Is General Relativity a simplified theory?

IARD 8th Biennial Conference on Classical and Quantum Relativistic Dynamics of Particles and Fields - Galileo Galilei Inst Theoret Phys (GGI), Florence, ITALY - MAY 29-JUN 01, 2012. Edited by:Horowitz, LP

Choice under Risk : Theory and Applications

Es útil para estudiantes de postgrado (Master y Doctorado) en cursos de Economía o de Microeconomía en los que se analicen problemas de Decisión en condiciones de Riesgo o Incertidumbre. El documento comienza explicando la Teoría de la Utilidad Esperada. A continuación se estudian la aversión al riesgo, los coeficientes de aversión absoluta y relativa al riesgo, la relación “más averso que” entre agentes económicos y los efectos riqueza sobre las decisiones en algunas relaciones de preferencia utilizadas frecuentemente en el análisis económico. La sección 4 se centra en la comparación entre alternativas arriesgadas en términos de rendimiento y riesgo, considerando la dominancia estocástica de primer y segundo orden y algunas extensiones posteriores de esas relaciones de orden. El documento concluye con doce ejercicios resueltos en los que se aplican los conceptos y resultados expuestos en las secciones anteriores a problemas de decisión en varios contextos

New Strain Gradient Theory And Analysis

A new strain gradient theory which is based on energy nonlocal model is proposed in this paper, and the theory is applied to investigate the size effects in thin metallic wire torsion, ultra-thin beam bending and micro-indentation of polycrystalline copper. First, an energy nonlocal model is suggested. Second, based on the model, a new strain gradient theory is derived. Third, the new theory is applied to analyze three representative experiments.

An extension of the two dimensional JKR theory to the case with a large contact width

In the Hertz and JKR theories, parabolic assumptions for the rounded profiles of the sphere or cylinder are adopted under the condition that the contact radius (width) should be very small compared to the radius of the sphere or cylinder. However, a large contact radius (width) is often found in experiments even under a zero external loading. We aim at extending the plane strain JKR theory to the case with a large contact width. The relation between the external loading and the contact width is given. Solutions for the Hertz, JKR and rounded-profile cases are compared and analyzed. It is found that when the ratio of a/R is approximately larger than about 0.4, the parabolic assumptions in the Hertz and JKR theories are no longer valid and the exact rounded profile function should be used.

The elasto-damage theory of the components assembling model

The potential energy in materials is well approximated by pair functional which is composed of pair potentials and embedding energy. During calculating material potential energy, the orientational component and the volumetric component are derived respectively from pair potentials and embedding energy. The sum of energy of all these two kinds of components is the material potential. No matter how microstructures change, damage or fracture, at the most level, they are all the changing and breaking atomic bonds. As an abstract of atomic bonds, these components change their stiffness during damaging. Material constitutive equations have been formulated by means of assembling all components' response functions. This material model is called the component assembling model. Theoretical analysis and numerical computing indicate that the proposed model has the capacity of reproducing some results satisfactorily, with the advantages of great conceptual simplicity, physical explicitness, and intrinsic induced anisotropy, etc.