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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.
191

F-22 versus UCAV fixing today's deficiencies leaves questions about tomorrow's dominance /

Beales, Brian O. January 2009 (has links) (PDF)
Thesis (M.A. in Security Studies (Homeland Security and Defense))--Naval Postgraduate School, December 2009. / Thesis Advisor(s): Looney, Robert E. ; McNab, Robert M. "December 2009." Description based on title screen as viewed on January 27, 2010. Author(s) subject terms: F-22, MQ-1, MQ-9, UCAV, homeland defense, aircraft effectiveness, defense spending, manned flight, unmanned flight. Includes bibliographical references (p. 71-76). Also available in print.
192

Poincaré disc models in hyperbolic geometry

Bouboulis, Anna Marie 12 December 2013 (has links)
This report discusses two examples of the use of Poincare disc models and their different relationships to Euclidean geometry. The topics include light reflection in hyperbolic geometry and the Hyperbolic Pythagorean Theorem; all in relation to the Poincare unit disc and Poincare upper half plane model. / text
193

Terahertz Field Enhancement by Optimized Coupling and Adiabatic Tapering

Smith, Robert Levi 09 September 2014 (has links)
Waveguides are desirable components for energy transmission throughout the electromagnetic spectrum. This thesis experimentally examines a thick slot waveguide for THz guiding and field enhancement. The waveguide is machined from planar copper sheets using the novel technique of femtosecond laser micromachining. In-plane photoconductive THz coupling to a thick slot waveguide is demonstrated using Discontinuous Galerkin Time Domain (DGTD) simulation. The results reveal positive implications for broadband low-loss/dispersion transmission lines up to 1.5 THz. / Graduate / 0544 / 0607 / 0756 / levismith3@hotmail.com
194

Restrictions of Steiner Bundles and Divisors on the Hilbert Scheme of Points in the Plane

Huizenga, Jack 18 September 2012 (has links)
The Hilbert scheme of \(n\) points in the projective plane parameterizes degree \(n\) zero-dimensional subschemes of the projective plane. We examine the dual cones of effective divisors and moving curves on the Hilbert scheme. By studying interpolation, restriction, and stability properties of certain vector bundles on the plane we fully determine these cones for just over three fourths of all values of \(n\). A general Steiner bundle on \(\mathbb{P}^N\) is a vector bundle \(E\) admitting a resolution of the form \(0 \rightarrow \mathcal{O}_{\mathbb{P}^N} (−1)^s {M \atop \rightarrow} \mathcal{O}^{s+r}_{\mathbb{P}^N} \rightarrow E \rightarrow 0\), where the map \(M\) is general. We complete the classification of slopes of semistable Steiner bundles on \(\mathbb{P}^N\) by showing every admissible slope is realized by a bundle which restricts to a balanced bundle on a rational curve. The proof involves a basic question about multiplication of polynomials on \(\mathbb{P}^1\) which is interesting in its own right. / Mathematics
195

Physical properties of star-forming regions across the Galaxy

Dunham, Miranda Kay 13 June 2011 (has links)
The Bolocam Galactic Plane Survey (BGPS) has surveyed the northern Galactic plane at 1.1 mm and detected 8,358 sources. The BGPS catalog is large enough to characterize the properties of massive star formation in a statistically significant way. In this dissertation, I have conducted a survey of NH₃ lines toward 771 BGPS sources located throughout the Galactic plane. The NH₃ and 1.1 mm continuum observations together have allowed for complete characterization of the physical properties of these sources. I detected the NH₃(1,1) line toward 408 BGPS sources in the inner Galaxy, allowing for determination of their kinematic distances. At distances less than roughly 1 kpc, the BGPS detects predominately cores which will form a single star or small multiple system, while at distances between 1 and 7 kpc the BGPS detects predominately clumps which will form entire stellar clusters. At distances greater than 7 kpc, the BGPS detects the large scale clouds which contain clumps and cores. I have correlated the BGPS catalog with mid-IR catalogs of massive young stellar objects (MYSOs), and found that 49% of the BGPS sources contain signs of active star formation. The masses, densities, H₂ and NH₃ column densities, gas kinetic temperatures, and NH₃ velocity dispersions are higher in BGPS sources with associated mid-IR sources. I have also studied the physical properties of the BGPS sources as a function of Galactocentric radius, R[subscript Gal]. I find that the mean radius and mass decrease with increasing R[subscript Gal] but peak within the 5 kpc molecular ring where the gas kinetic temperature reaches a minimum. The fraction of BGPS sources with associated mid-IR sources decreases by 10% within the molecular ring. I postulate that these trends can be explained by an ambient gas density which decreases with R[subscript Gal], but peaks within the molecular ring. Similarly, the NH₃ column density and abundance decrease by almost an order of magnitude from the inner to outer Galaxy. / text
196

Modeling and Characterization of Plane Pair Structures in High-Speed Power Delivery Systems

Chen, Guang January 2006 (has links)
The power/ground plane structure within an electronic system not only delivers power, but also provides return path for the currents associated with the propagating signals. The cavity resonances within the power/ground plane structure affect the signal integrity of the system at high frequencies. The chip complexity and clock speed continue to increase and new structures, such as meshed planes and electromagnetic bandgap structures, are used in plane pair structure design. The signal integrity analysis of the power/ground plane structure becomes exceedingly important and challenging.The primary goal of this research is an in-depth investigation of the impact of the cavity resonances associated with the plane pair structure on the signal integrity. This includes development of modeling, simulation, and measurement methodologies for accurate and efficient characterization or prediction of the time/frequency domain electrical characteristics of power/ground plane pair structures. This research is divided into three parts. First, new SPICE compatible models are proposed for the new structures, such as the meshed plane and EBG embedded plane pair designs, so that the power/ground plane designs with these new structures can be simulated efficiently. Second, the accuracy of the simulation results is vital. The behavior of the benchmark structures is simulated and simulation results are verified either experimentally or by comparing with those from tools that are proven to be accurate. Third, high frequency measurement data is vulnerable to all parasitic parameters. The factors that affect the accuracy of measured data are investigated and methods to improve the accuracy of the measured data are proposed and verified.
197

RESEARCH ON VIDEO OBJECT PLANE WITH APPLICATION IN TELEOPERATIONS

Khan, Mohsin 23 April 2013 (has links)
Teleoperations is a significant field in robotics research; its applications range from emergency rooms in hospitals to space station orbiting the Earth to Mars rovers scavenging the red planet for microscopic life. We have developed a new user defined selective video object plane scheme. This selective filter works with standard H.264 encoder which is developed using Intel IPP and uses the latest multicore capabilities of new processors and can encode and transmit high definition videos over internet in real time. The area of interest is extracted and encoded at a different frame rate and noise level than rest of the frame. Our modified algorithm uses user input as well as motion detection of individual pixels to define video object plane. Video object plane filter is designed to be used for video with slow moving objects for cases like surgical procedures. The results of our compression algorithm have been verified using SSIM, PSNR and human perception survey. All these results of our VOP showed better performance than comparable encoders at the same bandwidth.
198

Seismic Assessment of Unreinforced Masonry Walls

Wijanto, Ludovikus Sugeng January 2007 (has links)
This thesis focuses on the seismic performance of unreinforced masonry wall perforated with a door opening representing typical URM walls of many aged masonry buildings in Indonesia. To obtain a test result that will be able to represent the local conditions, the experiments have been conducted in the Research Institute for Human Settlements (RIHS) laboratory in Bandung-Indonesia. Two 75 % unreinforced masonry (URM) walls with a 1½-wythe of solid clay-brick were constructed in Dutch bond configuration and tested until failure under quasi-static-reversed cyclic loading. Both units were loaded vertically by constant loads representing gravity loads on the URM wall’s tributary area. Both models were constructed using local materials and local labours. Two features were taken into account. First, it accommodated the influence of flanged wall and second, the URM wall was built on the stone foundation. The first URM wall represent the plain existing URM building in Indonesia and second strengthened by Kevlar fibre. It was observed from the test results that the URM wall Unit-1 did not behave as a brittle structure. It could dissipate energy without loss of strength and had a post-elastic behaviour in terms of “overall displacement ductility” value of around 8 to 10. As predicted, the masonry material was variable and non homogeneous which caused the hysteresis loop to be non symmetrical between push and pull lateral load directions. It can be summarized that Kevlar fibre strengthening technique is promising and with great ease of installation. Although Kevlar material is more expensive when compared to other fabrics as long as it was applied at the essential locations and in limited volumes, it can significantly increase the in-plane URM wall capacity. With appropriate arrangements of Kevlar fibre, a practicing engineer will be able to obtain a desired rocking mechanism in the masonry structure. Another advantage for the architectural point of view, very thin Kevlar fibres do not reduce the architectural space. Studies have also been undertaken to analyze the in-plane response of plain URM wall before and after retrofiting using the current seismic standard and the Finite Element Method (FEM).
199

PATTERN EVALUATION FOR IN-PLANE DISPLACEMENT MEASUREMENT OF THIN FILMS

Thota, Phanikrishna 01 January 2003 (has links)
The term Gossamer is used to describe ultra-lightweight spacecraft structures that solve the aerospace challenge of obtaining maximum performance while reducing the launch costs of the spacecraft. Gossamer structures are extremely compliant, which complicates control design and ground testing in full scale. One approach is to design and construct smaller test articles and verify their computational models experimentally, so that similar computational models can be used to predict the dynamic performance of full-scale structures. Though measurement of both in-plane and out-of-plane displacements is required to characterize the dynamic response of the surface of these structures, this thesis lays the groundwork for dynamic measurement of the in-plane component. The measurement of thin films must be performed using non-contacting sensors because any contacting sensor would change the dynamics of the structure. Moreover, the thin films dealt with in this work are coated with either gold or aluminum for special applications making the film optically smooth and therefore requiring a surface pattern. A Krypton Fluoride excimer laser system was selected to fabricate patterns on thin-film mirror test articles. Parameters required for pattern fabrication were investigated. Effects of the pattern on the thin-film dynamics were studied using finite element analysis. Photogrammetry was used to study the static in-plane displacement of the thin-film mirror. This was performed to determine the feasibility of the photogrammetric approach for future dynamic tests. It was concluded that photogrammetry could be used efficiently to quantify dynamic in-plane displacement with high-resolution cameras and sub-pixel target marking.
200

Effects of Maternal Nutrition Manipulation on Mares and Their Foals

Winsco, Kelly N 03 October 2013 (has links)
Previous research documented the fetus is sensitive to nutrition of the dam, but this has not been thoroughly investigated in horses. Objectives of the current studies were to determine effect of manipulation of maternal nutrition during the last third of pregnancy on mare performance, intake, hormones, foaling parameters, colostrum, and foal passive transfer of immunity and growth, and effects of supplemental arginine. Plane of nutrition influenced mare performance, and DMI was influenced by time with the first trial finding all mares consumed less in the 10th month of pregnancy compared to the 11th month, and the second trial finding all mares consumed less during the 11th month. Additionally, the second study determined arginine supplementation has no detrimental effects on DMI. Both studies indicated the dual marker system was sufficient at estimating DMI. Neither trial found an influence of treatment on foaling parameters or physical measurements obtained following parturition, and the second study determined arginine supplementation also did not affect foaling or measurements. The first study determined maternal nutrition did not affect foal growth or ADG. When colostrum quality was evaluated, the first study determined mares consuming only hay had increased specific gravity and Brix% indicating higher quality. This was confirmed by IgG analysis finding a tendency for increased IgG concentration. However, colostrum volume was not affected by nutrition, nor was total g IgG. The second study found contrasting results with greater specific gravity in mares on a high plane of nutrition, and a tendency for moderate plane of nutrition mares to have greater volume. Additionally, the second study determined that arginine supplementation does not influence colostrum volume or quality (measured by specific gravity or Brix %). In the first trial, maternal diets affected glucose and insulin AUC in mares, which altered insulin dynamics in the resulting foals. Foal insulin AUC and peak insulin concentration were greater in foals from mares supplemented with concentrate compared to foals from mares fed hay alone. These studies have provided a wealth of information to help elucidate the impact of maternal nutrition in late gestation on mares and their foals.

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