汽车用碳纤维复合摩阻材料的摩擦磨损特性研究

在采用正交设计优化碳纤维复合摩阻材料的基础上，针对汽车制动器衬片的实际工况，研究了碳纤维复合摩阻材料的摩擦磨损特性及磨损机制分析了碳纤维含量、强度及表面状态等对磨损机制的影响。研究结果表明，碳纤维复合摩阻材料的磨损性能、工作寿命及抗热衰退性能均明显高于传统的石棉摩阻材料。     

The receiving of chirp signals with frequency invariant beam response

1 Introduction1 The sensor array and the correlative signal processing methods have been adopted for the ability improvement of detection and orientation in modern sonar systems, and beamforming is a widely used tool in sensor array signal processing for …     

Analysis on the Effects of Overloading on the Mechanical Properties of Tunnel Structures in the Silty Ground --A Case Study of Sutong River-crossing GIL Utility Tunnel北大核心CSCD

Based on the Sutong GIL utility tunnel project, which is constructed by the shield machine under the river, and as for the overloading problem at the river bank slope during operating period, the refined threedimensional finite element model was established to study the deformation and cracking characteristics of the tunnel segment structure under different forms of overloading. The evolution laws of section convergence, joint opening and structural stress were analyzed, and the structure damage mechanisms were revealed under conditions of large area loading and local loading. The surface-surcharge control standard was proposed. For the big diameter shield tunneling crossing the silty clay, the research results show that: (1) the deformation failure process is divided into three stages under large area loading condition, taking the design load and compressive yield of rebars inside haunch as the critical points respectively. The first stage is characterized by the elastic stress, the second stage is in plastic state with fracture, and the third stage is accelerating deformation and instability stage. The vertical convergence is 110.5 mm with no opening of joints when rebars are yielded; (2)the deformation failure process under local loading condition is also divided into elasticity, plasticity and instability stages, taking the design load and tensile yield of rebars outside haunch as the critical points respectively. The vertical convergence is 152.6 mm with joint opening of 4.36 mm; (3) the early-warning values of additional stress on the ground under conditions of large area loading and local loading are 110 kPa and 70 kPa respectively. © 2018, Editorial Office of "Modern Tunnelling Technology". All right reserved.     

我国铁路货运集中化推进模式的研究

铁路广泛实行货运集中化,成为铁路运输组织现代化的主要发展趋势之一。在研究国内外铁路货运集中化的基础上,分析铁路货运集中化的经济效益,提出了我国实施铁路货运集中化的阶段推进模式。     

混合式教学模式下的大学英语课程思政教学设计与实践 ——以兰州大学《大学英语(3/4)》课程为例

本研究以兰州大学针对非英语专业大二学生开设的《大学英语（3/4）》为例,基于理论分析及调查问卷结果,探索并分析了混合式教学模式在大学英语课程教学设计中的应用,聚焦大学英语课程中思政元素的融入模式及效果。教学实践表明,线上线下教学的有机融合既能保证学生的语言学习需求,又为实施课程思政教学提供了保障。在混合式教学模式下进行大学英语课程思政教学要求教师发挥主导作用,不断深入发掘教材中的思政元素、对课程进行精细设计并为学生提供优质的学习资源,以学生为中心利用线上线下学习模式凸显其主体性,才能取得最佳的教学效果。     

西部大开发广西铁路发展的思考

世纪之交,世纪之梦,党中央、国务院已经作出了西部大开发的战略决策.西部大开发,将给广西带来发展社会生产力,加快工业化、城市化、现代化进程的千载难逢的历史性机遇.西部大开发,广西大开发,广西铁路怎么办?这是摆在我们铁路建设和管理者面前的重要课题.     

U341E型自动变速器电磁阀的检测与故障诊断

该文以U341E型自动变速器电磁阀为例,叙述了电磁阀的结构特点、检测标准等。作者结合工作实践中遇到的行车故障,进行反复的车辆路试,掌握第一手的故障现象、故障特征,巧妙的运用电磁阀的工作规律,进行列表式的推理分析,最终清晰准确的诊断由电磁阀引发的故障。     

旭普林型无碴轨道施工工艺研究

为指导郑西客运专线无碴轨道施工,根据旭普林无碴轨道技术交流的情况,认真分析交流资料,结合中国国情,初步总结出旭普林无碴轨道施工工艺流程,并提出需要进一步解决的问题,为施工单位前期研究提供参考。     

谈船舶超载的成因及对策

在水上运输过程中,因船舶超载运输而导致的沉船事故时有发生。如何遏制船舶超载,维护航行秩序,是水上安全监督工作的热点、难点。本文拟就结合在实际工作中的一些做法及体会,探讨船舶超载的成因及对策。     

A system dynamics approach to land use/transportation system performance modeling Part I: Methodology

This paper presents a system dynamics approach to simultaneous land use/transportation system performance modeling. A model is designed based on the causality functions and feedback loop structure between a large number of physical, socioeconomic, and policy variables. The model consists of 7 sub‐models: population, migration of population, household, job growth‐employment‐land availability, housing development, travel demand, and traffic congestion level. The model is formulated in DYNAMO simulation language, and tested on a data set from Montgomery County, MD. In Part I: Methodology, the overall approach and the structure of the model system is discussed and the causal‐loop diagrams and major equations are presented. In Part II: Application, the model is calibrated and tested with data from Montgomery County, MD. Least square method and overall system behavior are used to estimate the model parameters. The model is fitted with the 1970–80 data and validated with the 1980–1990 data. Robustness and sensitivities with respect to input parameters such as birth rate or regional economy growth are analyzed. The model performance as a policy analysis tool is examined by predicting the year by year impacts of highway capacity expansion on land use and transportation system performance. While this is a first attempt in using dynamic system simulation modeling in simultaneous treatment of land use and transportation system interactions, and model development and application are limited due to data availability, the results indicate that the proposed method is a promising approach in dealing with complex urban land use/transportation modeling.