Economic analysis of Japanese air pollution regulation: An optimal retirement problem under the vehicle type regulation in the NOx–particulate matter law

This paper examines the vehicle type regulation that was introduced under the Automobile Nitrogen Oxides–Particulate Matter Law to mitigate air pollution in Japanese metropolitan areas. The vehicle type regulation effectively sets the timing for vehicle retirement by initial registration year and type. However, there was no consideration of cost or efficiency in choosing the timing of retirement. We solve an optimal problem to maximize the social net benefit under the current framework of the vehicle type regulation. The analysis finds that the net benefit can more than double if the optimal retirement timing is chosen. Further, we find that even a simple alteration of the retirement timing can increase the social net benefit by 13%.     

Evaluation of factors for carrier selection in the China Pearl River delta

The efficient integration of logistics modes is critical for international cargo shipping. The local transportation connecting to the export port then plays a vital role in such integration. This paper investigates the problems of carrier selection in the China Pearl River delta area, with respect to international shipping. The analytical hierarchy process (AHP) model is constructed based on a comprehensive industrial interviews and statistical analysis. Rather than simply ranking the given alternatives, we use AHP is used to analyse the weakness and strength of impacting factors in carrier selection. The model is implemented under different types of shipper. Seven criteria are statistically summarized from the questionnaire for evaluating eight different modes. The results are useful to those liner companies serving the PRD region in relationship to port selection and fleet deployment.     

长途客车内空气质量标准评价

文章简要介绍国内长途客车标准现状,详细分析现有标准存在问题,针对相应问题提出解决方案,为标准制修订提供参考建议。     

Sampling of alternatives for route choice modeling

This paper presents a new paradigm for choice set generation in the context of route choice model estimation. We assume that the choice sets contain all paths connecting each origin–destination pair. Although this is behaviorally questionable, we make this assumption in order to avoid bias in the econometric model. These sets are in general impossible to generate explicitly. Therefore, we propose an importance sampling approach to generate subsets of paths suitable for model estimation. Using only a subset of alternatives requires the path utilities to be corrected according to the sampling protocol in order to obtain unbiased parameter estimates. We derive such a sampling correction for the proposed algorithm.Estimating models based on samples of alternatives is straightforward for some types of models, in particular the multinomial logit (MNL) model. In order to apply MNL for route choice, the utilities should also be corrected to account for the correlation using, for instance, a path size (PS) formulation. We argue that the PS attribute should be computed based on the full choice set. Again, this is not feasible in general, and we propose a new version of the PS attribute derived from the sampling protocol, called Expanded PS.Numerical results based on synthetic data show that models including a sampling correction are remarkably better than the ones that do not. Moreover, the Expanded PS shows good results and outperforms models with the original PS formulation.     

基于ADAMS的发动机曲轴系动力学仿真

建立包括柔性曲轴、活塞组、连杆组及飞轮在内的某型发动机刚柔体混合动力学仿真模型,在1 500 r/min工况下,对发动机进行刚柔体混合动力学仿真,得到了发动机的曲柄销负荷、活塞销负荷及最大动态应力等仿真结果.     

动态质量功能展开在供应商业绩改进中的应用研究

以动态质量展开为基础,建立了供应商的评价模型.通过模型结果分析,准确预测了顾客需求的趋势,并提出了有效的技术改进措施,对供应商企业业绩改进有现实的指导意义.     

严峻问题——经济、燃油或本、运力、码头运输工人联盟谈判产生了不确定性

今年关于太平洋航线有两个不确定因素，即美国进口量增长将会大大放缓，同时美国出口量会继续增加。因此，几乎所有其他的问题都是不确定的：进口量是否会增长还是会减少？航运公司是否会随着船只规模的增加，而为贸易业务分配更多运力，或者仅仅保持现有运力？他们是否能够成功增加运费以弥补成本的增长？发货人是否同意支付完全不固定的船舶燃油附加费？     

Interval estimation in the calibration of certain trip distribution models

This paper argues for interval, rather than point, estimation when calibrating some variants of the trip distribution “gravity” models. Analytic expressions are derived for the approximate asymptotic covariances of least squares and maximum likelihood estimates of the parameters in the impedance function under a variety of conditions. A comparative numerical example, and an application using migration flows, are also presented.