Amirkabir University of Technology
AUT Journal of Modeling and Simulation
2588-2953
2588-2961
42
1
2010
04
01
Calculation for Energy of (111) Surfaces of Palladium in Tight Binding Model
1
4
EN
Ali
Roohforouzi
Kavoos
Mirabbaszadehii
10.22060/miscj.2010.179
In this work calculation of energetics of transition metal surfaces is presented. The tight-binding model is employed in order to calculate the energetics. The tight-binding basis set is limited to d orbitals which are valid for elements at the end of transition metals series. In our analysis we concentrated on electronic effects at temperature T=0 K, this means that no entropic term will be presented and since we study unrelaxed structures, no elastic deformation contribution will be present either. Density of states is calculated for atoms at the surface and in the bulk for palladium by using the recursion method, when the potential includes only first and second nearest neighbor interactions. The surface energy of fcc (111) surfaces of Pd is also calculated.
Local Density of States,Tight binding Model,Surface energy,Recursion Method
http://miscj.aut.ac.ir/article_179.html
http://miscj.aut.ac.ir/article_179_fc9db245e5adc131e1456176cccd5388.pdf
Amirkabir University of Technology
AUT Journal of Modeling and Simulation
2588-2953
2588-2961
42
1
2010
04
01
Near Pole Polar Diagram of Points and its Duality with Applications
5
10
EN
Bahram
Sadeghi Bighami
Ali
Mohadesii
10.22060/miscj.2010.181
In this paper we propose a new approach to plane partitioning with similar features to those of Polar Diagram, but we assume that the pole is close to the sites. The result is a new tessellation of the plane in regions called Near Pole Polar Diagram NPPD. Here we define the (NPPD) of points, the dual and the Contracted dual of it, present an optimal algorithms to draw them and discuss the applications and optimality of the algorithms.
Polar Diagram,Near Pole Polar Diagram,NPPD,Voronoi Diagram,Computational Geometry,Graph Theory
http://miscj.aut.ac.ir/article_181.html
http://miscj.aut.ac.ir/article_181_734a8ce7a7f7162cb4d0f0781e3ea368.pdf
Amirkabir University of Technology
AUT Journal of Modeling and Simulation
2588-2953
2588-2961
42
1
2010
04
01
Simulation of Position Based Visual Control and Performance Tests of 6R Robot
11
19
EN
M.
Habibnejad Korayem
A.
Habibnejad Korayem
F. S.
Heidari
10.22060/miscj.2010.183
This paper presents simulation and experimental results of position-based visual servoing control process of a 6R robot using 2 fixed cameras. This method has the ability to deal with real time changes in the relative position of the target-object with respect to robot. Also, greater accuracy and independency of servo control structure from the target pose coordinates are the additional advantages of this method. Forward and inverse kinematics of 6R robot have been simulated then simulation of image processing, object recognition and pose estimation of the end effector as well as target-object in Cartesian space and visual control of robot have been prescribed. Performance tests of the 6R robot with two cameras have been simulated. Finally, analysis of error and test data has been carried out according to ISO9283, ANSI-RIA R15.05-2 standards and statistical toolbox of MATLAB. Experimental results obtained from actual implementation of visual control and tests of 6R robot in lab are presented and used to validate simulation tests.
Position based visual system,performance,test,robot,Simulation
http://miscj.aut.ac.ir/article_183.html
http://miscj.aut.ac.ir/article_183_230b298300feed818e6a7410170d10b7.pdf
Amirkabir University of Technology
AUT Journal of Modeling and Simulation
2588-2953
2588-2961
42
1
2010
04
01
Markovian Delay Prediction-Based Control of Networked Systems
21
28
EN
Behrooz
Rahmani
Amir H.
D.Markaziii
10.22060/miscj.2010.185
A new Markov-based method for real time prediction of network transmission time delays is introduced. The method considers a Multi-Layer Perceptron (MLP) neural model for the transmission network, where the number of neurons in the input layer is minimized so that the required calculations are reduced and the method can be implemented in the real-time. For this purpose, the Markov process order is estimated offline, using pr-recorded network time delay history. Unlike most of the previously existing methods, the proposed approach is both accurate and fast enough for a real time implementation. Using such a scheme for real-time estimation of the upcoming time delays, a variable state feedback gain control scheme is also proposed and applied to the predicted discretized model of the plant. The proposed approach is shown, through well-known benchmark problems, to be both accurate and fast enough for a real time implementation.
neural network,Delay Prediction,Entropy,Markov Order Estimation,Networked Control Systems (NCS),Variable Controller Design
http://miscj.aut.ac.ir/article_185.html
http://miscj.aut.ac.ir/article_185_33f2a5d16edc3bd2f66996f56e0e0a9a.pdf
Amirkabir University of Technology
AUT Journal of Modeling and Simulation
2588-2953
2588-2961
42
1
2010
04
01
Mechanism of Improvement of Formability in Pulsating Hydroforming of T-shape Tubes
29
35
EN
M.
Loh-Mousavii
M.
Bakhshi-Jooybariii
K.
Moriiii
10.22060/miscj.2010.188
In this paper, the mechanism of improvement of formability in pulsating hydroforming of T-shape tubes is investigated by the finite element simulation and experiment. It is shown that local thinning was prevented by oscillating the internal pressure, because the protrusion is formed gradually by the prevention of sharp bulging. In the hydroforming, for the pulsating pressure, several steps occur in variations in wall thickness, and thus, the thickness of the tube increases; whereas, for the peak pressure, the thickness is reduced continuously. Moreover, the effects of the amplitude and the number of cycles of pressure per unit punch, the stroke on formability and the corner filling are examined. It is shown that the small number of cycles of pressure and large amplitudes improve the formability; whereas, a large number of cycles of pressure and small amplitudes increase the die corner filling and shape accuracy as well.
Tube Hydroforming,Pulsating hydroforming,T-shape tubes,FE Simulation,Tube formability
http://miscj.aut.ac.ir/article_188.html
http://miscj.aut.ac.ir/article_188_3126427c194dfb6773afdf66e5c17435.pdf
Amirkabir University of Technology
AUT Journal of Modeling and Simulation
2588-2953
2588-2961
42
1
2010
04
01
A Theoretical and Experimental Study of Failure Maps of Sandwich Beams with Composite Skins and Honeycomb Core
37
47
EN
M.
Sadighi
A. A.
Dehkordi
R.
Khodambashi
10.22060/miscj.2010.193
Failure maps of sandwich panels such as beam, plate and shell are of great importance in designing such structures. In this paper, failure maps of sandwich beams with composite skin and honeycomb core are obtained. The effect of transverse shear in skins and core and the effect of double walls of honeycomb core have been taken into account. Shear deformation of skins and core are assumed to be linear. By minimizing the potential energy equation, the shear deformation coefficients of core and skins are obtained. Axial stresses in skins and core are obtained in terms of these coefficients. Core is assumed to have orthotropic properties. Three point bending tests have been performed on some sandwich beam specimens. It is found that specimens for which failure load and its corresponding failure mode lie away from the boundary lines in failure map, there is a little difference between failure loads obtained from theories and experiments but this difference is more significant near the boundary lines due to combination of failure modes. In the case of transverse ribbon direction, the theoretical and experimental results are closer.
Sandwich beam,failure maps,Honeycomb,composite skins and transverse shear stress
http://miscj.aut.ac.ir/article_193.html
http://miscj.aut.ac.ir/article_193_48d39b276be5e9893aab9402319de84e.pdf
Amirkabir University of Technology
AUT Journal of Modeling and Simulation
2588-2953
2588-2961
42
1
2010
04
01
Heat Transfer Characteristics of Porous Radiant Burners Using Discrete-Ordinate Method (S2-Approximation)
49
59
EN
M. M.
Keshtkari
S. A
. Gandjalikhan Nassab
10.22060/miscj.2010.195
This paper describes a theoretical study to investigate the heat transfer characteristics of porous radiant burners. A one dimensional model is used to solve the governing equations for porous medium and gas flow before the premixed flame to the exhaust gas. Combustion in the porous medium is modeled as a spatially dependent heat generation zone. The homogeneous porous media, in addition to its convective heat exchange with the gas, may absorb, emit and scatter thermal radiation. The radiation effect in the gas flow is neglected but the conductive heat transfer is considered. In order to analyze the thermal characteristics of porous burners, the coupled energy equations for the gas and porous medium based on the discrete ordinate method are solved numerically and the effect of various parameters on the performance of porous radiant burners are examined. Comparison between the present results with those obtained by other investigators shows a good agreement.
porous radiant burners,discrete ordinate method,radiative transfer,thermal characteristics
http://miscj.aut.ac.ir/article_195.html
http://miscj.aut.ac.ir/article_195_0ddf39992cfbf685a887f75514c395a4.pdf
Amirkabir University of Technology
AUT Journal of Modeling and Simulation
2588-2953
2588-2961
42
1
2010
04
01
Effects of Influence Parameters on Color Formation in Glucose Syrups during Storage
57
61
EN
Ahmadreza
Raisii
Abdolreza
Aroujalianii
10.22060/miscj.2010.196
Effects of pH, temperature, and syrup concentration on color formation in glucose syrups were studied and the shelf life of syrups under various conditions was estimated. Temperatures of 5, 25, and 45 ºC, pH values of 4, 5, and 6 as well as concentrations of 30, 40, 50, 60, 70, and 80 ºBrix were examined. After 26 weeks no significant color changes were observed at 5 ºC. At 45 ºC, color formation rate was highest and after 2 weeks color changes were visible, and at 15th week syrup color was completely brown. At 25 ºC, color formation rate was low and at week 18 color changes were visible. At pH 5, rate of browning was lower than at other pH values. Increasing the syrup concentration up to 70 ºBrix enhanced the color formation rate but higher concentrations decreased the color formation rate. The kinetics of color formation was studied and rate constants and activation energies were calculated.
Glucose syrups,Browning,Maillard reaction,Reaction kinetic,Shelf life
http://miscj.aut.ac.ir/article_196.html
http://miscj.aut.ac.ir/article_196_b3f8a66e5087bcc7e86191699d05d111.pdf