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Due to the shortcomings in the direct current model predictive control of the traditional voltage source inverters, output voltage’s quality is poor and waveform distortion rate is high. When the load changes, the tracking accuracy of the control system to the output current is not high, and there is a delay problem. In response to the above problems, the output accuracy is improved by adding voltage loop and feed-forward compensation of load current to compensate the load disturbance; solve the system delay problem by vector angle compensation method, solve the overshoot caused by current’s step change by load change, and improve current’s tracking accuracy. The optimal vector selection method is added to the cost function to reduce the switching frequency, reduce the output waveform distortion and improve power quality. Theoretical validity is verified by the simulation and theoretical comparison with the help of MATLAB/Simulink.

Based on the classic theoretical model of Diffusion-Limited Aggregation (DLA), two improved models, built for more practical use, were presented: Steps-Limited and Reaction-Limited three-dimensional Fractal Aggregation. The fractal dimension and porosity were calculated with cyclotron radius method, in order to study the influence of finite steps and reaction probability on the results of the fractal simulation of floc growth. A highly assembled aggregation would be formed as the Steps was getting smaller, contributing to the reduction of the cyclotron radius Rc which finally approached about 2.40, whose fractal characteristic became more and more inconspicuous. Smaller the reaction probability, the larger moving space of particles would be, resulted in the denser of the interior of the flocs, characterized by the gradual reduction of cyclotron radius Rc which finally approached about 2.65.

Catering to the new strategic project of smart grid, this paper introduces a design of high-voltage transmission inspection robot, which worked on earth wire and so that automatically inspection on the entire transmission line becomes the reality. Robot control system using hierarchical control structure, included remote management host, robot control ontology and motor drives. Under the auto-operation mode, it makes its own decisions for planning the sequence of operations according to knowledge data base without the upper layer's involvement. Using image recognition obstacle and expert data base, the combined method of using laser sensor over obstacles, the inspection robot autonomous obstacle had came true. The experiment and test results show that the inspection robot system has possessed the capabilities of navigation and inspection tasks on the power lines. It has a good application prospect.

The purpose of this paper is to explore theoretically the band structures for different kinds of point defect in phononic crystal thin plates for square / triangle lattice using the improved plane wave expansion method combining with the supercell technique. The defect is created by several means such as changing the radius, the mass density, the elastic modulus, the geometric shape of one of the cylinders, etc. The phononic crystal thin plate is composed of parallel cylindrical inclusion of Al 2 O 3 embedded periodically in the Epoxy host. The results show that the defect modes existing in the first band gap are strongly dependent on the size and the mass density of the point defect for the two lattices. Elastic modulus point defect could not lead the generation of the defect bands for the square lattice. However, for the triangle lattice, the elastic modulus has some influences on the defect modes. With decreasing of the size of the defect, all defect bands move from the upper edge of the first band gap towards the middle and the edges of the first band gap almost remain unchanged as the defect size varies.

A new aerial digital camera with wide-angle for low altitude unmanned aerial vehicle was developed in Chinese academy of surveying and mapping . This new camera can achieve high ground coverage and enlarge base-height ratio with a photographic system combined by four individual digital cameras. A complete overview is given for the composite camera system structure and the needed procedure for image post-processing is proposed. Another focus is drawn to the functional approach of setting up virtual image.

The band structures of bending waves propagating in the phononic crystal thin plates with point defect are explored based on the supercell technique combined with the improved plane wave expansion method. The plate is composed of a periodic array of circular crystalline Al2O3 cylinders embedded in the epoxy matrix for square lattice. The point defect is introduced by changing one of the cylinders' radii. The results show that the defect modes exist in the first band gap, the frequencies and the numbers of the defect modes are strongly dependent on the defect filling fraction and the filling fraction. All the flat defect bands appearing in the first band gap are nondegenerate. For a given defect filling fraction, there are up to five nondegenerate defect bands emerging inside the first band gap, and the frequencies of defect bands increase with the filling fraction increases. The defect bands disappear at very low or very high filling fractions. For a given filling fraction, three nondegenerate defect bands appearing near the upper edge of the gap move to the middle as the defect filling fraction is reduced, and the edges of the first band gap remain hardly changed. The study of the displacement distributions associated with the three defect modes shows that the flat bands correspond to the special localized frequencies of the waves. For the two lower defect modes, the displacement amplitudes around the defect are much bigger than that at or far away from the defect. However, for the higher defect mode, the displacement amplitude reaches the maximum at the location of the defect and decays rapidly with the distance away from that. Obviously, the bending waves correspond to such three modes are so localized at or near the defect that they can not escape into the surrounding phononic crystals. That is, the point defect behaves like a resonant vacant.

Adopting the decision tree technology, utilizing its process pattern that imitates human judgment and thinking and fault-tolerance features, the authors developed a decision tree classification method. Initially utilizing SPOT and TM, the work effectively enhanced LULC information and established the synthetic database; then, combining geoscience synthetic analysis with ground spectral feature information, utilizing the CART system; the authors built the decision tree model that is based on the decision rules. At last, we discussed the wild use of LULC decision tree classified and stratified extractive technology. Taking three counties in Hebei province as examples, we divided the research area to classify each unit (county area) by ecological division, utilized multiple data resources and geoscience rules to build the decision tree model and test and verify the method. The results demonstrated that the method improves the speed and precision of classification.

A low attitude photogrammetric system is developed in Chinese Academy of Surveying and Mapping, since the UAV (unmanned aerial vehicle) has advantages over traditional photogrammetric craft, such as small size, low weight, slow flight speed and extended range. This paper discusses calibrating method of an inexpensive 3 K by 2 K non-metric CCD camera used in this system. First,with 3D testified the self-calibrating bundle adjustment is adopted to determine the principal distance , the location of the principal point and distortion parameters of the camera. Secondly, a further distortion test was performed, this time with a planar 2D test field to create a digital distortion model. Moreover, the residual distortion error detection method is proposed by transforming and comparing the distortions obtained from the two calibration steps .