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991.
992.
一种基于 PLC 和 HMI 的层压控制系统 总被引:1,自引:0,他引:1
为实现对铝基覆铜板层压工艺中两个关键参数温度和压力的自动控制,在采用分级蓄能层压工艺的基础上,设计一种基于三菱PLC和台达HMI的自动化层压控制系统。介绍控制系统的硬件组成、控制流程、HMI的软件设计及PID参数的整定。 相似文献
993.
随着国内预拌混凝土行业的发展,混凝土企业高层越来越意识到搅拌站信息化管理的必要性,各种混凝土搅拌站ERP软件在国内得到了迅速的发展,通过这种软件的信息化管理,后台数据库每天都会产生大量的生产数据。为了避免搅拌站之间的恶性竞争,混凝土行业协会和政府部门需要对某个区域乃至整个行业的搅拌站的生产运营情况有实时的了解,以便对其进行监管,最终促进行业的公平竞争。本文结合国内混凝土行业自身的特点,阐述了混凝土行业海量数据协同的总体构想和数学模型,之后从多维度论述了基于JCS多级缓存的海量数据协同模块的设计,最后,采用Socket的方式最终实现了Server端与Client端的一对多的数据通信。 相似文献
994.
995.
996.
Zheng Peng Si‐Dong Li Mao‐Fang Huang Kui Xu Chen Wang Pu‐Wang Li Xiao‐Guang Chen 《应用聚合物科学杂志》2002,85(14):2952-2955
The thermal degradations of methyl methacrylate‐graft‐natural rubber (MG) at different heating rates (B) in nitrogen were studied by thermogravimetric analysis. The results indicate that the thermal degradation of MG in nitrogen is a one‐step reaction. The degradation temperatures increase along with the increment of heating rates. The temperature of initial degradation (T0) is 0.448B + 362.4°C, the temperature at maximum degradation rate, that is, the peak temperature on a differential thermogravimetric curve (Tp) is 0.545B + 380.7°C, and the temperature of final degradation (Tf) is 0.476B + 409.4°C. The degradation rate at Tp is not affected by B, and its average value is 48.9%; the degradation rate at Tf is not affected by B either, and its average value is 99.3%. The reaction order (n) is 2.1 and is not affected by B. The reaction activation energy (E) and the frequency factor (A) increase along with B, and the apparent reaction activation energy (E0) is 254.6 kJ/mol. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 85: 2952–2955, 2002 相似文献
997.
The lifetime and performance of a direct methanol fuel cell (DMFC) were investigated to understand the correlation between the structure of catalysts/membrane and cell performance versus time. The cell polarization and performance curves were obtained during the DMFC operation with the time. The catalysts and Nafion® membrane of the membrane electrode assembly (MEA) from the lifetime test were comprehensively examined by XRD, HRTEM, FTIR and Raman spectroscopy techniques. The results revealed that there was significant performance degradation during the first 200 h operation; while the degradation was slowing down between 200 and 704 h operation. The degradation became worse after 1002 h operation. The increases of the catalyst particle size from both anode and cathode catalysts were observed after the DMFC lifetime test. The changes of microstructure, surface composition, the interfacial structure of the MEA, and the aging of Nafion® under the DMFC lifetime tests were also observed. 相似文献
998.
The preparation of very hydrophobic poly(vinylidene fluoride) (PVDF) membranes was explored by using two methods. The first one was the modified phase inversion method using a water/N,N‐dimethylacetamide (DMAc) mixture instead of pure water as a soft precipitation bath. The second method was a precipitation‐bath free method, that is, the PVDF/DMAc casting solution underwent gelation in the open air instead of being immersed into a precipitation bath. The morphology of the surface and cross section of the membranes was investigated by using scanning electron microscopy (SEM). It was found that the membranes exhibited certain micro‐ and nanoscale hierarchical roughness on the surface, which brought about an enhanced hydrophobicity of the membrane. The contact angle (CA) of the samples obtained by the second method was as high as 150° with water. The conventional phase inversion method preparing PVDF porous membrane using pure water as precipitation bath usually results in an asymmetric membrane with a dense skin layer having a CA close to that of a smooth PVDF surface. The modified approach avoided the formation of a skin‐layer and resulted in a porous and highly hydrophobic surface of PVDF. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 98: 1358–1363, 2005 相似文献
999.
以单质碘为催化剂,通过丁醛和乙二醇反应合成了丁醛乙二醇缩醛。探讨了单质碘对缩酮反应的催化活性,较系统地研究了醛醇物质的量比、催化剂用量和反应时间诸因素对产品收率的影响。实验表明:在n(丁醛)∶n(乙二醇)=1∶1.5、催化剂用量为反应物料总质量的0.4%、带水剂环己烷的用量为8mL和反应时间45min的优化条件下,丁醛乙二醇缩醛的收率可达77.6%. 相似文献
1000.
1 INTRODUCTION Since Cu-ZSM-5 was reported as an effective catalyst for the selective catalytic reduction (SCR) of NO by hydrocarbons in the presence of excess oxygen, the SCR of NOx has received much attention as a kind of potential technology for cleaning NOx in various oxygen-rich exhausts of diesel engine, lean burning gasoline engine and gas engine. Although a number of catalysts have been tested, to date, it still seems to be difficult to find a catalyst that is completely suit… 相似文献