2,224 research outputs found
Porous LSCF/Dense 3YSZ Interface Fracture Toughness Measured by Single Cantilever Beam Wedge Test
Sandwich specimens were prepared by firing a thin inter-layer of porous
La0.6Sr0.4Co0.2Fe0.8O3-d (LSCF) to bond a thin tetragonal yttria-stabilised
zirconia (YSZ) beam to a thick YSZ substrate. Fracture of the joint was
evaluated by introducing a wedge between the two YSZ adherands so that the
stored energy in the thin YSZ cantilever beam drives a stable crack in the
adhesive bond and allows the critical energy release rate for crack extension
(fracture toughness) to be measured. The crack path in most specimens showed a
mixture of adhesive failure (at the YSZ-LSCF interface) and cohesive failure
(within the LSCF). It was found that the extent of adhesive fracture increased
with firing temperature and decreased with LSCF layer thickness. The adhesive
failures were mainly at the interface between the LSCF and the thin YSZ beam
and FEM modelling revealed that this is due to asymmetric stresses in the LSCF.
Within the firing temperature range of 1000-1150C, the bonding fracture
toughness appears to have a strong dependence on firing temperature. However,
the intrinsic adhesive fracture toughness of the LSCF/YSZ interface was
estimated to be 11 Jm2 and was not firing temperature dependent within the
temperature range investigated.Comment: 13 figures, 1 table, journal paper publishe
Thermodynamics in the universe described by the emergence of the space and the energy balance relation
It has previously been shown that it is more general to describe the
evolution of the universe based on the emergence of the space and the energy
balance relation. Here we investigate the thermodynamic properties of the
universe described by such a model. We show that the first law of
thermodynamics and the generalized second law of thermodynamics (GSLT) are both
satisfied and the weak energy condition are also fulfilled for two typical
examples. Finally we examine the physical consistency for the present model.Comment: 9 pages, 2 figure
Effects of tidally enhanced stellar wind on the horizontal branch morphology of globular clusters
Metallicity is the first parameter to influence the horizontal branch (HB)
morphology of globular clusters (GCs). It has been found, however, that some
other parameters may also play an important role in affecting the morphology.
While the nature of these important parameters remains unclear, they are
believed to be likely correlated with wind mass-loss of red giants, since this
mass loss determines their subsequent locations on the HB. Unfortunately, the
mass loss during the red giant stages of the stellar evolution is poorly
understood at present. The stellar winds of red giants may be tidally enhanced
by companion stars if they are in binary systems. We investigate evolutionary
consequences of red giants in binaries by including tidally enhanced stellar
winds, and examine the effects on the HB morphology of GCs. We find that red,
blue, and extreme horizontal branch stars are all produced under the effects of
tidally enhanced stellar wind without any additional assumptions on the
mass-loss dispersion. Furthermore, the horizontal branch morphology is found to
be insensitive to the tidal enhancement parameter, Bw. We compare our
theoretical results with the observed horizontal branch morphology of globular
cluster NGC 2808, and find that the basic morphology of the horizontal branch
can be well reproduced. The number of blue horizontal branch stars in our
calculations, however, is lower than that of NGC 2808.Comment: 7 pages, 4 figures, 2 tables, accepted for publication in Astronomy &
Astrophysic
A generalized public goods game with coupling of individual ability and project benefit
Facing a heavy task, any single person can only make a limited contribution
and team cooperation is needed. As one enjoys the benefit of the public goods,
the potential benefits of the project are not always maximized and may be
partly wasted. By incorporating individual ability and project benefit into the
original public goods game, we study the coupling effect of the four
parameters, the upper limit of individual contribution, the upper limit of
individual benefit, the needed project cost and the upper limit of project
benefit on the evolution of cooperation. Coevolving with the individual-level
group size preferences, an increase in the upper limit of individual benefit
promotes cooperation while an increase in the upper limit of individual
contribution inhibits cooperation. The coupling of the upper limit of
individual contribution and the needed project cost determines the critical
point of the upper limit of project benefit, where the equilibrium frequency of
cooperators reaches its highest level. Above the critical point, an increase in
the upper limit of project benefit inhibits cooperation. The evolution of
cooperation is closely related to the preferred group-size distribution. A
functional relation between the frequency of cooperators and the dominant group
size is found
Population-based Algorithm Portfolios with automated constituent algorithms selection
AbstractPopulation-based Algorithm Portfolios (PAP) is an appealing framework for integrating different Evolutionary Algorithms (EAs) to solve challenging numerical optimization problems. Particularly, PAP has shown significant advantages to single EAs when a number of problems need to be solved simultaneously. Previous investigation on PAP reveals that choosing appropriate constituent algorithms is crucial to the success of PAP. However, no method has been developed for this purpose. In this paper, an extended version of PAP, namely PAP based on Estimated Performance Matrix (EPM-PAP) is proposed. EPM-PAP is equipped with a novel constituent algorithms selection module, which is based on the EPM of each candidate EAs. Empirical studies demonstrate that the EPM-based selection method can successfully identify appropriate constituent EAs, and thus EPM-PAP outperformed all single EAs considered in this work
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