Consulta: subjectFacets:"Stochastic models"
Registros recuperados: 6
Data/hora: 16/06/2024 00:40:42

Development of private insurance schemes as a means to reduce water overexploitation during drought events. A case study in Campo de Cartagena (Segura River Basin, Spain)
Provedor de dados: 31
Autores: Perez Blanco,   Carlos Dionisio; Gomez Gomez,   Carlos Mario.
Water is a key input in the production of many goods and services and under certain conditions can become a critical limiting factor with significant impacts on regional development. This is the case of many agricultural European Mediterranean basins, where water deficit during drought events is partially covered by illegal abstractions, mostly from aquifers, which are tolerated by the authorities. Groundwater overexploitation for irrigation has created in these areas an unprecedented environmental catastrophe that threatens ecosystems sustainability, urban water supply and the current model of development. Market-based drought insurance systems have the potential to introduce the necessary incentives to reduce overexploitation during drought events and...
Tipo: Presentation
Palavras-chave: Drought insurance; Stochastic models; Groundwater; Agriculture; Risk and Uncertainty; Q15; Q18; Q25; Q51; Q58.
Ano: 2012
URL: http://purl.umn.edu/122453

Food security policy in a stochastic world
Provedor de dados: 31
Autores: Adelman,   Irma; Berck,   Peter.
Food security may be increased by variance-reducing strategies, by food aid, or by development strategies. This paper uses a Korea CGE model, subjected to random fluctuation in world-prices and domestic food productivity, to evaluate these policies. We find that poverty-reducing development strategies are the most effective food-security strategies.
Tipo: Working or Discussion Paper
Palavras-chave: Agricultural policies; Food aid; Prices; Risk; Stochastic models.
Ano: 1989
URL: http://purl.umn.edu/43664

Mathematical modeling and simulation of hourly precipitation through rectangular pulses - doi: 10.4025/actasciagron.v33i4.7052
Provedor de dados: 1
Autores: Uggioni, Edison; Universidade do Extremo Sul Catarinense; Back, Álvaro José; Empresa de Pesquisa Agropecuária e Extensão Rural de Santa Catarina; Vieira, Hamilton Justino; Empresa de Pesquisa Agropecuária e Extensão Rural de Santa Catarina.
The recorded historical series of precipitation are usually available for short periods of time and with many failures. The use of mathematical modeling to simulate rainfall is a tool used to circumvent this problem and to simulate the operation of water systems in different scenarios. The present study applies mathematical modeling to the hourly pluviometric precipitation data simulation.  A pluviographical data set from October 1980 to December 2007 was used in the study.  Precipitation data sets were obtained through daily pluviometric digitalization from the Meteorologic Station of Epagri at Urussanga, in southern Santa Catarina, Brazil (latitude 28º 31’ S and longitude 48º 19’ W).  To simulate the hourly rain series, the stochastic model was modified...
Tipo: Pesquisa aplicada
Palavras-chave: 5.03.02.00-0 Hydrology; Rainfall; Simulation; Probability; Stochastic models engenharia de Água e Solo Hydrology; Rainfall; Simulation; Probability; Stochastic models.
Ano: 2011
URL: http://periodicos.uem.br/ojs/index.php/ActaSciAgron/article/view/7052

Clinical signs of pneumonia in children: association with and prediction of diagnosis by fuzzy sets theory
Provedor de dados: 56
Autores: Pereira,J.C.R.; Tonelli,P.A.; Barros,L.C.; Ortega,N.R.S.
The present study compares the performance of stochastic and fuzzy models for the analysis of the relationship between clinical signs and diagnosis. Data obtained for 153 children concerning diagnosis (pneumonia, other non-pneumonia diseases, absence of disease) and seven clinical signs were divided into two samples, one for analysis and other for validation. The former was used to derive relations by multi-discriminant analysis (MDA) and by fuzzy max-min compositions (fuzzy), and the latter was used to assess the predictions drawn from each type of relation. MDA and fuzzy were closely similar in terms of prediction, with correct allocation of 75.7 to 78.3% of patients in the validation sample, and displaying only a single instance of disagreement: a...
Tipo: Info:eu-repo/semantics/article
Palavras-chave: Epidemiologic methods; Stochastic models; Fuzzy models; Clinical signs; Diagnosis; Data analysis.
Ano: 2004
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0100-879X2004000500012

Climatologie fine des systèmes de vagues pour l'étude des systèmes houlomoteurs
Provedor de dados: 5
Autores: Saulnier, Jean Baptiste.
This work focuses on the refinement of sea-states spectral characterisation in the frame of the development of wave energy converters (WECs). Until now, this characterisation has been limited to the consideration of basic global parameters such as the significant wave height and mean wave period. The present work namely underlines - thanks to simplified numerical models - that such a description is not sufficient to account for the performance of WECs, for they still exhibit a large variability in terms of mean production while wave energy and period are fixed. It is therefore needed to refine this description by introducing new wave characteristics, such as the wave groupiness, which is itself related to the sea-state's spectral bandwidth. The classical -...
Tipo: Text
Palavras-chave: Modèles stochastiques; Processus gaussiens; Simulations numériques; Cohérence spatio temporelle; Systèmes de vagues; Densité spectrale; État de mer; Largeur spectrale; Groupement de vagues; Systèmes houlomoteurs; Énergie des vagues; Stochastic models; Gaussian processes; Numerical simulations; Spatiotemporal coherence; Wave system; Spectral density; Sea state; Spectral bandwidth; Wave groupiness; WECs; Wave energy.
Ano: 2009
URL: http://archimer.ifremer.fr/doc/2009/these-7414.pdf

Deciphering the role of small-scale inhomogeneity on geophysical flow structuration: a stochastic approach
Provedor de dados: 5
Autores: Bauer, Werner; Chandramouli, Pranav; Chapron, Bertrand; Li, Long; Mémin, Etienne.
An important open question in fluid dynamics concerns the effect of smallscales in structuring a fluid flow. In oceanic or atmospheric flows, this is aptly captured in wave-current interactions through the study of the wellknown Langmuir secondary circulation. Such wave-current interactions are described by the Craik-Leibovich system, in which the action of a wave induced velocity, the Stokes drift, produces a so called “vortex force” that causes streaking in the flow. In this work, we show that these results can be generalized as a generic effect of the spatial inhomogeneity of the statistical properties of the small-scale flow components. As demonstrated, this is well captured through a stochastic representation of the flow.
Tipo: Text
Palavras-chave: Langmuir circulation; Baroclinic models; General circulation models; Stochastic models; Oscillations.
Ano: 2020
URL: https://archimer.ifremer.fr/doc/00610/72194/70975.pdf