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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.
81

The political potentials of visual technology: a postmodern perspective

Yue, Wai-chik, Jack., 余偉職. January 2011 (has links)
published_or_final_version / Education / Doctoral / Doctor of Education
82

Acoustic measurements of flowing and quasi-static particulate suspensions

Moss, Simon H. O. January 1997 (has links)
Flowing suspensions of solid particles in gas can be found in various industrial applications, as a method for transporting powdered solids (known as "pneumatic conveying"). The problem of measuring the mass concentration of the solid fraction has not yet been satisfactorily resolved. This thesis explores acoustic techniques to measure the particle concentration. Controlled suspensions -- both flowing and quasi-static - were generated in cylindrical tubes, and their acoustic properties were measured over three frequency ranges, requiring a variety of different measuring techniques: Plane wave region (200 -4 kHz): the attenuation of plane waves travelling along the flow tube was measured. A simple method of measuring the characteristic impedance of the suspension was also devised and preliminary measurements were made. Reverberant region (4 - 20 kHz). Three parameters were measured: the decay rate of the reverberant field in certain frequency bands; the level of actively-excited steady state sound; and the frequency of transverse resonant modes of the pipe. Ultrasonic region (40 - 75 kHz): the attenuation of ultrasound was measured across the pipe diameter. The measurements were compared with theoretical predictions. They showed the predicted linearity of acoustic attenuation with concentration, although the frequency dependence was less well predicted. In general, the larger particle sizes produced the greatest discrepancy; an explanation is proposed. Ultrasonic measurements showed significant differences from the predicted frequency dependence. A method of isolating acoustic transducers from the flow with a column of clean air is described. However, measurements may be complicated by interactions at the orifice into the flow pipe. Further work is needed in this area. It is concluded that acoustic methods could be used to measure particle concentration. However, to remain insensitive to changes in the properties of the particles - size in particular - measurements must be made at more than one frequency.
83

The design and construction of quintuple amplifier by synthesis of feed-back pairs

Clark, Clayton Joseph, 1914- January 1957 (has links)
No description available.
84

The Influence of Modality Combinations on Communication in Collaborative Virtual Environments

Moll, Jonas January 2013 (has links)
Although many studies have been performed on collaboration in multimodal interfaces not many of these have looked specifically on how the supported modalities influence the task solving strategies chosen and the communication between users solving a joint task in collaborative virtual environments. Therefore, the thesis studies performed aimed at shedding light on these aspects of multimodality. The specific research question studied is: How do changes in modality combinations influence employed work strategies, communication during task solving and the task efficiency in collaborative multimodal virtual environments? The studies performed build on theories from HCI, CSCW, human perception and mediated communication and are thus inter-disciplinary in nature. A variety of cases have been studied; collaboration between sighted and visually impaired, task solving in visually demanding environments and to some extent support for achieving medical diagnoses. The research presented in this thesis began with a field study in elementary schools, focusing on collaboration between visually impaired and sighted pupils. The shared environment was in this case a virtual room in which objects could be moved around by means of haptic devices. The results showed a great potential for haptic feedback when it came to supporting collaboration and most of all communication between the participants. A lack of awareness information about mostly the sighted pupils’ actions laid the ground for a follow-up study in which sighted and blindfolded students solved tasks in the same interface. A formal experiment was carried out in this case, comparing a visual/haptic environment with a visual/haptic/audio environment. Results showed that the addition of audio feedback to the visual/haptic environment was beneficial in many respects. Up until now, the focus had been entirely on collaboration between sighted persons and those who cannot see. This is why the next experimental study, based on an abstract gaming environment, aimed at collaboration between sighted persons. Since the earlier studies showed that the combination of modalities clearly matter, this new experiment compared three modality combinations – visual/haptic, visual/audio and visual/haptic/audio. Once again, the results clearly showed that the combination of modalities has an effect on task performance and that it influences collaboration and communication in particular. All studies performed have been subject to both quantitative analysis of performance measures and qualitative analysis of dialogues between collaborators. Even though quantitative data on task performance has played an important role, the main focus has been on qualitative data in all studies performed. The results show that different combinations of modalities influence the collaboration and in particular the communication between two participants solving tasks in different ways in a number of multimodal interfaces. In all cases in which a visual/haptic/audio condition has been compared to a visual/haptic or a visual/audio condition the performance was significantly better in the visual/haptic/audio condition. One of the most important conclusions drawn from the qualitative analysis of dialogues is that both haptic and audio feedback can have communicative properties which influence the dialogue and as a consequence the collaboration. / <p>QC 20131108</p>
85

Design and analysis of fixed and adaptive sigma-delta modulators

Yu, Jie January 1992 (has links)
No description available.
86

Content based retrieval and navigation of music using melodic pitch contours

Blackburn, Steven George January 2000 (has links)
No description available.
87

The relative effects of audio-visual vs. audio-only lecture presentation on retention and evaluation.

Katz, James Harold. January 1969 (has links)
No description available.
88

Multimedia presentations in nutrition : college students' attitudes and perceptions /

Brooks, Lisa. January 1997 (has links) (PDF)
Thesis (M.S.)--Eastern Illinois University, 1997. / Includes bibliographical references (leaves 50-54).
89

The effectiveness of dramatized recordings in religious education

Pfaff, Rosemary, January 1951 (has links)
Thesis--Johns Hopkins University. / Vita. Bibliography: p. 84-86.
90

The effectiveness of dramatized recordings in religious education

Pfaff, Rosemary, January 1951 (has links)
Thesis--Johns Hopkins University. / Vita. Bibliography: p. 84-86.

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