近年来,随着北京市机动车数量的快速增长,交通拥堵问题日益凸显.本文从私家车车主的角度分析使用机动车的成本与收益,利用外部性理论分析机动车使用数量过多的原因,并在借鉴国外经验的基础上,从成本内部化、环境保护、交通文化三个角度,提出建议与对策.

针对高铁票价与客运量,将中国与欧洲各国以及日本进行国际比较.相较于国外高铁票价,我国高铁每公里票价总体上低于国外,但是票价优惠措施不如法国、日本等国家灵活多样,过于固定.客运量方面的比较体现了我国高铁的快速发展,但是我国高铁旅客周转量在铁路客运中的比例较低,高铁在铁路客运市场的地位较低.通过国际比较,提出高铁票价优惠措施需多样化、灵活化,合理考虑民众支付能力,以提高高铁客运需求.

建立了低压真空环境单液滴闪蒸/冻结过程的热、质传递模型,探索液滴在真空闪蒸/冻结过程中的热动力学规律和机理.对液滴真空闪蒸/冻结过程中的温度、尺寸变化进行了计算,分析了环境压力、环境温度、液滴初始半径与初始温度等因素对液滴闪蒸预冷时间、快速凝固后继续冻结时间和升华再冷最低温度的影响.结果表明,模型能够很好地描述液滴真空闪蒸/冻结过程的基本特征;环境压力控制着闪蒸/冻结过程的主要特征及终态温度,是主要控制因素;液滴初始温度主要影响闪蒸速率,而初始尺寸则主要影响预冷时间;环境温度的影响可以忽略.

A typical binary aqueous solution with positive surface tension-temperature gradient was experimentally and numerically studied.In this present paper,the surface tension of a 1-pentanol aqueous solution was found to grow with the increase of the temperature under specific concentration and temperature range. To verify this special phenomenon,flow fields of the 1-pentanol aqueous solution under different horizontal temperature gradients were visualized and measured in a rectangular cavity by means of PIV method.And an inverse Marangoni convection different from that in pure liquid layer was investigated.For comparison,a numerical simulation was carried out to obtain the velocity distribution along the free surface of the 1-pentanol aqueous solution layer under same horizontal temperature gradients.Both results obtained by the experimental observation and numerical simulation were found to display similar tendency.

在工程热力学课程教学过程中,以强化研究型教学理念为目的,以突出专业特点为主线,从教学内容、教学方法、教学方式等多方面,进行了一些改革实践,有一些认识和体会与大家进行交流。

Experimental measurements of surface tensions have been carried out for 2-propanol,1-butanol and 1-pentanol aqueous solutions at different concentrations between 25 ℃ and 65 ℃ by Wilhelmy plate method.The results show a positive surface tension gradient with the temperature when the temperature exceeds a certain value at suitable concentrations,and it becomes more evident when the the number of Carbon atoms of the solute increases.

This paper introduces the basic principles of displacement ventilation ,then analyses the characters of displacement ventilation,and points out the advantages of displacement ventilation relative to mixing ventilation.

Basic principles are introduced about displacement ventilation,and successful simulation is done on the displacement ventilation of a meeting room.Result shows that CFD is a good way in the study of air distribution of displacement ventilation.

The efficiency is low and energy loss is great for linear motor, which is used as the propulsion part of a metro vehicle. In the view of economy, the research on energy loss and improving of running efficiency is of significance. This paper gives a brief introduction to the working principles of the linear motor on the metro vehicle, and analyzes energy loss in the working of linear motor.

The temperature and flow distribution in the compartment of Beijing DKZ1 underground airconditioning railcar is simulated by the software of FLUENT. Several typical sections are simulated and analyzed in the conditions of different inlets temperature and inlets velocity. The inlets temperature and inlets velocity satisfying human need for conformability are obtained. The results will provide reference for the design of airconditioning system of the urban railcar.

提出了一套新的城市餐饮业泔水处理方法,即将泔水中有营养价值的固态物质经过脱水、干燥、灭菌、粉碎等工序加工成可供牲畜直接食用的饲料.该方法应用了微波干燥杀菌和机械粉碎等技术来实现加工过程,具有设备简单、投资少、无二次污染等特点.

对设计的双燃料发动机电子控制系统硬件结构、软件模块、控制方式及用途进行了详细介绍,并预测了该技术的应用前景.

介绍了柴油机电控系统优化匹配的研究,分析了柴油机电控系统的优化任务,进行了电控系统优化方案的选择,并建立了电控系统优化的数学模型,提出了切实可行的最优化方法,给出了柴油机电控系统优化的过程与步骤.