期刊文献+
共找到3篇文章
< 1 >
每页显示 20 50 100
The effect of control measures on COVID-19 transmission in Italy:Comparison with Guangdong province in China 被引量:3
1
作者 Pei-Yu Liu Sha He +1 位作者 Li-Bin Rong San-Yi Tang 《Infectious Diseases of Poverty》 SCIE 2020年第5期116-116,共1页
Background:COVID-19 has spread all around the world.Italy is one of the worst affected countries in Europe.Although there is a trend of relief,the epidemic situation hasn’t stabilized yet.This study aims to investiga... Background:COVID-19 has spread all around the world.Italy is one of the worst affected countries in Europe.Although there is a trend of relief,the epidemic situation hasn’t stabilized yet.This study aims to investigate the dynamics of the disease spread in Italy and provide some suggestions on containing the epidemic.Methods:We compared Italy’s status at the outbreak stage and control measures with Guangdong Province in China by data observation and analysis.A modified autonomous SEIR model was used to study the COVID-19 epidemic and transmission potential during the early stage of the outbreak in Italy.We also utilized a time-dependent dynamic model to study the future disease dynamics in Italy.The impact of various non-pharmaceutical control measures on epidemic was investigated through uncertainty and sensitivity analyses.Results:The comparison of specific measures implemented in the two places and the time when the measures were initiated shows that the initial prevention and control actions in Italy were not sufficiently timely and effective.We estimated parameter values based on available cumulative data and calculated the basic reproduction number to be 4.32 before the national lockdown in Italy.Based on the estimated parameter values,we performed numerical simulations to predict the epidemic trend and evaluate the impact of contact limitation,detection and diagnosis,and individual behavior change due to media coverage on the epidemic.Conclusions:Italy was in a severe epidemic status and the control measures were not sufficiently timely and effective in the beginning.Non-pharmaceutical interventions,including contact restrictions and improvement of case recognition,play an important role in containing the COVID-19 epidemic.The effect of individual behavior changes due to media update of the outbreak cannot be ignored.For policy-makers,early and strict blockade measures,fast detection and improving media publicity are key to containing the epidemic. 展开更多
关键词 COVID-19 cumulative cases control measures Model prediction
原文传递
控释尿素养分速测及在田间土壤中氮素释放率研究 被引量:12
2
作者 颜晓 张民 +3 位作者 魏宗强 刘之广 张庆富 宗晓庆 《水土保持学报》 CSCD 北大核心 2010年第1期167-171,共5页
介绍了一种树脂包膜尿素工厂在线质检的养分速测方法,即,100℃快速浸提对二甲氨基苯甲醛分光光度法,建立了该方法与缓释肥料国家标准(GB/T23348-2009)中规定的25℃静水浸提凯氏定氮法测定结果之间的相关关系,验证了该速测方法预测计算... 介绍了一种树脂包膜尿素工厂在线质检的养分速测方法,即,100℃快速浸提对二甲氨基苯甲醛分光光度法,建立了该方法与缓释肥料国家标准(GB/T23348-2009)中规定的25℃静水浸提凯氏定氮法测定结果之间的相关关系,验证了该速测方法预测计算肥料养分释放期的可行性;将控释尿素施用于田间土壤,实时监测土壤的温湿度状况,对比了控释尿素在25℃水与田间土壤中的氮素累积释放趋势。结果表明:(1)100℃浸提对二甲氨基苯甲醛分光光度法可以准确的预测树脂包膜尿素在25℃下的养分释放率和养分释放期。应用此法测定预测样品S1和S2的养分释放期的误差分别只有0.10d和1.75d,相对误差不超过2.3%。(2)控释尿素S1、S3分别在25℃水中与田间耕层土壤(75%相对含水量)中的氮素释放趋势基本一致。25℃静水与耕层土壤的温差(<5℃)较小,不足以引起肥料在两介质中氮素累积释放率的显著差异。 展开更多
关键词 控释尿素 氮素累积释放率 快速浸提测定法 对二甲氨基苯甲醛分光光度法 凯氏定氮法 土壤
下载PDF
基于时空控制指标的联合作战能力分析 被引量:2
3
作者 罗睿 常歌 王强 《指挥控制与仿真》 2019年第6期12-17,共6页
作战力量的运用除带来政治经济影响和物资人员消耗等方面的效用外,同样还提供和保证了在特定时间条件下对特定空间的控制力,基于这种认识提出等效时空控制概念,及相应的单元模型分析、复杂系统聚合分析方法,其实质是通过特定时间里机动... 作战力量的运用除带来政治经济影响和物资人员消耗等方面的效用外,同样还提供和保证了在特定时间条件下对特定空间的控制力,基于这种认识提出等效时空控制概念,及相应的单元模型分析、复杂系统聚合分析方法,其实质是通过特定时间里机动、预警、火力等因素对空间控制的综合累积效应来评价联合作战能力大小。相对从火力、机动、预警等不同方面分别进行的作战能力定性定量分析,或者基于指数的作战能力分析,通过理论分析和数字计算表明,这种方法既有较好的综合性,也有更好的解析性质和可理解性,并能直观地实现单装能力向体系能力的聚合。 展开更多
关键词 联合作战能力 累积时空控制指标 二项分布 覆盖因子 指数聚合
下载PDF
上一页 1 下一页 到第
使用帮助 返回顶部