基于余弦相似度的改进ORB匹配算法

针对ORB(oriented FAST and rotated BRIEF)在匹配多相似区域图像时误匹配率高的问题,提出一种基于余弦相似度的改进ORB算法.该算法首先通过汉明距离(Hamming distance)最近邻匹配,计算匹配特征向量的余弦相似度;其次通过梯度计算法计算余弦相似度的最优阈值范围;然后将汉明距离高...     

氧化石墨烯复合膜的制备及其在水体中脱除染料的性能

为同时提高氧化石墨烯(GO)膜的稳定性及分离性能,以戊二醛为交联剂,引入聚乙烯醇(PVA)和二氧化钛(TiO2),采用真空辅助过滤法制备了TiO2/GO/PVA复合膜,通过SEM、TEM、FTIR、XRD对复合膜的形态结构进行表征,并通过接触角仪、错流装置和超声实验测试膜对染料的分离性能及稳定性.结果表明:随着TiO2...     

High-sensitivity photonic crystal fiber sensor based on surface plasmon resonance

In this paper, we propose a photonic crystal fiber (PCF) sensor based on the surface plasmonic resonance (SPR) effect for simultaneous temperature and refractive index (RI) measurement. The coupling characteristics and sensing performance of the sensor are analyzed using the full vector finite element method (FEM). The sensor provides two channels for independent measurement of RI and temperature. When operating independently, channel I supports y-polarized light with a sensitivity of up to 7 000 nm/RIU for detecting RI, while channel II supports x-polarized light with a sensitivity of up to 16 nm/°C for detecting temperature. Additionally, we investigate the influence of gold layer thickness on the sensing performance to optimize the sensor.     

Flaw sizing with distance,probe displacement,size (DDS) diagrams

Echo drop is one of the commonly used methods of flaw sizing in ultrasonic NDT. This method, which can measure flaw dimensions due to changes in echo amplitude observed during ultrasonic probe displacement, has some limitations with regard to defect geometry and dimensions. The results described show the relationships of probe displacement, measured with echo drops of 6, 10 and 20 dB, on ultrasonic probe-flaw distance and flaw size. The DDS diagrams provide information about the usefulness of echo-drop methods for sizing totally embedded and side-wall breaking defects with the help of probes generating divergent beams of longitudinal waves.     

基于三维霍尔传感器的钢轨缺陷漏磁检测系统

为检测钢轨顶面的剥离、裂纹等缺陷,设计基于三维霍尔传感器的钢轨缺陷漏磁检测系统.采用钕铁硼环形永磁体对钢轨检测区域进行垂直于钢轨方向的励磁,并将检测车的车轮轮轴同时作为励磁回路的磁扼,由ARM单片机采集三维霍尔传感器检测的缺陷漏磁场数据.在钢轨顶面人工制作一系列横向矩形凹坑缺陷样本,检测结果表明:钢轨缺陷三维漏磁检测系...     

季铵型改性壳聚糖的制备及其在兔毛织物抗菌整理中的应用

以三乙胺和环氧氯丙烷为原料,合成醚化剂3-氯-2-羟丙基三乙基氯化铵。以甲壳素为原料通过醚化反应合成了季铵型甲壳素（CCT）,再经脱乙酰得到季铵型阳离子改性壳聚糖（CCTS）。采用红外光谱（FTIR）、核磁碳谱（¹³C NMR）对其化学结构进行了表征,运用黏度法和分光光度法测定了黏均分子量和溶解性等理化性能。采用最小抑菌法对CCTS的抗菌活性进行了测定,得到其对大肠杆菌的最低有效抑菌浓度（MIC）为0.2g/L,优于天然壳聚糖的MIC值。以柠檬酸为交联剂、次磷酸钠为催化剂,用CCTS对兔毛织物进行抑菌整理,考察织物经整理的抑菌效果和耐洗性。经5次洗涤后结果表明,CCTS对大肠杆菌的抑菌率达99.9%以上,抑菌率高于CCT和天然壳聚糖,是一种针对动物毛织物良好的天然高分子长效抑菌整理剂。     

Egg shell waste as an activation agent for the manufacture of porous carbon

Egg shell waste was used as an activation agent directly for the manufacture of a biomass-derived porous carbon,which possessed a surface area of 626 m~2·g~(-1) and was rich in nitrogen, sulfur and oxygen functionalities. The activation mechanism was proposed, and the carbon showed its potential to act as an adsorbent for the adsorptive removal of various contaminants from both aqueous and non-aqueous solutions, possessing maximum adsorption capacities of 195.9, 185.1, 125.5 and 44.6 mg·g~(-1) for sulfamethoxazole, methyl orange, diclofenac sodium and dibenzothiophene, respectively. Through the utilization of egg shell waste as a sustainable activation agent, this work may help to make the widely applied biomass-derived porous carbons more economical and ecological.     

Graphite powder coated polyurethane sponge hollow tube as a high-efficiency and cost-effective oil-removal materials for continuous oil collection from water surface

In this study, the cost-effective graphite powder (GPd)-coated polyurethane (PGPd-PU) sponge hollow tube (PGPd-PUHT) was prepared for high-efficient continuous oil removal, the hydrophobicity-superoleophilicity PGPd-PU sponge was fabricated through a simple dip-coating method, which dipping PU sponge into GPd dispersion and drying, then coating polydimethylsiloxane (PDMS) on sponge skeleton, as-prepared sponge could selectively absorb a variety of oils up to 34 times of its own weight for dimethyl sulfoxide (DMSO). The PGPd-PUHT was prepared via wrapping PGPd-PU sponge on porous tubular support. The obtained PGPd-PUHT could continuously collect various types of oils from water surface with flux as high as 1.52 kL/m²h, and excellent separation efficiency (up to 97.7%) for toluene, as well as remarkable reusability. Moreover, a continuous floating oil collection device based on PGPd-PUHT was designed which showed excellent floating oil collection ability. In addition, our strategy possesses the advantages of low cost, simple preparation, highly efficient, and easily scale-up, showing a great potential for dealing with practical oil spill remediation. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020 , 137, 48921.     

Phase transition and interface evolution of Al2O3/ZrO2 particles in plasma-sprayed coatings

Alumina and zirconia ceramic particles exhibit high hardness and excellent wear resistance at high temperature, and hence are used as ceramic reinforcement phases in some plasma sprayed coatings. In this study, the interface evolution of a zirconia/alumina eutectic ceramic and the phase transition of zirconia in a plasma-sprayed coating were investigated. Scanning electron microscopy and transmission electron microscopy combined with focused-ion beam and energy dispersive X-ray were used to analyze the microstructure and composition of the ceramic interface. The results showed that the eutectic ceramic particles consisted of alumina (outer) and columnar zirconia (inner) before and after the plasma spraying process. The inner zirconia part showed the martensitic transformation of t-type zirconia to stripe-like m-type zirconia. After the plasma spraying, the interface between alumina and zirconia changed significantly, which formed a new oxide layer. The phase transition mechanism in the ceramic particle and oxide layer formation mechanism at the alumina/zirconia interface were investigated.     

絮体表面形态对膜污染预测的影响

现有对混凝-膜过滤过程中膜污染的预测分析,一般采用XDLVO理论对光滑界面的作用能进行计算,但混凝絮体表面形态会对预测结果产生较大的影响。利用正弦波球体模型对粗糙腐殖酸(HA)絮体表面进行模拟,并通过表面元素积分法(SEI)结合XDLVO理论与复合辛普森规则,对不同粗糙程度的混凝絮体与聚偏氟乙烯(PVDF)膜的界面作用能进行量化模拟;并将结果与传统XDLVO理论模拟的光滑界面作用能进行了比较。实验结果表明,该模型适用于混凝-膜过滤体系中絮体界面作用能的模拟,同时在模拟过程中,由于粗糙度的不同会导致界面作用能在数值上存在1~2个数量级的差异;并且粗糙的絮体较完全光滑的絮体与膜污染趋势的拟合程度更高,即引入絮体表面形态对利用絮体与膜界面间相互作用能表征膜污染趋势的置信度更高。