Abstract:In this paper, the time-dependent numerical method has been used to solve the three dimensional Navier-Stokes equation, the numerical procedure uses Roe's flux difference splitting technigue and TVD scheme or LED scheme for the convective terms and central differencing scheme for viscous terms. Numerical solution of hypersonic laminar flow over a blunt biconic with attack angle is obtained.The resolution of shock, computational accuracy of viscous boundary layer and the efficiency of three schemes: Osher-Chakraverthy's TVD scheme, Harten's TVD scheme and Jameson's LED scheme, are investigated and compared by the numerical calculation of three dimensional hypersonic viscous flow.

Abstract:Being different from classic dimension analysis method and dimensionless method of flow's governing equations and its certain resolving conditions, this paper presents a new method to analyze flow's similitude law, scilicet decomposing complicated flow process to some sub-processes and analyzing characteristic quantity which represents sub-process' essence nature. According to this new method this paper presents law of similitude in non-equilibrium thermo-chemistry hypersonic flows, which is consistent with the law of similitude obtained by classic method in reference.

Abstract:The complex three dimensional flow field in liquid rocket engine is simulated with the method of predictive and corrective MacCormack scheme, and the parallel computation is carried out under the PVM circumstance which is made up of network of microcomputer. The results show that parallel and distributed method can play an important role on the numerical simulation in liquid rocket engine.

Abstract:Four types of GH₂/LO₂/RP-1 tripropellant injectors are employed to present the mixing characteristics test in this paper. The effects of the internal injector's recess on the mixing characteristics of the swirl coaxial injector with separate fuel injection are studied. The mixing characteristics of each injector are compared with those of the others in the same tripropellant operating condition. The effects of the injectors' configuration on the mixing characteristics are analyzed. The mixing characteristics tests of the single injector and three injectors are presented. The tests results show that the span of the mass flux distribution of the shear coaxial injector is smaller than that of the swirl coaxial injector in the same tripropellant operating condition. The conclusions reached in this paper provide a reference for the optimization design of the tripropellant injectors and the gas/liquid coaxial injectors.

Abstract:First, a new method of consistent testing in prior data and testing data is discussed. Considering credibility, we study Bayesian inference and Bayesian of maximum distance. Finally, the example is given.

Abstract:A numerical distributed transfer function method (NDTFM) is introduced for the analysis of state space equations of distributed parameter systems with variable coefficients. The method is the extension of DTFM (distributed transfer function method), and it is easy to use for various physical-mathematical problems with variable parameters. Wedge beam is analyzed using this method, and a general element is derived to raise numerical efficiency. Numerical results show that this method is efficient and easy to use.

Abstract:Electrorheological (ER) materials experience real-time and reversible changes in rheological and mechanical properties when subjected to electrical fields, which draw much attention to the use of ER materials in adaptive structures recently. ER sandwich beam is composed of two elastic layers and sandwiched ER layer. By controlling the pre-yield rheological and mechanical properties of ER materials, the dynamical response of the composed beam is then controlled. In this paper, ER sandwich beam simply supported at two ends is moded. The dynamical response of ER sandwich beam and the optimal electrical fields corresponding to different frequency are analyzed.

Abstract:The conjugative poly(2-methoxy-5-butoxy) phenylene vinylene is synthesized by using 4-methoxyphenol, 1-bromobutane and polyformadehyde as raw materials. The structure of intermediates and polymer is measured by IR and ¹HNMR. The V-I curve of polymer is also measured.

Abstract:The natural space radiation environment and the basic mechanisms of radiation effects are two most important issues relating to the research of radiation hardening techonology of spacecrafts. In this paper, some of the general properties of natural space radiation environment are summerized, the basic mechanisms of radiation effects are anylized briefly, and the emphasis of present research relating to the radiation hardening techonology of spacecrafts is pointed out.

Abstract:In this paper nonlinear wavelet approach to the recovery of signal from noisy data proposed by D.L.Donoho is described. and a new improved algorithm is provided aiming at the key problem of the approach, threshold design. The practical computing examples show that this new algorithm is very efficient, especially when signal noise ratio is lower, This algorithm is evidently better than that often used now.

Abstract:The new generation airborne early warning phased array radars will widely adopt flexible multiple-beam so that they will perform multiple functions. This paper presents a new practical STAP approach, which uses multiple-beam architecture and multiple time-delay taps. Moreover, the performance of this approach has been analyzed in detail by comparing with that of recent typical space-time adaptive processing (STAP) approaches. Theoretical analysis and computer simulation show that this method has the low degrees of system, good performance of detecting slow target, strong robustness to error.

Abstract:This paper is a continuation of three papers that were published in《Chinese Journal of Acoustics》in Chinese version and English version. It discusses three kinds of methods for combining the information of speech features that were presented in detail in the previous three papers in accordance with the theory of probability. The result shows the three methods improve the performance in speech recognition system. That is the same with the experiment result.

Abstract:Based on scale space theory, two methods for muti-thresholding are put forth in this paper. One of them consists of three main steps: first, the scale space representations are derived from finer level to coarser level; then, the locations of structures are corrected from coarser level to finer level; finally, the thresholds are derived from the lifetime of structures. The other method finds the structures at a coarser scale, and then focus on finest scale step by step to derive the thresholds. Experiments show that new ways are effective and robust.

Abstract:A high speed data recording system based on RAID is presented in this paper, which performs high speed mass storage data recording off-line the computer. It is proved that the sustained transfer rate is over 70MB/s and the storage is 184GB at the most.

Abstract:ESPRIT algorithm is a fast direction finding method with high resolution, but it is a 1-D method and can't be generalized to 2-D directly. This paper, based on a special array geometry, proposes a new 2-D direction finding method-2-D Virtual ESPRIT algorithm, whose low computation cost is comparable with to that of 1-D ESPRIT algorithm.

Abstract:In the receiving system of Ultra-Wide Band (UWB) coherent receiver, the amplitude and phase unbalances and DC offsets of in-phase and quadrature channels might affect the performance of the system. In this paper, the affection of imbalances and DC offsets of I/Q demodulators to signal processing are analyzed. One method of calibrating of amplitude and phase imbalances is introduced and the result of computer simulation is given.

Abstract:Real-time operating system is one important component of complex real-time system. The operating system itself must be predictable. This paper first analyzes and describes the real-time functions of DEC UNIX 4.0. And then we secondly developed a effective test approach of real-time operation system performance. Finally we give the test process and results of DEC UNIX4.0B running on DEC Alpha series computers.

Abstract:It is necessary to understand the mode of I/O mode before designing a parallel file system (PFS). The structure, interface and algorithm of cache/prefetch is closely related to application. Now, most analyses are based on static I/O model, but the dynamic mode is much more important to PFS. This paper analyses the dynamic I/O mode of parallel scientific application, and summarizes the characteristics of I/O size, interval, sequence and so on. The conclusion of what should be considered when designing a PFS is finally drawn.

Abstract:Base on a case of collocating computing system design, this paper discusses the principles of system partitioning, communication mechanism, and high-performance parallel computing of the distributed multi-computers system.

Abstract:This article introduces the active service, discusses the system framework based on CORBA Event Service. And it presents the system's application to telecommunication.

Abstract:First, the localization of QRS complex in each lead is detected by using hypothesis testing on electrocardiograph(ECG) signal's wavelet transform, and the probability of false alarm and the probability of miss are also computed. Then, the peak comparison fusion and decision weightiness fusion are applied to 12 leads' decision to obtain the precision lccation of each QRS complex. The experiments show that we are able to detect the QRS complex correctly for various pathological ECGs by this method, and the correct detection rate of QRS complex can be above 99.95%.

Abstract:Considering the relationship between the measures of terrain correlation algorithms and the 2-D self-correlation coefficient of terrain, this paper proposes an improved Johnson method-to analyze the statistical properties of measures of matching algorithms on correlated terrain. First, based on the issue of Johnson method, we modify the independence assumption of consecutive elements in reference data and develop distribution functions of measures of MSD. Then, the suitability of Johnson method and our method are discussed, and the shortcomings of the former are pointed out. Finally, an application of our method to terrain correlation suitabitity, to estimate the false-fix probability in correlated non-matching positions is presented.

Abstract:The significant problem of mechantronics equipment built-in test (MEBIT) is its high false alarm rate. One of the important causes is its sensor channel's fault of BIT system. The method of neural network is adopted for the sensor channel fault diagnosis. The fault mechanism and types of sensor channels of MEBIT in a large ship power engine and the fault samples are obtained. After the training of neural network, the actual system's faults are diagnosed and identified. The experimental results show that the neural network can diagnose the faults and identify their types. The method is compact, effective and of practical value.

Abstract:An application and the controling way of serial communication between programmable logic controller and motor speed controller are introduced。The system structure and the designing method of application software are also described. The controling way of motor speed controller by PLC serial communication is given。

Abstract:In this paper, when two robots rigidly grasp an object to contact the gurround, using the simplified model of the two symmetric coordinated robots, we analyze the effect on the stability of the internal force and external force symmetric control system due to the unmodeled factors: (1) the equivalent motor dynamic of robot, (2) the stiffness of the object grasped by two robots, (3) the dynamic of the object, (4) the sampling control delay of the computer control, (5) the dissymmetry of two robots. Then the results of the simulations are given, which accord with the experimental results.

Abstract:In this paper, we study the construction of dispersion detecting method of the falling points. when the stopping time is given, a sequential truncated detecting algorithm is designed, and then, the upper bounds of the probability of errors of two kinds are given. The using of prior information and the expression of prior probability of null bypothesis are also discussed.

Abstract:In this paper, the principle of determining attitude of high dynamic carrier with GPS carrier-wave phase measurement, and its pivotal correlation technology has been deeply studied. In order to achieve the aim of synchronism, a method of realizing the speedy determining attitude with space geometry restrain has been presented. Moreover, we carry out a large number of simulation calculation and precision analyse.

Abstract:This article presents an approach to study the modeling of multi-agent systems (MASs) by integrating organization theory. The paper discusses the modeling method of analyzing and designing the MASs, from macro to micro, at different abstract layers of the whole organization, agent, and concurrent action, and describes in detail three abstract models about the System organization model, agent conceptual model, and distributed cooperative solving model for designing the MASs.

Abstract:The mathematical description of chain-wheel drives with two fixed non-cricular wheels, a transmission chain of constant length and g give non-costant velocity-ratio leads to a system of nonlinear functional equations. It seems impossible to solve this equations, but we can construct a set of tangents of thesse wheels by kinematic methods. The desired curve can be approximated by constructing spline curve. This paper considers piecewise raional cubic Bezier curve which has all these tangents as tangents, the curve is G²-continuous and shape-preserving.

Abstract:Using a conclusion of time-constant-attenuation after loss-of-excitaion only decided by generator parameters and failure-modes, the paper according to the classify of loss-of-excitation faults, adopts a three-lay feed-forward neural network to obtain“T_q”,Which makes microcomputer-based Loss-of-Excitation protection in the twinking of fault happening failure-mode-recognition and loss-degree-prediction. Figure simulating, trend imitate testing and action moving proved that the method raised is correct.