Multi-objective aerodynamic optimization design of high-speed train head shape

To improve the aerodynamic performance of high-speed trains (HSTs) running in the open air, a multi-objective aerodynamic optimization design method for the head shape of a HST is proposed in this paper. A parametric model of the HST was established and seven design variables of the head shape were extracted. Sample points and their exact values of optimization objectives were obtained by an optimal Latin hypercube sampling (opt. LHS) plan and computational fluid dynamic (CFD) simulations, respectively. A Kriging surrogate model was constructed based on the sample points and their optimization objectives. Taking the total aerodynamic drag force and the aerodynamic lift force of the tail coach as the optimization objectives, the multi-objective aerodynamic optimization design was performed based on a non-dominated sorting genetic algorithm-II (NSGA-II) and the Kriging model. After optimization, a series of Pareto-optimal head shapes were obtained. An optimal head shape was selected from the Pareto-optimal head shapes, and the aerodynamic performance of the HST with the optimal head shape was compared with that of the original train in conditions with and without crosswinds. Compared with the original train, the total aerodynamic drag force is reduced by 2.61% and the lift force of the tail coach is reduced by 9.90% in conditions without crosswind. Moreover, the optimal train benefits from lower fluctuations in aerodynamic loads in crosswind conditions.     

高速铁路运营过程中的关键问题：轮轨磨耗等

随着高速铁路运营里程和列车运营速度的不断增长,出现了一些和列车轨道耦合大系统密切相关的关键科学和技术问题。这些问题不仅影响到列车的运行品质,甚至威胁到安全运行,是当前高速铁路运用和发展中急需解决的问题。本文系统描述了高速铁路在运营过程中所出现的一些关键科学和技术问题,并述评了全世界有关这些问题的研究进展、现状和不足之处,提出了今后有利于认识和解决这些问题的发展方向。在长期高速运营的铁路大系统环境中,这些问题的形成的机理、发生、发展过程和预防措施的研究,需要从列车／轨道耦合大系统运营环境（速度、路况、气候和运用维修）、系统的自身参数匹配、材料选用和运营成本等全面系统考虑,并从理论、技术、工艺、监控和维修等方面解决。     

一种高速列车-轨道三维空间耦合动力学模型

研究目的：基于车辆-轨道耦合动力学理论分析方法,建立一种高速列车-轨道三维耦合动力学模型,并明确列车-轨道耦合模型与单节车辆-轨道耦合模型在高速列车-车九道耦合动力学性能分析中的差异。创新要点：建立一种高速列车-轨道三维耦合动力学模型,模型中考虑列车的纵向动力学行为以及车间连接装置对列车中不同车辆动态响应的影响,并基本明确完善的列车-轨道耦合模型在高速列车-轨道耦合动力学性能分析中的重要性。重要结论：单节车辆-轨道耦合模型会过高地估计高速列车在运营过程中的振动响应和动力学性能指标,而完善的列车-轨道耦合动力学模型的计算结果则更加接近实际情况。     

A numerical approach to the interaction between airflow and a high-speed train subjected to crosswind

Aerodynamic forces and dynamic performances of railway vehicles are coupled and affected by each other. On the one hand, aerodynamic forces change the displacements of a train. On the other hand, displacements affect aerodynamic forces. Based on vehicle-track coupling dynamics and aerodynamics, a numerical approach to the interaction between airflow and a high-speed train is presented in this paper. Aerodynamic forces and dynamic performances of a high-speed train subjected to crosswind were numerically simulated. Results showed that the interaction between airflow and a high-speed train has a significant influence on displacements and aerodynamic forces of the head coach. Therefore, it is necessary to consider the interaction between airflow and a high-speed train subjected to crosswind.     

Dynamic analysis of a high-speed train operating on a curved track with failed fasteners

A high-speed train-track coupling dynamic model is used to investigate the dynamic behavior of a high-speed train operating on a curved track with failed fasteners. The model considers a high-speed train consisting of eight vehicles coupled with a ballasted track. The vehicle is modeled as a multi-body system, and the rail is modeled with a Timoshenko beam resting on the discrete sleepers. The vehicle model considers the effect of the end connections of the neighboring vehicles on the dynamic behavior. The track model takes into account the lateral, vertical, and torsional deformations of the rails and the effect of the discrete sleeper support on the coupling dynamics of the vehicles and the track. The sleepers are assumed to move backward at a constant speed to simulate the vehicle running along the track at the same speed. The train model couples with the track model by using a Hertzian contact model for the wheel/rail normal force calculation, and the nonlinear creep theory by Shen et al. (1984) is used for wheel/rail tangent force calculation. In the analysis, a curved track of 7000-m radius with failed fasteners is selected, and the effects of train operational speed and the number of failed fasteners on the dynamic behaviors of the train and the track are investigated in detail. Furthermore, the wheel/rail forces and derailment coefficient and the wheelset loading reduction are analyzed when the high-speed train passes over the curved track with the different number of continuously failed fasteners at different operational speeds. Through the detailed numerical analysis, it is found that the high-speed train can operate normally on the curved track of 7000-m radius at the speeds of 200 km/h to 350 km/h.     

高速铁道车辆风致安全性研究

研究目的：随着世界高速铁路网的不断扩张,高速列车的风致安全性成为高速铁路系统中的关键科学问题之一。本文利用车辆-轨道耦合动力学理论分析方法,确定强横风作用下高速铁道车辆的安全运行区域,为强风地带高速列车的安全控制提供依据。创新要点：首次提出了考虑多种影响因素和脱轨评价指标的高速列车脱轨安全域分析方法,并运用到了高速铁道车辆风致安全性研究中。研究方法：基于车辆-轨道耦合动态响应及多种安全性评价指标得到横风作用下高速铁道车辆的安全运行区域和脱轨区域。重要结论：铁道车辆安全性评价指标中,轮重减载率对横风激励最为敏感,其确定了强风作用下高速车辆安全运行区域的边界。     

Structure optimization of the dispensing house in a combustion train for a thermal bake-out aluminum reduction cell

1. Introduction The bake-out and start-up technologies of aluminum reduction cells is one of the important factors affecting the service life of cells. The service life of cells is of importance to economic benefit in aluminum reduction cells production. Especially for big prebaked cells, the study on bake-out and start-up is even more important. The present methods of bake-out include aluminum fluid bake-out, coke granule bake-out and graphite bake-out [1,2]. The disadvantage of aluminum ba…     

Multi-objective genetic algorithm for the optimization of road surface cleaning process

INTRODUCTION The technology of using waterjet for cleaning is an important problem in engineering. There are many researches on using waterjets for cleaning. Most of them are focused on the relationship between clean-ing parameters and cleaning effectiveness (Louis and Schikorr, 1982; Summers, 1982; Liu et al., 1999; Taggart et al., 2002). However, few researches are related to the optimization of cleaning parameters to improve cleaning performance even if it is very cru-cial for fully…     

基于粗糙集的多目标类Bayes粗糙集模型

介绍了两个目标类的决策信息系统中各目标类的Bayes粗糙集模型,并将这一模型推广到具有多目标类的情形.最后讨论了该模型的相关性质,计算实例表明该模型是有效的.     

综合评价方法在防砂方式优选中的应用

为解决油田疏松砂岩油藏油井出砂问题,发展了多种防砂技术,然而每种防砂方式有各自的适应性及优缺点．针对目前油井防砂方法优选存在的问题和不足,拟采用模糊数学原理,初选技术上可行的防砂方法,然后利用经济评价模型给出经济有效的防砂方法,再结合两种方法的计算结果,进行综合评价,优选出技术上科学合理、经济高效的防砂方法．为油田防砂方法的选择提供决策依据．应用综合评价方法对两口井进行了计算分析,通过综合评价模型给出了适合该井的技术合理、经济有效的防砂方法;另外,当模糊数学评价模型与经济评价模型计算结果有差别时,要结合综合因素进行选择．     

列车荷载对下穿盾构隧道影响的模型试验

为研究地面线路运营对下穿盾构隧道结构的影响规律,基于相似比理论建立室内大型试验模型,模拟上部列车荷载作用下土层及其内部盾构隧道结构的受力变形过程,总结变形规律。结果表明,模型试验能够较好地反映外部荷载影响下土层以及内部盾构隧道结构的受力和变形特性;地表列车荷载在土层传递过程中,同一层面上沿地面线路方向的土压力大于两侧土压力,远离线路的地层受列车荷载影响相对较小,同一竖向截面土压力变化量由上至下逐渐减小,即外部荷载对浅层土的影响明显大于深层土;盾构隧道在地表列车行驶过程中,环向出现背车面受拉迎车面受压的受力特性,呈斜向压扁,纵向应变从中间交叉点向盾构隧道两侧逐渐减小,呈下凹压弯;盾构隧道埋深越小,受地表荷载影响越显著,增大一倍埋深对应纵向应变最大值减小约44.5%。     

TS型模糊PID控制器设计的改进

提出了一种TS型模糊PID控制器的改进算法。通过对两种TS型模糊PID控制器进行分析，指出存在的问题并提出改进方法，引入非线性量化因子，优化隶属函数，引入积分环节，降低模糊控制器的维数，简化规则等，使改进后的模糊PID控制器在规则少、参数简化、参数调解难度降低的基础上获得更好的控制效果。     

构图视觉下多媒体课件优化设计探析

多媒体技术的发展极大地改变着当今教与学的方式,多媒体画面语言形式成为时下司空见惯的知识传递方式。分析多媒体课件的一般要求,结合多媒体画面语言理论和信息化传播理论,文章从构图角度系统地分析多媒体课件设计的优化过程。     

猪的最佳销售时机研究

在猪的养殖和销售过程中,科学的了解猪的生长规律及市场变化规律,并选择猪的最佳销售时机,这是获得最大利润的前提。将建立猪的生长模型及饲养成本模型,并用Matlab求解出猪的最佳销售时机,所得结果更科学更合理。     

双冷源温湿度独立控制空调系统设计优化研究

从熵态视角对空调负荷进行划分,基于双温冷源空调系统基础上,根据不同新风处理方法,探讨设计参数选取及负荷计算。通过系统优化遵循“高熵负荷用高温冷源消除,低熵负荷用低温冷源消除”的原则,除高温冷源降温外,提出串联高、低温冷源的除湿循环,建立双温冷源能耗模型,数值模拟计算得到最佳除湿、除热冷源有效温度。     

课程体系优化的系统观及系统方法

提出了一个课程体系优化的系统结构模式 ,从外部环境与内部结构的相互作用上区分了课程体系改革及优化必须考虑的因素 ;给出了一个课程体系优化的系统工程程序 ,重点论述了如何从“课程体系→课程群→主干课程”实现课程体系的递阶控制及三级优化思路 ;给出了课程体系优化评价的指标体系及评价模型 ,并以此完成高师地理学专业课程体系优化设计。     

基于改进BESO算法的集材绞盘机卷筒优化设计

通过修正材料插值模型和引入应力均方差作为性能收敛指标,改进了基于von Mises应力的双向渐进结构拓扑优化(Bi-directional Evolutionary Structural Optimization, BESO)方法,并结合Abaqus有限元软件及MATLAB语言编程实现了该算法;在此基础上,优化设计了集材绞盘机摩擦卷筒,得到不同材料体积分数、不同旋转周期数时,摩擦卷筒的最优拓扑结构,在减轻质量的同时,降低了应力集中水平。优化结果对实现集材绞盘机摩擦卷筒轻量化设计具有工程指导意义。     

粒子群优化算法发展综述

粒子群优化（PSO）算法是一种源于人工生命和演化计算理论的优化技术．PSO通过粒子搜寻自身的个体最好解和整个粒子群的全局最好解来更新完成优化．该算法原理简单，所需参数枝少，易于实现，目前已经应用到很多领域．文章阐述了基本PSO的原理。给出了各种改进技术，并展望了PSO的发展方向。     

Inverse displacement analysis of the general six degree-of-freedom serial robot based on optimization method

The paper presents a new solution of inverse displacement analysis of the general six degree-of-freedom serial robot. The inverse displacement analysis of the general serial robot is transformed into a minimization problem and then the optimization method is adopted to solve the nonlinear least squares problem with the analytic form of new Jacobian matrix. In this way, joint variables of the general serial robot can be searched out quickly under the desired precision when positions of the three non-collinear end effector points are given. Compared with the general Newton iterative method, the proposed algorithm can search out the solution when the robot is at the singular configuration and the initial configuration used in the optimization method may also be the singular configuration. So the convergence domain is bigger than that of the general Newton iterative method. Another advantage of the proposed algorithm is that positions of the three non-collinear end effector points are usually much easier to be measured than the orientation of the end effector. The inverse displacement analysis of the general 6R (six-revolute-joint) serial robot is illustrated as an example and the simulation results verify the efficiency of the proposed algorithm. Because the three non-collinear points can be selected at random, the method can be applied to any other types of serial robots.     

DyCl3-KCl和DyCl3-CaCl2体系相图的热力学优化计算

1 Introduction Molten salts are considered to be used as fluid tar-gets in the nuclear incineration of transuranic elementswith proto accelerators .The molten salts are also usedas the media in high temperature chemical reprocess-ing of spent nuclear fuel of fast reactors .The phase di-agrams of rare earth metal halides in combination withalkali metal halide systems are of pri me i mportance inapplication. The thermodynamic properties and phase diagramsof the DyCl3-MClnsystems ( M =alkali or…