56,936 research outputs found
Complete light absorption in graphene-metamaterial corrugated structures
We show that surface-plasmon polaritons excited in negative permittivity
metamaterials having shallow periodic surface corrugation profiles can be
explored to push the absorption of single and continuous sheets of graphene up
to 100%. In the relaxation regime, the position of the plasmonic resonances of
the hybrid system is determined by the plasma frequency of the metamaterial,
allowing the frequency range for enhanced absorption to be set without the need
of engineering graphene.Comment: 6 pages, 4 figures; published version: text revised and references
adde
A novel framework for the use of workflow system in the integration of supply chain tiers
The global competition has imposed challenges to supply chain integration, mainly, during the process of obtain information to make demand management decisions. This paper proposes an integrated framework for data collection, analysis and results dissemination in the supply chain management (SCM), contributing to research and alternatives for \u201cThe Bullwhip Effect\u201d issue. In this sense, it is necessary to discuss the integration of supply chain management, Enterprise Resources Planning (ERP) functionality and others systems, to enlarge this scope to the total supply chain players. The ERP web-based tool and Workflow Systems (WS) can contribute to solve issues related to supply chain management. Starting from a detailed analysis of the research background regarding current SCM definitions and integration problems, Information Technology and Communication (ITC) development and WS in order to map and ensure flow fluency; the paper proposes a model to increase the overall integrations and an application in a case study for supporting the decisions that are aligned with the company\u2019s strategic objectives. This paper is divided in: research background; proposed model of the SC integration; case study, conclusions and future research
Exchange coupling between magnetic layers across non-magnetic superlattices
The oscillation periods of the interlayer exchange coupling are investigated
when two magnetic layers are separated by a metallic superlattice of two
distinct non-magnetic materials. In spite of the conventional behaviour of the
coupling as a function of the spacer thickness, new periods arise when the
coupling is looked upon as a function of the number of cells of the
superlattice. The new periodicity results from the deformation of the
corresponding Fermi surface, which is explicitly related to a few controllable
parameters, allowing the oscillation periods to be tuned.Comment: 13 pages; 5 figures; To appear in J. Phys.: Cond. Matte
Mass for Plasma Photons from Gauge Symmetry Breaking
We derive the effective masses for photons in unmagnetized plasma waves using
a quantum field theory with two vector fields (gauge fields). In order to
properly define the quantum field degrees of freedom we re-derive the classical
wave equations on light-front gauge. This is needed because the usual scalar
potential of electromagnetism is, in quantum field theory, not a physical
degree of freedom that renders negative energy eigenstates. We also consider a
background local fluid metric that allows for a covariant treatment of the
problem. The different masses for the longitudinal (plasmon) and transverse
photons are in our framework due to the local fluid metric. We apply the
mechanism of mass generation by gauge symmetry breaking recently proposed by
the authors by giving a non-trivial vacuum-expectation-value to the second
vector field (gauge field). The Debye length is interpreted as an
effective compactification length and we compute an explicit solution for the
large gauge transformations that correspond to the specific mass eigenvalues
derived here. Using an usual quantum field theory canonical quantization we
obtain the usual results in the literature. Although none of these ingredients
are new to physicist, as far as the authors are aware it is the first time that
such constructions are applied to Plasma Physics. Also we give a physical
interpretation (and realization) for the second vector field in terms of the
plasma background in terms of known physical phenomena.
Addendum: It is given a short proof that equation (10) is wrong, therefore
equations (12-17) are meaningless. The remaining results are correct being
generic derivations for nonmagnetized plasmas derived in a covariant QFT
framework.Comment: v1: 1+6 pages v2: Several discussions rewritten; Abstract rewritten;
References added; v3: includes Addendu
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