美国及中国军用无人机的新发展与性能分析

文章介绍了美国军用无人机的一些新发展以及中国军用无人机的发展情况,并对各自发展的方向和趋势作了简要概括。通过对中美几种军用无人机性能参数的对比和分析,指出了中国军用无人机的差距。     

A Research on the Braking Control Strategy with Energy Consuming Braking for Power-split HEV

通过分析电制动过程中能耗制动系统的工作和控制过程,为功率分流混合电动车提出了一种包含能耗制动的机电联合制动控制策略,采用试验数据和数学模型相结合的方式建立了整车仿真模型,选用典型城市驱动循环工况进行了仿真.结果表明,提出的制动控制策略能保证整车制动过程中蓄电池的充电安全性,并可高效地回收制动能量.     

地基土抗剪强度与极限平衡条件的评价分析

在确定地基土的抗剪强度的基础上 ,运用材料力学中平面应力状态的理论对无粘性土和粘性土均进行了极限平衡条件的评价分析 ,运用该分析方法进行工程实例计算 ,计算结果表明该方法较准确、可靠。     

Locomotive dynamic performance under traction/braking conditions considering effect of gear transmissions

Traction or braking operations are usually applied to trains or locomotives for acceleration, speed adjustment, and stopping. During these operations, gear transmission equipment plays a very significant role in the delivery of traction or electrical braking power. Failures of the gear transmissions are likely to cause power loses and even threaten the operation safety of the train. Its dynamic performance is closely related to the normal operation and service safety of the entire train, especially under some emergency braking conditions. In this paper, a locomotive–track coupled vertical–longitudinal dynamics model is employed with considering the dynamic action from the gear transmissions. This dynamics model enables the detailed analysis and more practical simulation on the characteristics of power transmission path, namely motor–gear transmission–wheelset–longitudinal motion of locomotive, especially for traction or braking conditions. Multi-excitation sources, such as time-varying mesh stiffness and nonlinear wheel–rail contact excitations, are considered in this study. This dynamics model is then validated by comparing the simulated results with the experimental test results under braking conditions. The calculated results indicate that involvement of gear transmission could reveal the load reduction of the wheelset due to transmitted forces. Vibrations of the wheelset and the motor are dominated by variation of the gear dynamic mesh forces in the low speed range and by rail geometric irregularity in the higher speed range. Rail vertical geometric irregularity could also cause wheelset longitudinal vibrations, and do modulations to the gear dynamic mesh forces. Besides, the hauling weight has little effect on the locomotive vibrations and the dynamic mesh forces of the gear transmissions for both traction and braking conditions under the same running speed.     

土建工程中的土坡稳定性分析

在分析土建工程中土坡失稳原因的基础上,分析无粘性土及粘性土土坡稳定,针对目前粘性土土坡稳定分析的几种方法,重点讨论了条分法,另外还介绍用查表分析法来确定土质边坡坡度。     

基于蚁群聚类的路面识别分析方法

道路是城市的重要基础设施．路面状况的鉴定与评价直接关系到公路的养护决策,是一项至关重要的工作．本研究将蚁群聚类算法应用于路面识别领域,提出一种基于蚁群聚类优化的路面识别分析方法,将此方法运用于路面识别系统．该系统由数据采集、数据预处理和蚁群聚类优化3个模块组成,其中蚁群聚类主要提取了纵轴方向的3个特征属性,通过不断更新聚类中心产生的信息素矩阵,并通过分类器进行路面分类．实验结果表明：蚁群聚类优化具有全局收敛以及启发式学习等优点,运算效率高,路面识别准确率达到95.3％,验证了此方法的有效性．     

以规范的管理方式和创新的工作思路建立海上搜救应急管理体系

“以最快捷的方式获取最准确的信息情报，以最科学的决策制定最完善的施救方案，以最有效的手段配备最精干的搜救力量，以最满意的社会效果回馈最关切的社会期待。”这是交通部副部长徐祖远对中国海上搜救中心提出的工作方法和目标，同时也是广大涉海人民群众对交通部海上搜救工作的切实需要。     

海船闸气幕防咸设计

为指导船闸气幕防咸设计,本文将经典Abraham方法和Keetels数据进行比较.结果发现,Abraham方法偏保守.基于Keetels数据,本文提出一种新的半经验公式,以获得更准确的供气量.     

高压旋喷技术在船坞坞口基坑施工中的应用

以扬州大洋造船有限公司船坞坞口止水帷幕工程为例,介绍了高压旋喷技术在该工程的应用。介绍了工程地质和水文地质后,介绍了高压喷射注浆机理和特性。介绍旋喷止水帷幕的参数设计方法,包括帷幕深度、旋喷桩孔位布置方式、施工参数。对高压旋喷桩的关键施工工序质量控制和喷射质量的检查也进行了较为细致的讨论。从施工效果来看,该工法应用于深、软地基防水防渗工程是成功的。