... to treat blood clots ( embolism and thromboembolism ). It prolongs PTT. When heparin is administered for therapeutic purposes, ... lupus anticoagulant may be present but may not prolong the PTT result. If the lupus anticoagulant (LA) ...
Constitutive equations for solid propellants
Oezuepek, S.; Becker, E.B.
1997-04-01
Mechanical behavior of the Space Shuttle redesigned solid rocket motor (RSRM) propellant is studied from a phenomenological point of view. Motivated by the study of the experimental data three initially isotropic constitutive models have been developed. All models represent the effect of strain rate, superimposed hydrostatic pressure, and cyclic loading on the stress and dilatation response of the material. A particular emphasis is given to the prediction of volume dilatation. The model resulting in the best representation of the available data is calibrated using only a few tests. The predictions of the model are compared with experiments for several loading conditions not used in the calibration.
Unified constitutive equations of foam materials
Chang, Fu S.; Song, Y.; Lu, D.X.; DeSilva, C.N.
1998-07-01
Foam materials, because of their energy absorbing and recovery behavior during impact as well as lightweight and moldable characteristics, have found more and more applications in the automotive industry. A unified constitutive equation with the effect of compression strain rate, tension strain, and shear strain for foam materials with very low Poisson`s ratio has been developed. The mathematical derivation of the constitutive equation is described in detail. The effect of each parameter in the constitutive equation is studied. Numerical formula and procedure are also included in the paper. The test data of two types of energy absorbing foam materials are used for correlation study: polyurethane foam, which was tested at five compressive strain rates, and polypropylene foam, which was tested for quasi-static compression, tension, and shear. Good correlations have been concluded for both cases.
Thermoelastic constitutive equations for chemically hardening materials
NASA Technical Reports Server (NTRS)
Shaffer, B. W.; Levitsky, M.
1974-01-01
Thermoelastic constitutive equations are derived for a material undergoing solidification or hardening as the result of a chemical reaction. The derivation is based upon a two component model whose composition is determined by the degree of hardening, and makes use of strain-energy considerations. Constitutive equations take the form of stress rate-strain rate relations, in which the coefficients are time-dependent functions of the composition. Specific results are developed for the case of a material of constant bulk modulus which undergoes a transition from an initial liquidlike state into an isotropic elastic solid. Potential applications are discussed.
The constitutive equation for membrane tether extraction.
Chen, Yong; Yao, Da-Kang; Shao, Jin-Yu
2010-12-01
Membrane tethers or nanotubes play a critical role in a variety of cellular and subcellular processes such as leukocyte rolling and intercellular mass transport. The current constitutive equations that describe the relationship between the pulling force and the tether velocity during tether extraction have serious limitations. In this article, we propose a new phenomenological constitutive equation that captures all known characteristics of nanotube formation, including nonlinearity, nonzero threshold force, and possible negative tether velocity. We used tether extraction from endothelial cells as a prototype to illustrate how to obtain the material constants in the constitutive equation. With the micropipette aspiration technique, we measured tether pulling forces at both positive and negative tether velocities. We also determined the threshold force of 55 pN experimentally for the first time. This new constitutive equation unites two established ones and provides us a unified platform to better understand not only the physiological role of tether extraction during leukocyte rolling and intercellular or intracellular transport, but also the physics of membrane tether growth or retraction.
Constitutive equations of ageing polymeric materials
NASA Technical Reports Server (NTRS)
Peng, S. T. J.
1985-01-01
The constitutive equation for the relaxation behavior of time-dependent, chemically unstable materials developed by Valanis and Peng (1983), which used the irreversible thermodynamics of internal variables in Eyring's absolute reaction theory and yielded a theoretical expression for the effect of chemical crosslink density on the relaxation rate, is presently applied to the creep behavior of a network polymer which is undergoing a scission process. In particular, two equations are derived which may for the first time show the relations between mechanical models and internal variables in the creep expressions, using a three-element model with a Maxwell element.
Biaxial constitutive equation development for single crystals
NASA Technical Reports Server (NTRS)
Jordan, E. H.
1984-01-01
Current gas turbine engines utilize large single crystal superalloy components in the hot section. Structural analysis of these components requires a valid stress strain temperature constitutive equation. The goal of the program described is to create one or more models and verify these models. A constitutive equation based on an assumed slip behavior of a single slip system was formulated, programmed, and debugged. Specifically, the basic theory for a model based on aggravating slip behavior on individual slip systems was formulated and programmed and some simulations were run using assumed values of constants. In addition, a formulation allowing strain controlled simulations was completed. An approach to structural analysis of the specimen was developed. This approach uses long tube consistancy conditions and finite elements specially formulated to take advantage of the symmetry of 100 oriented specimens.
Constitutive equations for an electroactive polymer
NASA Astrophysics Data System (ADS)
Tixier, Mireille; Pouget, Joël
2016-07-01
Ionic electroactive polymers can be used as sensors or actuators. For this purpose, a thin film of polyelectrolyte is saturated with a solvent and sandwiched between two platinum electrodes. The solvent causes a complete dissociation of the polymer and the release of small cations. The application of an electric field across the thickness results in the bending of the strip and vice versa. The material is modeled by a two-phase continuous medium. The solid phase, constituted by the polymer backbone inlaid with anions, is depicted as a deformable porous media. The liquid phase is composed of the free cations and the solvent (usually water). We used a coarse grain model. The conservation laws of this system have been established in a previous work. The entropy balance law and the thermodynamic relations are first written for each phase and then for the complete material using a statistical average technique and the material derivative concept. One deduces the entropy production. Identifying generalized forces and fluxes provides the constitutive equations of the whole system: the stress-strain relations which satisfy a Kelvin-Voigt model, generalized Fourier's and Darcy's laws and the Nernst-Planck equation.
Application of the PTT model to axisymmetric free surface flows
NASA Astrophysics Data System (ADS)
Merejolli, R.; Paulo, G. S.; Tomé, M. F.
2013-10-01
This work is concerned with numerical simulation of axisymmetric viscoelastic free surface flows using the Phan-Thien-Tanner (PTT) constitutive equation. A finite difference technique for solving the governing equations for unsteady incompressible flows written in Cylindrical coordinates on a staggered grid is described. The fluid is modelled by a Marker-and-Cell type method and an accurate representation of the fluid surface is employed. The full free surface stress conditions are applied. The numerical method is verified by comparing numerical predictions of fully developed flow in a pipe with the corresponding analytic solutions. To demonstrate that the numerical method can simulate axisymmetric free surface flows governed by the PTT model, numerical results of the flow evolution of a drop impacting on a rigid dry plate are presented. In these simulations, the rheological effects of the parameters ɛ and ξ are investigated.
Partial thromboplastin time (PTT)
... help the blood clot. This is called the coagulation cascade. The PTT test looks at some of ... control blood clotting become over active ( disseminated intravascular coagulation ) Liver disease Difficulty absorbing nutrients from food ( malabsorption ) ...
Constitutive equations for discrete electromagnetic problems over polyhedral grids
Codecasa, Lorenzo . E-mail: codecasa@elet.polimi.it; Trevisan, Francesco . E-mail: trevisan@uniud.it
2007-08-10
In this paper a novel approach is proposed for constructing discrete counterparts of constitutive equations over polyhedral grids which ensure both consistency and stability of the algebraic equations discretizing an electromagnetic field problem. The idea is to construct discrete constitutive equations preserving the thermodynamic relations for constitutive equations. In this way, consistency and stability of the discrete equations are ensured. At the base, a purely geometric condition between the primal and the dual grids has to be satisfied for a given primal polyhedral grid, by properly choosing the dual grid. Numerical experiments demonstrate that the proposed discrete constitutive equations lead to accurate approximations of the electromagnetic field.
A Constitutive Equation for Stratospheric Balloon Materials
NASA Technical Reports Server (NTRS)
Rand, J. L.; Sterling, W. J.
2004-01-01
The selection of a suitable material for use as a reliable stratospheric balloon gas barrier and structural component is based on a variety of properties. Due to a more desirable combination of properties, the low density polyethylene that has been used for the last half century has been replaced during the last decade by linear low density polyethylene (LLDPE). This paper describes the effort to characterize the time dependent properties of a 38 micron coextrusion of LLDPE. The nonlinear viscoelastic constitutive equation presented may be used to accurately describe the creep and/or relaxation of this film when subjected to a biaxial state of stress, such as might be required for an extended balloon flight. Recent laboratory data have been used to mod@ an existing model of LLDPE to account for differences caused by the coextrusion process. The new model will facilitate structural design optimization and reliability assessment, and may be further utilized as a predictive tool to benefit in-flight operations. Current structural analysis tech&ques based on linear elastic properties have predicted stresses in excess of those which would actually exist.
NASA Astrophysics Data System (ADS)
Dumansky, Alexander M.; Tairova, Lyudmila P.
2008-09-01
A method for the construction of hereditary constitutive equation is proposed for the laminate on the basis of hereditary constitutive equations of a layer. The method is developed from the assumption that in the directions of axes of orthotropy the layer follows elastic behavior, and obeys hereditary constitutive equations under shear. The constitutive equations of the laminate are constructed on the basis of classical laminate theory and algebra of resolvent operators. Effective matrix algorithm and relationships of operator algebra are used to derive visco-elastic stiffness and compliance of the laminate. The example of construction of hereditary constitutive equations of cross-ply carbon fiber-reinforced plastic is presented.
Thermodynamic restrictions on the constitutive equations of electromagnetic theory
NASA Technical Reports Server (NTRS)
Coleman, B. D.; Dill, E. H.
1971-01-01
Thermodynamics second law restrictions on constitutive equations of electromagnetic theory for nonlinear materials with long-range gradually fading memory, considering dissipation principle consequences
Constitutive equations for meeting elevated-temperature-design needs
Pugh, C.E.; Robinson, D.N.
1981-01-01
Constitutive equations for representing the inelastic behavior of structural alloys at temperatures in the creep regime are discussed from the viewpoint of advances made over the past decade. An emphasis is placed on the progress that has been made in meeting the needs of the program whose design process is based in part on a design-by-inelastic-analysis approach. In particular, the constitutive equations that have been put into place for current use in design analyses are discussed along with some material behavior background information. Equations representing short-term plastic and long-term creep behaviors are considered. Trends towards establishing improved equations for use in the future are also described. Progress relating to fundamentals of continuum mechanics, physical modeling, phenomenological modeling, and implementation is addressed.
New constitutive equation for the volume viscosity in fluids
NASA Technical Reports Server (NTRS)
Zuckerwar, Allan J.; Ash, Robert L.
1994-01-01
The traditional volume viscosity, Stokes' hypothesis, and acoustical relaxation are reviewed. The lossy Navier-Stokes Equation is applied to periodic (acoustic) flow, and it is shown that the traditional volume viscosity leads to a result which contradicts that describing acoustical relaxation. It is demonstrated that the addition of a second volume viscosity term to the constitutive equation, to account for pressure relaxation, resolves the conflict, and leads to a direct correspondence between the volume viscosity parameters and the acoustical relaxation parameters. The representation of volume viscosity is formulated for the case of multiple relaxations, as occur in air. Finally, an application of the new constitutive equation to a simple convective compressible flow, namely a linearly accelerating flow, demonstrates the impact of volume viscosity upon the flow and the physical conditions for which it is important.
Generalized constitutive equations for piezo-actuated compliant mechanism
NASA Astrophysics Data System (ADS)
Cao, Junyi; Ling, Mingxiang; Inman, Daniel J.; Lin, Jin
2016-09-01
This paper formulates analytical models to describe the static displacement and force interactions between generic serial-parallel compliant mechanisms and their loads by employing the matrix method. In keeping with the familiar piezoelectric constitutive equations, the generalized constitutive equations of compliant mechanism represent the input-output displacement and force relations in the form of a generalized Hooke’s law and as analytical functions of physical parameters. Also significantly, a new model of output displacement for compliant mechanism interacting with piezo-stacks and elastic loads is deduced based on the generalized constitutive equations. Some original findings differing from the well-known constitutive performance of piezo-stacks are also given. The feasibility of the proposed models is confirmed by finite element analysis and by experiments under various elastic loads. The analytical models can be an insightful tool for predicting and optimizing the performance of a wide class of compliant mechanisms that simultaneously consider the influence of loads and piezo-stacks.
Generalized constitutive equations for piezo-actuated compliant mechanism
NASA Astrophysics Data System (ADS)
Cao, Junyi; Ling, Mingxiang; Inman, Daniel J.; Lin, Jin
2016-09-01
This paper formulates analytical models to describe the static displacement and force interactions between generic serial-parallel compliant mechanisms and their loads by employing the matrix method. In keeping with the familiar piezoelectric constitutive equations, the generalized constitutive equations of compliant mechanism represent the input–output displacement and force relations in the form of a generalized Hooke’s law and as analytical functions of physical parameters. Also significantly, a new model of output displacement for compliant mechanism interacting with piezo-stacks and elastic loads is deduced based on the generalized constitutive equations. Some original findings differing from the well-known constitutive performance of piezo-stacks are also given. The feasibility of the proposed models is confirmed by finite element analysis and by experiments under various elastic loads. The analytical models can be an insightful tool for predicting and optimizing the performance of a wide class of compliant mechanisms that simultaneously consider the influence of loads and piezo-stacks.
Constitutive Equation for Polymer Networks with Phonon Fluctuations
NASA Astrophysics Data System (ADS)
Hansen, Rasmus; Hassager, Ole; Skov, Anne Ladegaard
2008-07-01
Recent research by Xing et al. [Phys. Rev. Lett. 98, 075502, 2007] has provided an expression for the Helmholtz free energy related to phonon fluctuations in polymer networks. We extend this result by constructing the corresponding nonlinear constitutive equation, usable for entirely general, volume conserving deformation fields. Constitutive equations for the sliplink and the tube model are applied. The three models are examined by comparison with each other and with data from Xu and Mark [Rubber Chem. Technol. 63, 276, 1990] and Wang and Mark [J. Polym. Sci. Part B: Polym. Phys. 30, 801, 1992] on end-linked polydimethylsiloxane networks. Elastic moduli are derived for the three models and compared with the moduli determined from the chemical stoichiometry. We conclude that the sliplink model and the phonon fluctuation model are relatively consistent with each other and also with the data. The tube model seems consistent neither with the other models nor with the data.
An inelastic constitutive equation of fiber reinforced plastic laminates
Kanagawa, Y.; Murakami, S.; Mizobe, T.
1998-01-01
A constitutive model for describing the time-dependent inelastic deformation of unidirectional and symmetric angle-ply CFRP (carbon Fiber Reinforced Plastics) laminates is developed. The kinematic hardening creep law of Malinin and Khadjinsky and the evolution equation of Armstrong and Frederick are extended to describe the creep deformation of initially anisotropic materials. In particular, the evolution equations of the back stresses of the anisotropic material were formulated by introducing a transformed strain tensor, by which the expression of the equivalent strain rate of the anisotropic material has the identical form as that of the isotropic materials. The resulting model is applied to analyze the time-dependent inelastic deformation of symmetric angle-ply laminates. Comparison between the predictions and the experimental observations shows that the present model can describe well the time-dependent inelastic behavior under different loadings.
Constitutive equations for coupled flows in clay materials
NASA Astrophysics Data System (ADS)
Revil, A.; Woodruff, W. F.; Lu, N.
2011-05-01
We first upscale the local transport (Stokes and Nernst-Planck) equations to the scale of a single capillary saturated by a binary 1:1 electrolyte. These equations are then upscaled to the scale of a network of tortuous capillaries embedded in a homogeneous and continuous mineral matrix, including the influence of the distribution of pore sizes but excluding the effect of connectivity between the pores. One of the features of our theory is to account for transport along the mineral surface in the so-called Stern layer because of recent evidence that this mechanism is effective in describing frequency-dependent electrical conductivity. Real clay materials are, however, not described by a set of capillaries, so we have to modify the model to include the effect of transversal dispersivity, for example. We found no evidence for transport in the Stern layer because of the discontinuity of the solid phase at the scale of a representative elementary volume in clay materials. The effect of the diffuse layer is accounted for through the use of a Donnan equilibrium approach to determine the effective concentrations of the ions in the pore space, which are different from the ionic concentrations of an ionic reservoir in local equilibrium with the porous material. We found that the diffuse layer controls various transport properties, including, for example, the DC electrical conductivity, the osmotic efficiency coefficient, the streaming potential coupling coefficient, and the macroscopic Hittorf numbers. Comparison to a large data set of experimental data, mainly on clay materials, confirms the validity of the derived relationships used to describe the material properties entering into the constitutive equations.
NASA Astrophysics Data System (ADS)
Jalali, A.; Hulsen, M. A.; Norouzi, M.; Kayhani, M. H.
2013-05-01
This paper presents a numerical simulation of the developing flow and heat transfer of a viscoelastic fluid in a rectangular duct. In fully developed flow of a viscoelastic fluid in a non-circular duct, secondary flows normal to the flow direction are expected to enhance the rate of heat and mass transfer. On the other hand, properties such as viscosity, thermal conductivity, specific heat and relaxation time of the fluid are a function of temperature. Therefore, we developed a numerical model which solves the flow and energy equation simultaneously in three dimensional form. We included several equations of state to model the temperature dependency of the fluid parameters. The current paper is one of the first studies which present a 3D numerical simulation for developing viscoelastic duct flow that takes the dependency of flow parameters to the temperature into account. The rheological constitutive equation of the fluid is a common form of the Phan-Thien Tanner (PTT) model, which embodies both influences of elasticity and shear thinning in viscosity. The governing equations are discretized using the FTCS finite difference method on a staggered mesh. The marker-and-cell method is also employed to allocate the parameters on the staggered mesh, and static pressure is calculated using the artificial compressibility approach during the numerical simulation. In addition to report the results of flow and heat transfer in the developing region, the effect of some dimensionless parameters on the flow and heat transfer has also been investigated. The results are in a good agreement with the results reported by others in this field.
The structure of constitutive equations for semiconductor devices
Buchanan, G.R.; Girrens, S.P.; Bennett, J.G.
1987-01-01
The fundamental equations that describe carrier transport in semiconductor materials are developed using the methods of continuum mixture theory and Maxwell's equations for electrodynamics. There are five basic equations that govern the behavior of current flux, electrostatic potential, electrons, and holes. The bahavior of the electrical chemical potentials are introduced and their relation to the current flux is discussed.
Physical concepts in the development of constitutive equations
NASA Technical Reports Server (NTRS)
Cassenti, B. N.
1985-01-01
Proposed viscoplastic material models include in their formulation observed material response but do not generally incorporate principles from thermodynamics, statistical mechanics, and quantum mechanics. Numerous hypotheses were made for material response based on first principles. Many of these hypotheses were tested experimentally. The proposed viscoplastic theories and the experimental basis of these hypotheses must be checked against the hypotheses. The physics of thermodynamics, statistical mechanics and quantum mechanics, and the effects of defects, are reviewed for their application to the development of constitutive laws.
A comparative study of different ferrofluid constitutive equations.
NASA Astrophysics Data System (ADS)
Kaloni, Purna
2011-11-01
Ferrofluids are stable colloidal suspensions of fine ferromagnetic monodomain nanoparticles in a non-conducting carrier fluid. The particles are coated with a surfacant to avoid agglomeration and coagulation.Brownian motion keeps the nanoparticles from settling under gravity. In recent years these fluids have found several applications including in liquid seals in rotary shafts for vacuum system and in hard disk drives of personal computers, in cooling and damping of loud speakers, in shock absorbers and in biomedical applications. A continuum description of ferrofluids was initiated by Neuringer and Rosensweig but the theory had some limitations. In subsequent years,several authors have proposed generalization of the above theory.Some of these are based upon the internal particle rotation concept, some are phemonological, some are based upon a thermodynamic framework, some employ statistical approach and some have used the dynamic mean field approach. The results based upon these theories ane in early stages and inconclusive. Our purpose is, first, to critically examine the basic foundations of these equations and then study the pedictions obtained in all the theories related to an experimental as well as a theoretical study.
Finite element analysis of notch behavior using a state variable constitutive equation
NASA Technical Reports Server (NTRS)
Dame, L. T.; Stouffer, D. C.; Abuelfoutouh, N.
1985-01-01
The state variable constitutive equation of Bodner and Partom was used to calculate the load-strain response of Inconel 718 at 649 C in the root of a notch. The constitutive equation was used with the Bodner-Partom evolution equation and with a second evolution equation that was derived from a potential function of the stress and state variable. Data used in determining constants for the constitutive models was from one-dimensional smooth bar tests. The response was calculated for a plane stress condition at the root of the notch with a finite element code using constant strain triangular elements. Results from both evolution equations compared favorably with the observed experimental response. The accuracy and efficiency of the finite element calculations also compared favorably to existing methods.
The form of a constitutive equation of plastic deformation compatible with stress relaxation data
Fortes, M.A.; Rosa, M.E.
1984-05-01
Hart's approach to constitutive equations of plasticity and experimental results relevant to his formalism are reanalyzed, with special emphasis on the consequences of the scaling relation observed in the relaxation curves of a large number of materials. Complete constitutive equations containing a single structure variable are proposed which describe the experimentally determined relaxation and tensile test curves. An interpretation of the structure variable is given in terms of the density of obstacles to dislocations. The equations are generalized to include recovery and applied to dislocation creep.
On Eulerian constitutive equations for modeling growth and residual stresses in arteries.
Volokh, K Y
2005-06-01
Recently Volokh and Lev (2005) argued that residual stresses could appear in growing arteries because of the arterial anisotropy. This conclusion emerged from a continuum mechanics theory of growth of soft biological tissues proposed by the authors. This theory included Lagrangian constitutive equations, which were formulated directly with respect to the reference configuration. Alternatively, it is possible to formulate Eulerian constitutive equations with respect to the current configuration and to 'pull them back' to the reference configuration. Such possibility is examined in the present work. The Eulerian formulation of the constitutive equations is used for a study of arterial growth. It is shown, particularly, that bending resultants are developed in the ring cross-section of the artery. These resultants may cause the ring opening or closing after cutting the artery in vitro as it is observed in experiments. It is remarkable that the results of the present study, based on the Eulerian constitutive equations, are very similar to the results of Volokh and Lev (2005), based on the Lagrangian constitutive equations. This strengthens the authors' argument that anisotropy is a possible reason for accumulation of residual stresses in arteries. This argument appears to be invariant with respect to the mathematical description.
Using uniaxial pseudorandom stress stimuli to develop soft tissue constitutive equations.
Hoffman, Allen H; Grigg, Peter
2002-01-01
A nonlinear systems identification method was used to develop constitutive equations for soft tissue specimens under uniaxial tension. The constitutive equations are developed from a single test by applying a pseudorandom Gaussian (PGN) stress input to the specimen, measuring the resulting strain, and calculating the Volterra-Wiener kernels. First and second order kernels were developed for two tissues with widely different properties, rat medial collateral knee ligaments, and rat skin. These kernels were used to predict the strain response to a variety of sinusoidal stress inputs. These predicted strains were compared with the measured strain response using the normalized mean squared error (NMSE). Results showed NMSEs in the range of 0.01-0.08 provided that the magnitudes of the applied stresses were present in the original PGN stress input. Overall, the method provides a means to develop soft tissue constitutive equations that can predict both nonlinear and viscoelastic behavior over a wide range of stress inputs.
Chen, Xi; Fu, Yunqi; Yuan, Naichang
2009-03-01
An approach to design an invisible cloak with controlled constitutive parameters and arbitrary shaped boundaries is presented. Helmholtz's equation is adopted to establish a mapping between original and transformed coordinates inside the cloak. Then the constitutive parameters are obtained by the established mapping. The analytical solution of a regular cloak and the numerical solution of an irregular cloak both verify that that our method will guide electromagnetic wave efficiently and control the constitutive parameters of the cloak conveniently. It has great significance in realizing a cloak practically. PMID:19259197
Phillips, R.J.; Armstrong, R.C.; Brown, R.A. ); Graham, A.L.; Abbott, J.R. )
1992-01-01
A constitutive equation for computing particle concentration and velocity fields in concentrated monomodal suspensions is proposed that consists of two parts: a Newtonian constitutive equation in which the viscosity depends on the local particle volume fraction and a diffusion equation that accounts for shear-induced particle migration. Particle flux expressions used to obtain the diffusion equation are derived by simple scaling arguments. Predictions are made for the particle volume fraction and velocity fields for steady Couette and Poiseuille flow, and for transient start-up of steady shear flow in a Couette apparatus. Particle concentrations for a monomodal suspension of polymethyl methacrylate spheres in a Newtonian solvent are measured by nuclear magnetic resonance (NMR) imaging in the Couette geometry for two particle sizes and volume fractions. The predictions agree remarkably well with the measurements for both transient and steady-state experiments as well as for different particle sizes.
An In-Depth Tutorial on Constitutive Equations for Elastic Anisotropic Materials
NASA Technical Reports Server (NTRS)
Nemeth, Michael P.
2011-01-01
An in-depth tutorial on the constitutive equations for elastic, anisotropic materials is presented. Basic concepts are introduced that are used to characterize materials, and notions about how anisotropic material deform are presented. Hooke s law and the Duhamel-Neuman law for isotropic materials are presented and discussed. Then, the most general form of Hooke s law for elastic anisotropic materials is presented and symmetry requirements are given. A similar presentation is also given for the generalized Duhamel-Neuman law for elastic, anisotropic materials that includes thermal effects. Transformation equations for stress and strains are presented and the most general form of the transformation equations for the constitutive matrices are given. Then, specialized transformation equations are presented for dextral rotations about the coordinate axes. Next, concepts of material symmetry are introduced and criteria for material symmetries are presented. Additionally, engineering constants of fully anisotropic, elastic materials are derived from first principles and the specialized to several cases of practical importance.
NASA Technical Reports Server (NTRS)
1997-01-01
The bibliography contains citations concerning analytical techniques using constitutive equations, applied to materials under stress. The properties explored with these techniques include viscoelasticity, thermoelasticity, and plasticity. While many of the references are general as to material type, most refer to specific metals or composites, or to specific shapes, such as flat plate or spherical vessels.
NASA Technical Reports Server (NTRS)
Robinson, D. N.
1985-01-01
Three major categories of testing are identified that are necessary to provide support for the development of constitutive equations for high temperature alloys. These are exploratory, charactrization and verification tests. Each category is addressed and specific examples of each are given. An extensive, but not exhaustive, set of references is provided concerning pertinent experimental results and their relationships to theoretical development. This guide to formulating a meaningful testing effort in support of consitutive equation development can also aid in defining the necessary testing equipment and instrumentation for the establishment of a deformation and structures testing laboratory.
Diaz, Manuel I.; Aquino, Wilkins; Bonnet, Marc
2015-01-01
This paper presents a methodology for the inverse identification of linearly viscoelastic material parameters in the context of steady-state dynamics using interior data. The inverse problem of viscoelasticity imaging is solved by minimizing a modified error in constitutive equation (MECE) functional, subject to the conservation of linear momentum. The treatment is applicable to configurations where boundary conditions may be partially or completely underspecified. The MECE functional measures the discrepancy in the constitutive equations that connect kinematically admissible strains and dynamically admissible stresses, and also incorporates the measurement data in a quadratic penalty term. Regularization of the problem is achieved through a penalty parameter in combination with the discrepancy principle due to Morozov. Numerical results demonstrate the robust performance of the method in situations where the available measurement data is incomplete and corrupted by noise of varying levels. PMID:26388656
Constitutive Equation for 3104 Alloy at High Temperatures in Consideration of Strain
NASA Astrophysics Data System (ADS)
Zhen, Fuqiang; Sun, Jianlin; Li, Jian
2016-06-01
The flow behavior of 3104 aluminum alloy was investigated at temperatures ranging from 250°C to 500°C, and strain rates from 0.01 to 10 s-1 by isothermal compression tests. The true stress-strain curves were obtained from the measured load-stroke data and then modified by friction and temperature correction. The effects of temperature and strain rate on hot deformation behavior were represented by Zener-Hollomon parameter including Arrhenius term. Additionally, the influence of strain was incorporated considering the effect of strain on material constants. The derived constitution equation was applied to the finite element analysis of hot compression. The results show that the simulated force is consistent with the measured one. Consequently, the developed constitution equation is valid and feasible for numerical simulation in hot deformation process of 3104 alloy.
An anisotropic constitutive equation for the stress tensor of blood based on mixture theory
Massoudi, M.; Antaki, J.
2008-01-01
Based on ideas proposed by Massoudi and Rajagopal M-R , we develop a model for blood using the theory of interacting continua, that is, the mixture theory. We first provide a brief review of mixture theory, and then discuss certain issues in constitutive modeling of a two-component mixture. In the present formulation, we ignore the biochemistry of blood and assume that blood is composed of red blood cells RBCs suspended in plasma, where the plasma behaves as a linearly viscous fluid and the RBCs are modeled as an anisotropic nonlinear density-gradient-type fluid. We obtain a constitutive relation for blood, based on the simplified constitutive relations derived for plasma and RBCs. A simple shear flow is discussed, and an exact solution is obtained for a very special case; for more general cases, it is necessary to solve the nonlinear coupled equations numerically.
An anisotropic constitutive equation for the stress tensor of blood based on mixture theory
Massoudi, Mehrdad; Antaki, J.F.
2008-09-12
Based on ideas proposed by Massoudi and Rajagopal (M-R), we develop a model for blood using the theory of interacting continua, that is, the mixture theory. We first provide a brief review of mixture theory, and then discuss certain issues in constitutive modeling of a two-component mixture. In the present formulation, we ignore the biochemistry of blood and assume that blood is composed of red blood cells (RBCs) suspended in plasma, where the plasma behaves as a linearly viscous fluid and the RBCs are modeled as an anisotropic nonlinear density-gradient-type fluid. We obtain a constitutive relation for blood, based on the simplified constitutive relations derived for plasma and RBCs. A simple shear flow is discussed, and an exact solution is obtained for a very special case; for more general cases, it is necessary to solve the nonlinear coupled equations numerically.
NASA Technical Reports Server (NTRS)
1996-01-01
The bibliography contains citations concerning analytical techniques using constitutive equations, applied to materials under stress. The properties explored with these techniques include viscoelasticity, thermoelasticity, and plasticity. While many of the references are general as to material type, most refer to specific metals or composites, or to specific shapes, such as flat plate or spherical vessels. (Contains 50-250 citations and includes a subject term index and title list.)
Chang, Zheng; Zhou, Xiaoming; Hu, Jin; Hu, Gengkai
2010-02-15
In a recent paper, Chen et al. [Opt. Express 17, 3581 (2009)] develop an approach to design invisible cloaks with controllable constitutive parameters by adjusting the constant k in the Helmholtz's equation. In this comment, we discuss the limitation of the free parameter k in designing cloaks. It is found that the real constant k can be chosen only as limited values in order to avoid the singular material parameters. PMID:20389403
NASA Technical Reports Server (NTRS)
Goldberg, Robert K.; Stouffer, Donald C.
1998-01-01
Recently applications have exposed polymer matrix composite materials to very high strain rate loading conditions, requiring an ability to understand and predict the material behavior under these extreme conditions. In this first paper of a two part report, background information is presented, along with the constitutive equations which will be used to model the rate dependent nonlinear deformation response of the polymer matrix. Strain rate dependent inelastic constitutive models which were originally developed to model the viscoplastic deformation of metals have been adapted to model the nonlinear viscoelastic deformation of polymers. The modified equations were correlated by analyzing the tensile/ compressive response of both 977-2 toughened epoxy matrix and PEEK thermoplastic matrix over a variety of strain rates. For the cases examined, the modified constitutive equations appear to do an adequate job of modeling the polymer deformation response. A second follow-up paper will describe the implementation of the polymer deformation model into a composite micromechanical model, to allow for the modeling of the nonlinear, rate dependent deformation response of polymer matrix composites.
Skontorp, A.; Wang, S.S.; Shibuya, Y.
1994-12-31
In this paper, a homogenization theory is developed to determine high-temperature effective viscoelastic constitutive equations for fiber-reinforced polymer composites. The homogenization theory approximates the microstructure of a fiber composite, and determine simultaneously effective macroscopic constitutive properties of the composite and the associated microscopic strain and stress in the heterogeneous material. The time-temperature dependent homogenization theory requires that the viscoelastic constituent properties of the matrix phase at elevated temperatures, the governing equations for the composites, and the boundary conditions of the problem be Laplace transformed to a conjugate problem. The homogenized effective properties in the transformed domain are determined, using a two-scale asymptotic expansion of field variables and an averaging procedure. Field solutions in the unit cell are determined from basic and first-order governing equations with the aid of a boundary integral method (BIM). Effective viscoelastic constitutive properties of the composite at elevated temperatures are determined by an inverse transformation, as are the microscopic stress and deformation in the composite. Using this method, interactions among fibers and between the fibers and the matrix can be evaluated explicitly, resulting in accurate solutions for composites with high-volume fraction of reinforcing fibers. Examples are given for the case of a carbon-fiber reinforced thermoplastic polyamide composite in an elevated temperature environment. The homogenization predictions are in good agreement with experimental data available for the composite.
A Modified Johnson-Cook Constitutive Equation to Predict Hot Deformation Behavior of Ti-6Al-4V Alloy
NASA Astrophysics Data System (ADS)
Cai, Jun; Wang, Kuaishe; Zhai, Peng; Li, Fuguo; Yang, Jie
2014-09-01
A modified Johnson-Cook constitutive equation of Ti-6Al-4V alloy is proposed based on hot compression tests performed in the temperature range of 1073-1323 K and strain rate 0.001-1 s-1. The experimental stress-strain data were employed to develop the modified Johnson-Cook constitutive equation of different phase regimes (α + β and β phase). The predicted flow stresses using the developed equation were compared with experimental data. Correlation coefficient (R) and average absolute relative error (AARE) were introduced to verify the validity of the constitutive equation. The values of R and AARE for α + β phase were 0.990 and 7.81%, respectively. And in β phase region, the values of R and AARE were 0.985 and 10.36%, respectively. Meanwhile, the accuracy, the number of material constants involved, and the computational time required of the constitutive equation were evaluated by comparing with a strain-compensated Arrhenius-type constitutive equation. The results indicate that accuracy of modified Johnson-Cook constitutive equation is higher than that of compensated Arrhenius-type model at α + β phase, while lower at single β phase region. Meanwhile, the time required for evaluating the material constants of modified Johnson-Cook constitutive equation is much shorter than that of the strain-compensated Arrhenius type ones.
A Modified Johnson-Cook Constitutive Equation to Predict Hot Deformation Behavior of Ti-6Al-4V Alloy
NASA Astrophysics Data System (ADS)
Cai, Jun; Wang, Kuaishe; Zhai, Peng; Li, Fuguo; Yang, Jie
2015-01-01
A modified Johnson-Cook constitutive equation of Ti-6Al-4V alloy is proposed based on hot compression tests performed in the temperature range of 1073-1323 K and strain rate 0.001-1 s-1. The experimental stress-strain data were employed to develop the modified Johnson-Cook constitutive equation of different phase regimes (α + β and β phase). The predicted flow stresses using the developed equation were compared with experimental data. Correlation coefficient ( R) and average absolute relative error (AARE) were introduced to verify the validity of the constitutive equation. The values of R and AARE for α + β phase were 0.990 and 7.81%, respectively. And in β phase region, the values of R and AARE were 0.985 and 10.36%, respectively. Meanwhile, the accuracy, the number of material constants involved, and the computational time required of the constitutive equation were evaluated by comparing with a strain-compensated Arrhenius-type constitutive equation. The results indicate that accuracy of modified Johnson-Cook constitutive equation is higher than that of compensated Arrhenius-type model at α + β phase, while lower at single β phase region. Meanwhile, the time required for evaluating the material constants of modified Johnson-Cook constitutive equation is much shorter than that of the strain-compensated Arrhenius type ones.
A Unified Constitutive Equation of a Bainite Steel During Hot Deformation
NASA Astrophysics Data System (ADS)
Li, Lixin; Ye, Ben; Liu, Sheng; Hu, Shengde; Liao, Hanqing
2016-10-01
A constitutive model has been established based on dislocation theory, work hardening and dynamic recovery theory, and softening mechanisms of dynamic recrystallization. The stress-strain curves of a bainite steel have been measured with hot compression experiments at temperatures of 1173, 1273, 1373 and 1473 K with strain rates of 0.01, 0.1, 1 and 10 s-1 on a thermo-mechanical simulator (Gleeble-1500). The material constants involved in the constitutive model have been optimized by an inverse analysis of the stress-strain curves using the method of coordinate rotation, determining the strain-stress relationship or the constitutive equation, the kinetic models of dynamic recovery and dynamic recrystallization, and a few material constants of the investigated steel. Comparison of the calculated flow stress with the experimental data suggests that the relationship between the flow stress and the strain rate, temperature, strain of the steel during hot deformation can be described by the constitutive model, and that the underlying materials science can be captured from the material constants determined by the stress-strain curves.
A Unified Constitutive Equation of a Bainite Steel During Hot Deformation
NASA Astrophysics Data System (ADS)
Li, Lixin; Ye, Ben; Liu, Sheng; Hu, Shengde; Liao, Hanqing
2016-08-01
A constitutive model has been established based on dislocation theory, work hardening and dynamic recovery theory, and softening mechanisms of dynamic recrystallization. The stress-strain curves of a bainite steel have been measured with hot compression experiments at temperatures of 1173, 1273, 1373 and 1473 K with strain rates of 0.01, 0.1, 1 and 10 s-1 on a thermo-mechanical simulator (Gleeble-1500). The material constants involved in the constitutive model have been optimized by an inverse analysis of the stress-strain curves using the method of coordinate rotation, determining the strain-stress relationship or the constitutive equation, the kinetic models of dynamic recovery and dynamic recrystallization, and a few material constants of the investigated steel. Comparison of the calculated flow stress with the experimental data suggests that the relationship between the flow stress and the strain rate, temperature, strain of the steel during hot deformation can be described by the constitutive model, and that the underlying materials science can be captured from the material constants determined by the stress-strain curves.
On the use of internal state variables in thermoviscoplastic constitutive equations
NASA Technical Reports Server (NTRS)
Allen, D. H.; Beek, J. M.
1985-01-01
The general theory of internal state variables are reviewed to apply it to inelastic metals in use in high temperature environments. In this process, certain constraints and clarifications will be made regarding internal state variables. It is shown that the Helmholtz free energy can be utilized to construct constitutive equations which are appropriate for metallic superalloys. Internal state variables are shown to represent locally averaged measures of dislocation arrangement, dislocation density, and intergranular fracture. The internal state variable model is demonstrated to be a suitable framework for comparison of several currently proposed models for metals and can therefore be used to exhibit history dependence, nonlinearity, and rate as well as temperature sensitivity.
Constitutive Equations for Use in Design Analyses of Long-life Elevated Temperature Components
NASA Technical Reports Server (NTRS)
Pugh, C. E.; Robinson, D. N.
1983-01-01
Design analysis needs and procedures relative to elevated temperature components in liquid metal fast breeder reactor (LMFBR) system were examined. The effects of the thermal transients on the pressure boundary components are enhanced by the excellent heat transfer properties of the liquid sodium coolant. Design criteria for high temperature nuclear reactor components recognize the potential occurrence of inelastic structural response. Specifically, criteria and limits were developed which reflect a recognition of this potential and employ design by analysis concepts that requires that inelastic (elastic-plastic and creep) analyses be performed. Constitutive equations to represent multiaxial time-dependent responses of LMFBR alloys are established. The development of equations applicable under cyclic loading conditions are outlined.
A Potential Function Derivation of a Constitutive Equation for Inelastic Material Response
NASA Technical Reports Server (NTRS)
Stouffer, D. C.; Elfoutouh, N. A.
1983-01-01
Physical and thermodynamic concepts are used to develop a potential function for application to high temperature polycrystalline material response. Inherent in the formulation is a differential relationship between the potential function and constitutive equation in terms of the state variables. Integration of the differential relationship produces a state variable evolution equation that requires specification of the initial value of the state variable and its time derivative. It is shown that the initial loading rate, which is directly related to the initial hardening rate, can significantly influence subsequent material response. This effect is consistent with observed material behavior on the macroscopic and microscopic levels, and may explain the wide scatter in response often found in creep testing.
NASA Astrophysics Data System (ADS)
Wang, K.; Liu, F. C.; Xue, P.; Wang, D.; Xiao, B. L.; Ma, Z. Y.
2016-01-01
Fifteen Al-Mg-Sc samples with subgrain/grain sizes in the range of 1.8 to 4.9 μm were prepared through the processing methods of friction stir processing (FSP), equal-channel-angular pressing (ECAP), rolling, annealing, and combinations of the above. The percentages of high-angle grain boundaries (HAGBs) of these fine-grained alloys were distributed from 39 to 97 pct. The samples processed through FSP had a higher percentage of HAGBs compared to other samples. Superplasticity was achieved in all fifteen samples, but the FSP samples exhibited better superplasticity than other samples because their fine equiaxed grains, which were mostly surrounded by HAGBs, were conducive to the occurrence of grain boundary sliding (GBS) during superplastic deformation. The dominant deformation mechanism was the same for all fifteen samples, i.e., GBS controlled by grain boundary diffusion. However, the subgrains were the GBS units for the rolled or ECAP samples, which contained high percentages of unrecrystallized grains, whereas the fine grains were the GBS units for the FSP samples. Superplastic data analysis revealed that the dimensionless A in the classical constitutive equation for superplasticity of fine-grained Al alloys was not a constant, but increased with an increase in the percentage of HAGBs, demonstrating that the enhanced superplastic deformation kinetics can be ascribed to the high percentage of HAGBs. A modified superplastic constitutive equation with the percentage of HAGBs as a new microstructural parameter was established.
Parameter correlation of high-temperature creep constitutive equation for RPV metallic materials
NASA Astrophysics Data System (ADS)
Xie, Lin-Jun; Ren, Xin; Shen, Ming-Xue; Tu, Li-Qun
2015-10-01
Constant-temperature and constant-load creep tests of SA-508 stainless steel were performed at six temperatures, and the creep behavior and properties of this material were determined. Constitutive models were established based on an isothermal creep method to describe the high-temperature creep behavior of SA-508. Material parameter k, stress exponent nσ, and temperature exponent nt of the established constitutive models were determined through experimental data via numerical optimization techniques. The relationship of k, nσ, and nt was evaluated, and a new coefficient model of k-T, nσ-T, nt-T, and nt-nσ was formulated through the parameters of the isothermal creep equation. Moreover, the isothermal creep equation for this material at every temperature point from 450 °C to 1000 °C was obtained from the models. This method can serve as a reference for isothermal creep analysis and provide a way for the safety assessment of components of reactor pressure vessels.
NASA Astrophysics Data System (ADS)
Dong, Yuanyuan; Zhang, Cunsheng; Lu, Xing; Wang, Cuixue; Zhao, Guoqun
2016-06-01
A reasonable constitutive model is the key to achieving the accurate numerical simulation of magnesium alloy extrusion process. Based on the hot compression tests of the as-extruded AZ31 magnesium alloy, the strain-compensated Arrhenius equation, the constitutive equation taking into account dynamic recovery (DRV) and dynamic recrystallization (DRX), and the modified Fields-Backofen equation (FB) are established to describe the deformation behavior of this alloy under large strain condition (strain level greater than 1.0) and wide strain rate range (0.01 to 10 s-1), respectively. Then material parameters in each constitutive model are determined by linear fitting method. The comparison of these three kinds of equations shows that the strain-compensated Arrhenius model provides the best prediction of flow stress, and the calculated value of correlation coefficient ( R) is the highest as 0.9945 and the average absolute relative error (AARE) is the lowest as 3.11%. The constitutive equation with DRV + DRX can also predict flow stress accurately, and its values of R and AARE are 0.9920 and 4.41%, respectively. However, compared to the other two constitutive equations, the modified FB equation does not give good description of hot deformation behavior for this magnesium alloy. Finally, the advantages and drawbacks of these three kinds of constitutive models are discussed and compared. Therefore, this work could provide theoretical guidelines for investigating hot deformation behavior of wrought magnesium alloys and determining the appropriate extrusion process parameters under large strain condition.
Klisch, Stephen M
2006-06-01
Cartilaginous tissues, such as articular cartilage and the annulus fibrosus, exhibit orthotropic behavior with highly asymmetric tensile-compressive responses. Due to this complex behavior, it is difficult to develop accurate stress constitutive equations that are valid for finite deformations. Therefore, we have developed a bimodular theory for finite deformations of elastic materials that allows the mechanical properties of the tissue to differ in tension and compression. In this paper, we derive an orthotropic stress constitutive equation that is second-order in terms of the Biot strain tensor as an alternative to traditional exponential type equations. Several reduced forms of the bimodular second-order equation, with six to nine parameters, and a bimodular exponential equation, with seven parameters, were fit to an experimental dataset that captures the highly asymmetric and orthotropic mechanical response of cartilage. The results suggest that the bimodular second-order models may be appealing for some applications with cartilaginous tissues.
Hot Compression of TC8M-1: Constitutive Equations, Processing Map, and Microstructure Evolution
NASA Astrophysics Data System (ADS)
Yue, Ke; Chen, Zhiyong; Liu, Jianrong; Wang, Qingjiang; Fang, Bo; Dou, Lijun
2016-06-01
Hot compression of TC8M-1 was carried out under isothermal working conditions with temperature from 1173 K to 1323 K (900 °C to 1050 °C), strain rate from 0.001 to 10/s, and height reduction from 20 to 80 pct (corresponding true strain from 0.22 to 1.61). Constitutive equations were constructed and apparent activation energies of 149.5 and 617.4 kJ/mol were obtained for deformation in the β and upper α/ β phase regions, respectively. Microstructure examination confirmed the dominant role of dynamic recrystallization in the α/ β phase region and that of dynamic recovery in the β phase region, with the occurrence of grain boundary sliding at very low strain rate (0.001/s) in both regions. Based on the dynamic materials model, processing maps were constructed, providing optimal domains for hot working at the temperature of 1253 K (980 °C) and the strain rate of 0.01 to 0.1/s, or at 1193 K to 1213 K (920 °C to 940 °C) and 0.001/s. Moreover, our results indicated that the initial temperature non-uniformity along the specimen axis before compression existed and influenced the strain distribution, which contributed to the abnormal oscillations and/or abrupt rise-up of true stress and inhomogeneous deformation.
Rheological behavior and constitutive equations of heterogeneous titanium-bearing molten slag
NASA Astrophysics Data System (ADS)
Jiang, Tao; Liao, De-ming; Zhou, Mi; Zhang, Qiao-yi; Yue, Hong-rui; Yang, Song-tao; Duan, Pei-ning; Xue, Xiang-xin
2015-08-01
Experimental studies on the rheological properties of a CaO-SiO2-Al2O3-MgO-TiO2-(TiC) blast furnace (BF) slag system were conducted using a high-temperature rheometer to reveal the non-Newtonian behavior of heterogeneous titanium-bearing molten slag. By measuring the relationships among the viscosity, the shear stress and the shear rate of molten slags with different TiC contents at different temperatures, the rheological constitutive equations were established along with the rheological parameters; in addition, the non-Newtonian fluid types of the molten slags were determined. The results indicated that, with increasing TiC content, the viscosity of the molten slag tended to increase. If the TiC content was less than 2wt%, the molten slag exhibited the Newtonian fluid behavior when the temperature was higher than the critical viscosity temperature of the molten slag. In contrast, the molten slag exhibited the non-Newtonian pseudoplastic fluid characteristic and the shear thinning behavior when the temperature was less than the critical viscosity temperature. However, if the TiC content exceeded 4wt%, the molten slag produced the yield stress and exhibited the Bingham and plastic pseudoplastic fluid behaviors when the temperature was higher and lower than the critical viscosity temperature, respectively. When the TiC content increased further, the yield stress of the molten slag increased and the shear thinning phenomenon became more obvious.
NASA Astrophysics Data System (ADS)
Kishor, Brij; Chaudhari, G. P.; Nath, S. K.
2016-07-01
Hot compression tests were performed to study the hot deformation characteristics of 13Cr-4Ni stainless steel. The tests were performed in the strain rate range of 0.001-10 s-1 and temperature range of 900-1100 °C using Gleeble® 3800 simulator. A constitutive equation of Arrhenius type was established based on the experimental data to calculate the different material constants, and average value of apparent activation energy was found to be 444 kJ/mol. Zener-Hollomon parameter, Z, was estimated in order to characterize the flow stress behavior. Power dissipation and instability maps developed on the basis of dynamic materials model for true strain of 0.5 show optimum hot working conditions corresponding to peak efficiency range of about 28-32%. These lie in the temperature range of 950-1025 °C and corresponding strain rate range of 0.001-0.01 s-1 and in the temperature range of 1050-1100 °C and corresponding strain rate range of 0.01-0.1 s-1. The flow characteristics in these conditions show dynamic recrystallization behavior. The microstructures are correlated to the different stability domains indicated in the processing map.
NASA Astrophysics Data System (ADS)
Zhang, Chi; Zhang, Liwen; Shen, Wenfei; Li, Mengfei; Gu, Sendong
2015-01-01
In order to clarify the microstructural evolution and workability of Hastelloy C-276 during hot forming to get excellent mechanical properties, the hot deformation behavior of this superalloy is characterized. The cylindrical specimens were isothermal compressed in the temperature range of 1000-1200 °C and strain rate range of 0.001-5 s-1 on a Gleeble 1500 thermal-mechanical simulator. The flow curves and microstructural investigation indicates that dynamic recrystallization is the prime softening mechanism at the evaluated deformation conditions. The constitutive equation was presented as a function of the deformation temperature, strain rate, and strain, and the deformation activation energy was about 450 kJ/mol. The processing maps based on dynamic materials model at the strains of 0.2, 0.4, 0.6, 0.8, and 1.0 were established, and the processing map at 1.0 strain shows good correspondence to the microstructural observation. The domains in processing map in which the efficiency of power dissipation (η) is higher than 0.25 are corresponding to sufficient dynamic recyrstallization phenomenon, which are suggested to be the optimum working areas for Hastelloy C-276.
NASA Astrophysics Data System (ADS)
Yoshimoto, Akifumi; Kobayashi, Hidetoshi; Horikawa, Keitaro; Tanigaki, Kenichi
2015-09-01
These days, polymer foams, such as polyurethane foam and polystyrene foam, are used in various situations as a thermal insulator or shock absorber. In general, however, their strength is insufficient in high temperature environments because of their low glass transition temperature. Polyimide is a polymer which has a higher glass transition temperature and high strength. Its mechanical properties do not vary greatly, even in low temperature environments. Therefore, polyimide foam is expected to be used in the aerospace industry. Thus, the constitutive equation of polyimide foam that can be applied across a wide range of strain rates and ambient temperature is very useful. In this study, a series of compression tests at various strain rates, from 10-3 to 103 s-1 were carried out in order to examine the effect of strain rate on the compressive properties of polyimide foam. The flow stress of polyimide foam increased rapidly at dynamic strain rates. The effect of ambient temperature on the properties of polyimide foam was also investigated at temperature from - 190 °C to 270°∘C. The flow stress decreased with increasing temperature.
NASA Astrophysics Data System (ADS)
Mae, H.
2006-08-01
The strong strain-rate dependence, neck propagation and craze evolution characterize the large plastic deformation and fracture behavior of polymer. In the latest study, Kobayashi, Tomii and Shizawa suggested the elastoviscoplastic constitutive equation based on craze evolution and annihilation and then applied it to the plane strain issue of polymer. In the previous study, the author applied their suggested elastoviscoplastic constitutive equation with craze effect to the three dimensional shell and then showed that the load displacement history was in good agreement with the experimental result including only microscopic crack such as crazes. For the future industrial applications, the macroscopic crack has to be taken into account. Thus, the main objective of this study is to propose the tensile softening equation and then add it to the elastoviscoplastic constitutive equation with craze effect so that the load displacement history can be roughly simulated during the macroscopic crack propagation. The tested material in this study is the elastomer blended polypropylene used in the interior and exterior of automobiles. First, the material properties are obtained based on the tensile test results at wide range of strain rates: 10 - 4-102 (1/sec). Next, the compact tension test is conducted and then the tensile softening parameters are fixed. Then, the dart impact test is carried out in order to obtain the load displacement history and also observe the macroscopic crack propagation at high strain rate. Finally, the fracture behavior is simulated and then compared with the experimental results. It is shown that the predictions of the constitutive equation with the proposed tensile softening equation are in good agreement with the experimental results for the future industrial applications.
Zhu, Meiling; Leighton, Glenn
2008-11-01
Accurate performance evaluation is crucial to the design and development of macro/micro-sized piezoelectric devices, and key to this is the proper use of the stiffness/ compliance and piezoelectric coefficients of the piezoelectric ceramics involved. Although the literature points out effective piezoelectric coefficients e(31,f) and d(33,f) for thin film materials and reduced dimensionality of equations for bulk material, the elastic and piezoelectric coefficients remain unchanged from the 3-D equations in most reported 1-D and 2-D analyses of the macro/micro-sized devices involving the e form of the constitutive equations. The use of unchanged coefficients leads to variations between numerically predicted and experimental results in most devices. To understand effects of the dimensional reduction from 3-D to 2-D and 1-D on stiffness/compliance and piezoelectric coefficients, this paper derives the 2-D and 1-D constitutive equations from the 3-D equations, focusing on the discussion of often-required device configurations for sensor and actuator design and analysis. Two modified coefficients are proposed, termed reduced and enhanced, which enable better understanding of effects of the dimensional reduction and also effects on the design and analysis of sensors and actuators.
NASA Astrophysics Data System (ADS)
Hussain, Mirza Zahid; Li, Fuguo; Wang, Jing; Yuan, Zhanwei; Li, Pan; Wu, Tao
2015-07-01
The present study comprises the determination of constitutive relationship for thermo-mechanical processing of INCONEL 718 through double multivariate nonlinear regression, a newly developed approach which not only considers the effect of strain, strain rate, and temperature on flow stress but also explains the interaction effect of these thermo-mechanical parameters on flow behavior of the alloy. Hot isothermal compression experiments were performed on Gleeble-3500 thermo-mechanical testing machine in the temperature range of 1153 to 1333 K within the strain rate range of 0.001 to 10 s-1. The deformation behavior of INCONEL 718 is analyzed and summarized by establishing the high temperature deformation constitutive equation. The calculated correlation coefficient ( R) and average absolute relative error ( AARE) underline the precision of proposed constitutive model.
NASA Astrophysics Data System (ADS)
Jomaa, Walid; Songmene, Victor; Bocher, Philippe
2016-03-01
In recent years, there has been growing interest for the identification of material constitutive equations using machining tests (inverse method). However, the inverse method has shown some drawbacks that could affect the accuracy of the identified material constants. On one hand, this approach requires the use of analytical model to estimate the cutting temperature. Nevertheless, the used temperature models lead to large discrepancies for the calculated temperatures even for the same work material and cutting conditions. On the other hand, some computation issues were observed when all material constants were determined, in the same time, using machining tests data. Therefore, this study attempts to provide a methodology for identifying the coefficients of the Marusich's constitutive equation (MCE) which demonstrated a good capability for the simulation of the material behavior in high speed machining. The proposed approach, which is based on an analytical inverse method together with dynamic tests, was applied to aluminum alloys AA6061-T6 and AA7075-T651, and induction hardened AISI 4340 steel (60 HRC). The response surface methodology was used in this approach. Two sets of material coefficients, for each tested work material, were determined using two different temperature models (Oxley and Loewen-Shaw). The obtained constitutive equations were validated using dynamic tests and finite element simulation of high speed machining. The predictions obtained are also compared to those performed with the corresponding Johnson and Cook constitutive equations (JCE) from the literature. The sensitivity analysis revealed that the selected temperature models used in the analytical inverse method can affect significantly the identified material constants and thereafter predicted dynamic response and machining data. Moreover, the MCE obtained using the hybrid method performed better than the JCE obtained by only dynamic tests.
NASA Astrophysics Data System (ADS)
Tang, D. W.; Wang, C. Y.; Hu, Y. N.; Song, Y. X.
2010-03-01
In this present work, dynamic tests have been performed on hardened SKD11 steel (62 Rockwell C hardness) specimens by means of a high temperature split Hopkinson pressure bar (SHPB) test system. Effects of temperature as well as those of strain and strain rate for the hardened steel are taken into account by using two ellipsoidal radiant heating reflectors with two halogen lamps and magnetic valve. The result obtained at high stain rates were compared with those at low strain rates under the different temperature. It was seen that the flow stress curves are found to include a work hardening region and a work softening region and the mechanical behavior of the hardened steel is highly sensitive to both the strain rate and the temperature. To determine the true flow stress- true strain, temperature relationship, specimens are tested from room temperature to 1073K at a strain rate form 0.01 s-1 to 104 s-1: The parameters for a Johnson-Cook constitutive equation and a modified Johnson-Cook constitutive equation are determined from the test results by fitting the data from both quasi-static compression and high temperature-dynamic compression tests. The modified Johnson-Cook constitutive equation is more suitable for expressing the dynamic behavior of the hardened SKD11 steel above the vicinity of the recrystallization temperature.
NASA Astrophysics Data System (ADS)
Tang, D. W.; Wang, C. Y.; Hu, Y. N.; Song, Y. X.
2009-12-01
In this present work, dynamic tests have been performed on hardened SKD11 steel (62 Rockwell C hardness) specimens by means of a high temperature split Hopkinson pressure bar (SHPB) test system. Effects of temperature as well as those of strain and strain rate for the hardened steel are taken into account by using two ellipsoidal radiant heating reflectors with two halogen lamps and magnetic valve. The result obtained at high stain rates were compared with those at low strain rates under the different temperature. It was seen that the flow stress curves are found to include a work hardening region and a work softening region and the mechanical behavior of the hardened steel is highly sensitive to both the strain rate and the temperature. To determine the true flow stress- true strain, temperature relationship, specimens are tested from room temperature to 1073K at a strain rate form 0.01 s-1 to 104 s-1: The parameters for a Johnson-Cook constitutive equation and a modified Johnson-Cook constitutive equation are determined from the test results by fitting the data from both quasi-static compression and high temperature-dynamic compression tests. The modified Johnson-Cook constitutive equation is more suitable for expressing the dynamic behavior of the hardened SKD11 steel above the vicinity of the recrystallization temperature.
Bjerklie, D.M.; Dingman, S.L.; Bolster, C.H.
2005-01-01
[1] A set of conceptually derived in-bank river discharge-estimating equations (models), based on the Manning and Chezy equations, are calibrated and validated using a database of 1037 discharge measurements in 103 rivers in the United States and New Zealand. The models are compared to a multiple regression model derived from the same data. The comparison demonstrates that in natural rivers, using an exponent on the slope variable of 0.33 rather than the traditional value of 0.5 reduces the variance associated with estimating flow resistance. Mean model uncertainty, assuming a constant value for the conductance coefficient, is less than 5% for a large number of estimates, and 67% of the estimates would be accurate within 50%. The models have potential application where site-specific flow resistance information is not available and can be the basis for (1) a general approach to estimating discharge from remotely sensed hydraulic data, (2) comparison to slope-area discharge estimates, and (3) large-scale river modeling. Copyright 2005 by the American Geophysical Union.
Ding, Xiao-Rong; Zhang, Yuan-Ting
2015-01-01
The most commonly used method for cuffless blood pressure (BP) measurement is using pulse transit time (PTT), which is based on Moens-Korteweg (M-K) equation underlying the assumption that arterial geometries such as the arterial diameter keep unchanged. However, the arterial diameter is dynamic which varies over the cardiac cycle, and it is regulated through the contraction or relaxation of the vascular smooth muscle innervated primarily by the sympathetic nervous system. This may be one of the main reasons that impair the BP estimation accuracy. In this paper, we propose a novel indicator, the photoplethysmogram (PPG) intensity ratio (PIR), to evaluate the arterial diameter change. The deep breathing (DB) maneuver and Valsalva maneuver (VM) were performed on five healthy subjects for assessing parasympathetic and sympathetic nervous activities, respectively. Heart rate (HR), PTT, PIR and BP were measured from the simultaneously recorded electrocardiogram (ECG), PPG, and continuous BP. It was found that PIR increased significantly from inspiration to expiration during DB, whilst BP dipped correspondingly. Nevertheless, PIR changed positively with BP during VM. In addition, the spectral analysis revealed that the dominant frequency component of PIR, HR and SBP, shifted significantly from high frequency (HF) to low frequency (LF), but not obvious in that of PTT. These results demonstrated that PIR can be potentially used to evaluate the smooth muscle tone which modulates arterial BP in the LF range. The PTT-based BP measurement that take into account the PIR could therefore improve its estimation accuracy. PMID:26736283
Warner, James E.; Diaz, Manuel I.; Aquino, Wilkins; Bonnet, Marc
2014-01-01
This work focuses on the identification of heterogeneous linear elastic moduli in the context of frequency-domain, coupled acoustic-structure interaction (ASI), using either solid displacement or fluid pressure measurement data. The approach postulates the inverse problem as an optimization problem where the solution is obtained by minimizing a modified error in constitutive equation (MECE) functional. The latter measures the discrepancy in the constitutive equations that connect kinematically admissible strains and dynamically admissible stresses, while incorporating the measurement data as additional quadratic error terms. We demonstrate two strategies for selecting the MECE weighting coefficient to produce regularized solutions to the ill-posed identification problem: 1) the discrepancy principle of Morozov, and 2) an error-balance approach that selects the weight parameter as the minimizer of another functional involving the ECE and the data misfit. Numerical results demonstrate that the proposed methodology can successfully recover elastic parameters in 2D and 3D ASI systems from response measurements taken in either the solid or fluid subdomains. Furthermore, both regularization strategies are shown to produce accurate reconstructions when the measurement data is polluted with noise. The discrepancy principle is shown to produce nearly optimal solutions, while the error-balance approach, although not optimal, remains effective and does not need a priori information on the noise level. PMID:25339790
NASA Astrophysics Data System (ADS)
Warner, James E.; Diaz, Manuel I.; Aquino, Wilkins; Bonnet, Marc
2014-09-01
This work focuses on the identification of heterogeneous linear elastic moduli in the context of frequency-domain, coupled acoustic-structure interaction (ASI), using either solid displacement or fluid pressure measurement data. The approach postulates the inverse problem as an optimization problem where the solution is obtained by minimizing a modified error in constitutive equation (MECE) functional. The latter measures the discrepancy in the constitutive equations that connect kinematically admissible strains and dynamically admissible stresses, while incorporating the measurement data as additional quadratic error terms. We demonstrate two strategies for selecting the MECE weighting coefficient to produce regularized solutions to the ill-posed identification problem: 1) the discrepancy principle of Morozov, and 2) an error-balance approach that selects the weight parameter as the minimizer of another functional involving the ECE and the data misfit. Numerical results demonstrate that the proposed methodology can successfully recover elastic parameters in 2D and 3D ASI systems from response measurements taken in either the solid or fluid subdomains. Furthermore, both regularization strategies are shown to produce accurate reconstructions when the measurement data is polluted with noise. The discrepancy principle is shown to produce nearly optimal solutions, while the error-balance approach, although not optimal, remains effective and does not need a priori information on the noise level.
NASA Astrophysics Data System (ADS)
Haghi, M.; Anand, L.
1990-01-01
An experimental study of the constitutive response of the oxide dispersion-strengthened (ODS) superalloy MA 956, which consists of an Fe-Cr-Al matrix dispersion strengthened with yttria, has been performed. Single-crystal specimens of MA 956 having remarkably simple initial microstructures have been tested in compression in the temperature range of 900 °C to 1200 °C and in the axial strain-rate range of 1.8 x 10-4 s-1 to 10-2 s-1. The deformation response of the material has been examined by performing constant true strain-rate tests, strain-rate jump tests, and stress relaxation tests. The orientation dependence of the stress-strain response of the single crystals has been compensated for by determining the operative slip systems and resolving the stresses and strains accordingly. These experiments, together with electron-microscopic observations of deformed and quenched specimens, allow a number of conclusions to be drawn about the physics of particle strengthening in this simple ODS alloy at high temperatures. Further, drawing on this physical understanding, a set of phenomenological internal variable constitutive equations which model the high-temperature deformation behavior of this alloy is also developed. These equations reasonably well model not only the temperature and strain-rate sensitivity of the flow stress but also the strain-hardening behavior of the material.
Constitutive equations of a ballistic steel alloy as a function of temperature
NASA Astrophysics Data System (ADS)
Berkovic, L.; Chabotier, A.; Coghe, F.; Rabet, L.
2012-08-01
In the present work, dynamic tests have been performed on a new ballistic steel alloy by means of split Hopkinson pressure bars (SHPB). The impact behavior was investigated for strain rates ranging from 1000 to 2500 s-1, and temperatures in the range from - 196 to 300∘C. A robotized sample device was developed for transferring the sample from the heating or cooling device to the position between the bars. Simulations of the temperature evolution and its distribution in the specimen were performed using the finite element method. Measurements with thermocouples added inside the sample were carried out in order to validate the FEM simulations. The results show that a thermal gradient is present inside the sample; the average temperature loss during the manipulation of the sample is evaluated. In a last stage, optimal material constants for different constitutive models (Johnson-Cook, Zerilli-Amstrong, Cowper-Symonds) has been computed by fitting, in a least square sense, the numerical and experimental stress-strain curves. They have been implemented in a hydrocode for validation using a simple impact problem: an adapted projectile geometry with a truncated nose (.50 calibre fragment simulating projectiles) was fired directly against an armor plate. The parameters of the selected strength and failure models were determined. There is a good correspondence between the experimental and computed results. Nevertheless, an improved failure model is necessary to get satisfactory computed residual projectile velocities.
Identification of constitutive equation in hierarchical multiscale modelling of cup drawing process
NASA Astrophysics Data System (ADS)
Gawad, J.; Van Bael, A.; Eyckens, P.; Samaey, G.; Van Houtte, P.; Roose, D.
2011-08-01
In this paper we discuss extensions to a hierarchical multi-scale model (HMS) of cold sheet forming processes. The HMS model is capable of predicting changes in plastic anisotropy due to the evolution of crystallographic textures. The ALAMEL polycrystal plasticity model is employed to predict the texture evolution during the plastic deformation. The same model acts as a multilevel model and provides "virtual experiments" for calibration of an analytical constitutive law. Plastic anisotropy is described by means of the Facet method, which is able to reproduce the plastic potential in the entire strain rate space. The paper presents new strategies for identification of the Facet expression that are focused on improving its accuracy in the parts of the plastic potential surface that are more extensively used by the macroscopic FE model and therefore need to be reproduced more accurately. In this work we also evaluate the applicability of identification methods that (1) rely exclusively on the plastic potential or (2) can take into consideration also the deviatioric stresses derived from the Facet expression. It is shown that both methods provide the Facet expressions that correctly approximate the plastic anisotropy predicted by the multilevel ALAMEL model.
Ning, Xinguo; Zhu, Qiliang; Lanir, Yoram; Margulies, Susan S
2006-12-01
The objective of this study was to define the constitutive response of brainstem undergoing finite shear deformation. Brainstem was characterized as a transversely isotropic viscoelastic material and the material model was formulated for numerical implementation. Model parameters were fit to shear data obtained in porcine brainstem specimens undergoing finite shear deformation in three directions: parallel, perpendicular, and cross sectional to axonal fiber orientation and determined using a combined approach of finite element analysis (FEA) and a genetic algorithm (GA) optimizing method. The average initial shear modulus of brainstem matrix of 4-week old pigs was 12.7 Pa, and therefore the brainstem offers little resistance to large shear deformations in the parallel or perpendicular directions, due to the dominant contribution of the matrix in these directions. The fiber reinforcement stiffness was 121.2 Pa, indicating that brainstem is anisotropic and that axonal fibers have an important role in the cross-sectional direction. The first two leading relative shear relaxation moduli were 0.8973 and 0.0741, respectively, with corresponding characteristic times of 0.0047 and 1.4538 s, respectively, implying rapid relaxation of shear stresses. The developed material model and parameter estimation technique are likely to find broad applications in neural and orthopaedic tissues. PMID:17154695
NASA Astrophysics Data System (ADS)
Tutyshkin, Nikolai D.; Lofink, Paul; Müller, Wolfgang H.; Wille, Ralf; Stahn, Oliver
2016-09-01
On the basis of the physical concepts of void formation, nucleation, and growth, generalized constitutive equations are formulated for a tensorial model of plastic damage in metals based on three invariants. The multiplicative decomposition of the metric transformation tensor and a thermodynamically consistent formulation of constitutive relations leads to a symmetric second-order damage tensor with a clear physical meaning. Its first invariant determines the damage related to plastic dilatation of the material due to growth of the voids. The second invariant of the deviatoric damage tensor is related to the change in void shape. The third invariant of the deviatoric tensor describes the impact of the stress state on damage (Lode angle), including the effect of rotating the principal axes of the stress tensor (Lode angle change). The introduction of three measures with related physical meaning allows for the description of kinetic processes of strain-induced damage with an equivalent parameter in a three-dimensional vector space, including the critical condition of ductile failure. Calculations were performed by using experimentally determined material functions for plastic dilatation and deviatoric strain at the mesoscale, as well as three-dimensional graphs for plastic damage of steel DC01. The constitutive parameter was determined from tests in tension, compression, and shear by using scanning electron microscopy, which allowed to vary the Lode angle over the full range of its values [InlineEquation not available: see fulltext.]. In order to construct the three-dimensional plastic damage curve for a range of triaxiality parameters -1 ≤ ST ≤ 1 and of Lode angles [InlineEquation not available: see fulltext.], we used our own, as well as systematized published experimental data. A comparison of calculations shows a significant effect of the third invariant (Lode angle) on equivalent damage. The measure of plastic damage, based on three invariants, can be useful
NASA Astrophysics Data System (ADS)
Drugan, W. J.; Willis, J. R.
2016-06-01
A variational formulation employing the minimum potential and complementary energy principles is used to derive a micromechanics-based nonlocal constitutive equation for random linear elastic composite materials, relating ensemble averages of stress and strain in the most general situation when mean fields vary spatially. All information contained in the energy principles is retained; we employ stress polarization trial fields utilizing one-point statistics so that the resulting nonlocal constitutive equation incorporates up through three-point statistics. The variational structure is developed first for arbitrary heterogeneous linear elastic materials, then for randomly inhomogeneous materials, then for general n-phase composite materials, and finally for two-phase composite materials, in which case explicit variational upper and lower bounds on the nonlocal effective modulus tensor operator are derived. For statistically uniform infinite-body composites, these bounds are determined even more explicitly in Fourier transform space. We evaluate these in detail in an example case: longitudinal shear of an aligned fiber or void composite. We determine the full permissible ranges of the terms involving two- and three-point statistics in these bounds, and thereby exhibit explicit results that encompass arbitrary isotropic in-plane phase distributions; we also develop a nonlocal "Milton parameter", the variation of whose eigenvalues throughout the interval [0, 1] describes the full permissible range of the three-point term. Example plots of the new bounds show them to provide substantial improvement over the (two-point) Hashin-Shtrikman bounds on the nonlocal operator tensor, for all permissible values of the two- and three-point parameters. We next discuss further applications of the general nonlocal operator bounds: to any three-dimensional scalar transport problem e.g. conductivity, for which explicit results are given encompassing the full permissible ranges of the
NASA Astrophysics Data System (ADS)
Pang, L.; Liu, G. C.; Lu, J. P.
2015-12-01
The 20Cr2Ni4 alloy steel has the properties of high strength, toughness and hardness. It is used in large cross-section carburized parts, such as gears, shafts and components which are required high strength and good toughness. In order to study the static mechanical properties and dynamic mechanical properties of 20Cr2Ni4 steel, the static compression experiment and the Hopkinson Pressure Bar test are conducted. The stress-strain relationship within the scope of 25∼400°C is obtained by experiments, and softening effect of strain rate and strengthening effect of temperature is comprehensively analyzed. The paper has a more comprehensive understanding on mechanical response of 20Cr2Ni4 steel within the scope of 25∼400°C. Based on the experiment data the parameters in Johnson-Cook constitutive equation of 20Cr2Ni4 have been gotten. The research results of this paper lay a foundation for the further applications of 20Cr2Ni4 steel.
NASA Astrophysics Data System (ADS)
Yang, Jian; Boude, Serge; Giraud, Eliane; Dal Santo, Philippe
2013-05-01
Superplasticity is a characteristic of certain materials, in particular aluminium alloys, whereby very large deformations (up to 1000 %) can be obtained before fracture under certain conditions. Superplastic forming is therefore the process of deforming a flange under these conditions by applying a variable pressure. The final geometry is obtained when the flange takes the form of a die. In order to deform a material superplastically, the temperature of the material should be approximately a half of the absolute melting point of the material and the strain rate (or flow stress) should remain within a certain range. The most important issues concerning the industrial process are the prediction of the final thickness distribution and the computation of the optimal pressure law to maintain superplastic conditions. Finite element simulations make these predictions possible for industrial components. To ensure the precision of the simulations, it is important to have good knowledge of the material behaviour in the superplastic domain: rheological parameters, grain size, damage law, etc. This paper presents an experimental analysis of the superplastic behaviour of a 7xxx aluminium alloy used for aeronautic applications. The parameters of the constitutive equations (including damage) are identified by using tensile tests, spherical bulging tests and numerical simulations [1, 2]. The performance of the proposed laws [1, 3, and 4] is tested using axisymmetrical geometries with complex shapes by the comparison of numerical simulations and bulge tests.
Flow Behavior and Constitutive Equation of Ti-6.5Al-2Sn-4Zr-4Mo-1W-0.2Si Titanium Alloy
NASA Astrophysics Data System (ADS)
Yang, Xuemei; Guo, Hongzhen; Liang, Houquan; Yao, Zekun; Yuan, Shichong
2016-04-01
In order to get a reliable constitutive equation for the finite element simulation, flow behavior of Ti-6.5Al-2Sn-4Zr-4Mo-1W-0.2Si alloy under high temperature was investigated by carrying a series of isothermal compression tests at temperatures of 1153-1293 K and strain rates of 0.01-10.0 s-1 on the Gleeble-1500 simulator. Results showed that the true stress-strain curves exhibited peaks at small strains, after which the flow stress decreased monotonically. Ultimately, the flow curves reached steady state at the strain of 0.6, showing a dynamic flow softening phenomenon. The effects of strain rate, temperature, and strain on the flow behavior were researched by establishing a constitutive equation. The relations among stress exponent, deformation activation energy, and strain were preliminarily discussed by using strain rate sensitivity exponent and dynamic recrystallization kinetics curve. Stress values predicted by the modified constitutive equation showed a good agreement with the experimental ones. The correlation coefficient ( R) and average absolute relative error (AARE) were 98.2% and 4.88%, respectively, which confirmed that the modified constitutive equation could give an accurate estimation of the flow stress for BT25y titanium alloy.
Hoover, Wm G; Hoover, Carol G
2010-04-01
Guided by molecular dynamics simulations, we generalize the Navier-Stokes-Fourier constitutive equations and the continuum motion equations to include both transverse and longitudinal temperatures. To do so we partition the contributions of the heat transfer, the work done, and the heat flux vector between the longitudinal and transverse temperatures. With shockwave boundary conditions time-dependent solutions of these equations converge to give stationary shockwave profiles. The profiles include anisotropic temperature and can be fitted to molecular dynamics results, demonstrating the utility and simplicity of a two-temperature description of far-from-equilibrium states.
NASA Astrophysics Data System (ADS)
Motoyama, Yuichi; Shiga, Hidetoshi; Sato, Takeshi; Kambe, Hiroshi; Yoshida, Makoto
2016-11-01
Accurate simulation of residual stress and deformation is necessary to optimize the design and lifetime of casting components. Therefore, the recovery and strain-rate dependence of the stress-strain curve have been incorporated into empirical constitutive equations to improve the thermal stress analysis accuracy. Nevertheless, these equations present several difficulties related to the determination of material constants and their physical bases. This study suggested an empirical elasto-plastic-creep constitutive equation incorporating these phenomena. To determine the material parameters used in this constitutive equation, this study investigated tensile test methods to obtain stress-strain curves that most closely resemble those during or immediately after casting for the Al-Si-Cu high-pressure die-casting alloy JIS ADC 12 (A383.0), which exhibits natural aging. Results show that solution heat treatment with subsequent cooling to the test temperature should be applied to obtain stress-strain curves used for the thermal stress analysis of high-pressure die casting process of this alloy. The yield stresses obtained using the conventional heating method were 50-64 pct higher than those of the method described above. Therefore, the conventional method is expected to overestimate the overestimation of the predicted residual stress in die castings. Evaluation of the developed equation revealed that it can represent alloy recovery and strain-rate dependence.
NASA Astrophysics Data System (ADS)
Motoyama, Yuichi; Shiga, Hidetoshi; Sato, Takeshi; Kambe, Hiroshi; Yoshida, Makoto
2016-08-01
Accurate simulation of residual stress and deformation is necessary to optimize the design and lifetime of casting components. Therefore, the recovery and strain-rate dependence of the stress-strain curve have been incorporated into empirical constitutive equations to improve the thermal stress analysis accuracy. Nevertheless, these equations present several difficulties related to the determination of material constants and their physical bases. This study suggested an empirical elasto-plastic-creep constitutive equation incorporating these phenomena. To determine the material parameters used in this constitutive equation, this study investigated tensile test methods to obtain stress-strain curves that most closely resemble those during or immediately after casting for the Al-Si-Cu high-pressure die-casting alloy JIS ADC 12 (A383.0), which exhibits natural aging. Results show that solution heat treatment with subsequent cooling to the test temperature should be applied to obtain stress-strain curves used for the thermal stress analysis of high-pressure die casting process of this alloy. The yield stresses obtained using the conventional heating method were 50-64 pct higher than those of the method described above. Therefore, the conventional method is expected to overestimate the overestimation of the predicted residual stress in die castings. Evaluation of the developed equation revealed that it can represent alloy recovery and strain-rate dependence.
Model and simulation for melt flow in micro-injection molding based on the PTT model
NASA Astrophysics Data System (ADS)
Cao, Wei; Kong, Lingchao; Li, Qian; Ying, Jin; Shen, Changyu
2011-12-01
Unsteady viscoelastic flows were studied using the finite element method in this work. The Phan-Thien-Tanner (PTT) model was used to represent the rheological behavior of viscoelastic fluids. To effectively describe the microscale effects, the slip boundary condition and surface tension were added to the mathematical model for melt flow in micro-injection molding. The new variational equation of pressure, including the viscoelastic parameters and slip boundary condition, was generalized using integration by parts. A computer code based on the finite element method and finite difference method was developed to solve the melt flow problem. Numerical simulation revealed that the melt viscoelasticity plays an important role in the prediction of melt pressure, temperature at the gate and the succeeding melt front advancement in the cavity. Using the viscoelastic model one can also control the rapid increase in simulated pressure, temperature, and reduce the filling difference among different cavities. The short shot experiments of micro-motor shaft showed that the predicted melt front from the viscoelastic model is in fair agreement with the corresponding experimental results.
De Focatiis, Davide S. A.; Buckley, C. Paul; Embery, John
2008-07-07
This paper investigates the behaviour of a well-characterised monodisperse grade of entangled atactic polystyrene across a very wide temperature and strain rate range through linear and non-linear melt rheology and solid-state deformation. In an effort to construct a constitutive model for large deformations able to describe rheological response right across this wide timescale, two well-established rheological models are combined: the well known RoliePoly (RP) conformational melt model and the Oxford glass-rubber constitutive model for glassy polymers. Comparisons between experimental data and simulations from a numerical implementation of the model illustrate that the model can cope well with the range of deformations in which orientation is limited to length-scales longer than an entanglement length. One approach in which the model can be expanded to incorporate the effects of orientation on shorter length scales using anisotropic viscoplastic flow is briefly discussed.
NASA Astrophysics Data System (ADS)
Rieiro, I.; Gutiérrez, V.; Castellanos, J.; Carsí, M.; Larrea, M. T.; Ruano, O. A.
2010-09-01
A new strain-dependent equation derived from that of Garofalo is developed in this work. This equation describes mathematically the deformation behavior of materials as a function of strain, strain rate, and temperature and is valid over a wide range of strain with good statistical accuracy. An explicit expression σ left( \\varepsilon right) = fleft( {\\varepsilon ,T,dot{\\varepsilon }} right) is introduced that reproduces stress-strain curves. Statistical tools for determining the validity of the equation have been applied. Predictions from this expression were compared with torsion data obtained in AZ31 magnesium alloy that was deformed at various temperatures and strain rates. Analysis of the strain dependence of the Garofalo parameters allowed us to establish a steady state at strains of about 0.6. It also allows drawing conclusions about the microstructural changes that occur during deformation of the alloy. In addition, the characteristic points in the evolution with strain of the parameters of the equation are related to the most significant values that characterize the microstructural processes occurring during deformation of the AZ31 alloy. The observed decrease of Q and n as a function of strain is attributed first to a softening process due to dynamic recrystallization and grain size refinement and finally to flow localization. The predicted values obtained with the new constitutive equation and the experimental values for the AZ31 alloy are in good agreement with an average relative error of about 6.5 pct.
Continuous measurement of systolic blood pressure using the PTT and other parameters.
Park, E; Cho, B; Park, S; Lee, J; Lee, J; Kim, I; Kim, Sun
2005-01-01
In this paper, we proposed the regression model which could estimate unspecified people's systolic blood pressure (SBP) conveniently and continuously and checked its accuracy through clinical experiments. The method for estimating each individual SBP by using only pulse transit time (PTT) has been studied, but it is difficult to estimate unspecified people's SBP with the method using only PTT. Thus we researched several physical characteristic parameters which might affect blood pressure (BP) with the standard that we can measure them easily and conveniently, chose valid physical characteristic parameters through a clinical testing and correlation analysis, and made the regression model using PTT and valid physical characteristic parameters for estimating unspecified people's SBP. Comparing the result of the proposed method with American National Standards Institute of the Association of the Advancement of Medical Instrument (ANSI/AAMI), we know that the proposed regression model gives an acceptable result. PMID:17280992
NASA Astrophysics Data System (ADS)
Tomé, M. F.; Bertoco, J.; Oishi, C. M.; Araujo, M. S. B.; Cruz, D.; Pinho, F. T.; Vynnycky, M.
2016-04-01
This work is concerned with the numerical solution of the K-BKZ integral constitutive equation for two-dimensional time-dependent free surface flows. The numerical method proposed herein is a finite difference technique for simulating flows possessing moving surfaces that can interact with solid walls. The main characteristics of the methodology employed are: the momentum and mass conservation equations are solved by an implicit method; the pressure boundary condition on the free surface is implicitly coupled with the Poisson equation for obtaining the pressure field from mass conservation; a novel scheme for defining the past times t‧ is employed; the Finger tensor is calculated by the deformation fields method and is advanced in time by a second-order Runge-Kutta method. This new technique is verified by solving shear and uniaxial elongational flows. Furthermore, an analytic solution for fully developed channel flow is obtained that is employed in the verification and assessment of convergence with mesh refinement of the numerical solution. For free surface flows, the assessment of convergence with mesh refinement relies on a jet impinging on a rigid surface and a comparison of the simulation of a extrudate swell problem studied by Mitsoulis (2010) [44] was performed. Finally, the new code is used to investigate in detail the jet buckling phenomenon of K-BKZ fluids.
NASA Astrophysics Data System (ADS)
Wang, Fuzeng; Zhao, Jun; Zhu, Ningbo
2016-09-01
The flow behavior of Ti-6Al-4V alloy was studied by automated ball indentation (ABI) tests in a wide range of temperatures (293, 493, 693, and 873 K) and strain rates (10-6, 10-5, and 10-4 s-1). Based on the experimental true stress-plastic strain data derived from the ABI tests, the Johnson-Cook (JC), Khan-Huang-Liang (KHL) and modified Zerilli-Armstrong (ZA) constitutive models, as well as artificial neural network (ANN) methods, were employed to predict the flow behavior of Ti-6Al-4V. A comparative study was made on the reliability of the four models, and their predictability was evaluated in terms of correlation coefficient (R) and mean absolute percentage error. It is found that the flow stresses of Ti-6Al-4V alloy are more sensitive to temperature than strain rate under current experimental conditions. The predicted flow stresses obtained from JC model and KHL model show much better agreement with the experimental results than modified ZA model. Moreover, the ANN model is much more efficient and shows a higher accuracy in predicting the flow behavior of Ti-6Al-4V alloy than the constitutive equations.
Evolution, three-dimensional model and localization of truncated hemoglobin PttTrHb of hybrid aspen.
Dumont, Estelle; Jokipii-Lukkari, Soile; Parkash, Vimal; Vuosku, Jaana; Sundström, Robin; Nymalm, Yvonne; Sutela, Suvi; Taskinen, Katariina; Kallio, Pauli T; Salminen, Tiina A; Häggman, Hely
2014-01-01
Thus far, research on plant hemoglobins (Hbs) has mainly concentrated on symbiotic and non-symbiotic Hbs, and information on truncated Hbs (TrHbs) is scarce. The aim of this study was to examine the origin, structure and localization of the truncated Hb (PttTrHb) of hybrid aspen (Populus tremula L. × tremuloides Michx.), the model system of tree biology. Additionally, we studied the PttTrHb expression in relation to non-symbiotic class1 Hb gene (PttHb1) using RNAi-silenced hybrid aspen lines. Both the phylogenetic analysis and the three-dimensional (3D) model of PttTrHb supported the view that plant TrHbs evolved vertically from a bacterial TrHb. The 3D model suggested that PttTrHb adopts a 2-on-2 sandwich of α-helices and has a Bacillus subtilis -like ligand-binding pocket in which E11Gln and B10Tyr form hydrogen bonds to a ligand. However, due to differences in tunnel cavity and gate residue (E7Ala), it might not show similar ligand-binding kinetics as in Bs-HbO (E7Thr). The immunolocalization showed that PttTrHb protein was present in roots, stems as well as leaves of in vitro -grown hybrid aspens. In mature organs, PttTrHb was predominantly found in the vascular bundles and specifically at the site of lateral root formation, overlapping consistently with areas of nitric oxide (NO) production in plants. Furthermore, the NO donor sodium nitroprusside treatment increased the amount of PttTrHb in stems. The observed PttTrHb localization suggests that PttTrHb plays a role in the NO metabolism.
NASA Astrophysics Data System (ADS)
Sui, Dashan; Wang, Tao; Zhu, Lingling; Gao, Liang; Cui, Zhenshan
2016-08-01
The hot deformation behavior and hot workability characteristics of as-cast SA508-3 steel were studied by modeling the constitutive equations and developing hot processing maps. The isothermal compression experiments were carried out at temperatures of 950°C, 1050°C, 1150°C, and 1250°C and strain rates of 0.001 s-1, 0.01 s-1, 0.1 s-1, and 1 s-1 respectively. The two-stage flow stress models were established through the classical theories on work hardening and softening, and the solution of activation energy for hot deformation was 355.0 kJ mol-1 K-1. Based on the dynamic material model, the power dissipation and instability maps were developed separately at strains of 0.2, 0.4, 0.6 and 0.8. The power dissipation rate increases with both the increase of temperature and the decrease of strain rate, and the instable region mainly appears on the conditions of low temperature and high strain rate. The optimal hot working parameters for as-cast SA508-3 steel are 1050-1200°C/0.001-0.1 s-1, with about 25-40% peak efficiency of power dissipation.
NASA Technical Reports Server (NTRS)
Hakkinen, S.
1984-01-01
This study is aimed at the modelling of mesoscale processed such as up/downwelling and ice edge eddies in the marginal ice zones. A 2-dimensional coupled ice-ocean model is used for the study. The ice model is coupled to the reduced gravity ocean model (f-plane) through interfacial stresses. The constitutive equations of the sea ice are formulated on the basis of the Reiner-Rivlin theory. The internal ice stresses are important only at high ice concentrations (90-100%), otherwise the ice motion is essentially free drift, where the air-ice stress is balanced by the ice-water stress. The model was tested by studying the upwelling dynamics. Winds parallel to the ice edge with the ice on the right produce upwilling because the air-ice momentum flux is much greater that air-ocean momentum flux, and thus the Ekman transport is bigger under the ice than in the open water. The upwelling simulation was extended to include temporally varying forcing, which was chosen to vary sinusoidally with a 4 day period. This forcing resembles successive cyclone passings. In the model with a thin oceanic upper layer, ice bands were formed.
PT, aPTT, TT and the hemostatic safety threshold of dabigatran and rivaroxaban.
Ibrahim, Firas; Calmette, Leyla; Layka, Ayham; Horellou, Marie-Hélène; Mazoyer, Élisabeth; Gouin-Thibault, Isabelle; Flaujac, Claire
2016-08-01
The proposals of the Working group on perioperative hemostasis (Groupe d'intérêt en hémostase péri-opératoire (GIHP)) concerning the perioperative management of patients receiving the direct oral anticoagulants (DOACs) are based on the measure of their anticoagulant activities (anti-Xa for rivaroxaban and anti-IIa for dabigatran) with a safety threshold ≤ 30 ng/mL. If the dosage of the drug is not available, proposals are based on the combination of a PT ≥80% and an aPTT ≤1.20. The aim of our study was to evaluate the performance of PT, aPTT and thrombin time to predict values above or below the safety threshold. The measurement of DOACs concentration was carried out in 64 samples from patients treated with rivaroxaban and 48 samples from patients treated with dabigatran. The PT and aPTT were measured for all samples, while the TT was measured only for patients receiving dabigatran. The absence of agreement between the global hemostasis tests and the DOACs concentrations was observed for 10% of patients receiving dabigatran and 27% of patients with rivaroxaban treatment. Apart from dabigatran for which the predictive negative value of PT and aPTT or TT allows to exclude a concentration >30 ng/mL in 100% of cases, our results highlight the risk of misinterpretation when using global coagulation tests (PT and aPPT) for determination of the safety threshold for patients receiving the DOACs. PMID:27492699
Byun, Jung-Hyun; Jang, In-Seok; Kim, Jong Woo
2016-01-01
Background Unfractionated heparin (UFH) has unstable pharmacokinetics and requires close monitoring. The activated partial thromboplastin time (aPTT) test has been used to monitor UFH therapy for decades in Korea, but its results can be affected by numerous variables. We established an aPTT heparin therapeutic range (HTR) corresponding to therapeutic anti-Xa levels for continuous intravenous UFH administration, and used appropriate monitoring to determine if an adequate dose of UFH was applied. Methods A total of 134 ex vivo samples were obtained from 71 patients with a variety of thromboembolisms. All patients received intravenous UFH therapy and were enrolled from June to September 2015 at Gyeongsang National University Hospital. All laboratory protocols were in accordance with the Clinical and Laboratory Standards Institute guidelines and the College of American Pathologist requirements for aPTT HTR. Results An aPTT range of 87.1 sec to 128.7 sec corresponded to anti-Xa levels of 0.3 IU/mL to 0.7 IU/mL for HTR under our laboratory conditions. Based on their anti-Xa levels, blood specimen distribution were as follows: less than 0.3 IU/mL, 65.7%; 0.3–0.7 IU/mL (therapeutic range), 33.6%; and more than 0.7 IU/mL, 0.7%. No evidence of recurring thromboembolism was observed. Conclusion Using the conventional aPTT target range may lead to inappropriate dosing of UFH. Transitioning from the aPTT test to the anti-Xa assay is required to avoid the laborious validation of the aPTT HTR test, even though the anti-Xa assay is more expensive. PMID:27722127
NASA Astrophysics Data System (ADS)
Ghamarian, Iman; Samimi, Peyman; Dixit, Vikas; Collins, Peter C.
2015-11-01
While it is useful to predict properties in metallic materials based upon the composition and microstructure, the complexity of real, multi-component, and multi-phase engineering alloys presents difficulties when attempting to determine constituent-based phenomenological equations. This paper applies an approach based upon the integration of three separate modeling approaches, specifically artificial neural networks, genetic algorithms, and Monte Carlo simulations to determine a mechanism-based equation for the yield strength of α+ β processed Ti-6Al-4V (all compositions in weight percent) which consists of a complex multi-phase microstructure with varying spatial and morphological distributions of the key microstructural features. Notably, this is an industrially important alloy yet an alloy for which such an equation does not exist in the published literature. The equation ultimately derived in this work not only can accurately describe the properties of the current dataset but also is consistent with the limited and dissociated information available in the literature regarding certain parameters such as intrinsic yield strength of pure hexagonal close-packed alpha titanium. In addition, this equation suggests new interesting opportunities for controlling yield strength by controlling the relative intrinsic strengths of the two phases through solid solution strengthening.
NASA Astrophysics Data System (ADS)
Duron-Dufrenne, M.
The degree to which a turtle would accept the Transat-type ARGOS PTT, and the reliability of the harness securing it to the carapace were tested, using an adult kept in a swimming pool for 36 hr. Its pelagic behavior turns out to be comparable to that in the open sea, the animal appearing unperturbed by the equipment.
NASA Astrophysics Data System (ADS)
Alexandrov, Sergei; Goldstein, Robert
2016-11-01
The main objective of the present paper is to compare, by means of a problem permitting a closed-form solution, qualitative behavior of solutions based on three models of strain hardening plasticity and two models of viscoplasticity. The elastic portion of the strain tensor is neglected. The study focuses on the solution behavior near frictional interfaces. The solution behavior essentially depends on the model chosen. Such features of the solutions as nonexistence and singularity are emphasized. The key constitutive parameter that divides all the models considered into two groups is the saturation stress. In particular, under certain conditions no solution satisfying the regime of sticking exists for the models that involve the saturation stress. Qualitative comparison with numerous experimental observations is made. It is concluded that models with a saturation stress, including the models considered in the present paper, may be capable of describing the generation of a narrow layer of severe plastic deformation in the vicinity of frictional interfaces.
Isothermal and non-isothermal viscoelastic flow of PTT fluid in lid-driven polar cavity
NASA Astrophysics Data System (ADS)
Mercan, Hatice; Atalık, Kunt
2012-12-01
The isothermal and non-isothermal viscoelastic flow of Phan-Thien-Tanner (PTT) fluids is considered in liddriven polar cavity geometry, using a numerical solution method with parameter continuation technique. Thermoelastic effects, in terms of elastic/elongational effects and viscous dissipation, are demonstrated by the changes in vortical structure, temperature/stress distributions and heat transfer characteristics in the curved cavity. Central vortex/maximum temperature location shifts are observed under elastic and elongational (strain hardening and strain softening/shear thinning) effects for isothermal and non-isothermal conditions. The growth in size and strength of a secondary vortex is denoted in the downstream stationary corner of the cavity for the viscoelastic fluid under strain hardening, which also introduces an increase in stress gradients. Viscous heating is observed with elongational effects near the central vortex in the cavity. Stress components and their gradients decrease under viscous dissipation. The changes in temperature field and heat transfer properties in the cavity are revealed.
Random-matrix theory of amplifying and absorbing resonators with {PT} or {PTT}^{\\prime } symmetry
NASA Astrophysics Data System (ADS)
Birchall, Christopher; Schomerus, Henning
2012-11-01
We formulate Gaussian and circular random-matrix models representing a coupled system consisting of an absorbing and an amplifying resonator, which are mutually related by a generalized time-reversal symmetry. Motivated by optical realizations of such systems we consider a {PT} or a {PTT}^{\\prime } time-reversal symmetry, which impose different constraints on magneto-optical effects, and then focus on five common settings. For each of these, we determine the eigenvalue distribution in the complex plane in the short-wavelength limit, which reveals that the fraction of real eigenvalues among all eigenvalues in the spectrum vanishes if all classical scales are kept fixed. Numerically, we find that the transition from real to complex eigenvalues in the various ensembles display a different dependence on the coupling strength between the two resonators. These differences can be linked to the level spacing statistics in the Hermitian limit of the considered models. This article is part of a special issue of Journal of Physics A: Mathematical and Theoretical devoted to ‘Quantum physics with non-Hermitian operators’.
Reaction kinetics, P-T-t paths and rates of tectonic processes
Bohlen, S.R.; Hankins, W.B.; Eckert, J.O. Jr.; Kirby, S.H.; Liu, J. ); Hacker, B.R.; Mosenfelder, J.L. . Dept. of Geology)
1992-01-01
The interpretation of portions of P-T-time (t) paths in metamorphic rocks assumes that continuous and discontinuous reactions record local equilibrium as P-T conditions change, implying that the kinetics of many reactions are rapid relative to dT/dt and dP/dt. Occurrence of eclogite veins in granulites from Bergen, Norway as well as occurrences of coesite and diamond in crustal rocks imply that, under certain conditions, this assumption is wrong. Knowledge of the kinetics of important reactions under appropriate conditions would provide limits on the duration of relatively narrowly defined P-T conditions, allow inference of the rates of exhumation of rocks containing high-pressure phases, and allow the calculation of the time required for the conversion of gabbro to eclogite in the lower crust as a function of P-T-t. The authors are currently assessing the rates of key phase transformations: calcite to aragonite, albite to jadeite + quartz, coesite to quartz, opx[sub Fs[sup 80
Thomas, Owain; Lybeck, Emanuel; Strandberg, Karin; Tynngård, Nahreen; Schött, Ulf
2015-01-01
Background Low molecular weight heparins (LMWH’s) are used to prevent and treat thrombosis. Tests for monitoring LMWH’s include anti-factor Xa (anti-FXa), activated partial thromboplastin time (aPTT) and thrombin generation. Anti-FXa is the current gold standard despite LMWH’s varying affinities for FXa and thrombin. Aim To examine the effects of two different LMWH’s on the results of 4 different aPTT-tests, anti-FXa activity and thrombin generation and to assess the tests’ concordance. Method Enoxaparin and tinzaparin were added ex-vivo in concentrations of 0.0, 0.5, 1.0 and 1.5 anti-FXa international units (IU)/mL, to blood from 10 volunteers. aPTT was measured using two whole blood methods (Free oscillation rheometry (FOR) and Hemochron Jr (HCJ)) and an optical plasma method using two different reagents (ActinFSL and PTT-Automat). Anti-FXa activity was quantified using a chromogenic assay. Thrombin generation (Endogenous Thrombin Potential, ETP) was measured on a Ceveron Alpha instrument using the TGA RB and more tissue-factor rich TGA RC reagents. Results Methods’ mean aPTT at 1.0 IU/mL LMWH varied between 54s (SD 11) and 69s (SD 14) for enoxaparin and between 101s (SD 21) and 140s (SD 28) for tinzaparin. ActinFSL gave significantly shorter aPTT results. aPTT and anti-FXa generally correlated well. ETP as measured with the TGA RC reagent but not the TGA RB reagent showed an inverse exponential relationship to the concentration of LMWH. The HCJ-aPTT results had the weakest correlation to anti-FXa and thrombin generation (Rs0.62–0.87), whereas the other aPTT methods had similar correlation coefficients (Rs0.80–0.92). Conclusions aPTT displays a linear dose-respone to LMWH. There is variation between aPTT assays. Tinzaparin increases aPTT and decreases thrombin generation more than enoxaparin at any given level of anti-FXa activity, casting doubt on anti-FXa’s present gold standard status. Thrombin generation with tissue factor-rich activator is
P-T-t path for the Archean Pikwitonei Granulite Domain and Cross Lake Subprovince, Manitoba, Canada
NASA Technical Reports Server (NTRS)
Mezger, K.; Bohlen, S. R.; Hanson, G. N.
1988-01-01
The rationale was outlined for constructing pressure-temperature-time (P-T-t) paths by using U-Pb dating of garnet produced in thermobarometrically sensitive reactions. In an example from the Pikwitonei granulites of the Northwestern Superior Province of the Canadian Shield, garnets were formed at 2744-2742 Ma, 2700-2689 Ma, and 2605-2590 Ma, the latter events coinciding with times recorded by U-Pb zircon systems. Garnet grew during metamorphism at 6.5 kbar, 630 to 750 C and later at 7.2 to 7.5 kbar, 800 C; the later metamorphism apparently did not exceed the U-Pb closure temperature. The resultant P-T-t path is counterclockwise, with late isobaric cooling, interpreted to result from magmatic heating at an Andean margin.
Wang, Kaikai; Zhang, Yifan; Wang, Juan; Yuan, Ahu; Sun, Minjie; Wu, Jinhui; Hu, Yiqiao
2016-01-01
Combination of photothermal and photodynamic therapy (PTT/PDT) offer unique advantages over PDT alone. However, to achieve synergetic PDT/PTT effect, one generally needs two lasers with different wavelengths. Near-infrared dye IR-780 could be used as photosensitizer both for PTT and PDT, but its lipophilicity limits its practical use and in vivo efficiency. Herein, a simple multifunctional IR780-loaded nanoplatform based on transferrin was developed for targeted imaging and phototherapy of cancer compatible with a single-NIR-laser irradiation. The self-assembled transferrin-IR780 nanoparticles (Tf-IR780 NPs) exhibited narrow size distribution, good photo-stability, and encouraging photothermal performance with enhanced generation of ROS under laser irradiation. Following intravenous injection, Tf-IR780 NPs had a high tumor-to-background ratio in CT26 tumor-bearing mice. Treatment with Tf-IR780 NPs resulted in significant tumor suppression. Overall, the Tf-IR780 NPs show notable targeting and theranostic potential in cancer therapy. PMID:27263444
The high-affinity poplar ammonium importer PttAMT1.2 and its role in ectomycorrhizal symbiosis.
Selle, Anita; Willmann, Martin; Grunze, Nina; Gessler, Arthur; Weiss, Michael; Nehls, Uwe
2005-12-01
One way to elucidate whether ammonium could act as a nitrogen (N) source delivered by the fungus in ectomycorrhizal symbiosis is to investigate plant ammonium importers. Expression analysis of a high-affinity ammonium importer from Populus tremulax tremuloides (PttAMT1.2) and of known members of the AMT1 gene family from Populus trichocarpa was performed. In addition, PttAMT1.2 function was studied in detail by heterologous expression in yeast. PttAMT1.2 expression proved to be root-specific, affected by N nutrition, and strongly increased in a N-independent manner upon ectomycorrhiza formation. The corresponding protein had a K(M) value for ammonium of c. 52 microm. From the seven members of the AMT1 gene family, one gene was exclusively expressed in roots while four genes were detectable in all poplar organs but with varying degrees of expression. Ectomycorrhiza formation resulted in a strong upregulation of three of these genes. Our results indicate an increased ammonium uptake capacity of mycorrhized poplar roots and suggest, together with the expression of putative ammonium exporter genes in the ectomycorrhizal fungus Amanita muscaria, that ammonium could be a major N source delivered from the fungus towards the plant in symbiosis.
NASA Astrophysics Data System (ADS)
Navalekar, Abhijit C.; Michalson, William R.
Unintentional Denial of Service (DOS) problems occur in wireless networks such as Wi-Fi due to factors such as signal capture, interference and have been studied extensively in the literature. A similar problem manifests amongst nodes within a LMR network due to different PTT delay characteristics. We first present the typical PTT delay values and distributions followed by an analytical model to estimate the denial of service problem. The results obtained using the model and simulations show that the LMR nodes experience DOS due to collisions resulting from PTT delays. The results also show that there exists an asymmetry in the performance of individual nodes and the extent of this asymmetry is a function of total number of nodes in the system and the density of nodes with similar PTT delay profiles. These observations have implications in both performance and capacity planning of an adhoc LMR network.
NASA Astrophysics Data System (ADS)
Guillou-Frottier, L.; Burov, E.; Cloetingh, S.; Le Goff, E.; Deschamps, Y.; Huet, B.; Bouchot, V.
2012-06-01
Plume head-lithosphere interactions around cratonic blocks result in thermo-mechanical disturbances that lead to heating and burial phases of crustal rocks. We present results from numerical models of plume head-cratonic blocks interactions where a free upper surface condition and realistic rheologies are accounted for. These models include distinct cratonic blocks embedded within a continental lithosphere and separated by several hundreds of kilometers. Surface topography, thermal field and effective viscosity values are tracked for 20 Myr of interactions. The modeled dynamic interaction of a plume head around cratonic blocks results in two main types of instabilities, each of them resulting in a distinct P-T-t path. The "slab-like" instability, focused on cratonic edges when plume head is away from the craton center, shows a near-isothermal burial phase, while the "drip-like" instability occurring above plume head material results in a near-isobaric heating phase. Consequently, both clockwise and counterclockwise P-T-t paths can be expected around cratons, as actually observed around the Tanzanian craton and other cratonic areas. Metallogenic data from gemstone-bearing rocks in south-east Africa and data from ultrahigh temperature and ultrahigh pressure metamorphism are compatible with our model. It appears that vertical mantle dynamics around cratons may also explain thermobarometric signatures that are often attributed to horizontal tectonics.
Najafi, Atabak; Nikeish, Masoomeh; Etezadi, Farhad; Pourfakhr, Pejman; Imani, Farsad; Khajavi, Mohammad Reza; Shariat Moharari, Reza
2015-10-01
Heparin is frequently used in different clinical settings to reduce the coagulating ability of the blood. Because of probable adverse effects owing to heparin therapy and regarding variability of patients' responses to heparin, which make it very unreliable, it seems prudent to monitor meticulously its effects on the human body. There are a lot of laboratory tests to watch its effects on the body for example; aPTT and ROTEM are the most widely used tests that are performed today. We aimed to compare the aPTT test results against changes of CT parameter of the ROTEM test due to heparin administration. This study was conducted on 45 critically ill patients who needed to receive heparin according to their clinical status. All patients received 550 to 1500 unit heparin per hour (on average 17.5 unit heparin per kilogram weight). While the patients were under infusion of heparin, two blood samples (5 ml) were taken from a newly established cubital vein, just five hours after commencement of heparin therapy. One sample was used for aPTT and the other one for ROTEM. The correlation between aPTT and the changes of CT parameter of the ROTEM with heparin dosage and infusion was the primary outcome. The correlation between heparin therapy and the changes of other parameters like MCF, CFT, and a number of platelets were the secondary outcome of the study. The only significant correlation was between changes of CT and aPTT (P=0.000). The other variables were not correlated. Changes of CT parameter of ROTEM test can be used for monitoring of reduced coagulability during heparin infusion instead of aPTT test. PMID:26615378
Najafi, Atabak; Nikeish, Masoomeh; Etezadi, Farhad; Pourfakhr, Pejman; Imani, Farsad; Khajavi, Mohammad Reza; Shariat Moharari, Reza
2015-10-01
Heparin is frequently used in different clinical settings to reduce the coagulating ability of the blood. Because of probable adverse effects owing to heparin therapy and regarding variability of patients' responses to heparin, which make it very unreliable, it seems prudent to monitor meticulously its effects on the human body. There are a lot of laboratory tests to watch its effects on the body for example; aPTT and ROTEM are the most widely used tests that are performed today. We aimed to compare the aPTT test results against changes of CT parameter of the ROTEM test due to heparin administration. This study was conducted on 45 critically ill patients who needed to receive heparin according to their clinical status. All patients received 550 to 1500 unit heparin per hour (on average 17.5 unit heparin per kilogram weight). While the patients were under infusion of heparin, two blood samples (5 ml) were taken from a newly established cubital vein, just five hours after commencement of heparin therapy. One sample was used for aPTT and the other one for ROTEM. The correlation between aPTT and the changes of CT parameter of the ROTEM with heparin dosage and infusion was the primary outcome. The correlation between heparin therapy and the changes of other parameters like MCF, CFT, and a number of platelets were the secondary outcome of the study. The only significant correlation was between changes of CT and aPTT (P=0.000). The other variables were not correlated. Changes of CT parameter of ROTEM test can be used for monitoring of reduced coagulability during heparin infusion instead of aPTT test.
The Constitutional Amendment Process
ERIC Educational Resources Information Center
Chism, Kahlil
2005-01-01
This article discusses the constitutional amendment process. Although the process is not described in great detail, Article V of the United States Constitution allows for and provides instruction on amending the Constitution. While the amendment process currently consists of six steps, the Constitution is nevertheless quite difficult to change.…
NASA Astrophysics Data System (ADS)
Azizi, H.; Moinevaziri, H.; Mohajjel, M.; Yagobpoor, A.
2006-06-01
Metamorphic rocks in the Khoy region are exposed between obducted ophiolites to the southwest and sedimentary rocks of Precambrian-Paleozoic age to the northeast. The Qom formation (Oligocene-Miocene) with a basal conglomerate transgressively overlies all of these rocks. The metamorphic rocks consist of both metasediments and metabasites. The metasediments are micaschist, garnet-staurolite schist and garnet-staurolite sillimanite schist with some meta-arkose, marble and quartzite. The metabasites are metamorphosed to greenschist and amphibolite facies from a basaltic and gabbroic protolith of tholeiitic and calc-alkaline rocks. Geothermobarometry based on the equivalence of minerals stability and their paragenesis in these rocks and microprobe analyses by several different methods indicate that metamorphism occurred in a temperature range between 450 and 680 °C at 5.5 and 7.5 kb pressure. Rims of minerals reveal a considerable decrease of pressure (<2 kb) and insignificant decrease of temperature. The PTt path of this metamorphism is normal. The MFG line passes above the triple junction of Al 2SiO 5 polymorphs, and the average geothermal gradient during metamorphism was from 27 to 37 °C/km, which is more concordant with the temperature regime of collision zones. We infer that crustal thickening during post-Cretaceous (possibly Eocene) collision of the Arabian plate and the Azerbaijan-Albourz block was the main factor that caused the metamorphism in the studied area.
NASA Astrophysics Data System (ADS)
Glassley, W. E.; Korstgård, J.; Sorensen, K.
2015-12-01
Reconstructing tectonic histories relies on the ability to establish P-T-t paths from samples and data collected in the field. Efforts to establish detailed P-T-t pathways have benefitted recently from dramatically improved ability to resolve mineral chemical and isotopic properties at the micron scale. We present here a new interpretation of the HP and UHP metamorphic history of a 1.8 Gya terrain in West Greenland (Glassley et al., 2014) that is based on these new analytical capabilities, coupled with sampling at high spatial density. The terrain consists of a tectonic assemblage of metasomatically altered pillow basalts, ultramafic bodies, exhalative and chemical oceanic metasediments, pelites, and quartzo-feldspathic gneisses, that are the preserved remnants of a subduction channel. Using LA-SF-ICP-MS analyses on zircons, we time-correlated recrystallization events that could be well-documented using micro-analytical techniques (EBMA; Raman; LA-ICP-MS). More than 700 207Pb/206Pb dates and more than 1,000 electron microprobe mineral analyses were used in this correlation effort. The results demonstrate that: 1) Recrystallization is highly localized, often restricted to tectonic domains of less than a few 10s of km2. Few tectonic lenses preserve evidence of the most extreme P-T conditions (5 GPa at temperatures of approximately 1,000 C); 2) The extent of area involved in a recrystallization "event" is mainly a reflection of local rock chemistry/mineralogy and fluid activity; 3) Since individual crystals preserve multiple parts of a P-T-t path in compositional zoning, isotopic dates must be very carefully correlated with corresponding mineral compositions in order to establish t at P & T; 4) Preservation of the prograde P-T-t path during subduction is rare.
Poumpouridou, Nikoleta; Goutas, Nikolaos; Tsionou, Christina; Dimas, Kleanthi; Lianidou, Evi; Kroupis, Christos
2016-04-01
Beyond BRCA1 and BRCA2 genes, PALB2 (Partner and localizer of BRCA2) emerges as the third breast cancer susceptibility gene due to its role in the same DNA repair pathway: homologous recombination. In most populations studied so far, PALB2 mutations are detected in 1-2% of BRCA negative female patients. PALB2 gene contains 13 exons; exons 4 and 5 consist 65% of the coding area. We developed a protein truncation test (PTT) for quick screening of truncating pathogenic mutations of these two large exons. Specific primers were de novo, in silico designed and the PTT-PCR products were translated in the presence of biotinylated lysine and detected colorimetrically. The assay was initially tested in 30 patients with hereditary breast cancer, negative for BRCA mutations and then, in 17 patients with the rare medullary breast cancer subtype. Small PALB2 exons were screened with high-resolution melting curve analysis (HRMA) and the large DNA rearrangements with multiplex ligation-dependent probe amplification (MLPA). Any alterations detected were verified by Sanger DNA Sequencing. The developed PTT methodology is highly specific for clinical significant mutations; positive control samples that produce truncated PALB2 peptides were correctly identified and the method was accurate when compared to DNA sequencing. We did not detect any deleterious PALB2 mutation in both groups of patients. HRMA and MLPA were also negative for all tested samples. However, our novel, fast and cost-effective PTT method for pathogenic mutation detection of the two large PALB2 exons can be applied in screening of a large number of breast cancer patients. PMID:26573693
ERIC Educational Resources Information Center
Greenhut, Stephanie; Jones, Megan
2010-01-01
On their visit to the National Archives Experience in Washington, D.C., students in Jenni Ashley and Gay Brock's U.S. history classes at the Potomac School in McLean, Virginia, participated in a pilot program called "The Constitution by Cell." Armed with their cell phones, a basic understanding of the Constitution, and a willingness to participate…
Interpreting the Constitution.
ERIC Educational Resources Information Center
Brennan, William J., Jr.
1987-01-01
Discusses constitutional interpretations relating to capital punishment and protection of human dignity. Points out the document's effectiveness in creating a new society by adapting its principles to current problems and needs. Considers two views of the Constitution that lead to controversy over the legitimacy of judicial decisions. (PS)
ERIC Educational Resources Information Center
Weatherman, Donald V.
1987-01-01
Courses on the Constitution must focus on the principles of government. Those principles and how the understanding of those principles shaped the document are appropriate subjects for consideration. The best sources for an examination of the Constitution are "The Records of the Federal Convention of 1787" and "The Federalist." (MLW)
Constitutive modeling for isotropic materials
NASA Technical Reports Server (NTRS)
Lindholm, Ulric S.; Chan, Kwai S.
1986-01-01
The objective of the program is to evaluate and develop existing constitutive models for use in finite-element structural analysis of turbine engine hot section components. The class of constitutive equation studied is considered unified in that all inelastic deformation including plasticity, creep, and stress relaxation are treated in a single term rather than a classical separation of plasticity (time independent) and creep (time dependent) behavior. The unified theories employed also do not utilize the classical yield surface or plastic potential concept. The models are constructed from an appropriate flow law, a scalar kinetic relation between strain rate, temperature and stress, and evolutionary equations for internal variables describing strain or work hardening, both isotropic and directional (kinematic). This and other studies have shown that the unified approach is particularly suited for determining the cyclic behavior of superalloy type blade and vane materials and is entirely compatible with three-dimensional inelastic finite-element formulations. The behavior was examined of a second nickel-base alloy, MAR-M247, and compared it with the Bodner-Partom model, further examined procedures for determining the material-specific constants in the models, and exercised the MARC code for a turbine blade under simulated flight spectrum loading. Results are summarized.
Constitutive modeling for isotropic materials
NASA Technical Reports Server (NTRS)
Chan, K. S.; Lindholm, U. S.; Bodner, S. R.
1988-01-01
The third and fourth years of a 4-year research program, part of the NASA HOST Program, are described. The program goals were: (1) to develop and validate unified constitutive models for isotropic materials, and (2) to demonstrate their usefulness for structural analysis of hot section components of gas turbine engines. The unified models selected for development and evaluation were those of Bodner-Partom and of Walker. The unified approach for elastic-viscoplastic constitutive equations is a viable method for representing and predicting material response characteristics in the range where strain rate and temperature dependent inelastic deformations are experienced. This conclusion is reached by extensive comparison of model calculations against the experimental results of a test program of two high temperature Ni-base alloys, B1900+Hf and Mar-M247, over a wide temperature range for a variety of deformation and thermal histories including uniaxial, multiaxial, and thermomechanical loading paths. The applicability of the Bodner-Partom and the Walker models for structural applications has been demonstrated by implementing these models into the MARC finite element code and by performing a number of analyses including thermomechanical histories on components of hot sections of gas turbine engines and benchmark notch tensile specimens. The results of the 4-year program have been published in four annual reports. The results of the base program are summarized in this report. The tasks covered include: (1) development of material test procedures, (2) thermal history effects, and (3) verification of the constitutive model for an alternative material.
ERIC Educational Resources Information Center
Journal of Dental Education, 1981
1981-01-01
Constitutions and bylaws of the American Association of Dental Schools are presented, covering organization name, statement of purpose, administrative organization, offices, membership, legislative and administrative bodies, elected and appointed officers, regular and special sessions, sections, publications, election, and finance. (MSE)
Tomita, Masaru; Itaya, Mitsuhiro
2015-01-01
Stepwise deletions in the only plasmid in Thermus thermophilus HB27, megaplasmid pTT27, showed that two distantly located loci were important for maintenance of the plasmid. One is a minimum replicon including one gene, repT, coding a replication initiator, and the other encodes subunits of class I ribonucleotide reductase (RNR) for deoxynucleoside triphosphate (dNTP) synthesis. Since the initiator protein, RepT, bound to direct repeats downstream from its own gene, it was speculated that a more-downstream A+T-rich region, which was critical for replication ability, could be unwound for replication initiation. On the other hand, the class I RNR is not necessarily essential for cell growth, as evidenced by the generation of the plasmid-free strain by the loss of pTT27. However, the plasmid-free strain culture has fewer viable cells than the wild-type culture, probably due to a dNTP pool imbalance in the cell. This is because of the introduction of the class I RNR genes or the supplementation of 5′-deoxyadenosylcobalamin, which stimulated class II RNR encoded in the chromosome, resolved the decrease in the number of viable cells in the plasmid-free strain. Likewise, these treatments dramatically enhanced the efficiency of transformation by exogenous plasmids and the stability of the plasmids in the strain. Therefore, the class I RNR would enable the stable maintenance of plasmids, including pTT27, as a result of genome replication normalized by reversing the dNTP pool imbalance. The generation of this plasmid-free strain with great natural competence and its analysis in regard to exogenous plasmid maintenance will expand the availability of HB27 for thermophilic cell factories. PMID:26712540
1987-01-01
This document reprints major provisions of the 1982 Constitution of Equatorial Guinea. The Constitution calls for protection of the family as the basic building block of society. Foreigners are afforded the same civil rights as citizens and may seek asylum but may not exercise political rights. The Constitution guarantees equality before the law and prohibits discrimination based on ethnic background, race, sex, language, religion, filiation, political or other views, social origin, economic position, or birth. Women are afforded the same rights as men regardless of their marital status. The Constitution also guarantees citizens freedom to travel nationally and internationally and to choose a place of residence. Equatoguineans are also entitled to a standard of living that insures health, nutrition, education, clothing, housing, medical care, and necessary social services. The family policy contained in the Constitution protects all types of legal marriages equally and recognizes nonattachable and inalienable family patrimony. Children are protected from the time of conception, and all inhabitants are guaranteed a basic state education which is compulsory and free. Efforts are also being made to eradicate illiteracy. Women are insured training and promotion for their integration into the active life and development of the country, and farmers are guaranteed traditional ownership of the lands they possess, although the state retains the right of eminent domain. PMID:12346662
Crushed Salt Constitutive Model
Callahan, G.D.
1999-02-01
The constitutive model used to describe the deformation of crushed salt is presented in this report. Two mechanisms -- dislocation creep and grain boundary diffusional pressure solution -- are combined to form the basis for the constitutive model governing the deformation of crushed salt. The constitutive model is generalized to represent three-dimensional states of stress. Upon complete consolidation, the crushed-salt model reproduces the Multimechanism Deformation (M-D) model typically used for the Waste Isolation Pilot Plant (WIPP) host geological formation salt. New shear consolidation tests are combined with an existing database that includes hydrostatic consolidation and shear consolidation tests conducted on WIPP and southeastern New Mexico salt. Nonlinear least-squares model fitting to the database produced two sets of material parameter values for the model -- one for the shear consolidation tests and one for a combination of the shear and hydrostatic consolidation tests. Using the parameter values determined from the fitted database, the constitutive model is validated against constant strain-rate tests. Shaft seal problems are analyzed to demonstrate model-predicted consolidation of the shaft seal crushed-salt component. Based on the fitting statistics, the ability of the model to predict the test data, and the ability of the model to predict load paths and test data outside of the fitted database, the model appears to capture the creep consolidation behavior of crushed salt reasonably well.
South Africa's Constitutional Change.
ERIC Educational Resources Information Center
Getman, Thomas
1987-01-01
Describes the striking dichotomy of South Africa's beauty and the squalor resulting from the apartheid policies of the government. Reviews reactions of black South Africans to recent constitutional changes and details efforts to secure more sweeping reform. Includes stories of several individuals who have taken actions which oppose the system of…
Sexuality and the Constitution.
ERIC Educational Resources Information Center
Copelon, Rhonda
1987-01-01
Argues for abortion rights and protection of intimate decisions and relationships. Describes the role and position of women in eighteenth century American society as a means of exposing the fallacy of the anti-abortion movement's insistence on adherence to constitutional text. Discusses the recent attempts to overturn the Roe v. Wade ruling. (PS)
ERIC Educational Resources Information Center
Potter, Lee Ann
2007-01-01
In this article, the author describes the experiences middle school students on a field trip to the new Constitution in Action Learning Lab in the Boeing Learning Center at the National Archives can expect. There, middle school students take on the roles of archivists and researchers collecting and analyzing primary sources from the holdings of…
Instabilities and constitutive modelling.
Wilson, Helen J
2006-12-15
The plastics industry today sees huge wastage through product defects caused by unstable flows during the manufacturing process. In addition, many production lines are throughput-limited by a flow speed threshold above which the process becomes unstable. Therefore, it is critically important to understand the mechanisms behind these instabilities. In order to investigate the flow of a molten plastic, the first step is a model of the liquid itself, a relation between its current stress and its flow history called a constitutive relation. These are derived in many ways and tested on several benchmark flows, but rarely is the stability of the model used as a criterion for selection. The relationship between the constitutive model and the stability properties of even simple flows is not yet well understood. We show that in one case a small change to the model, which does not affect the steady flow behaviour, entirely removes a known instability. In another, a change that makes a qualitative difference to the steady flow makes only tiny changes to the stability.The long-term vision of this research is to exactly quantify what are the important properties of a constitutive relation as far as stability is concerned. If we could understand that, not only could very simple stability experiments be used to choose the best constitutive models for a particular material, but our ability to predict and avoid wasteful industrial instabilities would also be vastly improved.
ERIC Educational Resources Information Center
Baxter, Maurice
Changing political, social, economic, and intellectual conditions over the past two hundred years have demanded innovation and adjustment of legal doctrine, thus giving the United States Constitution a character which the framers of the document could not have predicted. Historically, one must not only understand developments since 1787 but also…
A constitutive theory of reacting electrolyte mixtures
NASA Astrophysics Data System (ADS)
Costa Reis, Martina; Wang, Yongqi; Bono Maurizio Sacchi Bassi, Adalberto
2013-11-01
A constitutive theory of reacting electrolyte mixtures is formulated. The intermolecular interactions among the constituents of the mixture are accounted for through additional freedom degrees to each constituent of the mixture. Balance equations for polar reacting continuum mixtures are accordingly formulated and a proper set of constitutive equations is derived with basis in the Müller-Liu formulation of the second law of thermodynamics. Moreover, the non-equilibrium and equilibrium responses of the reacting mixture are investigated in detail by emphasizing the inner and reactive structures of the medium. From the balance laws and constitutive relations, the effects of molecular structure of constituents upon the fluid flow are studied. It is also demonstrated that the local thermodynamic equilibrium state can be reached without imposing that the set of independent constitutive variables is time independent, neither spatially homogeneous nor null. The resulting constitutive relations presented throughout this work are of relevance to many practical applications, such as swelling of clays, developing of bio and polymeric membranes, and use of electrorheological fluids in industrial processes. The first author acknowledges financial support from National Counsel of Technological and Scientific Development (CNPq) and German Academic Exchange Service (DAAD).
Thomas Jefferson and the Constitution.
ERIC Educational Resources Information Center
Peterson, Merrill D.
1987-01-01
Examines Thomas Jefferson's role in the making and interpretation of the United States Constitution. Discusses the dominant features of Jefferson's constitutional theory; the character of Jefferson's presidency; and Jefferson's ongoing concern about constitutional preservation and change. Lists important dates in the history of the constitution.…
The Constitution in Other Lands.
ERIC Educational Resources Information Center
Bill of Rights in Action, 1987
1987-01-01
Designed for classroom teaching, this document contains articles on the new constitutions of Japan, South Korea, and the Philippine Islands which were modeled in part on the U.S. Constitution. These countries' experiences with constitutional government are examined, and whether or not the U.S. Constitution can be a suitable model for other…
Acoustomechanical constitutive theory for soft materials
NASA Astrophysics Data System (ADS)
Xin, Fengxian; Lu, Tian Jian
2016-07-01
Acoustic wave propagation from surrounding medium into a soft material can generate acoustic radiation stress due to acoustic momentum transfer inside the medium and material, as well as at the interface between the two. To analyze acoustic-induced deformation of soft materials, we establish an acoustomechanical constitutive theory by combining the acoustic radiation stress theory and the nonlinear elasticity theory for soft materials. The acoustic radiation stress tensor is formulated by time averaging the momentum equation of particle motion, which is then introduced into the nonlinear elasticity constitutive relation to construct the acoustomechanical constitutive theory for soft materials. Considering a specified case of soft material sheet subjected to two counter-propagating acoustic waves, we demonstrate the nonlinear large deformation of the soft material and analyze the interaction between acoustic waves and material deformation under the conditions of total reflection, acoustic transparency, and acoustic mismatch.
Constitution, 30 September 1987.
1987-01-01
This document reprints provisions of Suriname's 1987 Constitution relating to freedom of movement, equality of the sexes, the right to life, the right to physical integrity, equal opportunity in employment, the family, children, maternity benefits, the right to health care, parental responsibilities, free and compulsory education, illiteracy, and housing. All citizens enjoy freedom of movement within the bounds of the law. All people within the territory may claim protection of their person and property, and discrimination is forbidden on the basis of birth, sex, race, language, religion, education, political beliefs, economic position, or other status. Torture or inhuman treatment and punishment is banned, and the right to life is protected by the law. The state guarantees the right to work, and all employees have the right to equal remuneration for equal work, safe working conditions, and sufficient rest and recreation. The family is protected, and husbands and wives are equal before the law. Children have the right to protection, and working women are entitled to paid maternity leave. The state promotes the right to good health by systematic improvements in living and working conditions and dissemination of health education. The right to education is protected by the provision of free general primary education and efforts of the state to enable all citizens to achieve the highest educational levels possible. The Constitution also calls for the institution of a plan to allow the state to create public housing.
Ethics and constitutional government.
Albright, James A
2007-01-01
The term ethics refers to a set of principles that govern acceptable, proper conduct. Attacks on the Constitution of the United States pose the most serious breach of ethics today. Our country was founded as a republic, not as a democracy. Our Founding Fathers' main concern was to protect citizens from the power of the federal government, so constitutionally, the central government has little or no authority over individual citizens except on federal property. One of the major problems today is the fact that we now have professional politicians. This is due in large part to the lure of financial gain from countless special interest groups. This would change under constitutional law because the federal budget would decrease drastically. Article 1 states that all legislative power is vested in Congress. Congress has only 18 enumerated powers, and almost half of these pertain to defense of the country. Many of our current problems are due to regulatory agencies that have become independent fiefdoms with unconstitutional legislative, as well as executive and judicial, powers. The regulatory agency most relevant to medicine, both clinical care and research, is the FDA. It is now obvious that its basic structure needs to be changed or abolished because its actions are identical to those inherent in authoritarian systems. Constructive change could come from Congress, but it would be most desirable if the Supreme Court would take the lead and reestablish the authority of the Constitution as the Supreme Law of the Land. The FDA's function could be limited to the determination of safety, but preferably its mission would be altered to that of product certification. Defenders of the current system claim that such a drastic change would be too dangerous and their prime example is thalidomide. But it is now known that the market has already solved that problem prior to the government-imposed sanctions. Realistically, market forces and their ramifications, including our legal
Ethics and constitutional government.
Albright, James A
2007-01-01
The term ethics refers to a set of principles that govern acceptable, proper conduct. Attacks on the Constitution of the United States pose the most serious breach of ethics today. Our country was founded as a republic, not as a democracy. Our Founding Fathers' main concern was to protect citizens from the power of the federal government, so constitutionally, the central government has little or no authority over individual citizens except on federal property. One of the major problems today is the fact that we now have professional politicians. This is due in large part to the lure of financial gain from countless special interest groups. This would change under constitutional law because the federal budget would decrease drastically. Article 1 states that all legislative power is vested in Congress. Congress has only 18 enumerated powers, and almost half of these pertain to defense of the country. Many of our current problems are due to regulatory agencies that have become independent fiefdoms with unconstitutional legislative, as well as executive and judicial, powers. The regulatory agency most relevant to medicine, both clinical care and research, is the FDA. It is now obvious that its basic structure needs to be changed or abolished because its actions are identical to those inherent in authoritarian systems. Constructive change could come from Congress, but it would be most desirable if the Supreme Court would take the lead and reestablish the authority of the Constitution as the Supreme Law of the Land. The FDA's function could be limited to the determination of safety, but preferably its mission would be altered to that of product certification. Defenders of the current system claim that such a drastic change would be too dangerous and their prime example is thalidomide. But it is now known that the market has already solved that problem prior to the government-imposed sanctions. Realistically, market forces and their ramifications, including our legal
1989-01-01
This document contains provisions of Cambodia's Constitution of May 5, 1989. Article 7 gives men and women equal rights in marriage and the family, calls for monogamous marriages, and affords social protection to mothers and children. Article 8 guides parent-child relationships. The 14th article defines state property, and the 15th gives citizens full rights to own, use, and inherit land. The use of agricultural and forested land can only be changed with permission. Article 22 assigns educational responsibilities to the state, including free elementary education and a gradual expansion of higher education. Adult literacy classes are also promoted. Article 26 guarantees free medical consultations, and article 27 gives women a 90-day paid maternity leave. Breast-feeding women are also given special privileges. Article 33 guarantees the right to pay equity and to social security benefits. Article 36 grants the freedom to travel, the inviolability of homes, and privacy in correspondence of all types.
1989-01-01
This document contains major provisions of the constitution adopted by Brazil on 5 October 1988. This constitution seeks to promote the welfare of all citizens without discrimination. The equality of all citizens is guaranteed, and the equal rights of women are specifically mentioned. Property rights are also guaranteed and defined. Female inmates are granted the right to remain with their children while breast feeding. Workers are guaranteed a minimum wage, a family allowance for dependents, maternity/paternity leave, specific incentives to protect the labor market for women, retirement benefits, free day care for preschool-age children, pay equity, and equal rights between tenured and sporadically employed workers. Agrarian reform provisions are given, including the authority to expropriate land. Social and economic policies to promote health are called for, and public health services are to be decentralized, to be integrated, and to foster community participation. Pension plan and social assistance provisions are outlined as are duties of the state in regard to education. The amount of money to be dedicated to education is set out, and a national educational plan is called for to achieve such goals as the eradication of illiteracy, the universalization of school attendance, the improvement of instruction, and the provision of vocational training. Specific measures are set out to protect and preserve the environment. Family policy deals with issues of marriage, the definition of a family, divorce, the right to family planning services, and the deterrence of domestic violence. Social protection provisions cover mothers and children, handicapped persons, and protection of minors. Finally, the customs and rights of Indians are protected, with special provisions given to protect land tenure and to protect the rights of Indians in water resource development and prospecting and mining activities. PMID:12344286
1989-01-01
This document contains major provisions of the constitution adopted by Brazil on 5 October 1988. This constitution seeks to promote the welfare of all citizens without discrimination. The equality of all citizens is guaranteed, and the equal rights of women are specifically mentioned. Property rights are also guaranteed and defined. Female inmates are granted the right to remain with their children while breast feeding. Workers are guaranteed a minimum wage, a family allowance for dependents, maternity/paternity leave, specific incentives to protect the labor market for women, retirement benefits, free day care for preschool-age children, pay equity, and equal rights between tenured and sporadically employed workers. Agrarian reform provisions are given, including the authority to expropriate land. Social and economic policies to promote health are called for, and public health services are to be decentralized, to be integrated, and to foster community participation. Pension plan and social assistance provisions are outlined as are duties of the state in regard to education. The amount of money to be dedicated to education is set out, and a national educational plan is called for to achieve such goals as the eradication of illiteracy, the universalization of school attendance, the improvement of instruction, and the provision of vocational training. Specific measures are set out to protect and preserve the environment. Family policy deals with issues of marriage, the definition of a family, divorce, the right to family planning services, and the deterrence of domestic violence. Social protection provisions cover mothers and children, handicapped persons, and protection of minors. Finally, the customs and rights of Indians are protected, with special provisions given to protect land tenure and to protect the rights of Indians in water resource development and prospecting and mining activities.
Hammerand, Daniel Carl; Scherzinger, William Mark
2007-09-01
The Library of Advanced Materials for Engineering (LAME) provides a common repository for constitutive models that can be used in computational solid mechanics codes. A number of models including both hypoelastic (rate) and hyperelastic (total strain) constitutive forms have been implemented in LAME. The structure and testing of LAME is described in Scherzinger and Hammerand ([3] and [4]). The purpose of the present report is to describe the material models which have already been implemented into LAME. The descriptions are designed to give useful information to both analysts and code developers. Thus far, 33 non-ITAR/non-CRADA protected material models have been incorporated. These include everything from the simple isotropic linear elastic models to a number of elastic-plastic models for metals to models for honeycomb, foams, potting epoxies and rubber. A complete description of each model is outside the scope of the current report. Rather, the aim here is to delineate the properties, state variables, functions, and methods for each model. However, a brief description of some of the constitutive details is provided for a number of the material models. Where appropriate, the SAND reports available for each model have been cited. Many models have state variable aliases for some or all of their state variables. These alias names can be used for outputting desired quantities. The state variable aliases available for results output have been listed in this report. However, not all models use these aliases. For those models, no state variable names are listed. Nevertheless, the number of state variables employed by each model is always given. Currently, there are four possible functions for a material model. This report lists which of these four methods are employed in each material model. As far as analysts are concerned, this information is included only for the awareness purposes. The analyst can take confidence in the fact that model has been properly implemented
How Democratic Is the Constitution?
ERIC Educational Resources Information Center
Goldwin, Robert A., Ed.; Schambra, William A., Ed.
Designed to help prepare the nation for a thoughtful observance of the Constitutional bicentennial, this publication contains seven essays on the topic of democracy and the Constitution. "Democracy and the Constitution" (Gordon S. Wood) looks at the popular and democratic rhetoric used to justify the federalist system in the late 1700's. "Decent,…
A comparative study on plaque vulnerability using constitutive equations.
Karimi, A; Navidbakhsh, M; Faghihi, S
2014-03-01
Atherosclerosis is the most serious and common form of cardiovascular disease in which plaque builds up inside the arteries. Peak plaque stress is considered as the main reason for plaque rupture, which results in heart attack and stroke. In the current research, the finite element method is used to anticipate plaque vulnerability, using human samples. A total of 23 healthy and atherosclerotic human coronary arteries (14 healthy and 9 atherosclerotic) were removed within 5 h postmortem. The samples were mounted on a uniaxial tensile test machine and the obtained mechanical properties were used in finite element models. The peak plaque stresses for the Ogden hyperelastic model were compared to the Mooney-Rivlin and Neo-Hookean outcomes. The results indicated that hypocellular plaque in all three models has the highest stress values compared to the cellular and calcified ones and, as a result, is quite prone to rupture. The calcified plaque type, in contrast, has the lowest stress values and remains stable. The results can be used in plaque vulnerability prediction and have clinical implications for interventions and surgeries such as balloon-angioplasty, cardiopulmonary bypass and stenting.
Constitution, 3 February 1987.
1987-01-01
This document contains provisions of the 1987 Constitution of the Philippines. The state policies reprinted from Article 2 note that the state recognizes the sanctity of family life and protects the life of the mother and of the unborn from conception. Women and men are afforded equality before the law. The state prioritizes education, science and technology, arts, culture, and sports and promotes comprehensive rural development and agrarian reform. Provisions reprinted from Article 13 (Social Justice and Human Rights) cover agrarian and natural resources reform, urban land reform and housing, health, and protection of women in the workforce. Sections from Article 14 (Education, Science and Technology, Arts, Culture, and Sports) set forth the state's duty to make quality education accessible to all citizens through a compulsory system of free public education, provision of incentives to deserving students, encouragement of informal education, and provision of adult education. Article 15, on the family, recognizes the family as the foundation of the nation and marriage as the foundation of the family. Spouses have the right to found a family, children have the right to appropriate care, the family has the right to a living wage and income, families or family associations have the right to participate in the planning and implementation of policies and programs that affect them, and the family has the duty to care for its elderly.
Amendment to the Constitution.
1988-01-01
This Amendment rewrites Clause 4 of Article 10 of the Chinese Constitution to permit the right of land use to be transferred by lease in accordance with the law. In December 1988, the Government also enacted legislation amending the Land Management Law so as to allow for the transfer of Land. See Renmin Ribao (Beijing), 31 December 1988, p. 4; Foreign Broadcast Information Service, FBIS-CHI-89-003, 5 January 1989, pp. 38-39. Provisional Regulations on the Land Use Tax in Urban Areas were promulgated on 27 September 1988. See Xinhua Domestic Service (Beijing), 4 October 1988, Foreign Broadcast Information Service, FBIS-CHI-88-197, 12 October 1988, pp. 26-27, and Xinhua (Beijing), 4 October 1988, FBIS-CHI-88-193, 5 October 1988, pp. 20. Provisional Tax Regulations on Farmland Occupation and Use were proclaimed on 1 April 1987. See Xinhua Domestic Service (Beijing), 19 April 1987; Joint Publications Research Service, China, 22 April 1987, pp. K33-K35. PMID:12289449
Rapid implementation of advanced constitutive models
NASA Astrophysics Data System (ADS)
Starman, Bojan; Halilovič, Miroslav; Vrh, Marko; Štok, Boris
2013-12-01
This paper presents a methodology based on the NICE integration scheme [1, 2] for simple and rapid numerical implementation of a class of plasticity constitutive models. In this regard, an algorithm is purposely developed for the implementation of newly developed advanced constitutive models into explicit finite element framework. The methodology follows the organization of the problem state variables into an extended form, which allows the constitutive models' equations to be organized in such a way, that the algorithm can be optionally extended with minimal effort to integrate also evolution equations related to a description of other specific phenomena, such as damage, distortional hardening, phase transitions, degradation etc. To confirm simplicity of the program implementation, computational robustness, effectiveness and improved accuracy of the implemented integration algorithm, a deep drawing simulation of the cylindrical cup is considered as the case study, performed in ABAQUS/Explicit. As a fairly complex considered model, the YLD2004-18p model [3, 4] is first implemented via external subroutine VUMAT. Further, to give additional proof of the simplicity of the proposed methodology, a combination of the YLD2004-18p model and Gurson-Tvergaard-Needleman model (GTN) is considered. As demonstrated, the implementation is really obtained in a very simple way.
Constitution, 1989. [Selected provisions].
1989-01-01
Chapter XII of the Hungarian Constitution, 1989, details the Fundamental Rights and Duties of Citizens. Everyone lawfully within the territory of Hungary has the right to liberty of movement and the freedom to choose his or her residence, except when restricted by law, including the right to leave his or her residence or county. The Republic of Hungary grants asylum to foreign citizens who were persecuted for racial, religious ethnic, linguistic, or political reasons. Men and women shall equally enjoy all civil, political, economic, social and political rights. Mothers are entitled to special care and protection before and after childbirth; women and juveniles are protected at work by special regulations. Every child has the right to special care an assistance from his or her family, the State, and society, for appropriate physical, spiritual, and moral development. Parents shall decide the kind of education their children receive. Hungary grants equal rights to all person within its territories, without regard to race, color, sex, language, religion, political, or other opinion, national, and social origin, property, birth and other status. Prejudicial discrimination shall be severely punished. Everyone has the right to work, to the free choice of employment and profession and to equal pay for equal work. Citizens have the right to social security, including social services necessary in old age, sickness, disability, widowhood, orphanhood an unemployment through no fault of their own. Hungary guarantees the right to culture for its citizens and realized this right by free and compulsory elementary education, by secondary and higher education which is accessible to all on the basis of capacity, and by the financial support of those receiving an education.
NASA Astrophysics Data System (ADS)
McCarron, T.; Gaidies, F.
2013-12-01
Growth zoning developed in a population of garnet porphyroblasts of a metapelite from the Grenville Province of southeastern Ontario has been used to infer the metamorphic P-T-t history of the garnet-bearing rock. The sample is a garnet-biotite-staurolite bearing schist of the Flinton Group, a package of metasediments in southeastern Ontario metamorphosed during the Grenville Orogeny between ca. 1080-980 Ma. Characterization of the garnet population with high-resolution X-ray micro-computed tomography revealed a unimodal, slightly positively skewed crystal size distribution (CSD). A representative set of garnet porphyroblasts ranging from 4000 to 200 μm in diameter from the different size classes of the CSD were centrally sectioned. Electron probe micro analyses across the centrally sectioned garnet porphyroblasts revealed decreasing Xsps and Xgrs and increasing Xalm and Xpyp from core to rim consistent with growth zoning. Garnet growth simulations with THERIA_G (Gaidies et al., 2008) successfully reproduced the observed growth zoning in the differently sized grains allowing to derive a significant part of the rock's metamorphic P-T-t history. Large porphyroblasts of the population were used to determine a clockwise P-T path over the interval 3.7 to 5.9 kbar and 512 to 615°C whereas modification of growth zoning via intracrystalline diffusion in relatively small porphyroblasts was used to infer an average heating rate of 2°C Ma-1. This suggests a timescale of ca. 53 Ma for garnet growth and an average growth rate of 30 μm Ma-1. Using LA-ICP-MS U-Pb geochronology, a major age population at 977×4 Ma was identified for metamorphic monazite commonly included in the outer 200 μm of the garnet grains. That age is interpreted to represent monazite growth at the expense of allanite and apatite late in garnet's growth history providing an absolute calibration for the relative timescales predicted through THERIA_G modeling. Gaidies, F., de Capitani, C. & Abart, R
Essential Medicines in National Constitutions
Toebes, Brigit; Hogerzeil, Hans
2016-01-01
Abstract A constitutional guarantee of access to essential medicines has been identified as an important indicator of government commitment to the progressive realization of the right to the highest attainable standard of health. The objective of this study was to evaluate provisions on access to essential medicines in national constitutions, to identify comprehensive examples of constitutional text on medicines that can be used as a model for other countries, and to evaluate the evolution of constitutional medicines-related rights since 2008. Relevant articles were selected from an inventory of constitutional texts from WHO member states. References to states’ legal obligations under international human rights law were evaluated. Twenty-two constitutions worldwide now oblige governments to protect and/or to fulfill accessibility of, availability of, and/or quality of medicines. Since 2008, state responsibilities to fulfill access to essential medicines have expanded in five constitutions, been maintained in four constitutions, and have regressed in one constitution. Government commitments to essential medicines are an important foundation of health system equity and are included increasingly in state constitutions. PMID:27781006
NASA Astrophysics Data System (ADS)
Zhang, Guibin; Niu, Yaoling; Song, Shuguang; Zhang, Lifei; Tian, Zuolin; Christy, Andrew G.; Han, Lei
2015-06-01
We have studied trace element behavior and timing of decompression melting of UHP rocks during exhumation recorded in the magmatic products, i.e., the melt phase (leucosomes), cumulate (garnetite) and residue (amphibolitized eclogite) from a single outcrop in the south Dulan area, North Qaidam UHPM belt, NW China. Two distinct episodes of partial melting are recognized. First, Grt-free tonalitic-trondhjemitic leucosome melts with higher silica crystallized at 424.0 ± 2.7 Ma. Garnets grew in the leucosome melt but fractionated out to form garnetite cumulates along with Ti-rich phases (rutile and titanite), strengthening the adakitic signature of the leucosome. Later Grt-bearing leucosome melts with an age of 412.4 ± 2.9 Ma cross-cut boudins and layers of amphibolitized eclogite. Geochemical investigation of bulk-rocks and in situ minerals verifies the genetic relationship between the amphibolitized eclogite and the tonalitic-trondhjemitic melts. Zircons from the amphibolitized eclogite have older (> 700 Ma) protolith ages, with subsequent eclogite-facies metamorphism, retrograde granulite-facies overprinting and partial melting. Phase modeling and Zr-in-rutile thermometry calculations in combination with zircon geochronology reveal the evolution P-T-t path for the exhumation and the partial melting of the deeply subducted continental crust at the North Qaidam subduction zone in the Early Paleozoic.
Constitutional Issues--Watergate and the Constitution. Teaching with Documents.
ERIC Educational Resources Information Center
National Archives and Records Administration, Washington, DC.
When U.S. President Richard Nixon resigned in 1974 in the wake of the Watergate scandal, it was only the second time that impeachment of a president had been considered. Although the U.S. Constitution has provisions for a person removed from office to be indicted, there are no guidelines in the Constitution about a President who has resigned. The…
The Origins of the Constitution.
ERIC Educational Resources Information Center
Grindle, Diane
1987-01-01
Maintains that there were three forces operating in colonial American culture which led to the drafting of the Constitution. These were: English law and tradition, the lifestyle of the colonies, and the Enlightenment. Provides examples of how these forces were expressed in the events surrounding the birth of the United States Constitution. (JDH)
Constitution And Bylaws: 2004 Edition
ERIC Educational Resources Information Center
Distance Education and Training Council, 2004
2004-01-01
This document contains the constitution and bylaws of the Distance Education and Training Council. The constitution and bylaws include 13 articles. Sections include: Name; Mission and Goals; Administration of the Council; Membership; Meetings; The Commission; Terms of Office; Officers; Committees; Compensation; Dues and Assessments; Miscellaneous…
The Constitution and Its Critics
ERIC Educational Resources Information Center
Main, Thomas J.
2011-01-01
In planning a freshman undergraduate curriculum with colleagues recently, the question arose as to what type of understanding educators wanted to impart to their students about the Constitution. The alleged defects of the Constitution that these books point to are wide-ranging and can be classified into various categories. Some problems--such as…
The Constitution and American Radicalism.
ERIC Educational Resources Information Center
Lobel, Jules
1987-01-01
Discusses the history of the following movements' attitudes towards the Constitution: (1) abolition; (2) feminism; (3) trade unions; (4) socialism and communism; and (5) civil rights and anti-war. Maintains that the tensions in these movements' towards the Constitution represent basic contradictions in the document itself. (PS)
Constitutional Change: A Case Study.
ERIC Educational Resources Information Center
Christofferson, Walter D.; Pergande, Donald J.
1987-01-01
Presents a lesson for secondary students which teaches that the U.S. Constitution has changed in a variety of ways and that it has a direct effect upon the lives of citizens. Provides a worksheet and a lecture outline covering three methods of constitutional change and Supreme Court cases such as Dred Scott and Brown vs. Board of Education. (GEA)
Probabilistic constitutive relationships for material strength degradation models
NASA Technical Reports Server (NTRS)
Boyce, L.; Chamis, C. C.
1989-01-01
In the present probabilistic methodology for the strength of aerospace propulsion system structural components subjected to such environmentally-induced primitive variables as loading stresses, high temperature, chemical corrosion, and radiation, time is encompassed as an interacting element, allowing the projection of creep and fatigue effects. A probabilistic constitutive equation is postulated to account for the degradation of strength due to these primitive variables which may be calibrated by an appropriately curve-fitted least-squares multiple regression of experimental data. The resulting probabilistic constitutive equation is embodied in the PROMISS code for aerospace propulsion component random strength determination.
The anisotropic material constitutive models for the human cornea.
Li, Long-yuan; Tighe, Brian
2006-03-01
This paper presents an anisotropic analysis model for the human cornea. The model is based on the assumption that the fibrils in the cornea are organised into lamellae, which may have preferential orientation along the superior-inferior and nasal-temporal directions, while the alignment of lamellae with different orientations is assumed to be random. Hence, the cornea can be regarded as a laminated composite shell. The constitutive equation describing the relationships between membrane forces, bending moments, and membrane strains, bending curvatures are derived. The influences of lamella orientations and the random alignment of lamellae on the stiffness coefficients of the constitutive equation are discussed. PMID:16426861
NASA Technical Reports Server (NTRS)
Allen Phillip A.; Wilson, Christopher D.
2003-01-01
The development of a pressure-dependent constitutive model with combined multilinear kinematic and isotropic hardening is presented. The constitutive model is developed using the ABAQUS user material subroutine (UMAT). First the pressure-dependent plasticity model is derived. Following this, the combined bilinear and combined multilinear hardening equations are developed for von Mises plasticity theory. The hardening rule equations are then modified to include pressure dependency. The method for implementing the new constitutive model into ABAQUS is given.
Constitutive relations in optics in terms of geometric algebra
NASA Astrophysics Data System (ADS)
Dargys, A.
2015-11-01
To analyze the electromagnetic wave propagation in a medium the Maxwell equations should be supplemented by constitutive relations. At present the classification of linear constitutive relations is well established in tensorial-matrix and exterior p-form calculus. Here the constitutive relations are found in the context of Clifford geometric algebra. For this purpose Cl1,3 algebra that conforms with relativistic 4D Minkowskian spacetime is used. It is shown that the classification of linear optical phenomena with the help of constitutive relations in this case comes from the structure of Cl1,3 algebra itself. Concrete expressions for constitutive relations which follow from this algebra are presented. They can be applied in calculating the propagation properties of electromagnetic waves in any anisotropic, linear and nondissipative medium.
Constitutive modeling for isotropic materials (HOST)
NASA Technical Reports Server (NTRS)
Lindholm, Ulric S.; Chan, Kwai S.; Bodner, S. R.; Weber, R. M.; Walker, K. P.; Cassenti, B. N.
1984-01-01
The results of the first year of work on a program to validate unified constitutive models for isotropic materials utilized in high temperature regions of gas turbine engines and to demonstrate their usefulness in computing stress-strain-time-temperature histories in complex three-dimensional structural components. The unified theories combine all inelastic strain-rate components in a single term avoiding, for example, treating plasticity and creep as separate response phenomena. An extensive review of existing unified theories is given and numerical methods for integrating these stiff time-temperature-dependent constitutive equations are discussed. Two particular models, those developed by Bodner and Partom and by Walker, were selected for more detailed development and evaluation against experimental tensile, creep and cyclic strain tests on specimens of a cast nickel base alloy, B19000+Hf. Initial results comparing computed and test results for tensile and cyclic straining for temperature from ambient to 982 C and strain rates from 10(exp-7) 10(exp-3) s(exp-1) are given. Some preliminary date correlations are presented also for highly non-proportional biaxial loading which demonstrate an increase in biaxial cyclic hardening rate over uniaxial or proportional loading conditions. Initial work has begun on the implementation of both constitutive models in the MARC finite element computer code.
NASA Astrophysics Data System (ADS)
Jeanniot, Ludovic; Kusznir, Nick; Manatschal, Gianreto; Mohn, Geoffroy; Beltrando, Marco
2014-05-01
Mantle exhumation and hyper-extended crust, as observed on the Iberia-Newfoundland conjugate margins, are key components of both present-day and fossil analogue magma-poor rifted margins. Conceptual models of the Alpine Tethys paleogeography evolution show a complex subsidence history, determined by the nature and composition of sedimentary, crustal and mantle rocks in the Alpine domains (Mohn et al., 2010). The relative timing of crustal rupture and decompressional melt initiation and inherited mantle composition control whether mantle exhumation may occur; the presence or absence of exhumed mantle therefore provides useful information on the timing of these events and constraints on lithosphere deformation modes and composition. A single mode of lithosphere deformation leading to continental breakup and sea-floor spreading cannot explain observations. We have determined the sequence of lithosphere deformation modes for the fossil Alpine Tethys margin using a numerical model of the temporal and spatial evolution of lithosphere deformation; the model has been calibrated against observations of subsidence and P-T-t history for the Alpine Tethys margin. A 2D finite element viscous flow model (FeMargin) is used to generate flow fields for a sequence of lithosphere deformation modes, which are used to advect lithosphere and asthenosphere temperature and material. FeMargin is kinematically driven by divergent deformation in the topmost 15-20 km of the lithosphere inducing passive upwelling beneath that layer; the upper lithosphere is assumed to deform by extensional faulting and magmatic intrusions, consistent with observations of deformation processes occurring at slow spreading ocean ridges (Cannat, 1996). We also include buoyancy enhanced upwelling in the kinematic model as proposed by Braun et al. (2000). We generate melt by decompressional melting using the parameterization and methodology of Katz et al. (2003). In the modelling of the Alpine Tethys margin
NASA Astrophysics Data System (ADS)
Massonne, Hans-Joachim
2014-11-01
It is demonstrated here that medium-high grade metapsammopelites contain a wealth of information to derive a well-constrained P-T-t path relevant for the understanding of the geodynamics resulting in a collisional orogen. The presented example is related to three samples from the Migmatite gneiss zone of the Jubrique Unit, being part of the Alpujárride Complex half way between Malaga and Cadiz. The rocks were studied to determine their pressure (P)-temperature (T) evolution mainly on the basis of the zonation of mm-sized garnet and contoured P-T pseudosections calculated with PERPLE_X. In addition, monazite was dated with the electron microprobe. Ca-poor garnet cores yielded granulite-facies P-T conditions around 0.7 GPa and 800 °C. This metamorphic event occurred in late Hercynian times [287 ± 9 (2σ) Ma] according to monazite enclosed in such garnet cores. The cores are surrounded by a Ca-richer garnet zone, which points to a high-pressure (HP) event close to 1.3 GPa and temperatures above 650 °C. At this stage, melting occurred as indicated by abundant melt inclusions in the Ca-rich garnet zone. Subsequently, the rocks were exhumed and heated to peak temperatures of 740 °C. The final metamorphic stage is characterised by late sillimanite and an outermost garnet rim which is poor in Ca. The melting event is late Alpine confirmed by age dating on monazite in the rock matrix. Similar conditions of a late Alpine HP event were also reported from other areas of the Alpujárride Complex. As the studied rocks never reached P-T conditions of the diamond stability field, it is concluded that the previously reported nanodiamonds in these rocks either grew metastably or were artificially introduced into rock thin-sections.
Remarks on turbulent constitutive relations
NASA Technical Reports Server (NTRS)
Shih, Tsan-Hsing; Lumley, John L.
1993-01-01
The paper demonstrates that the concept of turbulent constitutive relations can be used to construct general models for various turbulent correlations. Some of the Generalized Cayley-Hamilton formulas for relating tensor products of higher extension to tensor products of lower extension are introduced. The combination of dimensional analysis and invariant theory can lead to 'turbulent constitutive relations' (or general turbulence models) for, in principle, any turbulent correlations. As examples, the constitutive relations for Reynolds stresses and scalar fluxes are derived. The results are consistent with ones from Renormalization Group (RNG) theory and two-scale Direct-Interaction Approximation (DIA) method, but with a more general form.
Abnormal human sex chromosome constitutions
1993-12-31
Chapter 22, discusses abnormal human sex chromosome constitution. Aneuploidy of X chromosomes with a female phenotype, sex chromosome aneuploidy with a male phenotype, and various abnormalities in X chromosome behavior are described. 31 refs., 2 figs.
The Constitution's Prescription for Freedom.
ERIC Educational Resources Information Center
Peach, Lucinda
1986-01-01
Examines how the framers of the Constitution came to choose our system of government, how that system was designed to function, and how the separation of powers has served to maintain our democracy despite attempts to violate it. (JDH)
Constitutive modeling for isotropic materials
NASA Technical Reports Server (NTRS)
Ramaswamy, V. G.; Vanstone, R. H.; Dame, L. T.; Laflen, J. H.
1984-01-01
The unified constitutive theories for application to typical isotropic cast nickel base supperalloys used for air-cooled turbine blades were evaluated. The specific modeling aspects evaluated were: uniaxial, monotonic, cyclic, creep, relaxation, multiaxial, notch, and thermomechanical behavior. Further development of the constitutive theories to model thermal history effects, refinement of the material test procedures, evaluation of coating effects, and verification of the models in an alternate material will be accomplished in a follow-on for this base program.
Activities report of PTT Research
NASA Astrophysics Data System (ADS)
In the field of postal infrastructure research, activities were performed on postcode readers, radiolabels, and techniques of operations research and artificial intelligence. In the field of telecommunication, transportation, and information, research was made on multipurpose coding schemes, speech recognition, hypertext, a multimedia information server, security of electronic data interchange, document retrieval, improvement of the quality of user interfaces, domotics living support (techniques), and standardization of telecommunication prototcols. In the field of telecommunication infrastructure and provisions research, activities were performed on universal personal telecommunications, advanced broadband network technologies, coherent techniques, measurement of audio quality, near field facilities, local beam communication, local area networks, network security, coupling of broadband and narrowband integrated services digital networks, digital mapping, and standardization of protocols.
Covariant constitutive relations and relativistic inhomogeneous plasmas
Gratus, J.; Tucker, R. W.
2011-04-15
The notion of a 2-point susceptibility kernel used to describe linear electromagnetic responses of dispersive continuous media in nonrelativistic phenomena is generalized to accommodate the constraints required of a causal formulation in spacetimes with background gravitational fields. In particular the concepts of spatial material inhomogeneity and temporal nonstationarity are formulated within a fully covariant spacetime framework. This framework is illustrated by recasting the Maxwell-Vlasov equations for a collisionless plasma in a form that exposes a 2-point electromagnetic susceptibility kernel in spacetime. This permits the establishment of a perturbative scheme for nonstationary inhomogeneous plasma configurations. Explicit formulae for the perturbed kernel are derived in both the presence and absence of gravitation using the general solution to the relativistic equations of motion of the plasma constituents. In the absence of gravitation this permits an analysis of collisionless damping in terms of a system of integral equations that reduce to standard Landau damping of Langmuir modes when the perturbation refers to a homogeneous stationary plasma configuration. It is concluded that constitutive modeling in terms of a 2-point susceptibility kernel in a covariant spacetime framework offers a natural extension of standard nonrelativistic descriptions of simple media and that its use for describing linear responses of more general dispersive media has wide applicability in relativistic plasma modeling.
Constitutive representation of damage development and healing in WIPP salt
Chan, K.S.; Bodner, S.R.; Fossum, A.F
1994-12-31
There has been considerable interest in characterizing and modeling the constitutive behavior of rock salt with particular reference to long-term creep and creep failure. The interest is motivated by the projected use of excavated rooms in salt rock formations as repositories for nuclear waste. It is presumed that closure of those rooms by creep ultimately would encapsulate the waste material, resulting in its effective isolation. A continuum mechanics approach for treating damage healing is formulated as part of a constitutive model for describing coupled creep, fracture, and healing in rock salt. Formulation of the healing term is, described and the constitutive model is evaluated against experimental data of rock salt from the Waste Isolation Pilot Plant (WIPP) site. The results indicate that healing anistropy in WIPP salt can be modeled with an appropriate power-conjugate equivalent stress, kinetic equation, and evolution equation for damage healing.
Immigration, naturalization and the Constitution.
Vecoli, R J
1987-03-01
This essay focuses upon major decisions made by the US government affecting aliens and the constitutional bases for them. These include: 1) the admission and exclusion of aliens, 2) the deportation of aliens, 3) the rights of aliens within the US, and 4) naturalization and denaturalization. The recourse to the extra-constitutional doctrine of sovereignty by the Supreme Court was the source of the plenary power of the Congress over immigration, thus denying the authority of the judiciary to extend the guarantees of due process of law and the equal protection of the law to aliens. The courts in the last 2 decades have assumed a more activist posture with respect to the rights of aliens, extending a greater degree of constitutional protection to the security of acquired citizenship and to the rights of due process and equal protection of foreigners, even to undocumented aliens.
Derivation of stiffness matrix in constitutive modeling of magnetorheological elastomer
NASA Astrophysics Data System (ADS)
Leng, D.; Sun, L.; Sun, J.; Lin, Y.
2013-02-01
Magnetorheological elastomers (MREs) are a class of smart materials whose mechanical properties change instantly by the application of a magnetic field. Based on the specially orthotropic, transversely isotropic stress-strain relationships and effective permeability model, the stiffness matrix of constitutive equations for deformable chain-like MRE is considered. To valid the components of shear modulus in this stiffness matrix, the magnetic-structural simulations with finite element method (FEM) are presented. An acceptable agreement is illustrated between analytical equations and numerical simulations. For the specified magnetic field, sphere particle radius, distance between adjacent particles in chains and volume fractions of ferrous particles, this constitutive equation is effective to engineering application to estimate the elastic behaviour of chain-like MRE in an external magnetic field.
Multiaxial probabilistic elastic-plastic constitutive simulations of soils
NASA Astrophysics Data System (ADS)
Sadrinezhad, Arezoo
Fokker-Planck-Kolmogorov (FPK) equation approach has recently been developed to simulate elastic-plastic constitutive behaviors of materials with uncertain material properties. The FPK equation approach transforms the stochastic constitutive rate equation, which is a stochastic, nonlinear, ordinary differential equation (ODE) in the stress-pseudo time space into a second-order accurate, deterministic, linear FPK partial differential equation (PDE) in the probability density of stress-pseudo time space. This approach does not suffer from the drawbacks of the traditional approaches such as the Monte Carlo approach and the perturbation approach for solving nonlinear ODEs with random coefficients. In this study, the existing one dimensional FPK framework for probabilistic constitutive modeling of soils is extended to multi--dimension. However, the multivariate FPK PDEs cannot be solved using the traditional mathematical techniques such as finite difference techniques due to their high computational cost. Therefore, computationally efficient algorithms based on the Fourier spectral approach are developed for solving a class of FPK PDEs that arises in probabilistic elasto-plasticity. This class includes linear FPK PDEs in (stress) space and (pseudo) time - having space-independent but time-dependent, and both space- and time-dependent coefficients - with impulse initial conditions and reflecting boundary conditions. The solution algorithms, rely on first mapping the stress space of the governing PDE between 0 and 2pi using the change of coordinates rule, followed by approximating the solution of the PDE in the 2pi-periodic domain by a finite Fourier series in the stress space and unknown time-dependent solution coefficients. Finally, the time-dependent solution coefficients are obtained from the initial condition. The accuracy and efficiency of the developed algorithms are tested. The developed algorithms are used to simulate uniaxial and multiaxial, monotonic and cyclic
Constitutional Reform of School Finance.
ERIC Educational Resources Information Center
Alexander, Kern, Ed.; Jordan, K. Forbis, Ed.
This book contains conference papers by experts in educational administration, law, and economics. Six of the papers are devoted to a legal analysis of fiscal inequality among school attendance units, school districts, and States. These contributions are: (1) K. Forbis Jordan and Kern Alexander, "Constitutional Methods of Financing Public…
Civil Liberties under State Constitutions.
ERIC Educational Resources Information Center
Tarr, G. Alan
1988-01-01
Discusses "new judicial federalism" as the rediscovery of state bills of rights for protecting civil liberties. Analyzes the differences in protection under state and federal bills of rights. Recommends that the growing importance of state constitutions be included in the political science curriculum and suggests bibliographic sources to be used.…
Take Advantage of Constitution Day
ERIC Educational Resources Information Center
McCune, Bonnie F.
2008-01-01
The announcement of the mandate for Constitution and Citizenship Day shortly before September, 2005, probably led to groans of dismay. Not another "must-do" for teachers and schools already stressed by federal and state requirements for standardized tests, increasingly rigid curricula, and scrutiny from the public and officials. But the idea and…
Lazy Elephants and the Constitution.
ERIC Educational Resources Information Center
Hantula, James
1989-01-01
Depicts an eighth grade unit utilizing the production of a newspaper to teach U.S. history, 1787 to 1791, in a combined social studies and language arts class at Malcolm Price Laboratory School (Iowa). Two teachers used both large- and small-group instruction to focus on the development of the U.S. Constitution. (LS)
Young, C.W.
1997-10-01
In 1967, Sandia National Laboratories published empirical equations to predict penetration into natural earth materials and concrete. Since that time there have been several small changes to the basic equations, and several more additions to the overall technique for predicting penetration into soil, rock, concrete, ice, and frozen soil. The most recent update to the equations was published in 1988, and since that time there have been changes in the equations to better match the expanding data base, especially in concrete penetration. This is a standalone report documenting the latest version of the Young/Sandia penetration equations and related analytical techniques to predict penetration into natural earth materials and concrete. 11 refs., 6 tabs.
Remarks on Constitutive Laws for Dry Granular Materials
NASA Astrophysics Data System (ADS)
Giovine, Pasquale
2010-05-01
In this paper we resume some remarks upon the model for dry granular materials formulated in [19] which generalized the distributed theory of Goodman & Cowin [24] by allowing the possibility of rotations of grains. Firstly, we reconsider the balance equations for micromomentum and energy by bearing the bulk and rotational effects of granules in mind; secondly, we derive the constitutive relations and define the dissipation function; thirdly, we specify an appropriate equilibrium state for dry granular materials in order to obtain additional informations on constitutive fields.
Sex Differences in Constitutive Autophagy
Oliván, Sara; Calvo, Ana Cristina; Manzano, Raquel; Zaragoza, Pilar
2014-01-01
Sex bias has been described nowadays in biomedical research on animal models, although sexual dimorphism has been confirmed widely under pathological and physiological conditions. The main objective of our work was to study the sex differences in constitutive autophagy in spinal cord and skeletal muscle tissue from wild type mice. To examine the influence of sex on autophagy, mRNA and proteins were extracted from male and female mice tissues. The expressions of microtubule-associated protein 1 light chain 3 (LC3) and sequestosome 1 (p62), markers to monitor autophagy, were analyzed at 40, 60, 90, and 120 days of age. We found significant sex differences in the expression of LC3 and p62 in both tissues at these ages. The results indicated that sex and tissue specific differences exist in constitutive autophagy. These data underlined the need to include both sexes in the experimental groups to minimize any sex bias. PMID:24719882
NASA Astrophysics Data System (ADS)
Strzerzynski, P.; Guillot, S.; Leloup, P. H.; Arnaud, N.; Vidal, O.; Ledru, P.; Courrioux, G.; Darmendrail, X.
2009-04-01
Understanding exhumation processes of high to ultra-high pressure (HP to UHP) terrains during plate convergence is a major challenge for the comprehension of plate convergence processes and mountain building. Contemporaneous contraction and extension coupled with erosion are frequently proposed to drive the exhumation process. In the internal alpine belt, HP and UHP metamorphism are recorded both in the Piemont oceanic unit and in the continental units such as the Internal Crystalline Massifs and the Briançonnais zone. In the western Alps, the consensus is to relate the top to NW then W directed D1 thrusting phase to nappe stacking and exhumation of the HP to UHP units within a subduction channel. Although there is an agreement on the occurrence of a top to the east D2 tectonic phase, its significance in terms of shortening or extensional deformation is controversial. On one hand, top to the east D2 shear zones and associated folds are interpreted as backthrusts or backfolds active during the Oligocene syn-collisional shortening phase, post-dating the exhumation of the HP units. On the other hand, D2 structures are interpreted as top the east normal faults that are active during the exhumation of the HP unit within a subduction channel. To decipher between these two different interpretations, we conducted a combined structural, petrological and geochronological study of the Modane-Aussois area in order to build a PTtD path of the Briançonnais zone. The current construction of a high velocity railway tunnel between the Maurienne and Susa valleys provides the opportunity to gather a large amount of geological data in the internal Western Alps and to extend surface observation at depth. We provide a structural analysis on ductile and brittle domains. New PT estimates are obtained using pseudosection and multiequilibra methods. Ar/Ar step heating on phengite provide time constraint on tectonic phases. Then, in light of our data and available literature, we focus on
[Women, gender, and the Constitution].
1993-12-01
Although all the constitutions of Latin America directly or indirectly acknowledge the juridical equality of the sexes, these patriarchal societies continue to maintain institutional power in male hands and to neutralize legal actions favoring women. International instruments such as the Convention on Elimination of All Forms of Discrimination Against Women, approved by the UN in 1979, have given a firmer basis to policies and actions to improve the status of women. Obstacles to full equality of Latin American women are rooted in economic and sociopolitical factors, but lack of true political will also plays a significant role. A number of new laws in the past several years as well as the new Constitution have improved the legal position of Colombian women. The new Constitution recognizes fundamental rights that may be claimed directly before a judge, and social, economic, and collective rights requiring legislative development. Article 43 of the new Constitution states that women will not be subjected to any form of discrimination. Another norm states that women will enjoy special assistance and protection before and after childbirth, in recognition of the social functions of maternity. Article 43 also states that women who are heads of households will receive special assistance, but the corresponding regulations have not yet been promulgated. The mechanism of tutelage has become an important recourse that has been used in several cases in which fundamental rights of women have been violated or threatened because of their sex. The order of tutelage has been used in cases of adolescents expelled from school for pregnancy and of abused wives, as well as to force recognition of the social and economic contributions of housework.
[Women, gender, and the Constitution].
1993-12-01
Although all the constitutions of Latin America directly or indirectly acknowledge the juridical equality of the sexes, these patriarchal societies continue to maintain institutional power in male hands and to neutralize legal actions favoring women. International instruments such as the Convention on Elimination of All Forms of Discrimination Against Women, approved by the UN in 1979, have given a firmer basis to policies and actions to improve the status of women. Obstacles to full equality of Latin American women are rooted in economic and sociopolitical factors, but lack of true political will also plays a significant role. A number of new laws in the past several years as well as the new Constitution have improved the legal position of Colombian women. The new Constitution recognizes fundamental rights that may be claimed directly before a judge, and social, economic, and collective rights requiring legislative development. Article 43 of the new Constitution states that women will not be subjected to any form of discrimination. Another norm states that women will enjoy special assistance and protection before and after childbirth, in recognition of the social functions of maternity. Article 43 also states that women who are heads of households will receive special assistance, but the corresponding regulations have not yet been promulgated. The mechanism of tutelage has become an important recourse that has been used in several cases in which fundamental rights of women have been violated or threatened because of their sex. The order of tutelage has been used in cases of adolescents expelled from school for pregnancy and of abused wives, as well as to force recognition of the social and economic contributions of housework. PMID:12287889
A constitutive function for the heat flux in short-fiber-reinforced composites
NASA Astrophysics Data System (ADS)
Herrmann, Heiko
2015-12-01
A constitutive function for heat flux in short-fiber-reinforced composites is developed. The fiber orientation distribution is considered using second-order orientation tensor; therefore, the constitutive function for the heat flux will depend on the orientation tensor. The resulting orthotropic equation is discussed also in the context of energy efficiency of buildings.
The Constitution: Perspectives on Contemporary American Democracy.
ERIC Educational Resources Information Center
Close Up Foundation, Arlington, VA.
Four articles expressing the views of nine prominent United States citizens about the Constitution provide a context for reflecting on the meaning of the Constitution in present-day America. In "Why Has the Constitution Endured So Long?" Don Edwards, chairman of the House Civil and Constitutional Rights Subcommittee, discusses why the Constitution…
Constitutive relations associated with the Mott-Smith distribution function
Nathenson, M.; Baganoff, D.
1973-01-01
It is shown that the distribution function assumed by Mott-Smith determines a unique relation between heat flux, stress, and fluid velocity given by q = (3/2)??u, i.e., it provides a constitutive relation for heat flux, and it also determines a simple expression for this ratio of third-order central moments Q = . These expressions allow the equation of transfer for c x2 to be cast in a form that yields a nonlinear constitutive relation for stress. The results obtained from the Mott-Smith ansatz are compared with the theory of Baganoff and Nathenson and results from a numerical solution of the Boltzmann equation for shock-wave structure obtained by Hicks and Yen.
Asymptotic-preserving Boltzmann model equations for binary gas mixture.
Liu, Sha; Liang, Yihua
2016-02-01
An improved system of Boltzmann model equations is developed for binary gas mixture. This system of model equations has a complete asymptotic preserving property that can strictly recover the Navier-Stokes equations in the continuum limit with the correct constitutive relations and the correct viscosity, thermal conduction, diffusion, and thermal diffusion coefficients. In this equation system, the self- and cross-collision terms in Boltzmann equations are replaced by single relaxation terms. In monocomponent case, this system of equations can be reduced to the commonly used Shakhov equation. The conservation property and the H theorem which are important for model equations are also satisfied by this system of model equations. PMID:26986408
Unborn children as constitutional persons.
Roden, Gregory J
2010-01-01
In Roe v. Wade, the state of Texas argued that "the fetus is a 'person' within the language and meaning of the Fourteenth Amendment." To which Justice Harry Blackmun responded, "If this suggestion of personhood is established, the appellant's case, of course, collapses, for the fetus' right to life would then be guaranteed specifically by the Amendment." However, Justice Blackmun then came to the conclusion "that the word 'person,' as used in the Fourteenth Amendment, does not include the unborn." In this article, it is argued that unborn children are indeed "persons" within the language and meaning of the Fourteenth and Fifth Amendments. As there is no constitutional text explicitly holding unborn children to be, or not to be, "persons," this argument will be based on the "historical understanding and practice, the structure of the Constitution, and thejurisprudence of [the Supreme] Court." Specifically, it is argued that the Constitution does not confer upon the federal government a specifically enumerated power to grant or deny "personhood" under the Fourteenth Amendment. Rather, the power to recognize or deny unborn children as the holders of rights and duties has been historically exercised by the states. The Roe opinion and other Supreme Court cases implicitly recognize this function of state sovereignty. The states did exercise this power and held unborn children to be persons under the property, tort, and criminal law of the several states at the time Roe was decided. As an effect of the unanimity of the states in holding unborn children to be persons under criminal, tort, and property law, the text of the Equal Protection Clause of the Fourteenth Amendment compels federal protection of unborn persons. Furthermore, to the extent Justice Blackmun examined the substantive law in these disciplines, his findings are clearly erroneous and as a whole amount to judicial error. Moreover, as a matter of procedure, according to the due process standards recognized in
Rate constitutive theories for ordered thermoviscoelastic fluids: polymers
NASA Astrophysics Data System (ADS)
Surana, K. S.; Nunez, D.; Reddy, J. N.; Romkes, A.
2014-03-01
law of thermodynamics provides no mechanism for deriving the constitutive theories for the deviatoric Cauchy stress tensor. In the development of the constitutive theories in Eulerian description, the covariant and contravariant convected coordinate systems and Jaumann measures are natural choices. Furthermore, the mathematical models for fluids require Eulerian description in which material point displacements are not measurable. This precludes the use of displacement gradients, i.e., strain measures, in the development of the constitutive theories. It is shown that compatible conjugate pairs of convected time derivatives of the deviatoric Cauchy stress and strain measures in co-, contravariant and Jaumann bases in conjunction with the theory of generators and invariants provide a general mathematical framework for the development of constitutive theories for ordered thermofluids in Eulerian description. This framework has a foundation based on the basic principles and axioms of continuum mechanics, but the resulting constitutive theories for the deviatoric Cauchy stress tensor must satisfy the condition of positive work expanded, a requirement resulting from the entropy inequality. The paper presents a general theory of constitutive equations for ordered thermoviscoelastic fluids which is then specialized to obtain commonly used constitutive equations for Maxwell, Giesekus and Oldroyd-B constitutive models in contra- and covariant bases and using Jaumann rates.
NASA Astrophysics Data System (ADS)
Viljamaa, Panu; Jacobs, J. Richard; Chris; JamesHyman; Halma, Matthew; EricNolan; Coxon, Paul
2014-07-01
In reply to a Physics World infographic (part of which is given above) about a study showing that Euler's equation was deemed most beautiful by a group of mathematicians who had been hooked up to a functional magnetic-resonance image (fMRI) machine while viewing mathematical expressions (14 May, http://ow.ly/xHUFi).
Nonlinear creep damage constitutive model for soft rocks
NASA Astrophysics Data System (ADS)
Liu, H. Z.; Xie, H. Q.; He, J. D.; Xiao, M. L.; Zhuo, L.
2016-06-01
In some existing nonlinear creep damage models, it may be less rigorous to directly introduce a damage variable into the creep equation when the damage variable of the viscous component is a function of time or strain. In this paper, we adopt the Kachanov creep damage rate and introduce a damage variable into a rheological differential constitutive equation to derive an analytical integral solution for the creep damage equation of the Bingham model. We also propose a new nonlinear viscous component which reflects nonlinear properties related to the axial stress of soft rock in the steady-state creep stage. Furthermore, we build an improved Nishihara model by using this new component in series with the correctional Nishihara damage model that describes the accelerating creep, and deduce the rheological constitutive relation of the improved model. Based on superposition principle, we obtain the damage creep equation for conditions of both uniaxial and triaxial compression stress, and study the method for determining the model parameters. Finally, this paper presents the laboratory test results performed on mica-quartz schist in parallel with, or vertical to the schistosity direction, and applies the improved Nishihara model to the parameter identification of mica-quartz schist. Using a comparative analysis with test data, results show that the improved model has a superior ability to reflect the creep properties of soft rock in the decelerating creep stage, the steady-state creep stage, and particularly within the accelerating creep stage, in comparison with the traditional Nishihara model.
Constitutive Modeling of Magnesium Alloy Sheets
Lee, M. G.; Piao, K.; Wagoner, R. H.; Lee, J. K.; Chung, K.; Kim, H. Y.
2007-05-17
Magnesium alloy sheets have unique mechanical properties: high in-plane anisotropy/asymmetry of yield stress and hardening response, which have not been thoroughly studied. The unusual mechanical behavior of magnesium alloys has been understood by the limited symmetry crystal structure of h.c.p metals and thus by deformation twinning. In this paper, the phenomenological continuum plasticity models considering the unusual plastic behavior of magnesium alloy sheet were developed for a finite element analysis. A new hardening law based on two-surface model was developed to consider the general stress-strain response of metal sheets such as Bauschinger effect, transient behavior and the unusual asymmetry. Three deformation modes observed during the continuous tension/compression tests were mathematically formulated with simplified relations between the state of deformation and their histories. In terms of the anisotropy and asymmetry of the initial yield stress, the Drucker-Prager's pressure dependent yield surface was modified to include the anisotropy of magnesium alloys. Also, characterization procedures of material parameters for the constitutive equations were presented and finally the correlation of simulation with measurements was performed to validate the proposed theory.
Linear superposition solutions to nonlinear wave equations
NASA Astrophysics Data System (ADS)
Liu, Yu
2012-11-01
The solutions to a linear wave equation can satisfy the principle of superposition, i.e., the linear superposition of two or more known solutions is still a solution of the linear wave equation. We show in this article that many nonlinear wave equations possess exact traveling wave solutions involving hyperbolic, triangle, and exponential functions, and the suitable linear combinations of these known solutions can also constitute linear superposition solutions to some nonlinear wave equations with special structural characteristics. The linear superposition solutions to the generalized KdV equation K(2,2,1), the Oliver water wave equation, and the k(n, n) equation are given. The structure characteristic of the nonlinear wave equations having linear superposition solutions is analyzed, and the reason why the solutions with the forms of hyperbolic, triangle, and exponential functions can form the linear superposition solutions is also discussed.
Written Constitution or None: Which Works Better?
ERIC Educational Resources Information Center
Cowen, Zelman
1987-01-01
Explores the differences between the U.S. Constitution and British constitutional law. Specifically examines the concept of the U.S. Bill of Rights in relation to the United Kingdom common law doctrine of parliamentary sovereignty. (BSR)
A possible generalization of the field-theoretical Hamilton's equations
Savchin, V.M. )
1988-11-01
The development of classical dynamics as well as many branches of physics shows that the solution or analysis of variety of problems can be greatly simplified if the basic equations admit an analytic representation in terms of Hamilton's equations. The author proposes a generalization of Hamilton's equations in field theory which is applicable to partial differential equations of physical relevance. It is shown that the equations constitute a conceivable basis for the generalization of the theory of contact transformations and of Poisson's method.
Theoretical Issues of the Constitutional Regulation Mechanism
ERIC Educational Resources Information Center
Zhussupova, Guldaray B.; Zhailyaubayev, Rassul T.; Ukin, Symbat K.; Shunayeva, Sylu M.; Nurmagambetov, Rachit G.
2016-01-01
The purpose of this research is to define the concept of "constitutional regulation mechanism." The definition of the concept of "constitutional regulation mechanism" will give jurists and legislators a theoretical framework for developing legal sciences, such as the constitutional law and the theory of state and law. The…
Antithetical Ethics: Kenneth Burke and the Constitution.
ERIC Educational Resources Information Center
Anderson, Virginia
1995-01-01
Shows how the textuality of the United States Constitution, the most venerable of classic democratic icons, might be exploited to nurture postmodern ethics. Shows how Kenneth Burke's reading of the Constitution accords with and augments the postmodern theories of J.-F. Lyotard and S. Jarratt. Discusses a postmodern Constitution and the…
About Our Constitution: 1787-1987.
ERIC Educational Resources Information Center
National Council for the Social Studies, Washington, DC.
Designed to assist elementary school teachers, these materials present a series of lessons about the United States Constitution. Ten lesson plans and appropriate work sheets are included for grades K-3. The topics covered include the age of the Constitution, a constitutional convention, elected representatives, majority rule, voting, law making,…
32 CFR 536.42 - Constitutional torts.
Code of Federal Regulations, 2013 CFR
2013-07-01
... National Defense Department of Defense (Continued) DEPARTMENT OF THE ARMY CLAIMS AND ACCOUNTS CLAIMS AGAINST THE UNITED STATES Investigation and Processing of Claims § 536.42 Constitutional torts. A claim for violation of the U.S. Constitution does not constitute a state tort and is not cognizable...
32 CFR 536.42 - Constitutional torts.
Code of Federal Regulations, 2014 CFR
2014-07-01
... National Defense Department of Defense (Continued) DEPARTMENT OF THE ARMY CLAIMS AND ACCOUNTS CLAIMS AGAINST THE UNITED STATES Investigation and Processing of Claims § 536.42 Constitutional torts. A claim for violation of the U.S. Constitution does not constitute a state tort and is not cognizable...
32 CFR 536.42 - Constitutional torts.
Code of Federal Regulations, 2012 CFR
2012-07-01
... National Defense Department of Defense (Continued) DEPARTMENT OF THE ARMY CLAIMS AND ACCOUNTS CLAIMS AGAINST THE UNITED STATES Investigation and Processing of Claims § 536.42 Constitutional torts. A claim for violation of the U.S. Constitution does not constitute a state tort and is not cognizable...
32 CFR 536.42 - Constitutional torts.
Code of Federal Regulations, 2011 CFR
2011-07-01
... National Defense Department of Defense (Continued) DEPARTMENT OF THE ARMY CLAIMS AND ACCOUNTS CLAIMS AGAINST THE UNITED STATES Investigation and Processing of Claims § 536.42 Constitutional torts. A claim for violation of the U.S. Constitution does not constitute a state tort and is not cognizable...
7 CFR 718.201 - Farm constitution.
Code of Federal Regulations, 2011 CFR
2011-01-01
... 7 Agriculture 7 2011-01-01 2011-01-01 false Farm constitution. 718.201 Section 718.201 Agriculture... Reconstitution of Farms, Allotments, Quotas, and Bases § 718.201 Farm constitution. (a) In order to implement... this section. The constitution and identification of land as a farm for the first time and...
7 CFR 718.201 - Farm constitution.
Code of Federal Regulations, 2014 CFR
2014-01-01
... 7 Agriculture 7 2014-01-01 2014-01-01 false Farm constitution. 718.201 Section 718.201 Agriculture... Reconstitution of Farms, Allotments, Quotas, and Bases § 718.201 Farm constitution. (a) In order to implement... this section. The constitution and identification of land as a farm for the first time and...
29 CFR 452.18 - Constitutional officers.
Code of Federal Regulations, 2012 CFR
2012-07-01
... officer refers to a person holding a position identified as an officer by the constitution and bylaws of... constitution identifies the holder of such a position as an officer. On the other hand, legislative representatives who are required to be elected by the constitution and bylaws of a labor organization are...
29 CFR 452.18 - Constitutional officers.
Code of Federal Regulations, 2014 CFR
2014-07-01
... officer refers to a person holding a position identified as an officer by the constitution and bylaws of... constitution identifies the holder of such a position as an officer. On the other hand, legislative representatives who are required to be elected by the constitution and bylaws of a labor organization are...
7 CFR 718.201 - Farm constitution.
Code of Federal Regulations, 2013 CFR
2013-01-01
... 7 Agriculture 7 2013-01-01 2013-01-01 false Farm constitution. 718.201 Section 718.201 Agriculture... Reconstitution of Farms, Allotments, Quotas, and Bases § 718.201 Farm constitution. (a) In order to implement... this section. The constitution and identification of land as a farm for the first time and...
29 CFR 452.18 - Constitutional officers.
Code of Federal Regulations, 2013 CFR
2013-07-01
... officer refers to a person holding a position identified as an officer by the constitution and bylaws of... constitution identifies the holder of such a position as an officer. On the other hand, legislative representatives who are required to be elected by the constitution and bylaws of a labor organization are...
7 CFR 718.201 - Farm constitution.
Code of Federal Regulations, 2012 CFR
2012-01-01
... 7 Agriculture 7 2012-01-01 2012-01-01 false Farm constitution. 718.201 Section 718.201 Agriculture... Reconstitution of Farms, Allotments, Quotas, and Bases § 718.201 Farm constitution. (a) In order to implement... this section. The constitution and identification of land as a farm for the first time and...
American Focus on World Constitutions. Teacher's Guide.
ERIC Educational Resources Information Center
Holmes, Stanley T., III
This curriculum project was designed to familiarize high school students with their own constitutional roots while gaining a better understanding of governmental systems developed by other nations. The project uses the U.S. Constitution as a baseline for analyzing the constitutions of other nations, and is intended to supplement courses in such…
DOE R&D Accomplishments Database
1998-09-21
In the late 1950s to early 1960s Rudolph A. Marcus developed a theory for treating the rates of outer-sphere electron-transfer reactions. Outer-sphere reactions are reactions in which an electron is transferred from a donor to an acceptor without any chemical bonds being made or broken. (Electron-transfer reactions in which bonds are made or broken are referred to as inner-sphere reactions.) Marcus derived several very useful expressions, one of which has come to be known as the Marcus cross-relation or, more simply, as the Marcus equation. It is widely used for correlating and predicting electron-transfer rates. For his contributions to the understanding of electron-transfer reactions, Marcus received the 1992 Nobel Prize in Chemistry. This paper discusses the development and use of the Marcus equation. Topics include self-exchange reactions; net electron-transfer reactions; Marcus cross-relation; and proton, hydride, atom and group transfers.
78 FR 39721 - Constitution Pipeline Company, LLC; Notice of Application
Federal Register 2010, 2011, 2012, 2013, 2014
2013-07-02
... Energy Regulatory Commission Constitution Pipeline Company, LLC; Notice of Application Take notice that on June 13, 2013, Constitution Pipeline Company, LLC (Constitution), having its principal place of...\\ Constitution further requests that the Commission grant Constitution a blanket certificate...
Code of Federal Regulations, 2011 CFR
2011-01-01
.... Constitution Day and Citizenship Day, Constitution Week, 2010 8562 Proclamation 8562 Presidential Documents Proclamations Proclamation 8562 of September 16, 2010 Proc. 8562 Constitution Day and Citizenship Day... the States, the Framers advanced our national journey. On Constitution Day and Citizenship Day,...
75 FR 57835 - Constitution Day and Citizenship Day, Constitution Week, 2010
Federal Register 2010, 2011, 2012, 2013, 2014
2010-09-22
... two hundred and thirty-fifth. (Presidential Sig.) [FR Doc. 2010-23898 Filed 9-21-10; 11:15 am] Billing... Proclamation 8562--Constitution Day and Citizenship Day, Constitution Week, 2010 Proclamation 8563--National... President ] Proclamation 8562 of September 16, 2010 Constitution Day and Citizenship Day, Constitution...
ERIC Educational Resources Information Center
Pallasch, Brian Thomas
This civic education resource packet is designed to provide teachers, community leaders, and other civic educators with an understanding of the differences between constitutional and non-constitutional governments. Six papers discussing the topic are included: "The Differences bewteen Constitutional and Non-Constitutional Governments" (John…
Constitutive modelling of single crystal and directionally solidified superalloys
NASA Technical Reports Server (NTRS)
Jordan, E. H.; Walker, K. P.
1986-01-01
The trend towards improved engine efficiency and durability places increasing demands on materials that operate in the hot section of the gas turbine engine. These demands are being met by new coatings and materials such as single crystal and directionally solidified nickel-base superalloys which have greater creep/fatigue resistance at elevated temperatures and reduced susceptibility to grain boundary creep, corrosion and oxidation than conventionally cast alloys. Work carried out as part of a research program aimed at the development of constitutive equations to describe the elevated temperature stress-strain-time behavior of single crystal and directionally solidified turbine blade superalloys is discussed. The program involves both development of suitable constitutive models and their verification through elevated temperature tension-torsion testing of single crystals of PWA 1480.
A Continuum Constitutive Model for Cohesionless Granular Flows
Daniel, Richard C.; Poloski, Adam P.; Saez, Avelino E.
2007-03-01
A constitutive model is developed to represent shear granular flows of cohesionless solids. The model is based on the postulate that the friction coefficient and the solids fraction in a moving granular material are exclusive functions of the inertial number, which represents the ratio of inertial to normal stress forces. The constitutive equation obtained has the same form as a multidimensional Bingham fluid model, albeit with apparent viscosity and yield stress that depend on the vertical normal stress. The model is applied to previously published experimental results dealing with shear flows of granular beds made up of cohesionless spherical particles. The first case analyzed corresponds to a granular bed moving on top of a rotating disk. The model captures the main trends of the velocity profiles with a single adjustable parameter. The second case is a conventional Couette flow, for which the model is capable of representing the velocity and solids fraction profiles measured experimentally.
Temperature Dependent Constitutive Modeling for Magnesium Alloy Sheet
Lee, Jong K.; Lee, June K.; Kim, Hyung S.; Kim, Heon Y.
2010-06-15
Magnesium alloys have been increasingly used in automotive and electronic industries because of their excellent strength to weight ratio and EMI shielding properties. However, magnesium alloys have low formability at room temperature due to their unique mechanical behavior (twinning and untwining), prompting for forming at an elevated temperature. In this study, a temperature dependent constitutive model for magnesium alloy (AZ31B) sheet is developed. A hardening law based on non linear kinematic hardening model is used to consider Bauschinger effect properly. Material parameters are determined from a series of uni-axial cyclic experiments (T-C-T or C-T-C) with the temperature ranging 150-250 deg. C. The influence of temperature on the constitutive equation is introduced by the material parameters assumed to be functions of temperature. Fitting process of the assumed model to measured data is presented and the results are compared.
Defining the criteria for identifying constitutional epimutations.
Sloane, Mathew A; Ward, Robyn L; Hesson, Luke B
2016-01-01
In the January 2016 issue of Clinical Epigenetics, Quiñonez-Silva et al. (Clin Epigenetics 8:1, 2016) described a possible constitutional epimutation of the RB1 gene as a cause of hereditary predisposition to retinoblastoma. The term constitutional epimutation describes an epigenetic aberration in normal tissues that predisposes to disease. The data presented by Quiñonez-Silva et al. are interesting, but further analysis is required to demonstrate a constitutional epimutation in this family. Here, we define the criteria and describe the experimental approach necessary to identify an epigenetic aberration as a constitutional epimutation. PMID:27096027
Testing of constitutive models in LAME.
Hammerand, Daniel Carl; Scherzinger, William Mark
2007-09-01
Constitutive models for computational solid mechanics codes are in LAME--the Library of Advanced Materials for Engineering. These models describe complex material behavior and are used in our finite deformation solid mechanics codes. To ensure the correct implementation of these models, regression tests have been created for constitutive models in LAME. A selection of these tests is documented here. Constitutive models are an important part of any solid mechanics code. If an analysis code is meant to provide accurate results, the constitutive models that describe the material behavior need to be implemented correctly. Ensuring the correct implementation of constitutive models is the goal of a testing procedure that is used with the Library of Advanced Materials for Engineering (LAME) (see [1] and [2]). A test suite for constitutive models can serve three purposes. First, the test problems provide the constitutive model developer a means to test the model implementation. This is an activity that is always done by any responsible constitutive model developer. Retaining the test problem in a repository where the problem can be run periodically is an excellent means of ensuring that the model continues to behave correctly. A second purpose of a test suite for constitutive models is that it gives application code developers confidence that the constitutive models work correctly. This is extremely important since any analyst that uses an application code for an engineering analysis will associate a constitutive model in LAME with the application code, not LAME. Therefore, ensuring the correct implementation of constitutive models is essential for application code teams. A third purpose of a constitutive model test suite is that it provides analysts with example problems that they can look at to understand the behavior of a specific model. Since the choice of a constitutive model, and the properties that are used in that model, have an enormous effect on the results of an
NASA Astrophysics Data System (ADS)
Whitney, Donna L.; Roger, Françoise; Teyssier, Christian; Rey, Patrice F.; Respaut, J.-P.
2015-11-01
In many orogens, high-pressure (HP) metamorphic rocks such as eclogite occur as lenses in quartzofeldspathic gneiss that equilibrated at much lower pressures. The pressure-temperature-time (P-T-t) history of eclogite relative to host gneiss provides information about mechanisms and timescales of exhumation of orogenic crust. The Montagne Noire of the southern Massif Central, France, is an eclogite-bearing gneiss (migmatite) dome located at the orogen-foreland transition of the Variscan belt. Results of our study show that it contains the youngest eclogite in the orogen, similar in age to migmatite and granite that crystallized under low-pressure conditions. P-T conditions for an exceptionally unaltered eclogite from the central Montagne Noire were estimated using a pseudosection supplemented by garnet-clinopyroxene and Zr-in-rutile thermometry. Results indicate peak P ∼ 1.4 GPa and T ∼ 725°C for Mg-rich garnet rim (50 mol% pyrope) + omphacite (36 mol% jadeite) + rutile + quartz. U-Pb geochronology (LA-ICP-MS) of 16 zoned zircon grains yielded ∼360 Ma (4 cores) and ∼315 Ma (12 rims and cores). Rare earth element abundances determined by LA-ICP-MS for dated zircon are consistent with crystallization of ∼315 Ma zircon under garnet-stable, plagioclase-unstable conditions that we interpret to indicate high pressure; in contrast, the ∼360 Ma zircon core corresponds to crystallization under lower pressure plagioclase-stable conditions. Based on garnet zoning and inclusion suites, rutile textures and Zr zoning, P-T results, and zircon petrochronology, we interpret the ∼315 Ma date as the age of eclogite-facies metamorphism that only slightly preceded dome formation and crystallization at 315-300 Ma. This age relation indicates that eclogite formation at high pressure and migmatite dome emplacement at low pressure were closely spaced in time. We propose that collapse-driven material transfer from the hot orogen to the cool foreland resulted in thickening of
Dorais, Michael J.; Wintsch, Robert P.; Kunk, Michael J.; Aleinikoff, John; Burton, William; Underdown, Christine; Kerwin, Charles M.
2012-01-01
We present new evidence for the assignment of the Neoproterozoic Massabesic Gneiss Complex of New Hampshire to the Gander terrane rather than the Avalon terrane. The majority of Avalonian (sensu stricto) igneous and meta-igneous rocks as defined in Maritime Canada have positive whole-rock ɛNd compared to more negative values for Gander rocks, although there is a region of overlap in ɛNd between the two terranes. Our samples from areas in Connecticut previously thought to be Avalonian and samples from the Willimantic dome have the same isotopic signatures as Maritime Canada Avalon. In contrast, samples from the Clinton dome of southern Connecticut plots exclusively in the Gander field. The majority of the orthogneiss samples from Lyme dome (coastal Connecticut), Pelham dome (central Massachusetts) and Massabesic Gneiss Complex also plot in the Gander field, with a few samples plotting in the overlap zone between Gander and Avalon. U-Pb age distributions of detrital zircon populations from quartzites from the Massabesic Gneiss Complex more closely approximate the data from the Lyme Dome rather than Avalon. Additionally, the similarity of the P-T-t path for the rocks of the Massabesic Gneiss Complex (established by thermobarometry and 40Ar/39Ar dating of amphibole, muscovite, biotite and K-feldspar) with that established in the Ganderian Lyme dome of southern Connecticut strengthens the assignment of these rocks to a single Gander block that docked to Laurentia during the Salinic Orogeny. The identification of Ganderian isotopic signatures for these rocks all of which show evidence for Alleghanian metamorphism, supports the hypothesis that Neoproterozoic Gander lower crustal rocks underlie southern New Hampshire, Massachusetts, and Connecticut, and that all rocks of the overlying Central Maine trough that largely escaped high-grade Alleghanian metamorphism are allochthonous. We suggest that during the Alleghanian, the docking of Gondwana caused Avalon to wedge into
The United States and the Indian Constitution.
ERIC Educational Resources Information Center
Weil, Jonathan S.
India, a huge land with the second largest population in the world, socially and economically poor, and culturally and linguistically diverse, became the largest democracy in the world on November 26, 1949 with the adoption of the Indian Constitution. The goals of that constitution are: (1) the achievement of national unity and stability; (2) the…
From Confederation to Constitution: 1781-1789.
ERIC Educational Resources Information Center
Urofsky, Melvin I.; Cox, Nancy
Students should achieve a higher level of understanding and appreciation of the evolving nature of the U.S. Constitution and its relevance to contemporary societal issues by studying historical documents from the period of time between the Articles of Confederation and the Constitution. This document begins with a history of that period and of the…
The Constitution in the Twentieth Century.
ERIC Educational Resources Information Center
Murphy, Paul L.
1987-01-01
Investigates the development of the United States Constitution in the twentieth century up to and including the Burger Court. Contends that interpreting the Constitution is an important issue of our times. Consequently argues that we should teach students about the development of this document. (RKM)
32 CFR 536.42 - Constitutional torts.
Code of Federal Regulations, 2010 CFR
2010-07-01
... 32 National Defense 3 2010-07-01 2010-07-01 true Constitutional torts. 536.42 Section 536.42 National Defense Department of Defense (Continued) DEPARTMENT OF THE ARMY CLAIMS AND ACCOUNTS CLAIMS AGAINST THE UNITED STATES Investigation and Processing of Claims § 536.42 Constitutional torts. A...
Liberty, Power, and the American Constitutional Heritage.
ERIC Educational Resources Information Center
Madison, James H.
The principles, values, and issues of our constitutional heritage that should be emphasized in citizenship education are based on the concepts of liberty and power. The Constitution is not a sacred icon formulated by immortals, but rather a changing and controversial framework guided by a diverse group of practical politicians, sensitive to their…
An Internet Guide to Teaching the Constitution
ERIC Educational Resources Information Center
Risinger, C. Frederick
2005-01-01
In 2004, Congress passed and President Bush signed legislation designating every September 17 as Constitution Day and suggesting that all schools teach about the Constitution on that day. There are innumerable websites, countless lesson plans and a multitude of other teaching resources on the topic. Teachers were inundated with brochures,…
Constitutive model for the dynamic response of a NiTi shape memory alloy
NASA Astrophysics Data System (ADS)
Shi, Xiaohong; Zeng, Xiangguo; Chen, Huayan
2016-07-01
In this paper, based on irreversible thermodynamic theory, the Helmholtz free energy function, was selected to deduce both the master equations and evolution equations of the constitutive model of a NiTi alloy under high strain. The Helmholtz free energy function contains the parameters of the reflecting phase transition and plastic property. The constitutive model for a NiTi alloy was implemented using a semi-implicit stress integration algorithm. Four successive stages can be differentiated and simulated: parent phase elasticity, martensitic phase transition, martensitic elasticity, and dislocation yield. The simulation results are in good agreement with the experimental results.
Division G Commission 35: Stellar Constitution
NASA Astrophysics Data System (ADS)
Limongi, Marco; Lattanzio, John C.; Charbonnel, Corinne; Dominguez, Inma; Isern, Jordi; Karakas, Amanda; Leitherer, Claus; Marconi, Marcella; Shaviv, Giora; van Loon, Jacco
2016-04-01
Commission 35 (C35), ``Stellar Constitution'', consists of members of the International Astronomical Union whose research spans many aspects of theoretical and observational stellar physics and it is mainly focused on the comprehension of the properties of stars, stellar populations and galaxies. The number of members of C35 increased progressively over the last ten years and currently C35 comprises about 400 members. C35 was part of Division IV (Stars) until 2014 and then became part of Division G (Stars and Stellar Physics), after the main IAU reorganisation in 2015. Four Working Groups have been created over the years under Division IV, initially, and Division G later: WG on Active B Stars, WG on Massive Stars, WG on Abundances in Red Giant and WG on Chemically Peculiar and Related Stars. In the last decade the Commission had 4 presidents, Wojciech Dziembowski (2003-2006), Francesca D'Antona (2006-2009), Corinne Charbonnel (2009-2012) and Marco Limongi (2012-2015), who were assisted by an Organizing Committee (OC), usually composed of about 10 members, all of them elected by the C35 members and holding their positions for three years. The C35 webpage (http://iau-c35.stsci.edu) has been designed and continuously maintained by Claus Leitherer from the Space Telescope Institute, who deserves our special thanks. In addition to the various general information on the Commission structure and activities, it contains links to various resources, of interest for the members, such as stellar models, evolutionary tracks and isochrones, synthetic stellar populations, stellar yields and input physics (equation of state, nuclear cross sections, opacity tables), provided by various groups. The main activity of the C35 OC is that of evaluating, ranking and eventually supporting the proposals for IAU sponsored meetings. In the last decade the Commission has supported several meetings focused on topics more or less relevant to C35. Since the primary aim of this document is to
Constructing constitutive relationships for seismic and aseismic fault slip
Beeler, N.M.
2009-01-01
For the purpose of modeling natural fault slip, a useful result from an experimental fault mechanics study would be a physically-based constitutive relation that well characterizes all the relevant observations. This report describes an approach for constructing such equations. Where possible the construction intends to identify or, at least, attribute physical processes and contact scale physics to the observations such that the resulting relations can be extrapolated in conditions and scale between the laboratory and the Earth. The approach is developed as an alternative but is based on Ruina (1983) and is illustrated initially by constructing a couple of relations from that study. In addition, two example constitutive relationships are constructed; these describe laboratory observations not well-modeled by Ruina's equations: the unexpected shear-induced weakening of silica-rich rocks at high slip speed (Goldsby and Tullis, 2002) and fault strength in the brittle ductile transition zone (Shimamoto, 1986). The examples, provided as illustration, may also be useful for quantitative modeling.
Large Deformation Constitutive Laws for Isotropic Thermoelastic Materials
Plohr, Bradley J.; Plohr, Jeeyeon N.
2012-07-25
We examine the approximations made in using Hooke's law as a constitutive relation for an isotropic thermoelastic material subjected to large deformation by calculating the stress evolution equation from the free energy. For a general thermoelastic material, we employ the volume-preserving part of the deformation gradient to facilitate volumetric/shear strain decompositions of the free energy, its first derivatives (the Cauchy stress and entropy), and its second derivatives (the specific heat, Grueneisen tensor, and elasticity tensor). Specializing to isotropic materials, we calculate these constitutive quantities more explicitly. For deformations with limited shear strain, but possibly large changes in volume, we show that the differential equations for the stress components involve new terms in addition to the traditional Hooke's law terms. These new terms are of the same order in the shear strain as the objective derivative terms needed for frame indifference; unless the latter terms are negligible, the former cannot be neglected. We also demonstrate that accounting for the new terms requires that the deformation gradient be included as a field variable
Code of Federal Regulations, 2010 CFR
2010-01-01
.... Constitution Day and Citizenship Day, Constitution Week, 2009 8418 Proclamation 8418 Presidential Documents Proclamations Proclamation 8418 of September 16, 2009 Proc. 8418 Constitution Day and Citizenship Day... citizenship, the Congress, by joint resolution of February 29, 1952 (36 U.S.C. 106), designated September...
77 FR 57981 - Constitution Day and Citizenship Day, Constitution Week, 2012
Federal Register 2010, 2011, 2012, 2013, 2014
2012-09-18
... of the United States of America the two hundred and thirty- seventh. (Presidential Sig.) [FR Doc... September 18, 2012 Part VI The President Proclamation 8862--Constitution Day and Citizenship Day... ] Proclamation 8862 of September 13, 2012 Constitution Day and Citizenship Day, Constitution Week, 2012 By...
Code of Federal Regulations, 2012 CFR
2012-01-01
.... Constitution Day and Citizenship Day, Constitution Week, 2011 8714 Proclamation 8714 Presidential Documents Proclamations Proclamation 8714 of September 16, 2011 Proc. 8714 Constitution Day and Citizenship Day... because they believed in what our country stands for. Every year, thousands of candidates for...
78 FR 57777 - Constitution Day and Citizenship Day, Constitution Week, 2013
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2013-09-19
.... (Presidential Sig.) [FR Doc. 2013-23014 Filed 9-18-13; 11:15 am] Billing code 3295-F3 ... September 19, 2013 Part IV The President Proclamation 9019--Constitution Day and Citizenship Day... September 16, 2013 Constitution Day and Citizenship Day, Constitution Week, 2013 By the President of...
Code of Federal Regulations, 2013 CFR
2013-01-01
.... Constitution Day and Citizenship Day, Constitution Week, 2012 8862 Proclamation 8862 Presidential Documents Proclamations Proclamation 8862 of September 13, 2012 Proc. 8862 Constitution Day and Citizenship Day... candidates for citizenship who will commemorate this day by joining our American family. For more than...
The Constitutive Modeling of Thin Films with Randon Material Wrinkles
NASA Technical Reports Server (NTRS)
Murphey, Thomas W.; Mikulas, Martin M.
2001-01-01
Material wrinkles drastically alter the structural constitutive properties of thin films. Normally linear elastic materials, when wrinkled, become highly nonlinear and initially inelastic. Stiffness' reduced by 99% and negative Poisson's ratios are typically observed. This paper presents an effective continuum constitutive model for the elastic effects of material wrinkles in thin films. The model considers general two-dimensional stress and strain states (simultaneous bi-axial and shear stress/strain) and neglects out of plane bending. The constitutive model is derived from a traditional mechanics analysis of an idealized physical model of random material wrinkles. Model parameters are the directly measurable wrinkle characteristics of amplitude and wavelength. For these reasons, the equations are mechanistic and deterministic. The model is compared with bi-axial tensile test data for wrinkled Kaptong(Registered Trademark) HN and is shown to deterministically predict strain as a function of stress with an average RMS error of 22%. On average, fitting the model to test data yields an RMS error of 1.2%
Shore, B.W.
1981-01-30
The equations of motion are discussed which describe time dependent population flows in an N-level system, reviewing the relationship between incoherent (rate) equations, coherent (Schrodinger) equations, and more general partially coherent (Bloch) equations. Approximations are discussed which replace the elaborate Bloch equations by simpler rate equations whose coefficients incorporate long-time consequences of coherence.
Equations For Designing Superconducting Transmission Lines
NASA Technical Reports Server (NTRS)
Antsos, Dimitrios
1992-01-01
Characteristics of microwave circuits predicted accurately. Equations for propagation of quasitransverse electric and magnetic (TEM) waves along thin films of high-critical-temperature superconductors constitute basis of mathematical model useful in design of coplanar-waveguide, microstrip, and stripline microwave circuits. Model incorporated into older commercial software for computer-aided design of microwave circuit.
Nonlinear acoustic wave equations with fractional loss operators.
Prieur, Fabrice; Holm, Sverre
2011-09-01
Fractional derivatives are well suited to describe wave propagation in complex media. When introduced in classical wave equations, they allow a modeling of attenuation and dispersion that better describes sound propagation in biological tissues. Traditional constitutive equations from solid mechanics and heat conduction are modified using fractional derivatives. They are used to derive a nonlinear wave equation which describes attenuation and dispersion laws that match observations. This wave equation is a generalization of the Westervelt equation, and also leads to a fractional version of the Khokhlov-Zabolotskaya-Kuznetsov and Burgers' equations.
Fractal ladder models and power law wave equations
Kelly, James F.; McGough, Robert J.
2009-01-01
The ultrasonic attenuation coefficient in mammalian tissue is approximated by a frequency-dependent power law for frequencies less than 100 MHz. To describe this power law behavior in soft tissue, a hierarchical fractal network model is proposed. The viscoelastic and self-similar properties of tissue are captured by a constitutive equation based on a lumped parameter infinite-ladder topology involving alternating springs and dashpots. In the low-frequency limit, this ladder network yields a stress-strain constitutive equation with a time-fractional derivative. By combining this constitutive equation with linearized conservation principles and an adiabatic equation of state, a fractional partial differential equation that describes power law attenuation is derived. The resulting attenuation coefficient is a power law with exponent ranging between 1 and 2, while the phase velocity is in agreement with the Kramers–Kronig relations. The fractal ladder model is compared to published attenuation coefficient data, thus providing equivalent lumped parameters. PMID:19813816
The Constitution and the Black Experiences
ERIC Educational Resources Information Center
Miles, E. W.
1973-01-01
A review of the constitutional promises to black people, early congressional efforts to fulfill these promises, early court cases construing the Fourteenth Amendment and the impact of these decisions along with their subsequent overruling. (Author/JB)
Toward a Turbulence Constitutive Relation for Rotating Flows
NASA Technical Reports Server (NTRS)
Ristorcelli, J. R.
1996-01-01
In rapidly rotating turbulent flows the largest scales of the motion are in approximate geostrophic balance. Single-point turbulence closures, in general, cannot attain a geostrophic balance. This article addresses and resolves the possibility of constitutive relation procedures for single-point second order closures for a specific class of rotating or stratified flows. Physical situations in which the geostrophic balance is attained are described. Closely related issues of frame-indifference, horizontal nondivergence, Taylor-Proudman theorem and two-dimensionality are, in the context of both the instantaneous and averaged equations, discussed. It is shown, in the absence of vortex stretching along the axis of rotation, that turbulence is frame-indifferent. A derivation and discussion of a geostrophic constraint which the prognostic equations for second-order statistics must satisfy for turbulence approaching a frame-indifferent limit is given. These flow situations, which include rotating and nonrotating stratified flows, are slowly evolving flows in which the constitutive relation procedures are useful. A nonlinear non-constant coefficient representation for the rapid-pressure strain covariance appearing in the Reynolds stress and heat flux equations consistent with the geostrophic balance is described. The rapid-pressure strain model coefficients are not constants determined by numerical optimization but are functions of the state of the turbulence as parameterized by the Reynolds stresses and the turbulent heat fluxes. The functions are valid for all states of the turbulence attaining their limiting values only when a limit state is achieved. These issues are relevant to strongly vortical flows as well as flows such as the planetary boundary layers, in which there is a transition from a three-dimensional shear driven turbulence to a geostrophic or horizontal turbulence.
NASA Astrophysics Data System (ADS)
Fisanov, V. V.
2013-02-01
Differential equations for the Beltrami electromagnetic monochromatic fields with external sources are presented in the vector and quaternion forms in two variants in which the isotropic chiral medium is described by the conventional and modified Drude-Born-Fedorov constitutive relations. The modified equations provide equivalence of the description of fields and their sources in comparison with other symmetric coupling systems.
South African court rejects country's new constitution.
1996-09-20
Fundamental principles designed to ensure that South Africa's new constitution upholds a wide range of individual rights and freedoms and establishes a responsive government with a balanced separation of powers, including recognition of the role of traditional tribal leadership, were adopted into the current interim constitution shortly before the 1994 free elections which brought Nelson Mandela and the African National Congress to power. In a judgement issued on September 6, 1996, South Africa's Constitutional Court rejected the country's new draft constitution, arguing that it failed to meet the standards of nine of the 34 principles established at the Kempton Park negotiations. The Constitutional Assembly is comprised of a joint meeting of the National Assembly and Senate. One of the court's major objections to the constitution concerned the proposed structure of rule, which was seen to give inadequate power to South Africa's nine provinces as compared with the national government. However, the bill of rights was almost entirely upheld. The bill would create a favorable environment for legalized abortion and guarantee a universal right of access to health care, including reproductive health services
An update on the constitutive relation of ligament tissues with the effects of collagen types.
Wan, Chao; Hao, Zhixiu; Tong, Lingying; Lin, Jianhao; Li, Zhichang; Wen, Shizhu
2015-10-01
The musculoskeletal ligament is a kind of multiscale composite material with collagen fibers embedded in a ground matrix. As the major constituent in ligaments to bear external loads, collagens are composed mainly of two collagen contents with different mechanical properties, i.e., types I and III collagen. The constitutive relation of ligaments plays a critical role in the stability and normal function of human joints. However, collagen types have not been distinguished in the previous constitutive relations. In this paper a constitutive relation for ligament tissues was modified based on the previous constitutive relation by considering the effects of collagen types. Both the collagen contents and the mechanical properties of sixteen ligament specimens from four cadaveric human knee joints were measured for determining their material coefficients in the constitutive relation. The mechanical behaviors of ligaments were obtained from both the uniaxial tensile and simple shear tests. A linear regression between joint kinematic results from in vitro and in silico experiments was made to validate the accuracy of this constitutive relation. The high correlation coefficient (R(2)=0.93) and significance (P<0.0001) of the regression equation revealed that this modified constitutive relation of ligaments was accurate to be used in studying joint biomechanics. Another finite element analysis with collagen contents changing demonstrated that the effect of variations in collagen ratios on both joint kinematics and ligament biomechanics could be simulated by this constitutive relation.
Lee, H.K.; Simunovic, S.
1999-09-01
A micromechanical damage constitutive model is presented to predict the overall elastoplastic behavior and damage evolution in random carbon fiber polymer matrix composites (RFPCs).To estimate the overall elastoplastic damage responses,an effective yield criterion is derived based on the ensemble-volume averaging process and first-order effects of eigenstrains due to the existence of spheroidal (prolate) fibers.The proposed effective yield criterion,to ether with the assumed overall associative plastic flow rule and hardening law, constitutes the analytical foundation for the estimation of effective elastoplastic behavior of ductile matrix composites.First,an effective elastoplastic constitutive dama e model for aligned fiber-reinforced composites is proposed.A micromechanical damage constitutive model for RFPCs is then developed.The average process over all orientations upon overning constitutive field equations and overall yield function for aligned fiber-reinforced composites i s performed to obtain the constitutive relations and effective yield function of RFPCs.The discrete numerical integration algorithms and the continuum tan ent operator are also presented to implement the proposed dama e constitutive model.The dama e constitutive model forms the basis for the pro ressive crushing in composite structures under impact loading.
The Bernoulli Equation in a Moving Reference Frame
ERIC Educational Resources Information Center
Mungan, Carl E.
2011-01-01
Unlike other standard equations in introductory classical mechanics, the Bernoulli equation is not Galilean invariant. The explanation is that, in a reference frame moving with respect to constrictions or obstacles, those surfaces do work on the fluid, constituting an extra term that needs to be included in the work-energy calculation. A…
Comparison of fractional wave equations for power law attenuation in ultrasound and elastography.
Holm, Sverre; Näsholm, Sven Peter
2014-04-01
A set of wave equations with fractional loss operators in time and space are analyzed. The fractional Szabo equation, the power law wave equation and the causal fractional Laplacian wave equation are all found to be low-frequency approximations of the fractional Kelvin-Voigt wave equation and the more general fractional Zener wave equation. The latter two equations are based on fractional constitutive equations, whereas the former wave equations have been derived from the desire to model power law attenuation in applications like medical ultrasound. This has consequences for use in modeling and simulation, especially for applications that do not satisfy the low-frequency approximation, such as shear wave elastography. In such applications, the wave equations based on constitutive equations are the viable ones.
Health care law versus constitutional law.
Hall, Mark A
2013-04-01
National Federation of Independent Business v. Sebelius, the Supreme Court's ruling on the Patient Protection and Affordable Care Act, is a landmark decision - both for constitutional law and for health care law and policy. Others will study its implications for constitutional limits on a range of federal powers beyond health care. This article considers to what extent the decision is also about health care law, properly conceived. Under one view, health care law is the subdiscipline that inquires how courts and government actors take account of the special features of medicine that make legal or policy issues especially problematic - rather than regarding health care delivery and finance more generically, like most any other economic or social enterprise. Viewed this way, the opinions from the Court's conservative justices are mainly about general constitutional law principles. In contrast, Justice Ruth Bader Ginsburg's dissenting opinion for the four more liberal justices is just as much about health care law as it is about constitutional law. Her opinion gives detailed attention to the unique features of health care finance and delivery in order to inform her analysis of constitutional precedents and principles. Thus, the Court's multiple opinions give a vivid depiction of the compelling contrasts between communal versus individualistic conceptions of caring for those in need, and between health care and health insurance as ordinary commodities versus ones that merit special economic, social, and legal status.
NASA Technical Reports Server (NTRS)
Hamrock, B. J.; Dowson, D.
1981-01-01
Lubricants, usually Newtonian fluids, are assumed to experience laminar flow. The basic equations used to describe the flow are the Navier-Stokes equation of motion. The study of hydrodynamic lubrication is, from a mathematical standpoint, the application of a reduced form of these Navier-Stokes equations in association with the continuity equation. The Reynolds equation can also be derived from first principles, provided of course that the same basic assumptions are adopted in each case. Both methods are used in deriving the Reynolds equation, and the assumptions inherent in reducing the Navier-Stokes equations are specified. Because the Reynolds equation contains viscosity and density terms and these properties depend on temperature and pressure, it is often necessary to couple the Reynolds with energy equation. The lubricant properties and the energy equation are presented. Film thickness, a parameter of the Reynolds equation, is a function of the elastic behavior of the bearing surface. The governing elasticity equation is therefore presented.
General constitutive model for supercooled liquids: anomalous transverse wave propagation.
Mizuno, Hideyuki; Yamamoto, Ryoichi
2013-03-01
A transverse acoustic wave propagates through supercooled liquids in an anomalous manner: for a macroscopic wave number k, the wave propagates long distances, as in elastic solids, whereas it attenuates rapidly for a mesoscopic to microscopic wave number k, as in viscous liquids. In this work, we theoretically describe this anomalous wave propagation using the hydrodynamics of the two-mode Maxwell constitutive model, which were determined independently from the mechanical properties under oscillatory shear strains. To ensure that the Maxwell model can be applied down to a microscopic length scale, we extended it to a k-dependent equation, taking into account the recently reported k dependences of the shear viscosity and modulus [A. Furukawa and H. Tanaka, Phys. Rev. Lett. 103, 135703 (2009); A. Furukawa H. Tanaka Phys. Rev. E 84, 061503 (2011)]. The anomalous wave propagation in supercooled liquids can also be understood in terms of a linear coupling of many independent normal modes, as in amorphous solids. PMID:23496725
Constitutive modeling and computational implementation for finite strain plasticity
NASA Technical Reports Server (NTRS)
Reed, K. W.; Atluri, S. N.
1985-01-01
This paper describes a simple alternate approach to the difficult problem of modeling material behavior. Starting from a general representation for a rate-tpe constitutive equation, it is shown by example how sets of test data may be used to derive restrictions on the scalar functions appearing in the representation. It is not possible to determine these functions from experimental data, but the aforementioned restrictions serve as a guide in their eventual definition. The implications are examined for hypo-elastic, isotropically hardening plastic, and kinematically hardening plastic materials. A simple model for the evolution of the 'back-stress,' in a kinematic-hardening plasticity theory, that is entirely analogous to a hypoelastic stress-strain relation is postulated and examined in detail in modeling finitely plastic tension-torsion test. The implementation of rate-type material models in finite element algorithms is also discussed.
Code of Federal Regulations, 2014 CFR
2014-01-01
..., Constitution Week, 2013By the President of the United States of America A Proclamation In May of 1787... each year as “Constitution Week.” NOW, THEREFORE, I, BARACK OBAMA, President of the United States of... September, in the year of our Lord two thousand thirteen, and of the Independence of the......
Celebrating the Constitution: A Bicentennial Retrospective.
ERIC Educational Resources Information Center
Walch, Timothy G., Ed.
1988-01-01
This commemorative document was published to celebrate the Bicentennial of the signing of the U.S. Constitution and to pay tribute to the bicentennial celebration efforts of the U.S. National Archives and Records Administration staff. The included articles are: (1) "Introduction: A Celebration at the National Archives" (F. Burke); (2) "The Odyssey…
James Madison and the Constitutional Convention.
ERIC Educational Resources Information Center
Scanlon, Thomas M.
1987-01-01
Part 1 of this three-part article traces James Madison's life and focuses primarily on those events that prepared him for leadership in the U.S. Constitutional Convention of 1787. It describes his early love of learning, education, and public service efforts. Part 2 chronicles Madison's devotion to study and preparation prior to the Constitutional…
Crushed-salt constitutive model update
Callahan, G.D.; Loken, M.C.; Mellegard, K.D.
1998-01-01
Modifications to the constitutive model used to describe the deformation of crushed salt are presented in this report. Two mechanisms--dislocation creep and grain boundary diffusional pressure solutioning--defined previously but used separately are combined to form the basis for the constitutive model governing the deformation of crushed salt. The constitutive model is generalized to represent three-dimensional states of stress. New creep consolidation tests are combined with an existing database that includes hydrostatic consolidation and shear consolidation tests conducted on Waste Isolation Pilot Plant and southeastern New Mexico salt to determine material parameters for the constitutive model. Nonlinear least-squares model fitting to data from the shear consolidation tests and a combination of the shear and hydrostatic consolidation tests produced two sets of material parameter values for the model. The change in material parameter values from test group to test group indicates the empirical nature of the model but demonstrates improvement over earlier work with the previous models. Key improvements are the ability to capture lateral strain reversal and better resolve parameter values. To demonstrate the predictive capability of the model, each parameter value set was used to predict each of the tests in the database. Based on the fitting statistics and the ability of the model to predict the test data, the model appears to capture the creep consolidation behavior of crushed salt quite well.
Censorship of Obscenity: The Developing Constitutional Standards.
ERIC Educational Resources Information Center
Lockhart, William B.; McClure, Robert C.
1960-01-01
To demonstrate that substantial protection has been given to published material dealing with sex, an analysis of the constitutional criteria governing recent Supreme Court decisions in the area of obscenity censorship is presented. It is found that the Supreme Court uses "hard core pornography" as the foundation of a "constant" concept of…
Student Perspectives on Behaviors That Constitute Cheating
ERIC Educational Resources Information Center
Higbee, Jeanne L.; Schultz, Jennifer L.; Sanford, Thomas
2011-01-01
A previous study conducted a decade ago determined that there can be considerable disagreement--not only between students and faculty, but also among students and among faculty--regarding behaviors that constitute cheating. This article reports the results of a research study that replicated the student survey administered for the previous study,…
School Choice and State Constitutions' Religion Clauses
ERIC Educational Resources Information Center
Komer, Richard D.
2009-01-01
After the U.S. Supreme Court's decision in "Zelman v. Simmons-Harris," only state religion clauses represent a potential constitutional bar to the inclusion of religious options in properly designed school choice programs. The two most significant are compelled support clauses and Blaine Amendments. Both are frequently misinterpreted by state…
Rapping the 27 Amendments to the Constitution
ERIC Educational Resources Information Center
Knaresborough, Adam
2009-01-01
Early in the year, the students of history and government at Mountain View High School in Stafford, Virginia, began to devise hand motions to help memorize the 27 amendments to the Constitution for government class. Three students in the school who are interested in hip hop music then suggested composing a rap song about the topic. Working with…
The Search for Constitutional School Choice.
ERIC Educational Resources Information Center
Bauknight, Suzanne H.
1998-01-01
Addresses the constitutionality of tuition-voucher programs that provide access to private, parochial schools. Surveys Establishment Clause jurisprudence of the United States Supreme Court. Examines the Cleveland, Ohio, and Milwaukee, Wisconsin, tuition-voucher programs, currently being litigated in the respective state courts, in an attempt to…
7 CFR 718.201 - Farm constitution.
Code of Federal Regulations, 2010 CFR
2010-01-01
... land after the last constitution or reconstitution and as a result of such change the farm does not... agency programs and monitor farmer compliance with regulations, the agency must have records on what land is being farmed by a particular producer. This is accomplished by a determination of what land...
ERIC Educational Resources Information Center
Blakley, G. R.
1982-01-01
Reviews mathematical techniques for solving systems of homogeneous linear equations and demonstrates that the algebraic method of balancing chemical equations is a matter of solving a system of homogeneous linear equations. FORTRAN programs using this matrix method to chemical equation balancing are available from the author. (JN)
Numerical tests of constitutive laws for dense granular flows.
Lois, Gregg; Lemaître, Anaël; Carlson, Jean M
2005-11-01
We numerically and theoretically study the macroscopic properties of dense, sheared granular materials. In this process we first consider an invariance in Newton's equations, explain how it leads to Bagnold's scaling, and discuss how it relates to the dynamics of granular temperature. Next we implement numerical simulations of granular materials in two different geometries--simple shear and flow down an incline--and show that measurements can be extrapolated from one geometry to the other. Then we observe nonaffine rearrangements of clusters of grains in response to shear strain and show that fundamental observations, which served as a basis for the shear transformation zone (STZ) theory of amorphous solids [M. L. Falk and J. S. Langer, Phys. Rev. E. 57, 7192 (1998); M.R.S. Bull 25, 40 (2000)], can be reproduced in granular materials. Finally we present constitutive equations for granular materials as proposed by Lemaître [Phys. Rev. Lett. 89, 064303 (2002)], based on the dynamics of granular temperature and STZ theory, and show that they match remarkably well with our numerical data from both geometries.
Kinetic energy equations for the average-passage equation system
NASA Technical Reports Server (NTRS)
Johnson, Richard W.; Adamczyk, John J.
1989-01-01
Important kinetic energy equations derived from the average-passage equation sets are documented, with a view to their interrelationships. These kinetic equations may be used for closing the average-passage equations. The turbulent kinetic energy transport equation used is formed by subtracting the mean kinetic energy equation from the averaged total instantaneous kinetic energy equation. The aperiodic kinetic energy equation, averaged steady kinetic energy equation, averaged unsteady kinetic energy equation, and periodic kinetic energy equation, are also treated.
Turbulence constitutive modeling of the square root of the Reynolds stress.
Ariki, Taketo
2015-11-01
A methodology for turbulence constitutive modeling is discussed on the basis of the square-root tensor of the Reynolds stress. The present methodology can satisfy the realizability condition for the Reynolds stress proposed by Schumann [Phys. Fluids 20, 721 (1977)] in a more general manner than the conventional methodologies. The definition and uniqueness of the square-root tensor have been discussed, and its boundary condition has been properly obtained consistently with that of the Reynolds stress. Examples of possible constitutive models of both tensor-expansion and transport-equation types have been proposed. PMID:26651782
Turbulence constitutive modeling of the square root of the Reynolds stress
NASA Astrophysics Data System (ADS)
Ariki, Taketo
2015-11-01
A methodology for turbulence constitutive modeling is discussed on the basis of the square-root tensor of the Reynolds stress. The present methodology can satisfy the realizability condition for the Reynolds stress proposed by Schumann [Phys. Fluids 20, 721 (1977)], 10.1063/1.861942 in a more general manner than the conventional methodologies. The definition and uniqueness of the square-root tensor have been discussed, and its boundary condition has been properly obtained consistently with that of the Reynolds stress. Examples of possible constitutive models of both tensor-expansion and transport-equation types have been proposed.
Constitutive equations for multiphase TRIP steels at high rates of strain
NASA Astrophysics Data System (ADS)
van Slycken, J.; Verleysen, P.; Degrieck, J.; Bouquerel, J.
2006-08-01
Multiphase TRansformation Induced Plasticity (TRIP) steels show an excellent combination of high strength and high strain values, making them ideally suited for use in vehicle body structures. A complex synergy of three different phases (ferrite, bainite and austenite) on the one hand, and the meta-stable character of the austenite on the other hand, give the material indeed a high energy absorption potential. The knowledge and understanding of the dynamic behaviour of these sheet steels is essential to investigate the impact-dynamic characteristics of the structures. Therefore split Hopkinson tensile tests are performed in a strain rate range of 500 to 2000 s-1. Three TRIP steel grades with a different Al and Si content were studied. The experimental results show that these steels preserve their excellent shock-absorbing properties in dynamic conditions. The typical high strain rate loading conditions and the complex behaviour of TRIP steels offer a unique investigation opportunity. This behaviour can be described with phenomenological material models that can be used for numerical simulations of car crashes. The Johnson-Cook model, a frequently used model in finite element codes, is well-suited to describe the dynamic behaviour of the investigated TRIP steels. This model is compared to the Rusinek-Klepaczko model.
Constitutive equation of friction based on the subloading-surface concept
Ueno, Masami; Kuwayama, Takuya; Suzuki, Noriyuki; Yonemura, Shigeru; Yoshikawa, Nobuo
2016-01-01
The subloading-friction model is capable of describing static friction, the smooth transition from static to kinetic friction and the recovery to static friction after sliding stops or sliding velocity decreases. This causes a negative rate sensitivity (i.e. a decrease in friction resistance with increasing sliding velocity). A generalized subloading-friction model is formulated in this article by incorporating the concept of overstress for viscoplastic sliding velocity into the subloading-friction model to describe not only negative rate sensitivity but also positive rate sensitivity (i.e. an increase in friction resistance with increasing sliding velocity) at a general sliding velocity ranging from quasi-static to impact sliding. The validity of the model is verified by numerical experiments and comparisons with test data obtained from friction tests using a lubricated steel specimen. PMID:27493570
Flow effects of blood constitutive equations in 3D models of vascular anomalies
NASA Astrophysics Data System (ADS)
Neofytou, Panagiotis; Tsangaris, Sokrates
2006-06-01
The effects of different blood rheological models are investigated numerically utilizing two three- dimensional (3D) models of vascular anomalies, namely a stenosis and an abdominal aortic aneurysm model. The employed CFD code incorporates the SIMPLE scheme in conjunction with the finite-volume method with collocated arrangement of variables. The approximation of the convection terms is carried out using the QUICK differencing scheme, whereas the code enables also multi-block computations, which are useful in order to cope with the two-block grid structure of the current computational domain. Three non-Newtonian models are employed, namely the Casson, Power-Law and Quemada models, which have been introduced in the past for modelling the rheological behaviour of blood and cover both the viscous as well as the two-phase character of blood. In view of the haemodynamical mechanisms related to abnormalities in the vascular network and the role of the wall shear stress in initiating and further developing of arterial diseases, the present study focuses on the 3D flow field and in particular on the distribution as well as on both low and high values of the wall shear stress in the vicinity of the anomaly. Finally, a comparison is made between the effects of each rheological model on the aforementioned parameters. Results show marked differences between simulating blood as Newtonian and non-Newtonian fluid and furthermore the Power-Law model exhibits different behaviour in all cases compared to the other models whereas Quemada and Casson models exhibit similar behaviour in the case of the stenosis but different behaviour in the case of the aneurysm.
In quest of constitutional principles of "neurolaw".
Pizzetti, Federico Gustavo
2011-01-01
The growing use of brain imaging technology and the developing of cognitive neuroscience pose unaccustomed challenges to legal systems. Until now, the fields of Law much affected are the civil and criminal law and procedure, but the constitutional dimension of "neurolaw" cannot be easily underestimated. As the capacity to investigate and to trace brain mechanisms and functional neural activities increases, it becomes urgent the recognition and definition of the unalienable rights and fundamental values in respect of this new techno-scientific power, that must be protected and safeguard at "constitutional level" of norms such as: human dignity, personal identity, authenticity and the pursuit of individual "happiness". As the same as for the law regulating research and experimentation on human genome adopted in the past years, one may also argue if the above mentioned fundamental principles of "neurolaw" must be fixed and disciplined also at European and International level. PMID:23057208
Constitutive Modeling of Crosslinked Nanotube Materials
NASA Technical Reports Server (NTRS)
Odegard, G. M.; Frankland, S. J. V.; Herzog, M. N.; Gates, T. S.; Fay, C. C.
2004-01-01
A non-linear, continuum-based constitutive model is developed for carbon nanotube materials in which bundles of aligned carbon nanotubes have varying amounts of crosslinks between the nanotubes. The model accounts for the non-linear elastic constitutive behavior of the material in terms of strain, and is developed using a thermodynamic energy approach. The model is used to examine the effect of the crosslinking on the overall mechanical properties of variations of the crosslinked carbon nanotube material with varying degrees of crosslinking. It is shown that the presence of the crosslinks has significant effects on the mechanical properties of the carbon nanotube materials. An increase in the transverse shear properties is observed when the nanotubes are crosslinked. However, this increase is accompanied by a decrease in axial mechanical properties of the nanotube material upon crosslinking.
In quest of constitutional principles of "neurolaw".
Pizzetti, Federico Gustavo
2011-01-01
The growing use of brain imaging technology and the developing of cognitive neuroscience pose unaccustomed challenges to legal systems. Until now, the fields of Law much affected are the civil and criminal law and procedure, but the constitutional dimension of "neurolaw" cannot be easily underestimated. As the capacity to investigate and to trace brain mechanisms and functional neural activities increases, it becomes urgent the recognition and definition of the unalienable rights and fundamental values in respect of this new techno-scientific power, that must be protected and safeguard at "constitutional level" of norms such as: human dignity, personal identity, authenticity and the pursuit of individual "happiness". As the same as for the law regulating research and experimentation on human genome adopted in the past years, one may also argue if the above mentioned fundamental principles of "neurolaw" must be fixed and disciplined also at European and International level.
Association of Sasang Constitutional Type with Sarcopenia
Lee, Seung Ku; Yoon, Dae Wui; Choi, Kyung-Mee; Lee, Si Woo; Kim, Jong Yeol; Kim, Jin Kwan; Shin, Chol
2015-01-01
Sasang constitutional medicine (SCM) is a unique Korean traditional medicine that classifies human beings as four distinct types named Sasang constitutional types (SCTs), based on physiologic, physical, and psychological traits. Accumulating evidence has demonstrated that specific constitutional types are associated with chronic diseases, but no study has investigated the relationship between SCTs and sarcopenia. The aim of this study was to examine the association in a large population-based study. Data from 1,204 participants who completed questionnaires for life style, anthropometric evaluation, and biochemical analysis were analyzed. Classification of the SCTs was done using an integrated diagnostic method. Sarcopenia was defined as appendicular skeletal muscle mass/height2 less than one standard deviation below the gender-specific normal mean of a younger group. Dual-energy X-ray absorptiometry was used to assess whole body composition. The prevalence of sarcopenia was 8.6% in the Tae-eum (TE) type, 44.7% in the So-eum (SE) type, and 20.7% in the So-yang (SY) type. Multivariate analysis revealed that the SE and SY types had 9.22 (5.06–16.81; P < 0.0001) and 2.90 (1.76–4.76; P < 0.0001) greater odds of sarcopenia compared to the TE type, respectively. Our results show that the SE and SY types are significantly associated with increased prevalence of sarcopenia. PMID:26649062
A constitutive theory for rigid polyurethane foam
Neilsen, M.K.; Krieg, R.D.; Schreyer, H.L.
1992-12-31
Rigid, closed-cell, polyurethane foam consists of interconnected polyurethane plates which form cells. When this foam is compressed, it exhibits an initial elastic regime which is followed by a plateau regime in which the load required to compress the foam remains nearly constant. In the plateau regime, cell walls are damaged and large permanent volume changes are generated. As additional load is applied, cell walls are compressed against neighboring cell walls, and the stiffness of the foam increases and approaches a value equal to that of solid polyurethane. When the foam is loaded in tension, the cell walls are damaged and the foam fractures. A constitutive theory for rigid polyurethane foam has been developed. This theory is based on a decomposition of the foam into two parts: a skeleton and a nonlinear elastic continuum in parallel. The skeleton accounts for the foam behavior in the elastic and plateau regimes and is described using a coupled plasticity with continuum damage theory. The nonlinear elastic continuum accounts for the lock-up of the foam due to internal gas pressure and cell wall interactions. This new constitutive theory has been implemented in both static and dynamic finite element codes. Numerical simulations performed using the new constitutive theory are presented.
Implicit constitutive relations for nonlinear magnetoelastic bodies
Bustamante, R.; Rajagopal, K. R.
2015-01-01
Implicit constitutive relations that characterize the response of elastic bodies have greatly enhanced the arsenal available at the disposal of the analyst working in the field of elasticity. This class of models were recently extended to describe electroelastic bodies by the present authors. In this paper, we extend the development of implicit constitutive relations to describe the behaviour of elastic bodies that respond to magnetic stimuli. The models that are developed provide a rational way to describe phenomena that have hitherto not been adequately described by the classical models that are in place. After developing implicit constitutive relations for magnetoelastic bodies undergoing large deformations, we consider the linearization of the models within the context of small displacement gradients. We then use the linearized model to describe experimentally observed phenomena which the classical linearized magnetoelastic models are incapable of doing. We also solve several boundary value problems within the context of the models that are developed: extension and shear of a slab, and radial inflation and extension of a cylinder. PMID:25792968
A constitutive law for degrading bioresorbable polymers.
Samami, Hassan; Pan, Jingzhe
2016-06-01
This paper presents a constitutive law that predicts the changes in elastic moduli, Poisson's ratio and ultimate tensile strength of bioresorbable polymers due to biodegradation. During biodegradation, long polymer chains are cleaved by hydrolysis reaction. For semi-crystalline polymers, the chain scissions also lead to crystallisation. Treating each scission as a cavity and each new crystal as a solid inclusion, a degrading semi-crystalline polymer can be modelled as a continuum solid containing randomly distributed cavities and crystal inclusions. The effective elastic properties of a degrading polymer are calculated using existing theories for such solid and the tensile strength of the degrading polymer is predicted using scaling relations that were developed for porous materials. The theoretical model for elastic properties and the scaling law for strength form a complete constitutive relation for the degrading polymers. It is shown that the constitutive law can capture the trend of the experimental data in the literature for a range of biodegradable polymers fairly well. PMID:26971070
The Economics of the U.S. Constitution.
ERIC Educational Resources Information Center
Schug, Mark C., Ed.
1986-01-01
In conjunction with the United States Constitution's Bicentennial, this issue is devoted to the contributions the Constitution has made in shaping the U.S. economic system. The main article, "The Economics of the Constitution," provides important insights on how the Constitution influences the economic system through answers to the following…
Power: Constitutional Update. Bar/School Partnership Programs Series.
ERIC Educational Resources Information Center
American Bar Association, Chicago, IL. Special Committee on Youth Education for Citizenship.
The fourth in a special series of handbooks dealing with constitutional themes, this document looks at power in the context of the U.S. Constitution. "The Constitution's Prescription for Freedom" (L. Peach) examines the separation of powers provided for in the Constitution. "The Concept of Power" (C. Roach) is a series of strategies, some using…
29 CFR 402.1 - Labor organization constitution and bylaws.
Code of Federal Regulations, 2010 CFR
2010-07-01
... 29 Labor 2 2010-07-01 2010-07-01 false Labor organization constitution and bylaws. 402.1 Section... constitution and bylaws. Every labor organization shall adopt a constitution and bylaws consistent with the... a constitution and bylaws which it has previously adopted and under which it is operating when...
29 CFR 402.1 - Labor organization constitution and bylaws.
Code of Federal Regulations, 2012 CFR
2012-07-01
... 29 Labor 2 2012-07-01 2012-07-01 false Labor organization constitution and bylaws. 402.1 Section... constitution and bylaws. Every labor organization shall adopt a constitution and bylaws consistent with the... a constitution and bylaws which it has previously adopted and under which it is operating when...
29 CFR 402.1 - Labor organization constitution and bylaws.
Code of Federal Regulations, 2014 CFR
2014-07-01
... 29 Labor 2 2014-07-01 2014-07-01 false Labor organization constitution and bylaws. 402.1 Section... constitution and bylaws. Every labor organization shall adopt a constitution and bylaws consistent with the... a constitution and bylaws which it has previously adopted and under which it is operating when...
29 CFR 402.1 - Labor organization constitution and bylaws.
Code of Federal Regulations, 2013 CFR
2013-07-01
... 29 Labor 2 2013-07-01 2013-07-01 false Labor organization constitution and bylaws. 402.1 Section... constitution and bylaws. Every labor organization shall adopt a constitution and bylaws consistent with the... a constitution and bylaws which it has previously adopted and under which it is operating when...
29 CFR 402.1 - Labor organization constitution and bylaws.
Code of Federal Regulations, 2011 CFR
2011-07-01
... 29 Labor 2 2011-07-01 2011-07-01 false Labor organization constitution and bylaws. 402.1 Section... constitution and bylaws. Every labor organization shall adopt a constitution and bylaws consistent with the... a constitution and bylaws which it has previously adopted and under which it is operating when...
Reflections on Chemical Equations.
ERIC Educational Resources Information Center
Gorman, Mel
1981-01-01
The issue of how much emphasis balancing chemical equations should have in an introductory chemistry course is discussed. The current heavy emphasis on finishing such equations is viewed as misplaced. (MP)
Interpretation of Bernoulli's Equation.
ERIC Educational Resources Information Center
Bauman, Robert P.; Schwaneberg, Rolf
1994-01-01
Discusses Bernoulli's equation with regards to: horizontal flow of incompressible fluids, change of height of incompressible fluids, gases, liquids and gases, and viscous fluids. Provides an interpretation, properties, terminology, and applications of Bernoulli's equation. (MVL)
Formulation of Statistical Equation of Motion of Blood
Lew, H. S.
1969-01-01
A general form of the statistical equation of motion of the blood is derived by averaging the motion of individual elements of the blood over a small volume in space. This equation can be transformed into an explicit form to find the constitutive equations of the blood provided the detailed motion of the plasma in some neighborhood of a suspended particle is known. As a demonstration of such transformation, the general form of the statistical equation of motion is applied to the suspension of sphere with a very low concentration to find the effective viscosity. PMID:5764231
NASA Technical Reports Server (NTRS)
Valanis, K. C.; Lee, C. F.
1983-01-01
A single phenomenological constitutive equation is derived theoretically from first principles and applied to aluminum, tin and lead. The theory is based on deformation kinetics of steady creep in which the fundamental mechanism is atomic transport over potential barriers whose conformation is distorted by the application of a stress field. The form of the functional dependence of barrier distortion and stress over the entire temperature range is found to be a sigmoidal curve which tends to straight lines of a unit slope in the small and high stress regions. With this form of barrier distortion, the constitutive equation prediction the steady creep behavior of aluminum, tin and lead over a wide range of temperature and stress.
An internal variable constitutive model for the large deformation of metals at high temperatures
NASA Technical Reports Server (NTRS)
Brown, Stuart; Anand, Lallit
1988-01-01
The advent of large deformation finite element methodologies is beginning to permit the numerical simulation of hot working processes whose design until recently has been based on prior industrial experience. Proper application of such finite element techniques requires realistic constitutive equations which more accurately model material behavior during hot working. A simple constitutive model for hot working is the single scalar internal variable model for isotropic thermal elastoplasticity proposed by Anand. The model is recalled and the specific scalar functions, for the equivalent plastic strain rate and the evolution equation for the internal variable, presented are slight modifications of those proposed by Anand. The modified functions are better able to represent high temperature material behavior. The monotonic constant true strain rate and strain rate jump compression experiments on a 2 percent silicon iron is briefly described. The model is implemented in the general purpose finite element program ABAQUS.
NASA Technical Reports Server (NTRS)
Saleeb, A. F.; Chang, T. Y. P.; Wilt, T.; Iskovitz, I.
1989-01-01
The research work performed during the past year on finite element implementation and computational techniques pertaining to high temperature composites is outlined. In the present research, two main issues are addressed: efficient geometric modeling of composite structures and expedient numerical integration techniques dealing with constitutive rate equations. In the first issue, mixed finite elements for modeling laminated plates and shells were examined in terms of numerical accuracy, locking property and computational efficiency. Element applications include (currently available) linearly elastic analysis and future extension to material nonlinearity for damage predictions and large deformations. On the material level, various integration methods to integrate nonlinear constitutive rate equations for finite element implementation were studied. These include explicit, implicit and automatic subincrementing schemes. In all cases, examples are included to illustrate the numerical characteristics of various methods that were considered.
Equation of state for polytetrafluoroethylene (PTFE) and mixtures with PTFE
NASA Astrophysics Data System (ADS)
Wu, Zhibo
In this work, the goals are to explore the potential of different structural energetic materials that are made from different combinations of reactive materials, different binders and voids. In such exploratory studies, it is necessary to consider different ratios of the basic ingredients. Because the dual functional energetic structural materials are used in applications where the resulting structure encounters high intensity impact loads, impact and penetration into selected targets and shock induced chemical reactions, it is also necessary to consider large or finite deformations of these materials. The experimental techniques that are used consist of techniques such as the gas gun tests and flyer plate impact tests. To accomplish the exploratory tasks that are stated in the last few sentences requires a very large number of tests. Thus it is both expensive and time intensive. Thus, it is necessary to consider alternate methods of determining the constitutive equations without conducting tests. This is accomplished by the use of ab initio methods to obtain the constitutive relations and foundations for chemical reactions in structural energetic materials without conducting tests. This needs an exploration of the analysis beyond continuum. First, it is necessary to study the quantum many body problem to quantitatively determine the internal energy of the material when subjected to different strain conditions. The current state of the technology is such that it is not possible to obtain an exact solution to the needed quantum many body problem that is modeled by the Schrodinger's equations. It is possible to solve these equations approximately by the approximation of density functional theory and Kohn Sham approximate equations. This however, yields only energies at the ground state or at absolute 0°K. Thus it becomes necessary to add both the lattice thermal contributions due to phonons and electron thermal contribution. Then, resulting energy is used to bridge
Constitutive modeling for isotropic materials (HOST)
NASA Technical Reports Server (NTRS)
Chan, Kwai S.; Lindholm, Ulric S.; Bodner, S. R.; Hill, Jeff T.; Weber, R. M.; Meyer, T. G.
1986-01-01
The results of the third year of work on a program which is part of the NASA Hot Section Technology program (HOST) are presented. The goals of this program are: (1) the development of unified constitutive models for rate dependent isotropic materials; and (2) the demonstration of the use of unified models in structural analyses of hot section components of gas turbine engines. The unified models selected for development and evaluation are those of Bodner-Partom and of Walker. A test procedure was developed for assisting the generation of a data base for the Bodner-Partom model using a relatively small number of specimens. This test procedure involved performing a tensile test at a temperature of interest that involves a succession of strain-rate changes. The results for B1900+Hf indicate that material constants related to hardening and thermal recovery can be obtained on the basis of such a procedure. Strain aging, thermal recovery, and unexpected material variations, however, preluded an accurate determination of the strain-rate sensitivity parameter is this exercise. The effects of casting grain size on the constitutive behavior of B1900+Hf were studied and no particular grain size effect was observed. A systematic procedure was also developed for determining the material constants in the Bodner-Partom model. Both the new test procedure and the method for determining material constants were applied to the alternate material, Mar-M247 . Test data including tensile, creep, cyclic and nonproportional biaxial (tension/torsion) loading were collected. Good correlations were obtained between the Bodner-Partom model and experiments. A literature survey was conducted to assess the effects of thermal history on the constitutive behavior of metals. Thermal history effects are expected to be present at temperature regimes where strain aging and change of microstructure are important. Possible modifications to the Bodner-Partom model to account for these effects are outlined
Numerically abnormal chromosome constitutions in humans
1993-12-31
Chapter 24, discusses numerically abnormal chromosome constitutions in humans. This involves abnormalities of human chromosome number, including polyploidy (when the number of sets of chromosomes increases) and aneuploidy (when the number of individual normal chromosomes changes). Chapter sections discuss the following chromosomal abnormalities: human triploids, imprinting and uniparental disomy, human tetraploids, hydatidiform moles, anomalies caused by chromosomal imbalance, 13 trisomy (D{sub 1} trisomy, Patau syndrome), 21 trisomy (Down syndrome), 18 trisomy syndrome (Edwards syndrome), other autosomal aneuploidy syndromes, and spontaneous abortions. The chapter concludes with remarks on the nonrandom participation of chromosomes in trisomy. 69 refs., 3 figs., 4 tabs.
Evaluation of constitutive models for crushed salt
Callahan, G.D.; Loken, M.C. [RE Hurtado, L.D.; Hansen, F.D.
1996-05-01
Three constitutive models are recommended as candidates for describing the deformation of crushed salt. These models are generalized to three-dimensional states of stress to include the effects of mean and deviatoric stress and modified to include effects of temperature, grain size, and moisture content. A database including hydrostatic consolidation and shear consolidation tests conducted on Waste Isolation Pilot Plant (WIPP) and southeastern New Mexico salt is used to determine material parameters for the models. To evaluate the capability of the models, parameter values obtained from fitting the complete database are used to predict the individual tests. Finite element calculations of a WIPP shaft with emplaced crushed salt demonstrate the model predictions.
Photoreceptor cells constitutively express functional TLR4
Tu, Zhidan; Portillo, Jose-Andres; Howell, Scott; Bu, Hong; Subauste, Carlos S.; Al-Ubaidi, Muayyad R; Pearlman, Eric; Lin, Feng
2010-01-01
Toll-like receptor 4 (TLR4) is expressed on a number of cells including neurons in the brain. However, it has yet to be determined if TLR4 is expressed on photoreceptor cells in the retina. In this report, we examined primary photoreceptor cells and an established photoreceptor cell line (661W). We found that functional TLR4 is constitutively expressed on photoreceptor cells, and can be activated by LPS. We conclude that TLR4 on photoreceptor cells could directly contribute to retinal inflammatory diseases and photoreceptor cell survival. PMID:20801528
Constitutive parameter measurements of lossy materials
NASA Technical Reports Server (NTRS)
Dominek, A.; Park, A.
1989-01-01
The electrical constitutive parameters of lossy materials are considered. A discussion of the NRL arch for lossy coatings is presented involving analytical analyses of the reflected field using the geometrical theory of diffraction (GTD) and physical optics (PO). The actual values for these parameters can be obtained through a traditional transmission technique which is examined from an error analysis standpoint. Alternate sample geometries are suggested for this technique to reduce sample tolerance requirements for accurate parameter determination. The performance for one alternate geometry is given.
Civil and Constitutional Rights of Adjudicated Youth.
Landess, Jacqueline
2016-01-01
Mental health clinicians serving child and adolescent patients are frequently asked to evaluate youth who have been arrested for various offenses or who are otherwise involved with the juvenile justice system. To help orient clinicians and other stakeholders involved with such cases, this article describes the evolution of the juvenile justice system and summarizes the history and current status of the civil and constitutional rights of youth involved in the adjudicatory process. This article also points out key areas in which due process rights are still evolving, particularly in the case of status offenders.
Generalized in situ adaptive tabulation for constitutive model evaluation in plasticity
Arsenlis, A; Barton, N; Becker, R; Rudd, R
2005-04-28
A database storage, search and retrieval method of constitutive model responses for use in plasticity simulations is developed to increase the computational efficiency of finite element simulations employing complex non-linear material models. The method is based in the in situ adaptive tabulation method that has been successfully applied in the field of combustion chemistry, but is significantly modified to better handle the system of equations in plasticity. When using the database, the material response is estimated by a linear extrapolation from an appropriate database entry. This is shown to provide a response with an acceptable error tolerance. Two different example problems are chosen to demonstrate the behavior of the constitutive model estimation technique: a dynamic shock simulation, and a quasi-static inhomogeneous deformation simulation. This generalized in situ adaptive tabulation method shows promise for enabling simulations with complex multi-physics and multi-length scale constitutive descriptions.
The effect of the constitutive response on the predicted temperatures in copper jets
Nikkel, D.J. Jr.; Lassila, D.H.
1993-08-01
This paper examines the effect of various elements in a set constitutive equations on predicted stress and temperature response of material undergoing pressure and strain histories representative of those in copper jets formed by shaped charges. It is found that the dependence of the flow stress on hydrostatic pressure, which enters here through the pressure dependence of the shear modulus, has a significant effect on predicted flow stress and hence temperature.
Key, S.W.; Krieg, R.D.
1980-01-01
A number of complex issues are addressed which will allow the incorporation of finite strain, inelastic material behavior into the piecewise numerical construction of solutions in solid mechanics. Without recourse to extensive continuum mechanics preliminaries, an elementary time independent plasticity model, an elementary time dependent creep model, and a viscoelastic model are introduced as examples of constitutive equations which are routinely used in engineering calculations. The constitutive equations are all suitable for problems involving large deformations and finite strains. The plasticity and creep models are in rate form and use the symmetric part of the velocity gradient or the stretching to compute the co-rotational time derivative of the Cauchy stress. The viscoelastic model computes the current value of the Cauchy stress from a hereditary integral of a materially invariant form of the stretching history. The current configuration is selected for evaluation of equilibrium as opposed to either the reference configuration or the last established equilibrium configuration. The process of strain incrementation is examined in some depth and the stretching evaluated at the midinterval multiplied by the time step is identified as the appropriate finite strain increment to use with the selected form of the constitutive equations. Discussed is the conversion of rotation rates based on the spin into incremental orthogonal rotations which are then used to update stresses and state variables due to rigid body rotation during the load increment. Comments and references to the literature are directed at numerical integration of the constitutive equations with an emphasis on doing this accurately, if not exactly, for any time step and stretching. This material taken collectively provides an approach to numerical implementation which is marked by its simplicity.
Constitutive modelling of magnetic shape memory alloys with discrete and continuous symmetries
Haldar, K.; Lagoudas, D. C.
2014-01-01
A free energy-based constitutive formulation is considered for magnetic shape memory alloys. Internal state variables are introduced whose evolution describes the transition from reference state to the deformed and transformed one. We impose material symmetry restrictions on the Gibbs free energy and on the evolution equations of the internal state variables. Discrete symmetry is considered for single crystals, whereas continuous symmetry is considered for polycrystalline materials. PMID:25197247
Application of symbolic computations to the constitutive modeling of structural materials
NASA Technical Reports Server (NTRS)
Arnold, Steven M.; Tan, H. Q.; Dong, X.
1990-01-01
In applications involving elevated temperatures, the derivation of mathematical expressions (constitutive equations) describing the material behavior can be quite time consuming, involved and error-prone. Therefore intelligent application of symbolic systems to faciliate this tedious process can be of significant benefit. Presented here is a problem oriented, self contained symbolic expert system, named SDICE, which is capable of efficiently deriving potential based constitutive models in analytical form. This package, running under DOE MACSYMA, has the following features: (1) potential differentiation (chain rule), (2) tensor computations (utilizing index notation) including both algebraic and calculus; (3) efficient solution of sparse systems of equations; (4) automatic expression substitution and simplification; (5) back substitution of invariant and tensorial relations; (6) the ability to form the Jacobian and Hessian matrix; and (7) a relational data base. Limited aspects of invariant theory were also incorporated into SDICE due to the utilization of potentials as a starting point and the desire for these potentials to be frame invariant (objective). The uniqueness of SDICE resides in its ability to manipulate expressions in a general yet pre-defined order and simplify expressions so as to limit expression growth. Results are displayed, when applicable, utilizing index notation. SDICE was designed to aid and complement the human constitutive model developer. A number of examples are utilized to illustrate the various features contained within SDICE. It is expected that this symbolic package can and will provide a significant incentive to the development of new constitutive theories.
NASA Technical Reports Server (NTRS)
Dame, L. T.; Stouffer, D. C.
1986-01-01
A tool for the mechanical analysis of nickel base single crystal superalloys, specifically Rene N4, used in gas turbine engine components is developed. This is achieved by a rate dependent anisotropic constitutive model implemented in a nonlinear three dimensional finite element code. The constitutive model is developed from metallurigical concepts utilizing a crystallographic approach. A non Schmid's law formulation is used to model the tension/compression asymmetry and orientation dependence in octahedral slip. Schmid's law is a good approximation to the inelastic response of the material in cube slip. The constitutive equations model the tensile behavior, creep response, and strain rate sensitivity of these alloys. Methods for deriving the material constants from standard tests are presented. The finite element implementation utilizes an initial strain method and twenty noded isoparametric solid elements. The ability to model piecewise linear load histories is included in the finite element code. The constitutive equations are accurately and economically integrated using a second order Adams-Moulton predictor-corrector method with a dynamic time incrementing procedure. Computed results from the finite element code are compared with experimental data for tensile, creep and cyclic tests at 760 deg C. The strain rate sensitivity and stress relaxation capabilities of the model are evaluated.
Relationships among certain joint constitutive models.
Segalman, Daniel Joseph; Starr, Michael James
2004-09-01
In a recent paper, Starr and Segalman demonstrated that any Masing model can be represented as a parallel-series Iwan model. A preponderance of the constitutive models that have been suggested for simulating mechanical joints are Masing models, and the purpose of this discussion is to demonstrate how the Iwan representation of those models can yield insight into their character. In particular, this approach can facilitate a critical comparison among numerous plausible constitutive models. It is explicitly shown that three-parameter models such as Smallwood's (Ramberg-Osgood) calculate parameters in such a manner that macro-slip is not an independent parameter, yet the model admits macro-slip. The introduction of a fourth parameter is therefore required. It is shown that when a macro-slip force is specified for the Smallwood model the result is a special case of the Segalman four-parameter model. Both of these models admit a slope discontinuity at the inception of macro-slip. A five-parameter model that has the beneficial features of Segalman's four-parameter model is proposed. This model manifests a force-displacement curve having a continuous first derivative.
Space shuttle propellant constitutive law verification tests
NASA Technical Reports Server (NTRS)
Thompson, James R.
1995-01-01
As part of the Propellants Task (Task 2.0) on the Solid Propulsion Integrity Program (SPIP), a database of material properties was generated for the Space Shuttle Redesigned Solid Rocket Motor (RSRM) PBAN-based propellant. A parallel effort on the Propellants Task was the generation of an improved constitutive theory for the PBAN propellant suitable for use in a finite element analysis (FEA) of the RSRM. The outcome of an analysis with the improved constitutive theory would be more reliable prediction of structural margins of safety. The work described in this report was performed by Materials Laboratory personnel at Thiokol Corporation/Huntsville Division under NASA contract NAS8-39619, Mod. 3. The report documents the test procedures for the refinement and verification tests for the improved Space Shuttle RSRM propellant material model, and summarizes the resulting test data. TP-H1148 propellant obtained from mix E660411 (manufactured February 1989) which had experienced ambient igloo storage in Huntsville, Alabama since January 1990, was used for these tests.
Constitutive modeling for isotropic materials (HOST)
NASA Technical Reports Server (NTRS)
Lindholm, U. S.; Chan, K. S.; Bodner, S. R.; Weber, R. M.; Walker, K. P.; Cassenti, B. N.
1985-01-01
This report presents the results of the second year of work on a problem which is part of the NASA HOST Program. Its goals are: (1) to develop and validate unified constitutive models for isotropic materials, and (2) to demonstrate their usefulness for structural analyses of hot section components of gas turbine engines. The unified models selected for development and evaluation are that of Bodner-Partom and Walker. For model evaluation purposes, a large constitutive data base is generated for a B1900 + Hf alloy by performing uniaxial tensile, creep, cyclic, stress relation, and thermomechanical fatigue (TMF) tests as well as biaxial (tension/torsion) tests under proportional and nonproportional loading over a wide range of strain rates and temperatures. Systematic approaches for evaluating material constants from a small subset of the data base are developed. Correlations of the uniaxial and biaxial tests data with the theories of Bodner-Partom and Walker are performed to establish the accuracy, range of applicability, and integability of the models. Both models are implemented in the MARC finite element computer code and used for TMF analyses. Benchmark notch round experiments are conducted and the results compared with finite-element analyses using the MARC code and the Walker model.
[Body composition and constitution: a constitutional syndrome (1st of 2 parts)].
Terán Díaz, E
1999-04-01
Constitutional syndrome alters body constitution modifying (usually decreasing) two of its dimensions--weight and perimeters--by changing the composition of one, several or every body levels. Apart of the cause, the basic physiopathological process that characterizes this new syndrome is the amino acid mobilization from the muscle (proteolysis). As soon as fat loss has no consequence to the organism, proteolysis reduces the muscle mass and life is in danger. Actually, there is no effective treatment to improve the nitrogen balance by medication or hormones in speed catabolic states but it can also approach us to more proper therapeutics for these so frequent processes in clinic.
Rotational and constitutional dynamics of caged supramolecules
Kühne, Dirk; Klappenberger, Florian; Krenner, Wolfgang; Klyatskaya, Svetlana; Ruben, Mario; Barth, Johannes V.
2010-01-01
The confinement of molecular species in nanoscale environments leads to intriguing dynamic phenomena. Notably, the organization and rotational motions of individual molecules were controlled by carefully designed, fully supramolecular host architectures. Here we use an open 2D coordination network on a smooth metal surface to steer the self-assembly of discrete trimeric guest units, identified as noncovalently bound dynamers. Each caged chiral supramolecule performs concerted, chirality-preserving rotary motions within the template honeycomb pore, which are visualized and quantitatively analyzed using temperature-controlled scanning tunneling microscopy. Furthermore, with higher thermal energies, a constitutional system dynamics appears, which is revealed by monitoring repetitive switching events of the confined supramolecules’ chirality signature, reflecting decay and reassembly of the caged units. PMID:21098303
[Constitutions and generalities in traditional Tibetan medicine].
Rovere, P M
1986-04-28
The present work is the result of a preliminary study promoted by C.I.S.ME.T. (the International Tibetan Medicine Study Centre) and aims to unify the diagnostic and therapeutic language of various medical cultures. In line with the spirit of the W.H.O. aimed at safeguarding the cultural heritage represented by popular and traditional medicine, encouraged by the Tibetan Medical Centre and under the auspices of His Holiness the Dalai Lama a terminological and conceptual integration of the basic elements of traditional Tibetan medicine is proposed. The Rlung, Bad Kan, Mkris Pa constitution is correlated with embryological anatomy. The 5 exhalations, 5 biles and 5 phlegbs are analysed from a tissue viewpoint with a search for parallels with embryological tissues.
Constituting objectivity: Transcendental perspectives on modern physics
NASA Astrophysics Data System (ADS)
Everett, Jonathan
2012-05-01
There is increasing interest in exploring Kantian approaches in the study of the history and philosophy of physics. The most well-known examples of this trend-Friedman's (2001), Ryckman's (2005) and DiSalle's (2006)-focus on Kantianism in the context of the development of the general theory of relativity. The edited collection Constituting Objectivity seeks to develop key Kantian insights-in the most part-in the context of later developments in physics: as well as discussing relativity the volume also provides Kantian interpretations of Bohr's development of quantum theory and continues to provide Kantian insight from later interpretations of quantum mechanics all the way through to considering noncommutative geometry and loop quantum gravity. The volume contains papers on a wide variety of subjects and offers an essential introduction to the breadth of Kantian trends in modern physics.
Laboratory constitutive characterization of cellular concrete.
Hardy, Robert Douglas; Lee, Moo Yul; Bronowski, David R.
2004-03-01
To establish mechanical material properties of cellular concrete mixes, a series of quasi-static, compression and tension tests have been completed. This report summarizes the test methods, set-up, relevant observations, and results from the constitutive experimental efforts. Results from the uniaxial and triaxial compression tests established failure criteria for the cellular concrete in terms of stress invariants I{sub 1} and J{sub 2}. {radical}J{sub 2} (MPa) = 297.2 - 278.7 exp{sup -0.000455 I}{sub 1}{sup (MPa)} for the 90-pcf concrete {radical}J{sub 2} (MPa) = 211.4 - 204.2 exp {sup -0.000628 I}{sub 1}{sup (MPa)} for the 60-pcf concrete
Constitutive Models for Shape Memory Alloy Polycrystals
NASA Technical Reports Server (NTRS)
Comstock, R. J., Jr.; Somerday, M.; Wert, J. A.
1996-01-01
Shape memory alloys (SMA) exhibiting the superelastic or one-way effects can produce large recoverable strains upon application of a stress. In single crystals this stress and resulting strain are very orientation dependent. We show experimental stress/strain curves for a Ni-Al single crystal for various loading orientations. Also shown are model predictions; the open and closed circles indicate recoverable strains obtained at various stages in the transformation process. Because of the strong orientation dependence of shape memory properties, crystallographic texture can be expected to play an important role in the mechanical behavior of polycrystalline SMA. It is desirable to formulate a constitutive model to better understand and exploit the unique properties of SMA.
Multiscale constitutive modeling of polymer materials
NASA Astrophysics Data System (ADS)
Valavala, Pavan Kumar
Materials are inherently multi-scale in nature consisting of distinct characteristics at various length scales from atoms to bulk material. There are no widely accepted predictive multi-scale modeling techniques that span from atomic level to bulk relating the effects of the structure at the nanometer (10-9 meter) on macro-scale properties. Traditional engineering deals with treating matter as continuous with no internal structure. In contrast to engineers, physicists have dealt with matter in its discrete structure at small length scales to understand fundamental behavior of materials. Multiscale modeling is of great scientific and technical importance as it can aid in designing novel materials that will enable us to tailor properties specific to an application like multi-functional materials. Polymer nanocomposite materials have the potential to provide significant increases in mechanical properties relative to current polymers used for structural applications. The nanoscale reinforcements have the potential to increase the effective interface between the reinforcement and the matrix by orders of magnitude for a given reinforcement volume fraction as relative to traditional micro- or macro-scale reinforcements. To facilitate the development of polymer nanocomposite materials, constitutive relationships must be established that predict the bulk mechanical properties of the materials as a function of the molecular structure. A computational hierarchical multiscale modeling technique is developed to study the bulk-level constitutive behavior of polymeric materials as a function of its molecular chemistry. Various parameters and modeling techniques from computational chemistry to continuum mechanics are utilized for the current modeling method. The cause and effect relationship of the parameters are studied to establish an efficient modeling framework. The proposed methodology is applied to three different polymers and validated using experimental data available in
NASA Astrophysics Data System (ADS)
Gu, Sendong; Zhang, Liwen; Zhang, Chi; Shen, Wenfei
2016-03-01
The hot deformation characteristics of nickel-based alloy Nimonic 80A were investigated by isothermal compression tests conducted in the temperature range of 1,000-1,200°C and the strain rate range of 0.01—5 s-1 on a Gleeble-1500 thermomechanical simulator. In order to establish the constitutive models for dynamic recrystallization (DRX) behavior and flow stress of Nimonic 80A, the material constants α, n and DRX activation energy Q in the constitutive models were calculated by the regression analysis of the experimental data. The dependences of initial stress, saturation stress, steady-state stress, dynamic recovery (DRV) parameter, peak strain, critical strain and DRX grain size on deformation parameters were obtained. Then, the Avrami equation including the critical strain for DRX and the peak strain as a function of strain was established to describe the DRX volume fraction. Finally, the constitutive model for flow stress of Nimonic 80A was developed in DRV region and DRX region, respectively. The flow stress values predicted by the constitutive model are in good agreement with the experimental ones, which indicates that the constitutive model can give an accurate estimate for the flow stress of Nimonic 80A under the deformation conditions.
ERIC Educational Resources Information Center
Thomas, Ann Van Wynen; Thomas, A. J., Jr.
This report discusses the constitutionality of state aid to church-related institutions of higher education. The introduction deals with the important role that private institutions play in the total system of higher education, the seriousness of their financial plight, and the necessity for increased state aid to these institutions. Sections 2…
ERIC Educational Resources Information Center
Emenaker, Ryan
2014-01-01
"Pin-the-Tail-on-the-Constitution" is an engaged-learning activity that has been conducted in 26 classes over the past four years. The activity teaches multiple themes commonly included in a variety of courses on American politics such as federalism, congressional powers, the role of the federal courts, and the relevance of the commerce…
NASA Astrophysics Data System (ADS)
Kostov, Ivan; Serban, Didina; Volin, Dmytro
2008-08-01
We give a realization of the Beisert, Eden and Staudacher equation for the planar Script N = 4 supersymetric gauge theory which seems to be particularly useful to study the strong coupling limit. We are using a linearized version of the BES equation as two coupled equations involving an auxiliary density function. We write these equations in terms of the resolvents and we transform them into a system of functional, instead of integral, equations. We solve the functional equations perturbatively in the strong coupling limit and reproduce the recursive solution obtained by Basso, Korchemsky and Kotański. The coefficients of the strong coupling expansion are fixed by the analyticity properties obeyed by the resolvents.
Einstein equation at singularities
NASA Astrophysics Data System (ADS)
Stoica, Ovidiu-Cristinel
2014-02-01
Einstein's equation is rewritten in an equivalent form, which remains valid at the singularities in some major cases. These cases include the Schwarzschild singularity, the Friedmann-Lemaître-Robertson-Walker Big Bang singularity, isotropic singularities, and a class of warped product singularities. This equation is constructed in terms of the Ricci part of the Riemann curvature (as the Kulkarni-Nomizu product between Einstein's equation and the metric tensor).
Solving Ordinary Differential Equations
NASA Technical Reports Server (NTRS)
Krogh, F. T.
1987-01-01
Initial-value ordinary differential equation solution via variable order Adams method (SIVA/DIVA) package is collection of subroutines for solution of nonstiff ordinary differential equations. There are versions for single-precision and double-precision arithmetic. Requires fewer evaluations of derivatives than other variable-order Adams predictor/ corrector methods. Option for direct integration of second-order equations makes integration of trajectory problems significantly more efficient. Written in FORTRAN 77.
Generalized Langevin theory for inhomogeneous fluids: The equations of motion
NASA Astrophysics Data System (ADS)
Grant, Martin; Desai, Rashmi C.
1982-05-01
We use the generalized Langevin approach to study the dynamical correlations in an inhomogeneous system. The equations of motion (formally exact) are obtained for the number density, momentum density, energy density, stress tensor, and heat flux. We evaluate all the relevant sum rules appearing in the frequency matrix exactly in terms of microscopic pair potentials and an external field. We show using functional derivatives how these microscopic sum rules relate to more familiar, though now nonlocal, hydrodynamiclike quantities. The set of equations is closed by a Markov approximation in the equations for stress tensor and heat flux. As a result, these equations become analogous to Grad's 13-moment equations for low-density fluids and constitute a generalization to inhomogeneous fluids of the work of Schofield and Akcasu-Daniels. We also indicate how the resulting general set of equations would simplify for systems in which the inhomogeneity is unidirectional, e.g., a liquid-vapor interface.
Implementing the Equal Access Act and State Constitutional Provisions.
ERIC Educational Resources Information Center
Bjorklun, Eugene C.
1992-01-01
Examines the issue of whether implementation of the Equal Access Act would violate the constitutions of some states that require a stricter separation of church and state than the federal Constitution. (MLF)
Close view of the south facade on Constitution Avenue to ...
Close view of the south facade on Constitution Avenue to show main entrance - United States Department of Justice, Constitution Avenue between Ninth & Tenth Streets, Northwest, Washington, District of Columbia, DC
Perspective view looking along the Constitution Avenue facade, showing the ...
Perspective view looking along the Constitution Avenue facade, showing the twenty-seven bays and the three central arches that mark the entrance to the building - Internal Revenue Service Headquarters Building, 1111 Constitution Avenue Northwest, Washington, District of Columbia, DC
Close view of the Constitution Avenue elevation to show arched ...
Close view of the Constitution Avenue elevation to show arched gateways and pedimented pavilion ("Commerce and Communication" sculpted pediment) - Interstate Commerce Commission, Constitution Avenue between Twelfth and Fourteenth streets, Washington, District of Columbia, DC
Solving the dynamic rupture problem with different numerical approaches and constitutive laws
Bizzarri, A.; Cocco, M.; Andrews, D.J.; Boschi, Enzo
2001-01-01
We study the dynamic initiation, propagation and arrest of a 2-D in-plane shear rupture by solving the elastodynamic equation by using both a boundary integral equation method and a finite difference approach. For both methods we adopt different constitutive laws: a slip-weakening (SW) law, with constant weakening rate, and rate- and state-dependent friction laws (Dieterich-Ruina). Our numerical procedures allow the use of heterogeneous distributions of constitutive parameters along the fault for both formulations. We first compare the two solution methods with an SW law, emphasizing the required stability conditions to achieve a good resolution of the cohesive zone and to avoid artificial complexity in the solutions. Our modelling results show that the two methods provide very similar time histories of dynamic source parameters. We point out that, if a careful control of resolution and stability is performed, the two methods yield identical solutions. We have also compared the rupture evolution resulting from an SW and a rate- and state-dependent friction law. This comparison shows that despite the different constitutive formulations, a similar behaviour is simulated during the rupture propagation and arrest. We also observe a crack tip bifurcation and a jump in rupture velocity (approaching the P-wave speed) with the Dieterich-Ruina (DR) law. The rupture arrest at a barrier (high strength zone) and the barrier-healing mechanism are also reproduced by this law. However, this constitutive formulation allows the simulation of a more general and complex variety of rupture behaviours. By assuming different heterogeneous distributions of the initial constitutive parameters, we are able to model a barrier-healing as well as a self-healing process. This result suggests that if the heterogeneity of the constitutive parameters is taken into account, the different healing mechanisms can be simulated. We also study the nucleation phase duration Tn, defined as the time
Constitutive Theory Developed for Monolithic Ceramic Materials
NASA Technical Reports Server (NTRS)
Janosik, Lesley A.
1998-01-01
With the increasing use of advanced ceramic materials in high-temperature structural applications such as advanced heat engine components, the need arises to accurately predict thermomechanical behavior that is inherently time-dependent and that is hereditary in the sense that the current behavior depends not only on current conditions but also on the material's thermomechanical history. Most current analytical life prediction methods for both subcritical crack growth and creep models use elastic stress fields to predict the time-dependent reliability response of components subjected to elevated service temperatures. Inelastic response at high temperatures has been well documented in the materials science literature for these material systems, but this issue has been ignored by the engineering design community. From a design engineer's perspective, it is imperative to emphasize that accurate predictions of time-dependent reliability demand accurate stress field information. Ceramic materials exhibit different time-dependent behavior in tension and compression. Thus, inelastic deformation models for ceramics must be constructed in a fashion that admits both sensitivity to hydrostatic stress and differing behavior in tension and compression. A number of constitutive theories for materials that exhibit sensitivity to the hydrostatic component of stress have been proposed that characterize deformation using time-independent classical plasticity as a foundation. However, none of these theories allow different behavior in tension and compression. In addition, these theories are somewhat lacking in that they are unable to capture the creep, relaxation, and rate-sensitive phenomena exhibited by ceramic materials at high temperatures. The objective of this effort at the NASA Lewis Research Center has been to formulate a macroscopic continuum theory that captures these time-dependent phenomena. Specifically, the effort has focused on inelastic deformation behavior associated
Frederick Douglass Changed My Mind about the Constitution
ERIC Educational Resources Information Center
Oakes, James
2008-01-01
Frederick Douglass dramatically and publicly changed his own mind about the Constitution. Like Frederick Douglass, the author had originally viewed the Constitution as pro-slavery. Yet a close look at Douglass's writings revealed a Constitution that empowered the federal government to abolish slavery.
Resolution and Letter to Congress from the Constitutional Convention
ERIC Educational Resources Information Center
Potter, Lee Ann
2005-01-01
This article explores the drafting of the United States Constitution. The United States Constitution is the longest-lasting written national constitution in the world. Its four parchment pages serve as the blueprint for a government under which more than 290 million Americans live. It holds great significance for the American people and for others…
The Separation of Church and State. Exploring the Constitution Series.
ERIC Educational Resources Information Center
McWhirter, Darien A.
This textbook on the separation of church and state continues the "Exploring the Constitution Series," which introduces important areas of constitutional law. Intended to serve either as a reference work, a supplement to a standard textbook, or as the textbook for a course, this volume covers the constitutional issues of prayer in public schools,…
42 CFR 23.28 - What events constitute default?
Code of Federal Regulations, 2010 CFR
2010-10-01
... 42 Public Health 1 2010-10-01 2010-10-01 false What events constitute default? 23.28 Section 23.28... SERVICE CORPS Private Practice Special Loans for Former Corps Members § 23.28 What events constitute default? The following events will constitute defaults of the loan agreement: (a) Failure to make...
42 CFR 23.28 - What events constitute default?
Code of Federal Regulations, 2011 CFR
2011-10-01
... 42 Public Health 1 2011-10-01 2011-10-01 false What events constitute default? 23.28 Section 23.28... SERVICE CORPS Private Practice Special Loans for Former Corps Members § 23.28 What events constitute default? The following events will constitute defaults of the loan agreement: (a) Failure to make...
42 CFR 23.28 - What events constitute default?
Code of Federal Regulations, 2014 CFR
2014-10-01
... 42 Public Health 1 2014-10-01 2014-10-01 false What events constitute default? 23.28 Section 23.28... SERVICE CORPS Private Practice Special Loans for Former Corps Members § 23.28 What events constitute default? The following events will constitute defaults of the loan agreement: (a) Failure to make...
42 CFR 23.28 - What events constitute default?
Code of Federal Regulations, 2013 CFR
2013-10-01
... 42 Public Health 1 2013-10-01 2013-10-01 false What events constitute default? 23.28 Section 23.28... SERVICE CORPS Private Practice Special Loans for Former Corps Members § 23.28 What events constitute default? The following events will constitute defaults of the loan agreement: (a) Failure to make...
42 CFR 23.28 - What events constitute default?
Code of Federal Regulations, 2012 CFR
2012-10-01
... 42 Public Health 1 2012-10-01 2012-10-01 false What events constitute default? 23.28 Section 23.28... SERVICE CORPS Private Practice Special Loans for Former Corps Members § 23.28 What events constitute default? The following events will constitute defaults of the loan agreement: (a) Failure to make...
Constitution Day: Start the School Year with Civics
ERIC Educational Resources Information Center
Lesser, Eli J.
2006-01-01
The celebration and recognition of Constitution Day on September 17th is now required by federal law. The new law, known colloquially as the Byrd Amendment, requires all schools receiving any federal assistance, from kindergarten to higher education, to teach students about the Constitution on Constitution Day. The concept of a school's civic…
29 CFR 452.3 - Interpretations of constitution and bylaws.
Code of Federal Regulations, 2013 CFR
2013-07-01
... 29 Labor 2 2013-07-01 2013-07-01 false Interpretations of constitution and bylaws. 452.3 Section... REPORTING AND DISCLOSURE ACT OF 1959 General Considerations § 452.3 Interpretations of constitution and bylaws. The interpretation consistently placed on a union's constitution by the responsible...
29 CFR 452.3 - Interpretations of constitution and bylaws.
Code of Federal Regulations, 2014 CFR
2014-07-01
... 29 Labor 2 2014-07-01 2014-07-01 false Interpretations of constitution and bylaws. 452.3 Section... REPORTING AND DISCLOSURE ACT OF 1959 General Considerations § 452.3 Interpretations of constitution and bylaws. The interpretation consistently placed on a union's constitution by the responsible...
29 CFR 452.3 - Interpretations of constitution and bylaws.
Code of Federal Regulations, 2012 CFR
2012-07-01
... 29 Labor 2 2012-07-01 2012-07-01 false Interpretations of constitution and bylaws. 452.3 Section... REPORTING AND DISCLOSURE ACT OF 1959 General Considerations § 452.3 Interpretations of constitution and bylaws. The interpretation consistently placed on a union's constitution by the responsible...
29 CFR 452.3 - Interpretations of constitution and bylaws.
Code of Federal Regulations, 2011 CFR
2011-07-01
... 29 Labor 2 2011-07-01 2011-07-01 false Interpretations of constitution and bylaws. 452.3 Section... REPORTING AND DISCLOSURE ACT OF 1959 General Considerations § 452.3 Interpretations of constitution and bylaws. The interpretation consistently placed on a union's constitution by the responsible...
29 CFR 452.3 - Interpretations of constitution and bylaws.
Code of Federal Regulations, 2010 CFR
2010-07-01
... 29 Labor 2 2010-07-01 2010-07-01 false Interpretations of constitution and bylaws. 452.3 Section... REPORTING AND DISCLOSURE ACT OF 1959 General Considerations § 452.3 Interpretations of constitution and bylaws. The interpretation consistently placed on a union's constitution by the responsible...
Health care for Micronesians and constitutional rights.
Shek, Dina; Yamada, Seiji
2011-11-01
Under the Compacts of Free Association (COFA), people from the Freely Associated States--the Republic of Palau (ROP), the Republic of the Marshall Islands (RMI), and the Federated States of Micronesia (FSM)--have been migrating to the United States in increasing numbers. In 1996, Congress passed broad welfare reform (Personal Responsibility and Work Opportunity Reconciliation Act) which limited certain federal benefits previously available to COFA migrants, including Medicaid benefits. Prior to July 2010, the State of Hawai'i had continued to include COFA migrants under its state-funded Medicaid program. In the face of budget constraints, the State removed these people from its Medicaid rolls. A challenge on the legal basis of the denial of equal protection of the laws, ie, the Fourteenth Amendment to the US Constitution, was successful in reinstating health care to the COFA migrants in December 2010. From the health worker's perspective, regardless of various social justice arguments that may have been marshaled in favor of delivering health care to the people, it was an appeal to the judicial system that succeeded. From the attorney's perspective, the legal victories are potentially limited to the four walls of the courtroom without community involvement and related social justice movements. Together, the authors propose that in order to better address the issue of health care access for Micronesian peoples, we must work together, as health and legal advocates, to define a more robust vision of both systems that includes reconciliation and community engagement. PMID:22235150
Improvements to constitutive material model for fabrics
NASA Astrophysics Data System (ADS)
Morea, Mihai I.
2011-12-01
The high strength to weight ratio of woven fabric offers a cost effective solution to be used in a containment system for aircraft propulsion engines. Currently, Kevlar is the only Federal Aviation Administration (FAA) approved fabric for usage in systems intended to mitigate fan blade-out events. This research builds on an earlier constitutive model of Kevlar 49 fabric developed at Arizona State University (ASU) with the addition of new and improved modeling details. Latest stress strain experiments provided new and valuable data used to modify the material model post peak behavior. These changes reveal an overall improvement of the Finite Element (FE) model's ability to predict experimental results. First, the steel projectile is modeled using Johnson-Cook material model and provides a more realistic behavior in the FE ballistic models. This is particularly noticeable when comparing FE models with laboratory tests where large deformations in projectiles are observed. Second, follow-up analysis of the results obtained through the new picture frame tests conducted at ASU provides new values for the shear moduli and corresponding strains. The new approach for analysis of data from picture frame tests combines digital image analysis and a two-level factorial optimization formulation. Finally, an additional improvement in the material model for Kevlar involves checking the convergence at variation of mesh density of fabrics. The study performed and described herein shows the converging trend, therefore validating the FE model.
Constitutive Autophagy and Nucleophagy during Epidermal Differentiation.
Akinduro, Olufolake; Sully, Katherine; Patel, Ankit; Robinson, Deborah J; Chikh, Anissa; McPhail, Graham; Braun, Kristin M; Philpott, Michael P; Harwood, Catherine A; Byrne, Carolyn; O'Shaughnessy, Ryan F L; Bergamaschi, Daniele
2016-07-01
Epidermal keratinocytes migrate through the epidermis up to the granular layer where, on terminal differentiation, they progressively lose organelles and convert into anucleate cells or corneocytes. Our report explores the role of autophagy in ensuring epidermal function providing the first comprehensive profile of autophagy marker expression in developing epidermis. We show that autophagy is constitutively active in the epidermal granular layer where by electron microscopy we identified double-membrane autophagosomes. We demonstrate that differentiating keratinocytes undergo a selective form of nucleophagy characterized by accumulation of microtubule-associated protein light chain 3/lysosomal-associated membrane protein 2/p62 positive autolysosomes. These perinuclear vesicles displayed positivity for histone interacting protein, heterochromatin protein 1α, and localize in proximity with Lamin A and B1 accumulation, whereas in newborn mice and adult human skin, we report LC3 puncta coincident with misshaped nuclei within the granular layer. This process relies on autophagy integrity as confirmed by lack of nucleophagy in differentiating keratinocytes depleted from WD repeat domain phosphoinositide interacting 1 or Unc-51 like autophagy activating kinase 1. Final validation into a skin disease model showed that impaired autophagy contributes to the pathogenesis of psoriasis. Lack of LC3 expression in psoriatic skin lesions correlates with parakeratosis and deregulated expression or location of most of the autophagic markers. Our findings may have implications and improve treatment options for patients with epidermal barrier defects. PMID:27021405
Health Care for Micronesians and Constitutional Rights
Shek, Dina
2011-01-01
Under the Compacts of Free Association (COFA), people from the Freely Associated States — the Republic of Palau (ROP), the Republic of the Marshall Islands (RMI), and the Federated States of Micronesia (FSM) — have been migrating to the United States in increasing numbers. In 1996, Congress passed broad welfare reform (Personal Responsibility and Work Opportunity Reconciliation Act) which limited certain federal benefits previously available to COFA migrants, including Medicaid benefits. Prior to July 2010, the State of Hawai‘i had continued to include COFA migrants under its state-funded Medicaid program. In the face of budget constraints, the State removed these people from its Medicaid rolls. A challenge on the legal basis of the denial of equal protection of the laws, ie, the Fourteenth Amendment to the US Constitution, was successful in reinstating health care to the COFA migrants in December 2010. From the health worker's perspective, regardless of various social justice arguments that may have been marshaled in favor of delivering health care to the people, it was an appeal to the judicial system that succeeded. From the attorney's perspective, the legal victories are potentially limited to the four walls of the courtroom without community involvement and related social justice movements. Together, the authors propose that in order to better address the issue of health care access for Micronesian peoples, we must work together, as health and legal advocates, to define a more robust vision of both systems that includes reconciliation and community engagement. PMID:22235150
Yagi, M.; Horton, W. )
1994-07-01
A set of reduced Braginskii equations is derived without assuming flute ordering and the Boussinesq approximation. These model equations conserve the physical energy. It is crucial at finite [beta] that the perpendicular component of Ohm's law be solved to ensure [del][center dot][bold j]=0 for energy conservation.
Uniqueness of Maxwell's Equations.
ERIC Educational Resources Information Center
Cohn, Jack
1978-01-01
Shows that, as a consequence of two feasible assumptions and when due attention is given to the definition of charge and the fields E and B, the lowest-order equations that these two fields must satisfy are Maxwell's equations. (Author/GA)
Octonic Massive Field Equations
NASA Astrophysics Data System (ADS)
Demir, Süleyman; Kekeç, Seray
2016-07-01
In the present paper we propose the octonic form of massive field equations based on the analogy with electromagnetism and linear gravity. Using the advantages of octon algebra the Maxwell-Dirac-Proca equations have been reformulated in compact and elegant way. The energy-momentum relations for massive field are discussed.
NASA Astrophysics Data System (ADS)
Rossani, A.
2016-11-01
If electrons (e) and holes (h) in metals or semiconductors are heated to the temperatures Te and Th greater than the lattice temperature Tp, the electron-phonon interaction causes energy relaxation. In the nonuniform case, a momentum relaxation occurs as well. In view of such an application, a new model based on an asymptotic procedure for solving the kinetic equations of carriers and phonons is proposed, with generation-recombination of electrons and holes, which gives naturally the displaced Maxwellian at the leading order. After that, balance equations for the electron number, hole number, energy densities, and momentum densities are constructed, which constitute now a system of eight equations for the chemical potentials (carriers), the temperatures (carriers and phonons), and the drift velocities (carriers and phonons). In the drift-diffusion approximation the constitutive laws are derived and the Onsager relations recovered.
From hyperbolic regularization to exact hydrodynamics for linearized Grad's equations.
Colangeli, Matteo; Karlin, Iliya V; Kröger, Martin
2007-05-01
Inspired by a recent hyperbolic regularization of Burnett's hydrodynamic equations [A. Bobylev, J. Stat. Phys. 124, 371 (2006)], we introduce a method to derive hyperbolic equations of linear hydrodynamics to any desired accuracy in Knudsen number. The approach is based on a dynamic invariance principle which derives exact constitutive relations for the stress tensor and heat flux, and a transformation which renders the exact equations of hydrodynamics hyperbolic and stable. The method is described in detail for a simple kinetic model -- a 13 moment Grad system.
Zhang, Lei; Feng, Xiao; Wang, Xin; Liu, Changyong
2014-01-01
The nitrogen-containing austenitic stainless steel 316LN has been chosen as the material for nuclear main-pipe, which is one of the key parts in 3rd generation nuclear power plants. In this research, a constitutive model of nitrogen-containing austenitic stainless steel is developed. The true stress-true strain curves obtained from isothermal hot compression tests over a wide range of temperatures (900-1250°C) and strain rates (10(-3)-10 s(-1)), were employed to study the dynamic deformational behavior of and recrystallization in 316LN steels. The constitutive model is developed through multiple linear regressions performed on the experimental data and based on an Arrhenius-type equation and Zener-Hollomon theory. The influence of strain was incorporated in the developed constitutive equation by considering the effect of strain on the various material constants. The reliability and accuracy of the model is verified through the comparison of predicted flow stress curves and experimental curves. Possible reasons for deviation are also discussed based on the characteristics of modeling process.
Zhang, Lei; Feng, Xiao; Wang, Xin; Liu, Changyong
2014-01-01
The nitrogen-containing austenitic stainless steel 316LN has been chosen as the material for nuclear main-pipe, which is one of the key parts in 3rd generation nuclear power plants. In this research, a constitutive model of nitrogen-containing austenitic stainless steel is developed. The true stress-true strain curves obtained from isothermal hot compression tests over a wide range of temperatures (900–1250°C) and strain rates (10−3–10 s−1), were employed to study the dynamic deformational behavior of and recrystallization in 316LN steels. The constitutive model is developed through multiple linear regressions performed on the experimental data and based on an Arrhenius-type equation and Zener-Hollomon theory. The influence of strain was incorporated in the developed constitutive equation by considering the effect of strain on the various material constants. The reliability and accuracy of the model is verified through the comparison of predicted flow stress curves and experimental curves. Possible reasons for deviation are also discussed based on the characteristics of modeling process. PMID:25375345
Viscoelastic flow modeling in the extrusion of a dough-like fluid
NASA Technical Reports Server (NTRS)
Dhanasekharan, M.; Kokini, J. L.; Janes, H. W. (Principal Investigator)
2000-01-01
This work attempts to investigate the effect of viscoelasticity and three-dimensional geometry in screw channels. The Phan-Thien Tanner (PTT) constitutive equation with simplified model parameters was solved in conjunction with the flow equations. Polyflow, a commercially available finite element code was used to solve the resulting nonlinear partial differential equations. The PTT model predicted one log scale lower pressure buildup compared to the equivalent Newtonian results. However, the velocity profile did not show significant changes for the chosen PTT model parameters. Past Researchers neglected viscoelastic effects and also the three dimensional nature of the flow in extruder channels. The results of this paper provide a starting point for further simulations using more realistic model parameters, which may enable the food engineer to more accurately scale-up and design extrusion processes.
Viscoelastic flow modeling in the extrusion of a dough-like fluid.
Dhanasekharan, M; Kokini, J L
2000-08-01
This work attempts to investigate the effect of viscoelasticity and three-dimensional geometry in screw channels. The Phan-Thien Tanner (PTT) constitutive equation with simplified model parameters was solved in conjunction with the flow equations. Polyflow, a commercially available finite element code was used to solve the resulting nonlinear partial differential equations. The PTT model predicted one log scale lower pressure buildup compared to the equivalent Newtonian results. However, the velocity profile did not show significant changes for the chosen PTT model parameters. Past Researchers neglected viscoelastic effects and also the three dimensional nature of the flow in extruder channels. The results of this paper provide a starting point for further simulations using more realistic model parameters, which may enable the food engineer to more accurately scale-up and design extrusion processes.
How Does Astronomy Constitute A Learning Community?
NASA Astrophysics Data System (ADS)
Dogan, Yasemin; Sengul, R.; Unat, O.; Aknil, A.; Gurel, Z.
2010-01-01
This study was conducted in Turkey within an interdisciplinary project called "From a windowless home to a skyscraper: Let's build a home". It was realized through collaboration between a public university and a private high school. Researchers from Physics Education Department and volunteer teachers from high school, each studying on a different discipline, and volunteer high school students, all from an urban area of the country, conducted the project in a rural small town with resident secondary school students. It was implemented on the basis of history, through the use of different fields such as science, mathematics, geography, art, handcraft, architecture, engineering and astronomy in August 2008. The purpose of this study was to present the effect of the astronomical activities involved in the project. These implementations constructed a scientific and social base for the framework of astronomical activities of IYA2009, including building an amateur observatory. Since today's people are not so much acquainted with the issues of space and astronomy as much as the people of Antiquity, we attached special importance to the efforts in this field. The project, proceeded by a preparatory and informative period, involved night sky observation, initially with naked eye, followed by observation through telescope. Not only the students but also countless people, old or young, participated in our work in the field of astronomy. It provided a chance for all the people participating in or connected to the project to discover the sky. Astronomical activities aroused curiosity among students and the community and made a difference by inducing an awareness of the sky. The participants of the study had completely different social and cultural backgrounds, and this study removed all these differences bringing them together under the overarching astronomical and historical aspect. Moreover the community revealed all the characteristics that constitute a learning community.
How Does Astronomy Constitute a Learning Community?
NASA Astrophysics Data System (ADS)
Dogan, Yasemin; Sengul, R.; Unat, O.; Aknil, A.; Gurel, Z.
2009-05-01
This study was conducted in Turkey within an interdisciplinary project called "From a windowless home to a skyscraper: Let's build a home". It was realized through collaboration between a public university and a private high school. Researchers from Physics Education Department and volunteer teachers from high school, each studying on a different discipline, and volunteer high school students, all from an urban area of the country, conducted the project in a rural small town with resident secondary school students. It was implemented on the basis of history, through the use of different fields such as science, mathematics, geography, art, handcraft, architecture, engineering and astronomy in August 2008. The purpose of this study was to present the effect of the astronomical activities involved in the project. Since today's people are not so much acquainted with the issues of space and astronomy as much as the people of Antiquity, we attached special importance to the efforts in this field. The project, proceeded by a preparatory and informative period, involved night sky observation, initially with naked eye, followed by observation through a telescope. Not only the students but also countless people, old or young, participated in our work in the field of astronomy. It provided a chance for all the people participating in or connected to the project to discover the sky. Astronomical activities aroused curiosity among students and the community and made a difference by inducing an awareness of the sky. The participants of the study had completely different social and cultural backgrounds, and this study removed all these differences bringing them together under the overarching astronomical and historical aspect. Moreover the community revealed all the characteristics that constitute a learning community.
The normative constitution of professional power.
Frankford, D M
1997-02-01
This article concerns the manner in which we think and talk about power in health care policy and regulation, and the political and social practices allied with that discourse. I assert that in health care policy and practice we speak of and live within the era of countervailing power. In this language and practice power is a force exercised by one actor to enforce its will against another actor against whom power is exerted. I contend that this language inculcates an individual and social passivity in which citizens rely upon various types of representatives to constitute health care for them in a manner in which they do not and cannot participate. However, this language of power and the political and social practice with which it is associated is merely a contingent, historical product. I claim that an alternative discourse of power is possible, in which power consists of the social interactions in which all of us mutually participate but no one of us can control. Power in this sense is participatory by nature, and because no one is in control, it makes no sense to relegate tasks to specialized, nonparticipatory domains. This alternative discourse of power, therefore, might call forth participatory practices in health care and a concomitant diminution of specialization and expansion of the public sphere. The result would be to blur the lines separating politics from everyday interaction, politics from economy, professionals from patients, and insurers from insureds. Participation would mean much more than casting a vote or writing a check but would also include the mutual sharing of time and energy in the tasks that need to be done: long-term and short-term care, practices of prevention, caring for the chronically ill, and monitoring bureaucratic and professional activities. PMID:9057126
NASA Astrophysics Data System (ADS)
Kuksin, Sergei; Maiocchi, Alberto
In this chapter we present a general method of constructing the effective equation which describes the behavior of small-amplitude solutions for a nonlinear PDE in finite volume, provided that the linear part of the equation is a hamiltonian system with a pure imaginary discrete spectrum. The effective equation is obtained by retaining only the resonant terms of the nonlinearity (which may be hamiltonian, or may be not); the assertion that it describes the limiting behavior of small-amplitude solutions is a rigorous mathematical theorem. In particular, the method applies to the three- and four-wave systems. We demonstrate that different possible types of energy transport are covered by this method, depending on whether the set of resonances splits into finite clusters (this happens, e.g. in case of the Charney-Hasegawa-Mima equation), or is connected (this happens, e.g. in the case of the NLS equation if the space-dimension is at least two). For equations of the first type the energy transition to high frequencies does not hold, while for equations of the second type it may take place. Our method applies to various weakly nonlinear wave systems, appearing in plasma, meteorology and oceanography.
Nonlinear gyrokinetic equations
Dubin, D.H.E.; Krommes, J.A.; Oberman, C.; Lee, W.W.
1983-03-01
Nonlinear gyrokinetic equations are derived from a systematic Hamiltonian theory. The derivation employs Lie transforms and a noncanonical perturbation theory first used by Littlejohn for the simpler problem of asymptotically small gyroradius. For definiteness, we emphasize the limit of electrostatic fluctuations in slab geometry; however, there is a straight-forward generalization to arbitrary field geometry and electromagnetic perturbations. An energy invariant for the nonlinear system is derived, and various of its limits are considered. The weak turbulence theory of the equations is examined. In particular, the wave kinetic equation of Galeev and Sagdeev is derived from an asystematic truncation of the equations, implying that this equation fails to consider all gyrokinetic effects. The equations are simplified for the case of small but finite gyroradius and put in a form suitable for efficient computer simulation. Although it is possible to derive the Terry-Horton and Hasegawa-Mima equations as limiting cases of our theory, several new nonlinear terms absent from conventional theories appear and are discussed.
Nonlinear ordinary difference equations
NASA Technical Reports Server (NTRS)
Caughey, T. K.
1979-01-01
Future space vehicles will be relatively large and flexible, and active control will be necessary to maintain geometrical configuration. While the stresses and strains in these space vehicles are not expected to be excessively large, their cumulative effects will cause significant geometrical nonlinearities to appear in the equations of motion, in addition to the nonlinearities caused by material properties. Since the only effective tool for the analysis of such large complex structures is the digital computer, it will be necessary to gain a better understanding of the nonlinear ordinary difference equations which result from the time discretization of the semidiscrete equations of motion for such structures.
NASA Astrophysics Data System (ADS)
Pierret, Frédéric
2016-02-01
We derived the equations of Celestial Mechanics governing the variation of the orbital elements under a stochastic perturbation, thereby generalizing the classical Gauss equations. Explicit formulas are given for the semimajor axis, the eccentricity, the inclination, the longitude of the ascending node, the pericenter angle, and the mean anomaly, which are expressed in term of the angular momentum vector H per unit of mass and the energy E per unit of mass. Together, these formulas are called the stochastic Gauss equations, and they are illustrated numerically on an example from satellite dynamics.
Stochastic fuzzy differential equations of a nonincreasing type
NASA Astrophysics Data System (ADS)
Malinowski, Marek T.
2016-04-01
Stochastic fuzzy differential equations constitute an apparatus in modeling dynamic systems operating in fuzzy environment and governed by stochastic noises. In this paper we introduce a new kind of such the equations. Namely, the stochastic fuzzy differential of nonincreasing type are considered. The fuzzy stochastic processes which are solutions to these equations have trajectories with nonincreasing fuzziness in their values. In our previous papers, as a first natural extension of crisp stochastic differential equations, stochastic fuzzy differential equations of nondecreasing type were studied. In this paper we show that under suitable conditions each of the equations has a unique solution which possesses property of continuous dependence on data of the equation. To prove existence of the solutions we use sequences of successive approximate solutions. An estimation of an error of the approximate solution is established as well. Some examples of equations are solved and their solutions are simulated to illustrate the theory of stochastic fuzzy differential equations. All the achieved results apply to stochastic set-valued differential equations.
Constitutive laws in liquid-fluidized beds
NASA Astrophysics Data System (ADS)
Duru, Paul; Nicolas, Maxime; Hinch, John; Guazzelli, Élisabeth
2002-02-01
The objective of the present work is to test experimentally the two-phase modelling approach which is widely used in fluidization. A difficulty of this way of modelling fluidized beds is the use of empirical relations in order to close the system of equations describing the fluidized bed as a two-phase continuum, especially concerning the description of the solid phase. We performed an experimental investigation of the primary wavy instability of liquid-fluidized beds. Experiments demonstrate that the wave amplitude saturates up the bed and we were able to measure the precise shape of this voidage wave. We then related this shape to the unknown solid phase viscosity and pressure functions of a simple two-phase model with a Newtonian stress-tensor for the solid phase. We found the scaling laws and the particle concentration dependence for these two quantities. It appears that this simplest model is quite satisfactory to describe the one-dimensional voidage waves in the limited range of parameters that we have studied. In our experimental conditions, the drag on the particles nearly balances their weight corrected for buoyancy, the small imbalance being mostly accounted for by solid phase viscous stress with a much smaller contribution from the solid phase pressure.
Federal Register 2010, 2011, 2012, 2013, 2014
2012-10-16
... Energy Regulatory Commission Constitution Pipeline Company, LLC; Notice of Public Scoping Meeting and Extension of Scoping Period for the Planned Constitution Pipeline Project On October 24, 2012, the Federal... Constitution Pipeline Company's (Constitution) Constitution Pipeline Project. This notice also extends...
A Constitutive Model of 6111-T4 Aluminum Alloy Sheet Based on the Warm Tensile Test
NASA Astrophysics Data System (ADS)
Hua, Lin; Meng, Fanzhi; Song, Yanli; Liu, Jianing; Qin, Xunpeng; Suo, Lianbing
2014-03-01
As main light-weight material, aluminum alloy sheets have been widely applied to produce auto body panels. In order to predict the formability and springback of aluminum alloy sheets, a precise constitutive model is a necessity. In this article, a series of warm tensile tests were conducted on Gleeble-1500D thermal mechanical simulator for 6111-T4 aluminum alloy sheets. The corresponding strain rate ranged from 0.015 to 1.5 s-1, and the temperature ranged from 25 to 350 °C. The relationship between the temperature, the strain rate, and the flow stress were discussed. A constitutive model based on the updated Fields-Backofen equation was established to describe the flow behavior of 6111-T4 aluminum alloy during the warm tensile tests. Subsequently, the average absolute relative error (AARE) was introduced to verify the predictability of the constitutive model. The value of AARE at the uniform plastic deformation stage was calculated to be 1.677%, which demonstrates that the predicted flow stress values were in accordance with the experimental ones. The constitutive model was validated by the fact that the simulated results of the warm tensile tests coincided with the experimental ones.
What constitutes our understanding of a patient?
Chessick, R D
1993-01-01
aspects of prevailing ideologies in constituting and determining what we call truth and understanding, including the "understanding" of a patient in psychotherapy. An example of the postmodern blend of philosophy and psychoanalysis is presented by Arlow's emphasis on unconscious fantasies and his insightful comments on how these unconscious fantasies organize and determine what we experience from the very beginning of life. This I believe is most consistent with Rescher's philosophical notion of "conceptual idealism," also briefly reviewed in this paper.(ABSTRACT TRUNCATED AT 400 WORDS)
Nonlinear differential equations
Dresner, L.
1988-01-01
This report is the text of a graduate course on nonlinear differential equations given by the author at the University of Wisconsin-Madison during the summer of 1987. The topics covered are: direction fields of first-order differential equations; the Lie (group) theory of ordinary differential equations; similarity solutions of second-order partial differential equations; maximum principles and differential inequalities; monotone operators and iteration; complementary variational principles; and stability of numerical methods. The report should be of interest to graduate students, faculty, and practicing scientists and engineers. No prior knowledge is required beyond a good working knowledge of the calculus. The emphasis is on practical results. Most of the illustrative examples are taken from the fields of nonlinear diffusion, heat and mass transfer, applied superconductivity, and helium cryogenics.
Relativistic Guiding Center Equations
White, R. B.; Gobbin, M.
2014-10-01
In toroidal fusion devices it is relatively easy that electrons achieve relativistic velocities, so to simulate runaway electrons and other high energy phenomena a nonrelativistic guiding center formalism is not sufficient. Relativistic guiding center equations including flute mode time dependent field perturbations are derived. The same variables as used in a previous nonrelativistic guiding center code are adopted, so that a straightforward modifications of those equations can produce a relativistic version.
SIMULTANEOUS DIFFERENTIAL EQUATION COMPUTER
Collier, D.M.; Meeks, L.A.; Palmer, J.P.
1960-05-10
A description is given for an electronic simulator for a system of simultaneous differential equations, including nonlinear equations. As a specific example, a homogeneous nuclear reactor system including a reactor fluid, heat exchanger, and a steam boiler may be simulated, with the nonlinearity resulting from a consideration of temperature effects taken into account. The simulator includes three operational amplifiers, a multiplier, appropriate potential sources, and interconnecting R-C networks.
Jing, Xufeng; Xia, Rui; Wang, Weimin; Tian, Ying; Hong, Zhi
2016-05-01
We propose analytical expressions to determine the effective constitutive parameters of a planar bianisotropic metamaterial from scattering parameters in the terahertz region. In our retrieval method, the transmission and reflection coefficients in only one wave propagation direction are applied. Considering the nonsymmetry of planar metamaterials in the wave propagation direction, the effective refractive index and the impedance should be obtained by a modified S parameters retrieval process. The effective parameters of the permittivity, permeability, and magnetoelectric coupling coefficient of planar bianisotropic metamaterials can be retrieved by derived equations. Specifically, the constitutive parameters for different planar metamaterials, among which two are isotropic and the other two are bianisotropic metamaterials, are determined. The intrinsic differences between the normal planar metamaterials and the bianisotropic metamaterials are evidently illustrated. The phenomenon including electric coupling to magnetic resonance and only electric response in the transmission spectrum is confirmed by retrieval effective permittivity and permeability.
Can the Abraham Light Momentum and Energy in a Medium Constitute a Lorentz Four-Vector?
NASA Astrophysics Data System (ADS)
Wang, Changbiao
2013-08-01
By analyzing the Einstein-box thought experiment with the principle of relativity, it is shown that Abraham's light momentum and energy in a medium cannot constitute a Lorentz four-vector, and they consequentially break global momentum and energy conservation laws. In contrast, Minkowski's momentum and energy always constitute a Lorentz four-vector no matter whether in a medium or in vacuum, and the Minkowski's momentum is the unique correct light momentum. A momentum-associated photon mass in a medium is exposed, which explains why only the Abraham's momentum is derived in the traditional "center-of-mass-energy" approach. The EM boundary-condition matching approach, combined with Einstein light-quantum hypothesis, is proposed to analyze this thought experiment, and it is found for the first time that only from Maxwell equations without resort to the relativity, the correctness of light momentum definitions cannot be identified. Optical pulling effect is studied as well.
Set Equation Transformation System.
2002-03-22
Version 00 SETS is used for symbolic manipulation of Boolean equations, particularly the reduction of equations by the application of Boolean identities. It is a flexible and efficient tool for performing probabilistic risk analysis (PRA), vital area analysis, and common cause analysis. The equation manipulation capabilities of SETS can also be used to analyze noncoherent fault trees and determine prime implicants of Boolean functions, to verify circuit design implementation, to determine minimum cost fire protectionmore » requirements for nuclear reactor plants, to obtain solutions to combinatorial optimization problems with Boolean constraints, and to determine the susceptibility of a facility to unauthorized access through nullification of sensors in its protection system. Two auxiliary programs, SEP and FTD, are included. SEP performs the quantitative analysis of reduced Boolean equations (minimal cut sets) produced by SETS. The user can manipulate and evaluate the equations to find the probability of occurrence of any desired event and to produce an importance ranking of the terms and events in an equation. FTD is a fault tree drawing program which uses the proprietary ISSCO DISSPLA graphics software to produce an annotated drawing of a fault tree processed by SETS. The DISSPLA routines are not included.« less
Equation of state of polytetrafluoroethylene
NASA Astrophysics Data System (ADS)
Bourne, N. K.; Gray, G. T.
2003-06-01
The present drive to make munitions as safe as is feasible and to develop predictive models describing their constitutive response, has led to the development and production of plastic bonded explosives and propellants. There is a range of elastomers used as binder materials with the energetic components. One of these is known as Kel-F-800™ (poly-chloro-trifluroethylene) whose structure is in some ways analogous to that of poly-tetrafluoroethylene (PTFE or Teflon). Thus, it is of interest to assess the mechanical behavior of Teflon and to compare the response of five different production Teflon materials, two of which were produced in pedigree form, one as-received product, and two from previous in-depth literature studies. The equations of state of these variants were quantified by conducting a series of shock impact experiments in which both pressure-particle velocity and shock velocity-particle velocity dependencies were measured. The compressive behavior of Teflon, based upon the results of this study, appears to be independent of the production route and additives introduced.
Study Guide for the United States Constitution and Teacher's Manual.
ERIC Educational Resources Information Center
Hagemann, Frances L.
Presented in this document are a student's study guide and an accompanying teacher's manual. The purpose of the study guide is to present information on (1) what the U.S. Constitution means, (2) how the U.S. government is organized, (3) why the Constitution is a living document, and (4) why the Constitution is a source of pride for U.S. citizens.…
Nonlinear Constitutive Relations for High Temperature Application, 1984
NASA Technical Reports Server (NTRS)
1985-01-01
Nonlinear constitutive relations for high temperature applications were discussed. The state of the art in nonlinear constitutive modeling of high temperature materials was reviewed and the need for future research and development efforts in this area was identified. Considerable research efforts are urgently needed in the development of nonlinear constitutive relations for high temperature applications prompted by recent advances in high temperature materials technology and new demands on material and component performance. Topics discussed include: constitutive modeling, numerical methods, material testing, and structural applications.
A constitutive model for the forces of a magnetic bearing including eddy currents
NASA Technical Reports Server (NTRS)
Taylor, D. L.; Hebbale, K. V.
1993-01-01
A multiple magnet bearing can be developed from N individual electromagnets. The constitutive relationships for a single magnet in such a bearing is presented. Analytical expressions are developed for a magnet with poles arranged circumferencially. Maxwell's field equations are used so the model easily includes the effects of induced eddy currents due to the rotation of the journal. Eddy currents must be included in any dynamic model because they are the only speed dependent parameter and may lead to a critical speed for the bearing. The model is applicable to bearings using attraction or repulsion.
NASA Astrophysics Data System (ADS)
Sarbandi, B.; Besson, J.; Boussuge, M.; Ryckelynck, D.
2010-06-01
Slip cast ceramic components undergo both sintering shrinkage and creep deformation caused by gravity during the firing cycle. In addition sintering may be anisotropic due to the development of preferential directions during slip casting. Both phenomena induce complex deformations of parts which make the design of casting molds difficult. To help solving this problem, anisotropic constitutive equations are proposed to represent the behavior of the ceramic compacts during sintering. The model parameters are identified using tests allowing to characterize both sintering and creep. The model was implemented in a finite element software and used to simulate the deformation of a traditional ceramic object during sintering.
Sarbandi, B.; Besson, J.; Boussuge, M.; Ryckelynck, D.
2010-06-15
Slip cast ceramic components undergo both sintering shrinkage and creep deformation caused by gravity during the firing cycle. In addition sintering may be anisotropic due to the development of preferential directions during slip casting. Both phenomena induce complex deformations of parts which make the design of casting molds difficult. To help solving this problem, anisotropic constitutive equations are proposed to represent the behavior of the ceramic compacts during sintering. The model parameters are identified using tests allowing to characterize both sintering and creep. The model was implemented in a finite element software and used to simulate the deformation of a traditional ceramic object during sintering.
Introducing Chemical Formulae and Equations.
ERIC Educational Resources Information Center
Dawson, Chris; Rowell, Jack
1979-01-01
Discusses when the writing of chemical formula and equations can be introduced in the school science curriculum. Also presents ways in which formulae and equations learning can be aided and some examples for balancing and interpreting equations. (HM)
The Bernoulli-Poiseuille Equation.
ERIC Educational Resources Information Center
Badeer, Henry S.; Synolakis, Costas E.
1989-01-01
Describes Bernoulli's equation and Poiseuille's equation for fluid dynamics. Discusses the application of the combined Bernoulli-Poiseuille equation in real flows, such as viscous flows under gravity and acceleration. (YP)
Parallel tridiagonal equation solvers
NASA Technical Reports Server (NTRS)
Stone, H. S.
1974-01-01
Three parallel algorithms were compared for the direct solution of tridiagonal linear systems of equations. The algorithms are suitable for computers such as ILLIAC 4 and CDC STAR. For array computers similar to ILLIAC 4, cyclic odd-even reduction has the least operation count for highly structured sets of equations, and recursive doubling has the least count for relatively unstructured sets of equations. Since the difference in operation counts for these two algorithms is not substantial, their relative running times may be more related to overhead operations, which are not measured in this paper. The third algorithm, based on Buneman's Poisson solver, has more arithmetic operations than the others, and appears to be the least favorable. For pipeline computers similar to CDC STAR, cyclic odd-even reduction appears to be the most preferable algorithm for all cases.
Nonlocal electrical diffusion equation
NASA Astrophysics Data System (ADS)
Gómez-Aguilar, J. F.; Escobar-Jiménez, R. F.; Olivares-Peregrino, V. H.; Benavides-Cruz, M.; Calderón-Ramón, C.
2016-07-01
In this paper, we present an analysis and modeling of the electrical diffusion equation using the fractional calculus approach. This alternative representation for the current density is expressed in terms of the Caputo derivatives, the order for the space domain is 0<β≤1 and for the time domain is 0<γ≤2. We present solutions for the full fractional equation involving space and time fractional derivatives using numerical methods based on Fourier variable separation. The case with spatial fractional derivatives leads to Levy flight type phenomena, while the time fractional equation is related to sub- or super diffusion. We show that the mathematical concept of fractional derivatives can be useful to understand the behavior of semiconductors, the design of solar panels, electrochemical phenomena and the description of anomalous complex processes.
Cheng, Jui-Fen; Liu, Te-Le; Wang, Ruey-Yun; Ching, Han-Yi
2016-01-01
Objective. To explore the relationship between body constitution (BC) types and weight change in patients with schizophrenia and who underwent second-generation antipsychotics (SGAs) treatment. Method. Body weight and waist circumference of eighty-five participants were measured for 6 consecutive weeks. Constitutions of Yin-Xu, Yang-Xu, and Stasis were assessed using the Body Constitution Questionnaire (BCQ). Results. Participants with body constitutions Yin-Xu (50.6%), Yang-Xu (49.4%), or Stasis (38.8%) exhibited worse physical condition and unhealthy daily habits, particularly in Stasis constitution. Moreover, Stasis constitution was significantly associated with several factors, including BMI, body weight, waist circumference, perception of stress, perception of health, staying up late, and less physical exercise. However, perception of stress showed significant difference in Yin-Xu, Yang-Xu, and Stasis. Generalized estimating equation (GEE) analysis revealed that significant time effects in body weight increase in the imbalanced BC types and gentleness BC type. SGAs induced weight gain in imbalanced BC type as well as gentleness BC type, especially treated with olanzapine. Conclusions. This is the first study to explore the longitudinal relationship between BC and weight gain in schizophrenia patients undergoing SGAs treatment. Health care providers should focus on weight gain problems in schizophrenia patients who underwent SGAs treatment.
Stochastic differential equations
Sobczyk, K. )
1990-01-01
This book provides a unified treatment of both regular (or random) and Ito stochastic differential equations. It focuses on solution methods, including some developed only recently. Applications are discussed, in particular an insight is given into both the mathematical structure, and the most efficient solution methods (analytical as well as numerical). Starting from basic notions and results of the theory of stochastic processes and stochastic calculus (including Ito's stochastic integral), many principal mathematical problems and results related to stochastic differential equations are expounded here for the first time. Applications treated include those relating to road vehicles, earthquake excitations and offshore structures.
NASA Technical Reports Server (NTRS)
Markley, F. Landis
1995-01-01
Kepler's Equation is solved over the entire range of elliptic motion by a fifth-order refinement of the solution of a cubic equation. This method is not iterative, and requires only four transcendental function evaluations: a square root, a cube root, and two trigonometric functions. The maximum relative error of the algorithm is less than one part in 10(exp 18), exceeding the capability of double-precision computer arithmetic. Roundoff errors in double-precision implementation of the algorithm are addressed, and procedures to avoid them are developed.
Teaching about the U.S. Constitution. A Resource Packet.
ERIC Educational Resources Information Center
Leming, Robert S.; And Others
The 200th anniversary of the United States Constitution offers an excellent opportunity for encouraging renewed study of the principles and foundations of constitutional government. This resource packet provides a listing of current materials and resources to aid teachers in planning lesson units. The listings include: (1) professional…
Counting for Representation: The Census and the Constitution.
ERIC Educational Resources Information Center
Bureau of the Census (DOC), Suitland, MD.
The census is even more important today than it was 200 years ago. The census is taken to provide equal representation for everyone, and results provide figures for appointment and the distribution of federal funds. The enumeration of the population was included in the U.S. Constitution in Article I, Section 2. The constitutional order to…
This Constitution: A Bicentennial Chronicle, Nos. 14-18.
ERIC Educational Resources Information Center
Mann, Shelia, Ed.
1987-01-01
Each issue in this bicentennial series features articles on selected U.S. Constitution topics, along with a section on primary documents and lesson plans or class activities. Issue 14 features: (1) "The Political Economy of the Constitution" (K. Dolbeare; L. Medcalf); (2) "A 'New Historical Whooper': Creating the Art of the Constitutional…
The American Solution: Origins of the United States Constitution.
ERIC Educational Resources Information Center
Rutland, Robert A.
Tracing the history of events that led to the U.S. Constitutional Convention (1787) and to the eventual ratification of the U.S. Constitution, this book presents numerous reproductions of leaders' portraits, documents, and paintings from the U.S. Library of Congress and other collections. Chapter 1, "Was the Revolution a Blessing or a Curse?"…
27 CFR 19.512 - Bottles not constituting approved containers.
Code of Federal Regulations, 2011 CFR
2011-04-01
... 27 Alcohol, Tobacco Products and Firearms 1 2011-04-01 2011-04-01 false Bottles not constituting... AND TRADE BUREAU, DEPARTMENT OF THE TREASURY LIQUORS DISTILLED SPIRITS PLANTS Liquor Bottle, Label, and Closure Requirements Authorized Liquor Bottles § 19.512 Bottles not constituting...
27 CFR 26.316 - Bottles not constituting approved containers.
Code of Federal Regulations, 2011 CFR
2011-04-01
... 27 Alcohol, Tobacco Products and Firearms 1 2011-04-01 2011-04-01 false Bottles not constituting... VIRGIN ISLANDS Requirements for Liquor Bottles § 26.316 Bottles not constituting approved containers. The appropriate TTB officer is authorized to disapprove any bottle, including a bottle of less than 200...
27 CFR 27.206 - Bottles not constituting approved containers.
Code of Federal Regulations, 2010 CFR
2010-04-01
... 27 Alcohol, Tobacco Products and Firearms 1 2010-04-01 2010-04-01 false Bottles not constituting... Requirements for Liquor Bottles § 27.206 Bottles not constituting approved containers. The appropriate TTB officer is authorized to disapprove any bottle, including a bottle of less than 200 ml. capacity, for...
27 CFR 26.316 - Bottles not constituting approved containers.
Code of Federal Regulations, 2010 CFR
2010-04-01
... 27 Alcohol, Tobacco Products and Firearms 1 2010-04-01 2010-04-01 false Bottles not constituting... VIRGIN ISLANDS Requirements for Liquor Bottles § 26.316 Bottles not constituting approved containers. The appropriate TTB officer is authorized to disapprove any bottle, including a bottle of less than 200...
27 CFR 27.206 - Bottles not constituting approved containers.
Code of Federal Regulations, 2011 CFR
2011-04-01
... 27 Alcohol, Tobacco Products and Firearms 1 2011-04-01 2011-04-01 false Bottles not constituting... Requirements for Liquor Bottles § 27.206 Bottles not constituting approved containers. The appropriate TTB officer is authorized to disapprove any bottle, including a bottle of less than 200 ml. capacity, for...
Helping Children To Understand the United States Constitution.
ERIC Educational Resources Information Center
Novick, Minna S.
Targeted for children aged 5 through 12, this handbook contains some ideas for educational activities, a brief overview of the constitutional development period in U.S. history, and a simplified annotated outline of the Constitution. This material should prove helpful in teaching children the following: (1) the intrinsic values embedded in the…
[Teaching Materials about the U.S. Constitution.
ERIC Educational Resources Information Center
Commission on the Bicentennial of the United States Constitution, Washington, DC.
Issued by the Commission on the Bicentennial of the United States Constitution, this collection of instructional materials is designed to help teach about the United States Constitution. The documents include: "Plant a Living Legacy"; "Teaching Guide to Accompany United States Presidents, 1789-1989"; "Skills Handbook: 200 Years of the U.S.…
Guidelines for Teaching and Testing the Illinois Constitution.
ERIC Educational Resources Information Center
Illinois State Office of the Superintendent of Public Instruction, Springfield. Instructional Services Unit.
This document sets forth guidelines for teaching and testing public school students on the principles of democratic government as expressed in the Constitution of the United States and the Constitution of the State of Illinois. Identification is made of ways of making the examination required by the state of Illinois not only an integral part of…
Constitutionality of Compulsory Arbitration Statutes in Public Employment
ERIC Educational Resources Information Center
Staudohar, Paul D.
1976-01-01
Reviews state supreme court rulings on constitutionality issues raised by compulsory arbitration for public employees. Cases are reviewed for the states of Wyoming, Pennsylvania, Rhode Island, Nebraska, Maine, Michigan, New York, South Dakota, Oklahoma, and Washington. Concludes that courts have generally upheld the constitutionality of such…
Equality: Constitutional Update. Bar/School Partnership Programs Series.
ERIC Educational Resources Information Center
American Bar Association, Chicago, IL. Special Committee on Youth Education for Citizenship.
The second in a special four-part series of law-school partnership handbooks on constitutional themes, this document focuses on equality. "Equality--the Forgotten Word" (J. A. Hughes) discusses what has been considered the U.S. Constitution's one flaw, its failure to abolish slavery, and the remedy to that flaw, the Fourteenth Amendment. The issue…
Educational Research as a Reflexive Science of Constitution
ERIC Educational Resources Information Center
Packer, Martin
2010-01-01
"Constitution" is a relationship of mutual formation between people and their form of life. Neither can exist without the other. In the 1970s, proposals were made in various social sciences, including anthropology, political science, and sociology, for a new kind of inquiry that would focus squarely on constitution. It would be an explicitly…
Elevation view of one of the doorways on the Constitution ...
Elevation view of one of the doorways on the Constitution Avenue side of the building; the door is flanked by monumental neoclassical urns carved from granite - United States Department of Commerce, Bounded by Fourteenth, Fifteenth, and E streets and Constitution Avenue, Washington, District of Columbia, DC
What Constitution Day Means and Why It Matters
ERIC Educational Resources Information Center
Jamieson, Kathleen Hall
2014-01-01
For almost three quarters of a century, advocates have worked to give comparable federal stature to September 17, the day on which we celebrate the anniversary of the 1787 signing of the U.S. Constitution by the nation's founders. As President John F. Kennedy noted in his 1961 Constitution Day proclamation, it is a day for…
Living Democracy: How Constitution High School Molds Better Citizens
ERIC Educational Resources Information Center
Brasof, Marc
2009-01-01
Philadelphia's Constitution High School (CHS) is committed both to the theory of education for democracy, and to its practice, as reflected by a school constitution, student elections, town hall meetings, and active student participation in school government. As its name indicates, CHS is a theme-based high school that focuses on history,…
Perspective view of the south elevation; this facade faces Constitution ...
Perspective view of the south elevation; this facade faces Constitution Avenue and is nineteen bays long with twelve single columns and two sets of paired columns - United States Department of Commerce, Bounded by Fourteenth, Fifteenth, and E streets and Constitution Avenue, Washington, District of Columbia, DC
The Constitutionality of School Choice in New Hampshire
ERIC Educational Resources Information Center
Douglas, Charles G., III; Komer, Richard D.
2004-01-01
Does a "school choice" program, under which state funds are disbursed on a neutral basis to parents in the form of a voucher to defray the cost of sending their children to a school of their choice, run afoul of the Establishment Clause of the First Amendment to the United States Constitution, or of the New Hampshire Constitution? No. A school…
Equality v. Liberty v. Pluralism: Latinos in American Constitutional Law.
ERIC Educational Resources Information Center
Soltero, Carlos R.
This paper examines how U.S. courts, particularly the Supreme Court, have applied constitutional law principles to Latino communities and individuals in three areas: public education, the status of Puerto Rico, and jury selection. Consistent with traditional views of American society as biracial (black and white), constitutional law discussions…
Review of Resources: Teaching Law and the Constitution.
ERIC Educational Resources Information Center
Glade, Mary Elizabeth, Ed.
This guide provides analyses of curriculum materials that have been designed for teaching about the U.S. Constitution and law-related education. The guide begins with an editor's introduction and two essays, "Constitution Study and Civic Education" (James B. Giese) and "Thinking about Law-Related Education during the Bicentennial" (Barbara…
Constitutionalism and Republicanism in the American Founding: 1776-1787.
ERIC Educational Resources Information Center
Dry, Murray
1986-01-01
Illustrates the development of constitutionalism and republicanism from 1776 to 1787. Discusses the Declaration of Independence, arguments leading up to the Revolution, framing of the Constitution based on compromise, and opposing views of the ratification debate, all of which reveal disagreements over the precise meaning of republicanism. (TRS)
Teaching about the Constitution. NCSS Bulletin No. 80.
ERIC Educational Resources Information Center
Keller, Clair W., Ed.; Schillings, Denny L., Ed.
This book provides a historical perspective on the changing nature of the United States Constitution and the society it has shaped. Part I focuses on the eighteenth century with chapters on the origins, writing, and ratification of the Constitution. Activities are designed to help students think about the difficulties associated with the creation…
The Constitutionality of Racial Classifications in Public School Admissions.
ERIC Educational Resources Information Center
Brown, Kevin
2000-01-01
Revisits the Supreme Court's school desegregation jurisprudence, examining the typical analysis applied to this issue by recent lower federal court decisions. Discusses Supreme Court cases applying constitutional provisions to the public education context, suggesting that the constitutional analysis of the use of racial classifications to further…
Initiative for the Bicentennial of the U.S. Constitution.
ERIC Educational Resources Information Center
National Endowment for the Humanities (NFAH), Washington, DC.
The 200th anniversary of the United States Constitution offers a singular occasion for encouraging renewed scholarly interest in and public reflection about the principles and foundations of constitutional government. Toward that end, this publication presents categories and guidelines within each of the National Endowment for the Humanities…
29 CFR 452.109 - Constitution of labor organization.
Code of Federal Regulations, 2011 CFR
2011-07-01
... insofar as they are not inconsistent with the provisions of title IV. 53 53 Act, sec. 401(e). Under 29 CFR... 29 Labor 2 2011-07-01 2011-07-01 false Constitution of labor organization. 452.109 Section 452.109... AND DISCLOSURE ACT OF 1959 Election Procedures; Rights of Members § 452.109 Constitution of...
29 CFR 452.109 - Constitution of labor organization.
Code of Federal Regulations, 2014 CFR
2014-07-01
... insofar as they are not inconsistent with the provisions of title IV. 53 53 Act, sec. 401(e). Under 29 CFR... 29 Labor 2 2014-07-01 2014-07-01 false Constitution of labor organization. 452.109 Section 452.109... AND DISCLOSURE ACT OF 1959 Election Procedures; Rights of Members § 452.109 Constitution of...
29 CFR 452.109 - Constitution of labor organization.
Code of Federal Regulations, 2013 CFR
2013-07-01
... insofar as they are not inconsistent with the provisions of title IV. 53 53 Act, sec. 401(e). Under 29 CFR... 29 Labor 2 2013-07-01 2013-07-01 false Constitution of labor organization. 452.109 Section 452.109... AND DISCLOSURE ACT OF 1959 Election Procedures; Rights of Members § 452.109 Constitution of...
29 CFR 452.109 - Constitution of labor organization.
Code of Federal Regulations, 2012 CFR
2012-07-01
... insofar as they are not inconsistent with the provisions of title IV. 53 53 Act, sec. 401(e). Under 29 CFR... 29 Labor 2 2012-07-01 2012-07-01 false Constitution of labor organization. 452.109 Section 452.109... AND DISCLOSURE ACT OF 1959 Election Procedures; Rights of Members § 452.109 Constitution of...
29 CFR 452.109 - Constitution of labor organization.
Code of Federal Regulations, 2010 CFR
2010-07-01
... insofar as they are not inconsistent with the provisions of title IV. 53 53 Act, sec. 401(e). Under 29 CFR... 29 Labor 2 2010-07-01 2010-07-01 false Constitution of labor organization. 452.109 Section 452.109... AND DISCLOSURE ACT OF 1959 Election Procedures; Rights of Members § 452.109 Constitution of...
The Statistical Drake Equation
NASA Astrophysics Data System (ADS)
Maccone, Claudio
2010-12-01
We provide the statistical generalization of the Drake equation. From a simple product of seven positive numbers, the Drake equation is now turned into the product of seven positive random variables. We call this "the Statistical Drake Equation". The mathematical consequences of this transformation are then derived. The proof of our results is based on the Central Limit Theorem (CLT) of Statistics. In loose terms, the CLT states that the sum of any number of independent random variables, each of which may be ARBITRARILY distributed, approaches a Gaussian (i.e. normal) random variable. This is called the Lyapunov Form of the CLT, or the Lindeberg Form of the CLT, depending on the mathematical constraints assumed on the third moments of the various probability distributions. In conclusion, we show that: The new random variable N, yielding the number of communicating civilizations in the Galaxy, follows the LOGNORMAL distribution. Then, as a consequence, the mean value of this lognormal distribution is the ordinary N in the Drake equation. The standard deviation, mode, and all the moments of this lognormal N are also found. The seven factors in the ordinary Drake equation now become seven positive random variables. The probability distribution of each random variable may be ARBITRARY. The CLT in the so-called Lyapunov or Lindeberg forms (that both do not assume the factors to be identically distributed) allows for that. In other words, the CLT "translates" into our statistical Drake equation by allowing an arbitrary probability distribution for each factor. This is both physically realistic and practically very useful, of course. An application of our statistical Drake equation then follows. The (average) DISTANCE between any two neighboring and communicating civilizations in the Galaxy may be shown to be inversely proportional to the cubic root of N. Then, in our approach, this distance becomes a new random variable. We derive the relevant probability density
Comparison of Kernel Equating and Item Response Theory Equating Methods
ERIC Educational Resources Information Center
Meng, Yu
2012-01-01
The kernel method of test equating is a unified approach to test equating with some advantages over traditional equating methods. Therefore, it is important to evaluate in a comprehensive way the usefulness and appropriateness of the Kernel equating (KE) method, as well as its advantages and disadvantages compared with several popular item…
Accumulative Equating Error after a Chain of Linear Equatings
ERIC Educational Resources Information Center
Guo, Hongwen
2010-01-01
After many equatings have been conducted in a testing program, equating errors can accumulate to a degree that is not negligible compared to the standard error of measurement. In this paper, the author investigates the asymptotic accumulative standard error of equating (ASEE) for linear equating methods, including chained linear, Tucker, and…
Parallel Multigrid Equation Solver
2001-09-07
Prometheus is a fully parallel multigrid equation solver for matrices that arise in unstructured grid finite element applications. It includes a geometric and an algebraic multigrid method and has solved problems of up to 76 mullion degrees of feedom, problems in linear elasticity on the ASCI blue pacific and ASCI red machines.
Do Differential Equations Swing?
ERIC Educational Resources Information Center
Maruszewski, Richard F., Jr.
2006-01-01
One of the units of in a standard differential equations course is a discussion of the oscillatory motion of a spring and the associated material on forcing functions and resonance. During the presentation on practical resonance, the instructor may tell students that it is similar to when they take their siblings to the playground and help them on…
Modelling by Differential Equations
ERIC Educational Resources Information Center
Chaachoua, Hamid; Saglam, Ayse
2006-01-01
This paper aims to show the close relation between physics and mathematics taking into account especially the theory of differential equations. By analysing the problems posed by scientists in the seventeenth century, we note that physics is very important for the emergence of this theory. Taking into account this analysis, we show the…
ERIC Educational Resources Information Center
Fay, Temple H.
2010-01-01
Through numerical investigations, we study examples of the forced quadratic spring equation [image omitted]. By performing trial-and-error numerical experiments, we demonstrate the existence of stability boundaries in the phase plane indicating initial conditions yielding bounded solutions, investigate the resonance boundary in the [omega]…
Generalized reduced magnetohydrodynamic equations
Kruger, S.E.
1999-02-01
A new derivation of reduced magnetohydrodynamic (MHD) equations is presented. A multiple-time-scale expansion is employed. It has the advantage of clearly separating the three time scales of the problem associated with (1) MHD equilibrium, (2) fluctuations whose wave vector is aligned perpendicular to the magnetic field, and (3) those aligned parallel to the magnetic field. The derivation is carried out without relying on a large aspect ratio assumption; therefore this model can be applied to any general configuration. By accounting for the MHD equilibrium and constraints to eliminate the fast perpendicular waves, equations are derived to evolve scalar potential quantities on a time scale associated with the parallel wave vector (shear-Alfven wave time scale), which is the time scale of interest for MHD instability studies. Careful attention is given in the derivation to satisfy energy conservation and to have manifestly divergence-free magnetic fields to all orders in the expansion parameter. Additionally, neoclassical closures and equilibrium shear flow effects are easily accounted for in this model. Equations for the inner resistive layer are derived which reproduce the linear ideal and resistive stability criterion of Glasser, Greene, and Johnson. The equations have been programmed into a spectral initial value code and run with shear flow that is consistent with the equilibrium input into the code. Linear results of tearing modes with shear flow are presented which differentiate the effects of shear flow gradients in the layer with the effects of the shear flow decoupling multiple harmonics.
Structural Equation Model Trees
ERIC Educational Resources Information Center
Brandmaier, Andreas M.; von Oertzen, Timo; McArdle, John J.; Lindenberger, Ulman
2013-01-01
In the behavioral and social sciences, structural equation models (SEMs) have become widely accepted as a modeling tool for the relation between latent and observed variables. SEMs can be seen as a unification of several multivariate analysis techniques. SEM Trees combine the strengths of SEMs and the decision tree paradigm by building tree…
Central role of the observable electric potential in transport equations.
Garrido, J; Compañ, V; López, M L
2001-07-01
Nonequilibrium systems are usually studied in the framework of transport equations that involve the true electric potential (TEP), a nonobservable variable. Nevertheless another electric potential, the observable electric potential (OEP), may be defined to construct a useful set of transport equations. In this paper several basic characteristics of the OEP are deduced and emphasized: (i) the OEP distribution depends on thermodynamic state of the solution, (ii) the observable equations have a reference value for all other transport equations, (iii) the bridge that connects the OEP with a certain TEP is usually defined by the ion activity coefficient, (iv) the electric charge density is a nonobservable variable, and (v) the OEP formulation constitutes a natural model for studying the fluxes in membrane systems. PMID:11461346
Central role of the observable electric potential in transport equations.
Garrido, J; Compañ, V; López, M L
2001-07-01
Nonequilibrium systems are usually studied in the framework of transport equations that involve the true electric potential (TEP), a nonobservable variable. Nevertheless another electric potential, the observable electric potential (OEP), may be defined to construct a useful set of transport equations. In this paper several basic characteristics of the OEP are deduced and emphasized: (i) the OEP distribution depends on thermodynamic state of the solution, (ii) the observable equations have a reference value for all other transport equations, (iii) the bridge that connects the OEP with a certain TEP is usually defined by the ion activity coefficient, (iv) the electric charge density is a nonobservable variable, and (v) the OEP formulation constitutes a natural model for studying the fluxes in membrane systems.
NASA Astrophysics Data System (ADS)
Chakraborty, Debadi; Sader, John E.
2015-05-01
Simple bulk liquids such as water are commonly assumed to be Newtonian. While this assumption holds widely, the fluid-structure interaction of mechanical devices at nanometer scales can probe the intrinsic molecular relaxation processes in a surrounding liquid. This was recently demonstrated through measurement of the high frequency (20 GHz) linear mechanical vibrations of bipyramidal nanoparticles in simple liquids [Pelton et al., "Viscoelastic flows in simple liquids generated by vibrating nanostructures," Phys. Rev. Lett. 111, 244502 (2013)]. In this article, we review and critically assess the available constitutive equations for compressible viscoelastic flows in their linear limits—such models are required for analysis of the above-mentioned measurements. We show that previous models, with the exception of a very recent proposal, do not reproduce the required response at high frequency. We explain the physical origin of this recent model and show that it recovers all required features of a linear viscoelastic flow. This constitutive equation thus provides a rigorous foundation for the analysis of vibrating nanostructures in simple liquids. The utility of this model is demonstrated by solving the fluid-structure interaction of two common problems: (1) a sphere executing radial oscillations in liquid, which depends strongly on the liquid compressibility and (2) the extensional mode vibration of bipyramidal nanoparticles in liquid, where the effects of liquid compressibility are negligible. This highlights the importance of shear and compressional relaxation processes, as a function of flow geometry, and the impact of the shear and bulk viscosities on nanometer scale flows.
Genetic Approach to Elucidation of Sasang Constitutional Medicine
Kim, Bu-Yeo; Cha, Seongwon; Jin, Hee-Jeong
2009-01-01
Sasang Constitutional Medicine (SCM) offers a medical principle that classifies humans into four constitution groups and guides their treatment with constitution-matched medical assistance. The principle of this traditional medicine, although requires significant scientific support, appears to suggest a genetic influence on constitution type. The relative frequency of constitution types in a population, for instance, has remained relatively constant since Jema Lee first described them from his observations. In addition, the body compartment concept of SCM appears to be related to the anterio–posterior patterning of the embryonic gut and associated internal organs. This study describes the attributes of the constitution concept of SCM that can be interpreted in the language of genetics and current approaches to identity the genetic factors that make up the constitution. These efforts should make it possible to interpret the principle of this traditional medicine scientifically. Considering the recent trend in medicine that pursues individualized or tailored medical offerings, once SCM is proven to be explainable with scientific evidence, it will be able to contribute to and take a place in the rapidly evolving medicine environment. PMID:19745011
Individualized medicine, health medicine, and constitutional theory in Chinese medicine.
Wang, Qi
2012-03-01
The patterns of modern science and changes in the medical model can result in the transformation of the current state of individualized and health medicines into being the primary trend in medical development. Chinese and Western medical systems are dissimilar in terms of value orientations, thinking style, and research directions because of their different historical and cultural backgrounds. Individualized treatment in modern medicine is mainly established based on individual genome information and the differences in mononucleotide polymorphisms. However, such treatment method is expensive, creates an uncertain genetic marker, and leads to different result interpretations, among other problems. The Chinese constitutional theory developed in the 1970s expresses the principle behind Chinese health medicine and individual treatment and provides the corresponding methods. The Chinese constitutional theory divides the constitution of the Chinese population into nine categories based on established classification criteria. It promotes the study of the relationship of each constitution to diseases and Chinese medicine preparation toward adjusting the constitution and preventing diseases. The theory also provides methods and tools for individualized treatment. Constitution identification shows the direction and provides the core technology for the evaluation of the health status. By combining the developments in modern biotechnology, new diagnostic techniques and treatment models of constitution-differentiation, disease-differentiation, and syndrome-differentiation can be established for the development of individualized Chinese medicine treatment and health medicine for the international medical community.
A procedure for utilization of a damage-dependent constitutive model for laminated composites
NASA Technical Reports Server (NTRS)
Lo, David C.; Allen, David H.; Harris, Charles E.
1992-01-01
Described here is the procedure for utilizing a damage constitutive model to predict progressive damage growth in laminated composites. In this model, the effects of the internal damage are represented by strain-like second order tensorial damage variables and enter the analysis through damage dependent ply level and laminate level constitutive equations. The growth of matrix cracks due to fatigue loading is predicted by an experimentally based damage evolutionary relationship. This model is incorporated into a computer code called FLAMSTR. This code is capable of predicting the constitutive response and matrix crack damage accumulation in fatigue loaded laminated composites. The structure and usage of FLAMSTR are presented along with sample input and output files to assist the code user. As an example problem, an analysis of crossply laminates subjected to two stage fatigue loading was conducted and the resulting damage accumulation and stress redistribution were examined to determine the effect of variations in fatigue load amplitude applied during the first stage of the load history. It was found that the model predicts a significant loading history effect on damage evolution.
NASA Technical Reports Server (NTRS)
Ellis, J. R.
1988-01-01
Complex states of stress and strain are introduced into components during service in engineering applications. It follows that analysis of such components requires material descriptions, or constitutive theories, which reflect the tensorial nature of stress and strain. For applications involving stress levels above yield, the situation is more complex in that material response is both nonlinear and history dependent. This has led to the development of viscoplastic constitutive theories which introduce time by expressing the flow and evolutionary equation in the form of time derivatives. Models were developed here which can be used to analyze high temperature components manufactured from advanced composite materials. In parallel with these studies, effort was directed at developing multiaxial testing techniques to verify the various theories. Recent progress in the development of constitutive theories from both the theoretical and experimental viewpoints are outlined. One important aspect is that material descriptions for advanced composite materials which can be implemented in general purpose finite element codes and used for practical design are verified.
Brownian motion from Boltzmann's equation.
NASA Technical Reports Server (NTRS)
Montgomery, D.
1971-01-01
Two apparently disparate lines of inquiry in kinetic theory are shown to be equivalent: (1) Brownian motion as treated by the (stochastic) Langevin equation and Fokker-Planck equation; and (2) Boltzmann's equation. The method is to derive the kinetic equation for Brownian motion from the Boltzmann equation for a two-component neutral gas by a simultaneous expansion in the density and mass ratios.
Supersymmetric fifth order evolution equations
Tian, K.; Liu, Q. P.
2010-03-08
This paper considers supersymmetric fifth order evolution equations. Within the framework of symmetry approach, we give a list containing six equations, which are (potentially) integrable systems. Among these equations, the most interesting ones include a supersymmetric Sawada-Kotera equation and a novel supersymmetric fifth order KdV equation. For the latter, we supply some properties such as a Hamiltonian structures and a possible recursion operator.
Law & psychiatry: Does the constitution require an insanity defense?
Appelbaum, Paul S
2013-10-01
Idaho is one of four states that have abolished the insanity defense. Hence, John Delling, on trial for two murders in Idaho, was unable to plead insanity or to argue that he lacked intent to kill, the only available option under Idaho law. After being sentenced to life in prison without parole, Delling challenged the constitutionality of Idaho's law. The state's supreme court rejected his appeal, holding that--despite the long history of the insanity defense and its widespread acceptance--there was no constitutional right to an insanity defense. Delling's petition to the U.S. Supreme Court was turned away, leaving the constitutional status of the insanity defense uncertain.
Study on the Constitutive Model for Jointed Rock Mass
Xu, Qiang; Chen, Jianyun; Li, Jing; Zhao, Chunfeng; Yuan, Chenyang
2015-01-01
A new elasto-plastic constitutive model for jointed rock mass, which can consider the persistence ratio in different visual angle and anisotropic increase of plastic strain, is proposed. The proposed the yield strength criterion, which is anisotropic, is not only related to friction angle and cohesion of jointed rock masses at the visual angle but also related to the intersection angle between the visual angle and the directions of the principal stresses. Some numerical examples are given to analyze and verify the proposed constitutive model. The results show the proposed constitutive model has high precision to calculate displacement, stress and plastic strain and can be applied in engineering analysis. PMID:25885695
Constitutive heterochromatin: a surprising variety of expressed sequences.
Dimitri, Patrizio; Caizzi, Ruggiero; Giordano, Ennio; Carmela Accardo, Maria; Lattanzi, Giovanna; Biamonti, Giuseppe
2009-08-01
The organization of chromosomes into euchromatin and heterochromatin is amongst the most important and enigmatic aspects of genome evolution. Constitutive heterochromatin is a basic yet still poorly understood component of eukaryotic chromosomes, and its molecular characterization by means of standard genomic approaches is intrinsically difficult. Although recent evidence indicates that the presence of transcribed genes in constitutive heterochromatin is a conserved trait that accompanies the evolution of eukaryotic genomes, the term heterochromatin is still considered by many as synonymous of gene silencing. In this paper, we comprehensively review data that provide a clearer picture of transcribed sequences within constitutive heterochromatin, with a special emphasis on Drosophila and humans.
Volume transport and generalized hydrodynamic equations for monatomic fluids.
Eu, Byung Chan
2008-10-01
In this paper, the effects of volume transport on the generalized hydrodynamic equations for a pure simple fluid are examined from the standpoint of statistical mechanics and, in particular, kinetic theory of fluids. First, we derive the generalized hydrodynamic equations, namely, the constitutive equations for the stress tensor and heat flux for a single-component monatomic fluid, from the generalized Boltzmann equation in the presence of volume transport. Then their linear steady-state solutions are derived and examined with regard to the effects of volume transport on them. The generalized hydrodynamic equations and linear constitutive relations obtained for nonconserved variables make it possible to assess Brenner's proposition [Physica A 349, 11 (2005); Physica A 349, 60 (2005)] for volume transport and attendant mass and volume velocities as well as the effects of volume transport on the Newtonian law of viscosity, compression/dilatation (bulk viscosity) phenomena, and Fourier's law of heat conduction. On the basis of study made, it is concluded that the notion of volume transport is sufficiently significant to retain in irreversible thermodynamics of fluids and fluid mechanics.
Deriving the time-independent Schrödinger equation
NASA Astrophysics Data System (ADS)
Gorard, Jonathan
2016-11-01
A discussion of the physical meaning of the Schrödinger wave equation can not only constitute an exciting introduction to some of the more abstract ideas of quantum mechanics, but serves more generally as a useful demonstration of the application of mathematics to modern physics. This frontline uses physical concepts and mathematical techniques that would be accessible to a sufficiently interested secondary school student, in order to derive the simplest, one-dimensional case of the time-independent Schrödinger equation: the derivation relies only upon aspects of Newtonian/wave mechanics, quantum theory, complex numbers and calculus that would be covered in an advanced secondary school syllabus.
The Bernoulli equation in a moving reference frame
NASA Astrophysics Data System (ADS)
Mungan, Carl E.
2011-03-01
Unlike other standard equations in introductory classical mechanics, the Bernoulli equation is not Galilean invariant. The explanation is that, in a reference frame moving with respect to constrictions or obstacles, those surfaces do work on the fluid, constituting an extra term that needs to be included in the work-energy calculation. A quantitative example is presented here for a horizontal tapered pipe. A frame-independent expression for the pressure drop in the pipe is obtained. The concepts discussed in this paper are accessible to introductory undergraduate physics majors.
Nikolaevskiy equation with dispersion.
Simbawa, Eman; Matthews, Paul C; Cox, Stephen M
2010-03-01
The Nikolaevskiy equation was originally proposed as a model for seismic waves and is also a model for a wide variety of systems incorporating a neutral "Goldstone" mode, including electroconvection and reaction-diffusion systems. It is known to exhibit chaotic dynamics at the onset of pattern formation, at least when the dispersive terms in the equation are suppressed, as is commonly the practice in previous analyses. In this paper, the effects of reinstating the dispersive terms are examined. It is shown that such terms can stabilize some of the spatially periodic traveling waves; this allows us to study the loss of stability and transition to chaos of the waves. The secondary stability diagram ("Busse balloon") for the traveling waves can be remarkably complicated. PMID:20365845
Causal electromagnetic interaction equations
Zinoviev, Yury M.
2011-02-15
For the electromagnetic interaction of two particles the relativistic causal quantum mechanics equations are proposed. These equations are solved for the case when the second particle moves freely. The initial wave functions are supposed to be smooth and rapidly decreasing at the infinity. This condition is important for the convergence of the integrals similar to the integrals of quantum electrodynamics. We also consider the singular initial wave functions in the particular case when the second particle mass is equal to zero. The discrete energy spectrum of the first particle wave function is defined by the initial wave function of the free-moving second particle. Choosing the initial wave functions of the free-moving second particle it is possible to obtain a practically arbitrary discrete energy spectrum.
A Generalization of the Einstein-Maxwell Equations
NASA Astrophysics Data System (ADS)
Cotton, Fredrick
2016-03-01
The proposed modifications of the Einstein-Maxwell equations include: (1) the addition of a scalar term to the electromagnetic side of the equation rather than to the gravitational side, (2) the introduction of a 4-dimensional, nonlinear electromagnetic constitutive tensor and (3) the addition of curvature terms arising from the non-metric components of a general symmetric connection. The scalar term is defined by the condition that a spherically symmetric particle be force-free and mathematically well-behaved everywhere. The constitutive tensor introduces two auxiliary fields which describe the particle structure. The additional curvature terms couple both to particle solutions and to electromagnetic and gravitational wave solutions. http://sites.google.com/site/fwcotton/em-30.pdf
Generalized reduced MHD equations
Kruger, S.E.; Hegna, C.C.; Callen, J.D.
1998-07-01
A new derivation of reduced magnetohydrodynamic (MHD) equations is presented. A multiple-time-scale expansion is employed. It has the advantage of clearly separating the three time scales of the problem associated with (1) MHD equilibrium, (2) fluctuations whose wave vector is aligned perpendicular to the magnetic field, and (3) those aligned parallel to the magnetic field. The derivation is carried out without relying on a large aspect ratio assumption; therefore this model can be applied to any general toroidal configuration. By accounting for the MHD equilibrium and constraints to eliminate the fast perpendicular waves, equations are derived to evolve scalar potential quantities on a time scale associated with the parallel wave vector (shear-alfven wave time scale), which is the time scale of interest for MHD instability studies. Careful attention is given in the derivation to satisfy energy conservation and to have manifestly divergence-free magnetic fields to all orders in the expansion parameter. Additionally, neoclassical closures and equilibrium shear flow effects are easily accounted for in this model. Equations for the inner resistive layer are derived which reproduce the linear ideal and resistive stability criterion of Glasser, Greene, and Johnson.
NASA Astrophysics Data System (ADS)
Konesky, Gregory
2009-08-01
In the almost half century since the Drake Equation was first conceived, a number of profound discoveries have been made that require each of the seven variables of this equation to be reconsidered. The discovery of hydrothermal vents on the ocean floor, for example, as well as the ever-increasing extreme conditions in which life is found on Earth, suggest a much wider range of possible extraterrestrial habitats. The growing consensus that life originated very early in Earth's history also supports this suggestion. The discovery of exoplanets with a wide range of host star types, and attendant habitable zones, suggests that life may be possible in planetary systems with stars quite unlike our Sun. Stellar evolution also plays an important part in that habitable zones are mobile. The increasing brightness of our Sun over the next few billion years, will place the Earth well outside the present habitable zone, but will then encompass Mars, giving rise to the notion that some Drake Equation variables, such as the fraction of planets on which life emerges, may have multiple values.
Your Board Can Help Students Learn from Our Constitution's Bicentennial.
ERIC Educational Resources Information Center
Chmelynski, Carol C.
1987-01-01
The celebration of the bicentennial of the United States Constitution will begin Fall 1987 and last until 1991. Outlines the national programs, exhibitions and festivals, and curriculum materials available for educators on the bicentennial. (MD)
Celebrating the Constitution's 200th Birthday in Elementary School.
ERIC Educational Resources Information Center
Burger, Warren E.
1987-01-01
The former Chief Justice of the United States, Warren Burger, discusses his elementary school experience with a substitute teacher who taught the elements of government in her classroom. Includes discussion of programing on the bicentennial celebration of the Constitution. (MD)
Constitution. Signed and delivered--the rules in writing.
Walshe, Kieran
2008-07-24
The proposal tucked away in the Darzi report for an NHS constitution could be one of the most historic elements of the next stage review, limiting the health secretary's power and guaranteeing patient rights.
The principles and operating procedures for the National Environmental Laboratory Accreditation Conference (NELAC) are contained in the NELAC Constitution and Bylaws. The major portion of this document (standards) contains detailed requirements for accrediting environmental labo...
Constitutional Law: Right of Privacy--Possession of Marijuana
ERIC Educational Resources Information Center
Rohrer, David E.
1976-01-01
The Alaska Supreme Court in Ravin v. State accepted the defendant's contention that the prohibition of possession of marihuana infringed on his constitutional right to privacy. The significance of the case is discussed. (LBH)
NASA Astrophysics Data System (ADS)
Wang, Wei; Wang, Xuanping; Hu, Changxu
2014-11-01
The benchmark problem of planar contraction flow is often used to evaluate the stability of numerical algorithms and the predictability of viscoelastic constitutive models in predicting the rheological behavior of polymer fluids. In this paper, for the simulation of planar contraction flow, the single/simplified modified double convected Pom-Pom (S-MDCPP) model recently proposed is adopted, and in the frame of iterative stabilized fractional step algorithm, the discrete elastic viscous stress splitting (DEVSS) technique in combination with the streamline upwind Petrov-Galerkin (SUPG) method is taken to serve as a stable numerical solution scheme for the viscoelastic flow, where the equal low-order interpolations are applied to the independent solution variables by virtue of stabilized form of mass conservation equation constructed based-on the finite incremental calculus method. The comparison of rheological behaviors by S-MDCPP model with those by experiment results and DCPP model is taken on the aspects of the material functions of shear viscosities and uniaxial elongation viscosities, stresses fields through the way of flow induced birefringence in the planar contraction flow, with the aim of assessing the constitutive models. In addition, the effects of the constitutive parameters of the S-MDCPP model and Weissenberg number on the rheological behaviors of polymer melts are discussed, with the flow field responses such as velocity, pressure, stress components, and backbone stretch included. Through these comparative studies, the capabilities of the S-MDCPP constitutive model are justified for the applications in branched polymer melts characterizations and numerical modeling.
Coupled Hydro-Mechanical Constitutive Model for Vegetated Soils: Validation and Applications
NASA Astrophysics Data System (ADS)
Switala, Barbara Maria; Veenhof, Rick; Wu, Wei; Askarinejad, Amin
2016-04-01
It is well known, that presence of vegetation influences stability of the slope. However, the quantitative assessment of this contribution remains challenging. It is essential to develop a numerical model, which combines mechanical root reinforcement and root water uptake, and allows modelling rainfall induced landslides of vegetated slopes. Therefore a novel constitutive formulation is proposed, which is based on the modified Cam-clay model for unsaturated soils. Mechanical root reinforcement is modelled introducing a new constitutive parameter, which governs the evolution of the Cam-clay failure surface with the degree of root reinforcement. Evapotranspiration is modelled in terms of the root water uptake, defined as a sink term in the water flow continuity equation. The original concept is extended for different shapes of the root architecture in three dimensions, and combined with the mechanical model. The model is implemented in the research finite element code Comes-Geo, and in the commercial software Abaqus. The formulation is tested, performing a series of numerical examples, which allow validation of the concept. The direct shear test and the triaxial test are modelled in order to test the performance of the mechanical part of the model. In order to validate the hydrological part of the constitutive formulation, evapotranspiration from the vegetated box is simulated and compared with the experimental results. Obtained numerical results exhibit a good agreement with the experimental data. The implemented model is capable of reproducing results of basic geotechnical laboratory tests. Moreover, the constitutive formulation can be used to model rainfall induced landslides of vegetated slopes, taking into account the most important factors influencing the slope stability (root reinforcement and evapotranspiration).
Double-Plate Penetration Equations
NASA Technical Reports Server (NTRS)
Hayashida, K. B.; Robinson, J. H.
2000-01-01
This report compares seven double-plate penetration predictor equations for accuracy and effectiveness of a shield design. Three of the seven are the Johnson Space Center original, modified, and new Cour-Palais equations. The other four are the Nysmith, Lundeberg-Stern-Bristow, Burch, and Wilkinson equations. These equations, except the Wilkinson equation, were derived from test results, with the velocities ranging up to 8 km/sec. Spreadsheet software calculated the projectile diameters for various velocities for the different equations. The results were plotted on projectile diameter versus velocity graphs for the expected orbital debris impact velocities ranging from 2 to 15 km/sec. The new Cour-Palais double-plate penetration equation was compared to the modified Cour-Palais single-plate penetration equation. Then the predictions from each of the seven double-plate penetration equations were compared to each other for a chosen shield design. Finally, these results from the equations were compared with test results performed at the NASA Marshall Space Flight Center. Because the different equations predict a wide range of projectile diameters at any given velocity, it is very difficult to choose the "right" prediction equation for shield configurations other than those exactly used in the equations' development. Although developed for various materials, the penetration equations alone cannot be relied upon to accurately predict the effectiveness of a shield without using hypervelocity impact tests to verify the design.
A phenomenological constitutive model for low density polyurethane foams
Neilsen, M.K.; Morgan, H.S.; Krieg, R.D.
1987-04-01
Results from a series of hydrostatic and triaxial compression tests which were performed on polyurethane foams are presented in this report. These tests indicate that the volumetric and deviatoric parts of the foam behavior are strongly coupled. This coupling behavior could not be captured with any of several commonly used plasticity models. Thus, a new constitutive model was developed. This new model was based on a decomposition of the foam response into two parts: (1) response of the polymer skeleton, and (2) response of the air inside the cells. The air contribution was completely volumetric. The new constitutive model was implemented in two finite element codes, SANCHO and PRONTO. Results from a series of analyses completed with these codes indicated that the new constitutive model captured all of the foam behaviors that had been observed in the experiments. Finally, a typical dynamic problem was analyzed using the new constitutive model and other constitutive models to demonstrate differences between the models. Results from this series of analyses indicated that the new constitutive model generated displacement and acceleration predictions that were between predictions obtained using the other models. This result was expected. 9 refs., 45 figs., 4 tabs.
Reduction operators of Burgers equation
Pocheketa, Oleksandr A.; Popovych, Roman O.
2013-01-01
The solution of the problem on reduction operators and nonclassical reductions of the Burgers equation is systematically treated and completed. A new proof of the theorem on the special “no-go” case of regular reduction operators is presented, and the representation of the coefficients of operators in terms of solutions of the initial equation is constructed for this case. All possible nonclassical reductions of the Burgers equation to single ordinary differential equations are exhaustively described. Any Lie reduction of the Burgers equation proves to be equivalent via the Hopf–Cole transformation to a parameterized family of Lie reductions of the linear heat equation. PMID:23576819
New application to Riccati equation
NASA Astrophysics Data System (ADS)
Taogetusang; Sirendaoerji; Li, Shu-Min
2010-08-01
To seek new infinite sequence of exact solutions to nonlinear evolution equations, this paper gives the formula of nonlinear superposition of the solutions and Bäcklund transformation of Riccati equation. Based on the tanh-function expansion method and homogenous balance method, new infinite sequence of exact solutions to Zakharov-Kuznetsov equation, Karamoto-Sivashinsky equation and the set of (2+1)-dimensional asymmetric Nizhnik-Novikov-Veselov equations are obtained with the aid of symbolic computation system Mathematica. The method is of significance to construct infinite sequence exact solutions to other nonlinear evolution equations.
Sato, K; Yuan, X-F; Kawakatsu, T
2010-02-01
Numerous numerical and experimental evidence suggest that shear banding behavior looks like first-order phase transitions. In this paper, we demonstrate that this correspondence is actually established in the so-called non-local diffusive Johnson-Segalman model (the DJS model), a typical mechanical constitutive model that has been widely used for describing shear banding phenomena. In the neighborhood of the critical point, we apply the reduction procedure based on the center manifold theory to the governing equations of the DJS model. As a result, we obtain a time evolution equation of the flow field that is equivalent to the time-dependent Ginzburg-Landau (TDGL) equations for modeling thermodynamic first-order phase transitions. This result, for the first time, provides a mathematical proof that there is an analogy between the mechanical instability and thermodynamic phase transition at least in the vicinity of the critical point of the shear banding of DJS model. Within this framework, we can clearly distinguish the metastable branch in the stress-strain rate curve around the shear banding region from the globally stable branch. A simple extension of this analysis to a class of more general constitutive models is also discussed. Numerical simulations for the original DJS model and the reduced TDGL equation is performed to confirm the range of validity of our reduction theory.
Evaluating Equating Results: Percent Relative Error for Chained Kernel Equating
ERIC Educational Resources Information Center
Jiang, Yanlin; von Davier, Alina A.; Chen, Haiwen
2012-01-01
This article presents a method for evaluating equating results. Within the kernel equating framework, the percent relative error (PRE) for chained equipercentile equating was computed under the nonequivalent groups with anchor test (NEAT) design. The method was applied to two data sets to obtain the PRE, which can be used to measure equating…
Differential Equations Compatible with Boundary Rational qKZ Equation
NASA Astrophysics Data System (ADS)
Takeyama, Yoshihiro
2011-10-01
We give diffierential equations compatible with the rational qKZ equation with boundary reflection. The total system contains the trigonometric degeneration of the bispectral qKZ equation of type (Cěen, Cn) which in the case of type GLn was studied by van Meer and Stokman. We construct an integral formula for solutions to our compatible system in a special case.
The compressible adjoint equations in geodynamics: equations and numerical assessment
NASA Astrophysics Data System (ADS)
Ghelichkhan, Siavash; Bunge, Hans-Peter
2016-04-01
The adjoint method is a powerful means to obtain gradient information in a mantle convection model relative to past flow structure. While the adjoint equations in geodynamics have been derived for the conservation equations of mantle flow in their incompressible form, the applicability of this approximation to Earth is limited, because density increases by almost a factor of two from the surface to the Core Mantle Boundary. Here we introduce the compressible adjoint equations for the conservation equations in the anelastic-liquid approximation. Our derivation applies an operator formulation in Hilbert spaces, to connect to recent work in seismology (Fichtner et al (2006)) and geodynamics (Horbach et al (2014)), where the approach was used to derive the adjoint equations for the wave equation and incompressible mantle flow. We present numerical tests of the newly derived equations based on twin experiments, focusing on three simulations. A first, termed Compressible, assumes the compressible forward and adjoint equations, and represents the consistent means of including compressibility effects. A second, termed Mixed, applies the compressible forward equation, but ignores compressibility effects in the adjoint equations, where the incompressible equations are used instead. A third simulation, termed Incompressible, neglects compressibility effects entirely in the forward and adjoint equations relative to the reference twin. The compressible and mixed formulations successfully restore earlier mantle flow structure, while the incompressible formulation yields noticeable artifacts. Our results suggest the use of a compressible formulation, when applying the adjoint method to seismically derived mantle heterogeneity structure.
Estimating Equating Error in Observed-Score Equating. Research Report.
ERIC Educational Resources Information Center
van der Linden, Wim J.
Traditionally, error in equating observed scores on two versions of a test is defined as the difference between the transformations that equate the quantiles of their distributions in the sample and in the population of examinees. This definition underlies, for example, the well-known approximation to the standard error of equating by Lord (1982).…
NASA Astrophysics Data System (ADS)
Taff, L. G.; Brennan, T. A.
1989-06-01
Intrigued by the recent advances in research on solving Kepler's equation, we have attacked the problem too. Our contributions emphasize the unified derivation of all known bounds and several starting values, a proof of the optimality of these bounds, a very thorough numerical exploration of a large variety of starting values and solution techniques in both mean anomaly/eccentricity space and eccentric anomaly/eccentricity space, and finally the best and simplest starting value/solution algorithm: M + e and Wegstein's secant modification of the method of successive substitutions. The very close second is Broucke's bounds coupled with Newton's second-order scheme.
The Arrhenius equation revisited.
Peleg, Micha; Normand, Mark D; Corradini, Maria G
2012-01-01
The Arrhenius equation has been widely used as a model of the temperature effect on the rate of chemical reactions and biological processes in foods. Since the model requires that the rate increase monotonically with temperature, its applicability to enzymatic reactions and microbial growth, which have optimal temperature, is obviously limited. This is also true for microbial inactivation and chemical reactions that only start at an elevated temperature, and for complex processes and reactions that do not follow fixed order kinetics, that is, where the isothermal rate constant, however defined, is a function of both temperature and time. The linearity of the Arrhenius plot, that is, Ln[k(T)] vs. 1/T where T is in °K has been traditionally considered evidence of the model's validity. Consequently, the slope of the plot has been used to calculate the reaction or processes' "energy of activation," usually without independent verification. Many experimental and simulated rate constant vs. temperature relationships that yield linear Arrhenius plots can also be described by the simpler exponential model Ln[k(T)/k(T(reference))] = c(T-T(reference)). The use of the exponential model or similar empirical alternative would eliminate the confusing temperature axis inversion, the unnecessary compression of the temperature scale, and the need for kinetic assumptions that are hard to affirm in food systems. It would also eliminate the reference to the Universal gas constant in systems where a "mole" cannot be clearly identified. Unless proven otherwise by independent experiments, one cannot dismiss the notion that the apparent linearity of the Arrhenius plot in many food systems is due to a mathematical property of the model's equation rather than to the existence of a temperature independent "energy of activation." If T+273.16°C in the Arrhenius model's equation is replaced by T+b, where the numerical value of the arbitrary constant b is substantially larger than T and T
Makkonen, Lasse
2016-04-01
Young's construction for a contact angle at a three-phase intersection forms the basis of all fields of science that involve wetting and capillary action. We find compelling evidence from recent experimental results on the deformation of a soft solid at the contact line, and displacement of an elastic wire immersed in a liquid, that Young's equation can only be interpreted by surface energies, and not as a balance of surface tensions. It follows that the a priori variable in finding equilibrium is not the position of the contact line, but the contact angle. This finding provides the explanation for the pinning of a contact line. PMID:26940644
Behavioral momentum theory: equations and applications.
Nevin, John A; Shahan, Timothy A
2011-01-01
Behavioral momentum theory provides a quantitative account of how reinforcers experienced within a discriminative stimulus context govern the persistence of behavior that occurs in that context. The theory suggests that all reinforcers obtained in the presence of a discriminative stimulus increase resistance to change, regardless of whether those reinforcers are contingent on the target behavior, are noncontingent, or are even contingent on an alternative behavior. In this paper, we describe the equations that constitute the theory and address their application to issues of particular importance in applied settings. The theory provides a framework within which to consider the effects of interventions such as extinction, noncontingent reinforcement, differential reinforcement of alternative behavior, and other phenomena (e.g., resurgence). Finally, the theory predicts some counterintuitive and potentially counterproductive effects of alternative reinforcement, and can serve as an integrative guide for intervention when its terms are identified with the relevant conditions of applied settings.
A New Reynolds Stress Algebraic Equation Model
NASA Technical Reports Server (NTRS)
Shih, Tsan-Hsing; Zhu, Jiang; Lumley, John L.
1994-01-01
A general turbulent constitutive relation is directly applied to propose a new Reynolds stress algebraic equation model. In the development of this model, the constraints based on rapid distortion theory and realizability (i.e. the positivity of the normal Reynolds stresses and the Schwarz' inequality between turbulent velocity correlations) are imposed. Model coefficients are calibrated using well-studied basic flows such as homogeneous shear flow and the surface flow in the inertial sublayer. The performance of this model is then tested in complex turbulent flows including the separated flow over a backward-facing step and the flow in a confined jet. The calculation results are encouraging and point to the success of the present model in modeling turbulent flows with complex geometries.
Behavioral momentum theory: equations and applications.
Nevin, John A; Shahan, Timothy A
2011-01-01
Behavioral momentum theory provides a quantitative account of how reinforcers experienced within a discriminative stimulus context govern the persistence of behavior that occurs in that context. The theory suggests that all reinforcers obtained in the presence of a discriminative stimulus increase resistance to change, regardless of whether those reinforcers are contingent on the target behavior, are noncontingent, or are even contingent on an alternative behavior. In this paper, we describe the equations that constitute the theory and address their application to issues of particular importance in applied settings. The theory provides a framework within which to consider the effects of interventions such as extinction, noncontingent reinforcement, differential reinforcement of alternative behavior, and other phenomena (e.g., resurgence). Finally, the theory predicts some counterintuitive and potentially counterproductive effects of alternative reinforcement, and can serve as an integrative guide for intervention when its terms are identified with the relevant conditions of applied settings. PMID:22219536
Evaluation of potential crushed-salt constitutive models
Callahan, G.D.; Loken, M.C.; Sambeek, L.L. Van; Chen, R.; Pfeifle, T.W.; Nieland, J.D.
1995-12-01
Constitutive models describing the deformation of crushed salt are presented in this report. Ten constitutive models with potential to describe the phenomenological and micromechanical processes for crushed salt were selected from a literature search. Three of these ten constitutive models, termed Sjaardema-Krieg, Zeuch, and Spiers models, were adopted as candidate constitutive models. The candidate constitutive models were generalized in a consistent manner to three-dimensional states of stress and modified to include the effects of temperature, grain size, and moisture content. A database including hydrostatic consolidation and shear consolidation tests conducted on Waste Isolation Pilot Plant and southeastern New Mexico salt was used to determine material parameters for the candidate constitutive models. Nonlinear least-squares model fitting to data from the hydrostatic consolidation tests, the shear consolidation tests, and a combination of the shear and hydrostatic tests produces three sets of material parameter values for the candidate models. The change in material parameter values from test group to test group indicates the empirical nature of the models. To evaluate the predictive capability of the candidate models, each parameter value set was used to predict each of the tests in the database. Based on the fitting statistics and the ability of the models to predict the test data, the Spiers model appeared to perform slightly better than the other two candidate models. The work reported here is a first-of-its kind evaluation of constitutive models for reconsolidation of crushed salt. Questions remain to be answered. Deficiencies in models and databases are identified and recommendations for future work are made. 85 refs.
Conservational PDF Equations of Turbulence
NASA Technical Reports Server (NTRS)
Shih, Tsan-Hsing; Liu, Nan-Suey
2010-01-01
Recently we have revisited the traditional probability density function (PDF) equations for the velocity and species in turbulent incompressible flows. They are all unclosed due to the appearance of various conditional means which are modeled empirically. However, we have observed that it is possible to establish a closed velocity PDF equation and a closed joint velocity and species PDF equation through conditions derived from the integral form of the Navier-Stokes equations. Although, in theory, the resulted PDF equations are neither general nor unique, they nevertheless lead to the exact transport equations for the first moment as well as all higher order moments. We refer these PDF equations as the conservational PDF equations. This observation is worth further exploration for its validity and CFD application
Solitons and nonlinear wave equations
Dodd, Roger K.; Eilbeck, J. Chris; Gibbon, John D.; Morris, Hedley C.
1982-01-01
A discussion of the theory and applications of classical solitons is presented with a brief treatment of quantum mechanical effects which occur in particle physics and quantum field theory. The subjects addressed include: solitary waves and solitons, scattering transforms, the Schroedinger equation and the Korteweg-de Vries equation, and the inverse method for the isospectral Schroedinger equation and the general solution of the solvable nonlinear equations. Also considered are: isolation of the Korteweg-de Vries equation in some physical examples, the Zakharov-Shabat/AKNS inverse method, kinks and the sine-Gordon equation, the nonlinear Schroedinger equation and wave resonance interactions, amplitude equations in unstable systems, and numerical studies of solitons. 45 references.
Voutouri, Chrysovalantis; Mpekris, Fotios; Papageorgis, Panagiotis; Odysseos, Andreani D; Stylianopoulos, Triantafyllos
2014-01-01
Mechanical forces play a crucial role in tumor patho-physiology. Compression of cancer cells inhibits their proliferation rate, induces apoptosis and enhances their invasive and metastatic potential. Additionally, compression of intratumor blood vessels reduces the supply of oxygen, nutrients and drugs, affecting tumor progression and treatment. Despite the great importance of the mechanical microenvironment to the pathology of cancer, there are limited studies for the constitutive modeling and the mechanical properties of tumors and on how these parameters affect tumor growth. Also, the contribution of the host tissue to the growth and state of stress of the tumor remains unclear. To this end, we performed unconfined compression experiments in two tumor types and found that the experimental stress-strain response is better fitted to an exponential constitutive equation compared to the widely used neo-Hookean and Blatz-Ko models. Subsequently, we incorporated the constitutive equations along with the corresponding values of the mechanical properties - calculated by the fit - to a biomechanical model of tumor growth. Interestingly, we found that the evolution of stress and the growth rate of the tumor are independent from the selection of the constitutive equation, but depend strongly on the mechanical interactions with the surrounding host tissue. Particularly, model predictions - in agreement with experimental studies - suggest that the stiffness of solid tumors should exceed a critical value compared with that of the surrounding tissue in order to be able to displace the tissue and grow in size. With the use of the model, we estimated this critical value to be on the order of 1.5. Our results suggest that the direct effect of solid stress on tumor growth involves not only the inhibitory effect of stress on cancer cell proliferation and the induction of apoptosis, but also the resistance of the surrounding tissue to tumor expansion.
``Riemann equations'' in bidifferential calculus
NASA Astrophysics Data System (ADS)
Chvartatskyi, O.; Müller-Hoissen, F.; Stoilov, N.
2015-10-01
We consider equations that formally resemble a matrix Riemann (or Hopf) equation in the framework of bidifferential calculus. With different choices of a first-order bidifferential calculus, we obtain a variety of equations, including a semi-discrete and a fully discrete version of the matrix Riemann equation. A corresponding universal solution-generating method then either yields a (continuous or discrete) Cole-Hopf transformation, or leaves us with the problem of solving Riemann equations (hence an application of the hodograph method). If the bidifferential calculus extends to second order, solutions of a system of "Riemann equations" are also solutions of an equation that arises, on the universal level of bidifferential calculus, as an integrability condition. Depending on the choice of bidifferential calculus, the latter can represent a number of prominent integrable equations, like self-dual Yang-Mills, as well as matrix versions of the two-dimensional Toda lattice, Hirota's bilinear difference equation, (2+1)-dimensional Nonlinear Schrödinger (NLS), Kadomtsev-Petviashvili (KP) equation, and Davey-Stewartson equations. For all of them, a recent (non-isospectral) binary Darboux transformation result in bidifferential calculus applies, which can be specialized to generate solutions of the associated "Riemann equations." For the latter, we clarify the relation between these specialized binary Darboux transformations and the aforementioned solution-generating method. From (arbitrary size) matrix versions of the "Riemann equations" associated with an integrable equation, possessing a bidifferential calculus formulation, multi-soliton-type solutions of the latter can be generated. This includes "breaking" multi-soliton-type solutions of the self-dual Yang-Mills and the (2+1)-dimensional NLS equation, which are parametrized by solutions of Riemann equations.
Solving Nonlinear Coupled Differential Equations
NASA Technical Reports Server (NTRS)
Mitchell, L.; David, J.
1986-01-01
Harmonic balance method developed to obtain approximate steady-state solutions for nonlinear coupled ordinary differential equations. Method usable with transfer matrices commonly used to analyze shaft systems. Solution to nonlinear equation, with periodic forcing function represented as sum of series similar to Fourier series but with form of terms suggested by equation itself.
Successfully Transitioning to Linear Equations
ERIC Educational Resources Information Center
Colton, Connie; Smith, Wendy M.
2014-01-01
The Common Core State Standards for Mathematics (CCSSI 2010) asks students in as early as fourth grade to solve word problems using equations with variables. Equations studied at this level generate a single solution, such as the equation x + 10 = 25. For students in fifth grade, the Common Core standard for algebraic thinking expects them to…
The Forced Hard Spring Equation
ERIC Educational Resources Information Center
Fay, Temple H.
2006-01-01
Through numerical investigations, various examples of the Duffing type forced spring equation with epsilon positive, are studied. Since [epsilon] is positive, all solutions to the associated homogeneous equation are periodic and the same is true with the forcing applied. The damped equation exhibits steady state trajectories with the interesting…
Equating with Miditests Using IRT
ERIC Educational Resources Information Center
Fitzpatrick, Joseph; Skorupski, William P.
2016-01-01
The equating performance of two internal anchor test structures--miditests and minitests--is studied for four IRT equating methods using simulated data. Originally proposed by Sinharay and Holland, miditests are anchors that have the same mean difficulty as the overall test but less variance in item difficulties. Four popular IRT equating methods…
On stochastic diffusion equations and stochastic Burgers' equations
NASA Astrophysics Data System (ADS)
Truman, A.; Zhao, H. Z.
1996-01-01
In this paper we construct a strong solution for the stochastic Hamilton Jacobi equation by using stochastic classical mechanics before the caustics. We thereby obtain the viscosity solution for a certain class of inviscid stochastic Burgers' equations. This viscosity solution is not continuous beyond the caustics of the corresponding Hamilton Jacobi equation. The Hopf-Cole transformation is used to identify the stochastic heat equation and the viscous stochastic Burgers' equation. The exact solutions for the above two equations are given in terms of the stochastic Hamilton Jacobi function under a no-caustic condition. We construct the heat kernel for the stochastic heat equation for zero potentials in hyperbolic space and for harmonic oscillator potentials in Euclidean space thereby obtaining the stochastic Mehler formula.
Constitutive mutations in the Escherichia coli AraC protein.
Dirla, Stephanie; Chien, John Yeh-Heng; Schleif, Robert
2009-04-01
The Escherichia coli AraC protein represses and induces the araBAD operon in response to the absence or presence of l-arabinose. Constitutive mutations in the AraC gene no longer require the presence of l-arabinose to convert AraC from its repressing to its inducing state. Such mutations were isolated directly by virtue of their constitutivity or by their resistance to the nonmetabolizable arabinose analog, d-fucose. The majority of the constitutive mutations lie within the same residues of the N-terminal regulatory arm of AraC. Two, however, were found in the core of the dimerization domain. As predicted by the light switch mechanism of AraC, constitutive mutations increase the susceptibility of the N-terminal arms to digestion by trypsin or chymotrypsin, suggesting that these mutations weaken or disrupt the arm structure required for repression by AraC. Fluorescence, circular dichroism, and cysteine reactivity measurements show that the constitutive mutations in the core of the dimerization domain lead to a weakening of the support for the arms and reduce the stability of the minus-arabinose arm structure. These mutations also weaken the interaction between the two-helix bundle and the beta-barrel subdomains of the dimerization domain and reduce the structural stability of the beta-barrels.
Underground herbivory and the costs of constitutive defense in tobacco
NASA Astrophysics Data System (ADS)
Preisser, Evan L.; Gibson, Sarah E.; Adler, Lynn S.; Lewis, Edwin E.
2007-03-01
Nicotine is both a constitutive and induced defense in cultivated tobacco ( Nicotiana tabacum). Nicotine is thought primarily to defend against above-ground herbivory; however, below-ground herbivores like the nematode Meloidogyne incognita can also damage plants. We evaluated the costs and benefits of constitutive nicotine production in four near-isogenic lines of N. tabacum differing in nicotine content. We exposed the four lines to levels of nematode infection below that found to induce nicotine synthesis, and measured nematode density and each line's response to nematode presence. Nematode density did not differ among lines and was not related to leaf nicotine content in any of the lines, suggesting that constitutive nicotine content did not affect nematode survival or reproduction. Most measures of plant performance were unaffected by nematodes; however, nematode infection decreased flowering in the high nicotine line relative to the other lines. Lines with less constitutive nicotine did not incur similar costs, suggesting a tradeoff between nicotine production and tolerance of low levels of herbivory. A cost of nicotine production is also suggested by the fact that flowering was inversely correlated with leaf nicotine content in all four lines. Although nicotine conferred no resistance to nematodes, high nicotine content reduced the plant's tolerance of low levels of nematode infection and was correlated with reduced flowering. In examining the costs and benefits of a constitutive plant defense, this work complements and extends previous research addressing the relationship between plant tolerance and induced defenses.
Perspective of the human body in sasang constitutional medicine.
Lee, Junhee; Jung, Yongjae; Yoo, Junghee; Lee, Euiju; Koh, Byunghee
2009-09-01
The Sasang constitutional medicine (SCM), a medical tradition originating from Korea, is distinguished from the traditional Chinese medicine in its philosophical background, theoretical development and especially, the fundamental rationale that analyzes the structure and function of the human body within a quadrifocal scheme. In SCM, the structure of the body is comprehended within the Sasang quadrifocal scheme, and the function of the body is understood within the context of the energy-fluid metabolism and the water-food metabolism controlled by the four main organs (lung, spleen, liver and kidney). Also, the concept of Seong-Jeong is used to explain the structural and functional variations between different constitutional types that arise from the constitutional variations in organ system scheme, which are in turn caused by deviations in the constitutional Seong-Jeong. Therefore, understanding the SCM perspective of the human body is essential in order to fully appreciate the advantages of the constitutional typological system (which focuses on individual idiosyncrasies) found in SCM.
Choi, Jae-Ho; Chung, Mi Ja; Oh, Deog-Hwan
2012-09-01
Sasang is a Korean traditional constitutional medicine in which individuals are classified into four constitutional types: Taeyangin, Soeumin, Taeumin, and Soyangin. However, the classification of each constitution is empirical and not scientific, and so it is difficult to consistently classify patients into these four constitutional types. Acanthopanacis cortex (AC; Taeyangin), Rehmanniae radix (RR; Soyangin), Ephedra herba (EH; Taeumin), and White ginseng (WG; Soeumin) are herbal medicines that are used to treat and prevent diseases associated with these four constitutions. Therefore, AC, RR, EH, and WG extracts (ACE, RRE, EHE, and WGE) were used as reference extracts to determine constitutional differences in the immunostimulatory activities of primary immune cells isolated from the blood of 15 volunteers. Cellular proliferation, nitric oxide (NO), tumor necrosis factor-α (TNF-α) protein production, TNF-α and interleukin-6, and inducible NO synthase mRNA expression were measured as the immunostimulatory parameters. The increase in cell proliferation of V2, V3, V8, V11, and V12 was highest in EHE-treated lymphocytes among the ACE-, RRE-, EHE- or WGE-treated lymphocytes, and increase in cellular proliferation of V4, V7, V13, V14, and V15 in RRE-treated lymphocytes was significantly better than the other three medicines. The cell proliferation of V1, V5, V6, V9, and V10 responded best to WGE among the four extracts. Results of cell proliferation and other immunostimulatory parameters showed similar trends in regard to individual differences. These extracts may be useful as reference extracts in the development of a rapid and dependable individual lymphocyte- or macrophage-based assay that aids in the Sasang constitutional classification. PMID:22870991
New constitutionalism and the social reproduction of caring institutions.
Gill, Stephen; Bakker, Isabella
2006-01-01
This essay analyzes neo-liberal economic agreements and legal and political frameworks or what has been called the "new constitutionalism," a governance framework that empowers market forces to reshape economic and social development worldwide. The article highlights some consequences of new constitutionalism for caring institutions specifically, and for what feminists call social reproduction more generally: the biological reproduction of the species; the reproduction of labor power; and the reproduction of social institutions and processes associated with the creation and maintenance of communities. New constitutional governance frameworks fundamentally reshape conditions under which the care of human beings takes place. Caring institutions once governed by enabling professions geared to universal care are now determined increasingly by market values and private forces, and driven directly by the profit motive. This is one of the reasons why neo-liberalism is increasingly contested in both the North and the global South. PMID:16532302
Impact of season and constitution on lipid parameters.
Singh, Pramod Kumar; Byadgi, Parameswarappa S; Singh, Girish; Tripathi, Narendra Shanker
2013-01-01
Ayurveda prescribes daily and seasonal regimen in maintaining good health. Measures in the preservation of health have been described considering one's own Prakriti, Satva, Vayas, Bala, Agni, Ojus, season, and so on. Depending on the relative predominance of Doshas in various constitutions and seasons, certain regimens have been prescribed. The present study was done to assess the lipid profile in 54 healthy volunteers. It was observed from the present data that winter month is one of the potential risk factors for cardiovascular diseases because more lipid profile level was observed during winter. Among the constitutions, Kapha and Pitta Prakriti are more vulnerable for cardiovascular diseases because more lipid profile level is observed in these constitutions during winter. PMID:24049409
Exploring patients' rights: what does the NHS Constitution tell us?
McHale, Jean V
On 8 March 2012, the NHS published the latest version of its Constitution. In this article, the author explores the background of the debate regarding patients' rights and entitlements in the NHS. The author also discusses the provisions of the NHS Constitution, noting that it is largely a statement of existing principles, rather than a bold statement of rights. The paper suggests that, in some instances, its discussion of rights may suggest that patients have broader rights than may in fact be the case. The Constitution is currently under review, and the author recommends that the way forward for a society where the provision of care is likely to be more complex would be the introduction of a Patients' Rights Act.
New constitutionalism and the social reproduction of caring institutions.
Gill, Stephen; Bakker, Isabella
2006-01-01
This essay analyzes neo-liberal economic agreements and legal and political frameworks or what has been called the "new constitutionalism," a governance framework that empowers market forces to reshape economic and social development worldwide. The article highlights some consequences of new constitutionalism for caring institutions specifically, and for what feminists call social reproduction more generally: the biological reproduction of the species; the reproduction of labor power; and the reproduction of social institutions and processes associated with the creation and maintenance of communities. New constitutional governance frameworks fundamentally reshape conditions under which the care of human beings takes place. Caring institutions once governed by enabling professions geared to universal care are now determined increasingly by market values and private forces, and driven directly by the profit motive. This is one of the reasons why neo-liberalism is increasingly contested in both the North and the global South.
Requirements for energy based constitutive modeling in tire mechanics
NASA Technical Reports Server (NTRS)
Luchini, John R.; Peters, Jim M.; Mars, Will V.
1995-01-01
The history, requirements, and theoretical basis of a new energy based constitutive model for (rubber) material elasticity, hysteresis, and failure are presented. Energy based elasticity is handled by many constitutive models, both in one dimension and in three dimensions. Conversion of mechanical energy to heat can be modeled with viscoelasticity or as structural hysteresis. We are seeking unification of elasticity, hysteresis, and failure mechanisms such as fatigue and wear. An energy state characterization for failure criteria of (rubber) materials may provide this unification and also help explain the interaction of temperature effects with failure mechanisms which are described as creation of growth of internal crack surface. Improved structural modeling of tires with FEM should result from such a unified constitutive theory. The theory will also guide experimental work and should enable better interpretation of the results of computational stress analyses.
Generalized Klein-Kramers equations
NASA Astrophysics Data System (ADS)
Fa, Kwok Sau
2012-12-01
A generalized Klein-Kramers equation for a particle interacting with an external field is proposed. The equation generalizes the fractional Klein-Kramers equation introduced by Barkai and Silbey [J. Phys. Chem. B 104, 3866 (2000), 10.1021/jp993491m]. Besides, the generalized Klein-Kramers equation can also recover the integro-differential Klein-Kramers equation for continuous-time random walk; this means that it can describe the subdiffusive and superdiffusive regimes in the long-time limit. Moreover, analytic solutions for first two moments both in velocity and displacement (for force-free case) are obtained, and their dynamic behaviors are investigated.
Multinomial Diffusion Equation
Balter, Ariel I.; Tartakovsky, Alexandre M.
2011-06-01
We have developed a novel stochastic, space/time discrete representation of particle diffusion (e.g. Brownian motion) based on discrete probability distributions. We show that in the limit of both very small time step and large concentration, our description is equivalent to the space/time continuous stochastic diffusion equation. Being discrete in both time and space, our model can be used as an extremely accurate, efficient, and stable stochastic finite-difference diffusion algorithm when concentrations are so small that computationally expensive particle-based methods are usually needed. Through numerical simulations, we show that our method can generate realizations that capture the statistical properties of particle simulations. While our method converges converges to both the correct ensemble mean and ensemble variance very quickly with decreasing time step, but for small concentration, the stochastic diffusion PDE does not, even for very small time steps.
NASA Astrophysics Data System (ADS)
Cardona, Carlos; Gomez, Humberto
2016-06-01
Recently the CHY approach has been extended to one loop level using elliptic functions and modular forms over a Jacobian variety. Due to the difficulty in manipulating these kind of functions, we propose an alternative prescription that is totally algebraic. This new proposal is based on an elliptic algebraic curve embedded in a mathbb{C}{P}^2 space. We show that for the simplest integrand, namely the n - gon, our proposal indeed reproduces the expected result. By using the recently formulated Λ-algorithm, we found a novel recurrence relation expansion in terms of tree level off-shell amplitudes. Our results connect nicely with recent results on the one-loop formulation of the scattering equations. In addition, this new proposal can be easily stretched out to hyperelliptic curves in order to compute higher genus.
On nonautonomous Dirac equation
Hovhannisyan, Gro; Liu Wen
2009-12-15
We construct the fundamental solution of time dependent linear ordinary Dirac system in terms of unknown phase functions. This construction gives approximate representation of solutions which is useful for the study of asymptotic behavior. Introducing analog of Rayleigh quotient for differential equations we generalize Hartman-Wintner asymptotic integration theorems with the error estimates for applications to the Dirac system. We also introduce the adiabatic invariants for the Dirac system, which are similar to the adiabatic invariant of Lorentz's pendulum. Using a small parameter method it is shown that the change in the adiabatic invariants approaches zero with the power speed as a small parameter approaches zero. As another application we calculate the transition probabilities for the Dirac system. We show that for the special choice of electromagnetic field, the only transition of an electron to the positron with the opposite spin orientation is possible.
A low-cost digital image correlation based constitutive sensor
NASA Astrophysics Data System (ADS)
Yun, Gun-Jin; Shang, Shen; Kunchum, Shilpa; Carletta, Joan; Nam, Si-Byung
2010-03-01
In this paper, a low-cost digital image correlation-based constitutive sensor with a novel identification algorithm that is deployable and scalable in the field is proposed. The term 'constitutive sensor' is coined herein to describe a sensor that is capable of determining the target material constitutive parameters. The proposed method is different from existing identification methods in that it does not need to solve boundary value problems of the target materials using updated parameters. Since the development of the digital image correlation (DIC) technique in the 1980s, the DIC technique has been broadly evaluated and improved for measuring full-field displacements of test specimens, mainly in laboratory settings. Although its potential in damage and mechanical identification is immense, the high cost of current commercial DIC systems makes it difficult to apply the DIC technique to in-field health monitoring of structures. To realize a first ever application of DIC in the field, a prototypical low-cost sensing unit consisting of a high performance embedded microprocessor board, a low-cost web camera, and a communication module is suggested. In the proposed constitutive sensor, DIC displacement fields considered as true values are used in computing stress fields satisfying the equilibrium condition and strain fields using finite element concepts. The unknown constitutive law is initially assumed to be fully anisotropic and linear elastic. A steady state genetic algorithm is utilized to search for the material parameters by minimizing a cost function that measures energy residuals. The main features that allow the sensor to be deployable in the field are introduced, and a validation of the proposed constitutive sensor concept using synthetic data is presented.
Nonlinear flap-lag axial equations of a rotating beam
NASA Technical Reports Server (NTRS)
Kaza, K. R. V.; Kvaternik, R. G.
1977-01-01
It is possible to identify essentially four approaches by which analysts have established either the linear or nonlinear governing equations of motion for a particular problem related to the dynamics of rotating elastic bodies. The approaches include the effective applied load artifice in combination with a variational principle and the use of Newton's second law, written as D'Alembert's principle, applied to the deformed configuration. A third approach is a variational method in which nonlinear strain-displacement relations and a first-degree displacement field are used. The method introduced by Vigneron (1975) for deriving the linear flap-lag equations of a rotating beam constitutes the fourth approach. The reported investigation shows that all four approaches make use of the geometric nonlinear theory of elasticity. An alternative method for deriving the nonlinear coupled flap-lag-axial equations of motion is also discussed.
Problems of orthotropic plastic constitutive models: Non-associated flow and evolution of anisotropy
NASA Astrophysics Data System (ADS)
Pan, Haizhen
Two main topics are addressed in this thesis for anisotropic plastic behavior, e.g. textured polycrystals: (i) non-associated plastic flow and (ii) deformation-induced evolution of microstructure. We consider a class of elastic-plastic materials that possess local orthotropic symmetry which is represented in terms of second-order orientation tensors. In developing constitutive equations, significant use is made of representation theory for functions of tensors (Wang, 1969, 1970; Smith, 1969, 1970). Recent developments in multiscale modeling have unequivocally demonstrated that plastic flow in a wide range of crystalline materials is non-associative (i.e., distinct yield and flow functions) due to the effects of non-glide stresses on the motion of dislocations and slip. As a consequence, experimental observations of tension and compression asymmetries are widely approached. To describe orthotropic, non-associated behavior for polycrystals, yield and flow functions are developed based upon representation theory. Anisotropic plastic flow is commonplace for all materials possessing non-random microstructures. The second part of work focuses on the development of anisotropic elastic-plastic constitutive models to account microstructural evolution. Examples of material systems include polycrystals, whisker-reinforced composites, polymers, as well as complex viscoplastic fluids. For persistent orthotropic behavior, microstructural evolution is represented by the rotation of orthonormal vectors, which is governed by the constitutive relations for plastic spin. Representations for scalar- and tensor-valued functions of tensors are also utilized to develop phenomenological constitutive relations for plastic spin. Good agreement is demonstrated with experimental data for microstructural evolution in textured polycrystals. The effects of both non-associated flow and evolution of microstructure on strain localization are investigated. From the analyses of stress and load maxima
Constitutive response of Rene 80 under thermal mechanical loads
NASA Technical Reports Server (NTRS)
Kim, K. S.; Cook, T. S.; Mcknight, R. L.
1988-01-01
The applicability of a classical constitutive model for stress-strain analysis of a nickel base superalloy, Rene' 80, in the gas turbine thermomechanical fatigue (TMF) environment is examined. A variety of tests were conducted to generate basic material data and to investigate the material response under cyclic thermomechanical loading. Isothermal stress-strain data were acquired at a variety of strain rates over the TMF temperature range. Creep curves were examined at 2 temperature ranges, 871 to 982 C and 760 to 871 C. The results provide optimism on the ability of the classical constitutive model for high temperature applications.
Are there reliable constitutive laws for dynamic friction?
Woodhouse, Jim; Putelat, Thibaut; McKay, Andrew
2015-09-28
Structural vibration controlled by interfacial friction is widespread, ranging from friction dampers in gas turbines to the motion of violin strings. To predict, control or prevent such vibration, a constitutive description of frictional interactions is inevitably required. A variety of friction models are discussed to assess their scope and validity, in the light of constraints provided by different experimental observations. Three contrasting case studies are used to illustrate how predicted behaviour can be extremely sensitive to the choice of frictional constitutive model, and to explore possible experimental paths to discriminate between and calibrate dynamic friction models over the full parameter range needed for real applications.
Image-driven constitutive modeling of myocardial fibrosis
NASA Astrophysics Data System (ADS)
Wang, Vicky Y.; Niestrawska, Justyna A.; Wilson, Alexander J.; Sands, Gregory B.; Young, Alistair A.; LeGrice, Ian J.; Nash, Martyn P.
2016-05-01
Myocardial fibrosis is a pathological process that occurs during heart failure (HF). It involves microstructural remodeling of normal myocardial tissue, and consequent changes in both cardiac geometry and function. The role of myocardial structural remodeling in the progression of HF remains poorly understood. We propose a constitutive modeling framework, informed by high-resolution images of cardiac tissue structure, to model the mechanical response of normal and fibrotic myocardium. This image-driven constitutive modeling approach allows us to better reproduce and understand the relationship between structural and functional remodeling of ventricular myocardium during HF.
Consistency of certain constitutive relations with quantum electromagnetism
Horsley, S. A. R.
2011-12-15
Recent work by Philbin [New J. Phys. 12, 123008 (2010)] has provided a Lagrangian theory that establishes a general method for the canonical quantization of the electromagnetic field in any dispersive, lossy, linear dielectric. Working from this theory, we extend the Lagrangian description to reciprocal and nonreciprocal magnetoelectric (bianisotropic) media, showing that some versions of the constitutive relations are inconsistent with a real Lagrangian, and hence with quantization. This amounts to a restriction on the magnitude of the magnetoelectric coupling. Moreover, from the point of view of quantization, moving media are shown to be fundamentally different from stationary magnetoelectrics, despite the formal similarity in the constitutive relations.
Constitutive models for rubber networks undergoing simultaneous crosslinking and scission.
Thompson, Aidan Patrick; Curro, John G.; Rottach, Dana R.; Grest, Gary Stephen; Budzien, Joanne L.; Lo, David Chi S.
2006-01-01
Constitutive models for chemically reacting networks are formulated based on a generalization of the independent network hypothesis. These models account for the coupling between chemical reaction and strain histories, and have been tested by comparison with microscopic molecular dynamics simulations. An essential feature of these models is the introduction of stress transfer functions that describe the interdependence between crosslinks formed and broken at various strains. Efforts are underway to implement these constitutive models into the finite element code Adagio. Preliminary results are shown that illustrate the effects of changing crosslinking and scission rates and history.
A preliminary ferritic-martensitic stainless steel constitution diagram
Balmforth, M.C.; Lippold, J.C.
1998-01-01
This paper describes preliminary research to develop a constitution diagram that will more accurately predict the microstructure of ferritic and martensitic stainless steel weld deposits. A button melting technique was used to produce a wide range of compositions using mixtures of conventional ferritic and martensitic stainless steels, including types 403, 409, 410, 430, 439 and 444. These samples were prepared metallographically, and the vol-% ferrite and martensite was determined quantitatively. In addition, the hardness and ferrite number (FN) were measured. Using this data, a preliminary constitution diagram is proposed that provides a more accurate method for predicting the microstructures of arc welds in ferritic and martensitic stainless steels.
Are there reliable constitutive laws for dynamic friction?
Woodhouse, Jim; Putelat, Thibaut; McKay, Andrew
2015-09-28
Structural vibration controlled by interfacial friction is widespread, ranging from friction dampers in gas turbines to the motion of violin strings. To predict, control or prevent such vibration, a constitutive description of frictional interactions is inevitably required. A variety of friction models are discussed to assess their scope and validity, in the light of constraints provided by different experimental observations. Three contrasting case studies are used to illustrate how predicted behaviour can be extremely sensitive to the choice of frictional constitutive model, and to explore possible experimental paths to discriminate between and calibrate dynamic friction models over the full parameter range needed for real applications. PMID:26303920
Using the scalable nonlinear equations solvers package
Gropp, W.D.; McInnes, L.C.; Smith, B.F.
1995-02-01
SNES (Scalable Nonlinear Equations Solvers) is a software package for the numerical solution of large-scale systems of nonlinear equations on both uniprocessors and parallel architectures. SNES also contains a component for the solution of unconstrained minimization problems, called SUMS (Scalable Unconstrained Minimization Solvers). Newton-like methods, which are known for their efficiency and robustness, constitute the core of the package. As part of the multilevel PETSc library, SNES incorporates many features and options from other parts of PETSc. In keeping with the spirit of the PETSc library, the nonlinear solution routines are data-structure-neutral, making them flexible and easily extensible. This users guide contains a detailed description of uniprocessor usage of SNES, with some added comments regarding multiprocessor usage. At this time the parallel version is undergoing refinement and extension, as we work toward a common interface for the uniprocessor and parallel cases. Thus, forthcoming versions of the software will contain additional features, and changes to parallel interface may result at any time. The new parallel version will employ the MPI (Message Passing Interface) standard for interprocessor communication. Since most of these details will be hidden, users will need to perform only minimal message-passing programming.
Theory and identification of a constitutive model of induced anisotropy by the Mullins effect
NASA Astrophysics Data System (ADS)
Machado, G.; Chagnon, G.; Favier, D.
2014-02-01
Rubber-like materials present a stress softening phenomenon after a first loading known as the Mullins effect. Some recent experimental data on filled silicone rubber are presented in the literature, using uniaxial and biaxial tests to precondition samples thus induce some primary stress softening. A generic modeling based on the polymer network decomposition into an isotropic hyperelastic one, and a stress-softening evolutive one, is proposed taking into account the contribution of many spatial directions. A new stress softening criterion is built by means of a tensor that measures the repartition of energy in space. A general form of the stress softening function associated to a spatial direction is written by the way of two variables: one, the maximal eigenvalue of the energy tensor; the other, the energy in the considered direction. Finally, a particular form of constitutive equation is proposed. The model is fitted and compared to experimental data. The capacities of such modeling are finally discussed.
Description of tantalum deformation behavior by dislocation mechanics based constitutive relations
NASA Astrophysics Data System (ADS)
Zerilli, Frank J.; Armstrong, Ronald W.
1990-08-01
Dislocation mechanics based constitutive equation constants are determined for temperature, strain rate, work hardening, and polycrystal grain size influences on the deformation behavior of various tantalum materials. An analysis of the maximum load point strain provides a useful method of determining the work hardening constants. Different athermal stress constants and thermal activation related constants are obtained for certain groupings of the different tantalum materials. The variation are correlated with the annealing history of the materials and related to dislocation model parameters involved in the thermal activation strain rate analysis. Computed tantalum deformation results based on these constants are shown to agree with Gourdin's reported expanding ring test measurements and with the deformed shape of a Taylor cylinder impact test specimen.
A Unified Constitutive Relationship for the Time-dependent Behavior of Fast Breeder Alloys
NASA Technical Reports Server (NTRS)
Robinson, D. N.
1983-01-01
Constitutive equations based on classical concepts of creep and plasticity generally rest on the assumption that the inelastic strain can be decomposed into two distinct and additive contributions, one time dependent (creep) and the other time dependent (plastic). It is suggested that an approach is to adopt a unified representation in which creep and plasticity are characterized as occurring simultaneously and interactively and time is an essential ingredient throughout. Examples of the inherent time dependency exhibited by some fast breeder alloys at elevated temperature are rate dependency under monotonic and cyclic straining, thermal recovery and strong creep-elasticity interaction. The stron influence of the recent history of plastic straining on stress relaxation is shown.
Modeling and Algorithmic Approaches to Constitutively-Complex, Microstructured Fluids
Miller, Gregory H.; Forest, Gregory
2014-05-01
We present a new multiscale model for complex fluids based on three scales: microscopic, kinetic, and continuum. We choose the microscopic level as Kramers' bead-rod model for polymers, which we describe as a system of stochastic differential equations with an implicit constraint formulation. The associated Fokker-Planck equation is then derived, and adiabatic elimination removes the fast momentum coordinates. Approached in this way, the kinetic level reduces to a dispersive drift equation. The continuum level is modeled with a finite volume Godunov-projection algorithm. We demonstrate computation of viscoelastic stress divergence using this multiscale approach.
Entwined paths, difference equations, and the Dirac equation
Ord, G.N.; Mann, R.B.
2003-02-01
Entwined space-time paths are bound pairs of trajectories which are traversed in opposite directions with respect to macroscopic time. In this paper, we show that ensembles of entwined paths on a discrete space-time lattice are simply described by coupled difference equations which are discrete versions of the Dirac equation. There is no analytic continuation, explicit or forced, involved in this description. The entwined paths are ''self-quantizing.'' We also show that simple classical stochastic processes that generate the difference equations as ensemble averages are stable numerically and converge at a rate governed by the details of the stochastic process. This result establishes the Dirac equation in one dimension as a phenomenological equation describing an underlying classical stochastic process, in the same sense that the diffusion and telegraph equations are phenomenological descriptions of stochastic processes.