船舶电力系统直流网络绝缘状态监测系统研究

本文讨论了船舶电力系统直流网络绝缘状态监测研究的需求和必要性,分析了目前国内主要船舶的直流网络现状及其绝缘监测需求,讨论了国内外绝缘监测技术现状,最终确立了适应我国情况的直流网络绝缘监测设计方案,并通过仿真验证了其测量原理的正确性。     

日本对华投资对中日货物运输的影响

海外投资促进了贸易的增长,带来了资本输出国与资本输入国的贸易结构的变化。本文分析了日本对中国的投资结构,并对对华投资及其引发的相关货运问题进行了探讨。     

运输需求与成本不确定下的枢纽港选择

针对轴辐式网络中的枢纽港选择问题，在集装箱航运网络中，考虑运输需求与成本的不确定，根据数据变化规律，构建多个模型. 根据轴辐式网络的运输环节，使用成本函数表征枢纽港间运输成本，构建枢纽港选择的确定性模型；基于此，针对航运需求的离散特性，构建需求不确定的随机模型进行枢纽港选择；基于运输成本难以预测的特点，结合实际数据，使用极小极大值法构建成本不确定的枢纽港选择模型；然后，结合两者构建运输需求与运输成本同时不确定的枢纽港选择模型. 采用欧洲集装箱运输网络实际数据对模型进行验证，求解各因素不确定下枢纽港选择的最优方案，并针对结果进行对比分析，为班轮公司优化航线提供参考.     

高速铁路泡沫轻质土路基帮宽施工关键技术

针对既有高速铁路路基帮宽工程中的差异沉降和偏移难题,提出了浇筑泡沫轻质土的解决方案。从泡沫轻质土路基结构设计和湿密度设计2方面来控制沉降变形,根据现场具体情况分析水化热产生的原因并加以控制,提出远距离浇筑的具体办法和措施。施工前材料进场时、施工中计量和浇筑过程中、硬化后均应对泡沫轻质土进行质量检验和验收。     

Development and prospects of key technology for submarine atmospheric environment control北大核心CSCD

Air regeneration, harmful gas purification and atmospheric composition monitoring are the key technologies of submarine atmospheric environment control systems. After years of development, China has made great progress in such systems, which have developed from ensuring the safety requirements of submariner and equipment operation to ensuring the health of submariner and reliability of system for long-term underwater operation. This paper reviews the development history of submarine atmospheric environment control technologies and introduces their future development prospects. The developers of integrated atmospheric environment control technology should learn from foreign submarine and aerosphere equipment technologies, which aim to support long-term submerged operation and comfort demands, and better adapt to future submarine technology development and evolving mission, in order to constantly enhance the level of submarine cabin air quality of the Chinese navy. © 2022 Journal of Clinical Hepatology. All rights reserved.     

轨道交通轮轨接触面材料性能与轮轨切向接触阻尼关系研究

为准确计算轮轨切向接触阻尼,基于接触阻尼理论,考虑轮轨材料的弹塑性变形和车轮表面粗糙度,采用有限元法,将轮轨材料的接触面进行离散;基于罚函数面-面接触算法定义轮轨接触,建立轮轨粗糙表面接触有限元简化模型;通过间接输入实际车轮表面硬度数据并且加载位移载荷来计算轮轨切向接触阻尼损耗因子和轮轨切向接触阻尼.仿真结果表明:轮轨切向接触阻尼损耗因子随着法向载荷、摩擦系数和车轮表面硬度的增加而减小,而粗糙度对其影响不大;轮轨切向接触阻尼与法向载荷、材料表面的摩擦系数及材料表面的硬度呈正相关;随着摩擦系数的增大,轮轨切向接触阻尼先增大后趋于稳定;轮轨切向接触阻尼与运行里程数并非呈现单调性变化.因此,当考虑轮轨材料表面粗糙度微观结构时,更能够反映实际情况.     

新能源车型热管理控制策略逆向解析方案

热管理控制策略是新能源汽车能够安全稳定运行的关键,好的控制策略有助于降低能耗,延长车辆使用寿命以及提高乘员舱的舒适性等优点。为了更好的借鉴优秀车型的热管理控制策略,提出了一种热管理控制策略的逆向解析方案,可以利用测试和破解信号等手段,分析获取车辆的热管理控制策略。这有助于缩短开发周期,优化原有车型的控制策略,降低项目开发成本。     

水力式升船机阀门选型可行性研究

输水阀门是水力式升船机的核心部件,对其进行专门的选型研究十分必要且意义重大。基于景洪水力式升船机原型试验成果,综述常用闸阀门的应用情况及水力学研究进展,分析得出:基于成熟的阀门防空化技术,可以适当降低阀门的空化性能要求、选用锥阀替代活塞式调流阀进一步降低造价。论证了水力式升船机阀门选型研究的可行性。     

Three Dimensional Numerical Simulation Study on the Tensile Test of the Embedded Components in Segment Joints of Deep Buried Storage and Drainage Shield Tunnels北大核心CSCD

The numerical simulation was carried out based on tensile test of the embedded components in segment joints of the deep buried storage and drainage shield-driven tunnel in Shanghai in order to study the numerical approach for mechanical analysis of segment joints of the tunnel. Using the concrete damage plasticity model and nonlinear springs, the 3D refined numerical model was established, in which the embedded components with complex geometries and the bond-slip behaviors between the concrete and bars were taken into consideration. Three kinds of embedded component models with different degrees of refinement were established and simply loaded. By comparing the calculation results and considering the spent time and the accuracy of calculation, the simplified form of the embedded components used in the overall model was determined. Nonlinear springs between anchor bars and concrete were set in the model in order to simulate the bond-slip behavior between them. In addition, two contrast models were also established using binding constraint and face-face contact constraint between concrete and anchor bars respectively. The three types of models were loaded in accordance with the test conditions. Comparing the results of the numerical calculation with the test results, it is shown that the "nonlinear spring model", which takes the bond-slip behavior into consideration, is more consistent with the test results than the "face to face contact model" and "binding model". And the model also reflects the failure mode very well. It indicates that the three dimensional refined modeling method used in this paper is applicable for similar tensile tests. © 2018, Editorial Office of "Modern Tunnelling Technology". All right reserved.     

基于CAN总线的摊铺机自动找平控制系统

为提高路面摊铺平整度,研究了一种基于CAN总线的多点(多探头)非接触式摊铺机自动找平系统,给出了系统总体结构、CAN节点的硬件电路及软件主要流程,采用多重滤波方法进行数据处理,滤除摊铺机作业过程中偶然因素造成的跳点数据,提高系统的抗干扰性能。采用该找平系统对单探头和多探头找平方式进行了对比试验,结果表明多探头方式找平效果优于单探头方式;与接触式自动找平系统对比实验表明采用该找平系统中面层平整度平均值较接触式提高了3.2%,上面层提高了7.8%。