Density Of Use Research Articles

Reproducible fabrication of PuO 2 fuel

PuO 2 fuel pellets with stable microstructures at 80 to 90% theoretical density for use at temperatures up to 1400°C can be fabricated by a granulation and hot pressing process. Three interdependent factors which must be controlled for reproducible fabrication of microstructure and density to ±0.5% are: particle size and morphology of plutonium oxalate precipitate, particle size of calcined PuO 2 powder after ball milling, and temperature at which granules made from milled powder are presintered prior to hot pressing. Relationships are presented between each of these factors and their effect on the density and integrity of the fuel form.

Satellite Bearing Torque Noise

Many spin-stabilized spacecraft use precision ball bearings to support and to align an antenna or instrument platform relative to the rotor. The pointing accuray of the instrument platform is affected by the dynamic fluctuations in running torque or torque noise of the bearings. Although many previous investigations have been concerned with average (or dc) torque, there is a lack of information on the spectral distribution of the torque noise of lightly loaded, large-diameter bearings at slow speeds. This paper summarizes experiments performed on seven pairs of bearings of two bore sizes. Limited measurements of bearings profilometry were made. A special fixture was used to measure torque noise over a range of preload, rotational speed, and temperature. The bearing torque noise was processed by a computer to obtain torque spectral density and rms. On the basis of this experimental data, an ad hoc model was developed to estimate torque spectral density for use in control system preliminary design and feasi...

GAMMA PROBE DRY BULK DENSITIES

The gamma density probe is a useful instrument for measuring water content in small volumes of soil. Essentially, the gamma probe measures the density of the soil and water between a source and a detector. To transpose the gamma densities into water content, the dry bulk density of the soil is needed. A nondestructive method for estimating dry bulk densities for use with the gamma probe is proposed. The procedure is based on the assumption that water content values in a field dry condition were more stable than the dry bulk density values and could be transferred from one point to another. The procedure was successfully used on three areas in Reynolds Creek Experimental Watershed in Southwest Idaho. /Author/

Densities of use and absence of obsolescence in physics journals at M.I.T.

Densities of use and absence of obsolescence in physics journals at M.I.T.

Densities of use, and absence of obsolescence, in physics journals at M I T

AbstractChen's data for the raw frequency of use of 138 physics journals in the science library at M I T are re‐examined and converted to densities of use‐per‐metre of shelf. Other units of size for obtaining densities, and their measurement, are discussed. There is no evidence for synchronous obsolescence in the 1955 to 1968 volumes of these journals: instead there is some statistically significant evidence of greater density of use with greater age. Similar evidence elsewhere is cited. The ranking order for heaviness of use is also radically altered by converting raw frequencies to densities of use.It is suggested that, for comparing the relative values of different journals, or age groups, in library use or citation studies, analyses of raw frequencies are valueless, and indeed potentially dangerously misleading, until they are converted to allow for the numbers of available items in each group examined.

Linear Restoration of Incoherently Radiating Objects

Light from an incoherently radiating object and background light are focused onto a photosensitive mosaic, the currents from whose elements constitute the data on which is based a least-squares linear estimate of the radiance at points in the object. By comparison of the mean-square error with that given by Wiener filtering theory, the equivalent noise spectral density for use in the latter is shown to consist of a shot-noise term and a term due to the random fluctuations of the incoherent light; the former predominates under most circumstances. Turbulent distortion of the image after passage of the rays through a random-phase screen is also treated from this standpoint.

CORRELATION OF ROCK DENSITY DETERMINATIONS FOR GRAVITY SURVEY INTERPRETATION*

ABSTRACTThe results of field and laboratory methods of density determination on a series of Coal Measure, Permian and Triassic rooks are presented and the different methods compared. It is concluded that the most satisfactory method is that of measuring the vertical change of gravity in a mine shaft. Nettleton's method is unsatisfactory to us, due to weathering of the rocks (particularly Magnesian Limestone) and possible effects from drift. Laboratory measurements are of variable value depending on the lithology and source of the samples.A method adopted to solve the problem of finding the true densities for use in a local gravity survey in N.E. England is given.

Some Economics of Airports

So much has been written regarding the location and the engineering design of airports that the writer has chosen rather to discuss some of the economic factors relating to the growth in size and in density of use of existing ports. This paper also deals largely with ports intended for transport planes. Until recently, the number of airports had reached and declined from a saturation point. Under the stimulus of war there is now (1941) a renewed growth, and a higher saturation value, although at present there is no reliable indicator to serve as a guide. For example, many state planning bodies are compiling lists of airports to be built progressively as the demand requires, and these will be correlated into a nation-wide plan; but the problem facing the present-day designer is primarily one of improvement and enlargement of present facilities.