拉氏方程与键图在机电系统动力学上的应用

本文首先讨论并对比了拉氏方程与键图在机电系统动力学上应用的两种不同形式。并提出了:①关于运用 AFS 形式时非保守广义力(或广义电动势) E_i 与键图间的关系;②机电综合系统中计算广义力(或广义电动势)E_(?)的改进方法。本文的论述将使拉氏方程与键图应用于工程实践时更觉方便,物理概念更为清晰。     

广义负载模拟器的广义力误差最小轨迹规划

研究了基于结构化空间刚度的广义负载模拟器的轨迹规划问题,建立了主从式双并联广义负载模拟系统的数学模型.以广义力为优化目标,提出一种广义力误差最小的轨迹规划方法,并将轨迹分解为静态最优轨迹和动态补偿轨迹.最优轨迹中根据虎克定理给出广义力到位姿的映射关系,补偿轨迹在最优轨迹离散点附近线性化动力学方程,用于抵消惯性载荷的影响.仿真结果表明,该方法可用于空间加载轨迹的高精度实时生成,其广义力误差小于0.9‰,对实际工程具有重要意义.     

关于广义力的一点讨论

在理论力学的教学中,广义力对于初学者是比较抽象的概念,本文通过对广义坐标的讨论,说明了广义力的物理意义。并从广义力的物理意义出发,讨论了广义力的求解法。通过这样的讨论,在教学中,初学者对广义力有了比较明确的概念。     

非线性非自治非保守阻尼系统的第二类Lagrange方程

基于非自治有阻尼系统推导了第二类Lagrange方程,使用虚功原理,给出了广义力的求解方法,广义力由广义保守力、广义耗散力、除广义保守力和广义耗散力以外的对应于广义坐标的广义力这3部分组成.利用第二类Lagrange方程推导了一级倒立摆非保守有阻尼系统的运动微分方程和状态空间模型.用数值分析软件Matlab 6.5对状态空间模型进行了线性二次调节器最优控制.     

U(1)群规范势的动力学理论

本文对U(1)群规范势进行了探讨,将它分为场强势A_β~F及相位势A_β~α,A_β~α可以用一个等价的惯性力场描述.文中给出包含A_β~α的拉氏量及方程,讨论了几个特例,并推广到非阿贝尔群的情况.     

基于最大车速的广义力跟驰模型

为了更有效地模拟城市交通流，尤其是城市交叉口交通流的运行状况，在研究跟驰状态中车辆行驶特性的基础上，考虑车辆行驶的最大限制速度，提出了一种基于最大车速的广义力模型。将该模型与Helbing—Tilch广义力模型分别用于模拟车辆经过信号交叉口的动态运动，并采用实际道路上车辆的跟车数据仿真跟车情况。结果表明，该模型不仅消除了Helbing—Tilch广义力模型存在的停车间距过大问题，而且仿真效果更接近实际的交通流特性。     

基于广义流和广义力的河流能耗率推导

基于非平衡态热力学理论中局域熵产生和能耗函数的关系,以及能耗函数可以写作不可逆过程中每个广义流与其相应的广义力的乘积之和,构造了河流的广义力和广义流,推导出河流的能耗函数数学表达式.通过对能耗函数做体积分,进而推导出河流的能耗率.从而避开使用众多复杂的非平衡态热力学和高等流体力学公式,过程简便且易于理解.     

利用等价无穷小代换求极限应注意的问题

利用等价无穷小代换求极限可以简化计算.现在使用的高等数学和数学分析教材中,往往只给出积、商运算中等价无穷小因子的代换法则,对利用等价无穷小代换求极限的适用情况却未能提及,这一方面限制了此方法的使用,另一方面缺乏明确的代换法则,在使用时易出现错误.本文讨论了极限运算中等价无穷小量的代换问题,给出了相应的代换条件和应用实例.     

基于运动跟踪的分布式驱动电动汽车操纵稳定性控制

提出一种分布式驱动电动汽车操纵稳定性控制策略.该策略采用分层控制的结构,上层为广义力计算层,设计基于前轮转角的前馈控制,提高横摆角速度稳态增益,同时考虑外界扰动和建模不确定性,设计积分抗饱和滑模变结构控制算法跟踪参考横摆角速度,提高车辆瞬态响应.下层为广义力分配层,考虑到实际行驶状况的复杂以及路面状况、车辆质心侧偏角难以实时获取,设计基于稳定性优先的规则分配机制.实车试验结果表明,该控制策略能有效提高车辆的操纵稳定性.     

广义力法公式及其证明

在传统的力法分析中,无论是力法基本方程的建立还是方程中系数和自由项的求解,都要求在同一基本结构上进行,而在广义力法中,可以同时基于两个不同的基本结构求解超静定问题.对n次超静定结构,本文以引理形式给出了广义的力法方程和叠加公式并给出了证明,当选取的两个基本结构完全一致时,给出的广义力法公式退化为传统的力法方程和叠加公式.本文工作有助于人们对力法的进一步认识.     

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