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...

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...

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...

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...

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...

The pattern of propulsion was investigated for five male paraplegics in six seating positions. The positions consisted of a combination of three horizontal rear-wheel positions at two seating heights on a single-purpose-built racing wheelchair. To simulate wheelchair propulsion in the laboratory, the wheelchair was mounted on high rotational inertia rollers. For three trials at each seating pos...

OBJECTIVE To understand the relationship between step length asymmetry and hemiparetic walking performance. DESIGN Descriptive. SETTING Gait analysis laboratory. PARTICIPANTS Convenience sample of 49 subjects with chronic hemiparesis. INTERVENTIONS Not applicable. MAIN OUTCOME MEASURES Subjects walked at their self-selected walking speed over both an instrumented mat and forceplates t...

The objective of this thesis is to describe the process for, and the overall design that resulted from the MIT/Draper Project from August, 1996 to May, 1997, including the specific design of the onstation propulsion subsystem for the Wide Area Surveillance Projectile, WASP. A summary of the technological needs of this nation, as determined by the MIT/Draper Project team begins the thesis. Possi...

(les Enjeux de la propulsion et de l'energetique a l'aube du 2P me siecle) (les Enjeux de la propulsion et de l'energetique a l'aube du 2P me siecle)

Background/Objective: The high demand on the upper limbs during manual wheelchair (WC) use contributes to a high prevalence of shoulder pathology in people with spinal cord injury (SCI). Leveractivated (LEVER) WCs have been presented as a less demanding alternative mode of manual WC propulsion. The objective of this study was to evaluate the shoulder muscle electromyographic activity and propul...