نتایج جستجو برای: propulsion

تعداد نتایج: 8858  

2014
George Kopasakis Joseph W. Connolly Jonathan Seidel

A summary of the propulsion system modeling under NASA’s High Speed Project (HSP) AeroPropulsoServoElasticity (APSE) task is provided with a focus on the propulsion system for the lowboom supersonic configuration developed by Lockheed Martin and referred to as the N+2 configuration. This summary includes details on the effort to date to develop computational models for the various propulsion sy...

2015
Zhixiong Li Xinping Yan Li Qin Kai Cheng J. T. Xing

Original scientific paper Unexpected severe hull deformation caused by wave loads poses alignment problem to the propulsion shaft line in large scale ships, which would significantly influence the dynamical performance of the marine propulsion system. How to suppress negative disturbance imposed by the interaction between water-hull-propulsion and ensure the normal operation of the marine propu...

Journal: :Journal of rehabilitation research and development 1998
S D Shimada R N Robertson M L Bonninger R A Cooper

Rehabilitation scientists and biomedical engineers have been investigating wheelchair propulsion biomechanics in order to prevent musculoskeletal injuries. Several studies have investigated wheelchair propulsion biomechanics; however, few have examined wheelchair propulsion stroke patterns. The purpose of this study was to characterize wheelchair propulsion stroke patterns by investigating join...

Journal: :Computer Physics Communications 2004
Shannon Cheng Mark Santi Murat Celik Manuel Martinez-Sanchez Jaime Peraire

Hall thrusters and other types of electric propulsion have become a tempting alternative to traditional chemical propulsion systems due to the high specific impulses they provide at relatively high efficiencies. Unlike conventional chemical propulsion systems, electric propulsion devices do not rely on the internal energy stored within their propellant. Instead, an external power source is used...

2016
Ameen M. Bassam Alexander B. Phillips Stephen R. Turnock Philip A. Wilson

It is proposed to install a hybrid fuel cell electric propulsion system on a domestic ferry. The fuel cell hybrid system is compared with the existing diesel propulsion system for this ferry using a developed time-domain threedegree of freedom ship simulator implemented in the MATLAB/Simulink environment. Performance comparison of the two systems is made in terms of first cost, fuel cost, syste...

Journal: :Journal of rehabilitation medicine 2015
Manon A T Bloemen Janke F de Groot Frank J G Backx Rosalyne A Westerveld Tim Takken

OBJECTIVE To determine the best test performance and feasibility using a Graded Arm Cranking Test vs a Graded Wheelchair Propulsion Test in young people with spina bifida who use a wheelchair, and to determine the reliability of the best test. DESIGN Validity and reliability study. SUBJECTS Young people with spina bifida who use a wheelchair. METHODS Physiological responses were measured ...

Journal: :Journal of biomechanics 2008
Evan J Goldberg Steven A Kautz Richard R Neptune

Instrumented treadmills offer significant advantages for analysis of human locomotion, including recording consecutive steady-state gait cycles, precisely controlling walking speed, and avoiding force plate targeting. However, some studies of hemiparetic walking on a treadmill have suggested that the moving treadmill belt may fundamentally alter propulsion mechanics. Any differences in propulsi...

Journal: :Clinical biomechanics 2003
Lan-Yuen Guo Fong-Chin Su Hong-Wen Wu Kai-Nan An

OBJECTIVE To investigate the characteristics of mechanical energy and power flow of the upper limb during wheelchair propulsion. DESIGN Mechanical energy and power flow of segments were calculated. BACKGROUND Very few studies have taken into account the mechanical energy and power flow of the musculoskeletal system during wheelchair propulsion. Mechanical energy and power flow have proven t...

2012
ALEXANDER LESHANSKY Alexander Leshansky

Submitted for the DFD10 Meeting of The American Physical Society “Corkscrew” vs. “tank-treading” propulsion of spirochetes. ALEXANDER LESHANSKY, Department of Chemical Engineering, Technion-IIT, Haifa, Israel, ODED KENNETH, Physics Department, Technion-IIT, Haifa, Israel — We consider the potential mechanism of spirochete propulsion driven by twirling of the outer cell surface coupled to counte...

2011
Iain D. Boyd

Electric propulsion thrusters are replacing small chemical thrusters used for spacecraft control and orbital maneuvers. These thrusters use a variety of mechanisms to convert electrical power into thrust and in general provide superior specific impulse in comparison to chemical systems. Electric propulsion has been under development for the last fifty years, and almost all thrusters are designe...

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