Net electric power of concentrating solar mirror systems for application in space as a function of the distance to the sun

The use of solar radiation by means of concentrating solar mirror systems, such as parabolic and spheric configurations, mainly is an engineering problem. A decisive characteristic for the optimisation of a complete system with turboelectric power conversion is the thermal cycle applied. Besides the Carnot process, here taken up into the study as an ideal comparative process, suitable processes for the technological realisation are the Brayton process and the Rankine process. The Brayton process is a typical gas turbine process using only the gaseous phase. The Rankine process is a steam engine process using liquid and gaseous phase.The work in hand shows how such solar systems with turboelectric conversion are optimised with respect to their specific weight (kg/kW_e) and how the distance to the sun as well as technological data enter into the analysis.As expected, the Carnot cycle as an ideal comparative process for both types of systems shows the best results for the optimum specific mass of the system. Regarding the real processes, the Rankine cycle shows more favourable characteristics than the Brayton cycle. The difference of the specific masses of the real processes mainly results from the different thermal conditions at the radiator.The influence of the distance to the sun is as expected. The nearer to the sun the solar power system operates, the better is the optimum specific mass of the system. For distances to the sun between 0.3 and 1.0 AU the spheric system shows a better behaviour than the parabolic system. For distances to the sun greater than 2.0 AU the parabolic system shows better behaviour of the specific weight. In the region between 1 and 2 AU the better optimum specific mass of the system belongs to the technological data used in the analysis.     

Hazard Prevention in Mission Plans for Aerial Vehicles Based on Soft Institutions

Hazard prevention in mission plans requires careful analysis and appropriate tools to support the design of preventive and/or corrective measures. It is most challenging in systems with large sets of states and complex state relations. In the case of sociotechnical systems, hazard prevention becomes even more dicult given that the behaviour of human centric components can at best be partially predictable. In the present article we focus on a specic class of sociotechnical systems namely air spaces containing pilot controlled as well as autonomous aircrafts and introduce the notion of relevant hazards. We also introduce soft institutions as an appropriate basis for analysis, with the aim of addressing relevant hazards. The concept of soft institutions is drawn from specication languages for interaction between agents in multi agent systems but, in our case, is adapted for use in systems that combine human and automated actors.