Time filter

Source Type

Rueda E.,University of Antioquia | Muneton D.,University of Antioquia | Muneton D.,CONICET | Gomez J.A.,Jaime Isaza Cadavid Colombian Polytechnic | And 2 more authors.
Optics Letters | Year: 2013

In the present work, we propose a method to generate high-quality optical vortices with a reduced number of phase levels by using multilevel vortex-producing lenses (VPLs). The VPL is implemented in a liquid-crystal spatial light modulator with limited capacity to project phase levels. The proposed method significantly improves the quality of the optical vortex obtained by employing spiral phase plates with the same number of phase levels. Simulations and experimental results confirming the effectiveness of the method are presented. © 2013 Optical Society of America.


Mateus S.,Jaime Isaza Cadavid Colombian Polytechnic | Branch J.,National University of Colombia
Communications in Computer and Information Science | Year: 2015

In this article, two artificial intelligence techniques such as Artificial Neural Networks and Genetic Algorithms were incorporated into a 3D working environment and turned into a game engine, which simulates a working environment in order to obtain possible warning signs to different hazards. These techniques were incorporated in the perception and reasoning of a character in the virtual environment, in order to react intelligently to given warning signs. © Springer International Publishing Switzerland 2015.


Mateus S.,Jaime Isaza Cadavid Colombian Polytechnic | Branch J.,National University of Colombia
Lecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics) | Year: 2016

This paper describes a Virtual Environment with Intelligent Agents, using an agent-oriented methodology called Prometheus. This technique was incorporated in the perception and reasoning of a character in the Intelligent Virtual Environment (IVE), in order to react intelligently to given warning signs. The main objective of the character in the developed IVE is finding the optimum path without having to do extra shifts. The used technique achieves an optimal solution using only probability calculations, without requiring additional data to be supplied. This solution is obtained given the repetitions and the number of ants in the character agent. The virtual environment was created with the UDK tool to identify warning signs in a work environment. UDK is used because of its importance in the development of world-renowned games. © Springer International Publishing Switzerland 2016.


Fuertes J.L.,Technical University of Madrid | Gonzalez L.F.,Jaime Isaza Cadavid Colombian Polytechnic | Martinez L.,Technical University of Madrid
Lecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics) | Year: 2016

Computer programmers with dyslexia can be found in a range of academic and professional scenarios. Dyslexia may have the effect on a computer programmer of degrading the expected results during collaborative software development. These people may perform better using visual programming languages. However, we need to understand what programmers with dyslexia experience in order to be able to come up with possible solutions. We have conducted an analysis of existing literature and a survey on dyslexia and programming. This paper reports the preliminary results based on the data gathered so far and the key characteristics and needs of this group with the aim of defining the profile of computer programmers with dyslexia. © Springer International Publishing Switzerland 2016.


Henao R. J.L.,Jaime Isaza Cadavid Colombian Polytechnic | Espinosa O J.E.,Jaime Isaza Cadavid Colombian Polytechnic
Proceedings - International Carnahan Conference on Security Technology | Year: 2014

The intrusion in data networks, are a constant problem faced by networks administrators. Because of this, it is necessary identify, study and propose techniques to detect the moment in which the network is attacked, with the purpose of take measures to mitigate these threats. In this paper was conducted a study of the threats taxonomy that could lead to an attack in a data network. For this, we have identified the most relevant characteristics of the network traffic in order to be processed and classified using machine learning techniques, specifically the normalization (Z-Score), dimensionality reduction (PCA) and classification based on artificial neural networks (ANN) to suggest an intrusion detection system (IDS). © 2013 IEEE.


Gomez J.A.,Pontifical Bolivarian University | Gomez J.A.,Jaime Isaza Cadavid Colombian Polytechnic | Lorduy G. H.,Pontifical Bolivarian University | Salazar A.,Pontifical Bolivarian University
Optics Communications | Year: 2011

In this work, the dependence on the speckle size in the performance of a micro displacement sensor based on fiber specklegrams stored in a photorefractive BSO (Bi 12SiO 20) crystal is experimentally demonstrated. In our experimental setup, a plastic optical fiber (POF) was used to generate a subjective speckle pattern which was recorded in the crystal by using a four-wave mixing arrangement in transmission geometry. The speckle size was controlled by modifying the diameter of a pupil aperture adjacent to a lens producing the image of the speckle. The signal speckle beam was mixed into the crystal with two counter propagating pump beams to generate a fourth beam which is proportional to the conjugate of the original speckle beam. Real time fringe patterns were obtained at the output of the system by producing micro displacements of the fiber output end. Increases of the phase conjugation reflectivity and the visibility of the fringe patterns were appreciated when the speckle length was increased by decreasing the pupil aperture diameter. This behavior allowed recovering the autocorrelation functions of fringe patterns associated to micro displacements that initially led to decorrelation, and therefore, to improve the dynamic range of the metrological system. Until the best of our knowledge this is the first report about the influence of the speckle size on fiber specklegrams sensors recorded on photorefractive materials by four-wave mixing. © 2010 Elsevier B.V. All rights reserved.


Gomez J.A.,Jaime Isaza Cadavid Colombian Polytechnic | Gomez H.L.,Pontifical Bolivarian University | Salazar A.,Pontifical Bolivarian University
Optics Communications | Year: 2011

We present a novel procedure based on an improved physical model and a versatile numerical fitting technique, to simultaneously determinate the Debye screening length and electro-optic coefficient using a thick sample of an optically active photorefractive crystal Bi12SiO20 (BSO). For the computation, experimental data of gain vs. grating spacing were obtained by a two-beam coupling arrangement. Unlike former calculation models, in our work, the general expression for the diffraction efficiency in the presence of self-diffraction is considered, and the influence of the optical activity in the coupling parameters is had into account for the calculation of the gain values. The fitting of the experimental data to the predicted theoretical behavior by our model is achieved by finding the closest theoretical curve to a set of data sampled from a spline-smoothed curve of the experimental data. Both, the Debye screening length ls and the electro-optic coefficient r41 are used as fitting parameters by searching in a rather wide range for each one of the parameters, so that, the estimation of their values is obtained in a more reliable and direct way from the same experiment. The calculations are performed in diffusion regimen and the procedure leads to ls = 0.22 μm and r41 = 4.5 × 10-12m/V. Because the optical activity can alter the maximum gain and self-diffraction effects influence the energy exchange, the procedure reveals to be physically appropriated for the simultaneous determination of these physical parameters when thick photorefractive crystals with high optical activity are considered. © 2010 Elsevier B.V. All rights reserved.


Objective. Contribute to the statistical and genotypic characterization (mean, standard error, variance and heritability) of the Total Length (LT) and Height (LAL), and suggest a selection strategy to improve seed quality in broodstock of red tilapia Oreochromis sp. Materials and methods. The project was conducted in the Experimental and Production Fish Farm (PCJIC), one Km from the town of San Jerónimo, 61 Km to the west of Medellín (Antioquia). Three mating groups were formed, eachin proportion of 3 females and 1 male: a mating group of White Females (HB) x Red Male (MR) and two mating groups White Females (HB) x White Male (MB). The offspring were measured at 60 days post hatching, taking into account statistical assumptions. Results. The ANOVA showed that offspring differ significantly (p<0.001) for both continuous variables. The LT was greater for the offspring of HBxMB without reversion (8.04±1.04cm) and LAL was higher for the HBxMR offspring (2.33±0.44cm). The paired correlation between variables was highly significant (r≥0.79, p<0.001). Heritability were 0.59 (LT) and 0.64 (LAL). The dark spot percentages of the offspring were HBxMR (34%) and non-reversed HBxMB (66%). Conclusions. The progeny of Group 1 HBxHR had the better broodstocks for selection by conformation. It is suggested that the number of animals with greater LAL is increased. Additionally, it is important to consider the minor amount of dark spots in broodstock management by independent groups for mass selection.


Dario Gomez N.,Metropolitan Institute of Technology | Gomez J.A.,Jaime Isaza Cadavid Colombian Polytechnic
Optics and Lasers in Engineering | Year: 2013

In this work, a technique to improve the dynamical behavior of a non holographic fiber specklegram sensor for measuring high frequency mechanical perturbations is experimentally demonstrated. In these arrangements, the speckle pattern produced by a multimode optical fiber is coupled to an optical fiber of low numerical aperture, which produces a filtering effect that can be used as optical transduction mechanism. In our proposal, the influence of the speckle size on the sensor performance is evaluated by changes in the numerical aperture of the multimode fiber. A strong effect of the near field fiber speckle size on the reproducibility of the mechanical perturbation is found. The behavior of the reproducibility is evaluated by the calculation of the mean of the variance and the correlation between the mechanical and optical normalized signals. © 2013 Elsevier Ltd.


Gomez J.A.,Jaime Isaza Cadavid Colombian Polytechnic | Salazar A.,Pontifical Bolivarian University
Optics and Lasers in Engineering | Year: 2012

Tuning of the dynamic range of a micro-displacement fiber specklegram sensor based on two-wave mixing on a photorefractive material Bi 12SiO 20 (BSO) and self-correlation operations of speckle patterns is experimentally demonstrated. The high modal interference present in a standard plastic optical fiber (POF) allows generating a Gaussian pattern of subjective speckle, which is recorded in the volume crystal. The volume characteristics of the fiber speckle are changed using a pupil aperture adjacent to the imaging lens of the speckle. A notorious effect of the three dimensional structure of the speckle on the dynamic range of the metrological system is observed, such that, the performance of the sensor can be improved by a simple mechanical action on the pupil aperture. The behavior of the self-correlation loss of the sensor can be adequately described by a squared normalized Bessel function. © 2012 Elsevier Ltd. All rights reserved.

Loading Jaime Isaza Cadavid Colombian Polytechnic collaborators
Loading Jaime Isaza Cadavid Colombian Polytechnic collaborators