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91.
Wenyong Ming Shuai Bi Yinghang Zhang Kaijin Yu Chenbao Lu Xiaobin Fu Feng Qiu Ping Liu Yuezeng Su Fan Zhang 《Advanced functional materials》2019,29(14)
Porous carbons, possessing exceptional stability, high surface area, and electric conductivity, are broadly used as superior adsorbent, supporter, or electrode material for environmental protection, industrial catalysis, and energy storage and conversion. The construction of such kinds of materials with designable structures and properties will extremely extend their potential applications, but remains a huge synthetic challenge. Herein, a bottom‐up approach is presented to synthesize one type of fully sp2 carbon–bonded frameworks by transition metal–catalyzed cross‐coupling of different polyphenylenes with electron‐withdrawing 9,9′‐bifluorenylidene (9,9′‐BF) through its 2,7‐position. The resulting porous polymeric carbons exhibit substantial semiconducting properties, such as strong light‐harvesting capabilities in the visible light region, likely due to their π‐extended backbones with donor–acceptor characters. Their electronic and porous structures can be finely tuned via the polyphenylene spacers. The intriguing properties allow these porous carbons to efficiently catalyze dye degradation under visible light or even natural sunlight with high reusability. Meanwhile, associated with their intrinsic structures, these porous carbons also exhibit highly selective degradation activities toward different dyes. In particular, the photodegradation mechanism involving oxygen and electron is elucidated for the first time for such kinds of materials, related to the presence of specific 9,9′‐BF units in their π‐conjugated skeletons. 相似文献
92.
Encrypted traffic classification plays a vital role in cybersecurity as network traffic encryption becomes prevalent. First, we briefly introduce three traffic encryption mechanisms: IPsec, SSL/TLS, and SRTP. After evaluating the performances of support vector machine, random forest, naïve Bayes, and logistic regression for traffic classification, we propose the combined approach of entropy estimation and artificial neural networks. First, network traffic is classified as encrypted or plaintext with entropy estimation. Encrypted traffic is then further classified using neural networks. We propose using traffic packet’s sizes, packet's inter‐arrival time, and direction as the neural network's input. Our combined approach was evaluated with the dataset obtained from the Canadian Institute for Cybersecurity. Results show an improved precision (from 1 to 7 percentage points), and some application classification metrics improved nearly by 30 percentage points. 相似文献
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区块链是一种随着比特币等加密货币而兴起的一种类似于非关系型的分布式存储数据库,本文利用区块链分布式存储、去信任化和不可篡改的特性设计了一个基于区块链技术的防伪溯源系统(Traceability System Using Public and Private Blockchain,TSPPB)。TSPPB使用公有链和私有链两套区块链,该溯源系统能够确保获得的溯源信息的真实可靠不可篡改并解决传统产品溯源系统存在的产品标签复制、滥发和产品质量问题相关责任人及问题环节定位困难的问题。在确保溯源信息安全性并解决传统溯源系统隐患的同时,TSPPB还能够高效且保持低成本的运行。 相似文献
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合作社是推动贵州茶产业发展的有效组织之一。运用案例分析法对凌峰茶叶专业合作社进行案例分析,得出其发展茶产业的影响因素、面临的发展困境等问题,基于结论,提出促进茶产业发展的应对策略。 相似文献
98.
The selective adsorption of p-chloronitrobenzene (p-CNB) using zeolite as the adsorbent from an aqueous mixture containing p-CNB and o-chloronitrobenzene (o-CNB) was investigated. The maximum adsorption amounts of p-CNB in HZSM-5 zeolite were found to be approximately 4 molecules per unit cell (mol/uc) at all adsorption temperatures investigated. The maximum adsorption amounts of o-CNB in HZSM-5 zeolite were, however, markedly lower than those of p-CNB at different adsorption temperatures. Diffusion results revealed that the diffusivity of p-CNB at 300K was about 100 times higher than that of o-CNB in HZSM-5 zeolite. The remarkable difference in the adsorption amounts and diffusivities between p-CNB and o-CNB resulted in separation factors of 463.6, 96.8 and 21.9 for p-CNB at 278, 300 and 323 K, respectively, indicating a selective adsorption of p-CNB in HZSM-5 zeolite from the aqueous mixture of p- and o-CNB. 相似文献
99.
剪力墙配筋计算和施工图生成 总被引:1,自引:0,他引:1
介绍了钢筋混凝土剪力墙构件设计时进行配筋、选筋、双向弯曲验算以及施工图自动生成的方法 ,这些算法已在广厦结构CAD系统和广厦三维墙元分析程序SSW软件中实现 ,并广泛应用于民用建筑的剪力墙设计和施工图生成 ,实践表明算法是有效的 相似文献
100.
K11通用型防水涂料的探讨 总被引:1,自引:0,他引:1
探讨了目前我国南方防水材料市场迅速发展的K11通用型防水涂料的配方设计原理、性能要求及其防水机理。介绍了K11通用型防水涂料的应用领域,为更好地发挥材料性能,对该防水涂料的施工要求进行规范,并指出了一些使用注意事项。最后展望其广阔市场前景。 相似文献