8毫米波段固体微波锁相源

介绍一种8毫米(Ka)波段固体微波锁相源,采用数字环路锁相技术,实现了从5MHz到Ka波段频率稳定度的良好传递。整个锁相源的秒级频率稳定度为10~(-9)量级,长期频率稳定度为10~(-7)量级,能够可靠入锁的频率范围大于120MHz,输出功率大于30mW。     

Determination of volatile carboxylic acids (C1–C5i) and lactic acid in aqueous acid extracts of silage by high performance liquid chromatography

A simple isocratic h.p.l.c. technique was developed for the simultaneous quantitative analysis of lactic, formic, acetic, propionic, isobutyric, <i>n</i>-butyric and isovaleric acids in aqueous acid extracts of silage. An Aminex HPX-87H strong cation exchange resin column at 41°C, 0.0025M H<sub>2</sub>SO<sub>4</sub> mobile phase and ultraviolet detector at 210 nm were utilised. Estimated recoveries of acids added to silage ranged from 98.2 to 103.5%.     

数据库连接策略优化方法

目的是结合邮政物流信息系统的开发 ,实现高效、安全的数据库连接管理 ,方法为在对数据库连接进行详细分析的基础上 ,利用资源池设计模式 ,实现数据库连接池 ,实现连接的高效、安全的复用 ,提出并实现了一个高效的数据库连接管理策略 ,使得开发高性能的数据库应用变得相对容易 .对于事务和多线程下的数据库连接这两个难点问题进行了深入的剖析 ,并给出了一个基于设计模式的解决方案 ,由此 ,本文结合邮政物流信息系统的开发 ,给出了一个具有一定普遍意义的基本的连接管理框架 ,使得高效、安全的复用数据库连接成为可能     

基于数字图像处理技术的测量工件平行度的新方法

本文主要介绍了一种测量管状件轴线平行度的新方法。该方法采用激光准直技术结合数字图像处理技术来进行管状件轴类工件的两轴或多轴平行度的测量。其优点是无损检测、测量精度较高、易于实现整个测量过程的自动化和智能化。     

东北电网联络线功率频率控制方案研究

通过对互联电网内各控制区域几种有功功率调整控制策略的配合分析,并结合东北电网运行实际情况,提出了适合于东北电网运行情况的控制策略。     

Analysis of discrete-time piecewise affine and hybrid systems

In this paper, we present various algorithms both for stability and performance analysis of discrete-time piece-wise affine (PWA) systems. For stability, different classes of Lyapunov functions are considered and it is shown how to compute them through linear matrix inequalities that take into account the switching structure of the systems. We also show that the continuity of the Lyapunov function is not required in discrete time. Moreover, the tradeoff between the degree of conservativeness and computational requirements is discussed. Finally, by using arguments from the dissipativity theory for nonlinear systems, we generalize our approach to analyze the l₂-gain of PWA systems.     

土地利用遥感动态监测多时相数据管理

土地利用遥感动态监测是一个长期的、持续的过程 ,如何对不同阶段的原始数据、结果数据进行有效地管理是一个迫切需要解决的问题 .应用时态地理信息系统 (TemporalGIS ,TGIS)技术 ,设计了一个实用的时态数据模型及数据存储结构 ,该模型充分考虑了数据的空间、时间、属性三要素 .最后应用该模型思想初步实现了对研究区域数据的有效管理     

基于Agent的低速链路QoS技术

在低速链路上提供端到端有QoS保证的服务是当前亟待解决的问题。论文参考IETF建议,采用头标压缩、分组分段和排队技术,给出一个基于移动代理技术的完整解决方案。每个Agent不仅能独立完成一定的任务,而且能相互配合,可在一定程度上解决现有低速链路QoS技术的某些不足。     

时滞系统的一种低阶l_1-控制

研究了离散时滞系统的一种低阶 l1-控制问题 .得到了系统可实现状态反馈及输出反馈 l1-控制的充分条件 ,并将其转化为线性矩阵不等式 (LMI)形式 ,给出了 l1-控制的显式表达形式 .文中的处理不是转化为无穷维受限优化问题 ,而是优化 l1-范数的一上界 .尽管得到的是次优 l1-控制律 ,但由于它具有确定的结构 ,故分析和设计过程十分简单     

Decentralized networked control of discrete‐time systems with local networks

This paper considers discrete‐time large‐scale networked control systems with multiple local communication networks connecting sensors, controllers, and actuators. The local networks operate asynchronously and independently of each other in the presence of variable sampling intervals, transmission delays, and scheduling protocols (from sensors to controllers). The time‐delay approach that was recently suggested to decentralized stabilization of large‐scale networked systems in the continuous time is extended to <img alt="urn:x-wiley:rnc:media:rnc3862:rnc3862-math-0001" class="section_image" src="//wol-prod-cdn.literatumonline.com/cms/attachment/103a525c-31d1-4adf-a191-c071b5a28cd9/rnc3862-math-0001.png"> decentralized control in the discrete time. An appropriate Lyapunov‐Krasovskii method is presented that leads to efficient LMI conditions for the exponential stability and <i>l</i><sub>2</sub>‐gain analysis of the closed loop large‐scale system. Differences from the continuous‐time results are discussed. A numerical example of decentralized control of 2 coupled cart‐pendulum systems illustrates the efficiency of the results.