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Elasticity analysis for high-speed railway passenger transport demand

LI Wenjun
,FU Zhuo

- , 2016,
Abstract: 旅客运输需求分析对于高速铁路规划建设和运营管理具有重要作用。采用H高铁2011-2013年的运行数据,对其客运量及相关影响因素的数据进行汇总,并将微观经济学中的“需求弹性”理论应用到高速铁路运输需求函数中,对影响客运需求的居民收入、列车旅行速度、高铁票价等因素进行弹性分析及实际测算,得到各影响因素的弹性值。根据需求弹性分析结果,对如何提高高铁运营管理水平和收益,提出应对策略建议。
The passenger demand analysis plays an important role in the high-speed railway planning and construction, as well as in the operations management. In this paper, the 2011 to 2013 operation data of H high-speed railway were taken as an example, and the data of its passenger volume and impact on factors were collected, the “elasticity of demand” theory of the microeconomics was applied to high-speed railway transport demand function for calculating and analyzing the passenger demand elasticity of these factors, such as resident income, traveling speed and ticket price. According to the results of demand elasticity analysis, several suggestions about coping strategy were put forward to improve the operations management level and profit of high-speed railway
Safety Impact of Average Speed Control in the UK  [PDF]
Harry Lahrmann, Bo Brass?e, Jonas Wibert Johansen, Jens Christian Overgaard Madsen
Journal of Transportation Technologies (JTTs) , 2016, DOI: 10.4236/jtts.2016.65028
Abstract: There is considerable safety potential in ensuring that motorists respect the speed limits. High speeds increase the number and severity of accidents. Technological development over the last 20 years has enabled the development of systems that allow automatic speed control. The first generation of automatic speed control was point-based, but in recent years a potentially more effective alternative automatic speed control method has been introduced. This method is based upon records of drivers’ average travel speed over selected sections of the road and is normally called average speed control or section control. This article discusses the different methods for automatic speed control and presents an evaluation of the safety effects of average speed control, documented through changes in speed levels and accidents before and after the implementation of average speed control at selected sites in the UK. The study demonstrates that the introduction of average speed control results in statistically significant and substantial reductions both in speed and in number of accidents. The evaluation indicates that average speed control has a higher safety effect than point-based automatic speed control.
Evaluation of Residual Stresses Induced by High Speed Milling Using an Indentation Method  [PDF]
Felipe Díaz, Claudio Mammana, Armando Guidobono
Modern Mechanical Engineering (MME) , 2012, DOI: 10.4236/mme.2012.24019

In this work, a recently developed method based on the change of distance between collinear indents is used to evaluate different states of residual stress, which were generated in samples of AA 6082-T6 and AA 7075-T6 aluminium alloys milled at high speed. One of the advantages of this method, which needs a universal measuring machine, is not requiring neither the use of specific equipment nor highly skilled operators. Also, by integrating an indentation device to the mentioned machine, the absolute error of measurement can be reduced. In results obtained in samples subjected to different cutting conditions it is observed a correlation between the stress values and the depth of cut, showing the AA 6082-T6 alloy higher susceptibility to be stressed. Furthermore, the high sensitivity of the method allowed detecting very small differences in the values reached by different normal components in the zones corresponding to climb and conventional cutting. It is important to note that these differences were similar for both evaluated alloys. Finally, the directions associated with the principal components of residual stress, where maximum local plastic stretching occurs, were found to be strongly dependent on the rolling direction prior to machining.

Analysis on the correlation between train density and travel demand intensity for high-speed railway

袁隽, ,赵烁,李丽辉,史峰
, , ZHAO Shuo, LI Lihui, SHI Feng

- , 2018,
Abstract: 为了评价高铁列车运行图是否吻合旅客的时变需求,可以针对时变需求进行客流分配,利用旅客出发时间偏差程度来评价。若未知时变需求的分布状况,则不能采用这种评价方法。本文研究如何运用高铁系统运营数据,评价列车运行图是否吻合旅客时变需求。通过定义较小时空单元及时空单元中的运输能力、客流量和客座率,来描述列车密度和出行需求及其关系。以京广高铁等线路的运营数据进行数值分析发现:合理的列车运行图在需求越高的时空区域,平均运输能力越大;在运输能力越大的时空区域,平均客座率越高。尽管数值分析中采用的是实际运量,但该特征表明列车运行图与出行需求相吻合。可以运用该特征来评价列车运行图,并适用于大规模高铁网络。
In order to evaluate whether the high-speed train diagram is in accordance with the time-dependent travel demand of passengers, the passenger flow can be assigned according to the time-dependent travel demand and the departure time deviation can be used to evaluate. However, if the distribution of the time-dependent travel demand is unknown, this evaluation method cannot be used. This paper studied the utilization of high-speed railway system operation data, to evaluate whether the high-speed train diagram is consistent with the time-dependent travel demand. By defining the smaller space-time units, the transport capacity, passenger flow and load factor in the space-time units, the train density, travel demand intensity and their relationship were described. Based on the numerical analysis of the Beijing-Guangzhou high-speed railway system operating data, it was found that the average transport capacity is lager in the space-time quadrant with higher demand in the reasonable train diagram, and the average load factor is higher in the space-time quadrant with larger transport capacity. Although the actual traffic volume data was used in the numerical analysis, the feature indicates that the train diagram corresponds to the travel demand. This feature can be used to evaluate the train diagram and apply to large-scale high-speed railway network
Application layer for high-speed narrowband power line communications for automatic demand response

- , 2016, DOI: 10.16511/j.cnki.qhdxxb.2016.21.019
Abstract: 实现电力系统自动需求响应的高速窄带电力线通信(high-speed narrowband power line communication, HNPLC)系统亟需实用、高效的应用层设计来支撑各类响应服务。该文面向自动需求响应服务, 定义了双向互动的HNPLC应用层协议架构, 并结合系统的多分类服务需求, 提出一种综合考虑数据包优先级权重、数据包传输效率和服务等待时间的基于动态优先级的应用层服务响应机制。在构建的跨层HNPLC仿真平台中验证了协议架构的合理性, 且计算机仿真结果表明, 提出的基于动态优先级的服务响应机制可明显提升HNPLC传输性能, 满足自动需求响应的服务要求。
Abstract:High-speed, narrowband power line communications (HNPLC) need effective application layers to control the power system demand response to support various services. This study defines an application architecture for an interactive HNPLC system to support automated demand response. The multi-class service demand is provided by a dynamic priority that considers the data packet priority weights, packet transmission efficiency and service waiting times. The service response mechanism, the core of the application layer, is based on the dynamic priority. The application layer is within the cross-layer HNPLC nodes in a simulated practical HNPLC network. Simulations show that the architecture is efficient and the service response mechanism improves the HNPLC performance for the automated demand response.
A Numerical Study of the Screening Effectiveness of Open Trenches for High-Speed Train-Induced Vibration  [PDF]
Chih-hung Chiang,Pei-hsun Tsai
Shock and Vibration , 2014, DOI: 10.1155/2014/489090
Abstract: This study used the 2D boundary element method in time domain to examine the screening effectiveness of open trenches on reducing vibration generated by a high-speed train. The parameters included configurations of the trench, train speed, the distance between the source and the trench, and the Poisson’s ratio of the soil. A reducing displacement level (in dB scale) was defined and used to evaluate the screening effectiveness of a wave barrier. The maximal reducing displacement level reached 25?dB when an open trench was used as a wave barrier. The depth of an open trench is a main influential parameter of screening effectiveness. The cutoff frequency of the displacement spectrum increases with decreasing trench depth. The maximal screening effectiveness occurs when the depth is 0.3-0.4 Rayleigh wavelength. Using an open trench as a wave barrier can reduce 10–25?dB of vibration amplitude at frequencies between 30 and 70?Hz. A considerable increase in screening effectiveness of the open trench was observed from 30 to 70?Hz, which matches the main frequencies of vibration induced by Taiwan High Speed Rail. The influence of trench width on screening effectiveness is nonsignificant except for frequencies from 30 to 40?Hz. Poisson’s ratio has various effects on the reduction of vibration at frequencies higher than 30?Hz. 1. Introduction High-speed trains (HSTs) have played an essential role in intercity transportation during the past decades. The weight of freight trains and the speed of passenger trains have increased. Trains passing populated areas result in ground vibration and cause disturbances to adjacent structures. Reducing vibration in nearby structures has become a crucial issue in practice. Installation of barriers (such as a row of concrete piles or steel pipe piles and open trench or infilled trench) between tracks and the structures is one solution of isolation vibration. An open trench is often used as a wave barrier causing reflection, scattering, and diffraction effects. The vibration amplitude is thus reduced on the ground surface behind the open trench. Elastomer or rubber between the ballast and subgrade, soil improvement underneath the track, and floating slab track are other effective methods to reduce vibration induced by train. A number of experimental and numerical studies [1–4] have been conducted to examine the ground vibration induced by HSTs. These studies mainly focused on the ground vibration generated by HSTs. In addition, the screening effectiveness of trenches on harmonic vibration sources generated by machine foundations
Induced Unbalance as a Method for Improving the Dynamic Stability of High-Speed Turbochargers  [PDF]
R. Gordon Kirk,Ali A. Alsaeed
International Journal of Rotating Machinery , 2011, DOI: 10.1155/2011/952869
Abstract: The high-speed diesel engine turbocharger is known to have subsynchronous vibrations for a wide speed range. The bearing fluid-film instability is the main source of the vibration. The nonlinear forces inside the bearings are causing the rotor to whirl in a limit cycle. This study presents a new method for improving the dynamic stability by inducing the turbocharger rotor unbalance in order to suppress the subsynchronous vibration. The finite-element model of the turbocharger with floating-ring bearings is numerically solved for the nonlinear time-transient response. Both compressor and turbine added unbalance are induced and the dynamic stability is computed. The turbocharger model with linearized floating-ring bearings is also solved for eigenvalues to predict the modes of instability. The linear analysis demonstrates that the forward whirling mode of the floating-ring at the compressor end also becomes unstable at the higher turbocharger speeds, in addition to the unstable forward conical and cylindrical modes. The numerical predictions are also compared to the former experimental results of a similar turbocharger. The results of the study show that the subsynchronous frequency amplitude of the dominant first mode is reduced when inducing either the compressor or the turbine unbalance at a certain level. 1. Introduction The turbocharger industry is booming recently, and there is an urgent need for new evaluations of the overall design. As the oil prices continue to rise, along with the new emissions regulations strictly enforced for the in-road as well as the off-road vehicles, the transition to turbocharged engines, and especially for diesel engines, has become irresistible. Higher power, smaller engines, reduced emissions, and overall better efficiency are the main concerns. By means of the recent development in the computational tools, a new era of the product development has emerged. Most diesel engine turbochargers incorporate floating-ring bearings that use the engine’s oil for lubrication. The high-speed turbocharger is known to have subsynchronous vibrations at high amplitudes for a wide speed range that could reach 150,000?rpm. The bearing fluid-film whirl instability is the main source of the subsynchronous vibration. The nonlinear reaction forces inside the bearings are usually causing the rotor to whirl in a limit cycle but may become large enough to cause permanent damages. Additionally, the lubrication oil may leak at higher rates through the seals into the engine or the exhaust emissions. The objective of the current research is to
The research of transfer demand calculation for High-speed railway

李丽辉, ,朱建生,史峰,单杏花
LI Lihui
, , ZHU Jiansheng, SHI Feng, SHAN Xinghua

- , 2018,
Abstract: 基于客票系统中现有的记录并未对换乘旅客进行标识,需要后期对原始数据进行深入挖掘才能获取。以往采用换乘方向的算法在处理大量数据时,耗时长,效率低。通过分析换乘旅客行为特征,提出一种比较OD最短路径距离的换乘需求统计方法。实例结果表明:该算法可以将运行效率提高近百倍,并能获得小于3%的相对误差,因此该算法用于换乘需求统计更高效。该算法在计算过程中保留了详细的车次换乘信息,因此该数据还可以用于支撑进一步的深入挖掘换乘需求特征。
To get the precise transfer demand, deeply analysis for the passenger data is needed. The algorithm based on transfer direction has low efficiency and takes longer time when dealing with big quantity data. This paper proposed an algorithm based on OD shortest distance. The experiment indicated that this algorithm can improve the performance hundreds times with relative error lower than 3%. All the transfer information for each train trip are preserved during the calculation, these data can be used to support deeply analysis for traveler’s transfer demand characteristics
Research on Dynamic Pricing Between High Speed Rail and Air Transport Under the Influence of Induced Passenger Flow  [PDF]
Zhang Xu,Luan Weixin,Cai Quande,Zhao Bingru
Information Technology Journal , 2012,
Abstract: This study first briefly describes the application of game theory and Changes arising from the combination of ticket price changes in passenger traffic to the dynamic pricing between high speed rail and air, selects Stackelberg model to describe the process of dynamic pricing process, then establishes multilayer planning dynamic pricing model between high speed rail and air transport with the thinking of bilevel programming model and calculated the constructed model ions with practical examples based on the heuristic algorithm of sensitivity analysis. With the analysis of the competition game pricing process between high speed rail and air transport, a conclusion under the influence of passenger has been drawn, that is high speed rail tends to balance ticket prices range in [38.8,39] and air transport tends to balance the ticket price range in [55.5,56]. Finally, this study systematically analyzes the passenger flow and the changes of profits in the game process of the pricing competition between high speed rail and air transport.
Laser-induced breakdown|High speed photography|Bubble oscillation|Experiment study

ZONG Si-guang,WANG Jiang-an,JIANG Xing-zhou,WANG Yu-hong,

光子学报 , 2009,
Abstract: To study the microcosmic effect,such as plasma flash,bubble oscillation and acoustic wave,optical breakdown was applied in water with Nd:YAG laser pulses.The experimental investigation of the laser-induced cavitation bubble expansion and collapse was photographed with high-Speed photography.The characteristic of laser-induced bubble was analyzed based on the bubble images.And good agreement was observed between the results of the calculations and the experimental data.
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