1,720,961 research outputs found
Experimental investigation of multiphase flow and acoustics during voice production
Get PDFThis dissertation advances the understanding of human phonation by integrating biomechanical modeling, aerosol analysis, and acoustic evaluation in a single comprehensive framework. First, a biomimetic, multi-layered synthetic larynx model was developed to replicate key features of human vocal fold physiology. By embedding ligament fibers with varying diameters and tensile strengths, the model allows controlled posturing (elongation, abduction, adduction) and dynamic manipulation of vocal fold stiffness. Systematic experiments revealed that increased fiber tension raises fundamental frequency and subglottal pressure, closely mirroring physiological observations of pitch regulation and providing a robust platform for studying both healthy and pathological voice conditions.
In a second step, the thesis elucidates aerosol formation mechanisms during phonation by combining the synthetic larynx model with synthetic mucus formulations that replicate human laryngeal mucus properties. Detailed high-speed imaging and particle image velocimetry showed that reduced surface tension and increased airflow reinforce aerosol particle generation, emphasizing the influence of mucus rheology and vocal fold dynamics on droplet release at the glottal level. These findings have direct implications for understanding transmission risks of airborne pathogens during speech and singing.
Finally, the acoustic effects of professional singing masks were investigated to reconcile infection control measures with vocal performance demands. Tests on a KEMAR head phantom demonstrated that although specialized fabrics and plastic face shields can mitigate frontal aerosol dispersion, they also introduce measurable spectral filtering of the acoustics, especially at higher frequencies. Some designs additionally cause low frequency amplification or altered directional radiation, potentially compromising vocal quality and clarity.
Collectively, this work integrates advanced physical modeling of physiological vocal fold oscillation with applied aerosol dispersion during phonation and the impact on the resulting acoustics. The outcomes not only enhance fundamental knowledge of vocal fold biomechanics but also support evidence-based strategies for safeguarding public health improving vocal performance in professional and educational settings, as well as addressing clinical needs.Diese Dissertation erweitert das Verständnis der menschlichen Stimmgebung, indem sie biomechanische Modellierung, Aerosolgenerierung und -ausbreitung und akustische Untersuchungen in einem umfassenden Forschungsansatz vereint. Zunächst wurde ein biomimetisches, mehrschichtiges synthetisches Larynxmodell entwickelt, das zentrale Aspekte der menschlichen Stimmlippenphysiologie abbildet. Durch die Integration von Ligamentfasern unterschiedlicher Durchmesser und Zugfestigkeiten ermöglicht das Modell eine gezielte Veränderung von Elongation, Adduktion und Abduktion sowie eine dynamische Anpassung der Steifigkeit der Stimmlippen. Systematische Experimente zeigten, dass eine höhere Faserspannung sowohl die Grundfrequenz als auch den subglottalen Druck erhöht und somit die menschliche Stimmgebung realistisch nachbildet. Damit bietet das Modell eine robuste Plattform, um gesunde und pathologische Zustände der Phonation zu untersuchen.
Im zweiten Schritt beleuchtet die Arbeit die Entstehung von Aerosolen während der Phonation, indem das synthetische Larynxmodell mit synthetischem Mukus kombiniert wurde, der die viskoelastischen Eigenschaften von menschlichem laryngealen Mukus nachahmt. High-speed Videoaufzeichnungen der Stimmlippenschwingung und Strömungsvisualisierung im supraglottalen Bereich zeigen, dass eine verringerte Oberflächenspannung des Mukus und ein erhöhter Luftstrom die Bildung von Aerosolpartikeln verstärken. Dies unterstreicht den Einfluss der Mukusrheologie und Stimmlippendynamik auf die Partikelentstehung auf glottaler Ebene und liefert wertvolle Erkenntnisse für die Bewertung von Infektionsrisiken bei Sprech- und Gesangstätigkeiten.
Abschlie\ss end wurden die akustischen Auswirkungen professioneller Sängermasken untersucht, um Infektionsschutzmaß nahmen mit den Anforderungen an die stimmliche Lei\-stungsfähigkeit zu vereinen. Versuche an einem KEMAR-Kopf belegten, dass spezielle Stoffe und transparente Kunststoffe zwar den frontalen Aerosolausstoß reduzieren, jedoch gleichzeitig deutlich hörbare akustische Filtereffekte, insbesondere bei hohen Frequenzen, hervorrufen. Zusätzlich können bestimmte Maskentypen zu einer Verstärkung tiefer Frequenzen oder einer veränderten räumlichen Schallabstrahlung führen und damit Klangqualität und Verständlichkeit beeinträchtigen.
Zusammenfassend vereint diese Arbeit die physikalische Modellierung physiologischer Stimmlippenschwingungen mit der praxisnahen Untersuchung von Aerosolausbreitung während der Phonation und den Einfluss auf die resultierende Akustik beim Tragen von Masken, um die Ausbreitung von Aerosolen zu reduzieren. Die Ergebnisse tragen nicht nur zu einem vertieften Grundlagenverständnis der Biomechanik der Stimmlippen bei, sondern unterstützen auch evidenzbasierte Strategien zum Schutz der öffentlichen Gesundheit, zur Verbesserung der stimmlichen Leistungsfähigkeit in beruflichen und pädagogischen Kontexten sowie zu Optimierungen im klinischen Betrieb
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
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
Author Under Sail The Imagination of Jack London, 1893-1902
No full textIn Author Under Sail, Jay Williams offers the first complete literary biography of Jack London as a professional writer engaged in the labor of writing. It examines the authorial imagination in London's work, the use of imagination in both his fiction and nonfiction, and the ways he defined imagination in the creative process in his business dealings with his publishers, editors, and agents. In this first volume of a two-volume biography, Williams traverses the years 1893 to 1902, from London's "Story of a Typhoon" to The People of the Abyss. The Jack London who emerges in the pages of Author Under Sail is a writer whose partnership with publishers, most notably his productive alliance with George Brett of Macmillan, was one of the most formative in American literary history. London pioneered many author models during the heyday of realism and naturalism, blurring the boundaries of these popular genres by focusing on absorption and theatricality and the representation of the seen and unseen. London created an impassioned, sincere, and extremely personal realism unlike that of other American writers of the time. Author Under Sail is a literary tour de force that reveals the full range of London as writer, creative citizen, and entrepreneur at the same time it sheds light on the maverick side of machine-age literature.Intro -- Title Page -- Copyright Page -- Dedication -- Contents -- Acknowledgments -- Introduction -- 1. Spirit Truth -- 2. From Absorption to Theatricality and Back Again -- 3. "I Will Build a New Present" -- 4. Sons as Authors -- 5. Fathers as Publishers -- 6. The Daughter as Author -- 7. Lovers as Authors -- 8. At Sea with the Family -- 9. Yellow News, Yellow Stories -- 10. The Return Home -- Notes -- Bibliography -- Index -- About Jay WilliamsIn Author Under Sail, Jay Williams offers the first complete literary biography of Jack London as a professional writer engaged in the labor of writing. It examines the authorial imagination in London's work, the use of imagination in both his fiction and nonfiction, and the ways he defined imagination in the creative process in his business dealings with his publishers, editors, and agents. In this first volume of a two-volume biography, Williams traverses the years 1893 to 1902, from London's "Story of a Typhoon" to The People of the Abyss. The Jack London who emerges in the pages of Author Under Sail is a writer whose partnership with publishers, most notably his productive alliance with George Brett of Macmillan, was one of the most formative in American literary history. London pioneered many author models during the heyday of realism and naturalism, blurring the boundaries of these popular genres by focusing on absorption and theatricality and the representation of the seen and unseen. London created an impassioned, sincere, and extremely personal realism unlike that of other American writers of the time. Author Under Sail is a literary tour de force that reveals the full range of London as writer, creative citizen, and entrepreneur at the same time it sheds light on the maverick side of machine-age literature.Description based on publisher supplied metadata and other sources.Electronic reproduction. Ann Arbor, Michigan : ProQuest Ebook Central, YYYY. Available via World Wide Web. Access may be limited to ProQuest Ebook Central affiliated libraries
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