Climate change impacts on extreme floods II: improving flood future peaks simulation using non-stationary frequency analysis   总被引：1，自引：1，他引：0  

Ousmane Seidou  Andrea Ramsay  Ioan Nistor 《Natural Hazards》2012,60(2):715-726

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Numerical and field study of ship-induced waves along the St. Lawrence Waterway,Canada     

Samir Gharbi  Georgi Valkov  Samir Hamdi  Ioan Nistor 《Natural Hazards》2010,54(3):605-621

Coastal and bank erosion along the St. Lawrence River Waterway in Quebec, Canada, represents a hazard to local communities living along the river banks, as well as to the local fauna habitat. The purpose of this study is to assess the potential impact of the waves generated by long containerships on riverbank erosion and recession at critical sites along the St. Lawrence River Waterway, which have already experienced significant damage. A field study was carried out to investigate the ship-generated hydrodynamics and the various driving mechanisms of the erosion process induced by ship waves. The field measurements provided an assessment of the influence of the length of large vessels by comparing the characteristics of the hydrodynamics fields induced by the passage of two containerships of different lengths. The potential for bank erosion and recession is assessed in terms of the wake erosive energy incident to the shoreline. The field data are compared against analytical results predicted by an empirical model, as well as against a ship-generated hydrodynamics model. Several numerical simulations for quantifying the ship’s drawdown and its effects are also presented.  相似文献   

Accuracy and sensitivity analysis for 54 models of computing hourly diffuse solar irradiation on clear sky     

Viorel Badescu  Christian A. Gueymard  Sorin Cheval  Cristian Oprea  Madalina Baciu  Alexandru Dumitrescu  Flavius Iacobescu  Ioan Milos  Costel Rada 《Theoretical and Applied Climatology》2013,111(3-4):379-399

Fifty-four broadband models for computation of solar diffuse irradiation on horizontal surface were tested in Romania (South-Eastern Europe). The input data consist of surface meteorological data, column integrated data, and data derived from satellite measurements. The testing procedure is performed in 21 stages intended to provide information about the sensitivity of the models to various sets of input data. There is no model to be ranked “the best” for all sets of input data. However, some of the models performed better than others, in the sense that they were ranked among the best for most of the testing stages. The best models for solar diffuse radiation computation are, on equal footing, ASHRAE 2005 model (ASHRAE 2005) and King model (King and Buckius, Solar Energy 22:297–301, 1979). The second best model is MAC model (Davies, Bound Layer Meteor 9:33–52, 1975). Details about the performance of each model in the 21 testing stages are found in the Electronic Supplementary Material.  相似文献   

Late Glacial and Holocene vegetation history in the southern part of Transylvania (Romania): pollen analysis of two sequences from Avrig     

Ioan Tantau  Maurice Reille  Jacques‐Louis de Beaulieu  Sorina Farcas 《第四纪科学杂志》2006,21(1):49-61

We present here the results of pollen analysis of two sequences of about 8.06 m and 11.90 m length, originating from two adjacent peat bogs in the southern part of Transylvania province, Romania (155 and 122 pollen spectra). The vegetation record, which is supported by 17 ¹⁴C dates, begins in the Late Glacial interstadial when forest recolonisation began with the development of Pinus, without a pioneer Betula phase. Picea began to expand from regional refuges. After a well‐defined Younger Dryas, the Holocene opens with the expansion of Betula, Ulmus and Picea, followed, at about 10 400 cal. yr BP, by Fraxinus, Quercus and Tilia. The Corylus optimum is correlated with the Atlantic chronozone (after 8600 cal. yr BP). The local establishment of Carpinus occurred at about 6500 cal. yr BP, with a maximum at about 5700 cal. yr BP. Fagus pollen is regularly recorded after 8200 cal. yr BP. This taxon became dominant at about 3700 cal. yr BP. The first indications of human activities appear at around 7200 cal. yr BP. Copyright © 2005 John Wiley & Sons, Ltd.  相似文献   

Evolution and Fragmentation of Wide-Angle Wind Driven Molecular Outflows     

Andrew Cunningham  Adam Frank  Peggy Varnière  Alexei Poludnenko  Sorin Mitran  Lee Hartmann 《Astrophysics and Space Science》2005,298(1-2):317-322

We present two dimensional cylindrically symmetric hydrodynamic simulations and synthetic emission maps of a stellar wind propagating into an infalling, rotating environment. The resulting outflow morphology, collimation and stability observed in these simulations have relevance to the study of young stellar objects, Herbig-Haro jets and molecular outflows. Our code follows hydrogen gas with molecular, atomic and ionic components tracking the associated time dependent molecular chemistry and ionization dynamics with radiative cooling appropriate for a dense molecular gas. We present tests of the code as well as new simulations which indicate the presence of instabilities in the wind-blown bubble’s swept-up shell.  相似文献   

A Summary of Instrumental Data on the Recent Strong Vrancea Earthquakes, and Implications for Seismic Hazard     

Horea Sandi  Ioan Sorin Borcia 《Pure and Applied Geophysics》2011,168(3-4):659-694

The paper is intended to summarize the most important instrumental data of direct relevance for engineering activities, obtained in connection with the strong Vrancea earthquakes of 4 March 1977, 30 August 1986, 30 May 1990, and 31 May 1990, and to point out some significant consequences and conclusions derived on this basis. Two main objectives of this analysis may be emphasized: (a) in-depth analysis of the radiation pattern; and (b) analysis of the spectral contents of ground motion in connection with the features of local conditions, and with the intention of assessing the relative importance of two main factors: source mechanism and long-distance wave propagation, versus features of local geological conditions. Some specific methodological developments used in this context may be mentioned: (a) use of a new approach to the quantification of ground motion intensity on the basis of instrumental (accelerographic) information; (b) analysis of radiation pattern in spectral and directivity terms; (c) parametric analysis of site-specific transfer functions for the local sequences of geological layers; and (d) a critical view on the outcome of post-earthquake survey techniques, keeping in view the implications of the spectral features of ground motion. The main results obtained are related to: (a) ground motion radiation features that have to be taken into account in connection with the data on the source mechanisms of the successive events dealt with; (b) expected spectral features of future strong ground motion at different sites; (c) methodological developments proposed for the assessment of local transfer functions; and (d) implications for microzonation activities.  相似文献   

The changing Romanian village: The case of semlac in Arad county, Romania     

Ioan Ianos Dr. 《GeoJournal》1996,38(2):175-179

Change in the village reflects the evolution of society and the conditions in the surrounding territory, including the neighbouring rural settlements and towns with which there is interaction. These considerations will determine the size and functions of a village, moving through centuries of change, often marked by violent events (invasions and wars; epidemics and natural disasters). So the search for equilibrium has often been frustrated by changing events. The paper concentrates on the upheavals associated with communism at the end of the Second World War, leading to the degradation of rural society, and the adjustments now being made in the light of the revolution of 1989. After the upheavals of the first transition years there are signs that prosperity is beginning to return to the villages as higher incomes from agriculture benefit the rural economy as a whole.  相似文献   

The summer surface urban heat island of Bucharest (Romania) retrieved from MODIS images     

Sorin Cheval  Alexandru Dumitrescu 《Theoretical and Applied Climatology》2015,121(3-4):631-640

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Simion Mehedinţi's Contribution to Modern Romanian Geography     

Ioan Ianoş  Radu Săgeată  Anthony Sorensen 《The Professional geographer》2018,70(3):504-512

Armed with a scholarship to find an answer to the question “What is geography?” Simion Mehedin?i's studies took him to continental Europe's three main centers of geographic thought: Paris, Berlin, and Leipzig. We explore how his innovative ideas flourished, especially in Leipzig under Ratzel. The first Romanian geographer, Mehedin?i, must be credited with having defined geography as a science of mutual relationships between geospheres. This thinking reached its pinnacle in two complex books, Terra and Ethnos, the contents of which we synthetically explore. We also trace the unfavorable historical and geopolitical conditions that led to this pioneering work being little recognized worldwide.  相似文献   

A guano‐derived δ13C and δ15N record of climate since the Medieval Warm Period in north‐west Romania          下载免费PDF全文

Daniel M. Cleary  Bogdan P. Onac  Ioan Tanţău  Ferenc L. Forray  Jonathan G. Wynn  Monica Ionita  Tudor Tămaş 《第四纪科学杂志》2018,33(6):677-688

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