飞机刹车系统先进技术研究与发展

针对多电/全电飞机的发展趋势和现代飞机起飞重量大、着陆速度高的特点,提出了飞机刹车系统防滑控制、全电刹车、刹车材料等先进技术的重点研究方向。首先介绍了飞机刹车系统的组成及其基本工作原理,然后分别从刹车控制系统、防滑控制理论、刹车材料技术3个方面对其发展过程及研究现状进行了总结。最后根据现代飞机制动特点,分析了以上3个重要技术目前存在的问题,并对未来飞机刹车系统的发展趋势进行了展望。     

飞机全电刹车系统滑移率约束反演滑模控制

针对滑移率控制中要求保持刹车工作点的稳定性问题,提出基于障碍Lyapunov函数的反演滑模控制方法并应用于飞机全电刹车系统.考虑机电作动器的非线性特性,建立系统的状态空间模型并简化为严格反馈形式,将刹车系统的控制稳定性问题等效描述为含输出约束的系统镇定问题.根据反演控制思想,采用障碍Lyapunov函数方法获得刹车压力控制律,实现对滑移率的边界约束,并设计无抖振非奇异快速终端滑模控制器应用于机电作动机构,实现对参考刹车压力的快速跟踪.通过Lyapunov方法证明闭环系统稳定性,HIL实验结果表明控制策略的有效性.     

大摩擦力矩下电液伺服系统高精度控制与实验分析

为了实现大摩擦力矩中空液压马达系统高精度跟踪控制,提出了一种基于滑模状态观测器的变结构控制策略,分析了滑模变结构控制规律和滑模状态观测器的理论与实现方法,采用LuGre动态摩擦模型和滑模观测器实现了非线性摩擦力矩的动态补偿.实验结果表明：在超低速、大摩擦力矩存在的情况下,所提出的控制策略实现了非线性电液伺服系统的高精度轨迹跟踪控制.     

基于DSP的飞机防滑刹车系统测试装置

介绍了基于DSP（TMS320LF2407A）和触摸屏MT-500系列（MT-506SV3）的飞机防滑刹车系统测试装置。该测试装置能够在不同温度环境下检测防滑刹车控制盒的工作寿命参数及防滑刹车系统相关附件的性能参数,并通过USB总线把检测结果送给上位机进行分析,为科学评价防滑刹车控制盒整体性能提供了科学依据。     

无人驾驶机器人机械腿非线性模糊自适应反演滑模控制

为了实现无人驾驶机器人机械腿位置精确跟踪及提高车速跟踪精度,针对机械腿受到的非线性干扰,提出了一种基于非线性干扰观测器的机械腿模糊自适应反演滑模控制方法.首先,通过对机械腿机构操纵踏板时的位置运动分析,建立了机械腿运动学模型,构建了考虑运动副非线性摩擦的机械腿动力学模型,描述了机械腿关节间摩擦力矩与相对速度之间的关系,求得了摩擦参数.接着,设计了油门/制动机械腿切换控制器和非线性干扰观测器.最后,针对观测误差以及其他不确定干扰,设计了模糊自适应反演滑模控制器,进行了李雅普诺夫稳定性分析.实验结果表明,所提方法有效削减了控制输出的抖振,且相较于未对摩擦进行补偿的情况,机械腿位置最大跟踪误差从5.5×10~(-2) rad减小为1.1×10~(-3) rad,最大车速跟踪误差从2.21 km/h减小为1.91 km/h.基于干扰观测器的机械腿模糊自适应反演滑模控制方法能够有效提高机械腿跟踪精度与车速跟踪精度.     

基于半车模型的ABS滑模变结构控制仿真研究

由于汽车轮胎动力学的非线性,对防抱死制动系统采用了滑模变结构控制方法进行控制,滑模控制能较好地解决非线性系统的控制问题,但其固有的抖动会影响控制效果.本文采用一种基于指数趋近律的滑模控制方法,针对两轮车辆的防抱死制动系统设计了滑模控制器,并在Matlab/Simulink里进行了仿真.仿真结果表明了该策略的可行性和有效性,并且能较好的抑制控制系统的抖动现象.     

某型飞机“刹车故障指示灯”虚警现象原因及改进措施

电子防滑控制盒是飞机防滑刹车系统中的主要控制部件。针对某型飞机在刹车过程中经常出现的防滑故障指示灯虚警现象,进行了试验验证,找出了故障原因,并进行了设计改进,经过装机试验,效果明显,证明了改进方案的可行性。     

基于奇异摄动理论的机器人关节控制研究

针对机器人柔性关节存在位置控制精度低的问题,在考虑关节内部非线性摩擦和外界扰动等因素的情况下,建立柔性关节动力学模型,提出基于奇异摄动理论的干扰观测器滑模控制方法,利用该控制方法对关节控制系统进行Lyapunov稳定性分析和MATLAB仿真.结果表明,基于奇异摄动理论的干扰观测器滑模控制方法能够减小关节内部非线性摩擦和...     

铁道车辆制动系统防滑控制仿真与试验研究

通过建立铁道车辆单轮对运动学模型、轮轨蠕滑力模型、制动过程的制动力开环与闭环控制模型,分析了单轮对制动工况下的防滑控制仿真方法.针对电空直通制动系统防滑单元,基于DSHplus软件建立了气路仿真模型与防滑控制策略仿真模型,通过与Matlab联合仿真,分析了电空直通制动系统防滑单元的气路特性与控制参数的选择,研制了制动防滑单元并进行了相关试验,结果表明,该仿真模型可用于模拟轮对制动过程的滑行工况,可用于防滑单元的集成设计与参数优化.     

飞机防滑刹车控制系统发展概况

介绍了飞机防滑刹车控制系统的基础知识和分类,研究总结了飞机防滑刹车控制系统的国内外发展现状和发展方向。     

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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