Showing papers by "Southeast University published in 1993"
TL;DR: A three-dimensional edge operator for detecting anatomical structures in medical imaging that uses the spatial moments of the gray-level surface, and operates in three dimensions with any window size is presented.
Abstract: A three-dimensional edge operator for detecting anatomical structures in medical imaging is presented. It uses the spatial moments of the gray-level surface, and operates in three dimensions with any window size. It allows the location and the contrast surface, as well as the surface orientation, to be estimated. The computation of the discrete version is reported. Bias and errors due to the spatial sampling and noise are analyzed at both a theoretical and experimental level. The moment-based operator is compared with other well-known edge operators using simple shaped primitives for which the analytical solution is known. The 3-D rendering of real data is then provided by merging the operator in a ray-tracing framework. >
59 citations
TL;DR: Simulation results indicate that the present approach to determine the dynamically optimal values of learning rate and momentum factor can provide a remarkable improvement in convergence performance.
Abstract: Learning rate and momentum factor are two arbitrary parameters that have to be carefully chosen in the conventional backpropagation (BP) learning algorithm. Based on a linear expansion of the actual outputs of the BP network with respect to the two parameters, the Letter presents an efficient approach to determine the dynamically optimal values of these two parameters. Simulation results indicate that the present approach can provide a remarkable improvement in convergence performance.
49 citations
TL;DR: In this paper, the authors define coherence relative to an arbitrary torsion theory and characterize it in terms of preenvelopes of modules, and obtain some known results as corollaries.
Abstract: We define coherence relative to an arbitrary torsion theory and characterize it in terms of preenvelopes of modules. In particular, some known results are obtained as corollaries.
48 citations
TL;DR: A new method for the three-dimensional tracking and the quantification of blood vessels from magnetic resonance angiography (MRA) based on 3-D geometrical moments, validated on simulated and real data.
Abstract: This paper describes a new method for the three-dimensional (3-D) tracking and the quantification of blood vessels from Magnetic Resonance Angiography (MRA). The approach is based on the 3D geometrical moments and consists of the following steps : (1) interactive selection of 3-D seed points ; (2) automatic tracking of the vessels ; (3) local computation of both diameter and orientation ; (4) rendering of the vessels. This detection and estimation scheme has been validated on simulated and real data.
44 citations
TL;DR: In this paper, a new type of hysteresis, termed temperature deviation (TD), is described and the physical mechanisms for both TOS and TD are analyzed in detail using thermodynamic nucleation.
41 citations
TL;DR: This paper presents a reasonable analytical model of fuzzy closed-loop systems, and then proposes a method to analyze the stability of control systems by the relational matrix of fuzzy systems.
31 citations
TL;DR: Split-polarity transformation (SPT) as discussed by the authors is incorporated into conventional linearly constrained minimum variance (LCMV) beamformers to decorrelate the desired signal from interference.
Abstract: Split-polarity transformation (SPT), which is incorporated into conventional linearly constrained minimum variance (LCMV) beamformers to decorrelate the desired signal from interference, is presented. The SPT processor does not distort the direction vectors associated with wave fronts impinging on the array, but it does reverse the phase of the signal coming from a specified direction. With the aid of SPT processing, the signal cancellation due to correlation between the desired signal and interference is almost eliminated. The design of a robust SPT processor for combating the effects of mismatch between idealized array model and actual scenario arising from causes such as sensor location, amplitude, and phase errors is discussed. A detailed performance study of the SPT-LCMV beamformer shows it to be robust against direction uncertainty in the assumed look direction. Numerical results are presented to demonstrate the effectiveness of the SPT-LCMV beamforming scheme is a coherent interference environment. >
26 citations
TL;DR: In this paper, the elastic body structure of the wrist force sensor was introduced, and the mechanically decoupled principle was analyzed in detail, which is different from the conventional mechanically coupled wrist force sensors.
Abstract: The novel six-degree-of-freedom (6 DOF) wrist force sensor described here is mechanically decoupled. This type of wrist force sensor is different from ordinary mechanically decoupled ones. It has a simple structure and small cross-sensitivity (or interference among dimensions). It is easy to process and calibrate, and low in cost. This paper introduces the elastic body structure of the wrist force sensor, and analyses the mechanically decoupled principle in detail.
24 citations
TL;DR: In this paper, a single water droplet impinging upon a hot solid surface has been investigated experimentally, and the instantaneous radius of the spreading droplet was measured by an electrical resistance probe.
24 citations
TL;DR: In this article, the authors investigated the properties of the states a + n b + m S 2 ( ξ )|00〉 (λ = r e i θ ), which represent the excitations on the two-mode squeezed vacuum.
19 citations
17 Oct 1993
TL;DR: In this paper, genetic algorithm is studied and introduced into the probabilistic causal diagnostic model to solve the multi-disorder simultaneously diagnostic problem with NP-complexity.
Abstract: Genetic algorithm (GA) is a novel global optimal algorithm based on Darwin's evolution thought. It emulates the rules of biological evolutionary process, such as reproduction, gene, mutation, and natural selection, etc. As a mathematic model of evolution, GA is of its special efficacy on the searching and optimizing problems which have large solution space. In this paper, GA is studied and introduced into the probabilistic causal diagnostic model to solve the multi-disorder simultaneously diagnostic problem with NP-complexity. In addition, the influences of the GA control parameters on its solving process are studied. >
TL;DR: An analytical treatment of the Camley-Barnas theory of the magnetoresistance (MR) in magnetic layered structures is presented and an exact and general expression for the MR is obtained.
Abstract: We present an analytical treatment of the Camley-Barnas theory of the magnetoresistance (MR) in magnetic layered structures and obtain an exact and general expression for the MR Particular attention is given to the multilayer effect for the enhancement of MR change It is proposed that the MR formula obtained from a single sandwich system can be used to calculate the MR effect of a multilayer structure provided an effective specularity factor for the reflection by the surfaces is introduced as a function of the number of bilayers The theoretical results are in good agreement with experimental data for the epitaxial (Fe/Cr) n /Fe multilayers
TL;DR: An identification approach to three-phase power system modeling and model reduction taking the power system network network as multi-input, multi-output (MIMO) process is presented in this article.
Abstract: An identification approach to three-phase power system modeling and model reduction taking the power system network as multi-input, multi-output (MIMO) process is presented. The model estimate can be obtained in discrete-time input-output form, discrete- or continuous-time state-space variable form, or frequency-domain impedance transfer function matrix form. An algorithm for determining the model structures of this MIMO process is described. The effect of measurement noise on the approach is also discussed. This approach has been applied to a sample system. Simulation results are presented. >
TL;DR: The truncated modal model and the aggregated mass model used in turbogenerator torsional oscillation analysis are presented in this article, which can be implemented into existing programs without any difficulty, while the fidelity can easily be adjusted by changing their orders.
Abstract: Two very simple, sufficiently accurate reduced-order shaft system models, the truncated modal model and the aggregated mass model, used in turbogenerator torsional oscillation analysis are presented. The first is developed by taking the exact duplicate of the transient behavior of the original as far as the low-order modes are concerned, while the second is established by fitting the low-order mode shapes of the original. They can be implemented into existing programs without any difficulty, while the fidelity can easily be adjusted by changing their orders. >
TL;DR: In this article, it was shown that if R is a commutative coherent ring, the weak global dimension of R equals the supremum of the flat (or FP-injective) dimensions of the simple R-modules.
Abstract: We prove that (a) if R is a commutative coherent ring, the weak global dimension of R equals the supremum of the flat (or (FP–)injective) dimensions of the simple R-modules; (b) if R is right semi-artinian, the weak (respectively, the right) global dimension of R equals the supremum of the flat (respectively, projective) dimensions of the simple right R-modules; (c) if R is right semi-artinian and right coherent, the weak global dimension of R equals the supremum of the FP-injective dimensions of the simple right R-modules.
TL;DR: In this paper, lead titanate fine powders derived from the metal alkoxide hydrolysis precipitate precursor treated under hydrothermal conditions have been obtained and three kinds of lead titanates with different structures have been formed and fine particles with different morphologies have been successfully obtained.
Abstract: This paper reports lead titanate fine powders derived from the metal alkoxide hydrolysis precipitate precursor treated under hydrothermal conditions. The influences of pH value, Pb/Ti mole ratio, reaction temperature and time on the hydrothermal synthesis of the phase transformation and particle morphology have been investigated. As a result, three kinds of lead titanates with different structures have been formed and fine particles with different morphologies have been successfully obtained.
TL;DR: In this article, angle-dependent X-ray photoelectron spectroscopic studies on the covalent binding of bifunctional reagents to silanized silicon wafer surface are reported.
01 Jan 1993
TL;DR: In this article, the authors provided a way of assessing performance in for-profit sectors, such as, textile factories of Nanjing Textiles Corporation, China The methods are closely related to the Farreal efficiency measure or data envelopment analysis (DEA).
Abstract: This paper provides a way of assessing performance in for-profit sectors, such as, textile factories of Nanjing Textiles Corporation, China The methods are closely related to the Farreal efficiency measure or data envelopment analysis (DEA) The paper studies the following three problems: (1) whether factory is operating at the minimum point of the long-run average cost curve; (2) whether there exists costless reduction in input; and (3) whether factory happens input congestion The results show that the economic efficiency of textile factories in 1989 was worse than that in 1988, and different economic systems, state ownership and collective ownership may lead to distinct performances
27 Apr 1993
TL;DR: A novel method of noise reduction of speech based on direct modulation of LPC (linear predictive coding) coefficients with respect to the noise-to-signal energy ratio (NSR) that is incorporated in an HMM-based speech recognition system using LPC-derived cepstral features.
Abstract: A novel method of noise reduction of speech based on direct modulation of LPC (linear predictive coding) coefficients is proposed. This method introduces higher-order derivatives of LPC coefficients with respect to the noise-to-signal energy ratio (NSR). With these derivatives, the noisy LPC coefficients are refined flexibly and efficiently to reduce noise contaminations. This method only needs the environmental NSR, and does not require knowledge of the probability distribution of the noise. This enhancement method is incorporated in an HMM (hidden Markov model)-based speech recognition system using LPC-derived cepstral features. A pronounced recognition error rate reduction is obtained after the speech enhancement. >
TL;DR: In this article, a stable polymer liquid crystal Langmuir-blodgett films are prepared to align nematic liquid crystals homeotropically, and the surface pressure independent alignment property is studied.
TL;DR: In this article, a substitute chromium brush plating layer was proposed for wear resistance at high speed and heavy load, and the mechanism of its excellent wear resistance under high speed, heavy load and lubrication was described.
TL;DR: In this article, a composite cylindrical hydrophone composed of PVDF piezoelectric film and an organic outer shell is presented, which possesses many good properties, such as high sensitivity, flat frequency response, flat phase response, very low acceleration response and high stability.
Abstract: In this paper, a composite cylindrical hydrophone composed of PVDF piezoelectric film and an organic outer shell is presented. It possesses many good properties, such as high sensitivity, flat frequency response, flat phase response, very low acceleration response and high stability. The hydrophone has been successfully applied to towed arrays in shallow sea. The transducing material used in the hydrophone, PVDF piezoelectric film, is also reported.
TL;DR: In this article, the microscopic molecular structures of polyimide Langmuir-Blodgett (LB) films were investigated using atomic microscopy (AFM) and they showed that polyimides have a well-ordered structure for horizontal and vertical deposition.
TL;DR: A discretization method named NOSU (nonoscillatory streamline upwind) for the convection-diffusion equation is developed, which substantially eliminates the interior and boundary layer oscillations and efficiently reduces the crosswind effect.
Abstract: Several representative discretization schemes for the drift-diffusion (or convection-diffusion) equation are reviewed. After the discussion of the drawbacks being inherent in the previous approaches, a discretization method named NOSU (nonoscillatory streamline upwind) for the convection-diffusion equation is developed. The NOSU approach substantially eliminates the interior and boundary layer oscillations and efficiently reduces the crosswind effect. A popular discriminating test problem is analyzed with the present method and some previous approaches. The numerical results demonstrate the superiority of the present method over the previous approaches in accurately solving the convection-diffusion equation. >
TL;DR: In this article, a simple quadrilateral hybrid stress element is presented for the analysis of laminated orthotropic and anisotropic plates, and the initial trials of layer stresses are pretreated by an energy constraint.
19 Oct 1993
TL;DR: The so-called Sequence-Decoupled Newton-Raphson Method used for three phase load flow study is proposed and its advantages of high accuracy, high speed, reliable convergency as well as suitability for parallel processing are verified.
Abstract: In this paper, three sequence-decoupled models of unsymmetrical transmission lines are established first. By combining these models with the well-known Newton-Raphson algorithm, the so-called Sequence-Decoupled Newton-Raphson Method used for three phase load flow study is proposed. The computation accuracy, computation speed and convergency character of this method are then investigated. From this investigation, its advantages of high accuracy, high speed, reliable convergency as well as suitability for parallel processing are verified. This method can also be extended to the three phase harmonic load flow study. >
TL;DR: In this article, the structural evolution from amorphous, microcrystalline to poly-crystaline Ge films has been achieved using a conventional plasma enhanced chemical vapour deposition system by the decomposition of H 2 -diluted GeH 4 gas plasma.
01 Oct 1993
TL;DR: In this article, a mixed technique is presented for calculating the radar cross-section characteristics of a dielectric-coated conducting cylinder with TE-wave incidence loaded with periodic metallic strips.
Abstract: A mixed technique is presented for calculating the radar cross-section characteristics of a dielectric-coated conducting cylinder with TE-wave incidence loaded with periodic metallic strips. The technique is based on the spectral-domain method (SDM), conjugate gradient method (CGM) and fast Fourier transform (FFT). Since the property of circular Toeplitz matrix has been used, only memory directly proportional to NsNb (Ns is the number of strips and Nb is the number of basis functions for approximating the currents on the strips) is needed, which allows treatment of the cylinder loaded with tens or even hundreds of strips. The RCS of a dielectric-coated conducting cylinder loaded with many periodic metallic strips are first calculated. Numerical results show that the RCS can be effectively controlled by adjusting the period or the spaces between strips.
TL;DR: In this article, the authors developed a method which can be used to compute the conductivity of an organic semiconductor, which is used to calculate the conductivities of Cu-TCNQ and Ag-TNCNQ.
Abstract: This paper develops a method which can be used to compute the conductivity of an organic semiconductor. The method is used to compute the conductivities of Cu-TCNQ and Ag-TCNQ. The results coincide with experimental results. Analysis of the two complexes reveals that the arrangement of TCNQ is the main factor affecting their conductivities.