Global ETD Search

21	Schwingungsanalyse an Maschinen mit ungleichförmig übersetzenden Getrieben Zschieschang, Torsten 09 November 2000 (has links) Die Arbeit befaßt sich mit Methoden der Identifikation von Schwingungsursachen anhand gemessener Schwingungssignale an Maschinen mit ungleichförmig übersetzenden Getrieben. Den technischen Hintergrund bilden die Verarbeitungsmaschinen, die als ein Haupteinsatzgebiet der auch als Mechanismen bezeichneten Getriebe gelten. Es werden eine ganze Reihe mechanismentypischer Schwingungsursachen untersucht, die im wesentlichen auf Elastizitäten, veränderliche Parameter, Spiel, Reibung und Unstetigkeiten in den Lagefunktionen zurückzuführen sind. Neben den traditionellen Methoden der Signalanalyse gilt das Hauptaugenmerk den neuen Methoden der Zeit-Frequenz-Analyse, die dem zumeist instationären Charakter der durch die Mechanismen verursachten Schwingungen gerecht werden. Dazu zählen vor allem lineare Transformationen wie die Kurzzeit-Fourier- oder die Wavelet-Transformation, quadratische Verteilungen aus Cohen's Klasse wie die Wigner-Ville und die Choi-Williams Verteilung oder auch höhere Transformationen wie die Adaptive Optimal Kernel oder die Reassignment Methode. Die Untersuchungen münden in einer tabellarischen Zusammenstellung der gefundenen Merkmale. Diese soll der Unterstützung der praktischen Signalanalyse bei Mechanismenschwingungen dienen. Die Anwendung der zur Verfügung stehenden Mittel und Methoden wird an zahlreichen Beispielen aus dem Bereich der Schwingungsdiagnose an Verarbeitungsmaschinen demonstriert. - - - Diese Version ersetzt eine ältere Version, Grund: Formatkonvertierung postscript zu pdf. Der Inhalt unterscheidet sich in der Qualität der Abb. 4.23a und 4.23b auf Seite 97 sowie aller Abbildungen auf Seite 111. Der Zugriff auf die Original-Abb. ist über die ältere Version oder die gedruckte Ausgabe möglich. Die gedruckte Ausgabe der Dissertation ist in der Universitätsbibliothek Chemnitz entleihbar. / This thesis deals with methods to identify causes of vibrations by investigation of messured signals at machines with mechanisms (with varying velocity ratio). The technical background is the field of manufacturing machines, the main application of such mechanisms. Inspected are the most typical causes of vibrations at mechanisms that comes with elasticity, variable parameters, clearance, friction or nonsmooth transferfunctions. There are used both, traditional methods of signal analysis and time-frequency-analysis methods that are especially advantageous for the often instationary vibrations at this kind of machines. Linear transformations like the Short-Time-Fourier- or the Wavelet-Transformation, quadratic distributions from Cohe's Class like the Wigner-Ville- or the Choi-Williams-Distribution and higher order transformations like the Adaptive Optimal Kernel or the Reassignment Method are used in this Paper. The investigation leads into a tabular form of characteristics wich should be used for identification of vibrational causes during vibrational analysis. The use of available methods is demonstrated by solving various examples on real manufactoring machines. - - - This version replaces an older version, reason is conversion of format from postscript to pdf. Content is different in quality of pictures 4.23a and 4.23b on page 97 and all pictures on page 111. Please see the original pictures in the older version or the printed version. The printed version is borrowable at the Library of Chemnitz University of Technology. info:eu-repo/classification/ddc/620 ddc:620 Signalanalyse Wigner-Verteilung Zeit-Frequenz-Analyse Choi-Williams-Distribution Choi-Williams-Verteilung Mechanismen (Maschinendynamik) Merkmale Schwingungsdiagnose Schwingungsursachen Verarbeitungsmaschinen Wavelets Wigner-Ville-Distribution Wigner-Ville-Verteilung causes of vibrations characteristics manufacturing machines mechanism (with varying velocity ratio) signal analysis time-frequency-analysis vibrational diagnostic wavelets
22	A school-based case study Kwan, Che-ying., 關之英. January 1995 (has links) published_or_final_version / Education / Master / Master of Education Creative writing.
23	Religious Media Use And Audience's Knowledge, Attitude, And Behavior: The Roles Of Faith Motivation, Program Appeals, And Dual Information Processing Yoon, Kisung 24 March 2011 (has links) No description available. Mass Communications Mass Media Religious Media Religious Drama Exposure Religious Media Programming Media Effect Uses and Gratifications Faith Motivation Elaboration Likelihood Model Rational Appeal and Emotional Appeal Korean Catholic Church History Father Choi Yang Up
24	Planning an elderly dental programme in a public housing estate Yu, Sek-ho, Felix., 余錫豪. January 1993 (has links) published_or_final_version / Dentistry / Master / Master of Dental Surgery Planned communities - China - Hong Kong. Dental surveys - China - Hong Kong. Older people - Dental care. Choi Hung Estate - Older people. Social surveys - Older people.
25	Black Food Trucks Matter: A Qualitative Study Examining The (Mis)Representation, Underestimation, and Contribution of Black Entrepreneurs In The Food Truck Industry Ariel D Smith (14223191) 11 August 2023 (has links) <p>Food trucks have become increasingly popular over the last decade following the Great Recession of 2008. Scholars have begun to study the food truck phenomenon, its future projected trajectory, and even positioning it within social justice discourse along cultural lines; however, scholarship has yet to address the participation of Black entrepreneurs in the food truck industry.</p> <p><br></p> <p>The objective of this dissertation is to expand the perception of Black food entrepreneurs within the food truck industry by interrogating how Black food truck owners are misrepresented, under analyzed, and underestimated. Using a series of interdisciplinary qualitative methods including introspective analysis, thematic coding analysis, and case studies, I approach this objective by addressing three questions. First, I analyze movies and television to understand where Black-owned food trucks are represented in popular culture and how they are depicted. In doing so, we come to understand that Black business representation, specifically Black food truck representation consistently falls victim to negative stereotypes. These stereotypes can influence the extent to which Black food truck owners are taken seriously and seen as legitimate business leaders in their community. Second, I interview 16 Black food truck entrepreneurs to understand why the mobile food industry appealed to them and how it has become a platform for them to explore other opportunities. Finally, I review eight cities that have launched Black food truck festivals and parks within the last 6 years to gain an understanding of the collective power wielded by Black food truck owners and its impact Black communities. Moreover, this dissertation challenges the myth that collectivism does not exist among Black entrepreneurs and the Black community broadly.</p> Business systems in context Food and hospitality services Business and labour history Entrepreneurship Cinema studies Screen media Digital heritage Heritage and cultural conservation Heritage collections and interpretations Social and cultural anthropology Urban community development Sociology of inequalities Urban sociology and community studies Media studies Consumption and everyday life Cultural and creative industries Cultural studies of nation and region Culture, representation and identity Screen and media culture Food Truck food trucks Black owned Black owned food truck mobile food street food street food vending street food entrepreneurship Black food Black food truck studies food truck studies African American Studies African American foodways Black foodways Black food entrepreneurship Black movies Black television The Food Truck Scholar The Food Truck Scholar Podcast Black business Black businesses Barbershop 3 The Last OG The Chi Think Like a Man food truck festivals food truck park foodtruck Roi Choi The Great Food Truck Race Chef Chef movie Black representation Black men Black women Black men representation Black women representation critical race theory case study introspective analysis Black entrepreneurs African American entrepreneurs food truck industry mobile food vending Black food truck owner Black food truck entrepreneur food truck owner food truck operator food trucker Black food trucker African American food truck owner African American food trucker food truck podcast food truck show storytelling African American storytelling Black studies africana studies entrepreneurial storytelling food studies Black food studies African American food studies enterprise food truck enterprise Black food trucks matter Black businesses matter Buy Black Black dollars Black economics Black dollar soul food southern studies Black diaspora \

Page generated in 0.0384 seconds