1,721,207 research outputs found
Underwater geomorphology of the rocky coastal tracts between Finale Ligure and Vado Ligure (western Liguria, NW Mediterranean Sea)
No full textThe western part of the Liguria Region (NW Mediterranean Sea) has been reported as tectonically stable to slowly uplifting since the Late Pleistocene. Despite good knowledge of the coastal geomorphological features above sea level, very little information is available on the characteristics of the underwater coastlines. Direct and indirect underwater surveys carried out in the area between Vado Ligure and Finale Ligure (Western Liguria) allowed the identification of several surfaces of marine origin, in four sites, at three depth intervals: 8-13. m, 17-23. m and 27-30. m. These values appear to be in bathymetric analogy with those reported by other authors along the Italian coastlines, in areas where the tectonic movements along the Late Quaternary are considered negligible on the basis of the elevation of the MIS 5.5 shoreline. Although few chronological constraints are possible due to the lack of dateable material, the marine morphologies identified in this study constrain their ages to the Middle and Late Quaternary. © 2010 Elsevier Ltd and INQUA
Eustatic and Relative Sea Level Changes
No full textSea level changes can be driven by either variations in the masses or volume of the oceans, or by changes of the land with respect to the sea surface. In the first case, a sea level change is defined ‘eustatic’; otherwise, it is defined ‘relative’. Several techniques can be used to observe changes in sea level, from satellite data to tide gauges to geological or archeological proxies. Regardless of the technique used, ‘eustasy’ cannot be measured directly, but only calculated after perturbing factors of different origins are taken into account. In this paper, we review the meaning and main processes that contribute to eustatic and relative sea level changes, and we give an overview of the different techniques used to observe them
A standardized database of Last Interglacial (MIS 5e) sea-level indicators in Southeast Asia
Full text linkMarine Isotope Stage 5e (MIS 5e; the Last Interglacial, 125 ka) represents a process analog for a warmer world. Analysis of sea-level proxies formed in this period helps in constraining both regional and global drivers of sea-level change. In Southeast Asia, several studies have reported elevation and age information on MIS 5e sea-level proxies, such as fossil coral reef terraces or tidal notches, but a standardized database of such data was hitherto missing. In this paper, we produced such a sea-level database using the framework of the World Atlas of Last Interglacial Shorelines (WALIS; https://warmcoasts.eu/world-atlas.html). Overall, we screened and reviewed 14 studies on Last Interglacial sea-level indicators in Southeast Asia, from which we report 43 proxies (42 coral reef terraces and 1 tidal notch) that were correlated to 134 dated samples. Five data points date to MIS 5a (80 ka), six data points are MIS 5c (100 ka), and the rest are dated to MIS 5e. The database compiled in this study is available at 10.5281/zenodo.5040784 (Maxwell et al., 2021)
Virtual model of a mirror orientation mechanism in solar energy applications, to evaluate its pointing accuracy in presence of external excitations
No full textThe paper presents the preliminary results of a study performed at the MGMVLab / S.Ilario Solar Station of the University of Genoa on the use of a virtual model to evalu¬ate dynamic phenomena and pointing accuracy perturbations induced by external exci¬tations (due e.g. to wind or traffic) on the mirrors orienting mechanism in solar energy power plants. This clearly involves the balance between the structural flexibility of the mechanism due to cost reduction exigencies and the accuracy required for a proper op¬eration. Obviously also the supporting structure influence must be considered; the pre¬sent paper refers mainly to the pointing linkage.
The model analyzes a specific version of the Francia mechanism [1], the one adopted in the S.Ilario Solar Station of the Genoa University; it has been created using the Motion module of the LMS Virtual Lab software for multibody simulation. Due to the charac¬teristics of the system under examination, the “flexible body” module has been imple¬mented, making possible to consider as flexible some parts of the system in a multibody simulation, through an interface with a finite elements code.
The parts to be modeled as flexible have been individuated through an experimental modal analysis performed on a single mirror mechanism; its results showed the ele¬ments which mostly participate to the modeshapes of the low frequency flexural modes considered as the mostly critical. The experimental results have been also used to vali¬date the FEM models of the elements modeled and inserted into the multibody software
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Assessing enigmatic boulder deposits in NE Aegean Sea: Importance of historical sources as tool to support hydrodynamic equations
Full text linkDue to their importance in the assessment of coastal hazards, several studies have focused on geomorphological and sedimentological field evidence of catastrophic wave impacts related to historical tsunami events. Among them, many authors used boulder fields as important indicators of past tsunamis, especially in the Mediterranean Sea. The aim of this study was to understand the mechanism of deposition of clusters of large boulders, consisting of beachrock slabs, which were found on the southern coasts of Lesvos Island (NE Aegean Sea). Methods to infer the origin of boulder deposits (tsunami vs. storm wave) are often based on hydrodynamic models even if different environmental complexities are difficult to be incorporated into numerical models. In this study, hydrodynamic equations did not provide unequivocal indication of the mechanism responsible for boulder deposition in the study area. Further analyses, ranging from geomorphologic to seismotectonic data, indicated a tsunami as the most likely cause of displacement of the boulders but still do not allow to totally exclude the extreme storm origin. Additional historical investigations (based on tsunami catalogues, historical photos and aged inhabitants interviews) indicated that the boulders are likely to have been deposited by the tsunami triggered by the 6.7 M s Chios-Karaburum earthquake of 1949 or, alternatively, by minor effects of the destructive tsunami produced by 1956's Amorgos Island earthquake. Results of this study point out that, at Mediterranean scale, to flank numerical models with the huge amount of the available historical data become a crucial tool in terms of prevention policies related to catastrophic coastal events. © 2012 Author(s). CC Attribution 3.0 License
PALEO-SEAL: A tool for the visualization and sharing of Holocene sea-level data
No full textWe present PALEO-SEAL, a simple web interface that allows visualizing, querying and downloading Holocene sea-level datapoints formatted following the HOLSEA data template. The data is hosted on a mySQL database, and the interface uses AngularJS. PALEO-SEAL is scalable to large datasets and can be deployed in few easy steps, that require only basic knowledge of SQL and HTML. The tool is released in the open domain
- …
