基于区块链技术的查询索引认证方法

为了实时快捷地在视频流上生成模式索引,提出了基于区块链的索引认证方案,用于面向事件的实时监控视频查询.通过边缘节点和雾节点之间的加密安全信道来保护索引数据,以提升智能监控系统的安全性.首先,通过在嵌入式边缘设备上执行检测和跟踪任务,面向事件的监控服务通过处理输入帧来提取特征信息;然后,实时索引服务为每帧生成唯一性索引,以防止对图像的恶意修改;最后,将帧索引输入区块链网络,并通过基于去中心化智能合约的认证机制进行验证.实验结果证明了本文方案的可行性和有效性.其总开销非常低,适用于实时监控视频查询的应用.     

卷积神经网络下的高分二号卫星影像道路提取

本文针对深度神经网络对高分二号遥感影像道路提取时细节信息丢失较多、道路周围环境考虑不充分等情况,在已有的研究成果上,提出一种基于全卷积神经网络遥感影像道路提取的改进方案.方案创新研究了全卷积神经网络的算法原理,将预调色后的高分二号影像按一定尺寸分幅输出,将输出图像及标签对应输入于以全卷积神经网络为基础的改进网络,通过结...     

计时电流法检测食品中亚硝酸盐的含量

目的 建立计时电流法精确测定食品中亚硝酸盐含量。方法 将钴纳米粒子、氧化石墨烯以及聚吡咯聚沉于电极表面, 构建检验亚硝酸根的电化学传感器, 对检测条件进行优化, 确定了计时电流法检测亚硝酸盐的线性范围, 对检测方法的特异性进行验证后利用优化后的检测条件对样品进行检测。结果 制备出一种检测亚硝酸盐的电化学传感器, 其最优电位确定为0.85 V, 最优pH为8.0, 最优沉积时间为300 s, 干扰物质多巴胺、抗坏血酸、尿酸对于亚硝酸盐的检测结果影响较小, 且对样品进行检测发现, 所建立的方法准确度较高。结论 制备出检验亚硝酸根的电化学传感器, 该系统稳定性好、精确度高, 适用于食品中亚硝酸盐含量的测定。     

Sorption of nitrate onto amine-crosslinked wheat straw: characteristics, column sorption and desorption properties

The nitrate removal process was evaluated using a fixed-bed column packed with amine-crosslinked wheat straw (AC-WS). Column sorption and desorption characteristics of nitrate were studied extensively. Solid-state (13)C NMR and zeta potential analysis validated the existence of crosslinked amine groups in AC-WS. Raman shift of the nitrate peaks suggested the electrostatic attraction between the adsorbed ions and positively charged amine sites. The column sorption capacity (q(ed)) of the AC-WS for nitrate was 87.27 mg g(-1) in comparison with the raw WS of 0.57 mg g(-1). Nitrate sorption in column was affected by bed height, influent nitrate concentration, flow rate and pH, and of all these, influent pH demonstrated an essential effect on the performance of the column. In addition, desorption and dynamic elution tests were repeated for several cycles, with high desorption rate and slight losses in its initial column sorption capacity.     

Synthesis of titania microspheres with hierarchical structures and high photocatalytic activity by using nonanoic acid as the structure-directing agent

The titania, as the heterogeneous photocatalyst, has attracted much attention in attempts to eliminate pollutants, especially organic compounds in water and air. In this study, the titania microspheres with hierarchical structures were prepared by a combined sol–gel and solvothermal method. The X-ray powder diffraction (XRD) result indicated that the synthesized titania microspheres were of anatase phase. Field-emission scanning electron microscope (FESEM) and high-resolution transmission electron microscope (HRTEM) showed that the microspheres with well-dispersity had an average diameter of 651 nm and were composed of nanoparticles with about 20 nm in diameter. The Brunauer–Emmett–Teller (BET) results showed that the microspheres possessed high surface areas and lots of mesopores. Further study indicated that the synthesized titania microspheres exhibited high photocatalytic activity and had an important advantage over the commercial P25.     

超声波检测中的小波降噪

论文介绍了小波分析在检测信号处理中的应用,并通过对超声波的传播进行分析得到超声波信号的噪声产生原因,构建了含噪回波信号的数学模型。对原始信号采用小波分解重构降噪、硬阈值降噪、软阈值降噪三种方法进行信号处理,并对三种方法进行比较。     

Dynamic morphology instability in epitaxial ZnO/AZO (aluminum-doped ZnO) core–shell nanowires

Misfit strain relaxation-induced morphology instability is usually observed in epitaxial heterostructures at high temperatures. In this paper, we report that this morphology instability can occur even at room temperature in epitaxial ZnO/AZO (Al-doped ZnO) core–shell nanowires (NWs). As a result, densely distributed ZnO nanodots (NDs) were self-assembled on the NWs. The growth of NDs was slowed down during aging owing to the gradually reduced misfit strain. The final size and shape of the NDs were highly depended on the shell thickness and the doping ratio. It was proved that the morphology stability could be improved by surface passivation, thinning the shell thickness, or lowering the doping ratio. The results may provide instructive suggestions for the reliable design in strain and surface engineering of nanomaterials.