36,232 research outputs found
Study of Scalar Mesons and Related Radiative Decays
After a brief review of the puzzling light scalar meson sector of QCD, a
brief summary will be given of a paper concerning radiative decays involving
the light scalars. There, a simple vector meson dominance model is constructed
in an initial attempt to relate a large number of the radiative decays
involving a putative scalar nonet to each other. As an application it is
illustrated why mixing is not expected to greatly alter the
production ratio for radiative decays.Comment: 9 pages, 3 figures, Talk presented at SUNYIT (Utica/NY) conference on
High Energy Physics, June 6, 200
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
Development of material specifications and qualifications of polymeric materials for the jpl spacecraft materials guide book. iii- polyfluorocarbon films special report no. 3
Outgassing studies of polyfluorocarbon films - investigation of polymers as spacecraft construction material
Possible Observational Criteria for Distinguishing Brown Dwarfs from Planets
The difference in formation process between binary stars and planetary
systems is reflected in their composition as well as their orbital
architecture, particularly orbital eccentricity as a function of orbital
period. It is suggested here that this difference can be used as an
observational criterion to distinguish between brown dwarfs and planets.
Application of the orbital criterion suggests that with three possible
exceptions, all of the recently-discovered substellar companions discovered to
date may be brown dwarfs and not planets. These criterion may be used as a
guide for interpretation of the nature of sub-stellar mass companions to stars
in the future.Comment: LaTeX, 11 pages including 2 figures, accepted for publication in the
Astrophysical Journal Letter
Use of cohesive elements in fatigue analysis
Cohesive laws describe the resistance to incipient separation
of material surfaces. A cohesive finite element
is formulated on the basis of a particular cohesive
law. Cohesive elements are placed at the boundary
between adjacent standard volume finite elements
to model fatigue damage that leads to fracture at the
separation of the element boundaries per the cohesive
law. In this work, a cohesive model for fatigue
crack initiation is taken to be the irreversible loadingunloading
hysteresis that represents fatigue damage
occuring due to cyclic loads leading to the initiation of
small cracks. Various cohesive laws are reviewed and
one is selected that incorporates a hysteretic cyclic
loading that accounts for energetic dissipative mechanisms.
A mathematical representation is developed
based on an exponential effective load-separation cohesive
relationship. A three-dimensional cohesive element
is defined using this compliance relationship integrated
at four points on the mid-surface of the area
element. Implementation into finite element software
is discussed and particular attention is applied to numerical
convergence issues as the inflection point between
loading and 'unloading in the cohesive law is
encountered. A simple example of a displacementcontrolled
fatigue test is presented in a finite element
simulation. Comments are made on applications of
the method to prediction of fatigue life for engineering
structures such as pressure vessels and piping
Complementary Ansatz for the neutrino mass matrix
We propose a simple Ansatz for the three generation neutrino mass matrix
which is motivated from an SO(10) grand unified theory. The Ansatz can
be combined with information from neutrino oscillation experiments and bounds
on neutrinoless double beta decay to determine the neutrino masses themselves
and to reconstruct, with some assumptions, the matrix .Comment: 15 pages, RevteX, submitted to Phys. Rev.
The Scalar Sector and the Eta -> 3 Pi Problem
First, recent work on light scalar mesons, which is of possible interest in
connection with the strong coupling region of QCD is briefly discussed. Then a
very short highlighting of a paper concerned with an application to the eta ->
3 pi problem is presented.Comment: 7 pages LaTeX, 4 eps figures, talk at SCGT02 conference at Nagoy
A benign, low Z electron capture agent for negative ion TPCs
We have identified nitromethane (CHNO) as an effective electron
capture agent for negative ion TPCs (NITPCs).
We present drift velocity and longitudinal diffusion measurements for
negative ion gas mixtures using nitromethane as the capture agent.
Not only is nitromethane substantially more benign than the only other
identified capture agent, CS, but its low atomic number will enable the use
of the NITPC as a photoelectric X{}-ray polarimeter in the 1{}-10 keV band
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