Materials and Energy Research Center
International Journal of Engineering
1025-2495
1735-9244
5
1
1992
05
01
Fundamental Solutions of Dynamic Poroelasticity and Generalized Termoelasticity
1
10
EN
G. F.
Dargush
Civil Engineering, State University of New York at Buffalo
hasnomail@ije.ir
Fundamental solutions of dynamic poroelasticity and generalized thermoelasticity are derived in the Laplace transform domain. For poroelasticity, these solutions define the solid displacement field and the fluid pressure in fluid-saturated media due to a point force in the solid and an injection of fluid in the pores. In addition, approximate fundamental solutions for short times are derived by analytically inverting the Laplace transform expressions. Finally numerical results are presented to highlight the essential features of the problem as well as to investigate the accuracy of the time domain solutions.
https://www.ije.ir/article_71052.html
https://www.ije.ir/article_71052_47a8b2ffcbaef420fd0e03fe301074ce.pdf
Materials and Energy Research Center
International Journal of Engineering
1025-2495
1735-9244
5
1
1992
05
01
Multilaminate Elastoplastic Model for Granular Media
11
24
EN
S. A.
Sadrnejad
Civil Engineering, Khaje Nasir Toosi University of Technology
sadrnejad@hotmail.com
A multilaminate based model capable of predicting the behavior of granular material on the basis of sliding mechanisms and elastic behavior of particles is presented. The capability of the model to predict the behavior of sand under arbitrary stress paths is examined. The influences of rotation of the direction of principal stress axes and induced anisotropy are included in a rational way without any additional hypotheses. The predicted numerical results of sand specimens in hollow cylindrical and true triaxial tests and also under undrained conditions are presented.
https://www.ije.ir/article_71053.html
https://www.ije.ir/article_71053_d95e954912d45db7f6478606022c5b7c.pdf
Materials and Energy Research Center
International Journal of Engineering
1025-2495
1735-9244
5
1
1992
05
01
Recent Developments in Discrete Event Systems
25
32
EN
K.
Inan
Electerical Engineering, Middle East Technical University
hasnomail@ije.ir
This article is a brief exposure of the process approach to a newly emerging area called "discrete event systems" in control theory and summarizes some of the recent developments in this area. Discrete event systems is an area of research that is developing within the interstices of computer, control and communication sciences. The basic direction of research addresses issues in the analysis and design of distributed intelligent systems operating within real time constraints. The article focuses on the concepts of an algebraic process approach and formulates supervisory control problems in this framework.
https://www.ije.ir/article_71054.html
https://www.ije.ir/article_71054_0e69a44ea4330c02df7a5e7e8417302e.pdf
Materials and Energy Research Center
International Journal of Engineering
1025-2495
1735-9244
5
1
1992
05
01
Quadrature Amplitude Modulated Digital Radio Transmission Modeling and Simulation
33
38
EN
M.
Kavehrad
, University Ottawa
m.kavehrad@psu.edu
Computer aided design and computer aided modeling tools are becoming increasingly important in the design and performance evaluation of communication systems. In this work, we report on the computer simulation modeling study of terrestrial digital microwave radio transmission, using Block Oriented System Simulator package (BOSS). The work concentrates on semi-analytical error rate evaluation in digital transmission Simulation results include time and frequency domain representations of various system outputs.
https://www.ije.ir/article_71055.html
https://www.ije.ir/article_71055_b219946a2ca0451d9bab61892aee2b90.pdf
Materials and Energy Research Center
International Journal of Engineering
1025-2495
1735-9244
5
1
1992
05
01
Structural and Mechanical Characterization of Austempered Cu - Sn Ductile Iron Alloys
39
48
EN
A.
Najafizadeh
Materials Engineering, Isfahan University of Technology
a-najafi@cc.iut.ac.ir
M. A.
Golozar
Materials Engineering, Isfahan University of Technology
golozar@cc.iut.ac.ir
The effect of heat treatment and alloying elements of copper and tin on the microstructure and mechanical properties of austempered ductile cast iron alloys is investigated. The austenitizing temperature of 890°C, the isothermal transformation (austempering) temperatures of 285, 335 and 375°C, and austempering times of 15, 30, 75 and 150 minutes are studied. The alloying elements of copper and tin are varied within the range of 0 -1.5% and 0 - 0.4%, respectively. The results obtained indicate that the microstructure and mechanical properties of austempered ductile Cu-Sn iron alloys are significantly influenced by the isothermal transformation time and temperature. The alloying elements of copper and tin have a pronounced effect on the matrix microstructure of as-cast and annealed ductile irons. These elements show no effect on the morphology of bainite in the austempered condition. However, the volume fraction of retained austenite in the austempered ductile iron alloys increase due to the addition of these elements. The mechanical properties of austempered ductile iron alloys are also significantly influenced by alloying elements. At austempering temperatures of 375 and 335°C, the 1% Cu - 0.4%Sn ductile iron alloy austempered for 75 minutes shows the optimum combination of mechanical properties. Conversely, at austempering temperature of 285°C, the 1% Cu - 0.2% Sn ducitile iron alloys austempered for 30 minutes represent the optimum combination of mechanical properties.
https://www.ije.ir/article_71056.html
https://www.ije.ir/article_71056_8a8e5fe8dc1b1a45cdac05c1cf4c8667.pdf
Materials and Energy Research Center
International Journal of Engineering
1025-2495
1735-9244
5
1
1992
05
01
Effect of Composition on the Recrystallization Behavior of if Steels During Simulated Hot Strip Rolling
49
60
EN
J. J.
Jonas
Materials Engineering, McGill University
hasnomail@ije.ir
A.
Najafizadeh
Materials Engineering, Isfahan University of Technology
a-najafi@cc.iut.ac.ir
Flow curves are generated in muti-pass torsion tests for a titanium stabilized and a niobium stabilized IF steel. Two types of test schedule are used, one based on plate rolling and the other approximating strip rolling. The purpose of the former is to define the three critical temperatures of steel rolling. The strip schedules are varied in order to investigate the influence of increasing the total finishing strain (from 2.1 to 3.2) and lowering the first finishing pass temperature (from 990 to 930°C) on microstructural evolution in these steels. All the tests are carried out at a strain rate of 2s-1. Under hot strip rolling conditions, static recrystallization is responsible for the high degree of interpass softening. During the final passes, dynamic recrystallization occurs to a degree that depends on the composition of the steel, the total finishing strain and the temperature. Subjected to the same strip rolling schedule, the niobium stabilized steel has a finer ferrite grain size than the IF steel stabilized with titanium.
https://www.ije.ir/article_71057.html
https://www.ije.ir/article_71057_580e86fefb1ee7766ad434d043c64298.pdf
Materials and Energy Research Center
International Journal of Engineering
1025-2495
1735-9244
5
1
1992
05
01
Prediction of Fluid Flow and Heat Transfer Characteristics Behind a Single Backward-Facing Step
61
68
EN
S.
Ahmed
Mechanical Engineering, Bangladesh University of Engineering & Technology
hasnomail@ije.ir
Numerical solutions based on standard finite volume method are presented for the study of heat transfer and fluid dynamic characteristics in turbulent flows behind a single sided backward-facing step. The calculation of the differential equations is performed using SIMPLE algorithm. For the turbulent quantities standard K-model is used. Predicted mean velocity profiles and reattachment lengths comply with the experimental data but significant deviation occurs in the predictions of turbulent intensities. The predicted heat transfer coefficient is in good agreement up to the reattachment point and downstream of that point it matches qualitatively.
https://www.ije.ir/article_71058.html
https://www.ije.ir/article_71058_0724e08b4b1b72c977000f8773b785c1.pdf
Materials and Energy Research Center
International Journal of Engineering
1025-2495
1735-9244
5
1
1992
05
01
Signal Prediction by Layered Feed - Forward Neural Network (RESEARCH NOTE).
69
74
EN
J. H.
Lu
Electerical Engineering, Southern Methodist University
hasnomail@ije.ir
In this paper a nonparametric neural network (NN) technique for prediction of future values of a signal based on its past history is presented. This approach bypasses modeling, identification, and parameter estimation phases that are required by conventional parametric techniques. A multi-layer feed forward NN is employed. It develops an internal model of the signal through a training operation involving past history of the considered signal. Training is performed using the back-propagation algorithm. The trained net is then used to do the forecast. Training is continued during operation to improve performance. The net performance is tested on signals generated by autoregressive (AR) and autoregressive moving average (ARMA) models of different orders and results are compared to optimal forecasts.
https://www.ije.ir/article_71059.html
https://www.ije.ir/article_71059_5a7d22e7adc6e834f34eb97bd7f334e1.pdf
Materials and Energy Research Center
International Journal of Engineering
1025-2495
1735-9244
5
1
1992
05
01
Discussion of Road Accidents in Iran (SHORT COMMINUCATION).
75
76
EN
T.P.
Hutchinson
Mathematics & Statistics, University of Technology, Sydney
hasnomail@ije.ir
Several comments are made regarding the recent papers by F. Ayati on road accidents in Iran.
https://www.ije.ir/article_71060.html
https://www.ije.ir/article_71060_829fc395d1d0c904cab39a377499ca05.pdf