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Offshore Oil Slick Detection With Remote Sensing TechniquesAkar, Sertac 01 September 2007 (has links) (PDF)
The aim of this thesis is to develop a methodology for detection of naturally occurring offshore oil slicks originating from hydrocarbon seeps using satellite remote sensing techniques. In this scope, Synthetic Aperture Radar (SAR) imagery has been utilized. Case study area was Andrusov High in the Central Black Sea. Hydrocarbon seepage from tectonic or stratigraphic origin at the sea floor causes oily gas plumes to rise up to the sea surface. They form thin oil films on the sea surface called oil slicks. Presence of seeps and surface oil slicks for the offshore basins is a trace of depleted oil traps. Spatial distribution of oil slicks is closely related to sea waves, dominant wind patterns and weathering factors. Even though, there are oil slick detection techniques available with optical remote sensing, laser fluorosensors, and hyperspectral remote sensing, the most efficient results can be obtained from active microwave sensors like synthetic aperture radar (SAR). SAR sensors simply measure the backscattered radiation from the surface and show the roughness of the terrain. Oil slicks dampen the sea waves creating dark patches in the SAR image. In this context an adapted methodology has been proposed, including three levels namely / visual inspection, image filtering and object based fuzzy classification. With visual inspection, targets have been identified and subset scenes have been created. Subset scenes have been categorized into 3 cases based on contrast difference of dark spots to the surroundings. Then object based classification has been utilized with the fuzzy membership functions defined by extracted features of layer values, shape and texture from segmented and filtered SAR subsets. As a result, oil slicks have been discriminated from look-alikes which are the phenomena resembling oil slicks. The overall classification accuracy obtained by averaging three different cases is 83 % for oil slicks and 77 % for look-alikes. The results of this study can considered to be a preliminary work and supplementary information for determining the best operational procedure of offshore hydrocarbon exploration.
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An Implementation And Algorithm Development For Uwb Through The Wall Imaging SystemKasak, Kerem 01 December 2007 (has links) (PDF)
The feasibility of Ultra Wide Band (UWB) through the wall surveillance system is
studied in this thesis. The transmitter and receiver architectures are discussed and an
experimental set-up is constructed to verify the theory of UWB sensing. The constructed
system has 80 mW peak, 6 uW average transmit power and 500 kHz PRF and a range
resolution better than 1 cm. Using the experimental set-up, two problems are examined.
The first problem is the respiration rate detection problem. It has been shown that the
respiration rate can be accurately estimated and the signs of vital activity can be
determined behind the wall. The second problem studied in this thesis is the through the
wall imaging problem. The imaging system is based on the construction of a synthetic
aperture by sliding the transmit-receive antenna pair along the cross range direction. The
cross range resolution is improved by applying a migration algorithm to the collected
data. It has been shown that imaging of a scene 8 meters in range, behind a wall of 20 cm
thickness is possible with the available power.
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Comparative Evaluation Of Sar Image Formation AlgorithmsSahin, Halil Ibrahim 01 September 2010 (has links) (PDF)
In the scope of this thesis, simulation-based analyses and comparative evaluation of Synthetic Aperture Radar (SAR) image formation techniques, namely Time Domain Correlation, Range Stacking, Range Doppler and Chirp Scaling algorithms, are presented.
For this purpose, first, the fundamental concepts of SAR such as SAR geometry, resolution and signal properties are explained. A broadside SAR simulator that provides artificial raw data as an input to the algorithms is designed and implemented. Then, the mathematical background of the imaging algorithms discussed in the thesis is provided. Implementations of these algorithms and simulations are carried out using MATLAB® / . Finally, simulation results are presented and discussed to show the advantages and disadvantages of the algorithms.
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The Major Piano Works of Cesar FranckLiou, Yi-Chun 17 July 2002 (has links)
The thesis consists of five chapters. Chapter One is the discussion of background, including the development of keyboard music after 17th century in France, and famous composers with their styles of creation. Chapter Two focuses on César Franck¡¦s developmental track of music and his creation of masterpieces. Chapter Three depends on compositional style, dividing into two periods to discuss Franck¡¦s piano music. Chapter Four mainly introduces Franck¡¦s unique creative technique of piano music, featuring the traditional influence from polyphonic and contrapuntal music in Baroque era, cyclic form, phrasing structure and harmonic language. Chapter Five separately discusses formal structure and characteristic features in Prélude, Chorale et Fugue and Prélude, Aria et Final. Finally, we make a conclusion for the whole research.
In 19th century, Franck was one of the most important piano composers in France. Prélude, Chorale et Fugue and Prélude, Aria et Final were his most important works, sufficiently presenting Franck¡¦s distinguished compositional style. They opened not only a new field for his composite of piano music, but also brought deep influence on many following composers.
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Traitements temps-fréquence pour l'analyse de scènes complexes dans les images SAR polarimétriquesLeducq, Paul 08 June 2006 (has links) (PDF)
Ces travaux concernent l'utilisation de méthodes temps-fréquences pour l'étude des images SAR polarimétriques au travers de deux applications.<br />La réponse des cibles mobiles est étudiée. Sa forme particulière conduit à une méthode de détection et refocalisation basée sur la transformée de Fourier fractionnaire. La problématique est étendue au cas des cibles possédant de plus une réflectivité dépendant des paramètres d'illumination (angle et fréquence). Une approche basée sur une modélisation de la cible et sur l'algorithme de Matching-Pursuit est présentée.<br />La détection des bâtiments dans les images SAR de zones urbaines en bande L est abordée dans le cadre temps-fréquence. Les notions complémentaires de stationnarité et de cohérence sont exploitées pour produire une classification temps-fréquence, permettant d'identifier les environnements naturels et différents types de cibles artificielles. Des applications à la cartographie et à la caractérisation de bâtiments sont proposées.
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台灣股票市場除權效應之實證研究 / The Empirical Result on Dividend Effect of Taiwan Stock Market盧偉文 Unknown Date (has links)
參考從2001到2005在台灣股市的股息對股票的影響的研究,在根據event-study and SAR method這兩種方式之實證研究可以得到本次的台灣股市裡面除權的效應。 / Referring to our research into the ex-dividend effects on stocks traded on TSE from 2001 to 2005, we come to the following conclusions under the event-study and SAR method. There should be negative ARs on the three days prior to the ex-date and a positive AR on the ex-dividend day, no matter in a bear or bull market. Stocks with cash-only dividends present lower ARs on the three days prior to the ex-date and the ex-dividend day while stock-only dividend ones suffer from higher ARs. The performances of stocks with balanced dividends are just in-between. The most significant ex-dividend effects turn up when it comes to stocks which go ex-dividend in season, with a positive CAR to the seventh day after the ex-date. On the other hand, the effects on the early-ex-dividend stocks exhibit insignificance generally. Later-ex-dividend stocks demonstrate the lowest fluctuation of ARs. However, the simultaneous decline of the index in the ex-dividend season is likely to result in higher-significant ARs. In terms of industry, the ex-dividend effects on electronic companies are more significant than on non-electronic companies. Given a bear market, there used to be negative CARs on electronic companies after shareholders’ meeting; on the contrary, in a bull market, there were positive CARs.
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Lead Discovery and Optimization Strategies Towards the Development of 4(1H)-Quinolones and 1,2,3,4-Tetrahydroacridone Analogs with Antimalarial ActivityCross, Richard Matthew 01 January 2011 (has links)
The goal of our research endeavor was to successfully employ modern lead discovery and optimization strategies towards the development and identification of compounds possessing antimalarial activity. Preliminary data from in vitro screening at the Walter Reed Army Institute of Research identified several chemotypes including 4(1H)-quinolones and 1,2,3,4-tetrahydroacridones to have potent antimalarial activities. Multiple synthetic routes were devised and implemented which enabled the rapid preparation and isolation of over 400 structurally diverse 4(1H)-quinolones and 1,2,3,4-tetrahydroacridones.
Our research towards discovering and optimizing antimalarials was inspired from the severe impact malaria has had on our planet especially on impoverished countries. There are over 300 million cases annually and over one million deaths. The staggering mortality rates combined with the global emergence of chemical resistance that the parasite Plasmodium falciparum has developed towards many of the common antimalarials compelled us to extend our research efforts to this growing problem. The need for identifying and developing new antimalarial drugs is very important. However, our approach focuses on the optimization of historic antimalarials such as endochin, floxacrine, or ICI 56,780 which possess liabilities such as lack of poor solubility, poor in vivo activity or lingering toxicity issues. Through these optimization efforts using both SAR and structure-property relationship (SPR) studies, a more suitable candidate was developed that had superior physicochemical properties.
Our drug design approach included not only the identification of liabilities of historic compounds but also the synthesis and optimization of numerous analogs guided by SAR. All compounds were tested in vitro for antimalarial activity and characterized in parallel for physicochemical properties such as solubility, permeability, and logD7.4. Insights from both the antimalarial activity as well as the physicochemical properties determined which analogs would be advanced in the design process.
Based on our early investigations, 6-chloro-7-methoxy-3-phenyl-4(1H)-quinolone emerged as a promising hit. Compared to endochin, which possesses EC50s of 8.6 nM and 46.6 nM against drug resistant strains W2 and TM90C2B, and a solubility of less than 2 µM, 6-chloro-7-methoxy-3-pheny-4(1H)-quinolone was superior with a 4-fold improvement in solubility (6 µM) as well as slightly improved antimalarial activity (EC50s of 26.2 nM and 15.3 nM against W2 and TM90C2B, respectively). Unfortunately, this compound failed to reduce parasitemia levels in P. berghei infected mice. Hit-to-lead optimization lead to the discovery of 6-chloro-7-methoxy-2-methyl-3-o-tolyl-4(1H)-quinolone which was shown to reduce parasitemia levels by 41% at day 6 post-exposure (PE) in P. berghei infected mice at a 50 mg/kg dose. The observed in vivo activity of 6-chloro-7-methoxy-2-methyl-3-o-tolyl-4(1H)-quinolone was believed to relate to the 3-fold increase in solubility (19 µM) over the 3-phenyl-susbtituted analogue. Continuation of SAR and SPR studies identified additional 4(1H)-quinolones suggesting that the microsomal stability of the compounds is as important for in vivo efficacy as the aqueous solubility. Several of the analogs that showed minimal degradation in human microsomal stability studies demonstrated increased in vivo activity in the ranges of 72-98% parasitemia reductions on day 6PE in P. berghei infected mice at 50 mg/kg. These results helped refine the final SAR and SPR optimization identifying a compound with radical curative activity in mice (99% parasitemia reductions on day 6PE in P. berghei infected mice at 50 mg/kg with five out of five mice surviving beyond 30 days).
Theses studies not only highlight the effectiveness of detailed SAR and SPR strategies used in drug discovery programs, but they also showcase the importance of re-evaluating historic antimalarials and exploiting their shortcomings. These studies have opened the doors to several possibilities regarding the 4(1H)-quinolone scaffold optimization for future antimalarial development. Several of the compounds described in this work are currently being subjected to stringent head-to-head comparative studies to determine the analog best suited for pre-clinical trials.
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An Investigation into the Effects of Variable Lake Ice Properties on Passive and Active Microwave Measurements Over Tundra Lakes Near Inuvik, N.W.T.Gunn, Grant 25 September 2010 (has links)
The accurate estimation of snow water equivalent (SWE) in the Canadian sub-arctic is integral to climate variability studies and water availability forecasts for economic considerations (drinking water, hydroelectric power generation). Common passive microwave (PM) snow water equivalent (SWE) algorithms that utilize the differences in brightness temperature (Tb) at 37 GHz – 19 GHz falter in lake-rich tundra environments because of the inclusion of lakes within PM pixels. The overarching goal of this research was to investigate the use of multiple platforms and methodologies to observe and quantify the effects of lake ice and sub-ice water on passive microwave emission for the purpose of improving snow water equivalent (SWE) retrieval algorithms.
Using in situ snow and ice measurements as input, the Helsinki University of Technology (HUT) multi-layer snow emission model was modified to include an ice layer below the snow layer. Emission for 6.9, 19, 37 and 89 GHz were simulated at horizontal and vertical polarizations, and were validated by high resolution airborne passive microwave measurements coincident with in situ sampling sites over two lakes near Inuvik, Northwest Territories (NWT). Overall, the general magnitude of brightness temperatures were estimated by the HUT model for 6.9 and 19 GHz H/V, however the variability was not. Simulations produced at 37 GHz exhibited the best agreement relative to observed temperatures. However, emission at 37 GHz does not interact with the radiometrically cold water, indicating that ice properties controlling microwave emission are not fully captured by the HUT model.
Alternatively, active microwave synthetic aperture radar (SAR) measurements can be used to identify ice properties that affect passive microwave emission. Dual polarized X-band SAR backscatter was utilized to identify ice types by the segmentation program MAGIC (MAp Guided Ice Classification). Airborne passive microwave transects were grouped by ice type classes and compared to backscatter measurements. In freshwater, where there were few areas of high bubble concentration at the ice/water interface Tbs exhibited positive correlations with cross-polarized backscatter, corresponding to ice types (from low to high emission/backscatter: clear ice, transition zone between clear and grey ice, grey ice and rafted ice). SWE algorithms were applied to emission within each ice type producing negative or near zero values in areas of low 19 GHz Tbs (clear ice, transition zone), but also produced positive values that were closer to the range of in situ measurements in areas of high 19 GHz Tbs (grey and rafted ice). Therefore, cross-polarized X-band SAR measurements can be used as a priori ice type information for spaceborne PM algorithms, providing information on ice types and ice characteristics (floating, frozen to bed), integral to future tundra-specific SWE retrieval algorithms.
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Investigation of gradient echo MRI for blood vessel imaging and susceptibility-weighted imaging in the human brainEissa, Amir Unknown Date
No description available.
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Mobile Phone Antenna DesignSaif, Khalid, Alsmadi, Nazem January 2015 (has links)
This thesis focuses on mobile phones antenna design with brief description about the historical development, basic parameters and the types of antennas which are used in mobile phones. Mobile phones antenna design section consists of two proposed PIFA antennas. The first design concerns a single band antenna with resonant frequency at GPS frequency (1.575GHz). The first model is designed with main consideration that is to have the lower possible PIFA single band dimensions with reasonable return loss (S11) and the efficiencies. Second design concerns in a wideband PIFA antenna which cover the range from 1800MHz to 2600MHz. This range covers certain important bands: GSM (1800MHz & 1900MHz), UMTS (2100MHz), Bluetooth & Wi-Fi (2.4GHz) and LTE system (2.3GHz, 2.5GHz, and 2.6GHz). The wideband PIFA design is achieved by using slotted ground plane technique. The simulations for both models are performed in COMSOL Multiphysics. The last two parts of the thesis present the problems of mobile phones antenna. Starting with Specific absorption rate (SAR) problem, efficiency of Mobile phones antenna, and hand-held environment.
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