In the presence of multiple non-regenerative relays, we derived optimal joint power allocation, relay selection, and subchannel pairing schemes in orthogonal frequency division multiplexing(OFDM) based wireless networ...In the presence of multiple non-regenerative relays, we derived optimal joint power allocation, relay selection, and subchannel pairing schemes in orthogonal frequency division multiplexing(OFDM) based wireless networks.The Lagrange dual method was employed to design the optimal algorithm.First, the optimization problem was formulated for the single-relay system and the optimal centralized algorithm was presented by resolving the dual problem.Next, the optimal algorithm for a multi-relay system was proposed in a similar way.Compared with the exhaustive search method, the computational complexity of the proposed optimal algorithms was reduced from non-polynomial to polynomial time.Finally, the centralized algorithm was extended to the distributed algorithm, which was more feasible for the practical system.Simulation results verify our analysis.展开更多
The service quality of a workstation depends mainly on its service load, ifnot taking into account all kinds of devices' break-downs. In this article, an optimization modelwith inequality constraints is proposed, ...The service quality of a workstation depends mainly on its service load, ifnot taking into account all kinds of devices' break-downs. In this article, an optimization modelwith inequality constraints is proposed, which aims to minimize the service load. A noveltransformation of optimization variables is also devised and the constraints are properly combinedso as to make this model into a convex one, whose corresponding Lagrange function and the KKTconditions are established afterwards. The interior-point method for convex optimization ispresented here as an efficient computation tool. Finally, this model is evaluated by a real example,from which conclusions are reached that the interior-point method possesses advantages such asfaster convergeoce and fewer iterations and it is possible to make complicated nonlinearoptimization problems exhibit convexity so as to obtain the optimum.展开更多
文摘可交易能源系统基于市场运行机制可以充分发挥产消者的资源灵活性,并保障电力系统的安全,经济运行。针对含光伏(photovoltaic,PV)出力、储能装置(energy storage system,ESS)、电动汽车(electric vehicle,EV)以及空调(heating ventilating and air conditioning,HVAC)资源的多个产消者组成的智能园区为研究对象,首先对产消者资源灵活性进行整合与量化并根据交易流向进行解耦。其次,为确保园区交互平台中参与用户的信息安全,实现园区内电能共享、就地消纳,提出了基于次梯度法的成本最小化算法及其分布式凸优化运行框架。优化子问题可以通过有限的信息交互迭代收敛于全局最优解,实现产消者之间的P2P(peer-to-peer)电能交易,最后通过算例验证了所提模型的有效性。
基金Project supported by the National Natural Science Foundation of China (No. 60802012)the National Basic Research Program (973) of China (No. 2009CB320405)+1 种基金the Educational Commission of Zhejiang Province, China (No. 20070234)Huawei Collaborative Research Funding (No. YBWL2008046)
文摘In the presence of multiple non-regenerative relays, we derived optimal joint power allocation, relay selection, and subchannel pairing schemes in orthogonal frequency division multiplexing(OFDM) based wireless networks.The Lagrange dual method was employed to design the optimal algorithm.First, the optimization problem was formulated for the single-relay system and the optimal centralized algorithm was presented by resolving the dual problem.Next, the optimal algorithm for a multi-relay system was proposed in a similar way.Compared with the exhaustive search method, the computational complexity of the proposed optimal algorithms was reduced from non-polynomial to polynomial time.Finally, the centralized algorithm was extended to the distributed algorithm, which was more feasible for the practical system.Simulation results verify our analysis.
文摘The service quality of a workstation depends mainly on its service load, ifnot taking into account all kinds of devices' break-downs. In this article, an optimization modelwith inequality constraints is proposed, which aims to minimize the service load. A noveltransformation of optimization variables is also devised and the constraints are properly combinedso as to make this model into a convex one, whose corresponding Lagrange function and the KKTconditions are established afterwards. The interior-point method for convex optimization ispresented here as an efficient computation tool. Finally, this model is evaluated by a real example,from which conclusions are reached that the interior-point method possesses advantages such asfaster convergeoce and fewer iterations and it is possible to make complicated nonlinearoptimization problems exhibit convexity so as to obtain the optimum.
