Abstract:The granular flow models on the basis of the kinetic theory are presented for numerical study on a dense particles bed with shock interaction. For the solid phase, the constitude equations are deduced from the interactions between the mean and the fluctuating motions of solid particles,the latter are represented as functions of the granular flow temperature. Numerical simulation by the AUSM⁺ schemes is employed to analyse the flowfield of the shock-induced fluidization of inert powder layers. It shows that the granular flow models are feasible to describle the flow with high speed and strong discontinunity.

Abstract:This paper brings forward the principle of designing three satellites cluster for time-difference localization according to the analysis of positioning precision. It analyses the geometry transformation of the cluster, and discusses the design of global localization cluster. An efficient designing method is given in the end. It is proved by simulation that the satellites cluster designed by this method can provide global high-precision localization.

Abstract:According to the conservation of flux on the zonal boundary,a two and three dimensional zonal boundary schemes are derived for patched grid systems.Based on this work,a multizonal numerical algorithm is developed for 2D/3D viscous complicated flow field with supersonic jet.Using this algorithm,the Launch Escape Vehicle (LEV) jet interaction viscous flow field is numerically simulated with angle of attack of 4°and 8°.

Abstract:A numerical method has been developed to solve the three dimensional Navier-Stokes equations and the numerical procedure uses Osher-Chakraverthy's TVD scheme for the inviscid flux and central difference scheme for the viscous flux. LU-SSOR method is used to solve the resulting systems of discretized equations and the Baldwin-Lomax turbulent model is used. Numerical solutions of three dimensional hypersonic jet interaction flow field with angle of attack of 5° is obtained and experimentally validated this numerical result at KD-01 gun wind tunnel. By validating, some problems of numerical simulation are studied.

Abstract:The reliability demonstration testing procedure for Weibull distribution is discussed.First,the noninformative prior distribution of the parameters of the life distribution is derived.Then the prior PDF(Probability Density Function) of these parameters are given combining with prior information according to Bayesian theorem. Finally,the reliability demonstration testing procedure is analyzed taking into consideration the consumer's profit and producer's profit. The simulation results show that the consumer's profit and producer's profit can be compromised.

Abstract:The method applied to sphere-cone pressure prediction has been extended to calculate pressure distribution on sphere-bicone vehicles in supersonic/hypersonic flow field. The results under various flow conditions compare favorably with numerical flow field solutions and the wind tunnel test data.

Abstract:This paper reports the analytic and numerical results of persistent currents in one-dimension mesoscopic rings with the free electron model by taking spin into consideration. Extending to three-dimension ,the theoretic result is close to the experiment result. The article introduces theoretically the modulation by spin for the first time.

Abstract:For the choice of electromagnetic field boundary conditions in particle simulation of plasma,the simple absorbing boundary conditions, Lindman boundary conditions and super absorbing boundary conditions are discussed in detail.The results show that the computing quantity is the least and the error is the most for the simple absorbing boundary conditions, the computing quantity is the most and the error is the least for the super absorbing boundary conditions, and the error is less and the reflectance is little affected by the angle of incidence for Lindman boundary conditions.

Abstract:The physical problems concerned with the calculations of the radiative opacities of high temperature plasmas are presented, the emphasis being placed on such atomic processes as bound-bound transitions, bound-free transitions and the autoionization resonance broadening. Various broadening mechanisms related to the calculations of the bound-bound absorption are also discussed. The theories of the calculations of the radiative opacities of high temperature plasmas using detailed-term-accounting (DTA) approximation have been introduced. The theoretical results are compared with the experiments. Emphasis is placed on discussing some of the results we have obtained recently.

Abstract:Noise in dynamical systems is usually considered a nuisance. But in certain nonlinear systems, the presence of noise can in fact enhance the detection of weak signal. This phenomenon, called stochastic resonance (SR), may find useful application in physical, technological and biomedical fields. A novel approach to detecting weak periodic signal using stochastic resonance theory is presented. This method is analyzed and validated by simulated signal. The result shows that this method is simple, robust and reliable. The weak sinusoid signal of lower signal-to-noise ratio can be reliably extracted from loud noise. The detection approach of weak signal based on SR indicates a promising prospect for mechanical fault diagnosis.

Abstract:A novel methodology has been presented to build a synthetic volumetric error model of a multi-axis NC machine tool of arbitrary configuration. The model includes original position errors and motion errors that account for geometric errors owing to manufacture, installation and motion control inaccuracy, thermal errors from thermal deformation of tool, machine and workpiece and mechanical loading errors etc. Thus it describes the error's facts of a machine tool and is useful to real-time compensation of the overall errors within the machine's working volume specially. In order to develop the new model, multi-axis kinematics and homogeneous transform matrices are utilized. Finally, based on the proposed modeling theory and method, the error model of a 3-axis NC vertical machine tool is introduced. In addition, its 36 error components are analyzed.

Abstract:The shifting drive bearing is a new special type bearing with supporting function as well as speed change function.The design of mechanism is novel and well-knit,with high efficiency and load-bearing capacity.By studying the internal structure and the driving principle of the shifting drive bearing, a group of systematic analysis is made. The theoretical relations of the tooth number of the internal-tooth ring,moving-tooth and drive radio,are provided,as well as the optimum seeking scheme of high efficiency and low wearing and tearing. The conclusion is drawn that the tooth number of moving-tooth should be larger than the internal-tooth ring : Z₂>Z₁. It is very important to direct the design of the moving-tooth drive structure which has push-rod, including the shifting drive bearing.

Abstract:The paper proposes a novel strategy for torque control, namely vector torque control (VTC), taking into consideration the field orient control (FOC) and direct torque control (DTC). It sets up a function to resolve the problem that no definite relation exists between output vector and control variations in the conventional DTC. Also it improves the stator flux model at low speed. In the end, experimental results show that the proposed strategy can improve the output characteristics of induction motor.

Abstract:Current sensor is an important element for on-line PD monitor of electric power equipment and its transfer characteristic has a direct influence on PD measurement. The paper shows the analysis of the transfer characteristic of current sensor and the result of theoretical analysis agrees with that of the experiment.

Abstract:A MCU system for industrial control is more sensitive to electromagnetic noise from power supply, and more likely to be influenced and degraded by internal and external disturbance than the average computer system. In the process of designing the power system, the buses and periphery interface, some measures can be taken to improve its EMC performance.

Abstract:According to the designing methods, computer animations can be divided into three kinds: frame-by-frame animation, keyframe animation and actor animation. Actor animations may meet the demand for real-time and interactivity. The model of actor is the key for actor animation. This paper mainly presents the modeling method of the actor in Net_Anim system developed by the author, which includes: the object-oriented model of the actor and the control scheme based on the model; the algorithms for synthesizing compound behaviors and some key problems to be considered; an example to demonstrate the compound actor with compound behaviors; the characteristics of Net_Anim and some problems to be solved in the future.

Abstract:The optimizing of the railway construction project organization variant, and the auxiliary designing system of picture format files are introduced. Relative calculation method used to optimize variant of the railway construction organization design with multi-level and multi-object decision making method is provided.

Abstract:The background and development of functional brain imaging are briefly reviewed. The optical imaging technologies of brain function are then introduced and classified. Several methods including voltage sensitive dyes imaging, optical imaging based on intrinsic signals, optical coherence tomography imaging, event-related optical signals imaging are summerized and compared, and the key factors of how to choose an optical imaging system recording fast brain activity are summed up. Based on the analysis and comparison, we suggest how to improve functional brain imaging technologies and point out possible directions for further research.

Abstract:This paper considers the problem of air target track identification based on the real-time tracker in surveillance system.The air target identity statistical model is established by analyzing the uncertainty of kinematic state and our and the enemy's attributes.Dempster-Shafer method is applied to develop the air target fusion identification.The results of simulation experiment show the applicability and effectiveness of the model and the algorithm.

Abstract:This thesis presents a system architecture of six-channel high speed data acquisition on PCI bus and implement it. This system, using a PC as the control unit, can be used to get data from three different kinds of radar, and implement data acquisition through six channels, and store large amount of data. In order to realize high speed and large amount acquisition, we use S5933 as PCI interface, using the high transfer speed of the PCI bus,satisfying the required data transfer rate between the control unit and the acquisition unit. At the same time we use dual-port RAM to provide continuous acquisition；and use FPGA to implement the control circuits, simplify the circuit board design and improve the flexility of the design. In order to ensure the security and stablity of the whole system,we implement the software system under Windows NT operating system

Abstract:This paper discusses the design of complex coefficients FIR filters in the complex Chebyshev sense. One way to solve this problem is to first formulate the complex Chebyshev approximation problem into finite linear programming through discretization, and then simplex method follows. But it has been thought that this method involves too much computation cost, converges slowly and it is applicable only for designing real coefficients FIR filters. Here a new algorithm is formed, which is a variant of the simplex method. It exhibits good convergence, low computation effort and can be used to design complex coefficients FIR filters. It proves equal to the algorithm formed from the dual of semi-infinite linear programming. An example is presented in the end.

Abstract:This paper presents two transform domain approaches to suppress the narrowband interference in a hybrid direct sequence frequency hopping spread spectrum system. Different algorithms used in determining and suppressing the interfered frequency bins are studied in detail，based on FFT frequency domain and MPWD time-frequency domain respectively. To avoid spectral leaking of the power, windowing can be performed prior to transformation. The simulated numerical results of the system bit error probability under different adaptive algorithms are provided.

Abstract:The SCFs of some noise, interfering and LPI radar signals are illustrated, the performance advantages of using SCF to detect LPI signals in noise or interference environments are analyzed. The SCF is also compared with Wigner-Ville distribution, dechirping and ambiguity, the equality among them is found. Moreover, several SCF algorithms are evaluated. It can be evidenced that the SCF is an efficient method of detection LPI signals, which has the good performance of resistance against the interference and the capability of realizing real time detection.

Abstract:Kinds of synthetic aperture radar (SAR) image filter methods are studied first, their faults being pointed out. Then a kind of SAR image filter method based on annealing and iterated filter is proposed, which describes image local property by correlated neighbourhood model. At first, a series of templates reflecting direction informatio are established and every template is present for a kind of neighbour structure. Then on the basis of SAR image statistical property, the MAP estimate of the real intensity under observation image values for every structure is got by Bayes formulation. Simulated annealing algorithm is used to get proper structure from the candidate structure according their probability, the estimate value corresponding to this structure is the estimate of the underlying cross-section. Simulated annealing algorithm makes sure that the best global result can be obtained when the temperature is reduced to zero.

Abstract:A 2-D Type-Discriminated Geometric Theory of Diffraction based (TD-GTD) model that discriminates between the localized and distributed scattering centers of the radar target is presented. This scattering model provides a more physical-relevant and richer description of high frequency complex scattering behavior compared with either point scattering models or prony models. To estimate the TD-GTD model parameters, Maximum Likelihood Estimation (MLE) algorithm is developed. An effective method of parameter initialization is proposed. Since estimating parameters of all scattering centers at the same time is the cause of high computational cost and complexity, RELAX technique is introduced into MLE algorithms to get around that difficulty. The efficiency and feasibility of the method is confirmed by the test based on the measured data.

Abstract:The characteristics of microstrip lines supported by photonic bandgap (PBG) structures are studied. Defected ground planes have been adopted to build up novel microstrip lines. Numerical simulation based on FDTD method and experiments have been carried out。The cases of rectangular holes and a filter constructed by cascaded PBG lines have been studied. Frequency transmission curves are given, and the existence of a bandgap is proved.

Abstract:Space-time multiuser detection based on constrained minimum output energy and its adaptive implementation are studied. This is a blind method which can suppress the multiple access interferences and solve the near-far problem without any training sequences. Furthermore, performances of the multiuser CDMA antenna array receiver are analyzed and compared with the performances of the multiuser single-antenna receiver, the single-user array receiver and the single-user single-antenna receiver.