Simultaneously improved solid particle erosion resistant and strength of graphene nanoplates/carbon nanotube enhanced thermoplastic polyurethane films

Up to now, it is a major challenge to protect leading edge of the blades from solid particle erosion. Herein, we propose a structure optimization strategy to fabricate non-woven (NW) enhanced thermoplastic polyurethane nanocomposite films (thermoplastic polyurethane [TPU] - NW@G/C_x) with “sandwich - like” structure by hot pressing technology. TPU NW/graphene nanoplates/carbon nanotube (NW@G/C_x) interlayer film were first fabricated by spraying method. Then the interlayer film was laminated between TPU films to fabricate nanocomposite films. Such prepared TPU - NW@G/C_x film shows excellent solid particle erosion resistance and high-tensile strength. For example, the “steel-and-mortar” structure of NW fabric in TPU film results in high-tensile strength of 45 MPa and storage modulus of 21.2 MPa for TPU - NW@G/C_1.0, increasing by 25% and 171% compared with original TPU film (35 MPa, 8 MPa), respectively. In addition, compared with pure TPU film, the “sandwich - like” structure endows TPU - NW@G/C_1.2 with excellent solid particle erosion resistance and the thermal conductivity (0.251 W/m·K). These superior properties extends application of the TPU - NW@G/C_x film on wind turbine blades.     

Synergistic improvement of mechanical and thermal properties in epoxy composites via polyimide microspheres

Achieving synergetic improvements of mechanical strength, toughness, and thermal stability of epoxy resin has been a crucial but very challenging issue. Herein, to explore a new solution for circumventing this issue, polyimide microspheres were successfully prepared through the inverse nonaqueous emulsion process, and the structure, size distribution and morphologies of polyimide (PI) microspheres were comprehensively investigated. Then the PI microspheres were incorporated in epoxy resin matrix to systematically investigate the mechanical and thermal properties of obtained epoxy/PI microspheres composites. It was found that the PI microspheres can not only enhance the mechanical strength of epoxy resin, but also significantly improve the toughness. Specially, the epoxy-based composites containing 3 wt% PI microspheres exhibit a 47% increase in tensile strength, while the G_IC and Charpy impact strength increase by 106% and 200%, respectively. The toughing mechanism of epoxy/PI microspheres composites was discussed. Moreover, the PI microspheres can also endow the epoxy resin with excellent thermal stability and heat resistance. Thus, this work may open a new opportunity to synergistically enhance the mechanical and thermal properties of epoxy-based composites and may also give some valuable inspiration for the rational design of other high-performance thermosetting composites.     

Enzymatic degradability and release properties of graphene oxide/silk fibroin nanocomposite films

The structure evolution of silk fibroin (SF) in the nanocomposite films with graphene oxide (GO) was investigated and related to the enzymatic degradability and release property. The interaction with GO was found to induce conformation transition of SF from random coil to β-sheet. However, the surface binding constrained the rearrangement of the silk chains, leading to a decrease of β-sheet when GO content was more than 1.0%. The crystal structure of SF played a key role in the degradation of GO/SF composites. The preferential degradation of the hydrophilic blocks resulted in a faster degradation of SF films with higher β-sheet content. The addition of GO to SF matrix led to a slower release and a reduction of the burst release of RhB, the model compound. The release profile was well fitted to the Rigter–Peppas equation, from which the characteristic constant decreased and the diffusional exponent increased with increasing GO content but quickly leveled off when GO content was more than 1.0%. Degradation of the composites had little influence on the characteristic constant of RhB release, however, led to an increased diffusional exponent, which was more evident for the composites with higher β-sheet content.     

Hydrogen bonding induced enhancement for constructing anisotropic sugarcane composite hydrogels

Anisotropic hydrogels are appealing with their merits of similar biochemical and structural properties to the biological tissues. However, the mechanical properties of current anisotropic hydrogels need to be further improved. Herein, three kinds of novel anisotropic poly(2-hydroxyethyl methacrylate) (pHEMA), poly(acrylamide) (pAM), and poly(acrylamide-co-acrylic acid) (p[AM-co-AA]) sugarcane composite hydrogels were prepared successfully by filling the hydrogel monomer precursor into porous aligned sugarcane nanofibers network and then performing subsequent free radical polymerization. The hydrogel matrix and sugarcane nanofibers network were combined closely together through hydrogen bonding interaction. The anisotropic sugarcane composite hydrogels exhibit good flexibility and elastic recovery properties upon encountering mechanical crimping and twisting. In typical case, the as-prepared pHEMA sugarcane composite hydrogel can exhibit high anisotropic tensile strength of 2.37 and 0.54 MPa, while differential tear strength of 0.36 and 0.78 N/mm, along the parallel and vertical nanofibers directions. Finally, anisotropic lubrication behaviors were found and investigated systematically for those three kinds of sugarcane composite hydrogels when water was used as lubricant. Our current work proposes a simple and universal strategy for developing bioinspired anisotropic functional composite matters such as artificial skin, flexible sensor, and cartilage lubrication materials.     

钢桥梁智能涂装生产线建设及应用研究

相比较汽车等行业,我国钢桥梁涂装施工机械化、智能化水平还处于空白。本文以温州瓯江北口大桥钢桁梁桥为依托,结合钢桁梁节段结构特点,研究、开发了适合钢桁梁桥涂装施工的顶部天车喷砂机器人、底部轮式喷砂机器人、悬臂喷漆机器人等机械化装备,通过反复工艺试验,选取得出最佳工艺参数;通过 5G网络和视频监控将喷砂系统、喷漆系统进行智能集成,形成了智能监控系统,实现了涂装全过程机械化和智能化,并成功应用在温州瓯江北口大桥钢桁梁涂装施工中,取得了良好的经济效益和社会效益,在行业内具有广泛推广价值。     

基于双旋杯工艺的水性 3C1B复合涂层的研发

在 3C1B（三涂一烘）的工艺下,通过树脂、助溶剂、颜料的合理搭配制备了一款水性双组分中涂和一款水性双组分底色漆,中涂采用旋杯喷涂,底色漆采用两遍旋杯的喷涂方式,该配套组合能够满足产品对于多种性能的要求。同时探究了在上述工艺条件下,漆膜厚度变化以及漆雾对漆膜外观的影响,结合抗紫外穿透测试,找出了施工的最佳膜厚。结果表明：随着中涂和底色漆膜厚的增加, DOI下降, LW和 SW上升,且漆雾的存在会导致外观质量下降;中涂推荐施工膜厚为 12~15 μm,色漆总施工膜厚为 11~16 μm。     

配电网单相接地故障特征分析软件设计

我国35 kV及以下配电网大多采用小电流接地方式,运行方式下发生的故障中单相接地故障占70％～80％.当前已有的单相接地故障诊断软件大多无法适应多种Windows操作系统,并且在功能方面较为单一,未形成完备的系统,不能满足需求.在提取接地故障的小波能量比、小波重构系数方差和暂态功率方向三种暂态特征的基础上,设计一款功能完备的单相接地故障特征分析软件,并且利用Pyinstaller库将软件封装为.exe格式的可执行文件.设计软件具有丰富的人机交互接口,能够完成小波分解、波形展示、故障诊断模型训练以及故障诊断等功能,实现了在各种Windows系统下运行并进行单相接地故障数据分析的功能.     

风电机组健康状态预测中异常数据在线清洗

风电机组数据采集与监视控制系统(SCADA)运行数据中含有大量异常数据,对风电机组健康状态预测影响严重,为此针对实测风速-功率、转速-功率数据,提出一种异常数据在线清洗方法.由于机组性能退化过程中数据特征趋于复杂,基于经验Copula-互信息(ECMI)选择关键特征参量作为数据清洗对象,并基于Copula建立置信等效功率区间描述其非线性与不确定性.针对置信边界外的堆积点和离群点,结合其时序特征与密度分布建立Copula数据清洗模型(Copula-TFDD),依次进行在线清洗.最后,基于实际数据与人工模拟数据分析模型的精度、运算效率以及对机组健康状态预测的影响表明,Copula-TFDD能准确并实时地识别各类异常数据,有效提升风电机组健康状态预测的性能.     

基于深度学习增强的LSD杆塔倾斜度检测

杆塔的倾倒会对整个电网产生严重的破坏并威胁周围居民的生命安全,电力巡检无人机利用计算机视觉对杆塔进行巡检既节省了人力资源又显著地提高了电网的巡检效率.为了国网巡检人员在杆塔倾倒前及时得到预警,对电力巡检无人机中的基于计算机视觉的杆塔倾斜检测算法进行了研究,设计了一种基于YOLOv3的深度神经网络结合LSD线段提取方法对杆塔的倾斜进行检测.利用在山西电网无人机实际巡检的杆塔图片制作杆塔的VOC2007数据集并利用YOLOv3神经网络对杆塔进行目标检测,并将检测后得到的Bounding box根据网络训练后的mIOU参数进行微调后作为LSD检测的ROI.接着,该方法在ROI中将检测的线段进行过滤和融合,根据杆塔特点进行杆塔的二次识别.最后利用得到的杆塔外边线做出该方向上的杆塔中线并计算杆塔在该方向的倾斜度.该文中实验利用山西国网电力公司提供的数据进行验证,结果表明,杆塔的倾斜检测效果在各种拍摄高度和背景干扰下都较为精确,杆塔目标的正确识别率达到97％,倾斜度检测平均误差小于0.85°.     

六分量大阻力复合式结构天平研制与应用

着陆巡视器和探月返回舱等短钝体风洞试验模型具有更大的阻力测量范围和更短的长度尺寸,为了提高该类模型在风 洞试验中的测量精准度,研制了一种新型复合式结构大阻力六分量应变天平。 与传统串联式结构天平相比,复合式结构天平结 构紧凑而阻力承载能力更强,能够完全安装于模型内部从而减少温度对天平测量精准度的影响;数值模拟结果表明,复合式结 构天平的平均应变、灵敏度、强度等能够满足风洞试验要求;复合式结构天平静态校准综合校准准度优于 0. 21%,满足国军标相 关技术指标。