Papers by Keyword: Capacitance Measurement

Abstract: Each type of coal has different composition and properties, which determine the coal rank. One of the new methods for determining the quality of coal is by measuring its capacitance. It is formerly known that the difference in the moisture content of coal can be determined from the difference in its dielectric properties. The purpose of this paper is to characterize the various types of coal based on capacitance measurement. The samples used are Lignite, Sub-bituminous, Bituminous, and Anthracite. The proximate analysis testing was done to determine the content of moisture, volatile matter, ash, and fixed carbon. Capacitance value is measured using 2-channel data acquisition system (DAS) and parallel plate capacitive sensor at frequency 2.5 MHz. The results shows that the capacitance values of each type of coal are different. The capacitance value is affected by moisture content of coal since the moisture content and capacitance value have a linear correlation. And also, the signal characterization using frequency from 1 kHz to 5 MHz was performed to verify whether the frequency used in the DAS is able to characterize coal types.

Abstract: The capacitance among the structure of the accelerometer is rather small, usually at sub-pF level. Detection of the capacitance among the sensor’s tiny structure and analysis of the variation of these capacitances are necessary to improve the sensor’s performance. In this paper, one capacitance detect circuit for minimal capacitance is designed. Simulation and experiment results indicate a good linearity when the circuit is applied to detect capacitance range from 0.5pF to 5pF.

Abstract: A preliminary study about the development of Electrical Capacitance Volume Tomography (ECVT) for determining moisture, calorie and the flow of coal mass real-time on the conveyor has been done. This study aims to examine the capability and sensitivity of ECVT as a capacitance measurement system to investigate the correlation between moisture in coal and its dielectric property. The ECVT system comprises of a 2-channel rectangular sensor, data acquisition system and a computer system to control the measurement, process data and display the data of normalized capacitance of coal as the result. The linear correlation between moisture in coal and data of coal relative capacitance is obtained and presented in this paper. The results have shown that ECVT has good capability and sensitivity as a system to monitor the dielectric property and behavior of coal which are affected by the moisture content

Abstract: In borate buffer solution, anodic oxide passive film was formed on 316SS at 0.6 VSCE. Chemical composition and semiconductor properties of the film were studied by XPS and capacitance measurement. It’s determined from the results that the film has duplex structure with inner oxide layer and outer hydroxide layer. The inner layer behaves as p-type semiconductor, while the outer layer shows n-type semiconductor. A p-n junction is formed at the interface of outer and inner layer, and it plays an important role in the protective effect on the metal matrix.

Abstract: In order to achieve the real-time monitoring internal state of composite specimen embedded shape memory alloy wires, a new wireless monitoring method in which PS021 is used to measure the capacitance change of composite structure is proposed. The micro-capacitance measuring principle of PS021 and the design of hardware and software of system are introduced in detail. The capacitance signal between some two wires of composite structure embedded SMA is measured by the PS021 module, and the measurement data are processed by C8051F330 micro-controller and wirelessly sent to PC by PTR4000. Compared the tested results with that of the high precision LCR meter, experimental results show that the relative error of system is less than 4.5%.

Abstract: We investigated the influence of an external magnetic field for the carrier injection process of a metal (Au) / insulator (Cr2O3/Fe/CeO2) / semiconductor (Si) (MIS) capacitor, in which the insulator consists of magnetic materials. By applying an electric field, electrons propagating through the CeO2 layer from Si were injected into the Fe or an oxygen deficiency layer formed around the Fe layer. When a magnetic field was applied, the hysteresis window width of this capacitor was reduced. I-V curve analyses under a magnetic field revealed that this reduction was more likely due to the magnetic state of the Fe layer and the interaction between Fe and Cr2O3.

Abstract: The effects of pH value and chloride ions concentration of the solution on pitting susceptibility and semiconducting properties of passive films formed on 18Cr-18Mn-2Mo-0.9N high nitrogen austenitic stainless steel (HNSS) were investigated using potentiodynamic polarization and capacitance measurement methods, respectively. The anodic polarization curves show that HNSS exhibits excellent pitting corrosion resistance in the solution with different pH values and chloride ions concentration, and the pitting corrosion resistance of HNSS decreases a little with decreasing the pH value or increasing the chloride ions concentration of the solution. The passive films formed on HNSS in the solution with pH values ranging from 1 to 9 or chloride ions concentration from 3.5 wt% to 20 wt% NaCl behave as n-type semiconductors. With increasing the pH value or decreasing the chloride ions concentration, the shallow donor and deeper donor densities decrease and the flat bland potential decreases, and the thickness of space charge layer increases. The deeper donor increases and then the second positive slope of straight linear region disappears with decreasing the pH value or increasing the chloride ions concentration of the solution, which can be attributed to the formation of Cr6+ is depressed.

Abstract: We investigated the magnetic and dielectric properties of a metal (Pt)/insulator (Cr2O3)/semiconductor (Si) (MIS) capacitor composed of magneto-electric (ME) materials. The capacitor has anti-ferromagnetic properties and a very small electrically induced magnetic moment. It also shows capacitance-voltage (C-V) properties typical of a Si-MIS capacitor without any hysteresis. By inserting a thin Cr2O3-x layer, the C-V curve has a hysteresis window with a clockwise trace, which indicates that electrons have been injected into the Cr2O3-x layer. These results indicate that this MIS capacitor contains a floating gate and an ME insulating layer in a single system.