5,030 research outputs found
Grinding as an approach to the production of high-strength, dispersion-strengthened nickel-base alloys
Mechanical process produces dispersion-strengthened metal alloys. Power surface contamination during milling is removed by a cleaning method that involves heating thin shapes or partially-compacted milled powder blends in hydrogen to carefully controlled temperature schedules
Universal collisionless transport of graphene
The impact of the electron-electron Coulomb interaction on the optical
conductivity of graphene has led to a controversy that calls into question the
universality of collisionless transport in this and other Dirac materials.
Using a lattice calculation that avoids divergences present in previous nodal
Dirac approaches, our work settles this controversy and obtains results in
quantitative agreement with experiment over a wide frequency range. We also
demonstrate that dimensional regularization methods agree, as long as the
scaling properties of the conductivity and the regularization of the theory in
modified dimension are correctly implemented. Tight-binding lattice and nodal
Dirac theory calculations are shown to coincide at low energies even when the
non-zero size of the atomic orbital wave function is included, conclusively
demonstrating the universality of the optical conductivity of graphene.Comment: 4+ pages,4 figures; includes Supplemental Material (18 pages, 2
figures
Woman in the Mirror; Precious Child of God or Just a Rib?
This thesis entitled, “Woman in the Mirror: Precious Child of God, or Just a Rib?” is based on a request from colleagues to create a curriculum as a companion piece to the Rev. Dr. Kevin Frederick’s curriculum, “Men in the Mirror: Orienting Our Lives Toward a Christ-Centered Masculinity.” The curriculum will be used by pastors and pastoral counselors working with women who struggle with self-esteem and/or are victims of domestic violence. This thesis explores the problem that some women seem to lack a clear understanding of their position in the kingdom of God. Looking at how women understood God, their identity as followers of Jesus Christ, and how they live their faith in their identity, this thesis used qualitative research and a triangulation of a questionnaire, an inventory tool and interviews with women. The results of the research provided the data necessary to create the content for the curriculum
Production and processing of Cu-Cr-Nb alloys
A new Cu-based alloy possessing high strength, high conductivity, and good stability at elevated temperatures was recently produced. This paper details the melting of the master alloys, production of rapidly solidified ribbon, and processing of the ribbon to sheet by hot pressing and hot rolling
Antechamber facilitates loading and unloading of vacuum furnace
Antechamber facilitates the use of a furnace in which materials are heat treated in a high vacuum or a gas atmosphere. It has a high vacuum pumping system, a means for backfilling with a selected gas, an access door, glove ports, and a motor driven platform
Emergent Critical Phase and Ricci Flow in a 2D Frustrated Heisenberg Model
We introduce a two-dimensional frustrated Heisenberg antiferromagnet on
interpenetrating honeycomb and triangular lattices. Classically the two
sublattices decouple, and "order from disorder" drives them into a coplanar
state. Applying Friedan's geometric approach to nonlinear sigma models, we show
that the scaling of the spin-stiffnesses corresponds to the Ricci flow of a 4D
metric tensor. At low temperatures, the relative phase between the spins on the
two sublattices is described by a six-state clock model with an emergent
critical phase.Comment: 4+ pages, 2 figure
Role of soil moisture versus recent climate change for the 2010 heat wave in western Russia
The severe 2010 heat wave in western Russia was found to be influenced by anthropogenic climate change. Additionally, soil moisture-temperature feedbacks were deemed important for the buildup of the exceptionally high temperatures. We quantify the relative role of both factors by applying the probabilistic event attribution framework and analyze ensemble simulations to distinguish the effect of climate change and the 2010 soil moisture conditions for annual maximum temperatures. The dry 2010 soil moisture alone has increased the risk of a severe heat wave in western Russia sixfold, while climate change from 1960 to 2000 has approximately tripled it. The combined effect of climate change and 2010 soil moisture yields a 13 times higher heat wave risk. We conclude that internal climate variability causing the dry 2010 soil moisture conditions formed a necessary basis for the extreme heat wave
Vacuum energy in the presence of a magnetic string with delta function profile
We present a calculation of the ground state energy of massive spinor fields
and massive scalar fields in the background of an inhomogeneous magnetic string
with potential given by a delta function. The zeta functional regularization is
used and the lowest heat kernel coefficients are calculated. The rest of the
analytical calculation adopts the Jost function formalism. In the numerical
part of the work the renormalized vacuum energy as a function of the radius
of the string is calculated and plotted for various values of the strength of
the potential. The sign of the energy is found to change with the radius. For
both scalar and spinor fields the renormalized energy shows no logarithmic
behaviour in the limit , as was expected from the vanishing of the heat
kernel coefficient , which is not zero for other types of profiles.Comment: 30 pages, 10 figure
- …