2014
6
1
1
17
Review of the methods for evaluating congestion in DEA and computing output losses due to congestion
2
2
Data Envelopment Analysis (DEA) is a branch of management, concerned with evaluating the performances of homogeneous Decision Making Units (DMUs). The performances of DMUs are affected by the amount of sources that DMUs used. Usually increases in inputs cause increases in outputs. However, there are situations where increase in one or more inputs generate a reduction in one or more outputs. In such situations there is congestion in inputs or production process. In this study, we review the approaches that are available in the DEA literature for evaluating congestion. Also we introduce a model to compute output losses due to congestion. Then, we present the results of the mentioned models on an empirical example and interpret the results.
1

1
17


H.
Zare Haghighi
Department of Mathematics, Science and Research Branch, Islamic Azad University, Tehran, Iran
Department of Mathematics, Science and Research
Iran
zarehaghighi.srbiau@gmail.com


M.
Khodabakhshi
Department of Mathematics, Faculty of Mathematical Sciences, Shahid
Beheshti University, G.C., Tehran, Iran.
Department of Mathematics, Faculty of Mathematical
Iran


G. R.
Jahanshahloo
Department of Mathematics, Science and Research Branch, Islamic Azad University, Tehran, Iran
Department of Mathematics, Science and Research
Iran
Data Envelopment Analysis
Congestion
Inefficiency
Decision Making Unit
Solving fully fuzzy linear programming
2
2
In this paper, a new method is proposed to find the fuzzy optimal solution of fully fuzzy linear programming (abbreviated to FFLP) problems. Also, we employ linear programming (LP) with equality constraints to find a nonegative fuzzy number vector x which satisfies Ax =b, where A is a fuzzy number matrix. Then we investigate the existence of a positive solution of fully fuzzy linear system (FFLS).
1

19
26


M.
Otadi
Department of Mathematics, Firoozkooh Branch, Islamic Azad University, Firoozkooh, Iran
Department of Mathematics, Firoozkooh Branch,
Iran
mahmoodotadi@yahoo.com
fuzzy sets
linear programming
Fully fuzzy linear system
Numerical solution of the system of Volterra integral equations of the first kind
2
2
This paper presents a comparison between variational iteration method (VIM) and modfied variational iteration method (MVIM) for approximate solution a system of Volterra integral equation of the first kind. We convert a system of Volterra integral equations to a system of Volterra integrodi®erential equations that use VIM and MVIM to approximate solution of this system and hence obtain an approximation for system of Volterra integral equations. Some examples are given to show the pertinent features of this methods.
1

27
35


A.
Armand
Department of Mathematics, Science and Research Branch, Islamic Azad University, Tehran, Iran
Department of Mathematics, Science and Research
Iran
atefeh.armand@ymail.com


Z.
Gouyandeh
Department of Mathematics, Science and Research Branch, Islamic Azad University, Tehran, Iran
Department of Mathematics, Science and Research
Iran
Volterra integral equation of the first kind
Variational iteration method
Modified variational iteration method
A Random Walk with Exponential Travel Times
2
2
Consider the random walk among N places with N(N  1)/2 transports. We attach an exponential random variable Xij to each transport between places Pi and Pj and take these random variables mutually independent. If transports are possible or impossible independently with probability p and 1p, respectively, then we give a lower bound for the distribution function of the smallest path at point log N as Np is large.
1

37
40


R.
Kazemi
Department of Statistics, Imam Khomeini International University, Qazvin, Iran
Department of Statistics, Imam Khomeini Internatio
Iran
kazemi@ikiu.ac.ir
Smallest path
Random Walk
Pure birth process
Random recursive trees
Approximate solution of the stochastic Volterra integral equations via expansion method
2
2
In this paper, we present an efficient method for determining the solution of the stochastic second kind Volterra integral equations (SVIE) by using the Taylor expansion method. This method transforms the SVIE to a linear stochastic ordinary differential equation which needs specified boundary conditions. For determining boundary conditions, we use the integration technique. This technique gives an approximate simple and closed form solution for the SVIE. Expectation of the approximating process is computed. Some numerical examples are used to illustrate the accuracy of the method.
1

41
48


M.
Khodabin
Department of Mathematics, Karaj Branch, Islamic Azad University, Karaj, Iran
Department of Mathematics, Karaj Branch,
Iran
mkhodabin@kiau.ac.ir


K.
Maleknejad
Department of Mathematics, Karaj Branch, Islamic Azad University, Karaj, Iran
Department of Mathematics, Karaj Branch,
Iran


T.
Damercheli
Department of Mathematics, Karaj Branch, Islamic Azad University, Karaj, Iran
Department of Mathematics, Karaj Branch,
Iran
Taylor series expansion
Stochastic Volterra integral equation
Itˆo integral
FGP approach to multi objective quadratic fractional programming problem
2
2
Multi objective quadratic fractional programming (MOQFP) problem involves optimization of several objective functions in the form of a ratio of numerator and denominator functions which involve both contains linear and quadratic forms with the assumption that the set of feasible solutions is a convex polyhedral with a nite number of extreme points and the denominator part of each of the objective functions is nonzero in the constraint set. In this paper, we extend the procedure as suggested by Lachhwani (Proc. Nat. Acad. Sci. India, 82(4), 317322) based on fuzzy goal programming approach for the solution of multi objective quadratic fractional programming (MOQFP) problem. The proposed technique is simple, ecient and requires less computational work. In the proposed FGP model formulation, corresponding objectives of equivalent multi objective programming problem are transformed into fuzzy goals membership functions) by means of assigning an aspiration level to each of them and suitable membership function is defined for each objectives. Then achievement of the highest membership value of each of fuzzy goals is formulated by minimizing the sum of negative deviational variables. The proposed methodology is illustrated with numerical example in order to support the proposed methodology.
1

49
57


K.
Lachhwani
Department of Mathematics, Government Engineering
College, Bikaner 334004, India.
Department of Mathematics, Government Engineering
Iran
kailashclachhwani@yahoo.com
Multiple objective quadratic fractional programming
Fuzzy Goal programming
membership function
Negative deviational variable
On edge CoPI indices
2
2
In this paper, at first we mention to some results related to PI and vertex CoPI indices and then we introduce the edge versions of CoPI indices. Then, we obtain some properties about these new indices.
1

59
64


A.
Arjomandfar
Islamic Azad University, Shahre Rey Branch, Tehran,
Iran.
Islamic Azad University, Shahre Rey Branch,
Iran


O.
Khormali
Mathematics and Informatics Research Group,
ACECR, Tarbiat Modares University, B.O. Box: 14115
343, Tehran, Iran.
Mathematics and Informatics Research Group,
ACECR,
Iran
VertexPI index EdgePI indices
Molecular graph
Vertex CoPI indices
Efficiency Measurement in TwoStage Network Structures Considering Undesirable Outputs
2
2
Since data envelopment analysis (DEA) introduced in 1970s, it has been widely applied to measure the efficiency of a wide variety of production and operation systems. Recently DEA has been extended to examine the efficiency of decision making units (DMUs) with twostage network structures or processes, where the outputs from the first stage are intermediate measures that make up the inputs of the second stage. Many researchers developed several DEA based models for evaluating the efficiencies of such systems. This paper considers evaluation of the general twostage network structures, while each stage may produce undesirable output, in addition to desirable ones. The developed model is applied to Green Hen poultry chain in Guilan province, Iran.
1

65
71


A.
Amirteimoori
Department of mathematics, Islamic Azad University, Rasht branch, Rasht, Iran
Department of mathematics, Islamic Azad University
Iran


A.
ToloieEshlaghi
Department of Management and Economics, Islamic Azad University, Science and Research Branch, Tehran, Iran
Department of Management and Economics, Islamic
Iran


M.
Homayoonfar
Department of Management and Economics, Islamic Azad University, Science and Research Branch, Tehran, Iran
Department of Management and Economics, Islamic
Iran
Twostage Network
Data Envelopment Analysis
Undesirable output
Efficiency Evaluation
Decision Making Unit
Dynamical System and SemiHereditarily Hypercyclic Property
2
2
In this paper we give conditions for a tuple of commutative bounded linear operators which holds in the property of the Hypercyclicity Criterion. We characterize topological transitivity and semihereiditarily of a dynamical system given by an ntuple of operators acting on a separable infinite dimensional Banach space .
1

73
78


K.
Jahedi
Department of Mathematics,
Shiraz Branch, Islamic Azad University, Shiraz, Iran
Department of Mathematics,
Shiraz Branch,
Iran
mjahedi80@yahoo.com
Tuple
Hypercyclic vector
Hypercyclicity Criterion
Hereditarily hypercyclicity
Hynamical system
Periodic point
Optical properties of silicon nano layers by using Kramers Kronig method
2
2
Silicon thin layers are deposited on glass substrates with the thickness of 103 nm, 147 nm and 197 nm. The layers are produced with electron gun evaporation method under ultrahigh vacuum condition. The optical Reectance and the Transmittance of produced layers were measured by using spectrophotometer. The optical functions such as, real and imaginary part of refractive index, real and imaginary part of dielectric constant, real and imaginary part of conductivity, absorption coeficient and optical band gap energy are calculated basing on the KramersKronig relations. The void fractions of the silicon lms are calculated by using Aspnes theorem. The effect of layer thickness on optical properties of silicon thin lms is investigated.
1

79
84


H.
Kangarlou
Department of Physics, Urmia Branch, Islamic Azad
University, Urmia, Iran.
Department of Physics, Urmia Branch, Islamic
Iran
h.kangarlou@iaurmia.ac.ir
Silicon
Optical properties
KramersKronig relations
Thin films