National United Engineering Laboratory of Integrated and Intelligent Transportation

Chengdu, China

National United Engineering Laboratory of Integrated and Intelligent Transportation

Chengdu, China
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Zhu J.,Southwest Jiaotong University | Zhu J.,National University of Singapore | Hu L.,Southwest Jiaotong University | Hu L.,National University of Singapore | And 3 more authors.
European Journal of Operational Research | Year: 2017

Width is crucial to the performance of circulation network in urban rail transit station. However, poor performance has been observed in most existing circulation systems. In fact, randomness and state-dependence exist in circulation network where blocking and feedback cannot be ignored. In this paper, we develop a PH(n)/PH(n)/. C/. C state-dependent queuing network model with an analytical solution. This model describes the random and state-dependent arrival interval as well as service time by phase-type distribution. Feedback is also taken into account. The existing M/M(n)/. C/. C is a special case of the proposed PH(n)/PH(n)/. C/. C queuing network model, and the existing M/G(n)/. C/. C and D/D/1/. C models can be approximated by the proposed network model. Then we present a programming formulation for circulation network design with blocking probability control based on the queuing network model. Finally, we illustrate the applicability of the proposed design method by comparing it with the existing design methods. The results show that: 1) the blocking probability is quite small and evenly distributed in the network designed by the new method, while much bigger and fluctuating blocking probabilities exist in networks designed by the other two methods; 2) other performance measures, like area per passenger, dwell time and throughput, are also considerably improved in the new method; 3) performance measures of the proposed method enjoy high performance-cost elasticity compared with the other two methods. An interesting insight is also obtained that the squared coefficient of variation for arrival interval plays an important role in determining the optimal width for circulation network. © 2017 Elsevier B.V.


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.


Zhang K.,National United Engineering Laboratory of Integrated and Intelligent Transportation | Shi P.,Southwest Jiaotong University
ICTE 2015 - Proceedings of the 5th International Conference on Transportation Engineering | Year: 2015

In order to solve the driving safety problem caused by the complicated terrain conditions and the changeable climate for mountainous freeway, it is necessary to construct assess index system to improve transportation security for mountainous freeway. The method used in this paper is: by taking the advantage of diagnosing and inferring the uncertainty of the knowledge of Bayesian network, we put forward a transportation security assessment model for mountainous freeway based on Netica. We use the model to evaluate a practical mountainous freeway and the result shows: The probability of the freeway section to keep in a safe state is 71.5%, and the safety grade of the road section of mountains freeway is 2. © ASCE.


Huang L.,Southwest Jiaotong University | Shuai B.,National United Engineering Laboratory of Integrated and Intelligent Transportation
ICTE 2015 - Proceedings of the 5th International Conference on Transportation Engineering | Year: 2015

In order to provide different result to the decision makers with different risk preference of hazardous materials transportation adaptively, we bring conditional value-at-risk (CVaR) modal into the risk assessment question of multimodal transportation of hazardous materials. First we analyzed the entire process of multimodal transportation of hazardous materials systematically, and then we built the CVaR model, and tried to change the traditional model into a new optimization model. According to the characteristics of the model, we designed an algorithm based on node-arc. A numerical example shown that CVaR model of different confidence level could be solved by the algorithm quickly and efficiently. The results show that the CVaR model could cover risk preference from risk-neutral to risk-averse, and it is a more proper and flexible risk measure for multimodal transport of hazardous materials decision making. © ASCE.


Zhang K.,National United Engineering Laboratory of Integrated and Intelligent Transportation | Wang R.,Southwest Jiaotong University
ICTE 2015 - Proceedings of the 5th International Conference on Transportation Engineering | Year: 2015

In order to study the unique accident characteristics of mountain roads to guarantee safety. Through careful investigation and information search on mountain roads and on the basis of a large number of data and cases of actual accidents, this paper summarized the main features of accidents in mountainous areas. According to the core idea of intrinsic safety, more attention should be paid to the design stage of road construction in mountain areas. Using both qualitative and quantitative methods, this paper sums up the main factors that influence the safety of mountain roads, they are road geometry, road condition and unique road environment in mountain areas. On the basis of the three factors, this paper proposes the principles and methods of dangerous section of governance. Through various analysis and comparison, this paper provides a more reasonable method of identifying black spots. The research results show that: The main reason of road accidents is a continuous curve and stadia, the tunnel without lighting equipment and water seepage inside the tunnel after earthquake are the factors that lead to accident, and the existence of the hidden dangers of accidents are mainly caused by the loosening mountain rocks and the lack of Kanawha rail. © ASCE.


Shi H.,Southwest Jiaotong University | Shi H.,National United Engineering Laboratory of Integrated and Intelligent Transportation
ICTE 2015 - Proceedings of the 5th International Conference on Transportation Engineering | Year: 2015

Railway information sharing platform is the key technology to realize the railway information systems connectivity, integration and optimization of all kinds of information resource in railway companies. Security technologies of railway information sharing platform are the foundation of the long-Term stable operation of the platform. Through analysis of security requirements and technical characteristics, the key security technologies are pointed out, mainly including access control technology, single sign-on technology, authentication technology and unified security center technology, etc. The security technologies laid a foundation for safety management implementation of the platform. © ASCE.


Sun F.,Southwest Jiaotong University | Zhang K.,Southwest Jiaotong University | Zhang K.,National United Engineering Laboratory of Integrated and Intelligent Transportation
ICTE 2015 - Proceedings of the 5th International Conference on Transportation Engineering | Year: 2015

The lightweight design of vehicle has become an important research topic of green transportation because of many advantages with high security, energy-saving, emission reduction and so forth in the environment of the green traffic. In a premise of clear understanding of lightweight vehicles, the article discussed the factors influencing lightweight vehicle design from the two aspects of design cost and vehicle energy consumption. The research results show that: through the use of green welding forming technology, it can effectively reduce the vehicle quality and the energy consumption. By using aluminum alloy, weathering steel and composite material composite structure design, not only it can satisfy the requirements of the integration of the vehicle structure, but also can reduce the vehicle weight to realize the balancing of benefits and costs so as to provide a good direction for the green traffic to build a resource conserving and environment friendly society. © ASCE.


Zhang R.,Southwest Jiaotong University | Zhang R.,National United Engineering Laboratory of Integrated and Intelligent Transportation
ICTE 2015 - Proceedings of the 5th International Conference on Transportation Engineering | Year: 2015

Today, strategic alliance of global logistics is considered as a new device to raise business profit and manage contemporary logistics resource effectively. This paper will give an idea of global logistics strategic alliance in general and point out its roles in contemporary logistics and supply chain. © ASCE.


Zhang K.,National United Engineering Laboratory of Integrated and Intelligent Transportation | Qiu Q.,Southwest Jiaotong University
ICTE 2015 - Proceedings of the 5th International Conference on Transportation Engineering | Year: 2015

As to improve road traffic safety and traffic efficiency, this paper focused on the study of highway traffic safety facilities. By investigating the currently basic application of highway traffic safety facilities, combining with the traffic accidents statistics and the setting regulation of highway traffic safety facilities, the problems of each kind of safety facilities were described in detail. Result shows that the main problems existing is caused by the lack of traffic safety facilities and unreasonable traffic safety facilities' setting. Finally, this paper analyses the causes of the problems from the planning, design, construction and maintenance management of highway safety facilities and puts forward the improvement measures. © ASCE.


Yang D.,Southwest Jiaotong University | Yang D.,National United Engineering Laboratory of Integrated and Intelligent Transportation | Qiu X.,Southwest Jiaotong University | Qiu X.,National United Engineering Laboratory of Integrated and Intelligent Transportation | And 3 more authors.
Physica A: Statistical Mechanics and its Applications | Year: 2015

To better understand the characteristics of car-truck heterogeneous traffic flow that is very common on freeway, a cellular automata-based traffic flow model is proposed for single lane traffic in this paper. The proposed model discriminates the four types of car-truck following combination, car-following-car (CC), car-following-truck (CT), truck-following-car (TC) and truck-following-truck (TT). The four combinations are considered in terms of the safety distance, reaction time and randomization probability. The parameter values in the proposed model are derived from NGSIM data. Simulations are conducted based on the new model and some new conclusions about the characteristics of the car-truck traffic flow are drawn. First, in the density range of (23-36) vehs/km, the fundamental diagram mainly depends on the car-truck following combination, especially, on the proportion of CC combination. In this range, the fundamental diagram curves with the same proportion of CC gather into a cluster, and the flow rate increases with the increment of the proportion of CC for the same traffic density. Second, traffic congestion can be effectively reduced up to 6.3% by increasing the proportion of TC or CT combination. This finding provides a possible way to alleviate traffic congestion on freeway. Third, reducing randomization probability of the four combinations can effectively increase traffic capacity and alleviate traffic congestion. © 2015 Elsevier B.V. All rights reserved.

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