Search results for "Virtual"
showing 10 items of 1485 documents
Loss of coherence and dressing in QED
2006
The dynamics of a free charged particle, initially described by a coherent wave packet, interacting with an environment, i.e. the electromagnetic field characterized by a temperature $T$, is studied. Using the dipole approximation the exact expressions for the evolution of the reduced density matrix both in momentum and configuration space and the vacuum and the thermal contribution to decoherence, are obtained. The time behaviour of the coherence lengths in the two representations are given. Through the analysis of the dynamic of the field structure associated to the particle the vacuum contribution is shown to be linked to the birth of correlations between the single momentum components o…
Structure of the electromagnetic field around the free electron in nonrelativistic QED.
1991
We study, within the framework of nonrelativistic QED, the structure of the electromagnetic field in the neighborhood of a free spinless electron dressed by the interaction with the vacuum field. We introduce a suitable formalism that correlates electron position and field operators. The quantum average value obtained by applying correlated field operator to the dressed state gives the average value of the corresponding field quantity as a function of distance from the electron. The results obtained separately for the electric- and magnetic-field energy density around the particle display contributions that have quantum origin and that cancel in summing of the two, yielding the total energy…
Utilització d'una eina online per a la realització de tutories remotes: una experiència pràctica
2010
Elluminate Live! és un producte comercial dissenyat específicament per a la impartició de classes virtuals i la vídeo conferència entre múltiples usuaris. En aquest article, vam analitzar el seu ús en el context de la realització de tutories remotes en l'assignatura Informàtica, de primer curs de la titulació de Llicenciatura en Matemàtiques en la Universitat de València. A més de constituir una alternativa viable com complement a les tutories presencials, l'ús de l'eina proporciona una sèrie d'avantatges pel que fa a aquestes. Entre elles destaca la possibilitat de supervisar el treball de diversos alumnes de forma simultània, de realitzar explicacions a grups i de facilitar el treball coo…
Utilización de una herramienta online para la realización de tutorías remotas: una experiencia práctica
2010
La plataforma Elluminate Live! es un producto comercial diseñado específicamente para la impartición de clases virtuales y la video conferencia entre múltiples usuarios. En este artículo, analizamos su uso en el contexto de la realización de tutorías remotas en la asignatura “Informática”, de primer curso de la titulación de Licenciatura en Matemáticas en la Universidad de Valencia. Además de constituir una alternativa viable como complemento a las tutorías presenciales, el uso de la herramienta proporciona una serie de ventajas con respecto a éstas. Entre ellas destaca la posibilidad de supervisar el trabajo de varios alumnos de forma simultánea, de realizar explicaciones a grupos y de fac…
Making interaction with virtual reality accessible : rendering and guiding methods for subtitles
2021
AbstractAccessibility in immersive media is a relevant research topic, still in its infancy. This article explores the appropriateness of two rendering modes (fixed-positioned and always-visible) and two guiding methods (arrows and auto-positioning) for subtitles in 360° video. All considered conditions have been implemented and integrated in an end-to-end platform (from production to consumption) for their validation and evaluation. A pilot study with end users has been conducted with the goals of determining the preferred options by users, the options that result in a higher presence, and of gathering extra valuable feedback from the end users. The obtained results reflect that, for the c…
Segmentation and Navigation Support of Clinical Data Sets to Simulate the Bronchoscopy and Rhinoscopy
2007
A training and simulation system for therapy planning is developed based on patient specific imaging data. A real endoscope is used for navigation through the virtual patient. For this purpose sensors were built in the endoscope in order to track the translation, rotation and the angle of the distal end. Pre-processing (segmentation, tissue characterization) speeds-up the volume rendering up to real-time. Collision detection enables a realistic fly through the virtual patient.
Ophthalmic: Laboratorio virtual para el diseño de nuevas lentes oftálmicas
2013
This work presents a new virtual laboratory, OPHTALMIC, developed with MATLAB GUI for using in Optics and Optometry courses as a computer tool for studying the focusing properties of multifocal diffractive both on unconventional structures both periodic and aperiodic. This virtual laboratory enables students to quickly and easily analyze the influence of the different parameters of construction and find the best solution for a user.
Virtual prototyping of a new intramedullary nail for tibial fractures
2012
In this work a new distal interlocking system has been developed which is easy to use, allows a reduction of the operating time and consequently the exposure to radiations both for surgeon and patient. The main goal of this study has been the design of a new intramedullary nail for tibial fractures able to simplify and speed up the distal locking operation phases. After a preliminary stage during which several candidate concepts have been proposed and analysed, the best solution has been developed and deeply investigated. The new system, called “expansion nail”, has been firstly modelled by setting up a full parametric CAD model and, then, tested by running non linear FEM analyses to evalua…
CNC Milling Machine Simulation in Engineering Education
2012
In this work an effective simulator for a CNC milling machine is presented. It has been developed in EMC2, a free Opens Source NC software running in Linux environment, developed by an international community. It can be installed on a common PC and is able to: control a CNC machine; read part programs; display the tool path; send instructions to the CNC machine for the cutting process. In this work a new feature has been implemented, which can both display a 3D model of the machine and simulate all the motions of the movable parts of a real 3 axis end milling machine. This simulator lets the users not only verify the toolpath but also detect any possible collision by using the very computer…
An Indo-French Virtual University Project
2016
Indo-French cooperation has existed for several decades, and has flourished in the recent period, with a number of flagship programmes and cross-border schemes in science, technology and management. Virtual universities refer to both conventional campus-based (hybrid and brick-and-mortar) universities offering online courses, and purely virtual universities with all their activities delivered online via the Internet. A virtual university is involved as a direct provider of learning opportunities and uses the Internet to deliver its programmes and courses while receiving tuition support. We propose in this ultimate chapter an innovative architecture for an Indo-French knowledge management sy…