驱动桥集成建模系统概要设计

利用面向对象的特征建模方法，从分析系统功能需求出发，构建驱动桥集成建模过程的对象－关系模型；通过提取驱动桥的共同特征，建立驱动桥总体及组件的特征几何及其语义；采用C语言中的“类”对系统功能模块和控制模块元素及成员函数进行封装；拟利用有限元方法，对几何模型中的受力件进行强度校核；通过有限回溯，以期值得优化的驱动桥产品数据模型。     

有关汽车内部声场模态分析的几点讨论

在新车身的概念设计阶段，由于汽车内部诸多因素的不确定以及开发时间的限制，在应用有限元法进行车内声学特性预评估时须对车内声腔模型做简化处理。其中，以二维模型代替三维模型、忽略座椅所占空间、不计结构与声场之间的耦合作用以及不计内饰和座椅表面的吸声效果等是四种常见的车内声场建模的简化方法。文中讨论了这些简化方法对车内声学模态分析结果的影响程度，对正确处理车内声场建模精度与计算效率之间的关系、建立满足工程要求的经济型有限元声场模型有一定指导意义。     

铁路车站取送车作业问题的一般模型

在各种装卸地点布置形式、各种到发车流、各种取送车作业组织方式条件下,将合理取送顺序、合理取送批次数和合理取送时机作为一个整体,研究铁路车站取送车作业问题.以取送车作业顺序偏序关系、装卸区容车能力、相异放射枝不能同批、调机牵引能力、交货时间窗为约束条件,以站内货车处于取送车作业状态的时间最少为优化目标,建立取送车作业问题的一般模型.模型的每个解都对应1个完整的取送车作业方案,设计了解的编码型式.利用排列组合理论和方法分析取送车作业问题解的结构关系,证明取送车作业问题是具有取送车作业批次和顺序2个优化维度的调度问题.     

城轨辅助变流器热设计方法研究

针对辅助变流器热设计的需求,建立有限体积法的迭代方程,并结合城轨辅助变流器的热设计,提出热仿真的设计步骤与方法。依照此方法建立北京城轨13号线辅助变流器箱体与内部主要电气部件的数学模型,采用仿真与公式计算结合的IGBT热损耗计算方法,使用六面体网格离散时间与空间域的模型,借助流体力学软件迭代有限体积法方程进行热仿真的计算,计算结果满足温升要求。依据此热设计结果试制成样机,完成稳态温升试验,并将主要电气部件试验结果与仿真结果进行对比。结果满足设计初衷,验证了有限体积法的热仿真分析方法的可行性。     

Modeling wrong-way crashes and fatalities on arterials and freeways

Wrong way driving (WWD) research and mitigation measures have primarily focused on limited access facilities. This is most likely due to the higher incidence of fatal WWD crashes with dramatic consequences on freeways, media attention, and a call for innovative solutions to address the problem. While public agencies and published literature address WWD incidence on freeway systems, the crash analyses on non-limited access facilities, i.e., arterial corridors, remains untouched. This research extends previous works and attempts to provide many new perspectives on arterial WWD incidence. In particular, one work showed that while WWD fatalities are more likely to occur on freeways, the likelihood of these crashes is higher on arterials. Hence this work with univariate and multivariate analyses of WWD and non-WWD crashes, and fatal and non-fatal WWD incidents. Results show the impressive negative impacts of alcohol use, driver defect, nighttime and weekend incidence, poor street lighting, low traffic volumes, rural geography, and median and shoulder widths. The objective here is to highlight the need for paying greater attention to WWD crashes on arterial corridors as is done with fatal WWD incidents on freeway systems. It suffices to say that while engineering countermeasures should evolve from the traditional signing and pavement markings to connected vehicle technology applications, there is a clear and compelling need to focus on educational campaigns specifically targeting drunken driving, and enforcement initiatives with an objective to mitigate WWD in the most efficient manner possible.     

摩托车车架振动性能优化的设计研究与应用

针对某款250型新开发摩托车车架,利用有限元理论建立整车参数化动力学模型,运用模态分析技术、谐响应分析技术、全局灵敏度分析技术及优化设计技术,分析车架动态特性及发动机激励下车架的振动响应,并改进了车架结构以降低振动,总结出一套摩托车车架振动性能优化设计流程,为类似产品的设计提供了参考。     

基于CAXA的曲面型腔模具加工方法研究

文章以曲面型腔模具为载体,应用CAXA制造工程师软件完成对产品进行三维建模,对零件加工工艺进行分析,并比较几种加工方案,生成刀具加工轨迹进行数控仿真加工。在加以验证后,提出了较为合适的加工方案,生成G代码,最后利用数控机床对产品进行加工,提高了加工精度与生产效率,节约了成本。     

热工流体网络建模在船舶蒸汽动力系统仿真中的应用

本文以船舶蒸汽动力系统仿真建模过程为例,介绍了热工流体网络手工建模的基本方法和特点。配合自动化建模工具JTOPment在两相流建模的优势,结合汽轮机组、凝汽系统、供水系统、供油系统和送风的教学模型,最终确定了该工况下的整体系统模型,从而为下一步系统仿真提供参考。     

An eddy-permitting, coupled ecosystem-circulation model of the Arabian Sea: comparison with observations

A nitrogen-based, pelagic ecosystem model has been coupled with an eddy-permitting ocean general circulation model of the Arabian Sea, and the results are compared with observations. The seasonal variability simulated by the model is in good agreement with observations: during the southwest monsoon season, phytoplankton increases in the western Arabian Sea due to upwelling along the coast; during the northeast monsoon season, phytoplankton abundance is large in the northern Arabian Sea because of the enhanced nitrate entrained by relatively deep vertical mixing. Two major differences are, however, found in the basin-wide comparison between model results and observations: an unrealistic nitrate maximum in the subsurface layer of the northern Arabian Sea and too low primary production in oligotrophic regimes. The former may be attributed to the lack of denitrification in the model. Possible causes for the latter include the present model's underestimation of fast nutrient recycling, the neglect of carbon fixation decoupled from nitrogen uptake and of nitrogen fixation, and inadequate nitrate entrainment by mixed layer deepening. The rate at which simulated nitrate increases in the northern Arabian Sea is 11–24 TgN/year, and should correspond to the denitrification rate integrated over the northern Arabian Sea assuming that the loss of nitrogen through denitrification is balanced by advective input. The model does not reproduce the observed phytoplankton bloom in the late southwest monsoon season. Possible causes are that the mixed layer may be too shallow in summer and that the horizontal transport of nitrate from the coast of Oman may be too weak. Sensitivity experiments demonstrate a strong dependence of the simulated primary productivity on the vertical mixing scheme and on the inclusion of a fast recycling loop in the ecosystem model.     

困境区域引起的无意闯红灯违规分析

本文分析了车辆在交叉口由于车辆的行驶速度较高或野蛮驾驶造成的闯红灯行为,其中除了应当给予惩处的驾驶员的故意行为以外,也包括无意闯红灯行为。无意闯红灯的原因和特点同城市交叉口的宽度、理想速度、车辆动力学特点、交通信号灯的黄灯间隔时间以及困境区域有关。本文给出了由困境区域引起的无意闯红灯违规的数学描述, 建立了用于城市道路交叉口闯红灯违规的模型,利用该模型对西安部分地区的数据进行仿真和评价。