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- Collins, Steve; Ruina, Andy; Tedrake, Russ; Wisse, Martijn
- Science 2005 v.307 no.5712 pp. 1082-1085
- controllers; energy; gravity; humans; locomotion; models; robots
- ... Passive-dynamic walkers are simple mechanical devices, composed of solid parts connected by joints, that walk stably down a slope. They have no motors or controllers, yet can have remarkably humanlike motions. This suggests that these machines are useful models of human locomotion; however, they cannot walk on level ground. Here we present three robots based on passive-dynamics, with small active ...
- Smith, David M.; Lopez, Liliana I.; Lin, R. P.; Barrington-Leigh, Christopher P.
- Science 2005 v.307 no.5712 pp. 1085-1088
- Earth atmosphere; electrons; energy; gamma radiation; models; photons; satellites; spectroscopy
- ... Terrestrial gamma-ray flashes (TGFs) from Earth's upper atmosphere have been detected with the Reuven Ramaty High Energy Solar Spectroscopic Imager (RHESSI) satellite. The gamma-ray spectra typically extend up to 10 to 20 megaelectron volts (MeV); a simple bremsstrahlung model suggests that most of the electrons that produce the gamma rays have energies on the order of 20 to 40 MeV. RHESSI detects ...