18
2008-4889
Iran University of Science & Technology
116
Material Managment
Experimental Study and Three-Dimensional Numerical Flow Simulation in a Centrifugal Pump when Handling Viscous Fluids
ShojaeeFard
M. H.
Boyaghchi
F. A.
Ehghaghi
M. B.
1
11
2006
17
4
53
60
19
07
2010
In this paper the centrifugal pump performances are tested when handling water and viscous oils as Newtonian fluids. Also, this paper shows a numerical simulation of the three-dimensional fluid flow inside a centrifugal pump. For these numerical simulations the SIMPLEC algorithm is used for solving governing equations of incompressible viscous/turbulent flows through the pump. The k-ε turbulence model is adopted to describe the turbulent flow process. These simulations have been made with a steady calculation using the multiple reference frames (MRF) technique to take into account the impeller- volute interaction. Numerical results are compared with the experimental characteristic curve for each viscous fluid. The data obtained allow the analysis of the main phenomena existent in this pump, such as: head, efficiency and power changes for different operating conditions. Also, the correction factors for oils are obtained from the experiment for part loading (PL), best efficiency point (BEP) and over loading (OL). These results are compared with proposed factors by American Hydraulic Institute (HIS) and Soviet :::union::: (USSR). The comparisons between the numerical and experimental results show good agreement.
117
Material Managment
Information and Covariance Matrices for Multivariate Pareto (IV), Burr, and Related Distributions
YARI
GH.
JAFARI
M. D
1
11
2006
17
4
61
69
19
07
2010
Main result of this paper is to derive the exact analytical expressions of information and covariance matrix for multivariate Pareto, Burr and related distributions. These distributions arise as tractable parametric models in reliability, actuarial science, economics, finance and telecommunications. We showed that all the calculations can be obtained from one main moment multidimensional integral whose expression is obtained through some particular change of variables. Indeed, we consider that this calculus technique for that improper integral has its own importance.
118
Material Managment
A Numerical Method for Backward Inverse Heat Conduction Problem With two Unknown Functions
Shidfar
A.
Zakeri
Ali
1
11
2006
17
4
71
74
19
07
2010
This paper considers a linear one dimensional inverse heat conduction problem with non constant thermal diffusivity and two unknown terms in a heated bar with unit length. By using the WKB method, the heat flux at the end of boundary and initial temperature will be approximated, numerically. By choosing a suitable parameter in WKB method the ill-posedness of solution will be improved. Finally, a numerical example will be presented.
119
Material Managment
A Layer DEA Model for Measuring and Improving the Efficiency in the Presence of Special Decision Making Units
Alirezaee
M.R.
Mir-Hassani
S.A
1
11
2006
17
4
75
79
19
07
2010
In the evaluation of non-efficient units by Data Envelopment Analysis (DEA) referenced Decision Making Units (DMU’s) have an important role. Unfortunately DMU’s with extra ordinary output can lead to a monopoly in a reference set, the fact called abnormality due to the outliers' data. In this paper, we introduce a DEA model for evaluating DMU’s under this circumstance. The layer model can result in a ranking for DMU’s and obtain an improving strategy leading to a better layer.
120
Material Managment
The Lie Algebra of Smooth Sections of a T-bundle
Nadjafikhah
M.
Salimi Moghaddam
H. R.
1
11
2006
17
4
81
85
19
07
2010
In this article, we generalize the concept of the Lie algebra of vector fields to the set of smooth sections of a T-bundle which is by definition a canonical generalization of the concept of a tangent bundle. We define a Lie bracket multiplication on this set so that it becomes a Lie algebra. In the particular case of tangent bundles this Lie algebra coincides with the Lie algebra of vector fields.