Key factors controlling the real exhaust emissions from earthwork machines

This study focuses on the actual exhaust emissions of regulated and unregulated pollutants from earthwork machines (EM). In addition to providing a realistic assessment of gaseous and particulate emissions from key EM and filling critical data gaps in emission inventories, it emphasizes the importance of breaking down the average operating emission factors into task-related emission factors (TEF). The latter serve many goals, namely by: categorizing EM in relation to their emission dynamics, finding emission determinants and proposing on-site emission mitigation strategies. These have also led to a more refined analysis of both the effectiveness of EU and US emissions standards and the accuracy of NONROAD2008 model. Ultimately, by using task-related emission factors in conjunction with data available from the literature and with the methodology developed by US-EPA, a lower bound was estimated for gaseous exhaust emissions from the major construction vehicles operable at earthwork sites.     

船用柴油机排气温度监测系统设计

本文设计了一个柴油机排气温度的实时监测系统。测量元件采用带电桥补偿的热电偶,信号处理电路采用了基于LM324的仪用放大电路,选择ATmega8作为系统的数字处理芯片。     

摩托车发动机气门阀座的加工与刀具介绍

单刃可调硬质合金铰刀类刀具,结构比普通铰刀刀具复杂,由于有导向条的导向、支撑等作用,加工精度比普通铰刀类刀具要高,但这种刀具使用不当很容易折断;普通铰刀类刀具, 结构相对简单,调刀、换刀容易,调刀简单,完全能满足加工精度要求。     

一次制动模式参数选择

通过研究减速度法，考虑实际应用情况，根据在额定减速度和变减速度2种制动模式下的不同初速度，计算对应的制动总距离；通过Matlab编程仿真关于速度一距离的模式曲线；最后，验证了在几种车型上的实际应用情况。     

悬架偏频对制动性能影响分析

制动性能是衡量车辆好坏的一个重要指标,世界上任何一个国家对此都有严格要求。本文着重介绍一款轻型载货车辆在设计验证过程中,车辆空载行驶速度超过40km／h时,在紧急制动情况下后桥出现抖动现象。通过对车辆制动系统、悬架系统全面分析,找到问题所在,最后在不影响车辆性能的前提下,通过适当调整后悬架板簧的刚度达到解决车辆制动抖动。     

动力转向器复合棱边坡口转阀静特性的计算分析

分析了动力转向器阀芯棱边与静特性的几何关系,提出采用直线与圆弧组合成阀芯复合棱边取代传统的单段圆弧结构,以改善传统产品高速行驶不灵敏区过大、常用工作区手感差的问题.理论计算和试验结果表明,复合棱边阀口静特性比传统结构更符合理想曲线,多项性能指标均明显提高.     

排气管内二维非定常流动的计算研究

为了优化设计排气管形状，本文研究了柴油机排气管内二维非定常湍流流动的计算，排气管与气缸交接处的边界条件由实验结出，湍流模型采用k－ε模型。计算了一根3缸模型排气管内排气流动变化，计算结果与实验结果吻合良好。该研究对排气管的形状设计有一定的应用价值。     

制动鼓传热分析

对某重型卡车后轮制动鼓进行传热分析,模拟制动鼓的温升过程,并与三种不同改进结构的制动鼓进行对比分析,提出最优改进设计方案。     

Effect of wheel-slip prevention based on sliding mode control theory for railway vehicles

It is important to consider the robustness when designing brake control systems, because of the model's uncertainties that result from the nonlinear characteristics of wheel-to-rail adhesion forces and brake material friction coefficients. This paper presents the experimental results from the new wheel-slip prevention control using nonlinear robust control theory. The authors performed experiments for the proposed wheel-slip prevention control to compare it with the conventional control laws. The experimental results proved the comparative effectiveness of the proposed control and showed high brake performance under nonlinear characteristics of brake dynamics.