The Experts below are selected from a list of 309 Experts worldwide ranked by ideXlab platform

Vangelis Tzouvelekas - One of the best experts on this subject based on the ideXlab platform.

  • measuring productivity growth under Factor non substitution an application to us steam electric power generation utilities
    European Journal of Operational Research, 2012
    Co-Authors: Margarita Genius, Spiro E. Stefanou, Vangelis Tzouvelekas
    Abstract:

    A theoretical framework is developed for decomposing Partial Factor productivity and measuring technical inefficiency when the underlying technology is characterized by Factor non-substitution. With Farrell’s (1957) radial index of technical inefficiency being inappropriate in this case, Russell non-radial indices are adapted to measure technical inefficiency in a Leontief-type model. A system of Factor demand equations with a regime specific technical inefficiency term is proposed and estimated allowing for dependence across inputs using a copula approach. Then the paper presents a complete decomposition of Partial Factor productivity changes using a dataset of US steam-power electric generation utilities.

  • Decomposing Partial Factor Productivity in the Presence of Input-Specific Technical Inefficiency: A Self-Dual Stochastic Production Frontier Approac
    Research Papers in Economics, 2007
    Co-Authors: Konstantinos Chatzimichael, Vangelis Tzouvelekas
    Abstract:

    The present paper provides a theoretical framework for the decomposition of Partial Factor productivity in the presence of input-specific technical inefficiency. Based on Kuroda’s dual approach and using the theoretical foundations developed by Kopp, we decompose the growth rate of Partial Factor productivity into five sources, namely, changes in input-specific technical efficiency, substitution effect, technical change, the effect of scale economies and a homotheticity and input biased technological effect. The empirical model is based on a generalized self-dual Cobb-Douglas stochastic production frontier and on the methodological approach for measuring orthogonal input-specific technical efficiency suggested by Reinhard, Lovell and Thijssen. The model is applied to a panel data set of 723 cereal farms in Greece observed during the 1994-2003 cropping period obtained from FADN. The empirical results suggest that the labor productivity of cereal farms has been increased by 2.89 per cent annually. Technical change was found to be the main source of labor productivity (70.4%), while changes in technical efficiency also contributed significantly over the period analyzed (34.7%). On the other hand, substitution effect was found to affect negatively the rate of labor productivity (-14.2%).

Spiro E. Stefanou - One of the best experts on this subject based on the ideXlab platform.

Margarita Genius - One of the best experts on this subject based on the ideXlab platform.

Konstantinos Chatzimichael - One of the best experts on this subject based on the ideXlab platform.

  • Decomposing Partial Factor Productivity in the Presence of Input-Specific Technical Inefficiency: A Self-Dual Stochastic Production Frontier Approac
    Research Papers in Economics, 2007
    Co-Authors: Konstantinos Chatzimichael, Vangelis Tzouvelekas
    Abstract:

    The present paper provides a theoretical framework for the decomposition of Partial Factor productivity in the presence of input-specific technical inefficiency. Based on Kuroda’s dual approach and using the theoretical foundations developed by Kopp, we decompose the growth rate of Partial Factor productivity into five sources, namely, changes in input-specific technical efficiency, substitution effect, technical change, the effect of scale economies and a homotheticity and input biased technological effect. The empirical model is based on a generalized self-dual Cobb-Douglas stochastic production frontier and on the methodological approach for measuring orthogonal input-specific technical efficiency suggested by Reinhard, Lovell and Thijssen. The model is applied to a panel data set of 723 cereal farms in Greece observed during the 1994-2003 cropping period obtained from FADN. The empirical results suggest that the labor productivity of cereal farms has been increased by 2.89 per cent annually. Technical change was found to be the main source of labor productivity (70.4%), while changes in technical efficiency also contributed significantly over the period analyzed (34.7%). On the other hand, substitution effect was found to affect negatively the rate of labor productivity (-14.2%).

  • Decomposing Partial Factor Productivity in the Presence of Input-Specific Technical Inefficiency: A Stochastic Production Frontier Approach
    2006
    Co-Authors: Konstantinos Chatzimichael
    Abstract:

    The present paper provides a new methodological approach for the decomposition of Partial Factor productivity in the presence of input-specific technical inefficiency. Based on Kuroda’s methodological approach and using the theoretical foundations developed by Kopp, we decompose the growth rate of Partial Factor productivity into four sources, namely, changes in input-specific technical efficiency, substitution effect, technical change and productivity effect. The empirical model is based on a generalized self-dual Cobb-Douglas stochastic production frontier and on the methodological approach for measuring non-radial input-specific technical efficiency suggested by Reinhard, Lovell and Thijssen. The model is applied to a cross-section data set of 723crop farms in Greece during the 1994-2003 period obtained from FADN. The empirical results suggest that the labor productivity of crop farms has been increased by 2.63 per cent annually. Technical change was found to be the main source of labour productivity (71.6%), while changes in technical efficiency also contributed significantly over the period analyzed (38.2%). On the other hand, substitution effect was found to affect negatively the rate of labour productivity (19.9%). Introduction The measurement of productivity growth and the identification of the Factors that affect it was always an aspect of great interest for the economists. Productivity growth is the key variable that can ensure a continuously economic growth with a relative low cost. This fact is even more evident in the agricultural sector, where production faces many limitations because of the inelastic supply of the primal Factors (labour, land). Given these limitations, changes in productivity growth seem to be the answer to the question how the world will be able to feed itself in the next decades, in the sense that high rates of Factor productivity growth in the agricultural sector is a necessary presupposition for a self-sufficient economy (Mergos and Karagiannis). Furthermore, the increase of income in the Western countries in combination with the increase of population requires, necessarily, a growth in agricultural production. Productivity

Bjørn Nilsen - One of the best experts on this subject based on the ideXlab platform.

  • Rock slope stability analysis according to Eurocode 7, discussion of some dilemmas with particular focus on limit equilibrium analysis
    Bulletin of Engineering Geology and the Environment, 2017
    Co-Authors: Bjørn Nilsen
    Abstract:

    In Europe, rock slope stability analysis and slope design have to be based on Eurocode 7, which is today the basic standard for geotechnical, including rock engineering, design. According to Eurocode 7, several principles for stability analysis may be applied, including empirical, limit equilibrium, numerical, and probabilistic. Very often, particularly for excavated slopes, the limit equilibrium method is used for stability analysis and design. One particularly significant consequence of the introduction of Eurocode 7 is that for limit equilibrium analysis according to the Eurocode, the traditional principle of calculating a Factor of safety cannot be used. Instead, the so-called Partial Factor principle is to be used. The intention of the Eurocodes seems to be that Reliability Based Design should be applied also in rock engineering. This is, however, not reflected by the guidelines and descriptions of the present (2004)-edition of Eurocode 7, and for this and several other reasons there is considerable confusion and uncertainty related to the use of Eurocode 7 for rock engineering analysis and design. This paper discusses this issue with particular focus on limit equilibrium analysis of rock slope stability. It is concluded that due to the uncertain and variable character of input parameters, the limit equilibrium approach has evident shortcomings for stability analysis of rock slopes, particularly when the Partial Factor principle is applied.

  • new trends in rock slope stability analyses
    Bulletin of Engineering Geology and the Environment, 2000
    Co-Authors: Bjørn Nilsen
    Abstract:

    The paper discusses alternative approaches to stability analyses including the traditional deterministic principle, the so-called Partial Factor principle and the probabilistic approach which assesses the probability of failure rather than the Factor of safety. To illustrate the different principles and approaches, stability analyses of road cuts near Trondheim, central Norway, are used as examples. It is concluded that although the traditional deterministic approach has the advantage of being well established and easy to understand, to conform with new standards and guidelines it is likely to be replaced by the Partial Factor principle. To obtain the best possible basis for evaluation it is useful to include a probabilistic analysis.