Neural Network Modeling and Dynamic Analysis of Different Types of Engine Mounts for Internal Combustion Engines.

This paper presents the results of studies on reducing the amount of vibrations in different frequency ranges generated by a combustion engine through the use of different types of engine mounts. Three different types of engine supports are experimentally and numerically analyzed, namely an elastomeric engine mount, an elastomeric engine mount with a hydraulic component and standard decoupling, and an elastomeric engine mount with a hydraulic component and a modified decoupler-with this engineering design being a novelty in the literature. Experimental tests that considered different excitation frequencies were performed for the three types of engine mounts. Experimental data for stiffness and damping were used to obtain nonlinear mathematical models of the two systems with hydraulic components through the use of an Artificial Neural Network (ANN). For the results, all of the mathematical models presented coefficients of determination, R2, greater than 0.985 for both stiffness and damping, showing an excellent fit for the nonlinear experimental data. Numerical results using a quarter-car suspension model showed a large reduction in vibration amplitudes for the first vibration model when using the hydraulic systems, with values ranging between 48.58% and 66.47%, depending on the tests. The modified system presented smaller amplitudes and smoother behavior when compared to the standard hydraulic model.

Primera incursión en la obtención de curieles libre de patógenos específicos en Cuba / First foray into the production of specific pathogen-free guinea pigs in Cuba

Resultados confiables y económicos solo son obtenidos cuando los animales de experimentación son aislados de factores ambientales y biológicos, implantándose en el biomodelo una microbiota normal, lejos de la presencia de microorganismos patógenos. El objetivo de la investigación fue obtener curieles libre de patógenos específicos por cesárea aséptica, mantenidos en aisladores y alimentados con dietas estériles. Se realizaron 26 histerectomías. Los animales fueron alimentados con una fórmula modificada (L-477) en forma de papilla hasta los 21 días y permanentemente después la C-484 sólida y granulada, esterilizadas a 121oC/20 minutos o a 1,5Mrad. Además fueron suplementados con vitamina C y B1. El forraje o heno fue consumido a partir de la primera generación. La microbiota gastrointestinal se administró por vía oral en 0,5 ml de una dilución de 10-6/g de contenido de la porción final del íleon, ciego y principio del colon de curieles, a las 24 y 48 horas del nacimiento. Se utilizó para el monitoreo microbiológico caldo Tioglicolato, caldo Triptona Soya y caldo Saboraud incubados aeróbicamente a temperatura de 55, 37 y 25oC respectivamente. Se obtuvieron 51 neonatos. La mortalidad más alta se registró entre los primeros 10 días de edad (58,8%). Se lograron 12 animales (3 machos y 9 hembras), 6 de las hembras se reprodujeron aproximadamente a los 9 meses de edad, lográndose 11 crías por parto normal. La metodología aplicada permitió obtener curieles libres de Salmonella sp, Pasteurella sp, Streptococcus del tipo A y C, Bordetella bronchiseptica, Toxoplasma gondii, Virus Sendai y parásitos internos y externos.

Confidence and economics results are only obtained when the animals are isolated of the environmental and biological factors, that could interfere the course of from investigation and when is being established in them, a normal microflora balanced far from the presence of pathogen microorganisms. They were accomplished 26 histerectomies. The animals were fed with a modified formula of L-477 in the form of porridge until 21 days of age and permanently after with the C-484 solid and granulated, sterilized at 121oC/20 minutes or 1,5Mrad. The forage or hay was consumed by the first generation since the 6 months of age. The gastrointestinal flora was administered by oral route with 0,5 ml of a dilution of 10-6/g of the contents of the ileum final portion, cecum and first part of the colon of conventionalized Dunkin Hartley guinea pigs, at 24 and 48 hours born. It was used for microbiological bacteria monitoring Thioglycolate broth, Tryptic Soy broth and Sabouraud broth incubated aerobically at temperatures of 55, 37 and 25oC respectively. There were obtained 51 newborns. The highest mortality was registered during the first 10 days of age (58,8%). There were archieved 12 animals: 9 female and 3 males. 6 of the female were reproduced approximately at 9 months of age and were archieved 11 normal delivery sucklings. There were obtained guinea pigs free of the followings specific pathogens: Salmonella sp., Pasteurella sp., Streptococcus of the group A y C. Bordetella bronchiseptica, Toxoplasma gondii, Sendai Virus, beside internal and external parasites.