283,506 research outputs found
Application of the linear matching method to creep-fatigue failure analysis of cruciform weldment manufactured of the austenitic steel AISI type 316N(L)
This paper demonstrates the recent extension of the Linear Matching Method (LMM) to include cyclic creep assessment [1] in application to a creep-fatigue analysis of a cruciform weldment made of the stainless steel AISI type 316N(L). The obtained results are compared with the results of experimental studies implemented by Bretherton et al. [2] with the overall objective to identify fatigue strength reduction factors (FSRF) of austenitic weldments for further design application. These studies included a series of strain-controlled tests at 550Β°C with different combinations of reversed bending moment and dwell time Ξt. Five levels of reversed bending moment histories corresponding to defined values of total strain range ΞΞ΅tot in remote parent material (1%, 0.6%, 0.4%, 0.3%, 0.25%) were used in combination with three variants of creep-fatigue conditions: pure fatigue, 1 hour and 5 hours of dwell period Ξt of hold in tension. An overview of previous works devoted to analysis and simulation of these experiments [2] and highlight of the LMM development progress could be found in [3]
Factorizations of Matrices Over Projective-free Rings
An element of a ring is called strongly -clean provided that it
can be written as the sum of an idempotent and an element in that
commute. We characterize, in this article, the strongly -cleanness of
matrices over projective-free rings. These extend many known results on
strongly clean matrices over commutative local rings
Stein meets Malliavin in normal approximation
Stein's method is a method of probability approximation which hinges on the
solution of a functional equation. For normal approximation the functional
equation is a first order differential equation. Malliavin calculus is an
infinite-dimensional differential calculus whose operators act on functionals
of general Gaussian processes. Nourdin and Peccati (2009) established a
fundamental connection between Stein's method for normal approximation and
Malliavin calculus through integration by parts. This connection is exploited
to obtain error bounds in total variation in central limit theorems for
functionals of general Gaussian processes. Of particular interest is the fourth
moment theorem which provides error bounds of the order
in the central limit theorem for elements
of Wiener chaos of any fixed order such that
. This paper is an exposition of the work of Nourdin and
Peccati with a brief introduction to Stein's method and Malliavin calculus. It
is based on a lecture delivered at the Annual Meeting of the Vietnam Institute
for Advanced Study in Mathematics in July 2014.Comment: arXiv admin note: text overlap with arXiv:1404.478
Systematic study of the symmetry energy coefficient in finite nuclei
The symmetry energy coefficients in finite nuclei have been studied
systematically with a covariant density functional theory (DFT) and compared
with the values calculated using several available mass tables. Due to the
contamination of shell effect, the nuclear symmetry energy coefficients
extracted from the binding energies have large fluctuations around the nuclei
with double magic numbers. The size of this contamination is shown to be
smaller for the nuclei with larger isospin value. After subtracting the shell
effect with the Strutinsky method, the obtained nuclear symmetry energy
coefficients with different isospin values are shown to decrease smoothly with
the mass number and are subsequently fitted to the relation . The resultant volume and
surface coefficients from axially deformed covariant DFT calculations are
and MeV respectively. The ratio is in good
agreement with the value derived from the previous calculations with the
non-relativistic Skyrme energy functionals. The coefficients and
corresponding to several available mass tables are also extracted. It is shown
that there is a strong linear correlation between the volume and surface
coefficients and the ratios are in between for all
the cases.Comment: 16 pages, 6 figure
Poisson process approximation: From Palm theory to Stein's method
This exposition explains the basic ideas of Stein's method for Poisson random
variable approximation and Poisson process approximation from the point of view
of the immigration-death process and Palm theory. The latter approach also
enables us to define local dependence of point processes [Chen and Xia (2004)]
and use it to study Poisson process approximation for locally dependent point
processes and for dependent superposition of point processes.Comment: Published at http://dx.doi.org/10.1214/074921706000001076 in the IMS
Lecture Notes Monograph Series
(http://www.imstat.org/publications/lecnotes.htm) by the Institute of
Mathematical Statistics (http://www.imstat.org
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