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Search Results: 1 - 10 of 54535 matches for " David SALINAS "
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BúSQUEDA DEL CILINDRO NUDOSO EN TROZAS DE PINUS RADIATA D. DON UTILIZANDO IMáGENES DE CT Y PATRONES DE NUDOS
David SALINAS
MADERAS : Ciencia y Tecnología , 2004,
Abstract:
A Case Study of the Learning Styles in Low-Level Learners in a Private School in Bogotá
Abella,David; Salinas,Yakelin;
Profile Issues in Teachers` Professional Development , 2006,
Abstract: this paper aims to report on a study carried out with eighth graders at a private school in bogotá. the main focus of the research was to determine the learning styles characterizing low-achievement students when learning english. it also gives an account of the role learning styles played in the learning process as well as the factors that allowed students to explore their styles. instruments used to collect data were field notes, students’ work and focus-group interviews. considering students’ interests, their needs and providing them with different environments for learning were the silent results of the implementation of this research.
A Case Study of the Learning Styles in Low-Level Learners in a Private School in Bogotá
Abella David,Salinas Yakelin
Profile Issues in Teachers` Professional Development , 2006,
Abstract: This paper aims to report on a study carried out with eighth graders at a private school in Bogotá. The main focus of the research was to determine the learning styles characterizing lowachievement students when learning English. It also gives an account of the role learning styles played in the learning process as well as the factors that allowed students to explore their styles. Instruments used to collect data were field notes, students’ work and focus-group interviews. Considering students’ interests, their needs and providing them with different environments for learning were the silent results of the implementation of this research. Key words: Learning styles, low-achievement learners, learning environments, reinforcement El propósito de este artículo es presentar un estudio que se llevó a cabo con estudiantes de octavo grado en un colegio privado en Bogotá. El objetivo principal de la investigación fue determinar los estilos de aprendizaje que caracterizan a los estudiantes de bajo rendimiento académico cuando aprenden inglés. También dar cuenta del rol que éstos juegan en el proceso de aprendizaje, así como de los factores que les permitían a los estudiantes explorar sus estilos de aprendizaje. Los instrumentos que se emplearon para recolectar datos fueron: notas de campo, trabajos de los estudiantes y entrevistas de grupos focales. Como resultado de la implementación de esta investigación se logró considerar los intereses de los estudiantes y sus necesidades, proporcionándoles diferentes ambientes para el aprendizaje. Palabras claves: Estilos de aprendizaje, estudiantes de bajo rendimiento académico, ambientes de aprendizaje, refuerzo
A Case Study of the Learning Styles in Low-Level Learners in a Private School in Bogotá Un estudio de caso sobre los estilos de aprendizaje de estudiantes de bajo rendimiento académico de un colegio privado en Bogotá
David Abella,Yakelin Salinas
Profile Issues in Teachers` Professional Development , 2006,
Abstract: This paper aims to report on a study carried out with eighth graders at a private school in Bogotá. The main focus of the research was to determine the learning styles characterizing low-achievement students when learning English. It also gives an account of the role learning styles played in the learning process as well as the factors that allowed students to explore their styles. Instruments used to collect data were field notes, students’ work and focus-group interviews. Considering students’ interests, their needs and providing them with different environments for learning were the silent results of the implementation of this research. El propósito de este artículo es presentar un estudio que se llevó a cabo con estudiantes de octavo grado en un colegio privado en Bogotá. El objetivo principal de la investigación fue determinar los estilos de aprendizaje que caracterizan a los estudiantes de bajo rendimiento académico cuando aprenden inglés. También dar cuenta del rol que éstos juegan en el proceso de aprendizaje, así como de los factores que les permitían a los estudiantes explorar sus estilos de aprendizaje. Los instrumentos que se emplearon para recolectar datos fueron: notas de campo, trabajos de los estudiantes y entrevistas de grupos focales. Como resultado de la implementación de esta investigación se logró considerar los intereses de los estudiantes y sus necesidades, proporcionándoles diferentes ambientes para el aprendizaje.
Steimann Pin Repair of Zygomatic Complex Fractures  [PDF]
Jonathan B. Salinas, Darshni Vira, David Hu, David Elashoff, Elliot Abemayor, Maie St. John
International Journal of Otolaryngology and Head & Neck Surgery (IJOHNS) , 2013, DOI: 10.4236/ijohns.2013.22018
Abstract:
Purpose: To present the treatment of zygomaticomaxillary complex (ZMC) fractures with closed-reduction Steinmann-pin fixation and to compare it to the reduction and aesthetic outcomes of open-reduction techniques (ORIF). Materials and Methods: Case series. Charts for 23 patients with ZMC fractures presenting to the Head and Neck Surgery Department at Harbor-UCLA Medical Center from 2005 to 2009 were reviewed. Pre- and post-operative computed tomography (CT) scans were analyzed. Follow up ranged from 3 to 55 months. Interviews were conducted to evaluate the patient’s satisfaction. Patients were placed in two groups: those treated with ORIF and those treated with closed-reduction Steinmann-pin fixation. Results: Twelve patients had complete data for analysis. Average operative time was significantly lower for patients treated with closed-reduction as compared to open-reduction: 65.3 minutes vs. 162.5 minutes (p = 0.02). Bony realignment and aesthetic results were comparable in both groups. Additionally, only one 1cm facial incision was required with this repair system versus several incisions using traditional methods. Conclusions: Closed-reduction Steinmann-pin fixation of ZMC fractures provides adequate bony alignment and aesthetics. Our study supports this system in the repair of ZMC fractures as it requires significantly less operating time, one small incision, and excellent patient outcomes.
VISUALIZACIóN INTERNA DE NUDOS EN ROLLIZOS DE MADERA DE PINUS RADIATA D. DON UTILIZANDO RAYOS-X
Aguilera,Cristhian; Ramos,Mario; Salinas,David;
Maderas. Ciencia y tecnología , 2002, DOI: 10.4067/S0718-221X2002000200010
Abstract: internal structure of wood permits to know different qualities of the raw material. this knowledge can yield utilities up to 10 times for turning one log into optimum wood. differences of density in the structures that compound wood (heartwood, sapwood, knots) make possible that with a computerized tomography, these structures are clearly recognized and differenced. the collection of images from the ct must be treated to see the log as a volume and difference defects in it. volume rendering (vr) allows to generate a 3d image from 2d images. the objective of this article is introduce the progresses in the visualization of knots in logs of pinus radiata d. don grown in chile. for this, 2d images acquired with a x-ray tomograph are used. here, it introduces methods and preliminary results to visualize with vr a commercial diameter log. the results show that it is possible simulate solid of the log and see how the knotty cylinder of the log behaves
VISUALIZACIóN INTERNA DE NUDOS EN ROLLIZOS DE MADERA DE PINUS RADIATA D. DON UTILIZANDO RAYOS-X INTERNAL VISUALIZATION OF KNOTS IN RADIATA PINE LOGS USING X-RAYS
Cristhian Aguilera,Mario Ramos,David Salinas
MADERAS : Ciencia y Tecnología , 2002,
Abstract: Visualizar la estructura interna de las trozas, permite conocer la calidad y destino óptimo de la materia prima, generando ganancias de hasta 10 veces, al identificar el destino de las trozas. Las diferencias de densidad en las estructuras que componen la madera hacen posible que en una Tomografía Computarizada (TC) estas estructuras sean reconocibles y claramente diferenciadas. La colección de imágenes de TC debe ser tratada para poder visualizar el interior de la troza y diferenciar los defectos en esta. El Rendering Volumétrico (RV) nos permite, por otro lado, a partir de una colección de imágenes 2D, generar una visualización del volumen en 3D. El objetivo de este artículo es presentar los avances en la visualización de nudos en trozos de Pinus radiata D. Don crecido en Chile. Para ello se utilizan imágenes tomadas con un tomógrafo de rayos-X. Se presenta aquí la metodología desarrollada para obtener la visualización y los resultados preliminares de la visualización interna. Se realizó un ensayo destructivo en las trozas, obteniéndose índices de exactitud que se contrastaron con la TC y con la reconstrucción hecha por RV. Los resultados indican que es posible disponer de una simulación de la troza y en particular observar como se comporta el cilindro nudoso Internal structure of wood permits to know different qualities of the raw material. This knowledge can yield utilities up to 10 times for turning one log into optimum wood. Differences of density in the structures that compound wood (heartwood, sapwood, knots) make possible that with a Computerized Tomography, these structures are clearly recognized and differenced. The collection of images from the CT must be treated to see the log as a volume and difference defects in it. Volume Rendering (VR) allows to generate a 3D image from 2D images. The objective of this article is introduce the progresses in the visualization of knots in logs of Pinus radiata D. Don grown in Chile. For this, 2D images acquired with a X-Ray tomograph are used. Here, it introduces methods and preliminary results to visualize with VR a commercial diameter log. The results show that it is possible simulate solid of the log and see how the knotty cylinder of the log behaves
Optimal Sensor Placement for Multiple Target Positioning with Range-Only Measurements in Two-Dimensional Scenarios
David Moreno-Salinas,Antonio M. Pascoal,Joaquin Aranda
Sensors , 2013, DOI: 10.3390/s130810674
Abstract: The problem of determining the optimal geometric configuration of a sensor network that will maximize the range-related information available for multiple target positioning is of key importance in a multitude of application scenarios. In this paper, a set of sensors that measures the distances between the targets and each of the receivers is considered, assuming that the range measurements are corrupted by white Gaussian noise, in order to search for the formation that maximizes the accuracy of the target estimates. Using tools from estimation theory and convex optimization, the problem is converted into that of maximizing, by proper choice of the sensor positions, a convex combination of the logarithms of the determinants of the Fisher Information Matrices corresponding to each of the targets in order to determine the sensor configuration that yields the minimum possible covariance of any unbiased target estimator. Analytical and numerical solutions are well defined and it is shown that the optimal configuration of the sensors depends explicitly on the constraints imposed on the sensor configuration, the target positions, and the probabilistic distributions that define the prior uncertainty in each of the target positions. Simulation examples illustrate the key results derived.
Sensor Networks for Optimal Target Localization with Bearings-Only Measurements in Constrained Three-Dimensional Scenarios
David Moreno-Salinas,Antonio Pascoal,Joaquin Aranda
Sensors , 2013, DOI: 10.3390/s130810386
Abstract: In this paper, we address the problem of determining the optimal geometric configuration of an acoustic sensor network that will maximize the angle-related information available for underwater target positioning. In the set-up adopted, a set of autonomous vehicles carries a network of acoustic units that measure the elevation and azimuth angles between a target and each of the receivers on board the vehicles. It is assumed that the angle measurements are corrupted by white Gaussian noise, the variance of which is distance-dependent. Using tools from estimation theory, the problem is converted into that of minimizing, by proper choice of the sensor positions, the trace of the inverse of the Fisher Information Matrix (also called the Cramer-Rao Bound matrix) to determine the sensor configuration that yields the minimum possible covariance of any unbiased target estimator. It is shown that the optimal configuration of the sensors depends explicitly on the intensity of the measurement noise, the constraints imposed on the sensor configuration, the target depth and the probabilistic distribution that defines the prior uncertainty in the target position. Simulation examples illustrate the key results derived.
The confluent algorithm in second order supersymmetric quantum mechanics
David J. Fernandez C.,Encarnacion Salinas-Hernandez
Physics , 2003, DOI: 10.1088/0305-4470/36/10/313
Abstract: The confluent algorithm, a degenerate case of the second order supersymmetric quantum mechanics, is studied. It is shown that the transformation function must asymptotically vanish to induce non-singular final potentials. The technique can be used to create a single level above the initial ground state energy. The method is applied to the free particle, one-soliton well and harmonic oscillator.
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