四象限探测器光斑定位精度影响因素研究

基于四象限探测器的光斑位置检测原理,建立了不同光斑半径、能量分布和探测器死区等影响因素下四象限探测器输出偏置电压与光斑位置的表征关系．数值仿真结果表明：通过选择合适的光斑半径大小、探测器的测量区域、选择死区较小的探测器等,可有效提高探测器的定位精度．基于仿真分析,搭建了测试实验和利用均匀光斑、探测器存在死区情况下的表征方程对测量结果进行数值计算．实验结果表明：与标准值比较,在该表征方法下,在300μm范围内,四象限探测器光斑中心定位精度为0.35μm,均方根为0.18μm.     

m序列法测量室内脉冲响应的非线性失真分析

m序列法测量室内脉冲响应已经被广泛接受，鉴于实际系统中的噪声和非线性会降低脉冲响应测量的精确性，对m序列法测量过程中室内系统微弱非线性所引起的失真进行了分析．叠加有微弱非线性的室内系统在时域可以等效为一个线性子系统和非线性无记忆环节的级联模型．根据该模型，推导了单一非线性作用下运用m序列法测量的室内脉冲响应误差，并且分析了该方法对各阶非线性的抑制能力．仿真实验验证了推论的正确性．     

基于距离和信息的单目标精确跟踪

对仅有“距离和”测量信息的多传感器系统提出了一种对量测方程预处理的快速卡尔曼跟踪算法．该卡尔曼跟踪算法通过对量测方程预处理得到目标位置与“距离和”测量量成线性关系的观测方程；状态变量只选目标的空间坐标，而速度矢量仅作为确定性输入量加入状态方程，速度矢量通过引入速度“伪测量值”滤波得到．并同以前的跟踪算法仿真比较表明，该方法计算量小，收敛速度快，精度高，具有一定的实用价值．     

空基多平台多传感器机动目标自适应跟踪

在空战中，需要基于空中移动平台对机动目标进行自适应跟踪．由于机动目标“当前”统计模型符合实际目标的动力特征，所以文中基于该模型，针对空基多平台多传感器环境，推导了机动目标跟踪的状态方程和测量方程，并给出了机动目标自适应跟踪算法．Monte—Carlo仿真表明，该方法能有效地估计出机动目标的运动状态．     

全自动红外导引头成像光斑测试仪的研制

研制了一种全自动1．064μm红外导引头的成像光斑测试仪,介绍了各部分功能实现的措施以及最小成像光斑和离焦光斑的图像处理方法,该测试仪以1．064μm导引头为被测对象,采用1．064μm的激光光源模拟无穷远点光源,以红外面阵CCD探测器为接收器,实时采集的信号通过RS-232串口通信进入计算机,采用重心法对所采集的光斑信号进行处理,分析光源通过被检测系统后在其焦面上和成像光斑的质量,它用数据和三维图形显示测量结果,可用于检测红外导引头最佳像面和离焦像面光斑的位置、大小及光能分布,并用于测试轴外视场的光斑,全部检测实现了“一键通”,该方法可以广泛应用于不同光学系统的检测,评价光学系统的质量,特别是光学聚焦系统的质量。     

基于卷积模型的核信号仿真

NaI(Tl)探测器因具有探测效率高和成本低等优点,常被用于核辐射能谱测量和核辐射监管等领域．由于实验条件等的限制,研究人员往往较难获取理想的实验核信号,虽然可以借助探测器的仿真信号来实现研究目的,但是常规的探测器单指数或双指数模型和实际采集到的核信号模型存在一定的差异,需要一种更为精准的数学模型对探测器输出信号进行描述．我们通过对探测器信号形成过程分析,将探测器视为线性时不变系统,探测器各个部分响应的总卷积即为输出的核信号模型．本文建立的探测器输出信号卷积模型,结合实测伽玛源的幅度分布规律和相邻脉冲时间间隔分布规律,可以提供更精确的NaI(Tl)探测器输出信号,以便用于伽玛能谱测量算法研究;通过调节脉冲间隔时间大小,可以仿真不同计数下探测器输出信号的堆积情形,以便用于堆积信号还原算法研究．经过与伽玛辐射源的对比测试,该仿真信号与真实探测器输出信号一致,既避免了研究人员接触放射源,提高辐射防护安全性,又为开展数字化核信号处理算法研究及能谱算法研究提供了极大的便利性．     

云层红外表观辐射模型的研究

在前人对云层红外辐射与反射模型研究的基础上，建立了导引头实际接收的表观光谱辐射亮度(包含云层辐射和反射、天空背景与路径等效辐射)模型，适用于导引头远离云层以及处于云层中的情况．通过傅里叶光谱辐射计对几种远离云层的中、低云表观辐射亮度进行了实际测量，并与模型计算数据进行对比．结果表明：在3～5μm和8～12μm波段，模型计算与实际测量结果具有较好的一致性，可以用于导引头的模拟分析．     

现场大尺寸测量量值溯源

为了评价大尺寸测量量值的准确性,需要建立大尺寸测量的量值溯源体系．针对研究的大尺寸配对视觉测量网的溯源难题,以激光跟踪仪作为高精度标准仪器,利用四元数空间配准算法将所有视觉传感器测量值统一到激光跟踪仪坐标系下,对其测量值现场原位溯源,并通过空间性能评价实验对激光跟踪仪溯源．实验表明,激光跟踪仪的不确定度为10μm＋0.8μm／m,配对式视觉测量网的不确定度优于0．2mm．应用本文的方法可现场快速对多数大尺寸测量仪器溯源。研制的配对式视觉测量网络满足多数大尺寸测量任务．     

基于粒子滤波的仅有角测量的被动跟踪

基于粒子滤波,提出了仅有角测量无源被动跟踪的新解决方法．该方法采用“当前”统计模型,使用粒子滤波算法,融合了双站测量数据．在双站测量的被动跟踪试验中,仿真结果证实了该方法能有效跟踪高度机动的目标．     

层析三维数字化测量原理及层析图像边缘 精度分析与标定

采用材料逐层去除与逐层光扫描相结合的方法，能同时测量具有复杂内外轮廓的零件，且内外轮廓具有相同的精度．根据要求，系统的精度可达到5．4　μm，分辨力可达到2．6　μm．系统地阐述了该系统的测量原理和测量的各部分组成．在开发的样机上用标准量块对系统的层析图像精度进行了分析及标定．     

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

正~~