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Orbit design and estimation for surveillance missions using genetic algorithmsAbdelkhalik, Osama Mohamed Omar 12 April 2006 (has links)
The problem of observing a given set of Earth target sites within an assigned time
frame is examined. Attention is given mainly to visiting these sites as sub-satellite
nadir points. Solutions to this problem in the literature require thrusters to continuously
maneuver the satellite from one site to another. A natural solution is proposed.
A natural solution is a gravitational orbit that enables the spacecraft to satisfy the
mission requirements without maneuvering. Optimization of a penalty function is
performed to find natural solutions for satellite orbit configurations. This penalty
function depends on the mission objectives. Two mission objectives are considered:
maximum observation time and maximum resolution. The penalty function poses
multi minima and a genetic algorithm technique is used to solve this problem. In
the case that there is no one orbit satisfying the mission requirements, a multi-orbit
solution is proposed. In a multi-orbit solution, the set of target sites is split into
two groups. Then the developed algorithm is used to search for a natural solution
for each group. The satellite has to be maneuvered between the two solution orbits.
Genetic algorithms are used to find the optimal orbit transfer between the two orbits
using impulsive thrusters. A new formulation for solving the orbit maneuver problem
using genetic algorithms is developed. The developed formulation searches for a mini mum fuel consumption maneuver and guarantees that the satellite will be transferred
exactly to the final orbit even if the solution is non-optimal. The results obtained
demonstrate the feasibility of finding natural solutions for many case studies.
The problem of the design of suitable satellite constellation for Earth observing
applications is addressed. Two cases are considered. The first is the remote sensing
missions for a particular region with high frequency and small swath width. The second
is the interferometry radar Earth observation missions. In satellite constellations
orbit's design, a new set of compatible orbits, called the "Two-way orbits",whose
ground track path is a closed-loop trajectory that intersects itself, in some points,
with tangent intersections is introduced. Conditions are derived on the orbital elements
such that these Two-way Orbits exist and satellites flying in these orbits pass
the tangent intersection points at the same time. Finally, the recently proposed concept
of observing a space object from onboard a spacecraft using a star tracker is
considered. The measurements of the star tracker provide directions to the target in
space and do not provide range measurements. Estimation for the orbit of the target
space object using the measurements of the star tracker is developed. An observability
analysis is performed to derive conditions on the observability of the system states.
The Gaussian Least Squares Differential Correction Technique is implemented. The
results obtained demonstrate the feasibility of using the measurements of the star
tracker to get a good estimate for the target orbit within a period of measurements
ranging from about 20 percent to 50 percent of the orbital period depending on the
two orbits.
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Ground penetrating radar technique to locate coal mining related features: case studies in TexasSave, Neelambari R 12 April 2006 (has links)
The goal of this research project is to identify the efficacy of the ground
penetrating radar (GPR) technique in locating underground coal mine related subsidence
features at Malakoff and Bastrop, Texas. The work at Malakoff has been done in
collaboration with the Railroad Commission of Texas (RRC). RRC has been carrying
out reclamation of abandoned underground coal mines at Malakoff since the early
1990Âs. The history of the specific mining operations (at Malakoff and Bastrop) that
took place in the early 1900Âs has been difficult to ascertain; therefore, the use of a
geophysical techniques like ground penetrating radar to identify hidden voids and
potential subsidence features is vital for future reclamation process. Some of the
underground mine workings at the field site have collapsed over time affecting the
topography by creating sinkholes. GPR data, employing 25 MHz, 50 MHz and 100
MHz frequency antennae, have been collected in common offset patterns and azimuthal
pattern. GPR data indicate the mine tunnels possibly connecting existing sinkholes by
radargram hyperbolae that correspond with mine openings observed visually or during
reclamation. This study also denotes the importance of understanding the variable
physical properties of the stratigraphy, which could lead to false alarms by
misinterpretation of the radar signals. Natural and man-made above-ground structures
cause obstructions in data collection, and hence an optimal design is required for each
survey. RRC successfully ground-truthed the data during its reclamation process. In
turn, the acquired geophysical data helped to guide the reclamation. At Bastrop, GPR
data along with historical documentation led to the conclusion that coal mining did exist
in this region but is not a major concern to the immediate stability and safety of the field
site. It can be concluded from both the studies that the GPR technique identifies
anomalous shafts/tunnels possibly connecting potential failure.
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Effect of sorghum bran addition on lipid oxidation and sensory properties of ground beef patties differing in fat levelsHemphill, Susan Patricia 30 October 2006 (has links)
Oxidation of lipids influences the color and sensory qualities of meat products.
Meat with a high fat content, such as ground meat, is susceptible to lipid oxidation that
leads to the development of negative flavor and color changes. Antioxidants, such as
butylated hydroxanisole (BHA), butylated hydroxytolune (BHT) and extracts of
rosemary, are used in meat products to control the effects of lipid oxidation. Awika
(2000, 2003) found that sorghum bran phytochemicals have high antioxidant properties.
Our objective is to evaluate the pH, color, sensory and antioxidant effect of 10, 20 and
30% ground beef patties containing rosemary, BHA/BHT, and three levels of sorghum
bran during 5 d of aerobic storage at 4ðC.
Beef trimmings containing either 50% or 90% lean were formulated into three
meat blocks containing either 10, 20 or 30% lipid. Within a fat content, ground beef was
equally divided into one of six treatments: 1) control-no added ingredients; 2) BHA and
BHT at .01% of the meat weight; 3) rosemary at 0.2% of the meat weight; 4) high level
of sorghum at 1.0% of the meat weight; 5) medium level of sorghum at 0.5% of the meat
weight; and, 6) a low level of sorghum at 0.25% of the meat weight. The ground beef was aerobically packaged and stored for 0, 1, 3, or 5 days at 4ðC. pH, thiobarbituric acid
reactive substances (TBARS), fatty acid methyl esters (FAME), sensory color, Minolta
color space values and descriptive sensory evaluations were determined.
Antioxidant addition reduced TBARS values and increased hardness (P<0.020)
and springiness (P=0.002) over time compared to controls. The addition of the high
sorghum bran level resulted in lower raw color scores (2.0 vs. 2.9) (P<0.0001) and
slightly increased bitter basic taste (2.47 vs. 2.65) (P=0.0069) when compared to control
patties. The high sorghum level slightly increased pH (6.33 vs. 6.41) (P<0.0001) and
resulted in darker (P<0.0001) and less yellow colored (P<0.0001) patties. With storage,
patties had higher pH (P<0.0001) and color space values decreased (P<0.0001). Sensory
properties of the patties differed across fat levels (P<0.05); however, interactions
between fat level and antioxidant treatment were not significant (P>0.05).
Moreover, the addition of sorghum bran at low levels can retard oxidative
rancidity in ground beef patties without causing detrimental color changes and
negatively affecting sensory attributes.
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Grundwasser - Altlasten AktuellBöhm, Anna, Sohr, Antje, Gruhne, Sabine, Zweig, Maren, Ihling, Heiko 18 January 2010 (has links) (PDF)
Die Schriftenreihe gibt in 11 Fachbeiträgen die Ergebnisse aktueller Projekte und Forschungsvorhaben des LfULG wieder. Die Themen sind breit gefächert und beinhalten beim Grundwasser die Nitratbelastung an der Wasserfassung Diehsa, das Vorhaben eines digitalen Hydroisohypsenplanes in Sachsen, Sensor- und Thermo-Flowmetermessungen für den Ersatz von Grundwasseraufschlüssen sowie Informationen zum Projekt KLIWES mit Abschätzung der Auswirkungen der Klimaveränderungen auf den Wasserhaushalt in Sachsen.
Die Themen des Altlastenbereiches umfassen neben dem Sächsischen Altlastenkataster die Schwerpunkte Sickerwasserprognose, Resorptionsverfügbarkeit von Schadstoffen aus Böden der Erzgebirgsregion, die Flutung der Grube Königstein und Informationen zum Projekt SUMATECS zur Anwendung sanfter Sanierungsverfahren. Die Vernetzung der einzelnen Fachdisziplinen wie z. B. bei Klimaänderungen oder der EU-Wasserrahmenrichtlinie (WRRL) spielt dabei eine immer größer werdende Rolle.
»Grundwasser - Altlasten aktuell« erscheint mit dieser Ausgabe erstmals als Heft der Schriftenreihe.
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Countermeasures against railway ground and track vibrationsHildebrand, Robert January 2001 (has links)
<p>Railway track and ground vibrations are considered, with anemphasis on methods of mitigation ("countermeasures"), forapplication to wayside disturbance problems.</p><p>Original field measurements from two sites in Sweden, aswell as borrowed measurements from Norway, provide vibrationresults at many points on the track, on and underneath theground surface, for a variety of trains, both with and withoutcountermeasures in-place.</p><p>Infinite periodic system theory is the basis of track-onlyand track-ground interaction models presented. The repeatingelement includes the sleeper, pad-fastener, rail, and either alocally-reacting ballast or a continuous ballast-soilwaveguide. The track-only model is even refined for nonlinearand high-frequency cases. The models are suitable for studyingcountermeasures in the track, or in the foundation(soil-stabilization). This latter countermeasure is shown to beeffective at low frequencies (of geotechnical interest), butsometimes counterproductive at audible frequencies (disturbanceproblems).</p><p>An analytical model for hard seismic screens is alsopresented, to complement the treatment of ground vibrationcountermeasures; this is based on physical approximations whichare favored by "high" (i.e, audible)frequencies and softsoils. Notably, experimentally observed resonant behavior isexplained.</p><p><b>Keywords:</b>ground vibration, vibration screen, trackvibration, railway vibration</p>
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Kommunikation i Designer- Klientinteraktionen : Användning av objekt för att uppdatera Common GroundLinde, Eva January 2008 (has links)
<p>En designers främsta uppgift är att hitta lösningar på problem som är svårformulerade vilket kräver full förståelse för designsituationen. Interaktionsdesignern fungerar dessutom som länk mellan olika aktörer i en beställarprocess med syfte att tillgodose slutanvändarens behov, som ofta faller mellan stolarna. Avsikten med denna rapport är att studera hur interaktionsdesignern kan vara den kommunikatör som krävs. Detta har gjorts genom att titta på hur objekt används i kommunikationen mellan designern och dess klient. Studien är gjord genom en videoanalys som tolkats utifrån Herbert H. Clarks kommunikationsanalytiska termer. Common ground används som representation för den ömsesidiga förståelse som här önskas belysas. Videomaterialet är hämtat från ett större forskningsprojekt där olika designgrupper tillsammans med kronofogdemyndigheten arbetar i workshops för att ta fram ett nytt IT-stöd.</p><p>Objekt visar sig vara viktiga verktyg för att orientera sig i ett samtal och för att representera information. De blir därmed viktiga för att hänvisa till common ground och säkra dess innehåll. Det är viktigt att lyfta interaktionsdesignerns roll för slutanvändaren och de verktyg och metoder denne kan behöva för att kommunicera och hitta lösningar på designproblem. Det finns därmed behov av fungerande ramverk för studier kring kommunikation, vilket visar sig kräva mer kunskap.</p>
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Hydrogeologic characterization of fractured carbonate aquifers employing ground-penetrating radar /Tsoflias, Georgios Padelis, January 1999 (has links)
Thesis (Ph. D.)--University of Texas at Austin, 1999. / Vita. Includes bibliographical references (leaves 91-95). Available also in a digital version from Dissertation Abstracts.
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3-D numerical simulation and design of tensioned roof bolting for underground coal minesZhang, Yunqing, January 1900 (has links)
Thesis (Ph. D.)--West Virginia University, 2003. / Title from document title page. Document formatted into pages; contains xiv, 183 p. : ill. (some col.). Vita. Includes abstract. Includes bibliographical references (p. 179-182).
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Effect of in-situ stresses on the stability of coal mine development workingsGadde, Murali Mohan. January 2003 (has links)
Thesis (M.S.)--West Virginia University, 2003. / Title from document title page. Document formatted into pages; contains xii, 130 p. : ill. (some col.), map (part col.). Includes abstract. Includes bibliographical references (p. 127-130).
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Site amplification model for use in ground motion prediction equationsNavidi, Sara 12 February 2013 (has links)
The characteristics of earthquake shaking are affected by the local site conditions. The effects of the local soil conditions are often quantified via an amplification factor (AF), which is defined as the ratio of the ground motion at the soil surface to the ground motion at a rock site at the same location. Amplification factors can be defined for any ground motion parameter, but most commonly are assessed for acceleration response spectral values at different oscillator periods. Site amplification can be evaluated for a site by conducting seismic site response analysis, which models the wave propagation from the base rock through the site-specific soil layers to the ground surface. An alternative to site-specific seismic response analysis is site amplification models. Site amplification models are empirical equations that predict the site amplification based on general characteristics of the site. Most of the site amplification models that already used in ground motion prediction equations characterize a site with two parameters: the average shear wave velocity in the top 30 m (VS30) and the depth to bedrock. However, additional site parameters influence site amplification and should be included in site amplification models.
To identify the site parameters that help explain the variation in site amplification, ninety nine manually generated velocity profiles are analyzed using seismic site response analysis. The generated profiles have the same VS30 and depth to bedrock but a different velocity structure in the top 30 m. Different site parameters are investigated to explain the variability in the computed amplification. The parameter Vratio, which is the ratio of the average shear wave velocity between 20 m and 30 m to the average shear wave velocity in the top 10 m, is identified as the site parameter that most affects the computed amplification for sites with the same VS30 and depth to bedrock.
To generalize the findings from the analyses in which only the top 30 m of the velocity profile are varied, a suite of fully randomized velocity profiles are generated and site response analysis is used to compute the amplification for each site for a range of input motion intensities. The results of the site response analyses conducted on these four hundred fully randomized velocity profiles confirm the influence of Vratio on site amplification. The computed amplification factors are used to develop an empirical site amplification model that incorporates the effect of Vratio, as well as VS30 and the depth to bedrock. The empirical site amplification model includes the effects of soil nonlinearity, such that the predicted amplification is a function of the intensity of shaking. The developed model can be incorporated into the development of future ground motion prediction equations. / text
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