FLUID FLOW SENSOR NASA Case No. XMF-04163 Canada Address inquiries to: [Corresponding to U.S. Patent No. 3,340,732] A meteorological balloon having superior response and aerodynamic stability characteristics due to provision of a plurality of evenly dispersed protuberances on the balloon surface. These protuberances form a roughened surface to provide a more evenly distributed flow separation area to induce a larger balloon wake, resulting in greater stability in flight. APPARATUS FOR CONTROLLABLY NASA Case No. XMF-04237 Canada Address inquiries to: Huntsville, AL 35812 [Corresponding to U.S. Patent No. 3,517,162] This invention is associated with fluid heating devices which operate by circulating fluid past an electronically controlled heater element in a flow conduit. The efficiency of such devices is increased by placing the heater control components in the conduit, upstream from the heater element, thereby utilizing the heat generated in the control components for preheating the fluid anterior to the principal heater element. Apparatus for synchronizing a satellite time division multiplex system so that signals can be transmitted or received between any of the stations. The system constantly compensates for Doppler shift so that a medium altitude satellite is always in synchronization. Additionally, a system is provided for centering a slave station in an empty slot in the time division multiplex format. INVERTER WITH MEANS FOR BASE CURRENT NASA Case No. XGS-06226 Canada Address inquiries to: Goddard Space Flight Centér Mail Code: 204 Greenbelt, MD 20771 [Corresponding to U.S. Patent No. 3,466,570] Inverters are utilized for converting a source of direct current to alternating current, or alternately for converting a source of direct current to a first voltage level alternating current and then to a second desired direct current voltage level. The concept employed in the inverters of this invention employs semiconductors and utilizes means for base current shaping for sweeping charge carriers from the base region. More specifically, the provision of both an inductance and a saturable reactor in the frequency determining network of a push-pull transformer coupled oscillator-inverter drastically improves performance. The circuit inhibits abnormal surges, spikes or ripples which are usually present at an energy source output. Short circuit protection is provided and increased reliability and efficiency is obtained by reducing the switching transistor overlap without requiring the application of a high inverse base to emitter voltage. A further feature is the provision of a means for controllably separating the base drive current reduction (switching-off transistor) and base drive current overdrive (switching-on transistor) into two distinct and separate time intervals. THERMAL CONTROL PANEL NASA Case No. XLA-07728 Canada Address inquiries to: [Corresponding to U.S. Patent No. 3,374,830] It is necessary to protect the interior of space vehicles from the extreme environmental temperature changes encountered in space missions. For this purpose a thermo-sensitive panel construction has been developed for achieving selectively changeable and controllable surface solar absorptivity/emissivity ratios. The result is obtained by altering the molecular structure of the panel construction through such changes as electroluminescence, semiconductivity, photovoltaic effect and electro-optical polarization. |