An improved algorithm for fluid-structure interaction of high-speed trains under crosswind

Based on the train-track coupling dynamics and high-speed train aerodynamics, this paper deals with an improved algorithm for fluid-structure interaction of high-speed trains. In the algorithm, the data communication between fluid solver and structure solver is avoided by inserting the program of train-track coupling dynamics into fluid dynamics program, and the relaxation factor concerning the load boundary of the fluid-structure interface is introduced to improve the fluctuation and convergence of aerodynamic forces. With this method, the fluid-structure dynamics of a high-speed train are simulated under the condition that the velocity of crosswind is 13.8 m/s and the train speed is 350 km/h. When the relaxation factor equals 0.5, the fluctuation of aerodynamic forces is lower and its convergence is faster than in other cases. The side force and lateral displacement of the head train are compared between off-line simulation and co-simulation. Simulation results show that the fluid-structure interaction has a significant influence on the aerodynamics and attitude of the head train under crosswind conditions. In addition, the security indexes of the head train worsen after the fluid-structure interaction calculation. Therefore, the fluid-structure interaction calculation is necessary for high-speed trains.

     

缺陷产品召回物流形成机制与实践策略分析

针对缺陷产品召回成本高、效率低的问题,提出了缺陷产品召回物流理论,即通过召回物流的效率来实现产品召回的社会效益.通过构建社会化召回物流网络,完善物流企业产品召回处理功能,加强召回过程产品信息与物流信息共享等策略,实施召回物流管理.实施召回物流有助于维护消费者权益、降低企业召回成本、实现缺陷产品回收与资源再利用.     

瓮福磷矿选矿厂精矿仓设计

瓮福磷矿选矿厂精矿仓首次采用网架式地面矿仓，造价低，空间利用率高，设备运行平稳可靠，操作灵活方便，工作环境好。超长梭式胶带布料机的设计也是成功的。     

基于Logistic回归惩罚函数的遗传位点分析

探讨将基于惩罚函数的变量选择方法应用到遗传位点分析.以2016年9月16日的全国研究生数学建模竞赛B题的数据为例,首先对每个位点的碱基对(A、T、C、G)编码方式数值化处理,最后用数值化后的数据进行建模,并将单变量选择Logistic SCAD、组变量选择Logistic Group SCAD模型和双层变量选择Logistic cMCP模型定位到与遗传性疾病显著相关的遗传位点,分别与出题者提供的标准答案进行对比,结果显示双层变量选择Logistic cMCP模型能够准确的定位到与遗传性疾病显著相关的遗传位点.因此将其运用到具有遗传性疾病和性状的遗传位点分析是值得研究的.     

基于渐开线齿轮范成仪的改进设计

根据渐开线廓范成仪的功能和原理,把老式范成仪的手动操作改为电子控制自动操作,使操作精确方便,经实际使用效果很好,为制造自动式渐线线齿轮范成仪提供参考.     

基于RFID的监狱智能定位系统的设计与实现

为解决在押犯人管理困难的问题,该文介绍了一种基于射频识别技术的CC1110 RSSI定位系统。系统主要由腕带标签、读卡器、无线中继和服务器组成。标签主要负责对读卡器发送相关信息,读卡器负责接收标签的数据并转发给无线中继,中继通过以太网把读卡器传送过来的数据发送给服务器,服务器负责对数据的处理、分析并进行相关管理操作。该系统结构简单、硬件成本较低、易部署、适应性较强。实际测试表明,该系统能够用于监狱在押人员的定位,降低非视距误差。     

安徽中小企业发展现状及创新路径研究

近几年,在政府大力扶持之下,安徽中小企业快速发展,已成为推动经济持续、健康发展的重要力量,但在发展过程中也存在一些不容忽视的问题。本文从企业总量、地区分布、企业产值、所有制类型等方面对安徽中小企业进行调查,在此基础上分析安徽中小企业在发展过程中存在的问题,并提出相应的建议和对策,对丰富中小企业发展理论、制定安徽中小企业发展政策具有一定的意义。     

Enhanced luminescence and thermal stability of (Sr,Ca)AlSiN3:Eu2+ via superficial organic carbon modification

The Eu²⁺-activated nitride phosphors have been widely used in solid-state lighting, but the applications in high-power white-light-emitting diodes (wLEDs) field require higher thermal stability of luminescent materials. The oxidation of Eu²⁺ and the damage of nitride host in the Eu²⁺-activated nitride phosphors are the two crucial reasons for the luminescence loss while operating. A superficial organic carbon modification is performed on the red-emitting (Sr,Ca)AlSiN₃:Eu²⁺ phosphor via the incorporation of organic carbon by solution mixing and thermal post-treatment under the N₂-H₂ atmosphere. After the superficial organic carbon modification, the oxidation of Eu²⁺ and the formation of impurity phases on the phosphor surface are effectively reduced. When the superficial organic carbon modified sample was treated in the 2 wt.% sucrose solutions, the relative brightness is strengthened by 2.15%, the thermal quenching characteristic is improved by 8.9% at 300℃, and the aging test results show an excellent thermal stability. All above indicate that the superficial organic carbon modification is a promising technique to enhance the thermal stability of analogous Eu²⁺-activated nirtide phosphors.     

基于步进传动标记机系统的设计

论述了标记系统组成原理，简要地介绍了计算机与系统之间接口模块及步进电机驱动器的设计。最后，给出了本系统采用的逐点比较法直线插补器的实现方法。     

钢的回火过程中应力演化的数值模拟

本文提出了一种模拟钢的回火过程中应力演化的数学模型。其中着重进行了蠕变方面的试验研究。在淬火过程数值模拟基础上，用据此模型开发的有限元软件对２６Ｃｒ２Ｎｉ４ＭｏＶ钢圆筒形试件的回火过程进行了计算。结果表明，由本模型预测的回火效果与实测吻合较好。此外还计算分析了回火规范对残余应力的影响，进一步验证了模型的有效性。