Tsunami trapping near circular islands     

Stefano Tinti  Cesare Vannini 《Pure and Applied Geophysics》1995,144(3-4):595-619

Trapping of long water waves that are induced by submarine earthquakes and that attack circular islands is studied by applying a theoretical model (Tinti andVannini, 1994) that is based on the linear shallow water approximation. The solution is computed as the superposition of the eigenmodes of the water basin. The tsunami trapping is seen in terms of the capability of the source to excite the trapped eigenmodes of the basin. The bottom depth dependence around the island is shown to be quite important in determining the trapping capability of the island: a depth profile that is downwardly concave as the distance from the island coasts increases is substantially more efficient in amplifying the incoming waves and in trapping their energy than a profile exhibiting an upward concavity.  相似文献   

Spatio-temporal deposition profile of an experimentally produced turbidity current with a continuous suspension supply     

Shun Nomura  Giovanni De Cesare  Mikito Furuichi  Yasushi Takeda  Hide Sakaguchi 《国际泥沙研究》2022,37(3):299-306

A turbidity current is a turbulent, particle-laden gravity current that is driven by density differences resulting from the presence of suspended sediment particles. The current travels downslope, bearing a large amount of sediment over a great distance, and forms fluvial and submarine bedforms. Knowledge of the spatio-temporal deposition profile of turbidity-deposited sediment is important for a better understanding of sediment transport by turbidity currents. In the current study, the depositi...  相似文献   

H₃⁺ in diffuse interstellar gas     

Cesare Cecchi-Pestellini  Alexander Dalgarno 《Monthly notices of the Royal Astronomical Society》2000,313(1):L6-L8

A model is constructed of the material in front of the star Cygnus OB2 no. 12 in which dense cores are embedded in diffuse clumps of gas. The model reproduces the measured abundances of C₂ and CO, and predicts a column density of 910¹⁰ cm² for HCO⁺.  相似文献   

Shake table testing on restoring capability of double concave friction pendulum seismic isolation systems          下载免费PDF全文

Felice Carlo Ponzo  Antonio Di Cesare  Gianmarco Leccese  Domenico Nigro 《地震工程与结构动力学》2017,46(14):2337-2353

After an earthquake, non‐negligible residual displacements may affect the serviceability of a base isolated structure, if the isolation system does not possess a good restoring capability. The permanent offset does not affect the performance unless the design is problematic for utilities, also considering possible concerns related to the maintenance of the devices. Starting from experimental and analytical results of previous studies, the restoring capability of Double Concave Friction Pendulum bearings is investigated in this paper. A simplified design suggestion for the estimation of maximum expected residual displacements for currently used friction pendulum systems is then validated. The study is based on controlled‐displacement and seismic input experiments, both performed under unidirectional motion. Several shaking table tests have been carried out on a three‐dimensional isolated specimen structure. The same sequence of seismic inputs was applied considering three different conditions of sliding surfaces corresponding to low, medium and high friction. The accumulation of residual displacements is also investigated by means of nonlinear dynamic analysis. Copyright © 2017 John Wiley & Sons, Ltd.  相似文献   

A dynamic stiffness formulation for the analysis of secondary systems     

Dionisio Bernal 《地震工程与结构动力学》1999,28(11):1295-1308

Formulation of a frequency-domain substructure approach for the analysis of secondary systems is presented. The total system contemplated includes the primary structure, the secondary system, and the foundation medium, which is also treated as a substructure. A dynamic stiffness matrix in physical co-ordinates characterizes each one of the substructures. Elimination of the internal degrees of freedom of the primary structure prior to assembly of the equations for the coupled system is carried out with the aid of a truncated set of unconstrained normal modes. Accounting for the residual static flexibility of the truncated modes obviates potential problems of rank deficiency resulting from modal truncation. The formulation contemplates an arbitrary multi-component scattered motion at the soil–structure interface and imposes no limitations on the configuration of the primary or the secondary system. Connectivity between the systems is treated as an arbitrary linear relation between selected co-ordinates in each substructure. This feature is shown to be useful for modelling the commonly encountered situation where secondary systems are attached to torsionally eccentric structures. Copyright © 1999 John Wiley & Sons, Ltd.  相似文献   

Environmental and climatic conditions at a potential Glacial refugial site of tree species near the Southern Alpine glaciers. New insights from multiproxy sedimentary studies at Lago della Costa (Euganean Hills, Northeastern Italy)     

Petra Kaltenrieder  Claudio A. Belis  Simone Hofstetter  Brigitta Ammann  Cesare Ravazzi  Willy Tinner   《Quaternary Science Reviews》2009,28(25-26):2647-2662

It has been hypothesized that refugia of thermophilous tree species were located in Northern Italy very close to the Alps, though, this hypothesis has yet to be tested thoroughly. In contrast to Central and Southern Italy with its relative wealth of data, only a few fragmentary records are currently available from Northern Italy for the last Glacial (Würm, Weichselian). Our new study site Lago della Costa lies adjacent to the catchment of the megafans of the Alpine forelands and the braided rivers of the Northeastern Po Plain that have so far inhibited the recovery of continuous Glacial and Late-Glacial records. We analyze pollen, plant macrofossils, charcoal and ostracods to reconstruct the vegetation, fire and lake history for the period 33,000–16,000 cal. BP. We compare our data with Glacial records from Southern Europe to discuss similarities and dissimilarities between these potential refugial areas. A comparison with independent paleoclimatic proxies allows to assess potential linkages between environmental and climatic variability. New macrofossil and pollen data at Lago della Costa unambiguously document the local persistence of boreal tree taxa such as Larix decidua and Betula tree species around the study site during the last Glacial. The regular occurrence of pollen of temperate trees in the organic lake sediments (fine-detritus calcareous gyttja) suggests that temperate taxa such as Corylus avellana, Quercus deciduous, Tilia, Ulmus, Fraxinus excelsior, Carpinus, Abies alba and Fagus sylvatica, most likely survived the Last Glacial Maximum (LGM) at favorable sites in the Euganean Hills. The percentage values of temperate trees are comparable with those from Southern Europe (e.g. Monticchio in Southern Italy). We conclude that the Euganean Hills were one of the northernmost refugial areas of temperate taxa in Europe. However, the relative and absolute abundances of pollen of temperate trees are highly variable. Pollen-inferred declines of temperate tree communities (e.g. Quercetum mixtum) and low ostracod-inferred water levels at Lago della Costa correspond to the cold Heinrich events H-2 (LGM; 23,000–19,000 cal. BP) and H-3 (around 28,000 cal. BP), as recorded in the marine sediments of the North Atlantic. Similar patterns of significant temperate tree population collapses during cold Heinrich events are recorded at southern Mediterranean sites (e.g. Monticchio and the Alboran Sea). These findings suggest close linkages between Northern Atlantic and South-Central European climates during the past Glacial.  相似文献   

Comment on “Effect of surface wave inversion non-uniqueness on 1D seismic ground response analysis” by Roy et al.     

Alberto Pettiti  Sebastiano Foti  Cesare Comina 《Natural Hazards》2015,75(1):975-981

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Seismic characterization of shallow bedrock sites with multimodal Monte Carlo inversion of surface wave data     

Paolo Bergamo  Cesare Comina  Sebastiano Foti  Margherita Maraschini 《Soil Dynamics and Earthquake Engineering》2011

Sites with a limited overburden over a stiff basement are of particular relevance for seismic site response. The characterization of such stratigraphies by means of surface wave methods poses some difficulties in interpretation. Indeed the presence of sharp seismic contrasts between the sediments and the shallow bedrock is likely to cause a relevance of higher modes in the surface wave apparent dispersion curve, which must be properly taken into account in order to provide reliable results. In this study a Monte Carlo algorithm based on a multimodal misfit function has been used for the inversion of experimental dispersion curves. Case histories related to the characterization of stations of the Italian accelerometric network are reported. Spectral ratios and amplification functions associated to each site are moreover evaluated to provide an independent benchmark test. The results show the robustness of the inversion method in such non-trivial conditions and the possibility of getting an estimate of uncertainty related to solution non-uniqueness.  相似文献   

Two revolutions in the Earth Sciences   总被引：1，自引：0，他引：1  

Cesare Emiliani 《地学学报》1995,7(6):587-597

Two great revolutions have shaken the field of the geological sciences since World War II, one involving the solid Earth and the other involving the ice ages. The former came after a long and gradual preparation that extended across a century. The latter came abruptly, after a long period of stasis during which little conceptually new had emerged. The former did not demolish anything - it was only the logical conclusion of a long process of discovery. The latter demolished a canon that had become a dogma held true for half a century. The reactions of the scientists to the two revolutions are a study in contrast: instant acceptance of the former versus laggard and reluctant acceptance of the latter.  相似文献   

Modelling galaxy spectra in presence of interstellar dust – I. The model of interstellar medium and the library of dusty single stellar populations     

Lorenzo Piovan  Rosaria Tantalo  Cesare Chiosi 《Monthly notices of the Royal Astronomical Society》2006,366(3):923-944

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