17,382 research outputs found
Quantum Phase diagram and time-of-flight absorption pictures of ultracold Bose system in a square optical superlattice
In this letter, by the use of the generalized effective potential theory,
with the help of process-chain approach under the framework of Kato formulation
of perturbation expansion, we calculate out the quantum phase diagram up to
8-th order for an ultracold Bose system in a square optical superlattice. Base
on these perturbative data, with the help of the linear fit extrapolation
technique, more accurate results are gotten, which are in excellent agreement
with recent Monte-Carlo numerical results. Moreover, by employing the
generalized re-summed Green's function method and cumulant expansion, the
momentum distribution function of the system is also calculated analytically
and the time-of-flight absorption pictures of the system are plotted.Comment: 6 pages, 6 figure
Competitive Charging Station Pricing for Plug-in Electric Vehicles
This paper considers the problem of charging station pricing and plug-in
electric vehicles (PEVs) station selection. When a PEV needs to be charged, it
selects a charging station by considering the charging prices, waiting times,
and travel distances. Each charging station optimizes its charging price based
on the prediction of the PEVs' charging station selection decisions and the
other station's pricing decision, in order to maximize its profit. To obtain
insights of such a highly coupled system, we consider a one-dimensional system
with two competing charging stations and Poisson arriving PEVs. We propose a
multi-leader-multi-follower Stackelberg game model, in which the charging
stations (leaders) announce their charging prices in Stage I, and the PEVs
(followers) make their charging station selections in Stage II. We show that
there always exists a unique charging station selection equilibrium in Stage
II, and such equilibrium depends on the charging stations' service capacities
and the price difference between them. We then characterize the sufficient
conditions for the existence and uniqueness of the pricing equilibrium in Stage
I. We also develop a low complexity algorithm that efficiently computes the
pricing equilibrium and the subgame perfect equilibrium of the two-stage
Stackelberg game.Comment: 15 pages, 21 figure
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