The effects of fluid elasticity on the swimming behavior of the nematode Caenorhabditis elegans are experimentally investigated by tracking the nematode's motion and measuring the corresponding velocity fields. We find that fluid elasticity hinders self-propulsion. Compared to Newtonian solutions, fluid elasticity leads to up to 35% slower propulsion. Furthermore, self-propulsion decreases as e...

As Electric Propulsion (EP) increases in recognition as a means of spacecraft primary propulsion and orbit maintenance, more complex spacecraft using EP will be produced. With the proven adage, test what we fly and fly what we test, the ground and on-orbit verification programs for those spacecraft utilizing EP for primary propulsion also increases in complexity. While EP systems have been test...

Current interest in advanced propulsion within NASA and research activities in advanced propulsion concepts at the Jet Propulsion Laboratory are reviewed. The concepts,which include high power plasma thrusters such as lithiun~-fueled Lorentz-Force-Accelerators,MEMS-scale propulsion systems, in-situ propellant utilization techniques, fusion propulsion systems and methods of using antimatter, off...

We review recent advances in rectification control of artificial microswimmers, also known as Janus particles, diffusing along narrow, periodically corrugated channels. The swimmer self-propulsion mechanism is modeled so as to incorporate a nonzero torque (propulsion chirality). We first summarize the effects of chirality on the autonomous current of microswimmers freely diffusing in channels o...

OBJECTIVE Repetitive loading of the upper limb joints during manual wheelchair (WC) propulsion (WCP) has been identified as a factor that contributes to shoulder pain, leading to loss of independence and decreased quality of life. The purpose of this study was to determine how individual manual WC users with paraplegia modify propulsion mechanics to accommodate expected increases in reaction fo...

Evolutionary constraints which limit the forces produced during bell contractions of medusae affect the overall medusan morphospace such that jet propulsion is limited to only small medusae. Cubomedusae, which often possess large prolate bells and are thought to swim via jet propulsion, appear to violate the theoretical constraints which determine the medusan morphospace. To examine propulsion ...

This paper presents an efficient coil design for a mm-sized micro-robot which generates a propulsion force and torque and receives electrical energy using a wireless power transfer system. To determine the most efficient coil structures and produce propulsion and torque on the micro-robot, both helical and spiral coil modeling was conducted, and analytical formulations of the propulsion force a...

Design of high-performance electric propulsion systems requires thorough dynamic analysis of both the electric power and propulsion systems. This paper presents a simple but effective method to model the relevant components in the electric and propulsion plants to facilitate the integration and analysis of the entire system for the purpose of predicting the overall system performance. The objec...

One of the airplane design concepts that potentially allows for significantly increased efficiency, but has not yet been investigated thoroughly, is the inverted joined wing configuration, where the upper wing is positioned in front of the lower one. We performed wind tunnel and flight testing of a demonstrator of this concept, first by applying electrical propulsion to simplify wind tunnel tes...

In this paper, we describe a manual wheelchair propulsion classification system which recognizes different patterns using a wrist mounted accelerometer. Four distinct propulsion patterns have been identified in a limited user study. This study is the first attempt at classifying wheelchair propulsion patterns using lowfidelity, body-worn sensors. Data was collected using all four propulsion pat...