基于时间特征指数的水源地突发性污染事件应急评估方法研究

应急评估及其方法研究是建立水源地突发性污染事件应急机制的关键环节之一。在综合评价现有相关应急评估方法的基础上,根据水源地突发性污染事件的风险源不确定性、受体易损性以及需快速反应性等特征,提出了对突发性污染事件的危害影响程度进行应急评估的”时间特征指数”方法。选取了泄漏物质危害性、泄漏量、泄漏位置、流速和风速5项评估指标,计算得出能够反映突发性污染事件对取水口危害威胁性的综合指数。对上海市黄浦江上游水源地一起突发性污染事件进行了案例评估,结果表明该方法具有一定的科学性和可行性。

甘肃省手足口病时间风险特征的空间聚集性探测研究

目的探讨甘肃省手足口病的时空分布特征和发病风险区域,评估防控措施实施效果。方法收集2018年甘肃省87个县每周手足口病数据,分析手足口病的时间风险特征指数,采用空间聚类分析方法对时间风险特征指数的发病风险区进行可视化探测和分析。结果 2018年甘肃省手足口病共报告病例13571例,报告发病率为51.73/10万,全年有两个发病高峰。手足口病的时间风险特征指数(频率指数为0.430,持续时间指数为4.657,强度指数为11.106)存在空间聚集性,3个时间风险特征指数在定西市安定区和兰州市七里河区均呈现高值聚集状态,是手足口病发病的热点区域。结论甘肃省手足口病发病存在时空聚集性,安定区和七里河区是手足口病的发病高风险区域,不同发病风险区防控措施效果不同。

2016-2020年甘肃省流行性感冒时间风险特征时空分布

目的了解2016—2020年甘肃省流行性感冒(流感)的时空分布特征,评估防控措施实施效果。方法收集甘肃省87个县(区)每周流感数据进行空间扫描分析,采用空间自相关方法对流感的时间风险特征指数(频率指数、持续时间指数和强度指数)进行空间统计分析。结果共报告病例46043例,年均发病率35.09/10万。2016—2020年甘肃省流感高发病率的可能聚集区域集中在定西市和天水市。流感的频率指数为0.58,持续时间指数为5.73,强度指数为10.49。全局自相关显示,流感的频率指数和强度指数呈正向空间自相关,局部自相关显示,频率指数和强度指数的热点区域主要集中在定西市。结论甘肃省流感发病存在时空聚集性,定西市是流感的发病高风险区域,不同发病风险区防控措施效果不同。

The Time-Frequency Energy Attenuation Factor and Its Application on the Basis of Gauss Linear Frequency-Modulated Continuous Wavelet Transform

Based on the Gauss linear frequency modulated wavelet transform, a new characteristic index is presented, namely time frequency energy attenuation factor which can reflect the difference features of waveform in earthquake focus mechanism, wave traveling path and its attenuation characteristics in focal area or near field. In order to test its validity, we select the natural earthquakes and explosion or collapse events whose focus mechanisms vary obviously,and some natural earthquakes located at the same site or in a very small area. The study indicates that the time frequency energy attenuation factors of the natural earthquakes are obviously different with that of explosion or collapse events, and the change of the time frequency energy attenuation factors is relatively stable for the earthquakes under the normal seismicity background. Using the above mentioned method, it is expected to offer a useful criterion for strong earthquake prediction by continuous earthquake observation.