A self-balancing circuit to measure capacitance and lossconductance for industrial transducer applications

This paper describes a capacitance and loss conductance measuring circuit for the use in industrial transducers. The circuit is based on self-balancing principle and it is immune to stray capacitance. The balancing process is controlled by a micro-controller. The capacitance and loss conductance are represented by the digital feedback signals or by the combination of the feedback signals with the forward path signals. Experimental results show that the circuit has high resolution (0:04 fF) and good linearity (0.999)     

磁流变液电容特性研究

磁流变液的电学特性可以广泛应用于自动控制、医疗、汽车工业、飞机制造等诸多领域。推导出了磁流变电容与介电常数之间的计算公式,制作了可以盛载磁流变液的可变电容,测量了磁流变液作为电解质时电容随磁场的变化情况,以及不同浓度的磁流变液的介电常数随磁场的变化情况,得到了磁流变液电容-磁场变化的曲线和磁流变液介电常数-磁场变化的曲线,最后对实验结果作了分析,得出当磁场增大时,介电常数也变大,从而导致磁流变电容增大的结论。     

The calibration of CERL-Planer capacitance strain gauges

CEGB-Planer capacitance strain gauges are used extensively for monitoring the deformation of components operating in the creep range. However, there are significant differences between the way the gauges are installed for use and the way they are installed for calibration. This paper describes the various types of calibrations that have been carried out to identify the errors associated with these differences and the results show that, providing the manufacturers' recommendations are adhered to, the errors are acceptably small.     

Calculation of multivalued potentials in exterior regions

In magnetostatic and magnetodynamic problems, Ampere's law leads to a multivalued scalar magnetic potential. A method is proposed to calculate this potential through a finite elements program or, in a more efficient way, through a program using a boundary integral method in nonconducting exterior regions. In this case, one has only to define "cutting lines" on the boundary instead of cutting surfaces. Reported here are the results obtained with the three-dimensional eddy-current code Trifou, using the finite element method inside the conductors coupled with an integral method outside, in which the method has been incorporated, for a test model where some global values can be obtained by hand and compared with those obtained by the code. A study of the influence of mesh refinement and of the position of cutting lines is given. Good agreement and numerical stability indicate that the method is operational.     

电容传感器新型电容测量电路设计

提出了一种基于V／T变换的用于电容传感器的电容测量电路。它将被测微小电容变化量转换成时间信号并由单片机进行处理，电路结构简单，电路中没有影响测量稳定性和产生零点漂移的元器件，大幅度地降低了测量过程中的噪声。     

SE同轴测试装置中阶梯电容的研究与优化

在屏蔽材料的屏蔽效能(shielding effectiveness,SE)测试装置中,通过对锥形连接器内导体进行微小移位,优化固定同轴装置的支撑介质的内、外径比值,并在支撑介质中挖去一定厚度的环形沟道构成小电感等技术对阶梯电容进行补偿,减小由截面不连续引起的回波损耗,设计了频率范围为10 MHz至3 GHz的SE同轴测试装置.利用软件仿真验证了表面电阻为5Ω的屏蔽材料在该装置中测试有稳定的SE值,证明该装置不仅改善了基于ASTM D4935测试装置频率范围窄的不足,同时具备良好的阻抗匹配特性.     

Two capacitance dilatometers

Two different dilatometric devices designed for magneto-strictive strain measurements at low temperatures are described. Their sensitivity is of the order of 10^?10 for relative length changes. They are provided with an adjustable gap system which makes it possible to change the gap between the capacitor plates at helium temperature.     

Design of multivalued dc and ac voltage standards

Conclusions A task for the immediate future is to create standard voltage-reference sources and methods and equipment for certifying them, for which the following are required: a detailed analysis of reference-voltage design methods, development of methods of error determination for dc to ac conversion, and scientifically based criteria for selecting and testing all components of reference-voltage sources.It is necessary to devise standards for single-valued and multivalued voltage sources of dc and ac types (with general technical specifications and test methods).Translated from Izmeritel'naya Tekhnika, No. 1, pp. 66–68, January, 1975.     

The inter-electrode capacitance of wedge and strip position sensing elements

A method of calculating the inter-electrode capacitances of wedge and strip position sensing elements is presented. Estimates made using the method are compared to measured values and found to be in resonable agreement. Ank alternative formula is shown to be semiempirical, requiring calibration with similar, already manufactured, wedge and strips before it can be used.     

氧化石墨结构对电容性能的影响

研究了层状结构氧化石墨的片状尺度、结晶态及不同表面官能团含量对其电化学电容性能的影响.以光谱纯和化学纯石墨为原料,采用改进的Hummer法制备氧化石墨(GO),并将部分氧化石墨球磨.用FT-IR和XPS,对氧化石墨表面官能团进行了分析;XRD、FE-SEM和氮气吸附等温线,对氧化石墨结构和形貌进行了分析.利用恒电流充放...     

Oscillation of capacitance inside nanopores

Porous carbons of high surface area are promising as cost-effective electrode materials for supercapacitors. Although great attention has been given to the anomalous increase of the capacitance as the pore size approaches the ionic dimensions, there remains a lack of full comprehension of the size dependence of the capacitance in nanopores. Here we predict from a classical density functional theory that the capacitance of an ionic-liquid electrolyte inside a nanopore oscillates with a decaying envelope as the pore size increases. The oscillatory behavior can be attributed to the interference of the overlapping electric double layers (EDLs); namely, the maxima in capacitance appear when superposition of the two EDLs is most constructive. The theoretical prediction agrees well with the experiment when the pore size is less than twice the ionic diameter. Confirmation of the entire oscillatory spectrum invites future experiments with a precise control of the pore size from micro- to mesoscales.     

The use of capacitance in the measurement of angular and lineardisplacement

This paper describes the use of capacitor bridges in instrumentation for the measurement of relatively large angular and linear displacements. The particular feature of interest lies in the use of printed circuit board technology which allows repeatability at low cost associated with a rugged overall structure. Two possible electronic configurations are described, one being direct and the other using feedback in which the output depends only on the ratio of the capacitances. Experimental results are given for examples of angular and linear devices. They show that this approach readily yields devices with an accuracy of ±1% and indicates that results considerably better than this are ultimately possible     

不同杂化离子对电聚合聚苯胺电容行为的影响

用原位电聚合的方法在不锈钢电极(SS)上制备出了由ClO-4,SO2-4,NO-3,BF-4,TsO-(对甲苯磺酸根)等离子杂化的聚苯胺(PANI)(厚度5～10μm).扫描电镜表明不同的杂化离子对聚苯胺的表面形貌产生了很大影响,分别产生了纳米多孔、颗粒、纤维等多种表面结构.循环伏安研究表明,由硫酸根和高氯酸根离子杂化...     

The step complexity measure for emergency operating procedures: measure verification

In complex systems, such as nuclear power plants (NPPs) or airplane control systems, human errors play a major role in many accidents. Therefore, to prevent an occurrence of accidents or to ensure system safety, extensive effort has been made to identify significant factors that can cause human errors. According to related studies, written manuals or operating procedures are revealed as one of the most important factors, and the understandability is pointed out as one of the major reasons for procedure-related human errors.Many qualitative checklists are suggested to evaluate emergency operating procedures (EOPs) of NPPs. However, since qualitative evaluations using checklists have some drawbacks, a quantitative measure that can quantify the complexity of EOPs is very necessary to compensate for them.In order to quantify the complexity of steps included in EOPs, Park et al. suggested the step complexity (SC) measure. In addition, to ascertain the appropriateness of the SC measure, averaged step performance time data obtained from emergency training records for the loss of coolant accident and the excess steam dump event were compared with estimated SC scores. Although averaged step performance time data show good correlation with estimated SC scores, conclusions for some important issues that have to be clarified to ensure the appropriateness of the SC measure were not properly drawn because of lack of backup data.In this paper, to clarify remaining issues, additional activities to verify the appropriateness of the SC measure are performed using averaged step performance time data obtained from emergency training records. The total number of available records is 36, and training scenarios are the steam generator tube rupture and the loss of all feedwater. The number of scenarios is 18 each. From these emergency training records, averaged step performance time data for 30 steps are retrieved.As the results, the SC measure shows statistically meaningful correlation with averaged step performance time data. In addition, since it is observed that the SC measure seems to have the procedure independent property (i.e. steps that have similar SC scores, whether they are included in different procedures or not, would have similar step performance time), it can be concluded that the SC measure can represent the complexity of steps included in EOPs.