铝合金地铁车辆系统动力学特性仿真

地铁车辆系统要求具有良好的动力特性。运用多体系统动力学分析软件ADAMS/Rail建立了铝合金A型地铁动车系统动力学分析模型,进行了稳定性、平稳性和曲线通过能力仿真计算,依据相关标准比较全面地分析其动力学特性。结果表明,该车蛇行运动临界速度远大于车辆设计速度,并且其平稳性和曲线通过能力良好,可满足运行要求。     

一系垂向减振器角度对高速车辆运行性能的影响

利用SIMPACK多体动力学软件建立某高速动车组拖车模型,研究一系垂向减振器纵向、横向倾斜角度对该拖车模型非线性临界速度、直线轨道上的平稳性及曲线通过能力的影响。研究结果表明:一系垂向减振器倾斜角度对车辆稳定性和平稳性影响较大,对曲线通过性能影响较小。     

抗蛇行减振器力学模型及车辆动力学仿真

为了提高车辆动力学计算机仿真精度,研究抗蛇行减振器力学模型及其对车辆动力学性能的影响,基于可压缩流体的压力?流量特性建立了我国某高速动车组抗蛇行减振器非线性力学模型,并对其进行了试验和动力学仿真分析。结果表明：相比传统分段线性模型,抗蛇行减振器非线性力学模型能够同时体现黏性阻尼力和油液被压缩而产生的回复力,仿真计算结果与试验结果吻合良好;基于抗蛇行减振器非线性力学模型计算的临界速度会随踏面等效锥度的增加而先增大后减小,计算的横向平稳性指标较高,且随速度增加而增加的趋势更显著。研究表明,抗蛇行减振器非线性力学模型能够有效提高动力学仿真精度,对车辆的蛇行运动稳定性和横向平稳性有较大影响,但对垂向平稳性和曲线通过安全性的影响较小。     

转向架群配置高速货运动车组车辆曲线通过动态特性研究

为了揭示我国最新研发的转向架群配置高速货运动车组车辆动力学特性,本文综合考虑车辆三系悬挂与转向架群配置的结构和功能特点,基于多体系统动力学理论,建立了转向架群配置的高速货运动车组车辆系统动力学模型。仿真分析了空、重车情况下车辆以不同速度通过曲线的轮轨动态相互作用、车辆运行安全性、车辆运行平稳性等动态性能指标。研究结果表明:①无论空车或重车在本文仿真计算的曲线工况下其各项动力学指标均在限值之内;②轮轨动态相互作用和车辆运行安全性随着速度的增加基本都呈现先减小后增大的趋势,最小值基本都在车速325km/h左右出现;③重车轮轨动态相互作用以及倾覆系数均大于空车,而脱轨系数则是空车大于重车;④车体垂向加速度以及垂向平稳性指标随车辆运行速度变化较小,横向加速度随车速增大而增大,横向平稳性指标则有先增大后减小再增大的趋势,垂向或横向平稳性指标都为优。     

转向架关键参数对地铁车辆提速设计的动力学分析

城市地域规模的扩张及地铁线路长度增加对车辆运营速度提出120km/h的提速要求。以国内某地铁车辆为例,研究转向架关键参数对车辆提速的动力学影响,并给出了提速设计方案。研究结果表明车辆轴距、一系悬挂水平刚度、二系横向减振器阻尼、二系悬挂水平刚度的增大均可以显著提高车辆非线性临界速度。在保证车辆平稳性和曲线通过性能的要求下,给出了提速地铁车辆转向架关键参数设计的方法:在满足车辆稳定性的前提下,车辆轴距、一系定位刚度的设计应考虑车辆曲线通过性能,二系横向减振器和二系水平刚度的设计应充分考虑车辆的平稳性指标。     

基于SIMPACK的轨道车辆动态性能仿真分析

利用多体动力学软件SIMPACK对某型轨道车辆进行整体建模;采用不同速度通过直线轨道线路而获得车辆的线性和非线性临界速度;使轨道车辆通过不同的曲线线路而获得其曲线通过能力;分析了轨道车辆在不同速度下的平稳性指标;采用有限元分析软件ANSYS获得车体的有限元模态文件,输入SIMPACK中获得刚柔耦合的多体动力学模型,并获得车体刚柔耦合的动态性能.     

基于抗蛇行减振器实时特性的车辆动力学性能分析

利用流体建模仿真软件AMESim和多体动力学分析软件SIMPACK分别建立抗蛇行减振器和高速车辆的仿真模型,通过联合仿真比较抗蛇行减振器阻尼分别采用F—v实时特性曲线和等效线性阻尼时车辆的动力学性能,并对比分析车辆在抗蛇行减振器失效、车轮磨耗后车辆的运动稳定性。计算结果表明:采用F—v实时特性曲线时车辆的临界速度高于采用等效线性阻尼的临界速度,且运行平稳性也更好,但二者对车辆的曲线通过安全性的影响不大;减振器失效时,车辆的蛇行运动失稳临界速度显著降低。     

高速动车组轮对质量对车辆动力学性能的影响

为研究高速动车组轮对质量对车辆动力学性能的影响,建立了车辆动力学仿真计算模型,并通过改变其轮对质量在原始值70%~130%范围内变化,得到对应的动力学指标,以揭示轮对质量对车辆动力学性能的影响。计算结果表明:在轮对原始质量附近,随着轮对质量的增加,车辆的临界速度明显降低;车辆的平稳性指标及轮轨垂向力、轮轨磨耗功呈上升趋势;脱轨系数呈现先上升后下降的变化趋势;轮轴横向力和轮重减载率受轮对质量影响不明显。分析结果可以为今后更高性能高速动车组的设计提供一定的理论依据。     

车端纵向减振器对动车组性能的影响

运用动力学软件SIMPACK建立了我国某高速动车组动力学模型,仿真分析了车端减振器卸荷速度、卸荷力对该动车组动力学的影响.这一研究对车端纵向减振器参数的设计及优化具有一定指导意义,即具有一定工程应用价值.动力学仿真结果表明:该动车组稳定性、平稳性随着卸荷速度增加有所恶化,当卸荷速度大于0.005m/s时,卸荷速度对车辆安全性影响较小;稳定性、平稳性随着卸荷力增加有所改善,当卸荷速度大于0.005m/s时,卸荷力对车辆安全性影响不明显.     

100%低地板有轨电车动力学性能研究

利用SIMPACK多体动力学软件建立了100%低地板有轨电车的动力学模型,并对其运行稳定性、平稳性和曲线通过性能进行了动力学仿真计算。分析结果表明,该车具有良好的稳定性、平稳性和小半径曲线通过能力。     

Minimal Realization of Linear Graph Models for Multi-physics Systems

An engineering system may consist of several different types of components,belonging to such physical"domains"as mechanical,electrical,fluid,and thermal.It is t...     

INTEGRAL EQUATION METHOD＇S APPLICATION IN HOLE-EDGE STRESS OF COMPOSITE MATERIAL PLATE WITH DIFFERENT SHAPED HOLES

The strength of composite plate with different hole-shapes is always one of the most important but complicated issues in the application of the composite material. The holes will lead to mutations and discontinuity to the structure. So the hole-edge stress concentration is always a serious phenomenon. And the phenomenon makes the structure strength decrease very quickly to form dangerous weak points. Most partial damage begins from these weak points. According to the complex variable functions theory, the accurate boundary condition of composite plate with different hole-shapes is founded by conformal mapping method to settle the boundary condition problem of complex hole-shapes. Composite plate with commonly hole-shapes in engineering is studied by several complex variable stress fimction. The boundary integral equations are founded based on exact boundary conditions. Then the exact hole-edge stress analytic solution of composite plate with rectangle holes and wing manholes is resolved. Both of offset axis loadings and its influences on the stress concentration coefficient of the hole-edge are discussed. And comparisons of different loads along various offset axis on the hole-edge stress distribution of orthotropic plate with rectangle hole or wing manhole are made. It can be concluded that hole-edge with continuous variable curvatures might help to decrease the stress concentration coefficient; and smaller angle of outer load and fiber can decrease the stress peak value.     

Non-monotonic material contrast in scanning ion and scanning electron images

30 keV Ga⁺ focused ion beam induced secondary electron (iSE) imaging was used to determine the relative contrast between several materials. The iSE signal compared from C, Si, Al, Ti, Cr, Ni, Cu, Mo, Ag, and W metal layers does not decrease with an increase in target atomic number Z₂, and shows a non-monotonic relationship between contrast and Z₂. The non-monotonic relationship is attributed to periodic fluctuations of the stopping power and sputter yield inherent to the ion–solid interactions. In addition, material contrast from electron-induced secondary electron (eSE) and backscattered electron (BSE) images using scanning electron microscopy (SEM) also shows non-monotonic contrast as a function of Z₂, following the periodic behavior of the stopping power for electron–solid interactions. A comparison of the iSE and eSE results shows similar relative contrast between the metal layers, and not complementary contrast as conventionally understood. These similarities in the contrast behavior can be attributed to similarities in the periodic and non-monotonic function defined by incident particle–solid interaction theory.     

Application of Feature Extraction through Convolution Neural Networks and SVM Classifier for Robust Grading of Apples

This paper proposes a novel grading method of apples,in an automated grading device that uses convolutional neural networks to extract the size,color,texture,an...     

分布动态载荷识别的抗噪处理

针对正交多项式频域法在用多种响应对矩形薄板进行载荷识别中抗噪性较差的问题,综合运用平均法、矩阵预处理和奇异值截断法等方法对之进行改善,并引入空间映射的思想,将该方法的应用范围拓展为复杂的模型.利用仿真算例,证实了该方法具有较好的抗噪性.     

Short-Term Relay Quality Prediction Algorithm Based on Long and Short-Term Memory

The fraction defective of semi-finished products is predicted to optimize the process of relay production lines, by which production quality and productivity ar...     

End-to-End Multiview Gesture Recognition for Autonomous Car Parking System

The use of hand gestures can be the most intuitive human-machine interaction medium.The early approaches for hand gesture recognition used device-based methods....     

基于MELTAC-N平台的核电厂安全级DCS环网研究与测试

针对工程实践中环网通讯相关问题的处理缺乏理论基础及国产化安全级DCS平台的开发缺乏成熟经验借鉴问题,对基于MELTAC-N平台核电厂安全级DCS环网的软硬件实现进行了研究。提出了安全级DCS环网双环网冗余设计、光切换开关设计等硬件设计方法,以及以RPR协议为基础,采用全数据收发策略的软件设计方法。在CPR1000安全级DCS平台上对安全级DCS环网的可靠性及实时性进行了评价,并进行了容错能力、响应时间及响应时间稳定性测试验证实验。结果表明,基于MELTAC-N平台安全级DCS环网软硬件设计具有较好的容错能力及响应时间稳定性。     

The laboratory simulation of abrasive wear

Abrasive wear has long been recognised as one of the most potentially serious tribological problems facing the operators of many types of plant and machinery; several industrial surveys have indicated that wear by abrasion can be responsible for more than 50% of unscheduled machine and plant stoppages. Locating the operating point of a tribological contact in an appropriate operational ‚map’︁ can provide a useful guide to the likely nature and origins of the surface degradation experienced in use, though care must be exercised in choosing the most suitable parameters for the axes of the plot. Laboratory testing of materials and simulations of machine contacts are carried out for a number of purposes; at one level for the very practical aims of ranking candidate materials or surface hardening treatments in order of their wear resistance, or in an attempt to predict wear lives under field conditions. More fundamentally, tests may be aimed at elucidating the essential physical mechanisms of surface damage and loss, with the longer term aim of building an analytical and predictive model of the wear process itself. In many cases, component surface damage is brought about by the ingress of hard, particulate matter into machine bearing or sealing clearances. These may be running dry although, more usually, a lubricant or service fluid is present at the interface. A number of standardised wear test geometries and procedures have been established for both two- and three-body wear situations, and these are briefly described. Although abrasive wear is often modelled as following an ‚Archard’︁ equation (i.e. a linear increase in material loss with both load and time, and an inverse dependence on specimen hardness) both industrial experience and laboratory tests of particularly lubricated contacts show that this is not always the case: increasing the hardness differential in an abrasively contaminated lubricated pair may not always reduce the rate of damage to the harder surface.     

ANGULAR DISTORTION ALLOWABLE VALUE AND ASSESS METHOD OF WELD ON COKE TOWER

A graph as the new engineering method for estimate the safety of bulging deformation of coke tower is proposed. Through stresses analysis of circumferential weld of coke tower and comparing the stresses produced by pressure with heat stress of steady state, residual stress, bending stress produced by both itself weight and wind loads, it showed that the stresses produced by pressure on the angle distortion are the main factor of equivalent stress of the combined stress. After comparing four kinds of stress controlling conditions, the relation to stress with depth of angular distortion, grade of curvature of angular distortion and half of region of angular distortion has been inferred. Graph of deformation allowable value of coke tower for different condition by angular distortion and half of region of angular distortion has been plotted. The five steps for its engineering use have been explained. The lighter the grade of curvature is, the larger of bulge allowance, may be, and the bigger of depth of angular distortion may pose too. For the coke tower with a popular structure of Dg 5 400 mm×28 mm, the result by graph is nearly more than the result of two formulas formed by other research, the error is less than 7.0%. But, the graph can be easily applied to different size of angular distortion.