Abstract: An improved hypersonic aerodynamic configuration which has a nose portion and cavity formed at the bow of the nose portion. An optical window arrangement is provided at the base of the cavity such that during flight, temperatures at the optical window are reduced as a result of maintaining the cavity substantially within a subsonic region of the bowshock. The cavity can be gas pressurized in order to maintain a stable pressure and reduce the amplitude of shock oscillations in front of the cavity produced by movement of the bowshock. The cavity configuration also achieves a reduction in optical aberrations about the optical window by maintaining a line of sight near normal to the bowshock. The cavity also produces reduced heat and turbulence about the optical window compared to a window location equidistant from the nose to the side of the cone.

Abstract: A data communications network has a transmission data channel wherein a plurality of network nodes are connected thereto according to a loop topology. Each node has a transceiver, a control switch for operating the node in either a pass through state, wherein received data from an upstream side of the channel is transmitted to the downstream side of the channel, or in a source transmit state wherein the node transmits its own message data to the downstream side of the channel while monitoring the upstream side. In the source transmit state, the node matches the received data with its transmitted data and truncates its transmission upon recognition of an error in the received message. In this manner, there is no requirement that the destination node acknowledge receipt of the data since the data received by the transmitting node is the most corrupted form of the data. The node further has a bus contention protocol wherein the node "backs off" from transmitting on the channel for a specific time-out duration.

Abstract: A down hole shut-in device effects a stoppage of effluent from a blown-out oil well by freezing a plug of the effluent within the well. The down hole shut-in device is installed within a conventional tubing string or casing string and includes a tubular member having a structural outer wall and a relatively thin, heat-exchanging inner wall. During normal operations, a substantially non-compressible fluid is maintained within the volume bounded by the outer and inner walls for transmitting pressure exerted upon the thin inner wall to the structural outer wall. During a blow-out or other loss of well control, the substantially non-compressible fluid is replaced by a refrigerated fluid for removing heat from the effluent flowing within the tubular member. A series of flow deflectors are mounted to the inner wall and are normally flush therewith.