Search results for "33"

Study of Influence of the LED Technologies on Visual and Subjective/Individual Aspects

2018

The general aim of this paper is that to further deepen and elaborate the results obtained in a previous study of the authors, in which the relationship between the characteristics of five different types of LED lamps and the humans non-image-forming reactions were investigated, by conducting a more detailed statistical analysis and by highlighting the neurological aspects.

Does the 5-strand-graft have superior biomechanical behaviour than 4-strand-graft during acl reconstruction?

2019

Purpose. This study aimed to compare the biomechanical proprieties of 4 and 5-strand- grafts. Methods. For the present study, fresh-frozen bovine common digital extensor tendons were used. Tendon grafts were prepared and sized to have a length of almost 27 cm and a cylinder 4 strand diameter of 8 mm. In half of all samples (Group A, n=12,), the graft was formed by 2 bundles duplicated around a metallic rod creating a 4-strand-tendon construct. In the other half of samples (Group B, n= 12,) 5-strand-tendon construct was created duplicating a single tendon around the rod, and tripling the other one. The grafts were preconditioned at 50 N for 10 min, followed by 1,000 cyclic loading between 50…

A methodology for assessing the impact of salinity gradient power generation in urban contexts

2018

Abstract The paper proposes a methodology to assess the potential impact of salinity gradient power technology in urban contexts. The idea to employ such energy source in urban contexts derives from the observation that, among the energy districts outputs, low-salinity treated wastewater can be used to produce electricity if a suitable source of high salinity feed (seawater of a salt-works) is also available. The methodology uses the HOMER software for assessing the district’s electric energy production, consumption and exchange with the main grid. Then, starting from the total gross surface and the number of inhabitants of the district, some possible realistic scenarios characterized by di…

Modeling, Simulation and Experimental Verification of a Static Series Compensator (SSC) for Voltage Sag Mitigation

2004

Short-circuit Calculations in Hybrid AC/DC Microgrids

2022

In this paper, the issues related to short-circuit calculations in hybrid AC/DC microgrids are discussed. The reference standard for short-current calculations in DC systems is the IEC 61660, which provides a mathematical formulation of the problem. The standard only includes radial DC grids and does not consider a more complex system, such as meshed DC systems or a hybrid AC/DC microgrid. This paper proposes a generalized approach that can be used independently of the characteristics of the hybrid system. The proposed approach is applied to two test microgrids and the results are compared with those obtained simulating the same grids with Neplan 360.

Dynamic Control of Static Converters for the Transition from Grid-on to Grid-off Operation of AC/DC Microgrids

2022

In this paper, specific control logics defined for generators, controllable loads and electric energy storage systems are illustrated in order to improve the reliability of AC/DC hybrid microgrids in their grid-off operation following failure events such as short-circuits, line breaks, sudden disconnections of generating units or loads, etc. After defining specific control schemes, these were modelled in a digital environment and finally tested with dynamic simulations. Finally, the paper highlights the role of virtual synchronous machine control for the self-healing capacity of islanded hybrid microgrids.

FROM FUEL BASED GENERATION TO SMART RENEWABLE GENERATION: PRELIMINARY DESIGN FOR AN ISLANDED SYSTEM. PART I: TECHNICAL ISSUES AND FUTURE SCENARIOS

2011

The subject addressed in this paper is the analytical study of the transition of the energy generation system for a real MV/LV distribution system from a ‘fuel based’ one to a distributed and smart ‘renewables based’ one. The paper outlines the technical issues related to such transition from one type of system to the other. The study is carried out for a real islanded MV/LV distribution network located in the Island of Pantelleria. The economical issues regarding the above transition are focused in a companion paper.

DEMAND Project: A Proposal for a Bottom-Up Aggregation Platform

2019

In many countries, a great number of electricity market operators have developed Demand Response (DR) programs with different purposes. In this framework, load aggregation represents an important issue, linked to the potential that the coordinated management of distributed resources has on affecting power systems' operation.

Strategie e scenari di aggregazione delle risorse distribuite nel mercato elettrico

2016

L’articolo espone una modalità per ampliare la base di partecipazione di soggetti connessi alla rete elettrica (aggregatori di carico, sistemi di accumulo distribuiti, ecc.) ai mercati dei servizi già regolamentati, sfruttando opportune azioni di controllo di tipo Demand Response.

A decoupled method for solving distribution networks with PV nodes

2009

In this paper, a methodology for the load flow solution of distribution systems with fixed voltage nodes (PV nodes) is presented. The proposed technique is the extension of a methodology already set up by the authors to solve distribution systems; it is an iterative approach devoted to the treatment of voltage dependent loads; at each iteration, all the network components (lines, loads, and PV nodes) are represented by resistances and reactances. The methodology is based on the identification of two networks that are solved in sequence, thus allowing the attainment of state features of the original system. One of the two systems is made up only of shunt and series resistances; the other onl…