26,276 research outputs found
Non-commutative p-adic L-functions for supersingular primes
Let E/Q be an elliptic curve with good supersingular reduction at p with
a_p(E)=0. We give a conjecture on the existence of analytic plus and minus
p-adic L-functions of E over the Zp-cyclotomic extension of a finite Galois
extension of Q where p is unramified. Under some technical conditions, we adopt
the method of Bouganis and Venjakob for p-ordinary CM elliptic curves to
construct such functions for a particular non-abelian extension.Comment: 13 pages; some minor corrections; to appear in International Journal
of Number Theor
On positive solutions and the Omega limit set for a class of delay differential equations
This paper studies the positive solutions of a class of delay differential
equations with two delays. These equations originate from the modeling of
hematopoietic cell populations. We give a sufficient condition on the initial
function for such that the solution is positive for all time .
The condition is "optimal". We also discuss the long time behavior of these
positive solutions through a dynamical system on the space of continuous
functions. We give a characteristic description of the limit set of
this dynamical system, which can provide informations about the long time
behavior of positive solutions of the delay differential equation.Comment: 15 pages, 2 figure
Heat transfer and pressure drop in blade cooling channels with turbulence promoters
Repeated rib roughness elements have been used in advanced turbine cooling designs to enhance the internal heat transfer. Often the ribs are perpendicular to the main flow direction so that they have an angle-of-attack of 90 deg. The objective of the project was to investigate the effect of rib angle-of-attack on the pressure drop and the average heat transfer coefficients in a square duct with two opposite rib-roughned walls for Reynolds number varied from 8000 to 80,000. The rib height-to-equivalent diameter ratio (e/D) was kept at a constant value of 0.063, the rib pitch-to-height ratio (P/e) was varied from 10 to 20, and the rib angle-of-attack (alpha) was varied from 90 deg to 60 deg to 45 deg to 30 deg respectively. Two types of entrance conditions were examined, namely, long duct and sudden contraction. The heat transfer coefficient distribution on the smooth side wall and the rough side wall at the entrance and the fully developed regions were measured. Thermal performance comparison indicated that the pumping power requirement for the rib with an oblique angle to the flow (alpha = 45 deg to 30 deg) was about 20 to 50 percent lower than the rib with a 90 deg angle to the flow for a given heat transfer duty
Spherical to deformed shape transition in the nucleon-pair shell model
A study of the shape transition from spherical to axially deformed nuclei in
the even Ce isotopes using the nucleon-pair approximation of the shell model is
reported. As long as the structure of the dominant collective pairs is
determined using a microscopic framework appropriate to deformed nuclei, the
model is able to produce a shape transition. However, the resulting transition
is too rapid, with nuclei that should be transitional being fairly well
deformed, perhaps reflecting the need to maintain several pairs with each
angular momentum.Comment: 7 pages, 5 figure
Inverse Spin Hall Effect by Spin Injection
Motivated by a recent experiment[Nature {\bf 442}, 176 (2006)], we present a
quantitative microscopic theory to investigate the inverse spin-Hall effect
with spin injection into aluminum considering both intrinsic and extrinsic
spin-orbit couplings using the orthogonalized-plane-wave method. Our
theoretical results are in good agreement with the experimental data. It is
also clear that the magnitude of the anomalous Hall resistivity is mainly due
to contributions from extrinsic skew scattering, while its spatial variation is
determined by the intrinsic spin-orbit coupling.Comment: 5 pages, 3 figure
Factors Responsible for the Stability and the Existence of a Clean Energy Gap of a Silicon Nanocluster
We present a critical theoretical study of electronic properties of silicon
nanoclusters, in particular the roles played by symmetry, relaxation, and
hydrogen passivation on the the stability, the gap states and the energy gap of
the system using the order-N [O(N)] non-orthogonal tight-binding molecular
dynamics and the local analysis of electronic structure.Comment: 26 pages including figure
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