25,639 research outputs found
Effect of strain rate and load cycling on the tensile behavior and air permeability of a coated fabric
Effect of strain rate and load cycling on tensile behavior and air permeability of coated fabric for inflatable decelerator syste
Scientific Report Number 2
I. INTRODUCTION
The earlier orbits and ephemerides for the Soviet satellites were not sufficiently
accurate to be very useful in making observations in Alaska. Extrapolations
from our own observations gave better predictions. This merely pointed out the fact
that rough observations of meridian transits at high latitudes will give better values
of the inclination of the orbit than precision observations at low latitudes. Hence,
it was decided to observe visually the meridian transits estimating the altitude by
noting the position with respect to the stars or using crude alidade measurements.
The times of the earlier observations were observed on a watch or clock and the clock
correction obtained from WWV. Later the times were determined with the aid of stop
watches, taking time intervals from WWV signals.
This rather meager program of optical observations of the Soviet satellites was
undertaken to give supplementary data for use of the radio observations, and particularly
to assist in the prediction of position of the satellite so that the 61-foot
radar of Stanford Research Institute could be set accurately enough to observe it
(the beam width at the half-power points is about 3°).
This report contains primarily the visual observations made at the Geophysical
Institute by various members of the staff, and a series of observations by Olaf
Halverson at Nome, Alaska. In addition there is a short discussion of the geometry
of the trajectory, the illumination of a circumpolar satellite, and a note on the
evaluation of Brouwer's moment factors.Air Force Contract No. AF 30(635)-2887
Project No. 5535 - Task 45774
Rome Air Development Center
Griffiss Air Force Base
Rome, New YorkI. Introduction -- II. Visual Observations -- III. Geometry of the Trajectory -- IV. Seasonal Illumination of a Circumpolar Earth Satellite at its
Extreme Latitude Orbit-Point. -- V. Tentative Evaluation of Brouwer's Moment Factors.Ye
Attachment methods for advanced spacecraft thermal control materials - An annotated bibliography, phase 1 Summary report supplement
Annotated bibliography on attachment methods for advanced spacecraft thermal control material
Syndromic and Point-of-Care Molecular Testing
This article is made available for unrestricted research re-use and secondary analysis in any form or by any means with acknowledgement of the original source. These permissions are granted for the duration of the World Health Organization (WHO) declaration of COVID-19 as a global pandemic
Experiments with a Model Water Tunnel
This report describes a model water tunnel built in 1928 by the NACA to investigate the possibility of using water tunnels for aerodynamic investigations at large scales. The model tunnel is similar to an open-throat wind tunnel, but uses water for the working fluid
The Case for UHP Conditions in the Cuaba Terrane, Río San Juan Metamorphic Complex, Dominican Republic
From the Cuaba terrane in northern Dominican Republic. Ultrahigh pressure (UHP) conditions are indicated for the Cuaba terrane on the basis of phase relationships in garnet-bearing ultramafic rock. Dikes and orthocumulate textures indicate a magmatic origin. Mineral assemblages define a line of descent controlled by fractional crystallization. The original estimate of the magmatic conditions (P>3.4GPa, T>1550°C) was inferred previously from available high-P melting experiments in the CMAS system and high-P experimental determination of the sapphirine-out reaction in the MAS system. Revised estimates of magmatic conditions (P>3.2GPa, T>1500°C) take into account the influence of other components, especially Fe. We propose an origin in the mantle-wedge above a subduction zone. The rock was delivered to the subduction zone by forced convection in the mantle wedge (corner-flow), coupled with erosion of the hanging wall. Thermobarometry indicates >850°C and >3.4GPa when the ultramafic rock was incorporated into eclogite (deep-subducted oceanic crust). Evidence for UHP conditions in the retrograded eclogite is not obvious. Two types of symplectic intergrowths, plagioclase + clinopyroxene (Sym-I) and plagioclase + epidote (Sym-II), are interpreted as the products of the decomposition of two types of omphacite, Omp-I and Omp-II. Theoretically, Omp-II formed as the result of a retrograde reaction of the form, Omp-II + coesite = Omp-I + kyanite + /- garnet, according to which the maximum pressure for Omp-II is between ~2.8GPa (~850°C) and ~4.2GPa (~950°C), consistent with subsolidus conditions for the garnet-bearing ultramafic rocks. For eclogite, the highest-pressure mineral assemblage would have been Omp-I + kyanite + garnet + coesite
Searches for Gravitational Waves from Binary Neutron Stars: A Review
A new generation of observatories is looking for gravitational waves. These
waves, emitted by highly relativistic systems, will open a new window for ob-
servation of the cosmos when they are detected. Among the most promising
sources of gravitational waves for these observatories are compact binaries in
the final min- utes before coalescence. In this article, we review in brief
interferometric searches for gravitational waves emitted by neutron star
binaries, including the theory, instru- mentation and methods. No detections
have been made to date. However, the best direct observational limits on
coalescence rates have been set, and instrumentation and analysis methods
continue to be refined toward the ultimate goal of defining the new field of
gravitational wave astronomy.Comment: 30 pages, 5 Figures, to appear in "Short-Period Binary Stars:
Observations, Analyses, and Results", Ed.s Eugene F. Milone, Denis A. Leahy,
David W. Hobil
Optimal coding of a random stimulus by a population of parallel neuron models
Copyright © 2007 SPIE - The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only. Copyright 2007 Society of Photo-Optical Instrumentation Engineers. This paper was published in Noise and Fluctuations in Biological, Biophysical, and Biomedical Systems, edited by Sergey M. Bezrukov, Proc. of SPIE Vol. 6602, 66020R and is made available as an electronic reprint with permission of SPIE. One print or electronic copy may be made for personal use only. Systematic or multiple reproduction, distribution to multiple locations via electronic or other means, duplication of any material in this paper for a fee or for commercial purposes, or modification of the content of the paper are prohibited.We examine the question of how a population of independently noisy sensory neurons should be configured to optimize the encoding of a random stimulus into sequences of neural action potentials. For the case where firing rates are the same in all neurons, we consider the problem of optimizing the noise distribution for a known stimulus distribution, and the converse problem of optimizing the stimulus for a given noise distribution. This work is related to suprathreshold stochastic resonance (SSR). It is shown that, for a large number of neurons, the SSR model is equivalent to a single rate-coding neuron with multiplicative output noise.Mark D. McDonnell, Nigel G. Stocks and Derek Abbot
Saturation Spectroscopy of Iodine in Hollow-core Optical Fibre
We present high-resolution spectroscopy of Iodine vapour that is loaded and
trapped within the core of a hollow-core photonic crystal fibre (HC-PCF). We
compare the observed spectroscopic features to those seen in a conventional
iodine cell and show that the saturation characteristics differ significantly.
Despite the confined geometry it was still possible to obtain sub-Doppler
features with a spectral width of ~6 MHz with very high contrast. We provide a
simple theory which closely reproduces all the key observations of the
experiment.Comment: 12 pages, 7 figure
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