One-dimensional image reconstruction by exponential filtering in infrared stellar speckle interferometry: application to IRC +10216

Exponential filtering, together with an improved version of the iterative Fourier-transform algorithm, is applied to image reconstruction from one-dimensional infrared stellar speckle interferometry data. The performance of the method is checked first by computer simulations with both noiseless and noisy data and then with a realistic simulation of one-dimensional infrared stellar speckle interferometry. We have seen no problems with convergence. The only problem that we found was an expected noisy appearance of the results when noisy data were simulated. Finally, the method was applied to observational specklegrams of the infrared source IRC +10216, in two standard photometric bands: K and M (2.2 and 5 m, respectively). The reconstruction in K of a north-south scan clearly shows three components inside a circumstellar shell. On the other hand, in the M band only a wing on the north side of the main component is resolvable.This paper was published in Journal of the Optical Society of America A, and is made available as an electronic reprint with the permission of OSA. The paper can be found at the following URL on the OSA website: [article URL]. Systematic or multiple reproduction or distribution to multiple locations via electronic or other means is prohibited and is subject to penalties under law.Peer reviewe

Parallel optimization of tetrahedral meshes

[EN]We propose a new algorithm on distributed-memory parallel computers for our simultaneous untangling and smoothing of tetrahedral meshes [9, 10]. A previous parallel implementation on shared-memory computers is analyzed in [1]. The new parallel procedure takes ideas from Freitag et al. strategy [11]. The method is based on: partitioning a mesh, optimizing interior vertices, optimizing boundary vertices of interior partitions, and communicating updated coordinates of boundary vertices. This paper presents performance evaluation results of our parallel algorithm. We apply the procedure in the mesh generation of several 3-D objects by using the Meccano method [4]. High levels of speed-up are obtained in the mesh optimization step of this method. How ever, several bottlenecks may limit the parallelism. We provide some hypotheses about the factors that cause more parallel overhead. The relative number of elements, that are located at the interfaces of the sub-domains of the object, is one of the more important aspects for the e ciency of the parallel mesh optimization.Ministerio de Econom ía y Competitividad del Gobierno de Españ

PASOS PARA LA INTENSIFICACION DE LA CRIA EN CORRIENTES, ARGENTINA

El proceso de adopción tecnológica en sistemas de crí­a es lento. Uno de los motivos es la dificultad de transmitir las tecnologí­as de procesos, las cuales además requieren un perí­odo de aprendizaje. Una manera de facilitar su adopción, es informar acerca del impacto productivo que genera la incorporación de ellas. En primer lugar, se sintetizan las tecnologí­as consideradas por expertos como básicas y, en segundo término, las tecnologí­as mejoradoras del modelo productivo básico propuestas en forma secuencial por los autores. Por último, se evalúa el impacto productivo a medida que se va intensificando la actividad de crí­a. La priorización de tecnologí­as mejoradoras es (1) eliminación de las vacas refugo, (2) manejo de la lactancia, (3) primer servicio en otoño con 18 meses de edad y (4) mejora del recurso forrajero en un 20% de la superficie. Los resultados indican que si todos los productores aplicaran el modelo básico de producción, habrí­a un 40% más de terneros en Corrientes. A su vez, con la incorporación de las tecnologí­as mejoradoras, la producción adicional de terneros aumentarí­a en forma gradual, alcanzando en el nivel tecnológico (4) un 120% más de terneros en Corrientes. Por lo expuesto, se demuestra los beneficios de la adopción

Prediction system based on domotic weather sensors for the energy production of solar power plants

Abstract The prediction of the electrical energy generated by a photovoltaic system is useful for estimating the profitability analysis of a project, without the need of expensive photovoltaic prototypes. Prediction systems are usually based on simulating the physical process of a photovoltaic module, under standard or average local weather conditions. These predictions introduce some errors caused by the use of a theoretical model or average climate data. In our investigations, we noted that the energy generated by a photovoltaic system is proportional to the cumulative measurement of the sun illuminance that is provided by a low-cost domotic weather station. From this experimental observation, this paper proposes a hardware/software system for predicting the electrical energy generated by a photovoltaic system, such as those existing in buildings. The hardware consists of a domotic installation for monitoring both electric energy and climate parameters. The software consists of a calibration procedure, which provides a proportional factor between sun illuminance and the energy production per unit of surface area of the photovoltaic modules. Once the calibration procedure is completed, the photovoltaic energy production is predicted by factoring the sun illuminance provided by the weather station and the proportional factor provided by the calibration process. This method has been tested under real conditions and the accuracy reached up to 99.7% with an average value of 96.3%

A Model to Estimate the Laying Curve of White Leghorn Hens in the Last Three Years in the Province of Ciego de Avila, Cuba

A number of 15 976 egg production records from three hen batches in Ciego de Avila (2016) were used. The laying curve was characterized in similar conditions to IIA (2013), Republic of Cuba. The estimation of the laying curves made of mean productions from three stages in a year was presented. Four mathematical models were applied for curve adjustment: McNally, Wood, quadratic logarithmic, and linear hyperbolic. Different statistical criteria were used for validation: determination coefficient (R2), (R2A), residual analysis, and others. The means, standard deviation (SD), standard error (SE), and variation coefficient (VC) were made for each period. Egg production accounted for 84.35 and 60.61% of total laying, the best year was 2016. The highest values of SE and VC were observed at the end of production, as expected. Adjustment and discrimination showed a high adjustment criterion in the four models, but the best values were observed with McNally (1971), in R2 (99.60%), and adjusted R2 (99.42%). McNally reached the highest adjustment values: YM=-2233.62-18583.8*(MONTH/426)-029.0*(MONTH/426**2+780.241*log (426/MONTH)-68.1269*(log(426/MONTH))*2, and it described the best production of White Leghorn (L33) hens in Ciego de Avila

Modeling and analysis of dual three-phase self-excited induction generator

Multiphase self-excited induction generators have recently become more interesting due to its advantages compared to its equivalent three-phase generator. However, as an induction generator, it has some disadvantages regarding poor voltage and frequency regulation under varying load and speed regimes. A steady state analysis is fundamental to comprehend the machine’s behavior. This paper presents a detailed mathematical model and analysis of the dual three-phase self-excited induction generator. Simulation results are provided to show the behavior of the machine is build up voltage through different conditions, such as, variation of the excitation capacitance and variation of the mechanical rotor speed. For a more precise modeling, it is considered a non-linear variation of the magnetizing inductance.CONACYT – Consejo Nacional de Ciencia y TecnologíaPROCIENCI

The Meccano Method for Mesh Generation and Solid Parameterization

[EN]In this conference, we present the main advances in the meccano method, which was introduced by the authors in 2006 for tetrahedral mesh generation

Design and implementation of a modular bidirectional switch using SiC-MOSFET for power converter applications

Tis paper presents a novel modular design of a Bi-Sw with the purpose of providing to beginner researchers the key issues to design a power converter. Te Bi-Sw has been designed in modular form using the SiC-MOSFET device. Te Bi-Sw uses the advantages of SiC-MOSFET to operate at high switching frequencies. Te verifcation of the module is carried out experimentally by means of the implementation in a voltage regulating converter, where performance analysis, power losses, and temperature dissipation are performed.CONACYT – Consejo Nacional de Ciencia y TecnologíaPROCIENCI

Experimental assessment of IGBT and SiC-MOSFET based technologies for matrix converter using predictive current control

Matrix converters are devices that allow the management of bidirectional flows of energy, reduced size, increased useful life and high efficiency in wind schemes. In this paper we present the experimental results obtained after the application of a predictive current control technique for two matrix converters feeding isolated loads. One scheme is based on IGBT technology and the other on SiC-MOSFET technology. The results obtained reflect the correct functioning of the proposals, reaching a current control working up to 2 kW of power. Finally some comparisons in terms of power consumption and total harmonic distortion are presented.CONACYT – Consejo Nacional de Ciencia y TecnologíaPROCIENCI

La tasa de descuento en el proceso de valoración de empresas: un estudio empírico en Colombia

La valoración de empresas es una actividad cada vez más importante en un contexto globalizado, con empresas más dinámicas e internacionalizadas en busca de la creación de valor. La internacionalización afecta cada vez más a los países en desarrollo que se ven impelidos a tratar con operaciones de compra-venta internacionales y demandas de sus partners cada vez más especializadas, como es el caso de Colombia. Normalmente el método utilizado en la valoración es el descuento de los flujos de efectivo, lo que precisa el uso de tasas de actualización ad-hoc. Este trabajo tiene como objetivo principal analizar la aplicación de la tasa de descuento en la actividad de valoración de empresas en Colombia. Para ello se lleva a cabo un estudio exploratorio de carácter empírico, sobre una encuesta realizada a 32 expertos colombianos en valoración de empresas. Nuestras principales conclusiones revelan que los valoradores colombianos siguen pautas comunes a los valoradores internacionales, aunque se observa una gran dispersión a la hora de estimar la tasa de descuento. De esta forma el trabajo realizado puede ser de interés no solo para los profesionales de la valoración, sino también para los académicos y empresarios que estén inmersos en este proceso, ya que ofrece información sobre la realidad colombiana en un contexto internaciona