10,218 research outputs found
THE USE OF AN IONIZATION GAGE AS A QUANTITATIVE ANALYZER FOR BIGASEOUS MIXTURES
Helium & air - ionization gauge for determining percentage composition of gaseous mixture
Gas analyzer for bi-gaseous mixtures Patent
Gas analyzer for bi-gaseous mixtures suitable for use in test facilitie
Implications of microwave spectroscopy for the water-vapor content of the Venus atmosphere
Brightness temperature spectra of Venus computed to determine amount of water vapor in lower atmospher
Mobility of Dislocations in Aluminum
The velocities of individual dislocations of edge and mixed types in pure aluminum single crystals were determined as a function of appliedâresolved shear stress and temperature. The dislocation velocities were determined from measurements of the displacements of individual dislocations produced by stress pulses of known duration. The BergâBarrett xâray technique was employed to observe the dislocations, and stress pulses of 15 to 108 ÎŒsec duration were applied by propagating torsional waves along the axes of [111]âoriented cylindrical crystals. Resolved shear stresses up to 16Ă10^6 dynesâcm^2 were applied at temperatures ranging from â150° to +70°C, and dislocation velocities were found to vary from 10 to 2800 cmâsec over these ranges of stress and temperature. The experimental conditions were such that the dislocation velocities were not significantly influenced by impurities, dislocation curvature, dislocationâdislocation interactions, or longârange internal stress fields in the crystals. The velocity of dislocations is found to be linearly proportional to the appliedâresolved shear stress, and to decrease with increasing temperature. Qualitative comparison of these results with existing theories leads to the conclusion that the mobility of individual dislocations in pure aluminum is governed by dislocationâphonon interactions. The phononâviscosity theory of dislocation mobility can be brought into agreement with the experimental results by reasonable choices of the values of certain constants appearing in the theory
Mobility of Edge Dislocations in the BasalâSlip System of Zinc
This paper presents the results of measurements of the velocities of ă1210ă (0001) edge dislocations in zinc as a function of applied shear stress. All tests were conducted at room temperature on 99.999% pure zinc monocrystals. Dislocations were revealed by means of the BergâBarrett xâray technique. Stress pulses of microsecond duration were applied to the test specimens by means of a torsion testing machine. Applied resolved shear stresses ranged from 0 to 17.2Ă10^6 dynâcm^2 and measured dislocation velocities ranged from 40â700 cmâsec. The results of this study indicate that the velocity of edge dislocations in the basal slip system of zinc is linearly proportional to the applied resolved shear stress. These results are analyzed in terms of the phonon drag theory. Agreement between this theory and the results reported here is quite good
Recycling Roman glass to glaze Parthian pottery
Alkaline glazes were first used on clay-based ceramics in Mesopotamia around 1500 B.C., at the same time as the appearance of glass vessels. The Roman Empire used lead-based glazes, with alkaline natron glass being used only to produce objects of glass. Chemical analysis has had some success determining compositional groups for Roman/Byzantine/early Islamic glasses because of the discovery of major production sites. Parthian and Sasanian glass and glazed wares, however, have been found only in consumption assemblages, which have failed to inform on how they were made. Here we reanalyse compositional data for Parthian and Sasanian glazes and present new analyses for Parthian glazed pottery excavated at the early third century A.D. Roman military outpost of Ain Sinu in northern Iraq. We show that some Parthian glazes are from a different tradition to typical Mesopotamian glazes and have compositions similar to Roman glass. We propose that Roman glass was recycled by Parthian potters, thereby suggesting that as yet undiscovered Mesopotamian glass production centres ordinarily supplied glass for indigenous glazed pottery. Furthermore, if recycling glass to make glazed pottery was extended to indigenous glassware, this may provide an explanation for the paucity of Parthian and Sasanian glass in the archaeological record
The Digital Flynn Effect: Complexity of Posts on Social Media Increases over Time
Parents and teachers often express concern about the extensive use of social
media by youngsters. Some of them see emoticons, undecipherable initialisms and
loose grammar typical for social media as evidence of language degradation. In
this paper, we use a simple measure of text complexity to investigate how the
complexity of public posts on a popular social networking site changes over
time. We analyze a unique dataset that contains texts posted by 942, 336 users
from a large European city across nine years. We show that the chosen
complexity measure is correlated with the academic performance of users: users
from high-performing schools produce more complex texts than users from
low-performing schools. We also find that complexity of posts increases with
age. Finally, we demonstrate that overall language complexity of posts on the
social networking site is constantly increasing. We call this phenomenon the
digital Flynn effect. Our results may suggest that the worries about language
degradation are not warranted
A comparison between pulsed and CW laser annealing for solar cell applications
The application of laser processing in solar cell fabrication is considered. Specific emphasis is placed on a process developed for the fabrication of a 16.6% silicon solar cell using pulsed laser processing. Results are presented which compare pulsed laser annealing with CW laser annealing in solar cell fabrication
Rare isotope studies involving catalytic oxidation of CO over platinum-tin oxide
Results of studies utilizing normal and rare oxygen isotopes in the catalytic oxidation of carbon monoxide over a platinum-tin oxide catalyst substrate are presented. Chemisorption of labeled carbon monoxide on the catalyst followed by thermal desorption yielded a carbon dioxide product with an oxygen-18 composition consistent with the formation of a carbonate-like intermediate in the chemisorption process. The efficacy of a method developed for the oxygen-18 labeling of the platinum-tin oxide catalyst surface for use in closed cycle pulsed care isotope carbon dioxide lasers is demonstrated for the equivalent of 10 to the 6th power pulses at 10 pulses per second
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