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51.
G. Doucas M. F. Kimmitt Th. Kormann G. Korschinek C. Wallner 《International Journal of Infrared and Millimeter Waves》2003,24(6):829-845
Spontaneous Smith-Purcell radiation at wavelengths of 100 and 220m has been observed. The angles of observation were 17° and 28° and the electron beam energies 1.9 and 1.56MeV, respectively. The radiated power was about 320nW at 17° and 92nW at 28°. These values are in reasonable agreement with what is theoretically expected if the emission process is due to the acceleration of image charges induced on the grating surface by the electrons of the beam. 相似文献
52.
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54.
This paper presents a local domain‐free discretization (DFD) method for the simulation of unsteady flows over moving bodies governed by the incompressible Navier–Stokes equations. The discretization strategy of DFD is that the discrete form of partial differential equations at an interior point may involve some points outside the solution domain. All the mesh points are classified as interior points, exterior dependent points and exterior independent points. The functional values at the exterior dependent points are updated at each time step by the approximate form of solution near the boundary. When the body is moving, only the status of points is changed and the mesh can stay fixed. The issue of ‘freshly cleared nodes/cells’ encountered in usual sharp interface methods does not pose any particular difficulty in the presented method. The Galerkin finite‐element approximation is used for spatial discretization, and the discrete equations are integrated in time via a dual‐time‐stepping scheme based on artificial compressibility. In order to validate the present method for moving‐boundary flow problems, two groups of flow phenomena have been simulated: (1) flows over a fixed circular cylinder, a harmonic in‐line oscillating cylinder in fluid at rest and a transversely oscillating cylinder in uniform flow; (2) flows over a pure pitching airfoil, a heaving–pitching airfoil and a deforming airfoil. The predictions show good agreement with the published numerical results or experimental data. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献
55.
Kim Soo-Gil Lee Hong-Seok Kim Kyu-Tae Kim Eun-Soo Lee Byoungho 《Optical and Quantum Electronics》2000,32(3):419-430
We suggested a new non-mechanical angular multiplexed holographic memory system using a moving window, which was fabricated by controlling the pixels of a liquid crystal display (LCD) electronically. If we use light passed through the window left and right, and up and down, each window makes a reference wave with a different incidence angle and we can store angular-multiplexed holograms. The feasibility of the proposed method was demonstrated through optical experiments and its crosstalk noise analysis was also presented. 相似文献
56.
Simulated moving bed (SMB) chromatography combines high productivity and high purities with reduced buffer consumption. We have developed a laboratory scale single column SMB (SC-SMB) unit with all four separation zones in one column. Distributors embedded within the chromatographic medium allow introduction and withdrawal of liquid between the zones. This single column unit exhibits homogenous packing in all zones, reduced headspace, less complex tubing, fewer valves, and almost undisturbed plug flow between the separation zones. The separation performance of the column was investigated with two different binary model mixtures. Furthermore, the SC-SMB unit is operated with a modified AKTA Explorer workstation, which has been specifically developed for the handling of biological fluids. 相似文献
57.
Summary The aim of this paper is to propose new selection criteria for the orders of selfexciting threshold autoregressive (SETAR)
models. These criteria use bootstrap methodology; they are based on a weighted mean of the apparent error rate in the sample
and the average error rate obtained from bootstrap samples not containing the point being predicted. These new criteria are
compared with the traditional ones based on the Akaike information criterion (AIC). A simulation study and an example on a
real data set end the paper. 相似文献
58.
1IntroductionThegeometricphaseplaysanimportantroleinunderstandingsomeoftheoutstandingenigmasofquantummechanics,andithaspaidmu... 相似文献
59.
A parallel, finite element method is presented for the computation of three‐dimensional, free‐surface flows where surface tension effects are significant. The method employs an unstructured tetrahedral mesh, a front‐tracking arbitrary Lagrangian–Eulerian formulation, and fully implicit time integration. Interior mesh motion is accomplished via pseudo‐solid mesh deformation. Surface tension effects are incorporated directly into the momentum equation boundary conditions using surface identities that circumvent the need to compute second derivatives of the surface shape, resulting in a robust representation of capillary phenomena. Sample results are shown for the viscous sintering of glassy ceramic particles. The most serious performance issue is error arising from mesh distortion when boundary motion is significant. This effect can be severe enough to stop the calculations; some simple strategies for improving performance are tested. Copyright © 2001 John Wiley & Sons, Ltd. 相似文献
60.
K. Suresh Chandra P. Koteeswaran 《Annals of the Institute of Statistical Mathematics》1986,38(1):311-318
Summary In this paper we consider the superimposed processZ generated by two independent subcritical Galton-Watson processesX
1 andX
2, with immigration, by the relationZ=X
1
+X
2. The seemingly second order autoregressive relation, that is identified inZ, is exploted towards proposing CAN estimators for the parameters ofZ,X
1 andX
2, based on only a partial realisation ofZ, using time series techniques. The results of this paper are motivated by a time series approach for studying specific branching
processes due to Venkataraman (1982,Adv. Appl. Prob.,14, 1–20). 相似文献