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This paper presents the physical design and experiments of the Concentrating Transpired Air Heating (CTAH) system as a combination of subsystems of parabolic primary and circular secondary reflector that concentrates incident solar radiation onto an inverted perforated absorber. Optical efficiency of the CTAH system has been analysed using a 2D ray tracing model. Experiments have been carried out for 50% perforated black painted aluminium inverted absorber for glazed and unglazed systems. Results show a significant temperature rise of the absorber surface in both cases. The maximum temperature of the absorber for the unglazed system is 52.1°C at 22.5°C ambient temperature, where as for the covered system, it is 67.9°C at 23.2°C ambient temperature.

Recently, the satellite research is more focused First of all the physical structure and construction of the towards the development of micro and nano satellites. The reason HTS momentum wheel has been described then the behind this is that the development and launching of micro and mathematical modeling procedure is summarized and the nano satellites have less risk and less cost involved. This paper is motion equations have been presented. In the end there are about the attitude control of micro/nano satellites which are simulation results and concluding remarks. relatively smaller in size and weight if compared to the conventional satellites. The barriers, for the attitude control of II. LEVITATION AND HIGH TEMPERATURE these satellites, are the less mass and the less power budget. SUPERCONDUCTORS Hence, the normal attitude sensors and actuators cannot be used.In order to have a good understanding of mathematical The attitude control system of the micro and nano satellites relies model developed in the later section some terms are briefly on a novel technology known as Micro Electro-Mechanical described in this section [4]. Systems (MEMS) technology. In this paper, use of high A. Levitation temperature superconductor (HTS) magnet momentum wheel hasLevitation is a phenomenon in which an object occupies a been proposed for the attitude control system of micro and nano fixed position in a gravitational field without the benefit of satellites and the design, working principles and the mathematical support by d arect physgcal contact with other objects and does model of the HTS momentum wheel are elaborated. In the end the so b ct physica conttits. mathematical model of the HTS momentum wheel has been notnecessarly nvolve magnetism. analyzed on the basis of simulation results. It can be of two types. a Active Levitation: In active levitation an external feedback controller is needed to have a stable I. INTRODUCTIONleiaon

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