Applied Mechanics and Materials Vols. 220-223

Abstract: In this paper，a survey of UAV (unmanned aerial vehicle ) sensor fault diagnosis technology is presented .UAV sensor fault modes and feature are analyzed. The current research progress and significant approaches in the field are introduced at home and abroad. Finally, the difficulties to be solved and future development trends in the research field are summarized.

Abstract: In this paper, an evaluation method of sensor placement is proposed for an optimal design of health condition monitoring systems. An evaluation procedure is presented which includes failure mode and effect analysis, testability analysis, choice of evaluation indexes, and implementing evaluation. A hidden semi-Markov model is employed to evaluation the effectiveness of sensor measurement. The proposed method is applied to a case of gear box vibration monitoring, where the model is validated using the experiment data of gear box monitoring.

Abstract: Aiming to solve the problems in the non-linearity of thermistor temperature transducer, a compensate model based on neural network (NN) is proposed. The basic idea is using Fourier series as the basic functions of NN，the output of transducer as input samples of NN and the temperature as the expectation output of NN. The output of NN is used to approximate to the measured temperature by adjusting the weights. The results show the proposed method is effective in raising accuracy.

Abstract: Using diamond saw wire can incise the seabed oil compound pipes, and its state being incised can be monitored by measuring the tension of diamond saw wire, so, it makes the cutting and advancing velocities under the condition of harmony. At first the tension of saw wire was analyzed at its working condition, the mechanism of the tension sensor was designed by the method of composition of forces, and put forward the measuring method about tension of saw wire based on up-down single chip communications. Next, the tension sensor was designed and its detection principle was introduced. Its calibration and accuracy were carried out. In the end, the test of examining tension underwater was done and validated its feasibility and reliability. it shows that the value of tension changes between 40N and 60N basically when the cutting velocity is in harmony with the advancing velocity.

Abstract: This paper proposed a distributed iterative localization technology of wireless sensor networks (WSNs) to solve the problem of node localization. In this approch, once the nodes get localized, they act as references for the rest of nodes to localize. The ranging-based localization problem is formulated as a multidimensional optimization issue, and the quantum-behaved particle swarm optimization algorithm (QPSO) is used to exploit their quick convergence to quality solutions. Finally, the simulation results compared with the particle swarm optimization algorithm (PSO) algorithm show that QPSO outperforms the PSO and improve the node position accuracy, which prove the validity of the presented method.

Abstract: μAiming at the demand of missile fuse and other weapons systems, a high-g piezoresistive accelerometer with two terminal fixed beam-mass structure which can measure in-plane acceleration was designed. The design and simulation were also performed using Matlab and ANSYS. The simulation results show that the sensitivity of the accelerometer of sensitive-axis is 0.1101μV/g, and the transverse sensitivity of accelerometer is eliminated effectively. The key parameters such as impact over-loading signal and sensitivity of in-plane accelerometer were tested by Master hammer and Hopkinson bar. The test results showed that the sensor can work with the impact acceleration up to 117,395.95 g and the sensitivity of the accelerometer is 0.1028μV/g.

Abstract: The output characteristics of the variable pole pitch capacitive sensor is introduced, the relationship between non-linear error and range is analyzed respectively using theoretical fitting，zero-crossing rotation fitting and best uniform approximation fitting，theoretical expression is derived，and examples of calculations and MATLAB simulation are carried out. It has turned out that the expression based on the best uniform approximation fitting is more reasonable, having higher accuracy, and non-linear error is apparently reduced when the input of relative variation is the same; while in the given nonlinearity conditions, the range was significantly increased. To some extent, this provides theoretical guidance to the design and application of the variable pole pitch capacitive sensors.

Abstract: For the complex nonlinear property and a lot of regulatory parameter, it is difficult to design a reasonable magneto-rheological (MR) damper by simply process or experience. To solve this problem a structural optimization has been presented in this article. Three stages have been discussed in the article. By calculate the flux of MR fluid based on the yield stress of MR fluid, selected common design targets such as maximal output damping force, dynamic range and consult volume of damper has been presented in formula respectively with the parameter according to damper structure. By approximate the magnetic circle, the power of excitation also has been presented as an expression of structure parameter. An optimum method named multi-goal attach has been applied to solve the optimum problem. Finally some confirmation and experiment results have been presented. The experiment results indicated that the method presented in the article was effectively.

Abstract: Due to energy restrictions, node distribution density and hardware computing power etc., the traditional time synchronization mechanism is not suitable for wireless sensor network. The paper discussed the main reason that caused asynchronization and proposed an improved time synchronization algorithm based on cross layer optimization for wireless sensor network. Considering the stability of crystal oscillation and the linearity of crystal deviation in the physical layer, the improved time synchronization mechanism implemented a self-correction by the cross-layer MAC protocol. Estimating the crystal oscillation drift, the crystal deviation had been self-corrected just by a few times data broadcast. The experiment on the MCU Si1000 physical layer platform has demonstrated the practicability of the algorithm. The synchronization algorithm is able to keep a stable network operation in the way of extending the synchronization period and reducing the synchronization cost. The synchronization mechanism is applicable to the active acquisition network, especially the realtime one.

Abstract: This paper presents a novel Electromagnetic field (E-Field) probe structure employing a printed dipole antenna to get isotropic pattern. The printed dipole is constituted by a variety of orthogonal dipole antenna array, and it is used in the design to reduce the complexity and cost. In this paper, we stimulate the printed dipole antenna and detector diodes by software, and the results confirm the validity of the printed dipole antenna. Moreover, the directivity of antenna array depends on the location of dipole antenna. By changing some design of the antenna, the probe achieves flat frequency response in 0.1GHz-10GHz.