El relieve de la comarca de La Jacetania

Peer reviewe

Representación de materiales viscoelásticos con aplicación a estructuras de hormigón

Se presenta una formulación para las relaciones constitutivas viscoelásticas de sólidos estructurales basada en el concepto de variables de estado, enfatizando algunas características particulares del hormigón. Combinando estas ecuaciones con un método variacional adecuado para representar procesos incrementales en deformaciones finitas se obtiene la correspondiente formulación de elementos finitos que es aplicada a problemas de estabilidad, de estructuras no homogéneas y de relajación térmica.A unified foriilulation for the viscoelastic constltutive relations of structural solids based in the state space concept with emphasis in concrete-like materials is presented. The equations are combined with a variational principle adequate for finite deformations in order to obtain a Finite Eleinents formulation, which is applied to stability problexqs, to non-homogeneous structures and to the analysis of thermal relaxation.Peer Reviewe

Probabilidades de precipitación anual y estival en Navarra.

Sin resume

Tratamento do problema de contato-impacto entre corpos flexíveis em grandes deformações pelo método dos elementos finitos

O tratamento do problema de contato entre corpos flexíveis foi implementado no módulo METAFOR4, que permite o tratamento de problemas de conformacáo mecanica. O presente algoritmo emprega o método da penalidade para o cálculo de forcas de contato. Os elementos de contato sáo percorridos duas vezes em cada passo de tempo para que seja assegurada a deteccáo de todas as formas de interpenetracao. O algoritmo apresentou-se extremamente robusto. Um exemplo de impacto entre um tubo e uma placa é mostrado.The treatment of the contact problem between flexible bodies has been implemented in the METAFOR modulus4, which allows the treatment of metal forming problems. The described algorithm uses the penalty method for the calculation of the contact forces. The contact elements are checked twice at each time step to assure the detection of al1 forms of penetration. The algorithm demonstrated to be extremely robust. An example of impact between a tube and a plate is given.Peer Reviewe

Tratamento do problema de contato-impacto entre corpos flexíveis em grandes deformações pelo método dos elementos finitos

O tratamento do problema de contato entre corpos flexíveis foi implementado no módulo METAFOR4, que permite o tratamento de problemas de conformacáo mecanica. O presente algoritmo emprega o método da penalidade para o cálculo de forcas de contato. Os elementos de contato sáo percorridos duas vezes em cada passo de tempo para que seja assegurada a deteccáo de todas as formas de interpenetracao. O algoritmo apresentou-se extremamente robusto. Um exemplo de impacto entre um tubo e uma placa é mostrado.The treatment of the contact problem between flexible bodies has been implemented in the METAFOR modulus4, which allows the treatment of metal forming problems. The described algorithm uses the penalty method for the calculation of the contact forces. The contact elements are checked twice at each time step to assure the detection of al1 forms of penetration. The algorithm demonstrated to be extremely robust. An example of impact between a tube and a plate is given.Peer Reviewe

Análise viscoelástica de estruturas laminadas mediante emprego da inversao numérica da transformada de Laplace

Este trabalho focaliza a análise viscoelástica de estruturas laminadas em material compósito de matriz polimérica, propondo o emprego de métodos de inversa0 numérica da transformada de Laplace numa formulacao adaptada ao método dos elementos finitos. Nesta abordagem alternativa,as equacóes constitutivas viscoelásticas, formuladas no plano complexo da variável de transformacáo S , reduzem o problema a urna análise elástica equivalente. As solu~óesc omplexas sáo entiio retornadas ao plano físico para o valor de tempo desejado, dispensando processos incrementais. Exemplos de aplicaqóes siio executados comparando-se os resultados do Método da Transformada de Laplace com o Método das Variáveis de Estado que trata o problema viscoelástico de forma incremental.The viscoelastic analysis of laminated structures of polymeric matrix composite materials using Laplace transform is the objective of this work. The inverse of the Laplace transform is carried out using numerical methods adapted to a finite element method formulation. In this alternative aproach, as the constitutive equations are formulated on the complex plane in the transformation variable 'S', the viscoelasti~problemre duces to an equivalent elastic one. The complex solutions are then sent back to the physical plane for the desired time value, dispensing incremental processes. Examples of aplications compairing results obtained with the Laplace Transformation Method and the State Variables Method (that treats the viscoelastic problem in an incremental form) are presented.Peer Reviewe

Scintillation efficiency of liquid argon in low energy neutron-argon scattering

Experiments searching for weak interacting massive particles with noble gases such as liquid argon require very low detection thresholds for nuclear recoils. A determination of the scintillation efficiency is crucial to quantify the response of the detector at low energy. We report the results obtained with a small liquid argon cell using a monoenergetic neutron beam produced by a deuterium-deuterium fusion source. The light yield relative to electrons was measured for six argon recoil energies between 11 and 120 keV at zero electric drift field.Comment: 21 pages, 19 figures, 4 table

Salmonella contamination on pork carcasses: a study of critical points

The aim of the present study was to determine the frequency and distribution of Salmonella contaminations throughout the slaughtering process of pigs. The investigation was carried out in two slaughterhouses that were visited four times each on different days

Effect of an acidified diet on Salmonella prevalence during the last term of fattening period

The objective of this study was to determine the effect of the acidification of pelleted feed on the carriage and seropositivity against Salmonella in finisher pigs of a commercial herd. Three different diets were assayed: 0.8% formic acid (group 1); 0.4% lactic acid plus 0.4% formic acid (group 2) and a feedstuff without additives (group 3). one thousand pigs were included in each treatment that was administered from 19 to 26 weeks of age

Nucleation and Growth of the Zn-Fe Alloy from a Chloride Electrolyte

In this study, the kinetics of Zn-Fe codeposition was investigated in chloride acidic solution using cyclic voltammetry. Anomalous codeposition is detected and this mechanism depends on the Zn(II) / Fe(II) concentration ratio in the electrolytic bath. The study of early stages of electrodeposition showed that Zn- Fe follows a theoretical response to instantaneous nucleation evolves into a progressive nucleation according to the model of Scharifker and Hills. The morphology and structure of the coatings is discussed using characterization techniques. Dense, uniform, and singlephased Zn-Fe coatings could be obtained with a Zn-Fe ratio of 1/3. When you are citing the document, use the following link http://essuir.sumdu.edu.ua/handle/123456789/3531