The role of nonequilibrium thermo-mechanical statistics in modern technologies and industrial processes: an overview

Abstract

The nowadays notable development of all the modern technology, fundamental for the progress and well being of world society, imposes a great deal of stress in the realm of basic Physics, more precisely on ThermoStatistics. We do face situations in electronics and optoelectronics involving physical-chemical systems farremoved-from equilibrium, where ultrafast (in pico-and femto-second scale) and non-linear processes are present. Further, we need to be aware of the rapid unfolding of nano-technologies and use of low-dimensional systems (e.g., nanometric quantum wells and quantum dots in semiconductor heterostructures). All together this demands having an access to a Statistical Mechanics being efficient to deal with such requirements. It is worth noticing that the renowned Ryogo Kubo once stated that "statistical mechanics has been considered a theoretical endeavor. However, statistical mechanics exists for the sake of the real world, not for fictions. Further progress can only be hoped by close cooperation with experiment". Moreover, one needs to face the study of soft matter and fluids with complex structures (usually of the average self-affine fractal-like type). This is relevant for technological improvement in industries like, for example, that of polymers, petroleum, cosmetics, food, electronics and photonics (conducting polymers and glasses), in medical engineering, etc. It is then required to introduce a thermo-hydrodynamics going well beyond the classical (Onsagerian) one. Moreover, in the both type of situations above mentioned there often appear difficulties of description and objectivity (existence of so-called "hidden constraints"), which impair the proper application of the conventional ensemble approach used in the general, logically and physically sound, and well established Boltzmann-Gibbs statistics. A tentative to partially overcome such difficulties consists in resorting to non-conventional approaches. Here we briefly describe the construction of a Non-Equilibrium Statistical Ensemble Formalism (NESEF) that can deal, within a certain degree of success, with the situations above described. Several particular instances involving experimental observations and measurements in the area of semiconductor physics and in physics of fluids, which were analyzed in the context of the theory, are summarized. They comprise the cases of ultrafast optical spectroscopy; optical and transport processes in low-dimensional complex semiconductors; nonlinear transport in doped highly-polar semiconductors (of use in "blue diodes") under moderate to high electric fields; nonlinear higher-order thermo-hydrodynamics in fluids under driven flow, in normal solutions and in complex situations as in solutions of polymers, micelles, DNA, and in microbatteries.

Sobre a conexão entre alguns modelos físicos não-lineares

“…Material em língua portuguesa que trate fenômenos não-lineares e sólitons pode ser encontrado, como em [25][26][27][28][29], mas não em volume compatível com sua importância e ocorrendo predominantemente na forma de dissertações e teses,por exemplo [30][31][32][33]. Não obstante, vale destacar que a comunidade científica brasileira tem sido bastante ativa nestaárea, inserindo-a em universo bastante abrangente que inclui desde a física de plasmas [34], mecânica estatística, [35][36][37][38][39] e.g., equações diferenciais [40][41][42][43], física matemática [44][45][46][47], altas energias [48,49], etc. Logo, em meio a tantas ocorrências, reforçamos a ideia de que os sistemas não-lineares correspondem a umaárea importante e ativa, merecendo atenção por parte dos estudantes.…”

Complexidade, auto-organização e informação em sistemas dinâmicos

“…Em um primeiro passo parece ser conveniente testar idéias, conceitos, e teorias aplicadas a sistemas que admitam um tratamento mais acessível, tanto no nível teórico como, e especialmente, no experimental. Um caso particular e relevanteé o dos semicondutores, os quais -por causa de um evidente interesse tecnológico -são objeto de uma mui extensa pesquisa [29], e outro casoé o de sistemas biológicos modelados [30].…”

“…Rolf Landauer em "Information is physical" [Physics Today, May 1991, pp. [23][24][25][26][27][28][29], tem dito que: "A Termodinâmica surgiu no Século XIX a partir da tentativa de compreender os limites de desempenho das máquinas de vapor (no início da Revolução Industrial), de forma a antecipar todas as possíveis invenções. Claude Shannon, durante a Segunda Guerra Mundial do Século XX, analisou os limites dos canais de comunicação (dando inicioà depois chamada teoria da informação [70,71]).…”

Ultrafast dynamics of carriers and phonons of photoinjected double-plasma in aluminium nitride

“…The NE-SOM is a powerful formalism that seems to offer an elegant and concise way for an analytical treatment in the theory of irreversible processes, adequate to deal with a large class of experimental situations, and physically clear picture of irreversible processes. The NESOM is also practical and efficient in the study of the optical and carrier dynamics in semiconductors [36][37][38][39][40][41][42]. More specifically, a Non-Equilibrium Quantum Kinetic Theory [43] derived from NESOM was used in this paper.…”