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1.
2.
Modeling and numerical simulations of the convective flows induced by the vibration of the monocrystal during crystal growth have been performed for two configurations simulating the Cz and FZ methods. This permitted to emphasize the role of different vibrational mechanisms in the formation of the average flows. It is shown that an appropriate combination of these mechanisms can be used to counteract the usual convective flows (buoyancy- and/or thermocapillary-driven) inherent to crystal growth processes from the liquid phase. While vibrational convection is rather complex due to these identified mechanisms, the new modeling used in the present paper opens up very promising perspectives to efficiently control heat and mass transfer during real industrial applications of crystal growth from the liquid phase. 相似文献
3.
Convective heat transfer from an array of small, cylindrical bodies of arbitrary shape in an unbounded, two-dimensional domain is a singular perturbation problem involving an infinite logarithmic expansion in the small parameter ε, representing the order of magnitude of the size of the bodies. Using the method of matched asymptotic expansions, we formulate a hybrid asymptotic-numerical method to solve for the dimensionless, steady-state temperature. We assume that the velocity field of the fluid surrounding the bodies is arbitrary but known. From our asymptotic solution for an arbitrary velocity field, we present the results for two special cases: a uniform flow field and a simple shear flow field. We demonstrate the asymptotic results of the hybrid method through a number of examples and, in a particular case, we compare these results to an exact analytical solution. 相似文献
4.
Jan Annaert Griselda Deelstra Michèle Vanmaele 《Insurance: Mathematics and Economics》2007,41(3):299-316
In this paper, we elaborate a formula for determining the optimal strike price for a bond put option, used to hedge a position in a bond. This strike price is optimal in the sense that it minimizes, for a given budget, either Value-at-Risk or Tail Value-at-Risk. Formulas are derived for both zero-coupon and coupon bonds, which can also be understood as a portfolio of bonds. These formulas are valid for any short rate model that implies an affine term structure model and in particular that implies a lognormal distribution of future zero-coupon bond prices. As an application, we focus on the Hull-White one-factor model, which is calibrated to a set of cap prices. We illustrate our procedure by hedging a Belgian government bond, and take into account the possibility of divergence between theoretical option prices and real option prices. This paper can be seen as an extension of the work of Ahn and co-workers [Ahn, D., Boudoukh, J., Richardson, M., Whitelaw, R., 1999. Optimal risk management using options. J. Financ. 54, 359-375], who consider the same problem for an investment in a share. 相似文献
5.
David J. Aitken Dominique Guillaume Henri-Philippe Husson Angle Chiaroni Claude Riche 《Journal of heterocyclic chemistry》1991,28(3):705-709
The title compound, containing a new heterocyclic skeleton, was identified by X-ray crystallography as the product of condensation of (R)-phenylglycinol with an excess of formaldehyde. The molecule adopts a rigid double twist-chair conformation in both solid and solution states. 相似文献
6.
Michèle Audin 《manuscripta mathematica》2007,124(4):533-550
In this paper, we investigate symplectic manifolds endowed with a Morse–Bott function with only two critical submanifolds,
one of which is Lagrangian while the other one is symplectic. 相似文献
7.
8.
C. Bréchignac Ph. Cahuzac F. Carlier C. Colliex M. de Frutos N. Kébaïli J. Le Roux A. Masson B. Yoon 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2003,24(1-3):265-268
We studied shape relaxation of nano-fractal islands,
during annealing, after their growth from antimony cluster
deposition on graphite surface. Annealing at
180°C shows evidence of an increase
of the fractal branch width with time followed by branch
fragmentation, without changing the fractal dimension. The time
evolution of the width of the arm suggests the surface
self-diffusion mechanism as the main relaxation process. With
Monte Carlo simulations, we confirmed the observed behavior.
Comparison is done with our previous results on fragmentation of
nano-fractal silver islands when impurity added to the incident
cluster promotes rapid fragmentation by surface self-diffusion
enhancement [1]. 相似文献
9.
Jan-Martin Heldt Michèle Salmain Gérard Jaouen 《Journal of organometallic chemistry》2004,689(25):4775-4782
The first poly(amidoamine) (PAMAM) dendrimers tethered with both (η5-cyclopentadienyl) rhenium tricarbonyl (CpRe(CO)3) units and polyethylene glycol (PEG) chains were prepared and characterized by combining NMR spectroscopy and Fourier-transform IR spectroscopy. Grafting of CpRe(CO)3 units was achieved by reductive amination of formyl-CpRe(CO)3 with the peripheral amines of generation 3 and 4 PAMAMs to yield dendrimers labeled with a variable number of CpRe(CO)3 units, ranging from 8 to 14 for PAMAM-G3 and 17-30 for PAMAM-G4. PEG chains of different lengths were then attached to some of the remaining peripheral amines, and their respective ability to improve the solubility of the metallodendrimers in aqueous buffered media was evaluated. These metallodendrimers represent new infrared probes designed to be coupled to immunological reagents for the amplification of the IR signal in carbonyl metallo immunoassay (CMIA). 相似文献
10.
The frequency or dispersion relation for the least‐squares mixed formulation of the shallow‐water equations is analysed. We consider the use of different approximation spaces corresponding to co‐located and staggered meshes, respectively. The study includes the effect of Coriolis, and the dispersion properties are compared analytically and graphically with those of the mixed Galerkin formulation. Numerical solutions of a test problem to simulate slow Rossby modes illustrate the theoretical results. Copyright © 2003 John Wiley & Sons, Ltd. 相似文献