非平衡电桥原理热敏电阻温度计的计算机校准与标定

非平衡电桥原理热敏电阻温度计设计原理的基础上,利用传感器及数据处理软件获得准确的温度-电压数据曲线,并利用最值查找、斜率标定、曲线拟合等数据处理工具对数据进行有效处理与标定。相对于传统数据处理及标定方式,具有更高的准确性。     

基于G-M低温制冷机的低温温度计标定系统

设计和搭建了一套5.2—300K温区的温度计标定系统,以G-M制冷机为冷源,进口已标定温度计为定标源,对Cernox负温度系数温度计、硅二极管温度计、PT100铂电阻温度计等进行了标定,获得了其温度特性曲线并进行对比,分析了标定误差,发现该系统具有较高的标定精度,所标定的温度计在其有效温区内能达到±15mK以内的不确定度,与定标源温度计处于同等量级。     

低温温度计筛选系统设计

为了筛选满足诸如长期稳定、读数精确、抗干扰等条件的温度计,需要对温度计进行冷热循环冲击实验——升降温循环实验。设计了一套利用GM制冷机作为冷源的系统,用来实现这一目的。利用Lab VIEW编程控制一台340控温仪,仪器PID自动控制加热,从而实现样品架温度按指定的速率匀速升降温。升降温循环冲击分别在循环前、第10个循环后和最后15个循环后对温度计进行标定。根据标定数据对标定后的温度计经行漂移分析,最终筛选除了漂移较小的温度计。     

碳电阻温度计经验公式的选用比较

碳电阻温度计是低温温度测量的常用温度计之一。在碳电阻温度计标定过程中 ,经验公式的选用对碳电阻温度计标定曲线的正确性有着重大的影响。文中针对这一问题 ,同时结合对现有几十个碳电阻温度计的标定实验 ,得到了碳电阻温度计经验公式的选用受碳电阻温度计本身的材料和其所处的温区等因素制约的结论。     

基于模型预测控制的低温控温策略设计及实验验证

低温温度计的标定中，控温策略是低温温度计标定效率和精度的重要影响因素。本研究搭建了以液氦为冷源的低温温度计全自动标定系统，通过温控仪和Python/QT编写了上位机控制程序，对标定过程中所遇到的控温性能问题进行研究。提出一种基于模型预测控制和PID结合的控温策略，通过计算机仿真进行参数优化与实验测试的方法，对PID控温和模型预测控制控温进行实验验证。结果表明，采用模型预测控制后，温度超调量仅为PID模式下的45.42%,稳态调节时间缩短为PID下的23.61%。该控制方法能够显著提高低温系统的控温性能。     

一种宽温区实用型铑铁电阻温度计的性能研究

一种新型结构的四引线金属壳线绕铑铁电阻温度计已经研制成功，这种温度计具有尺寸小、使用温区宽的特点，同一批温度计具有较好的互换性。本介绍了这种温度计的结构、Ｒ－Ｔ特性、自然效应、稳定性和互换性，讨论了少数点标定和内插方法。     

低温温度计标定装置的研制

国家大科学工程 HT- 7U托卡马克 (Tokamak)是一个全超导核聚变实验装置。装置主机由1 6个纵场 (TF)超导线圈和 1 2个极向场 (PF)超导线圈组成 ,分别采用 4.2 K和 3 .8K超临界氦迫流冷却。选用新型低温温度计 Cernox测量超导线圈系统的温度。文中介绍低温温度计标定装置的研制和温度计 Cernox的标定结果。     

医用低温温度标定方法

低温冷冻手术是以杀死病变细胞、组织,达到治愈疾病的目的,在-40℃以下的低温特别适合实体肿瘤的治疗,其治疗效果主要取决于冷冻温度和冻结界面范围,所以对温度的监测和控制十分重要。介绍了常用医用低温温度计的特点及分度,并提出了(77K-273K)温区的温度标定方法和标定装置控制逻辑系统。该标定装置可实现低温温度的标定,标定温度误差为0.1K。     

基于机器视觉的高精度测量与装配系统设计

在对某些精密产品实现自动化生产过程中,存在难以对装配该产品所需的多种装配小零件进行高精度自动测量与装配的问题。针对该问题,搭建了基于机器视觉技术的自动化测量与装配系统。基于Halcon图像处理软件平台,对零件图像进行了中值滤波、图像增强等预处理;采用了Canny算法对零件求取像素精度的边缘,并运用椭圆曲线拟合法获取了亚像素精度边缘;建立了两种相机镜头畸变模型,采用径向排列约束(RAC)标定法与张正友标定法对相机进行了标定,并对标定精度进行了对比;实验结果表明：本系统的装配同轴度精度能达到0.05mm,零件尺寸测量标准差低于3.8μm,满足工业需求,可以解决工业实际问题。     

低温温度计标定装置中测量引线传热分析

介绍了低温温度计标定装置中的热沉问题;建立了数学模型;找出了计算与热沉接触电引线长度的方法;并给出了实例计算。为解决低温装置中的热沉问题提供了理论依据。     

A wave traveling over a Hopf instability shapes the cochlear tuning curve

The tuning curve of the cochlea measures how intense an input is required to elicit a given output level as a function of the frequency. It is a fundamental object of auditory theory, for it summarizes how to identify sounds on the basis of the cochlear output. A simple model is presented showing that only two elements are sufficient for establishing the cochlear tuning curve: a broadly tuned traveling wave, moving unidirectionally from high to low frequencies, and a set of mechanosensors poised at the threshold of an oscillatory (Hopf) instability. These two components generate the various frequency-response regimes needed for a cochlear tuning curve with a high slope.     

Stability and the maintenance of balance following a perturbation from quiet stance

We investigate stability and the maintenance of balance with the use of tools from dynamical systems. In particular we investigate the application of such tools to the study of the ground reaction forces resulting from an athlete being perturbed from quiet stance. We develop a nonlinear model consisting of a set of coupled vector fields for the derivative with respect to time of the angles between the resultant ground reaction forces and the vertical in the anteroposterior and mediolateral directions. This model contains a basin of attraction bound by a closed curve which we call the critical curve. It is only inside this curve that perturbations can be corrected, with the orbit spiraling onto an attractor corresponding to quiet stance. We show how the critical curve and also the strength of the attractor found in the basin of attraction can be fit to model the experimental data (time series) for an individual athlete. We also discuss how our model can be used to identify nonsymmetric behavior caused by muscle imbalances and differences in the ranges of motion on either side of the body.     

Increased gain through identification and alleviation of dye self absorption in laser pumped dye lasers

The effect of overlapping absorption and emission spectra is to shift the gain curve of a dye to the red side of its fluorescence curve and reduce its gain. It is shown how simple binary mixtures of “adjacent” dyes can be used to produce a new gain maximum in the regions between the gain maximum of the single dyes.     

基于MTB导热系数的测定智能型数据处理系统的制作

针对物理实验教学中难以验证学生报告结果的准确性问题,应用MTB（Multimedia Tool-Book）开发了导热系数的测定实验的智能型数据处理系统,解决了实验数据个数统计、线性插值、智能查表、绘制散热盘温度与时间的关系曲线并求出散热速率、实验结果的不确定度表示等难题,可以准确而迅速地检验实验结果。     

Wave propagation in an excitable medium with a negatively sloped restitution curve

Recent experimental studies show that the restitution curve of cardiac tissue can have a negative slope. We study how the negative slope of the restitution curve can influence basic processes in excitable media, such as periodic forcing of an excitable cell, circulation of a pulse in a ring, and spiral wave rotation in two dimensions. We show that negatively sloped restitution curve can result in instabilities if the slope of the restitution curve is steeper than -1 and report different manifestations of this instability. (c) 2002 American Institute of Physics.     

基于快速骨架提取的三维目标识别(英文)

针对三维目标识别问题,提出了一种基于快速骨架提取的方法。根据骨架所反映的目标拓扑结构,建立了不同目标局部结构之间的对应关系;而在对应的局部曲线段上,采用基于曲线配准的方法进行匹配;以各个局部匹配的成本之和评估不同目标的相似性.这种方法在目标出现一定程度的视觉变形时仍具有较好的识别效果,同时避免了基于曲线方法的匹配目标的局部,而忽略局部之间相互的空间组织的缺点所造成的误匹配.算例结果表明这种算法对于三维目标有较好的识别效果.     

基于快速骨架提取的三维目标识别

针对三维目标识别问题,提出了一种基于快速骨架提取的方法。根据骨架所反映的目标拓扑结构,建立了不同目标局部结构之间的对应关系;而在对应的局部曲线段上,采用基于曲线配准的方法进行匹配;以各个局部匹配的成本之和评估不同目标的相似性.这种方法在目标出现一定程度的视觉变形时仍具有较好的识别效果,同时避免了基于曲线方法的匹配目标的局部,而忽略局部之间相互的空间组织的缺点所造成的误匹配.算例结果表明这种算法对于三维目标有较好的识别效果.     

The evolution of nonlinear resonant oscillations in closed tubes: Solution of the standard mapping

The concern of this paper is the evolution of small-amplitude resonant oscillations of an inviscid gas in a closed tube. The evolution of the oscillations of the gas generated at and near the fundamental frequency and half the fundamental frequency, where experiment shows that shocks are a feature of the final periodic motion, is examined. The basis for the analysis of this nonlinear initial value, boundary value problem on a semi-infinite strip is the Dissipative Standard Map. Since the purpose is to elucidate how the initial rest state of the gas evolves to the final periodic state, the focus of the analysis is on how a prescribed initial curve is mapped, under the Dissipative Standard Map, onto an invariant curve. The method used is to approximate the Dissipative Standard Map, in the small rate limit, by the partial differential equation appropriate to the resonance in question.     

Generalized Verlinde Formulae for Some Riemann Surface Automorphisms

The generalized Verlinde formulae expressing traces of mapping classes corresponding to automorphisms of certain Riemann surfaces, and the congruence relations on allowed modular representations following from them are presented. The surfaces considered are families of algebraic curves given by suitably chosen equations, the modular curve X(11), and a factor curve of X(8). The examples of modular curves illustrate how the study of arithmetic properties of suitable modular representations can be used to gain information on automorphic properties of Riemann surfaces.     

用于轴对称的两级光学聚光器的非成像二次反射镜

本文给出了一种用于轴对称的两级光学聚光器的非成像二次反射镜(non-imaging secondary, NIS), 的工作原理. 在一般的情况下, NIS是由并不限于常用的二次曲线或复合抛物线的高次曲线围绕一次反射镜的中心轴旋转而形成. 本文讨论了确定这样一种曲线的待定系数的求解方法. 在举例的计算中, 除了运用常用的二次曲线, 还特别运用了光学中至今从未用过的三次方曲线, 用以说明NIS可以由一般的高次曲线给出. 作为一个特例, 我们也讨论了新的光学元件在太阳能聚光方面的应用, 在这些应用中, 本文着重讨论了NIS在太阳光的盘面效应的影响下的聚光效果. 关键词： 非成像光学 二次反射镜 聚光光伏 高次多项式