Supersonic through-flow fan engine and aircraft mission performance

A study was made to evaluate potential improvement to a commercial supersonic transport by powering it with supersonic through-flow fan turbofan engines. A Mach 3.2 mission was considered. The three supersonic fan engines considered were designed to operate at bypass ratios of 0.25, 0.5, and 0.75 at supersonic cruise. For comparison a turbine bypass turbojet was included in the study. The engines were evaluated on the basis of aircraft takeoff gross weight with a payload of 250 passengers for a fixed range of 5000 N.MI. The installed specific fuel consumption of the supersonic fan engines was 7 to 8 percent lower than that of the turbine bypass engine. The aircraft powered by the supersonic fan engines had takeoff gross weights 9 to 13 percent lower than aircraft powered by turbine bypass engines

The design and performance estimates for the propulsion module for the booster of a TSTO vehicle

A NASA study of the propulsion systems for possible low-risk replacements for the Space Shuttle is presented. Results of preliminary studies to define the USAF two-stage-to-orbit (TSTO) concept to deliver 10,000 pounds to low polar orbit are described. The booster engine module consists of an over/under turbine bypass engines/ramjet engine design for acceleration from takeoff to the staging point of Mach 6.5 and approximately 100,000 feet altitude. Propulsion system performance and weight are presented with preliminary mission study results of vehicle size

Numerical comparison of convective heat transfer augmentation devices used in cooling channels of hypersonic vehicles

Hypersonic vehicles are exposed to extreme thermal conditions compared to subsonic aircraft; therefore, some level of thermal management is required to protect the materials used. Normally, hypersonic vehicles experience the highest temperatures in the nozzle throat, and aircraft and propulsion system leading edges. Convective heat transfer augmentation techniques can be used in the thermal management system to increase heat transfer of the cooling channels in those areas. The techniques studied in this report are pin-fin, offset-fin, ribbed and straight roughened channel. A smooth straight channel is used as the baseline for comparing the techniques. SINDA '85, a lumped parameter finite difference thermal analyzer, is used to model the channels. Subroutines are added to model the fluid flow assuming steady one dimensional compressible flow with heat addition and friction. Correlations for convective heat transfer and friction are used in conjunction with the fluid flow analysis mentioned. As expected, the pin-fin arrangement has the highest heat transfer coefficient and the largest pressure drop. All the other devices fall in between the pin-fin and smooth straight channel. The selection of the best heat augmentation method depends on the design requirements. A good approach may be a channel using a combination of the techniques. For instance, several rows of pin-fins may be located at the region of highest heat flux, surrounded by some of the other techniques. Thus, the heat transfer coefficient is maximized at the region of highest heat flux while the pressure drop is not excessive

De arquitectura y arqueología

De arquitectura y arqueologí

4,4'-Dimethyl-2,2'-{[2,3,3a,4,5,6,7,7a-octa-hydro-1H-benzimidazole-1,3-di-yl]bis-(methyl-ene)}diphenol

The asymmetric unit of the title compound, C23H30N2O2, contains one half-mol-ecule, with a twofold axis splitting the mol-ecule in two identical halves. The structure of the racemic mixture has been reported previously [Rivera et al. (2009>) J. Chem. Crystallogr. 39, 827-830] but the enanti-omer reported here crystallized in the ortho-rhom-bic space group P21212 (Z = 2), whereas the racemate occurs in the triclinic space group P-1 (Z = 2). The observed mol-ecular conformation is stabilized by two intra-molecular O-H⋯N hydrogen bonds, which generate rings with graph-set motif S(6). In the crystal, mol-ecules are linked via non-classical C-H⋯O inter-actions, which stack the mol-ecules along the b axis

Genome Sequence of the Photoarsenotrophic Bacterium Ectothiorhodospira sp. Strain BSL-9, Isolated from a Hypersaline Alkaline Arsenic-Rich Extreme Environment.

The full genome sequence of Ectothiorhodospira sp. strain BSL-9 is reported here. This purple sulfur bacterium encodes an arxA-type arsenite oxidase within the arxB2AB1CD gene island and is capable of carrying out "photoarsenotrophy" anoxygenic photosynthetic arsenite oxidation. Its genome is composed of 3.5 Mb and has approximately 63% G+C content

Relación entre la seroconversión positiva de vacas holstein a neospora caninum y el aborto, muerte fetal temprana, momificación fetal, gestación a termino y mortalidad neonatal

El presente trabajo de investigación “Relación entre la seroconversión positiva de vacas holstein a Neospora caninum y el aborto, gestación a término, muerte fetal temprana, momificación fetal y mortalidad neonatal” tuvo como objetivo determinar si existe relación entre la presencia de neosporosis bovina y las variables en estudio. Para lo cual se propuso un estudio de cohorte transversal usando una sola encuesta serológica de ELISA para determinar el estatus de las vacas. Los datos sobre la presentación de los eventos o variables se tomaron de los registros ganaderos de hatos pertenecientes a la sierra sur del Ecuador provincias de Azuay y Cañar (Hacienda la Esmeralda, Criadero Guangarcucho, Hacienda Papaloma y Hacienda Turupamba) de donde de se estudiaron 100 animales seropositivos y 100 seronegativos durante un período entre el parto y el siguiente evento reproductivo. (parto-parto; parto-aborto; etc).Como pruebas de significación estadística se utilizó el Chi-cuadrado de Pearson, de Maentel y Haenzel y el Odds Ratio como análisis de riesgo. Obteniéndose los siguientes resultados: La relación entre el aborto y la seroconversión a Neospora caninum fue altamente significativa (P= 0,005), las vacas positivas tienen 2,73 veces más riesgo de abortar que las vacas negativas. Se determinó asociación entre la muerte neonatal y la seroconversión positiva (P= 0,046) por tanto los terneros de las vacas positivas tienen 2,53 veces más riesgo de morir antes de alcanzar el destete (2 meses) que los terneros de vacas negativas. Con respecto a las otras variables en estudio no se determinó asociación estadística.The present research “Relationship between the holstein cows positive seroconversion a Neospora caninum and the abortion, gestation at end ,early fetal death, fetal mummification, and neonatal mortality” had as objective to determine if there is relationship between the presence of neosporosis bovine and the variables of the study. In order to arrive to the above indicated objective, it was proposed a study of transversal cohort using a single ELISA serological survey to determine the status of the cows. Data regarded to the presentation of events or variables were taken from records of cattle herds belonging to the Southern Highlands of Ecuador, Azuay and Cañar provinces, from which a total of 100 seropositive and 100 seronegative animals were studied over a period between birth and the next reproductive event (calvin-calvin, calvin-abortion; etc.). Chi-square test of Pearson, Maentel and Haenzel were used as statistical significance tests, and Odds Ratio as risk analysis. The research arrived to the following results: The relationship between abortion and seroconversion to Neospora caninum was highly significant (P= UNIVERSIDAD DE CUENCA Dr. Jaime Eduardo Maldonado. Página 4 0.005), being the positive cows 2.73 times more likely to abort than the negative ones. It was determined association between neonatal death and positive seroconversion (P= 0.046), so the positive cow calves have 2.53 times more risk of dying before weaning than calves from negative cows. Regarding to the other variables in study, no statistical association was determined.Magíster en Reproducción AnimalCuenc