Engineering topics

Mccarthy, J.

Publications and source records attributed to Mccarthy, J..

31 records · Page 2

NASA NTRS1981

Abundances of argon, sulfur, and neon in six galactic H II regions from infrared forbidden lines

Airborne measurements of the Ar II (6.99 micron) and S III (18.71 micron) forbidden lines for six compact H II regions are presented, as well as ground-based 2-4 micron and 8-13 micron spectroscopy if not already published. From these data and radio data, lower limits to the elemental abundances of Ar, Ne, and S are deduced. G29.9-0.0, at 5 kpc from the galactic center, is overabundant in all these elements. The other five regions (at distances 6-13 kpc from the center) mainly appear to be consistent with standard abundances, with the exception of G75.84 + 0.4 at 10 kpc from the galactic center, which is overabundant in S. However, preliminary results on G12.8-0.2 at 6 kpc from the galactic center suggest a possible underabundance. A large statistical sample of H II regions is required in order to determine if there is a radial gradient in the heavy element abundances of the Galaxy.

Herter, T.↗

NASA NTRS1981

Assessment of advanced coal gasification processes

A technical assessment of the following advanced coal gasification processes is presented: high throughput gasification (HTG) process; single stage high mass flux (HMF) processes; (CS/R) hydrogasification process; and the catalytic coal gasification (CCG) process. Each process is evaluated for its potential to produce synthetic natural gas from a bituminous coal. Key similarities, differences, strengths, weaknesses, and potential improvements to each process are identified. The HTG and the HMF gasifiers share similarities with respect to: short residence time (SRT), high throughput rate, slagging, and syngas as the initial raw product gas. The CS/R hydrogasifier is also SRT, but is nonslagging and produces a raw gas high in methane content. The CCG gasifier is a long residence time, catalytic, fluidbed reactor producing all of the raw product methane in the gasifier.

Mccarthy, J.↗

NASA NTRS1981

An airport wind shear detection and warning system using Doppler radar: A feasibility study

A feasibility study was conducted to determine whether ground based Doppler radar could measure the wind along the path of an approaching aircraft with sufficient accuracy to predict aircraft performance. Forty-three PAR approaches were conducted, with 16 examined in detail. In each, Doppler derived longitudinal winds were compared to aircraft measured winds; in approximately 75 percent of the cases, the Doppler and aircraft winds were in acceptable agreement. In the remaining cases, errors may have been due to a lack of Doppler resolution, a lack of co-location of the two sampling volumes, the presence of eddy or vortex like disturbances within the pulse volume, or the presence of point targets in antenna side lobes. It was further concluded that shrouding techniques would have reduced the side lobe problem. A ground based Doppler radar operating in the optically clear air, provides the appropriate longitudinal winds along an aircraft's intended flight path.

Mccarthy, J.↗

NASA NTRS1980

Doctor Fujita's microburst analysis at Chicago

Doppler radar measurements of an intense wind shear occurance are discussed. The data suggest the presence of an incredibly strong low level jet outflow component of the microburst event, reaching 60 knots only 50 meters above the surface. Evidence also suggests that microbursts more typically occur in very weak thunderstorms that have hardly reached thunderstorm stage.

Mccarthy, J.↗

NASA NTRS1980

An airport wind shear detection and warning system using Doppler radar

Two numerical models of aircraft performance are developed to relate atmospheric wind signals in wind-shear situations to aircraft response. Both models produce time histories of pitch angle, airspeed, height above the ground, and other parameters for simulating aircraft making precision approaches along a 3-deg glide slope to the runway. Simulations conducted using thunderstorm environment wind data indicate that the horizontal wind component is at least as important as the vertical component in determining aircraft response to wind shear. Obtaining quantitative measurements of aircraft approach or departure quality is found to depend on several factors, including the knowledge of winds along the expected flight track, clear-air detection in a quasi-horizontal path, and a near continuous estimate of approach deterioration due to shear conditions.

Mccarthy, J.↗

NASA NTRS1980

Instrumented aircraft verification of clear-air radar detection of low-level wind shear

A technique is described in which the longitudinal wind component at airports, measured by Doppler radar, is put through a Fourier transformation to produce an energy density spectrum. The result is multiplied by the aircraft response characteristics to produce quantitative data on aircraft performance in a wind shear situation. The Doppler radar measurements are made along the intended flight path. Two case studies, along a 3 deg approach path, are described from measurements in two modes: Lagrangian, where predictions were computed one range gate ahead of the plane, and Eulerian, where samples were measured instantaneously along the flight path. Wind data obtained every second were interpolated to fit a numerical model by using a cubic spline. Eulerian data were superior to Lagrangian data in terms of ranging, and nearly equal for wind speeds. Improvements in current 75% accuracy are noted to be possible with shrouded antennas to reduce sidelobes and use of Doppler radar with higher resolution to eliminate effects of small scale disturbances within the pulse volume.

Mccarthy, J.↗

NASA NTRS1979

Jet transport performance in thunderstorm wind shear conditions

Several hours of three dimensional wind data were collected in the thunderstorm approach-to-landing environment, using an instrumented Queen Air airplane. These data were used as input to a numerical simulation of aircraft response, concentrating on fixed-stick assumptions, while the aircraft simulated an instrument landing systems approach. Output included airspeed, vertical displacement, pitch angle, and a special approach deterioration parameter. Theory and the results of approximately 1000 simulations indicated that about 20 percent of the cases contained serious wind shear conditions capable of causing a critical deterioration of the approach. In particular, the presence of high energy at the airplane's phugoid frequency was found to have a deleterious effect on approach quality. Oscillations of the horizontal wind at the phugoid frequency were found to have a more serious effect than vertical wind. A simulation of Eastern flight 66, which crashed at JFK in 1975, served to illustrate the points of the research. A concept of a real-time wind shear detector was outlined utilizing these results.

Mccarthy, J.↗

NASA NTRS1978

Effect of wind turbulence and shear on landing performance of jet transports

Computer simulations of a Boeing 727 class aircraft landing in turbulence were developed by programming the longitudinal aircraft equations of motion into a digital computer with various input values of vertical and horizontal wind speeds. Turbulent wind data was fed to the computer in one-second intervals. The computer computed in one-second intervals the aircraft speed, altitude, horizontal distance traveled, rate-of-descent, pitch attitude, glide path angle (from edge of runway) and elevator angle. All computer runs were made in the 'stick-fixed' mode. The RMS values of altitude and velocity perturbations (from equilibrium) were found to be large when horizontal wind gusts had sinusoidal components at or near the phugoid (long period) frequency. Maximum RMS altitude deviations occurred when the vertical wind had sinusoidal components which were 1/10 to 1/5 of the phugoid frequency. When real wind data (obtained from NCAR Queen Air) were used as input winds good correlations were found to exist between RMS velocity perturbations and both horizontal and vertical wind shears.

Blick, E. F.↗

NASA NTRS1978

A spectral analysis of thunderstorm turbulence and jet transport landing performance

A description is presented of a study which examines not only wind shear, but considers the velocity spectrum of the wind, as it may affect the flight of an aircraft. A model reported by McCarthy and Blick (1976) and by Blick et al. (1978) is considered. The model simulated the approach performance of a Boeing 727-type aircraft, as affected by the time series winds measured along the aircraft's longitudinal axis. Attention is given to the model and its implications, wind shear simulations, and the use of the model in the study of a crash on June 24, 1975.

Mccarthy, J.↗

NASA NTRS1976

The radial variation of solar flare proton anisotropies observed in deep space on Pioneers 10 and 11

The anisotropy of solar-flare protons (greater than 3 MeV) was evaluated at the time of maximum for each of 24 events measured by Pioneers 10 and 11 and was observed to decrease gradually between 1 and 4.7 AU. Since diffusive streaming is related directly to the effective diffusion coefficient parallel to the interplanetary spiral magnetic field, these observations provide a measure of the radial dependence of interplanetary diffusion parameters. Analysis of these results suggests that the spiral field increases gradually with heliocentric distance. An expression is given for the radial dependence of that field.

Mccarthy, J.↗

NASA NTRS1975

The time and spatial behavior of solar flare proton anisotropies observed in deep space on Pioneers 10 and 11

The anisotropy of solar flare protons from the direction of the 'garden hose' magnetic field line has been analyzed for 24 events observed by the University of Chicago experiment on Pioneers 10 and 11 in 1972 and 1973. The anisotropy versus time profiles during individual events are in general consistent with diffusive propagation, but several cases are observed where the decay is better described by an exponential time decay. The anisotropy amplitude evaluated at the time of maximum intensity for each event shows evidence for a gradual decrease with increasing distance from the sun which is qualitatively consistent with diffusive propagation and suggests that the effective interplanetary diffusion coefficient parallel to the magnetic field increases slowly with heliocentric distance.

Mccarthy, J.↗

NASA NTRS1974

Anisotropies of galactic cosmic rays outside the orbit of earth measured on Pioneer 10

Preliminary results of observations of the directional distribution of cosmic rays being conducted by the University of Chicago experiment on the Pioneer 10 spacecraft are presented. The unusual geometry of the directional scan is described and some features of the response of a bidirectional coincidence telescope are discussed. Selected periods free from the presence of low-energy solar particles exhibit transient deviations from uniform directional distributions for the bidirectional flux of nuclei greater than 67 MeV/nucleon. These deviations are typically 2 to 4 (plus or minus 1) percent and are oriented very roughly in a N-S direction. Such nonuniformities observed with a bidirectional detector can only be due to even order terms in the angular distribution function.

Lentz, G. A.↗

NASA NTRS1973

Research in mathematical theory of computation

Research progress in the following areas is reviewed: (1) new version of computer program LCF (logic for computable functions) including a facility to search for proofs automatically; (2) the description of the language PASCAL in terms of both LCF and in first order logic; (3) discussion of LISP semantics in LCF and attempt to prove the correctness of the London compilers in a formal way; (4) design of both special purpose and domain independent proving procedures specifically program correctness in mind; (5) design of languages for describing such proof procedures; and (6) the embedding of ideas in the first order checker.

Mccarthy, J.↗