
محمودرضا حقی
فام
author
علیرضا
حاتمی
author
حمید
لسانی
author
text
article
1999
per
Reliability is one of the important factors in distribution planning and expansion. Due to high availability of components, input data in reliability assessment are fuzzy. In this paper an algorithm for reliability assessment in distribution systems is proposed with uncertainties in input data such as failure rates, repair times and operation of protective devices. By use of this procedure, reliability indices, membership functions of outage cost for load points, feeders and systems can be calculated. The proposed approach has been applied to electric network of north east of Tehran with satisfactory results.
University College of Engineering
دانشکده فنی
08031026
33
v.
3
no.
1999
https://jfe.ut.ac.ir/article_16851_daf6aa142b43987da1620756a7d7dd5e.pdf

محمود کمره
ای
author
پیمان
شهسواری
author
کوروش
کلانترزاده
author
text
article
1999
per
In this paper we explain how acoustical wave propagates from far sources under the sea. Normal mode method is one of the fittest methods for calculating the patch of propagating acoustical energy in low frequency; it is for layered area in which layers have the same characteristics and all of them are parallel to the horizon. Pressure and density of acoustical energy can be determined everywhere, using normal mode method together with boundary conditions in calculated propagating modes and summing these modes with coefficient which is dependent on the
depth of source. At the end, for some velocity profiles and actual and virtual density, application of this method is described.
University College of Engineering
دانشکده فنی
08031026
33
v.
3
no.
1999
https://jfe.ut.ac.ir/article_16852_1fcd2ae30a39a8acf725e71d8678d167.pdf

خسرو
برگی
author
اسدا...
نورزاد
author
علی طبائی
بفروئی
author
text
article
1999
per
An analytical mechanical model for cylindrical tanks is presented taking into consideration the effect of rigid base rocking motion and lateral translation. The liquid is assumed to be
homogeneous, inviscid, and
incompressible. Only rigid tanks were studied. Analytical expressions for the parameters of the model are given, and numerical values of these parameters are displayed in charts. The analysis includes both impulsive and connective pressures. The model can be used to evaluate the dynamic response of a rigid cylindrical tank subjected to earthquake loading with and without rigid base rocking motion.
University College of Engineering
دانشکده فنی
08031026
33
v.
3
no.
1999
https://jfe.ut.ac.ir/article_16853_9ad247cc410f200cf3023762005b6393.pdf

محمدرضا
بهاری
author
بابک کریم
دادیان
author
text
article
1999
per
Welded tubular joints are used in a wide range of onshore and offshore structures. However, insufficient information is available for the design of multiplanar connections between them. Stress Concentration Factors (SCF) should be applied to assess fatigue life of tubular connections that is necessary to indicate fatigue life of offshore jacket structures. Most researches have concentrated on uniplanar connections and there is not wholly accepted way to evaluate multiplanar connections. In practice, the latter is designed by considering them in separate planes, and calculating the least fatigue life. Neglecting the effect of outofplane bracing members on the overall behavior might provide conservative results. Using a three dimensional finite element modeling, a numerical research has been carried out to increase the insight into the static behavior of multiplanar joints. The paper aims at discussing above mentioned difference in SCF for multi planar connections should are they designed as uniplanar for two common types of tubular connections; i.e. TT and XX; the validity of the common practice and the affecting factors in office design are also explained.
University College of Engineering
دانشکده فنی
08031026
33
v.
3
no.
1999
https://jfe.ut.ac.ir/article_16854_9f221bc401ea1bdb8e84c9c49c5f5e59.pdf

عین ا...
شفیعی
author
غلامعباس
بارانی
author
محمد جواد
خانجانی
author
text
article
1999
per
Occurrence of frequent high peak floods in arid and semiarid regions with weak plant coverage causes density current containing fine sediment materials. Such current when meets a reservoir plunges under the still water due to high density relative to still water. Sedimentation in the plunge point of riverreservoir system elevates river bottom line, increases flood plain and swamp area, and decreases useful volume of reservoir.
In this study, by using dimensional analysis, plunge depth equation was determined. And by adapting a physical hydraulic model for slopes of one to eight percent, plunge depth were measured. A constant coefficient in the equation for all slopes was determined. The range of the constant coefficient varies from 0.6 to 2.01, such for the step slope less than one, for mild slope more than one and for critical slope almost equal to one. The equation along, with related constant coefficient can be used to compute plunge depth for different slopes.
University College of Engineering
دانشکده فنی
08031026
33
v.
3
no.
1999
https://jfe.ut.ac.ir/article_16855_e7ad76c9fc34a21db2de32b36c3672de.pdf

داود دوست
محمدی
author
بابک
امیدوار
author
محمد
رحیمیان
author
text
article
1999
per
An analytical model is introduced as to study the behavior of eccentrically braced frames. In this model the flange and web of IShaped link beam are considered separately. The web of link beam is modeled as a 2D element for which stiffness matrix can be calculated using finite element method. The web, therefore can be yielded in 8 Gauss points, and gradual yielding across the web will be predicated. The flange is modeled as a beam element. In addition, plastic hinge occurrence, geometric nonlinear effects, buckling of elements and Pdelta effects are included in the modeling of the other beamcolumn elements of the frame. The validity of the model is justified by comparing the results with the available reported experiments. Finally, some twospan frames have been analyzed with the link beam model to demonstrate the significance of using realistic models in determining the frame behavior such as ductility, internal forces and energy dissipation.
University College of Engineering
دانشکده فنی
08031026
33
v.
3
no.
1999
https://jfe.ut.ac.ir/article_16856_b04f5374b171ca48c4266cfe6e7fda67.pdf

حمید
مدرس
author
اسماعیل
جمشیدی
author
شکوفه
حکیم
author
text
article
1999
per
The spreading behavior of ionic surface active materials, SDS and CTAB and nonionic surface active materials, Tween 80 and Arkopal 15 on the water surface with large thickness is studied both theoretically and experimentally. It is shown that the distance traveled by the leading front of the spreading film depends on the surface tension of surface active material and underlying liquid and also on viscosity and density of the underlying liquid. The study of the distance traveled by different surface active materials on the water surface shows a good agreement between the experimental results and the proposed mathematical model.
University College of Engineering
دانشکده فنی
08031026
33
v.
3
no.
1999
https://jfe.ut.ac.ir/article_16857_c3d622189defeefc55a3d8d175ae3c4a.pdf

بهزاد حکیم
الهی
author
ناصر
سلطانی
author
text
article
1999
per
A thin cylinderical shell under thermal and mechanical shocks is considered. In cases that the characteristic times of structural and thermal disturbances are of comparable magnitudes, simultaneus solution of temperature and stress fields is required. For this purpose, the classical equations of coupled dynamic thermoelasticity of thin cylinderical shell are derived. These
equations include the dynamics
equilibrium equations of shells and
energy equations. Since there is no closed form solution for this problem, finite element method is used. The technique used is based on weak formulation of Galerkin weighted residual and Kantrovich approximation for space and time domains. Then governing dynamic equations of an element is derived and assembled for total domain in matrix form. Next, Newmark method is used for solving equations and from that radial and axial displacements, rotations and temperature distributions along cylinder length at various times are calculated. Some other unknowns such as forces, moments, axial and circumferential stresses and radial shear stresses may be found from nodal parameters. In this study, the effect of axial displacement is considered in governing equations. Second order thermal distributions through thickness is applied. Applied pressure, shear and thermal shocks are variables in term of time and longitudinal component of space. In this study, it was shown that the effects of coupling of equations could be considerable. Also, in some cases, neglecting axial displacement from equations was seen to produce large errors. The overall results compared well with previous works in special cases.
University College of Engineering
دانشکده فنی
08031026
33
v.
3
no.
1999
https://jfe.ut.ac.ir/article_16858_a8c8955927ed82241da3eddc9022d43c.pdf

محمود
شریعتی
author
مجید
میرزائی
author
text
article
1999
per
This paper presents the derivation and experimental verification of analytical expressions for assessment of fatigue crack closure. The expressions are obtained based on the modification of the RigidInsert Crack Closure (RICC) model for the loadline of the C(T) sepcimen. The formulation of the model results in a set of equations which can predict the closure load as well as the LoadCOD characteristics using the residual COD at zero load as a unique experimental input. The final form of the derived equations are rather complex and require a numerical solution. The equations are verified, both qualitatively and quantitatively, using different specimen sizes and 7075 aluminum alloy and specially designed experimental techniques
University College of Engineering
دانشکده فنی
08031026
33
v.
3
no.
1999
https://jfe.ut.ac.ir/article_16859_b11ef74d0ff542d04149a35b80a87d9e.pdf

محمد صادق
صادقپور
author
حمید
مهدیقلی
author
سیاوش
کاویانی
author
text
article
1999
per
To make sure from the correct functioning of the high head gates and, also, to determine hydrodynamic froces, such gates are hydraulic model tested during the design period. All the high head gates for the Iranian dams have been tested outside the country with high costs. Besides, the aerodynamic tests have also been introduced as a substitute for the hydraulic tests, in the recent years. With the two objectives of gaining technical
knowhow for the hydraulic model test of
the gates, and to verify the accuracy of
the aerodynamic model tests, the side
gate of the Marun dam’s bottom outlet
was hydraulic model tested. By
measuring the pressures in the proper
locations of the model gate and its
casting, and using the quality of the
Wuler numbers, pressures in the similar
points of the prototype gate was
calculated. These pressures were used to
calculate the hydrodynamic force applied
on the gate. The hydrodynamic forces of
different elements of the gate and the
resultant force, at different gate openings,
compare very well with the results
obtained from the aerodynamic model
test.
University College of Engineering
دانشکده فنی
08031026
33
v.
3
no.
1999
https://jfe.ut.ac.ir/article_16860_262b311bf7795fc17884fd612fdc6a3d.pdf

فرشاد
کوثری
author
امیررضا
فراهانی
author
text
article
1999
per
In this paper a parametric
investigation is carried out to study the
performance of annular fins made of
orthotropic materials. Effects of varying
the geometry, convective coefficient and
material properties are taken into
consideration. The fin temperature
distribution is obtained by finite
difference ADISOLR method. An
appropriate grid generation is employed
by the solution of Poisson’s equation to
better resolve the heat flux at the
boundaries.
University College of Engineering
دانشکده فنی
08031026
33
v.
3
no.
1999
https://jfe.ut.ac.ir/article_16861_920ecee819b05e9dcfbf0792bdfb1feb.pdf