Intermetallic phase formation in directionally solidified Al−Si−Fe alloy

The present study has been undertaken to better understand the solidification behavior of Al−Si−Fe alloys containing 7wt.% Si and 0.9wt.% Fe, with particular regard to the formation of phase during controlled solidification and influence of growth rates on intermetallic phase selection. The alloys studied were Al-7Si-0.9Fe alloys, which were produced by a modified Bridgman solidification arrangement. These alloys were solidified unidirectionally with different growth rates (1–30mm/min). The solidified microstructure of these alloys consists of the growth of primary aluminum and multiple second phase reactions.     

A method for diagnosis of current faults in antenna arrays using neural networks

A method for detection of faulty elements in antenna arrays from far‐field radiation pattern is presented. The proposed technique finds variation of current from correct values in the faulty elements. A step wise approach is proposed to determine magnitude and phase of current excitation and location of faulty element using neural networks. The results with radial basis function neural network and probabilistic neural network are compared. © 2008 Wiley Periodicals, Inc. Int J RF and Microwave CAE, 2009.     

考虑电网阻抗耦合的模块化多电平换流器交直流侧阻抗通用计算方法

以模块化多电平换流器(modular multilevel converter,MMC)为技术路线的柔性直流输电技术在风电接入、电网异步互联等领域迅速发展。MMC的阻抗建模是分析柔性直流输电系统振荡起源的重要依据。文中分析MMC在交、直流侧激励下的谐波传递机制,建立一种适用于交、直流侧阻抗计算的通用方法。对一次系统频域建模关联了MMC所连接的交、直流侧网络阻抗,并考虑包含解耦双同步参考坐标系锁相环及负序内环控制在内的全部控制模块。通过求解线性方程组对MMC阻抗进行计算,并在PSCAD/EMTDC环境中对双端背靠背MMC系统在多种工况下1～5kHz频段内进行扫频,验证该方法的准确性,并详细分析网络阻抗耦合、控制链路延时、功率等级、负序内环和外环控制等因素对MMC阻抗的影响。     

Tuning of multi-loop PI controllers based on gain and phase margin specifications

In this paper, a single-iteration strategy is proposed for the design of a multi-loop PI controller to achieve the desired gain and phase margins for two-input and two-output (TITO) processes. To handle loop interactions, a TITO system is converted into two equivalent single loops with uncertainties drawn from interactions. The maximum uncertainty is estimated for the initial controller design in one loop and single-input and single-output (SISO) controller design is applied. This controller is substituted to other equivalent loop for design, and finally, the first loop controller is refined on knowledge of other loop controller. For SISO controller tuning, a new method is presented to determine the achievable gain and phase margins as well as the relevant controller parameters. Examples are given for illustration and comparison.     

Virtual Reference Feedback Tuning for non-minimum phase plants

Model reference control design methods fail when the plant has one or more non-minimum phase zeros that are not included in the reference model, leading possibly to an unstable closed loop. This is a very serious problem for data-based control design methods, where the plant is typically unknown. In this paper, we extend the Virtual Reference Feedback Tuning method to non-minimum phase plants. This extension is based on the idea proposed in Lecchini and Gevers (2002) for Iterative Feedback Tuning. We present a simple two-step procedure that can cope with the situation where the unknown plant may or may not have non-minimum phase zeros.     

湿法相分离不对称超滤膜形成机理

本文选择了憎水的极怀非普质子性聚砜和亲水的极性质子怀聚砜酰胺两种膜材料，从铸膜液组成和凝胶过程两方面，用气相色谱和高效液相色谱研究了表征膜材料－溶剂－添加剂－水作用力的混合自由焓，平衡分配常数，及其与膜性能，不同溶剂特性粘度，雾点值和溶解度参数的关系，提出了铸膜液中有机溶剂的作用机理，及不对称超滤膜形成的一些规律。     

建设项目设计阶段投资控制系统的建立与分析

针对建设设计阶段独立使用价值工程、优化设计和限额设计等方法进行投资控制的局限性,借鉴系统论、控制论、信息论等思想和方法,建立了设计阶段投资控制系统。系统主要由探测元件、控制元件和执行元件组成,探测元件进行设计阶段的信息收集;控制元件通过审核将各项投资控制活动与投资控制目标进行对比,提出应对策略;执行元件完成应对策略。通过投资控制系统的执行,实现对设计阶段各项活动的全面系统控制,从管理层面上解决设计阶段投资控制活动割裂问题,进而改善设计阶段整体投资控制效果。     

弱耦合状态下的量子逻辑门和远距离量子态的转移（英文）

依据弱耦合状态下的量子点-腔系统,提出了1个控制Z门和1个条件相位门.利用这个控制Z门并且测量光子和第1个电子的状态,可以将这个量子态转移到第2个电子上,从而实现2个远距离量子点之间的远程量子态转移.这些方案都是在弱耦合状态下实现的,不需要对腔有严格的要求.