Lecture Notes of the ICASE Workshop
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Brandt, A.↗
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A note on the R sub 0-parameter for discrete memoryless channels
An explicit class of discrete memoryless channels (q-ary erasure channels) is exhibited. Practical and explicit coded systems of rate R with R/R sub o as large as desired can be designed for this class.
Mceliece, R. J.↗
Data User's Note: Apollo seismological investigations
Seismological objectives and equipment used in the passive seismic, active seismic, lunar seismic profiling, and the lunar gravimeter experiments conducted during Apollo 11, 12, 14, 15, 16, and 17 missions are described. The various formats in which the data form these investigations can be obtained are listed an an index showing the NSSDC identification number is provided. Tables show manned lunar landing missions, lunar seismic network statistics, lunar impact coordinate statistics, detonation masses and times of EP's, the ALSEP (Apollo 14) operational history; compressed scale playout tape availability, LSPE coverage for one lunation, and experimenter interpreted events types.
Vostreys, R. W.↗
A note on sound radiation into a uniformly flowing fluid
Sound radiation generated by mechanical or vibratory source arrangements and, in some instances of planar or piston types, encompasses all magnitudes of the wavelength or frequency as well as disposition of the observation site. The comparative increase in average total radiated power from infinitesimally small or point sources of periodic strength, on passing from rest to steady rectilinear motion, depends only on Mach number in the noncompact case; and a formally analogous rise in output is linked, to the presence of a steady parallel flow past a rigid plane wall in which a compact circular piston executes normal oscillations. The perspective of effects connected with such a background is flow is widened by regard for an elongated or strip piston, which prototype permits a straightforward and general analysis.
Levine, H.↗
A note on solar elevation dependence of clear sky snow albedo
Recent attempts to match shortwave albedo of snow for clear skies using approximate spectral solar fluxes and solutions of the radiative transfer equation for snow were unsuccessful until a separate surface reflection term was introduced. A separate consideration of specular reflection from surface snow grains has been objected to as being ad hoc. Results based on a new parameterization of shortwave radiation are discussed. Compared to the previous radiation models, new model gives higher diffuse insolation and predicts higher albedos. The difference between observed and predicted albedos is substantially reduced without invoking surface reflection.
Choudhury, B. J.↗
Notes on the early-type components of W Cep, o Cet, CH Cyg, AR Mon, and BL Tel
Low resolution IUE spectra in both spectral regions are used to clarify the nature of the warmer components of several binary systems. The W Cep, the primary of which is a luminous K-type supergiant, shows an ultraviolet absorption spectrum of type B0 or B1; this system is heavily reddened. The hot companion of Mira (o Cet) is surprisingly faint in the short wavelength region, but it excites a rich emission spectrum from the surrounding gas. The ultraviolet active M7 giant CH Cyg is shown to be a binary with a hot companion. This system was also observed at high resolution and shows variable Fe II emission and well-separated circumstellar and interstellar absorptions within the broad Mg II emission profiles. The eclipsing binaries AR Mon and BL Tel are shown not to have hot companions.
Wing, R. F.↗
A note on sound radiation from distributed sources
The power output from a normally vibrating strip radiator is expressed in alternative general forms, one of these being chosen to refine and correct some particular estimates given by Heckl for different numerical ratios of strip width to wave length. An exact and explicit calculation is effected for sinusoidal velocity profiles when the strip width equals an integer number of half wave lengths.
Levine, H.↗
Note on reflection and transmission coefficients for converging-diverging ducts
Simple formulas for calculating acoustic reflection and transmission coefficients for converging-diverging ducts are derived; they extend the method of Cho and Ingard to arbitrary, slowly varying ducts. These formulas involve two parameters. The first is a function of duct shape and the second is the ratio of the duct radius downstream of the throat to that upstream of the throat to the upstream of the throat. An extension of the method to include mean flow is made for symmetric ducts.
Durbin, P. A.↗
Data Users Note: Lunar maps available from NSSDC
The types of maps available from the National Space Science Data Center/World Data Center A for Rockets and Satellites for the support of lunar and comparative planetology scientific investigations are identified and described. Information on other sources of maps useful to planetologists is included. The maps are listed according to increased map scale. Parameters given include the name, scale, date of edition, the four corner coordinates of each maps, and the NSSDC ID.
Vostreys, R. W.↗
A note on a Lagrangian formulation for motion about the collinear points
A Lagrangian formulation for the three-dimensional motion of a satellite in the vicinity of the collinear points of the circular-restricted problem is reconsidered. It is shown that the influence of the primaries can be expressed in the form of two third-body disturbing functions. By use of this approach, the equations for the Lagrangian and for the motion itself are readily developed into highly compact expressions. All orders of the non-linear developments are shown to be easily obtainable using well-known recursive relationships. The resulting forms for these equations are well suited for use in the initial phase of canonical or non-canonical investigations.
Richardson, D. L.↗
A note on antenna models in a warm isotropic plasma
The electron-transparent and electron-reflecting models of antennas in a warm isotropic plasma are reexamined. It is shown that a purely electrical treatment of both the models without an explicit use of the boundary condition on electron velocity yields the same results as those previously obtained through an electromechanical treatment. The essential difference between the two models is that for the electron-reflecting model, fields are nonzero only in the exterior region, while for the electron-transparent model, they are nonzero both in the exterior and interior regions of the antenna. This distinction helps in clarifying some misconceptions about these models of antennas in warm isotropic plasma.
Singh, N.↗
A note on the Allan Hills A77278 unequilibrated ordinary chondrite
Petrographic measures of disequilibrium in the ALHA 77278 chondrite indicate that this meteorite is more equilibrated than its exceptionally high volatile element contents suggest. Based on its metal compositions, this meteorite should be classified as an LL3 rather than an L3 chondrite.
Mcsween, H. Y., Jr.↗
Microfossil-like objects from the Archaean of Greenland - A cautionary note
Recent reports have described 'yeast-like microfossils' (Isuasphaera isua Pflug) in 3,800-million year old metaquartzites from the Isua supracrustal belt of south-west Greenland. A biogenic interpretation of these objects is inconsistent with the tectonic history of the Isua region, with the petrology of the metaquartzites, and with the morphology of the microstructures themselves. The putative microfossils are indistinguishable from limonite-stained fluid inclusions: microstructures which are demonstrably inorganic and post-depositional in origin. As such, it is contended that these objects should not be regarded as evidence of early Archaean life forms.
Bridgwater, D.↗
A note on the location of the stagnation point in the magnetosheath flow
While observational and theoretical investigations have clearly indicated that the shape of the magnetosphere is very nearly symmetric about the plane determined by the aberrated solar wind flow direction and the earth's magnetic dipole, many processes such as magnetic pulsations and geomagnetic activity which should be shape dependent do not exhibit symmetry about this plane. The present paper proposes a solution to this apparent paradox in terms of the shifting of the stagnation point in the magnetosheath flow. It is shown that the interplanetary magnetic field can act to shift the stagnation point on the order of 15 deg from the nose towards dawn during periods of low Alfven Mach number without an appreciable aberration of the magnetopause, accounting for the observations of pulsation demarcation and magnetic reconnection.
Russell, C. T.↗
Additional measurements of the high-latitude sunspot rotation rate /Research note/
Sunspot rotation rate measurements at high sunspot latitudes are reported for the period 1966-68, based on ten spots at latitudes greater than about 28 deg from H-alpha patrol records for this period. A sidereal rotation rate of 13.70 + or - 0.07 deg/day was found on the average, at 31.05 + or - 0.01 deg. Taken together, the full set of measurements in this latitude regime yield a rotation rate that is in excellent agreement with the result derived by Newton and Nunn (1951) from recurrent spots at lower latitudes throughout the six cycles from 1878 to 1944.
Landman, D. A.↗
Notes on the P/Halley nucleus
Indirect evidence and theory concerning the nucleus of P/Halley are summarized. Reasonable estimates place its diameter in the range 2.5 to 4.0 km, but the true value may well lie outside these bounds. The observed activity in its inner coma indicates that the nucleus is spotty and contains small activity areas as do other similar comets. Whether these active areas will show as dark or light regions on the nucleus is not known. Jets of dust will probably obscure parts of the nucleus when imaged by a nearby spacecraft.
Whipple, F. L.↗
Technical communication: Notes toward defining discipline
In the field of technical communication, definitions posited in virtually any major text violate every major rule of definitions. The most popular method for defining the field is to state that technical writing is any writing that supports technology or technological activities. There is a need for a nice yardstick for measuring what "technology" is. Some ways in which the field can be defined in a tightly structured empirical way and some implications of technical communication for a humanistic education in a technological age are suggested.
Rubens, P. M.↗
A note on deep space optical communication link parameters
Topical communication in the context of a deep space communication link. Communication link analysis at the optical frequencies differs significantly from that at microwave frequencies such as the traditional S and X-bands used in deep space applications, due to the different technology of transmitter, antenna, modulators, and receivers. In addition, the important role of quantum noise in limiting system performance is quite different than that of thermal noise. The optical link design is put in a design control table format similar to a microwave telecom link design. Key considerations unique to the optical link are discussed.
Dolinar, S. J.↗