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Purpose A study was conducted to characterize the 'Madhyam culture' (Excel Crop Care Limited.), an aerobic-composting microbial consortium culture, and understand composting dynamics, product quality and use in crop production vis-à-vis vermi-composting (using earthworms). Methods 16S rDNA analysis was used to characterize aerobic-composting culture. Aerobic-composting and vermi-composting technologies were evaluated to decompose sorghum straw and dung biomass (80:20 ratio; primed with 0.5% urea and 4% rock phosphate) to study days to maturity and composting dynamics in terms of changes in temperature and microbial population. Compost quality was tested for macro-, micro-nutrients and C:N ratio, and evaluated for food production in on-farm trials. Results 16S rDNA analysis screened sixteen bacterial isolates-eight related to genus Bacillus, three to each Halobacillus and Staphylococcus, one to each Microbacterium and Streptomyces. The population of bacteria was 4.5 cfu ml −1 at 10 −7dilution. Aerobic-and vermi-composts matured in around 50 and 60 days, respectively. Aerobic-composting throughout recorded relatively higher bacterial population, and higher temperatures during the initial phase. Aerobic-compost tested for high nutrient (1.55% N, 0.93% P, 1.00% K) content and stable C:N ratio (10.3) compared to vermi-compost (1.11% N, 0.43% P, 0.96% K and C:N ratio of 11.7). Field evaluation of both composts showed yield benefit and saving of chemical fertilizers up to 25%. Conclusions Aerobic-composting (using microbial consortium culture), like vermi-composting, proved to be an effective technology with advantage of no requirement to maintain ambient living conditions in lean periods as is required for earthworms in vermi-composting, but needs more energy/labor for biomass turnings.

Because of environmental problems, it becomes necessary to develop alternative fuels that give engine performance at par with diesel. Among the alternative fuels, biodiesel and its blends hold good promises as an eco-friendly and the most promising alternative fuel for Diesel engine. The properties of biodiesel and its blends are found similar to that of diesel. Many researchers have experimentally evaluated the performance characteristics of conventional Diesel engines fueled by biodiesel and its blends. However, experiments require enormous effort, money and time. Hence, via finite-time thermodynamics simulation, an air-standard Diesel cycle model with heat transfer loss and variable specific heats of working fluid is analyzed to predict the performance of Diesel engine. The effect of compression ratio, cut-off ratio and fuel type on output work and thermal efficiency is investigated through the model. The fuels considered for the analysis are conventional diesel, rapeseed oil biodiesel and its blend (20 % biodiesel and 80 % diesel by volume). Numerical simulations showed that the output work and thermal efficiency of the engine decrease with increase of cut-off ratio for all fuels. Also, the model predicts similar performance with diesel and biodiesel blend which means that the biodiesel blend (20 % biodiesel and 80 % diesel by volume) could be a good alternative and eco-friendly fuel for conventional Diesel engines without any need to modify the engine.

This study is concerned with the performance analysis and comparison of air standard Diesel and Diesel-Atkinson cycles with heat-transfer loss, friction like term loss and variable specific-heat ratio of the working fluid based on finite-time thermodynamics. Also numerical examples are detailed to show the relations between the output power and the compression ratio, between the thermal efficiency and the compression ratio, as well as the optimal relation between the output power and the thermal efficiency of both cycles. Furthermore, the effects of variable specific-heat ratio of the working fluid, heat transfer and the friction-like term loss on the performance of both irreversible cycles are analyzed. Comparison of the performance of cycles shows that the heat efficiency and the output power of an air standard Diesel-Atkinson are higher than the Diesel ones and the points of maximum output power and thermal efficiency of Diesel-Atkinson cycle occur at the lower compression ratio. Reduction of Noxis another advantage of Diesel-Atkinson cycle. The results obtained in this paper provide guidance for the design of Diesel and Diesel-Atkinson engines.