铁路危险货物办理站布局优化双层规划模型与算法

根据国家标准中规定的常见危险化学品在存储区的临界量,提出布局优化阶段的铁路危险货物办理站环境风险评估模型.在此基础上,根据铁路决策部门与危险货物运输客户之间的主从递阶决策关系,建立铁路危险货物办理站布局优化问题的双层规划模型.上层规划模型以一定区域内危险货物办理站环境风险最小化而运量最大化为目标,下层规划模型以客户运输费用最小化为目标.采用该模型可以合理确定危险货物办理站的地理位置及承办危险货物的类别.通过构造上、下层决策变量间的反应函数,设计模型的启发式求解算法.算例验证了模型及其算法的可行性和有效性.     

大跨度中承式钢箱桁架拱桥空间稳定性分析

随着钢箱桁架拱桥跨径的增大,其空间稳定性问题更为突出,对大跨径钢箱桁架拱桥稳定性及影响因素进行分析,具有重要的实际工程意义。某桥为主跨519 m的中承式钢箱桁架拱桥,通过对其建立空间有限元模型进行线弹性稳定分析,结果表明:大跨径中承式钢箱桁架拱桥活载对稳定性影响较小,结构失稳一般表现为面外失稳,且最容易发生在拱圈无平联区域。对稳定性的影响因素进行分析表明:菱形和"K"字形对提高稳定性效果最佳;斜吊杆较竖吊杆能提高面内稳定性,但降低了面外稳定性;初始几何缺陷不会显著降低大桥的线弹性失稳荷载。     

我国电动汽车充换电基础设施标准的现状和发展建议

为了能够更加合理地制修订我国电动汽车充换电基础设施的相关标准,进一步促进电动汽 车推广应用目标的顺利实现,对我国现有的充换电基础设施相关标准开展了研究。首先,对国外 充换电基础设施标准概况和我国相关的主要国家标准、行业标准、地方标准和企业标准进行了介 绍;接着,对我国现有标准中关于充换电设备、充电接口及通信协议、充换电计量装置、充换电 站的相关规定进行了分类介绍,明确了现有标准对于确保电动汽车用户充换电体验质量的重要意 义;然后,针对电动汽车用户完整的充换电流程,对实际中用户存在的充换电服务需求进行了分 析;最后,根据用户的实际服务需求,提出了我国未来充换电基础设施标准的制修订建议。研究 结果表明,我国现有的充换电基础设施标准基本确保了充换电设备的可用性和易操作性、充电接 口的通用性、充电计量装置的准确度以及充换电站的运营安全等,未来应针对充换电设备状态查 询、直流充电桩的兼容性、统一支付、充换电站规模和布局等方面制定相关标准,以提高电动汽 车用户体验质量和促进电动汽车的进一步推广应用。     

Investigation of Occupant Lower Extremity Injures under Various Overlap Frontal Crashes

Objective

With widely usage of restraint system, fatal injuries to occupants have been largely limited while non-fatal lower extremity injuries have not been effectively improved. The present study aims to investigate occupant lower extremity injuries under realistic impact environments.

Methods

A biofidelic lower extremity model, a dummy model and a car cab model were combined to set up a realistic impact environment. Three typical frontal impact groups were simulated. Occupant global lower kinematics, long bone axial force and bending moment were presented to in-depth investigate lower extremity injury mechanism and tolerance.

Results

Various overlap frontal impacts cause totally different lower extremity kinematics in the combination of structural invasion and restraint system effects. The femur fracture occurred at a small axial force of 7.57 kN combing a substantial bending moment peak of 172 Nm. Ankle joint injuries were found in 100 % and 25 % overlap impacts that present large tibial axial force and joint rotation angle.

Conclusions

Overall results indicate that a coupling threshold of femur axial force and bending moment is of rationality to predict global femur fracture. The ankle joint injury occurrence is significantly related to the coupling effects of tibia axial force and excessive self-kinematics.

     

Technology application and development trend of intelligent unmanned system北大核心CSCD

Intelligent unmanned system combat is moving from concepts to actual combat applications. The military applications of intelligent unmanned systems are emphasized by focusing on the needs of the combat missions that they will undertake on future battlefields and summarizing the development statuses of land, air and maritime unmanned systems. Aiming at the key problems faced by intelligent unmanned systems and the practical difficulties that will be faced on the battlefield in the future, we analyze the key technologies required for intelligent unmanned systems, including autonomous perception and understanding in complex environments, behavioral decision-making and trajectory planning, autonomous navigation and positioning, multi-scenario autonomous skill learning and intelligent control, unmanned cluster cooperative control, natural human-computer interaction, etc. At the same time, aiming at the problems that will be encountered in the further development of intelligent unmanned systems on the battlefield in the future, we start with individual enhancement and cluster enhancement, and conduct a detailed analysis of the development trends of intelligent unmanned systems. © 2022 Palaeobulgarica. All rights reserved.     

基于蓝墨云班课的《汽车材料》课程优化与实施

随着“互联网+”时代的到来,移动互联网技术给教育领域带来重大的变革,充分合理地应用互联网技术能更好的推动技工院校课程教学改革。蓝墨云班课作为一种基于互联网技术的移动教学平台,将其应用于《汽车材料》课程教学中,能很好地形成线上和线下一体融合的教学模式,提高学生课堂参与度,打造生动、高效、一体的课程学习环境。     

国际枢纽海港的战略内涵及评价指标体系研究

《国家综合立体交通网规划纲要》明确提出我国将着力推进11个国际枢纽海港建设的发展目标，由此为沿海港口的分层次优化发展提出了具体方向。作为更高层次的主要港口，国际枢纽海港肩负着提升我国对外开放水平和全球竞争力、引领区域综合立体交通网络和区域港口群高质量发展的重要使命。基于我国沿海港口的分层次发展特点以及国际枢纽海港提出的时代背景，研究提出国际枢纽海港建设的战略要求、具体内涵和相应的评价指标体系，有利于更好地指导、推动国际枢纽海港的分类特色发展。     

邮轮产业遴选评价体系的构建及其在海南的应用

为科学评价我国邮轮经济总体发展情况，推动“十四五”乃至未来各沿海城市邮轮产业的健康发展，基于邮轮产业统计分类、邮轮属地产业与关联产业的不同内在机理以及产业遴选评价准则等设定，构建考虑邮轮产业与邮轮市场耦合效应的“两阶段多维度”邮轮产业遴选评价体系。研究成果在海南进行具体应用，结合海南经济产业特点和自由贸易港建设要求，明确提出9大类邮轮产业的不同发展定位及各类产业的发展重点，以更好地支撑海南国际旅游消费中心乃至自由贸易港的建设。