101,857 research outputs found
An Efficient Method to Design Planar Arrays for High Power Applications by Mutual Coupling Optimization
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Multiphysics Design and Experimental Verification of a Quad-Band Dichroic Mirror for Deep Space Ground Stations
No full textThis study presents the multi-disciplinary approach used to study a quad-band dichroic mirror to be installed in the European Space Agency deep space antennas. Traditional electromagnetic (EM) analyses based on a uniform plane wave incidence were augmented by advanced numerical techniques to investigate the impact of the dichroic mirror on the overall antenna performance. In addition, along with the EM design, a parallel study considering mechanical, thermal and power-handling aspects allowed their impact on the EM behaviour of the dichroic mirror to be evaluated. This comprehensive study permitted an optimum design to be achieved for the dichroic mirror, which accounts for the actual operational conditions of the mirror itself when installed in the antenna. The device was manufactured and measured, verifying also the mechanical and thermal theoretical predictions, obtaining an excellent agreement between simulations and experimental results
A X/K/Ka-band Dichroic Mirror for ESA Deep Space Antennas
No full textThis paper presents a complete overview of the project activity for a new dichroic mirror to replace the actual unit (M6, currently installed in the DSA2, Cebreros, Spain).
The required specifications and constraints, the analysis and design tools adopted and the design of the dichroic mirror are also discussed. The manufacturing, testing and measuring techniques adopted to fabricate, verify and measure this dichroic mirror are presented.
The new dichroic mirror discussed in this paper is due to be installed at the same nominal incidence angle of the actual unit and it will transmit the Ka-band Rx and the Ka-band Tx channels while it will reflect the X-band Rx, X-band Tx channels and K-band (25.5–27 GHz).
For all frequencies, the dichroic mirror will be able to operate with Left-Hand Circular Polarisation (LHCP) and Right-Hand Circular Polarisation (RHCP) simultaneously.
A detailed mechanical model of the dichroic mirror has been implemented to simulate the thermo-elastic behaviour of the entire mirron in operation.
The structure is modeled assuming two different elastic materials: the external ring composed of solid bulk material (aluminium alloy), and the perforated central part considered as a continuum orthotropic elastic material.
In particular, the mechanical and thermal parameters of the perforated area have been retrieved by numerical simulation of a significant portion of the perforated area itself.
The thermal analysis takes into account the internal conduction and the convection operated along the external surface of the mirror and through the perforated part of the plate by the surrounding air applying an ambient temperature of 20 °C
Multi-physics Design and Manufacturing of a Quad-band Frequency Selective Surface for Space Applications
No full textBibliographie Hilarion G. Petzold 1958 – 2009 mit Anhang als Einführung
No full textDieses Archiv enthält die Gesamtbibliographie der Werke des Autors nebst einiger Texte „Über H. G. Petzold“ im Schlussteil der Bibliographie sowie einen Anhang mit einer Einführung in die Architektur des Werkes in seinem wissenslogischen Aufbau als Ausarbeitung seines „Tree of Science Modells“ (2007).This archive contains the complete bibliography of the author and some texts about H. G. Petzold, moreover an epilogue with an introduction to the architecture of the works in its epistemological structure and composition and as an elaborations of Petzold’s „Tree of Science Modell (2007).https://www.fpi-publikation.de/polyloge/01-2009-petzold-h-g-gesamtbibliographie-h-g-petzold-1958-2009-updating-november2009/peerReviewedpublishedVersio
Dispelling the Myths Behind First-author Citation Counts
No full textWe 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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3346: Samuel G. Freedman, author, 2013
No full textPhotograph of author Samuel G. Freedman, at NT Daily Slash meeting in the Mayborn School of Journalism at UNT
The Right to Strike under the United States Constitution: Theory, Practice, and Possible Implications for Canada
No full textAnswering critics of the Canadian Supreme Court's judgment in B.C. Health, the author argues that the Court laid the foundation for a principled and durable doctrine protecting constitutional labour rights, one that goes directly to the heart of the matter — the inequality of workers’ power in the employment relation. In the author’s view, two paths could lead from B.C. Health to the recognition of Charter protec- tion for a right to strike: one that treats the right as an accessory to col- lective bargaining, and one that upholds the right directly on the basis of the Charter values of equality and participation. The author supports the latter approach, contending that constitutional rights should be defined in relation to fundamental values, in a way that is not contingent on time-bound or fact-sensitive assessments about the role of strikes within a particular collective bargaining regime. Although a Charter right to strike may involve the courts in difficult choices about when to defer to legislative policy decisions, and courts may lack the institutional capac- ity to deal effectively with labour law issues, the author points out that judges can look to ILO standards for expert guidance. Noting that the U.S. experience in this area might be of considerable use to Canadians, the author concludes by providing an overview of American case law concerning a constitutional right to strike.Peer reviewe
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