Showing papers by "Harbin Institute of Technology published in 1996"
TL;DR: In this article, the relationship between the cutting edge radius and the minimum cutting thickness was analyzed, and the effect of cutting edge sharpness on the machined surface integrity was investigated.
331 citations
TL;DR: A simple, direct, complete and explicit parametric solution of the generalized Sylvester matrix equation AV+BW=EVF is proposed for matrix F in the Jordan form with arbitrary eigenvalues using the Smith canonical form of the matrix.
Abstract: A simple, direct, complete and explicit parametric solution of the generalized Sylvester matrix equation AV+BW=EVF is proposed for matrix F in the Jordan form with arbitrary eigenvalues using the Smith canonical form of the matrix [A-sE B]. The obtained solution is in a clear, neat form and may have important applications in descriptor linear system theory.
128 citations
TL;DR: This paper presents a unified white noise estimation theory that includes both input and measurement white noise estimators, and presents a new steady-state optimal state estimation theory.
98 citations
14 Oct 1996
TL;DR: Theoretical analysis and simulation results show that the improved neural network-based identification method has the advantage of identifying both linear and nonlinear dynamic systems without any prior knowledge of their orders and structures.
Abstract: In this paper, an overview of the structure and learning algorithm of the Elman neural network is first presented. A modified Elman network is then proposed by adding new adjustable weights that connect the context nodes with output nodes. Convergence speed of the two network structures are compared. A parallel dynamic system identification scheme based on the modified Elman network is set up as well. Theoretical analysis and simulation results show that our improved neural network-based identification method has the advantage of identifying both linear and nonlinear dynamic systems without any prior knowledge of their orders and structures.
86 citations
TL;DR: In this article, the existence and uniqueness theorem for the solution of the Cauchy problem is obtained for the fuzzy-valued mappings of a real variable whose values are normal, convex, upper semicontinuous, and compactly supported fuzzy sets in R n, where the function f satisfies the generalized Lipschitz condition.
80 citations
TL;DR: In this article, the wear mechanisms of steel 1080 and the wear behaviour of various microstructures in the steel were systematically studied by wear testing, and by SEM and TEM observations of worn surface and wear particles.
69 citations
TL;DR: In this paper, gas tungsten arc welding is analyzed and modeled as a 2-input, 2-output (weld depression and width) multivariable process and a real-time model frame with only a few parameters to be identified on-line is proposed.
Abstract: In this study, gas tungsten arc welding is analyzed and modeled as a 2-input (welding current and arc length) 2-output (weld depression and width) multivariable process. Experiments under a number of typical welding conditions are performed to excite and identify the process characteristics and variations. It is observed that the model parameters vary in a large range with the experimental conditions. A real-time model frame with only a few parameters to be identified on-line is proposed. Based on the obtained models, the process characteristics in terms of inertia, delay, nonminimum phase, and coupling are given. These characteristics suggest an adaptive predictive decoupling control algorithm. By designing and implementing the suggested control algorithm with the real-time model, excellent results have been achieved for both simulation and practical control. This shows that the dynamic analysis and identification provide sufficient process information for design of the control system.
41 citations
41 citations
TL;DR: In this article, a wave function expansion method and singular integral equation technique were used to solve the problem of debonding by a rigid cylindrical inclusion partially debonded from its surrounding matrix, where debonding regions were modeled as multiple arc-shaped interface cracks with non-contacting faces.
41 citations
TL;DR: In this paper, the microstructure, mechanical properties and toughening mechanisms of hot-pressed SiC whiskers (SiCw) reinforced ZrO2 (2 mol% Y2O3) based composites were investigated by using TEM, SEM and XRD techniques and mechanical tests.
31 citations
TL;DR: Under the conditions of different sterilization duration and unequal intensity of microwave power irradiation onto the bacteria, a useful result of killing bacteria has been observed, i.e., the Bacillus subtilis can be considered as an optimum indicator bacterium for microwave sterilization.
Abstract: According to the superiority sterilization, a specially-designed microwave disinfector using high-power microwave energy was made. A series of sterilizing experiments have been made to determine the effect of microwave energy on several typical indicator bacteria such as Bacillus subtilis var. nigar, Bacillus stearothermophilus, Bacillus pumilus E/sub 601/, Staphylococcus aureas, Bacillus cereus. Under the conditions of different sterilization duration and unequal intensity of microwave power irradiation onto the bacteria, a useful result of killing bacteria has been observed, i.e., the Bacillus subtilis can be considered as an optimum indicator bacterium for microwave sterilization.
01 Jan 1996
TL;DR: In this paper, a new approach for defining a fuzzy derivative is introduced and a comparison with a previous approach illustrates the advantages of the new method, and sufficient conditions for existence and uniqueness of solutions to fuzzy initial value problems are given.
Abstract: A new approach for defining a fuzzy derivative is introduced and a comparison with a previous approach illustrates the advantages of the new method. A first order fuzzy differential equation and a fuzzy Cauchy problem are defined and sufficient conditions for existence and uniqueness of solutions to fuzzy initial value problems are given. Solutions are calculated for simple examples.
TL;DR: In this paper, the problem of a circular cylindrical inclusion with uniform eigenstrain in an elastic half-space is studied by using the Green's function technique, and explicit solutions are obtained for the displacement and stress fields.
Abstract: The problem of a circular cylindrical inclusion with uniform eigenstrain in an elastic half-space is studied by using the Green's function technique. Explicit solutions are obtained for the displacement and stress fields. It is shown that the present elastic fields can be expressed as functions of the complete elliptic integrals of the first, second, and third kind. Finally, numerical results are shown for the displacement and stress fields.
TL;DR: The microstructure of laser-clad 60 vol.% ZrO2 plus 40 vol.%. Ni alloy composite coating on steel 1045 was investigated by scanning electron microscopy, electron probe microanalysis, X-ray diffraction, energy-dispersive Xray analysis and microhardness tests.
Abstract: The microstructure of laser-clad 60 vol.% ZrO2 (partially stabilized with 2 mol% Y2O3) plus 40 vol.% Ni alloy composite coating on steel 1045 was investigated by scanning electron microscopy, electron probe microanalysis, X-ray diffraction, energy-dispersive X-ray analysis and microhardness tests. The composite coating consists of a pure ZrO2 clad layer in the outer region and a bonding zone of Ni alloy adjacent to the substrate. The pure ceramic layer exhibits fine equiaxed ZrO2 grains in the outer zone and columnar ZrO2 dendrites in the inner zone, growing from the ceramic layer-bonding zone interface. This ceramic layer is composed of metastable t′-ZrO2 phase and a very small amount of m-ZrO2 phase and displays a microhardness of 1700 HV0.2. The high heating and cooling rate caused by laser cladding restrains the t → m phase transformation in the ZrO2 ceramic layer. Interdiffusion of alloy elements takes place in the bonding zone, in which the coexistence of ZrO2 particles, Ni-based solid solution and (Fe,Cr)23C6 particles in the interdendritic regions was found.
TL;DR: In this paper, the interfacial reactions in SiCw/AZ91 composites prepared by squeeze casting were investigated, with particular emphasis on the morphology, structure and the formation mechanisms of the reaction products using electron microscopy.
TL;DR: In this paper, the authors investigated the thermal shock resistance of hot-pressed SiCw/Si3N4 composites by thermal shock resilience parameters and water quenching test.
TL;DR: In this paper, the sintered body of ZrO2-Ni FGM is almost fully densified, and its chemical composition and microstructure have the expected gradient distribution.
Abstract: Functional gradient material (FGM) of the ZrO2-Ni system was developed by a powder metallurgical process, and investigated for its microstructure by means of X-ray diffractometry (XRD), electron probe microanalysis (EPMA), transmission electron microscopy (TEM) and optical microscopy. It was shown that the sintered body of ZrO2-Ni FGM is almost fully densified, and its chemical composition and microstructure have the expected gradient distribution. With composition variation, the microstructure changes gradually from zirconia particles dispersed in a nickel matrix to the converse with nickel particles dispersed in a zirconia matrix, with network structures in the intermediate composition range. Therefore, no distinct interfaces appear in the FGM due to the gradient change of components, that is, both zirconia and nickel are present everywhere in the microstructure. In phase composition, the sintered ZrO2-Ni FGM consists of nickel, tetragonal zirconia and a little monoclinic zirconia. No reaction between nickel and zirconia has been detected. The substructure of nickel and monoclinic zirconia are twins, and strain fringes can also be found in zirconia.
TL;DR: In this paper, the transient motion of an interface screw dislocation is first studied by the Fourier and Laplace transforms and Cagniard-de Hoop technique, and then the solution of a dislocation moving uniformly from rest is used as a fundamental solution to solve the anti-plane self-similar propagation of a crack under the moving concentrated loads.
TL;DR: In this paper, the effect of the interfacial reaction on the Young's modulus of ABOw/AC8A-A1 composite has been investigated, and the results showed that when the casting temperature is lower than 800°C, the Youngs modulus increases with the increasing casting temperature.
Abstract: The interface plays a very important role in the properties of composites. One of the effects of the interface on the properties of the composite is that it may affect the load transfer from the matrix to the reinforcement. As it is well known that the Young's modulus of composites is influenced mainly by the load transfer [1, 2], the interfacial reaction has a great effect on the bonding and strength of the interface [3], which can affect the Young's modulus of the composite. Recently, a low cost aluminium matrix composite reinforced by aluminium borate whisker (AIIsB4 O33W » denoted by ABOw) has been studied by many researchers [4 8]. Although the interfacial reaction, mechanical properties and ageing behaviours of the composite have been investigated extensively, there have been few studies on the effect of the interfacial reaction on the Young's modulus of ABOw/A1 composite. This letter aims to report this effect. The ABOw/AC8A-A1 composite used was fabricated by the squeeze casting method. The volume fraction of the whisker was 25%. The composition of the matrix alloy was Si: 12.0wt%, Mg: 1.0wt%, Cu: 0.8 wt%, NJ: 1.0 wt%, AI: 85.2 wt%. To obtain different degrees of the interfacial reaction, the composites were fabricated at various temperatures: 660°C, 720°C, 760°C, 800°C and 840°C. The specimens for tensile testing were solutionized at 500 °C for 5 h then quenched into water maintained at 80 °C, to prevent the effect of precipitation on the properties of the composite. The microstructure and the interfacial reaction were studied by transmission electron microscopy (TEM). The specimens for TEM observation were thinned by the ion milling method. The Young's modulus of the composite was measured by the slope of the tensile stress-strain curves. The dependence of Young's modulus of the composites on the casting temperature is shown in Fig. 1. It can be seen that when the casting temperature is lower than 800°C, the Young's modulus of the composite increases with the casting temperature. When the casting temperature is higher that 800 °C, however, the Young's modulus of the composite decreases with increasing casting temperature. That is to say, there exists an optimal casting temperature for the Yourig's modulus of the ABOw/AC8A composite. The microstructure of the ABOw/AC8A composite was studied using TEM. As shown in Fig. 2, an
TL;DR: In this article, the effects of the interlayer thickness, local nonhomogeneous elastic property and distribution parameter k on stress intensity factor and strain energy release rate were investigated in a single-layer model.
Abstract: The effects of the interlayer thickness, local nonhomogeneous elastic property and the distribution parameter k on stress intensity factor and strain energy release rate are presented
TL;DR: The mechanical properties of Al-10Ti alloy prepared by mechanical alloying and subsequent hot hydrostatic extrusion were evaluated at room and elevated temperatures by transmission electron microscopy as discussed by the authors.
Abstract: The mechanical properties of Al-10Ti alloy prepared by mechanical alloying and subsequent hot hydrostatic extrusion were evaluated at room and elevated temperatures. Transmission electron microscopy was used to characterize the microstructural changes of this alloy on heat treatment at 500 °C for various times. The results show that the mechanically alloyed Al-10Ti has high strength and high thermal stability at elevated temperature. The strength and stability of this alloy are attributed to its fine grain size and to the high volume fraction of small Al3Ti intermetallic compounds dispersed in the aluminium matrix. After 50 h annealing at 500 °C, no serious coarsening of either the Al3Ti dispersoids or the grains was observed.
05 Aug 1996
TL;DR: In this paper, an improved passive input current wave-shaping method for single-phase diode rectifiers is presented, which can further lower the input current harmonic components and improve the input power factor.
Abstract: This paper presents an improved passive input current waveshaping method for single-phase diode rectifiers (improved method). The simulation results show that the improved method can further lower the input current harmonic components and improve the input power factor of a single-phase diode rectifier as compared with the novel passive input current waveshaping method for single-phase diode rectifiers proposed by P.D. Ziogas (novel method). The relevant input current and voltage waveforms, the input current total harmonic distortion and the input power factor value are derived from the computer simulation or theoretical analysis. A design example is provided and the simulation results have been verified on a 5 kW experimental models.
TL;DR: This paper presents a new frequency-domain approach to test the second-order harmonic distortion of an analog-to-digital converter (ADC) that uses triple correlation and its Fourier transform, bispectrum, to suppress quantization noise and improve the testing accuracy of weak second- order harmonics.
Abstract: This paper presents a new frequency-domain approach to test the second-order harmonic distortion of an analog-to-digital converter (ADC). It uses triple correlation and its Fourier transform, bispectrum, to suppress quantization noise and improve the testing accuracy of weak second-order harmonics. Our approach is independent of the triggering delay that is a known weakness of the spectral averaging method. The new method is also less sensitive to the quantization noise than the power spectrum averaging method. Both theoretical analyses and illustrative computer simulations are provided.
TL;DR: In this paper, a 3D static mathematical model of a bottomhole assembly (BHA) including steerable downhole motor assembly under large deflection has been established, and the forces and deflections of the drillstring have been accurately computed by making use of the method of weighted residuals, the weighted objective function, and a method of optimization to calculate the tangency point and to reduce the effect of the indistinct tangency points conditions.
Abstract: A 3D static mathematical model of a bottomhole assembly (BHA) including steerable downhole motor assembly under large deflection has been established. The forces and deflections of the drillstring have been accurately computed by making use of the method of weighted residuals, the weighted objective function, and the method of optimization to calculate the tangency point and to reduce the effect of the indistinct tangency point conditions. The effects of the weight on bit, the borehole geometry, the geometry and tool face rotation of the BHA on the bit building, and right walking force have been studied separately. There is a significant difference between the bit forces of large deflection analysis and small deflection analysis.
TL;DR: In this article, a conjugate pair of strain and stress tensors, the Green strain tensor and the Second Piola-Kirchhoff stress tensor are adopted to give the constitutive equation of Mooney material.
TL;DR: The definition of the fuzzy number measures which extends the concepts of the set-valued measures in Banach spaces is introduced and the properties of the indefinite integral of the random fuzzy numbers are discussed.
TL;DR: In this paper, the authors examined the effect of volume fraction of AlN on HSRS behavior of an AlN particulate reinforced 6061 aluminum alloy composite and the maximum volume fraction by which the HSRS could produce in order to understand the deformation mechanism of HSRS.
TL;DR: In this paper, the microstructure of the bonding zones between laser-clad Ni-alloy-based composite coatings and steel substrates was studied by means of scanning electron microscope (SEM) and transmission electron microscope techniques.
Abstract: Microstructure of the bonding zones (BZs) between laser-clad Ni-alloy-based composite coatings and steel substrates was studied by means of scanning electron microscope (SEM) and transmission electron microscope (TEM) techniques. Observations indicate that for pure Ni-alloy coating the laser parameters selected for good interface fusion have no effect on the microstructure of the BZ except for its thickness. However, the addition of ceramic particles (TiN, SiC, or ZrO2) to the Ni alloy varies the compositional or constitutional undercooling of the melt near the solid/liquid interface and consequently leads to the observed changes of microstructure of the BZs. For TiN/Ni-alloy coating the morphology of y-Ni solid solution in the BZ changes from dendritic to planar form with increas-ing scanning speed. A colony structure of eutectic is found in the BZ of SiC/Ni-alloy coating in which complete dissolution of SiC particles takes place during laser cladding. The immiscible melting of ZrO2 and Ni-alloy powders induces the stratification of ZrO2/Ni-alloy coating which consists of a pure ZrO2 layer in the upper region and a BZ composed mainly of y-Ni dendrites adjacent to the substrate. All the BZs studied in this investigation have good metallurgical characteristics between the coatings and the substrates.
TL;DR: In this article, the cylindrical crack problem in the interfacial zone of two coaxial elastic cylinders under torsional loading is considered, and the problem is formulated in terms of a singular integral equation with a Cauchy type kernel.
TL;DR: In this article, the behavior of stacking faults and the two associated Shockley partial dislocations under an applied stress has been examined, and it is shown that the two partials usually experience unequal forces, resulting in further extending or contracting of the stacking fault, and their motion involves crystallographic transformation.