低轨星座红外凝视传感器覆盖性能分析

针对低轨星座凝视传感器覆盖问题,首先从理论上分析了最大可探测距离、方位角、俯仰角及轨道高度对单个传感器覆盖性能的影响.然后在典型圆轨道星座下,初步分析了轨道高度、轨道倾角及升交点赤经对星座整体覆盖性能的影响.基于点覆盖数值仿真技术的计算结果表明,覆盖率统计结果规律与理论分析完全一致.     

最大化全移动无线传感器网络寿命的可信信息覆盖重定位算法

针对全移动传感器网络覆盖空洞的修复以及网络寿命最大化问题,研究并设计了一种基于可信信息覆盖模型的传感器节点重定位协议。该协议在可信信息覆盖模型下的信息网格的概念下,设计一种局部信息网格结构,通过使用移动最近的冗余传感器节点修复覆盖空洞区域来维持网络的完全覆盖。仿真结果表明,所设计的协议与现有的协议传感器节点重定位协议相比,可以有效减少重定位的移动能量消耗,明显提升全移动传感器网络的工作寿命。     

一种基于网格划分的虚拟力部署算法的研究

针对移动传感器网络节点自部署的覆盖和能耗等关键问题,对部署区域进行正方形网格划分,结合虚拟力算法,提出了一种基于网格划分的修正虚拟力部署混合算法,并采用网格顺序编号法和网格螺旋编号法两种编号方法,分别对该部署算法的性能进行了仿真分析.仿真结果表明,与原始虚拟力算法相比,所提出的算法能更快更高地提高网络覆盖率;同时相较于顺序编号法,采用螺旋编号法时所提出的部署算法节能性能和能量均衡性能更好.     

TDI-CMOS图像传感器像移降质模型研究

根据TDI-CMOS图像传感器的工作原理和曝光时序,建立了像移作用下传感器的降质模型,并在此基础上,推导了传感器沿轨和跨轨方向线性非正常像移的MTF模型,着重分析了累加级数、行选时间、像素曝光时间和速度同步误差对线性非正常像移MTF的影响.为更好地分析不同像移形式对成像质量的影响,建立了TDI-CMOS图像传感器动态链路仿真模型,对传感器沿轨和跨轨方向存在线性非正常像移情况进行了仿真,并利用刃边法计算降质图像的MTF值.仿真结果表明,沿轨和跨轨方向线性非正常像移MTF不仅与速度同步误差有关系,还与累加级数、行选时间和像素曝光时间有关系.提出的传感器动态链路仿真模型能够用于仿真不同形式的像移对成像质量的影响.     

高架式轻轨车站人员疏散仿真分析

为研究轻轨车站内人员安全疏散过程,制定车站人员疏散方案及优化建筑设计,进一步完善以功能单元为基础的精细网格区域疏散模型与疏散仿真软件.把楼梯视为一个独立的空间单元,将其划分成精细网格,进行网格疏散;加入人员移动余值的概念,使人员运动的连续性与网格模型的个体化优势结合起来.针对重庆市高架式轻轨车站特点进行实地调研,通过问卷调查及现场观测得到了轻轨乘客的一般特性参数及对火灾的反应特性,测试不同类型人员正常行走速度与经验推荐值基本相同.采用改进的区域网格疏散仿真程序对轻轨车站进行了人员疏散仿真研究,将疏散仿真结果与实地观测结果进行了对比,仿真计算与实测的疏散时间基本一致,验证了程序的正确性.     

人造卫星测轨新方法——单位矢量法

根据单位矢量法测轨原理,在人造卫星初轨计算的单位矢量法的基础上,完善了数学模型,改进了计算方法,建立了单位矢量法的从无摄初轨到有摄初轨,从初轨计算到轨道改进的系列算法,研制了融初轨计算和轨道改进于一体的统一测轨方法（PUVM2）.PUVM2方法对5个轨道根数进行了非线性化处理,避免了微分轨道改进时要对所有轨道根数求有摄偏导数的繁复计算,简化了工作环节.大量的仿真和实测计算表明,该方法可以有效地提高轨道半长轴和平纬度角的测定精度,这对卫星测控、轨道预报和空间目标监视都非常有利;该方法适用于不同偏心率轨道的定轨,具有广阔的应用前景.     

一种有向传感器网络改进粒子群覆盖增强算法

优化传感器网络覆盖对于合理分配网络的空间资源、更好地完成信息感知和采集任务、提高网络的生存能力都具有重要的意义。在分析传感器节点有向感知模型的基础上,提出了一种有向传感器网络改进粒子群覆盖增强算法。该算法针对随机部署有向传感器网络,以网络区域覆盖率为优化目标,采用改进的多步式位置可选择更新粒子群优化算法,通过调整传感器节点的主感方向,减少网络感知重叠区和感知盲区,实现覆盖增强。仿真实验表明,该算法简单、高效,优于传统的覆盖增强算法。     

低轨星座传感器实时调度模型

针对低轨星座目标连续跟踪传感器资源调度问题,通过提取跟踪精度、资源松弛度和资源分配均衡因子这三个优化参数,建立了传感器实时调度模型;并通过对跟踪精度及其影响因素的分析,提出了一种基于卫星目标几何关系的简化模型.仿真实验表明,简化模型有效降低了实时调度模型的运算量,且调度传感器对目标的跟踪精度没有明显降低,因而是一种更加高效的传感器调度模型.     

基于集合覆盖的异构有向传感网寿命优化策略

在由感知半径、感知角度和携带能量不同的有向传感器节点组成的异构有向传感器网络中,对满足优先级不同的监测目标有不同覆盖要求条件下的网络寿命最大化问题进行研究。利用集合覆盖的思想,将有向传感器节点划分为满足目标覆盖要求的集合,通过集合之间的切换来达到延长网络寿命的目的。首先证明本文问题是NP-hard问题,然后利用改进的和声搜索算法进行求解,一方面引入带有混沌参数的微分变异因子,改进种群的多样性;另一方面,与模拟退火算法结合增强算法的局部搜索能力。同时为对比算法性能,提出一种贪婪算法。仿真结果显示:较之原始和声搜索算法和贪婪算法,改进和声搜索算法能有效延长网络的寿命,证明了改进算法的有效性。     

GIS空间数据库索引算法的研究与改进

空间数据库的索引技术是提高空间数据库存储效率、空间检索性能的关键技术.迄今人们已经提出了许多空间索引方法,其中网格空间索引数据结构是目前在GIS中被最为广泛采用的一种索引数据结构.网格索引中最大的难点在于确定网格划分的精细程度,网格划分的好坏将对索引数据量和检索效率产生直接影响.针对网格空间索引方法的特点和局限性,我们提出了对地理范围多次划分,划分矩形的长宽取值与空间实体对象直接关联的改进算法.改进后的算法可以减少划分过程中人为因素的影响,增强层次划分的稳定性,提高空间数据的访问效率.     

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.     

An Analysis of Catherine＇s Character——Wuthering Heights

Wuthering Heights, Emily Bronte＇s only novel, was published in December of 1847 under the pseudonym Ellis Bell. The book did not gain immediate success, but it is now thought one of the finest novels in the English language. Catherine is the key character of this masterpiece, because everybody and everything center on her though she had a short life. We can understand this masterpiece better if we know Catherine well.     

Lower Paleozoic oil relationships within Williston Basin, Canada

The Williston Basin is a significant petroleum province, containing oil production zones that include the Middle Cambrian to Lower Ordovician, Upper Ordovician, Middle Devonian, Upper Devonian and Mississippian and within the Jurassic and Cretaceous. The oils of the Williston Basin exhibit a wide range of geochemical characteristics defined as "oil families", although the geochemical signature of the Cambrian Deadwood Formation and Lower Ordovician Winnipeg reservoired oils does not match any "oil family". Despite their close stratigraphic proximity, it is evident that the oils of the Lower Palaeozoic within the Williston Basin are distinct. This suggests the presence of a new "oil family" within the Williston Basin. Diagnostic geochemical signatures occur in the gasoline range chromatograms, within saturate fraction gas chromatograms and biomarker fingerprints. However, some of the established criteria and cross-plots that are currently used to segregate oils into distinct genetic families within the basin do not always meet with success, particularly when applied to the Lower Palaeozoic oils of the Deadwood and Winnipeg Formation.     

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     

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