55,138 research outputs found
Model Predictive BESS Control for Demand Charge Management and PV-Utilization Improvement
Adoption of battery energy storage systems for behind-the-meters application
offers valuable benefits for demand charge management as well as increasing
PV-utilization. The key point is that while the benefit/cost ratio for a single
application may not be favorable for economic benefits of storage systems,
stacked services can provide multiple revenue streams for the same investment.
Under this framework, we propose a model predictive controller to reduce demand
charge cost and enhance PV-utilization level simultaneously. Different load
patterns have been considered in this study and results are compared to the
conventional rule-based controller. The results verified that the proposed
controller provides satisfactory performance by improving the PV-utilization
rate between 60% to 80% without significant changes in demand charge (DC)
saving. Furthermore, our results suggest that batteries can be used for
stacking multiple services to improve their benefits. Quantitative analysis for
PV-utilization as a function of battery size and prediction time window has
also been carried out.Comment: Accepted in: Conference on Innovative Smart Grid Technology (ISGT),
Washington, DC, 201
On the design of optimal compliant walls for turbulence control
This paper employs the theoretical framework developed by Luhar et al. (J.
Fluid Mech., 768, 415-441) to consider the design of compliant walls for
turbulent skin friction reduction. Specifically, the effects of simple
spring-damper walls are contrasted with the effects of more complex walls
incorporating tension, stiffness and anisotropy. In addition, varying mass
ratios are tested to provide insight into differences between aerodynamic and
hydrodynamic applications. Despite the differing physical responses, all the
walls tested exhibit some important common features. First, the effect of the
walls (positive or negative) is greatest at conditions close to resonance, with
sharp transitions in performance across the resonant frequency or phase speed.
Second, compliant walls are predicted to have a more pronounced effect on
slower-moving structures because such structures generally have larger
wall-pressure signatures. Third, two-dimensional (spanwise constant) structures
are particularly susceptible to further amplification. These features are
consistent with many previous experiments and simulations, suggesting that
mitigating the rise of such two-dimensional structures is essential to
designing performance-improving walls. For instance, it is shown that further
amplification of such large-scale two-dimensional structures explains why the
optimal anisotropic walls identified by Fukagata et al. via DNS (J. Turb., 9,
1-17) only led to drag reduction in very small domains. The above observations
are used to develop design and methodology guidelines for future research on
compliant walls
Bound State Solutions of Klein-Gordon Equation with the Kratzer Potential
The relativistic problem of spinless particle subject to a Kratzer potential
is analyzed. Bound state solutions for the s-wave are found by separating the
Klein-Gordon equation in two parts, unlike the similar works in the literature,
which provides one to see explicitly the relativistic contributions, if any, to
the solution in the non-relativistic limit.Comment: 6 page
Unified equation of state for neutron stars on a microscopic basis
We derive a new equation of state (EoS) for neutron stars (NS) from the outer
crust to the core based on modern microscopic Brueckner-Hartree-Fock (BHF)
calculations using the Argonne potential plus three-body forces
computed with the Urbana model. To deal with the inhomogeneous structures of
matter in the NS crust, we use the recent Barcelona-Catania-Paris-Madrid (BCPM)
nuclear energy density functional that is directly based on the same
microscopic BHF calculations, and which is able to reproduce the ground-state
properties of nuclei along the periodic table. The EoS of the outer crust
requires the masses of neutron-rich nuclei, which are obtained through
Hartree-Fock-Bogoliubov calculations with the BCPM functional when they are
unknown experimentally. To compute the inner crust, Thomas-Fermi calculations
in Wigner-Seitz cells are performed with the same functional. Existence of
nuclear pasta is predicted in a range of average baryon densities between
0.067 fm and 0.0825 fm, where the transition to
the core takes place. The NS core is computed from the nuclear EoS of the BHF
calculation assuming non-exotic constituents (core of matter). In each
region of the star, we discuss the comparison of the new EoS with previous
EoSes for the complete NS structure, in particular, with the Lattimer-Swesty
EoS and with the Shen et al. EoS widely used in astrophysical calculations. The
new microscopically derived EoS fulfills at the same time a NS maximum mass of
2~ with a radius of 10 km, and a 1.5~ NS with a radius of
11.7 km.Comment: 23 pages, 17 figures, revised version accepted for publication in
Astronomy & Astrophysic
Nuclear Breathing Mode in the Relativistic Mean Field Theory
The breathing-mode giant monopole resonance is studied within the framework
of the relativistic mean-field (RMF) theory. Using a broad range of parameter
sets, an analysis of constrained incompressibility and excitation energy of
isoscalar monopole states in finite nuclei is performed. It is shown that the
non-linear scalar self-interaction and the resulting surface properties
influence the breathing-mode considerably. It is observed that dynamical
surface properties respond differently in the RMF theory than in the Skyrme
approach. A comparison is made with the incompressibility derived from the
semi-infinite nuclear matter and with constrained nonrelativistic Skyrme
Hartree-Fock calculaions.Comment: Latex (12 pages) and 3 figures (available upon request) J. Phys. G
(in press
Isospin Dependence of the Spin-Orbit Force and Effective Nuclear Potentials,
The isospin dependence of the spin-orbit potential is investigated for an
effective Skyrme-like energy functional suitable for density dependent
Hartree-Fock calculations. The magnitude of the isospin dependence is obtained
from a fit to experimental data on finite spherical nuclei. It is found to be
close to that of relativistic Hartree models. Consequently, the anomalous kink
in the isotope shifts of Pb nuclei is well reproduced.Comment: Revised, 11 pages (Revtex) and 2 figures available upon request,
Preprint MPA-833, Physical Review Letters (in press)
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