Results 61 to 70 of about 189,174 (279)

A flight dynamics investigation of compound helicopter configurations [PDF]

, 2013
Compounding has often been proposed as a method to increase the maximum speed of the helicopter. There are two common types of compounding known as wing and thrust compounding.
Ferguson, K., Thomson, D.
core  

A contribution to vision-based autonomous helicopter flight in urban environments [PDF]

, 2005
A navigation strategy that exploits the optic flow and inertial information to continuously avoid collisions with both lateral and frontal obstacles has been used to control a simulated helicopter flying autonomously in a textured urban environment ...
Anadan, Arkin, Barron, Barrows, Brooks, Camus, Camus, Cobos, Collett, Duchon, Duchon, Duchon, Duchon, Filliat, Fleet, Franceschini, Franceschini, Gibson, Gibson, Horn, Lee, Lee, Lee, Lucas, Meyer, Mura, Muratet, Netter, Neumann, Reiser, Srinivasan, Srinivasan, Srinivasan, Viollet   +33 more
core   +4 more sources

Efficacy evaluation of pneumatic solid set canopy delivery system to control powdery mildew (Erysiphe necator) in Washington vineyards

Pest Management Science, EarlyView.
The findings of this study indicate that powdery mildew control achieved with the pneumatic solid set canopy delivery system (PSD‐SSCDS) was comparable with that of a conventional airblast sprayer. These results highlight the PSD‐SSCDS as a promising alternative spray technology. Abstract BACKGROUND In this study, a previously optimized pneumatic spray
Dattatray G Bhalekar, Eric Mozzanini, Ramesh K Sahni, Michelle M Moyer, Lav R Khot   +4 more
wiley   +1 more source

Influence of Smart Spring Support Parameters on Vibration Characteristics of Three Support Shafting

Applied Sciences, 2020
Smart spring support is a kind of active damping device based on piezoelectric material. It can effectively suppress the vibration of a shaft system in an overly critical state by changing the stiffness and damping of the support.
Miao-miao Li, Liang-liang Ma, Chuan-guo Wu, Zhuo Li, Ru-peng Zhu   +4 more
doaj   +1 more source

Assessing wildfire dynamics during a megafire in Portugal using the MesoNH/ForeFire coupled model

Quarterly Journal of the Royal Meteorological Society, EarlyView.
Weather conditions affect megafires by inducing different fire behaviors over several days or weeks. The coupled MesoNH/ForeFire code was used to represent the dynamics of fire generating pyro‐convective clouds. To advance the understanding of wildfire dynamics, high‐resolution coupled fire–atmosphere modeling was employed.
Cátia Campos, Flavio Tiago Couto, Filippe L. M. Santos, Paulo Pinto, Carolina Purificação, Hugo Miguel Silva, João Rio, Manuel Lopes, Roberta Baggio, Jean‐Baptiste Filippi, Maria José Monteiro, Daniele Bortoli, Rui Salgado   +12 more
wiley   +1 more source

Mapping River Bed Topography in Whitewater Rapids Using Bathymetric LiDAR

River Research and Applications, EarlyView.
ABSTRACT Bathymetric LiDAR captures river topography efficiently for clear and shallow water, but for mountain rivers, whitewater rapids still pose challenges. This study proposes a novel method to enable the extraction of bottom returns specifically in turbulent whitewater sections.
Jan Rhomberg‐Kauert, Theresa Himmelsbach, Florian Pöppl, Lucas Dammert, Martin Pfennigbauer, Gottfried Mandlburger   +5 more
wiley   +1 more source

Investigation of Moment and Damping Characteristics of Rotor Airfoil Dynamic Stall Under Unsteady‑Freestream

Nanjing Hangkong Hangtian Daxue Xuebao
Dynamic stall significantly limits the flight performance of helicopters. To reveal the mechanism behind the variations in aerodynamic moments and damping characteristics under unsteady freestream， a numerical simulation method for the unsteady flow ...
GAO Yuan, ZHAO Guoqing, JING Simeng, ZHAO Qijun, LU Fan   +4 more
doaj   +1 more source

Ground‐truthing of satellite imagery to assess seabird colony size: A test using Adélie penguins

Remote Sensing in Ecology and Conservation, EarlyView.
Adélie penguin colony size can be estimated from space using very high‐resolution (VHR; 0.3–0.6 m resolution) satellite imagery due to the contrast between their guano stain and the surrounding terrain. Our study assessed the utility of VHR imagery for making indirect assessments of changes in colony size.
Alexandra J. Strang, Dean P. Anderson, Esme Robinson, Grant Ballard, Annie E. Schmidt, David G. Ainley, Kerry Barton, Fiona Shanhun, Elissa Z. Cameron, Michelle A. LaRue   +9 more
wiley   +1 more source

Improving forest age estimation to understand subtropical forest regrowth dynamics using deep learning image segmentation of time‐series historical aerial photographs

Remote Sensing in Ecology and Conservation, EarlyView.
Accurately estimating forest age is key to understanding how forests recover and evaluating restoration success. We developed a two‐step deep learning approach using historical greyscale aerial photographs to map forest age at fine spatial scales. By combining a pre‐trained model with localized fine‐tuning, our U‐Net + ResNet50 architecture achieved ...
Ying Ki Law, Yi‐Fei Gu, Shuwen Liu, Guangqin Song, Aland H. Y. Chan, Cham Man Tse, Zhonghua Liu, Martha J. Ledger, Billy C. H. Hau, Sawaid Abbas, Jin Wu   +10 more
wiley   +1 more source

Dynamic Stall Mechanisms of Pitching Airfoil: IDDES Study Across Different Mach Numbers

Applied Sciences
This study investigates dynamic stall mechanisms of a pitching NACA 0012 airfoil through high-fidelity computational fluid dynamics (CFD) simulations.
Simeng Jing, Fan Lu, Li Ma, Qijun Zhao, Guoqing Zhao   +4 more
doaj   +1 more source