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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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NASA NTRS1987

Joint University Program for Air Transportation Research, 1984

The research conducted during 1984 under the NASA/FAA sponsored Joint University Program for Air Transportation Research is summarized. The Joint University Program is a coordinated set of three grants sponsored by NASA Langley Research Center and the Federal Aviation Administration, one each with the Massachusetts Institute of Technology, Ohio University, and Princeton University. Completed works, status reports, and bibliographies are presented for research topics, which include navigation, guidance, control and display concepts. An overview of the year's activities for each of the schools is also presented.

Morrell, Frederick R.↗
NASA NTRS1987

Masses, luminosities and dynamics of galactic molecular clouds

Star formation in galaxies takes place in molecular clouds and the Milky Way is the only galaxy in which it is possible to resolve and study the physical properties and star formation activity of individual clouds. The masses, luminosities, dynamics, and distribution of molecular clouds, primarily giant molecular clouds in the Milky Way are described and analyzed. The observational data sets are the Massachusetts-Stony Brook CO Galactic Plane Survey and the IRAS far IR images. The molecular mass and infrared luminosities of glactic clouds are then compared with the molecular mass and infrared luminosities of external galaxies.

Solomon, P. M.↗
NASA NTRS1987

Joint University Program for Air Transportation Research, 1985

Air transportation research being carried on at the Massachusetts Institute of Technology, Princeton University, and Ohio University is discussed. Global Positioning System experiments, Loran-C monitoring, inertial navigation, the optimization of aircraft trajectories through severe microbursts, fault tolerant flight control systems, and expert systems for air traffic control are among the topics covered.

Morrell, Frederick R.↗
NASA NTRS1987

The calibration of photographic and spectroscopic films. The utilization of the digital image processor in the determination of aging of the surf clam (Spisula solidissima)

The age of the surf clam (Spisula solidissima) can be determined with the use of the Digital Image Processor. This technique is used in conjunction with a modified method for aging, refined by John Ropes of the Woods Hole Laboratory, Massachusetts. This method utilizes a thinned sectioned chondrophore of the surf clam which contains annual rings. The rings of the chondrophore are then counted to determine age. By digitizing the chondrophore, the Digital Image Processor is clearly able to separate these annual rings more accurately. This technique produces an easier and more efficient way to count annual rings to determine the age of the surf clam.

Peters, Kevin A.↗
NASA NTRS1987

Where massive stars form - Associated radio H II regions and CO clouds in the northern Milky Way

The sites of massive star formation in molecular clouds are investigated by comparing high-resolution radio surveys of molecular and ionized gas emission in the Milky Way. CO emission maps from the Massachusetts-Stony Brook survey of the first Galactic quadrant are used to locate, in l, b, and v, the molecular clouds associated with radio recombination-line H II regions. It is found that the radio H II regions are typically associated with giant molecular clouds (GMCs) with diameters of 20-60 pc and virial masses of 100,000 to a million solar masses. The radio H II regions appear preferentially concentrated toward the centers of the GMCs, contrary to the 'blister' picture of massive star formation on cloud surfaces.

Waller, W. H.↗
NASA NTRS1986

The materials processing research base of the Materials Processing Center

An annual report of the research activities of the Materials Processing Center of the Massachusetts Institute of Technology is given. Research on dielectrophoresis in the microgravity environment, phase separation kinetics in immiscible liquids, transport properties of droplet clusters in gravity-free fields, probes and monitors for the study of solidification of molten semiconductors, fluid mechanics and mass transfer in melt crystal growth, and heat flow control and segregation in directional solidification are discussed.

Latanision, R. M.↗
NASA NTRS1988

VLBI geodesy - 2 parts-per-billion precision in length determinations for transcontinental baselines

VLBI was to make twenty-two independent measurements, between September 1984 and December 1986, of the length of the 3900-km baseline between the Mojave site in California and the Haystack/Westford site in Massachusetts. These experiments differ from the typical geodetic VLBI experiments in that a large fraction of observations is obtained at elevation angles between 4 and 10 deg. Data from these low elevation angles allow the vertical coordinate of site position, and hence the baseline length, to be estimated with greater precision. For the sixteen experiments processed thus far, the weighted root-mean-square scatter of the estimates of the baseline length is 8 mm.

Davis, J. L.↗
NASA NTRS1989

Probabilistic modeling of solar power systems

The author presents a probabilistic approach based on Markov chain theory to model stand-alone photovoltaic power systems and predict their long-term service performance. The major advantage of this approach is that it allows designers and developers of these systems to analyze the system performance as well as the battery subsystem performance in the long run and determine the system design requirements that meet a specified service performance level. The methodology presented is illustrated by using data for a radio repeater system for the Boston, Massachusetts, location.

Safie, Fayssal M.↗
NASA NTRS1990

Joint University Program for Air Transportation Research, 1988-1989

The research conducted during 1988 to 1989 under the NASA/FAA-sponsored Joint University Program for Air Transportation Research is summarized. The Joint University Program is a coordinated set of three grants sponsored by NASA Langley Research Center and the Federal Aviation Administration, one each with the Massachusetts Institute of Technology, Ohio University, and Princeton University. Completed works, status reports, and annotated bibliographies are presented for research topics, which include computer science, guidance and control theory and practice, aircraft performance, flight dynamics, and applied experimental psychology. An overview of the year's activities for each university is also presented.

Morrell, Frederick R.↗
NASA NTRS1989

Determinations of cloud liquid water in the tropics from the SSM/I

Upward-looking microwave radiometric observations were used to validate the SSM/I determinations, and also as a basis for the determination of new coefficients. Due to insufficiency of the initial four channel algorithm for cloud liquid water, the improved algorithm was derived from the CORRAD (the University of Massachusetts autocorrelation radiometer) measurements of cloud liquid water and the matching SSM/I brightness temperatures using the standard linear regression. The correlation coefficients for the possible four channel combinations, and subsequently the best and the worst combinations were determined.

Alishouse, John C.↗
NASA NTRS1990

A simple dynamic engine model for use in a real-time aircraft simulation with thrust vectoring

A simple dynamic engine model was developed at the NASA Ames Research Center, Dryden Flight Research Facility, for use in thrust vectoring control law development and real-time aircraft simulation. The simple dynamic engine model of the F404-GE-400 engine (General Electric, Lynn, Massachusetts) operates within the aircraft simulator. It was developed using tabular data generated from a complete nonlinear dynamic engine model supplied by the manufacturer. Engine dynamics were simulated using a throttle rate limiter and low-pass filter. Included is a description of a method to account for axial thrust loss resulting from thrust vectoring. In addition, the development of the simple dynamic engine model and its incorporation into the F-18 high alpha research vehicle (HARV) thrust vectoring simulation. The simple dynamic engine model was evaluated at Mach 0.2, 35,000 ft altitude and at Mach 0.7, 35,000 ft altitude. The simple dynamic engine model is within 3 percent of the steady state response, and within 25 percent of the transient response of the complete nonlinear dynamic engine model.

Johnson, Steven A.↗
NASA NTRS1990

Dynamics and control of multipayload platforms - The Middeck Active Control Experiment (MACE)

A flight experiment entitled the Middeck Active Control Experiment (MACE) proposed by the Space Engineering Research Center (SERC) at the Massachusetts Institute of Technology is described. The objective of this program is to investigate and validate the modeling of the dynamics of an actively controlled flexible, articulating, multibody platform free floating in zero gravity. A rationale and experimental approach for the program are presented. The rationale shows that on-orbit testing, coupled with ground testing and a strong analytical program, is necessary in order to fully understand both how flexibility of the platform affects the pointing problem, as well as how gravity perturbs this structural flexibility causing deviations between 1-and 0-gravity behavior. The experimental approach captures the essential physics of multibody platforms, by identifying the appropriate attributes, tests, and performance metrics of the test article, and defines the tests required to successfully validate the analytical framework.

Miller, David W.↗
NASA NTRS1989

Microwave measurements of ocean currents for the SAXON experiment

Measurements of ocean surface currents carried out during the SAXON experiment using the University of Massachusetts stepped-frequency Delta-K radar (SFDKR) are presented. The measurement site was the Chesapeake light tower situated in the north Atlantic Ocean, 15 km off the coast of Virginia Beach, Virginia. The radar was placed on a platform 26 m above mean sea level. Measurements were made at grazing angles between 3 and 10 deg. A nearly uninterrupted record of ocean current velocity was obtained for a 26-day period. The measurement dependence on various system and hydrodynamic parameters and a comparison with an independent in-situ current measurement (EM current meter) are presented. Experimental results show that the Delta K spectrum with a distinguishable resonant line can be measured under all weather conditions, from calm seas with large swells to the fully developed seas occurring under winds as high as 20 ms-1. The only parameter that needs to be adjusted in real time is the frequency separation, Delta f, which has to be modified according to the varying shape of the ocean wave spectrum. Currents could not be accurately measured for very low wind conditions, even though resonant lines were present in the Delta K spectrum. The SFDKR can accurately measure wind-driven surface currents for wide range of wind conditions.

Popstefanija, Ivan↗
NASA NTRS1990

Comparison between two vegetation indices for measuring different types of forest damage in the north-eastern United States

The relative effectiveness of the Landsat TM-derived normalized difference vegetative index (NDVI) and the short-wave IR to NIR ratio (SWIR/NIR) index was examined in measurements of different types of damage in several forest communities. The forests examined included a site with well-defined fir waves in New Hampshire, a site undergoing well-documented coniferous forest decline in Vermont, and predominantly deciduous regions in Vermont and northwestern Massachusetts seriously impacted by pear thrips. Both NDVI and SWIR/NIR images were produced for each area. Results demonstrated that the SWIR/NIR index was superior to NDVI in distinguishing between high and low conifer damage at both fir-wave and forest decline sites; high and low deciduous-forest damage sites were easily separable using either NDVI or SWIR/NIR, but the NDVI was superior in separation between medium and low deciduous damage.

Vogelmann, J. E.↗
NASA NTRS1991

Effects of atmospheric modeling errors on determinations of baseline vectors from very long baseline interferometry

An investigation is conducted in order to expose errors in the formula for the elevation angle dependence of the hydrostatic atmospheric propagation delay, called the mapping function. A series of special VLBI experiments that involve a large fraction of group delay data from very low elevation angles are performed. Twenty-two experiments, each 26 hours in duration, were performed using VLBI antennas at Goldstone, California and at Westford, Massachusetts. Elevation angle cutoff tests were used to examine the contribution of these errors to the estimates of the vertical coordinate of site position. This contribution is determined to be about 19 mm. It is also found that, for the spacing of 1-2 months between experiments, the mapping function errors do not exhibit a coherent annual signature, but appear to be random in the long term.

Davis, J. L.↗
NASA NTRS1991

Radiative transfer in planetary atmospheres: Submillimeter-wave spectroscopy of comets

During 1990, a significant step was made in asertaining the molecular composition of comets by our Planetary Astronomy group at the University of Massachusetts. We obtained several exciting new detections of submillimeter wave spectral lines from molecules in the coma of Comet Levy (1990c) using the 10m telescope of the Caltech Submillimeter Observatory, located on Mauna Kea. The molecules HCN, formaldahyde, and methanol were all detected in abundances that make them important minor constituents of the nucleus. Moreover, the emission was so strong that, for the first time, it was possible to map the distribution of these species in the coma and study their behavior as they flow outwards from the nucleus.

Schloerb, F. Peter↗
NASA NTRS1991

Joint University Program for Air Transportation Research, 1990-1991

The goals of this program are consistent with the interests of both NASA and the FAA in furthering the safety and efficiency of the National Airspace System. Research carried out at the Massachusetts Institute of Technology (MIT), Ohio University, and Princeton University are covered. Topics studied include passive infrared ice detection for helicopters, the cockpit display of hazardous windshear information, fault detection and isolation for multisensor navigation systems, neural networks for aircraft system identification, and intelligent failure tolerant control.

Morrell, Frederick R.↗
NASA NTRS1992

High accuracy fuel flowmeter. Phase 2C and 3: The mass flowrate calibration of high accuracy fuel flowmeters

A facility for the precise calibration of mass fuel flowmeters and turbine flowmeters located at AMETEK Aerospace Products Inc., Wilmington, Massachusetts is described. This facility is referred to as the Test and Calibration System (TACS). It is believed to be the most accurate test facility available for the calibration of jet engine fuel density measurement. The product of the volumetric flow rate measurement and the density measurement, results in a true mass flow rate determination. A dual-turbine flowmeter was designed during this program. The dual-turbine flowmeter was calibrated on the TACS to show the characteristics of this type of flowmeter. An angular momentum flowmeter was also calibrated on the TACS to demonstrate the accuracy of a true mass flowmeter having a 'state-of-the-art' design accuracy.

Craft, D. William↗