60,411 research outputs found
A Study of deuteron electromagnetic form factors with light-front approach
The electromagnetic form factors and low-energy observables of deuteron are
studied with the help of the light-front approach, where the deuteron is
regarded as a weekly bound state of a proton and a neutron. Both the and
wave interacting vertexes among deuteron, proton, and neutron are taken
into account. Moreover, the regularization functions are also introduced. In
our calculations, the vertex and the regularization functions are employed to
simulate the momentum distribution inside the deuteron. Our numerical results
show that the light-front approach can roughly reproduce the deuteron
electromagnetic form factors, like charge , magnetic , and quadrupole
, in the low region. The important role of the wave vertex on
is also addressed
Polarized GPDs and structure functions of meson
The meson polarized generalized parton distribution functions, its
structure functions and and its axial form factors are studied based on a light-front quark model for the first time.
Comparing our obtained moments of to lattice QCD calculation, we find
that our results are reasonably consistent to the Lattice predictions
Distributed Real-Time Power Balancing in Renewable-Integrated Power Grids with Storage and Flexible Loads
The large-scale integration of renewable generation directly affects the
reliability of power grids. We investigate the problem of power balancing in a
general renewable-integrated power grid with storage and flexible loads. We
consider a power grid that is supplied by one conventional generator (CG) and
multiple renewable generators (RGs) each co-located with storage,and is
connected with external markets. An aggregator operates the power grid to
maintain power balance between supply and demand. Aiming at minimizing the
long-term system cost, we first propose a real-time centralized power balancing
solution, taking into account the uncertainty of the renewable generation,
loads, and energy prices. We then provide a distributed implementation
algorithm, significantly reducing both computational burden and communication
overhead. We demonstrate that our proposed algorithm is asymptotically optimal
as the storage capacity increases and the CG ramping constraint loosens.
Moreover, the distributed implementation enjoys a fast convergence rate, and
enables each RG and the aggregator to make their own decisions. Simulation
shows that our proposed algorithm outperforms alternatives and can achieve
near-optimal performance for a wide range of storage capacity.Comment: To appear in IEEE Transactions on Smart Grid, 201
Real-Time Welfare-Maximizing Regulation Allocation in Dynamic Aggregator-EVs System
The concept of vehicle-to-grid (V2G) has gained recent interest as more and
more electric vehicles (EVs) are put to use. In this paper, we consider a
dynamic aggregator-EVs system, where an aggregator centrally coordinates a
large number of dynamic EVs to perform regulation service. We propose a
Welfare-Maximizing Regulation Allocation (WMRA) algorithm for the aggregator to
fairly allocate the regulation amount among its EVs. Compared to previous
works, WMRA accommodates a wide spectrum of vital system characteristics,
including dynamics of EV, limited EV battery size, EV battery degradation cost,
and the cost of using external energy sources for the aggregator. The algorithm
operates in real time and does not require any prior knowledge of the
statistical information of the system. Theoretically, we demonstrate that WMRA
is away from the optimum by O(1/V), where V is a controlling parameter
depending on EV's battery size. In addition, our simulation results indicate
that WMRA can substantially outperform a suboptimal greedy algorithm.Comment: 13 page
WENO interpolation-based and upwind-biased schemes with free-stream preservation
Based on the understandings regarding linear upwind schemes with flux
splitting to achieve free-stream preservation (Q. Li, etc. Commun. Comput.
Phys., 22 (2017) 64-94), a series of WENO interpolation-based and upwind-biased
nonlinear schemes are proposed in this study. By means of engagement of fluxes
on midpoints, the nonlinearity of schemes is introduced through WENO
interpolations, and upwind-biased features are acquired through the choice of
dependent grid stencil. Regarding the third- and fifth-order versions, schemes
with one and two midpoints are devised and carefully tested. With the
integration of the piecewise-polynomial mapping function methods (Q. Li, etc.
Commun. Comput. Phys. 18 (2015) 1417-1444), the proposed schemes are found to
achieve the designed orders and free-stream preservation property. In 1-D Sod
and Shu-Osher problems, all schemes succeed in yielding well predictions. In
2-D cases, the vortex preservation, supersonic inviscid flow around cylinder at
M=4, Riemann problem and Shock-vortex interaction problems are tested. In each
problem, two types of grids are employed, i.e. the uniformed/smooth grids and
the randomized/partially-randomized grids. On the latter, the shock wave and
complex flow structures are located/partially located. All schemes fulfill
computations in uniformed/smooth grids with satisfactory results. On randomized
grids, all schemes accomplish computations and yield reasonable results except
the third-order one with two midpoints engaged fails in Riemann problem and
shock-vortex interaction problem. Overall speaking, the proposed schemes
manifest the capability to solve problems on grids with bad quality, and
therefore indicate their potential in engineering applications
Hybridizing WENO implementations of interpolation and reconstruction-wise operation for upwind-biased schemes with free-stream preservation
Cases have shown that WENO schemes usually behave robustly on problems
containing shocks with high pressure ratios when uniformed or smooth grids are
present, while nonlinear schemes based on WENO interpolations might relatively
be liable to numerical instability. In the meanwhile, the latter have
manifested their advantages in computations on grids of bad quality, because
the free-stream preservation is easily realized there, and what is more
flux-splitting schemes with low dissipations can be engaged inherently as well.
Targeting at above dissatisfactions, a method by hybridizing WENO
implementations of interpolation and reconstruction-wise operation for
upwind-biased schemes with flux splitting employed is proposed and
corresponding third-, fifth- and seventh-order upwind-biased schemes are
proposed. Based on the understandings of [Q. Li, et al. Commun. Comput. Phys.
22 (2017) 64-94], the free-stream preservation of proposed schemes is achieved
with incorporation of frozen grid metrics in WENO reconstructions-wise
operations on split fluxes. In proposed schemes, flux-splitting schemes with
low dissipation can also be applied for the flux on a cell edge. As a
byproduct, an implementation of WENO scheme with free-stream preservation is
obtained. Numerical examples are provided as following with the third- and
fifth-order schemes being tested. In tests of free-stream preservation, the
property is achieved as expected (including two implementations of WENO). The
computation of 1-D Sod problem shows the capability of proposed schemes on
solving ordinary shock discontinuity. 2-D vortex preservation and double Mach
reflection are tested on uniformed and randomized grids. The accomplishment by
proposed schemes manifests their capability and robustness on solving problems
under rigorous circumstances
Representations by
Let be the representation number of a nonnegative integer by the
quaternary quadratic form . We
first prove the identity for any prime
different from 13 and any positive integer prime to , which was
conjectured in [Eum et al, A modularity criterion for Klein forms, with an
application to modular forms of level 13, J. Math. Anal. Appl. 375 (2011),
28--41]. And, we explicitly determine a concise formula for the number
as well for any integer
Phase Balancing Using Energy Storage in Power Grids under Uncertainty
Phase balancing is essential to safe power system operation. We consider a
substation connected to multiple phases, each with single-phase loads,
generation, and energy storage. A representative of the substation operates the
system and aims to minimize the cost of all phases and to balance loads among
phases. We first consider ideal energy storage with lossless charging and
discharging, and propose both centralized and distributed real-time algorithms
taking into account system uncertainty. The proposed algorithm does not require
any system statistics and asymptotically achieves the minimum system cost with
large energy storage. We then extend the algorithm to accommodate more
realistic non-ideal energy storage that has imperfect charging and discharging.
The performance of the proposed algorithm is evaluated through extensive
simulation and compared with that of a benchmark greedy algorithm. Simulation
shows that our algorithm leads to strong performance over a wide range of
storage characteristics
The Spin-weighted Spheroidal Wave functions in the Case of s=1/2
The spin-weighted spheroidal equations in the case s=1/2 is thoroughly
studied in the paper by means of the perturbation method in supersymmetry
quantum mechanics. The first-five terms of the super-potential in the series of
the parameter beta are given. The general form of the nth term of the
superpotential is also obtained, which could derived from the previous terms
W_{k}, k<n. From the results, it is easy to give the ground eigenfunction of
the equation. Furthermore, the shape-invariance property is investigated in the
series form of the parameter beta and is proven kept in this series form for
the equations. This nice property guarantee one could obtain the excited
eigenfunctions in the series form from the ground eigenfunctions by the method
in supersymmetry quantum mechanics. This shows the perturbation method method
in supersymmetry quantum mechanics could solve the spin-weight spheroidal wave
equations completely in the series form of the small parameter beta
Exploration quantum steering, nonlocality and entanglement of two-qubit X-state in structured reservoirs
In this work, there are two parties, Alice on Earth and Bob on the satellite,
which initially share an entangled state, and some open problems, which emerge
during quantum steering that Alice remotely steers Bob, are investigated. Our
analytical results indicate that all entangled pure states and maximally
entangled evolution states (EESs) are steerable, and not every entangled
evolution state is steerable and some steerable states are only locally
correlated. Besides, quantum steering from Alice to Bob experiences a "sudden
death" with increasing decoherence strength. However, shortly after that,
quantum steering experiences a recovery with the increase of decoherence
strength in bit flip (BF) and phase flip (PF) channels. Interestingly, while
they initially share an entangled pure state, all EESs are steerable and obey
Bell nonlocality in PF and phase damping channels. In BF channels, all
steerable states can violate Bell-CHSH inequality, but some EESs are unable to
be employed to realize steering. However, when they initially share an
entangled mixed state, the outcome is different from that of the pure state.
Furthermore, the steerability of entangled mixed states is weaker than that of
entangled pure states. Thereby, decoherence can induce the degradation of
quantum steering, and the steerability of state is associated with the
interaction between quantum systems and reservoirs.Comment: 17 pages, 4 figures and 3 table
- β¦