ABSTRACT: This paper exposes initially the motivations for developing a TRL online calculator by AEB (Brazilian Space Agency; in Portuguese, Agência Espacial Brasileira). Such motivations demand the tool to be a way not only to assess the TRL condition of operational space missions and systems, but also as a method of evaluating and sharing proposals with new technological content. The TRL methodology and its relation to risk management are discussed. The development phases of the IMATEC Lite application are then described, with emphasis to the data handling structure capable of storing the user product model. A result of technology assessment using the software is detailed by presenting the PBS of the SERPENS 1 mission nanosatellite. The prospects of using the tool for judging the acceptability of new missions and projects are discussed, as well as some of the encountered difficulties.

Abstract In this work, the mechanism behind motion in closed systems is investigated by studying two simple mechanical systems. Firstly, a simple “ballistic” car system introduces the subject of propulsion as a function of a parameter that modulates the amount of ejected mass, thus allowing a transition between a closed to an open system. The second example provides a physically realizable (and optimizable) system, in which a mass sliding on the internal surface of a mechanical wheeled cavity is shown to produce a net movement, provided that dissipation is present. Several additional ways are discussed by which to ‘open’ a system whilst keeping the mass constant. As a function of strict momentum conservation, it is concluded that both internal mass motion and dissipation are key factors in the only way a mechanical system can move itself in a weak sense, in contrast to a strong meaning of ‘self-propulsion’.

Sabe-se que o pico de radiação de corpo negro depende da descrição adotada, a saber, se em frequência ou em comprimento de onda. Este artigo traz uma exposição pedagógica sobre como escrever e estimar o espectro da distribuição de Planck em duas escalas espectrográficas distintas. Mostramos que a potência emitida do máximo de corpo negro é única e não coincide com o pico medido, seja em frequência ou comprimento de onda. Então, fazemos uma generalização com outras funções de distribuição com o objetivo de clarificar ainda mais a questão.

It is well known that the peak of black body radiation depends on the adopted description, whether as a function of frequency or wavelength. This paper is a pedagogical exposition of how to write and estimate Planck's distribution spectrum on two distinct spectrograph scales. We show that the emitted power of the Black Body maximum is unique and does not coincide with the peak measured whether in frequency or wavelength. We then make a generalization with other distribution functions in order to further clarify the apparent issue.

Nesse trabalho apresenta-se um estudo de soluções numéricas para o problema de capacitores cilíndricos finitos em eletrostática, a partir da integração da equação de Poisson utilizando um esquema de diferenças finitas. Soluções são obtidas pelo método da relaxação sucessiva. O problema ilustra o tratamento numérico na obtenção de soluções eletrostáticas em problemas diferentes dos encontrados em livros-texto. Para o problema em questão, diversas quantidades de interesse (distribuição de cargas, capacitância, energia do campo eletrostático, força) podem ser comparadas com o caso analítico infinito.

In this work we present a study of numerical solutions for finite cylindrical capacitors based on the integration of Poisson equation using a finite difference scheme. Solutions are obtained by successive over relaxation (SOR). The problem illustrates the numerical treatment involved in the solution of problems not found in textbooks. Several interesting quantities (charge distribution, capacitance, electric field energy, force) may be compared to analytical results for the infinite capacitor.

A semiclassical formula for the coherent-state propagator requires the determination of specific classical paths inhabiting a complex phase-space and governed by a Hamiltonian flux. Such trajectories are constrained to special boundary conditions which render their determination difficult by common methods. In this paper we present a new method based on Runge-Kutta integrator for a quick, easy and accurate determination of these trajectories. Using nonlinear one dimensional systems we show that the semiclassical formula is highly accurate as compared to its exact counterpart. Further, we clarify how the phase of the semiclassical approximation is correctly retrieved during the time evolution.