EWMA控制图在MSA稳定性分析中的应用

针对传统的 Shewhart 控制图使用当前观测数据进行测量系统分析(MSA)的稳定性分析,不易检测出过程均值中存在的小偏移,而指数加权滑动平均(EWMA)和累计和(CUSUM)控制图考虑了历史数据,可以克服Shewhart 控制图在小波动情况下检测能力不足的缺陷:首先通过 Montle-Carlo 模拟计算控制图性能评价指标ARL(average run length),分析了 EWMA 和 CUSUM 控制图的优越性;然后给出了 EWMA 控制图在 MSA 稳定性分析中的实施步骤.示例分析表明 EWMA 在小波动时比 CUSUM 和 Shewhart 控制图更为有效.     

一类分布参数混合系统的稳定性分析

将混合系统推广到分布参数环境下,提出分布参数混合系统的概念.基于混合系统和分布参数系统的建模方法,建立了一类分布参数混合系统的模型,并对其稳定性进行分析.运用算子半群理论以及混合系统的五元组描述法及其稳定性关系比较理论的结论,通过选择适当的映射,将分布参数混合系统的的稳定性问题转化为集中参数下混合系统稳定性问题,进而得出了一致渐近稳定的充分条件并加以证明.仿真实例验证了文中结论的正确性.     

两类不确定奇异时滞系统鲁棒稳定的相关型判据

研究了不确定奇异时滞系统的鲁棒稳定性问题。首先以线性矩阵不等式的形式给出了奇异时滞系统正则,无脉冲模且零解渐近稳定的一种新的时滞相关型判据。通过引入新的参数避免了利用不等式处理交叉项,从而使该判据具有较小的保守性。最后,利用研究结果,给出了两类不确定奇异时滞系统新的时滞相关型鲁棒稳定性判据。     

CMAC神经网络用于分析和设计非线性过程控制系统(Ⅱ)——控制策略

本文是基于 CMAC神经网络分析和设计复杂控制系统的第二部分 ,提出了基于评价函数和CMAC预测器的控制器的设计方法 ,通过分析控制算法的收敛性和控制系统的稳定性 ,得出了控制器参数的选取方法 .该方案适用于过程的输入输出数据是可测的 ,并且可用第一部分提出的方法得到对象的 CMA C预测器 .仿真实例证明该方案是正确和实用的.     

Modulation of protein biophysical properties by chemical glycosylation: biochemical insights and biomedical implications

Glycosylation constitutes one of the most important posttranslational modifications employed by biological systems to modulate protein biophysical properties. Due to the direct biochemical and biomedical implications of achieving control over protein stability and function by chemical means, there has been great interest in recent years towards the development of chemical strategies for protein glycosylation. Since current knowledge about glycoprotein biophysics has been mainly derived from the study of naturally glycosylated proteins, chemical glycosylation provides novel insights into its mechanistic understanding by affording control over glycosylation parameters. This review presents a survey of the effects that natural and chemical glycosylation have on the fundamental biophysical properties of proteins (structure, dynamics, stability, and function). This is complemented by a mechanistic discussion of how glycans achieve such effects and discussion of the implications of employing chemical glycosylation as a tool to exert control over protein biophysical properties within biochemical and biomedical applications. Received 15 December 2006; received after revision 28 March 2007; accepted 25 April 2007     

The molecular role of the Rothmund-Thomson-, RAPADILINO- and Baller-Gerold-gene product, RECQL4: recent progress

The RecQ family of DNA helicases is highly conserved throughout evolution and plays an important role in the maintenance of genomic stability in all organisms. Mutations in three of the five known family members in humans, BLM, WRN and RECQL4, give rise to disorders that are characterized by predisposition to cancer and premature aging, emphasizing the importance of studying the RecQ proteins and their cellular activities. Interestingly, three autosomal recessive disorders have been associated with mutations in the RECQL4 gene: Rothmund-Thomson, RAPADILINO, and Baller-Gerold syndromes, thus making RECQL4 unique within the RecQ family of DNA helicases. To date, however, the molecular function of RECQL4 and the possible cellular pathways in which it is involved remain poorly understood. Here, we present an overview of recent findings in connection with RECQL4 and try to highlight different directions the field could head, helping to clarify the role of RECQL4 in preventing tumorigenesis and maintenance of genome integrity in humans. Received 31 October 2006; received after revision 4 January 2007; accepted 5 February 2007     

过冷纯熔体中晶体生长平界面的稳定性分析

具有匀速运动平直界面的一维凝固系统,一经扰动其界面将不再为平面。Mullins-Sekerka在假定扰动波长远远小于热扩散长度与液固界面满足局部平衡条件的基础上,推出了M-S色散关系。在界面上也存在着动力学的作用,即界面的稳定性也依赖于动力过冷。文章在界面上考虑动力学影响,应用渐近分析理论继续分析过冷纯熔体液固界面的稳定性。结果表明,非快速凝固系统的液固界面不会绝对稳定。     

车辆操稳性的虚拟样机技术研究

文章利用ADAMS/Car软件建立前/后悬架、转向系、前/后轮以及车身等子系统模型;在此基础上进行整车操纵稳定性仿真,选取了稳态回转试验、角脉冲输入瞬态响应及转向回正试验,仿真试验结果表明了虚拟样机技术的可行性及所建模型的正确性,实现了在虚拟试验平台上分析汽车的操纵稳定性。     

一类非线性发展方程差分法的稳定性

研究了用差分法求解自治的发展方程时稳定性和收敛性这两个基本概念之间的联系,利用计算时间的有限性和紧致性,在可解集为开集的条件下,得出方程解的邻近也可解的结论.当近似方法同时具备收敛性和稳定性时,方程解必然具备逐点Lipschitz条件.方程解的邻近如果可解并具备逐点Lipschitz条件,则差分法收敛必有稳定界存在,从而差分格式收敛性保证其稳定性,因此可以放弃线性这一重要条件.     

导引头稳定平台离散时间预设性能控制

针对现有离散时间预设性能控制方法对滑模趋近律依赖度高、抖振缺陷明显的难题,通过创建一种摆脱了滑模控制的设计新框架,为拦截弹导引头稳定平台提出了一种离散时间预设性能控制新方法。首先,设计一种离散时间性能函数对跟踪误差的收敛轨迹进行包络约束;然后,定义一种离散时间转换误差并将其用于构造一种新颖的反馈函数;设计离散时间控制律对新开发的反馈函数而不是转换误差进行镇定,不仅保证了所有跟踪误差均具有期望的预设性能,还摆脱了控制算法对滑模趋近律的依赖性,从根本上解决了控制抖振难题;最后,通过数值对比仿真验证了所提方法的有效性与优势。