Abstract: A damper for controlling fluid flow may include a main body, a stator that includes a plurality of stator blades, and a rotor moveably connected to the stator and including a plurality of rotor blades. The damper may also include a rotation mechanism mounted to the main body to move the rotor between an opened position and a closed position. The shape of each of the plurality of stator blades and rotor blades may combine to form a shape such that the velocity of the fluid is increased thereby reducing or eliminating back pressure when the rotor is in the opened position.

Abstract: A damper for controlling fluid flow includes a main body, a stator and a rotor. The stator may be carried by the main body and include at least one blade having a predetermined shape. The rotor may be moveably connected to the stator and carried by the main body. The rotor may include at least one blade having a predetermined shape and may be moveable between an opened position and a closed position. The predetermined shape of the at least one stator blade and the at least one rotor blade may form a converging-diverging nozzle, and the stator and the rotor may be carried by the main body so that fluid flows through the main body substantially perpendicular thereto. The opened position may be defined as the at least one stator blade being aligned with the at least one rotor blade, and the closed position may be defined as the at least one stator blade being offset from the at least one rotor blade.

Abstract: A damper for controlling fluid flow includes a main body, a stator and a rotor. The stator may be carried by the main body and include at least one blade having a predetermined shape. The rotor may be moveably connected to the stator and carried by the main body. The rotor may include at least one blade having a predetermined shape and may be moveable between an opened position and a closed position. The predetermined shape of the at least one stator blade and the at least one rotor blade may form a converging-diverging nozzle, and the stator and the rotor may be carried by the main body so that fluid flows through the main body substantially perpendicular thereto. The opened position may be defined as the at least one stator blade being aligned with the at least one rotor blade, and the closed position may be defined as the at least one stator blade being offset from the at least one rotor blade.

Abstract: A two-way communications system that provides ubiquitous wireless data communication services, such as throughout the continental United States, by using a network of only a few, widely distributed radio base station (RBS) sites and the existing paging network infrastructure. The paging network infrastructure is used as an outbound link to request data from the remote field units. The outbound page message indicates a time and frequency at which the RBSs can expect to receive data from the field units. A network hub or message operations center (MOC) coordinates the operation of the paging systems and RBSs from a central location. For example, the MOC determines an available HF frequency and time for a particular field unit to transmit, and then issues the request for data to the field unit using the existing paging network infrastructure. The field units make use of paging receivers, and an HF transmitter to report remote data such as a geoposition or other sensor data when requested to do so.

Abstract: A two-way communications system provides ubiquitous wireless data communication services, such as throughout the continental United States, by using a network of only a few, widely distributed radio base station (RBS) sites and the existing paging network infrastructure. A network hub or mission operation center (MOC) coordinates the operation of the paging systems and RBSs from a central location. The paging network infrastructure is used as an outbound link over which each of the field units is regularly provided with a outbound data message containing information on the available frequencies and time slots the field units can use to transmit inbound data messages to the RBSs. If any of the field units desires to transmit data to MOC, the field unit selects an available frequency from the outbound data message, and transmits its data at the selected available frequency and time.

Abstract: A two-way communications system that provides ubiquitous wireless data communication services, such as throughout the continental United States, by using a network of only a few, widely distributed radio base station (RBS) sites and the existing paging network infrastructure. The paging network infrastructure is used as an outbound link to request data from the remote field units. The outbound page message indicates a time and HF frequency at which the RBSs can expect to receive inbound data from the field units. A network hub or mission operation center (MOC) determines a radio frequency which is expected to be propagating and clear at the time that a particular field unit is to use the frequency as an inbound link. The MOC then issues the request for data to the field unit using an existing inexpensive wireless system such as the paging network infrastructure.