2008
32
4
4
0
PREDICTION ALGORITHM FOR TORQUE RIPPLE REDUCTION IN DTCBASED DRIVES
2
2
In direct torque control, the selection of an applied voltage vector is based on the measuredparameters at the beginning of the sampling period. The delay between the measurement and the application of the voltage vector is the origin of an extra torque ripple. In this paper, a new predictive controller is proposed for compensating this delay and reducing the torque ripple. The stator current is measured twice in each sampling period and its expected value at the end of the period is predicted according to a linear extrapolation algorithm. Therefore, none of the machine parameters are used in the prediction, and consequently, the algorithm is quite robust against machine parameter variations. The calculation of the electromagnetic torque is performed using the predicted value of the stator current. Therefore, the selection of the voltage vector is more realistic and prevents extra torque ripple. This controller is quite suitable for high power drives where the sampling frequency is low, and there is enough time for the extra measurements. Simulation and experimental results which confirm the ability of this method to considerably reduce the torque ripple are presented.
1

343
355


SH.
KABOLI
Electrical Engineering Department, Sharif University of Technology, Tehran, I. R. of Iran
Electrical Engineering Department, Sharif
Iran
kaboli@sharif.edu


M. R.
ZOLGHADRI
Electrical Engineering Department, Sharif University of Technology, Tehran, I. R. of Iran
Electrical Engineering Department, Sharif
Iran


P.
ESKANDARI
Electrical Engineering Department, Sharif University of Technology, Tehran, I. R. of Iran
Electrical Engineering Department, Sharif
Iran


D.
ROYE
Polytechnic Institute of Grenoble, France
Polytechnic Institute of Grenoble, France
Iran
Induction motor drive
direct torque control
torque ripple
predictive controller
(Aσ )Δ DOUBLE SEQUENCE SPACES VIA ORLICZ FUNCTIONS AND DOUBLE STATISTICAL CONVERGENCE
2
2
The aim of this paper is to introduce and study a new concept of strong double Δ ( A ) σ convergence sequences with respect to an Orlicz function, and some properties of the resulting sequencespaces were also examined. In addition, we define the Δ ( A ) σ statistical convergence and establish someconnections between the spaces of strong double Δ ( A ) σ convergence sequences and the space of doubleΔ ( A ) σ statistical convergence.
1

357
367


E.
SAVAS
Istanbul Ticaret University, Department of Mathematics, Uskudar, Istanbul, Turkey
Istanbul Ticaret University, Department of
Turkey
ekremsavas@yahoo.com


R. F.
PATTERSON
Department of Mathematics and Statistics, University of North Florida, Jacksonville, Florida 32224, USA
Department of Mathematics and Statistics,
United States
Orlicz function
invariant means
almost convergence
double statistical convergence
LINEAR PROGRAMMING PROBLEM WITH INTERVAL COEFFICIENTS AND AN INTERPRETATION FOR ITS CONSTRAINTS
2
2
In this paper, we introduce a Satisfaction Function (SF) to compare interval values on the basis ofTseng and Klein’s idea. The SF estimates the degree to which arithmetic comparisons between two intervalvalues are satisfied. Then, we define two other functions called Lower and Upper SF based on the SF. Weapply these functions in order to present a new interpretation of inequality constraints with intervalcoefficients in an interval linear programming problem. This problem is as an extension of the classical linear programming problem to an inexact environment. On the basis of definitions of the SF, the lower and upper SF and their properties, we reduce the inequality constraints with interval coefficients in their satisfactory crisp equivalent forms and define a satisfactory solution to the problem. Finally, a numerical example is given and its results are compared with other approaches
1

369
390


A.
ABBASI MOLAI
Faculty of Mathematics and Computer Science, Amirkabir University of
Technology, Hafez Avenue, Tehran, I. R. of Iran
Faculty of Mathematics and Computer Science,
Iran
abbasi54@aut.ac.ir


E.
KHORRAM
Faculty of Mathematics and Computer Science, Amirkabir University of
Technology, Hafez Avenue, Tehran, I. R. of Iran
Faculty of Mathematics and Computer Science,
Iran
Interval number
inequality relation
equality relation
satisfaction function
interval linear programming
AUTOCORRELATION FOR A CLASS OF POLYNOMIALS WITH COEFFICIENTS DEFINED ON T
2
2
In this work we deal with the coefficients of A (e it ) 2 , where A is in a class of polynomialshaving Unimodular coefficients. We first present a technique that calculates lower bounds for particularautocorrelations and then in a more general case we present an upper bound for their maximal order.
1

391
396


M.
TAGHAVI
Department of Mathematics, College of Sciences, Shiraz University, Shiraz, I. R. of Iran
Department of Mathematics, College of Sciences,
Iran
taghavi@math.susc.ac.ir
Autocorrelation
frequency
Fouier coefficient
DOSIMETRIC EVALUATION OF A NEWLY DEVELOPED RADIOCHROMIC FILM FOR RADIATION PROCESSING
2
2
In order to improve the performance of a newly developed radiochromic film, GIC79, somedosimetric characteristics of this film have been studied based on relevant standard practice. The presentstudy describes some parameters that may affect the dosimeter response before, during, and after irradiation. The effect of absorbed dose rate on dosimeter response was determined by irradiating dosimeters at low absorbed dose rates with gamma rays. Calibration irradiations of dosimeters were performed with both gamma rays and also electrons to determine the effect of large difference absorbed dose rates on dosimeter response. In addition, post irradiation stability was obtained and also the temperature and humidity effects on the dosimeter response during the storage time prior to irradiation and post irradiation have been investigated
1

397
401


A.
AKHAVAN
Radiation Applications Research School, Nuclear Science and Technology Research Institute,
P.O. Box 113653486 Tehran, I. R. of Iran
Radiation Applications Research School, Nuclear
Iran
azakhavan@aeoi.org.ir


M.
SOHRABPOUR
Department of Energy Engineering, Sharif University of Technology, Tehran, I. R. of Iran
Department of Energy Engineering, Sharif
Iran


M.
SHARIFZADEH
Radiation Applications Research School, Nuclear Science and Technology Research Institute,
P.O. Box 113653486 Tehran, I. R. of Iran
Radiation Applications Research School, Nuclear
Iran
msharifzadeh@aeoi.org.ir
Dosimetry
film dosimeter
radiochromic film
gamma radiation
electron beam
ON EINSTEIN (α,β )METRICS
2
2
– In this paper we consider some (α ,β ) metrics such as generalized Kropina, Matsumoto and F (α β )2α = + metrics, and obtain necessary and sufficient conditions for them to be Einstein metrics when βis a constant Killing form. Then we prove with this assumption that the mentioned Einstein metrics must beRiemannian or Ricci flat.
1

403
412


B.
REZAEI
Department of Mathematics and Computer Science of AmirKabir University, Tehran, I. R. of Iran
Department of Mathematics and Computer Science
Iran
arazavi@cic.aut.ac.ir


A.
RAZAVI
Department of Mathematics and Computer Science of AmirKabir University, Tehran, I. R. of Iran
Department of Mathematics and Computer Science
Iran


N.
SADEGHZADEH
Department of Mathematics and Computer Science of AmirKabir University, Tehran, I. R. of Iran
Department of Mathematics and Computer Science
Iran
Einstein Finsler metrics
(α
β )  metrics
Schur lemma
IONOSPHERIC ABSORPTION OF HF RADIO WAVE IN VERTICAL PROPAGATION
2
2
In this study, absorption of high frequency radio waves in the ionospheric plasma have beeninvestigated. The wave equation was obtained in terms of ionospheric parameters. The numerical values ofthe absorption have been calculated for 4 MHz, 4.5 MHz and 5 MHz waves. The necessary parameters forcalculation have been obtained using an International Reference Ionosphere (IRI) Model. The altitudinal,diurnal, seasonal and the variations of absorption with frequency have been examined. The calculations showthat the highest absorption occurs in the Dregion. The absorption is higher in summer than in other seasonsand is maximum at daylight. In addition, absorption decreases with the increase of frequency.
1

413
419


I.
UNAL
Department of Science Teaching, Faculty of Education, Inonu Univ., 44280 Malatya, Turkey
Department of Science Teaching, Faculty of
Turkey
iunal@inonu.edu.tr,


O.
OZCAN
Department of Physics, Faculty of Science and Arts, Firat Univ., 23169 Elazig, Turkey
Department of Physics, Faculty of Science
Turkey


M.
CANYILMAZ
Department of Physics, Faculty of Science and Arts, Firat Univ., 23169 Elazig, Turkey
Department of Physics, Faculty of Science
Turkey
Ionosphere
HF wave
Absorption
PROJECTIVELY RELATED EINSTEIN FINSLER SPACES
2
2
The main objective of this paper is to find the necessary and sufficient condition of a given Finslermetric to be Einstein in order to classify the Einstein Finsler metrics on a compact manifold. The consideredEinstein Finsler metric in the study describes all different kinds of Einstein metrics which are pointwiseprojective to the given one. This study has resulted in the following theorem that needs the proof of threeprepositions. Let F be a Finsler metric (n > 2) projectively related to an Einstein nonprojectively flatFinsler metric F , then F is Einstein if and only if F = λ F whereλ is a constant. A Schur type lemma isalso proved.
1

421
429


N.
SADEGHZADEH
Department of Mathematics and Computer Science of AmirKabir University, Tehran, I. R. of Iran
Department of Mathematics and Computer Science
Iran
nasrin_sadeghi@cic.aut.ac.ir


A.
RAZAVI
Department of Mathematics and Computer Science of AmirKabir University, Tehran, I. R. of Iran
Department of Mathematics and Computer Science
Iran


B.
REZAEI
Department of Mathematics and Computer Science of AmirKabir University, Tehran, I. R. of Iran
Department of Mathematics and Computer Science
Iran
arazavi@cic.aut.ac.ir
Projectively related Finsler metrics
projectively flat
Einstein Finsler metric
VELOCITIES OF DUAL HOMOTHETIC EXPONENTIAL MOTIONS IN D3*
2
2
In this paper the concept of Homothetic Dual Exponential Motions in D3 is discussed and theirvelocities obtained. Due to the way in which the matter is presented, the paper gives some formula and factsabout dual exponential motions which are not generally known
1

431
434


V.
ASIL
Department of Mathematics Faculty of Art and Science Fırat University, 23119 Elazıg, Turkey
Department of Mathematics Faculty of Art
Turkey
vasil@firat.edu.tr,
Dual number
dual vector
homothetic motion
exponential transformation
BOUND STATE ENERGY OF DELTAFUNCTION POTENTIAL: A NEW REGULARIZATION SCHEME
2
2
In this letter we have proposed a new regularization scheme to deal with the divergent integralsoccurring in the quantum mechanical problem of calculating the bound state energy of the deltafunctionpotential in two and three dimensions. Based on the Schwinger parameterization technique we argue thatthere are no infinities even in D dimensions. In this way we were able to compare our proposal with theSchwinger regularization approch.
1

435
438


A.
JAHAN
Department of Physics, Amirkabir University of Technology, P. O. Box 158754413, Tehran, I. R. of Iran
Department of Physics, Amirkabir University
Iran
jahan@aut.ac.ir


M.
JAFARI
Islamic Azad University, Urmia branch, Urmia, I. R. of Iran
Islamic Azad University, Urmia branch, Urmia,
Iran
Deltafunction potential
bound state energy
smeared propagators
ON RQUADRATIC FINSLER METRICS
2
2
We prove that every Rquadratic metric of scalar flag curvature with a dimension greater than twois of constant flag curvature. Then we show that generalized DouglasWeyl metrics contain Rquadraticmetrics as a special case, but the class of Rquadratic metric is not closed under projective transformations
1

439
443


B.
NAJAFI
Department of Science, Shahed University, Tehran, I. R. of Iran
Department of Science, Shahed University,
Iran
najafi@shahed.ac.ir


B.
BIDABAD
Department of Mathematics and Computer Science, Amir Kabir University, Tehran, I. R. of Iran
Department of Mathematics and Computer Science,
Iran


A.
TAYEBI
Department of Mathematics, Faculty of Science, The University of Qom, Qom, I. R. of Iran
Department of Mathematics, Faculty of Science,
Iran
Rquadratic metric
Landsberg metric
generalized DouglasWeyl metric