The unmet travel needs of the older population: a review of the literature

Unmet travel needs can be defined as trips and activities that people need or would like to do more, but for a variety of reasons they are prevented from doing so. This paper provides a critical evaluation of the literature focused on unmet travel needs, with the aim of assessing the scope of existing studies on this topic and better understanding the full context of older people’s mobility. This narrative review identifies how travel needs in later life have been assessed, and the barriers that affect the ability of older people to fulfil these needs. Due to the heterogeneity of older people and differences in research approaches, the analysis of the literature is not conclusive in terms of identifying the real impact of the analysed variables and measures on unrealised mobility. Nevertheless, of the studies analysed, on average at least one-third of older people report unmet travel needs. This situation was found to worsen with age, and women were reported to be more affected than men. The pursuit of leisure, and in particular visiting friends and family, was found to be the activity most associated with unmet travel needs.     

Integrated imputation of activity-travel diaries incorporating the measurement of uncertainty

Procedures to transform GPS tracks into activity-travel diaries have been increasingly addressed due to their potential benefit to replace traditional methods used in travel surveys. Existing approaches for data annotation however are not sufficiently accurate, which normally involves a prompted recall survey for data validation. Imputation algorithms for transportation mode detection seem to be largely dependent on speed-related features, which may blur the quality of classification results, especially with transportation modes having similar speeds. Therefore, in this paper we propose an enhanced integrated imputation approach by incorporating the critical indicators related to trip patterns, reflecting the effects of uncertain travel environments, including bus stops and speed percentiles. A two-step procedure which embeds a segmentation model and a transportation mode inference model is designed and examined based on purified prompted recall data collected in a large-scale travel survey. Results show the superior performance of the proposed approach, where the overall accuracy at trip level reaches 93.2% and 88.1% for training and surveyed data, respectively.     

一个结合库存策略的物流选址模型

通过对最优库存策略的研究,在总需求一定的情况下,得出总库存费用与配送中心数目的平方根模拟表达式,并进一步提出考虑库存成本的选址模型。克服了以往物流选址模型中忽略库存成本这一主要因素的缺陷,使配送中心选址决策进一步完善。在给出了遗传算法的基础上,结合实际情况对模型及其算法予以简化使之具有实用性。     

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奥运期间小汽车限行政策的实施,有效缓解了北京道路交通拥堵。本文通过措施实施前后收集的居民入户调查数据,定量分析了限行措施对居民出行特征的影响,研究发现：限行政策实施后,居民总体出行率由1.88次/日降低到1.70次/日,上下学、接送人和工作外出等出行比例明显降低;私人机动车出行强度降低0.07次/（天&;#8226;辆）,乘载率提高0.10人/车;公务车出行强度增加0.70次/（天&;#8226;辆）,乘载率提高0.32人/车;地铁、公交和小汽车出行时耗分别缩短了12 min,8 min和8 min。     

我国开放式基金投资者流动性需求影响因素研究

我国的开放式基金在迅速发展的同时也经历了大规模的赎回,而基金投资者的流动性需求是导致赎回行为的主要原因.本文运用2004年和2005年开放式基金的季度数据,研究了不同类型开放式基金投资者流动性需求的影响因素.研究表明,投资者流动性需求受多种因素的影响,并且不同类型基金投资者流动性需求的影响因素也是有差异的.     

需求价格弹性在制定商用车销售策略上的应用

根据管理经济学关于需求价格弹性的概念,商用车作为一种商品有其自身的需求价格弹性,并且不同车型、不同用途、不同用户会对需求价格弹性有直接的影响。因此研究不同车型、用途的商用车产品的需求价格弹性对东风商用车公司在商品规划、开发、定价、收益确定及销售市场上判断自己的价格策略和技术成本策略具有重要意义。     

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传统的四步骤模型中的出行生成模型是预测研究范围内每个交通小区的出行发生次数和出行吸引次数，直接将居民的出行次数简单的按交通小区进行集计处理，并没有充分考虑每个人的出行次数，难以反映个人和家庭的社会经济等因素对居民个人出行次数的影响。本文根据2003年吉林省长春市居民出行调查数据，利用非集计模型建立居民个人的出行次数选择模型，并应用相关统计软件对模型进行标定，进而分析居民个人的出行次数，从而求得居民个人出行次数的期望值，初步尝试探索非集计模型和四步骤模型的综合应用问题。     

基于车头时距与行程时间的排队长度算法

基于电子警察过车数据,分析该周期内车道通行车辆的车头时距变化规律,提出该周期车道排队长度值的实时计算方法。针对多次排队、绿波协调情况,结合通行车辆的行程时间对结果进行修正,得到该周期车道最大车辆排队长度值。通过桐乡市庆丰路实时监控视频对比计算结果,证明本算法具有较高准确性。算法便于工程实践,可为信号配时优化提供数据支撑。     

内河船舶航行香港航线防止空气污染的检验与管理

内河船舶航行香港航线,应满足香港《商船（防止空气污染）规例》的要求,并持有防止空气污染证书。本文结合香港规例、内河船检法规及中国海事局文件要求,按照新船与现有船舶进行区分,介绍了航行香港的内河船舶防止空气污染方面的检验要求,并提出相应的管理建议。关键词：内河船舶防止空气污染检验要求