@article { author = {Konagai, K. and Eskandari-Ghadi, M. and Noorzad, A.}, title = {Fundamental Steady state Solution for the Transversely Isotropic Half Space}, journal = {International Journal of Engineering}, volume = {16}, number = {2}, pages = {105-122}, year = {2003}, publisher = {Materials and Energy Research Center}, issn = {1025-2495}, eissn = {1735-9244}, doi = {}, abstract = {Response of a transversely isotropic 3-D half-space subjected to a surface time-harmonic excitation is presented in analytical form. The derivation of the fundamental solutions expressed in terms of displacements is based on the prefect series of displacement potential functions that have been obtained in the companion paper by the authors. First the governing equations are uncoupled in the cylindrical coordinates. Then, the uncoupled equations are analytically solved to obtain Green functions that are expressed in terms of Fourier series in the tangential direction of the coordinates and in terms of Hankel functions in its radial direction. The analytical Green functions of this paper are exactly same as the results of Lamb (1904) in the case of isotropic material. The Green functions can be used as the kernel functions of the boundary integral equation that is used to solve elastodynamic boundary value problems.}, keywords = {Transversely Isotropic,Elastodynamic Boundary Value Problem,Time Harmonic,Fundamental Solution (Green Function),potential function,Fourier series}, url = {https://www.ije.ir/article_71430.html}, eprint = {https://www.ije.ir/article_71430_c32ae4663fa112e9b7068c5daa5deab0.pdf} } @article { author = {Sharifzadeh, Mehdi and Ghodsi, M.}, title = {Parleda: a Library for Parallel Processing in Computational Geometry Applications}, journal = {International Journal of Engineering}, volume = {16}, number = {2}, pages = {123-132}, year = {2003}, publisher = {Materials and Energy Research Center}, issn = {1025-2495}, eissn = {1735-9244}, doi = {}, abstract = {ParLeda is a software library that provides the basic primitives needed for parallel implementation of computational geometry applications. It can also be used in implementing a parallel application that uses geometric data structures. The parallel model that we use is based on a new heterogeneous parallel model named HBSP, which is based on BSP and is introduced here. ParLeda uses two main libraries that are widely used: MPI for its message passing in the parallel environment and LEDA for its data structures and computations. Dynamic load balancing and replicating C++ objects are two key features of this library. This library was implemented after a survey in research on parallel computational geometry algorithms and selection of their common primitives.}, keywords = {Computational Geometry,Parallel Processing,Load Balancing,LEDA,MPI}, url = {https://www.ije.ir/article_71432.html}, eprint = {https://www.ije.ir/article_71432_7106beafbf45038c13dbdf7e0dcd2cfc.pdf} } @article { author = {Rzavi, F. and K. Karegar, H. and Askarian Abyaneh, H.}, title = {A New Approach for Determination of Break Points for Protection Co-Ordination}, journal = {International Journal of Engineering}, volume = {16}, number = {2}, pages = {133-142}, year = {2003}, publisher = {Materials and Energy Research Center}, issn = {1025-2495}, eissn = {1735-9244}, doi = {}, abstract = {Interconnected power system networks are multi loop structured. Settings determination of all over current and distance relays in such networks can be in different forms and complicated. The main problem is the determination of starting points i.e. the location of starting relays in the procedure for settings, which is referred to as break points. In this paper, a new approach based on graph theory is introduced in which the relevant matrices dimensions are much reduced. The method is flexible and achievement of the desired solution can be obtained in a relatively short time.}, keywords = {Break Point Set,Protection System,Relay Co,Ordination}, url = {https://www.ije.ir/article_71434.html}, eprint = {https://www.ije.ir/article_71434_070f1050fb93072e81d2ffb04ddb251d.pdf} } @article { author = {Alinejad, K. and Torkian, A.}, title = {Treatability Evaluation of Municipal Wastewater and Anaerobically-Treated Industrial Effluent in a Rotating Biological Contactor}, journal = {International Journal of Engineering}, volume = {16}, number = {2}, pages = {143-154}, year = {2003}, publisher = {Materials and Energy Research Center}, issn = {1025-2495}, eissn = {1735-9244}, doi = {}, abstract = {Performance of a rotating biological contactor (RBC) in treating municipal wastewater from primary sedimentation basin and anaerobically treated industrial effluent from an upflow anaerobic sludge blanket (UASB) reactor was investigated. The 280-L six-stage RBC pilot was operated at different organic loading rates and biodisc speeds. The overall removal efficiencies of soluble BOD decreased with increasing organic loading rates. Disk rotational speed did not have significant effect on performance in the range studied. The results showed that satisfactory treatment of UASB effluent to meet regulatory requirement for agricultural purposes (effluent BOD of 100 mg L-1) can be achieved with sufficient margin of safety at organic loading rate of up to 4.9±0.4 g SBOD m-2 d-1 with SBOD removal efficiency of 59±9%. For municipal wastewater, it was possible to achieve SBOD effluent values of below 20 mg L-1all the time. Most of the organics were removed in the first three stages with minimal contribution from the remaining stages of the RBC reactor. There was a decrease in SBOD removal efficiency to 74 ± 3% at OLR value of 17.8 ± 2.1 g SBOD m-2 d-1 and 66 ± 6% at OLR value of 4.7 ± 1.9 g SBOD m-2 d-1 for UASB effluent and municipal wastewater, respectively. The results for elimination capacity (EC) values indicated a linear relationship with first stage organic loading rates without any signs of limitation in the range of OLR values investigated in this study. However, average first-stage elimination capacity rates of 3.2 and 2 at OLR values of 17.8 and 11 gSBOD m-2 d-1 for UASB effluent and 1.3 and 2 at OLR values of 4.7 and 5.3 gSBOD m-2 d-1 for municipal wastewater were relatively lower than previous studies of RBC performance using domestic or industrial wastewater without anaerobic pretreatment. It was suggested that the lower EC values were due to the fact that a smaller fraction of UASB effluent was biodegradable as reflected in SBOD/SCOD ratios of 0.47± 0.04. For municipal wastewater, even though SBOD/SCOD ratios were 0.49± 0.03, the low EC values were suggested to be contributed to lower influent concentration potential considering first-order kinetics governing biochemical reactions.}, keywords = {RBC,Biofilm,Fixed,Film Treatment,UASB,Slaughterhouse,Industrial Wastewater}, url = {https://www.ije.ir/article_71436.html}, eprint = {https://www.ije.ir/article_71436_6f0d216e291a1cb5742beeea54d55e36.pdf} } @article { author = {Abbaspour-sani, K.}, title = {Sizing of a Packed Bed Storage for Solar Air Heating Systems (TECHNICAL NOTE)}, journal = {International Journal of Engineering}, volume = {16}, number = {2}, pages = {155-162}, year = {2003}, publisher = {Materials and Energy Research Center}, issn = {1025-2495}, eissn = {1735-9244}, doi = {}, abstract = {Packed bed units generally, represent the most suitable storage units for air heating solar systems. In these systems the storage unit receives the heat from the collector during the collection period and discharges the heat to the building at the retrieval process. A method for sizing of packedbed storage in an air heating system is represented. The design is based on the K-S curves, which have been generated for the storage used in the CSU solar House II through simulation. The complete simple solar heating system is simulated numerically during both the heating and retrieval processes. The simulation, which utilizes the hourly meteorological data, takes into account consideration of the principle parameters such as pressure drop across the bed, particle diameter, and mean voidage. The results are compared with the reported data from a real size of storage and also with the criteria of f-chart recommendation.}, keywords = {Packed Bed Storage,Air Heating Solar System,Simulation}, url = {https://www.ije.ir/article_71438.html}, eprint = {https://www.ije.ir/article_71438_72968027574dcc263707f8abd59af611.pdf} } @article { author = {Asgari, S.}, title = {Abnormal Plastic Behavior of Fine Grain Mp35n Alloy During Room Temperature Tensile Testing}, journal = {International Journal of Engineering}, volume = {16}, number = {2}, pages = {163-170}, year = {2003}, publisher = {Materials and Energy Research Center}, issn = {1025-2495}, eissn = {1735-9244}, doi = {}, abstract = {In this paper, results of an investigation on the strain hardening responses of superalloy MP35N with two average grain sizes of 38 and 1 μm, during room temperature tensile testing are reported. The microstructural evolution of the deformed samples was studied using optical and transmission electron microscopy (TEM) techniques. The strain hardening behavior of the 38 μm material was rather similar to that previously reported for low stacking fault energy FCC alloys. The plastic behavior of the fine-grained material, however, was unexpected. In the strain range of 0.1-0.4, the work hardening rate of the fine grain size sample was evidently lower than that of the large grain size material. Based on the TEM results obtained in this study, it is suggested that the unusual strain hardening response of MP35N alloy of 1 μm grain size is related to the difficulty of formation of deformation twins in these samples. Results obtained in this study further support the effectiveness of deformation twins in hindering crystallographic slip in low SFE FCC polycrystals and the need to develop new plasticity models to include the role of deformation twinning in these materials.}, keywords = {Strain hardening,Low SFE,MP35N,Deformation Twinning}, url = {https://www.ije.ir/article_71441.html}, eprint = {https://www.ije.ir/article_71441_67aa7b269807bb4555cba820d067477f.pdf} } @article { author = {Assempour, A. and Fathi, A.}, title = {Evaluation of Forming Severity and Thickness Variation in Deep Drawing Process}, journal = {International Journal of Engineering}, volume = {16}, number = {2}, pages = {171-182}, year = {2003}, publisher = {Materials and Energy Research Center}, issn = {1025-2495}, eissn = {1735-9244}, doi = {}, abstract = {This paper presents a new methodology for complete solution of general shape deep drawn parts. Evaluation of forming severity, estimation of the punch load and prediction of the thickness variation are the major results obtained in this work. The punch work is the summation of the homogenous work of flange deformation and bending and frictional works. To evaluate the strain energy of the flange, the so-called matrix method of slip line is used. To overcome the weakness of slip line field in prediction of the thickness variation, the so-called genetic algorithm has been adopted. In this procedure, the actual velocity field has been computed and used in energy formulation. The predicted thickness strain, punch load and forming severity have been compared with some published experimental results.}, keywords = {Deep drawing,Slip Line Field,Matrix method,Forming Severity,Bending Model,Genetic Algorithm}, url = {https://www.ije.ir/article_71443.html}, eprint = {https://www.ije.ir/article_71443_90686c2212f3b111ca1dd827def2f1c9.pdf} } @article { author = {Khoshravan-Azar, Esmaeil and Talati Kalasar, F.}, title = {An Experimental and Theoretical Study of Freezing of Pure Aluminum}, journal = {International Journal of Engineering}, volume = {16}, number = {2}, pages = {183-196}, year = {2003}, publisher = {Materials and Energy Research Center}, issn = {1025-2495}, eissn = {1735-9244}, doi = {}, abstract = {In this work, Boltzmann transform has been used to analyze the problem of freezing of pure Aluminum in semi-infinite domain. The uniqueness of solution (solidification front location) has been proved using the characteristics of the functions appeared in solution. The effect of density change on temperature distribution and errors resulting from ignoring this change have been investigated. The solidification problem in finite media was solved using the boundary element method (BEM), with quadratic shape functions. The applicability of the fundamental solution, as weighting function in BEM, in finite domain has been investigated. The accuracy of the method is illustrated through one-dimensional numerical examples. Some careful experiments were carried out, using the facilities of the School of Metallurgy and Materials at the University of Birmingham, UK, to obtain the data. Comparison of theoretical, numerical and experimental results revealed that good agreement exists between them. However, minor differences were observed due to imposing of the simplifying boundary conditions. The effects of density change may be ignored in small volumes, but they must be taken into account in real applications.}, keywords = {Phase change,Moving Boundary,interface,Gradient,Stefan Problem}, url = {https://www.ije.ir/article_71445.html}, eprint = {https://www.ije.ir/article_71445_2c5bfcd1f9d6cd9cd3a450a89af49387.pdf} } @article { author = {Alamdar Yazdi, A.}, title = {Effective Features of the Concentrated Loading Curves (Woven Fabric Objective Measurement)}, journal = {International Journal of Engineering}, volume = {16}, number = {2}, pages = {197-208}, year = {2003}, publisher = {Materials and Energy Research Center}, issn = {1025-2495}, eissn = {1735-9244}, doi = {}, abstract = {This paper deals with evaluation of the mechanical properties of woven fabrics. Method of evaluation is concentrated loading system. A total of 17 pieces of woven fabric is used. The most related parts of the curve to the properties are shown and as a result, effective features are lightened up.}, keywords = {Mechanical properties,Woven Fabrics,Concentrated Loading System,Effective Features,Low Stress}, url = {https://www.ije.ir/article_71447.html}, eprint = {https://www.ije.ir/article_71447_f1a69e18a1e639492f87059175a202d0.pdf} }