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1.
A step‐by‐step approximate procedure taking into consideration high‐frequency modes, usually neglected in the modal analysis of both classically and non‐classically damped structures, is presented. This procedure can be considered as an extension of traditional modal correction methods, like the mode‐acceleration method and the dynamic correction method, which are very effective for structural systems subjected to forcing functions described by analytical laws. The proposed procedure, herein called improved dynamic correction method, requires two steps. In the first step, the number of differential equations of motion are reduced and consequently solved by using the first few undamped mode‐shapes. In the second step, the errors due to modal truncation are reduced by correcting the dynamic response and solving a new set of differential equations, formally similar to the original differential equations of motion. The difference between the two groups of differential equations lies in the forcing vector, which is evaluated in such a way as to correct the effects of modal truncation on applied loads. Copyright © 2001 John Wiley & Sons, Ltd. 相似文献
2.
Fazio Eugenio Punturo Rosalda Cirrincione Rosolino Kern Hartmut Pezzino Antonino Wenk Hans-Rudolf Goswami Shalini Mamtani Manish A. 《International Journal of Earth Sciences》2017,106(7):2259-2278
International Journal of Earth Sciences - In the geologic record, the quartz c-axis patterns are widely adopted in the investigation of crystallographic preferred orientations (CPO) of naturally... 相似文献
3.
Luca Cavallaro Antonino Viviano Giovanni Paratore Enrico Foti 《Ocean Science Journal》2018,53(3):461-474
Surface wave interaction with aquatic vegetation appears to play a key role in coastal hydro-morpho-dynamics. As an example, the presence of a dense meadow at intermediate water depth is usually associated with a stable and resilient shore. Wave-meadow interactions are investigated here by means of physical modelling, with a focus on wave height distribution and hydrodynamics. The central part of a wave flume is covered by flexible artificial seagrass, composed of polyethylene leaves. This vegetation is tested in both near emergent and submerged conditions. The wave height reduction is evaluated by means of a drag coefficient defined from linear wave theory, which contains all the unknowns of the adopted methodology. The behaviour of such a coefficient is investigated as a function of a wave related Reynolds number. The influence of the flexibility of the leaves is also considered, together with a wave frequency parameter. The results show a complex behaviour with three different trends for near rigid, intermediate or highly flexible leaves. Amplitudes of the orbital velocities are investigated and show a fairly good match with the linear wave theory. On the contrary, the mean velocity along the water column appears to be modified by the seagrass for submerged leaves. 相似文献
4.
Germana Barone Mauro Francesco La Russa Antonino Lo Giudice Paolo Mazzoleni Antonino Pezzino 《Environmental Geology》2008,55(3):499-504
The Cathedral of St. Giorgio in Ragusa Ibla (Sicily) is one of the most important Baroque monuments of eastern Sicily. The restoration of the monument underway has put forward notable questions regarding the stone materials used and their state of degradation. The façade appears to be made mainly of a creamy white calcarenite, and of mortars and plasters. However, detailed analysis has highlighted a more complex use of the raw material. The mortar and plaster have a different composition in regards to their architectural use while the natural stone material is distinguished not only by a creamy-white calcarenite but also by a dark coloured bituminous calcarenite (pitch rock), which now appears whiter because of superficial chromatic alterations. This process was reproduced in the laboratory using an accelerated aging technique on samples of bituminous calcarenite, which allowed the cause of the alternation to be identified as photo-oxidation of the asphaltenes. Following this process of photo-oxidation, other forms of chromatic alterations affected the façade (brown–orange-coloured patinas). FTIR, Scanning Electron Microscope and thin section microscopic observation allowed the characterization of also the products of this process to be carried out, highlighting the complex mechanism which the processes underwent. 相似文献
5.
Rosolino Cirrincione Gaetano Ortolano Antonino Pezzino Rosalda Punturo 《Lithos》2008,103(3-4):466-502
The metamorphic evolution of a key sector of the western Mediterranean internal Alpine orogenic belt (southern Calabrian Peloritani Orogen) is identified and described by means of P–T pseudosections calculated for selected metapelite specimens, showing evidence of multi-stage metamorphism.Attention focused on the two lowermost basement nappes of the Aspromonte Massif (southern Calabria), which were differently affected by poly-orogenic multi-stage evolution. After a complete Variscan orogenic cycle, the upper unit (Aspromonte Peloritani Unit) was involved in a late-Alpine shearing event. In contrast, the several underlying metapelite slices, here grouped together as Lower Metapelite Group, show exclusive evidence of a complete Alpine orogenic cycle.In order to obtain reliable P–T constraints, an integrated approach was employed, based on: a) garnet isopleth thermobarometry; and b) theoretical predictions of the P–T stability fields of representative equilibrium assemblages. This approach, which takes into account the role of the local equilibrium volumes in controlling textural developments, yielded reliable information about P–T conditions from early to peak metamorphic stages, as well as estimates of the retrograde trajectory in the pseudosection P–T space.According to inferred detailed P–T paths, the evolution of the Aspromonte Peloritani Unit is characterised by a multi-stage Variscan cycle, subdivided into an early crustal thickening stage with P–T conditions ranging from 0.56 ± 0.05 GPa at 570 ± 10 °C to 0.63–0.93 GPa at 650–710 °C (peak conditions) and evolving to a later crustal thinning episode in lower P–T conditions (0.25 GPa at 540 °C), as documented by the retrograde trajectory.Conversely, the prograde evolution of the rocks of the Lower Metapelite Group shows evidence of a HP-LT early Alpine multi-stage cycle, with P–T evolving from 0.75–0.90 GPa at 510–530 °C towards peak conditions, with pressure increasing northwards from 1.12 ± 0.02 GPa to 1.24 ± 0.02 GPa, and temperatures of 540–570 °C.A late-Alpine mylonitic overprint affected the rocks of both the Aspromonte Peloritani Unit and the Lower Metapelite Group. This overprint was characterised by an initial retrograde decompression trajectory (0.75 ± 0.05 GPa at 570–600 °C), followed by a joint cooling history, ranging from 0.38 ± 0.14 at temperature from 450 to 520 °C.These inferred results were then used: a) to interpret the Lower Metapelite Group as a single crystalline basement unit exclusively affected by a complete Alpine orogenic cycle, according to the very similar features of P–T paths, comparable petrography and analogous structural characteristics; b) as a tool for more reliable correlations between the Aspromonte Massif, the other Calabrian terranes and the north African Orogenic Complexes. They may therefore consider a contribution to the geodynamic modelling of the western Mediterranean. 相似文献
6.
Vegetation response to rainfall seasonality and interannual variability in tropical dry forests 
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下载免费PDF全文 Rodolfo Souza Xue Feng Antonio Antonino Suzana Montenegro Eduardo Souza Amilcare Porporato 《水文研究》2016,30(20):3583-3595
Projected changes in rainfall seasonality and interannual variability are expected to have severe impacts on arid and semi‐arid tropical vegetation, which is characterized by a fine‐tuned adaptation to extreme rainfall seasonality. To study the response of these ecosystems and the related changes in hydrological processes to changes in the amount and seasonality of rainfall, we focused on the caatinga biome, the typical seasonally dry forest in semi‐arid Northeast Brazil. We selected four sites across a gradient of rainfall amount and seasonality and analysed daily rainfall and biweekly Normalized Difference Vegetation Index (NDVI) data for hydrological years 2000 to 2014. Rainfall seasonal and interannual statistics were characterized by recently proposed metrics describing duration, timing and intensity of the wet season and compared to similar metrics of NDVI time series. The results show that the caatinga tends to have a more stable response with longer and less variable growing seasons (3.1 ± 0.1 months) compared to the duration wet seasons (2.0 ± 0.5 months). The ecosystem ability to buffer the interannual variability of rainfall is also evidenced by the stability in the timing of the growing season compared to the wet season, which results in variable delays (ranging from 0 to 2 months) between the peak of the rainfall season and the production of leaves by the ecosystem. The analyses show that the shape and size of the related hysteresis loops in the rainfall–NDVI relations are linked to the buffering effects of soil moisture and plant growth dynamics. Finally, model projections of vegetation response to different rainfall scenarios reveal the existence of a maximum in ecosystem productivity at intermediate levels of rainfall seasonality, suggesting a possible trade‐off in the effects of intensity (i.e. amount) and duration of the wet season on vegetation growth and related soil moisture dynamics and transpiration rates. Copyright © 2016 John Wiley & Sons, Ltd. 相似文献
7.
Cristina M. Belfiore Mauro F. La Russa Paolo Mazzoleni Antonino Pezzino Marco Viccaro 《Environmental Earth Sciences》2010,61(5):995-1003
This paper presents new petro-chemical data on some typical mortars found in many buildings in the historic city centre of Catania (Eastern Sicily). Extensively used in the architecture of the city from the second half of the nineteenth century until the mid-twentieth century, these mortars are characterised by a particular aggregate locally known as “agghiara” or “ghiara”. This is the product of thermal transformation induced by the heating undergone by palaeo-soils, originally rich in organic matter, covered by lava flows, which change their colour to reddish nuances. The volcanic origin of ghiara is a peculiar feature of the Etnean area. Mixed with lime, it gives to mortars an intense reddish colour, as well as hydraulic properties, which are comparable with those of the historically used pozzolana. This work aimed at complete characterisation of these ghiara mortars, for providing information on several important technological aspects. In order to get information on used raw materials, sampling of some ancient underground quarries, located both in the historic city centre and at the periphery, was also performed. Results led to the complete characterisation of the selected ghiara mortars and yielded information on some technological features and the composition of both newly formed and secondary phases, these latter due to alteration processes. The hydraulic properties of mortars have been related to the occurrence of amorphous phases within the ghiara aggregate, which were identified by means of SEM morphological observations. These phases, formed during the “firing” process of palaeo-soils, react with lime producing hydraulic compounds (C–S–H and C–A–H), which are responsible for the mortars durability. 相似文献
8.
Rosalda Punturo Laura G. Russo Antonino Lo Giudice Paolo Mazzoleni Antonino Pezzino 《Environmental Geology》2006,50(2):156-169
An archaeometric study of the stone materials employed in the Late Baroque historical monuments of the ancient city centre of Catania was carried out. Lithological maps of a selection of monuments, transferred to a digital format, revealed that the stone materials are both magmatic and sedimentary rocks, the colours of which are matched in a peculiar type of bichromy. Particular attention focused on sedimentary rocks, which consist of various types of limestone quarried near the city of Syracuse (Hyblean Plateau, south-eastern Sicily). Carbonate rocks were characterised in terms of mineralogy, petrography and geochemistry, by studying rock samples from both monuments and historical extraction sites. Results showed that, although only one name was historically attributed to the above lithotypes (i.e. “Pietra di Siracusa‘’), they were quarried from many locations and, as they belong to various geological formations, they therefore exhibit great variety. In order to examine the durability of Hyblean limestones employed in works of cultural heritage interest, salt crystallisation tests were carried out according to standard procedure norms (UNI EN 12370 (1999) Determination of resistance to crystallisation of salts, 6p). Results are consistent with the forms of deterioration observed in the monuments, and highlight the close relationship between textural characteristics and damage. Our purpose is to provide a basic tool, which may be useful both for conserving monuments of cultural heritage and for their restoration. 相似文献
9.
Antonino D’Andrea Salvatore Cafiso Antonio Condorelli 《Pure and Applied Geophysics》2005,162(4):767-782
The recent earthquakes in California and Japan have shown the fundamental role that the road infrastructure plays in emergencies. In fact, only the maintenance of a sufficient level of efficiency can help to quickly reach the affected areas and thus avoid further serious consequences. The necessity of guaranteeing the functionality of the transport network during seismic events therefore requires seismic risk planning extended also to the road infrastructures in order to support the management of post-earthquake emergencies. Analogously it is fundamentally important to have analysis instruments of the road system able to preventatively evaluate the effects of earthquakes in order to identify possible emergencies, therefore preparing a program of intervention to reduce seismic risk on road networks. This paper proposes a methodology for the evaluation of seismic risk of road infrastructures according to the following points:Study of seismic hazard of the site for the definition of a seismic scenario using attenuation models in relation to historical seismology and the geological and tectonic characteristics of the territory;Analysis of the direct exposure connected to the probability of the presence of road users on the different parts of the network directly exposed to the seismic event;Analysis of the indirect exposure relative to the distribution of the population and the infrastructures for which post-earthquake accessibility must be guaranteed;Evaluation of the functional vulnerability in relation to the potential replaceability of damaged stretches considering network configuration and geometrical characteristics;Evaluation of structural vulnerability of the stretch correlated to the characteristics (structural, mechanical, technological, etc.) of the different components (bridges, embankments, trenches, tunnels) that make up the stretches obtained by the use of correctly elaborated tables for each component.The determination of global risk indexes of the single stretches and of the network, evaluated by means of a relationship between the ascertained parameters derived from the investigation of the previous points, provides the necessary information for the definition of mitigation measures to reduce the risk and for management planning before and after disaster. The proposed methodology, which has already been applied to a restricted area, is currently being applied to the province of Catania (Sicily, Italy), which is one of the geographical regions of highest seismic risk in Europe, and its future extension to all of eastern Sicily is foreseeable. 相似文献
10.
Giusj Valentina Fichera Cristina Maria Belfiore Mauro Francesco La Russa Silvestro Antonio Ruffolo Donatella Barca Riccardo Frontoni Giuliana Galli Antonino Pezzino 《Geoarchaeology》2015,30(2):79-99
Roman mortars were collected from the Villa dei Quintili in Rome, an archaeological site consisting of numerous edifices from nine construction phases dating from the 2nd century A.D. to modern times. A multianalytical approach was used on 34 mortar samples to infer the evolution of production techniques over time and to identify the source area of calcareous raw materials used in the preparation of the lime. Optical microscopy, scanning electron microscopy coupled with an energy‐dispersive system, and laser ablation inductively coupled plasma mass spectrometry were used to study the samples. The major and trace element data were compared with the compositions of two types of limestone samples (Calcare Massiccio and Calcare Maiolica) collected from the Cornicolani Mountains. The results suggest that the technological practices and the calcareous raw materials used for lime production remained unchanged over the time period considered (2nd century A.D. to 3rd century A.D.). The compositions of lime‐related particles in the mortars match those of Calcare Maiolica, which suggests its use as raw material for lime production. On the whole, the results are in agreement with data from existing literature regarding both the use by Roman builders of specific raw materials for the mortars’ production and the relative supply area. 相似文献