Bubble hydrodynamic influence on oxygen transfer rate at presence of cationic and anionic surfactants in electroflotation proces

In this work, the effects of the presence of surfactants in the liquid phase and the hydrodynamic regime of the bubble flow on the oxygen transfer rate were investigated in an electroflotation process in batch mode. The volumetric mass transfer coefficient KLα and the oxygenation capacity were evaluated to improve the performances of the electroflotation process in terms of oxygenation. In order to evaluate the liquid-side mass transfer coefficient KLα the volumetric mass transfer coefficient KLα was dissociated into KL and the specific interracial area （a） since the last one was obtained from the gas hold-up and the bubble diameter. The effect of Reynolds number which define the hydrodynamic of the bubble flow has been also studied. Models of KLa and KL have been established to show the effects of the hydrodynamic parameters and liquid phase characteristics on the oxygen transfer rate.     

Technical Efficiency Measures and Its Determinants for Olive Producing Farms in Tunisia: A Stochastic Frontier Analysis

Abstract: This paper investigates farm level technical efficiency of production and its determinants in a sample of 178 olive producing farms in Tunisia using a stochastic frontier production function approach applied to cross‐section data. Results indicate that technical efficiency of production in the sample of olive producing farms investigated ranges from a minimum of 58.5 per cent to a maximum of 95.5 per cent with an average technical efficiency estimate of 82 per cent. This suggests that olive producers may increase their production by as much as 18 per cent through more efficient use of production inputs. Further, the estimated coefficients in the technical inefficiency model indicate the positive effect on technical efficiency of the share of productive trees, the share of skilled labour and agricultural training. However, a negative relationship between technical efficiency and fruit trees is found.     

Bubble hydrodynamic influence on oxygen transfer rate at presence of cationic and anionic surfactants in electroflotation process

In this work, the effects of the presence of surfactants in the liquid phase and the hydrodynamic regime of the bubble flow on the oxygen transfer rate were investigated in an electroflotation process ...     

Environmental and Social Policy and Earning Persistence

In recent years, the effect of disclosure on environmental and social information has been the subject of much research in an Anglo‐Saxon context. The European field, and especially the French companies, have not been sufficiently discussed. In this paper, we investigate the relationship between social and environmental disclosure and earning persistence (as a proxy of earning quality). We use the content analysis method with annual reports as a measure of social and environmental disclosure; the empirical validation is applied to the companies listed in the SBF 250 French stock market index over the 2005–2010 period. To measure earning persistence we opt for a regression of a time‐series model on panel data. The findings show that French companies are characterized by a high level of social and environmental reporting; this situation may affect positively the quality of earnings such as more persistent earnings. This means that companies with a higher level of social and environmental commitment are more likely to take benefits and to communicate more persistent earnings and be desirable to investors. Copyright © 2012 John Wiley & Sons, Ltd and ERP Environment.     

Empirical Evidence of Productivity Growth in Tunisian Agriculture: 1961–2000

Abstract: This paper investigates the patterns of productivity growth in Tunisian agriculture during the period 1961–2000. Results indicate that output growth in Tunisian agriculture was high over the whole period of investigation. During the 1981–90 period, average output grew at an impressive rate exceeding 6 per cent. Over the whole period, capital was the most important contributor to output growth and labour was found to be the least significant contributor to economic growth. Total factor productivity contribution to output growth decreased from over 4 per cent in both the 1961–70 and 1981–90 periods to less than 3 per cent in both the 1971–80 and 1991–2000 periods. On average, productivity growth increased at an annual rate of 3.6 per cent.