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Zimmerman R.D.,Cornell University | Murillo-Sanchez C.E.,Autonomous University of Manizales | Murillo-Sanchez C.E.,National University of Colombia | Thomas R.J.,Cornell University
IEEE Transactions on Power Systems | Year: 2011

Matpower is an open-source Matlab-based power system simulation package that provides a high-level set of power flow, optimal power flow (OPF), and other tools targeted toward researchers, educators, and students. The OPF architecture is designed to be extensible, making it easy to add user-defined variables, costs, and constraints to the standard OPF problem. This paper presents the details of the network modeling and problem formulations used by Matpower, including its extensible OPF architecture. This structure is used internally to implement several extensions to the standard OPF problem, including piece-wise linear cost functions, dispatchable loads, generator capability curves, and branch angle difference limits. Simulation results are presented for a number of test cases comparing the performance of several available OPF solvers and demonstrating Matpower's ability to solve large-scale AC and DC OPF problems. © 2010 IEEE.

Agency: Cordis | Branch: FP7 | Program: CSA | Phase: ICT-2011.3.4 | Award Amount: 466.09K | Year: 2011

The RISC project aims at deepening strategic R&D cooperation between Europe (EU) and Latin America (LA) in the field of High Performance Computing (HPC) by building a multinational and multi-stakeholder community that will involve a significant representation of the relevant HPC R&D EU and LA actors (researchers, policy makers, users). RISC will identify common needs, research issues and opportunities for cooperative R&D on HPC between EU and LA in the transition to multi-core architectures across the computing spectrum and relevant programming paradigms, algorithms and modelling approaches, thus setting the basis for the formulation of a global strategy for future research. The project will achieve its overall aim via a range of activities: 1. Assessing the ICT collaboration potential in the High Performance Computing and Computational Science area for the two regions; producing a Green Paper on High Performance Computing Drivers and Needs in Latin America; mapping the LA HPC actors and trends; identifying the opportunities for LA ICT actors in the EU and for EU HPC actors in LA; aligning EU and LA HPC policies and strategies; 2. Sharing and disseminating information and results in the focus area of EU HPC to a number of research, policy and practice actors dealing with technology applications in the LA region; making available existing Latin American HPC research to EU research, policy and practice actors;\n3.\tOrganising awareness-raising events about the ECs ICT R&D programmes, in particular those ones relevant to HPC and exascale computing for LA HPC actors. Organising Summer Schools and Advanced Workshops between EU and LA ICT actors to inform and initiate research collaborations between them. Networking, capacity building and training components of these events will enhance the impact 4. Actively engaging the relevant industry by focusing on industrial problems and problems with impact for the society. Providing advanced support services to a selected number of competent Latin American ICT actors to build long-term relationships with key EU counterparts. The target areas are: Innovation and HPC and its impact, Mathematical Models enhancing HPC and key areas such as Life Sciences, Climate Change, Financial Modelling etc with the corresponding research clusters concentrated around these areas.\n5.\tExtending HPC with links and relationships with complementary technology and tools in the areas of virtualization, data visualization, data analysis and simulation, aligned with industrial-driven application fields, creating a value chain for final users and practitioners. 6. Enhancing HPC R&D policy dialogue between policy makers and stakeholders from EU and Latin American HPC communities; develop a Road Map towards a Joint Strategy in HPC R&D. At the end of the project we expect a fully functioning network focusing on activities to support and to promote coordination of the HPC and Computational Science research between EU and LA.

Objective. To determine the appearance and concurrent validity of an instrument to assess dis- ability in people with chronic spinal cord injury (SCI-DAS) based on the ICF Core Set. Method: There was a total of 100 Colombians from four cities who had spinal cord injury for more than six months. Also, eight physical therapists that had average professional experience of more than 6.75 years participated in this study. Appearance validity was assessed through a focus group and a survey of observers, we calculated the items variation coefficients and the relevance and appropriateness index. Concurrent validity was analyzed with AIS (American Spinal Injury As- sociation [ASIA] Impairment Scale) and Disability Scale WHO-DAS II, using the Spearman cor- relation coefficient. Results. The overall relevance and adequacy of the instrument yielded a mean of 4.83/5 and 4.48/5 with a variation coefficient of 0.03. The agreement index among observers for good and excellent ratings was of 0.96 for relevance and of 0.86 for adequacy. The disability measured by the SCI-DAS showed a moderate significant correlation with the neurological level, the AIS motor and sensory indices, and a high one with disability measured by the WHO-DAS II (p<0. 001). A marginal statistically low-level correlation of functional compromise scale AIS (p = 0. 052) was found. Conclusions. In general, a good appearance validity of the instrument (SCI-DAS) was found. The concurrent validity of the instrument (SCI-DAS) with the impairment scale AIS and with the Disability Scale-WHO-DAS II was also evidenced.

Alba-Castro M.,Autonomous University of Manizales
2014 9th Computing Colombian Conference, 9CCC 2014 | Year: 2014

Non-interference is a semantic program property that assigns confidentiality levels to data objects and prevents illicit information flows from high to low security levels. In this paper, we extend a certification technique for confidentiality of Java classes regarding non-interference, in order to consider objects and object aliasing. The technique is based on rewriting logic, which is efficiently implemented in the high-level programming language Maude. Starting from a previous Java abstract semantics specification written in Maude, we develop an information flow sensitive Java semantics that allows us to observe global non-interference properties, with object aliasing. In order to achieve a finite state transition system, we develop an abstract Java semantics that we use for secure and effective confidentiality analysis. We have implemented our methodology and developed some experiments that demonstrate the feasibility of our approach. © 2014 IEEE.

Tinoco H.A.,Autonomous University of Manizales
International Journal of Modeling, Simulation, and Scientific Computing | Year: 2016

In this study, a numerical approach is established to design a beam coupled to a Voice Coil Motor (VCM) with the aim to maximize the displacement in the inductive transducer. A finite element model is developed to simulate a VCM with different beams applying a harmonic analysis. The VCM is extracted from a recycled hard disk drive (HDD) and a parametric modal analysis is performed to identify the material parameters of the HDD and the beam. These parameters are obtained comparing the real vibration modes and natural frequencies (VCM-beam) with those determined from the finite element model. A numerical-experimental case study is carried out to demonstrate that if a beam is designed for a specific low frequency vibration between 0 and 10Hz, the displacements are maximized in the VCM. For this purpose, real acceleration measurements taken from three individuals are used to provide the vibration signals in the numerical model. A beam is designed for one of the individuals using the natural frequency values determined from the measured signals. Results show that the displacements are maximized in the model which coincides with the natural frequency of the chosen individual. The main purpose of this research is to establish a design tool for energy harvesting purposes with VCM based on low frequency vibration sources as for example gait motions. © 2016 World Scientific Publishing Company.

Matas J.,University of Barcelona | Castilla M.,University of Barcelona | De Vicuna L.G.,University of Barcelona | Miret J.,University of Barcelona | And 2 more authors.
IEEE Transactions on Power Electronics | Year: 2010

This paper explores the impact of the output impedance on the active and reactive power flows between parallelized inverters operating with the droop method. In these systems, a virtual output impedance is usually added to the control loop of each inverter to improve the reactive power sharing, regardless of line-impedance unbalances and the sharing of nonlinear loads. The virtual impedance is usually implemented as the time derivative of the inverter output current, which makes the system highly sensitive to the output current noise and to nonlinear loads with high slew rate. To solve this, a second-order general-integrator (SOGI) scheme is proposed to implement the virtual impedance, which is less sensitive to the output current noise, avoids to perform the time derivative function, achieves better output-voltage total harmonic distortion, and enhances the sharing of nonlinear loads. Experimental results with two 2-kVA inverter systems under linear and nonlinear loads are provided to validate this approach. © 2010 IEEE.

Thomson F.,Autonomous University of Manizales
Journal of Agrarian Change | Year: 2011

This article examines connections between Colombia's internal armed conflict and agrarian questions. It pays attention to the country's specific historical trajectory of agrarian change, the violent expression of social tensions that this elicited, and the particular ways in which these dynamics were influenced by a changing global context. This analysis of the intimate ties between violent conflict and agrarian questions in Colombia, both in terms of their historical development and their contemporary manifestations, challenges popular notions of the relationship between armed conflict and development. In particular, the article contributes to a critique of the conventional version of the conflict-development nexus by illustrating ways in which the experience of capitalist development in Colombia has been violent and produced poverty. © 2011 Blackwell Publishing Ltd.

Duque Parra J.E.,University of Caldas | Duque Parra J.E.,Autonomous University of Manizales
International Journal of Morphology | Year: 2012

SUMMARY: A marked cavitation in the septum pellucidum level is reported, a great cavum septum pellucidum of an adult in the closed space generally recognized as the central nervous system, which is evident in itself, at certain stages of intrauterine life. This cavitation is usually absent in the healthy adult, but in some people with schizophrenia and pugilistic dementia, the cavity can be regarded and found relatively frequently. This finding was found randomly in one of forty-two adult brains, superficially valued from the gross anatomy as normal. This finding may be associated with behavioral disorders, taking in to account that the brain corresponded to a person from a psychiatric hospital.

Tinoco H.A.,Autonomous University of Manizales
Structural and Multidisciplinary Optimization | Year: 2016

This study presents a numerical procedure for the analysis of reinforced concrete slabs (RCS) that obey Nielsen’s yield criterion. A pseudo lower bound formulation of finite elements is established to solve the static theorem as a conic optimization problem with the aim to determine the maximum load capacity of RCS. Lower bound solution is improved by means of an adaptive remeshing strategy using a dissipation estimator which is obtained on the normalization of the kinematic criterion defined from the yield criteria. Different known examples are evaluated and the results show a good agreement with the exact values of the collapse load as well as numerical convergence. The displacement rates are estimated from the dual solution established in the optimization problem in order to determine the collapse mechanism in the slab. © 2016 Springer-Verlag Berlin Heidelberg

Rodriguez-Sotelo J.L.,Autonomous University of Manizales | Peluffo-Ordonez D.,National University of Colombia | Cuesta-Frau D.,Polytechnic University of Valencia | Castellanos-Dominguez G.,National University of Colombia
Computer Methods and Programs in Biomedicine | Year: 2012

The computer-assisted analysis of biomedical records has become an essential tool in clinical settings. However, current devices provide a growing amount of data that often exceeds the processing capacity of normal computers. As this amount of information rises, new demands for more efficient data extracting methods appear.This paper addresses the task of data mining in physiological records using a feature selection scheme. An unsupervised method based on relevance analysis is described. This scheme uses a least-squares optimization of the input feature matrix in a single iteration. The output of the algorithm is a feature weighting vector.The performance of the method was assessed using a heartbeat clustering test on real ECG records. The quantitative cluster validity measures yielded a correctly classified heartbeat rate of 98.69% (specificity), 85.88% (sensitivity) and 95.04% (general clustering performance), which is even higher than the performance achieved by other similar ECG clustering studies. The number of features was reduced on average from 100 to 18, and the temporal cost was a 43% lower than in previous ECG clustering schemes. © 2012 Elsevier Ireland Ltd.

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