An attempt is made to explain the observed torsional oscillations of an airscrew by means of the 'wake' theory. It is shown that the aerodynamic torsional damping becomes negative at certain blade angles and frequencies; the frequencies, or speeds, at which a single blade becomes unstable are shown to differ slightly from the critical frequencies of a multi-blade airscrew. At low incidences it ...

644. Rising Incidence of Syphilis Among Rural HIV+ Men Despite Systematic, Point of Care Prevention Counseling Poonam Mathur, MD; John Zurlo, MD; Patsi Albright, CRNP, PhD; Tonya Crook, MD; Cynthia Whitener, MD; Ping Du, MD, PhD; Medicine, Hershey Medical Center, Hershey, PA; Medicine/Infectious Diseases, Pennsylvania State University, Milton S. Hershey Medical Center, Hershey, PA; Medicine/Pub...

PURPOSE To compare the effects of different 23- and 25-gauge microincision vitrectomy trocar cannula entry systems on incision architecture. METHODS We tested one ridged microvitreoretinal (MVR), one non-ridged MVR, one pointed beveled, and one round-tipped beveled blade (n=10 per blade design per incision type). Each blade's straight and oblique incision architecture was assessed in a silico...

background: many types of single-use blades are manufactured with different designs and materials. there have been several reports of difficulties in obtaining a view of the glottis with single-use laryngoscopes. the purpose of this prospective study was to compare the quickness and the success rate of endotracheal intubations with two different laryngoscope blades: disposable laryngoscope blad...

Stability and control of rotors at high advance ratio are considered. Stability of teetering, articulated, and gimbaled hub types is considered with a simple flapping blade analysis. Rotor control in autorotation for teetering and articulated hub types is examined in more detail for a compound helicopter (rotor and fixed wing) using the comprehensive analysis CAMRAD II. Autorotation is found to...

The Axial compressor is an integrated part of a gas turbine. The central part of compressors is its blades. Blade aerodynamic has a significant effect on compressor performance. Because of the adverse pressure gradient in the compressor, any deviation in the blade profile has a significant influence on the flow field as well as the compressor performance. During the manufacturing and operation ...

crops and agricultural products are subject to natural loading during growth. different mechanical forces are also exerted on them during harvest. one product, sugar cane, experiences large shear forces are during harvest. an examination of the crop properties and machine parameters of sugar cane are necessary to develop appropriate cutting tools and the optimization and design of harvesting ma...

The longitudinal axis of the maize leaf is composed of, in proximal to distal order, sheath, ligule, auricle and blade. The semidominant Liguleless3-O (Lg3-O) mutation disrupts leaf development at the ligular region of the leaf midrib by transforming blade to sheath. In a previous study, we showed that leaf sectors of Lg3 mutant activity are cell nonautonomous in the transverse dimension and ca...

Peter B. Moyle, Patrick K. Crain, Keith Whitener, & Jeffrey F. Mount Department of Wildlife, Fish, and Conservation Biology, University of California, 1 Shields Avenue, Davis CA 95616, U.S.A. (email: [email protected]) The Nature Conservancy, Cosumnes River Preserve, 13501 Franklin Blvd., Galt CA 95632, U.S.A. Department of Geology, University of California, 1 Shields Avenue, Davis CA 95616 U...

We carried out direct numerical simulations of the flow past a two-dimensional S822 wind turbine blade section at a chord Reynolds number of Re=100,000 and an angle of attack of α = 5deg. Without blade rotation the separated boundary layer “rolls up” into spanwise vortices which then “break up” into smaller scale structures leading to transition to turbulence. Simulation results compare favorab...