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41.
D. G. Pavlou 《Computational Mechanics》2002,29(3):254-264
Green's function is obtained for the infinite bimaterial elastic solid, containing an internal circular interface crack,
loaded by a unit tangential co-axial circular source. An axisymmetric direct boundary integral equation (BIE) is used for
the analysis of a finite bimaterial axisymmetric body containing an internal circular interface crack and a finite homogeneous
cracked cylinder, both under torsional loading. Using the proposed technique, no discretization of the crack surface is necessary.
Numerical results for both examples as obtained by the proposed method are presented and discussed.
Received: 29 October 2001 / Accepted: 29 May 2002 相似文献
42.
《Drying Technology》2007,25(7):1237-1242
Rewarming of fruits and vegetables after cooling is characterized by heat and mass transfer processes, which leads commonly to condensation of water on the produce surface at temperatures below the dew point. This effect may affect the produce quality due to microbial growth at unfavorable environmental conditions. The amount of condensed water is a function of the produce surface temperature and of the surrounding conditions as air temperature, air humidity, and air flow. Under practical conditions, both the warming and the condensation are strongly affected by the packaging system used. Depending on the flow conditions close to the produce surface, parameters of heat and mass transfer under laboratory conditions were measured. A mathematical model was developed for the determination of the amount of condensed water on fruit surfaces, its reevaporation, and its total dwell time dependent on the environment air conditions. The model describes the heat and mass transfer processes on single fruits. The process of diffusion of humidity in air and proceed of surface temperature is the basis for the model. 相似文献
43.
The aim of this study was to evaluate the effects of paste properties on residence time during drying in a spouted bed dryer with inert bodies. The effect of paste solids content, surface tension, and viscosity on the residence time distribution and the mean residence times were studied using factorial experimental designs. The inert bodies used were glass and polyethylene beads. The mean residence times varied from 13.6 to 16.3 and 12.2 to 17.7 min for drying on glass and polyethylene beads, respectively. The analysis of variance showed that mean residence times significantly depended on solids content and surface tension for glass beads and also on viscosity for polyethylene beads. The residence time distributions for all conditions studied fitted well to the perfect mixing cell when applying the continuous stirred vessels in series model analysis. The powder density, flowability, and particle size depended on paste properties and inert type. 相似文献
44.
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46.
W. Ming F. Melis R. D. van de Grampel L. van Ravenstein M. Tian R. van der Linde 《Progress in Organic Coatings》2003,48(2-4):316-321
Self-stratification strategy can be used to prepare films in which both bulk and surface properties can be optimized. By using this approach, only a very small quantity of fluorinated species is needed to generate a surface with low surface energy. When cross-linking is involved during film formation, we are dealing with a competition behavior between the diffusion of fluorinated species and the formation of cross-linked network. In this study low surface energy polymeric films were prepared on the basis of partially fluorinated polyisocyanates, in combination with hydroxyl-end-capped three-armed solventless liquid oligoesters and modified hyperbranched polyesters. At a fluorine concentration of only 0.5 wt.%, contact angles of water and hexadecane can reach 120° and 80°, respectively. A surface energy as low as 10–15 mN/m can be obtained upon the addition of less than 1 wt.% of fluorine in the films. It was shown, from real time ATR-FTIR and contact angle measurements, that the curing temperatures demonstrated significant effects on the cross-linking rate as well as on the wettability of the films. 相似文献
47.
Experimental investigation of natural convection from a horizontal ice surface melting in pure water
Byung-Ha Kim Seung-Hwan Cho Kap-Jong Riu 《Journal of Mechanical Science and Technology》1991,5(2):93-103
A study on natural convection from a horizontal ice surface melting in pure water was conducted experimentally for the ambient
water temperature from 2▿C to 10°C. Natural convection flow around upward-or downward-facing horizontal ice plate was divided
into three regions according to the temperature variation of ambient water. The flow patterns of three regions were no flow,
two-dimensional steady laminar flow and unsteady flow. Mean Nusselt number for the upward-facing surface had its maximum value
at about 3°C of ambient water temperature. However, in the case of the downward-facing surface it increased as the ambient
water temperature increased. 相似文献
48.
海湾战争中,“爱国者”导弹成功地拦截了“飞毛腿”导弹,给近程地对地战术导弹的作用、发展与装备方向提出了值得思考的问题。本文着重讨论在局部战争中,近程地对地战术导弹的作用、使用场合及其技术发展方向。 相似文献
49.
G. Agostinelli A. Delabie P. Vitanov Z. Alexieva H.F.W. Dekkers S. De Wolf G. Beaucarne 《Solar Energy Materials & Solar Cells》2006,90(18-19):3438-3443
Surface recombination velocities as low as 10 cm/s have been obtained by treated atomic layer deposition (ALD) of Al2O3 layers on p-type CZ silicon wafers. Low surface recombination is achieved by means of field induced surface passivation due to a high density of negative charges stored at the interface. In comparison to a diffused back surface field, an external field source allows for higher band bending, that is, a better performance. While this process yields state of the art results, it is not suited for large-scale production. Preliminary results on an industrially viable, alternative process based on a pseudo-binary system containing Al2O3 are presented, too. With this process, surface recombination velocities of 500–1000 cm/s have been attained on mc-Si wafers. 相似文献
50.
A new curvature technique calculation for surface tension contribution in PLIC-VOF method 总被引:1,自引:0,他引:1
The volume of fluid (VOF) methods have been used for numerous numerical simulations. Among these techniques used to define
the moving interface, the piecewise linear interface reconstruction (PLIC-VOF) is one of the most accurate. A study of the
superficial tension impact on two-phase flow with free surface is presented. A new method based on direct staggered grid is
developped to include surface tension in PLIC-VOF. The new numerical curvature calculation method doesn't need smoothed colour
function and leads to less “spurious current”. This technique is applied to the calculus of surface tension force in the case
of the rise of air bubble in viscous liquid and the fall of liquid drop in the same liquid on free surface. Droplets, thin
layer and capillarity waves are observed after the free surface rupture for different Bond number. The influence of surface
tension calculus is then obvioused and when the drop hit the free surface, wavelets propagate toward the virtual boundaries
imposed. 相似文献