Search results for "weibull"

Recurrence time distribution and temporal clustering properties of a cellular automaton modelling landslide events

2018

Abstract. Reasonable prediction of landslide occurrences in a given area requires the choice of an appropriate probability distribution of recurrence time intervals. Although landslides are widespread and frequent in many parts of the world, complete databases of landslide occurrences over large periods are missing and often such natural disasters are treated as processes uncorrelated in time and, therefore, Poisson distributed. In this paper, we examine the recurrence time statistics of landslide events simulated by a cellular automaton model that reproduces well the actual frequency-size statistics of landslide catalogues. The complex time series are analysed by varying both the threshold…

Fibre fragment distribution in a single-fibre composite tension test

2001

Abstract Single fibre fragmentation tests are performed for brittle fibres with Weibull strength distribution and different surface treatments. The fragmentation process is modelled and closed-form expressions for break spacing distribution are obtained. The model accounts for the effect of finite fibre length on the initial fragmentation as well as for break interaction on the advanced fragmentation stage. It is assumed that the exclusion zone due to fibre–matrix interface failure and stress recovery in the fibre is linearly dependent on the applied load. This assumption is validated experimentally. The derived theoretical average fragment length dependence on applied load is used to deter…

The individual determinants unemployment duration

1997

Si, aujourd'hui, les études sur les comportements des demandeurs d'emploi sur le marché du travail sont de plus en plus importantes, la modélisation de ces comportements comporte encore un bon nombre d'interrogations. Parmi celles-ci figure le problème du biais d'échantillonnage présent dans laplupart des données françaises sur les durées de chômage. Dans un précédent travail, nous avons montré l'importance et les conséquences de l'oubli du biais d'échantillonnage sur les probabilités conditionnelles de sortie du chômage. Dans le travail présenté ici et réalisé à partir de l'enquête « suivides chômeurs », notre intérêt porte sur les conséquences de l'oubli de ce biais sur les déterminants i…

Artichoke fibres as potential reinforcement of composite materials: mechanical and thermal characterization

2011

Demonstrating measure-correlate-predict algorithms for estimation of wind resources in central Finland

2010

In this study, measure-correlate-predict (MCP) algorithms - Simple Linear Regression and Variance Ratio Methods - for predicting wind speed were studied. The MCP algorithms were successfully used to predict missing wind speeds at two sites in Jyväskylä and Viitasaari, respectively. These two algorithms used data from one of the site to predict missing wind speed data at the other site. The results obtained using the MCP methods were compared using metrics that showed the characteristics of the predicted data to be unbiased compared to measured data. From the data of this study, we also evaluated wind power density at both sites which categorized the local wind resources as poor since the de…

Analisi del regime anemometrico a scala urbana della città di Palermo

2010

Allo scopo di valutare la possibilità di sfruttare l’energia eolica anche in zone fortemente urbanizzate recentemente la Comunità Europea ha posto tra le sue priorità scientifiche la redazione di atlanti eolici a piccola scala. Al fine di fornire dati che possano condurre ad una corretta valutazione eolica di centri urbani, nel seguente lavoro vengono analizzate le caratteristiche del regime anemometrico dell'area urbana di Palermo, registrate da un rete di monitoraggio automatica afferente al Dipartimento di Ricerche Energetiche ed Ambientali (DREAM) e composta da quattro stazioni meteo. Dopo un esame statistico preliminare, in cui le serie temporali della velocità del vento sono state div…

Estimation of wind velocity over a complex terrain using the Generalized Mapping Regressor

2010

Abstract Wind energy evaluation is an important goal in the conversion of energy systems to more environmentally friendly solutions. In this paper, we present a novel approach to wind speed spatial estimation on the isle of Sicily (Italy): an incremental self-organizing neural network (Generalized Mapping Regressor – GMR) is coupled with exploratory data analysis techniques in order to obtain a map of the spatial distribution of the average wind speed over the entire region. First, the topographic surface of the island was modelled using two different neural techniques and by exploiting the information extracted from a digital elevation model of the region. Then, GMR was used for automatic …