两台可拒绝同类机在线排序问题近似算法的参数性能比

讨论两台可拒绝同类机在线排序问题的近似算法 .设两台机器的速度之比为 s(≥ 1) .工件逐个到位 ,可以被加工 ,也可以被拒绝 ,但要付出相应的罚值pj.并且只有在安排完当前工件之后 ,下一个工件才到达 .目标函数要求被加工工件集的最迟工件完工时间与被拒绝工件集的总罚值之和达到最小 .文中设计出线性时间的 RL S(α)算法 ,并证明了其关于 s的参数紧界 ,这个界于 s=1以及 s≥(5 +1) / 2均是不可改进的 .

一特殊情形的二、三台同类机上排序问题的最好在线算法

该文首先给出两台同类机在线排序问题 Q2 ∥ Cmax之 L S算法的参数性能比 ,并证明 LS算法对于其已是最好的在线算法。然后进一步给出 LS算法对于特殊情形 s1=s≥ 1,s2 =s3 =1的 Q3 ∥ Cmax问题的参数紧界 ,并证明当 s≥ 2时 ,LS算法亦是最好的在线算法。

Research on Power Control of Wind Power Generation Based on Neural Network Adaptive Control

For the characteristics of wind power generation system is multivariable, nonlinear and random, in this paper the neural network PID adaptive control is adopted. The size of pitch angle is adjusted in time to improve the perfomance of power control. The PID parameters are corrected by the gradient descent method, and Radial Basis Functiion （RBF） neural network is used as the system identifier in this method. Sinlation results show that by using neural network adaptive PID controller the generator power control can inhibit effectively the speed and affect the output prover of generator. The dynamic performnce and robustness of the controlled system is good, and the peformance of wind power system is improved.

Parametric optimization and performance comparison of organic Rankine cycle with simulated annealing algorithm

Taking the ratio of heat transfer area to net power and heat recovery efficiency into account, a multi-objective mathematical model was developed for organic Rankine cycle （ORC）. Working fluids considered were R123, R134a, R141b, R227ea and R245fa. Under the given conditions, the parameters including evaporating and condensing pressures, working fluid and cooling water velocities were optimized by simulated annealing algorithm. The results show that the optimal evaporating pressure increases with the heat source temperature increasing. Compared with other working fluids, R123 is the best choice for the temperature range of 100--180℃ and R141 b shows better performance when the temperature is higher than 180 ℃. Economic characteristic of system decreases rapidly with the decrease of heat source temperature. ORC system is uneconomical for the heat source temperature lower than 100℃.

In-Plane and Out-of-Plane Mechanical Properties of Zero Poisson’s Ratio Cellular Structures for Morphing Application

Intelligent structures like zero Poisson’s ratio(ZPR)cellular structures have been widely applied to the engineering fields such as morphing wings in recent decades,owing to their outstanding characteristics including light weight and low effective modulus. In-plane and out-of-plane mechanical properties of ZPR cellular structures are investigated in this paper. A theoretical method for calculating in-plane tensile modulus,in-plane shear modulus and out-of-plane bending modulus of ZPR cellular structures is proposed,and the impacts of the unit cell geometrical configurations on in-plane tensile modulus,in-plane shear modulus and out-of-plane bending modulus are studied systematically based on finite element(FE)simulation. Experimental tests validate the feasibility and effectiveness of the theoretical and FE analysis. And the results show that the in-plane and out-of-plane mechanical properties of ZPR cellular structures can be manipulated by designing cell geometrical parameters.

CONSTRUCTIONS OF UNITARY SPACE-TIME CODES WITH FULL DIVERSITY

The problem of constructing unitary space-time codes with high diversity product has been studied in many prior works.Recently,constructions of parametric fully diverse unitary space-time codes for prime number antennas system have been introduced.In this paper,the authors propose new construction methods based on these constructions.And fully diverse codes of any number antennas are obtained from these constructions.Unitary space-time codes from present constructions are found to have better error performance than many best known ones.