New soliton solution to the longitudinal wave equation in a magneto-electro-elastic circular rod

Directory of Open Access Journals (Sweden)

Aly R. Seadawy

2018-03-01

Full Text Available This paper examines the effectiveness of an integration scheme which called the extended trial equation method (ETEM in exactly solving a well-known nonlinear equation of partial differential equations (PDEs. In this respect, the longitudinal wave equation (LWE that arises in mathematical physics with dispersion caused by the transverse Poisson’s effect in a magneto-electro-elastic (MEE circular rod, which a series of exact traveling wave solutions for the aforementioned equation is formally extracted. Explicit new exact solutions are derived in different form such as dark solitons, bright solitons, solitary wave, periodic solitary wave, rational function, and elliptic function solutions of the longitudinal wave equation. The movements of obtained solutions are shown graphically, which helps to understand the physical phenomena of this longitudinal wave equation. Many other such types of nonlinear equations arising in non-destructive evaluation of structures made of the advanced MEE material can also be solved by this method. Keywords: Extended trial equation method, Longitudinal wave equation in a MEE circular rod, Dark solitons, Bright solitons, Solitary wave, Periodic solitary wave

determination of stresses caused by infinitely long line loads on ...

African Journals Online (AJOL)

user

2016-10-04

Oct 4, 2016 ... long line loads on semi-infinite homogeneous elastic soils. Airy's stress functions of the Cartesian coordinates system were used to express the governing equations of plane strain elasticity for a semi-infinite homogeneous soil as a biharmonic problem. The fourth order partial differential equation was then ...

Boundary crossover in semi-infinite non-equilibrium growth processes

International Nuclear Information System (INIS)

Allegra, Nicolas; Fortin, Jean-Yves; Henkel, Malte

2014-01-01

The growth of stochastic interfaces in the vicinity of a boundary and the non-trivial crossover towards the behaviour deep in the bulk are analysed. The causal interactions of the interface with the boundary lead to a roughness larger near to the boundary than deep in the bulk. This is exemplified in the semi-infinite Edwards–Wilkinson model in one dimension, from both its exact solution and numerical simulations, as well as from simulations on the semi-infinite one-dimensional Kardar–Parisi–Zhang model. The non-stationary scaling of interface heights and widths is analysed and a universal scaling form for the local height profile is proposed. (paper)

On a class of problems on interaction of stress concentrators of different types with an elastic semi-infinite plate

Science.gov (United States)

Mkhitaryan, S. M.

2018-04-01

A class of mixed boundary-value problems of mathematical theory of elasticity dealing with interaction between stress concentrators of different types (such as cracks, absolutely rigid thin inclusions, punches, and stringers) and an elastic semi-infinite plate is considered. The method of Mellin integral transformation is used to reduce solving these problems to solving singular integral equations (SIE). After the governing SIE are solved, the following characteristics of the problem are determined: tangential contact stresses under stringers, dislocation density on the crack edges, breaking stresses outside the cracks on their line of location, the stress intensity factor (SIF), crack openings, jumps of contact stresses on the edges of inclusions.

Numerical and spectral investigations of novel infinite elements

International Nuclear Information System (INIS)

Barai, P.; Harari, I.; Barbonet, P.E.

1998-01-01

Exterior problems of time-harmonic acoustics are addressed by a novel infinite element formulation, defined on a bounded computational domain. For two-dimensional configurations with circular interfaces, the infinite element results match Quell both analytical values and those obtained from. other methods like DtN. Along 1uith the numerical performance of this formulation, of considerable interest are its complex-valued eigenvalues. Hence, a spectral analysis of the present scheme is also performed here, using various infinite elements

Effect of Couple Stresses on the Stress Intensity Factors for Two Parallel Cracks in an Infinite Elastic Medium under Tension

Directory of Open Access Journals (Sweden)

Shouetsu Itou

2012-01-01

Full Text Available Stresses around two parallel cracks of equal length in an infinite elastic medium are evaluated based on the linearized couple-stress theory under uniform tension normal to the cracks. Fourier transformations are used to reduce the boundary conditions with respect to the upper crack to dual integral equations. In order to solve these equations, the differences in the displacements and in the rotation at the upper crack are expanded through a series of functions that are zero valued outside the crack. The unknown coefficients in each series are solved in order to satisfy the boundary conditions inside the crack using the Schmidt method. The stresses are expressed in terms of infinite integrals, and the stress intensity factors can be determined using the characteristics of the integrands for an infinite value of the variable of integration. Numerical calculations are carried out for selected crack configurations, and the effect of the couple stresses on the stress intensity factors is revealed.

Elastic unloading of a disk after plastic deformation by a circular heat source

International Nuclear Information System (INIS)

Gamer, U.; Mack, W.

1987-01-01

Subject of the investigation is the transient stress distribution in an elastic-plastic disk acted upon by a circular heat source. The disk serves as a mechanical model of the rotating anode of an X-ray-tube. The calculation is based on Tresca's yield criterion and the flow rule associatd to it. During heating, a plastic region spreads around the source, which is absorbed by an unloaded zone after the removal of the source. (orig.) [de

Elastic properties of spherically anisotropic piezoelectric composites

International Nuclear Information System (INIS)

En-Bo, Wei; Guo-Qing, Gu; Ying-Ming, Poon

2010-01-01

Effective elastic properties of spherically anisotropic piezoelectric composites, whose spherically anisotropic piezoelectric inclusions are embedded in an infinite non-piezoelectric matrix, are theoretically investigated. Analytical solutions for the elastic displacements and the electric potentials under a uniform external strain are derived exactly. Taking into account of the coupling effects of elasticity, permittivity and piezoelectricity, the formula is derived for estimating the effective elastic properties based on the average field theory in the dilute limit. An elastic response mechanism is revealed, in which the effective elastic properties increase as inclusion piezoelectric properties increase and inclusion dielectric properties decrease. Moreover, a piezoelectric response mechanism, of which the effective piezoelectric response vanishes due to the symmetry of spherically anisotropic composite, is also disclosed. (condensed matter: structure, thermal and mechanical properties)

Infinite families of (non)-Hermitian Hamiltonians associated with exceptional Xm Jacobi polynomials

International Nuclear Information System (INIS)

Midya, Bikashkali; Roy, Barnana

2013-01-01

Using an appropriate change of variable, the Schrödinger equation is transformed into a second-order differential equation satisfied by recently discovered Jacobi-type X m exceptional orthogonal polynomials. This facilitates the derivation of infinite families of exactly solvable Hermitian as well as non-Hermitian trigonometric Scarf potentials and a finite number of Hermitian and an infinite number of non-Hermitian PT-symmetric hyperbolic Scarf potentials. The bound state solutions of all these potentials are associated with the aforesaid exceptional orthogonal polynomials. These infinite families of potentials are shown to be extensions of the conventional trigonometric and hyperbolic Scarf potentials by the addition of some rational terms characterized by the presence of classical Jacobi polynomials. All the members of a particular family of these ‘rationally extended polynomial-dependent’ potentials have the same energy spectrum and possess translational shape-invariant symmetry. The obtained non-Hermitian trigonometric Scarf potentials are shown to be quasi-Hermitian in nature ensuring the reality of the associated energy spectra. (paper)

A numerical study of transient mass transport through a circular hole connecting two semi-infinite media

International Nuclear Information System (INIS)

DePaoli, D.W.; Scott, T.C.

1993-01-01

A numerical model of transient diffusive mass transfer through a circular hole that connects two semi-infinite media was used as a means of determining potential effects of waste container penetrations on the release of immobilized contaminants into the environment. The finite difference model as developed necessarily includes treatment of mass transport in both the waste and surrounding medium and allows calculation of release rates for cases with and without preferential adsorption and differing diffusivities of the two media. The dimensionless contaminant release rate was found to vary over several orders of magnitude depending on the product of the ratio of the distribution coefficient and the media diffusivities only. As would be intuitively expected, partitioning favoring the surrounding medium and higher relative waste medium diffusivity cause higher transport rates. There was definitely no unexpected enhancement in the release rate in the case of perforations over that of an uncontained waste form

New soliton solution to the longitudinal wave equation in a magneto-electro-elastic circular rod

Science.gov (United States)

Seadawy, Aly R.; Manafian, Jalil

2018-03-01

This paper examines the effectiveness of an integration scheme which called the extended trial equation method (ETEM) in exactly solving a well-known nonlinear equation of partial differential equations (PDEs). In this respect, the longitudinal wave equation (LWE) that arises in mathematical physics with dispersion caused by the transverse Poisson's effect in a magneto-electro-elastic (MEE) circular rod, which a series of exact traveling wave solutions for the aforementioned equation is formally extracted. Explicit new exact solutions are derived in different form such as dark solitons, bright solitons, solitary wave, periodic solitary wave, rational function, and elliptic function solutions of the longitudinal wave equation. The movements of obtained solutions are shown graphically, which helps to understand the physical phenomena of this longitudinal wave equation. Many other such types of nonlinear equations arising in non-destructive evaluation of structures made of the advanced MEE material can also be solved by this method.

A circular aperture array for ultrasonic tomography and quantitative NDE

Energy Technology Data Exchange (ETDEWEB)

Nielsen, S A

1998-08-01

The main topics of this thesis are ultrasonic tomography and ultrasonic determination of elastic stiffness constants. Both issues are based on a synthetic array with transducer elements distributed uniformly along a circular aperture, i.e., a circular aperture array. The issues are treated both theoretically and experimentally by broadband pulse techniques. Ultrasonic tomography, UCT, from a circular aperture is a relatively new imaging technique in Non-destructive Evaluation (NDE) to acquire cross sectional images in bulk materials. A filtered back-projection algorithm is used to reconstruct images in four different experiments and results of attenuation, velocity and reflection tomograms in Plexiglas of AlSi-alloy cylinders are presented. Two kinds of ultrasonic tomography are introduced: bistatic and monostatic imaging. Both techniques are verified experimentally by Plexiglas cylinders. Different reconstruction artifacts are discussed and theoretical resolution constraints are discussed for various configurations of the circular aperture array. The monostatic technique is used in volumetric imaging. In the experimental verification artificial and real discontinuities in a cylindrical AlSi-alloy are compared with similar discontinuities in a Plexiglas specimen. Finally, some limitations to UCT are discussed. The circular aperture array is used to determine five independent elastic stiffness constants of a unidirectional glass/PET (Poly Ethylene Teraphtalate) laminate. Energy flux propagation and attenuation of ultrasonic waves are considered and velocity surfaces are calculated for different planes of interest. Relations between elastic stiffness constants and engineering constants (i.e., Young`s moduli, shear moduli and Poisson`s ratios) are discussed for an orthotropic composite. Six micromechanical theories are reviewed, and expressions predicting the elastic engineering constants are evaluated. The micromechanical predicted elastic stiffness constants for the

Infinite stochastic acceleration of charged particles from non-relativistic initial energies

International Nuclear Information System (INIS)

Buts, V.A.; Manujlenko, O.V.; Turkin, Yu.A.

1997-01-01

Stochastic charged particle acceleration by electro-magnetic field due to overlapping of non-linear cyclotron resonances is considered. It was shown that non-relativistic charged particles are involved in infinitive stochastic acceleration regime. This effect can be used for stochastic acceleration or for plasma heating by regular electro-magnetic fields

Quasi-integrable non-linear Schrödinger models, infinite towers of exactly conserved charges and bright solitons

Science.gov (United States)

Blas, H.; do Bonfim, A. C. R.; Vilela, A. M.

2017-05-01

Deformations of the focusing non-linear Schrödinger model (NLS) are considered in the context of the quasi-integrability concept. We strengthen the results of JHEP 09 (2012) 103 10.1007/JHEP06(2015)177" TargetType="URL"/> for bright soliton collisions. We addressed the focusing NLS as a complement to the one in JHEP 03 (2016) 005 10.1007/JHEP06(2015)177" TargetType="URL"/> , in which the modified defocusing NLS models with dark solitons were shown to exhibit an infinite tower of exactly conserved charges. We show, by means of analytical and numerical methods, that for certain two-bright-soliton solutions, in which the modulus and phase of the complex modified NLS field exhibit even parities under a space-reflection symmetry, the first four and the sequence of even order charges are exactly conserved during the scattering process of the solitons. We perform extensive numerical simulations and consider the bright solitons with deformed potential V=2η /2+\\upepsilon{({|ψ |}^2)}^{2+\\upepsilon},\\upepsilon \\in \\mathbb{R},η <0 . However, for two-soliton field components without definite parity we also show numerically the vanishing of the first non-trivial anomaly and the exact conservation of the relevant charge. So, the parity symmetry seems to be a sufficient but not a necessary condition for the existence of the infinite tower of conserved charges. The model supports elastic scattering of solitons for a wide range of values of the amplitudes and velocities and the set { η, ɛ}. Since the NLS equation is ubiquitous, our results may find potential applications in several areas of non-linear science.

Energy in elastic fiber embedded in elastic matrix containing incident SH wave

Science.gov (United States)

Williams, James H., Jr.; Nagem, Raymond J.

1989-01-01

A single elastic fiber embedded in an infinite elastic matrix is considered. An incident plane SH wave is assumed in the infinite matrix, and an expression is derived for the total energy in the fiber due to the incident SH wave. A nondimensional form of the fiber energy is plotted as a function of the nondimensional wavenumber of the SH wave. It is shown that the fiber energy attains maximum values at specific values of the wavenumber of the incident wave. The results obtained here are interpreted in the context of phenomena observed in acousto-ultrasonic experiments on fiber reinforced composite materials.

Free vibration analysis of elastic structures submerged in an infinite or semi-infinite fluid domain by means of a coupled FE-BE solver

Science.gov (United States)

Zheng, Chang-Jun; Bi, Chuan-Xing; Zhang, Chuanzeng; Gao, Hai-Feng; Chen, Hai-Bo

2018-04-01

The vibration behavior of thin elastic structures can be noticeably influenced by the surrounding water, which represents a kind of heavy fluid. Since the feedback of the acoustic pressure onto the structure cannot be neglected in this case, a strong coupled scheme between the structural and fluid domains is usually required. In this work, a coupled finite element and boundary element (FE-BE) solver is developed for the free vibration analysis of structures submerged in an infinite fluid domain or a semi-infinite fluid domain with a free water surface. The structure is modeled by the finite element method (FEM). The compressibility of the fluid is taken into account, and hence the Helmholtz equation serves as the governing equation of the fluid domain. The boundary element method (BEM) is employed to model the fluid domain, and a boundary integral formulation with a half-space fundamental solution is used to satisfy the Dirichlet boundary condition on the free water surface exactly. The resulting nonlinear eigenvalue problem (NEVP) is converted into a small linear one by using a contour integral method. Adequate modifications are suggested to improve the efficiency of the contour integral method and avoid missing the eigenfrequencies of interest. The Burton-Miller method is used to filter out the fictitious eigenfrequencies of the boundary integral formulations. Numerical examples are given to demonstrate the accuracy and applicability of the developed eigensolver, and also show that the fluid-loading effect strongly depends on both the water depth and the mode shapes.

Conformally-flat, non-singular static metric in infinite derivative gravity

Science.gov (United States)

Buoninfante, Luca; Koshelev, Alexey S.; Lambiase, Gaetano; Marto, João; Mazumdar, Anupam

2018-06-01

In Einstein's theory of general relativity the vacuum solution yields a blackhole with a curvature singularity, where there exists a point-like source with a Dirac delta distribution which is introduced as a boundary condition in the static case. It has been known for a while that ghost-free infinite derivative theory of gravity can ameliorate such a singularity at least at the level of linear perturbation around the Minkowski background. In this paper, we will show that the Schwarzschild metric does not satisfy the boundary condition at the origin within infinite derivative theory of gravity, since a Dirac delta source is smeared out by non-local gravitational interaction. We will also show that the spacetime metric becomes conformally-flat and singularity-free within the non-local region, which can be also made devoid of an event horizon. Furthermore, the scale of non-locality ought to be as large as that of the Schwarzschild radius, in such a way that the gravitational potential in any metric has to be always bounded by one, implying that gravity remains weak from the infrared all the way up to the ultraviolet regime, in concurrence with the results obtained in [arXiv:1707.00273]. The singular Schwarzschild blackhole can now be potentially replaced by a non-singular compact object, whose core is governed by the mass and the effective scale of non-locality.

Performance limits of ion extraction systems with non-circular apertures

Energy Technology Data Exchange (ETDEWEB)

Shagayda, A., E-mail: shagayda@gmail.com; Madeev, S. [Keldysh Research Centre, Onezhskaya, 8, 125438 Moscow (Russian Federation)

2016-04-15

A three-dimensional computer simulation is used to determine the perveance limitations of ion extraction systems with non-circular apertures. The objective of the study is to analyze the possibilities to improve mechanical strength of the ion optics made of carbon-carbon composite materials. Non-circular grid apertures are better suited to the physical structure of carbon-carbon composite materials, than conventionally used circular holes in a hexagonal pattern, because they allow a fewer number of cut fibers. However, the slit-type accelerating systems, usually regarded as the main alternative to the conventional ion optics, have an intolerably narrow range of operating perveance values at which there is no direct ion impingement on the acceleration grid. This paper presents results of comparative analysis of a number of different ion optical systems with non-circular apertures and conventional ion optical systems with circular apertures. It has been revealed that a relatively wide perveance range without direct ion impingement may be obtained with apertures shaped as a square with rounded corners. Numerical simulations show that this geometry may have equivalent perveance range as the traditional geometry with circular apertures while being more mechanically robust. In addition, such important characteristics, as the effective transparency for both the ions and the neutral atoms, the height of the potential barrier reflecting the downstream plasma electrons and the angular divergence of the beamlet also can be very close to these parameters for the optics with circular apertures.

Performance limits of ion extraction systems with non-circular apertures.

Science.gov (United States)

Shagayda, A; Madeev, S

2016-04-01

A three-dimensional computer simulation is used to determine the perveance limitations of ion extraction systems with non-circular apertures. The objective of the study is to analyze the possibilities to improve mechanical strength of the ion optics made of carbon-carbon composite materials. Non-circular grid apertures are better suited to the physical structure of carbon-carbon composite materials, than conventionally used circular holes in a hexagonal pattern, because they allow a fewer number of cut fibers. However, the slit-type accelerating systems, usually regarded as the main alternative to the conventional ion optics, have an intolerably narrow range of operating perveance values at which there is no direct ion impingement on the acceleration grid. This paper presents results of comparative analysis of a number of different ion optical systems with non-circular apertures and conventional ion optical systems with circular apertures. It has been revealed that a relatively wide perveance range without direct ion impingement may be obtained with apertures shaped as a square with rounded corners. Numerical simulations show that this geometry may have equivalent perveance range as the traditional geometry with circular apertures while being more mechanically robust. In addition, such important characteristics, as the effective transparency for both the ions and the neutral atoms, the height of the potential barrier reflecting the downstream plasma electrons and the angular divergence of the beamlet also can be very close to these parameters for the optics with circular apertures.

Performance limits of ion extraction systems with non-circular apertures

Science.gov (United States)

Shagayda, A.; Madeev, S.

2016-04-01

A three-dimensional computer simulation is used to determine the perveance limitations of ion extraction systems with non-circular apertures. The objective of the study is to analyze the possibilities to improve mechanical strength of the ion optics made of carbon-carbon composite materials. Non-circular grid apertures are better suited to the physical structure of carbon-carbon composite materials, than conventionally used circular holes in a hexagonal pattern, because they allow a fewer number of cut fibers. However, the slit-type accelerating systems, usually regarded as the main alternative to the conventional ion optics, have an intolerably narrow range of operating perveance values at which there is no direct ion impingement on the acceleration grid. This paper presents results of comparative analysis of a number of different ion optical systems with non-circular apertures and conventional ion optical systems with circular apertures. It has been revealed that a relatively wide perveance range without direct ion impingement may be obtained with apertures shaped as a square with rounded corners. Numerical simulations show that this geometry may have equivalent perveance range as the traditional geometry with circular apertures while being more mechanically robust. In addition, such important characteristics, as the effective transparency for both the ions and the neutral atoms, the height of the potential barrier reflecting the downstream plasma electrons and the angular divergence of the beamlet also can be very close to these parameters for the optics with circular apertures.

Performance limits of ion extraction systems with non-circular apertures

International Nuclear Information System (INIS)

Shagayda, A.; Madeev, S.

2016-01-01

A three-dimensional computer simulation is used to determine the perveance limitations of ion extraction systems with non-circular apertures. The objective of the study is to analyze the possibilities to improve mechanical strength of the ion optics made of carbon-carbon composite materials. Non-circular grid apertures are better suited to the physical structure of carbon-carbon composite materials, than conventionally used circular holes in a hexagonal pattern, because they allow a fewer number of cut fibers. However, the slit-type accelerating systems, usually regarded as the main alternative to the conventional ion optics, have an intolerably narrow range of operating perveance values at which there is no direct ion impingement on the acceleration grid. This paper presents results of comparative analysis of a number of different ion optical systems with non-circular apertures and conventional ion optical systems with circular apertures. It has been revealed that a relatively wide perveance range without direct ion impingement may be obtained with apertures shaped as a square with rounded corners. Numerical simulations show that this geometry may have equivalent perveance range as the traditional geometry with circular apertures while being more mechanically robust. In addition, such important characteristics, as the effective transparency for both the ions and the neutral atoms, the height of the potential barrier reflecting the downstream plasma electrons and the angular divergence of the beamlet also can be very close to these parameters for the optics with circular apertures.

Non-linear theory of elasticity and optimal design

CERN Document Server

Ratner, LW

2003-01-01

In order to select an optimal structure among possible similar structures, one needs to compare the elastic behavior of the structures. A new criterion that describes elastic behavior is the rate of change of deformation. Using this criterion, the safe dimensions of a structure that are required by the stress distributed in a structure can be calculated. The new non-linear theory of elasticity allows one to determine the actual individual limit of elasticity/failure of a structure using a simple non-destructive method of measurement of deformation on the model of a structure while presently it

THE STRESS-STRAIN STATE OF AN INFINITELY LONG ELASTIC ARRAYS OF DIFFERENT WIDTHS AND LIMITED THICKNESS ON THE HARD GROUND WHEN THEY HAVE FLAT DEFORMATION

Directory of Open Access Journals (Sweden)

I. K. Badalakha

2009-12-01

Full Text Available The article presents the results of solving several problems of a flat deformation of elastic infinitely long massifs of different width and limited thickness. Various cases of conditions at the massif/base contact. The relationships between stressed and strained states previously suggested by the author, which differ from the generalized Hooke’s law, are used in the solutions.

Limit moments for non circular cross-section (elliptical) pipe bends

International Nuclear Information System (INIS)

Spence, J.

1977-01-01

A number of experiment studies have been reported or are underway which investigate limit moments applied to pipe bends. Some theoretical work is also available. However, most of the work has been confined to nominally circular cross-section bends and little account has been taken of the practical problem of manufacturing tolerances. Many methods of manufacture result in bends which are not circular in cross-section but have an oval or elliptical shape. The present paper extends previous analyses on circular bends to cater for initially elliptical cross-sections. The loading is primarily in plane bending but out of plane is also considered and several independent methods are presented. No previous information is known to the authors. Upper and lower bound limit moments are derived first of all from existing linear elastic analyses and secondly upper bound moments are derived via a plastic analogy from existing stationary creep results. It is also shown that the creep information on design factors for bends can be used to obtain a reasonable estimate of the complete moment/strain behaviour of a bend or indeed a system. (Auth.)

A new type of surface acoustic waves in solids due to nonlinear elasticity

International Nuclear Information System (INIS)

Mozhaev, V.G.

1988-12-01

It is shown that in nonlinear elastic semi-infinite medium possessing a property of self focusing of shear waves, besides bulk non-linear shear waves, new surface acoustic waves exist, localization of which near the boundary is entirely due to nonlinear effects. (author). 8 refs

Collusion and the elasticity of demand

OpenAIRE

David Collie

2004-01-01

The analysis of collusion in infinitely repeated Cournot oligopoly games has generally assumed that demand is linear, but this note uses constant-elasticity demand functions to investigate how the elasticity of demand affects the sustainability of collusion.

Elastic wave diffraction by infinite wedges

Energy Technology Data Exchange (ETDEWEB)

Fradkin, Larissa; Zernov, Victor [Sound Mathematics Ltd., Cambridge CB4 2AS (United Kingdom); Gautesen, Arthur [Mathematics Department, Iowa State University and Ames Laboratory (United States); Darmon, Michel, E-mail: l.fradkin@soundmathematics.com [CEA-LIST, CEA-Saclay, 91191 Gif-sur-Yvette (France)

2011-01-01

We compare two recently developed semi-analytical approaches to the classical problem of diffraction by an elastic two dimensional wedge, one based on the reciprocity principle and Fourier Transform and another, on the representations of the elastodynamic potentials in the form of Sommerfeld Integrals. At present, in their common region of validity, the approaches are complementary, one working better than the other at some isolated angles of incidence.

Vibration of an Elastic Circular Plate on an Elastic Half Space

DEFF Research Database (Denmark)

Krenk, Steen; Schmidt, H.

1981-01-01

The axisymmetric problem of a vibrating elastic plate on an elastic half space is solved by a direct method, in which the contact stresses and the normal displacements of the plate are taken as the unknown functions. First, the influence functions that give the displacements in terms...

On infinitely divisible semimartingales

DEFF Research Database (Denmark)

Basse-O'Connor, Andreas; Rosiński, Jan

2015-01-01

to non Gaussian infinitely divisible processes. First we show that the class of infinitely divisible semimartingales is so large that the natural analog of Stricker's theorem fails to hold. Then, as the main result, we prove that an infinitely divisible semimartingale relative to the filtration generated...... by a random measure admits a unique decomposition into an independent increment process and an infinitely divisible process of finite variation. Consequently, the natural analog of Stricker's theorem holds for all strictly representable processes (as defined in this paper). Since Gaussian processes...... are strictly representable due to Hida's multiplicity theorem, the classical Stricker's theorem follows from our result. Another consequence is that the question when an infinitely divisible process is a semimartingale can often be reduced to a path property, when a certain associated infinitely divisible...

A new derivation of the conformally flat stationary cyclic non-circular spacetimes

International Nuclear Information System (INIS)

Ayon-Beato, Eloy; Campuzano, Cuauhtemoc; GarcIa, Alberto

2007-01-01

We present an alternative way to derive the conformally flat stationary cyclic non-circular spacetimes. We show that there is no room for stationary axisymmetric non-circular axisymmetric spacetimes. We reproduce the well know results for this sort of spacetimes recently reported in [1

A new derivation of the conformally flat stationary cyclic non-circular spacetimes

Energy Technology Data Exchange (ETDEWEB)

Ayon-Beato, Eloy [Departamento de Fisica, Facultad de Fisica e Inteligencia Artificial, Universidad Veracruzana, 91000 Xalapa, Veracruz (Mexico); Campuzano, Cuauhtemoc [Departamento de Fisica, Facultad de Fisica e Inteligencia Artificial, Universidad Veracruzana, 91000 Xalapa, Veracruz (Mexico); GarcIa, Alberto [Department of Physics, University of California, Davis, CA 95616 (United States)

2007-11-15

We present an alternative way to derive the conformally flat stationary cyclic non-circular spacetimes. We show that there is no room for stationary axisymmetric non-circular axisymmetric spacetimes. We reproduce the well know results for this sort of spacetimes recently reported in [1].

Deformations of a pre-stretched and lubricated finite elastic membrane driven by non-uniform external forcing

Science.gov (United States)

Boyko, Evgeniy; Gat, Amir; Bercovici, Moran

2017-11-01

We study viscous-elastic dynamics of a fluid confined between a rigid plate and a finite pre-stretched circular elastic membrane, pinned at its boundaries. The membrane is subjected to forces acting either directly on the membrane or through a pressure distribution in the fluid. Under the assumptions of strong pre-stretching and small deformations of the elastic sheet, and by applying the lubrication approximation for the flow, we derive the Green's function for the resulting linearized 4th order diffusion equation governing the deformation field in cylindrical coordinates. In addition, defining an asymptotic expansion with the ratio of the induced to prescribed tension serving as the small parameter, we reduce the coupled Reynolds and non-linear von-Karman equations to a set of three one-way coupled linear equations. The solutions to these equations provide insight onto the effects of induced tension, and enable simplified prediction of the correction for the deformation field. Funded by the European Research Council (ERC) under the European Union'sHorizon 2020 Research and Innovation Programme, Grant Agreement No. 678734 (MetamorphChip). E.B. is supported by the Adams Fellowship Program.

Surface effects on static bending of nanowires based on non-local elasticity theory

Directory of Open Access Journals (Sweden)

Quan Wu

2015-10-01

Full Text Available The surface elasticity and non-local elasticity effects on the elastic behavior of statically bent nanowires are investigated in the present investigation. Explicit solutions are presented to evaluate the surface stress and non-local elasticity effects with various boundary conditions. Compared with the classical Euler beam, a nanowire with surface stress and/or non-local elasticity can be either stiffer or less stiff, depending on the boundary conditions. The concept of surface non-local elasticity was proposed and its physical interpretation discussed to explain the combined effect of surface elasticity and non-local elasticity. The effect of the nanowire size on its elastic bending behavior was investigated. The results obtained herein are helpful to characterize mechanical properties of nanowires and aid nanowire-based devices design.

Infinite-mode squeezed coherent states and non-equilibrium statistical mechanics (phase-space-picture approach)

International Nuclear Information System (INIS)

Yeh, L.

1992-01-01

The phase-space-picture approach to quantum non-equilibrium statistical mechanics via the characteristic function of infinite- mode squeezed coherent states is introduced. We use quantum Brownian motion as an example to show how this approach provides an interesting geometrical interpretation of quantum non-equilibrium phenomena

Infinite sets of conservation laws for linear and non-linear field equations

International Nuclear Information System (INIS)

Niederle, J.

1984-01-01

The work was motivated by a desire to understand group theoretically the existence of an infinite set of conservation laws for non-interacting fields and to carry over these conservation laws to the case of interacting fields. The relation between an infinite set of conservation laws of a linear field equation and the enveloping algebra of its space-time symmetry group was established. It is shown that in the case of the Korteweg-de Vries (KdV) equation to each symmetry of the corresponding linear equation delta sub(o)uxxx=u sub() determined by an element of the enveloping algebra of the space translation algebra, there corresponds a symmetry of the full KdV equation

Vibration analysis of orthotropic circular and elliptical nano-plates embedded in elastic medium based on nonlocal Mindlin plate theory and using Galerkin method

International Nuclear Information System (INIS)

Anjomshoa, Amin; Tahani, Masoud

2016-01-01

In the present study a continuum model based on the nonlocal elasticity theory is developed for free vibration analysis of embedded ortho tropic thick circular and elliptical nano-plates rested on an elastic foundation. The elastic foundation is considered to behave like a Pasternak type of foundations. Governing equations for vibrating nano-plate are derived according to the Mindlin plate theory in which the effects of shear deformations of nano-plate are also included. The Galerkin method is then employed to obtain the size dependent natural frequencies of nano-plate. The solution procedure considers the entire nano-plate as a single super-continuum element. Effect of nonlocal parameter, lengths of nano-plate, aspect ratio, mode number, material properties, thickness and foundation on circular frequencies are investigated. It is seen that the nonlocal frequencies of the nano-plate are smaller in comparison to those from the classical theory and this is more pronounced for small lengths and higher vibration modes. It is also found that as the aspect ratio increases or the nanoplate becomes more elliptical, the small scale effect on natural frequencies increases. Further, it is observed that the elastic foundation decreases the influence of nonlocal parameter on the results. Since the effect of shear deformations plays an important role in vibration analysis and design of nano-plates, by predicting smaller values for fundamental frequencies, the study of these nano-structures using thick plate theories such as Mindlin plate theory is essential.

On generator systems for non-torsion Abelian groups of infinite free rank

International Nuclear Information System (INIS)

Lebedenko, V.M.

1977-01-01

The paper is further advance in solution of the Dlab problem related to the systems of generators of Abelian groups. Some existence criteria for hereditarily strongly reducible systems of generators of Abelian groups are presented. On this basis the distribution of non-torsion groups of infinite free rank on Dlab's classes is obtained

Classical transport in a non-circular z-pinch

International Nuclear Information System (INIS)

Eriksson, G.

1987-05-01

A method is devised, in which particle and heat fluxes are found by solving the heat balance equation self-consistently for specified profiles. The procedure is applied to an equilibrium which corresponds to a non-circular z-pinch. (author)

Beamforming with a circular array of microphones mounted on a rigid sphere (L)

DEFF Research Database (Denmark)

Tiana Roig, Elisabet; Jacobsen, Finn; Fernandez Grande, Efren

2011-01-01

Beamforming with uniform circular microphone arrays can be used for localizing sound sources over 360. Typically, the array microphones are suspended in free space or they are mounted on a solid cylinder. However, the cylinder is often considered to be infinitely long because the scattering problem...... has no exact solution for a finite cylinder. Alternatively one can use a solid sphere. This investigation compares the performance of a circular array mounded on a rigid sphere with that of such an array in free space and mounted on an infinite cylinder, using computer simulations. The examined...

Non-Conventional Thermodynamics and Models of Gradient Elasticity

Directory of Open Access Journals (Sweden)

Hans-Dieter Alber

2018-03-01

Full Text Available We consider material bodies exhibiting a response function for free energy, which depends on both the strain and its gradient. Toupin–Mindlin’s gradient elasticity is characterized by Cauchy stress tensors, which are given by space-like Euler–Lagrange derivative of the free energy with respect to the strain. The present paper aims at developing a first version of gradient elasticity of non-Toupin–Mindlin’s type, i.e., a theory employing Cauchy stress tensors, which are not necessarily expressed as Euler–Lagrange derivatives. This is accomplished in the framework of non-conventional thermodynamics. A one-dimensional boundary value problem is solved in detail in order to illustrate the differences of the present theory with Toupin–Mindlin’s gradient elasticity theory.

Mathematical Modeling of Torsional Surface Wave Propagation in a Non-Homogeneous Transverse Isotropic Elastic Solid Semi-Infinite Medium Under a Layer

Science.gov (United States)

Sethi, M.; Sharma, A.; Vasishth, A.

2017-05-01

The present paper deals with the mathematical modeling of the propagation of torsional surface waves in a non-homogeneous transverse isotropic elastic half-space under a rigid layer. Both rigidities and density of the half-space are assumed to vary inversely linearly with depth. Separation of variable method has been used to get the analytical solutions for the dispersion equation of the torsional surface waves. Also, the effects of nonhomogeneities on the phase velocity of torsional surface waves have been shown graphically. Also, dispersion equations have been derived for some particular cases, which are in complete agreement with some classical results.

Elasticity of fractal materials using the continuum model with non-integer dimensional space

Science.gov (United States)

Tarasov, Vasily E.

2015-01-01

Using a generalization of vector calculus for space with non-integer dimension, we consider elastic properties of fractal materials. Fractal materials are described by continuum models with non-integer dimensional space. A generalization of elasticity equations for non-integer dimensional space, and its solutions for the equilibrium case of fractal materials are suggested. Elasticity problems for fractal hollow ball and cylindrical fractal elastic pipe with inside and outside pressures, for rotating cylindrical fractal pipe, for gradient elasticity and thermoelasticity of fractal materials are solved.

Estimating non-circular motions in barred galaxies using numerical N-body simulations

Science.gov (United States)

Randriamampandry, T. H.; Combes, F.; Carignan, C.; Deg, N.

2015-12-01

The observed velocities of the gas in barred galaxies are a combination of the azimuthally averaged circular velocity and non-circular motions, primarily caused by gas streaming along the bar. These non-circular flows must be accounted for before the observed velocities can be used in mass modelling. In this work, we examine the performance of the tilted-ring method and the DISKFIT algorithm for transforming velocity maps of barred spiral galaxies into rotation curves (RCs) using simulated data. We find that the tilted-ring method, which does not account for streaming motions, under-/overestimates the circular motions when the bar is parallel/perpendicular to the projected major axis. DISKFIT, which does include streaming motions, is limited to orientations where the bar is not aligned with either the major or minor axis of the image. Therefore, we propose a method of correcting RCs based on numerical simulations of galaxies. We correct the RC derived from the tilted-ring method based on a numerical simulation of a galaxy with similar properties and projections as the observed galaxy. Using observations of NGC 3319, which has a bar aligned with the major axis, as a test case, we show that the inferred mass models from the uncorrected and corrected RCs are significantly different. These results show the importance of correcting for the non-circular motions and demonstrate that new methods of accounting for these motions are necessary as current methods fail for specific bar alignments.

The belt pinch - a high-β tokamak with non-circular cross-section

International Nuclear Information System (INIS)

Gruber, O.; Peiry, J.M.; Wilhelm, R.

1975-10-01

The stability behaviour of non-circular plasma cross-sections is discussed on the basis of present known theory. Then the technical arrangement and the preionization of the Belt Pinch is described. The following section deals with the establishment of the non-circular equilibrium and summarizes the essential plasma paramters and the used diagnostic methods. The stability properties of the Belt Pinch, lead to a critical q-value. Finnaly, supporting experiments for the future Belt Pinch programm are presented. (orig./GG) [de

Non-Asymptotic Confidence Sets for Circular Means

Directory of Open Access Journals (Sweden)

Thomas Hotz

2016-10-01

Full Text Available The mean of data on the unit circle is defined as the minimizer of the average squared Euclidean distance to the data. Based on Hoeffding’s mass concentration inequalities, non-asymptotic confidence sets for circular means are constructed which are universal in the sense that they require no distributional assumptions. These are then compared with asymptotic confidence sets in simulations and for a real data set.

Elasticity problems in domains with nonsmooth boundaries

International Nuclear Information System (INIS)

Esparza, David

2001-01-01

In the present work we study the behaviour of elastic stress fields in domains with non-regular boundaries. We consider three-dimensional problems in elastic media with thin conical defects (inclusions or cavities) and analyse the stress singularity at their vertices. To construct asymptotic expansions for the stress and displacement fields in terms of a small parameter ε related to the 'thickness' of the defect, we employ a technique based on the work by Kondrat'ev, Maz'ya, Nazarov and Plamenevskii. We first study the stress distribution in an elastic body with a thin conical notch. We derive an asymptotic representation for the stress singularity exponent by reducing the original problem to a spectral problem for a 9x9 matrix. The elements of this matrix are found to depend upon the geometry of the cross-section of the notch and the elastic properties of the medium. We specify the sets of eigenvalues and the corresponding eigenvectors for a circular, elliptical, 'triangular' and 'square' cross-section, and show that the strongest singularity is associated with the 'triangular' cross-section, and is generated by a non-axisymmetric load. We then analyse the stress distribution near a thin conical inclusion which is allowed to slide freely along its axis. We derive the representation for the stress singularity exponent for the case of a circular conical inclusion whose elastic properties differ from those of the medium. In the last chapter we study the stress distribution in the vicinity of a thin 'coated' conical inclusion. We show that a soft thin coating (perfectly bonded to the inclusion and the surrounding material) can be replaced by a so-called linear interface at which the normal displacement is discontinuous, and the stresses are proportional to the 'jump' in the normal displacement across the coating. We analyse the effect of the properties of the coating on the stress singularity exponent and compare the results with those for a perfectly bonded

Characteristics of a Circular Logic and Its Treatment

International Nuclear Information System (INIS)

Lim, Ho-Gon; Han, Sang-Hoon; Yang, Joon Eon

2007-01-01

A circular logic or a logical loop is defined as the infinite circulation of supporting relations due to their mutual dependencies among the systems in the Fault Tree Analysis (FTA). While many methods to break the circular logic have been developed and used in the fault tree quantification codes, the general solution for a circular logic and its breaking methods are not generally known as yet. This paper presents an analytic solution for circular logics in which the systems are linearly interrelated with each other. Then, a general treatment of circular logics is discussed. To formulate the analytic solution, the relations among systems in the fault tree structure are described by the Boolean equations. The solution is, then, obtained from the successive substitutions of the Boolean equations, which is equivalent to the attaching processes of interrelated system's fault tree to a given fault tree. The solution for three interrelated systems and their independent fault tree structures are given as an example

Frequency tuning, nonlinearities and mode coupling in circular mechanical graphene resonators

International Nuclear Information System (INIS)

Eriksson, A M; Midtvedt, D; Croy, A; Isacsson, A

2013-01-01

We study circular nanomechanical graphene resonators by means of continuum elasticity theory, treating them as membranes. We derive dynamic equations for the flexural mode amplitudes. Due to the geometrical nonlinearity the mode dynamics can be modeled by coupled Duffing equations. By solving the Airy stress problem we obtain analytic expressions for the eigenfrequencies and nonlinear coefficients as functions of the radius, suspension height, initial tension, back-gate voltage and elastic constants, which we compare with finite element simulations. Using perturbation theory, we show that it is necessary to include the effects of the non-uniform stress distribution for finite deflections. This correctly reproduces the spectrum and frequency tuning of the resonator, including frequency crossings. (paper)

Direct Position Determination of Multiple Non-Circular Sources with a Moving Coprime Array

Directory of Open Access Journals (Sweden)

Yankui Zhang

2018-05-01

Full Text Available Direct position determination (DPD is currently a hot topic in wireless localization research as it is more accurate than traditional two-step positioning. However, current DPD algorithms are all based on uniform arrays, which have an insufficient degree of freedom and limited estimation accuracy. To improve the DPD accuracy, this paper introduces a coprime array to the position model of multiple non-circular sources with a moving array. To maximize the advantages of this coprime array, we reconstruct the covariance matrix by vectorization, apply a spatial smoothing technique, and converge the subspace data from each measuring position to establish the cost function. Finally, we obtain the position coordinates of the multiple non-circular sources. The complexity of the proposed method is computed and compared with that of other methods, and the Cramer–Rao lower bound of DPD for multiple sources with a moving coprime array, is derived. Theoretical analysis and simulation results show that the proposed algorithm is not only applicable to circular sources, but can also improve the positioning accuracy of non-circular sources. Compared with existing two-step positioning algorithms and DPD algorithms based on uniform linear arrays, the proposed technique offers a significant improvement in positioning accuracy with a slight increase in complexity.

Direct Position Determination of Multiple Non-Circular Sources with a Moving Coprime Array.

Science.gov (United States)

Zhang, Yankui; Ba, Bin; Wang, Daming; Geng, Wei; Xu, Haiyun

2018-05-08

Direct position determination (DPD) is currently a hot topic in wireless localization research as it is more accurate than traditional two-step positioning. However, current DPD algorithms are all based on uniform arrays, which have an insufficient degree of freedom and limited estimation accuracy. To improve the DPD accuracy, this paper introduces a coprime array to the position model of multiple non-circular sources with a moving array. To maximize the advantages of this coprime array, we reconstruct the covariance matrix by vectorization, apply a spatial smoothing technique, and converge the subspace data from each measuring position to establish the cost function. Finally, we obtain the position coordinates of the multiple non-circular sources. The complexity of the proposed method is computed and compared with that of other methods, and the Cramer⁻Rao lower bound of DPD for multiple sources with a moving coprime array, is derived. Theoretical analysis and simulation results show that the proposed algorithm is not only applicable to circular sources, but can also improve the positioning accuracy of non-circular sources. Compared with existing two-step positioning algorithms and DPD algorithms based on uniform linear arrays, the proposed technique offers a significant improvement in positioning accuracy with a slight increase in complexity.

One-Dimensional Mass-Spring Chains Supporting Elastic Waves with Non-Conventional Topology

Directory of Open Access Journals (Sweden)

2016-04-01

Full Text Available There are two classes of phononic structures that can support elastic waves with non-conventional topology, namely intrinsic and extrinsic systems. The non-conventional topology of elastic wave results from breaking time reversal symmetry (T-symmetry of wave propagation. In extrinsic systems, energy is injected into the phononic structure to break T-symmetry. In intrinsic systems symmetry is broken through the medium microstructure that may lead to internal resonances. Mass-spring composite structures are introduced as metaphors for more complex phononic crystals with non-conventional topology. The elastic wave equation of motion of an intrinsic phononic structure composed of two coupled one-dimensional (1D harmonic chains can be factored into a Dirac-like equation, leading to antisymmetric modes that have spinor character and therefore non-conventional topology in wave number space. The topology of the elastic waves can be further modified by subjecting phononic structures to externally-induced spatio-temporal modulation of their elastic properties. Such modulations can be actuated through photo-elastic effects, magneto-elastic effects, piezo-electric effects or external mechanical effects. We also uncover an analogy between a combined intrinsic-extrinsic systems composed of a simple one-dimensional harmonic chain coupled to a rigid substrate subjected to a spatio-temporal modulation of the side spring stiffness and the Dirac equation in the presence of an electromagnetic field. The modulation is shown to be able to tune the spinor part of the elastic wave function and therefore its topology. This analogy between classical mechanics and quantum phenomena offers new modalities for developing more complex functions of phononic crystals and acoustic metamaterials.

Solitary waves on nonlinear elastic rods. I

DEFF Research Database (Denmark)

Sørensen, Mads Peter; Christiansen, Peter Leth; Lomdahl, P. S.

1984-01-01

Acoustic waves on elastic rods with circular cross section are governed by improved Boussinesq equations when transverse motion and nonlinearity in the elastic medium are taken into account. Solitary wave solutions to these equations have been found. The present paper treats the interaction betwe...... nonlinearity. The balance between dispersion and nonlinearity in the equation is investigated.......Acoustic waves on elastic rods with circular cross section are governed by improved Boussinesq equations when transverse motion and nonlinearity in the elastic medium are taken into account. Solitary wave solutions to these equations have been found. The present paper treats the interaction between...... the solitary waves numerically. It is demonstrated that the waves behave almost like solitons in agreement with the fact that the improved Boussinesq equations are nearly integrable. Thus three conservation theorems can be derived from the equations. A new subsonic quasibreather is found in the case of a cubic...

Elastic metamaterials for tuning circular polarization of electromagnetic waves.

Science.gov (United States)

Zárate, Yair; Babaee, Sahab; Kang, Sung H; Neshev, Dragomir N; Shadrivov, Ilya V; Bertoldi, Katia; Powell, David A

2016-06-20

Electromagnetic resonators are integrated with advanced elastic material to develop a new type of tunable metamaterial. An electromagnetic-elastic metamaterial able to switch on and off its electromagnetic chiral response is experimentally demonstrated. Such tunability is attained by harnessing the unique buckling properties of auxetic elastic materials (buckliballs) with embedded electromagnetic resonators. In these structures, simple uniaxial compression results in a complex but controlled pattern of deformation, resulting in a shift of its electromagnetic resonance, and in the structure transforming to a chiral state. The concept can be extended to the tuning of three-dimensional materials constructed from the meta-molecules, since all the components twist and deform into the same chiral configuration when compressed.

Common misconceptions about the dynamical theory of crystal lattices: Cauchy relations, lattice potentials and infinite crystals

International Nuclear Information System (INIS)

Elcoro, Luis; Etxebarria, Jesus

2011-01-01

The requirement of rotational invariance for lattice potential energies is investigated. Starting from this condition, it is shown that the Cauchy relations for the elastic constants are fulfilled if the lattice potential is built from pair interactions or when the first-neighbour approximation is adopted. This is seldom recognized in widely used solid-state textbooks. Frequently, pair interaction is even considered to be the most general situation. In addition, it is shown that the demand of rotational invariance in an infinite crystal leads to inconsistencies in the symmetry of the elastic tensor. However, for finite crystals, no problems arise, and the Huang conditions are deduced using exclusively a microscopic approach for the elasticity theory, without making any reference to macroscopic parameters. This work may be useful in both undergraduate and graduate level courses to point out the crudeness of the pair-potential interaction and to explore the limits of the infinite-crystal approximation.

Density functional calculations of elastic properties of portlandite, Ca(OH)(2)

DEFF Research Database (Denmark)

Laugesen, Jakob Lund

2005-01-01

The elastic constants of portlandite, Ca(OH)(2), are calculated by use of density functional theory. A lattice optimization of an infinite (periodic boundary conditions) lattice is performed on which strains are applied. The elastic constants are extracted by minimizing Hooke's law of linear...

Sound radiation quantities arising from a resilient circular radiator

NARCIS (Netherlands)

Aarts, R.M.; Janssen, A.J.E.M.

2009-01-01

Power series expansions in ka are derived for the pressure at the edge of a radiator, the reaction force on the radiator, and the total radiated power arising from a harmonically excited, resilient, flat, circular radiator of radius a in an infinite baffle. The velocity profiles on the radiator are

Quantum wave-packet revivals in circular billiards

International Nuclear Information System (INIS)

Robinett, R.W.; Heppelmann, S.

2002-01-01

We examine the long-term time dependence of Gaussian wave packets in a circular infinite well (billiard) system and find that there are approximate revivals. For the special case of purely m=0 states (central wave packets with no momentum) the revival time is T rev (m=0) =8μR 2 /(ℎ/2π)π, where μ is the mass of the particle, and the revivals are almost exact. For all other wave packets, we find that T rev (m≠0) =(π 2 /2)T rev (m=0) ≅5T rev (m=0) and the nature of the revivals becomes increasingly approximate as the average angular momentum or number of m≠0 states is increased. The dependence of the revival structure on the initial position, energy, and angular momentum of the wave packet and the connection to the energy spectrum is discussed in detail. The results are also compared to two other highly symmetrical two-dimensional infinite well geometries with exact revivals, namely, the square and equilateral triangle billiards. We also show explicitly how the classical periodicity for closed orbits in a circular billiard arises from the energy eigenvalue spectrum, using a WKB analysis

Non-invasive determination of the complete elastic moduli of spider silks

Science.gov (United States)

Koski, Kristie J.; Akhenblit, Paul; McKiernan, Keri; Yarger, Jeffery L.

2013-03-01

Spider silks possess nature’s most exceptional mechanical properties, with unrivalled extensibility and high tensile strength. Unfortunately, our understanding of silks is limited because the complete elastic response has never been measured—leaving a stark lack of essential fundamental information. Using non-invasive, non-destructive Brillouin light scattering, we obtain the entire stiffness tensors (revealing negative Poisson’s ratios), refractive indices, and longitudinal and transverse sound velocities for major and minor ampullate spider silks: Argiope aurantia, Latrodectus hesperus, Nephila clavipes, Peucetia viridans. These results completely quantify the linear elastic response for all possible deformation modes, information unobtainable with traditional stress-strain tests. For completeness, we apply the principles of Brillouin imaging to spatially map the elastic stiffnesses on a spider web without deforming or disrupting the web in a non-invasive, non-contact measurement, finding variation among discrete fibres, junctions and glue spots. Finally, we provide the stiffness changes that occur with supercontraction.

Detailed Monte Carlo simulation of electron elastic scattering

International Nuclear Information System (INIS)

Chakarova, R.

1994-04-01

A detailed Monte Carlo model is described which simulates the transport of electrons penetrating a medium without energy loss. The trajectory of each electron is constructed as a series of successive interaction events - elastic or inelastic scattering. Differential elastic scattering cross sections, elastic and inelastic mean free paths are used to describe the interaction process. It is presumed that the cross sections data are available and the Monte Carlo algorithm does not include their evaluation. Electrons suffering successive elastic collisions are followed until they escape from the medium or (if the absorption is negligible) their path length exceeds a certain value. The inelastic events are thus treated as absorption. The medium geometry is a layered infinite slab. The electron source could be an incident electron beam or electrons created inside the material. The objective is to obtain the angular distribution, the path length and depth distribution and the collision number distribution of electrons emitted through the surface of the medium. The model is applied successfully to electrons with energy between 0.4 and 20 keV reflected from semi-infinite homogeneous materials with different scattering properties. 16 refs, 9 figs

Non-linear elastic deformations

CERN Document Server

Ogden, R W

1997-01-01

Classic in the field covers application of theory of finite elasticity to solution of boundary-value problems, analysis of mechanical properties of solid materials capable of large elastic deformations. Problems. References.

One-dimensional gravity in infinite point distributions

Science.gov (United States)

Gabrielli, A.; Joyce, M.; Sicard, F.

2009-10-01

The dynamics of infinite asymptotically uniform distributions of purely self-gravitating particles in one spatial dimension provides a simple and interesting toy model for the analogous three dimensional problem treated in cosmology. In this paper we focus on a limitation of such models as they have been treated so far in the literature: the force, as it has been specified, is well defined in infinite point distributions only if there is a centre of symmetry (i.e., the definition requires explicitly the breaking of statistical translational invariance). The problem arises because naive background subtraction (due to expansion, or by “Jeans swindle” for the static case), applied as in three dimensions, leaves an unregulated contribution to the force due to surface mass fluctuations. Following a discussion by Kiessling of the Jeans swindle in three dimensions, we show that the problem may be resolved by defining the force in infinite point distributions as the limit of an exponentially screened pair interaction. We show explicitly that this prescription gives a well defined (finite) force acting on particles in a class of perturbed infinite lattices, which are the point processes relevant to cosmological N -body simulations. For identical particles the dynamics of the simplest toy model (without expansion) is equivalent to that of an infinite set of points with inverted harmonic oscillator potentials which bounce elastically when they collide. We discuss and compare with previous results in the literature and present new results for the specific case of this simplest (static) model starting from “shuffled lattice” initial conditions. These show qualitative properties of the evolution (notably its “self-similarity”) like those in the analogous simulations in three dimensions, which in turn resemble those in the expanding universe.

Linear elastic analysis of pavement structure under non-circular loading

CSIR Research Space (South Africa)

Maina, JW

2012-10-01

Full Text Available the development of a method for pavement structural analysis considering both uniform and non-uniform loads acting over a rectangular area. In this approach, three components of displacements, which satisfy Navier’s equations, are expressed using Neuber...

Shells on elastic foundations

International Nuclear Information System (INIS)

Das, Y.C.; Kedia, K.K.

1977-01-01

No realistic analytical work in the area of Shells on Elastic Foundations has been reported in the literature. Various foundation models have been proposed by several authors. These models involve one or more than one parameters to characterise the foundation medium. Some of these models cannot be used to derive the basic equations governing the behaviour of shells on elastic foundations. In the present work, starting from an elastic continuum hypothesis, a mathematical model for foundation has been derived in curvilinear orthogonal coordinates by the help of principle of virtual displacements, treating one of the virtual displacements as known to satisfy certain given conditions at its edge surfaces. In this model, several foundation parameters can be considered and it can also be used for layered medium of both finite and infinite thickness. (Auth.)

Boundary layer flow past a circular cylinder in axial flow

International Nuclear Information System (INIS)

Sawchuk, S.P.; Zamir, M.; Camiletti, S.E.

1985-01-01

This paper discusses a study of the laminar boundary layer on a semi-infinite circular cylinder in axial incompressible flow. Unlike previous studies, the present study investigates a full range of this boundary layer problem to determine skin friction, heat transfer and other integral properties of the boundary layer

Theoretical and numerical treatment of diffraction through a circular aperture

NARCIS (Netherlands)

Bouwkamp, C.J.

1970-01-01

The three-dimensional diffraction of a scalar plane wave through a circular aperture in an infinite plane screen is analyzed and numerically computed for the case of normal incidence. A modified Babinet's principle is formulated, and this is used to find the diffraction of sound by an acoustically

Phase Radiation Characteristics of an Open-Ended Circular Waveguide

DEFF Research Database (Denmark)

Shishkova, A.V.; Pivnenko, Sergiy; Kim, O.S.

2002-01-01

Analytic expressions for phase radiation characteristics of a semi-infinite open-ended circular waveguide regardless of its aperture size and operating frequency have been obtained making use of the rigorous Weinstein's theory. The analysis of phase radiation patterns has been carried out...... for the dominant mode (TE11) as well as for the high order modes TM01 and TE01, both for a single and multimode propagation. The measurement of radiation characteristics of an open-ended circular waveguide has been carried out at the DTU-ESA Spherical Near-Field Antenna Test Facility. It is shown...

Growth-induced axial buckling of a slender elastic filament embedded in an isotropic elastic matrix

KAUST Repository

O'Keeffe, Stephen G.

2013-11-01

We investigate the problem of an axially loaded, isotropic, slender cylinder embedded in a soft, isotropic, outer elastic matrix. The cylinder undergoes uniform axial growth, whilst both the cylinder and the surrounding elastic matrix are confined between two rigid plates, so that this growth results in axial compression of the cylinder. We use two different modelling approaches to estimate the critical axial growth (that is, the amount of axial growth the cylinder is able to sustain before it buckles) and buckling wavelength of the cylinder. The first approach treats the filament and surrounding matrix as a single 3-dimensional elastic body undergoing large deformations, whilst the second approach treats the filament as a planar, elastic rod embedded in an infinite elastic foundation. By comparing the results of these two approaches, we obtain an estimate of the foundation modulus parameter, which characterises the strength of the foundation, in terms of the geometric and material properties of the system. © 2013 Elsevier Ltd. All rights reserved.

Plasmon mediated non-photochemical nucleation of nanoparticles by circularly polarized light

OpenAIRE

Karpov, Victor G.; Grigorchuk, Nicholas I.

2014-01-01

We predict nucleation of pancake shaped metallic nanoparticles having plasmonic frequencies in resonance with a non-absorbed circularly polarized electromagnetic field. We show that the same field can induce nucleation of randomly oriented needle shaped particles. The probabilities of these shapes are estimated vs. field frequency and strength, material parameters, and temperature. This constitutes a quantitative model of non-photochemical laser induced nucleation (NPLIN) consistent with the ...

MHD free convection flow of a visco-elastic (Kuvshiniski type dusty gas through a semi infinite plate moving with velocity decreasing exponentially with time and radiative heat transfer

Directory of Open Access Journals (Sweden)

Om Prakash

2011-06-01

Full Text Available The present paper is concerned with the study of MHD free convective flow of a visco-elastic (Kuvshinski type dusty gas through a porous medium induced by the motion of a semi-infinite flat plate under the influence of radiative heat transfer moving with velocity decreasing exponentially with time. The expressions for velocity distribution of a dusty gas and dust particles, concentration profile and temperature field are obtained. The effect of Schmidt number (Sc, Magnetic field parameter (M and Radiation parameter (N on velocity distribution of dusty gas and dust particles, concentration and temperature distribution are discussed graphically.

High-beta studies with beam-heated, non-circular plasmas in ISX-B

International Nuclear Information System (INIS)

Lazarus, E.A.; Bates, S.C.; Bush, C.E.

1981-01-01

In this paper we describe some preliminary results of high beta studies on ISX-B for mildly D shaped discharges. ISX-B is a modest size tokamak (R 0 = 93 cm, a = 27 cm) equipped with two tangantially-aligned neutral beam injectors giving a total power up to 3 MW. The poloidal coil system allows choice of plasma boundary shapes from circular to elongated (kappa less than or equal to 1.8), with D, elliptical, or inverse D cross sections. The non-circular work discussed here is for kappa approx. = 1.5

Modelling energy and non-energy substitution: A brief survey of elasticities

International Nuclear Information System (INIS)

Frondel, Manuel

2011-01-01

Estimating the degree of substitution between energy and non-energy inputs is the key for any evaluation of environmental and energy policies. Yet, given the variety of substitution elasticities, the central question arises as to which measure would be most appropriate. Apparently, Allen's elasticities of substitution have been the most-used measures in applied production analysis. In line with , this paper argues that cross-price elasticities are preferable for many practical purposes. This conclusion is based on a survey of classical substitution measures, such as those from Allen, Morishima, and McFadden. The survey highlights the fact that cross-price elasticities are their essential ingredients. - Highlights: → Given the large variety of substitution elasticities, the central question arises as to which measure would be most appropriate. Apparently, Allen's elasticities of substitution have been the most-used measures in applied production analysis. → In line with , this paper argues that cross-price elasticities are preferable for many practical purposes. → This conclusion is based on a survey of classical substitution measures, such as those from Allen, Morishima, and McFadden. → The survey also highlights the fact that cross-price elasticities are their essential ingredients.

Infinite permutations vs. infinite words

Directory of Open Access Journals (Sweden)

Anna E. Frid

2011-08-01

Full Text Available I am going to compare well-known properties of infinite words with those of infinite permutations, a new object studied since middle 2000s. Basically, it was Sergey Avgustinovich who invented this notion, although in an early study by Davis et al. permutations appear in a very similar framework as early as in 1977. I am going to tell about periodicity of permutations, their complexity according to several definitions and their automatic properties, that is, about usual parameters of words, now extended to permutations and behaving sometimes similarly to those for words, sometimes not. Another series of results concerns permutations generated by infinite words and their properties. Although this direction of research is young, many people, including two other speakers of this meeting, have participated in it, and I believe that several more topics for further study are really promising.

Quantum wave packet revival in two-dimensional circular quantum wells with position-dependent mass

International Nuclear Information System (INIS)

Schmidt, Alexandre G.M.; Azeredo, Abel D.; Gusso, A.

2008-01-01

We study quantum wave packet revivals on two-dimensional infinite circular quantum wells (CQWs) and circular quantum dots with position-dependent mass (PDM) envisaging a possible experimental realization. We consider CQWs with radially varying mass, addressing particularly the cases where M(r)∝r w with w=1,2, or -2. The two PDM Hamiltonians currently allowed by theory were analyzed and we were able to construct a strong theoretical argument favoring one of them

Shear stresses around circular cylindrical openings

NARCIS (Netherlands)

Hoogenboom, P.C.J.; Van Weelden, C.; Blom, C.M.B.

2010-01-01

In this paper stress concentrations are studied around circular cylindrical openings or voids in a linear elastic continuum. The loading is such that a uniform shear stress occurs in the continuum, which is disturbed by the opening. The shear stress is in the direction of the centre axis of the

Bounds of thermal stability of infinite cylindrical structures with non-uniform internal heat generation

International Nuclear Information System (INIS)

Gadalla, M.A.

1992-01-01

This paper presents an overview analyses of the thermal instability or thermal viability of infinite cylindrical structures with non-linear and non-uniform internal heat generation. The structure may be subjected to different and combined boundary conditions. An analytical solution is obtained for the generalized problem in spite of the non-linearity and the non-homogeneity of the source term. Four case studies with different boundary conditions are presented. The analyses show that the critical parameter for thermal stability may be though of as an altitude of surface below which the cylindrical structure will be thermally stable and performance worthy. The results also show that the bounds of thermal stability of a cylindrical structure system (solid or hollow) is eminently determined by the boundary conditions to which the system is subjected and can significantly alter the life-span of the structure

Infinite Multiplets

Science.gov (United States)

Nambu, Y.

1967-01-01

The main ingredients of the method of infinite multiplets consist of: 1) the use of wave functions with an infinite number of components for describing an infinite tower of discrete states of an isolated system (such as an atom, a nucleus, or a hadron), 2) the use of group theory, instead of dynamical considerations, in determining the properties of the wave functions.

Constitutive relations for non-elastic deformation

International Nuclear Information System (INIS)

Hart, E.W.

1978-01-01

A new class of constitutive equations is described for non-elastic deformation of metals. The relations are embodied in a model that has had considerable experimental investigation. The model employs two deformation state variables of which one is a scalar hardness variable and the other is a stored anelastic strain. The description is entirely in terms of real time strain rates. The model and its experimental background is discussed. The relationship to mechanical calculations and a possible extension to radiation environment is also considered. (Auth.)

Dynamic Response of Underground Circular Lining Tunnels Subjected to Incident P Waves

Directory of Open Access Journals (Sweden)

Hua Xu

2014-01-01

Full Text Available Dynamic stress concentration in tunnels and underground structures during earthquakes often leads to serious structural damage. A series solution of wave equation for dynamic response of underground circular lining tunnels subjected to incident plane P waves is presented by Fourier-Bessel series expansion method in this paper. The deformation and stress fields of the whole medium of surrounding rock and tunnel were obtained by solving the equations of seismic wave propagation in an elastic half space. Based on the assumption of a large circular arc, a series of solutions for dynamic stress were deduced by using a wave function expansion approach for a circular lining tunnel in an elastic half space rock medium subjected to incident plane P waves. Then, the dynamic response of the circular lining tunnel was obtained by solving a series of algebraic equations after imposing its boundary conditions for displacement and stress of the circular lining tunnel. The effects of different factors on circular lining rock tunnels, including incident frequency, incident angle, buried depth, rock conditions, and lining stiffness, were derived and several application examples are presented. The results may provide a good reference for studies on the dynamic response and aseismic design of tunnels and underground structures.

Quantum wave packet revival in two-dimensional circular quantum wells with position-dependent mass

Energy Technology Data Exchange (ETDEWEB)

Schmidt, Alexandre G.M. [Departamento de Ciencias Exatas, Polo Universitario de Volta Redonda-Universidade Federal Fluminense, Av. dos Trabalhadores 420, Volta Redonda RJ, CEP 27255-125 (Brazil)], E-mail: agmschmidt@gmail.com; Azeredo, Abel D. [Departamento de Fisica-Universidade Federal de Roraima, Av. Cap. Ene Garcez 2413, Boa Vista RR, CEP 69304-000 (Brazil)], E-mail: aazeredo@gmail.com; Gusso, A. [Departamento de Ciencias Exatas e Tecnologicas-Universidade Estadual de Santa Cruz, km 16 Rodovia Ilheus-Itabuna, Ilheus BA, CEP 45662-000 (Brazil)], E-mail: agusso@uesc.br

2008-04-14

We study quantum wave packet revivals on two-dimensional infinite circular quantum wells (CQWs) and circular quantum dots with position-dependent mass (PDM) envisaging a possible experimental realization. We consider CQWs with radially varying mass, addressing particularly the cases where M(r){proportional_to}r{sup w} with w=1,2, or -2. The two PDM Hamiltonians currently allowed by theory were analyzed and we were able to construct a strong theoretical argument favoring one of them.

Elasticity in Elastics-An in-vitro study.

Science.gov (United States)

Kamisetty, Supradeep Kumar; Nimagadda, Chakrapani; Begam, Madhoom Ponnachi; Nalamotu, Raghuveer; Srivastav, Trilok; Gs, Shwetha

2014-04-01

Orthodontic tooth movement results from application of forces to teeth. Elastics in orthodontics have been used both intra-orally and extra- orally to a great effect. Their use, combined with good patient co-operation provides the clinician with the ability to correct both anteroposterior and vertical discrepancies. Force decay over a period of time is a major problem in the clinical usage of latex elastics and synthetic elastomers. This loss of force makes it difficult for the clinician to determine the actual force transmitted to the dentition. It's the intent of the clinician to maintain optimal force values over desired period of time. The majority of the orthodontic elastics on the market are latex elastics. Since the early 1990s, synthetic products have been offered in the market for latex-sensitive patients and are sold as nonlatex elastics. There is limited information on the risk that latex elastics may pose to patients. Some have estimated that 0.12-6% of the general population and 6.2% of dental professionals have hypersensitivity to latex protein. There are some reported cases of adverse reactions to latex in the orthodontic population but these are very limited to date. Although the risk is not yet clear, it would still be inadvisable to prescribe latex elastics to a patient with a known latex allergy. To compare the in-vitro performance of latex and non latex elastics. Samples of 0.25 inch, latex and non latex elastics (light, medium, heavy elastics) were obtained from three manufacturers (Forestadent, GAC, Glenroe) and a sample size of ten elastics per group was tested. The properties tested included cross sectional area, internal diameter, initial force generated by the elastics, breaking force and the force relaxation for the different types of elastics. Force relaxation testing involved stretching the elastics to three times marketed internal diameter (19.05 mm) and measuring force level at intervals over a period of 48 hours. The data were

Analysis of HD Journal Bearings Considering Elastic Deformation and Non-Newtonian Rabinowitsch Fluid Model

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J. Javorova

2016-06-01

Full Text Available The purpose of this paper is to study the performance of a finite length journal bearing, taking into account effects of non-Newtonian Rabinowitsch flow rheology and elastic deformations of the bearing liner. According to the Rabinowitsch fluid model, the cubic-stress constitutive equation is used to account for the non-Newtonian effects of pseudoplastic and dilatant lubricants. Integrating the continuity equation across the film, the nonlinear non-Newtonian Reynolds-type equation is derived. The elasticity part of the problem is solved on the base of Vlassov model of an elastic foundation. The numerical solution of the modified Reynolds equation is carried out by using FDM with over-relaxation technique. The results for steady state bearing performance characteristics have been calculated for various values of nonlinear factor and elasticity parameters. It was concluded that in comparison with the Newtonian lubricants, higher values of film pressure and load carrying capacity have been obtained for dilatant lubricants, while the case was reversed for pseudoplastic lubricants.

Elastic models for the non-Arrhenius relaxation time of glass-forming liquids

DEFF Research Database (Denmark)

Dyre, Jeppe

We first review the phenomenology of viscous liquids and the standard models used for explaining the non-Arrhenius average relaxation time. Then the focus is turned to the so-called elastic models, arguing that these models are all equivalent in the Einstein approximation (where the short-time...... elastic properties are all determined by just one effective, temperature-dependent force constant). We finally discuss the connection between the elastic models and two well-established research fields of condensed-matter physics: point defects in crystals and solid-state diffusion....

Elastic models for the Non-Arrhenius Relaxation Time of Glass-Forming Liquids

DEFF Research Database (Denmark)

Dyre, J. C.

2006-01-01

We first review the phenomenology of viscous liquids and the standard models used for explaining the non-Arrhenius average relaxation time. Then the focus is turned to the so-called elastic models, arguing that these models are all equivalent in the Einstein approximation (where the short-time...... elastic properties are all determined by just one effective, temperature-dependent force constant). We finally discuss the connection between the elastic models and two well-established research fields of condensed-matter physics: point defects in crystals and solid-state diffusion....

Surface properties of semi-infinite Fermi systems

International Nuclear Information System (INIS)

Campi, X.; Stringari, S.

1979-10-01

A functional relation between the kinetic energy density and the total density is used to analyse the surface properties of semi-infinite Fermi systems. One find an explicit expression for the surface thickness in which the role of the infinite matter compressibility, binding energy and non-locality effects is clearly shown. The method, which holds both for nuclear and electronic systems (liquid metals), yields a very simple relation between the surface thickness and the surface energy

The Influence of Flexibility Coefficient on the Size of Internal Forces and Deformations in Circular Plates on Elastic Medium

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Şandru Mirela

2016-09-01

Full Text Available This paper presents an analytical study which deals with the behavior of the circular plates in bending theory, considering the soil-structure interaction under Winkler's hypothesis. It was intended to illustrate the variation of internal forces and deformations according to the flexibility coefficient of plates considering three models: a fixed solid circular plate subjected to a uniformly distributed load, a fixed solid circular plate acted by a displacement applied on the exterior contour and a solid plate subjected to a temperature gradient. For this study the computation relations were written as a product between a dimensional and a non-dimensional factor, the last one indicating the variation of internal forces and deformations. For each type of action there are presented results obtained using the finite element method to illustrate the differences between this method and the analytical computation.

Backward Stochastic Riccati Equations and Infinite Horizon L-Q Optimal Control with Infinite Dimensional State Space and Random Coefficients

International Nuclear Information System (INIS)

Guatteri, Giuseppina; Tessitore, Gianmario

2008-01-01

We study the Riccati equation arising in a class of quadratic optimal control problems with infinite dimensional stochastic differential state equation and infinite horizon cost functional. We allow the coefficients, both in the state equation and in the cost, to be random.In such a context backward stochastic Riccati equations are backward stochastic differential equations in the whole positive real axis that involve quadratic non-linearities and take values in a non-Hilbertian space. We prove existence of a minimal non-negative solution and, under additional assumptions, its uniqueness. We show that such a solution allows to perform the synthesis of the optimal control and investigate its attractivity properties. Finally the case where the coefficients are stationary is addressed and an example concerning a controlled wave equation in random media is proposed

The Effect of Non-Circular Bearing Shapes in Hydrodynamic Journal Bearings on the Vibration Behavior of Turbocharger Structures

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Lukas Bernhauser

2017-03-01

Full Text Available Increasing quality demands of combustion engines require, amongst others, improvements of the engine’s acoustics and all (subcomponents mounted to the latter. A significant impact to the audible tonal noise spectrum results from the vibratory motions of fast-rotating turbocharger rotor systems in multiple hydrodynamic bearings such as floating bearing rings. Particularly, the study of self-excited non-linear vibrations of the rotor-bearing systems is crucial for the understanding, prevention or reduction of the noise and, consequently, for a sustainable engine acoustics development. This work presents an efficient modeling approach for the investigation, optimization, and design improvement of complex turbocharger rotors in hydrodynamic journal bearings, including floating bearing rings with circular and non-circular bearing geometries. The capability of tonal non-synchronous vibration prevention using non-circular bearing shapes is demonstrated with dynamic run-up simulations of the presented model. These findings and the performance of our model are compared and validated with results of a classical Laval/Jeffcott rotor-bearing model and a specific turbocharger model found in the literature. It is shown that the presented simulation method yields fast and accurate results and furthermore, that non-circular bearing shapes are an effective measure to reduce or even prevent self-excited tonal noise.

Electron's anomalous magnetic-moment effects on electron-hydrogen elastic collisions in the presence of a circularly polarized laser field

International Nuclear Information System (INIS)

Elhandi, S.; Taj, S.; Attaourti, Y.; Manaut, B.; Oufni, L.

2010-01-01

The effect of the electron's anomalous magnetic moment on the relativistic electronic dressing for the process of electron-hydrogen atom elastic collisions is investigated. We consider a laser field with circular polarization and various electric field strengths. The Dirac-Volkov states taking into account this anomaly are used to describe the process in the first order of perturbation theory. The correlation between the terms coming from this anomaly and the electric field strength gives rise to the strong dependence of the spinor part of the differential cross section (DCS) with respect to these terms. A detailed study has been devoted to the nonrelativistic regime as well as the moderate relativistic regime. Some aspects of this dependence as well as the dynamical behavior of the DCS in the relativistic regime have been addressed.

Dynamic energy release rate in couple-stress elasticity

International Nuclear Information System (INIS)

Morini, L; Piccolroaz, A; Mishuris, G

2013-01-01

This paper is concerned with energy release rate for dynamic steady state crack problems in elastic materials with microstructures. A Mode III semi-infinite crack subject to loading applied on the crack surfaces is considered. The micropolar behaviour of the material is described by the theory of couple-stress elasticity developed by Koiter. A general expression for the dynamic J-integral including both traslational and micro-rotational inertial contributions is derived, and the conservation of this integral on a path surrounding the crack tip is demonstrated

Asymptotic stability boundaries of ballooning modes in circular tokamaks

International Nuclear Information System (INIS)

Chen, L.; Bondeson, A.; Chance, M.S.

1987-06-01

The model ballooning mode equation of Connor, Hastie, and Taylor for large-aspect-ratio circular tokamaks is analyzed in the limit of large pressure gradient, and corresponding expressions for stability boundaries are derived. In particular, it is found that for a fixed radial wave number, there exists an infinite sequence of unstable bands, and that minimizing over the radial wave numbers leads to asymptotic merging between the neighboring bands

Postbuckling of magneto-electro-elastic CNT-MT composite nanotubes resting on a nonlinear elastic medium in a non-uniform thermal environment

Science.gov (United States)

Kamali, M.; Shamsi, M.; Saidi, A. R.

2018-03-01

As a first endeavor, the effect of nonlinear elastic foundation on the postbuckling behavior of smart magneto-electro-elastic (MEE) composite nanotubes is investigated. The composite nanotube is affected by a non-uniform thermal environment. A typical MEE composite nanotube consists of microtubules (MTs) and carbon nanotubes (CNTs) with a MEE cylindrical nanoshell for smart control. It is assumed that the nanoscale layers of the system are coupled by a polymer matrix or filament network depending on the application. In addition to thermal loads, magneto-electro-mechanical loads are applied to the composite nanostructure. Length scale effects are taken into account using the nonlocal elasticity theory. The principle of virtual work and von Karman's relations are used to derive the nonlinear governing differential equations of MEE CNT-MT nanotubes. Using Galerkin's method, nonlinear critical buckling loads are determined. Various types of non-uniform temperature distribution in the radial direction are considered. Finally, the effects of various parameters such as the nonlinear constant of elastic medium, thermal loading factor and small scale coefficient on the postbuckling of MEE CNT-MT nanotubes are studied.

On solution of the integral equations for the potential problems of two circular-strips

Directory of Open Access Journals (Sweden)

C. Sampath

1988-01-01

Dirichlet and Newmann boundary value problems of two equal infinite coaxial circular strips in various branches of potential theory. For illustration, these solutions are applied to solve some boundary value problems in electrostatics, hydrodynamics, and expressions for the physical quantities of interest are derived.

Line-focus acoustic microscopy of Ti-6242 α/β single colony: determination of elastic constants

International Nuclear Information System (INIS)

Kim, J.-Y.; Yakovlev, V.; Rokhlin, S.I.

2002-01-01

Time-resolved line-focus acoustic microscopy is performed for determining elastic constants of Ti-6242 α/β-single colony and Ti-6 α-phase single crystal. Surface acoustic wave (SAW) velocities are obtained as a function of the propagation angle from measured time-delays of SAW signals. The propagation of surface waves in a semi-infinite half space formed by anisotropic layers inclined arbitrarily to the sample surface is studied to model a quasi-random lamellar structure of the Ti-6242 α/β-single colony. Effective elastic constants of the multilayered structure are derived and verified through the comparison with exact ones, based on which SAW velocities in non-principal planes are calculated. Effective and constituent elastic constants of the α/β-single colony and the α-phase single crystal are inversely determined from the measured and calculated SAW velocities. The α- and β-phase elastic constants from the α/β-single colony so determined are compared with those from the α-single crystal and data in the literature

Hydroelastic Oscillations of a Circular Plate, Resting on Winkler Foundation

Science.gov (United States)

Kondratov, D. V.; Mogilevich, L. I.; Popov, V. S.; Popova, A. A.

2018-01-01

The forced hydroelastic oscillations of a circular plate resting on elastic foundation are investigated. The oscillations are caused by a stamp vibration under interaction with a plate through a thin layer of viscous incompressible liquid. The axis-symmetric problem for the regime of the steady-state harmonic oscillations is considered. On the basis of hydroelasticity problem solution the laws of plate deflection and pressure in the liquid are found. The functions of the amplitudes deflection distribution and liquid pressure along the plate are constructed. The presented mathematical model provides for investigating viscous liquid layer interaction dynamics with a circular plate resting on an elastic foundation. The above-mentioned model makes it possible to define the plate oscillations resonance frequencies and the corresponding amplitudes of deflection and liquid pressure, as well.

Dynamic Interaction of Interfacial Point Source Loading and Cylinder in an Elastic Quarter with Anti-plane Shear

Science.gov (United States)

Chun, Gao; Hui, Qi; Nan, Pan Xiang; Bo, Zhao Yuan

2017-07-01

Theoretical steady state solution of a semi-circular cylinder impacted by an anti-plane point loading in a vertical bound of an elastic quarter is formulated in this paper through using image method and wave function expansion series. The elastic quarter is extended as a half space, and the semi-circular interfacial cylinder is extended as a circular cylinder. Displacement field is constructed as series of Fourier-Hankel and Fourier-Bessel wave functions. At last, circular boundary is expanded as Fourier series to determine coefficients of wave function. Numerical results show that material parameters have two widely divergent effects on the radial and circumferential dynamic stress distribution.

Analytical solution for the transient wave propagation of a buried cylindrical P-wave line source in a semi-infinite elastic medium with a fluid surface layer

Science.gov (United States)

Shan, Zhendong; Ling, Daosheng

2018-02-01

This article develops an analytical solution for the transient wave propagation of a cylindrical P-wave line source in a semi-infinite elastic solid with a fluid layer. The analytical solution is presented in a simple closed form in which each term represents a transient physical wave. The Scholte equation is derived, through which the Scholte wave velocity can be determined. The Scholte wave is the wave that propagates along the interface between the fluid and solid. To develop the analytical solution, the wave fields in the fluid and solid are defined, their analytical solutions in the Laplace domain are derived using the boundary and interface conditions, and the solutions are then decomposed into series form according to the power series expansion method. Each item of the series solution has a clear physical meaning and represents a transient wave path. Finally, by applying Cagniard's method and the convolution theorem, the analytical solutions are transformed into the time domain. Numerical examples are provided to illustrate some interesting features in the fluid layer, the interface and the semi-infinite solid. When the P-wave velocity in the fluid is higher than that in the solid, two head waves in the solid, one head wave in the fluid and a Scholte wave at the interface are observed for the cylindrical P-wave line source.

Microstructural evolution in inhomogeneous elastic media

International Nuclear Information System (INIS)

Jou, H.J.; Leo, P.H.; Lowengrub, J.S.

1997-01-01

We simulate the diffusional evolution of microstructures produced by solid state diffusional transformations in elastically stressed binary alloys in two dimensions. The microstructure consists of arbitrarily shaped precipitates embedded coherently in an infinite matrix. The precipitate and matrix are taken to be elastically isotropic, although they may have different elastic constants (elastically inhomogeneous). Both far-field applied strains and mismatch strains between the phases are considered. The diffusion and elastic fields are calculated using the boundary integral method, together with a small scale preconditioner to remove ill-conditioning. The precipitate-matrix interfaces are tracked using a nonstiff time updating method. The numerical method is spectrally accurate and efficient. Simulations of a single precipitate indicate that precipitate shapes depend strongly on the mass flux into the system as well as on the elastic fields. Growing shapes (positive mass flux) are dendritic while equilibrium shapes (zero mass flux) are squarish. Simulations of multiparticle systems show complicated interactions between precipitate morphology and the overall development of microstructure (i.e., precipitate alignment, translation, merging, and coarsening). In both single and multiple particle simulations, the details of the microstructural evolution depend strongly o the elastic inhomogeneity, misfit strain, and applied fields. 57 refs., 24 figs

Elastic field of approaching dislocation loop in isotropic bimaterial

International Nuclear Information System (INIS)

Wu, Wenwang; Xu, Shucai; Zhang, Jinhuan; Xia, Re; Qian, Guian

2015-01-01

A semi-analytical solution is developed for calculating interface traction stress (ITS) fields due to elastic modulus mismatch across the interface plane of isotropic perfectly bounded bimaterial system. Based on the semi-analytical approaches developed, ITS is used to correct the bulk elastic field of dislocation loop within infinite homogenous medium, and to produce continuous displacement and stress fields across the perfectly-bounded interface. Firstly, calculation examples of dislocation loops in Al–Cu bimaterial system are performed to demonstrate the efficiency of the developed semi-analytical approach; Then, the elastic fields of dislocation loops in twinning Cu and Cu–Nb bimaterial are analyzed; Finally, the effect of modulus mismatch across interface plane on the elastic field of bimaterial system is investigated, it is found that modulus mismatch has a drastic impact on the elastic fields of dislocation loops within bimaterial system. (paper)

Non-linear entropy functionals and a characteristic invariant of symmetry group actions on infinite quantum systems

International Nuclear Information System (INIS)

Hudetz, T.

1989-01-01

We review the development of the non-Abelian generalization of the Kolmogorov-Sinai(KS) entropy invariant, as initated by Connes and Stormer and completed by Connes, Narnhofer and Thirring only recently. As an introduction and motivation, the classical KS theory is reformulated in terms of Abelian W * -algebras. Finally, we describe simple physical applications of the developed characteristic invariant to space-time symmetry group actions on infinite quantum systems. 42 refs. (Author)

Identification of Functional Clusters in the Striatum Using Infinite Relational Modeling

DEFF Research Database (Denmark)

Andersen, Kasper Winther; Madsen, Kristoffer Hougaard; Siebner, Hartwig

2011-01-01

In this paper we investigate how the Infinite Relational Model can be used to infer functional groupings of the human striatum using resting state fMRI data from 30 healthy subjects. The Infinite Relational Model is a non-parametric Bayesian method for infering community structure in complex netw...... and non-links in the graphs as missing. We find that the model is performing well above chance for all subjects....

The effect of the multi-pass non-circular drawing sequence on mechanical properties and microstructure evolution of low-carbon steel

International Nuclear Information System (INIS)

Lee, Jung Wan; Baek, Hyun Moo; Hwang, Sun Kwang; Son, Il-Heon; Bae, Chul Min; Im, Yong-Taek

2014-01-01

Highlights: • A multi-pass non-circular drawing sequence is proposed to make high-strength wires. • The sequence was designed and applied for a low-carbon steel wire up to the 10th pass. • Many LAGBs and small grain size of the wire produced by the sequence were obtained. • High plastic deformation was imposed on the wire, resulting in grain refinement. • The sequence made fine-grained wires with improved UTS, ductility and fatigue life. - Abstract: In this study, the multi-pass non-circular drawing sequence was investigated for manufacturing high-strength wires with better ductility in a simple continuous way without adding additional alloys and heat treatment considering the effect of microstructure evolution and die geometry of the sequence on the mechanical properties of low-carbon steel during the process. For this purpose, the non-circular drawing sequence was designed and applied up to the 10th pass at room temperature. Mechanical properties and microstructure evolution of the specimen processed by the sequence were investigated by tension, Vickers micro-hardness, electron backscattering diffraction (EBSD), and fatigue tests compared with those for the conventional wire-drawing process. From the EBSD results, the higher low angle grain boundaries length per unit area and smaller average grain size of the specimen processed by the non-circular drawing sequence were obtained than those of the specimen processed by the wire-drawing process for the 8th pass. These results indicated that more plastic deformation was imposed in the material by the non-circular drawing sequence, resulting in grain refinement of the deformed specimen compared to the wire-drawing process. It is demonstrated that the multi-pass non-circular drawing sequence could be beneficial in producing fine-grained wires with improved ultimate tensile strength, ductility, and fatigue property by simply changing drawing dies geometry of the conventional wire-drawing process

Thermal effects on the stability of circular graphene sheets via nonlocal continuum mechanics

Directory of Open Access Journals (Sweden)

Saeid Reza Asemi

Full Text Available Recently, graphene sheets have shown significant potential for environmental engineering applications such as wastewater treatment. Different non-classical theories have been used for modeling of such nano-sized systems to take account of the effect of small length scale. Among all size-dependent theories, the nonlocal elasticity theory has been commonly used to examine the stability of nano-sized structures. Some research works have been reported about the mechanical behavior of rectangular nanoplates with the consideration of thermal effects. However, in comparison with the rectangular graphene sheets, research works about the nanoplates of circular shape are very limited, especially for the buckling properties with thermal effects. Hence, in this paper, an axisymmetric buckling analysis of circular single-layered graphene sheets (SLGS is presented by decoupling the nonlocal equations of Eringen theory. Constitutive relations are modified to describe the nonlocal effects. The governing equations are derived using equilibrium equations of the circular plate in polar coordinates. Numerical solutions for buckling loads are computed using Galerkin method. It is shown that nonlocal effects play an important role in the buckling of circular nanoplates. The effects of the small scale on the buckling loads considering various parameters such as the radius of the plate, radius-to-thickness ratio, temperature change and mode numbers are investigated.

Underwater Shock Response of Circular HSLA Steel Plates

Directory of Open Access Journals (Sweden)

R. Rajendran

2000-01-01

Full Text Available Studies on shock response of circular plates subjected to underwater explosion is of interest to ship designers. Non-contact underwater explosion experiments were carried out on air backed circular High Strength Low Alloy (HSLA steel plates of 4 mm thickness and 290 mm diameter. The experiments were carried out in two phases. In the first phase, strain gauges were fixed at intervals of 30 mm from the centre of the plate and strains were recorded for the shock intensity gradually increasing to yielding. Semi-analytical models were derived for the elastic strain prediction which showed good agreement with the experiments. Dynamic yield stress and the shock factor for yielding were established. In the second phase, individual plates were subjected to increasing shock severity until fracture and the apex bulge depth and the thickness strains were measured. Empirical models were derived to predict the plastic deformation which were validated through a fresh set of experiments. Analysis of the fractured surface by visual examination showed that there was slant fracture indicating ductile mode of failure and the same was corroborated by Scanning Electron Microscopic (SEM examination.

Circular defects detection in welded joints using circular hough transform

International Nuclear Information System (INIS)

Hafizal Yazid; Mohd Harun; Shukri Mohd; Abdul Aziz Mohamed; Shaharudin Sayuti; Muhamad Daud

2007-01-01

Conventional radiography is one of the common non-destructive testing which employs manual image interpretation. The interpretation is very subjective and depends much on the inspector experience and working conditions. It is therefore useful to have pattern recognition system in order to assist human interpreter in evaluating the quality of the radiograph sample, especially radiographic image of welded joint. This paper describes a system to detect circular discontinuities that is present in the joints. The system utilizes together 2 different algorithms, which is separability filter to identify the best object candidate and Circular Hough Transform to detect the present of circular shape. The result of the experiment shows a promising output in recognition of circular discontinuities in a radiographic image. This is based on 81.82-100% of radiography film with successful circular detection by using template movement of 10 pixels. (author)

Nonlinear electroelastic deformations of dielectric elastomer composites: II - Non-Gaussian elastic dielectrics

Science.gov (United States)

Lefèvre, Victor; Lopez-Pamies, Oscar

2017-02-01

This paper presents an analytical framework to construct approximate homogenization solutions for the macroscopic elastic dielectric response - under finite deformations and finite electric fields - of dielectric elastomer composites with two-phase isotropic particulate microstructures. The central idea consists in employing the homogenization solution derived in Part I of this work for ideal elastic dielectric composites within the context of a nonlinear comparison medium method - this is derived as an extension of the comparison medium method of Lopez-Pamies et al. (2013) in nonlinear elastostatics to the coupled realm of nonlinear electroelastostatics - to generate in turn a corresponding solution for composite materials with non-ideal elastic dielectric constituents. Complementary to this analytical framework, a hybrid finite-element formulation to construct homogenization solutions numerically (in three dimensions) is also presented. The proposed analytical framework is utilized to work out a general approximate homogenization solution for non-Gaussian dielectric elastomers filled with nonlinear elastic dielectric particles that may exhibit polarization saturation. The solution applies to arbitrary (non-percolative) isotropic distributions of filler particles. By construction, it is exact in the limit of small deformations and moderate electric fields. For finite deformations and finite electric fields, its accuracy is demonstrated by means of direct comparisons with finite-element solutions. Aimed at gaining physical insight into the extreme enhancement in electrostriction properties displayed by emerging dielectric elastomer composites, various cases wherein the filler particles are of poly- and mono-disperse sizes and exhibit different types of elastic dielectric behavior are discussed in detail. Contrary to an initial conjecture in the literature, it is found (inter alia) that the isotropic addition of a small volume fraction of stiff (semi

Optimal control of coupled parabolic-hyperbolic non-autonomous PDEs: infinite-dimensional state-space approach

Science.gov (United States)

Aksikas, I.; Moghadam, A. Alizadeh; Forbes, J. F.

2018-04-01

This paper deals with the design of an optimal state-feedback linear-quadratic (LQ) controller for a system of coupled parabolic-hypebolic non-autonomous partial differential equations (PDEs). The infinite-dimensional state space representation and the corresponding operator Riccati differential equation are used to solve the control problem. Dynamical properties of the coupled system of interest are analysed to guarantee the existence and uniqueness of the solution of the LQ-optimal control problem and also to guarantee the exponential stability of the closed-loop system. Thanks to the eigenvalues and eigenfunctions of the parabolic operator and also the fact that the hyperbolic-associated operator Riccati differential equation can be converted to a scalar Riccati PDE, an algorithm to solve the LQ control problem has been presented. The results are applied to a non-isothermal packed-bed catalytic reactor. The LQ optimal controller designed in the early portion of the paper is implemented for the original non-linear model. Numerical simulations are performed to show the controller performances.

Justification of the Shape of a Non-Circular Cross-Section for Drilling With a Roller Cutter

Science.gov (United States)

Buyalich, Gennady; Husnutdinov, Mikhail

2017-11-01

The parameters of the shape of non-circular cross-section affect not only the process of blasting, but also the design of the tool and the process of drilling as well. In the conditions of open-pit mining, it is reasonable to use a roller cutter to produce a non-circular cross-section of blasting holes. With regard to the roller cutter, the impact of the cross-section shape on the oscillations of the axial force arising upon its rotation is determined. It is determined that a polygonal shape with rounded comers of the borehole walls connections and their convex shape, which ensures a smaller range of the total axial force and the torque deflecting the bit from the axis of its rotation is the rational form of the non-circular cross-section of the borehole in terms of bit design. It has been shown that the ratio of the number of cutters to the number of borehole corners must be taken into account when justifying the shape of the cross-section, both from the point of view of the effectiveness of the explosion action and from the point of view of the rational design of the bit.

Towards an exact theory of linear absorbance and circular dichroism of pigment-protein complexes: Importance of non-secular contributions

International Nuclear Information System (INIS)

Dinh, Thanh-Chung; Renger, Thomas

2015-01-01

A challenge for the theory of optical spectra of pigment-protein complexes is the equal strength of the pigment-pigment and the pigment-protein couplings. Treating both on an equal footing so far can only be managed by numerically costly approaches. Here, we exploit recent results on a normal mode analysis derived spectral density that revealed the dominance of the diagonal matrix elements of the exciton-vibrational coupling in the exciton state representation. We use a cumulant expansion technique that treats the diagonal parts exactly, includes an infinite summation of the off-diagonal parts in secular and Markov approximations, and provides a systematic perturbative way to include non-secular and non-Markov corrections. The theory is applied to a model dimer and to chlorophyll (Chl) a and Chl b homodimers of the reconstituted water-soluble chlorophyll-binding protein (WSCP) from cauliflower. The model calculations reveal that the non-secular/non-Markov effects redistribute oscillator strength from the strong to the weak exciton transition in absorbance and they diminish the rotational strength of the exciton transitions in circular dichroism. The magnitude of these corrections is in a few percent range of the overall signal, providing a quantitative explanation of the success of time-local convolution-less density matrix theory applied earlier. A close examination of the optical spectra of Chl a and Chl b homodimers in WSCP suggests that the opening angle between Q y transition dipole moments in Chl b homodimers is larger by about 9 ∘ than for Chl a homodimers for which a crystal structure of a related WSCP complex exists. It remains to be investigated whether this change is due to a different mutual geometry of the pigments or due to the different electronic structures of Chl a and Chl b

Towards an exact theory of linear absorbance and circular dichroism of pigment-protein complexes: Importance of non-secular contributions

Energy Technology Data Exchange (ETDEWEB)

Dinh, Thanh-Chung; Renger, Thomas, E-mail: thomas.renger@jku.at [Institut für Theoretische Physik, Johannes Kepler University Linz, Altenberger Str. 69, 4040 Linz (Austria)

2015-01-21

A challenge for the theory of optical spectra of pigment-protein complexes is the equal strength of the pigment-pigment and the pigment-protein couplings. Treating both on an equal footing so far can only be managed by numerically costly approaches. Here, we exploit recent results on a normal mode analysis derived spectral density that revealed the dominance of the diagonal matrix elements of the exciton-vibrational coupling in the exciton state representation. We use a cumulant expansion technique that treats the diagonal parts exactly, includes an infinite summation of the off-diagonal parts in secular and Markov approximations, and provides a systematic perturbative way to include non-secular and non-Markov corrections. The theory is applied to a model dimer and to chlorophyll (Chl) a and Chl b homodimers of the reconstituted water-soluble chlorophyll-binding protein (WSCP) from cauliflower. The model calculations reveal that the non-secular/non-Markov effects redistribute oscillator strength from the strong to the weak exciton transition in absorbance and they diminish the rotational strength of the exciton transitions in circular dichroism. The magnitude of these corrections is in a few percent range of the overall signal, providing a quantitative explanation of the success of time-local convolution-less density matrix theory applied earlier. A close examination of the optical spectra of Chl a and Chl b homodimers in WSCP suggests that the opening angle between Q{sub y} transition dipole moments in Chl b homodimers is larger by about 9{sup ∘} than for Chl a homodimers for which a crystal structure of a related WSCP complex exists. It remains to be investigated whether this change is due to a different mutual geometry of the pigments or due to the different electronic structures of Chl a and Chl b.

Bulk-mediated surface diffusion: non-Markovian desorption and biased behaviour in an infinite system

International Nuclear Information System (INIS)

Revelli, Jorge A; Budde, Carlos E; Wio, Horacio S

2005-01-01

We analyse the dynamics of adsorbed molecules within the bulk-mediated surface diffusion framework. We consider that the particle's desorption mechanism is characterized by a non-Markovian process, while the particle's adsorption and its motion in the bulk are governed by Markovian dynamics, and include the effect of an external field in the form of a bias in the normal motion to the surface. We study this system for the diffusion of particles in a semi-infinite lattice, analysing the conditional probability to find the system on the reference absorptive plane as well as the surface dispersion as functions of time. The agreement between numerical and analytical asymptotic results is discussed

Surface excess elasticity of gold: Ab initio coefficients and impact on the effective elastic response of nanowires

International Nuclear Information System (INIS)

Elsner, B.A.M.; Müller, S.; Bargmann, S.; Weissmüller, J.

2017-01-01

Predicting the influence of the surface on the effective elastic properties of nanoscale structures and nanomaterials remains a challenge, which we here address on both levels, continuum and atomic. Density Functional Theory (DFT) computation at the atomic level yields the first reliable surface excess elastic parameters for the (111) and (001) surfaces of gold. At the continuum level, we derive closed-form expressions for the effective elastic behavior that can be combined with the DFT-derived excess elastic parameters to obtain the effective axial, torsion, and bending stiffness of circular nanowires with surface excess elasticity. The two approaches use different reference frames, and we emphasize the need for consistent stress definitions and for conversion between the separate stress measures when transferring results between the approaches. We present excess elastic parameters separately for Cauchy and 2 nd Piola-Kirchhoff stresses, demonstrating that the conversion substantially modifies their numerical value and may even invert their sign. The results afford an assessment of the contribution of the surface excess elastic parameters to the effective elastic response of nanoscale beams or wires. This assessment sheds doubt on earlier suggestions relating experimental observations of an effective stiffening or softening at small size to the excess elasticity of clean surfaces.

On infinite walls in deformation quantization

International Nuclear Information System (INIS)

Kryukov, S.; Walton, M.A.

2005-01-01

We examine the deformation quantization of a single particle moving in one dimension (i) in the presence of an infinite potential wall (ii) confined by an infinite square well, and (iii) bound by a delta function potential energy. In deformation quantization, considered as an autonomous formulation of quantum mechanics, the Wigner function of stationary states must be found by solving the so-called *-genvalue ('stargenvalue') equation for the Hamiltonian. For the cases considered here, this pseudo-differential equation is difficult to solve directly, without an ad hoc modification of the potential. Here we treat the infinite wall as the limit of a solvable exponential potential. Before the limit is taken, the corresponding *-genvalue equation involves the Wigner function at momenta translated by imaginary amounts. We show that it can be converted to a partial differential equation, however, with a well-defined limit. We demonstrate that the Wigner functions calculated from the standard Schroedinger wave functions satisfy the resulting new equation. Finally, we show how our results may be adapted to allow for the presence of another, non-singular part in the potential

Comparison principle for impulsive functional differential equations with infinite delays and applications

Science.gov (United States)

Li, Xiaodi; Shen, Jianhua; Akca, Haydar; Rakkiyappan, R.

2018-04-01

We introduce the Razumikhin technique to comparison principle and establish some comparison results for impulsive functional differential equations (IFDEs) with infinite delays, where the infinite delays may be infinite time-varying delays or infinite distributed delays. The idea is, under the help of Razumikhin technique, to reduce the study of IFDEs with infinite delays to the study of scalar impulsive differential equations (IDEs) in which the solutions are easy to deal with. Based on the comparison principle, we study the qualitative properties of IFDEs with infinite delays , which include stability, asymptotic stability, exponential stability, practical stability, boundedness, etc. It should be mentioned that the developed results in this paper can be applied to IFDEs with not only infinite delays but also persistent impulsive perturbations. Moreover, even for the special cases of non-impulsive effects or/and finite delays, the criteria prove to be simpler and less conservative than some existing results. Finally, two examples are given to illustrate the effectiveness and advantages of the proposed results.

Experimental studies of the MHD stability of non-circular Extrap Z-pinches

International Nuclear Information System (INIS)

Drake, J.R.

1985-01-01

Extrap Z-pinches, which can be sustained for many Alfven times, can be characterized as non-circular Z-pinch discharges bounded by a magnetic separatrix acting somewhat like a limiter. The magnetic separatrix is produced when a vacuum magnetic field, generated by currents in external conductors, combines with the self-magnetic field produced by the discharge current. The separatrix deforms the pinch cross-section and affects the equilibrium at the pinch boundary; both effects improve stability. Experiments have been performed which indicate that both effects are necessary for the successful generation of sustained Extrap discharges. In one experiment, the importance of the non-circularity of the cross-section was investigated. The deformation provided by the vacuum field can provide regions in the discharge where field lines have good curvature, which improves the stability of the configuration against internal modes. In configurations apparently lacking good curvature, discharges could not be sustained. In a second experiment, the dependence of the amplitude of global kink instabilities on the discharge current density profile were studied. The behaviour of the modes was consistent with that which would be expected for surface current-driven modes. (orig.)

Experimental studies of the MHD stability of non-circular extrap Z-pinches

International Nuclear Information System (INIS)

Drake, J.R.

1984-12-01

Extrap Z-pinches, which can be sustained for many Alfven times, can be characterized as non-circular Z-pinch discharges bounded by a magnetic separatrix acting somewhat like a limiter. The magnetic separatrix is produced when a vacuum magnetic field, generated by currents in external conductors, combines with the self-magnetic field produced by the discharge current. The separatrix deforms the pinch cross-section and affects the equilibrium at the pinch boundary; both effects improve stability. Experiments have been performed which indicate that both effects are necessary for the successful generation of sustained Extrap discharges. In one experiment, the importance of the non-circularity of the cross-section was investigated. The deformation provided by the vacuum field can provide regions in the discharge where field lines have good curvature, which improves the stability of the configuration against internal modes. In configurations apparently lacking good curvature, discharges could not be sustained. In a second experiment, the dependence of the amplitude of global kink instabilities on the discharge current density profile were studied. The behaviour of the modes was consistent with that which would be expected for surface current-driven modes. (Author)

Price elasticity of demand of non-cigarette tobacco products: a systematic review and meta-analysis.

Science.gov (United States)

Jawad, Mohammed; Lee, John Tayu; Glantz, Stanton; Millett, Christopher

2018-01-23

To systematically review the price elasticity of demand of non-cigarette tobacco products. Medline, Embase, EconLit and the Web of Science without language or time restrictions. Two reviewers screened title and abstracts, then full texts, independently and in duplicate. We based eligibility criteria on study design (interventional or observational), population (individuals or communities without geographic restrictions), intervention (price change) and outcome (change in demand). We abstracted data on study features, outcome measures, statistical approach, and single best own- and cross-price elasticity estimates with respect to cigarettes. We conducted a random effects meta-analysis for estimates of similar product, outcome and country income level. For other studies we reported median elasticities by product and country income level. We analysed 36 studies from 15 countries yielding 125 elasticity estimates. A 10% price increase would reduce demand by: 8.3% for cigars (95% CI 2.9 to 13.8), 6.4% for roll your owns (95% CI 4.3 to 8.4), 5.7% for bidis (95% CI 4.3 to 7.1) and 2.1% for smokeless tobacco (95% CI -0.6 to 4.8). Median price elasticities for all ten products were also negative. Results from few studies that examined cross-price elasticity suggested a positive substitution effect between cigarette and non-cigarette tobacco products. There is sufficient evidence in support of the effectiveness of price increases to reduce consumption of non-cigarette tobacco products as it is for cigarettes. Positive substitutability between cigarette and non-cigarette tobacco products suggest that tax and price increases need to be simultaneous and comparable across all tobacco products. © Article author(s) (or their employer(s) unless otherwise stated in the text of the article) 2018. All rights reserved. No commercial use is permitted unless otherwise expressly granted.

Wave propagation in elastic medium with heterogeneous quadratic nonlinearity

International Nuclear Information System (INIS)

Tang Guangxin; Jacobs, Laurence J.; Qu Jianmin

2011-01-01

This paper studies the one-dimensional wave propagation in an elastic medium with spatially non-uniform quadratic nonlinearity. Two problems are solved analytically. One is for a time-harmonic wave propagating in a half-space where the displacement is prescribed on the surface of the half-space. It is found that spatial non-uniformity of the material nonlinearity causes backscattering of the second order harmonic, which when combined with the forward propagating waves generates a standing wave in steady-state wave motion. The second problem solved is the reflection from and transmission through a layer of finite thickness embedded in an otherwise linearly elastic medium of infinite extent, where it is assumed that the layer has a spatially non-uniform quadratic nonlinearity. The results show that the transmission coefficient for the second order harmonic is proportional to the spatial average of the nonlinearity across the thickness of the layer, independent of the spatial distribution of the nonlinearity. On the other hand, the coefficient of reflection is proportional to a weighted average of the nonlinearity across the layer thickness. The weight function in this weighted average is related to the propagating phase, thus making the coefficient of reflection dependent on the spatial distribution of the nonlinearity. Finally, the paper concludes with some discussions on how to use the reflected and transmitted second harmonic waves to evaluate the variance and autocorrelation length of nonlinear parameter β when the nonlinearity distribution in the layer is a stochastic process.

Free vibration analysis of multi directional functionally graded circular and annular plates

Energy Technology Data Exchange (ETDEWEB)

Kermani, Iman Davoodi; Ghayour, Mostafa; Mirdamadi, Hamid Reza [Isfahan Univ. of Technology, Isfahan (Iran, Islamic Republic of)

2012-11-15

This paper addresses the free vibration of multi directional functionally graded circular and annular plates using a semianalytical/numerical method, called state space based differential quadrature method. Three-dimensional elasticity equations are derived for multi directional functionally graded plates and a solution is given by the semi-analytical/numerical method. This method gives an analytical solution along the thickness direction, using a state space method and a numerical solution using differential quadrature method. Some numerical examples are presented to show the accuracy and convergence of the method. The most of simulations of the present study have been validated by the existing literature. The non dimensional frequencies and corresponding displacements mode shapes are obtained. Then the influences of thickness ratio and graded indexes are demonstrated on the non dimensional natural frequencies.

Elastic stability of thick auxetic plates

International Nuclear Information System (INIS)

Lim, Teik-Cheng

2014-01-01

Auxetic materials and structures exhibit a negative Poisson’s ratio while thick plates encounter shear deformation, which is not accounted for in classical plate theory. This paper investigates the effect of a negative Poisson’s ratio on thick plates that are subjected to buckling loads, taking into consideration the shear deformation using Mindlin plate theory. Using a highly accurate shear correction factor that allows for the effect of Poisson’s ratio, the elastic stability of circular and square plates are evaluated in terms of dimensionless parameters, namely the Mindlin-to-Kirchhoff critical buckling load ratio and Mindlin critical buckling load factors. Results for thick square plates reveal that both parameters increase as the Poisson’s ratio becomes more negative. In the case of thick circular plates, the Mindlin-to-Kirchhoff critical buckling load ratios and the Mindlin critical buckling load factors increase and decrease, respectively, as the Poisson’s ratio becomes more negative. The results obtained herein show that thick auxetic plates behave as thin conventional plates, and therefore suggest that the classical plate theory can be used to evaluate the elastic stability of thick plates if the Poisson’s ratio of the plate material is sufficiently negative. The results also suggest that materials with highly negative Poisson’s ratios are recommended for square plates, but not circular plates, that are subjected to buckling loads. (paper)

Non-linear buckling of an FGM truncated conical shell surrounded by an elastic medium

International Nuclear Information System (INIS)

Sofiyev, A.H.; Kuruoglu, N.

2013-01-01

In this paper, the non-linear buckling of the truncated conical shell made of functionally graded materials (FGMs) surrounded by an elastic medium has been studied using the large deformation theory with von Karman–Donnell-type of kinematic non-linearity. A two-parameter foundation model (Pasternak-type) is used to describe the shell–foundation interaction. The FGM properties are assumed to vary continuously through the thickness direction. The fundamental relations, the modified Donnell type non-linear stability and compatibility equations of the FGM truncated conical shell resting on the Pasternak-type elastic foundation are derived. By using the Superposition and Galerkin methods, the non-linear stability equations for the FGM truncated conical shell is solved. Finally, influences of variations of Winkler foundation stiffness and shear subgrade modulus of the foundation, compositional profiles and shell characteristics on the dimensionless critical non-linear axial load are investigated. The present results are compared with the available data for a special case. -- Highlights: • Nonlinear buckling of FGM conical shell surrounded by elastic medium is studied. • Pasternak foundation model is used to describe the shell–foundation interaction. • Nonlinear basic equations are derived. • Problem is solved by using Superposition and Galerkin methods. • Influences of various parameters on the nonlinear critical load are investigated

Gas pressure in bubble attached to tube circular outlet

OpenAIRE

Salonen, A; Gay, Cyprien; Maestro, A; Drenckhan, W; Rio, Emmanuelle

2016-01-01

In the present Supplementary notes to our work ``Arresting bubble coarsening: A two-bubble experiment to investigate grain growth in presence of surface elasticity'' (accepted in EPL), we derive the expression of the gas pressure inside a bubble located above and attached to the circular outlet of a vertical tube.

A thermodynamic analysis of non-equilibrium heat conduction in a semi-infinite medium subjected to a step change in temperature

Energy Technology Data Exchange (ETDEWEB)

Hussain, A.K.; Hussain, T.A.; Shahad, Haroun A.K. [Babylon Univ., Dept. of Mechanical Engineering, Babylon (Iraq)

2003-05-01

The problem of non-equilibrium heat conduction in a semi-infinite medium subjected to a step change in temperature is analyzed thermodynamically using the extended irreversible thermodynamic approach. The results show clearly the wave nature of the dimensionless temperature distribution, Stanton number and the dimensionless entropy change profiles. The non-equilibrium profiles approach the equilibrium profiles as the speed of wave propagation is increased. The results also show that the non-equilibrium temperature is higher than the equilibrium temperature but the difference decreases as the wave propagation speed increases. (Author)

Infinite matrices and sequence spaces

CERN Document Server

Cooke, Richard G

2014-01-01

This clear and correct summation of basic results from a specialized field focuses on the behavior of infinite matrices in general, rather than on properties of special matrices. Three introductory chapters guide students to the manipulation of infinite matrices, covering definitions and preliminary ideas, reciprocals of infinite matrices, and linear equations involving infinite matrices.From the fourth chapter onward, the author treats the application of infinite matrices to the summability of divergent sequences and series from various points of view. Topics include consistency, mutual consi

A numerical investigation of laminar forced convection in a solar collector with non-circular duct

Directory of Open Access Journals (Sweden)

Teleszewski Tomasz Janusz

2017-01-01

Full Text Available This paper presents a two-dimensional numerical study to investigate laminar flow in a flat plate solar collector with non-circular duct (regular polygonal, elliptical, and Cassini oval shape featuring forced convection with constant axial wall heat flux and constant peripheral wall temperature (H1 condition. Applying the velocity profile obtained for the duct laminar flow, the energy equation was solved exactly for the constant wall heat flux using the Boundary Element Method (BEM. Poiseuille and Nusselt numbers were obtained for flows having a different number of geometrical factors. The results are presented and discussed in the form of tables and graphs. The area goodness factor and volume goodness factor are calculated. The predicted correlations for Poiseuille and Nusselt numbers may be a very useful resource for the design and optimization of solar collectors with non-circular ducts.

A numerical investigation of laminar forced convection in a solar collector with non-circular duct

Science.gov (United States)

Janusz Teleszewski, Tomasz

2017-11-01

This paper presents a two-dimensional numerical study to investigate laminar flow in a flat plate solar collector with non-circular duct (regular polygonal, elliptical, and Cassini oval shape) featuring forced convection with constant axial wall heat flux and constant peripheral wall temperature (H1 condition). Applying the velocity profile obtained for the duct laminar flow, the energy equation was solved exactly for the constant wall heat flux using the Boundary Element Method (BEM). Poiseuille and Nusselt numbers were obtained for flows having a different number of geometrical factors. The results are presented and discussed in the form of tables and graphs. The area goodness factor and volume goodness factor are calculated. The predicted correlations for Poiseuille and Nusselt numbers may be a very useful resource for the design and optimization of solar collectors with non-circular ducts.

Elastic interaction of partially debonded circular inclusions. II. Application to fibrous composite

DEFF Research Database (Denmark)

Kushch, V.I.; Shmegera, S.V.; Mishnaevsky, Leon

2011-01-01

have been solved to check an accuracy and numerical efficiency of the method. An effect of interface crack density on the effective elastic moduli of periodic and random structure FRC with interface damage has been evaluated. The developed approach provides a detailed analysis of the progressive...... debonding phenomenon including the interface cracks cluster formation, overall stiffness reduction and damage-induced anisotropy of the effective elastic moduli of composite....

Parity Non-Conservation in Proton-Proton Elastic Scattering

International Nuclear Information System (INIS)

Brown, V.R.; B.F. Gibson; J.A. Carlson; R. Schiavilla

2002-01-01

The parity non-conserving longitudinal asymmetry in proton-proton (pp) elastic scattering is calculated in the lab-energy range 0-350 MeV using contemporary, realistic strong-interaction potentials combined with a weak-interaction potential comprised of rho- and omega-meson exchanges as exemplified by the DDH model. Values for the rho- and omega-meson coupling constants, h rho rho rho and h rho rho omega , are determined from comparison with the measured asymmetries at 13.6 MeV, 45 MeV, and 221 MeV

QUANTITATIVE NON-DESTRUCTIVE EVALUATION (QNDE) OF THE ELASTIC MODULI OF POROUS TIAL ALLOYS

International Nuclear Information System (INIS)

Yeheskel, O.

2008-01-01

The elastic moduli of γ-TiA1 were studied in porous samples consolidated by various techniques e.g. cold isostatic pressing (CIP), pressure-less sintering, or hot isostatic pressing (HIP). Porosity linearly affects the dynamic elastic moduli of samples. The results indicate that the sound wave velocities and the elastic moduli affected by the processing route and depend not only on the attained density but also on the consolidation temperature. In this paper we show that there is linear correlation between the shear and the longitudinal sound velocities in porous TiA1. This opens the way to use a single sound velocity as a tool for quantitative non-destructive evaluation (QNDE) of porous TiA1 alloys. Here we demonstrate the applicability of an equation derived from the elastic theory and used previously for porous cubic metals

Longitudinally Vibrating Elastic Rods with Locally and Non-Locally Reacting Viscous Dampers

Directory of Open Access Journals (Sweden)

Şefaatdin Yüksel

2005-01-01

Full Text Available Eigencharacteristics of a longitudinally vibrating elastic rod with locally and non-locally reacting damping are analyzed. The rod is considered as a continuous system and complex eigenfrequencies are determined as solution of a characteristic equation. The variation of the damping ratios with respect to damper locations and damping coefficients for the first four eigenfrequencies are obtained. It is shown that at any mode of locally or non-locally damped elastic rod, the variation of damping ratio with damper location is linearly proportional to absolute value of the mode shape of undamped system. It is seen that the increasing damping coefficient does not always increase the damping ratio and there are optimal values for the damping ratio. Optimal values for external damping coefficients of viscous dampers and locations of the dampers are presented.

Non-linear theory of elasticity

CERN Document Server

Lurie, AI

2012-01-01

This book examines in detail the Theory of Elasticity which is a branch of the mechanics of a deformable solid. Special emphasis is placed on the investigation of the process of deformation within the framework of the generally accepted model of a medium which, in this case, is an elastic body. A comprehensive list of Appendices is included providing a wealth of references for more in depth coverage. The work will provide both a stimulus for future research in this field as well as useful reference material for many years to come.

Finite-thickness effects on the Rayleigh-Taylor instability in accelerated elastic solids

Science.gov (United States)

Piriz, S. A.; Piriz, A. R.; Tahir, N. A.

2017-05-01

A physical model has been developed for the linear Rayleigh-Taylor instability of a finite-thickness elastic slab laying on top of a semi-infinite ideal fluid. The model includes the nonideal effects of elasticity as boundary conditions at the top and bottom interfaces of the slab and also takes into account the finite transit time of the elastic waves across the slab thickness. For Atwood number AT=1 , the asymptotic growth rate is found to be in excellent agreement with the exact solution [Plohr and Sharp, Z. Angew. Math. Mech. 49, 786 (1998), 10.1007/s000330050121], and a physical explanation is given for the reduction of the stabilizing effectiveness of the elasticity for the thinner slabs. The feedthrough factor is also calculated.

Guide for the 2 infinities - the infinitely big and the infinitely small

International Nuclear Information System (INIS)

Armengaud, E.; Arnaud, N.; Aubourg, E.; Bassler, U.; Binetruy, P.; Bouquet, A.; Boutigny, D.; Brun, P.; Chassande-Mottin, E.; Chardin, G.; Coustenis, A.; Descotes-Genon, S.; Dole, H.; Drouart, A.; Elbaz, D.; Ferrando, Ph.; Glicenstein, J.F.; Giraud-Heraud, Y.; Halloin, H.; Kerhoas-Cavata, S.; De Kerret, H.; Klein, E.; Lachieze-Rey, M.; Lagage, P.O.; Langer, M.; Lebrun, F.; Lequeux, J.; Meheut, H.; Moniez, M.; Palanque-Delabrouille, N.; Paul, J.; Piquemal, F.; Polci, F.; Proust, D.; Richard, F.; Robert, J.L.; Rosnet, Ph.; Roudeau, P.; Royole-Degieux, P.; Sacquin, Y.; Serreau, J.; Shifrin, G.; Sida, J.L.; Smith, D.; Sordini, V.; Spiro, M.; Stolarczyk, Th.; Suomijdrvi, T.; Tagger, M.; Vangioni, E.; Vauclair, S.; Vial, J.C.; Viaud, B.; Vignaud, D.

2010-01-01

This book is to be read from both ends: one is dedicated to the path towards the infinitely big and the other to the infinitely small. Each path is made of a series of various subject entries illustrating important concepts or achievements in the quest for the understanding of the concerned infinity. For instance the part concerning the infinitely small includes entries like: quarks, Higgs bosons, radiation detection, Chooz neutrinos... while the part for the infinitely big includes: the universe, cosmic radiations, black matter, antimatter... and a series of experiments such as HESS, INTEGRAL, ANTARES, JWST, LOFAR, Planck, LSST, SOHO, Virgo, VLT, or XMM-Newton. This popularization work includes also an important glossary that explains scientific terms used in the entries. (A.C.)

A hierarchy of high-order theories for modes in an elastic layer

DEFF Research Database (Denmark)

Sorokin, Sergey V.; Chapman, C. John

2015-01-01

A hierarchy of high-order theories for symmetric and skew-symmetric modes in an infinitely long elastic layer of the constant thickness is derived. For each member of the hierarchy, boundary conditions for layers of the finite length are formulated. The forcing problems at several approximation...

Directional anisotropy, finite size effect and elastic properties of hexagonal boron nitride

International Nuclear Information System (INIS)

Thomas, Siby; Ajith, K M; Valsakumar, M C

2016-01-01

Classical molecular dynamics simulations have been performed to analyze the elastic and mechanical properties of two-dimensional (2D) hexagonal boron nitride (h-BN) using a Tersoff-type interatomic empirical potential. We present a systematic study of h-BN for various system sizes. Young’s modulus and Poisson’s ratio are found to be anisotropic for finite sheets whereas they are isotropic for the infinite sheet. Both of them increase with system size in accordance with a power law. It is concluded from the computed values of elastic constants that h-BN sheets, finite or infinite, satisfy Born’s criterion for mechanical stability. Due to the the strong in-plane sp 2 bonds and the small mass of boron and nitrogen atoms, h-BN possesses high longitudinal and shear velocities. The variation of bending rigidity with system size is calculated using the Foppl–von Karman approach by coupling the in-plane bending and out-of-plane stretching modes of the 2D h-BN. (paper)

Euclidean null controllability of nonlinear infinite delay systems with ...

African Journals Online (AJOL)

Sufficient conditions for the Euclidean null controllability of non-linear delay systems with time varying multiple delays in the control and implicit derivative are derived. If the uncontrolled system is uniformly asymptotically stable and if the control system is controllable, then the non-linear infinite delay system is Euclidean null ...

Pipeline robots with elastic elements

Directory of Open Access Journals (Sweden)

A. Matuliauskas

2002-10-01

Full Text Available In the article constructions of the pipeline robots with elastic elements are reviewed and the scheme of new original construction is presented. The mathematical models of a robot with one-dimensional vibration exciter with two degrees of freedom were developed and the equations of movement were formed and written. The mathematical model of the pipeline robot with circular elements is formed and its motion equations are presented.

BIRTH: a beam deposition code for non-circular tokamak plasmas

International Nuclear Information System (INIS)

Otsuka, Michio; Nagami, Masayuki; Matsuda, Toshiaki

1982-09-01

A new beam deposition code has been developed which is capable of calculating fast ion deposition profiles including the orbit correction. The code incorporates any injection geometry and a non-circular cross section plasma with a variable elongation and an outward shift of the magnetic flux surface. Typical cpu time on a DEC-10 computer is 10 - 20 seconds and 5 - 10 seconds with and without the orbit correction, respectively. This is shorter by an order of magnitude than that of other codes, e.g., Monte Carlo codes. The power deposition profile calculated by this code is in good agreement with that calculated by a Monte Carlo code. (author)

Finite Thin Cover on an Orthotropic Elastic Half Plane

Directory of Open Access Journals (Sweden)

Federico Oyedeji Falope

2016-01-01

Full Text Available The present work deals with the mechanical behaviour of thin films bonded to a homogeneous elastic orthotropic half plane under plain strain condition and infinitesimal strain. Both the film and semi-infinite substrate display linear elastic orthotropic behaviour. By assuming perfect adhesion between film and half plane together with membrane behaviour of the film, the compatibility condition between the coating and substrate leads to a singular integral equation with Cauchy kernel. Such an equation is straightforwardly solved by expanding the unknown interfacial stress in series of Chebyshev polynomials displaying square-root singularity at the film edges. This approach allows handling the singular behaviour of the shear stress and, in turn, reducing the problem to a linear algebraic system of infinite terms. Results are found for two loading cases, with particular reference to concentrated axial forces acting at the edges of the film. The corresponding mode II stress intensity factor has been assessed, thus providing the stress concentrations at both ends of the covering. Possible applications of the results here obtained range from MEMS, NEMS, and solar Silicon cell for energy harvesting to welded joint and building foundation.

The heterogeneous gas with singular interaction: generalized circular law and heterogeneous renormalized energy

International Nuclear Information System (INIS)

Molino, Luis Carlos García del; Pakdaman, Khashayar; Touboul, Jonathan

2015-01-01

We introduce and analyze d-dimensional Coulomb gases with random charge distribution and general external confining potential. We show that these gases satisfy a large-deviation principle. The analysis of the minima of the rate function (which is the leading term of the energy) reveals that, at equilibrium, the particle distribution is a generalized circular law (i.e. with spherical support but not necessarily uniform distribution). In the classical electrostatic external potential, there are infinitely many minimizers of the rate function. The most likely macroscopic configuration is a disordered distribution in which particles are uniformly distributed (for d = 2, the circular law), and charges are independent of the positions of the particles. General charge-dependent confining potentials unfold this degenerate situation: in contrast, the particle density is not uniform, and particles spontaneously organize according to their charge. In this picture the classical electrostatic potential appears as a transition at which order is lost. Sub-leading terms of the energy are derived: we show that these are related to an operator, generalizing the Coulomb renormalized energy, which incorporates the heterogeneous nature of the charges. This heterogeneous renormalized energy informs us about the microscopic arrangements of the particles, which are non-standard, strongly dependent on the charges, and include progressive and irregular lattices. (paper)

Infinite Shannon entropy

International Nuclear Information System (INIS)

Baccetti, Valentina; Visser, Matt

2013-01-01

Even if a probability distribution is properly normalizable, its associated Shannon (or von Neumann) entropy can easily be infinite. We carefully analyze conditions under which this phenomenon can occur. Roughly speaking, this happens when arbitrarily small amounts of probability are dispersed into an infinite number of states; we shall quantify this observation and make it precise. We develop several particularly simple, elementary, and useful bounds, and also provide some asymptotic estimates, leading to necessary and sufficient conditions for the occurrence of infinite Shannon entropy. We go to some effort to keep technical computations as simple and conceptually clear as possible. In particular, we shall see that large entropies cannot be localized in state space; large entropies can only be supported on an exponentially large number of states. We are for the time being interested in single-channel Shannon entropy in the information theoretic sense, not entropy in a stochastic field theory or quantum field theory defined over some configuration space, on the grounds that this simple problem is a necessary precursor to understanding infinite entropy in a field theoretic context. (paper)

Broadband computation of the scattering coefficients of infinite arbitrary cylinders.

Science.gov (United States)

Blanchard, Cédric; Guizal, Brahim; Felbacq, Didier

2012-07-01

We employ a time-domain method to compute the near field on a contour enclosing infinitely long cylinders of arbitrary cross section and constitution. We therefore recover the cylindrical Hankel coefficients of the expansion of the field outside the circumscribed circle of the structure. The recovered coefficients enable the wideband analysis of complex systems, e.g., the determination of the radar cross section becomes straightforward. The prescription for constructing such a numerical tool is provided in great detail. The method is validated by computing the scattering coefficients for a homogeneous circular cylinder illuminated by a plane wave, a problem for which an analytical solution exists. Finally, some radiation properties of an optical antenna are examined by employing the proposed technique.

Interaction between infinitely many dislocations and a semi-infinite crack in one-dimensional hexagonal quasicrystal

International Nuclear Information System (INIS)

Liu Guan-Ting; Yang Li-Ying

2017-01-01

By means of analytic function theory, the problems of interaction between infinitely many parallel dislocations and a semi-infinite crack in one-dimensional hexagonal quasicrystal are studied. The analytic solutions of stress fields of the interaction between infinitely many parallel dislocations and a semi-infinite crack in one-dimensional hexagonal quasicrystal are obtained. They indicate that the stress concentration occurs at the dislocation source and the tip of the crack, and the value of the stress increases with the number of the dislocations increasing. These results are the development of interaction among the finitely many defects of quasicrystals, which possesses an important reference value for studying the interaction problems of infinitely many defects in fracture mechanics of quasicrystal. (paper)

Cylindrical magnetization model for glass-coated microwires with circular anisotropy: Statics

International Nuclear Information System (INIS)

Torrejon, J.; Thiaville, A.; Adenot-Engelvin, A.L.; Vazquez, M.; Acher, O.

2011-01-01

The static magnetization profile of glass-coated microwires with effective circular anisotropy is investigated using micromagnetics. In this family of microwires, the ferromagnetic nucleus with an amorphous character presents a magnetic structure composed of an inner region with axial domains and an outer region with circular domains, due to magnetoelastic anisotropy. A one-dimensional micromagnetic model is developed, taking into account both the exchange and magnetoelastic anisotropy energies, and solved quasi analytically. The total energy, magnetization profiles and magnetization curves are investigated as a function of radius and anisotropy constant of the nucleus. This work represents a fundamental study of the magnetization process in these amorphous microwires and provides guidelines for the production of microwires with tailored magnetic properties. En passant, the nucleation problem in an infinite cylinder, introduced by W.F. Brown, is revisited. - Research highlights: → Magnetic microwires with circular anisotropy are studied by micromagnetic model. → The ratio R/Δ is a fundamental quantity to determine the magnetic structure. → Reduction of diameter and anisotropy favours the growth of axial core.

Weakly infinite-dimensional spaces

International Nuclear Information System (INIS)

Fedorchuk, Vitalii V

2007-01-01

In this survey article two new classes of spaces are considered: m-C-spaces and w-m-C-spaces, m=2,3,...,∞. They are intermediate between the class of weakly infinite-dimensional spaces in the Alexandroff sense and the class of C-spaces. The classes of 2-C-spaces and w-2-C-spaces coincide with the class of weakly infinite-dimensional spaces, while the compact ∞-C-spaces are exactly the C-compact spaces of Haver. The main results of the theory of weakly infinite-dimensional spaces, including classification via transfinite Lebesgue dimensions and Luzin-Sierpinsky indices, extend to these new classes of spaces. Weak m-C-spaces are characterised by means of essential maps to Henderson's m-compacta. The existence of hereditarily m-strongly infinite-dimensional spaces is proved.

Optimization of elastic elements of a damping devices for cylindrical hinges in crane-manipulating installations of mobile machines

Directory of Open Access Journals (Sweden)

Lagerev I.A.

2016-03-01

Full Text Available The article considers the problems of designing an original damping devices worn for cylindrical hinges in crane-manipulating installations of mobile machines. These devices can significantly reduce the additional impact load on a steel structure manipulators due to the presence of increased gaps in the hinges. Formulated the general formulation of nonlinear constrained optimization of the sizes of the elastic elements of the damping devices. Considered a promising design variants of elastic elements. For circular and arc elastic elements with circular and rectangular cross-section for-mulated the problems of optimal design including criterion functions and systems of geometric, technological, stiffness and strength penalty constraints. Analysis of the impact of various operating and design parameters on the results of optimal design of elastic elements was performed. Were set to the recommended the use of the constructive types of elastic elements to generate the required stiffness of the damper devices.

Electron temperature gradient mode instability and stationary vortices with elliptic and circular boundary conditions in non-Maxwellian plasmas

Energy Technology Data Exchange (ETDEWEB)

Haque, Q. [Theoretical Physics Division, PINSTECH, P.O. Nilore, Islamabad (Pakistan); Zakir, U. [Department of Physics, University of Peshawar, Khyber Pakhtun Khwa 25000 (Pakistan); Department of Physics, University of Malakand, Khyber Pakhtun Khwa 18800 (Pakistan); Qamar, A. [Department of Physics, University of Peshawar, Khyber Pakhtun Khwa 25000 (Pakistan)

2015-12-15

Linear and nonlinear dynamics of electron temperature gradient mode along with parallel electron dynamics is investigated by considering hydrodynamic electrons and non-Maxwellian ions. It is noticed that the growth rate of η{sub e}-mode driven linear instability decreases by increasing the value of spectral index and increases by reducing the ion/electron temperature ratio along the magnetic field lines. The eigen mode dispersion relation is also found in the ballooning mode limit. Stationary solutions in the form of dipolar vortices are obtained for both circular and elliptic boundary conditions. It is shown that the dynamics of both circular and elliptic vortices changes with the inclusion of inhomogeneity and non-Maxwellian effects.

Electron temperature gradient mode instability and stationary vortices with elliptic and circular boundary conditions in non-Maxwellian plasmas

Science.gov (United States)

Haque, Q.; Zakir, U.; Qamar, A.

2015-12-01

Linear and nonlinear dynamics of electron temperature gradient mode along with parallel electron dynamics is investigated by considering hydrodynamic electrons and non-Maxwellian ions. It is noticed that the growth rate of ηe-mode driven linear instability decreases by increasing the value of spectral index and increases by reducing the ion/electron temperature ratio along the magnetic field lines. The eigen mode dispersion relation is also found in the ballooning mode limit. Stationary solutions in the form of dipolar vortices are obtained for both circular and elliptic boundary conditions. It is shown that the dynamics of both circular and elliptic vortices changes with the inclusion of inhomogeneity and non-Maxwellian effects.

Elastic interaction of partially debonded circular inclusions. I. Theoretical solution

DEFF Research Database (Denmark)

Kushch, V.I.; Shmegera, S.V.; Mishnaevsky, Leon

2010-01-01

and provides a simple and rapidly convergent iterative algorithm. The presented numerical data show an accuracy and numerical efficiency of the proposed method and discover the way and extent to which the elastic interaction between the partially debonded inclusions affects the local fields, stress intensity...... factors and the energy release rate at the interface crack tips....

Compact solitary waves in linearly elastic chains with non-smooth on-site potential

Energy Technology Data Exchange (ETDEWEB)

Gaeta, Giuseppe [Dipartimento di Matematica, Universita di Milano, Via Saldini 50, 20133 Milan (Italy); Gramchev, Todor [Dipartimento di Matematica e Informatica, Universita di Cagliari, Via Ospedale 72, 09124 Cagliari (Italy); Walcher, Sebastian [Lehrstuhl A Mathematik, RWTH Aachen, 52056 Aachen (Germany)

2007-04-27

It was recently observed by Saccomandi and Sgura that one-dimensional chains with nonlinear elastic interaction and regular on-site potential can support compact solitary waves, i.e. travelling solitary waves with strictly compact support. In this paper, we show that the same applies to chains with linear elastic interaction and an on-site potential which is continuous but non-smooth at minima. Some different features arise; in particular, the speed of compact solitary waves is not uniquely fixed by the equation. We also discuss several generalizations of our findings.

Concave pulse shaping of a circularly polarized laser pulse from non-uniform overdense plasmas

Energy Technology Data Exchange (ETDEWEB)

Hur, Min Sup [School of Natural Science, UNIST, BanYeon-Ri 100, Ulju-gun, Ulsan, 689-798 (Korea, Republic of); Kulagin, Victor V. [Sternberg Astronomical Institute, Moscow State University, Universitetsky prosp. 13, Moscow, 119992 (Russian Federation); Suk, Hyyong, E-mail: hysuk@gist.ac.kr [Department of Physics and Photon Science, GIST, 123 Cheomdan-gwangiro, Buk-gu, Gwangju, 500-712 (Korea, Republic of)

2015-03-20

Pulse shaping of circularly polarized laser pulses in nonuniform overdense plasmas are investigated numerically. Specifically we show by two-dimensional particle-in-cell simulations the generation of a concave pulse front of a circularly polarized, a few tens of petawatt laser pulse from a density-tapered, overdense plasma slab. The concept used for the transverse-directional shaping is the differential transmittance depending on the plasma density, and the laser intensity. For suitable selection of the slab parameters for the concave pulse shaping, we studied numerically the pulse transmittance, which can be used for further parameter design of the pulse shaping. The concavely shaped circularly polarized pulse is expected to add more freedom in controlling the ion-beam characteristics in the RPDA regime. - Highlights: • Laser pulse shaping for a concave front by non-uniform overdense plasma was studied. • Particle-in-cell (PIC) simulations were used for the investigation. • A laser pulse can be shaped by a density-tapered overdense plasma. • The concave and sharp pulse front are useful in many laser–plasma applications. • They are important for ion acceleration, especially in the radiation pressure dominant regime.

Anticavitation and Differential Growth in Elastic Shells

KAUST Repository

Moulton, Derek E.

2010-07-22

Elastic anticavitation is the phenomenon of a void in an elastic solid collapsing on itself. Under the action of mechanical loading alone typical materials do not admit anticavitation. We study the possibility of anticavitation as a consequence of an imposed differential growth. Working in the geometry of a spherical shell, we seek radial growth functions which cause the shell to deform to a solid sphere. It is shown, surprisingly, that most material models do not admit full anticavitation, even when infinite growth or resorption is imposed at the inner surface of the shell. However, void collapse can occur in a limiting sense when radial and circumferential growth are properly balanced. Growth functions which diverge or vanish at a point arise naturally in a cumulative growth process. © 2010 Springer Science+Business Media B.V.

Non-axisymmetric flexural vibrations of free-edge circular silicon wafers

Energy Technology Data Exchange (ETDEWEB)

Dmitriev, A.V., E-mail: dmitriev@hbar.phys.msu.ru; Gritsenko, D.S.; Mitrofanov, V.P., E-mail: mitr@hbar.phys.msu.ru

2014-02-07

Non-axisymmetric flexural vibrations of circular silicon (111) wafers are investigated. The modes with azimuthal index 2⩽k⩽30 are electrostatically excited and monitored by a capacitive sensor. The splitting of the mode frequencies associated with imperfection of the wafer is observed. The measured loss factors for the modes with 6≲k≲26 are close to those calculated according to the thermoelastic damping theory, while clamping losses likely dominate for k≲6, and surface losses at the level of inverse Q-factor Q{sup −1}≈4×10{sup −6} prevail for the modes with large k. The modes demonstrate nonlinear behavior of mainly geometrical origin at large amplitudes.

Analytic solutions of Oldroyd-B fluid with fractional derivatives in a circular duct that applies a constant couple

Directory of Open Access Journals (Sweden)

M.B. Riaz

2016-12-01

Full Text Available The aim of this article was to analyze the rotational flow of an Oldroyd-B fluid with fractional derivatives, induced by an infinite circular cylinder that applies a constant couple to the fluid. Such kind of problem in the settings of fractional derivatives has not been found in the literature. The solutions are based on an important remark regarding the governing equation for the non-trivial shear stress. The solutions that have been obtained satisfy all imposed initial and boundary conditions and can easily be reduced to the similar solutions corresponding to ordinary Oldroyd-B, fractional/ordinary Maxwell, fractional/ordinary second-grade, and Newtonian fluids performing the same motion. The obtained results are expressed in terms of Newtonian and non-Newtonian contributions. Finally, the influence of fractional parameters on the velocity, shear stress and a comparison between generalized and ordinary fluids is graphically underlined.

The tail of two models: Impact of circularity and biomass non-homogeneity on UV disinfection of wastewater flocs.

Science.gov (United States)

Azimi, Y; Liu, Y; Tan, T C; Allen, D G; Farnood, R R

2017-12-01

The effects of floc structural characteristics, i.e. shape and dense biomass distribution, were evaluated on ultraviolet (UV) disinfection resistance, represented by the tailing level of the UV dose response curve (DRC). Ellipsoid-shaped flocs of similar volume and different projected circularities were constructed in-silico and a mathematical model was developed to compare their UV DRC tailing levels (indicative of UV-resistance). It was found that floc shape can significantly influence tailing level, and rounder flocs (i.e. flocs with higher circularity) were more UV-resistant. This result was confirmed experimentally by obtaining UV DRCs of two 75-90 μm floc populations with different percentages (20% vs. 30%) of flocs with circularities higher than 0.5. The population enriched in less circular flocs (i.e. 20% flocs with circularities >0.5) had a lower tailing level (at least by 1-log) compared to the other population. The second model was developed to describe variations in UV disinfection kinetics observed in flocs with transverse vs. radial biomass non-homogeneity, indicative of biofilm-originated vs. suspended flocs. The varied-density hemispheres model and shell-core model were developed to simulate transverse and radial non-homogeneity, respectively. The UV DRCs were mathematically constructed and biofilm-originated flocs showed higher UV resistance compared to suspended flocs. The calculated UV DRCs agreed well with the experimental data collected from activated sludge and trickling filter flocs (no fitting parameters were used). These findings provide useful information in terms of designing/modifying upstream processes for reducing UV disinfection energy demand. Copyright © 2017 Elsevier Ltd. All rights reserved.

Consequences of elastic anisotropy in patterned substrate heteroepitaxy.

Science.gov (United States)

Dixit, Gopal Krishna; Ranganathan, Madhav

2018-06-13

The role of elastic anisotropy on quantum dot formation and evolution on a pre-patterned substrate is evaluated within the framework of a continuum model. We first extend the formulation for surface evolution to take elastic anisotropy into account. Using a small slope approximation, we derive the evolution equation and show how it can be numerically implemented up to linear and second order for stripe and egg-carton patterned substrates using an accurate and efficient procedure. The semi--infinite nature of the substrate is used to solve the elasticity problem subject to other boundary conditions at the free surface and at the film--substrate interface. The positioning of the quantum dots with respect to the peaks and valleys of the pattern is explained by a competition between the length scale of the pattern and the wavelength of the Asaro--Tiller--Grinfeld instability, which is also affected by the elastic anisotropy. The alignment of dots is affected by a competition between the elastic anisotropy of the film and the pattern orientation. A domain of pattern inversion, wherein the quantum dots form exclusively in the valleys of the patterns is identified as a function of the average film thickness and the elastic anisotropy, and the time--scale for this inversion as function of height is analyzed. © 2018 IOP Publishing Ltd.

Motility analysis of circularly swimming bull spermatozoa by quasi-elastic light scattering and cinematography.

Science.gov (United States)

Craig, T; Hallett, F R; Nickel, B

1982-04-01

The Rayleigh-Gans-Debye approximation is used to predict the electric field autocorrelation functions of light scattered from circularly swimming bull spermatozoa. Using parameters determined from cinematography and modeling the cells as coated ellipsoids of semiaxes a = 0.5 micrometers, b = 2.3 micrometers, and c = 9.0 micrometers, we were able to obtain model spectra that mimic the data exactly. A coat is found to be a necessary attribute of the particle. It is also clear that these model functions at 15 degrees may be represented by the relatively simple function used before by Hallett et al. (1978) to fit data from circularly swimming cells, thus giving some physical meaning to these functional shapes. Because of this agreement the half-widths of experimental functions can now be interpreted in terms of an oscillatory frequency for the movement of the circularly swimming cell. The cinematographic results show a trend to chaotic behavior as the temperature of the sample is increased, with concomitant decrease in overall efficiency. This is manifested by a decrease in oscillatory frequency and translational speed.

Extreme non-linear elasticity and transformation optics

DEFF Research Database (Denmark)

Gersborg, Allan Roulund; Sigmund, Ole

2010-01-01

realizations correspond to minimizers of elastic energy potentials for extreme values of the mechanical Poisson's ratio ν . For TE (Hz) polarized light an incompressible transformation ν = 1/2 is ideal and for TM (E z) polarized light one should use a compressible transformation with negative Poissons's ratio......Transformation optics is a powerful concept for designing novel optical components such as high transmission waveguides and cloaking devices. The selection of specific transformations is a non-unique problem. Here we reveal that transformations which allow for all dielectric and broadband optical...... ν = -1. For the TM polarization the mechanical analogy corresponds to a modified Liao functional known from the transformation optics literature. Finally, the analogy between ideal transformations and solid mechanical material models automates and broadens the concept of transformation optics...

The Modeling of Viscoelastic Circular Plates for Use as Waveguide Absorbers

Science.gov (United States)

1988-09-01

oncituoe Security Ciasstircation) X THE MODELING OF VISCOELASTIC CIRCULAR PLATES FOR USE AS WAVEGUIDE ABSORBERS C 12 PERSONAL AUTmO ?S) -Hettema...33mvU3dT’U Figure 67. Experimental Jmainiey Part ot the Driving Point Jmpedancs of a 6 in Radius Elastic Plate, With and Without aaker and Mount Conecon, In

Geometric method for stability of non-linear elastic thin shells

CERN Document Server

Ivanova, Jordanka

2002-01-01

PREFACE This book deals with the new developments and applications of the geometric method to the nonlinear stability problem for thin non-elastic shells. There are no other published books on this subject except the basic ones of A. V. Pogorelov (1966,1967,1986), where variational principles defined over isometric surfaces, are postulated, and applied mainly to static and dynamic problems of elastic isotropic thin shells. A. V. Pogorelov (Harkov, Ukraine) was the first to provide in his monographs the geometric construction of the deformed shell surface in a post-critical stage and deriving explicitely the asymptotic formulas for the upper and lower critical loads. In most cases, these formulas were presented in a closed analytical form, and confirmed by experimental data. The geometric method by Pogorelov is one of the most important analytical methods developed during the last century. Its power consists in its ability to provide a clear geometric picture of the postcritical form of a deformed shell surfac...

Forced in-plane vibration of a thick ring on a unilateral elastic foundation

Science.gov (United States)

Wang, Chunjian; Ayalew, Beshah; Rhyne, Timothy; Cron, Steve; Dailliez, Benoit

2016-10-01

Most existing studies of a deformable ring on elastic foundation rely on the assumption of a linear foundation. These assumptions are insufficient in cases where the foundation may have a unilateral stiffness that vanishes in compression or tension such as in non-pneumatic tires and bushing bearings. This paper analyzes the in-plane dynamics of such a thick ring on a unilateral elastic foundation, specifically, on a two-parameter unilateral elastic foundation, where the stiffness of the foundation is treated as linear in the circumferential direction but unilateral (i.e. collapsible or tensionless) in the radial direction. The thick ring is modeled as an orthotropic and extensible circular Timoshenko beam. An arbitrarily distributed time-varying in-plane force is considered as the excitation. The Equations of Motion are explicitly derived and a solution method is proposed that uses an implicit Newmark scheme for the time domain solution and an iterative compensation approach to determine the unilateral zone of the foundation at each time step. The dynamic axle force transmission is also analyzed. Illustrative forced vibration responses obtained from the proposed model and solution method are compared with those obtained from a finite element model.

Non-hydrostatic semi-elastic hybrid-coordinate SISL extension of HIRLAM. Part II: numerical testing

OpenAIRE

Rõõm, Rein; Männik, Aarne; Luhamaa, Andres; Zirk, Marko

2007-01-01

The semi-implicit semi-Lagrangian (SISL), two-time-level, non-hydrostatic numerical scheme, based on the non-hydrostatic, semi-elastic pressure-coordinate equations, is tested in model experiments with flow over given orography (elliptical hill, mountain ridge, system of successive ridges) in a rectangular domain with emphasis on the numerical accuracy and non-hydrostatic effect presentation capability. Comparison demonstrates good (in strong primary wave generation) to satisfactory (in weak ...

'PRIZE': A program for calculating collision probabilities in R-Z geometry

Energy Technology Data Exchange (ETDEWEB)

Pitcher, H.H.W. [General Reactor Physics Division, Atomic Energy Establishment, Winfrith, Dorchester, Dorset (United Kingdom)

1964-10-15

PRIZE is an IBM7090 program which computes collision probabilities for systems with axial symmetry and outputs them on cards in suitable format for the PIP1 program. Its method of working, data requirements, output, running time and accuracy are described. The program has been used to compute non-escape (self-collision) probabilities of finite circular cylinders, and a table is given by which non-escape probabilities of slabs, finite and infinite circular cylinders, infinite square cylinders, cubes, spheres and hemispheres may quickly be calculated to 1/2% or better. (author)

'PRIZE': A program for calculating collision probabilities in R-Z geometry

International Nuclear Information System (INIS)

Pitcher, H.H.W.

1964-10-01

PRIZE is an IBM7090 program which computes collision probabilities for systems with axial symmetry and outputs them on cards in suitable format for the PIP1 program. Its method of working, data requirements, output, running time and accuracy are described. The program has been used to compute non-escape (self-collision) probabilities of finite circular cylinders, and a table is given by which non-escape probabilities of slabs, finite and infinite circular cylinders, infinite square cylinders, cubes, spheres and hemispheres may quickly be calculated to 1/2% or better. (author)

Semi-infinite assignment and transportation games

NARCIS (Netherlands)

Timmer, Judith B.; Sánchez-Soriano, Joaqu´ın; Llorca, Navidad; Tijs, Stef; Goberna, Miguel A.; López, Marco A.

2001-01-01

Games corresponding to semi-infinite transportation and related assignment situations are studied. In a semi-infinite transportation situation, one aims at maximizing the profit from the transportation of a certain good from a finite number of suppliers to an infinite number of demanders. An

Elastic strain relaxation in interfacial dislocation patterns: II. From long- and short-range interactions to local reactions

Science.gov (United States)

Vattré, A.

2017-08-01

The long- and short-range interactions as well as planar reactions between two infinitely periodic sets of crossing dislocations are investigated using anisotropic elasticity theory in face- (fcc) and body- (bcc) centered cubic materials. Two preliminary cases are proposed to examine the substantial changes in the elastic stress states and the corresponding strain energies due to a slight rearrangement in the internal dislocation geometries and characters. In general, significant differences and discrepancies resulting from the considered cubic crystal structure and the approximation of isotropic elasticity are exhibited. In a third scenario, special attention is paid to connecting specific internal dislocation structures from the previous cases with non-equilibrium configurations predicted by the quantized Frank-Bilby equation for the (111) fcc and (110) bcc twist grain boundaries. The present solutions lead to the formation of energetically favorable dislocation junctions with non-randomly strain-relaxed configurations of lower energy. In particular, the local dislocation interactions and reactions form equilibrium hexagonal-shaped patterns with planar three-fold dislocation nodes without producing spurious far-field stresses.Numerical application results are presented from a selection of cubic metals including aluminum, copper, tantalum, and niobium. In contrast to the fcc materials, asymmetric dislocation nodes occur in the anisotropic bcc cases, within which the minimum-energy paths for predicting the fully strain-relaxed dislocation patterns depend on the Zener anisotropic factor with respect to unity. The associated changes in the dislocation structures as well as the removal of the elastic strain energy upon relaxations are quantified and also discussed.

Hadronic currents in the infinite momentum frame

International Nuclear Information System (INIS)

Toth, K.

1975-01-01

The problem of the transformation properties of hadronic currents in the infinite momentum frame (IMF) is investigated. A general method is proposed to deal with the problem which is based upon the concept of group contraction. The two-dimensional aspects of the IMF description are studied in detail, and the current matrix elements of a three-dimensional Poincare covariant theory are reduced to those of a two-dimensional one. It is explicitlyshown that the covariance group of the two-dimensional theory may either be a 'non-relativistic' (Galilei) group, or a 'relativistic' (Poincare) one depending on the value of a parameter reminiscent of the light velocity in the three-dimensional theory. The value of this parameter cannot be determined by kinematical argument. These results offer a natural generalization of models which assume Galilean symmetry in the infinite momentum frame

A piezoelectric-based infinite stiffness generation method for strain-type load sensors

International Nuclear Information System (INIS)

Zhang, Shuwen; Shao, Shubao; Xu, Minglong; Chen, Jie

2015-01-01

Under certain application conditions like nanoindentation technology and the mechanical property measurement of soft materials, the elastic deformation of strain-type load sensors affects their displacement measurement accuracy. In this work, a piezoelectric-based infinite stiffness generation method for strain-type load sensors that compensates for this elastic deformation is presented. The piezoelectric material-based deformation compensation method is proposed. An Hottinger Baldwin Messtechnik GmbH (HBM) Z30A/50N load sensor acts as the foundation of the method presented in this work. The piezoelectric stack is selected based on its size, maximum deformation value, blocking force and stiffness. Then, a clamping and fixing structure is designed to integrate the HBM sensor with the piezoelectric stack. The clamping and fixing structure, piezoelectric stack and HBM load sensor comprise the sensing part of the enhanced load sensor. The load-deformation curve and the voltage-deformation curve of the enhanced load sensor are then investigated experimentally. Because a hysteresis effect exists in the piezoelectric structure, the relationship between the control signal and the deformation value of the piezoelectric material is nonlinear. The hysteresis characteristic in a quasi-static condition is studied and fitted using a quadratic polynomial, and its coefficients are analyzed to enable control signal prediction. Applied arithmetic based on current theory and the fitted data is developed to predict the control signal. Finally, the experimental effects of the proposed method are presented. It is shown that when a quasi-static load is exerted on this enhanced strain-type load sensor, the deformation is reduced and the equivalent stiffness appears to be almost infinite. (paper)

Computational simulations of hydrogen circular migration in protonated acetylene induced by circularly polarized light

Energy Technology Data Exchange (ETDEWEB)

Shi, Xuetao; Li, Wen; Schlegel, H. Bernhard, E-mail: hbs@chem.wayne.edu [Department of Chemistry, Wayne State University, Detroit, Michigan 48202 (United States)

2016-08-28

The hydrogens in protonated acetylene are very mobile and can easily migrate around the C{sub 2} core by moving between classical and non-classical structures of the cation. The lowest energy structure is the T-shaped, non-classical cation with a hydrogen bridging the two carbons. Conversion to the classical H{sub 2}CCH{sup +} ion requires only 4 kcal/mol. The effect of circularly polarized light on the migration of hydrogens in oriented C{sub 2}H{sub 3}{sup +} has been simulated by Born-Oppenheimer molecular dynamics. Classical trajectory calculations were carried out with the M062X/6-311+G(3df,2pd) level of theory using linearly and circularly polarized 32 cycle 7 μm cosine squared pulses with peak intensity of 5.6 × 10{sup 13} W/cm{sup 2} and 3.15 × 10{sup 13} W/cm{sup 2}, respectively. These linearly and circularly polarized pulses transfer similar amounts of energy and total angular momentum to C{sub 2}H{sub 3}{sup +}. The average angular momentum vectors of the three hydrogens show opposite directions of rotation for right and left circularly polarized light, but no directional preference for linearly polarized light. This difference results in an appreciable amount of angular displacement of the three hydrogens relative to the C{sub 2} core for circularly polarized light, but only an insignificant amount for linearly polarized light. Over the course of the simulation with circularly polarized light, this corresponds to a propeller-like motion of the three hydrogens around the C{sub 2} core of protonated acetylene.

Flow and Displacement of Non-Newtonian Fluid(Power-Law Model) by Surface Tension and Gravity Force in Inclined Circular Tube

International Nuclear Information System (INIS)

Moh, Jeong Hah; Cho, Y. I.

2014-01-01

This paper presents the theoretical analysis of a flow driven by surface tension and gravity in an inclined circular tube. A governing equation is developed for describing the displacement of a non-Newtonian fluid(Power-law model) that continuously flows into a circular tube owing to surface tension, which represents a second-order, nonlinear, non-homogeneous, and ordinary differential form. It was found that quantitatively, the theoretical predictions of the governing equation were in excellent agreement with the solutions of the equation for horizontal tubes and the past experimental data. In addition, the predictions compared very well with the results of the force balance equation for steady

Why aortic elasticity differs among classical and non-classical mitral valve prolapsed?

Science.gov (United States)

Unlu, Murat; Demirkol, Sait; Aparci, Mustafa; Arslan, Zekeriya; Balta, Sevket; Dogan, Umuttan; Kilicarslan, Baris; Ozeke, Ozcan; Celik, Turgay; Iyisoy, Atila

2014-01-01

Mitral valve prolapse (MVP) is the most common valvular heart disease and characterized by the displacement of an abnormally thickened mitral valve leaflet into the left atrium during systole. There are two types of MVP, broadly classified as classic (thickness ≥5 mm) and non-classic (thickness elastic properties of the aorta in young male patients with classical and non-classical MVP. In the present study, 63 young adult males (mean age: 22.7 ± 4.2) were included. Patients were divided into classic MVP (n = 27) and non-classic MVP (n = 36) groups. Aortic strain, aortic distensibility and aortic stiffness index were calculated by using aortic diameters obtained by echocardiography and blood pressures measured by sphygmomanometer. There was no significant difference between the groups in terms of age, body mass index, left ventricular mass and ejection fraction. When comparing the MVP group it was found that aortic strain and aortic distensibility were increased (p = 0.0027, p = 0.016, respectively) whereas the aortic stiffness index was decreased (p = 0.06) in the classical MVP group. We concluded that the elastic properties of the aorta is increased in patients with classic MVP. Further large scale studies should be performed to understand of morphological and physiological properties of the aorta in patients with MVP.

The elasticity of Substitution in demand for Non tradable Goods in Latin America. Case Study: Argentina

OpenAIRE

Pablo Andres Neumeyer; Martín Gonzalez Rozada

2003-01-01

This objective of this paper is to estimate the elasticity of substitution in the demand for non-tradable goods relative to tradable goods in Argentina. This parameter plays a crucial role in the analysis of the macroeconomic equilibrium of a small open economy (Mendoza, Galindo and Izquierdo (2003)). Using two data sets we found estimates for this elasticity of, approximately, 0.40 and 0.48.

Circular polarization of gravitational waves from non-rotating supernova cores: a new probe into the pre-explosion hydrodynamics

Science.gov (United States)

Hayama, Kazuhiro; Kuroda, Takami; Kotake, Kei; Takiwaki, Tomoya

2018-06-01

We present an analysis of the circular polarization of gravitational waves (GWs) using results from three-dimensional (3D), general relativistic (GR) core-collapse simulations of a non-rotating 15 M⊙ star. For the signal detection, we perform a coherent network analysis taking into account the four interferometers of LIGO Hanford, LIGO Livingston, VIRGO, and KAGRA. We focus on the Stokes V parameter, which directly characterizes the asymmetry of the GW circular polarization. We find that the amplitude of the GW polarization becomes bigger for our 3D-GR model that exhibits strong activity of the standing accretion shock instability (SASI). Our results suggest that the SASI-induced accretion flows to the proto-neutron star (PNS) lead to a characteristic, low-frequency modulation (100-200 Hz) in both the waveform and the GW circular polarization. By estimating the signal-to-noise ratio of the GW polarization, we demonstrate that the detection horizon of the circular polarization extends by more than a factor of several times farther comparing to that of the GW amplitude. Our results suggest that the GW circular polarization, if detected, could provide a new probe into the pre-explosion hydrodynamics such as the SASI activity and the g-mode oscillation of the PNS.

Circular polarization of gravitational waves from non-rotating supernova cores: a new probe into the pre-explosion hydrodynamics

Science.gov (United States)

Hayama, Kazuhiro; Kuroda, Takami; Kotake, Kei; Takiwaki, Tomoya

2018-04-01

We present an analysis of the circular polarization of gravitational-waves (GWs) using results from three-dimensional (3D), general relativistic (GR) core-collapse simulations of a non-rotating 15M⊙ star. For the signal detection, we perform a coherent network analysis taking into account the four interferometers of LIGO Hanford, LIGO Livingston, VIRGO, and KAGRA. We focus on the Stokes V parameter, which directly characterizes the asymmetry of the GW circular polarization. We find that the amplitude of the GW polarization becomes bigger for our 3D-GR model that exhibits strong activity of the standing accretion shock instability (SASI). Our results suggest that the SASI-induced accretion flows to the proto-neutron star (PNS) lead to a characteristic, low-frequency modulation (100 ˜ 200 Hz) in both the waveform and the GW circular polarization. By estimating the signal-to-noise ratio of the GW polarization, we demonstrate that the detection horizon of the circular polarization extends by more than a factor of several times farther comparing to that of the GW amplitude. Our results suggest that the GW circular polarization, if detected, could provide a new probe into the pre-explosion hydrodynamics such as the SASI activity and the g-mode oscillation of the PNS.

On the mechanism of bandgap formation in locally resonant finite elastic metamaterials

Science.gov (United States)

Sugino, Christopher; Leadenham, Stephen; Ruzzene, Massimo; Erturk, Alper

2016-10-01

Elastic/acoustic metamaterials made from locally resonant arrays can exhibit bandgaps at wavelengths much longer than the lattice size for various applications spanning from low-frequency vibration/sound attenuation to wave guiding and filtering in mechanical and electromechanical devices. For an effective use of such locally resonant metamaterial concepts in finite structures, it is required to bridge the gap between the lattice dispersion characteristics and modal behavior of the host structure with its resonators. To this end, we develop a novel argument for bandgap formation in finite-length elastic metamaterial beams, relying on the modal analysis and the assumption of infinitely many resonators. We show that the dual problem to wave propagation through an infinite periodic beam is the modal analysis of a finite beam with an infinite number of resonators. A simple formula that depends only on the resonator natural frequency and total mass ratio is derived for placing the bandgap in a desired frequency range, yielding an analytical insight and a rule of thumb for design purposes. A method for understanding the importance of a resonator location and mass is discussed in the context of a Riemann sum approximation of an integral, and a method for determining the optimal number of resonators for a given set of boundary conditions and target frequency is introduced. The simulations of the theoretical framework are validated by experiments for bending vibrations of a locally resonant cantilever beam.

Quantum walks with infinite hitting times

International Nuclear Information System (INIS)

Krovi, Hari; Brun, Todd A.

2006-01-01

Hitting times are the average time it takes a walk to reach a given final vertex from a given starting vertex. The hitting time for a classical random walk on a connected graph will always be finite. We show that, by contrast, quantum walks can have infinite hitting times for some initial states. We seek criteria to determine if a given walk on a graph will have infinite hitting times, and find a sufficient condition, which for discrete time quantum walks is that the degeneracy of the evolution operator be greater than the degree of the graph. The set of initial states which give an infinite hitting time form a subspace. The phenomenon of infinite hitting times is in general a consequence of the symmetry of the graph and its automorphism group. Using the irreducible representations of the automorphism group, we derive conditions such that quantum walks defined on this graph must have infinite hitting times for some initial states. In the case of the discrete walk, if this condition is satisfied the walk will have infinite hitting times for any choice of a coin operator, and we give a class of graphs with infinite hitting times for any choice of coin. Hitting times are not very well defined for continuous time quantum walks, but we show that the idea of infinite hitting-time walks naturally extends to the continuous time case as well

Circular arc structures

KAUST Repository

Bo, Pengbo; Pottmann, Helmut; Kilian, Martin; Wang, Wen Ping; Wallner, Johannes

2011-01-01

and connecting elements as well as repetition of costly parts. This paper proposes so-called circular arc structures as a means to faithfully realize freeform designs without giving up smooth appearance. In contrast to non-smooth meshes with straight edges where

A mathematical model of the rail track presented as a bar on elastic and dissipative supports under the influence of moving loads

Directory of Open Access Journals (Sweden)

Darenskiy Alexander

2017-01-01

Full Text Available At present, the most common track model is the one in which rails are presented as bars of infinite length rested on continuous elastic foundation. However, some specialists consider the model to be rather ideal for railways in terms of track and the technical state of track. Calculation of track as a bar rested on numerous elastic supports with variable characteristics of stiffness under static loads has shown that application of methods of elastic foundation gives results understated by 17-24%. The study presents mathematic models of the vehicle/track dynamic system, and a design scheme of track presented as a bar on numerous elastic dissipative supports with non-linear characteristics, which is taken on the base of this system. The authors developed models and methods to define the reduced vertical stiffness of the track in the wheel/rail contact point, which considers rail elastic and geometric characteristics, stiffness of supports, distance between supports and distributed track mass. The value of stiffness is variable by time for each wheel at any time and various for the vehicle’s wheels. The mathematical model proposed has been implemented in Matlab software and will make it possible to conduct numerical research into the track/vehicle dynamics.

On infinite regular and chiral maps

OpenAIRE

Arredondo, John A.; Valdez, Camilo Ramírez y Ferrán

2015-01-01

We prove that infinite regular and chiral maps take place on surfaces with at most one end. Moreover, we prove that an infinite regular or chiral map on an orientable surface with genus can only be realized on the Loch Ness monster, that is, the topological surface of infinite genus with one end.

78 FR 41424 - Audits of States, Local Governments, and Non-Profit Organizations; OMB Circular A-133 Compliance...

Science.gov (United States)

2013-07-10

... OFFICE OF MANAGEMENT AND BUDGET Audits of States, Local Governments, and Non-Profit Organizations... Management and Budget. ACTION: Notice of availability of the 2013 OMB Circular A-133 Compliance Supplement...--National Science and Mathematics Access to Retain Talent (SMART) Grants (SMART Grants) CFDA 84.390...

Two-craft Coulomb formation study about circular orbits and libration points

Science.gov (United States)

Inampudi, Ravi Kishore

This dissertation investigates the dynamics and control of a two-craft Coulomb formation in circular orbits and at libration points; it addresses relative equilibria, stability and optimal reconfigurations of such formations. The relative equilibria of a two-craft tether formation connected by line-of-sight elastic forces moving in circular orbits and at libration points are investigated. In circular Earth orbits and Earth-Moon libration points, the radial, along-track, and orbit normal great circle equilibria conditions are found. An example of modeling the tether force using Coulomb force is discussed. Furthermore, the non-great-circle equilibria conditions for a two-spacecraft tether structure in circular Earth orbit and at collinear libration points are developed. Then the linearized dynamics and stability analysis of a 2-craft Coulomb formation at Earth-Moon libration points are studied. For orbit-radial equilibrium, Coulomb forces control the relative distance between the two satellites. The gravity gradient torques on the formation due to the two planets help stabilize the formation. Similar analysis is performed for along-track and orbit-normal relative equilibrium configurations. Where necessary, the craft use a hybrid thrusting-electrostatic actuation system. The two-craft dynamics at the libration points provide a general framework with circular Earth orbit dynamics forming a special case. In the presence of differential solar drag perturbations, a Lyapunov feedback controller is designed to stabilize a radial equilibrium, two-craft Coulomb formation at collinear libration points. The second part of the thesis investigates optimal reconfigurations of two-craft Coulomb formations in circular Earth orbits by applying nonlinear optimal control techniques. The objective of these reconfigurations is to maneuver the two-craft formation between two charged equilibria configurations. The reconfiguration of spacecraft is posed as an optimization problem using the

Infinite partial summations

International Nuclear Information System (INIS)

Sprung, D.W.L.

1975-01-01

This paper is a brief review of those aspects of the effective interaction problem that can be grouped under the heading of infinite partial summations of the perturbation series. After a brief mention of the classic examples of infinite summations, the author turns to the effective interaction problem for two extra core particles. Their direct interaction is summed to produce the G matrix, while their indirect interaction through the core is summed in a variety of ways under the heading of core polarization. (orig./WL) [de

A cutting- plane approach for semi- infinite mathematical programming

African Journals Online (AJOL)

Many situations ranging from industrial to social via economic and environmental problems may be cast into a Semi-infinite mathematical program. In this paper, the cutting-plane approach which lends itself better for standard non-linear programs is exploited with good reasons for grappling with linear, convex and ...

Thermo-aerodynamic efficiency of non-circular ducts with vortex enhancement of heat exchange in different types of compact heat exchangers

Science.gov (United States)

Vasilev, V. Ya; Nikiforova, S. A.

2018-03-01

Experimental studies of thermo-aerodynamic characteristics of non-circular ducts with discrete turbulators on walls and interrupted channels have confirmed the rational enhancement of convective heat transfer, in which the growth of heat transfer outstrips or equals the growth of aerodynamic losses. Determining the regularities of rational (energy-saving) enhancement of heat transfer and the proposed method for comparing the characteristics of smooth-channel (without enhancement) heat exchangers with effective analogs provide new results, confirming the high efficiency of vortex enhancement of convective heat transfer in non-circular ducts of plate-finned heat exchange surfaces. This allows creating heat exchangers with much smaller mass and volume for operation in energy-saving modes.

Viscous-elastic dynamics of power-law fluids within an elastic cylinder

Science.gov (United States)

Boyko, Evgeniy; Bercovici, Moran; Gat, Amir D.

2017-07-01

In a wide range of applications, microfluidic channels are implemented in soft substrates. In such configurations, where fluidic inertia and compressibility are negligible, the propagation of fluids in channels is governed by a balance between fluid viscosity and elasticity of the surrounding solid. The viscous-elastic interactions between elastic substrates and non-Newtonian fluids are particularly of interest due to the dependence of viscosity on the state of the system. In this work, we study the fluid-structure interaction dynamics between an incompressible non-Newtonian fluid and a slender linearly elastic cylinder under the creeping flow regime. Considering power-law fluids and applying the thin shell approximation for the elastic cylinder, we obtain a nonhomogeneous p-Laplacian equation governing the viscous-elastic dynamics. We present exact solutions for the pressure and deformation fields for various initial and boundary conditions for both shear-thinning and shear-thickening fluids. We show that in contrast to Stokes' problem where a compactly supported front is obtained for shear-thickening fluids, here the role of viscosity is inversed and such fronts are obtained for shear-thinning fluids. Furthermore, we demonstrate that for the case of a step in inlet pressure, the propagation rate of the front has a tn/n +1 dependence on time (t ), suggesting the ability to indirectly measure the power-law index (n ) of shear-thinning liquids through measurements of elastic deformation.

Simplified computational methods for elastic and elastic-plastic fracture problems

Science.gov (United States)

Atluri, Satya N.

1992-01-01

An overview is given of some of the recent (1984-1991) developments in computational/analytical methods in the mechanics of fractures. Topics covered include analytical solutions for elliptical or circular cracks embedded in isotropic or transversely isotropic solids, with crack faces being subjected to arbitrary tractions; finite element or boundary element alternating methods for two or three dimensional crack problems; a 'direct stiffness' method for stiffened panels with flexible fasteners and with multiple cracks; multiple site damage near a row of fastener holes; an analysis of cracks with bonded repair patches; methods for the generation of weight functions for two and three dimensional crack problems; and domain-integral methods for elastic-plastic or inelastic crack mechanics.

Administrative Circulars

CERN Document Server

Département des Ressources humaines

2004-01-01

Administrative Circular N° 2 (Rev. 2) - May 2004 Guidelines and procedures concerning recruitment and probation period of staff members This circular has been revised. It cancels and replaces Administrative Circular N° 2 (Rev. 1) - March 2000. Administrative Circular N° 9 (Rev. 3) - May 2004 Staff members contracts This circular has been revised. It cancels and replaces Administrative Circular N° 9 (Rev. 2) - March 2000. Administrative Circular N° 26 (Rev. 4) - May 2004 Procedure governing the career evolution of staff members This circular has also been revised. It Administrative Circulars Administrative Circular N° 26 (Rev. 3) - December 2001 and brings up to date the French version (Rev. 4) published on the HR Department Web site in January 2004. Operational Circular N° 7 - May 2004 Work from home This circular has been drawn up. Operational Circular N° 8 - May 2004 Dealing with alcohol-related problems...

77 FR 73015 - Circular Welded Non-Alloy Steel Pipe From the Republic of Korea: Preliminary Results of...

Science.gov (United States)

2012-12-07

... Steel Pipe From the Republic of Korea: Preliminary Results of Antidumping Duty Administrative Review... antidumping duty order on circular welded non-alloy steel pipe (CWP) from the Republic of Korea (Korea). The... preliminarily found that one respondent has made sales of the subject merchandise at prices below normal value...

Circular arc structures

KAUST Repository

Bo, Pengbo

2011-07-01

The most important guiding principle in computational methods for freeform architecture is the balance between cost efficiency on the one hand, and adherence to the design intent on the other. Key issues are the simplicity of supporting and connecting elements as well as repetition of costly parts. This paper proposes so-called circular arc structures as a means to faithfully realize freeform designs without giving up smooth appearance. In contrast to non-smooth meshes with straight edges where geometric complexity is concentrated in the nodes, we stay with smooth surfaces and rather distribute complexity in a uniform way by allowing edges in the shape of circular arcs. We are able to achieve the simplest possible shape of nodes without interfering with known panel optimization algorithms. We study remarkable special cases of circular arc structures which possess simple supporting elements or repetitive edges, we present the first global approximation method for principal patches, and we show an extension to volumetric structures for truly threedimensional designs. © 2011 ACM.

Circular RNAs as Promising Biomarkers: A mini-review

Directory of Open Access Journals (Sweden)

Nadiah Abu

2016-08-01

Full Text Available The interest in circular RNAs has resurfaced in the past few years. What was considered as junk for nearly two decades is now one of the most interesting molecules. Circular RNAs are non-coding RNAs that are formed by back-splicing events and have covalently closed loops with no poly-adenylated tails. The regulation of circular RNAs is distinctive and they are selectively abundant in different types of tissues. Based on the current knowledge of circular RNAs, these molecules have the potential to be the next big thing especially as biomarkers for different diseases. This mini-review attempts to concisely look at the biology of circular RNAs, the putative functional activities, the prevalence of circular RNAs, and the possible role of circular RNA as biomarkers for diagnosis or measuring drug response.

Effect of elastic anisotropy of crystal grain on stress intensity factor

Energy Technology Data Exchange (ETDEWEB)

Kamaya, Masayuki [Inst. of Nuclear Safety System Inc., Mihama, Fukui (Japan)

2002-09-01

The stress intensity factor (SIF) is used widely for evaluating integrity of cracked components. Usually, the SIF obtained under isotropic elastic conditions is used for the evaluations. Although, macroscopic elastic behaviors of polycrystal materials can be considered isotropic, each crystal has anisotropic elastic properties. This implies that if the crack size is small and the influence of anisotropic elastic properties on the stress around cracks is significant, the SIF evaluated under anisotropic elastic conditions may differ from the SIF obtained under isotropic elastic conditions. In the present study, the effect of anisotropic elasticity on the SIF was evaluated by using the finite element analysis (FEA). First, the SIF of semi-circular cracks located in a single crystal was evaluated. It was found that the SIF is affected crystal orientation. Secondly, FEA using a polycrystal model was performed. It was found that the change in the SIF was caused by crack tip crystal orientation as well as the deformation constraint from neighboring crystals. Finally, the statistical tendency of change in the SIF caused by the anisotropic elastic properties and the relationship with crack size were examined. The influence of the local SIF on crack growth behavior is also discussed. (author)

Effect of elastic anisotropy of crystal grain on stress intensity factor

International Nuclear Information System (INIS)

Kamaya, Masayuki

2002-01-01

The stress intensity factor (SIF) is used widely for evaluating integrity of cracked components. Usually, the SIF obtained under isotropic elastic conditions is used for the evaluations. Although, macroscopic elastic behaviors of polycrystal materials can be considered isotropic, each crystal has anisotropic elastic properties. This implies that if the crack size is small and the influence of anisotropic elastic properties on the stress around cracks is significant, the SIF evaluated under anisotropic elastic conditions may differ from the SIF obtained under isotropic elastic conditions. In the present study, the effect of anisotropic elasticity on the SIF was evaluated by using the finite element analysis (FEA). First, the SIF of semi-circular cracks located in a single crystal was evaluated. It was found that the SIF is affected crystal orientation. Secondly, FEA using a polycrystal model was performed. It was found that the change in the SIF was caused by crack tip crystal orientation as well as the deformation constraint from neighboring crystals. Finally, the statistical tendency of change in the SIF caused by the anisotropic elastic properties and the relationship with crack size were examined. The influence of the local SIF on crack growth behavior is also discussed. (author)

Vibration due to non-circularity of a rotating ring having discrete radial supports - With application to thin-walled rotor/magnetic bearing systems

Science.gov (United States)

Fakkaew, Wichaphon; Cole, Matthew O. T.

2018-06-01

This paper investigates the vibration arising in a thin-walled cylindrical rotor subject to small non-circularity and coupled to discrete space-fixed radial bearing supports. A Fourier series description of rotor non-circularity is incorporated within a mathematical model for vibration of a rotating annulus. This model predicts the multi-harmonic excitation of the rotor wall due to bearing interactions. For each non-circularity harmonic there is a set of distinct critical speeds at which resonance can potentially arise due to flexural mode excitation within the rotor wall. It is shown that whether each potential resonance occurs depends on the multiplicity and symmetry of the bearing supports. Also, a sufficient number of evenly spaced identical supports will eliminate low order resonances. The considered problem is pertinent to the design and operation of thin-walled rotors with active magnetic bearing (AMB) supports, for which small clearances exist between the rotor and bearing and so vibration excitation must be limited to avoid contacts. With this motivation, the mathematical model is further developed for the case of a distributed array of electromagnetic actuators controlled by feedback of measured rotor wall displacements. A case study involving an experimental system with short cylindrical rotor and a single radial AMB support is presented. The results show that flexural mode resonance is largely avoided for the considered design topology. Moreover, numerical predictions based on measured non-circularity show good agreement with measurements of rotor wall vibration, thereby confirming the validity and utility of the theoretical model.

Infinite time interval backward stochastic differential equations with continuous coefficients.

Science.gov (United States)

Zong, Zhaojun; Hu, Feng

2016-01-01

In this paper, we study the existence theorem for [Formula: see text] [Formula: see text] solutions to a class of 1-dimensional infinite time interval backward stochastic differential equations (BSDEs) under the conditions that the coefficients are continuous and have linear growths. We also obtain the existence of a minimal solution. Furthermore, we study the existence and uniqueness theorem for [Formula: see text] [Formula: see text] solutions of infinite time interval BSDEs with non-uniformly Lipschitz coefficients. It should be pointed out that the assumptions of this result is weaker than that of Theorem 3.1 in Zong (Turkish J Math 37:704-718, 2013).

Effect of kinesiotaping, non-elastic taping and bracing on segmental foot kinematics during drop landing in healthy subjects and subjects with chronic ankle instability.

Science.gov (United States)

Kuni, B; Mussler, J; Kalkum, E; Schmitt, H; Wolf, S I

2016-09-01

To evaluate the effects of kinesiotape, non-elastic tape, and soft brace on segmental foot kinematics during drop landing in subjects with chronic ankle instability and healthy subjects. Controlled study with repeated measurements. Three-dimensional motion analysis laboratory. Twenty participants with chronic ankle instability and 20 healthy subjects. The subjects performed drop landings with 17 retroreflective markers on the foot and lower leg in four conditions: barefoot, with kinesiotape, with non-elastic tape and with a soft brace. Ranges of motion of foot segments using a foot measurement method. In participants with chronic ankle instability, midfoot movement in the frontal plane (inclination of the medial arch) was reduced significantly by non-elastic taping, but kinesiotaping and bracing had no effect. In healthy subjects, both non-elastic taping and bracing reduced that movement. In both groups, non-elastic taping and bracing reduced rearfoot excursion in inversion/eversion significantly, which indicates a stabilisation effect. No such effect was found with kinesiotaping. All three methods reduced maximum plantar flexion significantly. Non-elastic taping stabilised the midfoot best in patients with chronic ankle instability, while kinesiotaping did not influence foot kinematics other than to stabilise the rearfoot in the sagittal plane. ClinicalTrials.gov NCT01810471. Copyright © 2015 Chartered Society of Physiotherapy. Published by Elsevier Ltd. All rights reserved.

Wave propagation in semi-infinite bar with random imperfectios of mass and elasticity module

Czech Academy of Sciences Publication Activity Database

Náprstek, Jiří

2007-01-01

Roč. 310, č. 3 (2007), s. 676-693 ISSN 0022-460X R&D Projects: GA AV ČR(CZ) IAA2071401; GA ČR(CZ) GA103/06/0099 Institutional research plan: CEZ:AV0Z20710524 Keywords : elasticity module * Young modulus * random imperfections Subject RIV: JM - Building Engineering Impact factor: 1.024, year: 2007

75 FR 20342 - Certain Circular Welded Non-Alloy Steel Pipe From Mexico: Final Results of Antidumping Duty...

Science.gov (United States)

2010-04-19

... covered in this review, but was covered in a previous review or the original less-than-fair-value (LTFV... investigation. See Final Determination of Sales at Less Than Fair Value: Circular Welded Non- Alloy Steel Pipe... for framing and support members for reconstruction or load-bearing purposes in the construction...

76 FR 77770 - Certain Circular Welded Non-Alloy Steel Pipe From Mexico: Final Results of Antidumping Duty...

Science.gov (United States)

2011-12-14

... previous review or the original less-than-fair-value (LTFV) investigation, the cash deposit rate will... Determination of Sales at Less Than Fair Value: Circular Welded Non-Alloy Steel Pipe From Mexico, 57 FR 42953... structural pipe tubing used for framing and support members for reconstruction or load-bearing purposes in...

An infinite-dimensional calculus for gauge theories

OpenAIRE

Mendes, Rui Vilela

2010-01-01

A space for gauge theories is defined, using projective limits as subsets of Cartesian products of homomorphisms from a lattice on the structure group. In this space, non-interacting and interacting measures are defined as well as functions and operators. From projective limits of test functions and distributions on products of compact groups, a projective gauge triplet is obtained, which provides a framework for the infinite-dimensional calculus in gauge theories. The gauge measure behavior ...

Limit Laws and Recurrence for the Planar Lorentz Process with Infinite Horizon

CERN Document Server

Szász, D

2006-01-01

As Bleher observed the free flight vector of the planar, infinite horizon, periodic Lorentz process $\\{S_n | n=0, 1, 2, \\dots \\}$ belongs to the non-standard domain of attraction of the Gaussian law --- actually with the $\\sqrt{n \\log n}$ scaling. Our first aim is to establish his conjecture that, indeed, $\\frac{S_n}{\\sqrt{n \\log n}}$ converges in distribution to the Gaussian law (a Global Limit Theorem). Here the recent method of B\\'alint and Gou\\"ezel, \\cite{BG} helped us to essentially simplify the ideas of our earlier sketchy proof. Moreover, we can also derive a.) the local version of the Global Limit Theorem, b.) the recurrence of the planar, infinite horizon, periodic Lorentz process, and finally c.) the ergodicity of its infinite invariant measure.

Circular polarization in a non-magnetic resonant tunneling device

Directory of Open Access Journals (Sweden)

Airey Robert

2011-01-01

Full Text Available Abstract We have investigated the polarization-resolved photoluminescence (PL in an asymmetric n-type GaAs/AlAs/GaAlAs resonant tunneling diode under magnetic field parallel to the tunnel current. The quantum well (QW PL presents strong circular polarization (values up to -70% at 19 T. The optical emission from GaAs contact layers shows evidence of highly spin-polarized two-dimensional electron and hole gases which affects the spin polarization of carriers in the QW. However, the circular polarization degree in the QW also depends on various other parameters, including the g-factors of the different layers, the density of carriers along the structure, and the Zeeman and Rashba effects.

The nominalized infinitive in French : structure and change

Directory of Open Access Journals (Sweden)

Petra Sleeman

2010-01-01

Full Text Available Many European languages have both nominal and verbal nominalized infinitives. They differ, however, in the degree to which the nominalized infinitives possess nominal and verbal properties. In this paper, nominalized infinitives in French are analyzed. It is shown that, whereas Old French was like other Romance languages in possessing both nominal and verbal nominalized infinitives, Modern French differs parametrically from other Romance languages in not having verbal infinitives and in allowing nominal infinitives only in a scientific style of speech. An analysis is proposed, within a syntactic approach to morphology. that tries to account for the loss of the verbal properties of the nominalized infinitive in French. It is proposed that the loss results from a change in word order (the loss of the OV word order in favor of the VO word order and a change in the morphological analysis of the nominalized infinitive: instead of a zero suffix analysis, a derivational analysis was adopted by the speakers of French. It is argued that the derivational analysis restricted nominalization to Vo, which made nominalization of infinitives less ìverbalî than in other Romance languages

Rayleigh-Taylor instability in accelerated elastic-solid slabs

Science.gov (United States)

Piriz, S. A.; Piriz, A. R.; Tahir, N. A.

2017-12-01

We develop the linear theory for the asymptotic growth of the incompressible Rayleigh-Taylor instability of an accelerated solid slab of density ρ2, shear modulus G , and thickness h , placed over a semi-infinite ideal fluid of density ρ110.1007/s000330050121] to arbitrary values of AT and unveil the singular feature of an instability threshold below which the slab is stable for any perturbation wavelength. As a consequence, an accelerated elastic-solid slab is stable if ρ2g h /G ≤2 (1 -AT) /AT .

Semi-infinite fractional programming

CERN Document Server

Verma, Ram U

2017-01-01

This book presents a smooth and unified transitional framework from generalised fractional programming, with a finite number of variables and a finite number of constraints, to semi-infinite fractional programming, where a number of variables are finite but with infinite constraints. It focuses on empowering graduate students, faculty and other research enthusiasts to pursue more accelerated research advances with significant interdisciplinary applications without borders. In terms of developing general frameworks for theoretical foundations and real-world applications, it discusses a number of new classes of generalised second-order invex functions and second-order univex functions, new sets of second-order necessary optimality conditions, second-order sufficient optimality conditions, and second-order duality models for establishing numerous duality theorems for discrete minmax (or maxmin) semi-infinite fractional programming problems.   In the current interdisciplinary supercomputer-oriented research envi...

Ambiguities about infinite nuclear matter

International Nuclear Information System (INIS)

Fabre de la Ripelle, M.

1978-01-01

Exact solutions of the harmonic-oscillator and infinite hyperspherical well are given for the ground state of a infinitely heavy (N=Z) nucleus. The density of matter is a steadily decreasing function. The kinetic energy per particle is 12% smaller than the one predicted by the Fermi sea

Derivation Method for the Foundation Boundaries of Hydraulic Numerical Simulation Models Based on the Elastic Boussinesq Solution

Directory of Open Access Journals (Sweden)

Jintao Song

2015-01-01

Full Text Available The foundation boundaries of numerical simulation models of hydraulic structures dominated by a vertical load are investigated. The method used is based on the stress formula for fundamental solutions to semi-infinite space body elastic mechanics under a vertical concentrated force. The limit method is introduced into the original formula, which is then partitioned and analyzed according to the direction of the depth extension of the foundation. The point load will be changed to a linear load with a length of 2a. Inverse proportion function assumptions are proposed at parameter a and depth l of the calculation points to solve the singularity questions of elastic stress in a semi-infinite space near the ground. Compared with the original formula, changing the point load to a linear load with a length of 2a is more reasonable. Finally, the boundary depth criterion of a hydraulic numerical simulation model is derived and applied to determine the depth boundary formula for gravity dam numerical simulations.

On the use of elastic-plastic material characteristics for linear-elastic component assessments

International Nuclear Information System (INIS)

Kussmaul, K.; Silcher, H.; Eisele, U.

1995-01-01

In this paper the procedure of safety assessment of components by fracture mechanics analysis as recommended in TECDOC 717 is applied to two standard specimens of ductile cast iron. It is shown that the use of a pseudo-elastic K IJ -value in linear elastic safety analysis may lead to non-conservative results, when elastic-plastic material behaviour can be expected. (author)

Stochastic and infinite dimensional analysis

CERN Document Server

Carpio-Bernido, Maria; Grothaus, Martin; Kuna, Tobias; Oliveira, Maria; Silva, José

2016-01-01

This volume presents a collection of papers covering applications from a wide range of systems with infinitely many degrees of freedom studied using techniques from stochastic and infinite dimensional analysis, e.g. Feynman path integrals, the statistical mechanics of polymer chains, complex networks, and quantum field theory. Systems of infinitely many degrees of freedom create their particular mathematical challenges which have been addressed by different mathematical theories, namely in the theories of stochastic processes, Malliavin calculus, and especially white noise analysis. These proceedings are inspired by a conference held on the occasion of Prof. Ludwig Streit’s 75th birthday and celebrate his pioneering and ongoing work in these fields.

The Infinitive Marker across Scandinavian

DEFF Research Database (Denmark)

Christensen, Ken Ramshøj

2007-01-01

In this paper I argue that the base-position of the infinitive marker in the Scandinavian languages and English share a common origin site. It is inserted as the top-most head in the VP-domain. The cross-linguistic variation in the syntactic distribution of the infinitive marker can be accounted...

Influence of non-integer-order derivatives on unsteady unidirectional motions of an Oldroyd-B fluid with generalized boundary conditions

Science.gov (United States)

Zafar, A. A.; Riaz, M. B.; Shah, N. A.; Imran, M. A.

2018-03-01

The objective of this article is to study some unsteady Couette flows of an Oldroyd-B fluid with non-integer derivatives. The fluid fills an annular region of two infinite co-axial circular cylinders. Flows are due to the motion of the outer cylinder, that rotates about its axis with an arbitrary time-dependent velocity while the inner cylinder is held fixed. Closed form solutions of dimensionless velocity field and tangential tension are obtained by means of the finite Hankel transform and the theory of Laplace transform for fractional calculus. Several results in the literature including the rotational flows through an infinite cylinder can be obtained as limiting cases of our general solutions. Finally, the control of the fractional framework on the dynamics of fluid is analyzed by numerical simulations and graphical illustrations.

Survival analysis, the infinite Gaussian mixture model, FDG-PET and non-imaging data in the prediction of progression from mild cognitive impairment

OpenAIRE

Li, Rui; Perneczky, Robert; Drzezga, Alexander; Kramer, Stefan; Initiative, for the Alzheimer's Disease Neuroimaging

2015-01-01

We present a method to discover interesting brain regions in [18F] fluorodeoxyglucose positron emission tomography (PET) scans, showing also the benefits when PET scans are in combined use with non-imaging variables. The discriminative brain regions facilitate a better understanding of Alzheimer's disease (AD) progression, and they can also be used for predicting conversion from mild cognitive impairment (MCI) to AD. A survival analysis(Cox regression) and infinite Gaussian mixture model (IGM...

Teleportation schemes in infinite dimensional Hilbert spaces

International Nuclear Information System (INIS)

Fichtner, Karl-Heinz; Freudenberg, Wolfgang; Ohya, Masanori

2005-01-01

The success of quantum mechanics is due to the discovery that nature is described in infinite dimension Hilbert spaces, so that it is desirable to demonstrate the quantum teleportation process in a certain infinite dimensional Hilbert space. We describe the teleportation process in an infinite dimensional Hilbert space by giving simple examples

Size Effects on Surface Elastic Waves in a Semi-Infinite Medium with Atomic Defect Generation

Directory of Open Access Journals (Sweden)

F. Mirzade

2013-01-01

Full Text Available The paper investigates small-scale effects on the Rayleigh-type surface wave propagation in an isotopic elastic half-space upon laser irradiation. Based on Eringen’s theory of nonlocal continuum mechanics, the basic equations of wave motion and laser-induced atomic defect dynamics are derived. Dispersion equation that governs the Rayleigh surface waves in the considered medium is derived and analyzed. Explicit expressions for phase velocity and attenuation (amplification coefficients which characterize surface waves are obtained. It is shown that if the generation rate is above the critical value, due to concentration-elastic instability, nanometer sized ordered concentration-strain structures on the surface or volume of solids arise. The spatial scale of these structures is proportional to the characteristic length of defect-atom interaction and increases with the increase of the temperature of the medium. The critical value of the pump parameter is directly proportional to recombination rate and inversely proportional to deformational potentials of defects.

Properties of semi-infinite nuclei

International Nuclear Information System (INIS)

El-Jaick, L.J.; Kodama, T.

1976-04-01

Several relations among density distributions and energies of semi-infinite and infinite nuclei are iventigated in the framework of Wilets's statistical model. The model is shown to be consistent with the theorem of surface tension given by Myers and Swiatecki. Some numerical results are shown by using an appropriate nuclear matter equation of state

75 FR 44763 - Certain Circular Welded Non-Alloy Steel Pipe From Mexico; Extension of Time Limit for Preliminary...

Science.gov (United States)

2010-07-29

...-Alloy Steel Pipe From Mexico; Extension of Time Limit for Preliminary Results of Antidumping Duty... review of the antidumping duty order on certain circular welded non- alloy steel pipe from Mexico. We... preliminary results of this review within the original time frame because we require additional time with...

Topology preserving non-rigid image registration using time-varying elasticity model for MRI brain volumes.

Science.gov (United States)

Ahmad, Sahar; Khan, Muhammad Faisal

2015-12-01

In this paper, we present a new non-rigid image registration method that imposes a topology preservation constraint on the deformation. We propose to incorporate the time varying elasticity model into the deformable image matching procedure and constrain the Jacobian determinant of the transformation over the entire image domain. The motion of elastic bodies is governed by a hyperbolic partial differential equation, generally termed as elastodynamics wave equation, which we propose to use as a deformation model. We carried out clinical image registration experiments on 3D magnetic resonance brain scans from IBSR database. The results of the proposed registration approach in terms of Kappa index and relative overlap computed over the subcortical structures were compared against the existing topology preserving non-rigid image registration methods and non topology preserving variant of our proposed registration scheme. The Jacobian determinant maps obtained with our proposed registration method were qualitatively and quantitatively analyzed. The results demonstrated that the proposed scheme provides good registration accuracy with smooth transformations, thereby guaranteeing the preservation of topology. Copyright © 2015 Elsevier Ltd. All rights reserved.

Symmetric Circular Matchings and RNA Folding

DEFF Research Database (Denmark)

Hofacker, Ivo L.; Reidys, Christian; Stadler, Peter F.

2012-01-01

RNA secondary structures can be computed as optimal solutions of certain circular matching problems. An accurate treatment of this energy minimization problem has to account for the small --- but non-negligible --- entropic destabilization of secondary structures with non-trivial automorphisms. S...

Steady-state, elastic-plastic growth of slanted cracks in symmetrically loaded plates

DEFF Research Database (Denmark)

Nielsen, Kim Lau; Hutchinson, J. W.

2017-01-01

parameter through the plate in the plastic zone at the crack tip. The distribution of the mode I and mode III stress intensity factors along the crack front are obtained for the elastic problem. The out-of-plane bending constraint imposed on the plate significantly influences the mixed mode behavior along......Elastic and elastic-plastic results are obtained for a semi-infinite slanted through-crack propagating in a symmetrically loaded plate strip with the aim of providing theoretical background to commonly observed plate tearing behavior. Were it is not for the slant of the crack through the thickness...... of the plate, the problem would be mode I, but due to the slant the local conditions along the crack front are a combination of mode I and mode III. A three-dimensional formulation for steady-state crack propagation is employed to generate distributions of effective stress, stress triaxiality and Lode...

First Principles Calculations for X-ray Resonant Spectra and Elastic Properties

International Nuclear Information System (INIS)

Yongbin Lee

2006-01-01

In this thesis, we discuss applications of first principles methods to x-ray resonant spectra and elastic properties calculation. We start with brief reviews about theoretical background of first principles methods, such as density functional theory, local density approximation (LDA), LDA+U, and the linear augmented plane wave (LAPW) method to solve Kohn-Sham equations. After that we discuss x-ray resonant scattering (XRMS), x-ray magnetic circular dichroism (XMCD) and the branching problem in the heavy rare earths Ledges. In the last chapter we discuss the elastic properties of the second hardest material AlMgB 14

Oscillations of a Beam on a Non-Linear Elastic Foundation under Periodic Loads

Directory of Open Access Journals (Sweden)

Donald Mark Santee

2006-01-01

Full Text Available The complexity of the response of a beam resting on a nonlinear elastic foundation makes the design of this structural element rather challenging. Particularly because, apparently, there is no algebraic relation for its load bearing capacity as a function of the problem parameters. Such an algebraic relation would be desirable for design purposes. Our aim is to obtain this relation explicitly. Initially, a mathematical model of a flexible beam resting on a non-linear elastic foundation is presented, and its non-linear vibrations and instabilities are investigated using several numerical methods. At a second stage, a parametric study is carried out, using analytical and semi-analytical perturbation methods. So, the influence of the various physical and geometrical parameters of the mathematical model on the non-linear response of the beam is evaluated, in particular, the relation between the natural frequency and the vibration amplitude and the first period doubling and saddle-node bifurcations. These two instability phenomena are the two basic mechanisms associated with the loss of stability of the beam. Finally Melnikov's method is used to determine an algebraic expression for the boundary that separates a safe from an unsafe region in the force parameters space. It is shown that this can be used as a basis for a reliable engineering design criterion.

Large deviations for noninteracting infinite-particle systems

International Nuclear Information System (INIS)

Donsker, M.D.; Varadhan, S.R.S.

1987-01-01

A large deviation property is established for noninteracting infinite particle systems. Previous large deviation results obtained by the authors involved a single I-function because the cases treated always involved a unique invariant measure for the process. In the context of this paper there is an infinite family of invariant measures and a corresponding infinite family of I-functions governing the large deviations

Wave propagation in semi-infinite bar with random imperfections of density and elasticity module

Czech Academy of Sciences Publication Activity Database

Náprstek, Jiří

2008-01-01

Roč. 310, č. 3 (2008), s. 676-693 ISSN 0022-460X R&D Projects: GA ČR(CZ) GA103/06/0099; GA AV ČR(CZ) IAA2071401 Institutional research plan: CEZ:AV0Z20710524 Keywords : correlation methods * elastic moduli * finite element method * random processes Subject RIV: JM - Building Engineering Impact factor: 1.364, year: 2008 http://www.sciencedirect.com/science/article/pii/S0022460X07002374?np=y

On liquid vibration in elastic containers

International Nuclear Information System (INIS)

Priehn, F.

1984-01-01

Numerical methods of calculation for containers made of circular rings of any crossection are derived for containers which are filled with incompressible and also with compressible liquids. This is done neglecting the formation of waves on the liquid surface, and by using a simplified mechanical model for calculations for the elastic walls. Using a developed Fourier series in the circumferential direction, this leads to a plane model and one obtains a very compact system of equations, which give an opportunity of studying the individual effects very economically. (orig./HP) [de

Comparative studies of parameters based on the most probable versus an approximate linear extrapolation distance estimates for circular cylindrical absorbing rod

International Nuclear Information System (INIS)

Wassef, W.A.

1982-01-01

Estimates and techniques that are valid to calculate the linear extrapolation distance for an infinitely long circular cylindrical absorbing region are reviewed. Two estimates, in particular, are put into consideration, that is the most probable and the value resulting from an approximate technique based on matching the integral transport equation inside the absorber with the diffusion approximation in the surrounding infinite scattering medium. Consequently, the effective diffusion parameters and the blackness of the cylinder are derived and subjected to comparative studies. A computer code is set up to calculate and compare the different parameters, which is useful in reactor analysis and serves to establish a beneficial estimates that are amenable to direct application to reactor design codes

Stress-intensity factors for cracks emanating from the loaded fastener hole

Science.gov (United States)

Shivakumar, V.; Hsu, Y. C.

1977-01-01

Using a series approach and the Muskhelishvili formulation in the two-dimensional theory of elasticity, stress-intensity factors K are derived for problems in which cracks emanate radially from the boundary of an arbitrarily loaded internal circular hole in an infinite plate. Numerical values are obtained for K(I) and K(II) for radial cracks from a hole containing a loose-fitted pin or rivet that is pulled perpendicular to the crack direction in the plane of the plate. The method is a general one for determining K for a set of symmetrically emanating radial cracks for a variety of concentrated or distributed tractions on the circular hole.

The pion-deuteron forward elastic amplitude in the non-overlapping potentials model

International Nuclear Information System (INIS)

Butterworth, D.S.

1978-01-01

The pion-deuteron forward elastic amplitude has been calculated in the non-overlapping potentials model, which enables a description of off-shell propagation effects in terms of on-shell amplitudes. Calculations include spin, isospin and deuteron D-state probability effects. Two energy regions are considered. First the pion-nucleon P 33 resonance region, where, using a formalism developed by Agassi and Gal (Ann. Phys.; 75:56 (1973) and 94:184 (1975)), the full multiple-scattering series is summed in an approximation of P 33 wave dominance of the higher-order scatterings. Second, for the subsequent highest-energy region, the double-scattering term only is calculated. Fermi smearing effects are included in both cases. Predictions for the total cross section, its dependence on the deuteron alignment and the real part of the forward elastic amplitude are compared with those of Glauber theory, and data where available. Convergence of the multiple-scattering series is also discussed. (author)

Proving productivity in infinite data structures

NARCIS (Netherlands)

Zantema, H.; Raffelsieper, M.; Lynch, C.

2010-01-01

For a general class of infinite data structures including streams, binary trees, and the combination of finite and infinite lists, we investigate the notion of productivity. This generalizes stream productivity. We develop a general technique to prove productivity based on proving context-sensitive

Variational Infinite Hidden Conditional Random Fields

NARCIS (Netherlands)

Bousmalis, Konstantinos; Zafeiriou, Stefanos; Morency, Louis-Philippe; Pantic, Maja; Ghahramani, Zoubin

2015-01-01

Hidden conditional random fields (HCRFs) are discriminative latent variable models which have been shown to successfully learn the hidden structure of a given classification problem. An Infinite hidden conditional random field is a hidden conditional random field with a countably infinite number of

Transient thermal stresses due to a zonal heat source moving back and forth over the surface on an infinite plate

International Nuclear Information System (INIS)

Sumi, N.; Hetnarski, R.B.

1989-01-01

A solution is given for the transient thermal stresses due to a zonal heat source moving back and forth with a constant angular frequency over the surface of an infinite elastic plate. The transient temperature distribution is obtained by using the complex Fourier and Laplace transforms, and the associated thermal stresses are obtained by means of the thermoelastic displacement potential and the Galerkin function. Graphical representations for the solution in dimensionless terms are included in this paper. (orig.)

Maximum a posteriori probability estimates in infinite-dimensional Bayesian inverse problems

International Nuclear Information System (INIS)

Helin, T; Burger, M

2015-01-01

A demanding challenge in Bayesian inversion is to efficiently characterize the posterior distribution. This task is problematic especially in high-dimensional non-Gaussian problems, where the structure of the posterior can be very chaotic and difficult to analyse. Current inverse problem literature often approaches the problem by considering suitable point estimators for the task. Typically the choice is made between the maximum a posteriori (MAP) or the conditional mean (CM) estimate. The benefits of either choice are not well-understood from the perspective of infinite-dimensional theory. Most importantly, there exists no general scheme regarding how to connect the topological description of a MAP estimate to a variational problem. The recent results by Dashti and others (Dashti et al 2013 Inverse Problems 29 095017) resolve this issue for nonlinear inverse problems in Gaussian framework. In this work we improve the current understanding by introducing a novel concept called the weak MAP (wMAP) estimate. We show that any MAP estimate in the sense of Dashti et al (2013 Inverse Problems 29 095017) is a wMAP estimate and, moreover, how the wMAP estimate connects to a variational formulation in general infinite-dimensional non-Gaussian problems. The variational formulation enables to study many properties of the infinite-dimensional MAP estimate that were earlier impossible to study. In a recent work by the authors (Burger and Lucka 2014 Maximum a posteriori estimates in linear inverse problems with logconcave priors are proper bayes estimators preprint) the MAP estimator was studied in the context of the Bayes cost method. Using Bregman distances, proper convex Bayes cost functions were introduced for which the MAP estimator is the Bayes estimator. Here, we generalize these results to the infinite-dimensional setting. Moreover, we discuss the implications of our results for some examples of prior models such as the Besov prior and hierarchical prior. (paper)

Single particle dynamics in circular accelerators

International Nuclear Information System (INIS)

Ruth, R.D.

1986-10-01

The purpose of this paper is to introduce the reader to the theory associated with the transverse dynamics of single particle, in circular accelerators. The discussion begins with a review of Hamiltonian dynamics and canonical transformations. The case of a single particle in a circular accelerator is considered with a discussion of non-linear terms and chromaticity. The canonical perturbation theory is presented and nonlinear resonances are considered. Finally, the concept of renormalization and residue criterion are examined. (FI)

A class of stochastic games with infinitely many interacting agents related to Glauber dynamics on random graphs

International Nuclear Information System (INIS)

De Santis, Emilio; Marinelli, Carlo

2007-01-01

We introduce and study a class of infinite-horizon non-zero-sum non-cooperative stochastic games with infinitely many interacting agents using ideas of statistical mechanics. First we show, in the general case of asymmetric interactions, the existence of a strategy that allows any player to eliminate losses after a finite random time. In the special case of symmetric interactions, we also prove that, as time goes to infinity, the game converges to a Nash equilibrium. Moreover, assuming that all agents adopt the same strategy, using arguments related to those leading to perfect simulation algorithms, spatial mixing and ergodicity are proved. In turn, ergodicity allows us to prove 'fixation', i.e. players will adopt a constant strategy after a finite time. The resulting dynamics is related to zero-temperature Glauber dynamics on random graphs of possibly infinite volume

Quantum diffusion in semi-infinite periodic and quasiperiodic systems

International Nuclear Information System (INIS)

Zhang Kaiwang

2008-01-01

This paper studies quantum diffusion in semi-infinite one-dimensional periodic lattice and quasiperiodic Fibonacci lattice. It finds that the quantum diffusion in the semi-infinite periodic lattice shows the same properties as that for the infinite periodic lattice. Different behaviour is found for the semi-infinite Fibonacci lattice. In this case, there are still C(t) ∼ t −δ and d(t) ∼ t β . However, it finds that 0 < δ < 1 for smaller time, and δ = 0 for larger time due to the influence of surface localized states. Moreover, β for the semi-infinite Fibonacci lattice is much smaller than that for the infinite Fibonacci lattice. Effects of disorder on the quantum diffusion are also discussed

Nonlinear analysis of the inflation of an initially flat, circular, elastic disk

International Nuclear Information System (INIS)

Christensen, R.M.; Feng, W.W.

1986-01-01

An approximate analysis is given for the inflation of a thin, flat circular disk of elastomeric material. The analysis results in a closed-form analytical solution for the maximum displacement as a function of pressure. The method is illustrated through the use of a Mooney-Rivlin material model. The results are compared with the exact solution, obtained by numerical means, and they are satisfactory, up into the range of several hundred percent strain. The method greatly simplifies the procedure for reducing test data, from this type of test, to nonlinear range mechanical properties

Semi-infinite Weil complex and the Virasoro algebra

International Nuclear Information System (INIS)

Feigin, B.; Frenkel, E.

1991-01-01

We define a semi-infinite analogue of the Weil algebra associated with an infinite-dimensional Lie algebra. It can be used for the definition of semi-infinite characteristic classes by analogy with the Chern-Weil construction. The second term of a spectral sequence of this Weil complex consists of the semi-infinite cohomology of the Lie algebra with coefficients in its 'adjoint semi-infinite symmetric powers'. We compute this cohomology for the Virasoro algebra. This is just the BRST cohomology of the bosonic βγ-system with the central charge 26. We give a complete description of the Fock representations of this bosonic system as modules over the Virasoro algebra, using Friedan-Martinec-Shenker bosonization. We derive a combinatorial identity from this result. (orig.)

Smooth controllability of infinite-dimensional quantum-mechanical systems

International Nuclear Information System (INIS)

Wu, Re-Bing; Tarn, Tzyh-Jong; Li, Chun-Wen

2006-01-01

Manipulation of infinite-dimensional quantum systems is important to controlling complex quantum dynamics with many practical physical and chemical backgrounds. In this paper, a general investigation is casted to the controllability problem of quantum systems evolving on infinite-dimensional manifolds. Recognizing that such problems are related with infinite-dimensional controllability algebras, we introduce an algebraic mathematical framework to describe quantum control systems possessing such controllability algebras. Then we present the concept of smooth controllability on infinite-dimensional manifolds, and draw the main result on approximate strong smooth controllability. This is a nontrivial extension of the existing controllability results based on the analysis over finite-dimensional vector spaces to analysis over infinite-dimensional manifolds. It also opens up many interesting problems for future studies

Negating the Infinitive in Biblical Hebrew

DEFF Research Database (Denmark)

Ehrensvärd, Martin Gustaf

1999-01-01

The article examines the negating of the infinitive in biblical and post-biblical Hebrew. The combination of the negation ayin with infinitive is widely claimed to belong to the linguistic layer commonly referred to as late biblical Hebrew and scholars use it to late-date texts. The article showa...

Improving the Instruction of Infinite Series

Science.gov (United States)

Lindaman, Brian; Gay, A. Susan

2012-01-01

Calculus instructors struggle to teach infinite series, and students have difficulty understanding series and related concepts. Four instructional strategies, prominently used during the calculus reform movement, were implemented during a 3-week unit on infinite series in one class of second-semester calculus students. A description of each…

Supersolids: Solids Having Finite Volume and Infinite Surfaces.

Science.gov (United States)

Love, William P.

1989-01-01

Supersolids furnish an ideal introduction to the calculus topic of infinite series, and are useful for combining that topic with integration. Five examples of supersolids are presented, four requiring only a few basic properties of infinite series and one requiring a number of integration principles as well as infinite series. (MNS)

Feedback control of horizontal position and plasma surface shape in a non-circular tokamak

International Nuclear Information System (INIS)

Moriyama, Shin-ichi; Nakamura, Kazuo; Nakamura, Yukio; Itoh, Satoshi

1986-01-01

The linear model for the coupled horizontal position and plasma surface shape control in the non-circular tokamak device was described. It enables us to estimate easily the displacement and the distortion due to the changes in plasma pressure and current density distribution. The PI-controller and the optimal regulator were designed with the linear model. Transient-response analysis of the control system in the TRIAM-1M tokamak showed that the optimal regulator is superior to the PI-controller with regard to the mutual-interference between the position control system and the elongation control system. (author)

On infinite-dimensional state spaces

International Nuclear Information System (INIS)

Fritz, Tobias

2013-01-01

It is well known that the canonical commutation relation [x, p]=i can be realized only on an infinite-dimensional Hilbert space. While any finite set of experimental data can also be explained in terms of a finite-dimensional Hilbert space by approximating the commutation relation, Occam's razor prefers the infinite-dimensional model in which [x, p]=i holds on the nose. This reasoning one will necessarily have to make in any approach which tries to detect the infinite-dimensionality. One drawback of using the canonical commutation relation for this purpose is that it has unclear operational meaning. Here, we identify an operationally well-defined context from which an analogous conclusion can be drawn: if two unitary transformations U, V on a quantum system satisfy the relation V −1 U 2 V=U 3 , then finite-dimensionality entails the relation UV −1 UV=V −1 UVU; this implication strongly fails in some infinite-dimensional realizations. This is a result from combinatorial group theory for which we give a new proof. This proof adapts to the consideration of cases where the assumed relation V −1 U 2 V=U 3 holds only up to ε and then yields a lower bound on the dimension.

On infinite-dimensional state spaces

Science.gov (United States)

Fritz, Tobias

2013-05-01

It is well known that the canonical commutation relation [x, p] = i can be realized only on an infinite-dimensional Hilbert space. While any finite set of experimental data can also be explained in terms of a finite-dimensional Hilbert space by approximating the commutation relation, Occam's razor prefers the infinite-dimensional model in which [x, p] = i holds on the nose. This reasoning one will necessarily have to make in any approach which tries to detect the infinite-dimensionality. One drawback of using the canonical commutation relation for this purpose is that it has unclear operational meaning. Here, we identify an operationally well-defined context from which an analogous conclusion can be drawn: if two unitary transformations U, V on a quantum system satisfy the relation V-1U2V = U3, then finite-dimensionality entails the relation UV-1UV = V-1UVU; this implication strongly fails in some infinite-dimensional realizations. This is a result from combinatorial group theory for which we give a new proof. This proof adapts to the consideration of cases where the assumed relation V-1U2V = U3 holds only up to ɛ and then yields a lower bound on the dimension.

Kuramoto model for infinite graphs with kernels

KAUST Repository

Canale, Eduardo

2015-01-07

In this paper we study the Kuramoto model of weakly coupled oscillators for the case of non trivial network with large number of nodes. We approximate of such configurations by a McKean-Vlasov stochastic differential equation based on infinite graph. We focus on circulant graphs which have enough symmetries to make the computations easier. We then focus on the asymptotic regime where an integro-partial differential equation is derived. Numerical analysis and convergence proofs of the Fokker-Planck-Kolmogorov equation are conducted. Finally, we provide numerical examples that illustrate the convergence of our method.

Circular RNA profiling reveals that circular RNAs from ANXA2 can be used as new biomarkers for multiple sclerosis.

Science.gov (United States)

Iparraguirre, Leire; Muñoz-Culla, Maider; Prada-Luengo, Iñigo; Castillo-Triviño, Tamara; Olascoaga, Javier; Otaegui, David

2017-09-15

Multiple sclerosis is an autoimmune disease, with higher prevalence in women, in whom the immune system is dysregulated. This dysregulation has been shown to correlate with changes in transcriptome expression as well as in gene-expression regulators, such as non-coding RNAs (e.g. microRNAs). Indeed, some of these have been suggested as biomarkers for multiple sclerosis even though few biomarkers have reached the clinical practice. Recently, a novel family of non-coding RNAs, circular RNAs, has emerged as a new player in the complex network of gene-expression regulation. MicroRNA regulation function through a 'sponge system' and a RNA splicing regulation function have been proposed for the circular RNAs. This regulating role together with their high stability in biofluids makes them seemingly good candidates as biomarkers. Given the dysregulation of both protein-coding and non-coding transcriptome that have been reported in multiple sclerosis patients, we hypothesised that circular RNA expression may also be altered. Therefore, we carried out expression profiling of 13.617 circular RNAs in peripheral blood leucocytes from multiple sclerosis patients and healthy controls finding 406 differentially expressed (P-value  1.5) and demonstrate after validation that, circ_0005402 and circ_0035560 are underexpressed in multiple sclerosis patients and could be used as biomarkers of the disease. © The Author 2017. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Circular Coinduction

Science.gov (United States)

Rosu, Grigore; Goguen, Joseph; Norvig, Peter (Technical Monitor)

2001-01-01

Circular coinduction is a technique for behavioral reasoning that extends cobasis coinduction to specifications with circularities. Because behavioral satisfaction is not recursively enumerable, no algorithm can work for every behavioral statement. However. algorithms using circular coinduction can prove every practical behavioral result that we know. This paper proves the correctness of circular coinduction and some consequences.

Dynamics and elastic interactions of the discrete multi-dark soliton solutions for the Kaup-Newell lattice equation

Science.gov (United States)

Liu, Nan; Wen, Xiao-Yong

2018-03-01

Under consideration in this paper is the Kaup-Newell (KN) lattice equation which is an integrable discretization of the KN equation. Infinitely, many conservation laws and discrete N-fold Darboux transformation (DT) for this system are constructed and established based on its Lax representation. Via the resulting N-fold DT, the discrete multi-dark soliton solutions in terms of determinants are derived from non-vanishing background. Propagation and elastic interaction structures of such solitons are shown graphically. Overtaking interaction phenomena between/among the two, three and four solitons are discussed. Numerical simulations are used to explore their dynamical behaviors of such multi-dark solitons. Numerical results show that their evolutions are stable against a small noise. Results in this paper might be helpful for understanding the propagation of nonlinear Alfvén waves in plasmas.

Semi-exact solution of elastic non-uniform thickness and density rotating disks by homotopy perturbation and Adomian's decomposition methods. Part I: Elastic solution

International Nuclear Information System (INIS)

Hojjati, M.H.; Jafari, S.

2008-01-01

In this work, two powerful analytical methods, namely homotopy perturbation method (HPM) and Adomian's decomposition method (ADM), are introduced to obtain distributions of stresses and displacements in rotating annular elastic disks with uniform and variable thicknesses and densities. The results obtained by these methods are then compared with the verified variational iteration method (VIM) solution. He's homotopy perturbation method which does not require a 'small parameter' has been used and a homotopy with an imbedding parameter p element of [0,1] is constructed. The method takes the full advantage of the traditional perturbation methods and the homotopy techniques and yields a very rapid convergence of the solution. Adomian's decomposition method is an iterative method which provides analytical approximate solutions in the form of an infinite power series for nonlinear equations without linearization, perturbation or discretization. Variational iteration method, on the other hand, is based on the incorporation of a general Lagrange multiplier in the construction of correction functional for the equation. This study demonstrates the ability of the methods for the solution of those complicated rotating disk cases with either no or difficult to find fairly exact solutions without the need to use commercial finite element analysis software. The comparison among these methods shows that although the numerical results are almost the same, HPM is much easier, more convenient and efficient than ADM and VIM

Accuracy and repeatability positioning of high-performancel athe for non-circular turning

Directory of Open Access Journals (Sweden)

Majda Paweł

2017-11-01

Full Text Available This paper presents research on the accuracy and repeatability of CNC axis positioning in an innovative lathe with an additional Xs axis. This axis is used to perform movements synchronized with the angular position of the main drive, i.e. the spindle, and with the axial feed along the Z axis. This enables the one-pass turning of non-circular surfaces, rope and trapezoidal threads, as well as the surfaces of rotary tools such as a gear cutting hob, etc. The paper presents and discusses the interpretation of results and the calibration effects of positioning errors in the lathe’s numerical control system. Finally, it shows the geometric characteristics of the rope thread turned at various spindle speeds, including before and after-correction of the positioning error of the Xs axis.

Accuracy and repeatability positioning of high-performancel athe for non-circular turning

Science.gov (United States)

Majda, Paweł; Powałka, Bartosz

2017-11-01

This paper presents research on the accuracy and repeatability of CNC axis positioning in an innovative lathe with an additional Xs axis. This axis is used to perform movements synchronized with the angular position of the main drive, i.e. the spindle, and with the axial feed along the Z axis. This enables the one-pass turning of non-circular surfaces, rope and trapezoidal threads, as well as the surfaces of rotary tools such as a gear cutting hob, etc. The paper presents and discusses the interpretation of results and the calibration effects of positioning errors in the lathe's numerical control system. Finally, it shows the geometric characteristics of the rope thread turned at various spindle speeds, including before and after-correction of the positioning error of the Xs axis.

Impact loads on beams on elastic foundations

International Nuclear Information System (INIS)

Kameswara Rao, N.S.V.; Prasad, B.B.

1975-01-01

Quite often, complex structural components are idealised as beams in engineering analysis and design. Also, equations governing the responses of shallow shells are mathematically equivalent to the equations governing the responses of beams on elastic foundations. Hence with possible applications in several technical disciplines, the behaviour of beams on elastic foundations subjected to impact loads is studied in detail in the present investigation both analytically and experimentally. The analytical methods include analysis and energy method. The effect of foundation parameters (stiffness, and damping constants) on the dynamic responses of the beam-foundation system has been analysed. In modal analysis, the free-vibration equation has been solved by replacing the applied impulse by suitable initial conditions and the solution has been obtained as the linear combination of an infinite sequence of discrete eigen-vectors. In the energy method, the beam-foundation system is treated to be under forced vibrations and the forcing function has been obtained using the Hertz's law of impact. In the case of free-free end conditions of the beam, the rigid body modes and the elastic modes have been superposed to obtain the total response. The responses predicted using modal analysis are higher than those obtained using energy method. From the present study it is observed that model analysis is preferable to energy method. (Auth.)

Infinitely connected subgraphs in graphs of uncountable chromatic number

DEFF Research Database (Denmark)

Thomassen, Carsten

2016-01-01

Erdős and Hajnal conjectured in 1966 that every graph of uncountable chromatic number contains a subgraph of infinite connectivity. We prove that every graph of uncountable chromatic number has a subgraph which has uncountable chromatic number and infinite edge-connectivity. We also prove that......, if each orientation of a graph G has a vertex of infinite outdegree, then G contains an uncountable subgraph of infinite edge-connectivity....

A consistent formulation of wave propagation and conversion in low aspect ratio tokamaks with non-circular cross section

International Nuclear Information System (INIS)

Cuperman, S.; Bruma, C.; Komoshvili, K.

1999-01-01

The authors developed a consistent formalism for the full wave equation, appropriate for the study of propagation, absorption and wave conversion of externally launched waves in strongly toroidal, spherical tokamaks with non-circular cross-section. This includes also the formulation of rigorous regularity, boundary, gauge and periodicity conditions suitable for the exact solution of the wave equation for such devices

Automated Assume-Guarantee Reasoning for Omega-Regular Systems and Specifications

Science.gov (United States)

Chaki, Sagar; Gurfinkel, Arie

2010-01-01

We develop a learning-based automated Assume-Guarantee (AG) reasoning framework for verifying omega-regular properties of concurrent systems. We study the applicability of non-circular (AGNC) and circular (AG-C) AG proof rules in the context of systems with infinite behaviors. In particular, we show that AG-NC is incomplete when assumptions are restricted to strictly infinite behaviors, while AG-C remains complete. We present a general formalization, called LAG, of the learning based automated AG paradigm. We show how existing approaches for automated AG reasoning are special instances of LAG.We develop two learning algorithms for a class of systems, called infinite regular systems, that combine finite and infinite behaviors. We show that for infinity-regular systems, both AG-NC and AG-C are sound and complete. Finally, we show how to instantiate LAG to do automated AG reasoning for infinite regular, and omega-regular, systems using both AG-NC and AG-C as proof rules

On the Infinite Loch Ness monster

OpenAIRE

Arredondo, John A.; Maluendas, Camilo Ramírez

2017-01-01

In this paper we present in a topological way the construction of the orientable surface with only one end and infinite genus, called \\emph{The Infinite Loch Ness Monster}. In fact, we introduce a flat and hyperbolic construction of this surface. We discuss how the name of this surface has evolved and how it has been historically understood.

Role of interstitial atoms in the microstructure and non-linear elastic deformation behavior of Ti–Nb alloy

Energy Technology Data Exchange (ETDEWEB)

Tahara, Masaki [Division of Materials Science, University of Tsukuba, Tsukuba, Ibaraki 305-8573 (Japan); Precision and Intelligence Laboratory, Tokyo Institute of Technology, Yokohama 226-8503 (Japan); Kim, Hee Young, E-mail: heeykim@ims.tsukuba.ac.jp [Division of Materials Science, University of Tsukuba, Tsukuba, Ibaraki 305-8573 (Japan); Inamura, Tomonari; Hosoda, Hideki [Precision and Intelligence Laboratory, Tokyo Institute of Technology, Yokohama 226-8503 (Japan); Miyazaki, Shuichi, E-mail: miyazaki@ims.tsukuba.ac.jp [Division of Materials Science, University of Tsukuba, Tsukuba, Ibaraki 305-8573 (Japan); Center of Excellence for Advanced Materials Research, King Abdulaziz University, P.O. Box 80203, Jeddah 21589 (Saudi Arabia); School of Materials Science and Engineering and ERI, Gyeongsang National University, 900 Gazwadong, Jinju, Gyeongnam 660-701 (Korea, Republic of)

2013-11-15

Highlights: ► {110}{sub β}〈11{sup ¯}0〉{sub β} transverse type lattice modulation is confirmed in β phase. ► Nanosized modulated region (nanodomain) distributes homogeneously and randomly. ► Nanodomains act as obstacles against the long-ranged martensitic transformation. ► The origin of non-linear elastic deformation behavior is the continuous increase in lattice distortion strain of the favorable nanodomain variant during tensile deformation. -- Abstract: In order to clarify the effect of interstitial atoms on the non-linear elastic deformation behavior of the Ti–Nb alloy, the microstructure of (Ti–26Nb)–1.0O alloy was closely investigated by transmission electron microscope (TEM) and in situ X-ray diffraction (XRD) measurements. The 〈1 1 0〉{sub β}* rel rods and {1 1 1}{sub β}* rel planes were observed in a reciprocal space for the (Ti–26Nb)–1.0O alloy. Their origin was {110}{sub β}〈11{sup ¯}0〉{sub β} transverse type lattice modulation generated by oxygen atoms. Nanosized modulated domain structure (nanodomain) distributed homogeneously and randomly in the β phase and acted as obstacles for the long-ranged martensitic transformation in the (Ti–26Nb)–1.0O alloy. The non-linear elastic strain of the (Ti–26Nb)–1.0O alloy was generated by the continuous increase in lattice distortion strain of the favorable nanodomain variant during tensile deformation.

Role of interstitial atoms in the microstructure and non-linear elastic deformation behavior of Ti–Nb alloy

International Nuclear Information System (INIS)

Tahara, Masaki; Kim, Hee Young; Inamura, Tomonari; Hosoda, Hideki; Miyazaki, Shuichi

2013-01-01

Highlights: ► {110} β 〈11 ¯ 0〉 β transverse type lattice modulation is confirmed in β phase. ► Nanosized modulated region (nanodomain) distributes homogeneously and randomly. ► Nanodomains act as obstacles against the long-ranged martensitic transformation. ► The origin of non-linear elastic deformation behavior is the continuous increase in lattice distortion strain of the favorable nanodomain variant during tensile deformation. -- Abstract: In order to clarify the effect of interstitial atoms on the non-linear elastic deformation behavior of the Ti–Nb alloy, the microstructure of (Ti–26Nb)–1.0O alloy was closely investigated by transmission electron microscope (TEM) and in situ X-ray diffraction (XRD) measurements. The 〈1 1 0〉 β * rel rods and {1 1 1} β * rel planes were observed in a reciprocal space for the (Ti–26Nb)–1.0O alloy. Their origin was {110} β 〈11 ¯ 0〉 β transverse type lattice modulation generated by oxygen atoms. Nanosized modulated domain structure (nanodomain) distributed homogeneously and randomly in the β phase and acted as obstacles for the long-ranged martensitic transformation in the (Ti–26Nb)–1.0O alloy. The non-linear elastic strain of the (Ti–26Nb)–1.0O alloy was generated by the continuous increase in lattice distortion strain of the favorable nanodomain variant during tensile deformation

An integral equation method for the homogenization of unidirectional fibre-reinforced media; antiplane elasticity and other potential problems.

Science.gov (United States)

Joyce, Duncan; Parnell, William J; Assier, Raphaël C; Abrahams, I David

2017-05-01

In Parnell & Abrahams (2008 Proc. R. Soc. A 464 , 1461-1482. (doi:10.1098/rspa.2007.0254)), a homogenization scheme was developed that gave rise to explicit forms for the effective antiplane shear moduli of a periodic unidirectional fibre-reinforced medium where fibres have non-circular cross section. The explicit expressions are rational functions in the volume fraction. In that scheme, a (non-dilute) approximation was invoked to determine leading-order expressions. Agreement with existing methods was shown to be good except at very high volume fractions. Here, the theory is extended in order to determine higher-order terms in the expansion. Explicit expressions for effective properties can be derived for fibres with non-circular cross section, without recourse to numerical methods. Terms appearing in the expressions are identified as being associated with the lattice geometry of the periodic fibre distribution, fibre cross-sectional shape and host/fibre material properties. Results are derived in the context of antiplane elasticity but the analogy with the potential problem illustrates the broad applicability of the method to, e.g. thermal, electrostatic and magnetostatic problems. The efficacy of the scheme is illustrated by comparison with the well-established method of asymptotic homogenization where for fibres of general cross section, the associated cell problem must be solved by some computational scheme.

New applications of a generalized Hooke’s law for second gradient materials

Directory of Open Access Journals (Sweden)

K. Enakoutsa

2015-05-01

Full Text Available We provide analytical solutions to the problems of a circular bending of a beam in plane strain and the torsion of a non-circular cross-section beam, the beams obeying a second-gradient elasticity law proposed by the author, following a previous suggestion of Dell’Isola et al. (2009. The motivation was to find benchmark analytical solutions that can serve to grasp the physical foundations of second gradient elasticity laws for heterogeneous materials. The analytical solution of the circular beam problem presents the additional advantage to establish some nice properties on the unknown second gradient elastic moduli introduced by Enakoutsa (2014 model and the classical elasticity constants for both incompressible and compressible heterogeneous elastic materials. A framework to find the elastic moduli of the new model is also proposed.

INDUCTION HEATING OF NON-MAGNETIC SHEET METALS IN THE FIELD OF A FLAT CIRCULAR MULTITURN SOLENOID

Directory of Open Access Journals (Sweden)

Y. Batygin

2016-06-01

Full Text Available The theoretical analysis of electromagnetic processes in the system for induction heating presented by a flat circular multiturn solenoid positioned above a plane of thin sheet non-magnetic metal has been conducted. The calculated dependences for the current induced in a metal sheet blank and ratio of transformation determined have been obtained. The maximal value of the transformation ratio with regard to spreading the eddy-currents over the whole area of the sheet metal has been determined.

Bulk solitary waves in elastic solids

Science.gov (United States)

Samsonov, A. M.; Dreiden, G. V.; Semenova, I. V.; Shvartz, A. G.

2015-10-01

A short and object oriented conspectus of bulk solitary wave theory, numerical simulations and real experiments in condensed matter is given. Upon a brief description of the soliton history and development we focus on bulk solitary waves of strain, also known as waves of density and, sometimes, as elastic and/or acoustic solitons. We consider the problem of nonlinear bulk wave generation and detection in basic structural elements, rods, plates and shells, that are exhaustively studied and widely used in physics and engineering. However, it is mostly valid for linear elasticity, whereas dynamic nonlinear theory of these elements is still far from being completed. In order to show how the nonlinear waves can be used in various applications, we studied the solitary elastic wave propagation along lengthy wave guides, and remarkably small attenuation of elastic solitons was proven in physical experiments. Both theory and generation for strain soliton in a shell, however, remained unsolved problems until recently, and we consider in more details the nonlinear bulk wave propagation in a shell. We studied an axially symmetric deformation of an infinite nonlinearly elastic cylindrical shell without torsion. The problem for bulk longitudinal waves is shown to be reducible to the one equation, if a relation between transversal displacement and the longitudinal strain is found. It is found that both the 1+1D and even the 1+2D problems for long travelling waves in nonlinear solids can be reduced to the Weierstrass equation for elliptic functions, which provide the solitary wave solutions as appropriate limits. We show that the accuracy in the boundary conditions on free lateral surfaces is of crucial importance for solution, derive the only equation for longitudinal nonlinear strain wave and show, that the equation has, amongst others, a bidirectional solitary wave solution, which lead us to successful physical experiments. We observed first the compression solitary wave in the

High-pressure crystal structure of elastically isotropic CaTiO3 perovskite under hydrostatic and non-hydrostatic conditions.

Science.gov (United States)

Zhao, Jing; Ross, Nancy L; Wang, Di; Angel, Ross J

2011-11-16

The structural evolution of orthorhombic CaTiO3 perovskite has been studied using high-pressure single-crystal x-ray diffraction under hydrostatic conditions up to 8.1 GPa and under a non-hydrostatic stress field formed in a diamond anvil cell (DAC) up to 4.7 GPa. Under hydrostatic conditions, the TiO6 octahedra become more tilted and distorted with increasing pressure, similar to other 2:4 perovskites. Under non-hydrostatic conditions, the experiments do not show any apparent difference in the internal structural variation from hydrostatic conditions and no additional tilts and distortions in the TiO6 octahedra are observed, even though the lattice itself becomes distorted due to the non-hydrostatic stress. The similarity between the hydrostatic and non-hydrostatic cases can be ascribed to the fact that CaTiO3 perovskite is nearly elastically isotropic and, as a consequence, its deviatoric unit-cell volume strain produced by the non-hydrostatic stress is very small; in other words, the additional octahedral tilts relevant to the extra unit-cell volume associated with the deviatoric unit-cell volume strain may be totally neglected. This study further addresses the role that three factors--the elastic properties, the crystal orientation and the pressure medium--have on the structural evolution of an orthorhombic perovskite loaded in a DAC under non-hydrostatic conditions. The influence of these factors can be clearly visualized by plotting the three-dimensional distribution of the deviatoric unit-cell volume strain in relation to the cylindrical axis of the DAC and indicates that, if the elasticity of a perovskite is nearly isotropic as it is for CaTiO3, the other two factors become relatively insignificant.

High-pressure crystal structure of elastically isotropic CaTiO3 perovskite under hydrostatic and non-hydrostatic conditions

International Nuclear Information System (INIS)

Zhao Jing; Ross, Nancy L; Wang, Di; Angel, Ross J

2011-01-01

The structural evolution of orthorhombic CaTiO 3 perovskite has been studied using high-pressure single-crystal x-ray diffraction under hydrostatic conditions up to 8.1 GPa and under a non-hydrostatic stress field formed in a diamond anvil cell (DAC) up to 4.7 GPa. Under hydrostatic conditions, the TiO 6 octahedra become more tilted and distorted with increasing pressure, similar to other 2:4 perovskites. Under non-hydrostatic conditions, the experiments do not show any apparent difference in the internal structural variation from hydrostatic conditions and no additional tilts and distortions in the TiO 6 octahedra are observed, even though the lattice itself becomes distorted due to the non-hydrostatic stress. The similarity between the hydrostatic and non-hydrostatic cases can be ascribed to the fact that CaTiO 3 perovskite is nearly elastically isotropic and, as a consequence, its deviatoric unit-cell volume strain produced by the non-hydrostatic stress is very small; in other words, the additional octahedral tilts relevant to the extra unit-cell volume associated with the deviatoric unit-cell volume strain may be totally neglected. This study further addresses the role that three factors-the elastic properties, the crystal orientation and the pressure medium-have on the structural evolution of an orthorhombic perovskite loaded in a DAC under non-hydrostatic conditions. The influence of these factors can be clearly visualized by plotting the three-dimensional distribution of the deviatoric unit-cell volume strain in relation to the cylindrical axis of the DAC and indicates that, if the elasticity of a perovskite is nearly isotropic as it is for CaTiO 3 , the other two factors become relatively insignificant. (paper)

Finite plate thickness effects on the Rayleigh-Taylor instability in elastic-plastic materials

Science.gov (United States)

Polavarapu, Rinosh; Banerjee, Arindam

2017-11-01

The majority of theoretical studies have tackled the Rayleigh-Taylor instability (RTI) problem in solids using an infinitely thick plate. Recent theoretical studies by Piriz et al. (PRE 95, 053108, 2017) have explored finite thickness effects. We seek to validate this recent theoretical estimate experimentally using our rotating wheel RTI experiment in an accelerated elastic-plastic material. The test section consists of a container filled with air and mayonnaise (a non-Newtonian emulsion) with an initial perturbation between two materials. The plate thickness effects are studied by varying the depth of the soft-solid. A set of experiments is run by employing different initial conditions with different container dimensions. Additionally, the effect of acceleration rate (driving pressure rise time) on the instability threshold with reference to the finite thickness will also be inspected. Furthermore, the experimental results are compared to the analytical strength models related to finite thickness effects on RTI. Authors acknowledge financial support from DOE-SSAA Grant # DE-NA0003195 and LANL subcontract #370333.

Circular Solutions

NARCIS (Netherlands)

Annevelink, E.; Bos, H.L.; Meesters, K.P.H.; Oever, van den M.J.A.; Haas, de W.; Kuikman, P.J.; Rietra, R.P.J.J.; Sikirica, N.

2016-01-01

The fifth part of this report on Circular Solutions is about the circular principle From Waste to Resource. The purpose of this study is to select promising options for the implementation of this circular principle and to elaborate these options further.

Dynamical entropy for infinite quantum systems

International Nuclear Information System (INIS)

Hudetz, T.

1990-01-01

We review the recent physical application of the so-called Connes-Narnhofer-Thirring entropy, which is the successful quantum mechanical generalization of the classical Kolmogorov-Sinai entropy and, by its very conception, is a dynamical entropy for infinite quantum systems. We thus comparingly review also the physical applications of the classical dynamical entropy for infinite classical systems. 41 refs. (Author)

Necessary and Sufficient Conditions for Pareto Optimality in Infinite Horizon Cooperative Differential Games

NARCIS (Netherlands)

Reddy, P.V.; Engwerda, J.C.

2011-01-01

In this article we derive necessary and sufficient conditions for the existence of Pareto optimal solutions for infinite horizon cooperative differential games. We consider games defined by non autonomous and discounted autonomous systems. The obtained results are used to analyze the regular

Use of customised pressure-guided elastic bandages to improve efficacy of compression bandaging for venous ulcers.

Science.gov (United States)

Sermsathanasawadi, Nuttawut; Chatjaturapat, Choedpong; Pianchareonsin, Rattana; Puangpunngam, Nattawut; Wongwanit, Chumpol; Chinsakchai, Khamin; Ruangsetakit, Chanean; Mutirangura, Pramook

2017-08-01

Compression bandaging is a major treatment of chronic venous ulcers. Its efficacy depends on the applied pressure, which is dependent on the skill of the individual applying the bandage. To improve the quality of bandaging by reducing the variability in compression bandage interface pressures, we changed elastic bandages into a customised version by marking them with circular ink stamps, applied when the stretch achieves an interface pressure between 35 and 45 mmHg. Repeated applications by 20 residents of the customised bandage and non-marked bandage to one smaller and one larger leg were evaluated by measuring the sub-bandage pressure. The results demonstrated that the target pressure range is more often attained with the customised bandage compared with the non-marked bandage. The customised bandage improved the efficacy of compression bandaging for venous ulcers, with optimal sub-bandage pressure. © 2016 Medicalhelplines.com Inc and John Wiley & Sons Ltd.

Transient Vibrations of an Elastic Cylinder Inserted in the Elastic Medium

Directory of Open Access Journals (Sweden)

Sulym Heorgij

2016-06-01

Full Text Available Using method of Laguerre polynomials we have obtained the solution of the dynamic problem of the theory of elasticity for elastic cylinder inserted into massive body modeled as a space. The source of non-stationary processes in composite is high intensity force load of the inner surface of the cylinder. On the surface separation of materials of space and cylinder the conditions of ideal mechanical contact are satisfied. The solution is obtained as series of Laguerre polynomials, which coefficients are found from recurrent relations. The results of numerical analysis of transient stress-strain state in elastic space with cylindrical insertion might be used for the technological process of hydraulic fracturing during shale gas extraction.

Degrees of infinite words, polynomials and atoms

NARCIS (Netherlands)

J. Endrullis; J. Karhumaki; J.W. Klop (Jan Willem); A. Saarela

2016-01-01

textabstractOur objects of study are finite state transducers and their power for transforming infinite words. Infinite sequences of symbols are of paramount importance in a wide range of fields, from formal languages to pure mathematics and physics. While finite automata for recognising and

Degrees of infinite words, polynomials and atoms

NARCIS (Netherlands)

Endrullis, Jörg; Karhumäki, Juhani; Klop, Jan Willem; Saarela, Aleksi

2016-01-01

Our objects of study are finite state transducers and their power for transforming infinite words. Infinite sequences of symbols are of paramount importance in a wide range of fields, from formal languages to pure mathematics and physics. While finite automata for recognising and transforming

Lyapunov exponents for infinite dimensional dynamical systems

Science.gov (United States)

Mhuiris, Nessan Mac Giolla

1987-01-01

Classically it was held that solutions to deterministic partial differential equations (i.e., ones with smooth coefficients and boundary data) could become random only through one mechanism, namely by the activation of more and more of the infinite number of degrees of freedom that are available to such a system. It is only recently that researchers have come to suspect that many infinite dimensional nonlinear systems may in fact possess finite dimensional chaotic attractors. Lyapunov exponents provide a tool for probing the nature of these attractors. This paper examines how these exponents might be measured for infinite dimensional systems.

Quantum control in infinite dimensions

International Nuclear Information System (INIS)

Karwowski, Witold; Vilela Mendes, R.

2004-01-01

Accurate control of quantum evolution is an essential requirement for quantum state engineering, laser chemistry, quantum information and quantum computing. Conditions of controllability for systems with a finite number of energy levels have been extensively studied. By contrast, results for controllability in infinite dimensions have been mostly negative, stating that full control cannot be achieved with a finite-dimensional control Lie algebra. Here we show that by adding a discrete operation to a Lie algebra it is possible to obtain full control in infinite dimensions with a small number of control operators

Analysis of Elastic-Plastic J Integrals for 3-Dimensional Cracks Using Finite Element Alternating Method

International Nuclear Information System (INIS)

Park, Jai Hak

2009-01-01

SGBEM(Symmetric Galerkin Boundary Element Method)-FEM alternating method has been proposed by Nikishkov, Park and Atluri. In the proposed method, arbitrarily shaped three-dimensional crack problems can be solved by alternating between the crack solution in an infinite body and the finite element solution without a crack. In the previous study, the SGBEM-FEM alternating method was extended further in order to solve elastic-plastic crack problems and to obtain elastic-plastic stress fields. For the elastic-plastic analysis the algorithm developed by Nikishkov et al. is used after modification. In the algorithm, the initial stress method is used to obtain elastic-plastic stress and strain fields. In this paper, elastic-plastic J integrals for three-dimensional cracks are obtained using the method. For that purpose, accurate values of displacement gradients and stresses are necessary on an integration path. In order to improve the accuracy of stress near crack surfaces, coordinate transformation and partitioning of integration domain are used. The coordinate transformation produces a transformation Jacobian, which cancels the singularity of the integrand. Using the developed program, simple three-dimensional crack problems are solved and elastic and elastic-plastic J integrals are obtained. The obtained J integrals are compared with the values obtained using a handbook solution. It is noted that J integrals obtained from the alternating method are close to the values from the handbook

Operational circular No. 1 (Rev. 1) – Operational circulars

CERN Multimedia

HR Department

2011-01-01

Operational Circular No. 1 (Rev. 1) is applicable to members of the personnel and other persons concerned. Operational Circular No. 1 (Rev. 1) entitled "Operational circulars", approved following discussion at the Standing Concertation Committee meeting on 4 May 2011, is available on the intranet site of the Human Resources Department: https://hr-docs.web.cern.ch/hr-docs/opcirc/opcirc.asp It cancels and replaces Operational Circular No. 1 entitled "Operational Circulars” of December 1996. This new version clarifies, in particular, that operational circulars do not necessarily arise from the Staff Rules and Regulations, and the functional titles have been updated to bring them into line with the current CERN organigram. Department Head Office  

Surface green function matching for a three-dimensional non-local continuum

International Nuclear Information System (INIS)

Idiodi, J.O.A.

1985-07-01

With a view toward helping to bridge the gap, from the continuum side, between discrete and continuum models of crystalline, elastic solids, explicit results are presented for non-local stress tensors that describe exactly some lattice dynamical models that have been widely used in the literature for cubic lattices. The Surface Green Function Matching (SGFM) method, which has been used successfully for a variety of surface problems, is then extended, within a continuum approach, to a non-local continuum that models a three-dimensional discrete lattice. The practical use of the method is demonstrated by performing a fairly complete analytical study of the vibrational surface modes of the SCC semi-infinite medium. Some results are presented for the [100] direction of the (001) surface of the SCC lattice. (author)

The exp-normal distribution is infinitely divisible

OpenAIRE

Pinelis, Iosif

2018-01-01

Let $Z$ be a standard normal random variable (r.v.). It is shown that the distribution of the r.v. $\\ln|Z|$ is infinitely divisible; equivalently, the standard normal distribution considered as the distribution on the multiplicative group over $\\mathbb{R}\\setminus\\{0\\}$ is infinitely divisible.

Infinite Dimensional Differential Games with Hybrid Controls

Indian Academy of Sciences (India)

... zero-sum infinite dimensional differential game of infinite duration with discounted payoff involving hybrid controls is studied. The minimizing player is allowed to take continuous, switching and impulse controls whereas the maximizing player is allowed to take continuous and switching controls. By taking strategies in the ...

R -Dimensional ESPRIT-Type Algorithms for Strictly Second-Order Non-Circular Sources and Their Performance Analysis

Science.gov (United States)

Steinwandt, Jens; Roemer, Florian; Haardt, Martin; Galdo, Giovanni Del

2014-09-01

High-resolution parameter estimation algorithms designed to exploit the prior knowledge about incident signals from strictly second-order (SO) non-circular (NC) sources allow for a lower estimation error and can resolve twice as many sources. In this paper, we derive the R-D NC Standard ESPRIT and the R-D NC Unitary ESPRIT algorithms that provide a significantly better performance compared to their original versions for arbitrary source signals. They are applicable to shift-invariant R-D antenna arrays and do not require a centrosymmetric array structure. Moreover, we present a first-order asymptotic performance analysis of the proposed algorithms, which is based on the error in the signal subspace estimate arising from the noise perturbation. The derived expressions for the resulting parameter estimation error are explicit in the noise realizations and asymptotic in the effective signal-to-noise ratio (SNR), i.e., the results become exact for either high SNRs or a large sample size. We also provide mean squared error (MSE) expressions, where only the assumptions of a zero mean and finite SO moments of the noise are required, but no assumptions about its statistics are necessary. As a main result, we analytically prove that the asymptotic performance of both R-D NC ESPRIT-type algorithms is identical in the high effective SNR regime. Finally, a case study shows that no improvement from strictly non-circular sources can be achieved in the special case of a single source.

Using PWE/FE method to calculate the band structures of the semi-infinite beam-like PCs: Periodic in z-direction and finite in x–y plane

Energy Technology Data Exchange (ETDEWEB)

Qian, Denghui, E-mail: qdhsd318@163.com; Shi, Zhiyu, E-mail: zyshi@nuaa.edu.cn

2017-05-03

This paper couples the plane wave expansion (PWE) and finite element (FE) methods to calculate the band structures of the semi-infinite beam-like phononic crystals (PCs) with the infinite periodicity in z-direction and finiteness in x–y plane. Explicit matrix formulations are developed for the calculation of band structures. In order to illustrate the applicability and accuracy of the proposed coupled plane wave expansion and finite element (PWE/FE) method to beam-like PCs, several examples are displayed. At first, PWE/FE method is applied to calculate the band structures of the Pb/rubber beam-like PCs with circular and rectangular cross sections, respectively. Then, it is used to calculate the band structures of steel/epoxy and steel/aluminum beam-like PCs with the same geometric parameters. Last, the band structure of the three-component beam-like PC is also calculated by the proposed method. Moreover, all the results calculated by PWE/FE method are compared with those calculated by finite element (FE) method, and the corresponding results are in good agreement. - Highlights: • The concept of the semi-infinite beam-like phononic crystals (PCs) is proposed. • The PWE/FE method is proposed and formulized to calculate the band structures of the semi-infinite beam-like PCs. • The strong applicability and high accuracy of PWE/FE method are verified.

Wave chaos in the elastic disk.

Science.gov (United States)

Sondergaard, Niels; Tanner, Gregor

2002-12-01

The relation between the elastic wave equation for plane, isotropic bodies and an underlying classical ray dynamics is investigated. We study, in particular, the eigenfrequencies of an elastic disk with free boundaries and their connection to periodic rays inside the circular domain. Even though the problem is separable, wave mixing between the shear and pressure component of the wave field at the boundary leads to an effective stochastic part in the ray dynamics. This introduces phenomena typically associated with classical chaos as, for example, an exponential increase in the number of periodic orbits. Classically, the problem can be decomposed into an integrable part and a simple binary Markov process. Similarly, the wave equation can, in the high-frequency limit, be mapped onto a quantum graph. Implications of this result for the level statistics are discussed. Furthermore, a periodic trace formula is derived from the scattering matrix based on the inside-outside duality between eigenmodes and scattering solutions and periodic orbits are identified by Fourier transforming the spectral density.

Buckling of a stiff thin film on an elastic graded compliant substrate

Science.gov (United States)

Chen, Zhou; Chen, Weiqiu; Song, Jizhou

2017-12-01

The buckling of a stiff film on a compliant substrate has attracted much attention due to its wide applications such as thin-film metrology, surface patterning and stretchable electronics. An analytical model is established for the buckling of a stiff thin film on a semi-infinite elastic graded compliant substrate subjected to in-plane compression. The critical compressive strain and buckling wavelength for the sinusoidal mode are obtained analytically for the case with the substrate modulus decaying exponentially. The rigorous finite element analysis (FEA) is performed to validate the analytical model and investigate the postbuckling behaviour of the system. The critical buckling strain for the period-doubling mode is obtained numerically. The influences of various material parameters on the results are investigated. These results are helpful to provide physical insights on the buckling of elastic graded substrate-supported thin film.

Calibration of circular aperture area using vision probe at inmetro

Directory of Open Access Journals (Sweden)

Costa Pedro Bastos

2016-01-01

Full Text Available Circular aperture areas are standards of high importance for the realization of photometric and radiometric measurements, where the accuracy of these measures is related to the accuracy of the circular aperture area calibrations. In order to attend the requirement for traceability was developed in Brazilian metrology institute, a methodology for circular aperture area measurement as requirements from the radiometric and photometric measurements. In the developed methodology apertures are measured by non-contact measurement through images of the aperture edges captured by a camera. These images are processed using computer vision techniques and then the values of the circular aperture area are determined.

Circularly polarized luminescence of syndiotactic polystyrene

Science.gov (United States)

Rizzo, Paola; Abbate, Sergio; Longhi, Giovanna; Guerra, Gaetano

2017-11-01

Syndiotactic polystyrene (s-PS) films, when crystallized from the amorphous state by temporary sorption of non-racemic guest molecules (like carvone) not only exhibit unusually high optical activity, both in the UV-Visible and Infrared ranges, but also present circularly polarized luminescence (CPL) with high dissymmetry ratios (g = ΔI/I values in the range 0.02-0.03). Experimental evidences provide support, rather than to the usual molecular circular dichroism, to a supramolecular chiral optical response being extrinsic to the site of photon absorption and emission, possibly associated with a helical morphology of s-PS crystallites.

A New Theory of Non-Linear Thermo-Elastic Constitutive Equation of Isotropic Hyperelastic Materials

Science.gov (United States)

Li, Chen; Liao, Yufei

2018-03-01

Considering the influence of temperature and strain variables on materials. According to the relationship of conjugate stress-strain, a complete and irreducible non-linear constitutive equation of isotropic hyperelastic materials is derived and the constitutive equations of 16 types of isotropic hyperelastic materials are given we study the transformation methods and routes of 16 kinds of constitutive equations and the study proves that transformation of two forms of constitutive equation. As an example of application, the non-linear thermo-elastic constitutive equation of isotropic hyperelastic materials is combined with the natural vulcanized rubber experimental data in the existing literature base on MATLAB, The results show that the fitting accuracy is satisfactory.

A High-Order Theory for the Analysis of Circular Cylindrical Composite Sandwich Shells with Transversely Compliant Core Subjected to External Loads

DEFF Research Database (Denmark)

Rahmani, Omid; Khalili, S.M.R.; Thomsen, Ole Thybo

2012-01-01

A new model based on the high order sandwich panel theory is proposed to study the effect of external loads on the free vibration of circular cylindrical composite sandwich shells with transversely compliant core, including also the calculation of the buckling loads. In the present model......, which is based on a 3D elasticity solution for the core material, can be used as a benchmark in future studies of the free vibration and buckling of circular cylindrical composite sandwich shells with a transversely compliant core....

Ultrasound Shear Wave Simulation of Breast Tumor Using Nonlinear Tissue Elasticity

Directory of Open Access Journals (Sweden)

Dae Woo Park

2016-01-01

Full Text Available Shear wave elasticity imaging (SWEI can assess the elasticity of tissues, but the shear modulus estimated in SWEI is often less sensitive to a subtle change of the stiffness that produces only small mechanical contrast to the background tissues. Because most soft tissues exhibit mechanical nonlinearity that differs in tissue types, mechanical contrast can be enhanced if the tissues are compressed. In this study, a finite element- (FE- based simulation was performed for a breast tissue model, which consists of a circular (D: 10 mm, hard tumor and surrounding tissue (soft. The SWEI was performed with 0% to 30% compression of the breast tissue model. The shear modulus of the tumor exhibited noticeably high nonlinearity compared to soft background tissue above 10% overall applied compression. As a result, the elastic modulus contrast of the tumor to the surrounding tissue was increased from 0.46 at 0% compression to 1.45 at 30% compression.

Ultrasound Shear Wave Simulation of Breast Tumor Using Nonlinear Tissue Elasticity.

Science.gov (United States)

Park, Dae Woo

2015-01-01

Shear wave elasticity imaging (SWEI) can assess the elasticity of tissues, but the shear modulus estimated in SWEI is often less sensitive to a subtle change of the stiffness that produces only small mechanical contrast to the background tissues. Because most soft tissues exhibit mechanical nonlinearity that differs in tissue types, mechanical contrast can be enhanced if the tissues are compressed. In this study, a finite element- (FE-) based simulation was performed for a breast tissue model, which consists of a circular (D: 10 mm, hard) tumor and surrounding tissue (soft). The SWEI was performed with 0% to 30% compression of the breast tissue model. The shear modulus of the tumor exhibited noticeably high nonlinearity compared to soft background tissue above 10% overall applied compression. As a result, the elastic modulus contrast of the tumor to the surrounding tissue was increased from 0.46 at 0% compression to 1.45 at 30% compression.

Elevated-temperature tests of simply-supported beams and circular plates subjected to time-varying loadings

International Nuclear Information System (INIS)

Corum, J.M.; Richardson, M.

1975-01-01

The measured elastic-plastic and elastic-plastic-creep responses of a number of simply-supported type 304 stainless steel beams and circular plates are presented. Beams and plates exhibit the essential features of inelastic structural behavior; yet they are relatively simple. In beams, the stress fields are largely uniaxial, while multiaxial effects are introduced in plates. The specimens were laterally loaded at the center, and the tests were performed by subjecting the specimens to either a prescribed load or center-deflection history. The specimens were machined from a common, well-characterized heat of material, and all of the tests were performed at a temperature of 1100 F. The elastic-plastic tests consisted of short-time cycling of the center load, or deflection, between fixed limits. In the elastic-plastic-creep tests the center load, or deflection, was held constant for periods of time, but was periodically subjected to a step increase or decrease, including reversals. The test results are presented in terms of the load and center-deflection behaviors, which typify the overall structural behavior. (U.S.)

Theories for Elastic Plates via Orthogonal Polynomials

DEFF Research Database (Denmark)

Krenk, Steen

1981-01-01

A complementary energy functional is used to derive an infinite system of two-dimensional differential equations and appropriate boundary conditions for stresses and displacements in homogeneous anisotropic elastic plates. Stress boundary conditions are imposed on the faces a priori......, and this introduces a weight function in the variations of the transverse normal and shear stresses. As a result the coupling between the two-dimensional differential equations is described in terms of a single difference operator. Special attention is given to a truncated system of equations for bending...... of transversely isotropic plates. This theory has three boundary conditions, like Reissner's, but includes the effect of transverse normal strain, essentially through a reinterpretation of the transverse displacement function. Full agreement with general integrals to the homogeneous three-dimensional equations...

Understanding the Behaviour of Infinite Ladder Circuits

Science.gov (United States)

Ucak, C.; Yegin, K.

2008-01-01

Infinite ladder circuits are often encountered in undergraduate electrical engineering and physics curricula when dealing with series and parallel combination of impedances, as a part of filter design or wave propagation on transmission lines. The input impedance of such infinite ladder circuits is derived by assuming that the input impedance does…

Infinite periodic minimal surfaces and their crystallography in the hyperbolic plane

International Nuclear Information System (INIS)

Sadoc, J.F.; Charvolin, J.

1989-01-01

Infinite periodic minimal surfaces are now being introduced to describe some complex structures with large cells, formed by inorganic and organic materials, which can be considered as crystals of surfaces or films. Among them are the spectacular cubic crystalline structures built by amphiphilic molecules in the presence of water. The crystallographic properties of these surfaces are studied from an intrinsic point of view, using operations of groups of symmetry defined by displacements on their surface. This approach takes advantage of the relation existing between these groups and those characterizing the tilings of the hyperbolic plane. First, the general bases of the particular crystallography of the hyperbolic plane are presented. Then the translation subgroups of the hyperbolic plane are determined in one particular case, that of the tiling involved in the problem of cubic structures of liquid crystals. Finally, it is shown that the infinite periodic minimal surfaces used to describe these structures can be obtained from the hyperbolic plane when some translations are forced to identity. This is indeed formally analogous to the simple process of transformation of a Euclidean plane into a cylinder, when a translation of the plane is forced to identity by rolling the plane onto itself. Thus, this approach transforms the 3D problem of infinite periodic minimal surfaces into a 2D problem and, although the latter is to be treated in a non-Euclidean space, provides a relatively simple formalism for the investigation of infinite periodic surfaces in general and the study of the geometrical transformations relating them. (orig.)

User's guide for SLWDN9, a code for calculating flux-surfaced-averaging of alpha densities, currents, and heating in non-circular tokamaks

International Nuclear Information System (INIS)

Hively, L.M.; Miley, G.M.

1980-03-01

The code calculates flux-surfaced-averaged values of alpha density, current, and electron/ion heating profiles in realistic, non-circular tokamak plasmas. The code is written in FORTRAN and execute on the CRAY-1 machine at the Magnetic Fusion Energy Computer Center

Infinite elements for soil-structure interaction analysis in multi-layered halfspaces

International Nuclear Information System (INIS)

Yun, Chung Bang; Kim, Jae Min; Yang, Shin Chu

1994-01-01

This paper presents the theoretical aspects of a computer code (KIESSI) for soil-structure interaction analysis in a multi-layered halfspace using infinite elements. The shape functions of the infinite elements are derived from approximate expressions of the analytical solutions. Three different infinite elements are developed. They are the horizontal, the vertical and the comer infinite elements (HIE, VIE and CIE). Numerical example analyses are presented for demonstrating the effectiveness of the proposed infinite elements

Scattering of a pulse by a cavity in an elastic half-space

International Nuclear Information System (INIS)

Scandrett, C.L.; Kriegsmann, G.A.; Achienbach, J.D.

1986-01-01

The finite difference technique is employed to study plane strain scattering of pulses from finite anomalies embedded in an isotropic, homogeneous, elastic half-space. In particular, the scatterer is taken to by a cylindrical cavity. A new transmission boundary condition is developed which transmits energy conveyed by Rayleigh surface waves. This condition is successfully employed in reducing the domain of numerical calculations from a semi-infinite to a finite region. A test of the numerical scheme is given by considering a time harmonic pulse of infinite extent. The numerical technique is marched out in time until transients have radiated away and a steady state solution has been reached which is found to be in good agreement with results produced by a series type solution. Time domain solutions are given in terms of time histories of displacements at the half-space free surface; and by sequences of snapshots, taken of the entire numerical domain, which illustrate the scattering dynamics

Quark ensembles with infinite correlation length

OpenAIRE

Molodtsov, S. V.; Zinovjev, G. M.

2014-01-01

By studying quark ensembles with infinite correlation length we formulate the quantum field theory model that, as we show, is exactly integrable and develops an instability of its standard vacuum ensemble (the Dirac sea). We argue such an instability is rooted in high ground state degeneracy (for 'realistic' space-time dimensions) featuring a fairly specific form of energy distribution, and with the cutoff parameter going to infinity this inherent energy distribution becomes infinitely narrow...

Non-Invasive Assessment of Hepatic Fibrosis by Elastic Measurement of Liver Using Magnetic Resonance Tagging Images

Directory of Open Access Journals (Sweden)

Xuejun Zhang

2018-03-01

Full Text Available To date, the measurement of the stiffness of liver requires a special vibrational tool that limits its application in many hospitals. In this study, we developed a novel method for automatically assessing the elasticity of the liver without any use of contrast agents or mechanical devices. By calculating the non-rigid deformation of the liver from magnetic resonance (MR tagging images, the stiffness was quantified as the displacement of grids on the liver image during a forced exhalation cycle. Our methods include two major processes: (1 quantification of the non-rigid deformation as the bending energy (BE based on the thin-plate spline method in the spatial domain and (2 calculation of the difference in the power spectrum from the tagging images, by using fast Fourier transform in the frequency domain. By considering 34 cases (17 normal and 17 abnormal liver cases, a remarkable difference between the two groups was found by both methods. The elasticity of the liver was finally analyzed by combining the bending energy and power spectral features obtained through MR tagging images. The result showed that only one abnormal case was misclassified in our dataset, which implied our method for non-invasive assessment of liver fibrosis has the potential to reduce the traditional liver biopsy.

Panels with low-Q-factor resonators with theoretically infinite sound-proofing ability at a single frequency

Science.gov (United States)

Lazarev, L. A.

2015-07-01

An infinite panel with two types of resonators regularly installed on it is theoretically considered. Each resonator is an air-filled cavity hermetically closed by a plate, which executes piston vibrations. The plate and air inside the cavity play the roles of mass and elasticity, respectively. Every other resonator is reversed. At a certain ratio between the parameters of the resonators at the tuning frequency of the entire system, the acoustic-pressure force that directly affects the panel can be fully compensated by the action forces of the resonators. In this case, the sound-proofing ability (transmission loss) tends to infinity. The presented calculations show that a complete transmission-loss effect can be achieved even with low- Q resonators.

Prevention of Bridge Scour with Non-uniform Circular Piers Plane under Steady Flows

Science.gov (United States)

Chen, Hsing-Ting; Wang, Chuan-Yi

2017-04-01

River bed scour and deposit variation extremely severe because of most of rivers are steep and rapid flows, and river discharge extremely unstable and highly unsteady during different seasons in Taiwan. In addition to the obstruction of piers foundation, it causes local scour and threatens the safety of bridges. In the past, riprap, wire gabion or wrap pier works were adopted as the protections of piers foundation, but there were no effectual outcomes. The events of break off piers still happen sometimes. For example, typhoon Kalmaegi (2008) and Morakot (2009) caused heavy damages on Ho-Fon bridge in the Da-jia river and Shuang-Yuan bridge in the Kao-Ping river, respectively. Accordingly, to understand the piers scour system and propose an appropriate protection of piers foundation becomes an important topic for this study currently. This research improves the protection works of the existing uniform bridge pier (diameter D) to ensure the safety of the bridge. The non-uniform plane of circular piers (diameter D*) are placed on the top of a bridge pier foundation to reduce the down flow impacting energy and scour by its' surface roughness characteristics. This study utilize hydraulic models to simulate local scour depth and scour depth change with time for non-uniform pier diameter ratio D/D* of 0.3,0.4,0.5,0.6,0.7 and 0.8, and different type pier and initial bed level (Y) relative under the foundation top elevation under steady flows of V/Vc=0.95,0.80 and 0.65. The research results show that the scour depth increases with an increase of flow intensity (V/Vc) under different types of steady flow hydrographs. The scour depth decreases with increase of initial bed level (Y=+0.2D*,0D*and -0.2D*) relative under the foundation top elevation of the different type pier. The maximum scour depth occurred in the front of the pier for all conditions. Because of the scouring retardation by the non-uniform plane of foundation, the scour depth is reduced for the un-exposed bridge

A connection between free and classical infinite divisibility

DEFF Research Database (Denmark)

Barndorff-Nielsen, Ole Eiler; Thorbjørnsen, Steen

2004-01-01

In this paper we continue our studies, initiated in Refs. 2–4, of the connections between the classes of infinitely divisible probability measures in classical and in free probability. We show that the free cumulant transform of any freely infinitely divisible probability measure equals...... the classical cumulant transform of a certain classically infinitely divisible probability measure, and we give several characterizations of the latter measure, including an interpretation in terms of stochastic integration. We find, furthermore, an alternative definition of the Bercovici–Pata bijection, which...

Administrative circular

CERN Multimedia

2003-01-01

• N° 21 - August 2003 Special leave This circular has been amended. Copies of this circular are available in the Divisional Secretariats. In addition, administrative and operational circulars, as well as the lists of those in force, are available for consultation on the Web at: http://cern.ch/hr-div/internal/admin_services/admincirc/listadmincirc.asp Human Resources Division Tel. 74128

The new electromagnetic tetrads, infinite tetrad nesting and the non-trivial emergence of complex numbers in real theories of gravitation

Science.gov (United States)

Garat, Alcides

How complex numbers get into play in a non-trivial way in real theories of gravitation is relevant since in a unified structure they should be able to relate in a natural way with quantum theories. For a long time this issue has been lingering on both relativistic formulations and quantum theories. We will analyze this fundamental subject under the light of new group isomorphism theorems linking local internal groups of transformations and local groups of spacetime transformations. The bridge between these two kinds of transformations is represented by new tetrads introduced previously. It is precisely through these local tetrad structures that we will provide a non-trivial answer to this old issue. These new tetrads have two fundamental building components, the skeletons and the gauge vectors. It is these constructive elements that provide the mathematical support that allows to prove group isomorphism theorems. In addition to this, we will prove a unique new property, the infinite tetrad nesting, alternating the nesting with non-Abelian tetrads in the construction of the tetrad gauge vectors. As an application we will demonstrate an alternative proof of a new group isomorphism theorem.

Administrative Circulars Rev.

CERN Multimedia

2003-01-01

Administrative Circular N° 19 (Rev. 3) - April 2003 Subsistence indemnity - Other expenses necessarily incurred in the course of duty travelAdministrative Circular N° 25 (Rev. 2) - April 2003 Shift work - Special provisions for the Fire and Rescue Service - These circulars have been revised. Human Resources Division Tel. 74128Copies of these circulars are available in the Divisional Secretariats. In addition, administrative and operational circulars, as well as the lists of those in force, are available for consultation on the Web at: http://humanresources.web.cern.ch/humanresources/internal/admin_services/admincirc/listadmincirc.asp

Semantic coherence in English accusative-with-bare-infinitive constructions

DEFF Research Database (Denmark)

Jensen, Kim Ebensgaard

2013-01-01

Drawing on usage-based cognitively oriented construction grammar, this paper investigates the patterns of coattraction of items that appear in the two VP positions (the VP in the matrix clause, and the VP in the infinitive subordinate clause) in the English accusative-with-bare-infinitive constru......Drawing on usage-based cognitively oriented construction grammar, this paper investigates the patterns of coattraction of items that appear in the two VP positions (the VP in the matrix clause, and the VP in the infinitive subordinate clause) in the English accusative...... relations of English accusatives-with-bare-infinitives through the relations of semantic coherence between the two VPs....

Mesoscopic Fluctuations for the Thinned Circular Unitary Ensemble

Science.gov (United States)

Berggren, Tomas; Duits, Maurice

2017-09-01

In this paper we study the asymptotic behavior of mesoscopic fluctuations for the thinned Circular Unitary Ensemble. The effect of thinning is that the eigenvalues start to decorrelate. The decorrelation is stronger on the larger scales than on the smaller scales. We investigate this behavior by studying mesoscopic linear statistics. There are two regimes depending on the scale parameter and the thinning parameter. In one regime we obtain a CLT of a classical type and in the other regime we retrieve the CLT for CUE. The two regimes are separated by a critical line. On the critical line the limiting fluctuations are no longer Gaussian, but described by infinitely divisible laws. We argue that this transition phenomenon is universal by showing that the same transition and their laws appear for fluctuations of the thinned sine process in a growing box. The proofs are based on a Riemann-Hilbert problem for integrable operators.

Orthogonality preserving infinite dimensional quadratic stochastic operators

International Nuclear Information System (INIS)

Akın, Hasan; Mukhamedov, Farrukh

2015-01-01

In the present paper, we consider a notion of orthogonal preserving nonlinear operators. We introduce π-Volterra quadratic operators finite and infinite dimensional settings. It is proved that any orthogonal preserving quadratic operator on finite dimensional simplex is π-Volterra quadratic operator. In infinite dimensional setting, we describe all π-Volterra operators in terms orthogonal preserving operators

Nearest Neighbor Estimates of Entropy for Multivariate Circular Distributions

Directory of Open Access Journals (Sweden)

Neeraj Misra

2010-05-01

Full Text Available In molecular sciences, the estimation of entropies of molecules is important for the understanding of many chemical and biological processes. Motivated by these applications, we consider the problem of estimating the entropies of circular random vectors and introduce non-parametric estimators based on circular distances between n sample points and their k th nearest neighbors (NN, where k (≤ n – 1 is a fixed positive integer. The proposed NN estimators are based on two different circular distances, and are proven to be asymptotically unbiased and consistent. The performance of one of the circular-distance estimators is investigated and compared with that of the already established Euclidean-distance NN estimator using Monte Carlo samples from an analytic distribution of six circular variables of an exactly known entropy and a large sample of seven internal-rotation angles in the molecule of tartaric acid, obtained by a realistic molecular-dynamics simulation.

Seismic distortions of a deep circular tunnel in elastic slightly anisotropic ground

Directory of Open Access Journals (Sweden)

Antonio Bobet

2017-06-01

Full Text Available Tunnels must withstand not only the demands stemming from normal working conditions but also from extreme events such as earthquakes. Indeed, there is consistent evidence in the technical literature that indicates that tunnels are vulnerable to damage and must be designed to adequately support the demand imposed by the earthquake. Such demand should be estimated using dynamic numerical methods that include soil-structure interaction and incorporate realistic models for the support and surrounding ground. For preliminary analysis, however, or when the seismic demand is insufficient to take the ground beyond its elastic regime, analytical solutions may provide a reasonable estimate of the tunnel behavior, especially if the tunnel is sufficiently far from the seismic source such that a pseudo-static analysis is acceptable. Most analytical solutions are based on the assumption that the ground is isotropic, which may not be realistic, as e.g. depositional processes may result in engineering properties that depend on the direction of deposition. The work presented in the paper builds on the results by Bobet (2011, 2016 who provided closed-form solutions for deep tunnels in elastic transversely anisotropic ground; however, the paper provides much simpler solutions for those cases where the ground is slightly anisotropic. A comparison between the approximate and the exact solutions shows that the errors are negligible when the ground anisotropy is small and grow, albeit slowly, as the ground anisotropy increases. The conclusion applies to different loading conditions, drained and undrained, and to different ground-support interfaces, tied or frictionless.

Progress in the analysis of non-axisymmetric wave propagation in a homogeneous solid circular cylinder of a piezoelectric transversely isotropic material

CSIR Research Space (South Africa)

Every, AG

2010-01-01

Full Text Available Non-axisymmetric waves in a free homogeneous piezoelectric cylinder of transversely isotropic material with axial polarization are investigated on the basis of the linear theory of elasticity and linear electromechanical coupling. The solution...

Finiteness properties of congruence classes of infinite matrices

NARCIS (Netherlands)

Eggermont, R.H.

2014-01-01

We look at spaces of infinite-by-infinite matrices, and consider closed subsets that are stable under simultaneous row and column operations. We prove that up to symmetry, any of these closed subsets is defined by finitely many equations.

Ergodicity and Parameter Estimates for Infinite-Dimensional Fractional Ornstein-Uhlenbeck Process

International Nuclear Information System (INIS)

Maslowski, Bohdan; Pospisil, Jan

2008-01-01

Existence and ergodicity of a strictly stationary solution for linear stochastic evolution equations driven by cylindrical fractional Brownian motion are proved. Ergodic behavior of non-stationary infinite-dimensional fractional Ornstein-Uhlenbeck processes is also studied. Based on these results, strong consistency of suitably defined families of parameter estimators is shown. The general results are applied to linear parabolic and hyperbolic equations perturbed by a fractional noise

Analytical Solution of Displacements Around Circular Openings in Generalized Hoek-Brown Rocks

Directory of Open Access Journals (Sweden)

Huang Houxu

2017-09-01

Full Text Available The rock in plastic region is divided into numbers of elements by the slip lines, resulted from shear localization. During the deformation process, the elements will slip along the slip lines and the displacement field is discontinuous. Slip lines around circular opening in isotropic rock, subjected to hydrostatic stress are described by the logarithmic spirals. Deformation of the plastic region is mainly attributed to the slippage. Relationship between the shear stresses and slippage on slip lines is presented, based on the study of Revuzhenko and Shemyakin. Relations between slippage and rock failure are described, based on the elastic-brittle-plastic model. An analytical solution is presented for the plane strain analysis of displacements around circular openings in the Generalized Hoek-Brown rock. With properly choosing of slippage parameters, results obtained by using the proposed solution agree well with those presented in published sources.

Numerical solution of the elastic non-axial contact between pellet and cladding of fuel rod in PWR

International Nuclear Information System (INIS)

Zymak, J.

1987-08-01

Elastic non-axial contacts between the pellet and the cladding of a fuel rod in a pressurized water reactor were calculated. The existence and the uniqueness of the solution were proved. The problem was approximated by the finite element method and quadratic programming was used for the solution. The results will be used in the solution of the probabilistic model of a fuel rod with non-axial pellets in a PWR. (author). 10 figs., 4 tabs., 10 refs

Elastic scattering and total cross section at very high energies

International Nuclear Information System (INIS)

Castaldi, R.; Sanguinetti, G.

1985-01-01

The aim of this review is to summarize the recent progress in the field of elastic scattering and total cross section in this new energy domain. In Section 2 a survey of the experimental situation is outlined. The most significant data are presented, with emphasis on the interpretation, not the specific details or technicalities. This section is therefore intended to give a self-contained look at the field, especially for the nonspecialist. In Section 3, hadron scattering at high energy is described in an impact parameter picture, which provides a model-independent intuitive geometrical representation. The diffractive character of elastic scattering, seen as the shadow of inelastic absorption, is presented as a consequence of unitarity in the s-channel. Spins are neglected throughout this review, inasmuch as the asymptotic behavior in the very high-energy limit is the main concern here. In Section 4 some relevant theorems are recalled on the limiting behavior of hadron-scattering amplitudes at infinite energy. There is also a brief discussion on how asymptotically rising total cross sections imply scaling properties in the elastic differential cross sections. A quick survey of eikonal models is presented and their predictions are compared with ISR and SPS Collider data

Operational Circulars

CERN Multimedia

2003-01-01

Operational Circular N° 4 - April 2003 Conditions for use by members of the CERN personnel of vehicles belonging to or rented by CERN - This circular has been drawn up. Operational Circular N° 5 - October 2000 Use of CERN computing facilities - Further details on the personal use of CERN computing facilities Operational Circular N° 5 and its Subsidiary Rules http://cern.ch/ComputingRules defines the rules for the use of CERN computing facilities. One of the basic principles governing such use is that it must come within the professional duties of the user concerned, as defined by the user's divisional hierarchy. However, personal use of the computing facilities is tolerated or allowed provided : a) It is in compliance with Operational Circular N° 5 and not detrimental to official duties, including those of other users; b) the frequency and duration is limited and there is a negligible use of CERN resources; c) it does not constitute a political, commercial and/or profit-making activity; d) it is not...

Circular economy and waste to energy

Science.gov (United States)

Rada, E. C.; Ragazzi, M.; Torretta, V.; Castagna, G.; Adami, L.; Cioca, L. I.

2018-05-01

Waste management in European Union has long being regulated by the 4Rs principle, i.e. reduction, reuse, recycling, recovery, with landfill disposal as the last option. This vision recently led the European Union (especially since 2015) to the introduction of virtuous goals based on the rejection of linear economy in favour of circular economy strongly founded on materials recovery. In this scenario, landfill disposal option will disappear, while energy recovery may appear controversial when not applied to biogas production from anaerobic digestion. The present work aims to analyse the effects that circular economy principles introduced in the European Union context will have on the thermochemical waste treatment plants design. Results demonstrate that indirect combustion (gasification + combustion) along with integrated vitrification of the non-combustible fraction of treated waste will have a more relevant role in the field of waste treatment than in the past, thanks to the compliance of this option with the principles of circular economy.

New non-linear model of groundwater recharge: Inclusion of memory, heterogeneity and visco-elasticity

Directory of Open Access Journals (Sweden)

Spannenberg Jescica

2017-09-01

Full Text Available Fractional differentiation has adequate use for investigating real world scenarios related to geological formations associated with elasticity, heterogeneity, viscoelasticity, and the memory effect. Since groundwater systems exist in these geological formations, modelling groundwater recharge as a real world scenario is a challenging task to do because existing recharge estimation methods are governed by linear equations which make use of constant field parameters. This is inadequate because in reality these parameters are a function of both space and time. This study therefore concentrates on modifying the recharge equation governing the EARTH model, by application of the Eton approach. Accordingly, this paper presents a modified equation which is non-linear, and accounts for parameters in a way that it is a function of both space and time. To be more specific, herein, recharge and drainage resistance which are parameters within the equation, became a function of both space and time. Additionally, the study entailed solving the non-linear equation using an iterative method as well as numerical solutions by means of the Crank-Nicolson scheme. The numerical solutions were used alongside the Riemann-Liouville, Caputo-Fabrizio, and Atangana-Baleanu derivatives, so that account was taken for elasticity, heterogeneity, viscoelasticity, and the memory effect. In essence, this paper presents a more adequate model for recharge estimation.

Information Circulars

International Nuclear Information System (INIS)

1969-01-01

Information circulars are published from time to time under the symbol INFCIRC/. . . . for the purpose of bringing matters of general interest to the attention of all Members of the Agency. A list of the circulars which were of current interest on 15 January 1969 is given below, followed by an index to their subject matter. Other circulars can be traced by reference to earlier issues of the present document.

Information Circulars

Energy Technology Data Exchange (ETDEWEB)

NONE

1969-01-24

Information circulars are published from time to time under the symbol INFCIRC/. . . . for the purpose of bringing matters of general interest to the attention of all Members of the Agency. A list of the circulars which were of current interest on 15 January 1969 is given below, followed by an index to their subject matter. Other circulars can be traced by reference to earlier issues of the present document.

Entanglement evolution after connecting finite to infinite quantum chains

International Nuclear Information System (INIS)

Eisler, V; Peschel, I; Karevski, D; Platini, T

2008-01-01

We study zero-temperature XX chains and transverse Ising chains and join an initially separate finite piece on one or on both sides to an infinite remainder. In both critical and non-critical systems we find a typical increase of the entanglement entropy after the quench, followed by a slow decay towards the value of the homogeneous chain. In the critical case, the predictions of conformal field theory are verified for the first phase of the evolution, while at late times a step structure can be observed

Transient thermal stresses in composite hollow circular cylinder due to partial heat generation

International Nuclear Information System (INIS)

Goshima, Takahito; Miyao, Kaju

1979-01-01

Clad materials are adopted for the machines and structures used in contact with high temperature, corrosive atmosphere in view of their strength and economy. Large thermal stress sometimes arises in clad cylinders due to uneaven temperature field and the difference in linear thermal expansion. Vessels are often heated uneavenly, and shearing stress occurs, which is not observed in uniform heating. In this study, infinitely long, concentric cylinders of two layers were analyzed, when the internal heat changing in stepped state is generated in cylindrical form. The unsteady thermal stress occurred was determined, using thermo-elastic potential and stress functions, and assuming the thermal properties and elastic modulus of materials as constant regardless of the temperature. Laplace transformation was used, and the basic equations for thermo-elastic displacement were employed as the basis of calculation. The analysis of the temperature distribution and stress is explained. Numerical calculation was carried out on the example of an internal cylinder of SUS 304 stainless steel and an external cylinder of mild steel. The maximum shearing stress occurred in the direction of 40 deg from the heat source, and was affected largely by the position of heat generation. The effect became remarkable as time elapsed. (Kako, I.)

Non-intrusive investigation of flow and heat transfer characteristics of a channel with a built-in circular cylinder

Science.gov (United States)

Vyas, Apoorv; Mishra, Biswajit; Agrawal, Atul; Srivastava, Atul

2018-03-01

Interferometry-based experimental investigation of heat transfer phenomena associated with a channel fitted with a circular cylinder has been reported. Experiments have been performed with water as the working fluid, and the range of Reynolds number considered is 75 ≤ Re ≤ 165. The circular cylinder, placed at the inlet section of the channel, provides a blockage ratio of 0.5. The experimental methodology has been benchmarked against the results of transient numerical simulations. In order to assess the performance of the channel fitted with a circular cylinder for possible heat transfer enhancement from the channel wall(s), experiments have also been performed on a plane channel (without a cylinder). The interferometry-based experiments clearly highlighted the influence of the built-in cylinder in generating the flow instabilities and alterations in the thermal boundary layer profile along the heated wall of the channel. The phenomenon of vortex shedding behind the cylinder was successfully captured. A gradual increase in the vortex shedding frequency was observed with increasing Reynolds number. Quantitative data in the form of two-dimensional temperature distributions revealed an increase in the strength of wall thermal gradients in the wake region of the cylinder due to the periodic shedding of the vortices. In turn, a clear enhancement in the wall heat transfer rates was observed for the case of the channel fitted with a cylinder vis-à-vis the plane channel. To the best of the knowledge of the authors, the work reported is one of the first attempts to provide the planar field experimental data for a channel configuration with a built-in circular cylinder using non-intrusive imaging techniques and has the potential to serve as one of the benchmark studies for validating the existing as well as future numerical studies in the related area.

The Infinite Hotel

Science.gov (United States)

Wanko, Jeffrey J.

2009-01-01

This article provides a historical context for the debate between Georg Cantor and Leopold Kronecker regarding the cardinality of different infinities and incorporates the short story "Welcome to the Hotel Infinity," which uses the analogy of a hotel with an infinite number of rooms to help explain this concept. Wanko makes use of this history and…

Anisotropy function for proton-proton elastic scattering

International Nuclear Information System (INIS)

Saleem, Mohammad; Fazal-e-Aleem; Azhar, I.A.

1990-01-01

By using the generalized Chou-Yang model and the experimental data on pp elastic scattering at 53 GeV, the anisotropy function which reflects the non-isotropic nature of elastic scattering is computed for the reaction pp→pp. (author)

An Accurate Study on Capacitive Microphone with Circular Diaphragm Using a Higher Order Elasticity Theory

Directory of Open Access Journals (Sweden)

Shakiba Dowlati

Full Text Available Abstract This study has been undertaken to investigate the mechanical behavior of the capacitive microphone with clamped circular diaphragm using modified couple stress theory in comparison to the classical one. Presence of the length scale parameter in modified couple stress theory provides the means to evaluate the size effect on the microphone mechanical behavior. Investigating Pull-in phenomenon and dynamic behavior of the microphone are the matters provided due to the application of a step DC voltage. Also the effects of different air damping coefficients on dynamic pull-in voltage and pull-in time have been studied. The output level or sensitivity of the microphone has been studied by investigating the frequency response in term of magnitude for different length scale parameters to figure out how the length scale parameter affects on the sensitivity of the capacitive microphone. To achieve these ends, the nonlinear differential equation of the circular diaphragm has been extracted using Kirchhoff thin plate theory. Then, a Step-by-Step Linearization Method (SSLM has been used to escape from the nonlinearity of the differential equation. Afterwards, Galerkin-based reduced-order model has been applied to solve the obtained equation.

(Ooraftelbaarheid

Directory of Open Access Journals (Sweden)

D.F.M. Strauss

2011-09-01

Full Text Available (Nondenumerability The focus of this article is the rise of modern set theory which, according to Meschkowski, coincides with the first proof given in 1874 by Cantor of the non-denumerability of the real numbers. Later on he developed his well-known diagonal proof, which occupies a central position in this article. The argument of this article is directed towards the implicit supposition of the diagonal proof, to wit the acceptance of the actual infinite (preferably designated as the at once infinite. Without this assumption no conclusion to non-denumerability is possible. Various mathematicians and mathematical traditions of the twentieth century questioned the use of the actual infinite. A closer investigation is conducted in respect of two opponents of the actual infinite, namely Kaufmann and Wolff. The circular reasoning contained in their approach is highlighted and as alternative a non-circular understanding of the at once infinite is explained. At the same time the assumed exact nature (and neutrality of mathematics is questioned (in the spirit of „Koers‟ as a Christian academic journal. This contemplation disregards the question of what mathematics is (for example by including topology, category theory and topos theory, which would have diverted our attention to contemporary views of figures such as Tait, Penelope and Shapiro who, among others, acts as the editors of and contributors to the encompassing work „Handbook of Philosophy of Mathematics and Logic‟ (2005.

Infinite dimensional groups and algebras in quantum physics

International Nuclear Information System (INIS)

Ottesen, J.T.

1995-01-01

This book is an introduction to the application of infite-dimensional groups and algebras in quantum physics. Especially considered are the spin representation of the infinite-dimensional orthogonal group, the metaplectic representation of the infinite-dimensional symplectic groups, and Loop and Virasoro algebras. (HSI)

Anisotropy function for proton-proton elastic scattering

Energy Technology Data Exchange (ETDEWEB)

Saleem, Mohammad; Fazal-e-Aleem; Azhar, I.A. (Punjab Univ., Lahore (Pakistan). Centre for High Energy Physics)

1990-07-01

By using the generalized Chou-Yang model and the experimental data on pp elastic scattering at 53 GeV, the anisotropy function which reflects the non-isotropic nature of elastic scattering is computed for the reaction pp{yields}pp. (author).

About the Infinite Repetition of Histories in Space

Directory of Open Access Journals (Sweden)

Manuel Alfonseca

2014-08-01

Full Text Available This paper analyzes two different proposals, one by Ellis and Brundrit, based on classical relativistic cosmology, the other by Garriga and Vilenkin, based on the DH interpretation of quantum mechanics, both concluding that, in an infinite universe, planets and beings must be repeated an infinite number of times. We point to possible shortcomings in these arguments. We conclude that the idea of an infinite repetition of histories in space cannot be considered strictly speaking a consequence of current physics and cosmology. Such ideas should be seen rather as examples of «ironic science» in the terminology of John Horgan.

Dynamics with infinitely many derivatives: variable coefficient equations

International Nuclear Information System (INIS)

Barnaby, Neil; Kamran, Niky

2008-01-01

Infinite order differential equations have come to play an increasingly significant role in theoretical physics. Field theories with infinitely many derivatives are ubiquitous in string field theory and have attracted interest recently also from cosmologists. Crucial to any application is a firm understanding of the mathematical structure of infinite order partial differential equations. In our previous work we developed a formalism to study the initial value problem for linear infinite order equations with constant coefficients. Our approach relied on the use of a contour integral representation for the functions under consideration. In many applications, including the study of cosmological perturbations in nonlocal inflation, one must solve linearized partial differential equations about some time-dependent background. This typically leads to variable coefficient equations, in which case the contour integral methods employed previously become inappropriate. In this paper we develop the theory of a particular class of linear infinite order partial differential equations with variable coefficients. Our formalism is particularly well suited to the types of equations that arise in nonlocal cosmological perturbation theory. As an example to illustrate our formalism we compute the leading corrections to the scalar field perturbations in p-adic inflation and show explicitly that these are small on large scales.

Marangoni elasticity of flowing soap films

OpenAIRE

Kim, Ildoo; Mandre, Shreyas

2016-01-01

We measure the Marangoni elasticity of a flowing soap film to be 22 dyne/cm irrespective of its width, thickness, flow speed, or the bulk soap concentration. We perform this measurement by generating an oblique shock in the soap film and measuring the shock angle, flow speed and thickness. We postulate that the elasticity is constant because the film surface is crowded with soap molecules. Our method allows non-destructive measurement of flowing soap film elasticity, and the value 22 dyne/cm ...

Split-Ring Springback Simulations with the Non-associated Flow Rule and Evolutionary Elastic-Plasticity Models

Science.gov (United States)

Lee, K. J.; Choi, Y.; Choi, H. J.; Lee, J. Y.; Lee, M. G.

2018-06-01

Finite element simulations and experiments for the split-ring test were conducted to investigate the effect of anisotropic constitutive models on the predictive capability of sheet springback. As an alternative to the commonly employed associated flow rule, a non-associated flow rule for Hill1948 yield function was implemented in the simulations. Moreover, the evolution of anisotropy with plastic deformation was efficiently modeled by identifying equivalent plastic strain-dependent anisotropic coefficients. Comparative study with different yield surfaces and elasticity models showed that the split-ring springback could be best predicted when the anisotropy in both the R value and yield stress, their evolution and variable apparent elastic modulus were taken into account in the simulations. Detailed analyses based on deformation paths superimposed on the anisotropic yield functions predicted by different constitutive models were provided to understand the complex springback response in the split-ring test.

Design for Circular Behaviour: Considering Users in a Circular Economy

Directory of Open Access Journals (Sweden)

Thomas Wastling

2018-05-01

Full Text Available In a linear economy, a product is manufactured and sold to a customer. Then, little concern is given to what the user actually does with it when they have it. However, in a circular economy where the aim is to circulate products at their highest level of value, the customer’s behaviour can become an important part of the system. Circular design strategies have tended to focus on the physical aspects of a product (e.g., disassembly, material selection, but the design of products and services can also have an influence on user behaviour and, to date, this aspect of circular design has not been fully explored. This project aims to define what key user behaviours are required for circular business models to work and to outline how design can enable these ‘circular behaviours’. This research project consists of a literature review, case study analysis and expert interviews with practitioners. A theoretical framework for designing products and services to encourage circular behaviour is developed. This work provides an initial step towards a better understanding of the user’s role in the transition to a circular economy as well as a preliminary model for how design for behaviour change strategies could be implemented in this context.

Fractional supersymmetry and infinite dimensional lie algebras

International Nuclear Information System (INIS)

Rausch de Traubenberg, M.

2001-01-01

In an earlier work extensions of supersymmetry and super Lie algebras were constructed consistently starting from any representation D of any Lie algebra g. Here it is shown how infinite dimensional Lie algebras appear naturally within the framework of fractional supersymmetry. Using a differential realization of g this infinite dimensional Lie algebra, containing the Lie algebra g as a sub-algebra, is explicitly constructed

Elastic properties of ultrathin diamond/AlN membranes

International Nuclear Information System (INIS)

Zuerbig, V.; Hees, J.; Pletschen, W.; Sah, R.E.; Wolfer, M.; Kirste, L.; Heidrich, N.; Nebel, C.E.; Ambacher, O.; Lebedev, V.

2014-01-01

Nanocrystalline diamond- (NCD) and AlN-based ultrathin single layer and bilayer membranes are investigated towards their mechanical properties. It is shown that chemo-mechanical polishing and heavy boron doping of NCD thin films do not impact the elastic properties of NCD layers as revealed by negligible variations of the NCD Young's modulus (E). In addition, it is demonstrated that the combination of NCD elastic layer and AlN piezo-actuator is highly suitable for the fabrication of mechanically stable ultrathin membranes in comparison to AlN single layer membranes. The elastic parameters of NCD/AlN heterostructures are mainly determined by the outstanding high Young's modulus of NCD (E = 1019 ± 19 GPa). Such ultrathin unimorph membranes allow for fabrication of piezo-actuated AlN/NCD microlenses with tunable focus length. - Highlights: • Mechanical properties of nanocrystalline diamond (NCD) and AlN circular membranes • No influence of polishing of NCD thin films on the mechanical properties of NCD • No influence of heavy boron-doping on the mechanical properties of NCD • Demonstration of mechanically stable piezo-actuated NCD/AlN membranes • Reported performance of AlN/NCD microlenses with adjustable focus length

Optimization and control of plasma shape and current profile in non-circular cross-section tokamaks

International Nuclear Information System (INIS)

Moore, R.W.; Bernard, L.C.; Chan, V.S.

1981-01-01

Tokamaks with elongated, non-circular cross-sections are under consideration as fusion reactors because they have the potential for stable operation at high β. Ideal MHD theory, however, predicts that careful current profile control will be required to achieve the potential high-β advantages of non-circular cross-sections. In this paper, high-β equilibria which are stable to all ideal MHD modes are found by optimizing the plasma shape and current profile for doublets, up-down asymmetric dees, and symmetric dees. The ideal MHD stability of these equilibria for low toroidal mode number n is analysed with a global MHD stability code, GATO. The stability to high-n modes is analysed with a localized ballooning code, BLOON. The attainment of high β is facilitated by an automated optimization search on shape and current parameters. The equilibria are calculated with a free-boundary equilibrium code using coils appropriate for the Doublet III experimental device. The optimal equilibria are characterized by broad current profiles with values of βsub(poloidal) approximately equal to 1. Experimental realization of the shapes and current profiles giving the highest β limits is explored with a 1 1/2-D transport code, which simulates the time evolution of the 2-D MHD equilibrium while calculating consistent current profiles from a 1-D transport model. Transport simulations indicate that nearly optimal shapes may be obtained provided that the currents in the field-shaping coils are appropriately programmed and the plasma current profile is sufficiently broad. Obtaining broad current profiles is possible by current ramping, neutral-beam heating, and electron-cyclotron heating. With combinations of these techniques it is possible to approach the optimum β predicted by the MHD theory. (author)

Large non-circular RFP experiments at Wisconsin

International Nuclear Information System (INIS)

Sprott, J.C.; Dexter, R.N.; Prager, S.C.; Almagri, A.F.; Assadi, S.; Sarff, J.S.

1986-01-01

By removing the internal rings from the Levitated Octupole vacuum vessel, a large, non-circular RFP was produced. The major radius is 1.39 m, and the cross section is about 1 m/sup 2/. The device is unconventional in that the vacuum vessel, which consists of 5-cm thick aluminum with a single poloidal and toroidal gap, serves as the vacuum liner, conducting shell, and poloidal and toroidal field coils. A toroidal field of up to about 1 kG can be produced, and the poloidal field is driven by a 600 kJ capacitor bank through a 2-volt-second iron core. Discharges are initiated with 4200 volts per turn using self-reversal of the toroidal field in order to prevent arcing of the poloidal gap which is exposed to the plasma. The gap is protected with a 20-cm wide strip of ceramic. The best RFP discharges have a peak current of ≅200 kA and a duration of ≅ 10 msec. The toroidal field reverses when the current reaches ≅100 kA, making this one of the lowest current density RFP's in existence. The current ramps up to the final value over ≅10 resistive diffusion times and terminates only because the volt-second limit of the iron core is reached. The F-θ trajectory lies slightly to the right of the λ=constant theory as do all other RFP devices. Discharges have been produced with θ up to 2.5 and F as low as -0.8. A feature of the device is that it is capable of producing discharges with plasma current of ≅100 kA and ≅10 msec duration over a wide range of safety factor from the q>1 tokamak limit to the deeply-reversed, RFP limit. The highest current discharges (≅300 kA) are obtained at q≅0.5

Ionization, photoelectron dynamics and elastic scattering in relativistic, ultra-strong field

Science.gov (United States)

Luo, Sui

Ultrastrong laser-matter interaction has direct bearing to next generation technologies including plasma acceleration, laser fusion and attosecond X-ray generation. The commonly known physics in strong field becomes different as one progress to ultrastrong field. The works presented in this dissertation theoretically study the influence of relativistic effect and magnetic component of the laser field on the ionization, photoelectron dynamics and elastic scattering processes. The influence of magnetic component (B laser) of circularly polarized (CP) ultrastrong fields (up to3 x 1022 W/cm2) on atomic bound state dynamics is investigated. The Poincare plots are used to find the changes in trajectory energies are on the order of a few percent for intensities up to1 x 1022 W/cm2. It is found that at intensities where ionization approaches 50% for the bound state, the small changes from Blaser of the circular polarized light can actually result in a several-fold decrease in ionization probability. The force on the bound electron exerted by the Lorentz force from B laser is perpendicular to the rotating plane of the circular polarized light, and this nature makes those trajectories which are aligned away from the minimum in the potential barrier stabilized against tunneling ionization. Our results provide a classical understanding for ionization in ultrastrong fields and indicate that relativistic effects in ultrastrong field ionization may most easily be seen with CP fields. The photoelectron energy spectra from elastic rescattering in ultrastrong laser fields (up to 2x1019 W/cm2) is studied by using a relativistic adaption of a semi-classical three-step recollision model. The Hartree-Fock scattering potentials are used in calculating the elastic rescattering for both hydrogenlike and noble gas species. It is found that there is a reduction in elastic rescattering for intensities beyond 6 x 1016 W/cm2 when the laser Lorentz deflection of the photoelectron exceeds its

Circular dichroism measurements at an x-ray free-electron laser with polarization control

Energy Technology Data Exchange (ETDEWEB)

Hartmann, G.; Shevchuk, I.; Walter, P.; Viefhaus, J. [Deutsches Elektronen-Synchrotron, Notkestraße 85, 22607 Hamburg (Germany); Lindahl, A. O. [PULSE at Stanford, 2575 Sand Hill Road, Menlo Park, California 94025 (United States); Knie, A. [Institut für Physik, University of Kassel, Heinrich-Plett-Str. 40, 34132 Kassel (Germany); Hartmann, N.; Lutman, A. A.; MacArthur, J. P.; Glownia, J. M.; Helml, W.; Huang, Z.; Marinelli, A.; Nuhn, H.-D.; Moeller, S.; Coffee, R. N.; Ilchen, M., E-mail: markus.ilchen@xfel.eu [SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, California 94025 (United States); Buck, J.; Galler, A.; Liu, J. [European XFEL GmbH, Albert-Einstein-Ring 19, 22761 Hamburg (Germany); and others

2016-08-15

A non-destructive diagnostic method for the characterization of circularly polarized, ultraintense, short wavelength free-electron laser (FEL) light is presented. The recently installed Delta undulator at the LCLS (Linac Coherent Light Source) at SLAC National Accelerator Laboratory (USA) was used as showcase for this diagnostic scheme. By applying a combined two-color, multi-photon experiment with polarization control, the degree of circular polarization of the Delta undulator has been determined. Towards this goal, an oriented electronic state in the continuum was created by non-resonant ionization of the O{sub 2} 1s core shell with circularly polarized FEL pulses at hν ≃ 700 eV. An also circularly polarized, highly intense UV laser pulse with hν ≃ 3.1 eV was temporally and spatially overlapped, causing the photoelectrons to redistribute into so-called sidebands that are energetically separated by the photon energy of the UV laser. By determining the circular dichroism of these redistributed electrons using angle resolving electron spectroscopy and modeling the results with the strong-field approximation, this scheme allows to unambiguously determine the absolute degree of circular polarization of any pulsed, ultraintense XUV or X-ray laser source.

Circular dichroism measurements at an x-ray free-electron laser with polarization control

Science.gov (United States)

Hartmann, G.; Lindahl, A. O.; Knie, A.; Hartmann, N.; Lutman, A. A.; MacArthur, J. P.; Shevchuk, I.; Buck, J.; Galler, A.; Glownia, J. M.; Helml, W.; Huang, Z.; Kabachnik, N. M.; Kazansky, A. K.; Liu, J.; Marinelli, A.; Mazza, T.; Nuhn, H.-D.; Walter, P.; Viefhaus, J.; Meyer, M.; Moeller, S.; Coffee, R. N.; Ilchen, M.

2016-08-01

A non-destructive diagnostic method for the characterization of circularly polarized, ultraintense, short wavelength free-electron laser (FEL) light is presented. The recently installed Delta undulator at the LCLS (Linac Coherent Light Source) at SLAC National Accelerator Laboratory (USA) was used as showcase for this diagnostic scheme. By applying a combined two-color, multi-photon experiment with polarization control, the degree of circular polarization of the Delta undulator has been determined. Towards this goal, an oriented electronic state in the continuum was created by non-resonant ionization of the O2 1s core shell with circularly polarized FEL pulses at hν ≃ 700 eV. An also circularly polarized, highly intense UV laser pulse with hν ≃ 3.1 eV was temporally and spatially overlapped, causing the photoelectrons to redistribute into so-called sidebands that are energetically separated by the photon energy of the UV laser. By determining the circular dichroism of these redistributed electrons using angle resolving electron spectroscopy and modeling the results with the strong-field approximation, this scheme allows to unambiguously determine the absolute degree of circular polarization of any pulsed, ultraintense XUV or X-ray laser source.

A numerical study of wave dispersion curves in cylindrical rods with circular cross-section

Directory of Open Access Journals (Sweden)

Valsamos G.

2013-06-01

Full Text Available This work presents a finite element approach for modeling longitudinal wave propagation in thick cylindrical rods with circular cross-section. The formulation is based on simple time domain response of the structure to a properly chosen excitation, and is calculated with an explicit finite element solver. The proposed post-treatment procedure identifies the wavenumber for each mode of wave propagation at the desired frequency. The procedure is implemented and integrated in an efficient way in the explicit finite element code Europlexus. The numerical results are compared to the analytical ones obtained from the solution of the Pochhammer — Chree equation, which provides the dispersion curves for wavetrains in solid cylinders of infinite length.

An elastic, low-background vertical focusing element for a doubly focusing neutron monochromator

International Nuclear Information System (INIS)

Smee, Stephen A.; Brand, Paul C.; Barry, Dwight D.; Broholm, Collin L.; Anand, Dave K.

2001-01-01

A novel, variable radius of curvature, device for the focusing of neutrons is presented. This elastic element consists of a thin variable thickness, constant width, aluminum blade to which diffracting crystals can be attached. When buckled, the blade assumes a circular focal shape, the radius of which is easily controlled by the relative displacement of supporting pivots. Precision electromechanical and optical measurements show that the slope of the buckled blade conforms to a circular arc to within 0.15 degree sign for radii in the range 900 mm< R<10 000 mm. This easily scalable, low mass mechanism is well suited for use in a focusing neutron monochromator, as the parasitic scattering typically associated with traditional lead screw and lever mechanisms is greatly reduced

Infinite series

CERN Document Server

Hirschman, Isidore Isaac

2014-01-01

This text for advanced undergraduate and graduate students presents a rigorous approach that also emphasizes applications. Encompassing more than the usual amount of material on the problems of computation with series, the treatment offers many applications, including those related to the theory of special functions. Numerous problems appear throughout the book.The first chapter introduces the elementary theory of infinite series, followed by a relatively complete exposition of the basic properties of Taylor series and Fourier series. Additional subjects include series of functions and the app

Non-periodic homogenization of 3-D elastic media for the seismic wave equation

Science.gov (United States)

Cupillard, Paul; Capdeville, Yann

2018-05-01

Because seismic waves have a limited frequency spectrum, the velocity structure of the Earth that can be extracted from seismic records has a limited resolution. As a consequence, one obtains smooth images from waveform inversion, although the Earth holds discontinuities and small scales of various natures. Within the last decade, the non-periodic homogenization method shed light on how seismic waves interact with small geological heterogeneities and `see' upscaled properties. This theory enables us to compute long-wave equivalent density and elastic coefficients of any media, with no constraint on the size, the shape and the contrast of the heterogeneities. In particular, the homogenization leads to the apparent, structure-induced anisotropy. In this paper, we implement this method in 3-D and show 3-D tests for the very first time. The non-periodic homogenization relies on an asymptotic expansion of the displacement and the stress involved in the elastic wave equation. Limiting ourselves to the order 0, we show that the practical computation of an upscaled elastic tensor basically requires (i) to solve an elastostatic problem and (ii) to low-pass filter the strain and the stress associated with the obtained solution. The elastostatic problem consists in finding the displacements due to local unit strains acting in all directions within the medium to upscale. This is solved using a parallel, highly optimized finite-element code. As for the filtering, we rely on the finite-element quadrature to perform the convolution in the space domain. We end up with an efficient numerical tool that we apply on various 3-D models to test the accuracy and the benefit of the homogenization. In the case of a finely layered model, our method agrees with results derived from Backus. In a more challenging model composed by a million of small cubes, waveforms computed in the homogenized medium fit reference waveforms very well. Both direct phases and complex diffracted waves are

Controlled elastic postbuckling of bilaterally constrained non-prismatic columns: application to enhanced quasi-static energy harvesters

Science.gov (United States)

Liu, Suihan; Burgueño, Rigoberto

2016-12-01

Axially compressed bilaterally constrained columns, which can attain multiple snap-through buckling events in their elastic postbuckling response, can be used as energy concentrators and mechanical triggers to transform external quasi-static displacement input to local high-rate motions and excite vibration-based piezoelectric transducers for energy harvesting devices. However, the buckling location with highest kinetic energy release along the element, and where piezoelectric oscillators should be optimally placed, cannot be controlled or isolated due to the changing buckling configurations. This paper proposes the concept of stiffness variations along the column to gain control of the buckling location for optimal placement of piezoelectric transducers. Prototyped non-prismatic columns with piece-wise varying thickness were fabricated through 3D printing for experimental characterization and numerical simulations were conducted using the finite element method. A simple theoretical model was also developed based on the stationary potential energy principle for predicting the critical line contact segment that triggers snap-through events and the buckling morphologies as compression proceeds. Results confirm that non-prismatic column designs allow control of the buckling location in the elastic postbuckling regime. Compared to prismatic columns, non-prismatic designs can attain a concentrated kinetic energy release spot and a higher number of snap-buckling mode transitions under the same global strain. The direct relation between the column’s dynamic response and the output voltage from piezoelectric oscillator transducers allows the tailorable postbuckling response of non-prismatic columns to be used as multi-stable energy concentrators with enhanced performance in micro-energy harvesters.

First general solutions for unidirectional motions of rate type fluids over an infinite plate

Directory of Open Access Journals (Sweden)

Constantin Fetecau

2015-09-01

Full Text Available Based on a simple but important remark regarding the governing equation for the non-trivial shear stress corresponding to the motion of a fluid over an infinite plate, exact solutions are established for the motion of Oldroyd-B fluids due to the plate that applies an arbitrary time-dependent shear stress to the fluid. These solutions, that allow us to provide the first exact solutions for motions of rate type fluids produced by an infinite plate that applies constant, constantly accelerating or oscillating shears stresses to the fluid, can easily be reduced to the similar solutions for Maxwell, second grade or Newtonian fluids performing the same motion. Furthermore, the obtained solutions are used to develop general solutions for the motion induced by a moving plate and to correct or recover as special cases different known results from the existing literature. Consequently, the motion problem of such fluids over an infinite plate that is moving in its plane or applies a shear stress to the fluid is completely solved.

Anisotropy function for pion-proton elastic scattering

Energy Technology Data Exchange (ETDEWEB)

Saleem, Mohammad; Fazal-e-Aleem; Rashid, Haris

1988-09-01

By using the generalised Chou-Yang model and the experimental data on ..pi../sup -/p elastic scattering at 200 GeV/c, the anisotropy function which reflects the non-isotropic nature of elastic scattering is computed for the reaction ..pi../sup -/p -> ..pi../sup -/p.

Anisotropy function for pion-proton elastic scattering

International Nuclear Information System (INIS)

Saleem, Mohammad; Fazal-e-Aleem; Rashid, Haris

1988-01-01

By using the generalised Chou-Yang model and the experimental data on π - p elastic scattering at 200 GeV/c, the anisotropy function which reflects the non-isotropic nature of elastic scattering is computed for the reaction π - p → π - p. (author)

Inequality for the infinite-cluster density in Bernoulli percolation

International Nuclear Information System (INIS)

Chayes, J.T.; Chayes, L.

1986-01-01

Under a certain assumption (which is satisfied whenever there is a dense infinite cluster in the half-space), we prove a differential inequality for the infinite-cluster density, P/sub infinity/(p), in Bernoulli percolation. The principal implication of this result is that if P/sub infinity/(p) vanishes with critical exponent β, then β obeys the mean-field bound β< or =1. As a corollary, we also derive an inequality relating the backbone density, the truncated susceptibility, and the infinite-cluster density

Acoustic loading effects on oscillating rod bundles

International Nuclear Information System (INIS)

Lin, W.H.

1980-01-01

An analytical study of the interaction between an infinite acoustic medium and a cluster of circular rods is described. The acoustic field due to oscillating rods and the acoustic loading on the rods are first solved in a closed form. The acoustic loading is then used as a forcing function for rod responses, and the acousto-elastic couplings are solved simultaneously. Numerical examples are presented for several cases to illustrate the effects of various system parameters on the acoustic reaction force coefficients. The effect of the acoustic loading on the coupled eigenfrequencies are discussed

Wigner's infinite spin representations and inert matter

Energy Technology Data Exchange (ETDEWEB)

Schroer, Bert [CBPF, Rio de Janeiro (Brazil); Institut fuer Theoretische Physik FU-Berlin, Berlin (Germany)

2017-06-15

Positive energy ray representations of the Poincare group are naturally subdivided into three classes according to their mass and spin content: m > 0, m = 0 finite helicity and m = 0 infinite spin. For a long time the localization properties of the massless infinite spin class remained unknown, until it became clear that such matter does not permit compact spacetime localization and its generating covariant fields are localized on semi-infinite space-like strings. Using a new perturbation theory for higher spin fields we present arguments which support the idea that infinite spin matter cannot interact with normal matter and we formulate conditions under which this also could happen for finite spin s > 1 fields. This raises the question of a possible connection between inert matter and dark matter. (orig.)

Numerical Predictions of Mode Reflections in an Open Circular Duct: Comparison with Theory

Science.gov (United States)

Dahl, Milo D.; Hixon, Ray

2015-01-01

The NASA Broadband Aeroacoustic Stator Simulation code was used to compute the acoustic field for higher-order modes in a circular duct geometry. To test the accuracy of the results computed by the code, the duct was terminated by an open end with an infinite flange or no flange. Both open end conditions have a theoretical solution that was used to compare with the computed results. Excellent comparison for reflection matrix values was achieved after suitable refinement of the grid at the open end. The study also revealed issues with the level of the mode amplitude introduced into the acoustic held from the source boundary and the amount of reflection that occurred at the source boundary when a general nonreflecting boundary condition was applied.

Review of the theory of infinite nuclear matter

International Nuclear Information System (INIS)

Llano, M. de; Tolmachev, V.V.

1975-01-01

Given a two-body force, there seems to be two distinct starting points in the many-body perturbation-theoretic problem of computing the energy per nucleon of infinite (as well as finite) nuclear matter: ordinary Hartree-Fock theory and the Brueckner theory. The former theory, treated almost exclusively with plane-wave solutions, has long-ago fallen into disuse, to yield to the latter, apparently more sophisticated, theory. After a brief outline of many-fermion diagramatic techniques, the Brueckner-Bethe-Goldstone series expansion in terms of the density is discussed as a low density, non-ideal Fermi gas theory, whose convergence is analyzed. A calculation based on particle-hole Green's function techniques shows that a nucleon gas condenses to the liquid phase at about 3% of the empirical nuclear matter saturation density. The analogy between the BBG expansion and the virial expansion for a classical or quantum gas is studied with special emphasis on the apparent impossibility of analytical-continuing the latter gas theory to densities in the liquid regime, as first elucidated by Lee and Yang. It is finally argued that ordinary HF theory may provide a good starting point for the eventual understanding of nuclear matter as it gives (in the finite nuclear problem, at any rate) not only the basic liquid properties of a definite density and a surface but also provides independent-particle aspects, avoiding at the same time the idea of n-body clusters appropriate only for dilute gases. This program has to date not been carried out for infinite nuclear matter, mainly because of insufficient knowledge regarding low-energy, non-plane-wave solutions of the HF equations, in the thermodynamic limit [pt

Exact thermal representation of multilayer rectangular structures by infinite plate structures using the method of images

Science.gov (United States)

Palisoc, Arthur L.; Lee, Chin C.

1988-12-01

Using the method of images and the analytical temperature solution to the multilayer infinite plate structure, the thermal profile over finite rectangular multilayer integrated circuit devices can be calculated exactly. The advantage of using the image method lies in the enhanced capability of arriving at an analytical solution for structures where analytical solutions do not apparently exist, e.g., circular or arbitrarily oriented rectangular sources over multilayered rectangular structures. The new approach results in large savings in computer CPU time especially for small sources over large substrates. The method also finds very important applications to integrated circuit devices with heat dissipating elements close to the edge boundaries. Results from two examples indicate that the edge boundaries of a device may also be utilized to remove heat from it. This additional heat removing capability should have important applications in high power devices.

Příklonky a vazaly infinitivu : Clitics and Infinitive Vassals

Directory of Open Access Journals (Sweden)

Ilona Starý Kořánová

2017-12-01

Full Text Available Word order of Czech enclitics is quite difficult to acquire for students of Czech as foreign language. While native speakers can “hear” the correct word order, the foreigner needs a set of rules to guide him. The usual rule for the word order of fixed enclitics seems to be breached quite often. The article focuses on one type of sentences in which the rule for the word order of fixed enclitics is violated, namely in sentences which except for a finite verb include an infinitive and consequently two series of enclitics. The finite verb and the infinitive each syntactically govern (are governor to their respective enclitics which in turn are their subjects (recta. If the infinitive is part of the sentence predicate, the enclitics follow the usual rule of word order unless the infinitive becomes part of the sentence rhema (comments. In that case its subjects precede it. If the infinitive is not part of the sentence predicate (in other words it is subject, object or complement, precedes it then the infinitive subjects follow it. However, if the infinitive is not part of the sentence predicate, and is placed at the sentence end, then its subjects precede it. If the infinitive functions as an attribute to a noun, it follows the noun. If the nominal phrase N + infinitive starts a sentence then the reflexive particle se/si follows the infinitive in 98% of cases. If the enclitic personal pronouns occur in the reversed order, i.e. Acc.–Dat. order, or two dative enclitics follow one immediately after another then the enclitics subjects are as close as possible to their regens/ governor. The so-called contact dative, which does not have a governor, is not bound in this way

On the method of orthogonal projections in the theory of elasticity

Directory of Open Access Journals (Sweden)

Valerii V. Struzhanov

2017-07-01

Full Text Available The method of orthogonal projections applied to the task of determining the stresses in the elastic deformable bodies, which allowed us to relax the requirements to the smoothness of the functions defining external forces and to the components of the tensor of the initial strains, which cause the appearance of balanced self-stresses. Examples of the calculation of quench stresses in a circular cylinder and residual stresses after shrinkage of the binder in composite cylinders made by winding are given.

Bifurcating fronts for the Taylor-Couette problem in infinite cylinders

Science.gov (United States)

Hărăguş-Courcelle, M.; Schneider, G.

We show the existence of bifurcating fronts for the weakly unstable Taylor-Couette problem in an infinite cylinder. These fronts connect a stationary bifurcating pattern, here the Taylor vortices, with the trivial ground state, here the Couette flow. In order to show the existence result we improve a method which was already used in establishing the existence of bifurcating fronts for the Swift-Hohenberg equation by Collet and Eckmann, 1986, and by Eckmann and Wayne, 1991. The existence proof is based on spatial dynamics and center manifold theory. One of the difficulties in applying center manifold theory comes from an infinite number of eigenvalues on the imaginary axis for vanishing bifurcation parameter. But nevertheless, a finite dimensional reduction is possible, since the eigenvalues leave the imaginary axis with different velocities, if the bifurcation parameter is increased. In contrast to previous work we have to use normalform methods and a non-standard cut-off function to obtain a center manifold which is large enough to contain the bifurcating fronts.

Validation of an elastic registration technique to estimate anatomical lung modification in Non-Small-Cell Lung Cancer Tomotherapy

International Nuclear Information System (INIS)

Faggiano, Elena; Cattaneo, Giovanni M; Ciavarro, Cristina; Dell'Oca, Italo; Persano, Diego; Calandrino, Riccardo; Rizzo, Giovanna

2011-01-01

The study of lung parenchyma anatomical modification is useful to estimate dose discrepancies during the radiation treatment of Non-Small-Cell Lung Cancer (NSCLC) patients. We propose and validate a method, based on free-form deformation and mutual information, to elastically register planning kVCT with daily MVCT images, to estimate lung parenchyma modification during Tomotherapy. We analyzed 15 registrations between the planning kVCT and 3 MVCT images for each of the 5 NSCLC patients. Image registration accuracy was evaluated by visual inspection and, quantitatively, by Correlation Coefficients (CC) and Target Registration Errors (TRE). Finally, a lung volume correspondence analysis was performed to specifically evaluate registration accuracy in lungs. Results showed that elastic registration was always satisfactory, both qualitatively and quantitatively: TRE after elastic registration (average value of 3.6 mm) remained comparable and often smaller than voxel resolution. Lung volume variations were well estimated by elastic registration (average volume and centroid errors of 1.78% and 0.87 mm, respectively). Our results demonstrate that this method is able to estimate lung deformations in thorax MVCT, with an accuracy within 3.6 mm comparable or smaller than the voxel dimension of the kVCT and MVCT images. It could be used to estimate lung parenchyma dose variations in thoracic Tomotherapy

Interface effects on elastic behavior of a screw dislocation around double nanowires

International Nuclear Information System (INIS)

Li, Jia; Fang, Qihong; Liu, Youwen

2014-01-01

The elastic behavior of a screw dislocation around double nanowires (NWs) is addressed with taking into account the interface stress effect in controlling mechanical response of nanoscale structures. The stress boundary conditions at the interface of the NWs are modified by incorporating surface/interface stress. The analytic solution of complex functions of the right NW, the infinite matrix and the left NW are obtained by applying the complex variable method. The equilibrium positions and the image force acting on the dislocation of a screw dislocation near one of the NWs are discussed in detail and compared with those obtained within the classical theory of elasticity. It is shown that the NWs possess a significant local softening or hardening at the interface, which can change the nature of the equilibrium positions for the dislocation. The radius ratio between NWs has profound effects on the equilibrium position. Additionally, the soft NW with the positive interface stress inhibits the dislocation motion to enhance its own structural stability.

The infinite limit as an eliminable approximation for phase transitions

Science.gov (United States)

Ardourel, Vincent

2018-05-01

It is generally claimed that infinite idealizations are required for explaining phase transitions within statistical mechanics (e.g. Batterman 2011). Nevertheless, Menon and Callender (2013) have outlined theoretical approaches that describe phase transitions without using the infinite limit. This paper closely investigates one of these approaches, which consists of studying the complex zeros of the partition function (Borrmann et al., 2000). Based on this theory, I argue for the plausibility for eliminating the infinite limit for studying phase transitions. I offer a new account for phase transitions in finite systems, and I argue for the use of the infinite limit as an approximation for studying phase transitions in large systems.

Superconducting spin-triplet-MRAM with infinite magnetoresistance ratio

Energy Technology Data Exchange (ETDEWEB)

Lenk, Daniel; Ullrich, Aladin; Obermeier, Guenter; Mueller, Claus; Krug von Nidda, Hans-Albrecht; Horn, Siegfried; Tidecks, Reinhard [Institut fuer Physik, Universitaet Augsburg, D-86159 Augsburg (Germany); Morari, Roman [Institut fuer Physik, Universitaet Augsburg, D-86159 Augsburg (Germany); D. Ghitsu Institute of Electronic Engineering and Nanotechnologies ASM, Academiei Str. 3/3, MD2028 Kishinev (Moldova, Republic of); Solid State Physics Department, Kazan Federal University, 420008 Kazan (Russian Federation); Zdravkov, Vladimir I. [Institut fuer Physik, Universitaet Augsburg, D-86159 Augsburg (Germany); D. Ghitsu Institute of Electronic Engineering and Nanotechnologies ASM, Academiei Str. 3/3, MD2028 Kishinev (Moldova, Republic of); Institute of Applied Physics and Interdisciplinary Nanoscience Center, Universitaet Hamburg, Jungiusstrasse 9A, D-20355 Hamburg (Germany); Sidorenko, Anatoli S. [D. Ghitsu Institute of Electronic Engineering and Nanotechnologies ASM, Academiei Str. 3/3, MD2028 Kishinev (Moldova, Republic of); Tagirov, Lenar R. [Institut fuer Physik, Universitaet Augsburg, D-86159 Augsburg (Germany); Solid State Physics Department, Kazan Federal University, 420008 Kazan (Russian Federation)

2016-07-01

We fabricated a nanolayered hybrid superconductor-ferromagnet spin-valve structure, i.e. the superconducting transition temperature of this structure depends on its magnetic history. The observed spin-valve effect is based on the generation of the long range odd in frequency triplet component, arising from a non-collinear relative orientation of the constituent ferromagnetic layers. We investigated the effect both as a function of the sweep amplitude of the magnetic field, determining the magnetic history, and the applied transport current. Moreover, we demonstrate the possibility of switching the system from the normal o the superconducting state by applying field pulses, yielding an infinite magnetoresistance ratio.

Quantum infinite square well with an oscillating wall

International Nuclear Information System (INIS)

Glasser, M.L.; Mateo, J.; Negro, J.; Nieto, L.M.

2009-01-01

A linear matrix equation is considered for determining the time dependent wave function for a particle in a one-dimensional infinite square well having one moving wall. By a truncation approximation, whose validity is checked in the exactly solvable case of a linearly contracting wall, we examine the cases of a simple harmonically oscillating wall and a non-harmonically oscillating wall for which the defining parameters can be varied. For the latter case, we examine in closer detail the dependence on the frequency changes, and we find three regimes: an adiabatic behabiour for low frequencies, a periodic one for high frequencies, and a chaotic behaviour for an intermediate range of frequencies.

Semi-infinite photocarrier radiometric model for the characterization of semiconductor wafer

International Nuclear Information System (INIS)

Liu Xianming; Li Bincheng; Huang Qiuping

2010-01-01

The analytical expression is derived to describe the photocarrier radiometric (PCR) signal for a semi-infinite semiconductor wafer excited by a square-wave modulated laser. For comparative study, the PCR signals are calculated by the semi-infinite model and the finite thickness model with several thicknesses. The fitted errors of the electronic transport properties by semi-infinite model are analyzed. From these results it is evident that for thick samples or at high modulation frequency, the semiconductor can be considered as semi-infinite.

Infinite order quantum-gravitational correlations

Science.gov (United States)

Knorr, Benjamin

2018-06-01

A new approximation scheme for nonperturbative renormalisation group equations for quantum gravity is introduced. Correlation functions of arbitrarily high order can be studied by resolving the full dependence of the renormalisation group equations on the fluctuation field (graviton). This is reminiscent of a local potential approximation in O(N)-symmetric field theories. As a first proof of principle, we derive the flow equation for the ‘graviton potential’ induced by a conformal fluctuation and corrections induced by a gravitational wave fluctuation. Indications are found that quantum gravity might be in a non-metric phase in the deep ultraviolet. The present setup significantly improves the quality of previous fluctuation vertex studies by including infinitely many couplings, thereby testing the reliability of schemes to identify different couplings to close the equations, and represents an important step towards the resolution of the Nielsen identity. The setup further allows one, in principle, to address the question of putative gravitational condensates.

Elastic properties of graphite and interstitial defects

International Nuclear Information System (INIS)

Ayasse, J.-B.

1977-01-01

The graphite elastic constants C 33 and C 44 , reflecting the interaction of the graphitic planes, were experimentally measured as a function of irradiation and temperature. A model of non-central strength atomic interaction was established to explain the experimental results obtained. This model is valid at zero temperature. The temperature dependence of the elastic properties was analyzed. The influence of the elastic property variations on the specific heat of the lattice at very low temperature was investigated [fr

Supermarkets and unhealthy food marketing: An international comparison of the content of supermarket catalogues/circulars.

Science.gov (United States)

Charlton, Emma L; Kähkönen, Laila A; Sacks, Gary; Cameron, Adrian J

2015-12-01

Supermarket marketing activities have a major influence on consumer food purchases. This study aimed to assess and compare the contents of supermarket marketing circulars from a range of countries worldwide from an obesity prevention perspective. The contents of supermarket circulars from major supermarket chains in 12 non-random countries were collected and analysed over an eight week period from July to September 2014 (n=89 circulars with 12,563 food products). Circulars were largely English language and from countries representing most continents. Food products in 25 sub-categories were categorised as discretionary or non-discretionary (core) food or drinks based on the Australian Guide to Healthy Eating. The total number of products in each subcategory in the whole circular, and on front covers only, was calculated. Circulars from most countries advertised a high proportion of discretionary foods. The only exceptions were circulars from the Philippines (no discretionary foods) and India (11% discretionary food). Circulars from six countries advertised more discretionary foods than core foods. Front covers tended to include a much greater proportion of healthy products than the circulars overall. Supermarket circulars in most of the countries examined include a high percentage of discretionary foods, and therefore promote unhealthy eating behaviours that contribute to the global obesity epidemic. A clear opportunity exists for supermarket circulars to promote rather than undermine healthy eating behaviours of populations. Governments need to ensure that supermarket marketing is included as part of broader efforts to restrict unhealthy food marketing. Copyright © 2015 Elsevier Inc. All rights reserved.

Roadmap of Infinite Results

DEFF Research Database (Denmark)

Srba, Jiří

2002-01-01

This paper provides a comprehensive summary of equivalence checking results for infinite-state systems. References to the relevant papers will be updated continuously according to the development in the area. The most recent version of this document is available from the web-page http://www.brics.dk/~srba/roadmap....

Absorbed Power Minimization in Cellular Users with Circular Antenna Arrays

Science.gov (United States)

Christofilakis, Vasilis; Votis, Constantinos; Tatsis, Giorgos; Raptis, Vasilis; Kostarakis, Panos

2010-01-01

Nowadays electromagnetic pollution of non ionizing radiation generated by cellular phones concerns millions of people. In this paper the use of circular antenna array as a means of minimizing the absorbed power by cellular phone users is introduced. In particular, the different characteristics of radiation patterns produced by a helical conventional antenna used in mobile phones operating at 900 MHz and those produced by a circular antenna array, hypothetically used in the same mobile phones, are in detail examined. Furthermore, the percentage of decrement of the power absorbed in the head as a function of direction of arrival is estimated for the circular antenna array.

Targeting estimation of CCC-GARCH models with infinite fourth moments

DEFF Research Database (Denmark)

Pedersen, Rasmus Søndergaard

. In this paper we consider the large-sample properties of the variance targeting estimator for the multivariate extended constant conditional correlation GARCH model when the distribution of the data generating process has infinite fourth moments. Using non-standard limit theory we derive new results...... for the estimator stating that its limiting distribution is multivariate stable. The rate of consistency of the estimator is slower than √Τ (as obtained by the quasi-maximum likelihood estimator) and depends on the tails of the data generating process....

Non-hydrostatic semi-elastic hybrid-coordinate SISL extension of HIRLAM. Part II: numerical testing

Science.gov (United States)

Rõõm, Rein; Männik, Aarne; Luhamaa, Andres; Zirk, Marko

2007-10-01

The semi-implicit semi-Lagrangian (SISL), two-time-level, non-hydrostatic numerical scheme, based on the non-hydrostatic, semi-elastic pressure-coordinate equations, is tested in model experiments with flow over given orography (elliptical hill, mountain ridge, system of successive ridges) in a rectangular domain with emphasis on the numerical accuracy and non-hydrostatic effect presentation capability. Comparison demonstrates good (in strong primary wave generation) to satisfactory (in weak secondary wave reproduction in some cases) consistency of the numerical modelling results with known stationary linear test solutions. Numerical stability of the developed model is investigated with respect to the reference state choice, modelling dynamics of a stationary front. The horizontally area-mean reference temperature proves to be the optimal stability warrant. The numerical scheme with explicit residual in the vertical forcing term becomes unstable for cross-frontal temperature differences exceeding 30 K. Stability is restored, if the vertical forcing is treated implicitly, which enables to use time steps, comparable with the hydrostatic SISL.

A unified phenomenological model for non-elastic deformation of Type 316 stainless steel

International Nuclear Information System (INIS)

Schmidt, C.G.; Miller, A.K.

1981-01-01

A complete model is provided for the non-elastic deformation of unaged type 316 stainless steel. The fitting flexibility, breadth of application, and predictive capabilities of the model are demonstrated for a wide variety of data. Satisfactory descriptions are given of the steady-state and transient creep behaviour as well as the monotonic stress-strain behaviour from the yield stress to steady-state flow. These descriptions apply over a broad range of temperatures and strain rates for both solution annealed and 20% cold worked material. Furthermore, cyclic stress-strain curves, cyclic hysteresis loops, and stress relaxation data are shown to be well described for solution annealed material. (author)

Information Circulars

Energy Technology Data Exchange (ETDEWEB)

NONE

1973-09-10

Information circulars are published from time to time under the symbol INFCIRC/.. for the purpose of bringing matters of general interest to the attention of all Members of the Agency. A subject index to the circulars is presented overleaf. It covers all those published in the last five years (that is, since the beginning of 1968 and ending with INFCIRC/192), as well as others which, for one reason or another, are still considered to be of current rather than merely historical interest. Such circulars can be traced by reference to the indexes that were included in earlier revisions of the present document.

Information Circulars

International Nuclear Information System (INIS)

1973-01-01

Information circulars are published from time to time under the symbol INFCIRC/.. for the purpose of bringing matters of general interest to the attention of all Members of the Agency. A subject index to the circulars is presented overleaf. It covers all those published in the last five years (that is, since the beginning of 1968 and ending with INFCIRC/192), as well as others which, for one reason or another, are still considered to be of current rather than merely historical interest. Such circulars can be traced by reference to the indexes that were included in earlier revisions of the present document.

Conical Refraction of Elastic Waves by Anisotropic Metamaterials and Application for Parallel Translation of Elastic Waves.

Science.gov (United States)

Ahn, Young Kwan; Lee, Hyung Jin; Kim, Yoon Young

2017-08-30

Conical refraction, which is quite well-known in electromagnetic waves, has not been explored well in elastic waves due to the lack of proper natural elastic media. Here, we propose and design a unique anisotropic elastic metamaterial slab that realizes conical refraction for horizontally incident longitudinal or transverse waves; the single-mode wave is split into two oblique coupled longitudinal-shear waves. As an interesting application, we carried out an experiment of parallel translation of an incident elastic wave system through the anisotropic metamaterial slab. The parallel translation can be useful for ultrasonic non-destructive testing of a system hidden by obstacles. While the parallel translation resembles light refraction through a parallel plate without angle deviation between entry and exit beams, this wave behavior cannot be achieved without the engineered metamaterial because an elastic wave incident upon a dissimilar medium is always split at different refraction angles into two different modes, longitudinal and shear.

Interpretation of the quasi-elastic neutron scattering on PAA by rotational diffusion models

International Nuclear Information System (INIS)

Bata, L.; Vizi, J.; Kugler, S.

1974-10-01

First the most important data determined by other methods for para azoxy anisolon (PAA) are collected. This molecule makes a rotational oscillational motion around the mean molecular direction. The details of this motion can be determined by inelastic neutron scattering. Quasielastic neutron scattering measurements were carried out without orienting magnetic field on a time-of-flight facility with neutron beam of 4.26 meV. For the interpretation of the results two models, the spherical rotation diffusion model and the circular random walk model are investigated. The comparison shows that the circular random walk model (with N=8 sites, d=4A diameter and K=10 10 s -1 rate constant) fits very well with the quasi-elastic neutron scattering, while the spherical rotational diffusion model seems to be incorrect. (Sz.N.Z.)

Big bang in a universe with infinite extension

Energy Technology Data Exchange (ETDEWEB)

Groen, Oeyvind [Oslo College, Department of Engineering, PO Box 4, St Olavs Pl, 0130 Oslo (Norway); Institute of Physics, University of Oslo, PO Box 1048 Blindern, 0316 Oslo (Norway)

2006-05-01

How can a universe coming from a point-like big bang event have infinite spatial extension? It is shown that the relativity of simultaneity is essential in answering this question. Space is finite as defined by the simultaneity of one observer, but it may be infinite as defined by the simultaneity of all the clocks participating in the Hubble flow.

Big bang in a universe with infinite extension

International Nuclear Information System (INIS)

Groen, Oeyvind

2006-01-01

How can a universe coming from a point-like big bang event have infinite spatial extension? It is shown that the relativity of simultaneity is essential in answering this question. Space is finite as defined by the simultaneity of one observer, but it may be infinite as defined by the simultaneity of all the clocks participating in the Hubble flow

76 FR 60590 - Environmental Justice; Proposed Circular

Science.gov (United States)

2011-09-29

... oral presentations about the two proposed Circulars and allow attendees an opportunity to ask... of the comfort and safety of all attendees and the maximum seating capacity of meeting rooms, FTA... and non-traditional media, as well as digital media. Additional strategies to increase involvement of...

Effect of heat radiation in a Walter’s liquid B fluid over a stretching sheet with non-uniform heat source/sink and elastic deformation

Directory of Open Access Journals (Sweden)

A.K. Abdul Hakeem

2014-07-01

Full Text Available In this present article heat transfer in a Walter’s liquid B fluid over an impermeable stretching sheet with non-uniform heat source/sink, elastic deformation and radiation are reported. The basic boundary layer equations for momentum and heat transfer, which are non-linear partial differential equations, are converted into non-linear ordinary differential equations by means of similarity transformation. The dimensionless governing equations for this investigation are solved analytically using hyper geometric functions. The results are carried out for prescribed surface temperature (PST and prescribed power law surface heat flux (PHF. The effects of viscous dissipation, Prandtl number, Eckert number, heat source/sink parameter with elastic deformation and radiation are shown in the several plots and addressed.

Turnpike phenomenon and infinite horizon optimal control

CERN Document Server

Zaslavski, Alexander J

2014-01-01

This book is devoted to the study of the turnpike phenomenon and describes the existence of solutions for a large variety of infinite horizon optimal control classes of problems.  Chapter 1 provides introductory material on turnpike properties. Chapter 2 studies the turnpike phenomenon for discrete-time optimal control problems. The turnpike properties of autonomous problems with extended-value intergrands are studied in Chapter 3. Chapter 4 focuses on large classes of infinite horizon optimal control problems without convexity (concavity) assumptions. In Chapter 5, the turnpike results for a class of dynamic discrete-time two-player zero-sum game are proven. This thorough exposition will be very useful  for mathematicians working in the fields of optimal control, the calculus of variations, applied functional analysis, and infinite horizon optimization. It may also be used as a primary text in a graduate course in optimal control or as supplementary text for a variety of courses in other disciplines. Resea...

Elastic removal self-shielding factors for light and medium nuclides with strong-resonance scattering

International Nuclear Information System (INIS)

Nakagawa, Masayuki; Ishiguro, Yukio; Tokuno, Yukio.

1978-01-01

The self-shielding factors for elastic removal cross sections of light and medium weight nuclides were calculated for the parameter, σ 0 within the conventional concept of the group constant sets. The numerical study were performed for obtaining a simple and accurate method. The present results were compared with the exact values and the conventional ones, and shown to be remarkably improved. It became apparent that the anisotropy of the elastic scattering did not affect to the self-shielding factors though it did to the infinite dilution cross sections. With use of the present revised set, the neutron flux were calculated in an iron medium and in a prototype FBR and compared with those by the fine spectrum calculations and the conventional set. The present set showed the considerable improvement in the vicinity of the large resonance regions of sodium, iron and oxygen. (auth.)

Frequency Equations for the In-Plane Vibration of Circular Annular Disks

Directory of Open Access Journals (Sweden)

S. Bashmal

2010-01-01

Full Text Available This paper deals with the in-plane vibration of circular annular disks under combinations of different boundary conditions at the inner and outer edges. The in-plane free vibration of an elastic and isotropic disk is studied on the basis of the two-dimensional linear plane stress theory of elasticity. The exact solution of the in-plane equation of equilibrium of annular disk is attainable, in terms of Bessel functions, for uniform boundary conditions. The frequency equations for different modes can be obtained from the general solutions by applying the appropriate boundary conditions at the inner and outer edges. The presented frequency equations provide the frequency parameters for the required number of modes for a wide range of radius ratios and Poisson's ratios of annular disks under clamped, free, or flexible boundary conditions. Simplified forms of frequency equations are presented for solid disks and axisymmetric modes of annular disks. Frequency parameters are computed and compared with those available in literature. The frequency equations can be used as a reference to assess the accuracy of approximate methods.

Robust Consumption-Investment Problem on Infinite Horizon

Energy Technology Data Exchange (ETDEWEB)

Zawisza, Dariusz, E-mail: dariusz.zawisza@im.uj.edu.pl [Jagiellonian University in Krakow, Institute of Mathematics, Faculty of Mathematics and Computer Science (Poland)

2015-12-15

In our paper we consider an infinite horizon consumption-investment problem under a model misspecification in a general stochastic factor model. We formulate the problem as a stochastic game and finally characterize the saddle point and the value function of that game using an ODE of semilinear type, for which we provide a proof of an existence and uniqueness theorem for its solution. Such equation is interested on its own right, since it generalizes many other equations arising in various infinite horizon optimization problems.

Monoenergetic particle transport in a semi-infinite medium with reflection

International Nuclear Information System (INIS)

Ganapol, B.D.

1993-01-01

Next to neutron or photon transport in infinite geometry, particle transport in semi-infinite geometry is probably the most investigated transport problem. When the mean free path for particle interaction is small compared to the physical dimension of the scattering medium, the infinite or semi-infinite geometry assumption is reasonable for a variety of applications. These include nondestructive testing, photon transport in plant canopies, and inverse problems associated with well logging. Another important application of the transport solution in a semi-infinite medium is as a benchmark to which other more approximate methods can be compared. In this paper, the transport solution in a semi-infinite medium with both diffuse and specular reflection at the free surface is solved analytically and numerically evaluated. The approach is based on a little-known solution obtained by Sobelev for the problem with specular reflection, which itself originates from the classical albedo problem solution without reflection. Using Sobelev's solution as a partial Green's function, the exiting flux for diffuse reflection can be obtained. In this way, the exiting flux for a half-space with both constant diffuse and specular reflection coefficients is obtained for the first time. This expression can then be extended to the complex plane to obtain the interior flux as an inverse Laplace transform, which is numerically evaluated

Influence of structural parameter included in nonlocal rock mass model on stress concentration around circular tunnel

Science.gov (United States)

Lavrikov, SV; Mikenina, OA; Revuzhenko, AF

2018-03-01

A model of elastic body, including local curvature of elementary volume, is matched with a nonlocal model with a linear structural parameter in the differential approximation. The problem on deformation of rock mass around a circular cross section tunnel is solved numerically. The contours of the calculated stresses are plotted. It is shown that inclusion of local bends in the model results in expansion of influence zone of the tunnel and reduces stress concentration factor at the tunnel boundary.

Coupled thermal stress analysis of a hollow circular cylinder with transversely isotropic properties

International Nuclear Information System (INIS)

Tanigawa, Y.; Ootao, Y.

1987-01-01

If we shall analyze the thermal stress problems exactly in a transient state in continuum media, discussed with both the coupling and inertia effect, it has be shown that the thermomechanical coupling term shows a significant role than the inertia term for the common commercial alloys. In the present paper, we have considered the continuum medium with transversely isotropic material property, which has an isotropic property in r-θ plane, and analyzed the transient thermal stress problem of an infinitely long hollow circular cylinder due to an axisymmetrical partial heating. In order to get the thermal and thermoelastic fundamental differential equations separated in each field, we have introduced a perturbation technique. And then, we have carried out numerical calculations for several values of thermal and thermoelastic orthotropical parameters. (orig./GL)

Electromagnetic fields created by a macroparticle in an infinitely long and axisymmetric multilayer beam pipe

CERN Document Server

Mounet, N

2009-01-01

This paper aims at giving an as complete and detailed as possible derivation of the six electromagnetic field components created by an offset point charge travelling at any speed in an infinitely long circular multilayer beam pipe. Outcomes from this study are a novel and efficient matrix method for the field matching determination of all the constants involved in the field components, and the generalization to any azimuthal mode together with the final summation on all such modes in the impedance formulas. In particular the multimode direct space-charge impedances (both longitudinal and transverse) are given, as well as the wall impedance to any order of precision. New quadrupolar terms for the transverse wall impedance are found, which look negligible in the ultrarelativistic case but might be of significance for low-energy beams. In principle from this analysis the electromagnetic fields created by any particular source, with a finite transverse shape, can then be computed using convolutions.

God, Evil, and Infinite Value

Directory of Open Access Journals (Sweden)

Marshall Naylor

2018-01-01

Full Text Available Prominent approaches to the problems of evil assume that even if the Anselmian God exists, some worlds are better than others, all else being equal. But the assumptions that the Anselmian God exists and that some worlds are better than others cannot be true together. One description, by Mark Johnston and Georg Cantor, values God’s existence as exceeding any transfinite cardinal value. For any finite or infinite amount of goodness in any possible world, God’s value infinitely exceeds that amount. This conception is not obviously inconsistent with the Anselmian God. As a result, the prominent approaches to the problems of evil are mistaken. The elimination of evil does not, in fact, improve the value of any world as commonly thought. Permitting evil does not, in fact, diminish the value of any world as commonly thought.

Information Circulars

International Nuclear Information System (INIS)

1965-01-01

Information circulars are published from time to time under the symbol INFCIRC/. for the purpose of bringing matters of general interest to the attention of all Members of the Agency. A list of the circulars that were current on 31 December 1964 is given, followed by an index to their subject matter.

Information circulars

International Nuclear Information System (INIS)

1992-08-01

The document summarizes the Information Circulars published by the IAEA for the purpose of bringing matters of general interest to the attention of all Members of the Agency. This revision contains INFCIRCs published up to mid-August 1992. A complete numerical lift of Information Circulars with their titles is reproduced in an Annex

Information Circulars

Energy Technology Data Exchange (ETDEWEB)

NONE

1965-01-18

Information circulars are published from time to time under the symbol INFCIRC/. for the purpose of bringing matters of general interest to the attention of all Members of the Agency. A list of the circulars that were current on 31 December 1964 is given, followed by an index to their subject matter.

PHYSICAL FIELDS OF CIRCULAR CYLINDRICAL PIEZOCERAMIC RECEIVER IN PRESENCE OF A FLAT ACOUSTIC SOFT SCREEN

Directory of Open Access Journals (Sweden)

A. V. Derepa

2017-01-01

Full Text Available System in the form of a circular cylindrical piezoceramic transducer near a flat acoustic screen was analyzed. The aim of the work was to solve the problem of receiving plane sound waves by «cylindrical piezoceramic transducer – flat acoustically soft screen» system.Considered system was characterized by a violation of the radial symmetry of the radiation load of the transducer while maintaining the radial symmetry of the electric load. At the same time, the energy perceived by the system under consideration is distributed between all modes of oscillation of the transducer, while the conversion of mechanical energy into electric is realized only at zero mole of oscillations.Special attention was paid to the method of coupled fields in multiply connected domains using the imaging method. The design model of the «transducer–creen» system was formulated taking into account the interaction of acoustic, mechanical and electric fields in the process of energy conversion, the interaction of a cylindrical transducer with a flat screen and the interaction of a converter with elastic media outside and inside it. The physical fields of the system under consideration were determined by following solutions: the wave equation; equations of motion of thin piezoceramic cylindrical shells in displacements; equations of stimulated electrostatics for piezoceramics for given boundary conditions, conditions for coupling fields at interfaces and electrical conditions.A general conclusion was made concerning solving of an infinite system of linear algebraic equations with respect to the unknown coefficients of the expansion of the fields. As an example of the application of the obtained relations, a calculation was made and an analysis of the dependences of the electric fields of the system under consideration for various parameters of its construction on the direction of arrival on the plane wave system was conducted.

Simplified description of out-of-plane waves in thin annular elastic plates

DEFF Research Database (Denmark)

Zadeh, Maziyar Nesari; Sorokin, Sergey

2013-01-01

Dispersion relations are derived for the out-of-plane wave propagation in planar elastic plates with constant curvature using the classical Kirchhoff thin plate theory. The dispersion diagrams and the mode shapes are compared with their counterparts for a straight plate strip and the role...... of curvature is assessed for plates with unconstrained edges. Elementary Bernoulli–Euler theory for a beam of rectangular cross-section with the circular shape of its axis is also employed to analyze the wave guide properties of this structure in its out-of-plane deformation. The applicability range...... of the elementary beam theory is validated. The wave finite element method in the formulation of the three-dimensional elasticity theory is used to ensure that the comparison of dispersion diagrams is performed in the frequency range, where the classical thin plate theory is valid. Thus, the paper summarizes...

An infinite set of Ward identities for adiabatic modes in cosmology

International Nuclear Information System (INIS)

Hinterbichler, Kurt; Hui, Lam; Khoury, Justin

2014-01-01

We show that the correlation functions of any single-field cosmological model with constant growing-modes are constrained by an infinite number of novel consistency relations, which relate N+1-point correlation functions with a soft-momentum scalar or tensor mode to a symmetry transformation on N-point correlation functions of hard-momentum modes. We derive these consistency relations from Ward identities for an infinite tower of non-linearly realized global symmetries governing scalar and tensor perturbations. These symmetries can be labeled by an integer n. At each order n, the consistency relations constrain — completely for n = 0,1, and partially for n ≥ 2 — the q n behavior of the soft limits. The identities at n = 0 recover Maldacena's original consistency relations for a soft scalar and tensor mode, n = 1 gives the recently-discovered conformal consistency relations, and the identities for n ≥ 2 are new. As a check, we verify directly that the n = 2 identity is satisfied by known correlation functions in slow-roll inflation

Information circulars

International Nuclear Information System (INIS)

1997-02-01

The document summarizes the Information Circulars published by the IAEA for the purpose of bringing matters of general interest to the attention of all Member States. This revision contains INFCIRCs published up to February 1997, grouped by field of activity. A complete list of information circulars in numerical order is given in an annex

Guiding spoof surface plasmon polaritons by infinitely thin grooved metal strip

Directory of Open Access Journals (Sweden)

Xiang Wan

2014-04-01

Full Text Available In this paper, the propagation characteristics of spoof surface plasmon polaritons (SPPs on infinitely thin corrugated metal strips are theoretically analyzed. Compared with the situations of infinitely thick lateral thickness, the infinitely thin lateral thickness leads to lower plasma frequency according to the analyses. The propagation lengths and the binding capacity of the spoof SPPs are evaluated based on the derived dispersion equation. The effects of different lateral thicknesses are also investigated. At the end, a surface wave splitter is presented using infinitely thin corrugated metal strip. Other functional planar or flexible devices can also be designed using these metal strips in microwave or terahertz regimes.

An Infinite Sequence of Full AFL-Structures, Each of Which Possesses an Infinite Hierarchy

NARCIS (Netherlands)

Asveld, P.R.J.

1999-01-01

We investigate different sets of operations on languages which results in corresponding algebraic structures, viz.\\ in different types of full AFL's (full Abstract Family of Languages). By iterating control on ETOL-systems we show that there exists an infinite sequence ${\\cal C}_m$ ($m\\geq1$) of

An Infinite Sequence of Full AFL-structures, Each of Which Possesses an Infinite Hierarchy

NARCIS (Netherlands)

Asveld, P.R.J.; Martin-Vide, C.; Mitrana, V.

2001-01-01

We investigate different sets of operations on languages which results in corresponding algebraic structures, viz.\\ in different types of full AFL's (full Abstract Family of Languages). By iterating control on ETOL-systems we show that there exists an infinite sequence ${\\cal C}_m$ ($m\\geq1$) of

An infinite-dimensional weak KAM theory via random variables

KAUST Repository

Gomes, Diogo A.

2016-08-31

We develop several aspects of the infinite-dimensional Weak KAM theory using a random variables\\' approach. We prove that the infinite-dimensional cell problem admits a viscosity solution that is a fixed point of the Lax-Oleinik semigroup. Furthermore, we show the existence of invariant minimizing measures and calibrated curves defined on R.

An infinite-dimensional weak KAM theory via random variables

KAUST Repository

Gomes, Diogo A.; Nurbekyan, Levon

2016-01-01

We develop several aspects of the infinite-dimensional Weak KAM theory using a random variables' approach. We prove that the infinite-dimensional cell problem admits a viscosity solution that is a fixed point of the Lax-Oleinik semigroup. Furthermore, we show the existence of invariant minimizing measures and calibrated curves defined on R.

Information circulars

International Nuclear Information System (INIS)

1994-08-01

Information circulars are published from time to time under the symbol INFCIRC/... for the purpose of bringing matters of general interest to the attention of all Members of the Agency. The present revision contains INFCIRCs published up to mid-August 1994. A complete numerical list of information circulars is reproduced with their titles in the Annex

Information circulars

International Nuclear Information System (INIS)

2002-05-01

Information circulars are published from time to time under the symbol INFCIRC/... for the purpose of bringing matters of general interest to the attention of all Members of the Agency. The present revision contains INFCIRCs published up to the end of April 2002. A complete numerical list of information circulars is reproduced with their titles in the Annex

Information circulars

International Nuclear Information System (INIS)

1999-06-01

The document summarizes the Information Circulars published by the IAEA for the purpose of bringing matters of general interest to the attention of all Member States. This revision contains INFCIRCs published up to the end of May 1999, grouped by field of activity. A complete list of information circulars in numerical order is given in an annex

Information Circulars

International Nuclear Information System (INIS)

1966-01-01

Information circulars are published from time to time under the symbol INFCIRC/. . . . for the purpose of bringing matters of general interest to the attention of all Members of the Agency. A list of the circulars that were current or on the press on 15 May 1966 is given, followed by an index to their subject matter.

Information Circulars

Energy Technology Data Exchange (ETDEWEB)

NONE

1966-06-10

Information circulars are published from time to time under the symbol INFCIRC/. . . . for the purpose of bringing matters of general interest to the attention of all Members of the Agency. A list of the circulars that were current or on the press on 15 May 1966 is given, followed by an index to their subject matter.

Transposable elements and circular DNAs

KAUST Repository

Mourier, Tobias

2016-09-26

Circular DNAs are extra-chromosomal fragments that become circularized by genomic recombination events. We have recently shown that yeast LTR elements generate circular DNAs through recombination events between their flanking long terminal repeats (LTRs). Similarly, circular DNAs can be generated by recombination between LTRs residing at different genomic loci, in which case the circular DNA will contain the intervening sequence. In yeast, this can result in gene copy number variations when circles contain genes and origins of replication. Here, I speculate on the potential and implications of circular DNAs generated through recombination between human transposable elements.

Transposable elements and circular DNAs

KAUST Repository

Mourier, Tobias

2016-01-01

Circular DNAs are extra-chromosomal fragments that become circularized by genomic recombination events. We have recently shown that yeast LTR elements generate circular DNAs through recombination events between their flanking long terminal repeats (LTRs). Similarly, circular DNAs can be generated by recombination between LTRs residing at different genomic loci, in which case the circular DNA will contain the intervening sequence. In yeast, this can result in gene copy number variations when circles contain genes and origins of replication. Here, I speculate on the potential and implications of circular DNAs generated through recombination between human transposable elements.

A New Limit on CMB Circular Polarization from SPIDER

Energy Technology Data Exchange (ETDEWEB)

Nagy, J. M.; Ade, P. A. R.; Amiri, M.; Benton, S. J.; Bergman, A. S.; Bihary, R.; Bock, J. J.; Bond, J. R.; Bryan, S. A.; Chiang, H. C.; Contaldi, C. R.; Doré, O.; Duivenvoorden, A. J.; Eriksen, H. K.; Farhang, M.; Filippini, J. P.; Fissel, L. M.; Fraisse, A. A.; Freese, K.; Galloway, M.; Gambrel, A. E.; Gandilo, N. N.; Ganga, K.; Gudmundsson, J. E.; Halpern, M.; Hartley, J.; Hasselfield, M.; Hilton, G.; Holmes, W.; Hristov, V. V.; Huang, Z.; Irwin, K. D.; Jones, W. C.; Kuo, C. L.; Kermish, Z. D.; Li, S.; Mason, P. V.; Megerian, K.; Moncelsi, L.; Morford, T. A.; Netterfield, C. B.; Nolta, M.; Padilla, I. L.; Racine, B.; Rahlin, A. S.; Reintsema, C.; Ruhl, J. E.; Runyan, M. C.; Ruud, T. M.; Shariff, J. A.; Soler, J. D.; Song, X.; Trangsrud, A.; Tucker, C.; Tucker, R. S.; Turner, A. D.; List, J. F. Van Der; Weber, A. C.; Wehus, I. K.; Wiebe, D. V.; Young, E. Y.

2017-08-01

We present a new upper limit on CMB circular polarization from the 2015 flight of SPIDER, a balloon-borne telescope designed to search for $B$-mode linear polarization from cosmic inflation. Although the level of circular polarization in the CMB is predicted to be very small, experimental limits provide a valuable test of the underlying models. By exploiting the non-zero circular-to-linear polarization coupling of the HWP polarization modulators, data from SPIDER's 2015 Antarctic flight provides a constraint on Stokes $V$ at 95 and 150 GHz from $33<\\ell<307$. No other limits exist over this full range of angular scales, and SPIDER improves upon the previous limit by several orders of magnitude, providing 95% C.L. constraints on $\\ell (\\ell+1)C_{\\ell}^{VV}/(2\\pi)$ ranging from 141 $\\mu K ^2$ to 203 $\\mu K ^2$ at 150 GHz for a thermal CMB spectrum. As linear CMB polarization experiments become increasingly sensitive, the techniques described in this paper can be applied to obtain stronger constraints on circular polarization.

OBSERVING LYAPUNOV EXPONENTS OF INFINITE-DIMENSIONAL DYNAMICAL SYSTEMS.

Science.gov (United States)

Ott, William; Rivas, Mauricio A; West, James

2015-12-01

Can Lyapunov exponents of infinite-dimensional dynamical systems be observed by projecting the dynamics into ℝ N using a 'typical' nonlinear projection map? We answer this question affirmatively by developing embedding theorems for compact invariant sets associated with C 1 maps on Hilbert spaces. Examples of such discrete-time dynamical systems include time- T maps and Poincaré return maps generated by the solution semigroups of evolution partial differential equations. We make every effort to place hypotheses on the projected dynamics rather than on the underlying infinite-dimensional dynamical system. In so doing, we adopt an empirical approach and formulate checkable conditions under which a Lyapunov exponent computed from experimental data will be a Lyapunov exponent of the infinite-dimensional dynamical system under study (provided the nonlinear projection map producing the data is typical in the sense of prevalence).

Stresses and elastic constants of crystalline sodium, from molecular dynamics

International Nuclear Information System (INIS)

Schiferl, S.K.

1985-02-01

The stresses and the elastic constants of bcc sodium are calculated by molecular dynamics (MD) for temperatures to T = 340K. The total adiabatic potential of a system of sodium atoms is represented by pseudopotential model. The resulting expression has two terms: a large, strictly volume-dependent potential, plus a sum over ion pairs of a small, volume-dependent two-body potential. The stresses and the elastic constants are given as strain derivatives of the Helmholtz free energy. The resulting expressions involve canonical ensemble averages (and fluctuation averages) of the position and volume derivatives of the potential. An ensemble correction relates the results to MD equilibrium averages. Evaluation of the potential and its derivatives requires the calculation of integrals with infinite upper limits of integration, and integrand singularities. Methods for calculating these integrals and estimating the effects of integration errors are developed. A method is given for choosing initial conditions that relax quickly to a desired equilibrium state. Statistical methods developed earlier for MD data are extended to evaluate uncertainties in fluctuation averages, and to test for symmetry. 45 refs., 10 figs., 4 tabs

Infinite games and $sigma$-porosity

Czech Academy of Sciences Publication Activity Database

Doležal, Martin; Preiss, D.; Zelený, M.

2016-01-01

Roč. 215, č. 1 (2016), s. 441-457 ISSN 0021-2172 Institutional support: RVO:67985840 Keywords : infinite games Subject RIV: BA - General Mathematics Impact factor: 0.796, year: 2016 http://link.springer.com/article/10.1007%2Fs11856-016-1383-9

Analysis of infinite dimensional diffusions

NARCIS (Netherlands)

Maas, J.

2009-01-01

Stochastic processes in infinite dimensional state spaces provide a mathematical description of various phenomena in physics, population biology, finance, and other fields of science. Several aspects of these processes have been studied in this thesis by means of new analytic methods. Firstly,

Static deformation of an orthotropic elastic layered medium due to a ...

African Journals Online (AJOL)

Closed-form analytic expressions for the deformation field at any point of a homogeneous, orthotropic, homogeneous elastic layer interfacing differently to a base due to non-uniform discontinuity (slip) along a very long strike-slip fault situated in the orthotropic elastic layer have been obtained. Four non-uniform slip profiles: ...

Numerical study of pressure drop and heat transfer from circular and cam-shaped tube bank in cross-flow of nanofluid

International Nuclear Information System (INIS)

Mirabdolah Lavasani, Arash; Bayat, Hamidreza

2016-01-01

Highlights: • Flow around non-circular and circular shaped tube bank is studied. • Effect of using Al_2O_3-water nanofluid on flow and heat transfer is discussed. • Tubes are with in-line and staggered arrangement. • Pressure drop of non-circular tube is noticeably lower that circular tube. - Abstract: Flow and heat transfer of nanofluid inside circular and cam-shaped tube bank is studied numerically. Reynolds number for cam-shaped tube bank is defined based on equivalent diameter of circular tube and varies in range of 100 ⩽ Re_D ⩽ 400. Nanofluid is made by adding Al_2O_3 nanoparticle with volume fraction of 1–7% to pure water. Results show using nanofluid results in higher heat transfer rate for both circular tube bank and cam-shaped tube bank. Also, staggered arrangement has higher heat transfer for both circular and cam-shaped tube bank. Pressure drop from cam-shaped tube bank is substantially lower than circular tube bank for all range of Reynolds number and volume fraction.

Dynamic ASXL1 Exon Skipping and Alternative Circular Splicing in Single Human Cells.

Directory of Open Access Journals (Sweden)

Winston Koh

Full Text Available Circular RNAs comprise a poorly understood new class of noncoding RNA. In this study, we used a combination of targeted deletion, high-resolution splicing detection, and single-cell sequencing to deeply probe ASXL1 circular splicing. We found that efficient circular splicing required the canonical transcriptional start site and inverted AluSx elements. Sequencing-based interrogation of isoforms after ASXL1 overexpression identified promiscuous linear splicing between all exons, with the two most abundant non-canonical linear products skipping the exons that produced the circular isoforms. Single-cell sequencing revealed a strong preference for either the linear or circular ASXL1 isoforms in each cell, and found the predominant exon skipping product is frequently co-expressed with its reciprocal circular isoform. Finally, absolute quantification of ASXL1 isoforms confirmed our findings and suggests that standard methods overestimate circRNA abundance. Taken together, these data reveal a dynamic new view of circRNA genesis, providing additional framework for studying their roles in cellular biology.

Automated Analysis of Infinite Scenarios

DEFF Research Database (Denmark)

Buchholtz, Mikael

2005-01-01

The security of a network protocol crucially relies on the scenario in which the protocol is deployed. This paper describes syntactic constructs for modelling network scenarios and presents an automated analysis tool, which can guarantee that security properties hold in all of the (infinitely many...

Identification of Circular RNAs From the Parental Genes Involved in Multiple Aspects of Cellular Metabolism in Barley

Directory of Open Access Journals (Sweden)

Behrooz eDarbani

2016-06-01

Full Text Available RNA circularization made by head-to-tail back-splicing events is involved in the regulation of gene expression from transcriptional to post-translational levels. By exploiting RNA-Seq data and down-stream analysis, we shed light on the importance of circular RNAs in plants. The results introduce circular RNAs as novel interactors in the regulation of gene expression in plants and imply the comprehensiveness of this regulatory pathway by identifying circular RNAs for a diverse set of genes. These genes are involved in several aspects of cellular metabolism as hormonal signaling, intracellular protein sorting, carbohydrate metabolism and cell-wall biogenesis, respiration, amino acid biosynthesis, transcription and translation, and protein ubiquitination. Additionally, these parental loci of circular RNAs, from both nuclear and mitochondrial genomes, encode for different transcript classes including protein coding transcripts, microRNA, rRNA, and long non-coding/microprotein coding RNAs. The results shed light on the mitochondrial exonic circular RNAs and imply the importance of circular RNAs for regulation of mitochondrial genes. Importantly, we introduce circular RNAs in barley and elucidate their cellular-level alterations across tissues and in response to micronutrients iron and zinc. In further support of circular RNAs' functional roles in plants, we report several cases where fluctuations of circRNAs do not correlate with the levels of their parental-loci encoded linear transcripts.Keywords: circular RNAs, coding and non-coding transcripts, leaves, seeds, transfer cells, micronutrients, mitochondria

The local response of elastic tubes and shells to spherical pressure pulse loading

International Nuclear Information System (INIS)

Thompson, J.J.; Holy, Z.J.

1977-01-01

This paper develops a formulation and numerical solution technique for calculating the peak transient stresses developed in tubes or shells with external and internal acoustic media, as a result of shock loadings which may be represented as originating from external or internal point symmetric or dipole sources. The field of application is intended to be the local peak response of the cylindrical fuel cans, core barrels, pressure vessels, pipes and containment shells of Nuclear Reactor Technology, subjected to transient pressure shock loadings for a variety of operational or accident conditions, which cannot adequately be described as one dimensional plane shocks, for which elastic shell responses have been presented by other workers. The work reported here concerns the basic problem of an infinite static fluid filled hollow cylinder of arbitrary thickness, in an infinite static fluid medium, with a source at an arbitrary internal or external radial location. An acoustic model is used, with acoustic damping due to radiation as the only possible damping mechanism. The formulation and solution technique is based on the availability of the multi-dimensional Fast Fourier Transform algorithm. The basic result is the representation, in cylindrical co-ordinates, of the two dimensional (time and axial co-ordinate) Fourier Transform of the infinite medium frequency response function for outgoing waves from a point symmetrical source, as a series of azimuthal Fourier harmonics, from which the result for a dipole source of arbitrary orientation follows. Where possible numerical results will be presented

Activity coefficients at infinite dilution of hydrocarbons in glycols: Experimental data and thermodynamic modeling with the GCA-EoS

International Nuclear Information System (INIS)

González Prieto, Mariana; Williams-Wynn, Mark D.; Bahadur, Indra; Sánchez, Francisco A.; Mohammadi, Amir H.

2017-01-01

Highlights: • Experimental infinite dilution activity coefficients of hydrocarbons in glycols. • Inverse gas-liquid chromatography technique. • Solutes investigated include n-alkanes, 1-alkenes, and cycloalkanes. • Highly non-ideal systems are modeled with the GCA-EoS. - Abstract: The infinite dilution activity coefficients for 12 non-polar hydrocarbon solutes in the solvents, monoethylene and diethylene glycol, were measured using the gas-liquid chromatography technique. Pre-saturation of the carrier gas was required to avoid solvent loss from the chromatographic column during the measurements that were carried out at T = (303.15, 313.15 and 323.15) K for monoethylene glycol and at T = (304.15, 313.15 and 323.15) K for diethylene glycol. The solutes investigated include n-alkanes, 1-alkenes, and cycloalkanes. The new data are compared with the highly scattered data that is available in the open literature. Finally, these highly non-ideal systems are modeled with the GCA-EoS.

Generalized non-linear Schroedinger hierarchy

International Nuclear Information System (INIS)

Aratyn, H.; Gomes, J.F.; Zimerman, A.H.

1994-01-01

The importance in studying the completely integrable models have became evident in the last years due to the fact that those models present an algebraic structure extremely rich, providing the natural scenery for solitons description. Those models can be described through non-linear differential equations, pseudo-linear operators (Lax formulation), or a matrix formulation. The integrability implies in the existence of a conservation law associated to each of degree of freedom. Each conserved charge Q i can be associated to a Hamiltonian, defining a time evolution related to to a time t i through the Hamilton equation ∂A/∂t i =[A,Q i ]. Particularly, for a two-dimensions field theory, infinite degree of freedom exist, and consequently infinite conservation laws describing the time evolution in space of infinite times. The Hamilton equation defines a hierarchy of models which present a infinite set of conservation laws. This paper studies the generalized non-linear Schroedinger hierarchy

Polynomial sequences generated by infinite Hessenberg matrices

Directory of Open Access Journals (Sweden)

Verde-Star Luis

2017-01-01

Full Text Available We show that an infinite lower Hessenberg matrix generates polynomial sequences that correspond to the rows of infinite lower triangular invertible matrices. Orthogonal polynomial sequences are obtained when the Hessenberg matrix is tridiagonal. We study properties of the polynomial sequences and their corresponding matrices which are related to recurrence relations, companion matrices, matrix similarity, construction algorithms, and generating functions. When the Hessenberg matrix is also Toeplitz the polynomial sequences turn out to be of interpolatory type and we obtain additional results. For example, we show that every nonderogative finite square matrix is similar to a unique Toeplitz-Hessenberg matrix.

A numerical model for etching through a circular hole

International Nuclear Information System (INIS)

Rath, P; Chai, J C; Zheng, H; Lam, Y C; Murukeshan, V M

2006-01-01

A numerical model based on the total concentration of etchant is proposed to model the wet chemical etching through a circular hole. The reaction at the etchant-substrate interface is assumed to be infinitely fast i.e. etching is controlled by the diffusion of etchant to the interface. The proposed model is based on a fixed-grid approach analogous to the enthalpy method. The total concentration of etchant is the sum of the unreacted etchant concentration and the reacted etchant concentration. The reacted concentration of etchant is a measure of the etchfront position during etching. The governing mass diffusion equation based on the total concentration of etchant includes the interface condition. The etchfront position is found implicitly using the proposed approach. The computational domain is fixed, which includes the whole etchant and substrate domain including the mask region. For demonstration purposes, the finite volume method is used to solve the governing mass diffusion equation with prescribed initial and boundary conditions. The effect of mask thickness and initial etchant concentration on the shape evolution of etchfront is studied

Non-resonant energy harvester with elastic constraints for low rotating frequencies

Science.gov (United States)

Machado, Sebastián P.; Febbo, Mariano; Gatti, Claudio D.; Ramirez, José M.

2017-11-01

This paper presents a non-resonant piezoelectric energy harvester (PEH) which is designed to capture energy from low frequency rotational vibration. The proposed device works out of the plane of rotation where the motion of a mass-spring system is transferred to a piezoelectric layer with the intention to generate energy to power wireless structural monitoring systems or sensors. The mechanical structure is formed by two beams with rigid and elastic boundary conditions at the clamped end. On the free boundaries, heavy masses connected by a spring are placed in order to increase voltage generation and diminish the natural frequency. A mathematical framework and the equations governing the energy-harvesting system are presented. Numerical simulations and experimental verifications are performed for different rotation speeds ranging from 0.7 to 2.5 Hz. An output power of 125 μW is obtained for maximum rotating frequency demonstrating that the proposed design can collect enough energy for the suggested application.

Modeling radio circular polarization in the Crab nebula

Science.gov (United States)

Bucciantini, N.; Olmi, B.

2018-03-01

In this paper, we present, for the first time, simulated maps of the circularly polarized synchrotron emission from the Crab nebula, using multidimensional state of the art models for the magnetic field geometry. Synchrotron emission is the signature of non-thermal emitting particles, typical of many high-energy astrophysical sources, both Galactic and extragalactic ones. Its spectral and polarization properties allow us to infer key information on the particles distribution function and magnetic field geometry. In recent years, our understanding of pulsar wind nebulae has improved substantially thanks to a combination of observations and numerical models. A robust detection or non-detection of circular polarization will enable us to discriminate between an electron-proton plasma and a pair plasma, clarifying once for all the origin of the radio emitting particles, setting strong constraints on the pair production in pulsar magnetosphere, and the role of turbulence in the nebula. Previous attempts at measuring the circular polarization have only provided upper limits, but the lack of accurate estimates, based on reliable models, makes their interpretation ambiguous. We show here that those results are above the expected values, and that current polarimetric techniques are not robust enough for conclusive result, suggesting that improvements in construction and calibration of next generation radio facilities are necessary to achieve the desired sensitivity.

Free vibration analysis of a rotary smart two directional functionally graded piezoelectric material in axial symmetry circular nanoplate

Science.gov (United States)

Mahinzare, Mohammad; Ranjbarpur, Hosein; Ghadiri, Majid

2018-02-01

In this article, free vibration of a rotating circular nanoplate made of two directional functionally graded piezo materials (two directional FGPM) is modeled based on the first shear deformation theory (FSDT). Based on the power-law model, electro-elastic properties of two directional FGP rotating circular nanoplates are supposed to change continuously along the thickness and radius. Employing the modified couple stress theory, the small size effect of the equations of the plate is considered. The governing equations of the first shear deformation theory (FSDT) for the studied plate are obtained based on Hamilton's principle; these equations are solved using differential quadrature method (DQM). It is shown that the vibration behavior of the plate is significantly affected by angular velocity, external electric voltage, size dependency and power-law index (thickness and radial directions).

Information circulars

International Nuclear Information System (INIS)

1987-06-01

The document summarizes the information circulars published by the IAEA for the purpose of bringing matters of general interest to the attention of all Members of the Agency. In the main body of the document only those documents which are regarded as likely to be of current interest are listed. A complete numerical list of information circulars with their titles is reproduced in the Annex

[Integrated evaluation of circular agriculture system: a life cycle perspective].

Science.gov (United States)

Liang, Long; Chen, Yuan-Quan; Gao, Wang-Sheng

2010-11-01

For the point of view that recycling economy system is one of ways to achieve the low-carbon economy, we have made an evaluation on a typical circular agriculture duck industry in Hunan Province, China, through improving the framework of life cycle assessment (LCA). The analysis indicated that the consumption of non-renewable resources, land and water were 48.629 MJ, 2.36 m2 and 1 321.41 kg, while the potential greenhouse gas (GHGs), acidification, eutrophication, human toxicity, freshwater ecotoxicity and terrestrial ecotoxicity were 11 543.26 g (CO2 eq), 52.36g (SO2eq), 25.83g (PO4eq), 1.26, 60.74 and 24.65 g (1,4-DCBeq), respectively. The potential damage of aquatic eutrophication, freshwater ecotoxicity and terrestrial ecotoxicity was more serious than that of GHGs. Main results were following: i. the circular agricultural chain promoted the principle of "moderate circulation", which based on the traditional production methods; ii. circular agriculture could not blindly pursue low carbon development. Instead, soil and biological carbon sequestration should be considered, in addition to reducing carbon emissions; iii. circular economy and circular agriculture should take other potential environmental impacts into account such as acidification, eutrophication and ecotoxicity,with the exception to carbon emissions,to developed integrated system assessment; iv. LCA could provide a comprehensive assessment of circular agriculture, and it was worth of further study.

Agravity up to infinite energy

Energy Technology Data Exchange (ETDEWEB)

Salvio, Alberto [CERN, Theoretical Physics Department, Geneva (Switzerland); Strumia, Alessandro [Dipartimento di Fisica, Universita di Pisa (Italy); INFN, Pisa (Italy)

2018-02-15

The self-interactions of the conformal mode of the graviton are controlled, in dimensionless gravity theories (agravity), by a coupling f{sub 0} that is not asymptotically free. We show that, nevertheless, agravity can be a complete theory valid up to infinite energy. When f{sub 0} grows to large values, the conformal mode of the graviton decouples from the rest of the theory and does not hit any Landau pole provided that scalars are asymptotically conformally coupled and all other couplings approach fixed points. Then agravity can flow to conformal gravity at infinite energy. We identify scenarios where the Higgs mass does not receive unnaturally large physical corrections. We also show a useful equivalence between agravity and conformal gravity plus two extra conformally coupled scalars, and we give a simpler form for the renormalization group equations of dimensionless couplings as well as of massive parameters in the presence of the most general matter sector. (orig.)

Infinite symmetry in the quantum Hall effect

Directory of Open Access Journals (Sweden)

Lütken C.A.

2014-04-01

Full Text Available The new states of matter and concomitant quantum critical phenomena revealed by the quantum Hall effect appear to be accompanied by an emergent modular symmetry. The extreme rigidity of this infinite symmetry makes it easy to falsify, but two decades of experiments have failed to do so, and the location of quantum critical points predicted by the symmetry is in increasingly accurate agreement with scaling experiments. The symmetry severely constrains the structure of the effective quantum field theory that encodes the low energy limit of quantum electrodynamics of 1010 charges in two dirty dimensions. If this is a non-linear σ-model the target space is a torus, rather than the more familiar sphere. One of the simplest toroidal models gives a critical (correlation length exponent that agrees with the value obtained from numerical simulations of the quantum Hall effect.

Instanton Operators and the Higgs Branch at Infinite Coupling

CERN Document Server

Cremonesi, Stefano; Hanany, Amihay; Mekareeya, Noppadol

2017-01-01

The richness of 5d $\\mathcal{N}=1$ theories with a UV fixed point at infinite coupling is due to the existence of local disorder operators known as instanton operators. By considering the Higgs branch of $SU(2)$ gauge theories with $N_f \\leq 7$ flavours at finite and infinite coupling, we write down the explicit chiral ring relations between instanton operators, the glueball superfield and mesons. Exciting phenomena appear at infinite coupling: the glueball superfield is no longer nilpotent and the classical chiral ring relations are quantum corrected by instanton operators bilinears. We also find expressions for the dressing of instanton operators of arbitrary charge. The same analysis is performed for $USp(2k)$ with an antisymmetric hypermultiplet and pure $SU(N)$ gauge theories.

Instanton operators and the Higgs branch at infinite coupling

Energy Technology Data Exchange (ETDEWEB)

Cremonesi, Stefano [Department of Mathematics, King’s College London,The Strand, London WC2R 2LS (United Kingdom); Ferlito, Giulia; Hanany, Amihay [Theoretical Physics Group, Imperial College London,Prince Consort Road, London, SW7 2AZ (United Kingdom); Mekareeya, Noppadol [Theory Division, Physics Department, CERN,CH-1211, Geneva 23 (Switzerland)

2017-04-10

The richness of 5d N=1 theories with a UV fixed point at infinite coupling is due to the existence of local disorder operators known as instanton operators. By considering the Higgs branch of SU(2) gauge theories with N{sub f}≤7 flavours at finite and infinite coupling, we write down the explicit chiral ring relations between instanton operators, the glueball superfield and mesons. Exciting phenomena appear at infinite coupling: the glueball superfield is no longer nilpotent and the classical chiral ring relations are quantum corrected by instanton operators bilinears. We also find expressions for the dressing of instanton operators of arbitrary charge. The same analysis is performed for USp(2k) with an antisymmetric hypermultiplet and pure SU(N) gauge theories.

Guiding modes of semi-infinite nanowire and their dispersion character

International Nuclear Information System (INIS)

Sun, Yuming; Su, Yuehua; Dai, Zhenhong; Wang, Weitian

2014-01-01

Conventionally, the optical properties of finite semiconductor nanowires have been understood and explained in terms of an infinite nanowire. This work describes completely different photonic modes for a semi-finite nanowire based on a rigorous theoretical method, and the implications for the finite one. First, the special eigenvalue problem charactered by the end results in a distinctive mode spectrum for the semi-infinite dielectric nanowire. Meanwhile, the results show hybrid degenerate modes away from cutoff frequency, and transverse electric–transverse magnetic (TE–TM) degeneracy. Second, accompanying a different mode spectrum, a semi-finite nanowire also shows a distinctive dispersion relation compared to an infinite nanowire. Taking a semi-infinite, ZnO nanowire as an example, we find that the ℏω−k z space is not continuous in the interested photon energy window, implying that there is no uniform polariton dispersion relation for semi-infinite nanowire. Our method is shown correct through a field-reconstruction for a thin ZnO nanowire (55 nm in radius) and position determination of FP modes for a ZnO nanowire (200 nm in diameter). The results are of great significance to correctly understand the guiding and lasing mechanisms of semiconductor nanowires. (paper)

A non-linear elastic constitutive framework for replicating plastic deformation in solids.

Energy Technology Data Exchange (ETDEWEB)

Roberts, Scott Alan; Schunk, Peter Randall

2014-02-01

Ductile metals and other materials typically deform plastically under large applied loads; a behavior most often modeled using plastic deformation constitutive models. However, it is possible to capture some of the key behaviors of plastic deformation using only the framework for nonlinear elastic mechanics. In this paper, we develop a phenomenological, hysteretic, nonlinear elastic constitutive model that captures many of the features expected of a plastic deformation model. This model is based on calculating a secant modulus directly from a materials stress-strain curve. Scalar stress and strain values are obtained in three dimensions by using the von Mises invariants. Hysteresis is incorporated by tracking an additional history variable and assuming an elastic unloading response. This model is demonstrated in both single- and multi-element simulations under varying strain conditions.

Bright circularly polarized soft X-ray high harmonics for X-ray magnetic circular dichroism.

Science.gov (United States)

Fan, Tingting; Grychtol, Patrik; Knut, Ronny; Hernández-García, Carlos; Hickstein, Daniel D; Zusin, Dmitriy; Gentry, Christian; Dollar, Franklin J; Mancuso, Christopher A; Hogle, Craig W; Kfir, Ofer; Legut, Dominik; Carva, Karel; Ellis, Jennifer L; Dorney, Kevin M; Chen, Cong; Shpyrko, Oleg G; Fullerton, Eric E; Cohen, Oren; Oppeneer, Peter M; Milošević, Dejan B; Becker, Andreas; Jaroń-Becker, Agnieszka A; Popmintchev, Tenio; Murnane, Margaret M; Kapteyn, Henry C

2015-11-17

We demonstrate, to our knowledge, the first bright circularly polarized high-harmonic beams in the soft X-ray region of the electromagnetic spectrum, and use them to implement X-ray magnetic circular dichroism measurements in a tabletop-scale setup. Using counterrotating circularly polarized laser fields at 1.3 and 0.79 µm, we generate circularly polarized harmonics with photon energies exceeding 160 eV. The harmonic spectra emerge as a sequence of closely spaced pairs of left and right circularly polarized peaks, with energies determined by conservation of energy and spin angular momentum. We explain the single-atom and macroscopic physics by identifying the dominant electron quantum trajectories and optimal phase-matching conditions. The first advanced phase-matched propagation simulations for circularly polarized harmonics reveal the influence of the finite phase-matching temporal window on the spectrum, as well as the unique polarization-shaped attosecond pulse train. Finally, we use, to our knowledge, the first tabletop X-ray magnetic circular dichroism measurements at the N4,5 absorption edges of Gd to validate the high degree of circularity, brightness, and stability of this light source. These results demonstrate the feasibility of manipulating the polarization, spectrum, and temporal shape of high harmonics in the soft X-ray region by manipulating the driving laser waveform.

Approximate analytical method to evaluate diffraction crosstalk in free-space optical interconnects systems that use circular microlenses with finite uniform apertures

Science.gov (United States)

Al-Ababneh, Nedal

2014-07-01

We propose an accurate analytical model to calculate the optical crosstalk of a first-order free space optical interconnects system that uses microlenses with circular apertures. The proposed model is derived by evaluating the resulted finite integral in terms of an infinite series of Bessel functions. Compared to the model that uses complex Gaussian functions to expand the aperture function, it is shown that the proposed model is superior in estimating the crosstalk and provides more accurate results. Moreover, it is shown that the proposed model gives results close to that of the numerical model with superior computational efficiency.

Estimation Methods for Infinite-Dimensional Systems Applied to the Hemodynamic Response in the Brain

KAUST Repository

Belkhatir, Zehor

2018-05-01

Infinite-Dimensional Systems (IDSs) which have been made possible by recent advances in mathematical and computational tools can be used to model complex real phenomena. However, due to physical, economic, or stringent non-invasive constraints on real systems, the underlying characteristics for mathematical models in general (and IDSs in particular) are often missing or subject to uncertainty. Therefore, developing efficient estimation techniques to extract missing pieces of information from available measurements is essential. The human brain is an example of IDSs with severe constraints on information collection from controlled experiments and invasive sensors. Investigating the intriguing modeling potential of the brain is, in fact, the main motivation for this work. Here, we will characterize the hemodynamic behavior of the brain using functional magnetic resonance imaging data. In this regard, we propose efficient estimation methods for two classes of IDSs, namely Partial Differential Equations (PDEs) and Fractional Differential Equations (FDEs). This work is divided into two parts. The first part addresses the joint estimation problem of the state, parameters, and input for a coupled second-order hyperbolic PDE and an infinite-dimensional ordinary differential equation using sampled-in-space measurements. Two estimation techniques are proposed: a Kalman-based algorithm that relies on a reduced finite-dimensional model of the IDS, and an infinite-dimensional adaptive estimator whose convergence proof is based on the Lyapunov approach. We study and discuss the identifiability of the unknown variables for both cases. The second part contributes to the development of estimation methods for FDEs where major challenges arise in estimating fractional differentiation orders and non-smooth pointwise inputs. First, we propose a fractional high-order sliding mode observer to jointly estimate the pseudo-state and input of commensurate FDEs. Second, we propose a

The root infinitive stage in a null subject language: Romance in the Balkans

Directory of Open Access Journals (Sweden)

Larisa Avram

2007-01-01

Full Text Available The aim of the present paper is to determine which early non-finite verbal form is the Root Infinitive analogue in Romanian, an Inflection-licensed null subject language. In particular, we investigate whether the RI-analogue is the imperative, as predicted by Salustri and Hyams’s (2003 hypothesis, or whether it is a language specific underspecified form, overused during the early stages of acquisition, as predicted by Wexler et al. (2004.

Coupled spin, elastic and charge dynamics in magnetic nanostructures

NARCIS (Netherlands)

Kamra, A.

2015-01-01

In this Thesis, I address the interaction of magnetic degrees of freedom with charge current and elastic dynamics in hybrid systems composed of magnetic and non-magnetic materials. The objective, invariably, is to control and study spin dynamics using charge and elastic degrees of freedom. In

Semantic coherence in English accusative-with-bare-infinitive constructions

DEFF Research Database (Denmark)

Jensen, Kim Ebensgaard

2013-01-01

-with-bare-infinitive construction. The main methodological framework is that of covarying collexeme analysis, which, through statistical corpus analysis, allows for the analyst to address the semantics of a construction. Using this method on data from the BNC, the ultimate purpose of the paper is to address the underlying semantic...... relations of English accusatives-with-bare-infinitives through the relations of semantic coherence between the two VPs....

Numerical form-finding method for large mesh reflectors with elastic rim trusses

Science.gov (United States)

Yang, Dongwu; Zhang, Yiqun; Li, Peng; Du, Jingli

2018-06-01

Traditional methods for designing a mesh reflector usually treat the rim truss as rigid. Due to large aperture, light weight and high accuracy requirements on spaceborne reflectors, the rim truss deformation is indeed not negligible. In order to design a cable net with asymmetric boundaries for the front and rear nets, a cable-net form-finding method is firstly introduced. Then, the form-finding method is embedded into an iterative approach for designing a mesh reflector considering the elasticity of the supporting rim truss. By iterations on form-findings of the cable-net based on the updated boundary conditions due to the rim truss deformation, a mesh reflector with a fairly uniform tension distribution in its equilibrium state could be finally designed. Applications on offset mesh reflectors with both circular and elliptical rim trusses are illustrated. The numerical results show the effectiveness of the proposed approach and that a circular rim truss is more stable than an elliptical rim truss.

THE INTERACTION OF A COLD ATOMISED SPRAY WITH A CIRCULAR CYLINDER

Directory of Open Access Journals (Sweden)

A. AROUSSI

2010-09-01

Full Text Available The development of non-intrusive diagnostic techniques has significantly increased with the introduction of lasers. Laser based anemometry, such as Laser Doppler (LDA, Phase Doppler (PDA, and Particle Image Velocimetery (PIV can provide an accurate description of flows without interference. This study determines experimentally the fluid motion resulting from the interaction of a liquid spray with a circular cylinder. Two experimental settings were examined: the first is a discharging spray into free air and the second is a spray impinging on a circular cylinder placed 25 cylinder diameters downstream of the nozzle. These sprays were quantified using PIV. A non-intrusive droplet sizing technique was used to characterise the spray. This has shown that, within the spray, the average droplet diameter increases when the circular cylinder is introduced and so does the frequency of occurrence of these large droplets. In the wake behind the cylinder, the smaller droplets were quickly entrained and recirculated, while the larger droplets continued in the general direction of the spray cone.

Three dimensional vibration and bending analysis of carbon nanotubes embedded in elastic medium based on theory of elasticity

Directory of Open Access Journals (Sweden)

M. Shaban

Full Text Available This paper studies free vibration and bending behavior of singlewalled carbon nanotubes (SWCNTs embedded on elastic medium based on three-dimensional theory of elasticity. To accounting the size effect of carbon nanotubes, non-local theory is adopted to shell model. The nonlocal parameter is incorporated into all constitutive equations in three dimensions. The surrounding medium is modeled as two-parameter elastic foundation. By using Fourier series expansion in axial and circumferential direction, the set of coupled governing equations are reduced to the ordinary differential equations in thickness direction. Then, the state-space method as an efficient and accurate method is used to solve the resulting equations analytically. Comprehensive parametric studies are carried out to show the influences of the nonlocal parameter, radial and shear elastic stiffness, thickness-to-radius ratio and radiusto-length ratio.

Identification of Novel Long Non-coding and Circular RNAs in Human Papillomavirus-Mediated Cervical Cancer

Directory of Open Access Journals (Sweden)

Hongbo Wang

2017-09-01

Full Text Available Cervical cancer is the third most common cancer worldwide and the fourth leading cause of cancer-associated mortality in women. Accumulating evidence indicates that long non-coding RNAs (lncRNAs and circular RNAs (circRNAs may play key roles in the carcinogenesis of different cancers; however, little is known about the mechanisms of lncRNAs and circRNAs in the progression and metastasis of cervical cancer. In this study, we explored the expression profiles of lncRNAs, circRNAs, miRNAs, and mRNAs in HPV16 (human papillomavirus genotype 16 mediated cervical squamous cell carcinoma and matched adjacent non-tumor (ATN tissues from three patients with high-throughput RNA sequencing (RNA-seq. In total, we identified 19 lncRNAs, 99 circRNAs, 28 miRNAs, and 304 mRNAs that were commonly differentially expressed (DE in different patients. Among the non-coding RNAs, 3 lncRNAs and 44 circRNAs are novel to our knowledge. Functional enrichment analysis showed that DE lncRNAs, miRNAs, and mRNAs were enriched in pathways crucial to cancer as well as other gene ontology (GO terms. Furthermore, the co-expression network and function prediction suggested that all 19 DE lncRNAs could play different roles in the carcinogenesis and development of cervical cancer. The competing endogenous RNA (ceRNA network based on DE coding and non-coding RNAs showed that each miRNA targeted a number of lncRNAs and circRNAs. The link between part of the miRNAs in the network and cervical cancer has been validated in previous studies, and these miRNAs targeted the majority of the novel non-coding RNAs, thus suggesting that these novel non-coding RNAs may be involved in cervical cancer. Taken together, our study shows that DE non-coding RNAs could be further developed as diagnostic and therapeutic biomarkers of cervical cancer. The complex ceRNA network also lays the foundation for future research of the roles of coding and non-coding RNAs in cervical cancer.

Identification of Novel Long Non-coding and Circular RNAs in Human Papillomavirus-Mediated Cervical Cancer

Science.gov (United States)

Wang, Hongbo; Zhao, Yingchao; Chen, Mingyue; Cui, Jie

2017-01-01

Cervical cancer is the third most common cancer worldwide and the fourth leading cause of cancer-associated mortality in women. Accumulating evidence indicates that long non-coding RNAs (lncRNAs) and circular RNAs (circRNAs) may play key roles in the carcinogenesis of different cancers; however, little is known about the mechanisms of lncRNAs and circRNAs in the progression and metastasis of cervical cancer. In this study, we explored the expression profiles of lncRNAs, circRNAs, miRNAs, and mRNAs in HPV16 (human papillomavirus genotype 16) mediated cervical squamous cell carcinoma and matched adjacent non-tumor (ATN) tissues from three patients with high-throughput RNA sequencing (RNA-seq). In total, we identified 19 lncRNAs, 99 circRNAs, 28 miRNAs, and 304 mRNAs that were commonly differentially expressed (DE) in different patients. Among the non-coding RNAs, 3 lncRNAs and 44 circRNAs are novel to our knowledge. Functional enrichment analysis showed that DE lncRNAs, miRNAs, and mRNAs were enriched in pathways crucial to cancer as well as other gene ontology (GO) terms. Furthermore, the co-expression network and function prediction suggested that all 19 DE lncRNAs could play different roles in the carcinogenesis and development of cervical cancer. The competing endogenous RNA (ceRNA) network based on DE coding and non-coding RNAs showed that each miRNA targeted a number of lncRNAs and circRNAs. The link between part of the miRNAs in the network and cervical cancer has been validated in previous studies, and these miRNAs targeted the majority of the novel non-coding RNAs, thus suggesting that these novel non-coding RNAs may be involved in cervical cancer. Taken together, our study shows that DE non-coding RNAs could be further developed as diagnostic and therapeutic biomarkers of cervical cancer. The complex ceRNA network also lays the foundation for future research of the roles of coding and non-coding RNAs in cervical cancer. PMID:28970820

Infinite tension limit of the pure spinor superstring

Energy Technology Data Exchange (ETDEWEB)

Berkovits, Nathan [ICTP South American Institute for Fundamental Research,Instituto de Física Teórica, UNESP - Univ. Estadual Paulista,Rua Dr. Bento T. Ferraz 271, 01140-070, São Paulo, SP (Brazil)

2014-03-04

Mason and Skinner recently constructed a chiral infinite tension limit of the Ramond-Neveu-Schwarz superstring which was shown to compute the Cachazo-He-Yuan formulae for tree-level d=10 Yang-Mills amplitudes and the NS-NS sector of tree-level d=10 supergravity amplitudes. In this letter, their chiral infinite tension limit is generalized to the pure spinor superstring which computes a d=10 superspace version of the Cachazo-He-Yuan formulae for tree-level d=10 super-Yang-Mills and supergravity amplitudes.

Alteration of the superconducting properties of A15 compounds and elementary composite superconductors by non-hydrostatic elastic strain

International Nuclear Information System (INIS)

Welch, D.O.

1979-01-01

Elastic strains alter (usually, but not always, adversely) the critical temperatures, magnetic fields, and current densities of superconducting A15 compounds; non-hydrostatic strain states are particularly effective in this regard. This paper is a review of the experimental evidence, obtained by a variety of techniques, concerning the strain dependence of the critical properties of a number of A15 compounds and a discussion of theoretical models for describing such effects

Publication of administrative circular

CERN Multimedia

HR Department

2009-01-01

ADMINISTRATIVE CIRCULAR NO. 23 (REV. 2) – SPECIAL WORKING HOURS Administrative Circular No. 23 (Rev. 2) entitled "Special working hours", approved following discussion in the Standing Concertation Committee on 9 December 2008, will be available on the intranet site of the Human Resources Department as from 19 December 2008: http://cern.ch/hr-docs/admincirc/admincirc.asp It cancels and replaces Administrative Circular No. 23 (Rev. 1) entitled "Stand-by duty" of April 1988. A "Frequently Asked Questions" information document on special working hours will also be available on this site. Paper copies of this circular will shortly be available in Departmental Secretariats. Human Resources Department Tel. 78003

PUBLICATION OF ADMINISTRATIVE CIRCULAR

CERN Multimedia

HR Department

2008-01-01

ADMINISTRATIVE CIRCULAR NO. 23 (REV. 2) – SPECIAL WORKING HOURS Administrative Circular No. 23 (Rev. 2) entitled "Special working hours", approved following discussion in the Standing Concertation Committee meeting of 9 December 2008, will be available on the intranet site of the Human Resources Department as from 19 December 2008: http://cern.ch/hr-docs/admincirc/admincirc.asp It cancels and replaces Administrative Circular No. 23 (Rev. 1) entitled "Stand-by duty" of April 1988. A "Frequently Asked Questions" information document on special working hours will also be available on this site. Paper copies of this circular will shortly be available in departmental secretariats. Human Resources Department Tel. 78003

Rotation of an immersed cylinder sliding near a thin elastic coating

Science.gov (United States)

Rallabandi, Bhargav; Saintyves, Baudouin; Jules, Theo; Salez, Thomas; Schönecker, Clarissa; Mahadevan, L.; Stone, Howard A.

2017-07-01

It is known that an object translating parallel to a soft wall in a viscous fluid produces hydrodynamic stresses that deform the wall, which in turn results in a lift force on the object. Recent experiments with cylinders sliding under gravity near a soft incline, which confirmed theoretical arguments for the lift force, also reported an unexplained steady-state rotation of the cylinders [B. Saintyves et al., Proc. Natl. Acad. Sci. USA 113, 5847 (2016), 10.1073/pnas.1525462113]. Motivated by these observations, we show, in the lubrication limit, that an infinite cylinder that translates in a viscous fluid parallel to a soft wall at constant speed and separation distance must also rotate in order to remain free of torque. Using the Lorentz reciprocal theorem, we show analytically that for small deformations of the elastic layer, the angular velocity of the cylinder scales with the cube of the sliding speed. These predictions are confirmed numerically. We then apply the theory to the gravity-driven motion of a cylinder near a soft incline and find qualitative agreement with the experimental observations, namely, that a softer elastic layer results in a greater angular speed of the cylinder.

Probabilistic Infinite Secret Sharing

OpenAIRE

Csirmaz, László

2013-01-01

The study of probabilistic secret sharing schemes using arbitrary probability spaces and possibly infinite number of participants lets us investigate abstract properties of such schemes. It highlights important properties, explains why certain definitions work better than others, connects this topic to other branches of mathematics, and might yield new design paradigms. A probabilistic secret sharing scheme is a joint probability distribution of the shares and the secret together with a colle...

Aerodynamics and Hovering Control of LTA Vehicles

Science.gov (United States)

1977-05-01

not at all the usual terminology for Magnus Force which is usually thought of as arising from viscous effects when cylinder or sphere is rotating and...Number for Circular Cylinders 9 Ratio of the Drag Coefficient of a Circular Cylinder 29 of Finite Length to That of a Cylincer of Infinite Length as...Application of Non-Linear Drag 82 30 Directional Stability Derivative 83 31 Center of Lateral Pressure Location 84 32 Dihedral Effect Derivative 85 v Figures

Non-linear waves in heterogeneous elastic rods via homogenization

KAUST Repository

Quezada de Luna, Manuel

2012-03-01

We consider the propagation of a planar loop on a heterogeneous elastic rod with a periodic microstructure consisting of two alternating homogeneous regions with different material properties. The analysis is carried out using a second-order homogenization theory based on a multiple scale asymptotic expansion. © 2011 Elsevier Ltd. All rights reserved.

Self-bending elastic waves and obstacle circumventing in wireless power transfer

Science.gov (United States)

Tol, S.; Xia, Y.; Ruzzene, M.; Erturk, A.

2017-04-01

We demonstrate self-bending of elastic waves along convex trajectories by means of geometric and phased arrays. Potential applications include ultrasonic imaging and manipulation, wave focusing, and wireless power transfer around obstacles. The basic concept is illustrated through a geometric array, which is designed to implement a phase delay profile among the array elements that leads to self-bending along a specified circular trajectory. Experimental validation is conducted for the lowest asymmetric Lamb wave mode in a thin plate over a range of frequencies to investigate the bandwidth of the approach. Experiments also illustrate the functionality of the array as a transmitter to deliver elastic wave energy to a receiver/harvester located behind a large obstacle for electrical power extraction. It is shown that the trajectory is not distorted by the presence of the obstacle and circumventing is achieved. A linear phased array counterpart of the geometric array is then constructed to illustrate the concept by imposing proper time delays to the array elements, which allows the generation of different trajectories using the same line source. This capability is demonstrated by tailoring the path diameter in the phased array setting, which offers the flexibility and versatility to induce a variety of convex trajectories for self-bending elastic waves.

KLN theorem and infinite statistics

International Nuclear Information System (INIS)

Grandou, T.

1992-01-01

The possible extension of the Kinoshita-Lee-Nauenberg (KLN) theorem to the case of infinite statistics is examined. It is shown that it appears as a stable structure in a quantum field theory context. The extension is provided by working out the Fock space realization of a 'quantum algebra'. (author) 2 refs

Nonlinear modulation of torsional waves in elastic rod. [Instability

Energy Technology Data Exchange (ETDEWEB)

Hirao, M; Sugimoto, N [Osaka Univ., Toyonaka (Japan). Faculty of Engineering Science

1977-06-01

Nonlinear Schroedinger equation, which describes the nonlinear modulation of dispersive torsional waves in an elastic rod of circular cross-section, is derived by the derivative expansion method. It is found, for the lowest dispersive mode, that the modulational instability occurs except in the range of the carrier wavenumber, 2.799

Orientations of infinite graphs with prescribed edge-connectivity

DEFF Research Database (Denmark)

Thomassen, Carsten

2016-01-01

We prove a decomposition result for locally finite graphs which can be used to extend results on edge-connectivity from finite to infinite graphs. It implies that every 4k-edge-connected graph G contains an immersion of some finite 2k-edge-connected Eulerian graph containing any prescribed vertex...... set (while planar graphs show that G need not containa subdivision of a simple finite graph of large edge-connectivity). Also, every 8k-edge connected infinite graph has a k-arc-connected orientation, as conjectured in 1989....

Infinite Spin Fields in d = 3 and Beyond

Directory of Open Access Journals (Sweden)

Yurii M. Zinoviev

2017-08-01

Full Text Available In this paper, we consider the frame-like formulation for the so-called infinite (continuous spin representations of the Poincare algebra. In the three-dimensional case, we give explicit Lagrangian formulation for bosonic and fermionic infinite spin fields (including the complete sets of the gauge-invariant objects and all the necessary extra fields. Moreover, we find the supertransformations for the supermultiplet containing one bosonic and one fermionic field, leaving the sum of their Lagrangians invariant. Properties of such fields and supermultiplets in four and higher dimensions are also briefly discussed.

The elasticity of drugs demand in Colombia’s pharmaceutical market

Directory of Open Access Journals (Sweden)

Johanna Vásquez Velásquez

2013-06-01

Full Text Available Based on a dynamic specification of the AIDS model arisen from cointegration techniques, this research estimated the elasticity of the intra-molecular, brand and generic demand for three tracer conditions: essential hypertension, diabetes and hyperlipidemia both in the non-profit and private Colombian market. The estimate of the intra-molecular demand elasticity allows us to conclude that both brand-name and generic drugs are inelastic to price changes, they are luxury goods according to expenditure elasticity and intra-molecular replacement seems to exist due to the elasticity of substitution.

Stress field of a near-surface basal screw dislocation in elastically anisotropic hexagonal crystals

Directory of Open Access Journals (Sweden)

Valeri S. Harutyunyan

2017-11-01

Full Text Available In this study, we derive and analyze the analytical expressions for stress components of the dislocation elastic field induced by a near-surface basal screw dislocation in a semi-infinite elastically anisotropic material with hexagonal crystal lattice. The variation of above stress components depending on “free surface–dislocation” distance (i.e., free surface effect is studied by means of plotting the stress distribution maps for elastically anisotropic crystals of GaN and TiB2 that exhibit different degrees of elastic anisotropy. The dependence both of the image force on a screw dislocation and the force of interaction between two neighboring basal screw dislocations on the “free surface–dislocation” distance is analyzed as well. The influence of elastic anisotropy on the latter force is numerically analyzed for GaN and TiB2 and also for crystals of such highly elastically-anisotropic materials as Ti, Zn, Cd, and graphite. The comparatively stronger effect of the elastic anisotropy on dislocation-induced stress distribution quantified for TiB2 is attributed to the higher degree of elastic anisotropy of this compound in comparison to that of the GaN. For GaN and TiB2, the dislocation stress distribution maps are highly influenced by the free surface effect at “free surface–dislocation” distances roughly smaller than ≈15 and ≈50 nm, respectively. It is found that, for above indicated materials, the relative decrease of the force of interaction between near-surface screw dislocations due to free surface effect is in the order Ti > GaN > TiB2 > Zn > Cd > Graphite that results from increase of the specific shear anisotropy parameter in the reverse order Ti < GaN < TiB2 < Zn < Cd < Graphite. The results obtained in this study are also applicable to the case when a screw dislocation is situated in the “thin film–substrate” system at a (0001 basal interface between the film and substrate provided that the elastic constants

Recent developments in chiral gauge theories: approach of infinitely many fermi fields

International Nuclear Information System (INIS)

Narayanan, R.

1994-01-01

I present the recent developments in a specific sub-field of chiral gauge theories on the lattice. This subfield pertains to the use of infinitely many fermi fields to describe a single chiral field. In this approach, both anomalous and anomaly free theories can be discussed in equal footing. It produces the correct anomaly in the continuum limit. It has the potential to describe fermion number violating processes in the presence of a gauge field background with non-trivial topological charge on a finite lattice. (orig.)

Infinite-component conformal fields. Spectral representation of the two-point function

International Nuclear Information System (INIS)

Zaikov, R.P.; Tcholakov, V.

1975-01-01

The infinite-component conformal fields (with respect to the stability subgroup) are considered. The spectral representation of the conformally invariant two-point function is obtained. This function is nonvanishing as/lso for one ''fundamental'' and one infinite-component field

Zirconium elasticity modules

International Nuclear Information System (INIS)

Vavra, G.

1978-01-01

Considered are the limit and the intermediate values of the Young modulus E, modulus of shear G and of linear modulus of compression K obtainable at various temperatures (4.2 to 1133 K) for single crystals of α-zirconium. Determined and presented are the corrected isotropic elasticity characteristics of E, G, K over the above range of temperatures of textured and non-textured α-Zr

Numerical simulation of shear and the Poynting effects by the finite element method: An application of the generalised empirical inequalities in non-linear elasticity

KAUST Repository

Angela Mihai, L.; Goriely, Alain

2013-01-01

Finite element simulations of different shear deformations in non-linear elasticity are presented. We pay particular attention to the Poynting effects in hyperelastic materials, complementing recent theoretical findings by showing these effects

Representations of the infinite symmetric group

CERN Document Server

Borodin, Alexei

2016-01-01

Representation theory of big groups is an important and quickly developing part of modern mathematics, giving rise to a variety of important applications in probability and mathematical physics. This book provides the first concise and self-contained introduction to the theory on the simplest yet very nontrivial example of the infinite symmetric group, focusing on its deep connections to probability, mathematical physics, and algebraic combinatorics. Following a discussion of the classical Thoma's theorem which describes the characters of the infinite symmetric group, the authors describe explicit constructions of an important class of representations, including both the irreducible and generalized ones. Complete with detailed proofs, as well as numerous examples and exercises which help to summarize recent developments in the field, this book will enable graduates to enhance their understanding of the topic, while also aiding lecturers and researchers in related areas.

The Bearing Capacity of Circular Footings in Sand

DEFF Research Database (Denmark)

Krabbenhøft, Sven; Clausen, Johan; Damkilde, Lars

2012-01-01

dependent on the stress level and on the basis of the test results, a non linear Mohr failure criterion has been proposed. This yield criterion has been implemented in a finite element program and an analysis of the bearing capacity of a circular shaped model foundation, diameter 100mm, has been conducted...

On the statistical and transport properties of a non-dissipative Fermi-Ulam model

Science.gov (United States)

Livorati, André L. P.; Dettmann, Carl P.; Caldas, Iberê L.; Leonel, Edson D.

2015-10-01

The transport and diffusion properties for the velocity of a Fermi-Ulam model were characterized using the decay rate of the survival probability. The system consists of an ensemble of non-interacting particles confined to move along and experience elastic collisions with two infinitely heavy walls. One is fixed, working as a returning mechanism of the colliding particles, while the other one moves periodically in time. The diffusion equation is solved, and the diffusion coefficient is numerically estimated by means of the averaged square velocity. Our results show remarkably good agreement of the theory and simulation for the chaotic sea below the first elliptic island in the phase space. From the decay rates of the survival probability, we obtained transport properties that can be extended to other nonlinear mappings, as well to billiard problems.

Deuteron D-wave and the non-eikonal effects in tensor asymmetries in elastic proton-deuteron scattering

International Nuclear Information System (INIS)

Alberi, G.; Bleszynski, M.; California Univ., Los Angeles; Santos, S.; Jaroszewicz, T.

1980-01-01

It is shown that the tensor asymmetries in the elastic proton-deuteron scattering at medium energies are very sensitive to the non-eikonal corrections to the Glauber model. This sensitivity originates from the fact that, in double scattering, the non-eikonal corrections affect in a different way the contributions coming from the S- and D-wave parts of the deuteron wave function. This leads to considerable change of the tensor asymmetries not only in the region of the interference between single and double scatterings, but also in the region of dominance of the double scattering. It is suggested that these effects should be taken into account in any careful analysis of the proton-deuteron polarization data, which has as a goal the extraction of the NN amplitudes. (author)

Self-Assembly of Infinite Structures

Directory of Open Access Journals (Sweden)

Scott M. Summers

2009-06-01

Full Text Available We review some recent results related to the self-assembly of infinite structures in the Tile Assembly Model. These results include impossibility results, as well as novel tile assembly systems in which shapes and patterns that represent various notions of computation self-assemble. Several open questions are also presented and motivated.

Gini estimation under infinite variance

NARCIS (Netherlands)

A. Fontanari (Andrea); N.N. Taleb (Nassim Nicholas); P. Cirillo (Pasquale)

2018-01-01

textabstractWe study the problems related to the estimation of the Gini index in presence of a fat-tailed data generating process, i.e. one in the stable distribution class with finite mean but infinite variance (i.e. with tail index α∈(1,2)). We show that, in such a case, the Gini coefficient

Squashed entanglement in infinite dimensions

International Nuclear Information System (INIS)

Shirokov, M. E.

2016-01-01

We analyse two possible definitions of the squashed entanglement in an infinite-dimensional bipartite system: direct translation of the finite-dimensional definition and its universal extension. It is shown that the both definitions produce the same lower semicontinuous entanglement measure possessing all basis properties of the squashed entanglement on the set of states having at least one finite marginal entropy. It is also shown that the second definition gives an adequate lower semicontinuous extension of this measure to all states of the infinite-dimensional bipartite system. A general condition relating continuity of the squashed entanglement to continuity of the quantum mutual information is proved and its corollaries are considered. Continuity bound for the squashed entanglement under the energy constraint on one subsystem is obtained by using the tight continuity bound for quantum conditional mutual information (proved in the Appendix by using Winter’s technique). It is shown that the same continuity bound is valid for the entanglement of formation. As a result the asymptotic continuity of the both entanglement measures under the energy constraint on one subsystem is proved.

analysis of pressure variation of fluid in an infinite acting reservoir

African Journals Online (AJOL)

user

2017-01-01

Jan 1, 2017 ... radial diffusivity equation for a reservoir acting as if it was infinite in size and ... differential equation there is an infinite number of a possible solution ..... [3] Van Everdingen, A. F. and Hurst, W. The Application of the. Laplace ...

Fatigue crack detection and identification by the elastic wave propagation method

Science.gov (United States)

Stawiarski, Adam; Barski, Marek; Pająk, Piotr

2017-05-01

In this paper the elastic wave propagation phenomenon was used to detect the initiation of the fatigue damage in isotropic plate with a circular hole. The safety and reliability of structures mostly depend on the effectiveness of the monitoring methods. The Structural Health Monitoring (SHM) system based on the active pitch-catch measurement technique was proposed. The piezoelectric (PZT) elements was used as an actuators and sensors in the multipoint measuring system. The comparison of the intact and defected structures has been used by damage detection algorithm. One part of the SHM system has been responsible for detection of the fatigue crack initiation. The second part observed the evolution of the damage growth and assess the size of the defect. The numerical results of the wave propagation phenomenon has been used to present the effectiveness and accuracy of the proposed method. The preliminary experimental analysis has been carried out during the tension test of the aluminum plate with a circular hole to determine the efficiency of the measurement technique.

Fully coupled heat conduction and deformation analyses of visco-elastic solids

KAUST Repository

Khan, Kamran

2012-04-21

Visco-elastic materials are known for their capability of dissipating energy. This energy is converted into heat and thus changes the temperature of the materials. In addition to the dissipation effect, an external thermal stimulus can also alter the temperature in a viscoelastic body. The rate of stress relaxation (or the rate of creep) and the mechanical and physical properties of visco-elastic materials, such as polymers, vary with temperature. This study aims at understanding the effect of coupling between the thermal and mechanical response that is attributed to the dissipation of energy, heat conduction, and temperature-dependent material parameters on the overall response of visco-elastic solids. The non-linearly viscoelastic constitutive model proposed by Schapery (Further development of a thermodynamic constitutive theory: stress formulation, 1969,Mech. Time-Depend. Mater. 1:209-240, 1997) is used and modified to incorporate temperature- and stress-dependent material properties. This study also formulates a non-linear energy equation along with a dissipation function based on the Gibbs potential of Schapery (Mech. Time-Depend. Mater. 1:209-240, 1997). A numerical algorithm is formulated for analyzing a fully coupled thermo-visco-elastic response and implemented it in a general finite-element (FE) code. The non-linear stress- and temperature-dependent material parameters are found to have significant effects on the coupled thermo-visco-elastic response of polymers considered in this study. In order to obtain a realistic temperature field within the polymer visco-elastic bodies undergoing a non-uniform heat generation, the role of heat conduction cannot be ignored. © Springer Science+Business Media, B. V. 2012.

Elastic Gauge Fields in Weyl Semimetals

Science.gov (United States)

Cortijo, Alberto; Ferreiros, Yago; Landsteiner, Karl; Hernandez Vozmediano, Maria Angeles

We show that, as it happens in graphene, elastic deformations couple to the electronic degrees of freedom as pseudo gauge fields in Weyl semimetals. We derive the form of the elastic gauge fields in a tight-binding model hosting Weyl nodes and see that this vector electron-phonon coupling is chiral, providing an example of axial gauge fields in three dimensions. As an example of the new response functions that arise associated to these elastic gauge fields, we derive a non-zero phonon Hall viscosity for the neutral system at zero temperature. The axial nature of the fields provides a test of the chiral anomaly in high energy with three axial vector couplings. European Union structural funds and the Comunidad de Madrid MAD2D-CM Program (S2013/MIT-3007).

Flag varieties, toric varieties, and suspensions: Three instances of infinite transitivity

International Nuclear Information System (INIS)

Arzhantsev, Ivan V; Zaidenberg, M G; Kuyumzhiyan, Karine G

2012-01-01

We say that a group G acts infinitely transitively on a set X if for every m element of N the induced diagonal action of G is transitive on the cartesian mth power X m backslash Δ with the diagonals removed. We describe three classes of affine algebraic varieties such that their automorphism groups act infinitely transitively on their smooth loci. The first class consists of normal affine cones over flag varieties, the second of nondegenerate affine toric varieties, and the third of iterated suspensions over affine varieties with infinitely transitive automorphism groups. Bibliography: 42 titles.

Failure assessment diagrams for circular hollow section X- and K-joints

International Nuclear Information System (INIS)

Qian, Xudong

2013-01-01

This paper reports the failure assessment curves for semi-elliptical surface cracks located at hot-spot positions in the circular hollow section X- and K-joints. The failure assessment curves derive from the square root of the ratio between the linear–elastic and the elastic–plastic energy release rates, computed from the domain-integral approach. This study examines both the material and geometric dependence of the failure assessment curves. The area reduction factor, used in defining the strength of the cracked joints, imposes a significant effect on the computed failure assessment curve. The failure assessment curves indicate negligible variations with respect to the crack-front locations and the material yield strength. The crack depth ratio exerts a stronger effect on the computed failure assessment curve than does the crack aspect ratio. This study proposes a parametric expression for the failure assessment curves based on the geometric parameters for surface cracks in circular hollow section X- and K-joints. -- Highlights: ► This study proposes geometric dependent expressions of FADs for tubular joints. ► We examine the geometric and material dependence of the FADs for X- and K-joints. ► The proposed FAD is independent of yield strength and is a lower-bound for typical hardening

Imaging linear and circular polarization features in leaves with complete Mueller matrix polarimetry.

Science.gov (United States)

Patty, C H Lucas; Luo, David A; Snik, Frans; Ariese, Freek; Buma, Wybren Jan; Ten Kate, Inge Loes; van Spanning, Rob J M; Sparks, William B; Germer, Thomas A; Garab, Győző; Kudenov, Michael W

2018-06-01

Spectropolarimetry of intact plant leaves allows to probe the molecular architecture of vegetation photosynthesis in a non-invasive and non-destructive way and, as such, can offer a wealth of physiological information. In addition to the molecular signals due to the photosynthetic machinery, the cell structure and its arrangement within a leaf can create and modify polarization signals. Using Mueller matrix polarimetry with rotating retarder modulation, we have visualized spatial variations in polarization in transmission around the chlorophyll a absorbance band from 650 nm to 710 nm. We show linear and circular polarization measurements of maple leaves and cultivated maize leaves and discuss the corresponding Mueller matrices and the Mueller matrix decompositions, which show distinct features in diattenuation, polarizance, retardance and depolarization. Importantly, while normal leaf tissue shows a typical split signal with both a negative and a positive peak in the induced fractional circular polarization and circular dichroism, the signals close to the veins only display a negative band. The results are similar to the negative band as reported earlier for single macrodomains. We discuss the possible role of the chloroplast orientation around the veins as a cause of this phenomenon. Systematic artefacts are ruled out as three independent measurements by different instruments gave similar results. These results provide better insight into circular polarization measurements on whole leaves and options for vegetation remote sensing using circular polarization. Copyright © 2018 The Author(s). Published by Elsevier B.V. All rights reserved.

Energy Dynamics of an Infinitely Large Offshore Wind Farm

DEFF Research Database (Denmark)

Frandsen, Sten Tronæs; Barthelmie, R.J.; Pryor, S.C.

, particularly in the near-term, can be expected in the higher resource, moderate water depths of the North Sea rather than the Mediterranean. There should therefore be significant interest in understanding the energy dynamics of the infinitely large wind farm – how wakes behave and whether the extraction...... of energy by wind turbines over a large area has a significant and lasting impact on the atmospheric boundary layer. Here we focus on developing understanding of the infinite wind farm through a combination of theoretical considerations, data analysis and modeling. Initial evaluation of power losses due...... is of about the same magnitude as for the infinitely large wind farm. We will examine whether this can be proved theoretically or is indicated by data currently available. We will also evaluate whether energy extraction at the likely scale of development in European Seas can be expected to modulate...

Complexity Analysis of Precedence Terminating Infinite Graph Rewrite Systems

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