
غلامرضا شهریار
حشمتی
author
بهمن
مهری
author
دارا
معظمی
author
علیرضا
ذکائی
author
text
article
1999
per
This paper is concerned with nonlinear third order O.D.E. of the from:
x'" + gl (x')x" + g2(X)X' + g3(t,x)=e(t)
where the functions gi , i = 1, 2, 3, and e(t) are continuous and periodic with respect to
t of periodic co. One of the most
important properties of the solution of the above equation is the existence of the periodic solution. In so doing we first construct the greens function and then transform the above equation into nonlinear integral equation. Using some type of fixed point theorem (Schauder), we conclude the existence of at last one solution with periodic boundary conditions.
X(i) (O)= x(i) (?) i = 0, 1, 2.
We extend this periodic boundary condition to a periodic solution using numerical method (RungeKutta) to approximate this periodic solution. It is
interesting to note that periodic solution of the above equation has a vast application
in engineering and physics.We only
us the mathematical model for brakes of heavy vehicle.
University College of Engineering
دانشکده فنی
08031026
33
v.
1
no.
1999
https://jfe.ut.ac.ir/article_15328_9e9c5e05079878606e63a1a61a285a2e.pdf

آرش
ابراهیمی
author
سهراب
شهزادی
author
text
article
1999
per
Capabilities for correlating image reconstruction, image mapping and threedimensional (3D) visualization, enable the neurosurgeon to simulate surgical procedures into a preoperative protocol to be used during surgery in real time computer monitor. In this paper use is made of a method, based on reconstruction and processing of serial magnetic Resonance images, as following steps: Segmentation of brain tissue, interpolation of slices and 3 D reconstruction of the
model. Interpolation method and 3 D
reconstruction of cortex surface of the segmented images are analyzed, processed and computing of interpolated slices proceeded by the shapebased interpolation procedures. One of the main parts of the
interpolation process is the estimation of
distance function of the binary cortex images. Morphological operators could reduce the computational time of distance function. Ray tracing and ray casting methods are developed from 3 D reconstruction of cortex surface images. There are some reports that ray casting methods has better ability to detect the
intricate cortex surface. On the other hand, images reconstructed by this method have convenient quality in reconstruction, but needs more time for processing.
University College of Engineering
دانشکده فنی
08031026
33
v.
1
no.
1999
https://jfe.ut.ac.ir/article_15329_320f9f951abf8420a88a3629a2124385.pdf

محمد خلج امیر
حسینی
author
فرخ حجت
کاشانی
author
محمود کمره
ای
author
text
article
1999
per
One of the important methods for reconstructing and imaging an unknown body is using the electromagnetic waves and measuring the . scattering, fields. This method is the same solution of the inverse scattering problem in electromagnetic. In this paper after reviewing the. inverse scattering problem, and the Born Iterative method for solving it, the effect of the important factors of measurement is studied. This factors are: frequency of transmitters, number of transmitters and receivers, angle of viewing and the noise of receivers. The simulated examples are in two dimensional space.
University College of Engineering
دانشکده فنی
08031026
33
v.
1
no.
1999
https://jfe.ut.ac.ir/article_15330_6253245e8d0bee98a0a5563e7d02ff79.pdf

بهزاد
مشیری
author
منصور هادی
زاده
author
text
article
1999
per
0In this paper, it is tried to present a complete model of a FMS (Flexible Manufacturing System) using petrinets; in continuation of the work, genetic algorithms have also been investigated to provide an optimal and rapid scheduling. In this research, all practical points existed in a typical FMS such as existance of CN C machines, robots and different load carriers like AGV and buffers have been considered.
In addition to above, the significant problems such as interactions between load carriers motions and/or interactions caused by robots navigation have also been considered in the model. Meanwhile, to obtain faster responses, different local and suboptimal approaches for scheduling issue have also been investigated.
University College of Engineering
دانشکده فنی
08031026
33
v.
1
no.
1999
https://jfe.ut.ac.ir/article_15331_b02e853d8b628e839dcfc01ef0933eed.pdf

حسین
ارفع
author
text
article
1999
per
Water potentials of the rivers are managed and controlled by construction of
the reservoir dams. If the river is long, its flow is high and the conditions for water usage of the river are provided, it is more advisable to construct several smaller dams on different locations on the river instead of one large dam at the outlet of the river valley. This decision can be made in order to shorten the distances of the transmit of the water and power yields of the river and it is meant more economical operation. The set of reservoirs constructed on a river or on its tributaries is named a system of reservoirs.
There are varieties of combinations which govern the relationships of the water usage of the system. Among the different combinations, the one that guarantees the most economical beneficial water usage is called the optimal operation of the system.
This article illustrates the application of the linear programming for optimal operation of such a system which is consisted of several sequent reservoir dams.
University College of Engineering
دانشکده فنی
08031026
33
v.
1
no.
1999
https://jfe.ut.ac.ir/article_15332_f25349b4028b2914e82bca5cadacf15d.pdf

محمد
رحیمیان
author
مرتضی اسکندری
قادری
author
علیرضا
حیدرپور
author
text
article
1999
per
The governing equations of the body which undergoes the heat and/or force shocks are the Navier's equation and energy one, which in coupled form, they are named coupled thermoelasticity equations. In this paper these equations are solved for a long axisymmetric cylinder. The boundary conditions are heat flow and/or surface stress on the inner boundary and that the heat isolated outer surface is free stress. Using the eigen values and eigen vectors of the matrix differential operator, the coupled
. thermoelasticity equations transform to uncoupled one. Using laplace transform the uncoupled equations are solved and the analytical solutions are obtained in laplace space. The inverse lap lace transform will be obtained in the companion paper using the numerical methods.
University College of Engineering
دانشکده فنی
08031026
33
v.
1
no.
1999
https://jfe.ut.ac.ir/article_15333_d43fb7ef9156f4568b7d08b6f42da833.pdf

محمد
رحیمیان
author
مرتضی اسکندری
قادی
author
علیرضا
حیدرپور
author
text
article
1999
per
Using numerical methods, the radial displacement, temperature and stresses for a long axisymmetric cylinder which have been analytically obtained in the companion paper are numerically evaluated and the results are prepared in the graphical from. In order to do this, it is needed to evaluate the inverse laplace transforms of the displacement and temperature functions. Because of the complexity of these functions in the lap lace space, they can not be evaluated analytically. So, in this paper, they are evaluated numerically. Using complex variables, the singular integrals are obtained considering the infinite limit of the integrals. The results are given for various heat and force loadings such as modified step function, Dirac delta functions and impact one.
University College of Engineering
دانشکده فنی
08031026
33
v.
1
no.
1999
https://jfe.ut.ac.ir/article_15334_1b3627755b14c3c9aaec2faff8468bdd.pdf

علی اصغر
حمیدی
author
گیتا
معینی
author
علی اصغر صدیق
زاده
author
text
article
1999
per
University College of Engineering
دانشکده فنی
08031026
33
v.
1
no.
1999
https://jfe.ut.ac.ir/article_15335_dd3f7017724eaa4a08092e3cb0015768.pdf

محمد علی
موسویان
author
غلامحسین
صدیفیان
author
text
article
1999
per
In general, small amounts of surfactants can change the mass transfer coefficients in the numerous processes such as vaporization, extraction and absorption.
This research is aimed at investigating the effect of the surfactants in the water vaporization. Aniline, Normal  amylalcohol, and 1Butanol were used. At first, in order to calibrate the apparatus, pure water mass diffusivity was measured.
Then the diffusion coefficients associated with surfactants were determined. The final results showed that the presence of these surfactants can decrease the water vaporization as much as 30%.
University College of Engineering
دانشکده فنی
08031026
33
v.
1
no.
1999
https://jfe.ut.ac.ir/article_15336_9db4c090b84405f0b5c4beddd1d78503.pdf

محمد فاروق
حسینی
author
text
article
1999
per
The proper method of investigating the applicability of a failure criterion, through laboratory results of uniaxial and triaxial compressive strength tests, is presented. The influencing factors and conditions have been discussed individually. The role of each factor has been shown using the experimental results obtained by the author.
The main factors on selecting laboratory data are as follows: brittleductile transition in rocks, the minimum number of data of each data set, the range of confining pressure in tri axial tests and finally the size and shape of tested specimens.
This paper is the outcome of a critical review of investigation methods of other researchers in this field, pointing on the weak points of previous works and suggesting solutions to the previous shortcomings.
It has been shown that neglecting the importance of the influencing factors leads to wrong conclusions.
The paper introduces the proper way of producing or selecting laboratory data to those who are interested or involved in the research works relating to the mechanical properties of rocks.
University College of Engineering
دانشکده فنی
08031026
33
v.
1
no.
1999
https://jfe.ut.ac.ir/article_15337_3c38c291311aaf11854891bc424154a7.pdf

سعید حشمتی
منش
author
سید فرشید کاشانی
بزرگ
author
text
article
1999
per
Microstructural evolution has been investigated in Si containing ?  Ti Al alloys after hot deformation and further annealing. Effective factors in thermomechanical processing such as deformation temperature, deformation ratio, and annealing temperature were studied. Isothermal deformation below the eutectic temperature resulted in inhomogeneous dynamic recrystallisation and fine equiaxed grains were produced in recrystallised areas and residual deformed lamellae elsewhere. During the deformation. the hard eutectic silicides play an important role in destruction of the as cast structure. Also the presence of the eutectic silicides and fine silicides produced by precipitation in the solid state restricts the size of grains produced by dynamic recrystallisation as well as by static recrystallisation on subsequent annealing and results in a fine grained structure.
University College of Engineering
دانشکده فنی
08031026
33
v.
1
no.
1999
https://jfe.ut.ac.ir/article_15338_07a75ac54b64cc5c49c6e8b1e1cb311c.pdf

مهرداد آقایی
خفری
author
رضا
محمودی
author
text
article
1999
per
University College of Engineering
دانشکده فنی
08031026
33
v.
1
no.
1999
https://jfe.ut.ac.ir/article_15339_bb72cdafc70e3530ce4e383d2fd65c2e.pdf

فرهاد جاوید
راد
author
محمود موسوی
مشهدی
author
text
article
1999
per
In the present paper effects of skew initial delamination length in DCB specimens on evaluating modc  I delamination fracture energy (GIc) were investigated. Delamination growth analysis incorporating finite element method is used to model delamination growth initiated from a skew front and determine loaddisplaceIl1ent  delamination length data for a prescribed GIc as delamination propagated along the specimen. Then, the standard test data reduction methods have been applied to the numerical data to evaluate the values of GIc for each position of delamination front.
It is seen that skew front progressively change to a curved front
during a few millimeter growth. Part of this growth occurs within the specimen which is not visible from the specimen edges where the delamination lengths were recorded during a test. Therefore, the load drop for this growth should not be related to the material behavior. It is also seen that the difference between delamination lengths measured at either side of the specimen can have a significant effect on GIc calculated by the standard methods. To eliminate this error in an actual test, it is suggested that the data for a first few millimeters of growth be neglected.
University College of Engineering
دانشکده فنی
08031026
33
v.
1
no.
1999
https://jfe.ut.ac.ir/article_15340_f54870fe23beca8800f738b7470f3abe.pdf

ناصر
سلطانی
author
محمد
نورین
author
text
article
1999
per
University College of Engineering
دانشکده فنی
08031026
33
v.
1
no.
1999
https://jfe.ut.ac.ir/article_15341_2e47efd0c1843e7a5343fc608c9aa4d1.pdf

دکتر محمد حسن
رحیمیان
author
text
article
1999
per

University College of Engineering
دانشکده فنی
08031026
33
v.
1
no.
1999
https://jfe.ut.ac.ir/article_15342_b9a3829f0b365ab46ccc42578f93f674.pdf