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Khandker M. Nurul Habib 《Transportation》2011,38(1):123-151
The paper presents a modeling framework for dynamic activity scheduling. The modeling framework considers random utility maximization
(RUM) assumption for its components in order to capture the joint activity type, location and continuous time expenditure
choice tradeoffs over the course of the day. The dynamics of activity scheduling process are modeled by considering the history
of activity participation as well as changes in time budget availability over the day. For empirical application, the model
is estimated for weekend activity scheduling using a dataset (CHASE) collected in Toronto in 2002–2003. The data set classifies
activities into nine general categories. For the empirical model of a 24-h weekend activity scheduling, only activity type
and time expenditure choices are considered. The estimated empirical model captures many behavioral details and gives a high
degree of fit to the observed weekend scheduling patterns. Some examples of such behavioral details are the effects of time
of the day on activity type choice for scheduling and on the corresponding time expenditure; the effects of travel time requirements
on activity type choice for scheduling and on the corresponding time expenditure, etc. Among many other findings, the empirical
model reveals that on the weekend the utility of scheduling Recreational activities for later in the day and over a longer
duration of time is high. It also reveals that on the weekend, Social activity scheduling is not affected by travel time requirements,
but longer travel time requirements typically lead to longer-duration social activities. 相似文献
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A recent survey reported that many commuter-cyclists had enjoyed leisure bicycling on a regular basis prior to becoming a
commuter-cyclist. While bicycling for leisure, it is assumed that they considered various factors that led them to consider
becoming commuter-cyclists. This study began with the question of how long it would take for a leisure-cyclist to become a
commuter-cyclist, and it focused on the time that elapsed between leisure-cyclists transitioning to commuter-cycling. In order
to analyze the time frame, it was hypothesized that the probability that a leisure-cyclist would become a commuter-cyclist
at a certain time would be conditional on the duration that elapsed from the onset of leisure cycling till that time, which
represents the “snowballing” or “inertial” dynamics of duration. A robust methodology, which is known as the “hazard model,”
was adopted to accommodate such characteristics of a time period. In addition, various external covariates such as individual-specific
characteristics, variables associated with the current or previous commuting mode, supply variables regarding bicycle facilities,
and individual latent propensities were adopted to account for the duration of changes that would be generally applicable.
As a result, many useful results were derived that could be used in fomenting policies to promote cycling to work. It was
found that government should invest in establishing segregated lanes for leisure- and commuter-cyclists. It also turned out
that a long distance to work hinders a leisure-cyclist from progressing to commuter-cycling. According to the results, young
white-collar workers who live in high-rise apartments and enjoy intensive leisure-cycling in groups, are a good target toward
whom promotions for commuter-cycling should be focused. However, an unfortunate development was that, when compared with car-commuters,
it was found that transit-commuters are more likely to become commuter-cyclists. 相似文献
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石灰作为一种外加剂,用来改良膨胀土作为路基的填料,但石灰改良土击实曲线比较平缓,最优含水率较难确定,而且,在最优含水率附近压实是否就能达到较高的强度,也难以确定。针对该问题,对不同初始含水率下石灰改良膨胀土的无侧限抗压强度、CBR强度进行试验研究,并对干湿循环影响下的改良膨胀土CBR强度进行试验。结果表明:石灰改良膨胀土在初始填筑含水率稍大于击实曲线所反应的最优含水率情况下能够达到较高的强度,建议在实际施工中充分考虑初始含水率这一填筑条件对石灰改良土改良效果的影响。 相似文献
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基于自然进化原理的遗传算法是一种解决岩土工程复杂非线性问题十分有前景的方法。然而遗传算法容易陷入局部收敛,对遗传算法进行改进加入退火因子解决了这一问题。软土地基沉降受众多因素的影响,在时序上表现出复杂的非线性特征。针对木兰溪防洪工程的沉降预测问题,运用MATLAB编写模拟遗传退火算法程序进行了预测分析。计算结果与实测资料基本一致,它在全局优化、非线性优化、多参数优化等方面表现出了传统算法无法比拟的优势。 相似文献