1,720,958 research outputs found
Optimierung der Steuerung des nationalen Bezugsnormals zur Darstellung der Kraft im nationalen Metrologieinstitut in Österreich
Get PDFDem Bundesamt für Eich- und Vermessungswesen (BEV) unterliegt als nationales Metrologieinstitut (NMI) Österreichs die Darstellung der Kraft und die korrekte Weitergabe der Einheit Newton an Wirtschaft und Industrie. Das BEV verfügt hierzu über eine primäre Kraftanlage, welche für die Kraft im Bereich weniger Newton bis in den Meganewton-Bereich das österreichische Normal darstellt. Durch die langjährige Nutzung der Kraftanlage treten Abnutzungserscheinungen auf, welche die Qualität der Messung negativ beeinflussen. Die auftretenden Störungen in Form von Stößen und Schwingungen beim mechanischen Form- und Kraftschluss bei der Belastung des Prüflings können insbesondere im Bereich kleinerer Kräfte zu Lastspitzen führen, welche Kraftaufnehmer überlasten oder in ihr Hystereseverhalten bringen können. Somit werden die Messwerte verfälscht und die Genauigkeit der Messung wird verringert. Im Rahmen dieser Arbeit soll ein Konzept für die Regelung der Anlagensteuerung und die dabei auftretende Probleme sowie deren Lösungen erarbeitet. Anschließend sollen die gefundenen Ansätze realisiert und in der bestehenden Anlage implementiert werden. Dazu wurde das Verhalten der Anlage bei verschiedenen Messbereichen und Kraftaufnehmern analysiert und anschließend mittels verschiedener Optimierungsverfahren geeignete Regelparameter entwickelt. Außerdem wurde die Möglichkeit der Definition verschiedener Regelparameter auf Basis mathematischer Funktionen untersucht. Die Validierung der Optimierung der Regelparameter erfolgte durch interne Vergleichsmessungen mit Transfernormalen des Physikalisch-technischen Prüfdiensts über den gesamten Messbereich der Kraftanlage. Die Messdaten wurden entsprechend der Vorgaben für die Kalibrierung von Kraftaufnehmern ausgewertet und dargestellt. Anschließend wurde anhand von definierten Kriterien die Qualität der Optimierungen bewertet. Dazu wurde auch ein Messunsicherheits-Budget für die Kraftanlage erstellt und mit dem aktuellen Anlagenzustand verglichen. Somit wurde ein umfangreicher Nachweis der Funktionalität der Kraftanlage erbracht. Es konnte gezeigt werden, dass durch die Verwendung von optimierten Regelparametern bei dem Betrieb der Kraftanlage des BEVs eine deutliche Verbesserung der Wiederholpräzession und der Messgenauigkeit erreicht werden konnte und die Messunsicherheit der Kraftmessung dabei verringert wurde.As Austria's national metrology institute (NMI), the Federal Office for Calibration and Surveying (BEV) it is tasked with providing the national etalon of force and to correctly transfer the unit Newton to business and industry. For this purpose, the BEV has a primary force machine representing the Austrian standard for the force in the range of a few Newtons up to the Meganewton range.Due to the long-term use of the force machine, signs of wear appear. These cause disruptions that occur in the form of impacts and vibrations during the measurement and affect the quality of the measurement. Especially in areas of lower force the occurring peaks in force can overload the force transducer or show its hysteresis behavior. As a result, the measured values are falsified and the accuracy of the measurement is reduced.As part of this work, a concept for the improvement of the control system parameters is developed in order to reduce the effects caused by the occurring disturbances. The approaches found are then to be implemented in the existing system. In addition, the possibility of defining various control parameters on the basis of mathematical functions was examined.The optimization of the control parameters was validated by internal comparison measurements using transfer standards provided by the Physikalisch-technischer Prüfdienst (PTP) to validate the behavior of the force machine over its entire measuring range. The measurement data was evaluated and presented in accordance with the specifications for the calibration of force transducers. The quality of the optimizations was then evaluated using defined criteria. Furthermore, a budget of measurement uncertainty was created for the force machine. Thus, extensive proof of the functionality of the force machine was provided. It was shown that the use of optimized control parameters during measurements could achieve a significant improvement in the repeatability and the measurement accuracy, therefore reducing the measurement uncertainty of the force measurement
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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