10,143 research outputs found
Phase-change materials handbook
Handbook describes relationship between phase-change materials and more conventional thermal control techniques and discusses materials' space and terrestrial applications. Material properties of most promising phase-change materials and purposes and uses of metallic filler materials in phase-change material composites are provided
The bearable lightness of being
How are philosophical questions about what kinds of things there are to be understood and how are they to be answered? This paper defends broadly Fregean answers to these questions. Ontological categories-such as object, property, and relation-are explained in terms of a prior logical categorization of expressions, as singular terms, predicates of varying degree and level, etc. Questions about what kinds of object, property, etc., there are are, on this approach, reduce to questions about truth and logical form: for example, the question whether there are numbers is the question whether there are true atomic statements in which expressions function as singular terms which, if they have reference at all, stand for numbers, and the question whether there are properties of a given type is a question about whether there are meaningful predicates of an appropriate degree and level. This approach is defended against the objection that it must be wrong because makes what there depend on us or our language. Some problems confronting the Fregean approach-including Frege's notorious paradox of the concept horse-are addressed. It is argued that the approach results in a modest and sober deflationary understanding of ontological commitments
Evaluation of absorption cycle for space station environmental control system application Interim report
Zero-gravity absorption refrigeration system design and performance testing for space station environmental control applicatio
Many-body effects on the capacitance of multilayers made from strongly correlated materials
Recent work by Kopp and Mannhart on novel electronic systems formed at oxide
interfaces has shown interesting effects on the capacitances of these devices.
We employ inhomogeneous dynamical mean-field theory to calculate the
capacitance of multilayered nanostructures. These multilayered nanostructures
are composed of semi-infinite metallic leads coupled via a strongly correlated
dielectric barrier region. The barrier region can be adjusted from a metallic
regime to a Mott insulator through adjusting the interaction strength. We
examine the effects of varying the barrier width, temperature, potential
difference, screening length, and chemical potential. We find that the
interaction strength has a relatively strong effect on the capacitance, while
the potential and temperature show weaker dependence.Comment: 19 pages, 7 figures, REVTe
Hot phonon decay in supported and suspended exfoliated graphene
Near infrared pump-probe spectroscopy has been used to measure the ultrafast
dynamics of photoexcited charge carriers in monolayer and multilayer graphene.
We observe two decay processes occurring on 100 fs and 2 ps timescales. The
first is attributed to the rapid electron-phonon thermalisation in the system.
The second timescale is found to be due to the slow decay of hot phonons. Using
a simple theoretical model we calculate the hot phonon decay rate and show that
it is significantly faster in monolayer flakes than in multilayer ones. In
contrast to recent claims, we show that this enhanced decay rate is not due to
the coupling to substrate phonons, since we have also seen the same effect in
suspended flakes. Possible intrinsic decay mechanisms that could cause such an
effect are discussed.Comment: 4 pages, 3 figure
A Variational Principle for Eigenvalue Problems of Hamiltonian Systems
We consider the bifurcation problem with two point
boundary conditions where is a general nonlinear term which may also
depend on the eigenvalue . We give a variational characterization of
the bifurcating branch as a function of the amplitude of the
solution. As an application we show how it can be used to obtain simple
approximate closed formulae for the period of large amplitude oscillations.Comment: 10 pages Revtex, 2 figures include
Complete chaotic synchronization in mutually coupled time-delay systems
Complete chaotic synchronization of end lasers has been observed in a line of
mutually coupled, time-delayed system of three lasers, with no direct
communication between the end lasers. The present paper uses ideas from
generalized synchronization to explain the complete synchronization in the
presence of long coupling delays, applied to a model of mutually coupled
semiconductor lasers in a line. These ideas significantly simplify the analysis
by casting the stability in terms of the local dynamics of each laser. The
variational equations near the synchronization manifold are analyzed, and used
to derive the synchronization condition that is a function of the parameters.
The results explain and predict the dependence of synchronization on various
parameters, such as time-delays, strength of coupling and dissipation. The
ideas can be applied to understand complete synchronization in other chaotic
systems with coupling delays and no direct communication between synchronized
sub-systems.Comment: 22 pages, 6 figure
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