Applied Mechanics and Materials Vols. 130-134

Abstract: Along with the maturity of power electronic technology continuously, induction heating technology with its many advantages has been widely used and developed rapidly. However, due to the disadvantages of series resonant induction heating power, such as low input power factor, great grid pollution, it will bring many hazards. This article will make induction heating power network-side input power factor approximate unit power factor with using Active power factor correction technique, and it makes the net side current and voltage be same phase standard sine wave , reduces the network pollution; and with using DC chopper circuit to complete the adjustment of DC voltage, it achieves induction heating power changes. At the same time, using Matlab software for modeling and simulation analysis on the main circuit and control circuit, the simulation results comply with the design requirements and verify the feasibility of the system design.

Abstract: The linearity correction scheme for VCO tuning characteristics is the key to determine the performance of FMCW radar system. The paper introduces the basic definition of VCO tuning linearity. The linearity correction scheme for VCO tuning characteristics mainly inclues three basic schemes, they are the reactance compensation, open loop and closed loop linearity correction scheme. Analyzing the basic principle of every correction scheme detailedly, and doing a key analysis of the closed loop digital correction scheme; Discussing their advantages and disadvantages, and introducing the latest research progress of VCO linearity correction schemes in detail.

Abstract: An extrinsic Fabry-Perot (F-P) interferometric (EFPI) sensor by using simple etching and fusing method is proposed and demonstrated. The cavity is formed by wet chemical etching of multi-mode fiber (MMF) end face in hydrofluoric acid solutions, and then it is fused to the end of a single-mode fiber (SMF) to form an extrinsic F-P structure. The strain and temperature of EFPI sensor are studied experimentally. The experimental results show that the interference wavelength becomes 2.648nm longer while the strain increases from 0N to 637N, and the strain sensitivity is about 0.004nm/N, and linearity is 0.999. The interference wavelength becomes 0.032nm shorter while the temperature increases from 20°C to 100°C. This kind of sensor has the many advantages of easy fabrication, good reliability, high-repetition, small size, low cost and mass-production, which offers great prospect for sensing applications.

Abstract: Landslide is one of the most serious natural disasters, forecast and early warnings are important. The SMS backhaul of WSN monitor system is discussed in this paper. After analyzing the transmission system of WSN at present, this paper intend to combine GPRS-Internet, SMS-PP and SMS-CB to pass early warning back to inhabitants, so as to further ensure the reliability and instantaneity. In order to send early warning to every person in landslide zone, several situations are considered. With the real-time monitoring system and extensive early warning backhaul, the damages and losses would be reduced.

Abstract: In this note, it is proved that every -sparse signal vector can be recovered stably from the measurement vector via minimization as soon as the restricted isometry constant of the measurement matrix is smaller than . Note that our results contain the case of noisy data, therefore previous known results in the literature are extent and improved. Also we obtain the results on the stability and instance optimality for some random measurement matrices.

Abstract: Real-time monitoring of oil contamination in hydraulic system is one of the most effective measures of prevention and early diagnosis for system failures. A compact on-line particle counter sensor based on light-blockage principle for monitoring hydraulic oil is presented in the article. A novel method is used in this sensor, which can calculate the particle number concentration without a metering pump. The experimental results show that the particle counter sensor can measure the concentration as well as the approximate size of the hydraulic oil particles with a high precision.

Abstract: The influences of CO₂ on the characteristics of a limiting current oxygen sensor in CO₂- O₂-N₂ atmospheres were investigated. The studies indicated that the I-V curves appeared two-stage current plateau at (0~2) V operation voltage in CO₂-O₂-N₂ atmospheres with CO₂ concentration changed from 2.03% up to 12.18% and oxygen concentration remained at 5%、7.5%、10%, respectively. The first saturated current I_L1 appeared in the voltage range of 0.8～1.4 V while the second saturated current I_L2 appeared in 1.65～1.82 V, respectively. The difference between the two current platforms (I_L2-I_L1) and (-ln(1-X_CO2)) showed a good linear relationship. And the oxygen sensor’s up-response time and down-response time to CO₂ were both within 30s. The concentration of CO₂ can be detected at a high working voltage.

Abstract: In this paper, According to mine gas accident frequent and the shortages of traditional gas monitoring system, puts forward some eigenvalue fabry-perot interference (EFPI) technology, its spectrum domain to study the mechanism of white light interference demodulation . establishing the wavelength fiber methane sensor system, realized the sensing information high resolution, wide measuring range and do not suffer light wave, the spectrum domain influence of disturbance synthesis technology. Experimental results show that have an accurate measurement results, it can be applied in underground bad environment method of measuring gas concentration, the research may realize all fiber optical signal measurement, underground only, no electrical signals, strong anti-jamming capability, suitable for inflammable, explosive and other environmental.

Abstract: A kind of high reliability and high-precision division operation achieved by 8051 series SCM was discussed; the algorithm eliminated the limitations of system’s unsigned division through the iterative multiplication. Combined with the application of the TMP36 temperature sensor, the experiment demonstrates that the result is accurate, the algorithm has the advantages of simple algorithm, strong adaptability and high reliability, etc, it is very practical.

Abstract: A readout circuit with high sensitivity and high linearity is proposed in this paper. The applied pressure is sensed by Wheatstone bridge which can reduce the adverse effect of temperature. As the applied pressure changes from 15kPa to 115kPa, the sensitivity of the bridge is 0.36mV/kPa. The current source of the circuit can provide a current with a positive coefficient which can compensate for the inherent high-temperature loss of sensitivity of the Piezoresistive Bridge. Three high-precision operational amplifiers with symmetrical input and rail-to-rail output are used to process the output signal of the bridge. It can provide high CMRR with 123.8dB, open loop gain is 110dB and the output swings from 36.41mV to 4.953mV as the power supply is 5V. A thin film resistors network can compensate for the zero pressure offset and sensitivity by trimming. The high sensitivity of the bridge and the high linearity of the proposed circuit make the readout circuit suitable for monolithically integrated pressure sensor.