Sharif University of Technology
Scientia Iranica
1026-3098
2345-3605
25
3
2018
06
01
Experimental assessment of the redistribution of 3-D residual stresses during early fatigue at split-sleeve cold expanded reamed A/C fastener holes
1153
1168
EN
A.T.
ÖZDEMİR
Department of Materials Metallurgy Engineering, Faculty of Technology, Gazi University, Ankara, Turkey
10.24200/sci.2017.4340
Cold expansion is an effective technique of inducing favorable compressive residual stresses around fastener holes essentially vital for improving fatigue performances of aircrafts. The benefit is caused by the magnitude and distribution of the compressive stress field. Stress gradients are entirely contingent on type of the cold expansion, local geometry of the hole and characteristics of the metallic structure. During cyclic loading however, initial residual stresses do not remain stable. In the present work, specimens with 4% split-sleeve cold expanded and reamed holes were cycled at the fatigue limit for short periods. Recent method of Combined Step Drilling-Fourier Series Solution <em>‘ATÖzdemir Method’</em> was employed to appraise the continual redistributions of residual hoop stresses at the side of the hole subjected to cyclic load. Some results were compared with that of diffraction methods and Artificial Neural Network (ANN) modeling where, close similarities in stress distributions were confirmed. It is clear that during early fatigue, material nearby the hole is dynamically hardening; in response compressive residual stresses along the bore are gradually increasing till the onset of cracking. Short fatigue cracks mostly initiate from the mandrel entrance side, where subsequently residual hoop stresses begin to relax considerably.
Fastener holes,Cold expansion,Residual stress,Fatigue
http://scientiairanica.sharif.edu/article_4340.html
http://scientiairanica.sharif.edu/article_4340_447febae68e6c421ea591ef9d4c79ff6.pdf
Sharif University of Technology
Scientia Iranica
1026-3098
2345-3605
25
3
2018
06
01
Tribological behavior of refined, bleached and deodorized palm kernel as an alternative lubricant
1169
1178
EN
A.N.
Farhanah
Faculty of Mechanical Engineering, Universiti Teknologi Malaysia, 81310 UTM Johor Bahru, Johor, Malaysia
S.
Syahrullail
Faculty of Mechanical Engineering, Universiti Teknologi Malaysia, 81310 UTM Johor Bahru, Johor, Malaysia
syahruls@fkm.utm.my
10.24200/sci.2017.4339
The effects of zinc dialkyl dithiophosphate (ZDDP) concentration on tribological behavior of refined, bleached and deodorized (RBD) palm kernel were analyzed using a pin-on-disk tribotester. RBD palm kernel was selected as base lubricant due to its availability, low price, renewability and environmental friendly. Commercial mineral oil (SAE 40) was used for comparison. The tests were performed at 2.5 m/s of sliding speed under 9.8 N applied load for 60 minutes and temperature at 25 ( 2 ). Worn surface of the pin was measured by optical microscope to understand the wear mechanism involved. Experimental results showed that the addition of 5wt% of ZDDP has reduced the coefficient of friction to 21% compared with SAE 40. However, the anti-wear property was still lesser, approximately at 23%. Besides, the tribological behavior of RBD palm kernel was improved with ZDDP additive concentration above 1wt% where the best performance was at 5wt%. At this concentration level, ZDDP additive was able to protect the surface against wear and oxidation, and at the same time reduces coefficient of friction, wear rate and surface roughness values.
ZDDP,pin-on-disk,RBD palm kernel,friction,Wear,surface roughness
http://scientiairanica.sharif.edu/article_4339.html
http://scientiairanica.sharif.edu/article_4339_11e72d289341da847906c642380771fb.pdf
Sharif University of Technology
Scientia Iranica
1026-3098
2345-3605
25
3
2018
06
01
Vibration analysis of FGM rings using a newly designed cylindrical superelement
1179
1188
EN
Alireza
Fatan
Center of Excellence in Design, Robotics and Automation (CEDRA), School of Mechanical Engineering, Sharif University of Technology, Azadi Ave, Tehran, Iran
M.T.
Ahmadian
Center of Excellence in Design, Robotics and Automation (CEDRA), School of Mechanical Engineering, Sharif University of Technology, Azadi Ave, Tehran, Iran
ahmadian@sharif.ir
10.24200/sci.2017.4338
Rings are widely used in mechanical equipment and their fitness may damage under severe vibration. In these structures functionally graded rings can be used to optimize the resistance, energy consumption and better fitness. Due to their complexity, finite element analysis may be implemented using special elements. Enhancement of accuracy and minimization of time consumption play an important role in the analysis of these rings.<br /> In this study a new cylindrical superelement for the FGM rings is designed and implemented for the vibration analysis of the rings. The power-law distribution is used for modeling of the FGM rings in the thickness direction. Natural frequencies and mode shapes are obtained and results are compared with simple cases obtained from analytical solution and conventional elements. Findings indicate with a few newly designed superelements, comparable results for simple cases in the reported literature can be achieved.
Vibration analysis,Ring,FGM,Cylindrical Superelement,FEM
http://scientiairanica.sharif.edu/article_4338.html
http://scientiairanica.sharif.edu/article_4338_14a15fde43fc739c42bdec4c8499f3e1.pdf
Sharif University of Technology
Scientia Iranica
1026-3098
2345-3605
25
3
2018
06
01
Combination of projection and Galerkin finite element methods to solve the problem of free convection in enclosures with complex geometries
1189
1196
EN
Gholamreza
Zendehbudi
Mechanical Engineering Department, Yasouj university, Yasouj, Iran.
endehbudi@yu.ac.ir
10.24200/sci.2017.4332
In the present work, a numerical method to solve the problem of free convec-<br />tion in enclosures with complex geometries is developed. This development is<br />executed by the combination of projection and Galerkin nite element methods.<br />Nine-node (quadratic) quadrilateral elements are used to generate the grid for<br />the eld of the problem. The results show that the convergence of this method<br />is acceptable, while there is no necessity to use upwind schemes. Increasing<br />the numbers of nodes and decreasing the time increment yield a more accurate<br />solution. The advantages of this numerical method are the ability to model any<br />complex geometry and no necessity to use upwind schemes.
free convection,enclosures with complex geometries,galerkin method,Finite Element Method,projection method
http://scientiairanica.sharif.edu/article_4332.html
http://scientiairanica.sharif.edu/article_4332_91cc15cbf7fac62fd42d1c641a21ad8d.pdf
Sharif University of Technology
Scientia Iranica
1026-3098
2345-3605
25
3
2018
06
01
Clinical Interventions of Social Humanoid Robots in the Treatment of a Set of High- and Low-Functioning Autistic Iranian Twins
1197
1214
EN
Alireza
Taheri
Social & Cognitive Robotics Laboratory
Center of Excellence in Design, Robotics and Automation (CEDRA)
Sharif University of Technology, Tehran, Iran
taheri@mech.sharif.edu
Ali
Meghdari
0000-0001-6009-3825
Social & Cognitive Robotics Laboratory
Center of Excellence in Design, Robotics and Automation (CEDRA)
Sharif University of Technology, Tehran, Iran
meghdari@sharif.edu
Minoo
Alemi
Social & Cognitive Robotics Laboratory
Center of Excellence in Design, Robotics and Automation (CEDRA)
Sharif University of Technology, Tehran, Iran
alemi@sharif.edu
Hamidreza
Pouretemad
Institute for Cognitive and Brain Sciences (ICBS), Shahid Beheshti University, Tehran, Iran
h-pouretemad@sbu.ac.ir
10.24200/sci.2017.4337
In this paper, the robot-assisted interventions for a pair of fraternal twins with autism, one of whom is high-functioning and the other low-functioning is presented. Since many genetic and environmental factors were the same for both participants, the effect of individual and group robotic games on these two children with high- and low-functioning autism were compared. The results indicated improvement in joint attention skills for both subjects. It was further observed that robot group games had the potential to improve social skills in the subject with high-functioning autism; and lower the amount of stereotyped and detrimental behaviors in the participant with low-functioning autism. Both participant’s communication with each other improved, and their mother claimed she observed her children playing a meaningful game together at home for the first time since their birth.
Social robots,High- and low-functioning autism,Twins with autism,Imitation,Social skills,Joint Attention
http://scientiairanica.sharif.edu/article_4337.html
http://scientiairanica.sharif.edu/article_4337_af86c082f82f4d0c005b20e8c09983b9.pdf
Sharif University of Technology
Scientia Iranica
1026-3098
2345-3605
25
3
2018
06
01
Unsteady double-diffusive natural convection with Soret and Dufour effects inside a two-sided lid-driven skewed enclosure in the presence of applied magnetic field
1215
1235
EN
Omid
Ghaffarpasand
Department of Physics, University of Isfahan, Isfahan 81746, Iran
o.ghaffarpasand@gmail.com
10.24200/sci.2017.4497
This article describes the heat and mass transfer as well as the entropy generation in an unsteady double-diffusive natural convection in the presence of an external magnetic eld, Soret and Dufour eects. The analysis uses a two- dimensional skewed enclosure, where the inclined walls make a skew angle with x-axis. The governing equations in the physical domain are transformed into an orthogonal computational domain by co-ordinate transformations, and then are solved using a nite volume method based on SIMPLE algorithm. The computations are carried out in the six skewed enclosures with skew angles = 15, 30, 45, 60, 75, and 90, for a wide range of the Hartman number, Lewis number, buoyancy ratio, and Dufour coecient, while Soret coecient is kept constant at 0.25 in most of the study. Results show that the fluid flow, heat and mass transfer, as well as the entropy generation are sensible to some extent to the skew angle variation. Meanwhile, the Lewis number and buoyancy ratio have an aiding and opposing action, respectively, on suppression effect of Lorentz force against convective heat and mass transfer. It is also shown that the average entropy generation is an increasing function of Lewis number, buoyancy ratio, and Dufour coecient, while its a decreasing function of Hartman number.
Double-diffusive natural convection,Soret and Dufour effects,Lewis number,Buoyancy ratio,Skewed cavity
http://scientiairanica.sharif.edu/article_4497.html
http://scientiairanica.sharif.edu/article_4497_be21d8e8b3147189f15629f2dc54dacf.pdf
Sharif University of Technology
Scientia Iranica
1026-3098
2345-3605
25
3
2018
06
01
A new approach to thermo- Fluid behavior through porous layer of heat pipes
1236
1242
EN
A.
Nouri-Borujerdi
School of Mechanical Engineering, Sharif University of Technology, Tehran, Iran
anouri@sharif.edu
10.24200/sci.2017.4526
This paper developed a new mathematical model to investigate the heat transfer as well as wick thickness of a heat pipe. The model was set up by conservative equations of continuity, momentum and energy in the thermal boundary layer. Using the similarity variable, the governing equations have been changed to a set of ordinary differential equations and they were solved numerically by the forth order Runge-Kutta method. The flow variables such as velocity components, wick thickness and Nusselt number were obtained. The results show that the Nusselt number is proportional to the root square root of the Darcy-modified Rayleigh number and that the distance from the edge of the condenser surface. Furthermore, the thickness of the wick material depends on the Jakob number and proportional to the heat transfer between the wall and the liquid film.
Annular condensation flow,Heat pipes,Heat Transfer,Numerical method,porous media
http://scientiairanica.sharif.edu/article_4526.html
http://scientiairanica.sharif.edu/article_4526_0e1157e0eeaa3ce2231ca52b0bceae50.pdf
Sharif University of Technology
Scientia Iranica
1026-3098
2345-3605
25
3
2018
06
01
Effect of thermal radiation on magneto-nanofluids free convective flow over an ac-celerated moving ramped temperature plate
1243
1257
EN
S. M.
Hussain
Department of Mathematics, O.P. Jindal university, Raigarh (C.G.), INDIA
hussain.modassir@yahoo.com
J.
Jain
Department of Applied Mathematics, Government Engineering College, Bastar (C.G.), INDIA
G. S.
Seth
Department of Applied Mathematics, Indian Institute of Technology (ISM), Dhanbad, INDIA
M. M.
Rashidi
Shanghai Key Lab of Vehicle Aerodynamics and Vehicle Thermal Management System, Tongji University, Shanghai-201804, CHINA
10.24200/sci.2017.4333
An attempt has been made to explore the effect of thermal radiation on electrically conducting, viscous and incompressible magneto-nanofluids free convective flow in the presence of an inclined magnetic field. Fluid flow is persuaded due to an accelerated movement of an infinite vertical ramped temperature plate. The water based nanofluids with the nanoparticles of alumina (Al<sub>2</sub>O<sub>3</sub>), copper (Cu) and titanium oxide (TiO<sub>2</sub>) have been accounted. In order to model the problem mathematically, the model of nanoparticle volume fraction has been employed. The exact solution of the mathematical model in closed form has been obtained analytically by making use of Laplace transform technique. The amalgamated form expressions are obtained for nanofluid velocity, nanofluid temperature, skin friction and Nusselt number, in both ramped and isothermal conditions. The consequence of various physical parameters affecting the nanofluid velocity and nanofluid temperature have examined by means of various graphs whereas, the numerical values of skin friction and Nusselt number have been reported by different tables. The numerical results have been compared for both ramped and isothermal conditions. It has been noticed that both the nanofluid velocity and temperature are smaller in magnitude in the case of ramped temperature plate than that of isothermal plate.
Nanofluid,Inclined magnetic field,thermal radiation,Ramped temperature
http://scientiairanica.sharif.edu/article_4333.html
http://scientiairanica.sharif.edu/article_4333_52f9371cf9fc7beadbfe37a9f4606560.pdf
Sharif University of Technology
Scientia Iranica
1026-3098
2345-3605
25
3
2018
06
01
An experimental investigation into heat transfer in milk cooling vessels
1258
1265
EN
U.
Durmaz
Department of Mechanical Engineering, Sakarya University, Sakarya, Turkey
udurmaz@sakarya.edu.tr
M.
Ozdemir
Department of Mechanical Engineering, Sakarya University, Sakarya, Turkey
H.
Pehlivan
Department of Mechanical Engineering, Sakarya University, Sakarya, Turkey.
10.24200/sci.2017.4336
The raw milk is an important basic material for many food products. Fresh milk must be cooled immediately after milking to keep high quality and process ability. In this work the overall heat transfer coefficients of the milk cooling vessels used for this purpose have been studied experimentally. This study is aimed to determine the overall heat transfer coefficients of cooling vessels which have different types and capacities without the freezing and churning to avoid separation of milk's fat. Vessels are used ranged as follows: 300-500-1000-1500-1850-2000 litres for verticals and 2000-2500-3000-4000-5000-6000 litres for horizontals. It is found that the theoretical calculations are in satisfactory agreement with the experimental data. As a result of investigation, the overall heat transfer coefficient can be written as related with power intensity for horizontal vessels. It is a certain constant value for vertical ones.
Heat transfer coefficient,Agitated vessels,Milk cooling,Power intensity,Horizontal and vertical vessels
http://scientiairanica.sharif.edu/article_4336.html
http://scientiairanica.sharif.edu/article_4336_ea5f9b704f8f892710b40897f795f346.pdf
Sharif University of Technology
Scientia Iranica
1026-3098
2345-3605
25
3
2018
06
01
Artificial Neural Network Modelling for Polyethylene FSSW Parameters
1266
1271
EN
Memduh
KURTULMUŞ
0000-0001-6525-232X
Marmara University, School of Applied Sciences, Istanbul 34722, Turkey
memduhk@marmara.edu.tr
Alper
Kiraz
0000-0001-7067-1473
Industrial Engineering, Engineering Faculty, Industrial Engineering, Sakarya University, Sakarya, Turkey
kiraz@sakarya.edu.tr
10.24200/sci.2018.50030.1473
In friction stir spot welding (FSSW) process the welding parameters (the tool rotational speed, the tool plunge depth and the stirring time) effect the nugget formation in high density polyethylene (HDPE) sheets. The size and the microstructure of the nugget determine the resistance of the joint to outer forces. The optimization of these parameters are vital to obtain high quality welds. Feed forward back propagation artificial neural network models are developed for the optimization of the FSSW parameters for HDPE sheets. Input variables of these models are the tool rotation speed (rpm), the plunge depth (mm) and the stirring time (s) affect to lap-shear fracture load (N) output. Prediction performance of 6 models in different specifications are compared. These models differ in terms of the training dataset used (80%-100%) and the number of neurons (5-10-20) in hidden layer. Best prediction performances are obtained with using 20 neurons in hidden layer in both training dataset. There is a good agreement between developed models’ predictions and the experimental data.
Friction stir spot welding (FSSW),high density polyethylene (HDPE),Artificial Neural Networks,optimization
http://scientiairanica.sharif.edu/article_20525.html
http://scientiairanica.sharif.edu/article_20525_ea65c24093f5fef399bdd190cc434f29.pdf
Sharif University of Technology
Scientia Iranica
1026-3098
2345-3605
25
3
2018
06
01
Impact of Information Technology on Business Performance: Integrated Structural Equation Modeling and Artificial Neural Network Approach
1272
1280
EN
Hasan
ŞAHİN
Dumlupinar University, Simav Vocational School, 43500, Simav- Kütahya, Turkey
Bayram
TOPAL
Sakarya University, Faculty of Management, Serdivan-Sakarya, Turkey
10.24200/sci.2018.20526
In today's globalizing world, which is also called the information age, information and information technologies are becoming increasingly important for businesses, and they have become an indispensable part of economic and social life. Nowadays, it is impossible to think about a business that is far from information technology, and also it is important not only to find information but also to find the fastest and highly reliable information. The important thing is to use information technologies effectively and efficiently. Therefore, it is expected that the effective usage of information technology will have significant positive effects on business performance. The aim of this study is to examine and analyze the impact of the intensive usage of information technologies on business performance in the supply chain process. A sequential, multi-method approach integrating both structural equation modeling (SEM) and neural network analysis was employed in this research. The information technology usage performance network was formed by using the SEM model, and the ANN model was used to predict a relationship between information technology usage levels and business performance by using these network outputs. Furthermore, the validity and reliability tests of the relevant model data were performed.
Business performance,information technology,information quality,structural equation model,Neural network
http://scientiairanica.sharif.edu/article_20526.html
http://scientiairanica.sharif.edu/article_20526_4b6e7c5435e723c2d391650fd620a75f.pdf
Sharif University of Technology
Scientia Iranica
1026-3098
2345-3605
25
3
2018
06
01
Comparison of Nonlinear Filtering Techniques for Inertial Sensors Error Identification in INS/GPS Integration
1281
1295
EN
Samira
Kaviani
Department of Mechanical Engineering, Sharif University of Technology
PO. Box 11365-9567, Iran
Hassan
Salarieh
Department of Mechanical Engineering, Sharif University of Technology
PO. Box 11365-9567, Iran
salarieh@sharif.edu
Aria
Alasty
Department of Mechanical Engineering, Sharif University of Technology
PO. Box 11365-9567, Iran
aalasty@sharif.edu
Mohammad
Abediny
Department of Mechanical Engineering, Sharif University of Technology
PO. Box 11365-9567, Iran
10.24200/sci.2017.4328
<strong>Nonlinear filtering techniques are used to fuse the global positioning system (GPS) and the inertial navigation system (INS) together to provide a robust and reliable navigation system with a performance superior to that of either INS and GPS alone. Prominent nonlinear estimators in this field are the Kalman Filters (KF) and Particle Filters (PF). The main objective of this research is the comparative study of the well-established filtering methods of EKF, UKF and the PF based on EKF and UKF in INS-GPS integrated navigation system. Different features of INS-GPS integrated navigation methods in the state estimation, bias estimation and bias/scale factor estimation are investigated by using these four filtering algorithms. Both ground-vehicle experimental test and flight simulation test have been utilized to evaluate the filters performance</strong>
Extended Kalman Filter (EKF),Unscented Kalman Filter (UKF),Extended Particle Filter (EPF),Unscented Particle Filter (UPF)
http://scientiairanica.sharif.edu/article_4328.html
http://scientiairanica.sharif.edu/article_4328_f86aea8d98c12620e90fa5f30bc35077.pdf
Sharif University of Technology
Scientia Iranica
1026-3098
2345-3605
25
3
2018
06
01
A New Algorithm to Solve Sinusoidal Steady State Maxwell's Equations on Unstructured Grids
1296
1302
EN
Sajjad
Azimi
Mechanical Engineering Departement, Sharif University of
Technology, Tehran, Iran
Mohammad Said
Saidi
Mechanical Engineering Departement, Sharif University of
Technology, Tehran, Iran
10.24200/sci.2017.4334
A new approach for numerical solution of sinusoidal steady state<br />Maxwell's equations is developed. This approach is based on Yee's<br />method, and can be applied on unstructured grids. A case problem<br />with available analytical solution is solved by the method and the<br />results show a good agreement with analytical solution. This method<br />can be improved to be applicable for general unsteady problems.
Maxwell's equations,numerical solution,un- structured grid,Yee's method,enclosed volume
http://scientiairanica.sharif.edu/article_4334.html
http://scientiairanica.sharif.edu/article_4334_447f3db161acd7f900a2ff1441c68ffb.pdf
Sharif University of Technology
Scientia Iranica
1026-3098
2345-3605
25
3
2018
06
01
A note on the critical gap of bubble coalescence during foaming process: A diffuse-interface modeling
1303
1311
EN
Ehsan
Amiri Rad
Hakim Sabzevari University, Iran
10.24200/sci.2017.4335
Bubble coalescence is an important stage of foaming process. A goal of foaming is to produce numerous, uniform-size bubbles. Therefore suppression of bubble coalescence is desirable during foaming process. For stationary bubbles, if their distance be less than a critical gap they will coalesce. Actually in this case, attractive forces attract the outer surfaces to touch each other and form a growing gas bridge which merge the bubbles finally. For bigger distance, the attractive forces cannot make a bridge and coalescence will not happen. In this study the dynamics of bubble coalescence is modeled using a diffuse-interface LBM. Then critical gap of bubble coalescence is defined as the maximum distance between the stationary bubbles where the coalescence will happen. Sensibility of critical gap is obtained with respect to critical properties of material, bubble size, viscosity of gas and liquid, density ratio, surface tension, temperature and interface thickness. The results show that, interface thickness is the only factor that controls the critical gap. In the other word, in the case of stationary bubbles, by a precise estimation of interface thickness, the coalescence can be predicted. Critical gap is a useful parameter in foaming where the maximum number of bubbles is desirable.
Bubble,Coalescence,Critical gap,Foaming,Lattice Boltzmann
http://scientiairanica.sharif.edu/article_4335.html
http://scientiairanica.sharif.edu/article_4335_8184ab41801e31c621ef9725248042be.pdf
Sharif University of Technology
Scientia Iranica
1026-3098
2345-3605
25
3
2018
06
01
A Comparison of Some Methods for Structural Damage Detection
1312
1322
EN
Kamal
Rezvani
Department, Faculty of New Sciences & Technologies, University of Tehran, North Kargar, Tehran, Iran
Maia
N. M. M.
department of Instituto Superior Técnico, Universidade de Lisboa, Av. Rovisco Pais Lisboa, Portugal
Mohammad H.
Sabour
Faculty of New Sciences & Technologies, University of Tehran, North Kargar, Tehran, Iran
10.24200/sci.2017.4494
In principal, a proper analysis of the dynamic response of a structure can provide general indicators of its operational conditions. When the dynamic response changes due to a variation of the physical properties of a structure, then one may conclude that some kind of damages has occurred. This paper presents investigation of the robustness and comparison of four simple methodologies to both identify and quantify the damages in structures, based on the use of Frequency Response Functions (FRF) signals, Principal Component Analysis technique (PCA) and Transmissibility. A steel beam with constant rectangular cross-section is used to compare the proposed approaches. At first, nine damaged scenarios are created and for each of them numerical examples are discussed; a database of FRFs is measured using modal testing. Then, PCA theory is applied to the FRF matrix and global damage detection and quantification indices are defined by using the first 3 Principal Components; Hotelling's T-squared distribution is also applied and by using transmissibility two other indicators, Transmissibility Damage Indicator and Weighted Damage Indicator, are computed for the assessment of damage. The reported examples show that all proposed methods are able to detect and quantify damages at the initial stage.
structural health monitoring,Damage detection,FRF Curvatures,Modal Testing,Damage indicator
http://scientiairanica.sharif.edu/article_4494.html
http://scientiairanica.sharif.edu/article_4494_62f3f92dfc5d36e9f4f23657906e9087.pdf