Quotables
"Rail travel at high speeds is not possible because passengers, unable to breathe, would die of asphyxia."
Dionysius Lardner, Professor of Natural Philosophy and Astronomy at University College, London ; 1830
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| Number | Title | Issue Date |
| 6875976 | Aperture monitoring system and method System and method for detecting the presence of an object in an aperture in which for modulated electromagnetic waves are directed from an edge of a frame defining the aperture and electromagnetic waves reflected from an opposite edge of the frame are received at su... | 04/05/2005 |
| 4626750 | Solid state d.c. motor control The system includes a plurality of parallel-connected power field effect transistors arranged for connection in series with the traction motor with a common control circuit connected to the gate electrodes of the field effect transistors to control the on... | 12/02/1986 |
| 4385268 | Two-quadrant operation system for a slip-recovery drive SCR devices replace the usual diodes of the rectifier bridge section of a wound-rotor slip-recovery system motor drive, and by selection of the retardation angle of the SCR's between either zero or close to 180°, two-quadrant operation is made possible, ... | 05/24/1983 |
| 4289995 | Electric door operator with slip clutch and dynamic braking An automatic door closer providing for use as a light duty door opener and having a slip clutch for protecting the electric gear drive power unit from damage due to overspeeding on excess loads applied by overriding manual door operation. Zener diodes acr... | 09/15/1981 |
