Showing papers on "Elasticity (economics) published in 1991"
TL;DR: In this paper, a new contrast mechanism relies on variation in the surface elasticity of a carbon fiber and epoxy composite is used to reveal contrast between the two materials, and a lateral modulation mode is employed to highlight atomic steps in gold.
Abstract: Using a new mode of scanning, the force modulation mode, surfaces are imaged by the atomic force microscope. The new contrast mechanism relies on variation in the surface elasticity. The cross section of a carbon fibre and epoxy composite is imaged, showing contrast between the two materials. Surface elasticity variations across the cross section of the fibre are revealed. A lateral modulation mode is used to highlight atomic steps in gold.
491 citations
TL;DR: In this article, a rigorous solution of the spherical inclusion problem with remote uniform strain or stress and imperfect elastic spring-type interface conditions is presented, where the interface spring constants are expressed in terms of interphase elastic properties and thickness.
Abstract: A rigorous solution of the spherical inclusion problem with remote uniform strain or stress and imperfect elastic spring-type interface conditions is presented. In the case of thin elastic interphase, the interface spring constants are expressed in terms of interphase elastic properties and thickness
374 citations
TL;DR: Simultaneous measurements of stretch activated (SA) ion channel activity in the patch showed that the sensitivity of channels from different patches, although different when calculated as a function of applied pressure, was the same when calculated by nonlinear regression of images to a geometric model.
250 citations
Posted Content•
TL;DR: The authors examined the relationship between temporary terms of trade shocks and household saving in developing countries, and showed that private saving may rise or fall in response to a transitory terms-of-trade shock, depending on the values of the intertemporal elasticity of substitution and the intratemporal linear elasticity between traded and nontraded goods.
Abstract: This paper examines the relationship between temporary terms of trade shocks and household saving in developing countries. It is first shown that, from a theoretical standpoint, this relationship is ambiguous: private saving may rise or fall in response to a transitory terms of trade shock, depending on the values of the intertemporal elasticity of substitution and the intratemporal elasticity of substitution between traded and nontraded goods. Empirical estimates of these two parameters are obtained using data from a sample of 13 developing countries, and then used to draw implications for the response of private saving to transitory terms of trade shocks.
237 citations
TL;DR: In this article, the authors examine an important influence on the price-advertising tradeoff, the ratio of price and advertising elasticities, and stress the centrality of the elasticity in the tradeoff.
Abstract: The authors examine an important influence on the price-advertising tradeoff, the ratio of price and advertising elasticities. Their theoretical analysis stresses the centrality of the elasticity r...
201 citations
Patent•
13 Mar 1991
TL;DR: In this article, a polypropylene foam sheet having a smooth surface and a uniform cell structure and a density of at least 2.5 lbs/ft3 is prepared by extruding a mixture of a nucleating agent, a physical blowing agent and a polyethylene resin having a high melt strength and high melt elasticity.
Abstract: A thermoformable, rigid or semi-rigid polypropylene foam sheet having a smooth surface and a uniform cell structure and a density of at least 2.5 lbs/ft3 is prepared by extruding a mixture of a nucleating agent, a physical blowing agent and a polypropylene resin having a high melt strength and high melt elasticity.
152 citations
TL;DR: In this article, the applicability of Cosserat elasticity to cellular solids and fibrous composite materials is considered as well as the application of related generalized continuum theories.
Abstract: Continuum representations of micromechanical phenomena in structured materials are described, with emphasis on cellular solids. These phenomena are interpreted in light of Cosserat elasticity, a generalized continuum theory which admits degrees of freedom not present in classical elasticity. These are the rotation of points in the material, and a couple per unit area or couple stress. Experimental work in this area is reviewed, and other interpretation schemes are discussed. The applicability of Cosserat elasticity to cellular solids and fibrous composite materials is considered as is the application of related generalized continuum theories. New experimental results are presented for foam materials with negative Poisson's ratios.
125 citations
TL;DR: In this paper, Young's modulus of elasticity of organic drugs and excipients as determined by 3-point beam bending can be predicted from cohesive energy density, but the moduli are lower than expected from theory due to specimen effects or to temperature differences between the theoretical treatment and measurements made at room temperature.
118 citations
TL;DR: Using Fourier transform infrared spectroscopy, evidence is found of either helix formation or reorientation of preexisting helices when axial tension is applied to the spider silk fiber to suggest a possible molecular mechanism for the elasticity of spider silk fibers.
87 citations
15 Aug 1991
TL;DR: The paper by Wright contained an erroneous proof and Shinohara's paper did not make it clear that the definition had been changed, nor did it digress to explain the reason for the change and the status of the other results in Wright's original paper.
Abstract: The paper by Wright[Wri89] contained an erroneous proof. Motoki first discovered the problem and constructed a counter-example. When this was communicated to Shinohara, who was writing a paper[Shi90] that used the erroneous result, he found a new definition which let his proof go through. Shinohara's paper did not make it clear that the definition had been changed, nor did it digress to explain the reason for the change and the status of the other results in Wright's original paper. We now set this matter straight.
83 citations
TL;DR: In this article, an analytical inelastic treatment of the funnel flow was presented and an attempt was made to include the effect of elasticity in both flows and the combined effect is for the Couette correction to exhibit an initial decrease followed by a rapid increase which becomes less dramatic as the flow mode changes.
Abstract: Two distinct mechanisms are proposed for the flow of non-Newtonian fluids through abrupt contractions. The first is a quasi-radial flow which is argued to reflect at least qualitatively the flow characteristics at low strain rates. Depending on the rheological properties of the fluid, the second mechanism, referred to as funnel flow, may well be preferred at higher rates of strain. The change from the first to the second flow mechanism is often seen to occur experimentally with the appearance of a so-called ‘lip’ vortex. An approximate analytical inelastic treatment of the funnel flow was presented in an earlier paper. A similar treatment is now offered for the quasi-radial flow and, in addition, an attempt is made to include the effect of elasticity in both flows. Particular attention is placed on the influence of shear viscosity, elasticity (through the first normal stress difference in shear) and extensional viscosity. The analyses suggest that the effects of elasticity and extensional viscosity are opposite, the former resulting for example in a decreased Couette correction while the latter causes the Couette correction to increase. The reduction is seen to be a consequence of the stress boundary conditions which result from the way in which the Couette correction is defined. For realistic fluid parameters the combined effect is for the Couette correction to exhibit an initial decrease followed by a rapid increase which becomes less dramatic as the flow mode changes. As far as the generation and growth of vortices are concerned it would appear that elasticity may enhance the size of the salient corner vortex but again the extensional viscosity has the opposite effect. For funnel flow, in which a recirculating zone is assumed to exist up to the lip of the contraction, vortex growth appears to be almost exclusively dominated by extensional viscosity.
TL;DR: The role played by particle-particle interactions in determining the macroscopic properties of colloidal dispersions such as viscosity, viscoelasticity and elasticity was examined in this paper.
Abstract: The use of various modern techniques to examine particle–particle interactions in concentrated colloidal dispersions is reviewed. The analogy between colloidal dispersions and molecular fluids is drawn and the conditions for the formation of colloidal crystals discussed. The latter part of the article examines the role played by particle–particle interactions in determining the macroscopic properties of colloidal dispersions such as viscosity, viscoelasticity and elasticity.
TL;DR: In this article, the stability of wet foams of fatty acid solutions (n-pentanoic to n-decanoic acid) in 0.005 N HCl was studied.
TL;DR: In this paper, the curvature elastic properties of monolayers of diblock copolymers adsorbed at the interface of two incompatible solvents which are also selective for the two blocks were studied.
Abstract: We study the curvature elastic properties of monolayers of diblock copolymers adsorbed at the interface of two incompatible solvents which are also selective solvents for the two blocks. At saturation, the interfacial free energy is minimized with respect to contributions from the chain conformation free energy, the interfacial tension, and the two‐dimensional translational entropy of the chains. For a curved interface, this minimization leads naturally to curvature elasticity. The three elastic coefficients, the spontaneous radius of curvature, the bending modulus, and the Gaussian bending modulus, as functions of the molecular weights, the interfacial tension, the interaction parameters, etc., are obtained for a number of cases. Our study employs the theory for grafted chains recently developed by Milner et al. to obtain the chain conformation free energy which takes into account the nonuniformity of the chain‐end distribution. This improvement not only affects the overall prefactor of the free energy but it changes the relative values of the three elastic coefficients as well. We consider the cases of both a swollen monolayer and a monolayer consisting of a melt of copolymer chains, as well as an interesting case where one of the blocks is in the swollen condition and the other block is in the melt condition. Because the chains in the melt and the swollen conditions have distinctively different scaling behaviors, the mixed case displays some features that are different from either the swollen and the melt cases.
TL;DR: In this paper, the problem of linear elasticity for an infinite number of non-intersecting spherical and ellipsoidal inhomogeneities is attacked, where the Eshelby equivalent inclusion method is used.
Journal Article•
TL;DR: Two preconditioning techniques for the numerical solution of linear elasticity problems are described and studied and the efficiency and robustness of the described techniques are illustrated by numerical experiments.
Journal Article•
TL;DR: In this article, the bending elasticity constant of the monolayer was measured by ellipsometry in a Winsor system with a range of alkanes, and the authors investigated the multiphase behavior of the third phase in terms of the differing extents of oil penetration into the surfactant chain region.
Abstract: In systems containing AOT + aqueous NaCl + normal alkane, the change of the microemulsion type from oil-in-water to water-in-oil through a surfactant-rich phase can be effected by increasing the aqueous phase salt concentration. We have investigated the multiphase behaviour (in Winsor systems) for a range of alkanes. The low oil-water interfacial tensions enable us to measure the bending elasticity constant K of the monolayer by ellipsometry. Values of K are independent of salt concentration but decrease with increasing alkane chain length. This is discussed in terms of the differing extents of oil penetration into the surfactant chain region and its consequences on the structure of the third phase.
TL;DR: In this paper, a constitutive model for the nonlinear elastic behavior of isotropic low-density open-cell foams with three-dimensional structure is formulated in terms of a strain energy function.
Abstract: A constitutive model for the nonlinear elastic behavior of isotropic low-density open-cell foams with three-dimensional structure is formulated in terms of a strain energy function. The theory is based on micromechanical analysis of an idealized tetrahedral unit cell of arbitrary orientation that contains four half-struts joining at equal angles
TL;DR: In this article, the apparent energy density, which is the quasiconvexification of the two-well potential, is computed and some minimum energy and uniqueness theorems are proved.
Abstract: The apparent energy density, which is the quasiconvexification of the two-well potential, is computed. For the version of elasticity theory based on the apparent energy density, certain minimum-energy and uniqueness theorems are proved
TL;DR: In this article, the authors estimate multicentric density and land value gradients for the years 1973 and 1985, and then explore how housing producers respond to changes in land prices, by calculating a land-capital substitution elasticity.
01 Jun 1991
TL;DR: In this paper, the stiffness distribution in XTH-2 cells was compared with the organization of F-actin and microtubules, but no correlation to microtubule arrangement was found.
Abstract: The scanning acoustic microscope (SAM) allows one to measure mechanical parameters of living cells with high lateral resolution. By analyzing single acoustic images’ sound attenuation and sound velocity, the latter corresponding to stiffness (elasticity) of the cortical cytoplasm can be determined. In this study, measurements of stiffness distribution in XTH-2 cells were compared with the organization of F-actin and microtubules. Single XTH-2 cells exhibit relatively high stiffness at the free margins; toward the cell center this value decreases and reaches a sudden minimum where the slope of the surface topography enlargens at the margin of the dome-shaped cell center. The steepness of the increase in slope is linearly related to the decrease in sound velocity at this site. Thus, a significant determinant of cell shape is paralleled by an alteration of stiffness. In the most central parts, no interferences could be distinguished, therefore, this region had to be excluded from the calculations. Stiffness distribution roughly coincided with the distribution of F-actin, but no correlation to microtubule arrangement was found.
TL;DR: On a etudie le module d'young, le module de cisaillement and le coefficient de poisson de Si 3 N 4, SiC, Al 2 O 3 et de la zircone TZP a l'aide d'une technique de resonance jusqu'a 1400°C as mentioned in this paper.
Abstract: On a etudie le module d'young, le module de cisaillement et le coefficient de poisson de Si 3 N 4 , SiC, Al 2 O 3 et de la zircone TZP a l'aide d'une technique de resonance jusqu'a 1400°C
TL;DR: In this article, a transfer from the three-dimensional theory of elasticity in a thin rod to the problem of the theory of beams is made, which differs from the problems of plates discussed in /1, 2/ in that the dimensions are reduced, during the passage to the limit, by two.
Journal Article•