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81.
Acetylene as a reducing agent for the selective catalytic reduction (C2H2-SCR) of NO in the presence of excess oxygen on various Ce-exchanged zeolites was investigated for the first time. Under the conditions of 1600 ppm NO, 800 ppm C2H2, and 9.95 % O2 in He, the Ce-H-ZSM-5 (Si/Al=25) catalyst shows about 83% NO conversion to N2 at the temperatures ranged from 300 to 350 °C. It is followed by the other zeolites in the activity order of Ce-H-Y (Si/Al=2.5), Ce-H-_ (Si/A1=20∼30), and Ce-H-SAPO (Si/Al=34), Ce-H-5A (Si/Al=12). Almost no NO conversion was obtained over Ce-Na-ZSM-5 (Si/Al=25) and Na-ZSM-5 (Si/Al=25) catalyst samples. The Conversion of NO to N2 increased with O2 concentration in the range of 0.1 ∼ 9.95% over the CeH-ZSM-5 (Si/Al=25) catalyst. It is suggested that O2 plays an important role in the C2H2-SCR of NO reaction, by oxidizing NO to NO2 on acid sites in assistant with cerium species of the catalyst. A large amount of CO, which seems to be in proportion with the NO conversion to N2, was produced. Long-term experiments up to 56 h combined with a excursion of the reaction temperature up to 650 °C over the Ce-H-ZSM-5 (Si/A1=25) confirmed the catalyst’s durable performance under the reaction conditions. It is found that the de-NOx activity of Ce-H-ZSM-5 catalyst can be enhanced by the presence of 50 ppm of sulfur dioxide in the dry-feed reaction conditions. 相似文献
82.
Hardware security has become more and more important in current information security architecture. Recently collected reports have shown that there may have been considerable hardware attacks prepared for possible military usage from all over the world. Due to the intrinsic difference from software security, hardware security has some special features and challenges. In order to guarantee hardware security, academia has proposed the concept of trusted integrated circuits, which aims at a secure circulation of IC design, manufacture and chip using. This paper reviews the main problems of trusted integrated circuits, and concludes four key domains of the trusted IC, namely the trusted IC design, trusted manufacture, trusted IP protection, and trusted chip authentication. The main challenges in those domains are also analyzed based on the current known techniques. Finally, the main limitations of the current techniques and possible future trends are discussed. 相似文献
83.
网络化雷达在战场上可以构成全方位、立体化、多层次的战斗体系,因
此对欺骗式干扰对抗具有很大的优越性。本文首先简要介绍了网络化雷达概念,并分析了其
抗干扰优势。根据网络化雷达融合结构不同,将现有协同抗干扰方法分为数据级融合抗欺骗
式干扰和信号级融合抗欺骗式干扰两大类,其中,数据级融合方法进一步分类为点迹关联和
航迹关联两类。本文对各类方法进行了详细介绍,在此基础上,比较分析了数据级融合和信
号级融合两类方法的抗干扰性能及算法复杂度,为抗干扰措施的选择提供依据。最后,针对
现有方法中存在的问题,对网络化雷达协同抗欺骗式干扰的发展趋势进行展望,指出下一步
的研究方向。 相似文献
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简述了我国塑料助剂生产现状、市场供需及发展方向,“十五”期间我国塑料助剂工业发展势头强劲,目前已基本满足我国塑料工业的发展需求,但是在品种和产品质量等方面与国外先进水平相比仍有较大的差距。提出了提高我国塑料助剂国际市场竞争力的措施。 相似文献
90.
Jun-Hai Lv Mei Zhang Min Guo Wen-Chao Li Xi-Dong Wang 《International Journal of Applied Ceramic Technology》2007,4(6):571-577
NaNbO3 , KNbO3 , and K x Na(1− x ) NbO3 powders were successfully prepared by the hydrothermal method. The phase of the products was identified to be orthorhombic structure by X-ray diffraction (XRD) technique, and the XRD results revealed that the x value of the K x Na(1− x ) NbO3 gradually increased with the increase in the ratio of K+ to Na+ in alkaline solution. The morphology and the microstructure were investigated by scanning electron microscopy, energy-dispersive spectroscopy, and transmission electron microscopy, and the results indicated that the ratio of K+ to Na+ in the solution had a great effect on the morphology and the size of products. Na0.5 K0.5 NbO3 with morphotropic phase boundary composition could be synthesized when the molar ratio of K+ to Na+ was between 4:1 and 6:1 in the solution. A possible formation mechanism of the K x Na(1− x ) NbO3 crystal was also proposed based on the experimental results. 相似文献