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1
Gautero, François. "CW-complexes dynamiques". Nice, 1998. http://www.theses.fr/1998NICE5137.
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On définit à partir de quelques conditions algébriques simples une classe de CW-complexes, appelés CW-complexes dynamiques. On montre que ces CW-complexes dynamiques ont la propriété de porter un semi-flot non singulier. On donne alors un critère nécessaire et suffisant pour que tout semi-flot dans une classe bien définie admette une section globale. Ce critère est facilement vérifiable en pratique. S'il existe une section globale, le complexe admet un feuilletage en graphes compacts tous homotopiquement équivalents et toute application de retour de tout semi-flot sur une section induit un automorphisme sur le groupe fondamental de la section. Réciproquement si o est un automorphisme quelconque du groupe libre Fn, on établit que le groupe suspension de o est le groupe fondamental d'un CW-complexe dynamique admettant un feuilletage en graphes compacts homotopiquement équivalents, de groupe fondamental isomorphe a Fn et tel que l'automorphisme induit soit conjugue a o dans out(Fn). La construction d'un tel CW-complexe dynamique est combinatoire. On étudie ensuite quelques propriétés topologiques et dynamiques liées a la combinatoire d'un CW-complexe dynamique et on fait notamment le lien avec les surfaces branchées dynamiques de Christy-Williams. Dans le dernier chapitre, on présente un algorithme fini pour la construction d'un template a la birman-williams associe au flot suspension d'un homéomorphisme pseudo-Anosov du disque troué.
2
Stein, Peter Vom. "Hochfrequenz Elektroneninjektoren für cw-Beschleuniger". Forschungszentrum Dresden, 2010. http://nbn-resolving.de/urn:nbn:de:bsz:d120-qucosa-30706.
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For today 's applications of superconducting accelerators like Linear Colliders and Free Electron Lasers (FEL) there is an increasing demand for high brightness beams. So get a high luminosity or high average laser beam power, the accelerator has to operate in cw mode or with a high duty factor. Therefore, new injectors are needed, delivering a low emittance beam with high average currents compatible to the acccelerator's macropulse structure. During the last 14 years the development of rf guns gained more and more importance for normal conducting accelerators. In this field they became the most advanced injector for high brightness beams. Nevertheless, because of the high rf losses they are, like normal conducting accelerators, limited to operation with low duty factors. At Forschungszentrum Rossendorf two concepts were developed to transfer the merits of the rf gun design to injectors with high duty factors. The first project is a thermionic 1.3 GHz rf gun with two decoupled cavities. A combination of rf and dc acceleration allows to operate the copper cavities at low gradients in cw mode. The design parameters of the injector are a low bunch charge of 1 pC with an emittance less than 1 π mm mrad. Because of the high repetiton rate of 1.3 GHz an average current of 400 µA can be reached. A test stand for the injector with a beamline for emittance, energy and bunch length measurement was built up. At average beam currents up to 80µA a normalized transverse emittance of 0.23 π mm mrad was measured. The measured energy width of 8 keV and the bunch length of 8 ps (FWHM) is in a very good agreement with the simulation results. The second project was realized in collaboration with the Budker Institute in Novosibirsk. The goal is the development of a photocathode rf gun with a superconducting cavity operating at high gradients in cw mode. A new design was worked out to solve the related rf and thermal problems. The beam dynamics of a superconducting 3½-cell rf gun were studied in detail by simulation. The resulting ernittance of 5.3 π mm mrad at a bunch charge of 200 pC opens a wide range of applications for high average power FELs. The fabrication of a half cell test cavity was finished in October 1997. First tests are scheduled for the middle of 1998 to prove the feasibility of our design.
3
Feng, Yen-Chun. "CW projectile tracking range analysis". Thesis, Monterey, California. Naval Postgraduate School, 1989. http://hdl.handle.net/10945/26957.
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4
Stein, Peter Vom. "Hochfrequenz Elektroneninjektoren für cw-Beschleuniger". Forschungszentrum Rossendorf, 1998. https://hzdr.qucosa.de/id/qucosa%3A21897.
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For today 's applications of superconducting accelerators like Linear Colliders and Free Electron Lasers (FEL) there is an increasing demand for high brightness beams. So get a high luminosity or high average laser beam power, the accelerator has to operate in cw mode or with a high duty factor. Therefore, new injectors are needed, delivering a low emittance beam with high average currents compatible to the acccelerator's macropulse structure. During the last 14 years the development of rf guns gained more and more importance for normal conducting accelerators. In this field they became the most advanced injector for high brightness beams. Nevertheless, because of the high rf losses they are, like normal conducting accelerators, limited to operation with low duty factors. At Forschungszentrum Rossendorf two concepts were developed to transfer the merits of the rf gun design to injectors with high duty factors. The first project is a thermionic 1.3 GHz rf gun with two decoupled cavities. A combination of rf and dc acceleration allows to operate the copper cavities at low gradients in cw mode. The design parameters of the injector are a low bunch charge of 1 pC with an emittance less than 1 π mm mrad. Because of the high repetiton rate of 1.3 GHz an average current of 400 µA can be reached. A test stand for the injector with a beamline for emittance, energy and bunch length measurement was built up. At average beam currents up to 80µA a normalized transverse emittance of 0.23 π mm mrad was measured. The measured energy width of 8 keV and the bunch length of 8 ps (FWHM) is in a very good agreement with the simulation results. The second project was realized in collaboration with the Budker Institute in Novosibirsk. The goal is the development of a photocathode rf gun with a superconducting cavity operating at high gradients in cw mode. A new design was worked out to solve the related rf and thermal problems. The beam dynamics of a superconducting 3½-cell rf gun were studied in detail by simulation. The resulting ernittance of 5.3 π mm mrad at a bunch charge of 200 pC opens a wide range of applications for high average power FELs. The fabrication of a half cell test cavity was finished in October 1997. First tests are scheduled for the middle of 1998 to prove the feasibility of our design.
5
Bačík, Martin. "Simulátor funkce FM-CW dálkoměru". Master's thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2012. http://www.nusl.cz/ntk/nusl-219875.
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This thesis describes design of Simulator FM-CW range finders. It is choosing the optimal method of realization and inform about basic properties of continuous working radar. The work includes an analysis of errors in real rangefinder and a numerical estimate of the maximum error in real devices. Contains detailed block diagram of simulator FM-CW range-finder and computer simulation of function generator frequency modulated signal, demodulator. Further work includes the complete construction documents for the preparation and implementation of basic functional verification
6
Platten, Richard John. "Proper group actions on CW-complexes". Thesis, Queen Mary, University of London, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.392890.
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7
Fujisawa, Hiroshi. "A cw 4-rod RFQ Linac". 京都大学 (Kyoto University), 1994. http://hdl.handle.net/2433/86446.
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8
Kuntzsch, Michael. "Optische Synchronisation am CW-Beschleuniger ELBE". Doctoral thesis, Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2015. http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-175133.
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Moderne Experimente in der Kurzzeitphysik erfordern eine hochpräzise Synchronisation der beteiligten Strahlungsquellen, um dynamische Prozesse und atomare Strukturen aufzulösen. Die Komplexität und räumliche Ausdehnung einer linearbeschleuniger-getriebenen Strahlungsquelle wie ELBE verlangt nach neuen Konzepten, um die anspruchsvollen Anforderungen zu erfüllen. Kernbestandteile der vorliegenden Arbeit sind die Konzeption, der Aufbau und die Inbetriebnahme eines gepulsten optischen Synchronisationssystems zur Verteilung eines Phasenreferenzsignals.
Dieses System bildet eine wesentliche Grundvoraussetzung für wissenschaftliche Experimente mit einer Auflösung im Bereich von wenigen zehn Femtosekunden. Darüber hinaus wurde der Prototyp eines Ankunftszeitmonitors am ELBE-Beschleuniger entwickelt und charakterisiert. Mit diesem Diagnoseelement wurden erstmals Messungen der Elektronenpulsankunftszeit mit einer Auflösung von wenigen Femtosekunden am ELBE-Strahl möglich. Die implementierte Datenanalyse erlaubt einzelpulsaufgelöste Messzyklen mit bisher unerreichter spektraler Bandbreite am kontinuierlichen (CW) Elektronenstrahl. Ferner wurde eine Methode zur Datenerfassung entwickelt, die unter Verwendung der Lockin-Technik besonders rauscharme Messungen hervorbringen kann.
Abschließend wurde der ELBE-Beschleuniger hinsichtlich Ankunftszeit und Energiestabilität umfassend untersucht. Dabei wurden die erweiterten Möglichkeiten, die ELBE als CW-Beschleuniger bietet, ausgeschöpft. Der Fokus lag besonders auf der spektralen Analyse der Störungen bei verschiedenen Kompressionszuständen der Elektronenpulse. Diese methodische Untersuchung wurde sowohl für den thermionischen Injektor als auch für die supraleitende Fotoelektronenquelle durchgeführt.
Die präsentierten Messergebnisse ermöglichen ein erweitertes Verständnis für die wirkenden Störmechanismen während der Elektronenpulspropagation und stellen den Ausgangspunkt für systematische Verbesserungen der Strahlqualität dar. Ein beschriebener Grundlagenversuch belegt, wie der ELBE-Elektronenstrahl in Zukunft aktiv stabilisiert werden kann, um die erforderliche Zeitauflösung zu erreichen. Intrinsische Strahlinstabilitäten können dadurch signifikant reduziert werden.
9
Hennes, Matthias. "Über Homotopietypen von vierdimensionalen Polyedern /". Bonn : [s.n.], 1991. http://bvbr.bib-bvb.de:8991/F?func=service&doc_library=BVB01&doc_number=005065761&line_number=0001&func_code=DB_RECORDS&service_type=MEDIA.
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10
Yetkil, Yasar Baris. "Design Of An Fm-cw Radar Altimeter". Master's thesis, METU, 2005. http://etd.lib.metu.edu.tr/upload/12606819/index.pdf.
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Frequency modulated continuous wave (FM-CW) radar altimeters are used in civil and military applications. Proximity fuses, automatic cruise control systems of cars, radar altimeter of planes are examples to these applications.
The goal of this thesis is to present a method for altitude determination using an FM-CW radar. For this purpose principles of radars and FM-CW systems are studied and related subjects are inspected. After this inspection, algorithms for altitude determination are evaluated. Consequently signal detection and processing methods are proposed to build an altitude determining algorithm. Also an analytical test environment for altitudes between 100 m and 4000 m is developed in computer as a result of researches. Test environment simulated the performance of altitude determining algorithm and FM-CW Radar Altimeter. The hardware is designed and implemented accordingly.
11
Mosaad, N. R. M. "Picosecond measurements with mode-locked CW lasers". Thesis, University of Strathclyde, 1987. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.382491.
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12
Al-Mashaabi, Fahad Saleh. "DC-excited cw CO₂ metal waveguide laser". PDXScholar, 1988. https://pdxscholar.library.pdx.edu/open_access_etds/3756.
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A novel design for a DC excited cw C02 metal waveguide laser has been developed in which a slotted hollow-cathode in a transverse discharge also doubles as a metal waveguide. This design has been implemented in a compact design that produces up to 1 watt of cw, 10.6 μm radiation. The discharge characteristics, laser gain and laser output has been studied as functions of various discharge parameters. The advantages of the new transverse discharge of the slotted hollow cathode geometry include low voltage, positive impedence and high optical gain. Overall efficiency is comparable with those of conventional longitudinal CO2 lasers. The output laser modes were very clean low order Gaussian modes.
13
Ardanuy, Della Antoni. "DSP-based CW lidars for clouds and aerosol". Doctoral thesis, Universitat Politècnica de Catalunya, 2020. http://hdl.handle.net/10803/670294.
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This thesis aims at exploring the limits of low peak-power, low-cost, all-semiconductor, compact lidars (laser radars) for range-resolved remote sensing of atmospheric aerosols and clouds. The systems investigated are based on laser diodes for emitter, avalanche photodiodes for the receiver, and digital signal processors for processing the returns from the atmosphere and the system control. The studied systems are built on the use of M-sequences and other derivated ones, which allows retrieving range-dependent information from the returning echoes, while having almost the same number of ones and zeros to maximize the transmitted average power for a limited peak power. The use of digital processors to generate the modulating sequences and to process the lidar returns allows for systems with agile reconfiguration capabilities and the use of very long sequences while keeping the processing time virtually negligible compared with the time employed to transmit the laser pulse-modulated output and receive the echoes from the atmosphere (the measuring time). The theorical developments are tested and demonstrated by the experimental results obtained with two lidar prototypes designed and build according the theoretical framework. The detection of cloud bases up to 8km with transmission peak powers of 125 mW in the near (almost visible) infrared (785 nm wavelength), with spatial resolution of 70 to 100 m and time resolution from 30 seconds to 4 minutes, has been achieved. Aerosols at lower altitudes are also observed in conditions of high aerosol load. In addition to further developments in low-cost lidar systems for detections of particles suspended in the atmosphere, the technical developments of this work pave also the way to the design of low-power systems por open path, range-resolved detection of gases, for example in industrial environments. After an introductory chapter, chapter 2 reviews the basic principles of lidar systems and focuses on continuous-wave systems with pseudorandom sequence modulation of the transmitted power and the constraints set by the requirement of a low peak-power transmitter. Chapter 3 reviews different types of power-modulating digital sequences that can be used, with the constraint of average 50% duty cycle, selects the best ones to be investigated in the experimental study, and unravels some of the issues associated to possible non-linear behavior of the photoreceiver. Chapter 4 presents the theoretical performance of the system, which is compared to a model that takes into account the technical constraints and non-idealities of the system building blocks. Chapter 5 sets out the complete design of the prototypes that have been built and tested, which are presented in chapter 6. Chapter 7 presents the tests and field results obtained with the prototypes built according to the design discussed in chapter 5. Chapter 8 presents the conclusions and outlines possible lines opened by the thesis work. Two appendices (chapter 9) develop further details on the detrimental effect of non-linear behavior in the receiver chain, and practical aspects of the alignment procedure between the lidar transmitter and the receiving optics.Aquesta tesi té com a objectiu explorar els límits dels lidars compactes (radars làser) de baixa potència de pic, baix cost, tot basat en semiconductors per a la detecció remota de núvols i aerosols atmosfèrics amb resolució en distància. Els sistemes investigats es basen en díodes làser per a l 'emissor, fotodíodes d'allau per al receptor i processadors digitals de senyal per a processar els retorns atmosfèrics i el control del sistema. Els sistemes estudiats es basen en l'ús de seqüències M i altres de derivades, el que permet recuperar la informació de la distancia dependent dels ecos del retorn, al mateix temps que té gairebé el mateix nombre d'uns i zeros per maximitzar la potència mitjana transmesa amb una potència de pic limitada. L'ús de processadors digitals per generar seqüències de modulació i retorns del lidar permet sistemes amb capacitat de canviar de configuració àgil i l'ús de seqüències molt llargues, mantenint el temps de processament pràcticament insignificant en comparació amb el temps dedicat a transmetre la sortida modulada del pols làser i rebre ecos de l'atmosfera (temps de mesurament). Els desenvolupaments teòrics són provats i demostrats amb resultats experimentals obtinguts amb dos prototips lidar dissenyats i construïts segons el marc teòric. La detecció de base de núvols fins a 8 km s'ha aconseguit amb potències de transmissió de 125 mW de potència en infraroig proper (quasi visible, 785 nm de longitud d'ona), amb resolució espacial de 70 a 100 m i resolució de temps de 30 segons a 4 minuts. Els aerosols en altituds més baixes també s'observen sota condicions de càrregues d'aerosols elevades. A més de nous desenvolupaments en sistemes lidar de baix cost per a la detecció de partícules en suspensió a l'atmosfera, els desenvolupaments tècnics d'aquest treball també preparen el camí per al disseny de sistemes de detecció de gasos de baix consum, amb resolució en distància, per exemple , en entorns industrials. Després d'un capítol introductori, el capítol 2 revisa els principis bàsics dels sistemes lidar i es centra en els sistemes d'ona contínua amb modulació amb seqüència pseudoaleatòries de la potència transmesa i les restriccions establertes per l'exigència d'un transmissor de potència de baixa potència de pic. El capítol 3 comentaris els diferents tipus de seqüències digitals per a la modulació de potència que es poden utilitzar, amb la restricció del cicle mitjà de treball del 50%, selecciona les millors per ser investigades en l'estudi experimental i desentranya alguns dels problemes associats amb el possible comportament no lineal del fotoreceptor. El capítol 4 presenta el rendiment teòric del sistema, que es compara amb un model que té en compte les limitacions tècniques i les no idealitats dels components bàsics del sistema. El capítol 5 estableix el disseny complet dels prototips que s'han construït i provat, que es presenten en el capítol 6. El capítol 7 presenta les proves i els resultats de camp obtinguts amb prototips construïts d'acord amb el disseny discutit en el capítol 5. El capítol 8 presenta les conclusions i s'esbossen possibles línies obertes pel treball de la tesi. Dos apèndixs (capítol 9) desenvolupen més detalls sobre l'efecte perjudicial del comportament no lineal en la cadena receptora i aspectes pràctics del procediment d'alineació entre el transmissor LIDAR i l'òptica receptora.
14
Lee, Jae Seung. "CW and pulsed TWTA phase noise reduction techniques /". For electronic version search Digital dissertations database. Restricted to UC campuses. Access is free to UC campus dissertations, 2005. http://uclibs.org/PID/11984.
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15
Kellerman, Robert A. "The design of an FM-CW proximity radar". Thesis, Stellenbosch : Stellenbosch University, 2004. http://hdl.handle.net/10019.1/50132.
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Thesis (MScEng) -- Stellenbosch University, 2004.ENGLISH ABSTRACT: The development of a small, cost effective short range FM-CW radar as well as the design and optimization of a double helix antenna is discussed. The FM-CW radar operates at Sband (2450 - 2550 MHz) and is limited at a maximum transmitted power of 5 dBm. The system is required to detect reflections from objects up to a 30 m range. This was made possible largely by the effective high gain antenna design and improved system isolation between the transmitted and received signals. The complete design process from fundamental requirements, through various simulations and system analysis to the final electronic circuit is discussed. The design was also built and measured in the laboratory and initial field measurements were taken. The following aspects were considered: Relation between the beat frequency and various FM-CW radar system parameters based on the theory, preliminary measurements and simulations. Radar component assessment and design. Design of a low cost Lange coupler that isolates the system's transmit and receive signals, which operates as a 90° hybrid and is used to feed a dual-fed circularly polarized patch antenna. A circularly polarized patch antenna and double helix antenna were designed, built and measured in an anechoic chamber. The antennas were implemented in the final radar system and compared on the basis of their contribution to the system's performance. Integrating the final radar system on a circular 60 mm diameter PCB with a double helix antenna mounted on top. The final radar system is able to measure range up to 40 m and meets all the design requirements. The signal processing of the measured beat frequency, however, can be taken further.
AFRIKAANSE OPSOMMING: Die ontwikkeling van 'n klein, koste effektiewe kort-afstand FM-CW radar, sowel as die onwerp en optimalisering van 'n dubbele heliks-antenna word bespreek. Die FM-CW radar werk by S-band (2450 - 2550 MHz) en is beperk tot 'n maksimum uitsaaidrywing van 5 dBm. Van die stelsel word vereis om weerkaatsings van voorwerpe tot op 'n afstand van 30 m waar te neem. Dit is grootliks moontlik gemaak deur die hoë aanwins antenna-ontwerp en verbeterde isolasie tussen die stelsel se uitsaai- en ontvangseine. Die volledige ontwerpsproses van die fundamentele vereistes af tot die finale elektroniese stroombaan word bespreek. Verskeie simulasies andstelselanalises is gebruik om die finale FM-CW radar te realiseer. Die ontwerp is vervolgens in die laboratorium gebou en gemeet en aanvangsveldmetings is geneem. Die volgende aspekte is in nagevors: Verband tussen die puls-frekwensie en verskeie FM-CW radar stelselparameters gebaseer op die teorie, inleidende metings en simulasies. Ontleding van verskeie radarkomponente en -stelselontwerp. Ontwerp van 'n lae koste Lange-koppelaar met die doelom die stelsel se uitsaai- en ontvangseine te isoleer. Die Lange-koppelaar dien as 'n 90° hibriede wat gebruik word om 'n dubbele-voer sirkulêr gepolariseerde mikrostrookantenna aan te dryf. Verder is 'n sirkulêr gepolariseerde mikrostrook-antenna en 'n dubbele heliksantenna ontwerp en opgemeet in 'n anarqoïese kamer. Beide antennas is geïmplimenteer in die finale radarstelsel en is vergelyk op grond van hulle rol in die stelsel se funksionering. Die finale stelsel is geïntegreer en gebou op 'n ronde 60 mm deursnit PCB met 'n dubbele helix-antenna bo-op gemonteer. Die finale radarstelsel kan afstand tot op 40 meter bepaal en voldoen aan al die gestelde vereistes. Seinverwerking van die gemete puls-frekwensie kan nog verder ontwikkel word.
16
Carhuapoma, Lopez Edith Milagros. "Variedades topológicas homtópicamente equivalente a un CW _ Complejo". Bachelor's thesis, Universidad Nacional Mayor de San Marcos, 2014. https://hdl.handle.net/20.500.12672/10244.
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Publicación a texto completo no autorizada por el autorDemuestra que toda variedad topológica de hausdorff con base numerable tiene el mismo tipo de homotopía de un CW Complejo. Los CW Complejos son sin duda lo más importante, y juegan un papel preponderante, sobre todo en la topología algebraica. Muchas de variedades tienen la estructura de un CW Complejo. Una de sus características más importante las menciona John Milnor, que en el año 1959 publica un artículo en el que establece que un espacio tiene el tipo de homotopía de un CW Complejo si es dominado por un CW Complejo numerable. Entonces, es de interés en el presente trabajo probar si toda la variedad topológica de Hausdor con base numerable es del tipo de homotopía de un CW Complejo. Para esto, hemos dividido la presente investigación en tres capítulos, con la intención de desarrollar con más detalle la propuesta
Tesis
17
Fuchs, Michal. "Měření trajektorie malých cílů pomocí sítě CW radarů". Doctoral thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2012. http://www.nusl.cz/ntk/nusl-233570.
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This dissertation is focused on target trajectory identification using CW radar sensor network measuring. An omni-directional radar based on single mixing is considered for measurement in ballistic tunnel, where information about direction of target approaching is a priory known. Applied experimental radar network setup with system controller and acquisition units is demonstrated. Mathematical models and optimized structures have been developed for fitting of system parameters and presented in the theoretical part. The second part is aimed to the multi-trajectory identification. New methodical techniques of this work consist in identification of the points of the closest approach with V model function and utilizing gradient methods for path identification.
18
Hoole, Jonathan G. "Implementation of a Low-cost FM-CW Radar". Thesis, Link to the online version, 2008. http://hdl.handle.net/10019/1333.
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Stringham, Craig Lee. "Developments in LFM-CW SAR for UAV Operation". BYU ScholarsArchive, 2014. https://scholarsarchive.byu.edu/etd/5587.
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Opportunities to use synthetic aperture radar (SAR) in scientific studies and military operations are expanding with the development of small SAR systems that can be operated on small unmanned air vehicles (UAV)s. While the nimble nature of small UAVs make them an attractive platform for many reasons, small UAVs are also more prone to deviate from a linear course due autopilot errors and external forces such as turbulence and wind. Thus, motion compensation and improved processing algorithms are required to properly focus the SAR images. The work of this dissertation overcomes some of the challenges and addresses some of the opportunities of operating SAR on small UAVs. Several contributions to SAR backprojection processing for UAV SARs are developed including: 1. The derivation of a novel SAR backprojection algorithm that accounts for motion during the pulse that is appropriate for narrow or ultra-wide-band SAR. 2. A compensation method for SAR backprojection to enable radiometrically accurate image processing. 3. The design and implementation of a real-time backprojection processor on a commercially available GPU that takes advantage of the GPU texture cache. 4. A new autofocus method that improves the image focus by estimating motion measurement errors in three dimensions, correcting for both amplitude and phase errors caused by inaccurate motion parameters. 5. A generalization of factorized backprojection, which we call the Dually Factorized Backprojection method, that factorizes the correlation integral in both slow-time and fast-time in order to efficiently account for general motion during the transmit of an LFM-CW pulse. Much of this work was conducted in support of the Characterization of Arctic Sea Ice Experiment (CASIE), and the appendices provide substantial contributions for this project as well, including: 1. My work in designing and implementing the digital receiver and controller board for the microASAR which was used for CASIE. 2. A description of how the GPU backprojection was used to improved the CASIE imagery. 3. A description of a sample SAR data set from CASIE provided to the public to promote further SAR research.
20
Kemp, Matthew James. "A FM-CW microwave radar for rainfall applications". Thesis, University of Iowa, 2012. https://ir.uiowa.edu/etd/2914.
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Previous works have validated the concept of a microwave rain gauge that operates as follows. With a microwave Doppler motion sensor, the Doppler shift created by falling rain drops is measured. One can then relate the corresponding fall velocity to rain rate. However, the available Doppler motion sensors are lacking in several aspects. Here we address the important electronic design and signal processing considerations related to a microwave-based rain gauge.
21
Haralambous, Yannis. "Coformalité modérée et formalité des CW-complexes de dimension finie". Lille 1, 1990. https://hal.archives-ouvertes.fr/tel-02099853.
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Introduite par w. G. Dwyer en 1979, la theorie de l'homotopie moderee permet de prendre en compte une partie de la torsion des groupes d'homotopie, tout en conservant les techniques de l'homotopie rationnelle. Le but de ce travail est d'etudier ce que deviennent, dans ce contexte, les deux notions de formalite et coformalite existant en homotopie rationnelle. La premiere partie consiste en l'etablissement d'un outil adapte a la situation: une theorie de perturbation en algebres de lie differentielles sur un sous-anneau de q, contenant 1/2 et 1/3. La non-coformalite moderee peut alors etre mise en evidence par l'existence de perturbations; par exemple, certaines suspensions ne sont pas coformelles moderees. L'etude de la formalite est menee pour les cw-complexes de dimension finie, non pas sur un systeme d'anneaux, mais sur un anneau r, comme le fait d. Anick. Lorsque l'espace est sans torsion homologique, nous obtenons une situation analogue a celle du cadre rationnel: les obstructions a la r-formalite sont des classes de cohomologie de harrison; la r-formalite se lit sur la differentielle du r-modele d'adams-hilton. Pour demontrer ces resultats nous generalisons d'abord un theoreme de barr reliant les cohomologies de hochschild et de harrison. Nous fournissons egalement une premiere approche a l'etude, en algebres de lie differentielles, de la r-formalite des espaces avec torsion homologique
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Brügmann, Oliver. "Aufbau eines cw-, Puls-EPR-Spektrometers bei 180 GHz". [S.l. : s.n.], 2003. http://deposit.ddb.de/cgi-bin/dokserv?idn=969668880.
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Bartz, Ulrich [Verfasser]. "Untersuchung und Optimierung eines CW-RFQ-Prototypen / Ulrich Bartz". Aachen : Shaker, 2014. http://d-nb.info/1051574390/34.
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Silvestre, Flávio Carlos da Silva Rodrigues. "Detetor digital síncrono de sinal CW baseado em FPGA". Master's thesis, Universidade de Aveiro, 2013. http://hdl.handle.net/10773/11805.
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Mestrado em Engenharia de MateriaisA propagação de sinais acima de 10 GHz na atmosfera sofre de atenuação e despolarização devido à presença de hidrometeoros. A caracterização e o modelamento destas contrariedades exige longas campanhas de medição as quais são efectuados usando receptores dedicados que monitorizam o sinal CW de elevada pureza espectral radiado por satélites geo-estacionário. Os sinais a medir são habitualmente dois, o denominado copolar (recebido com polarização original) e o crosspolar (polarização ortogonal). A medição da amplitude permite obter a magnitude de atenuação atmosférica, a qual é importante para saber durante quanto tempo do ano uma ligação de satélite estará indisponível. A medição do tipo de sinais aqui pretendido é sempre problemático pois o sinal recebido apresenta um valor de CNR muito reduzido, algum espalhamento espectral e deriva de frequência. Os métodos de deteção coerente por PLL ou FLL são preferidos neste tipo de aplicações e apresentam uma gama dinâmica superior mas por outro lado a sua implementação no domínio analógico pode ser bastante díficil. De modo a contornar a inflexibilidade dos métodos analógicos recorreu-se ao conceito de Software Defined Radio (SDR) que procura tratar os sinais de rádio, tanto quanto possível, no domínio digital. Deste modo resultou a ideia para o trabalho desta dissertação, que consistiu na elaboração de um pequeno módulo capaz de detectar digitalmente o sinal proveniente de satélite a uma frequência intermédia (IF) e com recurso a uma FPGA, adicionalmente os resultados da detecção são enviados para um computador hospedeiro. Com vista à conceptualização do projecto é feita uma caracterização do sinal a detectar e são apresentados alguns métodos de detecção dando-se enfâse aos que fazem uso de malhas de sincronização. Seguidamente é feita uma descrição da placa de conversão analógico-digital construída e da arquitectura do detector síncrono realizado na FPGA: etapas de filtragem, decimação e especificação dos parâmetros de loop. É ainda descrito o processo de transferência de dados para o PC via controlador USB. Por fim alguns resultados utilizando um gerador RF para sintetizar o sinal de entrada são apresentados e analisados. Foi concluído que o detector adquire o sincronismo para sinais acima de -60 dBm, o que apesar de ser uma situação onde o ruído é muito reduzido, deixa boas indicações para testes efetuados em ambiente real.
Earth-Satellite propagation channel modeling requires extensive measurement campaigns at as many sites, frequencies and link parameters as possible. The campaigns are made by estimating the received amplitude of a beacon CW signal radiated from a satellite using beacon receivers. The receiver measures the signal with the same polarization as the radiated one (copolar) and often the orthogonal (crosspolar) that carries additional information on the channel. As the carrier to noise ratio (CNR) is low a coherent detection is often used and requires the use of tracking loops whose implementation in the analogue domain is harsh. The use of digital radio hardware and/or software defined radio techniques to handle the tracking and detection is now being used: the down conversion is made within a FPGA, processed, and the data is moved to a host computer for further software processing. A stand-alone detector unit combining the frequency down conversion and detection in a single board and delivering the Cartesian two channel detected amplitudes to a host PC is described. The advantages would be a general purpose board that could handle, with no more hardware or software developments, measurement of beacon signals in a wide IF input range making also easier the analogue design of the preceding beacon receiver hardware. Some preliminar results of the developed detector with a clean signal provided by a waveform generator are presented and analysed. It was concluded that the detector can achieve lock with signals as low as -60 dBm in absense of phase noise, which leaves good indications to a real world detection scenario. The dissertation ends with some ideas for improvement and future work such as the utilization of frequency locked loops.
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Sahebkar, Khorasani Elham. "A reasoning methodology for CW-based question answering systems /". Available to subscribers only, 2008. http://proquest.umi.com/pqdweb?did=1594491071&sid=12&Fmt=2&clientId=1509&RQT=309&VName=PQD.
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Eryilmaz, Ertan. "Design And Construction Of A Cw Mode Nd:yag Laser Prototype". Master's thesis, METU, 2004. http://etd.lib.metu.edu.tr/upload/12605521/index.pdf.
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In this thesis a theoretical background of Nd:YAG lasers has been
presented and key parameters of a design have been stated. Both
pulsed mode and CW mode designs have been madea 500mJ xenon flash lamp has been investigated as the pulsed light source and a 500W tungsten halogen lamp has been used as the continuous light source for optical pumping. Closed cooling system has been constructed. De-ionized water has been used as coolant. The goal has been acomplished by constructing a CW mode prototype. The output power has been calculated. Dependence of output power to the reflectivity of output coupler is simulated and optimum reflectivity is calculated. Theoretical emission bands of Nd:YAG have been observed experimentally.
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Tucker, Richard James. "A cw-ENDOR investigation of metal-ligand interactions in solution". Thesis, Cardiff University, 2005. http://orca.cf.ac.uk/55155/.
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Electron Nuclear DOuble Resonance (ENDOR) spectroscopy has been employed in this Thesis to study a range of paramagnetic metal-ligand complex systems. The investigations focussed on the observation of conformational changes, solvatochromic effects and weak diastereomeric interactions of the complexes in frozen solution. Using a combination of angular selective ENDOR spectroscopy and DFT calculations, the structure and conformations of the Vlv=0(acac)2 complex in coordinating and non-coordinating solvents was examined. In the non-coordinating solvent (CD2CI2) the complex was found to adopt the expected square pyramidal structure, where the VOH lg distances and coordinates obtained by DFT and ENDOR were in excellent agreement with each other confirming the expected structure. More importantly, in coordinating solvents (such as pyridine) two different stereoisomers of the resulting Vlv=0(acac)2(C5D< N) adduct, which differed in energy by only 3 kJmol"1, were readily identified and discriminated by ENDOR (PCCP 2002). Subtle changes to metal-ligand structures by solvatochromic effects were also examined using Vlv=0(salen) in both coordinating (DMF) and non-coordinating (CD2CI2) solvents. In the non-coordinating solvent (CD2CI2), the expected square pyramidal symmetry of the V=0 ion above the NNOO plane of the ligand was confirmed both by ENDOR and DFT. However, in the coordinating solvent (DMF), a subtle perturbation from square pyramidal structure was observed suggesting than DMF coordinated trans to the vanadyl oxo-ligand, pulling Vlv=0 back into the ligand plane. This was evidenced through analysis of the VO....H j{j distances determined by ENDOR and confirmed by DFT (Chem. Phys. Lett. 2003). ENDOR was also used to explore the weak enantioselective binding between vanadyl based chiral salen complexes (abbreviated to VO(Jacobsen) ) and chiral propylene epoxide. Differences in epoxide binding by enatiomers of the complex was evidenced by changes to the 'H epoxide derived peaks in the ENDOR spectra. These changes were assigned to the small structural differences between the diastereomeric metal-epoxide adducts. Simulation of the spectra revealed differences in the VO...lHepoxjde distances for the diastereomeric pairs, which was confirmed by DFT. While the epoxide molecule was very weakly coordinated, ENDOR measurements of the racemic complex in racemic epoxide nevertheless indicated the preferential coordination of the /- VO(Jacobsen) to /-epoxide. This demonstrates the unique power of the ENDOR technique to resolve weak chiral interactions for which EPR spectroscopy alone lacks sufficient resolution (./ACS 2004). Finally, the diastereomeric interactions between chiral amines and copper based chiral salen complexes (abbreviated to Cu(Jacobsen) ) was investigated, as a comparison with the previous weak interactions in the VO(Jacobsen)-epoxide case. Diastereomeric discrimination was once again evidenced by ENDOR. The slight differences in the Cu-amine distances, constrained by the chirality of the anchoring site, resulted in subtle difference in the spin densities to the ligand nitrogens, which was detected in the ENDOR experiment.
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De, Wit W. M. "Linearisation of an FM-CW 94.5 GHz millimeter-wave radar". Thesis, Stellenbosch : University of Stellenbosch, 2006. http://hdl.handle.net/10019.1/2858.
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Thesis (MScEng (Electrical and Electronic Engineering))--University of Stellenbosch, 2006.The topic of millimeter wave radar systems is introduced. These radars are used in a wide range of applications in both the aviation and automotive field due to the resolution advantages which MMW systems have above their counterparts. MMW components are studied and characterised to improve on an existing linearisation technique. Different possible linearisation techniques are discussed and compared to choose the best possible technique for this application. This technique was developed and implemented in the existing system.
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Aprile, Nathália Pio. "Absorção fotoinduzida de onda contínua (CW-PIA) em polímeros semicondutores". Universidade de São Paulo, 2015. http://www.teses.usp.br/teses/disponiveis/18/18158/tde-19022016-013827/.
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Existem algumas técnicas destinadas ao estudo das características fotofísicas de materiais orgânicos ou dispositivos eletrônicos e optoeletrônicos a base de semicondutores orgânicos. A exemplo disso, a técnica de espectroscopia de absorção fotoinduzida de onda contínua (Continuous Wave Photoinduced Absorption/cw-PIA) apresenta grande sensibilidade como método destinado ao estudo dos processos eletrônicos envolvendo espécies excitadas de vida longa. Esta técnica emprega dois feixes ópticos distintos, um para excitação da amostra e outro (feixe de prova) para investigar os estados excitados remanescentes em amostra após bombeio óptico. O presente trabalho tem como objetivo a construção, desenvolvimento e caracterização de um aparato experimental para espectroscopia cw-PIA. A montagem bem sucedida da técnica foi testada em filme do polímero semicondutor P3HT, em filme de blenda (1:1) de P3HT/PCBM (comumente utilizada como camada ativa em células solares orgânicas) e em filmes automontados camada-a-camada (LbL) do tipo doador-aceitador de carga (P3KHT/P6N), sendo que a molécula P6N foi sintetizada pelo Grupo de Polímeros Bernhard Gross do IFSC-USP. Os filmes LbL de P3KHT/P6N, em comparação aos filmes blenda de P3HT/PCBM, demonstraram uma eficiência maior quanto a geração de portadores de carga com tempo de vida longo.There are some techniques for the study of photophysical characteristics of organic materials or electronic and optoelectronic devices based on organic semiconductors. For example, the technique of continuous wave photoinduced absorption spectroscopy (cw-PIA) is a highly sensitive method for the study of the electronic processes involving long-lived excited species. This technique uses two distinct optical beams, one for sample excitation and another for probing the excited states remaining in the sample after optical pumping. The present work aims at the construction, development and characterization of an experimental apparatus for cw-PIA spectroscopy. The successful implementation of the technique was tested in a film of the semiconducting polymer P3HT and of the blend (1:1) P3HT/ PCBM (usually employed as active layer in organic solar cells), and also in a Layer-by-Layer (LbL) film of donor-acceptor molecules P3KHT/P6N, where the P6N molecule has been synthesized by Polymer Group Bernhard Gross at IFSC- USP. The comparison between P3KHT / P6N LbL film and the blend P3HT/PCBM has demonstrated higher charge carrier generation efficiency (with long lifetime) for the LbL film.
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Yang, Wu. "Traffic Surveillance Using Low Cost Continuous Wave (CW) Doppler Radars". Wright State University / OhioLINK, 2012. http://rave.ohiolink.edu/etdc/view?acc_num=wright1347404224.
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Isaacson, Adam Rhett. "A 500kHz-5MHz CW stepped frequency borehole tomographic imaging system". Master's thesis, University of Cape Town, 2001. http://hdl.handle.net/11427/5203.
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Includes bibliography.This dissertation involves a study of Cross-Borehole Tomography. The mathematical physical models of the Radon Transform are reviewed. The entire Cross-Borehole Tomographic process is simulated, based on these physical models of the Radon Transform. The system specifications for the final design are based on the results from the simulation. Finally, the final design is built, and tested. The phase yields a better quality of image reconstruction when compared to amplitude, and hence a coherent system is a good choice. The system is frequency to frequency coherent for the entire transmit frequency range, which satisfies the main aim of this dissertation.
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Suchla, Engelbert Peter [Verfasser]. "L²-Invariants for Self-Similar CW-Complexes / Engelbert Peter Suchla". Göttingen : Niedersächsische Staats- und Universitätsbibliothek Göttingen, 2020. http://d-nb.info/1221367811/34.
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Hajiaghajani, Kazem 1955. "Design of an optimum driver circuit for CW laser diodes". Thesis, The University of Arizona, 1992. http://hdl.handle.net/10150/291359.
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A poorly designed drive circuit leads at best to unstable optical output power and/or frequency and at worst to permanent damage to the laser diode. Thermal stress on the laser diode junction and noise from various sources degrade the diode's performance and may result in its damage, and transients may destroy the laser diode outright. This thesis explores all failure mechanisms of a laser diode, and offers solutions to prevent and/or controll them. General drive circuit considerations and requirements of various demanding applications of a CW laser diode are discussed. Finally, a fully functional drive circuit is presented.
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Moon, Kyra Michelle. "Windowed Factorized Backprojection for Pulsed and LFM-CW Stripmap SAR". BYU ScholarsArchive, 2012. https://scholarsarchive.byu.edu/etd/3485.
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Factorized backprojection is a processing algorithm for reconstructing images from data collected by synthetic aperture radar (SAR) systems. Factorized backprojection requires less computation than conventional time-domain backprojection with little loss in accuracy for straight-line motion. However, its implementation is not as straightforward as direct backprojection. Further, implementing an azimuth window has been difficult in previous versions of factorized backprojection. This thesis provides a new, easily parallelizable formulation of factorized backprojection designed for both pulsed and linearly frequency modulated continuous wave (LFM-CW) stripmap SAR data. A method of easily implementing an azimuth window as part of the factorized backprojection algorithm is introduced. The approximations made in factorized backprojection are investigated and a detailed analysis of the corresponding errors is provided. We compare the performance of windowed factorized backprojection to direct backprojection for simulated and actual SAR data.
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McCloskey, Daniel John. "Population genetics of HLA class I-A, -B and -Cw polymorphism". Thesis, Queen Mary, University of London, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.271337.
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Cooper, G. S. "Pulsed and CW waves in nonlinear optical fibre and planar waveguides". Thesis, University of Salford, 1988. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.381647.
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Reese, Annabelle Wey. "Analysis of CW-EPR spectra and the internal dynamics of DNA /". Thesis, Connect to this title online; UW restricted, 1996. http://hdl.handle.net/1773/8569.
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Zaugg, Evan C. "Generalized Image Formation for Pulsed and LFM-CW Synthetic Aperture Radar". BYU ScholarsArchive, 2010. https://scholarsarchive.byu.edu/etd/2489.
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Approximations made in the traditional signal model for synthetic aperture radar (SAR) processing cause defocusing of the radar images when the system operates under conditions where the approximations lose validity. This dissertation investigates a number of these approximations and presents algorithmic improvements based on generalizations of the approxmations of the SAR signal model. These improvements result in better focused imagery from SAR systems with varied designs and parameters. Among the advancements presented is the development of a generalized chirp-scaling algorithm and a generalized frequency scaling algorithm to address the problems caused by approximations based on a Taylor series expansion of the SAR signal for both pulsed SAR and linear frequency modulated continuous wave (LFM-CW) SAR systems. These generalized algorithms extend the ability of frequency-domain algorithms to process SAR data from systems with a low frequency, a wide beamwidth, and a large bandwidth. Image formation algorithms are developed that account for the continuous platform motion and compensate for translational position errors due to the continuous non-ideal motion of real-world LFM-CW SAR systems, including a backprojection algorithm that does not rely upon the traditional stop-and-go approximation for platform motion.
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Lyubenova, Sevdalina. "Metalloproteins and protein-protein complexes investigated by CW and pulsed EPR spectroscopy". [S.l.] : [s.n.], 2006. http://deposit.ddb.de/cgi-bin/dokserv?idn=980698812.
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Shepherd, Sara. "Use and development of a CW titanium sapphire laser for nonlinear optics". Thesis, University of St Andrews, 1994. http://hdl.handle.net/10023/9931.
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A cw titanium sapphire laser pumped by an argon ion laser was used for experiments both in second harmonic generation using a non-linear crystal and for sum-frequency generation in an atomic vapour. In addition the laser was stabilised to sub-MHz levels. Using a crystal of potassium niobate (KNbO₃), the Ti:sapphire laser was frequency doubled over the range 860nm-905nm using an intracavity scheme. The crystal was temperature tuned to achieve near non-critical phase-matching and powers of up to 50mW were obtained, with a constant conversion efficiency per Watt over the doubling range. The thermal properties of potassium niobate in frequency doubling were examined and the effect of the crystal on the ring cavity during temperature tuning was investigated. The laser cavity was frequency stabilised using a 'side of fringe' locking scheme with a confocal Fabry-Perot etalon as the reference discriminator. The cavity length control elements were two Brewster-angled tilt plates and a piezo mounted mirror. Using this scheme the frequency noise was reduced from tens of MHz to 550kHz. Methods of obtaining a 30GHz frequency scan were also evaluated and an experimental 10GHz scan achieved. It was concluded that only dither and lock schemes are good enough to achieve reliable 30GHz scans. Using both a Ti:sapphire laser and a dye laser, two contrasting schemes for sum-frequency generation in sodium vapour were investigated, in which a magnetic field was used to break the symmetry of the medium. Using one of these resonantly enhanced routes, powers of 17μW in the UV were obtained from a classically 'forbidden' quadrupole transition. The effects of phase-matching on each of the transitions was examined in detail, and it was found that in general there are at least six factors which affect the phase-matching behaviour of the frequency mixing scheme. It was also found that on the route which had two sources of dispersion there was a significant distortion of the output line profiles at high temperatures due to a variation in phase-matching across the line profile itself.
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Bontemps, Patrick. "CW and envelope pulse propagation in optical non-Kerr and magnetic media". Thesis, University of Salford, 2009. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.484184.
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Bolton, David Robert. "Circuits and systems for CW and pulsed high-field electron spin resonance". Thesis, University of St Andrews, 2006. http://hdl.handle.net/10023/7104.
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This thesis is concerned with the design and realisation of components for a new state of the art 94GHz Electron Spin Resonance (ESR) spectrometer capable of operating in both pulsed and CW modes. The complete spectrometer is designed to provide phase coherent 1kW peak power sub-nanosecond π/2 pulses having variable duration and repetition rate. The mm-wave response of a paramagnetic sample to these pulses is detected with a superheterodyne detector. Such a system would offer a step change in performance, promising unprecedented resolution and sensitivity. These aims should be compared with the performance of commercial (Bruker) instruments capable of delivering 200mW 30ns π/2 pulses. For this type of system, both the long term (thermal) and short term (phase) stability of oscillators and sources employed are extremely important. Consideration of phase noise, frequency, tunability and power output shows that multiplied sources offer substantial benefits compared to fundamental sources. A delay line discriminator method of phase noise measurement, suitable for use with the low frequency oscillators is described and implemented. This is extended to 94GHz using a down convertor with a quasi-optically stabilised Gunn oscillator. These tools are used to select an optimum oscillator-multiplier combination to produce a low noise 94GHz source. Anew method of pulse generation, which has produced +23dBm peak power 250ps rectangular and 115ps Gaussian envelope phase coherent pulses, is described. These are believed to be the shortest phase coherent pulses at 94GHz available. This system will be used to provide ns pulses suitable for amplification to 1kW using a Klystron amplifier. A heterodyne detector has been constructed which employs the same oscillator/multiplier techniques identified above to produce the required local oscillator signal. It is demonstrated that by careful consideration of multiplication factors a system employing one variable and one fixed oscillator allows all the signals required in the spectrometer to maintain phase coherence. It is demonstrated that the complete demodulator responds to pulses on a ns time scale and has a noise temperature of 737K.
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Shi, Lishen. "Coherent optical code division multiple access (CDMA) network employing CW semiconductor lasers". Thesis, University of Strathclyde, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.273787.
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Gibson, Graham Martin. "Continuously frequency-tunable CW optical parametric oscillators and their application to spectroscopy". Thesis, University of St Andrews, 1999. http://hdl.handle.net/10023/14950.
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This thesis describes the development and applications of single-frequency, continuously tunable, continuous-wave (cw), optical parametric oscillators (OPOs). Two doubly-resonant OPOs (DROs) are presented, one providing tunable light around 1?m, the other specifically designed as a spectroscopic source for methane near 1649nm. Once stabilised, the frequency-selective nature of the DRO ensures operation on a single mode-pair without the need for additional intracavity frequency-selective components. Both DROs are smoothly tunable by smoothly tuning the pump laser. The 1mum DRO is based on a bulk KTP crystal cut for near-degenerate, type-II, critical phase-matching (theta= 90°, ϕ = 37°). Angle tuning the crystal provides coarse tuning of the output frequencies over a range of ~50nm. Small perturbations to the OPO cavity is sufficient to cause a systematic mode-hop and provides a method of tuning across the phase-matching bandwidth (~0.5THz). This DRO is demonstrated as a spectroscopic source by recording the absorption spectrum of cesium molecules near 1050nm. The DRO as a potentially compact source of tunable light is demonstrated by using a frequency-doubled microchip laser as the pump source. The output consists of a single pair of signal and idler modes even when using a multilongitudinal-mode pump laser. Smooth tuning of the output frequencies is achieved by temperature tuning the pump laser. The 1.65mum DRO is based on periodically poled KTiOPO4 (PPKTP). The suitability of PPKTP for cw OPOs was first assessed by a difference frequency generation experiment from which the effective d33 coefficient was estimated to be ~5mum/V. The idler wavelength is coarsely tuned at a rate of 0.73nm/°C by varying the crystal temperature. A combination of computer modelling and experimental observation is used to study the dynamic behaviour of a DRO. The numerical model calculates the time required for the OPO to build-up from the parametric fluorescence and is in excellent agreement with experimental observations.
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Rodrigues, Emanuel Filipe de Ornelas. "Software GNU radio para detector digital de sinais CW com baixa SNR". Master's thesis, Universidade de Aveiro, 2009. http://hdl.handle.net/10773/9452.
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Mestrado em Engenharia Electrónica e TelecomunicaçõesCom a constante evolução das tecnologias de comunicação por satélite, surge a necessidade de expandir a gama de frequências utilizadas quer para melhorar a qualidade dos serviços existentes como disponibilizar novos tipos. Neste âmbito foi proposta uma campanha de medição de um sinal de beacon transmitido pelo TDP5 a bordo do AlphaSat. Esta campanha trata-se de um passo essencial para a caracterização de canais de transmissão na banda Q-V em vários pontos da Europa. O satélite será lançado em 2012 e irá transmitir um sinal beacon a 39:4GHz. Pelo facto de o desenvolvimento de um receptor implementado inteiramente em hardware ser muito dispendioso, propõe-se nesta tese a substituição de parte dos componentes por um sistema SDR. Este será baseado no equipamento USRP e software GNU Radio, o qual fará o controlo de um frontend que converte a frequência para 10:7MHz, a sintonização, análise e registo do sinal, assim como o seguimento em frequência deste ao longo do tempo. Esta solução apresenta custos mais reduzidos e maior flexibilidade nas funções que pode desempenhar. São apresentados os métodos de programação de um sistema desta natureza, a interface de utilizador para configuração do receptor e os testes de funcionamento simulando as condições de recepção esperadas.
As the satellite communication develop the need to expand the available frequency range, in order to improve the existent services and offer new ones, have risen. In this matter a campaign to monitor a beacon signal transmitted by the TDP5 onboard of the AlphaSat was was proposed. This satellite is expected to launch in 2012 and will be transmitting at 39:4GHz. Due to the fact that the implementation of an hardware-only solution is costly, we hereby present an option to exchange part of the circuitry for an SDR system. It will be based on the USRP and GNU Radio platform, which will control the basic frontend downconversion to 10:7MHz, the signal tuning, analysis and logging, as well as the dynamic tuning to follow frequency drifts. This solution presents lower development costs and increased flexibility in functionality. It is presented the programming method for such system, the user interface to configure the beacon receptor and tests simulating the expected real life conditions.
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Olsson, Fredrik. "Estimating the fuel ion dilution in fusion plasmas using neutron emission spectrometry". Thesis, Uppsala universitet, Institutionen för fysik och astronomi, 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-227653.
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Fusion power has the potential to produce clean and safe energy that can contribute significantly to the worlds energy system. The road to this promising energy resource has been long, but with one of the biggest projects in the scientific area that is now on going, a fusion project called ITER, the end of the road is ahead of us. Experiments with a new reactor wall are now in progress at the fusion test reactor JET in Oxford, England. The experiment is a pre study of a possible reactor wall for the new fusion reactor ITER in Cadarache in Provence-Alpes-Côte-d'Azur, France. The ITER like reactor wall (ILW) contains Beryllium and has theoretically favourable properties for achieving better reactor conditions, compared to the old Carbon based wall (CW). One reason for changing the wall is to decrease the fuel dilution, i.e. amount of particles that the reactor wall contributes to the fusion plasma. This is an important factor to minimize; 1% of fuel dilution with Carbon will cause a loss in power up to 12%, while the corresponding value for Beryllium is 8%. For Deuterium fuelled plasmas at JET, the fuel dilution can be quantified by the ratio of the Deuterium and electron densities, nd/ne. In this work, nd/ne is estimated using data from the neutron emission spectrometer TOFOR, along with measurements of the electron density (ne) and temperature (Te). In this report it is investigated how sensitive these fuel dilution measurements are to uncertainties in the measurements of ne and Te. The fuel dilution measurements changed relatively in a span of 10% to 23% when changing Te and ne with 10% in the fuel dilution model. To determine the differences in fuel dilution between the Carbon and ITER like reactor wall, a comparison has to be made between the old reactor wall and the new ILW. To do this, similar plasma scenarios need to be represented during fusion discharges with both walls. In this report, JET’s database is searched through using different search criteria, in order to enable a fair comparison between the walls. The comparison showed a tendency of lower fuel dilution, i.e. cleaner plasmas, for discharges with the ILW, but the data points are quite scattered and the ILW discharges have, in general, a lower temperature than the CW discharges, which makes the comparison difficult. Therefore, it is too early to definitely tell anything about a possible improvement of the fuel dilution levels after the installation of the ILW.
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Edwards, Matthew C. "Design of a Continuous-Wave Synthetic Aperture Radar System with Analog Dechirp". Diss., CLICK HERE for online access, 2009. http://contentdm.lib.byu.edu/ETD/image/etd2817.pdf.
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Paepolshiri, Nattaphum. "Extending the unambiguous range of CW polyphase radar systems using number theoretic transforms". Thesis, Monterey, California. Naval Postgraduate School, 2011. http://hdl.handle.net/10945/5517.
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Approved for public release; distribution is unlimited.Polyphase continuous waveform (CW) radar systems often use the popular Frank code and P4 code due to their linear time-frequency characteristics as well as their low periodic ambiguity sidelobes. The phase relationship of the Frank code corresponds to a sawtooth folding waveform. The phase relationship of the P4 code is symmetrical with a parabolic distribution. The radar system's unambiguous target detection range is limited by the number of subcodes within the code period (code length). Increasing the code length to extend the unambiguous range results in a larger range-Doppler correlation matrix processor in the receiver, a longer compression time and an increase in the receiver's bulk memory requirements. In addition, the entire code period may not be returned from the target due to a limited time-on-target resulting in significant correlation loss. To significantly extend the unambiguous range beyond a single code period, this thesis explores the relationship between the polyphase codes (Frank and P4) and the number theoretic transforms (NTT) where the residues exhibit the same distribution as the polyphase values. The unambiguous range is extended from the number of subcodes within a single code period to the dynamic range of the transform without requiring a large increase in correlation processing. The dynamic range of a NTT is defined as the greatest length of combined phase sequences that contain no ambiguities or repeated paired terms. By transmitting N 2 coprime code periods, the unambiguous range can be extended by considering the paired values from each sequence. A new Frank phase code formulation is derived as a function of the residue number system (RNS) where each residue corresponds to a phase value within the code period (modulus) sequence. Based on the symmetrical distribution of the P4 code, a new phase code expression is derived using both the symmetrical number system (SNS) and the robust symmetrical number system (RSNS). Here each phase value within the code period corresponds to a symmetrical residue. MATLAB simulations are used to verify the new expressions for the RNS, SNS and RSNS phase codes. Implementation considerations of the new approach are also addressed.
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Malan, Frederich T. "Reduction of the antenna coupling in a bi-static, FM-CW radar system". Thesis, Stellenbosch : Stellenbosch University, 2011. http://hdl.handle.net/10019.1/18029.
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Thesis (MScEng)--Stellenbosch University, 2011.ENGLISH ABSTRACT: A well-known problem with FM-CW radar systems is the leakage of transmitter power into the receiver which leads to the making of close-in targets, and can severely limit the system dynamic range performance. This thesis considers two solutions to this radar system problem for a low frequency radar operating in the VHF band. The first method to suppress coupling is using separate transmit and receive antennas designed in such a way as to reduce coupling between them. The second is to design a negative feedback loop as part of the radar receiver where the feedback loop adaptively reduces the amount of transmitter leakage through to the receiver. This project details the realisation of these two solutions. A number of antenna designs are modelled in software and simulated to determine their characteristics of which the transmit-to-receive coupling is the key parameter. As no low coupling configuration could be found a simple configuration is chosen and practical measurements are taken. These antennas are then used in the radar system that is to be built. An FM-CW radar system is designed and simulated using software with a negative feedback loop being designed and implemented into the radar simulation. A practical radar system is then made inclusive of the feedback loop. Measurements are then taken to determine the efficacy of the feedback loop.
AFRIKAANSE OPSOMMING: ʼn Bekende probleem met FM-CW radar stelsels is die lekkasie van versender krag tot in die ontvanger wat lei tot die maak van nabye teikens en kan die stelsel se dinamiese sendbereik steng beperk. Hierdie tesis oorweeg twee oplossings tot hierdie probleem vir ʼn lae frekwensie radar wat in die VHF band werk. Die eerste metode wat na gekyk word om die koppeling te onderdruk is om die twee antennas van die radar stelsel so te ontwerp sodat die hoeveelheid koppeling tussen hulle verminder is. Die tweede is om ʼn negatiewe terugvoerlus as deel van die ontvanger te ontwerp. Hierdie terugvoerlus sal die versender lekkasie sein aanpassend in die ontvanger verminder. In hierdie projek word die realisering van bogenoemde oplossings uiteengeset. ʼn Paar verskillende antenna ontwerpe word gemodelleer in sagteware en word gesimuleer om hul karakteristieke te bepaal. Die belangrikste van hierdie faktore is die versender na ontvanger koppeling. Sienend dat geen ontwerp met ʼn lae genoeg koppeling gevind kon word nie, is ʼn eenvoudige ontwerp gekies en praktiese metings daarvan geneem. Hierdie antennas word dan gebruik in die radar stelsel wat gebou sal word. ʼn FM-CW radar stelsel word ontwerp en gesimuleer in sagteware. Die negatiewe terugvoerlus word ook ontwerp en geïmplementeer in die radar simulasie. ʼn Praktiese radar stelsel word dan gemaak insluitend die terugvoerlus. Metings word dan geneem om die effektiwiteit daarvan te bepaal.
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Bertoni, Anna. "Molecular mechanisms controlling the expression of the HLA-Cw*06 psoriasis susceptibility allele". Thesis, King's College London (University of London), 2013. https://kclpure.kcl.ac.uk/portal/en/theses/molecular-mechanisms-controlling-the-expression-of-the-hlacw06-psoriasis-susceptibility-allele(9ab9c311-68f1-4519-913f-45872a59d164).html.
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Psoriasis is an inflammatory skin disorder that is inherited as a common and complex trait. Linkage studies have repeatedly identified a primary disease susceptibility locus (PSORS1) spanning 250 kb within the Major Histocompatibility Complex. Deep sequencing experiments and genome-wide association scans have highlighted HLA-C as the most likely PSORS1 gene and unambiguously demonstrated that the HLA-Cw*0602 allele confers increased disease risk in a wide range of populations. In this context, the aim of this project was to investigate the impact of PSORS1 genetic variation on HLA-C transcription, with a particular focus on HLA-Cw*0602 expression. In the first part of the study, genetic variants mapping to the regulatory elements of different HLA-C alleles were characterized, by measuring the basal and cytokineinduced reporter activity driven by the HLA-Cw*0602, -Cw*0702 and -Cw*0304 promoters. These experiments identified two regulatory polymorphisms that virtually abolished the response to TNF-α (rs2524094) and IFN-γ (rs10657191) in HLA-Cw*0602 constructs. The existence of a differential cytokine response was also confirmed by the real-time PCR analysis of primary keratinocytes treated with TNF-α and IFN-γ. Since little is known about the role of epigenetic factors in the regulation of HLA-C expression, the presence of HLA-Cw*0602 specific modification patterns was examined in the second part of the project. The methylation status of the five PSORS1 CpG islands (CGIs) was initially investigated. This targeted approach revealed lack of methylation at four CGIs, two of which mapped within the HLA-C gene region. Partial methylation was detected at a fifth CGI, lying upstream of POU5F1. To complement these data, a methylation profile of the entire PSORS1 locus was generated in two HLA Cw*0602,-Cw*0702 heterozygous individuals. This showed that the majority of methylated cytosines mapped between the POU5F1 and C6orf15 transcripts, and upstream of HLA-C. Neither the targeted CGI analysis nor the systematic profiling of the entire PSORS1 region revealed any substantial differences in the methylation status of haplotypes bearing different HLA-C alleles. Taken together, the results of this study indicate that HLA-C expression is tightly controlled by promoter variants and immunological stimuli. Further studies will be required to fully explore the impact of genetic variation on DNA methylation and to determine whether PSORS1 epigenetic modifications play a role in psoriasis susceptibility.