258 research outputs found
Identification of Boundary Conditions Using Natural Frequencies
The present investigation concerns a disc of varying thickness of whose
flexural stiffness varies with the radius according to the law , where and are constants. The problem of finding boundary
conditions for fastening this disc, which are inaccessible to direct
observation, from the natural frequencies of its axisymmetric flexural
oscillations is considered. The problem in question belongs to the class of
inverse problems and is a completely natural problem of identification of
boundary conditions. The search for the unknown conditions for fastening the
disc is equivalent to finding the span of the vectors of unknown conditions
coefficients. It is shown that this inverse problem is well posed. Two theorems
on the uniqueness and a theorem on stability of the solution of this problem
are proved, and a method for establishing the unknown conditions for fastening
the disc to the walls is indicated. An approximate formula for determining the
unknown conditions is obtained using first three natural frequencies. The
method of approximate calculation of unknown boundary conditions is explained
with the help of three examples of different cases for the fastening the disc
(rigid clamping, free support, elastic fixing).
Keywords: Boundary conditions, a disc of varying thickness,inverse problem,
Plucker condition.Comment: 19 page
Feto-Placental Atherosclerotic Lesions in Intrauterine Fetal Demise: Role of Parental Cigarette Smoking
The atherogenic effect of cigarette smoking is already recognizable in coronary arteries of fetuses in the last gestational weeks. In this study we analyzed the atherogenic effect of mother’s and father’s smoking habit on coronary arteries and even on adnexa of 30 human fresh fetuses died from 32 to 41 gestational weeks. In 12 cases only the mothers of the victims were cigarette smokers, in 7 cases only the fathers were smokers, whereas in 11 cases nobody smoked
Two-pion Bose-Einstein correlations in central Pb-Pb collisions at = 2.76 TeV
The first measurement of two-pion Bose-Einstein correlations in central Pb-Pb
collisions at TeV at the Large Hadron Collider is
presented. We observe a growing trend with energy now not only for the
longitudinal and the outward but also for the sideward pion source radius. The
pion homogeneity volume and the decoupling time are significantly larger than
those measured at RHIC.Comment: 17 pages, 5 captioned figures, 1 table, authors from page 12,
published version, figures at
http://aliceinfo.cern.ch/ArtSubmission/node/388
Suppression of charged particle production at large transverse momentum in central Pb-Pb collisions at TeV
Inclusive transverse momentum spectra of primary charged particles in Pb-Pb
collisions at = 2.76 TeV have been measured by the ALICE
Collaboration at the LHC. The data are presented for central and peripheral
collisions, corresponding to 0-5% and 70-80% of the hadronic Pb-Pb cross
section. The measured charged particle spectra in and GeV/ are compared to the expectation in pp collisions at the same
, scaled by the number of underlying nucleon-nucleon
collisions. The comparison is expressed in terms of the nuclear modification
factor . The result indicates only weak medium effects ( 0.7) in peripheral collisions. In central collisions,
reaches a minimum of about 0.14 at -7GeV/ and increases
significantly at larger . The measured suppression of high- particles is stronger than that observed at lower collision energies,
indicating that a very dense medium is formed in central Pb-Pb collisions at
the LHC.Comment: 15 pages, 5 captioned figures, 3 tables, authors from page 10,
published version, figures at http://aliceinfo.cern.ch/ArtSubmission/node/98
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