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21.
Rosa Nappi Giuliana Alessio Giovanni Bronzino Carlo Terranova Giuseppe Vilardo 《Natural Hazards》2008,45(1):73-85
In this article the implementation and potential of the Seismotectonic Information System of the Campania Region (SISCam)
are described, in particular an application of this Web-based GIS system to the seismotectonic analysis of the Sannio area
(Southern Apennines) is performed. WEB-GIS technologies greatly contribute to both the environmental monitoring and the disaster
management of areas affected by high natural risks. Specifically the SISCam system has been developed with the aim of providing
easy access and fast diffusion, through Internet technology, of the most significant geological, geophysical, and territorial
data relative to the Campania Region. The Sannio area has been selected as our application example because it is among the
most active seismic regions in Italy. This portion of the Southern Apennines which was hit by the June 5, 1688 strong earthquake
(M
W = 6.7, CPTI 1999) and by some low- and moderate-energy seismic sequences (1990–1992, 1997), is characterized by a complex
inherited tectonic setting and low-tectonic deformation rates that hide the seismogenic sources position. Since this case
study turned out to be complicated, the use of the SIScam WEB-GIS has become indispensable because it allowed us to visualize,
integrate and analyze all the data available, in order to obtain an accurate and direct picture of the seismotectonic setting
of the area. Moreover, a different approach of data analysis was necessary, due to the lack of up-to-date neotectonic and
structural data; therefore, the operation of this GIS system enabled us to process and generate some original informative
layers, through image analysis, such as new structural lineaments represented on a map of the potential active faults of the
area, which has been the final result of our application, as a contribution to new knowledge about the local seismic risk
parameters. 相似文献
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本文用理想结构单元法对空间刚架结构进行了极限强度分析,理想结构单元法在于将结构分成最大可能的单元。以简单的形式归并几何非线性与材料非线性。按增量形式加载,直到达到极限强度。本文根据Rashed理论导出了对称的切向方程组,节省了存贮单元、改善了破坏准则的描述。算例结果与非线性有限单元法结果十分吻合。 相似文献
24.
A.F. Velegrakis M.I. VousdoukasA.M. Vagenas Th. KarambasK. Dimou Th. Zarkadas 《Coastal Engineering》2007
This short contribution reports the results of a field study on the nearshore characteristics of waves generated by both conventional and high speed passenger ferries. The field observations took place in the late summer of 2005, at a beach close to the port of Mytilene (Island of Lesbos, Greece), and involved the visual observation of ship waves, using digital video recordings and image processing techniques. The results showed that passage of the fast ferry was associated with a longer, more complex and energetic nearshore event; this event not only did include higher nearshore waves (up to 0.74 m) and was organised in different wave packets, but it was also an order of magnitude longer (∼ 680 s) than the conventional ferry event. Regarding the effects on beach sediment dynamics, the fast ferry waves were estimated to be very efficient in mobilising the nearshore sediments in contrast to those of the conventional ferry. The fast ferry service appears to generate daily prolonged nearshore events, which contain waves with higher energy than those expected from the normal summer wind wave regime of the area; these events also include some high and very steep waves, which can be particularly erosive. Therefore, fast ferry wakes may have considerable impacts on the seasonal beach sediment dynamics/morphodynamics and the nearshore benthic ecology, as well as they may pose significant risks to bathers, affecting the recreational use of the beaches exposed to fast ferry traffic. Finally, the study has shown that satisfactory field observations of the nearshore characteristics of ship-generated (and wind) waves can be obtained using inshore deployments of calibrated poles, digital video cameras and appropriate image processing algorithms. 相似文献
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基于矢量信号处理的水声定位系统 总被引:2,自引:1,他引:2
将传统的水声定位系统与矢量水听器相结合,设计了一种全新的轻便型长基线被动水声定位系统。介绍了系统的组成和工作原理,并结合近年来出现的矢量信号处理技术,设计了新的实时信号处理软件。经湖试和海试,系统的可行性得到了初步的验证。 相似文献
30.
Practical implementation of Hilbert-Huang Transform algorithm 总被引:12,自引:0,他引:12
Hilbert-Huang Transform (HHT) is a newly developed powerful method for nonlinear and non-stationary time series analysis. The empirical mode decomposition is the key part of HHT, while its algorithm was protected by NASA as a US patent, which limits the wide application among the scientific community. Two approaches, mirror periodic and extrema extending methods, have been developed for handling the end effects of empirical mode decomposition. The implementation of the HHT is realized in detail to widen the application. The detailed comparison of the results from two methods with that from Huang et al. (1998, 1999), and the comparison between two methods are presented. Generally, both methods reproduce faithful results as those of Huang et al. For mirror periodic method (MPM), the data are extended once forever. Ideally, it is a way for handling the end effects of the HHT, especially for the signal that has symmetric waveform. The extrema extending method (EEM) behaves as good as MPM, and it is better t 相似文献