Brief Note on the Radiation Belts of the Earth
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Vanallen, J. A.↗
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Note on the semi-annual effect in the thermosphere
The semi-annual variation in the thermospheric density is discussed in terms of the spatial and temporal variations in the solar heat input. Two heat sources are considered: the solar heat input associated with the semi-annual migration of the sun, and the auroral heat associated with the semi-annual component in magnetic storms. It is shown that the relatively large global component in the semi-annual effect of the total mass density can be explained by the lack of advective loss which otherwise damps the latitude dependent components in the annual and semi-annual variations, and the significant latitude dependence in the semi-annual variations of composition and temperature can be tied to the diffusion process which is induced by the thermospheric circulation.
Volland, H.↗
Data user's note: Apollo 15 lunar photography
Brief descriptions are given of the Apollo 15 mission objectives, photographic equipment, and photographic coverage and quality. The lunar photographic tasks were: (1) ultraviolet photography of the earth and moon; (2) photography of the gegenschein from lunar orbit; (3) service module orbital photographic tasks; and (4) command module photographic tasks.
Cameron, W. S.↗
Supplementary notes on sea surface temperature anomalies and model-generated meteorological histories
In seasonal computations, the Mintz-Arakawa two-level model is found to be sensitive to a minor alteration in the computational program. Effects of the program change on monthly mean sea level pressure fields are small in the first month, but large in the second and third months, although the meteorological histories generated by both the original and modified programs are equally credible. The inherited effects of a transient (one month) sea surface temperature (SST) anomaly on the computed monthly mean sea level pressure fields over a period of a season are about as large in absolute magnitude as those generated in the model by a persistent (seasonal) SST anomaly. The effects of a transient SST anomaly in the North Pacific Ocean on monthly and seasonal temperature and precipitation in the eastern United States may be large enough to produce a change of one or two class intervals in these predicted weather elements. The model-generated precipitation in the equatorial region is also found to be sensitive to the sea surface temperature field in the North Pacific.
Spar, J.↗
A note on the interference of two collinear cracks in a cylindrical shell
A stress analysis of a pressurized shallow cylindrical shell containing two collinear axial cracks of equal length was conducted. The mathematical relationships for conducting the stress analysis are developed. Graphs are presented to show the stress intensity factor ratio in the cylindrical shell and the bending components of the stress intensity factor ratio.
Erdogan, F.↗
Notes for the improvement of a remote sensing multispectral data non-supervised classification and mapping technique
Examined are: (1) the sequential clustering technique for the unsupervised automatic classification and mapping of earth resources satellite data, (2) theoretical analysis of the tests which were used, and (3) derivation of an alternative set of tests and their necessary algorithm.
Dalton, C. C.↗
An Analysis of Airline Costs. Lecture Notes for MIT Courses. 16.73 Airline Management and Marketing
The cost analyst must understand the operations of the airline and how the activities of the airline are measured, as well as how the costs are incurred and recorded. The data source is usually a cost accounting process. This provides data on the cumulated expenses in various categories over a time period like a quarter, or year, and must be correlated by the analyst with cumulated measures of airline activity which seem to be causing this expense.
Simpson, R. W.↗
Technology for design of transport aircraft. Lecture notes for MIT courses: Seminar 1.61 freshman seminar in air transportation and graduate course 1.201, transportation systems analysis
The design parameters which determine cruise performance for a conventional subsonic jet transport are discussed. It is assumed that the aircraft burns climb fuel to reach cruising altitude and that aeronautical technology determines the ability to carry a given payload at cruising altitude. It is shown that different sizes of transport aircraft are needed to provide the cost optimal vehicle for different given payload-range objectives.
Simpson, R. W.↗
Observational evidence relating to a recent theory on the origin of the universal X-ray background /Research note/.
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Mack, J. E.↗
On the minimum intensity of the Na D2-5890 A line in sunspot umbra /Research note/.
The largest spot in the group Rome 5847 was observed on two successive days (July 6 and 7, 1970), and the data were reduced separately. Taking the instrumental parasitic light contamination (Wyller and Fay, 1972) into account, the value of the line-to-continuum intensity ratio is found to be 0.033 plus or minus 0.05 by two methods.
Fay, T.↗
A note on the geomagnetic spectrum.
Unpublished evidence is presented for a line in the H component magnetic power spectra belonging to the low frequency components of the geomagnetic field investigated by Currie (1966). This line is similar to the 54-day line detected by Fraser-Smith (1971) in spectra of the Ap index and its implications are discussed.
Currie, R. G.↗
Note on variations in the 'quasi-biennial' oscillation.
Data compiled since 1962 are examined in an effort to quantify further the observed variations in the 'quasi-biennial' oscillation (QBO). A further study of temperatures and zonal winds is conducted for Canton Island, Ascension Island, and Balboa, C.Z. Statistics are derived for the period of record prior to 1962 and for that subsequent to 1962. The results of the investigation suggest that the QBO has remained in roughly geostrophic equilibrium since it was first observed.-
Mcinturff, R. M.↗
The Haveroe ureilite - Petrographic notes.
Review of the mineralogy and texture of the Haveroe and of some of the six other known ureilites, and assessment of the implications of their observed characteristics. In common with other ureilites, Haveroe shows mineralogical and textural evidence of preterrestrial shock. The olivines and metal grains have been recrystallized, the fabric includes angular voids, and graphite-rich areas are present that have been partially converted to diamonds with some indication of lonsdaleite. On the basis of such features, a subdivision of ureilites into particular types is proposed.
Marvin, U. B.↗
Note on the error signal of block quantizers.
Demonstration that the error signal incurred by block quantizing stationary data is nonstationary under some conditions. Examples are presented which indicate that the mean square error is largest at the block edges. When block quantizers are used to encode pictures at low bit rates, this effect tends to make the block edges visible in the reconstructed picture.
Tasto, M.↗
A note on signal enhancement for dual magnetometer systems.
Demonstration of the value of cross-correlation signal enhancement achieved by means of a dual magnetometer system. A unique feature of a dual magnetometer system is, as pointed out by Ness et al. (1971), the opportunity it allows for signal enhancement by using cross-correlation techniques developed in statistical communication theory. Their use is shown to make it possible to overcome the limitations that the intrinsic sensor ambient noise and the measurement-contaminating spacecraft field fluctuations impose upon the signal detection performance of a single magnetometer.
Ness, N. F.↗
A note on the relations between true and eccentric anomalies in the two-body problem.
Two remarkably simple formulas are proposed for relating the eccentric and true anomalies in the two-body problem at no numerical trouble, no matter what the values of the angles are. The problem of the maximum difference between the two angles is also considered.
Broucke, R.↗
Note on the semiannual effect in the thermosphere.
There are two external heat sources known that oscillate with a period of half a year: (1) the solar heat input associated with the semiannual migration of the subsolar point between both hemispheres, which peaks at the equator and which is small in comparison with that in the annual component, and (2) the auroral heat input associated with the semiannual component in the occurrence of magnetic storms. An attempt is made to show that a number of apparent conflicts in the description and interpretation of the semiannual effect can be resolved by considering some of the dynamic properties of the thermosphere.
Volland, H.↗
Note on the 1972 Giacobinid meteor shower.
It is shown that the 1972 Giacobinid meteor shower was extremely weak with a peak activity of two to three visual meteors per hour. Only two meteor spectra were obtained from the 17 slitless spectrograph systems operated by the Langley Research Center. The largely unexpected, essentially null results of the 1972 Giacobinid meteor shower observations are indicative of the present limited understanding and predictability of cosmic dust storms.
Harvey, G. A.↗