General Relationship Between Contact Stiffness, Contact Depth, and Mechanical Properties for Indentation in Linear Viscoelastic Solids Using Axisymmetric Indenters of Arbitrary Profiles

We derive a relationship between the initial unloading slope, contact depth, and the instantaneous relaxation modulus for indentation in linear viscoelastic solids by a rigid indenter with an arbitrary axisymmetric smooth profile. Although the same expression is well known for indentation in elastic and in elastic-plastic solids, we show that it is also true for indentation in linear viscoelastic solids, provided that the unloading rate is sufficiently fast. Furthermore, the same expression holds true for both fast loading and unloading. These results should provide a sound basis for using the relationship for determining properties of viscoelastic solids using indentation techniques.

General Solution to Two-Dimensional Nonslipping JKR Model with a Pulling Force in an Arbitrary Direction

In this paper, a generalized JKR model is investigated, in which an elastic cylinder adhesively contacts with an elastic half space and the contact region is assumed to be perfect bonding. An external pulling force is acted on the cylinder in an arbitrary direction. The contact area changes during the pull-off process, which can be predicted using the dynamic Griffith energy balance criterion as the contact edge shifts. Full coupled solution with an oscillatory singularity is obtained and analyzed by numerical calculations. The effect of Dundurs' parameter on the pull-off process is analyzed, which shows that a nonoscillatory solution can approximate the general one under some conditions, i.e., larger pulling angle (pi/2 is the maximum value), smaller a/R or larger nondimensional parameter value of Delta gamma/E*R. Relations among the contact half width, the external pulling force and the pulling angle are used to determine the pull-off force and pull-off contact half width explicitly. All the results in the present paper as basic solutions are helpful and applicable for experimenters and engineers.

Estudio general de las politicas vigentes en cuarentena animal de Nicaragua, en los puestos fronterizos El Espino y Pe��as Blancas en el periodo de Enero-Mayo 2009

En Nicaragua existen leyes, requisitos, y procedimientos que se aplican, para llevar a cabo la protecci��n agropecuaria a nivel de los puestos fronterizos del pa��s, por eso se propuso este trabajo monogr��fico que lleva por t��tulo "Estudio de las pol��ticas vigentes en cuarentena animal de Nicaragua en los puestos fronterizo El Espino y Pe��as Blancas en el periodo de Enero a Mayo del 2009", el cual se baso en los procedimientos de inspecci��n en cuarentena animal, productos y subproductos seg��n la Ley B��sica de Salud Animal y Sanidad Vegetal (Ley 291). Este estudio se realizo en un periodo de cinco meses mediante la estad��a en dichos puestos, los datos recopilados se obtuvieron de formatos oficiales de la Direcci��n General de protecci��n agropecuaria (DGPSA) dentro de ellos tenemos los certificados zoosanitarios, permisos de importaci��n, formatos de inspecci��n, actas de retenci��n, decomiso, destrucci��n y rechazo. Se confirmo que los puestos cumplen con los procedimientos de inspecci��n cuarentenaria tomando en cuenta la ley 291 y manuales de inspecci��n. Durante la etapa de investigaci��n constatamos que existe una gran discrepancia entre el Puesto de El Espino y Pe��as Blancas, tanto en el trabajo a realizar como en instalaciones, no obstante. ambos puestos carecen de instalaciones adecuadas para la inspecci��n, cuentan con bajo presupuesto y poco personal, pero a pesar de las cond��ciones en que se encuentran los inspectores realizan un arduo esfuerzo por efectuar su trabajo. Se recomienda que todos los puestos cuarentenarios del pa��s cumplan con las condiciones adecuadas, infraestructuras seguras y personal profesionalmente capacitado y debidamente actualizado con las enfermedades ex��ticas que puedan ingresar al pa��s.

The scattering of general SH plane wave by interface crack between two dissimilar viscoelastic bodies

The scattering of general SH plane wave by an interface crack between two dissimilar viscoelastic bodies is studied and the dynamic stress,intensity factor at the crack-tip is computed. The scattering problem can be decomposed into two problems: one is the reflection and refraction problem of general SH plane waves at perfect interface (with no crack); another is the scattering problem due to the existence of crack. For the first problem, the viscoelastic wave equation, displacement and stress continuity conditions across the interface are used to obtain the shear stress distribution at the interface. For the second problem, the integral transformation method is used to reduce the scattering problem into dual integral equations. Then, the dual integral equations are transformed into the Cauchy singular integral equation of first kind by introduction of the crack dislocation density function. Finally, the singular integral equation is solved by Kurtz's piecewise continuous function method. As a consequence, the crack opening displacement and dynamic stress intensity factor are obtained. At the end of the paper, a numerical example is given. The effects of incident angle, incident frequency and viscoelastic material parameters are analyzed. It is found that there is a frequency region for viscoelastic material within which the viscoelastic effects cannot be ignored.

Estrategias discursivas y proverbios en la poes��a del Marqu��s de Santillana recopilada en el Cancionero General de 1511

Integran este n��mero de la revista ponencias presentadas en Studia Hispanica Medievalia VIII : Actas de las X Jornadas Internacionales de Literatura Espa��ola Medieval, 2011, y de Homenaje al Quinto Centenario del Cancionero General de Hernando del Castillo.

Sapientia (��ndice general)

Contenido: ��ndice general de autores y materias. A��o I, 1946 - A��o X, 1955

A general design method for electric machines using magnetic circuit model considering the flux saturation problem

This paper proposes an analytical approach that is generalized for the design of various types of electric machines based on a physical magnetic circuit model. Conventional approaches have been used to predict the behavior of electric machines but have limitations in accurate flux saturation analysis and hence machine dimensioning at the initial design stage. In particular, magnetic saturation is generally ignored or compensated by correction factors in simplified models since it is difficult to determine the flux in each stator tooth for machines with any slot-pole combinations. In this paper, the flux produced by stator winding currents can be calculated accurately and rapidly for each stator tooth using the developed model, taking saturation into account. This aids machine dimensioning without the need for a computationally expensive finite element analysis (FEA). A 48-slot machine operated in induction and doubly-fed modes is used to demonstrate the proposed model. FEA is employed for verification.

El Cancioneiro Geral portugu��s y algunas distinciones de su cong��nere, El Cancionero General

Integran este n��mero de la revista ponencias presentadas en Studia Hispanica Medievalia VIII : Actas de las X Jornadas Internacionales de Literatura Espa��ola Medieval, 2011, y de Homenaje al Quinto Centenario del Cancionero General de Hernando del Castillo.

Un impreso po��tico en el cancionero manuscrito EM6 : el pliego suelto 99*RN y el Cancionero General

Integran este n��mero de la revista ponencias presentadas en Studia Hispanica Medievalia VIII : Actas de las X Jornadas Internacionales de Literatura Espa��ola Medieval, 2011, y de Homenaje al Quinto Centenario del Cancionero General de Hernando del Castillo.

Una teor��a general para la ense��anza del derecho civil : una propuesta para el Bicentenario

Resumen: El presente trabajo propone elementos para una reformulaci��n de la ense��anza del Derecho Civil en la Argentina del Bicentenario. Parte del an��lisis del estado actual de la ense��anza en esta rama jur��dica, con especial referencia a sus etapas hist��ricas. Considera luego lo que se denomina ���el modelo del cententario���, con particular atenci��n a la influencia de la modernidad ilustrada y la cultura del C��digo. Eval��a luego la cuesti��n a partir de la tensi��n entre modernidad ilustrada y posmodernidad, proponiendo una alternativa al modelo de ense��anza surgido de la posmodernidad. Como hip��tesis de trabajo propone una lectura de la denominada cultura jur��dica desde los principios del derecho, y aportar as�� una alternativa desde la perspectiva del realismo jur��dico cl��sico.

Sapientia, 1972, Vol. XXVII, n�� 104 (��ndice general)

Contenido: ��ndice general de autores y materias. A��o I, 1946 ��� A��o XXV, 1970

Sequential decision making in general state space models

Many problems in control and signal processing can be formulated as sequential decision problems for general state space models. However, except for some simple models one cannot obtain analytical solutions and has to resort to approximation. In this thesis, we have investigated problems where Sequential Monte Carlo (SMC) methods can be combined with a gradient based search to provide solutions to online optimisation problems. We summarise the main contributions of the thesis as follows. Chapter 4 focuses on solving the sensor scheduling problem when cast as a controlled Hidden Markov Model. We consider the case in which the state, observation and action spaces are continuous. This general case is important as it is the natural framework for many applications. In sensor scheduling, our aim is to minimise the variance of the estimation error of the hidden state with respect to the action sequence. We present a novel SMC method that uses a stochastic gradient algorithm to find optimal actions. This is in contrast to existing works in the literature that only solve approximations to the original problem. In Chapter 5 we presented how an SMC can be used to solve a risk sensitive control problem. We adopt the use of the Feynman-Kac representation of a controlled Markov chain flow and exploit the properties of the logarithmic Lyapunov exponent, which lead to a policy gradient solution for the parameterised problem. The resulting SMC algorithm follows a similar structure with the Recursive Maximum Likelihood(RML) algorithm for online parameter estimation. In Chapters 6, 7 and 8, dynamic Graphical models were combined with with state space models for the purpose of online decentralised inference. We have concentrated more on the distributed parameter estimation problem using two Maximum Likelihood techniques, namely Recursive Maximum Likelihood (RML) and Expectation Maximization (EM). The resulting algorithms can be interpreted as an extension of the Belief Propagation (BP) algorithm to compute likelihood gradients. In order to design an SMC algorithm, in Chapter 8 uses a nonparametric approximations for Belief Propagation. The algorithms were successfully applied to solve the sensor localisation problem for sensor networks of small and medium size.