中等视场大相对孔径水下两档变焦光学系统

研究了水下两档变焦光学系统的设计方法并给出了具体设计实例。采用轴向移动变焦方式,变焦过程中相对孔径保持不变,相对孔径为1/1.4,系统变焦比为2,在水下的宽视场角为60,°有效焦距3.6 mm,用于大范围内搜索目标;窄视场角为20°,有效焦距7.2 mm,用于对目标进行具体分析。在空间42 lp/mm处的宽视场和窄视场的光学传递函数值均大于0.4,成像质量较好。既满足了水下成像对大相对孔径和较大视场的要求,又能够在大范围内搜索目标,小范围内对具体目标进行分析,满足实际应用的需要。     

机翼变形误差对发射后截获性能的影响研究

研究了机翼变形角误差对空空导弹发射后截获性能的影响.根据某型导弹挂机后计算的载机机体坐标系与导弹弹体坐标系的相对角误差量,仿真计算了机翼变形角误差对导弹发射后截获概率的影响.仿真结果表明,机翼变形角误差对导弹发射后截获性能影响大,必须对其进行补偿,否则载机在大机动情况下发射导弹,导弹将不能截获目标.并据此提出了对机翼变形角误差的补偿方法和解决途径.研究结果对空空导弹的工程研制具有参考价值.     

机载预警雷达牵引模式的IRST探测效能分析

机载预警雷达牵引红外搜索跟踪系统(IRST)探测是同平台多传感器协同的一种重要工作模式。为定量评估该模式对IRST探测效能的影响,以IRST探测概率作为评估指标,建立多个瞬时视场下的成功牵引概率数学模型,计算在不同雷达工作模式下满足一定成功牵引概率的IRST搜索视场范围,推导IRST的探测概率与作用距离、脉冲积累之间的关系式。仿真结果表明,在保证成功牵引概率为0.99的前提下,雷达在高精度测量模式下的牵引效果最佳,使IRST的搜索区域缩小为原来的1/180,时间节约效率为99.4%,加快了对目标的截获过程。节余的时间可用来对目标进行脉冲积累,当积累2个脉冲时,在其最大作用距离处所对应的探测概率由无积累时的0.5提升到0.985 3,从而显著提升其探测效能。     

防空火力压制任务中反辐射无人机搜索航路优选

反辐射无人机在执行对敌防空火力压制任务时典型的搜索航路有跑道形和"8"字形2种。建立"视场覆盖率"这一指标来衡量两典型搜索航路对目标雷达的压制效果,实现对这两典型搜索航路的优选。为此,首先通过建立数学模型的方法分别求得两种搜索航路的视场覆盖率,然后分别分析了无人机转弯半径、航路规划空间直线长度对两搜索航路视场覆盖率的影响,最后综合考虑了无人机导引头水平机械视场周期扫描对两搜索航路视场覆盖率理论计算值的影响。计算结果表明:在航路规划空间大小、无人机转弯半径一定的情况下,两典型搜索航路的视场覆盖率均低于50%,但"8"字形搜索航路视场覆盖率明显高于跑道形搜索航路,对目标雷达的压制效果更好。     

遥感卫星对区域目标可见窗口的半解析快速算法

遥感卫星对区域目标的可见窗口计算是卫星观测任务的重要基础,高精度、高效率的求解算法对卫星观测任务规划具有重要意义.该文提出了一种针对区域目标快速计算可见窗口的半解析方法.该方法利用空间几何关系,将所有卫星视场投影与区域目标的边界描述为大圆弧或普通圆弧,得到区域边界相交判定方法;针对圆锥和矩形视场,得出解析判断可见性的条...     

考虑导引头视场角和落角约束的制导方法

针对空地武器采用最优弹道成型制导律进行大落角攻击时易造成导引头跟踪误差角大于其视场角而丢失目标的问题,提出一种满足导弹导引头视场角约束和落角约束的制导方法.基于线性化模型和小角假设,得到了导引头跟踪误差角的解析表达式,分析了影响导引头跟踪误差角的因素及最大跟踪误差角的取值范围.在此基础上,针对不同空地武器提出了通过改变末制导初始弹目视线角或放松落角约束的方式满足导引头视场角约束的制导方法,并给出了初始弹目视线角的取值原则及最大允许落角的计算方法.通过仿真校验,证明了导引头跟踪误差角的解析解的正确性及制导方法的可行性.      

TDI光敏探测器扫描方向瞬时视场角的计算方法

TDI光敏探测器多用于扫描成像,评价其成像系统的分辨率常用扫描方向的瞬时视场角(IFOV)衡量 .文章首先分析了TDICCD成像仪瞬时视场角的计算方法,并在对红外TDI探测器和TDICCD的结构进行了比较后,得出红外TDI探测器瞬时视场角的计算方法,此方法也可应用于计算垂直于扫描方向的瞬时视场角.     

基于光谱辐射信息的高温目标图像识别

利用光学及辐射度学的基本原理，对成像过程进行理论分析，建立了照明条件下识别视场中高温目标的数学模型，揭示了影响识别效果的各物理因素。通过对这些物理因素进行分析，指出“切割波段”可有效提高信噪比，将高温目标识别出来，并通过液晶光阀予以技术实现。实验结果验证了该方案的可行性及有效性。     

随机噪声调频信号带宽分析

随机噪声雷达由于具有低截获率,抗干扰能力及电磁兼容能力等一系列特点,得到了广泛的重视.介绍了一种随机噪声调频雷达信号,对它的自相关函数和频谱函数进行了详细的推导.通过理论分析和计算机仿真总结了不同条件下随机噪声调频信号带宽的计算方法.利用对带宽的分析,进一步讨论了带宽对信号分辨率和截获率的影响.仿真结果表明,噪声调频信号易于实现宽带特性,并且在大带宽的条件下具有良好的分辨率和低截获性能.     

基于粗糙熵和目标威胁等级的多传感器管理方法

随着现代化武器平台的快速发展,多传感器管理在信息融合系统中所占据的地位越来越重要,因此,需要对有限的传感器资源进行科学合理的管理,提高防空作战能力.针对多传感器资源管理优化问题,分析了粗糙熵的定义,提出了基于粗糙熵和目标威胁等级的多传感器管理方法.该方法通过计算传感器对目标的粗糙熵,获得每个传感器对每个目标最大的信息增益,以此作为代价函数,考虑目标的威胁等级,利用线性规划思想进行多传感器对多目标的优化分配,实例分析表明了该方法的有效性.     

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     

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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