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821.
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823.
时间触发CAN--TTCAN 总被引:5,自引:0,他引:5
随着车上网络技术的深入应用,ISO11898-1定义的标准CAN逐渐显示了在实时性方面的不足。Bosch公司开发了建立在标准CAN基础上的支持时间触发的CAN高层协议——时间触发CAN。本文详细分析时间触发CAN——TTCAN的同步调度工作机制,并比较了CAN和其他时间触发方式的车上网络协议Byteflight和TTP/C各自的优缺点。 相似文献
824.
The Influences of the Built Environment and Residential Self-Selection on Pedestrian Behavior: Evidence from Austin, TX 总被引:3,自引:0,他引:3
Pedestrian travel offers a wide range of benefits to both individuals and society. Planners and public health officials alike
have been promoting policies that improve the quality of the built environment for pedestrians: mixed land uses, interconnected
street networks, sidewalks and other facilities. Whether such policies will prove effective remains open to debate. Two issues
in particular need further attention. First, the impact of the built environment on pedestrian behavior may depend on the
purpose of the trip, whether for utilitarian or recreational purposes. Second, the connection between the built environment
and pedestrian behavior may be more a matter of residential location choice than of travel choice. This study aims to provide
new evidence on both questions. Using 1368 respondents to a 1995 survey conducted in six neighborhoods in Austin, TX, two
separate negative binomial models were estimated for the frequencies of strolling trips and pedestrian shopping trips within
neighborhoods. We found that although residential self-selection impacts both types of trips, it is the most important factor
explaining walking to a destination (i.e. for shopping). After accounting for self-selection, neighborhood characteristics
(especially perceptions of these characteristics) impact strolling frequency, while characteristics of local commercial areas
are important in facilitating shopping trips. 相似文献
825.
Empirical analysis of transportation investment
and economic development at state, county and municipality levels 总被引:4,自引:0,他引:4
Numerous studies have found positive correlation between transportation infrastructure investment and economic development. Basically these studies use a conventional production function model augmented by a public capital input, mainly highways, rail and other transportation facilities. While the range of the measured economic growth effects varies widely among studies, the positive elasticity between transportation investment and economic development is now commonly accepted. Still a major puzzling issue is that the magnitude of the measured effect seems to decline significantly as the econometric model is further refined, mainly with regard to space and time lags. That is, the use of national or state data produces elasticity results, which are much larger than when using county or municipality data. Similarly, when we introduce into the econometric model a lag between the times when the transportation investments are made and when the economic benefits transpire, the measured elasticities decline with the size of the lag. Thus, the main objective of this paper is to investigate these issues analytically and empirically and provide a plausible explanation. We do so by using alternative econometric models, applying them to a database, which is composed of longitudinal state, county and municipality observations from 1990 to 2000. The key result is that transportation investments produce strong spillover effects relative to space and time. Unless these factors are properly accounted for many reported empirical results are likely to be overly biased, with important policy implications. 相似文献
826.
交通网络最短路权矩阵的迭代算法 总被引:2,自引:0,他引:2
介绍了求解交通网络最短路权矩阵的3种迭代算法,从迭代思路、时间复杂度、程序可读性等方面进行了比较,指出各算法的异同点以及联系,最后通过一个具体网络模拟了各算法的迭代过程. 相似文献
827.
The empirical valuation of travel time savings is a derivative of the ratio of parameter estimates in a discrete choice model. The most common formulation (multinomial logit) imposes strong restrictions on the profile of the unobserved influences on choice as represented by the random component of a preference function. As we progress our ability to relax these restrictions we open up opportunities to benchmark the values derived from simple (albeit relatively restrictive) models. In this paper we contrast the values of travel time savings derived from multinomial logit and alternative specifications of mixed (or random parameter) logit models. The empirical setting is urban car commuting in six locations in New Zealand. The evidence suggests that less restrictive choice model specifications tend to produce higher estimates of values of time savings compared to the multinomial logit model; however the degree of under-estimation of multinomial logit remains quite variable, depending on the context. 相似文献
828.
829.
830.
车头间距分布规律的研究 总被引:7,自引:1,他引:6
以我国混合车流作为高等级公路交通流的基本构成,分析了混合车流车型跟驶序列组合的概率;采用计算机模拟手段,得到了车头时距阈值与速度关系、不同跟车序列最小车头间距、车头间距与随机度关系和车头间距与流量关系;并通过随机度参数将微观和宏观参数整合为一体。 相似文献