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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.
11

Efficient driving of CBTC ATO operated trains

Carvajal Carreño, William January 2017 (has links)
Energy consumption reduction is one of the priorities of metro operators, due to financial cost and environmental impact. The new signalling system Communications-Based Train Control (CBTC) is being installed in new and upgraded metro lines to increase transportation capacity. But its continuous communication feature also permits to improve the energy performance of traffic operation, by updating the control command of the Automatic Train Operation (ATO) system at any point of the route. The present research addresses two main topics. The first is the design of efficient CBTC speed profiles for undisturbed train trajectory between two stations. The second takes into account the interaction between two consecutive trains under abnormal traffic conditions and proposes a tracking algorithm to save energy. In the first part of the research an off-line methodology to design optimal speed profiles for CBTC-ATO controlled trains is proposed. The methodology is based on a new multi-objective optimisation algorithm named NSGA-II-F, which is used to design speed profiles in such a way that can cover all the possible efficient solutions in a pseudo-Pareto front. The pseudo–Pareto front is built by using dominated solutions to make available a complete set of feasible situations in a driving scenario. The uncertainty in the passenger load is modelled as a fuzzy parameter. Each of the resulting speed profiles is obtained as a set of parameters that can be sent to the ATO equipment to perform the driving during the operation. The proposed optimisation algorithm makes use of detailed simulation of the train motion. Therefore, a simulator of the train motion has been developed, including detailed model of the specific ATO equipment, the ATP constraints, the traction equipment, the train dynamics and the track. A subsequent analysis considers the effect in the design of considering the regenerative energy flow between the train and the surrounding railway system. The second part of the research is focused on the proposal and validation of a fuzzy tracking algorithm for controlling the motion of two consecutive trains during disturbed conditions. A disturbed condition is understood as a change in the nominal driving command of a leading train and its consequences in the subsequent trains. When a train runs close enough to the preceding one, a tracking algorithm is triggered to control the distance between both trains. The following train receives the LMA (limit of movement authority) via radio, which is updated periodically as the preceding train runs. The aim of the proposed algorithm is to take actions in such a way that the following train could track the leading train meeting the safety requirements and applying an energy saving driving technique (coasting command). The uncertainty in the variations of the speed of the preceding train is modelled as a fuzzy quantity. The proposed algorithm is based on the application of coasting commands when possible, substituting traction/braking cycles by traction/coasting cycles, and hence saving energy. Both algorithms were tested and validated by using a detailed simulation program. The NSGA-II-F algorithm provided additional energy savings when compared to fixed block distance-to-go configurations, and giving a more even distribution of the solutions. The fuzzy tracking algorithm provides energy savings with a minor impact on running times while improving comfort, because of the reduction of the inefficient traction/braking cycles. / <p>QC 20170216</p>
12

Vizuální detekce osob v komerčních aplikacích / Human detection in commercial applications

Černín, Jan January 2012 (has links)
The aim of the master thesis is to derive and implement image porcessing methods for people detection and tracking in images or videos. The overall solution was chosen as a combination of modern approaches and methods which were recently presented. The proposed algorithm is able to create trajectory of the person moving in indoor building spaces even under influence of full or partial occlusion for a short period of time. The scene of interest is surveyed by a static camera having direct view on targets. Selected methods are implemented in C# programming language based on OpenCV library. Graphical user interface was created to show the final output of algorithm.
13

Displacement i hälsenan under löpning med olika skor : Analys med hjälp av speckle tracking-algoritm / Displacement in Achilles Tendon During Running with Different Shoes : Analysis with Speckle Tracking Algorithm

Kaewkam, Natthaphong, Öberg, Joakim January 2023 (has links)
Hälsenan har en viktig roll för motoriken av underbenet samt rörelse vid gång och löpning. I och med detta sker det en stor belastning på hälsenan vid gång och löpning vilket kan leda till bristningar och skador på senan. Dessa bristningar kan ske när hälsenan deformeras i samband med fysisk aktivitet. Deformation av hälsenan är differensen mellan relativ displacement i senan och är ett viktigt koncept inom förståelsen om hälseneskadors etiologi. Syftet med detta examensarbete var att öka kunskapen om displacement i hälsenan och hur det skiljer sig vid habituell löpning med olika löparskor inklusive barfotalöpning. Vidare felsöktes en speckle tracking-algoritm som lägger grund för analysen av displacement i hälsenan. Arbetet är en utökning på ett pågående forskningssamarbete mellan KTH, GIH och KI. Det första steget i arbetet var att MATLAB-programmet för speckle tracking-algoritmen felsöktes och korrigerades. Detta gjordes genom att ändra initiala startvärden i algoritmen såsom centralfrekvensen och värdet för hastigheten av displacement i hälsenan. Efter att hastigheten valts till 2 cm/s fungerade algoritmen felfritt. Nästa steg var att exekvera programmet på den ultraljudsdata för hälsenan som tidigare samlats in från forskningssamarbetet. Algoritmen kördes för tre studiepersoner för habituell löpstil med tre olika löparskor samt barfota. Detta resulterade i att medelvärdeskurvor för ytlig och djup displacement i hälsenan kunde plottas där dess minimum- och maximumvärden kunde jämföras. Efter att differensen för minimum- och maximumvärdet för ytlig och djup displacement hade jämförts mellan samtliga löparskor samt barfota, kunde följande konstateras. Löpning med traditionella skor medförde högst djup displacement följt av skor med kolfibersula, minimalistiska skor och barfotalöpning. Den sko som medförde högst ytlig displacement var skor med kolfibersula följt av traditionella skor, minimalistiska skor samt löpning barfota. Jämförelsen har ej baserats på någon statistisk grund då endast tre studiepersoner analyserades. Detta medför en viss osäkerhet gällande vilken skotyp som medför högst respektive lägst displacement. Bortsätt från denna osäkerhet kan det konstateras att resultat från tidigare studier tyder på liknande insikter. / The Achilles tendon plays a crucial role in the motor function of the lower leg, as well as in the motion involved in walking and running. As a result, the Achilles tendon undergoes significant stress during walking and running, which can lead to tears and injuries to the tendon. These tears can occur when the Achilles tendon is deformed associated with physical activity. The deformation of the Achilles tendon is the difference between the relative displacement in the tendon and is an important concept in understanding the etiology of Achilles tendon injuries. The purpose of this thesis is to increase knowledge about the displacement in the Achilles tendon and how it differs during habitual running with different running shoes, including barefoot running. Furthermore, a speckle tracking algorithm that forms the basis for analyzing the displacement in the Achilles tendon is debugged. The work is an extension of an ongoing research collaboration between KTH, GIH, and KI. The first step in the work was to debug and correct the MATLAB program for the speckle tracking algorithm. This was done by changing initial starting values in the algorithm such as the central frequency and the value for the speed of displacement in the Achilles tendon. After choosing a speed of 2 cm/s, the algorithm worked flawlessly. The next step was to execute the program on the ultrasound data for the Achilles tendon previously collected from the research collaboration. The algorithm was run for test subjects 17, 18, and 21 for habitual running style with three different running shoes and barefoot. This resulted in mean value curves for superficial and deep displacement in the Achilles tendon being plotted, with their minimum and maximum values being compared. After comparing the difference between the minimum and maximum values of superficial and deep displacement across all running shoes as well as barefoot, the following observations were made. Running with traditional shoes caused the highest deep displacement, followed by shoes with carbon fiber soles, minimalist shoes, and barefoot running. The shoe that caused the highest superficial displacement was shoes with carbon fiber soles, followed by traditional shoes, minimalist shoes, and running barefoot. The comparison was not based on any statistical basis since only three test subjects were analyzed. This implies some uncertainty as to which type of shoe causes the highest and lowest displacement. Aside from this uncertainty, it can be noted that the results from previous studies have findings that suggest similar insights.
14

Automated Detection and Analysis of Low Latitude Nightside Equatorial Plasma Bubbles

Adkins, Vincent James 21 June 2024 (has links)
Equatorial plasma bubbles (EPBs) are large structures consisting of depleted plasma that generally form on the nightside of Earth's ionosphere along magnetic field lines in the upper thermosphere/ionosphere. While referred to as `bubbles', EPBs tend to be longer along magnetic latitudes and narrower along magnetic longitudes which are on the order of thousands and hundreds of kilometers, respectively. EPBs are a well documented occurrence with observations spanning many decades. As such, much is known about their general behavior, seasonal variation of occurrences, increasing/decreasing occurrences with increasing/decreasing solar activity, and their ability to interact and interfere with radio waves such as GPS. This dissertation expands on this understanding by focusing on the detection and tracking of EPBs in the upper thermosphere/ionosphere along equatorial to low latitudes. To do this, far ultraviolet (FUV) emission observations of the recombination of O$^+$ with electrons via the Global-Scale Observations of the Limb and Disk (GOLD) mission are analyzed. GOLD provides consistent data from geostationary orbit with the eastern region of the Americas, Atlantic, and western Africa. The optical data can be used to pick out gradients in brightness along the 135.6 nm wavelength which correlate with the location of EPBs in the nightside ionosphere. The dissertation provides a novel method to look at and analyze 2-dimensional data with inconsistent time-steps for EPB detection and tracking. During development, preprocessing of large scale (multiple years) data proved to be the largest time sync. To that end, this dissertation tests the possibility of using convolution neural networks for detection of EPBs with the end goal of reducing the amount of preprocessing necessary. Further, data from the Ionospheric Connection Explorer's (ICON's) ion velocity meter (IVM) are compared to EPBs detected via GOLD to understand how the ambient plasma around the EPBs behave. Along with the ambient plasma, zonal and meridional thermospheric winds observed by ICON's Michelson Interferometer for Global High-resolution Thermospheric Imaging (MIGHTI) instrument are analyzed in conjunction with the same EPBs to understand how winds coincident with EPBs behave. An analysis of winds before EPBs form is also done to observe the potential for both zonal and meridional winds' ability to suppress and amplify EPB formation. / Doctor of Philosophy / Equatorial plasma bubbles (EPBs) are large structures that generally form during post- sunset along Earth's magnetic equator. While referred to as `bubbles', EPBs tend to be thousands of kilometers from north to south and hundreds of kilometers from east to west and well over a thousands kilometers in altitude. EPBs are a well documented occurrence with observations spanning many decades. This includes their ability to interfere with radar and GPS. This dissertation expands on the scientific community's understanding by focusing on the detection and tracking of EPBs along the magnetic equator. To do this, observations from the NASA Global-Scale Observations of the Limb and Disk (GOLD) mission are analyzed. GOLD provides consistent observations looking over the eastern region of the Americas, Atlantic, and western Africa. A unique method to look at and analyze this data for EPB detection and tracking is developed. This dissertation also tests the possibility of using machine learning for detection of EPBs. Further, data from the NASA Ionospheric Connection Explorer (ICON) mission is compared to EPBs detected via GOLD to understand how the behavior of the upper atmosphere and the conductive region therein, known as the ionosphere, interact with the EBPs themselves.
15

Quest for new nuclear magic numbers with MINOS / Quête de nouveaux nombres magiques nucléaires avec MINOS

Santamaria, Clémentine 07 September 2015 (has links)
Le détecteur MINOS a été développé jusqu'à mi-2013 pour la spectroscopie γ prompte de noyaux très exotiques à partir de réactions d’arrachage de protons. Il est composé d'une cible épaisse d'hydrogène liquide pour augmenter la luminosité et d’une chambre à projection temporelle (TPC) pour reconstruire la position du vertex de réaction et de compenser l'effet de la cible épaisse sur la correction Doppler.La chambre à projection temporelle a été développée avec l'expertise du CEA-Irfu sur les détecteurs gazeux de type Micromegas. Dans un premier temps, différentes solutions pour la TPC ont été testées dans une chambre d'essai avec une source α et des mesures de rayons cosmiques. Des muons cosmiques ont été détectés pour la première fois en utilisant la chambre d'essai en début 2013 et ont validé l'utilisation d'un plan de détection Micromegas. Le premier prototype de TPC a été achevé en mai 2013 et nous avons utilisé un banc de rayons cosmiques pour estimer l’efficacité de la TPC.MINOS a ensuite été expédié au Japon et un test de performance sous faisceau a été réalisée à l'installation médicale HIMAC (Chiba, Japon) avec deux cibles minces au lieu de la cible épaisse d'hydrogène pour valider l'algorithme de reconstruction et la résolution de la position du vertex. Un algorithme de reconstruction de traces basé sur la transformée de Hough a été mis au point pour l'analyse des données, testé avec ces données, et comparé à des simulations.La première campagne de physique avec MINOS a eu lieu en mai 2014, avec SEASTAR. Elle s’est concentrée sur la première spectroscopie des ⁶ ⁶ Cr, ⁷⁰,⁷²Fe et ⁷⁸Ni. L'analyse de la spectroscopie du ⁶ ⁶Cr a révélé deux transitions, assignées aux deux premiers états excités. Une interprétation avec des calculs de modèle en couches montre que le maximum de collectivité quadripolaire se produit à N = 40 le long de la chaîne isotopique de chrome.Le ⁶ ⁶Cr est toujours placé dans la région de l’Îlot d’Inversion à N = 40 et les calculs de modèle en couches ainsi que la comparaison avec des calculs basés sur HFB suggèrent une extension de cet Îlot d’Inversion vers N = 50 en dessous du ⁷⁸Ni. L'analyse des ⁷⁰,⁷²Fe effectuée par C. Louchart (TU Darmstadt, Allemagne) révèle la même tendance que pour les isotopes de chrome. Les données et notre interprétation par le modèle en couches suggère une grande collectivité les Cr et Fe riches en neutrons, éventuellement jusqu'à N = 50, ce qui remettrait en cause la solidité de la fermeture de couche N = 50 en dessous du ⁷⁸Ni. / The MINOS device has been developed until mid-2013 for in-beam γ spectroscopy of very exotic nuclei from proton knockout reactions. It is composed of a thick liquid hydrogen target to achieve higher luminosities and a Time Projection Chamber (TPC) to reconstruct the vertex position and compensate for the thick target effect on the Doppler correction.The Time Projection Chamber has been developed with the expertise of CEA-IRFU in gas detectors and Micromegas detectors. At first, different solutions for the TPC were tested in a test chamber with an α source and cosmic-ray measurements. Cosmic rays were detected for the first time using the test chamber in early 2013 and validated the use of a Micromegas detection plane. The first TPC prototype was finished in May 2013, and we used a cosmic-ray bench to estimate the effiiciency of the TPC. The MINOS device was then shipped to Japan and an in-beam performance test was performed at the HIMAC medical facility (Chiba, Japan) with two thin targets instead of the thick hydrogen target to validate the tracking algorithm and the vertex position resolution. A tracking algorithm for the offline analysis based on the Hough transform has been developed, tested with the data, and compared with simulations.The first physics campaign using MINOS took place in May 2014 with SEASTAR. It focused on the first spectroscopy of ⁶ ⁶ Cr, ⁷⁰,⁷²Fe, and ⁷⁸Ni. The analysis of the ⁶⁶Cr spectroscopy revealed two transitions, assigned to the two first excited states. An interpretation with shell model calculations shows that the maximum of quadrupole collectivity occurs at N=40 along the Cr isotopic chain.⁶⁶Cr is still placed in the Island of Inversion region of N=40 and the shell model calculations as well as comparison with HFB-based calculations suggest an extension of this Island of Inversion towards N=50 below ⁷⁸Ni. The analysis of ⁷⁰,⁷²Fe performed by C. Louchart (TU Darmstadt, Germany) reveals the same trend as for Cr isotopes, with a maximum of deformation at N=42. The full data set and our shell-model interpretation suggests a large collectivity for neutron-rich Cr and Fe, possibly up to N=50, questioning the robustness of the N=50 shell closure below ⁷⁸Ni.
16

Intraseasonal Variations In Sea Level Pressure And Association With Tropical Convection

Kiranmayi, L 01 July 2008 (has links)
This thesis deals with tropical intraseasonal variation (TISV) having time scales in 20-80 day range. Variations on this time scale have been observed to have profound influence on the weather and climate of the entire globe, and hence its study forms an important area of current research. A large number of studies have been carried out on this topic since the pioneering work of Madden and Julian in 1971. However, the observational studies are biased towards using the outgoing longwave radiation (OLR) as the variable of interest, and other variables, pressure in particular, have received less attention. The present thesis explores features of intraseasonal variations in sea level pressure (SLP) with the following main objectives. 1. Compare and contrast wavenumber – frequency spectra of OLR, zonal winds and SLP. 2. Quantify temporal and spatial variations of different tropical modes observed in the above variables. 3. Investigate intraseasonal variations in sea level pressure in the tropics and its meridional connections. 4. Document the movement of cloud bands during the periods of high and low TISV activity during different seasons. 5. Explore the relations between intraseasonal variations in SLP and monsoon rainfall over India. The study considered global data for a time period of 25 years from 1979 to 2003. Spectral analysis and correlations are the main tools of analysis. A combined FFT-wavelet spectral method, which uses FFT in longitude and wavelet transform in time, was developed for this purpose. This method provided an effective way of obtaining wavenumber - frequency spectra as well as in quantifying temporal variations of different modes. The transform gives spectral intensity as a function of wavenumber, frequency and time. The analysis is applied to OLR, zonal wind and SLP to understand spectral characteristics of different modes and their temporal variations. The thesis shows that the nature of spectra for OLR, SLP and wind is different although these variables are physically connected. OLR spectrum shows many of the equatorial modes observed from the previous studies for an equivalent depth of 40 m. Spectra of zonal winds at three vertical levels (850 mb, 500 mb and 200 mb) shows peaks corresponding to MJO, Kelvin modes at an equivalent depth of 75 m and Rossby Haurwitz modes. SLP spectrum is different from others. It has peaks at wavenumber zero and at MJO and Rossby Haurwitz modes. Another important new result of the thesis is the spatial and temporal behavior of SLP on intraseasonal time scales. It is shown that the the global atmosphere exhibits quasi-periodic oscillations in SLP with variations in the tropics and high latitudes strongly correlated but in opposite phases. Importantly, the strength of TISV is correlated with sea surface temperature (SST) anomalies in the equatorial Pacific Ocean. This may have some predictive value for predicting the active and weak TISV activity.
17

Fusion de données capteurs visuels et inertiels pour l'estimation de la pose d'un corps rigide / Rigid body pose estimation using fusion of inertial and visual sensor data

Seba, Ali 16 June 2015 (has links)
Cette thèse traite la problématique d'estimation de la pose (position relative et orientation) d'un corps rigide en mouvement dans l’espace 3D par fusion de données issues de capteurs inertiels et visuels. Les mesures inertielles sont fournies à partir d’une centrale inertielle composée de gyroscopes 3 axes et d’accéléromètres 3 axes. Les données visuelles sont issues d’une caméra. Celle-ci est positionnée sur le corps rigide en mouvement, elle fournit des images représentatives du champ visuel perçu. Ainsi, les mesures implicites des directions des lignes, supposées fixes dans l’espace de la scène, projetées sur le plan de l’image seront utilisées dans l’algorithme d’estimation de l’attitude. La démarche consistait d’abord à traiter le problème de la mesure issue du capteur visuel sur une longue séquence en utilisant les caractéristiques de l’image. Ainsi, un algorithme de suivi de lignes a été proposé en se basant sur les techniques de calcul du flux optique des points extraits des lignes à suivre et utilisant une approche de mise en correspondance par minimisation de la distance euclidienne. Par la suite, un observateur conçu dans l’espace SO(3) a été proposé afin d’estimer l’orientation relative du corps rigide dans la scène 3D en fusionnant les données issues de l’algorithme de suivi de lignes avec les données des gyroscopes. Le gain de l’observateur a été élaboré en utilisant un filtre de Kalman de type M.E.K.F. (Multiplicative Extended Kalman Filter). Le problème de l’ambigüité du signe dû à la mesure implicite des directions des lignes a été considéré dans la conception de cet observateur. Enfin, l’estimation de la position relative et de la vitesse absolue du corps rigide dans la scène 3D a été traitée. Deux observateurs ont été proposés : le premier est un observateur en cascade avec découplage entre l’estimation de l’attitude et l’estimation de la position. L’estimation issue de l’observateur d’attitude alimente un observateur non linéaire utilisant des mesures issues des accéléromètres afin de fournir une estimation de la position relative et de la vitesse absolue du corps rigide. Le deuxième observateur, conçu quant à lui directement dans SE(3) , utilise un filtre de Kalman de type M.E.K.F afin d’estimer la pose par fusion de données inertielles (accéléromètres, gyromètres) et des données visuelles. Les performances des méthodes proposées sont illustrées et validées par différents résultats de simulation / AbstractThis thesis addresses the problems of pose estimation of a rigid body moving in 3D space by fusing data from inertial and visual sensors. The inertial measurements are provided from an I.M.U. (Inertial Measurement Unit) composed by accelerometers and gyroscopes. Visual data are from cameras, which positioned on the moving object, provide images representative of the perceived visual field. Thus, the implicit measure directions of fixed lines in the space of the scene from their projections on the plane of the image will be used in the attitude estimation. The approach was first to address the problem of measuring visual sensors after a long sequence using the characteristics of the image. Thus, a line tracking algorithm has been proposed based on optical flow of the extracted points and line matching approach by minimizing the Euclidean distance. Thereafter, an observer in the SO(3) space has been proposed to estimate the relative orientation of the object in the 3D scene by merging the data from the proposed lines tracking algorithm with Gyro data. The observer gain was developed using a Kalman filter type M.E.K.F. (Multiplicative Extended Kalman Filter). The problem of ambiguity in the sign of the measurement directions of the lines was considered in the design of the observer. Finally, the estimation of the relative position and the absolute velocity of the rigid body in the 3D scene have been processed. Two observers were proposed: the first one is an observer cascaded with decoupled from the estimation of the attitude and position estimation. The estimation result of the attitude observer feeds a nonlinear observer using measurements from the accelerometers in order to provide an estimate of the relative position and the absolute velocity of the rigid body. The second observer, designed directly in SE (3) for simultaneously estimating the position and orientation of a rigid body in 3D scene by fusing inertial data (accelerometers, gyroscopes), and visual data using a Kalman filter (M.E.K.F.). The performance of the proposed methods are illustrated and validated by different simulation results
18

Trasování objektu v reálném čase / Visual Object Tracking in Realtime

Kratochvíla, Lukáš January 2019 (has links)
Sledování obecného objektu na zařízení s omezenými prostředky v reálném čase je obtížné. Mnoho algoritmů věnujících se této problematice již existuje. V této práci se s nimi seznámíme. Různé přístupy k této problematice jsou diskutovány včetně hlubokého učení. Představeny jsou reprezentace objektu, datasety i metriky pro vyhodnocování. Mnoho sledovacích algorimů je představeno, osm z nich je implementováno a vyhodnoceno na VOT datasetu.

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