A questão russa: seu lugar nas reflexões de Vanguarda Socialista

Vanguarda Socialista, jornal editado por Mário Pedrosa no Rio de Janeiro, de 1945 a 1948, elabora uma proposta política socialista e democrática como alternativa à concepção bolchevique, que acredita superada pela história. Nessa medida, a questão russa encontra-se no centro das preocupações do grupo. Este artigo procura não só analisar a explicação do jornal para as origens da burocracia na URSS, mostrando as contradições que a perpassam, como também estabelecer a filiação do grupo às idéias de Rosa Luxemburgo, na tentativa de esclarecer as referidas contradições.

Permanent Magnet Hall Thruster for satellite orbit raising with low power energy consumption

Electric propulsion is now a succeful method for primary propulsion of deep space long duration missions and for geosyncronous satellite attitude control. Closed Drift Thruster, so called Hall Thruster or SPT (Stationary Plasma Thruster), was primarily conceived in USSR (the ancient Soviet Union) and, since then, it has been developed by space agencies, space research institutes and industries in several countries such as France, USA, Israel, Russian Federation and Brazil. In this work we present the main features of the Permanent Magnet Hall Thruster (PMHT) developed at the Plasma Laboratory of the University of Brasilia. The idea of using an array of permanent magnets, instead of an electromagnet, to produce a radial magnetic field inside the plasma channel of the thruster is very significant. It allows the development of a Hall Thruster with power consumption low enough to be used in small and medium size satellites. Description of a new vacuum chamber used to test the second prototype of the PMHT (PHALL II) will be given. PHALL II has an aluminum plasma chamber and is smaller with 15 cm diameter and will contain rare earth magnets. We will show plasma density and temperature space profiles inside and outside the thruster channel. Ion temperature measurements based on Doppler broadening of spectral lines and ion energy measurements are also shown. Based on the measured plasma parameters we constructed an aptitude figure of the PMHT. It contains the specific impulse, total thrust, propellant flow rate and power consumption necessary for orbit raising of satellites. Based on previous studies of geosyncronous satellite orbit positioning we perform numerical simulations of satellite orbit raising from an altitude of 700 km to 36000 km using a PMHT operating in the 100 mN - 500 mN thrust range. In order to perform these calculations integration techniques were used. The main simulation paraters were orbit raising time, fuel mass, total satellite mass, thrust and exaust velocity. We conclude comparing our results with results obtainned with known space missions performed with Hall Thrusters. © 2008 by the American Institute of Aeronautics and Astronautics, Inc.

A crise orgânica do Partido Comunista Brasileiro (PCB) e o declínio do socialismo real

Pós-graduação em Ciências Sociais - FFC

Sanções econômicas internacionais

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)