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Small Deformation (small + deformation)

Distribution by Scientific Domains
Mathematics and Statistics25%

Selected Abstracts

Diffusion through time-dependent media

GEOPHYSICAL JOURNAL INTERNATIONAL, Issue 2 2000
M. Holschneider
Summary In this theoretical paper we show how to solve a time-dependent diffusion equation by means of a perturbation series. This technique is applied to the case of diffusion of a liquid through a time-dependent porous matrix. We compute to first order the phase and amplitude relations between the small deformation of the transporting matrix and the corresponding variation of the saturation at the surface. In particular we show that, for a large frequency range, there is a constant phase shift of ,/2 between the matrix and the surface saturation variations. Since the conductivity is to first approximation proportional to the saturation at the surface, this might explain the observed phase relations observed in an experiment in a cave near Abaratsubo (Japan). [source]

A relative index on the space of 3-dimensional embeddable CR-structures of finite type

MATHEMATISCHE NACHRICHTEN, Issue 4 2005
Peter Greiner
Abstract For a small deformation , of a 3-dimensional pseudoconvex embeddable CR-structure of finite type, we prove that , defines an embeddable CR-structure if and only if the Szegö projection from ker to ker is a Fredholm operator. This defines a relative index which is in this case equal to the negative of number of small eigenvalues of the operator . We also prove a cocycle formula for the relative index. (© 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]

Microstructure and magnetic properties of backward extruded NdFeB ring magnets by the CAPA process

PHYSICA STATUS SOLIDI (A) APPLICATIONS AND MATERIALS SCIENCE, Issue 8 2004
Hyoung-Tae Kim
Abstract The inhomogeneity in microstructure and magnetic properties of a ring magnet prepared by backward extrusion with a current-applied pressure-assisted process has been investigated. The initial part (top part) of a ring magnet prepared by back extrusion shows a high coercivity which is comparable to the raw powder. It exhibits isotropic characteristics along the three orthogonal directions probably due to small deformation. The last part (bottom part) of the ring magnet has a a low coercivity with large grains because high current flows through the pressurized punches during the whole deformation process as to increase the temperature and grain growth. The middle part is under an appropriate deformation with short time exposure at high temperature, therefore it maintains a relatively high remanent polarization with high coercivity. (© 2004 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]

Mass Transport Through PDMS/Clay Nanocomposite Membranes

THE CANADIAN JOURNAL OF CHEMICAL ENGINEERING, Issue 1 2007
Quan Liu
Abstract Poly(dimethylsiloxane)/clay nanocomposite membranes have been synthesized and mass transport properties through those nanocomposite membranes have been investigated. The effect of mechanical deformation on the transport properties of the PDMS (nanocomposite) membranes has also been studied. With the introduction of clay particles into the polymer matrix, mass transport is reduced, likely due to the longer diffusion path, which slows the diffusion process. The effect of membrane extension on diffusion is more complicated. Under small deformation, the permeation flux decreases, but under high deformation, it shows an enhanced diffusion. As the clay particle concentration increased, the effect of external deformation is reduced, and an enhanced diffusion is observed. On a synthétisé des membranes en nano-composites de polydiméthysiloxane et d'argile dans le but d'étudier leurs propriétés de transfert de matière. L'effet de la déformation mécanique sur les propriétés de transfert de ces membranes a également été étudié. Avec l'introduction des particules d'argile dans la matrice des polymères, le transfert de matière est réduit, probablement en raison du chemin de diffusion qui est plus long, ce qui ralentit le processus de diffusion. L'effet de l'extension des membranes sur la diffusion est plus compliqué. Sous faible déformation, le flux de perméation diminue, mais sous forte déformation, la diffusion est améliorée. Lorsque la concentration de particules d'argile augmente, l'effet de la déformation externe est réduit, et une meilleure diffusion est observée. [source]

Static self-gravitating elastic bodies in Einstein gravity

COMMUNICATIONS ON PURE & APPLIED MATHEMATICS, Issue 7 2008
Lars Andersson
We prove that given a stress-free elastic body there exists, for sufficiently small values of the gravitational constant, a unique static solution of the Einstein equations coupled to the equations of relativistic elasticity. The solution constructed is a small deformation of the relaxed configuration. This result yields the first proof of existence of static solutions of the Einstein equations without symmetries. © 2007 Wiley Periodicals, Inc. [source]

A critical plane fatigue model with coupled meso-plasticity and damage

FATIGUE & FRACTURE OF ENGINEERING MATERIALS AND STRUCTURES, Issue 1 2008
N. HUYEN
ABSTRACT The work proposed in this paper is a possible way of modelling some local observations at the surface of mild steel specimens submitted to uniaxial and multiaxial loads. It is clearly seen that local plasticity, controlled by local microstructural heterogeneities, plays a fundamental role in microcrack nucleation and damage orientation is closely related to the applied loading mode. The framework of irreversible thermodynamics with internal variables for time-independent, isothermal and small deformations has been used to build a critical plane damage model by assuming the existence of a link between mesoplasticity and mesodamage. Non-associated plasticity and damage rules allow the evolution of some plastic slip before any damage nucleation, as seen during the observations. A key feature of this proposal is the capacity to reflect nonlinear damage accumulation under variable amplitude loading. [source]

Lateral load distributions on grouped piles from dynamic pile-to-pile interaction factors

INTERNATIONAL JOURNAL FOR NUMERICAL AND ANALYTICAL METHODS IN GEOMECHANICS, Issue 2 2009
Der-Wen Chang
Abstract The load distributions of the grouped piles under lateral loads acting from one side of the pile cap could be approximately modeled using the elasticity equations with the assumptions that the underground structure is rigid enough to sustain the loads, and only small deformations of the soils are yielded. Variations of the soil,pile interactions along the depths are therefore negligible for simplicity. This paper presents the analytical modeling using the dynamic pile-to-pile interaction factors for 2,×,2 and 2,×,3 grouped piles. The results were found comparative with the experimental and numerical results of other studies. Similar to others' findings, it was shown that the leading pile could carry more static loads than the trailing pile does. For the piles in the perpendicular direction with the static load, the loads would distribute symmetrically with the centerline whereas the middle pile always sustains the smallest load. For steady-state loads with operating frequencies up to 30 Hz, the pile load distributions would vary significantly with the frequencies. It is interesting to know that designing the pile foundation needs to be cautioned for steady-state vibrations as they are a problem of machine foundation. However, for transient loads or any harmonic loads acting upon relatively higher frequencies, the pile loads could be regarded as uniformly distributed. It is hoped that the numerical results of this paper will be helpful in the design practice of pile foundation. Copyright © 2008 John Wiley & Sons, Ltd. [source]

Small unilateral jaw gap variations: equilibrium changes, co-contractions and joint forces

JOURNAL OF ORAL REHABILITATION, Issue 10 2009
H. J. SCHINDLER
Summary, After complex prosthetic reconstructions, small differences in vertical distances between the left and right side of the jaw may occur during jaw closing, nevertheless providing bilateral tooth contacts in intercuspation by small deformations of the mandible. Their effects on the co-contraction of the masticatory muscles, the temporomandibular joint reaction forces, and the point of application of the resultant bite force vector in the maxillary occlusion plane , the so-called reduction point , have not been investigated, thus far simultaneously in one sample. The main goal of this study was to investigate variations of these measures in an experimental intercuspation simulated by one anterior and two posterior force transmission points. [source]