一种准确量热敏电阻温度特性的方法

热敏电阻具有显著的内热效应,是测量热敏电阻温度特性的一个难点。本文介绍一种考虑内热效应,准确测量热敏电阻温度特性的方法,可作为大学物理的一个研究型的实验课题。     

热敏电阻的电阻温度特性实验的教与学

详细论述了正电阻温度系数和负电阻温度系数热敏电阻器的电阻一温度特性，以及热敏电阻自热效应对实验的影响等问题，弥补了当前有些实验教材的不足．     

热敏电阻温度特性的测定

针对热敏电阻温度特性在实验检测中存在的问题,设计出一种新的检测装置,结合传统的数据处理,改革实验教学方法,从而较准确地检测出典型热敏电阻温度特性参数,对热敏电阻温度特性有了一定的了解．     

PTC热敏电阻器的电阻温度特性及应用

本文从半导体陶瓷PTC热敏电阻器入手，讨论了该热敏材料的电阻温度特性，给出了PTC热敏电阻器的测量结果和应用范围。     

一种用于热敏电阻温度系数测量加热器的制作

本文介绍一种加热装置的制作，该装置可代替热敏电阻温度系数测量实验中的加热油槽或水槽。     

半导体热敏电阻和铜电阻的温度特性研究

利用多种方法测量热敏电阻让学生掌握非平衡电桥的工作原理,了解金属导体的电阻随温度变化的规律和熟悉热敏电阻的电阻值与温度的关系.     

热敏电阻温度特性仿真实验的教学分析

大学物理仿真实验是把实验设备,教学内容,教师指导和学习者的思考、操作有机融合为一体,为物理实验改革提供了有力的途径;学生运用多媒体和计算机模拟技术,进行模拟操作、数据处理和分析思考,理解和掌握实验原理和方法.但同时仿真实验也存在有一定的弊端.通过仿真实验热敏电阻温度特性的典型教学,以及调查和分忻,得出了仿真实验在实验教学中的消极影响,并提出了一些需要注意的问题,为大学物理实验改革提供新思路.     

铜电阻和半导体热敏电阻温度特性测量实验设计与实现

传统手动读数据方法和现代数据采集器传感器结合计算机自动测量方法分别对铜电阻、正温度系数热敏电阻和负温度系数热敏电阻进行数据测量,并且作曲线图.让学生掌握传统和现代测量方法、不同类型仪器使用方法、不同种类热敏电阻随温度变化的规律、非平衡电桥原理以及误差分析.     

一种利用通电线圈测量风速的方法

当冷空气流过一个通电的发热线圈时,线圈的温度会降低,其最终的温度取决于空气流速。对一个钨线圈通以恒定电流,将其置于风场中,用台式万用表测量线圈两端电压而得到其电阻,再利用电阻-温度特性测得线圈温度,以此达到测量风速的目的。本文将详细探究这一物理过程,从实验进行验证,最终得到一种可靠的测量风速的方法。研究表明：该方法具有较高的测量精度和较短的响应时间,对流场干扰小。     

一种直接测量W-J参数的实验方法

本文探索了一种直接测量W-J参数的方法. 实验选用NaCl作为试样, 在快速压缩过程中原位测量样品的温度和压力的变化值. 通过温度修正使测量值在原理上更符合等熵压缩过程的结果, 并采用大幅度增压结合中值定理得出中点压力处温度随压力的变化率, 进而根据R=(P/T) (∂T/∂P)_S关系式求出W-J参数, 整个过程没有引入其他参数. 此外, 作为对比, 我们还从相关的物态方程、经验公式和已知参数出发计算了NaCl的W-J参数及其随压力变化的关系. 结果表明: 实验测得的NaCl的W-J参数随压力增加而增加; 实验结果与计算值符合得很好. 这说明快速增压直接测量物质的W-J参数是一种可行且可靠的方法. 关键词： NaCl W-J参数 快速增压 高压     

The use of thermistor probes to measure energy distribution in ultrasound fields

The use of small thermistors coated with absorbing material for the measurement of ultrasound fields is discussed. Equilibrium temperature rise gives a rough measure of intensity, but is affected by convective cooling due to streaming. The initial rate of temperature rise provides an accurate parameter for use in assessing energy density in all types of ultrasound field. Measurements made in standing wave fields show that the thermistor response is related to the pressure component of the sound wave, and is determined by absorption throughout the coating material.     

An accurate and robust numerical method for micromagnetics simulations

We propose a new robust, accurate, and fast numerical method for solving the Landau–Lifshitz equation which describes the relaxation process of the magnetization distribution in ferromagnetic material. The proposed numerical method is second-order accurate in both space and time. The approach uses the nonlinear multigrid method for handling the nonlinearities at each time step. We perform numerical experiments to show the efficiency and accuracy of the new algorithm on two- and three-dimensional space. The numerical results show excellent agreements with exact analytical solutions, the second-order accuracy in both space and time, and the energy conservation or dissipation property.     

An accurate multislice method for low-energy transmission electron microscopy

The conventional multislice method (CMS), originally proposed by Cowley and Moodie (1957), is an important algorithm for image and electron diffraction calculations in transmission electron microscopy. Nevertheless, this method is based on the so-called high-energy approximation, which neglects the second differential term ?²φ(r)/?z² to greatly simplify the calculation without severe loss of accuracy. In the current study, we show that for low-energy transmission electron microscopy (LE-TEM) (<100 kV), the high-energy approximation error becomes large and the accurate multislice method, proposed by Chen and Van Dyck (1997), can be used as an alternative method to obtain more accurate calculations. The accurate multislice method, called the revised real space method (RRS) in this paper, can be realized by treating the propagation and scattering as an entirety in real space. A detailed comparison of the numerical results of the RRS and CMS at different accelerating voltages, Debye–Waller factors, and beam tilts is performed. Results show that for image and diffraction simulations in LE-TEM, CMS is no longer sufficiently accurate and the RRS procedure can be used as an alternative method with reasonable computing time.     

落球法测液体黏度的改进

对落球法测量液体黏度实验进行改进,充分利用物理天平称量精度较高的特性,采用称量及求比值的方法求出小球在液体中受力的大小.该方法避免了一些计算误差和测量误差,可提高测量精度.     

A simple and accurate method to measure program/erase speed in a memory capacitor structure

With the merits of simple process and short fabrication period, the capacitor structure provides a convenient way to evaluate memory characteristics of charge trap memory devices. However, the slow minority carrier generation in a capacitor often makes an underestimation of the program/erase speed. In this paper, illumination around a memory capacitor is proposed to enhance the generation of minority carriers so that an accurate measurement of the program/erase speed can be achieved. From the dependence of the inversion capacitance on frequency, a time constant is extracted to quantitatively characterize the formation of the inversion layer. Experimental results show that under a high enough illumination, this time constant is greatly reduced and the measured minority carrier related program/erase speed is in agreement with the reported value in a transistor structure.     

An amplitude modulation fluorometric method for phytoplankton classified measure

We describe a fluorometric method for phytoplankton classified measure. The sinusoidal-amplitude-modulation (SAM) technique is used in this method. The fluorescence of samples is excited in blue, green and amber excitation channels and demodulated simultaneously. We demonstrate experimentally that the system offers a detection limit of chlorophyll a down to 0.005 μg/L and a detection time of 1 s. Compared with the existing pulse-amplitude-modulation (PAM) fluorometers, this method has advantages of better detection limit and shorter detection time, which can facilitate the phytoplankton classified measure.