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Research on the Effects of Train Operation Mode for Vehicle Energy Consumption
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作者 CHANG Zhenya LIU Zhigang LI Lanpeng 《International English Education Research》 2017年第4期9-12,共4页
The research background is based on great consumption of urban rail transit energy, through summarizing the research of scholars at home and abroad, the comprehensive research including train operation pattern, the tr... The research background is based on great consumption of urban rail transit energy, through summarizing the research of scholars at home and abroad, the comprehensive research including train operation pattern, the train traction characteristics and optimization design of integrated research has carried out in this paper, by using OPENTRACK software simulation to verify the optimization results according to different line features finally. The aim of this paper is to explore ways and methods of traction strategy optimization under the condition of trains timing energy saving. The main research contents of this paper are based on the research status at home and abroad, first of all, the different operating modes of the train running on the line are analysed, including the time saving mode, the energy saving mode and timing energy saving mode, and quantitative analysed the influence of different operation modes on vehicle energy consumption. The influence factors and traction calculation method of energy consumption of train running are studied. Firstly, the factors that affect the energy consumption of the train are analysed, including the basic facilities and transport organization mode. On the basis of this, the train load and running status of the train are analysed, and the model of the train movement and energy consumption are calculated. The OPENTRACK software is used to establish the actual circuit model, and the simulation is verified. The results show that the reasonable operation mode of the train operation mode can greatly reduce the energy consumption. 展开更多
关键词 Train Operation mode timing Energy Saving mode Energy Consumption Ant Colony Algorithm SIMULATION
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Spatial-temporal Characteristics and Factors Influencing Commuting Activities of Middle-class Residents in Guangzhou City, China 被引量:8
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作者 DAI Dandan ZHOU Chunshan YE Changdong 《Chinese Geographical Science》 SCIE CSCD 2016年第3期410-428,共19页
The middle class in metropolitan Chinese cities has become an important social group. With the rapid development of urbanization and constant advancement of suburbanization, the middle class has increasingly come to i... The middle class in metropolitan Chinese cities has become an important social group. With the rapid development of urbanization and constant advancement of suburbanization, the middle class has increasingly come to influence city traffic. Research into middle-class commuting activities thus has practical significance for improving traffic congestion and reducing the commuting burden in metropolitan cities. Based on a dataset formed by 816 completed surveys, this paper analyzes the commuting mode, time and distance of middle-class residents in Guangzhou City using the descriptive statistical method. The results indicate that private cars are the main commuting mode, followed by public transport. Meanwhile, middle-class residents mainly undertake medium-short time and medium-short distance commuting. The study subsequently uses multilevel logistic regression and multiple linear regression models to analyze the factors that influence commuting mode choice, time and distance. The gender, age, number of family cars, housing source and jobs-housing balance are the most important factors influencing commuting mode choice; housing, population density, jobs-housing balance and commuting mode significantly affect commuting time; and transport accessibility, jobs-housing balance and commuting mode are the notable factors affecting commuting distance. Finally, this paper analyzes what is affecting the commuting activities of middle-class residents and determines the differences in commuting activity characteristics and influence factors between middle-class and ordinary residents. Policy suggestions to improve urban planning and urban management are also proposed. 展开更多
关键词 middle-class residents commuting mode commuting time commuting distance influencing factors Guangzhou City China
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Dynamic Stability Analysis of Linear Time-varying Systems via an Extended Modal Identification Approach 被引量:2
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作者 Zhisai MA Li LIU +3 位作者 Sida ZHOU Frank NAETS Ward HEYLEN Wim DESMET 《Chinese Journal of Mechanical Engineering》 SCIE EI CAS CSCD 2017年第2期459-471,共13页
The problem of linear time-varying(LTV) system modal analysis is considered based on time-dependent state space representations, as classical modal analysis of linear time-invariant systems and current LTV system mo... The problem of linear time-varying(LTV) system modal analysis is considered based on time-dependent state space representations, as classical modal analysis of linear time-invariant systems and current LTV system modal analysis under the "frozen-time" assumption are not able to determine the dynamic stability of LTV systems. Time-dependent state space representations of LTV systems are first introduced, and the corresponding modal analysis theories are subsequently presented via a stabilitypreserving state transformation. The time-varying modes of LTV systems are extended in terms of uniqueness, and are further interpreted to determine the system's stability. An extended modal identification is proposed to estimate the time-varying modes, consisting of the estimation of the state transition matrix via a subspace-based method and the extraction of the time-varying modes by the QR decomposition. The proposed approach is numerically validated by three numerical cases, and is experimentally validated by a coupled moving-mass simply supported beam exper- imental case. The proposed approach is capable of accurately estimating the time-varying modes, and provides anew way to determine the dynamic stability of LTV systems by using the estimated time-varying modes. 展开更多
关键词 Linear time·varying systems · Extended modal identification · Dynamic stability analysis · Time·varying modes
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Receding horizon H_∞ control for discrete-time Markovian jump linear systems
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作者 Jiwei Wen Fei Liu 《Journal of Systems Engineering and Electronics》 SCIE EI CSCD 2011年第2期292-299,共8页
Receding horizon H∞ control scheme which can deal with both the H∞ disturbance attenuation and mean square stability is proposed for a class of discrete-time Markovian jump linear systems when minimizing a given qua... Receding horizon H∞ control scheme which can deal with both the H∞ disturbance attenuation and mean square stability is proposed for a class of discrete-time Markovian jump linear systems when minimizing a given quadratic performance criteria. First, a control law is established for jump systems based on pontryagin’s minimum principle and it can be constructed through numerical solution of iterative equations. The aim of this control strategy is to obtain an optimal control which can minimize the cost function under the worst disturbance at every sampling time. Due to the difficulty of the assurance of stability, then the above mentioned approach is improved by determining terminal weighting matrix which satisfies cost monotonicity condition. The control move which is calculated by using this type of terminal weighting matrix as boundary condition naturally guarantees the mean square stability of the closed-loop system. A sufficient condition for the existence of the terminal weighting matrix is presented in linear matrix inequality (LMI) form which can be solved efficiently by available software toolbox. Finally, a numerical example is given to illustrate the feasibility and effectiveness of the proposed method. 展开更多
关键词 Marker jump linear systems receding horizon H∞ control mean square stability terminal weighting matrix pontrya-gin's minimum principle current time jump mode.
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Numerical Calculation Methods for Wavemaking Response Induced by Explosion in Harbour
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作者 Li Dejun , Shen Guoguang , Wang Rixin Cheng Hong Professor, Dept. of Ocean and Architecture Engineering, Tianjin University, Tianjin 300072 Lecturer, Dept. of Ocean and Architecture Engineering, Tianjin University, Tianjin 300072 Engineer, Naval Research Centre, P. L. A. of China, Beijing 100055 《China Ocean Engineering》 SCIE EI 1995年第4期355-364,共10页
Using the axial symmetry results of marker and cell (MAC) method as initial value in this paper, two numerical calculating methods are presented for the late wavemaking response induced by explosion in harbour. One of... Using the axial symmetry results of marker and cell (MAC) method as initial value in this paper, two numerical calculating methods are presented for the late wavemaking response induced by explosion in harbour. One of the methods is the superposition method of the vibration mode based on fluid slosh in container. Another one is the joining method of the MAC results with the shallow wave theory calculation in time domain. As a practical example, it is conducted to the numerical calculation about 1000 ton TNT equivalent explosion within touch of water surface. The results show that it can be rationally described with the methods to the wavemaking progress and character. The numerical results are identical with the observed scene on the spot experiment. The methods are simple and applicable in the engineering design. 展开更多
关键词 wavemaking response induced by explosion MAC method superposition method of vibration mode ' joining method in time domain shallow wave theory
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Robust Nonsingular Fixed Time Terminal Sliding Mode Control for Atmospheric Pollution Detection Lidar Scanning Mechanism
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作者 KANG Yu YANG Yuxiao +2 位作者 CHEN Cai LüWenjun ZHAO Yunbo 《Journal of Systems Science & Complexity》 SCIE EI CSCD 2023年第2期500-523,共24页
A robust nonsingular fixed time terminal sliding mode control scheme with a time delay disturbance observer is proposed for atmospheric pollution detection lidar scanning mechanism(APDL-SM)system.Distinguished from th... A robust nonsingular fixed time terminal sliding mode control scheme with a time delay disturbance observer is proposed for atmospheric pollution detection lidar scanning mechanism(APDL-SM)system.Distinguished from the conventional terminal sliding mode control methods,the authors design a novel fixed-time terminal sliding surface,the convergence time of sliding mode phase of which has a constant upper bound that is designable by adjusting only one parameter.Moreover,in order to overcome the problem of unknown upper bound of lumped uncertainty including model uncertainty,friction effect and external disturbances from the port environment,the authors propose a time delay disturbance observer to provide an estimation for the system lumped uncertainty.By using the Lyapunov synthesis,the explicit analysis of the convergence time upper bound are performed.Finally,simulation studies are conducted on the APDL-SM system to show the fast convergence rate and strong robustness of the proposed control scheme. 展开更多
关键词 Atmospheric pollution detection lidar fixed time terminal sliding mode time delay disturbance observer tracking control
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Arrival time fluctuation of higher order normal modes caused by solitary internal waves 被引量:5
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作者 LI Zhenglin ZHANG Renhe +1 位作者 Mohsen Badiey Jing Luo 《Chinese Journal of Acoustics》 2013年第2期133-143,共11页
The sensitivities of the normal modes arrival time to solitary internal waves (IWs) are analyzed by using the SW06 environments. Simulation results show that the arrival time of mode 1 is relatively stable. But, the... The sensitivities of the normal modes arrival time to solitary internal waves (IWs) are analyzed by using the SW06 environments. Simulation results show that the arrival time of mode 1 is relatively stable. But, there are some higher-order normal modes which arrive earlier than mode 1, and fluctuate with the appearance of solitary IWs. Explanation of the phenomenon is given based on ray theory. It is shown that, when thermocline falls down to some depths, those higher-order modes with a group of definite grazing angles mainly propagate above the thermocline and arrive earlier. 展开更多
关键词 TIME mode Arrival time fluctuation of higher order normal modes caused by solitary internal waves
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Microstructure characterization and HCF fracture mode transition for modified 9Cr-1Mo dissimilarly welded joint at different elevated temperatures 被引量:1
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作者 Chendong Shao Fenggui Lu +2 位作者 Xiongfei Wang Yuming Ding Zhuguo Li 《Journal of Materials Science & Technology》 SCIE EI CAS CSCD 2017年第12期1610-1620,共11页
The high cycle fatigue(HCF) tests of modified 9 Cr-1 Mo dissimilarly welded joint were carried out at different elevated temperatures and the fracture mechanism was systematically revealed. The fatigue strength at 1... The high cycle fatigue(HCF) tests of modified 9 Cr-1 Mo dissimilarly welded joint were carried out at different elevated temperatures and the fracture mechanism was systematically revealed. The fatigue strength at 108 cycles based on S-N curve can be estimated as a half of weld joint's yield strength for all conducted temperatures, which can be a reliable criterion in predicting the fatigue life. The results show that the inter-critical heat affected zones(IC-HAZs) of both sides are the weak zones due to their low hardness and inferior fatigue resistance property. HAZ of COST-FB2(BM2) is the weakest zone at room temperature due to the existence of numerously distributed defects and the initiation of cracks, either in the surface or interior zone, impacting a crucial effect on the fatigue life of the joint. While at elevated temperatures, fatigue life was controlled mostly by the intrusion-extrusion mechanism at the specimen surface under high stress level and subsurface non-defect fatigue crack origin(SNDFCO) from the interior material under low stress amplitude. With increasing temperature, more and more fatigue failures began to occur at the HAZ of COST-E(BM1) due to its higher susceptibility of temperature. Besides, it is found that the-ferrite in the BM1 has no harm to the HCF behavior of the joint at the conducted temperatures. 展开更多
关键词 High cycle fatigue Dissimilarly welded joint Life time Fatigue failure Fracture mode
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Numerical analysis of residence time distribution of solids in a bubbling fluidized bed based on the modified structure-based drag model 被引量:4
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作者 Zheng Zou Yunlong Zhao +4 位作者 Hu Zhao Hongzhong Li Qingshan Zhu Zhaohui Xie Yingbo Li 《Particuology》 SCIE EI CAS CSCD 2017年第3期30-38,共9页
The residence time distribution (RTD) of solids and the fluidized structure of a bubbling fluidized bed were investigated numerically using computational fluid dynamics simulations coupled with the modified structur... The residence time distribution (RTD) of solids and the fluidized structure of a bubbling fluidized bed were investigated numerically using computational fluid dynamics simulations coupled with the modified structure-based drag model. A general comparison of the simulated results with theoretical values shows reasonable agreement. As the mean residence time is increased, the RTD initial peak intensity decreases and the RTD curve tail extends farther. Numerous small peaks on the RTD curve are induced by the back- mixing and aggregation of particles, which attests to the non-uniform flow structure of the bubbling fluidized bed. The low value of t50 results in poor contact between phases, and the complete exit age of the overflow particles is much longer for back-mixed solids and those caught in dead regions. The formation of a gulf-stream flow and back-mixing for solids induces an even wider spread of RTD. 展开更多
关键词 FluidizationResidence time distribution Bubbling fiuidized bed Modified structure-based drag mode Computational fluid dynamics CFD
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A programmable gain amplifier with digitally assisted DC offset calibration for a direct-conversion WLAN receiver 被引量:1
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作者 姚小城 龚正 石寅 《Journal of Semiconductors》 EI CAS CSCD 2012年第11期90-94,共5页
This paper presents a programmable gain amplifier(PGA) circuit with a digitally assisted DC offset cancellation(DCOC) scheme for a direct conversion WLAN receiver.Implemented in a standard 0.13-μm CMOS process,th... This paper presents a programmable gain amplifier(PGA) circuit with a digitally assisted DC offset cancellation(DCOC) scheme for a direct conversion WLAN receiver.Implemented in a standard 0.13-μm CMOS process,the PGA occupies 0.39 mm2 die area and dissipates 6.5 mW power from a 1.2 V power supply.By using a single loop single digital-to-analog converter(DAC) mixed signal DC offset cancellation topology,the minimum DCOC settling time achieved is as short as 1.6μs with the PGA gain ranging from -8 to 54 dB in a 2 dB step.The DCOC loop utilizes a segmented DAC structure to lower the design complexity without sacrificing accuracy and a digital control algorithm to dynamically set the DCOC loop to fast or normal response mode,making the PGA circuit in compliance with the targeted WLAN specifications. 展开更多
关键词 direct conversion receiver digital assisted DC offset cancellation segmented current mode digital-to-analog converter settling time
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Approach and landing guidance design for reusable launch vehicle using multiple sliding surfaces technique 被引量:1
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作者 Xiangdong LIU Fengdi ZHANG +1 位作者 Zhen LI Yao ZHAO 《Chinese Journal of Aeronautics》 SCIE EI CAS CSCD 2017年第4期1582-1591,共10页
An autonomous approach and landing(A&L) guidance law is presented in this paper for landing an unpowered reusable launch vehicle(RLV) at the designated runway touchdown. Considering the full nonlinear point-mass ... An autonomous approach and landing(A&L) guidance law is presented in this paper for landing an unpowered reusable launch vehicle(RLV) at the designated runway touchdown. Considering the full nonlinear point-mass dynamics, a guidance scheme is developed in threedimensional space. In order to guarantee a successful A&L movement, the multiple sliding surfaces guidance(MSSG) technique is applied to derive the closed-loop guidance law, which stems from higher order sliding mode control theory and has advantage in the finite time reaching property.The global stability of the proposed guidance approach is proved by the Lyapunov-based method.The designed guidance law can generate new trajectories on-line without any specific requirement on off-line analysis except for the information on the boundary conditions of the A&L phase and instantaneous states of the RLV. Therefore, the designed guidance law is flexible enough to target different touchdown points on the runway and is capable of dealing with large initial condition errors resulted from the previous flight phase. Finally, simulation results show the effectiveness of the proposed guidance law in different scenarios. 展开更多
关键词 Finite time control Landing guidance Lyapunov stability Reusable launch vehicle Sliding mode control
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