自适应反推神经网络的转台鲁棒控制器设计

针对未知非线性、外界干扰和参数摄动等不确定因素对实际转台控制系统的影响,提出了自适应反推神经网络的转台鲁棒控制器设计.首先给出自适应Backstepping控制器的设计方法及步骤,接着采用RBF神经网络对转台对象参数的不确定因素上界值加以辨识,实现转台系统的鲁棒控制.其中Backstepping鲁棒控制作为主控制器,RBF神经网络实现了不确定上界值的在线辨识.仿真结果表明,自适应Backstepping神经网络控制很好地克服了对象的不确定性,实现控制系统的较强鲁棒性,适于高精度飞行仿真转台系统的实时鲁棒控制.     

Effect of dietary zinc levels on health and productivity of gilts and sows through two parities

The influence of 0, 50, 500 or 5,000 ppm supplemental Zn on productive characteristics, weight change, and serum and organ mineral concentrations of 60 crossbred and purebred Yorkshire gilts was evaluated. Gilts were fed their respective treatment from 30 kg body weight until the completion of two parities. Sows fed 5,000 ppm supplemental Zn weighed significantly less than sows from the other treatments when killed. Serum alkaline phosphatase activity was higher for the sows fed the highest level of Zn in all replications at 10 and 14 mo of age than for sows from the other treatments. Sows fed 0, 50 or 500 ppm had lower serum Zn and higher serum Cu concentrations than sows fed 5,000 ppm Zn at 10 and 14 mo of age. The number of pigs farrowed (total and live) and birth weight were not affected by dam's dietary treatment. However, sows receiving no additional Zn had a higher number of abnormal pigs/litter than sows on the other treatments. Sows fed 5,000 ppm additional Zn weaned fewer pigs that weighed less at weaning than sows on the other treatments. The concentration of Zn in the sow's liver increased significantly and liver Cu decreased as dietary level of Zn increased. Sows receiving 5,000 ppm Zn had lower hepatic Fe stores compared with sows receiving 500 ppm Zn. Elevated renal Cu and Zn concentrations were found in sows fed the highest level of Zn supplementation. The Zn concentration was higher and the Cu concentration lower in the aorta of sows fed 5,000 ppm Zn compared with sows fed 0 or 50 ppm additional Zn. Incidence of osteochondrosis was higher in sows supplemented with 5,000 ppm Zn than for sows from the other treatments.     

参数不确定机械伺服系统的鲁棒非线性摩擦补偿控制

对含非线性摩擦环节的机械伺服系统,提出一种基于Lyapunov方法的鲁棒非线性控制方法,通过引入非线性增益和摩擦补偿项,来克服参数不确定性和补偿非线性摩擦,从而保证跟踪误差渐进收敛.对转台系统的实验研究,表明了该方法的有效性.     

DFNN及其在非线性动态系统中的应用

为了更好地辨识和控制非线性动态系统,在FNN基础上对其进行优化和改进,形成了动态模糊神经网络(DFNN)。给出了基于BP梯度算法的参数迭代学习算法,并应用于某非线性动态系统仿真试验中。仿真试验表明,该网络比单纯的FNN具有更强的辨识和控制能力,应用于非线性动态系统的控制中可以有效解决系统的非线性和不确定性,提高系统的跟踪性能,并且控制系统具有很强的鲁棒性。     

云中基于蚁群算法改进的负载均衡策略

针对云计算虚拟化资源中,提高资源利用率、负载均衡度的问题,在蚁群算法的基础上,提出云中节点间负载均衡的改进算法。前向蚂蚁检测节点的类型、记录节点信息,遇到负载节点时留下觅食信息素;后向蚂蚁依据循迹信息素追溯回负载节点,合理分配超载节点任务。所有蚂蚁不再更新自己的结果集,而是致力于更新单个结果集,在搜索过程中依据节点类型动态地修改路径信息素。在Cloudsim平台下进行的仿真实验验证了改进算法的有效性。     

雷达寻的制导半实物仿真误差研究

在介绍雷达寻的制导控制基本原理、半实物基本方法及仿真原理的基础上,详细介绍了雷达寻的制导控制半实物仿真系统的组成、各关键设备的工作原理并进行了主要误差因素分析,同时对关键仿真设备的误差进行研究,并建立数学模型,进一步推导出此类雷达仿真系统具有一般意义的仿真误差模型.最后通过型号半实物仿真试验对仿真系统的仿真精度进行验证.仿真试验表明,该半实物仿真系统的仿真精度满足控制系统半实物仿真试验的要求.     

Improved localization in a generalized Hough scheme for the detection of straight edges

Hough transforms are widely used for the location of straight edges in digital images, yet most common line parametrization schemes give no information on longitudinal localization. The generalized Hough transform goes some way to overcoming this problem. This paper studies how to improve the situation further. A trade-off between sensitivity and localization is found; in practical situations this results in significantly greater accuracy, but the important gain is a reduction in the number of ambiguities introduced by interactions between the transforms of unrelated straight edges.     

直接转矩控制研究现状与前景

介绍了直接转矩控制的研究现状，就几个关键问题进行了讲座，并分析了其今后的发展方向。     

Management of upper urinary tract calculi with ureteroscopic techniques

Frequent loss of heterozygosity on chromosome 8p in a variety of human malignancies, including head and neck cancers, has suggested the presence of a tumor suppressor gene (or genes) associated with the pathogenesis of these cancers. To test the role of genetic alterations at 8p23 in oral carcinogenesis, we studied 51 squamous cell carcinomas of the head and neck and 29 oral squamous cell carcinoma cell lines for allelic loss using 7 microsatellite markers spanning approximately 5 cM of chromosome band 8p23. Twenty-three of 51 tumors (45%) and 23 of 29 cell lines (79%) showed allelic loss at 1 or more loci. Three cell lines showed homozygous deletion of loci within a 3 cM region defined by the markers D8S1781 and D8S262. Our results suggest that a tumor suppressor gene (or genes) is located in 8p23 and is associated with the development and/or progression of oral carcinomas.