气相色谱结合化学计量在核桃油、菜籽油掺伪混合物含量判别分析中的应用

目的：识别核桃油中同时掺入多种其他植物油的多元掺伪。方法：采用气相色谱技术分析核桃油、菜籽油掺伪混合物中脂肪酸含量,结合化学计量方法对气相色谱数据进行建模,并对不同比例核桃油、菜籽油混合物进行判别分析。结果：主成分分析法（PCA）能快速鉴别出纯核桃油和掺伪核桃油,并在一定程度上反映样本的掺伪比例;Bayes判别分析将83.33%的样品归入正确的分类;偏最小二乘判别分析法（PLS-DA）的判别准确率达87.50%;基于BP神经网络模型的判别分析,其训练集的正确率为84.21%,测试集的正确率为80.00%;基于遗传算法优化支持向量机（SVM-ga）的判别分析,其训练集和测试集的正确率均为100%。结论：多种分析模型均能不同程度地识别核桃油、菜籽油掺伪比例,其中SVM-ga模型的预测精度最佳。     

Ultra-Damping Composites Enhanced by Yolk–Shell Piezoelectric Damping Mechanism

High-performance damping materials are significant toward reducing vibration and maintaining stability for industrial applications. Herein, a yolk–shell piezoelectric damping mechanism is reported, which can enhance mechanical energy dissipation and improve damping capability. With the addition of yolk–shell particles and carbon nanotube (CNT) conductive network, damping properties of various resin matrices are enhanced with the energy dissipation path of mechanical to electrical to heat energy. Particularly, the peak loss factor of epoxy composites reaches 1.91 and tan δ area increases by 25.72% at 20 °C. The results prove the general applicability of yolk–shell piezoelectric damping mechanism. Besides, the novel damping materials also exhibit excellent flexibility, stretchability, and resilience, offering a promising application toward damping coating, indicating broad scope of application in transportation and sophisticated electronics, etc.     

圆柱壳弹性波超材料分级排列的带隙拓宽方法研究

圆柱壳弹性波超材料的弯曲波带隙拓宽问题限制其满足实际工程中的宽频隔振要求,针对该问题,本文首先研究了基于局域共振机理的圆柱壳弹性波超材料弯曲波带隙特点,研究局域谐振器质量和弹簧劲度系数的关系,然后将周期分级排列的组合方式应用于圆柱壳类弹性波超材料的带隙拓宽中,并利用有限元法进行能带结构和振动传输特性计算.研究结果显示：该方法可实现弯曲波带隙的拓宽;利用组合法构建的轴向周期分级排列圆柱壳弹性波超材料可实现705-1226Hz频率范围内弯曲波的高效衰减,带隙拓宽至分别为单一谐振器的2.55倍,这表明该方法在宽频减振方面具有明显优势,应用前景广阔.     

基于改进深度学习的风机油污识别

针对风机设备油液渗漏影响风机正常运行亟需解决的对风机设备油污的识别问题,提出了一种基于改进深度学习的风机油污检测方法。基于深度学习在目标检测中的应用特点,对目标检测网络YOLOv5n（You Only Look Once v5n）进行改进,将原网络中的非极大抑制（Non Maximum Suppression,NMS）替换为Soft-NMS,降低了网络的误检率,添加CA (Coordinate Attention)注意力机制,增强了模型对目标的定位能力,改进原网络损失函数为α-IoU（Alpha- Intersection over Union）损失函数,提高了边界框检测的准确度。实验结果表明:模型平均精度提升了8.1%,查全率提高了19.1%,网络推理速度提高了28.6%。改进后的模型能准确检测风机油污,有效解决了风机实际运行中油液渗漏所带来的问题。     

我国石油天然气管材再制造发展战略研究

管材作为石油天然气勘探、开采、运输的重要材料,由于腐蚀、磨损、结垢造成的管材失效,而被大量废弃,在油田堆积如山,造成了巨大的资源浪费和环境污染。本文分析石油天然气废旧管材的处理现状及存在的问题,利用先进的再制造技术对管材再制造的经济效益、社会效益和环境效益进行了论证,提出自主创新的石油天然气管材再制造产业模式及发展建议,为我国石油天然气行业降本增效和节能减排目标的实现提供新理念、新技术,为促进石油天然气行业循环经济的建设提供决策建议。     

Formulation and performance evaluation of a novel coconut oil–based metalworking fluid

Metalworking fluid (MWF) supplies a film of lubricant to abate friction, acts as a cooling media to rebate induced heat, and prevents metal pick-ups by flushing away the chips. Hence a liquid used as a cutting fluid reduces wear on the tool, reduces the energy consumption, and produces a better surface quality on the work piece. This paper describes the formulation of a novel water-soluble MWF and its performance evaluation during straight turning and end milling experiments carried out with AISI 304 stainless steel, mild steel, and cast iron as work piece materials. The MWF was prepared by mixing water with white coconut oil as the base oil and food-grade additives as surfactants. Viscosity, pH value, and biodegradability were measured and compared with a commercially available non-vegetable oil–based MWF. The surface roughness and tool surface temperature were measured throughout the machining experiments, and better performances were observed with the coconut oil–based MWF. Tool tip geometry and flank wear for straight turning machining operation were identified by observing scanning electron microscope (SEM) images.     

Plasmon‐Enhanced Spectroscopies with Shell‐Isolated Nanoparticles

Shell‐isolated nanoparticle‐enhanced Raman spectroscopy (SHINERS), due to its versatility, has been able to break the long‐term limitations of the material‐ and substrate‐specific generalities in the traditional field of surface‐enhanced Raman spectroscopy. With a shell‐isolated work principle, this method provides an opportunity to investigate successfully in surface, biological systems, energetic materials, and environmental sciences. Both the shell material and core morphology are being improved continuously to meet the requirements in diverse systems, such as the electrochemical studies at single crystal electrode surfaces, in situ monitoring of photoinduced reaction processes, practical applications in energy conversion and storage, inspections in food safety, and the surface‐enhanced fluorescence. Predictably, the concept of shell‐isolated nanoparticle‐enhancement could be expanded to the wider range for the performance of plasmon‐enhanced spectral modifications.