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Epidemic spreading has been studied for a long time and is currently focused on the spreading of multiple pathogens,especially in multiplex networks. However, little attention has been paid to the case where the mutual influence between different pathogens comes from a fraction of epidemic propagators, such as bisexual people in two separated groups of heterosexual and homosexual people. We here study this topic by presenting a network model of two layers connected by impulsive links, in contrast to the persistent links in each layer. We let each layer have a distinct pathogen and their interactive infection is implemented by a fraction of propagators jumping between the corresponding pairs of nodes in the two layers. By this model we show that(i) the propagators take the key role to transmit pathogens from one layer to the other,which significantly influences the stabilized epidemics;(ii) the epidemic thresholds will be changed by the propagators;and(iii) a reverse-feeding effect can be expected when the infective rate is smaller than its threshold of isolated spreading.A theoretical analysis is presented to explain the numerical results. 相似文献
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有关调和油快速准确定量检测的研究对于调和油质量控制具有重要意义。以往对调和油定量分析的研究大多集中于二元、三元和四元调和油,对更高元数调和油的研究很少,难以满足调和油检测需求。该研究的目的是探讨近红外光谱结合化学计量学对五元调和油中各单组分油进行定量分析的可行性。由玉米油、大豆油、稻米油、葵花油和芝麻油配制成51个五元调和油样品,并采集各样品12 000~4 000 cm-1范围内的近红外透射光谱。首先,采用光谱-理化值共生距离(SPXY)算法将调和油样品划分为38个校正集和13个预测集样品。其次,考察了主成分回归(PCR)、偏最小二乘(PLS)、支持向量回归(SVR)、人工神经网络(ANN)、极限学习机(ELM)等五种多元校正方法对五元调和油各组分定量分析的建模效果。然后,在最佳建模方法的基础上比较了SG平滑、标准正态变量(SNV)、多元散射校正(MSC)、一阶导数(1st Der)、二阶导数(2nd Der)和连续小波变换(CWT)六种光谱预处理方法,并讨论了预处理方法有效地原因。最后,在最佳预处理方法的基础上进一步利用竞争自适应重加权采样(CARS)和蒙特卡罗无信息变量消除法(MCUVE)筛选与预测组分相关的变量。结果显示,在五种建模方法中,PLS是最佳的建模方法,对玉米油、大豆油、稻米油、葵花油和芝麻油五种组分的预测均方根误差(RMSEP)分别为5.564 4,5.559 2,3.592 6,7.421 8和4.193 0。经过光谱预处理-变量选择,再建立PLS模型,对五种组分的RMSEP分别降低至1.955 3,0.562 4,1.145 0,1.619 0和1.067 1,预测相关系数(Rp)均高于0.98,表明采用合适的光谱预处理和变量选择方法,可以明显提高五元调和油中各单组分油定量分析的预测准确度。该研究为多组分调和油的快速无损定量检测提供了一种参考。 相似文献
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小分子添加剂在气体分离膜中的应用进展 总被引:2,自引:0,他引:2
综述了小分子添加剂在气体分离膜研究中的应用进展,重点介绍了钴金属络合物和小分子液晶对提高膜渗透选择性能的特殊作用。 相似文献
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在乙醇/水体系中采用KBH4液相还原法, 以石墨微粉为载体, Cu为复合金属, 通过两步法合成了具有球状团簇结构的负载型纳米Cu/Fe二元合金. 与单纯负载型纳米Fe0相比, 该复合材料对三氯乙烯(TCE)具有更高的还原脱氯性能, 纳米Fe0的质量浓度为10 g/L时, 5 h内能将10 mg/L的TCE完全去除. 将十六烷基三甲基溴化铵(CTAB)用于负载型纳米二元合金的表面改性, 改性后的材料对TCE的还原脱氯性能提高. 改性材料连续降解TCE 36 d, 10.2 mg/L TCE在7 h内即完全去除, 材料改性后不易氧化失活, 还原性能保持长期稳定. 相似文献
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无论是应对高考,还是各种应用技术技能的创新,物理知识都起着基础性、关键性的作用.但是,在实际的教师教学中,总有些内容学生难以完全理解,更难以推进下一步的学习.然而,教学实践中那些喜欢反思的学生,即使课堂学习存在着各种疑惑,却总能通过自我反思学习得以化解,由此开展反思教学的高中物理教学实践. 相似文献
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How the microscopic structure of complex network takes influence on the epidemic propagation is investigated. Special attention is paid to the growing network where its average degree changes with time. A formula for the final density of infected individuals is given and is confirmed by numerical simulations. Our results show that the final density of refractory increases nonlinearly with both the average degree of nodes and the adjustable random parameter of network structure. 相似文献