Showing papers by "Harbin Institute of Technology published in 1986"

The multi-purpose incremental learning system AQ15 and its testing application to three medical domains

Abstract: AQ15 is a multi-purpose inductive learning system that uses logic-based, user-oriented knowledge representation, is able to incrementally learn disjunctive concepts from noisy or overlapping examples, and can perform constructive induction (i.e., can generate new attributes in the process of learning). In an experimental application to three medical domains, the program learned decision rules that performed at the level of accuracy of human experts. A surprising and potentially significant result is the demonstration that by applying the proposed method of cover truncation and analogical matching, called TRUNC, one may drastically decrease the complexity of the knowledge base without affecting its performance accuracy.

The multivariate N-Component resolution problem with minimum assumptions

Abstract: The present state of the minimum assumption multivariate component resolution theory is outlined. Some new developments are presented: limiting function domains; the analytical expression for the limiting function; efficient algorithms for defining the FIRPOL and INNPOL hyperpolyhedrons. A very low resolution data set is analyzed.

The Fringing Effect in PM Electric Machines

Abstract: To predict the fringing flux distribution along the axial length of a permanent magnet electric machine, a segmented permanent magnet model, in which magnets face a slotted and infinitely permeable boundary, is presented in this paper. By using the model and the method of Fourier expansion, the analytical solution to the fringing field problem can be easily determined. With the aid of the analytical results, the effective armature length for permanent magnet electric machines due to the axial extension of the magnet may be obtained.

A New Type of Three-Component Dynamometer with High Stiffness and High Natural Frequency

Abstract: In order to research machine-tool dynamics and dynamic cutting force more thoroughly, three-component dynamometer with higher natural frequency and higher static stiffness is needed. A new type of the dynamometer has been designed and made by the authors. Its static stiffnesses are more than 1500 kgf/um and natural frequecies are more than 15000 Hz. It is a strain dynamometer and its sensitivities are more than o.6 μɛ/kgf. The weakpoint of tranditional strain dynamometer is analysed in this paper and the structure of the new dynamometer is also given. Shear strain combined with tensile strain is utilized for overcoming the weakpoint in the dynamometer.

The study on defects in single crystal silicon wafers treated with double-Gettering technique

Abstract: Investigations on the nature and states of the defects in single crystal wafers treated with double-gettering technique have been carried out by means of optical microscopy, electron microscopy, electron microanalysis and spread resistance. Phosphorus profile in these wafers was measured. And the effect of phosphorus on defects and resistivity was determined.

Precise calculation of effective emissivity of a diffuse cylindro-inner-cone with a specular lid.

Abstract: A mathematical model for calculating precisely the effective emissivity distribution ∊a of a diffuse cylindro-inner-cone with a plane specular lid is presented. The exchange factors that comprise the kernels of the integral equations for evaluating ∊a have been derived using the image method and contour integration. For the usual case of a highly reflective specular lid, values of ∊a throughout the cavity are slightly lower than when all surfaces are diffuse. On the other hand, if the intrinsic emissivity of the specular lid is numerically the same as the diffuse emissivity of the rest of the cavity walls (an uncommon practical case), ∊a is marginally higher in the specular lid cavity.

Hopf bifurcation in numerical approximation for delay differential equations

Abstract: In this paper we investigate the qualitative behaviour of numerical approximation to a class delay differential equation. We consider the numerical solution of the delay differential equations undergoing a Hopf bifurcation. We prove the numerical approximation of delay differential equation had a Hopf bifurcation point if the true solution does.

Natural Language Interface to Relational Data Base Systems

Abstract: Using natural language interface in a database system allows the user direct access to the information stored in the database system without the need to know the details of the database or to learn a specific formal query language. In this paper, the structure of a NL interface and the architecture of the system are described respectively.

An Intelligent Vision System for Robot

Abstract: An intelligent vision system, LONGJIANG, is studied. In this paper we focus on the cooperation between hardware and software to meet some specified requirements, such as real-time, cost-performance, etc. A view of this system is described as follows: a parallel pipeline suited to neighbourhood processing in real-time is used as the system architecture; and the 3*3 convolution method suited to neighbourhood operation is selected as the system algorithm.

Reasonable Selection of the Stress Modes in a Hybrid Stress Element

Abstract: A reasonable condition is suggested to match the displacements and stresses in a hybrid stress element. Based on Hellinger-Reissner principle the displacement and stress modes are assumed to include the complete polynomials in the natural coordinates of an element. The work done by the assumed stresses on the nonconforming strains in an element should vanish. Taking this as a matching condition the dependent stress parameters can be eliminated and a rank sufficient hybrid stress element can be formulated. it contains the minimum number of stress parameters and is invariant for coordinates. Without perturbation a new 4-node (5 stress parameters) plane hybrid stress element has been developed. It can be arranged to satisfy the patch test. To demonstrate the properties of the element the solutions to some example problems are included

Instability Condition and Frequency-Locking in Hybrid Optical Bistability

Abstract: In the past few years Ikeda instability in optical bistability has attracted much attention1–4. In this paper we define a physical quantity, degree of stability S, in relation to feedback intensity, which is also a factor for controlling the instability condition. We find that frequency-locking in a hybrid OBD with delayed feedback can be obtained by choosing a proper initial condition.

Ring Pattern of Laser-Induced Thermal Self-Defocusing

Abstract: The laser-induced thermal lens effect was first observed in 1964 [1]. If the laser intensity is strong enough, the far-field of a laser beam traversing an absorbing medium may exhibit a ring pattern [2–4]. Many scientists have attempted to explain this effect [2,5], but it has never been fully understood. Recently we proposed a theoretical interpretation for the ring pattern that is clear physically and in agreement with experiments.

Diffraction of elastic waves in the plane multiply-connected region and dynamic stress concentration

Abstract: This paper deals with the problem of diffraction of elastic waves in the plane multiply-connected regions by the theory of complex functions. The complete function series which approach the solution of the problem and general expressions for boundary conditions are given. Then the problem is reduced to the solution to infinite series of algebraic equations and the solution can be directly obtained by using electronic computer. In particular for the case of weak interaction, an asymptotic method is presented here, by which the problem of p waves diffracted by a circular cavities is discussed in detail. Based on the solution of the diffracted wave field the general formulas for calculating dynamic stress concentration factor for a cavity of arbitrary shape in multiply-connected region are given.

Vorticity Measuring Apparatus Using Reciprocal Ultrasonic Transmission Method

Abstract: The authors devised a method to measure vorticity by using the ultrasonic pulse. With this method, measurement was made of the sum total of sound propagation time in the flow direction easy and opposite to the circulating direction of the vortex. The vorticity was then calculated by subtracting the propagation time of the easy flow from that of opposite flow. Taking practical use into consideration, a trial vorticity measuring apparatus was built and its experimentally examined effectiveness was shown by acceptable results.

Optimisation philosophy of acquisition process for tracking radar

Abstract: A theoretical model for the quantitative analysis of sequential acquisition by a tracking radar is presented. The relation between the acquisition performance and radar and designation system parameters is established. A method to optimise the acquisition process is suggested and some numerical examples are given.

The evolution of quasars selected by slitless technique

Abstract: In former works (Zhouet al., 1983, 1985), a quantitative method have been developed to take the selection effects in the identification of emission lines of quasars into account. It was proved that these selection effects may be the cause of the unevenness in the redshift distribution of quasars. The present work is a continuation and development of former works. We use results given by the surveys with same limit-apparent magnitude and choose the quasars whose absolute magnitudes are within a specific range as the analysing samples. Using the method given in the former papers we may find out the evolutionary parameter γ in an evolutionary law with form of (1+z) y from the best fitting between the calculative and observational redshift distribution. The result of analysis shows that the evolutionary law of quasars selected by slitless technique isp =p 0(1 + z)6.5 ± 1 up toz=2.8. This result coincides with and generalizes the earlier result given by other authors.