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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
91

Apport de l’altimétrie satellitale pour l’étude de la variabilité de la circulation de surface dans le canal de Sicile et sur le plateau continental Tunisien / Contribution of satellite altimetry in the study of the surface circulation variability of the Sicilian Channel and over the Tunisian continental shelf

Jebri, Fatma 07 April 2017 (has links)
Ce travail de thèse présente une étude sur la circulation océanique de surface s'écoulantle long des talus continentaux (aux abords de l’isobathe 200 m) de la mer Méditerranée centrale. L'objectif étaitde mieux renseigner le schéma de circulation de surface dans la région et les régimes de variabilité associés ens’appuyant essentiellement sur les observations altimétriques conventionnelles (AVISO/X-TRACK) le longdes traces satellite, disponibles sur la période 1993-2015. Cette étude est également basée sur une utilisationcombinée des données spatiales de SST, de mesures in-situ hydrographiques et de courantométrieconjointement avec l'altimétrie. L'analyse a d'abord permis de caractériser la variabilité saisonnière et deproposer un nouveau schéma de circulation de surface, y compris pour les saisons intermédiaires, incluant unenouvelle branche de courant Atlantique sur le plateau continental Tunisien. Le second point fort de ce travailréside aussi dans la caractérisation du transport de surface et des modes de variations inter-annuelles de l'eauAtlantique à partir de l'altimétrie côtière sur le long terme. L‘observabilité de la méso-échelle océanique de lazone d‘étude est enfin abordée à partir des mesures altimétriques haute résolution (AltiKa). Cela a permis dedétecter des structures physiques à plus fine échelle et d'affiner le détection des variations des courants les pluscôtiers. Au delà des aspects scientifiques, cette thèse a également permis des avancées méthodologiquesimportantes concernant l’utilisation combinée de différents jeux de données spatiaux et in-situ, aisémentapplicables pour les pays du Sud. / This work presents a study on surface ocean circulation flowing along the continentalslopes (near the 200 m isobath) of the central Mediterranean Sea. The aim was to better inform the surfacecirculation patterns in the region and the associated variability regimes based mainly on along-trackconventional altimetry (AVISO / X-TRACK) available over the period 1993-2015. This study is also based onthe combined use of spatial SST data, in-situ hydrographic and current measurements in conjunction withaltimetry. The analysis has first allowed to characterize the seasonal variability and to propose a new surfacecirculation pattern, including the intermediate seasons, and a new branch of Atlantic current on the Tunisiancontinental shelf. The second highlight of this work is the characterization of surface transport and inter-annualvariations of Atlantic water from coastal altimetry over the long term. The observability of the oceanic mesoscaleof the study area is finally addressed from high resolution altimetry measurements (AltiKa). This hasallowed to detect physical structures on a smaller scale and to refine the detection of variations in the mostcoastal currents. Beyond the scientific aspects, this thesis has also allowed important methodological advancesregarding the combined use of different spatial and in-situ data sets, easily applicable for the countries of theSouth.
92

Use Of Terrain Information To Improve The Performance Of A Target Tracker

Canay, Mustafa 01 July 2009 (has links) (PDF)
Radar target tracking problem has been a popular topic for several decades. Recent works have shown that the performance of tracking algorithms increases as more prior information is used by the system / such as maximum velocity and maximum acceleration of the target, altitude of the target, or the elevation structure of the terrain. In this thesis we will focus on increasing the performance of tracking algorithms making use of benefit from the elevation model of the environment where the target tracker is searching. For a constant target altitude and a certain radar location, we generate a &ldquo / visibility map&rdquo / using the elevation model of the terrain and use this information to estimate the location and the time that the target will reappear. The second aim of this work is to use the visibility map information for improving the performance of track initiation. For that purpose, a special map has been formed, that we call as the &ldquo / track initiation probability map&rdquo / , which shows the target first time appearance density. This information has been used at the initialization part of the track initiation algorithm in order to increase the performance.
93

Quality on single-track railway lines with passenger traffic : Anlytical model for evaluation of crossing stations and partial double-tracks

Lindfeldt, Olov January 2007 (has links)
<p>Railway transportation is showing a substantial increase. Investments in new infrastructure, new fast and comfortable vehicles, and high frequency of service are important factors behind the increase.</p><p>Infrastructure configuration and timetable construction play important roles in the competitiveness of railway transportation. This is especially true on single-track lines where the travel times and other timetable related parameters are severely restricted by crossings (train meetings). The crossings also make the lines’ operation more sensitive to disturbances.</p><p>Since the major part of the Swedish railway network is single-track it is of great interest to examine the relationships between operation properties, such as travel times and reliability, and infrastructure configuration on single-track lines. The crossings are the core feature of single-track operation and this thesis focuses on the crossing time, i.e. the time loss that occurs in crossing situations.</p><p>A simplified analytical model, SAMFOST, has been developed to calculate the crossing time as a function of infrastructure configuration, vehicle properties, timetable and delays for two crossing trains. The effect of possible surrounding trains is not taken into account and all kinds of congestion effects are thus excluded from evaluation. SAMFOST has been successfully validated against the simulation tool RailSys, which shows that this type of simplified model is accurate in non-congested situations.</p><p>A great advantage of disregarding congested situations is that analysis is independent of timetable assumptions. The model also explicitly shows the effect of punctuality, which is of particular importance on single-track lines where the interdependencies between trains are strengthened by the crossings.</p><p>For the same reason, the timetable is severely constrained. Nonetheless, there is often a need for changes of the timetable (crossing pattern). The thesis proposes three simple measures of timetable flexibility, all based on assigned crossing time requirements. Together, these measures can be used to evaluate how infrastructure configuration, vehicle properties, punctuality etc affect possibilities to alter the timetable.</p><p>As an example of its application, SAMFOST has been used to evaluate the effect of shorter inter-station distance, partial double-track and combined crossing and passenger stop. These measures affect the operational properties quite differently.</p><p>More crossing stations result in a minor decrease in travel time (lower mean crossing time) but significantly higher reliability (lower crossing time variance). These effects are independent of punctuality, which is a valuable property.</p><p>A partial double-track results in shorter travel times and in some cases also higher reliability. Both effects are strongly dependent on punctuality and high punctuality is needed to achieve high effects.</p><p>A combined crossing and passenger stop results in a situation similar to that of a partial double-track. In this case it is important to point out that the assignment of time supplements in the timetable should be directly correlated to punctuality in order to achieve good operation.</p>
94

Track Persistence in Wireless Sensor Networks

Bentley, Ian 09 September 2010 (has links)
In this thesis we directly consider an object tracking problem for wireless sensor networks (WSNs), called track persistence. Track persistence temporally extends the problem of object tracking by seeking to store and retrieve the entire history of an object. To provide an initial solution to track persistence, we develop two distinct algorithms. The first algorithm, update to sink, translates track persistence into a centralized problem. The second algorithm, a linked list-like algorithm, builds a dynamic data structure as the object traverses the network, and rebuilds the object history distributively upon demand. We conduct worst case analysis upon both of these algorithms. Finally, we implement a simulation environment and run a number of tests upon both algorithms. Track persistence is a very challenging problem, and this thesis contributes a pair of solutions which stand as a basis for future research. / Thesis (Master, Computing) -- Queen's University, 2010-09-09 12:56:50.921
95

Utvärdering av patientens postoperativa smärta, illamående och informationsbehov efter införandet av en ny dagkirurgisk modell / Evaluation of the patient´s post-operative pain, nausea and information needs after the introduction of a new daysurgery model

Ekros, Helena, Lindvall, Jenny January 2014 (has links)
Introduktion: Fler och fler opereras inom den dagkirurgiska verksamheten i Sverige. För att bevara patientsäkerheten och kvaliteten i vården, bör den ständigt utvärderas och vid behov förbättras. Alternativ i detta förbättringsarbete kan vara användandet av olika dagkirurgiska fast-track modeller, där den perioperativa omvårdnaden, medicineringen och anestesimetoden anpassas efter individen och det kirurgiska ingreppet. De två vanligaste postoperativa komplikationerna patienter drabbas av efter kirurgi är smärta och illamående. Syfte med studien var att undersöka hur patienterna mådde postoperativt med fokus på smärta och illamående efter införandet av en ny dagkirurgisk fast-trackmodell. Ytterligare ett syfte var att undersöka om patienterna tyckte sig ha fått tillräckligt med information och om de hade förbättringsförslag på den perioperativa vården. Metod: Data samlades in med strukturerade postoperativa telefonintervjuer av 72 patienter. Resultatet visade att patienterna skattade sin smärta och sitt illamående lågt, de visade sig må som de hade förväntat sig postoperativt. Av studiens patienter upplevde de flesta att de hade fått tillräckligt med information i samband med den perioperativa vården. Konklusion: Resultatet i studien kan ligga till grund för vidareutveckling av den perioperativa vården. För ytterligare utvärdering av den nya dagkirurgiska fast-track modellen kan jämförande telefonintervjuer genomföras på klinikens övriga dagkirurgiska patienter. / Introduction: Day surgery is used for an increasing number of patients in Sweden. In order to preserve patient safety and quality of care, continuous evaluation and improvement is necessary. Alternatives in this improvement can be fast-track models in day surgery when tailored perioperative nursing, medication and methods of anesthesia is given to the patient. The two most common postoperative complications patients experience after surgery are pain and nausea/vomiting. Purposes: One purpose of the study was to investigate how patients were doing postoperatively, focusing on pain and nausea after the introduction of a new day surgery fast-track model. Another purpose was to investigate whether patients felt that they had received enough information and if they had suggestions for improvement in the perioperative care. Method: Data were collected using structured postoperative telephone interviews of 72 patients. Results: The result shows that the patients rated their pain and nausea as low, they felt as they had expected postoperatively. Most of the patients in the study perceived that the received information was sufficient. Conclusion: The results of the study may be the basis for further development of the perioperative care. For further evaluation of the new day surgery fast-track model, comparative telephone interviews can be conducted on this clinic’s other day surgery patients.
96

Desgastes em trilhos ferroviarios : um estudo teorico / Wear in railway tracks, a theoretical study

Semprebone, Paula da Silva 12 July 2005 (has links)
Orientador: Cassio Eduardo Lima de Paiva / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Civil, Arquitetura e Urbanismo / Made available in DSpace on 2018-08-06T06:46:08Z (GMT). No. of bitstreams: 1 Semprebone_PauladaSilva_M.pdf: 2252000 bytes, checksum: 59351d3c7428a44235337a6191251e14 (MD5) Previous issue date: 2005 / Resumo: O assunto a ser abordado nesta pesquisa refere-se ao componente da superestrutura ferroviária trilho, especificamente aos defeitos que nele se verificam em conseqüência de sua utilização como guia para o material rodante e transmissor de esforços decorrentes do movimento do veículo, e do desgaste do contato roda-trilho. A importância de se realizar este estudo fundamenta-se na necessidade de se conhecer detalhadamente os defeitos e o limite de desgaste do trilho, que permitem determinar sua vida útil, para que se possa evitar ao máximo sua substituição, devido ao alto custo envolvido, além da questão da segurança da via que, dependendo do defeito, pode ser comprometida. Para a realização do trabalho foi realizada uma pesquisa bibliográfica, objetivando reunir informações sobre o assunto e levantar dissertações existentes que buscam solucionar tais problemas. Busca-se, ainda, encontrar uma justificativa para o valor limite de desgaste adotado atualmente no meio ferroviário, que corresponde a 25% de perda em área do boleto do trilho, através de simulações do desgaste utilizando-se um modelo computacional, além de rotinas de cálculo que permitam verificar se esse parâme1rO é restrição do . ponto de vista do dimensionamento do trilho. Pretende-se, assim, a1ravés desta pesquisa proporcionar uma contribuição ao meio ferroviário, avaliando-se se o limite de desgaste adotado mos1ra-se adequado à realidade ferroviária / Abstract: The matters concerned in this research particularly refer to damages caused by stress while using tracks on permanent railways as guide and strain transmitter of the vehicles. Importance is attached to this study based on the need of understanding deep and in detail the faults and wear limits on the tracks, which allow determining its period of use, so that substitution may be avoided due to its high costs. Furthermore, the railway safety may be weaknessed depending on the sort of wear. This study has basis on a bibliographical research aiming to gather information and possible works on this field in order to solve the problems mentioned above, as well as finding proofs for the current wear rate accepted in the railway field, which is 25% of track area decrease, throughout wear simulations on a computer based model, besides calculations which allow stating whether this standard depends on the track size. This work claims to contribute to the railway field evaluating if the adopted wear rate meets our railway reality / Mestrado / Transportes / Mestre em Engenharia Civil
97

Analise parametrica da estabilidade de plataformas ferroviarias degradadas / Parametric evaluation of degraded railway subgrade stability

Aguiar, Paulo Roberto 22 August 2007 (has links)
Orientador: Cassio Eduardo Lima de Paiva / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Civil, Arquitetura e Urbanismo / Made available in DSpace on 2018-08-09T09:00:02Z (GMT). No. of bitstreams: 1 Aguiar_PauloRoberto_M.pdf: 2785267 bytes, checksum: 6bde50559dcc0d0d8052701ee543e1b3 (MD5) Previous issue date: 2007 / Resumo: O estudo desenvolvido neste trabalho consiste na avaliação da capacidade de suporte do subleito ferroviário, através da determinação do risco à ruptura circular da plataforma, de uma secção transversal de um pátio ferroviário sujeito à carga de um veículo estacionado em uma via lateral, são utilizadas as equações. Para fins de desenvolvimento do presente estudo é utilizado o método de Eisenmann para determinação das tensões atuantes na base do trilho. As tensões atuantes na plataforma são calculadas através das equações de Carothers-Terzaghi. A avaliação do risco à ruptura circular é feita através do programa computacional GEOSLOPE-SLOPE/W versão 6. Após a determinação dos fatores de segurança à ruptura para várias situações analisadas, é feita a análise dos resultados obtidos no sentido de determinar as situações de risco de estabilidade da via à ruptura circular da plataforma / Abstract: This study deals with an evaluation of subgrade capacity by determining the circular rupture stability risk of a slope adjacent to a railway yard track subject the tensions of a loaded gondola car parked in this track. The Eisenmann method is applied for determination of tensions at the railway subgrade and the tensions are calculated by means Carothers-Terzaghi equations. The analysis of circular failure risk is made by means of the computer software Geoslope-Slope/W version 6. After calculating the safety factors for many situations, the results are evaluated to stablish the stability risks of the slope adjacent to the railway track / Mestrado / Transportes / Mestre em Engenharia Civil
98

Tidig extubation efter hjärtkirurgi : graden av smärta och konfusion / Early extubation after cardiac surgery : the degree of pain and confusion

Johannesén, Helena, Thodal, Magdalena January 2010 (has links)
Bakrund: Fast track-kirurgi är ett alltmer vanligt förekommande arbetssätt inom hjärtkirurgi. Tidigare studier har påvisat att en tidig extubation har medfört en vinst i patientens rehabili-teringsprocess samt bidragit till kortare vårdtider och sänkta sjukvårdskostnader. Syfte: Syftet med studien är att kartlägga och redovisa graden av smärta och konfusion efter extubation hos patienter som genomgått hjärtkirurgi. Metod: Material inhämtades genom en fortlöpande journalgranskning. Pilotstudien granskade patientjournaler samt övervakningsjournaler i realtid. Detta utfördes i kombination med ett observationsformulär som utformats till studien innehållande mätinstrumenten VAS [Visuell Analog Skala, för smärtskattning] och RASS [The Richmond Agitation-Sedation Scale, för konfusionsbedömning]. Resultat: Patienterna upplevde smärta både efter tidig och sen extubering vid hjärtkirurgi. Efter tidig extubation dokumenterades fyra av tio patienter vara lugna och alerta samt sex av tio som slöa. Efter sen extubation dokumenterades en patient vara lätt sederad, åtta patienter slöa, en patient alert och lugn samt en patient var rastlös. Konklusion: Datamaterialet är anpassat till en pilotstudie. Således är det inte möjligt att dra några vetenskapliga slutsatser gällande korrelationen mellan extubationstid, smärta och konfusion. För att kunna uppnå en vetenskaplig signifikans krävs en studie av större kvantitet. / Background: Fast-track surgery is an increasingly common work procedure in cardiac surgery. Previous studies have shown that an early extubation has a positive effect on the patients’ reha-bilitation process and contributes to a shorter hospitalization and lowered medical costs. Purpose: The purpose of this study is to identify and recognize the degree of pain and confusion after extubation in patients’ undergone cardiac surgery. Method: Material was collected through an ongoing record review. The pilot study examined the medical records and monitoring records in real time. This was carried out in combination with an observation form designed for the study containing the instruments VAS [Visual Analogue Scale for pain measurement] and RASS [The Richmond Agitation-Sedation Scale, for the assessment of the degree of confusion]. Results: Patients experienced pain after both early and late extubation in heart surgery. After early extubation four of ten patients were documented as calm and alert, and six of ten as dull. After late extubation one patient was documented/revised to be slightly sedated, eight patients as lethargic, one patient as alert and calm, and one patient as restless. Conclusion: The data set is appropriate for a pilot study. Thus, it is not possible to draw any scientific conclusions concerning the correlation between the time of extubation, pain and confusion. In order to achieve a scientific significance, a study of greater amplitude is required.
99

Détection et poursuite en contexte Track-Before-Detect par filtrage particulaire / Detection and tracking in Track-Before-Detect context with particle filter

Lepoutre, Alexandre 05 October 2016 (has links)
Cette thèse s'intéresse à l'étude et au développement de méthodes de pistage mono et multicible en contexte Track-Before-Detect (TBD) par filtrage particulaire. Contrairement à l'approche classique qui effectue un seuillage préalable sur les données avant le pistage, l'approche TBD considère directement les données brutes afin de réaliser conjointement la détection et le pistage des différentes cibles. Il existe plusieurs solutions à ce problème, néanmoins cette thèse se restreint au cadre bayésien des Modèles de Markov Cachés pour lesquels le problème TBD peut être résolu à l'aide d'approximations particulaires. Dans un premier temps, nous nous intéressons à des méthodes particulaires monocibles existantes pour lesquels nous proposons différentes lois instrumentales permettant l'amélioration des performances en détection et estimation. Puis nous proposons une approche alternative du problème monocible fondée sur les temps d'apparition et de disparition de la cible; cette approche permet notamment un gain significatif au niveau du temps de calcul. Dans un second temps, nous nous intéressons au calcul de la vraisemblance en TBD -- nécessaire au bon fonctionnement des filtres particulaires -- rendu difficile par la présence des paramètres d'amplitudes des cibles qui sont inconnus et fluctuants au cours du temps. En particulier, nous étendons les travaux de Rutten et al. pour le calcul de la vraisemblance au modèle de fluctuations Swerling et au cas multicible. Enfin, nous traitons le problème multicible en contexte TBD. Nous montrons qu'en tenant compte de la structure particulière de la vraisemblance quand les cibles sont éloignées, il est possible de développer une solution multicible permettant d'utiliser, dans cette situation, un seule filtre par cible. Nous développons également un filtre TBD multicible complet permettant l'apparition et la disparition des cibles ainsi que les croisements. / This thesis deals with the study and the development of mono and multitarget tracking methods in a Track-Before-Detect (TBD) context with particle filters. Contrary to the classic approach that performs before the tracking stage a pre-detection and extraction step, the TBD approach directly works on raw data in order to jointly perform detection and tracking. Several solutions to this problem exist, however this thesis is restricted to the particular Hidden Markov Models considered in the Bayesian framework for which the TBD problem can be solved using particle filter approximations.Initially, we consider existing monotarget particle solutions and we propose several instrumental densities that allow to improve the performance both in detection and in estimation. Then, we propose an alternative approach of the monotarget TBD problem based on the target appearance and disappearance times. This new approach, in particular, allows to gain in terms of computational resources. Secondly, we investigate the calculation of the measurement likelihood in a TBD context -- necessary for the derivation of the particle filters -- that is difficult due to the presence of the target amplitude parameters that are unknown and fluctuate over time. In particular, we extend the work of Rutten et al. for the likelihood calculation to several Swerling models and to the multitarget case. Lastly, we consider the multitarget TBD problem. By taking advantage of the specific structure of the likelihood when targets are far apart from each other, we show that it is possible to develop a particle solution that considers only a particle filter per target. Moreover, we develop a whole multitarget TBD solution able to manage the target appearances and disappearances and also the crossing between targets.
100

3D-models of railway track for dynamic analysis.

Feng, Huan January 2011 (has links)
In recent decades, railway transport infrastructures have been regaining their importance due to their efficiency and environmentally friendly technologies. This has led to increasing train speeds, higher axle loads and more frequent train usage. These improved service provisions have however brought new challenges to traditional railway track engineering, especially to track geotechnical dynamics. These challenges demanded for a better understanding of the track dynamics. Due to the large cost and available load conditions limitation, experimental investigation is not always the best choice for the dynamic effect study of railway track structure. Comparatively speaking, an accurate mathematical modeling and numerical solution of the dynamic interaction of the track structural components reveals distinct advantage for understanding the response behavior of the track structure. The purpose of this thesis is to study the influence of design parameters on dynamic response of the railway track structure by implementing Finite Element Method (FEM). According to the complexity, different railway track systems have been simulated, including: Beam on discrete support model, Discretely support track including ballast mass model and Rail on sleeper on continuum model. The rail and sleeper have been modeled by Euler-Bernoulli beam element. Spring and dashpot has been used for the simulation of railpads and the connection between the sleeper and ballast ground. Track components have been studied separately and comparisons have been made between different models. The finite element analysis is divided into three categories: eigenvalue analysis, dynamic analysis and general static analysis. The eigenfrequencies and corresponding vibration modes were extracted from all the models. The main part of the finite element modeling involves the steady-state dynamic analysis, in which receptance functions were obtained and used as the criterion for evaluating the dynamic properties of track components. Dynamic explicit analysis has been used for the simulation of a moving load, and the train speed effect has been studied. The displacement of the trackbed has been evaluated and compared to the measurement taken in Sweden in the static analysis.

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