关于城市道路规划设计几个问题的探讨

本文主要论述城市道路规划设计应正确认识道路环境、道路功能、重视道路等级与里程长度以及路口与路段通行能力的协调配合。     

内燃机泄放失效机油存在的问题及解决方法

指出了内燃机油底壳上放油螺丝在使用中存在的问题 ,分析由此而引起的后果 ,提出了排放失效机油过程中所需达到的要求 ,介绍了内燃机机油专用放油阀门     

孕妇血清铜值与胎盘功能的关系

用火焰原子吸收法测定了孕28～40周正常孕妇83例,孕37～40周重度妊娠高血压综合征及41周以上妊娠妇女42例的血清铜值,并与同期尿E/C比值及新生儿Apgar评分相比较,结果提示:孕妇血清铜值在40周前随孕周的增长而增高。41周以上妊娠,重度妊高征血清铜值偏低。当尿E/C比值<10及Apgar评分≤7分时,孕妇血清铜值低,提示孕晚期母亲血清铜值可作为判断胎盘功能的辅助指标。     

测定游离甲状腺素指数观察甲功状态与乳腺癌的关系

我们测定了327例30岁以上健康妇女的FT_4I值,测定了124例(30岁以上女性)乳腺良性肿瘤患者和乳腺癌患者的FT_4I值。从我们测定的结果来看,FT_4I值的变化同年令有关,年令愈高,FT_4I愈低。将乳腺良性肿瘤患者的FT_4I值同乳腺癌患者的FT_4I值相比较,我们认为乳腺癌患者FT_4I值(40岁以上年令组)显示偏低倾向。     

单纯性肥胖儿童免疫功能的研究

使用流式细胞仪（ＦＣＭ）对１２名单纯性肥胖症儿童及２０名正常儿童进行了９项淋巴细胞亚群检测对比，结果发现肥胖症儿童ＣＤ３＋细胞、ＣＤ４＋细胞及ＣＤ４＋／ＣＤ８＋之比明显降低（Ｐ＜０．０１）；ＣＤ１９＋细胞、ＣＤ５６＋细胞、ＨＬＡ－ＤＲ＋细胞均出现有意义的升高；ＣＤ８＋细胞、ＣＤ２５＋细胞、ＣＤ５７＋细胞虽较正常儿童有所升高，但经统计学处理无明显差异。检测结果表明：单纯性肥胖儿童的免疫功能有较明显紊乱。提示肥胖症儿童的脂肪酸摄取过剩对免疫功能有一定损害。     

Elasticities for taxicab fares and service availability

This study utilizes a unique dataset from New York City to examine the effects of taxi fare increases on trip demand and the availability of taxi service. The elasticity of trip demand with respect to fares is estimated to be –0.22; the elasticity of service availability with respect to the taxi fare is 0.28; and the elasticity of service availability with respect to total supply of service is near 1.0. These results have important implications for taxi regulatory decisions. First, fare increases do substantially increase industry revenues but at a lesser rate than the percentage increase in the fare. The implication for policy-makers is that fare elasticities must be carefully considered to obtain desired improvements in drivers' earnings. Second, service availability -- an important aspect of service quality that is generally overlooked during fare policy debates -- should be a central consideration in fare setting, given the considerable impact of fares on availability. Finally, where the supply of cabs needs to be expanded, the number of cabs can be significantly increased without harming the revenue stream of existing operators. This finding alleviates a major industry objection to issuing additional taxicab licenses.     

Competition and public service obligations in European aviation markets

This paper analyzes the effect of universal service policies on the airline markets of five European Union countries (France, Germany, Italy, Spain and the United Kingdom) in the period 2002–2010. Results show that airfare discount schemes for island residents raise demand and positively affect competition and the number of flights at the route level. These effects are evident in France and Italy, but are particularly marked in Spain. By contrast, public service obligations (PSOs) reduce competition on the protected routes, while their effect on the number of flights differs depending on national regulations. In Spain, routes protected with PSOs have greater flight frequencies than those on unprotected routes of similar characteristics, but in France, Italy and the UK the opposite result is found. The empirical model also finds that on routes with low-cost airlines market concentration is smaller and there is a larger number of flights. This result is relevant for the design of universal service policy, since in recent years low-cost airlines have entered a number of thin routes and have increased access to air transportation.     

牵引定数不统一的港口后方腹地车流组织优化

线路区段牵引定数不统一是影响列车编组计划制定的重要因素,导致了列车在部分区段欠轴运行,在换重站或技术站进行补减轴作业.本文重点论述了减重方向列车编组方案的优化问题,提出了按充分条件将各种方案归类的方法,从而减少方案成本的对比次数,能快速获得最优的运送方案.在方案成本构成的分析过程中,充分考虑了各影响因素,将牵引机车费用看作与里程相关的可变成本,将欠轴列车浪费的机车和线路能力转化为惩罚费用,并考虑列车开行频率对方案费用的影响,最后从全网络的角度建立减重方向减轴列车编组优化模型.该模型既可获得合理的减重站,又能依据车流量关系选择优化的减轴编组方式,实例验证了模型的有效性.     

中心城区主干路改造的设计要点探讨

中心城区主干路一般建成时间较早,随着城市化进程的加快和社会经济的发展,现状市政交通、管线已不能满足沿线用户的需求;路面出现不同程度损坏,影响了行车的安全性和舒适性;沿线各类城市市政设施缺乏统一性和规范性,严重影响了道路交通和城市周边形象,制约了城市形象的提升和进一步发展.针对中心城区主干路改造的设计要点,从道路功能定位、纵断面控制、路面材料、轨道交通协调与管理、现有乔木的处理等方面进行阐述.     

Flexible long range planning using low cost information

Contemporary transport planning requires a flexible modelling approach which can be used to monitor the implementation of a long term plan checking regularly its short term performance with easily available data; the original model is periodically updated using low cost information and this allows the evaluation of the changes to the plan which may be required. Such an approach requires models suited to regular updating and to the use of data from different sources. Models to update trip matrices from traffic counts have been available for some time; however, the estimation and/or updating of other model stages with low cost data has escaped analytical treatment. The paper discusses this idea and formulates the updating problem for an example involving a joint destination/mode choice model under various assumptions about the nature of the available data. Analytical solutions are proposed as well as some general conclusions.requests for offprints