Monte Carlo simulation of interface alloying

An Ising-like model, with interactions ranging up to next-nearest-neighbor pairs, is used to simulate the process of interface alloying. Interactions are chosen to stabilize an intermediate "antiferromagnetic" ordered structure. The dynamics proceeds exclusively by atom-vacancy exchanges. In order to characterize the process, the time evolution of the width of the intermediate ordered region and the diffusion length is studied. Both lengths are found to follow a power-law evolution with exponents depending on the characteristic features of the model.

Freezing of 4He and its liquid-solid interface from density functional theory

We show that, at high densities, fully variational solutions of solidlike types can be obtained from a density functional formalism originally designed for liquid 4He . Motivated by this finding, we propose an extension of the method that accurately describes the solid phase and the freezing transition of liquid 4He at zero temperature. The density profile of the interface between liquid and the (0001) surface of the 4He crystal is also investigated, and its surface energy evaluated. The interfacial tension is found to be in semiquantitative agreement with experiments and with other microscopic calculations. This opens the possibility to use unbiased density functional (DF) methods to study highly nonhomogeneous systems, like 4He interacting with strongly attractive impurities and/or substrates, or the nucleation of the solid phase in the metastable liquid.

MgO/Ag(001) interface structure and STM images from first principles

The interface of MgO/Ag(001) has been studied with density functional theory applied to slabs. We have found that regular MgO films show a small adhesion to the silver substrate, the binding can be increased in off-stoichiometric regimes, either by the presence of O vacancies at the oxide film or by a small excess of O atoms at the interface between the ceramic to the metal. By means of theoretical methods, the scanning tunneling microscopy signatures of these films is also analyzed in some detail. For defect free deposits containing 1 or 2 ML and at low voltages, tunnelling takes place from the surface Ag substrate, and at large positive voltages Mg atoms are imaged. If defects, oxygen vacancies, are present on the surface of the oxide they introduce much easier channels for tunnelling resulting in big protrusions and controlling the shape of the image, the extra O stored at the interface can also be detected for very thin films.

Influence of Interface Surface Geometries In The Tensile Characteristics Of Friction Welded Joints From Aluminium Alloys

Friction welding is a solid state joining process that produces coalescence in materials, using the heat developed between surfaces through a combination of mechanical induced rubbing motion and applied load. In rotary friction welding technique heat is generated by the conversion of mechanical energy into thermal energy at the interface of the work pieces during rotation under pressure. Traditionally friction welding is carried out on a dedicated machine because of its adaptability to mass production. In the present work, steps were made to modify a conventional lathe to rotary friction welding set up to obtain friction welding with different interface surface geometries at two different speeds and to carry out tensile characteristic studies. The surface geometries welded include flat-flat, flat-tapered, tapered-tapered, concave-convex and convex-convex. A comparison of maximum load, breaking load and percentage elongation of different welded geometries has been realized through this project. The maximum load and breaking load were found to be highest for weld formed between rotating flat and stationary tapered at 500RPM and the values were 19.219kN and 14.28 kN respectively. The percentage elongation was found to be highest for weld formed between rotating flat and stationary flat at 500RPM and the value was 21.4%. Hence from the studies it is cleared that process parameter like “interfacing surface geometries” of weld specimens have strong influence on tensile characteristics of friction welded joints

A crack on the interface of piezo-electric bodies

Singularities of elastic and electric fields are investigated at the tip of a crack on the interface of two anisotropic piezo-electric media under various boundary conditions on the crack surfaces. The Griffith formulae are obtained for increments of energy functionals due to growth of the crack and the notion of the energy release matrix is introduced. Normalization conditions for bases of singular solution are proposed to adapt them to the energy, stress, and deformation fracture criteria. Connections between these bases are determined and additional properties of the deformation basis related to the notion of electric surface enthalpy are established.

Interface issues in the ESCHER visual database editor

Presentation at the 1997 Dagstuhl Seminar "Evaluation of Multimedia Information Retrieval", Norbert Fuhr, Keith van Rijsbergen, Alan F. Smeaton (eds.), Dagstuhl Seminar Report 175, 14.04. - 18.04.97 (9716). - Abstract: This presentation will introduce ESCHER, a database editor which supports visualization in non-standard applications in engineering, science, tourism and the entertainment industry. It was originally based on the extended nested relational data model and is currently extended to include object-relational properties like inheritance, object types, integrity constraints and methods. It serves as a research platform into areas such as multimedia and visual information systems, QBE-like queries, computer-supported concurrent work (CSCW) and novel storage techniques. In its role as a Visual Information System, a database editor must support browsing and navigation. ESCHER provides this access to data by means of so called fingers. They generalize the cursor paradigm in graphical and text editors. On the graphical display, a finger is reflected by a colored area which corresponds to the object a finger is currently pointing at. In a table more than one finger may point to objects, one of which is the active finger and is used for navigating through the table. The talk will mostly concentrate on giving examples for this type of navigation and will discuss some of the architectural needs for fast object traversal and display. ESCHER is available as public domain software from our ftp site in Kassel. The portable C source can be easily compiled for any machine running UNIX and OSF/Motif, in particular our working environments IBM RS/6000 and Intel-based LINUX systems. A porting to Tcl/Tk is under way.

Pi: A Parallel Architecture Interface for Multi-Model Execution

This thesis defines Pi, a parallel architecture interface that separates model and machine issues, allowing them to be addressed independently. This provides greater flexibility for both the model and machine builder. Pi addresses a set of common parallel model requirements including low latency communication, fast task switching, low cost synchronization, efficient storage management, the ability to exploit locality, and efficient support for sequential code. Since Pi provides generic parallel operations, it can efficiently support many parallel programming models including hybrids of existing models. Pi also forms a basis of comparison for architectural components.

An Immersed Interface Method for the Incompressible Navier-Stokes Equations in Irregular Domains

We present an immersed interface method for the incompressible Navier Stokes equations capable of handling rigid immersed boundaries. The immersed boundary is represented by a set of Lagrangian control points. In order to guarantee that the no-slip condition on the boundary is satisfied, singular forces are applied on the fluid at the immersed boundary. The forces are related to the jumps in pressure and the jumps in the derivatives of both pressure and velocity, and are interpolated using cubic splines. The strength of singular forces is determined by solving a small system of equations at each time step. The Navier-Stokes equations are discretized on a staggered Cartesian grid by a second order accurate projection method for pressure and velocity.

Millora d’un prototipus de control de qualitat de producció de paper pintat basat en visió per computador

L’objectiu d’aquest projecte és realitzar l’anàlisi, disseny i implementació d’una nova eina per analitzar les diferencies entre el paper que s’està produint i les mostres de referència, que millori els resultats obtinguts pel prototipus anterior i faciliti la interpretació dels resultats obtinguts, per part dels operaris de l’empresa. Partint de dos imatges escannejades que anomenem patró i mostra, que corresponen respectivament a les imatges de referència i de la mostra de producció

Integració d’un sistema de visió per computador a una cèl·lula flexible de transport

L’objectiu d’aquest projecte final de carrera és millorar les prestacions de la cel·la de fabricació actual duent a terme les següents fites: integració d’un sistema de visió artificial a la plataforma. Aquest sistema ha de permetre la detecció i anàlisi dels objectes transportats, augmentant les seves possibilitats de manipulació i classificació. Es pretén eliminar la restricció actual que obliga a col•locar les peces en una posició fixa de la safata de transport; control centralitzat del procés a través d’un ordinador. El procés serà operat a través d’un computador industrial, el qual controlarà els diferents sistemes que componen la cel·la per tal que duguin a terme les seves funcions de forma coordinada; disseny i implementació d’una API del sistema. Es desenvoluparà la llibreria de control del sistema per tal de facilitar la programació del procés

Reconeixement de cd-roms musicals mitjançant visió per computador

Dissenyar, implementar i testejar un sistema per classificar imatges: disseny d’un sistema que primer aprèn com són les imatges d’una classe a partir d’un conjunt d’imatges d’entrenament i després és capaç de classificar noves imatges assignant-les-hi l’ etiqueta corresponent a una de les classes “apreses”. Concretament s’analitzen caràtules de cd-roms, les quals s’han de reconèixer per després reproduir automàticament la música del seu àlbum associat

Desarrollo de una aplicación de computador para analizar parámetros estadísticos genético-poblacionales de microsatélites en poblaciones humanas

La información y los datos genéticos que emanan hoy de las investigaciones del genoma humano demandan el desarrollo de herramientas informáticas capaces de procesar la gran cantidad de información disponible. La mayor cantidad de datos genéticos es el resultado de equipos que realizan el análisis simultáneo de cientos o miles de polimorfismos o variaciones genéticas, de nuevas técnicas de laboratorio de mayor rendimiento que, en conjunto, ofrecen una mayor disponibilidad de información en un corto espacio de tiempo. Esta problemática conduce a la necesidad de desarrollar nuevas herramientas informáticas capaces de lidiar con este mayor volumen de datos genéticos. En el caso de la genética de poblaciones, a pesar de que existen herramientas informáticas que permiten procesar y facilitar el análisis de los datos, estas tienen limitaciones como la falta de conocimiento de los usuarios de algunos lenguajes de programación para alimentar la información y otras herramientas informáticas no realizan todas las estimaciones que se requieren y otros presentan limitaciones en cuanto al número de datos que pueden incorporar o manejar. En algunos casos hay redundancia al tener que usarse dos o más herramientas para poder procesar un conjunto de datos de información genética. El presente trabajo tiene por objetivo el desarrollo de una herramienta informática basada en aplicaciones de computador comunes, en este caso Microsoft Excel® y que resuelva todos los problemas y las limitaciones descritas antes. El desarrollo del conjunto de subprogramas que constituyen a Lustro; permiten superar lo anterior, presentar los resultados en un ambiente sencillo, conocido y fácil de operar, simplificando de esta forma el proceso de adaptación del usuario del programa, sin entrenamiento previo, obteniéndose en corto tiempo el procesamiento de la información genética de interés.

Lecture 15 - Interface this

A quick word about abstract How a class interfaces Making Pets The Deadly Diamond of Death Interfaces (not interfaces)

Orientación de la copa acetabular en cirugía asistida por computador versus técnica convencional en artroplastia de cadera

Introducción: El éxito de la artroplastia total de cadera depende de la orientación del componente acetabular; como alternativa para su corrección se han generado diferentes herramientas quirúrgicas, una de ella se asienta en los sistemas de cirugía asistidos por computador, el cual corrige y perfecciona la orientación de la copa acetabular. Objetivo: Comparar la inclinación y la anteversión de la copa acetabular implantadas por técnica convencional versus la realizada por cirugía asistida por computador Materiales y Métodos: Estudio descriptivo de comparación de dos cohortes de pacientes. Se evaluaron pacientes sometidos a reemplazo total de cadera en hospital Santa Clara desde Enero del 2009 a Diciembre del 2009 determinando el ángulo de inclinación acetabular y la anteversión acetabular, según las medidas establecidas en radiografía convencional postoperatoria. Resultados: No se encontraron diferencias estadísticamente significativas en la comparación de las puntuaciones promedio en anteversión e inclinación acetabular cuando se realiza cirugía tradicional o con la tecnología de navegación por computador. Conclusiones: El uso de navegadores por computador en la cirugía de reemplazo de cadera es especialmente útil para ortopedistas en entrenamiento y para aquellas situaciones donde la posición de los componentes acetabulares pueda garantizar buen resultado a largo plazo