Plastic instability in equibiaxial deformation of sheet metals
دکتر رضا
محمودی
author
text
article
1986
per
Plastic instability which results in the localization and failure of sheet metals has been
studied in equibiaxial stretching of commercial purity aluminium sheet. Attention was
focussed on two main industrial conditions of the material. These were representative of
the materials that could be processed by the commercial batchannealing process (slow
heating, long time) or by a continuous annealing process (fast heating, short time). The
instability strains were experimentally measured and compared with those predicted by
different instability criteria. The results have been analyzed on the basis of the
mechanical characteristics of the material under different conditions. It is concluded that
pressure instability can not be used as the extreme limit of forming and thus there is a
considerable amount of useful deformation after instability strain.
University College of Engineering
دانشکده فنی
0803-1026
54
v.
0
no.
1986
https://jfe.ut.ac.ir/article_26833_4cc57ac6c2ba5dde052b59da3531412e.pdf
Frame Alignment Procedure in Digital Transmission systems
دکتر ناصر
رضایی
author
مجید
صدری
author
text
article
1986
per
Every digital transmission system requires frame alignment. It is necessary to
identify the varius signal componets and to bring receiver into phase with respect to the
transmission format so that the digits can be properly assembled for demultiplexing. Fast
and reliable frame alignmant is important, and therefore has been a subject for study.
This paper a comprehensive analysis of frame alignment procedure used for time
division multiplex equiment complying with European standards (which is used in IRAN
and many other countries). The study complements the work of others on frame
alignment by presenting a more simplified method for understanding frame alignment
procedure. The approach derives the probability generating function of frame alignment
procedure from the generalized state transition diagram of Sitter. The probability
generating function is then used to estimate the average and variance of the timing
parameters. The principal transition times (out - of- frame detection time, maximum
average reframe time, false in - frame time and misframe time) is used as a performance
criteria for optimization of parameters. The effect of design criteria on various timing
parameters is presented graphically and a realistic example is considered.
University College of Engineering
دانشکده فنی
0803-1026
54
v.
0
no.
1986
https://jfe.ut.ac.ir/article_26834_8f0f139cc971696a899f6030a525a3ae.pdf
Difficulties in the Treatment of Copper Porphyry Ores
حسین نعمت
اللهی
author
text
article
1986
per
A high percentage of world copper production is obtained from porphyry copper
reserves, These reserves are characterized by: very high tonnage, greater horizontal
dimensions than vertical, association with stock like intrusion masses, dispersed minerals
in the porphyry mass and in its neighbor rocks, intense sericitization and inplace silicification.
The porphyry coppers are concentrated by flotation. The main problems in the
flotation of these ores are: slime, excessive pyrite, oxidized pyrite, oxide and oxidized
copper minerals,various of copper sulphide minerals and finally, operational parameters.
The present study deals with the effect of these trouble making factors in the flotation
process.
University College of Engineering
دانشکده فنی
0803-1026
54
v.
0
no.
1986
https://jfe.ut.ac.ir/article_26835_aea6e0cdca3ad9f84f698ba7647fdb62.pdf
Numerical Analysis of Combined Refraction and Diffraction of Waves
دکتر خسرو
برگی
author
مهندس جواد
ملک
author
text
article
1986
per
Refraction and Diffraction combination of Waves, is very important and applicable
problem in coastal engineering (e.g. for designing break - water). However, formulation
of this phenomen and numerical solution is very difficult.
In this study, a numerical algorithm based on the mild Slop sea bed theory is
presented to obtain the appropriate governing equations of combined Refraction Diffraction.
Also, a software has been prepared to solve these equations by finite
difference method in time domain. Finally comparison of the differents results is shown.
University College of Engineering
دانشکده فنی
0803-1026
54
v.
0
no.
1986
https://jfe.ut.ac.ir/article_26836_b6e22feba6347d962688491e9a42a700.pdf
Two - Dimensional Temperature Field in a Semi-Infinite Finned Wall
دکتر مجید
ملکی
author
جمشید
محرری
author
text
article
1986
per
In this paper, two-dimensional heat transfer in a semi-infinite wall with fins of
rectangular profile has been investigated. The conduction equations of the wall and fins
are solved simultaneously by a numerical method. The principal parameters of the
problem are the fin spacing, length, and fin-to-wall conductivity ratio. In this
investigation, the effect of these parameters on two-dimensional temperature field of the
wall and the fins, and on the fin performance has been discussed. The results indicate
that the temperature depression caused by the multifin array is larger than that of the
single-fin arrangement. Moreover, reduction of the fin spacing, increase in fin length and
thermal conductivity all have an enhancing effect on temperature depression. Finally,
the fin performance is directly proportional to the length, spacing, and thermal
conductivity of the fins.
University College of Engineering
دانشکده فنی
0803-1026
54
v.
0
no.
1986
https://jfe.ut.ac.ir/article_26837_08248e4eae42ec6fb198cca0023c141d.pdf
Simulation Of Rotating Disk Contactors (ROC) For Industrial
and Semi . Industrial Processes
حسین
بهمنیار
author
پریسا
خدیوپارسی
author
text
article
1986
per
In order to simulate the rotating disk contactor all hydrodynamic parameters,
dispersed phase hold-up, characteristic velocity, mean drop size, drop size distribution,
axial mixing and mass transfer have been taken into account. Mechanisms of mass
transfer (stagnant, circulating, oscillating drops) were used in this study. Column height
found from effect of mean drop size and drop size distribution have been compared.
University College of Engineering
دانشکده فنی
0803-1026
54
v.
0
no.
1986
https://jfe.ut.ac.ir/article_26838_87ee29126b75e618678607edc385bbe8.pdf
Two Dimensional Mathematical Model of Unsteady Flow in
Lakes and Estuaries Using Symmetrical Grid
حسین
سامانی
author
محمد علی بنی
هاشمی
author
text
article
1986
per
In this study, a method which is based on the integration of Navier-Stokes and
continuity equations has been used to develop the governing equations. In these
equations the Coriolis acceleration and the effect of wind also have been considered.
The main application of the model is to solve two dimensional problems with free
surface in the plane. The offshore engineering projects and the hydrodynamic problems
of lakes and estuaries can be mentioned as application examples of the model.
The required data are the geometry of the medium, bed roughness coefficient, wind
velocity and geographical coordinates of the medium. Since the problem to be solved is
basically unsteady, in addition to the boundary condition, initial conditions should also
be given.
Several numerical tests have been performed to check the model and quite
satisfactory results have been observed.
University College of Engineering
دانشکده فنی
0803-1026
54
v.
0
no.
1986
https://jfe.ut.ac.ir/article_26839_b2a37ffbf205cc5ef7063f02f90938ed.pdf
Prediction of Retrograde Condensation Using the SRK Equation of State
محمد مهدی منتظر
رحمتی
author
شهرام
اسلامی
author
text
article
1986
per
The SRK two-parameter cubic equation of state has been used for the calculation
of the equilibrium constant using the liquid and vapor fugacity coefficients for three
binary mixtures. Dew and bubble points have been determined using the equilibrium
constants and the phase envelope has been plotted showing dearly that retrograde
condenstaion occurs.
The following percent deviations have been obtained from the experimental values:
8.2% for carbon dioxide - monochloromethane binary system, 4% for the ethane heptane
binary system, and 2% for the ethane - octane binary system.
In view of the above comparisons, it seems that the SRK equation of state is
capable of predicting retrograde behavior with good accuracy.
University College of Engineering
دانشکده فنی
0803-1026
54
v.
0
no.
1986
https://jfe.ut.ac.ir/article_26840_cfb581ebba78ddb490ee4481d9a5a620.pdf