Applied Mechanics and Materials Vols. 475-476

Abstract: We developed a sensor module by using various commercial sensors and a wireless communicating module. The sensor module can be used to monitor an indoor environment via its temperature sensor, humidity sensor, light sensor, odor sensor and atmospheric pressure sensor. We also designed a user interface for a tablet PC. While communicating with the sensor module wirelessly, the data of an indoor environment were collected in real time. Using the environmental data, we calculated the Wet Bulb Globe Temperature (WBGT) and the discomfort index (DI) to determine the threshold values of an indoor environment for preventing heat illness and to obtain information on environmental quality.

Abstract: To handle the state estimation fusion problem between local estimation errors for the system with unknown cross-covariances and to avoid a large computation complexity of cross-covariances, for a multi-sensor linear discrete time-invariant stochastic system with time-delayed measurements, by the measurement transformation method, an equivalent system without measurement delays is obtained, and then using the covariance intersection (CI) fusion method, the covariance intersection fusion steady-state Kalman estimator is presented. It is proved that its accuracy is higher than that of each local estimator, and is lower than that of optimal Kalman fuser weighted by matrices with known cross-covariances. A Monte-Carlo simulation example shows the above accuracy relations, hence it has good performances.

Abstract: The article firstly introduced the work principle of a cable type of displacement sensor. Then it analyzed that design, calculation and selection of the scroll spring and the rope which was used for the sensor designed. Experimental verification shows: with high measurement precision and good wear resistance, the designed sensor has a good value of research and application. The cable displacement sensor designed can be used in engineering machinery, automatic control system length measurement and position measurement.

Abstract: This paper investigates the problem of designing covariance intersection fusion robust time-varying Kalman filter for two-sensor time-varying system with uncertain noise variances. Using the minimax robust estimation principle, the local and covariance intersection (CI) fusion robust time-varying Kalman filters are presented based on the worst-case conservative system with the conservative upper bounds of noise variances. Their robustness is proved based on the proposed Lyapunov equation, and the robust accuracy of time-varying CI fuser is higher than that of each local robust time-varying Kalman filter. A two-sensor tracking system simulation verifies the robustness and robust accuracy relations.

Abstract: This paper deals with the problem of designing covariance intersection fusion robust steady-state Kalman smoother for multisensor system with uncertain noise variances. Using the minimax robust estimation principle, the local and covariance intersection (CI) fusion robust steady-state Kalman smoothers are presented based on the worst-case conservative system with the conservative upper bounds of noise variances. Their robustness is proved based on the proposed Lyapunov equation, and the robust accuracy of CI fuser is higher than that of each local robust Kalman smoother. A Monte-Carlo simulation of three sensors tracking system verifies their robustness and robust accuracy relations.

Abstract: Based on the standard Kalman filter, considering the actual problems of the sonar altimeter is susceptible to the environment and its accuracy is poor, put forward a kind of adaptive algorithm based on n iterations to adjust observation noise. By adjusting the observation noise covariance, to make it more close to the actual value, so as to improve the accuracy of the altimeter data. Experiment show that the algorithm is effective.

Abstract: The basic composition and working principle of the intelligent control system of LED lighting was studied in this paper. And the two feedback control adjustment methods of this control system were researched deeply. Details including working principle and typical applications of light-sensitive sensor in feedback control part of this control system were studied. The content of this paper had great significance for the design of the intelligent control system of LED lighting.

Abstract: As there is no round optical grating and magnetic grating with large diameter that is over 0.5m in the market, a measuring system adopting dual magnetic sensors based on FPGA is proposed in this paper to measure the position/displacement and velocity of the rotating outer-rotor motor. Through using strip-type magnetic grating to stick around the outer rotor over half circumstance, the proposed system is able to produce continuous position pulse signals by switching the signals of dual magnetic sensors. The system core chip distinguishes, subdivides and filters the signals from two sensors, judging the operational state of the sensor and generating the dual magnetic sensor switching signals. It can switches the sensor signals in real time during motor operation and measures the position/displacement and velocity of motor in a precise manner. Moreover, the position/displacement, operating time and positive/negative rotation can be displayed through man-machine interactive unit. The experimental results show that arc-second control accuracy of the outer-rotor torque motor can be achieved by using the proposed system to measure the speed and position/ displacement of the outer-rotor torque motor as the feedback signal through the motion control system of motor.

Abstract: According to the energy constraints characteristics of Wireless Sensor Networks, how to optimize clustering, reduce the node energy consumption and balance the network energy dissipation is an main target, we proposes an Energy Efficient Clustering protocol based on Niching Particle Swarm Optimization (NPSO-EEC), the algorithm considers the factors such as the nodes residual energy and neighbor nodes status, etc. The simulation results show that the proposed protocol can balance the nodes energy consumption effectively, reduce the sensor nodes death rate, and prolong the network lifetime.

Abstract: Manganese oxide electrode (MnO₂) is a promising reference electrode imbedded in concrete for long-term health monitoring of concrete structure. The MnO₂ electrodes made of the high purity graphite powders, the MnO₂ powders and Ca (OH)₂ powders mixed with the inner alkaline electrolytes such as saturated Ca (OH)₂ solution or synthetic concrete pore solution are manually assembled. The rejection ratios, reproducibilities, stabilities and the effects of temperature and NaCl concentration in outer electrolyte (synthetic concrete pore solution) on potentials of the MnO₂ electrodes are comparatively experimented. And then the comprehensive properties of the MnO₂ electrodes are analyzed based on their potentials relative standard error (PRSE). Though the relative high rejection ratio of MnO₂ electrode is induced by the manual method, the following results and conclusions can be drawn. Firstly the MnO₂ electrodes express good performances with little potential fluctuations in outer synthetic concrete pore solution. Secondly the potentials under condition of certain temperature or certain NaCl concentration, the reproducibilities and stabilities of MnO₂ electrodes are influenced by their inner alkaline electrolytes. Especially the potential of the MnO₂ electrode with the inner saturated Ca (OH)₂ solution in outer electrolyte with high NaCl concentration is more outstandingly stable than the one with the inner synthetic concrete pore solution. The third the MnO₂ electrode with inner synthetic concrete pore solution has better comprehensive property than the one with inner saturated Ca (OH)₂ solution when the temperature is less than 50 °C or the NaCl concentration is not greater than 0.1 mol/L in outer electrolyte.