基于某车型的减振器调试与速度测试方法探讨

在汽车底盘的研发过程中,减振器的性能对整车舒适性和平顺性等有着非常重要的影响。为了解如何通过路试数据的采集来获取减振器振动速度,使减振器的调试得到一个有效的指导方向,从而更好地掌握减振器的调试方法,文章特以国内某款车型的减振器调试为例进行研究,并基于MATLAB/GUI,为减振器节流阀片的选取开发了一项图形用户界面工具,使用户能够更快速、高效的选取节流阀片,提高工作效率,也为减振器的调试提供了新的参考方法。     

基于VISA技术的高速USB数据采集系统

高速USB数据采集系统的设计严格遵循USB2.0协议,实现了主机和测试设备之间简单、快速、可靠的连接和通信.该文介绍了这种数据采集系统的硬件组成、驱动程序和固件程序的设计以及采用虚拟仪器软件LabWindows/CVI在VISA技术上开发应用程序的设计方法.     

The Effect of Circulation Fan on Energy Consumption in Nature Convective Refrigerator-Freezer

The effect of the circulation fan installed in fresh food compartment on energy consumption of natural convective refrigerator/freezers (RFs) was experimentally studied. Five different RF models with different cycles were tested. The experimental results showed that the energy consumption of the single-loop cycle RF increased by 2.4%~3.8%, that of the bypass two-circuit cycle RF decreased by 1.0%, and that of the two-circuit cycle RF with its evaporators in parallel when the geometry parameters of refrigeration system and the refrigerant charge were not changed after the circulation fan was installed decreased by 3.3%. When the optimization on the refrigerant charge and the evaporator was carried out, the energy consumption of the single-loop cycle RF , the bypass two-circuit cycle RF and the two-circuit cycle RF with its evaporators in parallel, decreased by 1.0%~6.4%, 3.25% and 3.26% respectively. The present conclusions will provide a guideline to the optimum design for the RF with the circulation fan.     

Environmental impacts of transformative land use and transport developments in the Greater Beijing Region: Insights from a new dynamic spatial equilibrium model

This paper reports the insights into environmental impacts of the ongoing transformative land use and transport developments in Greater Beijing, from a new suite of dynamic land use, spatial equilibrium and strategic transport models that is calibrated for medium to long term land use and transport predictions. The model tests are focused on urban passenger travel demand and associated emissions within the municipality of Beijing, accounting for Beijing’s land use and transport interactions with Tianjin, Hebei and beyond. The findings suggests that background trends of urbanization, economic growth and income rises will continue to be very powerful drivers for urban passenger travel demand across all main modes of transport beyond 2030. In order to achieve the dual policy aims for a moderately affluent and equitable nation and reducing the absolute levels of urban transport emissions by 2030, road charging and careful micro-level coordination between land use, built form and public transport provision may need to be considered together for policy implementation in the near future.     

The endogeneity of OECD gasoline taxes: Evidence from pair-wise,heterogeneous panel long-run causality tests

Despite the current interest in using fuel taxes as an instrument for climate policy, there has been little study of current automotive fuel tax regimes. We expand on two earlier cross-sectional studies on why fuel taxes differ across countries by using OECD panel data and employing heterogeneous panel cointegration and long-run panel Granger-causality techniques. We confirm some of those earlier studies’ conclusions. Further, we find that governments that rely on consumption-based taxes for revenues will have higher gasoline tax rates (than governments that rely on income and wealth/property-based taxes). But more significantly, we determine that higher gasoline demand among consumers “causes” democratic governments to set lower gasoline taxes—a finding with important implications for today’s climate/energy policy debate.     

The effect of railway local irregularities on ground vibration

The environmental effects of ground-borne vibrations generated due to localised railway defects is a growing concern in urban areas. Frequency domain modelling approaches are well suited for predicting vibration levels on standard railway lines due to track periodicity. However, when considering individual, non-periodic, localised defects (e.g. a rail joint), frequency domain modelling becomes challenging. Therefore in this study, a previously validated, time domain, three-dimensional ground vibration prediction model is modified to analyse such defects. A range of different local (discontinuous) rail and wheel irregularity are mathematically modelled, including: rail joints, switches, crossings and wheel flats. Each is investigated using a sensitivity analysis, where defect size and vehicle speed is varied. To quantify the effect on railroad ground-borne vibration levels, a variety of exposure–response relationships are analysed, including: peak particle velocity, maximum weighted time-averaged velocity and weighted decibel velocity. It is shown that local irregularities cause a significant increase in vibration in comparison to a smooth track, and that the vibrations can propagate to greater distances from the line. Furthermore, the results show that step-down joints generate the highest levels of vibration, whereas wheel flats generate much lower levels. It is also found that defect size influences vibration levels, and larger defects cause greater vibration. Lastly, it is shown that for different defect types, train speed effects are complex, and may cause either an increase or decrease in vibration levels.     

Prohibited–permitted right-turn phasing strategy based on capacity analysis of right-turn movements

In traffic-crowded metropolitan areas, such as Shanghai and Beijing in China, right-turn vehicles that operate with a permitted phase at signalized intersections are normally permitted to filter through large numbers of pedestrians and bicycles. To alleviate such conflicts and improve safety, traffic engineers in Shanghai introduced a prohibited–permitted right-turn operation, adding a subphase to the permitted phase in which right-turns are prohibited. Unfortunately, the prohibited subphase would reduce the capacity of right-turn movements when it prohibits right turns even if there are few pedestrians and bicycles crossing the street. This paper aims at quantifying the impact of both non-vehicular flows and the prohibited subphase on the right-turn capacity, and then proposes a strategy to determine appropriate prohibited–permitted right-turn operation that minimizes the capacity reduction caused by the prohibited subphase. To achieve this goal, we improved the pedestrian and bicycle adjustment factor described in the Highway Capacity Manual by taking into account: (1) the variety in space competition between pedestrians and bicycles, and (2) the effect of two conflict zones in each phase on right-turn operation. In addition, we revised the capacity estimation model in the Highway Capacity Manual, and developed a model based on bicycle/pedestrian volume fluctuation to describe the capacity reduction due to both non-vehicular flows and the prohibited subphase. Furthermore, we proposed a timing strategy for the onset and duration of appropriate prohibited subphase. When bicycle and pedestrian volumes are low, the actuated strategy turns to the permitted phase. When these volumes are moderate, the strategy turns to the prohibited–permitted operation. With the volumes increasing, the prohibited subphase onset advances and duration increases. In these two scenarios, the new strategy has higher right-turn capacity than the current pretimed prohibited–permitted operation. Unfortunately, when bicycle and pedestrian volumes are high, the strategy yields similar right-turn capacity. However, the new prohibited subphase has less potential vehicle–bicycle and vehicle–pedestrian conflicts.     

舰艇抗爆抗冲击技术现状和发展途径

  目的  为了分析玻璃纤维-芳纶（FRC）底材涂覆硬质聚脲的复合结构的抗冲击性能,  方法  采用口径12.7 mm的弹道枪进行破片冲击加载,得到破片的弹道极限速度,分析获得不同工况下复合结构靶板的极限比吸收能。在此基础上,结合靶板的宏观破坏形貌,讨论2种不同聚脲涂覆复合结构的抗冲击性能的优劣性,并与软质聚脲涂覆复合结构进行对比,以验证涂覆硬质聚脲复合结构的最佳抗冲击性能。  结果  研究表明,作为背弹面涂层时,软质聚脲涂覆复合结构的抗冲击性能较好;作为迎弹面涂层时,硬质聚脲涂覆复合结构的抗冲击性能较好;两种聚脲涂层作为迎弹面的复合结构抗冲击性均优于背弹面和双面复合结构。  结论  在一般工程应用防护中,选用高硬度聚脲材料作为迎弹面涂层的防护效果更好。     

3×340m公铁合建多塔斜拉桥结构体系研究

珠机城际金海特大桥主桥采用(58.5+116+3×340+116+58.5) m四塔三主跨斜拉桥,为国内首座公铁平层合建的多塔斜拉桥。金海桥塔多联长,采用何种结构体系提高结构刚度、减小温度效应及改善结构受力是结构设计的关键。为此,在总结既有多塔斜拉桥经验的基础上,比选了半漂浮体系、刚构-半漂浮体系、梁式支承体系以及首次在多塔斜拉桥应用的刚构-连续体系。通过对4种结构体系的刚度,结构受力等分析,并考虑构造要求和经济性,推荐采用刚构-连续体系,即两中间塔墩梁固结,两边塔梁固结、塔墩分离。该体系有效提高了结构整体刚度,主梁、桥塔及斜拉索受力较优,同时降低了温度效应的不利影响,车桥动力仿真分析结果表明,桥梁的振动性能良好,行车舒适性优。     

舰船消磁系统综述

为使消磁时消磁线圈上的能量能够回馈到消磁电源、提高能源利用率,提出基于超级电容和锂电池混合供电的消磁电源控制策略。

通过研究消磁线圈强耦合工况下的电气特性,引入超级电容和锂电池混合供电的消磁电源系统。将消磁线圈电流的变化分为上升、保持、下降（能量回馈）3个阶段,在消磁线圈电流变化的不同阶段,控制相应功率器件的开通和关断。借助Matlab/Simulink进行仿真,分析仿真结果,以验证基于超级电容和锂电池混合供电系统的能量回馈控制策略的可行性。

仿真结果表明,流经各消磁线圈的总电流值可以快速上升至消磁额定电流值,并稳定在额定值附近,且超调量较小。

超级电容和锂电池混合供电的消磁电源系统能够将消磁线圈上的能量回馈至超级电容中,减少整套消磁系统的能源损耗。