MPE-YOLOv5:面向边缘计算的轻量化YOLOv5手势识别算法

针对边缘设备计算和存储能力差的问题，本文对传统YOLOv5模型中用于特征提取的主干网络CSPDarkNet53进行轻量化处理，提出了一种轻量化MPE-YOLOv5手势识别算法，以实现模型在低功耗边缘设备上的部署；针对轻量化模型提取特征较少而导致的难以识别大尺度变换目标和微小目标问题，对M-YOLOv5网络设计添加有效通道注意力机制(efficient channel attention, ECA),以缓解因特征通道减少而导致的高层特征信息丢失的问题；同时增加针对微小目标的检测层，提高对微小目标手势的敏感度；并选用EIoU作为预测锚框的损失函数，以提高模型的定位精度。本文在自制数据集和NUS-Ⅱ公共数据集上验证了MPE-YOLOv5算法有效性，并将MPE-YOLOv5算法与轻量化后的M-YOLOv5算法和原始的YOLOv5算法在自制数据集上进行了对比实验。实验结果表明，改进算法的模型参数量、模型大小和计算复杂度分别是原算法的21.16%、25.33%和27.33%,平均精度可达97.2%;与轻量化模型M-YOLOv5相比，MPE-YOLOv5能够在保持原来效率的同时，使平均精度提升8.7...     

支链化聚铵盐及其在压裂和酸化作业中的应用

制备了支链化聚铵盐系列化合物,评价了其在清水、胍胶液和盐酸溶液中对粘土膨胀的抑制作用,并对微观结构进行了分析。结果显示:在最佳制备条件下0.5%BPM-7溶液中90min时粘土的线性膨胀率为50.0%;BPM-7与胍胶的配伍性良好,能够强化胍胶液的抑制性,在酸液中也有较强的粘土稳定作用。支链化聚铵盐可通过离子交换取代粘土中原有的金属阳离子进入粘土层间,从而抑制水分子水化分散粘土,保持粘土层间距和颗粒的结构。作为粘土稳定剂应用于某气田酸化作业,能有效保护储层,作业后产气量显著提升。     

Study of using aluminum hypophosphite as a flame retardant for low‐density polyethylene

Aluminum hypophosphite (AHP) was first used to improve the flame retardance of low‐density polyethylene (LDPE). The flame‐retardant properties of LDPE composites were investigated by the limiting oxygen index, vertical burning test (UL‐94), microscale combustion calorimetry, and cone calorimeter tests. The results showed that the incorporation of AHP could improve the flame retardancy of LDPE dramatically, the limiting oxygen index of LDPE containing 50 phr AHP reached 27.5%, and the UL‐94 could pass V‐0 rating. The cone calorimeter test results indicated that PP/AHP composite exhibited superior performance, and the heat release rate and the total heat release of composites were significantly reduced. In addition, the strength of the char was improved with the load of AHP increased. The structure of the char was researched by Fourier transform infrared spectrometry (FTIR) and scanning electron microscope‐energy dispersive spectrometer, and the results revealed that AHP promoted the formation of compact char layer. The TG‐FTIR analyses proved that AHP could react with LDPE to reduce the production of olefin in gas phase. Moreover, the structure of P–O–C was found, and the effective mechanism of AHP in LDPE composites was also hypothesized in this work.     

DN-YOLOv5的金属双极板表面缺陷检测算法

为解决氢燃料电池中金属双极板表面缺陷尺寸小，缺陷对比不明显、种类多造成的难以检测，易误检漏检以及缺陷检测模型复杂度太大难以部署等问题，提出一种改进版的金属双极板缺陷检测算法DN-YOLOv5,来探究缺陷检测在冲压成形的金属双极板视觉检测工作台场景下进行快速精准检测的可行性，从而实现智能检测，提升检测效率。本研究着重于修改YOLOv5主干网络Backbone部分，添加网络中模块数量，加入NAM注意力机制和使用深度可分离卷积模块来替代原来CSP/CBS主干网络卷积模块，并引入SIoU对损失函数重新进行了定义，极大的提升了主干网络的轻量化程度。结果表明，本算法的map@0.5可达0.988,每秒检测传输帧率为9.98,模型参数量降低了52.13%,在测试集75张缺陷图像中真检率达到了99.74%。该方法在保证模型较高检测率的同时，显著降低了模型复杂度和参数计算量。此外，该算法结合新的检测尺度设计特征融合网络，提升网络的小目标、多目标检测能力。该算法具有良好的稳定性和鲁棒性，综合性能较好，满足部署移动端场景进行缺陷检测的轻量化需求。     

Carbonaceous-TiO2 nanomaterials for photocatalytic degradation of pollutants: A review

Semiconductor photocatalysis is one of most appealing and attractive technologies, which has been directly utilized to harvest solar energy for energy and environmental applications. Titanium dioxide (TiO₂) has been proved to be leading semiconductor photocatalyst for the degradation of pollutants. However, it suffers from low photocatalytic activity under visible light activation because of its intrinsic wide band gap. Various strategies have been developed to enhance TiO₂ efficiency in the visible light region. Among them TiO₂ modification with carbonaceous nanomaterials is very effective route for excellent photocatalytic activity. This critical review aims to present recent progress in the design and synthesis of carbonaceous-TiO₂ photocatalysts, covering carbon doping, activated carbon, fullerenes, carbon nanotubes and graphene. Moreover, proposed mechanisms of enhancement, effect of synthesis routes, demonstrations of performance and applications reported in literature are reviewed. Ongoing challenges and possible new directions are outlined.     

Synergistic Flame-retardant Effect and Mechanism of Nitrogen–Phosphorus-Containing Compounds for Glass Fiber-reinforced Polyamide 66

The system based on aluminum phosphinate (OP) and melamine polyphosphate was applied in flame-retardant glass fiber-reinforced polyamide 66. From a qualitative and quantitative point of view, the incorporation of OP played a positive role in obtaining the homodisperse of flame-retardant particles throughout the composites. A two-step cooling mode during the degradation process was established to play an effective role in absorbing heat to retard the flame spread rate and provide enough time for barrier generation. In condensed phase, the cross-linked structure formed in residue promoted the construction of the high-quality barrier layer.     

分析无机絮凝剂混凝机理中的力化学因素

以混凝机理为基础,建立了无机絮凝剂的混凝物理模型。通过混凝物理模型与无机絮凝剂的双电层压缩机理相结合,研究无机絮凝剂和投加时的稀释比例不同产生的效果,指出无机絮凝剂的混凝机理中存在流体力化学效应。     

两亲聚合物对湿法磷酸的助滤性能及机理研究

以实验室自制单体A、丙烯酰胺(AM)、二甲基二烯丙基氯化铵(DMDAAC)为原料,过硫酸盐氧化还原体系为引发剂,采用水溶液共聚法合成一种用于湿法磷酸助滤的两亲聚合物PADA-10。对所得聚合物的助滤性能进行研究,结果表明:磷酸料浆体系中加入PADA-10后,过滤速度提高了约4.3倍,滤饼水分降低了约10.8%。对PADA-10助滤机理的初步探究结果表明:PADA-10能在一定pH值范围内中和磷石膏表面电荷,使磷石膏微晶絮凝成团,添加PADA-10后滤饼的孔隙率增加;同时,PADA-10能增强磷石膏颗粒的疏水性,使磷酸滤液表面张力降低了5.2 mN/m,磷石膏表面接触角增大了3.4°。