Surface tension and contact angles: Molecular origins and associated microstructure

Gradient theory converts the molecular theory of inhomogeneous fluid into nonlinear boundary value problems for density and stress distributions in fluid interfaces, contact line regions, nuclei and microdroplets, and other fluid microstructures. The relationship between the basic patterns of fluid phase behavior and the occurrence and stability of fluid microstructures was clearly established by the theory. All the inputs of the theory have molecular expressions which are computable from simple models. On another level, the theory becomes a phenomenological framework in which the equation of state of homogeneous fluid and sets of influence parameters of inhomogeneous fluids are the inputs and the structures, stress tensions and contact angles of menisci are the outputs. These outputs, which find applications in the science and technology of drops and bubbles, are discussed

An evaluation of auroral all-sky camera observations

From photometric, all-sky camera, and visual observations of a moderate auroral display, it is found that the all-sky camera compares favorably with the visual observer in detecting and recording auroral forms. The visual observer can make instantaneous observations and so can detect rapid changes and auroral forms lasting only a few seconds, whereas the poorer time resolution of the all-sky camera prevents it from recording very short-lived phenonema. However, the ability of the all-sky camera to accurately record the shape and intensity of the majority of auroral forms allows it to yield more precise and complete information about these aspects of auroral morphology than is normally obtained through visual observation.Ye

Improved space radiation shielding methods

The computing software that was used to perform the charged particle radiation transport analysis and shielding design for the Mariner Jupiter/Saturn 1977 spacecraft is described. Electron fluences, energy spectra and dose rates obtained with this software are presented and compared with independent computer calculations

Law of corresponding state for the transport properties of molten salts

Corresponding state theory for transport properties of ionic fused alkali salt

Pollution reduction technology program for small jet aircraft engines: Class T1

Small jet aircraft engines (EPA class T1, turbojet and turbofan engines of less than 35.6 kN thrust) were evaluated with the objective of attaining emissions reduction consistent with performance constraints. Configurations employing the technological advances were screened and developed through full scale rig testing. The most promising approaches in full-scale engine testing were evaluated

ASCA observations of massive medium-distant clusters of galaxies. II

We have selected seven medium-distant clusters of galaxies (z ~ 0.1 - 0.3) for multi-wavelength observations with the goal of investigating their dynamical state. Following Paper I (Pierre et al. 1999) which reported the ASCA results about two of them, we present here the analysis of the ASCA observations of the other five clusters; RXJ1023.8-2715 (A3444), RXJ1031.6-2607, RXJ1050.5-0236 (A1111), RXJ1203.2-2131(A1451), and RXJ1314.5-2517. Except for RXJ1031.6, whose X-ray emission turned out to be dominated by an AGN, the ASCA spectra are well fitted by a one-temperature thin thermal plasma model. We compare the temperature-luminosity relation of our clusters with that of nearby ones (z<0.1). Two clusters, RXJ1050.5 and RXJ1023.8, show larger luminosities than the bulk of clusters at similar temperatures, which suggests the presence of a cooling flow. The temperature vs. iron-abundance relationship of our sample is consistent with that of nearby clusters.Comment: 9 pages, 20 figures, A&AS in pres

The Philosophy of Science

A few months ago I sat at a banquet in a room of mirrors. The group of guests communicated with one another by spoken words. But as I sat and looked down the corridor of reflected images of ourselves, I could not help but feel that a vision of the great past of the human race was presented to my eye. As far as one could see, a vast assemblage of human forms was visible and I felt that in this little instant of the present time we were accompanied by the shadows of all those who had lived before us. There in a distant image I caught a glimpse of the lofty figures of the Athenian school, Aristotle walking among the olive trees; Hippocrates, probing into the cause of human ills from which he formulated an oath that in later times was to be adopted as one of the most idealistic principles of the race. A little nearer we view the scholars of the great University of Alexandria. There is Euclid reflecting upon the theorems in his immortal Elements. We see also the image of Aristarchus, measuring the distance to the sun and moon, and Eratosthenes, centuries ahead of his times, proving that the earth is spherical and measuring its diameter. And there is Archimedes laying the foundations of mechanics, and Hero with his steam engine, and Ptolemy reflecting upon the mystery of the planets. A little nearer our own times we see the mystic figure of Galileo, defying the prejudice of his age and proving that the earth is but a moving atom in a universe of unimaginable magnitude. And there is Newton penning the immortal passages of his Principia. And there also are Faraday and Maxwell, Wallace and Darwin, Koch and Pasteur, Lamarck and Werner, and all the other immortals who by their careful studies and brilliant generalizations were to found that thing which we have called by the simple name of Science

ERBS fuel addendum: Pollution reduction technology program small jet aircraft engines, phase 3

A Model TFE731-2 engine with a low emission, variable geometry combustion system was tested to compare the effects of operating the engine on Commercial Jet-A aviation turbine fuel and experimental referee broad specification (ERBS) fuels. Low power emission levels were essentially identical while the high power NOx emission indexes were approximately 15% lower with the EBRS fuel. The exhaust smoke number was approximately 50% higher with ERBS at the takeoff thrust setting; however, both values were still below the EPA limit of 40 for the Model TFE731 engine. Primary zone liner wall temperature ran an average of 25 K higher with ERBS fuel than with Jet-A. The possible adoption of broadened proprties fuels for gas turbine applications is suggested

Pollution reduction technology program small jet aircraft engines, phase 3

A series of Model TFE731-2 engine tests were conducted with the Concept 2 variable geometry airblast fuel injector combustion system installed. The engine was tested to: (1) establish the emission levels over the selected points which comprise the Environmental Protection Agency Landing-Takeoff Cycle; (2) determine engine performance with the combustion system; and (3) evaulate the engine acceleration/deceleration characteristics. The hydrocarbon (HC), carbon monoxide (CO), and smoke goals were met. Oxides of nitrogen (NOx) were above the goal for the same configuration that met the other pollutant goals. The engine and combustor performance, as well as acceleration/deceleration characteristics, were acceptable. The Concept 3 staged combustor system was refined from earlier phase development and subjected to further rig refinement testing. The concept met all of the emissions goals

Pollution Reduction Technology Program for Small Jet Aircraft Engines, Phase 2

A series of iterative combustor pressure rig tests were conducted on two combustor concepts applied to the AiResearch TFE731-2 turbofan engine combustion system for the purpose of optimizing combustor performance and operating characteristics consistant with low emissions. The two concepts were an axial air-assisted airblast fuel injection configuration with variable-geometry air swirlers and a staged premix/prevaporization configuration. The iterative rig testing and modification sequence on both concepts was intended to provide operational compatibility with the engine and determine one concept for further evaluation in a TFE731-2 engine