Showing papers by "Shanghai Jiao Tong University published in 1997"
TL;DR: In this paper, the homotopy analysis method was further improved by introducing a non-zero parameter into the traditional way of constructing a homhotopy, which can converge even in the whole region η ϵ [0, + ∞].
Abstract: In this paper, the non-linear approximate technique called Homotopy Analysis Method proposed by Liao is further improved by introducing a non-zero parameter into the traditional way of constructing a homotopy. The 2D viscous laminar flow over an infinite flat-plain governed by the non-linear differential equation f′''(η) + f(η)f″(η) 2 = 0 with boundary conditions f(0) = f′(0) = 0, f′(+ ∞) = 1 is used as an example to describe its basic ideas. As a result, a family of approximations is obtained for the above-mentioned problem, which is much more general than the power series given by Blasius [Z. Math. Phys. 36, 1(1908)] and can converge even in the whole region η ϵ [0, + ∞). Moreover, the Blasius' solution is only a special case of ours. We also obtain the second-derivative of f(η) at η = 0, i.e. f″(0) = 0.33206, which is exactly the same as the numerical result given by Howarth [Proc. Roy. Soc. London A164, 547 (1938)].
354 citations
TL;DR: In this paper, the basic ideas of a new kind of analytical technique, namely the Homotopy Analysis Method (HAM), are briefly described, and a simple but typical example is used to illustrate the validity and the great potential of the HAM.
143 citations
TL;DR: In this paper, the basic ideas of homotopy in topology are applied to give a kind of high-order Boundary Element Method (BEM) formulations for strongly nonlinear problems governed by quite general nonlinear differential operators which may not contain any linear operators at all.
Abstract: In this paper, the basic ideas of homotopy in topology is applied to give a kind of high-order Boundary Element Method (BEM) formulations for strongly nonlinear problems governed by quite general nonlinear differential operators which may NOT contain any linear operators at all. As a result, the traditional BEM which treats the nonlinear parts as the inhomogeneities is only a special case of the proposed formulations. Two simple examples are used to illustrate its effectiveness.
137 citations
TL;DR: In this article, the effects of initial geometric imperfections of the plate are included in the present study which also includes the thermal effects, and the analysis uses a mixed Galerkinperturbation technique to determine thermal buckling loads and postbuckling equilibrium paths.
Abstract: Karman-type nonlinear large deflection equations are derived according to the Reddy's higher-order shear deformation plate theory and used in the thermal postbuckling analysis. The effects of initial geometric imperfections of the plate are included in the present study which also includes the thermal effects. Simply supported, symmetric cross-ply laminated plates subjected to uniform or nonuniform parabolic temperature distribution are considered. The analysis uses a mixed Galerkinperturbation technique to determine thermal buckling loads and postbuckling equilibrium paths. The effects played by transverse shear deformation, plate aspect ratio, total number of plies, thermal load ratio and initial geometric imperfections are also studied.
122 citations
TL;DR: It is demonstrated that the PLZF and PML proteins interact with each other and colocalize onto nuclear bodies (NBs) and induction of PML expression by interferons leads to a recruitment ofPLZF onto NBs without increase in the levels of the PLL protein.
Abstract: In acute promyelocytic leukemia (APL), the typical t(15;17) and the rare t(11;17) translocations express, respectively, the PML/RARα and PLZF/RARα fusion proteins (where RARα is retinoic acid receptor α). Herein, we demonstrate that the PLZF and PML proteins interact with each other and colocalize onto nuclear bodies (NBs). Furthermore, induction of PML expression by interferons leads to a recruitment of PLZF onto NBs without increase in the levels of the PLZF protein. PML/RARα and PLZF/RARα localize to the same microspeckled nuclear domains that appear to be common targets for the two fusion proteins in APL. Although PLZF/RARα does not affect the localization of PML, PML/RARα delocalizes the endogenous PLZF protein in t(15;17)-positive NB4 cells, pointing to a hierarchy in the nuclear targeting of these proteins. Thus, our results unify the molecular pathogenesis of APL with at least two different RARα gene translocations and stress the importance of alterations of PLZF and RARα nuclear localizations in this disease.
116 citations
TL;DR: In this paper, a hybrid of genetic algorithms and dispatching rules was proposed for solving the job shop scheduling problem with sequence-dependent set-up time and due date constraints, which is more suitable for a dynamic job shop environment than the static scheduling strategy.
Abstract: In this paper, the job shop scheduling problem in a dynamic environment is studied. Jobs arrive continuously, machines breakdown, machines are repaired and due dates of jobs may change during processing. Inspired by the rolling horizon optimisation method from predictive control technology, a periodic and event-driven rolling horizon scheduling strategy is presented and adapted to continuous processing in a changing environment. The scheduling algorithm is a hybrid of genetic algorithms and dispatching rules for solving the job shop scheduling problem with sequence-dependent set-up time and due date constraints. Simulation results show that the proposed strategy is more suitable for a dynamic job shop environment than the static scheduling strategy.
108 citations
01 Jan 1997
TL;DR: A systematic adaptive control strategy which can accomplish a variety of control objectives (position control, internal force control, constraints, and optimizations) for the generalized high-dimensional robotic systems (GHDRS) without restriction on target systems is presented.
Abstract: This paper presents a systematic adaptive control strategy which can accomplish a variety of control objectives (position control, internal force control, constraints,and optimizations) for the generalized high-dimensional robotic systems (GHDRS) without restriction on target systems. Based on the concept of virtual decomposition by which a GHDRS is virtually decomposed into several objects and base-floating open chains, the motion control problem of the original system is converted into that of each object and that of each open chain, individually, while the internal force control as well as the constraint force control may be performed with respect to each object only. This feature makes it possible to implement the control algorithm of each subsystem in modularly structured hardware which can be integrated to form any specific robot controller dedicated to a specific application. In the sense of Lyapunov, it is declared that the dynamic coupling between every two physically connected subsystems can be completely represented by the so-called virtual power flows (VPFs) at the cutting points between them. Asymptotic stability of the complete system can be ensured by choosing the system Lyapunov function as the sum of all nonnegative accompanying functions assigned for the subsystems. Some possible applications based on the proposed approach are discussed. Finally, computer simulations of two PUMA 560 arms transporting a common object along a prespecified trajectory are carried out to verify the stability and robustness issues of the system.
99 citations
15 Jul 1997-Materials Science and Engineering A-structural Materials Properties Microstructure and Processing
TL;DR: In this paper, the preparation and characterization of metastable phases of the Al-Fe alloy system by mechanical alloying is reported, and the metastable disordered b.c. solid solution of Fe in Al (up to 1 at.% Fe) is formed.
Abstract: The preparation and characterization of metastable phases of the Al–Fe alloy system by mechanical alloying are reported. In Al-rich (up to 10 at.% Fe) alloys, the supersaturated f.c.c. solid solution of Fe in Al (up to 1 at.% Fe) is formed. Almost complete amorphization is confirmed in the composition range 17–33 at.% Fe. The metastable disordered b.c.c. solid solution of about 10 nm in grain size has also been formed by ball-milling for over 180 h in Fe-rich (above 50 at.% Fe) alloys. Examination of lattice parameter and magnetization have shown that the composition range and degree of disorder are comparable to those formed by crushing and sputter deposition.
91 citations
TL;DR: In this article, a thermal model based on the Dubinin-Radushkevich equation and thermodynamic analyses is given, which presents a complete and precise description of adsorption-desorption cycles.
81 citations
TL;DR: In this article, the authors show that active carbon fiber (ACF) might be a good substitute for activated carbon (AC) as the refrigeration capacity and adsorption time of ACF are three times more and 1/5 -1/10 of those of normal activated carbon, respectively.
Abstract: The experiments show that active carbon fiber (ACF) might be a good substitute for activated carbon (AC) as the refrigeration capacity Q{sub f} and adsorption time of ACF are three times more and 1/5--1/10 of those of normal activated carbon (AC), respectively. The COP for ACF-methanol could be 10% {approximately} 20% higher than that of AC-methanol. Thus ACF-methanol might be a good adsorption refrigeration pair for constructing adsorption refrigerators, especially those for household applications.
80 citations
TL;DR: In this paper, a new numerical approach for strongly nonlinear problems is proposed and applied to solve, as an example, a non-linear heat transfer problem, i.e., microwave heating of an unit plate, so as to verify its validity and great potential.
Abstract: In this paper, the Homotopy Analysis Method (HAM) proposed by Liao (1992a, 1992b, 1992c, 1992e, 1995a, 1997a) is greatly improved by introducing a nonzero variable ℏ. Based on the HAM, a new numerical approach for strongly non-linear problems is proposed and applied to solve, as an example, a non-linear heat transfer problem, i.e. microwave heating of an unit plate, so as to verify its validity and great potential. Our numerical experiments show that, by the proposed approach, iteration is not absolutely necessary for solving non-linear problems. This fact may deepen our understanding about numerical techniques for non-linear problems and widen our field of vision. Moreover, the basic ideas proposed in this paper may afford us a great possibility to greatly improve our current numerical techniques.
TL;DR: In this article, the Gibbs free energy as a function of temperature of the fcc(γ) and hcp(e) phases in the Fe-Mn-Si system is evaluated by the application of the general model for predicting thermodynamic properties for ternary systems from binary ones.
Abstract: The Gibbs free energy as a function of temperature of the fcc(γ) and hcp(e) phases in the Fe-Mn-Si system is evaluated by the application of the general model for predicting thermodynamic properties for ternary systems from binary ones, suggested by Chou and by the utilization of the available data from binary Fe-Mn, Fe-Si and Mn-Si systems and the SGTE DATA given by Dinsdale. The calculated result seems reasonable as compared with the experimental data.
TL;DR: In this paper, a large-scale gradient in the metal abundance has been detected with ASCA from an X-ray bright cluster of galaxies AWM7, where metal abundance shows a peak of 0.5 solar at the center and smoothly declines to <~ 0.2 solar at a radius of 500 kpc.
Abstract: A large-scale gradient in the metal abundance has been detected with ASCA from an X-ray bright cluster of galaxies AWM7. The metal abundance shows a peak of 0.5 solar at the center and smoothly declines to <~ 0.2 solar at a radius of 500 kpc. The gas temperature is found to be constant at 3.8 keV. The radial distribution of iron can be fit with a beta-model with beta ~ 0.8 assuming the same core radius (115 kpc) as that of the intracluster medium. The metal distribution in AWM7 suggests that the gas injected from galaxies is not efficiently mixed in the cluster space and traces the distribution of galaxies.
TL;DR: In this article, a large-scale gradient in the metal abundance has been detected with ASCA from an X-ray bright cluster of galaxies, AWM 7, showing that metal abundance shows a peak of 0.5 solar at the center and smoothly declines to 0.2 solar at a radius of 500 kpc.
Abstract: A large-scale gradient in the metal abundance has been detected with ASCA from an X-ray bright cluster of galaxies, AWM 7. The metal abundance shows a peak of 0.5 solar at the center and smoothly declines to 0.2 solar at a radius of 500 kpc. The gas temperature is found to be constant at 3.8 keV. The radial distribution of iron can be fitted with a β model with β ~ 0.8 assuming the same core radius (115 kpc) as that of the intracluster medium. The metal distribution in AWM 7 suggests that the gas injected from galaxies is not efficiently mixed in the cluster space and traces the distribution of galaxies.
TL;DR: In this article, the authors extend the knowledge of alloyed Ti{sub 5}Si{sub 3} compounds with Nb and Cr additions, and the discussion is focused on the alloying effect.
TL;DR: In this paper, the sliding wear resistance behavior of NiAl and SiC particles reinforced aluminum alloy matrix composites against S46C steel was studied and the sliding distance was 1000 m. Experiments were performed within a load range of 3.5 N to 82.7 N at constant sliding velocity of 0.15 m s 1.
TL;DR: Findings suggest than n-3 FAs reduce postprandial chylomicronemia in the rat by accelerating chylomaticron lipid clearance.
TL;DR: In this paper, the authors proposed to price an American option by approximating its early exercise boundary as a piecewise exponential function and showed that a three-point extrapolation scheme has the accuracy of an 800-time-step binomial tree, but about 130 times faster.
Abstract: This paper proposes to price an American option by approximating its early exercise boundary as a piece-wise exponential function. Closed-form formulas are obtained in terms of the bases and exponents of the piece-wise exponential function. It is demonstrated that a three-point extrapolation scheme has the accuracy of an 800-time-step binomial tree, but about 130 times faster. An intuitive argument is given to indicate why this seemingly crude approximation works so well. Our method is very simple and easy to implement. Comparisons with other leading competing methods are also included.
TL;DR: A general method for a homoclinic loop of planar Hamiltonian systems to bifurcate two or three limit cycles under perturbations is established in this article.
Abstract: A general method for a homoclinic loop of planar Hamiltonian systems to bifurcate two or three limit cycles under perturbations is established.Certain conditions are given under which the cyclicity of a homoclinic loop equals 1 or 2.As an application to quadratic systems,it is proved that the cyclicity of homoclinic loops of quadratic in-tegrable and non-Hamiltonian systems equals 2 except for one case.
TL;DR: In this article, the Hadamard product of matrices is used to obtain an explicit matrix formulation for the differential quadrature (DQ) and differential cubature (DC) solutions of nonlinear differential and integro-differential equations.
Abstract: This article points out that the differential quadrature (DQ) and differential cubature (DC) methods, due to their global domain property, are more efficient for nonlinear problems than the traditional numerical techniques such as finite element and finite difference methods. By introducing the Hadamard product of matrices, we obtain an explicit matrix formulation for the DQ and DC solutions of nonlinear differential and integro-differential equations. Due to its simplicity and flexibility, the present Hadamard product approach makes the DQ and DC methods much easier to use. Many studies on the Hadamard product can be fully exploited for the DQ and DC nonlinear computations. Furthermore, we first present the SJT product of matrixandvectortocomputeaccuratelyandefficientlytheFrechetderivativematrixintheNewton{Raphson method for the solution of the nonlinear formulations. We also propose a simple approach to simplify the DQ or DC formulations for some nonlinear differential operators and, thus, the computational efficiency of these methods is significantly improved. We give the matrix multiplication formulas to efficiently compute the weighting coefficient matrices of the DC method. The spherical harmonics are suggested as the test functionsintheDCmethodtohandlethenonlineardifferentialequationsoccurringinglobalandhemispheric weather forecasting problems. Some examples are analyzed to demonstrate the simplicity and efficiency of the presented techniques. It is emphasized that the innovations presented are applicable to the nonlinear computations of the other numerical methods as well. c 1997 John Wiley & Sons, Inc.
TL;DR: In this paper, a real-time error compensation system was developed to reduce the cutting force induced planar error of a two-axis turning center by using sensing, metrology, modeling, and computer control techniques.
Abstract: A real-time error compensation system has been developed to reduce the cutting force induced planar error of a two-axis turning center by using sensing, metrology, modeling, and computer control techniques. Ten error components are formulated as a two-dimensional error field. A piezoelectric force sensor mounted in the pocket under the tool turret is used to characterize the cutting forces. A compensation controller based on an IBM/PC has been linked with the existing computer numerical controller (CNC) to correct machine errors in real time. Three different types of cutting tests were performed and the results showed that the maximum diameter error in the workpiece was reduced by 67–85% using this compensation system.
07 Jul 1997
TL;DR: A concurrent computation model, chi calculus, in which communications resemble cut eliminations for classical proofs is investigated, and it is illustrated by showing that it incorporates the operational semantics of the call-by-name lambda calculus.
Abstract: The paper investigates a concurrent computation model, chi calculus, in which communications resemble cut eliminations for classical proofs. The algebraic properties of the model are studied. Its relationship to sequential computation is illustrated by showing that it incorporates the operational semantics of the call-by-name lambda calculus. Practically the model has pi calculus as a submodel.
TL;DR: In this paper, the generalized Almansi's theorem was employed to simplify the generalized second-order partial differential equations of the governing equations of piezoelectric materials. But the general solutions of these solutions are further simplified by employing a displacement function.
Abstract: First, on the basis of the governing equations of piezoelectric materials, a displacement function is introduced and the general solutions are derived. Second, by employing the generalized Almansi's theorem, these solutions are further simplified, i.e. all physical quantities are expressed in three displacement functions i (i = 1,2,3), which satisfy, respectively, three similar harmonic secondorder partial differential equations. Then the Green's functions for point forces and point charge acting in the interior of a twophase infinite piezoelectric plane are given using the method of mirror image source. The paper is concluded by a discussion of some special cases, in which the point force and charge solutions for an infinite uniform piezoelectric plane and for a halfplane with free or fixed straight boundary are given.
TL;DR: In this article, the general Boundary Element Method (BEM) was applied to solve a two-dimensional unsteady non-linear heat transfer problem in the time domain, governed by the hyperbolic heat conduction equation (HHCE) with the temperature-dependent thermal conductivity coefficients which are different in the x and y directions.
Abstract: The general Boundary Element Method (BEM) for strongly non-linear problems proposed by Liao (1995) is further applied to solve a two-dimensional unsteady non-linear heat transfer problem in the time domain, governed by the hyperbolic heat conduction equation (HHCE) with the temperature-dependent thermal conductivity coefficients which are different in the x and y directions. This paper confirms that the general BEM can be used to solve even those non-linear unsteady heat transfer problems whose governing equations do not contain any linear terms in spatial domain.
TL;DR: In this article, an efficient approach to the analysis of non-stationary random responses of structures subjected to evolutionary random excitation is proposed, which is first transformed into a pseudo excitation to generate deterministic equations of motion, which are then solved by means of a modified high precision direct integration method.
TL;DR: In this paper, two cast nickel-base superalloys with superior creep rupture life at high temperatures and high stresses were developed and the microstructural characteristics of γ-precipitates and the hardening behavior were studied by electron microscopy and micro-hardness testing.
Abstract: Two cast nickel-base superalloys with superior creep rupture lives at high temperatures and high stresses were developed. In the present study, the microstructural characteristics of γ′-precipitates and the hardening behaviour were studied by electron microscopy and micro-hardness testing. The alloys were solution-treated at 1553 K for 2 h and air-cooled followed by step ageing heat treatments. Ageing up to 300 h at 1143, 1223 and 1293 K was carried out to examine the effects of ageing temperature and ageing time on the growth of γ′-precipitates. The growth kinetics of γ′-precipitates was analysed. The experimental evidence reveals that the morphology of γ′ does not change in shape during heat treatments. The γ′ is usually cubic in both Alloy B and Alloy C. Growth of γ′ precipitates proceeds by Ostwald ripening controlled by volume diffusion of solute atoms despite the high volume fraction of γ′ and complex compositions in these two alloys. The activation energies for the growth are evaluated as 272 and 277 kJ mol-1 for Alloy B and Alloy C, respectively, which correlate well to coarsening of γ′ in other commercial and developed superalloys. The hardness increases to a peak value at about 20 to 60 h for Alloy B and at about 10 to 20 h for Alloy C during ageing. The hardness of the alloys hardly decreases and still maintains a high value at high temperatures after passing the hardness peak.
TL;DR: Results verify that HIFU has the power to ablate liver tumour quite adequately and accurately, and that sonography is useful for monitoring sonoablated liver tumours.
Abstract: This project aimed to determine the adequacy and accuracy of high-intensity focused ultrasound (HIFU) for ablating experimental liver tumour, and to assess imaging methods for monitoring the therapeutic results. The rabbit liver pseudotumour model was established by injection of Freund's complete adjuvant into the liver; the animals then received HIFU therapy via laparotomy at the focal point of the beam (1.1 MHz, 500 W/cm2, 20 s). The rabbits were sacrificed at scheduled times after treatment and liver tumours were examined histologically. Sequential imaging of the liver tumour was performed before and after HIFU treatment. HIFU accurately destroyed the rabbit liver tumour and induced coagulation necrosis 24 h later. Sonographic imaging studies revealed that characteristic changes occurred. A hyperechoic mass turned to a hypoechoic lesion with no Doppler signal, and a high echogenic rim appeared 24 h after HIFU treatment, correlating well with the pathological changes of a sonoablated lesion. These results verify that HIFU has the power to ablate liver tumour quite adequately and accurately, and that sonography is useful for monitoring sonoablated liver tumour.
TL;DR: In this article, a thermal postbuckling analysis for a stiffened laminated cylindrical shell of finite length subjected to a uniform or non-uniform parabolic temperature distribution varying in the circumferential or axial direction is presented.
Abstract: A thermal postbuckling analysis is presented for a stiffened laminated cylindrical shell of finite length subjected to a uniform or non-uniform parabolic temperature distribution varying in the circumferential or axial direction. The formulations are based on a boundary layer theory of shell buckling which includes the effects of non-linear prebuckling deformations, non-linear large deflections in the postbuckling range, and initial geometrical imperfections of the shell. The “smeared stiffener” approach is adopted for the stiffeners. The analysis uses a singular perturbation technique to determine thermal buckling loads and postbuckling equilibrium paths. Numerical examples are presented that relate to the performances of perfect and imperfect, stiffened and unstiffened cross-ply laminated cylindrical shells. Typical results are presented in dimensionless graphical form and exhibit two different types of thermal postbuckling response.
TL;DR: A new design method for neural networks is presented based on evolutionary programming, which is extended to design recurrent neural networks through introducing ‘delayed links’ into networks.
TL;DR: A method based on the wavelet transform to calculate the irregularity of the QRS complex, which may relate to inotropy, is successfully extracted from original ECG signals and provides a new approach to studies of ECG dynamics.
Abstract: How to extract information intensively from ECGs for the diagnosis of cardiovascular diseases and assessment of heart function is a topical subject. Using a method based on the wavelet transform to calculate the irregularity of the QRS complex, which may relate to inotropy, the QRS complex irregularity time series is successfully extracted from original ECG signals. This provides a new approach to studies of ECG dynamics. With the help of non-linear dynamics theory, the QRS complex irregularity time series of eight subjects, from the MIT/BIH arrhythmia database are studied qualitatively and quantitatively, and the characteristics of ECG dynamics are analysed extensively. The power spectrum, phase portrait, correlation dimension, largest Lyapunov exponent, time-dependent divergence exponent and complexity measure all verify the fact that ECG dynamics are dominated by an underiying 5–6-dimensional non-linear chaotic system, whose complexity measure is about 0.7. The QRS complex irregularity time series contains abundant information about all parts of the heart and the regulation of the autonomic nervous system, and so further analyses are of great potential theoretical and clinical significance to patho-physiology studies and ambulatory monitoring.