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利用扣除系数法估算线状地物面积 被引量:2
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作者 郭丽娇 殷耀国 马旭 《测绘通报》 CSCD 北大核心 2012年第S1期771-772,共2页
为了确定土地分类面积,需在地类图斑中扣除线状地物面积。在第二次全国土地调查中,利用卫星遥感正射影像(DOM)解译线状地物长度D,实地逐一量取宽度K,计算其面积。宁夏灌区基本农田建设标准高,沟渠路纵横密布,逐一量取宽度,需要较多技术... 为了确定土地分类面积,需在地类图斑中扣除线状地物面积。在第二次全国土地调查中,利用卫星遥感正射影像(DOM)解译线状地物长度D,实地逐一量取宽度K,计算其面积。宁夏灌区基本农田建设标准高,沟渠路纵横密布,逐一量取宽度,需要较多技术人员和定位设备(如便携GPS),还需及时检核。否则会出现宽度错位,严重时要大量返工。为了保证质量和提高工作效率,本文提出利用扣除系数法估算线状地物面积:在调查区域内,划定一些分布均匀、大小适宜的工作样方,逐一实测样方内各类线状地物宽度,计算扣除系数,最终利用扣除系数法估计调查区域内的线状地物面积。并以中宁县"二调"成果为依据,对扣除系数法进行深入研究。结果表明,利用扣除系数法估算线状地物面积,在地形情况如同试验区域的情况下可以用来计算耕地面积,利用这种方法可以大大减少工作量,提高工作效率,为测量的外业工作提供了方便。 展开更多
关键词 土地调查 线状地物面积 扣除系数法 工作样方 估算
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Using the contact network model and Metropolis-Hastings sampling to reconstruct the COVID-19 spread on the “Diamond Princess” 被引量:10
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作者 Feng Liu Xin Li Gaofeng Zhu 《Science Bulletin》 SCIE EI CAS CSCD 2020年第15期1297-1305,M0004,共10页
Traditional compartmental models such as SIR(susceptible,infected,recovered)assume that the epidemic transmits in a homogeneous population,but the real contact patterns in epidemics are heterogeneous.Employing a more ... Traditional compartmental models such as SIR(susceptible,infected,recovered)assume that the epidemic transmits in a homogeneous population,but the real contact patterns in epidemics are heterogeneous.Employing a more realistic model that considers heterogeneous contact is consequently necessary.Here,we use a contact network to reconstruct unprotected,protected contact,and airborne spread to simulate the two-stages outbreak of COVID-19(coronavirus disease 2019)on the‘‘Diamond Princess"cruise ship.We employ Bayesian inference and Metropolis-Hastings sampling to estimate the model parameters and quantify the uncertainties by the ensemble simulation technique.During the early epidemic with intensive social contacts,the results reveal that the average transmissibility t was 0.026 and the basic reproductive number R0 was 6.94,triple that in the WHO report,indicating that all people would be infected in one month.The t and R0 decreased to 0.0007 and 0.2 when quarantine was implemented.The reconstruction suggests that diluting the airborne virus concentration in closed settings is useful in addition to isolation,and high-risk susceptible should follow rigorous prevention measures in case exposed.This study can provide useful implications for control and prevention measures for the other cruise ships and closed settings. 展开更多
关键词 Contact network model SMALL-WORLD Chain-binomial model Airborne spread TRANSMISSIBILITY The basic reproductive number R0
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