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Full-Text Articles in Engineering
Self-Enhancement Of Dynamic Gratings In Photogalvanic Crystals, Nickolai Kukhtarev, Sergei F. Lyuksyutov, Preben Buchhave, Tatiana Kukhtareva, K. Sayano, Partha P. Banerjee
Self-Enhancement Of Dynamic Gratings In Photogalvanic Crystals, Nickolai Kukhtarev, Sergei F. Lyuksyutov, Preben Buchhave, Tatiana Kukhtareva, K. Sayano, Partha P. Banerjee
Electrical and Computer Engineering Faculty Publications
We have developed a compact closed-form solution of the band transport model for high-contrast gratings in photogalvanic crystals. Our solution predicts the effect of the photoconductivity and the electric field grating enhancement due to the photogalvanic effect. We predict a pronounced dependence of the steady-state photogalvanic current on the contrast of the interference pattern and an increase of holographic storage time due to the enhancement of the photoconductivity grating contrast. In the high contrast limit and a large photogalvanic effect the refractive index grating will be shifted from the position of the intensity modulation pattern, contrary to the usually adopted …
Design Methodology For Low Speed High Altitude Long Endurance Unmanned Aerial Vehicles, Aaron Altman
Design Methodology For Low Speed High Altitude Long Endurance Unmanned Aerial Vehicles, Aaron Altman
Mechanical and Aerospace Engineering Faculty Publications
High Altitude Long Endurance (HALE) Unmanned Aerial Vehicles (UAV's) are increasingly being considered to perform a wide range of tasks. Recent years have seen greater value of UAV's in the military reconnaissance arena, first in the Persian Gulf war, with the use of small UAV's, and more recently over Bosnia with medium sized UAV's.
The NASA ERAST program uses HALE UAV's for environmental sensing and monitoring. The military has investigated using HALE UAV's for Theater Ballistic Missile defense, as well as general battlefield reconnaissance. Proposals have been made to use HALE UAV's for communications relay, long term surveillance (with a …
Experimental Investigations Of Wavelength And Angular Errors In Holographic Gratings With Non-Bragg-Matched Read Beams, Monish Ranjan Chatterjee, Vivek Ray
Experimental Investigations Of Wavelength And Angular Errors In Holographic Gratings With Non-Bragg-Matched Read Beams, Monish Ranjan Chatterjee, Vivek Ray
Electrical and Computer Engineering Faculty Publications
Perfect Bragg matching is generally desirable for accurate optical interconnections with holographic gratings. In reality, however, gratings may be illuminated by READ beams with non-Bragg-matched angles, or wavelengths, or both. In such cases, the scattered beams are generally misdirected, and may suffer loss of efficiency and possibly more serious errors such as crosstalk noise or missed connections. A conventional wave-vector triad method of analyzing the scattered beam errors leads readily to near-Bragg estimates of the output angular misalignment. However, the READ wave-vector triads appear to indicate a possible wavelength shift in the output beam even with a Bragg-matched READ wavelength, …
Joint Wavelet Transform Correlation With Separated Target And Reference Planes, Boon Yi Soon, Mohammad A. Karim, Russell C. Hardie, Mohammad S. Alam
Joint Wavelet Transform Correlation With Separated Target And Reference Planes, Boon Yi Soon, Mohammad A. Karim, Russell C. Hardie, Mohammad S. Alam
Electrical and Computer Engineering Faculty Publications
In recent years, we realize the usefulness of feature extraction for optical correlator and hereby, we investigate the capability of Laplace operator in feature extraction of multiple targets. The first-order terms and the false alarm terms in the correlation output would be removed using electronic power spectrum subtraction technique. Most importantly, the entire magneto-optic SLM is completely utilized for displaying only targets in the input scene. A new cost efficient hardware implementation is proposed and aforementioned result of the proposed system is evaluated through computer simulation.
High-Resolution Image Reconstruction From A Sequence Of Rotated And Translated Frames And Its Application To An Infrared Imaging System, Russell C. Hardie, Kenneth J. Barnard, John G. Bognar, Ernest E. Armstrong, Edward A. Watson
High-Resolution Image Reconstruction From A Sequence Of Rotated And Translated Frames And Its Application To An Infrared Imaging System, Russell C. Hardie, Kenneth J. Barnard, John G. Bognar, Ernest E. Armstrong, Edward A. Watson
Electrical and Computer Engineering Faculty Publications
Some imaging systems employ detector arrays that are not sufficiently dense to meet the Nyquist criterion during image acquisition. This is particularly true for many staring infrared imagers. Thus, the full resolution afforded by the optics is not being realized in such a system. This paper presents a technique for estimating a high-resolution image, with reduced aliasing, from a sequence of undersampled rotated and translationally shifted frames. Such an image sequence can be obtained if an imager is mounted on a moving platform, such as an aircraft. Several approaches to this type of problem have been proposed in the literature. …
Attitude Measurement, Mark A. Stedham, Partha P. Banerjee, Seiji Nishifuji, Shogo Tanaka
Attitude Measurement, Mark A. Stedham, Partha P. Banerjee, Seiji Nishifuji, Shogo Tanaka
Electrical and Computer Engineering Faculty Publications
In many practical situations, it is important to determine and measure the attitude of a particular vehicle, such as a ship, an airplane, a piece of mechanical equipment such as a, crane lifter, or a spacecraft. For this reason, many attitude sensors have been developed with advanced computer and semiconductor technologies. This section first introduces the various attitude sensors with an explanation of their operating principles and then presents several methodologies for attitude measurement and determination, including ships and crane lifters, aircraft, and spacecraft applications.
A Study Of The Fundamental Operations Of A Capillary Driven Heat Transfer Device In Both Normal And Low Gravity Part 1-Liquid Slug Formation In Low Gravity, Jeffrey S. Allen, Kevin P. Hallinan, Jack Lekan
A Study Of The Fundamental Operations Of A Capillary Driven Heat Transfer Device In Both Normal And Low Gravity Part 1-Liquid Slug Formation In Low Gravity, Jeffrey S. Allen, Kevin P. Hallinan, Jack Lekan
Mechanical and Aerospace Engineering Faculty Publications
Research has been conducted to observe the operation of a capillary pumped loop (CPL) in both normal and low gravity environments in order to ascertain the causes of device failure. The failures of capillary pumped heat transport devices in low gravity; specifically; evaporator dryout, are not understood and the available data for analyzing the failures is incomplete.
To observe failure in these devices an idealized experimental CPL was configured for testing in both a normal-gravity and a low-gravity environment. The experimental test loop was constructed completely of Pyrex tubing to allow for visualization of system operations. Heat was added to …