The Models of Strategic Interaction between Network and Generating Companies at Electricity Transmission Market

The paper considers the strategic interaction between network and generating companies at electricity transmission market within the simplest electric power system with two nodes. The four possible variants of the market organization are investigated: guaranteed regulated and non-regulated network monopoly, network monopoly facing potential competition from the independent network company or generating company. The possible consequences and by-effects of vertical unbundling, in particular, influence of such a regulation on the prices and network transfer capabilities, are analyzed. It is shown that the elimination of monopolistic preferences on electric power transmission with the possibility of network objects building and operation by the generating companies is an effective mechanism for electricity price reduction.oligopoly, monopoly, strategic interaction, potential competition, Nash equilibrium, electricity transmission market

Controlling circular polarization of light emitted by quantum dots using chiral photonic crystal slab

We study the polarization properties of light emitted by quantum dots that are embedded in chiral photonic crystal structures made of achiral planar GaAs waveguides. A modification of the electromagnetic mode structure due to the chiral grating fabricated by partial etching of the wave\-guide layer has been shown to result in a high circular polarization degree $\rho_c$ of the quantum dot emission in the absence of external magnetic field. The physical nature of the phenomenon can be understood in terms of the reciprocity principle taking into account the structural symmetry. At the resonance wavelength, the magnitude of $|\rho_c|$ is predicted to exceed 98%. The experimentally achieved value of $|\rho_c|=81$% is smaller, which is due to the contribution of unpolarized light scattered by grating defects, thus breaking its periodicity. The achieved polarization degree estimated removing the unpolarized nonresonant background from the emission spectra can be estimated to be as high as 96%, close to the theoretical prediction

Electronic structure and magnetic properties of the spin-1/2 Heisenberg system CuSe2O5

A microscopic magnetic model for the spin-1/2 Heisenberg chain compound CuSe2O5 is developed based on the results of a joint experimental and theoretical study. Magnetic susceptibility and specific heat data give evidence for quasi-1D magnetism with leading antiferromagnetic (AFM) couplings and an AFM ordering temperature of 17 K. For microscopic insight, full-potential DFT calculations within the local density approximation (LDA) were performed. Using the resulting band structure, a consistent set of transfer integrals for an effective one-band tight-binding model was obtained. Electronic correlations were treated on a mean-field level starting from LDA (LSDA+U method) and on a model level (Hubbard model). In excellent agreement of experiment and theory, we find that only two couplings in CuSe2O5 are relevant: the nearest-neighbour intra-chain interaction of 165 K and a non-frustrated inter-chain coupling of 20 K. From a comparison with structurally related systems (Sr2Cu(PO4)2, Bi2CuO4), general implications for a magnetic ordering in presence of inter-chain frustration are made.Comment: 20 pages, 8 figures, 3 table