Abstract:Formulas of the incremental interface element method for viscoelastic materials are deduced in the interface element model. The numeral example shows that the viscoelastic interface element method is effective in the analysis of viscoelastic discontinuousness medium.

Abstract:The modeling & simulation of the flying performance of helicopters is developed here in order to maintain them based on their states. It is centered on the modeling of the working characteristics of the turboshaft. First, the descriptions of the flying performance of helicopters and the characteristics of the turboshaft are discussed, and a math model of the working process of the turboshaft is built. Then the model is predigested according to the calculating program of the engine's test performance. Finally, the flying performance simulation is realized through the calculation based on the simplified model. The results show that this method is credible and high efficienct.

Abstract:At present, micro-spacecrafts are being developed. Micro-nozzles are very important in propulsion systems of micro-spacecrafts. So further study on micro-nozzles is essential. DSMC(direct simulation Monte-Carlo)calculations for the flow in axisymmetric micro-nozzles are conducted on molecular-based models. The influence of the mass flow rate and dimension on the flow and performance in the nozzle are also discussed. The study indicates that the mass flow rate and dimension of the nozzle have different degrees of influence on the flow and performance.

Abstract:Silicon carbide fiber reinforced silicon oxycarbide(Si-O-C) composites are fabricated via precursor infiltration and pyrolysis using polysiloxane . The results show that bending strength of ceramic matrix composite are 255.2 MPa、309.0 MPa at pyrolysizing temperature 700℃、800℃, and 45.3 MPa at pyrolysizing temperature 1000℃. Microstructure、properties and load/displacement curves of SiC_f/Si-O-C composites are studied and discussed.The high properties are mainly attributed to the ideal interfacial structure.

Abstract:The HLA-based simulation application system is an efficient approach to increase the efficiency of the combat simulation. The structure and characteristics of the missile-combat simulation system are analyzed first. Then, based on FEDEP of DMSO and experience of the authors, the general process of developing the HLA-based simulation application system is studied, which can be described in four steps: system analysis, federation design, FOM/SOM development and federate realization. In the end, an example, the design of the missile-combat simulation system between the ground-to-ground missile and the aegis system, is given.

Abstract:In order to investigate the penetrating characteristics of earth penetrating weapons, a series of simulation experiments have been performed on 57mm diameter gas gun by launching long rod projectiles penetrating three kinds of concrete targets. These concrete targets are cement mortar, steel fiber reinforced concrete(SFRC) and the SFRC with a board made by tightly arranged corundum spheres inside. The experimental results indicate that the nose shape has important influence on the penetration depth, while targets are impacted by the same projectiles at the same velocity. The penetration depth into SFRC with the board is decreased about 11%, but the penetration depth into cement mortar is increased about 12% as compared with that into the SFRC.

Abstract:The experiments of small scale projectiles penetrating SFRC targets are performed on the 57mm diameter light gas gun. They are intended to investigate the performance of the projectile penetrating into the steel fiber reinforced concrete (SFRC) targets (volume percentage of 5). The impacted crater shapes of SFRC targets are observed, and the velocities of projectiles impacting the targets are measured. The crater volume of the targets is measured by the pouring sand-filling method, and the penetration volume is calculated. The relation between the kinetic energy of the projectile and the penetration volume is obtained. The kinetic energy of per unit penetration volume and the impact kinetic energy per unit cross section are introduced to review their relation by dealing with the experimental data.

Abstract:The micro air vehicle is a growing field of new aircraft and its control is a challenging key technology in the MAV research. Summarizing MAV, this paper presents a survey of the current situation and development of MAV flight controller, and analyzes some key tech problems in the design of MAV flight controller, which includes the scheme of flight control, on-board sensors, new control device, flight control algorithms, and controller design methods.

Abstract:The OFDM system has a very good performance on antimultipath. We illustrate the principle of antimultipath and analyze the impact of the multipath channel on an OFDM signal spectrum in two cases. Then we discuss the algorithms to reduce it. In a two-path channel, we simulate the OFDM system based on HiperLAN Type2 PHY protocol and analyze its performance. In the end, we offere some proposals for improving the performance of the system.

Abstract:Using the function approximation characteristic of RBF-neural network, a new algorithm of estimating the background is proposed. Based this algorithm, a new means to detect the infrared small target is found. Here, two kinds of infrared images, one with a small target in it and the other without the target, are tested in the simulated experiments. The result of the experiments proves the good performance of the proposed algorithm.

Abstract:The key problem for reentry vehicle (RV) discrimination during the reentry phase is to estimate the mass-to-drag ratio of RV precisely and rapidly. Aiming at the nonlinear characteristic of reentry process, three filters：as spline Kalman filter, extended Kalman filter and a new extended Kalman filter based on “unscented transform” are studied. The comparison of estimating performance for these filters are provided through simulating experiment with terms of estimating precision and converging speed. Experimental results show that the new EKF based on “unscented transform” has the best performance on the estimation of mass-to-drag ratio.

Abstract:In view of the fact that BP algorithm based on the common used error square sum rule and Sigmoid transfer function have some limitation and shortcomings, the cross entropy rule and a new transfer function are adopted for constructing and training process of the fuzzy neural network classifier. It is used to realize the orientation of myocardial infarction, and the results prove that this classifier has the capability of outperforming the traditional fuzzy neural network in training efficiency and recognizing ability obviously.

Abstract:Topological relationship is a very important spatial relationship in geographical information systems (GIS). During the past decades, many models that distinguish topological relationships have been proposed. But these models cannot distinguish the topological relationships between heterogeneous geometrycollection objects, which are composed of different dimensional geometries. We introduce the formal definition of mixed geometry and regularization rules. Base on the spatial model and Dimensionally Extended Nine-Intersection Model (DE-9IM), we propose a topological relationship model—Integrated Dimensionally Extended Nine-Intersection Model (IDE-9IM). The model can distinguish not only the topological relationships between single points, lines, areas, and/or homogeneous geometrycollection objects, but also the topological relationships between heterogeneous geometrycollection objects by considering the whole objects and the components of the complex objects. So IDE-9IM can be taken as a unified model of distinguishing topological relationships between arbitrary spatial objects.

Abstract:Naǐve-Bayes algorithm is a stable supervised learning method, and it is difficult to improve its predicting accuracy. This paper analyzes the properties of the error-correcting output codes generated by search-coding method at first, then presents a search coding based on vaǐve Bayes algorithm (SCNB), and describes the flow chart of SCNB in detail. Experimental results show that search-coding method is an efficient approach to improve the generalization for Bayesian classifiers.

Abstract:Computer simulation of special effect is an important part of the visual surgery simulation system. Rapid and accurate simulation of special effect can make the visual surgery more realistic. Simulation of bleeding is essential to surgery simulation system. This paper focuses on small amount bleeding appearing in a small injury. It forms a bended bloodstream on the organ surface. A simple model is established. The bloodstream is rendered by the metaballs method. During the simulation, only the dynamic simulation of the leading end of the bloodstream is considered while the rest of the bloodstream is rendered statically. This combination of dynamic simulation and static rendering can reduce the expense of computation and make the model more real and more computationally efficient for real time animation.

Abstract:WebLearning-plus is a multicast-based collaborative learning environment we developed, in which scalable video coding and adaptive multicast transmission are the key issues. According to the demand of adaptive video multicast in WebLearning-plus for the coder, we present a new scalable wavelet based video coding approach named ViCowel, which is a kind of set partition based on line scanning. Experiments show that it has better flexibility in video multicast applications.

Abstract:This paper first makes a study of the shape variation laws of generic planar parametric curves by means of geometry deformation, obtains a necessary and sufficient condition for a curve's occurring inflection points and a functional equation to determine the inflection points on the deforming curves. Then based on the results, the paper puts forward a method to study the inflection points on NURBS of non-convex control polygon, particularly makes an investigation on the distribution of inflection points on the curve whose control polygon is regular and with one to two inflection points, and gains several conditions and criterions for analysis and manipulation of the respected NURBS curves. The results are useful for the algorithm-design and shape-control in CAD modeling.

Abstract:For the phase of product configuration in modular design, a process of product module configuration set is put forward based on the feature parameter model of module family. A detailed description is offered on how to generate the mapping relation from user requirements to module feature parameters through Quality Function Deployment (QFD) method. According to this relationship, a model of similarity metrics is adopted to retrieve modules from module base. Hence, a complete approach for constructing product module configuration set and product configuration scheme is offered.

Abstract:With the background of collaborative 3D-CAD design, the paper probes into the detection of the conflict in the real-time collaborative design, and presents an idea that data confliction in real-time collaborative 3D design is entity feature confliction. According to this idea, the paper discusses the conflict detection methods based on feature. By analyzing the shortcomings of the methods, the paper provides a geometry level conflict detection strategy with higher feasibility as well as its timing sequence scheme. The conflict detection data structure and conflict detection rules are also studied. This conflict detection idea has been validated in the Pro/ENGINEER platform of PTC Corporation and a better conflict detection result is achieved.

Abstract:The flexible joint is the key component of dynamically tuned gyro (DTG), and its rigidity is a very important parameter. A dynamical angular rigidity measuring method is given based on modal analysis. It excites the flexible joint with step excitation, and measures the vibration with laser sensor and acquires the vibration data with the data acquisition card, then has the digital filter, fast fourier transform (FFT) and spectrum zoom, calculates the dynamical angular rigidity of the flexible joint; simultaneously the dampness ratio coefficient is obtained. The method solves the problems which brings about static rigidity test of the flexible joint, and has the characteristics of high precision, convenient operation, high efficiency and good repeatability.

Abstract:A general hierarchical framework of news video process is presented. It divides the news video process into three levels: syntax segmentation level, semantic labeling level and abstraction level. Some key techniques related to these levels are described and solutions of them are introduced. The proposed framework overcomes the shortcomings of traditional news video process methods, which are limited to the content-based segmentation and process based on the single media feature. It acquires the semantic content by the analysis of audio-visual features synthetically. Experiments are carried out on a news video process prototype called NVPS, which validates the feasibility of the framework. Three methods, namely story detection, caption detection and anchor detection methods are tested on NVPS. The results reach to the detection precision of 88%, 86% and 86% respectively, which prove the efficiency of the layered framework in the semantic content analysis of news videos.

Abstract:A 3-D nonlinear contact analysis model with several teeth pairs in meshing which is used to simulate a pair of cylindrical helical gear in the large power shipborne reducer is established by the direct constraint method provided by MSC.Marc. Then, based on the model, a quasi-static analysis is carried out in a meshing period. The numerical results show a very good agreement with the meshing rules in reality, and simultaneously, the rationality of the model is verified. Because of the original traits, the model can be used to be deal with the dynamic meshing problem of the gear pair.

Abstract:The TSP is a classic combinatorial optimization problem. According to the character of the optimal tour of Euclidean plane TSP problem, the sub-path and related notions are presented. A tour construction algorithm is designed by using convex hull, and a genetic algorithm is improved to solve the problem by using Delaunay triangulation diagram as heuristic information. The experimental results in the 144 cities in China and other TSP instances show that the algorithm is effective.

Abstract:The principle of micro-zooming is analyzed in the spatial domain. Micro-zooming is the method that changes imaging focal length of the optical system gradually to obtain a series of images of the same scene with different amplified multiples, and reconstruct a high resolution image through these images. It can be used to realize superresolution imaging of opto-electronic imaging systems. Micro-zooming imaging can be equivalent to change the area and position of the sensor element's corresponding object radiance distribution region, which are related to the magnification and the location of the sensor elements respectively. So the spatial model can be established and the relationship between the observed images and the ideal high resolution image can be given as linear equations. The high resolution image can be obtained by solving the equations. The experiment of the superresolution imaging of area-array CCD by micro-zooming is described in the end of the paper. It denotes that the resolution of the image increases markedly.