6,047 research outputs found
Applications of elastic-viscoplastic constitutive models in dynamic analyses of crack run-arrest events
Applications of nonlinear techniques to the first series of six HSST wide-plate crack-arrest tests that were performed are described. The experiments include crack initiations at low temperatures and relatively long (20 cm) cleavage propagation phases which are terminated by arrest in high temperature regions. Crack arrest are then followed by ductile tearing events. Consequently, the crack front regions are exposed to wide ranges of strain rates and temperatures
Hallermann-Streiff syndrome - Clinical and prognostic considerations
A patient with the Hallermann-Streiff syndrome showed significant findings, including demonstration of decreased thoracic compliance and a marked response of growth hormone to arginine stimulation. No metabolic or chromosomal defect could be demonstrated in this patient
Transition from subbarrier to deep subbarrier regimes in heavy-ion fusion reactions
We analyze the recent experimental data of heavy-ion fusion cross sections
available up to deep subbarrier energies in order to discuss the threshold
incident energy for a deep subbarrier fusion hindrance phenomenon. To this end,
we employ a one-dimensional potential model with a Woods-Saxon internuclear
potential. Fitting the experimental data in two different energy regions with
different Woods-Saxon potentials, we define the threshold energy as an
intersect of the two fusion excitation functions. We show that the threshold
energies so extracted are in good agreement with the empirical systematics as
well as with the values of the Krappe-Nix-Sierk (KNS) potential at the touching
point. We also discuss the asymptotic energy shift of fusion cross sections
with respect to the potential model calculations, and show that it decreases
with decreasing energies in the deep subbarrier region although it takes a
constant value at subbarrier energies.Comment: 4 pages, 4 figure
Heavy-quark axial charges to non-leading order
We combine Witten's renormalization group with the matching conditions of
Bernreuther and Wetzel to calculate at next-to-leading order the complete
heavy-quark contribution to the neutral-current axial-charge measurable in
neutrino-proton elastic scattering. Our results are manifestly renormalization
group invariant.Comment: 5 pages, revtex styl
Interplay of Spin and Orbital Angular Momentum in the Proton
We derive the consequences of the Myhrer-Thomas explanation of the proton
spin problem for the distribution of orbital angular momentum on the valence
and sea quarks. After QCD evolution these results are found to be in very good
agreement with both recent lattice QCD calculations and the experimental
constraints from Hermes and JLab
Spin and orbital angular momentum of the proton
Since the announcement of the proton spin crisis by the European Muon
Collaboration there has been considerable progress in unravelling the
distribution of spin and orbital angular momentum within the proton. We review
the current status of the problem, showing that not only have strong upper
limits have been placed on the amount of polarized glue in the proton but that
the experimental determination of the spin content has become much more
precise. It is now clear that the origin of the discrepancy between experiment
and the naive expectation of the fraction of spin carried by the quarks and
anti-quarks in the proton lies in the non-perturbative structure of the proton.
We explain how the features expected in a modern, relativistic and chirally
symmetric description of nucleon structure naturally explain the current data.
The consequences of this explanation for the presence of orbital angular
momentum on quarks and gluons is reviewed and comparison made with recent
results from lattice QCD and experimental data.Comment: Lectures at Aligarh University (4th DAE-BRNS Workshop on Hadron
Physics, Feb 18-21, 200
Gauge symmetry and the EMC spin effect
We emphasise the EMC spin effect as a problem of symmetry and discuss the
renormalisation of the axial tensor operators. This involves the
generalisation of the Adler-Bell-Jackiw anomaly to each of these operators. We
find that the contribution of the axial anomaly to the spin dependent structure
function scales at . This means that the anomaly
can be a large effect in . Finally we discuss the jet signature of the
anomaly.Comment: 17 pages, Latex, Cavendish preprint HEP 93/
Specific Resistance of Pd/Ir Interfaces
From measurements of the current-perpendicular-to-plane (CPP) total specific
resistance (AR = area times resistance) of sputtered Pd/Ir multilayers, we
derive the interface specific resistance, 2AR(Pd/Ir) = 1.02 +/- 0.06 fOhmm^2,
for this metal pair with closely similar lattice parameters. Assuming a single
fcc crystal structure with the average lattice parameter, no-free-parameter
calculations, including only spd orbitals, give for perfect interfaces,
2AR(Pd/Ir)(Perf) = 1.21 +/-0.1 fOhmm^2, and for interfaces composed of two
monolayers of a random 50%-50% alloy, 2AR(Pd/Ir)(50/50) = 1.22 +/- 0.1 fOhmm^2.
Within mutual uncertainties, these values fall just outside the range of the
experimental value. Updating to add f-orbitals gives 2AR(Pd/Ir)(Perf) = 1.10
+/- 0.1 fOhmm^2 and 2AR(Pd/Ir)(50-50) = 1.13 +/- 0.1 fOhmm^2, values now
compatible with the experimental one. We also update, with f-orbitals,
calculations for other pairsComment: 3 pages, 1 figure, in press in Applied Physics Letter
Opaque Service Virtualisation: A Practical Tool for Emulating Endpoint Systems
Large enterprise software systems make many complex interactions with other
services in their environment. Developing and testing for production-like
conditions is therefore a very challenging task. Current approaches include
emulation of dependent services using either explicit modelling or
record-and-replay approaches. Models require deep knowledge of the target
services while record-and-replay is limited in accuracy. Both face
developmental and scaling issues. We present a new technique that improves the
accuracy of record-and-replay approaches, without requiring prior knowledge of
the service protocols. The approach uses Multiple Sequence Alignment to derive
message prototypes from recorded system interactions and a scheme to match
incoming request messages against prototypes to generate response messages. We
use a modified Needleman-Wunsch algorithm for distance calculation during
message matching. Our approach has shown greater than 99% accuracy for four
evaluated enterprise system messaging protocols. The approach has been
successfully integrated into the CA Service Virtualization commercial product
to complement its existing techniques.Comment: In Proceedings of the 38th International Conference on Software
Engineering Companion (pp. 202-211). arXiv admin note: text overlap with
arXiv:1510.0142
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