stations could have negative effects on the development of EVs, the layout of the city traffic network, and the convenience of EVs' drivers, and lead to an increase in network losses and a degradation in voltage profiles at some nodes. Given this background, the optimal sites of EV charging stations are first identified by a two-step screening method with environmental factors and service radius of EV charging stations considered. Then, a mathematical model for the optimal sizing of EV charging stations is developed with the minimization of total cost associated with EV charging stations to be planned as the objective function and solved by a modified primal-dual interior point algorithm (MPDIPA). Finally, simulation results of the IEEE 123-node test feeder have demonstrated that the developed model and method cannot only attain the reasonable planning scheme of EV charging stations, but also reduce the network loss and improve the voltage profile. © 1986-2012 IEEE.

Liang J.-Z.,South China University of Technology
Journal of Polymers and the Environment | Year: 2016

The tensile and combustion properties of polypropylene/polyolyaltha olefin composites filled with intumescent flame retardant (IFR) and nanometer calcium carbonate (nano-CaCO3) were measured. It was found that the values of the Young’s modulus of the composites increased almost linearly, while the values of the tensile yield strength and tensile fracture strength of the composites decreased with increasing the IFR weight fraction; the values of the elongation at break of the composites decreased quickly when the IFR weight fraction was lower than 10 wt%, and then varied slightly when the IFR weight fraction was higher than 10 wt%. Moreover, the morphology of the specimens after combustion was observed and the frame retardant mechanisms of the composites were discussed. © 2016 Springer Science+Business Media New York

Zhao J.,South China University of Technology | Hadjichristidis N.,King Abdullah University of Science and Technology
Polymer Chemistry | Year: 2015

Organocatalytic ring-opening polymerization (ROP) reactions of three renewable 5-alkyl δ-lactones, namely δ-hexalactone (HL), δ-nonalactone (NL) and δ-decalactone (DL), using diphenyl phosphate (DPP) were investigated. Room temperature, together with a relatively high monomer concentration (≥3 M), was demonstrated to be suitable for achieving a living ROP behavior, a high conversion of the lactone, a controlled molecular weight and a low dispersity of the polyester. HL, containing a 5-methyl substituent, showed a much higher reactivity (polymerization rate) and a slightly higher equilibrium conversion than the compounds with longer alkyl substituents (NL and DL). The effectiveness of DPP-catalyzed ROP of 5-alkyl δ-lactones facilitated the one-pot performance following the t-BuP4-promoted ROP of monosubstituted epoxides. It has been shown in an earlier study that substituted polyethers acted as "slow initiators" for non-substituted lactones. However, efficient initiations were observed in the present study as substituted lactones were polymerized from the substituted polyethers. Therefore, this reinforces the previously developed "catalyst switch" strategy, making it a more versatile tool for the synthesis of well-defined polyether-polyester block copolymers from a large variety of epoxide and lactone monomers. © The Royal Society of Chemistry 2015.

Xiao J.,South China University of Technology | Sitamraju S.,Pennsylvania State University | Janik M.J.,Pennsylvania State University
Langmuir | Year: 2014

This work examines CO2 adsorption over various N-substituted/grafted graphanes to identify the promotional effects of various N-functionalities have on the adsorption characteristics using DFT. CO 2 adsorbs weakly on a graphane surface functionalized with a single, isolated substituted N- or grafted NH2-sites. The presence of coadsorbed H2O on the surface promotes CO2 adsorption on both N- and NH2-sites, with highly exothermic adsorption energies (∼-50 kJ mol-1). Directly grafted -NH2 or -OH functional groups on C atoms adjacent to C atoms which have a -NH2 group grafted suffer from geometrical restrictions preventing dual stabilization of formed carbamate upon adsorption of CO2. CO2 adsorption can be greatly enhanced with the presence of a -OH group or second -NH2 group in the proximity of a -NH2 site on graphane, and only if a n(-CH2-) (n ≥ 1) linker is introduced between the -NH2 or -OH and graphane surface (adsorption energies of -58.8 or -43.1 kJ mol-1 at n = 2). The adsorption mechanistics provided by DFT can be used to guide the atomic-level rational design of N-based graphane and carbon adsorbents for CO2 capture. © 2014 American Chemical Society.

Yang J.,University of Wisconsin - Madison | Zhang W.-D.,South China University of Technology | Gunasekaran S.,University of Wisconsin - Madison
Biosensors and Bioelectronics | Year: 2010

A non-enzymatic glucose (Glc) sensor was developed by potentiostatically electrodepositing metallic Cu nanocubes from a precursor solution onto vertically well-aligned multi-walled carbon nanotube arrays (MWCNTs). The electrochemical characteristics of the sensor were studied by electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV). The sensor shows significantly higher electrocatalytic activity to the oxidation of Glc in 0.1M NaOH alkaline solution after modification of Cu nanocubes than before. The sensor response is rapid (<1s) and highly sensitive (1096μAmM-1cm-2) with a wide linear range (up to 7.5mM) and low detection limit (1.0μM at signal/noise ratio (S/N)=3); it also exhibits high stability and specificity to Glc and performs very well in detecting of Glc concentration in human blood serum. © 2010 Elsevier B.V.

He S.,Southern Medical University | Liu S.,South China University of Technology | Zhu H.,Southern Medical University
BMC Evolutionary Biology | Year: 2011

Background: An increasing number of long noncoding RNAs (lncRNAs) have been identified recently. Different from all the others that function in cis to regulate local gene expression, the newly identified HOTAIR is located between HoxC11 and HoxC12 in the human genome and regulates HoxD expression in multiple tissues. Like the well-characterised lncRNA Xist, HOTAIR binds to polycomb proteins to methylate histones at multiple HoxD loci, but unlike Xist, many details of its structure and function, as well as the trans regulation, remain unclear. Moreover, HOTAIR is involved in the aberrant regulation of gene expression in cancer. Results: To identify conserved domains in HOTAIR and study the phylogenetic distribution of this lncRNA, we searched the genomes of 10 mammalian and 3 non-mammalian vertebrates for matches to its 6 exons and the two conserved domains within the 1800 bp exon6 using Infernal. There was just one high-scoring hit for each mammal, but many low-scoring hits were found in both mammals and non-mammalian vertebrates. These hits and their flanking genes in four placental mammals and platypus were examined to determine whether HOTAIR contained elements shared by other lncRNAs. Several of the hits were within unknown transcripts or ncRNAs, many were within introns of, or antisense to, protein-coding genes, and conservation of the flanking genes was observed only between human and chimpanzee. Phylogenetic analysis revealed discrete evolutionary dynamics for orthologous sequences of HOTAIR exons. Exon1 at the 5' end and a domain in exon6 near the 3' end, which contain domains that bind to multiple proteins, have evolved faster in primates than in other mammals. Structures were predicted for exon1, two domains of exon6 and the full HOTAIR sequence. The sequence and structure of two fragments, in exon1 and the domain B of exon6 respectively, were identified to robustly occur in predicted structures of exon1, domain B of exon6 and the full HOTAIR in mammals. Conclusions: HOTAIR exists in mammals, has poorly conserved sequences and considerably conserved structures, and has evolved faster than nearby HoxC genes. Exons of HOTAIR show distinct evolutionary features, and a 239 bp domain in the 1804 bp exon6 is especially conserved. These features, together with the absence of some exons and sequences in mouse, rat and kangaroo, suggest ab initio generation of HOTAIR in marsupials. Structure prediction identifies two fragments in the 5' end exon1 and the 3' end domain B of exon6, with sequence and structure invariably occurring in various predicted structures of exon1, the domain B of exon6 and the full HOTAIR. © 2011 He et al; licensee BioMed Central Ltd.

Gan L.-Y.,King Abdullah University of Science and Technology | Zhao Y.-J.,South China University of Technology | Huang D.,University of Science and Arts of Iran | Schwingenschlogl U.,King Abdullah University of Science and Technology
Physical Review B - Condensed Matter and Materials Physics | Year: 2013

First-principles calculations are used to explore the geometry, bonding, and electronic properties of MoS2/Ti2C and MoS 2/Ti2CY2 (Y = F and OH) semiconductor/metal contacts. The structure of the interfaces is determined. Strong chemical bonds formed at the MoS2/Ti2C interface result in additional states next to the Fermi level, which extend over the three atomic layers of MoS2 and induce a metallic character. The interaction in MoS 2/Ti2CY2, on the other hand, is weak and not sensitive to the specific geometry, and the semiconducting nature thus is preserved. The energy level alignment implies weak and strong n-type doping of MoS2 in MoS2/Ti2CF2 and MoS 2/Ti2C(OH)2, respectively. The corresponding n-type Schottky barrier heights are 0.85 and 0.26 eV. We show that the MoS 2/Ti2CF2 interface is close to the Schottky limit. At the MoS2/Ti2C(OH)2 interface, we find that a strong dipole due to charge rearrangement induces the Schottky barrier. The present interfaces are well suited for application in all-two-dimensional devices. © 2013 American Physical Society.

Zhao Z.,Hangzhou Normal University | Lam J.W.Y.,Hong Kong University of Science and Technology | Tang B.Z.,Hong Kong University of Science and Technology | Tang B.Z.,South China University of Technology
Soft Matter | Year: 2013

Fluorescent self-assembled organogels are interesting supramolecular soft materials with polymer-like structures and have received particular attention due to their fascinating properties and promising practical applications. However, most planar π-conjugated gelators are highly emissive in the solution state but become weak emitters when self-assembled. Recently, a novel phenomenon of aggregation-induced emission (AIE) has drawn increasing research interest and has been the subject of numerous investigations. This intriguing finding paves a new way for creating fluorescent organogels by utilizing gelators with AIE characteristics. This review focuses on the recent advances in fluorescent organogels with gelation-enhanced emission features. Various kinds of low molecular weight gelators consisting of typical AIE luminogens, conventional planar chromophores, and photoactive molecules are introduced and the mechanisms for the emission enhancement are discussed. This journal is © 2013 The Royal Society of Chemistry.

Luo Y.,South China University of Technology | Luo Y.,Utah State University | Chen Y.,Utah State University
Automatica | Year: 2012

For all the stable first order plus time delay (FOPTD) systems, a fractional order proportional integral (FOPI) or a traditional integer order proportional integral derivative (IOPID) controller can be designed to fulfill a flat phase constraint and two design specifications simultaneously: gain crossover frequency and phase margin. In this paper, a guideline for choosing two feasible or achievable specifications, and a new FOPI/IOPID controller synthesis are proposed for all the stable FOPTD systems. Using this synthesis scheme, the complete feasible region of two specifications can be obtained and visualized in the plane. With this region as the prior knowledge, all combinations of two specifications can be verified before the controller design. Especially, it is interesting to compare the areas of these two feasible regions for the IOPID and FOPI controllers. This area comparison reveals, for the first time, the potential advantages of one controller over the other in terms of achievable performances. A simulation illustration is presented to show the effectiveness and the performance of the designed FOPI controller compared with the optimized integer order PI controller and the IOPID controller designed following the same synthesis for the FOPI in this paper. © 2012 Elsevier Ltd. All rights reserved.

Yuan Y.,National University of Singapore | Zhang C.-J.,National University of Singapore | Gao M.,Institute of Materials Research and Engineering of Singapore | Zhang R.,National University of Singapore | And 4 more authors.
Angewandte Chemie - International Edition | Year: 2015

Activatable photosensitizers (PSs) have been widely used for the simultaneous fluorescence imaging and photodynamic ablation of cancer cells. However, the ready aggregation of traditional PSs in aqueous media can lead to fluorescence quenching as well as reduced phototoxicity even in the activated form. We have developed a series of PSs that show aggregation-enhanced emission and phototoxicity and thus the exact opposite behavior to that of previously reported PSs. We further developed a dual-targeted enzyme-activatable bioprobe based on the optimized photosensitizer and describe simultaneous light-up fluorescence imaging and activated photodynamic therapy for specific cancer cells. The design of smart probes should thus open new opportunities for targeted and image-guided photodynamic therapy. © 2015 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Cheng J.,South China University of Technology
Physical Review A - Atomic, Molecular, and Optical Physics | Year: 2016

Inspired by the idea of ghost imaging, we propose a ghost scattering scheme to study light scattering with incoherent light sources through the nonlocal correlation measurement of the differential scattering cross-section fluctuations in two different optical paths. We present a rigorous formal theory to describe the ghost scattering process. Also we have derived a simple and closed-form ghost scattering formula within the first-order Born approximation which is particularly suited for weak scatterers. We find that the scattering information of a test scatterer can be obtained by using only a single-pixel detector in the corresponding optical path through the nonlocal correlation measurement with the help of another reference path. © 2016 American Physical Society.

Wang T.,South China University of Technology | Lin B.,Minjiang University | Lin B.,Xiamen University
Energy Policy | Year: 2014

China's natural gas consumption is growing rapidly and it has being driven by economic growth, industrialization and urbanization. In addition, the country's low-carbon development strategy, government-controlled gas price, and some other factors also contribute to the surging gas consumption. This paper studies China's natural gas consumption in residential, industrial and commercial sectors. We adopt the cointegration test and error correction model to study the relationships of explanatory factors and gas consumption of different sectors and climate factor is included into the analysis. In order to find the direction of natural gas pricing reform and establish the benchmark gas price, this paper also estimates the size of gas price subsidy by using price-gap approach. Our findings are as follows: In the long term, China's residential sector is more sensitive to price than the other two. Urbanization is an important factor promoting industrial and commercial gas consumption. Prices of other energies have an influence on natural gas consumption significantly due to the substitutability between energies. The slow-moving and unsatisfying pricing reforms on refined oil and natural gas lead to positive price elasticity of natural gas in the commercial sector, which implies that a further energy price reform is still stringent for China. © 2013 Elsevier Ltd.

Li T.,South China University of Technology | Guthrie J.T.,University of Leeds
Bioresource Technology | Year: 2010

The decoloration treatment of textile dye effluents through biodegradation, using bacterial cells, has been studied as a possible means of solving some of the problems that are associated with the pollution of water sources by colorants. In this paper, the use of whole bacterial cells of Shewanella J18 143 for the reduction of aqueous solutions of selected mono-azo, metal-complex dyes, namely Irgalan Grey GLN, Irgalan Black RBLN and Irgalan Blue 3GL, was investigated. The effects of temperature, pH and dye concentration on colour removal were also investigated and shown to be important. The operative conditions for the removal of colour were 30 °C, at pH 6.8, with a final dye concentration of 0.12 g/L in the colour reduction system. This study provides an extension to the application of Shewanella strain J18 143 bacterial cells in the decoloration of textile wastewaters. Crown Copyright © 2010.

Yang S.-Q.,University of Wollongong | Liu P.-W.,South China University of Technology
Journal of Great Lakes Research | Year: 2010

Taihu Lake, the third largest freshwater lake in China, is located in the Chanjiang Delta of the Yangtze River. Its waters are used by agriculture, industry and as major drinking water for several cities including Shanghai and Wuxi. The lake also is important for tourism, aquaculture and flood control. Taihu Lake and its surrounding areas are facing three major water-related threats: deteriorating water quality with inflow and runoff from its watershed; flooding during the rainy seasons; and water shortages during drier months. Noxious algae blooms are occurring with increasing frequency and water quality continues to decline. Remedial actions implemented to date have been ineffective. This paper proposes that the problems could be remedied by constructing a by-pass channel (BPC), which would divert low-quality water from the lake during low precipitation periods and allow better quality water to flow into the lake during high flow periods. This remedial action would simultaneously deal with the deteriorating water quality of Lake Taihu and maintain its water level at a desired level. A preliminary assessment of this strategy shows that, if the BPC were implemented, the water quality of Taihu Lake would be improved significantly in few years, the flood disaster would be greatly mitigated, and the water shortage problem in the basin would be alleviated. Crown Copyright © 2009.

Li H.,Nanjing Institute of Technology | Luo Y.,South China University of Technology | Chen Y.,Utah State University
IEEE Transactions on Control Systems Technology | Year: 2010

In recent years, it is remarkable to see the increasing number of studies related to the theory and application of fractional order controller (FOC), specially PIλDμ controller, in many areas of science and engineering. Research activities are focused on developing new analysis and design methods for fractional order controllers as an extension of classical control theory. In this paper, a new tuning method for fractional order proportional and derivative (PD;mu; or FO-PD controller is proposed for a class of typical second-order plants. The tuned FO-PD controller can ensure that the given gain crossover frequency and phase margin are fulfilled, and furthermore, the phase derivative w. r. t. the frequency is zero, i.e., the phase Bode plot is flat at the given gain crossover frequency. Consequently, the closed-loop system is robust to gain variations. The FOC design method proposed in the paper is practical and simple to apply. Simulation and experimental results show that the closed-loop system can achieve favorable dynamic performance and robustness. © 2009 IEEE.

Chen K.,Nanjing University of Aeronautics and Astronautics | Yang L.,South China University of Technology
International Journal of Production Research | Year: 2014

This paper considers a supply chain in which a buyer purchases finished items from a contracting supplier to satisfy a stochastic market demand, where the suppliers production is subject to random yield. We assume that the buyer can make up the shortage by sourcing from an emergency backup supplier. We develop two Stackelberg game models, i.e. buyer-Stackelberg (BS) model and supplier-Stackelberg (SS) model, and find that the decentralised BS model results in a higher stocking factor of suppliers input than the decentralised SS model. Compared with BS model, the buyer in SS model performs more explicit order plan, and we find that only when the actual yield of the supplier is insufficient, the buyer would use emergency backup sourcing to make up the shortage. When the manufacturing operation of the supplier is in the good state, the buyer only orders a certain amount and has some leftover. When the actual yield of the supplier is moderate, the buyer uses up every item produced from the supplier regardless of the yield rate. Comparing both channel structures, SS operation is a more effective way of controlling both inventory cost and backup sourcing cost, and it can be beneficial for each player as well as for the whole channel. Finally, we develop the coordination mechanism for each channel to investigate the issues of risk handling and risk sharing for uncertain demand and uncertain yield. © 2014 Taylor & Francis.

Yang L.,Institute for Integrative Nanosciences | Yang L.,South China University of Technology | Wang S.,Fudan University | Mao J.,Fudan University | And 6 more authors.
Advanced Materials | Year: 2013

Hierarchical MoS2/polyaniline nanowires, integrating MoS 2 nanosheets with conductive polyaniline, serve as prominent anode materials for Li-ion batteries, presenting high capacity and good cyclability. The polyaniline-hybrid structure and hierarchical features significantly promote the Li-storage performance as compared with the bare MoS2, indicating new opportunities for developing electrode nanomaterials. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Gong X.,South China University of Technology | Wang Z.,Chinese University of Hong Kong | Ngai T.,Chinese University of Hong Kong
Chemical Communications | Year: 2014

Non-covalent intermolecular forces, such as van der Waals, electrostatic, steric, and hydrophobic interactions, have played essential roles in determining the association, aggregation, adhesion and sedimentation processes of colloidal particles, surfactant micelles, and macromolecules, in solutions and biological systems. These interaction forces, however, are normally weak (

Meier H.,University of Mainz | Cao D.,South China University of Technology
Chemical Society Reviews | Year: 2013

The dimerization of anthracene by a [4π + 4π] cycloaddition is one of the oldest and best known reactions in photochemistry. In the series of tethered bichromophoric arenes, this reaction type could be extended to anthracene-naphthalene, naphthalene-naphthalene and recently even to anthracene-benzene and naphthalene-benzene systems. Cyclophanes, which can be regarded as twofold or multiple tethered systems, are not discussed here. The cycloisomerizations are performed by irradiation at the long-wavelength absorption (λ > 270 nm), whereas shorter wavelengths (λ < 270 nm) lead to cycloreversions, which can be also achieved by a thermal route. The systems represent therefore a P- and T-type photochromism, which can be used for optical or chiroptical switches. An acceleration of the switch is possible by a singlet energy transfer (light harvesting antenna effect) in dendritic compounds. In the past 5 to 10 years many applications of these switches were studied in the context of photonic devices, sensor techniques, lithographic processes, imaging techniques, data processing and data storage.

Zhan H.-Y.,South China University of Technology
Chung-kuo Tsao Chih/China Pulp and Paper | Year: 2010

Non-wood fibers and waste papers are the important fiber raw materials in China's paper industry. In this paper, the resources and utilization of non-wood fiber species, including bamboo, wheat straw, bagasse and reed, as well as waste papers in China's paper industry are introduced. The technological progresses in non-wood fiber and waste paper pulping and papermaking are reviewed.

Zhang L.-Z.,South China University of Technology
Journal of Membrane Science | Year: 2010

Hollow fiber membrane modules have been employed for heat and moisture recovery from ventilation air. There are several benefits with this structure. The contact area is large. The resulting NTU (Number of Transfer Units) is high, which implicates a high performance. In this research, the governing equations for heat and moisture transfer in the module are proposed. The equations are then normalized with dimensionless parameters. Following this step, an analytical solution is obtained for the dimensionless differential governing equations. With the developed analytical solution, the sensible and latent heat exchange effectiveness could be estimated by simple algebraic calculations. This provides a convenient yet accurate tool for component design and system optimization. Experiments are conducted to validate the model. Effects of varying operating conditions on module performances are discussed. The study provides a tool for hollow fiber module optimization with simple correlations. © 2010 Elsevier B.V.

Zhu H.,South China University of Technology
Advances in Information Sciences and Service Sciences | Year: 2012

This article chooses from 2008 to the end of 2009 in the Shenzhen Stock Exchange listing on the gem IPO company internal control information that disclosure is perfect and the corresponding IPO underpricing, through the information transmission model, empirical analysis of IPO, underpricing of IPO internal control information disclosure responses, and a comparison of the same period, small and medium-sized board and main board gem underpricing rate of different influence factors, to find out the advantages and characteristics of gem. Conclusion the gem IPO underpricing rate on the internal control information disclosure consummation or not have significant response, therefore to realize the effective configuration of venture capital venture capital market in China, to solve the problem of information transparency from the venture capital market perfect, organization of venture capital investment and the construction of the government service function and regulatory functions of the perfect three aspects, further consummates our country does pioneering work board the market.

Zhang X.,South China University of Technology
Physical Review D - Particles, Fields, Gravitation and Cosmology | Year: 2014

As a first step to generalize the structure of loop quantum cosmology to the theories with the spacetime dimension other than four, the isotropic model of loop quantum cosmology in 2+1 dimension is studied in this paper. We find that the classical big bang singularity is again replaced by a quantum bounce in the model. The similarities and differences between the (2+1)-dimensional model and the (3+1)-dimensional one are also discussed. © 2014 American Physical Society.

Zhao L.-C.,Northwest University, China | Ling L.,South China University of Technology
Journal of the Optical Society of America B: Optical Physics | Year: 2016

We study the relations between modulational instability and several well-known nonlinear excitations in a nonlinear fiber such as bright soliton, nonlinear continuous wave, Akhmediev breather, Peregrine rogue wave, and Kuznetsov-Ma breather. We present a quantitative correspondence between them based on the dominant frequency and propagation constant of each perturbation on a continuous-wave background. We especially demonstrate that rogue wave comes from modulational instability with the resonance perturbation on continuouswave background. The numerical simulations are performed to test these theoretical results. These results will deepen our understanding of rogue wave excitation and be helpful for controllable nonlinear wave excitations in nonlinear fiber and other nonlinear systems. © 2016 Optical Society of America.

Zhu R.,South China University of Technology
Journal of Physics Condensed Matter | Year: 2013

Fano resonance appears for conduction through an electron waveguide containing donor impurities. In this work, we consider the thin-film conducting chiral helimagnet (CCH) as the donor impurity in a one-dimensional waveguide model. The transmission and conductance for an arbitrary CCH spiral period are obtained. Due to the spin-spiral coupling, interference between the direct and inter-subband transmission channels gives rise to a spin-dependent Fano resonance effect. The spin-dependent Fano resonance is sensitively dependent on the helicity of the spiral. By tuning the CCH potential well depth and the incident energy, this provides a potential way to detect the spin-spiral period in the CCH. © 2013 IOP Publishing Ltd.

Wu F.,Shantou University | Zhang X.,South China University of Technology
Robotics and Computer-Integrated Manufacturing | Year: 2014

In order to improve the comprehensive performance of solder joints inspection in three aspects, i.e. high recognition rate, detailed classification of defect types and fast inspection speed, a new detection and classification algorithm of the chip solder joints based on color grads and Boolean rules is developed in this paper. Firstly, the region features, evaluation features and color grads' features are defined and extracted based on the special solder joint image, which is acquired by a particular image acquisition system composed of a 3-CCD color digital camera and a 3-color (red, green, and blue) hemispherical LED array illumination. Secondly, the models of solder joint types are built based on extracted features and statistical characteristics of solder joint types. Thirdly, the detection and classification method is designed and presented using Boolean rules, then eight common solder joint types, including the acceptable solder joint, pseudo, no solder, lacked solder, excess solder, shifted, tombstone, and miss component, can be classified and detected by the proposed algorithm. Fourthly, the proposed algorithm is optimized to improve the inspection speed based on a parallel computing method. Finally, to evaluate the performance of the proposed method, 79 pieces of PCBs with defects were inspected by the commercial AOI system developed by the authors which integrates the proposed algorithm. Experiment and result analysis illustrates that the proposed method is better than other methods in three aspects, it can detect and classify properly all the eight common types of solder joints, its detailed classification, and high correct rate, which is up to 97.7%, are more useful to the quality control in the manufacturing process, and its inspection speed is faster, thus helping us to improve the efficiency of the manufacturing process. © 2014 Published by Elsevier Ltd. All rights reserved.

Al-Saidi W.A.,University of Pittsburgh | Feng H.,Pennsylvania State University | Feng H.,South China University of Technology | Fichthorn K.A.,Pennsylvania State University
Nano Letters | Year: 2012

We use density functional theory to resolve the role of polyvinylpyrrolidone (PVP) in the shape-selective synthesis of Ag nanostructures. At the segment level, PVP binds more strongly to Ag(100) than Ag(111) because of a surface-sensitive balance between direct binding and van der Waals attraction. At the chain level, correlated segment binding leads to a strong preference for PVP bind to Ag(100). Our study underscores differences between small-molecule and polymeric structure-directing agents. © 2011 American Chemical Society.

Xu J.,Northeast Normal University | Jing N.,South China University of Technology
Journal of Hazardous Materials | Year: 2012

In this study relative condition factor (RCF) and hepatosomatic index (HSI) as well as the available energy reserves of common carp (Cyprinus carpio) by 2,4-DNT semi-static bioassay were determined and linked to effects of enzymes in liver tissues. Fish were exposed at sublethal concentrations of 2,4-DNT (0.13μg/L, 0.1, 0.5, 1.0mg/L) for 7 and 15d. Based on the results, there was no significant change in all parameters measured in fish exposed to 2,4-DNT at environmental related concentration, but 2,4-DNT stress in fish exposed to higher concentrations reflected the significant changes of physiological and biochemical responses. 2,4-DNT stress resulted in EROD activity induction in the liver, and the levels of EROD activity ranged from 0.39- to 1.83-fold higher than control. For GK, Na +/K +-ATPase, and GST, these enzyme activity continued to decline after exposure to 0.1, 0.5 and 1.0mg/L 2,4-DNT, whereas the trend on GK and Na +/K +-ATPase was more obvious than GST. Through principal component analysis, effects by 2,4-DNT-stress in each test group were distinguished. Additionally, indications of a trade-off between metabolic cost of toxicant exposure and processes vital to the survival of the organism were seen at the enzyme activity level as well as on higher levels of biological organization. © 2012 Elsevier B.V.

Luo H.,Leibniz University of Hanover | Efimov K.,Leibniz University of Hanover | Jiang H.,Leibniz University of Hanover | Feldhoff A.,Leibniz University of Hanover | And 2 more authors.
Angewandte Chemie - International Edition | Year: 2011

Cleaning up their act: A novel CO2-stable and cobalt-free dual-phase membrane for oxygen separation from air has been developed that consists of 40 wt % NiFe2O4 and 60 wt % Ce 0.9Gd0.1O2-δ. This membrane shows a steady oxygen permeation flux over 100 h using CO2 as sweep gas at 1000 °C. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Su S.-J.,South China University of Technology | Su S.-J.,Yamagata University | Cai C.,Yamagata University | Kido J.,Yamagata University
Chemistry of Materials | Year: 2011

A series of host materials 1 - 7 containing various heterocyclic cores, like pyridine, pyrimidine, and pyrazine, were developed for RGB phosphorescent organic light-emitting diodes (OLEDs). Their energy levels can be tuned by the change of heterocyclic cores and their nitrogen atom orientations, and decrease of singlet - triplet exchange energy (ΔEST) was achieved with introducing one or two nitrogen atoms into the central arylene; this is also consistent with density functional theory calculations. Their carrier mobilities can also be tuned by the choice of heterocyclic cores, giving improved bipolarity compared with that without any heterocyclic cores. Due to the high triplet energy level of the developed host materials, well confinement of triplet excitons of blue emitter iridium(III) bis(4,6-(difluorophenyl) pyridinato-N,C2′) picolinate (FIrpic) was achieved except for 7 due to its low ET. In contrast, triplet energy can be well confined on green emitter fac-tris(2-phenylpyridine) iridium (Ir(PPy)3) and red emitter tris(1-phenylisoquinolinolato-C2,N)iridium(III) (Ir(piq)3) for all the hosts, giving comparable lifetime (τ), photoluminescent quantum efficiency (ηPL), and radiative and nonradiative rate constants (kr and knr). Highly efficient blue and green phosphorescent OLEDs were achieved for 2, exhibiting one of the highest ever efficiencies to date, especially at much brighter luminance for lighting applications. In comparison, the highest efficiencies hitherto were achieved for the red phosphorescent OLED based on 6, which can be attributed to its lower-lying LUMO level and the smallest ΔEST, giving improved electron injection and carrier balance. Different from the blue and green phosphorescent OLEDs based on FIrpic and Ir(PPy)3, the host materials with lower-lying LUMO levels seem to be better hosts for a red emitter Ir(piq)3, achieving improved efficiency and reduced efficiency roll-off at high current density. © 2010 American Chemical Society.

Wang N.F.,South China University of Technology | Tai K.,Nanyang Technological University
Computers and Structures | Year: 2010

In multiobjective design optimization problems, the designer may know that some objectives are harder to extremize than others or that some regions of the objective space are more desirable/important. Such useful information can be incorporated into the genetic algorithm optimization procedure by treating the more challenging/important objectives as constraints whose ideal values are adaptively improved/tightened during the procedure to guide the search. Employing this adaptive constraint strategy and a morphological representation of geometric variables, a genetic algorithm was developed and evaluated through special 'Target Matching' test problems which are simulated topology/shape optimization problems with multiple objectives and constraints. © 2010 Published by Elsevier Ltd. All rights reserved.

Tian H.,Beijing Technology and Business University | Tian H.,South China University of Technology
Journal of Composite Materials | Year: 2012

Nanocomposite materials were prepared via glycerol plasticized soy protein as the matrix and in situ fabricated silica as thereinforcing phase. The silica nanoparticles were synthesized in the protein environment by sodium silicate as a precursor. The resulting composites were characterized by Fourier transform infrared spectroscopy (FTIR), wide-angle X-ray diffraction (WAXD), scanning electron microscopy (SEM), dynamic mechanical analysis (DMA), tensile tests, and thermogravimetric analysis (TGA). The results revealed that silica particles were homogeneously dispersed in soy protein matrix at a nanometer scale with low silica addition (lower than 15%). Silica particles exhibited a high adhesion with protein matrix through hydrogen bonding and confined the motions of soy protein segments. The incorporation of silica as a reinforcing agent significantly improved the mechanical properties and thermal stability of soy protein plastics. © The 2011 Author(s).

Zhao L.-C.,Northwest University, China | Li S.-C.,Xian Jiaotong University | Ling L.,South China University of Technology
Physical Review E - Statistical, Nonlinear, and Soft Matter Physics | Year: 2014

We investigate the solution in rational form for the Sasa-Satsuma equation on a continuous background which describes a nonlinear fiber system with higher-order effects including the third-order dispersion, Kerr dispersion, and stimulated inelastic scattering. The W-shaped soliton in the system is obtained analytically. It is found that the height of hump for the soliton increases with decreasing the background frequency in certain parameter regime. The maximum height of the soliton can be three times the background's height and the corresponding profile is identical with the one for the well-known eye-shaped rogue wave with maximum peak. The numerical simulations indicate that the W-shaped soliton is stable with small perturbations. Particularly, we show that the W-shaped soliton corresponds to a stable supercontinuum pulse by performing exact spectrum analysis. © 2014 American Physical Society.

Jiang Z.-J.,South China University of Technology | Jiang Z.,Ningbo University of Technology | Chen W.,Ningbo University of Technology
Journal of Power Sources | Year: 2014

Nitrogen doped holey graphene (NHG), with in-plane holes in its sheet plate, has been synthesized in this work through the potassium hydroxide (KOH) etching and ball milling of nitrogen doped graphene (NG). It shows that the KOH etching and ball milling does not distinctly alter the elemental composition and the relative percentages of functional groups in NG, but produce holes in its in-plane sheet plate. The obtained NHG can then be used as an active electrode material for supercapacitors and as an active electrocatalyst for oxygen reduction reaction, and exhibits significantly higher electrochemical performance than the corresponding NG. Its improved electrochemical performance could be attributed to its specific holey structure in the sheet plate and porous structure in its randomly stacked solid, which provide it with more active edge atoms, better accessibility to electrolyte, larger accommodation space for ions, faster electrolyte diffusion and movement and so on. © 2013 Elsevier B.V. All rights reserved.

Yan B.,South China University of Technology
International Journal of Production Research | Year: 2015

The study investigates two dynamic pricing strategies, namely posterior price matching (PM) and delay posterior price matching (DPM). These strategies are used by sellers to consider consumer behaviour in a market with several types of consumers. We analyze reduction season price, purchasing equilibrium and regular selling season price using equilibrium theory and backward induction method. A comparison of these two strategies indicates that both PM and DPM enable sellers to increase price in a regular selling season. Hassle cost and valuation differences between high- and low-end consumers influence the profits and decisions of the seller. PM is the best choice when valuations of low- and high-end consumers vary significantly. When the strategic consumer delaying fraction is small, the advantages of PM are more evident than those of DPM. However, DPM is the best choice when the difference between the valuations of low- and high-end consumers is small, and the strategic consumer delaying fraction is large. An increase in hassle cost also affects the seller’s strategy choice and profits; this effect decreases as strategic consumer delaying fraction increases. © 2015 Taylor & Francis

Zhang L.-Z.,South China University of Technology
International Journal of Heat and Mass Transfer | Year: 2010

Membrane-based total heat exchangers (or energy recovery ventilators) are the key equipments to fresh air ventilation, which is helpful for the control of respiratory diseases like Swine flu and SARs. Cross flow has been the predominant flow arrangement for these equipments. However performances are limited with this arrangement. A counter flow arrangement is the best. In this research, a quasi-counter flow parallel-plates total heat exchanger is constructed and investigated. A detailed mathematical modeling is conducted and the model is experimentally verified. The temperature and humidity values on membrane surfaces, and in the fluids are solved as a conjugate problem. The fluid flow, heat and mass transport equations in the entry regions are solved directly. The mean Nusselt and Sherwood numbers, and the sensible and latent effectiveness of the exchanger are calculated. It is found that the effectiveness of the current arrangement lie between those for cross flow and those for counter flow arrangements. The results also found that the flow can be divided distinctly into three zones: two cross-like zones and a pure-counter flow zone. The less the cross-like zones are, the larger the pure-counter flow zone is, and the greater the effectiveness is. The study also provides a solution of modeling mass transfer with FLUENT software from heat mass analogy. © 2010 Elsevier Ltd. All rights reserved.

Liang J.-Z.,South China University of Technology
Composites Part B: Engineering | Year: 2013

Polypropylene (PP) composites filled with aluminum hydroxide (Al(OH) 3) and magnesium hydroxide (Mg(OH) 2) were prepared using a twin-screw extruder. The effective thermal conductivity (k eff) of the composites was measured by means of a thermal conductivity instrument under different testing temperatures. The results showed that the values of k eff increased quickly with an increase the volume fraction (φ f) of Al(OH) 3/Mg(OH) 2 powder when φ f was less than 7.1%, then k eff increased slightly as φ f was varying from 7.1% to 13.3%, while the values of k eff increased obviously when φ f was more than 13.3%. Under the same conditions, the values of k eff increased nonlinearly with increasing the diameter (d) of the Al(OH) 3/Mg(OH) 2 powder. The values of k eff of the composites increased somewhat with a rise of test temperature. On the basis of the experimental results, the thermal conduction mechanisms of the composite were analyzed and discussed. © 2012 Published by Elsevier Ltd.

Gao G.,Friedrich - Alexander - University, Erlangen - Nuremberg | Peng M.,South China University of Technology | Wondraczek L.,Friedrich - Alexander - University, Erlangen - Nuremberg
Optics Letters | Year: 2012

Ultrabroad near-infrared (NIR) photoluminescence from Ni 2+-centers in nanocrystalline Ba-Al titanate glass ceramics was studied by temperature-dependent static and dynamic photoluminescence spectroscopy in the regime of 10 to 300 K. Photoluminescence covers the spectral range of about 1100 nm to >1600 nm with a typical bandwidth (FWHM) greater than 300 nm. For UV-LED excitation at 352 nm, an internal quantum efficiency of 65% is obtained. The excited state lifetime τ at room temperature is 39 μs. The stimulated emission cross section σem is 8.5 × 10 -20 cm2, resulting in a practical figure of merit, σem * τ, of 3.3 × 10-24 cm2 s at room temperature. These properties suggest suitability as a broadband gain medium for tunable lasers and optical amplifiers. © 2012 Optical Society of America.

Liang J.-Z.,South China University of Technology
Polymer International | Year: 2012

Ternary composites of glass fiber-reinforced poly(p-phenylene sulfide) (PPS/GF) filled with nanometric calcium carbonate (nano-CaCO 3) were prepared by means of a twin-screw extruder. The nano-CaCO 3 surface was treated with stearate and treated with titanate, the composites being called SI composite system and SII composite system, respectively. The crystallization and heatproof properties of the PPS/GF/nano-CaCO 3 composites were measured using a differential scanning calorimeter, to investigate the influence of the nanometric filler content on the crystallinity. The results show that the variation of the starting crystallization temperature, crystallization temperature and crystallinity with an increase of the particle weigh fraction (φ{symbol} f) of SI composite system is different from that of SII composite system. When φ{symbol} f is less than 4 wt%, the crystallinity of the two composite systems increases and then decreases slightly with increasing φ{symbol} f. Moreover, the crystallization behavior and mechanisms are discussed. © 2011 Society of Chemical Industry.

Zu L.,South China University of Technology | Zu L.,Technical University of Delft
Composite Structures | Year: 2012

In this paper the fiber trajectory stability of filament wound toroidal pressure vessels is evaluated for two most frequently used patterns: single helical winding, helical and hoop winding. The basic equations of equilibrium for fibers on a torus are given based on netting analysis. The governing equations that determine helical winding angles along the meridional direction are derived for the two winding patterns. The slippage coefficients of the obtained fiber trajectories are calculated using the non-geodesic law and differential geometry. The condition between the hoop-to-helical thickness ratio and the relative bend radius of the toroid is also formulated to prevent fiber bridging on the concave surface. The fiber slippage and bridging tendencies are outlined and compared, corresponding to various relative bend radii and hoop-to-helical thickness ratios. The results show that the single helical winding process provides better stability of fiber trajectories, in terms of both fiber slippage and bridging, than the helical and hoop winding. The toroidal vessel with larger relative bend radius requires lower coefficient of friction between the fiber bundle and the supporting surface. The present analysis for fiber trajectory stability affords a useful reference tool for designing filament-wound toroidal pressure vessels. © 2011 Elsevier Ltd.

Huang H.,University of Hong Kong | Leung D.Y.C.,University of Hong Kong | Ye D.,South China University of Technology
Journal of Materials Chemistry | Year: 2011

A series of highly active Pt/TiO2 catalysts were prepared by impregnation and deposition precipitation methods with different reduction processes. Their catalytic activities were evaluated by catalytic decomposition of formaldehyde (HCHO) at room temperature. The effects of reduction treatment on structural properties and catalytic activity were studied. Reduced Pt/TiO2 catalysts showed large differences in structural properties (such as particle size, oxidation state, surface content and electronic property of Pt nanoparticles, and surface oxygen) and catalytic activity for HCHO oxidation compared with the unreduced ones. Nearly 100% HCHO conversion was achieved on the former. Especially, sodium borohydride reduced Pt/TiO 2 catalysts even with 0.1% Pt loading showed nearly complete oxidation of HCHO. Well-dispersed and negatively charged metallic Pt nanoparticles, and rich chemisorbed oxygen are probably responsible for their high catalytic activities. © 2011 The Royal Society of Chemistry.

Zhang X.W.,South China University of Technology
Computational Biology and Chemistry | Year: 2013

In silico identification of T-cell epitopes is emerging as a new methodology for the study of epitope-based vaccines against viruses and cancer. In order to improve accuracy of prediction, we designed a novel approach, using epitope prediction methods in combination with molecular docking techniques, to identify MHC class I restricted T-cell epitopes. Analysis of the HIV-1 p24 protein and influenza virus matrix protein revealed that the present approach is effective, yielding prediction accuracy of over 80% with respect to experimental data. Subsequently, we applied such a method for prediction of T-cell epitopes in SARS coronavirus (SARS-CoV) S, N and M proteins. Based on available experimental data, the prediction accuracy is up to 90% for S protein. We suggest the use of epitope prediction methods in combination with 3D structural modelling of peptide-MHC-TCR complex to identify MHC class I restricted T-cell epitopes for use in epitope based vaccines like HIV and human cancers, which should provide a valuable step forward for the design of better vaccines and may provide in depth understanding about activation of T-cell epitopes by MHC binding peptides. © 2013 Elsevier B.V. All rights reserved.

Liu X.,South China University of Technology
IEEE Communications Letters | Year: 2014

An effective transmission strategy should achieve maximum possible energy efficiency (MPEE) and maximum possible energy balancing (MPEB) for lifespan maximization in wireless sensor networks (WSNs). In this letter, a transmission scheme with two strategies of MPEB is proposed to realize the unity of MPEE and MPEB, and ultimately to maximize the lifetime of WSNs. This transmission scheme is based on ant colony optimization (ACO), but it is quite different from conventional ACO algorithms in two aspects: every ant only needs to move one step to finish its complete trip, and there is no heuristic information in the transition probability of the ant. Finally, simulations are used to validate the effectiveness and superiority of our proposed transmission scheme. © 2014 IEEE.

Xie B.-S.,South China University of Technology
Journal of the Acoustical Society of America | Year: 2012

Head-related transfer functions (HRTFs) vary with individuals, and in practice, measuring HRTFs with high directional resolution for each individual is tiresome. Based on a basis functions representation of HRTFs, the present work proposes a method for recovering individual HRTFs from a small set of measurements. The HRTFs are represented by a combination of a small set of spatial basis functions (SBFs) with frequency- and individual-dependent weights. The SBFs are derived by applying spatial principal component analysis to a baseline HRTF dataset with high directional resolution. The individual weights for any subject outside the dataset are estimated from measurements at a few source directions, and then the HRTFs with high directional resolution are recovered by combining the SBFs and the individual weights. In an illustrative case, the SBFs derived from a baseline dataset that includes 20 subjects are used to recover the HRTF magnitudes for six subjects outside the baseline dataset. Results show that individual HRTF magnitudes can be recovered from measurements at 73 directions with a mean signal-to-distortion ratio of 19 dB. The proposed method is also applicable to recovering head-related impulse responses. The results of psychoacoustic experiments indicate that in most cases the recovered and measured HRTFs are indistinguishable. © 2012 Acoustical Society of America.

Zheng J.,University of Newcastle | Su W.,South China University of Technology | Fu M.,University of Newcastle
IEEE/ASME Transactions on Mechatronics | Year: 2010

This paper first reveals that the tracking and disturbance rejection problems can be decoupled into two independent optimization problems under the 2-DOF control framework. This result is then used for the design of a 2-DOF controller for a dual-stage actuator (DSA) system to provide desired performance of disturbance rejection and step tracking. The 2-DOF controller is designed based on the doubly coprime factorization approach, with which the closed-loop transfer function is expressed explicitly in terms of design parameters. This greatly simplifies the optimization of design parameters in meeting desired specifications. We further study how to use the design parameters to deal with specific problems in the DSA, i.e., control allocation and trajectory planning. For step tracking beyond the secondary actuator range, a nonlinear controller is also used for the primary actuator to complete the task. Experimental results demonstrate the practical implementation of the DSA control system and verify its effectiveness for step tracking and disturbance rejection and its robust performance under load changes. © 2006 IEEE.

Lu C.,Ohio State University | Zhao J.,Ohio State University | Yang S.-T.,Ohio State University | Wei D.,Ohio State University | Wei D.,South China University of Technology
Bioresource Technology | Year: 2012

Concentrated cassava bagasse hydrolysate (CBH) containing 584.4. g/L glucose was studied for acetone-butanol-ethanol (ABE) fermentation with a hyper-butanol-producing Clostridium acetobutylicum strain in a fibrous bed bioreactor with gas stripping for continuous butanol recovery. With periodical nutrient supplementation, stable production of n-butanol from glucose in the CBH was maintained in the fed-batch fermentation over 263. h with an average sugar consumption rate of 1.28. g/L. h and butanol productivity of 0.32 ± 0.03. g/L. h. A total of 108.5. g/L ABE (butanol: 76.4. g/L, acetone: 27.0. g/L, ethanol: 5.1. g/L) was produced, with an overall yield of 0.32 ± 0.03. g/g glucose for ABE and 0.23 ± 0.01. g/g glucose for butanol. The gas stripping process generated a product containing 10-16% (w/v) of butanol, ∼4% (w/v) of acetone, a small amount of ethanol (<0.8%) and almost no acids, resulting in a highly concentrated butanol solution of ∼64% (w/v) after phase separation. © 2011 Elsevier Ltd.

Xiao L.-P.,Beijing Forestry University | Shi Z.-J.,Beijing Forestry University | Xu F.,Beijing Forestry University | Sun R.-C.,Beijing Forestry University | Sun R.-C.,South China University of Technology
Bioresource Technology | Year: 2012

Hydrothermal carbonization (HTC) is a novel thermochemical conversion process to convert lignocellulosic biomass into value-added products. HTC processes were studied using two different biomass feedstocks: corn stalk and Tamarix ramosissima. The treatment brought an increase of the higher heating values up to 29.2 and 28.4. MJ/kg for corn stalk and T. ramosissima, respectively, corresponding to an increase of 66.8% and 58.3% as compared to those for the raw materials. The resulting lignite-like solid products contained mainly lignin with a high degree of aromatization and a large amount of oxygen-containing groups. Liquid products extracted with ethyl acetate were analyzed by gas chromatography-mass spectrometry. The identified degradation products were phenolic compounds and furan derivatives, which may be desirable feedstocks for biodiesel and chemical production. Based on these results, HTC is considered to be a potential treatment in a lignocellulosic biomass refinery. © 2012 Elsevier Ltd.

Xue-Tao X.,HKUST Fok Ying Tung Graduate School | Kai-Yi L.,University of Maine, France | Jia-Ying Z.,South China University of Technology
Biosensors and Bioelectronics | Year: 2015

A portable and sensitive quantitative DNA detection method based on personal glucose meters and isothermal circular strand-displacement polymerization reaction was developed. The target DNA triggered target recycling process, which opened capture DNA. The released target then found another capture DNA to trigger another polymerization cycle, which was repeated for many rounds, resulting in the multiplication of the DNA-invertase conjugation on the surface of Streptavidin-MNBs. The DNA-invertase was used to catalyze the hydrolysis of sucrose into glucose for PGM readout. There was a liner relationship between the signal of PGM and the concentration of target DNA in the range of 5.0 to 1000. fM, which is lower than some DNA detection method. In addition, the method exhibited excellent sequence selectivity and there was almost no effect of biological complex to the detection performance, which suggested our method can be successfully applied to DNA detection in real biological samples. © 2014 Elsevier B.V.

Yi H.,South China University of Technology | Yang J.,Queensland University of Technology
Habitat International | Year: 2014

Natural disasters can have adverse effect on human lives. To raise the awareness of research and better combat future events, it is important to identify recent research trends in the area of post disaster reconstruction (PDR). The authors used a three-round literature review strategy to study journal papers published in the last decade that are related to PDR with specific conditions using the Scopus search engine. A wide range of PDR related papers from a general perspective was examined in the first two rounds while the final round established 88 papers as target publications through visual examination of the abstracts, keywords and as necessary, main texts. These papers were analysed in terms of research origins, active researchers, research organisations, most cited papers, regional concerns, major themes and deliverables, for clues of the past trends and future directions. The need for appropriate PDR research is increasingly recognised. The publication number multiplied 5 times from 2002 to 2012. For PDR research with a construction perspective, the increase is sixfold. Developing countries such as those in Asia attract almost 50% researchers' attention for regional concerns while the US is the single most concentrated (24%) country. Africa is hardly represented. Researchers in developed countries lead in worldwide PDR research. This contrasts to the need for expertise in developing countries. Past works focused on waste management, stakeholder analysis, resourcing, infrastructure issue, resilience and vulnerability, reconstruction approach, sustainable reconstruction and governance issues. Future research should respond to resourcing, integrated development, sustainability and resilience building to cover the gaps. By means of a holistic summary and structured analysis of key patterns, the authors hope to provide a streamlined access to existing research findings and make predictions of future trends. They also hope to encourage a more holistic approach to PDR research and international collaborations. © 2013 Elsevier Ltd.

Xie W.,South China University of Technology
IET Control Theory and Applications | Year: 2016

This study focuses on the design of a switching controller, which includes several linear time-invariant (LTI) controllers designed beforehand and independently, for a specific LTI plant. All of these LTI controllers are capable of stabilising the plant with corresponding H∞ control performance criterions. It is shown that there exist suitable state space realisations of these controller transfer matrices that guarantee not only certain H∞ control performance of the overall closed-loop system under arbitrary switching but also corresponding H∞ performances of local closed-loop systems at switching points. © 2016 The Institution of Engineering and Technology.

Li M.,CAS Shanghai Institutes for Biological Sciences | Zeng T.,CAS Shanghai Institutes for Biological Sciences | Liu R.,South China University of Technology | Chen L.,CAS Shanghai Institutes for Biological Sciences
Briefings in Bioinformatics | Year: 2014

Identifying early warning signals of critical transitions during disease progression is a key to achieving early diagnosis of complex diseases. By exploiting rich information of high-throughput data, a novel model-free method has been developed to detect early warning signals of diseases. Its theoretical foundation is based on dynamical network biomarker (DNB), which is also called as the driver (or leading) network of the disease because components or molecules in DNB actually drive the whole system from one state (e.g. normal state) to another (e.g. disease state). In this article, we first reviewed the concept and main results of DNB theory, and then applied the new method to the analysis of type 2 diabetes mellitus (T2DM). Specifically, based on the temporal-spatial gene expression data of T2DM, we identified tissue-specific DNBs corresponding to the critical transitions occurring in liver, adipose and muscle duringT2DM development and progression. Actually, we found that there are two different critical states during T2DM development characterized as responses to insulin resistance and serious inflammation, respectively. Interestingly, a new T2DM-associated function, i.e. steroid hormone biosynthesis, was discovered, and those related genes were significantly dysregulated in liver and adipose at the first critical transition during T2DM deterioration. Moreover, the dysfunction of genes related to responding hormone was also detected in muscle at the similar period. Based on the functional and network analysis on pathogenic molecular mechanism of T2DM, we showed that most of DNB genes, in particular the core ones, tended to be located at the upstream of biological pathways, which implied that DNB genes act as the causal factors rather than the consequence to drive the downstream molecules to change their transcriptional activities. This also validated our theoretical prediction of DNB as the driver network. As shown in this study, DNB can not only signal the emergence of the critical transitions for early diagnosis of diseases, but can also provide the causal network of the transitions for revealing molecular mechanisms of disease initiation and progression at a network level. © The Author 2013. Published by Oxford University Press.

Li Z.,South China University of Technology | Xia Y.,Beijing Institute of Technology | Sun F.,Tsinghua University
IEEE Transactions on Fuzzy Systems | Year: 2014

In this paper, an adaptive fuzzy control is investigated for multilateral teleoperation of two cooperating robotic manipulators that manipulate an object with constrained trajectory/force in the presence of dynamics uncertainties and random network-induced delays. First, the interconnected dynamics that consist of two master robots and cooperating slave robots are formulated. To consider multiple stochastic delays in communication channels, Markov processes are used to model these random network-induced delays. The interconnected dynamics of the teleoperation are divided into a local master/slave position/force subsystem and a stochastic-delayed motion synchronization subsystem. Then, an adaptive fuzzy control strategy, which is based on linear matrix inequalities (LMIs) that combine adaptive update techniques, is proposed to suppress the dynamics uncertainties, the external disturbances, and the multiple stochastic delays in communication channels. The control approach ensures that the defined synchronization errors converge to zero. The stochastic stability in mean square of the closed-loop system is proved using LMIs based on Lyapunov-Krasovskii functional synthesis. The proposed controls are validated using extensive simulation studies. © 1993-2012 IEEE.

Zhang H.,South China University of Technology
Applied Physics Letters | Year: 2011

In this letter, on the basis of Stoner-Wohlfarth model, the changes in magnetization of Tb0.3Dy0.7 Fe2 alloy have been calculated with a compressive stress along the [111] and [112] axes. The results have shown that the significant change in magnetization for Tb 0.3 Dy0.7 Fe2 alloy can be induced by the compressive stress. A feasible application of power generation floor which can convert the energy from the vibration created by a walking person on it into electric energy has been proposed, and its structure and performance also have been revealed. © 2011 American Institute of Physics.

Gao G.,Friedrich - Alexander - University, Erlangen - Nuremberg | Reibstein S.,Friedrich - Alexander - University, Erlangen - Nuremberg | Peng M.,Friedrich - Alexander - University, Erlangen - Nuremberg | Peng M.,South China University of Technology | Wondraczek L.,Friedrich - Alexander - University, Erlangen - Nuremberg
Journal of Materials Chemistry | Year: 2011

We report on tunable photoluminescence from mixed-valence Eu-doped nanocrystalline Li 2ZnSiO 4 glass ceramics. After preparation of the precursor glass in air, gradual reduction of Eu 3+ to Eu 2+ occurs intrinsically during thermal annealing and precipitation of crystalline Li 2ZnSiO 4. Dual-mode photoemission can be generated for exciting at a wavelength of about 360 nm. The resulting colour of luminescence, ranging from orange/red to blue, can be controlled by adjusting the annealing temperature and, hence, the degree of crystallization: with increasing annealing temperature, the ratio of luminescence intensities related to Eu 3+ and Eu 2+ species, respectively, varies as a result of increasing degree of Eu 3+- reduction as well as distinct changes in the optical scattering behaviour of the obtained glass ceramic. At the same time, the bandwidth of Eu 2+-related photoemission increases from 87 to 154 nm. The underlying mechanisms of photoemission and energy transfer from Eu 2+ to Eu 3+ are discussed on the basis of dynamic emission spectroscopy and structural considerations, and a description of the internal reduction process is given. © The Royal Society of Chemistry 2011.

Cheng J.,South China University of Technology | Huang G.,East China Normal University
Physical Review A - Atomic, Molecular, and Optical Physics | Year: 2011

We propose a scheme to realize a transition from delocalization to localization of light waves via electromagnetically induced transparency. The system we suggested is a resonant cold atomic ensemble having N configuration, with a control field consisting of two pairs of laser beams with different cross angles, which produce an electromagnetically induced quasiperiodic waveguide (EIQPW) for the propagation of a signal field. By appropriately tuning the incommensurate rate or relative modulation strength between the two pairs of control-field components, the signal field can exhibit the delocalization- localization transition as it transports inside the atomic ensemble. The delocalization-localization transition point is determined and the propagation property of the signal field is studied in detail. Our work provides a way of realizing wave localization via atomic coherence, which is quite different from the conventional, off-resonant mechanism-based Aubry-Andre model, and the great controllability of the EIQPW also allows an easy manipulation of the delocalization-localization transition. © 2011 American Physical Society.

Xie J.H.,Guangdong University of Technology | Huang P.Y.,South China University of Technology | Guo Y.C.,Guangdong University of Technology
Construction and Building Materials | Year: 2012

A series of experiments were conducted to investigate the fatigue damage behavior of reinforced concrete (RC) beams strengthened with prestressed fiber reinforced polymer (FRP) under three-point bending. Based on the experimental results, the fatigue failure mechanism of the strengthened beams and the propagation process of the fatigue interface cracks were presented, and an empirical formula was developed to predict the fatigue lives of such members. Moreover, a theoretical method was proposed to quantify the dynamic flexural stiffness of the strengthened beams. Based on the flexural stiffness, a fatigue accumulative damage model was established to describe the fatigue fracture process of the strengthened beams. The results show that the theoretical model is in good agreement with the experimental data. © 2011 Elsevier Ltd. All rights reserved.

Zhang H.,South China University of Technology
Journal of Magnetism and Magnetic Materials | Year: 2012

The PZT/Insulator/CoFe nanometer multilayer has been proposed for applications of the spin-dependent devices in this paper. With the strains as a response of PZT layer to an applied electric field in the structure, the magnetization in CoFe layer can be significantly altered, leading to a significance change in magnetoresistance. Our numerical results have demonstrated that the magnetization states in CoFe layer can be tuned by an electric field without a magnetic field being present. © 2012 Elsevier B.V.

Liang J.-Z.,South China University of Technology
Composites Part B: Engineering | Year: 2012

An expression of Young's modulus of short inorganic fiber reinforced polymer composites was derived based on the tensile strength equation proposed in the previous paper, and the factor affecting the Young's modulus was analyzed. This equation was applied to estimate the Young's modulus of short inorganic fiber reinforced polymer composites. The results showed that the relative Young's modulus increased nonlinearly with increasing fiber volume fraction, while increased linearly with an increase of fiber length-diameter ratio. Finally, the equation was verified preliminarily by using the measured Young's modulus of the short glass fiber (SGF) reinforced polycarbonate/ acrylnitrile-butadiene-styrene copolymer composites and the polypropylene reinforced respectively with SGF and short carbon fiber reported from literature, good agreement was found between the predictions and the experimental data. © 2012 Elsevier Ltd. All rights reserved.

Ling L.,South China University of Technology | Zhao L.-C.,Northwest University, China
Physical Review E - Statistical, Nonlinear, and Soft Matter Physics | Year: 2013

We present a simple representation for arbitrary-order rogue wave solution and a study on the trajectories of them explicitly. We find that the trajectories of two valleys on whole temporal-spatial distribution all look "X" -shaped for rogue waves. Additionally, we present different types of high-order rogue wave structures, which could be helpful towards realizing the complex dynamics of rogue waves. © 2013 American Physical Society.

Liang J.Z.,South China University of Technology
International Journal of Materials and Product Technology | Year: 2010

A 3-D simulation of interfacial stress distribution between particulate and matrix during tension of a polypropylene/calcium carbonate is made by means of a finite element method with ANSYS. The results show that the shear stress increases with increasing the angle from the equator of the particle (α) and reaches maximum around 20°. The tensile stress at Y direction increases with increasing α then slightly varies when α is more than 50°. The tensile stress at X direction decreases with increasing α and reaches the minimum around 35°. The stress distribution of 3-D model is gentler than that of 2-D model. © 2010 Inderscience Enterprises Ltd.

Zhu S.,University of South Florida | Zhu S.,South China University of Technology | Xu X.,University of South Florida | Perman J.A.,University of South Florida | Zhang X.P.,University of South Florida
Journal of the American Chemical Society | Year: 2010

[Co(P1)], the cobalt(II) complex of the D2-symmetric chiral porphyrin 3,5-DitBu-ChenPhyrin, is an effective catalyst for catalyzing asymmetric olefin cyclopropanation with the acceptor/acceptor-type diazo reagent α-cyanodiazoacetates. The [Co(P1)]-catalyzed reaction is versatile and suitable for both aromatic and aliphatic olefins with varied electronic properties, including electron-rich and-poor olefins. The Co(II)-based catalytic system can be operated in a one-time protocol under mild conditions, affording the desired cyclopropane products in high yields with both high diastereo-and enantioselectivity. The resulting enantiomerically enriched 1,1-cyclopropanenitrile esters provide convenient access to a number of densely functionalized chiral cyclopropane derivatives, including α-cyclopropyl- β-amino acids. © 2010 American Chemical Society.

Gu G.-Y.,Shanghai JiaoTong University | Zhu L.-M.,Shanghai JiaoTong University | Su C.-Y.,South China University of Technology | Su C.-Y.,Concordia University at Montreal
IEEE Transactions on Industrial Electronics | Year: 2014

This paper presents a modified Prandtl-Ishlinskii (P-I) (MPI) model for the asymmetric hysteresis description and compensation of piezoelectric actuators. Considering the fact that the classical P-I (CPI) model is only efficient for the symmetric hysteresis description, the MPI model is proposed to describe the asymmetric hysteresis nonlinearity of piezoceramic actuators (PCAs). Different from the commonly used approach for the development of asymmetric P-I models by replacing the classical play operator with complex nonlinear operators, the proposed MPI model still utilizes the classical play operator as the elementary operator, while a generalized input function is introduced to replace the linear input function in the CPI model. By this way, the developed MPI model has a relative simple mathematic format with fewer parameters to characterize the asymmetric hysteresis behavior of PCAs. The benefit for the developed MPI model also lies in the fact that an analytic inverse model of the CPI model can be directly applied for the inverse compensation of the asymmetric hysteresis nonlinearity represented by the developed MPI model in real-time applications. To validate the developed MPI model and the inverse hysteresis compensator, simulation, and experimental results on a piezoceramic actuated platform are presented. © 1982-2012 IEEE.

Pei L.,South China University of Technology | Gao H.,Sun Yat Sen University
Journal of Molecular Catalysis A: Chemical | Year: 2011

A novel fluorinated bis(β-ketoamino) copper complex was synthesized and characterized. Norbornene polymerizations with bis(β-ketoamino) copper complexes activated with methylaluminoxane (MAO) were investigated. The highest catalytic activity up to now reported for copper based systems in norbornene polymerization was achieved using fluorinated bis(β-ketoamino) copper/MAO. The influence of precursor structure including steric and electronic effects on catalytic activity for norbornene polymerization was evaluated in detail. Bulky steric substituents and strong electron-withdrawing groups can enhance catalytic activity of precursor for norbornene polymerization through a dissociative mechanism. The influences of polymerization parameters such as polymerization temperature and Al/Cu ratio on norbornene polymerization with bis(β-ketoamino) copper catalysts were also examined. Norbornene polymerization catalyzed by bis(β-ketoamino) copper complexes/MAO proceeded on Cu(I) species through a coordination/insertion mechanism to produce vinyl-addition polynorbornene. © 2011 Elsevier B.V.

Zhang H.,South China University of Technology
Journal of Magnetism and Magnetic Materials | Year: 2012

In this paper, domain rotations in Tb0.3Dy0.7Fe 2 alloy under a compressive stress applied along various crystallographic axes alone have been investigated on the basis of 3D StonerWohlfarth model by following the conventional free energy minimization procedure. The dependence of both the domain rotations and the strains caused by the compressive stress on the stress directions has been revealed. And it has been found that the anisotropic magnetomechanical effect arises from the dependence of the stress induced anisotropy on the stress direction. This study is very helpful for the better understanding of magnetic behavior of magnetostrictive materials under both stress and field. © 2011 Elsevier B.V. All rights reserved.

Zhu R.,South China University of Technology | Berakdar J.,Martin Luther University of Halle Wittenberg
Physical Review B - Condensed Matter and Materials Physics | Year: 2010

We study the pump current and noise properties in an adiabatically modulated magnetic nanowire with double domain walls (DWs). The modulation is brought about by applying a slowly oscillating magnetic and electric fields with a controllable phase difference. The pumping mechanism resembles the case of the quantum dot pump with two-oscillating gates. The pump current, shot noise, and heat flow show peaks when the Fermi energy matches with the spin-split resonant levels localized between the DWs. The peak height of the pump current is an indicator for the lifetime of the spin-split quasistationary states between the DWs. For sharp DWs, the energy absorption from the oscillating fields results in sideband formations observable in the pump current. The pump noise carries information on the correlation properties between the nonequilibrium electrons and the quasiholes created by the oscillating scatterer. The ratio between the pump shot noise and the heat flow serves as an indicator for quasiparticle correlation. © 2010 The American Physical Society.

Li Y.C.,City University of Hong Kong | Xue Q.,City University of Hong Kong | Zhang X.Y.,South China University of Technology
IEEE Transactions on Microwave Theory and Techniques | Year: 2013

This paper presents a novel device integrating a power divider with two bandpass filters. It is capable of splitting power and selecting frequency at the same time. The phase shift of the filter is found to be ±90° at the center frequency. Therefore, when it is matched to 70.7 Ω, it can replace the conventional quarter-wave length transmission line in the power divider. The isolation elements are loaded at the filters' open ends to get a good isolation between the output ports. As a result, both the transmission and isolation property are satisfied. The equivalent even-and odd-mode circuits of the proposed structure are analyzed and design equations are derived. They are used to guide the design of the devices. For demonstration, filter-integrated power dividers with single-and dual-band operation are implemented, respectively. Comparisons of the measured and simulated results are presented to verify the theoretical predications. © 1963-2012 IEEE.

Huang Y.-X.,South China University of Technology
Chung-kuo Tsao Chih/China Pulp and Paper | Year: 2013

The problems appeared in operation of the hydraulic medium consistency refiner were analyzed based on medium refining principle and the structure of the refiner. The measures of upgrade and improvement of the refiner the proposed.

Wu Y.-N.,Zhao Qing University | Liao S.-J.,South China University of Technology | Guo H.-F.,Zhao Qing University | Hao X.-Y.,Zhao Qing University
Journal of Power Sources | Year: 2013

A high-performance, low platinum loading catalyst for the anodic oxidation of methanol, Pd@PtRu/C, is prepared by a two-step colloidal approach. The activity of the Pd@PtRu/C catalyst is 1.67 times and 1.81 times that of PtRu/C and PtRuPd/C catalysts, respectively. The catalysts are characterized by TEM, XPS, and XRD. The active components are dispersed on the surface of the carbon support very well, yielding a particle size of ca. 4.7 nm and a shell thickness of ca. 0.25 nm. The catalyst's high activity may be attributed to the high exposure and dispersion of PtRu, as well as the interaction of PtRu in the shell layer with Pd in the core, resulting from the catalyst's core-shell structure. © 2012 Elsevier B.V. All rights reserved.

Su S.-J.,South China University of Technology | Cai C.,Yamagata University | Kido J.,Yamagata University
Journal of Materials Chemistry | Year: 2012

A series of three-carbazole-armed host materials containing various arylene cores, like benzene (1,3,5-tris(3-(carbazol-9-yl)phenyl)-benzene, TCPB), pyridine (2,4,6-tris(3-(carbazol-9-yl)phenyl)-pyridine, TCPY), and pyrimidine (2,4,6-tris(3-(carbazol-9-yl)phenyl)-pyrimidine, TCPM), were developed for red, green, and blue phosphorescent organic light-emitting diodes (OLEDs). An intramolecular charge transfer was observed for TCPY and TCPM with heterocyclic cores of pyridine and pyrimidine, giving bathochromic shifts in the photoluminescent spectrum and reduced energy band gaps in comparison with TCPB with a benzene core. In addition, lower energy singlet and triplet excited states, reduced lowest unoccupied molecular orbital (LUMO) energy level, smaller singlet-triplet exchange energy (ΔE ST), and improved bipolarity were also achieved with introducing heterocycles of pyridine and pyrimidine instead of benzene. In contrast to the slightly decreased triplet energy (E T), a significantly decreased ΔE ST was achieved by introducing heterocycles of pyridine and pyrimidine as the core, and the more nitrogen atoms in the central heterocycle, the smaller ΔE ST is achieved. Reduced driving voltages were achieved for the green and red phosphorescent OLEDs by utilizing TCPY and TCPM as the host due to their decreased ΔE ST and lower-lying LUMO energy level, proving that more carriers must be injected into the emitting layer through the host molecules rather than direct carrier trapping by the dopant. Moreover, improved efficiency and suppressed efficiency roll-off were also achieved for the green and red phosphorescent OLEDs based on TCPY and TCPM due to their improved bipolarity and thus improved carrier balance. © 2012 The Royal Society of Chemistry.

Liang J.-Z.,South China University of Technology
Composites Part B: Engineering | Year: 2014

The thermal conductivity of hollow glass bead (HGB)-filled polypropylene (PP) composites was estimated using the thermal conductivity equation of inorganic hollow microsphere-filled polymer composites published in the previous paper. The estimations were compared with the measured data of the PP composites filled with two kinds of HGB with different size (the mean diameter was respectively 35 μm and 70 μm). The results showed that the predictions of the thermal conductivity were in good agreement with the measured data except to individual data points. Furthermore, both the estimated and measured thermal conductivity decreased roughly linearly with increasing the HGB volume fraction when the HGB volume fraction was less than 20%; the influence of the particle diameter on the thermal conductivity was insignificant. © 2013 Published by Elsevier Ltd.

Wen Y.,Guangdong Ocean University | Jiang H.,South China University of Technology
Tetrahedron Letters | Year: 2013

An efficient procedure for the synthesis of a series of 1-bromo-1,4-dienes by a simple Pd-catalyzed intermolecular tandem reaction of alkynes, CuBr 2, and allylic alcohol has been developed. The reaction proceeds smoothly under mild condition to give the corresponding products in good to excellent yields. © 2013 The Authors. Published by Elsevier Ltd. All rights reserved.

Sun H.-T.,Soochow University of China | Sun H.-T.,Hokkaido University | Zhou J.,China Jiliang University | Zhou J.,Zhejiang University | Qiu J.,South China University of Technology
Progress in Materials Science | Year: 2014

Bismuth is one of the most thoroughly investigated main group elements, which has been regarded as 'the wonder metal' because of its diverse oxidation states and profound propensities to form bismuth clusters, resulting from the easy involvement in chemical combinations for the electrons in the p orbital. This peculiarity allows them to behave as smart optically active centers in diverse host materials. Remarkable progress in the research of bismuth activated photonic materials has been seen over the last ten years owing to their unique properties and important applications in areas of telecommunication, biomedicine, white light illumination and lasers. The aim of this review is to present a critical overview of the current state of the art in bismuth activated photonic materials, their features, advantages and limitations as well as the future research trends. We first shortly introduce the fundamental properties of bismuth element including principles of bismuth-related luminescence and characterization techniques available. This is followed by a detailed discussion on the recent progress in the synthesis and characterization of bismuth-activated photonic materials, with an emphasis on material systems emitting in the near-infrared (NIR) spectral region. Furthermore, we describe the representative achievements regarding their prospective applications in broadband NIR optical amplifiers, fiber lasers, bioimaging, and white light-emitting diodes. Finally, we point out what key scientific questions remain to be answered, and present our perspectives on future research trends in this exciting field of sciences. © 2014 Elsevier Inc. All rights reserved.

Cai W.,South China University of Technology | Jing N.,North Carolina State University
European Journal of Combinatorics | Year: 2012

An explicit computation is made for a Laplace-Beltrami type operator for Jack polynomials. As applications we obtain: combinatorial formula, determinantal formula and raising operator formula for Jack polynomials, as well as an iterative formula for the Littlewood-Richardson coefficients. One special case of our results implies Mimachi-Yamada's result on Jack polynomials of rectangular shapes. © 2011 Elsevier Ltd.

Zhang X.Y.,South China University of Technology | Xue Q.,City University of Hong Kong
IEEE Transactions on Microwave Theory and Techniques | Year: 2010

This paper presents harmonic-suppressed tunable bandpass filters with two movable transmission zeros. For tunable bandpass filters, tuning the passband frequency will cause the harmonic to shift, complicating the harmonic suppression. To overcome this problem, lumped elements are utilized to realize harmonic suppression without degrading passband performance. It is found from theoretical analysis that at even-order harmonic frequencies, the lumped elements could not only decrease the resonator Q and dissipate RF power, but also control even-order impedance and cause mismatching at filter input/output ports. Both of the factors help reject even-order harmonics. Meanwhile, the features at fundamental resonant frequencies are nearly not affected by these elements, indicating harmonic suppression could be achieved without affecting passband performance. This property is experimentally verified by comparing the responses of tunable bandpass filters with and without harmonic suppression. Finally, a harmonic-suppressed tunable bandpass filter with constant bandwidth and passband shape is designed. A novel input and output coupling structure with a bandpass response is employed to maintain constant bandwidth and help reject both even- and odd-order harmonics. For each tuning state, two transmission zeros are created near the passband, ensuring high selectivity. © 2006 IEEE.

Hu J.-F.,Jiangxi University of Science and Technology | Zhang X.-M.,South China University of Technology
Guangxue Jingmi Gongcheng/Optics and Precision Engineering | Year: 2012

To achieve the precise motion of a 3-RRR compliant parallel precision positioning stage, a closed-form exact motion model was established and the optimized design of structure parameters was investigated. The Castigliano's second theorem was applied to establishment of the closed-form compliance model for the precision positioning stage. According to the structural characteristics of compliant parallel mechanisms, the system was divided into three symmetrical motion sub-chains. Combining the compliance equations of flexure hinge with the force transmission relations of mechanisms, the stiffness model of each sub-chain was obtained, and the stiffness of the entire system was calculated by summing the stiffness of three sub-chains in the same coordinate system. The proposed stiffness model took the hinge flexibility as the independent variables in the closed form. According to the flexibility matrix, the Jacobian matrix to reflect the relationship between input displacement and output one could be derived. By comparing the kineamatic model between theoretical analysis and FEA, the results show that the errors are within 1.0%~9.5%, which illurastrates that the proposed kinematic model is correct and precise. According to the closed-form Jacobian matrix, its sensitivity to structureal parameters was analyzed, then the design variables with greater impact on the kinematic properties were chosen. By taking the maxmium workspace as a target and the hinge strength, maxmium input forces, geometric dimensions and input coupling as the constrains, an optimal model was proposed. The results show that the optimized structural parameters can obtain more output displacements, and the proposed model can meet the design requirement.

Mu Y.,South China University of Technology
Physical Review E - Statistical, Nonlinear, and Soft Matter Physics | Year: 2011

We studied the effects of surface hydrophobicity on the conformational changes of different length polypeptides by calculating the free energy difference between peptide structures using the bias-potential Monte Carlo technique and the probability ratio method. It was found that the hydrophobic surface plays an important role in the stability of secondary structures of the polypeptides with hydrophobic side chains. For short GAAAAG peptides, the hydrophobic surface destabilizes the α helix but stabilizes the β hairpin in the entire temperature region considered in our study. Interestingly, when the surface hydrophobic strength εhpsf≥εh p, the most stable structure in the low temperature region changes from α helix to β hairpin, and the corresponding phase transition temperature increases slightly. For longer GAAAAAAAAAAG peptides, the effects of the relatively weak hydrophobic surface (εhpsf<εh p) on α-helical structures may be neglected, while the relatively strongly hydrophobic surface (εhpsf≥εh p) leads to the obvious partial helicity loss. In contrast, the stability of β structures can be enhanced significantly by the hydrophobic surface, especially by the strongly hydrophobic surface, at low and intermediate temperatures. At high temperatures, in addition to thermal fluctuations, the strongly hydrophobic surface (εhpsf>εhp) may further disturb the formation of both α-helical and β structures. Moreover, the phase transition temperature between α-helical structures and random coils significantly decreases due to the helicity loss when εhpsf>εhp. Our findings provide a basic and quantitative picture for understanding the effects of a hydrophobic surface on the conformational changes of the polypeptides with hydrophobic side chains. From an application viewpoint, the present study is helpful in developing alternative strategies of producing high-quality biological fibrillar materials and functional nanoscale devices by the self-assembly of the polypeptides on hydrophobic surfaces. © 2011 American Physical Society.

Ye H.,Central South University | Lu S.,Central South University | Lu S.,South China University of Technology
Applied Surface Science | Year: 2013

There are increasing debates on the high photocatalytic activity of TiO2 nanocrystals with exposed high-energy facets. In this paper, the effect of substrate on evaluation of the photocatalytic activity of anatase TiO2 nanocrystals with exposed {0 0 1} facets was studied. Surface-clean anatase TiO2 nanocrystals with exposed {0 0 1} facets were prepared by a microwave-assisted hydrothermal route in a Ti(OC 4H9)4-HF-H2O mixed solution (both the amount of Ti(OC4H9)4 and HF were 60 mmol). It was found that the percentage of exposed {0 0 1} facets is negatively correlated with the molar ratio of water to titanium/or fluoride (x). With increasing x from 0 to 21, the percentage of exposed {0 0 1} facets steadily decreases from 81% to 36%. Anionic dye Brilliant Red X-3B (X3B) and cationic dye Methylene Blue (MB) were used as probes to evaluate the relative photocatalytic activity of the prepared TiO2 samples. TiO2 nanocrystals with exposed 40% {0 0 1} facets at x = 15 shows the highest photocatalytic activity in degradation of MB. However, an overwhelmingly better performance of TiO2 sample with exposed 49% {0 0 1} facets at x = 9 was found among all the photocatalysts in photocatalytic degradation of X3B, reflecting the importance of substrate on evaluation the photocatalytic activity of high-energy TiO2 nanocrystals. © 2013 Elsevier B.V.

Lu X.,Beijing Jiaotong University | Ling L.,South China University of Technology
Chaos | Year: 2015

Describing coherently coupled and orthogonally polarized waveguide modes in the Kerr medium, vector bright solitons associated with positive coherent coupling are studied in this paper. Some conserved quantities and infinitely many conservation laws are computed, and the existence of Lax pair indicates the integrability of the two-coupled nonlinear Schrödinger system with positive coherent coupling. Performing the iterative algorithm of Darboux transformation, we present formulas of one-, two-, and even N-soliton solutions. With appropriate choices of the phase parameters, collision mechanisms of vector bright solitons (of single-hump, double-hump, or flat-top profiles) are displayed, which show the elastic collision under the combined influences of group velocity dispersion, self-phase modulation, cross-phase modulation, and positive coherent coupling. © 2015 AIP Publishing LLC.

Hou S.,South China University of Technology | Ou Z.,South China Normal University | Chen Q.,Nankai University | Wu B.,South China Normal University
Biosensors and Bioelectronics | Year: 2012

A novel acetylcholinesterase (AChE)/choline oxidase (ChOx) bienzyme amperometric acetylcholine biosensor based on gold nanoparticles (AuNPs) and multi-walled carbon nanotubes (MWCNTs) has been successfully developed by self-assembly process in combination of sol-gel technique. A thiolated aqueous silica sol containing MWCNTs and ChOx was first dropped on the surface of a cleaned Pt electrode, and then AuNPs were assembled with the thiolated sol-gel network. Finally, the alternate deposition of poly (diallyldimethylammonium chloride) (PDDA) and AChE was repeated to assemble different layers of PDDA-AChE on the electrode for optimizing AChE loading. Among the resulting biosensors, the biosensor based on two layers of PDDA-AChE multilayer films showed the best performance. It exhibited a wide linear range, high sensitivity and fast amperometric response, which were 0.005-0.4. mM, 3.395 μA/mM, and within 15. s, respectively. The biosensor showed long-term stability and acceptable reproducibility. More importantly, this study could provide a simple and effective multienzyme immobilization platform for meeting the demand of the effective immobilization enzyme on the electrode surface. © 2011 Elsevier B.V.

Su S.-J.,South China University of Technology | Sasabe H.,Optoelectronic Industry and Technology Development Association | Pu Y.-J.,Yamagata University | Nakayama K.-I.,Yamagata University | And 2 more authors.
Advanced Materials | Year: 2010

(Figure Presented) A serles of 1,3,5-triazine-core-containing electron-transport materials (ETMs) are reported as an undoped electron-transport layer (ETL), whose energy levels can be tuned by introducing pyridine rings on the periphery of the molecule and also orientation of nitrogen. An unprecedented low operating voltage of 2.42 V, corresponding to the emitting photon energy (hv), was achieved for the fac-tris(2-phenylpyridine) iridium (lr(PPy)3) based green phosphorescent OLEDs at 100 cd m-2 without consumption of their efficiency. Moreover, the threshold voltage for electroluminescence can be even 0.1 - 0.2 V lower than the minimum value of hv/e. © 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Li Y.,South China University of Technology
Journal of Cleaner Production | Year: 2014

Based on institutional theory and resource based view, this study seeks to examine linkages among institutional pressures, environmental innovation practices and performance. Specially, we test the moderating effect of resource commitment on the consequences of environmental innovation practices. We collected data from 148 manufacturers in Pearl River Delta, China to test the theoretical model. The statistical results reveal that institutional pressures coming from government's command-and-control instrument, overseas customer pressure and competitive pressure exert significant positive impact on environmental innovation practices, while government's economic incentive instrument and domestic customer pressure do not work. We also find environmental innovation practices have significant positive impact on firms' environmental performance, while the effect on financial performance should be through the mediating role of environmental performance. The further analysis reveals that the relationship between environmental innovation practices and financial performance is moderated by the level of resource commitment. As resource commitment increases, the financial performance yielded from environmental innovation practices will be better. © 2013 Elsevier Ltd. All rights reserved.

Wang Z.,Beijing Normal University | Dai Z.,Beijing Normal University | Gong G.,Beijing Normal University | Zhou C.,Hong Kong Baptist University | And 2 more authors.
Neuroscientist | Year: 2015

Relating the brain's structural connectivity (SC) to its functional connectivity (FC) is a fundamental goal in neuroscience because it is capable of aiding our understanding of how the relatively fixed SC architecture underlies human cognition and diverse behaviors. With the aid of current noninvasive imaging technologies (e.g., structural MRI, diffusion MRI, and functional MRI) and graph theory methods, researchers have modeled the human brain as a complex network of interacting neuronal elements and characterized the underlying structural and functional connectivity patterns that support diverse cognitive functions. Specifically, research has demonstrated a tight SC-FC coupling, not only in interregional connectivity strength but also in network topologic organizations, such as community, rich-club, and motifs. Moreover, this SC-FC coupling exhibits significant changes in normal development and neuropsychiatric disorders, such as schizophrenia and epilepsy. This review summarizes recent progress regarding the SC-FC relationship of the human brain and emphasizes the important role of large-scale brain networks in the understanding of structural-functional associations. Future research directions related to this topic are also proposed. © The Author(s) 2014.

Lim A.,City University of Hong Kong | Ma H.,Zhejiang University | Qiu C.,South China University of Technology | Zhu W.,City University of Hong Kong
International Journal of Production Economics | Year: 2013

This paper considers a single container loading problem with practical constraints that address the U.S. legal requirements stipulated in the California Vehicle Code (CVC) related to truck axle weight. The problem is computationally intractable for practical problem cases. We propose an integrated heuristic solution approach that combines a GRASP wall-building algorithm with linear integer programming models. Experiments are conducted using data generated from real cases showing the effectiveness of our approach. This work has been developed into a software component to facilitate decision makers in the industry. © 2013 Elsevier B.V. All rights reserved.

Hua B.,South China University of Technology
Natural Gas Industry | Year: 2011

This paper makes a comparative analysis of the developing trend of oil, coal and natural gas in the next two decades in terms of energy consumption, resource reserves, and carbon emission restrictions. Up till 2030 in China, the cumulative natural gas consumption will be increasing at the fastest speed and its occupation ratio among the total energy consumption will also keep on rising. Oil will be ultimately replaced by natural gas as the first position in the future primary energy structure. At such a historical period of transition toward a low carbon economy, natural gas will play a key role in energy saving and emission reduction, supporting the economic increase, peak-shaving, and decreasing the reliability of dependence on the imported oil. The wide application of CCHP and natural gas powered vehicles or boats will double the energy efficiency of the additional industries and building sector, reduce the carbon emission by 70%, and cut down 0. 1 billion tons of annual imported oil. Additionally, the CCHP and DES will guarantee the economic development with enough energy and power supply, solve the problem of 24-hour peak-shaving in electric power system, save the annual cost of several trillion Yuan of RMB, and reduce several million tons of energy consumption. Finally this paper emphasizes that the change of ideas on the reform of policies and mechanism should be highlighted at this historical period of transition toward a low carbon era.

Lin F.,Courant Institute of Mathematical Sciences | Lin J.,South China University of Technology | Wang C.,University of Kentucky
Archive for Rational Mechanics and Analysis | Year: 2010

This paper is concerned with a simplified hydrodynamic equation, proposed by Ericksen and Leslie, modeling the flow of nematic liquid crystals. In dimension two, we establish both interior and boundary regularity theorems for such a flow under smallness conditions. As a consequence, we establish the existence of global (in time) weak solutions on a bounded smooth domain in ℝ which are smooth everywhere with possible exceptions of finitely many singular times. © 2009 Springer-Verlag.

Song Q.,Tsinghua University | Liu W.,Tsinghua University | Li X.,Tsinghua University | Rao H.,China Southern Power Grid Co. | And 3 more authors.
IEEE Transactions on Power Electronics | Year: 2013

Modular multilevel converters (MMC) are considered a top converter alternative for voltage-source converter (VSC) high-voltage, direct current (HVDC) applications. Main circuit design and converter performance evaluation are always important issues to consider before installing a VSC-HVDC system. Investigation into a steady-state analysis method for an MMC-based VSC-HVDC system is necessary. This paper finds a circular interaction among the electrical quantities in an MMC. Through this circular interaction, a key equation can be established to solve the unknown circulating current. A new steady-state model is developed to simply and accurately describe the explicit analytical expressions for various voltage and current quantities in an MMC. The accuracy of the expressions is improved by the consideration of the circulating current when deriving all the analytical expressions. The model's simplicity is demonstrated by having only one key equation to solve. Based on the analytical expressions for the arm voltages, the equivalent circuits for MMC are proposed to improve the current understanding of the operation of MMC. The feasibility and accuracy of the proposed method are verified by comparing its results with the simulation and experimental results. © 1986-2012 IEEE.

Zhang L.-Z.,South China University of Technology
International Journal of Heat and Mass Transfer | Year: 2011

Hollow fiber membrane modules are widely used in various industries. The disordered nature of hollow fiber distributions in the module exhibits the existence of a fractal structure formed by the voids between the fibers. The area fractal dimension of the voids on the module cross section is obtained. Then the shell side flow distribution and convective heat and mass transfer are investigated based on the fractal theory developed. An experimental work where an air flow in the shell side is humidified by a water flow in the tube side is performed to validate the model. It is found that the model predicts the flow distribution and the heat and mass transfer deteriorations well with local data for a triangular array. With the model, friction factor and Sherwood number deteriorations which take into account of the degree of irregularity, in terms of fractal dimension, are analyzed. The results show that the higher the packing density is, the less the fractal dimension is, and the less the non-uniformity of the flow distribution is. The Sherwood and Nusselt numbers of a randomly distributed fiber module are only 1-5% of a uniformly spaced tube array. Correlations are proposed for the estimation of friction factor and Sherwood numbers considering the degree of irregularity. The predictions are also compared to the available mass transfer correlations in the literature. © 2010 Elsevier B.V. All rights reserved.

Liu R.,South China University of Technology
International Journal of Bifurcation and Chaos | Year: 2010

In this paper, we consider the generalized b-equation ut - uxxt + (b + 1)u2ux = buxu xx + uxxx. For a given constant wave speed, we investigate the coexistence of multifarious exact nonlinear wave solutions including smooth solitary wave solution, peakon wave solution, smooth periodic wave solution, single singular wave solution and periodic singular wave solution. Not only is the coexistence shown, but the concrete expressions are given via phase analysis and special integrals. From our work, it can be seen that the types of exact nonlinear wave solutions of the generalized b-equation are more than that of the b-equation. Many previous results are turned to our special cases. Also, some conjectures and questions are presented. © 2010 World Scientific Publishing Company.

Peng M.,Friedrich - Alexander - University, Erlangen - Nuremberg | Peng M.,South China University of Technology | Wondraczek L.,Friedrich - Alexander - University, Erlangen - Nuremberg
Optics Letters | Year: 2010

We report on photoluminescence of Sr2P2O7 : Bi2+ as a potential red-emitting phosphor for multichromatic light sources. If excited with blue light, photoluminescence of this compound spans the spectral range of about 600 to 760 nm. Static and dynamic spectral data reveal the presence of two distinct emission centers. Based on bond covalency and emission lifetime, luminescence can clearly be assigned to Bi2+ ions on Sr(1) and Sr(2) lattice sites, respectively. Energy transfer is observed from Bi(1) to Bi(2). Transfer efficiency, estimated from the lifetimes of the excited states, increases with increasing dopant concentration. © 2010 Optical Society of America.

Yang X.,Xian Jiaotong University | Zhou G.,Xian Jiaotong University | Wong W.-Y.,Hong Kong Baptist University | Wong W.-Y.,Shenzhen University | Wong W.-Y.,South China University of Technology
Chemical Society Reviews | Year: 2015

Phosphorescent organic light-emitting devices (OLEDs) have attracted increased attention from both academic and industrial communities due to their potential practical application in high-resolution full-color displays and energy-saving solid-state lightings. The performance of phosphorescent OLEDs is mainly limited by the phosphorescent transition metal complexes (such as iridium(iii), platinum(ii), gold(iii), ruthenium(ii), copper(i) and osmium(ii) complexes, etc.) which can play a crucial role in furnishing efficient energy transfer, balanced charge injection/transporting character and high quantum efficiency in the devices. It has been shown that functionalized main-group element (such as boron, silicon, nitrogen, phosphorus, oxygen, sulfur and fluorine, etc.) moieties can be incorporated into phosphorescent emitters and their host materials to tune their triplet energies, frontier molecular orbital energies, charge injection/transporting behavior, photophysical properties and thermal stability and hence bring about highly efficient phosphorescent OLEDs. So, in this review, the recent advances in the phosphorescent emitters and their host materials functionalized with various main-group moieties will be introduced from the point of view of their structure-property relationship. The main emphasis lies on the important role played by the main-group element groups in addressing the key issues of both phosphorescent emitters and their host materials to fulfill high-performance phosphorescent OLEDs. © The Royal Society of Chemistry 2015.

Qiu Z.-C.,South China University of Technology
Mechanical Systems and Signal Processing | Year: 2012

A flexible Cartesian manipulator is a coupling system with a moving rigid body and flexible structures. Thus, vibration suppression problem must be solved to guarantee the stability and control accuracy. A characteristic model based nonlinear golden section adaptive control (CMNGSAC) algorithm is implemented to suppress the vibration of a flexible Cartesian smart material manipulator driven by a ballscrew mechanism using an AC servomotor. The system modeling is derived to recognize the dynamical characteristics. The closed loop stability is analyzed based on the model. Also, an experimental setup is constructed to verify the adopted method. Experimental comparison studies are conducted for modal frequencies identification and active vibration control of the flexible manipulator. The active vibration control experiments include set-point vibration control responses, vibration suppression under resonant excitation and simultaneous translating and vibration suppression using different control methods. The experimental results demonstrate that the controller can suppress both the larger and the lower amplitude vibration near the equilibrium point effectively. © 2012 Elsevier Ltd.

Luo Z.-G.,South China University of Technology | Luo Z.-G.,Kansas State University | Shi Y.-C.,Kansas State University
Journal of Agricultural and Food Chemistry | Year: 2012

Acetylated waxy, normal, and high-amylose maize starches with intermediate degrees of substitution (DS) were prepared in aqueous solution with 20% (w/w) sodium hydroxide as a catalyst. The level of DS was in the order high-amylose maize starch > waxy maize starch > normal maize starch. Settling volume indicated that during the early reaction, normal maize starch swelled to a lesser extent compared with waxy and high-amylose maize starches. The settling volume of all three starches increased initially but decreased after long reaction time. Aggregation of granules was observed as DS increased. The A-type X-ray diffraction pattern of acetylated normal and waxy maize starches weakened as DS increased, whereas the diffraction peaks disappeared in acetylated high-amylose starch when DS was 0.95. Low DS promoted the swelling of the starches in water, but at high DS, the starches became more hydrophobic and the peak viscosity of acetylated starches decreased. © 2012 American Chemical Society.

Wu Z.,South China University of Technology | Goshtasby A.,Wright State University
IEEE Transactions on Image Processing | Year: 2012

Advances in image acquisition systems have made it possible to capture high-resolution images of a scene, recording considerable scene details. With increased resolution comes increased image size and geometric difference between multiview images, complicating image registration. Through Voronoi subdivision, we subdivide large images into small corresponding regions, and by registering small regions, we register the images in a piecewise manner. Image subdivision reduces the geometric difference between regions that are registered and simplifies the correspondence process. The proposed method is a hierarchical one. While previous methods use the same block size and shape at a hierarchy, the proposed method adapts the block size and shape to the local image details and geometric difference between the images. This adaptation makes it possible to keep geometric difference between corresponding regions small and simplifies the correspondence process. Implementational details of the proposed image registration method are provided, and experimental results on various types of images are presented and analyzed. © 1992-2012 IEEE.

Wang G.,South China University of Technology
Procedia Engineering | Year: 2012

Introducing the basic theory and computing process of time series forecasting based on Support Vector Regression (SVR) in details, optimizing the parameters of SVR by Genetic Algorithm (GA). Applying SVR to forecast the demand of supply chain in real data, and compared to the RBF neural network method. The result shows that SVR is superior to RBF in prediction performance. And SVR is the suitable and effective method for demand forecasting of supply chain. © 2011 Published by Elsevier Ltd.

Sun W.,South China University of Technology
Journal of Control Theory and Applications | Year: 2013

This paper studies the global robust output regulation problem for lower triangular systems subject to nonlinear exosystems. By employing the internal model approach, this problem can be boiled down to a global robust stabilization problem of a time-varying nonlinear system in the cascade-connected form. Then, a set of sufficient conditions for the solvability of the problem is derived, and thus, leading to the solution to the global robust output regulation problem. An application of the main result of this paper is also proposed. © 2013 South China University of Technology, Academy of Mathematics and Systems Science, Chinese Academy of Sciences and Springer-Verlag Berlin Heidelberg.

Yang X.,Xian Jiaotong University | Zhou G.,Xian Jiaotong University | Wong W.-Y.,Hong Kong Baptist University | Wong W.-Y.,South China University of Technology
Journal of Materials Chemistry C | Year: 2014

White polymer light-emitting diodes (WPLEDs) represent an intense research subject towards their potential applications in full-color displays, next-generation solid-state lighting sources and back-lighting of liquid-crystal displays due to their merits including low-cost fabrication, flexibility, large area and ease of construction etc. Unfortunately, WPLEDs generally show much poorer EL performance with respect to those made by the vacuum deposition strategy owing to the inherent disadvantages associated with the materials used, device structures and device fabrication processes etc., which has seriously restricted their practical applications. However, the performances of WPLEDs have been improved greatly in recent years, and can even realize some practical devices. In this review, the critical design tactics employed to achieve this goal are presented, which include developing high performance functional light emitters, maintaining a good charge injection/transport balance, introducing new functional layer, surface morphology engineering and employing novel device construction processes etc. In addition, the ongoing challenges and future perspectives of this research frontier are also highlighted. © 2014 The Royal Society of Chemistry.

Cen L.,Institute for Infocomm Research | Yu Z.L.,South China University of Technology | Ser W.,Nanyang Technological University | Cen W.,Elektrotechnik GmbH
IEEE Transactions on Antennas and Propagation | Year: 2012

A novel algorithm on beam pattern synthesis for linear aperiodic arrays with arbitrary geometrical configuration is presented in this paper. Linear aperiodic arrays are attractive for their advantages on higher spatial resolution and lower sidelobe. However, the advantages are attained at the cost of solving a complex non-linear optimization problem. In this paper, we explain the Improved Genetic Algorithm (IGA) that simultaneously adjusts the weight coefficients and inter-sensor spacings of a linear aperiodic array in more details and extend the investigations to include the effects of mutual coupling and the sensitivity of the Peak Sidelobe Level (PSL) to steering angles. Numerical results show that the PSL of the synthesized beam pattern has been successfully lowered with the IGA when compared with other techniques published in the literature. In addition, the computational cost of our algorithm can be as low as 10% of that of a recently reported genetic algorithm based synthesis method. The excellent performance of IGA makes it a promising optimization algorithm where expensive cost functions are involved. © 2011 IEEE.

Liu X.,Zhejiang University | Qiu J.,Zhejiang University | Qiu J.,South China University of Technology
Chemical Society Reviews | Year: 2015

Transfer of energy occurs endlessly in our universe by means of radiation. Compared to energy transfer (ET) in free space, in solid state materials the transfer of energy occurs in a rather confined manner, which is usually mediated by real or virtual particles, including not only photons, but also electrons, phonons, and excitons. In the present review, we discuss the recent advances in optical ET by resonance mediated with photons in solid materials as well as their nanoscale counterparts, with focus on the photoluminescence behavior pertaining to ET between optically active centers, such as rare earth (RE) ions. This review begins with a brief discussion on the classification of optical ET together with an overview of the theoretical formulations and experimental method for the examination of ET. We will then present a comprehensive discussion on the ET in practical systems in which normal photoluminescence, upconversion and quantum cutting resulted from ET involving metal ions, QDs, organic species, 2D materials and plasmonic nanostructures. Diverse ET systems are therefore simply categorized into cases of ion-ion interactions and non-ion interactions. Special attention has been paid to the progress in the manipulation of spatially confined ET in nanostructured systems including core-shell structures, as well as the ET in multiple exciton generation found in QDs and organic molecules, which behave quite similarly to resonance ET between metal ion centers. Afterwards, we will discuss the broad spectrum of applications of ET in the aforementioned systems, including solid state lighting, solar energy utilization, bio-imaging and diagnosis, and sensing. In the closing part, along with a short summary, we discuss further research focus regarding the problems and possible future directions of optical ET in solids. © The Royal Society of Chemistry 2015.

Huang J.,South China University of Technology
Journal of Nanophotonics | Year: 2016

The transient nonlinear Schrodinger equation in which the frequency is a function of time is established to describe the fast-varying field in the process of supercontinuum generation. It is solved with two methods and validated by comparing its simulation results with those of reported experiments. Based on the simulations of this extended equation, it is also demonstrated that the second-order differential of the field to longitude (z) can be ignored in the supercontinuum generation, and the additive item caused by the relationship between frequency and time will induce a homogeneous frequency shift. © 2016 Society of Photo-Optical Instrumentation Engineers (SPIE).

Lu H.L.,University of Hong Kong | Huang G.Q.,University of Hong Kong | Yang H.D.,South China University of Technology