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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.
101

High-permittivity Hemispherical Lens for MIMO Applications with Closely-spaced Antennas

Ho, Alvin 26 November 2013 (has links)
With the rapid adoption and development of new standards, Multiple-Input Multiple-Output (MIMO) technology is becoming a necessity in current wireless systems. One problem posed by using multiple antennas at a transmitter or receiver is the undesirable effect of signal correlation between closely-spaced radiating elements. This thesis presents the concept, design, and evaluation of a hemispherical lens antenna for use in MIMO systems. A high-permittivity dielectric material allows radiating elements to be placed in close proximity with reduced spatial correlation effects. An intermediate matching layer and a hemispherical lens design facilitate the preservation of the pattern characteristics in the transition between the dielectric and free-space. The antenna was simulated against benchmark antenna arrays in free-space and showed a 35%-70% improvement in channel capacity in multipath-rich environments, showing strength as a candidate for further development in MIMO applications.
102

Etorinių kontaktinių lęšių padėties ant akies stabilumo tyrimas / The investigation of toric contact lens position on the eye stability

Tekutienė, Vilma 21 August 2013 (has links)
Koreguoti kliniškai reikšmingą astigmatizmą būtina, nes visai nekoreguotas ar neteisingoje ašyje iškoreguotas astigmatizmas sukelia ne tik blogą matymą, bet ir astenopiją. Koreguoti kliniškai reikšmingą astigmatizmą būtina, nes visai nekoreguotas ar neteisingoje ašyje iškoreguotas astigmatizmas sukelia ne tik blogą matymą, bet astenopiją. Toriniai kontaktiniai lęšiai (TKL) suteikia galimybę labai tiksliai ištaisyti šią ydą, bet viena būtina sąlyga - jie turi būti stabilioje padėtyje. TKL stabilumas priklauso nuo vokų plyšio, ragenos formos, vokų prispaudimo jėgos, o taip pat nuo refrakcijos ydos dydžio ir astigmatizmo ašies. / N Scientific and Technical Progress century eyesight play an increasingly larger burden. To adjust clinically significant astigmatism is necessary, because completely uncorrected or wrong corrected axis of astigmatism cause not only poor vision, but asthenopia. Toric contact lenses (TKL) allows very precise remedy of this defect, but one necessary condition - they must be in a stable position. TKL stability depends on the eye crack opening, corneal shape, eyelid clamping force, as well as the refractive defect size and astigmatism axis.
103

Laser raman spectroscopic studies of ocular lens aging and cataractogenesis

Bergbauer, Katrina L. 12 1900 (has links)
No description available.
104

Characterization of normal aging and cataractous processes in the eye lens by laser raman spectroscopy

Barron, Brent Christian 12 1900 (has links)
No description available.
105

The molecular chaperone α-crystallin protects proteins from UV-induced aggregation

Knight, Grady C. 08 1900 (has links)
No description available.
106

High-permittivity Hemispherical Lens for MIMO Applications with Closely-spaced Antennas

Ho, Alvin 26 November 2013 (has links)
With the rapid adoption and development of new standards, Multiple-Input Multiple-Output (MIMO) technology is becoming a necessity in current wireless systems. One problem posed by using multiple antennas at a transmitter or receiver is the undesirable effect of signal correlation between closely-spaced radiating elements. This thesis presents the concept, design, and evaluation of a hemispherical lens antenna for use in MIMO systems. A high-permittivity dielectric material allows radiating elements to be placed in close proximity with reduced spatial correlation effects. An intermediate matching layer and a hemispherical lens design facilitate the preservation of the pattern characteristics in the transition between the dielectric and free-space. The antenna was simulated against benchmark antenna arrays in free-space and showed a 35%-70% improvement in channel capacity in multipath-rich environments, showing strength as a candidate for further development in MIMO applications.
107

An Aperture Synthesis Technique for Cylindrical Printed Lens/Transmitarray Antennas with Shaped Beams

Biswas, Mahmud 27 June 2013 (has links)
Printed lens antennas offer the possibility of realizing shaped beam patterns using no more complexity than is required for pencil beam patterns. Shaped beam patterns can be obtained by appropriately determining the complex transmission coefficient required for each cell (or element) of the printed lens, taking into account the varying feed field over the input surface of the lens. Certain ranges of transmission coefficient amplitude and phase are undesirable (eg. too low an amplitude implies a large reflection at the lens input surface). It would be preferable to constrain the range of values that the transmission coefficient can take as an integral part of the lens synthesis procedure, and thus the transmission coefficient itself needs to be the synthesis variable. In this thesis a synthesis technique for doing this is developed based on the method of generalized projections, modified to “operate” in the space of transmission coefficients. This makes it possible to immediately perceive what influence constraints on the actual transmission coefficients have on the possible radiation pattern performance. In addition, an approach that allows one to constrain the transmission coefficient to values that must be selected from an available database of transmission coefficients is incorporated into the synthesis technique.
108

A simple method of the electric/magnetic field observation by a conventional transmission electron microscope

Sasaki, Katsuhiro, Saka, Hiroyasu January 2005 (has links)
Pacific Rim International Conference on Advanced Materials and Processing <DA14524950> (5th : 2004 : Beijing, China)
109

Connexin 45.6 in lens development : a dissertation /

Banks, Eric A. January 2007 (has links)
Dissertation (Ph.D.).--University of Texas Graduate School of Biomedical Sciences at San Antonio, 2007. / Vita. Includes bibliographical references.
110

A full electromagnetic analysis of fresnel zone plate antennas and the application to a free-space focused-beammeasurement system

Reid, David R.. January 2008 (has links)
Thesis (Ph.D)--Electrical and Computer Engineering, Georgia Institute of Technology, 2009. / Committee Chair: Glenn S. Smith; Committee Member: Andrew F. Peterson; Committee Member: Gregory D. Durgin; Committee Member: John W. Schultz; Committee Member: Waymond R. Scott, Jr.. Part of the SMARTech Electronic Thesis and Dissertation Collection.

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