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目前,OPC技术在工厂级的监测与控制系统中获得了广泛的应用,但是在远程监控系统SCADA中的应用则要困难很多。本文结合Internet技术,提出了基于Web服务器的远程监控系统的设计思路和体系架构方法。通过Visual Basic语言编程制作了OPC客户端的COM组件,然后将COM组件嵌入到Web网页中,采用ActiveX、ASP、HTML等相关的Web技术就可以实现数据的Web发布和远程工业实时数据监控,从而实现了管理层通过标准的浏览器就可以达到异地管理工业生产现场的目的。该套监控程序已经成功应用于辽宁省教育厅高等学校科学研究项目《工业现场智能化设备的嵌入式软件构件平台研究》中,并且即将应用于化学、石油、钢铁等工业控制领域。 相似文献
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Guo-jun Li Zhan-ru Sun Chun-huan Chen Xue-jun Cui Rui-ming Ren 《Materials Letters》2007,61(17):3585-3588
A novel chemical method for the preparation of nanocrystalline MgAl2O4 spinel powders has been developed in this paper. The mixed magnesium-aluminum hydroxide precipitates were initially formed in a three-dimensional space network microarea. After being calcined at above 700 °C, the nanocrystalline MgAl2O4 spinel powders were obtained. The precursor and as-calcined powders were characterized using TGA-DTA, XRD and TEM. The MgAl2O4 spinel powders calcined at 850 °C for 2 h are of narrow distribution, little agglomeration and small particle size of ∼ 24 nm. The reason for the synthesis of high-quality powders was explained. 相似文献
96.
Dealloying of Au-Ag thin films with a composition gradient: Influence on morphology of nanoporous Au 总被引:1,自引:0,他引:1
Nanoporous Au can be formed by dealloying Au-Ag alloys and, depending on the initial alloy composition, produce a variety of microstructural features. We investigated a wide compositional range and found three regimes, based on initial Au content, that yield varying degrees of dealloying in thin films. Between 22 and 26 at.% Au, dealloying produces nearly pure Au with an open nanoporous structure. However, above 36 at.% Au, only the grain boundaries dealloy, leaving islands of retained Au-Ag alloy. For intermediate compositions, a transitional microstructure results, with final Ag concentration ranging from 50 at.% down to 4 at.%. Film cracking was observed after dealloying, and lower initial Au content correlated with a higher degree of cracking and a higher pore fraction. 相似文献
97.
小型蓄冷复合空调器同普通空调器相比,节约了能源和费用,经济性能更高.从小型蓄冷复合空调系统的节能机理、节能效果进行比较与分析. 相似文献
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This article addresses the problem of controller design for networked control systems over digital communication. The systems under consideration are stabilised via state feedback, where the effects of sampled signal, state quantisation, network-induced delay and packet dropout are considered. The proposed delay-dependent stability criteria are formulated in the form of a linear matrix inequality, which ensure asymptotic stability and a prescribed H ∞ performance level for networked control systems with admissible uncertainties. Maximum allowable delay bound of networked control systems is obtained by solving a convex optimisation problem. Furthermore, a numerical example is given to illustrate the effectiveness of the main result. 相似文献
100.
Weimin Gao Lingxue Kong John M. Long Peter D. Hodgson 《Journal of Materials Processing Technology》2009,209(1):497-505
The mass (e.g. carbon) transfer coefficient at a workpiece surface is an important kinetic factor to control the heat treatment process of the workpiece and to evaluate heat treatment equipment. The coefficient can be calculated from the carbon concentration at the surface of a sample carburized in a carburizing furnace for a given time. Two common measurement methods which use a thin plate and employ a component as samples respectively are evaluated and compared for sensitivity and uncertainty. The comparison shows that the use of a component produces higher measurement precision and also has the advantage in measuring the carbon transfer coefficients at different treated positions. This method is then extended and discussed methodologically. Also two equations are proposed to calculate the carbon transfer coefficient and its uncertainty, respectively. This method is also applied to measure the carbon transfer coefficient in a fluidized bed heat treatment furnace. 相似文献