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Controllability of time-invariant discrete-time bilinear systems is discussed. Bilinear systems are classified into two categories: homogeneous and inhomogeneous. Sufficient conditions which ensure the global controllability of discrete-time bilinear systems are obtained by localized analysis in control variables.
The National Airspace System (NAS) is growing in complexity of aircraft, missions, and operations. In response, many organizations have published papers and concepts of operations (ConOps) for new and enhanced safety systems. The National Academies’ vision for an In-time Aviation Safety Management System (IASMS) is integral to Federal Aviation Administration (FAA) modernization efforts. The National Aeronautics and Space Administration (NASA) System-Wide Safety (SWS) project is conducting safety research, exploring solutions, and defining the safety needs of future missions, such as Advanced Air Mobility (AAM) and autonomous aircraft operating in a more connected, flexible, and dynamic airspace. IASMS enables and provides a path for bringing FAA’s operational vision to fruition through increasingly automated safety systems that integrate services, functions, and capabilities (SFCs). These SFCs provide the necessary responsiveness to monitor, assess, and mitigate known hazards and emergent risks. This paper describes how safety in today’s air transportation system will need to evolve, identifies key points regarding in-time safety, and explores the criticality of IASMS in the future NAS.
The existence of two previously unrecognized contributions to transit-time damping in systems of more than one dimension is demonstrated and discussed. It is shown that these contributions cannot be treated by one-dimensional analyses unless it is assumed that the gradient of the field perpendicular to itself always vanishes. Such an assumption is unjustified in general and the new contributions can dominate damping by fast particles in more general situations. Analytic expressions obtained using a Born approximation are found to be in excellent agreement with numerical test-particle calculations of transit-time damping for a variety of field configurations. These configurations include those of a resonance layer and of a spherical wave packet, which approximates a collapsing wave packet in a strongly turbulent plasma. It is found that the fractional power absorption can be strongly enhanced in non-slablike field configurations.
Many planned and proposed NASA science activities will benefit from precise real time positioning with wide area differential GPS (WADGPS). Future NASA users include orbital remote sensing instruments (altimeters, SARs, imagers) and a variety of airborne and Earth based investigations. Real time positioning requirements and goals range from a few meters to a few centimeters. Direct benefits will include the enabling of missions that are not now possible (such as precision remote sensing from the space shuttle and space station) and dramatic reduction of analysis costs for a diversity of current investigations.
Description of the implementation of a data compression system for the real-time operational transmission (through microwave links) of ATS satellite pictures between the command and data acquisition station and a central location for computer processing. The system features the use of general-purpose minicomputers for encoding and decoding; this makes it possible to vary the employed data compression technique and to make simultaneous statistical calculations on the data. Data compression and expansion is accomplished in a manner that does not lower data quality.
Design considerations of central programmer, common address, and data return bus
Shielding effectiveness and electromagnetic interference tests on multiplexer cables
Circadian oscillations and photoperiodic time measurement in Pectinophora gossypiella
System indicates status of computers and controls operational modes. Two matrices are used - one relating to permissible system states, the other relating to requested system states. Concept is useful to designers of digital data transmission systems and time shared computer systems.
Power spectral analysis of magnetic fields using Time/Data 100 system
Spectrographs for measuring hydrogen H beta line spectral shape and determining electron density of transient plasma
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An iterative procedure for determining the constant gain matrix that will stabilize a linear constant multivariable system using output feedback is described. The use of this procedure avoids the transformation of variables which is required in other procedures. For the case in which the product of the output and input vector dimensions is greater than the number of states of the plant, general solution is given. In the case in which the states exceed the product of input and output vector dimensions, a least square solution which may not be stable in all cases is presented. The results are illustrated with examples.
The overall aim was to evaluate the future usefulness of satellites in the performance of coordination and management functions related to the operation of flood control and other multipurpose projects in New England. Results on the data collection portion of the work are presented. The principal task was to develop statistics that demonstrate the relationship between conventional means of acquiring hydrologic data and the contribution made by using the satellite and its data collection platforms. Main interest was in determining the availability, reliability and usability of the data. Significant results on DCS show that the DCP's are reliable and useful and satellite data collection appears feasible on a nationwide basis.
The wind tunnel realtime computer system is a distributed data gathering system that features a master computer subsystem, a high speed data gathering subsystem, a quick look dynamic analysis and vibration control subsystem, an analog recording back-up subsystem, a pulse code modulation (PCM) on-board subsystem, a communications subsystem, and a transducer excitation and calibration subsystem. The subsystems are married to the master computer through an executive software system and standard hardware and FORTRAN software interfaces. The executive software system has four basic software routines. These are the playback, setup, record, and monitor routines. The standard hardware interfaces along with the software interfaces provide the system with the capability of adapting to new environments.
The mixed-fuels program examined included two major phases: the development of a reformer that would provide an onboard source of hydrogen, and the testing of induction systems and mixed fuels on a conventional V8 engine to verify the concept and define the system's potential. The discussion is limited to the engine testing phase. The testing program is reviewed and the effectiveness of an IDAC data acquisition system in supporting the engine testing program is demonstrated. The data system's application is illustrated by examples.
The paper describes how an integrated system of engineering computer programs can be built using a standard commercially available operating system. The discussion opens with an outline of the auxiliary functions that an operating system can perform for a team of engineers involved in a large and complex task. An example of a specific integrated system is provided to explain how the standard operating system features can be used to organize the programs into a simple and inexpensive but effective system. Applications to an aircraft structural design study are discussed to illustrate the use of an integrated system as a flexible and efficient engineering tool. The discussion concludes with an engineer's assessment of an operating system's capabilities and desirable improvements.