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Showing papers by "Harbin Institute of Technology published in 1998"


Journal ArticleDOI
TL;DR: In this paper, the distributions of residual stresses of shot peened 20Cr, 30CrMo, 40Cr, GC4, 45 steels and LC9 aluminum alloy over the hardened layer were measured in an X-ray diffraction apparatus using the 0 and 30° two-point method with step-by-step electrolytical dissolution, and then studied quantitatively.

218 citations


Journal ArticleDOI
TL;DR: In this paper, the effect of pore size of the membrane, transmembrane pressure and volumetric ratio of oil phase to internal aqueous phase in the emulsion on demulsification was investigated.

128 citations


Journal ArticleDOI
TL;DR: The operation principle of the linear motor is demonstrated and a prototype linear ultrasonic motor of 40 mm in length, 10 mm in width is fabricated and investigated and the following performances have been achieved: maximum speed 200 mm/s, maximum force output 150 gf, and resolution less than 0.1 microm.
Abstract: A standing wave bi-directional linearly moving ultrasonic motor has been studied for the purpose of implementing a practical linear ultrasonic motor with simple structure, simple driving and high resolution. The fundamental principle of this linear motor is projections on the right sides of a standing wave crests generating thrust force right-diagonally on the slider pressed against the projections. Correspondingly, projections on the left sides of the wave crests make the slider move toward the left. In order to realize bi-directional actuating, vibration mode B3 or B4 is excited in a rectangular plate-type vibrator to make the projections on the right sides or the left sides of the wave crests. In this paper, the operation principle of the linear motor is demonstrated. Furthermore, a prototype linear ultrasonic motor of 40 mm in length, 10 mm in width is fabricated and investigated. The following performances have been achieved: maximum speed 200 mm/s, maximum force output 150 gf, and resolution less than 0.1 /spl mu/m.

117 citations


Journal ArticleDOI
TL;DR: This paper deals with the Cauchy problem of fuzzy differential equations, and the existence theorems under compactness-type conditions are obtained.

108 citations


Journal ArticleDOI
TL;DR: In this article, a data-driven method of joint inversion of well-log and seismic data, based on the power of adaptive mapping of artificial neural networks (ANNs), is presented.
Abstract: We present a data‐driven method of joint inversion of well‐log and seismic data, based on the power of adaptive mapping of artificial neural networks (ANNs). We use the ANN technique to find and approximate the inversion operator guided by the data set consisting of well data and seismic recordings near the wells. Then we directly map seismic recordings to well parameters, trace by trace, to extrapolate the wide‐band profiles of these parameters using the approximation operator. Compared to traditional inversions, which are based on a few prior theoretical operators, our inversion is novel because (1) it inverts for multiple parameters and (2) it is nonlinear with a high degree of complexity. We first test our algorithm with synthetic data and analyze its sensitivity and robustness. We then invert real data to obtain two extrapolation profiles of sonic log (DT) and shale content (SH), the latter a unique parameter of the inversion and significant for the detailed evaluation of stratigraphic traps. The hig...

75 citations


Journal ArticleDOI
TL;DR: In this paper, the influence of natural ageing on the overall subsequent precipitation processes of two Al-Mg-Si alloys has been studied by a series of differential scanning calorimeter (DSC) analyses.

73 citations


Journal ArticleDOI
TL;DR: Fuzziness existing in the process of generating decision trees by discretizing continuous-valued attributes is considered and a better way to express this fuzziness via fuzzy numbers is presented using possibility theory.

61 citations


Journal ArticleDOI
TL;DR: In this article, an analytical model was developed to study the influence of thermal residual stresses on the elastic and yield behaviors of aligned short fiber-reinforced metal matrix composites.
Abstract: An analytical model was developed to study the influence of thermal residual stresses on the elastic and yield behaviors of aligned short fiber-reinforced metal matrix composites. Three-dimensional solutions of elastic stress field in the matrix of a circular cylindrical unit cell were first obtained based on the theory of elasticity. On this basis, an alternative analysis of the stress transfers between the matrix and the fiber was given by using the shear lag analysis, which provides the expressions for the stress distributions in the matrix and the fiber. The thermal residual stresses and the distributions of the stresses under tensile and compressive loadings as a function of the material parameters, such as fiber volume fraction, fiber aspect ratio and matrix yield stress, were calculated. Furthermore, simple expressions for the composite elastic modulus and yield strength under tensile and compressive loadings were derived. These expressions were used to study the influence of the thermal residual stresses and the material parameters on the elastic moduli and yield strengths under tensile and compressive loadings. Finally, the model predictions were compared with the experimental results on the SiCw/Al–Li T6 composite and several SiCw/Al T6 composites in literature and also with the other theoretical models.

60 citations


Journal ArticleDOI
TL;DR: In this paper, the fatigue limits of shot peened 20Cr, 30CrMo, 40Cr, GC4, 45 steels and Al-alloy LC9 have been studied quantitatively.

60 citations


Journal ArticleDOI
TL;DR: In this article, a Cu-38%Zn alloy has been deformed to large strain by a new method, and the change of structure has been investigated, which is called equal-channel angular pressing (ECAP).
Abstract: A Cu–38%Zn alloy has been deformed to large strain by a new method, and the change of structure has been investigated. The method is called equal-channel angular pressing (ECAP). After deformation, the microstructure has been changed greatly, while the macrostructure, such as the size and distribution of the second phase and the original grain boundaries have been changed a little. As the equivalent true strain is increased to 10, the average crystallite size is decreased to 0.4 μm according to transmission electron microscopy (TEM) observation and X-ray diffraction results. At the same time, the Vickers hardness is increased from 71 to 220.

52 citations



Proceedings ArticleDOI
Wu jiangqin1, Gao wen, Song yibo, Liu wei, Pang bo 
12 Oct 1998
TL;DR: In this paper the process of building a simple word-level sign language recognition system is presented, and the method for recognizing sign language words is also proposed.
Abstract: Human beings usually interact with each other either by via a natural language channel such as speech and writing, or by body languag, e.g. hand gestures, head gestures, facial expression, lip motion and so on. As a part of natural language understanding, sign language recognition is very important. On one hand, it is one of the main methods of human-computer interaction in virtual reality; on the other hand, it is an auxiliary tool for a deaf-mute to communicate with ordinary people through computer. In this paper the process of building a simple word-level sign language recognition system is presented, and the method for recognizing sign language words is also proposed.

Journal ArticleDOI
TL;DR: The results demonstrated that space radiation environment could induce inheritable mutagenic effects on plant seeds, and verified the change in genetic material in the mutants.

Journal ArticleDOI
TL;DR: It is shown that the entire set of all Hurwitz-stable matrices of order n is the product of two convex open cones and itself forms a simply connected open cone in the parameter space with a vertex at the origin.

Journal ArticleDOI
TL;DR: In this article, a method that estimates mass and stiffness matrices of shear building from modal test data is presented, which depends on only measurable points that are less in number than the total structural degrees of freedom, and on the first two orders of structural mode measured.
Abstract: A method that estimates mass and stiffness matrices of shear building from modal test data is presented in this paper. The method depends on only measurable points that are less in number than the total structural degrees of freedom, and on the first two orders of structural mode measured. So it is applicable to most of the general test. Based on this method modal data of unmeasurable points are estimated, then global mass and stiffness matrices of structure are obtained by using the first two orders of modal data. Taking advantage of iteration the optimum global mass and stiffness matrices are gained. Finally, an example is studied in this paper. Its result shows that this method is reliable. © 1998 John Wiley & Sons, Ltd.

Journal ArticleDOI
TL;DR: By introducing a pre-whitening procedure in multiple signal classification (MUSIC), the resolution performance of MUSIC is enhanced in spatially colored noise environment and a post-processing method is proposed to eliminate the sidelobe of spatial spectrum arising from the estimation errors of a noise covariance matrix.
Abstract: Owing to the decametric wavelength, the angular resolution of high-frequency surface wave radar (HFSWR) is usually coarse, especially when dimensions of antenna arrays are restricted such as in shipborne HFSWR applications. In this paper, the relative strength of atmospheric noise and sea clutter that will heavily degrade the capabilities of HFSWR in target detection and resolution are calculated, then a method for estimating the spatial covariance matrix of background noise is presented. By introducing a pre-whitening procedure in multiple signal classification (MUSIC), the resolution performance of MUSIC is enhanced in spatially colored noise environment. Results with data from the aircraft detecting experiment conducted by the Research Institute of Electronic Engineering of Harbin Institute of Technology in 1994 and simulated data of two targets show that pre-whitened MUSIC can provide a better resolution and accurate determination of target number. Furthermore, a post-processing method is proposed to eliminate the sidelobe of spatial spectrum arising from the estimation errors of a noise covariance matrix.

Journal ArticleDOI
TL;DR: Zheng, YF (reprint author), Chinese Acad Sci, Atom Imaging Solids Lab, Inst Met Res, Shenyang 110015, Peoples R China Harbin Inst Technol, Sch Mat Sci & Engn, Harbin 150001, People R China;

Journal ArticleDOI
01 Jan 1998-Wear
TL;DR: In this article, the interface adhesion behavior between the cutter and work piece when austenitic stainless steel is milled by a cemented carbide cutter is described, and it is shown that at medium cutting speed, adhering layer is formed between the rake face and the chip.

Journal ArticleDOI
TL;DR: The new extended stochastic high-level evaluation Petri nets (ESHLEP-N) are presented which are more suitable for modelling and simulation of flexible manufacturing systems (FMSs) and the scheduling and simulation expert system for the FMS is designed and established.
Abstract: The present paper presents the new extended stochastic high-level evaluation Petri nets (ESHLEP-N) which are more suitable for modelling and simulation of flexible manufacturing systems (FMSs). The advantages of ESHLEP-N lie in the fact that their resulting models are not only simpler, more intuitive and more descriptive, but also of the more inferential and decisive power. Based on the ESHLEP-N model, the scheduling and simulation expert system (ES) for the FMS is designed and established. With the help of the ES, we will put forward some new dynamic-rescheduling rules aiming at reducing no-inputs and blockings. The simulations show that the throughputs of the rescheduling can increase on an average by 6.48% as compared with those of the non-rescheduling. The comparison between the experiment on the real FMS and the simulation on the ES indicates that the ES is effective.

Proceedings ArticleDOI
01 Sep 1998
TL;DR: In this paper, a parametrisation for the Luenberger observer is proposed for robust fault detection in multivariable linear systems with unknown disturbances, and the effect of the unknown disturbance is decoupled from the residual signal.
Abstract: Considers, using the Luenberger observer, the problem of robust fault detection in multivariable linear systems with unknown disturbances. The approach is based on a proposed parametrisation for the Luenberger observer. By properly constraining the design parameters, the effect of the unknown disturbance is decoupled from the residual signal. An example illustrates the effect of the proposed approach.

Journal ArticleDOI
TL;DR: The model-free learning adaptive control (MFLAC) based on new concepts called pseudo-gradient (PG) for a class of non linear systems is presented, and the stability of the regulator and the robustness of the schemes is discussed.

Journal ArticleDOI
TL;DR: In this article, the substructure of martensite in the Ti,Ni,Hf, alloy has been investigated by high-resolution electron microscopy (HREM) and discussed within the framework of a phenomenological theoretical analysis.


Journal ArticleDOI
TL;DR: In this article, a three dimensions of semivectorial finite difference beam propagation method (FD-BPM) in cylindrical coordinates is investigated in order to analyze the optical wave propagation in the bent waveguides with the strong lateral confinement which will keep low radiation loss.
Abstract: A three dimensions of semivectorial finite difference beam propagation method (FD-BPM) in cylindrical coordinates is investigated in order to analyze the optical wave propagation in the bent waveguides with the strong lateral confinement which will keep low radiation loss. The three dimensional (3D) semivectorial wave propagation equation is programmed in the quick and unconditionally stable procedure by using the alternating direction implicit method. This version of FD-BPM could well express the polarization characteristics of modal field near the dielectric interfaces and accurately simulate the wave propagation in bent waveguides even at a very small radius (<100 /spl mu/m). Moreover, it is pointed out that the numerical precision of the algorithm is intensively affected by the propagation loss of bent waveguides along with the propagation step length of beam propagation method.

Journal ArticleDOI
TL;DR: In this paper, the distribution of the displacements in different sections of the blank for backward tube spinning has been obtained by elasto-plastic finite-element simulation, revealing the characteristics of metal flow on backward spinning and provide a theoretical basis for controlling the dimensional precision and improving the quality of spun parts in practical production.

Journal ArticleDOI
TL;DR: In this paper, the authors investigated the crystallization process of amorphous Zr75Cu27Al8 alloy, both from ammorphous state and supercooled liquid, and found that the activation energy is much higher in the transition from amomorphous state than that from super cooled liquid, mainly controlled by the growth of pre-existing quenched-in 3D nuclei with a constant growth rate.

Journal ArticleDOI
TL;DR: A β-ray on-line monitoring technique, capable of measuring the resin content conveniently, quickly and accurately has been developed in this paper, which is used in the manufacture of prepreg tapes by the film impregnation process.

Journal ArticleDOI
TL;DR: In this paper, a hydro-bulging technology for pipe elbows is proposed to overcome difficulties in manufacturing large diameter pipe elbows using traditional technology, and the section profile variation of the toroidal shell during the forming process is discussed.

Journal ArticleDOI
TL;DR: In this paper, the effects of microstructure obtained by varying the laser process parameters on the microhardness profile along the depth were studied in the two kinds of clad layers, and the results showed that a strengthened surface layer was produced on steel 1045 by laser incorporation of Cr3C2 particles, which increased the hardness of the surface layer by 350-400 HV.
Abstract: Laser clad coatings of Ni alloy as well as a composite made from 50 wt% Cr3C2 particles coated with a Ni–Cr alloy and Ni-base alloy on steel 1045 were investigated by scanning electron microscopy (SEM), X-ray diffraction (XRD), energy-dispersive X-ray analysis (EDX) and microhardness tests, respectively. The effects of microstructure obtained by varying the laser process parameters on the microhardness profile along the depth were studied in the two kinds of clad layers. The results showed that a strengthened surface layer was produced on steel 1045 by laser incorporation of Cr3C2 particles, which increased the hardness of the surface layer by 350–400 HV. The presence of undissolved Cr3C2 particles, the formation of dense dendrites surrounded by a fine eutectic and the precipitation of Cr7C3, Fe23(C, B)6 compounds during rapid solidification after the laser treatments were thought to be the main factors for the strengthening of the composite coating.

Journal ArticleDOI
TL;DR: In this article, the existence of a breathing crack can not only cause variations in harmonic components but also produce extra transient components into vibration signals of a rotor system, and an approach of signal processing is suggested to detect transient components of the vibration signals and thereby the crack.
Abstract: The existence of a breathing crack can not only cause variations in harmonic components but also produce extra transient components into vibration signals of a rotor system. In the present paper, the composition of cracked rotor vibration signals is studied first by some analytical methods. Based on this study, an approach of signal processing is suggested to detect transient components of the vibration signals and thereby the crack.