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Search Results: 1 - 10 of 224185 matches for " R. Rosso "
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A complex geo-scientific strategy for landslide hazard mitigation – from airborne mapping to ground monitoring
D. Bocchiola ,R. Rosso
Advances in Geosciences (ADGEO) , 2008,
Abstract: The currently adopted approach to avalanche hazard mapping in northern Italy includes avalanche dynamic modelling, coupled with statistical analysis of snow depth at avalanche start. The 30-years and 300-years return period avalanches at a given site are modelled and their run out zone and pressure are evaluated. The snow depth in the avalanche release zone is assumed to coincide with the three days snow fall depth H72 featuring a return period of 30 years and 300 years, respectively. In the Italian alps only short series of observed snow depth are available, covering a period of 20 years or so, thus requiring a regional approach, or index value approach for the purpose of high return period quantile estimation. Based of former studies, here we apply the index value approach developed for the Lombardia region, in northern Italy, for hazard mapping in a particular avalanche site. A dynamic avalanche model is tuned using the runout data for two major observed avalanche events. Then, the 30-years and 300-years runout zone and dynamic pressure are calculated. It is then shown that the obtained hazard maps are more accurate than those obtained using the evaluation of H72 as deduced from distribution fitting in a single site.
A multi-level approach to flood frequency regionalisation
C. De Michele,R. Rosso
Hydrology and Earth System Sciences (HESS) & Discussions (HESSD) , 2002,
Abstract: A multi-level approach to flood frequency regionalisation is given. Based on observed flood data, it combines physical and statistical criteria to cluster homogeneous groups in a geographical area. Seasonality analysis helps identify catchments with a common flood generation mechanism. Scale invariance of annual maximum flood, as parameterised by basin area, is used to check the regional homogeneity of flood peaks. Homogeneity tests are used to assess the statistical robustness of the regions. The approach is based on the appropriate use of the index flood method (Dalrymple, 1960) in regions with complex climate and topography controls. An application to north-western Italy is presented. Keywords: homogeneity, multi-level approach, regionalisation, seasonality, scale invariance, similarity, tests
Transient catchment hydrology after wildfires in a Mediterranean basin: runoff, sediment and woody debris
R. Rosso, M. C. Rulli,D. Bocchiola
Hydrology and Earth System Sciences (HESS) & Discussions (HESSD) , 2007,
Abstract: The transient effect of forest fires on runoff, erosion and yield of woody biomass has been investigated by combining the experimental approach with mathematical models of hydrological processes. The case study is the Branega creek in Liguria, Italy, where a forest fire in August 2003 caused substantial changes to soil and vegetation, and left a considerable amount of woody debris on the ground. Immediately after the fire, rainfall simulator experiments in adjacent burned and unburned plots showed the extent to which fire had increased runoff and erosion rates. A distributed hydrological model using the tube-flux approach, calibrated on experimental measurements, has been used to investigate hill slope and channel erosion in a small sub-catchment, 1.5 ha in area, nested in the Branega basin. Simulation runs show that the model accommodates the observed variability of runoff and erosion under disturbed and undisturbed conditions. A model component describing the delivery of wood from hill slopes to the channel in post-fire conditions, validated against local survey data, showed that the removal and transport of woody biomass can be reproduced using an integrated hydrological approach. Hence, transient complexity after wildfires can be addressed by such an approach with empirically determined physically-based parameters.
Precipitation downscaling using random cascades: a case study in Italy
B. Groppelli, D. Bocchiola,R. Rosso
Advances in Geosciences (ADGEO) , 2010,
Abstract: We present a Stochastic Space Random Cascade (SSRC) approach to downscale precipitation from a Global Climate Model (hereon, GCMs) for an Italian Alpine watershed, the Oglio river (1440 km2). The SSRC model is locally tuned upon Oglio river for spatial downscaling (approx. 2 km) of daily precipitation from the NCAR Parallel Climate Model. We use a 10 years (1990–1999) series of observed daily precipitation data from 25 rain gages. Scale Recursive Estimation coupled with Expectation Maximization algorithm is used for model estimation. Seasonal parameters of the multiplicative cascade are accommodated by statistical distributions conditioned upon climatic forcing, based on regression analysis. The main advantage of the SSRC is to reproduce spatial clustering, intermittency, self-similarity of precipitation fields and their spatial correlation structure, with low computational burden.
An integrated simulation method for flash-flood risk assessment: 1. Frequency predictions in the Bisagno River by combining stochastic and deterministic methods
M.C. Rulli,R. Rosso
Hydrology and Earth System Sciences (HESS) & Discussions (HESSD) , 2002,
Abstract: A stochastic rainfall generator and a deterministic rainfall-runoff model, both distributed in space and time, are combined to provide accurate flood frequency prediction in the Bisagno River basin (Thyrrenian Liguria, N.W. Italy). The inadequacy of streamflow records with respect to the return period of the required flow discharges makes the stochastic simulation methodology a useful operational alternative to a regionalisation procedure for flood frequency analysis and derived distribution techniques. The rainfall generator is the Generalized Neyman-Scott Rectangular Pulses (GNSRP) model. The rainfall-runoff model is the FEST98 model. The GNSRP generator was calibrated using a continuous 7-years' record of hourly precipitation measurements at five raingauges scattered over the Bisagno basin. The calibrated rainfall model was then used to generate a 1000 years' series of continuous rainfall data at the gauging sites and a flood-oriented model validation procedure was developed to evaluate the agreement between observed and simulated extreme values of rainfall at different scales of temporal aggregation. The synthetic precipitation series were input to the FEST98 model to provide flood hydrographs at selected cross-sections across the river network. Flood frequency analysis of the annual flood series (AFS) obtained from these simulations was undertaken using L-moment estimations of Generalized Extreme Value (GEV) distributions. The results are compared with those determined by applying a regional flood analysis in Thyrrhenian Liguria and the derived distribution techniques to the Bisagno river basin. This approach is also useful to assess the effects of changes in land use on flood frequency regime (see Rosso and Rulli, 2002). Keywords: flood frequency, stochastic rainfall generator, distributed rainfall runoff model, derived distribution
Review of recent advances in index flood estimation
D. Bocchiola,C. De Michele,R. Rosso
Hydrology and Earth System Sciences (HESS) & Discussions (HESSD) , 2003,
Abstract: Index flood estimation for regional flood frequency analysis needs to be based on the information available. The most appropriate method depends on the specific application and its choice requires a problem-oriented analysis. This paper presents a simple theoretical framework to deal with index flood estimation for a specific river site. The methodological approaches available for the purpose are reviewed. For each, the information required is specified and the reliability of the estimate, particularly desirable in risk analysis and management, is discussed. Where flood observations are lacking, indirect estimation must be undertaken using scenarios including those commonly met in hydrological practice; generally, these depend on the amount and type of information available. For each scenario, the methodologies are outlined, in order of the expected degree of complexity. After a guided analysis, an investigator can adopt the method providing the best tradeoff between effort in collecting and handling data and the resultant reliability which can be expected. Keywords: direct and indirect methods, index flood estimation, reliability, scenarios.
An integrated simulation method for flash-flood risk assessment: 2. Effects of changes in land-use under a historical perspective
R. Rosso,M.C. Rulli
Hydrology and Earth System Sciences (HESS) & Discussions (HESSD) , 2002,
Abstract: The influence of land use changes on flood occurrence and severity in the Bisagno River (Thyrrenian Liguria, N.W. Italy is investigated using a Monte Carlo simulation approach (Rulli and Rosso, 2002). High resolution land-use maps for the area were reconstructed and scenario simulations were made for a pre-industrial (1878), an intermediate (1930) and a current (1980) year. Land-use effects were explored to assess the consequences of distributed changes in land use due to agricultural practice and urbanisation. Hydraulic conveyance effects were considered, to assess the consequences of channel modifications associated with engineering works in the lower Bisagno River network. Flood frequency analyses of the annual flood series, retrieved from the simulations, were used to examine the effect of land-use change and river conveyance on flood regime. The impact of these effects proved to be negligible in the upper Bisagno River, moderate in the downstream river and severe in the small tributaries in the lower Bisagno valley that drain densely populated urban areas. The simulation approach is shown to be capable of incorporating historical data on landscape and river patterns into quantitative methods for risk assessment. Keywords: flood, simulation, distributed model, land-use changes, channel modifications, historical data
Deformaciones en el hormigón por fluencia para un estado tensional discontinuo con el tiempo
Rosso Ródenas, José Ramón
Informes de la Construccion , 1980,
Abstract: Public Works Technical Engineer The overlap principle admitted in the CEB-FIP 1970 Recommendations and in the EH-68 is not valid for deformation formulae due to creep, of the present instructions EH-73 and EP-77, and it represents a serious setback when designing a structure when loads are acting that have a discontinuous way in time. The purpose of this article is to arbitrate a method that will enable us to calculate a creep curve for an intermediary discharge that fulfils the overlap principle, admitting the load creep curve and the deferred elastic deformation one for total compliance with the EH-73 and EP-77. El principio de superposición admitido en las Recomendaciones del CEB-FIP de 1970 y en la EH-68 no es válido para las fórmulas de deformaciones por fluencia de las actuales Instrucciones EH-73 y EP-77, por lo que constituye un grave inconveniente para proyectar una estructura cuando actúan cargas de una manera discontinua con el tiempo. El objeto de este artículo es el de arbitrar un método que nos permita calcular una curva de fluencia para una descarga intermedia que cumpla con el principio de superposición, admitiendo como ciertas la curva de fluencia de carga y la de deformación elástica diferida para descarga total de las EH-73 y EP-77.
Cercos perimetrales en piezas comprimidas de sección circular
Rosso Ródenas, José Ramón
Informes de la Construccion , 1982,
Abstract: Not available. Se da una regia práctica que, de acuerdo con el dimensionamiento de cercos de a EH-80, permite el cálculo inmediato de cercos perimetrales en piezas comprimidas de hormigón armado.
An Econometric Analysis for the Behavior of the Bid-Ask Spread  [PDF]
H. de la Fuente-Mella, R. Campos-Espinoza, B. Silva-Palavecinos, D. Cademartori-Rosso
Open Journal of Social Sciences (JSS) , 2013, DOI: 10.4236/jss.2013.17001

Information asymmetries are an important element in the functioning of capital markets. An indirect means of measuring information asymmetry is through the spread of stock prices. The purpose of this paper is to identify the explanatory variables and the determinants of the bid-ask spread and to quantify the influence that the actors involved in the brokering of publically offered securities may have over the spread. The methodology used to model the time series for each of the analyzed companies is based on a time series from each of the observed econometric multivariate processes. The analysis shows a significantly negative relationship between the spread and the market-maker size, calculated in terms of both the equity and the stock portfolio; likewise, activity is measured by observing the amount offered for purchase and/or sale.

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