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该文基于大尺度路径损耗无线传播模型将高速公路场景中的车用自组织网络(VANET)建模为几何随机图,提出了VANET有效组网面积的概念,分析说明了VANET的准线性拓扑特点,并基于交通流理论关于自由流条件下的车头时距分布,推导得出了无线传输范围内至少存在k个邻居的概率计算方法.实验结果表明:该文提出的概率描述思想是一种适合计算高速公路场景中车辆网络节点度的有效方法. 相似文献
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交通生成模型是交通系统仿真的基本模型之一.传统的微观交通仿真系统中,发车模型忽略了同一路段中多车道之间的相互关系,假设车道之间相互独立的情况下直接以单车道为单位进行的发车,而在实际路网中,多个车道之间是相互影响相互作用的,文章以概率论中描述可数时间统计特性的离散型分布为工具,通过引入了在解决小样本问题中表现出全局收敛和较强泛化能力的支持向量机(SVM)进行发车模型建模,提出了基于支持向量机概率密度估计的发车模型,利用有限的支持向量对实际路口的交通流的统计分布进行回归估计,以描述具有一般意义上的多车道发车规律,得到和实际路网交通流信息更加相符的交通生成模型. 相似文献
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《洁净与空调技术》2017,(3)
为了探究隧道内车辆运动状况对竖井型城市隧道正常交通污染状况的影响,定义了表征车速和车距共同作用的间隔时间,并利用理论分析和模型试验的方法,对不同间隔时间条件下隧道和竖井速度分布和污染物浓度分布进行了研究。通过对正常交通工况下隧道的排污理论和隧道模型相似理论的分析,明确了污染物浓度分布规律与间隔时间的关联性,得到模型搭建的几何、速度以及动力相似条件。试验共设计了间隔时间分别为0.4s、0.5s、0.65s和0.8125s四组试验方案,结果表明,隧道内污染物浓度与间隔时间成反比,间隔时间越大,污染物浓度越低。因此,通过合理控制隧道内的车速和车距,能有效降低隧道内整体污染物浓度,对推动自然通风城市隧道的发展具有重要意义。 相似文献
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1 引言
LTE业务双归属方案的部署,不仅在网络安全上增加一层业务层的保护,还在承载网资源利用率上提高一倍.在eNodeB中配置双IP,当LTE基站实现LTE双归属方案后,LTE基站可以实现S1-U的双平面,对于承载网就是LTE基站从业务侧实现负荷分担,基站流量从“单车道”变成“双车道”.对于承载网的收益就是业务侧增加一层保护,更安全;对于无线网优的收益是可以让用户体验在“交通繁忙的单车道上变成双车道”,所以从长远看客户体验也是该方案的一大亮点.具体到承载网眼下看到的收益:安全加固与投资保护. 相似文献
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失效机理不变的假设检验 总被引:1,自引:0,他引:1
孙祝岭 《电子产品可靠性与环境试验》2009,27(2):1-5
文献[1]证明了寿命型随机变量情形下变差系数不变是失效机理不变的必要条件,基于这一结论,提出了检验变差系数是否相等来检验失效机理是否改变的方法。分别给出了寿命分布分别为对数正态分布、伽玛分布、weibull分布、Gumbel分布和分布自由时变差系数相等的假设检验方法。 相似文献
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《Vehicular Technology, IEEE Transactions on》1975,24(1):8-14
High capacity personal rapid transit (HCPRT) is a system concept which utilizes small, 4 to 6 passenger, vehicles at very short headways on exclusive guideway networks. The automatic operation of small vehicles at headways of 1 s or less presents a major technical problem which is amenable to a combination of design approaches. This paper explores the effect of basic parameters such as vehicle length, reaction time, emergency and failed vehicle deceleration rates, and emergency jerk rate on potential minimum operating headway. The results of this analysis are then discussed in the context of five HCPRT programs. 相似文献
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SYNCHROTRAC is a power control system that provides longitudinal control of vehicles by a unique method in which it distributes power to those vehicles. The vehicles are passive (control-wise) in that power modulation is accomplished by the vehicle's position within the traveling control section. Therefore, no on-board power modulation or communication equipment is required. The SYNCHROTRAC system can be readily employed in a wide variety of transportation applications. It is adaptable to the closed-circuit moving sidewalk applications that require slow captive vehicles operating with small headways as well as to the independently routable dual-mode application that requires fast vehicles operating with small headways. The specific vehicle design can vary to suit a particular application requiring only that the motive drive be an induction motor providing the appropriate vehicle dynamic response, i.e., voltage and frequency versus torque. 相似文献
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《Vehicular Technology, IEEE Transactions on》1979,28(1):28-35
For many years, General Railway Signal Company has supplied control systems for conventional rail transit. Headways for these systems range from minutes or hours down to as low as 75 s. In the last few years, the company has supplied control systems for people-mover applications in which minimum headways of 10-20 s have been achieved. There are many factors working together to permit achievement of this large reduction in headway. These factors are identified and evaluated for their impact on capacity. The fundamentals underlying the disparity in headway are discussed from the viewpoint of potential for increased capacity of rail transit. 相似文献
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Min Young Cho Lichtenberg A.J. Lieberman M.A. 《Vehicular Technology, IEEE Transactions on》1996,45(2):383-390
Linearized longitudinal dynamics of an automatic car-following system are analyzed to determine the minimum headway required to avoid collisions. We determine the linear controller with multiple control factors that satisfy all of the system constraints and have a minimum stopping distance. The constraints are stability, no oscillations, and the control forces remaining within a specified physical limitation of the vehicle. Numerical results show that a linear controller that satisfies all of the system constraints requires a large headway in order to avoid collisions when subject to extreme initial conditions. The results indicate the need for a nonlinear controller if collisions are to be avoided with proposed small headways 相似文献
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Fundamental system and control problems associated with proposed automated ground transportation concepts are discussed. The problem formulation provides a systematic approach toward the synthesis and techinical evaluation of a large class and future systems employing automatically controlled single-mode or dual-mode vehicles on intracity guideway networks. Important system engineerig problems--common to some degree to all proposed concepts--are defined and the associated control requirements are discussed. Basic performance criteria, the weighted average travel time and relative safety of travel, are formulated. Tradeoffs between important system parameters are identified and their relations to performance and cost are discussed. Analysis of system operation is based upon idealized models in which perfect information and control are assumed. Upper bounds on performance are thus obtained, and the main constraints are identified. The degradation of system performance resulting from random arrivals and departures is thereafter analyzed quantitatively. Finally, control problems arising from the use of short headways are discussed. The objective of the paper is to help develop a systematic approach to the design of automated transportation systems using digital computers and modern electronic communications. It concentrates on the functional system problems of relatively simple networks, which lend themselves to direct analytical approaches and which constitute a point of departure for more complex networks. 相似文献
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采用模式匹配法对波导滤波器的不连续性进行了分析,给出了模式匹配法分析波导滤波器的基本步骤,并用Matlab编写了用于计算波导滤波器S11和S21参数的模式分析程序,最后对波导对称H面膜片滤波器的S11和S21参数特性进行了计算,并对仿真结果进行了分析,总结了应用模式匹配法分析波导滤波器时应注意的一些问题。 相似文献
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The fault coverage of testing protocols using unique input/output (UIO) sequences is analyzed. UIO sequences can be efficiently employed in checking the conformance specifications of protocols by using transition testing. The test sequence is found using the rural Chinese postman tour algorithm. A comprehensive fault model is developed, and analytical expressions are given for the fault coverage. The conditions for undetectability are analyzed, and a new algorithm is proposed. Simulation results and illustrative examples are presented. Overhead issues are discussed, and significant improvements are shown for achieving 100% fault coverage. The major advantage of the proposed approach is that it provides the theoretical basis for fault coverage evaluation of protocol testing using UIO sequences 相似文献
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Tove P.A. Bohlin K. Masszi F. Norde H. Nylander J. Tiren J. Magnusson U. 《Electron Device Letters, IEEE》1988,9(1):47-49
Complementary Si MESFETs (CMES) for integrated circuits using silicon-on-sapphire are described. Not only the gate, but also the source and drain of the n-transistors and p-transistors are Schottky junctions, using very high barrier heights for the gate and low barrier heights for source and drain. Only two Schottky metals are used: one, Ir or Pt, giving a high barrier on nSi, and hence low on pSi; the other, Er or Tb, showing the opposite behavior. The basic differences between MES and MOS are pointed out and design criteria for CMES inverters using normally-off type transistors are given 相似文献
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温差电材料热导率的激光脉冲测试法 总被引:2,自引:0,他引:2
简要地介绍了热导率激光脉冲法的测量原理和实际装置,着重对该方法在半导体温差电材料热导率测试中的问题和解决途径进行了详细的讨论。 相似文献
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Ahmed M. Soliman 《Circuits, Systems, and Signal Processing》2010,29(6):1181-1191
New realizations of Chua L-C and L-R mutators using current conveyors (CCII) and inverting current conveyors (CCII) are introduced.
Two realizations are available in the literature using CCII for each of the types of L-C and L-R mutators. For the type 1a
L-R mutator three new realizations using CCII and ICCII are introduced to complete a family of four realizations. For the
type 1b L-R mutator three new realizations using CCII and ICCII are introduced to complete a family of four realizations.
For the type 2a L-C mutator fifteen new realizations using CCII and ICCII are introduced to complete a family of sixteen realizations.
For the type 2b L-C mutator fifteen new realizations using CCII and ICCII are introduced to complete a family of sixteen realizations.
For the type 2c L-C mutator eight new realizations using CCII and ICCII are introduced to complete a family of sixteen realizations.
Finally for the types 2a and 2b L-R mutator fifteen new realizations using CCII and ICCII are given for each type to complete
a family of sixteen realizations. Although this is a review paper and is partially tutorial it includes many new realizations
of L-C and L-R mutators. 相似文献