Showing papers by "Nanchang University published in 1999"

A Generalized Decision Logic in Interval-Set-Valued Information Tables

Abstract: A generalized decision logic in interval-set-valued information tables is introduced, which is an extension of decision logic studied by Pawlak Each object in an interval-set-valued information table takes an interval set of values Consequently, two types of satisfiabilities of a formula are introduced Truth values of formulas are defined to be interval-valued, instead of single-valued A semantics model of the proposed logic language is studied

Phase unwrapping by lookup table method: application to phase map with singular points

Abstract: Phase unwrapping by a lookup table method has been used to analyze the phase map with singular points that is derived from a multiple-spatial-carrier-frequency fringe pattern. The phase unwrapping can be performed independently on a pixel-by-pixel basis without refer- ence to the phase values of neighboring pixels, and is relatively insensi- tive to errors. Experimental results are presented that demonstrate the validity of the principle. © 1999 Society of Photo-Optical Instrumentation Engineers. (S0091-3286(99)02812-3)

Constant curved minimal 2-spheres in G(2,4)

Abstract: This paper gives a complete classification for minimal 2-spheres with constant Gaussian curvature immersed in the complex Grassmann manifold G(2,4).

Study on the melting process of nitrocellulose by thermal analysis method

Abstract: The melting process of NC is studied by using modulated differential scanning calorimetry (MDSC) technique, the microscope carrier method for measuring the melting point and the simultaneous device of the solid reaction cell in situ/RSFT-IR. The results show that the endothermic process in the MDSC curve is reversible. It is caused by the phase change from solid to liquid of the mixture of initial NC, decomposition partly into condensed phase products. The values of the melting point, melting enthalpy (ΔHm), melting entropy (ΔSm), the enthalpy of decomposition (ΔHdec) and the heat-temperature quotient (ΔSdec) obtained by the MDSC curve of NC at a heating rate of 10 K min−1 are 476.84 K, 205.6 J g−1, 0.4312 J g−1 K−1, −2475.0 J g−1 and −5.242 Jg−1K−1, respectively. The MDSC results of NC with different nitrogen contents show that with increasing the nitrogen content in NC, the absolute values of ΔHm, ΔSm, ΔHdec and ΔSdec increase.

Spectrophotometric Determination of Europium, Terbium and Yttrium in a Perchloric Acid Solution by the Kalman Filter Approach.

Abstract: In the presence of perchloric acid, rare-earth elements of europium, terbium and yttrium at large concentrations have well-shaped absorption spectra in the ultraviolet region even without the addition of a chromogenic reagent. However, it is difficult to determine each of them individually, because they have serious overlapping peaks. In this study, a chemometric method, Kalman filter, was used to resolve the overlapped spectra and to determine the individual components. In contrast to conventional implementation of the Kalman filter, an absorption-coefficient matrix derived from a set of mixtures of known composition by multiple linear regression (MLR) was found to yield better results in this work. For a set of synthetic mixtures of europium, terbium and yttrium, their molar absorptivities were determined to be 1945, 3756 and 1446, respectively. The proposed method was also applied to the determination of europium, terbium and yttrium in a sample of phosphor powder product; a satisfactory result was obtained.

Computation of generalized real radicals of polynomial ideals

Abstract: For an ordered field (K,T) and an idealI of the polynomial ring\(K\left[ {x_1 , \cdots ,x_n } \right]\), the construction of the generalized real radical\(^{\left( {T,U,W} \right)} \sqrt I \) ofI is investigated. When (K,T) satisfies some computational requirements, a method of computing\(^{\left( {T,U,W} \right)} \sqrt I \) is presented.

Updated Lagrangian polar decomposition method in non‐linear elasticity and its shell element implementation

Abstract: In this paper, the relation between the incremental right stretch tensor by the total Lagrangian (T.L.) description and that by the updated Lagrangian (U.L.) description is obtained. The incremental polar decomposition method without drilling degrees of freedom is developed. The non-linear shell elements using the Biot strain tensor as the strain measure are established. The non-linear finite element formulation based on the polar composition theorem is developed with respect to the U.L. description. As a by-product the material time derivative of the right stretch tensor is given by a new form suitable for numerical evaluations. Two examples demonstrate the feasibility of the proposed incremental polar decomposition method.

On the strict efficiency in a locally convex space

Abstract: In this paper, a new concept, strictly efficient points in locally convex spaces,is introduced, and scalar characterization of a strictly efficient point is established. Furthermore, we study the best approximation property for a strictly efficient point by an equivalent norm.

Influence of variables on the system of real-time measurement of temperature field with iccd as sensor

Abstract: The influence of all variables, such as materials of a measured object, condition of its surface, distance, and shut off time in the measurement of temperature field by colorimetric method with ICCD as sensor, is analyzed theoretically and studied by experiments. The obtained results prove the feasibility and reliability of the developed method.

An observation of crack initiation and early crack growth under impact fatigue loading

Abstract: The micro-characteristics of crack initiation and early crack growth of low carbon steels under low cyclic impact fatigue loading were studied. A split Hopkinson’s bar was used in the impact fatigue test, and SEM was used to examine the evolution of the surface on the post-test specimen. It is revealed that the most favourable position of crack initiation is grain boundaries. On the other hand grain boundaries are an effective obstruction for crack propagation. It is easy for cracks to initiate and grow in grains with straight slip bands, but difficult in grains with cross slip bands. The damage caused by micro-pits growing and linking up are quite shallow.

The real-time measurement of welding temperature field and closed-loop control of isotherm width

Abstract: The real-time measurement of welding temperature field by colorimetric method is described, and with the data acquired from it closed-loop control system of the parameters of temperature field is developed and tested. Experimental results prove that it has high measurement speed (time of a field within 0.5 s) and good dynamic response quality. Weld penetration can be controlled satifactorily under unstable welding condition.

Torsional buckling of spherical shells under circumferential shear loads

Abstract: By the aid of differential geometry analysis on the initial buckling of shell element, a set of new and exact buckling bifurcation equations of the spherical shells is derived. Making use of Galerkin variational method, the general stability of the hinged spherical shells with the circumferential shear loads is studied. Constructing the buckling mode close to the bifurcation point deformations, the critical eigenvalues, critical load intensities and critical stresses of torsional buckling ranging from the shallow shells to the hemispherical shell are obtained for the first time.

A mathematical theory of materials with elastic range and the definition of back stress tensor

Abstract: In this paper, the theory of materials with elastic range by Lucchesi and Podio-Guidugli (1988) has been generalized. It has also shown that there are some difficulties on the definition of back stress as the “center” of the yield surface in the Cauchy space. The back stress tensor is Lagrangian, and must be defined in the Lagrangian stress space.

The Resolution for Ruogh Propositional Logic with Lower (L) and Upper (h) Approximate Operators

Abstract: Based on First-Order Rough Logic Studied by Lin and Liu, this paper establishes rough propositional logical system with rough lower (L) and upper (H) approximate operators. It discusses the resolution principle in the system. The soundness of resolution deduction, soundness and completeness of the refutation are also studied in the paper.

First Order Rough Logic-Revisited

Abstract: Based on axiomatic rough set theory, first order rough logic was developed earlier. In this paper, a new model theory for that logic is introduced. With this new semantic, first order rough logic is shown to be equivalent to first order S5, and hence consistent and complete.

Nonstandard decision methods for the solvability of real polynomial equations

Abstract: For a multivariate polynomial equation with coefficients in a computable ordered field, two criteria of this equation having real solutions are given. Based on the criteria, decision methods for the existence of real zeros and the semidefiniteness of binary polynomials are provided. With the aid of computers, these methods are used to solve several examples. The technique is to extend the original field involved in the question to a computable non-Archimedean ordered field containing infinitesimal elements.

Micromechanics Constitutive Modeling for Polycrystalline Sma

Abstract: A micromechanics constitutive model for martensite transformation of polycrystalline shape memory alloys is proposed. The model is established on the following bases: (1) the transformation theory of unconstrained single crystal shape memory alloys, (2) the proper simulation for the evolution of microstructure, i.e., nucleation and growth of marten-site variants, (3) the effect of orientation distribution on transformation process. Theoretical predictions of this model are in agreement with the available experimental observations.

[Determination of As, Hg and Mo in niuhuang jiedu tablets and other Chinese traditional medicines with graphite furnace AAS].

Abstract: The determination of As, Hg and Mo in the composite Chinese traditional medicines such as niuhuang jiedu tablets etc. Indicates the existence of As, Hg and Mo in these medicines. The relation between these elements and the efficacy of the medicines was studied, showing that these elements play an important role in the efficacy of the drugs.

Fractal structures and their computer simulation in rapidly quenched Ai-Mn alloys

Abstract: The microstructure of rapidly quenched A1-Mn alloys were studied by TEM and SEM. The icosahedral phase in AI-Mn alloys was observed to show various types of fractal morphologies, which may be classified into four kinds: 1) dendritic shape, 2) flower-like shape, 3) granular shape and 4) grain-oscillation shape. After being digitized by a computer, the fractal dimensions (D) of these morphologies were calculated. Based on the traditional diffusion limited aggregation (DLA) model computer simulations were made with two-seeded and many-seeded clusters, which reflect the growing mechanism of some fractal structures in A1-Mn alloys. It is suggested that these fractal structures are formed by many icosahedral particles about 20 nm in size aggregating during the rapid quenching process.