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El control por orientación de campo es una técnica empleada en los servos mecanismos en CA que posibilita alcanzar una respuesta rápida de torque debido a que se basa en la interacción entre flujo y corriente como en un motor CC. Una alternativa para el control de los servos mecanismos en CA es el Control Directo de Torque que representa un avance en el objetivo de mejorar el desempeño y confiabilidad en el control de motores de inducción y que se basa fundamentalmente en la comparación de los valores instantáneos, de Torque y Flujo, calculados a partir de sus variables primarias (voltaje y corriente de estator), con sus respectivos valores de referencia. Los errores de Flujo y Torque resultantes son procesados por controladores por histéresis para luego seleccionar el voltaje a ser aplicado, a través del accionamiento de las llaves de potencia de un Inversor trifásico de tens...

Field orientation control is a technique used in AC servo mechanisms that makes it possible to achieve a rapid torque response because it is based on the interaction between flux and current as in a DC motor. An alternative for servo controlmechanisms in AC is the Direct Torque Control that represents an advance in the objective of improving the performance and reliability in the control of induction motors and is fundamentally based on the comparison of the instantaneous values ​​of Torque and Flow, calculated from of its primary variables (stator voltage and current), with their respective reference values. The resulting Flow and Torque errors are processed by hysteresis controllers to then select the voltage to be applied, through the activation of the power switches of a three-phase voltage inverter. The selection criteria are made so that there is a rapid torque response and hig...

The effectiveness of a combined treatment of cloprostenol and cabergoline was evaluated for interruption of gestation in bitches. A clinical experience is reported in an English bulldog bitch with a gestation of 30 days. The treatment was administrated every 24 hours and consisted in 5 μg/kg of cabergoline, orally, followed 30 minutes later by 1 μg/kg of cloprostenol, via subcutaneous. Physiological constants, effects post administration, and ecographic evolution of the gestation was evaluated. Also, progesterone concentration was determined in two blood samples using a quantitative commercial kit. Changes in gestational vesicles were observed at day 3 of treatment, and a lower cardiac frequency (<180 bpm) were recorded on day 4. A fetal expulsion occurred few hours later. Ultrasound on day 5 showed absence of vesicles and fetuses. Serum progesterone concentration on day 3 was 1 to ...

Se evaluó la efectividad de un tratamiento combinado de cloprostenol y cabergolina como método de interrupción de la gestación en hembras caninas. Se describe el caso de una perra Bulldog Inglés con gestación estimada de 30 días. Cada 24 horas se aplicó 5 μ/kg de cabergolina, vía oral, seguido a los 30 min de 1μ/kg de cloprostenol, vía subcutánea. Se evaluaron constantes fisiológicas, efectos post administración y evolución ecográfica de la gestación; asimismo, se determinó la concentración de progesterona sérica utilizando un kit comercial cuantitativo. Cambios en las vesículas gestacionales se observaron en el día 3 del tratamiento, y en el día 4 se evidenció una frecuencia cardíaca disminuida (<180 lpm), y una expulsión fetal horas más tarde. El examen ecográfico del día 5 mostró ausencia de vesículas gestacionales y fetos. La progesterona sérica en...

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En el presente artículo se muestran los resultados de simulación obtenidos del estudio de un sistema electrónico de potencia, que mejora significativamente el desempeño del filtro pasivo trifásico convencional que normalmente se utiliza para la compensación del factor de potencia de cargas no lineales. Esta mejora se logra, conectando un filtro activo trifásico (FA) (o unidad activa) en serie con el filtro pasivo a (FP) través de tres transformadores de acoplamiento y controlando al filtro activo de manera que obligue a las componentes armónicas generadas por el rectificador a pasar por el filtro pasivo. A esta topología en la que se combina un filtro pasivo con un filtro activo se le conoce como Filtro Híbrido de Potencia.

This article shows the simulation results obtained from the study of a power electronic system, which significantly improves the performance of the conventional three-phase passive filter that is normally used for power factor compensation of non-linear loads. This improvement is achieved by connecting a three-phase active (AF) filter (or active unit) in series with the passive (PF) filter through three coupling transformers and controlling the active filter in such a way as to force the harmonic components generated by the rectifier to pass through the passive filter. This topology in which a passive filter is combined with an active filter is known as Hybrid Power Filter.

Currently, small- and medium-sized enterprises face order fulfillment issues, thus generating reduced service levels. In addition, these companies are usually not aware of the importance of continuous improvement tools or of training staff as a mitigation strategy for this situation. Within this framework, the authors performed a literature review to compile production models through which downtimes could be reduced. The production model designed therefrom comprises Lean Manufacturing and work study tools within a Change Management approach. This design focuses on model implementation by small companies without requiring large investment, cutting-edge technology, or qualified personnel. Finally, an application case study was conducted in a small textile manufacturing company located at the Gamarra Fashion Center in Lima, Peru. The results that were reported revealed that late order fulfi...

Se presenta un estudio comparativo entre la componente inorgánica de una muestra de tejido óseo humano respecto de apatitas sintetizadas mediante precipitación química, síntesis mecanoquímica y una muestra de hidroxiapatita comercial. Las muestras fueron estudiadas mediante difracción de rayos X, espectroscopia por absorción atómica y espectroscopia infrarroja con transformada de Fourier. Los resultados obtenidos muestran características estructurales similares entre todas las muestras, identificándose que la muestra obtenida por síntesis mecanoquímica es un tipo de hidroxiapatita el cual presenta sustituciones de carbonato en su estructura cristalina similar a la componente inorgánica del tejido óseo.

Preservation methods of spermatozoa using refrigeration have been developed for canine sperm; however, the rate of fertilization is still low, possibly due to cell damage for unknown reasons. The objective of this study was to evaluate the effect of refrigeration upon motility, mitochondrial activity, acrosomal membrane integrity, and acrosomal reaction in dog sperm incubated in three culture media (Ferp Talp, CCMm, Sp Talp) using new methodologies (Mito Tracker, Lyso Tracker, SBTI). The results indicated that exist a significant decrease (p<0.05) in motility, mitochondrial activity, and acrosomal membrane integrity in refrigerated sperm in comparison with fresh sperm. Also, the dynamic of acrosomal reaction was different in refrigerated sperm in comparison with fresh sperm. The Sp Talp and CCMm media showed the best results in holding the mitochondrial activity and acrosomal membrane...

Métodos de preservación de espermatozoides mediante la refrigeración o el congelamiento han sido desarrollados para espermatozoides caninos; sin embargo, la tasa de fecundación artificial es baja, posiblemente por daños celulares aún no determinados. El objetivo de este estudio fue evaluar el efecto de la refrigeración sobre la motilidad, actividad mitocondrial, integridad de membrana acrosomal y reacción acrosomal en espermatozoides caninos incubados en tres medios distintos (Ferp Talp, CCMm, Sp Talp), utilizando nuevas metodologías (Mito Tracker, Lyso Tracker, SBTI). Los resultados indicaron una disminución significativa (p<0.05) en la motilidad, viabilidad e integridad del acrosoma en espermatozoides refrigerados en comparación con los frescos; así como una dinámica de reacción diferente en espermatozoides refrigerados respecto a los frescos. Por otra parte, los medio...

Malaria in Peru, dominated by Plasmodium vivax, remains a public health problem. The 1990s saw newly epidemic malaria emerge, primarily in the Loreto Department in the Amazon region, including areas near to Iquitos, the capital city, but sporadic malaria transmission also occurred in the 1990s-2000s in both north-coastal Peru and the gold mining regions of southeastern Peru. Although a Global Fund-supported intervention (PAMAFRO, 2005-2010) was temporally associated with a decrease of malaria transmission, from 2012 to the present, both P. Vivax and Plasmodium falciparum malaria cases have rapidly increased. The Peruvian Ministry of Health continues to provide artemesininbased combination therapy for microscopy-confirmed cases of P. Falciparum and chloroquine-primaquine for P. Vivax. Malaria transmission continues in remote areas nonetheless, where the mobility of humans and parasites fa...