نتایج جستجو برای: propulsion
تعداد نتایج: 8858 فیلتر نتایج به سال:
1 , A. Stroupe 2 , H. Aghazarian 3 , M. Garrett 4 , P. Younse 5 , and M. Powell 6 . 1 Jet Propulsion Laboratory, MS 198-219, 4800 Oak Grove Drive, Pasadena, CA 91109, [email protected]; 2 Jet Propulsion Laboratory, MS 198-219, 4800 Oak Grove Drive, Pasadena, CA 91109, [email protected]; 3 Jet Propulsion Laboratory, MS 198219, 4800 Oak Grove Drive, Pasadena, CA 91109, Hran...
Over the last 10 years the electrical propulsion fleet grew three times faster than the world fleet. This paper provides an overlook of the main drivers supporting this impressive growth and explores supporting drivers for future growth. The paper also explores two emerging technologies in electrical propulsion and distribution and how these influence ship design: DC distribution and energy sto...
Studies of manual wheelchair propulsion often assume bilateral symmetry to simplify data collection, processing, and analysis. However, the validity of this assumption is unclear. Most investigations of wheelchair propulsion symmetry have been limited by a relatively small sample size and a focus on a single propulsion condition (e.g., level propulsion at self-selected speed). The purpose of th...
Objective. To compare the energy expenditure of two types of manual wheelchair propulsion. Design. Experimental and comparative design using matched controls. Background. A new manual wheelchair propulsion technique is proposed to minimize the overload exerted on the upper limb during the classical propulsion. The energy cost and other parameters of this new propulsion technique were evaluated....
During wheelchair propulsion, in order to apply power to the pushrim effectively, shoulder and trunk stabilization is needed to control arm movements and the consequent transfer of power from the limbs through to the pushrim. Available trunk control may be one of the most important force-generating mechanisms during wheelchair propulsion, particularly when an individual is fatigued or propellin...
Photofission enables a unique capability for the domain of non-chemical space propulsion. An ultra-intense laser enables the capacity to induce nuclear fission through the development of bremsstrahlung photons. A fundamental architecture and performance analysis of a photofission pulsed space propulsion system through the operation of an ultra-intense laser is presented. A historical perspectiv...
هدف از ارایه این پایان نامه بررسی و محاسبات نوترونی و ترمو هیدرولیک برای نمونه ای از راکتور مورد استفاده در پیشرانش فضایی به روش تحلیلی و مقایسه و بهینه سازی این محاسبات با نتایج حاصل از شبیه سازی همین قلب توسط کد mcnp می باشد. برای این منظور ابتداء انواع مختلف سیستم های پیرانش هسته ای مورد استفاده در پرتابه های فضایی را مورد بررسی قرار داده و نحوه عملکرد و کارایی آن ها را با یکدیگر مقایسه می ک...
In this paper, an overview of the techniques applied to AC electric propulsion field has been done. Actual study cases of electric ship propulsion schemes are considered. An impartial comparison between three-level converters versus two-level converter from the viewpoint of electric ship propulsion requirements has been done. Diodeclamped three-level converters using direct torque control (DTC)...
[Purpose] This study sought to ascertain whether, in hemiplegic patients, the effect of a wheelchair cushion to suppress pelvic posterior tilt when initiating wheelchair propulsion would continue in subsequent propulsions. [Subjects] Eighteen hemiplegic patients who were able to propel a wheelchair in a seated position participated in this study. [Methods] An adjustable wheelchair was fitted wi...
in this research the simulation of an air independent proton exchange membrane fuel cell (pemfc) propulsion system was taken into consideration. the system consists of several parts including pem fuel cell stack, metal hydride and liquid oxygen (lox) tanks, and also pre-heaters of oxygen and hydrogen gases along with other heat exchangers, to ensure proper operation of system. the heat recovery...
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