https://www.um.edu.mt/library/oar/handle/123456789/1441 2026-04-04T23:55:33Z https://www.um.edu.mt/library/oar/handle/123456789/23458 Title: Development of a hollow concrete block with improved thermal properties, having same dimensions and load bearing characteristics as the traditional HCB (THERMHCB) Abstract: Presentation given by Ing. Yousif on the development of a hollow concrete block with improved thermal properties, having same dimensions and load bearing characteristics as the traditional HCB (THERMHCB). This presentation was given as part of an overview of the externally funded research projects being carried out at the ISE. 2013-01-01T00:00:00Z https://www.um.edu.mt/library/oar/handle/123456789/23442 Title: Assessing the offshore wave energy potential for the Maltese islands Authors: Drago, Aldo; Azzopardi, Joel; Gauci, Adam; Tarasova, R.; Bruschi, Antonello Abstract: Direct wave observations using a Datawell buoy deployed to the west of Gozo, and a numerical wave modeling exercise targeted to map the spatial and temporal signatures of the wave fields around the Maltese Islands over a span of five years (1st January 2007 to 31st December 2011) have been conducted within the BLUE OCEAN ENERGY® project. This has provided a detailed characterization of local wave climates and an estimation of the available wave energy potentials in the coastal and offshore areas of the Maltese Islands. This data is essential to assess the overall feasibility of constructing wave energy production farms based on WECs, to test the most adequate devices to harvest wave energy, as well as to identify the best candidate sites for an optimal and most economically practical extraction. The study reveals that the best sites in the Maltese waters would be those located at the western approaches to the islands, given that these are more exposed to the prevailing North-Westerly winds. At these sites, maximum significant wave heights can exceed 7 m in winter, even in close proximity to the coast, and with a seasonal mean of 1.92 m as determined from direct measurements. The mean wave power transport during the winter season is estimated at 15 kW m-1; the wave resource is more than halved in spring and even weaker in autumn; it is under 2 kW m-1 during summer. Stronger wave fields occur at a few kilometres to the South West of Filfla Island where the modelled mean wave power reaches values of 13 kW m-1 in the winter months, but at less accessible sites and greater distances from shore. 2013-01-01T00:00:00Z https://www.um.edu.mt/library/oar/handle/123456789/23436 Title: Use of photovoltaic energy storage systems in buildings and other applications Authors: Agosta, Antonino Fabio Abstract: This paper illustrates the use of storage systems with stand-alone photovoltaic systems to be used in buildings of Malta for integration of electricity and energy saving and special applications in other areas. The present energy situation suggests that the future of the domestic and industrial photovoltaic systems will include storage systems, to improve resource management of feeding renewable energy into the national grid, and increase reliability at the generation site. The paper develops around the initial stages of photovoltaic integration into the grid, when the possibility of auto consumption or net-metering was used. However, increased penetration of photovoltaic systems could now reduce the existing network load, while still not solving the main limitation of renewable sources, which is the intermittent nature of the production. Especially photovoltaics, but not only, the limitations of PV electrical generation is also subject to a certain cyclical production be it daily or seasonal, and a certain amount of “unpredictability of production”. Such issues have a solution through energy storage. The production of electricity for other special applications would include on-site production of energy for stand-alone systems. 2013-01-01T00:00:00Z https://www.um.edu.mt/library/oar/handle/123456789/23432 Title: Control of a doubly fed induction machine in a wind energy conversion system Authors: Scicluna, Kris; Spiteri Staines, Cyril; Apap, Maurice Abstract: This paper presents research done on the closed-loop control of the Doubly Fed Induction Machine (DFIM) applied to a Wind Energy Conversion System (WECS). Basic generator configurations used in wind energy systems, mainly fixed-speed and adjustable speed generators are discussed. A suitable Stator Flux Oriented (SFO) control topology for the DFIM is shown with which it is possible to control the stator active and reactive power. The control system designed was implemented on an experimental rig which emulates the behaviour of a practical WECS. A brief overview of sensorless algorithms is also presented; these algorithms are used to provide rotor speed/position estimates in the absence of a speed sensor. Practical results in both sensored and sensorless operation are shown including measurements for rotor currents, stator active/reactive power and rotor speed/position estimates. 2013-01-01T00:00:00Z