262,434 research outputs found
I maestri dell'Architettura e del design: MARIO ZAFFAGNINI (DVD)
No full textL'autore (in collaborazione) cura il soggetto del video su supporto DVD "I maestri dell'Architettura e del Design: Mario Zaffagnini". Viene presentata l'opera del Prof. Arch. Mario Zaffagnini attraverso materiale iconografico alternato a videoriprese, documenti video d'epoca, interviste ai principali allievi, collaboratori e docenti di 5 scuole di Architettura Nazionali
Advanced distributed modelling of slope stability using root reinforcement and geostatistical parameterization of geotechnical soil properties
No full textA physically based model for shallow landslide triggering (HIRESSS - HIgh REsolution Soil Stability Simulator) was applied in a 100 km2 test site in Central Italy (Urbino, Marche region). The objectives were assessing the influence of additional cohesion provided by roots and testing the effectiveness of a geotechnical characterization performed in an another area, but on similar lithologies.
We performed two different simulations considering the rainfall event of January-February 2006, which triggered 14 landslides in the area. For both the simulations, rainfall data were fed into the model using the measurements at hourly time step of a nearby rain gauge station, while soil thickness was estimated using a state-of-the-art empirical model based on geomorphological parameters derived from curvature, slope gradient, lithology and relative position within the hillslope profile. Geotechnical input data were varied among the two simulations. In the first one, a few in-situ and laboratory tests were performed to characterize the main lithologies, while the remaining lithologies were characterized using literature data. In the second simulation, the main geotechnical and hydrological parameters (cohesion, internal friction angle, soil unit weight, hydraulic conductivity) were fed into the model using a geostatistical characterization performed on hundreds of measurements carried out in another Italian region, with similar lithologies. Furthermore, in the second simulation the additional cohesion provided by the plant roots was also taken into account.
The results obtained with the two simulations were validated considering the landslide dataset collected by field work and image interpretation shortly after the rainfall event studied. We discovered that the second simulation provided much more reliable results, with the areas surrounding the landslide locations characterized by much higher values of failure probability.
The outcome is very important to address future research in distributed slope stability modelling because it proved that: (i) additional root cohesion is an important factor that can be used to get more reliable results; (ii) when in need of characterizing the geotechnical parameters of the study area, instead of using just a few measurements performed therein, it is preferable to integrate also data coming from different areas but with similar lithologies if they were robustly characterized in geostatistical terms purposely for distributed slope stability studies
Going Beyond Counting First Authors in Author Co-citation Analysis
No full textThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Quantitative comparison between two different methodologies to define rainfall thresholds for landslide forecasting
No full textThis work proposes a methodology to compare the forecasting effectiveness of
different rainfall threshold models for landslide forecasting. We tested our
methodology with two state-of-the-art models, one using intensity–duration
thresholds and the other based on cumulative rainfall thresholds.
The first model identifies rainfall intensity–duration thresholds by means
of a software program called MaCumBA (MAssive CUMulative Brisk Analyzer)
(Segoni et al., 2014a) that analyzes rain gauge records, extracts intensity
(I) and duration (D) of the rainstorms associated with the initiation of
landslides, plots these values on a diagram and identifies the thresholds
that define the lower bounds of the I–D values. A back analysis using data
from past events is used to identify the threshold conditions associated
with the least number of false alarms.
The second model (SIGMA) (Sistema Integrato Gestione Monitoraggio Allerta) (Martelloni et al., 2012) is based on the
hypothesis that anomalous or extreme values of accumulated rainfall are
responsible for landslide triggering: the statistical distribution of the
rainfall series is analyzed, and multiples of the standard deviation
(σ) are used as thresholds to discriminate between ordinary and
extraordinary rainfall events. The name of the model, SIGMA, reflects the
central role of the standard deviations.
To perform a quantitative and objective comparison, these two models were
applied in two different areas, each time performing a site-specific
calibration against available rainfall and landslide data. For each
application, a validation procedure was carried out on an independent
data set and a confusion matrix was built. The results of the confusion
matrixes were combined to define a series of indexes commonly used to
evaluate model performances in natural hazard assessment. The comparison of
these indexes allowed to identify the most effective model in each case study and, consequently, which threshold should be used in the local early
warning system in order to obtain the best possible risk management.
In our application, none of the two models prevailed absolutely over the
other, since each model performed better in a test site and worse in the
other one, depending on the characteristics of the area.
We conclude that, even if state-of-the-art threshold models can be exported
from a test site to another, their employment in local early warning systems
should be carefully evaluated: the effectiveness of a threshold model
depends on the test site characteristics (including the quality and quantity
of the input data), and a validation procedure and a comparison with alternative models
should be performed before its implementation in operational early warning systems
Statistical and environmental analyses for the definition of a regional rainfall threshold system for landslide triggering in Tuscany (Italy)
No full textThe aim of this work is the determination of regional-scale rainfall thresholds for the triggering of landslides in the Tuscany Region (Italy). The critical rainfall events related to the occurrence of 593 past landslides were characterized in terms of duration (D) and intensity (I). I and D values were plotted in a log-log diagram and a lower boundary was clearly noticeable: it was interpreted as a threshold representing the rainfall conditions associated to landsliding. That was also confirmed by a comparison with many literature thresholds, but at the same time it was clear that a similar threshold would be affected by a too large approximation to be effectively used for a regional warning system. Therefore, further analyses were performed differentiating the events on the basis of seasonality, magnitude, location, land use and lithology. None of these criteria led to discriminate among all the events different groups to be characterized by a specific and more effective threshold. This outcome could be interpreted as the demonstration that at regional scale the best results are obtained by the simplest approach, in our case an empirical black box model which accounts only for two rainfall parameters (I and D). So a set of thresholds could be conveniently defined using a statistical approach: four thresholds corresponding to four severity levels were defined by means of the prediction interval technique and we developed a prototype warning system based on rainfall recordings or weather forecasts. © 2012 Science China Press and Springer-Verlag Berlin Heidelberg
Landslides triggered by rainfall: A semi-automated procedure to define consistent intensity-duration thresholds
No full textIn this paper, a methodology to automate and standardize the identification of rainfall intensity-duration thresholds for landslides triggering is presented. A newly developed software called MaCumBA (MAssive CUMulative Brisk Analyzer) can be used to analyze rain-gauge records, extract the intensities (I) and durations (D) of the rainstorms associated with the initiation of landslides, plot these values on a diagram and identify thresholds that define the lower bounds of the aforementioned I- D values. Because the methodology is automated, it is possible to process a relevant amount of data in short times, while allowing for user decision input. A back analysis using data from past events that did not trigger landslides can be used to identify the threshold conditions associated with the least amount of false alarms. We applied the methodology in two test sites. A validation procedure returned satisfactory results, demonstrating the potential utility of the proposed methodology in the development of landslide warning systems. © 2013 Elsevier Ltd
Il Plantario delle aste fluviali in Provincia di Firenze - Un catasto fiumi per il controllo e la mitigazione delle pericolosità di collasso arginale dell’Arno e dei suoi principali affluenti
No full textIl Plantario delle Aste fluviali è il risultato di un progetto, svolto in collaborazione con il Dipartimento di Scienze della Terra dell’Università di Firenze, consistente nella mappatura e informatizzazione in ambiente GIS (acronimo di Geographical Information System) di tutte le emergenze sia fisiografiche, sia inerenti l’edificato, ricadenti nelle pertinenze fluviali dell’Arno e dei suoi principali affluenti per i tratti di rigurgito di piena o comunque recanti Opere Idrauliche di II Categoria ai sensi del RD 523/1904
Energia pulita e rinnovabile dal fiume Arno. I risultati di uno studio di fattibilità in provincia di Firenze
No full textThe paper considers the possibility to use the transversal hydraulic works to produce locally the hydroelectric powe
Protecting Animals 36: Author Witi Ihimaera
No full textIn this very special episode of Knowing Animals I am joined by beloved New Zealand author Witi Ihimaera. Witi has written many books featuring nonhuman animals. He offers us a non-colonial lens through which to think about the human/nonhuman relationship
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