Materials and Energy Research CenterInternational Journal of Engineering1025-249510319970801The Mechanism of Chromium Biosorption by Saccharomyces Cerevisiae12112671180ENM.VossoughiChemical and Petroleum Engineering, Sharif University of TechnologyIranAlemzadehChemical Engineering, Sharif University of TechnologyJournal Article19700101The Biosorption property of S. cerevisiae for chromium uptake was investigated in an immobilized cell bioreactor. Saw dust was utilized as the solid bed in the reactor. Adsorption of S. cerevisiae on saw dust obeys a first order reaction kinetic up to 6 hours. The immobilized biomass particles are porous and exist in the new generation of biological adsorbent. Chromium biosorption was studied in this bioreactor. The maximum uptake capacity of the heavy metal is a function of the initial chromium concentration. Chromium biosorption obeys a Freundlich isotherm kinetic model.https://www.ije.ir/article_71180_39c2558c27e726b2457c596a8ff9c646.pdfMaterials and Energy Research CenterInternational Journal of Engineering1025-249510319970801Shape Effects and Definition of Hydraulic Radius in Manning \'s Equation in Open Channel Flow12714271181ENM.MohammadiCivil Engineering, Urmia UniversityJournal Article19700101In the Manning equation the hydraulic radius can be defined as the cross-section dimension of the shape. In pipe flow the bed shear stress is assumed to be uniformly distributed along the wetted perimeter which cannot be true in open channel flow. Hence, three approximation of the true boundary shear-stress distribution are examined and more practical conveyance depth or resistance radius formulae are developed in three case to substitute for the hydraulic radius. In this study, special emphasis is placed on a particular channel cross-section including rectangular and triangular sections. Based on the logarithmic velocity profile a formula for a normal depth of this particular channel section is also developed it is shown that the shear stress distribution may be calculated with sufficient accuracy by simpler approximation methods. Finally, a presentation is made of a numerical e ample comparing the proposed formulae to the classic hydraulic radius concept.https://www.ije.ir/article_71181_976a00b5caacb2c8b8f6d528218295e8.pdfMaterials and Energy Research CenterInternational Journal of Engineering1025-249510319970801A New Algorithm for the Deinterleaving of Radar Pulses14315271182ENH. R.Bakhshi, Tarbiat Modarres UniversityE.KabirElectrical and computer Engineering, Tarbiat Modarres UniversityJournal Article19700101This paper presents a new algorithm for the deinterleaving of radar signals, based on the direction of arrival (DOA), carrier frequency (RF), and time of arrival (TOA). The algorithm is applied to classic (constant), jitter, staggered, and dwell switch pulse repetition interval (PRI) signals. This algorithm consists of two stages. In the first stage, a Kohonen neural network clusters the received pulses on the basis of frequency and DOA. In this stage radars having the same frequency and DOA, are identified as one class. In the second stage, the number of existing emitters and their PRIs is determined by using TOA information. The algorithm for the deinterleaving uses the information obtained from the previous analysis to reduce the required computation time. The simulation results show that the algorithm is successful in high pulse density environments and for the complex signal types.https://www.ije.ir/article_71182_d7008c73f350d7fe8723313b7e44b9d7.pdfMaterials and Energy Research CenterInternational Journal of Engineering1025-249510319970801Bus Assignment to Iranian Pilgrims During Pilgrimage15316271183ENB.KarimiIndustrial Engineering, Amirkabir University of TechnologyM.B.AryanezhadIndustrial Engineering, Iran University of Science and Technology (IUST)Journal Article19700101Among the multitude of activities of Hajj Organization which require careful planning bus assignment to the Iranian pilgrim caravans d g pilgrimage is the most important one. The objective of this assignment is to have a minimum number o standing passengers/empty seats, while satisfying a large number of operational and religious constrain. This problem was formulated as a large scale zero-one programming model which had to be solved heuristically. In this paper, the special nature of the problem was exploited which allowed it to be reformulated as a Linear Programming model. Computational experience with the actual data shows the success of this new approach.https://www.ije.ir/article_71183_9c566eda2ca8b61a7f3ce5a1c51539a7.pdfMaterials and Energy Research CenterInternational Journal of Engineering1025-249510319970801A Numerical Study of Natural Convection and Radiation Interaction in Vertical Circular Pin16317271184ENG.SoleimaniMechanical Engineering, University of TabrizEsmaeilKhoshravan-AzarMechanical Engineering, University of TabrizJournal Article19700101A numerical finite difference study has been earned out for two dimensional radiation-natural convection interaction phenomena in a vertical circular pin located at a non-participating (i.e. transparent) fluid. The coupled conservation equations in boundary layer (continuity, momentum, and energy equations) and pin energy equation are solved simultaneously using modified box method and fully implicit finite difference scheme. The effect of three major parameters on pin temperature distribution, velocity and temperature profile at boundary layer, local heat transfer coefficient, and local heat flux are examined in detail. These parameters are radiation-conduction parameter. Also the surface heat transfer coefficient increases with increasing radiative interaction.https://www.ije.ir/article_71184_4dc2597fc56b5ce186ccb8952c0edc91.pdfMaterials and Energy Research CenterInternational Journal of Engineering1025-249510319970801Beneflciation Studies of Bama Oxidized Lead and Zinc Ore17318071185ENA.AbdoulzadehMining Engineering, Sharif University of TechnologyM.Oliazade, Sharif University of TechnologyJournal Article19700101Bama is one of the major concentrating plant in Iran which treats nearly 1500 tons per day sulphidic lead and zinc ore. Large amount of oxidized ore exist in Bama which has been extracted along with sulphidic ore. The main objective of the present investigation was the up-grading of the ore from Goshfil which is the major deposit in Bama. The ore contained about 16% zinc as smithsonite, about 1.5% lead as cerussite and about 34.5% iron oxide. Mineralogical studies showed that most zinc and lead minerals could be liberated if the ore ground to minus 75 microns. Pre-concentration methods, such as gravity and magnetic separations, were examined to remove gangue minerals, mainly calcite, dolomite and hematite. The results obtained were not promising. Rotation was extensively applied. Due to low amount of lead in the sample, flotation was not able to concentrate lead minerals. More efforts were made to float zinc minerals. Various cationic and anionic collectors were examined, while it was tried to optimize flotation variables such as pH, collector dosage in each case. At best conditions, the grade of zinc increased to 34.6% with 50.9% recovery and 34.0% with 6 1.5% recovery using amines and fatty acids respectively.https://www.ije.ir/article_71185_39c2558c27e726b2457c596a8ff9c646.pdf