Materials and Energy Research Center
International Journal of Engineering
1025-2495
22
2
2009
06
01
Numerical Modeling and Simulation of Highly Preheated and Diluted Air Combustion Furnaces
107
118
71768
EN
M.
Rahimi
Chemical & Petroleum Engineering, Razi university
A.A.
Hamidi
Chemical & Petroleum Engineering, University of Tehran
K.
Abbasi Khazaei
Graduate School of the Environment & Energy, Science and Research Campus, Islamic Azad Universi
Journal Article
1970
01
01
This paper presents some of the results of the modeling and simulation of an industrial furnace under the conventional combustion as well as under the highly preheated and diluted air combustion (HPDAC) conditions. The results are obtained using a computer program written by authors in FORTRAN language. It was found that, the HPDAC offers a more uniform and relatively moderate gas temperature profile resulting in the reduction of NOx pollutant formation and also a larger flame indicating lower maximum local heat release rate. Higher thermal performance (up to 39%) and therefore lower fuel or energy consumption up to (30%) which result in reduction of CO2 pollutant emission to the environment, in addition to requiring a smaller chamber size for processing the same material/feed or increasing productivity for the same furnace size are also concluded. Finally, in this paper a modified concept and formula has been proposed and used to define the chemical flame shape and size.
http://www.ije.ir/article_71768_f972dd26913bb39c52e009feafd89327.pdf
Materials and Energy Research Center
International Journal of Engineering
1025-2495
22
2
2009
06
01
A Computational Approach to the Flow of Walter’s Liquid B′ through Annulus of Coaxial Porous Circular Cylinders for High Suction Parameter (RESEARCH NOTE)
119
124
71771
EN
Anjali
Pant
Mathematics, GPCN
Krishna Kumar
Singh
Civil Engineering, National Institute of Technology Kurukhshetra
Journal Article
1970
01
01
The present investigation studies the behavior of steady flow of visco-elastic liquid between two porous coaxial circular cylinders, where both the cylinders are rotating with different uniform angular velocities about the common axis. In addition, the inner cylinder has uniform velocity along the axis and the visco-elastic fluid, which is a Walters liquid B′, is allowed to flow in the annulus. The investigation deals with high order suction parameter. The problem is to be used in the chemical industry. Higher Reynolds numbers, visco-elastic parameters and suction parameter have also been considered in the study. A numerical approach has been used to demonstrate out the results and present them graphically.
http://www.ije.ir/article_71771_7490bf303f7c6d8f00578641dcc443eb.pdf
Materials and Energy Research Center
International Journal of Engineering
1025-2495
22
2
2009
06
01
Oscillatory MHD Flow of Blood through an Artery with Mild Stenosis (RESEARCH NOTE)
125
130
71773
EN
Dinesh
Kumar
Department of Mechanical & Industrial Engineering, Indian Institute of Technology, Roorkee
Sanjeev
Kumar
Mathematics, IBS, Khnadari, Agra
Sanjeet
Kumar
Mathematics, Lakshmi Narain College of Technology
Journal Article
1970
01
01
The purpose of this work is to study the effect of oscillatory MHD blood flow in stenosed artery. The analytical and numerical results are obtained for oscillatory MHD blood flow, which is assumed to be a Newtonian fluid. It was also assumed that the surface roughness is of cosine shaped and the maximum height of roughness is negligible, compared with the radius of un-constricted tube. The fluid mechanics of MHD blood flow in a stenosed artery is studied through a mathematical analysis, and the impact of magnetic effect on the instantaneous flow rate is discussed, which reduces, if we increase the Hartman number.
http://www.ije.ir/article_71773_c5449bd5fc1b4e8fc80b4c459b50bc19.pdf
Materials and Energy Research Center
International Journal of Engineering
1025-2495
22
2
2009
06
01
Numerical Modeling of Railway Track Supporting System using Finite-Infinite and Thin Layer Elements
131
144
71774
EN
Parviz
Moradi Pour
Department of Civil Engineering, Universiti Putra Malaysia
W.F
Yeat
Civil Engineering, University Putra Malaysia
W.A.M
Thanoon
Civil Engineering, University Putra Malaysia
J.
Noorzaie
Civil Engineering, university putra Malaysia
M.S.
Jaafar
Department of Civil Engineering, university putra Malaysia
Journal Article
1970
01
01
The present contribution deals with the numerical modeling of railway track-supporting systems-using coupled finite-infinite elements-to represent the near and distant field stress distribution, and also employing a thin layer interface element to account for the interfacial behavior between sleepers and ballast. To simulate the relative debonding, slipping and crushing at the contact area between sleepers and ballast, a modified Mohr-Coulomb criterion was adopted. Further more an attempt was made to consider the elasto plastic materials’ non-linearity of the railway track supporting media by employing different constitutive models to represent steel, concrete and other supporting materials. It is seen that during an incremental-iterative mode of load application, the yielding initially started from the edge of the sleepers and then flowed vertically downwards and spread towards the center of the railway supporting system.
http://www.ije.ir/article_71774_185c107c13972ddadd956ca99aea4c36.pdf
Materials and Energy Research Center
International Journal of Engineering
1025-2495
22
2
2009
06
01
Handwritten Character Recognition using Modified Gradient Descent Technique of Neural Networks and Representation of Conjugate Descent for Training Patterns
145
158
71776
EN
Vijaypal
Dhaka
Computer Engineering, Reliance Ind. Ltd
Manu Pratap
Singh
ICIS, Dr. B.R.Ambedkar University
Journal Article
1970
01
01
The purpose of this study is to analyze the performance of Back propagation algorithm with changing training patterns and the second momentum term in feed forward neural networks. This analysis is conducted on 250 different words of three small letters from the English alphabet. These words are presented to two vertical segmentation programs which are designed in MATLAB and based on portions (1/2 and 2/3) of average height of words, for segmentation into characters. These characters are clubbed together after binarization to form training patterns for neural network. Network was trained by adjusting the connection strengths on each iteration by introducing the second momentum term. This term alters the process of connection strength fast and efficiently. The conjugate gradient descent of each presented training pattern was found to identify the error minima for each training pattern. The network was trained to learn its behavior by presenting each one of the 5 samples (final input samples having 26 × 5 = 130 letters) 100 times to it, thus achieved 500 trials indicate the significant difference between the two momentum variables in the data sets presented to the neural network. The results indicate that the segmentation based on 2/3 portion of height yields better segmentation and the performance of the neural network was more convergent and accurate for the learning with newly introduced momentum term.
http://www.ije.ir/article_71776_87f82747c43ce04d57d0b0c2848836c3.pdf
Materials and Energy Research Center
International Journal of Engineering
1025-2495
22
2
2009
06
01
Bi-Level Control Policy for Redundant Repairable Multicomponent System with Reneging, Set Up and Vacation
159
168
71779
EN
Susheel
Kumar
Madhu
Jain
Mathematics, Basic Science
Journal Article
1970
01
01
This paper deals with bi-level control policy and queuing analysis of a machine repair problem. The model is developed by incorporating mixed standbys (cold and warm), reneging, set up and vacation time. The repair facility consists of two heterogeneous repairmen in the system. The life and repair time of the failed units and also their set up times are assumed to be exponentially distributed. The steady state queue size distribution is obtained by using recursive method. Expressions are derived for the number of failed units in the queue and the average waiting time for repair, throughput, etc. By setting appropriate parameters, we deduce some special models.
http://www.ije.ir/article_71779_1bf8ce4e4b58396b124fbe0b1e987582.pdf
Materials and Energy Research Center
International Journal of Engineering
1025-2495
22
2
2009
06
01
Thermal Analysis of Laser Hardening for Different Moving Patterns
169
180
71781
EN
M.
Sistaninia
Laboratoire de simulation des matÃ©riaux, EPFL (Ecole Polytechnique FÃ©dÃ©rale de Lausanne
G. H.
Farrahi
School of Mechanical Engineering, Sharif University of Technology
https://orcid.org/00
Journal Article
1970
01
01
Transient thermal field in laser surface hardening treatment of medium carbon steel was analyzed by employing both three-dimensional analytical model and finite element model. In finite element model the laser beam was considered as a moving plane heat flux to establish the temperature rise distribution in the work-piece, while in analytical model laser beam was considered as an internal heat source. The numerical results were compared with the analytical results. In laser heat treatment of steel some methods are used to produce a wider and nearly uniform average irradiance profile. It may be achieved by rotating the beam optically, thereby producing an overlapping spiral track, or by dithering the beam (rocking the lens or mirror) perpendicular to the track, thus producing a zigzag pattern. In this paper, these models are used to cover the two mentioned patterns for laser hardening with Gaussian distribution, and to compare the results with the hardened region of bimodal and uniform distribution. The results show that dithering beam and rotating beam are useful for obtaining a uniform heat intensity distribution, if the parameters of dithering beam or rotating beam are properly chosen with the aid of these models. The diffusion process being a time dependent phenomenon, an interaction time of 15 ms was taken as a basis to determine the hardened region.
http://www.ije.ir/article_71781_0437ccd5315e7b6c2d55a2088199ac65.pdf
Materials and Energy Research Center
International Journal of Engineering
1025-2495
22
2
2009
06
01
Thermohydrodynamic Characteristics of Journal Bearings Running under Turbulent Condition
181
194
71784
EN
S.A.
Gandjalikhan Nassab
Mechanical Engineering, Shahid Bahonar University of Kerman
Behnaz
Maneshian
Mechanical Engineering, Aerospace Research Institute
Journal Article
1970
01
01
A thermohydrodynamic (THD) analysis of turbulent flow in journal bearings is presented based on the computational fluid dynamic (CFD) techniques. The bearing has infinite length and operates under incompressible and steady conditions. In this analysis, the numerical solution of Navier-Stokes equations with the equations governing the kinetic energy of turbulence and the dissipation rate, coupled with the energy equation in the lubricant flow and the heat conduction equation in the bearing are obtained. The AKN Low-Re k-ε turbulence model is used to simulate the mean turbulent flow field. Considering the complexity of the physical geometry, conformal mapping is used to generate an orthogonal grid and the governing equations are transformed to the computational domain. Discretized forms of transformed equations are obtained by the control volume method and solved by the SIMPLE algorithm. In this study, cavitation effects are also considered by using an appropriate cavitation model. The liquid fraction in the cavitated region is computed based on the continuity requirements and rather than the two-phase flow of lubricant in this region, a homogenous mixture with equivalent properties is assumed and the governing equations still apply in the cavitated region. From this method, the lubricant velocity, pressure and temperature distributions in the circumferential and cross film directions are obtained without any approximation. The numerical results are compared with experimental data and good agreement is found.
http://www.ije.ir/article_71784_f1e312088735fbaf7e29276b32edc47e.pdf
Materials and Energy Research Center
International Journal of Engineering
1025-2495
22
2
2009
06
01
Using Pattern Search Algorithm and Finite Element Method to Detect Rotor Cracks
195
204
71786
EN
Mohammad
Silani
Mechanical Engineering, Isfahan University of Technology
Hassan
Nahvi
Mechanical Engineering, Isfahan University of Technology
Journal Article
1970
01
01
The vibration pattern of a rotor system reflects the mechanical parameter changes in the system. Hence, the use of vibration monitoring is considered as a possible means of detecting the presence and growth of the cracks. In this paper, a pattern search based method for shaft crack detection is proposed and described which formulates the shaft crack detection as an optimization problem by means of the finite element method and utilizes the pattern search algorithm to search the solution. Using a direct search method avoids some of the weaknesses of the traditional gradient based analytical search method, including the difficulty in constructing well-defined mathematical models directly from practical inverse problems. First, a finite element code was developed for analyzing a rotor system with open cracks. To extract the flexibility matrix of an element containing cracks an exact integration scheme was adopted which is more accurate than the conventional methods. Then, the crack detection method was formulated as an inverse problem which can be solved by optimization algorithms. The numerical simulations suggest that good predictions of shaft crack location and depth are possible and the proposed method is feasible.
http://www.ije.ir/article_71786_3eed3c1e5199daabca346ff8d6feb3d7.pdf
Materials and Energy Research Center
International Journal of Engineering
1025-2495
22
2
2009
06
01
A New Technique for the Calculation of Colliding Vortex Rings
205
212
71788
EN
T.K.
Sheel
Mathematics, Shahjalal University of Science & Technology
Journal Article
1970
01
01
The present study involves a novel computational technique, regarding simultaneous use of the pseudo particle method, Poisson integral method and a special-purpose computer originally designed for molecular dynamics simulations (MDGRAPE-3). In the present calculations, the dynamics of two colliding vortex rings have been studied using the vortex method. The present acceleration technique allows the calculation of 107 vortex elements. The reconnection of the vortex rings was clearly observed, and the discretization error was nearly negligible.
http://www.ije.ir/article_71788_67637d32324406397452afb70318162d.pdf