Global ETD Search

21	Grid-Based Focus Stacking InMicroscopic Photography : Utilizing Grid Systems For Noise Reduction Abrahamsson, William, Theo, Davnert January 2024 (has links) Microscope cameras possess high zoom capabilities and are frequently used for quality control in various industries. Visus Technology is a company that manufactures and sells these cameras, along with control software. The problem is that these cameras can only be set to one focus depth at a time. Therefore, we were tasked with implementing a fast focus stacking algorithm that combines multiple input images with different focus depths, resulting in a composite image with consistent focus throughout. This will later be integrated into the control software. We initially approached the problem by choosing pixels with the highest Laplacian intensity. This resulted in very noisy output images since the blurry images could sometimes produce high-intensity pixels where they were not supposed to be. To address this, we implemented a grid-based focus stacking algorithm. The algorithm divides the input images into tiles, filtering out the blurriest tiles to exclude them from the stacking process. The result is a composite image with significantly reduced blur. Focus stacking grid-based focus stacking noise reduction laplacian operator microscopic photography Computer Sciences Datavetenskap (datalogi) Computer Engineering Datorteknik Software Engineering Programvaruteknik
22	Scale dependence of pollinator community turnover and tritrophic interactions in changing landscapes Beduschi, Tatiane 21 July 2014 (has links) No description available. 630 grid-based landscape analysis crop rotation temporal scale spatial scale bees hoverflies landscape composition agricultural landscapes sampling biological control pest oilseed rape carry-over effects spatial dynamics biodiversity estimates Land- und Forstwirtschaft (PPN621302791)
23	利用GPS觀測量構建台灣南部地區網格式電離層模型 / A Study on Grid-Based Ionosphere Modeling of Southern Taiwan Region Using GPS Measurements 吳相忠, Wu,Shiang Chung Unknown Date (has links) 電離層延遲為精密GPS定位及導航的主要誤差來源之一，為了減弱電離層延遲對GPS定位及導航的影響，可以利用雙頻GPS觀測量構建即時的區域電離層模型，以提供即時的電離層延遲誤差改正參數，修正因電離層延遲效應造成的定位及導航誤差。本研究以台灣地區雙頻GPS觀測量，採用相位水準技術估算全電子含量（TEC）、修正的單站演算法估計各GPS衛星及接收儀之L1/L2差分延遲及以UNSW網格式演算法構建區域的電離層模型。並進而求得適合台灣南部地區網格式電離層模型之較佳網格大小及探討使用那些內政部衛星追蹤站的觀測資料，便可有效建立台灣地區的電離層模型。 / The ionospheric delay is one of the main sources of error in precise GPS positioning and navigation. The magnitude of the ionospheric delay is related to the Total Electron Content (TEC) along the radio wave path from a GPS satellite to the ground receiver. The TEC is a function of many variables, including long and short term changes in solar ionising flux, magnetic activity, season of the year, time of day, user location and viewing direction. A dual-frequency GPS receiver can eliminate (to the first order) the ionospheric delay through a linear combination of L1 and L2 observables. However, the majority of civilians use low-cost single-frequency GPS receivers that cannot use this option. Consequently, it is beneficial to estimate ionospheric delays over the region of interest, in real-time, in support of single-frequency GPS positioning and navigation applications. In order to improve real-time regional ionosphere modelling performance, a grid-based algorithm is proposed. Data from the southern Taiwan region GPS network were used to test the ionosphere modelling algorithms. From the test results described here, it is shown that the performance of real-time regional ionosphere modelling is improved significantly when the proposed algorithm is used. 電離層延遲全電子含量 L1/L2差分延遲相位水準演算法薄殼模型電離層穿透點網格式演算法 Ionospheric Delay Total Electron Content L1/L2 differential delay Phase Leveling Algorithm Thin-Shell Model Ionospheric Pierce Point Grid-Based Algorithm
24	Asteroseismic inferences from red-giant stars Themeẞl, Nathalie 28 September 2018 (has links) No description available. 530 Physik (PPN621336750) asteroseismology red-giant stars data analysis eclipsing binary system open cluster solar-like oscillations stellar interior stellar evolution photometric time series of data stellar fundamental parameters binary analysis isochrone fitting stellar modelling global oscillation parameters asteroseismic scaling relations grid-based modelling Gaia distances ground-based photometry ground-based spectroscopy Kepler space mission power density spectrum ensemble study light curve analysis
25	Lokální navigace autonomního mobilního robota / Local Navigation of an Autonomous Mobile Robot Herman, David January 2010 (has links) This paper deals with the topic of design of a navigation system for an autonomous mobile robot in a park-like environment. Precisely, designing methods for road detection using available sensoric system, designing a mathematical model for fusion of these data, and suggesting a representation of an environment suitable for planning and local navigation.
26	A Physically Based Pipeline for Real-Time Simulation and Rendering of Realistic Fire and Smoke / En fysiskt baserad rörledning för realtidssimulering och rendering av realistisk eld och rök He, Yiyang January 2018 (has links) With the rapidly growing computational power of modern computers, physically based rendering has found its way into real world applications. Real-time simulations and renderings of fire and smoke had become one major research interest in modern video game industry, and will continue being one important research direction in computer graphics. To visually recreate realistic dynamic fire and smoke is a complicated problem. Furthermore, to solve the problem requires knowledge from various areas, ranged from computer graphics and image processing to computational physics and chemistry. Even though most of the areas are well-studied separately, when combined, new challenges will emerge. This thesis focuses on three aspects of the problem, dynamic, real-time and realism, to propose a solution in form of a GPGPU pipeline, along with its implementation. Three main areas with application in the problem are discussed in detail: fluid simulation, volumetric radiance estimation and volumetric rendering. The weights are laid upon the first two areas. The results are evaluated around the three aspects, with graphical demonstrations and performance measurements. Uniform grids are used with Finite Difference (FD) discretization scheme to simplify the computation. FD schemes are easy to implement in parallel, especially with ComputeShader, which is well supported in Unity engine. The whole implementation can easily be integrated into any real-world applications in Unity or other game engines that support DirectX 11 or higher. Visualization Physically Based Pipeline Real-Time Dynamic Simulation Combustion Fire Explosion Smoke Thick Smoke Computer Graphics PDE Numerical Methods Grid Based Navier-Stokes Equation Imcompressible Fluid Radiative Transfer Equation RTE Volumetric Illumination Volumetric Rendering Volumetric Global Illumination Distant Light Source Volumetric Global Shadow Local Shadow Approximation Black-body Radiation Poisson Solver Spectroscopy Fire Color Color Reproduction Tone Mapping Color Temperature Color Matching Function Tristimulus CIE Standard Observer Color Space XYZ RGB GPU GPGPU ComputeShader DirectX 12 Unity C# Computer Sciences Datavetenskap (datalogi)
27	Vers des communications de confiance et sécurisées dans un environnement véhiculaire / Towards trusted and secure communications in a vehicular environment Tan, Heng Chuan 13 September 2017 (has links) Le routage et la gestion des clés sont les plus grands défis dans les réseaux de véhicules. Un comportement de routage inapproprié peut affecter l’efficacité des communications et affecter la livraison des applications liées à la sécurité. D’autre part, la gestion des clés, en particulier en raison de l’utilisation de la gestion des certificats PKI, peut entraîner une latence élevée, ce qui peut ne pas convenir à de nombreuses applications critiques. Pour cette raison, nous proposons deux modèles de confiance pour aider le protocole de routage à sélectionner un chemin de bout en bout sécurisé pour le transfert. Le premier modèle se concentre sur la détection de noeuds égoïstes, y compris les attaques basées sur la réputation, conçues pour compromettre la «vraie» réputation d’un noeud. Le second modèle est destiné à détecter les redirecteurs qui modifient le contenu d’un paquet avant la retransmission. Dans la gestion des clés, nous avons développé un système de gestion des clés d’authentification et de sécurité (SA-KMP) qui utilise une cryptographie symétrique pour protéger la communication, y compris l’élimination des certificats pendant la communication pour réduire les retards liés à l’infrastructure PKI. / Routing and key management are the biggest challenges in vehicular networks. Inappropriate routing behaviour may affect the effectiveness of communications and affect the delivery of safety-related applications. On the other hand, key management, especially due to the use of PKI certificate management, can lead to high latency, which may not be suitable for many time-critical applications. For this reason, we propose two trust models to assist the routing protocol in selecting a secure end-to-end path for forwarding. The first model focusses on detecting selfish nodes, including reputation-based attacks, designed to compromise the “true” reputation of a node. The second model is intended to detect forwarders that modify the contents of a packet before retransmission. In key management, we have developed a Secure and Authentication Key Management Protocol (SA-KMP) scheme that uses symmetric cryptography to protect communication, including eliminating certificates during communication to reduce PKI-related delays. Règle de combinaison de Dempster Fusion d’informations Attaques par paquets Attaques basées sur la réputation Attaques à transmission limitée VANET WMN PKI sans certificat Cryptosystèmes hybrides Proverif Accord de clé 3D basé sur un réseau Dempster’s rule of combination Information fusion Packet dropping attacks Recommendation-based trust model Reputation-based attacks Limited transmission power attacks Merkle tree authentication mechanism VANET WMN Certificate-less PKI Hybrid cryptosystems Proverif 3D grid-based key agreement

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