锅炉汽包液位自动控制调节

水位保护的作用是当汽包水位超越高限或低于低限时,迫使锅炉保护系统切换主燃料,紧急停炉,以避免发生设备损坏事故。所以汽包液位自动调节效果必须要求准确、可靠。     

一类区间切换系统的鲁棒稳定性

讨论了一类区间切换系统的鲁棒稳定性.区间切换系统是一类含有不确定参数的切换系统.作为一个切换系统,标称系统的稳定性决定了这类区间切换系统的鲁棒稳定性.充分利用结构特点,通过标称系统各部分的稳定性获得这类系统的鲁棒稳定性.当标称系统的各子系统均渐近稳定时,给出区间切换系统在任意切换下渐近稳定的条件.进一步,在标称系统的各子系统都不渐近稳定的情形下,利用凸组合技术,讨论了实现区间切换系统在某一切换律下的渐近稳定性.     

相关度为1时非线性切换系统的稳定化

对一般(非切换)系统,在零动态稳定的条件下,容易实现系统的稳定化.本文将此结果推广至切换系统.即当各子系统具有相同相关度1且在零动态不稳定情形,讨论切换系统在任意切换下以及某种切换率下的稳定化问题.通过变换方法分别给出非线性切换系统在任意切换下和某种切换信号下稳定化的充分条件.     

一类切换系统的最优控制及其优化算法

在切换序列和切换次数未知的情况下,研究了一类切换系统的最优控制问题.首先,以切换系统为基础,通过构造嵌入系统,研究了嵌入系统的最优性条件和切换系统次优解的构造方法;其次,讨论了两个系统的关系,给出并证明了嵌入系统最优解是切换系统最优解的充分性条件;最后,根据充分性条件,构造了求解切换系统最优或次优解的优化算法.数值结果验证了算法的有效性.     

时滞切换正系统的切换齐次协正Lyapunov函数方法

正系统是一类特殊系统——如果初始状态非负, 则其状态始终位于正象限. 切换系统是混杂系统的主要分支之一. 作为两类系统的结合体, 切换正系统已经迅速获得控制界的大量关注. 主要研究时滞切换正系统的稳定性问题, 提出了切换齐次协正李亚普诺夫函数方法. 该方法能够有效地降切换系统稳定性判据的保守性. 许多现有结果都是本文主要结论的退化情形.     

时滞切换正系统的切换齐次协正Lyapunov函数方法(英文)

正系统是一类特殊系统——如果初始状态非负,则其状态始终位于正象限.切换系统是混杂系统的主要分支之一.作为两类系统的结合体,切换正系统已经迅速获得控制界的大量关注.主要研究时滞切换正系统的稳定性问题,提出了切换齐次协正李亚普诺夫函数方法.该方法能够有效地降切换系统稳定性判据的保守性.许多现有结果都是本文主要结论的退化情形.     

GMR-1 卫星通信系统中基于判决的切换算法

在卫星移动通信系统中,卫星和用户都处于运动中,当用户穿越波束边界时需要进行切换.切换是卫星移动通信系统中重要的组成部分,切换算法的好坏直接影响移动通信质量.在无线资源受限的卫星移动通信系统中,不必要的切换会造成系统资源浪费.地面和卫星移动通信存在差异,地面移动通信系统中的越区切换算法在卫星移动通信网络中不再适用.针对现有波束切换算法在切换判决时没有考虑当前链路质量,提出一种基于判决的卫星波束切换算法.该算法根据当前链路质量动态地调整切换迟滞值参数的变化,并为不同速度的用户设置不同的切换触发时间.仿真结果表明,与现有的卫星点波束切换算法相比,所提算法能够合理地触发必须切换,避免不必要的切换,从而降低网络的乒乓切换和切换失败率.     

一类模糊切换多模型系统的分段Lyapunov稳定

给出一种新的受控模糊切换多模型系统结构,保证在局部模型切换过程中系统状态轨迹的平滑性.利用分段Lyapunov函数稳定性定理,证明了模糊受控多模型切换系统相邻切换及跳变切换的稳定性条件,在该条件约束下设计的监督机切换序列可以保证受控模糊切换多模型系统的Lyapunov稳定性.     

基于LMI的时滞切换系统的稳定性分析

研究一类子系统为时滞系统的切换系统渐近稳定性问题.以线性矩阵不等式的形式提出了在任意切换信号作用下系统渐近稳定的充分性条件,给出了系统渐近稳定的凸组合条件以及切换信号的选取.仿真实例证明了所设计的切换方案的有效性.     

切换正系统稳定性的新判据(英文)

本文主要考虑了切换正系统在任意切换信号下的稳定性问题. 主要贡献在于以下两点:1、建立了切换正系统稳定性的新的判定准则. 该准则可以视为切换正系统领域已有结果的补充. 2、本文的方法独特,为解决切换正系统领域的其它问题将有很重要的启示作用. 数值例子验证了所得理论结果的正确性和有效性.     

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