Advanced Materials Research Vols. 383-390

Abstract: For meeting the needs of the survey of agriculture environment communication in Hainan Province, an intelligent monitoring system was developed based on ZigBee which consists of four parts: wireless sensor networks, gateway, transmission network, remote monitoring center. A new type network structure which is composed of wireless sensor networks and the transmission network was proposed. This paper is devoted to explanation and illustration for our design of intelligent agricultural monitoring system. The system feasibility and superiority was verified in a simple star topology setup in a botanical garden in QiongZhou University. The sensor nodes can obtain the temperature, humidity and illumination information in real time, and then transferred to the remote monitoring center by the gateway via the transmission network. The test result shows that this intelligent agriculture monitoring system has the useful characteristics of low power consumption, low cost, large network capacity, flexible disposition, and minor influence on the natural environment. It has better actual application value.

Abstract: This paper introduces a Hopfield neural network theory to deduce the model of the detection of fractional harmonic. It also discusses the setting method of integral parameter. The simulation results show that the method has high precision and the dynamic characteristics of the system are relevant to the integral parameter.

Abstract: Iron-Core coils based electronic current transformer is often used with electrical measuring instrumnts and meters. However, the iron-core coils used as the primary current sensor have nonlinear behavior, and its magnetizing current can be considered as the main error source. Therefore, a nonlinear compensation approach for the iron-core coils based electronic current transformers is proposed in this paper. The approach depends on a linear hardware circuit and a nonlinear numeric control law. Theoretical analysis and experimental results have verified the correctness of the proposed method.

Abstract: A new practical fault location algorithm using two-terminal electrical quantities is presented in this article, which takes into account the distributed parameter line model. The analytical expression of algorithm derives from Three-Phase decoupling. First, an analytical synchronization of the unsynchronized measurements is performed with use of the determined synchronization operator and the non-synchronizing angle is calculated with the two-terminal pre-fault electrical quantities. Then, the real-time transmission line parameters are calculated using two-terminal non-synchronized electrical quantities and the non-synchronizing angle. The algorithm overcomes the drawbacks of the traditional fault location algorithms, which does not exist the pseudo-root problem. Besides, it has the advantages of simple, practical, litter computation, no need to search and iterative and robustness. The algorithm has not influenced by fault types, the transition resistance and other factors. At last the developed fault location algorithm is tested using signals of ATP-EMTP versatile simulations of faults on a transmission line.

Abstract: An analysis for controlling a static-unstable tactical missile using two-loop acceleration autopilot was detailed. The rate feedback loop was firstly presented. The equivalent actuator dynamics was introduced and examined. Thus an overall stabilization condition combined with both low and high frequency cases was proposed. The lever effect led by inertial measurement unit was of benefit to a great controllable range. The results show that the autopilot control capacity is dominated by actuator bandwidth, and a compromise should be determined between the flight performance and the actuator requirement for a static unstable tactical missile.

Abstract: An improved TS algorithm is put forward on the condition that reactive power compensation location and capacity have been identified in rural distribution lines. The Algorithm is based on capacitor optimal on-off model aimed at a minimum network loss, it can control the capacitor on-off according to the load changing and the system operation status and keep real-time voltage qualified and network loss minimum. A distributed control system is designed by using the algorithm to realize reactive power optimization, which is composed of reactive power optimal terminals and background control center. The terminal is in charge of data collection and transmission, on-off instruction receiving and executing. The control center in in charge of receiving data from every compensation point, calling control algorithm to process data, forming and sending instructions. GPRS technology is adopted to realize the system’s foreground-background communication. The actual application in some experimental networks has proved that the system can realize global optimal control for distribution lines, and is suitable to be widely used in rural distribution network.

Abstract: The system identification problem of Multi-Input Multi-Output fractional order systems with Time-Delay is studied. A Frequency-Domain identification algorithm is presented, which combines genetic algorithm and subspace method for fractional order systems with time-delay in state. The genetic algorithm is used to identify fractional differential order and Time-Delay parameter. And the state space model is obtained by using frequency-domain subspace method when fractional differential order and time-delay parameter are fixed. Numerical simulation results validate the proposed algorithm.

Abstract: In this work, stability analysis of the Fractional-Order Arneodo system is studied by using the fractional Routh-Hurwitz criteria. Furthermore, the fractional Routh-Hurwitz conditions are used to control chaos in the proposed fractional-order system to its equilibria. Based on the fractional Routh-Hurwitz conditions and using specific choice of linear feedback controllers, it is shown that the Arneodo system is controlled to its equilibrium points. Numerical results show the effectiveness of the theoretical analysis.

Abstract: The theoretical backing of the similarity laws obtained from dual dimensionless parameters of the bed-form classification diagram is given by solving the equations of similarity conditions which is obtained from 1-Dimensional equation of motion, continuity equation, bed deformation equation and the formula of bed load transport. Secondly, the validity of the similarity laws is confirmed by comparing the bed form of distorted model experiment with that of undistorted model experiments performed by Hokkaido Development Bureau (H.D.B.). And also the fact that the height of bar in a gentle curved river channel can be estimated by the result of distorted model of straight flume is found.

Abstract: Zero crossing points of Back-Electromotive force (EMF) is the most mature and widely used method of the speed sensorless control of brushless DC motor (BLDCM). However, with the poor performance from standstill to low speed, it is not suitable for the position servo system. Therefore, this paper first analyzes several conventional speed sensorless control schemes in the BLDCM, then presents a novel control algorithms for the BLDCM. In the proposed method, the short pulse sensing method for the rotor position in the Start-Up process and self-synchronization with zero cross points of back-EMF are combined together. As a result, the BLDCM used in the position servo system can be easily controlled from zero to high speed, the theoretical analysis is verified by the simulation results based on Matlab, it shows that the proposed algorithms can improve the performances of position servo system compared with the conventional methods.