Weak Finite—Size Dependence of Velocity and Strong Phase Dependence of Central Charge

We study the finite-size scaling behavior of velocity and central charge for different coupling constants and different phases in -dimensional lattice model in very short chains. Using XXZ spin 1/2 chains with 15 or fewer sites, we demonstrate the weak finite-size dependence of spinon velocity for any magnitude of coupling strength and the strong phase dependence of central charge. This behavior of velocity and central charge in different coupling constants and different phases gives a method to determine phase transitions of -dimensional models. This method is simple and efficient by utilizing only the ground state energy of very short finite-size chains. It is also general and powerful for various one-dimensional lattice models and it uncovers even the weakest Berezinski?Kosterlitz?Thouless phase transitions.

Centralized Bi-level Spatial-Temporal Coordination Charging Strategy for Area Electric Vehicles

Increased penetration of electric vehicles(EVs)is expected to impact power system performance in adverse ways,e.g.,overloading,uncertain power quality,and increased voltage fluctuation,particularly at the distribution level.Most EV charging control strategies that have been proposed only benefit the grid or EV users.A centralized EV charging strategy based on bilevel optimization is proposed in this paper with the objectives of deriving benefits for the grid and EV users simultaneously.The proposed strategy involves distributing the EV charging load more beneficially across both spatial and temporal levels.In the spatial problem,the whole fleet of EVs is controlled to minimize load variance as spatial coordination,with total charging rate and energy needed as the constraint.While in the temporal problem,EVs in each aggregator are controlled to minimize the charging cost or maximize the EV user’s degree of satisfaction with each aggregator’s charging rate and energy needed as the constraint.The proposed bi-level charging strategy is transformed to a single-stage optimization problem and solved using the classical optimization method.The impacts of uncontrolled charging on the grid and EV users are studied using the Monte Carlo Simulation(MCS)method.Then,the effectiveness of the proposed charging strategy is demonstrated via results obtained in the MCS.

Influence of Burden Distribution on Temperature Distribution in COREX Melter Gasifier

The temperature distribution of COREX melter gasifier was studied by using a two-dimensional 1/30 scale thermal dynamic model.A set of operating conditions,such as radial distribution of direct reduction iron（DRI） to lump coal and coke volume ratio,coke charging location,coke charging amount and coke size,were taken into account.The results show that the temperature near the wall region decreases with the decrease of the radial distribution of DRI to lump coal and coke volume ratio.The temperature with central coke charging is higher than that without central coke column.Furthermore,the temperature significantly increases with the increase of central coke charging amount.With the increase of intermediate coke charging amount,the temperature near the wall region decreases while the temperature in the intermediate region increases.The temperature increases with the increase of coke size whether charging central coke or intermediate coke.