eng
Science and Research Branch, Islamic Azad University, Tehran, Iran
International Journal of Industrial Mathematics
2008-5621
2008-563X
2014-10-28
6
4
275
284
4728
مقاله پژوهشی
Enhancement of Noise Performance in Digital Receivers by Over Sampling the Received Signal
A. Y. Hassan
ashraf.fahmy@bhit.bu.edu.eg
1
S. M. Shaaban
2
Faculty of Engineering, Benha university, Benha, Egypt.
Faculty of Engineering, Menoa University, Shebin Elkom, Egypt.
In wireless channel the noise has a zero mean. This channel property can be used in the enhancement of the noise performance in the digital receivers by oversampling the received signal and calculating the decision variable based on the time average of more than one sample of the received signal. The averaging process will reduce the effect of the noise in the decision variable that will approach to the desired signal value. The averaging process works like a lter that reduces the noise power at its output according to its averaging interval. Although the power spectrum of the noise does not change according to the averaging process, the noise variance at the decision variable will be smaller than the channel noise variance. This paper studies this idea and show how the performance of digital receivers can be enhanced by oversampling the received signal. This paper shows another treatment method to the noise problem in digital modulation systems.
http://ijim.srbiau.ac.ir/article_4728_ec7586c5e44f926d722eefdcc2dec6b1.pdf
Wireless channel
Noise performance
Signal
Averaging interval
eng
Science and Research Branch, Islamic Azad University, Tehran, Iran
International Journal of Industrial Mathematics
2008-5621
2008-563X
2014-11-01
6
4
285
296
4737
مقاله پژوهشی
Double diffusive reaction-convection in viscous fluid layer
Vinod K. Gupta
vinodguptabhu@gmail.com
1
A. K. Singh
2
Department of Mathematics, Faculty of Science, Banaras Hindu University, Varanasi -221005, India.
Department of Mathematics, Faculty of Science, Banaras Hindu University, Varanasi -221005, India
In the present study, the onset of double diffusive reaction-convection in a uid layer with viscous fluid, heated and salted from below subject to chemical equilibrium on the boundaries, has been investigated. Linear and nonlinear stability analysis have been performed. For linear analysis normal mode technique is used and for nonlinear analysis minimal representation of truncated Fourier series is used. The effect of Lewis number, solute Rayleigh number, reaction rate and Prandtl number on the stability of the system is investigated. A weak nonlinear theory based on the truncated representation of Fourier series method is used to nd the heat and mass transfer.
http://ijim.srbiau.ac.ir/article_4737_f67aaa915dae18d82e02d54a867222ca.pdf
Double diffusive convection
Chemical reaction
viscous fluid
eng
Science and Research Branch, Islamic Azad University, Tehran, Iran
International Journal of Industrial Mathematics
2008-5621
2008-563X
2014-11-01
6
4
297
306
4738
مقاله پژوهشی
MHD rotating heat and mass transfer free convective flow past an exponentially accelerated isothermal plate with fluctuating mass diffusion
K. Jonah Philliph
1
M. C. Raju
2
A. J. Chamkha
achamkha@yahoo.com
3
S. V. K. Varma
4
Department of H\&S, Mother Theresa Institute of Engineering \& Technology, Palamaner - 517408, Andhra Pradesh, India.
Department of H\&S, Annamacharya Institute of Technology and Sciences, (Autonomous), Rajampet - 516126, Andhra Pradesh, India.
Manufacturing Engineering Department, The public authority for applied Education and training, Shuweikh - 70654 Kuwait.
Department of Mathematics, S. V. University, Tirupati - 517502, Andhra Pradesh, India.
In this paper, we have considered the problem of rotating, magnetohydrodynamic heat and mass transfer by free convective flow past an exponentially accelerated isothermal vertical plate in the presence of variable mass diffusion. While the temperature of the plate is constant, the concentration at the plate is considered to be a linear function with respect to time t. The plate is assumed to be exponentially accelerated with a prescribed velocity against the gravitational field. The governing equations are solved by using Laplace transform technique and the effect of various physical parameters on the flow quantities are studied through graphs and the results are discussed. With the aid of the velocity, temperature and concentration fields the expressions for skin friction, rate of heat transfer in the form of Nusselt number and rate of mass transfer in the form of Sherwood number are derived and the results are discussed with the help of tables.
http://ijim.srbiau.ac.ir/article_4738_384c5235cdaac3f80b169502d227a918.pdf
MHD
Rotation
heat and mass transfer
Exponentially accelerated plate
eng
Science and Research Branch, Islamic Azad University, Tehran, Iran
International Journal of Industrial Mathematics
2008-5621
2008-563X
2014-12-01
6
4
307
314
4785
مقاله پژوهشی
On approximation of the fully fuzzy fixed charge transportation problem
A. Mahmoodirad
alimahmoodirad@yahoo.com
1
H. Hassasi
2
G. Tohidi
3
M. Sanei
4
Department of Mathematics, Masjed-Soleiman Branch, Islamic Azad University, Masjed-Soleiman, Iran.
Department of Mathematics, Central Tehran Branch, Islamic Azad University, Tehran, Iran.
Department of Mathematics, Central Tehran Branch, Islamic Azad University, Tehran, Iran.
Department of Mathematics, Central Tehran Branch, Islamic Azad University, Tehran, Iran.
In the literature hardly any attention is paid to solving a fuzzy fixed charge transportation problem. In this paper, we consider the fully fixed-charge transportation problem and try to find both the lower and upper bounds on the fuzzy optimal value of such a problem in which all of the parameters are triangular fuzzy numbers. To illustrate the proposed method, a numerical example is presented.
http://ijim.srbiau.ac.ir/article_4785_98491778e1481863da0d8c527cea98ce.pdf
Fixed charge transportation
triangular fuzzy numbers
Fuzzy transportation problem
Ranking function
eng
Science and Research Branch, Islamic Azad University, Tehran, Iran
International Journal of Industrial Mathematics
2008-5621
2008-563X
2014-12-01
6
4
315
320
4792
مقاله پژوهشی
Homotopy approximation technique for solving nonlinear Volterra-Fredholm integral equations of the first kind
SH. Sadigh Behzadi
shadan\_ behzadi@yahoo.com
1
Department of Mathematics, Qazvin Branch, Islamic Azad University, Qazvin, Iran.
In this paper, a nonlinear Volterra-Fredholm integral equation of the first kind is solved by using the homotopy analysis method (HAM). In this case, the first kind integral equation can be reduced to the second kind integral equation which can be solved by HAM. The approximate solution of this equation is calculated in the form of a series which its components are computed easily. The accuracy of the proposed numerical scheme is examined by comparing with other analytical and numerical results. The existence, uniqueness and convergence of the proposed method are proved. Example is presented to illustrate the efficiency and the performance of the homotopy analysis method.
http://ijim.srbiau.ac.ir/article_4792_c1491aee2e319b92871f373335cd1205.pdf
Integral equations of the first kind
Volterra and Fredholm integral equations
Homotopy analysis method.
eng
Science and Research Branch, Islamic Azad University, Tehran, Iran
International Journal of Industrial Mathematics
2008-5621
2008-563X
2014-12-01
6
4
321
327
4836
مقاله پژوهشی
Evaluating the efficiency and classifying the fuzzy data: A DEA based approach
S. Kordrostami
krostami@guilan.ac.ir
1
G. Farajpour
2
M. Jahani Sayyad Noveiri
3
Department of Applied Mathematics, Lahijan branch, Islamic Azad University, Lahijan, Iran.
Department of Industrial Engineering, Parand branch, Islamic Azad University, Tehran, Iran.
Department of Applied Mathematics, Lahijan branch, Islamic Azad University, Lahijan, Iran.
Data envelopment analysis (DEA) has been proven as an efficient technique to evaluate the performance of homogeneous decision making units (DMUs) where multiple inputs and outputs exist. In the conventional applications of DEA, the data are considered as specific numerical values with explicit designation of being an input or output. However, the observed values of the data are sometimes imprecise (i.e. input and output variables cannot be measured precisely) and data are sometimes flexible (measures with unknown status of being input or output are referred to as flexible measures in the literature). In the current paper a number of methods are proposed to evaluate the relative efficiency and to identify the status of fuzzy flexible measures. Indeed, the modified fuzzy DEA models are suggested to accommodate flexible measures. In order to obtain correct results, alternative optimal solutions are considered to deal with the fuzzy flexible measures. Numerical examples are used to illustrate the procedure.
http://ijim.srbiau.ac.ir/article_4836_991280d1e4d3b379ff0af4d6a82e4339.pdf
Data Envelopment Analysis
Fuzzy numbers
flexible measures
Inputs, Outputs.
eng
Science and Research Branch, Islamic Azad University, Tehran, Iran
International Journal of Industrial Mathematics
2008-5621
2008-563X
2014-12-01
6
4
329
332
4851
مقاله پژوهشی
Fixed points for total asymptotically nonexpansive mappings in a new version of bead space
A. Razani
razani@ipm.ir
1
Department of Mathematics, Collage of Science, Takestan Branch, Islamic Azad University, Takestan, Iran.
The notion of a bead metric space is defined as a nice generalization of the uniformly convex normed space such as $CAT(0)$ space, where the curvature is bounded from above by zero. In fact, the bead spaces themselves can be considered in particular as natural extensions of convex sets in uniformly convex spaces and normed bead spaces are identical with uniformly convex spaces. In this paper, we define a new version of bead space and called it $CN$-bead space. Then the existence of fixed point for asymptotically nonexpansive mapping and total asymptotically nonexpansive mapping in $CN$-bead space are proved. In other word, Let $K$ be a bounded subset of complete $CN$-bead space $X$. Then the fixed point set $F(T)$, where $T$ is a total asymptotically nonexpansive selfmap on $K$, is nonempty and closed. Moreover, the fixed point set $F(T)$, where $T$ is an asymptotically nonexpansive selfmap on $K$, is nonempty.
http://ijim.srbiau.ac.ir/article_4851_6efc2b8da788fecc2e99242823e362c5.pdf
Bead space
$CAT(0)$ space
fixed point
Total asymptotically nonexpansive mapping.
eng
Science and Research Branch, Islamic Azad University, Tehran, Iran
International Journal of Industrial Mathematics
2008-5621
2008-563X
2014-12-01
6
4
333
343
4852
مقاله پژوهشی
New concepts on the fuzzy linear systems and an application
M. Ganbari
mojtaba.ghanbari@gmail.com
1
Department of Mathematics, Aliabad Katoul Branch, Islamic Azad University, Aliabad Katoul, Iran.
As we know, developing mathematical models and numerical procedures that would appropriately treat and solve systems of linear equations where some of the system's parameters are proposed as fuzzy numbers is very important in fuzzy set theory. For this reason, many researchers have used various numerical methods to solve fuzzy linear systems. In this paper, we define the concepts of midpoint and radius functions for a fuzzy number, midpoint and radius vectors for a fuzzy number vector and midpoint and radius systems for a fuzzy linear system. All these new definitions are defined based on the parametric form of fuzzy numbers. Then, by these new concepts, we propose a simple method to solve a fuzzy linear system and obtain it's algebraic solution. Also, we present a sufficient condition for the obtained solution vector to be always a fuzzy vector. Finally, several numerical examples are given to show the efficiency and capability of the proposed method.
http://ijim.srbiau.ac.ir/article_4852_3dde21522261294c54a6a7e1de7b8583.pdf
Fuzzy linear system
Midpoint function
Radius function
Midpoint vector
Radius vector
Midpoint system
Radius system
eng
Science and Research Branch, Islamic Azad University, Tehran, Iran
International Journal of Industrial Mathematics
2008-5621
2008-563X
2014-12-01
6
4
345
350
4853
مقاله پژوهشی
Partial Differential Equations applied to Medical Image Segmentation
B. Bagheri
bagheri@iaufb.ac.ir
1
R. Ezzati
2
Department of Mathematics, Firoozkooh Branch, Islamic Azad University, Firoozkooh, Iran.
Department of Mathematics, Karaj Branch, Islamic Azad University, Karaj, Iran.
This paper presents an application of partial differential equations(PDEs) for the segmentation of abdominal and thoracic aortic in CTA datasets. An important challenge in reliably detecting aortic is the need to overcome problems associated with intensity inhomogeneities. Level sets are part of an important class of methods that utilize partial differential equations (PDEs) and have been extensively applied in image segmentation. A kernel function in the level set formulation aids the suppression of noise in the extracted regions of interest and then guides the motion of the evolving contour for the detection of weak boundaries. The speed of curve evolution has been significantly improved with a resulting decrease in segmentation time compared with traditional implementations of level sets, and are shown to be more effective than other approaches in coping with intensity inhomogeneities. We have applied the Courant Friedrichs Levy (CFL) condition as stability criterion for our algorithm.
http://ijim.srbiau.ac.ir/article_4853_4aa5b6670e48f28f9e12b4f022b9bbe6.pdf
Partial differential equations
Image segmentation
Level-sets
Abdominal
Thoracic aorta.
eng
Science and Research Branch, Islamic Azad University, Tehran, Iran
International Journal of Industrial Mathematics
2008-5621
2008-563X
2014-12-01
6
4
351
360
4975
مقاله پژوهشی
Mean value theorem for integrals and its application on numerically solving of Fredholm integral equation of second kind with Toeplitz plus Hankel Kernel
N. Mikaeilvand
mikaeilvand@iauardabil.ac.ir
1
S. Noeiaghdam
2
Department of Mathematics, Ardabil Branch, Islamic Azad University, Ardabil, Iran.
Young Researchers and Elite Club, Tabriz Branch, Islamic Azad University, Tabriz, Iran.
The subject of this paper is the solution of the Fredholm integral equation with Toeplitz, Hankel and the Toeplitz plus Hankel kernel. The mean value theorem for integrals is applied and then extended for solving high dimensional problems and finally, some example and graph of error function are presented to show the ability and simplicity of the method.
http://ijim.srbiau.ac.ir/article_4975_d2ed826e86a755376aba55eae2316d12.pdf
Fredholm Integral Equations
Toeplitz plus Hankel Kernel
Mean Value Theorem for Integrals