Modelistic interpretation of the power response of a polymer electrolyte fuel cell

It has been demonstrated recently that the power response of a polymer electrolyte fuel cell can be interpreted on the basis of a quadratic logistic differential equation. As this is a conceptual approach, the power response was obtained in this work from structural models in order to compare the results with the logistic equation. In this way it is possible to evaluate the contribution of the different effects that limit the response of the cell. It was found that the best comparison between the logistic equation and the structural model is obtained when the dependence of the membrane resistance with current density is considered.     

Limnology and culture-based fisheries in non-perennial reservoirs in Sri Lanka

This study was carried out to investigate the possibility of using the limnological characteristics of non‐perennial reservoirs in Sri Lanka for the future management of culture‐based fisheries. Forty‐five reservoirs were randomly selected to study their limnology, out of which 32 were stocked with fish fingerlings of Chinese and Indian carps, tilapia and freshwater prawn at stocking densities ranging from 218–4372 fingerlings ha^?1. Of these, 23 reservoirs were harvested at the end of the culture period (6–10 months). Thirteen limnological parameters were measured during the water retention period of each of the 45 reservoirs between November 2001 and January 2004. The mean values of the limnological parameters were used to ordinate the reservoirs through principal component analysis. Ordination showed a productivity gradient among reservoirs where Secchi disc depth, total phosphorus, chlorophyll‐a, inorganic turbidity and organic turbidity were identified as key factors. The total fish yield of culture‐based fisheries was positively correlated to the scores of the first principal component axis. This study reveals that it is possible to classify non‐perennial reservoirs in Sri Lanka based on the above limnological parameters in order to develop culture‐based fisheries and that they could be applicable in comparable water bodies elsewhere in the tropics.     

Moving boundary in non-equilibrium simple batch distillation in non-ideal systems

This work is concerned with the computational aspects of the dynamic behavior of a simple distillation process using the irreversible model. The composition trajectories in residue curve map diagrams were calculated for a methanol/isopropanol/water mixture. The composition paths calculated by the irreversible model were compared to published experimental results for this mixture. The simulation results showed that residue curves, including the simple distillation boundaries, were sensitive to the irreversible model applied. Furthermore, since simple distillation boundaries and residue curves had been constructed using the same model equilibrium and irreversible ones. Another phenomenon observed from the numerical results was the occurrence of binary azeotropes isopropanol–water in the non-ideal mixture analyzed.     

Cost profile prediction for grid computing

The accurate prediction of cost profiles of future job tasks on the nodes of clusters or grids helps users to select the cost performance profile that best suits their budgets. The current software designed to deploy job tasks uses forecasts of the target computers' future load profiles. Once the job task's future load profile is known, converting it to its cost profile needs further analysis as the cost depends on other factors such as its delays and variable background loads. This paper introduces a new charging mechanism for charging future job tasks, called the Cost Profiling Model. The model has been implemented in a Software Framework and evaluated for its prediction accuracy. Copyright © 2009 John Wiley & Sons, Ltd.     

Evaluation of the impact of access to electricity: A comparative analysis of South Africa,China, India and Brazil

Most developing countries include rural electrification programs in their efforts to improve social conditions. There are, however, several obstacles to the evaluation of such programs and therefore of their social, economic, environmental and energy impacts on the target population, particularly on impoverished communities located in remote areas. Evaluation of the efficacy of public policies aimed at rural electrification in South Africa, China, India and Brazil enables such actions to be quantified and re-considered so as to bolster the sustainability of their planning and implementation and also so as to enable comprehension of the significance of access to electricity in relation to other aspects of the drive to improve living standards. The provision of electric energy amounts to more than access to a public service and should be considered an essential right, in a context of social equity and justice, which permits social integration and the access to other equally essential services.     

Standardisation of the sour cassava starch reduces the processing time by fermentation water monitoring

This work investigated the pH, titratable acidity and total solids of the cassava starch fermentation water, using the traditional method and a method modified through the addition of glucose. Sour cassava starch production controlled by the characteristic of the fermentation water produced the best product (biscuit specific volume of 7.66 ± 0.41 mL g^?1) at 33th day of fermentation in the modified method and at 85th day (biscuit specific volume of 6.53 ± 0.59 mL g^?1) in traditional method. But, comparatively to the commercial sour cassava starch (biscuit specific volume of 3.48 ± 0.12 mL g^?1), both traditional and modified methods, controlled by titratable acidity of fermentation water, can be retired from the fermentation tank in the 19th and 32th day of fermentation, with biscuit specific volume of 4.75 ± 0.30 and 5.17 ± 0.46 mL g^?1, respectively. Determining fermentation time can help to standardise sour cassava starch and to promote future applications of the fermentation water as a raw material.     

Preparation of a spread from shrimp by-catch fish

The composition of shrimp by-catch fish from the Central-Western region of Venezuela at different periods of the year was studied, as well as mean size and weight of same, and the yields obtained during processing, until the edible portion (pulp) was reached. The pulp was also analyzed from the physical, chemical and microbiological (pH, basic volatile N, trimethylamine, thiobarbituric acid test, moisture, fat, protein, ashes content and mesophyll and psychrophilic counts) points of view. The purpose of these studies was to determine its quality and freshness, since said pulp was utilized for the preparation of a canned and sterilized bread spread. Results obtained indicated the pulp to have an acceptable freshness, a fact which reflected in a final product with adequate characteristics. The bread spread was also analyzed from the physical, chemical, microbiological and sensory viewpoints (objective analyses of color and texture, pH, rancidity and sterility tests, moisture, fat protein, ashes, carbohydrates, sodium chloride contents, and sensory evaluation). In addition, these analyses were repeated monthly during the three-month storage period at two temperatures. On the basis of the above-mentioned findings, it was possible to determine that the bread spread had adequate acceptability and stability during storage. Furthermore, raw material variations did not affect the final product characteristics, which resulted in a product with commercial potential.     

Ionizing Radiation Induced Effects on Cephradine. Influence of Sample Moisture content, Irradiation Dose and Storage conditions

The effects of gamma and electron beam irradiation on cephradine were studied as a function of dose. In particular, degradation products and free radicals induced by radiation on samples with different moisture content were investigated. The influence of daylight on the kinetics of the degradation processes was also evaluated.