2,765 research outputs found
Crogenic alloy screening Interim report
Evaluation of mechanical properties and fracture strength of aluminum alloys and stainless stee
Determination of low-temperature fatigue properties of structural metal alloys Final report, Jul. 1964 - Aug. 1965
Fatigue testing and determination of low temperature properties of structural metal alloys - aluminum alloy, stainless steel, and nickel alloy
Preface: School Facilities - New Solutions to New Challenges
During the period from about 1950 to 1970, major questions relating to elementary and secondary school capital improvement planning revolved to a considerable extent around issues of expansion
Icosahedral packing of polymer-tethered nanospheres and stabilization of the gyroid phase
We present results of molecular simulations that predict the phases formed by
the self-assembly of model nanospheres functionalized with a single polymer
"tether", including double gyroid, perforated lamella and crystalline bilayer
phases. We show that microphase separation of the immiscible tethers and
nanospheres causes confinement of the nanoparticles, which promotes local
icosahedral packing that stabilizes the gyroid and perforated lamella phases.
We present a new metric for determining the local arrangement of particles
based on spherical harmonic "fingerprints", which we use to quantify the extent
of icosahedral ordering.Comment: 8 pages, 4 figure
Self Assembly of Soft Matter Quasicrystals and Their Approximants
The surprising recent discoveries of quasicrystals and their approximants in
soft matter systems poses the intriguing possibility that these structures can
be realized in a broad range of nano- and micro-scale assemblies. It has been
theorized that soft matter quasicrystals and approximants are largely
entropically stabilized, but the thermodynamic mechanism underlying their
formation remains elusive. Here, we use computer simulation and free energy
calculations to demonstrate a simple design heuristic for assembling
quasicrystals and approximants in soft matter systems. Our study builds on
previous simulation studies of the self-assembly of dodecagonal quasicrystals
and approximants in minimal systems of spherical particles with complex,
highly-specific interaction potentials. We demonstrate an alternative
entropy-based approach for assembling dodecagonal quasicrystals and
approximants based solely on particle functionalization and shape, thereby
recasting the interaction-potential-based assembly strategy in terms of
simpler-to-achieve bonded and excluded-volume interactions. Here, spherical
building blocks are functionalized with mobile surface entities to encourage
the formation of structures with low surface contact area, including
non-close-packed and polytetrahedral structures. The building blocks also
possess shape polydispersity, where a subset of the building blocks deviate
from the ideal spherical shape, discouraging the formation of close-packed
crystals. We show that three different model systems with both of these
features -- mobile surface entities and shape polydispersity -- consistently
assemble quasicrystals and/or approximants. We argue that this design strategy
can be widely exploited to assemble quasicrystals and approximants on the nano-
and micro- scales. In addition, our results further elucidate the formation of
soft matter quasicrystals in experiment.Comment: 12 pages 6 figure
The arctic circle boundary and the Airy process
We prove that the, appropriately rescaled, boundary of the north polar region
in the Aztec diamond converges to the Airy process. The proof uses certain
determinantal point processes given by the extended Krawtchouk kernel. We also
prove a version of Propp's conjecture concerning the structure of the tiling at
the center of the Aztec diamond.Comment: Published at http://dx.doi.org/10.1214/009117904000000937 in the
Annals of Probability (http://www.imstat.org/aop/) by the Institute of
Mathematical Statistics (http://www.imstat.org
Cryogenic alloy screening Final report
Mechanical properties of cryogenically stretched type 301 stainless steel and aluminum alloys 2021-T81 and X7007-T
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