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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 487 records · Page 27

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NASA NTRS1974

Water-management models in Florida from ERTS-1 data

A prototype multiparameter data acquisition network, installed and operated by the U.S. Geological Survey is a viable approach for obtaining near real-time data needed to solve hydrologic problems confronting nearly 2.5 million residents of south Florida. Selected water quantity and quality data obtained from ground stations are transmitted for relay via ERTS-1 to NASA receiving stations in virtual real time. This data relay system has been very reliable and, by coupling the ground information with ERTS imagery, a modeling technique is available for water resource management in south Florida. An ecological model has been designed for the Shark River Slough in Everglades National Park.

Higer, A. L.↗

NASA NTRS1975

Apollo Soyuz Test Project Weights and Mass Properties Operational Management System

The Apollo Soyuz Test Project (ASTP) Weights and Mass Properties Operational Management System was established to assure a timely and authoritative method of acquiring, controlling, generating, and disseminating an official set of vehicle weights and mass properties data. This paper provides an overview of the system and its interaction with the various aspects of vehicle and component design, mission planning, hardware and software simulations and verification, and real-time mission support activities. The effect of vehicle configuration, design maturity, and consumables updates is discussed in the context of weight control.

Collins, M. A., Jr.↗

NASA NTRS1978

Automated meteorological data from commercial aircraft via satellite: Present experience and future implications

A low-cost communications system to provide meteorological data from commercial aircraft, in neat real-time, on a fully automated basis has been developed. The complete system including the low profile antenna and all installation hardware weighs 34 kg. The prototype system was installed on a B-747 aircraft and provided meteorological data (wind angle and velocity, temperature, altitude and position as a function of time) on a fully automated basis. The results were exceptional. This concept is expected to have important implications for operational meteorology and airline route forecasting.

Steinberg, R.↗

NASA NTRS1978

Reference manual for the Langley Research Center flight simulation computing system

The researchers at the Langley Research Center Flight Simulation Computing System are provided with an advanced real-time digital simulation capability. This capability is controlled at the user interface level by the Real Time Simulation Supervisor. The Supervisor is a group of subprograms loaded with a simulation application program. The Supervisor provides the interface between the application program and the operating system, and coordinates input and output to and from the simulation hardware. The Supervisor also performs various utility functions as required by a simulation application program.

Cleveland, J. I., II↗

NASA NTRS1978

Automated meteorological data from commercial aircraft via satellite - Present experience and future implications

The National Aeronautics and Space Administration has developed a low-cost communications system to provide meteorological data from commercial aircraft, in near real-time, on a fully automated basis. The complete system including the low profile antenna and all installation hardware weighs 34 kg. The prototype system has been installed on a Pan American B-747 aircraft and has been providing meteorological data (wind angle and velocity, temperature, altitude and position as a function of time) on a fully automated basis for the past several months. The results have been exceptional. This concept is expected to have important implications for operational meteorology and airline route forecasting.

Steinberg, R.↗

NASA NTRS1980

Use of a digital tone extractor for real-time phase analysis

A digital tone extractor which monitors the phase integrity of a VLBI recording system in real time was developed. The digital tone extractor monitors phase calibrator tones injected at the antenna and tracks their phase as a function of time. It is capable of maintaining 0.001 cycle phase accuracy over the course of a VLBI experiment in accordance with the accuracy requirements of centimeter VLBI work. This real time VLBI system monitor is a safeguard against most instrumental breakdowns and operator errors.

Sigman, E.↗

NASA NTRS1981

A time lag study of the vertical motion simulator computer system

A study was performed to evaluate an experimental method to determine time lags in real-time computer systems as the one associated with the Vertical Motion Simulator at Ames Research Center. The approach was to use an ordinary frequency analyzer to measure the phase difference between inputs and outputs of the computer system. The various elements of the program and computational architecture were modeled. Various factors, such as computer frame time and input frequency, were varied so that they were representative of the operational use of the simulator facilities. Experimentally determined results were compared with predictions derived from the simulation models. The results indicate that the frequency analyzer can be readily used to evaluate time lags in systems of this type. Differences between predicted and measured phase values indicate that the hardware and software imparts a time lag of about 5 msec to this facility.

Cleveland, W. B.↗

NASA NTRS1982

A real-time dynamic spacecraft simulator for the LANDSAT-D mission

A real time dynamic simulator for LANDSAT D was developed and has played an integral role in the development and validation of both the ground control system and of the on-board flight software. The simulator utilized an electronic replica of the spacecraft on-board computer and data handling hardware interfaced to a VAX 11/780 computer and simulation software. Key features of the simulator design are a modular software architecture tailored to the VAX/VMS real time capabilities, a microprocessor controlled interface between the VAX and the flight hardware replica, complete simulation of the spacecraft and NASA network communication links, and a flexible and powerful scenario structuring and operator control capability. The design goals and trade-offs, software, and hardware design are summarized. The application of the simulator to the validation of both the ground systems and on-board software is reviewed in detail.

Coffin, A. R.↗

NASA NTRS1983

Development and evaluation of a Kalman-filter algorithm for terminal area navigation using sensors of moderate accuracy

Translational state estimation in terminal area operations, using a set of commonly available position, air data, and acceleration sensors, is described. Kalman filtering is applied to obtain maximum estimation accuracy from the sensors but feasibility in real-time computations requires a variety of approximations and devices aimed at minimizing the required computation time with only negligible loss of accuracy. Accuracy behavior throughout the terminal area, its relation to sensor accuracy, its effect on trajectory tracking errors and control activity in an automatic flight control system, and its adequacy in terms of existing criteria for various terminal area operations are examined. The principal investigative tool is a simulation of the system.

Kanning, G.↗

NASA NTRS1983

Mixing 4D equipped and unequipped aircraft in the terminal area

The problem of mixing four-dimensional (4D) equipped aircraft (aircraft equipped with on-board guidance systems that can predict and control the touchdown-time of an aircraft to an accuracy of a few seconds throughout the descent) with unequipped aircraft in the terminal area has been investigated via a real-time air traffic control simulation study. The objective of this study was to develop scheduling algorithms and operational procedures for various traffic mixes that ranged from 25 percent to 75 percent 4D equipped aircraft. Results indicate substantial reduction in controller workload and an increase in orderliness when more than 25 percent of the aircraft are 4D equipped. Moreover, this is accomplished without increasing the workload or adding delays for the unequipped aircraft.

Tobias, L.↗

NASA NTRS1983

A Kalman filter algorithm for terminal-area navigation with sensors of moderate accuracy

Translational state estimation in terminal area operations, using a set of commonly available position, air data, nd acceleration sensors, is described. Kalman filtering is applied to obtain maximum estimation occuracy from the sensors but feasibility in real-time computations requires a variety of approximations and devices aimed at minimizing the required computation time with only negligible loss of accuracy. Accuracy behavior throughout the terminal area, its relation to sensor accuracy, its effect on trajectory tracking errors and control activity in an automatic flight control system, and its adequacy in terms of existing criteria for various terminal area operations are examined. The principal investigative tool is a simulation of the system. Previously announced in STAR as N83-29193

Cicolani, L. S.↗

NASA NTRS1983

Development of real-time ATC simulation facility

The Flight Transportation Laboratory has developed a real time interactive Air Traffic Control simulation facility designed to provide a versatile and easy to use tool for research and experimentation involving air traffic control. The facility uses a VAX-11/750 as the central computer. The SANDERS GRAPHICS-7 display system is used to simulate air traffic control displays. Pseudo-pilot displays are provided on Texas Instruments TI940 video terminals. Finally, a custom designed audio system driven by a Z-80 and interfaced with the VAX provides voice communication between the air traffic controllers and the pseudo-pilots. The audio system provides computer controlled voice disguising and thus allows each aircraft to have its own audio characteristics and provides an added realism to the experiment. The facility can accommodate multiple controller stations and pseudo-pilot stations. Each station is manned by a single operator who has a large repertoire of commands with which to control his/her display and the simulated aircraft under his/her jurisdiction. An additional console and a distinct set of commands allow full controllability of the simulation environment by the experimenter in real time.

Pararas, J.↗

NASA NTRS1983

Real-time digital processing of SAR data

Current SAR data processing techniques for spaceborne SAR systems utilize commercial equipment to carry the computation load. For a data set such as SEASAT, the resulting throughput rate is two to three orders of magnitude slower than real time. Such rates impede the progress of scientific investigations and preclude the potential for any practical operational SAR mission. It is suggested that a set of special-purpose hardware could be designed for efficient SAR data processing so that real time rates are both practical and affordable.

Bickwell, T. J.↗

NASA NTRS1983

Real-time MST radar signal processing using a microcomputer running under FORTH

Data on power, correlation time, and velocity were obtained at the Urbana radar using microcomputer and a single floppy disk drive. This system includes the following features: (1) measurement of the real and imaginary components of the received signal at 20 altitudes spaced by 1.5 km; (2) coherent integration of these components over a 1/8-s time period; (3) continuous real time display of the height profiles of the two coherently integrated components; (4) real time calculation of the 1 minute averages of the power and autocovariance function up to 6 lags; (5) output of these data to floppy disk once every 2 minutes; (6) display of the 1 minute power profiles while the data are stored to the disk; (7) visual prompting for the operator to change disks when required at the end of each hour of data; and (8) continuous audible indication of the status of the interrupt service routine. Accomplishments were enabled by two developments: the use of a new correlation algorithm and the use of the FORTH language to manage the various low level and high level procedures involved.

Bowhill, S. A.↗

NASA NTRS1983

Real-time pilot guidance system for improved flight-test maneuvers

The Dryden Flight Research Facility has developed a pilot trajectory guidance system that is intended to increase the accuracy of flight-test data and decrease the time required to achieve and maintain desired test conditions, or both. The system usually presented to the pilot computed differences between reference or desired and actual flight state conditions. The pilot then used a cockpit display as an aid to acquire and hold desired test conditions. This paper discusses various flight-test maneuvers and the quality of data obtained using the guidance system. Some comparisons are made between the quality of maneuvers obtained with and without the system. Limited details of the guidance system and algorithms used are included. In general, the guidance system improved the quality of the maneuvers and trajectories flown, as well as allowing trajectories to be flown that would not have been possible without the system. This system has moved from the developmental stage to full operational use in various Dryden research and test aircraft.

Meyer, R. R., Jr.↗

NASA NTRS1983

Man's role in a remote orbital servicing system

The Remote Orbital Servicing System (ROSS), a focal point for NASA research in automation and robotics, is discussed in terms of the role of man in such a system. In the supervisory control mode, the ROSS operator inputs high-level goals to a strategic (nonreal-time) planner which then passes the plan or series of actions to a tactical (real-time) planner which executes the plan. Using directed control, man makes more specific commands to perform strategic planning with or without the use of the automated strategic planner. Shared computer/manual control will require a multifunction interactive display. At the teleoperator control level, a hand controller is used to command the ROSS manipulator and end effectors.

Pennington, J. E.↗

NASA NTRS1983

Transient responses of phosphoric acid fuel cell power plant system

An analytical and computerized study of the steady state and transient response of a phosphoric acid fuel cell (PAFC) system was completed. Parametric studies and sensitivity analyses of the PAFC system's operation were accomplished. Four non-linear dynamic models of the fuel cell stack, reformer, shift converters, and heat exchangers were developed based on nonhomogeneous non-linear partial differential equations, which include the material, component, energy balance, and electrochemical kinetic features. Due to a lack of experimental data for the dynamic response of the components only the steady state results were compared with data from other sources, indicating reasonably good agreement. A steady state simulation of the entire system was developed using, nonlinear ordinary differential equations. The finite difference method and trial-and-error procedures were used to obtain a solution. Using the model, a PAFC system, that was developed under NASA Grant, NCC3-17, was improved through the optimization of the heat exchanger network. Three types of cooling configurations for cell plates were evaluated to obtain the best current density and temperature distributions. The steady state solutions were used as the initial conditions in the dynamic model. The transient response of a simplified PAFC system, which included all of the major components, subjected to a load change was obtained. Due to the length of the computation time for the transient response calculations, analysis on a real-time computer was not possible. A simulation of the real-time calculations was developed on a batch type computer. The transient response characteristics are needed for the optimization of the design and control of the whole PAFC system. All of the models, procedures and simulations were programmed in Fortran and run on IBM 370 computers at Cleveland State University and the NASA Lewis Research Center.

Lu, Cheng-Yi↗

NASA NTRS1980

Edge smoothing for real-time simulation of a polygon face object system as viewed by a moving observer

The visual system within an aircraft flight simulation system receives flight data and terrain data which is formated into a buffer memory. The image data is forwarded to an image processor which translates the image data into face vertex vectors Vf, defining the position relationship between the vertices of each terrain object and the aircraft. The image processor then rotates, clips, and projects the image data into two-dimensional display vectors (Vd). A display generator receives the Vd faces, and other image data to provide analog inputs to CRT devices which provide the window displays for the simulated aircraft. The video signal to the CRT devices passes through an edge smoothing device which prolongs the rise time (and fall time) of the video data inversely as the slope of the edge being smoothed. An operational amplifier within the edge smoothing device has a plurality of independently selectable feedback capacitors each having a different value. The values of the capacitors form a series which doubles as a power of two. Each feedback capacitor has a fast switch responsive to the corresponding bit of a digital binary control word for selecting (1) or not selecting (0) that capacitor. The control word is determined by the slope of each edge. The resulting actual feedback capacitance for each edge is the sum of all the selected capacitors and is directly proportional to the value of the binary control word. The output rise time (or fall time) is a function of the feedback capacitance, and is controlled by the slope through the binary control word.

Lotz, Robert W.↗