Showing papers on "Elasticity (economics) published in 1996"
Book•
01 Jan 1996TL;DR: The Lekhnitskii Formalism as discussed by the authors is a generalization of the Stroh Formulism for linear anisotropic elasticity matrices with an elliptic boundary.
Abstract: 1. Matrix Algebra 2. Linear Anisotropic Elastic Materials 3. Antiplane Deformations 4. The Lekhnitskii Formalism 5. The Stroh Formalism 6. The Structures and Identities of the Elasticity Matrices 7. Transformation of the Elasticity Matrices and Dual Coordinate Systems 8. Green's Functions for Infinite Space, Half-space, and Composite Space 9. Particular Solutions, Stress Singularities, and Stress Decay 10. Anisotropic Matrials with an Elliptic Boundary 11. Anisotropic Media with a Crack or a Rigid Line Inclusion 12. Steady State Motion and Surface Waves 13. Degenerate and Near Degenerate Materials 14. Generalization of the Stroh Formulism 15. Three-Dimensionsal Deformations
1,250 citations
TL;DR: The elastic constants of GaN have been determined using Brillouin scattering; in GPa they are: C11=390, C33=398, C44=105, C66=123, C12=145, and C13=106.
Abstract: The elastic constants of GaN have been determined using Brillouin scattering; in GPa they are: C11=390, C33=398, C44=105, C66=123, C12=145, and C13=106. Our values differ substantially from those quoted in the literature which were obtained from the determination of mean square displacement of atoms measured by x‐ray diffraction.
554 citations
357 citations
TL;DR: A new method to reconstruct the elastic modulus of soft tissue subjected to an external static compression is presented and it is shown that the method converges within a few iterations and that strain images artifacts are significantly reduced after the resolution of the inverse problem.
Abstract: A new method to reconstruct the elastic modulus of soft tissue subjected to an external static compression is presented. In this approach the Newton-Raphson method is used to vary a finite element (FE) model of the elasticity equations to fit, in a least squared sense, a set of axial tissue displacement fields estimated using a correlation technique applied to ultrasound signals. The ill-conditioning of the Hessian matrix is eliminated using the Tikhonov regularization technique. This regularization provides a compromise between fidelity to the observed data and a priori information of the solution. Using an echographic image formation model, it is shown that the method converges within a few iterations (8-10) and that strain images artifacts which are common in elastography are significantly reduced after the resolution of the inverse problem.
345 citations
TL;DR: This paper studied the relationship between product category characteristics and average brand promotional elasticity within the category and presented a framework for understanding these relations, which can be used to understand the relationship among product categories.
Abstract: The authors study the relationships between product category characteristics and average brand promotional elasticity within the category. They present a framework for understanding these relations...
345 citations
TL;DR: In this paper, simple 1-D ultrasound elasticity measurements were performed on muscle and liver and compared with independent and established mechanical measurements to investigate both the accuracy and consistency of ultrasound measurements.
Abstract: Ultrasound elasticity imaging is a promising method that may eventually allow early detection of many tissue pathologies. However, before elasticity imaging can be applied to its numerous potential clinical applications, the quantitative accuracy of tissue elasticity measurements must be established. Simple 1-D ultrasound elasticity measurements were performed on muscle and liver and compared with independent and established mechanical measurements to investigate both the accuracy and consistency of ultrasound elasticity measurements. In addition, some interesting properties of soft tissue and aspects of the measurement process which should be considered in elasticity measurements are discussed.
338 citations
TL;DR: This chapter describes various types of stress employed to cause tissue deformation and MRI methods that are used to measure the resulting strain, and it outlines some of the common algorithms used to extract metrics reflecting tissue elasticity.
Abstract: There has been a longstanding scientific interest in the noninvasive evaluation of the biomechanical properties of soft tissues. Magnetic resonance imaging (MRI) has emerged as a useful tool for assessing tissue response to mechanical loading. In this chapter, we briefly summarize the theoretical basis of elasticity imaging. We describe various types of stress employed to cause tissue deformation and MRI methods that are used to measure the resulting strain, and we outline some of the common algorithms used to extract metrics reflecting tissue elasticity. 4.
304 citations
TL;DR: In a comparison of elasticity matrices for 84 species of plants, the authors showed that the importance of recruitment from seed, stasis, and growth varies systematically between the groups se- melparous herbs, iteroparoas herbs of open habitats, forest herbs, shrubs, and trees.
Abstract: Population projection (Lefleovitch) matrices are now a standard method for quantifying and ana- lyzing the demography and population dynamics of plants. Elasticity analysis of such a matrix indicates the relative effect on the population growth rate (A) of small changes to matrix elements representing different transitions in the life cycle. In a comparison of elasticity matrices for 84 species of plants we show that the rel- ative importance of recruitment from seed (measured by composite elasticity F), stasis (measured by compos- ite elasticity L), and growth (measured by composite elasticity G) varies systematically between the groups se- melparous herbs, iteroparoas herbs of open habitats, forest herbs, shrubs, and trees. We discuss how this result might be used to construct rules of thumb useful in plant conservation. By looking in detaa at how A covarles with the composite elasticities F, I, and G among 16populations of the semelparoas herb Cirsium vulgare and among 15 populations of the rare iteroparoas herb Pedicularis furbishiae, we show that a naive interpretation of elasticities can give a misleading prescription for management. Instead, we show that elasticity analysis supports management prescriptions based upon the successional status of a species or upon its response to disturbance.
297 citations
TL;DR: A literature review of a variety of methods for the estimation of tissue elasticity that have been reported in the literature in the past 15 years, and of data on the elastic properties of soft tissues.
296 citations
TL;DR: Harmonic and Cartan decompositions were used by as mentioned in this paper to prove that there are eight symmetry classes of elasticity tensors, and their results in apparent contradiction with this conclusion are discussed in a short history of the problem.
Abstract: Harmonic and Cartan decompositions are used to prove that there are eight symmetry classes of elasticity tensors. Recent results in apparent contradiction with this conclusion are discussed in a short history of the problem.
235 citations
Book•
01 Dec 1996
TL;DR: In this paper, a histogram-based histogram technique is used to calculate forces, elasticity and adhesion viscosity at the nanometer-scale, and a comparison of friction force microscopy microscopy lubrication studies by friction forces microscopy nano-scale modifications wear mechanisms is presented.
Abstract: Part 1 Instrumental aspects: deflection sensors force sensors and probing tips implementation into different environments calibration procedures force vs. distance curves elasticity and adhesion measurements determination of friction coefficients 2-d histogram technique. Part 2 Theoretical concepts: forces, elasticity and adhesion viscosity Amontons laws adhesion model atomic-scale stick-slip. Part 3 Tribological experiments on the nanometer-scale: contrast mechanisms of friction force microscopy lubrication studies by friction force microscopy nanometer-scale modifications wear mechanisms conclusions and outlook.
TL;DR: In this article, the influence of an unjustifiable factor on one's judgment depends on the presence of elasticity (ambiguity) in justifiable factors; the influence will be greater if there is elasticity than if there are not.
TL;DR: In this paper, the authors used a regression model to estimate both price and income elasticity in the United States and found that the small difference between static and dynamic models suggests that lagged responses to price or income changes are relatively short.
Abstract: systematically affect price and income elasticity estimates in studies of gasoline demand in the United States . Elasticity estimates from previous studies are used as the dependent variable with data characteristics, model structure , and estimation technique as the independent variables. Included among the explanatory variables are functional form, lag structure, time span, and national setting (U.S. versus the U.S. pooled with other countries). Inclusion of vehicle ownership in gasoline demand studies is found to result in lower estimates of income elasticity, data sets which pool U.S. and foreign data result in larger (absolute) estimates of both price and income elasticity, and the small difference between static and dynamic models suggests that lagged responses to price or income changes are relatively short. This study also found that elasticity estimates appear relatively robust across estimation techniques.
TL;DR: In this article, the authors review imaging techniques for assessing the elastic properties of tissue and briefly look at the fundamental techniques in the above-mentioned fields and then present elastography techniques developed by current research groups.
Abstract: In this article the authors review imaging techniques for assessing the elastic properties of tissue. They briefly look at the fundamental techniques in the above-mentioned fields and then present elastography techniques developed by current research groups. The authors' review is focused on published papers in the archival literature.
TL;DR: In this article, a compendium of pressure-volume-temperature data of polymers is presented, where each sample is fully identified as to origin and molecular weight, molecular weight distribution and treatment immediately before the test.
Abstract: bons, hydrocarbon polymers, ethylene copolymers, styrenics, acrylics, polyacrylonitrile and copolymers, other C-C main chain polymers, polyethers, polyamides, polyesters, main chain aromatics, and polymer blends. Data for approximately 200 polymers are presented. Each sample is fully identified as to origin, molecular weight, molecular weight distribution and treatment immediately before the test. Specific volume under ambient conditions is also given for each polymer. This book is a careful and complete compendium of pressure-volume-temperature data of polymers.
TL;DR: In this article, a class of integral equation methods for the solution of biharmonic boundary value problems, with applications to two-dimensional Stokes flow and isotropic elasticity, is presented.
TL;DR: In this paper, it was shown that knowledge of scale efficiency does not permit the calculation of scale elasticity or vice versa, and a direct approach to determine the scale properties was proposed to calculate the scale elasticities from the dual problem to calculate of Farrell efficiency measures.
Abstract: An issue in the multiple-output case within the literature on piecewise linear frontier production functions has been how to determine the nature of the scale properties. It is shown that knowledge of scale efficiency does not permit calculation of scale elasticity or vice versa. For inefficient units there is a relationship between input-saving and output-increasing efficiency measures through the average value of the scale elasticity between the two different reference points on the frontier. A direct approach to determine the scale properties is to calculate the scale elasticity from the dual problem to the calculation of Farrell efficiency measures.
TL;DR: Experimental evidence of the striking influence of small additions of high molecular weight polymers on stability and pattern selection in Couette-Taylor flow is presented.
Abstract: We present experimental evidence of the striking influence of small additions of high molecular weight polymers on stability and pattern selection in Couette-Taylor flow. Two novel oscillatory flow patterns were observed. One of them is essentially due to the fluid elasticity. The other results from inertial instability modified by the elasticity.
TL;DR: In this article, the authors studied the linear and non-linear elastic behavior, the breaking stress and breaking strain of gelatin gels as a function of a number of experimental conditions: gelatin concentration, gelatin bloom value, ageing time, ageing temperature, pH, NaCl and CaCl2 concentration, whey protein concentration, the amount of pre-shearing, strain rate or compression speed, using both shear deformation and compression.
TL;DR: In this article, a thermodynamic model for phase separation induced by the increase of network elasticity during free-radical cross-linking polymerization is presented in conversion−phase diagrams.
Abstract: A thermodynamic model is given for phase separation induced by the increase of network elasticity during free-radical cross-linking polymerization. The importance of network elasticity in the field of polymer dispersed liquid crystals is stressed. The concept of a conversion−phase diagram is introduced as an attractive way to visualize the onset of phase separation in all situations where the phase separation is induced by polymerization. The results of the model are presented in conversion−phase diagrams.
TL;DR: In this paper, the authors developed hypotheses on the relationship between regular price elasticity and retailer promotional variables, and between price sensitivity and retailer pricing policy, and tested these hypotheses by analyzing the variation of a frequently purchased consumer packaged brand across stores, both within and across chains.
TL;DR: Analysis of velocity, elasticity and density data for a range of reference materials demonstrated that experimentally measured longitudinal wave velocity could be reliably substituted into the bar wave equation (v = square root E/p), implying that a combination of velocity and apparent density may be an improved indicator of bone fragility than density alone.
TL;DR: In this article, a review of recent advances in modeling of elastic composites and polycrystals by spring networks is presented, and applications to progressive breakdown in elastic-brittle matrix-inclusion composites, and aluminum sheets are discussed.
TL;DR: In this article, the authors measured disjoining pressure isotherms for foam films made from octyl β-glucoside, measured at different surfactant concentrations, ionic strengths, and solution pH values.
Abstract: Disjoining pressure isotherms for foam films made from a nonionic surfactant, octyl β-glucoside, are measured at different surfactant concentrations, ionic strengths, and solution pH values. Below the cmc an electrostatic double-layer repulsion is present and dominates the long-range interaction. The decay length of the forces agrees with the expected Debye length and the measured long-range interactions are consistent with solutions to the nonlinear Poisson−Boltzmann equation using constant charge conditions. The deduced surface charge densities increase with pH and ionic strength but decrease with increasing surfactant concentration. At, or just above, the cmc, surfactant covers the interface and suppresses the charge sufficiently to induce a transition from a common black film to a Newton black film. Ultimately, the film stability is determined by both surface forces and elasticity. Combining both, via an overall film tension, leads to a general expression for the film elasticity.
TL;DR: In this paper, the authors discussed the prediction of the dispersed phase drop diameter in polymer blends considering the viscoelastic properties of polymers, and the prediction is based on a simple force proportionality.
Abstract: This paper discusses the prediction of the dispersed phase drop diameter in polymer blends considering the viscoelastic properties of polymers. The prediction is based on a simple force proportionality. Polymers are viscoelastic, and thus the elasticity of the matrix and the elasticity of the dispersed phase affect the drop size. The forces that deform a polymer droplet in a polymer matrix are the shear forces, η m γ and the matrix first normal stress, T 11,m . This deformation is resisted by the interfacial forces, 2 Γ/D and the drop's first normal stress, T 11,d . As a first approximation, the forces were balanced to predict the particle size in polymer blends. The diameter of the dispersed phase was predicted reasonably well for several systems at different operating conditions. It was observed for some systems (PS/PP, PS/EPMA, PS/PA330) that, as the shear rate increased, the diameter of the dispersed phase initially decreased. At a critical shear rate, the diameter reached a minimum value, and beyond it, the diameter increased with shear. This critical value was found to be between 100 to 162.5 s -1 for a PS/PP system. The force balance predicts this minimum drop diameter at a similar critical shear rate. The specific energy input (the amount of energy input into the blend) could not explain the phenomenon of a minimum drop diameter with increase in shear. This minimum is not observed for the high concentration systems, such as the 20% PP dispersed in PS, since the effects of coalescence become significant. In reactive blends, the predicted drop diameter was closer to the experimentally determined diameter, and there was less variation in diameter with changes in shear rate.
TL;DR: In this paper, the effects of applying high loads to a powder bed on the properties of compacts of sodium chloride, sucrose and polyethylene glycol were studied, and the porosity (apparent zero) and tensile strength levelled off when a high enough load was applied.
TL;DR: In this article, the authors studied resonances associated to the elasticity operator in the exterior of an arbitrary obstacle in R3 with Neumann boundary conditions and proved that there exists a sequence of resonances tending rapidly to the real axis.
Abstract: We study resonances (scattering poles) associated to the elasticity operator in the exterior of an arbitrary obstacle inR3 with Neumann boundary conditions. We prove that there exists a sequence of resonances tending rapidly to the real axis.
TL;DR: The theory of elasticity in two-dimensional systems is discussed and applied to several specific cases of interest in this paper, in particular the elastic behavior of solid Langmuir−Blodgett films.
Abstract: The theory of elasticity in two-dimensional systems is discussed and applied to several specific cases of interest. In particular the elastic behavior of solid Langmuir−Blodgett films is reviewed a...
IBM1
TL;DR: In this paper, the authors used an interatomic potential recently developed by J. P. Sethna to find that brittle cracks approach six-tenths the Rayleigh speed and follow the highest surface energy path.
Abstract: Simulations show that brittle cracks approach six-tenths the Rayleigh speed and follow the highest surface energy path. Using an interatomic potential recently developed by J. P. Sethna, we find that the crack's limiting speed now approaches the theoretical prediction of the Rayleigh speed, but the crack path is still associated with greatest elastic stiffness and surface energy. We conclude that the crack's dynamics is governed by the anisotropic mean-field elasticity associated with large strains ( $\ensuremath{\ge}7%$).
TL;DR: In this article, the standard neoclassical growth model is modified by introducing a market structure characterized by monopolistic competition and variable demand elasticities, and the price elasticity of the demand schedule facing a typical firm is a function of the aggregate savings rate.
Abstract: The standard neoclassical growth model is modified by introducing a market structure characterized by monopolistic competition and variable demand elasticities. In equilibrium, the price elasticity of the demand schedule facing a typical firm is a function of the aggregate savings rate. The latter feature results from an assumed wedge between the elasticity of substitution across goods in productive activities and that in consumption. In contrast with most examples in the literature our model does not require increasing returns (internal or external) in order to generate multiple equilibria.