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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.
951

Design And Optimization Of Uwb Antenna For Air Coupled Gpr Applications

Ahmed, Amr 01 January 2014 (has links)
This thesis presents a novel antenna structure that satisfies the challenging requirements of an air coupled high speed ground penetrating radar (GPR). The desired GPR system is to achieve high spatial resolution and accurate inspection results while scanning at relatively high speed for highway pavement and bridge deck inspection. This work utilizes the Ultra Wide Band (UWB) antenna design to achieve both physical and electrical requirements imposed. The design procedure starts with a short survey to discuss typical UWB antennas used for GPR applications, and various tradeoffs of each type specifically when used for Air Coupled GPR applications. Our structure anatomy is presented, followed by a theory introduction that mainly focuses on achieving good impedance matching throughout the proposed antenna structure. A proof-of-concept MATLAB model is created to evaluate the preliminary physical dimensions that can achieve minimum reflections at antenna's feed point. These dimensions are then used in SolidWorks to create a 3D model that is imported later in HFSS to obtain accurate electromagnetic characteristics. Furthermore, fine tunings are performed to the antenna structure to optimize both gain and impedance matching. The SolidWorks 3-D structural model is finally used for antenna fabrication. The measurements recorded from the field experiments using the prototypes manufactured are compared to the simulation results confirming our initial findings. Both measurements and simulation results demonstrated very small reflection loss across the 700 MHz ~ 6 GHz frequency band with a very high directed gain and radiation efficiency.
952

Cmos Programmable Time Control Circuit Design For Phased Array Uwb Ground Penetrating Radar Antenna Beamforming

Reilly, Nicholas James 01 January 2017 (has links)
Phased array radar systems employ multiple antennas to create a radar beam that can be steered electronically. By manipulating the relative phase values of feeding signals among different antennas, the effective radiation pattern of the array can be synthesized to enhance the main lobe in a desired direction while suppressing the undesired side lobes in other directions. Hence the radar scanning angles can be electronically controlled without employing the bulky mechanical gimbal structure, which can significantly reduce radar system size, weight and power consumption. In recent years, phased array technologies have received great attentions and are explored in developing many new applications, such as smart communication systems, military radars, vehicular radar, etc. Most of these systems are narrow band systems, where the phase delays are realized with narrow band phase shifter circuits. For the impulse ground penetrating radar however, its operating frequency spans an ultrawide bandwidth. Therefore the traditional phase shifters are not applicable due to their narrow band nature. To resolve the issue, in this study, a true time delay approach is explored which can precisely control time delays for the feeding pulse signals among different antennas in the array. In the design, an on chip programmable delay generator is being developed using Global Foundry 0.18 µm 7 HV high voltage CMOS process. The time delay control is realized by designing a programmable phase locked loop (PLL) circuit which can generate true time delays ranging from 100 ps (picoseconds) to 500 ps with the step size of 25 ps. The PLL oscillator's frequency is programmable from 100MHz to 500MHz through two reconfigurable frequency dividers in the feedback loop. As a result, the antenna beam angle can be synthesized to change from 9.59° to 56.4° with a step of 2.75°, and the 3dB beamwidth is 10°. The power consumption of the time delay circuit is very low, where the supply voltage is 1.8V and the average current is as low as 472uA.
953

La ville aux frontières : les perles de traite à Montréal aux XVIIe et XVIIIe siècles

Lamothe, Francis January 2006 (has links)
Mémoire numérisé par la Direction des bibliothèques de l'Université de Montréal.
954

Design for ground beetle abundance and diversity sampling within the National Ecological Observatory Network

Hoekman, David, LeVan, Katherine E., Ball, George E., Browne, Robert A., Davidson, Robert L., Erwin, Terry L., Knisley, C. Barry, LaBonte, James R., Lundgren, Jonathan, Maddison, David R., Moore, Wendy, Niemelae, Jari, Ober, Karen A., Pearson, David L., Spence, John R., Will, Kipling, Work, Timothy 04 1900 (has links)
The National Ecological Observatory Network (NEON) will monitor ground beetle populations across a network of broadly distributed sites because beetles are prevalent in food webs, are sensitive to abiotic factors, and have an established role as indicator species of habitat and climatic shifts. We describe the design of ground beetle population sampling in the context of NEON's long-term, continentalscale monitoring program, emphasizing the sampling design, priorities, and collection methods. Freely available NEON ground beetle data and associated field and laboratory samples will increase scientific understanding of how biological communities are responding to land-use and climate change.
955

Akustická komunikace a její variabilita u vybraných populací syslů rodu Spermophilus. / Acoustic communication and its variability in selected populations of ground squirrels of the genus Spermophilus

Schneiderová, Irena January 2012 (has links)
The thesis deals with vocalizations produced by Eurasian ground squirrels of the genus Spermophilus. It is mainly focused on inter-species and intra-species variability in acoustic structure of alarm calls which are emitted in presence of predators.The major part of the thesis deals with intra-species variability in acoustic structure of the alarm calls in five Eurasian ground squirrels, Spermophilus citellus, S. taurensis, S. xanthoprymnus, S. suslicus and S. fulvus. It has been confirmed that the alarm calls of these ground squirrels show a high level of species specificity. The thesis further describes another vocalizations produced by three Eurasian ground squirrel species, Spermophilus suslicus, S. citellus and S. fulvus, and shows that with the exception of the alarm calls, vocal repertoires of these three ground squirrels are remarkably similar. The last part of the thesis deals with individual distinctiveness of the alarm calls of three Eurasian ground squirrels, Spermophilus citellus, S. taurensis and S. xanthoprymnus. It has been shown that the alarm calls of these species have a significant potential to encode information about caller identity.
956

Rozpoznávání a klasifikace polygonálních struktur mrazových klínů z dat DPZ / Recognition and classification of patterned ground polygons from remote sensing data

Kříž, Jan January 2013 (has links)
Recognition and classification of patterned ground polygons from remote sensing data Abstract The main objective of this thesis has been to prove the possibility of using object based image analysis classification for identification of the ice-wedge polygons and to find general method for their classification. The thesis contains a comparison of the object based and pixel based classification of the subject. The three classification rulesets for OBIA were developed on three test sites on Mars captured by HiRISE sensor. As a result, the general classification approach is suggested. The manually collected datasets, which are common in geomorphological research, were used as the reference sample. The OBIA classification provided better results in all three cases, whereas the pixel classification was valid in only one case. Another objective has been the automatization of the process of gaining information about morphometric characteristics of the ice-wedge polygons and the subsequent classification of the polygons. Within the scope of the process were developed methods for creating polygonal network and specified parameters of those methods. Several toolboxes for the ArcGIS software were prepared and they are part of the results of the thesis. Keywords: patterned ground, ice-wedge polygons, remote sensing,...
957

Teplotní a vlhkostní režim strukturních půd Vysokých Tater / Thermal and moisture regime of patterned ground in the High Tatras

Pechačová, Blanka January 2013 (has links)
6 ABSTRACT Thermal and moisture regime of patterned ground is closely associated with the presence of the regelation phenomenon. Generally, the regelation includes all processes leading to the water freeze-thaw alternations in soil or bedrock. As a result of cyclic freezing and thawing of soil water under specific conditions, processes, such a moisture migration, ice segregation or frost heaving, operate. Termal and moisture regime is the main factor of these processes and consequentely, of the patterned ground formation. The submited diploma thesis is concerned with thermal and moisture regime of patterned ground in the High Tatras. The main aims of the thesis was to characterize thermal and moisture regime of patterned ground, to evaluate and confront the patterned ground regelation activity depending on the diverse soil depths and different types of the patterned ground and to evaluate the soil temperature relationship to the air temperatures, soil moisture content and the water level regime of the nearest lakes. The partial purpose of the thesis was to assess the applicability of different methods of the regelation cycle determination based on the soil temperature measurements. During the study period 2007 - 2012 the regelation activity of sorted paterned ground (Hincove oká, Lúčne sedlo and Skalnaté...
958

Effects of subprimal, quality grade, and aging on display color and sensory properties of ground beef patties

Highfill, Carrie January 1900 (has links)
Master of Science / Food Science / John Unruh / A factorial arrangement of treatments was used to evaluate the effects of two subprimal types (chuck roll and knuckle), two quality grades (Premium Choice and Select), and three vacuum storage aging times before processing (7, 21, and 42 d) on ground beef patty display color stability and sensory attributes. At the end of each aging time, four knuckles or two chuck rolls representing their respective quality grade categories were combined and ground to form a sample batch. After a final grind, patties were formed using a patty machine, packaged in overwrapped trays, and displayed in a coffin-type retail case under continuous fluorescent lighting. Ground beef patties from chuck roll and Premium Choice subprimals had brighter red visual color scores, less discoloration, and higher (P<0.05) L*, a*, b*, and chroma values than those from knuckle and Select subprimals, respectfully. With increased display time, patties became (P<0.05) darker red and more discolored and had decreased L*, a*, b*, a/b ratio, and chroma values and increased hue angle values. Ground beef patties from Select knuckle subprimals had greater (P<0.05) oxygen consumption rate (OCR) than those from Premium Choice chuck roll, Select chuck roll and Premium Choice knuckle subprimals. Patties from subprimals aged 42 d had a lower metmyoglobin reducing ability (MRA) than those from subprimals aged 7 and 21 d. Greater aging and display times had higher (P<0.05) aerobic and lactic acid plate counts. In addition, thiobarbituric acid reactive substances values increased (P<0.05) from 7 to 21 d of aging and from 0 to 24 h of display. Ground beef patties from Premium Choice subprimals had a higher MUFA:SFA ratio (P<0.05) than those from Select subprimals. All treatments had acceptable sensory panel results with minimal differences due to treatment. Lower (P<0.05) peak force values for slice shear force and Lee-Kramer were recorded for patties from chuck roll, Premium Choice, and 42 d aged subprimals than those from knuckle, Select, and 7 d aged subprimals, respectfully. Overall, Premium Choice chuck rolls aged for fewer days would result in the most color stability and extended display life.
959

Comparison of dynamic and unconfined compression strength for machine footing design

Brennan, Jim January 2011 (has links)
Typescript (photocopy). / Digitized by Kansas Correctional Industries
960

The Usefulness of Ground Penetrating Radar in locating burials in Charity Hospital Cemetery, New Orleans

Mitchell, Monique Tashell 16 May 2008 (has links)
The Charity Hospital Cemetery in New Orleans, Louisiana, was used as a potter's field for over 150 years. When Charity Hospital considered selling a portion of the property ground penetrating radar (GPR) and thermal infrared (TIR) data were collected in the cemetery to locate unmarked graves. The TIR data could not be used because the expert died before compiling the TIR data. Therefore, the GPR data was the sole source of subsurface information. GPR anomalies were used to excavate 3 areas where bones and hospital supplies were subsequently found, unfortunately very limited analyses were possible on the analog GPR data. The study presented here involved digitizing data and conducting a more thorough analysis of map patterns to determine whether GPR data could be used reliably to locate burials in the cemetery. The study's result indicates that GPR is a reliable source for burial detection and other anomalies in the subsurface.

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