Stereo-Based Head Pose Tracking Using Iterative Closest Point and Normal Flow Constraint

In this text, we present two stereo-based head tracking techniques along with a fast 3D model acquisition system. The first tracking technique is a robust implementation of stereo-based head tracking designed for interactive environments with uncontrolled lighting. We integrate fast face detection and drift reduction algorithms with a gradient-based stereo rigid motion tracking technique. Our system can automatically segment and track a user's head under large rotation and illumination variations. Precision and usability of this approach are compared with previous tracking methods for cursor control and target selection in both desktop and interactive room environments. The second tracking technique is designed to improve the robustness of head pose tracking for fast movements. Our iterative hybrid tracker combines constraints from the ICP (Iterative Closest Point) algorithm and normal flow constraint. This new technique is more precise for small movements and noisy depth than ICP alone, and more robust for large movements than the normal flow constraint alone. We present experiments which test the accuracy of our approach on sequences of real and synthetic stereo images. The 3D model acquisition system we present quickly aligns intensity and depth images, and reconstructs a textured 3D mesh. 3D views are registered with shape alignment based on our iterative hybrid tracker. We reconstruct the 3D model using a new Cubic Ray Projection merging algorithm which takes advantage of a novel data structure: the linked voxel space. We present experiments to test the accuracy of our approach on 3D face modelling using real-time stereo images.

Output from the 1998 Product Development Value Stream Workshop: A Framework for Understanding Information Flow in the Product Development Process

The descriptions below and the attached diagrams are outputs of the 1998 LAI Product Development Focus Team workshop on the Value Chain in Product Development. A working group at that workshop was asked to model the product development process: in terms of the phases of product development and their interfaces, boundaries and outputs. Their work has proven to be generally useful to LAI researchers and industry members, and so is formalized here.

Scaling algorithms for distributed max flow

Bibliography: p. 22-24.

FastAero – A Precorrected FFT – Fast Multipole Tree Steady and Unsteady Potential Flow Solver

In this paper a precorrected FFT-Fast Multipole Tree (pFFT-FMT) method for solving the potential flow around arbitrary three dimensional bodies is presented. The method takes advantage of the efficiency of the pFFT and FMT algorithms to facilitate more demanding computations such as automatic wake generation and hands-off steady and unsteady aerodynamic simulations. The velocity potential on the body surfaces and in the domain is determined using a pFFT Boundary Element Method (BEM) approach based on the Green’s Theorem Boundary Integral Equation. The vorticity trailing all lifting surfaces in the domain is represented using a Fast Multipole Tree, time advected, vortex participle method. Some simple steady state flow solutions are performed to demonstrate the basic capabilities of the solver. Although this paper focuses primarily on steady state solutions, it should be noted that this approach is designed to be a robust and efficient unsteady potential flow simulation tool, useful for rapid computational prototyping.

Numerical Simulation of Electroosmotic Flow with Step Change in Zeta Potential

Electroosmotic flow is a convenient mechanism for transporting polar fluid in a microfluidic device. The flow is generated through the application of an external electric field that acts on the free charges that exists in a thin Debye layer at the channel walls. The charge on the wall is due to the chemistry of the solid-fluid interface, and it can vary along the channel, e.g. due to modification of the wall. This investigation focuses on the simulation of the electroosmotic flow (EOF) profile in a cylindrical microchannel with step change in zeta potential. The modified Navier-Stoke equation governing the velocity field and a non-linear two-dimensional Poisson-Boltzmann equation governing the electrical double-layer (EDL) field distribution are solved numerically using finite control-volume method. Continuities of flow rate and electric current are enforced resulting in a non-uniform electrical field and pressure gradient distribution along the channel. The resulting parabolic velocity distribution at the junction of the step change in zeta potential, which is more typical of a pressure-driven velocity flow profile, is obtained.

The Inertio-Elastic Planar Entry Flow of Low-Viscosity Elastic Fluids in Micro-fabricated Geometries

The non-Newtonian flow of dilute aqueous polyethylene oxide (PEO) solutions through microfabricated planar abrupt contraction-expansions is investigated. The contraction geometries are fabricated from a high-resolution chrome mask and cross-linked PDMS gels using the tools of soft-lithography. The small length scales and high deformation rates in the contraction throat lead to significant extensional flow effects even with dilute polymer solutions having time constants on the order of milliseconds. The dimensionless extra pressure drop across the contraction increases by more than 200% and is accompanied by significant upstream vortex growth. Streak photography and videomicroscopy using epifluorescent particles shows that the flow ultimately becomes unstable and three-dimensional. The moderate Reynolds numbers (0.03 ≤ Re ≤ 44) associated with these high Deborah number (0 ≤ De ≤ 600) microfluidic flows results in the exploration of new regions of the Re-De parameter space in which the effects of both elasticity and inertia can be observed. Understanding such interactions will be increasingly important in microfluidic applications involving complex fluids and can best be interpreted in terms of the elasticity number, El = De/Re, which is independent of the flow kinematics and depends only on the fluid rheology and the characteristic size of the device.

Viscous Flow and Fluid Dynamics

Exam questions and solutions for a third year maths course. Diagrams for the questions are all together in the support.zip file, as .eps files

On the Foundations of Quantitative Information Flow

The paper introduces vulnerability and quantitative privacy. Optional reading

Open Equipment data flow

Short set of slides explaining the workflow from a university website to equipment.data.ac.uk

Genome-wide evidence for speciation with gene flow in Heliconius butterflies

Most speciation events probably occur gradually, without complete and immediate reproductive isolation, but the full extent of gene flow between diverging species has rarely been characterized on a genome-wide scale. Documenting the extent and timing of admixture between diverging species can clarify the role of geographic isolation in speciation. Here we use new methodology to quantify admixture at different stages of divergence in Heliconius butterflies, based on whole-genome sequences of 31 individuals. Comparisons between sympatric and allopatric populations of H. melpomene, H. cydno, and H. timareta revealed a genome-wide trend of increased shared variation in sympatry, indicative of pervasive interspecific gene flow. Up to 40% of 100-kb genomic windows clustered by geography rather than by species, demonstrating that a very substantial fraction of the genome has been shared between sympatric species. Analyses of genetic variation shared over different time intervals suggested that admixture between these species has continued since early in speciation. Alleles shared between species during recent time intervals displayed higher levels of linkage disequilibrium than those shared over longer time intervals, suggesting that this admixture took place at multiple points during divergence and is probably ongoing. The signal of admixture was significantly reduced around loci controlling divergent wing patterns, as well as throughout the Z chromosome, consistent with strong selection for Müllerian mimicry and with known Z-linked hybrid incompatibility. Overall these results show that species divergence can occur in the face of persistent and genome-wide admixture over long periods of time.

Predicción del flow disposicional según clima motivacional y el trato generado por el profesor en clase de Educación Física.

Resumen tomado de la publicación

La educación de los sordomudos y ciegos en el BILE.

Se analizan las referencias que aparecen en el BILE (Boletín de la Institución Libre de Enseñanza) sobre la educación de los deficientes auditivos y oculares. Se puede afirmar la preocupación de los institucionistas por dar a conocer la situación real de los afectados por este tipo de deficiencias físicas, así como dar a conocer las tendencias pedagógicas y médicas que se estaban poniendo en práctica en otros lugares del mundo. El BILE encarnó el espíritu reformador e innovador de la enseñanza en nuestro país, el esfuerzo para que España avanzará en la formación de sus jóvenes, el de crear centros vanguardistas en la concepción de pedagogía en todos sus ámbitos, así como en la aplicación de las nuevas corrientes pedagógicas en su organización.

El boletín de la institución libre de enseñanza BILE.

En este artículo presento un análisis descriptivo del Boletín de la Institución Libre de Enseñanza en sus dos épocas de existencia. Periodos delimitados por los acontecimientos de nuestra guerra civil. La PRIMERA es la más importante por su duración, abarca sesenta años de publicación ininterrumpida, desde el año 1877 hasta la mitad de 1936. La SEGUNDA época del B.I.L.E, es relativamente reciente, reaparece en 1987 y lo edita la Fundación Francisco Giner de los Ríos. El revisar que misión se propuso esta revista, sus comienzos, evolución y estructuras contribuirá al convencimiento de que el Boletín constituye una fuente documental valiosísima e imprescindible para el estudioso de la Institución Libre de Enseñanza y también para quien quiera profundizar en la evolución de la Historia de la Educación Española de finales del siglo XIX y comienzos del XX. Especialmente es fuente necesaria para conocer nuestra incorporación al Movimiento Pedagógico de la Escuela Nueva, directrices educativas que fueron seguidas por la I.L.E y de cuyos principios y realizaciones ha quedado constancia en las páginas de su Boletín.

Análisis de las relaciones entre orientaciones de meta, clima motivacional, valoración de la Educación Física y flow disposicional en estudiantes de Educación Física en secundaria.

Resumen tomado de la publicación

Motivación, comportamientos de disciplina, trato de igualdad y flow disposicional en estudiantes de educación física.

Analizar las relaciones existentes dentro del entorno marcado por la educación física entre cuatro factores claramente diferenciados: la motivación del alumno hacia las clases, la que genera el profesor, los comportamientos disciplinados e indisciplinados, la percepción de la igualdad en el trato entre chicos y chicas y el flow disposicional mostrado en la mejor experiencia sentida por el alumno en sus clases. . Población de estudiantes de primer ciclo de ESO de la Comunidad Valenciana. Muestra compuesta por un total de 1103 alumnos pertenecientes al segundo curso de ESO de centros públicos y privados de la provincia de Alicante. Los instrumentos empleados para recoger la información son: Cuestionario de Percepción del Éxito (Cervelló, Escartí y Balagué, 1999); Instrumento de Medición del Clima Motivacional en las Clases de Educación Física (Cervelló, Moreno, Del Villar y Reina, 2006); Cuestionario de Conductas de Disciplina-Indisciplina en Educación Física (Cervelló, Jiménez, Nerea, Ramos, Del Villar y Santos-Rosa, 2002); Cuestionario de Percepción de Igualdad-Discriminación en Educación Física (Cervelló, Jiménez, Del Villar, Ramos y Santos-Rosa, 2004); Escala de Flow Dispocicional (Jackson, 2000. Traducida por Cervelló, Nerea, Jiménez, García-Calvo y santos-Rosa, 2001). Se utilizó el análisis factorial de componentes principales con rotación varimax para todos los cuestionarios con el fin de determinar su estructura. Se aplica el análisis de correlación para descubrir las relaciones entre variables del estudio. El análisis jerárquico de cluster para identificar los perfiles motivacionales de los alumnos que componen la muestra de estudio atendiendo a las variables de orientación disposicional, clima motivacional percibido, disciplina, coeducación y flow disposicional y el análisis de ecuaciones estructurales para testar los modelos teóricos de la investigación.. Es de vital importancia que el profesor de educación física cree un adecuado clima motivacional implicante en la tarea porque será así facilitador de un trato justo y ecuánime hacia todos sus alumnos, generador de un buen ambiente de clase debido al buen comportamiento de sus discentes ocasionado por la preocupación de éstos hacia el aprendizaje de la materia impartida y fomentador de un estado psicológico óptimo que le ayude a concentrar su atención sobre la actividad a realizar obteniendo como resultado una experiencia enriquecedora y satisfactoria..