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C. S. Sandeep M. C. Todisco V. Nardelli K. Senetakis M. R. Coop S. D. N. Lourenco 《Acta Geotechnica》2018,13(6):1355-1367
In this paper, an experimental micromechanical study is presented investigating the contact mechanics and tribological behaviour of highly/completely decomposed tuff granules. The parent material was taken from two locations—named the top and bottom—from a recent landslide in Hong Kong, and in this study the tested granules were obtained from the parent material after drying and sieving processes. Basic material characterisation was conducted quantifying the particle shape, the surface roughness and the strength of a set of grains. A set of twenty-nine monotonic inter-particle shearing tests were conducted on pairs of granules taken from the top and bottom of the landslide. It was found that the granules had very high friction angles at their contacts, in general greater in comparison with other materials reported in the literature. The slightly greater inter-particle friction for the granules taken from the top of the landslide might be because of their higher roughness in comparison with the ones from the bottom. Additional experiments were conducted to investigate the normal and tangential load–displacement response of the granules subjected to cyclic loading. A good curve fitting for the normal load–displacement response could be obtained by using very low apparent Young’s moduli in the Hertzian model. In general, the decomposed tuff granules showed significant plastic response during the first normal load cycle, and this plastic behaviour continued for the subsequent third and fourth cycles. In the cyclic inter-particle shearing tests, the nonlinearity and hysteresis increased for larger cyclic displacements, but the effect of the number of shearing cycles on the energy loss was generally small. Finally, a limited discussion is presented on the applicability of a theoretical model on the tangential load–displacement behaviour of the granules. 相似文献
2.
This paper addresses oil spill detection from remotely sensed optical images. In particular, it focuses on the automatic classification
of regions of interest (ROIs) in two classes, namely oil spills or look-alikes. Candidate regions and the corresponding boundaries
have been manually identified from full resolution Moderate Resolution Imaging Spectroradiometer images, related to the Mediterranean
Sea over the years 2008 and 2009. Then, a set of features has been extracted from each ROI, allowing to formulate the oil
spill detection problem as a two-class classification task on the provided regions (i.e. using a supervised learning strategy).
Since ROI classification is challenging, some desired characteristics for the classification algorithm are first identified,
such as accuracy, robustness, etc. Then, a solution (called SVME) is provided: it is based on an ensemble of incremental/decremental
cost-oriented Support Vector Machines, aggregated with the Receiving Operating Characteristic (ROC) convex hull method in
the ROC space. Such a solution addresses all the desired characteristics. Finally, the results obtained on the collected dataset
are shown. The importance of this study is the devising of a powerful classification technique that may have an impact on
optical oil spill detection from space, especially if fused with satellite synthetic aperture radar data. Moreover, it is
shown how the proposed system can be used as a decision support tool, to help a junior operator in making more reliable detections. 相似文献
3.
Multiplatform observation of the surface circulation in the Gulf of Naples (Southern Tyrrhenian Sea) 总被引：1，自引：1，他引：0
Marco Uttieri Daniela Cianelli Bruno Buongiorno Nardelli Berardino Buonocore Pierpaolo Falco Simone Colella Enrico Zambianchi 《Ocean Dynamics》2011,61(6):779-796
The Gulf of Naples (Southern Tyrrhenian Sea) is a highly urbanised area, where human activities and natural factors (e.g.
river runoff, exchanges with adjacent basins) can strongly affect the water quality. In this work we show how surface transport
can influence the distribution of passively drifting surface matter, and more in general if and how the circulation in the
basin can promote the renovation of the surface layer. To this aim, we carried out a multiplatform analysis by putting together
HF radar current fields, satellite images and modelling tools. Surface current fields and satellite images of turbidity patterns
were used to initialise and run model simulations of particle transport and diffusion. Model results were then examined in
relation to the corresponding satellite distributions. This integrated approach permits to investigate the concurrent effects
of surface dynamics and wind forcing in determining the distribution of passive tracers over the basin of interest, identifying
key mechanisms supporting or preventing the renewal of surface waters as well as possible areas of aggregation and retention. 相似文献
4.
Castro G. B. Siacara A. T. Nardelli A. Lenzi L. Futai M. M. 《Geotechnical and Geological Engineering》2022,40(8):4121-4144
Geotechnical and Geological Engineering - Numerical modelling development for capillary barrier investigation considering unsaturated soil–geotextile interface has been studied and evaluated... 相似文献
5.
Medeiros ID Siebert MN de Toledo e Silva G Moraes MO Marques MR Bainy AC 《Marine environmental research》2008,66(1):156-157
In order to investigate the influence of domestic sewage on the gene expression of Pacific oysters Crassostrea gigas, suppression subtractive hybridization (SSH) method was employed. Oysters were sampled at a farming area and, after 10 days of acclimation in the laboratory, were exposed to untreated domestic sewage diluted 33% for 48 h. Gills of male oysters were excised for total RNA extraction. mRNA was purified and the differential gene expression was analyzed by SSH. We obtained 61 cDNA sequences but only 15 were identified, which includes fatty acid binding protein, multidrug resistance protein, omega glutathione S-transferase, cytochrome P450 isoform CYP356A1, among others. The identified genes are associated with different metabolic functions like biotransformation, membrane transport, aerobic metabolism and translational machinery, evidencing the potential toxic effects elicited by these effluents. 相似文献
6.
Zanette J Nunes FF Medeiros ID Siebert MN Mattos JJ Lüchmann KH Rodrigues de Melo CM Bainy AC 《Marine environmental research》2008,66(1):196-198
Oysters Crassostrea rhizophorae and Crassostrea gigas were kept for fourteen days at four sites in S?o José, SC, Brazil, chosen according to a sewage discharge contamination gradient. Enzymatic activities of CAT, GST, G6PDH and GR were evaluated in gills and digestive glands. Higher CAT activity was observed in tissues of C. rhizophorae in response to sewage contamination possibly indicating peroxisome proliferation induction. C. gigas showed elevated G6PDH activity in digestive gland, and GR in gills, after domestic sewage exposure. In conclusion, C. rhizophorae and C. gigas showed different biochemical responses after in situ exposure to domestic sewage. However, C. rhizophorae showed more significant changes in CAT suggesting that this organism could be a better monitor to this kind of effluent. 相似文献
7.
Maria Pia Nardelli Eleonora Fossile Olivier Péron Hélène Howa Meryem Mojtahid 《Boreas: An International Journal of Quaternary Research》2023,52(1):109-123
The recurrent latent-heat polynya characterizing Storfjorden (Svalbard, Norway) triggers seasonal formation of thin first-year sea ice. This leads to the production of dense, salty, and corrosive brines that cascade towards the sea floor and mix with shelf waters. The bottom topography of the fjord is responsible for the retention of these dense waters in two central deep basins throughout the year. Recent studies show that living benthic foraminifera in Storfjorden are particularly affected by the persistence of brines on the sea floor, with a strong dominance of agglutinated (A) species and high degrees of dissolution of calcareous(C) faunas. Therefore, the A/C ratio, calculated on living faunas, was proposed as a proxy for brine persistence. In the present study we analyse the fossil faunas, found below the taphonomically active zone, to investigate the residual signal of the A/C proxy after the intense early taphonomic processes and challenge its applicability in sedimentary archives. Our results show that despite the generally high taphonomic loss inside the fjord, a high proportion of agglutinated species is still visible in fossil faunas at the stations experiencing regular and/or persistent presence of brine-enriched shelf waters. These results support the application of the A/C ratio in historical records to reconstruct the persistence of brines and indirectly the first-year sea ice formation in Storfjorden. This can be further applied to other Arctic fjords with similar settings and characterized by the production of brines during the winter–early spring season. 相似文献
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