近场光存储一体化光学飞行头结构设计与特性仿真

设计了一种新型一体化光学飞行头，通过对光学飞行头滑块气浮力分布和飞行姿态(飞行高度、仰俯角和滚动角)的数值仿真分析，对滑块气体轴承表面(ABS)形貌参数进行了优化设计，确定了滑块的主要结构参数．仿真结果表明，所设计的光学飞行头滑块的飞行高度能够在光盘的不同半径处保持在43-44nm之间，符合近场光存储系统的信号读写要求．该光学飞行头具有良好的机械性能和光学性能，可在近场光存储系统的读写过程中获得稳定的飞行高度和高信噪比的光学信号．     

基于Simulink的偏置式曲柄滑块机构运动仿真

针对偏置式曲柄滑块机构,建立了速度和加速度的闭环矢量方程,使用Simulink对偏置式曲柄滑块机构进行了运动学仿真,得到了连杆及滑块的运动曲线．使用这种方法可以方便的观察到机构运动特性的变化,为后续的动力学分析提供了基础．     

2(3PUS+S)并联机构驱动部件振动模型分析

为了改善一种新型的2(3PUS+S)并联机构的驱动部件对整个并联机构运动稳定性的影响,对该并联机构的驱动部件振动模型进行了深入的分析。先通过混合法建立驱动部件的轴向振动模型和扭转振动模型,再通过拉格朗日方程法得到扭转和轴向振动模型的固有频率和振型,然后将数据导入MATLAB软件中进行编程计算、数值模拟仿真。结果表明:轴向振动固有频率随着滑块的位置升高而减少,对于扭转振动固有频率,低阶固有频率随着滑块的位置升高而增加,高阶固有频率则呈现和轴向振动固有频率相似的规律。可见通过对驱动部件振动模型的分析,对提高整个并联机构运动稳定性具有指导性意义。     

质量矩拦截器末制导复合控制方法研究

针对在大气层内飞行的质量矩拦截器,研究了其变质心控制问题.在建立内部含有1个滑块和8个姿控发动机的拦截器制导运动模型的基础上,描述了滑块与弹壳之间的相对移动对系统产生的耦合影响.设计了一种复合控制律来给出滑块的期望位置和姿控发动机的开关指令,并通过对轴向滑块与姿控发动机的协调控制,快速补偿了法向需用过载.讨论了滑块运动对系统性能的影响,并进行了系统的稳定性分析.仿真结果表明该方法能有效实现拦截器末段的制导控制.     

基于Simulink的运动仿真在机械原理课程设计中的应用

在机械原理课程设计中，通常需要进行机构的运动分析计算。以六杆机构为例建立了闭环矢量方程，介绍了仿真初始条件的确定，并基于Matlab/Simulink对其进行了运动学仿真，得到六杆机构的运动参数以及滑块的速度、加速度。仿真过程简单，改变了传统的图解法设计，为机械原理课程设计的改进提供了一种新的思路。     

振动引起的界面切向相对运动对摩擦的影响

为了研究接触界面振动对摩擦的影响, 自主设计实验装置, 以在振动台上匀速滑动的滑块为对象, 采用理论与实验相结合的方法, 分析法向振动和切向振动引起界面切向运动减摩的机理。实验结果表明, 振动台的法向振动和切向振动经常同时存在。当界面振动, 且滑块与振动台之间的切向相对速度方向不变时, 滑块受到的平均滑动摩擦力与无振动时相同, 没有减摩作用; 当滑块与振动台之间切向相对速度的方向发生周期性变化或存在stick-slip (黏滑)时, 与无振动时相比, 滑块的平均滑动摩擦力有明显的减摩作用。根据Coulomb摩擦定律建立动力学模型进行仿真, 仿真结果与实验结果非常吻合, 说明在界面运动为已知的条件下, Coulomb摩擦模型能够反映界面间的摩擦作用。实验和仿真结果表明, 当法向振动和切向振动同时存在时, 振动引起的界面切向相对运动造成摩擦力方向的周期性变化或stick-slip是减摩的主要原因。     

机电系统协同仿真在实践教学中的应用

在机电系统计算机控制技术实践教学中,为了直观表达及对比系统的运动特性,采用Matlab与ADAMS软件协同仿真方法,以曲柄滑块机构为例进行了建模和仿真。通过系统仿真平台的直观建立和仿真结果的可视化,帮助学生加深对机电系统计算机控制及仿真技术的理解和认识,激发学生的学习兴趣,提高其创新能力和工程实践能力。     

拖钩刨刨头转角的运动学模型

为了研究刨煤机的动力学行为，提高刨头的设计质量，以拖钩式刨煤机为例，对刨头作运动学分析，得到各转动角度与刨头结构和受力之间的关系。将欧拉角应用于刨头的有限转动分析，通过对两组角度表达式进行模拟，建立了刨头有限转动的运动学方程以及各个转角的数学表达式，求解得到了各个转角以及角速度之间的关系。由欧拉角的变化规律，可以确定刨头的姿态，从而能够实现刨头姿态的准确控制。     

基于MATLAB的曲柄滑块机构动力分析

以某曲柄滑块机构为研究对象,当曲柄滑块机构在运行过程中,其运动质量所产生的往复、旋转惯性力和反转矩等,都会随着曲柄滑块机构的曲轴转角的变化而产生相应的变化。本文基于MATLAB软件平台,首先对曲柄滑块机构进行受力分析,并建立曲柄滑块机构的数学模型,在MATLAB中设置曲柄滑块机构各项参数进行动力学仿真,分析各杆件的运动状态,为曲柄滑块机构的运动分析提供一种新思路。     

基于Adams的高速多连杆压力机驱动机构运动学分析

针对高速多连杆压力机驱动机构,首先采用模块化方法建立其数学模型,得到驱动机构的运动学方程;然后根据运动学方程,利用Matlab仿真得到滑块的位移、速度、加速度曲线;再应用动力学分析软件Admas对驱动机构进行运动学分析;最后对比两种分析结果,表明该驱动机构的可行性。     

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     

An affordable accurate evaluation of the binding conformations predicted by molecular docking studies in bio-system

Franck-Condon factors bridge the gap between theoretical modeling and experimental observations for molecular electronic spectroscopy and electron transfer.Under the displaced harmonic oscillator approximation,multidimensional Franck-Condon factors are decomposed into a product of many one-dimensional(1D)Franck-Condon(FC)factors,and each 1D-FC factor is associated with one Huang-Rhys factor that determines the leading contribution of     

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