Concept ; Dynamic model ; Economic theory ; Fractal geometry ; Model ; Random process ; Statistics ; Stochastic model
The A. concludes that « in spite of its simplicity (no exogenous uncertainty, no inventories, no capital, etc.), the basic structure implies a highly complex nonlinear dynamic model which generates cycles of high order as well as irregular behavior
endogenously ». Application of the theory of fractals to Keynesian models. - (CN)
Coastal dynamics ; Coastal environment ; Marine abrasion ; Mathematical model ; Model
Les AA. proposent un modèle décrivant le stade initial (avant la formation de la falaise) de l'évolution du profil de l'avant-côte, appliqué à différentes variations du niveau.
This paper presents the second part of an exploration of the application of developments made in hydraulic floodplain modelling to ungauged flood forecasting. A two dimensional finite element model, RMA-2, is applied to a 25 km floodplain reach
Atmospheric circulation ; Climate ; Model ; Numerical model ; Regional climate ; Simulation
Présentation d'un nouveau modèle de simulation de la circulation atmosphérique, dont l'avantage est de faire ressortir des variations d'échelle régionale (maillage de 7 × 7 km, contre 15 × 15 dans les modèles antérieurs).―(JPB)
Hydrodynamics ; Hypsometry ; Mathematical model ; Runoff ; Russia ; Siberia ; Watershed
Etablissement d'un modèle hydrodynamique de l'écoulement. Description des caractéristiques bathygraphiques des micro-bassins-versants. Données concernant la Sibérie.
Arctique ; Modèle ; Modèle dynamique ; Russie ; Sol ; Température ; Toundra ; Zone froide
Arctic Region ; Cold area ; Dynamic model ; Model ; Russia ; Soil ; Temperature ; Tundra
Construction d'un modèle dynamique du régime thermique des sols à partir d'un ensemble standard de données du Service hydrométéorologique. Une méthode pour calculer les paramètres thermophysiques du modèle avec des températures négatives des sols
est proposée. L'application du modèle aux sols de la toundra arctique a donné des résultats qui concordent bien avec les observations sur le terrain. La réponse du modèle à la variation des paramètres météorologiques d'entrée est étudiée.
Impacts of multiple-period lags in dynamic logit models
Bifurcation ; Choix ; Fonction d'utilité ; Interaction spatiale ; Modèle dynamique ; Modèle logit ; Stabilité structurale ; Système
Bifurcation ; Choice ; Dynamic model ; Logit model ; Spatial interaction ; Structural stability ; System ; Utility function
La sensibilité de la trajectoire d'un modèle logit dynamique (classe des modèles de choix discret) est étudiée dans le cadre d'une structure temporelle qui subit des retards périodiques. Les conséquences de divers types de structures sur le
comportement dynamique des modèles sont examinées (y compris les modèles d'interaction spatiale). L'instabilité tend à décroître à mesure que le nombre de retards s'accroît.
There is major interest in the development of ungauged flood forecasting models. This paper examines possible methods for improving the floodplain flow computation procedures. Specifically, the concepts of momentum exchange and multiple routing
Atmosphere ; Climatic variation ; Climatology ; Dynamic model ; Energy balance ; Evaporation ; Hydrology ; Hydrosphere ; Model ; Precipitation ; Stochastic model ; Thermal exchange ; Water cycle;Water circulation
The ways of incorporation of hydrologic cycle elements into the dynamic-stochastic heat and water exchange climate model are considered. Such approach enables to identify the main sources of precipitation climatologic variability.
Devon ; Earth surface processes ; England ; Floodplain ; Flow ; Fluvial hydrology ; Fluvial processes ; Model ; United Kingdom
A prototype two-dimensional finite element flow model for depth-averaged free surface flows is developed for floodplain environments. Preliminary model results indicate that this modelling approach can be used to identify dynamic variations
The relationship between catchment and hillslope properties implications of a catchment evolution model
Bassin-versant ; Erosion des sols ; Modèle ; Modèle mathématique ; Ruissellement ; Réseau de drainage
Catchment area;Watershed ; Drainage network ; Mathematical model ; Model ; Rill wash;Runoff ; Soil erosion
This paper will review a mathematical model that simulates the physical runoff and erosion processes that are believed to occur on hillslopes and channels of a typical catchment. More importantly, the model is able to explicitly model the growth
Catchment area;Watershed ; Costa Rica ; Dam ; Hydraulic works ; Mathematical model ; Model ; Sedimentation ; Suspended load ; Turbidity
Short summary of the theoretical considerations behind the model, a presentation of background data from the Cachí reservoir, and an application of the model on the Cachí reservoir. Thus the results are based on a theoretical model that is adapted
This paper assesses the utility of statistical models by examining methodological issues associated with empirical analysis of hydraulic and channel geometry relationships. It also describes and presents examples of advanced statistical models
Dynamic model ; Economic growth ; Economic structure ; Economic system ; Economy ; Input-output model ; Italy ; Matrix analysis
Présentation du modèle de Leontief. Conditions d'existence d'une stabilité relative d'un système économique donné : proposition de solutions correspondant à une croissance économique dite équilibrée. Application à l'économie italienne (1985) et aux
liaisons entre les différents secteurs économiques. Les propriétés structurales des matrices d'échanges intersectoriels mettent en évidence le comportement dynamique du modèle.
Flood ; Floodplain ; Fluvial processes ; Grain size distribution;Granulometry ; Model ; Numerical model ; Sedimentology ; Statistics ; United Kingdom ; Wales
to the Severn flood are used as input for a computer program of James' (1985) model. The pattern of sediment concentrations predicted by the model was compared with that obtained from statistical analysis of the flood sediment.
A numerical model for shore-normal sediment size variation on a macrotidal beach
Dynamique littorale ; Granulométrie ; Isle of Man ; Littoral ; Modèle ; Modèle numérique ; Royaume-Uni ; Zone intertidale
Coastal dynamics ; Coastal environment ; Grain size distribution;Granulometry ; Intertidal zone ; Isle of Man ; Model ; Numerical model ; United Kingdom
This paper describes a computer simulation model which is designed to predict the selective shore-normal sorting of grain sizes in the nearshore environment. The predicted grain size is used in an hydraulic interpretation of grain size distribution
of the intertidal profile, based on the hydrodynamic variations over a tidal cycle on a macrotidal beach. The model is successful in predicting the broad pattern of increasing grain size in the onshore direction which has been observed in nature.
Arizona ; Erosion ; Fluvial processes ; Fractal geometry ; Model ; Numerical model ; Topography ; United States
The A. develops a three-dimensional numerical model of fluvial landsculpting operative over large periods of time and large spatial scales. The model is based on simple approximations intended to capture the synoptic effects of fluvial processes
. Experiments with the model also offer tentative insight into how climatic and tectonic variables affect the evolqution of landscapes. The results of the model also relate to the complexity of natural landscape and its description through the language
Functional geomorphology. Landform analysis and models
Dynamique de versant ; Erosion des sols ; Modèle ; Mouvement de masse ; Pente de versant ; Splash ; Transport sédimentaire ; Versant
Mass movement ; Model ; Sediment transport ; Slope ; Slope dynamics ; Slope gradient ; Soil erosion ; Splash
An erosion limited slope evolution model is proposed as a generalisation for both flux (transport) limited and supply (weathering) limited conditions, which appear as extreme special cases. Distinctions can be made between rainsplash, rainflow
and rillwash, and there is scope for forecasting the evolution of an armour layer with grain size selectivity. The model has been implemented in finite difference form. Five model runs are shown as illustrations of the scope of the erosion limited approach.
The soil erodibility factor K used in the Revised Universal Soil Loss Equation can be calculated by two general applicable models. Data on the various soils covering northern Belgium are processed to evaluate the use of these models. Erodibility
factors are calculated for the top layer of soils where rill and interrill erosion occur. The K-values generated by each model are then compared throughout the range of soil types varying erodibility. For both models average K-values per unit area