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Speed selection of traveling waves to an epidemic model

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International Journal of Biomathematics 2023年第4期16卷 155-173页

作者： yahui wang Xinjian wang Guo Lin School of Mathematics and Statistics Lanzhou University LanzhouGansu 730000P.R.China

This paper is devoted to investigating the selection mechanism of the minimal wave speed for traveling waves to an epidemic *** determinacy of linear and nonlinear selections is further discussed by the upper-lower solutions and comparison principle.A threshold is defined by the eigenvalue problem of the linearized *** show that the nonlinear determinacy is obtained as long as there exists a lower solution with a faster decay and a speed parameter that is larger than the *** the speed parameter equals to the threshold,if there exists an upper solution satisfying proper limit behavior,then the linear selection is *** a special function of infection rate,we obtain a threshold parameter that determines the linear and nonlinear selections.

关键词： Cooperative system minimal wave speed linear determinacy nonlinear selection comparison principle

融合负荷引力聚类与深度Q网络的智能化台区设计

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电工电能新技术 2024年第8期43卷 105-112页

作者：奚振乾韩祝明王亚辉任新丁崔秋实国网安徽省电力有限公司安徽合肥230022 安徽明生恒卓科技有限公司安徽合肥230031 上海电力大学电气工程学院上海200090 郑州大方软件股份有限公司河南郑州450052 重庆大学电气工程学院重庆400044

随着电网的深化改革,对电网企业的精准投资和合理运行也提出了更高的要求。传统的配电台区规划设计,缺少科学的计算模型,导致设计阶段即出现供电距离长、导线曲折系数大等一系列问题。为了更好地推进配电台区规划设计方案科学制定,本文... 详细信息

随着电网的深化改革,对电网企业的精准投资和合理运行也提出了更高的要求。传统的配电台区规划设计,缺少科学的计算模型,导致设计阶段即出现供电距离长、导线曲折系数大等一系列问题。为了更好地推进配电台区规划设计方案科学制定,本文提出了一种基于强化学习的台区智能一体化规划设计方法。本文首先利用用户的历史负荷数据,采用负荷间引力的密度聚类算法对用户区域进行合理地划分,确定负荷中心。在划分好的区域内,采用深度强化学习算法对用户点、负荷中心点以及障碍物进行建模,设定最优路线的损失函数,对乡镇台区低压线路拓扑结构进行合理的规划设计。最后基于规划设计的拓扑及用户历史用电数据开展节点中性线电流最小计算,给出单相用户到相计算,实现低压电网中性线损耗最低。本文利用安徽省某地区的实际情况进行验证,使用本文所提的方法改造低压台区,变压器的布局偏移负荷中心点仅17 m,台区的线损率为1.5%,低于2.0%。

关键词：台区智能规划设计负荷引力密度聚类深度强化学习

茶树NAC转录因子基因CsNAC79和CsNAC9鉴定及其对非生物胁迫的响应

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西北植物学报 2024年第4期44卷 572-581页

作者：孔洁玙杨妮罗微胡志航王雅慧庄静南京农业大学园艺学院茶叶科学研究所农业农村部华东地区园艺作物生物学与种质创制重点实验室南京210095 南京农业大学作物遗传与种质创新利用全国重点实验室南京210095

【目的】鉴定茶树NAC转录因子基因CsNAC79和CsNAC9,并分析它们在干旱、盐、高温、低温、外施ABA和外施GA3胁迫下的表达模式,为进一步解析CsNAC79和CsNAC9转录因子的生物学功能提供参考。【方法】以茶树‘龙井43’为材料,用RT-PCR扩增NA... 详细信息

【目的】鉴定茶树NAC转录因子基因CsNAC79和CsNAC9,并分析它们在干旱、盐、高温、低温、外施ABA和外施GA3胁迫下的表达模式,为进一步解析CsNAC79和CsNAC9转录因子的生物学功能提供参考。【方法】以茶树‘龙井43’为材料,用RT-PCR扩增NAC转录因子家族基因CsNAC79和CsNAC9,并进行生物信息学分析;用qRT-PCR检测CsNAC79和CsNAC9在茶树6种非生物胁迫下的相对表达量。【结果】(1)CsNAC79和CsNAC9分别编码409个和282个氨基酸,且分别在15—150氨基酸位点、11—134氨基酸位点含有NAC家族成员典型的NAM保守结构域。(2)CsNAC79蛋白与中华猕猴桃、柿、洋蓟亲缘关系较近,CsNAC9蛋白与桃、荔枝、榴莲亲缘关系较近;2个NAC转录因子均是亲水性蛋白,皆不含信号肽和跨膜结构;CsNAC79和CsNAC9的启动子区域都含有非生物胁迫响应元件;蛋白质空间结构分析显示,CsNAC79和CsNAC9蛋白主要是由不规则卷曲和α-螺旋组成。(3)表达分析表明:CsNAC79和CsNAC9基因在6种不同非生物胁迫下均上调表达。【结论】茶树CsNAC79和CsNAC9基因响应多种非生物胁迫。

关键词：茶树 NAC转录因子 ABA GA_(3) 非生物胁迫表达分析

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锂离子电池不可逆膨胀模型及应用

电子科技 2024年第9期37卷 8-13页

作者：汪亚辉李培超王克用上海工程技术大学机械与汽车工程学院上海201600

针对锂离子电池多次充放电循环后容量衰减量的快速估算问题,文中基于锂离子电池(Lithium-Ion Battery,LIB)容量衰减模型提出了一种利用电池外部膨胀位移快速估算其内部容量衰减的方法。在锂离子电池容量衰减模型的基础上推导其径向不可... 详细信息

针对锂离子电池多次充放电循环后容量衰减量的快速估算问题,文中基于锂离子电池(Lithium-Ion Battery,LIB)容量衰减模型提出了一种利用电池外部膨胀位移快速估算其内部容量衰减的方法。在锂离子电池容量衰减模型的基础上推导其径向不可逆膨胀模型,通过COMSOL Multiphysics对圆柱形锂离子电池Sanyo UR18650E进行建模和求解,并对比数值结果与实验数据,从而对所提模型进行验证。基于上述模型,分析了电池在充放电循环过程中由于副反应参与而造成的容量衰减和不可逆膨胀行为的原因。结果表明,副反应速率变化造成了副反应产物浓度在负极的梯度分布,副反应产物堆积使电池膨胀位移随循环线性增长。文中还利用副反应产物作为桥梁得到电池容量衰减与其径向位移的函数计算式,为容量衰减量的快速估算提供了新方法。

关键词：锂离子电池容量衰减膨胀 SEI 电化学-热-力电池管理系统副反应电池老化

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直流等离子体球化钨粉制备及其性能研究

中国材料进展 2024年第8期43卷 753-759页

作者：张卫刚孙杨郑敏高岭刘璐汪舸王娅辉杨肖肖西安优耐特容器制造有限公司陕西西安710201

直流电弧等离子体具有核心温度高、环境清洁等特点,且制备出的粉体球形度高、球化率高,成为增材制造用高质量粉体规模化生产的重要技术。以不规则钨粉为原料,采用直流电弧等离子体球化技术制备球形钨粉,研究不同送粉速率及送粉气流量对... 详细信息

直流电弧等离子体具有核心温度高、环境清洁等特点,且制备出的粉体球形度高、球化率高,成为增材制造用高质量粉体规模化生产的重要技术。以不规则钨粉为原料,采用直流电弧等离子体球化技术制备球形钨粉,研究不同送粉速率及送粉气流量对球化后粉末颗粒性能的影响,证明不规则钨粉球化过程中的3种转变机制,并在较大送粉气流量下,采用直流电弧等离子体球化技术原位合成了纳米颗粒附着的球形钨粉。采用扫描电子显微镜、X射线衍射仪、激光粒度仪、粉末流动性测试仪对球化后钨粉颗粒的形貌、物相、粒径分布、流动性及松装密度等进行分析表征。结果表明:经直流电弧等离子体球化后钨粉颗粒物相未发生变化,呈现出单一钨相,送粉速率为8 r·min^(-1)时,制备的钨粉颗粒表面光滑且球化率可达到98%以上,粒径分布相较于原料粉末变窄。球化后钨粉的流动性最高,达到5.35 s·50 g^(-1),相较原料钨粉减少了13.18 s;松装密度由5.37提高到11.67 g·cm^(-3),提高了117.3%。

关键词：直流电弧等离子体钨粉球化率送粉气流量球化机制

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Attribution analysis for water yield service based on the geographical detector method:A case study of the Hengduan Mountain region

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Journal of Geographical Sciences 2020年第6期30卷 1005-1020页

作者： DAI Erfu wang yahui Lhasa Plateau Ecosystem Research Station Key Laboratory of Ecosystem Network Observation and Mod-elingInstitute of Geographic Sciences and Natural Resources ResearchCASBeijing 100101China University of Chinese Academy of Sciences Beijing 100049China

Ecosystem services,which include water yield services,have been incorporated into decision processes of regional land use planning and sustainable *** pattern characteristics and identification of factors that influence water yield are the basis for decision ***,there are limited studies on the driving mechanisms that affect the spatial heterogeneity of ecosystem *** this study,we used the Hengduan Mountain region in southwest China,with obvious spatial heterogeneity,as the research *** water yield module in the InVEST software was used to simulate the spatial distribution of water ***,quantitative attribution analysis was conducted for various geomorphological and climatic zones in the Hengduan Mountain region by using the geographical detector *** factors,such as climate,topography,soil,vegetation type,and land use type and pattern,were taken into consideration for this *** key findings were ***,water yield spatial heterogeneity is influenced most by climate-related factors,where precipitation and evapotranspiration are the dominant ***,the relative importance of each impact factor to the water yield heterogeneity differs significantly by geomorphological and climatic *** flat areas,the influence of evapotranspiration is higher than that of *** relief increases,the importance of precipitation increases and eventually,it becomes the most influential *** is the most influential factor in a plateau climate zone,while in the mid-subtropical zone,precipitation is the main controlling ***,land use type is also an important driving force in flat ***,more attention should be paid to urbanization and land use planning,which involves land use changes,to mitigate the impact on water yield spatial *** fourth finding was that a risk detector showed that Primarosol and Anthropogenic soil areas,shrub areas,and areas with sl

关键词： water yield service Hengduan Mountain region InVEST software geographical detector attribution analysis

Photosynthesis adaption in Korean pine to gap size and position within Populus davidiana forests in Xiaoxing’anling, China

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Journal of Forestry Research 2022年第5期33卷 1517-1527页

作者： Xuannan Li yahui wang Zhihui Yang Ting Liu Changcheng Mu Center for Ecological Research Northeast Forestry UniversityHarbinHeilongjiang 150040People’s Republic of China

Forest gaps restrict the restoration of temperate secondary forest to broad-leaved Korean pine forest in zonal climax vegetation by affecting the growth of Korean pine(Pinus koraiensis).However,the photo synthetic adaptability of Korean pine to gap size and position within the gap is *** order to explore the adaptability of young Korean pine(35 years) to different gap sizes in Xiaoxing’anling,photo synthetic capacity and microenvironmental factors(leaf temperature,light transmittance) of Korean pine needles in three positions in the gap(central,transition,and edge areas) were *** gaps were identified in the secondary Populus davidiana forest:a large 201 m^(2) gap,a middle 112 m^(2) gap,and a small 50 m^(2) gap;12 m^(2) of the understory was sampled as a *** results show that:(1) maximum net photosynthetic rate(P_(max)) in needles of Korean pine growing in the large gap was higher than in the small gap,and P_(max) in the centre in the same gap was higher than in the transition and edge areas;(2) light saturation point(LSP) and photosynthetic quantum yield(AQY)of needles in the large gap were higher than in the small gap,while the light compensation point(LCP) and chlorophyll contents of needles were lower in the small gap;and,(3)P_(max) had a significant positive correlation with temperature and light *** is suggested that the larger the gap in secondary Populus davidiana forests,the greater the change in light intensity and temperatures,the stronger the light adaption of Korean pine needles and the higher the photosynthetic ***,in the recovery of broadleaved/Korean pine forests,suitable gaps should be created and gap microhabitats fully utilized to accelerate the restoration process.

关键词： Pinus koraiensis Gap size Position in the gap Maximum net photosynthetic rate

Combining ectomycorrhizal fungi and plant growth-promoting rhizobacteria to enhance salt tolerance of Metasequoia glyptostroboides

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林业研究:英文版 2023年第5期34卷 1603-1614页

作者： Weiliang Kong Xiuqian Xu Zhenqian Li yahui wang Xiaoqin Wu Co-Innovation Centre for Sustainable Forestry in Southern China College of ForestryNanjing Forestry UniversityNanjing 210037People’s Republic of China Jiangsu Key Laboratory for Prevention and Management of Invasive Species Nanjing Forestry UniversityNanjing 210037People’s Republic of China

Plant growth and productivity are negatively affected by soil *** study investigated the effects of the rhizosphere-promoting bacterium,Bacillus paramycoides JYZ-SD5,and the ectomycorrhizal fungus,Schizophyllum commune Be,on the growth of Metasequoia glyptostroboides under salt *** in biomass,root growth,root ion distribution and in vivo enzyme activities were determined under different treatments(Be,JYZ-SD5,and Be+JYZ-SD5).The results show that all inoculations increased chlorophyll content,shoot length and root diameter with or without salt stress,and the effect of Be+JYZ-SD5was the ***-SD5 and Be+JYZ-SD5 treatments significantly increased root length,surface area,bifurcation number,tip number,main root length and diameter under salt *** chloroplast structures developed under both single and double *** to the control,root activities of *** in the Be,JYZSD5,and Be+JYZ-SD5 treatments increased by 31.3%,17.2%,and 33.7%.All treatments increased the activities of superoxide dismutase(SOD),peroxidase(POD),Na^(+)-K^(+)-ATPase and Ca^(2+)-Mg^(2+)-*** strongest effect was by Be+*** of root ion distribution showed that,under salt stress,Na^(+)and K^(+)decreased and were concentrated in the epidermis or ***/K ratios also *** Be+JYZ-SD5 treatment increased betaine by 130.3%and 97.9%under 50 mM and 100 mM salt stress,***,these changes result in the activation of physiological and biochemical processes involved in the mitigation of salinity-induced stress in ***.

关键词： Bacillus paramycoides Schizophyllum commune Metasequoia glyptostroboides Salt stress Plant growth

Remote sensing monitoring of the recent rapid increase in cultivation activities and its effects on desertification in the Mu Us Desert, China

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Journal of Arid Land 2023年第7期15卷 812-826页

作者： ZHAO Hongyan YAN Changzhen LI Sen wang yahui Key Laboratory of Desert and Desertification Northwest Institute of Eco-Environment and ResourcesChinese Academy of SciencesLanzhou 730000China University of Chinese Academy of Sciences Beijing 100049China National Earth System Science Data Center Beijing 100020China

The recent ecological improvement in the Mu Us Desert of China, largely attributed to large-scale afforestation projects, has created new opportunities for cultivation activities. However, the subsequent rapid increase in reclamation on desertification land and its impact on desertification have raised concerns. In this study, we first extracted data on cultivated land and desertification land in 1975,1990, 2000, 2005, 2010, 2015, and 2020 through the human-computer interaction visual interpretation method. By overlaying the cultivated land dynamics and desertification land, we subsequently explored the effect of cultivation activities on desertification in the Mu Us Desert during the six periods from 1975 to 2020(1975–1990, 1990–2000, 2000–2005, 2005–2010, 2010–2015, and 2015–2020). The results showed that cultivated land in the Mu Us Desert showed a fluctuating and increasing trend from 3769.26 km~2 in 1975 to 4865.73 km~2 in 2020, with 2010 as the turning point for the recent rapid increase. The main contributors included the large and regular patches distributed in Yuyang District and Shenmu of Shaanxi Province, and relatively smaller patches concentrated in Inner Mongolia Autonomous Region. The increased cultivated land from the reclamation on desertification land was dominated by moderate and severe desertification lands, and the decreased cultivated land that was transferred into desertification land as abandoned cultivated land was dominated by slight and moderate desertification lands. The effect of cultivation activities on desertification reversal(average area proportion of 10.61% for reversed desertification land) was greater than that of the development of desertification(average area proportion of 5.82% for developed desertification land). Nevertheless, compared to reversed desertification land,both the significant increase of developed desertification land during the periods of 2000–2005 and 2005–2010 and the insignificant decrease during the periods

关键词： cultivation activities desertification land desertification reversal and development reclamation spatial overlay analysis Mu Us Desert