29,492 research outputs found
Stable determination of an inclusion in an elastic body by boundary measurements (unabridged)
We consider the inverse problem of identifying an unknown inclusion contained
in an elastic body by the Dirichlet-to-Neumann map. The body is made by
linearly elastic, homogeneous and isotropic material. The Lam\'e moduli of the
inclusion are constant and different from those of the surrounding material.
Under mild a-priori regularity assumptions on the unknown defect, we establish
a logarithmic stability estimate. For the proof, we extend the approach used
for electrical and thermal conductors in a novel way. Main tools are
propagation of smallness arguments based on three-spheres inequality for
solutions to the Lam\'e system and refined local approximation of the
fundamental solution of the Lam\'e system in presence of an inclusion.Comment: 58 pages, 4 figures. This is the extended, and revised, version of a
paper submitted for publication in abridged for
On doubling inequalities for elliptic systems
We prove doubling inequalities for solutions of elliptic systems with an
iterated Laplacian as diagonal principal part and for solutions of the Lame'
system of isotropic linearized elasticity. These inequalities depend on global
properties of the solutions.Comment: 13 pages, submitted for publicatio
Significance Of Deuteron Breakup In A Halo Transfer Reaction
We discuss the quasi-adiabatic approximations to the three-body wavefunction
in breakup processes, clarifying the assumptions underlying the model. This
suggests alternative approximation schemes. Using different theoretical
three-body models, calculated differential cross section angular distributions
for the Be-11(p,d) reaction,for which new preliminary data have been reported
at 35 MeV, are presented. We show that calculations are sensitive to the
inclusion of deuteron breakup and to the breakup model used, particularly if
used to deduce absolute spectroscopic information on the 0{+} and 2{+} Be-10
core state parentages. There is also considerable sensitivity to the model used
in calculations of the relative cross sections to the two states.Comment: LaTEX (uses article.sty), 16 pages and 3 figures (EPS format). Please
check http://physics.gantep.edu.tr/~nuclear/publications.html for other other
studies of Nuclear Physics Group at University of Gaziante
Computing Volume Bounds of Inclusions by EIT Measurements
The size estimates approach for Electrical Impedance Tomography (EIT) allows
for estimating the size (area or volume) of an unknown inclusion in an
electrical conductor by means of one pair of boundary measurements of voltage
and current. In this paper we show by numerical simulations how to obtain such
bounds for practical application of the method. The computations are carried
out both in a 2D and a 3D setting.Comment: 20 pages with figure
A determination of the molar gas constant R by acoustic thermometry in helium
We have determined the acoustic and microwave frequencies of a misaligned spherical resonator
maintained near the temperature of the triple point of water and filled with helium with carefully
characterized molar mass M = (4.002 6032 ± 0.000 0015) g mol-1, with a relative standard uncertainty
ur(M) = 0.37Ă—10-6. From these data and traceable thermometry we estimate the speed of sound in our
sample of helium at TTPW = 273.16 K and zero pressure to be u0
2 = (945 710.45 ± 0.85) m2 s-2 and
correspondingly deduce the value R = (8.314 4743 ± 0.000 0088) J mol-1 K-1 for the molar gas
constant. We estimate the value k = R/NA = (1.380 6508 ± 0.000 0015) × 10-23 J K-1 for the Boltzmann
constant using the currently accepted value of the Avogadro constant NA. These estimates of R and k,
with a relative standard uncertainty of 1.06 Ă— 10-6, are 1.47 parts in 106 above the values recommended
by CODATA in 2010
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