The Experts below are selected from a list of 45 Experts worldwide ranked by ideXlab platform
A. M. Glazer - One of the best experts on this subject based on the ideXlab platform.
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Diffuse X-ray scattering in potassium lithium sulfate, KLiSO4
Journal of Applied Crystallography, 1994Co-Authors: Thomas Welberry, A. M. GlazerAbstract:Detailed diffuse X-ray scattering patterns of potassium lithium sulfate, KLiSOn, in sections normal to [00.1], have been recorded using a position-sensitive detector system. A number of distinctive diffuse features are observed including elongated diffuse peaks near Braggpeak positions, bands of weaker intensity running normal to a*, b* etc. and darker regions relatively free from scattering in the shape of hexagons and a six-pointed star. Monte Carlo simulation of simple potential models has been carried out in an attempt to explain this scattering and also the observation from Bragg analysis [Schulz, Zucker & Frech (1985). Acta Crvst. Bnl, 21-26] that mean-square atomic displacements for the apical O(1) atom show a pronounced threefold symmetry. A simple potential, in which harmonic (Hookes Law) springs with lengths equal to the observed average bond distances are assumed between the different types of nearestneighbour atom pairs, is able to account qualitatively for all of the observed diffraction features but gives quite isotropic atomic displacement distributions. A second model is described, which assumes that a small number of point defects are present, in which the potassium sites are occasionally occupied by lithium. The distortion of the very flexible LiOn framework around such defects can account for the trigonal shape of the O( 1 ) sites while still giving diffuse diffraction patterns similar to those from the simpler harmonic model.
Maciej Matyka - One of the best experts on this subject based on the ideXlab platform.
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The Pressure Soft Body a Simple Model of Complex Behavior
2015Co-Authors: Maciej MatykaAbstract:SIMPLE computational model of soft body animation in two and three dimensions is introduced. The model is based on fundamental principles: Newton’s Laws, Hookes Law and Ideal GasLaw. The simulated body consists of material points connected by springs. Additionally, pressure force on the body surface is applied. An equation of motion for each point is solved. The advantages of the model for educational applications are: it is based on fundamental physics Laws; it is very fast and allows for an interactive simulation on home PC; its concept is simple enough to be understood by students. The model may be used as a representative example of physically based modelling in computer graphics and animation. Figure 1: The pressurized soft ball falling on the ground. The red lines indicate local velocity vectors of mass points building the shape of the object. 2. Spring-Mass model WE start from spring-mass model [1] that has beenwidely used in computer graphics and animation-mostly due to the simplicity and flexibility of its original form. Figure 2: The spring-mass model of cloth dynamics The spring-mass model contains mass particles connected by linear springs in both off- and diagonal directions (see figure 2). The Newton’s Laws of motion give ordinary differ-ential equations describing dynamics of the model: d2~ri dt2 = ~Fi/mi, where mi is the i-th point mass, ~ri is it position and ~Fi
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The Pressure Soft Body a Simple Model of Complex Behavior
2007Co-Authors: Maciej MatykaAbstract:IMPLE computational model of soft body animation in two and three dimensions is introduced. The model is based on fundamental principles: Newton’s Laws, Hookes Law and Ideal Gas Law. The simulated body consists of material points connected by springs. Additionally, pressure force on the body surface is applied. An equation of motion for each point is solved. The advantages of the model for educational applications are: it is based on fundamental physics Laws; it is very fast and allows for an interactive simulation on home PC; its concept is simple enough to be understood by students. The model may be used as arepresentative example of physically based modelling in computer graphics and animation.
Thomas Welberry - One of the best experts on this subject based on the ideXlab platform.
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Diffuse X-ray scattering in potassium lithium sulfate, KLiSO4
Journal of Applied Crystallography, 1994Co-Authors: Thomas Welberry, A. M. GlazerAbstract:Detailed diffuse X-ray scattering patterns of potassium lithium sulfate, KLiSOn, in sections normal to [00.1], have been recorded using a position-sensitive detector system. A number of distinctive diffuse features are observed including elongated diffuse peaks near Braggpeak positions, bands of weaker intensity running normal to a*, b* etc. and darker regions relatively free from scattering in the shape of hexagons and a six-pointed star. Monte Carlo simulation of simple potential models has been carried out in an attempt to explain this scattering and also the observation from Bragg analysis [Schulz, Zucker & Frech (1985). Acta Crvst. Bnl, 21-26] that mean-square atomic displacements for the apical O(1) atom show a pronounced threefold symmetry. A simple potential, in which harmonic (Hookes Law) springs with lengths equal to the observed average bond distances are assumed between the different types of nearestneighbour atom pairs, is able to account qualitatively for all of the observed diffraction features but gives quite isotropic atomic displacement distributions. A second model is described, which assumes that a small number of point defects are present, in which the potassium sites are occasionally occupied by lithium. The distortion of the very flexible LiOn framework around such defects can account for the trigonal shape of the O( 1 ) sites while still giving diffuse diffraction patterns similar to those from the simpler harmonic model.
K. Kannan - One of the best experts on this subject based on the ideXlab platform.
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Smoothed polygonal finite element method for generalized elastic solids subjected to torsion
Computers & Structures, 2017Co-Authors: M. Sellam, Sundararajan Natarajan, K. KannanAbstract:Explicit thermodynamically consistent constitutive equations are employed.Domain is discretized with serendipity polygonal elements.Lagrange type higher order shape functions are constructed based on pairwise products of barycentric coordinates.A new one point integration scheme is proposed to compute the smoothed (corrected) derivatives.The numerical results with new constitutive equations show stress softening behavior even in small strain regime. Orthopaedic implants made of titanium alloy such as Ti-30Nb-10Ta-5Zr (TNTZ-30) are biocompatible and exhibit nonlinear elastic behavior in the small strain regime (Hao et al., 2005). Conventional material modeling approach based on Cauchy or Green elasticity, upon linearization of the strain, inexorably leads to Hookes Law which is incapable of describing the said nonlinear response. Recently, Rajagopal introduced a generalization of the theory of elastic materials (Rajagopal, 2003, 2014), wherein the linearized strain can be expressed as a nonlinear function of stress. Consequently, Devendiran et al. (2016) developed a thermodynamically consistent constitutive equation for the generalized elastic solid, in order to capture the response of materials showing nonlinear behavior in the small strain regime. In this paper, we study the response of a long cylinder made of TNTZ-30 with non-circular cross section subjected to end torsion. An explicit form of the constitutive equation derived in Devendiran et al. (2016) is used to study the response of the cylinder. The cross-section is discretized with quadratic serendipity polygonal elements. A novel one point integration rule is presented to compute the corrected derivatives, which are then used to compute the terms in the stiffness matrix. Unlike the conventional Hookes Law, the results computed using the new constitutive equation show stress softening behavior even in the small strain regime.
M. Sellam - One of the best experts on this subject based on the ideXlab platform.
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Smoothed polygonal finite element method for generalized elastic solids subjected to torsion
Computers & Structures, 2017Co-Authors: M. Sellam, Sundararajan Natarajan, K. KannanAbstract:Explicit thermodynamically consistent constitutive equations are employed.Domain is discretized with serendipity polygonal elements.Lagrange type higher order shape functions are constructed based on pairwise products of barycentric coordinates.A new one point integration scheme is proposed to compute the smoothed (corrected) derivatives.The numerical results with new constitutive equations show stress softening behavior even in small strain regime. Orthopaedic implants made of titanium alloy such as Ti-30Nb-10Ta-5Zr (TNTZ-30) are biocompatible and exhibit nonlinear elastic behavior in the small strain regime (Hao et al., 2005). Conventional material modeling approach based on Cauchy or Green elasticity, upon linearization of the strain, inexorably leads to Hookes Law which is incapable of describing the said nonlinear response. Recently, Rajagopal introduced a generalization of the theory of elastic materials (Rajagopal, 2003, 2014), wherein the linearized strain can be expressed as a nonlinear function of stress. Consequently, Devendiran et al. (2016) developed a thermodynamically consistent constitutive equation for the generalized elastic solid, in order to capture the response of materials showing nonlinear behavior in the small strain regime. In this paper, we study the response of a long cylinder made of TNTZ-30 with non-circular cross section subjected to end torsion. An explicit form of the constitutive equation derived in Devendiran et al. (2016) is used to study the response of the cylinder. The cross-section is discretized with quadratic serendipity polygonal elements. A novel one point integration rule is presented to compute the corrected derivatives, which are then used to compute the terms in the stiffness matrix. Unlike the conventional Hookes Law, the results computed using the new constitutive equation show stress softening behavior even in the small strain regime.