潜艇推进器模型参考模糊自适应PID控制方法研究

本文主要介绍了模型参考模糊自适应PID控制在潜艇推进液压伺服系统中的应用。潜艇推进液压伺服系统因随外界环境的变化而变化,因此常规PID控制无法满足要求,本文采用模型参考模糊自适应PID控制对其进行控制,并对控制结果进行仿真分析,通过与传统PID控制进行比较从而得出该控制方法可以有效抑制负载干扰和参数扰动,具有很强的鲁棒性。     

Novel Lyapunov-based rapid and ripple-free MPPT using a robust model reference adaptive controller for solar PV system

The technological, economic, and environmental benefits of photovoltaic (PV) systems have led to their widespread adoption in recent years as a source of electricity generation. However, precisely identifying a PV system''s maximum power point (MPP) under normal and shaded weather conditions is crucial to conserving the maximum generated power. One of the biggest concerns with a PV system is the existence of partial shading, which produces multiple peaks in the P–V characteristic curve. In these circumstances, classical maximum power point tracking (MPPT) approaches are prone to getting stuck on local peaks and failing to follow the global maximum power point (GMPP). To overcome such obstacles, a new Lyapunov-based Robust Model Reference Adaptive Controller (LRMRAC) is designed and implemented to reach GMPP rapidly and ripple-free. The proposed controller also achieves MPP accurately under slow, abrupt and rapid changes in radiation, temperature and load profile. Simulation and OPAL-RT real-time simulators in various scenarios are performed to verify the superiority of the proposed approach over the other state-of-the-art methods, i.e., ANFIS, INC, VSPO, and P&O. MPP and GMPP are accomplished in less than 3.8 ms and 10 ms, respectively. Based on the results presented, the LRMRAC controller appears to be a promising technique for MPPT in a PV system.     

抑制间接矩阵变换器共模电压的调制策略

间接矩阵变换器在运行过程中会产生较大的共模电压,对电机系统造成严重的电磁干扰,影响系统正常运行。针对这一问题,提出一种新的空间矢量调制策略降低共模电压大小,改善输出电压性能。首先,将整流级空间矢量重新划分区域,根据参考电流矢量所在区域选择3个相邻的有效电流矢量,将有效矢量下的平均直流母线电压维持在一个恒定值,保证整流级的最大输出电压。其次,逆变级采用无零矢量调制策略,通过使用3个有效电压矢量合成所需要的输出电压,将共模电压峰值抑制到输入相电压幅值的57.7%。与传统调制策略相比,提出的调制策略不仅可以减轻系统计算负担,还可以减少系统输入输出谐波,改善输入输出波形质量。最后,通过Matlab/Simulink和实验平台搭建相应模型,仿真和实验结果验证了所提出策略的有效性。     

基于多元回归算法的PaaS平台资源自动化分配方法

针对PaaS平台下资源离散性过强、数据量过大导致的分配不均问题,提出了一种基于多元回归的自动化分配算法实现有效解决。统计所有资源数据样本,利用多元回归算法计算观测序列中残差平方和最小的样本集,代入损失函数中求出损失差值,得到最小损失值,根据梯度下降规律寻找集合中梯度值最优样本,以该样本作为分配参照。设立一套内容为分配与参考样本值相关度最高的资源数据约束条件,不断迭代计算直至求得所有符合约束条件的资源,将符合条件的为一组分配,剩余为另一组分配。根据资源的时间和位数的分布序列,不断实施离散捕捉查找残留资源,再实施二次分配。仿真实验证明,所提方法分配后PaaS平台资源吞吐量增加,消耗代价减少,算法分配时间较低,整体实用能力强。     

基于IGD+指标的两阶段选择高维多目标进化算法

针对在高维空间下多目标进化算法难以维持种群收敛性和多样性平衡的问题, 本文提出一个基于IGD+指标的两阶段选择高维多目标进化算法(MaOEA–ITS). 在第1阶段, 算法基于IGD+指标选择收敛性良好的精英个体, 其所需的参考点通过引入切割平面截距法构建. 在第2阶段, MaOEA–ITS使用模糊c均值算法对参考向量进行聚类, 聚类后的参考向量引导种群分解策略对剩余个体进行环境选择, 从而维持种群的多样性. 另外, 为了保护能够提高种群多样性的极值解, 本文提出一个参考点分布自适应策略. 最后, 通过仿真实验来验证MaOEA–ITS的有效性和优越性.     

RTDMiner: 基于数据挖掘的引用计数更新缺陷检测方法

在Linux内核等大型底层系统中广泛采用引用计数来管理共享资源.引用计数需要与引用资源的对象个数保持一致,否则可能导致不恰当引用计数更新缺陷,使得资源永远无法释放或者被提前释放.为检测不恰当引用计数更新缺陷,现有静态检测方法通常需要知道哪些函数增加引用计数,哪些函数减少引用计数.而手动获取这些关于引用计数的先验知识过于费时且可能有遗漏.基于挖掘的缺陷检测方法虽然可以减少对先验知识的依赖,但难以有效检测像不恰当引用计数更新缺陷这类路径敏感的缺陷.为此,提出一个将数据挖掘技术和静态分析技术深度融合的不恰当引用计数更新缺陷检测方法 RTDMiner.首先,根据引用计数的通用规律,利用数据挖掘技术从大规模代码中自动识别增加或减少引用计数的函数.然后,采用路径敏感的静态分析方法检测增加了引用计数但没有减少引用计数的缺陷路径.为了降低误报,在检测阶段再次利用数据挖掘技术来识别例外模式.在Linux内核上的实验结果表明,所提方法能够以将近90%的准确率自动识别增加或减少引用计数的函数.而且RTDMiner检测到的排行靠前的50个疑似缺陷中已经有24个被内核维护人员确认为真实缺陷.     

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。     

Data-driven dual-rate cascade control and application to pitch angle control of UAV

A data-driven design method for a cascade control system is proposed. The cascade control system consists of inner and outer loops, where the control interval of the outer loop is an integer multiple of the inner loop; hence, the system is a dual-rate system. In the proposed method, controllers in the inner and outer loops are designed based on one-shot data. In such a dual-rate cascade system, since the controllers are designed using different data-rate signals, the lifting technique is applied to align the dual-rate data. To show its effectiveness, the proposed method is compared with a conventional single-rate cascade control method, and numerical simulations and experiments are presented to examine servo and regulation performance.     

Joint pricing and advertising strategy with reference price effect

Consumers are susceptible to reference price effects when they make purchase decisions for a certain product. Meanwhile, the sales price and advertisement are the determinable factors that have impact on consumers’ reference price which are also fundamental marketing strategies. Therefore, how to determine an appropriate sales price and advertising effort level to maximise firms’ profits is an essential task. A joint pricing and advertising problem for a monopolistic firm with consideration of reference price effect is investigated, where consumer demand rate is price-sensitivity and depends on the gap between the sales price and the reference price in consumers’ mind. An optimisation model is established to maximise the firm’s total profit by making a joint pricing and advertising strategy. The static and dynamic joint strategies are obtained by applying Pontryagin’s maximum principle. Results show that the dynamic strategies dominate the static ones. Furthermore, the dynamic pricing and dynamic advertising strategies are strategic complements. Additionally, the length of the sales period plays a key role in determining the superiority of the two dynamic strategies. Specifically, a relatively short sales period highlights the value of the dynamic advertising while a long sales period strengthens the function of the dynamic pricing.     

Myopic vs. far-sighted behaviours in a revenue-sharing supply chain with reference quality effects

In this paper, we consider a dynamic supply chain where a manufacturer produces and distributes a featured product through an exclusive retailer to end consumers. The manufacturer decides the product quality and wholesale price, while the retailer sets the retail price in the presence of a revenue-sharing contract and consumers’ reference quality effects. The objective of this study is to investigate the impacts of myopic behaviour regarding the reference quality on the product quality and pricing strategies and profits of both members. Our results suggest that the manufacturer’s myopia leads to a higher quality, higher price strategy and a higher quality–price ratio which benefits consumers. Meanwhile, relative to the far-sighted behaviour, myopia results in a more quality-sensitive but less price-sensitive market demand. What’s more, we find that the manufacturer is apt to act in a far-sighted way, but the retailer isn’t always willing to cooperate with a far-sighted manufacturer. Taking myopic strategies for both members is likely to gain a high profit of the whole supply chain for a relatively high marginal contribution of product quality on demand and a relatively low revenue-sharing proportion.