1,721,087 research outputs found
Shielding effectiveness for a three-phase transformer at various harmonic frequencies
No full textA two-step optimisation procedure for the design of a passive shield aimed at decreasing the low-frequency magnetic field using a transformer is presented. After having introduced the relevant characteristics of the medium size three-phase transformer, the procedure is described in detail. It is based on the decomposition in the harmonic component of the radiated field, which is associated with the direct, inverse and homopolar sequences of the current of the transformer. The effect of the optimised shield is verified by measurements
Contribution of Wayside Energy Storage Systems to Short Circuit Currents in DC Railway Traction Power Systems
No full textAs a consequence of the growing demand for mobility and the requirements for reduced environmental pollution, railway traction systems are receiving increasing interest. Researches are analyzing new technologies and managing solutions to increase energy efficiency in the railway infrastructures. Many studies proposed the oppor-tunity to introduce the technology of energy storage systems (e.g., Wayside Energy Storage Systems - WESS) in traction infrastructures. WESS can be able to: i) reduce voltage drops; ii) save braking energy; iii) support Traction Power Substations in supplying traction power peaks. A relevant topic in using WESSs in railway infrastructure is to verify their impact in case of faults. Studies on short circuit analyses are required to verify the correct rating of the protection devices and the opportunity to use new protection devices and mode of operating, when the new technology is integrated. In this paper, the typical Italian DC railway power system is investigated. Specifically, the contribution of WESS to the short circuit currents is assessed by examining transient and steady-state conditions
Osservazioni preliminari sulla valutazione dei fattori di rischio psicopatologico in un campione di pazienti ustionati
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Planning the Integrated Management of Organic Waste Flows and Agricultural Residues for a Circular Economy
Full text linkIn the recent years, the production, management and disposal of both organic waste and agricultural residues has become significantly difficult in Italy, due to the lack of suitable facilities. Very often, indeed, within the different regions, there are no treatment plants for the organic fraction of municipal solid waste or agricultural residues treatment centres, so as to give them a second life in the perspective of a circular economy. The lack of proximity treatment centres, forces local administrations to send these flows to plants outside their territorial area, with a consequent
increase for transport and treatment costs. This paper, with reference to the study area of the Matera municipality (Basilicata region - Southern Italy), taking into consideration the organic waste flows of non-domestic users from separate collection and agricultural residues - especially those coming from the wine production chain - provides a state-of-the-art analysis of the problems related to their collection, management and disposal. Subsequently, an alternative model feasibility study - called "proximity composting", aimed at a more sustainable management of these flows based on their “zero-kilometers treatment” – has been implemented. The results obtained have demonstrated that the proposed scenario is much more sustainable when compared to the
current situation, both from an economic and environmental point of view. Indeed, thanks to the use of calculation tools, the economic (€/year) and environmental (Kg CO2 avoided/year) advantages, due to the save of transport and disposal of flows outside the region, have been quantified, with consequent reduction of waste tax for citizens (€/year). In addition, the implementation of maps using a Geographical Information System (GIS) has demonstrated a better optimization of the system. Finally, it was highlighted the social utility of the proposed model, because citizens become an active part in the process and self-produce soil fertilisers
Integration of Onboard Batteries and Supercapacitors Based on the Multi-Source Inverter for Light Rail Vehicles
No full textLight rail vehicles with onboard energy storage systems have gained increasing interest due to higher efficiency and lower or null local emissions in catenary-less operation. Their traction circuit conventionally employs inverters to drive the traction motors and DC/DC converters to manage the onboard sources. Recently, the concept of multi-source inverter (MSI) was introduced for single-stage integration of AC loads and multiple DC sources without. This paper evaluates the feasibility and attractiveness of the MSI for single-stage integration of batteries and supercapacitors to the traction motors in a catenary-less tramway vehicle. The configuration of the MSI-based hybrid energy storage system is detailed. Numerical simulations are carried out to assess its performance over a typical driving cycle. Furthermore, the proposed architecture is compared to a standard configuration employing a DC/DC converter to control the supercapacitors, with focus on power losses and volumes of the converters and DC sources
Comparing Full Lateral Metallization and Reference Plane Stitching in LTCC Boards for Satellite Applications
No full textIn this paper a methodology for taking into account the frequency dependence of a possible referencing (grounding) techniques in LTCC boards for satellite applications is presented. The aim of this work is to analyze and compare the input impedance and S-parameters values for different strategies of inter connection of the reference planes among them. The numerical analysis presented has proven the importance of the lateral metallization set up in the LTCC board working into a metal housing. For board used stand alone the lateral metallization can be replaced by an adequate density of vias stitching among the planes. The modelling agrees well with real grounding solution
Assessment of Seismic Retrofitting Interventions of a Masonry Palace Using Operational Modal Analysis
No full textThe paper delivers a short report about the modal identification carried out on a historical masonry palace in the city centre of L’Aquila, Palazzo Pica Alfieri, retrofitted after the 2009 earthquake. A concise description of the damage pattern and the retrofitting interventions heads the presentation of the results of the dynamic identification using Operational Modal Analysis. The identified mode shapes and natural frequencies drive a discussion about the detectability and the assessment of the modifications induced by the structural interventions using low-vibration measurements. Differently from more uncomplicated structures, the production of a Finite Element model representative of an existing masonry complex requires considerable efforts: the masonry structure may not behave like a continuum, due to the presence of cracks and unknown structural discontinuities. Still, the results of the dynamic identification bestow valuable information about the structural behaviour from a qualitative viewpoint, even if not backed by a faithful FE model. The paper addresses the aspects possibly related to the dynamic identification of a monumental masonry building, based on the shreds of evidence arisen from the presented case study
Aspetti psicodinamici e prospettive d’intervento terapeutico nei pazienti con trauma da ustione
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