375 research outputs found
Photo-induced reduction of graphene oxide coating on optical waveguide and consequent optical intermodulation
Increased absorption of transverse-magnetic (TM) - polarised light by a graphene-oxide (GO) coated polymer waveguide has been observed in the presence of transverse-electric (TE) - polarised light. The GO-coated waveguide exhibits very strong photo-absorption of TE-polarised light - and acts as a TM-pass waveguide polariser. The absorbed TE-polarised light causes a significant temperature increase in the GO film and induces thermal reduction of the GO, resulting in an increase in optical-frequency conductivity and consequently increased optical propagation loss. This behaviour in a GO-coated waveguide gives the action of an inverted optical switch/modulator. By varying the incident TE-polarised light power, a maximum modulation efficiency of 72% was measured, with application of an incident optical power level of 57 mW. The GO-coated waveguide was able to respond clearly to modulated TE-polarised light with a pulse duration of as little as 100 μs. In addition, no wavelength dependence was observed in the response of either the modulation (TE-polarised light) or the signal (TM-polarised light)
Optimal embedding parameters: A modelling paradigm
Reconstruction of a dynamical system from a time series requires the
selection of two parameters, the embedding dimension and the embedding
lag . Many competing criteria to select these parameters exist, and all
are heuristic. Within the context of modeling the evolution operator of the
underlying dynamical system, we show that one only need be concerned with the
product . We introduce an information theoretic criteria for the
optimal selection of the embedding window . For infinitely long
time series this method is equivalent to selecting the embedding lag that
minimises the nonlinear model prediction error. For short and noisy time series
we find that the results of this new algorithm are data dependent and superior
to estimation of embedding parameters with the standard techniques
Undecidable properties of self-affine sets and multi-tape automata
We study the decidability of the topological properties of some objects
coming from fractal geometry. We prove that having empty interior is
undecidable for the sets defined by two-dimensional graph-directed iterated
function systems. These results are obtained by studying a particular class of
self-affine sets associated with multi-tape automata. We first establish the
undecidability of some language-theoretical properties of such automata, which
then translate into undecidability results about their associated self-affine
sets.Comment: 10 pages, v2 includes some corrections to match the published versio
UNDERSTANDING THE DETERMINANTS OF BLOCKCHAIN ADOPTION IN SUPPLY CHAINS: AN EMPIRICAL STUDY IN CHINA
This study adopts affordance approach to understand how supply chain managers interpret the possible benefits that can be performed within blockchain-enabled supply chain applications. With a focus on governance efficiency improvement, the impacts of traceability and transparency affordance on uncertainty reduction were examined from the perspective of transaction cost theory in supply chain industry. Partial least squares – structural equation modelling (PLS-SEM) was used to analyze the data collected from 364 experienced supply chain managers in China. The results revealed that traceability affordance exerted significant impacts on environmental and trading partner uncertainty rather than transparency affordance, which in turn affected the adoption intention. This study contributes to the extant literature by embedding transaction cost in blockchain affordances. The findings are useful in guiding practitioners to improve blockchain system design for reducing uncertainties in supply chain environment, leading to a higher adoption rate of blockchain technology
Strongly Interacting Luttinger Liquid and Superconductivity in an Exactly Solvable Model
A new family of exactly solvable one dimensional models with a hard-core
repulsive potential is solved by the Bethe Ansatz for an arbitrary hard-core
radius. The exact ground state phase diagrams in a plane 'electron density -
on-site interaction' have been studied for several values of a hard-core
radius. It is shown that superconducting phase and strongly interacting
Luttinger liquid state are coexisted at a high electron density and unusually
high value of repulsive on-site Coulomb interaction.Comment: 4 pages, 2 figures, RevTe
Exact Solution of a One-Dimensional Multicomponent Lattice Gas with Hyperbolic Interaction
We present the exact solution to a one-dimensional multicomponent quantum
lattice model interacting by an exchange operator which falls off as the
inverse-sinh-square of the distance. This interaction contains a variable range
as a parameter, and can thus interpolate between the known solutions for the
nearest-neighbor chain, and the inverse-square chain. The energy,
susceptibility, charge stiffness and the dispersion relations for low-lying
excitations are explicitly calculated for the absolute ground state, as a
function of both the range of the interaction and the number of species of
fermions.Comment: 13 REVTeX pages + 5 uuencoded figures, UoU-003059
Adaptive feedforward and feedback control schemes for sliding mode controlled power converters
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