572 research outputs found
State of gas exchange in recumbent and orthostatic positions and under physical load in healthy persons of varying age, sex and body build
Age effect on gas exchange was studied in the recumbent and orthostatic positions and under physical load. In the case of the older age group and for normal as compared with hypersthenic persons, oxygen consumption during rest and during moderate physical overload diminishes. When the vertical position is assumed oxygen consumption in persons of various age groups is distinctly increased, particularly in the elderly group. There is a reduction in the amount of oxygen consumption, oxygen pulse, recovery coefficient, and work efficiency under moderate overload. In persons over 50, physical labor induces a large oxygen requirement and a sharp rise in the level of lactic acid and the blood's lactate/pyruvate ratio. No distinct difference was noted in the amount of oxygen consumed during rest and during physical overload in men and women of the same physical development and age
Analysis of structure-phase states in-a-bulk hardened and a head-hardened rails
A layer-by-layer analysis along the central axis and over the fillet of rails for low-temperature service, rails with enhanced wear resistance and contact fatigue resistance, and for senior-grade rails, bulk oil hardened and DT 350 rails head-hardened under different conditions has been carried out by modern material science methods. Quantitative variables have been established and a comparison of structure-phase states, defective substructure and internal stress fields has been made
Microstructure and crystallographic texture of silicon iron modified by torsion under quasihydrostatic pressure
The electron backscatter diffraction, X-ray diffraction analysis, electromotive force instantaneous measurement, microhardness and coercive force measurement techniques are used to explore the development of the microstructure, crystallographic texture and physico-mechanical properties of silicon iron (Fe-3% Si) alloy under quasi-hydrostatic pressure in a Bridgman anvil. It is found that the alloy deformation is accompanied by its significant hardenin
Virtual Shaping on NACA 0015 by Means of a High Momentum Coefficient Synthetic Jet
Results concerning flow control on a NACA 0015 airfoil using high power synthetic jets are presented for low incidences and for Reynolds numbers ranging from 132000 to 425000. The forcing was operated through a spanwise slit positioned near the leading edge at x/c=1.25% or at x/c=10% on the upper surface. Static pressure distribution measurements around the airfoil, wake surveys and smoke flow visualizations were performed. Pressure distributions were significantly modified around the injection location, showing an area of intense suction which increased the lift and strongly affected the drag. Flow visualizations highlighted that the intense suction was due to a virtual shaping effect caused by the formation of a recirculation bubble capable of displacing the streamlines. Low momentum deficits in the wake velocity distributions and, in certain conditions, jet-like flow was observed for the forced cases. Finally, a scaling law relating the bubble size to the forcing intensity is propose
Deformation behavior of high-mn TWIP steels processed by warm-to-hot working
The deformation behavior of 18%Mn TWIP steels (upon tensile tests) subjected to warm-to-hot rolling was analyzed in terms of Ludwigson-type relationship, i.e., a = K\ e”1 + exp(K - ”2 e). Parameters of Ki and ” depend on material and processing conditions and can be expressed by unique functions of inverse temperatur
The Sunyaev-Zel'dovich Infrared Experiment: A Millimeter-wave Receiver for Cluster Cosmology
Measurements of the Sunyaev-Zel'dovich (S-Z) effect towards distant clusters
of galaxies can be used to determine the Hubble constant and the radial
component of cluster peculiar velocities. Determination of the cluster peculiar
velocity requires the separation of the two components of the S-Z effect, which
are due to the thermal and bulk velocities of the intracluster plasma. The two
components can be separated practically only at millimeter (mm) wavelengths.
Measurements of the S-Z effect at mm wavelengths are subject to minimal
astrophysical confusion and, therefore, provide an important test of results
obtained at longer wavelengths. We describe the instrument used to make the
first significant detections of the S-Z effect at millimeter wavelengths. This
instrument employs new filter, detector, and readout technologies to produce
sensitive measurements of differential sky brightness stable on long time
scales. These advances allow drift scan observations which achieve high
sensitivity while minimizing common sources of systematic error.Comment: 19 pages, 15 postscript figures, LaTeX(aaspptwo.sty), ApJ(in press
Optimal measurement of visual motion across spatial and temporal scales
Sensory systems use limited resources to mediate the perception of a great
variety of objects and events. Here a normative framework is presented for
exploring how the problem of efficient allocation of resources can be solved in
visual perception. Starting with a basic property of every measurement,
captured by Gabor's uncertainty relation about the location and frequency
content of signals, prescriptions are developed for optimal allocation of
sensors for reliable perception of visual motion. This study reveals that a
large-scale characteristic of human vision (the spatiotemporal contrast
sensitivity function) is similar to the optimal prescription, and it suggests
that some previously puzzling phenomena of visual sensitivity, adaptation, and
perceptual organization have simple principled explanations.Comment: 28 pages, 10 figures, 2 appendices; in press in Favorskaya MN and
Jain LC (Eds), Computer Vision in Advanced Control Systems using Conventional
and Intelligent Paradigms, Intelligent Systems Reference Library,
Springer-Verlag, Berli
Measurement of the Hubble Constant from X-ray and 2.1 mm Observations of Abell 2163
We report 2.1 mm observations of the Sunyaev-Zel'dovich (S-Z) effect; these
observations confirm our previous detection of a decrement in the Cosmic
Microwave Background intensity towards the cluster Abell 2163. The S-Z data are
analyzed using the relativistically correct expression for the Comptonization.
We begin by assuming the intracluster (IC) gas to be isothermal at the emission
weighted average temperature determined by a combined analysis of the ASCA and
GINGA X-ray satellite observations. Combining the X-ray and S-Z measurements,
we determine the Hubble constant to be H_0(q_0=0.5)= 60 +40/-23 km/s/Mpc, where
the uncertainty is dominated by the systematic difference in the ASCA and GINGA
determined IC gas temperatures. ASCA observations suggest the presence of a
significant thermal gradient in the IC gas. We determine as a function of
the assumed IC gas thermal structure. Using the ASCA determined thermal
structure and keeping the emission weighted average temperature the same as in
the isothermal case, we find H_0(q_0=0.5)= 78 +54/-28 km/s/Mpc. Including
additional uncertainties due to cluster asphericity, peculiar velocity, IC gas
clumping, and astrophysical confusion, we find H_0(q_0=0.5)= 78 +60/-40
km/s/Mpc.Comment: 24 pages, 10 postscript figures, LaTeX(aaspptwo.sty), ApJ(in press
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