Diseño de un robot antropomórfico de propósito general

En este documento de consigna el proceso de ingeniería inversa realizado al brazo robótico Kawazaki RS03N existente en los laboratorios de mecatrónica, de la Universidad Tecnológica de Pereira. Se describe el proceso de desarrollo de cada una de las partes del robot, con la ayuda de un software CAD y como este permite la obtención de los parámetros necesarios para el análisis tanto cinemático como dinámico el sistema. Se determina la cinemática directa del robot a través del método Denavit-Hartenberg, para con la ayuda del robotics toolbox de matlab realizar el estudio dinámico del sistema. Finalmente se desarrolla una interfaz de interacción con el robot ,con la ayuda de una GUI, que permitirá una interacción sencilla con el brazo robótico

3D-Mesomechanical analysis of cracking and spalling of concrete subject to high temperatures

In this paper, an existing meso-structural model for concrete which had been applied to the study of the mechanical effects of high temperatures in 2D, is extended to 3D, and to more complex coupled thermo-mechanical analysis. The material is idealized as a twophase compositein which all mesh lines (or surfaces in 3D) are potential cracks equipped with fracture-based zero-thickness interface elements. Different thermal expansion laws are assumed for matrix and particles, whereby the deformation mismatch can generate cracking. Temperature distributions are obtained from a separate thermal diffusionanalysis.The thermal analysis is first assumed uncoupled, but then also coupled with the mechanical analysis, as the layers of material spalloff and the boundary conditionsare moved to the new domain boundaries. The new computational results in 3D are compared to basic experimental observations reported in the literature and to the previous computational results obtained in 2D

Non-extensive radiobiology

The expression of survival factors for radiation damaged cells is based on probabilistic assumptions and experimentally fitted for each tumor, radiation and conditions. Here we show how the simplest of these radiobiological models can be derived from the maximum entropy principle of the classical Boltzmann-Gibbs expression. We extend this derivation using the Tsallis entropy and a cutoff hypothesis, motivated by clinical observations. A generalization of the exponential, the logarithm and the product to a non-extensive framework, provides a simple formula for the survival fraction corresponding to the application of several radiation doses on a living tissue. The obtained expression shows a remarkable agreement with the experimental data found in the literature, also providing a new interpretation of some of the parameters introduced anew. It is also shown how the presented formalism may has direct application in radiotherapy treatment optimization through the definition of the potential effect difference, simply calculated between the tumour and the surrounding tissue.Comment: 8 pages, 1 figure. Sent to MaxEnt 2010. To be submitted for publicatio

PID - Gain Scheduling Controller for a Robot Manipulator

This paper presents the implementation of an adaptive PD - Gain Scheduling controller for a six-degree-of-freedom robot manipulator. Uncoupled PD controllers are proposed for each joint where each single manipulator joint is controlled independently of the others. The gain scheduling technique enables the controller to adapt on-line the PD parameters depending on the operation conditions (essentially the robot arm position). The nonlinear dynamic model of the robot arm is then linearized discarding non-linear terms which are considered as model uncertainties, and a continuous adaptation law for the PD controller parameters is proposed. The overall control strategy can be regarded as composed by a non-linear transformation (adaptation law), followed by a linear PD regulator. This simple technique offers promising results with respect to the traditional worst-case PD design.Ministerio de Ciencia y Tecnología TAP98-054

Gestión bajo demanda de laboratorios informáticos universitarios

La infraestructura “Virtual Lab” propuesta se presenta como una mejora en la gestión energética de los laboratorios informáticos, una simplificación del mantenimiento de los puestos sobre los que los alumnos realizan sus prácticas y un aumento de las posibilidades que los laboratorios pueden ofrecer a sus alumnos. “Virtual Lab”, gracias a la virtualización permite desacoplar el software de los equipos hardware lo que permitiría mejorar el aprovechamiento energético de los laboratorios universitarios, al permitir tener abiertos y en funcionamiento exclusivamente un número determinado de puestos que ofrecerían todas las posibles configuraciones. “Vlab” permite a los alumnos trabajar con estructuras complejas, como clusters de computadoras; acceder remotamente desde sus casas para realizar prácticas sobre los puestos de laboratorios de la universidad; incluso, si las licencias de software lo permiten, se podría poner a disposición de los alumnos las imágenes de las Máquinas Virtuales, con lo que la reproducción de la configuración del laboratorio en sus casas sería automática. [ABSTRACT] The “Virtual Lab” infraestructure is presented as an improve in energetic management of computer laboratories, a simplification of the students working systems's manteinance and an increase of the posibilities the laboratories can offer to them. “Virtual Lab” uses virtualization to decouple the software from the hardware in order to improve the energetic utilization of university laboratories, allowing to keep open and working exclusively a determined number of computers that will offer all possible configurations. “Vlab” allows students work with complex structures, as computer clusters; remote access from their home to laboratory systems to do practices; and also, if software licences allows it, it could be possible to give the students the Virtual Machines images, so they could use the laboratory configuration in their homes

Multi-layered solid-PCM thermocline thermal storage concept for CSP plants. Numerical analysis and perspectives

Thermocline storage concept has been considered for more than a decade as a possible solution to reduce the huge cost of the storage system in concentrated solar power (CSP) plants. However, one of the drawbacks of this concept is the decrease in its performance throughout the time. The objective of this paper is to present a new thermocline-like storage concept, which aims at circumventing this issue. The proposed concept consists of a storage tank filled with a combination of solid material and encapsulated PCMs, forming a multi-layered packed bed, with molten salt as the heat transfer fluid. The performance evaluation of each of the prototypes proposed is virtually tested by means of a detailed numerical methodology which considers the heat transfer and fluid dynamics phenomena present in these devices. The virtual tests carried out are designed so as to take into account several charging and discharging cycles until periodic state is achieved, i.e. when the same amount of energy is stored/released in consecutive charging/discharging cycles. As a result, the dependence of the storage capacity on the PCMs temperatures, the total energy and exergy stored/released, as well as the efficiencies of the storing process are compared for the different thermocline, single PCM, cascaded PCM and the proposed multi-layered solid-PCM (MLSPCM) configurations. The analysis shows that the multi-layered solid-PCM concept is a promising alternative for thermal storage in CSP plants.Peer ReviewedPostprint (author’s final draft

Techno-economic performance evaluation of solar tower plants with integrated multilayered PCM thermocline thermal energy storage: a comparative study to conventional two-tank storage systems

Copyright 2016 AIP Publishing. This article may be downloaded for personal use only. Any other use requires prior permission of the author and AIP Publishing.Solar Tower Power Plants with thermal energy storage are a promising technology for dispatchable renewable energy in the near future. Storage integration makes possible to shift the electricity production to more profitable peak hours. Usually two tanks are used to store cold and hot fluids, but this means both higher investment costs and difficulties during the operation of the variable volume tanks. Instead, another solution can be a single tank thermocline storage in a multi-layered configuration. In such tank both latent and sensible fillers are employed to decrease the related cost up to 30% and maintain high efficiencies. This paper analyses a multi-layered solid PCM storage tank concept for solar tower applications, and describes a comprehensive methodology to determine under which market structures such devices can outperform the more conventional two tank storage systems. A detail model of the tank has been developed and introduced in an existing techno-economic tool developed by the authors (DYESOPT). The results show that under current cost estimates and technical limitations the multi-layered solid PCM storage concept is a better solution when peaking operating strategies are desired, as it is the case for the two-tier South African tariff scheme.Peer ReviewedPostprint (published version

Econofísica: En busca de un caballo perfectamente esférico y de masa despreciable

En este artículo, se analiza a través de símiles históricos el estado de la contribución de la Física a la Economía. Para ello se hace un repaso del modo de funcionamiento de la Física, o mejor dicho, del modo de proceder de los físicos. Ésta es la principal aportación de una ciencia a la otra: una forma diferente de aproximarse a los problemas complejos a los enfrenta la economía. En la discusión planteamos, de estos problemas, los que consideramos llevan a cabo mediante sistemas informatizados, y la necesidad de, llegado al grado de complejidad que tienen tanto la economía como la ciencia económica en la actualidad, una necesaria revolución en la forma de “mirar” de los economistas. Con ello proponemos que lo que se necesita en Economía es lo que tantas veces se ha buscado (y encontrado) en física: un modelo o una serie de modelos muy sencillos que capten, de manera totalmente nueva, la “esencia” del problema. Este modelo, el caballo esférico de masa despreciable, aunque erróneo (como los anteriores), será úti