整车刚柔耦合建模及随机激励下的平顺性分析

基于多体动力学理论、有限元及模态综合法,建立了某轿车的整车刚柔耦合动力学模型,其中包括前悬架、转向系等刚体子系统及后悬架柔体子系统.建立B级随机路面模型,采用该数字化试验道路对整车的平顺性进行仿真计算,得到不同车速下的车身质心处垂向加速度以及驾驶员座椅坐垫上方、座椅靠背以及脚支撑面处的加权加速度均方根值.结果表明,所建...     

多编组铰接车辆的平顺性时域分析与优化

为了分析优化多编组铰接车辆的平顺性问题,建立了考虑悬架非线性阻尼特性的n节编组铰接车辆的振动模型,采用粒子群算法对影响车辆平顺性的关键参数(悬架非线性阻尼参数)进行了优化,并提出了一种基于车间铰接约束力补偿和线性二次高斯(linear quadratic Gaussian, LQG)控制相结合的主动悬架控制方法。以车体的垂向、侧倾和俯仰振动加速度均方根作为车辆平顺性关键评价指标,采用B级路面以不同速度对4节编组车辆实施仿真分析。结果表明：随车速增加车辆平顺性变差,且存在首车至尾车车体垂向振动加速度均方根依次变大等振动特点,且通过悬架参数优化与采用主动悬架控制后,车辆平顺性得到明显提高——车辆在垂向、侧倾和俯仰方向的振动加速度均方根分别减少了48.29%,24.79%和54.44%。     

两种装甲车辆座椅动态舒适性比较分析

针对乘员反映的某型装甲车辆行驶过程中座椅,尤其是座椅靠背不舒适的问题,在车辆行驶状态下以座椅-靠背处、座椅支撑面为测点,对车长位原座椅以及另一拟更换安装座椅分别进行了随机振动测量试验;并在采用GB/T 13441.1—2007规定的方法处理试验结果数据的基础上,通过振动总量及频谱分析比较了两种座椅的动态舒适性。弥补了以往座椅振动试验研究中仅针对座椅支撑面进行测量评价,而未考虑座椅-靠背、座椅坐垫支撑面振动对舒适性综合影响的不足,为该装甲车辆座椅系统选择提供了依据。     

汽车弹性元件对平顺性的影响分析及试验优化

基于Matlab/Simulink应用环境,建立1/4车辆三自由度平顺性模型,对随机路面输入下的汽车平顺性进行仿真。应用参数敏感度理论,分析悬架弹簧刚度、悬架橡胶件垂向刚度、座椅刚度和轮胎刚度对座椅和地板垂向加速度均方根值的影响。根据仿真分析结果,对某款轿车橡胶元件进行了试验优化。仿真和试验结果表明:改变橡胶元件刚度可以有效地提高汽车平顺性。     

基于虚拟样机技术的摩托车平顺性分析

应用ADAMS／view建立摩托车的刚柔混合体模型,并对其进行动力学仿真,得出垂向振动加速度。对垂向振动加速度进行数据处理,得到垂向振动加速度功率谱密度函数,并利用加速度加权均方根值为评价指标,对摩托车的平顺性进行评价研究。结果表明,摩托车刚柔混合体模型更接近实际,可以应用于开发阶段摩托车平顺性的分析预测。     

路面随机激励下康复机器人轮椅的抑振解析

为了有效抑制随机路面激励下康复机器人轮椅的振动,提出了一种抑制参数解析优化方法.将康复机器人轮椅的坐垫及轮胎视为具有刚度和阻尼的减振元件,建立了人体-机器人轮椅垂向振动模型;以路面不平顺随机激励作为振动模型的典型输入,推导了人体振动加速度频响函数及方均根响应解析式,并提出了振动响应系数,进而揭示了轮胎减振系统阻尼比及坐垫减振系统阻尼比对频响函数及响应系数的影响规律;基于响应系数,创建了人体-机器人轮椅抑振参数的解析优化模型.结果表明,通过解析优化模型所得坐垫及轮胎最优阻尼与数值模拟优化结果的相对偏差分别为0.3%和0.6%.模型的正确性通过实例优化及数值模拟得到了验证.     

基于虚拟样机技术的汽车平顺性仿真研究

以某双横臂悬架汽车为研究对象,运用虚拟样机技术,建立前悬架虚拟样机模型.通过虚拟仿真,得到其前轮定位参数,揭示其运动学规律.基于ADAMS/Car建立整车仿真模型;建立粗糙水泥路面随机激励及脉冲路面激励,并分别进行汽车平顺性仿真.得到相应的人体振动加权加速度均方根值和座椅处的最大垂向加速度,分别对随机路面激励和脉冲路面激励下的汽车平顺性进行评价.结果表明:随机路面激励下汽车具有较好的平顺性,脉冲路面激励下对乘员健康无危害.     

结构参数对汽车平顺性影响的研究

掌握汽车行驶平顺性的评价指标和人体对振动反应的感觉界限;掌握汽车振动系统物简化方法,了解汽车平顺性的影响因素。     

汽车悬架性能评价研究

汽车行驶平顺性和操纵稳定性评价方法制定是否合理,直接影响对汽车悬架性能的评价,对汽车生产企业有重要指导作用。根据国家相关标准,分别讨论了汽车行驶平顺性和操纵稳定性评价方法;在此基础上,提出了一种新的汽车悬架的评价方法和评价指标。针对某一具体车型,通过测量获得实车参数,以ADAMS/car进行了仿真试验分析。按照提出的汽车悬架的评价方法进行评价。根据汽车平顺性评价的结果,针对某工况下平顺性评分较低,用ADAMS/Insight对悬架相关参数进行正交优化试验;按照优化结果改进实车悬架参数,对比优化前后该车操稳性、平顺性道路试验结果,提出该车型悬架性能改进建议。     

全地形车平顺性客观评价

为弥补目前国内外全地形车舒适性评价方法的空缺,研究分析了全地形车的实际振动特点,依据ISO2631、ISO5349标准,提出了全地形车客观评价方法.该方法利用三轴向总加权加速度均方根值评价全地形车手把处和座位处的振动.对几款全地形车进行了道路试验和台架试验,二者的试验结果比较吻合,说明该评价方法能够很好的反映振动对人体的影响.     

Markedness and its Interpretation in Language Use

Language markedness is a common phenomenon in languages, and is reflected from hearing, vision and sense, i.e. the variation in the three aspects such as phonology, morphology and semantics. This paper focuses on the interpretation of markedness in language use following the three perspectives, i.e. pragmatic interpretation, psychological interpretation and cognitive interpretation, with an aim to define the function of markedness.     

Features of Women's language

Language is a means of verbal communication. People use language to communicate with each other. In the society, no two speakers are exactly alike in the way of speaking. Some differences are due to age, gender, statue and personality. Above all, gender is one of the obvious reasons. The writer of this paper tries to describe the features of women＇s language from these perspectives： pronunciation, intonation, diction, subjects, grammar and discourse. From the discussion of the features of women＇s language, more attention should be paid to language use in social context. What＇s more, the linguistic phenomena in a speaking community can be understood more thoroughly.     

低渗透非均质砂岩油藏启动压力梯度研究

理论推导与室内实验相结合,建立了低渗透非均质砂岩油藏启动压力梯度确定方法。首先借助油藏流场与电场相似的原理,推导了非均质砂岩油藏启动压力梯度计算公式。其次基于稳定流实验方法,建立了非均质砂岩油藏启动压力梯度测试方法。结果表明:低渗透非均质砂岩油藏的启动压力梯度确定遵循两个等效原则。平面非均质油藏的启动压力梯度等于各级渗透率段的启动压力梯度关于长度的加权平均;纵向非均质油藏的启动压力梯度等于各渗透率层的启动压力梯度关于渗透率与渗流面积乘积的加权平均。研究成果可用于有效指导低渗透非均质砂岩油藏的合理井距确定,促进该类油藏的高效开发。     

On Tragic Consciousness In The Works By Ernest Hemingway

As an American modern novelist who were famous in the literary world, Hemingway was not a person who always followed the trend but a sharp observer. At the same time, he was a tragedy maestro, he paid great attention on existence, fate and end-result. The dramatis personae's tragedy of his works was an extreme limit by all means tragedy on the meaning of fearless challenge that failed. The beauty of tragedy was not produced on the destruction of life, but now this kind of value was in the impact activity. They performed for the reader about the tragedy on challenging for the limit and the death.     

Achieving Unusual States of Matter Under High Pressure

正The periodicity of the elements and the non-reactivity of the inner-shell electrons are two related principles of chemistry,rooted in the atomic shell structure.Within compounds,Group I elements,for example,invariably assume the+1 oxidation state,and their chemical properties differ completely from those of the p-block elements.These general rules govern our understanding of chemical structures and reactions.Using first principles calcula-     

Exchange-Correlation and Electronic Excitation Energies from Pairing Matrix Fluctuations

We have developed an adiabatic connection to formulate the ground-state exchange-correlation energy in terms of pairing matrix linear fluctuations.This formulation of the exchange-correlation energy opens a new channel for density functional approximations based on the many-body perturbation theory.We illustrate the potential of such approaches with an approximation based on the particle-particle Random Phase Approximation(pp-RPA).This re-     

Density Functional Theory for the Response of Periodic Systems to Electric Fields Based on the Vector Potential Approach

正The electronic and nuclear(structural/vibrational)response of 1D-3D nanoscale systems to electric fields gives rise to a host of optical,mechanical,spectral,etc.properties that are of high theoretical and applied interest.Due to the computational difficulty of treating such large systems it is convenient to model them as infinite and periodic(at least,in first approximation).The fundamental theoretical/computational problem in doing so is that     

On the Thermodynamic Limit for Responses to Static Electromagnetic Fields

For molecular systems,the quantum-mechanical treatment of their responses to static electromagnetic fields usually employs a scalar-potential treatment of the electric field and a vector-potential treatment of the magnetic field.Although the potential for each field separately is associated with the choice of an(unphysical)origin,the precise choice of the origin for the electrostatic field has little consequences for the results.This is different for the     

Call for Papers

<正>"The Journal of Shanghai Normal University:Mathematics"is published by Shanghai Normal University as regular issues of The Journal of Shanghai Normal University each year from 2014 in English.The editors-in-chief of the issues are professors Yuhao Cong and Maoan Han.The Journal of Shanghai Normal University was started in 1958 with     

Journal of Donghua University ( English Edition) Contents of Volume 31

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