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排序方式: 共有4983条查询结果,搜索用时 15 毫秒
981.
A. Lakhtakia W. S. Weiglhofer 《International Journal of Infrared and Millimeter Waves》1998,19(8):1073-1082
General linear constitutive relations need not contain any dependence on field derivatives, and the standard boundary conditions need not be modified. We show that the answer to the question asked as the title of this communication is therefore in the negative. 相似文献
982.
Optimal Control of a Chemical Vapor Deposition Reactor 总被引:1,自引:0,他引:1
We study a simple model of chemical vapor deposition on a silicon wafer. The control is the flux of chemical species, and the objective is to grow the semiconductor film so that its surface attains a prescribed profile as nearly as possible. The surface is spatially fast oscillating due to the small feature scale, and therefore the problem is formulated in terms of its homogenized approximation. We prove that the optimal control is bang-bang, and we use this information to develop a numerical scheme for computing the optimal control. 相似文献
983.
First-Order Necessary Optimality Conditions for General Bilevel Programming Problems 总被引:3,自引:0,他引:3
S. Dempe 《Journal of Optimization Theory and Applications》1997,95(3):735-739
In Ref. 1, bilevel programming problems have been investigated using an equivalent formulation by use of the optimal value function of the lower level problem. In this comment, it is shown that Ref. 1 contains two incorrect results: in Proposition 2.1, upper semicontinuity instead of lower semicontinuity has to be used for guaranteeing existence of optimal solutions; in Theorem 5.1, the assumption that the abnormal part of the directional derivative of the optimal value function reduces to zero has to be replaced by the demand that a nonzero abnormal Lagrange multiplier does not exist. 相似文献
984.
A class of multi-objective fractional programming problems (MFP) are considered where the involved functions are locally Lipschitz.
In order to deduce our main results, we give the definition of the generalized (F,θ,ρ,d)-convex class about the Clarke’s generalized gradient. Under the above generalized convexity assumption, necessary and sufficient
conditions for optimality are given. Finally, a dual problem corresponding to (MFP) is formulated, appropriate dual theorems
are proved.
相似文献
985.
986.
K. S. Matviichuk 《International Applied Mechanics》2003,39(3):356-367
Sufficient conditions of technical stability in measure are established for nonstationary automatic-control systems with variable structure and logic control laws dependent on the mismatch error and its derivatives of finite order for all admissible initial perturbations from a predefined measurable set of initial perturbations. The associated systems of differential equations contain time-dependent coefficients. The logic control laws are described by a variable jump control function of the mismatch coordinate and its derivatives of finite order that is no higher than that of the initial system of equations. Using a signal and its derivatives for control increases the quality of discontinuous control. The relationship between the eigenvalues of the quadratic forms of the corresponding Liapunov functions and the criteria of technical stability is revealed. The general results are applied to a variable-structure system of the third order 相似文献
987.
An efficient method for ring-closing metathesis under solvent-free conditions and by microwave activation was established. Non-thermal microwave specific effects were evident. 相似文献
988.
Rochelle R. FerrettMichael J. Hyde Kimberly A. LahtiTimothy L. Friebe 《Tetrahedron letters》2003,44(12):2573-2576
Under microwave irradiation and without solvent, racemic and optically pure mandelic acid readily condenses with aldehydes and ketones to give 2-alkyl substituted 5-phenyl-1,3-dioxolan-4-ones in good yield. 相似文献
989.
A fourth‐order accurate solution method for the three‐dimensional Helmholtz equations is described that is based on a compact finite‐difference stencil for the Laplace operator. Similar discretization methods for the Poisson equation have been presented by various researchers for Dirichlet boundary conditions. Here, the complicated issue of imposing Neumann boundary conditions is described in detail. The method is then applied to model Helmholtz problems to verify the accuracy of the discretization method. The implementation of the solution method is also described. The Helmholtz solver is used as the basis for a fourth‐order accurate solver for the incompressible Navier–Stokes equations. Numerical results obtained with this Navier–Stokes solver for the temporal evolution of a three‐dimensional instability in a counter‐rotating vortex pair are discussed. The time‐accurate Navier–Stokes simulations show the resolving properties of the developed discretization method and the correct prediction of the initial growth rate of the three‐dimensional instability in the vortex pair. Copyright © 2004 John Wiley & Sons, Ltd. 相似文献
990.
E.P Gatsori 《Journal of Mathematical Analysis and Applications》2004,297(1):194-211
In this paper we prove controllability results for some semilinear nondensely defined evolution differential inclusions in Banach spaces with nonlocal conditions. 相似文献