1,720,967 research outputs found
High transparent matched window for standing wave linear accelerators
No full textThis paper proposes a particular Dielectric Window (DW) for Standing Wave (SW) Linear Accelerators
(LINAC’s). This study investigates the in-frequency return loss behaviour of the LINAC, in order to improve
matching and transmitting conditions while maintaining the optimum coupling between LINAC and High Power Microwave (HPMW) source. Device design considers the DW input interface as an Input Matching Network (IMN) at the LINAC Normal Mode (NM) working frequency.
Thus, design formulas are provided and Computer Aided Design (CAD) techniques are proposed.
A prototype has been made and tested by performing cold S-parameter and Percentage Depth Dose (PDD)
measurements of a LINAC with the proposed DW and with a traditional DW.
The proposed device offers more energy transport attitude over the traditional DW, as shown by a return loss
increase of 167 % and an output electron energy increase of 5.5% while maintaining the same LINAC input power settings. This solution can offer a decrease of power line size, weight and cost
Tuned Window for Standing Wave Linear Accelerators
No full textThis paper proposes a dielectric window for Standing Wave Linear Accelerators (LINAC's) which can be tuned after brazing and welding, in order to compensate the electro-magnetic alteration due to these production processes. This study investigates the in-frequency return loss behavior of the LINAC, in order to improve matching and transmitting conditions while maintaining the optimum coupling between LINAC and High Power Microwave (HPMW) source. Device design is single-frequency based and considers the dielectric window interface as an Input Matching Network (IMN) at the LINAC normal mode working frequency. Thus, design formulas are provided and Computer Aided Design techniques are proposed. A prototype has been made and tested by performing cold S-parameter measurements of a LINAC with the proposed dielectric window and with a traditional dielectric window. The proposed device offers more energy transport attitude over the traditional dielectric window, as shown by a return loss increase of 167% of the complete system
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
Tuned Window for Standing Wave Linear Accelerators
No full textThis paper proposes a dielectric window for Standing Wave Linear Accelerators (LINAC’s) which can be tuned after brazing and welding, in order to compensate the electro- magnetic alteration due to these production processes. This study investigates the in-frequency return loss behavior of the LINAC, in order to improve matching and transmitting conditions while maintaining the optimum coupling between LINAC and High Power Microwave (HPMW) source. Device design is single-frequency based and considers the dielectric window interface as an Input Matching Network (IMN) at the LINAC normal mode working frequency. Thus, design formulas are provided and Computer Aided Design techniques are proposed. A prototype has been made and tested by performing cold S-parameter measurements of a LINAC with the proposed dielectric window and with a traditional dielectric window. The proposed device offers more energy transport attitude over the traditional dielectric window, as shown by a return loss increase of 167% of the complete system
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
Electron Beam Detection by Induced Resonance in Cylindrical Cavity
Get PDFAn investigation on the power energy injection in a resonator by electron stream is
reported in this paper, by documenting the power transfer from an electron beam to a resonant
cavity, coupled to an external circuitry. The proposed system has been employed to measure the
radiation dose deposed by a medical electron linear accelerator. A prototype has been fabricated
and tested through VNA cold measurements and dose deposition measurements. A microcon-
troller system has been employed to obtain a digital output, the Monitor Units. The linearity of
the Monitor Units for di®erent values of accumulated dose, have allowed to employ this system
for the real time dose measurements
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