Dissertations / Theses on the topic 'Terrestrial and marine systems'
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Bergström, Ulf. "Spatial heterogeneity and biotic interactions : scaling from experiments to natural systems." Doctoral thesis, Umeå University, Ecology and Environmental Science, 2004. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-249.
Full textMuch of current ecological theory stems from experimental studies. These studies have often been conducted in closed systems, at spatial scales that are much smaller than the systems of interest. It is known that the outcome of these experiments may be seriously affected by artefacts associated with the caging procedures, as well as by the actual difference in spatial scale between experimental and target system. Yet, quantitative methods for estimating and removing artefacts of enclosure and for extrapolating experimental results to the scales of natural systems are largely lacking.
The aim of this thesis was to confront some of the problems encountered when scaling from experiments to nature in studies on predator-prey systems, with focus on effects of changes in spatial heterogeneity. Specifically, I examined mechanisms that may cause consumption rate estimates to depend on the size of the experimental arena. I also studied methods for scaling up these process rate estimates to natural predator-prey systems. The studies were performed on invertebrate predator-prey systems found in the northern Baltic Sea. Initially, a descriptive study of small-scale distribution patterns was performed, in order to get background information on how the behaviour of the organisms was manifested in the spatial structure of the community. Experimental studies of two predator-prey systems exposed an artefact that may be widespread in experiments aiming at quantifying biotic interactions. It is caused by predator and prey aggregating along the walls of the experimental containers. This behaviour affects the encounter rate between predator and prey, thereby causing consumption rates to be scale-dependent. Opposing the common belief that larger arenas always produce less biased results, this scale effect may instead be reduced by decreasing arena size. An alternative method for estimating the magnitude of, and subsequently removing, the artefact caused by aggregation along the arena wall was presented.
Once unbiased estimates of process functions have been derived, the next step is to scale up the functions to natural systems. This extrapolation entails a considerable increase in spatial heterogeneity, which may have important implications for the dynamics of the system. Moment approximation provides a method of taking the heterogeneity of natural populations into account in the extrapolation process. In the last study of the thesis, the concepts of moment approximation and how to estimate relevant heterogeneity were explained, and it was shown how the method may be used for adding space as a component to a dynamic predator-prey model. It was concluded that moment approximation provides a simple and useful technique for dealing with effects of spatial variation, and that a major benefit of the method is that it provides a way of visualising how heterogeneity affects ecological processes.
Karlberg, Louise. "Irrigation with saline water using low-cost drip-irrigation systems in sub-Saharan Africa." Doctoral thesis, Stockholm, 2005. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-209.
Full textLövgren, Johan. "Food web dynamics in open and closed systems." Doctoral thesis, Umeå University, Ecology and Environmental Science, 2004. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-269.
Full textThis thesis is a summary of enclosure and microcosm experiments that aimed to study the impact of allochtonous subsidies on food web dynamics in a heterogeneous food web. In the enclosure studies, a three trophic level littoral food web was used. The food web consisted of two growth forms of primary producers: phytoplankton and periphyton and their associated herbivores: scraping and filtering herbivores. The predator used, YOY perch, affects both pathways in the food web. Manipulation of the openness for the different trophic levels showed that the inflow of phytoplankton and cross-habitat foraging by the herbivore level reinforced the compensatory response between the two growth forms of primary producers
In the microcosm experiment, the response of an herbivore food web and a microbial community to inflow of resources and food web configuration was studied, using a model food web. The model food web consisted of two forms of primary producers, i.e. phytoplankton and periphyton, and two herbivores, i.e. Daphnia pulex feeding on phytoplankton, and Chydorus sphaericus feeding on both periphyton and phytoplankton. Three different food web configurations, all having the phytoplankton and periphyton, but either one of the herbivores, or both, were set up. The flow regimes consisted of an open treatment receiving a constant supply of phytoplankton, and a closed treatment with an initial resource pool. The effect of the inflow of phytoplankton was affected by the food web configuration. In the presence of D. pulex, the inflow of phytoplankton was made accessible to periphyton, and indirectly to C. sphaericus, which increased to such high densities that D. pulex was negatively affected. The inflow of phytoplankton had an indirect negative effect on the microbial community, since the biomass of herbivores increased, which imposed a higher grazing pressure on all parts of the microbial community.
Huitric, Miriam. "Masking environmental feedback : Misfits between institutions and ecosystems in Belize and Thailand." Doctoral thesis, Stockholm : Institutionen för systemekologi, Univ, 2004. http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-176.
Full textBrown, Tanya. "Phenomenological and Molecular Basis of the Cnidarian Immune System." FIU Digital Commons, 2017. http://digitalcommons.fiu.edu/etd/3468.
Full textTengö, Maria. "Management Practices for Dealing with Uncertainty and Change : Social-Ecological Systems in Tanzania and Madagascar." Doctoral thesis, Stockholms universitet, Institutionen för systemekologi, 2004. http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-309.
Full textDias, Daniel Anthony, and danieldias@iprimus com au. "Natural Product Studies of Terrestrial and Marine Organisms." RMIT University. Applied Sciences, 2009. http://adt.lib.rmit.edu.au/adt/public/adt-VIT20091019.161302.
Full textGallimore, A. R. "The biogenesis of terrestrial and marine polycyclic ethers." Thesis, University of Cambridge, 2007. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.599282.
Full textStevenson, Emily Isabel. "Stable strontium isotope fractionation in marine and terrestrial environments." Thesis, University of Oxford, 2012. http://ora.ox.ac.uk/objects/uuid:a2d97fc7-3e9d-484a-8026-11c118fcc3fd.
Full textPage, Catherine. "Investigation of the cytogenetics of marine and terrestrial gastropods." Thesis, London Metropolitan University, 1985. http://repository.londonmet.ac.uk/3431/.
Full textBoot, Christopher Stephen. "Reconstruction of climate and vegetation change from marine sediments dominated by terrestrial and marine inputs." Thesis, University of Bristol, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.420907.
Full textRussell, Duncan William. "The measurement of dimethylsulphide precursors in marine and terrestrial flora." Thesis, University of Southampton, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.242458.
Full textCollett, Lynne Alison. "Structural and stereochemical investigations of terrestrial and marine pyrone metabolites." Thesis, Rhodes University, 1997. http://hdl.handle.net/10962/d1005013.
Full textPulley, D. R. "Synchronisation for terrestrial mobile radio systems." Thesis, University of Bath, 1993. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.760633.
Full textCatenazzi, Alessandro. "The importance of marine subsidies for terrestrial consumers in coastal Peru." FIU Digital Commons, 2006. http://digitalcommons.fiu.edu/etd/2086.
Full textShahri, Javad Yazdani Kohneh. "High frequency digital power line transmission for terrestrial and marine networks." Thesis, Lancaster University, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.288950.
Full textHey, Anna Rose. "Palaeoclimate reconstructions from the Antarctic Peninsula : linking marine and terrestrial records." Thesis, Cardiff University, 2009. http://orca.cf.ac.uk/54846/.
Full textWright, Joanna L. "Fossil terrestrial trackways : function, taphonomy and palaeoecological significance." Thesis, University of Bristol, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.389379.
Full textPricope, Bogdan [Verfasser]. "Positioning using terrestrial wireless systems / Bogdan Pricope." Bremen : IRC-Library, Information Resource Center der Jacobs University Bremen, 2013. http://d-nb.info/1037014111/34.
Full textIsdell, Robert Earl. "Anthropogenic Modifications of Connectivity at the Aquatic-Terrestrial Ecotone in the Chesapeake Bay." W&M ScholarWorks, 2014. https://scholarworks.wm.edu/etd/1539626955.
Full textFolmer, Florence. "Investigations of marine and terrestrial natural products with NF-kappaB inhibitory properties." Thesis, University of Aberdeen, 2007. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.446582.
Full textSime, Neil Graham. "Calcium isotope variations in marine and terrestrial carbonates over the past 20 Ma." Thesis, University of Cambridge, 2006. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.614206.
Full textVelasquez, Eleanor. "Unique island habitats: A comparison of community assembly in marine and terrestrial contexts." Thesis, Queensland University of Technology, 2019. https://eprints.qut.edu.au/124649/2/Eleanor%20Velasquez%20Thesis.pdf.
Full textRobert, Jörg [Verfasser]. "Terrestrial TV Broadcast Using Multi-Antenna Systems / Jörg Robert." Aachen : Shaker, 2013. http://d-nb.info/1049381769/34.
Full textHoldaway, Robert James. "A systems perspective on the development of terrestrial ecosystems." Thesis, University of Cambridge, 2010. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.608477.
Full textEatchel, Andrew L. "Imaging exo-solar planetary systems with Terrestrial Planet Finder." Diss., The University of Arizona, 2004. http://hdl.handle.net/10150/280604.
Full textSumner-Rooney, Lauren Héloïse. "Sensory systems in marine invertebrates." Thesis, Queen's University Belfast, 2016. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.709845.
Full textSwasono, Respati Tri. "Bioactive secondary metabolites from Australian invertebrates, Indonesian marine sponges, and an Indonesian terrestrial plant /." [St. Lucia, Qld.], 2006. http://www.library.uq.edu.au/pdfserve.php?image=thesisabs/absthe19275.pdf.
Full textCentko, Ryan Matthew. "Isolation, synthesis, and biological target identification of natural products from terrestrial and marine environments." Thesis, University of British Columbia, 2014. http://hdl.handle.net/2429/50064.
Full textScience, Faculty of
Chemistry, Department of
Graduate
Miladinovic, Natalija D. "Biological interactions during ion exchange removal of ammonia from terrestrial and marine waste water." Thesis, University of Canterbury. Chemical and Process Engineering, 2005. http://hdl.handle.net/10092/7514.
Full textD'Andrilli, Juliana. "Molecular characterization of marine and terrestrial dissolved organic matter using ultrahigh resolution mass spectrometry." Tallahassee, Fla. : Florida State University, 2009. http://etd.lib.fsu.edu/theses/available/etd-07102009-111543/.
Full textAdvisor: William T. Cooper III, Florida State University, College of Arts and Sciences, Dept. of Chemistry and Biochemistry. Title and description from dissertation home page (viewed Nov. 8, 2009). Document formatted into pages; contains xviii, 119 pages. Includes bibliographical references.
Armstrong, Christen Taylor. "Nitrogen Isotope Fractionation and Toxin Production during The Uptake of Micromolar Concentrations of Nitrate, Ammonium, and Urea By A Marine Dinoflagellate." W&M ScholarWorks, 2017. https://scholarworks.wm.edu/etd/1499449867.
Full textVargas, Paredero David Eduardo. "Transmit and Receive Signal Processing for MIMO Terrestrial Broadcast Systems." Doctoral thesis, Universitat Politècnica de València, 2016. http://hdl.handle.net/10251/66081.
Full text[ES] La tecnología de múltiples entradas y múltiples salidas (MIMO) en redes de Televisión Digital Terrestre (TDT) tiene el potencial de incrementar la eficiencia espectral y mejorar la cobertura de red para afrontar las demandas de uso del escaso espectro electromagnético (e.g., designación del dividendo digital y la demanda de espectro por parte de las redes de comunicaciones móviles), la aparición de nuevos contenidos de alta tasa de datos (e.g., ultra-high definition TV - UHDTV) y la ubicuidad del contenido (e.g., fijo, portable y móvil). Es ampliamente reconocido que MIMO puede proporcionar múltiples beneficios como: potencia recibida adicional gracias a las ganancias de array, mayor robustez contra desvanecimientos de la señal gracias a la diversidad espacial y mayores tasas de transmisión gracias a la ganancia por multiplexado del canal MIMO. Estos beneficios se pueden conseguir sin incrementar la potencia transmitida ni el ancho de banda, pero normalmente se obtienen a expensas de una mayor complejidad del sistema tanto en el transmisor como en el receptor. Las ganancias de rendimiento finales debido al uso de MIMO dependen directamente de las características físicas del entorno de propagación como: la correlación entre los canales espaciales, la orientación de las antenas y/o los desbalances de potencia sufridos en las antenas transmisoras. Adicionalmente, debido a restricciones en la complejidad y aritmética de precisión finita en los receptores, es fundamental para el rendimiento global del sistema un diseño cuidadoso de algoritmos específicos de procesado de señal. Esta tesis doctoral se centra en el procesado de señal, tanto en el transmisor como en el receptor, para sistemas TDT que implementan MIMO-BICM (Bit-Interleaved Coded Modulation) sin canal de retorno hacia el transmisor desde los receptores. En el transmisor esta tesis presenta investigaciones en precoding MIMO en sistemas TDT para superar las degradaciones del sistema debidas a diferentes condiciones del canal. En el receptor se presta especial atención al diseño y evaluación de receptores prácticos MIMO-BICM basados en información cuantificada y a su impacto tanto en la memoria del chip como en el rendimiento del sistema. Estas investigaciones se llevan a cabo en el contexto de estandarización de DVB-NGH (Digital Video Broadcasting - Next Generation Handheld), la evolución portátil de DVB-T2 (Second Generation Terrestrial), y ATSC 3.0 (Advanced Television Systems Commitee - Third Generation) que incorporan MIMO-BICM como clave tecnológica para superar el límite de Shannon para comunicaciones con una única antena. No obstante, esta tesis doctoral emplea un método genérico tanto para el diseño, análisis y evaluación, por lo que los resultados e ideas pueden ser aplicados a otros sistemas de comunicación inalámbricos que empleen MIMO-BICM.
[CAT] La tecnologia de múltiples entrades i múltiples eixides (MIMO) en xarxes de Televisió Digital Terrestre (TDT) té el potencial d'incrementar l'eficiència espectral i millorar la cobertura de xarxa per a afrontar les demandes d'ús de l'escàs espectre electromagnètic (e.g., designació del dividend digital i la demanda d'espectre per part de les xarxes de comunicacions mòbils), l'aparició de nous continguts d'alta taxa de dades (e.g., ultra-high deffinition TV - UHDTV) i la ubiqüitat del contingut (e.g., fix, portàtil i mòbil). És àmpliament reconegut que MIMO pot proporcionar múltiples beneficis com: potència rebuda addicional gràcies als guanys de array, major robustesa contra esvaïments del senyal gràcies a la diversitat espacial i majors taxes de transmissió gràcies al guany per multiplexat del canal MIMO. Aquests beneficis es poden aconseguir sense incrementar la potència transmesa ni l'ample de banda, però normalment s'obtenen a costa d'una major complexitat del sistema tant en el transmissor com en el receptor. Els guanys de rendiment finals a causa de l'ús de MIMO depenen directament de les característiques físiques de l'entorn de propagació com: la correlació entre els canals espacials, l'orientació de les antenes, i/o els desequilibris de potència patits en les antenes transmissores. Addicionalment, a causa de restriccions en la complexitat i aritmètica de precisió finita en els receptors, és fonamental per al rendiment global del sistema un disseny acurat d'algorismes específics de processament de senyal. Aquesta tesi doctoral se centra en el processament de senyal tant en el transmissor com en el receptor per a sistemes TDT que implementen MIMO-BICM (Bit-Interleaved Coded Modulation) sense canal de tornada cap al transmissor des dels receptors. En el transmissor aquesta tesi presenta recerques en precoding MIMO en sistemes TDT per a superar les degradacions del sistema degudes a diferents condicions del canal. En el receptor es presta especial atenció al disseny i avaluació de receptors pràctics MIMO-BICM basats en informació quantificada i al seu impacte tant en la memòria del xip com en el rendiment del sistema. Aquestes recerques es duen a terme en el context d'estandardització de DVB-NGH (Digital Video Broadcasting - Next Generation Handheld), l'evolució portàtil de DVB-T2 (Second Generation Terrestrial), i ATSC 3.0 (Advanced Television Systems Commitee - Third Generation) que incorporen MIMO-BICM com a clau tecnològica per a superar el límit de Shannon per a comunicacions amb una única antena. No obstant açò, aquesta tesi doctoral empra un mètode genèric tant per al disseny, anàlisi i avaluació, per la qual cosa els resultats i idees poden ser aplicats a altres sistemes de comunicació sense fils que empren MIMO-BICM.
Vargas Paredero, DE. (2016). Transmit and Receive Signal Processing for MIMO Terrestrial Broadcast Systems [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/66081
TESIS
Premiado
Fuentes, Muela Manuel. "Non-Uniform Constellations for Next-Generation Digital Terrestrial Broadcast Systems." Doctoral thesis, Universitat Politècnica de València, 2017. http://hdl.handle.net/10251/84743.
Full textHoy en día, el mercado de la televisión digital terrestre (TDT) está caracterizado por la alta capacidad requerida para transmitir servicios de televisión de alta definición y el espectro disponible. Es necesario por tanto un uso eficiente del espectro radioeléctrico, el cual requiere nuevas tecnologías para garantizar mayores capacidades. Las constelaciones no-uniformes (NUC) emergen como una de las técnicas más innovadoras para abordar tales requerimientos. Las NUC reducen el espacio existente entre las constelaciones uniformes QAM y el límite teórico de Shannon. Con estas constelaciones, los símbolos se optimizan en ambas componentes fase (I) y cuadratura (Q) mediante técnicas geométricas de modelado de la señal, considerando un nivel señal a ruido (SNR) concreto y un modelo de canal específico. Hay dos tipos de NUC, unidimensionales y bidimensionales (1D-NUC y 2D-NUC, respectivamente). Las 1D-NUC mantienen la forma cuadrada de las QAM, pero permiten cambiar la distribución entre los símbolos en una componente concreta, teniendo una distancia no uniforme entre ellos. Estas constelaciones proporcionan un mejor rendimiento SNR que QAM, sin ningún incremento en la complejidad en el demapper. Las 2D-NUC también permiten cambiar la forma cuadrada de la constelación, permitiendo optimizar los símbolos en ambas dimensiones y por tanto obteniendo mayores ganancias en capacidad y menores requerimientos en SNR. Sin embargo, el uso de 2D-NUCs implica una mayor complejidad en el receptor. En esta tesis se analizan las NUC desde el punto de vista tanto de transmisión como de recepción, utilizando bien configuraciones con una antena (SISO) o con múltiples antenas (MIMO). En transmisiones SISO, se han optimizado 1D-NUCs para un rango amplio de distintas SNR y varios órdenes de constelación. También se ha investigado la optimización de 2D-NUCs rotadas. Aunque la complejidad no aumenta, la ganancia SNR de estas constelaciones no es significativa. La mayor ganancia por rotación se obtiene para bajos órdenes de constelación y altas SNR. Sin embargo, utilizando técnicas multi-RF, la ganancia aumenta drásticamente puesto que las componentes I y Q se transmiten en distintos canales RF. En esta tesis, se han estudiado varias ganancias multi-RF representativas de las NUC, con o sin rotación. En el receptor, se han identificado dos cuellos de botella diferentes en la implementación. Primero, se ha analizado la complejidad en el receptor para todas las constelaciones consideradas y, posteriormente, se proponen dos algoritmos para reducir la complejidad con 2D-NUCs. Además, los dos pueden combinarse en un único demapper. También se ha explorado la cuantización de estas constelaciones, ya que tanto los valores LLR como las componentes I/Q se ven modificados, comparando con constelaciones QAM tradicionales. Además, se ha propuesto un algoritmo que se basa en la optimización para diferentes niveles de cuantización, para una NUC concreta. Igualmente, se ha investigado en detalle el uso de NUCs en MIMO. Se ha incluido la optimización en una sola o en dos antenas, el uso de un desbalance de potencia, factores de discriminación entre antenas receptoras (XPD), o el uso de distintos demappers. Asumiendo distintos valores, se han obtenido nuevas constelaciones multi-antena (MA-NUC) gracias a un nuevo proceso de re-optimización específico para MIMO. En el receptor, se ha extendido el análisis de complejidad en el demapper, la cual se incrementa enormemente con el uso de 2D-NUCs y sistemas MIMO. Como alternativa, se propone una solución basada en el algoritmo Soft-Fixed Sphere Decoding (SFSD). El principal problema es que estos demappers no funcionan con 2D-NUCs, puesto que necesitan de un paso adicional en el que las componentes I y Q necesitan separarse. El método propuesto cuantifica el símbolo más cercano utilizando las regiones de Voronoi, permitiendo el uso de este tipo de receptor.
Actualment, el mercat de la televisió digital terrestre (TDT) està caracteritzat per l'alta capacitat requerida per a transmetre servicis de televisió d'alta definició i l'espectre disponible. És necessari per tant un ús eficient de l'espectre radioelèctric, el qual requereix noves tecnologies per a garantir majors capacitats i millors servicis. Les constel·lacions no-uniformes (NUC) emergeixen com una de les tècniques més innovadores en els sistemes de televisió de següent generació per a abordar tals requeriments. Les NUC redueixen l'espai existent entre les constel·lacions uniformes QAM i el límit teòric de Shannon. Amb estes constel·lacions, els símbols s'optimitzen en ambdós components fase (I) i quadratura (Q) per mitjà de tècniques geomètriques de modelatge del senyal, considerant un nivell senyal a soroll (SNR) concret i un model de canal específic. Hi ha dos tipus de NUC, unidimensionals i bidimensionals (1D-NUC i 2D-NUC, respectivament). 1D-NUCs mantenen la forma quadrada de les QAM, però permet canviar la distribució entre els símbols en una component concreta, tenint una distància no uniforme entre ells. Estes constel·lacions proporcionen un millor rendiment SNR que QAM, sense cap increment en la complexitat al demapper. 2D-NUC també canvien la forma quadrada de la constel·lació, permetent optimitzar els símbols en ambdós dimensions i per tant obtenint majors guanys en capacitat i menors requeriments en SNR. No obstant això, l'ús de 2D-NUCs implica una major complexitat en el receptor, ja que es necessita un demapper 2D, on les components I i Q no poden ser separades. En esta tesi s'analitzen les NUC des del punt de vista tant de transmissió com de recepció, utilitzant bé configuracions amb una antena (SISO) o amb múltiples antenes (MIMO). En transmissions SISO, s'han optimitzat 1D-NUCs, per a un rang ampli de distintes SNR i diferents ordes de constel·lació. També s'ha investigat l'optimització de 2D-NUCs rotades. Encara que la complexitat no augmenta, el guany SNR d'estes constel·lacions no és significativa. El major guany per rotació s'obté per a baixos ordes de constel·lació i altes SNR. No obstant això, utilitzant tècniques multi-RF, el guany augmenta dràsticament ja que les components I i Q es transmeten en distints canals RF. En esta tesi, s'ha estudiat el guany multi-RF de les NUC, amb o sense rotació. En el receptor, s'han identificat dos colls de botella diferents en la implementació. Primer, s'ha analitzat la complexitat en el receptor per a totes les constel·lacions considerades i, posteriorment, es proposen dos algoritmes per a reduir la complexitat amb 2D-NUCs. Ambdós algoritmes redueixen dràsticament el nombre de distàncies. A més, els dos poden combinar-se en un únic demapper. També s'ha explorat la quantització d'estes constel·lacions, ja que tant els valors LLR com les components I/Q es veuen modificats, comparant amb constel·lacions QAM tradicionals. A més, s'ha proposat un algoritme que es basa en l'optimització per a diferents nivells de quantització, per a una NUC concreta. Igualment, s'ha investigat en detall l'ús de NUCs en MIMO. S'ha inclòs l'optimització en una sola o en dos antenes, l'ús d'un desbalanç de potència, factors de discriminació entre antenes receptores (XPD), o l'ús de distints demappers. Assumint distints valors, s'han obtingut noves constel·lacions multi-antena (MA-NUC) gràcies a un nou procés de re-optimització específic per a MIMO. En el receptor, s'ha modificat l'anàlisi de complexitat al demapper, la qual s'incrementa enormement amb l'ús de 2D-NUCs i sistemes MIMO. Com a alternativa, es proposa una solució basada en l'algoritme Soft-Fixed Sphere Decoding (SFSD) . El principal problema és que estos demappers no funcionen amb 2D-NUCs, ja que necessiten d'un pas addicional en què les components I i Q necessiten separar-se. El mètode proposat quantifica el símbol més pròxim utilitzan
Fuentes Muela, M. (2017). Non-Uniform Constellations for Next-Generation Digital Terrestrial Broadcast Systems [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/84743
TESIS
Sri, Rangan Nithyakalyani [Verfasser]. "Investigation on the primary and secondary metabolism of marine and terrestrial endosymbionts / Nithyakalyani Sri Rangan." Greifswald : Universitätsbibliothek Greifswald, 2017. http://d-nb.info/1134994176/34.
Full textSt, John Emily Joyce. "Symbiosis in Archaea: Functional and Phylogenetic Diversity of Marine and Terrestrial Nanoarchaeota and their Hosts." PDXScholar, 2019. https://pdxscholar.library.pdx.edu/open_access_etds/4939.
Full textSandbakken, Egil Christoffer. "Marine Machinery Systems - Tools and Architecture." Thesis, Norges teknisk-naturvitenskapelige universitet, Institutt for marin teknikk, 2010. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-11614.
Full textCunliffe, Nicholas David. "Evolutionary Design of Marine Riser Systems." Thesis, University of Manchester, 2004. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.518864.
Full textColley, B. A. "Computer simulation of marine traffic systems." Thesis, University of Plymouth, 1985. http://hdl.handle.net/10026.1/2223.
Full textFullarton, J. Gregor. "Lipid biomarkers in marine symbiotic systems." Thesis, University of Stirling, 1993. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.384931.
Full textHemingway, Jordon Dennis. "Understanding terrestrial organic carbon export : a time-series approach." Thesis, Massachusetts Institute of Technology, 2017. http://hdl.handle.net/1721.1/109054.
Full textCataloged from PDF version of thesis.
Includes bibliographical references (pages 169-190).
Terrestrial organic carbon (OC) erosion, remineralization, transport through river networks, and burial in marine sediments is a major pathway of the global carbon cycle. However, our ability to constrain these processes and fluxes is largely limited by (i) analytical capability and (ii) temporal sampling resolution. To address issue (i), here I discuss methodological advancements and data analysis techniques for the Ramped PyrOx serial oxidation isotope method developed at WHOI. Ramped-temperature pyrolysis/oxidation coupled with the stable carbon (¹²C, ¹³C) and radiocarbon (¹⁴C) analysis of evolved CO₂ is a promising tool for understanding and separating complex OC mixtures. To quantitatively investigate distributions of OC source, reservoir age, and chemical structure contained within a single sample, I developed a kinetic model linking RPO-derived activation energy, ¹³C composition, and radiocarbon content. This tool provides a novel method to fundamentally address the unknown relationship between OC remineralization rates and chemical structure in various environmental settings. To address issue (ii), I additionally present results from time-series sample sets collected on two end-member systems: the Congo River (Central Africa) and the LiWu River (Taiwan). For the Congo River, bulk and plant-wax-lipid ¹³C compositions indicate that a majority of particulate OC is consistently derived from downstream, C₃-dominated rainforest ecosystems. Furthermore, bulk radiocarbon content and microbial lipid molecular distributions are strongly correlated with discharge, suggesting that pre-aged, swamp-forest-derived soils are preferentially exported when northern hemisphere discharge is highest. Combined, these results provide insight into the relationship between hydrological processes and fluvial carbon export. Lastly, I examined the processes controlling carbon source and flux in a set of soils and time-series fluvial sediments from the LiWu River catchment located in Taiwan. A comparison between bedrock and soil OC content reveals that soils can contain significantly less carbon than the underlying bedrock, suggesting that this material is remineralized to CO₂ prior to soil formation. Both the presence of bacterial lipids and a shift toward lower activation energy of ¹⁴C-free OC contained in soil saprolite layers indicate that this process is microbially mediated and that microbial respiration of rock-derived OC likely represents a larger geochemical flux than previously thought. The results presented in this thesis therefore provide novel insight into the role of rivers in the global carbon cycle as well as their response to environmental perturbations.
by Jordon Dennis Hemingway
Ph. D.
Benitez-Nelson, Bryan C. "Marine sedimentary organic matter: delineation of marine and terrestrial sources through radiocarbon dating; and the role of organic sulfur in early petroleum generation." Thesis, Massachusetts Institute of Technology, 1996. http://hdl.handle.net/1721.1/58536.
Full text"May 1996."
Includes bibliographical references (leaves 66-68).
This thesis details two years of research conducted with the guidance and support of three advisors: Dr. J. K. Whelan, Dr. J. S. Seewald and Dr. T. I. Eglinton. Each of the three chapters represents a different, self-contained research project. All of the projects are related to the organic geochemistry of marine sediments, however, this is a fairly encompassing area of study. Chapters 1 and 2 stem from the same experimental study -- the use of hydrous-pyrolysis to investigate mechanisms leading to the production of petroleum-related products during kerogen maturation. Chapter 3, on the other hand, utilizes a recently developed technique of isolating and AMS-14C dating individual compounds from complex sedimentary organic mixtures. The samples used in each investigation came from all over the world. The first two chapters utilize ancient marine sediment samples obtained from an outcrop in California (Chpts. 1 and 2) and from a well in Alabama (Chpt. 2). In contrast, recent marine sediment samples were obtained from the Arabian and Black Seas for the third chapter. Several preparative and analytical methods are common to all three studies. Nevertheless, each employ techniques totally unique from one another and from previous investigations. In Chapter 1, for example, X-ray absorption spectroscopy (XANES) is used to determine the speciation of organic sulfur present in kerogen, bitumen, and bulk sediment samples. While Chapter 3 represents the first study in which the "4C ages of individual, known hydrocarbon biomarkers are determined after isolation by Preparative Capillary Gas Chromatography (PCGC). The insights gained by these investigations are discussed in detail in the following chapters. The common thread between the three chapters is that the source of organic matter, the rate at which it is delivered to marine sediments and the depositional environment, all set the stage for kerogen formation and eventual petroleum generation.
by Bryan C. Benitez-Nelson.
M.S.
Blachman, Sara Aimee. "Modeling Phytoplankton Community Response to Nutrient Loading and Climate Change in A Shallow Temperate Estuary." W&M ScholarWorks, 2016. https://scholarworks.wm.edu/etd/1499449661.
Full textStrand, Sarah Elise. "Stable Isotope Biogeochemistry of South Florida Coastal Marine Ecosystems." FIU Digital Commons, 2014. http://digitalcommons.fiu.edu/etd/1737.
Full textDawkins, Mark Tristan. "UP-integration in radio-frequency tuners for digital terrestrial television." Thesis, Imperial College London, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.269767.
Full textFairbanks, Douglas O. "Role of Terrestrial Organic Matter in Food Webs of the Rocky Intertidal Zone." BYU ScholarsArchive, 2017. https://scholarsarchive.byu.edu/etd/6520.
Full textRadan, Damir. "Integrated Control of Marine Electrical Power Systems." Doctoral thesis, Norwegian University of Science and Technology, Faculty of Engineering Science and Technology, 2008. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-1984.
Full textThis doctoral thesis presents new ideas and research results on control of marine electric power system.
The main motivation for this work is the development of a control system, power management system (PMS) capable to improve the system robustness to blackout, handle major power system faults, minimize the operational cost and keep the power system machinery components under minimal stress in all operational conditions.
Today, the electric marine power system tends to have more system functionality implemented in integrated automation systems. The present state of the art type of tools and methods for analyzing marine power systems do only to a limited extent utilize the increased knowledge available within each of the mechanical and electrical engineering disciplines.
As the propulsion system is typically consisted of the largest consumers on the vessel, important interactions exists between the PMS and vessel propulsion system. These are interacted through the dynamic positioning (DP) controller, thrust allocation algorithm, local thruster controllers, generators' local frequency and voltage controllers. The PMS interacts with the propulsion system through the following main functions: available power static load control, load rate limiting control and blackout prevention control (i.e. fast load reduction). These functions serve to prevent the blackout and to ensure that the vessel will always have enough power.
The PMS interacts with other control systems in order to prevent a blackout and to minimize operational costs. The possibilities to maximize the performance of the vessel, increase the robustness to faults and decrease a component wear-out rate are mainly addressed locally for the individual control systems. The solutions are mainly implicative (for e.g. local thruster control, or DP thrust allocation), and attention has not been given on the interaction between these systems, the power system and PMS. Some of the questions that may arise regarding the system interactions, are as follows: how the PMS functionality may affect a local thruster control, how the local thruster control may affect the power system performance, how some consumers may affect the power system performance in normal operations and thus affect other consumers, how the power system operation may affect the susceptibility to faults and blackout, how various operating and weather conditions may affect the power system performance and thus propulsion performance though the PMS power limiting control, how propulsion performance may affect the overall vessel performance, which kind of faults can be avoided if the control system is re-structured, how to minimize the operational costs and to deal with the conflicting goals. This PhD thesis aims to provide answers to such questions.
The main contributions of this PhD thesis are:
− A new observer-based fast load reduction system for the blackout prevention control has been proposed. When compared to the existing fast load reduction systems, the proposed controller gives much faster blackout detection rate, high reliability in the detection and faster and more precise load reduction (within 150 miliseconds).
− New advanced energy management control strategies for reductions in the operational costs and improved fuel economy of the vessel.
− Load limiting controllers for the reduction of thruster wear-out rate. These controllers are based on the probability of torque loss, real-time torque loss and the thruster shaft
accelerations. The controllers provide means of redistributing thrust from load fluctuating thrusters to less load fluctuating ones, and may operate independently of the thrust allocation system. Another solution is also proposed where the load limiting controller based on thrust losses is an integrated part of DP thrust allocation algorithm.
− A new concept of totally integrated thrust allocation system, local thruster control and power system. These systems are integrated through PMS functionality which is contained within each thruster PLC, thereby distributed among individual controllers, and independent of the communications and dedicated controllers.
− Observer-based inertial controller and direct torque-loss controller (soft anti-spin controller) with particular attention to the control of machine wear-out rate. These controller contribute to general shaft speed control of electrical thrusters, generators and main propulsion prime movers.
The proposed controllers, estimators and concepts are demonstrated through time-domain simulations performed in MATLAB/SIMULINK. The selected data are typical for the required applications and may differ slightly for the presented cases.
Pedersen, Tom Arne. "Bond Graph Modeling of Marine Power Systems." Doctoral thesis, Norges teknisk-naturvitenskapelige universitet, Institutt for marin teknikk, 2009. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-5494.
Full textHuang, Shan. "Analysis and control of marine cable systems." Thesis, University of Strathclyde, 1992. http://oleg.lib.strath.ac.uk:80/R/?func=dbin-jump-full&object_id=21240.
Full textMeskill, Shay J. "Applications of marine radar wave observation systems." Thesis, Oregon Oregon State University, 2009. http://hdl.handle.net/10945/4299.
Full textApproved for public release, distribution unlimited
This project utilized both shore-based and shipboard commercial marine radar technology to collect wave statistics. In the first application a shore-based system was installed at Yaquina Bay in Newport, Oregon in order to collect real-time wave information. This information was collected under the auspices of the Northwest Association of Networked Ocean Observing Systems (NANOOS) and will be used in ongoing studies on wave-current interaction. In the second application, a shipboard radar system was utilized to develop processing procedures and algorithms for collecting offshore wave data. These shipboard collections were in support of the environmental baseline study of the Reedsport Wave Energy Site, funded by the Oregon Wave Energy Trust (OWET).