Solución de un modelo simplificado de publicidad usando técnicas de control óptimo

This article presents a simplification to the distributed advertising model, formulating it as a family of optimal control problems with concentrated parameters. Two simplified variants are studied: linear and nonlinear. An analytical solution derived from the principle of maximum is provided for the linear model. To solve the nonlinear model, a numerical algorithm is built based on two unconventional formulas for increasing the objective functional.En este artículo se presenta una simplificación al modelo distribuido de publicidad, formulándolo como una familia de problemas de control óptimo con parámetros concentrados. Se estudian dos variantes simplificadas: lineal y no lineal. Para el modelo lineal se proporciona una solución analítica derivada del principio de máximo. Para resolver el modelo no lineal se construye un algoritmo numérico basado en dos fórmulas no convencionales del incremento de la funcional objetivo

Possible canonical distributions for finite systems with nonadditive energy

It is shown that a small system in thermodynamic equilibrium with a finite thermostat can have a q-exponential probability distribution which closely depends on the energy nonextensivity and the particle number of the thermostat. The distribution function will reduce to the exponential one at the thermodynamic limit. However, the nonextensivity of the system should not be neglected.Comment: 13 pages, 4 figure

Faster-than-c signals, special relativity, and causality

Motivated by the recent attention on superluminal phenomena, we investigate the compatibility between faster-than-c propagation and the fundamental principles of relativity and causality. We first argue that special relativity can easily accommodate -- indeed, does not exclude -- faster-than-c signalling at the kinematical level. As far as causality is concerned, it is impossible to make statements of general validity, without specifying at least some features of the tachyonic propagation. We thus focus on the Scharnhorst effect (faster-than-c photon propagation in the Casimir vacuum), which is perhaps the most plausible candidate for a physically sound realization of these phenomena. We demonstrate that in this case the faster-than-c aspects are ``benign'' and constrained in such a manner as to not automatically lead to causality violations.Comment: Plain LaTeX2E; 25 pages; 4 embedded figures (LaTeX pictures). V2: Some discussion clarified, minor rearrangements, references updated, no change in physics conclusions. To appear in Annals of Physic

Deriving relativistic momentum and energy

We present a new derivation of the expressions for momentum and energy of a relativistic particle. In contrast to the procedures commonly adopted in textbooks, the one suggested here requires only the knowledge of the composition law for velocities along one spatial dimension, and does not make use of the concept of relativistic mass, or of the formalism of four-vectors. The basic ideas are very general and can be applied also to kinematics different from the Newtonian and Einstein ones, in order to construct the corresponding dynamics.Comment: 15 pages, 2 figure

Reflection of circularly polarized waves at the boundary of a nonlinear medium

[No abstract available

Entropy as a dynamical variable

[No abstract available