Quadrature for second-order triangles in the Boundary Element Method

A quadrature method for second-order, curved triangular elements in the Boundary Element Method (BEM) is presented, based on a polar coordinate transformation, combined with elementary geometric operations. The numerical performance of the method is presented using results from solution of the Laplace equation on a cat's eye geometry which show an error of order $P^{-1.6}$, where $P$ is the number of elements.Comment: 14 pages; 6 figures; submitted to International Journal for Numerical Methods in Engineerin

Intersection of a line and a convex hull of points cloud

An algorithm for intersection a line and a convex hull of points cloud is presented. The algorithm doesn't require the convex hull construction. The points cloud can be arbitrary and not sorted, no topology, face list or edge list is known. The algorithm uses only vertices coordinates. Standard transformation of coordinates is performed and the points cloud is bisected by two perpendicular planes. Yielded 1D points set lies at the line. Bounds of the set are intersection points of the points cloud and the line. The algorithm was compared against the obvious algorithm which uses intersection of the line and all possible faces (sets of three points). Presented algorithm is much faster than the obvious one. © 2013 R. P. Koptelov and A. M. Konashkova

GPU ray tracing with CUDA

Ray Tracing is a rendering method that generates high quality images by simulating how light rays interact with objects in a virtual scene. The ray tracing technique can accurately portray advanced optical effects, such as reflections, refractions, and shadows, but at a greater computational cost and rendering time than other rendering methods. Fortunately, technological advances in GPU computing have provided the means to accelerate the ray tracing process to produce images in a significantly shorter time. This paper attempts to clearly illustrate the difference in rendering speed and design by developing and comparing a sequential CPU and parallel GPU implementation of a ray tracer, written in C++ and CUDA respectively. A performance analysis reveals that the optimized GPU ray tracer is capable of producing images with speedup gains up to 1852X when compared to the former CPU implementation --Document

A fast reconstruction algorithm for time-resolved X-ray tomography in bubbling fluidized beds

A new tomographic reconstruction algorithm is proposed for fast image reconstruction. The results are based on a high speed X-ray tomography system, consisting of 3 X-ray sources and 32 detectors for each source. The proposed algorithm combines void measurements of each X-ray beam into a triangular mesh, which is formed by the intersection points of all the beams. Simulations and real fluidized bed data are utilized to assess the quality of the proposed algorithm compared to the Simultaneous Algebraic Reconstruction Technique (SART). The influence of the number, position and diameter of the phantoms on the proposed reconstruction method is studied. The new method provides images with similar quality to SART reconstructions, although obtaining smaller bubble sizes. The low computing time needed to reconstruct each image with the new method, which is more than 5000 times faster than SART for a 40 × 40 mesh, encourages the use of the new method for the online image reconstruction of X-ray measurements

The Iray Light Transport Simulation and Rendering System

While ray tracing has become increasingly common and path tracing is well understood by now, a major challenge lies in crafting an easy-to-use and efficient system implementing these technologies. Following a purely physically-based paradigm while still allowing for artistic workflows, the Iray light transport simulation and rendering system allows for rendering complex scenes by the push of a button and thus makes accurate light transport simulation widely available. In this document we discuss the challenges and implementation choices that follow from our primary design decisions, demonstrating that such a rendering system can be made a practical, scalable, and efficient real-world application that has been adopted by various companies across many fields and is in use by many industry professionals today

The use of primitives in the calculation of radiative view factors

Compilations of radiative view factors (often in closed analytical form) are readily available in the open literature for commonly encountered geometries. For more complex three-dimensional (3D) scenarios, however, the effort required to solve the requisite multi-dimensional integrations needed to estimate a required view factor can be daunting to say the least. In such cases, a combination of finite element methods (where the geometry in question is sub-divided into a large number of uniform, often triangular, elements) and Monte Carlo Ray Tracing (MC-RT) has been developed, although frequently the software implementation is suitable only for a limited set of geometrical scenarios. Driven initially by a need to calculate the radiative heat transfer occurring within an operational fibre-drawing furnace, this research set out to examine options whereby MC-RT could be used to cost-effectively calculate any generic 3D radiative view factor using current vectorisation technologies

Intelligent Computational Transportation

Transportation is commonplace around our world. Numerous researchers dedicate great efforts to vast transportation research topics. The purpose of this dissertation is to investigate and address a couple of transportation problems with respect to geographic discretization, pavement surface automatic examination, and traffic ow simulation, using advanced computational technologies. Many applications require a discretized 2D geographic map such that local information can be accessed efficiently. For example, map matching, which aligns a sequence of observed positions to a real-world road network, needs to find all the nearby road segments to the individual positions. To this end, the map is discretized by cells and each cell retains a list of road segments coincident with this cell. An efficient method is proposed to form such lists for the cells without costly overlapping tests. Furthermore, the method can be easily extended to 3D scenarios for fast triangle mesh voxelization. Pavement surface distress conditions are critical inputs for quantifying roadway infrastructure serviceability. Existing computer-aided automatic examination techniques are mainly based on 2D image analysis or 3D georeferenced data set. The disadvantage of information losses or extremely high costs impedes their effectiveness iv and applicability. In this study, a cost-effective Kinect-based approach is proposed for 3D pavement surface reconstruction and cracking recognition. Various cracking measurements such as alligator cracking, traverse cracking, longitudinal cracking, etc., are identified and recognized for their severity examinations based on associated geometrical features. Smart transportation is one of the core components in modern urbanization processes. Under this context, the Connected Autonomous Vehicle (CAV) system presents a promising solution towards the enhanced traffic safety and mobility through state-of-the-art wireless communications and autonomous driving techniques. Due to the different nature between the CAVs and the conventional Human- Driven-Vehicles (HDVs), it is believed that CAV-enabled transportation systems will revolutionize the existing understanding of network-wide traffic operations and re-establish traffic ow theory. This study presents a new continuum dynamics model for the future CAV-enabled traffic system, realized by encapsulating mutually-coupled vehicle interactions using virtual internal and external forces. A Smoothed Particle Hydrodynamics (SPH)-based numerical simulation and an interactive traffic visualization framework are also developed

Developing an efficient algorithm for computing Solar Radiation Pressure

The main goal for this master's degree final thesis is to propose an alternative way of computing solar radiation pressure. Solar radiation pressure is the impact of the photons emitted by the Sun onto a satellite. This impact generates acceleration that is important to model satellite's motion