Modelling of a Stirling engine with parabolic dish for thermal to electric conversion of solar energy

Stirling engines with parabolic dish for thermal to electric conversion of solar energy is one of the most promising solutions of renewable energy technologies in order to reduce the dependency from fossil fuels in electricity generation. This paper addresses the modelling and simulation of a solar powered Stirling engine system with parabolic dish and electric generator aiming to determine its energy production and efficiency. The model includes the solar radiation concentration system, the heat transfer in the ther- mal receiver, the thermal cycle and the mechanical and electric energy conversion. The thermodynamic and energy transfer processes in the engine are modelled in detail, including all the main processes occur- ring in the compression, expansion and regenerator spaces. Starting from a particular configuration, an optimization of the concentration factor is also carried out and the results for both the transient and steady state regimes are presented. It was found that using a directly illuminated thermal receiver with- out cavity the engine efficiency is close to 23.8% corresponding to a global efficiency of 10.4%. The com- ponents to be optimized are identified in order to increase the global efficiency of the system and the trade-off between system complexity and efficiency is discussed.

Improving magnetic coupling for battery charging through 3D magnetic flux

The spatial distribution of the magnetic field and the coupling between the coils in the Wireless Power Transfer (WPT) systems is an important aspect to consider in the system design and efficiency optimization. The presented study in this paper is based on tests performed on a physical model. The transmitting (primary) equipment, is an electrical three-phase system, capable to be connected in star or delta (both electrically and geometrically). The measured results allow to describe graphically the magnetic field distribution in three dimensions. The analytical formulas aim to help to understand and to quantify the physical phenomena but they cannot be considered a universal approach and the measurement results help to understand better the observable facts. In the WPT, the key issues that will influence the efficiency, are the alignment of the coils, the spatial orientation of the magnetic field, the detachment and the tilt between the windings, all they changing the magnetic coupling between the transmitter and the receiver of energy. This research is directed not only to the magnetic field distribution but finally, to optimize the energy transfer efficiency.

An Evaluative Model to Assess the Organizational Efficiency in Training Corporations

In an organisation any optimization process of its issues faces increasing challenges and requires new approaches to the organizational phenomenon. Indeed, in this work it is addressed the problematic of efficiency dynamics through intangible variables that may support a different view of the corporations. It focuses on the challenges that information management and the incorporation of context brings to competitiveness. Thus, in this work it is presented the analysis and development of an intelligent decision support system in terms of a formal agenda built on a Logic Programming based methodology to problem solving, complemented with an attitude to computing grounded on Artificial Neural Networks. The proposed model is in itself fairly precise, with an overall accuracy, sensitivity and specificity with values higher than 90 %. The proposed solution is indeed unique, catering for the explicit treatment of incomplete, unknown, or even self-contradictory information, either in a quantitative or qualitative arrangement.