Squeeze-flow and vane rheometry of a gas–liquid foam

The rheology and slip of a dry shaving foam are investigated using squeeze-flow and rotating-vane methods. Constant-force squeeze flow between planar surfaces is used to study the effect of surface roughness on slip and to obtain the yield stress. Non-slip vane measurements are used to obtain the linear shear viscosity and elasticity at small strains, and the yield stress and strain at large strains. Data are compared with the small-strain Maxwell and Kelvin–Voigt linear-viscoelastic models. An apparent dependence of the yield stress and elasticity on the rotational speed of the vane is shown to result from time-dependent rheological parameters as the foam ages. The effect of viscosity in the pre-yield region may give an erroneous identification of yield.     

Preparation of well-dispersed magnetorheological fluids and effect of dispersion on their magnetorheological properties

In this work, we describe methods for the preparation of suspensions of micron-sized iron particles grafted with different surfactants. The aim is to obtain well-dispersed magnetorheological (MR) fluids. The effectiveness of the surfactants as dispersants was analyzed quantitatively by means of rheological measurements. With this objective, the viscosity of the suspensions was measured, and the results were compared with the prediction of the Batchelor’s formula (Batchelor, J Fluid Mech 83:97–117, 1977). The effect of dispersion on the MR properties of the suspensions was also studied. It was found that the quality of the dispersion of a suspension does not have an important effect on the magnitude of the field-induced yield stress but does on the change of viscosity induced by the field. It was also found that the transition from the solid-like state to the liquid-like one happens very smoothly for well-dispersed suspensions, contrarily to the abrupt transition for poorly dispersed suspensions.     

A SIMPLIFIED CALCULATING METHOD OF NONLINEAR FREQUENCY OF CABLE NET UNDER MEAN WIND LOAD

The cable net supported glass curtain wallas the most advanced technique in dot point supported glass curtain wall, is widely used in China. Because of its large deflection and high nonlinearity under wind load, the dynamic performance of the cable net is greatly different from that of the conventional linear structures. The continuous membrane theory is used to construct the nonlinear vibration differential equation of the cable net, and the harmonic balance method is used to solve the analytic formula of the nonlinear frequency. In order to verify the accuracy of the above analytic formula, the results of the formula and the nonlinear FEM time-history method are compared and found to be in good agreement. Furthermore, the nonlinear vibration differential equation and the nonlinear frequency obtained in this paper are the basis for the wind-induced response analysis of a cable net under fluctuating wind load.     

Calcul à la rupture en présence d'un écoulement : formulation cinématique avec un champ de pression approchéYield design formulation for porous media subjected to flow,using approximate pressure field

We attempt here to use the kinematic method of yield design in the case of a porous medium subjected to flow (with or without free surface), without looking for the exact solution of the pressure field. The method proposed here is based on the use of approximate pressure fields. In this paper, we show how, under different conditions concerning the yield criterion and the velocity field, the use of such approximate fields allows one to obtain a necessary condition for stability without having to find the real pressure field. To cite this article: A. Corfdir, C. R. Mecanique 334 (2006).     

Age dependence of the drag force in an aqueous foam

The drag force on a sphere moving through an aqueous foam is measured as the foam ages. After an initial period, the steady-state drag decreases with age T as T ^{−0.54±0.14}. As the mean bubble size R in the foam coarsens as T ^0.5, this implies that the drag force scales as The transient buildup of the force when the sphere starts to move is described by a single exponential approach to the steady-state drag while its relaxation when the motion stops is described by the sum of three exponential relaxations. This is as for fresh foam, but the coefficients and time constants vary systematically with age. For the most part, these quantities also show a power law scaling with T. The age dependence of the quantities determined in this study is discussed in terms of the mean bubble size.     

Proximal point algorithm with errors for generalized strongly nonlinear quasivariational inclusions

I.IntroductionLetHbeaHibertspaceendowedwithanorm11'11andaninnerproduct',.)andC(H)bethefamilyofallnonemptycompactsubsetsofH.LetT,A:H~C(H)besetvaluedmappings,g:H~Hbeasingle-valuedmappingand9:HxH~RU{ ac}besuchthatforeachfixedyeH,9.,y):H~RUt co}isaproperconvexlowersemicontinuousfunctiononHandg(H)ndomag'Y)#oforeachyeH,ThentheproblemoffindingxeH,ueT(x)andveA(x)suchthatg(x)edomag',x)and(u~v,y~g(x))39(g(x)'x)~9(y'x)(VYeH)(l.l)iscalledthegeneralizedstronglynonlinearquasivariationalinclusio…     

BEST APPROXIMATION THEOREM FOR SET-VALUED MAPPINGSWITHOUT CONVEX VELUES AND CONTINUITY

I.Introduction'In1969,KyFanl[Iprovedthefollowingwell-knownresultsonbestapproximation.Theorem1.1LetXbeanonemptycompactconvexsubsetofalocallyconvextopologicalvectorspaceEandf:X~Ebeacontinuousmapping.TheneitherfhasafixedpointinX,orthereexistapointyo6XandacontinuousseminormponEsucllthat0相似文献   

GPS技术在金川露天矿边坡变形监测中的应用

本文结合金川露天矿边坡变形GPS监测研究，主要论述监测基点的选择，基点WGS-84坐标的确定，变形监测网的布设，GPS数据采集、处理和质量，坐标转换的实施等，给出反演推出的若干四等三角点及其它控制点的变形数据，这些数据和造成变形的物理成因符合得很好，最后概括出GPS技术应用于变形观测的若干优点。     

ON THE EXISTENCE AND STABILITY OF SOLUTION FOR SEMI－HOMOGENEOUS BOUNDARY VALUE PROBLEM

ＯＮＴＨＥＥＸＩＳＴＥＮＣＥＡＮＤＳＴＡＢＩＬＩＴＹＯＦＳＯＬＵＴＩＯＮＦＯＲＳＥＭＩ－ＨＯＭＯＧＥＮＥＯＵＳＢＯＵＮＤＡＲＹＶＡＬＵＥＰＲＯＢＬＥＭＤｏｎｇＱｉｎｘｉ（董勤喜）;ＨｕａｎｇＸｉａｎｋａｉ（黄先开）（ＲｅｃｅｉｖｅｄＪｕｌｙ．４．１９...     

硫醇和硫醚的沸点与分子结构之间关系的拓扑化学研究

根据分子拓扑学原理, 用染色因子标识原子性质的差异, 发展了一种适用于含原子分子体系结构性能关系研究的新方法。据此探讨了硫醇和硫醚的沸点与分子结构之间的关系, 提出一个既能合理表征结构性能关系, 又能预测沸点的定量关系式。