It is very important to locate and track weather systems which cause severe calamity,such as severeconvective clouds (SCC),in nowcasting. In this paper the recognition and tracking of SCC is studied withGMS IR images ...It is very important to locate and track weather systems which cause severe calamity,such as severeconvective clouds (SCC),in nowcasting. In this paper the recognition and tracking of SCC is studied withGMS IR images using computer image techniques. As an IR image preprocessing, a SCC futerlng algorithm is put forward that combines a segment smoothing filtering and a removal procedure by thresholds. To the filtered SCCs the T algorithm and IP algorithm of contour coding method are applied to extract the contour line and its initial point. The description of SCCs includes four characteristic quanti-ties, i. e. center of gravity, cloud size, moment invariant M and R-shaped descriptor. Pattern recosnitionand pattern matching techniques are used to track the SCCs. Two procedures of rough and fine matchingare given. The former procedure include the setting of searching area and recognition of area and the latter is composed by the matching of shape descriptor R and moment invariant M and the analysis of correlative brightness temperature analysis.展开更多
Based on the fast algorithm of meteorological satellite guide wind vector tracing, cloud motion wind vector is calculated. According to the different characteristics of cloud motion wind field and sounding wind field,...Based on the fast algorithm of meteorological satellite guide wind vector tracing, cloud motion wind vector is calculated. According to the different characteristics of cloud motion wind field and sounding wind field, a method which fuses conventional data with unconventional data based on variation principle is presented. The fundamental is constructing a cost function that makes the value approach conventional data and the gradient approach unconventional data. Using this method, the conventional wind and the cloud motion wind are fused. The fused wind field has high resolu- tion. Its wind direction approaches cloud motion wind which indicates move direction of the synoptic system, and its velocity approaches conventional wind which indicates move velocity of the synoptic system. The wind field data are used for short-time forecast of severe convective weather location, which gets a good result.展开更多
Virtual machines have attracted significant attention especially within the high performance computing community. How- ever, there remain problems with respect to security in general and intrusion detection and diagno...Virtual machines have attracted significant attention especially within the high performance computing community. How- ever, there remain problems with respect to security in general and intrusion detection and diagnosis in particular which underpin the realization of the potential offered by this emerging technology. In this paper, one such problem has been highlighted, i.e., intrusion severity analysis for large-scMe virtual machine based systems, such as clouds. Furthermore, the paper proposes a solution to this prob- lem for the first time for clouds. The proposed solution achieves virtual machine specific intrusion severity analysis while preserving isolation between the security module and the monitored virtual machine. Furthermore, an automated approach is adopted to signif- icantly reduce the overall intrusion response time. The paper includes a detailed description of the solution and an evaluation of our approach with the objective to determine the effectiveness and potential of this approach. The evaluation includes both architectural and experimentM evaluation thereby enabling us to strengthen our approach at an architectural level as well. Finally, open problems and challenges that need to be addressed in order to make further improvements to the proposed approach have been highlighted.展开更多
Cloud seeding is a method of artificially causing clouds to produce precipitation (降水) in the form of rain or snow.Cloud seeding has also been used in attempts to modify the severity of hail slorms and hurricanes.Th...Cloud seeding is a method of artificially causing clouds to produce precipitation (降水) in the form of rain or snow.Cloud seeding has also been used in attempts to modify the severity of hail slorms and hurricanes.The effectiveness of cloud seeding remains controversial,but it continues to be used in some regions to try lo展开更多
以3D—Barnes方案插值的兰州站新一代天气雷达反射率因子等高平面资料，用垂直累积液态含水量（Vertically Integrated Liquid Water Content，简称：VIL）的理论模式计算单体VIL、用MAX函数逐次提取最大VIL（简称：VILmax），采用统计...以3D—Barnes方案插值的兰州站新一代天气雷达反射率因子等高平面资料，用垂直累积液态含水量（Vertically Integrated Liquid Water Content，简称：VIL）的理论模式计算单体VIL、用MAX函数逐次提取最大VIL（简称：VILmax），采用统计和分段函数处理技术，对20042005年5～8月青藏高原东北侧的32个强对流云单体VILmax的演变特征及其在冰雹云识别中的应用进行了分析。结果表明：（1）强对流云单体VILmax在演变过程中均是先增加，后减少，在时间序列曲线中表现为单峰型特征，其中冰雹云单体VILmax存在“爆发式增长及突然降低”现象，这是区别雷雨云单体的一个重要特征；（2）冰雹云单体首次降雹前4个资料时间间隔内VILmax将出现两次“爆发式增长”现象，第一次爆发式增长时不会降雹，维持1～2个资料时间间隔后第二次出现时开始降雹；同一单体再次降雹前没有第一次“爆发式增长”现象，出现“突然降低”现象时降雹均停止；（3）VILmax变化率（简称：GVILmax）的“正（负）峰”现象与冰雹云单体VILmax的“爆发式增长及突然降低”现象对应的时间完全吻合，利用GVILmax建立的冰雹云识别流程在实际业务中具有较高的使用价值。展开更多
文摘It is very important to locate and track weather systems which cause severe calamity,such as severeconvective clouds (SCC),in nowcasting. In this paper the recognition and tracking of SCC is studied withGMS IR images using computer image techniques. As an IR image preprocessing, a SCC futerlng algorithm is put forward that combines a segment smoothing filtering and a removal procedure by thresholds. To the filtered SCCs the T algorithm and IP algorithm of contour coding method are applied to extract the contour line and its initial point. The description of SCCs includes four characteristic quanti-ties, i. e. center of gravity, cloud size, moment invariant M and R-shaped descriptor. Pattern recosnitionand pattern matching techniques are used to track the SCCs. Two procedures of rough and fine matchingare given. The former procedure include the setting of searching area and recognition of area and the latter is composed by the matching of shape descriptor R and moment invariant M and the analysis of correlative brightness temperature analysis.
文摘Based on the fast algorithm of meteorological satellite guide wind vector tracing, cloud motion wind vector is calculated. According to the different characteristics of cloud motion wind field and sounding wind field, a method which fuses conventional data with unconventional data based on variation principle is presented. The fundamental is constructing a cost function that makes the value approach conventional data and the gradient approach unconventional data. Using this method, the conventional wind and the cloud motion wind are fused. The fused wind field has high resolu- tion. Its wind direction approaches cloud motion wind which indicates move direction of the synoptic system, and its velocity approaches conventional wind which indicates move velocity of the synoptic system. The wind field data are used for short-time forecast of severe convective weather location, which gets a good result.
基金National Natural Science Foundation of China （NoA0905019, 40975023 ） The R ＆ D Special Foundation for Public Welfare Industry （Meteorol- ogy） （No. GYHY200906003）
文摘Virtual machines have attracted significant attention especially within the high performance computing community. How- ever, there remain problems with respect to security in general and intrusion detection and diagnosis in particular which underpin the realization of the potential offered by this emerging technology. In this paper, one such problem has been highlighted, i.e., intrusion severity analysis for large-scMe virtual machine based systems, such as clouds. Furthermore, the paper proposes a solution to this prob- lem for the first time for clouds. The proposed solution achieves virtual machine specific intrusion severity analysis while preserving isolation between the security module and the monitored virtual machine. Furthermore, an automated approach is adopted to signif- icantly reduce the overall intrusion response time. The paper includes a detailed description of the solution and an evaluation of our approach with the objective to determine the effectiveness and potential of this approach. The evaluation includes both architectural and experimentM evaluation thereby enabling us to strengthen our approach at an architectural level as well. Finally, open problems and challenges that need to be addressed in order to make further improvements to the proposed approach have been highlighted.
文摘Cloud seeding is a method of artificially causing clouds to produce precipitation (降水) in the form of rain or snow.Cloud seeding has also been used in attempts to modify the severity of hail slorms and hurricanes.The effectiveness of cloud seeding remains controversial,but it continues to be used in some regions to try lo
文摘以3D—Barnes方案插值的兰州站新一代天气雷达反射率因子等高平面资料，用垂直累积液态含水量（Vertically Integrated Liquid Water Content，简称：VIL）的理论模式计算单体VIL、用MAX函数逐次提取最大VIL（简称：VILmax），采用统计和分段函数处理技术，对20042005年5～8月青藏高原东北侧的32个强对流云单体VILmax的演变特征及其在冰雹云识别中的应用进行了分析。结果表明：（1）强对流云单体VILmax在演变过程中均是先增加，后减少，在时间序列曲线中表现为单峰型特征，其中冰雹云单体VILmax存在“爆发式增长及突然降低”现象，这是区别雷雨云单体的一个重要特征；（2）冰雹云单体首次降雹前4个资料时间间隔内VILmax将出现两次“爆发式增长”现象，第一次爆发式增长时不会降雹，维持1～2个资料时间间隔后第二次出现时开始降雹；同一单体再次降雹前没有第一次“爆发式增长”现象，出现“突然降低”现象时降雹均停止；（3）VILmax变化率（简称：GVILmax）的“正（负）峰”现象与冰雹云单体VILmax的“爆发式增长及突然降低”现象对应的时间完全吻合，利用GVILmax建立的冰雹云识别流程在实际业务中具有较高的使用价值。
