3,035 research outputs found
Development of material specifications and qualifications of polymeric materials for the JPL Spacecraft Materials Guidebook Monthly technical progress report no. 11, 10 Apr. - 10 May 1965
Outgassing characteristics of liquid and paste silicones and effects of postcuring procedure
Development of material specifications and qualifications of polymeric materials for the jpl spacecraft materials guidebook. 1- epoxide adhesives special report no. 1
Outgassing characteristics of nine epoxide adhesives, and thermal vacuum performance for adhesives teste
Development of material specifications and qualifications of polymeric materials for the jpl spacecraft materials guidebook. ii- rtv silicone adhesives and potting compounds special report no. 2
Silicone rubber adhesives and potting compounds - polymeric materials for spacecraf
Steady States of a Nonequilibrium Lattice Gas
We present a Monte Carlo study of a lattice gas driven out of equilibrium by
a local hopping bias. Sites can be empty or occupied by one of two types of
particles, which are distinguished by their response to the hopping bias. All
particles interact via excluded volume and a nearest-neighbor attractive force.
The main result is a phase diagram with three phases: a homogeneous phase, and
two distinct ordered phases. Continuous boundaries separate the homogeneous
phase from the ordered phases, and a first-order line separates the two ordered
phases. The three lines merge in a nonequilibrium bicritical point.Comment: 14 pages, 24 figure
Compaction and Chemical Grouting for Drain Tunnels in Phoenix
Ground runs during ml.m.ng of the Papago Freeway Drain Tunnels posed significant potential risk to utilities, street pavement, and buildings located above and adjacent to one of the three tunnel alignments. Ground response to the larger ground runs resulted in open chimneys and settlement of the ground surface of up to several feet. Modifications to the tunneling machine included addition of poling plates and breasting boards. Further modification to the tunneling method included use of compaction grouting in conjunction with mining for the entire length of one tunnel alignment, and use of chemical grouting to prestabilize the ground surrounding the tunnel opening in areas of high risk utilities and in areas where subsurface conditions suggested that running ground would be encountered during mining. This paper presents a summary of the ground behavior with and without the compaction and chemical grouting and describes the grouting methods
Modified Petri net model sensitivity to workload manipulations
Modified Petri Nets (MPNs) are investigated as a workload modeling tool. The results of an exploratory study of the sensitivity of MPNs to work load manipulations in a dual task are described. Petri nets have been used to represent systems with asynchronous, concurrent and parallel activities (Peterson, 1981). These characteristics led some researchers to suggest the use of Petri nets in workload modeling where concurrent and parallel activities are common. Petri nets are represented by places and transitions. In the workload application, places represent operator activities and transitions represent events. MPNs have been used to formally represent task events and activities of a human operator in a man-machine system. Some descriptive applications demonstrate the usefulness of MPNs in the formal representation of systems. It is the general hypothesis herein that in addition to descriptive applications, MPNs may be useful for workload estimation and prediction. The results are reported of the first of a series of experiments designed to develop and test a MPN system of workload estimation and prediction. This first experiment is a screening test of MPN model general sensitivity to changes in workload. Positive results from this experiment will justify the more complicated analyses and techniques necessary for developing a workload prediction system
What Is Evolution? A Response to Bamforth
Douglas Bamforth\u27s recent paper in American Antiquity, Evidence and Metaphor in Evolutionary Archaeology, charges that Darwinism has little to offer archaeology except in a metaphorical sense. Specifically, Bamforth claims that arguments that allegedly link evolutionary processes to the archaeological record are unsustainable. Given Bamforth\u27s narrow view of evolution: that it must be defined strictly in terms of changes in gene frequency: he is correct. But no biologist or paleontologist would agree with Bamforth\u27s claim that evolution is a process that must be viewed fundamentally at the microlevel. Evolutionary archaeology has argued that materials in the archaeological record are phenotypic in the same way that hard parts of organisms are. Thus changes in the frequencies of archaeological variants can be used to monitor the effects of selection and drift on the makers and users of those materials. Bamforth views this extension of the human phenotype as metaphorical because to him artifacts are not somatic features, meaning their production and use are not entirely controlled by genetic transmission. He misses the critical point that in terms of evolution, culture is as significant a transmission system as genes are. There is nothing metaphorical about viewing cultural transmission from a Darwinian point of view
Mapping the CMB II: the second flight of the QMAP experiment
We report the results from the second flight of QMAP, an experiment to map
the cosmic microwave background near the North Celestial Pole. We present maps
of the sky at 31 and 42 GHz as well as a measurement of the angular power
spectrum covering the l-range 40-200. Anisotropy is detected at about 20 sigma
and is in agreement with previous results at these angular scales. We also
report details of the data reduction and analysis techniques which were used
for both flights of QMAP.Comment: 4 pages, with 5 figures included. Submitted to ApJL. Window functions
and color figures are available at
http://pupgg.princeton.edu/~cmb/welcome.htm
Generalized monotonic functional mixed models with application to modelling normal tissue complications
Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/73586/1/j.1467-9876.2007.00606.x.pd
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