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971.
Rinaldo M. Colombo Massimiliano D. Rosini 《Mathematical Methods in the Applied Sciences》2005,28(13):1553-1567
We present a model for the flow of pedestrians that describes features typical of this flow, such as the fall due to panic in the outflow of people through a door. The mathematical techniques essentially depend on the use of non‐classical shocks in scalar conservation laws. Copyright © 2005 John Wiley & Sons, Ltd. 相似文献
972.
This work deals with a free boundary identification problem in a steady viscoplastic flow. We provide a novel identification model based on a non-linear optimization. The fluid motion is governed by the incompressible Norton–Hoff model coupled with the heat equation. The viscosity of the fluid is modeled by the non-linear Arrhenius law. Our point of view is to treat the problem as a shape sensitivity of a cost functional formulated on the free boundary and governed by the normal component of the velocity of the flow. We analyze the mathematical statement of the forward problem. The equations related to the free boundary are simplified. Various properties of this optimization are proved. Since the state of Norton–Hoff model is not regular enough we introduce a parameter penalization. The shape gradient of the considered cost functional is given in the strong sense up to the parameter of penalization. We supply the expression of the shape gradient in a weak sense. 相似文献
973.
The effect of the nonparallelism of the boundary layer flow over a flat plate on its stability characteristics has been investigated
by several authors, and it was claimed that the results of the theoretical calculations are already in good agreement with
the experimental observations. However, this is not true. In this paper, this problem is reinvestigated, using two different
methods. It is found that within the framework of linear theory, the theoretical results are in fact not in good agreement
with the experimental observations. To settle this problem, nonlinear effect must be taken into consideration.
Projects Supported by the Science Fund of the Chinese Academy of Sciences 相似文献
974.
975.
D. Gabai 《Commentarii Mathematici Helvetici》2000,75(1):109-124
A -injective closed surface in an orientable 3-manifold with a tangentially smooth, transversely C
0 taut foliation can be homotoped to an immersed surface which is either transverse to the foliation except at isolated saddle
tangencies or mapped into a leaf.
Received: November 11, 1997 相似文献
976.
Commercial use of membrane adsorbers in the biotechnology industry is increasing. Here the system time lag created by membrane adsorber peripherals and the membrane adsorber flow distribution headers has been modeled using an anion exchange membrane and bovine serum albumin (BSA). The system time lag was modeled as a zero order and first order time lag. The zero and first order time lags have been removed from the breakthrough curve. The method used does not involve fitting a mathematical expression to the breakthrough curve. Further no assumptions are made regarding the shape of the breakthrough curve in the absence of the time lag. The method has been used to calculate the Langmuir isotherm parameters.The membrane capacity was found to be twice as large as the capacity determined after removal of the time lag. The Langmuir constant was five times as large for the system without accounting for the time lag. Errors in fitting isotherm parameters can significantly impact frontal analysis and membrane adsorber scale-up. The Langmuir isotherm calculated under dynamic conditions with the system time lag removed, was in agreement with the static adsorption isotherm. 相似文献
977.
This article presents solutions for the transient heat and moisture transport due to both disk heat source and cylindrical
heat source buried in an unsaturated half space. The solutions are presented in Hankel–Laplace transform domain and in dimensionless
style. Coupled effect of thermally driven moisture transport is especially investigated because of its importance to alter
the flow field in low-permeability medium. Parametric study has been performed to assess the effects of five independent dimensionless
parameters on flow field. The stability and accuracy of the present solutions are demonstrated from the comparison between
the results obtained from these solutions and those by using a well-established finite element code CODE_BRIGHT. Despite the
simplified assumptions required in order to obtain analytical solutions in Hankel–Laplace transform domain, the results incorporate
the main mechanisms involved in the coupled thermo-hydraulic (T-H) problem, and they may be eventually used for validation
purposes. 相似文献
978.
979.
The shear-induced isotropic-to-nematic phase transition of side chain liquid-crystalline polymers is studied theoretically. A modification of the previous models of main-chain liquid crystals to the case of side chain liquid-crystalline polymers is proposed. Orientational and rheological properties of the model are studied in plane-shear flow. Predictions of the present model agree qualitatively with experimental results (Pujolle-Robic, Noirez in Nature 409:167, 2001). 相似文献
980.