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Dissertations / Theses on the topic 'Spatial links'
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Spence, Charles J. "Audiovisual links in attention." Thesis, University of Cambridge, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.264512.
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Pennington, Sandra Lynn. "Automatic geometric modeling of spatial mechanism links." Thesis, Virginia Polytechnic Institute and State University, 1986. http://hdl.handle.net/10919/91056.
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This thesis introduces GENMOD, a collection of subroutines which allow automatic geometric modeling of 3-D models for spatial links or linkages given a minimum amount of information as input. The subroutines utilize the CADCD (CADAM, Inc.) geometry interface software to enter 3-D data directly into the CAD/CAM database. Wire-frame and surface models are produced. Input is accepted from user created files with a standardized format allowing the GENMOD subroutines to be implemented regardless of the synthesis and analysis routines used. The realistic visualization of a mechanism during the synthesis and analysis process can help the mechanism designer to eliminate unacceptable linkage configurations in the early design stages thereby saving time and money. A complete description of the subroutines is provided in addition to sample graphic output.M.S.
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Kennett, Steffan Anthony. "Links in spatial attention between touch and vision." Thesis, Birkbeck (University of London), 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.343623.
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Newman, Lisa J. "MYB misexpression links the spatial control of lignification with photomorphogenesis." Thesis, University of Oxford, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.365719.
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Szabo, Melinda Dora. "Adaptive gain spatial receiver for wide dynamic range communication links." Thesis, Massachusetts Institute of Technology, 2020. https://hdl.handle.net/1721.1/130198.
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Thesis: M. Eng., Massachusetts Institute of Technology, Department of Electrical Engineering and Computer Science, May, 2020Cataloged from student-submitted PDF of thesis.
Includes bibliographical references (pages 317-323).
Wireless optical communication facilitates high-speed transmission across long distances. However, time-varying and spatially-dependent attenuation through freespace channels due to scattering impedes operation for many wide dynamic range links. In the atmosphere, communication is often limited to short transmission times when optimal power is delivered to the detector, as the distance and channel conditions between ground terminals and airborne or space systems changes constantly. This effect is even more apparent in oceans, where optical attenuation varies so drastically that it has hindered practical implementation of high-speed communication undersea. To accommodate the wide range of input powers, a novel adaptive gain spatial receiver is developed in this thesis. The designed device replaces multiple detector functions of an existing underwater laser communication system with an adjustable gain and sensitivity receiver for long-range or high-rate transmissions. The novel receiver also provides spatial resolution for improved efficiency and performance. In preliminary laboratory tests, a proof-of-concept setup validates simulation expectations and informs future terminal integration. Using the new system, a wide range of input power across six orders of magnitude down to single photon detection and data rates up to 1Gb/s are attainable, which will enable future tests in the open ocean.
by Melinda Dora Szabo.
M. Eng.
M.Eng. Massachusetts Institute of Technology, Department of Electrical Engineering and Computer Science
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Li, Xuan. "Planning for Spatial Analysis of Links between Parkinson Disease and Pesticide Exposure." University of Toledo / OhioLINK, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=toledo1310051225.
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Wardle, Perry. "Economic and social linkages in a spatial cluster of traditional small manufacturing firms." Thesis, University of Sheffield, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.324453.
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Read, Jessica Sian. "Development of methodology for identifying spatial links between environmental exposure and disease prevalence." Thesis, Cardiff University, 2007. http://orca.cf.ac.uk/54602/.
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The recent increased availability of geographically linked individual level health outcome data and improvements in exposure mapping techniques, which furnish point exposure estimates, motivate the development of spatial statistical methodology that takes full advantage of individual level data. Kernel density estimation is a powerful tool for mapping the risk of a health outcome that uses individual level data. Development of kernel density methodology has provided a global significance test for regions of elevated relative risk and a test for the spatial association between a health outcome and environmental exposure. Comparisons with some existing spatial statistical techniques highlight the strengths of the kernel density based methods. Moreover, simulation exercises indicate that the kernel density test for spatial association is a more powerful testing procedure than the most popular standard test proposed by Stone. Kernel density estimation and the global significance test for regions of elevated relative risk are illustrated for congenital malformations around a landfill site and sex ratios in Cardiff and the Vale of Glamorgan. The application of these methodologies revealed that both birth outcomes had a statistically significant heterogeneous spatial pattern over the relevant study regions even after adjustment for known confounders. Good quality, high resolution environmental exposure data was unavailable and prevented a direct application of the kernel density test for spatial association with a health outcome. However, the test can be applied to any two relative risk/density surfaces and was used to compare the spatial patterns of chromosomal and non-chromosomal anomalies in the region of the Nant y Gwyddon landfill site. It was concluded that the spatial patterns for the two sets of anomalies were different. The test was also used to assess the quality of the adjustment for confounders when producing expected risk surfaces and the adjustment was found to be adequate.
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Begg, Tracey. "Spatial and temporal dynamics in the development of invading cynipid communities in Britain." Thesis, University of Edinburgh, 2008. http://hdl.handle.net/1842/3992.
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The British Isles have been invaded by 12 alien cynipid gallwasps over the past 150 years. The first 4 of these species have been studied in depth and represent a model system in phytophagous insect community structure. In this thesis, I extend this research programme to incorporate 8 further invaders. I examine recent changes in the distribution of invading oak gallwasps in Britain and spatial patterns in the composition of the associated communities of phytophagous cynipid inquilines and parasitoids. I use fully quantitative webs to assess the diversity and strength of trophic interactions between native and invading species and assess the potential for apparent competition between gallwasps mediated by shared natural enemies. Of the first 4 invaders to be studied, 3 have expanded their range since 1991/2. Three of these 4 species are now well established in Scotland, while Andricus corruptrix remains confined to England. Four new invaders (A. aries, A. lucidus, A. grossulariae, Aphelonyx cerricola) are established in southern England and are spreading. Rates of range expansion vary across species (between means of 3.3 and 24.4 km per year), and may be correlated with variation in lifecycles and abundance. The four newest invaders (Neuroterus saliens, Plagiotrochus australis, P. coriaceus, P. quercusilicis) are currently restricted to their sites of first record. Previous studies on one of the early invaders, Andricus quercuscalicis, identified south to north and east to west declines in community species richness and in the abundance of specific parasitoid species. I find that: 1) Parasitoid associations with the asexual galls of A. quercuscalicis track inquiline recruitment to this host. 2) The longitudinal and latitudinal gradients in parasitoid species richness demonstrated in previous work are no longer apparent, suggesting that younger northern communities may be converging on their older southern counterparts. 3) Inquilines show increasing survivorship with distance from the original centre of their distribution in south east England, suggesting at least temporary exploitation of enemy-free space. 4) The recently invading Andricus and Aphelonyx species have all rapidly recruited parasitoids and inquilines. Fully quantitative webs were constructed for 4 sites in England and Scotland incorporating both native and invading cynipids. I tested the hypothesis that newly arriving gallwasp generations would fall within food web compartments based on their host oaks and location on the tree as demonstrated in previous work. Counter to this hypothesis, parasitoids attacking one of the newest invaders (A. grossulariae) break down host tree-associated compartmentalisation. Where A. grossulariae has yet to become established, host-based compartmentalisation remains pronounced. Despite extensive sharing of parasitoid species, I found only one strong indirect interaction between species (both aliens) and no evidence for widespread apparent competition. Spatial density dependent predation on an appropriate scale can stabilise population dynamics. I quantified predation by blue tits (Parus caeruleus) of spring generation bud galls on Turkey oak (Q. cerris) at three spatial scales (shoots within branches, branches within trees, trees within sites). I found significant levels of bird predation, with most variation occurring between trees rather than between shoots within branches. Spatial density dependence was detected at sites in southern England, primarily at the level of trees within a site. Relationships at finer spatial scales were far more variable in magnitude and sign. My results suggest that blue tits forage primarily at the level of trees. This thesis presents comprehensive new data on the establishment and spread of 12 invading cynipid species and on their interactions with native communities. The results further understanding of both spatial and temporal aspects of natural enemy recruitment to invading species. In particular, it is clear that individual invading species can significantly modify trophic linkage between established food web compartments. Finally, my data emphasise the significant (but often unstudied) contribution of highly mobile vertebrate predators to otherwise closed ecological microcosms.
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Hedberg, Nils. "Sea cages, seaweeds and seascapes : Causes and consequences of spatial links between aquaculture and ecosystems." Doctoral thesis, Stockholms universitet, Institutionen för ekologi, miljö och botanik, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-141009.
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Aquaculture is of growing importance in the global seafood production. The environmental impact of aquaculture will largely depend on the type of environment in which the aquaculture system is placed. Sometimes, due to the abiotic or biotic conditions of the seascape, certain aquaculture systems tend to be placed within or near specific ecosystems, a phenomenon that in this thesis is referred to as aquaculture system - ecosystem links. The exposed ecosystems can be more or less sensitive to the system specific impacts. Some links are known to be widespread and especially hazardous for the subjected ecosystem such as the one between the shrimp aquaculture and the mangrove forest ecosystem. The aim of this thesis was to identify and investigate causes and consequences of other spatial links between aquaculture and ecosystems in the tropical seascape. Two different aquaculture system - ecosystem links were identified by using high resolution satellite maps and coastal habitat maps; the link between sea cage aquaculture and coral reefs, and the one between seaweed farms and seagrass beds. This was followed by interviews with the sea cage- and seaweed farmers to find the drivers behind the farm site selection. Many seaweed farmers actively choose to establish their farms on sea grass beds but sea cage farmers did not consider coral reefs when choosing location for their farms. The investigated environmental consequences of the spatial link between sea cage aquaculture and coral reefs were considerable both on the local coral reef structure, and coral associated bacterial community. Furthermore, coral reef associated fish are used as seedlings and feed on the farms, which likely alter the coral food web and lower the ecosystem resilience. Unregulated use of last resort antibiotics in both fish- and lobster farms were also found to be a wide spread practice within the sea cage aquaculture system, suggesting a high risk for development of antibiotic resistant bacteria. The effects of seaweed farms on seagrass beds were not studied in this thesis but have earlier been shown to be rather substantial within the borders of the farm but less so outside the farm. Further, a nomenclature is presented to facilitate the discussion about production system - ecosystem links, which may also be used to be able to incorporate the landscape level within eco-certifying schemes or environmental risk assessments. Finally - increased awareness of the mechanisms that link specific aquaculture to specific habitats, would improve management practices and increase sustainability of an important and still growing food producing sector - the marine aquaculture.At the time of the doctoral defense, the following papers were unpublished and had a status as follows: Paper 2: Manuscript. Paper 3: Manuscript. Paper 4: Manuscript.
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Ness, Lindsay Anne. "Solute deposition to an upland catchment : spatial patterns, temporal trends and links to stream water chemistry." Thesis, University of East Anglia, 2006. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.429683.
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Knoedler, Alexander A. (Alexander Andrew). "Reciprocity-enhanced time-division multiplexed optical switching with spatial diversity for free-space optical communication links." Thesis, Massachusetts Institute of Technology, 2019. https://hdl.handle.net/1721.1/122706.
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Thesis: S.M., Massachusetts Institute of Technology, Department of Aeronautics and Astronautics, 2019Cataloged from PDF version of thesis.
Includes bibliographical references (pages 105-108).
This thesis investigates a performance analysis and experimental measurements of a free-space optical communications system that exploits optical reciprocity to switch between multiple (N) spatially-diverse apertures to increase data transmission through a scintillating channel. Electromagnetic signals, specifically optical, propagating along either direction of the same path experience the same changes in signal strength (reciprocity). A duplex link on a fading channel can use knowledge of the channel condition to decide to switch between multiple spatially diverse apertures, functionally improving the quality of the link. This concept will be referred to as "time division multiplexed (TDM) reciprocity." Higher throughput, higher received power, and lower latency can be achieved by exploiting reciprocity to choose a higher quality channel. The experimental work in this thesis includes systems measurements and assessment of components and sub-systems that enable TDM reciprocity.
This thesis outlines system requirements and trades for the N-aperture switching system. Important engineering decisions are discussed: sizing N, clock recovery, real-time atmosphere assessment, and direct versus coherent detection. The efficacy of increasing data rate with TDM reciprocity is verified by conducting an experimental BER (bit error rate) measurement campaign on a physical DPSK (differential phase shift keying) modem. The BER experiment uses scintillation data to simulate the atmosphere. The thesis concludes with results of testing of the optical switch and and a description of the driving logic for the optical switch. This switch architecture was designed with the capability to be integrated with a variable-rate, burst-mode, DPSK modem that can achieve data rates from 72 Mbps to 2.880 Gbps.
The switch is fast (<200 ns) to reduce impact on higher data rates produced by the modem, and needs to handle high power to reduce the need for multiple fiber amplifiers in the transmitter. An initial synchronization test of the switch with signal generators indicates switching without impacting error rate is possible within the DPSK modulation dead time. Aggregate gain includes a higher average received power, better receiver performance, and fixed switch insertion loss. For a link with a error-free-communication BER threshold of 1% and a scintillation index of 0.28, total gain is estimated to be 1.7 dB for N 4 and 2.7 dB for N = 10 apertures. For a link with a error-free-communication BER threshold of 1% and a scintillation index of 1.0, total gain is estimated to be 5.1 dB for N = 4 and 6.5 dB for N = 10 apertures.
Future work on the reciprocity concept could incorporate a fast switch into a dedicated fiber or free space optical experiment, rather than as an addition to an engineering modem. Future experiments should also investigate the potential of other mechanisms (e.g. high speed buffering or variable channel rates) to use knowledge of a fading channel.
United States. Air ForceContract No. FA8702- 15-D-0001
by Alexander A. Knoedler.
S.M.
S.M. Massachusetts Institute of Technology, Department of Aeronautics and Astronautics
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Peramaki, Liisa. "Spatial distribution of lead in soil and sediment in Iqaluit, Northwest Territories and links with human health." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp04/mq24387.pdf.
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Stephen, Linda J. "Vulnerability and food insecurity in Ethiopia : forging the links between global policies, national strategies and local socio-spatial analyses." Thesis, University of Oxford, 2003. http://ora.ox.ac.uk/objects/uuid:8802ce2e-5e77-4263-b6d6-6a10802732c9.
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Ethiopia is a food insecure country in the Horn of Africa. A wide body of literature in the 1980s and early 1990s justifiably associated food insecurity and famine in Africa and Ethiopia with centralised governance and weaknesses in national early warning systems, which were argued to have had an enduring influence on the outcomes of early warning and famine/food security interventions. Among this wide body of research, however, little attention has been devoted to the socio-spatial dimensions of the problem and the resulting effect on interventions aimed at addressing vulnerability to food insecurity at the household level. In this thesis it is argued that social processes, inherent in the structure of societies and institutions, combine globally, nationally and locally to undermine the treatment of vulnerability to food insecurity as a variable, place-based phenomenon. The arguments are developed with reference to food policy and vulnerability assessments in Ethiopia during the 1990s. Specific references are made to the findings from interviews with national early warning system staffs carried out in 1997 and 1998 and to food security surveys in Delanta Dawint, Ethiopia carried out in 1998.
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Poh, Seng Cheong Telly. "Simulations of diversity techniques for urban UAV data links." Thesis, Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 2004. http://library.nps.navy.mil/uhtbin/hyperion/04Dec%5FPoh.pdf.
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Hamann, Maike. "Mapping social-ecological systems and human well-being : A spatial exploration of the links between people and the environment in South Africa." Licentiate thesis, Stockholms universitet, Stockholm Resilience Centre, 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-102860.
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It has become increasingly clear that dealing with present day environmental crises requires a holistic view that takes into account the interactions of social and ecological factors across multiple spatial and temporal scales. An example of where this new paradigm is being operationalized is the study of social-ecological systems. A substantial aspect of this growing research area aims to contribute to a more comprehensive understanding of the links between social-ecological systems, the ecosystem services they generate, and human well-being. This thesis summarizes the first part of a PhD project with the overall objective of unravelling some of these linkages using a mapping approach in South Africa, a country with high levels of social and ecological diversity. In the first paper, I present an approach to mapping social-ecological systems based on different bundles of ecosystem services. Mapping social-ecological systems has so far mainly been achieved by the overlay of separate social and ecological data. Here, I identify characteristic bundles of ecosystem services and use these bundle types as a proxy for different social-ecological systems in South Africa. The emergent pattern shows three distinct and spatially coherent systems that represent an overall low, medium and high level of ecosystem service use amongst households, and differs markedly from maps based on the overlay of social and ecological datasets. This approach not only identifies areas within South Africa where people are especially vulnerable to environmental changes that negatively affect ecosystem services, but also highlights areas in which distinctly different system dynamics operate in close proximity. It is especially in those areas where systems characterized by high and low dependence on ecosystem services lie side by side that nuanced and differentiated decision-making is required to sustainably manage ecosystem services in support of human well-being across all sectors of society. In the second paper I expand on the approach pioneered in Paper I by mapping human well-being bundles in South Africa. Mapping human well-being as bundles allows us to interrogate the trade-offs between different constituents of well-being at the sub-national scale, something that is not possible when measuring human well-being based on indicators or indices that reduce well-being to a single number. This approach also enables us to perform a spatial comparison between the levels of ecosystem service use (identified in Paper I) and human well-being, which signifies an important step forward in the development of quantitative tools for the analysis of the relationship between ecosystem services and human well-being at scales between the local and the national.Governance of ecosystem services under scenarios of change in southern and eastern Africa
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Cremer-Schulte, Dominik Clemens. "On the links between natural amenities, residential processes and urban planning : lessons from an Alpine urban region." Thesis, Université Grenoble Alpes (ComUE), 2016. http://www.theses.fr/2016GREAE002/document.
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Les régions urbaines alpines et en proximité des Alpes présentent des caractéristiques spécifiques: elles combinent une ressource foncière limitée pour l'urbanisation et une qualité environnementale particulière dans l'arrière-pays. Cette combinaison les rend particulièrement propices à la péri-urbanisation, et potentiellement à la ségrégation sociale. Dans le contexte d'une métropolisation croissante, ces deux processus entravent des objectifs centraux de la planification urbaine, à savoir la compacité des formes urbaines, la mixité fonctionnelle, l'égalité territoriale et la cohésion sociale. Dans les régions urbaines alpines, les liens entre l'environnement montagnard, les politiques de planification et les processus résidentiels à l’œuvre restent toutefois peu connus.Cette thèse analyse la planification urbaine et des choix de localisation résidentielle en région urbaine alpine. Elle cherche à comprendre les liens entre l'environnement montagnard, les politiques de planification urbaine et deux processus résidentiels: la péri-urbanisation et la ségrégation sociale. Son objectif général est de mettre en lumière comment et dans quelle mesure ces processus résidentiels sont influencés par (i) l'environnement montagnard et (ii) les politiques de planification pour ainsi fournir des recommandations pour la planification territoriale en région urbaine. Pour cela, nous nous appuyons sur trois contributions distinctes en utilisant la région urbaine de Grenoble comme zone d'étude centrale.La première contribution porte sur les changements dans la pratique de la planification urbaine contemporaine dans la région d'étude. Basée sur une recherche qualitative, elle se concentre sur l'émergence d'une planification territoriale stratégique et sa montée en échelle vers des périmètres de planification plus larges intégrants les espaces péri-urbains. Le chapitre montre la création de nouvelles arènes de gouvernance qui remettent en question les cultures de planification locale.La deuxième contribution analyse les liens entre les préférences pour l'environnement naturel, les choix de localisation résidentielle et la ségrégation sociale. En utilisant des modèles de choix de localisation pour la région d'étude et la région métropolitaine de Marseille, cette partie présente une analyse de ségrégation contrefactuelle qui compare les résultats de ségrégation og avec fg{} et og sans fg{} les préférences pour l'environnement naturel entre les deux régions. Le principal résultat est que la recherche des milieux naturels par les ménages a des effets significatifs sur la ségrégation sociale. Cette recherche a le plus souvent tendance à renforcer la ségrégation, mais peut également être un facteur d'atténuation.La dernière contribution étudie les liens entre les politiques de planification urbaine et les processus résidentiels. Le chapitre développe un modèle de choix discrets pour créer et analyser des simulations de demande résidentielle pour différents scénarios de politique de planification. Les résultats illustrent que les scénarios tendanciels de planification soutiennent et potentiellement renforcent la périurbanisation dans la région d'étude. Des politiques de planification plus contraignantes semblent capables de freiner et potentiellement d'inverser la dispersion de la demande. Les politiques visant à ré-centraliser la demande tendent à maintenir, voire accroître les niveaux de ségrégation sociale.Les résultats de cette thèse suggèrent l'importance d'une prise en compte plus grande de l'environnement naturel dans la planification urbaine et territoriale. Si les disparités spatiales dans la qualité environnementale contribuent aux processus résidentiels qui portent atteintes aux objectifs du développement urbain, les politiques de planification devraient rendre compte de ces disparités afin de limiter l'étalement urbain, la ségrégation sociale et l'inégalité environnementale, non seulement dans un contexte de région urbaine alpineUrban regions in and close to the Alps have specific characteristics: they combine a limited land resource for urban development with particular environmental quality in their mountainous hinterland. This combination makes them particularly prone to peri-urbanisation, and potentially social segregation. In the context of continued metropolisation, both of these processes work against central objectives of urban planning, notably compactness of settlement patterns, functional mix, social equity and cohesion. In Alpine urban regions, the links between the mountain environment, urban planning policies and residential processes remain, however, not well understood.This thesis analyses urban planning and residential moves in an Alpine urban region. It seeks to understand the links between the mountain environment, urban planning and notably two residential processes: peri-urbanisation and social segregation. Its general objective is to investigate how and to what extent these residential processes are influenced by (i) the mountain environment and (ii) urban planning policies and to develop recommendations for urban and regional planning. The thesis does this via three distinct contributions which use the urban region of Grenoble in the French Alps as a central study area.The first contribution addresses changes in contemporary urban planning practice in the study region. Based on qualitative research, it focuses on the shift towards strategic spatial planning and on territorial re-scaling towards large urban-peri-urban planning perimeters. The chapter shows the creation of new governance arenas which call into question local planning cultures.The second contribution investigates the links between preferences for the natural environment, residential moves and social segregation. Using location choice models for the study region and the Marseille metropolitan area, this chapter presents a counterfactual segregation analysis that compares segregation outcomes ``with'' and ``without'' preferences for the natural environment. The main result is that households' search for natural environments has significant impacts on social segregation. It most often contributes to reinforcing segregation, but can also be an attenuating factor.The last contribution investigates the links between urban planning policies and residential processes. The chapter develops a residential location choice model in order to predict and analyse residential demand patterns for different planning policy scenarios in terms of concentration and segregation. The scenario results show that continued trends in urban planning policies would sustain and potentially reinforce peri-urbanisation in the region. Confining planning policies are found to be capable of curbing and potentially reversing demand dispersion. Policies that aim at re-centralising demand sustain and potentially increase social segregation levels.The results of this thesis call for a stronger integration of the natural environment in urban and regional planning. If spatial disparities in environmental qualities contribute to residential processes that are detrimental to compact urban forms and an equitable access to environmental quality, then planning should incorporate and account for these disparities in order to prevent further loss of land resources, socio-spatial fragmentation and environmental inequality, not only in an Alpine urban region context
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Kim, Muriel. "The controls of sedimentary links on the spatial distribution of Atlantic salmon («Salmo salar») juveniles and spawning activity along rivers in the Gaspé Peninsula, Canada." Thesis, McGill University, 2009. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=40685.
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The longitudinal trend in the size of a river’s bed material is best represented as being composed of several discrete units, called sedimentary links, in which each sedimentary link is initiated by a source of coarse sediment, and the bed material becomes progressively finer in the downstream direction. In this study, the concept of sedimentary links is applied to salmon rivers in the Gaspé Peninsula of Quebec, Canada, which have previously not been studied in the context of sedimentary links. Also, the relationship between the sedimentary links and the distributions of Atlantic salmon (Salmo salar) juveniles and spawning activity along these rivers is tested.A key finding in this study is that the sedimentary links of the Gaspé rivers are subdivided into not only source zones (experiencing a spatially continuous supply of coarse sediment) and fining segments (where the sediment becomes progressively finer downstream), but also an additional component not identified in earlier studies, which we call intermediate zones, in which the channel experiences regular but spatially discontinuous supplies of coarse sediment, producing “disturbed downstream fining”.Using data on salmon juvenile and redd densities provided by local wildlife managers, it was found that greater net gains in older juvenile densities generally occur in source zones and intermediate zones, rather than in the finer-sediment sections of fining segments. There is also a strong, positive correlation (R2 = 0.91, p = 0.001) between a river’s overall density of juveniles and the proportion of the river length that is occupied by either source zones or intermediate zones. Spawning activity is generally the highest in fining segments and intermediate zones, and lowest in source zones. There is also a significant, negative correlation (R2 = 0.87, p = 0.001) between the size of a river’s salmon run and the distance separating the river mouth from the nearest boulder-rich intermediate zone or source zone; we speculate that the proximity of such a zone to the river mouth influences the survival rates of juveniles during the winter immediately preceding their seaward migration.La variation longitudinale de la grosseur de substrat le long des rivières est mieux représentée comme étant composée d’une séries de liens sédimentaires, où chaque lien est initié par une source de substrat grossier, suivi par un affinement du substrat dans la direction avale avant d’atteindre la source de substrat grossier suivant. Dans ce projet de recherche, le concept des liens sédimentaires est appliqué pour une groupe de rivières dans la Gaspésie (Québec, Canada), dont jusqu’à date n’ont jamais été le sujet d’une étude des liens sédimentaires. De plus, la relation entre les liens sédimentaires et la distribution des juvéniles et des frayères de saumons atlantiques le long de ces rivières est testée.Nous avons découvert que les liens sédimentaires des rivières gaspésiennes sont divisés en trois types de segments : les zones sources (où du substrat grossier est introduit dans le canal), les zones d’affinement (où le substrat devient de plus en plus fin dans la direction avale) et les zones intermédiaires (un nouveau type de zone qui n’a jamais été identifié dans les études précédentes, où le canal ne subit que des apports ponctuels mais discontinus répétés de sédiments grossiers, et dont l’affinement du substrat est obscurci).En utilisant des données historiques sur les densités de juvéniles et des frayères dans les rivières gaspésiennes, nous avons découvert que des gains de juvéniles plus âgés sont concentrés surtout dans les zones sources et les zones intermédiaires. Il existe aussi une forte corrélation positive (R2 = 0.91, p = 0.001) entre la densité moyenne de juvéniles dans une rivière et la proportion de la longueur de cette rivière occupée par des zones sources ou des zones intermédiaires. Les densités de frayères sont supérieures dans les zones d’affinement et les zones intermédiaires, tandis qu’elles sont plus faibles dans les zones sources. Il existe aussi une forte corrélation négative (R2 = 0.87, p = 0.001) entre la grosseur de la montaison de saumon et la distance qui sépare l’embouchure de la rivière et la zone intermédiaire/source la plus rapprochée. Nous croyons que la proximité d’une telle zone de l’embouchure de la rivière influence les taux de survie des juvéniles pendant l’hiver précédant leur migration vers la mer
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Van, der Velde Lode. "Missing links in the genesis of type 1 diabetes : A geographical approach to the case of enteroviruses in the Nordic region." Thesis, Stockholms universitet, Kulturgeografiska institutionen, 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-157064.
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Type 1 diabetes (T1D) is an autoimmune disease that destroys the bodies’ insulin producing beta-cells. The disease is understood to be triggered in genetically susceptible individuals by environmental factors. While the genetic side of the etiological model has to some degree been uncovered, there is no clear understanding of which environmental factors play a role in the disease process. Several hypotheses claim to explain the development of T1D, of which enteroviral infections show the most promise. According to this hypothesis high prevalence of enteroviral infections would also mean high incidence rates of T1D. This study focused on four Nordic countries (Denmark, Finland, Norway and Sweden) that as late as 2017 were found in the top 10 countries for incidence rate of childhood-onset T1D in the world. Incidence rates of T1D and prevalence of enteroviruses were mapped and geographically analyzed according to the principles of spatial epidemiology, after which correlation coefficients were calculated. In doing so the study tried to answer to which extent the prevalence of enteroviruses could explain the regional variations in T1D. For all countries no significant correlation was found, but increasing sample size, by grouping countries, showed considerably different outcomes with a small positive correlation in the case of Norway and Finland.
20
La, Marca Anna. "Crossing Lines : A study about lines and their translations." Thesis, Konstfack, Inredningsarkitektur & Möbeldesign, 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:konstfack:diva-7860.
Full textAbstract:
Lines are everywhere and as humans we produce lines all the time. In this project I used the line as a method, a metaphor, and a material to explore what are the elements that influence and condition the way we move and behave around different spaces. Lines can be read as many things and for this project I choose to work with lines that could be understood as boundaries and limits. How do we deal with lines in our everyday life? How do lines and bodies influence each other? How is the space choreographed and experienced according to the boundaries that exist in it? However not all boundaries are made of matter. In fact, some of them are invisible and manifest as prohibitions, regulations, prejudice, or just cultural norms. These limits can also be understood as non-matter lines that have an impact on one's experiences. Through several explorations, the project proposes an installation that seeks to embody the spatial boundaries that cannot always be seen. Using light and sound as catalyzers for these experiences, the installation is a reflection on what happens when we meet those invisible lines, how they have the power to change our usual path and to make us move differently around a space.
21
Dahhan, Ryzlène. "Prendre place dans la ville : immigré-e-s nord-africain-e-s dans les marchés périphériques de Nice." Thesis, Université Côte d'Azur (ComUE), 2017. http://www.theses.fr/2017AZUR2011.
Full textAbstract:
A la croisée de la sociologie des relations interethniques et des minorités et de la sociologie urbaine, cette thèse étudie dans leurs dimensions sociales et spatiales les recompositions, expansions et contractions des frontières entre groupes placés en situation minoritaire. Elle s’appuie sur les résultats d’une enquête qualitative, ethnographique et comparative menée au sein de trois marchés de la périphérie de Nice où se concentrent des individus minorisés et marginalisés. D’une part, elle analyse les rapports sociaux qui se jouent dans le fonctionnement et l’appropriation de ces espaces urbains marchands par des acteurs en situation minoritaire. Elle montre quels sont les effets concrets de telles appropriations sur le partage de l’espace, leurs relations, mais aussi les liens entre eux et leur environnement. D’autre part, elle décrit les formes d’expression publique des identités telles qu’elles se donnent à voir dans les interactions marchandes et non marchandes en cherchant à comprendre comment ces espaces de commerce orientent la façon dont les relations interethniques s’organisent dans la coprésence. En mettant en évidence l’intersection des différentes formes de domination en actes au sein de ces espaces, la thèse montre ainsi les variations de l’expérience minoritaireCombining the sociological study of interethnic relations and minorities and urban sociology, this thesis focuses on the reconfigurations, expansions and contractions of the boundaries between groups placed in a minority situation. This thesis draws on the results of qualitative, ethnographic and comparative investigation carried out in three marketplaces located on the outskirts of Nice where these minority groups and marginalized people are concentrated. First, this thesis studies the social relations at stakes in the functioning and appropriation of these marketplaces by minority groups. It allows to understand how this appropriation appears in the sharing of space, their relation and the links between them and their environment. Secondly, the thesis describes the various forms identities are expressed during market and non-market interactions, trying to understand how these commercial spaces orientate the way interethnic relations are organized in co-presence. By highlighting the intersection of the different forms of domination in action within these spaces, the thesis thus explores the multiplicity of minority experience
22
Allen, April Diane. "Complex Spatial Skills: The Link Between Visualization and Creativity." Thesis, Virginia Tech, 2000. http://hdl.handle.net/10919/31494.
Full textAbstract:
The purpose of this study was to determine if there is a correlation between spatial skills and creativity in interior design students.
Participants were subjects who took a visualization assessment and created the 33 projects used in the study, and 11 judges, professional design experts who rated the projects. The sample of subjects was comprised of interior design students at a FIDER-accredited institution in southwest Virginia. The judges included interior design educators and interior design graduate students having previous practice experience.
Subjects completed a pencil-and-paper Visualization Assessment consisting of 36 questions using two-dimensional and three-dimensional drawings (Isham, 1997). A percentage score for spatial skills was calculated for each subject based on the number of correct answers.
Design projects created by the students were assessed by subjective ratings on three Dimensions of Judgment taken from the Consensual Technique for Creativity Assessment (Barnard, 1992; Amabile, 1982). The three dimensions used in this study included Appropriateness, Creativity, and Novelty. Ratings were collected in two judging sessions at a local site.
Interjudge reliabilities exceeded the established criterion level (.70 or greater) on all three dimensions, with coefficients ranging from .729 to .866. Interjudge reliability for the Creativity dimension was .866, indicating a high level of agreement among judges on creativity.
Intercorrelations among the dimensions indicated a high degree of association between the variables with Appropriateness and Novelty both significantly correlated with the Creativity dimension.
Pearson product-moment correlation was used to determine if there was a significant correlation between visualization and creativity in interior design students. No significant correlation was found.Master of Science
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Nicolas, Judith. "On the link between saccadic adaptation and visuospatial attention." Thesis, Lyon, 2019. http://www.theses.fr/2019LYSE1024/document.
Full textAbstract:
L’attention et l’Adaptation Saccadique (AS) sont des composants essentiels de la perception visuelle, le premier renforce le traitement sensoriel des items sélectionnés, le second maintient la précision des mouvements des yeux vers ceux-ci. Ils partagent aussi une dichotomie : les saccades volontaires et l’orientation endogène de l’attention suivent nos buts internes tandis que les saccades réactives et l’orientation exogène répondent aux changements soudains dans l’espace visuel. Leurs substrats neuronaux se superposent en partie. Enfin, chacun impacte l’autre au niveau comportemental. Ce travail de doctorat étudie l’hypothèse d’un couplage fonctionnel entre attention et AS.Toutes nos études chez l’humain sain reposent sur la mesure des performances attentionnelles avant et après l’exposition à l’AS (ou contrôle). Dans la première nous avons exploré les bases neurophysiologiques du couplage réactif/exogène en magnétoencéphalographie. Dans la suivante nous avons comparé l’orientation exogène mesurée par un paradigme de Posner avant et après AS réactive. La dernière, basée sur le même modèle, explorait la modalité volontaire/endogène. Nos résultats montrent que l’AS augmente l’activité oscillatoire gamma et renforce l’orientation de l’attention spatiale. Nous proposons que le couplage repose sur la co-activation de populations neuronales par la plasticité oculomotrice et l’attention au niveau du Cortex Pariétal Postérieur (CPP). Cette activation émerge initialement d’un double effet du cervelet qui inhibe le CPP gauche et active le CPP droit. Cet effet augmente la dominance hémisphérique droite et le biais attentionnel vers la gauche. Notre travail ouvre des perspectives de rééducation des déficits visuo-attentionelsAttention and Saccadic Adaptation (SA) are critical components of visual perception, the former enhancing sensory processing of selected objects, the latter maintaining the eye movements accuracy towards them. Also, a similar dichotomy could be applied to both: voluntary saccades and endogenous attentional shifts follow internal goals while reactive saccades and exogenous shifts are elicited by sudden changes in the environment. Further, their neural substrates partially overlap and they impact each other behaviorally. This PhD work investigates the hypothesis of a functional coupling linking attention and SA in healthy humans. Our experimental contributions all rely on the measurement of attentional performances before and after an exposure to SA (or control). In the first study, we recorded brain magnetic fields to investigate neurophysiological bases of the reactive/exogenous coupling. In the second study, we compared exogenous orienting measured in a Posner-like paradigm before and after reactive SA. Finally, using the same design, the third experiment investigated the voluntary/endogenous modality. We found that SA increased gamma band activity and boosted the orienting of spatial attention. We thus propose that this functional coupling relies on neuronal populations co-activated by both oculomotor plasticity and attention in the Posterior Parietal Cortex (PPC). The initial activation would emerge from a dual effect of the cerebellum inhibiting the left PPC and activating the right PPC. This effect would increase the right hemispheric dominance and the leftward attentional bias. This work opens new perspectives for the rehabilitation of visuoattentional deficits
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Near, William G. "Spatial tracker for an air-to-ground laser communication link." Thesis, Massachusetts Institute of Technology, 2012. http://hdl.handle.net/1721.1/77033.
Full textAbstract:
Thesis (M. Eng.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2012.Cataloged from PDF version of thesis.
Includes bibliographical references (p. 93-94).
In this thesis, I designed several of the hardware components of a spatial tracker for an air-to-ground laser communication system; these include a PWM switching amplifier and the control systems for driving the primary steering and tracking elements required in the acquisition and maintenance of an optical communication link. The hardware was designed for low size, weight, and power (SWaP), low cost, and easy system integration. A performance analysis is presented comparing the designed hardware to a benchmark lasercom system developed at MIT Lincoln Laboratory.
by William G. Near.
M.Eng.
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Butler, David Buchanan. "Spatial scales of geomagnetically induced currents in B.C. Hydro's power transmission system." Thesis, University of British Columbia, 1990. http://hdl.handle.net/2429/28926.
Full textAbstract:
Geomagnetically Induced Currents (GIC's) in B. C. Hydro's 500 kV transmission
system have in the past been responsible for the generation of harmonics of 60 Hz, system voltage drops, and misoperation of relay units. Characterization of the associated magnetic storms' spatial scales would further the understanding of GIC generation in the area, and allow advanced warning of potential problems in future power transmission projects.
Data collected in 1984 at four substations were analysed to determine lateral variations in geomagnetically induced earth surface electric fields. Inversion techniques were employed to find a variety of solutions that would reproduce the data.
Results suggested that the magnetic storms were larger than the area monitored,
and that resultant electric fields seen by a large portion of the transmission grid were uniform. Departures from this uniformity in other portions of the electric
field models were felt either to be due to earth induction effects, or in some cases, to be artifacts of the data analysis techniques.
An experiment designed to determine the controlling factors behind GIC's is outlined. Considerable effort would be required to explicitly determine all electric fields affecting the transmission systemScience, Faculty of
Earth, Ocean and Atmospheric Sciences, Department of
Graduate
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Hunter, Sally E. "Spatial and temporal variation in contourite sedimentation : link to variations in palaeocirculation." Thesis, University of Southampton, 2008. https://eprints.soton.ac.uk/145875/.
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Brittell, Megen. "Improving Accessibility of Spatial Information: A Technique Using Parametrized Audio to Symbolize Lines." Thesis, University of Oregon, 2011. http://hdl.handle.net/1794/12168.
Full textAbstract:
xi, 79 p. ： ill. (some col.)Graphics provide a rich display medium that facilitates identification of spatial patterns but are inaccessible to people who are blind or low vision. Audio provides an alternative medium through which to display information. Prior research has explored audio display of lines representing functions and location of screen objects within a graphical user interface; however, presentation of spatial attributes of lines (angle, number of segments, etc.) of geographic data has received limited attention. This thesis explores a theoretical foundation for designing audio displays and presents an experimental evaluation of line symbology. Sighted users who were blindfolded and blind users performed a line following task and a matching task to evaluate the line symbology. Observed differences between the conditions did not reach statistical significance. User preferences and observed strategies are discussed.
Committee in charge: Dr. Michal Young， Chair
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Ozturk, Tunay. "Finding The Optimum Route For Transmission Lines Within Gis." Master's thesis, METU, 2007. http://etd.lib.metu.edu.tr/upload/2/12608356/index.pdf.
Full textAbstract:
This study defines the optimum route planning for Electric Transmission Lines by
Multicriteria Decision Analysis which is based on Geographic Information Systems (GIS).
Determination of the optimum route is performed by using both the spatial and Euclidean
distances between two points located on the Earth&rsquos surface. The criteria needed to be taken into account to define the route of the Electrical Transmission Lines were evaluated with help of the experts who are doing this business in the available system and for this study the decision about the usage of needed data such as landuse map, landuse capability map, geology map, road map, zone plan and digital elevation models is also made with their knowledge. A Matlab code, which computes the optimum distance between two transformers by using real distance (spatial distance) method and by considering materials mentioned above is written. The results are compared with the ones found from the Euclidian distance, which is the common distance finding method in the available commercial GIS softwares. The spatial resolution effect in finding the spatial distance is also analyzed. The routes obtained by two different distance computation methods are compared with the existing route. The economical expectations in finding the optimum route are also discussed.
29
JUAJINOY, JOSE LUIS CALPA. "DECOUPLED SIGNAL DETECTION IN THE UP-LINK OF MU-MIMO SYSTEMS WITH SPATIAL MODULATION." PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO, 2017. http://www.maxwell.vrac.puc-rio.br/Busca_etds.php?strSecao=resultado&nrSeq=30930@1.
Full textAbstract:
PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIROCOORDENAÇÃO DE APERFEIÇOAMENTO DO PESSOAL DE ENSINO SUPERIOR
PROGRAMA DE EXCELENCIA ACADEMICA
Este trabalho de dissertação de mestrado apresenta os resultados obtidos com a conjunção de duas técnicas propostas para utilização em modernos sistemas de comunicações: a Modulação Espacial (Spatial Modulation - SM) e a detecção desacoplada de sinais. Na primeira parte são abordados os fundamentos teóricos da detecção de sinais com modulação espacial, uma comparação entre os sistemas MIMO (Multiple Input Multiple Output) tradicionais e os sistemas SM-MIMO, uma revisão bibliográfica sobre trabalhos previamente feitos no tema e os diferentes tipos de detectores que podem ser empregados em sistemas com modulação espacial. A seguir são abordadas diferentes técnicas para desacoplamento de sinais, as quais permitem a separação na estação radio-base dos sinais oriundos de diferentes tipos de usuários, visando simplificar e adequar o procedimento de detecção às necessidades do usuário da rede. Finalmente uma análise de desempenho, em termos da taxa de erro de bit, e complexidade computacional, em termos do número médio de flops requerido por vetor de símbolos detectado, é realizada para as diferentes associações de técnicas de desacoplamento e detectores SM enfocados neste trabalho.
This work dissertation presents the results obtained from the conjunction of two proposal techniques for the use in modern systems of communications: the Spatial Modulation and the Decoupling Signal Detection. In the first part are discussed the theorical bases of the signal detection with Spatial Modulation, a comparison between the traditional MIMO systems and the SM-MIMO systems, a bibliographical review about previousworks in the topic and the different kinds of detectors that can be used in systems with Spatial Modulation. Then the different techniques of signal decoupling are discussed, which allow the separation in the radio base station of the signals coming from the different classes of users, to simplify and adapt the process of detection and the requirements of the user in the network. Finally a performance analysis in terms of the bit error rate and computational complexity in terms of average number of flops required fot the vector of symbols detected, is done for the studied detectors in the dissertation, using the same different techniques of decoupling studied in this work.
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Neo, Poh Ling. "Increasing the transmission capacities of a multimode fibre transmission link using a spatial light modulator." Thesis, University of Cambridge, 2008. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.612421.
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Byrne, Catherine Margaret McCombe. "Spatial stochastic models of HSV-2 lesion dynamics and their link with HIV-1 acquisition." Thesis, University of British Columbia, 2016. http://hdl.handle.net/2429/58436.
Full textAbstract:
Patients with Herpes Simplex Virus-2 (HSV-2) infection face a significantly higher risk of contracting HIV-1. This marked increase is thought to be due not only to herpetic lesions serving as an entry point for the HIV-1 virus, but also to the increase in CD4+ T cells in the human genital mucosa during HSV-2 lesional events. By creating a stochastic, spatial, mathematical model describing the behaviour of the HSV-2 infection and immune response in the genital mucosa, I first capture the dynamics that occur during the development of an HSV-2 lesion. I then use this model to quantify the risk of acquiring HIV-1 in HSV-2 positive patients upon sexual exposure, and determine whether antivirals meant to control HSV-2 can decrease HIV-1 infectivity. While theory predicts that HSV-2 treatment should lower HIV-1 infection probability, my results show that this may not be the case unless a critical dosage of HSV-2 treatment is given to the patient. These results help to explain the conflicting data on HIV-1 infection probability in HSV-2 patients and allow for further insight into the type of treatment HSV-2 positive patients should receive to prevent HIV-1 infection.Science, Faculty of
Mathematics, Department of
Graduate
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Abrahamse, Clarie Janet. "Integration between dividing lines : the spatial and social integration of African immigrants in post-apartheid Cape Town." Thesis, Massachusetts Institute of Technology, 2009. http://hdl.handle.net/1721.1/49724.
Full textAbstract:
Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Architecture, 2009.Includes bibliographical references (p. 154-164).
Over the last fifteen years since the demise of apartheid South Africa, under a new democratic dispensation, has become host to several million immigrants from the rest of the continent. This has been paralleled by a rise in violent acts of xenophobia against an increasingly diverse immigrant population by those who consider themselves "legitimate citizens" of the new post-apartheid nation. As with immigration worldwide, this is a particularly urban phenomenon. Yet in contrast to the urban theories on immigration which have developed in parallel with the emergence of the industrial city, specifically in the Chicago School writings of the 1920s, the South African city has a very particular cultural, historical and physical geography, deeply embedded with notions of race and belonging, and heavily influencing the perception of its new immigrants. The question thus arises as to whether the international urban theories have any explanatory purchase in the South African case. Through analysing Cape Town according to these theories and examining the historical urban-planning responses to immigration and the "other" that have been employed since the colonial era, a few sites are identified in contemporary Cape Town in which a certain level of integration is occurring between immigrant communities and their host societies. It is argued that these sites show strong urban commonalities in terms of the formal and social environments they are able to provide. One of these urban neighbourhoods, Mowbray, is examined in detail against a series of hypotheses drawn from the international theories and the metropolitan and historical understanding of the city.
(cont.) These relate to the specific aspects of urban space, grain of fabric and land markets present, the specific ideologies that have guided the making of the neighbourhood, and the effects of civic institutions and organisations in aiding the building of place-based social networks. The analysis of how each of these aspects play out across the spatial and social landscape of the neighbourhood then informs the building of an urban theory and response to the spatial promoters of environments of integration in the city, recognising that while immigration is a very complex phenomenon, its urban location represents an opportunity for urbanism to be brought to bear on making the experience of immigrants less hostile.
by Claire Janet Abrahamse.
S.M.
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Lins, Jonas [Verfasser], Gregor [Gutachter] Schöner, and Sen [Gutachter] Cheng. "An embodied account of spatial language grounding / Jonas Lins ; Gutachter: Gregor Schöner, Sen Cheng ; Fakultät für Psychologie." Bochum : Ruhr-Universität Bochum, 2018. http://d-nb.info/117152160X/34.
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Marseille, M. "Observations et modélisations de proto-étoiles massives dans le cadre de l'observatoire spatial Herschel." Phd thesis, Université Sciences et Technologies - Bordeaux I, 2008. http://tel.archives-ouvertes.fr/tel-00375600.
Full textAbstract:
La formation des étoiles massives reste, à ce jour, encore mal connue à cause de l'extrême quantité d'énergie que ces étoiles dégagent, limitant en conséquence leurs masses théoriques et contredisant les observations de ce type d'étoile. Les observatoires du futur (en particulier l'observatoire spatial Herschel) vont tenter de répondre à cette problématique grâce notamment aux émissions moléculaires de l'eau. L'analyse précise et correcte de ces données, dans l'avenir, nécessite donc dès aujourd'hui un travail associant des observations et des modélisations des objets concernés. C'est dans ce but que cette thèse a consisté en l'élaboration d'une méthode de modélisation dite « globale » d'objets proto-stellaires massifs (proto-amas ou cœurs denses massifs). Celle-ci a permis une description physique et une étude chimique des multiples cœurs denses massifs étudiées, et a ouvert de nombreuses voies vers des aspects évolutifs. Elle a également donné des indices pour affiner le programme d'observation en temps garanti WISH des raies moléculaires de l'eau et confirmé le rôle clef de cette molécule pour la compréhension de la formation des étoiles massives.
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Shin, Sangyoung. "Spatial dimensions of workplaces and the effects on commuting: the dase of metropolitan Dallas-Fort Worth." Texas A&M University, 2002. http://hdl.handle.net/1969.1/540.
Full textAbstract:
There has been a lively debate over using land use strategies to reduce automobile dependence over the past decade. As a part of the issue, this study investigates the spatial characteristics around workplaces and their relationships to commuting made by the employees in metropolitan Dallas-Fort Worth. The tools of geographic information systems (GIS) are utilized to measure workplace environs. Several statistical methods are applied to analyze commuting behavior.
This study finds that low-density suburban workplaces are associated with shorter vehicle travel times but more drive-alone trips. While major suburban centers attain some level of compact development in terms of local activity mix and regional accessibility, employees in these centers are far more automobile dependent than employees in older centers in the central city. In the suburban locations, workplaces in residence-based centers and master planned communities with a mix of activities are associated with less drive-alone commuting and more carpooling. Workers take advantage of the abundance of activities, as larger and denser centers are associated with more non-work activity stops after work. Yet, the trip chaining is overwhelmingly driven by automobile use.
This study also finds that spatial factors are significant in explaining commuting behavior. Yet, the importance of spatial factors varies with the aspect of travel. Spatial factors do a better job in explaining travel times than in explaining travel mode and trip chaining. The way a particular spatial factor affects commuting also varies with the aspect of travel. For instance, land use intensity factors are associated with longer travel times but less drive-alone trips. While this study suggests that concerted planning may affect travel, some socioeconomic variables, including income and automobile ownership, are strongly related to more automobile travel.
The findings suggest that the land use strategies to cope with transportation and air quality problems, such as new urbanism and jobs-housing balance, would be a viable option in and around employment locations. But, such strategies should be carefully designed because of the differences in effectiveness of spatial factors with travel outcomes and the trade-offs between travel outcomes with a particular spatial factor.
36
Lee, Katherine, and katielee mail@gmail com. "Embodying the Built World: Drawing Boundaries, Walking Lines." RMIT University. Art, 2009. http://adt.lib.rmit.edu.au/adt/public/adt-VIT20091015.141915.
Full textAbstract:
Intro In this practice-led research project I investigate relations between structures of coercion in the built world and sculptural language. The aim of my project is to present a series of exhibitions and situations that examine architectures of bodily discipline as practices of form/space composition and spatial manipulation. Such architectures range from the delineation of public space to the choreography of bodies by urban design. The project engages the viewer in a dialogue around art and the spatio-visual codes that embody what Michel Foucault regarded as the coercive powers of modern 'carceral culture'. I research a range of studio and workshop, site and gallery based processes contextualised by contemporary notions of sculpture, materiality and art practice. I work from a position derived from the writings on art by the minimalist sculptor Robert Morris (1966, 1970), Rosalind Krauss (1977, 1979) and Hal Foster (1996), which stress the experience of the viewer as an integral part of the art work and emphasise the nature of art work in 'real' spaces. Proposed Project To investigate relations between 'structures of coercion' in the built world and sculptural language through a series of exhibitions and situations (installations at ARIs, public collaborative works, studio documentations) that examine architectures of bodily discipline as practices of form/space composition and spatial manipulation. The proposed artworks will engage the viewer in a dialogue around art and the spatio-visual codes that exist in urban space. Main objective The main objective of this research project is to: Identify new ways of understanding spatio-visual codes of discipline in the city through sculpture practice.
37
Tran, Van Canh [Verfasser], and Michael [Akademischer Betreuer] Gertz. "Learning Social Links and Communities from Interaction, Topical, and Spatio-Temporal Information / Canh Tran Van ; Betreuer: Michael Gertz." Heidelberg : Universitätsbibliothek Heidelberg, 2014. http://d-nb.info/1180032055/34.
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Chun, Yongwan. "Behavioral specifications of network autocorrelation in migration modeling an analysis of migration flows by spatial filtering /." Columbus, Ohio : Ohio State University, 2007. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=osu1187188476.
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Nguyen, Tan Hung [Verfasser], Hans Joachim [Akademischer Betreuer] Linke, Ngoc Hieu [Akademischer Betreuer] Nguyen, Boris [Akademischer Betreuer] Lehmann, Carl-Alexander [Akademischer Betreuer] Graubner, and Martin [Akademischer Betreuer] Wagner. "Spatial Planning in Flood-prone Areas / Tan Hung Nguyen ; Hans Joachim Linke, Ngoc Hieu Nguyen, Boris Lehmann, Carl-Alexander Graubner, Martin Wagner." Darmstadt : Universitäts- und Landesbibliothek Darmstadt, 2019. http://d-nb.info/120108654X/34.
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Nguyen, Tan Hung [Verfasser], Hans Joachim Akademischer Betreuer] Linke, Ngoc Hieu [Akademischer Betreuer] Nguyen, Boris [Akademischer Betreuer] Lehmann, Carl-Alexander [Akademischer Betreuer] Graubner, and Martin [Akademischer Betreuer] [Wagner. "Spatial Planning in Flood-prone Areas / Tan Hung Nguyen ; Hans Joachim Linke, Ngoc Hieu Nguyen, Boris Lehmann, Carl-Alexander Graubner, Martin Wagner." Darmstadt : Universitäts- und Landesbibliothek Darmstadt, 2019. http://d-nb.info/120108654X/34.
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Nguyen, Tan Hung [Verfasser], Hans-Joachim [Akademischer Betreuer] Linke, Ngoc Hieu Akademischer Betreuer] Nguyen, Boris [Akademischer Betreuer] [Lehmann, Carl-Alexander [Akademischer Betreuer] Graubner, and Martin [Akademischer Betreuer] Wagner. "Spatial Planning in Flood-prone Areas / Tan Hung Nguyen ; Hans Joachim Linke, Ngoc Hieu Nguyen, Boris Lehmann, Carl-Alexander Graubner, Martin Wagner." Darmstadt : Universitäts- und Landesbibliothek Darmstadt, 2019. http://nbn-resolving.de/urn:nbn:de:tuda-tuprints-92661.
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Polles, Fiorella Lucia. "Properties of the interstellar medium of the star-forming galaxy, IC10, at various spatial scales." Thesis, Université Paris-Saclay (ComUE), 2017. http://www.theses.fr/2017SACLS276/document.
Full textAbstract:
Les propriétés du milieu interstellaire (MIS) influencent fortement l’environnement et les processus menant à la formation d’étoiles qui, à son tour, dicte l’évolution d’une galaxie. Les galaxies naines du Groupe Local sont de parfaits laboratoires pour comprendre comment le contenu en métaux (ou métallicité) du MIS affecte l’interaction entre le gaz, la poussière et les étoiles. Mon travail de thèse porte sur les propriétés physiques des régions HII et du gaz diffus ionisé de la galaxie naine IC10, de métallicité 1/3 solaire. La proximité de cette galaxie (d=700kpc) permet l’analyse du MIS à différentes échelles spatiales: des nuages brillants compacts (25pc) au corps entier de la galaxie formant des étoiles (650pc). Afin de mesurer les propriétés physiques du MIS, j’ai modélisé les raies d’émission en infrarouge observées avec Spitzer et Herschel grâce à des modèles de photoionisation et de photodissociation. Je présente une exploration complète de plusieurs méthodes pour déterminer, de manière la plus fiable et selon les contraintes disponibles, les propriétés du MIS à diverses échelles. J’ai contraint les propriétés des nuages compacts les plus brillants dans IC10 et montré que l’émission à plus grande échelle (300pc) est dominée par celle de ces nuages. Enfin, je démontre le besoin d’un modèle à plusieurs composantes pour reproduire les observations dans leur ensembleThe properties of the Interstellar Medium (ISM) strongly influence the environment and processes that lead to star-formation, which in turn, drives the evolution of a galaxy. Dwarf galaxies in the Local Group are perfect laboratories to investigate how the metal-poor ISM affects the interplay between gas, dust and stars. In this thesis, I investigate the properties of the HII regions and the diffuse ionized gas of the nearby dwarf galaxy IC10, which has a metallicity of 1/3 solar. Its proximity (d=700 kpc) enables the analysis on different spatial scales: from the compact clumps (~25 pc) to the whole star-forming body of the galaxy (~650pc). In order to measure the physical properties of the ISM, I model the infrared emission lines observed with Spitzer and Herschel with photoionization and photodissociation models. I present an extensive exploration of different methods to determine the most reliable ISM properties, based on the available constraints. I determined the properties of the brightest star-forming clumps within the galaxy and show that the emission at large scales (~300 pc) is dominated by that of the compact, bright clumps that lie within the region. I further demonstrate the need for a multi-component model to fully reproduce the observations
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Moussa, Ahmad. "Pour une cohérence du résultat d'un opérateur dans un contexte spatial, temporel et alphanumérique." Thesis, Normandie, 2018. http://www.theses.fr/2018NORMIR31/document.
Full textAbstract:
L'information géographique peut être perçue selon trois dimensions : une dimension spatiale (e.g., ville), une dimension temporelle (e.g., date) et une dimension alphanumérique (e.g., population). L'intégration de ces différents types de données est l'un des challenges actuels de la production d'applications permettant la représentation et le traitement d'informations géographiques. Nous nous proposons de contribuer à cette problématique en proposant une méthode afin d'aider à la gestion de la cohérence des données impliquant deux des trois dimensions. Cette cohérence peut se poser après application d'un opérateur sur les informations géographiques. La méthode que nous proposons est basée sur des liens sémantiques entre les dimensions. Une liaison sémantique représente le rapport logique entre les dimensions. Cette liaison associée à des règles de comportement des opérateurs de manipulation, nous permet de garantir la cohérence du modèle de données associé au résultat d’un opérateurGeographic information can be perceived according to three dimensions: a spatial dimension (e.g., city), a temporal dimension (e.g., date) and an alphanumeric dimension (e.g., population). The integration of these various types of data is one of the current challenges in order to model geographic representation and to process geographic information. We contribute to this challenge by proposing a method to help in the management of data coherency involving two on three dimensions. This coherency can be settled after applying an operator on geographic information. Our method is based on semantic links between dimensions. A semantic link represents the logical interaction between (two) dimensions. This connection, associated with a set of rules depending on data manipulation operators, allows us to guarantee the coherency of the data model associated with the result of an operator
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Mungara, Ratheesh Kumar. "System-level performance of interference-aware spatial frequency reuse." Doctoral thesis, Universitat Pompeu Fabra, 2016. http://hdl.handle.net/10803/400869.
Full textAbstract:
Spatial frequency reuse is a long-established approach for enhancing the capacity of wireless systems through increased spectral efficiency (bits per second per unit bandwidth). The future 5th generation of wireless systems is expected to incorporate various forms of frequency reuse. This includes multiple-input multiple-output (MIMO) communication enabling frequency reuse across antennas, device-to-device (D2D)-based densification allowing spectrum reuse across direct communication links, and full duplexing utilizing the same spectrum for communication in the transmit and receive directions.
This dissertation aims at determining the performance limits of emerging wireless systems underpinned by dense spatial frequency reuse and interference suppression, and to glean key system design insights. Stochastic geometry is the toolbox invoked to conduct the analysis, with network locations modeled as points of a Poisson process. A new framework is developed by introducing a Gaussian fit to the interference and variable degrees of spatial averaging, which enable more meaningful results and compact expressions compared to those of existing analyses.
Within this framework, we first consider MIMO spatial multiplexing and interference alignment (IA). The former scheme utilizes all available spatial dimensions for signaling and the latter minimizes interference at the expense of knowing the instantaneous fading states at both transmitters and receivers and of a reduction in spatial signaling dimensions. Despite the intense work on IA and spatial multiplexing, there is limited work aimed at understanding their engineering tradeoff in the context of practically relevant cellular settings such as propagation losses, fading dynamics due to user mobility and imperfect knowledge of the fading states. We have studied this problem in depth through both system- and link-level analyses. Even under perfect knowledge of the fading, IA is seen to be beneficial over spatial multiplexing only in very specific and relatively infrequent network situations, and IA loses all its advantages at vehicular speeds when the fading knowledge is imperfect.
Second, we focus on ITLinQ and FlashLinQ, the two principal channelization schemes proposed to date for controlling the interference in D2D networks. An analytical characterization of ITLinQ scheme is provided, opening the door to optimizing its controllable parameters. It is shown that both channelization schemes outperform the unchannelized baseline, with a slight edge for ITLinQ. On the most unfavorable network geometries, ITLinQ yields multiple-fold improvements in spectral efficiency with respect to an unchannelized network.
Finally, we introduce full-duplex transceivers in cellular networks and characterize the impact of increased interference on their performance. It is established through analysis and complemented by simulations on a Vodafone LTE field test network that additional user-to-user interference only has a minor impact while base-to-base interference would render full-duplex operation unfeasible in dense microcellular networks without any interference management.
In summary, MIMO spatial multiplexing and D2D-based densification are seen to play a vital role in improving wireless system capacity while IA and full duplexing are found to be ineffective.La reutilització de la freqüència espacial és l’aproximació més acceptada per tal de millorar la capacitat dels sistemes wireless mitjançant l'increment de l'eficiència espectral (bits per segon per unitat d'ample de banda). S'espera que la futura cinquena generació de sistemes wireless incorpori diverses formes de reutilització de freqüència. Això inclou la comunicació multi-input multi-output (MIMO) que permet la reutilització a través d'antenes, densificació dispositiu-a-dispositiu (D2D) que permet reutilitzar l'espectre a través d’enllaços de comunicació directa, així com un full-dúplex emprant el mateix espectre per a la comunicació en la transmissió i recepció de direccions. Aquest treball pretén determinar els límits de rendiment dels sistemes wireless emergents, basats en una densa reutilització de la freqüència espacial i en la supressió d'interferències, així com espigolar coneixement clau per al disseny de sistemes d'aquest tipus. La geometria estocàstica és l'eina que s'aplicarà a l'anàlisi que es durà a terme, modelitzant les localitzacions dins la xarxa com a punts d'un procés de Poisson. La introducció d'un ajust Gaussià a la interferència, conjuntament amb la consideració de nivells variables d'expectació espacial, han permès definir un nou marc matemàtic que fa possible unes expressions més compactes i uns resultats més significatius en comparació amb els anàlisis existents. Dins d'aquest marc, en primer lloc es prenen en consideració la multiplexació MIMO i l'aliniament d'interferència (IA, en les seves sigles en anglès). El primer esquema empra totes les dimensions espacials disponibles per a la senyalització i el segon minimitza la interferència a costa de conèixer els estats de esvaïment instantani dels transmissors i receptors, i d'una reducció en les dimensions de senyalització espacial. Malgrat l'intens treball en l'IA i la multiplexació espacial, s'ha prestat escassa atenció a tractar de comprendre el seu balanç d’enginyeria en el context d'xarxes cel.lulars de rellevància pràctica, com els de propagació de pèrdues, o les dinàmiques de esvaïment degudes a la mobilitat de l'usuari i al coneixement imperfecte dels estats de esvaïment. En aquest treball s'ha estudiat en profunditat aquest problema a través d'anàlisis tant a nivell dels enllaços com del sistema. Fins i tot en condicions de coneixement perfecte del esvaïment, l'IA resulta beneficiós sobre la multiplexació només en situacions de xarxa molt específiques i relativament infreqüents, mentre que perd tots els seus avantatges a velocitats vehiculars quan el coneixement del esvaïment és imperfecte. En segon lloc, el treball es centra en el ITLinQ i el FlashLinQ, els dos principals esquemes de canalització proposats fins al moment per controlar la interferència en xarxes D2D. S'ofereix una caracterització analítica de l'esquema ITLinQ, obrint així la porta a l'optimització dels seus paràmetres controlables. Es mostra que tots dos esquemes de canalització aconsegueixen millors resultats que l'esquema no canalitzat, amb un lleuger avantatge per al ITLinQ. Considerant la geometria de xarxa més desfavorable, el ITLinQ produeix millores múltiples en l'eficiència espectral en comparació amb la xarxa no canalitzada. Finalment, el treball introdueix els transreceptors full-dúplex en xarxes cel.lulars i caracteritza l'impacte de la interferència incrementada en el seu funcionament. A través d'anàlisis i de simulacions complementàries en una xarxa de test de Vodafone LTE, s'estableix que la interferència d'usuari a usuari té un impacte poc significatiu mentre que la interferència de base a base faria inviable l'operació full-dúplex en xarxes microcell.lulars sense gestió de les interferències. En resum, aquest tesis doctoral aporta evidència de que el multiplexat MIMO i la densificació basada en D2D juguen un paper vital en la millora de la capacitat dels sistemes wireless mentre que el IA i el full-dúplex resulten inefectius.
45
Richard, Edouard. "Étude et réalisation d’un nouveau système de référence spatio-temporel basé sur des liens inter-satellites dans une constellation GNSS." Thesis, Paris 6, 2016. http://www.theses.fr/2016PA066545/document.
Full textAbstract:
L'exactitude délivrée par les systèmes de positionnement globaux par satellites (GNSS) est un facteur clé pour de nombreuses applications scientifiques telles que le positionnement de points géodésiques ou d’autres satellites, l'établissement de systèmes de référence spatio-temporels, la synchronisation d’horloges ou encore l'étude directe du lien pour sonder l’atmosphère. L'augmentation de la constellation GNSS avec des mesures de pseudo-distances entre les satellites est une option prometteuse pour améliorer l'exactitude du système. Plusieurs études présentent l'apport qualitatif de ces liens inter-satellites (ISL), mais ne permettent pas de mesurer efficacement l'impact quantitatif de cette technologie. Dans cette thèse, nous avons effectué une étude différentielle entre un système classique (possédant seulement des liens standards espace-sol) et un système augmenté avec des ISL. Les deux systèmes sont étudiés sous les mêmes hypothèses et à travers le même code de calcul. Celui-ci est composé de deux parties distinctes et autonomes : une simulation d’observables sous la forme de pseudo-temps de vol bruités, et une analyse qui délivre, après ajustement des paramètres, les bilans d’erreurs quantitatifs. La comparaison des bilans d'erreurs quantitatifs associés aux deux systèmes nous permet d’établir, pour une même application donnée, les différences de performance relatives entre les deux systèmes. Les résultats obtenus permettent de franchir un pas de plus vers la validation de l’apport des liens inter-satellites et sont à considérer pour les versions futures des systèmes de navigation par satellitesThe accuracy reached by the Global Navigation Satellite Systems (GNSS) is critically important for many scientific applications such as geodetic point or satellite positioning, space-time reference frame realization, clocks synchronization or the study of the links to probe the atmosphere. One option for improving the system accuracy is the use of inter-satellite pseudo-range measurements, so called inter-satellite links (ISL). Several studies have shown the qualitative interest of ISL but do not allow to efficiently measure the quantitative impact of this new technology on space-time positioning. In this thesis, we present a differential study between a standard system (with standard satellite-to-ground links only) and system augmented by ISL. The two systems are compared under the same hypothesis and simulated within the same software. The software is made of two distinct and independent parts : the simulation which generates the noisy pseudo-ranges, and an analysis which uses a non linear adjustment procedure in order to recover the initial parameters of the simulation and compute the quantitative error budgets. For a given application, the quantitative comparison between the error budgets of both systems allow us to highlight the relative merits of the two configurations. Our results are a further step in the characterization of the interest of ISL and should prove useful for the design of future satellite navigation system design
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Olarte, Bacares Carlos Augusto. "Four essays about the link between improvements of urban transports and criminality in big cities : the case of Bogota." Thesis, Paris 1, 2014. http://www.theses.fr/2014PA010003/document.
Full textAbstract:
Cette thèse cherche à d'étudier et à déterminer l'impact des améliorations des transports publics sur la configuration de la criminalité dans une grande ville comme Bogota. Dans une première étape, cette recherche cherche à préciser le nombre d'emplois joignables par les habitants de la ville dans trois différents intervalles de temps. La taille effective du marché du travail est donc définir dans le but de déterminer si les habitants des différentes zones qui composent la ville ont le même,èegré d'accessibilité aux emplois. Une fois définie l'accessibilité, cette étude fait une étude comparative par rapport aux caractéristiques socio-économiques des habitants par zone ainsi que par rapport à la présence ou le manque d'améliorations du système de transport dans chaque zone qui composent la ville de Bogota. La présence des améliorations du système de transport est définie par le passage du système de transport appelé Transmilenio (TM) dans chaque zone. Dans le but d'approfondir sur le lien qui existe entre les caractéristiques socio-économiques des habitants et la présence de TM dans chaque zone de la ville, nous nous concentrons, dans une deuxième étape, sur l'existence d'une possible relation endogène de la présence de TM dans la concentration des emplois et des hauts revenus à Bogota. L'objectif de cette analyse est de déterminer si les améliorations des transports publics ont une relation causale dans la localisation des emplois et des hauts revenus dans chaque zone de la ville. Nous adoptons ensuite l'hypothèse que les criminels préfèrent commettre leurs crimes dans les bassins d'emplois et dans les zones à forte concentration des hauts revenus (indépendamment de la localisation des zones résidentielles). Dans le même ordre d'idée et afin d'établir une relation causal sur l'évolution de cinq différents types de crime dans chaque zone de la ville, cette étude réalise une analyse ex-ante et ex-post la mise en place de Transmilenio. En raison de la faiblesse de la base de donné pour les différentes périodes, les résultats de cette étape ne sont pas homogènes et ce qui les rend peu convaincants. Cependant, ils nous donnent une approximation pertinente de l'impact que Transmilenio peut avoir dans la configuration de la criminalité dans la ville. Ces résultats nous mènent à faire, dans une dernière étape, une analyse de causalité pour la période pour laquelle les données disponibles sont complets pour toutes les zones de la ville et ne montrent pas des problèmes de fiabilité. Après cette étape d'analyse, les résultats sont convaincants. Ils suggèrent qu'il existe bien une relation causale de la présence de Transmilenio sur l'évolution de trois des cinq types de crimes sujets de notre étude. Les résultats permettent également d'identifier une claire dépendance spatiale de la concentration des crimes dans la ville. Il semble donc que, malgré les multiples effets positifs que l'amélioration des transports publics peut avoir pour les habitants d'une ville, ceci peut aussi stimuler une hausse de certains types de crimes dans les zones desservies par Transmilenio. Malgré les limites de cette étude qui devront être résolues dans des futures recherches, les résultats obtenus, ainsi que la façon dont le sujet est abordé, représentent une perspective d'analyse innovatrice pour une meilleure compréhension des éventuelles conséquences négatives qui peuvent contrecarrer les objectifs des politiques des transports urbains dans les grandes villes. Nous pensons que cette thèse contribue à la complémentarité des études sur les effets des transports urbainsThe aim of this PhD dissertation is to study and reveal the impact of public transports' improvements on the configuration of the crime on a big city like Bogota. First, this research focuses on a calculation of the number of reachable jobs of bogotanians. The effective size of labor market is computed in order to establish if inhabitants have the same degree of accessibility to jobs with respect to their socio-economic situation and with respect to the presence of enhancements of public transports in zones where they live. The presence of improvements of public transports is defined by the presence of Transmilenio system in each zone of the city. Following the same intuition, this research also study, in a second time, the possible endogeneity of the presence of Transmilenio (TM) on the concentration of jobs and on the income of inhabitants of each zone. More precisely, the aim of this analysis is to determine if improvements of public transports may have a causal relation on the localization of jobs and the concentration of highest incomes in the city. The objective of this investigation is to establish that high incomes, jobs centers may be localized, in a big proportion, because of the presence of TM. Following the hypothesis suggested on several studies regarding the fact that criminals prefer to commit their crimes in zones with high density of jobs and in zones with highest incomes (regardless housing zones or job centers), this dissertation follow, in a thirdly, with an ex-ante and ex-post study of the evolution of cNme with respect to the opening of Transmilenio in each zone. The goal ofthis analysis is to establish a causal relation of enhancements of public transports on the evolution of five different types of crimes in each zone. Because of the weakness of available data, results are unfortunately not conclusive but give us an appropriate approximation of the impact that Transmilenio system may have on crime configuration. These results lead to make, on a final instance, a causal analysis for the year on which we have whole data. Results are conclusive: a causal relationship of Transmilenio on three of five types of crime object of this study is confirmed. ln addition, a spatial dependence on the concentration of crimes is also confirmed. It appears that, regardless the positive impacts that it could have, the presence of Transmilenio and hence, the enhancements of public transports in different zones of Bogota make raise sorne kinds of crimes. Even if this research presents sorne limitations that should be solved on future studies, the way how the issue is analyzed provides new perspectives for the comprehension of sorne negative consequences that can thwart positive objectives of urban transport policies. We believe that this PhD dissertation contributes to complement the studies about the effect of urban transports
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Alaca, Aygul Filiz. "Natural Language Query Processing In Ontology Based Multimedia Databases." Master's thesis, METU, 2010. http://etd.lib.metu.edu.tr/upload/12611816/index.pdf.
Full textAbstract:
In this thesis a natural language query interface is developed for semantic and spatio-temporal
querying of MPEG-7 based domain ontologies. The underlying ontology is created by attaching
domain ontologies to the core Rhizomik MPEG-7 ontology. The user can pose concept,
complex concept (objects connected with an &ldquoAND&rdquo
or &ldquo
OR&rdquo
connector), spatial (left, right . . . ), temporal (before, after, at least 10 minutes before, 5 minutes after . . . ), object trajectory and directional trajectory (east, west, southeast . . . , left, right, upwards . . . ) queries to the system. Furthermore, the system handles the negative meaning in the user input. When the user enters a natural language (NL) input, it is parsed with the link parser. According to query type, the objects, attributes, spatial relation, temporal relation, trajectory relation, time filter and time information are extracted from the parser output by using predefined rules. After the information extraction, SPARQL queries are generated, and executed against the ontology by using an RDF API. Results are retrieved and they are used to calculate spatial, temporal, and trajectory relations between objects. The results satisfying the required relations are displayed in a tabular format and user can navigate through the multimedia content.
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Sánchez, Garache Marvin. "Multihop Wireless Networks with Advanced Antenna Systems : An Alternative for Rural Communication." Doctoral thesis, KTH, Kommunikationssystem, CoS, 2008. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-4755.
Full textAbstract:
Providing access to telecommunication services in rural areas is of paramount importance for the development of any country. Since the cost is the main inhibiting factor, any technical solution for access in sparsely populated rural areas has to be reliable, efficient, and deployable at low-cost. This thesis studies the utilization of Multihop Wireless Networks (MWN) as an appealing alternative for rural communication. MWN are designed with a self-configuring capability and can adapt to the addition or removal of network radio units (nodes). This makes them simple to install, allowing unskilled users to set up the network quickly. To increase the performance and cost-efficiency, this thesis focuses on the use of Advanced Antenna Systems (AAS) in rural access networks. AAS promise to increase the overall capacity in MWN, improving the link quality while suppressing or reducing the multiple access interference. To effectively exploit the capabilities of AAS, a proper design of Medium Access Control (MAC) protocols is needed. Hence, the results of system level studies into MAC protocols and AAS are presented in this thesis. Two different MAC protocols are examined: Spatial Time Division Multiple Access (STDMA) and Carrier Sense Multiple Access Collision Avoidance (CSMA/CA) with handshaking. The effects of utilizing advanced antennas on the end-to-end network throughput and packet delay are analyzed with routing, power control and adaptive transmission data rate control separately and in combination. Many of the STDMA-related research questions addressed in this thesis are posed as nonlinear optimization problems that are solved by the technique called "column generation" to create the transmission schedule using AAS. However, as finding the optimal solution is computationally expensive, we also introduce low-complexity algorithms that, while simpler, yield reasonable results close to the optimal solution. Although STDMA has been found to be very efficient and fair, one potential drawback is that it may adapt slower than a distributed approach like CSMA/CA to network changes produced e.g. by traffic variations and time-variant channel conditions. In CSMA/CA, nodes make their own decisions based on partial network information and the handshaking procedure allows the use of AAS at the transmitter and the receiver. How to effectively use AAS in CSMA/CA with handshaking is addressed in this thesis. Different beam selection policies using switched beam antenna systems are investigated. Finally, we demonstrate how the proposed techniques can be applied in a rural access scenario in Nicaragua. The result of a user-deployed MWN for Internet access shows that the supported aggregated end-to-end rate is higher than an Asymmetric Digital Subscriber Line (ADSL) connection.QC 20100908
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Vrancken, Patrick. "Characterization of T2L2 (Time Transfer by Laser Link) on the Jason 2 ocean altimetry satellite and Micrometric laser ranging." Phd thesis, Université de Nice Sophia-Antipolis, 2008. http://tel.archives-ouvertes.fr/tel-00367703.
Full textAbstract:
Le schéma de T2L2 (Transfert de Temps par Lien Laser), basé sur la technologie de la télémétrie laser (SLR), représente un nouveau moyen pour la synchronisation d'horloges distantes. L'expérience T2L2 fut acceptée par le CNES en 2005 d'être embarqué sur le satellite d'altimétrie des mers Jason 2.La première partie de ce travail traite la caractérisation intégrale de l'instrument spatial T2L2, incluant la calibration et l'évaluation de sa performance en métrologie de temps/fréquence. Ces tests furent menée à l'aide d'un banc de test de haute complexité, développé à l'Observatoire de la Côte d'Azur.
Par ailleurs, le document décrit un bilan des performances du schéma intégrale T2L2, incluant l'instrument spatial ainsi que le segment sol et autres contributeurs ; par conséquent on démontre la performance finale de tout le transfert de temps: Avec une stabilité de quelques picosecondes en intégrant pendant un passage du satellite, T2L2 permettra de comparer les horloges les plus avancés, incluant les fontaines atomiques. L'exactitude absolue d'un transfert de temps fut déterminé à moins que 50 ps en configuration vue commune.
La deuxième partie du document présent est orientée autour l'extension de la technologie de télémétrie laser et T2L2 à la mesure absolue et de très haute résolution de distances en espace.
Cet objectif devra être atteint en utilisant un laser de peigne de fréquences en combinant la mesure de temps de vol avec une mesure interférométrique.
Le document décrit un pas important vers la faisabilité de cet approche, la mesure de distances en datation à très haute cadence et en mesure de phase, ce qui devrait permettre de franchir le seuil de la longueur d'onde.
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Erozel, Guzen. "Natural Language Interface On A Video Data Model." Master's thesis, METU, 2005. http://etd.lib.metu.edu.tr/upload/12606251/index.pdf.
Full textAbstract:
The video databases and retrieval of data from these databases have become popular in various business areas of work with the improvements in technology. As a kind of video database, video archive systems need user-friendly interfaces to retrieve video frames. In this thesis, an NLP based user interface to a video database system is developed using a content-based spatio-temporal video data model. The data model is focused on the semantic content which includes objects, activities, and spatial properties of objects. Spatio-temporal relationships between video objects and also trajectories of moving objects can be queried with this data model. In this video database system, NL interface enables flexible querying. The queries, which are given as English sentences, are parsed using Link Parser. Not only exact matches but similar objects and activities are also returned from the database with the help of the conceptual ontology module to return all related frames to the user. This module is implemented using a distance-based method of semantic similarity search on the semantic domain-independent ontology, WordNet. The semantic representations of the given queries are extracted from their syntactic structures using information extraction techniques. The extracted semantic representations are used to call the related parts of the underlying spatio-temporal video data model to calculate the results of the queries.