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Showing papers on "Elasticity (economics) published in 2014"


Journal ArticleDOI
TL;DR: In this article, the authors present necessary and sufficient conditions for elastic stability in all crystal classes, as a concise and pedagogical reference to stability criteria in noncubic materials.
Abstract: While the Born elastic stability criteria are well known for cubic crystals, there is some confusion in the literature about the form they should take for lower-symmetry crystal classes Here we present closed form necessary and sufficient conditions for elastic stability in all crystal classes, as a concise and pedagogical reference to stability criteria in noncubic materials

2,199 citations


Book
01 Jan 2014
TL;DR: This book by a renowned structural engineer offers comprehensive coverage of both static and dynamic analysis of plate behavior, including classical, numerical, and engineering solutions.
Abstract: This book by a renowned structural engineer offers comprehensive coverage of both static and dynamic analysis of plate behavior, including classical, numerical, and engineering solutions. It contains more than 100 worked examples showing step by step how the various types of analysis are performed.

294 citations


Journal ArticleDOI
TL;DR: The feasibility of using supersonic shear wave elastography to quantify passive stretching characteristics of individual muscle is demonstrated and preliminary normative values of slack angle, slack elasticity, and rate of increase in elasticity for human tibialis anterior muscles are provided.

132 citations


Journal ArticleDOI
TL;DR: In this paper, the effect of protein type, concentration, pH and temperature has been studied using droplet size distribution, interfacial tension, and interfacial elasticity measurements using the pendant drop method.

120 citations


Journal ArticleDOI
TL;DR: In this paper, the effects of blockage ratio (d/D), flow rate (Q), and entry length (L) on particle migration induced by fluid elasticity were evaluated.
Abstract: The elasto-migration of microparticles across a streamline induced by elasticity and inertia in microscale pipe flow of viscoelastic fluids was investigated using a holographic technique. The effects of blockage ratio (d/D), flow rate (Q), and entry length (L) on particle migration induced by fluid elasticity were evaluated. Single-line particle focusing was demonstrated for an elasticity-dominant fluid. Furthermore, shear-thinning effect on particle migration was evaluated. Finally, we propose the focusing number, a non-dimensional parameter, to estimate the focusing state of particles in elasticity-dominant fluids. This criterion can be used to accurately estimate the design parameters, such as rheological properties, channel length, and particle diameter, for microfluidic devices using elasto-migration.

109 citations


Posted Content
TL;DR: In this paper, a multiscale elasticity, molecular dynamics, and density functional theory model is applied to the interpretation of X-ray micro-diffraction and surface acoustic wave spectroscopy, measuring lattice swelling and elastic modulus changes in a W-1%Re alloy after implantation with 3110 appm of helium.
Abstract: Using X-ray micro-diffraction and surface acoustic wave spectroscopy, we measure lattice swelling and elastic modulus changes in a W-1%Re alloy after implantation with 3110 appm of helium. A fraction of a percent observed lattice expansion gives rise to an order of magnitude larger reduction in the surface acoustic wave velocity. A multiscale elasticity, molecular dynamics, and density functional theory model is applied to the interpretation of observations. The measured lattice swelling is consistent with the relaxation volume of self-interstitial and helium-filled vacancy defects that dominate the helium-implanted material microstructure. Molecular dynamics simulations confirm the elasticity model for swelling. Elastic properties of the implanted surface layer also change due to defects. The reduction of surface acoustic wave velocity predicted by density functional theory calculations agrees remarkably well with experimental observations.

98 citations


Journal ArticleDOI
TL;DR: In this article, the authors consider the non-singular theory of discrete dislocation loops in gradient elasticity of Helmholtz type, with interest in its applications to three dimensional dislocation dynamics (DD) simulations.
Abstract: The singular nature of the elastic fields produced by dislocations presents conceptual challenges and computational difficulties in the implementation of discrete dislocation-based models of plasticity. In the context of classical elasticity, attempts to regularize the elastic fields of discrete dislocations encounter intrinsic difficulties. On the other hand, in gradient elasticity, the issue of singularity can be removed at the outset and smooth elastic fields of dislocations are available. In this work we consider theoretical and numerical aspects of the non-singular theory of discrete dislocation loops in gradient elasticity of Helmholtz type, with interest in its applications to three dimensional dislocation dynamics (DD) simulations. The gradient solution is developed and compared to its singular and non-singular counterparts in classical elasticity using the unified framework of eigenstrain theory. The fundamental equations of curved dislocation theory are given as non-singular line integrals suitable for numerical implementation using fast one-dimensional quadrature. These include expressions for the interaction energy between two dislocation loops and the line integral form of the generalized solid angle associated with dislocations having a spread core. The single characteristic length scale of Helmholtz elasticity is determined from independent molecular statics (MS) calculations. The gradient solution is implemented numerically within our variational formulation of DD, with several examples illustrating the viability of the non-singular solution. The displacement field around a dislocation loop is shown to be smooth, and the loop self-energy non-divergent, as expected from atomic configurations of crystalline materials. The loop nucleation energy barrier and its dependence on the applied shear stress are computed and shown to be in good agreement with atomistic calculations. DD simulations of Lomer–Cottrell junctions in Al show that the strength of the junction and its configuration are easily obtained, without ad-hoc regularization of the singular fields. Numerical convergence studies related to the implementation of the non-singular theory in DD are presented.

97 citations


Journal ArticleDOI
TL;DR: The model predicted that matrix elasticity dominates over intracellular elasticity, suggesting that the extracellular matrix may potentially be a more effective therapeutic target than microtubules, and suggest that myocytes with lower aspect ratios have a functional advantage when the elasticity of the extacellular matrix decreases due to conditions such as fibrosis.
Abstract: Concentric hypertrophy is characterized by ventricular wall thickening, fibrosis, and decreased myocyte length-to-width aspect ratio. Ventricular thickening is considered compensatory because it reduces wall stress, but the functional consequences of cell shape remodeling in this pathological setting are unknown. We hypothesized that decreases in myocyte aspect ratio allow myocytes to maximize contractility when the extracellular matrix becomes stiffer due to conditions such as fibrosis. To test this, we engineered neonatal rat ventricular myocytes into rectangles mimicking the 2-D profiles of healthy and hypertrophied myocytes on hydrogels with moderate (13 kPa) and high (90 kPa) elastic moduli. Actin alignment was unaffected by matrix elasticity, but sarcomere content was typically higher on stiff gels. Microtubule polymerization was higher on stiff gels, implying increased intracellular elastic modulus. On moderate gels, myocytes with moderate aspect ratios (∼7:1) generated the most peak systolic work compared with other cell shapes. However, on stiffer gels, low aspect ratios (∼2:1) generated the most peak systolic work. To compare the relative contributions of intracellular vs. extracellular elasticity to contractility, we developed an analytical model and used our experimental data to fit unknown parameters. Our model predicted that matrix elasticity dominates over intracellular elasticity, suggesting that the extracellular matrix may potentially be a more effective therapeutic target than microtubules. Our data and model suggest that myocytes with lower aspect ratios have a functional advantage when the elasticity of the extracellular matrix decreases due to conditions such as fibrosis, highlighting the role of the extracellular matrix in cardiac disease.

95 citations


Journal ArticleDOI
TL;DR: Results from estimating several meta-regressions reveal that these price elasticity estimates are influenced by a number of study characteristics, including whether demand is modeled in the short-run or the long-run, measures of quantity and price, and the location of demand.
Abstract: Because of the increased availability of price data over the past 15 years, several studies have estimated the demand for illicit drugs, providing 462 estimates of the price elasticity. Results from estimating several meta-regressions reveal that these price elasticity estimates are influenced by a number of study characteristics. For instance, the price elasticity differs across drugs, with its absolute value being smallest for marijuana, compared with cocaine and heroin. Furthermore, price elasticity estimates are sensitive to whether demand is modeled in the short-run or the long-run, measures of quantity and price, whether or not alcohol and other illicit drugs are included in the specification of demand, and the location of demand. However, a number of other factors, including the functional form of demand, several specification issues, the type of data and method used to estimate demand, and the quality of the publication outlet, have less influence on the price elasticity.

88 citations


Journal ArticleDOI
TL;DR: SWE may serve as a complementary tool for diagnosis of breast lesions and yield additional valuable quantitative data to ultrasonographic examination on solid breast lesions through correlations between elasticity values of solid breast masses and histopathological findings.
Abstract: Purpose We aimed to determine the correlations between the elasticity values of solid breast masses and histopathological findings to define cutoff elasticity values differentiating malignant from benign lesions. Materials and methods A total of 115 solid breast lesions of 109 consecutive patients were evaluated prospectively using shear wave elastography (SWE). Two orthogonal elastographic images of each lesion were obtained. Minimum, mean, and maximum elasticity values were calculated in regions of interest placed over the stiffest areas on the two images; we also calculated mass/fat elasticity ratios. Correlation of elastographic measurements with histopathological results were studied. Results Eighty-three benign and thirty-two malignant lesions were histopathologically diagnosed. The minimum, mean, and maximum elasticity values, and the mass/fat elasticity ratios of malignant lesions, were significantly higher than those of benign lesions. The cutoff value was 45.7 kPa for mean elasticity (sensitivity, 96%; specificity, 95%), 54.3 kPa for maximum elasticity (sensitivity, 95%; specificity, 94%), 37.1 kPa for minimum elasticity (sensitivity, 96%; specificity, 95%), and 4.6 for the mass/fat elasticity ratio (sensitivity, 97%; specificity, 95%). Conclusion SWE yields additional valuable quantitative data to ultrasonographic examination on solid breast lesions. SWE may serve as a complementary tool for diagnosis of breast lesions. Long-term clinical studies are required to accurately select lesions requiring biopsy.

87 citations


Journal ArticleDOI
TL;DR: There was improvement in the diagnostic performance of ultrasound of mass assessment with shear wave elastography parameters added to BI-RADS category 4a masses compared with ultrasound alone and the AUC of combined ultrasound and elasticity ratio was the highest compared with the other combined parameters.
Abstract: OBJECTIVE. The purpose of this article is to assess the diagnostic performance of quantitative shear wave elastography in the evaluation of solid breast masses and to determine the most discriminatory parameter. SUBJECTS AND METHODS. B-mode ultrasound and shear wave elastography were performed before core biopsy of 123 masses in 112 women. The diagnostic performance of ultrasound and quantitative shear wave elastography parameters (mean elasticity, maximum elasticity, and elasticity ratio) were compared. The added effect of shear wave elastography on the performance of ultrasound was determined. RESULTS. The mean elasticity, maximum elasticity, and elasticity ratio were 24.8 kPa, 30.3 kPa, and 1.90, respectively, for 79 benign masses and 130.7 kPa, 154.9 kPa, and 11.52, respectively, for 44 malignant masses (p < 0.001). The optimal cutoff value for each parameter was determined to be 42.5 kPa, 46.7 kPa, and 3.56, respectively. The AUC of each shear wave elastography parameter was higher than that of ultra...

Journal ArticleDOI
TL;DR: In this article, the lateral migration of microspheres across streamlines induced by elasticity and inertia in a square microchannel flow of viscoelastic fluids is investigated using a holographic microscopy technique.
Abstract: The lateral migration of microspheres across streamlines induced by elasticity and inertia in a square microchannel flow of viscoelastic fluids is investigated using a holographic microscopy technique. We experimentally demonstrate the exact particle positions driven by the elasticity of fluid in the channel cross-section. The effects of the blockage ratio, flow rate, and shear-thinning property of the viscoelastic fluids on particle migration are evaluated. In particular, the focusing patterns of microspheres in three-dimensional volume are analyzed under different conditions, namely, dominant inertia, dominant elasticity, and the combined effects of inertia and elasticity.

Journal ArticleDOI
TL;DR: It is found that cell spreading and focal adhesion characteristics are dependent on elasticity for all types of coatings, albeit with significant differences in magnitude, and indicates that cell adhesion, polarity, and associated migration persistence are tuned by substrate elasticity and biochemical properties.

Journal ArticleDOI
TL;DR: In this paper, the first complete three-dimensional numerical solutions to a broad range of boundary value problems for a general theory of finite strain gradient elasticity were presented, to the best of our knowledge.

Posted Content
TL;DR: A linear stability analysis confirmed that this long wavelength instability is due to an elastocapillary effect and suggests some new results related to the role of the finite dilation of a material in interfacial pattern formation that may have nontrivial consequences in the adhesive delamination of very thin and/or soft elastic films via self-generated cracks.
Abstract: An adhesively stressed thin film of a soft hydrogel confined between two rigid flat substrates auto-roughens with its dominant wavelength exhibiting pronounced dependence on the film thickness (H). A linear stability analysis confirmed that this long wavelength instability (~7H) is due to an elasto-capillary effect, the implementation of which required direct measurements of the surface tension and the elasticity of the gel. The surface tension of the gel was estimated from the fundamental spherical harmonic of a hemispherical cap of the gel that was excited by an external noise. The shear modulus of the gel was determined from its resonant shear mode in a confined geometry. During the course of this study, it was found that a high density steel ball submerges itself inside the gel by balancing its excess weight with the accumulated strain induced elastic force that allows another estimation of its elastic modulus. The large ratio (1.8 mm) of the surface tension to its elasticity ascertains the role of elasto-capillarity in the adhesion induced pattern formation with such gels. Experimental results are in accord with a linear stability analysis that predicts that the rescaled wavelength is linear with H, which modifies the conventional stress to pull-off a rigid flat object from a very soft film by a multiplicative factor. The analysis also suggests some new results related to the role of the finite dilation of a material in interfacial pattern formation that may have non-trivial consequences in the adhesive delamination of very thin and/or soft elastic films via self-generated cracks.

Journal ArticleDOI
TL;DR: Hematic elasticity values measured with SWE in histologically proven normal livers ranged from 2.6 to 6.2 kPa, with high measurement reliability, and the effect of the potential confounding factors on liver elasticity was negligible.
Abstract: Hepatic elasticity values of histologically proven normal livers measured with shear-wave elastography ranged from 2.6 to 6.2 kPa (by using lower and upper limits at the 2.5 and 97.5 percentiles) and were highly reliable.

Posted Content
TL;DR: This article studied the implications of microeconomic heterogeneity for aggregate technology, showing that the aggregate elasticity of substitution between capital and labor can be expressed as a simple function of plant level structural parameters and sufficient statistics for plant heterogeneity.
Abstract: We study the implications of microeconomic heterogeneity for aggregate technology, showing that the aggregate elasticity of substitution between capital and labor can be expressed as a simple function of plant level structural parameters and sufficient statistics for plant heterogeneity. This allows for a new approach to estimating the aggregate elasticity using microeconomic data and allows us to examine how the aggregate elasticity varies over time or across countries. We then use plant level data from the Census of Manufactures to construct an aggregate elasticity of substitution for the manufacturing sector, and estimate an aggregate elasticity of approximately 0.72 in 1987. We find that the aggregate elasticity has risen over time in the US and is higher in less developed countries. These differences are quantitatively important; our estimates imply that a change in the interest rate has a 50 percent larger impact on India than the US. Finally, we measure the bias of aggregate technical change using our estimates of the aggregate elasticity, and find that the bias of technical change has increased in recent years.

Book
24 Jun 2014
TL;DR: In this article, a detailed treatment of computer methods with numerical examples are provided, including variational and Galerkin formulations of the heat conduction, beams and elasticity problems.
Abstract: This book covers all basic areas of mechanical engineering, such as fluid mechanics, heat conduction, beams and elasticity with detailed derivations for the mass, stiffness and force matrices. It is especially designed to give physical feeling to the reader for finite element approximation by the introduction of finite elements to the elevation of elastic membrane. A detailed treatment of computer methods with numerical examples are provided. In the fluid mechanics chapter, the conventional and vorticity transport formulations for viscous incompressible fluid flow with discussion on the method of solution are presented. The variational and Galerkin formulations of the heat conduction, beams and elasticity problems are also discussed in detail. Three computer codes are provided to solve the elastic membrane problem. One of them solves the Poissons equation. The second computer program handles the two dimensional elasticity problems and the third one presents the three dimensional transient heat conduction problems. The programs are written in C++ environment.

Journal ArticleDOI
TL;DR: In this article, the generalized continuum theory of couple-stress elasticity is used to analyze the structural properties of a deformable elastic half-plane by a flat punch, then by a cylindrical indentor and finally by a shallow wedge indentor.

Journal ArticleDOI
TL;DR: In this paper, a finite strain theory for anisotropic single crystals undergoing shock loading is developed for the thermo-elastic regime, at axial stresses up to the Hugoniot elastic limit.

Posted Content
TL;DR: In this article, the authors investigate the Armington elasticity of substitution between goods from different countries, and explore estimation techniques for the macro and micro elasticities using both simulated data from a Melitz-style model, and highly disaggregate U.S. production data matched to Harmonized System trade data.
Abstract: The elasticity of substitution between goods from different countries—the Armington elasticity—is important for many questions in international economics, but its magnitude is subject to debate: the "macro" elasticity between home and import goods is often found to be smaller than the "micro" elasticity between foreign sources of imports. We investigate these two elasticities in a model using a nested CES preference structure. We explore estimation techniques for the macro and micro elasticities using both simulated data from a Melitz-style model, and highly disaggregate U.S. production data matched to Harmonized System trade data. We find that in up to one-half of goods there is no significant difference between the macro and micro elasticities, but in the other half of goods the macro elasticity is significantly lower than the micro elasticity, even when they are estimated at the same level of disaggregation.

Journal ArticleDOI
TL;DR: The relevant aspects of cell elasticity that contribute to the rheological response of blood at high confinement are identified and controlled by the geometry of the channel.
Abstract: We analyze the rheology of dilute red blood cell suspensions in pressure driven flows at low Reynolds number, in terms of the morphologies and elasticity of the cells. We focus on narrow channels of width similar to the cell diameter, when the interactions with the walls dominate the cell dynamics. The suspension presents a shear-thinning behaviour, with a Newtonian-behaviour at low shear rates, an intermediate region of strong decay of the suspension viscosity, and an asymptotic regime at high shear rates in which the effective viscosity converges to that of the solvent. We identify the relevant aspects of cell elasticity that contribute to the rheological response of blood at high confinement. In a second paper, we will explore the focusing of red blood cells while flowing at high shear rates and how this effect is controlled by the geometry of the channel.

Journal ArticleDOI
TL;DR: In this paper, the authors used a cantilevered beam bending technique to measure the Young modulus and yield strength of silver nanowires (Ag NWs) inside a scanning electron microscope with diameters ranging from 76 nm to 211 nm.

Journal ArticleDOI
TL;DR: This paper examined the disparity in estimates of the income elasticity of air travel across the literature by applying meta-regression techniques and found that while the authors' preferred baseline of 1.186 is consistent with air travel being a luxury and a slightly immature market, there are several features of the literature which sway the expected income elasticities away from this baseline.

Journal ArticleDOI
TL;DR: In this paper, the authors proposed an alternative approach to the identification problem of the symmetry class, based on polynomial invariants and covariants of the elasticity tensor C, rather than on spectral properties of the Kelvin representation.
Abstract: In this paper, we explore new conditions for an elasticity tensor to belong to a given symmetry class. Our goal is to propose an alternative approach to the identification problem of the symmetry class, based on polynomial invariants and covariants of the elasticity tensor C, rather than on spectral properties of the Kelvin representation. We compute a set of algebraic relations which describe precisely the orthotropic ([D2]), trigonal ([D3]), tetragonal ([D4]), transverse isotropic ([SO(2)]) and cubic ([O]) symmetry classes in H4, the higher irreducible component in the decomposition of Ela. We provide a bifurcation diagram which describes how one "travel" in H4 from a given isotropy class to another. Finally, we study the link between these polynomial invariants and those obtained as the coefficients of the characteristic or the Betten polynomials.We show, in particular, that the Betten invariants do not separate the orbits of the elasticity tensors.

Journal ArticleDOI
TL;DR: In this article, the elastic properties of soft solids containing air bubbles are studied and the authors demonstrate how the elastic response of the soft porous solid is governed by two dimensionless parameters: the gas volume fraction and a capillary number comparing the elasticity of the matrix with the stiffness of the bubbles.
Abstract: We study the elastic properties of soft solids containing air bubbles. Contrary to standard porous materials, the softness of the matrix allows for a coupling of the matrix elasticity to surface tension forces acting on the bubble surface. Thanks to appropriate experiments on model systems, we demonstrate how the elastic response of the soft porous solid is governed by two dimensionless parameters: the gas volume fraction and a capillary number comparing the elasticity of the matrix with the stiffness of the bubbles. Furthermore, we show that our experimental results are accurately predicted by computations of the shear modulus through a micro-mechanical approach.

Journal ArticleDOI
TL;DR: In this article, a lattice model with long-range interaction of power-law type that is connected with difference of non-integer order is suggested, where the continuous limit maps the equations of motion of lattice particles into continuum equations with fractional Grunwald-Letnikov-Riesz derivatives.

Journal ArticleDOI
TL;DR: In this paper, an elasticity solution for the functionally graded thick-walled tube subjected to internal pressure is given in terms of volume fractions of constituents, where the tube consists of two linear elastic constituents and the volume fraction for one phase is a power function c ( r ) = c 0 [ 1 − k ( r / b ) n ] varied in the radial direction.

Journal ArticleDOI
01 Dec 2014-EPL
TL;DR: In this paper, the shape of an avalanche at a fixed size and a fixed duration was calculated for both short-range and long-range elasticity, where the exponent is given by the two independent exponents at depinning, the roughness ζ and the dynamical exponent z. The exact expression, though different from the phenomenological form presented by Laurson et al. in Nat. Commun., 4 (2013) 2927, is well approximated by, 0.
Abstract: Elastic systems, such as magnetic domain walls, density waves, contact lines, and cracks, are pinned by substrate disorder. When driven, they move via avalanches, with power law distributions of size, duration and velocity. Their exponents, and the shape of an avalanche, defined as its mean velocity as a function of time, were studied. They are known approximatively from experiments and simulations, and were predicted from mean-field models, such as the Brownian force model (BFM), where each point of the elastic interface sees a force field which itself is a random walk. As we showed in EPL, 97 (2012) 46004, the BFM is the starting point for an expansion around the upper critical dimension, with for short-ranged elasticity, and for long-ranged elasticity. Here we calculate analytically the , i.e. 1-loop, correction to the avalanche shape at fixed duration T, for both types of elasticity. The exact expression, though different from the phenomenological form presented by Laurson et al. in Nat. Commun., 4 (2013) 2927, is well approximated by , 0 < x < 1. The asymmetry is negative for d close to , skewing the avalanche towards its end, as observed in numerical simulations in d = 2 and 3. The exponent is given by the two independent exponents at depinning, the roughness ζ and the dynamical exponent z. We propose a general procedure to predict other avalanche exponents in terms of ζ and z. We finally introduce and calculate the shape at fixed avalanche size, not yet measured in experiments or simulations.

Journal ArticleDOI
TL;DR: In this paper, a coupled linear dynamical theory of elasticity for solids with double porosity is proposed and basic internal and external boundary value problems of steady vibrations are formulated, and finally, uniqueness theorems for regular (classical) solutions of these BVPs are proved.
Abstract: This paper concerns with the coupled linear dynamical theory of elasticity for solids with double porosity. Basic properties of plane harmonic waves are established. Radiation conditions of regular vectors are given. Basic internal and external boundary value problems (BVPs) of steady vibrations are formulated, and finally, uniqueness theorems for regular (classical) solutions of these BVPs are proved.