电喷汽油机可变进气系统的优化设计

利用发动机一维气体流动模拟程序，对某电喷汽油机进气系统的流动过程进行了模拟计算。对该汽油机采用的可变进气系统的歧管直径和长度、控制阀开关的切换转速等结构参数进行了优化设计。计算结果表明，与原机相比，经优化设计后系统的充气效率最大增加幅值大于11％，且改变了充气效率随转速的变化趋势。分析了配气正时对可变进气系统充气效率的影响。     

PDM在客车制造企业的应用规划

PDM（产品数据管理）技术在制造业中的应用正在迅速普及。本文结合为武汉客车厂开发PDM的实际经验。阐述客车制造企业开发PDM的规划。     

二级踏步LPG单燃料城市客车底盘的开发

论述骏威公司二级踏步LPG城市客车底盘的开发、产品结构特点及主要技术性能参数.     

谈工程量清单计价方法在造价控制中的应用

为了在建设项目设计阶段、招投标阶段及项目实施阶段逐渐推行工程量清单计价管理方法,来取代传统计划经济体制下的工程定额计价管理办法,笔者结合近两年从事国内公路工程造价管理工作中对工程量清单计价方法在工程造价控制方面应用的情况以及问题的处理,对清单的编制和审查、不平衡报价的合理使用以及工程变更和结算等方面的问题提出一些思考和看法,使清单计价方法进一步完善。     

高填路堤沉降变形规律研究及压实技术课题成果简介

西部课题“高填方路堤沉降变形规律研究及压实技术”针对高填方路堤典型病害、高路堤沉降计算方法、高路堤工后沉降预估方法、以及典型填料压实技术等方面进行了较为系统深入研究,取得了较丰富的成果.本文对该课题主要研究工作和研究成果进行了介绍,供同行参考.     

城市高架桥之高独柱墩横向位移探讨

结合城市高架高独柱墩顶部发生横向位移这一现象,对高独柱墩顶部横向荷载产生的原因进行初步分析,并应用三维非线性屈曲分析,阐述组合荷载所引起的大变形及混凝土徐变效应与墩顶横向位移之间的关系,提出了设计、施工类似结构时应注意的事项。     

Shockwave-based queue estimation approach for undersaturated and oversaturated signalized intersections using multi-source detection data

With the progress of information and sensing technologies, estimating vehicular queue length at signalized intersections becomes feasible and has attracted considerable attention. The existing studies provided a solid theoretical foundation for the estimation; however, the studies have some restrictions or limitations more or less. This paper presents a new methodology for estimating vehicular queue length at signalized intersections using multi-source detection data under both undersaturated and oversaturated conditions. The methodology applies the shockwave theory to model queue dynamics. Using data from probe vehicles and point detectors, analytical formulations for calculating the maximum and minimum (residual) queue lengths of each cycle are developed. Ground truth data were collected from numerical experiments conducted at two intersections in Shanghai, China, to verify the proposed methodology. It is found that the methodology has mean absolute percentage errors of 17.09% and 12.28%, respectively, for maximum queue length estimation in two tests, which are reasonably effective. However, the methodology is unsatisfactory in estimating the residual queue length. Other limitations of the proposed models and algorithms are also discussed in the paper.     

Simulation of mixed gas formation for a spray-wall complex guided LPG direct injection engine

To obtain an ultralean air-fuel ratio and to reduce engine-out NOX and HC emissions induced by the richer mixture near the spark plug, a spray and wall complex guided combustion system has been developed by utilizing the fuel characteristics of LPG. The new combustion system configuration is optimized by using a commercial CFD code, FIRE V2013, and the reliability of the system has been experimentally demonstrated by Plane Laser-Induced Fluorescence (PLIF). The mixture formation in the new combustion system under part load (2,000 rpm) is numerically simulated. With an injection timing of 40°CA BTDC, the LPG spray which is injected from two upper holes, reaches the ignition point, and the other part of the LPG spray which is injected from the bottom hole, is directed to the ignition point through the vertical vortices at the same time. At the ignition timing of about 20°CA BTDC, the two-part mixtures have been shown to form a stable and richer stratified mixture around the ignition point, and the maximum global air-fuel ratio reaches to 60: 1.     

Wave propagation in head on bonnet impact: Material and design issues

Head on bonnet impact is becoming more and more important in automotive design as regulations on pedestrian safety become more demanding. Despite the relatively low amount of energy involved, these impacts are truly dynamic phenomena as the event duration is comparable with the traveling time of the different wavefronts generated by the impact. In this paper, we show that we can build up a simplified model for the impact based on wave propagation analysis. Using this model, we can analyze head acceleration on existing bonnets or predict it on new ones. Head acceleration in a bonnet impact can thus be estimated over the whole area of the bonnet with a few minutes of CPU.     

Comparison of fuel efficiency and exhaust emissions between the aged and new DPF systems of Euro 5 diesel passenger car

This study was conducted to examine the impact of aged and new DPF systems of the Euro 5 diesel passenger car on fuel efficiency and exhaust emissions. Test diesel vehicle used in this study was equipped with diesel oxidation catalyst (DOC) and diesel particulate filter (DPF) as aftertreatment systems, and satisfied the Euro-5 emissions standard. The displacement volume of engine was 1.6 L and the cumulative mileage was 167,068 km before the test. The FTP-75 test procedure was used, and the time resolved and weight based exhaust emissions of total hydrocarbon (THC), carbon monoxide (CO) and nitrogen oxides (NOx) were measured. The results show that the vehicle with the new DPF system has lower emissions of THC, CO and NOx than the aged one, and fuel efficiency also increased about 5 percent. The aged DPF system had higher backpressure due to the particulate matter (mostly in the form of ash) accumulated in the DPF. As was shown in the analysis using X-CT (X-ray computer tomography), the aged DPF system had particulate matter (PM) accumulated to a length of 46.6 mm. In addition, a component analysis of PM through XRF (X-ray fluorescence) analysis found that 50 % or more of the components consisted of the P, S, Ca, and Zn.