Showing papers by "Shanghai Jiao Tong University published in 1990"
TL;DR: The character tables of the association schemes obtained from the actions of finite (simple) orthogonal groups are studied to show that they are controlled by the character table of the group PSL (2, q).
45 citations
TL;DR: In this paper, a semi-analytical method is used to determine the local joint flexibility of tubular joints of offshore structures and a series of K joints with symmetric configuration is calculated.
34 citations
01 May 1990
TL;DR: The interactive step tradeoff method (ISTM) is composed of three basic steps: an efficient solution and the corresponding local tradeoff information are provided by the analyst, and the decision maker determines the preference direction and step size.
Abstract: The interactive step tradeoff method (ISTM) is composed of three basic steps. First, an efficient solution and the corresponding local tradeoff information are provided by the analyst. Then, the decision maker determines the preference direction and step size. Again the analyst looks for a new efficient solution according to the preference information; the new solution should dominate the previous one. In ISTM, the efficient solution and the local tradeoff information, the current values of objective functions, and the tradeoff rates between them are obtained by solving an auxiliary problem. The auxiliary problem is defined, and relationships between the optimal solutions of the auxiliary problem and the efficient solutions of the original problem are explored. The relationships between the Kuhn-Tucker multipliers (or simplex multipliers) of the auxiliary problems and the tradeoff rates are analyzed. The particular steps of the ISTM algorithm are given. An example is discussed to illustrate the use of the algorithm. >
33 citations
TL;DR: Saturation dislocation configurations of AISI-310 stainless steel cyclically deformed at constant plastic strain amplitudes (e pl ) in the range 1 × 10 −4 −9 × 10−3 are investigated with transmission electron microscopy (TEM).
Abstract: Saturation dislocation configurations of AISI-310 stainless steel cyclically deformed at constant plastic strain amplitudes (e pl ) in the range 1 × 10 −4 –9 × 10 −3 are investigated with transmission electron microscopy (TEM). At low e pl range, dislocations are generated in many slip systems and distributed more or less uniformly. At intermediate e pl range, various dislocation structures, such as dislocation bundles, veins or {110} walls, form. Different structures may be distributed in separate layers with boundaries parallel to {111} at the up part of this e pl range. When e pl ⩾ 6 × 10 −3 , {100} labyrinth walls and misoriented dislocation cells form. The dislocation configurations found at low e pl cases are also developed in some areas of the specimens deformed at high e pl . The three e pl ranges of different characteristics of saturation dislocation configurations coincide well with the three regimes of different cyclic behaviours of this material reported in Part I [ Acta metall. mater. 38 , 2135 (1990)].
26 citations
TL;DR: In this article, the buckling and postbuckling behaviors of perfect and imperfect antisymmetrically angle-ply laminated composite plates under uniaxial compression were studied by perturbation technique which takes deflection as its perturbance parameter.
Abstract: The buckling and postbuckling behaviors of perfect and imperfect antisymmetrically angle-ply laminated composite plates under uniaxial compression have been studied by perturbation technique which takes deflection as its perturbation parameter.
21 citations
TL;DR: In this paper, a blind image restoration algorithm for noiseless blurred two-tone images based on the criterion of minimum entropy is presented, and performance of the algorithm is demonstrated by simulation.
Abstract: A blind image restoration algorithm for noiseless blurred two-tone images based on the criterion of minimum entropy is presented. Performance of the algorithm is demonstrated by simulation.
19 citations
TL;DR: In this paper, the basic differential equations for finite deflections of elastic plates according to Reissner's approximate stress distributions are given and the buckling and postbuckling problems of elastic rectangular plates, including the effect of transverse shear deformation, are solved and discussed.
Abstract: This paper gives the basic differential equations for finite deflections of elastic plates according to Reissner's approximate stress distributions. The buckling and postbuckling problems of elastic rectangular plates, including the effect of transverse shear deformation, are solved and discussed, by using perturbation method suggested in ref. [8]. The postbuckling equilibrium paths of perfect and imperfect moderately thick rectangular plates are presented and compared with the results based on thin plate theory.
16 citations
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TL;DR: In this paper, the authors show that the formation of bainite by a shear mechanism is thermodynamically impossible, and they also show that at temperatures nearMs, as the driving force will be large enough, the growth of Bainsite by shear may be able to occur, and evidence is given by the morphology of bainsite showing shear characteristic.
Abstract: Driving force calculations for Fe-C, Fe-X-C, and Cu-Zn alloys show that the formation of bainite by a shear mechanism is thermodynamically impossible. There exist superledges on the broad faces of bainite in steels, revealing that the thickening of bainite probably proceeds by a ledge mechanism. In some Fe-Ni-C alloys and commercial steels, no simple relationship was found between the strength of austenite and theBs temperature; however, there is a linear relationship betweenBs and the diffusion coefficient of carbon and iron in austenite, as well as between the incubation period and the function containing DFeγ. The bainite reaction seems to be controlled by diffusional processes. In a low-carbon Ni-Cr steel, the morphology of the bainite/matrix interface boundary is different from that of the martensite, and the habit plane of the bainite (1 7 11)α deviates 13.3 deg from that of the martensite (1 1 0)α, indicating that the mechanism of the bainite reaction is not necessarily analogous to that of the martensitic transformation. At temperatures nearMs, as the driving force will be large enough, the growth of bainite by shear may be able to occur, and evidence is given by the morphology of bainite showing shear characteristic. X-ray diffraction study in Ag-Cd and internal friction measurements in Ag-Cd and Cu-Zn-Al alloys, 18CrNiWA steel, and its decarburized specimen reveal that the nucleation process occurs within the incubation period of bainite formation.
15 citations
15 Aug 1990-Materials Science and Engineering A-structural Materials Properties Microstructure and Processing
TL;DR: In this paper, the dislocation behavior during the plastic deformation of directionally solidified Rene 80 has been studied by transmission electron microscopy, and a mechanism for secondary stage creep has been proposed, and the dependence of the secondary creep rate ϵ on the cube edge length a and volume fraction νf of cubic γ′ precipitates has been found to be ϵ ∝ a ν f 2 3.
Abstract: The dislocation behaviour during the plastic deformation of directionally solidified Rene 80 has been studied by transmission electron microscopy. In tensile deformation, γ′ shearing occurs by the slip of antiphase boundary (APB)-coupled 1 2 〈110〉 dislocation pairs on {111} planes and then cross-slip to {100} planes to act as obstacles to moving dislocations at temperatures below the peak temperature, and by the viscous slip of two super-lattice intrinsic stacking fault (SISF)-separated 1 3 〈112〉 superpartials whose cores have split on {111} planes at temperatures above the peak temperature. In creep deformation, γ′ shearing occurs again by viscous slip of two SISF-separated 1 3 〈112〉 superpartials with unsplit cores on {111} planes and/or by slip of APB-coupled 1 2 〈110〉 dislocation pairs on {111} planes. However, climbing of dislocations at γ-γ′ interfaces also occurs at 760 °C under a stress of 618 MPa and at 980 °C under a stress of 190 MPa. According to the climbing model, a mechanism for secondary stage creep has been proposed, and the dependence of the secondary creep rate ϵ on the cube edge length a and volume fraction νf of cubic γ′ precipitates has been found to be ϵ ∝ a ν f 2 3 .
15 citations
TL;DR: In this paper, an improved method based on Kokawa's approach was proposed for fault location in large-scale chemical plants, where a frame system was used to describe the failure propagation network in detail.
14 citations
TL;DR: Extraction chromatography by which 99.99% pure scandium oxide can be prepared from starting material containing about 70% scandiam oxide has been developed by taking advantage of some peculiar properties of complexation and extraction chemistry.
TL;DR: The squeezed-polaron theory are shown to be better than those of the ordinary polaron theory and a continuous phase transition is found between the long-range CDW ordering state and the short-range antiferromagnetic correlated state with a transition point different from the prediction of the Hartree-Fock decoupling.
Abstract: The effect of quantum lattice fluctuations is investigated in a half-filled one-dimensional Peierls-Hubbard model. The nonadiabatic effects due to finite phonon frequency \ensuremath{\omega} are treated by introducing the polaronic transformation and the squeezed-phonon state. The electronic correlations are treated by means of a modified Gutzwiller approach and a unified description for the long-range charge-density-wave (CDW) ordering state and the short-range antiferromagnetic correlated state has been developed. The main result is a rather good description of the continuous variation of the dimerization as functions of the Hubbard U and \ensuremath{\omega} is given, which is in good agreement with that of the numerical simulations. The results of the squeezed-polaron theory are shown to be better than those of the ordinary polaron theory. A continuous phase transition is found between the long-range CDW ordering state and the short-range antiferromagnetic correlated state with a transition point different from the prediction of the Hartree-Fock decoupling. The effect of quantum lattice fluctuations on the transition point is also discussed.
TL;DR: In this paper, a multi-Gaussian function model is proposed for deconvoluting directly the Tung equation for instrumental band broadening (column dispersion) in gel-permeation chromatography using the Fourier transform technique.
TL;DR: A valence-bonding state is proposed for describing the short-range antiferromagnetic correlation for intermediate values of {ital U} and {ital V} and the transition point between the VB state and the CDW state is determined, which is in good agreement with that of the numerical simulations.
Abstract: The effect of quantum lattice fluctuations on the ground state of a half-filled-band one-dimensional molecular-crystal model with on-site ({ital U}) and nearest-neighbor ({ital V}) Coulomb repulsion is investigated. The nonadiabatic effects due to finite phonon frequency {omega} are treated through a variational polaron wave function. The electronic correlations are decoupled by a Hartree-Fock approximation. Our variational approach gives a rather good description of the continuous variation of the dimerization, which is in good agreement with that of the Monte Carlo simulations, as functions of {ital U}, {ital V}, and {omega}. However, the Hartree-Fock theory predicts a fictitious long-range spin-density-wave order and a discontinuous transition between it and the charge-density-wave (CDW) state. These are somewhat different from the results of numerical simulations. Furthermore, we propose a valence-bonding (VB) state for describing the short-range antiferromagnetic correlation for intermediate values of {ital U} and {ital V} and determine the transition point between the VB state and the CDW state, which is in good agreement with that of the numerical simulations. The effect of quantum lattice fluctuations on the transition point is also discussed.
TL;DR: A method for calculating the time-specific reliability characteristics of a noncoherent system directly, using the disjoint cut-set approach is presented.
Abstract: A method for calculating the time-specific reliability characteristics of a noncoherent system directly, using the disjoint cut-set approach is presented. It is assumed that the system and elements have two states, good or failed; only one element can change its state at one time; and the states of elements are mutually s-independent. >
TL;DR: In this article, a new variational ground state, the displaced-squeezed-state, was proposed for the linear E-e Jahn-Teller system, which favors a larger displacement of the wave function of the vibrational mode.
TL;DR: In this article, the cyclic responses of AISI-310 austenitic stainless steel with coarse grains were investigated in the plastic strain amplitude (e pl ) range 1 × 10 −4 −9 × 10−3.
Abstract: Cyclic responses of AISI-310 austenitic stainless steel with coarse grains are investigated in the plastic strain amplitude (e pl ) range 1 × 10 −4 –9 × 10 −3 . With respect to the cyclic hardening behaviour, three ranges of e pl may be distinguished. e pl −4 : neither cyclic hardening nor cyclic softening is observed; 8 × 10 −4 pl −3 : a cyclic softening follows a cyclic hardening before the saturation is approached; e pl > 8 × 10 −3 : a cyclic hardening leads directly to saturation. The cyclic stress-strain (CSS) curve exhibits three regimes of strain dependence of saturation stress (σ s ): in regime I, σ s increases almost unnoticeably with increasing e pl ; in regime II, σ s increases smoothly with increasing e pl ; in regime III, σ s increases dramatically with increasing e pl . The three regimes of the CSS curve fall into line with the different ranges of e pl of different cyclic hardening behaviours.
01 Jan 1990
TL;DR: In this paper, a perturbation technique for the buckling and postbuckling of rectangular plates under inplane compression has been proposed, which takes deflection as its perturbance parameter.
Abstract: Full-range analysis for the buckling and postbuckling of rectangular plates under inplane compression has been made by perturbation technique which takes deflection as its perturbation parameter.
01 Jan 1990
TL;DR: In this paper, the effect of A14C3 formation at the fiber/matrix interface on the properties of carbon fiber reinforced aluminum alloy matrix composites has been the subject of numerous investigations.
Abstract: The effect of A14C3 formation at the fiber/matrix interface on the properties of carbon fiber reinforced aluminum alloy matrix composites has been the subject of numerous investigations. However, there are other phases found at the interface between carbon fibers and the matrix that are not reaction products between the carbon fiber and the matrix and may have equally important effects on the mechanical properties of composites. This paper deals with the microstructure of a number of Al base alloy systems that are expected to be commercially significant. We examined composite castings manufactured by state-of-the-art pressure infiltration techniques where the important casting parameters are independently controlled. The composite systems investigated were P-55 reinforced A1100, A357, Al4.5%Cu, and A1-0.35%Ti matrix alloys. These composite castings were examined by Transmission Electron Microscopy (TEM). In addition to A14C3, phases such as CuAl2, Si and A13Ti specific to the matrix alloy system were observed at the interface and in interfiber regions of the composite casting. The microstructures of these intermetallics are strongly influenced by the choice of processing parameters such as the liquid metal temperature, Tm, the preform temperature, Tp, and the solidification time. In the case of the Ti containing alloy, extremely fine grain sizes, on the order of 0.4 µm, were observed in the ,interfiber regions. These microstructures are related to the mechanical properties of the composites and of fibers leached from composite castings obtained during other phases of this study.
TL;DR: In this article, the effects of the notch position and weld metal matching on the HAZ toughness were studied by taking weld metals with three strength levels (austenitic, ferritic and martensitic weld metals).
Abstract: HAZ CTOD tests were carried out on nonmatching bead on plate SAW weldments at room temperature. The effects of the notch position and weld metal matching on the HAZ toughness were studied by taking weld metals with three strength levels (austenitic, ferritic and martensitic weld metals). The notches were located parallel (L-type) and perpendicular (T-type) to the straight fusion line and across the beveled fusion line (cross-bond type). The results indicate the T-type CTOD specimens may be used for screening the most brittle zone of the HAZ and may to a certain extent ease the experimental difficulties of the HAZ CTOD testing. The CTOD crack initiation (pop-in) values are controlled by the microstructure of the crack tip zone and the strength of the adjacent material. The recently proposed pop-in assessment procedure was used for the evaluation of the pop-ins and results were discussed in terms of the measurements of the load drop, crack extension and the CTODjump values.
TL;DR: In this paper, a ring structure of self-focusing light field was observed, which was attributed to the intrinsic refractive index profile of the fiber used in the experiment, and numerical calculation was carried out based on a square profile-ring-shaped local waveguide model.
01 Jan 1990
TL;DR: In this paper, the authors investigated the transient heat transfer from thin superconducting and normal wires to saturated Hell and to pressurized Hell by applying rectangular current pulses of 0.5 milliseconds duration and longer.
Abstract: Transient heat transfer from thin superconducting and normal wires to saturated Hell and to pressurized Hell was investigated. Rectangular current pulses of 0.5 milliseconds duration and longer were applied to the sample while voltage and current were detected with a resolution in the microsecond range. For the determination of the sample temperature the temperature characteristic of the wire resistivity was used in the case of normal conductors and the temperature characteristic of the critical current in the case of superconductors. Data are reported for bath temperatures of 2 K and, in the case of the superconducting samples, transverse magnetic fields of 1.5 T.
TL;DR: These two methods for job scheduling in parallel computer systems have the advantages of lower real time scheduling overhead, less context switching, less communication delay and providing deadlock prevention.
01 Sep 1990
TL;DR: In this paper, a new approach for optical flow (image velocity) fields computation using computational neural networks is presented, which consists of three stages: estimation of the parameters of the neural network model, dynamic measurement of the perpendicular velocity components of the contours or region boundaries and computation of the image velocity fields.
Abstract: A new approach for optical flow (image velocity) fields computation is presented using computational neural networks. The computational procedure consists of three stages: estimation of the parameters of the neural network model, dynamic measurement of the perpendicular velocity components of the contours or region boundaries and computation of the image velocity fields. The parameters are estimated by comparing the energy function of the neural network with a constrained error function. The nonlinear velocity fields computation method is then carried out iteratively by using a dynamic algorithm to minimise the energy function simultaneously with the dynamic measurement of the perpendicular velocity components by a dynamic procedure. Experiments generate velocity fields that are meaningful and consistent with visual perception.
TL;DR: The use of refined methodology, such as isoelectrofocusing (IEF), cation exchange high performance liquid chromatography (HPLC), and reversed phase HPLC, as procedures for testing for the possible presence of hemoglobin (Hb) abnormalities has recently led to the detection of several new variants.
Abstract: The use of refined methodology, such as isoelectrofocusing (IEF), cation exchange high performance liquid chromatography (HPLC), and reversed phase HPLC, as procedures for testing for the possible presence of hemoglobin (Hb) abnormalities has recently led to the detection of several new variants. This was again the case with Hb Zengcheng which was observed when a large batch of cord blood samples from Chinese newborns was tested by IEF and reversed phase HPLC
TL;DR: In this paper, a new method for evaluating practical values of the PV factor for piston rings is proposed, and a parameter in terms of the temperature difference is introduced which describes the interfacial thermal effects.
11 Jun 1990
TL;DR: A new mathematical model of solving the stable performance of gas turbine engines is proposed, which has the features of not only being suitable for inverse algorithm for turbine performance, but also having less dimensions than existing models.
Abstract: This paper points out that the turbine performance computation method used widely at present in solving the performance of gas turbine engines is a numerically instable algorithm. So a new method, namely inverse algorithm, is proposed.This paper then further proposes a new mathematical model of solving the stable performance of gas turbine engines. It has the features of not only being suitable for inverse algorithm for turbine performance, but also having less dimensions than existing models. So it has the advantages of high accuracy, rapid convergence, good stability, less computations, and so forth. It has been fully proven that the accuracy of the new model is much greater than that of the common model for gas turbine engines. Additionally, the time consumed for solving the new model is approximately 1 / 4 ∼ 1 / 10 of that for the common model. Therefore, it is valuable in practice.Copyright © 1990 by ASME
TL;DR: By using the matched asymptotic expansion method and the idea of edge layer, a mathematic model for describing the interaction between weakly nonlinear shallow-water waves and three-dimensional floating bodies is formed in this paper.
Abstract: By using the matched asymptotic expansion method and the idea of edge layer, a mathematic model for describing the interaction between weakly nonlinear shallow-water waves and three-dimensional floating bodies is formed in the paper. As a numerical example, the diffraction of a solitary wave around a vertically floating circular cylinder has been investigated and the results are presented. The present method can further be extended to the study of wave diffraction around floating bodies of general shape.