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Search Results: 1 - 10 of 42007 matches for " Miguel Pedro;Torres "
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Las desigualdades regionales del desarrollo sustentable en México, 2000-2005
Miguel, Andrés E.;Torres, Julio C.;Maldonado, Pedro;Robles, Juan Carlos;
Región y sociedad , 2011,
Abstract: this article intends to analyze the behavior of sustainable development in mexico's regions during the period between 2000-2005, considering that sustainable development articulates growth, social justice and ecological conservation. the analysis concludes that sustainable regional development in this country is deteriorating, with inequalities and increasing imbalances between economy, welfare and environment. in order to quantify this deterioration, the index of sustainable water development was used as an indicator.
Las desigualdades regionales del desarrollo sustentable en México, 2000-2005
Andrés E. Miguel,Julio C. Torres,Pedro Maldonado,Juan Carlos Robles
Región y sociedad , 2011,
Abstract: Analizar el comportamiento del desarrollo sustentable de las regiones de México del a o 2000 al 2005 es el propósito del presente artículo; pues se considera que éste entrelaza el crecimiento, la equidad social y la conservación ecológica. Conforme al análisis se concluye que el desarrollo regional sustentable del país se está deteriorando con desigualdades y desequilibrios crecientes entre su economía, bienestar y medio ambiente. Para cuantificar el deterioro se utilizó, como indicador, el índice de desarrollo sustentable del agua.
Numerical Simulation of an Argon Stirred Ladle with Top and Bottom Injection  [PDF]
Sofia Torres, Miguel A. Barron
Open Journal of Applied Sciences (OJAppS) , 2016, DOI: 10.4236/ojapps.2016.613075
Abstract: The stirring of a molten steel ladle with argon injection through a top submerged lance and a bottom nozzle is numerically studied here through Computational Fluid Dynamics (CFD) simulations. Three lance submergence depths and three injection velocities are considered in the CFD numerical experiments. The turbulent dissipation rate is employed to characterize the stirring phenomenon. The mixing times are determined from the gas flow rate, ladle geometry and bath depth using an empirical correlation.
Serología diagnóstica de leptospirosis porcina en México 1995-2000
Cisneros Puebla,Miguel ángel; Moles Cervantes,Luis Pedro; Gavaldón Rosas,Dolores; Rojas Serranía,Nora; Torres Barranca,Jorge Isaac;
Revista Cubana de Medicina Tropical , 2002,
Abstract: results obtained from sample testing of 1 970 swines from a number of mexican farms were analyzed. such samples had been received in the leptospira lab of universidad autonoma metropolitana de xochimilco from 1995 to 2000. sera with titers equal to or higher than 1:1000 were considered positive; 39,8% of the animals were seropositive (784) and the most frequent serovarieties were bratislava, 22,5%; icterohaemorrhagiae strain palo alto, 14,5%; portland vere strain sinaloa acr, 13,8%; icterohaemorrhagiae, 11,1%; grippotyphosa, 8,9%; hardjo strain h89,7,2%; tarassovi,7,1%; panama, 5,8%, pomona and hardjo, 5,1%; wolffi, 3%; shermani, 2,4%; pyrogenes, 1,2%; canicola, 0,8%; hebdomadis, 0,5%. the bratislava serovariety has been reported as the cause of reproductive failure in several countries and it holds the first place in serological studies. therefore, the present paper provides information for stating that this is one of the most significant serovarieties in mexico.
Estudio serológico de leptospirosis bovina en México
Moles Cervantes,Luis Pedro; Cisneros Puebla,Miguel ángel; Gavaldón Rosas,Dolores; Rojas Serranía,Nora; Torres Barranca,Jorge Isaac;
Revista Cubana de Medicina Tropical , 2002,
Abstract: the results of 4 043 bovine sera samples from various mexican regions, which were sent to a diagnosis lab, were analyzed. the method was the agglutination technique, taking the dilution rate 1:1000 or higher as positive. the analysis revealed 31,1% of seroprevalence and the most frequent serovarietes were hardjo (strain h 89 isolated in mexico), wolffi and tarassovi. there is coincidence with early data obtained in mexico on a 34% of prevalence found in a similar study performed in 1994, and with the scientific literature from other countries. . the former study also indicated that tarassovi and wolffi were the most common leptospira, so there is coincidence with the figures in the reviewed literature. it was concluded that there was no significant variation in the prevalence rate between the 1994 study and the present one; therefore, it is recommended that this study be promoted so as to increase the bovine vaccination and achieve a reduction in leptospirosis in mexico.
Inverter-Based Diesel Generator Emulator for the Study of Frequency Variations in a Laboratory-Scale Autonomous Power System  [PDF]
Miguel Torres, Luiz A. C. Lopes
Energy and Power Engineering (EPE) , 2013, DOI: 10.4236/epe.2013.53027
Abstract:

This paper presents the modeling, simulation and practical implementation of an inverter-based diesel generator emulator. The main purpose of this emulator is for the study of frequency variations in diesel-based autonomous power systems in a laboratory environment where the operation of a real diesel generator is not possible. The emulator basically consists in a voltage source inverter with a second order output filter which voltage references are given by the model of the diesel generator. The control of the emulator is based on the digital signal processor TMS320F2812, where the mathematical models of the diesel generator and the control of the inverter are computed in real-time. Parameters for the model were obtained from commercially available components. Experimental results for different values of speed droop showed that the emulator achieves a satisfactory performance in the transient and stationary response. For the stationary response, the measured frequency deviates from theoretical values with a mean absolute error of: 0.06 Hz for 0% droop, 0.037 Hz for 3% droop, and 0.087 Hz for 5% droop. For the transient response, the measured frequency nadir deviates from simulations in: 0.05 Hz for 0% droop, 0.02 Hz for 3% droop, and 0.1 Hz for 5% droop.

Virtual Synchronous Generator: A Control Strategy to Improve Dynamic Frequency Control in Autonomous Power Systems  [PDF]
Miguel Torres, Luiz A. C. Lopes
Energy and Power Engineering (EPE) , 2013, DOI: 10.4236/epe.2013.52A005
Abstract:

Ideally, diesel hybrid autonomous power systems would operate with high penetration of renewable energy sources such as wind and photovoltaic to minimize fuel consumption. However, since these are inherently intermittent and fluctuating, the grid-forming diesel engine generator sets are usually required to operate with larger amounts of spinning reserve, often at low loading conditions what tends to increases operating and maintenance costs. Frequency stability is of great concern in “small” systems, such as mini-grids, where any individual generator in-feed represents a substantial portion of the total demand. There, the initial rate of change of frequency is typically larger and a lower value of frequency can be reached in a shorter time than in conventional systems with all generation supplied by rotating machines, possibly resulting in under-frequency load shedding and tripping of renewable energy generators. The first part of this paper, discusses some general concepts regarding frequency stability in a diesel hybrid mini-grid and how energy storage systems can be used to enhance system performance. Then, a particular technique based on a virtual synchronous generator is presented and its effectiveness is demonstrated with simulation results.

A Virtual Synchronous Machine to Support Dynamic Frequency Control in a Mini-Grid That Operates in Frequency Droop Mode  [PDF]
Miguel Torres, Luiz A. C. Lopes
Energy and Power Engineering (EPE) , 2013, DOI: 10.4236/epe.2013.53025
Abstract:

This paper addresses the problem of dynamic frequency control in a diesel-based mini-grid. It is shown that a virtual synchronous machine (VSM) can support dynamic frequency control by adding virtual inertia and damping to the system. However, it is found that the typical formulation of damping power does not work properly when the grid forming gen-set operates in droop mode because of the unknown stabilization value of the grid frequency. As a solution to this problem, an estimator for the stabilization frequency that works in conjunction with the damping function of the VSM is proposed. Theoretical and experimental results provide evidence of a satisfactory performance of the proposed VSM with estimator for different values of the gen-set droop factor. The estimated stabilization frequency converges in approximately 2 s and the maximum frequency deviation during the transient is reduced in 34%, on average.

Indu??o de embriogênese somática em genótipos de batata-doce
Magalh?es, Janaina S;Santos, Maria do Desterro M dos;Cunha Filho, Francisco N da;Blumer, Lucimara;Guerra, Miguel Pedro;Torres, Ant?nio Carlos;
Horticultura Brasileira , 2006, DOI: 10.1590/S0102-05362006000100016
Abstract: the differentiation and development of somatic embryos were observed in 15 genotypes of sweet potato using shoot tip explants with one or two leaf primordia. somatic embryogenesis was induced using ms media and vitamins, 3% sucrose, 0,2% phytagel, supplemented with 2,4-d (0,0; 0,5; 1,0 and 2,0 mg/l). the cultures were maintained in the dark at 27oc. the addition of 2,4-d was necessary for embryogenic callus induction in the genotypes '92', '94', '184', '188', '319', '370', '374', '442', '449', '549', '594', '645', 'pi3138463', 'white star' and 'jewel'. clones '169', '202', '605', '633' and '643' did not respond to embryogenic callus induction. embryogenic callus showed a yellow and opaque color, compact and granular texture. nonembryogenic callus was translucent in color and friable. calluses were originated at the periphery of explants. in the established conditions better formation of embryogenic calluses was obtained with 2,0 mg/l of 2,4-d. the transfer of embryogenic callus to 2,4-d free medium allowed embryo development to heart, torpedo and cotiledonary stages.
La entropía como indicador de las desigualdades regionales en México
Andrés Enrique Miguel-Velasco,Pedro Maldonado-Cruz,Julio César Torres-Valdéz,Maritza Cruz-Atayde
Economía, sociedad y territorio , 2008,
Abstract: En el presente artículo se analizan las desigualdades regionales a través del concepto entropía regional, tomando como referencia el desarrollo de las regiones de México a través del índice de desarrollo humano durante el periodo 1950-2003. La hipótesis que propone es que han aumentado las desigualdades regionales producto del desarrollo y que, en fechas recientes, los desequilibrios regionales detectados a través de la evaluación de la sustentabilidad regional tienden a ser mayores. Se propone como metodología para la medición de las desigualdades el empleo de los conceptos de entropía absoluta y relativa de los indicadores del desarrollo, la equidad, la eficiencia y la sostenibilidad de las regiones del país.
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