Applied Mechanics and Materials Vols. 373-375

Abstract: The purpose of health prognostic is to predict the future health status of system and determine the time from the current health state to functional failure completely. Application data time series analysis method often can get the expected prediction effect. Taking into account the failure characteristics of the actuators in flight control system, the autoregressive moving average model is introduced to health prognostic. The prognostic model is established. The simulation results show the effectiveness of the algorithm.

Abstract: With the development of modern agricultural science and technology, the phytotron, as a controlled environment laboratory, is applied widely in crop cultivation, breeding and other fields. Data acquisition and automatic control with high precision of microclimate parameters in phytotron becomes more and more important. In order to overcome the defects of conventional phytotron with complex layout and inconvenient maintenance, a new implementation scheme of monitoring system based on wireless sensor network for phytotron is presented in this paper. Different kinds of environmental parameters were collected by wireless node and sent to the monitoring center through wireless communication network, and then processed and controlled by the main controller collaborating with interactive interface equipment. Testing result shows that the monitoring system with friendly interface has advantages of high sensitivity, easy operation and flexible extension.

Abstract: In order to resolve the problem of complex wire routing, reliability and lightning-proof difficulty in automatic monitoring system of water conservancy engineering, the paper proposes a volume-compact, easily connected wireless strain collector. The collector modulates the differential strain signal by half-bridge and precise instrumentation amplifier, and employs an up-to-date RF system on chip to realize digitalization for analog voltage signal and wireless transmission. The wireless sensor nodes based on TI's Z-stack protocol possess high performances of network self-organization and network self-healing, and support low power consumption in wireless transmission by sleep mode.

Abstract: Tire pressure monitoring system (TPMS) is used to monitor fast or slow tire pressure loss or too high tire temperature, and ensure the safety of the drivers and the passengers. A new kind of TPMS as the core of MSP430F149 microcontrollers is put forward, which based on Wireless Sensor Network. It adopts Infineon SP370 new sensor as the transmitter and TDA5220 as the receiver. The whole system scheme, hardware and software design are expounded in this paper. A low cost, low power consumption and high precision TPMS is studied, and the tire pressure and temperature can be immediately and real-time measured.

Abstract: A cotton sliver detection sensor is designed, which is different from the traditional roller detection system. Firstly the lever enlarges the change of thickness of cotton sliver into a large amount of displacement, and then the LVDT detects this displacement, and finally the signal transmission module based on AD698 converts the detected signal of the LVDT into a voltage ranging from 0V to 10V. The experiments show that the sensor has good linearity and resolution. The design is not only with lower mechanical inertia and simpler signal processing circuit, but also solving the problem that in the face of processing technologies change, sliver sensor with embossing roller and ladder roller, need to replace the different detection roller.

Abstract: Study on the working principle of the surface acoustic wave (SAW) methane sensor. Establish the physical and chemical model of sensitive mechanism based on the mass-effect and the adsorption characteristics of gas on the sensitive membrane. The linear solvation energy relationship (LSER) has been developed to describe and quantify these various interactions. Simulate the mass-sensitive gas sensor based on COMSOL multiphysics software. The simulation significantly reduces the amount of prototype experiments, sensor development cycle and development costs.

Abstract: A high-precision pH sensor based on electrochemical principle is proposed in the paper. The principle of the sensor, the performance parameters of MCU, hardware architecture and experiment are introduced. The NEC microprocessor, which is low-power and high stability, is adopted as core processor. The three operational amplifiers same-phase parallel amplifying circuit not only matches the impendence of the pH combination electrode, but also eliminates the impact of wire resistance on pH measurement. The system's capacity of resisting disturbance is improved. Using 18-bit AD converter, which has programmable amplifier on chip, improves measurement accuracy. Both theoretical analysis and experimental results show the effectiveness of the pH sensor. A full description of the pH sensor and implementation are presented.

Abstract: It describes the basic principle of velocity parameters measuring of car in operation, establishes the related mathematical model. It disigns an intelligent, integrated digital solutions to combination instrumentation of the car based on MC9S12DP256B. This system has advantages of high performance, high precision, low cost, low power consumption, good stability, sensitive respond and expandability. The system measures and shows online velocity parameters of the car. It has fuction such as safety alarm. The system reserves bus interface such as SCI and CAN, correspondences easily with other electronic engine control systems of the car.

Abstract: In this paper, we propose a wireless sensor network self-location improved algorithm based on the Unmanned Aerial Vehicle (UAV). The path and the signal emission mechanism of the UAV are rational planning. The k-3 covering method is used to programming the working point and the path of UAV. We also set up a wireless sensor network localization experiment platform based on the UAV and then we carry on several experimentations and curve fitting on the surface-to-surface and surface-to-air distance curve. Experimental results show that the self-location system built based on the theories this paper proposed has an air-to-surface actual distance error of 4.42m and the algorithms positioning error is 3.67m which has very high work efficiency.

Abstract: Temperature is one of the most important factors affecting the accuracy of micromechanical silicon resonant accelerometer (SRA). In order to reduce the temperature sensitivity and improve the sensor performance, a new method of temperature self-compensation for SRA is presented in this paper. Utilizing the differential structure of SRA, the temperature compensation for bias and scale factor can be realized simultaneously in this method. Moreover, because no temperature sensor is needed in this method, the error in temperature measurement due to the temperature gradient between the mechanical sensitive structure and temperature sensor is avoided, and the precision of temperature compensation for SRA can be further improved. The test results obtained on SRA prototype which is developed by MEMS Inertial Technology Research Center show that, by employing the method of temperature self-compensation, the temperature coefficients of bias and scale factor are reduced from 3.1 mg/°C and 778 ppm/°C to 0.05 mg/°C and -9.4 ppm/°C, respectively.