Search results for "simulation model"

Wastewater Reuse Effects on Soil Hydraulic Conductivity

2004

The wastewater total suspended solids (TSS) concentration effects on the saturated hydraulic conductivity, \iK\ds, of a clay and a loam soil were investigated on laboratory repacked soil cores by a constant head permeameter. Both municipal wastewater (MW) and artificial wastewater (AW) with different TSS concentrations were used, with the aim to evaluate, by comparison, the effects of biological activity. The development of a surface sealed layer was investigated in loam soil columns supplied with AW and equipped with water manometers at different depths to detect the hydraulic head gradient changes. In the loam soil, \iK\ds reduced to about 80% of the initial value after infiltration of 17…

Understanding the shortcomings of commodity-based technology in input-output models: an economic-circuit approach

2004

International audience; The Make-Use Model serves as a basis for most national accounting systems as the System of National Accounts (SNA) and is acknowledged as the most suitable model for interregional analysis. Two hypotheses are traditionally made featuring either industry-based technologies (IBT) or commodity-based technologies (CBT). While industry-based technologies can be easily interpreted in terms of a demand-driven economic circuit, it will be shown that: (1) commodity-based technologies cannot be interpreted as a demand-driven economic circuit because this involves computing the inverse of a matrix (the matrix of industry output proportions), which is either impossible or genera…

Using Hydrus 2-D Simulation model to evaluate wetted soil volume in subsurface drip irrigation systems.

2007

Drip irrigation is considered one of the most efficient irrigation systems. Alternatively to the traditional drip irrigation systems, laterals can be installed below the soil surface. Realizing the subsurface drip irrigation (SDI), which recently has been increasing in use as a consequence of advances in plastics technology, making SDI equipment more affordable and long lasting. Due to its potential high efficiency SDI may produce benefits, especially in places where water is a limited source. As the use of SDI is relatively new, a better understanding of the infiltration process around a buried point source can contribute to increased water use efficiency and consequently the success of dr…

Biproportional Methods And Interindustry Dynamics: The Case of Energy in France

1996

Dynamique de la structure industrielle française

1990

A Note on added information in the RAS Procedure: reexamination of some evidence

2006

International audience; An example in Miernyk (1977) presented a rather counterintuitive result, namely that introducing accurate exogenous information into an RAS matrix estimating procedure could lead to an estimate that was worse than one generated by RAS using no exogenous information at all. This became an oft-cited black mark against RAS. Miller and Blair (1985) included a different (and small) illustration of the same possibility. It was recently pointed out by one of us that the Miller/Blair numerical results are wrong. For that reason, we decided to reexamine all the empirical evidence we could find on the subject. While figures in both Miernyk and Miller/Blair appear to be wrong, …

Regional Multicriteria Analysis and Influence Relation

1986

Note about the concept of ‘Net Multipliers'

2002

International audience; Net multipliers, as introduced by Oosterhaven and Stelder (2002) accept outputs as entries instead of final demand. They are found by multiplying ordinary multipliers by the final demand ratio over the sector's output. This pragmatic solution suffers from ratio instability over time. The alternative net multipliers proposed here are based on the interpretation of the Leontief inverse matrix for the effects generated at each round. The new solution is not sensitive to the size of impacts. Now net multiplier is equal to the corresponding ordinary multiplier minus one, and the ordering of multipliers is unchanged.

On Boolean topological methods of structural analysis

2001

The properties of Boolean methods of structural analysis are used to analyze the intern structure of linear or non linear models. Here they are studied on the particular example of qualitative methods of input-output analysis. First, it is shown that these methods generate informational problems like biases when working in money terms instead of percentages, losses of information, increasing of computation time, and so on. Second, considering three ways to do structural analysis, analysis from the inverse matrix, from the direct matrix and from layers (intermediate flow matrices), these methods induce topological problems; the adjacency of the adjacency cannot be defined from the inverse ma…

Biproportion et offre dominante (A propos de l'article d'André Torre ‘Sur la signification théorique du modèle d'offre multisectoriel')

1996

One replies here to partisans of the reject of the supply-driven model in input-output analysis and especially to A. Torre (Revue Economique, 5, 44, 951-970). First of all, demand-driven hypothesis (Leontief) and supply-driven hypothesis (Ghosh) are symmetrical and incompatible, what forbidden to reject the second to the motive that it depends on the first. Secondly, the results earlier obtained for France of 1970 to 1985 from the method of the biproportionnal filter show that there is so much instability in the long term in the columns than in the rows of the flow matrix. Thirdly, the assimilation of the usage of allocation coefficients to the adoption of the supply-side model is excessive.