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61.
This paper describes an optimization technique based on an heuristic procedure which is applied to analyse and improve the efficiency of the design of Global Positioning System (GPS) surveying networks. GPS is a valuable survey tool because of its ability to increase the accuracy, speed and flexibility of a survey. A GPS network can be defined as a number of stations, which are co-ordinated by a series of sessions, formed by placing receivers on stations. The goal is to select the best order in which these sessions can be organised to give the best possible schedule. Generally, solving large networks to optimality requires impractical computational time. This paper proposes a Tabu Search technique which provides optimal or near-optimal solutions for large networks with an acceptable amount of computational effort. Computational results for several case studies with known and unknown optimal schedules have been presented to assess the performance of the proposed technique. 相似文献
62.
A solution methodology has been developed for incompressible flow in general curvilinear co‐ordinates. Two staggered grids are used to discretize the physical domain. The first grid is a MAC quadrilateral mesh with pressure arranged at the centre and the Cartesian velocity components located at the middle of the sides of the mesh. The second grid is so displaced that its corners correspond to the centre of the first grid. In the second grid the pressure is placed at the corner of the first grid. The discretized mass and momentum conservation equations are derived on a control volume. The two pressure grid functions are coupled explicitly through the boundary conditions and implicitly through the velocity of the field. The introduction of these two grid functions avoids an averaging of pressure and velocity components when calculating terms that are generated in general curvilinear co‐ordinates. The SIMPLE calculation procedure is extended to the present curvilinear co‐ordinates with double grids. Application of the methodology is illustrated by calculation of well‐known external and internal problems: viscous flow over a circular cylinder, with Reynolds numbers ranging from 10 to 40, and lid‐driven flow in a cavity with inclined walls are examined. The numerical results are in close agreement with experimental results and other numerical data. Copyright © 2003 John Wiley & Sons, Ltd. 相似文献
63.
64.
A. Al-Badawi 《International Journal of Theoretical Physics》2007,46(6):1466-1470
We have obtained the exact solution of the equations of motion of a test particle near a thick domain walls. From the solution
it has been shown that the domain walls have repulsive gravitational fields. 相似文献
65.
66.
D. Sornette 《The European Physical Journal B - Condensed Matter and Complex Systems》1998,3(1):125-137
We propose a formulation of the term structure of interest rates in which the forward curve is seen as the deformation of
a string. We derive the general condition that the partial differential equations governing the motion of such string must
obey in order to account for the condition of absence of arbitrage opportunities. This condition takes a form similar to a
fluctuation-dissipation theorem, albeit on the same quantity (the forward rate), linking the bias to the covariance of variation
fluctuations. We provide the general structure of the models that obey this constraint in the framework of stochastic partial
(possibly non-linear) differential equations. We derive the general solution for the pricing and hedging of interest rate
derivatives within this framework, albeit for the linear case (we also provide in the appendix a simple and intuitive derivation
of the standard European option problem). We also show how the “string” formulation simplifies into a standard N-factor model under a Galerkin approximation.
Received: 30 January 1998 / Revised: 12 February 1998 / Accepted: 16 February 1998 相似文献
67.
A linear three‐dimensional hydrodynamical numerical model, with the application of the Galerkin Method for the vertical dependence, is here presented. The spherical coordinate system is used, in order to allow large‐scale simulations. The equations and mathematical development of the model are shown in detail, together with the boundary and initial conditions, and the sequence of equations' solution. The model is applied to the South Atlantic Ocean, for estimating typical seasonal circulations, and the results are summarized in maps of currents at surface and 1000 m depth, and in transport values of the Brazil Current between 30°S and 40°S. Copyright © 2002 John Wiley & Sons, Ltd. 相似文献
68.
James B. Hartle 《International Journal of Theoretical Physics》2006,45(8):1390-1396
Familiar quantum mechanics assumes a fixed spacetime geometry. Quantummechanics must therefore be generalized for quantum gravity where spacetime geometry is not fixed but rather a quantum variable. This extended abstract sketches a fully fourdimensional generalized quantum mechnics of cosmological spacetime geometries that is one such generalization.This contribution to the proceedings of the Glafka Conference is an extended abstract of the author's talk there. More details can be found in the references cited at the end of the abstract expecially (Hartle, 1995). 相似文献
69.
基于专家动态权重的群组AHP交互式决策方法 总被引:2,自引:0,他引:2
为了能在群组决策中得到更为客观和准确的决策结果,在把专家权重划分为静态权重和动态权重的基础上,研究了在交互式决策中专家动态权重的确定方法,给出了共识度的一个定义.在此基础上,研究了群组AHP交互式决策方法中的一致性和相容性检验,给出了基于专家动态权重的群组AHP交互式决策方法流程,最后用一个示例说明了该方法的应用步骤. 相似文献
70.