常用热电偶温度与电势互换公式

本文将常用的热电偶分度表,依照实际使用的需要,线性回归出电势(E)→温度(T)的多项式,并将镍铬-考铜热电偶补上温度(T)→电势(E)的多项式回归公式,供从事计算机测温控温的同行们使用中参考。该回归公式一律采用单精度计算,是便于在各种类型的计算机(包括单板机、单片机)上都可以使用。回归公式拟合精度高,既适合一般温度测控场合,也适用于要求严格的检定部门。回归的热电偶种类为:铂铑_(10)-铂(S)、铂铑_(30)-铂铑_6(B)、镍铬-镍硅(铝)(K)、镍铬-考铜(EA-2)。     

铂铑—铂热电偶测温中的几个问题

引言铂铑——铂热电偶广泛应用于各种高温炉及其他加热设备以检测或控制温度,属贵金属材料;正确使用铂铑—铂热电偶,不但给国家节约材料和资金,并可得到准确的温度计量。一、热电偶使用时应注意的问题和误差铂铑—铂热电偶产生误差的主要原因之一是寄生电势,贵金属热电偶材料的直径都比较小(φ0.3～φ0.5㎜),在使用中如不小心,容易受到弯曲、挤压、碰伤等而产生机械     

一种提高热电阻测温准确性方法研究

分析了工业铂、铜热电阻电阻-温度特性,以工业铂电阻温度传感器为例,给出了一种提高热电阻测温准确度的方法。通过对工业铂电阻进行多点测试,利用最小二乘法对测得数据进行拟合,得出新的电阻-温度转换公式和分度表。通过试验数据的比较表明,使用该方法可以提高传感器的测温准确性。     

刀具——工件热电偶补偿电路的误差问题

在用刀具——工件热电偶测量切削温度时,常采用铜——康铜补偿电路补偿刀片尾部的附加热电势。因此,研究补偿电路的误差问题是很必要的。Trigger 等人曾根据部分试验指出:在采用铜——康铜组成的补偿电路时,最大不平衡电压输出约为±0.02mv,对于切削钢料来说,测温误差为±2°F。本文通过理论分析和试验研究,证明上述结论是有局限性的。对这种补偿电路,若使用不当,在切削高温合金时不平衡电压有时可达0.34mv,温度误差有时可达(24～30)℃。本文分析了刀片尾部实际温度,补偿电阻及导线内阻对不平衡电压的影响,得出不平衡电压的计算公式,并提出了另一对误差较小的导线,可供选用。     

温度补偿振荡器用SC切谐振器

本文介绍对SC切TCXO谐振器的频温一切角特性的测定情况。θ值是在下转折点温度范围+100℃至-70℃的数值。根据这种谐振器的频率温度(f-T)特性,测出了在不同温度范围(即-40℃—+75℃, -54℃—+85℃和0℃—+60℃)的最佳切角、最小频率偏移和最大频率-温度斜率。业已发现,用普通切割设备就能很容易达到切角公差。初步的滞后测量结果表明,SC切谐振器可以使TCXO的稳定度得到明显提高。     

带热电式二位PID调节的热电偶检定炉

在检定热电偶时,《检定规程》(JJG—73)中规定,当采用双极法检定热电偶时,要求读数一周炉温变化不超过1℃。如果一炉检定五支热电偶,读数一周的顺序如下:标准→被检1→被检2→被检3→被检4→被检5→被检5→被检4→被检3→被检2→被检1→标准。目前大多数工厂的热电偶检定炉仍然是采用手调动作使炉温“恒定”,在检定点温度附近进行测量的。如图1所示:     

硅晶体管精密温度计的线路设计

一概述晶体管的P—N结对温度十分敏感。理论分析和实际测量都表明,温度每增加1℃,晶体三极管V_(be)的绝对值约降低2.2mv。晶体管温度计就是根据这一基本原理设计的。但晶体管的V_(be)与温度T的变化是非线性的,直接用来测温误差大。要用晶体管作感温元件制造精密温度计,必须设法解决V_(be)与T的线性化问题。三极管的V_(be)不仅与温度T有关,而且     

热电偶检定规程宣贯材料(连载之三)—规程的讲解

一、标准铂铑_(10)—铂热电偶检定规程(JJG—75—82)1.概况标准铂铑_(10)—铂热电偶检定规程(以下简称新规程)经国家计量局1982年5月27日批准,并自1983年6月1日“起施行,代替规(G)热—5—65。     

高超声速飞行器热流密度/分层温度/碳化层研究

受试验设备能力限制,地面风洞无法完全模拟高超声速飞行器临近空间热环境。文章采用在飞行器表面开孔安装长时耐高温热流传感器直接测量热流密度的方法,国内首次获得Ma12以上高超声速飞行器表面热流密度时变数据和边界层转捩特征。实测热流值与理论预示值规律相同,两者偏差小于20%。针对树脂基材料导热微分方程中虽考虑了热解吸热项,但未考虑导热系数随温度变化情况,采用在树脂基材料导热微分方程中加入物性参数随温度变化项的方法,计算了飞行器热防护结构内部分层温度和碳化层厚度,并与实测结果进行了比较,不考虑树脂热解特性和材料物性参数随温度变化,理论值高于实测值,最大偏差275~320℃;考虑热解特性和物性参数随温度变化情况,计算值与实测值最大偏差小于70℃。     

全国角度计量测试技术基础知识讲习班考题参考答案

一、圆分度检测的甚本理论与方法1.(l)对应于36“的弧度为:二/180减36。念0 .628 3rad. 2.0.000 096 963rad对应的六十进制角度为:180a/:x 0.000 096 963、0,005 555 57飞20” 2.刻线误差<中>是指圆分度器件刻线的实际位t对于应有位t的偏差,在整周内闭合,即在整周内,所有刻线误差的总和为零.刻线误差往往含有圆分度器件安装偏心所形成的角度偏差.互成180。的两刻线组成“直径”,直径两端刻线误差的算术平均值称为“直径误差”(中),在半周内闭合.故刻线误差<中>与直径误差(甲)的关系为 (叫=1/2{<价>十<中+180“、、} 采用直径误差评定刻划精…     

Stochastic particle acceleration by the forced interaction of relativistic current sheets

We address the problem of interacting relativistic current sheets in self-consistent kinetic plasma simulations within the framework of the Particle-In-Cell model. The interaction is enforced in head-on collisions of up to 10 current sheets at relativistic bulk speeds. The simulations are motivated by the general problem of Poynting flux dissipation in ‘striped wind’ configurations presumably governing the relativistic outflows pervasive in pulsar winds and gamma-ray bursts. We identify the generation of non-thermal particles and formation of a stable power-law shape in the particle energy distributions f(γ) dγ ∝ γ^−s dγ. In 1D, a spectral index s ∼ 2 is observed and attributed to a stochastic Fermi-type acceleration mechanism. In 2D, the generic index of s ∼ 3–4 is retained as in previous simulations of individual current sheets. Whereas in 2D the high energy cut-off is constrained by the limited dissipation of magnetic energy, in 1D the process converts the bulk motion of current sheets towards directed particle momentum of an exclusive class of non-thermal particles.     

Scaling analysis and model estimation of solar corona index

A monthly average solar green coronal index time series for the period from January 1939 to December 2008 collected from NOAA (The National Oceanic and Atmospheric Administration) has been analysed in this paper in perspective of scaling analysis and modelling. Smoothed and de-noising have been done using suitable mother wavelet as a pre-requisite. The Finite Variance Scaling Method (FVSM), Higuchi method, rescaled range (R/S) and a generalized method have been applied to calculate the scaling exponents and fractal dimensions of the time series. Autocorrelation function (ACF) is used to find autoregressive (AR) process and Partial autocorrelation function (PACF) has been used to get the order of AR model. Finally a best fit model has been proposed using Yule-Walker Method with supporting results of goodness of fit and wavelet spectrum. The results reveal an anti-persistent, Short Range Dependent (SRD), self-similar property with signatures of non-causality, non-stationarity and nonlinearity in the data series. The model shows the best fit to the data under observation.     

Learning in an immersive digital theater

The Houston Museum of Natural Science, in collaboration with Rice University has an outreach program taking portable digital theaters to schools and community sites for over five years and has conducted research on student learning in this immersive environment. By using an external independent evaluator, the effectiveness of NASA-funded Education and Public Outreach (EPO) projects can be assessed. This paper documents interactive techniques and learning strategies in full-dome digital theaters. The presentation is divided into Evaluation Strategies and Results and Interactivity Strategies and Results. All learners from grades 3–12 showed statistically significant short-term increase in knowledge of basic Earth science concepts after a single 22-min show. Improvements were more significant on items that were taught using more than one modality of instruction: hearing, seeing, discussion, and immersion. Thus immersive theater can be an effective as well as engaging teaching method for Earth and Space science concepts, particularly those that are intrinsically three-dimensional and thus most effectively taught in an immersive environment. The portable system allows taking the educational experience to rural and tribal sites where the underserved students could not afford the time or expense to travel to museums.     

Development of a gas chromatography compatible Sample Processing System (SPS) for the in-situ analysis of refractory organic matter in martian soil: preliminary results

In the frame of the 2009 Mars Science Laboratory (MSL) mission a new sample preparation system (SPS) compatible with gas chromatography–mass spectrometry (GC–MS) has been developed for the in situ analysis of complex organic molecules in the Martian soil. The goal is to detect, if they exist, some of the key compounds that play an important role in life on Earth including carboxylic acids, amino acids and nucleobases.     

基于LuGre模型的电液加载系统摩擦补偿

为了提高电液加载系统控制精度,针对摩擦问题提出了基于LuGre摩擦模型的前馈补偿方法.建立了用于摩擦仿真分析和补偿器设计的电液加载系统数学模型;通过实验获取并分析了相关的摩擦数据;基于实验数据进行LuGre模型参数辨识,把LuGre模型和辨识结果引入电液加载系统数学模型,并进行仿真结果与实际摩擦数据的对照,证明了LuGre摩擦模型的准确性.设计前馈补偿器,进行了实验对比,实验结果表明前馈补偿器可将摩擦产生的控制误差有效地降至未补偿时的30%左右.      

CoRoT and Kepler results: Solar-like oscillators

The space-borne observatories CoRoT (Convection Rotation and planetary Transits) and Kepler have provided photometric time series data of unprecedented precision for large numbers of stars. These data have revolutionized the fields of transiting exoplanets and asteroseismology. In this review some important asteroseismic results obtained using data from the CoRoT and Kepler space missions concerning stars that show solar-like oscillations are discussed. These results comprise, among others, measurements of the location of the base of the convection zone and helium second-ionization zone in main-sequence stars, the presence (or not) of core-helium burning in red-giant stars, as well as differential rotation in these stars.     

Radioactivity of the Moon and planets

In this report the main results of the study of radioactivity of the solar sistem bodies are considered. The radioactivity of the Moon and planets was measured by means of vehicles in situ. The radioactivity of the lunar samples, brought to the Earth was studied with laboratory equipment.     

Return to Europa: Overview of the Jupiter Europa orbiter mission

Missions to explore Europa have been imagined ever since the Voyager mission first suggested that Europa was geologically very young. Subsequently, the Galileo spacecraft supplied fascinating new insights into this satellite of Jupiter. Now, an international team is proposing a return to the Jupiter system and Europa with the Europa Jupiter System Mission (EJSM). Currently, NASA and ESA are designing two orbiters that would explore the Jovian system and then each would settle into orbit around one of Jupiter’s icy satellites, Europa and Ganymede. In addition, the Japanese Aerospace eXploration Agency (JAXA) is considering a Jupiter magnetospheric orbiter and the Russian Space Agency is investigating a Europa lander.     

基于最小值原理的冗余度机器人动力学控制

为了解冗余度机器人全局法优化中数值求解的困难,本文讨论了动力学方程的建立,无约束和有约束最优控制问题之间的内在联系,重点分析了求解最优控制问题的数值方法,文中提出了双向异步积分迭代的求解正则方程组的直接迭代法,较好解决了状态方程和协态方程稳定相逆给求解两点这值问题带来的困难。     

基于GPS载波相位的微卫星姿态算法研究

GPS姿态系统是利用GPS载波相位测量来确定载体的航向和姿态角。本文对微卫星的GPS姿态系统进行了研究。重点解决短基线的GPS状态算法，讨论了姿态价格函数的了小化方法。测试结果表明，所提的算法对小于1m的基线是有效的。