Evolution of ideal micro-crack system

The ideal micro-cracks are treated with the number-density function; the characteristics of their evolution are investigated; a deterministic model is applied to the discussion of their extension. It is discovered that under certain conditions saturation may occur in the number-density. The main features of the statistical formulation are illustrated by several examples and compared with those observed in experiments.

Statistical modeling of damage evolution in spallation

In order to understand the mechanism of the incipient spallation in rolled metals, a one dimensional statistical mode1 on evolution of microcracks in spallation was proposed. The crack length appears to be the fundamental variable in the statistical description. Two dynamic processes, crack nucleation and growth, were involved in the model of damage evolution. A simplified case was examined and preliminary correlation to experimental observations of spallation was made.

The dynamic evolution of the kepler supernova remnant

been analyzed in detail. The effects ofm icroscopic energy transfer from

Evolution and propagation of density waves on galactic disk .1. General evolution equation of wavelet and discussion of its solution

This paper presents a general self-consistent theory of evolution and propagation of wavelets on the galactic disk. A simplified model for this theory, i. e. the thin transition-layer approximation is proposed.There are three types of solutions to the basic equation governing the evolution of wavelets on the disk: (ⅰ) normal propagating type; (ⅱ) swing type; (ⅲ) general evolving type. The results show that the first two types are applicable to a certain domain on the galactic disk and a certain region of the wave number of wavelets. The third is needed to join the other two types and to yield a coherent total picture of the wave motion. From the present theory, it can be seen that the well-known "swing theory" of the G-L sheet model holds only for a certain class of basic states of galaxies.

Effect of current on the evolution of a solitary wave

In this paper, the effect of current on the evolution of a solitary wave is studied. The governing equation in the far field, KdV equation with variable coefficients, is derived. A solitary wave solution is obtained. The fission of a solitary wave is discussed, and the fissible region on the Q～h2-plane and the criterion of the number of the solitary waves after fission are found.

Evolution and propagation of density waves on galactic disk .2. An approximation of the thin transition layer

In this part of the present work, a simplified model—the thin transition layer theory is proposed. The comparison of this model with the G-L sheet model is made.

Dependência de trajetória nos incentivos fiscais: fragmentação do empresariado na reforma tributária

Desde a promulgação da Constituição de 1988, todos os governos têm buscado realizar a reforma tributária. Há aparente consenso de que essa reforma precisa ser feita. No entanto, os insucessos nas propostas submetidas ao Congresso Nacional têm sido recorrentes. Essa dissertação busca explicar esse aparente insucesso a partir da análise evolutiva histórica de cinco tipos de incentivo fiscal: 1) regional (Sudam, Sudene e Zona Franca de Manaus); 2) guerra fiscal do ICMS; 3) exportação; 4) tributação simplificada (em especial o Simples); e 5) desenvolvimento econômico. O argumento central da pesquisa é o de que a política tributária desenvolvimentista e extrativa, adotada historicamente pelo Estado brasileiro e pautada pela concessão de incentivos fiscais, envolve interesses difíceis de serem revertidos - com características de dependência de trajetória -, que têm condicionado o comportamento do ator fundamental para o desenlace da reforma tributária - o empresariado -, o qual tem atuado de forma fragmentada e na busca por rendas, em vez de atuar de forma concertada buscando o objetivo coletivo pressuposto em uma reforma tributária. A pesquisa evidenciou ter havido uma dinâmica e relevante evolução do sistema tributário no período recente, vinculada em grande medida ao conjunto de incentivos fiscais que foram objeto de análise, o que afasta a hipótese de eventual paralisia decisória e relativizam as hipóteses de pontos de veto e de impasse entre interesses federativos como variáveis explicativas para o insucesso da reforma tributária.