共振吸收谱仪测量系统的研制

讨论了共振吸收谱仪测量系统的设计.由于频率越高,信号越微弱,同时要求的AD的采样速度也越高,因而限制了测量频率和精度的提高.通过高速低相差ADC及大功率低噪音放大器的研制,使测量频率范围达到1×10-3～5×102Hz,变频精度达到0.05%;内耗测量精度达到5×10-6,为固体振动能吸收谱的研究提供了必要工具.     

FAST反射面测量样机中反射镜对摄影测量算法的影响分析

FAST(500 m口径球面射电望远镜)是中国在贵州依托当地特有的卡斯特地貌建造的球面射电望远镜,建成后它将成为全世界最大的射电望远镜。其反射面结构由锁网张拉而成,在其500 m口径的反射面内共有约2 200个锁网节点,节点的准确测量是保证望远镜运行精度的重要因素。反射面测量样机采用的是高精度摄影测量相机与精密转台结合的方式,通过旋转转台上的反射镜对反射面内不同位置的目标点进行对准、测量。在常见的摄影测量算法基础上,研究了反射镜的反射对于摄影测量算法的影响;并给出了理想情况下与存在安装误差的情况下两旋转轴在旋转不同角度时反射镜的反射作用在摄影测量算法中的等效转换矩阵。     

激光烧蚀Al靶产生的等离子体信号的飞行时间测量

利用快速存贮示波器(100MHz)对脉冲激光烧蚀固体Al靶产生的等离子体信号的飞行时间特征进行了测量．在YAG脉冲激光基频输出(脉宽10ns,波长1.06μm,能量108mJ／pulse)、烧蚀斑的直径为200μm、靶面上激光功率密度约为1×10     

基于回归分析的绝对式光栅尺精度提高方法

提出一种使用回归分析提高绝对式光栅尺测量精度的方法.分析了影响绝对式光栅尺测量精度的因素以及提高其测量精度的方法;对JC09型绝对式光栅尺的测量值和真值进行回归分析,得到回归方程;对回归方程进行了显著性分析,并提出了修正方程;通过实验验证了该方法能够有效提高绝对式光栅尺的测量精度.实验结果表明:在绝对式光栅尺800mm测量长度内,测量精度由0~18.25μm提高到-4.21~5.72μm.另外,该方法具有成本低、计算量少以及易于实现的优点.     

固体内耗仪测控系统的改进设计

对传统的固体内耗仪进行了改进.主要通过对测控系统的重新设计,使测量频率范围达到1×10-4～5×102Hz,变频精度达到0.05%;内耗测量精度提高到3×10-5,同时消除了原测量方法所带来的系统误差;实现了主控计算机系统的升级.为扩展内耗的研究范围,以及为固体振动能吸收谱的研究提供了工具.     

基于图像识别的动物纤维细度快速测量算法

以图像识别、图像分析为基础,研究动物纤维平均细度测量算法。采用图像二值化、边缘跟踪算法提取纤维边缘,用边缘突变点提取算法、纤维微段识别算法确定纤维微段,以边缘亚像素定位算法获取纤维边缘的准确位置,计算纤维细度。结果表明:基于该算法的动物纤维细度自动测量系统的测量精度达到±0.135μm,该算法能够准确、快速地测量动物纤维的细度,满足自动测量的要求。     

不同方法测定黄土和古土壤样品粒度的比较

用激光粒度仪和沉降法分别测量了黄土和古土壤的粒度分布,通过对比两种方法测量结果,认为激光法测量的重复性和测量精度较高,小于5μm颗粒含量低于沉降法,平均粒径较沉降法偏粗;造成这种差异的原因主要是不同方法的原理不同和样品中颗粒形状不规则所致.黄土风化成壤过程中形成的次生碳酸盐矿物可能主要存在于小于5μm的颗粒内.     

基于对角线测量的机床空间定位误差热变化分析

为了研究数控机床温度变化对机床空间定位精度的影响,提出了一种通过分步测量机床工作空间4条体对角线以快速获得机床空间定位误差的方法.基于这种方法,在不同的温度条件下测量了6组数控机床的空间定位误差,并以z轴定位误差为例进行了分析.在某一机床温度条件下,对空间定位误差进行了预测和补偿,z轴定位误差最大从15μm降低到5μm以内,精度得到了改善.结果证明,分步体对角线测量是一种研究机床空间定位误差与机床温度变化之间对应关系并加以补偿的有效手段.     

基于光学自由曲面的三维位移测量系统

针对数控机床、多轴位移台等多轴系统位移检测中存在的检测方法复杂、测量费用高等问题,利用光学自由曲面具有极大的设计自由度,可简化系统结构、提高系统性能的特点,设计开发了一种基于光学自由曲面的非接触式三维位移测量系统,用于普通机床、多轴位移台等多轴系统位移精度检测.通过设计光学自由曲面基准件,搭建实验平台,建立测量系统的数学模型,完成了测量系统的标定实验、测量系统精度验证实验和三维位移测量实验.结果表明,该测量系统精度达2.8,μm,可用于多轴系统的位移检测.     

双Wollaston棱镜偏振测量系统棱镜安置误差分析

研究双Wollaston棱镜偏振测量系统分光棱镜安置误差对测量精度的影响. 从安置误差对Stockes参量测量的影响出发,研究棱镜纵向、横向及两棱镜光轴夹角的安置误差引起的测量误差. 结果表明:对于一定的偏振测量精度,纵向、横向允许的安置误差随波长和目标偏振度的变化而变化,两棱镜光轴夹角允许的安置误差则为固定值. 研究结果为双Wollaston棱镜偏振测量系统的设计提供了理论依据.      

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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