Advanced Materials Research Vol. 981

Abstract: This study presents a effective approach for the measurement of electric field in liquid dielectric with small Kerr constant based on the principle of Kerr electro-optic effect. In the paper, the distribution of electric field in transformer oil is measured of different electrode materials below 30KV. According to experiments it can be concluded that the intensity of light corresponds with the electric field between the two parallel-plane electrodes in test cell in a certain range of the voltage applied. The conclusion reveals that the distribution and variation tendency of the electric field between the two electrodes can be drawn by the analysis of the light intensity.

Abstract: At present, the error rate of color detecting device is generally between 1%-5%, and mainly for the solids. To improve the detection accuracy further, and adapt liquid color detection, this research uses a new method to build light paths, and combines the United States TAOS's TCS3200 color sensor and STM32 microcontroller. A new type of liquid color detecting device is designed, system structure and testing process of the device are also given. This device has more than 10-bit A/D conversion accuracy, 0.5% or less error rate, and less than 30% of the price of similar products. It has broad promotion and application prospects, and can be widely used in chemistry, biology, grain and other fields.

Abstract: A methane monitoring system, consisting of methane sensor nodes and controllers with ZigBee networks between them, has been investigated for coal mine safety. The nodes were in comparatively flexible position. While not working, the nodes were put into hibernation so as to low consumption. While working, the sensor KGS-20 detected methane and sent voltage to CC2430 to carry on A/D conversion. After data processing by CC2430, the node would alarm and display and transmit data to its controller. The controller transmitted data to monitoring station by CAN bus. In experiment a sensor node was put in methane with eight different concentrations and the results were shown in LCD. The results show that all errors are all less than 0.05% and its average error is 0.023%. The errors are accordance with the rules for error range in coal mine.

Abstract: The wireless video monitoring system contains the video acquisition device,video transmission device,video storage device and VGA display device.In this paper,we use video acquisition device to collect video siganals in real-time.The analog video signal is transmitted by using wireless technology.The video signal is converted to a digital signal by using the dedicated A/D chip. At the same time ,the YCrCb signals will be converted into RGB signals by the format converting module.Then,the digital RGB signals are converted to analog RGB signals through the D/A,and they are finally displayed on the VGA monitor in real-time.The design mainly uses the wireless transmission technology to transmit analog video signals and uses ADV7181 to decode.The controlling system of FPGA deals with the decoded digital signals which will be transmitted to the D/A and the data finally will display in real time.

Abstract: A very sensitive hydrogel coated long period grating (LPG) humidity sensor is developed and experimentally investigated for high relative humidity monitoring. A thin-film of PINPAM hydrogel is deposited onto the cladding of LPG by using dip-coating technique. The transmission spectrum of the coated LPG is studied at different humidity levels. For humidity levels greater than 95%, the resonant dip depth suffers a sharp linear increase with a span of 10.26 dB and the resonant wavelength suffers a redshift of 8.6nm.The proposed hydrogel coated LPG humidity sensor shows a high sensitivity of 2.86dB/%RH at high relative humidity region.

Abstract: To achieve the accurate and non-contact detection of the electrical equipment leakage current at the millampere level, this paper presents a new single-turn cored clamp-type sensor named the Microcrystalline-alloy Rogowski coil. The creative construction technique of the new sensor remedies the disadvantage of the Rogowski coil with the structure of microcrystalline alloy core. The experimental test of the prototype was carried out to show the superior performance and the excellent practical value in the application of the faint current measurement.

Abstract: In this article, an evanescent field absorption sensor based on special U shaped optical fiber is proposed. This optical fiber has a hollow structure and an inner core in the cave. The methylene blue is absorbed into the optical fiber and the absorbance is tested. Results show that the value of the absorption will reflect the concentration of the concentration of methylene blue in optical fiber.

Abstract: The food conductivity is one of impact factors on pulsed electric field sterilization. Abnormal breakdown of high conductivity liquid is also one of the bottlenecks in pulsed electric field sterilization technology. The conductivity of liquid food should be accurate calculated for searching the mechanism of abnormal breakdown deeply. An accurate measuring method of conductivity of liquid food is proposed based on pulse response method. Conductivity can be calculated by data recorded from oscilloscope with electrical pulse treating on the conductance cell. This method can decrease the impact of stray capacitance and polarization phenomenon on measured results.

Abstract: This paper describes a piezoelectric resonant tuning fork designed for temperature sensor. The sensor is based on a directly detection and analyses of relationship between frequency shift and temperature change. The main working components of quartz tuning fork temperature sensor are quartz tuning fork resonator (QTFR) and driving circuit, according to the piezoelectric effect principle of quartz crystal, researching on correlative incentive mode, selecting cut type and setting electrodes reasonably, and applying finite element method and Matlab to simulate and analyze the vibration mode as well as temperature and frequency characteristic. The experimental result indicates that the sensitivity of this sensor can reach 70ppm/°C in the temperature range from -30 to 100°C, it guarantees that precision is 0.05°C, the resolution is 0.02°C, and the response time is 4S.

Abstract: The short-circuit reactance is an important parameter to characterize the transformer ability to resist the attack of short-circuit current in the design the operation process. In this paper, the on-line measuring method for short-circuit reactance based on electrical parameters' characteristics was presented, and the feasibility to carry out on-line monitoring for the transformer operation condition was also analyzed. Besides, the principle of two on-line measuring methods based on respectively exciting current compensation and elimination technique was researched, and the calculation equations were deduced. The comparison between the on-line results measured from moving mold experiment and those from off-line short-circuit experiment showed that these two methods were accurate and valid.