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At least 1,333 records · Page 74

On the location of acid-hydrolysable carbon in lunar soil fines

Soil fines exposed on the lunar surface accumulate small metallic iron particles and solar wind-derived carbon. In previous work, it has been suggested that an intimate association exists between one particular carbon phase, hydrolysable carbon, and very fine iron droplets, where the carbon is in solid solution in the iron. The earlier hypothesis of a constant carbon in iron concentration across a broad range of droplet sizes is testable by combining hydrolysable carbon determinations with a variety of magnetic measurements sensitive to different droplet diameters. New measurements of ferromagnetic resonance response on density and magnetic separates from size fractions of soil 12023 are interpreted as evidence that hydrolysable carbon is preferentially associated with the larger, magnetically stable single-domain iron particles rather than with the smaller superparamagnetic droplets. For the former, there is a quite uniform ratio of iron to carbon both within a series of separates from a single soil, and among soils of widely varying FeO content.

Fallick, A. E.↗

On the adequacy of the fixed locations of the surface-based international network for inferring interannual ozone variability

The influence of the geographical distribution and the number of the surface stations in the ozone detecting network on changes in global ozone inferred from the surface measurements is investigated by comparison with information obtained from satellite backscattered UV observations on the Nimbus 4 with nearly complete global coverage for the period 1970-1972. Results show that the geographical distribution of the stations does not properly represent different latitudes. While the number of stations in the north temperate zone appears adequate to represent monthly ozone averages to within 0.5% except during the early phase of the Northern Hemisphere spring maximum, the resultant error in the derived change in north temperature zone ozone between 1970-1972 is 0.5%. In the tropical and south temperate zones the smaller number of stations reduces precision, and the ozone averages for use in deriving seasonal variability and trends are uncertain by about 1%. However, in the south temperature zone, the average from the sample may differ as much as 5% in some months from the averages derived from the full set. It is concluded that the resulting uncertainty in the global averages is comparable in size to typical yearly changes.

Heath, D. F.↗

Dielectric Scanning Locates Voids in Glass Foam

Capacitive probes succeed where X-ray and ultrasonic equipment do not. Crossbar switching of pairs of conductors enables detection of dielectric inhomogeneities in selected small volume elements of slab of material. Large void in sample detected as low capacitance reading for volume element containing void. Applicable in nondestructive testing of other dielectric objects for internal defects that exhibit dielectric inhomogeneities.

Gammell, P. M.↗

Hole-Center Locating Tool

Tool alines center of new hold with existing hole. Tool marks center of new hole drilled while workpiece is in place. Secured with bolts while hole center marked with punch. Used for field installations where reference points unavailable or work area cramped and not easily accessible with conventional tools.

Senter, H. F.↗

Self-Locating Latch

New latch secures fitting without displacing fitting and without regard to where on latch fitting makes intitial contact.

Gibson, J.↗

A study of optimum cowl shapes and flow port locations for minimum drag with effective engine cooling, volume 1

The contributions to the cruise drag of light aircraft arising from the shape of the engine cowl and the forward fuselage area and also that resulting from the cooling air mass flow through intake and exhaust sites on the nacelle were analyzed. The methods employed for the calculation of the potential flow about an arbitrary three dimensional body are described with modifications to include the effects of boundary layer displacement thickness, a nonuniform onset flow field (such as that due to a rotating propeller), and the presence of air intakes and exhausts. A simple, reliable, largely automated scheme to better define or change the shape of a body is also presented. A technique was developed which can yield physically acceptable skin friction and pressure drag coefficients for isolated light aircraft bodies. For test cases on a blunt nose Cessna 182 fuselage, the technique predicted drag reductions as much as 28.5% by body recontouring and proper placements and sizing of the cooling air intakes and exhausts.

Fox, S. R.↗

The location and scope of geographic remote sensing training in the United States

Maps displaying the distribution of graduate departments of geography in the United States and enrollments in remote sensing courses in all geography departments during the past two calendar years were compiled. It was anticipated that the two distributions would show a marked similarity since remote sensing is a relatively new geographic tool requiring specialized training to use as well as equipment not normally found in most geography departments. Thus only the larger graduate departments can afford to devote time and resources to this specialty. A broad correspondence does exist between the graduate departments of geography and the courses in remote ensing. However, the correlation is far from complete and the exceptions are frequent and large enough to cast doubt upon the accuracy of the original hypothesis. Whereas many large departments do offer courses in remote sensing, many smaller colleges and universities do also. A number of possible explanations can be offered for the discrepancies: (1) course titles, (2) the liberal arts orientation of geography departments in many universities, (3) job-oriented skills which many smaller departments have emphasized, and (4) in the tight job market many new graduates of even the larger departments have had to accept position in smaller departments and colleges.

Hawley, A. J.↗

Effects of wing and tail location on the aerodynamic characteristics of an airplane for Mach numbers from 0.25 to 4.63

Experimental investigations have been conducted to determine the effect of wing vertical position and horizontal-tail vertical and axial position on the static aerodynamic characteristics of a wing-body horizontal-tail configuration. The configurations investigated included the wing in a high, mid, or low position on the body with the horizontal tail in each of these vertical positions as well as in three axial positions. The closest position of the horizontal tail to the wing essentially provided on all-wing configuration. In addition, tests were made for the three wing positions with the horizontal tail removed. The tests were made in three different wind tunnels to provide data for a Mach number range from 0.25 to 4.63. The purpose of the investigation was to illustrate the strong effects of interference flow fields as a function of geometry and flight regime. An analysis of the results indicate some arrangements that might lead to aerodynamic problems and others in which the interference flow fields might be favorably exploited. The results suggest that a coplanar concept with a translating horizontal tail could potentially minimize the aerodynamic changes with Mach number and provide more optimum performance over the Mach number range.

Spearman, M. L.↗

Storm-time changes of geomagnetic field at MAGSAT altitudes (325-550 Km) and their comparison with changes at ground locations

The values of H, X, Y, Z at MAGSAT altitudes were first expressed as residuals delta H, delta X, delta Y, delta Z after subtracting the model HMD, XMD, YMD, ZMC. The storm-time variations of H showed that delta H (Dusk) was larger (negative) than delta H (Dawn) and occurred earlier, indicating a sort of hysteresis effect. Effects at MAGSAT altitudes were roughly the same (10% accuracy) as at ground, indicating that these effects were mostly of magnetospheric origin. The delta Y component also showed large storm-time changes. The latitudinal distribution of storm-time delta H showed north-south asymmetries varying in nature as the storm progressed. It seems that the central plane of the storm-time magnetospheric ring current undergoes latitudinal meanderings during the course of the storm.

Parada, N. D. J.↗

A radio-frequency analysis of paraboloidal antennas located near diffracting fences

The cylindrical waves associated with the Sommerfeld solution for a diffracting half-plane are applied in the evaluation of the effects of secondary radiation on the focal-region-fields of paraboloids. A cross-correlation between the computed focal-region-fields and the feed-antenna-fields is then introduced to determine the modified radiation pattern of paraboloidal antennas. The half-plane solution is adapted to estimate the effects of a polygonal fence on 9-meter S-band and 3-meter S- and Ku-band antennas at the Merrit Island, Fl Spacecraft Tracking and Data Network Station.

Schmidt, R. F.↗

The source location of certain Jovian decametric radio emissions

Evidence is presented which supports the concept that certain of the Jovian decametric radio waves originate as northern hemisphere extraordinary mode cyclotron emissions. The wave signals received by Voyager 1 near 10 MHz shortly after the closest approach to Jupiter were found to exhibit cusps in the fringe pattern which can be attributed to Faraday rotation in the Io plasma torus. At nearly the same time, the wave polarization near 1 MHz was found to exhibit a sudden reversal of its rotation sense, indicating that the wave path for those frequencies had also become perpendicular to the magnetic field at the spacecraft. It was determined that the waves came from the northern hemisphere at progressively lower altitudes with increasing frequency, and if the source is assumed to be associated with an L = 6 field line, the emission appears to have occurred near the source cyclotron frequency somewhere in the local midnight sector. The evidence indicates that the source is at the Io flux tube and that the emitted wave mode must have been extraordinary. In addition, the emitted wave polarization must have been substantially noncircular which would require a low plasma density near the source, much like that which occurs with auroral kilometric radiation at the earth.

Calvert, W.↗

Vertical drop test of a transport fuselage section located forward of the wing

A Boeing 707 fuselage section was drop tested at the NASA Langley Research Center to measure structural, seat, and occupant response to vertical crack loads. Post-test inspection showed that the section bottom collapsed inward approximately 2 ft. Preliminary data traces indicated maximum normal accelerations of 20 g on the fuselage bottom, 10 to 12 g on the cabin floor, and 6.5 to 8 g in the pelvises of the anthropomorphic dummies.

Williams, M. S.↗

Estimating Location Parameters in a Mixture Model

Mixture models of the form h = sum to M terms, one for each positive integer from 1 to N lambda sub j f (j) sub theta sub j where theta sub j is a translation parameter are considered. An approach is discussed which makes use of a Caratheodory theorem on the trigonometric moment problem to determine M and theta sub j j = 1,2,...,M. This theorem is also applied to show that translates of many common distributions lead to identifiable mixtures.

Heydorn, R. P.↗