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1
Thomas, David A. "Laboratory rip current circulation using video-tracked lagrangian drifters." [Gainesville, Fla.] : University of Florida, 2003. http://purl.fcla.edu/fcla/etd/UFE0001217.
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Portell, Jeffrey R. "Calibration and validation of inertial measurement unit for wave resolving drifters." Thesis, Monterey, California: Naval Postgraduate School, 2013. http://hdl.handle.net/10945/38994.
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Approved for public release; distribution is unlimited.<br>We examine the performance of the Yost Engineering Incorporated 3-Space Sensor Data-Logging (TSS-DL) for use in wave resolving drifters (WRDs) that collect ocean surface wave data. We create a surface wave orbital motion simulator to test the TSS-DL in a controlled, laboratory setting at the Naval Postgraduate School. Tests are conducted in three different configurations at five frequencies within the swell and wind-sea bands. Results from the tests show that the TSS-DL can accurately resolve the vertical simulated wave motions to within37% of the analytic signal amplitude and can resolve the horizontal simulated wave motions to within2133% of the analytic signal amplitude. We further examine some field data collected using the TSS-DL onboard WRDs deployed in June 2013 near the mouth of the Columbia River. This analysis, based on comparison with independent GPS wave measurements, demonstrates that the TSS-DL yields reliable estimates of surface wave spectra and can track surface wave profiles even under extreme conditions with large breaking waves. Overall, this study shows that the TSS-DL is a suitable sensor for use in ocean surface drifters to accurately record surface waves.
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Roth, George. "Monitoring Fjord Circulation Using Iceberg-Mounted GPS as Real-Time Drifters." Thesis, University of Oregon, 2014. http://hdl.handle.net/1794/18416.
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Ocean circulation in Greenland's large glacial fjords is one mechanism that controls the rate of submarine melting at the termini of Greenland's outlet glaciers. Here we use hourly position data from GPS units deployed on ten large (>100 meter), deep-keeled icebergs in Sermilik Fjord, SE Greenland. We observe and quantify the motions of these icebergs moving through the mélange, fjord, and shelf regimes. In the mélange, icebergs move outward with glacier flow until pushed loose by large calving events. In the fjord, high frequency, low amplitude tidally-driven motions are superimposed on dominant 1-5 day events with net velocities exceeding 0.1 m/s. We interpret these events as two-layer, intermediary circulation driven by winds along the shelf, where icebergs travel southward in the East Greenland Coastal Current. These results showcase the potential of this novel instrumentation to link iceberg motion with circulation in any large glacial fjord.
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Renner, Angelika H. H. "Advection and dispersion of modelled drifters in the Weddell and Scotia Seas." Thesis, University of East Anglia, 2010. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.520436.
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BOURLESSAS, PANAGIOTIS. "Rubbish stuff, thick skins, and drifters: making homeless geographies in Athens city centre." Doctoral thesis, Gran Sasso Science Institute, 2018. http://hdl.handle.net/20.500.12571/21021.
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Being a city in and of crisis, Athens, Greece, undergoes dramatic changes in its spatialities. Amidst severe economic austerity, a new poverty management is being established in the city shaping contested landscapes of homelessness, composed by spatialities of homeless stigma. This dissertation is about these very
spatialities and the subjectivities shaped therein. And it poses two parallel, dialogic and inextricable questions under one common question mark: how are
the homeless geographies of Athens made and how are homeless subjects made along with these geographies? Seeking answers, this work draws from (post-) phenomenological geographic accounts in order to make the human geographies of homelessness of central Athens in practice-oriented, power-ridden and evidence-based manners. A multi-sited ethnographic research practice has been conducted throughout what has been called ‘machinic archipelago’ of provision and care: homeless hostels, a day centre, a night shelter as well as other organisational spaces that aim to address homelessness.
The empirics revolve around a conceptual triptych that proves critical for the practical making of Athens’ homeless geographies: Materialities— Bodies—Mobilities. These are (some of) the
critical geographic ingredients that produce social difference and ground it in space: they show how homelessness is not a fixed and static category but is lived, embodied, material, discursive, spaced. When spaced through the interrelations of these three elements, homelessness is marked as one —another— of society’s ‘Others’. Yet, what matters is that materialities, bodies and mobilities do not simply co-exist in these geographies; they are practiced therein, in specific possible ways. But they do not statically mark social difference once and forever; they constantly perform social difference and thus position it in broader social and cultural dynamics. And along with these/their geographies, homeless subjectivities are in the making too.
Materialities refers to the homeless’ possessions as ‘absent presences’ as well as the ‘objects of care’ that are provided in the machinic archipelago. In an interplay between material divestment and investment, specific objects relate to ideas of stigma; others are involved in specific political economies of provision; others undergo processes of becoming rubbish; and others, like the homeless’ own belongings, acquire emphasised importance for distinct, non-stigmatised subjects that find themselves in spaces of limited materiality. Bodies concerns homelessness as a bodily condition situated in space. In a cleanliness-dirt
interplay, the machinic archipelago enables certain bodily practices for the homeless: bodies become personal maps of the past; they are the primal instrument for adjusting to everyday survival; they receive and ingest provided food; they are made through clothes as their extensions; and they perceive critical affective atmospheres produced by the new poverty management. Lastly, mobilities concern the homeless patterns of mobility and friction that take place in the archipelago. Mentalities of managing the poor materialise in a specific ‘sense of mobility’ that is practiced as forced mobility; the homeless experience this mobility as ‘drifters’, through affect and the materiality of their bodies but also negotiate it; frictions perform ideas of stigma; and through outreach work, the machinic archipelago externalises its practices and may contribute to the making of homeless stigma.
Overall, the dissertation attempts contributions to existing scholarship in both theoretical and empirical terms. Theoretically, it brings to the fore the role of space and Human Geography in the practice-oriented and relational making of homelessness and homeless subjectivities by bringing together three geographical concepts, namely materialities, bodies and mobilities. Empirically, its contribution rests in the multi-sited qualitative research methodology conducted throughout some of Athens’ homeless spatialities that have escaped academic attention, and in the centrality of human experience thus allowing homeless subjectivities to emerge along with space. Above all, by focusing in such institutionalised spaces, homelessness is presented not as an isolated social construct but located in wider socio-cultural dynamics whereas the critical role of academic practice is highlighted in the making of homeless geographies.
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Gibson, Sean. "Investigating the feasibility of a locally developed carbon-offsetting scheme : the case of the Drifters Desert Nature Reserve." Thesis, Stellenbosch : Stellenbosch University, 2012. http://hdl.handle.net/10019.1/20210.
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Thesis (MPhil)--Stellenbosch University, 2012.<br>ENGLISH ABSTRACT: In the context of both climate change and peak oil, it is clear that the tourism industry cannot
continue with a business-as-usual approach. Unfettered fossil fuel use is no longer an option and
novel approaches need to be explored in order to change the configuration of energy systems.
Transport is particularly energy intense and consequently, since it involves travel, so is tourism.
The Drifters Desert Nature Reserve (DDNR) is probably a net carbon sink. The property is large
and has thousands of long lived trees and bushes: but this would be an ‘easy out’ in an industry
which is has a reputation for evading tough questions. Are there affordable techniques that can be
employed by the Reserve that will reduce its carbon footprint and enable it to move toward being
entirely carbon neutral, without relying on sequestration?
A willingness to pay (WTP) survey investigating if clients were prepared to pay a voluntary amount
towards reducing the emissions of the DDNR, thereby offsetting some of their own emissions, was
conducted; 121 questionnaires were completed. The results were extrapolated out to represent the
WTP of the 1055 clients that visited the DDNR in the last year. It was found that 73% of all the
clients who stay at the DDNR are willing to pay toward helping the DDNR change the way its
systems are configured as a means to offset some of their own emissions debt in getting to the
reserve. Lodge clients were prepared to pay almost double the amount clients staying at the
campsite would consider. In both cases, WTP was around 10% of the value of the accommodation
package chosen.
The fossil fuel use and consequent carbon dioxide debt of the DDNR was calculated and
emissions were found to be in the region of 30 tonnes per annum. As per the case in the greater
Namibia, transport is responsible for the bulk of the carbon dioxide output, with energy provision in
this off-grid reserve being a close second. Of four potential interventions considered, two were
found to be financially viable, regardless of the WTP of clientele.
It is speculated that WTP on a small scale is administratively laborious and the potential
contribution of a voluntary offsetting payment was perhaps not high to justify the implementation of
the scheme. It was however found that reconfiguring the energy systems would definitely be a
worthwhile exercise.
On corporate level where efficiencies of size amplify gains, Drifters, as a group of 14 lodges and an
overland company, may well find that a transparent voluntary emissions reduction (VER) payment,
ring-fenced, appropriately used, and properly implemented, is worthwhile.
Ethically, however, injecting VER payments into a balance sheet is problematic, especially where
the payback period of the technological interventions is short and the benefits derived are long
term.<br>AFRIKAANSE OPSOMMING: Die gebruik van fossielbrandstowwe wat in die huidige tydsgewrig tot die opwekking van oormatige
kweekhuisgasse lei is nie langer aanvaarbaar nie en innoverende opsies om die voortgesette
generasie van energie te verseker, sal nagestreef moet word. Een van die grootste verbruikers van
energie is vervoer, en vervolgens is dit ook die geval dat toerisme, wat swaar op vervoer
staatmaak, ‘n groot gebruiker van energie is.
Aangesien daar etlike gevestigde bome en bosse op hierdie woestynreservaat is, is die Drifters
Desert Nature Reserve (DDNR) moontlik ‘n netto bespaarder van koolstofgasse, maar dit kan nie
sondermeer daargelaat word in ‘n bedryf wat bekend is daarvoor dat dit graag die moeilike vrae
vermy nie. Daar is dus gevra: is daar bekostigbare tegnieke wat moontlik by die DDBR aangewend
kan word om die koolstofvoetafdruk te verminder en dit in staat kan stel om totaal koolstofneutraal
te word, sonder om op ingryping staat te maak?
Navorsing is gedoen en 121 vraelyste is voltooi om vas te stel of kliente gewillig sou wees om ‘n
vrywillige bydrae te maak om die afskeid van koolstof te beheer en daardeur hul eie
koolstofvoetafrdruk te verminder, in ‘n sg “gewilligheid om te betaal” oftewel “willingness to pay”
(WTP) opname. Die resultate is deurgevoer as verteenwoordigend van die 1 055 kliente wat
verlede jaar die oord besoek het. Daar is gevind dat 73% van die kliente wat die oord besoek
bereid sou wees om die DDNR geldelik te help om sy stelsels te verander as ‘n teenrekening om
hul eie koolstofbesoedeling op pad daarheen te vergoed. Kliente wat die losie gebruik het was
bereid om meer te betaal as diegene wat by die kampeerterrein tuisgegaan het.
Die hele reservaat se jaarlikse koolstofdioksied debiet is bereken, en die jaarlikse opwekking is op
ongeveer 30-tonne vasgestel. Nes in Namibie as geheel is vervoeruitlaatgasse verantwoordelik vir
die oorgrote meerderheid opwekking, met die voorsiening van energie by die afgelee oord kort op
sy hakke. Van die vier moontlike ingrypings wat oorweeg is, is twee finansieel die moeite werd
gevind, ongeag die kliente se gewilligheid om geldelik by te dra. Die bestuur van aanvraag is ook
oorweeg, en hoewel dit nie gekwantifiseer is nie, is dit nes die moontlikheid van tegnologiese
innovering, duidelik deel van die oplossing,
Daar is gevind dat ‘n stelsel van betaling op plaaslike vlak moeilik sou wees om die administreer,
en aangesien selfs die gewilliges nie oorgretig is nie, is daar tot die gevolgtrekking gekom dat dit
nie die moeite sou loon nie. Ongeag bogenoemde beginsel van toersitebydraes is daar gevind dat
dit ongetwyfeld die moeite werd sou wees om die energiestelsels aan te pas. Maar dit sal nie
noodwendig op ‘n korporatiewe of ‘n makro-skaal werk nie, veral nie waar grote ‘n rol speel nie. As
maatskappygroep mag Drifters vind dat met ‘n deursigtige, vrywillige uitlaatverminderingspaaiement,
wat afgebaken, korrek aangewend en effektief bestuur word, die kool die
sous werd sou wees.
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Fiorentino, Laura A. "Using Lagrangian Coherent Structures to Study Coastal Water Quality." Scholarly Repository, 2011. http://scholarlyrepository.miami.edu/oa_theses/267.
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In order to understand water quality in the coastal ocean and its effects on human health, the necessity arises to locate the sources of contaminants and track their transport throughout the ocean. Dynamical systems methods are applied to the study of transport of enterococci as an indicator of microbial concentration in the vicinity of Hobie Beach, an urban, subtropical beach in Miami, FL that is used for recreation and bathing on a daily basis. Previous studies on water quality have shown that Hobie Beach has high microbial levels despite having no known point source. To investigate the cause of these high microbial levels, a combination of measured surface drifter trajectories and numerically simulated flows in the vicinity of Hobie Beach is used. The numerically simulated flows are used to identify Lagrangian Coherent Structures (LCSs), which provide a template for transport in the study area. Surface drifter trajectories are shown to be consistent with the simulated flows and the LCS structure. LCSs are then used to explain the persistent water contamination and unusually high concentrations of microbes in the water off of this beach as compared with its neighboring beaches. From the drifter simulations, as well as field experiments, one can see that passive tracers are trapped in the area along the coastline by LCS. The Lagrangian circulation of Hobie Beach, influenced primarily by tide and land geometry causes a high retention rate of water near the shore, and can be used to explain the elevated levels of enterococci in the water.
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Sheridan, Megan. "Mixing and dispersion of a small estuarine plume." Thesis, University of Plymouth, 2018. http://hdl.handle.net/10026.1/12817.
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Entrainment velocity, salt flux and the turbulent diffusivity of salt are estimated in the outflow of a small, radially spreading buoyant outflow, just outside of the Teign Estuary mouth, as a means to compare mixing dynamics between very small and larger-scale estuarine and river plumes, and build on a scant knowledge base regarding the former. The analysis was made using a control volume approach, based on the conservation of momentum, volume and salt, from a Lagrangian perspective. Drifting buoys were used to accomplish this. The analysis was based on that employed by McCabe et al. (2008), with some modifications to fit a small-scale outflow, namely: repeat deployments, shorter drifter tracks, and deployment-specific criteria used for choosing the plume base, a step in the analysis used to calculate vertical entrainment, flux and diffusivity. In addition, temperature was used as a proxy for salinity, and this is evaluated in the results. Overall results were compared to a similar study, which was conducted in the Columbia River plume, a system much larger in scale to the Teign. Drifter experiments were conducted on multiple days, under different conditions (i.e. wind, tides, river flow), and those results are discussed briefly, but the focus is on one specific day, April 3, 2014, where conditions most closely matched those of the comparison study, and those results are compared between the two systems. Entrainment velocity was measured along the drifter tracks, in the near-field plume, where shear-induced mixing dominates. Drifter track subsections were chosen so as to avoid source or frontal dynamics, the plume base was chosen for individual deployments as the plume dynamics could change relatively quickly, and repeat deployments were conducted as a way to look at near-field plume evolution over the course of the ebb (and with a smaller plume, time allowed for this) . On April 3, the mean value for entrainment velocity for the four deployments chosen in the Teign outflow was 4.3 x 10-4 ms-1. The mean cast value was slightly higher at 7.6 x 10-4 ms-1, as casts values were typically measured at the beginning of the drifter tracks. Entrainment values at the cast sites were calculated in the same way as the track values, taking plume thickness from hydrographic casts, as a means to evaluate accuracy of track values, which are based on a modelled plume thickness. A rough estimate for the mean entrainment velocity for one pair of drifters used in the Columbia River was 9 x 10-4 ms-1, approximately double that of the Teign, but within the same order of magnitude. Salt flux values ranged from 0-5 x 10-2 psu ms-1 and from 0-3 x 10-2 psu ms-1 for the Teign and the Columbia, respectively, and diffusivities ranged from 0.5-5.8 x 10-2 m2s-1 and from 0.2-9.6 x 10-3 m2s-1. With a similar range of entrainment and salt flux values, and almost an order of magnitude difference between diffusivity values, it was determined that weaker density gradients in the Teign are responsible for the latter, and that this increased level of mixing results in a larger horizontal horizontal salinity gradient, which balances out the terms in the entrainment equation that are related solely to the physical size of the system (i.e. plume thickness, velocity and the vertical salinity gradient). This higher level of mixing of a smaller physical entity, supports the view that smaller plumes mix more thoroughly over a shorter timescale, resulting in a larger impact to the local environment into which they flow.
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ADISSI, FLÁVIA. "THE CONTRIBUTION OF OCEAN DRIFTERS AND NUMERICAL SIMULATIONS OF OCEAN CURRENTS AND WINDS IN SUPPORT OF THE TERRITORIAL PLANNING: THE CASE OF GUANABARA BAY." PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO, 2016. http://www.maxwell.vrac.puc-rio.br/Busca_etds.php?strSecao=resultado&nrSeq=27618@1.
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Este trabalho aborda a questão da movimentação e acúmulo do lixo flutuante
na Baía de Guanabara e contextualiza a problemática da poluição da Baía e seu
entorno a partir de diversos temas inter-relacionados, como: o uso dos derivadores
e a sua analogia com o lixo flutuante; a existência de projetos que têm ajudado no
rastreamento do lixo flutuante na Baía a partir do mapeamento de correntes
superficiais e ventos; o saneamento da bacia hidrográfica da Baía, a qualidade da
água de seus afluentes e a análise da população que reside no seu entorno; o
entendimento de uma visão mais humanista e ecológica no redesenho das cidades
e também programas internacionais de revitalização de corpos d água degradados.
Dentro deste contexto, são feitas reflexões e análises integradas a partir de uma
modelagem da probabilidade de transporte de resíduos da Baía e da paisagem
encontrada em seu entorno, através da utilização de produtos cartográficos. Tais
análises consideram os dados levantados nos quatro mapas que são apresentados,
de forma a prover uma visão mais ampla e integrada do espelho d água e também
do entorno da Baía. O objetivo deste trabalho foi entender como o espaço territorial
e a ocupação urbana do entorno da Baía podem impactar a poluição do espelho
d água da Baía e por ela serem impactados de forma a contribuir com programas de
despoluição. Foi feito então um recorte em quatro regiões e realizada uma análise
integrada para cada, de forma a prover um melhor entendimento a partir da
exemplificação. A análise integrada proporciona uma visão mais abrangente da
questão da poluição, auxiliando os gestores dos programas de despoluição a
encontrarem relevantes informações para priorizar as ações a serem tomadas.<br>This work approaches the issue of the movement and accumulation of floating litter in the Guanabara Bay, in Rio de Janeiro, Brazil. It contextualizes the problem of the pollution in the Bay and surroundings, and it does so from several different interrelated issues, such as the use of ocean drifters and their analogy with the floating litter; the existence of projects that have been helping in the tracking of the floating litter in the Bay from the mapping of the surface currents and the winds; the sanitation efforts in the hydrographic basin of the Bay; the quality of the water in the rivers that debouch into the Bay and a better understanding of the population that live in the area; the necessity of a more humanistic and ecological view in the planning of those cities; and also international programs to revitalize degraded water bodies. One of the objectives of this dissertation is to understand how the territorial space and the urban occupation of the Bay s surroundings can impact the pollution in the Bay and be impacted by that pollution. So the entire region was divided in four areas and an integrated analysis was made for each area so that a better understanding could be provided by exemplification. Such integrated analysis provides a more comprehensive view of the pollution problem and helps the depollution program officers to find relevant information and better prioritize actions. The Guanabara Bay plays a strategic role not only around the towns and cities that are part of its hydrographic basins, but in the whole state of Rio de Janeiro and also the entire country. It is one of the most important marine ecosystems from the social, economic and environmental points of view. It is located in the Rio de Janeiro city metropolitan area, with the Brazilian coast s largest population concentration (about 10 million people, or 80 percent of the state s population). A national security area, the Bay shelters two naval bases, one navy shipyard, the Rio de Janeiro Port (the second largest in the country, with more than 2 thousand ship moorings annually), two airports (Antonio Carlos Jobim, and Santos Dumont), and other shipyards and marinas. The Guanabara Bay is also way for innumerous cargo and passenger ferryboats, fishing boats, and other boats for leisure and tourism. The water in the Bay is also used for water sports and aquaculture (fish farming). (KJERFVE, 1997; BERGAMO, 2006 apud CARVALHO, 2011).
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Johnson, David. "The spatial and temporal variability of nearshore currents." University of Western Australia. Centre for Water Research, 2004. http://theses.library.uwa.edu.au/adt-WU2004.0067.
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The nearshore current field, defined here as the residual horizontal flow after averaging over the incident wave period, exhibits variability at a range of time and space scales. Some of the variable currents are low frequency gravity wave motions. However, variable, rotational (in the sense of possessing vertical vorticity) flow can also exist as part of the overall nearshore current field. A field and numerical modelling investigation of these variable rotational currents has been carried out. Drifters, which were developed for surfzone use, enabled measurement of the nearshore current structure; the design and testing of these new instruments is described. Two sets of field measurements, using the new drifters and Eulerian instruments were carried out for conditions with swell perpendicular to a plane beach and in strong longshore currents. In the perpendicular swell conditions, an interesting and well-defined feature of the measured trajectories was the development of transient rip currents. Discrete vortices were also observed. In the longshore current case, trajectories with the longshore current displacement removed had complex meandering paths. Lagrangian data were used to make estimates of length scales and dispersion, both of which provide strong evidence that the current field cannot be due to low frequency gravity waves alone. Under the assumption of equipartition of kinetic and potential energy for low frequency gravity waves, Eulerian measurements of velocities and pressure show significant energy due to non-divergent, rotational flow in both the perpendicular swell and longshore current case. A numerical model that can simulate horizontal flow with a directionally spread, random wave field incident on a plane beach was implemented. The model developed transient rip currents that are qualitatively very similar to those seen in the drifter trajectories from the field. The number and intensity of rip currents in the model depended on the beach slope and incident wave spectra. The energy content and cross-shore flux (and hence transport of material) of the rotational current flow component in the simulated flow fields is comparable to that due to low frequency gravity waves. The modelling also provided some evidence that there may be universal characteristics of the rotational currents. The field results and modelling show that variable rotational currents are ubiquitous in the field even when longshore currents and hence shear waves are not present. The term “infragravity turbulence” is suggested to describe the general class of nearshore hydrodynamics not directly associated with shear waves, which is largely disorganised, but contains well defined features such as transient rips currents and large scale horizontal vortices. The results have important implications in the understanding of the transport of material, including sediment, biological material, pollution, and sometimes bathers, in the nearshore zone.
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Baaklini, Georges. "Characterization of the Eastern Mediterranean surface dynamics : Insights from drifter assimilation and machine learning techniques." Electronic Thesis or Diss., Sorbonne université, 2022. http://www.theses.fr/2022SORUS186.
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Une estimation précise de la circulation de surface est cruciale en raison de son impact direct sur les propriétés physiques et bio-géochimiques du du milieu marin. Cependant, l’estimation des courants reste un défi car le champ de circulation est affecté par des flux qui changent rapidement. Ce problème s’accentue en Méditerranée orientale, où les observations in-situ sont relativement rares et où les imprécisions des observations altimétriques augmentent. Par conséquent, certaines des caractéristiques de méso-échelle sont encore débattues ou inconnues, en particulier dans le bassin levantin. L’objectif de la thèse est de caractériser ces structures méso-échelles hautement évolutives dans la mer Méditerranée. Dans la première partie de la thèse, nous présentons une méthode d’assimilation variationnelle qui fusionne l’altimétrie satellitaire avec les observations des bouées pour améliorer la représentation de la circulation de surface le long et autour des trajectoires des bouées assimilées. Nous évaluons l’efficacité de la méthode en comparant les vitesses résultant de l’assimilation avec des observations in-situ indépendantes et des images couleur de l’océan. Nous utilisons ensuite les vitesses corrigées pour caractériser les événements locaux et à court terme qui se produisent dans le bassin du Levant. Cependant, en raison des lacunes spatio-temporelles importantes dans la couverture des bouées, l’assimilation ne permet pas une investigation continue de toutes les structures mésoéchelles et de leurs variabilités à long terme dans le bassin. Dans la deuxième partie de la thèse, nous présentons des techniques de “machine learning” qui seront utilisées pour construire un catalogue des différents régimes de circulation dans le bassin levantin, permettant ainsi la caractérisation à long terme de ces structures. Nous essayons également d’expliquer les raisons possibles derrière les évaluations contradictoires précédentes de certaines structures, comme par exemple, le “Mid-Mediterranean Jet”. Les résultats obtenus dans cette thèse améliorent la connaissance des caractéristiques,des comportements et des tendances des principales structures méso-échelle. Les applications de la thèse pourraient tirer profit d’autres observations in-situ et de futures missions altimétriques comme SWOT, promettant ainsi de pallier certaines des lacunes actuelles de l’altimétrie<br>An accurate estimation of the surface circulation is crucial because of its direct impact on physical and bio-geochemical water properties. However, currents estimation remains challenging because the stream field is affected by quickly changing flows. This problem increases in the Eastern Mediterranean Sea, where in-situ observations are relatively scarce and the inaccuracies of altimetric observations increase. Therefore, some of the mesoscale features are still debated or unknown, especially in the Levantine Basin. The thesis goal is to characterize these highly-evolving mesoscale features. In the first part of the thesis, we present a variational assimilation method that merges altimetry with drifters to improve the surface circulation representation along and around the assimilated drifters’ trajectories. We assess the method’s efficiency by comparing the velocities resulting from assimilation with independent in-situ observations and ocean color images. We use the corrected velocities to characterize short-term and local events occurring in the Levantine Basin. However, because of the significant spatio-temporal gaps in drifters’ coverage, the assimilation does not allow a continuous investigation of all the mesoscale patterns and their long-term variabilities in the basin. In the second part of the thesis, we use machine learning techniques to build a catalog of the several circulation regimes in the Levantine Basin, providing a long-term characterization of these features. We also try to explain the possible reasons behind previous contradictory assessments about some features, such as the Mid-Mediterranean Jet. The obtained results in the thesis improve the knowledge of the main mesoscale features’ characteristics, behaviors, and tendencies. The thesis applications could take advantage of other in-situ observations and of future altimetric missions like SWOT, promising to mitigate some of the actual altimetric shortcomings
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Suara, Kabir Adewale. "Development and use of GPS-based technology to study dispersion in shallow water." Thesis, Queensland University of Technology, 2017. https://eprints.qut.edu.au/102841/1/Kabir%20Adewale_Suara_Thesis.pdf.
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This project was a step forward for the measurement and management of shallow water estuaries using satellite technology. Newly developed Global Positioning System (GPS) high resolution drifters were used to investigate the flow field and the spreading behaviours of passive particles. It identified the dominant mechanisms responsible for the tidal scale spreading with a focus on tidal estuaries in Southeast Queensland. Importantly, this study provides a unique moving sensor (Lagrangian) approach to strengthen current modelling efforts in prediction of the transport of materials in tidal estuaries. This new approach provides a unique complement to the traditional fixed sensor (Eulerian) approach.
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Ukita, Jinro. "Drifter observations in the Northeast Pacific." Thesis, University of British Columbia, 1987. http://hdl.handle.net/2429/26653.
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From the position data of 23 drifters over the four years period, 1982 to 1985, the upper layer kinematics of the Northeast Pacific were investigated. The focus of this study was upon the topographic influence, wind forcing, and Rossby waves. The notions of homogeneity and stationarity were applied to both the Eulerian and Lagrangian analysis. A new computational scheme was proposed and tested in order to explicitly take into account the Lagrangian characteristics of the drifter data. The Eulerian analysis showed that the spatial and temporal distributions of the mean current and the mean wind stress were in good agreement. Three of the four eddy kinetic energy maxima found in the region geographically corresponded to topographic features. Also the velocity field of this region appeared to be strongly inhomogeneous, non-stationary, and anisotropic. The results from the Lagrangian analysis showed that the spectral slope for the periods shorter than 5 days followed the -2 law, and suggested that the direct wind forcing was a dominant mechanism for those periods. The spectrum of the eddy component of the velocity appeared to be white for the periods longer than 10 days. The results showed that the linear Rossby waves were not dominant mechanism for upper layer dynamics of this region. The rotary spectra illustrated some evidence of the rotational preference of the cyclonic over anti-cyclonic motions at a period of 10 days. The new scheme provided meaningful information about the eddy component of the velocity.<br>Science, Faculty of<br>Earth, Ocean and Atmospheric Sciences, Department of<br>Graduate
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Mauerhan, Todd A. "Drifter observations of the Mediterranean Sea surface circulation/." Thesis, Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 2000. http://handle.dtic.mil/100.2/ADA378053.
Full textAbstract:
Thesis (M.S. in Physical Oceanography) Naval Postgraduate School, March 2000.<br>Thesis advisor(a): Poulain, Pierre-Marie. "March 2000." Includes bibliographical references (p. 109-111). Also available online.
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Brown, John E. M. "Drifter-based velocity statistics in the vicinity of the Azores Front." Thesis, Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 1995. http://handle.dtic.mil/100.2/ADA307669.
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Thesis (M.S. in Meteorology and Physical Oceanography) Naval Postgraduate School, December 1995.<br>Thesis advisor(s): Jeffrey D. Paduan. "December 1995." Bibliography: p. 143-148. Also available online.
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Wright, James M. "Stable processes with opposing drifts /." Thesis, Connect to this title online; UW restricted, 1996. http://hdl.handle.net/1773/5807.
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Vogt, Jason A. "Adriatic Sea surface temperature : satellite and drifter observations, May to October, 1995." Thesis, Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 1999. http://handle.dtic.mil/100.2/ADA362509.
Full textAbstract:
Thesis (M.S. in Physical Oceanography) Naval Postgraduate School, March 1999.<br>Thesis advisor(s): Pierre-Marie Poulain. "March 1999". Includes bibliographical references (p. 85-86). Also available online.
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Leitz, Jeffrey M. "Ionian Sea surface temperature :satellite and drifter observations, May to October, 1995 /." Thesis, Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 1999. http://handle.dtic.mil/100.2/ADA371279.
Full textAbstract:
Thesis (M.S. in Physical Oceanography) Naval Postgraduate School, September 1999.<br>"September 1999". Thesis advisor(s): Pierre-Marie Poulain. Includes bibliographical references (p. 87-88). Also available online.
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McIntyre, Stephen A. "WAVE AND CURRENT OBSERVATIONS IN A TIDAL INLET USING GPS DRIFTER BUOYS." Monterey, California. Naval Postgraduate School, 2013. http://hdl.handle.net/10945/32869.
Full textAbstract:
The Wave Resolving Drifter (WRD) Buoy, developed at NPS, was refined by adding an accelerometer and utilizing horizontal Doppler velocity measurements to better resolve the wave surface motions. The WRD Buoy was validated against a Datawell Waverider-GPS buoy by comparing bulk wave statistics, wave energy spectra and wave directional spectra. The validation was performed in deep water, offshore of Monterey Bay, CA. Horizontal measurements from Doppler velocities showed improved capability, particularly in the wind-wave band. Vertical measurements were significantly improved through the addition of the accelerometer. A large array of WRD buoys was deployed in the Golden Gate channel at the entrance to San Francisco Bay and allowed to drift with the outgoing ebb current. The simultaneous deployment of many drifters provides a unique view of the details of the temporal and spatial evolution of the wave field as it propagated through regions of bathymetric and wave-current interactions. Wave heights increased as the wave field propagated over the ebb-tidal shoal and at the entrance to the channel, in the presence of a strong opposing ebb current, as expected. Inside the channel, strong dissipation of high frequency wind waves was observed in the opposing current.
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Bilisoly, Roger. "Estimating mesoscale ocean currents from drifter trajectories using a spatiotemporal Bayesian statistical model /." The Ohio State University, 1998. http://rave.ohiolink.edu/etdc/view?acc_num=osu1487949836205445.
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Khanarmuei, Mohammadreza. "Improving flow characterisations in complex estuary and coastal waterways using Lagrangian drifter data." Thesis, Queensland University of Technology, 2021. https://eprints.qut.edu.au/225939/1/Mohammadreza_Khanarmuei_Thesis.pdf.
Full textAbstract:
By utilising new measurement technologies and advances in numerical models, especially through the use of open-source software, this project paves a way for the better understanding of estuarine hydrodynamics. Using state-of-the-art GPS-tracked drifters and an ensemble-based data assimilation approach, this research presents several novel methods to improve the accuracy of hydrodynamic models for shallow estuaries. It opens new opportunities for researchers/engineers to use Lagrangian data to better employ hydrodynamic models to understand real-time and future estuarine dynamics.
22
Zhou, Huajun. "Multivariate compound point processes with drifts." Online access for everyone, 2006. http://www.dissertations.wsu.edu/Dissertations/Summer2006/h%5Fzhou%5F051606.pdf.
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Elipot, Shane. "Spectral characterization of Ekman velocities in the Southern Ocean based on surface drifter trajectories." Diss., Connect to a 24 p. preview or request complete full text in PDF format. Access restricted to UC campuses, 2006. http://wwwlib.umi.com/cr/ucsd/fullcit?p3236917.
Full textAbstract:
Thesis (Ph. D.)--University of California, San Diego, 2006.<br>Title from first page of PDF file (viewed December 7, 2006). Available via ProQuest Digital Dissertations. Vita. Includes bibliographical references (p. 119-126).
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Ottone, Dauvin Sergio Andrés. "Comportamiento en postcosecha de cvs. de lechuga (Lactuca sativa L.) GX906, Drifter y Valencia." Tesis, Universidad de Chile, 2014. http://repositorio.uchile.cl/handle/2250/148810.
Full textAbstract:
Memoria para optar al Título Profesional de: Ingeniero Agrónomo<br>Las lechugas tipo “baby” (Lactuca sativa L.) cvs. GX906 (Romana verde), Drifter
(Mantecosa) y Valencia (hoja Roble roja), cultivadas bajo sistema hidropónico en
primavera fueron cosechadas, caracterizadas y sometidas a 6 tratamientos distintos para
evaluar sus respuestas a un almacenaje de 10 días a 4ºC y 90% HR más 1 día a 10ºC y 75%
HR, simulando el período de almacenamiento y de comercialización respectivamente. Para
la caracterización de las lechugas se tomó en cuenta peso, tamaño, longitud de tallo, color y
forma de hoja. Para el estudio se diseñaron 3 ensayos, uno para cada cultivar, y los
tratamientos realizados consistieron en envasar las lechugas por separado en bolsas
confeccionadas con diferentes películas plásticas transparentes y selladas: a) polietileno de
baja densidad de 0,03mm de espesor íntegro (PE); b) polietileno de baja densidad de
0,03mm de espesor perforado (PEP) como testigo y c) poliolefina coextruida de
0,015mm de espesor (PD961, Cryobac). Previo al envasado, a la mitad de ellas se les
realizó 1 lavado con agua potable a 17ºC por 1 minuto y luego una inmersión en agua
potable a 5ºC por 15 segundos. Y posteriormente fueron centrifugadas a 750 rpm por 2
minutos. En las mediciones realizadas el día 11 de almacenaje, se evaluó el efecto del
lavado previo y de las distintas atmósferas modificadas sobre la pérdida de peso, desarrollo
del tallo, color, turgencia, pudrición y desórdenes fisiológicos de las lechugas en estudio.
Además se midió a los 10 y 11 días de almacenaje la concentración de O2, CO2 y etileno al
interior de las bolsas.
Bajo las condiciones del estudio se concluye que el lavado previo al envasado no mejoró el
período de postcosecha, debido a que las pudriciones aumentaron. Se observó en las
lechugas conservadas en bolsa PEP la peor condición en postcosecha. Los otros dos
envases presentaron resultados similares; menores pérdidas de peso, mayor turgencia y
menores cambios de color. Estos resultados demostrarían los beneficios de la atmósfera
modificada (AM) sobre la calidad de lechugas en postcosecha.
Durante el almacenamiento no se presentaron desórdenes fisiológicos en las lechugas,
encontrándose en buenas condiciones para su consumo.<br>Baby lettuces GX906 (Green Romaine), Drifter (Butterhead) and Valencia (Red Oak leaf)
cvs. cultivated under hydroponic system in spring season, were harvested and subjected to
six different treatments to evaluate their response during a cold storage of ten days at 4°C
and 90% RH followed by one day at 10°C and 75% RH, simulating storage and marketing
periods of this product, respectively. Three essays were designed, one for each cultivar. In
each essay three atmosphere gas compositions were evaluated using translucent plastic
bags made by: a) low density polythene bags, 0,03mm of thickness (PE); b) perforated low
density polythene bags, 0,03mm of thickness (PEP), as control; and c) co extruded
polyolefin bags, 0,015mm of thickness (PD961, Cryobac). Half of the lettuces received a
rinse and an immersion in tap water before packaging; the first was at 17°C water
temperature for one minute and the second at 5°C water temperature for 15 seconds. After
that, they were centrifuged for two minutes at 750 rpm. On day 11 gas composition inside
the bags, dehydration, stem length, color, turgor, decay and physiological disorders were
evaluated. The CO2, O2 and ethylene levels were also measured on day 10 and 11.
Under the conditions of this study it is concluded that the water immersion before
packaging did not extend the shelf life of lettuces, due to decay was increased. Lettuces in
PEP bags showed the worst postharvest condition. The other two packages showed similar
results; low weight loss, good turgor and low color changes being the modified atmosphere
recommended to lettuce during cold storage.
In the study the lettuces did not show signs of physiological disorders after the eleven days
of storage, being the three essay lettuces in good conditions.
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Sjödin, Anton, and Rasmus Hagman. "Geoanläggning i Nya Krokslätt – Beskrivning och utvärdering av driften." Thesis, Högskolan i Borås, Akademin för textil, teknik och ekonomi, 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:hb:diva-14980.
Full textAbstract:
När krav på fler förnyelsebara energikällor ställs har teknikområdet geoenergi succesivt utvecklats för att med berggrundens egenskaper och kylvärmepumpar förse såväl värme- som kylbehov inom olika sektorer. Då sektorn bostäder och fastigheter stod för cirka 40 % av Sveriges totala slutgiltiga energianvändning år 2015 finns möjligheter att utvecklingen av geoanläggningar ska kunna minska miljöpåverkan samtidigt som det sänker energianvändningen såväl som kostnader. På beställning av Husvärden AB byggdes geoanläggningen Mediacentralen i området Nya Krokslätt i Mölndal. Tre kylvärmepumpar i anläggningen förser området med kyla och värme året runt. Mediacentralen inrymmer ett stort antal komponenter som är vitala för att upprätthålla driften för såväl kyl- som värmedrift. Syftet med detta arbete är att åskådliggöra och beskriva hur en större bergvärmeanläggning i Nya Krokslätt fungerar samt utreda hur driften har varit och ifall det finns förbättringar att utföra. Genom att erhålla mätvärden från anläggningen och behandla dessa med olika program- och mjukvaror kan analyser av enskilda komponenter såväl som den generella driften utföras. Under arbetets gång har det inte framkommit några konkreta problem i driften av Mediacentralen, däremot har det kunnat fastslås att insamlingen av mätdatan är bristfällig och att förbättringsmöjligheterna försvåras på grund av detta. Skillnaden i drifttiden mellan två av kylvärmepumparna är i storleken 3000 timmar sen driftsättningen av anläggningen 2015. Detta tyder på fel i mätvärdesloggningen, då mätvärden beträffande energianvändning och kapacitet visar motsatsen. Även kylvärmepumparnas värmefaktor, det mått som ger deras effektivitet, skiljer sig markant från månad till månad vilket ger en indikation om att något kan förbättras på lång sikt.<br>When demands are made for more renewable energy sources, the geoenergy technology has been developed gradually to provide heating and cooling in the various sectors with the bedrocks properties and heat pumps. Since the housing and real estate sector accounted for about 40% of Sweden's total final energy use in 2015, opportunities for the development of geo-plants can reduce environmental impact while reducing energy useage as well as costs. At the request of Husvärden AB, the geo-plant called Mediacentralen was built in the Nya Krokslätt area in Mölndal. Three refrigeration heat pump in the plant provides the area with cooling and heating all year round. Mediacentralen houses a large number of components that are vital for maintaining the operation of both cooling and heating operations. The purpose of this work is to illustrate and describe how a larger geothermal-plant in New Krokslätt works, as well as investigate how the operation has been and if there are improvements to perform. By obtaining measurement values from the plant and processing them with various software, analyzes of individual components as well as the general operations can be performed.During the course of the work no concrete problems have been encountered in the operation of the Mediacentral. On the other hand, it has been found that the collection of the measurement data is insufficient and that the improvement possibilities were aggrivated by this. The difference in operating time between two of refrigeration heat pumps is 3000 hours since the commissioning of the facility 2015 indicates errors in the measurement value logging, as the measurement of energy use and capacity shows the opposite. Even the heat factor of the refrigeration heat pump, the measure that provides their efficiency, differs significantly from month to month, giving an indication that something can be improved in the long run.
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O'loughlin, Benjamin. "Evaluation of Search and Rescue Planning Tools on the West Florida Shelf." Scholar Commons, 2016. http://scholarcommons.usf.edu/etd/6557.
Full textAbstract:
The Coast Guard conducts over 20,000 search and rescue cases a year with approximately 5% of them occurring within the coastal waters of the West Florida Shelf (WFS). Each search effort is planned using the Coast Guard’s Search and Rescue Optimal Planning System (SAROPS) which uses model inputs to create composite probability distributions based on the results of Monte Carlo projections of thousands of particle trajectories. However, SAROPS is limited by the quality of model inputs and their associated errors. This study utilizes observations from three surface drifter deployments on the WFS to evaluate the effectiveness of available surface current models, including one model not currently in use by the Coast Guard. Additionally, the performance of high-frequency (HF) Radar observations is evaluated against the models. The HF Radar root-mean-square errors (RMSE) were found to be on the order of 10 cm/s, and a model created with objectively mapped HF Radar data was found to out-perform all available models. Additionally, a comparison of model skills (using a normalized Lagrangian separation method) showed the West Florida Coastal Ocean Model (WFCOM) to have better skill on both the inner and outer shelf regions of the WFS when compared to other models.
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SANTOS, Silas Garrido Teixeira de Carvalho. "Avaliação criteriosa dos algoritmos de detecção de concept drifts." Universidade Federal de Pernambuco, 2015. https://repositorio.ufpe.br/handle/123456789/17310.
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Previous issue date: 2015-02-27<br>FACEPE<br>A extração de conhecimento em ambientes com fluxo contínuo de dados é uma atividade que
vem crescendo progressivamente. Diversas são as situações que necessitam desse mecanismo,
como o monitoramento do histórico de compras de clientes; a detecção de presença por meio
de sensores; ou o monitoramento da temperatura da água. Desta maneira, os algoritmos
utilizados para esse fim devem ser atualizados constantemente, buscando adaptar-se às
novas instâncias e levando em consideração as restrições computacionais. Quando se
trabalha em ambientes com fluxo contínuo de dados, em geral não é recomendável supor
que sua distribuição permanecerá estacionária. Diversas mudanças podem ocorrer ao longo
do tempo, desencadeando uma situação geralmente conhecida como mudança de conceito
(concept drift). Neste trabalho foi realizado um estudo comparativo entre alguns dos
principais métodos de detecção de mudanças: ADWIN, DDM, DOF, ECDD, EDDM, PL e
STEPD. Para execução dos experimentos foram utilizadas bases artificiais – simulando
mudanças abruptas, graduais rápidas, e graduais lentas – e também bases com problemas
reais. Os resultados foram analisados baseando-se na precisão, tempo de execução, uso
de memória, tempo médio de detecção das mudanças, e quantidade de falsos positivos e
negativos. Já os parâmetros dos métodos foram definidos utilizando uma versão adaptada
de um algoritmo genético. De acordo com os resultados do teste de Friedman juntamente
com Nemenyi, em termos de precisão, DDM se mostrou o método mais eficiente com as
bases utilizadas, sendo estatisticamente superior ao DOF e ECDD. Já EDDM foi o método
mais rápido e também o mais econômico no uso da memória, sendo superior ao DOF,
ECDD, PL e STEPD, em ambos os casos. Conclui-se então que métodos mais sensíveis
às detecções de mudanças, e consequentemente mais propensos a alarmes falsos, obtêm
melhores resultados quando comparados a métodos menos sensíveis e menos suscetíveis a
alarmes falsos.<br>Knowledge extraction from data streams is an activity that has been progressively receiving
an increased demand. Examples of such applications include monitoring purchase history
of customers, movement data from sensors, or water temperatures. Thus, algorithms used
for this purpose must be constantly updated, trying to adapt to new instances and taking
into account computational constraints. When working in environments with a continuous
flow of data, there is no guarantee that the distribution of the data will remain stationary.
On the contrary, several changes may occur over time, triggering situations commonly
known as concept drift. In this work we present a comparative study of some of the main
drift detection methods: ADWIN, DDM, DOF, ECDD, EDDM, PL and STEPD. For
the execution of the experiments, artificial datasets were used – simulating abrupt, fast
gradual, and slow gradual changes – and also datasets with real problems. The results
were analyzed based on the accuracy, runtime, memory usage, average time to change
detection, and number of false positives and negatives. The parameters of methods were
defined using an adapted version of a genetic algorithm. According to the Friedman test
with Nemenyi results, in terms of accuracy, DDM was the most efficient method with
the datasets used, and statistically superior to DOF and ECDD. EDDM was the fastest
method and also the most economical in memory usage, being statistically superior to
DOF, ECDD, PL and STEPD, in both cases. It was concluded that more sensitive change
detection methods, and therefore more prone to false alarms, achieve better results when
compared to less sensitive and less susceptible to false alarms methods.
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Craft, Jennifer Lorraine. "Reducing Drifts in Buckling Restrained Braced FramesThrough Elastic Stories." BYU ScholarsArchive, 2015. https://scholarsarchive.byu.edu/etd/4430.
Full textAbstract:
It is possible to reduce residual and maximum drifts in buildings by adding “elastic stories” that engage gravity columns in seismic response. An elastic story is a story wherein the buckling restrained brace frame (BRBF) size is increased to prevent yielding when an earthquake occurs. Buildings ranging from 4–16 stories were designed with various elastic story brace sizes and locations to determine the optimal combination to best reduce drifts. Gravity column stiffnesses were also varied in elastic story buildings to determine the effects on drifts. Computer models were used to analyze these buildings under a suite of earthquakes. Adding elastic stories reduce residual drifts 34% to 65% in 4- to 16-story BRBF buildings. General recommendations are made to achieve optimal reductions in drifts. For buildings with six or more stories, drifts were generally reduced most when an elastic story was added to every 4th story starting at level 1 (the bottom story). The most effective size for the braces in the elastic story appears to be three times the original brace size. For buildings with less than six stories, adding a three times elastic story to the bottom level was observed to reduce drifts the most. Further research is also recommended to confirm the optimal location and size of elastic stories for buildings with differing number of stories. Increasing gravity column stiffnesses in buildings with elastic stories helps to further reduce drifts, however it may not be economical. Residual drifts were observed to decrease significantly more than maximum drifts when elastic stories were added to buildings. Maximum drifts generally decreased at some levels, but also increased at others when elastic stories were used.
29
Svartz, S:t Cyr Daniel, and Lars Einar Enarsson. "Framtidens driftcentral : En analys av den framtida driften av ett svenskt elnät." Thesis, Uppsala universitet, Fasta tillståndets fysik, 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-207381.
Full textAbstract:
Active work to increase the efficiency of energy use is taking place in Sweden and throughout all of Europe. Electricity is an important part in our society’s energy system which means that the electrical grid operators and associated therewith has a central role in this work. Monitoring and controlling the electrical grids are managed from the distribution system operator’s DC, dispatch center. The aim of this report is to examine how the operations in a typical DC on the Swedish electricity distribution network will look like in five to ten years. The report focuses on DC’s that operate electrical grids at low- and medium voltage level. For a concrete way to determine how the DC will change over time the different operational processes that constitute the ope- ration of a DC were defined. Subsequently the changes that will affect the Swedish electrical grids within five to ten years were investigated and also in which way these changes will implicate the operational processes in a DC. The analysis shows that the DC’s will undergo a series of transformations in five to ten years. By integrating the various IT-systems in the dispatch center the main operation will be manageable from a single HMI, such as a DMS-system. This means that business processes such as monitoring, ope- rational order processing and error handling will be possible from a single system in the future. But the increasing communication between IT systems will also lead to increased demands for security because any intrusion in one of the systems could result in major damage.
30
Wattimena, Ridho K. "Designing undercut and production level drifts of block caving mines /." [St. Lucia, Qld.], 2003. http://www.library.uq.edu.au/pdfserve.php?image=thesisabs/absthe17451.pdf.
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Dubazane, Makhosonke Berthwell. "Modelling Ionospheric vertical drifts over the African low latitude region." Thesis, Rhodes University, 2018. http://hdl.handle.net/10962/63356.
Full textAbstract:
Low/equatorial latitudes vertical plasma drifts and electric fields govern the formation and changes of ionospheric density structures which affect space-based systems such as communications, navigation and positioning. Dynamical and electrodynamical processes play important roles in plasma distribution at different altitudes. Because of the high variability of E × B drift in low latitude regions, coupled with various processes that sometimes originate from high latitudes especially during geomagnetic storm conditions, it is challenging to develop accurate vertical drift models. This is despite the fact that there are very few instruments dedicated to provide electric field and hence E × B drift data in low/equatorial latitude regions. To this effect, there exists no ground-based instrument for direct measurements of E×B drift data in the African sector. This study presents the first time investigation aimed at modelling the long-term variability of low latitude vertical E × B drift over the African sector using a combination of Communication and Navigation Outage Forecasting Systems (C/NOFS) and ground-based magnetometer observations/measurements during 2008-2013. Because the approach is based on the estimation of equatorial electrojet from ground-based magnetometer observations, the developed models are only valid for local daytime. Three modelling techniques have been considered. The application of Empirical Orthogonal Functions and partial least squares has been performed on vertical E × B drift modelling for the first time. The artificial neural networks that have the advantage of learning underlying changes between a set of inputs and known output were also used in vertical E × B drift modelling. Due to lack of E×B drift data over the African sector, the developed models were validated using satellite data and the climatological Scherliess-Fejer model incorporated within the International Reference Ionosphere model. Maximum correlation coefficient of ∼ 0.8 was achieved when validating the developed models with C/NOFS E × B drift observations that were not used in any model development. For most of the time, the climatological model overestimates the local daytime vertical E × B drift velocities. The methods and approach presented in this study provide a background for constructing vertical E ×B drift databases in longitude sectors that do not have radar instrumentation. This will in turn make it possible to study day-to-day variability of vertical E×B drift and hopefully lead to the development of regional and global models that will incorporate local time information in different longitude sectors.
32
Kim, Ha Yang. "Modeling and tracking time-varying clock drifts in wireless networks." Diss., Georgia Institute of Technology, 2014. http://hdl.handle.net/1853/53988.
Full textAbstract:
Clock synchronization is one of fundamental requirements in distributed networks. However, the imperfection of crystal oscillators is a potential hurdle for network-wide collaboration and degrades the performance of cooperative applications. Since clock discrepancy among nodes is inevitable, many software and hardware attempts have been introduced to meet synchronization requirements. Most of the attempts are built on communication protocols that demand timestamp exchanges to improve synchronization accuracy or resource efficiency. However, link delay and environmental changes sometimes impede these synchronization efforts that achieve in desired accuracy.
First, the clock synchronization problem was examined in networks where nodes lack the high accuracy oscillators or programmable network interfaces some previous protocols depend on. Next, a stochastic and practical clock model was developed by using information criteria which followed the principle of Occam's razor. The model was optimized in terms of the number of parameters. Simulation by using real measurements on low-powered micro-controllers validated the derived clock model. Last, based on the model, a clock tracking algorithm was proposed to achieve high synchronization accuracy between unstable clocks. This algorithm employed the Kalman filter to track clock offset and skew. Extensive simulations demonstrated that the proposed synchronization algorithm not only could follow the clock uncertainties shown in real measurements but also was tolerant to corrupted timestamp deliveries.
Clock oscillators are vulnerable to noises and environmental changes. As a second approach, clock estimation technique that took circumstances into consideration was proposed. Through experiments on mobile devices, the obstacles were clarified in synchronization over wireless networks. While the causes of clock inaccuracy were focused on, the effect of environmental changes on clock drifting was investigated. The analysis of the observations inspired an M-estimator of clock error that was accurate but under dominant disturbances such as oscillator instability and random network delay. A Kalman filter was designed to compensate with temperature changes and estimate clock offset and skew. The proposed temperature-compensated Kalman filter achieved the better estimates of clock offset and skew by adjusting frequency shifts caused by temperature changes.
The proposed Kalman filter-based clock synchronization was implemented in C. A real-time operation was proved by clock tracking between two mobile platforms that the synchronization technique was implemented on. Moreover, the technique was converted to fixed-point algorithm, which might degrade performance, to evaluate the synchronizing operation on fixed-point processors. The fixed-point simulation reported performance degradation caused by limited hardware resources; however, it also corroborated the applicability of the synchronization technique.
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Lemon, Michael R. "Comparison of Los Alamos National Laboratory (LANL) Parallel Ocean Program (POP) model velocity fields with Pacific surface drifter measurements." Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 1997. http://handle.dtic.mil/100.2/ADA341312.
Full textAbstract:
Thesis (M.S. in Physical Oceanography) Naval Postgraduate School, September 1997.<br>"September 1997." Thesis advisor(s): Julie L. McClean, Jeffrey D. Paduan. Includes bibliographical references (p. 111-114). Also available online.
34
Okamoto, Rogerio Takao. "Desenvolvimento de método analítico rápido de cefalexia na forma pó para suspensão oral por espectroscopia no infravermelho." Universidade de São Paulo, 2014. http://www.teses.usp.br/teses/disponiveis/9/9139/tde-30042015-100551/.
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A cefalexina é um dos antibióticos mais prescritos no Brasil e a sua disponibilidade nas instituições de saúde é de extrema importância para o tratamento adequado e seguro dos pacientes. Porém a distribuição dos medicamentos é prejudicada pela dificuldade de liberação pelos laboratórios de controle de qualidade que utilizam métodos convencionais como: o biológico (Difusão em Ágar) e o cromatográfico (Cromatografia Líquida de Alta Eficiência), que demandam tempo de análise e não permitem a obtenção de resultados em tempo real. O maior desafio dos centros produtivos é desenvolver métodos capazes de realizarem as análises dos produtos de forma rápida e eficaz durante as fases mais críticas da produção. As técnicas espectroscópicas por infravermelho são alternativas aos métodos convencionais, tendo como vantagens a rapidez, a capacidade de análise de amostras nas suas formas físico-químicas originais e a possibilidade de projetar a sua utilização na Tecnologia Analítica de Processos (PAT). Com esse propósito foi desenvolvido um método por espectroscopia no infravermelho médio (MID) por reflectância difusa (DRIFTS) combinado à técnica de regressão múltipla por mínimos quadrados parciais (PLS) para análise de cefalexina na forma pó para suspensão oral. A avaliação da eficácia do método desenvolvido foi feita mediante cálculo da precisão e exatidão do método e posteriormente os resultados experimentais foram submetidos à análise estatística. A verificação da equivalência dos métodos foi feita utilizando análise de variância (ANOVA) e, para finalizar o trabalho, foi determinado o intervalo de tolerância (δ) do método. O método espectroscópico apresentou significativa variabilidade de resultados, porém uma técnica padronizada de preparo das amostras de calibração capaz de produzir misturas homogêneas do fármaco com placebo, aliado à seleção criteriosa das regiões espectrais e tratamento espectral adequado, foi determinante para o desenvolvimento de um método equivalente aos convencionais, atendendo aos requisitos da PAT. Portanto, este trabalho pode servir de ferramenta para o avanço da PAT pelos produtores e agência regulatória no Brasil (ANVISA).<br>Cephalexin is the most prescribed antibiotics in Brazil and its availability in health institutions is of utmost importance for the proper and safe treatment of patients. But the distribution of drugs is hindered to difficulty of release by quality control laboratories using conventional methods such as biological (Agar Diffusion) and HPLC (High Performance Liquid Chromatography), which require analysis time and not allow to obtain results in real time. The biggest challenge of manufacturing centers is to develop analytical methods to perform quickly and effectively analyzes of the products during the most critical phases of production. The infrared spectroscopic technique is alternative to conventional methods, with the advantages of speed, the ability to analyze samples in their original physical-chemical forms and the possibility to use in designing the Process Analytical Technology (PAT). For this purpose, a method was developed in the mid-infrared spectroscopy (MID) by diffuse reflectance (DRIFTS) combined to technique of partial least squares (PLS) regression for cephalexin analysis in oral suspension product. Assessing the effectiveness of the method was done by calculation of precision and of the method and then the experimental results were subjected to statistical analysis. The equivalence of methods was verified using analysis of variance (ANOVA) and, to complete the work, the tolerance interval (δ) was determined. The spectroscopic method showed significant variability in results, but a standardized technique for preparation of calibration samples able to produce homogeneous mixtures of the drug with placebo, combined to careful selection of spectral regions and appropriate spectral treatment, was crucial for the development of an equivalent method to conventional, meeting the requirements of PAT. Therefore, this work can serve as a tool for advancing the PAT by manufacturers and regulatory agency in Brazil (ANVISA).
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Axner, Theodor. "Uppsala universitetsbibliotek före 1694 : Grundläggande problematik kring driften av ett tidigt akademiskt bibliotek." Thesis, Uppsala University, Department of ALM, 2002. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-101571.
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Hohbein, Michael William. "Cenozoic contourite drifts and palaeoceanographic development of the Faeroe Shetland Basin." Thesis, Cardiff University, 2005. http://orca.cf.ac.uk/56039/.
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This thesis investigated the palaeoceanographic history of the Faeroe Shetland Basin, NE Atlantic, via identification and analysis of contourite drift deposits using petroleum industry seismic and well data. Integration of regional 2D seismic lines, 3D seismic volumes and high resolution seismic profiles w ith industrial well data permitted full spatial and temporal characterisation of the contourites within the basin, including identification of small scale architectural elements and subtle stratigraphic relationships. In turn, it was possible to make interpretations regarding the palaeoceanographic regime within the basin from the onset and evolution of thermohaline current flow through the basin to correlation with the present day oceanographic situation. Overall, the study serves to highlight the efficacy of industrial seismic and well data for contourite and palaeoceanographic research. A variety of contourite drift types were identified during seismic-chronostratigraphic division of the Cenozoic succession. Identification of an early middle Eocene contourite drift within the southern Faeroe Shetland Basin dates the onset of southerly flowing deep waters from the Norwegian Greenland Sea into the North Atlantic as part of a North Atlantic Conveyor Belt-style circulation system at approximately 49 million years, predating previous estimates by more than 15 million years. The presence of Oligocene, Miocene and Pliocene contourite drifts within the basin reveals that following initiation in the middle Eocene, southerly flowing deep water circulation through the basin was continuous throughout the late Palaeocene and Neogene to the present day. A gradual increase in deep water flux through the basin throughout this time is hypothesised based on contourite distribution, and is thought to relate to the global greenhouse to icehouse climatic transition that occurred during the Cenozoic. Pulses of increased deep water current velocity related to a combination of climatic and tectonic factors are thought to be responsible for the formation of major deep w ater erosional unconformities which are associated with the contourite drift successions. A link between contourite deposition and the climatic fluctuations that characterised the late Neogene northern hemisphere is also proposed based on the identification of direct indicators of significant glaciation including iceberg plough marks within the contourite drift units. Contourite drift deposition is interpreted to occur predominantly during climatically warmer episodes, while periods of glaciation are characterised by apparent disruption of ocean current circulation within the basin.
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Ling, Chengcheng [Verfasser]. "Stochastic differential equations with singular drifts and multiplicative noises / Chengcheng Ling." Bielefeld : Universitätsbibliothek Bielefeld, 2020. http://d-nb.info/1206592184/34.
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Hui, Debrup. "Altitudinal Variability of Quiet-time Plasma Drifts in the Equatorial Ionosphere." DigitalCommons@USU, 2015. https://digitalcommons.usu.edu/etd/4536.
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The plasma drifts or electric fields and their structures in the ionosphere affect the accuracy of the present-day space-based systems. For the first time, we have used ionospheric plasma drift data from Jicamarca radar measurements to study the climatology of altitudinal variations of vertical and zonal plasma drifts in low latitudes during daytime. We used data from 1998 to 2014 to derive these climatological values in bimonthly bins from 150 km to 600 km. For the vertical plasma drifts, we observed the drifts increasing with altitudes in the morning and slowly changing to drifts decreasing with altitude in the afternoon hours. The drifts change mostly linearly from E- to F-region altitudes except in the morning hours of May-June when the gradients are very small. The zonal drifts show a highly nonlinear increase in the westward drifts at the lower altitudes and then increase slowly at the higher altitudes. We see a break in the slopes at lower altitudes during the morning hours of March-April and May-June. The E-region zonal drifts, unlike vertical drifts, show a very large variability compared to F-region drifts. We also explored the altitudinal profiles of vertical drifts during late afternoon and evening hours when the electrodynamic properties in the ionosphere change rapidly. For the first time using drifts up to 2000 km, we have shown the drifts increase and decrease below and above the F-region peak before becoming height independent. These structures arise to satisfy the curl-free condition of electric fields in low latitudes. The altitudinal gradients of vertical drifts are balanced by a time derivative of the zonal drifts to satisfy the curl-free condition of electric fields. We have shown how these structures evolve with local time around the dusk sector and change with solar flux. During solar minimum, the peak region can go well below 200 km. The present-day electric field models do not incorporate these gradients, particularly in the evening sectors when they change very rapidly. Very often their results do not match with the observations. Including these gradients along with proper magnetic field models will improve the model results and accuracy of our navigation, communication, and positioning systems.
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Alves, Daniela Meyer Fernandes. "Estudo da redução do NO pelo CO usando catalisadores de ródio suportado em óxido misto de cério e zircônio e óxido misto derivado de hidrotalcita." Universidade do Estado do Rio de Janeiro, 2013. http://www.bdtd.uerj.br/tde_busca/arquivo.php?codArquivo=7776.
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Esta tese teve como objetivo avaliar o desempenho de catalisadores de Rh suportados
em cério-zircônio (CZ) e em óxido misto de magnésio e alumínio (HT) derivado de
hidrotalcita na reação de redução do NO pelo CO em meio estequiométrico. Os suportes puros
e impregnados com Rh foram nomeados CZ, RhCZ, HT e RhHT. Os suportes foram
preparados por coprecipitação e o metal nobre foi adicionado no teor de 0,15% (m/m) por
impregnação a seco. Foram realizados testes de caracterização como fisissorção de N2, DRX,
TPR, espectroscopia Raman, DRIFTS, TGA-DTA e TPD-CO/NO. Para a avaliação catalítica,
foi utilizada uma mistura de 1%NO + 1%CO em He e a atividade e seletividade foram
expressas através das concentrações dos gases envolvidos ao longo de uma rampa de
temperatura desde a temperatura ambiente até 500C. Os resultados de caracterização
indicaram nítidas diferenças estruturais e físico-químicas entre os dois tipos de catalisadores
nas isotermas de adsorção de N2, nos perfis de redução e nos difratogramas, já dando indícios
de que os mecanismos de reação seriam diferentes. Pelas análises de DRIFTS identifica-se a
presença de bandas características de espécies de CO adsorvidas no Rh somente para o
catalisador RhCZ a baixa temperatura, ressaltando a interação Rh-CZ, também evidenciadas
pelos resultados de Raman, mas que provavelmente não ocorrem com o óxido misto de Al e
Mg. Observou-se que o suporte de CZ foi mais ativo a baixas temperaturas que o suporte de
HT, porém o catalisador RhHT foi mais seletivo a N2 a 350C e emitiu menos N2O ao longo
da faixa de temperatura avaliada do que o catalisador RhCZ. Resultados de TPD de NO e
comparações de curvas experimentais e teóricas envolvendo as concentrações de CO, CO2 e
NOx durante os testes catalíticos, acompanhados também pelas análises de DRIFTS nas
mesmas condições, indicam que a redução do Rh e a afinidade do catalisador pelo NO são
importantes para favorecer a maior seletividade da reação de redução do NO pelo CO a N2.<br>The aim of this work was to evaluate the catalytic performance of cerium-zirconium
and hydrotalcite-like Mg-Al mixed oxide as supports in the reduction of NO by CO catalyzed
by rhodium. The pure supports and metallic catalysts were named CZ, RhCZ, HT and RhHT.
The supports were prepared by coprecipitation and were impregnated with 0,15% wt. of Rh.
Characterization tests such as N2 fisisorption, XRD, TPR, Raman spectroscopy, DRIFTS,
TGA-DTA and NO/CO TPD were performed. To measure the catalytic activity, a gas mixture
containing 1% NO + 1% CO in He was used. Activity and selectivity were expressed by
means of the gas concentrations measured all over a temperature range, from room
temperature to 500C. The characterization results clearly indicated structural and physicochemical
differences between the two supports in N2 adsorption isotherms, XRD and TPR
profiles and therefore, they would work through different mechanisms. DRIFTS analyses
indicated the presence of bands resulting from the adsorption of CO on Rh at low
temperatures on RhCZ catalyst, evidencing the great synergy between Rh and CZ, already
indicated by Raman results. This synergic effect probably did not occur in RhHT catalyst. The
CZ support was more active at low temperatures than HT, however, RhHT catalyst was more
selective to N2 at 350 C and emitted less N2O than RhCZ through the evaluated temperature
range.The NO TPD results and the comparison of theoretical and experimental CO, CO2 and
NOx curves during catalytic tests, also followed by DRIFTS, indicate that Rh reduction and
the affinity with NO are important parameters to achieve higher selectivity to N2 in the
reduction of NO by CO.
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Kjellsson, Joakim. "Atmospheric & Oceanic Applications of Eulerian and Lagrangian Transport Modelling." Doctoral thesis, Stockholms universitet, Meteorologiska institutionen (MISU), 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-97348.
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This thesis presents several ways to understand transports of air and water masses in the atmosphere and ocean, and the transports of energy that they imply. It presents work using various kinds of observations as well as computer simulations of the atmosphere and oceans. One of the main focuses is to identify similarities and differences between models and observations, as well as between different models. The first half of the thesis applies Lagrangian methods to study flows in the atmosphere and oceans. Part of the work focuses on understanding how particles follow the currents in the Baltic Sea and how they disperse. It is suggested that the commonly used regional ocean model for the Baltic Sea, RCO, underestimates the transport and the dispersion of the particles, which can have consequences for studies of e.g. biogeochemistry as well as for operational use. A similar methodology is used to study how particles are transported between the tropics and mid-latitudes by the large-scale atmospheric circulation. It is found that the mass transport associated with northbound and southbound particles can cancel in the zonally averaged circulation, and we propose that the degree of cancellation depends on the method of averaging. The latter half of the thesis focuses on Eulerian stream functions and specifically a thermodynamic stream function that combines the zonal and meridional circulations of the atmosphere into a single circulation. The results are used to study the inter-annual variability of the intensity and thermodynamic properties of the global atmospheric circulation. A significant correlation to ENSO variability is found both in reanalysis and the EC-Earth coupled climate model. It is also shown that a set of models from the CMIP5 project show a slowdown of the atmospheric circulation as a result of global warming and associated changes in near-surface moisture content and upper-level radiative cooling.<br>Denna avhandling presenterar olika metoder för att studera datormodeller av atmosfä- ren, haven, och klimatsystemet. Metoderna använder såväl Lagrangeska synsätt dvs att betrakta atmosfären eller haven som individuella partiklar i rörelse, som Eulerska synsätt där atmosfären och haven ses som gas eller vätska i rörelse. I artikel 1 sjö- sätts ett antal “surface drifters” i Östersjön som driver fritt med havsströmmarna och vars hastighet mäts av satelliter. Genom att modellera Lagrangeska partiklars rörelser i Östersjön och jämföra med dessa “surface drifters” kan det visas att datormodeller kan underskatta både medelhastigheten av partiklarna samt deras utbredning. I ar- tikel 2 simuleras luftmassornas rörelser mellan tropikerna och mellanbreddgraderna (∼ 45◦N/S). Ett medelvärde över all longituder tenderar att ignorera betydande mass- och energitransporter mellan tropikerna och mellanbredderna, och dessa kvantifieras i detalj i artikel 2. Artiklarna 3 och 4 presenterar en metod för att studera atmosfärens storskaliga rörelser utifrån ett termodynamiskt perspektiv där luftmassornas värme och fukt studeras. Det visas att variationer ytvattentemperatur vid ekvatorn i Stilla havet kan få atmosfären att, i ett globalt medelvärde, bli fuktigare och varmare samtidigt som masstransporter- na saktar ner. På samma sätt visas att en global uppvärmning till följd av ökade utsläpp av växthusgaser kan få atmosfären att bli varmare, fuktigare och att masstransporterna kan sakta ner.<br><p>At the time of the doctoral defence the following papers were unpublished and had a status as follows: Paper 3: In press; Paper 4: Manuscript.</p><br>BalticWay
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Wallstam, Martin. "Backpacker Institutionalization : Towards an Experience-Based Typology." Thesis, Mittuniversitetet, Institutionen för samhällsvetenskap, 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:miun:diva-14631.
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Backpacking is becoming an increasingly commonplace rite of passage for today’s independent travellers. So much so that it is not only a small niche segment anymore but is turning into a sizeable market for some destinations. Backpackers seem to lead the way into unexploited regions,subsequently opening the door for other forms of tourism. In effect, the normalization ofbackpacking brings with it questions of sustainability. This thesis sets out to explore the transition of tourism segments in destinations, particularly that of backpackers into the mainstream. It does so through a participant-observer data collection in the Philippines. The material is then analysed by grounded theory and presented in an ethnography format through a thematic review. A typological framework is the product, which brings an experience perspective to existing classification systems. Findings suggest that there are indeed nuances within the seemingly homogenous backpacker segment and that a continuous change of visitor profiles within destinations seems likely. Institutionalized backpacking turns out to be the missing link that accounts for the change from purism to mass tourism. Future explorative research is then advised, to find relationships between visitor types and to construe concrete suggestions for likely causes to the observed categorical transitions.
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Nilsson, Håkan, and Andreas Tuvesson. "Mobilitet, abstraktioner och kontextmedvetenhet:Nya vägar för SRÖ i Karlskrona att övervaka driften av fastigheter." Thesis, Blekinge Tekniska Högskola, Sektionen för teknokultur, humaniora och samhällsbyggnad, 2004. http://urn.kb.se/resolve?urn=urn:nbn:se:bth-1717.
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Denna magisteruppsats beskriver framtagande och utveckling av riktlinjer för ett system vars mål är att förändra och förbättra en organisation, där arbetet idag utgår ifrån en stationär plats men där vi hävdar att arbetssättet skulle kunna vara helt mobilt. I uppsatsen beskriver och diskuterar vi vårt tillvägagångssätt, resultatet av fältstudier och analys samt en diskussion som behandlar konstruktionen av ett mobilt anpassningsbart system. Uppsatsen resulterar i framtagandet av designriktlinjer för en mobil artefakt. Denna artefakt ska kunna stödja det arbete som utförs av personalen som arbetar med drift och övervakning av fastigheter i Karlskrona kommun. Artefakten ska vara anpassningsbar till den miljö som den används inom, den ska ha förmågan att känna av den kontext den opererar inom samt ha förmågan att följa de interaktioner som personalen utför. Utifrån våra designidéer stödjs användaren av anpassningsbara abstraktionsnivåer och öppen implementation.<br>This master thesis describes the development and creation of guidelines for a computer based system, where the goal is to change and improve an organization. Today the organization works from a stationary place but we argue that their way of doing their work could be mobile. In this thesis we describe and discuss our progress procedure, field study and the analysis. The thesis results in a creation of design guidelines for a adaptable mobile artifact. This artifact should be used by the staff who works with maintenance and surveillance of buildings in the municipality of Karlskrona. The artifact should be adaptable to the settings in which it is used. It must have the ability to be aware of its own context and it shall support the interactions that are done by the users. On the basis of our design ideas the user should be supported by adaptable abstractions and open implementation.
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Zhang, Yu. "Valorisation catalytique de produits oxygénés issue des biorafinneries de lingo-cellulose." Thesis, Lyon, 2017. http://www.theses.fr/2017LYSE1013.
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Cette thèse porte sur l'hydrogénation en phase gazeuse du furfural sur des oxydes de fer et de magnésium. De nombreux catalyseurs avec différents ratio molaires en fer et magnésium ont été préparés par des méthodes de co-précipitation ou d'imprégnation. Ils ont été ensuite testés lors de la réduction du furfural (FU) en utilisant du méthanol comme donneur d'hydrogène. L'alcool furfurylique (FAL) et le 2-methyl furfural (MFU) étaient les principaux produits obtenus démontrant alors que les systèmes Mg/Fe/O peuvent favoriser les réactions d'hydrogénation séquentielles et d'hydrogénolyse. Les catalyseurs imprégnés se sont révélés plus actif et sélectif vis-à-vis des MFU que ceux préparés par co-précipitation. Les données rapportées ont montré que la distribution du produit était fortement influencée par la teneur en fer et par l'acide résultant, ainsi que les propriétés d'oxydoréduction du matériau. En effet, l'introduction de fer à la surface d'oxyde basique a conduit à l'addition d'acidité de Lewis et de potentiel d'oxydoréduction dans le système, améliorant significativement la conversion de FU et la production de MFU. L'activation des différentes espèces à la surface du catalyseur a été étudié in-situ par DRIFTS et FTIR. Les résultats révèlent que la basicité du MgO favorise l'activation du méthanol et que le potentiel d'oxydoréduction du FeOx pourrait être responsable de l'hydrogénolyse de l'alcool furfurylique<br>This PhD project is focused on the gas phase hydrogenation of furfural over iron and magnesium oxides. Numerous catalysts with different iron and magnesium molar ratios, were prepared by co-precipitation or impregnation methods and were tested for the reduction of furfural (FU) using methanol as hydrogen donor. Furfuryl alcohol (FAL) and 2-methyl furfural (MFU) were the main products obtained, demonstrating that Mg/Fe/O systems can promote sequential hydrogenation and hydrogenolysis reactions. Impregnated catalysts demonstrated to be more active and selective towards MFU than co-precipitated ones. Reported data demonstrated that product distribution was strongly influenced by the iron content and from the resulting acid and redox properties of the material. As a matter of fact, the introduction of iron on the surface of the basic oxide led to the addition of Lewis acidity and redox capacity in the system, significantly enhancing FU conversion and MFU production. The activation of different species on the catalyst surface has been studied by in situ DRIFTS and FTIR. The results reveal that the MgO basicity favors methanol activation and FeOx redox capacity might be the responsible of furfuryl alcohol hydrogenolysis
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Reinhardt, Helge Mark. "DRIFTS-Untersuchungen heterogener Reaktionen atmosphärisch relevanter Spurengase auf Eis- und Säurehydrat-Oberflächen." [S.l. : s.n.], 2001. http://deposit.ddb.de/cgi-bin/dokserv?idn=964604809.
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Drochner, Alfons. "Eine DRIFTS- und TP-Reaktions-Studie über die silberkatalysierte Direktoxidation von Ethen." [S.l. : s.n.], 2002. http://elib.tu-darmstadt.de/diss/000340.
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Anguiano, Bethany J. "The P-delta effects on the story drifts of steel moment frames /." Available to subscribers only, 2008. http://proquest.umi.com/pqdweb?did=1559856671&sid=8&Fmt=2&clientId=1509&RQT=309&VName=PQD.
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Amblard, Matthieu. "An investigation of the selective oxidation of NHâ†3 to Nâ†2 by Alâ†2Oâ†3-supported metal oxide catalysts using oxidising conditions." Thesis, University of Reading, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.299554.
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Pasma, Joakim. "ETT BIBLIOTEK UTAN BIBLIOTEKARIER : När en ideell förening tar över driften av det lokala barnbiblioteket." Thesis, Umeå universitet, Sociologiska institutionen, 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-171057.
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Syftet med den här uppsatsen är att undersöka biblioteket Kinderbücherei Bahrenfeld BüBa och sättet de bedriver sin verksamhet. Jag vill undersöka hur det faktum att biblioteket är föreningsdrivet med all personal på volontärbasis påverkar hur biblioteket fungerar och styrs. Den metod som jag använt för studien är kvalitativa intervjuer. Mitt fokus i studien ligger på hur arbetet fungerar och hur organisationsformen påverkar hur personalen upplever sitt arbete. Jag vill också ta reda på om Kinderbücherei Bahrenfeld BüBa lyckas väl med sitt uppdrag att bedriva biblioteksverksamhet. Syftet med studien är således att studera, beskriva och öka förståelsen för vad som utmärker ett föreningsdrivet bibliotek. Jag har fått veta mer om personalens engagemang och visioner, men också om hur de rent praktiskt, ekonomiskt och organisatoriskt bedriver sin verksamhet.
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Krauss, Kai. "Entwicklung und Einsatz einer DRIFTS-Messzelle zur In-situ-Spektroskopie heterogen katalysierter Gasphasenoxidationen." [S.l. : s.n.], 2000. http://deposit.ddb.de/cgi-bin/dokserv?idn=960529233.
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Roelly, Sylvie, and Michèle Thieullen. "Duality formula for the bridges of a Brownian diffusion : application to gradient drifts." Universität Potsdam, 2005. http://opus.kobv.de/ubp/volltexte/2006/671/.
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In this paper, we consider families of time Markov fields (or reciprocal classes) which have the same bridges as a Brownian diffusion. We characterize each class as the set of solutions of an integration by parts formula on the space of continuous paths C[0; 1]; R-d) Our techniques provide a characterization of gradient diffusions by a duality formula and, in case of reversibility, a generalization of a result of Kolmogorov.