BACKGROUND A common knee injury mechanism sustained during basketball is landing badly from a jump. Landing is a complex task and requires good coordination, dynamic muscle control and flexibility. For adolescents whose coordination and motor control has not fully matured, landing badly from a jump can present a significant risk for injury. There is currently limited biomechanical information r...

EIREN K. JACOBSON, Scripps Institution of Oceanography, University of California, San Diego, 9500 Gilman Drive, La Jolla, California 92093-0208, U.S.A.; KARIN A. FORNEY, Marine Mammal and Turtle Divison, Southwest Fisheries Science Center, National Marine Fisheries Service, National Oceanic and Atmospheric Administration, 110 Shaffer Road, Santa Cruz, California 95060, U.S.A.; JAMES T. HARVEY, ...

Introduction: Spacecraft accumulate large position and velocity errors during the atmospheric entry phase of a planetary mission due to atmospheric uncertainties and limited control authority. The powered descent phase, which is the last phase of Entry, Descent, and Landing (EDL), is when the lander makes a controlled maneuver to correct for these errors. This maneuver must be computed onboard ...

This paper outlines a simple algorithm for automated landing of miniature aerial vehicles (MAVs). Utilizing estimates of height above ground from barometric pressure and optic flow measurements, repeated landings were performed with a 1.5 m wingspan MAV. With height above ground estimated from barometric pressure measurements alone, landing errors averaged 7.6 m. When optic flow and barometric ...

Unmanned planetary landers to date have landed "blind"; that is, without the benefit of onboard landing hazard detection and avoidance systems. This constrains landing site selection to very benign terrain, which in turn constrains the scientific agenda of missions. The state of the art Entry, Descent, and Landing (EDL) technology can land a spacecraft on Mars somewhere within a very large land...

We discuss a toy model to study the dynamics of individual particles in avalanches. The model describes a particle launched from an inclined infinite staircase. The particle is not allowed to bounce when it collides with the staircase. During the collision, the particle loses some energy, and after that slides on to the end of the step it landed on. The process then repeats itself. The dynamics...

In this report, we show that an arbitrarily given quadrilateral can always be interpreted as an image of a parallelogram and that the interpretation is unique aside from a multiplicative constant. Several applications of this theorem are discussed. It could be used to prove an old, geometrical theorem; it could facilitate the matching process when a sequence of images are available; it could be...