1,720,955 research outputs found
Optimal Design of Hybrid Magnets
No full textContinuous very high magnetic fields (over 30 T) can be generated using suitable combinations of superconducting and resistive magnets. Devices of such class are mainly used for research purposes, and are available at a few laboratories all over the world. The combined use of superconducting and resistive technologies calls for very demanding design effort, since the thermal and mechanical behavior of the two parts of the magnet present different characteristics, but both are pushed to their limits due to the very high field strength. As a matter of fact, a model of a hybrid magnet behavior to be used for computer aided design would require to keep into account the thermal aspects of the resistive part to dimension the cooling system, the possible start of quench in the superconducting part, the computation of mechanical forces for the stress analysis, and finally the connection to the power supply system, to properly include a protection system for the magnet. On the other hand, under suitable hypotheses, some simplifications are possible and analytical models are available, making the optimized design of such magnets a feasible task in reasonable computation times. The possibility of achieving the required performance eventually using different layouts calls for the adoption of broad search optimization algorithms able to search the whole design space without being trapped in local minima. As an example, stochastic, population-based algorithms such as Genetic Algorithms or Particle Swarm Optimization algorithms present the required characteristics. In the paper, an optimized design procedure, based broad search algorithms, for high field hybrid magnets, able to take into account the complex behavior of hybrid magnets, will be proposed
Flexible Measures in Magnetic Active Shielding
No full textBrowse Conference Publications > Electromagnetic Field Computa ...
Flexible measures in magnetic Active Shielding .This paper appears in:
Electromagnetic Field Computation (CEFC), 2010 14th Biennial IEEE Conference on
Date of Conference: 9-12 May 2010
Author(s): Formisano, A.
Dip. Ing. dell'Inf., Seconda Univ. di Napoli, Aversa, Italy
Lupoli, M.C. ; Martone, R.
Page(s): 1
Product Type: Conference Publications
5481633 searchabstract .Abstract
The reduction in protected regions of low frequency magnetic fields is a complex problem when the sources are not known. The paper proposes a procedure able to choose the best currents able to mitigate the disturbance field. The magnetic field is represented by suitable series of eigenfunctions in the domain of interest. The procedure includes a field identification step starting from a set of measurements and a current design step, possibly based on a preliminary design of specialized shimming coils sets
Shaping of Source Currents for ECT of non Circular Tubes
No full textAn automated Eddy Current Testing (ECT) method to inspect non circular metallic tubular parts, usually inspected manually, is presented. The basic idea is to project (physically or virtually) the sources of a classical rotating field ECT device on a surface following the profile of the inspected tube, in order to get a “travelling field”, giving the same possibilities as rotating field for ECT of circular tubes. In this paper a “physical” projection of source currents will be used to demonstrate that the “projected” field map achieves better performance than the use of standard rotating field, in the second part it is presented the procedure to get a “virtual” sources projection in order to use an excitation system positioned on a cylindrical geometry to investigate a tube with generic cross-section. In this paper for exemplification purpose an elliptical tube is investigated
Optimal Design of Measurement Systems for Current Distribution Measurement in Parallel Cables
No full textPurpose – The purpose of this paper is to propose the optimal allocation and alignment of probes for
current distribution measurement (CDM) in the case of twin cable in conduit conductor (CICC) cables
with equal and opposite current.
Design/methodology/approach – The most effective approach to CDM in CICC cables is to perform
indirect measurements starting from magnetic field map measured externally to the cable. A number of
approaches have been proposed to optimize the layout of magnetic field probes external to the cable, but
all dealing with single cables. In this paper, an approach to the optimized design of measurement system
for twin cables will be proposed, based on the minimization of a suitable cost function.
Findings – A method for the optimal allocation of probes both in terms of rejection of the
background field and of condition number of the Green matrix has been defined.
Research limitations/implications – The method is valid only in the hypothesis of linear
relationship between currents and magnetic field.
Practical implications – The proposed approach allows to design more robust CDM systems, with
increased noise and background field rejection capability.
Originality/value – The problem of optimal design of CDM systems has been previously tackled in
literature, but typically with reference to single cables. In the paper, an approach able to explicitly deal with twin cables is proposed
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe 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
Variations on the Author
Get PDF“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Get PDFWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Get PDFWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
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