7,188 research outputs found
Agglomerative Magnets and Informal Regulatory Networks: Electricity Market Design Convergence in the USA and Continental Europe
The absence of one broadly accepted design template for liberalised electricity markets induces regulatory competition and institutional diversity. Focussing on continental Europe and the USA, this analysis explores how agents and structures accelerate or impede the move to one standard market design in the electricity sector. It reveals that market design convergence in Europe is driven by the 'Florence Consensus,' a tripartite coalition between the European Commission fostering European integration and the internal market, informal regulatory networks between grid operators, standardisation authorities and regulators, who have been coordinating their actions in the 'Florence Forum,' and epistemic communities exemplified in the Florence School of Regulation. In contrast, the United States' Federal Energy Regulatory Commission lacks support among politicians, many states' public utility commissions, the neo-liberal intelligentsia and even industrial lobbying groups to effectively push for a standardised market design. However, design convergence in the USA may be induced by the gradual expansion of multi-state markets operated by regional transmission organisations.Electricity, Deregulation, Regulatory Competition, Policy Diffusion
Lifetime of the surface magnetoplasmons in metallic nanoparticles
We study the influence of an external magnetic field on the collective
electronic excitations in metallic nanoparticles. While the usual surface
plasmon corresponding to the collective oscillation of the electrons with
respect to the ionic background persists in the direction parallel to the
magnetic field, the components in the perpendicular plane are affected by the
field and give rise to two collective modes with field-dependent frequencies,
the surface magnetoplasmons. We analyze the decay of these collective
excitations by their coupling to particle-hole excitations and determine how
their lifetimes are modified by the magnetic field. In particular, we show that
the lifetime of the usual surface plasmon is not modified by the magnetic
field, while the lifetime of the two surface magnetoplasmons present a weak
magnetic-field dependence. Optical spectroscopy experiments are suggested in
which signatures of the surface magnetoplasmons may be observed.Comment: 11 pages, 6 figures; published versio
Inpainting of Cyclic Data using First and Second Order Differences
Cyclic data arise in various image and signal processing applications such as
interferometric synthetic aperture radar, electroencephalogram data analysis,
and color image restoration in HSV or LCh spaces. In this paper we introduce a
variational inpainting model for cyclic data which utilizes our definition of
absolute cyclic second order differences. Based on analytical expressions for
the proximal mappings of these differences we propose a cyclic proximal point
algorithm (CPPA) for minimizing the corresponding functional. We choose
appropriate cycles to implement this algorithm in an efficient way. We further
introduce a simple strategy to initialize the unknown inpainting region.
Numerical results both for synthetic and real-world data demonstrate the
performance of our algorithm.Comment: accepted Converence Paper at EMMCVPR'1
A Second Order TV-type Approach for Inpainting and Denoising Higher Dimensional Combined Cyclic and Vector Space Data
In this paper we consider denoising and inpainting problems for higher
dimensional combined cyclic and linear space valued data. These kind of data
appear when dealing with nonlinear color spaces such as HSV, and they can be
obtained by changing the space domain of, e.g., an optical flow field to polar
coordinates. For such nonlinear data spaces, we develop algorithms for the
solution of the corresponding second order total variation (TV) type problems
for denoising, inpainting as well as the combination of both. We provide a
convergence analysis and we apply the algorithms to concrete problems.Comment: revised submitted versio
Two interacting particles in a disordered chain IV: Scaling of level curvatures
The curvatures of two-particle energy levels with respect to the enclosed
magnetic flux in mesoscopic disordered rings are investigated numerically. We
find that the typical value of the curvatures is increased by interactions in
the localised regime and decreased in the metallic regime. This confirms a
prediction by Akkermans and Pichard (Eur. Phys. J. B 1, 223 (1998)). The
interaction-induced changes of the typical curvatures at different energies and
disorder strengths exhibit one-parameter scaling with a conductance-like single
parameter. This suggests that interactions could influence the conductance of
mesoscopic systems similarly.Comment: 9 pages, 7 figures. Other parts of the series: cond-mat/9706258,
cond-mat/9801134, cond-mat/980813
Delocalization due to correlations in two-dimensional disordered systems
We study the spectral statistics of interacting spinless fermions in a
two-dimensional disordered lattice. Within a full quantum treatment for small
few-particle-systems, we compute the low-energy many-body states numerically.
While at weak disorder the interactions reduce spectral correlations and lead
to localization, for the case of strong disorder we find that a moderate
Coulomb interaction has a delocalizing effect. In addition, we observe a
non-universal structure in the level-spacing distribution which we attribute to
a mechanism reinforcing spectral correlations taking place in small systems at
strong disorder.Comment: 6 pages, 4 figures, corrected typo
Persistent currents for Coulomb interacting electrons on 2d disordered lattices: Sign and interaction dependence in the Wigner crystal regime
A Wigner crystal structure of the electronic ground state is induced by
strong Coulomb interactions at low temperature in clean or disordered
two-dimensional (2d) samples. For fermions on a mesoscopic disordered 2d
lattice, being closed to a torus, we study the persistent current in the regime
of strong interaction at zero temperature. We perform a perturbation expansion
starting from the Wigner crystal limit which yields power laws for the
dependence of the persistent current on the interaction strength. The sign of
the persistent current in the strong interaction limit is independent of the
disorder realization and strength. It depends only on the electro-statically
determined configuration of the particles in the Wigner crystal.Comment: 13 pages, 4 figures, final version (introduction and discussion
extended
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