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Showing papers by "South China University of Technology published in 1993"


Journal ArticleDOI
01 Apr 1993
TL;DR: A sliding-mode control algorithm combined with an adaptive scheme, which is used to estimate the unknown parameter bounds, is developed for the trajectory control of robot manipulators and shows that in the presence of the uncertainties, which are assumed to be unbounded and rapidly varying, the closed-loop system can still be stabilized.
Abstract: A sliding-mode control algorithm combined with an adaptive scheme, which is used to estimate the unknown parameter bounds, is developed for the trajectory control of robot manipulators. The major contribution of this methodology lies in the use of a special matrix, called the regressor, which makes it possible to isolate the unknown parameters from the robotic dynamics. Based on the upper bounds of those unknown parameters, which are estimated by a simple adaptive law, the proposed VSS (variable-structure-system) controller guarantees the stability of the closed-loop system. The robustness analysis shows that in the presence of the uncertainties, which are assumed to be unbounded and rapidly varying, the closed-loop system can still be stabilized. Chattering is reduced by using the boundary layer technique. Simulation results show the validity of the proposed algorithm. >

131 citations


Journal ArticleDOI
TL;DR: In this paper, thermal fatigue cycling and hot corrosion attack of plasma-sprayed ZrO 2 and Al 2 O 3 coatings were studied and two types of extraction replicas from the coating surface and a cross-section of the bond coat on the substrate were observed.

44 citations


Journal ArticleDOI
TL;DR: In this paper, the error expansion of the iterated collocation method for nonlinear Volterra integral equations at mesh points is shown to admit an error expansion in powers of stepsize h, beginning with a term h p.

33 citations


Journal ArticleDOI
TL;DR: In this article, the optical transmission through a class of 1D quasiperiodic lattices, for which the substitution rules are B→BA, and A→BAB, was studied.

16 citations


Journal ArticleDOI
TL;DR: This paper discusses the bidirectional associative memory model from the matched-filtering viewpoint and offers it a new interpretation and shows that the modified model performs much better than the original BAM in terms of memory capacity and error correction capability.
Abstract: This paper discusses the bidirectional associative memory (BAM) model from the matched-filtering viewpoint and offers it a new interpretation. Our attention is focused on the problem of stability and attractivity of equilibrium states. Several sufficient and/or necessary conditions are presented. To improve the BAM performance, an exponential function is used to enhance the correlations between the binary vectors of the retrieval key and that of the stored pattern similar to the key. The modified model is shown to be asymptotically stable. Theoretical analysis and simulation results demonstrate that the modified model performs much better than the original BAM in terms of memory capacity and error correction capability. >

16 citations


Journal ArticleDOI
TL;DR: In this article, seven ionized gel samples of poly(acrylic acid) made by radical polymerization and having stoichiometric neutralization degree (f) ranging from 0 to 1, were examined.

16 citations


Proceedings ArticleDOI
19 Oct 1993
TL;DR: This paper presents the learning algorithm of a neural network being applied to identification of affine nonlinear systems, and proposes a neural-network-based model reference adaptive control approach, showing that this method is feasible.
Abstract: This paper presents the learning algorithm of a neural network being applied to identification of affine nonlinear systems, and proposes a neural-network-based model reference adaptive control approach. The theorems on exponential stability of the system are proven. Simulation results show that this method is feasible. >

15 citations


Journal ArticleDOI
TL;DR: An adaptive sliding mode scheme is developed for accurate tracking control of robotic manipulators by coupling on-line estimation of unknown manipulator and payload parameters to sliding mode control, and the introduction of a boundary layer solves the problem of chattering.
Abstract: An adaptive sliding mode scheme is developed for accurate tracking control of robotic manipulators By coupling on-line estimation of unknown manipulator and payload parameters to sliding mode control, tracking performance is effectively improved The introduction of a boundary layer solves the problem of chattering and provides a consistent rule on when to stop adaptation The algorithm is computationally simple, because of an effective exploitation of the structure of manipulator dynamics The approach is demonstrated by simulations

12 citations


Journal ArticleDOI
TL;DR: In this paper, the influence of temperature and shear rate on the flow behavior of high density polyethylene (HDPE) melts during extrusion was investigated by using a Ceast Rheovis 2100 capillary rheometer which was manufactured by the Ceast Co. in Italy.
Abstract: The influence of temperature and shear rate on the flow behavior of high density polyethylene (HDPE) melts during extrusion has been investigated by using a Ceast Rheovis 2100 capillary rheometer which was manufactured by the Ceast Co. in Italy. It was found that the entry pressure drop for the samples was very low during extrusion, the relationship between shear stress and shear rate did not obey the power law strictly, and the phenomenon of shear-induced crystallization was easily produced when temperature was near the melting point of the samples, even though the shear rate was not high. The dependence of the shear viscosity for the samples on temperature can be described by using the Arrhenius equation. © 1993 John Wiley & Sons, Inc.

12 citations


Proceedings ArticleDOI
15 Dec 1993
TL;DR: In this article, a unified approach is developed to deal with both the Lyapunov stability and the practical stability of delay stochastic systems, based on the comparison principles, a unified framework for dealing with the two types of stability properties is presented.
Abstract: In this paper, both Lyapunov stability in the pth mean and practical stability in the pth mean are defined for the delay stochastic systems. By applying the Lyapunov-like functions and the theory of differential inequalities, comparison principles are set up for the nonlinear delay stochastic systems. Based on these comparison principles, a unified approach is developed to deal with both the Lyapunov stability and the practical stability. Criteria are established for various types of Lyapunov stability and practical stability of the delay stochastic systems. By these criteria, the stability properties (Lyapunov and practical) of the delay stochastic systems can be obtained by testing the corresponding stability properties of the auxiliary delay deterministic systems. >

11 citations


Journal ArticleDOI
TL;DR: In this article, the dispersive melting model has been shown to have a number of advantages over the Maddock melting model: the mechanical power consumption can be decreased; the polymer temperature profile is more uniform and its average temperature is lower; melting can be accelerated and hence the total melting length shortened.
Abstract: Studies on the melting in a single-screw extruder have mainly concentrated on the Maddock melting mechanism The dispersive melting mechanism, named by us, is of great practical utility A six-block physical model is first proposed for the dispersive melting mechanism in the present study Then nonisothermal non-Newtonian mathematical models for the dispersive and Maddock melting mechanisms are developed It has been demonstrated that the dispersive melting model has a number of advantages over the Maddock melting model: the mechanical power consumption can be decreased; the polymer temperature profile is more uniform and its average temperature is lower Furthermore, melting can be accelerated and hence the total melting length shortened © 1993 by John Wiley & Sons, Inc

Journal ArticleDOI
TL;DR: The numerical simulation shows that the electronic energy spectra of a three-tile model of one-dimensional quasiperiodic lattices are also Cantor-like, but have different self-similarity from that of the Fibonacci lattice.
Abstract: Several aspects of the electronic properties of a three-tile model of one-dimensional quasiperiodic lattices have been studied. A canonical procedure to obtain the trace map is presented. The numerical simulation shows that the electronic energy spectra are also Cantor-like, but have different self-similarity from that of the Fibonacci lattice. We have provided a P, Q matrix approach to study the zero-energy eigenstates, and a pseudo-seven-cycle of the matrix map has been found. An exact real-space renormalization-group decimation approach has been used to calculate the local density of states. The numerically obtained spectra are in good agreement with previous analytical results

Journal ArticleDOI
TL;DR: In this article, a statistical analysis for the tensile first failure and hybrid effect of unidirectional interply hybrid composites is presented, where a shear-lag model is applied to solve the stress redistributions after the breakage of low-elongation fibers.

Journal ArticleDOI
TL;DR: In this article, the spectral structure of polyaniline films was analyzed with emphasis on the evolution of the electronic structure from an insulating to a conducting polymer, and the threshold energy and the broadening parameter as well as the dimension were determined by the fractional derivative spectrum technique.

Journal ArticleDOI
TL;DR: In this paper, a shear-lag model is presented for analysis of stress concentration of fibres adjacent to a crack in unidirectionally fiber-reinforced composites.
Abstract: A shear-lag model is presented in this paper for analysis of stress concentration of fibres adjacent to a crack in unidirectionally fibre-reinforced composites. The analytic expressions of stress concentration factors of fibres adjacent to the tip of a crack with r broken fibres are obtained by using this model. The maximum stress concentration factors of the fibre at the tip of the crack are calculated, and the numerical results show little difference with Hedgepeth's [1]. In addition, the concept of the effective stress concentration factor is used since shear-lag analysis overestimates stress concentration of fibres [2], and the affected length of a crack-tip fibre is defined by value of the stress concentration factor. The affected length has clear physical meaning and increases gradually with extension of the crack, which is in accord with the actual case. Finally, based on the previous investigation, statistical analysis of strength of unidirectionally fibre-reinforced composites is done by applying the method of the critical crack core model [3, 4]. The numerical results are close to the experimental results, and those obtained by using the effective stress concentration factors approach the experimental results most closely.

Journal ArticleDOI
TL;DR: In this article, the effects of dopants and processing technology on the dielectric properties and electrostrictive properties of PMN-based relaxer ferroelectric materials are discussed in detail.
Abstract: For servo-type actuator applications, temperature-stable high electric-field-induced-strain electrostrictive lead magnesium niobate (PMN)-based relaxer ferroelectric materials are needed. The synthesis technique of the PMN-based composition with 100% perovskite phase is described. The effects of dopants and processing technology on the dielectric properties and electrostrictive properties are discussed in detail.

Proceedings ArticleDOI
02 May 1993
TL;DR: An implicit adaptive inverse dynamics control scheme for robot manipulators is presented, where instead of estimating manipulator parameters, the feedback gain is directly updated according to the bounds of uncertainties of the robotic system.
Abstract: An implicit adaptive inverse dynamics control scheme for robot manipulators is presented. Instead of estimating manipulator parameters, the feedback gain is directly updated according to the bounds of uncertainties of the robotic system. Two theorems are proven, and the resulting algorithm can tolerate the variation of physical parameters to some extent. The controller parameters have a certain relation to the desired position and velocity accuracy, such that the choice for them is easy. Simulation results verify the effectiveness of the approach. >

Journal ArticleDOI
TL;DR: In this paper, a cobalt phthalocyanine (CoPc) was prepared in situ as a guest molecule in the layered host antimony hydrogen phosphate, which has also been called a phosphatoantimonic acid, HSb(PO4)2, here denoted as (HSbP2).

Journal ArticleDOI
TL;DR: Wang et al. as discussed by the authors investigated private entrepreneurs in China and found that the major cause for those problems lies in the Chinese government changing policies and regulations in relation to private enterprises too frequently.
Abstract: Tan (1987) and Dandridge and Flynn (1988) argue that both internal and external environments favour entrepreneurship development in China. Nevertheless, research studies about Chinese entrepreneurs only select Geteihu —one-man businesses (Tuan et al. 1986), private merchants (Wank, 1990), Xiangzhen Qiye—rural enterprises (Nolan and Dong, 1989), and corporate entrepreneurs (Siu, 1992) as sampling units. Siying Qiyejia, private entrepreneurs or owner-managers, especially those in manufacturing industries and services sectors are neglected. According to the classification of the Chinese government, private enterprises are businesses owned by individuals with 8 or more employees (Young, 1991). (For those below 8, they are classified as one-man business.) They mainly participate in the manufacturing and services sectors (Guo, 1992). This paper attempts to address the imbalance and also adds new insights to the body of knowledge by investigating private entrepreneurs in China. 70 owner-managers in Guangzhou, the business centre in South China, were selected for sampling. In-depth personal interviews with 14 private entrepreneurs were successfully arranged. The problems encountered by private entrepreneurs in China in ranking order are taxation, credit, human resource and growth. They indicate that the major cause for those problems lies in the Chinese government changing policies and regulations in relation to private enterprises too frequently. Most private entrepreneurs use the ‘let-it-be’ approach to handle those problems. However, a small portion of them get around them by establishing joint ventures with overseas investors. Under the joint venture umbrella, they no longer suffer from stringent controls imposed by government officials, but rather, be able to enjoy better investment incentives.


Journal ArticleDOI
TL;DR: In this article, two structure-variable homotopy algorithms called local straightenup method and global straighten-up method are developed to approximate the optimal homotope, and an adaptive step-size control strategy for these algorithms is proposed respectively.
Abstract: This paper deals with the monotone homotopy methods for solving the system of nonlinear equations. In Sect. 2 the homotopy with a distancemonotone homotopy path is discussed and it is proved that a homotopy with a given structure has a distance monotone homotopy path under some regular conditions. Then two structure-variable homotopy algorithms called local straighten-up method and global straighten-up method are developed to approximate the optimal homotopy, and an adaptive step-size control strategy for these algorithms is proposed respectively. A new method for analyzing the convergence is presented, which is based on the geometrical properties of the algorithm. Then the convergence of the algorithm is proved under certain regular conditions. Finally two numerical examples are given to illustrate the effectiveness of the above two algorithms.

Journal ArticleDOI
TL;DR: In this article, the existence and nonexistence of axially symmetric solution for quasilinear elliptic systems wlth inhomogeneous term is discussed. But the nonexistence is not proved.
Abstract: (1993). Existence and nonexistence of nontrivial axially symmetric solution for quasilinear elliptic systems wlth inhomogeneous term. Communications in Partial Differential Equations: Vol. 18, No. 9-10, pp. 1477-1491.

Journal ArticleDOI
01 Jan 1993-Carbon
TL;DR: In this paper, the adsorption and oxidation of cyanide solutions on activated carbon have been investigated to examine whether or not this process involves chemisorption of copper compound on the oxidation of Cyanide.

Journal ArticleDOI
TL;DR: In this paper, the problems of developing flow under unsteady oscillatory condition are studied, assuming that the tapered angle is small, and the formula of velocity distribution is obtained.
Abstract: Assuming that the tapered angle is small, the problems of developing flow under unsteady oscillatory condition are studied in this paper. The formula of velocity distribution is obtained. The analyses for the results show that the blood flow in a converging tapered vessel remains a developing flow throughout the length, and the effects of tapered angle on the developing flow are increased with the increment of the tapered angle.

Journal ArticleDOI
TL;DR: In this paper, a new class of one-dimensional qusiperiodic lattices, for which substitution rules are B→BA, and A→BAB, is studied.
Abstract: We study the on-site model of a new class of one-dimensional qusiperiodic lattices, for which the substitution rules areB→BA, andA→BAB. By means of the renormalization-group approach, a interesting multifractal specrral behavior has been found, which has been confirmed by numerical simulation. A Cantor-like energy spectra is obtained by using the Kohmoto-Kadanaff-Tang (KKT) renormalization-group method. Three kinds of wave-function behavior (extended, localized, and intemediate states) are definitely found.

Proceedings ArticleDOI
19 Oct 1993
TL;DR: In this paper, an adaptive inverse dynamics robotic control algorithm based on Lyapunov stability theory is proposed to improve the global stability of the robotic system, which is easy to implement and robust to parameter uncertainty and payload variation.
Abstract: This paper addresses an adaptive inverse dynamics robotic control algorithm Based on Lyapunov stability theory, the theorems on the global stability of robotic system are proven The proposed algorithm is easy to implement and the robotic system is robust to parameter uncertainty and payload variation Simulation results show the effectiveness of the scheme >

Journal ArticleDOI
TL;DR: In this article, the constant boundary value problem for a class of quasilinear elliptic systems is studied and the existence of a nonconstant solution is proved by discussing the minimization problem for the relaxed energy.
Abstract: We study the constant boundary value problem for a class of quasilinear elliptic systems. The existence of a nonconstant solution is proved by discussing the minimization problem for the relaxed energy. As a by-product, we show that generally the Pohozaev identity does not hold for H1-weak solutions.

Journal ArticleDOI
TL;DR: In this paper, an ellipsometric spectrum analysis of polyaniline has been performed in the UV-visible range (1.4-4.8 eV photon energy region).
Abstract: We report the ellipsometric spectrum studies on a new kind of conducting polymers, polyaniline. In the UV-visible range (1.4-4.8 eV photon energy region) the absorption coefficient, the complex dielectric function and the refractive index of polyaniline as functions of photon energy are obtained. The spectra of nonconducting and fully conducting polyaniline have been analyzed and discussed. The experimental results show that the emeraldine base form of polyaniline has a large energy gap (Eg ~ 3.6 eV) and its absorption spectrum shows a broad exciton absorption peak centered at 2 eV. The absorption spectrum of emeraldine salt after protonation have four absorption peaks centered at 1.5, 1.83, 3.0 and 3.88 eV. We also investigated the spectrum evolution of the samples from nonconducting (?<10-9?-1?cm-1) to conducting (?10+1?-1?cm-1) states, and give the dielectric function and the refractive index of the samples.

Journal ArticleDOI
01 Feb 1993
TL;DR: In this article, the analysis of unilateral finlines has been completed using a new method, regular solution of singular integral equation (RSSIE), which is demonstrated that the results obtained by this method are more accurate than those computed by the spectral domain method by comparing the data measured.
Abstract: The analysis of unilateral finlines has been completed using a new method, regular solution of singular integral equation (RSSIE). It is demonstrated that the results obtained by this method are more accurate than those computed by the spectral domain method (SDM) by comparing the data measured. In some special cases where the results can be obtained exactly, the new method gives more accurate values than those calculated by the SDM. Dominant and higher-order modes can be calculated effectively and accurately. The computer time required by this method is decreased considerably compared with SDM (about 1/45 of the time required by SDM).

01 Jan 1993
TL;DR: In this paper, the variation of parameters formula of nonlinear large scale systems containing measures was established by means of the lumped Picard iteration method, which avoided the difficulties of constructing Lyapunov function.
Abstract: In this paper, we established the variation of parameters formula of nonlinear large scale systems containing measures. By means of the lumped Picard iteration method, which avoided the difficulties of constructing Lyapunov function, we studied the stability, uniform stability, asymptotic stability, uniform asymptotic stability, and exponential stability properties of nonlinear measure large scale systems.