Geothermal Energy
زین العابدین
نجات
author
text
article
1974
per
An introduction to geothermal energy is given III this article where the
techniques of research, exploration and utilization of source of energy will be
discussed in following articles.
This series of articles are the result of knowledge and experience gained
in Japan for the period of eleven weeks where the author benefited a scholarship through University of Tehran.
University College of Engineering
دانشکده فنی
08031026
30
v.
0
no.
1974
https://jfe.ut.ac.ir/article_26549_e567eeacff7e21783d1fcea87c8caffd.pdf
Stability of equilibrium. in nonlinear differential equations
دکتر نصرالله
تابنده
author
text
article
1974
per
In this article stability of equilibrium in the systems of nonlinear differential
equations is studied. Through several theorems and examples some criteria
for the stability of these systems are given. In this study we consider both
autonomous and nonautonomous systems.
University College of Engineering
دانشکده فنی
08031026
30
v.
0
no.
1974
https://jfe.ut.ac.ir/article_26550_2c315d3849459ca7fc0cd2d6777321b8.pdf
A Least Square Mode Matching Technique for Waveguide iscontinuities
همایون
عریضی
author
text
article
1974
per
The fields III various sections of a waveguide network are approximated
by their truncated modal expansions. The magnitude squared of each expression of the boundary conditions is integrated over the respective interfaces. The sum of these integrals is a quadratic function (called error function) of only the unknown modal amplitudes. The minimization of this function reduces to the solution of a linear equation which is directly obtainable from the boundary conditions. The unique minimum of the error function represents the best mode matching procedure in the least square sense. This technique is readily applicable to most waveguide discontinuity problems. However, it is applied here to the off set junction of two parallel plate waveguides and two rectangular waveguides with mode and current probe excitations. A weighting factor which multiplies the error due to the magnetic field is investigated and conservation of real power is utilized as a criterion for its selection.
University College of Engineering
دانشکده فنی
08031026
30
v.
0
no.
1974
https://jfe.ut.ac.ir/article_26551_d0c4ab669e23348616de1e1c0df58108.pdf
Earthing of TelephoDe EschaDge Office
PART ONE:
Measurement of earth resistivity by finding the voltage
distribution on its surface
یدالله
ارضی
author
text
article
1974
per
Nowadays for many purposes an earthing system in telephone exchange
office will be designed such as, transmission, protection and lessen the amount of crosstalk, so that is the reason why these kind of matters have put in an appearance seriously.
For example in the case of prositive pole of battery crosstalk will be
reduced. In telecommunication lines some of the speech currents may go from one line to the others through earth and as a result cause crosstalk. But if one of the poles of exchange battery is earthed, the path of leakage currents will be returned to the line and consequently reducing crosstalk.
The amount of earth resistance estimated to be below O. 5 n for the large
offices having a capacity about 10,000 subscribers and more.
It is common to say that acquiring this value is rather difficult referring
to the different kinds of soil.
In that case, a lot of countries prefere to design a system with a high
amount of resistance from the view point of economy. According to C. C. I. T. T. recommendations, measurements are shown that the lead sheath of cable are able to reduce it by 60 90 per cent. But referring to the decision of cable factories, which are going to change lead sheath to PE, they will automatically be canceled.
For this reason designing a group electrodes will be very important.
There are many factors effecting upon earthing resistance, which among
them soil resistivity plays the main role.
To the best of the author's knowledge, the soil properties are very changeable
and not really under control.
To tell the truth estimation of future value IS the main difficulty upon
our designing.
In this article we've shown different methods for measuring earth resistivity and acquaintance with stratification of earth layers to find a suitable
method for selection of electrodes.
University College of Engineering
دانشکده فنی
08031026
30
v.
0
no.
1974
https://jfe.ut.ac.ir/article_26552_a8fa3bd43a695a7561ad33ccb6a12f2c.pdf
Mass Transfer With Simultaneous Chemical Reaction
مرتضی
سهرابی
author
طاهره
کاغذچی
author
text
article
1974
per
A phenomenon of mass transfer with chemical reaction takes place whenever
two phases which are not at chemical equilibrium with one another
are brought into contact. Such phenomena are made up of a number of elementary
steps, which may be summarised as follows.
(i) Diffusion of one or more reactants from the bulk of phase I to the
interface between the two phases.
(ii) Diffusion of the reactants from the interface towards the bulk of
phase 2.
(iii) Chemical reaction within phase 2.
(iv) Diffusion of reactants initially present within phase 2, and/or of
reaction products, within phase 2 itself due to concentration gradients which
are set up by the chemical reaction.
Steps (ii) , (iii) and (iv) may take place simultaneously, and thus mutually
interfere; the overall phenomenon resulting from steps (ii) , (iii) and (iv) takes
place in series with step (i). If step (i) is rate controlling, the overall rate is
not influenced by the chemical reaction, and the process may be regarded as a simple mass transfer phenomenon which is not influenced by the reaction rate.
The analysis of mass transfer with chemical reaction is of interest when
the overall phenomenon resulting from steps (ii), (iii) and (iv) is ratecontrolling.
Chemical reactions which accompany mass transfer between phases are
usually classified as, slow, fast and instantaneous.
In this paper the" nature of these reactions is described and the mathematical
models related to such phenomena are presented and discussed.
University College of Engineering
دانشکده فنی
08031026
30
v.
0
no.
1974
https://jfe.ut.ac.ir/article_26553_bb08ba66695c8c197ed7ebf580b09454.pdf
Transmissionloss Formula for Economic Dispatch Calculations
فرخ حبیبی
اشرفی
author
text
article
1974
per
In economic dispatch study, when transmissionloss IS also considered,
partial differential derivatives of transmissionloss with respect to generating plant
output powers appear in the coordination equations. Obviously, an attempt for
expressing transmissionlosses as a function of generating plant outputs simplifies
the calculations. In this paper a method based on Kron's six reference frames,
and Kirchmayers developments on the calculation of loss formula is described.
In a bus reference frame transmission network is expressed as:
E =z I
We have to eliminate the individual load currents as variables, since
the final result should involve only generator powers. First the sum of the load
currents is defined as a total equivalent load, and then it is assumed that each
load current remains a constant complex fraction of the total equivalent load.
By applying Kron's transformation theory to the equation (1) a new formulation
for the transmission network ;will be obtained which involves only generator
currents :
E=ZIG
The real losses of the transmission network may be calculated as follows:
PL=Re(E IG*)=Re(IG Z I *)=Re(i * ZI )
substituting IG=Id+j Ig and Z=R+jX into equation (3) and using the rules
of matrix theory results to :
PL=Id ( )Id+Ig ( )Ig2Id ( )Ig
It is noted that only the symmetric past of the R and skewsymmetric part of
the X contribute to real loss.
Finally, to express PL in terms of generator powers J another transformation
is performed on the equeation (4) which puts PL into the desired form:
Pl=p BP
where the elements of B matrix are caned transmissionloss formula Coefficients.
Also procedures for representation of sourcereactive characteristics and
representation of loads are briefly discussed.
University College of Engineering
دانشکده فنی
08031026
30
v.
0
no.
1974
https://jfe.ut.ac.ir/article_26554_2656d395fe4d1613a86fd74d22e393af.pdf
A Comprative study of the Chemical State
of 32p and 35s in Potassium Chloride Crystals
مسعود
کسرائی
author
text
article
1974
per
When potassium chloride is neutron irradiated in a reactor several nuclear
reactions take place. The following reactions have been most widely investigated:
(1) 35CI (n , p) 35s
(2) 35CI (n , a) 32p
In this article the chemical states of 32p and 358 have been compared using
the available litereture and some data obtained in this laboratory. The results
generally show that in no case areduced form of 32p is found in the irradiated
potassium chloride crystal. While in case of 358 reduced as well as oxidized
forms are observed. The results are interpreted in terms of the reactivity of
phosphorus and sulphur for electrons in the lattice.
University College of Engineering
دانشکده فنی
08031026
30
v.
0
no.
1974
https://jfe.ut.ac.ir/article_26555_a32d53c24c4f865b3e2e7448f42cd22d.pdf
Least Squares Adjustment with the use of Matrix Algebra
Method A: Observation Equations Summary
مهندس علی اصغر
شریفی
author
text
article
1974
per
Statistics has proved that when you increase number of observations
the mean of accidental errors goes to zero, in other words with statistical terms
we can say the expected value of accidental errors is zero
n
?i
E{?}=lim =0 .
n
Increasing the number of observed quantities will cause another problem, we will
have more equations than it is necessary to solve for unknown parameters.
Here is the point that mathematical solution differs from computation in
experimental sciences. The later method is the least squares solution. In this
me thod all the observed quantities are used in such a way that if we find
differences between observed quantities and the adjusted values of these quantities
(residuals), the sum of squares of residuals be minimum. We can summarize
this method by it's two major characteristics:
1The solution is unique and independent of the path, and the order
of equations.
2  The sum of squares of residuals is minimum.
The classic method of least squares (as we call it) can be found in such
books like geodesy, mathematical statistics, and numerical analysis. With the
application of matrix algebra we present the method of least squares adjustment
in different way, however the principle is the same, but it does have some
advantages. Let us summarize weaknesses of the classical method as bellow:
1  With classical method computation is slow and uneconomical.
2  The simultaneous adjustment of large networks is very difficult and
actualy imposible, therefore the network have to be devided in blocks, and
adjust each block respect to the previous one. This will cause a kind of controversy
with the first principle, because the final results depend on the path
and the starting point of adjustment.
3  It is difficult to analyse the accuracy of computation, and the accuracy
of the adjusted values.
4  Enforcing the effect of correlated observations (the effect of covariances)
is difficult and actually imposible.
In the method of least squares adjustment with the use of matrix algebra
most of the computations are systematic kind wich can be done by electronic
computers very fast. There are only two parts which shoud have to be found
or estimated by us:
1To estimate a weight matrix (P) or variancecovariance matrix of
observations ( Lb= . P ) by the informations we have about instrument,
operator, and outer circumstances.
2To find and write down a suitable mathematical structure (mathematical
model).
MATHEMATICAL MODEL
Mathematical model is some functions that exist between observations
and parameters. The mathematical model for observation equations is a special
kind, and that is when each observed quantity can be written as a function of
some parameters.
La=f(Xa)
Where X, is a vector of adjusted parameters with u components (number of
parameters), and La is avector of adjusted observations with n (number of
observations) components. The other notations that we are going to use are:
Xo , the initial approximate values of parameters chosen arbitrarily before
adjustment.
The differences of Xa, and Xo , or the variation of parameters are
X=X X
The measured quantities are denoted by vector L with n components
using the following subscripts:
Lb , the measured values,
La' the adjusted values,
Lo , the values computed from values X, through the mathematical model
Lo=f(xo).
The differences of these sets are denoted as :
L=LOLb
V=LaLb residuals.
We can rewrite the mathematical model (I) interms of L, and X,
Lb+V=F(XoX)
After expanding it we get
Lb+V=F(XO)+AX
where A is a matrix with n rows and u columns, the elements of A are partial
derivatives of measured quantities with respect to the parameters.
A
X =XO
Since
Lo=F(Xo), and L=LoLb
equation (2) can be wirtten as
V=AX+L
The principle of lea
University College of Engineering
دانشکده فنی
08031026
30
v.
0
no.
1974
https://jfe.ut.ac.ir/article_26556_a62d77996924d8c56d929259c584c4ce.pdf

مرتضی مومن
زاده
author
text
article
1974
per

University College of Engineering
دانشکده فنی
08031026
30
v.
0
no.
1974
https://jfe.ut.ac.ir/article_26557_1f88b8497c4018468f1fce92de692ea4.pdf
La cODlparaison entre les systeDles
AcideBase et oxydoreducteur conjugues
دکتر جمشید
مفیدی
author
text
article
1974
per
Les systemes conjugues (AcideBase) ont ete connus depius longtemps
mais ses applications dans le domaine d'oxydo vreducteur sont assez recentes .
Entre ces deux systernes, n'existent pas une analogie tot ale , et, on
remarque aussi des differences. Cidessous, details des analogies et des differences
sont constlatees.
1) analogies:
a)  Dans un systerne conjugue, si un corps est fort, celiu qui est conjugue
sera faible; c'est a dire, si l'acide est fort, la base conjuguee sera faible, ou, si
l'oxydant est faible, Ie reducteur conjugue sera fort.
b) Dans les systemes conjugues, les solvants ant des roles analogues
(echanges d'ions ovec les solvants).
2) differences.
a) La reaction d'echanges protons se fait assez rapidement, tandisque
celle d'electrons, se produit d'une facon plus lente, si bien que un oxydant ou
un reducteur tres fort peut exister en milieu aqueux.
b) La reaction d'autoprotolyse est toujours reversible, et celIe d'autoredox,
suivat les cas, ont des valeurs relatives de constates d'equibbres grandes ou petites.
University College of Engineering
دانشکده فنی
08031026
30
v.
0
no.
1974
https://jfe.ut.ac.ir/article_26558_d4e144ffe75ce5a919475c3c4441a00a.pdf
Les ophiolites du zagros et les conditions de lour mise en place
حسین معین
وزیری
author
حسین
شیخی
author
text
article
1974
per
University College of Engineering
دانشکده فنی
08031026
30
v.
0
no.
1974
https://jfe.ut.ac.ir/article_26559_9ce283a932a611d0e9f4d3133564d171.pdf
The Development of the Palazoic in South West Asia
سهراب
شهریای
author
text
article
1974
per
University College of Engineering
دانشکده فنی
08031026
30
v.
0
no.
1974
https://jfe.ut.ac.ir/article_26560_d2b45358f68aac2d66e9a0fa24177236.pdf
Environment of Deposition and Sedimentary Petrology of the
Cambrian System in a Part of South Central Alborz, Iran
بیژن
اسفندیاری
author
text
article
1974
per
Faculty of Science, University of Tehran
For the purpose of this study 160 rock thin sections, as well as many
hand  specimens, were studied and examined. The Cambrian system in the
area is consisting of the Labun and the Mila Formations. R. L. Folk's classification
scheme have been used in the sedimentary petrologic study of the specimens.
General conditions of the sedimentary environment during the Cambrian
time has been described and interpreted.
The Labun Formation which is consisting of three members, has a
composition varying from quartzite to arkose, and its maturity is ranging from
mature to sub mature. Few local dikes of diabasic composition have been
recognized in this Formation. It is concluded that the environment of deposition
of this Formation was of oxidizing conditions and the deposits are of platform
kind.
The Mila Formation does not have complete outcrop of the four members
present in this area at every locality. This is mainly due to faulting, which
has caused the omission of some of the members of this Formation. Mila Formation
is a typical deposit of marine origin The conditions of deposition of this
formation was of varying depth and general reducing environment.
University College of Engineering
دانشکده فنی
08031026
30
v.
0
no.
1974
https://jfe.ut.ac.ir/article_26561_7364f0e12fe2199caa9d96c19638da5f.pdf

ناصر
توحیدی
author
text
article
1974
per

University College of Engineering
دانشکده فنی
08031026
30
v.
0
no.
1974
https://jfe.ut.ac.ir/article_26562_d008013f1dedf66a41ea22f9a16c3a92.pdf

مرتضی
حسینیان
author
text
article
1974
per

University College of Engineering
دانشکده فنی
08031026
30
v.
0
no.
1974
https://jfe.ut.ac.ir/article_26563_1c3c69d8fb326e71f45a9f544dc39d14.pdf

دکتر جمشید
کامران
author
text
article
1974
per

University College of Engineering
دانشکده فنی
08031026
30
v.
0
no.
1974
https://jfe.ut.ac.ir/article_26564_e7c87dca2827c974c2c659e8a057d91d.pdf

محمد علی
رحمتی
author
text
article
1974
per

University College of Engineering
دانشکده فنی
08031026
30
v.
0
no.
1974
https://jfe.ut.ac.ir/article_26565_4a388446ff1ceacdc3424c0cdb2c8298.pdf

unknown
author
text
article
1974
per

University College of Engineering
دانشکده فنی
08031026
30
v.
0
no.
1974
https://jfe.ut.ac.ir/article_26566_aa51a099c3ccdcf61ed99475ebd3751b.pdf