The discrete wavelet transform decomposes a discrete time signal into an approximation sequence and a detail sequence at each level of resolution. Compactly supported orthonormal wavelets correspond to perfect reconstruction (PR) quadrature mirror filter (QMF) banks. This paper deals with the problem of choosing orthogonal wavelet (scaling) filters for best signal approximation at some scales. By using a kind of parametrization method, the constrained optimization can be converted into an unconstrained one.Some simulations are shown here.

A new three dimensional imaging method for electroencephalogram (EEG) is suggested. It consists of the solution of an inward spherical harmonic continuation. After introducing the principle of the new method, numerical simulation is made and the feasibility of the method is confirmed by the simulation results.

The synthesis of resonant frequencies of microstrip antenna is investigated using the extreme synthesis method. The theoretical and experimental results are in good agreement. These satisfactory results show that the method is feasible for developing the synthesis of resonant characteristics of microstrip antenna and for promoting the applications of microstrip antenna in engineering.

Within the framework of exact scattering theory and under the wave zone condition, the image reconstruction is studied. It is demonstrated that there is only a two dimensional Fourier dual space in the problem of scattering-inverse scattering. An eyelike principle for the imaging at monofrequency, monoincidence and small imaging angle is proposed and an interesting complementary relation between the imaging angle and operation wave length for the inverse scattering is revealed. Theoretical results are verified by computer simulations. An eplanation on interpreting human vision with wave theory is attempted.

The fields in transition and caustic region of dielectric coated objects are obtained by geometric theory of diffraction. In transition region, direct computation is accomplished by modifying the residue series solution. The equivalent currents are extended to deal with the creeping wave in caustic region. The comparison of computation resuts with the eigenfunction solution shows that the presented methods are efficient.

DQDB metropolitan area network is a promising solution for the evolution from current networks to B-ISDN. The performance of DQDB MAN for LANs interconnection is analyzed. The effects of message length, traffic load of upstream and downstream nodes and the parameters of bandwidth balancing mechanism and network counters on the sojourn time of message in the buffer are investigated, which present a valuable reference for the implementation of DQDB MAN.

Supposing C is an irreducible algebraic curve of genus g, C*(D, G) is an algebraic geometric code of designed minimum distance d* = degG- 2g+2. This paper, first, proves that the given algorithm is reasonable theoretically, then gives a decoding algorithm based on Fundamental Iterative Algorithm (FIA), which is a modification of the algorithm proposed by G. L. Feng, et al. (1993) and can correct any received code of (d* -1)/2 or less errors with complexity only one half of that of the algorithm proposed by G.L.Feng, et al. The procedure can be implemented easily by hardware or software.

This paper presents the necessary and sufficient conditions for the no-nsingularity of feedback shift registers of degree at most three on finite fields GF(q).

A method to deposit hematite (Fe₂O₃) thin films by plasma-enhanced chemical vapor deposition (PECVD) is introduced. The structure and particle-size of Fe₂O₅ thin film are analysed by X-ray diffraction and SEM, respectively. The gas sensitive properties of thin film to LPG, coal gas, hydrogen and ethanol are studied. The results show that films prepared in this way are highly sensitive to ethanol. However, it is not so sensitive to LPG, coal gas or hydrogen. Therefore the film is proved to have high selectivity.

Starting from the mathematical expressions of storage function, this paper investigates various structures of tri-latches based on modular algebra and lattice algebra systemtically. At the request to input the signal to be stored into these tri-latches, the paper deduces some design techniques to interrupt the feedback rings with AND gate, OR gate and 1 of-2 multiplexer respectively. By the above techniques, ternary basic flip-flops can be derived further.

The models of the basic gates and typical flip-flops for Petri net are constructed by using a kind of extended Petri net with inhibitor arc. Then the syncronous sequential circuit are described. The enabled matrixes, the state equations and the relation between the next state of flip-flop and the enabled transition are given. Based on these, the analysis method of Petri net for synchronous sequential circuits is discussed. It is proved that the theory is effective by practical examples.

Let Q(n,d) denote the largest number of cod-words in any binary equidistant code of length n and Hamming distance d between code words, this paper determines some exact values of Q(n,d), and presents several properties of optimal equidistant codes.

The fundamental principles and techniques of radioastronomical method by using the sun in the measurement of antenna three-dimensional pattern are described. And a total radiometer is used for measurement system. Collection and calculation of the data are performed,by the computer. The aperture and operating wavelength of the measured antenna are respectively 20m and 17.8cm. Measured level is estimated to be -41dB, and measured error is about ±0.6dB.

Improvement on moving target signal processing in the noncoherent radar systems is important for designing radars. This paper deals with the effects of the radar instabilities and method for decreasing the instabilities. Theoretical calcuation agrees with experimental measurement satisfactorily. The results can meet the demand of engineering.

This paper presents a so called equivalent transmission line method for the analysis of multilayer dielectric waveguide involving nonlinear dielectric. By introducing the equivalent transmission line model of nonlinear dielectric and linear dielectric, the electromagnetic field problem about the nonlinear dielectric waveguide can be equivalent to a circuit problem. The eigen-equation governing the nonlinear dielectric waveguide can be obtained by using the transversal resonance technique. Finally, the multilayer dielectric waveguides involving saturable or non-saturable nonlinear dielectric are simulated, and the relations between the propagating power of TE mode and the normalized wavenumber are given. The results obtained are in good agreement with that in the references.

A dry sculpture experiment for YBa₂Cu₃O_7-δ superconducting film using scanning electron beam is presented. The effects of beam technological parameters on sculpture result are tested. The modification mechanism for superconducting films is discussed prelimiarily.

The architecture and technical characteristics of the master control system of airborne SAR real-time digital imaging processor (RDIP) are studied. Master Control system (MCS) is designed under the real-time operating system(OS). The real-time (OS) is built around the industry standard real-time executive known as the pSOS + . The pSOS+ supports real-time system by using basic multitask mechanisms, and the real-time OS is designed to perform funtions or tasks in a nonsequential manner. The mechanisms of pSOOS+- tasks scheduling, tasks communication and syuch- ronization in the RDIP MCS are discussed. Furthermore the questions about data transporting among tasks and man-machine dialogue also discussed.

Oversampling sigma-delta conversion technology is widely used for high-resolution A/D and D/A conversion in the audio frequency band, and also gives interesting advantages in efficient signal processing. This paper reviews the development and basic methods of the technology. The prospects of application and the ways of development are also discussed.