工业热电偶检定过程中参考端温度补偿分析

热电偶检定过程中因参考端温度不稳定常常引起测量数据不准确,检定结果无法确定。本文提出用补偿导线法和参考端温度补偿器法消除测量误差,解决了标准热电偶检定装置不能检定工业热电偶的问题。     

二等标准铂铑10-铂热电偶测量结果的不确定度评定

二等标准铂铑10-铂热电偶分度采用同名极比较法，测量误差直接传递到下一级计量器具，即温度计量器具，其测量不确定度是衡量是否满足检定廉金属热电偶的条件。通过对二等标准铂铑10-铂热电偶测量不确定度评定，可比较测量水平。     

二等标准铂铑_(10)-铂热电偶测量结果的不确定度评定

二等标准铂铑_(10)-铂热电偶分度采用同名极比较法,测量误差直接传递到下一级计量器具,即温度计量器具,其测量不确定度是衡量是否满足检定廉金属热电偶的条件。通过对二等标准铂铑_(10)-铂热电偶测量不确定度评定,可比较测量水平。     

铂铑10-铂热电偶计量标准测量不确定度分析

按照规范JJF1059-1999《测量不确定度评定与表示》和检定规程JJG75-1995《标准铂铑10-铂热电偶》的要求,结合实际工作经验,对二等铂铑10-铂热电偶测量结果的不确定度进行了分析。     

标准热电偶检定系统测量不确定度的评定

根据国家计量技术规范JJF1059—1999《测量不确定度评定与表示》的要求,对标准热电偶检定系统测量结果的不确定度进行评定,阐述了该系统测量不确定度的来源、定量方法及最终合成与表示。     

二等标准铂电阻温度计测量不确定度评定

利用热电偶热电阻综合标准装置,对二等标准铂电阻温度计进行检定,所得示值误差的测量不确定度的评定.     

二等标准铂电阻温度计测量不确定度评定

利用热电偶热电阻综合标准装置，对二等标准铂电阻温度计进行检定，所得示值误差的测量不确定度的评定。     

铂电阻温度计工作基准装置在锌凝固点的测量不确定度

依据国家与电力行业标准的要求，主要评定铂电阻温度计工作基准装置在ITS—90温标的定义固定点之一：锌凝固点的测量不确定度。评定的方法和结果可用于在该点使用标准铂电阻温度计建标、检定／校准及高精度测量的不确定度分析。     

热电偶温度测量系统中电磁继电器的影响分析

热电偶是一种价格低、方便使用的温度传感器。在综合性的检测设备中部分对测试精度要求不高的温度测量,通常会选用热电偶作为传感器。热电偶通常与延长线及显示仪表共同组成一组测量系统。为降低成本及柜体安装设计,有时需引入继电器实现分别测量的目的。测量系统中增加电器元件将对测量精度和不确定度产生影响。研究分析了热电偶温度测量的原理以及继电器结构工作的原理。分析在热电偶测量系统中增加电磁继电器,对信号调理电路的设计产生的影响,并通过试验验证不同方案电路设计对测量系统不确定度的影响,给出一套适宜的电路设计方案。试验结果表明:测量系统中无继电器接入和测量系统中接入1个继电器常开触点两种方案,测量不确定度U<1℃。本次研究给后续的热电偶测量系统的设计提供参考意见。     

微机控制的热电偶自动检测装置

微机控制的热电偶自动检测装置,主要用于检测热电偶,它可以控制三个测试炉,设定13个温度点,对八种类型的60支热电偶同时进行自动检测。并且能在检定温度点上、下10℃内对热电偶之热电势作准线化圆整计算,输出打印表格。由于配有IEEE 488接口,可以方便地与各种仪表连接。本装置在用户通过键盘输入被测热电偶类型,检定温度点之后,整个检测过程包括升温、恒温、数据采集、数据处理、打印制表都是自动化的。     

Ferroelectric phase transition and electrical properties of Ba(Bi0.5Ta0.5)O3

A lead free polycrystalline material Ba(Bi_0.5Ta_0.5)O₃ was prepared by a standard high-temperature solid-state technique (calcination temperature?=?1180 °C and sintering temperature?=?1200 °C) using high-purity ingredients. The room temperature X-rays diffraction analysis of the material has confirmed its formation in the monoclinic crystal system. The study of microstructure using scanning electron microscopy (SEM) shows that the compound has well-defined grains uniformly distributed throughout the surface of the sample. Detailed studies of dielectric and impedance properties of the material were carried out in a wide frequency range (1 kHz ?1 MHz) at different temperatures (30 °C to 490 °C). Dielectric study shows that the material has ferroelectric properties with diffuse-phase transition around 315 °C. Complex impedance spectroscopic analysis establishes some correlation between the microstructure and electrical properties of the material. The frequency dependence of ac conductivity follows the Jonscher’s power law. The dc conductivity, calculated from the ac conductivity spectrum, shows the negative temperature coefficient of resistance behavior similar to that of a semiconductor. The temperature dependent pre-exponential factor shows peak, and frequency exponent possesses a minimum at transition temperature.     

Low temperature cofirable MnZn ferrite for power electronic applications

A new MnZn ferrite tape material for sintering at 900 °C and its performance in power electronic embedded multilayer inductors of several μH inductance are described. The low sintering temperature is achieved by optimizing powder processing and sintering additives. The material is suited for processing within the low temperature cofired ceramics (LTCC) technology and it is particularly compatible with low loss Ag metallization. Although reduced by a factor of two compared to high-temperature sintered material, its relative amplitude permeability of 700 allows for numerous device applications below the Curie temperature of 260 °C. Volumetric losses are not affected by the new material formulation since increased hysteresis losses are compensated by reduced eddy current losses. Power line filters with ceramic integrated inductors and surface mounted capacitors exhibit a current capacity of up to 10 A and a shift in cutoff frequency compatible with the measured B–H curve of the material. By integration of these inductors with conventional dielectric LTCC tapes a strain-induced permeability quenching is revealed and attributed to magnetostriction. Therefore good thermal matching between tape materials is needed, but the effect also permits construction of variometers and pressure sensors without moving mechanical parts.     

A study on locational configuration of distributed generators under uncertain demand growth

The distributed generator (DG) has several advantages over the large‐scale power plant and is expected to complement the power system. In this paper, we focus on the locational flexibility and short lead time as advantages of DG, and examine the influence of uncertainty of demand growth on the optimal locational configuration of DGs in the transmission network and on the amount of installed DG. The results indicate that the total capacity of installed DGs is greater under uncertain demand growth than under certain growth. It is also indicated that under uncertainty, the installed DG capacity is distributed generally in proportion to the growth of the local loads. The latter finding suggests that the expected load growth at each point could be a useful indicator for screening candidate locational configurations of DGs. © 2000 Scripta Technica, Elect Eng Jpn, 133(4): 53–62, 2000     

预电离大气压低温等离子体射流及其在表面清洗中的应用

具有高化学活性的大气压放电低温等离子体射流具有潜在的应用价值。为此,介绍了一种利用预电离办法产生Ar/O2等离子体大气压低温射流及其在表面油污清洗中的应用。采用针电极放电等离子体作为预电离源,为射流介质阻挡放电(DBD)提供种子电子,使得射流DBD的击穿与维持电压得以降低,即使在氧气与氩气体积比高达6%时,也可以产生均匀稳定的放电模式。采用光纤温度传感器检测得到放电等离子体气体温度在390～440K,而Boltzmann斜率法计算得到的电子激发温度为4640K,通过示踪元素法计算得到氧原子数密度在1017 cm-3量级。将该射流应用到玻璃表面油污清洗,最大清洗速率可达0.1mm/s。所以预电离技术可以产生具有高化学活性的均匀放电的大气压低温等离子体射流,该射流在表面油污清洗中具有较高效率。     

红外测温技术与变电站图像监控系统的融合研究与实现

首先基于红外测温原理构建了系统测温模型和温度修正模型;然后根据电力系统实际需求,确定了红外测温仪的性能指标,并依据模型对仪器测温结果进行修正,提高了测温精度;最后针对具体的图像监控系统,提出软硬件实现方案,并对原有系统进行了二次开发,实现了通过图像监控画面选择待测电力设备,并控制站端红外测温仪动作。系统实现简单,成本低廉,具有一定的工程应用价值。     

Electrical and structural characterization of PTCR pure BaTiO3 nanopowders synthesized by sol–gel emulsion technique

BaTiO₃ ceramics have been widely studied for its application as multilayer ceramic capacitors. However, they have been reported to deviate from their insulating to semiconducting behavior upon doping, and are used as positive temperature coefficient (PTC) thermistors and transducers. In this work, sol–gel emulsion technique was used for synthesis of BaTiO₃ powders of various shapes and sizes. The synthesized powders were calcined at two different temperatures i.e. 750°C, and 1000°C. XRD revealed the powders to be primarily cubic in structure. Presence of tetragonality was noted in the powders calcined at 1000°C. Crystallite size was calculated for the powders calcined at 750°C and 1000°C. Average particle size of the prepared powders varied from 42 to 94?nm. The shape and size of the particles were dependent on the type and concentration of the surfactant used. The synthesized material showed positive temperature coefficient of resistivity (PTCR) behavior. From the recorded resistivity values a maximum of 10¹⁰ Ωcm was achieved. The ferroelectric to paraelectric transition temperature, Curie point, (T_c) was found to be at 75°C from the impedance spectroscopy analysis for the prepared material.     

Studying the effectiveness of using pneumoimpulsive technology for cleaning the platen surfaces of the PK-38 boiler at the Nazarovo district power station

A new pneumoimpulsive technology, central to which is an impact effect of air jet on ash deposits, was proposed for carrying out continuous preventive cleaning of the platens installed in the steam superheater primary and secondary paths of the PK-38 boiler at the Nazarovo district power station. The pneumoimpulsive cleaning system was mounted in the PK-38 boiler unit no. 6A, and the cleaning system tests were carried out during field operation of the boiler. Owing to the use of the proposed cleaning system, long-term (for no less than 3 months of observations) slag-free operation of the platen surfaces was achieved in the range of steam loads from 215 to 235 t/h with the average load equal to 225 t/h at furnace gas temperatures upstream of the platens equal to 1220–1250°C.     

ONOFIC-based leakage reduction technique for FinFET domino circuits

A new technique ON/OFf logIC (ONOFIC) is proposed in this paper for designing domino logic circuits in fin-field effect transistor (FinFET) deep submicron technology. In this technique, a block named ONOFIC is inserted between pull-up network (PUN) and pull-down network (PDN) of domino circuits. The proposed technique is simulated in FinFET short gate (SG) and low power (LP) mode. The subthreshold current which plays a major role to determinate leakage power is very low in this technique. Two-, 4-, 8-, and 16-input OR gates are simulated with 32-nm node FinFET technology. In FinFET LP mode, the subthreshold leakage power of the proposed technique is reduced by 15% to 24.3% at 25°C and reduced by 8.71% to 23.4% at 110°C compared with standard domino circuits. The subthreshold leakage power of the proposed circuit is reduced by 19.2% to 57.3% at 25°C and reduced by 17.6% to 60.7% at 110°C compared with leakage control transistor (LECTOR)-based circuits. In FinFET SG mode, the subthreshold leakage power of the proposed technique is reduced by 7.69% to 17.7% at 25°C and reduced by 0 to 7.85% at 110°C compared with standard domino circuits. The subthreshold leakage power of the proposed circuit is reduced by 60.4% to 73.9% at 25°C and reduced by 45.1% to 65.5% at 110°C compared with LECTOR-based circuits. The proposed technique is also efficient to reduce subthreshold leakage power in deep nanometer technology nodes from 7 to 20 nm.     

Application of GDC-YDB bilayer and LSM-YDB cathode for intermediate temperature solid oxide fuel cells

Yttria-doped bismuth (YDB) and gadolinia-doped ceria (GDC) are investigated as a bilayer electrolyte for intermediate temperature solid oxide fuel cells (IT-SOFCs). LSM-YDB is used as a cathode material in order to improve the poor ionic conduction of LSM and the compatibility with the YDB electrolyte. The performance of the bilayer cell was measured under humidified H₂ (3 % H₂O) atmosphere and an operating temperature between 500 °C and 650 °C. The polarization resistance and ohmic resistance of the GDC-YDB bilayer cell were 0.189 Ωcm² and 0.227 Ωcm² at 650 °C, respectively. The bilayer cell showed 0.527 Wcm^?2 in the maximum power density at 650 °C, which is about two times higher than the single-layer cell of 0.21 Wcm^?2. The OCV of the bilayer cell was 0.89 V at 650 °C, suggesting that the electronic conduction caused by the reduction of ceria was successfully suppressed by the YDB layer. The introduction of an YDB-GDC bilayer cell with LSM-YDB cathode thus appears to be a promising method for improving the performance of GDC-based SOFCs and reducing operating temperature.     

A high‐order curvature‐corrected CMOS bandgap voltage reference with constant current technique

A high‐order curvature‐corrected complementary metal–oxide–semiconductor (CMOS) bandgap voltage reference (BGR), utilizing the temperature‐dependent resistor and constant current technique, is presented. Considering the process variation, a resistor trimming network is introduced in this work. The circuit is implemented in a standard 0.35‐µm CMOS process. The measurement results have confirmed that the proposed BGR operates with a supply voltage of 1.8 V, consuming 45 μW at room temperature (25 °C), and the temperature coefficient of the output voltage reference is about 5.5 ppm/°C from −40 °C to 125 °C. The measured power supply rejection ratio is −38.8 dB at 1 kHz. The BGR is compatible with low‐voltage and low‐power circuit design when the structure of operational amplifiers and all the devices in the proposed bandgap reference are properly designed. Copyright © 2012 John Wiley & Sons, Ltd.