4,177 research outputs found
Energy Management for a User Interactive Smart Community: A Stackelberg Game Approach
This paper studies a three party energy management problem in a user
interactive smart community that consists of a large number of residential
units (RUs) with distributed energy resources (DERs), a shared facility
controller (SFC) and the main grid. A Stackelberg game is formulated to benefit
both the SFC and RUs, in terms of incurred cost and achieved utility
respectively, from their energy trading with each other and the grid. The
properties of the game are studied and it is shown that there exists a unique
Stackelberg equilibrium (SE). A novel algorithm is proposed that can be
implemented in a distributed fashion by both RUs and the SFC to reach the SE.
The convergence of the algorithm is also proven, and shown to always reach the
SE. Numerical examples are used to assess the properties and effectiveness of
the proposed scheme.Comment: 6 pages, 4 figure
Feasibility of Using Discriminate Pricing Schemes for Energy Trading in Smart Grid
This paper investigates the feasibility of using a discriminate pricing
scheme to offset the inconvenience that is experienced by an energy user (EU)
in trading its energy with an energy controller in smart grid. The main
objective is to encourage EUs with small distributed energy resources (DERs),
or with high sensitivity to their inconvenience, to take part in the energy
trading via providing incentive to them with relatively higher payment at the
same time as reducing the total cost to the energy controller. The proposed
scheme is modeled through a two-stage Stackelberg game that describes the
energy trading between a shared facility authority (SFA) and EUs in a smart
community. A suitable cost function is proposed for the SFA to leverage the
generation of discriminate pricing according to the inconvenience experienced
by each EU. It is shown that the game has a unique sub-game perfect equilibrium
(SPE), under the certain condition at which the SFA's total cost is minimized,
and that each EU receives its best utility according to its associated
inconvenience for the given price. A backward induction technique is used to
derive a closed form expression for the price function at SPE, and thus the
dependency of price on an EU's different decision parameters is explained for
the studied system. Numerical examples are provided to show the beneficial
properties of the proposed scheme.Comment: 7 pages, 4 figures, 3 tables, conference pape
High temperature cavity polaritons in epitaxial Er_2O_3 on silicon
Cavity polaritons around two Er^(3+) optical transitions are observed in microdisk resonators fabricated from epitaxial Er_2O_3 on Si(111). Using a pump-probe method, spectral anticrossings and linewidth averaging of the polariton modes are measured in the cavity transmission and luminescence at temperatures above 361 K
Changes in Polarization Position Angle across the Eclipse in the Double Pulsar System
We investigate the changes in polarization position angle in radiation from
pulsar A around the eclipse in the Double Pulsar system PSR J0737-3039A/B at
the 20 cm and 50 cm wavelengths using the Parkes 64-m telescope. The changes
are ~2\sigma\ during and shortly after the eclipse at 20 cm but less
significant at 50 cm. We show that the changes in position angle during the
eclipse can be modelled by differential synchrotron absorption in the eclipse
regions. Position angle changes after the eclipse are interpreted as Faraday
rotation in the magnetotail of pulsar B. Implied charge densities are
consistent with the Goldreich-Julian density, suggesting that the particle
energies in the magnetotail are mildly relativistic.Comment: Accepted for publication in The Astrophysical Journal Letter
Unambiguous state discrimination in quantum cryptography with weak coherent states
The use of linearly independent signal states in realistic implementations of
quantum key distribution (QKD) enables an eavesdropper to perform unambiguous
state discrimination. We explore quantitatively the limits for secure QKD
imposed by this fact taking into account that the receiver can monitor to some
extend the photon number statistics of the signals even with todays standard
detection schemes. We compare our attack to the beamsplitting attack and show
that security against beamsplitting attack does not necessarily imply security
against the attack considered here.Comment: 10 pages, 6 figures, updated version with added discussion of
beamsplitting attac
Instruments and channels in quantum information theory
While a positive operator valued measure gives the probabilities in a quantum
measurement, an instrument gives both the probabilities and the a posteriori
states. By interpreting the instrument as a quantum channel and by using the
typical inequalities for the quantum and classical relative entropies, many
bounds on the classical information extracted in a quantum measurement, of the
type of Holevo's bound, are obtained in a unified manner.Comment: 12 pages, revtex
Estimates for practical quantum cryptography
In this article I present a protocol for quantum cryptography which is secure
against attacks on individual signals. It is based on the Bennett-Brassard
protocol of 1984 (BB84). The security proof is complete as far as the use of
single photons as signal states is concerned. Emphasis is given to the
practicability of the resulting protocol. For each run of the quantum key
distribution the security statement gives the probability of a successful key
generation and the probability for an eavesdropper's knowledge, measured as
change in Shannon entropy, to be below a specified maximal value.Comment: Authentication scheme corrected. Other improvements of presentatio
Operational Theory of Homodyne Detection
We discuss a balanced homodyne detection scheme with imperfect detectors in
the framework of the operational approach to quantum measurement. We show that
a realistic homodyne measurement is described by a family of operational
observables that depends on the experimental setup, rather than a single field
quadrature operator. We find an explicit form of this family, which fully
characterizes the experimental device and is independent of a specific state of
the measured system. We also derive operational homodyne observables for the
setup with a random phase, which has been recently applied in an ultrafast
measurement of the photon statistics of a pulsed diode laser. The operational
formulation directly gives the relation between the detected noise and the
intrinsic quantum fluctuations of the measured field. We demonstrate this on
two examples: the operational uncertainty relation for the field quadratures,
and the homodyne detection of suppressed fluctuations in photon statistics.Comment: 7 pages, REVTe
Growth, processing, and optical properties of epitaxial Er_2O_3 on silicon
Erbium-doped materials have been investigated for generating and amplifying light in low-power chip-scale optical networks on silicon, but several effects limit their performance in dense microphotonic applications. Stoichiometric ionic crystals are a potential alternative that achieve an Er^(3+) density 100× greater. We report the growth, processing, material characterization, and optical properties of single-crystal Er_2O_3 epitaxially grown on silicon. A peak Er^(3+) resonant absorption of 364 dB/cm at 1535nm with minimal background loss places a high limit on potential gain. Using high-quality microdisk resonators, we conduct thorough C/L-band radiative efficiency and lifetime measurements and observe strong upconverted luminescence near 550 and 670 nm
Squeezing enhancement by damping in a driven atom-cavity system
In a driven atom-cavity coupled system in which the two-level atom is driven
by a classical field, the cavity mode which should be in a coherent state in
the absence of its reservoir, can be squeezed by coupling to its reservoir. The
squeezing effect is enhanced as the damping rate of the cavity is increased to
some extent.Comment: 3 pages and 3 figure
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