Exploring Material Representations for Sparse Voxel DAGs

Ray tracing is a popular technique used in movies and video games to create compelling visuals. Ray traced computer images are increasingly becoming more realistic and almost indistinguishable from real-word images. Due to the complexity of scenes and the desire for high resolution images, ray tracing can become very expensive in terms of computation and memory. To address these concerns, researchers have examined data structures to efficiently store geometric and material information. Sparse voxel octrees (SVOs) and directed acyclic graphs (DAGs) have proven to be successful geometric data structures for reducing memory requirements. Moxel DAGs connect material properties to these geometric data structures, but experience limitations related to memory, build times, and render times. This thesis examines the efficacy of connecting an alternative material data structure to existing geometric representations. The contributions of this thesis include the creation of a new material representation using hashing to accompany DAGs, a method to calculate surface normals using neighboring voxel data, and a demonstration and validation that DAGs can be used to super sample based on proximity. This thesis also validates the visual acuity from these methods via a user survey comparing different output images. In comparison to the Moxel DAG implementation, this work increases render time, but reduces build times and memory, and improves the visual quality of output images

Hierarchical Coupling of Molecular Dynamics and Micromechanics to Predict the Elastic Properties of Three-Phase and Four-Phase Silicon Carbide Composites

The results obtained from previously conducted molecular dynamics analysis of silicon carbide (-SiC (6H, 4H, & 2H-SiC), -SiC (3C SiC)), silicon and boron nitride, were utilized as inputs in the MAC/GMC micromechanics software to model and evaluate the elastic properties of three-phase SiC/BN/SiC and four-phase SiC/BN/Si/SiC composites. This method of analysis eliminates the need for back-calculation of the apparent properties of the base constituents from the measured ceramic matrix composites properties. The multiscale models are validated against the available data in literature

Optimización en la distribución de rutas de colegios privados en Pereira con ayuda de algoritmos de inteligencia artificial

En este proyecto se realizó o una investigación de los distintos algoritmos utilizados para resolver el problema de enrutamiento de vehículos, VRP, con el fi n de facilitar esta tarea a los encargados de rutas en los colegios privados de la ciudad de Pereira. de acuerdo a los resultados encontrados y al conocimiento en algoritmos se eligieron dos para llevarlos a una aplicación con la que se puede optimizar la distribución de rutas para un mapa, un conjunto de estudiantes y unas rutas dadas, minimizando los recorridos basados en la distancia geográficamentre los estudiantes. Los algoritmos de inteligencia artificial usados fueron el Gen ético y el Recocido Simulado (Simulated Annealing). Se realizaron pruebas con dos colegios privados, el Liceo Taller San Miguel y el Saint Andrews, ubicados en la v ía a Armenia y en la vía a Cerritos respectivamente, las dos zonas con mayor concentración de colegios privados de la ciudad. Se identificaron las mejores configuraciones y combinación de los algoritmos dados y se pudieron observar resultados satisfactorios en la medida en que no se logran identificar mejoras

Sistema automático de recomendación de outfits utilizando visión por computador y técnicas de aprendizaje de maquinas con un guardarropas personalizado

Decidir cómo combinar la ropa es un problema que afrontamos día a día, pocos tenemos la habilidad de saber qué va bien con qué pero a todos nos interesa vernos bien. La dificultad de abordar este problema es alta ya que para entrenar un modelo que pueda tomar decisiones de coordinación correctas es necesario previamente segmentar cada imagen, extraer características de esta y ensamblarlas. De acuerdo a esto se construye una base de datos con ayuda de una diseñadora de modas, en la cual se tiene el rating para miles de combinaciones de prendas..

Comparison of gold extraction yields by cyanide treatment vs. bioleaching procedure

Samples from the tailings of the Picacho mine in California were leached using NaCN and native bacteria, Alcaligenes faecalis, in column experiments to compare the gold recovery yields in the effluents. Four columns were treated with a different liquid: water, bacteria, NaCN and a mixture of cyanide and bacteria. After they were leached the effluents were analyzed to determine gold yields. During experiment I the total Au recovered in the effluent in the column treated with bacteria was only 10.09% less than those treated with cyanide (C2) and 81.7% more than the control. In experiment II, Au values measured were below detection limits. In experiment III Au recovered in the effluents for the Bacteria Column was 18.51% less than the Cyanide (C2) column and 34.27% more than the control.. Mass balance calculations for experiment I show that the column treated with bacteria has a higher percentage recovery yield of the Au recovered in both the effluent (18%) and in the two columns treated with cyanide (13% and 15%, respectively). In experiment III, mass balance calculations show that the percentage of Au recovered in the effluents of the columns treated with the bacteria was 15% and the other two columns trreated with cyanide had 25% of Au from the effluents. These findings indicates that the use of A.faecalis as an encouraging option for Au leaching of mine tailings which requires little supervision that translates in lower costs. The leaching treatment with bacteria produced favorable results that challenge cyanidation

Achieving ICME with Multiscale Modeling: The Effects of Constituent Properties and Processing on the Performance of Laminated Polymer Matrix Composite Structures

Integrated computational materials engineering (ICME) is a useful approach for tailoring the performance of a material. For fiber-reinforced composites, not only do the properties of the constituents of the composite affect the performance, but so does the architecture (or microstructure) of the constituents. The generalized method of cells is demonstrated to be a viable micromechanics tool for determining the effects of the microstructure on the performance of laminates. The micromechanics is used to predict the inputs for a macroscale model for a variety of different fiber volume fractions, and fiber architectures. Using this technique, the material performance can be tailored for specific applications by judicious selection of constituents, volume fraction, and architectural arrangement given a particular manufacturing scenari

Effects of Subscale Size and Shape on Global Energy Dissipation in a Multiscale Model of a Fiber-Reinforced Composite Exhibiting Post-Peak Strain Softening Using Abaqus and FEAMAC

A mesh objective crack band model is implemented in the generalized method of cells (GMC) micromechanics model to predict failure of a composite repeating unit cell (RUC). The micromechanics calculations are achieved using the MAC/GMC core engine within the ImMAC suite of micromechanics codes, developed at the NASA Glenn Research Center. The microscale RUC is linked to a macroscale Abaqus/Standard finite element model using the FEAMAC multiscale framework (included in the ImMAC suite). The effects of the relationship between the characteristic length of the finite element and the size of the microscale RUC on the total energy dissipation of the multiscale model are investigated. A simple 2-D composite square subjected to uniaxial tension is used to demonstrate the effects of scaling the dimensions of the RUC such that the length of the sides of the RUC are equal to the characteristic length of the finite element. These results are compared to simulations where the size of the RUC is fixed, independent of the element size. Simulations are carried out for a variety of mesh densities and element shapes, including square and triangular. Results indicate that a consistent size and shape must be used to yield preserve energy dissipation across the scales

Progressive Failure of a Unidirectional Fiber-Reinforced Composite Using the Method of Cells: Discretization Objective Computational Results

The smeared crack band theory is implemented within the generalized method of cells and high-fidelity generalized method of cells micromechanics models to capture progressive failure within the constituents of a composite material while retaining objectivity with respect to the size of the discretization elements used in the model. An repeating unit cell containing 13 randomly arranged fibers is modeled and subjected to a combination of transverse tension/compression and transverse shear loading. The implementation is verified against experimental data (where available), and an equivalent finite element model utilizing the same implementation of the crack band theory. To evaluate the performance of the crack band theory within a repeating unit cell that is more amenable to a multiscale implementation, a single fiber is modeled with generalized method of cells and high-fidelity generalized method of cells using a relatively coarse subcell mesh which is subjected to the same loading scenarios as the multiple fiber repeating unit cell. The generalized method of cells and high-fidelity generalized method of cells models are validated against a very refined finite element model

Modelling of Fiber/Matrix Debonding of Composites Under Cyclic Loading

The micromechanics theory, generalized method of cells (GMC), was employed to simulate the debonding of fiber/matrix interfaces, within a repeating unit cell subjected to global, cyclic loading, utilizing a cyclic crack growth law. Cycle dependent, interfacial debonding was implemented as a new module to the available GMC formulation. The degradation of interfacial stresses, with applied load cycles, was achieved via progressive evolution of the interfacial compliance. A periodic repeating unit cell, representing the fiber/matrix architecture of a composite, was subjected to combined normal and shear loadings, and degradation of the global transverse stress in successive cycles was monitored. The obtained results were compared to values from a corresponding finite element model. Reasonable agreement was achieved for combined normal and shear loading conditions, with minimal variation for pure loading cases. The local effects of interfacial debonding, and fatigue damage will later be combined as sub-models to predict the experimentally obtained fatigue life of Ti-15-3/Sic composites at the laminate level