Valledupar, Colombia
Valledupar, Colombia

The Popular University of Cesar , is a public, departmental, coeducational university based primarily in the city of Valledupar, Cesar, Colombia. Wikipedia.


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Diaz L.,Popular University of Cesar | Reales J.,Popular University of Cesar | Torres C.,Popular University of Cesar
Journal of Physics: Conference Series | Year: 2017

In Colombia, especially in the Atlantic Coast it is produced and marketed the costeño cheese, an indigenous product of the gastronomy of this region, but the prolonged exposure of this product to the environment leads to microbial contamination and non-enzymatic rancidity. For this reason the transmittance of an edible coating based in aloe vera gel and cassava starch to preserve costeño cheese was evaluated using trifurcated optical fibers. The results become a tool for the selection of treatments in making edible films and their subsequent use in coatings for various types of food products. © Published under licence by IOP Publishing Ltd.


Avila D.A.,Popular University of Cesar | Horta S.D.,Popular University of Cesar | Torres C.O.,Popular University of Cesar
Journal of Physics: Conference Series | Year: 2017

In this work we studied experimentally the performance of an solid bottle optical resonator made of PMMA (polymethylmethacrylate) for measure the relative humidity of the medium. In the developed device, the WGMs modes within the microcavity are excited by the proximity of an optical fiber taper with an outer diameter of the order of 3-5 microns made from stretching a standard optical fiber of Silica by the flame brushing technique. In the resonant device, the field produced by a laser system tunable TLS is guided through the fiber taper and is coupled into the microcavity by the approach of the fiber taper to the equatorial zone of the microbottle, causing the excitation of the WGMs resonant modes inside the same. When the device is subjected to changes in relative humidity of the medium, the wavelengths of resonance of WGMs modes that have been coupled in the microresonator are shifted spectrally depending on the external humidity, showing an experimental sensitivity in the resonator due to changes in the relative humidity of the medium. In the experiment, it was possible to produce different samples of optical resonators with a profile shaped bottle with different maximum diameters achieving a maximum sensitivity of 0.032 nm/% RH for a resonator with equatorial diameter of 1250 μm. © Published under licence by IOP Publishing Ltd.


Perez R.,University of La Guajira | Vilardy J.M.,University of La Guajira | Torres C.O.,Popular University of Cesar
Journal of Physics: Conference Series | Year: 2017

Information security with optical processing, such as the double random phase encoding and the Gabor transform (GT) has been investigated by various researchers. We present a two-dimensional (2-D) generalization of the one-dimensional GT. This 2-D GT is applied to encrypt digital images in this paper. The scaling factors of the GT can be used as new keys, providing a new encryption system with a high security characteristics. This method can encrypt and protect the information of the digital images with a high security for information processing systems. © Published under licence by IOP Publishing Ltd.


Vilardy J.M.,Popular University of Cesar | Jimenez C.J.,University of La Guajira | Torres R.,Popular University of Cesar
Journal of Physics: Conference Series | Year: 2017

We show the design and implementation of an optical polarimeter using electronic control. The polarimeter has a software with a graphical user interface (GUI) that controls the optoelectronic setup and captures the optical intensity measurement, and finally, this software evaluates the Stokes vector of a state of polarization (SOP) by means of the synchronous detection of optical waves. The proposed optoelectronic polarimeter can determine the Stokes vector of a SOP in a rapid and efficient way. Using the polarimeter proposed in this paper, the students will be able to observe (in an optical bench) and understand the different interactions of the SOP when the optical waves pass through to the linear polarizers and retarder waves plates. The polarimeter prototype could be used as a main tool for the students in order to learn the theory and experimental aspects of the SOP for optical waves via the Stokes vector measurement. The proposed polarimeter controlled by a GUI of Matlab is more attractive and suitable to teach and to learn the polarization of optical waves. © Published under licence by IOP Publishing Ltd.


Avila Padilla D.A.,Popular University of Cesar | Torres Moreno C.O.,Popular University of Cesar | Cordeiro C.M.B.,University of Campinas
Journal of Physics: Conference Series | Year: 2017

This paper studied experimentally the behavior of a capillary microresonator made from PMMA polymer as a sensor for measuring relative humidity. In the manufactured device, the WGMs modes within the microcavity are excited by the proximity of an optical fiber Taper made from the stretching of a standard optical fiber of silica by the method of scanning flame with waist of the order of 3-5 μm. In the device, the field from a tunable laser system TLS is coupled into the capillary along its cross section where the resonant modes were observed WGMs into the cavity. When the system is subjected to change of the relative humidity of the external environment, the wavelengths of peaks resonances of WGMS modes of the resonant system experience a spectral shift, so that a sensitivity of the microresonator is observed at changes in humidity of the external environment. During the experiment, it was manufactured capillaries with different diameters and different wall thickness obtaining a sensitivity of the order of 0.07 nm/% RH for a capillary thickness 42.1 μm. © Published under licence by IOP Publishing Ltd.


Tapias O.L.,Popular University of Cesar | Salinas S.A.,Pontifical Bolivarian University
2016 Global Medical Engineering Physics Exchanges/Pan American Health Care Exchanges, GMEPE/PAHCE 2016 | Year: 2016

A toolholder robot is proposed for laparoscopy using a Novint Falcon haptic interface, adapted to a laparoscopic forceps through a system of passive joints; this article describes the direct and inverse kinematics for both the interface as well as for the passive joints that form the robot model. The simulation allows to observe that the system maintains a pivotal movement in a Cartesian point of incision, and it is verified that the workspace of the robot will allow conducting training exercises in a simulated abdomen. © 2016 IEEE.


Jimenez C.,University of La Guajira | Torres C.,Popular University of Cesar | Mattos L.,Popular University of Cesar
Journal of Physics: Conference Series | Year: 2011

A new method for image encryption is introduced on the basis of two-dimensional (2-D) generalization of 1-D fractional Hartley transform that has been redefined recently in search of its inverse transform We encrypt the image by two fractional orders and random phase codes. It has an advantage over Hartley transform, for its fractional orders can also be used as addictional keys, and that, of course, strengthens image security. Only when all of these keys are correct, can the image be well decrypted. Computer simulations are also perfomed to confirm the possibilty of proposed method.


Gouveia M.A.,University of Campinas | Avila P.D.,University of Campinas | Avila P.D.,Popular University of Cesar | Marques T.H.R.,University of Campinas | And 2 more authors.
Optics Express | Year: 2015

A hydrostatic pressure sensor based on morphology dependent resonances in a polymeric tube is presented. By internal pressurization, normal tensions will increase the device's size and shrink its wall thickness, inducing a shift in the resonant wavelengths of the resonator. Numerical simulations indicate that there are two modal regimes of sensitivity and a maximum achievable sensitivity, related to the device's geometry, constitutive material and analysed mode order. A sensitivity as high as 0.36 ± 0.01 nm/bar has been experimentally found for a 1.8mm diameter PMMA tube with wall thickness of 80μm. © 2015 Optical Society of America.


Vega F.,Popular University of Cesar | Torres C.,Popular University of Cesar
Journal of Physics: Conference Series | Year: 2015

In this paper we show the design and implementation of a system to capture and analysis of dynamic speckle. The device consists of a USB camera, an isolated system lights for imaging, a laser pointer 633 nm 10 mw as coherent light source, a diffuser and a laptop for processing video. The equipment enables the acquisition and storage of video, also calculated of different descriptors of statistical analysis (vector global accumulation of activity, activity matrix accumulation, cross-correlation vector, autocorrelation coefficient, matrix Fujji etc.). The equipment is designed so that it can be taken directly to the site where the sample for biological study and is currently being used in research projects within the group. © Published under licence by IOP Publishing Ltd.


Carrasquilla R.J.,Popular University of Cesar | Neira O.L.,Popular University of Cesar
Journal of Physics: Conference Series | Year: 2011

Time dependent density functional (TD-DFT) calculations were performed on 1,3-benzoxazole and substituted benzoxazoles using the B3LYP functional and the 6-31+G(d) basis sets. The geometry of the S0 and S1 singlet ground and excited states were optimized in gas phase, toluene and methanol using B3LYP/6-31+G(d) y CIS/6-31+G(d) methods, respectively, and the vertical π → π* absorption largest wavelength transitions were determined. Several global molecular descriptors were considered such as the hardness, chemical potential, electronegativity and the dipole moment for each molecule and was determined the influence that has, about the values of these descriptors, the alteration of the main molecular chain of an initial structure (1,3 not substituted Benzoxazole). Generally, the predicted spectra are in agreement with the experimental data.

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