eng
Materials and Energy Research Center
International Journal of Engineering
1025-2495
1735-9244
2003-07-01
16
2
105
122
71430
Fundamental Steady state Solution for the Transversely Isotropic Half Space
K. Konagai
konagai@iis.u-tokyo.ac.jp
1
M. Eskandari-Ghadi
ghadi@colorado.edu
2
A. Noorzad
soilporous@yahoo.com
3
, University of Tokyo
, University of Mazandaran
, Sharif University of Technology
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.
https://www.ije.ir/article_71430_c32ae4663fa112e9b7068c5daa5deab0.pdf
Transversely Isotropic
Elastodynamic Boundary Value Problem
Time Harmonic
Fundamental Solution (Green Function)
potential function
Fourier series
eng
Materials and Energy Research Center
International Journal of Engineering
1025-2495
1735-9244
2003-07-01
16
2
123
132
71432
Parleda: a Library for Parallel Processing in Computational Geometry Applications
Mehdi Sharifzadeh
shzadeh@yahoo.com
1
M. Ghodsi
ghodsi@sharif.edu
2
Computer Engineering, Sharif University of Technology
Computer Engineering, Sharif University of Technology
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.
https://www.ije.ir/article_71432_7106beafbf45038c13dbdf7e0dcd2cfc.pdf
Computational Geometry
Parallel Processing
Load Balancing
LEDA
MPI
eng
Materials and Energy Research Center
International Journal of Engineering
1025-2495
1735-9244
2003-07-01
16
2
133
142
71434
A New Approach for Determination of Break Points for Protection Co-Ordination
F. Rzavi
hasnomail@ije.ir
1
H. K. Karegar
h_kazemi_ir@yahoo.com
2
H. Askarian Abyaneh
askarian@cic.aut.ac.ir
3
, Amirkabir University of Technology
Electerical Engineering, Amirkabir University of Technology
Electerical Engineering, Amirkabir University of Technology
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.
https://www.ije.ir/article_71434_070f1050fb93072e81d2ffb04ddb251d.pdf
Break Point Set
Protection System
Relay Co
Ordination
eng
Materials and Energy Research Center
International Journal of Engineering
1025-2495
1735-9244
2003-07-01
16
2
143
154
71436
Treatability Evaluation of Municipal Wastewater and Anaerobically-Treated Industrial Effluent in a Rotating Biological Contactor
K. Alinejad
hasnomail@ije.ir
1
A. Torkian
torkian@sharif.edu
2
Werc Engineering, Sharif University of Technology
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.
https://www.ije.ir/article_71436_6f0d216e291a1cb5742beeea54d55e36.pdf
RBC
Biofilm
Fixed
Film Treatment
UASB
Slaughterhouse
Industrial Wastewater
eng
Materials and Energy Research Center
International Journal of Engineering
1025-2495
1735-9244
2003-07-01
16
2
155
162
71438
Sizing of a Packed Bed Storage for Solar Air Heating Systems (TECHNICAL NOTE)
K. Abbaspour-sani
k-abaspour@merc.ac.ir
1
Solar Energy Research Group, Department of Energy, Merc
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.
https://www.ije.ir/article_71438_72968027574dcc263707f8abd59af611.pdf
Packed Bed Storage
Air Heating Solar System
Simulation
eng
Materials and Energy Research Center
International Journal of Engineering
1025-2495
1735-9244
2003-07-01
16
2
163
170
71441
Abnormal Plastic Behavior of Fine Grain Mp35n Alloy During Room Temperature Tensile Testing
S. Asgari
sasgari@sharif.edu
1
Materials Engineering, Sharif University of Technology
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.
https://www.ije.ir/article_71441_67aa7b269807bb4555cba820d067477f.pdf
Strain hardening
Low SFE
MP35N
Deformation Twinning
eng
Materials and Energy Research Center
International Journal of Engineering
1025-2495
1735-9244
2003-07-01
16
2
171
182
71443
Evaluation of Forming Severity and Thickness Variation in Deep Drawing Process
A. Assempour
assem@sharif.edu
1
A. Fathi
hasnomail@ije.ir
2
Mechanical Engineering, Sharif University of Technology
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.
https://www.ije.ir/article_71443_90686c2212f3b111ca1dd827def2f1c9.pdf
Deep drawing
Slip Line Field
Matrix method
Forming Severity
Bending Model
Genetic Algorithm
eng
Materials and Energy Research Center
International Journal of Engineering
1025-2495
1735-9244
2003-07-01
16
2
183
196
71445
An Experimental and Theoretical Study of Freezing of Pure Aluminum
Esmaeil Khoshravan-Azar
ekhosh@tabrizu.ac.ir
1
F. Talati Kalasar
hasnomail@ije.ir
2
Mechanical Engineering, University of Tabriz
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.
https://www.ije.ir/article_71445_2c5bfcd1f9d6cd9cd3a450a89af49387.pdf
Phase change
Moving Boundary
interface
Gradient
Stefan Problem
eng
Materials and Energy Research Center
International Journal of Engineering
1025-2495
1735-9244
2003-07-01
16
2
197
208
71447
Effective Features of the Concentrated Loading Curves (Woven Fabric Objective Measurement)
A. Alamdar Yazdi
aalamdar@yazduni.net
1
Textile Engineering, Yazd University
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.
https://www.ije.ir/article_71447_f1a69e18a1e639492f87059175a202d0.pdf
Mechanical properties
Woven Fabrics
Concentrated Loading System
Effective Features
Low Stress