Showing papers by "Tsinghua University published in 1982"
TL;DR: In this paper, a new approach for detection and identification of ultiple bad data is presented, which has been developed in order to improve the performance of static-state estimators of power systems.
Abstract: This paper presents a new approach for detection and identification of ultiple bad data --- estimation-identification approach which has been developed in order to improve the performance of static-state estimators of power systems. It describes the important function of detection and identification of bad data which is of crucial importance in designing a static-state estimator as a basic element in power system real-time control; it also discusses tthe basic principle, method of solution and programing technique of so called "Estimation-Identificaition Approach" which is based on the better utilization of the resources of residues and the analysis of the property of its sensitivity matrix; and some test results of simulation on a model system and a practical searching system of doubtful data are given. Test results of identifying bad data is good, it is usually successful especially in the case of the occurence of multi-bad data. At the end of this paper comments concerning the advantages of this approach and its recommendation as a prospective practical approach in real-time applications are given.
104 citations
TL;DR: In this article, three photographs of the wave propagation process and measured velocity-time dependence curves were presented, and it was found that the dark lines observed in white-light photographs correspond to a perpendicular alignment state of the director.
Abstract: In a homeotropic nematic cell, a solitarylike director wave is excited by a mechanical method. Three photographs of the wave propagation process and measured velocity-time dependence curves are presented. By means of the interference patterns of focused polarized light, it was found that the dark lines observed in white-light photographs correspond to a perpendicular alignment state of the director.
79 citations
TL;DR: In this paper, the possibility of calculating the thermodynamic equilibrium data in the metal extraction system UO2Cl2-TBP by using the existing theories of solution is discussed, and a systematic thermodynamic approach for calculating component activity coefficients in the ternary organic phase is described.
15 citations
TL;DR: In this paper, a general treatment and residual values of Chien's solution for large deflection of circular plates are given, and the asymptotic behavior of the solution is studied.
Abstract: A general treatment and residual values of Chien's solution for large deflection of circular plates are given. By means of the above results, the asymptotic behavior of Chien's solution is studied. Two examples of uniform load and concentrated load are discussed, respectively.
8 citations
TL;DR: In this article, corrections to the baryon mass spectrum when the u and the d quarks are massive were considered, i.e. the pion acquires its physical mass.
8 citations
TL;DR: Based on the known composition of the aqueous phase, a thermodynamic extraction equilibrium model can be used to solve for the equilibrated organic component concentrations simultaneously as discussed by the authors, and the predicted compositions are in good agreement with the experimentally measured results.
6 citations
TL;DR: The isotropic liquid (I), nematic (N), and smectic A(A) phase diagrams of homologous series of liquid crystals obtained experimentally may be divided into at least four types (Fig. 1 a-d) according to the characteristic behavior of TNI as discussed by the authors.
Abstract: The isotropic liquid (I) ⊥ nematic (N) ⊥ smectic A(A) phase diagrams of homologous series of liquid crystals obtained experimentally may be divided into at least 4 types (Fig. 1 a-d) according to the characteristic behavior of TNI.
3 citations
TL;DR: In this article, the angular distribution of ground-state alpha particles, measured at nine resonances, suggested spin and parity for eight levels and level-interference effect for one level.
Abstract: Excitation energies and strengths of sixty-eight resonances in the compound nucleus /sup 31/P formed by the reaction /sup 30/Si(p,..cap alpha..)/sup 27/Al were observed in the energy range E/sub p/ = 4.90--6.08 MeV. The natural widths of eighteen resonances are reported. The observed level density has been found in good agreement with a semiempirical theory. Angular distributions of ground-state alpha particles, measured at nine resonances, suggested spin and parity for eight levels and level-interference effect for one level.
3 citations
TL;DR: In this paper, a new quadratic form function for elastic-plastic impact problems is introduced, which possesses diagonalized consistent mass matrix, and non-vanishing effect of internal stress to the equations of motion.
Abstract: There are some common difficulties encountered in elastic-plastic impact codes such as EPIC[1,2], NONSAP[3] etc. Most of these codes use the simple linear functions usually taken from static problems to represent the displacement components. In such finite element formulation, the strain and stress components are constants in every element. In the equations of motion, the stress components in general appear in the form of their space derivatives. Thus, if we use such form functions to represent the displacement components, the effect of internal stresses to the equations of motion vanishes identically. The usual practice to overcome such difficulties is to establish as self-equilibrium system of internal forces acting on various nodal points by means of transforming equations of motion into variational form of energy relation through the application of virtual displacement principle. The nodal acceleration is then calculated from the total force acting on this node from all the neighbouring elements. The transformation of virtual displacement principle into the variational energy form is performed on the bases of continuity conditions of stress and displacement throughout the integrated space. That is to say, on the interface boundary of finite element, the assumed displacement and stress functions should be conformed. However, it is easily seen that, for linear form function of finite element calculation, the displacement continues everywhere, but not the stress components. Thus, the convergence of such kind of finite element computation is open to question. This kind of treatment has never been justified even in approximation sense. Furthermore, the calculation of nodal points needs a rule to calculate the mass matrix. There are two ways to establish mass matrix, namely lumped mass method and consistent mass method [4]. The consistent mass matrix can be obtained naturally through finite element formulation, which is consistent to the assumed form functions. However, the resulting consistent mass matrix is not in diagonalized form, which is inconvenient for numerical computation. For most codes, the lumped mass matrix is used, and in this case, the element mass is distributed in certain assumed proportions to all the nodal points of this element. The lumped mass matrix is diagonalized with diagonal terms composed of the nodal mass. However, the lumped mass assumption has never been justified. All these difficulties are originated from the simple linear form functions usually used in static problems. In this paper, we introduce a new quadratic form function for elastic-plastic impact problems. This quadratic form function possesses diagonalized consistent mass matrix, and non-vanishing effect of internal stress to the equations of motion. Thus with this kind of dynamic finite element, all above-said difficulties can be eliminated.
3 citations
TL;DR: In this article, a thin plate theory is used to solve the restricted torsion of narrow rectangular cross section as this problem is equivalent to the bending of a rectangular cantilever plate by a twisting moment at the free end.
Abstract: Kirchhoff's thin plate theory is used to solve the restricted torsion of narrow rectangular cross section as this problem is equivalent to the bending of a rectangular cantilever plate by a twisting moment at the free end. The results obtained not only prove the angle of twist obtained by Prof. Timoshenko using the energy method but give us stresses.
2 citations
01 Jan 1982
TL;DR: In this paper, the wave functions of the interacting boson model II of nuclei are derived and a formula of energy spectrum with dynamical symmetry U(5) is given.
Abstract: In the interacting boson model II of nuclei (often referred to as IBM-II), the protonpairs and neutron pairs are treated as two kinds of bosons, i.e. the proton bosons and theneutron bosons. Such a description is obviously more reasonable. In order to develop such atheory, there are some new problems needed to be solved. Using the basic theory of Lie groupwe shall discuss these problems in some succeeding papers.In this paper, the general characters of thhe IBM-II are discussed, the wave functions ofIBM-II characterized by the Lie algebra chain U(6)?U(5)?SO(3) are derived, and aformula of energy spectrum with dynamical symmetry U(5) is given. Here we use the term"Lie algebra chain" in order to coincide with the term "graded Lie algebra chain" indiscussion of odd nuclei.
TL;DR: In this article, a curve of equal cavitation number (abbreviated as ECN curve) is proposed for bucket-based high-dam spillways based on simplified analysis, equations for the calculation of such acurve are developed.
Abstract: A curve of equal cavitation number (abbreviated as ECN curve) is proposed for bucketsof high-dam spillways. Based on simplified analysis, equations for the calculation of such acurve are developed. These equations may be conveniently solved by a Runge-Kutta schame.Applications to high-dam spillways show that the effective head of a spillway as far as cavita-tion potential is concerned may be substontially reduced by adopting the ECN curve for thebucket. In one case, the effective head of a spillway with a drop of 111.5 m is thus reduced to62 m.
01 Jan 1982
TL;DR: In this article, the wave functions of IBM-TI characterized by the Lie algebra chainU(6)?SU(3)?SO(3) are calculated and a formula of energy spectra with dynamical sym-metry SU(3).
Abstract: In this paper the wave functions of IBM-TI characterized by the Lie algebra chainU(6)?SU(3)?SO(3) are calculated and a formula of energy spectra with dynamical sym-metry SU(3) is derived
TL;DR: In this article, the results of tests using conventional triaxial apparatus with loading and unloading, on samples of medium sand with two different unit weights were used to study the elastic and plastic volumetric and axial strains under the conditions of hydrostatic and deviator stress.
Abstract: This paper describes the results of tests using conventional triaxial apparatus with loading and unloading, on samples of medium sand with two different unit weights. The method is used to study the elastic and plastic volumetric and axial strains under the conditions of hydrostatic and deviator stress. It is shown that under hydrostatic compression, the elastic volumetric strain of medium sand is always greater than its plastic volumetric strain. The ratio of elastic volumetric strain to plastic volumetric strain may decrease as the hydrostatic pressure increases. Other conclusions are also described.
01 Jan 1982-Precision Engineering-journal of The International Societies for Precision Engineering and Nanotechnology
TL;DR: An automatic alignment direct step-on-wafer (dsw) projection system with automatic alignment accuracy better than ±0.25 μm and useful achievable resolution is 1.5 μm or better.
Abstract: This paper describes an automatic alignment direct step-on-wafer (dsw) projection system. Automatic alignment accuracy is better than ±0.25 μm and useful achievable resolution is 1.5 μm or better. Stepping of the stage is achieved using a record ruler (glass scale) and photoelectric microscope. Its precision is better than ±0.33 μ m (3 σ). Also included in the system is a reticle box with automatic reticle detection and selection, high pressure pulsed mercury lamp and uv light integrating exposure controller as well as a closed-circuit tv viewing and display system. The fundamental design, some experimental testing data and error analysis of the machine are described briefly in this paper
01 Jan 1982
TL;DR: In this paper, the Faraday effect, polar and transverse magneto-optical Kerr effects and optical activity of quartz rotators are generalized in the form of dielectric tensors containing off-diagonal and symmetrical complex conjugate elements.
Abstract: In a fiberoptic rotation sensor a nonreciprocal phase shift modulation is usually introduced to determine the difference of phase produced by the rotation of the sensor. It is also necessary that some frequency bias technique with nonreciprocal propagation properties be used to prevent lock-in in ring laser gyroscopes. Faraday effect, polar and transverse magneto-optical Kerr effects and optical activity of quartz rotators, which are used in the four frequency differential laser gyro and magnetic mirror laser gyro, can be generalized in the form of dielectric tensors containing off-diagonal and symmetrical complex conjugate elements.
TL;DR: In this paper, the diagonalized consistent mass matrix is found for the triangular ring element in axisymmetrical problems, which eliminate the feeling of uncertainty and arbitrariness of lumped mass method on the one hand and the difficulty of computation due to non-diagonalized character of consistent mass method.
Abstract: In this paper, the diagonalized consistent mass matrix is found for the triangular ring element in axisymmetrical problems. The results of this work eliminate the feeling of uncertainty and arbitrariness of lumped mass method on the one hand and the difficulty of computation due to non-diagonalized character of consistent mass method on the other. This paper gives also the foundations of the finite element analysis of elastic-plastic axisymmtrical impact problems.
TL;DR: In this paper, a new manufacturing and freezing technology for photoelastic materials which produces stress-optical coefficient ratios,B/A, different from −0.5, was suggested.
Abstract: This paper suggests a new manufacturing and freezing technology for photoelastic materials which produces stress-optical coefficient ratios,B/A, different from −0.5. By means of the absolute relardation method and the immersion method, the complete experimental stress solutions for the sphere under diametrical compression and for the closure head of a high-pressure vessel have been found.
01 Jan 1982
TL;DR: This paper is concerned with describing effective LSI CAD system - QCADS for minicomputer - and design objectives and strategy of the system and CAD description language.
Abstract: The computer aided design (CAD) technique for LSI is an indispensable tool to develop LSI. Setting up a LSI CAD system with center on CAD database would make CAD technique more effectual. And a LSI CAD system for minicomputer has advantages of lower cost and convenient management. In this paper we are concerned with describing effective LSI CAD system - QCADS for minicomputer. The paper consists of four parts: (1) design objectives and strategy of the system, (2) framework of the system structure, (3) logical structure of database and (4) CAD description language.
TL;DR: The interconnection topology and the mode of control for such an experimental system are described, and its characteristic performance values, such as data-line utilization, mean total message transmission time, etc, are given as results of simulation.
01 Jan 1982
TL;DR: In this paper, a survey of present status of solar energy utilization in China is presented, and the economic value and effects of the utilization are discussed, the requirement for further development of solar power utilization has been evaluated and the prospects of the near future are given.
Abstract: A survey of present status of solar energy utilization in China is presented, and the economic value and effects of the utilization are discussed. The requirement for further development of solar energy utilization has been evaluated and the prospects of the near future are given.
01 May 1982
TL;DR: Speech signal can be quantized by an optimum quantization charateristic (OGC) designed to match a specific power-limited PDF in order to meet certain SNR and entropy requirements.
Abstract: The problems of adaptive quantization and prediction in a DPCM system are analyzed. It is shown that while quantizing speech signal with an adaptive algorithm, the probability distribution of P i associated with the quantization intervals is not uniquely determined by the PDF of speech, but can be controlled by the adaptive parameters (G i ) and algorithm of adaptation. Thus, speech signal can be quantized by an optimum quantization charateristic (OGC) designed to match a specific power-limited PDF in order to meet certain SNR and entropy requirements. This paper derives a PDF with the maximum SNR which is greater than that of Gaussian PDF in 0.5dB. Moreover, the calculation of SNR in an adaptive quantizer and the method for searching adaptive parameters (G i ) are discussed. Finally, a constant-increment sequential adaptive prediction algorithm is developed. It removes multiplier with a prediction gain loss less than 0.5dB.