Showing papers by "Xidian University published in 1994"
TL;DR: It is shown that McEliece's and Niederreiter's public-key cryptosystems are equivalent when set up for corresponding choices of parameters and a security analysis for the two systems is presented.
Abstract: It is shown that McEliece's and Niederreiter's public-key cryptosystems are equivalent when set up for corresponding choices of parameters. A security analysis for the two systems based on this equivalence observation, is presented. >
172 citations
TL;DR: In this article, the reflection coefficients of an inhomogeneous lossy medium illuminated by both TE and TM-polarized electromagnetic plane waves are derived using a microwave networking technique, which can be approximately solved by a nonlinear renormalization method.
Abstract: Nonlinear differential equations for the reflection coefficients of an inhomogeneous lossy medium illuminated by both TE-polarized and TM-polarized electromagnetic plane waves are derived using a microwave networking technique, which can be approximately solved by a nonlinear renormalization method. Considering the equivalent microwave network of the permittivity profile discontinuity at the interface of free space with the medium, two novel inverse scattering solutions for the permittivity profile and the conductivity profile are further investigated in closed forms. Closed-form and numerical reconstruction examples show the availability of this scheme. >
40 citations
TL;DR: In this article, the generalized Lorenz-Mie theory (GLMT) is applied to the analysis of an existing dual-cylindrical wave system (DCW) measurement system.
Abstract: The use of a laser sheet (or elliptical Gaussian beam) in measurement techniques is of growing interest. Some of these techniques take advantage of the wavefront curvature of such beams as in a dual-cylindrical wave system (DCW). Nevertheless, up to now, the analysis of the properties of the light scattered by spherical particles from the beam has been carried out largely by using geometrical optics or classical Lorenz-Mie theory. The generalized Lorenz-Mie theory (GLMT) is applied to the analysis of an existing DCW measurement system. Differences between the results predicted by classical approaches and by GLMT are emphasized
33 citations
TL;DR: In this article, a method to deposit haematite (Fe 2 O 3 ) thin films by plasma-enhanced chemical vapour deposition (PECVD) is introduced and the sensitivity of the PECVD Fe 2 o 3 thin films to liquified petroleum (LP) gas, coal gas, hydrogen (H 2 ) and ethanol (C 2 H 5 OH) is studied.
30 citations
TL;DR: A large class of electromagnetic beams (including Gaussian beams and laser sheets) complies with symmetry relations that are then mathematically expressed in the framework of the generalized Lorenz-Mie theory as discussed by the authors.
Abstract: A large class of electromagnetic beams (including Gaussian beams and laser sheets) complies with symmetry relations that are then mathematically expressed in the framework of the generalized Lorenz–Mie theory (GLMT). In particular, by using such symmetry relations in evaluating the beam-shape coefficients, one can efficiently speed up GLMT computations.
24 citations
TL;DR: In this paper, an integrated optimization design of mechanics and electronics for the high performance reflector antenna is considered and an efficient synthetic method is developed, where a general mathematical expression of the phase centre for reflector antennas feeds is given.
24 citations
TL;DR: Computer simulations indicate that simulated annealing is useful in providing good upper bounds to the minimum distance of general linear block codes.
Abstract: Simulated annealing is a Monte Carlo method for obtaining approximate solutions to combinatorial optimization problems It is used to compute the minimum distance of linear block codes in this paper Computer simulations indicate that simulated annealing is useful in providing good upper bounds to the minimum distance of general linear block codes
16 citations
TL;DR: It is proven in this paper that the (5, 2, 2) code, (6,2, 3) code and (8, 2-4) code are the only proper error-detecting codes in the (n, 2), m) nonlinear constant weight codes for n/spl ges/5, in the sense that their UEP is increased monotonically with the channel error rate p.
Abstract: The undetected error probability (UEP) of binary (n, 2/spl delta/, m) nonlinear constant weight codes over the binary symmetric channel (BSC) is investigated, where n is the blocklength, m is the weight of codeword and 2/spl delta/ is the minimum distance of the codes. The distance distribution of the (n, 2, m) nonlinear constant weight codes is evaluated. It is proven in this paper that the (5, 2, 2) code, (5, 2, 3) code, (6, 2, 3) code, (7, 2, 4) code, (7, 2, 3) code and (8, 2, 4) code are the only proper error-detecting codes in the (n, 2, m) nonlinear constant weight codes for n/spl ges/5, in the sense that their UEP is increased monotonically with the channel error rate p, of course all these proper codes are m-out-of-n codes. Furthermore, it is conjectured that except for the cases of n/spl les/4/spl delta/, there are no proper error-detecting binary (n, 2/spl delta/, m) nonlinear constant weight codes, for n>8 and /spl deltaspl ges/1. >
16 citations
TL;DR: In this paper, it was shown that a dominant mode of trivial cutoff frequency may be supported by a parallel-plate chirowaveguide, which exhibits the characteristics of a TEM mode when the chirality of the medium vanishes or the operating frequency is very low.
Abstract: It has been reported that the lowest cutoff frequency of the modes in a parallel-plate chirowaveguide is not zero. In this paper, we show that a dominant mode of trivial cutoff frequency may be supported by such a chirowaveguide. The mode exhibits the characteristics of a TEM mode when the chirality of the medium vanishes or the operating frequency is very low. An analogous mode also exists in a bianisotropic chiral coaxial line, i.e., the structure formed by more than one conductor. >
14 citations
TL;DR: In this article, the authors indicate that the conjecture of Beth and Dong (Proc. Crypto 1992) is wrong and present some permutations with high nonlinear order and good nonlinearity.
Abstract: In the Letter, the authors indicate that the conjecture of Beth and Dong (Proc. Crypto 1992) is wrong. Some permutations with high nonlinear order and good nonlinearity are also presented. >
12 citations
TL;DR: An alternative which combines some of the best features of the k-nn and neural network classifier is described by the authors, called a packed hyper-ellipsoid classifier.
Abstract: Pattern classification is frequently performed using the k-nn algorithm or a neural network. The choice of parameters for the former is often difficult and the amount of data which has to be stored in the classifier can be high. Neural network classifiers can overcome some of these problems but learning is often unreliable and slow. An alternative which combines some of the best features of the k-nn and neural network classifier is described by the authors. The classifier is called a packed hyper-ellipsoid classifier. >
TL;DR: In this article, the reliability constraints, namely displacement and stress, are transformed into constraints of conventional forms according to the characteristics of invariance in a linear elastic structures to the normal loads, and the problem of reliabliltiy optimization is solved by the mixed method.
TL;DR: This new fuzzy-decision-based invariant pattern recognition method for object recognition is presented and is shown to have all the essential invariant properties and robustness against noise and uncertainty.
TL;DR: In this article, the elastic engineering structure response to wind load is analyzed by means of the random vibration and finite element method, with which both the static and dynamic response of structures can be obtained simultaneously.
01 Feb 1994
TL;DR: In this article, a method for designing Chebyshev-type complex FIR filter and DBFs with linear-phase characteristics is proposed, where a zero exchange algorithm and related procedures are used to iteratively find the best approximation to a variety of desired frequency responses.
Abstract: Based on the theory of optimal polynomial approximation, the authors present a complex alternation theorem which shows the existence of Chebyshev complex FIR filters. According to the theorem, a method for designing Chebyshev-type complex FIR filter and DBFs with linear-phase characteristics is proposed. A zero exchange algorithm and the related procedures are used to iteratively find the best approximation to a variety of desired frequency responses and directivity patterns. Several examples are included to show the efficacy of the designs of FIR filters with multistop-/multipassband responses, DBFs with pencil beams and local low sidelobes, and pattern synthesis with a shaped mainlobe.
TL;DR: In this paper, the phase properties of initially coherent light interacting with two identical two-level atoms using the Hermitian phase operator of Pegg and Barnett were studied, and it was shown that, in a certain initial state of the atoms, the field would preserve its order in phase, even for a long interaction time with the two atoms.
TL;DR: In this paper, a novel matrix perturbation technique for the matrix equation [A][u]=[b] is presented, which is especially suitable for pathological cases in which the dielectric characteristics or the shape of the biological body vary due to disease.
Abstract: A novel matrix perturbation technique for the matrix equation [A][u]=[b] is presented. One of its applications, the computation of internal fields in a three-dimensional arbitrarily shaped heterogeneous biological body illuminated by a plane wave, is further investigated by using the technique. If one regards a normal biological body as the primary model and stores its computation results, when small perturbations in the dielectric characteristics or the shape of the body occur, the internal fields in the perturbed biological body can be rapidly computed using the stored results. Compared with the usual moment methods, the new technique has an equivalent precision, yet takes only 1/70 the execution time. This technique is especially suitable for pathological cases in which the dielectric characteristics or the shape of the biological body vary due to disease. >
TL;DR: A nonlinear differential equation for the reflection coefficient of a pure conducting medium is derived by using a microwave networking technique, which can be approximately solved by a nonlinear renormalization method.
Abstract: A nonlinear differential equation for the reflection coefficient of a pure conducting medium is derived by using a microwave networking technique, which can be approximately solved by a nonlinear renormalization method. From the renormalization solution of the reflection coefficient, a novel inverse scattering formula to the conductivity profile is further investigated in the closed form. Reconstruction examples show that the novel formula is more accurate than the results in D.B. Ge et al. (1991) and T.J. Cui et al. (1992). >
TL;DR: In this article, a triangulation of continuous and arbitrary refinement of grid sizes is proposed for simplicial homotopy algorithms to compute zero points on a polytopeP. The proposed algorithm generates a piecewise linear path inP × [1, ∞) from any chosen interior pointx0 ofP on level {1} to a solution of the underlying problem.
Abstract: In this paper a triangulation of continuous and arbitrary refinement of grid sizes is proposed for simplicial homotopy algorithms to compute zero points on a polytopeP. The proposed algorithm generates a piecewise linear path inP × [1, ∞) from any chosen interior pointx
0 ofP on level {1} to a solution of the underlying problem. The path is followed by making linear programming pivot steps in a linear system and replacement steps in the triangulation. The starting pointx
0 is left in a direction to one vertex ofP. The direction in whichx
0 leaves depends on the function value atx
0 and the polytopeP. Moreover, we also give a new equivalent form of the Brouwer fixed point theorem on polytopes. This form has many important applications in mathematical programming and the theory of differential equations.
TL;DR: It is proved that there exists no graph with the property that every pair of vertices is connected by a unique path of length k, k > 2, for k ⩾ 12.
TL;DR: Based on the Hulthen-Kohn variational method for calculating the reflection coefficient, a closed-form approximation formulation is used in this Letter for inverting the potential profile as discussed by the authors.
Abstract: The potential profile of the one-dimensional Schrodinger equation may be inverted from the reflection coefficient. For example, the famous Gel'fand-Levitan equation shows their relation. But, in the general case, GL equation may hardly be solved exactly. Based on the Hulthen-Kohn variational method for calculating the reflection coefficient, a closed-form approximation formulation is used in this Letter for inverting the potential profile. Inversion examples show that this formulation works better than the famous modified Born approximation. © 1994 John Wiley & Sons, Inc.
TL;DR: The transmission and reflection properties of Faraday rotators are investigated by use of the boundaryvalue approach and Transmission and reflection coefficient matrices are derived from boundary conditions and transmission and reflect functions.
Abstract: The transmission and reflection properties of Faraday rotators are investigated by use of the boundary-value approach. Transmission and reflection coefficient matrices are derived from boundary conditions and transmission and reflection functions. The performances of extinction ratio and insertion and return losses of Faraday rotators are calculated for yttrium iron garnet, bismuth-substituted iron garnet, and BiCaInVIG (a non-rare-earth iron garnet) Faraday rotators.
TL;DR: In this article, the authors investigated the model of a continuous time Markov decision decision process (CTMDP) in a semi Markov environment with discounted criterion and proved the optimality equation and the existence of ∊, ∊−optimal policies.
Abstract: This Paper investigates the model of a continuous time Markov decision decision Process (CTMDP for short) in a semi Markov environment with discounted criterion. The model describe a system Which behaves like a CTMDP except that the system is influenced by its environment Which is described by a semi-Markov Process Following each change of the environment states there occur three things:1) an instantancous state (of the system ) transition:2) an instantaneous reward:3) the Paramenters of the CTMDP varify. After presenting the precise formulation of the model, we prove the optimality equation and the existence of ∊,-optimal policies. then approximating results are obtained when the underlying distribution functions (d.f.s) of the semi-Markov environment are approximated, and the special case of phase type environment is treated.
TL;DR: A fast separable approach based on a cross array is presented, which has coarsegrained parallelism and in order to compensate for the performance degradation due to separable processing, two postprocessing schemes are also proposed.
Abstract: A fast separable approach based on a cross array is presented, which has coarsegrained parallelism. Its computational load is far less than that of the two-dimensional (2-D) direct processing method and other existing separable approaches. In order to compensate for the performance degradation due to separable processing, two postprocessing schemes are also proposed. Some computer simulation results are provided for illustration in the end.
19 Aug 1994
TL;DR: In this paper, the dielectric constant of sand-powders sampled from desert area have been measured at W band by means of waveguide method and the algorithm about equivalent dielectrics constant of analogical sandstorm have been discussed.
Abstract: Dielectric constant of sand-powders sampled from desert area have been measured at W band by means of waveguide method. The algorithm about equivalent dielectric constant of analogical sandstorm have been discussed. It is very useful to test the sand-powders of the desert sample at laboratory, to make analogical analysis of sandstorm and to research the effects of sandstorm in desert area upon electric wave propagations.© (1994) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.
10 May 1994
TL;DR: In this article, the phase difference variation characteristics between frequency signals can be recognized essentially based on the frequency relationship between two signals and the influence of 'phase coincidences' distribution between signals upon the measurement.
Abstract: On the basis of phase difference variation characteristics between frequency signals, regularities of periodic signals can be recognized essentially. This paper describes the characteristics with which the greatest common factor frequency, the least common multiple period and quantized minimum variation of phase difference vary according to the frequency relationship between two signals. It analyses the influence of 'phase coincidences' distribution between signals upon the measurement. According to the characteristics, using the phase coincidence detection method highly accurate measurements of frequency and other periodic signal parameters can be accomplished. A much higher accuracy can be obtained for some special frequency signals. By means of the principle, a lot of new instruments have been built. They show more than 3 to 5 orders accuracy over that of ordinary instruments. >
TL;DR: A fast fuzzy c-means (FCM) clustering algorithm with two layers, which is a mergence of hard clustering and fuzzy clustering, and the application of the proposed algorithm to image segmentation based on the two dimensional histogram is provided.
Abstract: This paper presents a fast fuzzy c-means (FCM) clustering algorithm with two layers, which is a mergence of hard clustering and fuzzy clustering. The result of hard clustering is used to initialize the c cluster centers in fuzzy clustering, and then the number of iteration steps is reduced. The application of the proposed algorithm to image segmentation based on the two dimensional histogram is provided to show its computational efficience.
25 May 1994
TL;DR: In this article, a transversely excited atmospheric (TEA) CO2 laser with gas internal coaxial circulation scheme is presented, which is able to operate at 33Hz with more than 106 arcing-free discharge.
Abstract: A transversely excited atmospheric (TEA) CO2 laser with gas internal coaxial circulation scheme is presented. To ensure stable discharge the free potential plate UV corona preionization technique is employed. The gas flow velocity reaches 15 meters per second, when the motor rotates at 8000 turns per minute. The TEA CO2 laser is able to operate at 33Hz with more than 106 arcing-free discharge. The minimum clear ratio is found smaller than theoretical limit (root)3.© (1994) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.
13 Apr 1994
TL;DR: The experiments show that RSNN is easier to train and gives higher performance than RNN.
Abstract: Recurrent neural networks (RNNs) can be used to handle sequential patterns and have been used for speech recognition. To overcome the shortcomings of RNN, recurrent sub neural networks (RSNNs) are used, where an RSNN is built independently for each class. The training algorithm of the RSNN is based on the backpropagation algorithm. Speaker dependent connected Chinese digit-speech recognition experiments were carried out. Some factors influencing the performance of RSNNs have been studied. The experiments show that RSNN is easier to train and gives higher performance than RNN. >
TL;DR: In this paper, the Volterra functional method is used for the electromagnetic inverse problem and a general analytical procedure and symbolic computer code implementation are successfully constructed that provides an alternative way for the inverse problem.
Abstract: The Volterra functional method is used for the electromagnetic inverse problem. A general analytical procedure and symbolic computer code implementation are successfully constructed that provides an alternative way for the inverse problem. The conductivity profiles, as an example, are reconstructed by the method. The results show that using only three terms of an expansion gives an obvious improvement when compared with former approximations.