Results 21 to 30 of about 7,855,257 (229)

MATHEMATICAL MODELS OF THE RADAR SIGNAL REFLECTED FROM A HELICOPTER MAIN ROTOR IN APPLICATION TO INVERSE SYNTHESIS OF ANTENNA APERTURE

open access: yesИзвестия высших учебных заведений России: Радиоэлектроника, 2019
Introduction. The basis for solving the problem of aircraft recognition is the formation of radar portraits, reflecting the constructive features of aerial vehicles.
Sergey R. Heister, Thai T. Nguyn
doaj   +1 more source

Aerodynamic Characteristics of Helicopter with Ducted Fan Tail Rotor in Hover under Low-Speed Crosswind

open access: yesInternational Journal of Aerospace Engineering, 2020
The tail rotor of a helicopter operating under low-speed crosswind undergoes highly complex flow due to the interaction between the main rotor, fuselage, and tail rotor system.
Nahyeon Roh, Sejong Oh, Donghun Park
doaj   +1 more source

Helicopter Safe Landing Trajectory after Main Rotor Actuator Failures

open access: yesApplied Sciences, 2020
Main rotor actuator failure leads to catastrophic accidents for single main rotor helicopters. This paper focuses on safe landing trajectories after an actuator is locked in place by the remaining actuators, without introducing other control inputs.
Yunjie Wang   +3 more
doaj   +1 more source

Thrust pulsation of coaxial main rotor, caused by the blades relative position

open access: yesНаучный вестник МГТУ ГА, 2020
The influence of reciprocal position of the upper rotor blades in respect to the lower rotor blades is characteristic for coaxial main rotor. It is established that the initial azimuth of the blade, for example, of the upper rotor’s which does not ...
B. S. Kritsky   +3 more
doaj   +1 more source

Protocol for quantifying miRNA trafficking across the endosomal membrane

open access: yesFEBS Open Bio, EarlyView.
An in vitro protocol measures miRNA uptake into endosomes isolated from mammalian cell extracts, which are free of subcellular contaminants. Performed at 37 °C in the presence of ATP, it ensures the import of single‐stranded miRNA into the endosomal lumen.
Syamantak Ghosh   +2 more
wiley   +1 more source

Helicopter tail rotor orthogonal blade vortex interaction [PDF]

open access: yes, 2004
The aerodynamic operating environment of the helicopter is particularly complex and, to some extent, dominated by the vortices trailed from the main and tail rotors. These vortices not only determine the form of the induced flow field but also interact
Marshall, J.S.   +7 more
core   +1 more source

Design of Composite Gyrocopter Main Rotor Blade Involving Rib and Spar Elements [PDF]

open access: yesJournal of Engineering, Project, and Production Management, 2019
Gyrocopter or gyroplane is a type of rotorcraft that uses an unpowered main rotor in free autorotation to develop lift. Gyrocopter rotor blades have smaller cord length and longer span compared to helicopters blades.
Yonas Mitik Degu, Derbew Alebel
doaj   +1 more source

Current Status and Challenges in Data Collection for Aerospace Coatings Deposited by Plasma Spraying

open access: yesAdvanced Engineering Materials, EarlyView.
An innovative approach has been integrated into the GRENAT project to optimize plasma spraying and coating performance. Raw materials are accelerated and melted in the plasma generated by torches, creating coatings. Monitoring sensors collect process data which are combined with ex situ characterization data.
Lila Randriamananjara   +8 more
wiley   +1 more source

Optimization of the Production of Rubber Compounds Using Mathematical Models

open access: yesAdvanced Engineering Materials, EarlyView.
Rubber compounds were mixed in a batch internal mixer, and symbolic regression was used to derive mathematical models linking recipe and process parameters to ram path, torque, and mixing quality (incorporation, dispersion, distribution). Subsequent optimization with evolutionary algorithms identified operating conditions that reduce specific energy ...
Anke Bardehle   +7 more
wiley   +1 more source

Influence of Rotor Dynamic Scattering on Helicopter Radar Cross-Section

open access: yesSensors, 2020
With the continuous improvement and development of armed helicopters, the research on their stealth characteristics has become more and more in depth. In order to obtain the complex effect of stealth characteristics caused by the high-speed rotation of ...
Zeyang Zhou, Jun Huang
doaj   +1 more source

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