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991.
The coupled numerical simulation on fluid flow, heat transfer, and mass transfer in the process of laser cladding is undertaken on the basis of the continuum model.In the simulation of mass transfer in the laser molten pool, the concentration distribution in the regions on different sides of the interface between cladding layer and substrate is calculated separately and coupled at the co-boundary.The non-equilibrium solute partition coefficient is obtained from equilibrium solute partition coefficient according to the Sobolev model.By using the developed software which is based on the commercial software PHOENICS 1.4, the distribution of Fe in laser molten pool in an experiment of cladding Stellite 6 on 12CrMoV is calculated.The obtained results well coincide with the experimental ones. 相似文献
992.
The three-dimensional (3D) problem of the ground vibration isolation by an in-filled trench as a passive barrier is studied
theoretically. Integral equations governing Rayleigh wave scattering are derived based on the Green’s solution of Lamb problem.
The integral equations are solved accurately and efficiently with an iteration technique. They are used to evaluate the complicated
Rayleigh wave field generated by irregular scatterers embedded in an elastic half-space solid. The passive isolation effectiveness
of ground vibration by the in-filled trench for screening Rayleigh wave is further studied in detail. Effects of relevant
parameters on the effectiveness of vibration isolation are investigated and presented. The results show that a trench filled
with stiff backfill material gets a better isolation effect than a soft one, and increasing the depth or width of the in-filled
trench also improves its screening effectiveness. The effectiveness and the area of the screened zone are surging with the
increase in the length of the in-filled trench.
Supported by the National Natural Science Foundation of China (Grant Nos. 50678128 and 50538010) and the Research Fund for
PhD Student of Chinese College (Grant No. 20050247030) 相似文献
993.
L-Fuzzy拓扑空间中一种新型的强F仿紧性 总被引:8,自引:1,他引:8
本文引入一种新型的强F仿紧性─—Ⅲ型强F仿紧性,它是基于α-局部有限族概念提出的,这种α-局部有限族概念可用于刻划强F可数紧性。 相似文献
994.
In this paper, the idea of random selection in the theorem on gambling system is extended to Markov chains, by using the notion likelihood ratio and an analytic technique. A strong limit theorem on the relative frequency of ordered couple under random selection is established.AMS Subject Classification (2001)
primary 60F15 Secondary 60J10 相似文献
995.
Suppose that independent U(0, 1) weights are assigned to the ${d\choose 2}n^{2}$ edges of the complete d‐partite graph with n vertices in each of the d maximal independent sets. Then the expected weight of the minimum‐weight perfect d‐dimensional matching is at least $\frac{3}{16}n^{1-(2/d)}$. We describe a randomized algorithm that finds a perfect d‐dimensional matching whose expected weight is at most 5d3n1?(2/d)+d15 for all d≥3 and n≥1. © 2002 John Wiley & Sons, Inc. Random Struct. Alg., 20, 50–58, 2002 相似文献
996.
Yixun Shi 《Numerical Linear Algebra with Applications》2002,9(3):195-203
This paper studies the possibility of combining interior point strategy with a steepest descent method when solving convex programming problems, in such a way that the convergence property of the interior point method remains valid but many iterations do not request the solution of a system of equations. Motivated by this general idea, we propose a hybrid algorithm which combines a primal–dual potential reduction algorithm with the use of the steepest descent direction of the potential function. The complexity of the potential reduction algorithm remains valid but the overall computational cost can be reduced. Our numerical experiments are also reported. Copyright © 2002 John Wiley & Sons, Ltd. 相似文献
997.
998.
High aspect-ratio, single crystal BaWO4 nanowires with diameters as small as 3.5 nm and lengths up to more than 50 microns were synthesized in catanionic reverse micelles formed by an equimolar mixture of two surfactants: undecylic acid and decylamine. 相似文献
999.
In this paper, we describe a practical, useful electrophilic aromatic nitration process in fluorous phase by using perfluorodecalin (C10F18, cis- and trans-mixture) as a fluorous solvent and perfluorinated rare earth metal salt [Yb(OSO2C8F17)3] as a catalyst for the electrophilic aromatic nitration. 相似文献
1000.
High chemical yields and good enantiomeric excesses are obtained by using soluble polymer-supported tartrate ester in the epoxidation of trans-hex-2-en-1-ol using Ti(OPri)4/tert-butyl hydroperoxide. 相似文献