Chengdu, China

Southwest Jiaotong University is a national key university in Chengdu, Sichuan, affiliated to the Ministry of the Education of China. The university is a member of the 211 Project and the 985 Project. Wikipedia.

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China Railway Corporation, Southwest Jiaotong University and CHANGZHOU PACIFIC Electrical POWER EQUIPMENT GROUP CO. | Date: 2015-04-20

A rolled iron core traction transformer, comprising an iron core (1); the iron core (1) is formed by splicing two symmetrical annealed iron-core closed single frames (1-1); each iron-core closed single frame (1-1) is formed by sequentially coiling continuous silicon steel sheets; the iron-core closed single frame (1-1) has two iron core column single bodies (1-1-1) having approximately semicircular cross sections; the iron core (1) has two iron core columns (1-2) thereon spliced by the iron core column single bodies (1-1-1) and having approximately circular cross sections; each iron core column (1-2) is sequentially provided with a low-voltage T winding (6), a low-voltage F winding (5) and a high-voltage winding (4) thereon from inside to outside; two sides of each high-voltage winding (4) are respectively provided with a first tapping area and a second tapping area; the first tapping area is provided with low-voltage side high-voltage tapping outgoing lines (16); the second lapping area is provided with high-voltage side high-voltage tapping outgoing lines (18); two low-voltage side high-voltage tapping outgoing lines (16) are connected together via a no-load voltage regulation switch (9); and two high-voltage side high-voltage tapping outgoing lines (18) are connected together via another no-load voltage regulation switch (9). The transformer reduces no-load loss, has a small no-load current, low noise and strong anti-short circuit capability, reduces the electrodynamic force generated by a sudden short circuit, and improves the short circuit tolerance capability of the transformer.

China Railway Corporation, Southwest Jiaotong University and Changzhou Pacific Electrical Power Equipment Group Co. | Date: 2017-04-05

A rolled iron core traction transformer, comprising an iron core (1); the iron core (1) is formed by splicing two symmetrical annealed iron-core closed single frame (1-1) ; each iron-core closed single frame (1-1) is formed by sequentially coiling continuous silicon steel sheets; the iron-core closed single frame (1-1) has two iron-core column single bodies (1-1-1),which having approximately semicircular cross sections; the iron core (1) has two iron-core columns (1-2), which have approximately circular cross section, thereon formed by splicing two iron-core column single bodies (1-1-1) ; each iron-core column (1-2) is sequentially provided with a low-voltage T winding (6), a low voltage F winding (5) and a high-voltage winding (4) thereon from inside to outside; two sides of each high-voltage winding (4) are respectively provided with a first tapping area and a second tapping area, the first tapping area is provided with low-voltage side high-voltage tapping outgoing lines (16), the second tapping area is provided with high-voltage side high-voltage tapping outgoing lines (18), two low-voltage side high-voltage tapping outgoing lines (16) are connected together with a no-load voltage regulation switch (9), and two high-voltage side high-voltage tapping outgoing lines (18) are connected together with another no-load voltage regulation switch (9).The transformer has a significant the improvement such as a reduced no-load loss, a reduced no-load current, lower noise , stronger anti-short circuitcapability, a reduced electrodynamic force generated by a sudden short circuit, and a improvement of the short circuit tolerance capability of the transformer.

Tan Y.,Civil Aviation Flight University of China | Ding F.,Southwest Jiaotong University
Proceedings of 2016 IEEE Advanced Information Management, Communicates, Electronic and Automation Control Conference, IMCEC 2016 | Year: 2016

Reliability evaluation for unmanned aerial vehicle componentscan guarantee the normal service and use of the unmanned aerial vehicle. This paper proposes anunmanned aerial vehicle components reliability evaluation method based on Markov degradation process. The method build Markov model of unmanned aerial vehicle components firstly, Combined with fault record sample to obtain the state standing time and state transfer rate, afterwards using uniform acceleration technology to solve the reliability parameters. In the case of actual use of unmanned aerial vehicle, it has carried on the simulation analysis according to the proposed method, the results show that the method can evaluate the reliability of large quantities of similar components for unmanned aerial vehicle, and it has the great significance for ensuring the normal service and use of unmanned aerial vehicle. © 2016 IEEE.

Wang Y.,Southwest Jiaotong University | Liu Z.-X.,Southwest Jiaotong University
Gao Xiao Hua Xue Gong Cheng Xue Bao/Journal of Chemical Engineering of Chinese Universities | Year: 2016

The decrease of proton exchange membrane fuel cell performance during shutdown process is mainly due to the existence of residual hydrogen in the anode side. In order to quickly eliminate residual hydrogen, two shutdown control strategies (which discharge every single fuel cell using air-cooling stack fans and auxiliary load, respectively) were proposed in this paper. Effects of three shut-down strategies including direct shut-down, overall discharging shut-down and individually discharging shut-down using auxiliary load were studied on the performance of PEMFC. The results demonstrate that the strategy proposed can shorten the time for each cell remaining under high voltage and prevent the occurrence of single cell reverse polarity during shutdown, which proves the effectiveness of the proposed strategy. © 2016, Editorial Board of “Journal of Chemical Engineering of Chinese Universities”. All right reserved.

Fei Y.,Southwest Jiaotong University | Min H.,Chengdu University of Technology
2016 1st IEEE International Conference on Computer Communication and the Internet, ICCCI 2016 | Year: 2016

Feature selection and parameters optimization is an important step in the using of SVM. In recent years, more researchers are mainly focus in feature selection and parameters optimization. However, the number of support vectors with the selected support vector subset also has an effect on classification performance of SVM. Few researchers concentrate on this area. This paper proposed a novel optimization approach which aim to select the support vector subset and feature subset simultaneously based on genetic algorithms, in optimization of while, also constantly to search the best penalty parameter C and kernel function parameters. We conduct the experiments on real-world dataset from the openly UCI Machine Learning Repository using the proposed approach and the GA-based FS technology. The experimental results show that the proposed approach can efficiently choose the optimal input features with SVM parameters and also achieve the best classification performance. Moreover, it turns out that the proposed optimization method generates a less complex SVM model with fewer support vectors. © 2016 IEEE.

Duan Y.,Southwest Jiaotong University | Duan Y.,Petrochina
IOP Conference Series: Earth and Environmental Science | Year: 2017

The gas pipeline networks in Sichuan and Chongqing (Sichuan-Chongqing) region have formed a fully-fledged gas pipeline transportation system in China, which supports and promotes the rapid development of gas market in Sichuan-Chongqing region. In the circumstances of further developed market-oriented economy, it is necessary to carry out further the pipeline system reform in the areas of investment/financing system, operation system and pricing system to lay a solid foundation for improving future gas production and marketing capability and adapting itself to the national gas system reform, and to achieve the objectives of multiparty participated pipeline construction, improved pipeline transportation efficiency and fair and rational pipeline transportation prices. In this article, main thinking on reform in the three areas and major deployment are addressed, and corresponding measures on developing shared pipeline economy, providing financial support to pipeline construction, setting up independent regulatory agency to enhance the industrial supervision for gas pipeline transportation, and promoting the construction of regional gas trade market are recommended. © Published under licence by IOP Publishing Ltd.

Chen L.,Southwest Jiaotong University | Tsai Y.-Y.,Chung Hua University
Proceedings of the IEEE International Conference on Advanced Materials for Science and Engineering: Innovation, Science and Engineering, IEEE-ICAMSE 2016 | Year: 2016

During the past forty years of rapid development in Taiwan, the urban development has reached another stage that should not only focus on the quantity but also on the quality, which is the most important issue in the regeneration of old street district in urban development. Though the old street block represents the history of urbanization and the most local lifestyle of Taiwan, the chaos of transportation system and the numerous demolition in this area during the urban renewal process can result in the graduate disappearance of the local context and history. It refers to the human five senses of sight, touch, hearing, smell, taste. The situation was that only the sight was valued while the other four senses were oversight and so were the characteristic spaces in the old street which can be necessary to be considered. This research attempts to develop a research framework that first gathers the five-sense events of the old street and then audits these events in the plan to categorize the events. Finally we can extract the five-sense spatial prototype through the categorized events. Next use the five-sense spatial prototype to analyze the old street. After mastering these spatial prototypes of the old street, we can integrate some rules to comply with and then we can carry out the urban renewal with confidence to better consider the possibility of sustaining the local context of urban environment. © 2016 IEEE.

Zhao Y.X.,Southwest Jiaotong University | Zhang Y.,Southwest Jiaotong University | He H.W.,China Academy of Railway Sciences
International Journal of Fatigue | Year: 2017

Appropriate approach, local true and/or virtual S–N relations deduced maximum likelihood approach (GMLA), is proposed for improving measurement on probabilistic fatigue limits by test data from staircase test method. The test data are distinguished as three cases, i.e. fully paired failure–survival specimens, partial paired plus individual survival specimen(s), and partial paired plus individual failure. Innovative way for deducing fatigue strength data is found by constructing physically paired local S-N relations for all test failure or survival specimens. Non-liner exponent law is introduced physically for describing the local relations under addressing the concaved character of fatigue S–N curves. The deduced data are determined by addressing physically the fatigue life for defining the test method to assure the strength data distributed orthogonally projection to the life section. Statistical parameters for fatigue limits and key element, the exponent to decide shape of the local relations/curves, are finally solved mathematically from a statistics by a maximum likelihood function for the deduced data from entire test data. Therefore, fatigue limits/strengths relative physics and math have been addressed by the present approach. Two existent approaches, Dixon–Mood approach (DMA) and Zhang–Kececioglu approach (ZKA), are reviewed together with the present approach by checking their effects of treating the test data of railway EA4T axle steel and wheel rim material of CL65 wheel steel. Applications verify that the present approach can give minimum evaluation on standard deviation and appropriate evaluation on average value for fatigue limits. While DMA and ZKA show a bigger evaluation on standard deviation and bias evaluation on average value. Basic case is that their deduced strengths do not address the concaved character and the defined fatigue life. They are not gotten from reasonable locations of local relations so to give the bias evaluation of average value. And they not distributed orthogonally to the life section so to give the bigger evaluation of standard deviations. © 2016 Elsevier Ltd

Jie Z.Y.,Southwest Jiaotong University | Li Y.D.,Southwest Jiaotong University | Wei X.,Southwest Jiaotong University
Fatigue and Fracture of Engineering Materials and Structures | Year: 2017

The paper studies the effects of artificial corrosion pits and complex stress fields on the fatigue crack growth of full penetration load-carrying fillet cruciform welded joints with 45° inclined angle. Parameters of fatigue crack growth rate of welded joints are obtained from S-N curves under different levels of corrosion. A numerical method is used to simulate fatigue crack growth using different mixed mode fatigue crack growth criteria. Using polynomial regression, the crack shape correction factor of welded joints is fitted as a function of crack depth ratios. Because the maximum circumferential stress criterion is simple and easy to use in practice, fatigue crack growth rate is modified using this criterion. The relationship of effective stress intensity factor, crack growth angle and crack depth is studied under different corrosion levels. The simulated crack growth path obtained from the numerical method is compared with the actual crack growth path observed by fatigue tests. The results show that fatigue cracks do not initiate at the edge or bottom of pits but at the weld toes where the maximum stress occurs. The artificial corrosion pits have little effect on the effective stress intensity factor ranges and crack growth angle. The fatigue crack growth rates of welded joints with pits 1 and 2 are 1.15 times and 1.40 times larger than that of the welded joint with no pit, respectively. The simulated crack growth path agrees well with the actual one. The fatigue life prediction accuracy using the modified formulation is improved by about 18%. The crack shape correction factor obtained using the maximum circumferential stress criterion is recommended being used to calculate fatigue life. © 2017 Wiley Publishing Ltd.

Lu W.,Southwest Jiaotong University | Yang Y.,Southwest Jiaotong University
Key Engineering Materials | Year: 2017

To provide reasonable guidance for CFST practical structures in design and construction, shrinkage test of concrete-filled steel tube (CFST) members in natural environments was presented. In order to acquire some knowledge regarding the influence of the interaction between the steel tube and core concrete during concrete shrinkage, ordinary concrete (OC) specimens exposed to the atmosphere were also performed in this test. The experimental results have been compared with predicted shrinkage strains obtained from the CEB-FIP1990 model, B3 model, GL2000 model, ACI 209 model. The research results show that the measured shrinkage strains of CFST specimens presents characteristics of seasonal variation under the influence of natural environments. Although expansive additive is added in the concrete mix, there is still strain difference between the steel tube and core concrete. The influence of steel ratio on the shrinkage behavior of CFST is unclear. The value of CFST shrinkage strain is about 50% of the OC shrinkage strain. For the early-age shrinkage of CFST, the predicted result by the ACI209 model is better than the other three models. The CEB-FIP1990 model is recommended to be used to predict the long-term shrinkage behavior of CFST. © 2017 Trans Tech Publications.

Jing L.,Southwest Jiaotong University | Jing L.,Xi'an Jiaotong University | Yang F.,Guangdong University of Technology | Zhao L.,Taiyuan University of Technology
Composite Structures | Year: 2017

The perforation resistance capability of clamped square sandwich panels with layered gradient metallic foam cores subjected to the hemispherical-nosed projectile impact was investigated numerically. The previous penetration tests on monolithic foam core sandwich panels were used to validate the present simulation approach, and then the deformation process, critical velocity and energy absorption of monolithic Al plate, ungraded and layered-gradient sandwich targets were studied, respectively. Influences of the strain rate and asymmetric face-sheets on the perforation resistance of the layered-gradient sandwich target were also discussed. The simulation results indicate that layered-gradient sandwich targets have the worst perforation resistance and energy absorption capability, and then the ungraded sandwich panel, and the monolithic plate is the best. For layered-gradient sandwich panels, the perforation resistance is hard to improve obviously by changing the arrangements of core-layers. Besides, the strain rate effect of materials and asymmetric face-sheets contribute to enhance the perforation resistance of layered-gradient sandwich targets only for the low-velocity penetration condition. These findings are beneficial for guiding the design and assessment of layered-gradient sandwich structures in engineering applications. © 2017 Elsevier Ltd

Chen J.,City University of Hong Kong | Ma J.,Southwest Jiaotong University | Lo S.M.,City University of Hong Kong
Simulation Modelling Practice and Theory | Year: 2017

In the past few decades, numerous ultra high-rise buildings have been erected in the metropolitan areas of many cities around the world. For the related building designers, building occupants and the governments, fire safety problem is certainly a major concern, especially after the collapse of World Trade Center in the 9/11 event. That disaster makes people reconsider ultra high-rise building evacuation strategies. Of the current strategies, using elevators in ultra high-rise buildings to assist evacuation seems to be promising in improving evacuation efficiency. To quantitatively evaluate elevator assisted evacuation process, an event-driven agent-based modeling approach is proposed in the present paper. This modeling approach could capture not only the movement characteristics of stair-using occupants but also the detailed elevator motion features. The combined effects of occupants’ and elevators’ parameters on the evacuation efficiency have been investigated. Results indicated that the model is helpful to reveal the dynamics of elevator assisted evacuation, and sometime, using elevators to move all occupants to ground safety point may not be an optimal solution. © 2017 Elsevier B.V.

Lu L.,Southwest Jiaotong University | Zhao H.,Southwest Jiaotong University
Circuits, Systems, and Signal Processing | Year: 2017

The least mean kurtosis (LMK) algorithm has been successfully applied to linear system identification. It outperforms the conventional least mean square method for Gaussian and non-Gaussian noises. The purpose of this work is to apply the LMK algorithm to active noise control (ANC) systems, i.e., to develop a filtered-x LMK (FxLMK) algorithm. The proposed FxLMK algorithm is robust against the attenuation of various noise interferences in ANC system. To further improve the noise reduction performance, a recursive sampled variance method is incorporated into the FxLMK algorithm, resulting in an improved FxLMK (IFxLMK) algorithm without significantly increasing the computational burden. Simulations in the various noise inputs show the effectiveness of the proposed algorithms. Moreover, the traction substation noise control problem is considered in our simulations, and an overall system scheme and simulation studies are conducted. Simulation results demonstrate that the IFxLMK algorithm can improve the convergence rate of adaptive filter and improve the performance of noise reduction. © 2016, Springer Science+Business Media New York.

Ye F.,Southwest Jiaotong University | Lou X.Y.,Southwest Jiaotong University | Sun L.F.,Southwest Jiaotong University
PLoS ONE | Year: 2017

This paper proposes a new support vector machine (SVM) optimization scheme based on an improved chaotic fly optimization algorithm (FOA) with a mutation strategy to simultaneously perform parameter setting turning for the SVM and feature selection. In the improved FOA, the chaotic particle initializes the fruit fly swarm location and replaces the expression of distance for the fruit fly to find the food source. However, the proposed mutation strategy uses two distinct generative mechanisms for new food sources at the osphresis phase, allowing the algorithm procedure to search for the optimal solution in both the whole solution space and within the local solution space containing the fruit fly swarm location. In an evaluation based on a group of ten benchmark problems, the proposed algorithm's performance is compared with that of other well-known algorithms, and the results support the superiority of the proposed algorithm. Moreover, this algorithm is successfully applied in a SVM to perform both parameter setting turning for the SVM and feature selection to solve real-world classification problems. This method is called chaotic fruit fly optimization algorithm (CIFOA)-SVM and has been shown to be a more robust and effective optimization method than other well-known methods, particularly in terms of solving the medical diagnosis problem and the credit card problem. © 2017 Ye et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.

Li B.,University of Sichuan | Yang H.,Southwest Jiaotong University
Computers and Mathematics with Applications | Year: 2017

In this paper, we concern over a class of the Wigner-Poisson-Xα system introduced and developed by Bao et al. (2003), Mauser (2001) and Stimming (2005), respectively. The model describes the quantum mechanical motion of particles under the influence of the nonlocal Hartree potential and a local power term (exchange potential). The existence and uniqueness of local mild solution to the n-dimensional (n=1,3) Cauchy problems are established on the space of some integrable functions whose inverse Fourier transforms are also integrable. © 2017 Elsevier Ltd.

Yin X.,Southwest Jiaotong University | Cao B.,Southwest Jiaotong University
ICHVE 2016 - 2016 IEEE International Conference on High Voltage Engineering and Application | Year: 2016

In order to better apply frequency domain spectroscopy(FDS) in assessment of generator stator insulation condition, the frequency domain spectroscopy of the stator bar insulation were tested at different temperatures. The variation law of dielectric loss factor tanδ, complex permittivity ϵ and electrical conductivity β of the bar insulation with temperature and electric field frequency were analyzed. The insulation properties of bar influenced by temperature were further discussed in this paper, a normalization method of date at different temperatures was introduced. The results show that the permittivity of the generator stator bar insulation affected by temperature is sensitive at low frequency, and the geometric capacitance C shows an exponential relationship with temperature T. ϵ'-f(T) and tanδ-f (T) have an exponential relationship with C. This study can eliminate the influence of environment temperature on FDS measurements, and makes it better to assess the state of generator stator insulation with FDS. © 2016 IEEE.

Cao G.,Southwest Jiaotong University | Cao B.,Southwest Jiaotong University
ICHVE 2016 - 2016 IEEE International Conference on High Voltage Engineering and Application | Year: 2016

Composite insulators will appear deformation under the strong wind, it makes serious stress concentration at the roots of the sheds. The roots of insulator sheds are in the state of stress fatigue under the cyclic wind load, and finally lead to shed cracks. In allusion to the problems mentioned above, with the composite insulator for overhead contact system cantilever as the object, a model of 3D computer simulation was established. This paper discussed the relationship between deformation of the sheds and stress of the roots of insulator sheds, and explored the influence of wind speed, angle of wind approach and deformation of the sheds. The research shows that On the whole, the effect of the roots of the chamfering radius on the deformation is minimal, It is not important structural parameters of wind resistance. There is a linear relationship between wind speed, stress of the roots of sheds and deformation of the sheds. When the angle of wind approach is 17°, the deformation of the sheds is biggest under same wind velocity. When the angle of wind approach is 84°, the deformation of the sheds is smallest under same wind velocity. When the lower angle of the sheds is 7°, the deformation of the sheds is smallest under same wind velocity. According to the above research results, the wind-resistant composite insulator is designed. © 2016 IEEE.

Chen X.,Southwest Jiaotong University | Li C.,Southwest Jiaotong University
ICHVE 2016 - 2016 IEEE International Conference on High Voltage Engineering and Application | Year: 2016

Condenser core which winded by oil impregnated paper was used to simulate the main insulation of high voltage bushing in laboratory condition, and aluminum foil layers was inserted in particular location to balance electric field. Accelerated thermal aging experiment were performed on condenser core to investigate the impact of insulation aging and temperature on frequency domain spectroscopy (FDS) test result of high voltage bushing. Experiment results shows that ϵ', ϵ″ and tan δ of the condenser core increase with the increasing of aging time and measurement temperature at low frequency, while have no obvious change at high frequency; With the increase of the temperature, ϵ″ increase in low frequency, the frequency point where ϵ' change rapidly shifts to higher frequency. © 2016 IEEE.

Yin X.,Southwest Jiaotong University | Cao B.,Southwest Jiaotong University
ICHVE 2016 - 2016 IEEE International Conference on High Voltage Engineering and Application | Year: 2016

To study the effect of humidity (M) on frequency domain spectroscopy (FDS) test of rotating machines epoxy/mica insulation, the stator bar was put in different humidity container and was tested with FDS. Cole-cole model was built to study the effect of humidity on FDS test of epoxy/mica insulation with the microscopic relaxation. The results show that with M increasing, ϵ' and ϵ'' of epoxy/mica insulation increase and move towards higher frequency in 10-3∼103Hz, besides, interface polarization and dipole steering polarization are strengthened and the band interfacial polarization plays a leading role gradually widens. Interfacial polarization relaxation time constant η show a linear exponential relationship with M. It can eliminate the influence of humidity on FDS test of the epoxy/mica insulation with relationship between τ1 with M in the process of data analysis, which can make it easier to diagnose the status of generator insulation with FDS technology. © 2016 IEEE.

Huang K.,Southwest Jiaotong University | Gao B.,Southwest Jiaotong University
ICHVE 2016 - 2016 IEEE International Conference on High Voltage Engineering and Application | Year: 2016

In recent years, high-speed railway represented by LanXinXian is gradually deeper into the desert area. As a result, the sand dust is a potential threat to the railway [1]. Lines in the sand-dust environment will cause friction between grain of sand and the surface of insulator, and then the surface become out of flatness, which will makes the surface of the insulator gathered a large number of charge, and the electric field distortion, which cause insulator flashover easily. This paper focus on the erosion damage and insulator flashover. Though simulation, it could be found that with the increase of wind speed, the degree of erosion rate raise as a result; the worst place that eroded appeared on the windward side of insulator's mandrel sheathed; and the erosion on the umbrella skirt is little, nearly no erosion on the leeward. Though experiment the flashover characteristics' regularity of roof insulators and its relationship can be obtained in sand-dust environment. © 2016 IEEE.

Zhou M.,Southwest Jiaotong University | Li C.,Southwest Jiaotong University
ICHVE 2016 - 2016 IEEE International Conference on High Voltage Engineering and Application | Year: 2016

In electric power industry, electrical inspection is needed for many power equipment or power lines before application or operation. Presently, the electroscopes utilized for electrical tests and measurements are almost contacted types. This would be dangerous for the work staff if the insulation of electroscope has any defects. As partial discharge (PD) always take places in those power equipment, especially in ultra-high voltage (UHV) apparatuses, partial discharge based researches about non-contact electroscope have been developed. However, due to the inconvenient for PD simulation, detection and interpretation, investigation of the non-contact electroscope is invalid in this way. Based on induction theory and sensor technology, an electrical circuit for detecting the power frequency electromagnetic filed is found in this paper. © 2016 IEEE.

Xia G.,Southwest Jiaotong University | Wu G.,Southwest Jiaotong University
ICHVE 2016 - 2016 IEEE International Conference on High Voltage Engineering and Application | Year: 2016

In order to evaluate the influence of different initial moisture contents for aging characteristics and their internal relations with other factors, this paper designed an accelerated thermal aging experiment, in which the oil impregnated paper made with different moisture content under laboratory conditions. Firstly, the samples measured results were simulated by using Matlab to obtain the fitting curve; then, through the fitting curve at different temperatures, this paper studied the impact of initial moisture contents on oil-paper insulation; finally, this paper interpreted the moisture contents on the impact of the thermal aging characteristic parameters and frequency domain dielectric properties. The research results show that the effect of moisture and temperature on oil-paper insulation aging is not a simple superposition, but mutual coordination, mutual restraint; both higher temperature and more moisture contents will increase the rate of acids, but moisture content can affect the distribution ratio of acids in oil-paper insulation; the moisture content of oil-paper insulation system have a great influence on acids in oil. In addition, we presented the frequency dielectric spectroscopy features (dielectric constant ϵtotal) for the diagnosis of moisture content and aging state, and found that ϵtotal has good relationship with moisture content. © 2016 IEEE.

Hao C.,Southwest Jiaotong University | Gao B.,Southwest Jiaotong University
ICHVE 2016 - 2016 IEEE International Conference on High Voltage Engineering and Application | Year: 2016

To research the feasibility of applying of frequency domain dielectric spectroscopy method in the state diagnosis of generator insulation condition. Dielectric dissipation factor tanδ and relative dielectric constant of test specimens of generator stator bar of different aging degrees under multi-factor accelerated aging are tested by frequency domain spectroscopy (FDS) method. And the quantitative relationship between capacitance and routine test parameters of dielectric loss tangent tanδ are built. The result shows that the frequency domain spectral curve are affected by the aging degree of test bar significantly. The values of tanδ and ϵ increase with the aging degree, especially in low frequency stage. Tanδ at characteristic frequencies with capacitance C, ϵ at characteristic frequencies with taná at power frequency of different aging periods meet the index function relation. The research results are available for reference to apply FDS to noninvasive diagnosis of generator insulation aging status. © 2016 IEEE.

Yang X.,Southwest Jiaotong University | Liu Y.,Northwestern Polytechnical University | Ma P.,Sichuan Institute of Building Research
Engineering Optimization | Year: 2017

Structural reliability analysis under evidence theory is investigated. It is rigorously proved that a surrogate model providing only correct sign prediction of the performance function can meet the accuracy requirement of evidence-theory-based reliability analysis. Accordingly, a method based on the active learning kriging model which only correctly predicts the sign of the performance function is proposed. Interval Monte Carlo simulation and a modified optimization method based on Karush–Kuhn–Tucker conditions are introduced to make the method more efficient in estimating the bounds of failure probability based on the kriging model. Four examples are investigated to demonstrate the efficiency and accuracy of the proposed method. © 2017 Informa UK Limited, trading as Taylor & Francis Group

Zhou G.,Southwest Jiaotong University | Xu J.,Southwest Jiaotong University | Sha J.,Southwest Jiaotong University | Jin Y.,Southwest Jiaotong University
8th International Conference on Power Electronics - ECCE Asia: "Green World with Power Electronics", ICPE 2011-ECCE Asia | Year: 2011

Valley V2 control technique for switching converters is proposed in this paper. By utilizing output voltage ripple as pulse-width modulation ramp and valley voltage of output voltage ripple as additional control variable, valley V2 control technique provides faster load transient response than conventional current-mode control techniques. Steady-state and transient performances of switching converters with valley V2 control, peak V2 control, and current-mode control are compared and verified by experimental results. © 2011 IEEE.

Alexandropoulos G.C.,Huawei | Mathiopoulos P.T.,National and Kapodistrian University of Athens | Fan P.,Southwest Jiaotong University
International Conference on Signal Processing Proceedings, ICSP | Year: 2017

In this paper, we analyze and evaluate the performance of multibranch scan-and-wait combining (SWC) receivers over arbitrarily correlated and not necessarily identically distributed Nakagami-m fading channels. A fast convergent infinite series representation for the SWC output signal-noise ratio (SNR) is firstly presented. This expression is then used to obtain analytical expressions in the form of infinite series for the average error probability for integer values of m as well as the average number of paths estimation and average waiting time (AWT) of multibranch SWC reception for arbitrary values of m. The validity of the analytical expressions has been verified via comparisons with equivalent computer simulations. It has been shown that, at the expense of a negligible AWT, the average error probability performance of SWC receivers is always superior to that of switched-and-examine combining receivers and, in certain cases, to that of maximal-ratio combining receivers. © 2016 IEEE.

Song H.,Southwest Jiaotong University | Fang X.,Southwest Jiaotong University | Fang Y.,University of Florida
IEEE Wireless Communications | Year: 2016

The shortage and congestion of lower spectra motivate the exploration of the broadband and underutilized mmWave to be used in future public mobile communications, and subsequently future HSR mobile communications, which has the potential to provide multi-gigabit rate radio access for train passengers. However, due to the inferior propagation characteristics of mmWave and particularity of HSR scenarios, there are many design challenges ahead. In this article, we tackle those challenges by developing technical solutions for mmWave broadband HSR systems. We first propose feasible multiple access techniques and frame structures based on OFDM and SC communications, respectively. We then present promising train-trackside network architectures based on different MIMO techniques, including BF and SM, which have been viewed as the key enabling technologies to realize mmWave communications in outdoor environments. Moreover, we discuss the inherent defects of each architecture and offer the corresponding solutions or recommendations. Finally, we conduct performance evaluation, and discuss the advantages and disadvantages of the proposed architectures. We hope this article will stimulate further research on the innovative use of mmWave in high-speed rail systems. © 2002-2012 IEEE.

Xiao S.,HIGH-TECH | Xiao S.,Southwest Jiaotong University | Xiao S.,University of Wollongong | Guo W.D.,University of Wollongong
Proceedings of the Institution of Civil Engineers: Geotechnical Engineering | Year: 2017

An anchored sheet wall is commonly used in retaining deep excavations. Anchor force is one of the critical design parameters in practice. Based on the kinematical admissible failure mechanism, a limit analysis approach to determine the anchor force is presented. The explicit formula for the anchor force is given, which makes it easy to calculate using a simple calculation program such as MS Office Excel. Anchor force is mainly influenced by seven parameters: the internal friction angle; cohesion of the soil; wall friction angle; surcharge on the ground surface; dip angle of the anchor; penetration depth of the wall; and depth from the anchor force action point on the wall to the ground surface. The relevant quantitative calculation can be performed by the proposed method. In addition, the design anchor force under a specified design safety factor and the anchor forces of multiple rows of anchors are also illustrated in this paper. To verify that the method is reasonable, the predicted and measured anchor forces are compared in two classical soil-nailed wall experiments. The result shows that the presented method is applicable. © 2017, ICE Publishing. All rights reserved.

Zhou J.,Sichuan Normal University | Li J.,Southwest Jiaotong University | Guo P.,Guiyang University | Lin X.,Southwest Jiaotong University
Computers and Industrial Engineering | Year: 2017

CT department is an appointment based service system. All patients except emergency patients should be scheduled in advance. Regular patients arrive on time. Emergency patients arrive randomly and get non-preemptive priority. So the direct waiting time of regular patients should be explicitly described. The unit direct waiting cost gradually increases with the previous waiting time. On the one hand, too many regular patients will increase the direct waiting cost for them and overtime cost for medical resources. On the other hand, too few regular patients will cause idling of medical resources and penalty for delaying regular patients’ requests. So a reasonable reservation level should be determined in advance. The booking problem is modeled as a finite horizon Markov decision process. Some booking limit structures are given to improve the total expected reward. The numerical analysis shows that our policies are much better than the policy currently employed. © 2017 Elsevier Ltd

Dong Y.H.,Southwest Jiaotong University | Zhang Y.F.,Southwest Jiaotong University | Li Y.H.,Southwest Jiaotong University
Composite Structures | Year: 2017

The current paper is concerned with the micro-scale laminated composite Euler-Bernoulli beams under the hygrothermal environment. The aim is mainly focused on the static and dynamical responses of micro-scale beams under consideration in both prebuckling and postbuckling cases. Meanwhile, the mechanism how temperature and hygrothermal concentration affect the critical buckling load is discussed. The material properties are considered to be temperature- and hygroscopic concentration-dependent. And the hygrothermal deformation caused by both variations in temperature and hygroscopic concentration is taken into account. The modified couple stress Euler-Bernoulli beam model involving geometric nonlinearity due to the mid-plane stretching is adopted. Then, an analytical formulation of postbuckling and buckling vibration is derived as a function of the external compressive axial load. Exact solutions for the critical buckling load, the postbuckling configuration and the natural frequency of vibration around the buckling configuration of the beam with various boundary conditions are investigated. © 2017

Wei X.,Southwest Jiaotong University | Xiao L.,Southwest Jiaotong University | Pei S.,Colorado School of Mines
International Journal of Fatigue | Year: 2017

Specimens testing and finite element analysis were conducted to investigate the fatigue performance of cope-hole details in welded integral joints of a steel truss bridge. A recommended nominal stress S-N curve of cope-hole details was obtained based on the evaluation of existing experimental results and comparison of different design specifications. The fatigue strength of the cope-hole details was evaluated via structural hot spot stress approach, which showed that the fatigue strength for the cope-hole details approaches that for FAT80. The effect of load type on local stress distribution was also identified by finite element parametric analysis. A simple equation was then proposed to estimate the stress concentration factor of cope-hole details in the tension member. © 2017 Elsevier Ltd

Wang B.,Southwest Jiaotong University | Tang J.,Chengdu University of Technology
Proceedings - 2016 International Conference on Information System and Artificial Intelligence, ISAI 2016 | Year: 2016

In order to help E-commerce enterprises to build E-commerce cloud platform with cloud computing, this article mainly discussed about application of cloud computing in E-commerce. It analyzed the relevant technology of the cloud computing and put forward E-commerce application mode on the basis of cloud computing combining with the current present situation and advantages of the development of electronic commerce. The results were beneficial for E-commerce enterprises getting a healthy development. © 2016 IEEE.

Wei K.,Southwest Jiaotong University | Yuan W.,Tongji University
Proceedings - 2016 International Conference on Smart City and Systems Engineering, ICSCSE 2016 | Year: 2016

Performance-based design requires consideration of environmental conditions at recurrence periods well beyond those of current practice, when structural damage is expected and connections are likely to behave inelastically. Performance-based design considers both the occurrence and consequence of structural damage caused by extreme conditions and could improve the performance of offshore structures. This paper assesses the post-elastic behavior and ductility of common connection details for offshore jacket structures based on a survey of experiments and empirical joint models and on nonlinear finite element analyses. The assessment includes common connection detailsunder tension, compression, and bending. The prediction of the inelastic load-deformation response, based on MSL and API, two empirical joint models in the structural analysis program, USFOS, is comparedto experiments. As an illustrative example to demonstrate the performance assessment capabilities of this approach, a pushover analysisis carried out for anoffshore jacket structure supporting a wind turbine andsubjected to extremewind and wave loading. © 2016 IEEE.

Li B.,Southwest Jiaotong University
Applied Computational Electromagnetics Society Journal | Year: 2017

A novel time reversal detection (TRD) algorithm for noise suppression is presented. The targets can be located accurately by analyzing the crosscorrelation character of TR echo signals received by subarrays. Compared with conventional TR algorithm, the performance of proposed method is superior, especially under low signal-to-noise ratio (SNR) condition. © ACES.

Luo Y.,Southwest Jiaotong University | Huang G.,Southwest Jiaotong University
Journal of Structural Engineering (United States) | Year: 2017

The prediction of the extreme value of the wind pressure receives significant attention from the wind engineering community. However, the correlation among extreme wind pressures associated with different locations on the building surface is less addressed. In this study, the characterization of the dependence structure of extreme wind pressures and its application to roofing damage estimation are presented. First, three methods to model the dependence structure of extreme wind pressures, including multivariate extreme value theory, copula function, and Nataf transformation, are reviewed. Then, the asymptotic property of the bivariate non-Gaussian random vector will be established and the partial correlation for the data within finite duration is discussed. Furthermore, the dependence structure and asymptotical properties of extreme wind pressure coefficients are investigated based on the very long wind tunnel data. The correlation of extreme pressures considering the randomness of the annual maximum mean wind speed is also addressed. Finally, the application of the correlation of extreme wind pressures on the damage estimation for the asphalt shingle roofing is discussed. © 2016 American Society of Civil Engineers.

Zhao C.,Southwest Jiaotong University | Wang P.,Southwest Jiaotong University
Proceedings of the Institution of Mechanical Engineers, Part F: Journal of Rail and Rapid Transit | Year: 2017

The design and construction of a complex damping layer for rails is presented in this paper. A numerical procedure for the calculation of the loss factor of a compound track model using this treatment was developed. Through this procedure, guidelines on the selection of the optimal material and configuration among the commercially available and technologically feasible options were formulated. A vinyl ester resin-interpenetrating polymer network was chosen as the viscoelastic material for the damping layer, polyurethane epoxy resin as the material for the extra layer, and 3Cr13Mo steel as the material for the constraining layer. This study culminated in the construction of a prototype and the evaluation of its performance in the laboratory. Laboratory measurements on track demonstrated that the proposed damping approach can effectively mitigate rail vibration and noise radiation over the frequency range between 12.5 and 4000 Hz. The glue developed in this work was found to be highly reliable and efficient in reducing noise. © IMechE 2016.

Zhou E.,Southwest Jiaotong University | Hao L.,Southwest Jiaotong University
Chinese Journal of Electronics | Year: 2017

The detection problem for the Multipleaccess Spatial modulations (M-SM) is investigated in this paper, where multiple transmitters adopting spatial modulation communicate to the receiver at the same time. The optimal Maximum-likelihood (ML) detection suffers from the high computational complexity, while Sphere decoding (SD) can not reduce the complexity effectively because of the multiple active antennas in M-SM. In order to avoid the high complexity, a Space-alternating generalized expectation-maximization (SAGE) algorithm aided List-projection (S-LP) detector is proposed and applied to M-SM systems. The received signal vector is firstly projected onto the subspaces spanned by the columns of channel matrices corresponding to the possible active antennas. Then some combinations of antenna indices with the largest projections are selected as candidate index sets, based on which, a modified SAGE algorithm is applied to update the candidate symbols. Both analysis and simulation results show that the proposed S-LP detector achieves a near-optimum performance with a significantly reduced complexity compared with ML and SD detection. © 2017 Chinese Institute of Electronics.

Hu Q.,Neijiang Normal University | Li C.,Southwest Jiaotong University
Optics Communications | Year: 2017

The effective couple of the space light into the optical fiber is the key point of the free-space optical communication. In order to solve this problem, the novel tapered optical fiber head is proposed. The special tapered structure could improve coupling efficiency through expanding the light receiving area. In order to study its coupling characteristics, the longitudinal propagation constant of the connector is expanded by Taylor series according to the wave theory. And the approximate solution of the power distribution is obtained. Then, the coupling efficiency measurement experiment with the tapered connectors and the conmmon connector is finished. The experimental result is consistent with the theoretical analysis basically. This work provides a theoretical reference for the design of the new tapered connector, which could be adopted in the free-space optical communication. © 2017 Elsevier B.V.

Wang H.,Southwest Jiaotong University | Feng Q.,Southwest Jiaotong University
Bandaoti Guangdian/Semiconductor Optoelectronics | Year: 2017

An oscillator with the function of frequency extension was proposed to suppress the electromagnetic interference(EMI) problem in LED driver. With the clock frequency modulated by frequency extension technology, EMI can be restrained effectively, and two working modes of frequency-extension mode(FEM)and fixed frequency mode(FFM)can be choosen, which drifts little across temperature. Process simulations based on 0.18 μm BCD show that the clock was extended 6.09% up and down the central frequency of 558 kHz in a period of 57.8 μs, and EMI power reduces by 12 dB. Due to its inhibition of EMI, the circuit was suitable for LED driver power supply that requires higher electromagnetic compatibility. © 2017, Editorial Office of Semiconductor Optoelectronics. All right reserved.

Li Y.-D.,Sichuan University of Science & Engineering | Yang Y.-R.,Southwest Jiaotong University
Jisuan Lixue Xuebao/Chinese Journal of Computational Mechanics | Year: 2017

In this paper, the period motion of the Mathieu-Duffing oscillator is investigated by the homo-topy analysis method. The procedures of the solution of the period-1 and period-2 are presented. The period solutions are obtained by solving the nonlinear algebraic equations. Stability of the period motion is judged by the Floquet theory. The phase portraits of period solution obtained by the homotopy analysis method agree well with those obtained by the numerical time-integration method. © 2017, Editorial Office of Chinese Journal of Computational Mechanics. All right reserved.

Mao J.,Southwest Jiaotong University | Jiang Y.,Power China Chengdu Engineering Corporation Ltd
Tiedao Xuebao/Journal of the China Railway Society | Year: 2017

A method to calculate the settlement of pile foundation based on the results of vertical static load test of single pile and the elastic theory method was presented. In the method, the settlement of every pile due to its own vertical load was determined by the settlement-load curve of vertical static load test, while the settlement caused by other piles was calculated with the elastic theory method based on the test result of side friction curve and toe force of pile. Tentative calculation was performed on the different vertical forces of each pile to find out the solution. that met the equilibrium equation of pile cap and the coordination conditions of the settlement of each pile. Following the theory, corresponding calculation formulae were constructed and calculation program was compiled. Finally, the settlement of the pile foundation of a bridge was calculated with the method and the better agreement of the results between the calculation and in-situ measurement proved the feasibility and rationality of this method. © 2017, Editorial Office of Journal of the China Railway Society. All right reserved.

Xue Q.,Southwest Jiaotong University | Fang X.,Southwest Jiaotong University
Dianzi Yu Xinxi Xuebao/Journal of Electronics and Information Technology | Year: 2017

As the substantial growth of data traffic over the past few years, the deployment of cellular base stations tends to be smaller and denser which puts forward higher requirements for backhaul techniques. In this study, WiFi is taken as a backhaul technique in 5G networks, and then a high-speed synchronous backhaul solution is proposed with aggregation of multiple WiFi channels of which the spectrum is non-continuous. Although IEEE 802.11n/ac can achieve channel aggregation with static/dynamic channel bonding scheme, the spectrum of these channels must be continuous. Moreover, static channel bonding is not flexible enough and dynamic channel bonding rarely has chance to be implemented when devices are deployed densely. The proposed solution can not only extend transmission bandwidth and improve network capacity of 5G backhaul networks, but also overcome defects of channel bonding in 802.11n/ac. Both analytical results and simulations show that the performance of the proposed solution is better than the traditional channel bonding and it can reduce adjacent channel interference among multiple channels in 5G backhaul networks. Meanwhile, the effectiveness and feasibility of the proposed solution are proved by the prototype verification system. © 2017, Science Press. All right reserved.

Jiang Y.-S.,Southwest Jiaotong University | Luo X.-L.,Southwest Jiaotong University
Chang'an Daxue Xuebao (Ziran Kexue Ban)/Journal of Chang'an University (Natural Science Edition) | Year: 2017

In order to solve the problem that existing accessibility study did not consider the quantitative relationship between accessibility and demand, and ignored the location requirements of the initial and terminal stations, this paper proposed the concepts of generalized accessibility and accessibility strength index. On this basis, an accessibility optimization model of transit network was introduced according to the planning fixed stop locations and line numbers, which took the best matching degree between demand and accessibility and the highest value of accessibility as objective and considers the location requirements of the initial and terminal stations. Genetic algorithm was proposed to solve this model, and the algorithm and model were verified through an example. The results show that the matching degree between demand and accessibility increases by 1.57% when taking the matching degree relationship between demand and accessibility into consideration. In addition, demand and accessibility of the optimized network meet the location requirements. It is indicated that the matching degree and the proportion of travel without transfer can be improved, and passengers travel can be more convenient when considering the relationship between accessibility and passenger flow when the transit network be planned. Meanwhile, according to practical location requirements of initial and terminal stations during the process of transit network planning, the constraint conditions of initial and terminal stations planning should be added, which can make the final optimized network combine with practice. The research results propose an auxiliary decision-making for transit network planning and optimization, which considers travel demand and the location requirements of initial and terminal stations and makes the optimized result meet the practical requirements. © 2017, Editorial Department of Journal of Chang'an University (Natural Science Edition). All right reserved.

Song S.,Southwest Jiaotong University | Qian Y.-J.,Southwest Jiaotong University | Wu G.,Nanjing Southeast University
Gongcheng Lixue/Engineering Mechanics | Year: 2017

In order to consider the impacts of seismic demand dependence among structural components in the seismic fragility analysis of bridge system, a mixed Copula function is constructed by using Bayesian Model Average method, and then the dependence structure is separated from the marginal distribution functions of components. In combination with incremental dynamic analysis, the fragility curves and joint distribution functions of piers and bearings are developed. And a method for calculating the fragility of bridge system is proposed, which takes the seismic demand dependence among structural components into consideration. The results indicate that mixed Copula function can accurately depict the asymmetric dependence between the upper and lower tail distributions of the seismic demands of bridge components and simplify the modeling procedure of joint probability distribution function. A comparison between the system fragility curves obtained by the proposed method and those derived using Monte Carlo method shows good agreement. In addition, the computational efficiency is significantly improved by the mixed Copula function method because it significantly reduces the number of numerical samples. © 2017, Engineering Mechanics Press. All right reserved.

Xu Y.-D.,China Railway Eryuan Engineering Group Co. | Yao L.-K.,Southwest Jiaotong University
Journal of Railway Engineering Society | Year: 2017

Research purposes: To propose the cognition about the special Geo-environmental problems along the Sichuan-Tibet Railway and the concise key points of tackle hard-nut problems in science and technology. To provide the science and technology support for the successful building and safe operation of the Sichuan-Tibet Railway. Research conclusions: The junctional zone of Gangdise-Nyenchen Tanglha active continential margin and northern Himalayan fold belt, is a region in which has never been built any railways before, facing the specific Geo-environmental problems such as, inner dynamic effect of the Yarlung Zangbo suture zone, glacier lake outburst in the maritime glacier zones and glacial debris flow, etc. The Sichuan-Tibet Railway passes through three major suture zones, including the Yarlung Zangbo suture zone, so we need to pay attention to influence on the Sichuan-Tibet Railway affected by the big earthquakes occurred on the Himalayan arc, and suggest carrying out the study on crustal stress, measuring ground temperature with the antecedent project. To the problems of glacier lake outburst in the maritime glacier zones and glacial debris flow, study on the basic theory of formation mechanism, motion feature should be enhanced, and the strategy of higher elevation design to avoid the damage of valley disaster chain should be studied as well. © 2017, Editorial Department of Journal of Railway Engineering Society. All right reserved.

Xu J.,Southwest Jiaotong University | Gao B.,Southwest Jiaotong University
ICHVE 2016 - 2016 IEEE International Conference on High Voltage Engineering and Application | Year: 2016

To study the influence of aging on time dielectric spectroscopy, the polarization/depolarization current method in time domain dielectric response technique is used for the aging state of generator insulation. Therefore, a multi-factor test is carried out for stator bars and the polarization/depolarization current is tested for stator bars after different aging time. Meanwhile, the influence of different aging time on the dielectric properties of generator insulation is analyzed and the characteristic parameters for aging are presented. The results shows that, the polarization and depolarization current curves move above to the left with the increase of aging time. The depolarization charge quantity is sensitive to the aging state of generator insulation and there is a exponential relationship between the depolarization charge quantity and test time, therefore, the depolarization charge quantity can be used to predict the aging state of generator insulation. © 2016 IEEE.

Gao T.,Southwest Jiaotong University | Gao B.,Southwest Jiaotong University
ICHVE 2016 - 2016 IEEE International Conference on High Voltage Engineering and Application | Year: 2016

In order to predict the failure rate of power substation in service and improve the safety and reliability of the equipment, the author studied the cumulative failure rule of the substation equipment, also analyzed the development process of the equipment failure based on the combination of the two steps of the update process model. The overall construction of the smart grid and the continuous accumulation of power data have provided the basis for the evaluation of the operation status of the substation equipment, it is feasible and significant for the power system to predict the failure rate of the power plant. In this paper, the method of median filter is used to preprocess the initial fault data and the feature point detection method is used to determine whether there is a boundary point of the forecast interval. Then, the author introduces the two concepts of 'fault demarcation point' and 'failure data partition' and establishes the phased fitting model based on grey linear regression combination model to analogue the trend of the failure rate of substation equipment. The results show that fault demarcation point and failure data partition are both conducive to improving the accuracy of substation equipment failure prediction, specifically, the relative error rate of improved model is 3.59% lower than the gray linear regression model and also 3.91% lower than the fault forecast model based on M-R algorithm, fitting effect of optimization model is better than others. Also shows that the improved power equipment failure rate prediction model has good feasibility, which could provide the advanced theory basis for field substation equipment fault prediction. © 2016 IEEE.

Chen Z.,Southwest Jiaotong University | Li C.,Southwest Jiaotong University
ICHVE 2016 - 2016 IEEE International Conference on High Voltage Engineering and Application | Year: 2016

Dielectric response used is usually an important method to describe the properties of electrical insulating materials. Dielectric response can be determined accurately through time and frequency domain measurements. Polarization and depolarization current measurements as a method of time domain measurement, can reflect the characteristics of the dielectric insulation sensitively. Thusthis method can qualitatively assess the insulation of the generator. There is variety of factors to affect the characteristics of generator insulation, such as mechanical stress, surface contamination, ambient conditions such as humidity and temperature. To study the impact of humidity on epoxy-mica-glass insulation, the insulation samples were exposed to the different humidity for 5 days. And then polarization and depolarization current were recorded, the relaxation charge quantity and depolarization charge quantity were calculated through extended Debye model. The result shows that insulation samples with different environmental humidity have great effect on the curves of polarization and depolarization current. Along with the relative humidity increasing, the polarization and depolarization current increase. The relaxation charge quantity and depolarization charge quantity increase with relative humidity increasing. Thus humidity has great influence on epoxy-mica-glass insulation, and humidity should be noticed when we do the experiments. © 2016 IEEE.

Peng K.,Southwest Jiaotong University | Gao G.,Southwest Jiaotong University
ICHVE 2016 - 2016 IEEE International Conference on High Voltage Engineering and Application | Year: 2016

Due to the increase of the train velocity, the pantograph-catenary arc occurs even more frequently, which results in severe erosion on the pantograph pan and the catenary wire. This leads to a serious threat to the normal operation of the pantograph-catenary system. As the level of the arc erosion has a close relationship with its energy, it is necessary to study the influencing factors and suppression means of the pantograph-catenary arc energy. In this paper, based on the actual working conditions of the simple catenary wire-supported overhead contact system, the calculations of the simulation parameters of the traction network and the load was carried out respectively. Based on the general modules provided by Sim Power System toolbox of MATLAB/SIMULINK, the model of the traction power supply system to produce arc is established. With the help of MATLAB/SIMULINK, it is also finished to calculate and analyze the change laws of the pantograph-catenary arc voltage and current under different influencing factors, mainly including the power factor and the traction current. It is found that the pantograph-catenary arc energy increases in index with the increase of the traction current, and the pantograph-catenary arc energy decreases with the increase of the power factor. At the same time, the pantograph-catenary arcing test system has been used to study the change laws of the pantograph-catenary arc voltage and current under different power factors and traction currents, which proved the simulation above to be effective and correct. This experiment also studied the influence of different traction currents and power factors on the average pantograph-catenary arc duration respectively. The results showed that the average pantograph-catenary arc duration has an approximate index relation with the traction current, and the arc duration of inductive load is longer than that of capacitive load apparently. © 2016 IEEE.

Cao Y.,Southwest Jiaotong University | Luo X.,Southwest Jiaotong University
Xitong Gongcheng Lilun yu Shijian/System Engineering Theory and Practice | Year: 2016

The optimal market penetration under maximum information benefit was discussed in this paper. A taxi demand function with Cobe-Douglas form was constructed to describe the social welfare of the different groups who apply taxi-hailling applications or not with the taxi-hailling applications efficiency parameter. Then the relationship between the vacancy mileage and the loading mileage was analyzed when the maximal social welfare was attained. On that basis, the information benefit could be defined by different value of social welfare of two groups. Finally, a market penetration model was constructed with consideration of information benefit, and the optimal market penetration was determined. Taking a network in Chengdu as an example, the result showed that the optimal market penetration was obtained from 40.1% to 45.5% under the maximal information benefit, and marginal revenue of taxi-hailing applications decreased with the growth of loading mileage. This paper could provide the basis for decision-making and references for relevant departments to improve or control the taxi-hailing applications in urban taxi operation networks. © 2016, Editorial Board of Journal of Systems Engineering Society of China. All right reserved.

Cai L.,Southwest Jiaotong University | He Y.,Wuhan University
Journal of the Franklin Institute | Year: 2017

The traditional energy-shaped method of Port-Hamiltonian system that is based on solving partial differential equations influences the accuracy and realizability of controller. To overcome those defects, a new energy-shaped method based on the cyclo-passivity is proposed to avoid solving partial differential equations. Due to the proposed method, the exponential stability of Port-Hamiltonian has been worked out. Besides that, a relationship between the guaranteed cost control and dissipation is established for the Port-Hamiltonian system, which presents an explicit form of dissipative energy. At last, examples show the validity of the proposed contents. © 2017 The Franklin Institute

Zhao J.,Southwest Jiaotong University | Zhao J.,Virginia Polytechnic Institute and State University | Wang Z.,Iowa State University | Chen C.,Argonne National Laboratory | Zhang G.,Southwest Jiaotong University
IEEE Transactions on Power Systems | Year: 2017

This letter presents a robust voltage instability predictor using local noisy PMU measurements. A robust recursive least squares estimation is proposed to mitigate the impacts of gross PMU measurement errors on estimating the bus impedance and the Thevenin equivalent impedance used for voltage stability analysis. Numerical results on the IEEE 39-bus system validate the effectiveness and robustness of the proposed method. © 1969-2012 IEEE.

Jia Y.,Southwest Jiaotong University | He Z.,Southwest Jiaotong University | Liao K.,Southwest Jiaotong University
IET Generation, Transmission and Distribution | Year: 2017

Electromechanical modes estimated from ambient wide area measurement systems measurements are often used as a basis for system dynamic security assessment. It is therefore important to know the accuracy of the mode estimates. There are two interesting phenomena widely reported in ambient mode estimation: (i) the accuracy of the mode parameter estimates improves under the lighter damping conditions and (ii) the frequency estimates are more accurate than the damping ratio estimates. This study aims to systematically investigate the estimation accuracy of ambient mode analysis. An analytical differentiation-based perturbation method is presented to examine the variance propagation along the mode estimation procedure. Monte Carlo simulations in the two-area system are carried out to analyse the influences of varying the mode parameters on the estimation accuracy of the inter-area mode, in which the estimated variances are served as quantitative measures of the accuracy analysis. In addition, theoretical explanations for the observations in ambient mode estimation are also provided as a supplementary. The investigations and discussion of the estimation accuracy are of value for yielding insight into the variability of the mode estimates under ambient conditions. © The Institution of Engineering and Technology 2016.

Cao Y.,University of Central Florida | Gao Y.,Southwest Jiaotong University | An L.,University of Central Florida
Journal of the American Ceramic Society | Year: 2017

The electric behaviors of both free-carbon phase and ceramic phase in polymer-derived amorphous silicoaluminum oxycarbide were studied by impedance spectroscopy. The results revealed that the resistance of both ceramic phase and free-carbon phase are similar to each other and decreased with pyrolysis temperature. Meanwhile, the ceramic phase showed higher capacitance than the free-carbon phase. With increasing pyrolysis temperature, the capacitance of the ceramic phase drastically decreased, but that of the free-carbon phase remained similar. Each phase exhibited a relaxation process, which moved to higher frequency with increasing pyrolysis temperature. The results are correlated with the structural evolution of the two phases. © 2017 American Ceramic Society.

Bouraima M.B.,Southwest Jiaotong University | Qiu Y.,Southwest Jiaotong University
Journal of Traffic and Transportation Engineering (English Edition) | Year: 2017

The present study attempts to investigate the effect of moisture conditioning on the indirect tensile strength (ITS) of cold recycled mixture with bitumen emulsion. Firstly, samples were prepared using a Superpave gyratory compactor. They were hence conditioned using moisture induced sensitivity tester (MIST) device. Factorial design was carried out considering four factors each at two different levels. These factors were specimen thickness, air voids content, pressure and number of cycles. In the MIST device, samples are cyclically subjected to water pressure through the sample pores. The MIST conditioned samples were tested for indirect tensile strength. The analysis of two-level full-factorial designed experiments revealed that all four factors have a negative effect on tensile strength of cold recycled mixture with bitumen emulsion. Specimen thickness was the most significant factor affecting the tensile strength followed by air voids content. In two-factor interaction, specimen thickness-number of cycles, air voids content-pressure, and pressure-number of cycles were significant. The most significant three-factor interaction was specimen thickness-pressure-number of cycles. The results from the study suggest that in measuring tensile strength, the appropriate specimen thickness and air voids content should be selected to quantify the representative tensile strength for in-situ conditions. © 2017 The Authors.

Li Y.,Southwest Jiaotong University
Civil Engineering and Urban Planning IV - Proceedings of the 4th International Conference on Civil Engineering and Urban Planning, CEUP 2015 | Year: 2016

This paper explains an intelligent campus vehicle management system for Chinese universities. Based on the principles of man-machine engineering and interactive design, utilizing systemic analysis, the system is built to target vehicle management deficiencies with regressive access control administration, such as traffic jams and long line-ups at campus entrances and exits. The object of this study on the access control administration was the Southwest Jiaotong University. This system will not only reduce the labor intensity of the public security workers on the campus by integrating automation and intelligence into the pay parking system, but will also decrease traffic jams by expediting the payment process. Additionally, it will increase the elements of "humanization" and add a "sense of warmth" to the management system, thus better supporting the humane atmosphere of the campus. The system provides a good reference for the design of university campuses. © 2016 Taylor & Francis Group, London.

Song S.,Southwest Jiaotong University | Qian Y.-J.,Southwest Jiaotong University
Civil Engineering and Urban Planning IV - Proceedings of the 4th International Conference on Civil Engineering and Urban Planning, CEUP 2015 | Year: 2016

The finite element models of landscape covered bridges with and without upper building structures and models with node qualities simulating upper building structures were established accounting for uncertainties of ground motions and structures. Seismic fragility curves of the three models were developed using nonlinear time history analysis method and the impacts of upper building structures on bridge seismic performance were assessed. The results show that: in the earthquake, the upper building structures increased the seismic demands of pier and bearing as well as the seismic vulnerability of landscape covered bridges, especially under severe and completely damaged states. Therefore, the effects of upper building structures must be accurately assessed in the seismic design or vulnerability assessment of landscape covered bridge structures. © 2016 Taylor & Francis Group, London.

Wang H.,Southwest Jiaotong University | Yang Y.,Southwest Jiaotong University | Li T.,Southwest Jiaotong University
Proceedings - IEEE International Conference on Data Mining, ICDM | Year: 2017

Real-world datasets often have representations in multiple views or come from multiple sources. Exploiting consistent or complementary information from multi-view data, multi-view clustering aims to get better clustering quality rather than relying on the individual view. In this paper, we propose a novel multi-view clustering method called multi-view concept clustering based on concept factorization with local manifold regularization, which drives a common consensus representation for multiple views. The local manifold regularization is incorporated into concept factorization to preserve the locally geometrical structure of the data space. Moreover, the weight of each view is learnt automatically and a conormalized approach is designed to make fusion meaningful in terms of driving the common consensus representation. An iterative optimization algorithm based on the multiplicative rules is developed to minimize the objective function. Experimental results on nine reality datasets involving different fields demonstrate that the proposed method performs better than several state-of-The-Art multi-view clustering methods. © 2016 IEEE.

Zhang S.,Southwest Jiaotong University | Zhang J.,Southwest Jiaotong University | So H.C.,City University of Hong Kong
Signal Processing | Year: 2017

This paper investigates the mean square performance of the least mean square (LMS) and normalized LMS (NLMS) algorithms with white reference inputs. Their closed-form mean square deviation (MSD) expressions for the transient and steady-state regimes are derived. Additionally, bounds on the step-size which guarantee mean square stability are given. It is found that the step-size bound and transient behavior of the LMS and the steady-state MSD of the NLMS depend on the kurtosis of the input signal. Convergence rates and steady-state MSDs of the two algorithms are then compared, which shows that the normalized variant with a large step-size would offer faster convergence rate than the LMS scheme. However, when small step-sizes are employed, the LMS achieves lower steady-state MSD than the NLMS at the same convergence rate. © 2016 Elsevier B.V.

Kang X.,Southwest Jiaotong University | Cai W.,Southwest Jiaotong University | Zhang S.,Southwest Jiaotong University | Cui S.,Southwest Jiaotong University
Polymer Chemistry | Year: 2017

Dopamine (DA) and its polymer (PDA) have attracted broad interest in recent years. Due to the insolubility of PDA, however, it has been difficult to determine the exact structure and the polymerization mechanism. PDA is usually prepared under alkaline conditions (pH 8.5). In this case, the polymerization process may follow an equilibrium pathway to form indole-like repeating units, which lead to cross-linked structures. However, PDA can be prepared even under acidic conditions (pH 4.0) in the presence of an oxidant, ammonium persulfate (APS), which cannot be interpreted by previous mechanisms. Therefore, there should exist several pathways in parallel on the formation of PDA. Herein, a derivative of DA, 2-(4-methoxy-3-methylphenyl)ethylamine (MOE) that has fewer active sites, is used as a simplified model system to study the polymerization mechanism of DA. Experimental results from UV-Vis spectroscopy, single-molecule force spectroscopy and other measurements indicate that free radical polymerization of MOE occurs under both acidic and alkaline conditions in the presence of a polymerization initiator, APS. According to the mathematical principle of Set Theory and the fact that MOE has fewer active sites than DA, we speculate that free radical polymerization as a possible pathway should exist in parallel along with previously proposed pathways during the formation of PDA. These parallel pathways may be the main reason for the structural complexity of PDA. © 2017 The Royal Society of Chemistry.

Wen P.,Southwest Jiaotong University | Zhang J.,Southwest Jiaotong University
Signal Processing | Year: 2017

A novel variable step-size algorithm is proposed for normalized subband adaptive filter. The proposed algorithm is based on the mixed error cost function. By assuming the time-averaging estimate of the priori and posteriori errors equals the variance of subband noise, the step-size is obtained. Therefore, the proposed algorithm has more effective approach to the optimum solution. The power of noise-free subband priori error is obtained by using the shrinkage denoising method. Using the energy conservation method, the mean-square convergence performance analysis is presented. The analysis result shows this algorithm is stable and effective. The simulation results demonstrate the performance of proposed algorithm distinctly outperforms other conventional variable step-size algorithms in both steady-state error and abrupt tracking performance. © 2017

Ding X.,Southwest Jiaotong University | Liu X.,Southwest Jiaotong University
International Journal of Control, Automation and Systems | Year: 2017

This paper addresses the state-dependent stability problem of switched positive linear systems. Some exponential stability criteria are established on the given partitions of the nonnegative state space. First, a exponential stability of systems without delays is established with the help of a single linear co-positive Lyapunov function. When this does not seem possible, we also prove the stability by using multiple linear co-positive Lyapunov functions. Moreover, we extend this result to the delayed systems in terms of the single and multiple linear co-positive Lyapunov functionals respectively. The proposed results can be applied to the general systems without any special restriction. Some numerical examples are given to illustrate the effectiveness of our results. © 2017 Institute of Control, Robotics and Systems and The Korean Institute of Electrical Engineers and Springer-Verlag Berlin Heidelberg

Li Y.,Southwest Jiaotong University | Fan P.,Southwest Jiaotong University | Leukhin A.,Mari State University | Liu L.,University of Kansas
IEEE Transactions on Vehicular Technology | Year: 2017

The achievable rate of full-duplex (FD) small-cell systems with massive multiple-input multiple-output (MIMO), in which a low-power base station (BS) equipped with large antenna arrays sends/receives data to and from multiple half-duplex (HD) users at the same time on the same frequency, is investigated. The BS uses imperfect channel state information (CSI) obtained from received pilots, nonideal hardware, and a linear transmitter and receiver, i.e., zero-forcing (ZF) or maximum-ratio transmission/maximum-ratio combining (MRT/MRC), to process the signals. The approximate closed-form expressions of the achievable rate for both the ZF and MRT/MRC processing are derived and used to analyze the effect of the number of antennas and the hardware imperfection on the self-interference (SI), which is a bottleneck of the FD systems. To maximize the spectral efficiency (SE) and the energy efficiency (EE) of this system, two nonconvex power-allocation optimization problems are formulated and solved by utilizing the sequential convex approximation technique and the fractional programming technique. Two iterative algorithms are proposed with proved local convergence. Numerical results illustrate that the analytical approximation of achievable rate matches well with the Monte Carlo simulation. It is also shown that the ZF processing has greater ability to suppress SI, compared with MRT/MRC processing. The proposed power-allocation algorithms are shown to increase the SE and EE significantly, compared with the uniform power-allocation scheme when the BS is equipped with moderately large antenna arrays. © 2016 IEEE.

Alexandropoulos G.C.,Huawei | Mathiopoulos P.T.,National and Kapodistrian University of Athens | Fan P.,Southwest Jiaotong University
IEEE Transactions on Vehicular Technology | Year: 2017

The performance of L-branch scan-and-wait combining (SWC) reception systems over arbitrarily correlated and not necessarily identically distributed Nakagami-m fading channels is analyzed and evaluated. First, a fast convergent infinite series representation for the SWC output signal-to-noise ratio (SNR) is presented. This expression is used to obtain analytical expressions in the form of infinite series for the average error probability performance of various modulation schemes for integer values of m as well as the average number of paths estimation and the average waiting time (AWT) of L-branch SWC receivers for arbitrary values of m. The numerically obtained results have shown that the performance expressions converge very fast to their exact analytical values. It was found that the convergence speed depends on the correlation and operating SNR values as well as the Nakagami m-parameter. In addition to the analytical results, complementary computer simulated performance evaluation results have been obtained by means of Monte Carlo error counting techniques. The match between these two sets of results has verified the accuracy of the proposed mathematical analysis. Furthermore, it is revealed that, at the expense of a negligible AWT, the average error probability performance of SWC receivers is always superior to that of switch-and-examine combining receivers and, in certain cases, to that of maximal-ratio combining receivers. © 2016 IEEE.

Qin Y.,Southwest Jiaotong University | Li Y.H.,Southwest Jiaotong University
Mechanical Systems and Signal Processing | Year: 2017

Flapwise vibration characteristics of a rotating laminated composite beam under hygrothermal environment are studied in this paper. The governing equation of the flapwise vibration for the rotating beam under hygrothermal environment is obtained applying D'Alembert's principle, in which the design parameters such as setting angle and pitch angle are considered. A numerical method based on Green's function to handle the vibration characteristics problem of a rotating composite beam is developed. Influences of the hub radius, rotating speed, pitch angle, setting angle, fiber orientation angles, temperature and humidity on natural frequencies of the rotating laminated composite beam are discussed. Results indicate that: (1) the rotating speed, hub radius, setting angle, pitch angle and fiber orientation angle have more prominent effects on natural frequencies than the temperature variation and moisture concentration do; (2) the influences of some parameters such as the hub radius, rotating speed, setting angle and pitch angle on the vibration characteristics are not independent, but coupled with each other. © 2017 Elsevier Ltd

Liang D.,University of Electronic Science and Technology of China | Xu Z.,University of Sichuan | Liu D.,Southwest Jiaotong University
Information Sciences | Year: 2017

Decision-theoretic rough sets (DTRSs) as a classic model of three-way decisions have been widely applied in the area of risk decision-making. When we confront the complicated and uncertain environment, one of challenges is to estimate the loss function of DTRSs. As a new generalization of fuzzy sets, dual hesitant fuzzy sets (DHFSs) can handle uncertain information more flexibly in the process of decision making and give a new measure for the determination of loss functions of DTRSs. To have more interesting results in the context of three-way decisions, we introduce the new hesitant format of DHFSs into DTRSs and explore a new three-way decision model. Firstly, we take into account the loss functions of DTRSs with dual hesitant fuzzy elements (DHFEs) and propose a dual hesitant fuzzy DTRS model. In order to satisfy the preconditions of three-way decisions, we analyze the normalized principle of loss functions under the dual hesitant fuzzy environment. Meanwhile, some properties of the expected losses are carefully investigated. Then, we further design two approaches for deriving three-way decisions with the new DTRS model, i.e., Method 1 and Method 2, which mainly relies on the comparisons among the expected losses. Method 1 is a general method based on the scores and the accuracies of DHFEs. Method 2 is a ranking method of possibility degrees with a stochastic strategy and enriches the comparisons among the expected losses. Finally, the assessment of emergency blood transshipment is used to illustrate and compare these proposed methods. © 2017 Elsevier Inc.

Ding C.,Hong Kong University of Science and Technology | Zhou Z.,Southwest Jiaotong University
Lecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics) | Year: 2017

It has been known for decades that the codewords of a fixed weight in a code may hold a t-design. However, only a small amount of progress on the construction of t-designs from codes has been made so far. It was also proven that the automorphism groups of the extended codes of the narrow-sense primitive BCH codes over finite fields are doubly transitive and these extended codes hold 2-designs. But little is known about the parameters of these 2-designs. The objective of this extended abstract is to present the parameters of some 2-designs held in these extended codes of some classes of narrow-sense primitive BCH codes. © Springer International Publishing AG 2017.

Cui B.,Southwest Jiaotong University
2016 3rd International Conference on Systems and Informatics, ICSAI 2016 | Year: 2016

To the problem of better outstanding the edge for inSfrared and visible images fusion, image local pattern is introduced to the system. Through constructing the gradient similarity kernel function instead of optical proximity kernel function in the traditional bilateral filtering, infrared and visible images fusion algorithm based on gradient bilateral filtering is proposed. The infrared image and the visible image are decomposed into high frequency part low frequency part using the gradient bilateral filtering, then high frequency part of infrared image and visible image are fused by an appropriate fusion rule, and another appropriate fuse rule is used to fuse the low frequency parts of two images. Simulation results show that the fusion algorithm based on gradient bilateral filtering can apply to infrared and visible images fusion, can highlight the image edge, computation time is reasonable, and has better fusion effect. © 2016 IEEE.

Li H.-L.,National Chiao Tung University | Huang Y.-H.,Southwest Jiaotong University | Fang S.-C.,North Carolina State University
INFORMS Journal on Computing | Year: 2017

Polynomial discrete programming problems are commonly faced but hard to solve. Treating the nonconvex cross-product terms is the key. State-of-the-art methods usually convert such a problem into a 0-1 mixedinteger linear programming problem and then adopt the branch-and-bound scheme to find an optimal solution. Much effort has been spent on reducing the required numbers of variables and linear constraints as well as on avoiding unbalanced branch-and-bound trees. This study presents a set of equations that linearize the discrete cross-product terms in an extremely effective manner. It is shown that embedding the proposed "equations for linearizing discrete products" into those state-of-the-art methods in the literature not only significantly reduces the required number of linear constraints from O(h3n3) to O(hn) for a cubic polynomial discrete program with n variables in h possible values but also tighten these methods with much more balanced branch-and-bound trees. Numerical experiments confirm a two-order (102-times) reduction in computational time for some randomly generated cubic polynomial discrete programming problems. There is a Video Overview associated with this article, available as supplemental material. © 2016 INFORMS.

Xiong J.,Southwest Jiaotong University | Lei Y.,Southwest Jiaotong University | Chen H.,Southwest Jiaotong University | Zhang G.,Harbin Institute of Technology
Journal of Materials Processing Technology | Year: 2017

Fabricating geometrical-feature parts using gas metal arc welding (GMAW) additive manufacturing with flat position deposition free from a turn table are proposed through deposition of inclined thin-walled components. During the fabrication process, the torch direction was always maintained perpendicular to the substrate. The definition of inclination angle was presented. Forces of a force model for a pending molten pool were analyzed. Influences of offset distance, wire feed rate, and travel speed on the inclination angle were revealed and discussed. The maximum inclination angle increases along with the travel speed and decreases along with the wire feed rate. A 104-layered cylindrical thin-walled part with geometrical features was fabricated by the proposed approach. Possible sources of fabrication error were presented. © 2016 Elsevier B.V.

Zhang J.-D.,City University of Hong Kong | Chow C.-Y.,City University of Hong Kong | Xu J.,Southwest Jiaotong University
IEEE Transactions on Knowledge and Data Engineering | Year: 2017

In recommender systems, one key task is to predict the personalized rating of a user to a new item and then return the new items having the top predicted ratings to the user. Recommender systems usually apply collaborative filtering techniques (e.g., matrix factorization) over a sparse user-item rating matrix to make rating prediction. However, the collaborative filtering techniques are severely affected by the data sparsity of the underlying user-item rating matrix and often confront the cold-start problems for new items and users. Since the attributes of items and social links between users become increasingly accessible in the Internet, this paper exploits the rich attributes of items and social links of users to alleviate the rating sparsity effect and tackle the cold-start problems. Specifically, we first propose a Kernel-based Attribute-aware M atrix Factorization model called KAMF to integrate the attribute information of items into matrix factorization. KAMF can discover the nonlinear interactions among attributes, users, and items, which mitigate the rating sparsity effect and deal with the cold-start problem for new items by nature. Further, we extend KAMF to address the cold-start problem for new users by utilizing the social links between users. Finally, we conduct a comprehensive performance evaluation for KAMF using two large-scale real-world data sets recently released in Yelp and MovieLens. Experimental results show that KAMF achieves significantly superior performance against other state-of-the-art rating prediction techniques. © 1989-2012 IEEE.

Li Y.-D.,Sichuan University of Science & Engineering | Yang Y.-R.,Southwest Jiaotong University
Nonlinear Dynamics | Year: 2017

The nonlinear governing motion equation of slightly curved pipe with conveying pulsating fluid is set up by Hamilton’s principle. The motion equation is discretized into a set of low dimensional system of nonlinear ordinary differential equations by the Galerkin method. Linear analysis of system is performed upon this set of equations. The effect of amplitude of initial deflection and flow velocity on linear dynamic of system is analyzed. Curves of the resonance responses about (Formula presented.) and (Formula presented.) are performed by means of the pseudo-arclength continuation technique. The global nonlinear dynamic of system is analyzed by establishing the bifurcation diagrams. The dynamical behaviors are identified by the phase diagram and Poincare maps. The periodic motion, chaotic motion and quasi-periodic motion are found in this system. © 2017 Springer Science+Business Media Dordrecht

Tian Y.,Southwest Jiaotong University | Ye X.,University of Jinan
Chemical Record | Year: 2017

Recently, we developed methods to stabilize peptides into various secondary structures, including α-helix, type III turn and β-hairpin via proper thioether based macrocyclization. These conformationally constrained peptidomimetics confer enhanced biophysical properties and provide a valuable avenue towards clinically-relevant therapeutic molecules. In this personal account, thioether-derived macrocyclization methods developed by our group for stabilization of α-helix, type-III β turn and β-hairpin conformations are discussed. © 2017 The Chemical Society of Japan & Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Liang D.,University of Electronic Science and Technology of China | Xu Z.,University of Sichuan | Liu D.,Southwest Jiaotong University
Information Sciences | Year: 2017

Three-way decisions with decision-theoretic rough sets (DTRSs) as a typical risk decision method, are generated by Bayesian decision theory and have three kinds of decision strategies, i.e., the acceptance decision, the deferment (non-commitment) decision and the rejection decision. The construction of three-way decisions under the complex decision-making context creates enormous challenges. The determination of loss function is one of key steps. In this paper, we discuss the decision principles of three-way decision rules based on the variation of loss functions with intuitionistic fuzzy sets (IFSs). More specifically, we introduce the intuitionistic fuzzy point operator (IFPO) into DTRSs and explore three-way decisions. Firstly, we construct a loss function matrix with the point operator and analyze its corresponding properties. IFPO implies one type of variation modes for the loss functions of three-way decisions. With respect to the point operator, we show that the prerequisites among loss functions still hold in each stage. Secondly, given the loss functions, we construct the corresponding three-way decision model and deduce three-way decisions. Finally, with the aid of information entropy theory, we further investigate which stage may be most suitable to make the decision. This study extends the range of applications of three-way decisions to the new intuitionistic fuzzy environment. © 2016 Elsevier Inc.

Chen J.,Sun Yat Sen University | Wei L.F.,Sun Yat Sen University | Wei L.F.,Southwest Jiaotong University
Physical Review A - Atomic, Molecular, and Optical Physics | Year: 2017

NOON states play an important role in quantum information processing and quantum metrology, but the fidelities of these states generated previously are limited, typically by the practically unavoidable decoherence and operational imperfections. Here, we propose an efficient scheme to generate photonic NOON states alternatively using the rapid population passage technique via the shortcut to adiabaticity (STA), rather than the usual Rabi oscillations. Since the deterministic population passages based on the STAs are insensitive to the details of the operations and can be implemented as fast as the Rabi oscillations, the fidelity of the generated NOON state could be satisfactorily high. The feasibility of the proposal is demonstrated specifically with the experimental circuit QED systems by rapidly driving two artificial qutrits. © 2017 American Physical Society.

Gao N.,Southwest Jiaotong University | Zhu Z.-W.,Southwest Jiaotong University
Gaoya Wuli Xuebao/Chinese Journal of High Pressure Physics | Year: 2017

The 5083 aluminum alloy is widely used in engineering, and is inevitably subjected to a variety of different loadings, including strong dynamic loading such as impact and collision. Therefore it is necessary to study its mechanical properties under loading of a wide range of strain rates as well as its constitutive model. With this in view, firstly, an experimental study of the 5083 aluminum alloy was carried out at quasi-static, middle and high strain rates of tension and compression loading and the stress-strain curves of the wide strain rate were obtained. The experimental results show that in the strengthening stage, the tensile stress-strain curves are always lower than the compression stress-strain curves when the experimental condition is kept constant, so the phenomenon is explained by microscopic mechanism. Then, by introducing damage into our study, the effects of damage on the material's mechanical properties were considered under impact tensile loading. Based on the continuum mechanics and experimental results, the damage evolution equation was obtained. Finally, by improving the Johnson-Cook (JC) constitutive model and the existing damage evolution equation, the dynamic constitutive model considering the damage of the 5083 aluminum alloy was established. By comparing the experimental curves with the model curves, it was found that their fitting is good, showing that the proposed model has good applicability. Our research can serve as an effective scientific basis, an analytical model and necessary reference for the engineering application of the 5083 aluminum alloy. © 2017, Editorial Board of Chinese Journal of High Pressure Physics. All right reserved.

Qi X.,Southwest Jiaotong University | Lin W.,Southwest Jiaotong University
Pramana - Journal of Physics | Year: 2017

We investigate the filaments formed by the ultrashort laser pulses with different wavelengths of 400 nm, 586 nm and 800 nm propagating in argon. Numerical results show that, when the input power or the ratio of the input power to the critical power is given, the pulse with 400 nm wavelength has the largest on-axis intensity, as well as the narrowest filament and the most stable beam radius. These results indicate that the pulse with shorter wavelength is more suitable for the long-range propagation in argon. © Indian Academy of Sciences.

Zhang L.,Southwest Jiaotong University | Gao H.,Southwest Jiaotong University
Proceedings of 2016 Prognostics and System Health Management Conference, PHM-Chengdu 2016 | Year: 2016

As ball screw has complex structure and long range of distribution, single signal collected by one sensor is difficult to express its condition fully and accurately. Multi-sensor data fusion usually has a better effect compared with single signal. Multi-sensor data fusion based on neural network(BP) is a commonly used multi-sensor data fusion method, but its application is limited by local optimum problem. Aiming at this problem, a multi-sensor data fusion method based on deep learning for ball screw is proposed in this paper. Deep learning, which consists of unsupervised learning and supervised learning, is the development and evolution of traditional neural network. It can effectively alleviate the optimization difficulty. Parallel superposition on frequency spectra of signals is directly done in the proposed deep learning-based multi-sensor data fusion method, and deep belief networks(DBN) are established by using fused data to adaptively mine available fault characteristics and automatically identify the degradation condition of ball screw. Test is designed to collect vibration signals of ball screw in 7 different degradation conditions by using 5 acceleration sensors installed on different places. The proposed fusion method is applied in identifying the degradation degree of ball screw in the test to demonstrate its efficacy. Finally, the multi-sensor data fusion based on neural network is also applied in degradation degree monitoring. The monitoring accuracy of deep learning-based multi-sensor data fusion is higher compared with that of neural network-based multi-sensor data fusion, which means the proposed method has more superiority. © 2016 IEEE.

Zhong F.,Southwest Jiaotong University | Zhong F.,Yibin University | Zhang J.,Southwest Jiaotong University
Neurocomputing | Year: 2013

This paper presents a novel approach based on enhanced local directional patterns (ELDP) to face recognition, which adopts local edge gradient information to represent face images. Specially, each pixel of every facial image sub-block gains eight edge response values by convolving the local 3×3 neighborhood with eight Kirsch masks, respectively. ELDP just utilizes the directions of the most prominent edge response value and the second most prominent one. Then, these two directions are encoded into a double-digit octal number to produce the ELDP codes. The ELDP dominant patterns (ELDPd) are generated by statistical analysis according to the occurrence rates of the ELDP codes in a mass of facial images. Finally, the face descriptor is represented by using the global concatenated histogram based on ELDP or ELDPd extracted from the face image which is divided into several sub-regions. The performances of several single face descriptors not integrated schemes are evaluated in face recognition under different challenges via several experiments. The experimental results demonstrate that the proposed method is more robust to non-monotonic illumination changes and slight noise without any filter. © 2013 Elsevier B.V.

Zhong F.,Southwest Jiaotong University | Zhong F.,Yibin University | Zhang J.,Southwest Jiaotong University
IEEE Transactions on Image Processing | Year: 2013

Linear discriminant analysis (LDA) is a well-known dimensionality reduction technique, which is widely used for many purposes. However, conventional LDA is sensitive to outliers because its objective function is based on the distance criterion using L2-norm. This paper proposes a simple but effective robust LDA version based on L1-norm maximization, which learns a set of local optimal projection vectors by maximizing the ratio of the L1-norm-based between-class dispersion and the L1-norm-based within-class dispersion. The proposed method is theoretically proved to be feasible and robust to outliers while overcoming the singular problem of the within-class scatter matrix for conventional LDA. Experiments on artificial datasets, standard classification datasets and three popular image databases demonstrate the efficacy of the proposed method. © 1992-2012 IEEE.

Zhou X.J.,Southwest Jiaotong University | Yang C.Y.,The 1st Design Institute of Civil Engineering and Architecture
Applied Mechanics and Materials | Year: 2013

Structural design and construction process for a subway station consists of two tunnels with large transection are discussed according to its function and geological conditions of rock mass in this paper. A composite lining is designed to support surrounding rock, and partial bench cut method, side drift method are utilized to build the special subway transfer station in rock mass. The practice of the designed scenario proves to be a great success and attains the safe construction of the station by tunneling method. © (2013) Trans Tech Publications, Switzerland.

Wang C.,Southwest Jiaotong University | Sun D.,National University of Singapore | Toh K.-C.,National University of Singapore
SIAM Journal on Optimization | Year: 2010

We propose a Newton-CG primal proximal point algorithm (PPA) for solving large scale log-determinant optimization problems. Our algorithm employs the essential ideas of PPA, the Newton method, and the preconditioned CG solver. When applying the Newton method to solve the inner subproblem, we find that the log-determinant term plays the role of a smoothing term as in the traditional smoothing Newton technique. Focusing on the problem of maximum likelihood sparse estimation of a Gaussian graphical model, we demonstrate that our algorithm performs favorably compared to existing state-of-the-art algorithms and is much preferred when a high quality solution is required for problems with many equality constraints. © 2010 Society for Industrial and Applied Mathematics.

Zhou Y.,Southwest Jiaotong University
Lecture Notes in Electrical Engineering | Year: 2012

In this paper, new families of zero correlation zone (ZCZ) sequences based on interleaving technique and perfect sequences are constructed. The proposed sequences have the property that, in a specified zone, the out-of-phase autocorrelation and cross-correlation values are all equal to zero. Due to this property, such sequences are suitable for quasi-synchronous code-division multiple access (QS-CDMA) systems. It is shown that that all the proposed ZCZ sequences are pairwise cyclically distinct. Furthermore, the condition under which the constructed ZCZ sequences are optimal is derived. abstract environment. © Springer-Verlag Berlin Heidelberg 2012.

Zhang G.,Southwest Jiaotong University | Gheorghe M.,University of Sheffield | Pan L.,Huazhong University of Science and Technology | Perez-Jimenez M.J.,University of Seville
Information Sciences | Year: 2014

Evolutionary membrane computing is an important research direction of membrane computing that aims to explore the complex interactions between membrane computing and evolutionary computation. These disciplines are receiving increasing attention. In this paper, an overview of the evolutionary membrane computing state-of-the-art and new results on two established topics in well defined scopes (membrane-inspired evolutionary algorithms and automated design of membrane computing models) are presented. We survey their theoretical developments and applications, sketch the differences between them, and compare the advantages and limitations. © 2014 Elsevier Inc. All rights reserved.

Zhang L.,Southwest Jiaotong University | Zhang J.,Southwest Jiaotong University | Zhang J.,National United Engineering Laboratory of Integrated and Intelligent Transportation | Tang X.,Southwest Jiaotong University
IEEE Transactions on Wireless Communications | Year: 2013

With the development of radio frequency identification (RFID) technology, RFID systems have been used in various applications. But the tag collision problem greatly affects the performance of many RFID systems, especially in large scale tag identification environments. In this paper, we propose two new efficient tag anti-collision protocols, i.e., the assigned tree slotted Aloha (ATSA) protocol and the improved ATSA (ImATSA) protocol based upon Manchester encoding. The key technology is to apply the prefix matching idea to the dynamic frame slotted Aloha identification model by assigning a unique ID prefix to each frame and slot. Both theoretical and simulation results indicate that ImATSA can achieve an average system efficiency of around 58%. © 2013 IEEE.

Luo W.,Guangxi University for Nationalities | Luo W.,Southwest Jiaotong University | Fang X.,Guangxi University for Nationalities | Cheng M.,Guangxi University for Nationalities | Zhao Y.,Algorithm
IEEE Transactions on Vehicular Technology | Year: 2013

The capacity of a multiple-input-multiple-output (MIMO) channel with $N$ transmit and receive antennas for high-speed railways (HSRs) is analyzed based on the 3-D modeling of the line of sight (LOS). The MIMO system utilizes a uniform linear antenna array. Instead of increasing the number of antennas or simply changing the parameters of the antenna array, such as separation and geometry, the capacity gain can be obtained by adjusting the weights of multiantenna array groups, because there are few scatterers in strong LOS environments. On the other hand, it is hard to obtain the array gain of MIMO beamforming for HSRs because of drastic changes in the receiving angle when the train travels across E-UTRAN Node B. Without changing the antenna design of Long-Term Evolution systems, this paper proposes a multiple-group multiple-antenna (MGMA) scheme that makes the columns of such a MIMO channel orthogonal by adjusting the weights among MGMA arrays, and the stable capacity gain can be obtained. The value of weights depends on the practical network topologies of the railway wireless communication system. However, the reasonable scope of group number $N$ is less than 6. In selecting $N$, one important consideration is the tradeoff between practical benefit and cost of implementation. © 1967-2012 IEEE.

Kang G.,Southwest Jiaotong University | Bruhns O.T.,Ruhr University Bochum | Sai K.,University of Sfax
Computational Materials Science | Year: 2011

Based on a cyclic crystal visco-plastic model developed in previous work for face-centered cubic (FCC) single crystals, a new polycrystalline visco-plastic model is constructed to describe the ratchetting of 316L stainless steel. In the constructed model, a combined nonlinear kinematic hardening rule is employed to describe the resolved shear back stress of each active slip system, and a simplified version of Bassani-Wu latent hardening model is used to capture the interaction of dislocation slip. An explicit scale-transition rule is adopted to obtain the polycrystalline behavior of metal materials. Comparing the simulated results with the experimental ones shows that the developed cyclic polycrystalline visco-plastic model provides reasonable description for the uniaxial ratchetting of 316L stainless steel. The dependence of ratchetting deformation on crystallographic orientation in intra-granular scale can be also reflected correctly by the developed model, and the applicability of the model to multiaxial ratchetting is also discussed. © 2010 Elsevier B.V. All rights reserved.

Wen K.,Guangdong University of Technology | Wen K.,Southwest Jiaotong University | Yan L.,Southwest Jiaotong University | Pan W.,Southwest Jiaotong University | And 4 more authors.
Journal of Lightwave Technology | Year: 2014

A plasmonic bus waveguide with a side-coupled T-shaped (TS) or a reverse T-shaped (RTS) resonator consisting of a parallel and a perpendicular cavities is proposed. The compact configuration could serve as a wavelength demultiplexing device as a forbidden band is achieved based on the symmetric distribution of resonators. By shifting one cavity away from the center of the resonator, the system exhibits electromagnetically induced transparency (EIT) like transmission at the wavelength of the former forbidden band. The electromagnetic responses of the structure could be handled with certain flexibility by changing the asymmetric behavior of the TS or RTS resonator. Similar characteristics for two proposed structures could be obtained except for the center wavelength that is determined by the two cavities in the RTS resonator or by the cavity parallel to the bus waveguide in the TS resonator. © 1983-2012 IEEE.

Wang K.,China Institute of Technology | Wang K.,Signal Sciences | Zhao H.,South University of Science and Technology of China | Wang H.,Southwest Jiaotong University
IEEE Transactions on Information Forensics and Security | Year: 2014

This paper presents a method for detection of motion vector-based video steganography. First, the modification on the least significant bit of the motion vector is modeled. The influence of the embedding operation on the sum of absolute difference (SAD) is illustrated, which allows us to focus on the difference between the actual SAD and the locally optimal SAD after the adding-or-subtracting-one operation on the motion value. Finally, based on the fact that most motion vectors are locally optimal for most video codecs, two feature sets are extracted and used for classification. Experiments are carried out on videos corrupted by various steganography methods and encoded by various motion estimation methods, in various bit rates, and in various video codecs. Performance results demonstrate that our scheme outperforms previous works in general, and is more favorable for real-world applications. © 2014 IEEE.

Tong X.,Southwest Jiaotong University | Wang X.,Southwest Jiaotong University | Wang R.,Southwest Jiaotong University | Huang F.,Southwest Jiaotong University | And 3 more authors.
IEEE Transactions on Smart Grid | Year: 2013

Conventional protection relays, which use local signals to locate faults, are a poor fit to modern power grids when compared to communication-based alternatives. This article presents a novel Wide-Area Backup Protection (WABP) algorithm that uses information shared across wide-area communication networks. The WABP algorithm fuses and integrates information in a regional decentralized peer-to-peer negotiation architecture for enhanced effectiveness. Line decision-making agents (LDAs), focused on line-fault detection, collect distance and directional protection information on both sides of a line. If LDAs cannot detect a fault locally, wide-area information that includes directional protection and line-fault states from neighboring lines is collected to locate the fault. The LDA considers the possible presence of relay misoperations, protection failures, and/or communication failures. Regional decision-making agents (RDAs) that reside in a regional decision-making device (RDD) in the monitoring layer of a substation can negotiate in a peer-to-peer manner without a control center. The RDA serves as the manager, coordinator, and message transponder for the LDAs. The design of the WABP is described including its architecture, workflow, and its agents' functions. Simulation scenarios illustrate the correctness of the WABP multi-agent system and the higher fault-tolerance of its response to misoperations, protection failures, and communication failures. © 2010-2012 IEEE.

Lin C.,Southwest Jiaotong University | Lin C.,National University of Singapore | Qing A.,National University of Singapore | Feng Q.,Southwest Jiaotong University
Journal of Global Optimization | Year: 2011

A new differential mutation base strategy for differential evolution (DE), namely best of random, is proposed. The best individual among several randomly chosen individuals is chosen as the differential mutation base while the other worse individuals are donors for vector differences. Hence both good diversity and fast evolution speed can be obtained in DE using the new differential mutation base. A comprehensive comparative study is carried out over a set of benchmark functions. Numerical results show that a better balance of reliability and efficiency can be obtained in differential evolution implementing the new generator of differential mutation base, especially in functions with high dimension. © 2010 Springer Science+Business Media, LLC.

Zhang G.,Southwest Jiaotong University | Rong H.,Southwest Jiaotong University | Neri F.,De Montfort University | Perez-Jimenez M.J.,University of Seville
International Journal of Neural Systems | Year: 2014

Membrane systems (also called P systems) refer to the computing models abstracted from the structure and the functioning of the living cell as well as from the cooperation of cells in tissues, organs, and other populations of cells. Spiking neural P systems (SNPS) are a class of distributed and parallel computing models that incorporate the idea of spiking neurons into P systems. To attain the solution of optimization problems, P systems are used to properly organize evolutionary operators of heuristic approaches, which are named as membrane-inspired evolutionary algorithms (MIEAs). This paper proposes a novel way to design a P system for directly obtaining the approximate solutions of combinatorial optimization problems without the aid of evolutionary operators like in the case of MIEAs. To this aim, an extended spiking neural P system (ESNPS) has been proposed by introducing the probabilistic selection of evolution rules and multi-neurons output and a family of ESNPS, called optimization spiking neural P system (OSNPS), are further designed through introducing a guider to adaptively adjust rule probabilities to approximately solve combinatorial optimization problems. Extensive experiments on knapsack problems have been reported to experimentally prove the viability and effectiveness of the proposed neural system. © World Scientific Publishing Company.

Xu X.,Xihua University | Zhang J.,Southwest Jiaotong University | Shi J.,Zhejiang Normal University
Neurocomputing | Year: 2014

This paper investigates the problem of the dynamic behaviors of a class of complex-valued neural networks with mixed time delays. Some sufficient conditions for assuring the existence, uniqueness and exponential stability of the equilibrium point of the system are derived using the vector Lyapunov function method, homeomorphism mapping lemma and the matrix theory. The obtained results not only are convenient to check, but also generalize the previously published corresponding results. A numerical example is used to show the effectiveness of the obtained results. © 2013 Elsevier B.V.

Lin C.,Southwest Jiaotong University | Qing A.,National University of Singapore | Feng Q.,Southwest Jiaotong University
IEEE Transactions on Antennas and Propagation | Year: 2010

Synthesis of unequally spaced linear antenna arrays is considered in this paper. A recently developed new differential evolution algorithm is applied to solve the problem. Both position-only and position-phase synthesis have been studied. Effect of angle resolution has also been investigated. Synthesis results show that our algorithm is able to obtain better synthesis result reliably and efficiently. © 2006 IEEE.

Qian Z.S.,University of California at Davis | Xiao F.E.,Southwest Jiaotong University | Zhang H.M.,University of California at Davis
Transportation Research Part A: Policy and Practice | Year: 2011

In this paper, we study the economics of parking provision for the morning commute, where all the parking lots are owned and operated by private operators. The parking capacity allocations, parking fees and access times are considered in a parking market. First we solve the parking market equilibrium without regulatory intervention, revealing four types of competitive equilibrium. Only one of the four types of equilibrium, however, is found to be stable and realistic, and under it each parking area is preferred by the commuters during certain time periods. Compared to the case without parking choice, provision of parking through a competitive market is able to reduce commuters' travel cost and queuing delay, but it does not necessarily lead to the most desirable market outcome that minimizes social cost or commuter cost. This issue can be addressed through market regulations, such as price-ceiling, capacity-floor or capacity-ceiling, and a quantity tax/subsidy regulation. It is found that both price-ceiling and quantity tax/subsidy regulations can efficiently reduce both the system cost and commuter cost under certain conditions, and help ensure the stability of the parking market. Numerical examples are also provided to illustrate these findings and furthermore, how a price ceiling or a quantity tax/subsidy should be set in a parking market under realistic model parameters. © 2011 Elsevier Ltd.

Hu Y.,Southwest Jiaotong University | Hu Y.,Bar - Ilan University | Hu Y.,Beijing Normal University | Ksherim B.,Bar - Ilan University | And 2 more authors.
Physical Review E - Statistical, Nonlinear, and Soft Matter Physics | Year: 2011

Robustness of two coupled networks systems has been studied separately only for dependency coupling and only for connectivity coupling. Here we study, using a percolation approach, a more realistic coupled networks system where both interdependent and interconnected links exist. We find rich and unusual phase-transition phenomena including hybrid transition of mixed first and second order, i.e., discontinuities like in a first-order transition of the giant component followed by a continuous decrease to zero like in a second-order transition. Moreover, we find unusual discontinuous changes from second-order to first-order transition as a function of the dependency coupling between the two networks. © 2011 American Physical Society.

Cui W.,Southwest Jiaotong University | Cui W.,Shanghai JiaoTong University | Li X.,Southwest Jiaotong University | Xie C.,Southwest Jiaotong University | And 3 more authors.
Biomaterials | Year: 2010

Controlled nucleation and growth of hydroxyapatite (HA) crystals on electrospun fibers should play important roles in fabrication of composite scaffolds for bone tissue engineering, but no attempt has been made to clarify the effects of chemical group densities and the cooperation of two and more groups on the biomineralization process. The aim of the current study was to investigate into HA nucleation and growth on electrospun poly(dl-lactide) fibers functionalized with carboxyl, hydroxyl and amino groups and their combinations. Electrospun fibers with higher densities of carboxyl groups, combination of hydroxyl and carboxyl groups with the ratio of 3/7, and combination of amino, hydroxyl and carboxyl groups with the ratio of 2/3/5 were favorable for HA nucleation and growth, resulting in higher content and lower crystal size of formed HA. Carboxyl groups were initially combined with calcium ions through electrostatic attraction, and the introduction of hydroxyl groups could modulate the distance between carboxyl groups. The introduction of amino groups may lead to the inner ionic bonding with carboxyl groups, but can accelerate phosphate ions to form HA through a chelate ring with the calcium ion and carbonyl oxygen. The biological evaluation indicated that the mineralized scaffolds acted as an excellent cell support to maintain desirable cell-substrate interactions, to provide favorable conditions for cell proliferation and to stimulate the osteogenic differentiation. © 2010 Elsevier Ltd.

Wang Y.,Shanghai JiaoTong University | Wei Yu.,Southwest Jiaotong University | Wu C.,Shanghai JiaoTong University
Physica A: Statistical Mechanics and its Applications | Year: 2011

In this paper, we study the auto-correlations and cross-correlations of West Texas Intermediate (WTI) crude oil spot and futures return series employing detrended fluctuation analysis (DFA) and detrended cross-correlation analysis (DCCA). Scaling analysis shows that, for time scales smaller than a month, the auto-correlations and cross-correlations are persistent. For time scales larger than a month but smaller than a year, the correlations are anti-persistent, while, for time scales larger than a year, the series are neither auto-correlated nor cross-correlated, indicating the efficient operation of the crude oil markets. Moreover, for small time scales, the degree of short-term cross-correlations is higher than that of auto-correlations. Using the multifractal extension of DFA and DCCA, we find that, for small time scales, the correlations are strongly multifractal, while, for large time scales, the correlations are nearly monofractal. Analyzing the multifractality of shuffled and surrogated series, we find that both long-range correlations and fat-tail distributions make important contributions to the multifractality. Our results have important implications for market efficiency and asset pricing models. © 2010 Elsevier B.V. All rights reserved.

Ren F.,Hong Kong University of Science and Technology | Ren F.,University of Illinois at Urbana - Champaign | Lu X.,Southwest Jiaotong University | Leng Y.,Hong Kong University of Science and Technology
Journal of the Mechanical Behavior of Biomedical Materials | Year: 2013

Ab initio quantum mechanical (QM) calculations were employed to study the crystal structure and elastic properties of carbonated apatite (CAp). Two locations for the carbonate ion in the apatite lattice were considered: carbonate substituting for OH- ion (type-A), and for PO4 3- ion (type-B) with possible charge compensation mechanisms. A combined type-AB substitution (two carbonate ions replacing one phosphate group and one hydroxyl group, respectively) was also investigated. The results show that the most energetically stable substitution is type-AB, followed by type-A and then type-B. The most stable configuration of type-A has its carbonate triangular plane almost parallel to c-axis at z=0.46. The lowest energy configuration of type-B is that with a sodium ion substituting for a calcium ion for charge balance and the carbonate lying on the b/c-plane of apatite. Lattice parameter changes after carbonate substitution in hydroxyapatite (HA) agree with reported experimental results qualitatively: for type-A, lattice parameter a increases but c decreases; and for type-B, lattice parameter a decreases but c increases. Using the calculated CAp stable structures, we also calculated the elastic properties of CAp and compared them with those of HA and biological apatites. © 2013 Elsevier Ltd.

Wang Y.,Shanghai JiaoTong University | Wei Y.,Southwest Jiaotong University | Wu C.,Shanghai JiaoTong University
Physica A: Statistical Mechanics and its Applications | Year: 2010

In this paper, we investigate the long-range auto-correlated behavior of WTI crude oil volatility series employing multifractal detrended fluctuation analysis. Our findings show that the for small time scales, the auto-correlations of volatilities were multifractal while for large time scales, the auto-correlations were nearly monofractal. Based on multiscale analysis, we also investigate the dynamics of auto-correlations for different intervals of time scales and find that several shocks could make significant effects on the auto-correlated behaviors for small time scales. Analyzing the dynamics of multifractality degrees of auto-correlations for small time scales, we find that the stronger auto-correlations were always related to the lower degrees of multifractality. At last, we have discussions on the determination factors of price behavior, the predictive implications of scaling behavior in volatilities for oil markets and the reasons why long-range auto-correlations of volatility were always strong for both small time scales and large time scales. Our results are very important theoretically and practically. © 2010 Elsevier B.V. All rights reserved.

Wang Y.,Shanghai JiaoTong University | Wei Y.,Southwest Jiaotong University | Wu C.,Shanghai JiaoTong University
Physica A: Statistical Mechanics and its Applications | Year: 2010

In this paper, we investigate the cross-correlations between Chinese A-share and B-share markets. Qualitatively, we find that the return series of Chinese A-share and B-share markets were overall significantly cross-correlated based on the analysis of a statistic. Quantitatively, employing the detrended cross-correlation analysis, we find that the cross-correlations were strongly multifractal in the short-term and weakly multifractal in the long-term. Moreover, the cross-correlations of small fluctuations were persistent and those of large fluctuations were anti-persistent in the short-term while cross-correlations of all kinds of fluctuations were persistent in the long-term. Using the method of rolling windows, we find that the cross-correlations were weaker and weaker over time, especially after the price-limited reform. We attribute the fact to the improvement of market efficiency. On the volatility series, our results show that the cross-correlations were much stronger than those between return series. Results from rolling windows show that the short-term cross-correlations between volatility series are still high now. We also provide some relevant discussions later. © 2010 Elsevier B.V. All rights reserved.

Ma G.T.,TU Darmstadt | Ma G.T.,Southwest Jiaotong University | Rauh H.,TU Darmstadt
Superconductor Science and Technology | Year: 2013

Numerical simulations of thermo-electromagnetic properties of a thin type-II superconductor strip surrounded by open cavity soft-magnetic shields and exposed to an oscillating transverse magnetic field are performed by resorting to the quasistatic approximation of a vector potential approach in conjunction with the classical description of conduction of heat. The underlying definition of the superconducting constituent makes use of an extended 'smoothed' Bean model of the critical state, which includes the field and temperature dependence of the induced supercurrent as well. The delineation of the magnetic shields exploits the reversible-paramagnet approximation in the Langevin form, as appropriate for magnetizations with narrow Z-type loops, and considers induced eddy currents too. The coolant is envisaged as acting like a bath that instantly takes away surplus heat. Based on the Jacobian-free Newton-Krylov approach and the backward Euler scheme, the numerical analysis at hand is tailored to the problem of a high width/thickness aspect ratio of the superconductor strip. Assigning representative materials characteristics and conditions of the applied magnetic field, the main findings for a practically relevant magnet configuration include: (i) an overall rise of the maximum temperature of the superconductor strip tending to saturation in a superconducting thermo-electromagnetic steady state above the operating temperature, magnetic shielding lending increased stability and smoothing the temperature profile along the width of the superconductor strip; (ii) a washing out of the profile of the magnetic induction and a lowering of its strength, a relaxation of the profile of the supercurrent density and an increase of its strength, a tightening of the power loss density and a reduction of its strength, all inside the superconductor strip. The hysteretic ac loss suffered by the superconductor strip is seen to be cut back or, at most, to converge on that of an unshielded strip, thermo-electromagnetic coupling merely playing an insignificant part thereby. © 2013 IOP Publishing Ltd.

Pei Y.-L.,Beihang University | He J.,Xi'an University of Science and Technology | Li J.-F.,Tsinghua University | Fuli,Tsinghua University | And 7 more authors.
NPG Asia Materials | Year: 2013

We report on the high thermoelectric performance of p-type polycrystalline BiCuSeO, a layered oxyselenide composed of alternating conductive (Cu 2Se2)2- and insulating (Bi2O 2)2+ layers. The electrical transport properties of BiCuSeO materials can be significantly improved by substituting Bi3+ with Ca2+ . The resulting materials exhibit a large positive Seebeck coefficient of ∼+330μVK-1 at 300 K, which may be due to the 'natural superlattice' layered structure and the moderate effective mass suggested by both electronic density of states and carrier concentration calculations. After doping with Ca, enhanced electrical conductivity coupled with a moderate Seebeck coefficient leads to a power factor of ∼4.74μWc-1K-2 at 923 K. Moreover, BiCuSeO shows very low thermal conductivity in the temperature range of 300 (∼0.9 Wm -1 K-1 )to923K(∼0.45 Wm-1K-1 ). Such low thermal conductivity values are most likely a result of the weak chemical bonds (Young's modulus, E∼76.5 GPa) and the strong anharmonicity of the bonding arrangement (Gruneisen parameter, γ∼1.5). In addition to increasing the power factor, Ca doping reduces the thermal conductivity of the lattice, as confirmed by both experimental results and Callaway model calculations. The combination of optimized power factor and intrinsically low thermal conductivity results in a high ZT of ∼0.9 at 923K for Bi 0.925Ca0.075CuSeO. © 2013 Nature Publishing Group .

Webb R.C.,University of Illinois at Urbana - Champaign | Bonifas A.P.,University of Illinois at Urbana - Champaign | Behnaz A.,U.S. National Institutes of Health | Zhang Y.,Tsinghua University | And 15 more authors.
Nature Materials | Year: 2013

Precision thermometry of the skin can, together with other measurements, provide clinically relevant information about cardiovascular health, cognitive state, malignancy and many other important aspects of human physiology. Here, we introduce an ultrathin, compliant skin-like sensor/actuator technology that can pliably laminate onto the epidermis to provide continuous, accurate thermal characterizations that are unavailable with other methods. Examples include non-invasive spatial mapping of skin temperature with millikelvin precision, and simultaneous quantitative assessment of tissue thermal conductivity. Such devices can also be implemented in ways that reveal the time-dynamic influence of blood flow and perfusion on these properties. Experimental and theoretical studies establish the underlying principles of operation, and define engineering guidelines for device design. Evaluation of subtle variations in skin temperature associated with mental activity, physical stimulation and vasoconstriction/dilation along with accurate determination of skin hydration through measurements of thermal conductivity represent some important operational examples. © 2013 Macmillan Publishers Limited. All rights reserved.

Guan L.,Southwest Jiaotong University | Guan L.,Chongqing University of Posts and Telecommunications | Guan L.,Chongqing Jiaotong University | Wang G.,Southwest Jiaotong University | Wang G.,Chongqing University of Posts and Telecommunications
Information Sciences | Year: 2012

The classical rough set theory, based on the conventional indiscernibility relation, is not much useful for analyzing incomplete information. Some successful generalized rough set models based on different non-equivalence relations have been proposed. Nowadays the generalized definitions of approximations have become one of the important research issues of the generalized rough set models. Although some different definitions of approximations have been presented, the relationships among them have not been analyzed adequately. In this paper, we investigate the relationships among 12 different basic definitions of approximations and suggest the suitable generalized definitions of approximations for each class of generalized indiscernibility relations. We also review eight classes of generalized indiscernibility relations and 12 different basic definitions of approximations as our foundations for discussion. Three examples are given to illustrate the relationships among the different generalized definitions of approximations. © 2011 Elsevier Inc. All rights reserved.

Gong X.,Southwest Jiaotong University | Li X.-X.,University of Sichuan | Feng L.,Sichuan Normal University | Xia R.,Chongqing University of Posts and Telecommunications
International Journal of Machine Learning and Cybernetics | Year: 2012

When applying Chan-Vese (C-V) model to segment a face from an image, the result is always influenced by the initial position, especially in a real scenarios with clutter background. An improved skin tone detection model is proposed based on the Gaussian function, which could generate an accurate initial contour for C-V model. As the single Gaussian model (SGM) only uses the prior information to determine the likelihood of a pixel, it lacks adaptability for an image with lighting and poses variances. A more adaptive SGM (ASGM) is proposed in this paper that, by updating the model parameters according to the input image, could provide a more stable approximation of face region. And then, we apply the estimated initial contour to C-V model for precise face segmentation. Tests conducted on a public face dataset (220 images with pose and illumination changes) have shown that the accuracy of skin region detected by ASGM is at a ratio higher than 99%, which lays a good foundation for further segmentation by the C-V model. Extensive experiments have validated effectiveness and efficiency of our system in face segmentation. © 2011 Springer-Verlag.

Wang Y.,Shanghai JiaoTong University | Wei Yu.,Southwest Jiaotong University | Wu C.,Shanghai JiaoTong University
Physica A: Statistical Mechanics and its Applications | Year: 2011

In this paper, we investigate the efficiency and multifractality of a gold market based on multifractal detrended fluctuation analysis. Our evidence shows that the gold return series are multifractal both for time scales smaller than a month and for time scales larger than a month. For time scales smaller than a month, the main contribution of multifractality is fat-tail distribution. For time scales larger than a month, both long-range correlations and fat-tail distribution play important roles in the contribution of multifractality. Using the method of rolling windows, we find that the gold market became more and more efficient over time, especially after 2001. The abnormal points of scaling exponents can also be related to some occasional events. By defining a new inefficiency measure related to the multifractality, we find that the gold market is more efficient during the upward periods than during the downward periods. © 2010 Elsevier B.V. All rights reserved.

Wei Y.,Southwest Jiaotong University | Wang Y.,Shanghai JiaoTong University | Huang D.,Southwest Jiaotong University
Physica A: Statistical Mechanics and its Applications | Year: 2011

In this paper, we propose a new hedging model combining the newly introduced multifractal volatility (MFV) model and the dynamic copula functions. Using high-frequency intraday quotes of the spot Shanghai Stock Exchange Composite Index (SSEC), spot China Securities Index 300 (CSI 300), and CSI 300 index futures, we compare the direct and cross hedging effectiveness of the copulaMFV model with several popular copulaGARCH models. The main empirical results show that the proposed copulaMFV model obtains better hedging effectiveness than the copulaGARCH-type models in general. Furthermore, the hedge operating strategy based MFV hedging model involves fewer transaction costs than those based on the GARCH-type models. The finding of this paper indicates that multifractal analysis may offer a new way of quantitative hedging model design using financial futures. © 2011 Elsevier B.V. All rights reserved.

Luo M.-X.,Southwest Jiaotong University | Luo M.-X.,Beijing University of Posts and Telecommunications | Ma S.-Y.,Henan University | Chen X.-B.,Beijing University of Posts and Telecommunications | Wang X.,Dublin City University
Physical Review A - Atomic, Molecular, and Optical Physics | Year: 2015

Quantum state joining has been recently experimentally demonstrated [C. Vitelli, Nat. Photon. 7, 521 (2013)1749-488510.1038/nphoton.2013.107] which can transfer two input photonic qubits into a photonic ququart. Here, we revisit these processes from a hybrid point of view. By exploring the giant optical circular birefringence induced by quantum-dot spins in one-sided optical microcavities, we introduce some deterministic joining schemes including two quantum-dot spin joining, hybrid photon and quantum-dot spin joining, and two-photon joining. The input quantum information is represented by one photon with polarization and spatial mode degrees of freedom (DOFs). These schemes are also adapted to the inverse processes called quantum state splitting because all the joining procedures are unitary and do not require projection and feed-forward steps. The fused photon is convenient for realizing elementary logic gates such as the controlled-not (cnot) gate, swap gate, and Toffoli gate. These hybrid fusion and splitting schemes provide flexible synthesis of the quantum-dot spin and photon in quantum applications. The transmission superiority of photons and storage superiority of the quantum-dot spin may be combined for quantum network communication or quantum computations. © 2015 American Physical Society.

Qureshi S.S.,Beijing University of Posts and Telecommunications | Ahmad T.,Beijing University of Posts and Telecommunications | Rafique K.,Beijing University of Posts and Telecommunications | Shuja-Ul-Islam,Southwest Jiaotong University
CCIS2011 - Proceedings: 2011 IEEE International Conference on Cloud Computing and Intelligence Systems | Year: 2011

In recent years cloud computing has gained a momentum and is transforming the internet computing infrastructure. Also the mobile applications and mobile devices are developing rapidly. Cloud computing is anticipated to bring an innovation in mobile computing, where the mobile devices can use clouds for data processing, storage and other intensive operations. Already there are some mobile cloud applications for example Google's Map, Gmail for iPhone and Cisco's WebEx on iPad, however these applications are using the Software as a Service model. In this paper we introduce state-of-the-art Mobile Cloud Computing and its implementation methods. We also investigate some critical issues to be solved and point-out further future research directions. © 2011 IEEE.

Wei Y.,Southwest Jiaotong University | Wang Y.,Shanghai JiaoTong University | Huang D.,Southwest Jiaotong University
Energy Economics | Year: 2010

This paper extends the work of Kang et al. (2009). We use a greater number of linear and nonlinear generalized autoregressive conditional heteroskedasticity (GARCH) class models to capture the volatility features of two crude oil markets - Brent and West Texas Intermediate (WTI). The one-, five- and twenty-day out-of-sample volatility forecasts of the GARCH-class models are evaluated using the superior predictive ability test and with more loss functions. Unlike Kang et al. (2009), we find that no model can outperform all of the other models for either the Brent or the WTI market across different loss functions. However, in general, the nonlinear GARCH-class models, which are capable of capturing long-memory and/or asymmetric volatility, exhibit greater forecasting accuracy than the linear ones, especially in volatility forecasting over longer time horizons, such as five or twenty days. © 2010 Elsevier B.V.

Wang G.,Southwest Jiaotong University | Wang G.,Chongqing University of Posts and Telecommunications | Wang G.,Chongqing University of Technology | Xu C.,Southwest Jiaotong University | And 2 more authors.
Information Sciences | Year: 2014

Cloud model is a cognitive model which can realize the bidirectional cognitive transformation between qualitative concept and quantitative data based on probability statistics and fuzzy set theory. It uses the forward cloud transformation (FCT) and the backward cloud transformation (BCT) to implement the cognitive transformations between the intension and extension of a concept. As one of the most important cloud models, the normal cloud models, especially the 2nd-order normal cloud model based on normal distribution and Gaussian membership function has been extensively researched and successfully applied to many fields. In this paper, a 2nd-order generic normal cloud model, which establishes a relationship between normal cloud and normal distribution, is proposed, and the 2nd-order generic forward normal cloud transformation algorithm (2nd-GFCT) is presented. Whereafter, an ideal backward cloud transformation algorithm of the 2nd-order generic normal cloud model (2nd-GIBCT) is designed based on the mutually inverse features of FCT and BCT, in which the distribution of all the cloud drops generated in 2nd-GFCT is used. Meanwhile, a 2nd-order generic backward cloud transformation algorithm (2nd-GBCT), which does not use the distribution of cloud drops, is also proposed to solve real life problems since it is impossible to know the distribution of all the cloud drops in advance in real life applications. The relationships between the generic backward cloud transformation algorithms are further studied, which help reach the finding that the two backward cloud transformation algorithms presented by Wang and Xu [26,34] are two special cases of the 2nd-GBCT. In addition, the 2nd-order generic normal cloud model is further generalized to pth-order generic normal cloud model, and the pth-order generic forward normal cloud transformation algorithm (pth-GFCT) and the backward cloud transformation algorithm (pth-GBCT) are presented. Finally, the performances of the 2nd-GIBCT and the 2nd-GBCT are illustrated by simulation experiment. The effectiveness of the 2nd-GBCT is shown by the results of image segmentation. © 2014 Elsevier Inc. All rights reserved.

Ma X.,Southwest Jiaotong University | Ma X.,Chongqing University of Posts and Telecommunications | Wang G.,Chongqing University of Technology | Yu H.,Chongqing University of Posts and Telecommunications | Li T.,Southwest Jiaotong University
Information Sciences | Year: 2014

In the Pawlak rough set model, the positive region, the boundary region and the non-negative region are monotonic with respect to the set inclusion of attributes. However, the monotonicity property of the decision regions (positive region, boundary region or non-negative region) with respect to the set inclusion of attributes does not hold in the decision-theoretic rough set model. Therefore, the decision regions may be changed after attribute reduction based on quantitative preservation or qualitative preservation of decision regions. This effect is observed partly because three decision regions are defined by introducing the probabilistic threshold values. In addition, heuristic reduction algorithms based on decision regions may find super reducts because of the non-monotonicity of decision regions. To address the above issues, this paper proposes solutions to the attribute reduction problem based on decision region preservation in the decision-theoretic rough set model. First, the (α,β) positive region distribution preservation reduct, the (α,β) boundary region distribution preservation reduct and the (α,β) negative region distribution preservation reduct are introduced into the decision-theoretic rough set model. Second, three new monotonic measures are constructed by considering variants of the conditional information entropy, from which we can obtain the heuristic reduction algorithms. The results of the experimental analysis validate the monotonicity of new measures and verify the effectiveness of decision region distribution preservation reducts. © 2014 Elsevier Inc. All rights reserved.

Chen L.,Beijing University of Posts and Telecommunications | Chen W.,BUPT | Wang B.,BUPT | Zhang X.,BUPT | And 2 more authors.
IEEE Communications Magazine | Year: 2011

System-level simulation has been widely used to evaluate the comprehensive performance of different mobile cellular systems. System-level simulation methodologies for different systems have been discussed by different organizations and institutions. However, the framework for a unified simulation methodology and platform has not been established. In this article, we propose a general unified simulation methodology for different cellular systems. Both the design of the simulation structure and the establishment of the simulation platform are studied. Meanwhile, the unified modeling and the realization of various modules related to the system-level simulation are presented. The proposed unified simulation methodology and the general simulation platform can be used to evaluate the performance of multiple mobile communication systems fairly. Finally, the overall performance of LTE and Mobile WiMAX systems is evaluated through the proposed framework. The key simulation results for both Full Buffer and VoIP traffics are presented and discussed. It is shown that the LTE system exhibits better performance than Mobile WiMAX. © 2010 IEEE.

Li Q.,Southwest Jiaotong University | Chen W.,Southwest Jiaotong University | Liu Z.,Southwest Jiaotong University | Li M.,Tangshan Railway Vehicle Co. | Ma L.,Southwest Jiaotong University
Journal of Power Sources | Year: 2015

A hybrid powertrain configuration based on a proton exchange membrane (PEMFC), a battery and a supercapacitor (SC) is designed without grid connection for the LF-LRV tramway. In order to avoid rapid changes of power demand and achieve high efficiency without degrading the mechanism performance, a power sharing strategy based on a combination of fuzzy logic control (FLC) and Haar wavelet transform (Haar-WT) is proposed for an energy management system of the hybrid tramway. The results demonstrate that the proposed energy management system is able to ensure the major positive portion of the low frequency components of power demand can be deals with the PEMFC. The battery can help provide a portion of the positive low frequency components of power demand to reduce the PEMFC burden while the SC bank can supply all the high frequency components which could damage the PEMFC membrane. Therefore, the energy management system of high-power hybrid tramway is able to guarantee a safe operating condition with transient free for the PEMFC and extend the lifetime of each power source. Finally, the comparisons with other control strategies verify that the proposed energy management system can achieve better energy efficiency of the overall hybrid tramway. © 2014 Elsevier B.V. All rights reserved.

Cao W.,North China University of Water Conservancy and Electric Power | Liu J.,Southwest Jiaotong University
Journal of Multimedia | Year: 2012

Recognizing vehicle license plate image captured in low illumination place is a difficult problem. To solve the problem, this paper proposes a new license plate image enhancement method using bidimensional empirical mode decomposition (BEMD) technique. BEMD is a 2D data- driven adaptive nonlinear signal decomposition approach derived from the 1D empirical mode decomposition (EMD). In the proposed algorithm, the main procedures are designed as the following: first, the license plate image is denoised by the use of alpha-trimmed mean filter and transformed from RGB color space into HSV color space, then, extract the V component to form intensity image for enhancement; second, with BEMD method, the intensity image is decomposed into a number of intrinsic mode functions (IMF) as well as a residual image; last, the brightness of residual image is adjusted using Retinex theory, and fused with the IMF images to achieve enhancement of license plate image. Experimental results show the proposed method provides superior performance over traditional schemes for license plate image enhancement in low illumination. © 2012 ACADEMY PUBLISHER.

Luo M.-X.,Southwest Jiaotong University | Chen X.-B.,Beijing University of Posts and Telecommunications | Chen X.-B.,University of Chinese Academy of Sciences | Yang Y.-X.,Beijing University of Posts and Telecommunications | Niu X.-X.,Beijing University of Posts and Telecommunications
Quantum Information Processing | Year: 2012

Motivated by some previous joint remote preparation schemes, we first propose some quantum circuits and photon circuits that two senders jointly prepare an arbitrary one-qubit state to a remote receiver via GHZ state. Then, by constructing KAK decomposition of some transformation in SO(4), one quantum circuit is constructed for jointly preparing an arbitrary two-qubit state to the remote receiver. Furthermore, some deterministic schemes of jointly preparing one-qubit and two-qubit states are presented. Besides, the proposed schemes are extended to multi-sender and the partially entangled quantum resources. © 2011 Springer Science+Business Media, LLC.

News Article | November 29, 2016

CHENGDU, China, Nov 29, 2016 /PRNewswire/ -- The iF Design Awards in Germany, one of the most prestigious global design awards around the world, made its debut during Chengdu Creativity & Design Week 2016 from November 25 - 27. More than 700 award-winning products from 2016 were on display to the public in Chengdu, a western city of China. It is the first time that iF Award-winning products have been exhibited abroad. Chengdu, one of the Top Six National Central Cities in China, is the only one crowned as the Cultural and Creative Industry Center. By holding Creativity & Design Week, Chengdu brings in international resources and facilitates international cooperation. It aims to grow into a center city for world-class creative and design industries to exhibit, communicate and trade, where local designers can find an international creative and design platform, and where the world's leading design institutions can find plenty of reasons to come. Chengdu Creativity & Design Week (CCDW), established in 2014, is now one of the most renowned events in western and central China. This year, CCDW consisted of the 2016 Gold Panda Culture Creativity Design Awards, The 3rd Chengdu Creativity & Design Industry Expo, The Forum on International Culture Industries Chengdu Summit, China 2016, the 2016 Chengdu College Student Creative Design Competition, Dual-100 Cultural Tourism Creative Activities and an E-sports Competition. At the 3rd Chengdu Creativity & Design Industry Expo, three iF Award-winning products caught a lot of attention. They were the ThinkPad X1 Tablet, to which users could add functions depending on their needs; the HIDEOUT Lounge Chair made by steam bending technology, and the Black & Gray & Silber Scissors, which are simple and practical. The cooperation between iF and CCDW has covered more areas. The iF Design Awards judges, together with a lot of esteemed international and domestic experts, served as judges for the 2016 Gold Panda Culture Creativity Design Awards. They were Paul Cohen, one of the founders of Cube Design Australia; HIRO TANAKA, world-renowned designer and winner of the Red Dot Design Award for best designer in Germany; Guangmin Zhang, regional adviser for ICSID (International Council of Societies of Industrial Design); Xiaobo Lu, Dean of Tsinghua University Academy of Fine Arts and judge for the Red Dot Award; Bochu Xu, Dean of the Rail and Transportation College of Southwest Jiaotong University and expert in the field of rail transportation and bridges, and several others. At the 2016 Gold Panda Culture Creativity Design Awards, 159 awards in 9 categories and 5 special awards were selected. The Gold Panda Award is one of the highest awards for creative design in China, with a prize of RMB 1 million. The 12 prize-winning products from this year's Gold Panda Awards will attend the competition for the 2017 iF Design Awards in Germany. At present, iF International Forum Design, founders and organizer of the iF Product Design Awards, is discussing the possibility of further engagement in areas such as exhibitions, forums, counseling and training with the Chengdu government. The evaluation process on iF landing in Chengdu is under way. Ralph Wiegmann, CEO of iF International Forum Design, visited such cultural and creative design Industry sites as Chengdu Planning Exhibition Hall, Thinkzone International, and Eastern Suburb Memory from November 3 - 4. He highly commended Chengdu for its splendid, long history, reasonable city planning, and favorable environment for the cultural and creative design industries. "Such an environment can inspire the creativity of entrepreneurs, and Chengdu is an ideal place for iF to land," he said. At CCDW 2016's opening ceremony on November 25th, the Chengdu government and Cambridge Funds Investment Co., Ltd (Cambridge Funds) reached a cooperative consensus that out of its first batch of investment towards China (totaling RMB 3 billion), RMB 450 million will be set aside to invest in Chengdu's cultural and creative design industries. Cambridge Funds completed its first investment, RMB 300,000 for stone craft designed by Jiayong Luo, a 24-year-old man from Chongzhou, Chengdu, at the 3rd Chengdu Creativity & Design Industry Expo, which was a core part of CCDW 2016. To view the original version on PR Newswire, visit:

Ding C.,Hong Kong University of Science and Technology | Yang Y.,Southwest Jiaotong University | Tang X.,Southwest Jiaotong University
IEEE Transactions on Information Theory | Year: 2010

In communication systems, frequency hopping spread spectrum and direct sequence spread spectrum are two main spread coding technologies. Frequency hopping sequences are used in FH-CDMA systems. In this paper, an earlier idea of constructing optimal sets of frequency hopping sequences is further investigated. New optimal parameters of sets of frequency hopping sequences are obtained with subcodes of the ReedSolomon codes. Optimal sets of frequency hopping sequences are constructed with a class of irreducible cyclic codes. As a byproduct, the weight distribution of a subclass of irreducible cyclic codes is determined. © 2006 IEEE.

Ding C.,Hong Kong University of Science and Technology | Tang X.,Southwest Jiaotong University
IEEE Transactions on Information Theory | Year: 2010

Binary sequences with low correlation have applications in communication systems and cryptography. Though binary sequences with optimal autocorrelation were constructed in the literature, no pair of binary sequences with optimal autocorrelation are known to have also best possible cross correlation. In this paper, new bounds on the cross correlation of binary sequences with optimal autocorrelation are derived, and pairs of binary sequences having optimal autocorrelation and meeting some of these bounds are presented. These new bounds are better than the Sarwate bounds on the cross correlation of binary sequences with optimal autocorrelation. © 2006 IEEE.

Ding Z.,Newcastle University | Ma Z.,Southwest Jiaotong University | Ma Z.,Nanjing Southeast University | Fan P.,Southwest Jiaotong University
IEEE Transactions on Wireless Communications | Year: 2014

In this paper, we consider a two-way relaying scenario with one pair of source nodes, one relay and one eavesdropper. All nodes are equipped with multiple antennas, and we study the impact of antenna selection on such a secure communication scenario. Three transmission schemes with different tradeoff between secure performance and complexity are investigated respectively. Particularly, when antenna selection is implemented at the relay and no artificial noise is introduced, the condition to realize secure transmissions is established. Then by allowing the sources to inject artificial noise into the system, the secure performance is evaluated by focusing on different eavesdropping strategies. When both the relay and the sources send artificial noise, a low complexity strategy of antenna selection is proposed to efficiently utilize the antennas at the sources and the relay. The developed asymptotic results demonstrate that, by adding more artificial noise and performing joint antenna selection, a better secure performance, such as a larger secrecy rate and a lower outage probability, can be realized at a price of imposing more complexity on the system. Simulation results are also provided to demonstrate the accuracy of the developed analytical results. © 2002-2012 IEEE.

Tang X.,Southwest Jiaotong University | Ding C.,Hong Kong University of Science and Technology
IEEE Transactions on Information Theory | Year: 2010

Sequences with optimal autocorrelation property are needed in certain communication systems and cryptography. In this paper, a construction of balanced quaternary sequences with period N ≡ 2 (mod 4) and optimal autocorrelation value and a construction of almost balanced binary sequences with period N ≡ 0 (mod 4) and optimal autocorrelation value are presented. Both constructions are a generalization of earlier ones. © 2006 IEEE.

Li S.,Sichuan University | Liang Z.,Sichuan University | Xu L.,Southwest Jiaotong University | Zou F.,Sichuan University
Molecular and Cellular Biochemistry | Year: 2012

MiRNAs are a new class of small RNA molecules that regulate gene expression at the post-transcriptional and translational levels. MiRNAs have been implicated in the control of many vital biological processes including development, cell proliferation, differentiation, and apoptosis. A growing number of studies have shown that miRNAs also play an important role in carcinogenesis and other diseases. Among the miRNAs identified, miRNA-21 is dramatically up-regulated in cancer cells of various origins. It regulates a wide range of genes and pathways involved in cancer initiation, transformation, invasion, and metastasis. MiRNA-21 also acts as a pro-survival factor in cardiovascular diseases. Aberrant expression in these diseases makes miRNA-21 a potential marker for disease diagnosis and prognosis. This review highlights the complex roles that miRNA-21 plays in cancer and cardiovascular diseases and its potential clinical applications. © 2011 Springer Science+Business Media, LLC.

Guo Y.-N.,Southwest Jiaotong University | Lu X.,Southwest Jiaotong University | Weng J.,Southwest Jiaotong University | Leng Y.,Hong Kong University of Science and Technology
Journal of Physical Chemistry C | Year: 2013

This study investigated the interaction between carbon nanostructures, including pristine graphene, defective graphene with monovacancy, graphene oxide (GO), and tripeptide arginine-glycine-aspartic acid (RGD), by density functional theory. The results from the adsorption energy analysis show that the strongest adsorption is observed when RGD is parallel to graphene surfaces, in which graphene interacts with all three functional groups of RGD, including NH3+, COO-, and guanidine. The interaction of NH3+···π was stronger than that of guanidine-NH2···π and COO -···π. The vacancy improves the ability of graphene to attract RGD because of active dangling C atoms. GO has a stronger interaction with RGD than the pristine and defective graphene because of O-containing groups. The comparison of the GO model with the OH, epoxy, and mixed OH/epoxy groups reveals that various O-containing groups have distinguishing binding abilities with RGD. Water molecules strengthen the interactions between graphene and RGD, whereas they weaken the interaction between GO and RGD. The results provide useful guidance in designing optimal carbon nanomaterial surfaces with specific characteristics that could satisfy the demand for diverse applications of carbon nanomaterials in biomedical fields. © 2013 American Chemical Society.

Zhang Z.-D.,Shaanxi Normal University | Zhang Z.-D.,Southwest Jiaotong University | Wang H.-Y.,Southwest Jiaotong University | Zhang Z.-Y.,Shaanxi Normal University
Plasmonics | Year: 2013

The filter function of the metal-insulator-metal (MIM) waveguide with a gear-shaped nanocavity is investigated using the finite-difference time-domain method. Since the gear breaks the symmetric distribution of the resonance, Fano resonance occurs in the gear-shaped nanocavity. Fano resonance strongly depends on the structural parameters of the gear. Compared to the MIM waveguide with a disk-shaped nanocavity, the MIM waveguide with a gear-shaped nanocavity allows for a much more sensitive detection of small refractive index changes of the filled media inside the nanocavity, which reveals a potential sensor application of the MIM waveguide with a gear-shaped nanocavity. © 2012 Springer Science+Business Media New York.

Li C.,University of Bergen | Li N.,Southwest Jiaotong University | Helleseth T.,University of Bergen | Ding C.,Hong Kong University of Science and Technology
IEEE Transactions on Information Theory | Year: 2014

Let m ≥ 3 be an odd integer and p be an odd prime. In this paper, a number of classes of three-weight cyclic codes C(1,e) over F{double-struck}p, which have parity-check polynomial m 1(x)me(x), are presented by examining general conditions on the parameters p, m, and e, where mi(x) is the minimal polynomial of π-i over F{double-struck}p for a primitive element π of F{double-struck}pm. Furthermore, for p ≡ 3 (mod 4) and a positive integer e satisfying (pk + 1) · e ≡ 2 (mod pm - 1) for some positive integer k with gcd(m, k) = 1, the value distributions of the exponential sums T(a, b) = ∑ x∈F{double-struck}pm ωTr(ax+bxe) and S(a, b, c) = ∑x∈F{double-struck}pm ωTr(ax+bxe+cxs), where s = (pm - 1)/2, are determined. As an application, the value distribution of S(a, b, c) is utilized to derive the weight distribution of the cyclic codes C(1,e,s) with parity-check polynomial m 1(x)me(x)ms(x). In the case of p = 3 and even e satisfying the above condition, the dual of the cyclic code C(1,e,s) has optimal minimum distance. © 2014 IEEE.

Zhao Y.X.,Southwest Jiaotong University | Zhang B.,China Academy of Railway Sciences
Advanced Materials Research | Year: 2012

Causes are investigated on the earlier failures of the bearings for China railway freight cars with radial bogie. Through observing failure objects, checking manufacturing quality, and calculating rolling contact fatigue (RCF) stresses, it reveals that poor manufacturing quality of bearing outer ring plays a key role to the earlier failures and, in addition, mismatch design of RCF stresses between the outer ring and the inner ring acts as an aid actor. Checks verify that surface and core of the outer ring have lower hardness values than requirements; seldom micro-structures, i.e. black-white bands with thickness of around 0.6 to 1.3 mm, appear in the carburized layer of the bearing outer ring; the white part is needle like martensites with higher hardness values, while the black part is pearlites with lower hardness values; and more contingently, crack like manufacturing flaws may appear in the carburized layer with equiaxed grains of ferrites having lower hardness values are around the flaws. RCF values of the outer ring are much larger than that of the inner ring. But the equivalent RCF stress on the present car with radial bogie is lower than that on other cars. This indicates that main cases of the present earlier failures are due the bearings themselves other than the cars. © (2012) Trans Tech Publications, Switzerland.

Zhao Y.X.,Southwest Jiaotong University | Zhang B.,China Academy of Railway Sciences
Advanced Materials Research | Year: 2012

Causes are investigated on earlier failures of the bearings for China railway freight cars with tilting bogie. Through dissembling failure objects, checking manufacturing qualities and calculating rolling contact fatigue (RCF) stresses, it reveals that RCF plays a key role to the bearing failures. Design mismatch of the RCF stresses between outer and inner rings is main cause of the earlier failures of bearings. It is further verified that the present earlier failures of the bearings on the cars with tilting bogie than others on cars without tilting bogie is a reasonable phenomenon, because the wheelsets on the cars with the tilting are subjected to more severe loads. In addition, material manufacturing flaws, inhomogeneous force transferring circumstances, and seal leak may play an aided role to speed up the bearings failures. © (2012) Trans Tech Publications, Switzerland.

Zhang Y.,CAS Wuhan Institute of Rock and Soil Mechanics | Zhang W.,Southwest Jiaotong University
Science China Technological Sciences | Year: 2010

One kind of 3D coupled thermo-hydro-mechanical-migratory model for saturated-unsaturated dual-porosity medium was established, in which the stress field and the temperature field are single, but the seepage field and the concentration field are double, and the influences of sets, spaces, angles, continuity ratios, stiffness of fractures on the constitutive relationship of the medium can be considered. The relative three-dimensional program of finite element method was also developed. By comparing with the existing computation example, reliability of the model and the program were verified. Taking a hypothetical nuclear waste repository as a calculation example, the radioactive nuclide leak was simulated numerically with both the rock mass and the buffer being unsaturated media, and the temperatures, negative pore pressures, flow velocities, nuclide concentrations and normal stresses in the rock mass were investigated. The results showed that the temperatures, negative pore pressures and nuclide concentrations in the buffer all present nonlinear changes and distributions that even though the saturation degree in porosity is only about 1/9 of that in fracture, the flow velocity of underground water in fracture is about 6 times of that in porosity because the permeability coefficient of fracture is almost four orders higher than that of porosity, and that the regions of stress concentration occur at the vicinity of two sides of the boundary between buffer and disposal pit wall. © 2010 Science China Press and Springer-Verlag Berlin Heidelberg.

Zhou Z.,Southwest Jiaotong University | Ding C.,Hong Kong University of Science and Technology
Finite Fields and their Applications | Year: 2014

Cyclic codes are a subclass of linear codes and have applications in consumer electronics, data storage systems, and communication systems as they have efficient encoding and decoding algorithms. In this paper, a class of three-weight cyclic codes over Fp whose duals have two zeros is presented, where p is an odd prime. The weight distribution of this class of cyclic codes is settled. Some of the cyclic codes are optimal. The duals of a subclass of the cyclic codes are also studied and proved to be optimal. © 2013 Elsevier Inc.

Zhou Z.,Southwest Jiaotong University | Zhou Z.,Xidian University | Ding C.,Hong Kong University of Science and Technology | Luo J.,University of Bergen | Zhang A.,Xi'an University of Technology
IEEE Transactions on Information Theory | Year: 2013

Cyclic codes are a subclass of linear codes and have applications in consumer electronics, data storage systems, and communication systems as they have efficient encoding and decoding algorithms. In this paper, a family of $p$-ary cyclic codes whose duals have three pairwise nonconjugate zeros is proposed. The weight distribution of this family of cyclic codes is determined. It turns out that the proposed cyclic codes have five nonzero weights. © 1963-2012 IEEE.

Ding C.,Hong Kong University of Science and Technology | Gao Y.,Beihang University | Zhou Z.,Southwest Jiaotong University
IEEE Transactions on Information Theory | Year: 2013

As a subclass of linear codes, cyclic codes have applications in consumer electronics, data storage systems, and communication systems as they have efficient encoding and decoding algorithms. In this paper, five families of three-weight ternary cyclic codes whose duals have two zeros are presented. The weight distributions of the five families of cyclic codes are settled. The duals of two families of the cyclic codes are optimal. © 1963-2012 IEEE.

Kang G.,Southwest Jiaotong University | Yan W.,Monash University
Philosophical Magazine | Year: 2010

Based on dimensional analysis and finite element calculations, several scaling relationships in the indentation of shape memory alloys with a sharp conical indenter were obtained. These scaling relationships illustrate the dependence of the indentation response on the material properties of shape memory alloys, such as phase transition and plastic deformation. It is shown that the yield stress and strain-hardening exponent of transformed martensite play important roles in the indentation response, in addition to the phase transition properties. Additionally, the general relationships between indentation hardness and phase transition stress, maximum transition strain, martensite yield stress and the strain-hardening exponent of shape memory alloys were obtained. The results show that the indentation hardness of shape memory alloys is not proportional to the phase transition stress or to the martensite yield stress, and cannot be used directly to measure the phase transition stress or the yield stress of shape memory alloys.

Zhan Y.-X.,CAS Wuhan Institute of Rock and Soil Mechanics | Zhan Y.-X.,Chongqing University | Jiang G.-L.,Southwest Jiaotong University
Yantu Lixue/Rock and Soil Mechanics | Year: 2010

Based on Suining-Chongqing high speed railway, the dynamic characteristics of ballastless track soil subgrade are analyzed through an indoor large-scale model test under dynamic loading. The result indicates that along the subgrade surface cross section, dynamic responses have the W-shaped distribution. But gradually become the basin-shaped distribution with the increase of depth. The largest dynamic response measured are under the concrete track position base, while the responses under the centre-line and the two ends of the concrete slab are smaller. The most intense dynamic responses are measured on the surface and graded gravel area; it reduces sharply with the increase of depth. Dynamic stress is slightly affected by loading frequency, while acceleration and dynamic deformation are fairly affected by it. In addition, a comprehensive field test has been conducted on the test course in Suining-Chongqing line by using CRH2-EMUs and freight train. The dynamic response of ballastless track subgrade under diffident speeds have been collected and the dynamic characteristics are analyzed. The results verify the suitability and adaptability of subgrade construction on Suining-Chongqing line.

Zhang Y.-J.,CAS Wuhan Institute of Rock and Soil Mechanics | Zhang W.-Q.,Southwest Jiaotong University
Yantu Lixue/Rock and Soil Mechanics | Year: 2010

In order to consider the composite impact of mechanical dilation/compaction and pressure solution on fracture aperture, the coupled thermo-hydro-mechanical model for dual-porosity medium established by the first author was improved. Taking a hypothetical nuclear waste repository as a calculation example, three coupled THM cases in which fracture aperture changes with different patterns were simulated numerically by FEM. The variations and distributions of temperatures, pore (fracture) pressures, flow velocities of underground water and normal stresses in the rock mass were investigated. The results show: the temperature fields of three cases are near the same; the forms of seepage fields of three cases are similar; but their quantity values have some differences; the closure degree of fracture apertures under the combined action of stress and pressure solution in case 1 is the maxmium one; so the negative pore pressures in this case are the highest; the liberated heat from vitrified waste changes obviously the horizontal component of gravity stress field of rock mass, but exerts smaller effect on the vertical component.

Zhang S.-C.,Southwest Jiaotong University | Thumm M.,Karlsruhe Institute of Technology
Physics Letters, Section A: General, Atomic and Solid State Physics | Year: 2010

The cyclotron autoresonance maser (CARM) operating in a transverse-magnetic (TM) wave by employing a large-orbit relativistic electron beam shows a peculiarity that the growth rate range of coherent amplification of the TM wave is split into two branches as the electrons' cyclotron frequency increases: the upper branch is quite favorable to terahertz operation, whereas the lower branch can lead to a backward-wave CARM mechanism which is suitable to sub-terahertz operation. Compared to a terahertz large-orbit transverse-electric-wave gyrotrons and gyro-amplifiers which are experimentally realized up to date, a terahertz large-orbit TM-wave CARM requires much lower operating magnetic field and allows the cavity to have larger transverse dimension. © 2010 Elsevier B.V. All rights reserved.

Fan W.,University of Edinburgh | Fan W.,Beihang University | Wang X.,Southwest Jiaotong University | Wu Y.,University of California at Santa Barbara
Proceedings - International Conference on Data Engineering | Year: 2014

Answering queries using views has proven an effective technique for querying relational and semistructured data. This paper investigates this issue for graph pattern queries based on (bounded) simulation, which have been increasingly used in, e.g., social network analysis. We propose a notion of pattern containment to characterize graph pattern matching using graph pattern views. We show that a graph pattern query can be answered using a set of views if and only if the query is contained in the views. Based on this characterization we develop efficient algorithms to answer graph pattern queries. In addition, we identify three problems associated with graph pattern containment. We show that these problems range from quadratic-time to NP-complete, and provide efficient algorithms for containment checking (approximation when the problem is intractable). Using real-life data and synthetic data, we experimentally verify that these methods are able to efficiently answer graph pattern queries on large social graphs, by using views. © 2014 IEEE.

Fan W.,University of Edinburgh | Fan W.,Beihang University | Wang X.,Southwest Jiaotong University | Wu Y.,University of California at Santa Barbara
Proceedings of the ACM SIGMOD International Conference on Management of Data | Year: 2014

This paper studies the problem of querying graphs within bounded resources. Given a query Q, a graph G and a small ratio α, it aims to answer Q in G by accessing only a fraction GQ of G of size |GQ| ≤ α|G|. The need for this is evident when G is big while our available resources are limited, as indicated by α. We propose resource-bounded query answering via a dynamic scheme that reduces big G to GQ. We investigate when we can find the exact answers Q(G) from GQ, and if GQ cannot accommodate enough information, how accurate the approximate answers Q(GQ) are. To verify the effectiveness of the approach, we study two types of queries. One consists of pattern queries that have data locality, such as subgraph isomorphism and strong simulation. The other is the class of reachability queries, without data locality. We show that it is hard to get resource-bounded algorithms with 100% accuracy: NP-hard for pattern queries, and non-existing for reachability when α 6≠ 1. Despite these, we develop resource-bounded algorithms for answering these queries. Using real-life and synthetic data, we experimentally evaluate the performance of the algorithms. We find that they scale well for both types of queries, and our approximate answers are accurate, even 100% for small α. © 2014 ACM.

Kan Q.,Southwest Jiaotong University | Yan W.,Monash University | Kang G.,Southwest Jiaotong University | Sun Q.,Hong Kong University of Science and Technology
Journal of the Mechanics and Physics of Solids | Year: 2013

Instrumented indentation test has been extensively applied to study the mechanical properties such as elastic modulus of different materials. The Oliver-Pharr method to measure the elastic modulus from an indentation test was originally developed for single phase materials. During a spherical indentation test on shape memory alloys (SMAs), both austenite and martensite phases exist and evolve in the specimen due to stress-induced phase transformation. The question, "What is the measured indentation modulus by using the Oliver-Pharr method from a spherical indentation test on SMAs?" is answered in this paper. The finite element method, combined with dimensional analysis, was applied to simulate a series of spherical indentation tests on SMAs. Our numerical results indicate that the measured indentation modulus strongly depends on the elastic moduli of the two phases, the indentation depth, the forward transformation stress, the transformation hardening coefficient and the maximum transformation strain. Furthermore, a method based on theoretical analysis and numerical simulation was established to determine the elastic moduli of austenite and martensite by using the spherical indentation test and the Oliver-Pharr method. Our numerical experiments confirmed that the proposed method can be applied in practice with satisfactory accuracy. The research approach and findings can also be applied to the indentation of other types of phase transformable materials. © 2013 Elsevier Ltd.

Chen X.,Kunming University of Science and Technology | Chen X.,Southwest Jiaotong University | Zhang J.,Southwest Jiaotong University | Li D.,Southwest Jiaotong University
IEEE Transactions on Image Processing | Year: 2012

Discriminant locality preserving projection (DLPP) is a linear approach that encodes discriminant information into the objective of locality preserving projection and improves its classification ability. To enhance the nonlinear description ability of DLPP, we can optimize the objective function of DLPP in reproducing kernel Hilbert space to form a kernel-based discriminant locality preserving projection (KDLPP). However, KDLPP suffers the following problems: 1) larger computational burden; 2) no explicit mapping functions in KDLPP, which results in more computational burden when projecting a new sample into the low-dimensional subspace; and 3) KDLPP cannot obtain optimal discriminant vectors, which exceedingly optimize the objective of DLPP. To overcome the weaknesses of KDLPP, in this paper, a direct discriminant locality preserving projection with Hammerstein polynomial expansion (HPDDLPP) is proposed. The proposed HPDDLPP directly implements the objective of DLPP in high-dimensional second-order Hammerstein polynomial space without matrix inverse, which extracts the optimal discriminant vectors for DLPP without larger computational burden. Compared with some other related classical methods, experimental results for face and palmprint recognition problems indicate the effectiveness of the proposed HPDDLPP. © 1992-2012 IEEE.

Zhu S.,Southwest Jiaotong University | Zhu S.,Rice University | Cai C.,Southwest Jiaotong University
Engineering Failure Analysis | Year: 2014

The stress intensity factors (SIFs) for through-transverse crack in the China Railway Track System (CRTS II) slab track system under vehicle dynamic load are evaluated in this paper. A coupled dynamic model of a half-vehicle and the slab track is presented in which the half-vehicle is treated as a 18-degree-of-freedom multi-body system. The slab track is modeled as two continuous Bernoulli-Euler beams supported by a series of elastic rectangle plates on a viscoelastic foundation. The model is applied to calculate the vertical and lateral dynamic wheel-rail forces. A three-dimensional finite element model of the slab track system is then established in which the through-transverse crack at the bottom of concrete base is created by using extended finite element method (XFEM). The wheel-rail forces obtained by the vehicle-track dynamics calculation are utilized as the inputs to finite element model, and then the values of dynamic SIFs at the crack-tip are extracted from the XFEM solution by domain based interaction integral approach. The influences of subgrade modulus, crack length, crack angle, friction coefficient between cracked surfaces, and friction coefficient between faces of concrete base and subgrade on dynamic SIFs are investigated in detail. The analysis indicates that the subgrade modulus, crack length and crack angle have great effects on dynamic SIFs at the crack-tip, while both of the friction coefficients have negligible influences on variations of dynamic SIFs. Also the statistical characteristics of varying SIFs due to random wheel-rail forces are studied and results reveal that the distributions of dynamic SIFs follow an approximately Gaussian distribution with different mean values and standard deviations. The numerical results obtained are very useful in the maintenance of the slab track system. © 2014 Elsevier Ltd.

Cui S.,Southwest Jiaotong University | Pang X.,Southwest Jiaotong University | Zhang S.,CAS Suzhou Institute of Nano Technology and Nano Bionics | Yu Y.,Southwest Jiaotong University | And 2 more authors.
Langmuir | Year: 2012

Poly(N-isopropyl-acrylamide) (PNIPAM) is a paradigm thermally sensitive polymer, which has a lower critical solution temperature (LCST) of ∼32 °C in water. Herein by AFM-based single molecule force spectroscopy (SMFS), we measured the single chain elasticity of PNIPAM across the LCST in water. Below LCST, the force curves obtained at different temperatures have no remarkable difference; while above LCST, an unexpected temperature dependent elasticity is observed, mainly in the middle force regime. We found that 35 °C is a turning point of the variation: from 31 to 35 °C, the middle parts of the force curves drop gradually, whereas from 35 to 40 °C, the middle parts rise gradually. A possible mechanism for the unexpected temperature dependent mechanics is proposed. The single chain contraction against external force upon heating from 35 to 40 °C may cast new light on the design of molecular devices that convert thermal energy to mechanical work. © 2012 American Chemical Society.

Lei D.,Wuhan University of Technology | Guo X.,Southwest Jiaotong University
International Journal of Production Research | Year: 2013

We consider lot streaming problem in a job shop with consistent sub-lots and transportation, in which each lot is regarded as an individual job to reduce management complexity. A modified artificial bee colony (MABC) algorithm is proposed to minimise makespan. An effective two-phase decoding procedure is applied, in which a schedule is first built and then transportation tasks are dispatched. A swap and an insertion are used in the employed bee phase and the onlooker bee phase respectively to produce new solutions. No scouts are considered and the worst solution is replaced with the elite solution every certain cycles to enhance the diversity of the swarm. The testing results and the comparisons of MABC with some methods show that MABC performs better than the chosen algorithms on the considered problem. © 2013 Taylor and Francis Group, LLC.

Zhu S.,Southwest Jiaotong University | Zhu S.,Rice University | Cai C.,Southwest Jiaotong University
International Journal of Non-Linear Mechanics | Year: 2014

This paper presents a three-dimensional finite element model to investigate the interface damage occurred between prefabricated slab and CA (cement asphalt) mortar layer in the China Railway Track System (CRTS-II) slab track system. In the finite element model, a cohesive zone model with a non-linear constitutive law is introduced and utilized to model the damage, cracking and delamination at the interface. Combining with the temperature field database obtained from the three-dimensional transient heat transfer analysis, the interface damage evolution as a result of temperature change is analyzed. A three-dimensional coupled dynamic model of a vehicle and the slab track is then established to calculate the varying rail-supporting forces which are utilized as the inputs to the finite element model. The non-linearities of the wheel-rail contact geometry, the wheel-rail normal contact force and the wheel-rail tangential creep force are taken into account in the model. Setting the maximum interface damaged state calculated under temperature change as the initial condition, the interface damage evolution and its influence on the dynamic response of the slab track are investigated under the joint action of the temperature change and vehicle dynamic load. The analysis indicates that the proposed model is capable of predicting the initiation and propagation of cracks at the interface. The prefabricated slab presents lateral warping, resulting in severe interface damage on both the sides of the slab track along the longitudinal direction during temperature drop process, while the interface damage level does not change significantly under vehicle dynamic loads. The interface damage has great effects on the dynamic responses of the slab track. © 2013 Elsevier Ltd.

Zhang M.,Southwest Jiaotong University | Wei L.F.,Southwest Jiaotong University | Wei L.F.,Sun Yat Sen University
Physical Review B - Condensed Matter and Materials Physics | Year: 2012

We propose an approach to entangle spins of electrons floating on liquid helium by coherently manipulating their spin-orbit interactions. The configuration consists of single electrons, confined individually on liquid helium by the microelectrodes, moving along the surface as the harmonic oscillators. It has been known that the spin of an electron could be coupled to its orbit (i.e., the vibrational motion) by properly applying a magnetic field. Based on this single electron spin-orbit coupling, here we show that a Jaynes-Cummings (JC) type interaction between the spin of an electron and the orbit of another electron at a distance could be realized via the strong Coulomb interaction between the electrons. Consequently, the proposed JC interaction could be utilized to realize a strong orbit-mediated spin-spin coupling and implement the desirable quantum information processing between the distant electrons trapped individually on liquid helium. © 2012 American Physical Society.

Lei D.,Wuhan University of Technology | Guo X.,Southwest Jiaotong University
Computers and Operations Research | Year: 2016

Previous studies of two-sided assembly line balancing problem (TALBP) are mainly about the first type of the problem.TALBP-II which is to minimize cycle time for a given number of stations is seldom investigated. In this study an effective variable neighborhood search (VNS) is proposed to solve TALBP-II. A novel two-string representation is used, which is composed of a precedence- based task string and a side selection string. New solutions are produced by using a side selection operator and two precedence-based operators. A novel comparison principle is applied to guarantee the feasibility of the solutions and approximate the optimal solution. VNS is tested on a number of instances and compared with the existing methods. The computational results show the promising advantage of VNS on the considered TALBP-II. © 2016 Elsevier Ltd.

Yan C.-H.,Sichuan Normal University | Wei L.-F.,Southwest Jiaotong University | Wei L.-F.,Sun Yat Sen University
Optics Express | Year: 2015

An external mirror coupling to a cavity with a two-level atom inside is put forward to control the photon transport along a one-dimensional waveguide. Using a full quantum theory of photon transport in real space, it is shown that the Rabi splittings of the photonic transmission spectra can be controlled by the cavity-mirror couplings; the splittings could still be observed even when the cavity-atom system works in the weak coupling regime, and the transmission probability of the resonant photon can be modulated from 0 to 100%. Additionally, our numerical results show that the appearance of Fano resonance is related to the strengths of the cavity-mirror coupling and the dissipations of the system. An experimental demonstration of the proposal with the current photonic crystal waveguide technique is suggested. © 2015 Optical Society of America.

Gu S.T.,Southwest Jiaotong University | Monteiro E.,University Paris Est Creteil | He Q.C.,Southwest Jiaotong University | He Q.C.,University Paris Est Creteil
Composites Science and Technology | Year: 2011

In a great number of situations of practical interest, the interfaces between the constituent phases of a composite turn out to be imperfect. In the context of thermal conduction, an interface is said to be imperfect if the requirement that both the temperature and the normal heat flux be continuous across the interface is not satisfied. A powerful method based on mathematical asymptotic analysis has been proposed and developed in the literature by several authors for the derivation of linear imperfect interface models of thermal conduction. This method consists in replacing an interphase of small uniform thickness between two-phases by an imperfect interface of null thickness characterized by the temperature and normal heat flux jump relations deduced by carrying out an appropriate asymptotic analysis. The objective of the present work is threefold. Firstly, it aims to explicitly show and emphasize the key role played by Hadamard's relation in the method. Secondly, it has the purpose of using a coordinate-free differential geometry theory and Hadamard's relation to render the method coordinate-free. Thirdly and most importantly, the present work gives a weak formulation for the problem concerning the steady thermal conduction in a composite with the interfaces described by the general temperature and normal heat flux jump relations derived. This weak formulation is a key step toward solving the problem by the extended finite element method (XFEM) presented in a companion paper. © 2011 Elsevier Ltd.

Lei D.,Wuhan University of Technology | Guo X.,Southwest Jiaotong University
International Journal of Production Research | Year: 2012

Fuzziness and flexibility are the features of most production processes; however, the scheduling problems with both flexible process plans and fuzzy processing conditions are not investigated fully for high complexity. This paper proposes an efficient swarm-based neighbourhood search algorithm (SNSA) for the fuzzy flexible job shop scheduling problem. In SNSA, ordered operation-based representation is used to indicate the solution of operation sequence sub-problem and machine assignment sub-problem is converted into a cell formation one, in which machines are regarded as cells and operations are allocated into cells. In each generation, two swaps, an insertion and tournament selection are applied to update swarms. Some numerical experiments are conducted by using some instances to show the effectiveness of SNSA. Computational results show that SNSA performs better than the existing methods from literature. © 2012 Copyright Taylor and Francis Group, LLC.

Guo Y.,Southwest Jiaotong University | Yan L.,Southwest Jiaotong University | Pan W.,Southwest Jiaotong University | Luo B.,Southwest Jiaotong University | And 3 more authors.
Optics Express | Year: 2012

We investigate a plasmonic waveguide system based on sidecoupled complementary split-ring resonators (CSRR), which exhibits electromagnetically induced transparency (EIT)-like transmission. LC resonance model is utilized to explain the electromagnetic responses of CSRR, which is verified by simulation results of finite difference time domain method. The electromagnetic responses of CSRR can be flexible handled by changing the asymmetry degree of the structure and the width of the metallic baffles. Cascaded CSRRs also have been studied to obtain EITlike transmission at visible and near-infrared region, simultaneously. © 2012 Optical Society of America.

Li W.-A.,Sun Yat Sen University | Wei L.-F.,Sun Yat Sen University | Wei L.-F.,Southwest Jiaotong University
Optics Express | Year: 2012

By using quantum Zeno dynamics, we propose a controllable approach to deterministically generate tripartite GHZ states for three atoms trapped in spatially separated cavities. The nearest-neighbored cavities are connected via optical fibers and the atoms trapped in two ends are tunably driven. The generation of the GHZ state can be implemented by only one step manipulation, and the EPR entanglement between the atoms in two ends can be further realized deterministically by Von Neumann measurement on the middle atom. Note that the duration of the quantum Zeno dynamics is controllable by switching on/off the applied external classical drivings and the desirable tripartite GHZ state will no longer evolve once it is generated. The robustness of the proposal is numerically demonstrated by considering various decoherence factors, including atomic spontaneous emissions, cavity decays and fiber photon leakages, etc. Our proposal can be directly generalized to generate multipartite entanglement by still driving the atoms in two ends. © 2012 Optical Society of America.

Zeng Q.,Southwest Jiaotong University | Zeng Q.,University of Tennessee at Knoxville | Li H.,University of Tennessee at Knoxville | Peng D.,Southwest Jiaotong University
IEEE Transactions on Smart Grid | Year: 2012

Smart grid is a modern infrastructure for improving the efficiency and reliability of power grid by integrating automated control, sensing and metering technologies, modern communication infrastructure and modern energy management techniques. Security and quality-of-service (QoS) are two most critical requirements for the communications network in smart grid. Frequency hopping (FH) technology, due to its inherent security, is a promising candidate technology in the physical layer of smart gird communication infrastructure. Unfortunately, all the existing FH systems can support only a single level of QoS due to the fact that traditional FH sequence sets can provide the same level of Hamming cross-correlation. In this paper, an FH-based communication network is developed for smart grid, particularly the advanced smart metering (AMI), to address the above two key challenges. A novel type of FH sequence set which meets the multi-level QoS requirement is designed. Then, the data traffic in AMI is investigated and modeled as a general Poisson process which is validated by real measurements of power consumptions. With the proposed sequence set and data model, the analytic performance in terms of error probabilities for the proposed FH communication with $M$-ary frequency-shift keying (FSK) modulation is derived for a slow Rayleigh fading channel. The analytic results are validated by numerical simulation results. © 2010-2012 IEEE.

Guo Y.,Southwest Jiaotong University | Yan L.,Southwest Jiaotong University | Pan W.,Southwest Jiaotong University | Luo B.,Southwest Jiaotong University | And 4 more authors.
Optics Express | Year: 2011

A plasmonic splitter based on slot cavity is proposed and numerically investigated using finite-difference-time-domain (FDTD) methods. The structure consists of the input waveguide, a slot cavity and output waveguides. By varying positions of output waveguides, frequency splitter and power splitter can be achieved in the proposed structure. Flexible output power ratio is feasible through further adjusting the coupling distance and the refractive index of output waveguides. © 2011 Optical Society of America.

Bao Y.,Southwest Jiaotong University | Qian H.-J.,Jilin University | Lu Z.-Y.,Jilin University | Cui S.,Southwest Jiaotong University
Nanoscale | Year: 2014

At crystal or larger scales, natural cellulose was generally recognized to be a rigid material. Our single-chain mechanical measurements, however, reveal that the natural cellulose is as flexible as common synthetic polymers at the single-chain level, creating new opportunities in the designing of nano materials. This journal is © The Royal Society of Chemistry.

Chen J.,Sun Yat Sen University | Wei L.F.,Sun Yat Sen University | Wei L.F.,Southwest Jiaotong University
Physical Review A - Atomic, Molecular, and Optical Physics | Year: 2015

Fast Rabi π-pulse technique has been widely applied to various coherent quantum manipulations, although it requires precise designs of the pulse areas. Relaxing the precise pulse designs, various rapid adiabatic passage (RAP) approaches have been alternatively utilized to implement various population passages deterministically. However, the usual RAP protocol could not be implemented desirably fast, as the relevant adiabatic condition should be robustly satisfied during the passage. Here, we propose a modified shortcut to adiabaticity (STA) technique to accelerate significantly the desired deterministic quantum state population passages. This transitionless technique is beyond the usual rotating wave approximation (RWA) performed in the recent STA protocols, and thus can be applied to deliver various fast quantum evolutions wherein the relevant counter-rotating effects cannot be neglected. The proposal is demonstrated specifically with the driven two- and three-level systems. Numerical results show that with the present STA technique beyond the RWA the usual Stark-chirped RAPs and stimulated Raman adiabatic passages could be significantly speeded up; the deterministic population passages could be implemented as fast as the widely used fast Rabi π pulses, but are insensitive to the applied pulse areas. © 2015 American Physical Society.

Feng L.,Agency for Science, Technology and Research Singapore | Monterola C.P.,Agency for Science, Technology and Research Singapore | Hu Y.,Southwest Jiaotong University | Hu Y.,Sun Yat Sen University
New Journal of Physics | Year: 2015

Interdependent networks in areas ranging from infrastructure to economics are ubiquitous in our society, and the study of their cascading behaviors using percolation theory has attracted much attention in recent years. To analyze the percolation phenomena of these systems, different mathematical frameworks have been proposed, including generating functions and eigenvalues, and others. These different frameworks approach phase transition behaviors from different angles and have been very successful in shaping the different quantities of interest, including critical threshold, size of the giant component, order of phase transition, and the dynamics of cascading. These methods also vary in their mathematical complexity in dealing with interdependent networks that have additional complexity in terms of the correlation among different layers of networks or links. In this work, we review a particular approach of simple, self-consistent probability equations, and we illustrate that this approach can greatly simplify the mathematical analysis for systems ranging from single-layer network to various different interdependent networks. We give an overview of the detailed framework to study the nature of the critical phase transition, the value of the critical threshold, and the size of the giant component for these different systems. © 2015 IOP Publishing Ltd and Deutsche Physikalische Gesellschaft.

Gu S.T.,Southwest Jiaotong University | He Q.C.,Southwest Jiaotong University | He Q.C.,University Paris Est Creteil
Journal of the Mechanics and Physics of Solids | Year: 2011

Interfacial continuity and discontinuity relations are needed in dealing with a variety of mechanical and physical phenomena in heterogeneous media. The present work consists of two parts. In the first part concerned with perfect interfaces, two orthogonal projection operators reflecting the interfacial continuity and discontinuity of the field variables of coupled mechanical and physical phenomena are introduced and some coordinate-free interfacial relations involving the surface decomposition of a generic linear constitutive law are deduced. In the second part dedicated to the derivation of a general imperfect interface model for coupled multifield phenomena by applying Taylor's expansion to a 3D curved thin interphase perfectly bonded to its two neighboring phases, the interfacial operators and relations given in the first part are used directly so as to render the derivation more direct and to write the final interfacial jump relations characterizing the model in a unified and compact way. The general imperfect interface model obtained in the present work includes as special cases all the relevant ones reported in the literature. © 2011 Elsevier Ltd. All rights reserved.

Lei D.,Wuhan University of Technology | Guo X.,Southwest Jiaotong University
International Journal of Production Research | Year: 2014

Dual-resource constrained flexible job shop scheduling problem (FJSP) is considered and an effective variable neighbourhood search (VNS) is presented, in which the solution to the problem is indicated as a quadruple string of the ordered operations and their resources. Two neighbourhood search procedures are sequentially executed to produce new solutions for two sub-problems of the problem, respectively. The search of VNS is restarted from a slightly perturbed version of the current solution of VNS when the determined number of iterations is reached. VNS is tested on some instances and compared with methods from literature. Computational results show the significant advantage of VNS on the problem. © 2013 © 2013 Taylor & Francis.

Lei D.,Wuhan University of Technology | Guo X.,Southwest Jiaotong University
International Journal of Production Economics | Year: 2015

In this study, scheduling problem in dual-resource constrained (DRC) job shop with interval processing time and heterogeneous resources is investigated. A lexicographical method is applied to minimize interval carbon footprint and makespan. A dynamical neighborhood search (DNS) is proposed, which is composed of two phases. Two-string representation is used and its chromosome consists of the operation-based string and the resource string. Several initial solutions are produced and improved in the first phase and only one solution is applied in the second phase. Four neighborhood structures and their dynamical transition mechanism are utilized to produce new solutions. DNS is tested on a number of instances and compared with other algorithms. Computational experiments show DNS can provide the promising results for the problem. © 2014 Elsevier B.V. All rights reserved.

Geng W.,Southwest Jiaotong University | Qiu M.,IBM | Zhao X.,Tsinghua University
International Journal of Production Economics | Year: 2010

We consider a single-distributor multi-retailer inventory system in six operating scenarios for a finite horizon. Five scenarios are in decentralized control and the other one is in centralized control. Approximate dynamic programming (ADP) procedures are developed to obtain system performances for scenarios in decentralized control, and a stochastic dynamic programming approach is applied to the scenario in centralized control. The efficiency and effectiveness of ADP procedures are demonstrated by numerical results. Taking the system performance in centralized control as a benchmark, system performances in decentralized control are investigated and compared for different operating scenarios. The results provide useful insights in system planning and operations. © 2010 Elsevier B.V.All rights reserved.

Meng D.,Southwestern University of Finance and Economics | Zhang X.,Shanghai Maritime University | Qin K.,Southwest Jiaotong University
Computers and Mathematics with Applications | Year: 2011

Fuzzy set theory, soft set theory and rough set theory are mathematical tools for dealing with uncertainties and are closely related. Feng et al. introduced the notions of rough soft set, soft rough set and soft rough fuzzy set by combining fuzzy set, rough set and soft set all together. This paper is devoted to the further discussion of the combinations of fuzzy set, rough set and soft set. A new soft rough set model is proposed and its properties are derived. Furthermore, fuzzy soft set is employed to granulate the universe of discourse and a more general model called soft fuzzy rough set is established. The lower and upper approximation operators are presented and their related properties are surveyed. © 2011 Elsevier Ltd. All rights reserved.

Luo X.,CAS Chengdu Institute of Optics and Electronics | Yan L.,Southwest Jiaotong University
IEEE Photonics Journal | Year: 2012

Surface plasmon polaritons (SPPs) have become one of the most rapidly expanding fields in photonics today. Exciting advances were made in research on SPPs in 2011. This review summarizes the significant progress and major achievements of super-resolution imaging, SPP lithography, SPP-assisted absorption, SPP-based antennas, light manipulation, and the current state-of-the-art in loss-compensation and process. The potential applications, future challenges, and opportunities are also discussed. © 2012 IEEE.

Liu D.,Southwest Jiaotong University | Li T.,Southwest Jiaotong University | Ruan D.,Belgian Nuclear Research Center | Ruan D.,Ghent University
Information Sciences | Year: 2011

In dealing with risk in real decision problems, decision-theoretic rough sets with loss functions aim to obtain optimization decisions by minimizing the overall risk with Bayesian decision procedures. Two parameters generated by loss functions divide the universe into three regions as the decision of acceptance, deferment and rejection. In this paper, we discuss the semantics of loss functions, and utilize the differences of losses replace actual losses to construct a new "four-level" approach of probabilistic rules choosing criteria. Ten types of probabilistic rough set models can be generated by the "four-level" approach and form two groups of models: two-way probabilistic decision models and three-way probabilistic decision models. A reasonable decision with these criteria is demonstrated by an illustration of oil investment. © 2011 Elsevier Inc. All rights reserved.

Hu Y.,City College of New York | Hu Y.,Southwest Jiaotong University | Havlin S.,Bar - Ilan University | Makse H.A.,City College of New York
Physical Review X | Year: 2014

A fundamental problem in network science is to predict how certain individuals are able to initiate new networks to spring up "new ideas." Frequently, these changes in trends are triggered by a few innovators who rapidly impose their ideas through "viral" influence spreading, producing cascades of followers and fragmenting an old network to create a new one. Typical examples include the rise of scientific ideas or abrupt changes in social media, like the rise of Facebook to the detriment of Myspace. How this process arises in practice has not been conclusively demonstrated. Here, we show that a condition for sustaining a viral spreading process is the existence of a multiplex-correlated graph with hidden "influence links." Analytical solutions predict percolation-phase transitions, either abrupt or continuous, where networks are disintegrated through viral cascades of followers, as in empirical data. Our modeling predicts the strict conditions to sustain a large viral spreading via a scaling form of the local correlation function between multilayers, which we also confirm empirically. Ultimately, the theory predicts the conditions for viral cascading in a large class of multiplex networks ranging from social to financial systems and markets.

Huang Z.W.,Southwest Jiaotong University | Huang Z.W.,University of Birmingham
Intermetallics | Year: 2013

A near lamellar γ-TiAl alloy Ti-44Al-4Nb-4Zr-0.2Si-1B was ingot cast and exposed at 700°C for up to 10,000 h. The combined addition of Nb and Zr rather than Nb alone has a positive effect on stabilization of α2 lamellae. Compared to alloy Ti-44Al-8Nb-1B, less amount of α2 dissolved and less amount of β (B2 + ω) formed in the alloy after the same exposure scheme. However, the exposure-induced embrittlement is still severe in this alloy. The ductility after 10,000-h exposure is only 1/4 of the original value. The exposure-induced embrittlement is attributed to the profound changes in prior β regions: the precipitation of fine D88-ω particles in the B82-ω matrix; the prevalent formation of γ grains inside the prior β regions; and the widespread precipitation of silicide particles at cell interfaces and β grain boundaries. The tensile strengths remain essentially unchanged while fatigue limit increased significantly. The mechanism behind the microstructural changes and mechanical properties is discussed in detail. © 2013 Elsevier Ltd. All rights reserved.

Zhang J.W.,Southwest Jiaotong University | Lu L.T.,Southwest Jiaotong University | Shiozawa K.,University of Toyama | Zhou W.N.,Chengdu Surface Metal Technology Co. | Zhang W.H.,Southwest Jiaotong University
International Journal of Fatigue | Year: 2011

The 35CrMo alloy steel was nitrocarburized and post-oxidized in salt bath and the 109 cycles fatigue tests were carried out. The results show that for the untreated specimens all the cracks initiate from the surface while for the treated specimens the cracks originate from the subsurface in short fatigue life regime and from internal inclusion in longer fatigue life regime. The treated specimens do not fracture in very high cycle fatigue regime and the fatigue limit increases by 51% after the treatment. No granular-bright-facet is observed in the vicinity of a non-metallic inclusion on the fracture surface. © 2011 Elsevier Ltd. All rights reserved.

Lv W.,Hefei University of Technology | Song W.-G.,Hefei University of Technology | Ma J.,Southwest Jiaotong University | Fang Z.-M.,CAS Shanghai Advanced Research Institute
IEEE Transactions on Intelligent Transportation Systems | Year: 2013

Modeling and simulation of pedestrian movement is a feasible and effective way to evaluate evacuation facilities and risk. Inspired by the visual field and movement characteristic of pedestrians, we developed a 2-D continuous model that integrates a self-slowing, local direction-changing mechanism, and visual hindrance information. The model allows for the movement in continuous space and time, only controlled by simple kinematic equations and visual hindrance distribution. In order to get the parameters of the kinematic equations, we conducted controlled experiments, collected empirical data, and obtained velocity-changing and direction-changing relations. We then validate the model by simulating three experimental scenarios, i.e., passage, bottleneck, and classroom evacuation. It is found that some typical phenomena such as the stop-and-go waves in the passage and lane formation in the bottleneck can be reproduced. The obtained fundamental diagram and specific flow agree with classic conclusions and experimental measures very well. It is hoped that the idea of this study may be helpful in promoting the modeling and simulation study of pedestrian flow. © 2000-2011 IEEE.

Zhang J.,Southwest Jiaotong University | Li T.,Southwest Jiaotong University | Ruan D.,Belgian Nuclear Research Center | Ruan D.,Ghent University | And 2 more authors.
Information Sciences | Year: 2012

Massive data mining and knowledge discovery present a tremendous challenge with the data volume growing at an unprecedented rate. Rough set theory has been successfully applied in data mining. The lower and upper approximations are basic concepts in rough set theory. The effective computation of approximations is vital for improving the performance of data mining or other related tasks. The recently introduced MapReduce technique has gained a lot of attention from the scientific community for its applicability in massive data analysis. This paper proposes a parallel method for computing rough set approximations. Consequently, algorithms corresponding to the parallel method based on the MapReduce technique are put forward to deal with the massive data. An extensive experimental evaluation on different large data sets shows that the proposed parallel method is effective for data mining. © 2012 Elsevier Inc. All rights reserved.

Huang Z.W.,Southwest Jiaotong University | Huang Z.W.,University of Birmingham
Intermetallics | Year: 2013

A γ-TiAl based fully lamellar alloy Ti-44Al-4Nb-4Hf-0.2Si-1B was isothermally forged and exposed at 700 °C for up to 10,000 h. It has been found that the combined addition of Nb and Hf rather than sole Nb has a positive effect on stabilisation of α2 lamellae. Compared to alloy Ti-44Al-8Nb-1B, less amount of α2 dissolved and less amount of β(B2 + ω) formed in alloy 4Nb-4Hf after the same forging and exposure scheme. As a result, the exposure-induced embrittlement is less severe in alloy 4Nb-4Hf. The ductility after 10,000-h exposure is reduced by 1/3, compared to the reduction by 2/3 in alloy 8Nb. The tensile strengths remain essentially unchanged while fatigue limit increased significantly for alloy 4Nb-4Hf. The mechanism behind the reduced α2 dissolution and β formation is discussed in relation to a changed partitioning behaviour and a slower diffusivity due to the combined addition of Nb and Hf. © 2013 Elsevier Ltd. All rights reserved.

Buhagiar J.,University of Birmingham | Qian L.,Southwest Jiaotong University | Dong H.,University of Birmingham
Surface and Coatings Technology | Year: 2010

Based on the success of the feasibility study reported, the surface properties of low-temperature plasma carburised P558 Ni-free medical grade (ASTM F2581) austenitic stainless steel have been fully evaluated in terms of electrochemical corrosion, dry- and corrosion-wear and fretting-wear in Ringer's solution. Anodic polarization tests demonstrated that the precipitate-free S-phase generated by low-temperature plasma carburising at 500 °C for 15 h can retain the good corrosion resistance of the untreated ASTM F2581 Ni-Free material in Ringer's solution. The wear resistance of the Ni-free austenitic stainless steel can be improved by 700% and 140% when reciprocating against a WC ball in air (dry-wear) and in Ringer's solution (corrosion-wear) respectively. In addition, the low-temperature plasma carburising treatment can considerably reduce the friction coefficient and improve the fretting-wear resistance of the Ni-free austenitic stainless steel in Ringer's solution. © 2010 Elsevier B.V.

Luo C.,Southwest Jiaotong University | Luo C.,Key Laboratory of Cloud Computing and Intelligent Technology | Li T.,Southwest Jiaotong University | Li T.,Key Laboratory of Cloud Computing and Intelligent Technology | And 2 more authors.
Information Sciences | Year: 2014

Set-valued information systems are important type of data tables and generalized models of single-valued information systems. Approximations are the focal point of approaches to knowledge discovery based on rough set theory, which can be used to extract and represent the hidden knowledge in the form of decision rules. Attribute generalization refers to dynamic change of the attribute set in an information system with respect to the requirements of real-life applications. In this paper, we focus on maintaining approximations dynamically in set-valued ordered decision systems under the attribute generalization. Firstly, a matrix-based approach for computing approximations of upward and downward unions of decision classes is constructed by introducing the dominant and dominated matrices with respect to the dominance relation. Then, incremental approaches for updating approximations are proposed, which involves several modifications to relevant matrices without having to retrain from the start on all accumulated training data. Finally, comparative experiments on data sets from UCI as well as synthetic data sets show the proposed incremental updating methods are efficient and effective for dynamic attribute generalization. © 2013 Elsevier Inc. All rights reserved.

Wen H.,Southwest Jiaotong University | Li S.,National Key Laboratory of Science and Technology on Reactor System Design Technology | Zhu X.,Southwest Jiaotong University | Zhou L.,National Key Laboratory of Science and Technology on Reactor System Design Technology
IEEE Network | Year: 2013

In this article we focus on the security in cognitive radio, which is one of the needs for new technologies requiring spectrum bands. The PHY-layer in CR is more complex than a conventional wireless communication system because of spectrum sensing and the dynamic spectrum access mechanism. Therefore, it becomes vulnerable to be invaded. We present the PHY-layer approaches to defense against security threats in CR networks. We analyze the validities and benefits of proposed approaches, which can be valid not only for the attacks in the PHY-layer but also for those in the upper layer. © 1986-2012 IEEE.

Chen H.,Southwest Jiaotong University | Chen H.,Key Laboratory of Cloud Computing and Intelligent Technology | Li T.,Southwest Jiaotong University | Li T.,Key Laboratory of Cloud Computing and Intelligent Technology | And 2 more authors.
Knowledge-Based Systems | Year: 2012

Approximations in rough sets theory are important operators to discover interesting patterns and dependencies in data mining. Both certain and uncertain rules are unraveled from different regions partitioned by approximations. In real-life applications, an information system may evolve with time by different factors such as attributes, objects, and attribute values. How to update approximations efficiently becomes vital in data mining related tasks. Dominance-based rough set approaches deal with the problem of ordinal classification with monotonicity constraints in multi-criteria decision analysis. Data missing frequently appears in the Incomplete Ordered Decision Systems (IODSs). Extended dominance characteristic relation-based rough set approaches process the IODS with two cases of missing data, i.e., "lost value" and "do not care". This paper focuses on dynamically updating approximations of upward and downward unions while attribute values coarsening or refining in the IODS. Under the extended dominance characteristic relation based rough sets, it presents the principles of dynamically updating approximations w.r.t. attribute values' coarsening and refining in the IODS and algorithms for incremental updating approximations of an upward union and downward union of classes. Comparative experiments from datasets of UCI and empirical results show the proposed method is efficient and effective in maintenance of approximations. © 2012 Elsevier Ltd. All rights reserved.

Huang Z.W.,Southwest Jiaotong University | Huang Z.W.,University of Birmingham | Cong T.,Southwest Jiaotong University
Intermetallics | Year: 2010

Both ingot-cast and forged Ti-44Al-8Nb-1B alloys were exposed at 700 °C in air for up to 10,000 h. The α2 lamellae in the two conditions are found to be thermodynamically unstable and readily decompose through phase transformations of α2 → γ, α2 → B2(ω) and α2 + γ → B2(ω). Widespread B2(ω) forms throughout the lamellar structure, resulting in a significant increase in volume fraction after 10,000-h exposure. This is attributed to the composition similarity between the transformed and parent phases. The partition coefficients for Ti/Al/Nb between B2(ω) and α2 and between B2(ω) and α2 + γ are all measured to be close to 1. The long-term exposure has induced embrittlement owing to oxygen releasing from α2 decomposition. Room-temperature ductility is only 1/5 and 1/3 of the original value for the two conditions, respectively. However, no clear decreasing trend in S-N fatigue strength is observed, suggesting that the embrittlement effect of B2(ω) on the surface crack initiation is difficult to detect. © 2009 Elsevier Ltd. All rights reserved.

Liu D.,Southwest Jiaotong University | Li T.,Southwest Jiaotong University | Ruan D.,Belgian Nuclear Research Center | Ruan D.,Ghent University | Zhang J.,Southwest Jiaotong University
Journal of Global Optimization | Year: 2011

As business information quickly varies with time, the extraction of knowledge from the related dynamically changing database is vital for business decision making. For an incremental learning optimization on knowledge discovery, a new incremental matrix describes the changes of the system. An optimization incremental algorithm induces interesting knowledge when the object set varies over time. Experimental results validate the feasibility of the incremental learning optimization. © 2010 Springer Science+Business Media, LLC.

Zhang J.,State Grid Corporation of China | He Z.Y.,Southwest Jiaotong University | Lin S.,Southwest Jiaotong University | Zhang Y.B.,State Grid Corporation of China | Qian Q.Q.,Southwest Jiaotong University
International Journal of Electrical Power and Energy Systems | Year: 2013

Fault classification is very important for power system operation because it is the premise of fault analysis process. In this paper, an ANFIS (Adaptive Neural Fuzzy Inference System) based fault classification scheme in neutral non-effectively grounded distribution system is proposed. The transient currents are obtained by wavelet transform after faults occur. According to the statistic characteristic of transient currents in different fault types, the fault identifiers are defined. The fault identifiers can characterize the traits of fault type and show different disciplinarian in different fault types. They are inputted into three ANFISs to obtain the fault type. The proposed approach only needs the voltages and currents measured at substation, and can identify ten types of short-circuit fault accurately. The simulation model is established in PSCAD/EMTDC environment, and the performance of the proposed approach is studied. The results show that it has high accuracy. Besides, the adaptability of proposed approach to the neutral compensated grounding system, different network configurations and so on are verified through simulation. Through simulation, the proposed approach exhibits good performance. © 2013 Elsevier Ltd. All rights reserved.

Zhao Y.,Southwest Jiaotong University | Fang X.,Southwest Jiaotong University | Huang R.,Olympus Communication Technology of America | Fang Y.,University of Florida
IEEE Transactions on Mobile Computing | Year: 2014

Multihop cellular networks (MCNs) have drawn tremendous attention due to its high throughput and extensive coverage. However, there are still three issues not well addressed. With the existence of relay stations (RSs), how to efficiently allocate frequency resource to relay links becomes a challenging design issue. For mobile stations (MSs) near the cell edge, cochannel interference (CCI) become severe, which significantly affects the network performance. Furthermore, the unbalanced user distribution will result in traffic congestion and inability to guarantee quality of service (QoS). To address these problems, we propose a quantitative study on adaptive resource allocation schemes by jointly considering interference coordination (IC) and load balancing (LB) in MCNs. In this paper, we focus on the downlink of OFDMA-based MCNs with time division duplex (TDD) mode, and analyze the characteristics of resource allocation according to IEEE 802.16j/m specification. We also design a novel frequency reuse scheme to mitigate interference and maintain high spectral efficiency, and provide practical LB-based handover mechanisms which can evenly distribute the traffic and guarantee users' QoS. Our study shows that our scheme not only meets the requirement on coverage, but also improves the throughput while accommodating more users in MCNs. © 2014 IEEE.

Yuan H.,Southwest Jiaotong University | Chini A.R.,University of Florida | Lu Y.,Tongji University | Lu Y.,University of Maryland College Park | Shen L.,Hong Kong Polytechnic University
Waste Management | Year: 2012

During the past few decades, construction and demolition (C&D) waste has received increasing attention from construction practitioners and researchers worldwide. A plethora of research regarding C&D waste management has been published in various academic journals. However, it has been determined that existing studies with respect to C&D waste reduction are mainly carried out from a static perspective, without considering the dynamic and interdependent nature of the whole waste reduction system. This might lead to misunderstanding about the actual effect of implementing any waste reduction strategies. Therefore, this research proposes a model that can serve as a decision support tool for projecting C&D waste reduction in line with the waste management situation of a given construction project, and more importantly, as a platform for simulating effects of various management strategies on C&D waste reduction. The research is conducted using system dynamics methodology, which is a systematic approach that deals with the complexity - interrelationships and dynamics - of any social, economic and managerial system. The dynamic model integrates major variables that affect C&D waste reduction. In this paper, seven causal loop diagrams that can deepen understanding about the feedback relationships underlying C&D waste reduction system are firstly presented. Then a stock-flow diagram is formulated by using software for system dynamics modeling. Finally, a case study is used to illustrate the validation and application of the proposed model. Results of the case study not only built confidence in the model so that it can be used for quantitative analysis, but also assessed and compared the effect of three designed policy scenarios on C&D waste reduction. One major contribution of this study is the development of a dynamic model for evaluating C&D waste reduction strategies under various scenarios, so that best management strategies could be identified before being implemented in practice. © 2011 Elsevier Ltd.

Pei Z.,Xihua University | Ruan D.,Belgian Nuclear Research Center | Ruan D.,Ghent University | Liu J.,University of Ulster | Xu Y.,Southwest Jiaotong University
Knowledge-Based Systems | Year: 2012

The paper treats and handles nuclear safeguard evaluations by using a linguistic aggregation approach. The overall evaluation is based on a hierarchical analysis of a state's nuclear activities on the basis of the IAEA physical model. In this framework, we analyse three kinds of weight information, i.e., belief degrees of linguistic evaluation values, weights of IAEA experts about indicators and strengths of indicators, where, different belief degrees of linguistic evaluation values correspond with different uncertain evaluations due to lack of complete information or conflict information. To aggregate these linguistic evaluation values, we propose a weighted linguistic aggregation operator, and discuss it's properties. Based on the weighted linguistic aggregation operator, we firstly use belief degrees of linguistic evaluation values and weights of IAEA experts to aggregate linguistic evaluation values of every indicator, then, we use strengths of indicators to aggregate linguistic evaluation values of indicators, and obtain linguistic evaluation value of every sub-factor, finally, we combine linguistic evaluation values of sub-factors to make the overall evaluation. Compared with existed approaches, we arrange linguistic evaluation values according to their belief degrees, and aggregated results of indicators are vectors of linguistic evaluation values in order of belief degree, this is different with cumulative belief degree of linguistic evaluation values, moreover, in the aggregation process, we analyse the aggregated results of "no information" and "conflict information". We compare our method with some existed methods for nuclear safeguard evaluations in an example, which supports and clarifies the method of this paper. © 2011 Elsevier B.V. All rights reserved.

Zhang J.,Southwest Jiaotong University | Li T.,Southwest Jiaotong University | Ruan D.,Belgian Nuclear Research Center | Ruan D.,Ghent University | Liu D.,Southwest Jiaotong University
International Journal of Intelligent Systems | Year: 2012

Approximations of a concept in rough set theory induce rules and need to update for dynamic data mining and related tasks. Most existing incremental methods based on the classical rough set model can only be used to deal with the categorical data. This paper presents a new dynamic method for incrementally updating approximations of a concept under neighborhood rough sets to deal with numerical data. A comparison of the proposed incremental method with a nonincremental method of dynamic maintenance of rough set approximations is conducted by an extensive experimental evaluation on different data sets from UCI. Experimental results show that the proposed method effectively updates approximations of a concept in practice. Copyright © 2012 Wiley Periodicals, Inc.

Zhang J.,Southwest Jiaotong University | Li T.,Southwest Jiaotong University | Ruan D.,Belgian Nuclear Research Center | Ruan D.,Ghent University | Liu D.,Southwest Jiaotong University
International Journal of Approximate Reasoning | Year: 2012

Set-valued information systems are generalized models of single-valued information systems. The attribute set in the set-valued information system may evolve over time when new information arrives. Approximations of a concept by rough set theory need updating for knowledge discovery or other related tasks. Based on a matrix representation of rough set approximations, a basic vector H(X) is induced from the relation matrix. Four cut matrices of H(X), denoted by H [μ,ν](X), H (μ,ν](X), H [μ,ν)(X) and H (μ,ν)(X), are derived for the approximations, positive, boundary and negative regions intuitively. The variation of the relation matrix is discussed while the system varies over time. The incremental approaches for updating the relation matrix are proposed to update rough set approximations. The algorithms corresponding to the incremental approaches are presented. Extensive experiments on different data sets from UCI and user-defined data sets show that the proposed incremental approaches effectively reduce the computational time in comparison with the non-incremental approach. © 2011 Elsevier Inc. All rights reserved.

Jayasinghe R.C.,Georgia State University | Perera A.G.U.,Georgia State University | Zhu H.,University of Georgia | Zhu H.,Southwest Jiaotong University | Zhao Y.,University of Georgia
Optics Letters | Year: 2012

coating material due to their low n profile. Therefore, it is necessary to better understand the optical properties of these nanorods. TiO2 nanorods grown on glass and Si substrates were characterized in the visible (0.4-0.8 μm) and infrared (2-12 μm) regions to extract their complex n profiles empirically. Application of these nanorods in multilayer AR coatings on infrared detectors is also discussed. Optimization of graded index profile of these AR coatings in the broad infrared region (2-12 μm) even at oblique angles of incidence is discussed. The effective coupling between the incoming light and multiple nanorod layers for reducing the reflection is obtained by optimizing the effect from Fabry-Perot oscillations. An optimized five-layer AR coating on GaN shows the reflectance less than 3.3% for normal incidence and 10.5% at 60° across the whole 2-8 μm spectral range. © 2012 Optical Society of America.

Yuan L.,Southwest Jiaotong University | Chao B.F.,Academia Sinica, Taiwan | Ding X.,Hong Kong Polytechnic University | Zhong P.,Southwest Jiaotong University
Journal of Geophysical Research: Solid Earth | Year: 2013

We investigate the 3-D tidal displacement field on Earth's surface recorded globally by 456 continuous global positioning system (GPS) stations of IGS spanning 1996-2011, for eight principal diurnal and semidiurnal tidal constituents. In-phase and quadrature amplitudes of the residual tidal displacements, after removal of an a priori body tide model, are estimated using the precise point positioning (PPP) technique on the daily GPS data; the resultant daily estimates are combined to derive final estimates for each tide at each station. The results are compared with the predictions of eight recent global ocean tide models, separately for coastal (307) and inland (149) stations. We show that GPS can provide tidal displacement estimates accurate to the level of 0.12 mm (horizontal) and 0.24 mm (vertical) for the lunar-only constituents (M2, N2, O1, and Q1) and less favorably for solar-related tidal constituents (S2, K2, K1, and P1), although improved by ambiguity resolution. Most recent ocean tide models fit the GPS estimates equally well on the global scale but do not agree well between them in certain coastal areas, especially for the vertical displacements, suggesting the existence of model uncertainties near shallow seas. The tidal residuals for the inland stations after removing both body tides and ocean tidal loading (OTL) furthermore show clear continental-scale spatial coherence, implying deficiencies of the a priori body tide modeling in catching lateral heterogeneity in elastic as well as inelastic properties in the Earth's deep interior. We assert that the GPS tidal displacement estimates now achieve sufficient accuracy to potentially provide constraints on the Earth's structure. © 2013. American Geophysical Union. All Rights Reserved.

Zhang J.,Southwest Jiaotong University | Zhang J.,Georgia State University | Wong J.-S.,Georgia State University | Li T.,Southwest Jiaotong University | Pan Y.,Georgia State University
International Journal of Approximate Reasoning | Year: 2014

Nowadays, with the volume of data growing at an unprecedented rate, large-scale data mining and knowledge discovery have become a new challenge. Rough set theory for knowledge acquisition has been successfully applied in data mining. The recently introduced MapReduce technique has received much attention from both scientific community and industry for its applicability in big data analysis. To mine knowledge from big data, we present parallel large-scale rough set based methods for knowledge acquisition using MapReduce in this paper. We implemented them on several representative MapReduce runtime systems: Hadoop, Phoenix and Twister. Performance comparisons on these runtime systems are reported in this paper. The experimental results show that (1) The computational time is mostly minimum on Twister while employing the same cores; (2) Hadoop has the best speedup for larger data sets; (3) Phoenix has the best speedup for smaller data sets. The excellent speedups also demonstrate that the proposed parallel methods can effectively process very large data on different runtime systems. Pitfalls and advantages of these runtime systems are also illustrated through our experiments, which are helpful for users to decide which runtime system should be used in their applications. © 2013 Elsevier Inc.

Cheng J.,Southwest Jiaotong University | Zhang G.,Southwest Jiaotong University | Neri F.,University of Jyväskylä | Neri F.,De Montfort University
Information Sciences | Year: 2013

Differential evolution (DE) is a prominent stochastic optimization technique for global optimization. After its original definition in 1995, DE frameworks have been widely researched by computer scientists and practitioners. It is acknowledged that structuring a population is an efficient way to enhance the algorithmic performance of the original, single population (panmictic) DE. However, only a limited amount of work focused on Distributed DE (DDE) due to the difficulty of designing an appropriate migration strategy. Since a proper migration strategy has a major impact on the performance, there is a large margin of improvement for the DDE performance. In this paper, an enhanced DDE algorithm is proposed for global numerical optimization. The proposed algorithm, namely DDE with Multicultural Migration (DDEM) makes use of two migration selection approaches to maintain a high diversity in the subpopulations, Target Individual Based Migration Selection (TIBMS) and Representative Individual Based Migration Selection (RIBMS), respectively. In addition, the diversity amongst the individuals is controlled by means of the proposed Affinity Based Replacement Strategy (ABRS) mechanism. Numerical experiments have been performed on 34 diverse test problems. The comparisons have been made against DDE algorithms using classical migration strategies and three popular DDE variants. Experimental results show that DDEM displays a better or equal performance with respect to its competitors in terms of the quality of solutions, convergence, and statistical tests. © 2013 Elsevier Inc. All rights reserved.

Ye G.,Chongqing University | Yuan H.,Southwest Jiaotong University | Shen L.,Hong Kong Polytechnic University | Wang H.,Chongqing Education College
Resources, Conservation and Recycling | Year: 2012

Construction waste management (CWM) can affect society from an economic perspective, a social perspective and an environmental perspective. It is found from existing literature that scant attention has been paid to take account of the dynamics nature of the CWM system and interactions among major variables in the system when evaluating its environmental performance. Therefore, in order to fill the research gap, we develop a model for evaluating the environmental performance of CWM by using a system dynamics approach; particular focus is given to the dynamic interrelations among major variables in the CWM system and how the dynamics interactions can influence the environmental performance of CWM. The application of the proposed model is demonstrated based on a real case from the construction industry of China. The simulation results not only provide valuable information on how to improve the environmental performance of CWM in the studied project, but also help build confidence in the dynamic model in general so that it can be adopted to simulate, evaluate, and subsequently improve the environmental performance of CWM in construction projects. © 2012 Elsevier B.V. All rights reserved.

Liang H.,Southwest Jiaotong University | Liang H.,University of Waterloo | Cai L.X.,Princeton University | Huang D.,Arizona State University | And 2 more authors.
IEEE Transactions on Vehicular Technology | Year: 2012

Mobile cloud computing is a promising technique that shifts the data and computing service modules from individual devices to a geographically distributed cloud service architecture. A general mobile cloud computing system is comprised of multiple cloud domains, and each domain manages a portion of the cloud system resources, such as the Central Processing Unit, memory and storage, etc. How to efficiently manage the cloud resources across multiple cloud domains is critical for providing continuous mobile cloud services. In this paper, we propose a service decision making system for interdomain service transfer to balance the computation loads among multiple cloud domains. Our system focuses on maximizing the rewards for both the cloud system and the users by minimizing the number of service rejections that degrade the user satisfaction level significantly. To this end, we formulate the service request decision making process as a semi-Markov decision process. The optimal service transfer decisions are obtained by jointly considering the system incomes and expenses. Extensive simulation results show that the proposed decision making system can significantly improve the system rewards and decrease service disruptions compared with the greedy approach. © 2012 IEEE.

Li Y.-L.,Southwest Jiaotong University | Li Y.-L.,Northeastern University China | Tang J.-F.,Northeastern University China | Chin K.-S.,City University of Hong Kong | And 2 more authors.
Information Sciences | Year: 2012

Quality function deployment (QFD) is a planning and problem-solving methodology used to translate customer requirements (CRs) into engineering characteristics (ECs) in the course of new product development (NPD). Estimating the correlation measures among ECs is a crucial step in the product planning house of quality (PPHOQ) construction process because these measures seriously affect the planning of development efforts. This study presents a rough set-based approach used to estimate the correlation measures by revealing the knowledge of a QFD team. The approach involves introducing the category factor of a correlation to express the influences of the correlation categories on the corresponding correlation measures. A case study of a two-cylinder washing machine is used to illustrate the proposed approach. The result shows that the novel approach is effective in revealing the related knowledge of the QFD team and facilitating NPD decision making. © 2011 Elsevier Inc. All rights reserved.

Yuan L.,Academia Sinica, Taiwan | Yuan L.,Southwest Jiaotong University | Chao B.F.,Academia Sinica, Taiwan
Earth and Planetary Science Letters | Year: 2012

We analyze the tidal displacement signals, for the eight major diurnal and semidiurnal tides, from Global Positioning System (GPS) measurements made at the Western United States over the past 16. years with 1075 independent stations. By careful examinations among inland versus coastal GPS data we are able to demonstrate that estimated precisions down to the level of ~0.1. mm (horizontal) and ~0.3. mm (vertical) have been reached for the tidal signals, and that at such precisions coherent spatial patterns are revealed in the residual tidal amplitudes and phases after the removal of a priori modeled effects of body tides and ocean tidal loading (OTL). We demonstrate the facility of modern precise GPS data in not only constraining the ocean tide models but, more significantly, in providing source data in terms of regional, complex Love numbers for geophysical inference of the heterogeneities of elastic and inelastic structures in the solid Earth's deep interior on tidal timescales. © 2012.

Zhang Y.,Xijing University | Zhang Y.,Southwest Jiaotong University
Journal of Modern Transportation | Year: 2012

The aerodynamic drag on a train running in an evacuated tube varies with tube air pressure, train speed and shape, as well as blockage ratio. This paper uses numerical simulations to study the effects of different factors on the aerodynamic drag of a train running at subsonic speed in an evacuated tube. Firstly, we present the assumption of a steady state, two dimensional, incompressible viscous flow with lubricity wall conditions. Subsequently, based on the Navier-Stokes equation and the k-ε turbulent models, we calculate the aerodynamic drag imposed on the column train with a 3-meter diameter running under different pressure and blockage ratio conditions in an evacuated tube transportation (ETT) system. The simulation is performed with FLUENT 6.3 software package. An analyses of the simulation results suggest that the blockage ratio for ETT should be in the range of 0.25-0.7, and the tube internal diameter in the range of 2-4 m, with the feasible vacuum pressure in the range of 1-10000 Pa for the future subsonic ETT trains. © 2012 JMT. All rights reserved.

Zhang J.,Southwest Jiaotong University | Zhang J.,Georgia State University | Li T.,Southwest Jiaotong University | Chen H.,Southwest Jiaotong University
Information Sciences | Year: 2014

As a soft computing tool, rough set theory has become a popular mathematical framework for pattern recognition, data mining and knowledge discovery. It can only deal with attributes of a specific type in the information system by using a specific binary relation. However, there may be attributes of multiple different types in information systems in real-life applications. Such information systems are called as composite information systems in this paper. A composite relation is proposed to process attributes of multiple different types simultaneously in composite information systems. Then, an extended rough set model, called as composite rough sets, is presented. We also redefine lower and upper approximations, positive, boundary and negative regions in composite rough sets. Through introducing the concepts of the relation matrix, the decision matrix and the basic matrix, we propose matrix-based methods for computing the approximations, positive, boundary and negative regions in composite information systems, which is crucial for feature selection and knowledge discovery. Moreover, combined with the incremental learning technique, a novel matrix-based method for fast updating approximations is proposed in dynamic composite information systems. Extensive experiments on different data sets from UCI and user-defined data sets show that the proposed incremental method can process large data sets efficiently. © 2013 Elsevier Inc. All rights reserved.

Ouattara M.,Georgia State University | Bentley Cunha E.,Georgia State University | Li X.,Southwest Jiaotong University | Huang Y.-S.,Georgia State University | And 2 more authors.
Molecular Microbiology | Year: 2010

A growing body of evidence suggests that surface or secreted proteins with NEAr Transporter (NEAT) domains play a central role in haem acquisition and trafficking across the cell envelope of Gram-positive bacteria. Group A streptococcus (GAS), a β-haemolytic human pathogen, expresses a NEAT protein, Shr, which binds several haemoproteins and extracellular matrix (ECM) components. Shr is a complex, membrane-anchored protein, with a unique N-terminal domain (NTD) and two NEAT domains separated by a central leucine-rich repeat region. In this study we have carried out an analysis of the functional domains in Shr. We show that Shr obtains haem in solution and furthermore reduces the haem iron; this is the first report of haem reduction by a NEAT protein. More specifically, we demonstrate that both of the constituent NEAT domains of Shr are responsible for binding haem, although they are missing a critical tyrosine residue found in the ligand-binding pocket of other haem-binding NEAT domains. Further investigations show that a previously undescribed region within the Shr NTD interacts with methaemoglobin. Shr NEAT domains, however, do not contribute significantly to the binding of methaemoglobin but mediate binding to the ECM components fibronectin and laminin. A protein fragment containing the NTD plus the first NEAT domain was found to be sufficient to sequester haem directly from methaemoglobin. Correlating these in vitro findings to in vivo biological function, mutants analysis establishes the role of Shr in GAS growth with methaemoglobin as a sole source of iron, and indicates that at least one NEAT domain is necessary for the utilization of methaemoglobin. We suggest that Shr is the prototype of a new group of NEAT composite proteins involved in haem uptake found in pyogenic streptococci and Clostridium novyi. © 2010 Blackwell Publishing Ltd.

Li X.-Y.,Southwest Jiaotong University | Wu F.,Southwest Jiaotong University | Wu Y.-F.,China Railway Siyuan Survey and Design Group CO. | Chen W.-Q.,Zhejiang University
Mechanics of Materials | Year: 2014

This paper is concerned with contact problem for a half-space of two-dimensional hexagonal quasi-crystal punched by three common indenters (cylindrical flat-ended, conical and spherical punches). Based on the Green's functions for the half-space subjected to an external phonon source exerted on the surface, the superposition principle is applied to constructing the boundary integral equation. Relations between the indentation force and the penetration depth, and the indentation stiffness constants are explicitly obtained for these three indenters. Complete and exact fields in the half-space are given in terms of elementary functions. The present theoretical solutions can not only serve as benchmark for computational contact mechanics, but also apply to guiding future indentation experiments. © 2014 Elsevier Ltd. All rights reserved.

Tang X.,Southwest Jiaotong University | Gong G.,University of Waterloo
IEEE Transactions on Information Theory | Year: 2010

In this paper, we give three new constructions of binary sequences of period 4N with optimal autocorrelation value or optimal autocorrelation magnitude using N ×4 interleaved sequences. Yu and Gong recently found any binary sequence of period 4N with optimal autocorrelation value constructed from an almost difference set by Arasu is an N ×4 interleaved sequence for which all four columns in its N ×4 array are shift equivalent up to the complement. We found that it is not necessary that four columns are shift equivalent. Instead, it could be a pair of related sequences together with their shifts as the column sequences. The first construction is to use a generalized GMW sequence of period N=22k-1 and its modified version, the second construction is to use a twin prime sequence of length N=p(p+2) and its modified version, and the third construction, a pair of Legendre sequences of period N=p (p odd prime) with their respective first terms complementary (the 2-level autocorrelation property is not needed for the Legendre sequence). The comparison with the known constructions are given. For the new sequences with optimal autocorrelation value, their corresponding new almost difference sets are also derived. © 2006 IEEE.

Zhang N.,Nanjing University of Technology | Fu C.C.,University of Maryland University College | Che H.,Southwest Jiaotong University
Engineering Structures | Year: 2011

Curved prestressed concrete structures with unbonded tendons are widely used in highway interchanges and industrial cooling towers, etc. In engineering practice, there is a demand to establish calculating methods for analyzing and designing these prestressed concrete curved structures with unbonded tendons. However, there are some difficulties in calculating the ultimate strength of these curved structures. The major difficulty is to calculate the ultimate stress in unbonded tendons. The assumption of a plane cross-section cannot be adopted here because of the slip between unbonded tendon and concrete. Thus, many formulas for calculating the ultimate stress in unbonded tendons were mainly based on experimental data fitting. In order to obtain the ultimate stress in unbonded tendons from mechanical principles, instead of using experimental data fitting formula, an advanced nonlinear analysis method to calculate ultimate stress in unbonded tendons is developed. The analysis model is established by using the Reissner-Mindlin medium thickness plate theory allowing for the influence of the transverse shear deformation. The orthotropic increment constitutive model of concrete is extended to solve the medium thickness plate problem. The tension stiffening of the cracked concrete is considered in the nonlinear analysis model. The numerical formulation of calculating the stress increment in an unbonded tendon is established by using the spatial displacement relationship. Instead of using general-purpose programs such as ANSYS and ABAQUS, a computer program specifically for predicting the nonlinear response of a prestressed concrete curved slab structure with unbonded tendons and calculating the ultimate stress in unbonded tendons is developed by authors. Six test models of prestressed concrete curved slabs with unbonded tendons are reported. The calculated results using this program are compared with test results, where their relative deviation is less than 3.0%, which validates the proposed method. These study results can be used for analysis, especially to design the strength of prestressed concrete curved structures with unbonded tendons. And, this research work also proposes a new approach, which can be customized to fit into general purposed FEM programs, such as APDL (ANSYS Parametric Design Language), for analyzing the nonlinear structural behavior of these curved structures. © 2010 Elsevier Ltd.

Shimatani Y.,University of Toyama | Shiozawa K.,University of Toyama | Nakada T.,Yamaha | Yoshimoto T.,Kanazawa Institute of Technology | Lu L.,Southwest Jiaotong University
International Journal of Fatigue | Year: 2011

To investigate the fatigue properties of matrix high-speed tool steel (0.7C-0.1W-3Mo-2V) under very high cycle fatigue regimes, cantilever-type rotating bending fatigue tests were carried out on hour-glass shaped specimens in an air atmosphere at room temperature. The specimen surfaces were finished by grinding and cutting processes which give different surface compressive residual stresses. Both specimen treatments showed a clear duplex S-N curve, composed of three types of failure mode depending on the stress amplitude. A map of the appearance of failure modes relating stress amplitude to residual stress was proposed. The dependence of the S-N curve on a critical size of inclusion at the crack origin was demonstrated by the estimation of crack growth rate from the S-N data. © 2010 Elsevier Ltd. All rights reserved.

Liu Z.,Southwest Jiaotong University | Zhang Q.,Southwest Jiaotong University
IEEE Transactions on Instrumentation and Measurement | Year: 2014

Spectral kurtosis (SK) is a statistical tool, which can indicate both non-Gaussian components in a signal and their locations in the frequency domain. The computation methods of SK decide the characteristics of transient disturbances. We propose a new computation method based on Choi-Williams distribution to recognize the transient disturbances. Through the comparisons and analysis of different computation methods for five transient disturbances, the proposed method can better reflect their characteristics difference. In addition, the relationships between SK and transient disturbance parameters (amplitude, phase, duration, noise, and so on) are analyzed and discussed in detail, and a recognition plan is proposed. We, respectively, adopted the simulation signals with random disturbance parameters and different noise, power systems computer aided design, and real-life signals to prove the recognition performance. The experimental results show that the method is feasible and simple, and the recognition rate of five transient disturbances is high and satisfied. Especially, the transient impulsive and oscillation with noise can be completely recognized using the proposed method in this paper. © 1963-2012 IEEE.

Chen F.,Southwest Jiaotong University | He H.-J.,Southwest Jiaotong University | Wang H.-X.,Southwest Jiaotong University
Jisuanji Xuebao/Chinese Journal of Computers | Year: 2012

This paper proposes an image self-recovery fragile watermarking scheme with variable watermark embedding capacity. Both watermark embedding payload and security are taken into account. For each block of size 2×2 pixels, the features are extracted to generate the recovery watermark with different length-6 bits for a plain block and 12 bits for a texture block. The recovery watermark of an image block is inserted into the less significant bit planes of the other block based on the secret key. The validity of a block is determined by comparing the features computed by the block content with the ones reconstructed by the corresponding recovery watermark incorporating with its neighbor characteristic. The variable-capacity recovery watermark contains the adequate information of image block to as few bits as possible. The recovery watermark is inserted in the original image only once, and used to both tamper detection and tamper recovery in the proposed scheme. These strategies make the watermark embedded payload as low as possible and the ability against the constant-average attack to be improved. Experimental results show that the proposed scheme not only has the better quality of the watermarked and recovered images, but also resists the known counterfeiting attack such as the collage attack and the constant-average attack.

Chen X.,Southwest Jiaotong University | Chen X.,University of Sichuan | Yu J.,National Engineering Research Center for Compounding and Modification of Polymer Materials | Zhang Z.,Southwest Jiaotong University | Lu C.,University of Sichuan
Carbohydrate Polymers | Year: 2011

Cellulose fibers were extracted from the rice straw by a mechanical-high pressure steam technique. The structure, chemical composition and thermal properties of cellulose fibers were investigated by using Fourier transform infrared (FTIR) spectroscopy, wide-angle X-ray diffraction (WAXD), scanning electron microscopy (SEM), and thermogravimetric analysis (TGA). FTIR analysis and chemical composition of fibers demonstrate that this mechanical-high pressure steam treatment can result in partial removal of hemicellulose and lignin from the structure of fibers. WAXD results reveal that this results in improved crystallinity of the fibers. The rice straw fibers are determined to have diameters in the range of 5-10 μm. After mechanical-high pressure steam treatments, the thermal properties of the rice straw fibers from the TGA results are found to increase dramatically after treatments. The degradation temperature of the rice straw fibers reaches over 280 °C, which is reasonably promising for the use of these fibers in reinforced-polymer composites. © 2011 Elsevier Ltd. All rights reserved.

Li P.,Southwest Jiaotong University | Yang Y.,Southwest Jiaotong University | Chen G.,Southwest Jiaotong University
Nonlinear Dynamics | Year: 2015

The nonlinear flutter oscillations of a restrained cantilevered plate induced by subsonic flow have been investigated in this paper. A non-smooth piecewise linear spring is considered to simulate the motion constraints. A set of discrete equations is obtained by the Galerkin method. Emphasis is placed on the limit cycle oscillations (LCOs) of the aeroelastic system due to the nonlinearity. A flutter determinant is developed to the analysis of flutter instability. The system loses stability by flutter and undergoes LCOs afterward due to the nonlinearity. The stability of LCOs is addressed on the basis of the equivalent linearized method. The location of the nonlinear motion constraints is intimately bound up with the type of Hopf bifurcations (subcritical or supercritical). Interestingly, for some special cases, the Hopf bifurcations are both subcritical and supercritical. The two-multiple semi-stable limit cycle bifurcation due to the extreme point of the flutter curve is also determined. The analytical results predicted by the analysis scheme are sufficiently validated by numerical calculations. © 2014, Springer Science+Business Media Dordrecht.

Ma N.,Southwest Jiaotong University | Li C.-H.,Southwest Jiaotong University
Gongcheng Lixue/Engineering Mechanics | Year: 2010

As a new type of track, Ladder Sleeper is developed based on the theory of Longitudinal sleeper. It overcomes the shortage of the traditional Lateral sleeper in many aspects, but some of its important features remain unaddressed. The existing research mostly focuses on the static behaviors. With the development of the high-speed train, the dynamic problems of railway are becoming more and more prominent. In order to understand the dynamic characteristics of Ladder Sleeper fully and to lay the foundation for the analysis of Ladder Sleeper Track, this paper investigates the vertical vibration modal to get the natural frequency and vibration mode. The results show that Ladder Sleeper has the characteristic of integrity and transitivity.

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

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

Li T.,Southwest Jiaotong University | Zhang J.,Southwest Jiaotong University | Zhang W.,Southwest Jiaotong University
Journal of Modern Transportation | Year: 2011

Based on the train-track coupling dynamics and high-speed train aerodynamics, this paper deals with an improved algorithm for fluid-structure interaction of high-speed trains. In the algorithm, the data communication between fluid solver and structure solver is avoided by inserting the program of train-track coupling dynamics into fluid dynamics program, and the relaxation factor concerning the load boundary of the fluid-structure interface is introduced to improve the fluctuation and convergence of aerodynamic forces. With this method, the fluid-structure dynamics of a highspeed train are simulated under the condition that the velocity of crosswind is 13.8 m/s and the train speed is 350 km/h. When the relaxation factor equals 0.5, the fluctuation of aerodynamic forces is lower and its convergence is faster than in other cases. The side force and lateral displacement of the head train are compared between off-line simulation and co-simulation. Simulation results show that the fluid-structure interaction has a significant influence on the aerodynamics and attitude of the head train under crosswind conditions. In addition, the security indexes of the head train worsen after the fluid-structure interaction calculation. Therefore, the fluid-structure interaction calculation is necessary for high-speed trains. © 2011 JMT. All rights reserved.

Tu Y.,Southwest Jiaotong University | Fan P.,Southwest Jiaotong University | Hao L.,Southwest Jiaotong University | Tang X.,Southwest Jiaotong University
IEEE Signal Processing Letters | Year: 2010

In this letter, we introduce a simple approach to generate Z-periodic complementary set (ZPCS) by performing phase shift operation on periodic complementary sequence set (PCS). Favorable correlation properties of ZPCS enable its applications not only in MIMO channel estimation as optimal training sequences, but also in MC-CDMA system as spreading sequences to efficiently handle multipath interference (MI) and multiple access interference (MAI). Our approach provides flexible choices for zero correlation zone (ZCZ) length and set size. The resultant ZPCS is optimal with respect to the theoretical bound. © 2006 IEEE.

Xiao Y.,Southwest Jiaotong University | Gong T.,Southwest Jiaotong University | Zhou S.,Southwest Jiaotong University
Biomaterials | Year: 2010

A simple and effective approach was introduced to functionalize multi-walled carbon nanotubes (MWNTs) by in situ deposition of hydroxyapatite (HA) to improve their hydrophilicity and biocompatibility. Firstly, we prepared two types of pre-functionalized MWNTs: acid-oxidated MWNTs and covalently modified MWNTs by poly (ethylene glycol) (PEG). The influences of the acid-oxidated time, pre-phosphorylation, and PEGylation of MWNTs on in situ growth of HA were further investigated in simulated body fluid (SBF) with ionic concentration: 2, 5 and 10 times, respectively, at 37 °C for 24. h. The results exhibited that all these factors have positive effects on the HA crystals growth, especially the PEGylation of MWNTs plays a key role during the deposition. Finally, the methyl thiazolyl tetrazolium (MTT) assay was performed to evaluate their cytotoxicity, which showed that the PEGylated MWNTs wrapped by HA crystals have the best biocompatibility. © 2010 Elsevier Ltd.

Chigira M.,Kyoto University | Wu X.,Southwest Jiaotong University | Inokuchi T.,Japan National Research Institute for Earth Science and Disaster Prevention | Wang G.,Kyoto University
Geomorphology | Year: 2010

The 2008 Wenchuan earthquake with a magnitude of Mw 7.9 induced numerous slope movements on the hanging walls of fault surface ruptures and on steep inner valleys along the Minjiang River. Landslide moving directions showed preferred orientations normal to the fault ruptures, indicating the effect of the directivity of the seismic wave. The most common landslides were of carbonate rocks, which are easily dissolved and decrease the contact surfaces. The largest non-volcanic landslide in history was induced in bedded dolomite by the earthquake, and was preceded by gravitational deformation with ridge-top depressions. Valley-fill materials were mobilized at 36 locations, probably by pore water pressure build up. © 2010 Elsevier B.V.

Shi Z.,Southwest Jiaotong University | Zhao R.,Southwest Jiaotong University
Yingyong Lixue Xuebao/Chinese Journal of Applied Mechanics | Year: 2012

According to the engineering characteristic of bridge structure, boundary condition variation and structure damages as well as the parameterization of them are analyzed in detail. The optimization inversion question is established with target function of minimum sum of square errors between mode parameters tested and calculated by using constrained optimization theory. The first and second order eigenvalues and eigenvectors of the corresponding dynamic equation are introduced into the optimization inversion question based on matrix perturbation theory, so the question is simplified as optimization inversion of the nonlinear least square. According to the fact that boundary condition of bridge structure has much more effect on mode parameters, pre-identification of boundary condition is used. Then the detailed method and process of bridge structure damage detection are put forward accounting for the boundary condition, in which pre-location method of element mode strain energy is adopted. At last, the numerical analysis results of a maglev railway girder show that the damage detection method can effectively detect change of boundary condition and structure damages with fairly well precision and the maximum relative detection error is 12.48%.

Guo J.,Southwest Jiaotong University | Zhang Y.,Southwest Jiaotong University
Beijing Jiaotong Daxue Xuebao/Journal of Beijing Jiaotong University | Year: 2012

The paper introduced the achievement of Chinese high-speed railway signal system, and then analyzed the technical characteristics of China Train Control System(CTCS). After summarizing the development of CTCS, some problems of the technical standard and configuration on CTCS were mentioned, and the modification suggestions were put forward to decrease the risk on CTCS.

Zhang Q.,Southwest Jiaotong University | Li Q.,Southwest Jiaotong University
Tumu Gongcheng Xuebao/China Civil Engineering Journal | Year: 2012

Because of the complexity of the structural system and the mechanical features of cable-girder anchorage, systematic study is necessary for structural design. Take the Sutong Bridge's cable-girder anchorage structure as a subject of investigation, the load transfer path and mechanism and corresponding key influencing factors were systematically studied through theoretical analysis and model test. The results indicate that the load transfer function of anchorage is accomplished by the combination of shear and bending of its key plates, and the differences of stress distribution in such plates are induced by the load transfer characteristics mentioned above. Depending on the complexity of anchorage's structural system, notable difference of mechanical characteristics can be induced by the combinations of structural design parameters. The lengths of anchorage's bottom and top plates are key parameters that dominate the cable-girder anchorage's load transfer mechanism. The effects of different factors are interactive, and the rational design parameters should be determined by comprehensive study.

Zhao T.,Southwest Jiaotong University | Xiao J.,Southwest Jiaotong University
Kongzhi Lilun Yu Yingyong/Control Theory and Applications | Year: 2012

Type-2 fuzzy sets and intuitionistic fuzzy sets have a wide range of practical applications. Type-2 fuzzy sets enhance the ability of the system for dealing with uncertainties. Intuitionistic fuzzy sets provide a theoretical basis to manage the hesitation information appearing to people in judging questions. In this paper, we introduce the concept of type-2 intuitionistic fuzzy sets under type-2 fuzzy sets and intuitionistic fuzzy sets. Furthermore, we prove that type-2 intuitionistic fuzzy sets are the generalized forms of type-1 fuzzy sets, intuitionistic fuzzy sets, interval-valued fuzzy sets and interval-valued intuitionistic fuzzy sets. The basic operations of type-2 intuitionistic fuzzy sets and type-2 intuitionistic fuzzy relations are discussed. Finally, the approximation reasoning based on the type-2 intuitionistic fuzzy theory is studied. A practical example illustrates the practical application background of type-2 intuitionistic fuzzy sets.

Yang Q.,Southwest Jiaotong University | Lin J.,Southwest Jiaotong University
2011 2nd International Conference on Mechanic Automation and Control Engineering, MACE 2011 - Proceedings | Year: 2011

Track irregularities can cause deterioation of riding comfort and derailment.Track gauge variation is one of the basic track irregularities.Track Recording Car is an automated track inspection vehicle on a rail transport system used to test several geometric parameters of the track .Track geomeotry parameters generally measured include position,speed,gauge,alig nment,crosslevel,curvature and so on .This paper presents a novel technique for the measurement of track gauge variation ,a new measurement system was introduced and been in assembled on a new type underground track recoring car. © 2011 IEEE.

Gao J.-M.,Southwest Jiaotong University | Zhai W.-M.,Southwest Jiaotong University | Wang K.-Y.,Southwest Jiaotong University
Tiedao Xuebao/Journal of the China Railway Society | Year: 2012

By means of the vehicle-track coupled dynamics theory and the corresponding simulation software TTISIM, the effect of track irregularity wavelength on the dynamic response of the vehicle system was investigated. The sensitive wavelength of track irregularity in high-speed operation was discussed. The analysis results show that the dynamic responses of the vehicle system are larger under the condition that the track irregularity wavelength varies in a certain range when the running speed is 250km/h to 400km/h. The wavelength ranges of track irregularities corresponding to the larger responses of vehicle system vary with different irregularity type or running speed. It is found that the vehicle system dynamic responses are sensitive to track vertical profile irregularity, track alignment irregularity and track cross-level irregularity when their wavelength ranges are 80~160 m, 40~120 m and 50~160 m at the speed of 250 km/h to 400 km/h. The sensitive wavelength range of track twist irregularity is 40~100 m under the above mentioned speed conditions.

Song X.,Southwest Jiaotong University | Zhai W.,Southwest Jiaotong University
Zhongguo Tiedao Kexue/China Railway Science | Year: 2012

The dynamic finite element model of the infrastructure above embankment was established for CRTS II slab ballastless track via ANSYS to analyze the dynamic stress distribution and transfer law of track and subgrade under the moving load with different speeds. Results indicate that, in different layers of track and subgrade, the dynamic stress distribution along the lateral direction has little to do with the speed of the moving load but has much to do with the distance away from the bottom of the rail. The stress distribution of track slab along the lateral direction presents to be a hump, and the stress reaches its maximum value right beneath the rail. The stress level between the rails is basically identical. With the increase of the depth, the dynamic stress of subgrade attenuates sharply when the depth is less than 1 m away from rail bottom, attenuates almost linearly within 1~4 m and attenuates slowly beyond 4 m. It is also found that the dynamic stress of infrastructure at different position increases on the whole with the increase of moving load speed. The stress increases linearly with the increase of speed in the range of train speed from 80 to 350 km·h -1. Whereas when the speed is less than 80 km·h -1 or greater than 350 km·h -1, the stress does not change obviously.

Zhang Q.,Southwest Jiaotong University | Li Q.,Southwest Jiaotong University
Tumu Gongcheng Xuebao/China Civil Engineering Journal | Year: 2012

For long-span cable-stayed bridges with steel box girders, the load transfer between cables and girders is accomplished by cable-girder anchorage. With the complex load transfer mechanism and stress concentration induced by large load, rational design of cable-girder anchorage is critical to long-span cable-stayed bridges. The cable-girder anchorage of the Sutong Bridge was investigated, and the mechanism of cable-girder anchorage was studied by using theoretical model and model test. The study indicated that the results of theoretical model were in accordance with that of model test, and the availability of theoretical model was demonstrated. The load transfer mechanisms of the main components of cable-girder anchorage are markedly different from each other. The stress concentration in web plate, top and bottom plate is predominant.

Zhao H.,Southwest Jiaotong University | Qin K.,Southwest Jiaotong University
Knowledge-Based Systems | Year: 2014

Feature selection in incomplete decision table has gained considerable attention in recently. However many feature selection methods are mainly designed for incomplete data with categorical features. In this paper, we introduce an extended rough set model, which is based on neighborhood-tolerance relation and is applicable to incomplete data with mixed categorical and numerical features. Neighborhood-tolerance conditional entropy is proposed from this model, which is an uncertainty measure and can be used to evaluate feature subset. It is known that dependency is an important feature evaluation measure based on rough set theory. The comparison and analysis of classification complexity are made between the two measures and it is indicated that neighborhood-tolerance conditional entropy is a more effective feature evaluation criterion than dependency in incomplete decision table. Then the heuristic feature selection algorithm based on neighborhood-tolerance conditional entropy is constructed. Experimental results show that our proposal is applicable and effective to incomplete mixed data. © 2013 Elsevier B.V. All rights reserved.

Yue Y.,Southwest Jiaotong University | Xie J.,Southwest Jiaotong University
International Journal of Non-Linear Mechanics | Year: 2013

A three-degree-of-freedom vibro-impact system with symmetric two-sided rigid constraints is considered. Since the symmetric period n-2 motion of the vibro-impact system corresponds to the symmetric fixed point of the Poincaré map of the vibro-impact system, we investigate bifurcations of the symmetric period n-2 motion by researching into bifurcations of the associated symmetric fixed point. The Poincaré map of the system has symmetry property, and can be expressed as the second iteration of another unsymmetric implicit map. Based on both the Poincaré map and the unsymmetric implicit map, the center manifold technique and the theory of normal forms are applied to deduce the normal form of the Neimark-Sacker-pitchfork bifurcation of the symmetric fixed point. By numerical analysis, we obtain the Neimark-Sacker-pitchfork bifurcation of the symmetric fixed point of the Poincaré map in the vibro-impact system. © 2012 Elsevier Ltd.

Dou X.,Southwest Jiaotong University
Energy Policy | Year: 2013

For a developing country such as China, it is important to select a fair pattern that is suitable for China's national conditions for low carbon-economy development, as it has a direct impact on the success (or not) of low carbon-economy development. This research shows that, under the real-life conditions of China's development, different development patterns should be practised depending on specific socioeconomic conditions. Among them, one of the most critical issues is how to make full use of natural forces, and thus the nature-oriented development pattern should be practised in full. At the same time, China should still practise either the single regional differential or the multi-regional linkage development pattern under different conditions and either the imposed or the induced development pattern at the different stages of development. © 2013 Elsevier Ltd.

Zia-Ur Rehman M.,Southwest Jiaotong University | Li T.,Southwest Jiaotong University | Yang Y.,Southwest Jiaotong University | Wang H.,Southwest Jiaotong University
Knowledge-Based Systems | Year: 2014

Data mining has become a key ingredient in establishing intelligent decision support systems. As one of main branches in data mining, data stream clustering has received much attention over the past decade. Most existing data stream clustering techniques count on Euclidean distance metric for finding similar objects and hence produce spherical clusters which are not always suitable to represent the data. Moreover, in most of the real world problems, we come across the data of varying density which cannot be handled by density-based clustering techniques. In this paper, we introduce a new clustering technique called Hyper-Ellipsoidal Clustering for Evolving data Stream (HECES) based on the recently proposed HyCARCE algorithm. In HECES, a few modifications in the HyCARCE algorithm are made for handling stream clustering problem: sliding window model is used to handle incoming stream of data to minimize the impact of the obsolete information on recent clustering results; shrinkage technique is used to avoid the singularity issue in finding the covariance of correlated data; a novel technique for merging the initial ellipsoids is used to obtain the final clusters instead of a computationally intensive process of expansion and adjustment. HECES relies on Mahalanobis distance metric to cluster the data points and hence results in ellipsoidal shaped clusters. It can successfully handle data of varying density. Experiments on various synthetic and real datasets for clustering streaming data provide a comparative validation of our approach. © 2014 Elsevier Ltd. All rights reserved.

Li X.-Y.,Southwest Jiaotong University
Proceedings of the Royal Society A: Mathematical, Physical and Engineering Sciences | Year: 2013

This paper presents fundamental solutions for an infinite space of one-dimensional hexagonal quasicrystal medium, which contains a penny-shaped or half-infinite plane crack subjected to two identical thermal loadings on the upper and lower crack lips. In view of the symmetry of the problem with respect to the crack plane, the original problem is transformed to a mixed boundary problem for a half-space, which is solved by means of a generalized method of potential theory conjugated with the newly proposed general solutions. When the cracks are under the action of a pair of point temperature loadings, fundamental solutions in terms of elementary functions are derived in an exact and complete way. Important parameters in crack analyses such as stress intensity factors and crack surface displacements are presented as well. The underlying relations between the fundamental solutions for the two cracks involved in this paper are discovered. The temperature fields associated with these two cracks are retrieved in alternative manners. The obtained solutions are of significance to boundary element analysis, and have an important role in clarifying simplified studies and serving as benchmarks for computational fracture mechanics can be expected to play. Copyright © The Royal Society 2013.

Li N.,Southwest Jiaotong University | Helleseth T.,University of Bergen | Tang X.,Southwest Jiaotong University
Finite Fields and their Applications | Year: 2013

A class of permutation polynomials with given form over finite fields is investigated in this paper, which is a further study on a recent work of Zha and Hu. Based on some particular techniques over finite fields, two results obtained by Zha and Hu are improved and new permutation polynomials are also obtained. © 2013 Elsevier Inc.

Lu X.,University of Sichuan | Cui S.,Southwest Jiaotong University
Bioresource Technology | Year: 2010

In this paper, we explored a facile method to prepare stable silver nanoparticles (Ag NPs) using extracted wool keratin as the capping agent. The formation of Ag NPs was investigated by UV-Vis spectroscopy, X-ray photo-electron spectrometer and X-ray diffraction spectrometer. The morphology of the NPs was detected by scanning electron microscopy in vacuum and atomic force microscopy in fluid. The possible interactions between the silver core and the capping agent have been investigated using Fourier transform infrared spectroscopy. The effects of keratin concentration on the incubation of the NPs were studied by UV-Vis spectra. It was found that under alkaline condition the process of incubation was much faster than that under neutral pH condition. The photoluminescence properties of the Ag NPs were also investigated. We believe that this work is helpful for the high-value utilization of wool and other keratin-rich bioresource. © 2010 Elsevier Ltd. All rights reserved.

Liu J.,University of Ulster | Liu J.,Southwest Jiaotong University | Li W.,University of Electronic Science and Technology of China | Chen S.,University of Ulster | Xu Y.,Southwest Jiaotong University
Information Sciences | Year: 2014

It is commonsense that people do express, think, reason, and make decision directly using linguistic terms in natural language rather than using numerical quantification. How to establish the formalized approach imitating the common way of human being's to manipulate directly linguistic terms without numerical approximation to provide the rational decision is still an open research area. Investigations on the algebraic structure of linguistic term set for varied decision making applications (especially in social science) still lack a formalism for development of strict linguistic valued logic system as a theoretical foundation and its approximate reasoning scheme in practice. To attain this goal we characterize and construct a typical structure of commonly used linguistic term sets in natural language by a lattice-ordered algebra structure - lattice implication algebra (LIA), where ?ukasiewicz implication algebra, as a special case of LIA, plays a substantial role. By using ?ukasiewicz logic's axiomatizability in terms of Pavelka type fuzzy logic, we propose a new axiomatizable lattice ordered qualitative linguistic truth-valued logic system based on LIA to place an important foundation for further establishing formal linguistic truth-valued logic based approximate reasoning and decision making with applications. This proposed logic system has a distinct feature of handling comparable or incomparable linguistic terms directly without numerical quantification, will be especially beneficial for perception-based decision making processes. It attempts to enhance the quantitative theory of decision science with qualitative, algebraic and logic-oriented approaches to achieve reasoning with words. © 2014 Published by Elsevier Inc.

Chen S.,University of Ulster | Liu J.,University of Ulster | Liu J.,Southwest Jiaotong University | Wang H.,University of Ulster | And 2 more authors.
Information Sciences | Year: 2014

In real decision making problems, it is always more natural for decision makers to use linguistic terms to express their preferences/opinions in a qualitative way among alternatives than to provide quantitative values. Additionally, many of these decision making problems are under uncertain environments with vague and imprecise information involved. Following the idea of Computing with Words (CWW) methodology, we propose in this paper a linguistic valued qualitative aggregation and reasoning framework for multi-criteria decision making problems, where a linguistic valued algebraic structure is constructed for modelling the linguistic information involved in multi-criteria decision making problems, and a linguistic valued logic based approximate reasoning method is developed to infer the final decision making result. This method takes the advantage of handling the linguistic information, no matter totally ordered or partially ordered, directly without numerical approximation, and having a non-classical logic as its formal foundation for decision making process. © 2013 Elsevier Inc. All rights reserved.

Chen X.,Southwest Jiaotong University | Zhang J.,Southwest Jiaotong University
Neurocomputing | Year: 2011

Due to the limitation of the storage space in the real-world face recognition application systems, only one sample image per person is often stored in the system, which is the so-called single sample problem. Moreover, real-world illumination has impact on recognition performance. This paper presents an illumination robust single sample face recognition approach, which utilizes multi-directional orthogonal gradient phase faces to solve the above limitations. In the proposed approach, an illumination insensitive orthogonal gradient phase face is obtained by using two vertical directional gradient values of the original image. Multi-directional orthogonal gradient phase faces can be used to extend samples for single sample face recognition. Simulated experiments and comparisons on a subset of Yale B database, Yale database, a subset of PIE database and VALID face database show that the proposed approach is not only an outstanding method for single sample face recognition under illumination but also more effective when addressing illumination, expression, decoration, etc. © 2011 Elsevier B.V.

Zhou G.,Southwest Jiaotong University | Xu J.,Southwest Jiaotong University | Bao B.,Changzhou University
International Journal of Bifurcation and Chaos | Year: 2012

Peak Current-Mode (PCM) and Valley Current-Mode (VCM) controlled switching dc-dc converters have symmetrical dynamical behaviors within a wide circuit parameter variation range. To investigate the symmetrical dynamical behaviors between PCM and VCM controlled switching dc-dc converters, the iterative map models and inductor current borderlines that exist in the bifurcation diagrams of both PCM and VCM controlled buck, boost, and buck-boost converters are established. The research results of bifurcation behaviors indicate that the bifurcation diagrams of PCM and VCM controlled switching dc-dc converters have symmetrical dynamical behaviors corresponding to a symmetrical point (SP). The simulation results show that time-domain waveforms of PCM and VCM controlled switching dc-dc converters working in periodic orbits have symmetrical axis and SP, and the SP also exists in corresponding phase portraits. Experimental results are given to verify the analysis and simulation results in this paper. © 2012 World Scientific Publishing Company.

Wang H.,Southwest Jiaotong University | Zhang J.D.,University of Georgia | Schaefer III. H.F.,University of Georgia
ChemPhysChem | Year: 2010

Protonated base pairs were recently implicated in the context of DNA proton transfer and charge migration. The effects of protonating different sites of the guanine-cytosine (GC) base pair are studied here by using the DZP++ B3LYP density functional method. Optimized structures for the protonated GC base pair are compared with those of parent GC and the neutral hydrogenated GC radical (GCH). Proton and hydrogenatom additions significantly disturb the structure of the GC base pair. However, the structural perturbations arising from protonation are often less than those arising from hydrogenation of GC. Protonation of the GC base pair causes significant strengthening of the interstrand hydrogen bonds and a concomitant increase in the base dissociation energies. The adiabatic ionization potentials (AIPs), vertical ionization potentials (VIPs), and proton affinities (PAs) for the different protonation sites of the GC base pair are predicted. The N7 site of guanine is the preferred site for protonation of the GC base pair. © 2010 Wiley-VCH Verlag GmbH& Co. KGaA, Weinheim.

Yang B.,Southwest Jiaotong University | Zhao Y.,Southwest Jiaotong University
International Journal of Fatigue | Year: 2012

Behavior of dominant effective short fatigue crack, the crack results in the final failure of specimen, was experimentally investigated by a replica technique with seven smooth hourglass shaped specimens of railway LZ50 axle steel. Character of two-stages, i.e. the micro-structural short crack stage and the physical short crack stage, was revealed for the crack initiation and growth. Most importantly, the crack growth rate exhibited decelerations twice in micro-structural short crack stage. This behavior was related to the ferrite grain boundary firstly and then to the pearlite banded structure. The boundary appeared a barrier because there were pearlites around with significant higher micro-hardness values. Also because of the higher hardness values, the layered pearlite banded structure acted as another barrier for the crack to overcome. In physical short crack stage, the crack propagated with a decreasing resistance of micro-structural barriers as the crack length increased. Hence, the process of crack initiation and growth are subjected to the competition between the intrinsic resistances from the barriers and the increasing driving force from the growing crack size. Finally, a new short crack growth model is presented to describe the periodic influence of micro-structural barriers. Description to the test results of LZ50 steel has indicated the availability and reasonability of present model. © 2010 Published by Elsevier Ltd. All rights reserved.

Zhao Y.,Southwest Jiaotong University
International Journal of Fatigue | Year: 2012

An affordable and feasible method with moderate accuracy is developed to realize fatigue reliability assessment and life prediction including super long life regime (SLLR) through series of experimental researches on a railway axle steel and real axles. A competition damage mechanism for fatigue crack initiation and growth in SLLR is revealed to fascinate an understanding on wide fatigue damage behavior and to provide a weigh and balance on material primary quality control and on-line inspection capacity. Affordable material probabilistic strength-life (S-N) curves including SLLR are presented by an extrapolation approach on a concurrent probability rule between the S-N relations in mid-long life regime and the fatigue limits with a specified life definition. And then, structural probabilistic S-N curves are deduced by considering scale-induced effect on the material curves. Random cyclic stress-strain (CSS) relations are depicted for constructing structural random stressing history. Reliability assessment and fatigue life prediction are conducted by an interference model of the applied stress deduced from the random CSS relations and the strength capacity derived from the structural probabilistic S-N curves. Availability and feasibility of the present method are indicated by a successful application on a railway axle steel. © 2010 Published by Elsevier Ltd. All rights reserved.

Li P.D.,Southwest Jiaotong University | Li X.Y.,Southwest Jiaotong University | Zheng R.F.,Southwest Jiaotong University
Physics Letters, Section A: General, Atomic and Solid State Physics | Year: 2013

This Letter is concerned with thermo-elastic fundamental solutions of an infinite space, which is composed of two half-infinite bodies of different one-dimensional hexagonal quasi-crystals. A point thermal source is embedded in a half-space. The interface can be either perfectly bonded or smoothly contacted. On the basis of the newly developed general solution, the temperature-induced elastic field in full space is explicitly presented in terms of elementary functions. The interactions among the temperature, phonon and phason fields are revealed. The present work can play an important role in constructing farther analytical solutions for crack, inclusion and dislocation problems. © 2013 Elsevier B.V. All rights reserved.

Li X.L.,Southwest Jiaotong University | Liu D.,Southwest Jiaotong University
Lecture Notes in Electrical Engineering | Year: 2012

A modified general PID tuning fitness function based on evolutionary algorithm is proposed. Function is related to several mainly characters of controller response and system robustness. The simulation results show that the function is appropriate for PID tuning with PSO algorithm, the function is also appropriate for unstable time-delayed processes and has good convergence and distinguishability. Compared with ITAE, the PID controllers optimized by the function has better performance. © 2012 Springer Science+Business Media B.V.

Zhao W.,Southwest Jiaotong University
Lecture Notes in Electrical Engineering | Year: 2014

The database is the core and foundation of the information management system. And the database design is an important part in the design of information management system. The Web-based laboratory information management system selects Microsoft SQL Server 2000 as the database management system, object-oriented database structure design, from the three aspects of the data dictionary, ER diagram, and data table; the reasonable logic and physical design of the database greatly improves the system development efficiency and quality. © Springer-Verlag Berlin Heidelberg 2014.

Pennete K.C.,Southwest Jiaotong University
Lecture Notes in Electrical Engineering | Year: 2014

Web mining is the most pursued research area and often the most challenging one. Using web mining, corporates and individuals alike are inquisitively pursuing to unravel the hidden knowledge underneath the diverse gargantuan volumes of web data. This paper tries to present how a researcher can leverage the colossal knowledge available in open access sites such as Wikipedia as a source of information rather than subscribing to closed networks of knowledge and use open source tools rather than prohibitively priced commercial mining tools to do web mining. The paper illustrates a step-by-step usage of R and RapidMiner in web mining to enable a novice to understand the concepts as well as apply it in real world. © Springer-Verlag Berlin Heidelberg 2014.

Liu N.,Southwest Jiaotong University | Ma Z.,Southwest Jiaotong University | Kang J.,Tianjin University
Energy Policy | Year: 2015

The industrial sector accounts for 70% of the total energy-related CO2 emissions in China. To gain a better understanding of the changes in carbon intensity in China's industrial sector, this study first utilized logarithmic mean Divisia index (LMDI) decomposition analysis to disentangle the carbon intensity into three influencing factors, including the emission coefficient effect, the energy intensity effect, and the structure effect. Then, the analysis was furthered to explore the contributions of individual industrial sub-sectors to each factor by using an extension of the decomposition method proposed in Choi and Ang (2012). The results indicate that from 1996 to 2012, the energy intensity effect was the dominant factor in reducing carbon intensity, of which chemicals, iron and steel, metal and machinery, and cement and ceramics were the most representative sub-sectors. The structure effect did not show a strong impact on carbon intensity. The emission coefficient effect gradually increased the carbon intensity, mainly due to the expansion of electricity consumption, particularly in the metal and machinery and chemicals sub-sectors. The findings suggest that differentiated policies and measures should be considered for various industrial sub-sectors to maximize the energy efficiency potential. Moreover, readjusting the industrial structure and promoting clean and renewable energy is also urgently required to further reduce carbon intensity in China's industrial sector. © 2015 Elsevier Ltd.

Qu H.-L.,Southwest Jiaotong University | Zhang J.-J.,Southwest Jiaotong University
Yantu Gongcheng Xuebao/Chinese Journal of Geotechnical Engineering | Year: 2012

The research on seismic earth pressure is the core content of aseismic design of retaining walls. By investigating the seismic hazards induced by Wenchuan Earthquake, it is found that the retaining walls constructed on soil sites are easier to be damaged compared with those on rock sites. In view of this, it is very necessary to carry out researches on the influences of site conditions on the seismic earth pressures of retaining walls. But now, the codes for the aseismic design of railways and highways in many countries don't consider it. Large-scale shaking table tests, therefore, are performed to strengthen the understanding of the influences of site conditions on the seismic earth pressures of retaining walls. In the tests, the distribution of earth pressures, and the values and locations of resultant seismic earth pressures are measured. The reason for performing large shaking table tests is that the tests are the most direct research approach to study seismic responses of structures. In addition, by comparison of the measured and calculated values by codes for the aseismic design in several countries, some suggestions on the aseismic design of retaining walls are proposed.

Zhang Z.,Southwest Jiaotong University | Murray C.C.,Auburn University
International Journal of Production Research | Year: 2012

This paper presents a corrected formulation to the mixed integer programming model of the double-row layout problem (DRLP), first proposed by Chung and Tanchoco (2010, The double row layout problem. International Journal of Production Research, 48 (3), 709-727). In the DRLP, machines are placed along two rows of a corridor, where the objective is to minimise the total cost of material handling for products that move between these machines. We highlight the errors in the original formulation, propose corrections to the formulation, and provide an analytical validation of the corrections. © 2012 Copyright Taylor and Francis Group, LLC.

Wang Q.,Southwest Jiaotong University | Chu B.,Keio University | Wang J.,Tokyo Institute of Technology | Kumakiri Y.,Keio University
International Journal of Production Economics | Year: 2012

Flexible supply contracts with options have been proposed to supply chains with long lead-times, short selling seasons and high demand uncertainties to improve the performance. In this paper, we analyze the risks of introducing options, and find that even if providing a higher expected profit at the beginning of a planning horizon, supply contracts with options may have risks associated with a worse performance later compared with the traditional newsvendor contract model. We derive two important parameters for the buyer to estimate the risks of introducing options. One is a risk indicator that can show whether using options-based contract model has risks or not, and the other is a ratio to measure the probability of such risks. © 2010 Elsevier B.V. All rights reserved.

Li P.,Southwest Jiaotong University | Yang Y.,Southwest Jiaotong University | Xu W.,Southwest Jiaotong University
Nonlinear Dynamics | Year: 2012

Based on the potential theory of incompressible flow and the energy method, a two-dimensional simply supported thin panel subjected to external forcing and uniform incompressible subsonic flow is theoretically modeled. The nonlinear cubic stiffness and viscous damper in the middle of the panel is considered. Transformation of the governing partial differential equation to a set of ordinary differential equations is performed through the Galerkin method. The stability of the fixed points of the panel system is analyzed. The regions of different motion types of the panel system are investigated in different parameter spaces. The rich dynamic behaviors are presented as bifurcation diagrams, phase-plane portraits, Poincaré maps and maximum Lyapunov exponents based on carefully numerical simulations. © 2011 Springer Science+Business Media B.V.

Wan X.,Nanyang Institute of Technology | Liu J.,Southwest Jiaotong University
Proceedings of SPIE - The International Society for Optical Engineering | Year: 2011

Detecting and extracting the region of a license plate is the challenging first step in the vehicle license plate recognition system. In this paper, we propose a new approach for vehicle license plate localization using a Color Barycenters Hexagon (CBH) model. In CBH model, full color images are calculated the color barycenters and get the barycenters region, then automatic select the idea threshold curves to separate the Region of Interest (ROI) of barycenters aiming to localize the region of the vehicle license plate. Experimental results demonstrate that our method is effective, has strong practicability. Even if the practically images have many noise, our method can ideally localize vehicle license plate on various scene images when source image with suitably thresholding and operations. © 2011 Copyright Society of Photo-Optical Instrumentation Engineers (SPIE).

Ding J.-J.,Southwest Jiaotong University | Li F.,Southwest Jiaotong University
Tiedao Xuebao/Journal of the China Railway Society | Year: 2011

The force equilibrium equations of the wheelset with the initial deflection angle and radius difference were built, and the attack angles and lateral displacements of wheels, which with the LM, LMA and S1002 profile respectively, were calculated. Taking the China-made high speed train as an example, the dynamical model of vehicle was built. The influence of the initial deflection angle and radius difference on wheel wear were analyzed on the basis of the FASTSIM algorithm and Braghin wear model. The research results indicate as follows: The initial deflection angle has great effect on the attack angle and the radius difference has great effect on the lateral displacement; great attack angles and lateral displacements are evenmoreliable to be caused by the low equivalent conicity of the treed when manufacturing errors exist; serious eccentric wear is produced by the deflection angle and radius difference, the wear ratio increases rapidly with increasing of the deflection angle and radius difference; the larger the equivalent conicity of the tread, the smaller the wear ratio of the tread; the influence of the running speed on wheel wear is related to magnitude of the deflection angle and radius difference.

Xu P.,Southwest Jiaotong University | Cai C.-B.,Southwest Jiaotong University
Gongcheng Lixue/Engineering Mechanics | Year: 2011

A dynamic model of a train-ballast track-subgrade coupled system is established. In the model, spatial and time varying characteristics and interactions between the rolling stock, ballast track and subgrade are fully considered. The subgrade are modeled based on continuum theory and then be discretized by utilizing one of Galerkin methods. The model is reliable by comparing the calculation results with the test results in Qin-Shen passenger line. When the CRH2 EMUs passing at a speed of 200 km/h, the dynamic characteristics of subgrade are studied and analyzed. The dynamic responses such as the deformation and stress of subgrade surface, the dynamic deformation and stress distribution along the longitudinal and lateral directions are obtained. Such a model performs a fast calculation for the train-ballast track-subgrade coupled system, which can be used to study dynamic interactions between a train, ballast track and subgrade and make a detailed analysis about the dynamic characteristics of subgrade.

Zheng M.,University of Sichuan | Zhang H.,Southwest Jiaotong University | Xu D.,University of Sichuan
Journal of Physical Chemistry B | Year: 2012

Hyaluronate lyase from Spectrococcus pneumonia can degrade hyaluronic acid, which is one of the major components in the extracellular matrix. The major functions of hyaluronan are to regulate water balance and osmotic pressure and act as an ion-exchange resin. In this work, we focus on the prerequisite issue of the enzymatic reaction, i.e., the initial reactive conformer. Based on the quantum mechanical and molecular mechanical molecular dynamic simulations and free energy profiles, a near attack conformer was obtained for the degradation of hyaluronan catalyzed by the hyaluronate lyase. Along with the substrate binding, the phenylhydroxyl hydrogen atom of Tyr408 will transfer to nearby His399 via a near barrierless transition state, which results in a negatively charged Tyr408 and positively charged His399. The Tyr408, rather than the previously proposed His399, was suggested to act as the general base for the subsequent β-elimination reaction. The His399 was suggested to have the function of neutralizing the C5-carboxyl group. © 2012 American Chemical Society.

Wang B.,Southwest Jiaotong University
Advanced Materials Research | Year: 2014

This paper introduces the entire elevator controller making process based on the programmable chip EP2C8T144C8 through two softwares of QuartuesII and Altium Designer. It is different from the previous designs for the clocks of each part in this elevator controller all come from divisions of frequency of crystal oscillator, so that could be fully used. In addition, there is a lattice of 5×7 to achieve the state display. If the lattice makes the display run at 24 frames per-second, the human eye can catch it as a continuous image. © (2014) Trans Tech Publications, Switzerland.

Wu Z.,Southwest Jiaotong University | Chen X.,Southwest Jiaotong University | Zhu S.,Southwest Jiaotong University | Zhou Z.,Southwest Jiaotong University | And 3 more authors.
Sensors and Actuators, B: Chemical | Year: 2013

In this paper, we report conductometric sensors based on graphene/PANI nanocomposites, which were synthesized using chemical oxidative polymerization, for NH3 sensing. The experimental result reveals that the graphene/PANI sensor exhibits much higher sensitivity (ca. 5 times) than that of PANI, and shows approximate linearity over a wide range of concentrations from 1 to 6400 ppm. The detection limit of graphene/PANI sensor (ca. 1 ppm) is lower than that of PANI (ca. 10 ppm) for NH3. This shows that sensitivity of graphene/PANI sensor for NH3 detection is enhanced by the graphene added into PANI. The result is partially supported by experimental data that the NH3 adsorption of quartz crystal microbalance (QCM) coated graphene/PANI is larger than that of PANI. Meanwhile, the structure and morphology of the synthesized products are characterized by Fourier transform infrared spectroscopy (FTIR), brunauer emmett tellerand (BET), ultraviolet-visible spectroscopy (UV-vis), photoluminescence (PL), X-ray photoemission spectroscopy (XPS) and scanning electron microscopy (SEM), respectively. © 2013 Elsevier B.V.

Wang S.-R.,Huaqiao University | Ma Z.-J.,Southwest Jiaotong University
Xitong Gongcheng Lilun yu Shijian/System Engineering Theory and Practice | Year: 2011

To optimize emergency logistics system for post-earthquake emergency relief response, a twoechelon Location-Routing Problem (LRP) model was developed to decide emergency facility locationallocation and vehicle routes for relief materials delivery. According to the attributes of the model, a 'triangle' heuristic algorithm based on two-phase decomposition was proposed. The complexity of the algorithm was analyzed, and the heuristic algorithm was compared with an improved genetic algorithm. The computational results of a numerical example show that the model and algorithm can resolve LRP in post-earthquake emergency logistics system, and the advantage of the 'triangle' heuristic algorithm in computational efficiency.

Liu C.,Southwest Jiaotong University
Telecommunications Policy | Year: 2015

Traditionally, the role of telecommunications carriers is often limited to providing connections in rural informatization programs. This paper illustrates the case of Sichuan's government-carrier cooperative rural informatization model, where the carriers serve as both the information aggregator and distributor. A close historical analysis reveals that this seemingly unprofitable rural informatization service was originally conceived by competing carriers as a marketing strategy to gain a competitive advantage in less lucrative markets. However, when the government decided to promulgate such an informatization program nationwide, the business practice turned into one of the carrier's de facto obligations. Thus, Sichuan's model is a mixture of the passive fulfillment of political duty and the proactive pursuit of business interests. A sustainability failure analytical framework is applied to test the sustainability of Sichuan's model, which is found to be at risk of financial, social and institutional sustainability failures. © 2015 Elsevier Ltd.

Li N.,Southwest Jiaotong University | Pan W.,Southwest Jiaotong University | Locquet A.,Georgia Institute of Technology | Citrin D.S.,Georgia Institute of Technology
Optics Letters | Year: 2015

The concealment of the time-delay signature (TDS) of chaotic external-cavity lasers is necessary to ensure the security of optical chaos-based cryptosystems. We show that this signature can be removed simply by optically injecting an external-cavity laser with a large linewidth-enhancement factor into a second, noninjection-locked, semiconductor laser. Concealment is ensured both in the amplitude and in the phase of the optical field, satisfying a sought-after property of optical chaos-based communications. Meanwhile, enhancement of the dynamical complexity, characterized by permutation entropy, coincides with strong TDS suppression over a wide range of parameters, the area for which depends sensitively on the linewidth-enhancement factor. © 2015 Optical Society of America.

Guo Y.,Southwest Jiaotong University | Yan L.,Southwest Jiaotong University | Pan W.,Southwest Jiaotong University | Luo B.,Southwest Jiaotong University
Optics Express | Year: 2015

A dual-metasurface-based reflective device ("meta-mirror") has been proposed for broadband polarization manipulation, which is composed of orthogonal metallic cut-wire arrays separated from a grounded plane with different distances. The reflective phases of orthogonally linearly-polarized components can be independently adjusted by changing the dimensions of the cut-wire pairs. Benefiting from the fully released dispersion management ability in both dimensions, achromatic (i.e., ultra-broadband) polarization manipulation can be achieved. The suggested approach has been numerically verified in both microwave and optical band. Moreover, experimental characterization in microwave regime has demonstrated the broadband polarization manipulation ability within 5-30 GHz. The underlying physical mechanism of dispersion engineering was explained in general equivalent circuit theory and transmission line model. © 2015 Optical Society of America.

Li Z.,Southwest Jiaotong University | Yan L.,Southwest Jiaotong University | Shao L.,Southwest Jiaotong University | Pan W.,Southwest Jiaotong University | Luo B.,Southwest Jiaotong University
Optics Express | Year: 2015

Coherent Brillouin optical time domain analysis (BOTDA) sensing system with intensity modulated local (IML) light and fast IQ demodulation is proposed and demonstrated. IML light instead of phase modulated local (PML) light is utilized to reduce the coherent and multiple sidebands induced noises. A spatial resolution of 3-m and ± 1.8°C temperature accuracy at the far end of the fiber are obtained over 40-km sensing distance. © 2015 Optical Society of America.

Zhao H.,Southwest Jiaotong University | Wang H.,Southwest Jiaotong University | Khan M.K.,King Saud University
Signal Processing | Year: 2011

In this paper, we attempt to propose a novel blind steganalysis algorithm for palette-based images. First, the generalized difference images between adjacent pixels were constructed, and then the moments of characteristic functions of difference images histograms were extracted as features. Second, in order to measure the dependencies of neighboring colors, color correlogram technique is used to capture the global distribution of local spatial correlation of colors. The center of mass of the characteristic function of color correlogram and the absolute moments of autocorrelogram were extracted. Total of 13 dimension features were classified with machine learning technique. Number of experiments on several existing GIF steganography algorithms indicated that the proposed scheme is effective and gets good performance, especially when the embedding rate is not less than 20%. Experimental results also show that the average accuracy of our proposed scheme for different GIF steganography algorithms outperforms Lyus algorithm more than 20%. It also showed that the proposed scheme achieved similar performance with Fridrichs scheme and higher accuracies comparing to Dus algorithm and biologically inspired features. © 2011 Elsevier B.V. All rights reserved.

Li Z.,Southwest Jiaotong University | Yan L.,Southwest Jiaotong University | Shao L.,Southwest Jiaotong University | Pan W.,Southwest Jiaotong University | Luo B.,Southwest Jiaotong University
Optics Express | Year: 2015

An approach for reducing chromatic dispersion (CD) induced Brillouin gain spectrum (BGS) distortion and measurement instabilities in coherent Brillouin optical time domain analysis (BOTDA) sensing systems is proposed and experimentally demonstrated. By utilizing intensity modulated probe (IMP) instead of phase modulated probe (PMP), sensing performance is obviously improved. Reduction of ∼6-MHz decoding error caused by the CD induced BGS distortion is achieved in the measurement of Brillouin frequency shift (BFS) along the whole 40-km sensing distance. Enhanced system stabilities are demonstrated by testing the BGS under different conditions. © 2015 Optical Society of America.

Zhang J.-J.,Southwest Jiaotong University | Han P.-F.,Southwest Jiaotong University
Yantu Gongcheng Xuebao/Chinese Journal of Geotechnical Engineering | Year: 2012

The displacement-based design method is a frontier research topic in the aseismic field of geotechnical engineering. By means of large scale shaking table tests, the researches on displacement calculation modes of gravity retaining walls can provide supports for the displacement-based aseismic design method of gravity retaining walls. Firstly, the test scheme is introduced, including test equipments, mode design, testing procedures, seismic wave input and loading system. Secondly, the variation laws of displacements and displacement modes of retaining walls under different seismic intensities are studied, and then, the distribution of seismic earth pressure and its variation relationship with the displacement are also introduced. Based on Newmark's sliding block method and Zeng & Steedman's rotating block method, two models of sliding and rotating displacements are created separately. By comparing the calculated results of shaking table tests with those of empirical formulas, Whitman & Liao's mean fitting method is proposed to calculate the sliding displacement of gravity walls. Finally, the displacement-based aseismic design flow for gravity retaining walls is summarized.

Wang Y.-Y.,Southwest Jiaotong University | Ni S.-Q.,Southwest Jiaotong University
Tiedao Xuebao/Journal of the China Railway Society | Year: 2013

The train schedule is the basis of operation organization in urban rail transit. Against the background of the full-length & short-turn operation modes, train schedules of urban rail transit fix the number of train pairs running on every route in every period. In this paper, the methods for calculating passenger travel costs and enterprise operation costs with the full-length & short-turn operation modes were analyzed. The bi-objective nonlinear mixed integer programming model of the full-length & short-turn operation mode train schedules was established for urban rail transit. The objectives of the model were to minimize passenger travel costs and enterprise operation costs, and the constraints of the model were set as the shortest headway time interval of consecutive trains, passenger demand and the maximal available electric multiple units. The ideal point method was introduced to convert the above model into the single objective model and Lingo11.0 was then applied to solve the model. Validity of the model was verified by a numerical example. Sensitivity of cost related factors, such as turn-back stations and passenger flow proportion in short-turn sections, were analyzed. The results show as follows: Selection of short-turn mode turn-back stations affects costs significantly; the higher the passenger flow proportion in the short-turn sections, the more favorable for the full-length & short-turn operation modes to reduce costs.

Zhao C.-Y.,Southwest Jiaotong University | Wang P.,Southwest Jiaotong University
Tiedao Xuebao/Journal of the China Railway Society | Year: 2013

A promising means to reduce the components of railway rolling noises radiated by tracks is to increase the damping of the rails. This decreases the vibrations of the rails and thereby reduces the noises radiated. To achieve this, a silent rail with a slotted stand-off layer has been designed. The efficiency of the conventional constrained silent rail can be improved drastically by adding the slotted stand-off-layer (SOL) between the viscoelastic layer and the rail. It increases the viscoelastic strain so that more energy is dissipated via the viscoelastic layer. Suitable material and structure parameters have been found from extensive numeric tests. The prototype of it has been built and tested in the laboratory. Results are very promising with reductions of the acoustic radiation pressure level of rail noises to 8.2 dB (A) by vertical excitation and to 9.4 dB (A) by lateral excitation.

Both coverage and morphology of endothelial cells (ECs) on blood contact biomaterials were involved in the antithrombotic and anti-proliferative process. However, most researches have been focused on the ECs amount on the materials surface, but not the morphology. As of now, little is known about the relationship between the ECs morphology and the cytokine secretion, especially those anticoagulant factors on cardiovascular implants. In this study, three sizes of parallel micro-stripes of high molecular weight hyaluronic acid (HMW-HA) were fabricated on the NaOH-treated titanium (TiOH) surface. These micro-patterns of ridges/grooves were used to regulate the distribution, morphology and cytokine secretion of the ECs. The roughness of bare Ti and TiOH was detected by AFM, and the micro-pattern sizes were imaged by SEM. The chemical bonding of HMW-HA to the TiOH surface was demonstrated by FTIR, and the element distribution was examined by EDX. The morphology index of the ECs was analyzed to evaluate the orientation, elongation and spreading of the ECs on the micro-patterned surfaces and the control, while the cell number and cytokine secretion of the ECs were measured by related kits. The characterization of the ECs demonstrated that the bigger L/B index improved NO, PGI2, Fn release and TM, TFPI, E-Selectin expression as well as reducing vWF secretion. The platelet adhesion test and the whole blood clotting time test proved the increasing anticoagulation property of ECs with their elongation increasing. These results suggest that ECs morphology-related function can be regulated by different sizes of micro-patterns. Copyright © 2013. Published by Elsevier B.V.

Liu Y.,Southwest Jiaotong University | Zhao G.,Southwest Jiaotong University | Zhao G.,China Railway Corporation
Zhongguo Tiedao Kexue/China Railway Science | Year: 2013

Slab temperature gradient is obtained by observing the temperature field of slab under which CA mortar is grouting in different climate conditions. The warping deformation and stress of track structure under the action of measured temperature gradient is analyzed by building its mechanical calculation model. The results show that air temperature and solar radiation are the main influence factors on temperature gradient. Slab surface temperature plays the control effect on temperature gradient on which the hydration heat of CA mortar has some effects. The alternative variations of the warping compressive and tensile stress which can easily lead to the emergence of early gap between layers of track structure are caused by daily alternative variations of the positive and negative temperature gradient. There are two effective ways to reduce the early gap between the layers of track structure. Firstly, using effective heat insulation measures to control the slab surface temperature so that the early temperature field can be controlled to avoid large temperature warping stress which is due to large temperature gradient of slab. Secondly, prolonging as possible the demolish time for compaction device and fine adjustment jack according to strength increasing law of CA mortar.

Feng J.,Southwest Jiaotong University | Qiu W.,Southwest Jiaotong University | Wang Y.,Southwest Jiaotong University | Wang H.,Southwest Jiaotong University
Modern Tunnelling Technology | Year: 2013

For existing tunnels, there are many hazards that affect the durability of the tunnel structure. Based on a survey of nearly 2000 tunnels located in the Chengdu Railway Bureau, it was determined that construction time, conditions of the surrounding rock, classification of the environment, and lithology of the surrounding rock are the obvious factors affecting the distribution regularities of tunnel defects. This study is focused on the prevention of defects in surrounding rock of grades IV and V, the areas with developed ground water, and weak rock masses. Through field sampling and analysis, the human factors related to tunnel defects are discussed in terms of design, construction, and operation maintenance. Because of the particularity of tunnel structures, the current classification of environment is no longer suitable for tunnels and a new classification for general tunnel environments is discussed considering three basic indicators: the development of ground water, humidity inside the tunnel, and the lithology of the surrounding rock. Some countermeasures are put forward.

Zhao P.,Wuhan University | Wang W.,Southwest Jiaotong University | Sun M.,Wuhan University
Plant Cell, Tissue and Organ Culture | Year: 2011

The plant-specific "no apical meristem" genes are transcription factors that play diverse roles in plant development and stress responses. However, whether the gene family is also involved in somatic embryogenesis remains unknown, and no NAC family genes have been identified from orchid species. Here, we cloned and characterized a new member of NAC family from somatic embryos of Dendrobium candidum. Phylogenetic analysis indicated that DcNAC fell into the NAM subgroup based on similarities in protein sequence. Expression pattern analysis indicated that DcNAC exhibited a specific expression pattern in tissues examined, high levels of DcNAC mRNA was detected in protocorm-like bodies, and predominantly in the shoot apical meristem region as detected by in situ hybrization. Subcellular localization analysis showed that DcNAC protein is restricted in the nucleus through transient expression in Nicotiana benthamiana. Thus, DcNAC is the first NAC family gene isolated from orchid species, and our results provide the foundation for future investigations on the molecular mechanisms of somatic embryogenesis and for genetic improvement of Dendrobium candidum. © 2011 Springer Science+Business Media B.V.

Zhou D.,Southwest Jiaotong University | Zhang J.,Southwest Jiaotong University | Tang Y.,Southwest Jiaotong University
Yanshilixue Yu Gongcheng Xuebao/Chinese Journal of Rock Mechanics and Engineering | Year: 2010

Seismic damages of road slopes in mountainous areas have different characteristics in mechanism and types from those in flain. Based on cases of damaged road slopes in the Wenchuan earthquake, failure mechanisms and types of the road slopes for cutting and embankment slope and slopes around bridge and tunnel, as well as retaining structures, are analyzed. Slopes stabilized by using anchored foundation beams or lateral loaded piles with prestressed anchors have better performance in the earthquake. The reason is that these structures make both structures and soils become integral, and so deformation between structures and soil is consistent. Geogrid or other reinforced embankment slopes have better performance in the earthquake; but the aseismic performance of embankments without reinforcement, particularly high embankments, is poor. Based on the cases of liquefaction or soft soil layer-induced settlement, it is suggested that engineers in aseismic design should pay attention to liquefaction-induced settlement at the toe of the slopes constructed on sandy soil layers and take measures to prevent from pavement failure caused by the settlement on soft soil layers and slope instability caused by the settlement at the toe of the slope. At tunnel portals and portal slopes, engineers should strengthen aseismic design of retaining structures. Safety and stabilization of bridge abutment, foundation and transition between abutment and embankment constructed on slopes are dependent of the slope stability; and so aseismic design of the slope, on which those structures are constructed, should be strengthened. For bridges constructed along the bank of river, unstable slope can damage the bridges, some measures in aseismic design should, therefore, be taken into consideration. At present, codes for aseismic design of roads and railway have few contents for how to design slope and retaining structures; and so the achievements obtained will be helpful to revision and supplementary of the codes.

Xiao S.-G.,Southwest Jiaotong University
Yantu Gongcheng Xuebao/Chinese Journal of Geotechnical Engineering | Year: 2010

The distribution mode of landslide thrust on anti-sliding piles directly determines the internal forces and their distribution characteristics over the piles. So it has an important effect on the reasonability of design for the anti-sliding piles. Considering real design conditions for the anti-sliding piles in a practical project, pressure formulae of the landslide thrust are provided approximately by the limit equilibrium analysis on differential horizontal layer of sliding body in soil-like slopes or landslide projects. The formulae indicate that the distribution mode is parabolic along the longitudinal axis of direct anti-sliding segment of the pile with smaller value at its two ends than that at its middle part. The results of laboratory model tests on the limit status of sliding body movement show the approximate theoretical method given is realistic.

Zhang S.-C.,Xihua University | Zhang S.-C.,Southwest Jiaotong University
Physics Letters, Section A: General, Atomic and Solid State Physics | Year: 2013

It is revealed that at anti-resonance in a free-electron laser with a reversed guide magnetic field, the beam self-fields can act to focus the beam transport and prevent the electrons from striking on the waveguide wall before the wiggler exit. It is found that the focusing function results from the modulation of the periodically-varying self-field tangential and normal components on the electron's Larmor rotation. As a potential application, substantial improvement of the wave gain and output power at anti-resonance could be expected, since the beam current loss can be obviated by using this modulation mechanism. © 2012 Elsevier B.V. All rights reserved.

Gao F.,Southwest Jiaotong University | Liu D.,Southwest Jiaotong University
Modern Tunnelling Technology | Year: 2013

The origins of water inflow in the Xulingguan tunnel were identified using fuzzy cluster analysis and hydrochemical data from dynamic monitoring on-site. The fuzzy cluster analysis method was programmed using Excel VBA, making it simple to use and accurate regarding source identification, thereby achieving good results. This method provides a theoretical basis and technical support for prevention or remediation of water inflow in tunnels.

Yuan H.,Southwest Jiaotong University | Lu W.,University of Hong Kong | Jianli Hao J.,Ryerson University
Renewable and Sustainable Energy Reviews | Year: 2013

Construction waste comprises inert (e.g., sand, bricks, and concrete) and non-inert materials (e.g., bamboo, plastics, glass, wood, and paper). In Hong Kong, the inert portion can be deposited at public filling areas for land reclamation while the non-inert portion is disposed of at landfills. However, construction waste is usually a mixture of both inert and non-inert materials and thus a segregation of the two portions is of paramount importance for effective waste minimization. Previous studies have revealed that construction contractors in Hong Kong were unwilling to carry out on-site construction waste sorting (CWS) even though it has numerous advantages. After a decade, the situation should have changed, particularly given the promulgation of a waste charging scheme in 2006 imposing levies on different methods of construction waste disposal. This study thus aims at ascertaining the state-of-the-art on-site CWS practices in Hong Kong, with a particular interest in its evolution over the past ten years. Data was collected through case studies of six construction sites where a hybrid research method included a literature review, non-participant observations, and interviews. It was found that construction waste management (CWM) regulations have significantly enhanced on-site CWS in Hong Kong. Site space and project stakeholders' attitudes are still regarded as the most critical factors but labor and cost are no longer of major concerns in undertaking on-site CWS. Instead, a market for recyclables and an awareness of the profound environmental benefits are now perceived as being of major importance in these practices. Findings from the study can be used to review the effectiveness of current on-site CWS in Hong Kong, and through benchmarking they can also be used to develop good CWS practices in other economies. © 2012 Elsevier Ltd.

Fan N.,Southwest Jiaotong University | Chen G.X.,Southwest Jiaotong University
Tribology International | Year: 2012

A finite element model of a ceramic hip endoprosthesis system is established with ABAQUS 6.7 and the motion stability of the model is studied using the complex eigenvalue method. Numerical results reveal that a torsional vibration and a flexural vibration of the femoral component are responsible for squeaking. Increasing Youngs modulus of the stem, adding CoCrMo alloy as well as 316 L stainless steel in the stem and adding a whole damping layer of UHMWPE to the acetabular component can improve the vibrant stability of the system, then, suppress the squeaking. © 2012 Elsevier Ltd. All rights reserved.

Han K.,Southwest Jiaotong University | Yuan Y.J.,Southwest Jiaotong University
IEEE Sensors Journal | Year: 2014

The LOVE wave devices based on a number of composite structures have been designed and simulated in this paper for use as a bond-rupture biosensor. Bond-rupture biosensors use acoustic energy to probe the bond strength between the sensor substrate and the analyte. The sensitivity and displacement of LOVE wave sensors can be implemented due to energy concentration inside a guiding layer on the surface of a piezoelectric crystal. The choice of substrate and guiding layer material is the critical basic elements in the proper design of a LOVE wave biosensor applications. Finite element method (FEM) is a suitable numerical method to analyze and design the LOVE wave device. A 3-D FEM model has been created and defined to simulate the displacement response of the acoustic wave system. The LOVE wave can be clearly observed, and the total surface displacement can reach a value of \(10^{-11}\) m, which can easily induce the bond rupture between antibody and antigen. A 2-D model has been established to simulate the mass sensitivity with different composite structures of 128° YX LiNbO3, 36° YX LiTaO3, ST-quartz-PMMA and 128° YX LiNbO3, and 36° YX LiTaO3 and ST-quartz-SiO 2. These results indicate that the 128° YX LiNbO3PMMA is the most suitable for bond rupture biosensors due to its high sensitivity and maximum displacement on the surface of piezoelectric crystal. © 2001-2012 IEEE.

Li X.Y.,Southwest Jiaotong University | Zhao X.,Southwest Jiaotong University | Li Y.H.,Southwest Jiaotong University
Journal of Sound and Vibration | Year: 2014

This paper is concerned with the dynamic solutions for forced vibrations of Timoshenko beams in a systematical manner. Damping effects on the vibrations of the beam are taken into consideration by introducing two characteristic parameters. Laplace transform method is applied in the present study and corresponding Green's functions are presented explicitly for beams with various boundaries. The present solutions can be readily reduced to those for others classical beam models by setting corresponding parameters to zero or infinite. Numerical calculations are performed to validate the present solutions and the effects of various important physical parameters are investigated. © 2013 Elsevier Ltd.

Tan H.C.,Southwest Jiaotong University
Applied Mechanics and Materials | Year: 2014

As the progress of theory and computer technology, nonlinear analysis is widely applied in civil engineering. Strip method, as one of the numerical methods, is used widely especially in the analysis of beams, columns and shell structures. The first half of this paper introduces the theoretical model and the basic assumptions of the strip method; the latter half of this paper compiles the strip method into computer program using FORTRAN language. At last, using beams with rectangular cross-section of reinforced concrete structures as an example, the paper analyze the factors, such as the strength of the steel bars, which have an impact on the bearing capacity of reinforced concrete structures. © (2014) Trans Tech Publications, Switzerland.

Wu Y.F.,Zhejiang University | Chen W.Q.,Zhejiang University | Li X.Y.,Southwest Jiaotong University
Philosophical Magazine | Year: 2013

This paper presents a general account of the indentation responses of a one-dimensional hexagonal quasicrystal half-space pressed by an axisymmetric rigid punch. Based on Green's functions of the half-space subjected to point sources on the surface, the mixed boundary value problem is transformed to integral equations and solved exactly using the results of the potential theory method. Explicit expressions for the generalised pressures and indentation forces are derived for three common indenters (cylinder, cone and approximate sphere) in a systematic manner. For conical and spherical indenters, relations between the contact radius and indentation loads are determined. The coupling phonon-phason fields in the half-space under indentation are accurately expressed in terms of elementary functions. Numerical calculations are performed and discussions on related physical phenomena are given. The present exact solutions can serve as benchmarks for approximate or numerical analyses and can guide the experimental characterisation of material properties of quasicrystals. © 2013 Taylor & Francis Group, LLC.

Lu Y.,Southwest Jiaotong University | Rong Z.,Chinese Research Institute of Highway
Proceedings of the Institution of Civil Engineers: Transport | Year: 2016

The technique of placing hot-mix asphalt (HMA) overlay over a rubblised Portland cement concrete (PCC) pavement is a preferable way of rehabilitating severely deteriorated rigid pavements in south-west China. To investigate fragment size effects of the rubblised PCC on the performance of the HMA overlay, two full-scale experiments were carried out in a controllable environment. Strain development in the HMA was evaluated using data collected by strain sensors embedded at the overlay bottom. It was found that the performance of the overlay under repeated loadings was closely related to the fragment size distribution as well as the initial modulus of the rubblised PCC before the HMA was placed. For overlay paved over rubblised PCC with an insufficient amount of medium-sized fragments, tensile strains at the HMA overlay bottom increased with loading repetitions at a relatively high speed. However, if the fragments of rubblised PCC were graded relatively uniformly, particularly if the gradation matched the requirement for the crushed stone base of the flexible pavement, tensile strains at the HMA overlay bottom developed at a slower pace, indicating an improvement in the deterioration resistance of the overlay system to dynamic loads. © 2016, Thomas Telford Services Ltd. All rights reserved.

Xu J.,Southwest Jiaotong University | Wang J.,Southwest Jiaotong University
IEEE Transactions on Industrial Electronics | Year: 2011

A novel control technique, called bifrequency pulse-train (BF-PT) control technique, for switching dc-dc converters is proposed. In contrast to the conventional pulsewidth-modulation-based control technique of switching dc-dc converters, which realizes the output voltage regulation by adjusting the duty ratio of the control pulse cycle by cycle, the BF-PT control technique realizes the output voltage regulation of switching dc-dc converters based on the presence and absence of preset high- and low-frequency control pulses. In BF-PT control, the output voltage of switching dc-dc converter is sampled at the beginning of each switching cycle and compared with a reference voltage to determine whether a high- or low-frequency control pulse should be selected as the control pulse. The BF-PT control technique is simple and cost effective and enjoys fast transient response. In addition, two types of control pulses with different switching frequencies spread the emission spectrum over discrete frequencies, resulting in lower electromagnetic interference (EMI) noise and easier EMI filter design. Furthermore, more low-frequency control pulses at lighter load improve the light-load power conversion efficiency. A buck converter operating in discontinuous conduction mode is taken as an example to illustrate the application and benefits of BF-PT control technique. Simulation and experimental results are presented to verify the analytical results. © 2009 IEEE.

Zhang F.,Southwest Jiaotong University | Xu J.,Southwest Jiaotong University
IEEE Transactions on Industrial Electronics | Year: 2011

A novel pseudo-continuous conduction mode (PCCM) boost power-factor- correction (PFC) converter and its corresponding control strategy are proposed in this paper. Connecting a power switch in parallel with the inductor makes the boost converter operate in PCCM, which provides an additional degree of control freedom to realize PFC control. Therefore, a simple and fast voltage control loop of the PCCM boost PFC converter can be designed to realize output-voltage regulation. The additional degree of control freedom introduced by inductor current freewheeling operation of the PCCM boost PFC converter has been exploited through the dead-zone control technique, which can be dynamically adjusted in accordance with the output-voltage ripple. Compared with continuous conduction mode (CCM) boost PFC converter, the controller of the proposed PCCM boost PFC converter is much simpler. Moreover, the PCCM boost PFC converter benefits with reduced inductor-current ripple and improved power factor compared with boost PFC converter operating in discontinuous conduction mode (DCM). Analysis, simulation, and a 400-W prototype of the PCCM boost PFC converter have been presented and compared with those of boost PFC converters operating in conventional CCM and DCM. The results show that the dynamic response of the PCCM boost PFC converter is significantly faster than the existing boost PFC converter. © 2010 IEEE.

He C.,Southwest Jiaotong University
Applied Mechanics and Materials | Year: 2014

Based on a tunnel in western China as a project, with high water pressure, water-rich, karst features and other projects, launched grouting water research, the cement-silicate slurry mixing method for determining the mixing ratio to ensure the effectiveness and construction safety grouting key factors, as well as the specific implementation grouting effect evaluation method has important theoretical and practical value for the design and construction of similar tunnels provide a reference. © (2014) Trans Tech Publications, Switzerland.

Yang C.,Chongqing Three Gorges University | Huan S.,Southwest Jiaotong University | Yang Y.,Southwest Jiaotong University
World Transactions on Engineering and Technology Education | Year: 2015

The EPI-CDIO (Ethics, Professionalism, Integrity - Conceive, Design, Implement, Operate) teaching applied to engineering majors at local undergraduate colleges in China is a new, innovative educational concept. It not only values practice and application, it also makes up for the lack of instruction in professionalism, as well as ethical and professional integrity in higher engineering education. Presented in this article is an outline of EPI-CDIO training programmes and the teaching evaluation management systems, including the use of doubly qualified teacher teams. Special attention is paid to the cultivation of engineering students' humanistic quality in addition to fostering a solid professional foundation, strong project development, design, construction and engineering innovation ability. The results have been praised by teachers and students and have achieved good effects. © 2015 WIETE.

Deng Q.F.,Southwest Jiaotong University
Applied Mechanics and Materials | Year: 2014

The essence of Bashu traditional garden is a blend of north and south garden art and formed the unique style of landscape layout. Patch - corridor- matrix is applied in this article the traditional spatial pattern index analysis method to Bashu garden Xindu Guihu relative uniformity in the landscape diversity, landscape, landscape dominance index, landscape isolation, etc to study the spatial pattern characteristics and its ecological characteristics and related aspects of the evaluation, to Bashu provide quantitative reference value for the further study of the traditional garden. © (2014) Trans Tech Publications, Switzerland.

Liu X.,Southwest Jiaotong University | Pan W.,Southwest Jiaotong University | Zou X.,Southwest Jiaotong University | Luo B.,Southwest Jiaotong University | And 2 more authors.
Optics Express | Year: 2012

A novel optoelectronic oscillator (OEO) using cascaded recirculating delay lines (RDLs) is proposed and experimentally demonstrated. In the proposed OEO, instead of the use of an electronic microwave olter, two infinite impulse response (IIR) photonic microwave olters (PMFs) formed by two RDLs are employed to select oscillation frequencies. Specifically, an amplified spontaneous emission (ASE) source is adopted to avoid self-interference of each RDL, and two approximately equal gain RDLs are employed to reduce the influence of mutual interference between the two RDLs. Therefore, a stable microwave signal can be generated from the OEO loop. In the experiment, by tuning the lengths of RDLs, microwave signals at different frequencies, such as 194.1MHz, 648.5MHz and 2.99GHz, have been generated. The phase noise performance of the generated microwave signal is also investigated. The proposed approach has the potential for the generation of microwave signals up to tens of GHz with the use of integrated micro-ring devices. © 2012 Optical Society of America.

Li Y.,Southwest Jiaotong University | Qin K.,Southwest Jiaotong University | He X.,Southwest Jiaotong University
Information Sciences | Year: 2014

In this paper we propose two approaches to constructing divergence measures. The construction is based on the use of dissimilarity functions and fuzzy equivalencies. Firstly, we introduce some ways of generating dissimilarity functions. Then, we present several formulae of divergence measures. Finally, we examine the properties of divergence measures as a whole. © 2014 Elsevier Inc. All rights reserved.

Jiang L.-X.,Southwest Jiaotong University | Hou J.,Southwest Jiaotong University
Zidonghua Xuebao/Acta Automatica Sinica | Year: 2012

Automatic image annotation is an important but highly challenging problem in semantic-based image retrieval. In this paper, we formulate image annotation as a supervised learning image classification problem under the region-based image annotation framework. In region-based image annotation, keywords are usually associated with individual regions in the training data set. This paper presents a novel ensemble fast random rorest algorithm (FRF), which can classify a large number of training data effectively by bootstrap aggregation (Bagging) algorithm building multiple tree component classifier. The final result is obtained by component classifier voting. The proposed FRF algorithm is experimented on image annotation Corel data sets. Compared to classical algorithms, the FRF accelerates the operation speed of the algorithm, and the classification accuracy remains robust. It has a good application in automatic image annotation system. Copyright © 2012 Acta Automatica Sinica. All rights reserved.

He C.,Southwest Jiaotong University | Feng K.,Southwest Jiaotong University | Su Z.,Hong Kong Zhuhai Macao Bridge Authority
Yanshilixue Yu Gongcheng Xuebao/Chinese Journal of Rock Mechanics and Engineering | Year: 2011

According to the features of underwater shield tunnel with large cross-section, an integrated test method is proposed for prototype segmental lining structure, including joint structure and whole ring lining structure. The "Multifunction Shield Tunnel Structure Loading Test System" has been developed according to the test method. The system not only can perform the prototype test of segmental lining structure, but also can test the mechanics of joints. Then the test method and test system are applied to prototype tests for Nanjing Changjiang tunnel and Guangzhou Shiziyang tunnel. Meanwhile, joint bending stiffness and shear stiffness are both obtained successfully through a series of tests; and a part of results obtained by prototype tests is compared with numerical results to verify the accuracy and reliability of the test method and test system, so as to provide reliable test means for research, design and construction of underwater shield tunnel projects.

Li G.,Southwest Jiaotong University | Yang P.,Southwest Jiaotong University | Liao Y.,Southwest Jiaotong University | Huang N.,Southwest Jiaotong University
Biomacromolecules | Year: 2011

To improve the blood compatibility and endothelialization simultaneously and to ensure the long-term effectiveness of the cardiovascular implants, we developed a surface modification method, enabling the coimmobilization of biomolecules to metal surfaces. In the present study, a heparin and fibronectin mixture (Hep/Fn) covalently immobilized on a titanium (Ti) substrate for biocompatibility was investigated. Different systems [N-(3-dimethylaminopropyl)- N-ethylcarbodiimide and N-hydroxysuccinimide, electrostatic] were used for the formation of Hep/Fn layers. Atomic force microscopy (AFM) showed that the roughness of the silanized Ti surface decreased after the immobilization of Hep/Fn. Fourier transform infrared spectroscopy (FTIR), Toluidine Blue O (TBO) test, and immunochemistry assay showed that Hep/Fn mixture was successfully immobilized on Ti surface. Blood compatibility tests (hemolysis rate, APTT, platelet adhesion, fibrinogen conformational change) showed that the coimmobilized films of Hep/Fn mixture reduced blood hemolysis rate, prolonged blood coagulation time, reduced platelets activation and aggregation, and induced less fibrinogen conformational change compared with a bare Ti surface. Endothelial cell (EC) seeding showed more EC with better morphology on pH 4 samples than on pH 7 and EDC/NHS samples, which showed rounded and aggregated cells. Systematic evaluation showed that the pH 4 samples also had much better blood compatibility. All results suggest that the coimmobilized films of Hep/Fn can confer excellent antithrombotic properties and with good endothelialization. We envisage that this method will provide a potential and effective solution for the surface modification of cardiovascular implant materials. © 2011 American Chemical Society.

Jiang X.,Southwest Jiaotong University | Lyles R.W.,Michigan State University
Accident Analysis and Prevention | Year: 2010

In recent years, the quasi-induced exposure technique has been widely implemented in a variety of traffic safety-related settings. One of the primary concerns associated with the applications of quasi-induced exposure is that the underlying assumptions are not explicitly verified or validated before the exposure measurement is adopted. Of principal interest is the assumption that the non-responsible driver/vehicles in two-vehicle crashes are representative of the general driving population on the road at the time of crash occurrence. The objective here is to provide an alternative to test the not-at-fault assumptions with the use of three-or-more-vehicle crashes, which are readily available in many crash databases. With the use of Michigan and Maine crash data as examples, the examination of the validity is developed at two levels: (1) at all locations where crashes took place; (2) at locations where three-or-more-vehicle crashes are prone to occur. Non-responsible drivers are disaggregated by three basic driver-vehicle characteristics (age, gender, and vehicle type) and compared at these two levels for statistical and operational (practical) differences. Examination of the results demonstrates that all of the examined non-responsible driver distributions are consistently similar from both operational and statistical points of view. Compared to other approaches to validation, such as using "exposure truth" (e.g., actual vehicle miles traveled or a trip diary), the proposed validation is much more simplistic, straightforward, and cost-effective. © 2009 Elsevier Ltd. All rights reserved.

Li H.-C.,Southwest Jiaotong University | Hong W.,CAS Institute of Electronics | Wu Y.-R.,CAS Institute of Electronics | Fan P.-Z.,Southwest Jiaotong University
IEEE Journal on Selected Topics in Signal Processing | Year: 2011

In this paper, an efficient statistical model, called generalized Gamma distribution (GTD), for the empirical modeling of synthetic aperture radar (SAR) images is proposed. The GTD forms a large variety of alternative distributions (especially including Rayleigh, exponential, Nakagami, Gamma, Weibull, and log-normal distributions commonly used for the probability density function (pdf) of SAR images as special cases), and is flexible to model the SAR images with different land-cover typologies. Moreover, based on second-kind cumulants, a closed-form estimator for GTD parameters is derived by exploiting the second-order approximation for Polygamma function. Without involving the numerical iterative process for solutions, this estimator is computationally efficient and, hence, can make the GTD convenient for applications in the online SAR image processing. Finally, experimental results from tests carried out with actual SAR images demonstrate that the GTD can achieve better goodness of fit than the state-of-the-art pdfs. © 2011 IEEE.

Tang M.,Southwest Jiaotong University
International Journal of Electronics | Year: 2014

In this comment, an explicit form of the characteristic function for the extremal filter derived in a recent paper (Pavlović, V. D. (2013). Explicit form of new class of extremal filter functions with mini-max behaviour of summed sensitivity function. International Journal of Electronics, 100, 582-602) is corrected, and the restriction condition of its approximation expression is excluded. © 2014 © 2014 Taylor & Francis.

Zhou L.,Transport Bureau | Shen Z.,Southwest Jiaotong University
Journal of Modern Transportation | Year: 2011

This is a review of high-speed train development in the sense of technology advances all over the world. Three generations of high-speed trains are classified according to their technical characteristics and maximum operating speed. Emphasis is given to the newly developed high-speed train in China, CRH380. The theoretical foundations and future development of CRH380 are briefly discussed. © 2011 JMT. All rights reserved.

Qi T.,Southwest Jiaotong University | Gao B.,Southwest Jiaotong University
Journal of Modern Transportation | Year: 2011

To choose the optimum construction method of metro tunneling, we conducted research with numerical simulation on strata consolidation subsidence by dewatering, dynamic dewatering, and non-dewatering construction method, taking the integrated effects of fluid-solid coupling and tunneling mechanics into account. We obtained the curved surfaces of ground surface subsidence and strata consolidation subsidence. The results show that the quantity of ground surface subsidence is 31 mm for the non-dewatering method, 39 mm for the dynamic dewatering method, and 105 mm for the dewatering method. Their ratio is 1:1.3:3.4; and the percentages of strata consolidation subsidence to whole ground surface subsidence of each construction method is 27% (no-dewatering), 50% (dynamic dewatering), and 79% (dewatering). It is obvious that the non-dewatering construction method is the most effective method to control the strata consolidation subsidence induced by metro tunneling in saturated soft clay strata, and it has been successfully applied to the construction of the Shenzhen metro line 1. © 2011 JMT. All rights reserved.