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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.
71

REDUCED APERTURE MICROSTRIP ANTENNAS FOR AIRBORNE VEHICLES

Kujiraoka, Scott R., De Vries, James M. 10 1900 (has links)
International Telemetering Conference Proceedings / October 26-29, 1998 / Town & Country Resort Hotel and Convention Center, San Diego, California / The available space for the mounting of antennas on missiles and airborne targets is very limited. The vehicle integrator is constantly striving for smaller antenna apertures while requiring increased performance. Microstrip antennas with moderate dielectric loading have been successfully utilized in the past to meet these requirements. With the advent of high dielectric substrate materials, the designer now has the option of further reducing the size of the antenna while preserving the most desirable performance attributes. An example of the size reduction achievable with the new substrate materials is presented along with performance characteristics.
72

LASER DAMAGE MEASUREMENTS ON ALL-DIELECTRIC NARROW-BAND FILTERS.

DeSandre, Lewis Francis. January 1985 (has links)
No description available.
73

Electrical measurement of sucrose in sugar beet

Miller, Stuart M. January 1995 (has links)
No description available.
74

Characterisation of the solid and solution state properties of drug dispersions in polyethylene glycols

Craig, Duncan Quinnell Mackenzie January 1989 (has links)
No description available.
75

Millimetre wave measurements and device characterisation at 140 GHz

Boese, Ingo January 1998 (has links)
No description available.
76

Electrokinetic and electrostatic properties of highly charged colloids in low-dielectric media

Gillespie, David January 2016 (has links)
No description available.
77

Classical and quantum nonlinear optics in confined photonic structures

Ghafari Banaee, Mohamadreza 05 1900 (has links)
Nonlinear optical phenomena associated with high-order soliton breakup in photonic crystal fibres and squeezed state generation in three dimensional photonic crystal microcavities are investigated. In both cases, the properties of periodically patterned, high-index contrast dielectric structures are engineered to control the dispersion and local field enhancements of the electromagnetic field. Ultra-short pulse propagation in a polarization-maintaining microstructured fibre (with 1 um core diameter and 1.1 m length) is investigated experimentally and theoretically. For an 80 MHz train of 130 fs pulses with average propagating powers in the fibre up to 13.8 mW, the output spectra consist of multiple discrete solitons that shift continuously to lower energies as they propagate in the lowest transverse mode of the fibre. The number of solitons and the amount that they shift both increase with the launched power. All of the data is quantitatively consistent with solutions of the nonlinear Schrodinger equation, but only when the Raman nonlinearity is treated without approximation, and self-steepening is included. The feasibility of using a parametric down-conversion process to generate squeezed electromagnetic states in 3D photonic crystal microcavity structures is investigated for the first time. The spectrum of the squeezed light is theoretically calculated by using an open cavity quantum mechanical formalism. The cavity communicates with two main channels, which model vertical radiation losses and coupling into a single-mode waveguide respectively. The amount of squeezing is determined by the correlation functions relating the field quadratures of light coupled into the waveguide. All of the relevant model parameters are realistically estimated using 3D finite-difference time-domain (FDTD) simulations. Squeezing up to ~20% below the shot noise level is predicted for reasonable optical excitation levels. To preserve the squeezed nature of the light generated in the microcavity, a unidirectional coupling geometry from the microcavity to a ridge waveguide in a slab photonic crystal structure is studied. The structure was successfully fabricated in a silicon membrane, and experimental measurements of the efficiency for the signal coupled out of the structure are in good agreement with the result of FDTD simulations. The coupling efficiency of the cavity mode to the output channel is ~60%.
78

Analysis of dielectric waveguide termination with a slightly tilted facet

Wu, Chao-chin 07 July 2004 (has links)
Utilizing the semiconductor processing technology, a large number of optical components can be integrated into a small area. It is of low cost and high reliability and can be massively produced. The PLC(planar light circuit) has become an important component with the opto-communication industry.In this thesis, we aim to study dielectric waveguide termination witha slightly tilted facet. A waveguide with normal termination in the air will have non-zero reflection coefficients due to the impedance difference at the core-air junction. To reduce the reflection of the fundamental mode, it is custom to terminate the waveguide with a small tilted angle. The angle is optimally chosen to avoid spurious scattering into high-order radiation modes.To analyze this problem, we employ the modal expansion method for both the reflected waves and the transmitted waves. We then analytically extend the waves and join the two fields on the bordering line by matching the fields and their normal derivatives. An incomplete transverse-mode integral equation (TMIE) is derived for the reflection and transmission coefficients. The incomplete TMIE is good for waveguide termination with small tilted angles. Our analysis show that for multi-mode 1-D slab waveguide (simulating the 1-D optical fiber), the fundamental mode reflection coefficient is about -28dB down. It gradually reduces to -60dB as we increase the tilt angle from around 8 degrees. The result agrees well with those calculate from frequency-domain finite-difference method.
79

Analysis of the Current for 161kV XLPE Underground Cable

Chang, Fu-Yuan 30 July 2001 (has links)
Nowadays, the economic grows fast and changes a lot. Meanwhile, the central city gets bigger and bigger. More and more buildings locate everywhere while people enjoy their modern life. The needs of electricity grow by the way. In order to provide more power, the Power Company has tried very hard to find new resources. However, there is another problem when transferring the power through crowded city. To avoid the geographic limitation, most of the overhead lines have been changed into under ground lines instead. Sooner or later, the under ground cable will become the main power transmission. This thesis focuses on the current rating distribution of Taiwan 161KV line with various PE underground cables that contain one circuit, two circuits, four circuits, and eight circuits. The current rating goes within various pipes. To find the best economic benefit with the lowest investment by rearranging the pipes to reach the most current rating and by matching the current rating from under ground cable with the over head cable is the main goal of this thesis. JCS NO.168 analyzes the set up map for all the pipes. In order to offer the best power supply, to maintain the longest cable life within the acceptable working days, the calculating scripts support to figure out the current rating in shortest time.
80

Interface state characterization techniques for MOS capacitors incorporating ultra-thin dielectric films /

Gabrys, Ann M. January 2001 (has links)
Thesis (M.S.)--University of Minnesota, 2001. / "Accompanying CD-ROM contains Excel spreadsheets and Mathematica notebooks that contain data and templates" for further investigation.--P. 68. Includes bibliographical references (leaves 70-71). Also available on the World Wide Web as a PDF file.

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