1,721,108 research outputs found
Progress in electrothermal life modeling of electrical insulation during the last decades
No full textThis paper has the purpose of highlighting the achievements during the last decades in life modeling under electrothermal stress. Phenomenological and physical models are examined, considering also a statistical approach, with applications to experimental results
Co-Creating History: The Case of WORTHY as a Virtual Collaborative Museum
No full textValue co-creation unfolds as a system of interactions in which the user and service provider play an active role in collaboratively creating values that go beyond economical and financial worth. Value co-creation is a growing trend in museums; however, little is known about how it can enhance educational activities, especially concerning digital technologies. This study analyzes the role of digital technology in the value co-creation process by addressing the following research questions: (1) how can museums, and schools implement actions to enhance co-creation activities? and (2) how does digital technology contribute to the generation of a value co-creation approach, engaging a young target audience in history education? The research adopts a single case study methodology, which is based on WORld Wars Toward Heritage for Youth (WORTHY), an educational European project that involves cultural and educational institutions from Germany, Poland, Croatia, England, and Italy. WORTHY creates a virtual collaborative museum through a digital platform. The paper's findings make dear that digital technologies play a role in value co-creation through two main experiences: learning and sharing. In the learning experience, digital co-creation is grounded in artifacts and contents, while during the sharing experience, digital technologies play a role relatively to people and content
Study of the synergistic effect of electrical and thermal stresses on insulation life
No full textThe synergism between stresses affects significantly insulating materials or systems subjected to multi-stress conditions, resulting in a reduction of life which can be particularly remarkable when stresses have comparable effects. A factor is defined here, able to quantify the synergism; in the case of two stresses, this factor has a maximum for large values of both stresses and tends to unity (the minimum value corresponding to absence of synergism) when one stress prevails. This behavior has been supported by calculations performed for PolyPropylene capacitors and EPR insulated cable models
Critical examination of the life models for electrical insulation under combined stresses in the light of the boundary conditions
No full textThe combined life models for insulating materials and the boundary conditions that must be satisfied for their mathematical correctness are examined. In the case of materials with threshold, these considerations lead to the introduction of a lower limit gradient of electrical aging, Eo, the existence of which is widely acceptable from a physical point of view. In considering models for materials with threshold, the existence of a thermal threshold, which allows a new general definition of such materials to be forward, is pointed out. Models for materials with threshold in which the limit gradient Eo has been introduced are examined and their mathematical correctness verified. The existence of a threshold curve, and thus of infinite electrothermal threshold couples, is emphasized
Test procedures and lifetime data analysis for electro-thermal endurance characterisation of EPR-insulated cables
No full textThe endurance of EPR-insulated cables is investigated by means of laboratory tests on cable models aged by thermal and electrical stresses, single or combined. The electrical, thermal and multi-stress life lines obtained by tests carried out according to a factorial procedure are reported. A significant contribution to plot the life lines is provided by the combined analysis method, which allows the electro-thermal life surface to be drawn. Indices for electrical, thermal and combined-stress endurance characterisation can thereby be supplied. The test results give high values of electrical, thermal and multi-stress endurance coefficients for the tested cables. This confirms the good electrical and thermal behaviour of EPR-insulated cables. Finally, a comparison of the results with a life model, able to provide life estimations, is made, obtaining good data fitting. © IEE, 1998
Multistress endurance characterization of EPR cable models
No full textThe results of life tests performed on EPR cable models aged by combined thermal-electrical stresses are reported, showing electrical and thermal life lines, intersections of the life surface with the planes at constant stress. The Combined Analysis Method (CAM) is used to obtain more information on the behavior of the tested cable in a wide voltage and temperature range. Parameters useful for insulation characterization and cable design are derived
Life models for insulating materials in combined-stress conditions
No full textIn the paper, single-stress electrical and thermal models for life prediction of electrical insulating materials are presented, as a basis for the derivation of combined-stress models, both for threshold and non threshold materials. A critical analysis of these models allows the definition of the concept of threshold and non-threshold material behaviour, as well as the attainment of a new general combined-stress model, valid for all materials, irrespective of the existence of a threshold at room temperature
Insulation characterization in multistress conditions by accelerated life tests: An application to XLPE and EPR for high voltage cables
No full textThe procedures for testing electrical insulating materials in order to obtain information on their ability to withstand stresses are still the subject of lively debates
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
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