10,755 research outputs found
Comparisons of wing pressure distribution from flight tests of flush and external orifices for Mach numbers from 0.50 to 0.97
Wing pressure distributions obtained in flight with flush orifice and external tubing orifice installations for Mach numbers from 0.50 to 0.97 are compared. The procedure used to install the external tubing orifice is discussed. The results indicate that external tubing orifice installations can give useful results
Effect of an alternate winglet on the pressure and spanwise load distributions of a first generation jet transport wing
Pressure and spanwise load distributions on a first-generation jet transport semispan model at subsonic speeds are presented. The wind tunnel data were measured for the wing with and without an alternate winglet. The results show that the winglet affected outboard wing pressure distributions and increased the spanwise loads near the tip
Effect of winglets on a first-generation jet transport wing. 1: Longitudinal aerodynamic characteristics of a semispan model at subsonic speeds
The effects of winglets and a simple wing-tip extension on the aerodynamic forces and moments and the flow-field cross flow velocity vectors behind the wing tip of a first generation jet transport wing were investigated in the Langley 8-foot transonic pressure tunnel using a semi-span model. The test was conducted at Mach numbers of 0.30, 0.70, 0.75, 0.78, and 0.80. At a Mach number of 0.30, the configurations were tested with combinations of leading- and trailing-edge flaps
Effect of Winglets on a First-Generation Jet Transport Wing. 2: Pressure and Spanwise Load Distributions for a Semispan Model at High Subsonic Speeds
Pressure and spanwise load distributions on a first-generation jet transport semispan model at high subsonic speeds are presented for the basic wing and for configurations with an upper winglet only, upper and lower winglets, and a simple wing-tip extension. Selected data are discussed to show the general trends and effects of the various configurations
Paleodiversity of the Superfamily Ursoidea (Carnivora, Mammalia) in the Spanish Neogene, related to environmental changes
In the present study we analyse the diversity of the Superfamily Ursoidea during the Neogene of the Iberian Peninsula to further compare it with that of the Neogene of Western Europe to find the different associations of this group. The results indicate that both the diversity and the taxonomy amongst these two regions show important variations, thus letting their interpretation in terms of climatic differentiation. We might relate variations in the abundance of the Ursoidea to the environmental fluctuations taking place during the Miocene and Pliocene. Therefore, they could enable us to reach the assessment of these biogeographical distributions in order to deduce the preferential niches of each different group of Ursoidea.En este trabajo se analiza la diversidad de la Superfamilia Ursoidea durante el Neógeno de la PenÃnsula Ibérica, comparándola con la de Europa Occidental de la misma época, con el objetivo de localizar las diferentes asociaciones de los miembros de este grupo. Los resultados indican que tanto la diversidad como la taxonomÃa varÃan considerablemente entre las dos regiones estudiadas pudiendo interpretarse en térÂminos de diferenciación climática. Estas variaciones en la abundancia de Ursoidea se pueden relacionar con las fluctuaciones ambientales que tuvieron lugar durante el Mioceno y el Plioceno. Por tanto, nos ayudarán a evaluar las causas de estas distribuciones biogeográficas y a encontrar los nichos preferentes de cada uno de los diferentes grupos de Ursoidea
Musteloidea (Carnivora, Mammalia) del Mioceno Superior de Venta del Moro (Valencia, España)
The purpose of the present work is to describe the Musteloidea from the Late Miocene locality of Venta del Moro (Valencia, Spain). We have identified the following species: Martes ginsburgi nov. sp., Lutra affinis Gervais, 1859, Plesiogulo monspessulanus Viret, 1939 and Promephitis alexejewi Schlosser, 1924. Besides Plesiogulo monspessulanus which was already described in this locality and in Las Casiones (MN 13, Teruel Basin), we are approaching an unedited Musteloidea assemblage from the Miocene of the Iberian Peninsula. The m1 of Martes ginsburgi nov. sp. is similar in size and morphology to the Asian species of the genus, M. anderssoni and M. zdanskyi, but it differs in having a very wide M1 with a developed lingual platform. The presence of Lutra affinis is the third register of this species in the fossil record, since it was only previously known from the Pliocene of Montpellier (France) and the terminal Miocene of Maramena (Greece). Promephitis alexejewi is the first appearance of this species in Europe, which has been only registered until now in several localities of Mongolia and China. It differs from the rest of Promephitis species in the possession of a narrower m1, with a very sectorial trigonid.Se describen los Musteloidea procedentes del Mioceno terminal (MN13) de Venta del Moro (Valencia, España). Se han determinado los siguientes taxones: Martes ginsburgi nov. sp., Lutra affinis Gervais, 1859, Plesiogulo monspessulanus Viret, 1939 y Promephitis alexejewi Schlosser, 1924. Exceptuando a P. monspessulanus, que ya se ha citado también en la MN13 de Las Casiones (Teruel), se trata de una asociación inédita en el Mioceno de la PenÃnsula Ibérica. Martes ginsburgi nov. sp. se asemeja en talla y morfologÃa del m1 a las especies asiáticas del mismo género M. anderssoni y M. zdanskyi, pero se diferencia de ellas por la posesión del un M1 muy ancho, con una plataforma lingual muy desarrollada. La presencia de Lutra affinis supone la tercera cita de esta especie en el registro fósil, ya que sólo se conocÃa en el Plioceno de Montpellier (Francia) y en el Mioceno terminal de Maramena (Grecia). Promephitis alexejewi supone la primera cita para Europa de esta especie registrada hasta ahora sólo en dos yacimientos de Mongolia y China. Se diferencia del resto de especies afines por la posesión de un m1 más estrecho, con trigónido muy sectorial
Modelamiento Matemático para malaria bajo resistencia y movimiento poblacional
En este artÃculo se presentan dos modelos matemáticos para la enfermedad de la malaria bajo la hipótesis de resistencia. Más precisamente, el primer modelo muestra la interacción entre humanos y mosquitos de una región con presencia de infección, considerando que los humanos son resistentes a la droga antimalárica y los mosquitos resistentes a los insecticidas. En el segundo modelo, se consideran las mismas hipótesis del modelo anterior, y adicionalmente movimiento de ambas poblaciones entre regiones. Para el primer modelo, se establecen condiciones de existencia y estabilidad para las soluciones de equilibrio en términos del número básico de reproducción. Estos resultados revelan la existencia de una bifurcación hacia adelante y la estabilidad global del equilibrio libre de enfermedad (DFE por sus siglas en inglés). Para el segundo modelo, se presenta un enfoque teórico y numérico de análisis de sensibilidad de parámetros. Además, se incorporan el uso de droga antimalárica e insecticidas como estrategias de control, con lo cual se formula un problema de control óptimo. A lo largo de este trabajo, los resultados teóricos se validan mediante simulaciones numéricas usando datos reportados en la literaturaIn this work, two mathematical models for malaria under resistance are presented. More precisely, the first model shows the interaction between humans and mosquitoes inside a patch under infection of malaria when the human population is resistant to antimalarial drug and mosquitoes population is resistant to insecticides. For the second model, human–mosquitoes population movements in two patches is analyzed under the same malaria transmission dynamic established in a patch. For a single patch, existence and stability conditions for the equilibrium solutions in terms of the local basic reproductive number are developed. These results reveal the existence of a forward bifurcation and the global stability of disease–free equilibrium. In the case of two patches, a theoretical and numerical framework on sensitivity analysis of parameters is presented. After that, the use of antimalarial drugs and insecticides are incorporated as control strategies and an optimal control problem is formulated. Numerical experiments are carried out in both models to show the feasibility of our theoretical results
Amazon River infl uence on nitrogen fi xation in the western tropical North Atlantic
We measured rates of N- and C-fixation with a direct tracer method in regions of the western tropical North Atlantic influenced by the Amazon River plume during the high flow period of 2010 (May–June 2010). We found distinct regional variations in N-fixation activity, with the lowest rates in the plume proper and the highest rates in the plume margins and in offshore waters. A comparison of our N- and C-fixation measurements showed that the relative contribution of N-fixation to total primary production increased from the plume core toward oceanic waters, and that most of the C-fixation in this system was supported by sources of nitrogen other than those derived from biological N-fixation, or diazotrophy. We complemented these rate experiments with measurements of the δ15N of suspended particles (δ15PN), which documented the important and often dominant role of diazotrophs in supplying nitrogen to particulate organic matter in the water column. These coupled measurements revealed that small phytoplankton contributed more new nitrogen to the particulate nitrogen pool than larger phytoplankton. We used a habitat classification method to assess the fac- tors that control diazotrophic activity and contribution to the suspended particle pool, both of which increased from the plume toward oceanic waters. Our findings provide an important constraint on the role of the Amazon plume in creating distinct niches and roles for diazotrophs in the nutrient and carbon budgets of the western tropical North Atlantic
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