电动势测量误差的Taylor级数推导

电位分析法是电化学分析法的一个重要组成部分,在各行各业的应用日趋广泛,因而对它的测量准确度的要求就显得极为重要。本文用Taylor级数对电动势测量误差进行了推导,得出了更精确的计算公式,同时对原计算式的误差问题进行了讨论,加深了学生对电位分析误差的理解。     

电子皮带秤测量误差的分析及改进

通过对电厂输煤系统皮带秤在使用过程中存在问题的分析,找出影响皮带秤计量准确度的多种原因,根据现场实际工况,提出具体的改进方案,并进行论证,阐明实物校验的方法是皮带秤量值溯源的可靠方法,选配了皮带秤的实物校验装置。方案实施后效果显著,运行良好。     

总线式调功器在浮法玻璃锡槽上的应用

锡槽电加热系统的性能对浮法玻璃的生产及锡槽的使用寿命具有很大的影响,现场总线式调功器的智能化、数字化,从根本上提高了测量与控制的准确度,减少了传送误差,保证了锡槽电加热系统的可靠性。     

Absolute measurement of pneumatically conveyed powder using a single long throat venturi

The principle of using a long throated venturi meter to measure the flow rate of two mixed phases is widely published, yet there is no practicable application for accurate measurement in relatively lean particulate conveying. Coal fired power stations would benefit from such a meter. Pulverised coal is conveyed pneumatically through pipes from the mill to the furnace. Control devices that ensure delivery of coal to each burner is equal require an accurate on-line measurement of the coal flowing through each line. Relative comparison of coal flow rate between similar pipelines is possible on-line, but to date no absolute on-line measure has been achieved, and weigh hopper discharge measurement for total coal flow rate is crude. Using a program developed by Azzopardi et al. [B.J. Azzopardi, S.F.C.F Teixeira, C.I. Pulford, A quasi-one-dimensional model for gas/solids flow in venturis, Powder Technology 102 (1999) 281-288.] for calculation of the pressure drop in a two phase venturi, a venturi was designed with optimised geometry to give a measurable sensitivity to coal flow rate at the relatively lean conditions encountered in a power station. The venturi was inserted into a pneumatic conveying test rig designed to simulate a coal fired power station. The program predicted the pressure drops measured in the test rig venturi with good agreement. The pressure calibration graphs thus obtained provided a possible means of calculating the air and coal flow rates. Air flow rate was accurate to within 2%. Coal flow rate accuracy was within 20%. Error analysis showed this error to be related to experiment. The program accuracy was shown to be within 7%. This accuracy merits a full scale power station trial.     

Modeling of an electrothermal explosion in gasless systems placed into an electroconducting medium

An electrothermal explosion in cylindrical specimens surrounded by an annular layer of an electroconducting material is simulated. The entire system is located in a cylindrical metallic casing, which is electrically insulated from the electroconducting medium. Heat exchange with the ambient medium proceeds in accordance with Newton’s law. An analytical solution of the problem of determining stationary temperature fields under inert heating in the absence of chemical heat sources is obtained. Critical conditions of the electrothermal explosion (power of electric heat release) are determined. Inflammation on the specimen axis occurs in the supercritical regime in a certain range of the power of electric heat release. At greater values of the power of electric heat release, ignition occurs on the specimen surface.     

玻璃池窑电辅助加热的物理模拟研究

玻璃池窑的电辅助加热是全面提高池窑效率的有力举措,同时电辅助加热池窑又可以根据市场销售情况自动调节出料量,因而是国内池窑近期发展的方向。本文针对某一试     

Direct measurement and dynamic mechanical analysis on the coexistence of positive and negative electrocaloric effects in Bi0.5Na0.5TiO3-xBaTiO3 solid solutions

Abnormal electrocaloric effect (ECE) is investigated in (1-x)Bi_0.5Na_0.5TiO₃-xBaTiO₃ solid solutions by calorimetry measurements, manifesting itself by the differences in the heats released and absorbed under the application and withdrawal of electric fields, respectively. The abnormal ECE is explained by the coexistence of positive and negative ECEs close to the ferroelectric-to-antiferroelectric transition temperature, which is demonstrated by the structural and ferroelectric properties determined from dynamic mechanical analyses and thermodynamics calculations on the solid solutions under an applied electric field, respectively. A threshold electric field below which the negative ECE occurs is obtained, in comparisons with that predicted by the thermodynamics Maxwell's relations. The abnormal ECE obtained from direct measurement is compared with that calculated by the indirect measurement, and the discrepancy is discussed.     

Accurate measurement of aerosol electric mobility moments

A procedure for the accurate determination of moments of aerosol electric mobility distributions was developed. The main apparatus required is a carefully constructed Hewitt (differential) electric mobility analyzer. The method does not require vanishingly small aerosol flow rates to obtain accuracy. The procedure may be considered a primary standard measurement technique, since no calibration with particles of known characteristics is required.

One application of the procedure is the determination of the mean and standard deviation of particle size for near-monodisperse aerosols. As an illustration, a Dow LS- 1117-B polystyrene latex aerosol was analyzed. The mean and standard deviation of the particle diameter were found to be 0·80 and 0·018 μm, respectively. The accuracy of the mean dia. determination is estimated to be 2 per cent.     

基于CS5463的便携式电能分析仪设计

针对目前所使用的电能分析仪器体积大、交流供电、价格高等问题,设计一种适合油田野外现场的使用要求,用电池供电的便携式低成本电能分析仪,提出并使用了抽油机的功率法平衡度计算、测量方法。使用电能芯片CS5463和主控芯片STC89C58RD＋组成系统,对交流电流、电压的有效值、瞬时值、有功功率、无功功率、功率因数进行实时分析。采取低功耗设计和能量管理,实现了设计要求,满足了使用现场的需要。     

最小二乘法在泵试验台数据测量曲线拟合中的作用

为了保证高精度的数据测量,泵试验台所有的测量仪表均由相关检定单位进行了检定,并出具了相应的检定证书,但是一部分检定证书里的检定数据是离散的、未经处理的,这直接导致了检定数据无法应用到测控系统中去。针对这一情况,提出了兼顾整个量程精度的最小二乘法拟合直线的方法来处理这些数据,以方便测控系统应用这些检定数据并保证数据测量足够的精度。在泵试验台,还需要测量试验泵的输入功率即泵配电机的输出功率,这通常需要安装扭矩仪一类的设备,但是这类设备的安装调试工作量太大,针对这一情况,提出了最小二乘法拟合抛物线的方法,仅仅通过分析电机的输入功率就可以得到电机的输出功率。     

电能质量检测的研究与仿真

根据相关国家标准中的电能质量的5个指标,从测量精度和软硬件实现难度两方面因素考虑,确定各指标的测量方法。采用快速傅里叶变换（FFT）分析电网谐波,通过跟踪电网频率,实现准同步采样,解决FFT的频谱泄露问题。利用FFT的运算结果,在频域里计算出电压电流的有效值、电压偏差、功率和功率因数、三相不平衡度。闪变的测量采用IEC的测量原理,并对其作了修正,通过双线性变换,实现了闪变测量的数字化。     

回转窑轮带和托轮直径测量仪在水泥厂的应用（一）

为确保回转窑能稳定运行,应定期对其支承回转部件--轮带和托轮进行测量和调整.文中介绍的带磁电编码器摩擦轮的外径测量仪,其测径精度为1.5mm.该仪器已在国内15条回转窑测量中得到了实际应用.     

基于人工神经网络的电力负荷预测算法研究

电力负荷数据管理系统是电力营销技术支持系统的组成部分,对电力系统运行有着重要的辅助作用。采用神经网络预测模型．设计输入变量和确定神经网络结构的方法和算法．可以使得从历史样本知识数据到最终预测模型的建模过程变得简单明了,便于实际应用。预测方法是使用MATLAB建立模型,对24个负荷点预测,采用多输入单输出的神经网络预测每天的整点负荷值。因为电力负荷与环境因素有关,在输入、输出向量设计中输入变量加入天气特征值。根据输入、输出向量对BP网络设计。该算法结构简单,最后进行短期负荷预测仿真,仿真结果表明其有较好的预测精度。该模型具有网络结构较小,训练时间短的优点,并考虑不同小时负荷差异,易于实现,具有较高的预测精度．预测误差在15％以下,一定程度上克服传统算法收敛速度慢,容易陷入局部积小的缺点。     

利用电容层析成像技术快速测量油气两相流空隙率的研究

基于12电极阵列式电容传感器电容测量信息,提出了一种油气两相流空隙率测量的新方法.该方法在实际测量过程中,首先对当前流型进行辨识,然后应用相应的空隙率测量模型计算空隙率.空隙率测量模型本质上是不同流型下对空隙率测量敏感的多个测量电容的最佳组合,该组合采用改进的遗传算法并辅以偏最小二乘获得,而流型辨识的结果则是采用电容层析成像技术结合模糊模式识别技术获得.实验结果表明,提出的空隙率测量新方法是有效的,测量精度满足工业应用的要求.     

Measurement of free-radical concentration in solids by electron paramagnetic resonance comparison technique

A brief theoretical background of free-radical concentration measurement by electron paramagnetic resonance (EPR) comparison technique is presented to clarify the criteria required for the measurement. Simple experimental methods are suggested to improve the accuracy of the measurement by taking into account the effects of rf power saturation and instrument parameters on the spectral records.     

硫酸余热利用的实践与思考

介绍衡化分公司硫酸余热利用从采用水箱的简易采热到利用管式汽化冷却器制取 0 .6 MPa低压蒸汽 ,进而到采用余热发电 ,再发展到利用发电后的乏汽作为热源供给钛白生产 ,提高了硫酸余热利用效率。     

基于DSP的便携式多功能电能测量仪的应用研究

介绍了DSP技术在电力测量中的应用，经A/D采样后的电流，电压送入DSP芯片，并进行相关处理。得到所需的电流和电压的平均值。有功功率及功率因数等电力参数。本系统还可以通过通信模块进行远程测量和数据传输。该方法具有灵活，可升级和高效的特点。     

Behaviour of film-forming polymers in a microwave electric field

The application of a microwave electric field to the formation of polyurethane films supported by a glass substrate has been described previously. The present work concerns the investigation of the separated contributions of a polymer and its solvent during the film formation in microwaves. The measurement technique allows the kinetic formation to be observed by means of a specific infra-red pyrometer which indicates the temperature variation of the film surface when submitted to the electric field inside a waveguide associated to a microwave power generator at 2.45 GHz. Present data show that dielectric relaxation losses of structural elements of the polymers form the dominant heating process in microwave coating.     

Experimental Characterization of Chain-Aggregate Aerosol by Electrooptic Scattering

A technique combining the electric field-induced alignment and the transient light scattering was applied to characterize Fe₂O₃ chain-aggregate aerosols. Particles were exposed to a pulsed square electric field with strengths up to 2.S kV/cm. Rotational diffusion constants of the particles were obtained from the decay rate of the relative change in light scattering intensity due to orientation of particles after the removal of electric field. Using a model for rodlike aerosols, average particle length was obtained from the electrooptic scattering data and was compared with the electron microscope analysis of the aggregates sampled with an aerosol centrifuge. The good agreement of the results obtained from the two independent methods demonstrates the applicability of the technique to the in-situ measurement of the fibrous aerosols.     

纱锭输送系统专用设备可行性解决方案

针对当前炭纤维厂家在纤维纱锭的输送过程中存在的同题,提出了全电动力源纱锭输送系统的可行性解决方案,该系统具有定位准确,运行稳定等特点.