Distributed flight control system using fiber distributed datainterface (FDDI)

The design of fault-tolerant distributed control systems is discussed. The application described is a generic flight control system (FCS) for a fighter aircraft. The system is designed for high redundancy and expandability to meet various requirements. The communication network is based on the fiber distributed data interface (FDDI), which provides a high level of electromagnetic interference resistance and reliability. The choice of fiber optic media also provides an extremely high bandwidth and tremendous growth capability for future communications needs. This study is not specific to FDDI or flight control systems. The methods and configurations presented should be applicable to many real-time control implementations     

The finite element approximation of vector fields in curvilinear coordinates

We demonstrate that it is possible to express each component of the displacement vector for the interior point of the finite element (FE) through all components of nodal unknowns in curvilinear coordinates. The effectiveness of the valid technique of vector approximation for displacement fields has been verified on an example.     

Scientific Planning and Commanding of the Rosetta Payload

ESA’s Rosetta mission was launched in March 2004 and is on its way to comet 67P/Churyumov-Gerasimenko, where it is scheduled to arrive in summer 2014. It comprises a payload of 12 scientific instruments and a Lander. All instruments are provided by Principal Investigators, which are responsible for their operations. As for most ESA science missions, the ground segment of the mission consists of a Mission Operations Centre (MOC) and a Science Operations Centre (SOC). While the MOC is responsible for all spacecraft-related aspects and the final uplink of all command timelines to the spacecraft, the scientific operations of the instruments and the collection of the data and ingestion into the Planetary Science Archive are coordinated by the SOC. This paper focuses on the tasks of the SOC and in particular on the methodology and constraints to convert the scientific goals of the Rosetta mission to operational timelines.     

Optimal friction control on a circular cylinder taking into account the reverse effect of the boundary layer

We analyze the effect of injection both of uniformly distributed over the entire cylinder surface and of the optimal one on the velocity distribution at the outer border of the boundary layer and, as a result, on friction.     

Investigation of the differential rotation of the large-scale magnetic elements for the solar activity cycles 20 and 21

The differential rotation of the patterns of the large-scale solar magnetic field during solar activity cycles 20 and 21 is investigated. Compact magnetic elements with the polarity of the general solar magnetic field have larger speed of rotation than the elements with the opposite polarity. The surface of the Sun was divided by 10°-zones. In all of them the average rotation rate of the magnetic elements with negative polarity is little higher than that of the magnetic elements with positive polarity, except for 50°-zone of the south hemisphere and at the 10° latitude of the north hemisphere.

The rates of differential rotation for large-scale magnetic elements with negative and positive polarities have similar behavior for both cycles of the solar activity.

The rotation rate varies at polarity reversal of the circumpolar magnetic fields. For the cycle No 20 in 1969–1970 the threefold reversal took place in the northern hemisphere and variations of rotation rate can be noticed for magnetic elements both with positive and negative polarity for each 10°-zone in the same hemisphere.     

Problems of application of face gasodynamic seals in aircraft engines

Problems arising in introduction of gasodynamic seals in aircraft engines are considered. The operation of a face gasodynamic seal as part of a natural gas pump is analyzed and its efficiency in the presence of oil is shown.     

Voting fusion adaptation for landmine detection

This paper presents a voting fusion application for use with a remotely controlled multisensor vehicle platform for antitank landmine detection. Data from three landmine detection sensors mounted at the front of the vehicle enhance the probability of detection and, when combined via data fusion, limit the false alarm density to practical levels. The performance of the voting fusion scheme presented in this paper is contrasted with a heuristic data fusion approach developed by General Dynamics Canada.     

NASA''s small spacecraft technology initiative “Clark” spacecraft

The Small Satellite Technology Initiative (SSTI) is a National Aeronautics and Space Administration (NASA) program to demonstrate smaller, high technology satellites constructed rapidly and less expensively. Under SSTI, NASA funded the development of “Clark,” a high technology demonstration satellite to provide 3-m resolution panchromatic and 15-m resolution multispectral images, as well as collect atmospheric constituent and cosmic x-ray data. The 690-Ib. satellite, to be launched in early 1997, will be in a 476 km, circular, sun-synchronous polar orbit. This paper describes the program objectives, the technical characteristics of the sensors and satellite, image processing, archiving and distribution. Data archiving and distribution will be performed by NASA Stennis Space Center and by the EROS Data Center, Sioux Falls, South Dakota, USA.     

Receiver antenna scan rate requirements needed to implement pulsechasing in a bistatic radar receiver

Pulse chasing is a technique implemented by a bistatic or multistatic radar system that allows rapid and efficient search of a desired volume of space whereby the receiving antenna is made to follow or “chase” the transmitted pulse as it travels radially outward from the transmitter antenna. An expression for receiver antenna scan rate requirements is derived that corrects an error in the prior literature. The results give significantly reduced scan rates in the forward scatter region near the baseline showing that pulse chasing is more easily implemented using conventional analog beamformer phased array technology than was suggested by prior work