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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.
151

Etalonnage de caméras à champs disjoints et reconstruction 3D : Application à un robot mobile / Non-overlapping camera calibration and 3D reconstruction : Application to Vision-Based Robotics

Lébraly, Pierre 18 January 2012 (has links)
Ces travaux s’inscrivent dans le cadre du projet VIPA « Véhicule Individuel Public Autonome », au cours duquel le LASMEA et ses partenaires ont mis au point des véhicules capables de naviguer automatiquement, sans aucune infrastructure extérieure dédiée, dans des zones urbaines (parkings, zones piétonnes, aéroports). Il est doté de deux caméras, l’une à l’avant, et l’autre à l’arrière. Avant son déploiement, le véhicule doit tout d’abord être étalonné et conduit manuellement afin de reconstruire la carte d’amers visuels dans laquelle il naviguera ensuite automatiquement. Les travaux de cette thèse ont pour but de développer et de mettre en oeuvre des méthodes souples permettant d’étalonner cet ensemble de caméras dont les champs de vue sont totalement disjoints. Après une étape préalable d’étalonnage intrinsèque et un état de l’art sur les systèmes multi-caméra, nous développons et mettons en oeuvre différentes méthodes d’étalonnage extrinsèque (déterminant les poses relatives des caméras à champs de vue disjoints). La première méthode présentée utilise un miroir plan pour créer un champ de vision commun aux différentes caméras. La seconde approche consiste à manoeuvrer le véhicule pendant que chaque caméra observe une scène statique composée de cibles (dont la détection est sous-pixellique). Dans la troisième approche, nous montrons que l’étalonnage extrinsèque peut être obtenu simultanément à la reconstruction 3D (par exemple lors de la phase d’apprentissage), en utilisant des points d’intérêt comme amers visuels. Pour cela un algorithme d’ajustement de faisceaux multi-caméra a été développé avec une implémentation creuse. Enfin, nous terminons par un étalonnage déterminant l’orientation du système multi-caméra par rapport au véhicule. / My research was involved in the VIPA « Automatic Electric Vehicle for Passenger Transportation » project. During which, the LASMEA and its partnerships have developed vehicles able to navigate autonomously, without any outside dedicated infrastructure in an urban environment (parking lots, pedestrian areas, airports). Two cameras are rigidly embedded on a vehicle : one at the front, another at the back. Before being available for autonomous navigation tasks, the vehicle have to be calibrated and driven manually in order to build a visual 3D map (calibration and learning steps). Then, the vehicle will use this map to localize itself and drive autonomously. The goals of this thesis are to develop and apply user friendly methods, which calibrate this set of nonoverlapping cameras. After a first step of intrinsic calibration and a state of the art on multi-camera rigs, we develop and test several methods to extrinsically calibrate non-overlapping cameras (i.e. estimate the camera relative poses). The first method uses a planar mirror to create an overlap between views of the different cameras. The second procedure consists in manoeuvring the vehicle while each camera observes a static scene (composed of a set of targets, which are detected accurately). In a third procedure, we solve the 3D reconstruction and the extrinsic calibration problems simultaneously (the learning step can be used for that purpose) relying on visual features such as interest points. To achieve this goal a multi-camera bundle adjustment is proposed and implemented with a sparse data structures. Lastly, we present a calibration of the orientation of a multi-camera rig relative to the vehicle.
152

Volitelné aktivity v rozvrhování / Optional Activities in Scheduling

Vlk, Marek January 2021 (has links)
Scheduling allocates scarce resources to activities such that certain constraints are satisfied and specific objectives are optimized. The activities to be executed are com- monly known or determined a priori in the planning stage. To improve the flexibility of scheduling systems, the concept of optional activities was invented. Optional activities are those activities whose presence in the resulting schedule is to be decided. Rather than determining which activities need to be executed and scheduling them in two consecu- tive phases, flexibility and efficiency can be improved significantly when both activity selection and time allocation are integrated within the same solver. Such an approach was implemented in a few Constraint Programming solvers and manifested great perfor- mance on multiple scheduling problems. In this thesis, we apply the concept of optional activities to scheduling problems that do not seem to involve optional activities, such as the production scheduling problem with sequence-dependent non-overlapping setups, but also on problems beyond the scheduling domain, such as the multi-agent path finding problem and its extension with weighted and capacitated arcs. 1
153

Longevity and Economic Growth : three Essays / Longévité et croissance économique : trois essais

Brembilla, Laurent 08 November 2016 (has links)
Cette thèse s’intéresse à la relation de long-terme entre la longévité et le développement économique. Dans le premier chapitre, j’analyse l’impact des dépenses de santé sur la croissance et le bien-être. Pour cela, j’étudie l’influence du taux d’imposition dans une économie avec temps de vie endogène (Chakraborty (2004)). Je détermine le taux d’imposition qui maximise le taux de croissance. Puis je m’intéresse aux variations du niveau de production dans l’état stationnaire par rapport au taux d’imposition. Enfin, j’étudie le taux d’imposition qui maximise le bien-être dans l’état stationnaire. Dans le second chapitre, j'analyse l’impact sur la croissance de dépenses de santé choisies par les agents. En effet, je développe un modèle de croissance endogène dans lequel les individus peuvent dépenser des ressources pour vivre plus longtemps dans leur période de retraite. Je donne une caractérisation complète de l’équilibre général dynamique puis je détermine l’impact sur la croissance des dépenses de santé. Enfin, le troisième chapitre étudie l’impact théorique du vieillissement sur l’allocation sectorielle des travailleurs. Je développe un modèle multi-sectoriel dans lequel j’examine les conséquences sur le revenu par travailleur et l’allocation sectorielle des travailleurs d’un choc de longévité et de fertilité. Je montre que contrairement aux modèles uni-sectoriels, le revenu n’est pas forcément monotone par rapport aux variables démographiques. Des chocs démographiques réalistes produisent des mouvements non-négligeables de travailleurs. / This dissertation is interested in the long-run relationship between longevity and economic development. In the first chapter, I analyse the impact of health expenditures on economic growth and welfare. For this, I study the influence of the tax rate in an economy à la Chakraborty (2004). I first determine the growth-maximizing tax rate, which is shown to be 0 in low-income countries. Second, I show that the steady-state income level is an inverted U-shaped function or a decreasing function of the tax rate. Third, I study the tax rate that maximizes the steady-state welfare level. In the second chapter, I propose a theoretical model to study the growth impacts of health expenditures chosen by the agents. Indeed, I develop a Diamond model with endogenous growth in which young individuals can spend resources to increase their longevity in retirement period. I give a full characterization of the dynamic general equilibrium and determine the growth impacts of health expenditures. They can speed up or slow down economic growth. They can be a barrier or a necessity for growth to take place. A calibration to OECD countries suggests that the latter case is the most likely one. Finally, the third chapter studies the theoretical impact of the aging process on the sectorial labor allocation. To this aim, I develop a multi-sector two-period overlapping generations model in which I examine the consequences of both a longevity shift and a fertility shift on the labor allocation of the economy and on the income per worker level. I show that contrary to one-sector models, the income per worker level is not necessarily monotonic with respect to demographic variables. Realistic demographic shocks are also shown to create significant labor reallocation across sectors.
154

Investigation of Stress Transfer Behavior in Textile Reinforced Concrete with Application to Reinforcement Overlapping and Development Lengths

Azzam, Aussama, Richter, Mike January 2011 (has links)
Die kontinuumsmechanische Untersuchung der Lastübertragungsmechanismen zwischen den Rovings im textilbewehrten Feinbeton trägt wesentlich zum Gesamtverständnis des mechanischen Verhaltens des Verbundmaterials bei. Neben der Erfassung der gegenseitigen Beeinflussung sich kreuzender Rovings erfordert insbesondere die mechanische Modellierung und numerische Simulation von Bewehrungsstößen und Endverankerungen die Kenntnis dieser Übertragungsmechanismen. Die numerischen Simulationen sollen u. a. zeigen, welche Endverankerungslängen und welche Übergreifungslängen an Bewehrungsstößen erforderlich sind und wie die Querbewehrung die Rissbildung beeinflusst. / This paper concerns with the investigation of stress transfer mechanisms between yarns and concrete matrix and their influence on the overall behavior of textile reinforced concrete (TRC). This investigation considers textile reinforcement splices and textile reinforcement development lengths and carried out by means of Finite-Element simulations and fracture mechanic approaches. A first modeling procedure is made towards analyzing and investigating the damage mechanisms in TRC specimen under tension loading which are mainly characterized by matrix cracking and yarn pullout. This modeling approach allows for considering the yarn crack bridging which is a main characteristic behavior of TRC. In the same manner, 3D Finite-Element models are conducted for calculating the required reinforcement development lengths and the reinforcement overlapping lengths. The conducted approach takes into account different damage mechanisms observed in the corresponding experimental investigations which are also used for calibrating the modeling procedures. Moreover, the presented approach covers a wide range of required textile reinforcement overlapping lengths and development lengths and provides the corresponding ultimate loads.
155

Probabilistic Diagnostic Model for Handling Classifier Degradation in Machine Learning

Gustavo A. Valencia-Zapata (8082655) 04 December 2019 (has links)
Several studies point out different causes of performance degradation in supervised machine learning. Problems such as class imbalance, overlapping, small-disjuncts, noisy labels, and sparseness limit accuracy in classification algorithms. Even though a number of approaches either in the form of a methodology or an algorithm try to minimize performance degradation, they have been isolated efforts with limited scope. This research consists of three main parts: In the first part, a novel probabilistic diagnostic model based on identifying signs and symptoms of each problem is presented. Secondly, the behavior and performance of several supervised algorithms are studied when training sets have such problems. Therefore, prediction of success for treatments can be estimated across classifiers. Finally, a probabilistic sampling technique based on training set diagnosis for avoiding classifier degradation is proposed<br>
156

An improved selection algorithm for access points in wireless local area networks : An improved selection algorithm for wireless iopsys devices / En förbättrad urvalsalgoritm för accesspunkter i trådlösa lokala nätverk : En förbättrad urvalsalgoritm för trådlösa iopsys enheter

Axtelius, Mathias, Alsawadi, Rami January 2016 (has links)
Wireless devices search for access points when they want to connect to a network. A devicechooses an access point based on the received signal strength between the device and theaccess point. That method is good for staying connected in a local area network but it doesnot always offer the best performance, which can result in a slower connection. This is thestandard method of connection for wireless clients, which will be referred to as the standardprotocol. Larger networks commonly have a lot of access points in an area, which increasesthe coverage area and makes loss of signal a rare occurrence. Overlapping coverage zonesare also common, offering multiple choices for a client. The company Inteno wanted an alternativeconnection method for their gateways. The new method that was developed wouldforce the client to connect to an access point depending on the bitrate to the master, as wellas the received signal strength. These factors are affected by many different parameters.These parameters were noise, signal strength, link-rate, bandwidth usage and connectiontype. A new metric had to be introduced to make the decision process easier by unifying theavailable parameters. The new metric that was introduced is called score. A score system wascreated based on these metrics. The best suited access point would be the one with the highestscore. The developed protocol chose the gateway with the highest bitrate available, while thestandard protocol would invariably pick the closest gateway regardless. The developed protocolcould have been integrated to the standard protocol to gain the benefits of both. Thiscould not be accomplished since the information was not easily accessible on Inteno’s gatewaysand had to be neglected in this thesis. / Trådlösa enheter söker efter accesspunkt när de vill ansluta till ett nätverk. En enhet väljer enaccesspunkt beroende på den mottagna signalstyrkan mellan enheten och accesspunkten.Denna metod medför en stabil uppkoppling i ett lokalt nätverk, men medför inte alltid bästamöjliga prestanda, vilket kan resultera i en långsammare anslutning till Internet. Detta ärstandard uppkopplings metod för trådlösa klienter, vilket kommer refereras som standardprotokollen. Större nätverk har vanligtvis en mängd olika accesspunkter i ett område, vilketgör att signalstyrkan sällan förloras. Överlappande täckningsområden är också vanliga ochger en klient flera alternativa accesspunkter att välja mellan. Företaget Inteno ville tacklaproblemet genom att skapa en ny anslutningsmetod för deras nätverksnoder. Den nya metodenskulle tvinga klienter att ansluta sig till en accesspunkt beroende på bithastigheten mothuvudnoden, så väl som den mottagna signalstyrkan. Faktorerna påverkas av många olikaparametrar. Parametrarna var, brus, signalstyrka, länkhastighet, dataanvändning och anslutningstyp.Ett nytt mått behövde införas för att göra beslutsprocessen enklare, genom att förenade tillgängliga parametrarna. Det nya måttet som infördes var poäng. Ett poängsystemskapades och baserades på de önskade värdena. Den accesspunkten med högst poäng erbjödden bästa uppkopplingen till huvudnoden. Det utvecklade protokollet valde nätverksnodenmed den högsta överföringshastighet som var tillgänglig, medan standardprotokollet alltidvalde den närmaste nätverksnoden utan hänsyn till andra faktorer. Den utvecklade protokolletkunde ha integrerats med standardprotokollet för att utnyttja fördelarna av bägge protokollen.Detta var inte möjligt eftersom informationen inte var lättåtkomlig på Intenos nätverksnoderoch fick försummas i avhandlingen.
157

Combined Dermatology-Rheumatology Clinic

Csoltko, Kelly 30 March 2022 (has links)
No description available.
158

Chronic Pain as a Continuum: Autoencoder and Unsupervised Learning Methods for Archetype Clustering and Identifying Co-existing Chronic Pain Mechanisms / Chronic Pain as a Continuum: Unsupervised Learning for Identification of Co-existing Chronic Pain Mechanisms

Khan, Md Asif January 2022 (has links)
Chronic pain (CP) is a personal and economic burden that affects more than 30% of the world's population. While being the leading cause of disability, it is complicated to diagnose and manage. The optimal way to treat CP is to identify the pain mechanism or the underlying cause. The substantial overlap of the pain mechanisms (i.e., Nociceptive, Neuropathic, and Nociplastic) usually makes identification unreachable in a clinical setting where finding the dominant mechanism is complicated. Additionally, many specialists regard CP classification as a spectrum or continuum. Despite the importance, a data-driven way to identify co-existing CP mechanisms and quantification is still absent. This work successfully identified the co-existing CP mechanisms within a patient using Unsupervised Learning while quantifying them without the help of diagnosis established by the clinicians. Two different datasets from different cohorts comprised of patient-reported history and questionnaires were used in this work. Unsupervised Learning (k-prototypes) revealed notable overlaps in the data. It was further emphasized by the outcomes of the Semi-supervised Learning algorithms when the same trend was observed with some diagnosis or class information. It became evident that the CP mechanisms overlap and cannot be classified as distinct conditions. Additionally, mixed pain mechanisms do not make an individual cluster or class, and CP should be considered as a continuum. To reduce data dimension and extract hidden features, Autoencoder was used. Using an overlapping clustering technique, the pain mechanisms were identified. The pain mechanisms were also quantified while elucidating overlaps, and the dominant CP mechanism was successfully pointed out with explainable element. The hamming loss of 0.43 and average precision of 0.5 were achieved when considered as a multi-label classification problem. This work is a data-driven validation that there are significant overlaps in CP conditions, and CP should be considered a continuum where all CP mechanisms may co-exist. / Thesis / Master of Applied Science (MASc) / Chronic pain (CP) is a global burden and the primary cause for patients to seek medical attention. Despite continuous efforts in this area, CP remains clinically challenging to manage. The most effective method of treating CP is identifying the underlying cause or mechanism, which is often unattainable. This thesis attempted to identify the CP mechanisms existing in a patient while quantifying them from patient-reported history and questionnaire data. Unsupervised Learning was used to identify clinically meaningful clusters that revealed the three main CP mechanisms, i.e., Nociceptive, Neuropathic, and Nociplastic, achieving acceptable hamming loss (0.43) and average precision (0.5). The results exhibited that the CP mechanisms co-exist and CP should be regarded as a continuum rather than distinct entities. The algorithm successfully indicated the dominant CP mechanism, a goal for optimal CP management and treatment. The results were also validated by a comparative analysis with data from another cohort that demonstrated a similar trend.
159

An Optimization-Based Treatment Planner for Gamma Knife Radiosurgery

Jitprapaikulsarn, Suradet 04 March 2005 (has links)
No description available.
160

Finite Element Domain Decomposition with Second Order Transmission Conditions for Time-Harmonic Electromagnetic Problems

Rawat, Vineet 26 August 2009 (has links)
No description available.

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