Die Bildpracht spätmittelalterlicher Schnitzretabel zeigte sich zeitgenössischen Betrachtern kaum in der uns heute bekannten Form. In durch Buntglasfenster abgedunkelten Kirchenräumen und hinter einem sichteinschränkenden Lettner verborgen, wurden jene komplexen Bildsysteme mehr erahnt und empfunden als in Gänze gesehen und erfasst. Umso erstaunlicher, dass die kunsthistorische Forschung bisher auf ikonographisch-programmatische Analysen fokussierte, die vor dem Hintergrund ebendieser Rezeption unzureichend sind. Im Dissertationsprojekt werden erstmals kontextgebundene Fragen der Liturgien mit medienästhetischen Erkenntnissen einer bildwissenschaftlich orientierten Forschung verbunden. Diese Verknüpfung bietet die Chance, funktionale und ästhetische Aspekte der Retabel gleichermassen zur Sprache zu bringen. Im Fokus steht die Frage, wie und unter welchen Umständen Hochaltarretabel im Spätmittelalter Sichtbarkeit generieren konnten. Erst unter diesem Gesichtspunkt lässt sich das Potential erfassen, mit welchem sich Retabel zu bestimmten Zeiten in bestimmten räumlichen und liturgischen Zusammenhängen gezeigt haben. Als zentrales Moment kann in diesem Zusammenhang der Lettner identifiziert werden, der Blicke dauerhaft lenkte und zeitweilig restringierte. Im spätmittelalterlichen Kirchenraum, so der Ansatz, ist von graduellen Sichtbarkeiten auszugehen. Im Zentrum des Projektes steht daher die Erforschung der Interferenzen von Retabel, Lettner und umgebendem Raum, die massgeblich auf die Formung und die Wahrnehmung der Retabel zurückwirkten. Im Ergenis weitet sich der Blick auf die gesamte Ausstattung der Kirchenräume, deren soziale Segmentierung und der Deutungsmacht eben jener durch Akteure, welche wiederum durch ihre Interpretationen auf die Folgeausstattungen zurückwirkten. Diese derart akkumulierten Kirchenräume sind machtvoll, kontrollieren Blicke, geben Einblicke, öffnen sich zeitlich reglementiert und changieren so zwischen Sichtbarkeit und Unsichtbarkeit. / The pictorial splendor of late medieval carved altarpieces was rarely revealed to contemporary viewers in the form we are familiar with today. In church interiors darkened by stained glass windows and hidden behind a rood screen that restricted the view, these complex pictorial systems were more sensed and perceived than seen and grasped in their entirety. This makes it all the more astonishing that art historical research has so far focused on iconographic and programmatic analyses, which are inadequate against the background of this very reception. The dissertation project is the first to combine context-bound questions of liturgies with media-aesthetic findings from image-based research. This combination offers the opportunity to address functional and aesthetic aspects of the reredos in equal measure. The focus is on the question of how and under what circumstances high altar retables were able to generate visibility in the late Middle Ages. Only from this point of view is it possible to grasp the potential with which retables appeared at certain times in certain spatial and liturgical contexts. In this context, the rood screen can be identified as a central element that permanently directed and temporarily restricted the gaze. In the late medieval church space, according to the approach, gradual visibilities can be assumed. The project therefore focuses on researching the interferences between the retable, the rood screen and the surrounding space, which had a significant impact on the shaping and perception of the retable. The result is a broader view of the entire decoration of the church interiors, their social segmentation and the power of interpretation of these by actors, who in turn influenced the subsequent decoration through their interpretations. These church spaces accumulated in this way are powerful, control views, provide insights, open up in a temporally regulated manner and thus oscillate between visibility and invisibility.

Spatial impression in both concert halls and reproduced sound has been identified as an important attribute of the listening experience. In this study, the synthesis and objective measurement of spatial impression in reproduced sound is examined. A novel, multichannel spatializing technique for musical synthesis has been developed that entailed the separation of the individual harmonics of a musical note that were spatially distributed over multichannel surround systems. Subjective testing of the techniques revealed that the perceived degree of spatial impression significantly increased as the angular spread of harmonics increased, however, extending the spatial spread beyond 90° did not significantly increase the perception of spatial impression. The concert hall measure of spatial impression, the interaural cross correlation coefficient (IACC) was used to objectively measure the effects of the spatializing techniques. The IACC measurements displayed a strong correlation to the subjective results. Further examination of the IACC measurement indicated the possibility of it’s adaptation to multichannel surround sound in general. A method of adapting IACC to reproduced sound was further developed that involved comparing IACC measurements taken in a concert hall to IACC measurements taken in reproduced versions of the same concert hall. The method was first conducted as a simulation using basic auralisation techniques. Real concert hall measurements and reproduction systems were then employed. Results showed that the method was able to discriminate between the spatial capabilities of a number of different surround sound systems and rank them in a predictable order. The results were further validated by means of a subjective test. In an attempt to sensitise the IACC measurement, the frequency dependency of IACC was investigated by means of a subjective test. The results indicated that a perceptually more accurate indication of spatial impression may be gained by applying a frequency-dependent weighting to IACC measurements. This may be useful in the spatial measurement of both reproduced sound and concert halls.

This thesis will explore a theology of place and placemaking that is focused on the participatory role of humans in both creation and redemption, while suggesting the central and paradigmatic role of artistry in our construction of and identification with place. Building on the most recent theological and philosophical engagement with place, this thesis will argue for a theology of place that takes seriously the doctrines of creation and incarnation, focusing on a particularly redemptive understanding of placemaking in the material world. In its study of scripture and theology, it will focus on God's blessing of people to participate in the making of places, along with the role this human making has in relationship to divine presence and the divine plan for creation and redemption. After developing a theology of place and placemaking more generally, the second half of this thesis will consider the practical, constructive, and transformative capabilities of placemaking as witnessed through the arts. Relying on theological engagement with the arts, it will argue that artistic making of all kinds and attention to place go hand in hand. Exploring a selection of artistic genres, including the photography of Marlene Creates, the quilts of Gee's Bend, and the literature of Wendell Berry, this thesis will suggest that imaginative and “artistic” placemaking practices can give us a deeper understanding of the creative, redemptive, and transformative work of Christ in Creation, while also elucidating our calling to participate in it.

La recherche présentée dans cette thèse a pour objet les producteurs d'images dans l'Éthiopie chrétienne orthodoxe contemporaine et la manière dont ils sont perçus. Ce travail s'inscrit à la croisée de l'anthropologie de la religion, de l'image et de la morale. J'argumenterai que les images servent d'articulation à un réseau de rapports sociaux complexes et qu'elles deviennent en retour les objets d'un discours moral ambivalent. Leur dimension spirituelle place leurs producteurs au cœur d'un tissu d'interactions avec le visible, l'invisible, le matériel et l'immatériel. L'étude des images et de leur production nécessite ainsi un examen du contexte social qui- nous le verrons- à la fois les condamne, les dissimule et leur donne leur sens. Le terrain de cette recherche est réduit à deux types de producteurs d'image : le peintre de l'EOTC (l'Église chrétienne orthodoxe éthiopienne) et le créateur d'images talismaniques appelé debtera. Je soutiendrai que si ce dernier est particulièrement l'objet d'un discours moral ambivalent, c'est avant tout que les images qu'il produit entrent en relation avec le domaine du spirituel dans le but de traiter les souffrances physiques et les problèmes liés à des affects comme la jalousie, la haine et certains désirs. Les affects dont il est question ici ont en commun d'être moralement condamnés et exclus du domaine de l'Église. Je soutiendrai que ces affects particuliers nécessitent un objet- ici, le talisman- pour pouvoir être exprimés. Enfin, dans cette recherche, l'étude des rapports complexes entretenus avec l'objet-médiateur, d'une part, et son producteur, d'autre part, se fera à travers l'examen d'une donnée particulière : le « gossip », c'est-à-dire l'ensemble des discussions informelles, ragots, opinions partagés et exprimés spontanément. / This dissertation is a study of Orthodox image-producers and how they are perceived in Ethiopia today. Its central thesis is that the image-producer creates objects that not only mediate relationships and exercise social power or agency, but also have the capacity to incite a moral discourse. Images in this context can have a spiritual impact that entangles their producers in a web of relationships with the visible, invisible; the material and immaterial: they necessitate an examination of the social agency that defines and obscures them. The focus of this study is restricted to two types of image-producer: the Ethiopian Orthodox Tewahedo Church painter and the creator of talismanic images (known as a debtera). I argue that the debtera is perceived to be more morally problematic than the church painter because his images are intended to interact in the spiritual realm to treat certain forms of physical and emotional suffering. The kinds of emotions that a talismanic image treats however are "socially reprehensible" (eschewed by official Church doctrine, and as such condemned morally) as are those who interact with these emotions through image production- the debtera. I situate this thesis at the crossroads of the anthropology of religion, imagery and morality. Here, personhood, relationships and the dialogue between materiality and immateriality must be taken into account. This dissertation's intent is to articulate some of the nuances in object-mediated social relations that are made apparent through gossip. I stipulate that, in this culture, certain officially proscribed emotions require objects (such as the talismanic images) to be expressed. As a consequence of this proscription, the image-producer responsible for the creation of that object is subject to moral opprobrium. In a sense, given the full range of human conduct and emotions, the strict limits that the Ethiopian Orthodox Tewahedo Church places on what is acceptable in these realms creates a vacuum in which the proscribed conduct and emotions must be expressed in the shadows of the Church. And because of the particular importance this culture places on the image as the instrument that acts in these domains, the debtera and the talisman achieve a centrality that rivals that of the Church-sanctioned image producers.

Representations of the Holy Trinity have increasingly come under scrutiny, exposing two competing paradigms at opposite ends of the theological spectrum: the legitimacy and the illegitimacy of imaging the Triune God with focus on the invisible Father who was imaged as an individual from Late Antiquity and beyond. An overview of these two conflicting views has unveiled a number of inconsistencies in how the Early Christian iconography of God the Father and the Trinity has been interpreted. This thesis provides a unique re-evaluation of the surviving Trinitarian visual material between c.300 to c.730. Primarily, this study collates pictorial evidence preserved in the mediums of sarcophagi, catacomb frescoes, mosaics, illuminated manuscripts and an icon that depicts Divinity. It proceeds to critique modern misconceptions of the identity, form, meaning, function and reception of the depictions. The thesis traces the visual shift amid overt and covert images of Divinity by decoding important artworks such as the Ashburnham Pentateuch and the Codex Amiatinus; Christians visualised explicitly the ' invisibility' of God but created an unprecedented invention, the depiction of the Father through Christ's image. The innovative depiction heralded future visual formulas of Divinity echoing the complexities of Trinitarian material culture of the Mediterranean world.

In this study, a mathematical model is developed for investigating the discrete sound propagation in viscoelastic medium to identify its viscoelastic properties. The outcome of the model suggests that pulse repetition frequency is a very important parameter for the determination of relaxation time. Adjusting the order of magnitude of the pulse repetition frequency, the corresponding relaxation time which has similar magnitude with pulse repetition frequency is filtered while the others in the spectrum are discarded. Discrete relaxation spectrum can be obtained by changing the magnitude of the pulse repetition frequency. Therefore, the model enables to characterize the relaxation times by ultrasonic measurements.

Several methods are developed to measure absorption and scattering coefficients of materials. In this study, a new method based on cepstral deconvolution technique is proposed. A reverberation room method standardized recently by ISO (ISO 17497-1) is taken as the reference for measurements. Several measurements were conducted in a physically scaled reverberation room and results are evaluated according to these two methods, namely, the method given in the standard and cepstral deconvolution method. Two methods differ from each other in the estimation of specular parts of room impulse responses essential for determination of scattering coefficients. In the standard method, specular part is found by synchronous averaging of impulse responses. However, cepstral deconvolution method utilizes cepstral analysis to obtain the specular part instead of averaging. Results obtained by both of these two approaches are compared for five different test materials. Both of the methods gave almost same values for absorption coefficients. On the other hand, lower scattering coefficient values have been obtained for cepstral deconvolution with respect to the ISO method.

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Non-invasive and fast flow measurement techniques have had increasing importance for the last decades. Scientists are looking for such quick techniques to be able to monitor real velocities without disturbing flow itself. Ultrasound Doppler velocimetry (UDV) being one of such techniques promising with advantages of getting simultaneous velocity measurements from several points and of applicability for opaque liquids as well. UDV is a technique which is still being developed for new applications and analysis of complex flows. In this study effect of sinusoidal oscillating, turbulent (random) and viscoelastic fluid motions on UDV signals were investigated theoretically and experimentally. Obtained mathematical relations for random and viscoelastic motions were utilized to get statistics of flow and distribution of relaxation spectrum, respectively. Analytical analysis and numerical simulation of sinusoidal oscillating flow depicted that there is a critical value for the ratio of oscillation amplitude to oscillation frequency for a specified set of measurement parameters of UDV. Above this critical value UDV is not successful to determine mean flow velocity. Mathematical relations between velocity probability density function (PDF) &ndash / velocity auto correlation function (ACF) and UDV signal spectrum were obtained in the analysis v of flow with random velocity. Comparison of velocity ACFs from direct velocity measurements and from raw in-phase (I) and quadrature (Q) signals through derived relation, revealed that time resolution of UDV technique is not enough for getting a good velocity ACF and thus turbulence spectrum. Using I and Q signals rather than measured velocities to get velocity ACF, increased the time resolution in the order of number of pulses used for getting one velocity value (Nprn). Velocity PDF obtained from UDV spectrum was compared with the one obtained from measured velocities with the assumption of Gaussian PDF. Both velocity PDFs were consistent. Also some parameters of pipe turbulence from literature were compared with the presented findings from velocity ACF obtained from I and Q signals through derived relation. Results showed good compatibility. In the last part of the study, complex viscosity of a linear viscoelastic fluid mathematically related to spectrum of UDV for a pipe flow with small-amplitude oscillating pressure field. Generalized Maxwell model was employed to express complex viscosity terms. Zero frequency (mean flow) component of UDV spectrum was used to obtain an equation for relaxation viscosities of generalized Maxwell model. Results have revealed that UDV technique can also be used to probe some of viscoelastic material functions. In conclusion, UDV is relatively new but a promising technique for the measurement and analysis of complex flows in a non-invasive manner.