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A new coefficient to characterize the global behaviour of adiabatic compressible flow at T-junctions is proposed. The new coefficient is defined according to the conclusions derived from the uncertainty propagation analysis of the total pressure loss coefficient defined by Miller for compressible flow. The numerical results obtained using the new linking between branches coefficient definition, K, show a logarithmic relationship with mass flow rate ratio between branches, q , and the extrapolated Mach number in the common branch, M*3 , for all flow types studied in a 90 degree T-junction. Reliable and practical two parameters or global correlations, K=K(M*3,q), have been btained. These correlations can be easily implemented as boundary conditions into 1-D global simulation codes.

Ovaj magistarski rad bavi se simulacijom prikaza terena visokih rezolucija u stvarnom vremenu. Zbog velike količine podataka za obradu, ovo postavlja prevelike zahtjeve za današnja računala, te je potrebno načiniti algoritam koji će smanjiti količinu podataka bez narušavanja vizualnih karakteristika terena. U prvom dijelu opisane su neke od najznačajnijih metoda za simulaciju terena visokih rezolucija te njihova dobra svojstva i nedostaci. U drugom dijelu rada opisan je nov algoritam za simulaciju, koji je nastao djelomično kombinirajući tehnike iz prethodnih metoda, a djelomično upotrebljavajući svježe ideje. Implementacija algoritma je pokazala je da se može korisno upotrijebiti na osobnim računalima, uz glatku i vrlo podesivu animaciju. This thesis focuses on real-time simulation of large scale, detail rich terrains. Such terrains contain vast amounts of data that needs to be displayed, which presents a problem even for the fastest personal computers. Therefore, an algorithm is needed, which will be able to just a portion of available data at any given time, and still achieve nearly the same visual quality, without introducing any visible artefacts into the simulation. The thesis begins by describing and comparing several well established algorithms, which take different approaches to terrain visualization. Then, combining several techniques and features of these algorithms with some new ideas, a novel method for real-time large scale terrain simulation was created. Results of method implementation have shown that this method can indeed be used for simulations on personal computers of today, maintaining smooth and very adjustable animation at all times.

We propose a statistical criterion of digital curves regularity. It is not defined from an a priori model but a contrario to some statistics on random walks. This allows to automatically define detection thresholds in terms of a false detection rate. We apply this algorithm to the level lines of gray level images and experimentally check the statement of the Gestalt Theory following which regularity makes curve conspicuous without any contrast information, and that edges are really often good continuations. We also define good continuations breakings, which are good candidates for T-junctions, corners and Julesz's terminators. We also show that detection is not improved by shape scale space.

Es wird ein Berechnungsverfahren zur Bestimmung der Streuparameter der seitlichen Ankopplung eines Rechteckhohlleiters an einen Rundhohlleiter vorgestellt. Die Anordnung wird in einen Resonator- und drei Hohlleiterbereiche unterteilt. Mit der Methode nach Kühn [1] lassen sich geeignete Ansätze für die Vektorpotentiale finden. Aus den Randbedingungen für das elektromagnetische Feld ergibt sich mit Hilfe der Orthogonalreihenentwicklung ein unendliches System linearer Gleichungen für die Bestimmung der Streuparameter, das abgebrochen und mit numerischen Verfahren gelöst wird. An zwei Beispielen wird die Richtigkeit des Rechenverfahrens durch den Vergleich der berechneten mit gemessenen Streuparametern belegt. © 1994, Walter de Gruyter. Alle Rechte vorbehalten.

Road traffic injuries claim more than 1.2 million lives each year in the world and have a huge impact on health and development. It is commonly acknowledged that the human factor and the interaction between the human factor and the road environment are among the most common causes of road accidents. Intersections are among the most complex road environments: their geometric and traffic characteristics weigh the driver workload, affecting the driving behaviour and consequently the risk of accident. This study intends therefore to contribute for a better understanding of the relationship between different types of intersection and the human factor. The ultimate aim is to understand how at grade intersections affect the driving behaviour by comparing the drivers’ stress level for roundabouts and standard intersections. Electrodermal activity can provide a real-time assessment of the driver's stress level. Electrodermal activity was therefore collected continuously during a driving study which took place on a test environment based at Cranfield University and surrounding roads. Twenty participants were involved within the study. The analysis focused on four crossing manoeuvres on three at grade intersections (two T-junctions and a roundabout) situated on the study location. Results showed that the number of SCR peaks as well as the amplitude of the peaks are overall higher for the two manoeuvres on the roundabout. The stress level induced by each type of intersection was evaluated through an Electrodermal Impact Index which takes into account both the number and the amplitude of SCR peaks. Results suggested that the stress level induced by roundabouts is more than double that induced by standard intersections.

Analysis-suitable T-splines (ASTS) including both extraordinary points and T-junctions are used to solve Kirchhoff-Love shell problems. Extraordinary points are required to represent surfaces with arbitrary topological genus. T-junctions enable local refinement of regions where increased resolution is needed. The benefits of using ASTS to define shell geometries are at least two-fold: (1) The manual and time-consuming task of building a new mesh from scratch using the CAD geometry as an input is avoided and (2) C-1 or higher inter-element continuity enables the discretization of shell formulations in primal form defined by fourth-order partial differential equations. A complete and state-of-the-art description of the development of ASTS, including extraordinary points and T-junctions, is presented. In particular, we improve the construction of C-1-continuous non-negative spline basis functions near extraordinary points to obtain optimal convergence rates with respect to the square root of the number of degrees of freedom when solving linear elliptic problems. The applicability of the proposed technology to shell analysis is exemplified by performing geometrically nonlinear Kirchhoff-Love shell simulations of a pinched hemisphere, an oil sump of a car, a pipe junction, and a B-pillar of a car with 15 holes. Building ASTS for these examples involves using T-junctions and extraordinary points with valences 3, 5, and 6, which often suffice for the design of free-form surfaces. Our analysis results are compared with data from the literature using either a seven-parameter shell formulation or Kirchhoff-Love shells. We have also imported both finite element meshes and ASTS meshes into the commercial software LS-DYNA, used Reissner-Mindlin shells, and compared the result with our Kirchhoff-Love shell results. Excellent agreement is found in all cases. The complexity of the shell geometries considered in this paper shows that ASTS are applicable to real-world industrial problems. (C) 2019 Elsevier B.V. All rights reserved.

Comunicació presentada al congrés International Conference on Computer Vision Theory and Applications celebrat del 27 al 29 de febrer de 2016 a Roma, Itàlia. In this paper we propose a method to estimate a global depth order between the objects of a scene using information from a single image coming from an uncalibrated camera. The method we present stems from early vision cues such as occlusion and convexity and uses them to infer both a local and a global depth order. Monocular occlusion cues, namely, T-junctions and convexities, contain information suggesting a local depth order between neighbouring objects. A combination of these cues is more suitable, because, while information conveyed by T-junctions is perceptually stronger, they are not as prevalent as convexity cues in natural images. We propose a novel convexity detector that also establishes a local depth order. The partial order is extracted in T-junctions by using a curvature-based multi-scale feature. Finally, a global depth order, i.e., a full order of all shapes that is as consistent as possible with the computed partial orders that can tolerate conflicting partial or ders is computed. An integration scheme based on a Markov chain approximation of the rank aggregation problem is used for this purpose. The experiments conducted show that the proposed method compares favorably with the state of the art. The authors acknowledge partial support by MICINN project, reference MTM2012-30772, and by GRC reference 2014 SGR 1301, Generalitat de Catalunya.