Search results for "forme"
showing 10 items of 1192 documents
Medium Voltage Smart Grid: Experimental Analysis of Secondary Substation Narrow Band Power Line Communication
2013
This paper is focused on the possibility of employing narrow band power line communication (PLC) in medium voltage (MV) distribution networks. The topic is investigated by means of both simulations and experimental tests, which were carried out in the distribution network of Ustica Island. In detail, a two-way MV communication was tested between two secondary substations connected by an MV cable power line. Each substation has a by-pass connection at MV bus-bars and an MV/LV oil filled power transformer. In this paper, the MV and the PLC systems under test are described and the experimental tests are presented, which were carried out to evaluate the parameters of the simulation model. The a…
Parameterizing non-linear magnetic cores for PSpice Simulation
2005
Abstract. In this paper the main Jiles & Atherton parameters of a magnetic material, according to their particular working condition (mainly frequency, temperature and waveform) are calculated by means of a systematic procedure that use PSpice and MathCad. The modelled magnetic material is used for power electronics circuit simulation, which uses magnetic materials, working at frequencies in the region of kH, to construct transformers and inductors. Magnetic materials are the most critical components in electronics simulators due to their nonlinear behaviour and the accuracy in the simulation can only be obtained through a proper magnetic material modelling. This paper examines the modellin…
Obtaining the electrical model of a power transformer by means of finite element software
2005
Abstract. The behaviour of transformers and inductors working at high-frequencies and high power density can dramatically differ from the ideal or low-frequency operation. Their performance is very dependent on the magnetic material, operating frequency and physical construction. In this paper, finite element analysis (FEA) is used to obtain an accurate characterization of the electromagnetic behaviour of these magnetic components.
A back to back method for the temperature rise test of prefabricated substations: A case study
2015
In this work a back to back method is presented which allows to develop heating tests of prefabricated secondary substations with a limited number of supplying equipment (an induction regulator and a capacitor bank). The proposed method makes use of the transformer tap changers to create a voltage difference on the medium voltage side. In this way, only an adjunctive low voltage supply is needed. With the proposed test system, the heating tests are developed on a 1000 kVA prefabricated substation. Thanks to the experimental tests, the class of enclosure of the substation and the operating temperature and resistance of the power transformers are determined, according to the recommendations o…
Informal language in English L2 writing: What are pupils taught from textbooks?
2019
AbstractStudies show that intermediate and advanced learners of English overuse informal features in their academic writing, and researchers recommend that instructional material is developed to raise learners’ awareness of this overuse. In Norway, little research has been done on younger learners’ writing, and no previous study exists of how instructional material such as textbooks deal with informality. The present article investigates how all English textbooks published for lower secondary school under the current curriculum deal with informality in writing. The findings show that eight out of nine textbooks include instruction on informality. The most frequently mentioned informal featu…
L’université au risque du changement
2018
National audience
Du collège d'enseignement technique au lycée professionnel : une intégration progressive dans le second cycle
1996
From technical schooling to vocational high school : gradual integration in the second cycle. The vocational high school integration in the second cycle was carried out within the scope of administration, sometimes antagonistic, of firstly social functions then economic, successively favoured in training centres. From the 1980's onwards, basic changes in the conception of workers' training were brought about by reforms. This resulted in important changes in orientation, administration in academic establishments, where innovating teaching practices coexist with lasting sociological sluggishness.
Sub specie æternitatis: the role of the ruin and the ancient in the process of architectural renewal between metamorphosis and resurgence
2022
Composing new works of architecture inspired by vestiges from antiquity or archaeology. The reflections and the case study which will be proposed, pertaining to a recent design experiment for the archaeological area and Antiquarium of Tyndaris, are dedicated to this theme. Over and above any charm exerted by such places, by landscapes in which the ruins appear identical in substance and which sometimes manifest themselves as “sub specie æternitatis”, there are reasons linked to the very profession of architect and to the gashes in the crucible of controversies around the role of history in its contentious relationship with architectural design. That apart, the aporias revealed by Michel Fou…
Medium-term dynamics of element concentrations in a sparid fish and its isopod parasite after the Prestige oil-spill: Shifting baselines?
2019
Historically, the European Atlantic is probably the most important oil-spill hotspot worldwide. One of the most recent accidents occurred in 2002 when the oil-tanker Prestige sank over the Galician Bank causing two major oil-spills followed by several small leaks until March 2003. This resulted in contamination of virtually all types of marine habitat. Considering that parasites have proved to be good effect and accumulation bioindicators, the present study addresses the medium-term changes in trace element content after the Prestige oil-spill in a model host-parasite system, the bogue, Boops boops (Sparidae) and the isopod Ceratothoa oestroides. To our knowledge, this study is the first to…
Behavioural responses of breeding arctic sandpipers to ground-surface temperature and primary productivity
2021
Most birds incubate their eggs, which requires time and energy at the expense of other activities. Birds generally have two incubation strategies: biparental where both mates cooperate in incubating eggs, and uniparental where a single parent incubates. In harsh and unpredictable environments, incubation is challenging due to high energetic demands and variable resource availability. We studied the relationships between the incubation behaviour of sandpipers (genus Calidris) and two environmental variables: temperature and a proxy of primary productivity (i.e. NDVI). We investigated how these relationships vary between incubation strategies and across species among strategies. We also stud…