149 research outputs found
10 tips and tricks to improve the communication of marine conservation science with a clear and attractive visual story
Lattice Kinetics of Diffusion-Limited Coalescence and Annihilation with Sources
We study the 1D kinetics of diffusion-limited coalescence and annihilation
with back reactions and different kinds of particle input. By considering the
changes in occupation and parity of a given interval, we derive sets of
hierarchical equations from which exact expressions for the lattice coverage
and the particle concentration can be obtained. We compare the mean-field
approximation and the continuum approximation to the exact solutions and we
discuss their regime of validity.Comment: 24 pages and 3 eps figures, Revtex, accepted for publication in J.
Phys.
Uncertainty Propagation in Integrated Airframe Propulsion System Analysis for Hypersonic Vehicles
Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/90676/1/AIAA-2011-2394-420.pd
LANSCE Digital Low Level RF Upgrade
Incremental upgrades of the legacy low level RF (LLRF) equipment-50 years for
the Los Alamos Neutron Science Center (LANSCE)-involves challenges and problems
not seen with new and total replacement opportunities. The digital LLRF upgrade
at LANSCE has deployed 30 of the 53 required systems as of September 2022. This
paper describes the performance of the digital upgrade, current status, and
future installations along with the technical challenges, including unexpected
challenges, associated with deploying new digital systems in conjunction with
legacy analog equipment. In addition, this paper discusses the operational
details of simultaneous multi-energy beam operations using high energy
re-bunching, beam-type specific set points and simultaneous multi-beam
operations at LANSCE. The adaptability of the digital LLRF systems is essential
as the design is able to accommodate new control and beam parameters associated
with future systems without significant hardware modifications such as the
expected LANSCE Modernization Program. This adaptability of the digital LLRF
technology was recently demonstrated with the Module 1, 201.25-MHz high-power
RF upgrade completed in 2021.Comment: Talk presented at LLRF Workshop 2022 (LLRF2022, arXiv:2208.13680
Multiconfigurational nature of 5f orbitals in uranium and plutonium intermetallics
Uranium and plutonium's 5f electrons are tenuously poised between strongly
bonding with ligand spd-states and residing close to the nucleus. The unusual
properties of these elements and their compounds (eg. the six different
allotropes of elemental plutonium) are widely believed to depend on the related
attributes of f-orbital occupancy and delocalization, for which a quantitative
measure is lacking. By employing resonant x-ray emission spectroscopy (RXES)
and x-ray absorption near-edge structure (XANES) spectroscopy and making
comparisons to specific heat measurements, we demonstrate the presence of
multiconfigurational f-orbital states in the actinide elements U and Pu, and in
a wide range of uranium and plutonium intermetallic compounds. These results
provide a robust experimental basis for a new framework for understanding the
strongly-correlated behavior of actinide materials.Comment: 30 pages, concatenated article and supporting information, 10 figure
Controllable chirality-induced geometrical Hall effect in a frustrated highly-correlated metal
A current of electrons traversing a landscape of localized spins possessing
non-coplanar magnetic order gains a geometrical (Berry) phase which can lead to
a Hall voltage independent of the spin-orbit coupling within the material--a
geometrical Hall effect. We show that the highly-correlated metal UCu5
possesses an unusually large controllable geometrical Hall effect at T<1.2K due
to its frustration-induced magnetic order. The magnitude of the Hall response
exceeds 20% of the \nu=1 quantum Hall effect per atomic layer, which translates
into an effective magnetic field of several hundred Tesla acting on the
electrons. The existence of such a large geometric Hall response in UCu5 opens
a new field of inquiry into the importance of the role of frustration in
highly-correlated electron materials.Comment: article and supplemental informatio
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