Tikab Strukturmekanik AB, (Tikab), ett teknikkonsultföretag, har utvecklat en systemhandling för en ny sluss till ”nya Slussen” i Stockholm på uppdrag av Stockholm stad, Exploateringskontoret. En del i projektet var att även skapa attraktiva bonusfunktioner till anläggningen. Innan detta projekt startades hade Tikab visat att den konstruerade segmentluckan kunde användas för att skapa stående vågor nedströms luckan. Dessa vågor ansågs vara intressanta för vågsurfing.Målet med detta examensarbete var att utveckla en konstruktion utan rörliga delar som skulle kunna förbättra vågparametrar hos den, med avseende på surfing attraktiva, genererade vågen. Konstruktionen, också kallad vingen eller spoilern, skulle vara manuellt hanterbar och enkel att montera på slussluckan.Denna rapport beskriver utvecklingsprojektet. Efter att studerat slussen och existerande artificiella surfvågor kunde en omfattande studie av flödesteori göras. Därefter kunde teorier för flöde och vågor användas i modellförsök där de verifierades hydrodynamiskt. Spoilerkoncept togs fram och testades innan en slutlig design kunde väljas genom utvärdering av testresultaten. Det vinnande konceptet konstruerades i full skala och dimensionerades i enlighet med gällande eurokoder. Den slutgiltiga systemkonstruktionen utgjordes av en vinge uppbyggd av sex delar. De kan tillverkas av bockad aluminiumplåt med påsvetsade avstyvningar och ansluts med skruvförband till segmentluckans krön. Genom successiva optimeringar i konstruktionen kunde den totala vikten till slut reduceras till 138 kg, med en maximal vikt på 29 kg för den största delen.Vissa slutsatser drogs utifrån resultaten; Vågformen nedströms en, under vatten, nedsänkt segmentlucka kunde kontrolleras med hjälp av en skruvansluten vinge monterad på luckans krön. Därigenom kunde en attraktiv surfvåg skapas. Den bästa vågförbättringen, med avseende på surfing, uppnåddes för en horisontellt riktad vinge. Vingens form skulle för bästa inverkan vara likformad med den önskade krökningen på vågkrönet. En hanterbar och styv vinge kunde konstrueras med hjälp av aluminiumplåt och en optimerad dimensionering. / Tikab Strukturmekanik AB (Tikab), an engineering consulting company, has developed a system design of a new navigation lock at Slussen in central Stockholm on behalf of Stockholm City authorities. A part of the project has been to add attractive bonus functions to the area. It was shown by Tikab that the designed segment gate, also referred to as Tainter gate, could be used to create stationary back water waves. These waves were found to be of interest for wave surfing.The aim of this master project was to develop a device without moving parts which could improve the wave parameters into an, with respect to surfing, attractive wave. The device, also referred as spoiler, was requested to be manually manageable and easy to mount on the segment gate crest. This master thesis describes the development project. After a study of the navigation lock and existing artificial surf-wave techniques an extensive investigation of flow theory was done. From there theories for flow and wave creation could be transferred into model tests where hydrodynamic verifications were done. Spoiler concepts were developed and tested before a final design was selected by evaluation of the test results. The winning concept was designed in full-scale and dimensioned according to current Eurocodes.The final design was a spoiler which was built up by six parts. They were made for manufacturing using bent and stiffened aluminium plates and to be fastened on the gate crest by bolted joints. Through successive design optimisation, the total weight was reduced to a total of 138 kg. The weight of the largest part was 29 kg.Some conclusions were drawn from the results; The wave shape downstream a submerged segment gate could be controlled by a spoiler on the gate crest. Thereby an attractive wave could be generated. The best wave improvement, with respect to surfing, was reached for a horizontally positioned spoiler cut in a shape equal to the wished wave crest curvature. A manageable and functional spoiler could be designed by the use of aluminium plates and an optimised design.

A smart phone camera based indoor guidance system to aid the visually impaired is presented. Most proposed systems for aiding the visually impaired with indoor navigation are not feasible for widespread use due to cost, usability, or portability. We use a smart phone vision based system to create an indoor guidance system that is simple, accessible, inexpensive, and discrete to aid the visually impaired to navigate unfamiliar environments such as public buildings. The system consists of a smart phone and a server. The smart phone transmits pictures of the user's location to the server. The server processes the images and matches them to a database of stored images of the building. After matching features, the location and orientation of the person is calculated using 3D location correspondence data stored for features of each image. Positional information is then transmitted back to the smart phone and communicated to the user via text-to-speech. This thesis focuses on developing the vision technology for this unique application rather than building the complete system. Experimental results demonstrate the ability of the system to quickly and accurately determine the pose of the user in a university building.

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Stereopsis or Stereo vision is a technique that has been extensively used in computer vision these days helps to percept the 3D structure and distance of a scene from two images taken at different viewpoints, precisely the same way a human being visualizes anything using both eyes. The research involves object matching by extracting features from images and includes some preliminary tasks like camera calibration, correspondence and reconstruction of images taken by a stereo vision unit and 3D construction of an object. The main goal of this research work is to estimate the position and the orientation of a front loader bucket of an autonomous mobile robot configured in a work machine name 'Avant', which consists a stereo vision unit and several other sensors and is designed for outdoor operations like excavation. Several image features finding algorithms, including the most prominent two, SIFT and SURF has been considered for the image matching and object recognition. Both algorithms find interest points in an image in different ways which apparently accelerates the feature extraction procedure, but still the time requires for matching in both cases is left as an important issue to be resolved. As the machine requires to do some loading and unloading tasks, dust and other particles could be a major obstacle for recognizing the bucket at workspace, also it has been observed that the hydraulic arm and other equipment comes inside the FOV of the cameras which also makes the task much challenging. The concept of using markers has been considered as a solution to these problems. Moreover, the outdoor environment is very different from indoor environment and object matching is far more challenging due to some factors like light, shadows, environment, etc. that change the features inside a scene very rapidly. Although the work focuses on position and orientation estimation, optimum utilization of stereo vision like environment perception or ground modeling can be an interesting avenue of future research / <p>Validerat; 20101230 (ysko)</p>

This paper presents a new approach to the feature-matching problem for 3D reconstruction by taking advantage of GPS and IMU data, along with a prior calibrated stereo camera system. It is expected that pose estimates and calibration can be used to increase feature matching speed and accuracy. Given pose estimates of cameras and extracted features from images, the algorithm first enumerates feature matches based on stereo projection constraints in 2D and then backprojects them to 3D. Then, a grid search algorithm over potential camera poses is proposed to match the 3D features and find the largest group of 3D feature matches between pairs of stereo frames. This approach will provide pose accuracy to within the space that each grid region covers. Further refinement of relative camera poses is performed with an iteratively re-weighted least squares (IRLS) method in order to reject outliers in the 3D matches. The algorithm is shown to be capable of running in real-time correctly, where the majority of processing time is taken by feature extraction and description. The method is shown to outperform standard open source software for reconstruction from imagery. / Master of Science

In this dissertation, the extended Melnikov's method has been applied to several nonlinear ship dynamics models, which are related to the new generation of stability criteria in the International Maritime Organization (IMO). The advantage of this extended Melnikov's method is it overcomes the limitation of small damping that is intrinsic to the implementation of the standard Melnikov's method. The extended Melnikv's method is first applied to two published roll motion models. One is a simple roll model with nonlinear damping and cubic restoring moment. The other is a model with a biased restoring moment. Numerical simulations are investigated for both models. The effectiveness and accuracy of the extended Melnikov's method is demonstrated. Then this method is used to predict more accurately the threshold of global surf-riding for a ship operating in steep following seas. A reference ITTC ship is used here by way of example and the result is compared to that obtained from previously published standard analysis as well as numerical simulations. Because the primary drawback of the extended Melnikov's method is the inability to arrive at a closed form equation, a 'best fit'approximation is given for the extended Melnikov numerically predicted result. The extended Melnikov's method for slowly varying system is applied to a roll-heave-sway coupled ship model. The Melnikov's functions are calculated based on a fishing boat model. And the results are compared with those from standard Melnikov's method. This work is a preliminary research on the application of Melnikov's method to multi-degree-of-freedom ship dynamics. In the last part of the dissertation, the method of manufactured solution is applied to systems with chaotic behavior. The purpose is to identify points with potential numerical discrepancies, and to improve computational efficiency. The numerical discrepancies may be due to the selection of error tolerances, precisions, etc. Two classical chaotic models and two ship capsize models are examined. The current approach overlaps entrainment in chaotic control theory. Here entrainment means two dynamical systems have the same period, phase and amplitude. The convergent region from control theory is used to give a rough guideline on identifying numerical discrepancies for the classical chaotic models. The effectiveness of this method in improving computational efficiency is demonstrated for the ship capsize models. / Ph. D.

La vidéosurveillance a pour objectif principal de protéger les personnes et les biens en détectant tout comportement anormal. Ceci ne serait possible sans la détection de mouvement dans l’image. Ce processus complexe se base le plus souvent sur une opération de soustraction de l’arrière-plan statique d’une scène sur l’image. Mais il se trouve qu’en vidéosurveillance, des caméras sont souvent en mouvement, engendrant ainsi, un changement significatif de l’arrière-plan; la soustraction de l’arrière-plan devient alors problématique. Nous proposons dans ce travail, une méthode de détection de mouvement et particulièrement de chutes qui s’affranchit de la soustraction de l’arrière-plan et exploite la rotation de la caméra dans la détection du mouvement en utilisant le calcul homographique. Nos résultats sur des données synthétiques et réelles démontrent la faisabilité de cette approche. / The main objective of video surveillance is to protect persons and property by detecting any abnormal behavior. This is not possible without detecting motion in the image. This process is often based on the concept of subtraction of the scene background. However in video tracking, the cameras are themselves often in motion, causing a significant change of the background. So, background subtraction techniques become problematic. We propose in this work a motion detection approach, with the example application of fall detection. This approach is free of background subtraction for a rotating surveillance camera. The method uses the camera rotation to detect motion by using homographic calculation. Our results on synthetic and real video sequences demonstrate the feasibility of this approach.

Esta tesis presenta el primer estudio científico acerca de la ocurrencia de condiciones favorables para el surf en las escalas global y regional (en este caso en el Mar Cantábrico). Para ello han sido empleadas bases de datos de reanálisis atmosféricos y de oleaje previamente calibrados, los cuales permiten estimar la calidad de las condiciones y la consistencia (días de buenas condiciones de surf) la cual es la principal característica en la disponibilidad de recurso (Lazarow et al., 2007). Los valores medios obtenidos muestran una alta relación con el patrón general de circulación atmosférica y con las características de propagación de los oleajes tipo swell y, por lo tanto, con las variaciones estacionales de los mismos. El estudio de la variabilidad estacional ha sido investigado relacionando la consistencia mensual con diferentes índices climáticos como el SOI (Southern Oscillation Index) o la NAO (North Atlantic Oscillation) entre otros, mostrando valores altos de correlación. El análisis de las tendencias en el largo plazo muestra un incremento generalizado en las costas con orientación oeste (ej. 20 horas/año en California), lo cual coincide con un incremento de la actividad extratropical durante el periodo de tiempo analizado. En la escala regional han sido empleadas técnicas de regionalización para obtener campos de oleaje y viento de alta resolución con el objetivo de mejorar la estima de la calidad de las condiciones de surf. Para ello, han sido calculadas la dispersión frecuencial y direccional del espectro de oleaje mejorando la estima actual de la calidad, la cual es altamente dependiente de los procesos de propagación del oleaje por aguas someras. La variabilidad climática en esta escala ha sido estudiada por medio de técnicas de clasificación de la atmósfera que permiten obtener patrones preferenciales de variabilidad en diferentes escalas temporales: tipos de tiempo (3 días) y patrones climáticos (1 mes). Estas técnicas permiten relacionar unívocamente un estado de la atmosfera con una distribución específica de la energía del oleaje en el dominio de las frecuencias y direcciones. Esta metodología permite además analizar la variabilidad en la forma espectral debida al cambio climático o la variabilidad climática natural. / This thesis presents the firs scientific study of the surf conditions occurrence at a global and a regional scale (herein Cantabrian Sea). Calibrated wave and wind hindcast data bases have used as the ground true estimating surf quality and consistency (days of good surfing conditions) which is the most striking feature in surf resource availability (Lazarow et al., 2007). Mean consistency values are calculated finding spatial patterns highly related with the general circulation scheme and swell traveling properties and thus seasonality. Controls of inter-annual variability are investigated by comparing occurrence values with global and regional climate patterns. Southern Oscillation Index (SOI), North Atlantic Oscillation (NAO) between others, have been related to surf occurrence, showing a great influence at both, global and regional scales. Analysis of long term trends shows an increase in the probability of surfable events over the west facing coasts on the planet (e.g. 20 hours/year in California coasts), according with previous studies which indicate increased extra-tropical storminess during the past few years. Moreover, downscaling techniques have been employed obtaining high resolution wave and wind fields in order to asses surf quality in a regional scale. At this scale, spectral directional and frequency spreading have been also determined improving the current estimation of the surf quality, which is highly related to the wave shallow water processes. Clustering statistics techniques have been applied to sea level pressure over the North Atlantic obtaining leading patterns of weather (3 days) and climate variability (1 month) corresponding to AO (Arctic Oscillation), NAO or EA (East Atlantic Oscillation) atmospheric states. These techniques allow univocal relating some specific state of the atmosphere with one wave energy distribution through frequencies and directions domain, including high frequency energy coming from local winds. In addition the proposed methodology makes possible analyzing spectral variability due to climate change or natural climatic variability.

La vidéosurveillance a pour objectif principal de protéger les personnes et les biens en détectant tout comportement anormal. Ceci ne serait possible sans la détection de mouvement dans l’image. Ce processus complexe se base le plus souvent sur une opération de soustraction de l’arrière-plan statique d’une scène sur l’image. Mais il se trouve qu’en vidéosurveillance, des caméras sont souvent en mouvement, engendrant ainsi, un changement significatif de l’arrière-plan; la soustraction de l’arrière-plan devient alors problématique. Nous proposons dans ce travail, une méthode de détection de mouvement et particulièrement de chutes qui s’affranchit de la soustraction de l’arrière-plan et exploite la rotation de la caméra dans la détection du mouvement en utilisant le calcul homographique. Nos résultats sur des données synthétiques et réelles démontrent la faisabilité de cette approche. / The main objective of video surveillance is to protect persons and property by detecting any abnormal behavior. This is not possible without detecting motion in the image. This process is often based on the concept of subtraction of the scene background. However in video tracking, the cameras are themselves often in motion, causing a significant change of the background. So, background subtraction techniques become problematic. We propose in this work a motion detection approach, with the example application of fall detection. This approach is free of background subtraction for a rotating surveillance camera. The method uses the camera rotation to detect motion by using homographic calculation. Our results on synthetic and real video sequences demonstrate the feasibility of this approach.