Dissertations / Theses on the topic 'Contributions in space and time'
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FERREIRA, ALINE DE OLIVEIRA. "CONTRIBUTIONS TO ARRAY SIGNAL PROCESSING: SPACE AND SPACE-TIME REDUCED-RANK PROCESSING AND RADAR-EMBEDDED COMMUNICATIONS." PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO, 2017. http://www.maxwell.vrac.puc-rio.br/Busca_etds.php?strSecao=resultado&nrSeq=30563@1.
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PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIROCOORDENAÇÃO DE APERFEIÇOAMENTO DO PESSOAL DE ENSINO SUPERIOR
PROGRAMA DE EXCELENCIA ACADEMICA
Processamento em arranjos de sensores é uma área com vasta aplicação, tanto civil quanto militar, por exemplo em sonar, radar, sismologia e comunicações sem fio. Por meio de processamento espacial e espácio-temporal é possível melhorar suas funcionalidades e explorar novas possibilidades. Esta área vem atraindo cada vez mais a atenção e os esfor¸cos da comunidade científica, especialmente agora, em que antenas phased-array se estabeleceram como uma tecnologia comercial e madura. Neste contexto, nós tratamos o problema de processamento com posto reduzido em processamento espacial (beamforming) e espácio-temporal de sinais radar e a nova área de radares com função dual de radar e comunicações (dualfunction radar-communications, DFRC), que pode ser resumida na incorporação de mensagens de comunicações nas transmissıes radar como uma tarefa secundária. Nesta tese, nós investigamos a aplicação de um novo esquema de reduções de posto baseado em interpolação e decimação em duas áreas distintas: processamento espacial e processamento espácio-temporal de sinais radar. Este algoritmo para redução de posto nunca havia sido testado nestes ambientes antes e apresentou resultados bastante expressivos. Nós também propomos simplificações para reduzir a complexidade computacional do algoritmo em bemforming. Quanto ao tópico de DFRC, nós propomos dois métodos originais para incorporar modulação de amplitude/fase aos lóbulos laterais do diagrama de irradiação do radar de forma robusta. Os métodos propostos são muito mais simples do que o estado-da-arte e apresentam desempenho superior em termos de robustez e aplicabilidade em operações de tempo-real. Nós ainda provemos várias outras análises, comparações e contribuições a esta nova área.
Array processing is an area with many civilian and military applications, e.g. sonar, radar, seismology and wireless communications. By means of space and space-time processing it is possible to enhance their features and explore new possibilities. This area has been attracting increasingly more attention and gathering more efforts of the science community, especially now, that phased array antennas are established as a commercial and mature technology. Within this context, we address the problem of reduced rank processing in space and space-time radar signal processing and the new area of dual-function radar-communications (DFRC), which may be summarized as embedding communication messages into radar emissions as a secondary task for the radar. In this thesis, we investigate the application of a new joint interpolation and decimation rank reducing scheme in two different areas: beamforming and space-time radar processing. This rank reducing algorithm was never tested within these contexts before and shows impressive results. We also propose simplifications for decreasing the computational complexity of the algorithm in beamforming. In the topic of DFRC, we propose two original robust radar-embedded sidelobe phase/amplitude modulation methods which have simple closed form equations. The proposed methods are much simpler than the state of the art and have superior performance in terms of robustness and real-time applicability.
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Schoenig, Gregory Neumann. "Contributions to Robust Adaptive Signal Processing with Application to Space-Time Adaptive Radar." Diss., Virginia Tech, 2007. http://hdl.handle.net/10919/26972.
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Classical adaptive signal processors typically utilize assumptions in their derivation. The
presence of adequate Gaussian and independent and identically distributed (i.i.d.) input
data are central among such assumptions. However, classical processors have a tendency
to suffer a degradation in performance when assumptions like these are violated. Worse
yet, such degradation is not guaranteed to be proportional to the level of deviation from
the assumptions. This dissertation proposes new signal processing algorithms based on
aspects of modern robustness theory, including methods to enable adaptivity of presently
non-adaptive robust approaches. The contributions presented are the result of research
performed jointly in two disciplines, namely robustness theory and adaptive signal process-
ing. This joint consideration of robustness and adaptivity enables improved performance in
assumption-violating scenarios â scenarios in which classical adaptive signal processors fail.
Three contributions are central to this dissertation. First, a new adaptive diagnostic tool for
high-dimension data is developed and shown robust in problematic contamination. Second,
a robust data-pre-whitening method is presented based on the new diagnostic tool. Finally,
a new suppression-based robust estimator is developed for use with complex-valued adaptive
signal processing data. To exercise the proposals and compare their performance to state-
of-the art methods, data sets commonly used in statistics as well as Space-Time Adaptive
Processing (STAP) radar data, both real and simulated, are processed, and performance is
subsequently computed and displayed. The new algorithms are shown to outperform their
state-of-the-art counterparts from both a signal-to-interference plus noise ratio (SINR) conver-
gence rate and target detection perspective.Ph. D.
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Baba, Ibrahim El. "Contributions numériques en compatibilité électromagnétique impulsionnelle. Paradigme pour la caractérisation temporelle d'équipements." Thesis, Clermont-Ferrand 2, 2012. http://www.theses.fr/2012CLF22232/document.
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Le travail présenté dans cette thèse concerne la mise en oeuvre numérique de techniques temporelles pour des applications en compatibilité électromagnétique (CEM) impulsionnelle, essentiellement pour des études en chambre réverbérante à brassage de modes (CRBM). Prenant le contre-pied des approches fréquentielles, adaptées par nature aux études de cavités résonantes, l’idée directrice de ce mémoire a été d’étudier des moyens temporels originaux d’investigation de CRBM en vue de proposer de nouveaux paradigmes pour la caractérisation d’équipements. Originellement développé en acoustique, le processus de retournement temporel (RT) récemment appliqué aux ondes électromagnétiques permet une focalisation spatiale et temporelle de ces dernières d’autant meilleur que le milieu de propagation est réverbérant. Les chambres réverbérantes (CR) sont ainsi des endroits idéaux pour l’application du processus de RT. Après une nécessaire étude des nombreux paramètres qui gouvernent ce dernier couplée à la définition de méthodologies numériques spécifiques, les applications du RT en CRBM sont exposées. En particulier, l’intérêt d’une focalisation sélective pour des tests en susceptibilité rayonnée est démontré. L’importance des coefficients d’absorption et de diffraction des équipements en CRBM justifie leur caractérisation précise et efficace. À cette fin, la mise en oeuvre d’un calcul temporel de section efficace totale de diffraction (TSCS en anglais) est détaillée. L’application de cette nouvelle technique à différentes formes de brasseurs de modes permet au final de confronter ces résultats avec ceux obtenus à l’aide de tests normatifs CEMThe work presented in this thesis concerns the use of time techniques for impulsive ElectroMagnetic Compatibility (EMC) applications, mainly for Modes Stirred Reverberation Chamber (MSRC) studies. Contrary to approaches from frequency domain, obviously well-fitted for studies in resonant cavities, the main idea of this thesis was to study an original time method for MSRC investigation to propose new paradigms for equipment characterization. Originally developed in acoustics, the Time Reversal (TR) process recently applied to electromagnetic waves allows focusing it both in time and space. The process quality is even higher if the propagation environment is reverberant. Thus, the Reverberation Chambers (RC) are an ideal locations for TR implementation. After a study of parameters involved in the TR process coupled with the definition of specific numerical methods, the applications of TR in MSRC are exposed. In particular, the interest of selective focusing for radiated susceptibility tests is demonstrated. The importance of absorption and diffraction coefficients for MSRC equipment justifies their accurate and efficient characterization. To this end, the implementation of a temporal calculation of the Total Scattering Cross Section (TSCS) in RC is detailed. The application of this new technique to different forms of stirrers allows finally to face these results with those obtained from standard EMC test
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Demir, Serhat. "Diffusion of Police Technology across Time and Space and the Impact of Technology Use on Police Effectiveness and Its Contribution to Decision-Making." Kent State University / OhioLINK, 2009. http://rave.ohiolink.edu/etdc/view?acc_num=kent1238602124.
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Guyot, Maxime. "Neutronics and thermal-hydraulics coupling : some contributions toward an improved methodology to simulate the initiating phase of a severe accident in a sodium fast reactor." Thesis, Aix-Marseille, 2014. http://www.theses.fr/2014AIXM4345.
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Le sujet de la thèse s'inscrit dans le cadre de la rénovation des outils et des méthodes de calculs appliqués aux accidents graves des Réacteurs à Neutrons Rapides refroidis au Sodium (RNR-Na). En particulier, on s'intéresse aux biais et conservatismes liés à la méthodologie de calculs de la phase primaire d'un accident grave. Pour évaluer les conséquences d'un accident de fusion du coeur d'un RNR-Na, une approche déterministe est généralement réalisée en considérant des hypothèses dites "best-estimate". Cette approche repose sur l'utilisation de codes informatiques pour simuler numériquement le comportement du coeur en conditions accidentelles.La phase primaire de dégradation concerne les évènements se produisant tant que les boîtiers inter-assemblages sont intègres. Les assemblages combustibles conservent alors une indépendance les uns par rapport aux autres. Pour cette raison, la simulation de la phase primaire repose sur une approche multi-canaux. Cette approche consiste à regrouper les assemblages semblables en classes d'assemblages appelés canaux. Le modèle thermo-hydraulique en canaux est couplé à un calcul neutronique pour évaluer le niveau de puissance et de réactivité au cours du transitoire accidentel. La méthodologie de calcul de la phase primaire d'un accident grave repose sur des hypothèses fortes en termes de modélisation neutronique et thermo-hydraulique. Après avoir identifié les principales sources d'erreur, la thèse a consisté à développer un nouvel outil de calcul pour la phase primaire en vue d'évaluer les biais et conservatismes méthodologiquesThis project is dedicated to the analysis and the quantification of bias corresponding to the computational methodology for simulating the initiating phase of severe accidents on Sodium Fast Reactors. A deterministic approach is carried out to assess the consequences of a severe accident by adopting best estimate design evaluations. An objective of this deterministic approach is to provide guidance to mitigate severe accident developments and recriticalities through the implementation of adequate design measures. These studies are generally based on modern simulation techniques to test and verify a given design. The new approach developed in this project aims to improve the safety assessment of Sodium Fast Reactors by decreasing the bias related to the deterministic analysis of severe accident scenarios.During the initiating phase, the subassembly wrapper tubes keep their mechanical integrity. Material disruption and dispersal is primarily one-dimensional. For this reason, evaluation methodology for the initiating phase relies on a multiple-channel approach. Typically a channel represents an average pin in a subassembly or a group of similar subassemblies. Inthe multiple-channel approach, the core thermal-hydraulics model is composed of 1 or 2 D channels. The thermal-hydraulics model is coupled to a neutronics module to provide an estimate of the reactor power level.In this project, a new computational model has been developed to extend the initiating phase modeling. This new model is based on a multi-physics coupling. This model has been applied to obtain information unavailable up to now in regards to neutronics and thermal-hydraulics models and their coupling
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Bouchiba, Hassan. "Contributions en traitements basés points pour le rendu et la simulation en mécanique des fluides." Thesis, Paris Sciences et Lettres (ComUE), 2018. http://www.theses.fr/2018PSLEM076/document.
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Le nuage de points 3D est la donnée obtenue par la majorité des méthodes de numérisation surfacique actuelles. Nous nous intéressons ainsi dans cette thèse à l'utilisation de nuages de points comme unique représentation explicite de surface. Cette thèse présente deux contributions en traitements basés points. La première contribution proposée est une nouvelle méthode de rendu de nuages de points bruts et massifs par opérateurs pyramidaux en espace image. Cette nouvelle méthode s'applique aussi bien à des nuages de points d'objets scannés, que de scènes complexes. La succession d'opérateurs en espace image permet alors de reconstruire en temps réel une surface et d'en estimer des normales, ce qui permet par la suite d'en obtenir un rendu par ombrage. De plus, l'utilisation d'opérateurs pyramidaux en espace image permet d'atteindre des fréquences d'affichage plus élevées d'un ordre de grandeur que l'état de l'art .La deuxième contribution présentée est une nouvelle méthode de simulation numérique en mécanique des fluides en volumes immergés par reconstruction implicite étendue. La méthode proposée se base sur une nouvelle définition de surface implicite par moindres carrés glissants étendue à partir d'un nuage de points. Cette surface est alors utilisée pour définir les conditions aux limites d'un solveur Navier-Stokes par éléments finis en volumes immergés, qui est utilisé pour simuler un écoulement fluide autour de l'objet représenté par le nuage de points. Le solveur est interfacé à un mailleur adaptatif anisotrope qui permet de capturer simultanément la géométrie du nuage de points et l'écoulement à chaque pas de temps de la simulationMost surface 3D scanning techniques produce 3D point clouds. This thesis tackles the problem of using points as only explicit surface representation. It presents two contributions in point-based processing. The first contribution is a new raw and massive point cloud screen-space rendering algorithm. This new method can be applied to a wide variety of data from small objects to complex scenes. A sequence of screen-space pyramidal operators is used to reconstruct in real-time a surface and estimate its normals, which are later used to perform deferred shading. In addition, the use of pyramidal operators allows to achieve framerate one order of magnitude higher than state of the art methods. The second proposed contribution is a new immersed boundary computational fluid dynamics method by extended implicit surface reconstruction. The proposed method is based on a new implicit surface definition from a point cloud by extended moving least squares. This surface is then used to define the boundary conditions of a finite-elements immersed boundary transient Navier-Stokes solver, which is used to compute flows around the object sampled by the point cloud. The solver is interfaced with an anisotropic and adaptive meshing algorithm which refines the computational grid around both the geometry defined by point cloud and the flow at each timestep of the simulation
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Oswald, Michael. "New contributions to space debris environment modeling." Aachen Shaker, 2008. http://d-nb.info/988549123/04.
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Karacayir, Murat. "Space-time Codes." Master's thesis, METU, 2010. http://etd.lib.metu.edu.tr/upload/12612028/index.pdf.
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The phenomenon of fading constitutes a fundamental problem in wireless communications. Researchers have proposed many methods to improve the reliability of communication over wireless channels in the presence of fading. Many studies on this topic have focused on diversity techniques. Transmit diversity is a common diversity type in which multiple antennas are employed at the transmitter. Space-time coding is a technique based on transmit diversity introduced by Tarokh et alii in 1998.
In this thesis, various types of space-time codes are examined. Since they were originally introduced in the form of trellis codes, a major part is devoted to space-time trellis codes where the fundamental design criteria are established. Then, space-time block coding, which presents a different approach, is introduced and orthogonal spacetime block codes are analyzed in some detail. Lastly, rank codes from coding theory
are studied and their relation to space-time coding are investigated.
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Dowker, Fay H. "Space-time wormholes." Thesis, University of Cambridge, 1990. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.359554.
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Lamahewa, Tharaka Anuradha, and tharaka lamahewa@anu edu au. "Space-Time Coding and Space-Time Channel Modelling for Wireless Communications." The Australian National University. Research School of Information Sciences and Engineering, 2007. http://thesis.anu.edu.au./public/adt-ANU20070816.152647.
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In this thesis we investigate the effects of the physical
constraints such as antenna aperture size, antenna geometry and
non-isotropic scattering distribution parameters (angle of
arrival/departure and angular spread) on the performance of coherent
and non-coherent space-time coded wireless communication systems.
First, we derive analytical expressions for the exact pairwise error
probability (PEP) and PEP upper-bound of coherent and non-coherent
space-time coded systems operating over spatially correlated fading
channels using a moment-generating function-based approach. These
analytical expressions account for antenna spacing, antenna
geometries and scattering distribution models. Using these new PEP
expressions, the degree of the effect of antenna spacing, antenna
geometry and angular spread is quantified on the diversity advantage
(robustness) given by a space-time code. It is shown that the number
of antennas that can be employed in a fixed antenna aperture without
diminishing the diversity advantage of a space-time code is
determined by the size of the antenna aperture, antenna geometry and
the richness of the scattering environment.
¶
In realistic channel environments the performance of space-time
coded multiple-input multiple output (MIMO) systems is significantly
reduced due to non-ideal antenna placement and non-isotropic
scattering. In this thesis, by exploiting the spatial dimension of a
MIMO channel we introduce the novel use of linear spatial precoding
(or power-loading) based on fixed and known parameters of MIMO
channels to ameliorate the effects of non-ideal antenna placement on
the performance of coherent and non-coherent space-time codes. The
spatial precoder virtually arranges the antennas into an optimal
configuration so that the spatial correlation between all antenna
elements is minimum. With this design, the precoder is fixed for
fixed antenna placement and the transmitter does not require any
feedback of channel state information (partial or full) from the
receiver. We also derive precoding schemes to exploit non-isotropic
scattering distribution parameters of the scattering channel to
improve the performance of space-time codes applied on MIMO systems
in non-isotropic scattering environments. However, these schemes
require the receiver to estimate the non-isotropic parameters and
feed them back to the transmitter.
¶
The idea of precoding based on fixed parameters of MIMO channels is
extended to maximize the capacity of spatially constrained dense
antenna arrays. It is shown that the theoretical maximum capacity
available from a fixed region of space can be achieved by power
loading based on previously unutilized channel state information
contained in the antenna locations. We analyzed the correlation
between different modal orders generated at the transmitter region
due to spatially constrained antenna arrays in non-isotropic
scattering environments, and showed that adjacent modes contribute
to higher correlation at the transmitter region. Based on this
result, a power loading scheme is proposed which reduces the effects
of correlation between adjacent modes at the transmitter region by
nulling power onto adjacent transmit modes.
¶
Furthermore, in this thesis a general space-time channel model for
down-link transmission in a mobile multiple antenna communication
system is developed. The model incorporates deterministic
quantities such as physical antenna positions and the motion of the
mobile unit (velocity and the direction), and random quantities to
capture random scattering environment modeled using a bi-angular
power distribution and, in the simplest case, the covariance between
transmit and receive angles which captures statistical
interdependency. The Kronecker model is shown to be a special case
when the power distribution is separable and is shown to
overestimate MIMO system performance whenever there is more than one
scattering cluster. Expressions for space-time cross correlations
and space-frequency cross spectra are given for a number of
scattering distributions using Gaussian and Morgenstern's family of
multivariate distributions. These new expressions extend the
classical Jake's and Clarke's correlation models to general
non-isotropic scattering environments.
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Lamahewa, Tharaka Anuradha. "Space-time coding and space-time channel modelling for wireless communications /." View thesis entry in Australian Digital Theses Program, 2006. http://thesis.anu.edu.au/public/adt-ANU20070816.152647/index.html.
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Haron, Linariza. "Facility space-time management." Thesis, University College London (University of London), 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.326152.
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Thompson, Philip R. Z. (Philip Reed Zane). "Space, time and acoustics." Thesis, Massachusetts Institute of Technology, 1988. http://hdl.handle.net/1721.1/78997.
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Thesis (M. Arch.)--Massachusetts Institute of Technology, Dept. of Architecture, 1988.Includes bibliographical references (leaves 156-159).
This thesis describes the development of new concepts in acoustical analysis from their inception to implementation as a computer design tool. Research is focused on a computer program which aids the designer to visually conceive the interactions of acoustics within a geometrical~y defined environment by synthesizing the propagation of sound in a three dimensional space over time. Information is communicated through a unique use of images that are better suited for interfacing with the design process. The first part of this thesis describes the concepts behind the development of a graphic acoustical rendering program to a working level. This involves the development of a computer ray tracing prototype that is sufficiently powerful to explore the issues facing this new design and analysis methodology. The second part uses this program to evaluate existing performance spaces in order to establish qualitative criteria in a new visual format. Representational issues relating to the visual perception of acoustic spaces are also explored. In the third part, the program is integrated into the design process. I apply this acoustical tool to an actual design situation by remodeling a large performance hall in Medford, Massachusetts. Chevalier Auditorium is a real project, commissioned by the city of Medford, whose program requirements closely match my intentions in scope, scale and nature of a design for exploring this new acoustical analysis and design methodology. Finally, I summarize this program's effectiveness and discuss its potential in more sophisticated future design environments.
by Philip R.Z. Thompson.
M.Arch.
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Sanders, Ralph Jarrett. "Space, time, and silence." Thesis, Virginia Polytechnic Institute and State University, 1990. http://hdl.handle.net/10919/56200.
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This thesis is a meditation upon silence, upon its ontological relationship to architecture. As such, it relies more upon insight and contemplation than analysis. It seeks to explore this realm through the making of a trappist monastery, to ask fundamental questions about the nature of human dwelling in the most complete sense, to stir the memory and perhaps to move the heart toward that silence which is beyond thought, which precedes and bounds and yet pervades all human experience.Master of Architecture
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Pak, Anne On-Yi 1977. "Euclidean space codes as space-time block codes." Thesis, Massachusetts Institute of Technology, 2001. http://hdl.handle.net/1721.1/86722.
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Kamela, Martin J. "Space-time duality, superduality, and effective actions on anti-de-Sitter space-time." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1999. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp03/NQ64585.pdf.
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盧燦霖 and Chan-lam Lo. "Some contributions to robust time series modelling." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 1987. http://hub.hku.hk/bib/B31207807.
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Lo, Chan-lam. "Some contributions to robust time series modelling /." [Hong Kong : University of Hong Kong], 1987. http://sunzi.lib.hku.hk/hkuto/record.jsp?B12388063.
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Mian, Ammar. "Contributions to SAR Image Time Series Analysis." Thesis, Université Paris-Saclay (ComUE), 2019. http://www.theses.fr/2019SACLC074/document.
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La télédétection par Radar à Synthèse d’Ouverture (RSO) offre une opportunité unique d’enregistrer, d’analyser et de prédire l’évolution de la surface de la Terre. La dernière décennie a permis l’avènement de nombreuses missions spatiales équipées de capteurs RSO (Sentinel-1, UAVSAR, TerraSAR X, etc.), ce qui a engendré une rapide amélioration des capacités d’acquisition d’images de la surface de la Terre. Le nombre croissant d’observations permet maintenant de construire des bases de données caractérisant l’évolution temporelle d’images, augmentant considérablement l’intérêt de l’analyse de séries temporelles pour caractériser des changements qui ont lieu à une échelle globale. Cependant, le développement de nouveaux algorithmes pour traiter ces données très volumineuses est un défi qui reste à relever. Dans ce contexte, l’objectif de cette thèse consiste ainsi à proposer et à développer des méthodologies relatives à la détection de changements dans les séries d’images ROS à très haute résolution spatiale.Le traitement de ces séries pose deux problèmes notables. En premier lieu, les méthodes d’analyse statistique performantes se basent souvent sur des données multivariées caractérisant, dans le cas des images RSO, une diversité polarimétrique, interférométrique, par exemple. Lorsque cette diversité n’est pas disponible et que les images RSO sont monocanal, de nouvelles méthodologies basées sur la décomposition en ondelettes ont été développées. Celles-ci permettent d’ajouter une diversité supplémentaire spectrale et angulaire représentant le comportement physique de rétrodiffusion des diffuseurs présents la scène de l’image. Dans un second temps, l’amélioration de la résolution spatiale sur les dernières générations de capteurs engendre une augmentation de l’hétérogénéité des données obtenues. Dans ce cas, l’hypothèse gaussienne, traditionnellement considérée pour développer les méthodologies standards de détection de changements, n’est plus valide. En conséquence, des méthodologies d’estimation robuste basée sur la famille des distributions elliptiques, mieux adaptée aux données, ont été développées.L’association de ces deux aspects a montré des résultats prometteurs pour la détection de changements.Le traitement de ces séries pose deux problèmes notables. En premier lieu, les méthodes d’analyse statistique performantes se basent souvent sur des données multivariées caractérisant, dans le cas des images RSO, une diversité polarimétrique ou interférométrique, par exemple. Lorsque cette diversité n’est pas disponible et que les images RSO sont monocanal, de nouvelles méthodologies basées sur la décomposition en ondelettes ont été développées. Celles-ci permettent d’ajouter une diversité spectrale et angulaire supplémentaire représentant le comportement physique de rétrodiffusion des diffuseurs présents la scène de l’image. Dans un second temps, l’amélioration de la résolution spatiale sur les dernières générations de capteurs engendre une augmentation de l’hétérogénéité des données obtenues. Dans ce cas, l’hypothèse gaussienne, traditionnellement considérée pour développer les méthodologies standards de détection de changements, n’est plus valide. En conséquence, des méthodologies d’estimation robuste basée sur la famille des distributions elliptiques, mieux adaptée aux données, ont été développées.L’association de ces deux aspects a montré des résultats prometteurs pour la détection de changementsRemote sensing data from Synthetic Aperture Radar (SAR) sensors offer a unique opportunity to record, to analyze, and to predict the evolution of the Earth. In the last decade, numerous satellite remote sensing missions have been launched (Sentinel-1, UAVSAR, TerraSAR X, etc.). This resulted in a dramatic improvement in the Earth image acquisition capability and accessibility. The growing number of observation systems allows now to build high temporal/spatial-resolution Earth surface images data-sets. This new scenario significantly raises the interest in time-series processing to monitor changes occurring over large areas. However, developing new algorithms to process such a huge volume of data represents a current challenge. In this context, the present thesis aims at developing methodologies for change detection in high-resolution SAR image time series.These series raise two notable challenges that have to be overcome:On the one hand, standard statistical methods rely on multivariate data to infer a result which is often superior to a monovariate approach. Such multivariate data is however not always available when it concerns SAR images. To tackle this issue, new methodologies based on wavelet decomposition theory have been developed to fetch information based on the physical behavior of the scatterers present in the scene.On the other hand, the improvement in resolution obtained from the latest generation of sensors comes with an increased heterogeneity of the data obtained. For this setup, the standard Gaussian assumption used to develop classic change detection methodologies is no longer valid. As a consequence, new robust methodologies have been developed considering the family of elliptical distributions which have been shown to better fit the observed data.The association of both aspects has shown promising results in change detection applications
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Oswald, Michael [Verfasser]. "New Contributions to Space Debris Environment Modeling / Michael Oswald." Aachen : Shaker, 2008. http://d-nb.info/1162790970/34.
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Belda, Santiago. "Contributions to the Earth Monitoring by Space Geodesy Methods." Doctoral thesis, Universidad de Alicante, 2015. http://hdl.handle.net/10045/50535.
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Grun, Rainer Wolfgang. "Contributions to quaternary geochronology." Phd thesis, Canberra, ACT : The Australian National University, 1995. http://hdl.handle.net/1885/145307.
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Liesenjohann, Thilo. "Foraging in space and time." Phd thesis, Universität Potsdam, 2010. http://opus.kobv.de/ubp/volltexte/2010/4856/.
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All animals are adapted to the environmental conditions of the habitat they chose to live in. It was the aim of this PhD-project, to show which behavioral strategies are expressed as mechanisms to cope with the constraints, which contribute to the natural selection pressure acting on individuals. For this purpose, small mammals were exposed to different levels and types of predation risk while actively foraging. Individuals were either exposed to different predator types (airborne or ground) or combinations of both, or to indirect predators (nest predators). Risk was assumed to be distributed homogeneously, so changing the habitat or temporal adaptations where not regarded as potential options. Results show that wild-caught voles have strategic answers to this homogeneously distributed risk, which is perceived by tactile, olfactory or acoustic cues. Thus, they do not have to know an absolut quality (e.g., in terms of food provisioning and risk levels of all possible habitats), but they can adapt their behavior to the actual circumstances. Deriving risk uniform levels from cues and adjusting activity levels to the perceived risk is an option to deal with predators of the same size or with unforeseeable attack rates. Experiments showed that as long as there are no safe places or times, it is best to reduce activity and behave as inconspicuous as possible as long as the costs of missed opportunities do not exceed the benefits of a higher survival probability. Test showed that these costs apparently grow faster for males than for females, especially in times of inactivity. This is supported by strong predatory pressure on the most active groups of rodents (young males, sexually active or dispersers) leading to extremely female-biased operative sex ratios in natural populations.
Other groups of animals, those with parental duties such as nest guarding, for example, have to deal with the actual risk in their habitat as well. Strategies to indirect predation pressure were tested by using bank vole mothers, confronted with a nest predator that posed no actual threat to themselves but to their young (Sorex araneus). They reduced travelling and concentrated their effort in the presence of shrews, independent of the different nutritional provisioning of food by varying resource levels due to the different seasons. Additionally, they exhibited nest-guarding strategies by not foraging in the vicinity of the nest site in order to reduce conspicuous scent marks. The repetition of the experiment in summer and autumn showed that changing environmental constraints can have a severe impact on results of outdoor studies. In our case, changing resource levels changed the type of interaction between the two species.
The experiments show that it is important to analyze decision making and optimality models on an individual level, and, when that is not possible (maybe because of the constraints of field work), groups of animals should be classified by using the least common denominator that can be identified (such as sex, age, origin or kinship). This will control for the effects of the sex or stage of life history or the individual´s reproductive and nutritional status on decision making and will narrow the wide behavioral variability associated with the complex term of optimality.Das Verhalten von Tieren ist das Ergebnis eines kontinuierlichen Anpassungsprozesses im Laufe der Evolution einer Art und damit der Veränderung der Umgebung in der es lebt und der Interaktion mit anderen Arten. Dies wird besonders deutlich im Verhalten von potentiellen Beutetieren, ihre Strategien beinhalten meist ein möglichst unauffälliges Verhalten im Zusammenspiel mit reduzierter Bewegung und möglichst guter Tarnung. Dementgegen stehen essentielle Bedürfnisse, wie zum Beispiel die Nahrungssuche, die Verteidigung von Ressourcen (zum Beispiel Territorien, Futterstellen) und die Suche nach Paarungspartnern. Beutetiere leben also in einem Spannungsfeld indem sie Ihr Verhalten optimieren müssen. Hierbei stehen die Ernährung, erfolgreiche Verpaarung und andere Chancen auf der einen Seite, die Vermeidung von Begegnungen mit Prädatoren auf der anderen. Vor allem Kleinsäuger sind häufig als Beutetiere mit einer Vielzahl von Prädatoren aus der Luft und auf dem Boden konfrontiert. Sie müssen für die verschiedenen Bedrohungen adaptive Verhaltensanpassungen bereit haben und in der Lage sein, auf die optischen, olfaktorischen oder akustischen Signale, die die Gefahr durch Prädatoren anzeigen, mit plastischen Verhaltensmustern zu reagieren. Die vorliegende Dissertation beschäftigt sich mit bisher als Konstanten behandelten Faktoren und untersucht anhand von Verhaltensexperimenten mit wilden Wühlmäusen (Microtus arvalis) folgende Fragestellungen: - Wie verhalten sich Tiere, die einer homogenen Risikoverteilung ausgesetzt sind, zum Beispiel weil ihr Prädator genauso gross ist wie sie, im gleichen Habitat lebt und es keinen sicheren Ort gibt? - Mit welchen Anpassungen reagieren Tiere, wenn sie gleichzeitig verschiedenen Prädatoren ausgesetzt sind? - Wie unterscheiden sich die Nahrungssuchstrategien von Männchen und Weibchen? - Wie verhalten sich laktierende Weibchen, die einer permanenten, indirekten Gefahr, z.B. durch einen Nestprädator ausgesetzt sind? Die Ergebnisse der verschiedenen Versuche in künstlichen Arenen und Aussengehegen zeigen, dass die Mäuse in der Lage sind, adaptive Verhaltensanpassung an homogenes Risiko und verschiedene Prädationstypen abzurufen. So sind sie in der Lage, Luft- von Bodenprädatoren zu unterscheiden und jeweils das Verhalten zu zeigen, dass die größtmögliche Sicherheit mit sich bringt. Die simultane Kombination von verschiedenen Prädatoren bewirkt hierbei additive Effekte. Gibt es keine Auswahl zwischen Habitaten, sondern nur unterschiedliche homogene Risikolevel, reagieren sie auf steigendes Risiko immer mit verminderter Aktivität und konzentrieren ihre Nahrungssuche auf weniger Futterstellen, beuten diese dafür jedoch länger aus. Die Wertigkeit von Futterstellen und alternativen Optionen verändert sich also mit dem Risikolevel. Ähnliches zeigt sich auch in den unterschiedlichen Futtersuchstrategien von Männchen und Weibchen. Die untersuchte Art ist polygyn und multivoltin, dementsprechend verbinden die Männchen mit ihrer Nahrungssuche Aktivitäten wie die Suche nach Paarungspartnern und unterscheiden sich die Aktivitätsmuster zwischen Männchen und Weibchen. Zusätzlich zeigen die Ergebnisse, das laktierende Weibchen in der Lage sind, das Risiko für sich und für Ihre Jungen abzuschätzen, wenn sie mit einem Nestprädator (Sorex araneus) konfrontiert werden. Für die Interaktion zwischen diesen beiden Arten ist jedoch die Saison (und damit die Ressourcenlage), in der sie sich begegnen, von entscheidender Bedeutung. Wühlmäuse reagieren mit entsprechenden Verhaltensanpassungen zum Schutz des Nestes um die Überlebenschancen ihrer letzten Würfe im Herbst zu erhöhen. Die vorliegende Arbeit konnte grundsätzliche Probleme der antiprädatorischen Verhaltensanpassung von Beutetieren klären und wichtige Faktoren der Entscheidungsfindung unter Prädationsdruck analysieren. Sie zeigt, dass Tiere das Risiko in ihrer Umgebung nicht unbedingt über direkt Signale wahrnehmen, sondern ihre Verhaltensstrategien einem empfundenen Gesamtrisikolevel anpassen. Dies ermöglicht ihnen, adaptive Strategien zu verfolgen, auch wenn sie keine Auswahl an sicheren Habitaten haben. Sie zeigt auch die unterschiedliche Wahrnehmung von Risiken durch Männchen und Weibchen, die durch die unterschiedlichen mit der Aktivität zusätzlich wahrgenommenen Chancen verknüpft zu sein scheint. Zusätzlich wurde der Einfluss des reproduktiven Status (z.B. laktierend), sowie der Ressourcenlage (z. B. je nach Saison) nachgewiesen.
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Silvester, Anna-Marie. "Space-time continuous phase modulation." Thesis, University of British Columbia, 2009. http://hdl.handle.net/2429/14721.
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The combination of Space-Time (ST) coding and Continuous-Phase Modulation (CPM) produces a low power, energy efficient communication scheme suitable for wireless transmission. Space-time coding increases the reliability of transmission, and continuous-phase modulation (CPM) has the
potential to provide considerable energy savings. CPM is a modulation technique that involves the transmission of a signal with continuous-phase and a constant envelope, where the continuous-phase property produces a very bandwidth efficient signal, and the constant-envelope property enables non
linear (and thus energy efficient) signal amplification. The ST-CPM code is of special interest for wireless sensors because in the wireless sensor network environment energy consumption is highly constrained. The combination of ST codes and CPM is non-trivial and thus ST-CPM codes based upon
block-based orthogonal and diagonal signal matrices are presented. These codes are forms the basis of a distributed ST-CPM code. The distributed ST codes are designed to operate in wireless networks containing a large set of nodes, of which only a small a priori unknown subset will be active at any
time. The devised distributed ST-CPM scheme combines the ST-CPM code with a diagonal signaling matrix, (commonly assigned to all relay nodes) with signature vectors(uniquely assigned to nodes). The energy consumption of the proposed distributed ST-CPM scheme is compared with that of a distributed ST linear modulation (LM) scheme. The distributed ST-CPM scheme is shown to
outperform the distributed ST-LM scheme for all but short-range transmission. Finally, a serially concatenated code for ST-CPM is proposed. The concatenated code consists of the diagonal signalling matrix as the inner code, and a class of double parity check (DPC) codes as the outer code. The
resulting concatenated codes that are formed from the ST-CPM code and a DPC code are shown to provide performance close to capacity, and to provide performance superior to that provided by the more common combination of CPM, or ST-CPM schemes with convolutional codes.
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South-Dickinson, Ian James. "Globally consistent space-time reconstruction." Thesis, University of British Columbia, 2012. http://hdl.handle.net/2429/43207.
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We present a novel algorithm for space-time reconstruction of deforming meshes. Based on partial meshes at every frame, and sparse optical flow information between frames, we reconstruct a globally consistent, crossparameterized, and hole filled sequence of meshes. Our method is based on pair-wise merging of frame sequences while correcting for changes in topology, filling in missing geometry, and repairing inconsistencies. We also introduce a robust method for filling in missing geometry in each frame of the sequence using geometry from another frame. Using this method we can propagate geometry over the full frame sequence, correcting errors and filling in holes even in regions of the object that are not observed in the input meshes for extended periods of time. Unlike other approaches, our method does not require template geometry, nor is it limited to narrow classes of objects or purely isometric deformations.
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Yang, Ho. "Partially adaptive space-time processing." Diss., Georgia Institute of Technology, 1998. http://hdl.handle.net/1853/13028.
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Seliktar, Yaron. "Space-time adaptive monopulse processing." Diss., Georgia Institute of Technology, 1998. http://hdl.handle.net/1853/13075.
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Holm, Jens Christian. "Spinors in discrete space-time." Thesis, Georgia Institute of Technology, 1985. http://hdl.handle.net/1853/27901.
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Ramlochand, John. "Japanese cinema : time space nation." Thesis, McGill University, 2006. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=102159.
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This work utilizes a spatial theory approach to meditate on postwar Japanese society and cinema. It is not a history of Japanese postwar cinema, or a survey of notable directors and genres. Rather, the focus is specifically on film and its relation to the deeper tropes of Japanese society; in particular, on how the sense of nation is affirmed and/or challenged within a postwar period of remarkable change. Understanding such a structure greatly aids in analyzing the forms and meanings within the films. The question of National Cinema, then, is approached by exploring how the interaction of spatial-temporal elements affect both the social construction and filmic practices of the nation.The first part of the dissertation features an extended analysis of Japanese society using a variety of historical, philosophical and theoretical sources, both Japanese and foreign. They provide a theoretical base and a social history that ground the critical readings of the selected films; all of which are well-known and widely available. Part two is a close textual analysis of five 1950s productions---from a range of films and genres---that are contrasted with three films from the late 1980s/early 1990s. The final chapter examines notions about National Cinema in light of the preceding film analysis.
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Mason, Lionel J. "Twistors in curved space time." Thesis, University of Oxford, 1985. http://ora.ox.ac.uk/objects/uuid:29de7cd1-84c9-4374-8f7d-9a402dd9e0ed.
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This thesis is concerned with an investigation of twistorial structures present in curved Lorentzian space-times. Chapter 1 introduces the basic definitions and some theorems that will be used later in the text. Chapter 2 investigates generalised connections that arise in twister theory. First the Cartan con-formal connection is studied, and some of the geometry underlying it is shown to be that used by Fefferman and Graham C133. Also a condition that a space-time is conformal to vacuum is given. Secondly the theory of the Chern connection associated to a C.R. manifold is developed in such a way as to make the calculation of the connection associated to a twistor C.R. manifold straight forward. A new proof of the Chern theorem of existence and uniqueness is given. The Chern connection of a twistor C.R. manifold is then calculated, and discussed. In particular S-dimensionai C.R. manifolds arising as twistor C.R. manifolds are characterised. Canonical structures peculiar to the twister case are discussed. Applications of C.R. manifold theory to algebraically special space-times are suggested. Chapter three analyses how various twistorial structures behave in linearised general relativity. First, deformations of the space of complex null geodesies corresponding to variations of the conformal structure of space-time are shown to be generated by hami1tonians. Those that correspond to variations in the metric satisfying the field equations are given, along with hamiltonians corresponding to different fields and field equations. Beneralisations to nonlinear equations are discussed. These ideas are applied to hypersurface twisters in linearised theory, using fiat hypersurfaces and Cech cohoeology. Expressions are obtained for the deformation of the complex structure of the spaces and their evolution. The results are generalised to non flat hypersurfaces using Dolbeault cohomolcgy. It is shown that certain canonically defined forms on the spin bundle are preferred Dolbeault representatives for derivatives of the twister cohomology classes corresponding to the linearised field. In chapter four I generalise the results of chapter three to curved space using the Chern connection. In particular twistorial formulations of the constraint equations are given, and a formula for the evolution that satisfies the the vacuum evolution equations is given in terms of an "infinity" twistor and a "time" twister. This is then discussed. In chapter five I make some comments on the interpretation of a three form on the spin bundle discovered by B.A.J. Sparling as the gravitational hami1tonian. I then use this to show that one can give an interpretation of Penrose's quasi-local angular momentum twistor in terms of the canonical formalism.
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Dang, Xiaoyu. "Space-Time Shaped Offset QPSK." International Foundation for Telemetering, 2008. http://hdl.handle.net/10150/606190.
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ITC/USA 2008 Conference Proceedings / The Forty-Fourth Annual International Telemetering Conference and Technical Exhibition / October 27-30, 2008 / Town and Country Resort & Convention Center, San Diego, CaliforniaThis paper describes the use of orthogonal space-time block codes to overcome the performance and complexity difficulties associated with the use of Shaped Offset QPSK (SOQPSK) modulation, a ternary continuous phase modulation (CPM), in multiple-input multiple-output telemetry systems. The orthogonal space-time block code is applied to SOQPSK waveforms in the same way it would be applied to symbols. The procedure allows the receiver to orthogonalize the link. The main benefits of this orthogonalization are the easy realization of the transmit diversity for the offset-featured SQOSPK, and the removal of the noise correlation at the input to the space-time decoder and the elimination of I/Q interference when space time orthogonalization is applied to the symbol level.
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Asbell, Jonathan Clark. "Thresholds in Space and Time." Thesis, Virginia Tech, 2020. http://hdl.handle.net/10919/100920.
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In architecture there is perhaps no better opportunity to capture movement and change than in the design of thresholds. They can be a simple strip of metal beneath a doorway, barely noticed as you pass over it, or a grand atrium that you stop and marvel at on your way into the office. They can manifest as a change of materials or finishes, or of some parameter such as ceiling height. They might even be immaterial altogether, like the boundary between light and shadow.
Thresholds transcend the physical to effect a psychological experience. They can be spatial or temporal or some combination of the two, but whatever form they take, all thresholds can be said to be mediators of our movement from one spatial status to another. Inside to outside, public to private, here to there. Too often our buildings relegate these changes to doors or openings that have little connection to the buildings they are a part of, and so our awareness of passage from space to space is diminished. This thesis explores ways to enrich the architecture of the threshold so that it doesn't merely recede to the bounds of our perception.Master of Architecture
The term "threshold" often brings to mind a strip of material at the base of a doorway, but architecture considers thresholds more broadly as moments of movement or change. This thesis examines such moments in an original building design, proposing several threshold types and exploring their impact on occupants.
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Boué, Stéphanie. "Transcripts in space and time." Université Louis Pasteur (Strasbourg) (1971-2008), 2006. https://publication-theses.unistra.fr/public/theses_doctorat/2006/BOUE_Stephanie_2006.pdf.
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Les biologistes moléculaires cherchent à comprendre comment fonctionnent les organismes au niveau moléculaire. Le but ultime de ces recherches est d’offrir la possibilité de manipuler sans risque des cellules et/ou des organismes afin de combattre des maladies génétiques, d’éradiquer les maladies contagieuses ou par exemple d’améliorer les qualités nutritives de l’alimentation. Actuellement, la manière la plus précise et pratique de comprendre le fonctionnement d’un organisme est d’étudier son transcriptome et ses variations dans l’espace et le temps. Suivant cette logique, le but de ma thèse de doctorat a été double: (1) estimer l’importance de l’épissage alternatif qui engendre une diversité des transcripts (2) étudier les transcriptomes de deux organismes modèles : Mus musculus et Drosophila melanogaster, respectivement dans l’espace et le temps. Durant ces années de recherche, j’ai rassemblé des découvertes intéressantes concernant l’expression des gènes et sa régulation. D’abord, l’épissage alternatif s’est avéré être un méchanisme important non seulement en terme de fréquence (des transcripts alternatifs sont générés pour une vaste majorité des gènes, et ce dans de multiples espèces), mais aussi en terme d’évolution (l’épissage alternatif semble permettre à un gène d’évoluer sans conséquences trop négatives pour l’organisme). Par ailleurs nous avons prouvé que le niveau d’expression de transcripts n’est pas en soi synonyme de fonction: il y a en effet une quantité non négligeable d’expression neutre, qui doit être prise en compte lors de l’assignation d’une fonction à un gène, uniquement basée sur la similarité de son profil d’expression par rapport à celui d’un gène de fonction connue. Enfin, nous avons étudié des séries de puces à ADN appliquées à l’embryogenèse de la mouche dans le temps, en utilisant une technique non conventionnelle pour ce type d’approche. Nous avons réparti les gènes en différentes classes selon leurs profils d’expression. Nous avons pu prouver que ces classes de gènes ont des critères biologiques en commun, ce qui laisse supposer que les gènes inconnus ou mal caractérisés qui tombent dans ces classes sont d’interessants points de départ pour de futures recherches. Des découvertes inestimables ont été et seront encore faites en biologie moléculaire grâce à l’étude des transcriptomes dans des organismes variés, analysés dans différentes conditions. Cependant, il est devenu clair qu’à cause de la présence de nombreuses étapes de régulation après la transcription, dont l’épissage alternatif, seule l’analyse des protéomes permettra d’obtenir une vision complète de la biologie de la cellule.
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Mangitli, Irem. "Infinity in time and space." College Park, Md. : University of Maryland, 2004. http://hdl.handle.net/1903/1458.
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Thesis (M.F.A.) -- University of Maryland, College Park, 2004.Thesis research directed by: Dept. of Art. Title from t.p. of PDF. Includes bibliographical references. Published by UMI Dissertation Services, Ann Arbor, Mich. Also available in paper.
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Boué, Stéphanie Stévenin James Bork Peer. "Transcripts in space and time." Strasbourg : Université Louis Pasteur, 2006. http://eprints-scd-ulp.u-strasbg.fr:8080/499/01/Boue_PhD_Transcripts_Space_Time_2006.pdf.
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Ghosh, Sourav. "Thermodynamics of Margulis Space Time." Thesis, Paris 11, 2015. http://www.theses.fr/2015PA112137/document.
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Dans ma thèse, je décris les feuilles stables et instables pour le flot géodésique sur l’espace des géodésiques non-errant de type espace d’un espace-temps de Margulis et je démontre des propriétés de contraction des feuilles sous le flot. Je montre aussi que la monodromie d’un espace-temps de Margulis est une représentation Anosov dans un groupe de Lie non semisimple. En outre, je montre que les applications limites et reparamétrisation varient analytiquement. Enfin, à l’aide de la propriété métrique Anosov, nous définissons la métrique de pression sur l’espace modulaire des espaces-temps de Margulis sans pointes et je démontre qu’elle est définie positive sur les sections d’entropie constanteIn my thesis I describe the stable and unstable leaves for the geodesic flow on the space of non-wandering spacelike geodesics of a Margulis Space Time and prove contraction properties of the leaves under the flow. I also show that monodromy of Margulis Space Times are “Anosov representations in non semi-simple Lie groups”. Moreover, I show that the limit maps and reparametrizations vary analytically. Finally using the metric Ansosov property we define the Pressure metric on the Moduli Space of Margulis Space Times without “cusps” and show that it is positive definite on the constant entropy sections
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Błachuta, Marian. "Contributions to the theory of discrete-time control for continous-time system." Praca habilitacyjna, Wydawnictwo Politechniki Śląskiej, 1999. https://delibra.bg.polsl.pl/dlibra/docmetadata?showContent=true&id=7687.
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Shao, Qinglong. "Recession, working time and environmental pressure: econometric contributions." Doctoral thesis, Universitat Autònoma de Barcelona, 2017. http://hdl.handle.net/10803/405659.
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El objetivo principal de esta tesis es investigar los efectos del tiempo de trabajo y la recesión económica sobre el medio ambiente y especialmente sobre las emisiones de carbono. Esto se lleva a cabo a través de cinco estudios originales. Los dos primeros análisis (capítulos 2 y 3) examinan el impacto de la recesión económica sobre las emisiones de carbono y los flujos de materiales. El primer estudio demuestra que globalmente al menos unos 31.34 Gt de emisiones de CO2 han sido evitadas debido a recesiones económicas desde 1960. Las recesiones son el factor más determinante de las reducciones de carbono, pero su efecto por sí solo no marcará la diferencia en el objetivo de mantener en menos de 2°C el incremento global de temperatura. El segundo estudio, basado en un análisis histórico de datos de panel de 150 países, encuentra que los períodos de recesión están significativamente asociados con la desmaterialización absoluta. Sin embargo, cuanto mayor fue el crecimiento del PIB, menos significativa fue la correlación. La correlación significativa desaparece cuando la tasa de crecimiento supera al 2%. Los minerales y metales utilizados a granel para la construcción parecen ser más sensibles a las fluctuaciones económicas que la biomasa y los combustibles fósiles.
Las tres contribuciones siguientes (capítulos 4, 5 y 6) investigan posibles relaciones lineales y no lineales entre las horas de trabajo y la presión medioambiental. El tercer estudio encuentra una correlación negativa significativa entre el tiempo de trabajo y la presión ambiental para los países desarrollados, lo que contradice estudios previos, según los cuales la reducción del tiempo de trabajo mejora el medio ambiente. El cuarto estudio avanza el análisis dividiendo una muestra mundial en grupos de países desarrollados y en desarrollo y dividiendo el período de investigación en dos fases, antes y después del año 2000. Los resultados no muestran una correlación significativa entre el tiempo de trabajo y la carga medioambiental en las economías en desarrollo; no obstante, en las economías desarrolladas se produce un "efecto rebote". La relación significativa entre las horas de trabajo y la presión medioambiental pasa de positiva a negativa después del año 2000, en parte debido a que las personas que viven en países más ricos prefieren actividades de elevado consumo energético en sus horas de ocio, como viajar largas distancias en coche o hacer vacaciones en el extranjero. Sobre la base de estos hallazgos, el quinto y último estudio concluye que hasta 2010, entre los países de la UE15, una nueva reducción del tiempo de trabajo en Dinamarca, Alemania, Francia y los Países Bajos puede comenzar a dañar el medio ambiente.The main aim of this thesis is to investigate the effects of working time and economic recession on the environment, especially on carbon emissions. This is attained through five original studies. The first two analyses (chapter 2 and 3) examine the impact of economic recession on carbon emissions and material flows. The first study concludes that on a global scale, at least 31.34 Gt of CO2 emissions have been avoided due to economic recessions since 1960. Recessions are the most determinant factor of carbon reductions, but their effect alone is not sufficient to meet the objective of staying below a 2°C global temperature change. The second study, based on a historical panel data analysis of 150 countries, finds that periods of recession are significantly associated with absolute dematerialization. However, the higher the growth of GDP, the less significant we have found the correlation to be. The significant correlation disappears when the growth rate is higher than 2%. Minerals and metals used in bulk for construction appear to be more sensitive to economic fluctuations than biomass and fossil fuels. The next three contributions (chapters 4, 5 and 6) investigate possible linear as well as non-linear relationships between hours of work and environmental pressure. The third study finds a significant negative correlation between working time and environmental pressure for developed countries, which is contrary to prior research, according to which shorter working hours improve the environment. The fourth study advances the analysis by dividing a world sample into developed and developing country groups and splitting the research period into two phases, before and after the year 2000. The results show no significant correlation between working time and environmental burden in developing economies, however in their developed counterparts, a “rebound effect” occurs. The significant relationship between hours of work and environmental pressure turns from positive to negative after 2000, partly because residents in wealthier countries prefer more energy-intensive activities in their leisure time, such as long-distance car traveling or vacations abroad. Based on these findings, the fifth and final study concludes that until 2010, among the EU-15 countries, further reductions in working hours in Denmark, Germany, France and the Netherlands may start having a negative impact on the environment.
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Olsson, Mattias. "Contributions to Frequency Offset and Time Delay Estimation." Licentiate thesis, Linköping : Linköping University, 2006. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-6436.
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Hung, Ying. "Contributions to computer experiments and binary time series." Diss., Atlanta, Ga. : Georgia Institute of Technology, 2008. http://hdl.handle.net/1853/24707.
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Thesis (Ph.D.)--Industrial and Systems Engineering, Georgia Institute of Technology, 2008.Committee Chair: C. F. Jeff Wu; Committee Co-Chair: Roshan Joseph Vengazhiyil; Committee Member: Kwok L. Tsui; Committee Member: Ming Yuan; Committee Member: Shreyes N. Melkote
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Rivera, Monica Alexandra. "Slowing Down Time, studies on spatial time." Thesis, Virginia Tech, 2006. http://hdl.handle.net/10919/33992.
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The experience of time is not fixed by a rigid mathematical measure, instead, it flows at vaying rates.
There are certain occasions in which we would like to extend time with all our force, up to the limit of our stretched arms and further. Conversely there are moments which we'd like to last no more that the sparkle of a flash, but as we all have noticed, those are the longest in our life.
How does the space that we inhabit influence on our perception of time? May we identify especial elements that contribute in one or other sense to accelerate or slowdown the time?
It's said that time and space is an inseparable unity, as two aspects of the same thing. If this is so, then it also must be true that by shaping space in one way or another, we might influence the experience of time through it. Wouldn't it be delightful to believe that we may be magicians of time through manipulation of architecture?Master of Architecture
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Acharya, Om Nath, and Sabin Upadhyaya. "Space Time Coding For Wireless Communication." Thesis, Linnéuniversitetet, Institutionen för datavetenskap, fysik och matematik, DFM, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:lnu:diva-19424.
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As the demand of high data rate is increasing, a lot of research is being conducted in the field of wireless communication. A well-known channel coding technique called Space-Time Coding has been implemented in the wireless Communication systems using multiple antennas to ensure the high speed communication as well as reliability by exploiting limited spectrum and maintaining the power. In this thesis, Space-Time Coding is discussed along with other related topics with special focus on Alamouti Space-Time Block Code. The Alamouti Codes show good performance in terms of bit error rate over Rayleigh fading channel. The performance of Altamonte’s code and MIMO capacity is evaluated by using MATLAB simulation.
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Healy, Eithne. "Allegories of space : allegories of time." Thesis, University of East London, 2008. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.532879.
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Taking identity as a point of departure, I examine specific cultural and philosophical concerns relating to ideas of alienation, and consider the impact of buildings and space - and their more universal implications - on the formation of historical, psychological and social perceptions of (the) `self. My research has introduced me to new writers, theorists and practitioners including Anthony Vidler's meditations on the spatial and emotional anxieties that architecture evokes. - Artists and filmmakers I refer to include, Anslem Kiefer, Werner Herzog, Peter Doig and Stan Douglas. In forming the 'modern' perception of the world, Nicholas Temple considers Friedrich Hölderlin's understanding of topography as the decisive link to a 'mythical past and a transient present'. ' I reflect on Hölderlin's perspective of the world through the notion of 'divine absence' and Heidegger's interpretation of that understanding on the nature of being. Documentation of my practice consists of colour image video stills and text from 2003-2008. CONCLUSION I consider some of the core ideas explored and developed during the doctorate programme and suggest future projects. Temple, N. (2007) Disclosing Horizons: Architecture, perspective and redemptive space. Oxon: Routledge, p. 5.
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Carlbaum, Oskar, and Michael Novén. "Real-Time Magnetohydrodynamic Space Weather Visualization." Thesis, Linköpings universitet, Medie- och Informationsteknik, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-141686.
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This work describes the design and implementation of space weather related phenomena within the interactive astro-visualization software OpenSpace. Data sets from the Community Coordinated Modelling Center (CCMC) at the National Aeronautics and Space Administration (NASA) were used to implement time-varying high-resolution solar imagery from space observatory spacecraft and time-varying field lines from the different models produced at the CCMC. The obtained results were used to take an audience on an interactive journey through the solar system, at the worlds first ever live planetarium show about space weather.
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Scott, Susan M. "New approaches to space-time singularities /." Title page, contents and abstract only, 1991. http://web4.library.adelaide.edu.au/theses/09PH/09phs429.pdf.
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Huang, Li-Ke. "Space-time DS-CDMA communication systems." Thesis, Imperial College London, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.397681.
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Youngman, Ben. "Space-time modelling of extreme values." Thesis, University of Sheffield, 2011. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.555232.
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The motivation for the work in this thesis is the study of models for extreme values that have clear practical benefit. Specific emphasis is placed on the modelling of extremes of environmental phenomena, which often exhibit spatial or temporal dependence, or both, or are forced by external factors. The peaks-over-threshold approach to modelling extremes combats temporal dependence, providing a way in which likelihood-based methods may he used reliably. The method is widely used and has sound asymptotic foundations. However its performance in practical situations is less well understand. The essence of the method is to identify clusters of extremes and estimate the required extremal properties based only on the cluster peaks. A simulation study is used here to assess the performance of the method. This study shows that while not robust to some of its arbitrary choices, such as cluster identification procedure, if clusters are identified using Ferro and Segers' (2003) automatic procedure then the peaks-over-threshold method typically gives accurate estimates of extremal properties. It is often common for extreme values to be affected by external factors. For example environmental extremes may be expected to behave differently at different times of the year. Incorporating beliefs about external factors was recognised early on in the development of extremal models as an important consideration, and a simple way in which this can be achieved is by allowing parameters of extremal distributions to depend on covariates. The work here considers whether choosing logical covariate forms for variation in parameters leads to improved estimation of extremal properties. It is found that a degree of improved accuracy in estimates can be achieved upon choice of a suitable model. but that the uncertainty in estimates, which is important to report, is poorly quantified.
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Santiago-GermaÌn, Wenceslao. "Space-time structure and hidden dimensions." Thesis, University of Newcastle Upon Tyne, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.289215.
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Wilson, Daniel. "Local time-space calculus with applications." Thesis, University of Manchester, 2018. https://www.research.manchester.ac.uk/portal/en/theses/local-timespace-calculus-with-applications(f04e32e3-4c9b-4348-a7f3-803dee125e43).html.
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Fitriani. "Multiscale Dynamic Time and Space Warping." Thesis, Massachusetts Institute of Technology, 2008. http://hdl.handle.net/1721.1/45279.
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Thesis (S.M.)--Massachusetts Institute of Technology, Computation for Design and Optimization Program, 2008.Includes bibliographical references (p. 149-151).
Dynamic Time and Space Warping (DTSW) is a technique used in video matching applications to find the optimal alignment between two videos. Because DTSW requires O(N4) time and space complexity, it is only suitable for short and coarse resolution videos. In this thesis, we introduce Multiscale DTSW: a modification of DTSW that has linear time and space complexity (O(N)) with good accuracy. The first step in Multiscale DTSW is to apply the DTSW algorithm to coarse resolution input videos. In the next step, Multiscale DTSW projects the solution from coarse resolution to finer resolution. A solution for finer resolution can be found effectively by refining the projected solution. Multiscale DTSW then repeatedly projects a solution from the current resolution to finer resolution and refines it until the desired resolution is reached. I have explored the linear time and space complexity (O(N)) of Multiscale DTSW both theoretically and empirically. I also have shown that Multiscale DTSW achieves almost the same accuracy as DTSW. Because of its efficiency in computational cost, Multiscale DTSW is suitable for video detection and video classification applications. We have developed a Multiscale-DTSW-based video classification framework that achieves the same accuracy as a DTSW-based video classification framework with greater than 50 percent reduction in the execution time. We have also developed a video detection application that is based on Dynamic Space Warping (DSW) and Multiscale DTSW methods and is able to detect a query video inside a target video in a short time.
by Fitriani.
S.M.