提高雷达高度表测高精度的方法研究

讨论了雷达高度表脉冲回波受地形、地貌、植被及雷达本身参数(波束、发射功率、频率、天线及指向误差角ξ)影响的问题,给出了一种在飞行实验中运用高速A/D直接测量雷达高度表回波波形数据,通过对飞行试验数据积累、分析、处理及计算机仿真,获得了高度表测高修正模型的方法．     

提高雷达高度表测高精度的方法研究

讨论了雷达高度表脉冲回波受地形，地貌，植被及雷达本身参数（波束，发射功率，频率，天线及指向误差角ζ）影响的问题，给出了一种在飞行实验中运用高速Ａ／Ｄ直接测量雷达高度表回波波形数据，通过对飞行试验数据积累，分析，处理及计算机仿真，获得了高度表测高修正模型的方法。     

雷达高度表回波捕获技术研究

为了对雷达高度表回波信号进行采集以确定回波前沿形状与地貌的关系,建立雷达高度表的测高模型,从而提高其测高精度,需要对回波信号进行准确定位．根据雷达高度表的工作原理及工作条件,特别是回波与杂波共存的条件,给出了一种回波的捕获算法及其实现电路,并进行了性能分析．     

雷达高度表回波捕获技术研究

为了对雷达高度表回波信号进行采集以确定回波前沿形状与地貌的关系，建立雷达高度表的测高模型，从而提高其测高精度，需要对回波信号进行准确定位，根据雷达高度表的工作原理及工作条件，特别是回波与杂波共存的条件，给出了一种回波的捕获算法及其实现电路，并进行了性能分析。     

高度表地面回波能量仿真分析

雷达高度表是一种测量对地相对高度的装置,目前在军用和民用方面都有着很广泛的应用。本文对雷达高度表对地辐照时接收到的地面回波进行研究,首先对经典方程进行推导,然后根据推导过程建立了仿真模型,接下来通过仿真模型对地面回波进行了各方面的研究,特别对天线倾侧时地面回波能量在距离上的分布情况进行了详细地探讨,并与其他仿真模型做对比,最终研究结果可对高度表设计提供理论参考。     

基于天底点的散射回波信号处理算法

针对基于速度选通雷达高度表在森林等纯散射地面无法工作的问题,在深入分析纯散射地面回波信号模型及回波功率分布特征的基础上,提出了基于天底点的散射回波信号处理算法.该算法通过检测天底点附近回波中的多普勒和相位信息,进行相应补偿后获取回波中的二相编码信息,对所得二相编码信号进行相关处理后通过检测其峰值实现高度测量.仿真结果表明,该算法能够有效解决雷达高度表在森林等纯散射地面无法工作问题.     

基于OpenGL建模技术的航海雷达回波图像生成方法

为解决当前航海雷达仿真器中雷达回波图像不真实问题,以岸线为例提出基于OpenGL建模技术的模拟航海雷达回波的新方法,研究雷达回波图像生成技术,给出雷达岸线回波及雷达岸线回波图像的生成算法.对RGB、HIS颜色模型在模拟雷达回波强度上的应用进行探讨,给出目标回波强度的数学模型.通过加入噪声模型,实现航海雷达岸线回波仿真,其结果与电子海图显示基本相符.     

真实地形环境下低空雷达目标回波信号分析

针对低空雷达目标与杂波、环境难于一体化建模的问题,提出了一种分析真实地形环境中低空飞行目标的雷达回波信号的实景相干复合方法(CHIAL).以机载脉冲多普勒(PD)雷达为平台,首先将半空间并矢格林函数引入物理光学方法中,结合图形电磁学计算低空目标的雷达散射场强度,然后利用地形高程数据和地形地物分析数据,得到杂波单元的散射特性,通过相干杂波模型产生地杂波,最后将所有雷达回波送入各自的距离门,并加入噪声信号,模拟包含目标特性和杂波特性的有效回波信号.与传统复合建模方法相比,CHIAL方法的目标回波信号和杂波信号更加准确.对机载PD雷达探测低空目标的仿真实验表明,CHIAL方法在处理90m×90m地形高程数据时,杂波分布和信杂比与理论分析基本一致,有很强的系统工程实用价值.     

基于混合罚函数法的认知雷达波形设计

针对认知雷达发射波形的信杂噪比(SINR: Signal to Interference plus Noise Ratio) 往往需要大于一定阈值的问题, 在传统波形设计准则的基础上建立一种新的认知雷达波形发射系统模型。此模型以目标与回波间的互信息为目标函数, 以信杂噪比和能量作为约束条件, 通过混合罚函数法对模型求解, 最终获得认知雷达的最优波形。仿真实验证明, 该波形可以将波束能量分配给杂波响应较弱、目标响应较强的频段, 满足认知雷达对发射波形的要求, 从而解决了发射波形的SINR 阈值问题, 并最大化目标与回波间的互信息, 具有较强的应用性。     

应用Ansoft软件进行雷达高度表设计仿真

对雷达高度表进行了理论分析,给出了Ansoft Serenade仿真的模块框架,并用Ansoft对发射机进行了仿真,仿真结果表明设计的雷达高度表达到指标要求,运行稳定,可靠。     

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