3,687 research outputs found
Load Shifting in the Smart Grid: To Participate or Not?
Demand-side management (DSM) has emerged as an important smart grid feature
that allows utility companies to maintain desirable grid loads. However, the
success of DSM is contingent on active customer participation. Indeed, most
existing DSM studies are based on game-theoretic models that assume customers
will act rationally and will voluntarily participate in DSM. In contrast, in
this paper, the impact of customers' subjective behavior on each other's DSM
decisions is explicitly accounted for. In particular, a noncooperative game is
formulated between grid customers in which each customer can decide on whether
to participate in DSM or not. In this game, customers seek to minimize a cost
function that reflects their total payment for electricity. Unlike classical
game-theoretic DSM studies which assume that customers are rational in their
decision-making, a novel approach is proposed, based on the framework of
prospect theory (PT), to explicitly incorporate the impact of customer behavior
on DSM decisions. To solve the proposed game under both conventional game
theory and PT, a new algorithm based on fictitious player is proposed using
which the game will reach an epsilon-mixed Nash equilibrium. Simulation results
assess the impact of customer behavior on demand-side management. In
particular, the overall participation level and grid load can depend
significantly on the rationality level of the players and their risk aversion
tendency.Comment: 9 pages, 7 figures, journal, accepte
Integrating Energy Storage into the Smart Grid: A Prospect Theoretic Approach
In this paper, the interactions and energy exchange decisions of a number of
geographically distributed storage units are studied under decision-making
involving end-users. In particular, a noncooperative game is formulated between
customer-owned storage units where each storage unit's owner can decide on
whether to charge or discharge energy with a given probability so as to
maximize a utility that reflects the tradeoff between the monetary transactions
from charging/discharging and the penalty from power regulation. Unlike
existing game-theoretic works which assume that players make their decisions
rationally and objectively, we use the new framework of prospect theory (PT) to
explicitly incorporate the users' subjective perceptions of their expected
utilities. For the two-player game, we show the existence of a proper mixed
Nash equilibrium for both the standard game-theoretic case and the case with PT
considerations. Simulation results show that incorporating user behavior via PT
reveals several important insights into load management as well as economics of
energy storage usage. For instance, the results show that deviations from
conventional game theory, as predicted by PT, can lead to undesirable grid
loads and revenues thus requiring the power company to revisit its pricing
schemes and the customers to reassess their energy storage usage choices.Comment: 5 pages, 4 figures, conferenc
Casimir potential of a compact object enclosed by a spherical cavity
We study the electromagnetic Casimir interaction of a compact object
contained inside a closed cavity of another compact object. We express the
interaction energy in terms of the objects' scattering matrices and translation
matrices that relate the coordinate systems appropriate to each object. When
the enclosing object is an otherwise empty metallic spherical shell, much
larger than the internal object, and the two are sufficiently separated, the
Casimir force can be expressed in terms of the static electric and magnetic
multipole polarizabilities of the internal object, which is analogous to the
Casimir-Polder result. Although it is not a simple power law, the dependence of
the force on the separation of the object from the containing sphere is a
universal function of its displacement from the center of the sphere,
independent of other details of the object's electromagnetic response.
Furthermore, we compute the exact Casimir force between two metallic spheres
contained one inside the other at arbitrary separations. Finally, we combine
our results with earlier work on the Casimir force between two spheres to
obtain data on the leading order correction to the Proximity Force
Approximation for two metallic spheres both outside and within one another.Comment: 12 pages, 6 figure
Casimir interactions of an object inside a spherical metal shell
We investigate the electromagnetic Casimir interactions of an object
contained within an otherwise empty, perfectly conducting spherical shell. For
a small object we present analytical calculations of the force, which is
directed away from the center of the cavity, and the torque, which tends to
align the object opposite to the preferred alignment outside the cavity. For a
perfectly conducting sphere as the interior object, we compute the corrections
to the proximity force approximation (PFA) numerically. In both cases the
results for the interior configuration match smoothly onto those for the
corresponding exterior configuration.Comment: 4 pages, 3 figure
A numerical study of two-photon ionization of helium using the Pyprop framework
Few-photon induced breakup of helium is studied using a newly developed ab
initio numerical framework for solving the six-dimensional time-dependent
Schroedinger equation. We present details of the method and calculate
(generalized) cross sections for the process of two-photon nonsequential
(direct) double ionization at photon energies ranging from 39.4 to 54.4 eV, a
process that has been very much debated in recent years and is not yet fully
understood. In particular, we have studied the convergence property of the
total cross section in the vicinity of the upper threshold (54.4 eV), versus
the pulse duration of the applied laser field. We find that the cross section
exhibits an increasing trend near the threshold, as has also been observed by
others, and show that this rise cannot solely be attributed to an unintended
inclusion of the sequential two-photon double ionization process, caused by the
bandwidth of the applied field.Comment: 7 pages, 3 figure
Solvable Systems of Linear Differential Equations
The asymptotic iteration method (AIM) is an iterative technique used to find
exact and approximate solutions to second-order linear differential equations.
In this work, we employed AIM to solve systems of two first-order linear
differential equations. The termination criteria of AIM will be re-examined and
the whole theory is re-worked in order to fit this new application. As a result
of our investigation, an interesting connection between the solution of linear
systems and the solution of Riccati equations is established. Further, new
classes of exactly solvable systems of linear differential equations with
variable coefficients are obtained. The method discussed allow to construct
many solvable classes through a simple procedure.Comment: 13 page
Levels of Glucose-6-phosphate Dehydrogenase in Type 1 Diabetes Mellitus patients with Nephropathy and Cardiovascular disease complication
The aim of this study is to evaluate oxidative stress in diabetes mellitus (DM) Type1 by the measurement of Glucose-6-phosphate Dehydrogenase (G-6-PD), an enzyme expressed in human RBCs, is important in the generation of reduced glutathione which is the key product in oxidative stress controls. The Study was carried on 80 samples of blood and serum of National Diabetes Center (NDC). The study groups under fasting conditions and they divided as:20 samples of diabetes mellitus patients without complications and 20 samples of diabetes mellitus with cardiovascular (CV) complications and 20 samples of diabetes mellitus with Nephropathy (Neph) complications compared with 20 control group with average age (13-67) years.. The results showed an elevation in the lipid profile and urea levels in patients groups compared with control group and a decrease in glucose-6-phosphate Dehydrogenase, HDL levels in all patients groups compared with control group
Economics of Electric Vehicle Charging: A Game Theoretic Approach
In this paper, the problem of grid-to-vehicle energy exchange between a smart
grid and plug-in electric vehicle groups (PEVGs) is studied using a
noncooperative Stackelberg game. In this game, on the one hand, the smart grid
that acts as a leader, needs to decide on its price so as to optimize its
revenue while ensuring the PEVGs' participation. On the other hand, the PEVGs,
which act as followers, need to decide on their charging strategies so as to
optimize a tradeoff between the benefit from battery charging and the
associated cost. Using variational inequalities, it is shown that the proposed
game possesses a socially optimal Stackelberg equilibrium in which the grid
optimizes its price while the PEVGs choose their equilibrium strategies. A
distributed algorithm that enables the PEVGs and the smart grid to reach this
equilibrium is proposed and assessed by extensive simulations. Further, the
model is extended to a time-varying case that can incorporate and handle slowly
varying environments
Transfer Learning with Deep Convolutional Neural Network (CNN) for Pneumonia Detection using Chest X-ray
Pneumonia is a life-threatening disease, which occurs in the lungs caused by
either bacterial or viral infection. It can be life-endangering if not acted
upon in the right time and thus an early diagnosis of pneumonia is vital. The
aim of this paper is to automatically detect bacterial and viral pneumonia
using digital x-ray images. It provides a detailed report on advances made in
making accurate detection of pneumonia and then presents the methodology
adopted by the authors. Four different pre-trained deep Convolutional Neural
Network (CNN)- AlexNet, ResNet18, DenseNet201, and SqueezeNet were used for
transfer learning. 5247 Bacterial, viral and normal chest x-rays images
underwent preprocessing techniques and the modified images were trained for the
transfer learning based classification task. In this work, the authors have
reported three schemes of classifications: normal vs pneumonia, bacterial vs
viral pneumonia and normal, bacterial and viral pneumonia. The classification
accuracy of normal and pneumonia images, bacterial and viral pneumonia images,
and normal, bacterial and viral pneumonia were 98%, 95%, and 93.3%
respectively. This is the highest accuracy in any scheme than the accuracies
reported in the literature. Therefore, the proposed study can be useful in
faster-diagnosing pneumonia by the radiologist and can help in the fast airport
screening of pneumonia patients.Comment: 13 Figures, 5 tables. arXiv admin note: text overlap with
arXiv:2003.1314
Energies and wave functions for a soft-core Coulomb potential
For the family of model soft Coulomb potentials represented by V(r) =
-\frac{Z}{(r^q+\beta^q)^{\frac{1}{q}}}, with the parameters
Z>0, \beta>0, q \ge 1, it is shown analytically that the potentials and
eigenvalues, E_{\nu\ell}, are monotonic in each parameter. The potential
envelope method is applied to obtain approximate analytic estimates in terms of
the known exact spectra for pure power potentials. For the case q =1, the
Asymptotic Iteration Method is used to find exact analytic results for the
eigenvalues E_{\nu\ell} and corresponding wave functions, expressed in terms of
Z and \beta. A proof is presented establishing the general concavity of the
scaled electron density near the nucleus resulting from the truncated
potentials for all q. Based on an analysis of extensive numerical calculations,
it is conjectured that the crossing between the pair of states
[(\nu,\ell),(\nu',\ell')], is given by the condition \nu'\geq (\nu+1) and \ell'
\geq (\ell+3). The significance of these results for the interaction of an
intense laser field with an atom is pointed out. Differences in the observed
level-crossing effects between the soft potentials and the hydrogen atom
confined inside an impenetrable sphere are discussed.Comment: 13 pages, 5 figures, title change, minor revision
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