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Bending of stochastic Kirchhoff plates on Winkler foundations via the Galerkin method and the Askey-Wiener scheme

SILVA JR., Claudio R. Avila da; BECK, Andre Teofilo
Fonte: ELSEVIER SCI LTD Publicador: ELSEVIER SCI LTD
Tipo: Artigo de Revista Científica
ENG
Relevância na Pesquisa
46.42%
In this paper, the method of Galerkin and the Askey-Wiener scheme are used to obtain approximate solutions to the stochastic displacement response of Kirchhoff plates with uncertain parameters. Theoretical and numerical results are presented. The Lax-Milgram lemma is used to express the conditions for existence and uniqueness of the solution. Uncertainties in plate and foundation stiffness are modeled by respecting these conditions, hence using Legendre polynomials indexed in uniform random variables. The space of approximate solutions is built using results of density between the space of continuous functions and Sobolev spaces. Approximate Galerkin solutions are compared with results of Monte Carlo simulation, in terms of first and second order moments and in terms of histograms of the displacement response. Numerical results for two example problems show very fast convergence to the exact solution, at excellent accuracies. The Askey-Wiener Galerkin scheme developed herein is able to reproduce the histogram of the displacement response. The scheme is shown to be a theoretically sound and efficient method for the solution of stochastic problems in engineering. (C) 2009 Elsevier Ltd. All rights reserved.; Sao Paulo State Foundation for Research - FAPESP[2008/10366-4]; National Council for Research and Development - CNPq[305120/2006-9]

Galerkin Solution of Stochastic Beam Bending on Winkler Foundations

SILVA, C. R. A.; HEUSI, H. P. Azikri de; MANTOVANI, G. E.; BECK, A. T.
Fonte: TECH SCIENCE PRESS Publicador: TECH SCIENCE PRESS
Tipo: Artigo de Revista Científica
ENG
Relevância na Pesquisa
56.56%
In this paper, the Askey-Wiener scheme and the Galerkin method are used to obtain approximate solutions to stochastic beam bending on Winkler foundation. The study addresses Euler-Bernoulli beams with uncertainty in the bending stiffness modulus and in the stiffness of the foundation. Uncertainties are represented by parameterized stochastic processes. The random behavior of beam response is modeled using the Askey-Wiener scheme. One contribution of the paper is a sketch of proof of existence and uniqueness of the solution to problems involving fourth order operators applied to random fields. From the approximate Galerkin solution, expected value and variance of beam displacement responses are derived, and compared with corresponding estimates obtained via Monte Carlo simulation. Results show very fast convergence and excellent accuracies in comparison to Monte Carlo simulation. The Askey-Wiener Galerkin scheme presented herein is shown to be a theoretically solid and numerically efficient method for the solution of stochastic problems in engineering.; Sao Paulo State Foundation for Research - FAPESP[2008/10366-4]; National Council for Research and Development - CNPq[305120/2006-9]

Analysis of plates on elastic foundation by the finite element method

Barros, Joaquim A. O.; Martins, Júlio Barreiros
Fonte: Universidade do Minho Publicador: Universidade do Minho
Tipo: Conferência ou Objeto de Conferência
Publicado em /08/1990 ENG
Relevância na Pesquisa
26.15%
The Mindlin`s theory for the bending of plates is formulated by the finite elements method in order to the analysis of plate structures resting on elastic media. The foundation soil is represented by springs with linear elastic behaviour (Winkler`s theory). A programme has been developped for small computers. It consists of three moduli: preprocessing which includes data preparation with graphic treatment (network generation and renumbering, etc.); displacements and support reactions calculation for each loading system; postprocessing, including options with numerical files creation and graphical treatment of results. The stiffness of the foundation soil can vary from point to point, the plate can have variable thickness and may be actuated by a large variety of types of loads.

Ground Vibrations Induced by High-Speed Trains in Regions with Sudden Foundation Stiffness Change

Dimitrovová, Zuzana; Varandas, José N.; Silva, Manuel A.G.
Fonte: Civil-Comp Press Publicador: Civil-Comp Press
Tipo: Conferência ou Objeto de Conferência
Publicado em /07/2007 ENG
Relevância na Pesquisa
36.2%
In this paper analytical transient solutions of dynamic response of one-dimensional systems with sudden change of foundation stiffness are derived. In more details, cantilever dynamic response, expressed in terms of vertical displacement, is extended to account for elastic foundation and then two cantilever solutions, corresponding to beams clamped on left and right hand side, with different value of Winkler constant are connected together by continuity conditions. The internal forces, as the unknowns, can be introduced by the same values in both clamped beam solutions and solved. Assumption about time variation of internal forces at the section of discontinuity must be adopted and originally analytical solution will have to include numerical procedure.

Dynamic response to moving masses of rectangular plates with general boundary conditions and resting on variable winkler foundation

Awodola,T. O.; Oni,S. T.
Fonte: Associação Brasileira de Ciências Mecânicas Publicador: Associação Brasileira de Ciências Mecânicas
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/03/2013 EN
Relevância na Pesquisa
56.56%
The dynamic response to moving masses of rectangular plates with general classical boundary conditions and resting on variable Winkler elastic foundation is investigated in this work. The governing fourth order partial differential equation is solved using a technique based on separation of variables, the modified method of Struble and the integral transformations. Numerical results in plotted curves are then presented. The results show that as the value of the rotatory inertia correction factor Ro increases, the response amplitudes of the plate decrease and that, for fixed value of Ro, the displacements of the plate decrease as the foundation modulus Fo increases for the variants of the classical boundary conditions considered. The results also show that for fixed Ro and Fo, the transverse deflections of the rectangular plates under the actions of moving masses are higher than those when only the force effects of the moving load are considered. For the rectangular plate, for the same natural frequency, the critical speed for moving mass problem is smaller than that of the moving force problem for all variants of classical boundary conditions, that is, resonance is reached earlier in moving mass problem than in moving force problem. When Fo and Ro increase...

Vibration of plate on foundation with four edges free by finite cosine integral transform method

Zhong,Yang; Zhao,Xue-feng; Liu,Heng
Fonte: Associação Brasileira de Ciências Mecânicas Publicador: Associação Brasileira de Ciências Mecânicas
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/10/2014 EN
Relevância na Pesquisa
36.25%
The analytical solutions for the natural frequencies and mode shapes of the rectangular plate on foundation with four edges free is presented by using the finite cosine integral transform method. In the analysis procedure, the classical Kirchhoff rectangular plate is considered and the foundation is modelled as the Winkler elastic foundation. Because only are the basic dynamic elasticity equations of the thin plate on elastic foundation adopted, it is not need prior to select the deformation function arbitrarily. Therefore, the solution developed by present paper is reasonable and theoretical. In order to illuminate the correction of formulations, the numerical results are also presented to comparing with that of the other references.

Transient loss of consciousness in pediatric recipients of dimethylsulfoxide (DMSO)-cryopre-served peripheral blood stem cells independent of morphine co-medication

Schlegel, Paul G.; Wölfl, Matthias; Schick, Judith; Winkler, Beate; Eyrich, Matthias
Fonte: Ferrata Storti Foundation Publicador: Ferrata Storti Foundation
Tipo: Artigo de Revista Científica
EN
Relevância na Pesquisa
25.94%

Mixed model approaches for the identification of QTLs within a maize hybrid breeding program

van Eeuwijk, Fred A.; Boer, Martin; Totir, L. Radu; Bink, Marco; Wright, Deanne; Winkler, Christopher R.; Podlich, Dean; Boldman, Keith; Baumgarten, Andy; Smalley, Matt; Arbelbide, Martin; ter Braak, Cajo J. F.; Cooper, Mark
Fonte: Springer-Verlag Publicador: Springer-Verlag
Tipo: Artigo de Revista Científica
EN
Relevância na Pesquisa
25.94%
Two outlines for mixed model based approaches to quantitative trait locus (QTL) mapping in existing maize hybrid selection programs are presented: a restricted maximum likelihood (REML) and a Bayesian Markov Chain Monte Carlo (MCMC) approach. The methods use the in-silico-mapping procedure developed by Parisseaux and Bernardo (2004) as a starting point. The original single-point approach is extended to a multi-point approach that facilitates interval mapping procedures. For computational and conceptual reasons, we partition the full set of relationships from founders to parents of hybrids into two types of relations by defining so-called intermediate founders. QTL effects are defined in terms of those intermediate founders. Marker based identity by descent relationships between intermediate founders define structuring matrices for the QTL effects that change along the genome. The dimension of the vector of QTL effects is reduced by the fact that there are fewer intermediate founders than parents. Furthermore, additional reduction in the number of QTL effects follows from the identification of founder groups by various algorithms. As a result, we obtain a powerful mixed model based statistical framework to identify QTLs in genetic backgrounds relevant to the elite germplasm of a commercial breeding program. The identification of such QTLs will provide the foundation for effective marker assisted and genome wide selection strategies. Analyses of an example data set show that QTLs are primarily identified in different heterotic groups and point to complementation of additive QTL effects as an important factor in hybrid performance.

Gene expression factors as predictors of genetic risk and survival in chronic lymphocytic leukemia

Kienle, Dirk; Benner, Axel; Läufle, Carolin; Winkler, Dirk; Schneider, Christof; Bühler, Andreas; Zenz, Thorsten; Habermann, Annett; Jäger, Ulrich; Lichter, Peter; Dalla-Favera, Riccardo; Döhner, Hartmut; Stilgenbauer, Stephan
Fonte: Ferrata Storti Foundation Publicador: Ferrata Storti Foundation
Tipo: Artigo de Revista Científica
EN
Relevância na Pesquisa
25.94%

Protein expression analysis of chronic lymphocytic leukemia defines the effect of genetic aberrations and uncovers a correlation of CDK4, P27 and P53 with hierarchical risk

Winkler, Dirk; Schneider, Christof; Zucknick, Manuela; Bögelein, Daniela; Schulze, Kerstin; Zenz, Thorsten; Mohr, Julia; Philippen, Angela; Huber, Henriette; Bühler, Andreas; Habermann, Annett; Benner, Axel; Döhner, Hartmut; Stilgenbauer, Stephan; Mert
Fonte: Ferrata Storti Foundation Publicador: Ferrata Storti Foundation
Tipo: Artigo de Revista Científica
EN
Relevância na Pesquisa
25.94%

Genetic Analysis of Cortical Thickness and Fractional Anisotropy of Water Diffusion in the Brain

Kochunov, Peter; Glahn, David C.; Nichols, Thomas E.; Winkler, Anderson M.; Hong, Elliot L.; Holcomb, Henry H.; Stein, Jason L.; Thompson, Paul M.; Curran, Joanne E.; Carless, Melanie A.; Olvera, Rene L.; Johnson, Matthew P.; Cole, Shelley A.; Kochunov, V
Fonte: Frontiers Research Foundation Publicador: Frontiers Research Foundation
Tipo: Artigo de Revista Científica
Publicado em 19/10/2011 EN
Relevância na Pesquisa
25.94%
Objectives: The thickness of the brain’s cortical gray matter (GM) and the fractional anisotropy (FA) of the cerebral white matter (WM) each follow an inverted U-shape trajectory with age. The two measures are positively correlated and may be modulated by common biological mechanisms. We employed four types of genetic analyses to localize individual genes acting pleiotropically upon these phenotypes. Methods: Whole-brain and regional GM thickness and FA values were measured from high-resolution anatomical and diffusion tensor MR images collected from 712, Mexican American participants (438 females, age = 47.9 ± 13.2 years) recruited from 73 (9.7 ± 9.3 individuals/family) large families. The significance of the correlation between two traits was estimated using a bivariate genetic correlation analysis. Localization of chromosomal regions that jointly influenced both traits was performed using whole-genome quantitative trait loci (QTL) analysis. Gene localization was performed using SNP genotyping on Illumina 1M chip and correlation with leukocyte-based gene-expression analyses. The gene-expressions were measured using the Illumina BeadChip. These data were available for 371 subjects. Results: Significant genetic correlation was observed among GM thickness and FA values. Significant logarithm of odds (LOD ≥ 3.0) QTLs were localized within chromosome 15q22–23. More detailed localization reported no significant association (p < 5·10−5) for 1565 SNPs located within the QTLs. Post hoc analysis indicated that 40% of the potentially significant (p ≤ 10−3) SNPs were localized to the related orphan receptor alpha (RORA) and NARG2 genes. A potentially significant association was observed for the rs2456930 polymorphism reported as a significant GWAS finding in Alzheimer’s disease neuroimaging initiative subjects. The expression levels for RORA and ADAM10 genes were significantly (p < 0.05) correlated with both FA and GM thickness. NARG2 expressions were significantly correlated with GM thickness (p < 0.05) but failed to show a significant correlation (p = 0.09) with FA. Discussion: This study identified a novel...

Hygrothermomagnetoelectroelastic analysis of a functionally graded magnetoelectroelastic hollow sphere resting on an elastic foundation

Saadatfar, M.; Aghaie-Khafri, M.
Fonte: IOP Publishing Publicador: IOP Publishing
Tipo: Artigo de Revista Científica Formato: 13 pages
Relevância na Pesquisa
36.2%
Static behavior of a functionally graded magnetoelectroelastic hollow sphere subjected to hygrothermal loading in the spherically symmetric state is studied. The sphere could be rested on a Winkler elastic foundation on the inner and/or outer surfaces. It is assumed that the material properties obey a power law in the radial direction. Considering the axisymmetric heat conduction and moisture diffusion equations, temperature and moisture concentration distributions within the radius of the sphere are achieved. The governing coupled differential equations are exactly solved. Numerical examples are discussed in detail to show the significant influences of inhomogeneity index, hygrothermal loading, elastic foundation and electromagnetic boundary conditions on the static behavior of a functionally graded magnetoelectroelastic hollow sphere.

Supersaturating silicon with transition metals by ion implantation and pulsed laser melting

Recht, Daniel; Smith, Matthew J.; Charnvanichborikarn, Supakit; Sullivan, Joseph T.; Winkler, Mark T.; Mathews, Jay; Warrender, Jeffrey M.; Buonassisi, Tonio; Williams, James S.; Gradečak, Silvija; Aziz, Michael J.
Fonte: American Institute of Physics Publicador: American Institute of Physics
Tipo: Artigo de Revista Científica Formato: 8 pages
Relevância na Pesquisa
26.15%
We investigate the possibility of creating an intermediate band semiconductor by supersaturating Si with a range of transition metals (Au, Co, Cr, Cu, Fe, Pd, Pt, W, and Zn) using ion implantation followed by pulsed laser melting (PLM). Structural characterization shows evidence of either surface segregation or cellular breakdown in all transition metals investigated, preventing the formation of high supersaturations. However, concentration-depth profiling reveals that regions of Si supersaturated with Au and Zn are formed below the regions of cellular breakdown. Fits to the concentration-depth profile are used to estimate the diffusive speeds, v D, of Au and Zn, and put lower bounds on v D of the other metals ranging from 10² to 10⁴ m/s. Knowledge of v D is used to tailor the irradiation conditions and synthesize single-crystal Si supersaturated with 10¹⁹ Au/cm³ without cellular breakdown. Values of v D are compared to those for other elements in Si. Two independent thermophysical properties, the solute diffusivity at the melting temperature, D s(T m), and the equilibrium partition coefficient, k e, are shown to simultaneously affect v D. We demonstrate a correlation between v D and the ratio D s(T m)/k e ⁰·⁶⁷, which is exhibited for Group III...

Dynamic behaviour under moving concentrated masses of simply supported rectangular plates resting on variable Winkler elastic foundation

Oni,S. T.; Awodola,T. O.
Fonte: Associação Brasileira de Ciências Mecânicas Publicador: Associação Brasileira de Ciências Mecânicas
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/01/2011 EN
Relevância na Pesquisa
46.65%
The response of simply supported rectangular plates carrying moving masses and resting on variable Winkler elastic foundations is investigated in this work. The governing equation of the problem is a fourth order partial differential equation. In order to solve this problem, a technique based on separation of variables is used to reduce the governing fourth order partial differential equations with variable and singular coefficients to a sequence of second order ordinary differential equations. For the solutions of these equations, a modification of the Struble's technique and method of integral transformations are employed. Numerical results in plotted curves are then presented. The results show that response amplitudes of the plate decrease as the value of the rotatory inertia correction factor R0 increases. Furthermore, for fixed value of R0, the displacements of the simply supported rectangular plates resting on variable elastic foundations decrease as the foundation modulus F0 increases. The results further show that, for fixed R0 and F0, the transverse deflections of the rectangular plates under the actions of moving masses are higher than those when only the force effects of the moving load are considered. Therefore, the moving force solution is not a safe approximation to the moving mass problem. Hence...

Flexural motions under moving concentrated masses of elastically supported rectangular plates resting on variable winkler elastic foundation

Awodola,T. O.
Fonte: Associação Brasileira de Ciências Mecânicas Publicador: Associação Brasileira de Ciências Mecânicas
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/01/2014 EN
Relevância na Pesquisa
46.63%
The flexural motions of elastically supported rectangular plates carrying moving masses and resting on variable Winkler elastic foundations is investigated in this work In order to solve the fourth order partial differential equation governing the problem, a technique based on separation of variables is used to reduce the governing fourth order partial differential equations with variable and singular coefficients to a sequence of second order ordinary differential equations. These equations are then solved using a modification of the Struble's technique and method of integral transformations. Numerical results are then presented in plotted curves. The results show that response amplitudes of the plate decrease as the value of the rotatory inertia correction factor Ro increases and for fixed value of Ro, the displacements of the elastically supported rectangular plates resting on variable elastic foundations decrease as the foundation modulus Fo increases. Also, for fixed Ro and Fo, the transverse deflections of the rectangular plates under the actions of moving masses are higher than those when only the force effects of the moving load are considered. Therefore, the moving force solution is not a safe approximation to the moving mass problem. Hence...

On the asymptotic derivation of Winkler-type energies from 3D elasticity

Baldelli, Andrés A León; Bourdin, Blaise
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Publicado em 02/10/2014
Relevância na Pesquisa
26.42%
We show how bilateral, linear, elastic foundations (i.e. Winkler foundations) often regarded as heuristic, phenomenological models, emerge asymptotically from standard, linear, three-dimensional elasticity. We study the parametric asymptotics of a non-homogeneous linearly elastic bi-layer attached to a rigid substrate as its thickness vanishes, for varying thickness and stiffness ratios. By using rigorous arguments based on energy estimates, we provide a first rational and constructive justification of reduced foundation models. We establish the variational weak convergence of the three-dimensional elasticity problem to a two-dimensional one, of either a "membrane over in-plane elastic foundation", or a "plate over transverse elastic foundation". These two regimes are function of the only two parameters of the system, and a phase diagram synthesizes their domains of validity. Moreover, we derive explicit formulae relating the effective coefficients of the elastic foundation to the elastic and geometric parameters of the original three-dimensional system.; Comment: 21 pages, 2 figures

Buckling patterns of complete spherical shells filled with an elastic medium under external pressure

Sato, Motohiro; Wadee, M. Ahmer; Iiboshi, Kohtaroh; Sekizawa, Takafumi; Shima, Hiroyuki
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Publicado em 10/03/2011
Relevância na Pesquisa
26.08%
The critical buckling characteristics of hydrostatically pressurized complete spherical shells filled with an elastic medium are demonstrated. A model based on small deflection thin shell theory, the equations of which are solved in conjunction with variational principles, is presented. In the exact formulation, axisymmetric and inextensional assumptions are not used initially and the elastic medium is modelled as a Winkler foundation, i.e., using uncoupled radial springs with a constant foundation modulus that is independent of wave numbers of shell buckling modes. Simplified approximations based on a Rayleigh-Ritz approach are also introduced for critical buckling pressure and mode number with a considerable degree of accuracy. Characteristic modal shapes are demonstrated for a wide range of material and geometric parameters. A phase diagram is established to obtain the requisite thickness to radius, and stiffness ratios for a desired mode profile. The present exact formulation can be readily extended to apply to more general cases of non-axisymmetric buckling problems.; Comment: 24 pages, 9 figures

Nano and viscoelastic Beck's column on elastic foundation

Atanackovic, Teodor M.; Bouras, Yanni; Zorica, Dusan
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Publicado em 12/08/2014
Relevância na Pesquisa
26.08%
Beck's type column on Winkler type foundation is the subject of the present analysis. Instead of the Bernoulli-Euler model describing the rod, two generalized models will be adopted: Eringen non-local model corresponding to nano-rods and viscoelastic model of fractional Kelvin-Voigt type. The analysis shows that for nano-rod, the Herrmann-Smith paradox holds while for viscoelastic rod it does not.

Dynamic behavior of rocking structures allowed to uplift

Psycharis, Ioannis N.
Fonte: California Institute of Technology Publicador: California Institute of Technology
Tipo: Report or Paper; PeerReviewed Formato: application/pdf
Publicado em 01/01/1981
Relevância na Pesquisa
26.23%
Strong shaking of structures during large earthquakes may result in some cases in partial separation of the base of the structure from the sail. This phenomenon of uplifting, which can affect the dynamic behavior of the structure significantly, even if the amount of uplift is small, is examined in this thesis. First the case of a rocking rigid block is investigated and then more complicated, flexible superstructures are introduced. Two foundation models which permit uplift are considered: the Winkler foundation and the much simpler "two-spring" foundation. Several energy dissipating mechanisms are also introduced into these models. It is shown that an equivalence between these two models for the foundation can be established, so that one can always work with the much simpler two-spring foundation. In this way complete analytical solutions can be derived in most cases. Moreover, simple approximate methods for the calculation of the apparent fundamental period of the rocking system are developed and simplified methods of analysis are proposed. In general, uplift leads to a softer vibrating system which behaves nonlinearly, although the response is composed of a sequence of linear responses. As a result, the apparent fundamental resonant frequency of the uplifting system is always less than the fundamental resonant frequency of both the soil-structure interacting system...

Estudo do problema de interação solo-estrutura aplicado ao projeto de fundações para a ponte sobre o Rio Anhanduí na BR 262/MS

Oliveira, Ezequias Borges de
Fonte: Joinville, SC Publicador: Joinville, SC
Tipo: Trabalho de Conclusão de Curso Formato: 94 f.
PT_BR
Relevância na Pesquisa
26.16%
TCC (graduação) - Universidade Federal de Santa Catarina. Campus Joinville. Engenharia de Infraestrutura.; Este trabalho tem por objetivo realizar um estudo da interação solo-estrutura em fundações profundas submetidas a carregamentos laterais. Neste trabalho estudou-se o caso da ponte sobre o Rio Anhanduí, na BR 262/MS, especialmente as condições geológicas e geotécnicas em que se encontra esta estrutura. Um perfil estratigráfico foi idealizado a partir de sondagens mistas efetuadas no local e parâmetros de comportamento foram derivados para os solos e rochas que ocorrem na área. A partir destas informações foram modeladas curvas p-y para observar e evidenciar o comportamento não linear do solo para um conjunto de estacas raiz. O método utilizado para determinar o comportamento da interação solo-estrutura foi a solução de Reese e Matlock (1956) para o modelo de Winkler, que aborda o solo como um conjunto de molas lineares elásticas independentes entre si. Os resultados demonstraram que os esforços cortantes e momentos máximos ocorrem em profundidade, atestando, desta forma, a necessidade de estacas integralmente armadas. De forma complementar, foi avaliada a capacidade de carga em rocha, pelos métodos de Kulhawy e Carter (1992) e pelo método de Terzaghi...