【目的】筛查北京地区枣园感染枣疯病植原体的叶蝉种类,确定枣疯病植原体潜在介体昆虫,为预防和控制枣疯病流行提供科学依据。【方法】通过扫网法和黄板诱集法,对昌平区流村镇流村、海淀区西北旺镇唐家岭村、朝阳区奥林匹克森林公园、...【目的】筛查北京地区枣园感染枣疯病植原体的叶蝉种类,确定枣疯病植原体潜在介体昆虫,为预防和控制枣疯病流行提供科学依据。【方法】通过扫网法和黄板诱集法,对昌平区流村镇流村、海淀区西北旺镇唐家岭村、朝阳区奥林匹克森林公园、通州区永于路北京观光南瓜园4个地点枣树上叶蝉种类及枣疯病植原体感染的叶蝉进行调查和分子检测分析。【结果】北京地区枣园枣树上有13种叶蝉发生,其中包括片突菱纹叶蝉( Hishimonus lamellatus Cai et Kuoh)、凹缘菱纹叶蝉( H. sellatus (Uhler))、小绿叶蝉( Empoasca spp.)、斑叶蝉( Erythroneura sp.)、横带叶蝉( Scaphoideus festivus Matsumura)、大青叶蝉( Cicadella viridis (Linnaeus))、新县长突叶蝉( Batracomorphus xinxianensis Cai et Shen)、红闪小叶蝉( Zygina sp.)、白边大叶蝉( Kolla paulula (Walker))、桃一点叶蝉( Singapora shinshana (Matsumura))、一点木叶蝉( Phlogotettix cyclops (Mulsant et Rey))、条沙叶蝉( Psammotettix striatus (Linnaeus))和窗耳叶蝉( Ledra auditura Walker)。通过对采集的叶蝉标本采用植原体通用引物进行PCR检测,片突菱纹叶蝉( H. lamellatus )、凹缘菱纹叶蝉( H. sellatus )、大青叶蝉( C. viridis )、白边大叶蝉( K. paulula ),均发现感染枣疯病植原体,感染率分别为1.4%、3.0%、7.4%、8.3%,其他叶蝉经检测未发现感染植原体。【结论】凹缘菱纹叶蝉( H. sellatus )、片突菱纹叶蝉( H. lamellatus )、大青叶蝉( C. viridis )、白边大叶蝉( K. paulula )可能为潜在的枣疯病植原体介体昆虫。展开更多
A basic solution in series form for the three-phase composite cylindrical model in antiplane piezoelectricity subjected to the action of a singularity in the intermediate matrix region is presented. The solution is ob...A basic solution in series form for the three-phase composite cylindrical model in antiplane piezoelectricity subjected to the action of a singularity in the intermediate matrix region is presented. The solution is obtained through the complex potential approach in conjunction with the techniques of analytical continuation, singularity analysis, Laurent series expansion in an annular region and Cauchy integral formulae, etc. Based on the complex potentials obtained, explicit expressions for the distribution of stress and electric displacement in the three regions are also derived.展开更多
势支撑向量机P-SVM(potential support vector machine)作为一种新颖的封装型特征选择方法在许多领域得到了成功的运用,然而依据Fisher准则的基本原理发现势支撑向量机方法对应的目标函数只是类内离散度各类均值为0的一种特殊形式,从而...势支撑向量机P-SVM(potential support vector machine)作为一种新颖的封装型特征选择方法在许多领域得到了成功的运用,然而依据Fisher准则的基本原理发现势支撑向量机方法对应的目标函数只是类内离散度各类均值为0的一种特殊形式,从而使该方法的运用受到一定的限制.同时由于要求各类样本均值为0,一定程度上会导致在0矢量周围出现样本交叉,从而不利于P-SVM方法得到最优决策超平面,降低分类效果.因此利用一般的类内散度重新构造目标函数,提出一种广义的势支撑特征选择方法GPSFM(generalized potential support features selection method).GPSFM方法在一定程度上继承了P-SVM的优点,而且还具有特征选择冗余度低、选择速度快和适应能力强的特点,从而使得该方法表现出较之于P-SVM更好的特征选择和分类效果.实验结果表明该方法具有上述优势.展开更多
In this paper, we modify the convective vorticity vector (CVV) defined as a cross product of absolute vorticity and gradient of equivalent potential temperature to moist potential vorticity vector (MPVV) defined as a ...In this paper, we modify the convective vorticity vector (CVV) defined as a cross product of absolute vorticity and gradient of equivalent potential temperature to moist potential vorticity vector (MPVV) defined as a cross product of absolute vorticity () and the gradient of the moist-air entropy potential temperature (). The patterns of (MPVV) are compared with the patterns of heavy rainfall events that occurred over different regions in Tanzania on 20<sup>th</sup> to 22<sup>nd</sup> December, 2011 and on 5<sup>th</sup> to 8<sup>th</sup> May, 2015. Moreover, the article aimed at assessing the relative contributions of the magnitude, horizontal and vertical components of (MPVV) detecting on the observed patterns of rainfall events. Dynamic and thermodynamic variables: wind speed, temperature, atmospheric pressure and relative humidity from numerical output generated by the Weather Research and Forecasting (WRF) model running at Tanzania Meteorological Agency (TMA) were used to compute MPVV. It is found that MPVV provide accurate tracking of locations received heavy rainfall, suggesting its potential use as a dynamic tracer for heavy rainfall events in Tanzania. Finally it is found that the first and second components of MPVV contribute almost equally in tracing locations received heavy rainfall events. The magnitude of MPVV described the locations received heavy rainfall events better than the components.展开更多
文摘【目的】筛查北京地区枣园感染枣疯病植原体的叶蝉种类,确定枣疯病植原体潜在介体昆虫,为预防和控制枣疯病流行提供科学依据。【方法】通过扫网法和黄板诱集法,对昌平区流村镇流村、海淀区西北旺镇唐家岭村、朝阳区奥林匹克森林公园、通州区永于路北京观光南瓜园4个地点枣树上叶蝉种类及枣疯病植原体感染的叶蝉进行调查和分子检测分析。【结果】北京地区枣园枣树上有13种叶蝉发生,其中包括片突菱纹叶蝉( Hishimonus lamellatus Cai et Kuoh)、凹缘菱纹叶蝉( H. sellatus (Uhler))、小绿叶蝉( Empoasca spp.)、斑叶蝉( Erythroneura sp.)、横带叶蝉( Scaphoideus festivus Matsumura)、大青叶蝉( Cicadella viridis (Linnaeus))、新县长突叶蝉( Batracomorphus xinxianensis Cai et Shen)、红闪小叶蝉( Zygina sp.)、白边大叶蝉( Kolla paulula (Walker))、桃一点叶蝉( Singapora shinshana (Matsumura))、一点木叶蝉( Phlogotettix cyclops (Mulsant et Rey))、条沙叶蝉( Psammotettix striatus (Linnaeus))和窗耳叶蝉( Ledra auditura Walker)。通过对采集的叶蝉标本采用植原体通用引物进行PCR检测,片突菱纹叶蝉( H. lamellatus )、凹缘菱纹叶蝉( H. sellatus )、大青叶蝉( C. viridis )、白边大叶蝉( K. paulula ),均发现感染枣疯病植原体,感染率分别为1.4%、3.0%、7.4%、8.3%,其他叶蝉经检测未发现感染植原体。【结论】凹缘菱纹叶蝉( H. sellatus )、片突菱纹叶蝉( H. lamellatus )、大青叶蝉( C. viridis )、白边大叶蝉( K. paulula )可能为潜在的枣疯病植原体介体昆虫。
文摘A basic solution in series form for the three-phase composite cylindrical model in antiplane piezoelectricity subjected to the action of a singularity in the intermediate matrix region is presented. The solution is obtained through the complex potential approach in conjunction with the techniques of analytical continuation, singularity analysis, Laurent series expansion in an annular region and Cauchy integral formulae, etc. Based on the complex potentials obtained, explicit expressions for the distribution of stress and electric displacement in the three regions are also derived.
文摘势支撑向量机P-SVM(potential support vector machine)作为一种新颖的封装型特征选择方法在许多领域得到了成功的运用,然而依据Fisher准则的基本原理发现势支撑向量机方法对应的目标函数只是类内离散度各类均值为0的一种特殊形式,从而使该方法的运用受到一定的限制.同时由于要求各类样本均值为0,一定程度上会导致在0矢量周围出现样本交叉,从而不利于P-SVM方法得到最优决策超平面,降低分类效果.因此利用一般的类内散度重新构造目标函数,提出一种广义的势支撑特征选择方法GPSFM(generalized potential support features selection method).GPSFM方法在一定程度上继承了P-SVM的优点,而且还具有特征选择冗余度低、选择速度快和适应能力强的特点,从而使得该方法表现出较之于P-SVM更好的特征选择和分类效果.实验结果表明该方法具有上述优势.
基金supported by the National Natural Science Foundation of China (70602017)National social Science Foundation of China (07BJY034)Social Science Foundation of China Ministry of Education (07JC630061)
文摘In this paper, we modify the convective vorticity vector (CVV) defined as a cross product of absolute vorticity and gradient of equivalent potential temperature to moist potential vorticity vector (MPVV) defined as a cross product of absolute vorticity () and the gradient of the moist-air entropy potential temperature (). The patterns of (MPVV) are compared with the patterns of heavy rainfall events that occurred over different regions in Tanzania on 20<sup>th</sup> to 22<sup>nd</sup> December, 2011 and on 5<sup>th</sup> to 8<sup>th</sup> May, 2015. Moreover, the article aimed at assessing the relative contributions of the magnitude, horizontal and vertical components of (MPVV) detecting on the observed patterns of rainfall events. Dynamic and thermodynamic variables: wind speed, temperature, atmospheric pressure and relative humidity from numerical output generated by the Weather Research and Forecasting (WRF) model running at Tanzania Meteorological Agency (TMA) were used to compute MPVV. It is found that MPVV provide accurate tracking of locations received heavy rainfall, suggesting its potential use as a dynamic tracer for heavy rainfall events in Tanzania. Finally it is found that the first and second components of MPVV contribute almost equally in tracing locations received heavy rainfall events. The magnitude of MPVV described the locations received heavy rainfall events better than the components.
