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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Effects of Single Panel Replacement of a Full-Scale, Full-Depth, Precast Concrete Bridge Deck System

Perry, Jason Robert 01 August 2012 (has links)
The use of precast concrete deck panels is becoming increasingly popular for bridge construction and rehabilitation in the state of Utah and across the country. It allows for the use of full depth concrete deck panels but removes the long construction times of traditional cast-in-place methods. One of the challenges to the use of precast deck panels is the transverse deck panel joints that exist between the panels. These joints are unreinforced using traditional methods and therefore are the weakest section of the bridge. In many situations the joint will fail and water seeps through and can damage the bridge superstructure. Post-tensioning of precast decks has become the standard. The post-tensioning provides reinforcing through the joints, reducing the cracking that occurs. Additionally, the post-tensioning provides pressure along the joint and closes cracks that have occurred, therefore preventing water from leaking through to the superstructure and damaging it. The Utah Department of Transportation uses post-tensioning cables that run along the length of the bridge deck, applying pressure on the joints. One of the problems with using this method is it does not allow for the replacement of a single deck panel should the need arise. Utah State University has been researching a new post-tensioned connection that would allow for the replacement of a single deck panel. The “curved bolt” connection connects each deck panel to adjacent panels, providing reinforcement and post-tensioning along the joint. Laboratory testing was undertaken to investigate the effects of single panel bridge rehabilitation on the existing deck system.
2

Analog Feedback Control of an Active Sound Transmission Control Module

Sagers, Jason Derek 09 July 2008 (has links) (PDF)
This thesis provides analytical and experimental proof-of-concept for a new feedback-controlled sound transmission control module for use in an active segmented partition (ASP) array. The objective of such a module is to provide high transmission loss down to low audible frequencies while minimizing the overall mass of the module. This objective is accomplished in the new module by using actively controlled panels in conjunction with analog feedback controllers. The new module also overcomes two limitations that exist in current ASP modules: the inability to control broadband random-noise and the lack of bidirectional control through the module. Overcoming these limitations represents an important advancement in the research area of actively controlled partitions and broadens the number of potential applications for ASP arrays. Analogous circuit models were developed and used to predict the performance of the new ASP module under feedback control. The preliminary design consists of two loudspeaker drivers mounted back-to-back in a duct, with two decoupled analog feedback controllers connected to reduce the vibration of the loudspeaker cones. It was found that the classical analogous circuit model of a loudspeaker proved inadequate for modeling the low- and mid-frequency transmission loss due to resonance effects of the loudspeaker surround. An enhanced model of a loudspeaker was then used to account for this phenomenon and more accurately predict the transmission loss behavior. An experimental proof-of-concept module was constructed using two 10 cm diameter loudspeaker drivers, two accelerometers, and other off-the-shelf materials. The two analog feedback controllers used in the module were designed and built using measured frequency response function techniques. The passive and active transmission loss of the module was measured using a plane-wave tube. Transmission loss of broadband random-noise in excess of 50 dB was achieved between 100 Hz and 2 kHz. The experimental transmission loss results validated the numerical model and showcased the transmission loss performance of the new module design.
3

Regina Cœli : les images de la Vierge et le culte des reliques : tableaux-reliquaires polonais à l’époque médiévale / Regina Cœli : the images of the Virgin Mary and the cult of relics : polish picture-reliquaries of the Middle Ages / Regina Cœli : die Darstellungen der Muttergottes und der Kult der Reliquien : polnischen Reliquien-Bilder vom Mittelal

Migdal, Anna 14 June 2010 (has links)
Le corpus d’œuvres et la synthèse des études menées sur les images de dévotion à l’époque médiévale n’ont jamais approfondi, dans le contexte européen, la question des peintures mariales ayant fonction de porte-reliques. Le modèle de tableau-reliquaire : panneau unique, diptyque et triptyque comprenant le portrait de la Vierge à l’Enfant peint sur bois (plus rarement sur verre églomisé) enchâssé dans un large cadre incrusté de reliques (parfois de pierres précieuses) se répandit particulièrement sur le territoire de la Petite-Pologne à partir des environs de 1420. Les reliquaires polonais, connus jusqu’au début du XVIe siècle, doivent sans doute être considérés comme une adaptation des types iconiques et formels de provenance byzantine, lesquels furent réinterprétés dans la peinture du Trecento italien. Il s’agit notamment du modèle siennois de retable portatif marial popularisé dès les années 1330-1340. D’après l’étude comparative des œuvres, relative à leurs caractéristiques similaires et leur ancienneté, on envisage l’arrivée d’un tel concept formel en Pologne soit directement de l’Italie, soit par l’intermédiaire de la Bohême.L’expansion des tableaux-reliquaires, typiques de l’art toscan, s’inscrivit au XVe siècle en Europe centrale dans le mouvement général du renouveau de piété, qu’était la devotio moderna. De sorte qu’à côté des représentations singulières, spécialement vénérées au cours des offices liturgiques et paraliturgiques, on voit se répandre des reliquaires moins coûteux dans l’espace privé. Appréciés dans l’intimité des couvents – franciscains et dominicains –, ainsi que dans celle du quotidien des laïcs, ils étaient utilisés comme des autels domestiques ou bien comme des autels pliables de voyage. Ces images d’affection religieuse constituent un phénomène artistique du bas Moyen Âge. Et, quelques-uns des reliquaires semblables connus postérieurement n’assurent pas une véritable continuité de l’ancien modèle à l’époque moderne. / Scholarly investigation of devotional images from the medieval period has never explored, in a European context, the question of Marian paintings functioning as portable relics. The model of the « picture-reliquary » : a single, diptych, or triptych panel comprsing the por-trait of the Virgin and Child painted on wood (or, more rarely, on gilded glass, verre églomisé) set in a large framework encrusted with relics (occasionally with precious stones) was particularly widespread in the territory of Little Poland from c. 1420. Polish reliquaries, known until the beginning of the 16th century, should be considered as an adaptation of iconic types and forms of Byzantine provenance, which were reinterpreted in the painting of the Italian Trecento. Of particular note is the Siennese model of the portable Marian altar piece made popular from the 1330s-40s. From the comparative study of the works, concerning their similarities and their antiquity, one envisages the advent of such a formal concept in Poland either directly from Italy, or by the intermediary of Bohemia.The diffusion of picture-reliquaries, typical of Tuscan art, forms part of the general movement toward a renewal of piety in central Europe in the 15th century, the devotio moderna. As a result, alongside singular representations, especially venerated in the course of liturgical or paraliturgical offices, one sees less costly reliquaries spread in private space. Appreciated in the intimate setting of convents – Franciscan and Dominican – as well as that of the daily life of the laity, these relics were used as domestic altars or as folding altars for travel. These images of religious affection constitute an artistic phenomenon of the late Middle Ages. And, several similar reliquaries known later do not guarantee a veritable continuity of the ancient model to the modern era. / Die erhaltenen Überblicksdarstellungen und Spezialuntersuchungen zu den Frömmigkeitsbildern des Mittelalters haben sich niemals – im europäischen Kontext – mit der Frage derjenigen Mariendarstellungen auseinandergesetzt, die die Funktion von Tragereliquien inne hatten. Das Modell des Reliquien-Bildes – einfaches Tafel-bild, Diptychon oder Triptychon mit einer Darstellung der Jungfrau mit dem Kind, gemalt auf Holz (seltener auf Glas), umschlossen von einem breiten Rahmen, in den Reliquien (mitunter auch Edelsteine) eingefügt sind – verbreitet sich ca. ab 1420 ins-besondere auf dem Gebiet Kleinpolens. Diese polnischen Reliquiare, bekannt bis zum Beginn des 16. Jahrhunderts, können ohne Zweifel als Adaptation ikonischer und formaler Typen byzantinischer Provenienz angesehen werden, die in der Malerei des italienischen Trecento wiederinterpretiert wurden. Dabei handelt es sich vor allem um das Sieneser Model des marianischen Tragaltars, verbreitet seit den Jahren 1330-1340. Folgt man den vergleichenden Untersuchungen der erhaltenen Stücke mit Blick auf ihre übereinstimmenden Charakteristika und ihr Alter, wird das Auf-greifen eines solchen formalen Konzepts in Polen entweder direkt aus Italien oder indirekt über Böhmen wahrscheinlich.Die Ausbreitung dieser Tafel-Reliquiare, typisch für die toskanische Kunst, verbindet sich im 15. Jahrhundert in Mitteleuropa mit der umfassenden Bewegung einer Er-neuerung der Frömmigkeit, bekannt auch unter dem Namen devotio moderna. Dies führt dazu, daß neben einzelnen, vor allem im Rahmen liturgischer oder paraliturgi-scher Veranstaltungen verehrten Darstellungen, zunehmend weniger kostspielige Reliquiare auch in den privaten Raum vordringen. Gehütet sowohl in der Intimität der Klöster – franziskanisch und dominikanisch – als auch im täglichen Lebensraum der Laien, wurden sie als Hausaltäre oder auch als zusammenklappbare Reisealtäre verwendet. Diese Darstellungen religiösen Affekts stellen ein künstlerisches Phäno-men des Spätmittelalters dar. Einige der ähnlichen, allerdings später entstandenen Reliquiare garantieren allerdings keine überzeugende Kontinuität vom alten Modell hin zur Neuzeit.

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