Applied Mechanics and Materials Vols. 433-435

Abstract: The flat transducer is composed of 1-3-2 piezoelectric composite and copper shell. The structure of transducer was determined according to design requirement and finite element analysis by ANSYS. The transducer was prepared by using a 25mm×25mm×4.8mm 1-3-2 composite chip, rigid foam backing, copper shell, polyurethane layer and acoaxial cable. The voltage response, source level, receiving voltage sensitivity and other performance were measured. The resonant frequency of transducer is 294kHz, the maximum transmitting voltage response is 159.6dB, 3dB bandwidth is 32kHz, source level is 208dB, receiving voltage sensitivity of the transducer is -203 ± 3dB in the frequency range of 50-250kHz frequency, the beam width of -3dB is 11º in the directivity.

Abstract: The paper introduces a method of digital K-type thermocouple temperature transmitter design, which uses MAX6675, a digital K-type thermocouple converter, MCU and TTL/485 conversion circuit. MCU calculates thermoelectric potential of thermocouple by the result of MAX6675 firstly, and then obtains the temperature by reference tables of K-type thermocouple and linear interpolation method, and result is serial output in digital mode. The method can eliminate interference of analog signal transmission, and improve measurement accuracy.

Abstract: A calibration method of a contact sensor for displacement with a piezo nanopositioning stage is presented in this paper. The experiment system is set up, and an old contact sensor for displacement is calibrated by a P-622.ZCD precision vertical nanopositioning stage, which is tested for a good using status in the end. The calibrating results indicate the error regularity existed in the output values, and there is the stagnation phenomenon during the descending process of the stage after elevation.

Abstract: In order to adapt to the harsh conditions of the coal mine, according to the MA Verified standards, we developed a set of vibration acceleration sensor signal conditioning circuit of mining, used for picking up vibration signal in the coal mine. The conditioning circuit solve the vibration signal of large equipment acquisition problems in coal mine, and lay a good foundation for the research of coal mine equipment vibration signal.

Abstract: In order to solve the decision information fusion issues of resource-constrained wireless sensor network, several decision information fusion rules under exponential distribution fading channel are investigated in this paper. At first, optimal likelihood ratio rule is given. The detection performance of this fusion rule is best, however, this rule acquires channel information which is too costly for resource constrained sensor networks. To solve this problem, suboptimal likelihood ratio fusion rule is proposed which requires only the knowledge of channel statistics. In addition, the reduced forms of the suboptimal are also derived, in the case of extreme channel signal-to-noise ratio (SNR). Theoretical analysis and simulations show that suboptimal fusion rule needs much less computation and information, yet exhibits only slight performance degradation. Suboptimal fusion rules are practicable for resource constrained wireless sensor networks decision information fusion system working in ocean environment.

Abstract: The vibration measurement is one of the new application in the optical sensor. This paper studies a new non-contact optical vibration sensor, and implements the Optical fiber vibration sensor based on FPGA. The totally available measurement range arrived over 300um, and the accuracy of 0.1 um can be obtained . This fiber optic vibration sensor has a low cost, good reliability, and high accuracy measurements.

Abstract: A new kind of solution concentration sensor is designed based on the SMF-EMMF-FBG structure. Sensing characteristics of FBG to solution concentration is researched, sensing detection of four kinds of solution is experimentally realized with the wavelength differences between high modes and the fundamental mode, the higher order modes of the etched multimode fiber is more sensitive to the surrounding refractive index than the fundamental mode.

Abstract: Micro-electro-mechanical systems (MEMS) have played an important role in sensor applications. When applied it in new fields, should answer the following questions: how to use it, how to investigate its work performance, why should use it and so on. To do simulation, the MEMS accelerometer Simulink model of ADXL series, the simple virtual reality model made by vrbuild2, and Sugar3.1 for windows are studied and integrated in the paper. Though compare with vibration test signal, the simulation results show this integrated method have advantage of straightforward, simple, effective.

Abstract: This article presents a kind of high sensitive magnetic transducer which is based on the phase characteristics of giant magnet-impedance (GMI) effect. Then the development process of this new kind of magnetic transducer is discussed with the ideal condition of the GMI sensor elements (the frequency and the amplitude of the excitation current). Compared with the amplitude characteristics of GMI effect, the transducer can make a 10 to 100 times lower frequency. At the ideal condition, the sensor has a sensitivity of 1.6°/Oe, and we can conclude that the sensor has a potential to detect the weak magnetic.

Abstract: In order to improve the reliability and accuracy of inertial navigation system in some navigation applications, the redundant inertial measurement unit (RIMU) is used. In this study, an optimal sensor fusion is introduced, and drift compensation based on this sensor fusion is presented subsequently. And the sensor fusion and drift compensation are combined into one algorithm. In this algorithm, faulty drift sensors are not isolated, but are compensated. So the redundant inertial navigation system can maintain systems redundancy. An errors model of RIMU was derived firstly, the optimal sensor fusion and the drift compensation algorithm were introduced secondly, and several simulations were carried out and proved effective of the proposed algorithm lastly.