Applied Mechanics and Materials Vols. 333-335

Abstract: Global ontology and local ontologies can be built to effectively implement data semantic access in integration environment of multiple data sources based on grid computing. Data sources, as a kind of resource in grid, can join and quit grid environment dynamically. In order to ensure consistency between global ontology and local ontologies, we present joining and quitting algorithms for data sources in grid system. During processing of joining and quitting algorithms, global ontology elements were divided into two types of AES(Active Elements Set) and SES(Suspended Elements Set),and we stipulate that only mappings formed by AES can be employed for semantic data processing.

Abstract: The shearlet plays an important role in image processing because it can provide optimally space representations for higher functions. In the note, a sufficient condition for irregular shearlet frames with several generators is presented. This generalizes the existing result to the case of several generators.

Abstract: With the increasing of fault information transmission capacity in power grid, the volume of information which needs to be concerned by dispatchers has greatly increased, consequently making it difficult to identify the fault signal and analyze the cause of the accident quickly for dispatchers in massive fault information. To settle this problem, this paper uses a novel approach that combines rough set theory with association rule for mining fault rules in a large number of historical fault data of power grid. Firstly, it builds distributed original decision tables according to regions. And then it uses the information entropy algorithm in condition attribute reduction. Lastly, it applies the improved Apriori algorithm of association rule to fault rules mining based on the reduction decision table. In this way the problems of redundancy of massive fault information can be solved and complexity of rules extraction can be simplified effectively. It also improves the efficiency of fault rules mining.

Abstract: In the long-running process, SCADA system have accumulated a mass of the grid off-limit information, if we idle this information, will lead to so called resources deserted, at the data level, through data mining tools, we can have a correlation analysis of the off-limit information accumulated in the grid fault history library, to dig out the law, in a certain sense, the law can be the criterion for the grid Warning Decision Support.

Abstract: The digitization construction of scenic spot, a part of intelligent tourism, has aroused wide concern and achieved some successes. But problems still exist, for distance, the display of tourism information is incomplete, interactive experience is poor and intelligent management is unattainable. In essence, digital scenic spot is an intellectualized and visualized area supported by 3s technique, Multimedia technology, virtual reality technology, etc. Applying virtual reality into the tourism is a wonderful measure, which favors the promotion of digital scenic spot, dynamic planning and online virtual tour. Based on discussing the status of application of virtual reality, the paper puts forward some suggestions about ideas, platform and system for its further construction.

Abstract: Sophisticate mathematic computation is used when the residual error parameters are estimated employing time domain technique. This paper discuss the improved method of employing Window function before the inverse Fourier transform. At the same time, we find the curve of time domain will be out of the standard shape when the linear prediction of the measured signal section is too long, and some figures are offered to illustrate it.

Abstract: In order to provide higher accuracy performance in navigation and positioning requirements, modernized navigation signals with more complex structure, such as MBOC or AltBOC signal, have been actively researched and used in the modernized GPS system, like emerging Galileo and BD-2 system. For the navigation signal simulator which generates those modernized signals, traditional bipolar BPSK or QPSK signal generation method cannot permit to generate those multi-level signals successfully and different modernized signals flexibly. After analyzing the current public modernized signal structure, a novel configurable signal generation method for generating the modernized navigation signal has been proposed. The amplitude quantization word-length and phase truncation error of the LUT (look-up table) used by the method have been analyzed. Experimental simulation results demonstrate the correctness and efficiency of this new method.

Abstract: Huffman coding is a statistical lossless coding method with high efficiency. The principal and implementation of Huffman coding is discussed and Huffman coding is implemented to the compression of vector maps. The property of the algorithm is discussed. Experiments demonstrated that the algorithm proposed can compress vector maps with high efficiency and no loss.

Abstract: The existing test method for properties of UAV data-link is usually the actual flight test or field "distance" test, which has long test cycle and difficulty for the extraction of test data. In view of this situation, we in this work adopted the data-link semi-physical simulation test platform based on darkroom calibrate-link method, establishing and analyzing the space natural decline model, atmospheric environment model, and aircraft attitude angle model that affecting the transmitting and receiving of signals. Meanwhile, the average delay from-terminal-to-terminal and the fluctuation of the average delay of the UAV under different MAC channel access protocols are discussed using the darkroom calibrate-link method. In order to improve the response characteristics of the UAV, time delay is compensated using optimal control methods, and the effectiveness of the compensation method is validated based on and the platform we built. The simulation results show that, the design of UAV data-link can be calculated by this theory, and the introduction of the optimal control method significantly improves the dynamic response characteristics of the UAV.

Abstract: The principles and methods of chaos generation are researched using piecewise linear circuit theory. The chaos generation circuit based on integrated operational amplifiers is designed to realize chaos. Simulation results of the circuit are got using Multisim software. It indicates that using this method, the relationships and laws between chaos and various circuit element parameters can be better found out.