Showing papers by "Dalian University of Technology published in 1991"
TL;DR: It is suggested that recursive logic is the logic of design, and many well-known design methodologies such as the pattern language given by Alexander can find their explanations in this logic scheme.
173 citations
TL;DR: In this article, a new method for producing dropwise condensation of steam is presented by preparing surface alloys which possess low surface energy in the metallic surface, and four kinds of surface alloy of copper are made by applying ion-implantation technology.
52 citations
41 citations
TL;DR: In this paper, the influences of Mo oxidation states and its configuration on both metathesis reaction and its competing side reactions, in particular carbon deposition, are described and molecular identifications of these species were obtained via XPS and ESR techniques.
40 citations
TL;DR: In this paper, a thin film of condensate exists on the area among the droplets and also a film still exists at the spots from which the dropped droplets departed, and a mechanism of the dropwise condensation (droplets and film coexisting) is presented.
40 citations
TL;DR: In this paper, a three-zone cutting model for a tool with negative primary land is proposed, in which there exists a "dead metal zone" at the edge of the cutting tool.
39 citations
TL;DR: In this article, the absorption spectra of thirty pyridone azo dyes have been examined in binary mixtures of water with acetone, ethanol or dimethylsulf oxide (DMSO).
37 citations
TL;DR: A new and efficient method is presented for the solution of general non-linear programming problems in which a multi-constrained problem is converted to one with a single parametric constraint, derived by using the two concepts of constraint surrogation and maximum entropy.
Abstract: This paper presents a new and efficient method, referred to as an aggregate constraint method, for the solution of general non-linear programming problems in which a multi-constrained problem is converted to one with a single parametric constraint. This is derived by using the two concepts of constraint surrogation and maximum entropy, and represents a uniform approximation to the original constraint set. An augmented Lagrangean algorithm is then used to solve the resulting problem. Numerical examples are given to show the high efficiency of the present method.
32 citations
TL;DR: A refinement totrie hashing, trie hashing with controlled load (THCL), is presented, designed to control the load factor of a TH file as tightly as that of a B-tree file, and allows high load factor for ordered insertions and increases the load factors for random insertions.
Abstract: Trie hashing (TH), a primary key access method for storing and accessing records of dynamic files, is discussed. The key address is computed through a trie. A key search usually requires only one disk access when the trie is in core and two disk accesses for very large files when the trie must be on disk. A refinement to trie hashing, trie hashing with controlled load (THCL), is presented. It is designed to control the load factor of a TH file as tightly as that of a B-tree file, allows high load factor of up to 100% for ordered insertions, and increases the load factor for random insertions from 70% to over 85%. It is shown that these properties make trie hashing preferable to a B-tree. >
26 citations
TL;DR: A necessary and sufficient condition for the space S 1 2 (Δ ( m) 2 ) to contain a nonpolynomial is obtained, where Δ ( m ) 2 is a 2-dimensional Morgan-Scott triangulation.
25 citations
TL;DR: In this article, it was found that the ability of a sliding slider to form an oil film can be determined by surface waviness which can be characterized by a W n and wavelength parameter λ 0.5 x.
TL;DR: In this paper, the side-chain alkylation of toluene with methanol catalyzed by the modified binary zeolite catalysts of KX and Al2O3, KX, KY, KM, or KZSM-5 has been studied.
TL;DR: In this article, the microstructure characteristics of NiTi shape memory alloy manufactured by explosive compaction of elemental and titanium powder and subsequent heat treatment have been investigated in detail by transmission electron microscopy, diffraction and EDX analysis, the crystal structure and the distribution of the phase existed in the sample have been identified.
Abstract: In the present paper the microstructure characteristics of NiTi shape memory alloy manufactured by explosive compaction of elemental and titanium powder and subsequent heat treatment have been investigated in detail. It shows that the NiTi intermetallic compound can be obtained in the whole specimen and a good shape memory effect can be obtained. However there are some differences in microstructure between this explosive compact NiTi shape memory alloy and that of cast/wrought one. By transmission electron microscopy, diffraction and EDX analysis, the crystal structure and the distribution of the phase existed in the sample have been identified. There is a phase of face centered cubic lattice with a lattice constant a = 4.35 A inside the grain of NiTi intermetallic compound and its composition is about Ti 8 Ni. The secondary phase particles in grain boundaries are generally Ti 2 Ni. A comparison between this explosive compacted NiTi alloy and the cast/wrought NiTi alloy has also been made.
TL;DR: In this article, the grain boundary precipitation strengthening and combined matrix/boundary strengthening are modeled following the concept of hard-soft composite structure, and a unified creep equation is derived by taking account of back stress from intergranular carbide particles, "boundary obstacle stress".
Abstract: High temperature creep behavior of carbide precipitation strengthened Fe-15 Cr-25 Ni alloys with different carbon content have been investigated. Grain boundary carbides obstruct dislocation annihilation at the grain boundary and, therefore, increase the dislocation density near the grain boundary. This gives rise to formation of a hard grain boundary region and significantly increase creep resistance of the alloy. The grain boundary precipitation strengthening and combined matrix/boundary strengthening are modeled following the concept of hard-soft composite structure, and a unified creep equation is derived by taking account of back stress from intergranular carbide particles, “boundary obstacle stress”. The models and analysis show that grain boundary precipitation strengthening is predominant for soft matrix but decreases with the increase of matrix strength, indicating the existence of coupled matrix/boundary strengthening.
TL;DR: In this paper, NiSO 4 /γ-Al 2 O 3 catalysts were prepared by impregnation and calcined in dry air at 450-600°C and showed very high oligomerization activities for propene.
01 Jul 1991
TL;DR: In this article, the localization phenomenon for high-frequency vibration modes of imperfectly repetitive structures is considered by using an analogy between computational structural mechanics theory and optimal cepstral geometry.
Abstract: The localization phenomenon for high-frequency vibration modes of imperfectly repetitive structures is considered by using an analogy between computational structural mechanics theory and optimal c...
01 Jan 1991
TL;DR: Numerical results show that for annular plate and Euler beam elements the approximate sensitivity calculated with the semi-analytic method can be improved by adding second order terms, which is a desirable feature.
Abstract: Sensitivity analysis is one of the cornerstones for the development of computer aided structural shape optimization softwares. The semi-analytic sensitivity analysis method proposed in recent years has provided an easy way to integrate the existing general purpose FEM and optimization packages [1,2]. Nevertheless, the method is suffered from the inaccuracy problem if the size of the perturbed bending elements becomes too small. An alternative forward/backward finite difference scheme has been studied to reduce the possible error and implemented in MCADS [3,4]. This paper further investigates the problem and suggests ways to improve the accuracy of the semi-analytic sensitivity analysis. It is shown in this paper that for annular plate and Euler beam elements the approximate sensitivity calculated with the semi-analytic method can be improved by adding second order terms. For a typical beam example the improvement is estimated by making use of computer algebra software “MUMATH” to manipulate the approximate sensitivity and its second order correction. Numerical results also show that for Timoshenko beam elements the accuracy of semi-analytic method is much less dependent upon the element size, which is a desirable feature.
TL;DR: In this article, the Jacobi sums over a ring of residues modulo a prime power were studied and the basic relationship between Gauss sums and Jacobi sum was obtained, which allows us to determine the absolute value of the JacobI sums.
TL;DR: Li et al. as discussed by the authors modified the original Patel-Teja equation of state by replacing the repulsive term of the original equation with the Camahan-Starling expression, which allowed for significant improvements in liquid volumetric predictions of 54 pure non-polar and polar compounds.
TL;DR: In this paper, the general equations of dynamic stability for composite laminated plates are derived by Hamilton principle and the solutions of the fundamental equations show that some important characteristics of the dynamic instability can only be got by the consideration and analysis of those factors.
Abstract: In this paper, the general equations of dynamic stability for composite laminated plates are derived by Hamilton principle. These general equations can be used to consider those different factors that affect the dynamic stability of laminated plates. The factors are transverse shear deformation, initial imperfections, longitudinal and rotational inertia, and ply-angle of the fiber, etc. The solutions of the fundamental equations show that some important characteristics of the dynamic instability can only be got by the consideration and analysis of those factors.
TL;DR: In this article, the degeneration of the eigenvalue equation of the discrete-time linear quadratic control problem to the continuous-time one when Δt→0 is given first.
Abstract: The degeneration of the eigenvalue equation of the discrete-time linear quadratic control problem to the continuous-time one when Δt→0 is given first. When the continuous-time n-dimensional eigenvalue equation, which has all the eigenvalues located in the left half plane, has beeh reduced from the original 2n-dimensional one, the present paper proposes that several of the eigenvalues nearest to the imaginary axis be obtained by the matrix transformation Ae=eA. All the eigenvalues of Ae are in the unit circle, with the eigenvectors unchanged and the original eigenvalues can be obtained by a logarithm operation. And several of the eigenvalues of Ae nearest to the unit circle can be calculated by the dual subspace iteration method.
TL;DR: Based on the orthogonal approach for hybrid element methods, refined three-dimensional isoparametric hybrid hexahedral elements have been developed as mentioned in this paper, and the behaviour of the proposed models are discussed in respect of coordinate invariance, spurious zero energy modes and the ability to pass the patch test.
Abstract: Based on the orthogonal approach for hybrid element methods, refined three‐dimensional isoparametric hybrid hexahedral elements have been developed The behaviour of the proposed models are discussed in respect of coordinate invariance, spurious zero energy modes and the ability to pass the patch test By adopting the orthogonality of strain energy, the element stiffness matrix can be decomposed into a series of stiffness matrices in which the implementational effectiveness can be improved A number of examples is used to demonstrate the implementation efficiency, accuracy and distortion insensitivity of the proposed elements, and its capacity of handling nearly incompressible materials
TL;DR: Using the linear-response dielectric theory, the electronic stopping power for slow atoms in solids is investigated and various theoretical results are compared with each other and with available experimental data.
Abstract: Using the linear-response dielectric theory, we have investigated the electronic stopping power for slow atoms in solids. The effect of the electrons bound to the projectile is considered according to the Brandt-Kitagawa (BK) model (Phys. Rev. B 25, 5631 (1982)). Using a local-field-correction dielectric function, the correlation and exchange interaction of the electron gas in solids is also taken into account. An analytical formula for the stopping power is obtained, and various theoretical results are compared with each other and with available experimental data.
TL;DR: In this article, the effect of fluid flow induced by electromagnetic stirring on dendritic structure of Al-4% Si alloy has been investigated experimentally, and it was found that the fluid flow modified the dendrite structure, and along with the increasing velocity of the flow, the Dendrite spacing changed from large passing small to large.
Abstract: The effect of fluid flow induced by electromagnetic stirring on dendritic structure of Al-4% Si alloy has been investigated experimentally. It was found that the fluid flow modified the dendritic structure, and along with the increasing velocity of the flow, the dendrite spacing changed from large passing small to large.
01 Jan 1991
TL;DR: In this article, multi-directional irregular waves are simulated on the basis of the given directional spectrum using a double summation model, a single directional per frequency model and a single summation approach.
Abstract: Multi-directional irregular waves are simulated on the basis of the given directional spectrum using a double summation model, a single directional per frequency model and a single summation model. Their results are compared and show that the single direction per frequency model proposed in this paper can generate a realistic wave field. The effects of the model parameters on the simulated results are also studied in this paper and the corresponding suggestions are given.
TL;DR: In this article, by the property of conjugate operator, the authors give a method to construct the general solutions of a system of partial differential equations, which is not only theoretical significance, but also practical value.
Abstract: Solving partial differential equations was not only theoretical significance, but also practical value. In this paper, by the property of conjugate operator, we give a method to construct the general solutions of a system of partial differential equations.
TL;DR: In this article, two alternative methods of formulating the recently proposed quadrilateral plane element Qcs6, which is based on a generalized functional with multiple stress fields, are discussed. And both methods can be applied to other structural element formulations with enhanced efficiency.
Abstract: This article discusses two alternative methods of formulating the recently proposed quadrilateral plane element Qcs6, which is based on a generalized functional with multiple stress fields. The first method is derived by an extended Hu-Washizu Principle with the presence of incompatible modes and enforcement of energy orthogonality, while the second one is established on a non-conventional discrete local stress smoothing. Both methods can be applied to other structural element formulations with enhanced efficiency.
01 Feb 1991
TL;DR: In this paper, the microstructure induced by deformation is different from that induced by thermomechanical cycles, and the effects on the thermoelastic martensite transformation are also not the same at all.
Abstract: Microstructures of martensite in a Cu-26.4Zn-4.8Al shape memory alloy after deformation and thermomechanical cycles are reported. By detailed transmission electron microscopy investigation, it is clearly established that the microstructure induced by deformation is different from that induced by thermomechanical cycles, and the effects on the thermoelastic martensite transformation are also not the same at all. The microstructure of martensite induced by deformation is mainly deformation twins when the deformation exceeds the range of recoverable strain of the shape memory alloy. The main microstructure characteristic of martensite which has undergone thermomechanical cycles is regularly distributed dislocations, which are mainly aligned but sometimes tangled. Micro-twins similar to those found in deformed martensite and crossed bands also exist inside the martensite of samples after thermomechanical cycles, but the amounts are too small to be regarded as important microstructure features.
01 Jan 1991
TL;DR: In this article, the mathematical formulation of rigid finite element method (RFEM) is given for elastic analysis and elastoplastic analysis as well as to limit and shakedown analysis.
Abstract: The mathematical formulation of Rigid Finite Element Method (RFEM) is given in this paper. Its applications to elastic analysis and elastoplastic analysis as well as to limit and shakedown analysis will be presented here for illustrating its advantages: namely saving of the computational work and improving of the accuracy of stress as compared with traditional FEM. It is expected that RFEM will be useful in diverse fields of structural analysis, especially in the Soil and Rock Mechanics in which the constitutive law belong to the Coulomb type.