eng
Sharif University of Technology
Scientia Iranica
1026-3098
2345-3605
2016-08-01
23
4
1719
1730
10.24200/sci.2016.3920
3920
Modeling and optimizing of PV–wind–diesel hybrid systems for electrification of remote villages in Iran
Majid Sedghi
majid.sedghi@me.iut.ac.ir
1
Siamak Kazemzadeh Hannani
hannani@sharif.edu
2
Mech. Eng
Mech. Eng
The main objective of this work is to provide an electric supply to remote Iranian villages that have no access to electricity grid using a stand-alone hybrid system. The hybrid systems considered in this study consist of a photovoltaic array, wind turbine, diesel generator and battery storage. Measured wind speed data was used for a wind turbine energy production model. The hybrid system optimized the electricity supply of villages with 6, 14, 20, 40 and 60 households in Bojnord, Moorchekhort, Kish, Langroud, Khash and Meshkinshahr. The main purpose of this optimization is to find an economical system configuration that is able to fulfill the energy requirements of a given load distribution while considering Iran’s current economy and cost. The optimized results for studied cases have been analyzed and implementation feasibility is discussed
http://scientiairanica.sharif.edu/article_3920_a7c25e5bf3dfede9b8b8a9a269dfcaa3.pdf
Photovoltaic
Wind Turbine
Diesel generator
Economic optimization
Iranian villages
eng
Sharif University of Technology
Scientia Iranica
1026-3098
2345-3605
2016-08-01
23
4
1731
1740
10.24200/sci.2016.3921
3921
Eeffcts of hypertension on Intima-Media Thickness (IMT); application to a human carotid artery
S.A. Mirbagheri
1
M.S. Saidi
dzwgnvmz@scientiaunknown.non
2
S. Sohrabi
3
B. Firoozabadi
4
M.H. Banazadeh
5
School of Mechanical Engineering, Sharif University of Technology, Tehran, Iran.
School of Mechanical Engineering, Sharif University of Technology, Tehran, Iran.
School of Mechanical Engineering, Sharif University of Technology, Tehran, Iran.
School of Mechanical Engineering, Sharif University of Technology, Tehran, Iran.
School of Mechanical Engineering, Sharif University of Technology, Tehran, Iran.
A vast number of deaths in the world have been attributed to atherosclerosis. The prominent aim of this study is proposing an accurate and simple model to investigate the process of arterial wall thickening. In order to investigate LDL (Low Density Lipoprotein) accumulation in arterial wall, a four layer model for arterial wall consisting of endothelium, intima, IEL, and media is presented. All layers are treated as homogenous porous media. This model has been solved both numerically and analytically. Obtained accumulated LDL in the intima is used to calculate oxidized LDL flux. Also, the presented model and clinical data are used to prepare the growth model for arterial wall. Furthermore, the eect of hypertension on ltration velocity and rate of wall thickening has been studied which is in consistent with experimental data. Results show that the average rates of intima thickening of hypertensive patients with 120 mmHg and 160 mmHg transmural pressure are 5.87 m/year and 6.12 m/year, respectively. This rate for healthy subjects with 70 mmHg transmural pressure has been calculated 4.5 m/year. Finally, this model is applied to a carotid artery, and the maximum intimal growth rate for people with 70 mmHg, 120 mmHg and 160 mmHg transmural pressure is calculated 4.68 m/year, 6.28 m/year, and 6.67 m/year, respectively.
http://scientiairanica.sharif.edu/article_3921_66a506a426e42642db9b08ec4566fa13.pdf
Atherosclerosis
Mass transport
LDL
CFD
Intima
Carotid bifurcation
eng
Sharif University of Technology
Scientia Iranica
1026-3098
2345-3605
2016-08-01
23
4
1741
1752
10.24200/sci.2016.3922
3922
Vibration controlof tapered magnetostrictive plate considering shear correction factor
A. Ghorbanpour Arani
aghorban@kashanu.ac.ir
1
Z. Khoddami Maraghi
2
H. Khani Arani
3
Department of solid mechanics, Faculty of Mechanical Engineering, University of Kashan, Kashan, I. R. Iran
Department of solid mechanics, Faculty of Mechanical Engineering, University of Kashan, Kashan, I. R. Iran
Department of solid mechanics, Faculty of Mechanical Engineering, University of Kashan, Kashan, I. R. Iran
In this research, dynamic response of tapered plate made of MsM (magnetostrictive material) is studied for the first time. First order shear deformation theory (FSDT) is used to derive the governing equations of tapered MsP (magnetostrictive plate) while the thickness varies linearly. To enhance the accuracy of the results, shear correction factor is considered and a feedback control system is utilized to investigate the effects of magnetic field on MsP. The five equations of motion that obtained by Hamilton’s principle are solved using differential quadrature method (DQM) and compared by those available in the literature. Results indicate the effect of various parameters such as aspect ratio, thickness ratio, taper ratio, boundary conditions and the controller effect of velocity feedback gain on the frequency of MsP. These finding can be used to active noise and vibration cancellation systems in many smart structures.
http://scientiairanica.sharif.edu/article_3922_46b1fef9d90f30164a339b171882eef9.pdf
Free vibration
Magnetostrictive rectangular plate
Taper ratio
Feedback control system
differential quadrature method
eng
Sharif University of Technology
Scientia Iranica
1026-3098
2345-3605
2016-08-01
23
4
1753
1766
10.24200/sci.2016.3923
3923
Experimental and 3D CFD investigation on energy separation inside a convergent vortex tube air separator
Seyed Ehsan Rafiee
rafieeehsan@ymail.com
1
M. M. Sadeghiazad
2
Assistant Professor
Associate Professor
The vortex tube air separator is an invaluable tool which has the ability to separate a high pressure fluid into the cold and hot fluid streams. The hot tube is a main part of the vortex tube which the energy separation procedure happens along this part. This research has been done to analyze the effect of the convergent angle and cold orifice diameter on the thermal efficiency of a convergent vortex tube. The convergent hot tubeangleis varied over the range of 1 to 9deg. The consideration of the main angle effect, denotes that the highest thermal ability could be achieved at β=5deg. Experiments denoted that both cooling capability and heating effectiveness reach the highest magnitudes when the DCold is around 9mm. After these two stages; the optimized convergent vortex tube was capable of decreasing and rising air temperatures at the cold and the hot sides up to 9.05K(42.89%) and 10.48K(44.74%) respectively. A computational fluid dynamics model was employed to predict the performance of the convergent vortex tube. The numerical investigation was done by full 3D steady state CFD-simulation using FLUENT6.3.26. The results show that the agreement between computation predictions and laboratory measurements is fairly good.
http://scientiairanica.sharif.edu/article_3923_2a3526d3093fda0a991353b2ce177db2.pdf
Experimental approach
Numerical computation
Convergent hot tube
Air separator
Convergent angle
Cold orifice diameter
eng
Sharif University of Technology
Scientia Iranica
1026-3098
2345-3605
2016-08-01
23
4
1767
1776
10.24200/sci.2016.3924
3924
The Aerodynamic and Dynamic Analysis ofThree Common 4.5mm Caliber Pellets in a Transonic Flow
Mehdi Rafeie
mehdi.rafeie@gmail.com
1
Ali Reza Teymourtash
teymourtash@um.ac.ir
2
دانشگاه فردوسی مشهد
دانشگاه فردوسی مشهد
In this paper, a numerical solution of the Navier-Stokes equations has been considered using Jameson method in a transonic flow over three air gun pellets. Furthermore, obtained aerodynamic results have been used in order to analyze the trajectories of the projectiles dynamically. The considered pellets have the same caliber of 4.5mm, but different nose shapes. The first pellet is a wadcutter, while the two other ones are a sharp pointed and a domed head respectively. These pellets have been geometrically simulated by means of a precise photography and a digitizer software application for the accurate determination of the plots and grid generation purposes. The aerodynamic results contain the streamlines, drag and pressure coefficients as well as pressure and Mach contours. These results demonstrate how drag coefficient changes versus the Mach number of the free stream flow which is a key point for the governing equations of the projectile motion. Dynamic results, which consist of trajectory and the Mach reduction diagrams of the pellets in various Mach numbers, have been acquired and compared in various Mach numbers. Relying on these analyses, from both aerodynamic and dynamic points of view, the third pellet in a variety range of Mach numbers is the most dominant projectile; however, the selection of superior pellet between the first and the second one strongly depends on considered Mach numbers at which the pellet travels its effective range of fly. The first pellet has a better fly than the second one at low Mach numbers, while at Mach numbers close to 1.0 and more, the preferable pellet is the second one.
http://scientiairanica.sharif.edu/article_3924_a9d6fcc8f62a7f6128470ef369811175.pdf
Navier-Stokes equations
Jameson method
transonic flow
Dynamic analysis
Air gun pellet
eng
Sharif University of Technology
Scientia Iranica
1026-3098
2345-3605
2016-08-01
23
4
1777
1786
10.24200/sci.2016.3925
3925
Experimental estimation heat flux and heat transfer coefficient by using inverse methods
S.D. Farahani
1
A.R. Najafi
2
F. Kowsary
htdxdixy@scientiaunknown.non
3
M. Ashjaee
4
Department of Mechanical Engineering, University College of Engineering, University of Tehran, Tehran, P.O. Box 11155-4563, Iran.
Department of Mechanical Engineering, University College of Engineering, University of Tehran, Tehran, P.O. Box 11155-4563, Iran.
Department of Mechanical Engineering, University College of Engineering, University of Tehran, Tehran, P.O. Box 11155-4563, Iran.
Department of Mechanical Engineering, University College of Engineering, University of Tehran, Tehran, P.O. Box 11155-4563, Iran.
The purpose of this paper is to present experimental applications of the inverse heat transfer methods (conjugate gradient method and sequential method). Three experiments are designed to estimate the heat ux and the heat transfer coecients. In the third experiment, convective heat transfer coecient is estimated directly and indirectly. In direct estimation, the conjugate gradient method with adjoint equation is used. The results show that inverse heat transfer methods are able to estimate the desired parameters with good accuracy in experimental state when mathematical model and boundary condition are correct and appropriate with experimental model.
http://scientiairanica.sharif.edu/article_3925_1ff95f8cdb699f3010efdbaafa7fd1f9.pdf
Inverse method
heat flux
Convective heat transfer coecient
Adjoint equation
eng
Sharif University of Technology
Scientia Iranica
1026-3098
2345-3605
2016-08-01
23
4
1787
1799
10.24200/sci.2016.3926
3926
Finite Element Formulations for Free Vibration Analysis of Isotropic and Orthotropic Plates using Two-Variable Refined Plate Theory
Jafar Rouzegar
rouzegar@sutech.ac.ir
1
Reza Abdoli Sharifpoor
2
Department of Mechanical and Aerospace Engineering, Shiraz University of Technology, Shiraz, P.O. Box 71555-313, Iran
Department of Mechanical and Aerospace Engineering, Shiraz University of Technology, Shiraz, P.O. Box 71555-313, Iran
In this paper, a finite element formulation based on two-variable refined plate theory is developed for free vibration analysis of isotropic and orthotropic plates. The two-variable refined plate theory, which can be used for both thin and thick plates, predicts parabolic variation of transverse shear stresses across the plate thickness, satisfies the zero traction condition on the plate surfaces and does not need the shear correction factor. After constructing weak form equations using the Hamilton principle for vibration formulation, a new 4-node rectangular plate element with six-degrees of freedom at each node is introduced for discretization of the domain. The natural frequencies of isotropic plates with different boundary condition and the fundamental natural frequencies of levy type orthotropic plates are obtained. Comparison of results with exact solutions and other common plate theories shows that beside the simplicity of presented finite element formulations, it presents accurate and efficient results. Also the effects of orthotropy ratio, side-to-thickness ratio and types of boundary conditions on the natural frequencies are studied.
http://scientiairanica.sharif.edu/article_3926_a5d4e7ad8b010793d81c71765e9a249f.pdf
finite element method
Free vibration
Rectangular plate element
Two-variable refined plate theory
eng
Sharif University of Technology
Scientia Iranica
1026-3098
2345-3605
2016-08-01
23
4
1800
1810
10.24200/sci.2016.3927
3927
Analysis of tool wear in ultrasonically assisted turning of -Ti-15V-3Al-3Cr-3Sn alloy
R. Muhammad
1
A. Mistry
2
S.W. Khan
3
N. Ahmed
4
A. Roy
5
V.V. Silberschmidt
6
Department of Mechanical Engineering, CECOS University of IT and Emerging Sciences, Peshawar, KPK, Pakistan.
Wolfson School of Mechanical and Manufacturing Engineering, Loughborough University, Leicestershire, LE11 3TU, UK.
Department of Civil Engineering, UET Peshawar, KPK, Pakistan.
Department of Mechanical Engineering, CECOS University of IT and Emerging Sciences, Peshawar, KPK, Pakistan.
Wolfson School of Mechanical and Manufacturing Engineering, Loughborough University, Leicestershire, LE11 3TU, UK.
Wolfson School of Mechanical and Manufacturing Engineering, Loughborough University, Leicestershire, LE11 3TU, UK.
An extremely high tool wear rate in the machining of titanium alloys (Ti alloys) is one of the major reasons limiting the use of conventional machining processes for the components made of these alloys. The machinability of a -Ti-15V-3Al-3Cr-3Sn (Ti- 15333) alloy can be signicantly improved using an advanced machining technique known as Ultrasonically Assisted Turning (UAT). The key mechanism of tool wear associated with UAT of Ti-15333 alloy is still unknown. The present study begins to address this issue by examining wear behaviour of two dierent types of cutting inserts using UAT and Conventional Turning (CT) of Ti-15333 alloy. Tool wear was measured using 3D optical microscope and the composition of the Built-Up Edge (BUE) on the worn tools was analysed with scanning electron microscopy. A robust experimental methodology was developed, which provided repeatable and statistically reliable tool wear results. The KC5510 cutting inserts demonstrated better tool-life in UAT when compared to CP-500 inserts.
http://scientiairanica.sharif.edu/article_3927_678a7b7f87d43b617b0e2bc502d9f828.pdf
Titanium alloys
Tool wear
Ultrasonically assisted turning
Cutting inserts
Conventional turning
eng
Sharif University of Technology
Scientia Iranica
1026-3098
2345-3605
2016-08-01
23
4
1811
1825
10.24200/sci.2016.3928
3928
Effects of Shock Wave/Boundary-Layer Interaction on Performance and Stability of a Mixed-Compression Inlet
Mohammad Reza Soltani
msoltani@sharif.edu
1
Abbas Daliri
abbasdaliry@gmail.com
2
Javad Sepahi Younsi
j_sepahi@yahoo.com
3
Experiments were conducted to study various kinds of shock wave/boundary layer interaction (SBLI) in an axisymmetric mixed-compression inlet. Further, some of the experimental findings were compared and verified by numerical solutions where possible. A classification of different types of SBLI relevant to the mixed-compression inlets is performed. Interactions of expelled normal shock wave/boundary-layer at subcritical and at buzz condition is investigated using Schlieren and shadowgraph flow visualization as well as unsteady pressure recordings. The data is further compared with the CFD prediction. Interactions of cowl lip reflected oblique shock and the terminal normal shock with the spike boundary-layer at both critical and supercritical operations that leads to shock trains and pseudo-shock phenomena are also studied. In this case numerical simulation results were used to illustrate the flow field. Experimental pressure recordings are used for validation and further discussion. The structure of SBLI flow in an inlet depends highly on the throttling value. For near critical throttling values, interaction of internal compression oblique shocks with boundary-layer and pseudo-shock phenomenon is dominant. Increasing the inlet back pressure pushes normal shock wave out of the inlet duct. Formation of lambda shock due to interaction of separated boundary-layer with normal shock wave is also investigated. The numerical and experimental results show that there exist different kinds of shock wave boundary-layer interactions relevant to the supersonic inlets. Each of these flow interaction phenomena has different effects on the stability and on the performance of the inlet. Interaction of terminal normal shock with internal duct boundary-layer causes pseudo-shock phenomenon that leads to increase of flow distortion and reduction of total pressure recovery. In addition interaction of normal shock wave with external cone boundary-layer causes buzz instability and degrades inlet performance.
http://scientiairanica.sharif.edu/article_3928_d66dd76159725aebb70fa5c727342e2a.pdf
Supersonic Inlet
Shock Wave/Boundary-Layer Interaction (SBLI)
Pseudo-Shock
Shock Train
Buzz
eng
Sharif University of Technology
Scientia Iranica
1026-3098
2345-3605
2016-08-01
23
4
1826
1836
10.24200/sci.2016.3929
3929
Fluid-structure interaction analysis of air flow in pulmonary alveoli during normal breathing in healthy humans
M. Monjezi
1
M.S. Saidi
dzwgnvmz@scientiaunknown.non
2
School of Mechanical Engineering, Sharif University of Technology, Tehran, Iran.
School of Mechanical Engineering, Sharif University of Technology, Tehran, Iran.
In this work, the human lung alveoli are idealized by a three dimensional honeycomb like geometry and a fluid-structure analysis is performed to study the normal breathing mechanics. In contrast to previous works in which the inlet flow rate is predened, in this model, we have applied a negative pressure on the outside surface of the alveolus which causes air to flow in and out of the alveolus. The integration of the experimental curve of breathing flow rate was used to approximate the shape of the external applied pressure. Our Fluid-Structure Interaction (FSI) model has an advantage over other literature since it addresses both the fluid dynamics and solid mechanics, simultaneously. The flow patterns conrmed that there is no circulation in the terminal alveolus. We have applied three distinct material models { linear isotropic elastic, hyperelastic, and viscoelastic in order to simulate the mechanical behavior of alveolar wall tissue using ADINA software. The hysteresis behavior of the alveolar tissue was well predicted by a compliance diagram of the viscoelastic model while this behavior is not observed in the linear elastic and hyperelastic model. The stress and strain distribution is also obtained and is found to be non-uniform.
http://scientiairanica.sharif.edu/article_3929_264d9a4a879d06b161297e8927297eea.pdf
FSI
Alveolar wall
Viscoelastic
Stream line
Stress
strain
eng
Sharif University of Technology
Scientia Iranica
1026-3098
2345-3605
2016-08-01
23
4
1837
1843
10.24200/sci.2016.3930
3930
New groundwater flow equation with its exact solution
Abdon Atangana
abdonatangana@yahoo.fr
1
Canan Ünlü
unlucanan@hotmail.com
2
Institute for Groundwater Studies, Faculty of Natural and Agricultural Sciences, University of the Free State 9300 Bloemfontein, South Africa
Department of Mathematics, Faculty of Sciences, University of Istanbul, 1293 Istanbul, Turkey
A new model of groundwater flowing within a confined aquifer was proposed using the concept of local derivative with fractional order. The derivative used in this model obeys all the properties of a local derivative and has a fractional order. The new groundwater flow equation was solved analytically via three different analytical methods. The first method is the well-known method of separation of variable. The problem with this method is the introduction of the Eigen-value that does not have physical meaning. The second method was achieved using novel integral equation called Atangana-transform and this method yields exact solution. An alternative method based on the modified Boltzmann transformation also yields to exact solution. Some numerical simulations were done to express the efficiency of the model
http://scientiairanica.sharif.edu/article_3930_95e717d5a489c4fed9cacb49d36b74fa.pdf
New groundwater equation
beta-derivative
analytical methods
simulations
eng
Sharif University of Technology
Scientia Iranica
1026-3098
2345-3605
2016-08-01
23
4
1844
1855
10.24200/sci.2016.3931
3931
Flexible Formation of Multiple Car-like Robots with respect to a Dynamic Environment
Hassan Sayyaadi
sayyaadi@sharif.edu
1
School of Mechanical Engineering, Sharif University of Technology, Azadi Avenue, Tehran 11155-9567, Iran
This paper attempts to give a perspective on decentralized formation control of multiple car-like mobile robots using local information and formation changes in a dynamic environment having several obstacles. In addition, for every mobile robot, it takes physical dimensions, mass, moment of inertia, movement constraints and saturation of actuators into account. This study makes use of Input/output feedback linearization method to control each robot. Hence, hierarchical leader follower based algorithm is employed to control the group formation. To avoid collision between robots and obstacles, and between robots each other’s, local artificial potential fields are addressed. The group can change formation with respect to obstacles in the environment. Finally, simulation results of seven individual robots formation are presented to show the performance of the proposed control system.
http://scientiairanica.sharif.edu/article_3931_50e246ee22e7473d800e122fe0530c77.pdf
Formation control
Nonholonomic
Car-like Mobile robots
Feedback Linearization