检索结果-南通市图书馆

Progress in Natural Science:Materials International 2006年第5期16卷 464-473页

作者： WANG Jinting (Department of Mathematics, beijing jiaotong university, beijing 100044, China) Department of Mathematics Beijing Jiaotong University Beijing 100044 China

This paper concerns the reliability issues as well as queueing analysis of M/G/1 retrial queues with general retrial times and server subject to breakdowns and repairs. We assume that the server is unreliable and customers who find the server busy or down are queued in the retrial orbit in accordance with a first-come-first-served discipline. Only the customer at the head of the orbit queue is allowed for access to the server. The necessary and sufficient condition for the system to be stable is given. Using a supplementary variable method, we obtain the Laplace-Stieltjes transform of the reliability function of the server and a steady state solution for both queueing and reliability measures of interest. Some main reliability indexes, such as the availability, failure frequency, and the reliability function of the server, are obtained.

关键词： retrial queues general retrial times reliability server breakdowns and repairs.

A BATCH ARRIVAL RETRIAL QUEUE WITH STARTING FAILURES,FEEDBACK AND ADMISSION CONTROL

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Journal of Systems Science and Systems Engineering 2010年第3期19卷 306-320页

作者： Jinting WANG Peng-Feng ZHOU Department of Mathematics,School of Science,beijing jiaotong university,beijing,China Department of Mathematics School of Science Beijing Jiaotong University Beijing China

This paper is concerned with the analysis of a feedback M^[X]/G/1 retrial queue with starting failures and general retrial times. In a batch, each individual customer is subject to a control admission policy upon arrival. If the server is idle, one of the customers admitted to the system may start its service and the rest joins the retrial group, whereas all the admitted customers go to the retrial group when the server is unavailable upon arrival. An arriving customer （primary or retrial） must turn-on the server, which takes negligible time. If the server is started successfully （with a certain probability）, the customer gets service immediately. Otherwise, the repair for the server commences immediately and the customer must leave for the orbit and make a retrial at a later time. It is assumed that the customers who find the server unavailable are queued in the orbit in accordance with an FCFS discipline and only the customer at the head of the queue is allowed for access to the server. The Markov chain underlying the considered queueing system is studied and the necessary and sufficient condition for the system to be stable is presented. Explicit formulae for the stationary distribution and some performance measures of the system in steady-state are obtained. Finally, some numerical examples are presented to illustrate the influence of the parameters on several performance characteristics.

关键词： Batch arrival feedback repair retrial queue starting failure

On time-step in structural seismic response analysis under ground displacement/acceleration

在线全文

学校读者我要写书评

暂无评论

Earthquake Engineering and Engineering Vibration 2009年第3期8卷 341-347页

作者： TianYuji~+ and Yang Qingshan~(++) School of Civil Engineering,beijing jiaotong university,beijing 100044,China +Associate Professor ++Professor School of Civil Engineering Beijing Jiaotong University Beijing China

There are two models in use today to analyze structural responses when subjected to earthquake ground motions, the Displacement Input Model （DIM） and the Acceleration Input Model （AIM）. The time steps used in direct integration methods for these models are analyzed to examine the suitability of DIM. Numerical results are presented and show that the time-step for DIM is about the same as for AIM, and achieves the same accuracy. This is contrary to previous research that reported that there are several sources of numerical errors associated with the direct application of earthquake displacement loading, and a very small time step is required to define the displacement record and to integrate the dynamic equilibrium equation. It is shown in this paper that DIM is as accurate and suitable as, if not more than, AIM for analyzing the response of a structure to uniformly distributed and spatially varying ground motions.

关键词： integration time step multi-supported structure displacement input model acceleration input model spatially varying ground motions

Reduced analysis and confirmatory research on co-adaptability theoretical solution to conflicting events in construction engineering projects

在线全文

学校读者我要写书评

暂无评论

Science China(Technological Sciences) 2010年第2期53卷 480-485页

作者： HOU XueLiang1 , LU Mei2 & WANG Kai3 1 School of Business Administration, North China Electric Power university, beijing 102206, China 2 Department of Construction Management, Tsinghua university, beijing 100084, China 3 College of Management, beijing jiaotong university, beijing 100084, China School of Business Administration North China Electric Power University Beijing China Department of Construction Management Tsinghua University Beijing China College of Management Beijing Jiaotong University Beijing China

The co-adaptability theoretical solution to conflicting events in construction engineering projects has three problems. First, the transformation of constraint conditions of theoretical solution is very difficult in practical engineering applications; second, some coefficients are difficult to be determined; third, there are overfull circular arithmetic operations involved in it. To resolve these problems, a new method to reduce the theoretical solution complications is proposed. By analyzing the operating mechanism of theoretical solution model, redundancies in the theoretical solution can be eliminated, and the ISM mapping with the co-adaptability solution can be set up. Based on this approach, a procedure to solve practical conflicting events in construction projects is established by replacing characteristic variables with mathematic variables. The research results show that the procedure can replace the co-adaptability theoretical solution effectively and solve practical conflicting events in construction projects.

关键词： construction project conflict theoretical solution reduced analysis ISM confirmatory research

A new seismic isolation system and its feasibility study

在线全文

学校读者我要写书评

暂无评论

Earthquake Engineering and Engineering Vibration 2010年第1期9卷 75-82页

作者： Jia Gaofeng~+ and Shi Zhifei~(++) School of Civil Engineering,beijing jiaotong university,beijing 100044,China Graduated Student ++ Professor School of Civil Engineering Beijing Jiaotong University Beijing China

This paper introduces a new seismic isolation system called a periodic foundation （PF）, where inclusions are periodically arranged. The PF is different from traditional base isolation in that it causes a fundamental frequency shift in the structure, thus reducing its response and generating a frequency gap. If the frequency contents of a seismic wave fall into the gap, it can not propagate in the foundation. Thus, it will exert no influence on the structure above. A systematic study of the band of frequency gap for a 2D PF is conducted. The influence of physical and geometrical parameters such as density and elastic modulus as well as filling fraction of the PF and its materials on the band of frequency gap are investigated, and a design with a frequency gap as low as 2.49-3.72 Hz is achieved. This band of frequency gap corresponds well to the design spectra in earthquake engineering. Numerical simulations of a six-story frame structure with different foundations demonstrate that a proposed PF can greatly reduce the seismic response of an isolated structure. This investigation shows that PFs have great potential in future applications of seismic isolation technology.

关键词： seismic isolation periodic foundation band of frequency gap

Surface embeddability of graphs via homology

在线全文

学校读者我要写书评

暂无评论

Science China Mathematics 2010年第11期53卷 2889-2892页

作者： LIU Yan PeiInstitute of Mathematics, beijing jiaotong university, beijing 100044, China Institute of Mathematics Beijing Jiaotong University Beijing China

This paper presents a characterization of the embeddability on a surface of genus arbitrarily given for a graph. Its specific case for the surface of genus zero leads to the famous planarity theorems given independent... 详细信息

关键词： surface graph embedding duality homology

A new method for counting trees with vertex partition

在线全文

学校读者我要写书评

暂无评论

Science China Mathematics 2008年第11期51卷 2000-2004页

作者： LIU YanPei Institute of Mathematics, beijing jiaotong university, beijing 100044, China Institute of Mathematics Beijing Jiaotong University Beijing China

A direct and elementary method is provided in this paper for counting trees with vertex partition instead of recursion, generating function, functional equation, Lagrange inversion, and matrix methods used before.

关键词： tree planted tree joint tree model vertex partition code 05C30 05C10

Urban expressway traffic state forecasting based on multimode maximum entropy model

在线全文

学校读者我要写书评

暂无评论

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 State Key Laboratory of Rail Traffic Control and Safety Beijing Jiaotong University Beijing China School of Traffic and Transportation Beijing Jiaotong University Beijing China beijing Traffic Management Bureau Beijing 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

Techniques for searching first integrals by Lie group and application to gyroscope system

在线全文

学校读者我要写书评

暂无评论

Science China Mathematics 2005年第8期48卷 1135-1143页

作者： HU Yanxia & GUAn Keying Department of Mathematics, School of Science, beijing jiaotong university, beijing 100044, China Department of Mathematics School of Science Beijing Jiaotong University Beijing China

In the paper, the methods of finding first integrals of an autonomous system using one-parameter Lie groups are discussed. A class of nontrivial one-parameter Lie groups admitted by the classical gyroscope system is found, and based on the properties of first integral determined by the one-parameter Lie group, the fourth first integral of the gyroscope system in Euler case, Lagrange case and Kovalevskaya case can be obtained in a uniform idea. An error on the fourth first integral in general Kovalevskaya case (A=B=2C,zG=0), which appeared in literature is found and corrected.

关键词： one-parameter Lie group first integral gyroscope system