西南交通大学学报

Advances in Anti-Doppler Effect Techniques for High Mobility Wireless Communications

FAN Pingzhi, ZHOU Weixi

2016, 29(3): 405-417. doi: 10.3969/j.issn.0258-2724.2016.03.001

[Abstract](931)

Abstract:
Doppler effect arising during a fast moving vehicle is very harmful to the wireless communications systems in high-speed trains and similar high mobility scenarios, affecting significantly the communication reliability and capacity. In this work, three categories of anti-Doppler effect techniques were analyzed, i.e., Doppler planning, Doppler compensation and Doppler utilization, especially the authors' recent work in Doppler utilization. In Doppler planning, the initial system design should ensure that the Doppler effect is reduced to a certain degree; in Doppler compensation, the Doppler offset should be firstly estimated accurately; then it can be greatly compensated or even canceled; as for Doppler utilization, it aims at collecting the potential Doppler diversity gains inherent in the time-varying channels, thus turning interference into assets.

Research on Security Risk Assessment for Traction Power Supply System of High-speed Railway

HE Zhengyou, FENG Ding, LIN Sheng, SUN Xiaojun

2016, 29(3): 418-429. doi: 10.3969/j.issn.0258-2724.2016.03.002

[Abstract](605)

Abstract:
To reduce security risk level of the traction power supply system of high-speed railway and achieve safe and reliable operation of high-speed railway in its life cycle, the security risk assessment for the traction power supply system of high-speed railway was summarized in the paper. The sources of security risk were expounded in three aspects:equipment performance decline,service environment and maintenance activities of operator. From the three aspects, the current research status on the risk assessment for power system and traction power supply system were summarized. With the rapid development of high-speed railway, such problems and challenges as incompleteness and uncertainty of data,complexity of service environment and lack of fault diagnosis and maintenance mode were analyzed. Future research on the security risk assessment was discussed, it is pointed out that the attention of the research on security risk assessment for traction power supply system should be paid to the following four aspects:data acquisition,assessment model,risk fusion and application of risk assessment.

Power System Design for a Fuel Cell Hybrid Power Tram

CHEN Weirong, BU Qingyuan, LIU Zhixiang, LI Qi, SUN Bangcheng, LI Ming

2016, 29(3): 430-436. doi: 10.3969/j.issn.0258-2724.2016.03.003

[Abstract](723)

Abstract:
Fuel cell hybrid power tram powered by hydrogen energy is a hot topic in the RD of modern tram. Based on the overall performance requirements of trams, the system design of a fuel cell/super-capacitor hybrid power tram was presented, including the overall design proposal and topological structure, the specification of hybrid power system and the calculation of the tram traction performance. Results demonstrate that the output power of the configured hybrid system can meet the dynamic requirements of two given driving cycles:accelerating from 0 to 35 km/h at an acceleration of 1.2 m/s2 and cruising at the maximum speed of 70 km/h. During the test under locomotive simulated drive cycle, the developed hybrid prototype can achieve energy distribution between different energy sources.

Current Following Segmented PID Control of Air Supply System in Heavy-Duty PEMFC System

LIU Zhixiang, LI Lun, HAN Zhe, PAN Jungang, DING Yi

2016, 29(3): 437-445. doi: 10.3969/j.issn.0258-2724.2016.03.004

[Abstract](554)

Abstract:
In order to optimize control effect of air compressor in a heavy-duty fuel cell system, a current following segmented PID control method for air supply system in a heavy-duty PEMFC (proton exchange membrane fuel cell) system was proposed based on centrifugal air compressor model. The method selects different PID parameters in dynamic response and steady state for closed loop control, and takes actual current as following goal based on the response characteristics of the centrifugal air compressor. The control effect was simulated and tested on the 150 kW fuel cell engine system developed in our laboratory. Simulation and experimental results indicate that the computation error of simulations is less than 5%, indicating that the model can reflect the character of the centrifugal air compressor and the air supply system; and the proposed current following segmented PID control method can fulfill dynamic control of the air supply system with response time of less than 3 s and good control effect.

Wireless Power Transfer Technology and Its Research Progress in Rail Transportation

MAI Ruikun, LI Yong, HE Zhengyou, YANG Mingkai, LU Liwen, LIU Yeran, CHEN Yang, LIN Tianren, XU Danlu

2016, 29(3): 446-461. doi: 10.3969/j.issn.0258-2724.2016.03.005

[Abstract](926)

Abstract:
Implementation of wireless power transfer (WPT) in traction power supply systems in rail transit could reduce maintenance cost and enhance safety dramatically, and hence is regarded as one of the most promising technologies in future traction power systems. First, technical characteristics of three main WPT technologies, i.e. radiative, capacitive, and inductive WPTs, are introduced with an emphasis on the working principle of the inductive WPT in rail transportation. Then, the current research status of WPT technologies for rail transit in China and abroad are reviewed. High-power high-frequency inverter, segmented power supply, magnetic coupler design, system optimization and control, and resonance stabilization are the key technologies and primary concerns in the progress of wireless power transfer in railway transportation. A detailed review on these technologies are also provided. Current trends of rail transportation-oriented WPT include development of high-power high-frequency resonant inverter, power supply segmentation, and system optimization. Researches in these key technologies will help boost WPT transfer power and efficiency, system stability, and engineering feasibility.

Overview and Prospect of T-S Fuzzy Control

XIAO Jian, ZHAO Tao

2016, 29(3): 462-474. doi: 10.3969/j.issn.0258-2724.2016.03.006

[Abstract](1048)

Abstract:
T-S fuzzy control can deal with complicated nonlinear systems, and has been successfully applied to a lot of industrial fields. From the aspects of modeling, stability analysis, and controller design, the current research status of the type-1 T-S fuzzy control and the interval type-2 T-S fuzzy control are reviewed, with an overall elaboration on the conservativeness issue in analysis and design of type-1 T-S fuzzy systems, type-1 T-S fuzzy polynomial systems, and interval type-2 T-S fuzzy systems. A discussion is also made on the principles of the slack variable approach, the parameter dependent Lyapunov function approach and the membership-function-shape-dependent approach, as well as their applications to reduce conservativeness of the fuzzy feedback controller. In addition, from the aspects of modeling of type-1 T-S fuzzy systems and the parameter dependent Lyapunov function design approach of interval type-2 T-S fuzzy systems, prospects on the T-S fuzzy control are described. The further research directions may include the output feedback control of type-1 T-S fuzzy polynomial systems, the interval type-2 T-S fuzzy systems with time-delays, the robust control and model reduction of interval type-2 T-S fuzzy systems, and the hardware implementation and engineering applications of the proposed approaches.

Resonant single-switch multi-string boost LED driver converter

XU Jianping, YANG Qi, LIU Xueshan

2016, 29(3): 475-486. doi: 10.3969/j.issn.0258-2724.2016.03.007

[Abstract](469)

Abstract:
A novel resonant single-switch multi-string boost LED driver converter was proposed, the operation principle and characteristics of which were analyzed. It can achieve current balancing among 2n LED strings by using only one active switch, one resonant inductor and 2n-1 resonant capacitors. Thus it boasts the benefits of simple circuit structure and control, small volume, high efficiency and low cost. By controlling only one output current, the other output currents of this LED driver can be controlled utilizing the charge balance principle of resonant capacitors. If one output branch of the LED driver is short-circuit in the steady state, it will not affect current sharing among the other output currents. Therefore, it has a characteristic of natural short-circuit protection. Finally, the theoretical analysis is verified by a 48 W four-string prototype.

Correlation between Winding Temperature Rise and Oil Flow in Traction Transformer

ZHOU Lijun, LI Jinping, YANG Yang, JIANG Junfei, WANG Lujia, WANG Dongyang

2016, 29(3): 487-494. doi: 10.3969/j.issn.0258-2724.2016.03.008

[Abstract](592)

Abstract:
To clarify the dynamic relationship between winding temperature rise and flow velocity under traction loads, a special temperature rise test platform for traction transformer was set up. By the test platform the temperature of oil, the winding hot spot as well as oil flow velocity in radiator can be measured at the same time, when the test platform worked under various simulated traction loads. Then a numerical model was established, which was validated by experiment. The results show that flow velocity is proportional to the winding temperature under steady state; oil flow velocity has a shock-down process under step load, the peak of oil flow velocity is affected by load acting time and load factor, the peak time is later 10 minutes than the winding hot spot temperature; under continuous impulsive load, the temperature and velocity before impulsive load affect the absolute value of the hot spot temperature only, while have little effect on the temperature difference between copper and oil.

Advances of Research on High-speed Railway Catenary

LIU Zhigang, SONG Yang, HAN Ye, WANG Hongrui, ZHANG Jing, HAN Zhiwei

2016, 29(3): 495-518. doi: 10.3969/j.issn.0258-2724.2016.03.009

[Abstract](808)

Abstract:
Dynamic interaction between the catenary and the pantograph is one of the most crucial factors that affect the train operation in high-speed railways. The adverse state of catenary directly influences the power supply safety of traction power system. In this work, four aspects in the research of high-speed railway catenary system were reviewed in detail, namely, the solution methods for the initial equilibrium state of catenary, the dynamic modelling, non-contact detection, and the static and dynamic evaluation. In addition, their recent advances were presented. To deal with the low solution accuracy of the initial equilibrium state of catenary, both the structure finding method with multi-objective constraints and nonlinear finite element procedure were introduced. For the catenary's dynamic modelling, the influence of environmental wind on the catenary was taken into account; based on the environmental wind simulation and wind tunnel test, the aerodynamic coefficients were obtained and the wind field along the catenary was built to analyze wind vibration characteristics of catenary. In order to improve the accuracy of non-contact detection for the catenary, the deep learning theory and real-time detection algorithms can be utilized in future. As for the lack of dynamic evaluation method for the catenary, the modern spectrum estimation, time-frequency analysis, big data technology and their combinations will be the important means for future catenary evaluation.

New Development of CAE Platform and Computational Mechanics Software

FENG Zhiqiang, LIU Jiantao, PENG Lei, ZHOU Yangjing, NING Po, WANG Bo

2016, 29(3): 519-524. doi: 10.3969/j.issn.0258-2724.2016.03.010

[Abstract](653)

Abstract:
Numerical modeling is a powerful tool to solve complex engineering problems. One of significant requirements in the design of a scientific computing program is the ability to store, retrieve, and process data that maybe complex and varied. To the users, it is important not only to have a powerful solver, but also to work in a convivial graphical interface environment. It is so important to develop a general and open CAE platform with friendly graphical user interfaces. This paper presents the new progress of our research team in developing the CAE software platform OmtDesk. Using Qt+OpenGL and C++ Object-Oriented Programming (OOP) techniques, this platform includes a friendly User Graphical Interface (GUI) and it could be run on multi-systems. As an example, a solid mechanics computational software is developed based on the platform and user interface. It shows that the software design concepts proposed in this paper are valuable and the CAE platform has already powerful features.

Influences of High-Speed Railway Construction on Railway Transportation of China

PENG Qiyuan, LI Jianguan, YANG Yuxiang, WEN Chao

2016, 29(2): 525-533. doi: 10.3969/j.issn.0258-2724.2016.03.011

[Abstract](717)

Abstract:
Large-scale construction and operation of high-speed railway in China have achieved outstanding results in improving the network scale and quality, alleviating the shortage of transport capacity, and improving the quality of rail transport services. This paper summarizes the influences of high-speed railway systematically from the aspects of promotion of railway network conditions in structure and scale, improvement of transport service capacity, establishment of express passenger and freight network, and construction of modern integrated passenger transportation hub. The high-speed railway construction has greatly boosted theoretical and methodological innovations in railway transport organization mode, timetabling, overnight trains operation, EMU operation scheduling, and high-speed rail dispatching; and promoted the infrastructure construction technologies and EMU manufacturing and control technology. Therefore, the construction of high-speed railway plays an important role in supporting the sustained and rapid development of China's national economy. All these achievements provide a good theoretical support for implementation of China's national strategies of One Belt and One Road and Export of high-speed rail technologies.

Research on Stochastic Behavior of Traffic flow

ZHANG Jiye, ZHENG Weifan

2016, 29(3): 534-545. doi: 10.3969/j.issn.0258-2724.2016.03.012

[Abstract](553)

Abstract:
With the increase of population and vehicles, the development of roads is difficult to meet the needs of vehicle traffic, traffic congestion and other issues become serious. Due to the dynamic, stochastic, non-linear and multi-behavior subject characteristics of traffic flow, the complexity of traffic flow is increased. Therefore, research on the stochastic behavior of traffic flow is important for understanding the intrinsic evolution rules of traffic systems. At present, a series of models were established in this field, the corresponding theoretical systems were formed, and continuously be applied in traffic. In this paper, the stochastic behavior of traffic flow is reviewed, the main method and development condition of various kinds of theoretical models are discussed. These models mainly include independent interactional models, such as the microscopic following models, the macroscopic fluid dynamics models, the mesoscopic gas dynamic models, the cellular automatic models. Interactional models, such as the interactional potential models and the weighted interactional potential models et al. Based on the summary and analysis of the present research, the future research on stochastic impact factors and the analysis of stochastic dynamics of traffic flow is prospected.

Literature Review on Surrogate Exposure Technique: Quasi-induced Exposure

JIANG Xinguo, ZHANG Guopeng, BAI Wei, XIA Liang

2016, 29(3): 546-552. doi: 10.3969/j.issn.0258-2724.2016.03.013

[Abstract](588)

Abstract:
Traffic safety has become one of the most critical issues in the social development. In the traditional exposure measurement, vehicle miles traveled is the most frequently used technique. The issues associated with the use of quasi-induced exposure are that it lacks the systematic data screening process and theoretical validation on the underlying assumptions. In the meanwhile, there are problems of using the non-driving related behaviors or traffic tickets in the assignment of crash responsibility. The application of quasi-induced exposure theory is able to quantify the crash propensity of the driving cohorts and thus accurately reflect the varying spatial and temporal conditions of crash environments and the discrepancy of the driving populations. In the future development of quasi-induced exposure, the research should be directed to develop the systematic procedure to screen crash data, conduct statistical methods to reveal inherent problems of crash data, and stipulate the according schemes to manipulate the data. From the aspect of responsibility assignment, the research should introduce weights into the causal factors, and assign the faults to the involved drivers through the fault-assignment models. Finally, the authors attempt to establish the application guidelines of quasi-induced exposure through the theoretical validations on the assumptions.

Recognition of Traffic Congestion Based on Mobile Phone Sensor Data

XIAO Feng, TU Wenwen, CHEN Dong

2016, 29(3): 553-562. doi: 10.3969/j.issn.0258-2724.2016.03.014

[Abstract](589)

Abstract:
Accurate recognition of traffic congestion is the basis of intelligent transportation system. This study develops a new method to evaluate the running environment surround the target vehicle based on two parameters:the real-time acceleration and angular acceleration collected from the smart phone. After analyzing the statistical characteristics of the parameters, the data is found to have a close relationship with the corresponding traffic flow states. Support vector machine and parametric optimization method are utilized to test these data. The experiments show a highest accuracy of 92%, indicating that acceleration and angular acceleration could be considered together as the characterization parameters of traffic flow states. To reduce the computation cost while maintaining the accuracy of the traffic state identification, strong explanatory variables of the support vector machine algorithm are recognized by the relative optimal regression model and the least angle regression method.

Equity Allocation Method of Logistic Resources Based on Variable Weights

ZHANG Jin, ZENG Qian, CHEN Yiyou

2016, 29(3): 563-570. doi: 10.3969/j.issn.0258-2724.2016.03.015

[Abstract](502)

Abstract:
The influences of individual weights and output efficiencies on logistic resources allocation were studied with fixed and variable weights. It shows that the lacking individual get a high weights under variable weights, which results in a high level of equity. Based on the above, a new method was proposed to achieve allocation equity. A variable weights function was built to calculate the weight of the individual. It is constructed by variable weights, individual utility functions and constant weights. The optimum allocation can be selected by comparing the total utilities of all feasible solutions. Changing variable weights parameters can achieve the tradeoff between efficiency and equity, including optimization efficiency, max-min fairness or other equity degrees. The parameters can be determined by the loss on efficiency and equity. An example of emergency resources allocation demonstrated the validity of this method and illustrated the influence of parameters on weights, efficiencies and equity.

New Strategies for Developing Cardiovascular Implanted Devices Surfaces with In situ Construction of Vascular Endothelial Growth Microenvironment

HUANG Nan, LI Jing'an, WEI Lai, LI Shiqi, SU Hong, LÜ, Xianfeng, CHEN Junying, YANG Ping

2016, 29(2): 571-584. doi: 10.3969/j.issn.0258-2724.2016.03.016

[Abstract](521)

Abstract:
Thrombosis and restenosis at the site of implanting cardiovascular devices remains a significant long-term problem in the practice of interventional cardiology. Recent researches show that vascular endothelial functional reconstruction at the injury site can significantly reduce the restenosis ratio and avoid the thrombosis. This process is closely related to the endothelial cells growth microenvironment, such as the pericytes environment, the underlying tissue topology and the extracellular matrix microenvironment. In this contribution, we systematically discussed the influence of these three factors on the reconstruction of the endothelial function on the cardiovascular implanted materials, and presented our recent research progress on the in situ and bionic construction of endothelial cells growth micro-environment on the materials surface. As for constructing the pericytes environment, contractile smooth muscle cells were introduced to promote functional factors release from the endothelial cells. To simulate the native topology of the vessel wall, micro-patterns and/or nano structures were fabricated on to the surface to regulate the morphology and distribution of the endothelial cells. Decellularization and biomolecular conjugating were applied to obtain extracellular matrix and further improve surface biocompatibility.

Research Status and Development on Latent Energy Storage Technology of Building

YUAN Yanping, XIANG Bo, CAO Xiaoling, ZHANG Nan, SUN Liangliang

2016, 29(2): 585-598. doi: 10.3969/j.issn.0258-2724.2016.03.017

[Abstract](932)

Abstract:
As an important building energy saving technology, latent energy storage technology can solve the mismatch between energy supply and demand in time,space and strength. The preparation and thermal conductivity enhancement of building energy storage phase change materials, the heat transfer characteristics and enhancement of a phase change unit, the development and application of building phase change energy storage system are reviewed. The deficiency of materials research and development, system performance evaluation and system application technology development is summarized, and this paper points out the focus of further research, namely, developing the phase change materials with stable performance and strong heat storage or release capability, predicting dynamic performance of multi-physical processes and multi-phase energy storage system effectively and achieving an objective that the energy storage system could run independently and effectively without human intervention.

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2016 Vol. 29, No. 3