2,728 research outputs found
Core Loss Estimation in Electric Machines With Flux-Controlled Core Loss Tester
No full textTsukerman, Igor/0000-0001-8318-3225; Tekgun, Burak/0000-0003-2720-8816; Sozer, Yilmaz/0000-0003-3971-3967The complexity of core loss estimation is a serious challenge in the design of high-efficiency electric machines. Current estimation methods based on the Steinmetz equation and loss separation are not accurate enough, even at the rated conditions. This paper describes a loss estimation technique combining finite-element analysis (FEA) and actual core loss measurements. First, flux density waveforms in various parts of the electric machine are determined using FEA. Second, the same waveforms are generated in a wound toroidal core made of the same material as used in the machine. The loss is measured per unit mass, and then the total motor core loss is calculated by integrating the measured W/kg loss values for predefined sections of the motor. These estimation results are compared with those of the Bertotti method. The proposed procedure is shown to improve the accuracy of loss estimation.ABB US Corporate Research; U.S. National Science Foundation [DMS-1620112]This work was supported by fellowships from ABB US Corporate Research. The work of I. Tsukerman was supported in part by the U.S. National Science Foundation under Grant DMS-1620112. (Corresponding author: Yilmaz Sozer.
A priori error indicator in the transformation method for problems with geometric uncertainties
No full textVersion éditeur de cette publication à l'adresse suivante : http://ieeexplore.ieee.org/xpl/articleDetails.jsp?arnumber=6514655To solve stochastic problems with geometric uncertainties, one can transform the original problem in a domain with stochastic boundaries and interfaces to a problem defined in a deterministic domain with uncertainties in the material behavior. The latter problem is then discretized. There exist infinitely many random mappings that lead to identical results in the continuous domain but not in the discretized domain. In this paper, an a priori error indicator is proposed for electromagnetic problems with scalar and vector potential formulations. This leads to criteria for selecting random mappings that reduce the numerical error. In an illustrative numerical example, the proposed a priori error indicator is compared with an a posteriori estimator for both potential formulationsThis work is supported by the program MEDEE funded by the Nord Pas de Calais council and the European Community and supported in part by the National Science Foundation under Grant No. 1216927
Effective constitutive parameters of plasmonic metamaterials: Homogenization by dual field interpolation
No full textWe introduce a general implementation of the recently proposed homogenization theory [Tsukerman, J. Opt. Soc. Am. B 28, 577 (2011)] allowing one to retrieve all 36 linear constitutive parameters of any 3D metamaterial with parallelepipedal unit cells. The effective parameters are defined directly as linear relations between pairs of coarse-grained fields, in contrast with methods where these parameters are obtained from reflection and transmission data or other indirect considerations. The method is applied to plasmonic metamaterials with spherical gold particles and split-ring resonators (SRR), respectively. In both cases, the expected physical behavior is reproduced almost perfectly, with no unphysical artifacts
Modeling of Nanostructured Magnetic Field Sensors
No full textA panoramic view of recent nanostructured magnetic field sensors has been provided, focusing on the modeling of some examples of device concepts, with possible applications in high-tech sectors including automotive, aerospace, Information and Communications Technology (ICT), and medical fields. In particular, this chapter provides a description, from physical basic principles to numerical simulation, of magnetoresistive nanosensors based on anisotropic magnetoresistance (AMR) or planar Hall effect (PHE), novel sensing elements exploiting ferromagnetic resonance (FMR) in nanopatterned magnetic thin films, and miniaturized Hall probes. Specific attention has been devoted to their application in the detection of magnetic nanoparticles or microbeads for biomedical and biochemistry applications, sectors in which very high-sensitivity and submicrometric resolution are required
Homogenization of laminated magnetic cores and the role of surface charges
No full textDue to its theoretical and practical significance, homogenization of laminated magnetic cores has been studied by several research groups. Recently, Tsukerman and Markel proposed non-asymptotic and nonlocal homogenization theories for periodic electromagnetic structures at high frequencies. This paper explores the applicability of these theories to laminated magnetic cores at power frequencies. Particular attention is paid to the boundary condition for the electric current density: its normal component does not have to be zero and may produce surface charges. The eddy current problem inside conducting elements must be coupled with the quasi-static problem outside. The importance of the boundary condition for the current density extends far beyond the simulation of laminated cores - to a variety of eddy current and coupled field-circuit problems
Data and platform co-ops in smart city citizenship: interview with Igor Calzada
No full textIgor Calzada is a senior researcher at universities like Oxford and Cardiff with a focus on urban, regional and technopolitical transformations, considering data issues and social innovation. In November 2020, he launched the book Smart City Citizenship, which proposes another framework at smart cities based on democratic governance and citizenship. Thus, he presents how it is possible to understand and intervene in technopolitical disputes involving algorithms, data, and artificial intelligence based on notions such as digital sovereignty. Among the possibilities, there is the creation of data and platform co-ops based on data and digital commons. For the author, data cooperatives are a subtype of platform cooperatives, in which they focus on business models, while data co-ops share and store data. The book analyzes, among other cases, the Barcelona ecosystem and proposes perspectives for public policies. Currently, Calzada is interested in exploring new models of data governance and artificial intelligence to propose alternative ways to data ecosystems in the European scenario. He defends experimental cities as a reaction to the mainstream idea of the city as a platform, as a reproduction of extractive and panoptic practices through hyperconnectivity. But it will be very difficult in a dangerous context. And he provokes: “how, in the current context, in which we are closed in our homes, can we propose cities with open systems? Other recommendations from the author are an article on platform and data co-ops published in Sustainability journal and a conversation in Spanish about social innovation in smart cities. Read the interview with Igor Calzada: https://digilabour.com.br/2021/01/06/data-and-platform-co-ops-in-smart-city-citizenship-interview-with-igor-calzada
Piano works by Igor Stravinsky
No full textIn my work I thought was right at first a brief outline development work of Igor Stravinsky. I also tried to "map out" the emergence of some major piano works by the author. finally, I added a few notes on the piano interpretive art of Igor Stravinsky
Introduzione a Igor Spanò (a cura di) Il Teatro e la festa. Il tempio, la piazza, la scena
No full textPer tre giorni gli studiosi che sono intervenuti al Convegno hanno riflettuto sul senso e sulle funzioni, sulle pratiche cultuali e rituali, sui luoghi che hanno definito nel corso del tempo i momenti della festa e sulle forme di rappresentazione agonistica (danze, corse, gare, giochi di abilità) o drammatica - di cui erano parte essenziale la musica e il canto - che, spesso intrinsecamente, li accompagnano. L'autore nella sua introduzione esamina le sfumature di significato che racchiude il termine utsava, “festa”, “gioia” in sanscrito.For three days the scholars who spoke at the conference reflected on the meaning and functions, on the cult and ritual practices, on the places that have defined the moments of the celebration over time and on the forms of competitive representation (dances, races, competitions, skill games) or dramatic - of which music and singing were an essential part - which, often intrinsically, accompany them. In his introduction, the author examines the nuances of meaning contained in the term utsava, "feast", "joy" in Sanskrit
DigiTranScope: the governance of digitally-transformed society
No full textThis volume presents the key outcomes and research findings of the Digitranscope research project of the European Commission Joint Research Centre. The project set out to explore during the period 2017-2020 the challenges and opportunities that the digital transformation is posing to the governance of society. We focused our attention on the governance of data as a key aspect to understand and shape the governance of society. Data is a key resource in the digital economy, and control over the way it is generated, collected, aggregated, and value is extracted and distributed in society is crucial. We have explored the increasing awareness about the strategic importance of data and emerging governance models to distribute the value generated more equitably in society. These findings have contributed to the new policy orientation in Europe on technological and data sovereignty and the sharing of data for the public interest. The digital transformation, the rise of artificial intelligence and the Internet of Things offer also new opportunities for new forms of policy design, implementation, and assessment providing more personalised support to those who need it and being more participative throughout the policy cycle. The use of digital twins, gaming, simulation, and synthetic data are just at their beginning but promise to change radically the relationships among all the stakeholders in governance of our society
Tõrked Eesti venekeelse kirjanduse omaks tunnistamisel 1918–1940. Igor Severjanini juhtum
No full textThe article looks at the history of Estonian Russian-language literature in the young Republic of Estonia (1918–1940) and the life and work of the Russian-speaking poet Igor Severyanin (1887–1941) from the perspective of Estonian literature. In 1918, Severyanin, as a mature author, moved permanently from Russia to Estonia. Gradually, he developed a hybrid identity: he became fond of Estonia and wrote in Russian. However, his works have been omitted from the Estonian literary history.
The article sets out the following hypotheses:
1) Estonian Russian-language literature from 1918 to 1940 has not become part of Estonian literature of that period, as its acceptance is hindered by various cultural-historical barriers for literary researchers. The main barriers have been highlighted by means of source criticism.
2) Igor Severyanin’s life and work serve to situate him as a representative of Estonian literature. Terms such as integration and identity were not used in his day, but Severyanin’s personal and creative choices help to understand, retrospectively, that it was important for him to live in Estonia, write poetry inspired by local material, interact with Estonian-speaking colleagues, remain connected with Estonian public and cultural institutions. I have approached Severyanin’s case through the identity theory (the work of John Charles Turner and Homi Bhabha), as well as Pierre Bourdieu’s concept of the literary field.
Both hypotheses were confirmed in the article. However, the values of modern multicultural society dictate that the discussion of Estonian literary history should include the Russian-speaking authors of the interwar period. Currently, there are gaps in Estonian literary history regarding these authors. Filling these gaps would mean overcoming the cultural-historical barriers
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