Showing papers by "South China University of Technology published in 1994"
TL;DR: An improved Razumikhin-type theorem is established, and the advantage of theestablished theorem for reducing conservatism is discussed, and a simple asymptotic stability condition is deduced as an application of the established theorem.
Abstract: An improved Razumikhin-type theorem is established, and the advantage of the established theorem for reducing conservatism is discussed. For a class of time-delay systems, a simple asymptotic stability condition is deduced as an application of the established theorem. Two illustrative examples are given to show the superiority of the results to those in the literature. >
117 citations
TL;DR: In this paper, the Richardson extrapolation was applied to the trapezoidal Nystrom solution of the linear Volterra-Fredholm equation to increase the accuracy of the numerical solution greatly.
52 citations
Journal Article•
TL;DR: In this paper, a predictive control strategy based on the Hammerstein model is proposed and evaluated for pH neutralization, high purity separations and some chemical reactors can be very difficult due to their highly nonlinear nature.
Abstract: The control of processes such as processes such as pH neutralization, high purity separaqtions and some chemical reactors can be very difficult due to their highly nonlinear nature. In this peper, a predictive control strategy based on the Hammerstein model is proposed and evaluated for such processes. The Hammerstein models are identified by two approaches, simultaneous identification and sequential identification. In particular, a modified Hammerstein model is proposed to overcome the disadvantages of the standard model for controller design. Simulation studies for a pH neutration process indicate that predictive control based on either Hammerstein model can provide much better setpoint tracking and disturbance rejection than well-tuned PID controllers.
39 citations
TL;DR: In this paper, the internal friction and elastic modulus were measured vs. temperature (100 T 3 driven electrostatically in flexural vibration at resonance frequencies between 2 and 4 kHz.
29 citations
TL;DR: In this paper, a new mechanism of adhesion called conjugate interpenetration of networks across interfaces, which is suitable for IPN adhesives and polymer substrates, was put forward.
Abstract: Polyether-based polyurethane/poly (methyl methacrylate-co-ethyleneglycol dimethacrylate) interpenetrating polymer networks [PU/P (MMA–co–EGDMA)-IPNs] were synthesized and used as adhesives to adhere vulcanized natural rubber (NR) and soft polyvinyl chloride (PVC). The structure and morphology of the IPN adhesives in bulk and near the adhesive/substrate interfaces were investigated. A new mechanism of adhesion called conjugate interpenetration of networks across interfaces, which is suitable for IPN adhesives and polymer substrates, was put forward. According to this mechanism, while forming simultaneous interpenetrating networks in the adhesive, the monomers in the IPN adhesive can permeate polymer substrates and polymerize in situ to form gradient IPNs, thereby producing conjugate three-component IPNs near the adhesive/substrate interfaces. It is the conjugate interpenetration of the networks across the interfaces that strengthens interfacial combination remarkably and results in high bond strength of IPN adhesives. © 1994 John Wiley & Sons, Inc.
27 citations
TL;DR: The graft copolymerization of styrene and methyl methacrylate on SBR latex particles in the core-shell emulsion process was conducted in a 600 mL glass stirred vessel with the BPOFe2+ redox initiator as discussed by the authors.
Abstract: The graft copolymerization of styrene and methyl methacrylate on SBR latex particles in the core–shell emulsion process was conducted in a 600 mL glass stirred vessel with the BPOFe2+ redox initiator. The effects of the principal factors such as the polymerization temperature, monomer-to-polymer ratio, the frequency of monomer addition and conversion on the grafting degree, and the grafting efficiency were studied. The surface-controlled process model was proposed to describe the grafting mechanism. © 1994 John Wiley & Sons, Inc.
22 citations
TL;DR: In this article, the numerical solution of two-dimensional linear Volterra integral equation by collocation and iterated collocation is considered and the asymptotic error expansion is obtained.
19 citations
02 Mar 1994
TL;DR: In order to increase input information, a `higher-order' terms of input patterns by using functional-linked of the input patterns are introduced and the approximation property of the NN has a powerful approximation capability than that of conventional BP neural network.
Abstract: This paper describes a modified feedback BP NN: Sigma-Pi-linked ((Sigma) -(Pi) ) model. In order to increase input information, a `higher-order' terms of input patterns by using functional-linked of the input patterns are introduced. Finally, the approximation property of the NN has a powerful approximation capability than that of conventional BP neural network.
13 citations
TL;DR: In this article, the error expansion for the Nystrom method for one-dimensional nonlinear Fredholm integral equations of the second kind is considered and Richardson's extrapolation can be performed on the solution, and this will greatly increase the accuracy of the numerical solution.
Abstract: In this paper the asymptotic error expansion for the Nystrom method for one-dimensional nonlinear Fredholm integral equations of the second kind is considered. We show that the Nystrom solution admits an error expansion in powers of the step-sizeh. Thus Richardson's extrapolation can be performed on the solution, and this will greatly increase the accuracy of the numerical solution.
13 citations
05 Dec 1994
TL;DR: In this article, a new actuator for a robotic hand, composed of two NiTi shape memory alloy (SMA) springs, is studied, and it is found that at a shear strain of 1.5% (a value below which NiTi alloy has a long cycling life) the load at 90/spl deg/C is 8.5 times greater than at 10/spl/C.
Abstract: A new actuator for a robotic hand, composed of two NiTi shape memory alloy (SMA) springs, is studied. First, the properties of NiTi SMA springs, including load-displacement dependences at various temperatures, resistance-temperature dependence, and recovery-temperature dependence are tested and analyzed. It is found that at a shear strain of 1.5% (a value below which NiTi alloy has a long cycling life) the load at 90/spl deg/C is 8.5 times greater than at 10/spl deg/, the transformation temperature A/sub f/ (austenite-finish temperature) increases with decreasing aging temperature and/or with increasing aging time. Next, a new actuator with two NiTi SMA springs for a robotic hand is studied. It is found that with this new actuation model, the serious limitations of heating and cooling speed which depend on heat transfer processes and make SMA motions slow, are greatly improved. >
12 citations
TL;DR: An adaptive signal enhancer that is capable of tracking the variation of visual evoked potential (VEP) from trial to trial as well as improving SNR is described.
Abstract: The method of ensemble averaging (EA), commonly used to improve signal-to-noise ratio (SNR) in evoked potential measurements, loses potentially useful information regarding re sponse variability across trials. Due to the usually low SNR, it is difficult to extract the response from individual trials. The present paper describes an adaptive signal enhancer (ASE) that is capable of tracking the variation of visual evoked potential (VEP) from trial to trial as well as improving SNR. This ASE requires two inputs: a primary input, which is the raw noise-corrupted response, and a reference input, which is designed for an optimal performance of ASE. We used moving ensemble averaging (MEA) to form the dynamic reference input. Experimental results in humans show a satisfactory performance of the ASE in determining VEP to single stimulus and in tracking the temporal changes of the signal.
TL;DR: In this paper, the effect of pressure and temperature on the melt density of HDPE was investigated, and the results revealed that a fractional MI < 1 g 10 min−1 has a different sensitivity to pressure/temperature to that for a MI of greater than 1g 10 min −1.
TL;DR: Two mathematical description theorems of sliding modes are obtained using a novel analysis approach and it is shown that the system is made insensitive to system uncertainties once the sliding manifold is reached.
05 Dec 1994
TL;DR: In this paper, the authors developed an approach for online detection of incipient faults in single phase squirrel-cage induction motors through the use of artificial neural nets (ANNs).
Abstract: This paper develops a novel approach for online detection of incipient faults in single phase squirrel-cage induction motors through the use of artificial neural nets (ANNs). Two of the most common types of incipient faults are indicated: stator winding fault and bearing wear under constant load torque conditions. From the description of motor dynamics, the nonlinear relation of motor parameters also indicated. Simulation results show that the application of ANN to fault diagnosis of motors is reliable. >
TL;DR: In this paper, the authors studied the stability properties of nonlinear measure large scale systems by means of the lumped Gauss-Seidel iteration method, which avoided the difficulties of constructing Lyapunov functions.
Abstract: In this paper, we studied the stability properties of nonlinear measure large scale systems by means of the lumped Gauss-Seidel iteration method, which avoided the difficulties of constructing Lyapunov functions. The explicit algebraic criteria of the stability, uniform stability, asymptotic stability, uniform asymptotic stability, and exponential stability for nonlinear measure large scale systems are established.
TL;DR: In this paper, the authors used a transfer matrix method to study the interface polariton modes in three-tile quasiperiodic semiconductor superlattices and showed that the distribution of the interfaces depends obviously on the structure of the quasiprocessor.
Abstract: Using a transfer matrix method, we study the interface polariton modes in three-tile quasiperiodic semiconductor superlattices. It is shown that the distribution of the interface polariton modes depends obviously on the structure of the quasiperiodic superlattice.
TL;DR: In this article, with the help of the Drazin inverse, the variation of the parameters formula of singular measure differential systems is obtained, and the problem of boundary input and boundary output (BIBO) is investigated.
TL;DR: In this paper, a modified shear-lag model was proposed for solving the stress redistributions resulting from both failure of some layers and breakage of fibres in the high-elongation layers.
05 Dec 1994
TL;DR: In this article, an approach of High Frequency Network Averaging (HFNA) is presented for analysis of quasi-resonant converters (QRCs), where the elements whose currents vary very fast are replaced by dependent sources controlled by low-frequency variables and nonlinear structure-invariant equivalent circuits of QRC's can be obtained.
Abstract: An approach of High Frequency Network Averaging (HFNA) is presented for analysis of Quasi Resonant Converters (QRC's). The elements whose currents (or terminal voltages) vary very fast are replaced by dependent sources controlled by low-frequency variables and nonlinear structure-invariant equivalent circuits of QRC's can be obtained. This new approach and its resulting models are circuit-oriented and helpful to the analysis and design of QRC's. >
TL;DR: A fuzzy match inference strategy is proposed to assess design schemes with rules in parallel in the synthesis of multicomponent separation sequences and it is shown from several examples that the inference strategy yields promising results in quantitative evaluation of process synthesis and combinatorial optimization.
Abstract: Symbolic representation and sequential processing of information in most expert systems have made it difficult to represent continuous variables and to model interactions among different parts of a large process system. This paper proposes a new approach, principally aimed at function oriented engineering design problems. Continuous variables and qualitative information are treated as fuzzy sets. A fuzzy match inference strategy is proposed to assess design schemes with rules in parallel. The fuzzy match inference strategy is then extended to multi-step decision making in the synthesis of multicomponent separation sequences. The new concepts have been implemented in a prototype expert system, where the selection of separation technologies and sequencing of separators are approached in an integrated manner. It is shown from several examples that the inference strategy yields promising results in quantitative evaluation of process synthesis and combinatorial optimization.
La representation symbolique et le traitement sequentiel de l'information de la plupart des systemes experts ont rendu difficile la representation des variables continues et la modelisation des interactions des differentes parties des procedes de grande taille. Dans cet article, on propose une nouvelle methode, principalement destinee aux problemes de conception en ingenierie pouvant ětre decrits par des fonctions. Les variables continues et les donnees qualitatives sont traitees comme des ensembles flous. On propose une strategie d'inference a concordance floue afin d'evaluer les schemas de conception avec regles en parallele. La strategie d'inference a concordance floue est ensuite etendue a une prise de decisions multietagee dans la synthese des sequences de separation a composants multiples. Le nouveaux concepts ont ete introduits dans un prototype de systeme expert, dans lequel la selection des technologies et le sequencage des separateurs sont traites de maniere integree. On montre par plusieurs exemples que la strategie d'inference donne des resultats prometteurs dans I' evaluation quantitative de la synthese des procedes et I'optimisation combinatoire.
TL;DR: In this paper, the general solution of the conditional Cauchy functional equation was determined for a large class of fields K, where K is a field belonging to a certain class, and G is an abelian group.
Abstract: We determine the general solution of the functional equation
$$\psi(x+y)=g(xy)+h(x-y),\ \ \ x,y\in\ {\rm \bf K}$$
for ψ,g,h: K → G, where K is a field belonging to a certain class, and G is an abelian group. This functional equation was one of the several treated by Abel in his 1823 manuscript. Recently, this equation was solved by Aczel and also independently by Lajko without any regularity assumption when K = G = ℜ (reals). We consider also the conditional Cauchy equation
$$G(x^{2}- y^{2})=G(x^{2})- G(y^{2})$$
for G: K →> G. For a large class of fields K, this forces G to be a morphism from the additive group of K into G. For us, additional motivation for studying these functional equations came from a characterization problem related to generalized quadratic differences of functions.
TL;DR: In this article, the effect of short-range order on the electrical resistivity in multicomponent solid solutions is studied by applying the model of Rossiter and Wells in which a spherical Fermi surface and s-s scattering mechanism are assumed.
Abstract: The effect of short-range order on the electrical resistivity in multicomponent solid solutions is studied by applying the model of Rossiter and Wells in which a spherical Fermi surface and s-s scattering mechanism are assumed. For the description of the state of short-range order in multicomponent systems a set of generalized Warren-Cowley parameters α i XY are defined, based on the same assumptions that were used in the earlier treatments of binary alloys, a linear combination between the short-range order induced resistivity and α i XY is obtained. The possibility of the experimental verification of the derived relationship is further discussed
22 Aug 1994
TL;DR: In this article, a novel non-uniformly sampling delta modulation (NSDM) technique is investigated; its characteristics and implementation scheme are also described, and the results have shown that the technique has the advantages of a higher coding efficiency, and a larger signal-to-noise ratio as compared to that of the conventional DM.
Abstract: In this paper, a novel nonuniformly sampling delta modulation (NSDM) technique is investigated; its characteristics and implementation scheme are also described. The results have shown that the technique has the advantages of a higher coding efficiency, and a larger signal-to-noise ratio as compared to that of the conventional DM. >
TL;DR: In this article, a regular solution of singular integral equation (RSSIE) was used to analyze the spectrum properties of a shielded transmission line, where the uniqueness of the fields is determined by the regularity conditions for the solutions of the singular integral equations at the edges of the metal strips.
Abstract: The analysis of shielded transmission lines has been completed using a new method: Regular solution of singular integral equation (RSSIE). Here, an integration procedure is adopted and the uniqueness of the fields is determined by the regularity conditions for the solutions of the singular integral equations at the edges of the metal strips. This leads to more rapid convergence of the series solutions, and enables the analysis of any kind of shielded planar transmission line. It is demonstrated that the results obtained by the proposed method are more accurate than those computed by the spectral domain method (SDM) in comparison with the data measured. In some special cases where the results can exactly be obtained, the proposed method gives more accurate values than those calculated by the SDM. Dominant and higher order modes can be calculated effectively and accurately. The investigation of convergence shows that not only dominant mode but also higher order modes converge rapidly. The computer time required by this proposed method decreases considerably in comparison with SDM. >
TL;DR: In this article, the chain transfer method was adopted to study the graft copolymerization of butyl acrylate onto poly(vinyl chloride) (PVC) in emulsion.
TL;DR: Theoretical studies on misoriented transformation particles and micro-cracks in transformation toughening ceramics using the Eshelby equivalent inclusion method are presented in this article.
Abstract: Theoretical studies on misoriented transformation particles and microcracks in transformation toughening ceramics are presented using the Eshelby equivalent inclusion method. The stress field, stiffness and strength were calculated. Experiments were done by the three-point bend method using Al2O3/ZrO2 ceramics and the stiffness and strength were also measured. Comparison between theoretical and test results confirmed the important role of microcracks.
TL;DR: Carboxy-terminated poly(oxyethylenes) (PEO-acid) with number-average molecular weights Mn = 8400, 3300, and 1000 were used for antielectrostatic modification of poly(ethylene terephthalate) (PET).
Abstract: Carboxy-terminated poly(oxyethylenes) (PEO-acid) with number-average molecular weights Mn = 8400, 3300, and 1000 were used for antielectrostatic modification of poly(ethylene terephthalate) (PET). The blend PET fibers containing 2.0 and 5.0 wt.-% of PEO-acids were melt-spun at 285°C with an ordinary extruder and then drawn about 4.5-fold at 80°C. The processabilities of spinning and drawing were excellent at higher molecular weights of PEO-acid. The anti-electrostatic properties of the blend fibers became also improved with increasing molecular weight of PEO-acid. Since little ester interchange reaction took place between PET and PEO-acid during meltspinning, the blend fibers could retain almost the same mechanical properties as the original PET fiber.
Carboxy-terminierte Polyoxyethylene (PEO-acid) mit zahlenmittleren Molekulargewichten Mn = 8400, 3300 und 1000 wurden zur antielektrostatischen Modifizierung von Polyethylenterephthalat (PET) verwendet. Fasern aus PET-PEO-acid-Blends mit 2,0 oder 5,0 Gew.-% PEO-acid wurden bei 285°C mit einem normalen Extruder aus der Schmelze gesponnen und anschliesend bei 80°C um das ca. 4,5fache verstreckt. Die Verarbeitbarkeit beim Verspinnen und Verstrecken war bei Verwendung von PEO-acid mit hohen Molekulargewichten ausgezeichnet. Die anti-elektrostatischen Eigenschaften wurden ebenfalls mit steigendem PEO-acid-Molekulargewicht besser. Da eine Umesterung beim Verspinnen nur in geringem Ausmas stattfand, blieben die mechanischen Eigenschaften der Blend-Fasern gegenuber den PET-Fasern nahezu unverandert.
TL;DR: In this article, the authors investigated the ultrafast dynamics of third order nonlinearities of polyaniline (PAn), doped in polymethyl mathacrylate (PMMA) films using femtosecond absorption spectroscopy.
Abstract: The ultrafast dynamics of third order nonlinearities of polyaniline (PAn) and polyaniline doped in polymethyl mathacrylate (PAn-PMMA) films are investigated using femtosecond absorption spectroscopy. An ultrafast initial exciton deformation time of about 100 fs is observed in PAn film. In PAn-PMMA film, the third-order nonlinearity results in an efficient two-photon absorption at about 2 eV.
TL;DR: In this article, exact calculations of the Glauber amplitude for C scattering at 137 GeV were carried out by expanding it into multiple scattering sequences and by classifying them into equivalent kinds.
Abstract: Exact calculations of the Glauber amplitude for \ensuremath{\alpha}${\mathrm{\ensuremath{-}}}^{12}$C scattering at 137 GeV are carried out by expanding it into multiple scattering sequences and by classifying them into equivalent kinds A comparison has been made with those based on various approximation schemes The convergence of the expansion is investigated
05 Dec 1994
TL;DR: The principle of the approach, the structure of neural networks and the new learning algorithm are interpreted, and the method is shown to be good at accuracy and speed for power system dynamic equivalents.
Abstract: This paper describes a new method for online identification of coherent generators based on multilayer feedforward neural networks. The principle of the approach,the structure of neural networks and the new learning algorithm are interpreted. Results are described for a 6-machine system and the method is shown to be good at accuracy and speed for power system dynamic equivalents. >