48,683 research outputs found
The tensor structure on the representation category of the triplet algebra
We study the braided monoidal structure that the fusion product induces on
the abelian category -mod, the category of representations of
the triplet -algebra . The -algebras are a
family of vertex operator algebras that form the simplest known examples of
symmetry algebras of logarithmic conformal field theories. We formalise the
methods for computing fusion products, developed by Nahm, Gaberdiel and Kausch,
that are widely used in the physics literature and illustrate a systematic
approach to calculating fusion products in non-semi-simple representation
categories. We apply these methods to the braided monoidal structure of
-mod, previously constructed by Huang, Lepowsky and Zhang, to
prove that this braided monoidal structure is rigid. The rigidity of
-mod allows us to prove explicit formulae for the fusion product
on the set of all simple and all projective -modules, which were
first conjectured by Fuchs, Hwang, Semikhatov and Tipunin; and Gaberdiel and
Runkel.Comment: 58 pages; edit: added references and revisions according to referee
reports. Version to appear on J. Phys.
Microstructure control during twin roll casting of an AZ31 magnesium alloy
The existing twin roll casting technique for magnesium alloys suffers heterogeneity in both microstructure and chemistry and downstream processing is required to improve the strip quality, resulting in cost rise. In the present work, twin roll casting was carried out using an AZ31 magnesium alloy, with the application of intensive shearing melt conditioning prior to casting. The effect of process parameters such as pouring temperature and casting speed on microstructure control during casting and subsequent downstream processing was studied. Experimental results showed that the melt conditioning treatment allowed the production of AZ31 strips with uniform and refined microstructure free of centreline segregations. It was also shown that an optimized combination of pouring temperature and casting speed, in conjunction with a strip thickness control operation, resulted in uniformly distributed stored energies due to enhanced plastic deformation, which promoted recrystallization during casting and subsequent heat treatment. Strips prepared by twin roll casting and homogenization developed similar microstructural features to those prepared by twin roll casting followed by lengthy downstream processing by homogenization, hot rolling and annealing and displayed a weaker basal texture, exhibiting a potentially better formability.The EPSRC (UK
The Radon transform and its dual for limits of symmetric spaces
The Radon transform and its dual are central objects in geometric analysis on
Riemannian symmetric spaces of the noncompact type. In this article we study
algebraic versions of those transforms on inductive limits of symmetric spaces.
In particular, we show that normalized versions exists on some spaces of
regular functions on the limit. We give a formula for the normalized transform
using integral kernels and relate them to limits of double fibration transforms
on spheres
Full Hydrodynamic Model of Nonlinear Electromagnetic Response in Metallic Metamaterials
Applications of metallic metamaterials have generated significant interest in
recent years. Electromagnetic behavior of metamaterials in the optical range is
usually characterized by a local-linear response. In this article, we develop a
finite-difference time-domain (FDTD) solution of the hydrodynamic model that
describes a free electron gas in metals. Extending beyond the local-linear
response, the hydrodynamic model enables numerical investigation of nonlocal
and nonlinear interactions between electromagnetic waves and metallic
metamaterials. By explicitly imposing the current continuity constraint, the
proposed model is solved in a self-consistent manner. Charge, energy and
angular momentum conservation laws of high-order harmonic generation have been
demonstrated for the first time by the Maxwell-hydrodynamic FDTD model. The
model yields nonlinear optical responses for complex metallic metamaterials
irradiated by a variety of waveforms. Consequently, the multiphysics model
opens up unique opportunities for characterizing and designing nonlinear
nanodevices.Comment: 11 pages, 14 figure
Dual function additives: A small molecule crosslinker for enhanced efficiency and stability in organic solar cells
A bis‐azide‐based small molecule crosslinker is synthesized and evaluated as both a stabilizing and efficiency‐boosting additive in bulk heterojunction organic photovoltaic cells. Activated by a noninvasive and scalable solution processing technique, polymer:fullerene blends exhibit improved thermal stability with suppressed polymer skin formation at the cathode and frustrated fullerene aggregation on ageing, with initial efficiency increased from 6% to 7%
The mechanics of inelastic buckling using a Shanley-like model
This paper presents a study of the mechanics of inelastic buckling using a Shanley-like simplified column model. The model is an extension of the original Shanley model with multiple springs and two dampers. The inclusion of damping enables the dynamic response of the model under constant loading to be captured. The model has been evaluated against the tangent-modulus and reduced-modulus critical buckling loads, and has been found effective in representing the progressive change in the regions of loading and unloading during inelastic buckling. It is also able to simulate the extreme situations of inelastic buckling by varying the ratio of the two damping coefficients. It is seen that high rotational damping, relative to vertical damping, causes the buckling to move towards the reducedmodulus buckling load at much lower deflections than when the relationship is reversed
Meromorphic open-string vertex algebras
A notion of meromorphic open-string vertex algebra is introduced. A
meromorphic open-string vertex algebra is an open-string vertex algebra in the
sense of Kong and the author satisfying additional rationality (or
meromorphicity) conditions for vertex operators. The vertex operator map for a
meromorphic open-string vertex algebra satisfies rationality and associativity
but in general does not satisfy the Jacobi identity, commutativity, the
commutator formula, the skew-symmetry or even the associator formula. Given a
vector space \mathfrak{h}, we construct a meromorphic open-string vertex
algebra structure on the tensor algebra of the negative part of the
affinization of \mathfrak{h} such that the vertex algebra struture on the
symmetric algebra of the negative part of the Heisenberg algebra associated to
\mathfrak{h} is a quotient of this meromorphic open-string vertex algebra. We
also introduce the notion of left module for a meromorphic open-string vertex
algebra and construct left modules for the meromorphic open-string vertex
algebra above.Comment: 43 pape
The application of the global isomorphism to the surface tension of the liquid-vapor interface of the Lennard-Jones fluids
In this communication we show that the surface tension of the real fluids of
the Lennard-Jones type can be obtained from the surface tension of the lattice
gas (Ising model) on the basis of the global isomorphism approach developed
earlier for the bulk properties.Comment: 8 pages, 6 figure
- …