Bottom‐Up Preparation of Fully sp2‐Bonded Porous Carbons with High Photoactivities

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.     

Practical evaluation of encrypted traffic classification based on a combined method of entropy estimation and neural networks

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.     

基于视觉分析的智能拾网球机器人研究

针对目前智能拾网球效率低的问题,本文给出一种基于图像处理算法和蚁群算法的智能拾取网球机器人,该机器人结构为笼式结构,系统通过摄像头实时采集图像信息,使用WIFI传送到PC机,PC机利用图像处理算法从场景中提取所有网球及每个网球的坐标点,使用蚁群算法对提取的网球坐标点进行路径规划得到拾球最短路径;通过摄像头实时采集的图片数据提取拾球机器人的实时位置及方位,控制机器人按规划好的路径对网球进行顺序拾取。     

使用双区块链的防伪溯源系统

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。     

功率超声在线数字化检测方法

检测功率超声设备的负载阻抗为分析和研究负载阻抗对超声设备的影响提供依据.本文提出一种方法,在大功率驱动超声设备正常工作的同时,通过数字信号采集及后续的FFT变换和频域特性分析,得到超声设备在工作状态下的负载阻抗信息.通过实验验证,此方法可以较好地检测超声设备的带负载情况.     

假肢接受腔阳模刀位插补方法及其误差比较

在分析假肢接受腔阳模数控加工特点的基础上,针对三坐标数控铣加工,讨论了直接法、退刀法、矢量法三种典型刀位计算方法在接受腔阳模加工中的应用,分析了加工误差的来源及其分布,并给出了逼近误差和刀具补偿误差的计算方法。通过加工实验,验证了三种刀位计算方法的有效性和误差分析方法的正确性。实验结果表明:直接法简单,但加工误差大,只适合于粗加工;退刀法复杂,加工误差大,不适用;矢量法复杂,误差小,适用于阳模加工刀位的插补计算。     

贵州茶叶专业合作社发展困境及应对策略分析

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。     

Selective adsorption of p-chloronitrobenzene from aqueous mixture of p-chloronitrobenzene and o-chloronitrobenzene using HZSM-5 zeolite

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.     

剪力墙配筋计算和施工图生成

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     

K11通用型防水涂料的探讨

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。