1,721,210 research outputs found
Gewässergütekarte der Landeshauptstadt Hannover
Get PDFGEWÄSSERGÜTEKARTE DER LANDESHAUPTSTADT HANNOVER
Gewässergütekarte der Landeshauptstadt Hannover / Schmidt, Dirk [Textverf.] (Rights reserved) (-
Leben mit dem Klimawandel
Get PDFLEBEN MIT DEM KLIMAWANDEL
Leben mit dem Klimawandel / Schmidt, Dirk (Rights reserved) (-
Adaptive optics with an infrared Pyramid wavefront sensor
Get PDFWavefront sensing in the infrared is highly desirable for the study of M-type stars and cool red objects, as they are sufficiently bright in the infrared to be used as the adaptive optics guide star. This aids in high contrast imaging, particularly for low mass stars where the star-to-planet brightness ratio is reduced. Here we discuss the combination of infrared detector technology with the highly sensitive Pyramid wavefront sensor (WFS) for a new generation of systems. Such sensors can extend the capabilities of current telescopes and meet the requirements for future instruments, such as those proposed for the giant segmented mirror telescopes. Here we introduce the infrared Pyramid WFS and discuss the advantages and challenges of this sensor. We present a new infrared Pyramid WFS for Keck, a key sub-system of the Keck Planet Imager and Characterizer (KPIC). The design, integration and testing is reported on, with a focus on the characterization of the SAPHIRA detector used to provide the H-band wavefront sensing. Initial results demonstrate a required effective read noise <1e^– at high gain
Experimental study on the performance of the standardized test method for detonation flame arresters
No full textFlame arresters are autonomous protection systems and are among the constructive explosion protection measures that limit the effects of an explosion.
In this study, the performance of the standardized test method regulated in the DIN EN ISO 16852 standard for in-line flame arresters for stable and unstable detonations, which is mainly designed for atmospheric conditions, is examined. In an interlaboratory comparison, experiments are performed for different pressures before ignition and explosion groups according to the standardized test method. The experimental data is analyzed in detail to further optimize the test method and to thus achieve an improved reproducibility of detonation tests at high pressures, especially regarding the deflagration to detonation transition.
Based on these results, an improved test method for detonation flame arresters will be developed, which will ensure better reproducibility as well as applicability under non-atmospheric conditions
Simulation und experimentelle Untersuchungen der Schwergasausbreitung
No full textAufgrund gestiegener Rechnerleistung finden heutzutage numerische Strömungssimulationen aus dem
Bereich der CFD (Computational Fluid Dynamics) immer mehr Eingang in die Sicherheitstechnik. Bisherige Berechnungsverfahren zur
Schwergasausbreitung basieren zum Teil auf empirischen Annahmen und sind in ihrem Anwendungsbereich eingeschränkt. Die zugrunde liegenden
Formeln und Theorien erlauben außerdem meist nur eindimensionale Aussagen bezüglich der Konzentrationsverteilung in der Umgebung. Anhand von
Literaturdaten und eigenen Freifeldversuchen zur Schwergasausbreitung soll die Leistungsfähigkeit von CFD-Berechnungen hinsichtlich ihres
Kosten/Nutzen-Verhältnisses sowie im Vergleich zu herkömmlichen Modellen bewertet werden. Während die eigenen Freifeldversuche hauptsächlich
zur Validierung der numerischen Simulationen dienen, können anhand der in der Literatur veröffentlichten Daten Vergleiche mit z. B. der
VDI-Richtlinie 3783, Blatt 2 durchgeführt werden
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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