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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.
411

A Simple Package Technique of Light Emitting Diode for Enhancing Illuminant Quality

Lin, Yu-Chung 20 June 2008 (has links)
The purpose of this thesis is to fabricate an LED module with low half intensity angle(HIA) ,and to use this module to form a line source with optical performance comparable to that of a CCFL .In addition ,heat dissipation of the LED module on different sub-mounts is also investigated . The LED modules were formed by first etching a through si via on silicon substrate using wet etching technology for light confining .Then a thin layer of metal was deposited on to the via to reflect the lights emitted from the LED .The LED die was attached to the Si sub-mount with electrodes ,and the connections between the LED and the Si sub-mount were completed by wire bonding .Finally ,the LED modules were obtained by positioning the Si substrates onto the Si sub-mounts using UV epoxy . The optical performance of the LED module was simulated by Lighttools .For the si substrate with a thickness of 400 £gm ,a simulated HIA of 36 o was obtained .Using six-LED package ,a 3-cm line source with 84.8% output uniformity was simulated .On the other hand ,the measured HIA of a LED module ,and the uniformity of 3-cm line source are 38 o and 84.8% ,respectively. The thermal resistance of the si sub-mounts were also investigated .The different structures of the sub-mount were proposed ,namely ,LED to Copper case ,LED to Si sub-mount to Copper case ,and LED to Si sub-mount with Copper filled via to Copper case .The estimated thermal resistance of the sub-mounts are 13 W/mk¡B19.4 W/mk and 34.7 W/mk .We believe that the large thermal resistance of the Si sub-mount with Copper filled via is primarily caused by 800 £gm thick substrate .
412

Electromagnetic Fields in Moving and Inhomogeneous Media

Piwnicki, Paul January 2001 (has links)
<p>The present thesis deals with electromagnetic effectscreated by the motion or inhomogeneity of a dielectricmedium.In the first paper the quantum R\"ontgen effect isdiscussed. Here a rotating Bose-Einstein condensate -- oranother kind of quantum fluid -- is placed in a chargedcapacitor. The medium's rotation creates a magnetic field.Quantum media can only rotate in form of vortices, which leadsto a magnetic field corresponding to the field of a magneticmonopole. In the remaining part of the thesis the geometricalrepresentation of electromagnetic fields in moving andinhomogeneous media is discussed. It is shown that aninhomogeneously moving dielectric, e.g., a vortex, defines aspace-time metric and light rays follow null-geodesics definedby this metric. This means that light propagation in a movingmedium is analogous to light propagation in a gravitationalfield. The possibility of creating laboratory models ofastronomical objects, e.g., black holes is discussed. Theapplicability of the newly developed media with extremely lowgroup velocity for the actual creation of such an experiment isconsidered. Furthermore, a model for the case of the slowlymoving medium is discussed. Here the light propagation isanalogous to the motion of a charged particle propagatingthrough a magnetic field. The velocity of the flow correspondsto the vector potential. Consequently, light propagation in avortex corresponds to the Aharonov-Bohm effect. Finally, acomplete geometrical description of light in an inhomogeneousdielectric at rest is presented. It is shown that lighttrajectories are geodesics of a three-dimensional metricdefined by the medium. Here even the propagation of the fieldsis discussed in the language of differential geometry and it isshown that the field vectors are parallel transported along therays. These considerations can be generalized to thefour-dimensional case where the field-strength tensor isparallel transported along the ray. This emphasizes thefar-reaching analogy between light in moving media and light ingravitational fields.</p>
413

Des effets chimiques et électriques produits sous l'influence de la lumière solaire thèse de physique présentée et soutenue à la Faculté des sciences de Paris le août 1840 /

Becquerel, Edmond January 1900 (has links)
Thèse : Physique : Paris, Faculté des sciences : 1840. / Titre provenant de l'écran-titre. Références bibliogr.
414

Winter seasonal affective disorder epidemiological evidence for the light-deprivation hypothesis /

Woodson, Harrell Wesley. January 2003 (has links)
Thesis (Ph. D.)--University of Texas at Austin, 2003. / Vita. Includes bibliographical references. Available also from UMI Company.
415

Synthesis of luminophoric disubstituted polyacetylenes and fabrications of efficient, stable, blue light-emitting diodes /

Xie, Zhiliang. January 2003 (has links)
Thesis (Ph. D.)--Hong Kong University of Science and Technology, 2003. / Includes bibliographical references (leaves 255-278). Also available in electronic version. Access restricted to campus users.
416

Laboratory studies of the growth, sublimation, and light-scattering properties of single levitated ice particles /

Bacon, Neil J., January 2001 (has links)
Thesis (Ph. D.)--University of Washington, 2001. / Vita. Includes bibliographical references (p. 122-138).
417

Fabrication and characteristics of the InGaN/GaN multiple quantum well blue LEDs /

Liang, Hu. January 2003 (has links)
Thesis (M. Phil.)--Hong Kong University of Science and Technology, 2003. / Includes bibliographical references (leaves 62-66). Also available in electronic version. Access restricted to campus users.
418

Study on materials for organic light-emitting diodes /

Chen, Haiying. January 2003 (has links)
Thesis (Ph.D.)--Hong Kong University of Science and Technology, 2003. / Includes bibliographical references. Also available in electronic version. Access restricted to campus users.
419

Organic light emitting diodes (OLEDs) for lighting /

Yu, Xiaoming. January 2009 (has links)
Includes bibliographical references.
420

Testing and performance characterization of the split field polarimeter in the 3-5m̆ waveband /

Tung, Yan Foo. January 2003 (has links) (PDF)
Thesis (M.S. in Combat Systems Technology)--Naval Postgraduate School, December 2003. / Thesis advisor(s): Alfred W. Cooper, Gamani Karunasiri. Includes bibliographical references (p. 83-84). Also available online.

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