随机非线性和部分转移概率未知时马尔科夫系统的H1控制

研究上述系统时: 1) 利用了非线性的概率分布信息; 2) 利用了转移概率中已知部分和未知部分的关系. 利用李雅普诺夫泛函方法和线性矩阵不等式方法, 本文得到了使得系统随机稳定的充分条件并得到了相应的反馈控制增益. 文中最后给出的例子表明了所建立模型和分析方法的有效性.     

基于80 C196KC单片机的Smith伺服控制器

讨论全数字伺服系统中的时间滞后，通过Smith预估控制器补偿系统中的时间滞后，提出一种应用80C196KC单片机的宽范围、高精度调速的控制方案及算法。对于非滞后系统采用Smith伺服控制器，可以简化系统、提高性能指标。     

金属皂类热稳定剂对RPVC流变性能的影响

采用Brabender转矩流变仪，分析并探讨了硬酯酸钡（BaSt2）、硬酯酸铅（PbSt2）、硬酯酸钙（CaSt2）、硬酯酸锌（ZnSt2）4种硬酯酸金属皂类热稳定剂以及复配BaSt2／PbSt2热稳定剂对硬质聚氯乙烯（RPVC）流变性能的影响。结果表明，BaSt2，CaSt2能够促进RPVC的塑化，而PbSt2和ZnSt2却推迟RPVC的塑化；在复配BaSt2／PbSt2稳定剂体系中，随着BaSt2比例的增大，塑化时间缩短，但BaSt2与PbSt2按分子数1：1比率时，RPVC熔体粘度增幅较大。     

系统控制单元数据存储更新算法探讨

系统控制单元的有限存储空间被系统运行数据写满时,新产生的数据就需替换旧数据完成更新。通过采用逐条替换法、分块替换法、间歇删除法和抢断删除法,比较替换过程中最少存储数据的数量和实时性的滞后时间,找出一种最优的数据更新方法。试验结果表明,抢断删除替换算法更能快速有效实时完成数据的更新。     

Optimal periodic forcing of nonlinear chemical processes for performance improvements

Unsteady-state periodic operations can improve the optimal steady-state performance of nonlinear chemical processes. To examine if the optimal periodic operation is proper and to obtain the optimal forcing functions subject to various control and state constraints it is suggested in this paper to convert the problems into a form which is suitable for constrained nonlinear programming. The adopted numerical optimization method is based on employing the control parametrization technique and is thus capable of dealing with the problem of multiple input forcings and obtaining optimal forcing functions and/or parameters while subject to general constraints. Besides, it provides information about to what extent the process performance can be improved by adopting the optimal periodic control.     

砂带用酚醛树脂粘合剂的合成研究

本文讨论了砂带用酚醛树脂粘合剂的合成工艺和条件。研究了反应投料比，温度及增塑剂对反应过程和树脂性能的影响。磨削性能证明合成树脂性能良好。     

FAST LINEAR ESTIMATION METHODS FOR VECTOR AUTOREGRESSIVE MOVING-AVERAGE MODELS

Abstract. Three linear methods for estimating parameter values of vector auto-regressive moving-average (VARMA) models which are in general at least an order of magnitude faster than maximum likelihood estimation are developed in this paper. Simulation results for different model structures with varying numbers of component series and observations suggest that the accuracy of these procedures is in most cases comparable with maximum likelihood estimation. Procedures for estimating parameter standard error are also discussed and used for identification of nonzero elements in the VARMA polynomial structures. These methods can also be used to establish the order of the VARMA structure. We note, however, that the primary purpose of these estimates is to generate initial estimates for the nonzero parameters in order to reduce subsequent computational time of more efficient estimation procedures such as exact maximum likelihood.     

安全苛刻系统自动化测试的形式化语义模型

安全苛刻系统的可信性需求典型而迫切,其可信性评估和验证具有测试依赖性.安全苛刻系统一般是复杂系统,手工测试实际上不可行,发展自动化测试手段是必然趋势.针对安全苛刻系统测试过程自动化中存在的高阶协同、实时和时序性,以Ambient演算、CCS演算、论域理论等为基础,给出测试过程的高阶协同定义,建立一种层次化演算模型,为测试过程提供一种信息化和自动化手段.模型通过对被测产品、测试设备与测试任务的抽象与组织,给出安全苛刻系统测试过程自动化的工作模式.最后,通过扩展标记转换系统定义,给出高阶协同行为的收敛性和正确性的证明,论证了模型的可计算性,验证了安全苛刻系统测试的可自动化.模型已应用于航天器的自动化测试中,并成为航天器测试行为的日常工作规范.     

Electrochemical anticorrosion performance evaluation of Al2O3 coatings deposited by MOCVD on an industrial brass substrate

Alumina (Al₂O₃) coatings of different thickness were deposited on OT59 brass substrate (BS) using the metal organic chemical vapour deposition (MOCVD) technique to evaluate the corrosion performance by EIS measurements. The used precursor was dimethyl-aluminium-isopropoxide. Electrochemical characterizations of the deposited films were performed in a standard very aggressive acidic solution (aerated 1N H₂SO₄ at 25 °C up to 168 h of immersion time) by means of direct current method (Tafel curves) and electrochemical impedance spectroscopy (EIS). The Rutherford backscattering spectroscopy (RBS) indicated that the films are very pure with the correct Al₂O₃ stoichiometry, while the IR absorption spectra showed that the films did not contain any OH groups. The surface film morphology was investigated by atomic force microscopy (AFM) and displayed a globular texture. The films were very smooth, with a maximum root mean square roughness, for example, of 14 nm for a 0.96 μm thick coating. The EIS data confirmed, as expected, that a 2.40 μm Al₂O₃ layer ensures the best corrosion protection after 168 h of immersion in the very acidic environment used.     

钛基体化学镀镍及其耐蚀性能

采用化学镀在钛基体上制备Ni-P合金镀层.研究了活化时间、镀液pH值、热处理温度及时间对镀层的影响.用动电位极化曲线法比较镀层的耐均匀腐蚀性能,并用X-射线衍射仪和扫描电子显微镜分别研究镀层结构和表面形貌.结果表明,以HF为主剂的活化液,时间60 s,pH值4.8～5.2的活化工艺以及250 ℃、保温2 h的热处理为最佳工艺.镀层具有较高的耐蚀性能,属于非晶和微晶组成的混晶结构.借助于正交试验,确定了最佳工艺.