湿法氧化锌种类和用量对天然橡胶性能的影响

研究湿法氧化锌种类和用量对天然橡胶(NR)性能的影响。结果表明:与添加普通氧化锌的胶料相比,对于未填充炭黑NR体系,减半用量的湿法氧化锌混炼胶的焦烧时间和t90较短,Fmax较大;硫化胶的定伸应力、拉伸强度和剪切模量(G′)较大,拉断伸长率、损耗模量(G″)和损耗因子(tanδ)较小。对于填充炭黑NR体系,减半用量的湿法氧化锌混炼胶的门尼粘度、G′和G″较大,tanδ较小,焦烧时间和t90较短,Fmax较大;硫化胶的密度稍低,硬度和定伸应力较大,耐老化性能较好,玻璃化温度较低,tanδ较小,其他物理性能变化不大。湿法氧化锌FF的性能优于湿法氧化锌HR。     

含天青石、石膏白云岩混合溶蚀特征研究

以亚洲第一长白云岩洞穴——贵州省遵义市绥阳双河洞地区的白云岩为研究对象,根据白云岩中石膏(或硬石膏)的存在可加速白云石溶解的理论,考虑双河洞洞穴中同时存在天青石(SrSO_4)与石膏(CaSO_4)岩层,溶解后形成混合溶液,可能会加速白云岩的溶蚀。白云岩在自然条件下常混有杂质,为了实验的准确性,直接采用白云石进行实验。在静态条件下进行白云石在含天青石和石膏的不同含量溶液中混合溶蚀的模拟实验,研究在常温酸性和中性条件下,双河洞地区的地下水以及地表水对白云岩溶蚀过程的影响。结果表明,根据地下水以及地表水中Ca/Sr比例不同以及pH值的不同,在离子强度以及同离子效应的影响下,Ca/Sr比例直接影响白云石的溶蚀率,且生成的过多沉淀吸附在白云石的溶蚀孔隙中,会导致实验反应减缓。该研究为解释绥阳双河洞白云岩洞穴的成因具有一定的指导意义。     

WDM-PON技术在5G前传承载中的应用研究

前传在5G(第五代通信技术)承载网性能与网络优势发挥上起到越来越重要的支撑作用。文章通过各类技术在5G前传承载中的应用研究,充分对比差异及优缺点,得出C-RAN(集中化无线接入网)方式下高速WDM-PON(波分复用无源光网络)作为前传技术具备建网快捷、建设成本低、运营维护简便等多种优势,为WDM-PON技术在5G前传网络中的规模部署提供有力支撑,也能更快推动WDM-PON产业链的成熟和发展。     

液压阻尼孔的宽温度范围流动特性试验研究

研制一种适合对各种液压孔口或缝隙进行高低温流体力学试验的新型试验装置，运用该装置对具有不同几何参数的液压阻尼孔进行在-50~80℃宽温度范围内的流动特性试验，研究以普通抗磨液压油HM46和低温抗凝减振器油TITAN SAF 5045为工质及其温度变化时对液压阻尼孔流量-压力特性曲线、幂指数和流量系数的影响，研究表明，在低温条件下，液压阻尼孔的流量系数均因油液黏度增大、流动性变差而呈线性下降的趋势，从宏观上看，HM46通过液压阻尼孔时的流动稳定性较差，其对应流量系数的下降幅度明显大于TITAN SAF 5045对应的下降幅度，厚壁小孔流量系数的下降幅度明显大于薄壁小孔对应的下降幅度。研究所获得的新型试验装置、试验数据分析方法和具体理论公式为深入研究和优化现代液压元件在宽温度范围内的动态性能提供新型试验平台与理论基础。     

Modelling the cross‐contamination of Listeria monocytogenes in pork during bowl chopping

This study has developed a predictive model for the cross‐contamination of pork by Listeria monocytogenes during bowl chopping. The transfer rates of L. monocytogenes were measured in sixteen chopping scenarios based on practical work. Meanwhile, contaminated bowl chopper was cleaned with either a dry rag (DR), warm water (WW) or 70% ethanol + water (EW), respectively. It was showed that significant differences (P < 0.05) were observed among the three cleaning methods on the reduction of L. monocytogenes, the greatest log reduction being achieved by EW. Moreover, the model introduced by a previous study, predicting cross‐contamination of L. monocytogenes during meat slicing, was improved and validated in this study. Verification results showed that the improved model was acceptable for predicting L. monocytogenes cross‐contamination during pork chopping with coefficients of determination (R² > 0.82), accuracy factors (A_f < 1.44), bias factors (B_f < 1.42), and root mean square error (RMSE < 0.99). Furthermore, the modified model might provide an effective tool for assessing the risk of the cross‐contamination of meat products.     

WSe2/rGO hybrid structure: A stable and efficient catalyst for hydrogen evolution reaction

The number of exposed active sites in a catalyst plays a key role in determining its catalytic performance. However, the aggregation effect in nanostructured catalysts causes much less reactive sites exposed. In this paper, we report a novel structure of WSe₂/rGO with highly exposed WSe₂ active edge sites by uniformly imbedding the rGO between each WSe₂ nanosheets. With the introduction of rGO, the electron transport property of the WSe₂/rGO hybrid structure has also been enhanced. The structure and composition of the samples were investigated by the X-ray diffraction, X-ray photoelectron spectroscopy, scanning electron microscopy and transmission electron microscopy. Our electrochemical characterizations confirm that the WSe₂/rGO hybrid structure exhibits enhanced electrochemical catalytic performance with a Tafel slop of 85 mV/dec for HER, much smaller than that of the pure WSe₂.     

梁子湖水环境主要污染因子研究

研究了梁子湖水环境主要污染因子。分别采用综合污染指数法和卡尔森综合营养指数法对梁子湖入湖口、中心梁子岛、东梁子湖湖心、出湖口等监测点的水质状况和营养状态进行评价。结果表明,梁子湖的出湖口水质状况最好,入湖口最差;全湖处于中营养状态;总磷、总氮、COD_(Cr)、COD_(Mn)、BOD_5为梁子湖主要污染因子;梁子湖主要污染物的来源主要包括外源污染物的流入、区域内面源污染等。     

光伏用电致发光缺陷检测仪空间分辨率的量化评估

针对光伏用电致发光缺陷检测仪空间分辨率目视判定重复性、准确性差,并且难以量化等问题,提出一套基于卷积神经网络模型的空间分辨率量化评估方法。参照相关标准JJF(闽)1088-2018,采取不同的拍摄条件拍摄并切割出空间分辨率线对图像,对图像进行人工分类。设计卷积神经网络结构,采用卷积层、池化层和全连接层结构,并使用已分类完成的空间分辨率线对图像对模型进行训练。最终使用测试集对模型进行评估,结果表明,模型在测试集上的判别正确率达到99.2%。该方法满足使用要求,可取代目视判别,提高了光伏用电致发光缺陷检测仪空间分辨率判定的准确性与重复性,并为其量化提出了新的解决思路。由于太阳电池片用光致发光缺陷检测仪与光伏用电致发光缺陷检测仪的成像方式类似,该方法可兼容太阳电池片光致发光检测仪的性能评估。     

Processing capability and QoE driven optimized computation offloading scheme in vehicular fog based F-RAN

World Wide Web - The Fog Computing was proposed to extend the computing task to the network edge in lots of Internet of Things (IoT) scenario, such as Internet of Vehicle (IoV). However, the...     

Spatial Relationships of Water Resources with Energy Consumption at Coal Mining Operations in China

Mine Water and the Environment - The spatial characterization and regional differences of water use in China’s coal mines were investigated based on a high spatial resolution mine site...