Effects of Residual Ash on Dpf Capture and Regeneration

To study the effects of residual ash on the capture and regeneration of a diesel particulate filter (DPF), repeated capture and complete regeneration experiments were conducted. An engine exhaust particulate sizer was used to measure the particle size distribution of diesel in the front and back of DPF. Discrepancies in the size distribution of the particulate matter in repeated trapping tests were analyzed. To achieve complete DPF regeneration, a DPF regeneration system using nonthermal plasma technology was established. The regeneration carbon removal mass and peak temperatures of DPF internal measuring points were monitored to evaluate the effect of regeneration. The mechanism explaining the influence of residual ash on DPF capture and regeneration was thoroughly investigated. Results indicate that the DPF trapping efficiencies of the nuclear-mode particles and ultrafine particles have significant improvements with the increase quantity of residual ash, from 90 % and 96.01 % to 94.17 % and 97.27 %, respectively. The exhaust backpressure of the DPF rises from 9.41 kPa to 11.24 kPa. Heat transfer in the DPF is improved with ash, and the peak temperatures of the measuring points accordingly increase. By comparing the regeneration trials, the elapsed time for complete regeneration and time difference for reaching the peak temperature between adjacent reaction interfaces are extended with increased quantity of ash. The carbon removal mass rises by 34.00 %.     

某商用车散热器面罩开裂分析与改进

为解决散热器面罩开裂问题,提出了焊点优化方案和散热器面罩加强板外置/加强板内置方案,并进行了模块化设计,制定了2组改进措施。有限元分析结果表明:2种改进措施与原状态相比,均有良好应力改善效果,满足应力要求。     

连续长大下坡路段交通事故特征分析

在对连续长大下坡路段交通事故数据和道路设计参数调查的基础上, 分析了连续长大下坡路段的交通安全状况, 讨论了急弯陡坡、连续陡坡和连续缓坡3种线形组合形式路段的交通事故特征和事故原因。结合典型长大下坡路段的交通事故数据, 运用数理统计与回归分析方法, 研究了交通事故与道路纵断面参数之间的关系。分析结果表明: 在连续长大下坡路段地点坡度为3%~4%时, 事故率最高; 事故率与事故发生地点前2 km以上路段平均坡度呈显著的指数关系, 所建立回归模型的判定系数高于0.84。     

武器系统使用可用性评估模型及应用

  目的  针对现有的舰船战备完好性评估方法已无法满足海军任务保障需求这一问题,提出基于云模型的新型评估方法。  方法  首先,在指标确定过程中,基于合作博弈权重方法,将层次分析法、熵权法和灰色关联度法所计算的权重进行合作博弈,从而拟合得到组合定权重,并引入变权重理论对定权重进行修正优化;然后,引入云模型理论,利用云相似度替代隶属度,设计基于云模型的模糊综合评估模型;最后,以舰船对空防御任务为例,评估舰船战备完好性。  结果  仿真结果表明：变权重模式下,基于云模型的模糊综合评估结果可以更准确地反映实船战备状态。  结论  研究成果可为舰船战备完好性评估提供参考。     

多项式基函数神经网络的结构可靠性分析

  目的  随着液化天然气（LNG）船舶结构研究和设计深度的提高,需要有能够快速和准确地评估不确定性因素的可靠性分析方法。为此,提出基于改进随机森林−蒙特卡罗（RF-MC）法来解决A型独立液舱支座结构失效概率的计算问题。  方法  首先,根据不确定性因素的概率分布,使用MC法生成样本集;然后,以局部离群因子为准则,筛选出失效面附近的样本点,再对筛选出的样本点进行有限元计算后添加至训练集,通过重复训练随机森林近似模型,直至满足精度要求;最后,使用近似模型判别样本点是否失效,结合MC法计算结构的失效概率。  结果  综合考虑算法的准确率、复杂度和效率并结合算例1和2,可以发现在分析可靠性问题时改进RF-MC法比MC和BP-MC等方法具有更大优势。算例3的应用结果表明了改进RF-MC法在A型独立液舱支座结构可靠性分析中的适用性。  结论  研究结果可为LNG船舶的优化设计提供可行的技术方案。     

Characteristics analysis for travel behavior of transportation hub passengers using mobile phone data

The travel behavior of passengers from the transportation hub within the city area is critical for travel demand analysis, security monitoring, and supporting traffic facilities designing. However, the traditional methods used to study the travel behavior of the passengers inside the city are time and labor consuming. The records of the cellular communication provide a potential huge data source for this study to follow the movement of passengers. This study focuses on the passengers’ travel behavior of the Hongqiao transportation hub in Shanghai, China, utilizing the mobile phone data. First, a systematic and novel method is presented to extract the trip information from the mobile phone data. Several key travel characteristics of passengers, including passengers traveling inside the city and between cities, are analyzed and compared. The results show that the proposed method is effective to obtain the travel trajectories of mobile phone users. Besides, the travel behavior of incity passengers and external passengers are quite different. Then, the correlation analysis of the passengers’ travel trajectories is provided to research the availability of the comprehensive area. Moreover, the results of the correlation analysis further indicate that the comprehensive area of the Hongqiao hub plays a relatively important role in passengers’ daily travel.

     

广西交通科技资源共享平台建设探讨

文章针对广西交通科技项目管理系统现状,分析了建设交通科技资源共享平台的必要性,阐述了交通科技资源共享平台建设的关键技术、创新点及主要内容,指出该共享平台的建设可改善和提高交通运输科技项目质量及监管水平。     

模拟计算法在重型车辆燃油经济性标准中的应用研究

随着节能减排压力的日益严重,世界各国均开始制定重型车辆的燃油经济性标准。在对重型车燃油经济性的测量方面,模拟计算法由于操作简单、可重复性好、成本低的优点越来越受到行业的重视,在日本、中国和美国的标准中都得到了应用。本文在分析模拟计算法测量车辆燃油经济性的原理基础上,对比研究了日本、中国和美国标准中模拟计算法的应用情况,分析了各国在模拟计算法关键环节上策略的异同。     

低浓度表面活性剂减阻流体的性能

  目的  为了短时提高水炮的射程与流量,提出在水炮系统中采用添加剂湍流减阻技术。  方法  首先,通过圆管海水湍流减阻实验验证典型减阻添加剂对于海水系统同样有效;其次,建立水炮系统水力学模型;最后,提出一种两级减阻剂夹缝筛孔自动注入系统,在水炮系统运行过程中,减阻剂搅拌/注入交替进行,利用柱塞泵伴随添加相应流量的减阻剂。  结果  模拟研究表明,系统能够在15 min效用强化期内使水炮射程增加约20%,流量增加约8%。  结论  基于添加剂湍流减阻技术可实现水炮系统“兴奋剂”强化,具有良好的应用潜力。     

基于Plant Simulation的后桥线仿真优化

以F公司后桥装配线为例,针对装配线存在的生产效率低、等待时间长、忙闲不均等问题,在精益思想的指导下根据ECRS原则对装配线的瓶颈工序进行改善,取消不必要的工艺流程,对工人行走路线进行重新规划。另外,对装配线的任务进行重新分配。用Plant Simulation仿真软件对装配线改善前后进行对比分析,结果表明,优化后的装配线节拍降低,日最大产能提高,平衡率增加。