Advanced Materials Research Vols. 468-471

Abstract: Remote sensing (RS) technology plays a most important role in forest fire monitoring. This paper reviews the application of satellite remote sensing, and introduces sensors which are commonly used for fire monitoring. The advantages and disadvantages are discussed by comparison and the paper specifically focuses on the application of RS based pre-fire forecast and pro-fire evaluation. With the help of this paper, the development of this technology could be well acknowledged, and it can therefore be believed that remote sensing would play a more important role in fire monitoring in the future.

Abstract: A simple and novel method to synthesize Er ion doped titania was investigated. In this work, Er-doped titania nanofibers were prepared by the sol-gel method. Characterizations of the nanofibers were done by X-ray diffraction, scanning electron microscopy. The results suggest that crystal structures of Er-doped titania composite nanofibers were changed due to Er ions disturbing.

Abstract: Accurately replying all queries of different users in Wireless Sensor Network is a challenging problem. The recent works solve this problem by approximate query based on sensor readings, For the need of precision, this model need to update frequently and the cost of communication increases very quickly. This paper proposes A sensor data query method based on wavelet synopsis, It constructs a wavelet synopsis in the process of data collecting, reduces the number of data, increases efficiency, reduces the communication cost.

Abstract: Parasitic motion of 3-PRS (prismatic-revolute–spherical) parallel mechanism is discussed, inverse kinematics model of this mechanism is established. Based on the structure feature of 3-PRS parallel mechanism, a new forward kinematics algorithm for this mechanism is presented. The algorithm consists of approximate calculation and iterative calculation. The mathematical model of the proposed algorithm is clear simple, no derivative operation or Jacobi matrix inverse operation is needed, so computation is less. The experiment shows that in the same computing environment, the calculation speed of the proposed algorithm is about 2 times of the existing algorithms to achieve the same accuracy, so it can be applied to real-time control. Complexity and workload of programming is less than half of before. The algorithm is based on 3-PRS parallel mechanism, but it is also applicable for other parallel mechanism.

Abstract: To solve the problem that in excitation control system the parameters of proportional integral differential (PID) controller are difficult to be set, a summary on research results of current synchronous generator excitation control regulator parameters optimization. The article details the PSO algorithm of synchronous generator excitation control principles, and whose advantages and disadvantages. For the PSO algorithm converges slower early and late defects iteration, it introduces a new algorithm called adaptive chaotic particle swarm optimization (CAPSO), and using the chaotic tent mapping-based search methods to achieve improvements in partly-search, with a strong and robust search capabilities for the industry and scholars for reference.

Abstract: This paper describes an nonlinear three-dimensional (3D) inversion algorithm for reconstructing a homogeneous dielectric target in an anechoic chamber in a controlled environment. The applied algorithm is a nonlinear iterative algorithms—two domain integral equation based method, namely the contrast source inversion (CSI) algorithm. The inversion results, which are presented and compared for the co-polorized data using the multi-frequency multi-bistatic measurements, verify the capability, the accuracy of the CSI algorithm for 3-D microwave imaging.

Abstract: Methods：In this paper, a new anatomic contour extraction algorithm based on the contourlet transform and pulse-coupled neural network ( PCNN ) was presented. The contourlet transform is applied on the vertebra CT image firstly, using its multiscale and multidirectional characteristics to get the coefficients which can effectively capture the contours of an image and depict the contours sparsely. Then PCNN is utilized to extract contours from the contourlet approximation image. Finally, the contours of image are reconstructed by inverse contourlet transform.Results：The proposed algorithm is tested on vertebra CT images, and we get some encouraging results, which are better than those based on wavelet. Conclusions：In this paper, we extract the contours of vertebra correctly, which effectively represent multiscale and multidirectional singularities of an image. This proposed method is very significant for the clinical applications and medical researches.

Abstract: ZigBee is an emerging shortrange wireless network technology which based on IEEE802.15.4,but increase in nodes and forwarding data packets significantly reduces the network life cycle.First analysis the two basic routing algorithms in details,then two advanced algorithms resulting from node energy are proposed.The simulation of performance using NS2 indicates that in the same condition the improved routing algorithms can reduce the death of nodes and prolong the network life cycle.

Abstract: Overhead cranes are essentially a kind of complex underactuated nonlinear mechanical systems, and it is a challenge to design an anti-swing controller for overhead cranes, hence, many people design controllers of overhead cranes ignoring the changing of the rope length and other parameters. In this study, we propose a multi-sliding mode controller to solve the problem of anti-swing and positioning controller for an overhead crane with rope length variations. This controller can provide a simultaneous trolley-position regulation, sway suppression, and load hoisting control. Also, this paper adopts a new method to decrease the chattering of the control input. Stability analysis of the proposed controller is given in the paper. The proposed controller does not rely on the accurate knowledge of overhead crane system model, and it is simple and easy to apply, and robust to disturbances. The simulation results show the good performance of the proposed controller.

Abstract: An equivalent method that simulate drainage holes is adopted in the analysis of 3-D seepage field. The Initial Flow Method is applied in this paper to deal with the unconfined seepage problem. In this paper, the finite element model of a gravity dam project is established and the seepage field is analyzed.