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931.
932.
Enzo Rizzo Alfonso Santoriello Luigi Capozzoli Gregory De Martino Cristiano Benedetto De Vita Daniela Musmeci Felice Perciante 《Surveys in Geophysics》2018,39(6):1201-1217
The use of geophysical methods in metrology is a significant tool within the wide research topic of landscape archaeology context. Since 2011, the Ancient Appia Landscapes Project aims to recognize dynamics, shapes and layout of the ancient settlement located along the Appia road east of Benevento, and cyclical elements and human activities that influenced the choice of landscapes. The integration of geophysical data with an archaeological infra-site analysis allowed us to investigate the area of Masseria Grasso, about 6 km from Benevento (Campania region, Italy). In this framework, an archaeogeophysical approach (Geomagnetic and Ground Penetrating Radar) was adopted for detecting anomalies potentially correlated with buried archaeological evidences. The geomagnetic results have given a wide knowledge of buried features in a large survey highlighting significant anomalies associated with the presence of buildings, roads and open spaces. These geophysical results permitted us to define the first archaeological excavations and, successively, a detailed Ground Penetrating Radar approach has been provided highlighting the rooms and paved spaces. The overlap between archaeological dataset and geophysical surveys has also allowed recognizing the path of the ancient Appia road near the city of Benevento and hypothesize the settlement organization of the investigated area, which has been identified with the ancient Nuceriola. 相似文献
933.
934.
Matteo Vacchi Giovanni De Falco Simone Simeone Monica Montefalcone Carla Morri Marco Ferrari Carlo Nike Bianchi 《地球表面变化过程与地形》2017,42(1):42-54
Here we review the multiple interactions between the endemic Mediterranean seagrass, Posidonia oceanica, and coastal geomorphologic processes as an outstanding example of biogeomorphology, taking into account recent advances in the field. Seagrass meadows are among the most important elements for the functioning of marine coastal ecosystems, and represent a major focus for research and conservation. Being considered a priority habitat, P. oceanica meadows are protected by several European Union directives and national laws. In this paper we examine: the role of sedimentary features in controlling the development of the meadows; the interplay between P. oceanica leaf litter (i.e. beached necromass) cast ashore and erosional‐depositional processes on the beaches; the interactions between meadows and nearshore hydrodynamics, and; possible linkages between geomorphological features of the seafloor and the architecture of meadows. Finally, we provide perspectives for future research on P. oceanica and other Mediterranean seagrass meadows in a biogeomorphological context with specific reference to climate change. Copyright © 2016 John Wiley & Sons, Ltd. 相似文献
935.
Tiziana Rossetto Camilo De la Barra Crescenzo Petrone Juan Carlos De la Llera Jorge Vásquez Marco Baiguera 《地震工程与结构动力学》2019,48(8):867-887
This paper presents a comprehensive comparison of different dynamic and static approaches for assessing building performance under sequential earthquakes and tsunami. A 10-storey reinforced concrete seismically designed Japanese vertical evacuation structure is adopted as a case study for the investigation. The case study building is first assessed under sequential earthquake and tsunami nonlinear response history analyses: the first time this is done in the literature. The resulting engineering demand parameters are then compared with those obtained when the analysis procedure is systematically simplified by substituting different static approaches for the nonlinear response history analyses in both the earthquake and tsunami loading phases. Different unloading approaches are also tested for the cases when an earthquake pushover is adopted. The results show that an earthquake nonlinear response history analysis, followed by a transient free vibration and a tsunami variable depth pushover, provides the best alternative to full dynamic analyses in terms of accuracy and computational efficiency. This structural analysis combination is recommended and has the advantage that it does not require the tsunami inundation time history to be known in advance. The proposed double pushover approach is instead deemed only suitable for the collapse assessment of regular low to mid-rise buildings and for the development of collapse fragility functions. An important observation made is that sustained earthquake damage seems not to affect the tsunami resistance of the case study building when the fully dynamic analysis is carried out for the sequential loading. This observation will be the subject of future work. 相似文献
936.
State-of-the-art hydrological climate impact assessment involves ensemble approaches to address uncertainties. For precipitation, a wide range of climate model runs is available. However, for particular meteorological variables used for the calculation of potential evapotranspiration (ETo), availability of climate model runs is limited. It is preferred that climate model runs are considered coupled when calculating changes in precipitation and ETo amounts, in order to preserve the internal physical consistency. This results in constraints on the maximum ensemble size. In this paper, we investigate the correlation between climate change signals of precipitation and ETo. It is found that, for two medium-sized catchments in Belgium, uncoupling climate model runs used for calculation of change signals of precipitation and ETo amounts does not result in a significant bias for changes in extreme flow. With these results, future impact studies can be conducted with larger ensemble sizes, resulting in a more complete uncertainty estimation. 相似文献
937.
During a mainshock-aftershock (MSAS) sequence, there is no time to retrofit structures that are damaged by a mainshock; therefore, aftershocks could cause additional damage. This study proposes a new approach to develop state-dependent fragility curves using real MSAS records. Specifically, structural responses before and after each event of MSAS sequences are used to obtain statistical relationships among the engineering demand parameter prior to the seismic event (pre-EDP), the intensity measure of the seismic event (IM), and the engineering demand parameter after the seismic event (post-EDP). The developed fragility curves account for damage accumulation, providing the exceeding probability of damage state (DS) given the IM of the event and the DS of the structure prior to the seismic excitation. The UBC-SAWS model, which was developed for wood-frame houses in British Columbia, Canada, is considered as a case study application. Results indicate that for the examined structural typology, state-dependent fragility curves based on residual interstorey drift ratio (pre-EDP), peak ground velocity (IM), and maximum inter-storey drift ratio (post-EDP) are the best choice to characterise the cumulative damage effect. An illustration of the developed fragility curves is provided by considering a hypothetical MSAS scenario of a Mw 9.0 Cascadia mainshock triggering a Mw 6.0 crustal event in the Leech River fault, affecting wooden houses in Victoria, Canada. The MSAS scenario increases Yellow tags (restricted access) by 12.3% and Red tags (no access) by 4.8%. 相似文献
938.
Alluvial rivers are composed of self-formed channels which are sensitive to disturbances in their flow and sediment-supply regimes. Regime changes commonly occur over decadal and longer timescales and can be caused by anthropogenic alterations such as dam construction and removal. Advances in numerical modeling have increased our ability to explore geomorphic adjustments over long timescales; however, many models designed to be run for decades or longer assume that banks are immovable or that channel width is constant. Since river channels often respond to disturbance by adjusting their geometry, this is a significant shortcoming. To investigate the impact of long-term sediment supply alterations on channel geometry and stability, we have adapted MAST-1D, a reach-scale bed evolution model, to incorporate functions for bank erosion, vegetation encroachment, and local avulsions. The model is designed for medium-large, coarse multithreaded rivers and can be run over long (decades–centuries) timescales. Bank erosion is a function of the mobility and transport capacity for structurally-important grains which protect the bank toe. Vegetation growth is proportional to point bar width and occurs during conditions of low shear stress. Local avulsions occur when aggradation causes channel depth to drop below a threshold. We apply the model to the Elwha River in Washington, USA with the goal of investigating if and when the river recovers from dam emplacement and removal. The Elwha was dammed for nearly 100 years, and then two dams were removed, releasing a large pulse of sediment. We have modeled the set of reaches between the two dams. Our simulations suggest that channel response to dam emplacement occurs gradually over several decades but that the channel recovers to near pre-dam conditions within about a decade following the removal. The dams leave a lasting legacy on the floodplain, which does not completely recover, even after two centuries. © 2019 John Wiley & Sons, Ltd. 相似文献
939.
Meng Ding Ya-Peng Zhang Yong-Jie Zhang Yuan-Peng Wang Tie-Kuang Dong Antonio De Benedittis Paolo Bernardini Fang Fang Yao Li Jie Liu Peng-Xiong Ma Zhi-Yu Sun Valentina Gallo Stefania Vitillo Zhao-Min Wang Yu-Hong Yu Chuan Yue Qiang Yuan Yong Zhou Yun-Long Zhang 《天文和天体物理学研究(英文版)》2019,(3):145-154
The DArk Matter Particle Explorer(DAMPE) is a space-borne apparatus for detecting the highenergy cosmic-ray-like electrons, γ-rays, protons and heavy ions. The Plastic Scintillator Detector(PSD)is the top-most sub-detector of the DAMPE. The PSD is designed to measure the charge of incident highenergy particles and it also serves as a veto detector for discriminating γ-rays from charged particles. In this paper, a PSD on-orbit calibration procedure is described, which includes the five steps of pedestal, dynode correlation, response to minimum-ionizing particles, light attenuation function and energy reconstruction.A method for reconstructing the charge of incident high energy cosmic-ray particles is introduced. The detection efficiency of each PSD strip is verified to be above 99.5%; the total efficiency of the PSD for charged particles is above 99.99%. 相似文献
940.
近年来,针对中国生态环境、洪涝灾害应急响应、国土安全监测等遥感观测任务,无人航空遥感手段需求越来越多。构建异构无人航空器遥感观测多任务集群系统是近几年的发展目标,为完成无人航空遥感生态建设,垂直起降无人机以其不受场地限制起降又可快速巡飞的特点,在多个领域发挥着越来越大的作用。本文主要研究内容包括国内垂直起降无人机发展现状调研、面向航空遥感应用市场的无人机分析及典型机型介绍、垂直起降无人机在遥感领域的应用场景及案例分析、垂直起降无人机在遥感领域的应用前景及发展趋势等。通过广泛调研及深入分析可知,目前垂直起降固定翼无人机正逐步取代多旋翼飞行器的主导地位;垂直起降无人机占据了遥感应用无人机80.47%的市场份额;动力多元化、系统智能化、布局多样化、尺寸小型化等是面向遥感应用的垂直起降无人机的发展方向。本文较为全面地阐述和剖析了面向遥感应用的垂直起降无人机的相关内容,为遥感航空无人机生态建设提供了参考与支撑。 相似文献