12,049 research outputs found
F100(3) parallel compressor computer code and user's manual
The Pratt & Whitney Aircraft multiple segment parallel compressor model has been modified to include the influence of variable compressor vane geometry on the sensitivity to circumferential flow distortion. Further, performance characteristics of the F100 (3) compression system have been incorporated into the model on a blade row basis. In this modified form, the distortion's circumferential location is referenced relative to the variable vane controlling sensors of the F100 (3) engine so that the proper solution can be obtained regardless of distortion orientation. This feature is particularly important for the analysis of inlet temperature distortion. Compatibility with fixed geometry compressor applications has been maintained in the model
Conceptual-level evaluation of a variable stiffness skin for a morphing wing leading edge
A morphing leading edge produces a continuous aerodynamic surface that has no gaps between the moving and fixed parts. The continuous seamless shape has the potential to reduce drag, compared to conventional devices, such as slats that produce a discrete aerofoil shape change. However, the morphing leading edge has to achieve the required target shape by deforming from the baseline shape under the aerodynamic loads. In this paper, a conceptual-level method is proposed to evaluate the morphing leading edge structure. The feasibility of the skin design is validated by checking the failure index of the composite when the morphing leading edge undergoes the shape change. The stiffness of the morphing leading edge skin is spatially varied using variable lamina angles, and comparisons to the skin with constant stiffness are made to highlight its potential to reduce the actuation forces. The structural analysis is performed using a two-level structural optimisation scheme. The first level optimisation is applied to find the optimised structural proper- ties of the leading edge skin and the associated actuation forces. The structural properties of the skin are given as a stiffness distribution, which is controlled by a B spline interpolation function. In the second level, the design solution of the skin is investigated. The skin is assumed to be made of variable stiffness composite. The stack sequence of the composite is optimised element-by-element to match the target stiffness. A failure criterion is employed to obtain the failure index when the leading edge is actuated from the baseline shape to the target shape. Test cases are given to demonstrate that the optimisation scheme is able to provide the stiffness distribution of the leading edge skin and the actuation forces can be reduced by using a spatially variable stiffness skin
Fusarium wilt of banana in Brazil: current state and research advances at Embrapa towards sustainable disease management.
Fusarium wilt (FW) impairs banana production in large areas of Brazil, affecting mainly the most profitable cultivars: \'Maçã\' (Silk, AAB) and ‘Prata’ (Pomme, AAB). Plant nutrition is frequently associated with disease severity, but little is known about the banana-FW pathosystem in Brazil. In this work we samples 18 farms in four different production systems in SP. In each farm areas with low (FOC-) and high (FOC+) incidence of FW were selected for plant analysis. Lamina of the third leaf were sampled and analyzed for nutrient content. The main differences between FOC- and FOC+ areas were related to N, K and Ca contents. The most outstanding effect of FW on plant nutrition was the reduction of K and Ca. This might be explained by the fact K and Ca are highly linked to water transport and FW causes severe damages in the vascular system. Interestingly, a relative increase of N content was also observed in some FOC+ plants. This may be due to a concentration effect as a result of growth reduction caused by FW. Our data suggest FW triggers a feedback mechanism towards destabilization in banana. The significant reduction of Ca and K detected on infected plants and the documented role of these nutrients on plant resistance, open opportunities to better understand soil-based management strategies of FW in banana
Studying the Effect of Adding Aleppo Pylon to the Properties of Insulating and Accumulation of Polyvinyl Chloride Films
This research presents a study of the effect of adding natural and modified Aleppo Pylon (Syrian clay) in different proportions to the properties of polymeric films prepared from poly vinyl chlorid (PVC) polymer and dried at three different drying degrees (60oC, 100oC, 150oC). The clay surface was changed from hydrophilic to hydrophobic by treating the surface with quaternary alkyl ammonium salts. Both types of Aleppo Pylone were added to the polymer by weight (0%, 2.5%, 5%, 7.5%, 10%), and the polymeric films were prepared by way of mixing well of PVC polymer and clay. The mixing technique used hexanol as a solvent. The clay was mixed with the polymer at 150 Co temperature using a magnetic stirrer. The effect of adding natural and modified Aleppo Pylon to the properties of water absorption ratio, moisture content, migration of components in moderate, acidic and alkaline aqueous solutions, thermal stability and air permeability of polymeric films prepared from PVC polymer and clay with different drying degrees was studied and compared with them, in order to reach an improved PVC that can be used in the field of packaging
On Negotiation as Concurrency Primitive
We introduce negotiations, a model of concurrency close to Petri nets, with
multiparty negotiation as primitive. We study the problems of soundness of
negotiations and of, given a negotiation with possibly many steps, computing a
summary, i.e., an equivalent one-step negotiation. We provide a complete set of
reduction rules for sound, acyclic, weakly deterministic negotiations and show
that, for deterministic negotiations, the rules compute the summary in
polynomial time
Coleção Biológica de trabalho de Fusarium oxysporum f. sp. Cubense: do Laboratório de Fitopatologia.
A cultura da bananeira (Musa spp.) é a base econômica de muitas nações. E a banana, por sua vez, é a fruta mais consumida no mundo, sendo para alguns, item de segurança alimentar. A bananicultura está entre as atividades agrícolas de maior expressão econômica e social no Brasil.bitstream/item/56745/1/folder-colecao-biologica-de-trabalho-de-fusarium-oxysporum-INTERNET-2.pd
USING COORDIN'ATlON MEASURES FOR MOVEMENT ANALYSIS
Traditionally, in biomechanics we have investigated the actions of single joints or segments without taking into account the interactions of these structures. A dynamical systems approach has been increasingly used in biomechanics to give a different perspective on the interaction of specific structures in human movement. That is, the study of coordination has become more prominent in the biomechanics literature based on the work of Bernstein (1967). Coordination is defined as overcoming excessive degrees of freedom thereby turning individual movement elements into a controllable system. In this paper, we will' describe a theoretical framework for analyzing coordination, present examples in the literature and discuss future developments for this type of analysis
Convenience of the optical coherence tomography use for the diagnosis of oral lichen planus: an ex-vivo evaluation.
OVERUSE INJURIES IN RUNNING: DO COMPLEX ANALYSES HELP OUR UNDERSTANDING?
The purpose of this paper is to discuss the change in focus in biomechanics from relatively simple analysis techniques to more complex techniques. Overuse injuries, linked to rearfoot motion, will be used as an example. In the early development of biomechanical techniques, the angle magnitudes were presented to suggest the mechanisms of overuse injuries. Later, coupling rearfoot motion with actions of the knee became commonplace. In these analyses, the timing and ratios of the angular movements were expressed. However, none of these measures provided a sufficient explanation for injury mechanisms. New techniques, derived from dynamical systems theory, have provided a more salient explanation of the overuse injury mechanism through assessing the role of variability in movement coordination
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