Transition choice probabilities and welfare analysis in random utility models with imperfect before–after correlation

Welfare in random utility models is used to be analysed on the basis of only the expectation of the compensating variation. De Palma and Kilani (De Palma, A., Kilani, K., 2011. Transition choice probabilities and welfare analysis in additive random utility models. Economic Theory 46(3), 427–454) have developed a framework for conditional welfare analysis which provides analytic expressions of transition choice probabilities and associated welfare measures. The contribution is of practical relevance in transportation because it allows to compute shares of shifters and non-shifters and attribute benefits to them in a rigorous way. In De Palma and Kilani (2011) the usual assumption of unchanged random terms before and after is made.The paper generalises the framework for conditional welfare analysis to cases of imperfect before–after association of the random terms. The joint before–after distribution of the random terms is introduced with postulated properties in terms of marginal distributions and covariance matrix. Analytic expressions, based on the probability density function and the cumulative distribution function of the joint before–after distribution, and simulation procedures for computation of the transition choice probabilities and the conditional expectations of the compensating variation are provided. Results are specialised for multinomial logit and probit. In the case without income effects, it is proved that the unconditional expectation of the compensating variation depends only on the marginal distributions.The theory is illustrated by a numerical example which refers to a multinomial logit applied to the choice of the transport mode with two specifications, one without and one with income effects. Results show that transition probabilities and conditional welfare measures are affected significantly by the assumption on the before–after correlation. The variability in the transition probabilities across transitions tends to decrease as the before–after correlation decreases. In the extreme case of independent random terms, the conditional expectations of the compensating variation tend to be close to the unconditional expectation.     

冷再生沥青混合料水稳定性试验研究

通过实验室试验,探讨乳化沥青冷再生沥青混合料的水稳定性以及水泥对其的改善效果。试验与分析显示,乳化沥青冷再生沥青混合料的冻融劈裂试验残留强度比TSR随旧沥青混凝土路面RAP材料含量的增加略有减小,约在60%左右,远低于现行《公路沥青路面施工技术规范》(JTG F40-2004)要求。水泥作为常用的辅助再生剂,还可以显著改善冷再生沥青混合料的水稳定性;添加1%水泥可以使100%RAP混合料的TSR由57%提高到77%,绝对增加20%或相对增加34%,满足规范对普通热拌沥青混合料在年降雨量>1000 mm潮湿区TSR≥75%的要求;但是,水泥剂量的再增加并不能进一步提高TSR。     

真空-堆载联合预压处理软基试验研究

该文结合试验工程资料,对真空-堆载联合预压法处理软基中有效处理范围、沉降特征、加固效果、经济技术性及工程应用中相关问题等进行了分析、评价。     

软土固结的非线性特征与沉降分析

首先以实测沉降数据为基础，采用正反演分析和时间序列分析相结合的办法，证明了一维固结非线性理论较一维固结线性理论更符合工程实际。其次，采用一维固结非线性理论对某高速公路软基的沉降固结特性进行了分析，最后提出了采用比例系数法定量地分析超载对降低工后沉降的作用，并对某高速公路软基的沉降进行了分析。     

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针对船员证后管理的现状,分析船员证后监督的重要性,探讨船舶安全检查的优势,提出运用安检优势强化船员证后监督,促使船员持续地保持适任能力。     

高铁波浪状地形路基间过渡段沉降特性与控制效果

针对深厚软土地区连续路堤路堑过渡段沉降控制,结合模糊层次分析法,采用沉降板、分层沉降管和单点沉降计3种监测技术,开展变形特性与工后沉降控制研究,并对工后沉降影响因素进行探讨。研究结果表明:根据地层特性选择地基处理方式,过渡段纵向差异沉降量较小,保证了线路平顺。各断面横向沉降路肩大于路基中心,铺轨前的横向差异沉降为4~9 mm。沉降增长速率在加载期明显变大,间歇期变小,进入恒载期后,沉降曲线逐渐变缓,虽略有回弹,但沉降逐渐趋于稳定。揭示了高速铁路软土路基沉降变形规律,并提出波浪状地形路基间过渡段工后沉降控制措施。研究结果为进一步理论研究和工程设计提供了有益的依据。     

泡沫轻质土在杭州东站软土路基地基处理中的应用

为解决铁路杭州东站站房空间受限软土路基工后沉降及填筑压实两个难题。针对场地施工作业面狭小、工况复杂和常规的加固方法不能满足工程需要的特点,经过综合比选,将泡沫轻质土这种新型材料应用于处理铁路深厚层软土路基。通过对软土地基的沉降监测,采用泡沫轻质土置换技术可以有效减小基底附加应力,能大幅减少路基工后沉降,同时,能解决狭小空间填筑压实困难。研究表明,泡沫轻质土置换加固是一种有效的软土路基处理方法,具有广阔的应用前景。     

砂桩－网复合地基2次预压沉降计算方法

京沪高速铁路昆山试验段技术升级改造,时隔5a后对原有砂桩－网复合地基进行2次预压,能否满足高速铁路工后沉降控制要求成为关键问题。分析了砂桩地基固结变形规律,利用模糊数学（Fuzzy）理论的“升半柯西分布”,建立隶属度函数描述砂桩－网复合地基从固结排水到复合地基的转化程度,提出固结度表达式,并通过实测数据验证该表达式计算精度。并对考虑土体应力历史影响的e －lgp曲线法计算2次预压沉降量进行探讨,该方法可最终实现工后沉降精确估算。     

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随着新能源汽车产销量的快速增长,宝马集团根据人力资源发展需求,为经销商提供了全岗位的人才培养和考核认证支持。对于新能源汽车售后服务技术人才培养而言,宝马集团构建的基于安全原则的分级培养体系、基于岗位需求的模块化课程和基于线上与线下融合的课前、课中、课后全方位的混合式学习模式,为我国职业院校新能源汽车运用与维修专业的人才培养和专业建设提供了优化思路。