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Safari E.,Queens University | Jalili Ghazizade M.,University of Tehran | Shokouh A.,Amirkabir Technical University | Nabi Bidhendi Gh.R.,University of Tehran
International Journal of Environmental Research

High strength fresh leachates generated at a new disposal trench, compost plant and partially stabilized leachate of an older trench were characterized in terms of anaerobic degradation at laboratory batch scale at 35 °C. Fresh leachate had extremely high COD of 66,710 - 89,501 mg/L along with low pH of 4.1 -5.9 in contrast to older and therefore partially stabilized leachate with a COD of about 19,000 mg/L and higher pH of 8.4. Filtration of fresh leachate samples showed to have considerable effect on continuation of degradation as for the unfiltered samples, degradation nearly stopped after a slight reduction in COD. As a first attempt, it was shown that a considerably better fit was achieved for COD variations of filtered fresh leachate samples using first order multistage kinetic model based on which hydrolysis was found to have the smallest rate, therefore being the rate limiting stage in anaerobic degradation process. Source

Shojafar M.,University of Rome La Sapienza | Pooranian Z.,Islamic Azad University at Dezful | Meybodi M.R.,Amirkabir Technical University | Singhal M.,University of California at Merced
Journal of Intelligent Manufacturing

Cost and execution time are important issues in economic grids, which are widely used for parallel computing. This paper proposes ALATO, an intelligent algorithm based on learning automata and adaptive stochastic Petri nets (ASPNs) that optimizes the execution time for tasks in economic grids. ASPNs are based on learning automata that predict their next state based on current information and the previous state and use feedback from the environment to update their state. The environmental reactions are extremely helpful for teaching Petri nets in dynamic environments. We use SPNP software to model ASPNs and evaluate execution time and costs for 200 tasks with different parameters based on World Wide Grid standard resources. ALATO performs better than all other heuristic methods in reducing execution time for these tasks. © 2013, Springer Science+Business Media New York. Source

Salek N.,Amirkabir Technical University | Jamre M.,Amirkabir Technical University | Moghaddam B. L.,Nuclear Science and Technology Research Institute, Iran | Jalilian A.R.,Nuclear Science and Technology Research Institute, Iran | Shamsaee M.,Amirkabir Technical University
Annals of Nuclear Energy

This manuscript describes an investigation on the production of 191Os/ 191mIr by Tehran Research Reactor (TRR). 191Os-hexachloro-osmate was obtained by thermal neutron (4 × 10 13 cm -2 s -1) irradiation of enriched 190Os sample followed by fusion with KOH and KNO 3 in acidic media. One of the important radionuclide impurities is 192Ir that is produced during irradiation in reactor. Separation this impurity from 191Os is developed by a new approach in this research and the total recovery yield of 191Os is about 99% and the total time required for completion the procedure is about 30 min. This method improved the yield and the time of performance in comparison with values published in literature. 191Os is loaded on an anion-exchange column and 191mIr eluted with normal saline. Each elution is 1 ml of 0.9% saline at pH 6.5-7. The yield of generator was assessed for 2 weeks. 191mIr yield is 15-18% and 191Os breakthrough is about 2 × 10 -4-2 × 10 -3. © 2011 Elsevier Ltd. All rights reserved. Source

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