12,311 research outputs found
Bulk effects on topological conduction on the surface of 3-D topological insulators
The surface states of a topological insulator in a fine-tuned magnetic field
are ideal candidates for realizing a topological metal which is protected
against disorder. Its signatures are (1) a conductance plateau in long wires in
a finely tuned longitudinal magnetic field and (2) a conductivity which always
increases with sample size, and both are independent of disorder strength. We
numerically study how these experimental transport signatures are affected by
bulk physics in the interior of the topological insulator sample. We show that
both signatures of the topological metal are robust against bulk effects.
However the bulk does substantially accelerate the metal's decay in a magnetic
field and alter its response to surface disorder. When the disorder strength is
tuned to resonance with the bulk band the conductivity follows the predictions
of scaling theory, indicating that conduction is diffusive. At other disorder
strengths the bulk reduces the effects of surface disorder and scaling theory
is systematically violated, signaling that conduction is not fully diffusive.
These effects will change the magnitude of the surface conductivity and the
magnetoconductivity
On the Uniqueness of Global Multiple SLEs
This article focuses on the characterization of global multiple
Schramm-Loewner evolutions (SLE). The chordal SLE process describes the scaling
limit of a single interface in various critical lattice models with Dobrushin
boundary conditions, and similarly, global multiple SLEs describe scaling
limits of collections of interfaces in critical lattice models with alternating
boundary conditions. In this article, we give a minimal amount of
characterizing properties for the global multiple SLEs: we prove that there
exists a unique probability measure on collections of pairwise disjoint
continuous simple curves with a certain conditional law property. As a
consequence, we obtain the convergence of multiple interfaces in the critical
Ising and FK-Ising models.Comment: 30 pages, 4 figure
Asymptotic shallow water models for internal waves in a two-fluid system with a free surface
In this paper, we derive asymptotic models for the propagation of two and
three-dimensional gravity waves at the free surface and the interface between
two layers of immiscible fluids of different densities, over an uneven bottom.
We assume the thickness of the upper and lower fluids to be of comparable size,
and small compared to the characteristic wavelength of the system (shallow
water regimes). Following a method introduced by Bona, Lannes and Saut based on
the expansion of the involved Dirichlet-to-Neumann operators, we are able to
give a rigorous justification of classical models for weakly and strongly
nonlinear waves, as well as interesting new ones. In particular, we derive
linearly well-posed systems in the so called Boussinesq/Boussinesq regime.
Furthermore, we establish the consistency of the full Euler system with these
models, and deduce the convergence of the solutions.Comment: 32 pages, 4 figure
Flash Point Measurements and Modeling for Ternary Partially Miscible AqueousÂOrganic Mixtures
Flash point is the most important variable used to characterize the fire and explosion hazard of liquids. This paper presents the first partially miscible aqueousorganic mixtures flash point measurements and modeling for the ternary type-I mixtures, water + ethanol + 1-butanol, water + ethanol + 2-butanol, and the type-II mixture, water + 1-butanol + 2-butanol. Results reveal that the flash points are constant in each tie line. Handling the non-ideality of the liquid phase through the use of activity coefficient models, the general flash-point model of Liaw et al. extended to partially miscible mixtures predicts the experimental data well when using literature LLE and the VLE activity coefficient model binary parameters to estimate sequentially the span and flash point in each tie line and the flash point in the mutual solubility region, respectively. The constant flash-point behavior in a tie line is also observed and predicted, in agreement with the VLLE tie line property that a single vapor is in equilibrium with all liquid composition on a tie line. For the aqueousorganic mixtures here studied, a deviation between prediction and measurements is observed, arising from the failure of the constant lower flammable limit assumption in the mutual solubility inert-rich region. Potential application for the model concerns the assessment of fire and explosion hazards and the development of inherently safer designs for chemical processes containing partially miscible aqueousorganic mixtures
On Patchworks and Hierarchies
Motivated by questions in biological classification, we discuss some
elementary combinatorial and computational properties of certain set systems
that generalize hierarchies, namely, 'patchworks', 'weak patchworks', 'ample
patchworks' and 'saturated patchworks' and also outline how these concepts
relate to an apparently new 'duality theory' for cluster systems that is based
on the fundamental concept of 'compatibility' of clusters.Comment: 17 pages, 2 figure
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