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Adaptive QoS Management for Delivering Scalable Video over OFDM Svstem

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Adaptive QoS Management for Delivering Scalable Video over O...

Fault Diagnosis for High Order LTI Systems Based on Model Decomposition

IEEE 2007 International Symposium on Microwave,Antenna,Propagation and EMC Technologies for Wireless Communications(ISMAPE-2007)

作者： Qing Huang~1,Xin Sun~1,Yuan Zhang~2 1 state key laboratory of rail traffic control and safety(beijing jiaotong university) beijing,100044,china 2 Communication university of china,beijing,100024,china

This paper proposes an adaptive QoS management framework for delivering scalable video over OFDM *** proposed framework has two advantages:One is to admit as many base layer video streams as possible while meeting the hard guarantees for all base layer video streams,the other is to adapt the enhancement layer video streams based on the available residual resources to provide the same quality improvement among the admitted *** results show that the system resources are shared in a fair manner while perceptual quality is degraded gracefully under severe channel conditions and new call.

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Fault Diagnosis for High Order LTI Systems Based on Model De...

Optimization model and algorithm for mixed traffic of urban road network with flow interference

第24届中国控制与决策会议

作者： Lihua Liu 1 , Xiukun Wei 2 , Xiaohe Liu 1 1. Institute of Automation, beijing Information Science and Technology university, beijing 100192, china2. state key laboratory of rail traffic control and safety, beijing jiaotong university, beijing 100044, china

Fault detection observer and fault estimation filter are the main tools for the model based fault diagnosis approach. The dimension of the observer gain normally depends on the system order and the system output dimension. The fault estimation filter traditionally has the same system dimension of the monitored system. For high order systems, these methods have the potential problems such as parameter optimization and the real implementation on-board for applications. In this paper, the system dynamical model is first decomposed into a special structure. With the new model, a fault detection system can be designed such that only the residuals with the same dimension as the size of the faults are sensitive to the faults. The rest residuals are totally decoupled from the faults. A lower order （with the same size of the fault） fault estimation filter design approach is proposed. Further, the design of a static fault estimation matrix is presented for further improving the fault estimation precision. The proposed method is demonstrated by a simulation example.

关键词： Fault diagnosis high order model decomposition observer filter

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Science china(Technological Sciences) 2008年第12期51卷 2213-2222页

作者： SI BingFeng,LONG JianCeng & GAO ZiYou state key laboratory of rail traffic control and safety,beijing jiaotong university,beijing 100044,china state key laboratory of rail traffic control and safety Beijing Jiaotong University Beijing 100044 China

In this paper,the problem of interferences between motors and non-motors in urban road mixed traffic network is considered and the corresponding link impedance function is presented based on travel *** the base of this,the main factors that influence travelers' traffic choices are all considered and a combined model including flow-split and assignment problem is *** a bilevel model with its algorithm for system optimization of urban road mixed traffic network is *** the application of the model and its algorithm is illus-trated with a numerical example.

关键词： mixed traffic impedance function user equilibrium optimization

Solving the constrained shortest path problem using random search strategy

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Science china(Technological Sciences) 2010年第12期53卷 3258-3263页

作者： LI KePing, GAO ZiYou , TANG Tao & YANG LiXing state key laboratory of rail traffic control and safety, beijing jiaotong university, beijing 100044, china 1. state key laboratory of rail traffic control and safety Beijing Jiaotong University Beijing 100044 China

In this paper, we propose an improved walk search strategy to solve the constrained shortest path problem. The proposed search strategy is a local search algorithm which explores a network by walker navigating through the network. In order to analyze and evaluate the proposed search strategy, we present the results of three computational studies in which the proposed search algorithm is tested. Moreover, we compare the proposed algorithm with the ant colony algorithm and k shortest paths algorithm. The analysis and comparison results demonstrate that the proposed algorithm is an effective tool for solving the constrained shortest path problem. It can not only be used to solve the optimization problem on a larger network, but also is superior to the ant colony algorithm in terms of the solution time and optimal paths.

关键词： constrained shortest path deterministic random walk optimization

Urban expressway traffic state forecasting based on multimode maximum entropy model

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Science china(Technological Sciences) 2010年第10期53卷 2808-2816页

作者： SUN XiaoLiang1,2, JIA LiMin1, DONG HongHui1, QIN Yong1 & GUO Min3 1state key laboratory of rail traffic control and safety, beijing jiaotong university, beijing 100044, china 2School of traffic and Transportation, beijing jiaotong university, beijing 100044, china 3beijing traffic Management Bureau, beijing 100044, china 1. state key laboratory of rail traffic control and safety Beijing Jiaotong University Beijing 100044 China2. School of Traffic and Transportation Beijing Jiaotong University Beijing 100044 China3. Beijing Traffic Management Bureau Beijing 100044 China

The accurate and timely traffic state prediction has become increasingly important for the traffic participants,especially for the traffic managements. In this paper,the traffic state is described by Micro-LOS,and a direct prediction method is introduced. The development of the proposed method is based on Maximum Entropy (ME) models trained for multiple modes. In the Multimode Maximum Entropy (MME) framework,the different features like temporal and spatial features of traffic systems,regional traffic state are integrated simultaneously,and the different state behaviors based on 14 traffic modes defined by average speed according to the date-time division are also dealt with. The experiments based on the real data in beijing expressway prove that the MME models outperforms the already existing model in both effectiveness and robustness.

关键词： traffic state forecast maximum entropy model multimode

Performance analysis of uplink MIMO MC-CDMA systems based on linear zero-forcing V-BLAST algorithm

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Science in china(Series F) 2008年第9期51卷 1305-1318页

作者： YANG Wei1,2 & YANG Wei1 1 state key laboratory of rail traffic control and safety,beijing jiaotong university,beijing 100044,china 2 National Mobile Communications Research laboratory,Southeast university,Nanjing 210096,china 1. state key laboratory of rail traffic control and safety Beijing Jiaotong University Beijing 100044 China 2. National Mobile Communications Research laboratory Southeast University Nanjing 210096 China

A structure was proposed for multiple-input-multiple-output multicarrier code divi- sion multiple access （MIMO MC-CDMA） uplink transmission system. Linear zero- forcing V-BLAST （ZF V-BLAST） algorithm and maximum ratio combining （MRC） scheme was applied to the receivers. The average bit error rate （BER） expression was derived on condition that the number of receive antennas was larger than that of transmit antennas and it was verified by simulations. Numerical results show that the number of transmit and receive antennas, as well as the number of sub- carriers, all exert significant effects on the BER performance. The space diversity and frequency diversity show different abilities to improve the BER performance. The MIMO MC-CDMA system based on linear ZF V-BLAST algorithm is capable of achieving better BER performance than that of the conventional MC-CDMA system by reducing the number of transmit antennas or increasing the number of receive antennas.

关键词： bit error rate(BER) multiple-input-multiple-output(MIMO) multicarrier code division multiple access(MC-CDMA) zero-forcing(ZF)

Experiments and sensitivity analyses for heat transfer in a meter-scale regularly fractured granite model with water flow

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Journal of Zhejiang university-Science A(Applied Physics & Engineering) 2012年第12期13卷 958-968页

作者： Wei LU1,2,Yan-yong XIANG1 (1School of Civil Engineering,beijing jiaotong university,beijing 100044,china) (2state key laboratory of Simulation and Regulation of Water Cycle in River Basin,china Institute of Water Resources and Hydropower Research,beijing 100038,china) 1. School of Civil Engineering Beijing Jiaotong University Beijing 100044 China 2. state key laboratory of Simulation and Regulation of Water Cycle in River Basin China Institute of Water Resources and Hydropower Research Beijing 100038 China

Experiments of saturated water flow and heat transfer were conducted for a meter-scale model of regularly fractured granite. The fractured rock model （height 1502.5 ram, width 904 mm, and thickness 300 mm）, embedded with two vertical and two horizontal fractures of pre-set apertures, was constructed using 18 pieces of intact granite. The granite was taken from a site currently being investigated for a high-level nuclear waste repository in china. The experiments involved different heat source temperatures and vertical water fluxes in the embedded fractures either open or filled with sand. A finite difference scheme and computer code for calculation of water flow and heat transfer in regularly fractured rocks was developed, verified against both the experimental data and calculations from the TOUGH2 code, and employed for parametric sensitivity analyses. The experiments revealed that, among other things, the temperature distribution was influenced by water flow in the fractures, especially the water flow in the vertical fracture adjacent to the heat source, and that the heat conduction between the neighboring rock blocks in the model with sand-filled fractures was enhanced by the sand, with larger range of influence of the heat source and longer time for approaching asymptotic steady-state than those of the model with open fractures. The temperatures from the experiments were in general slightly smaller than those from the numerical calculations, probably due to the fact that a certain amount of outward heat transfer at the model perimeter was unavoidable in the experiments. The parametric sensitivity analyses indicated that the tem- perature distribution was highly sensitive to water flow in the fractures, and the water temperature in the vertical fracture adjacent to the heat source was rather insensitive to water flow in other fractures.

关键词： Fractured granite Water flow Heat transfer Physical modeling Numerical calculation Sensitivity analysis

AFM study on the adsorption and aggregation behavior of dissolved humic substances on mica

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Science china Chemistry 2006年第3期49卷 256-266页

作者： GE Xiaopeng1, ZHOU Yanmei2, Lü Chunhua1 & TANG Hongxiao1 1. state key laboratory of Environmental Aquatic Chemistry, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, beijing 100085, china 2. School of Civil Engineering & Architecture, beijing jiaotong university, beijing 100044, china 1. state key laboratory of Environmental Aquatic Chemistry Research Center for Eco-Environmental Sciences Chinese Academy of Sciences Beijing 100085 China 2. School of Civil Engineering & Architecture Beijing Jiaotong University Beijing 100044 China

Humic substances constitute the major organic fractions of soils, sediments and natural waters, and play a dominant role in the binding, mobilization, transport and ultimate fate of organic contaminants in subsurface systems. In this paper, two humic acid samples, Guanting and Tianjin, with different origin and chemical compositions have been investigated with AFM imaging for their adsorption and aggregation behaviors on mica. While the Tianjin humic sample is found to form small spheres with 250 to 330 nm in diameter at lower concentrations, irregular loop-chain assemblies of hundreds of nanometer in diameter with the chain width of about 40 nm are dominant for the Guanting humic sample, which may attribute to the more polar aliphatic fractions in the chemical composition in the latter. The heterogeneous and polydisperse nature of humic substances with multiple structural features, such as sponge-like structures, perforated sheets, aggregate of spheres, branches and chain-like assemblies etc., is apparent at higher concentrations for both humic samples, showing morphologically new evidence for the dominant view of the humic dual-mode sorption model. With naphthalene introduced, the assemblies of Guanting humic substances clearly become more compact with significantly narrowed branches and less porous the perforated sheet-like structures. It is indica- tive of that smaller nanometer scale rings present along the perforated assemblies could potentially represent hydrophobic domains, which may facilitate the adsorption and aggregation of naphthalene onto the natural particle surfaces and therefore lead to an important role of dissolved humic sub- stances in the sorption of environmental pollutants.

关键词： atomic force microscopy (AFM) dissolved humic substances morphology aggregation adsorption

Redevelopment of liftoff rates of saltating sand grains based on a simple optimization model

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Science china Earth Sciences 2010年第4期53卷 568-574页

作者： CHENG Hong & ZOU XueYong state key laboratory of Earth Surface Processes and Resource Ecology,beijing Normal university,beijing 100875,china MOE Engineering Center of Desertification and Blown-sand control,beijing Normal university,beijing 100875,china key laboratory of Environmental Change and Natural Disaster of the Ministry of Education of china,beijing Normal university,beijing 100875,china 1. state key laboratory of Earth Surface Processes and Resource Ecology Beijing Normal University Beijing 100875 China2. MOE Engineering Center of Desertification and Blown-sand Control Beijing Normal University Beijing 100875 China3. Key Laboratory of Environmental Change and Natural Disaster of the Ministry of Education of China Beijing Normal University Beijing 100875 China

This paper is a redevelopment result of liftoff rates of saltating sand grains based on our previous *** sand flow is a complex multi-phase flow because of a special two-phase gas-solid flow near ground *** extensive research on the movement of blowing sand,no model fully characterizes aeolian sand flow,and large differences often exist between simulations of aeolian sand movement and field *** key problem is a few of sufficient research on liftoff rates of saltating sand grains(also called the number of liftoff sand grains per unit time and per unit bed area).It is necessary to re-search in advance liftoff rates of saltating sand *** redeveloped liftoff rates of saltating sand grains by establishing an optimization model based on the flux of aeolian sand flow at different heights of the sampler in wind tunnel and the simulated capture of saltating sand grains by different heights of the sampler that are from different liftoff position(distance from the sampler) in order to revise previous inversion condition of liftoff rates of saltating sand *** rates increased rapidly with increasing wind *** frictional wind velocities of u=0.67,0.77,0.82,0.83,and 0.87 m s-1,liftoff rates were 3840,954502,5235114,5499407,and 7696291 sand grain s-1 m-2,*** rates could be expressed as the square of the instantaneous frictional wind velocity and a constant(0.663) that differs from the critical(threshold) frictional wind velocity at which saltation *** our results require additional experimental validation and the simple optimization model must be improved,they nonetheless provide a strong basis for future research.

关键词： liftoff rates of saltating sand grains optimization model wind tunnel two-phase gas-solid flow