eng
Materials and Energy Research Center
International Journal of Engineering
1025-2495
1735-9244
2015-05-01
28
5
648
653
72501
Earth’s Magnetic Field for Spacecraft Attitude Control Applications (TECHNICAL NOTE)
N. Nasiri
nasirikn@my.erau.edu
1
M Navabi
sciences.edu@gmail.com
2
Physics Engineering, Embry-Riddle Aeronautical University
New Technologies Engineering, Shahid Beheshti University
In this paper the earth’s magnetic field is simulated precisely while the intensity and direction of the field are verified with one of the standard references for selected points on the earth and the results are compared with some low-order models. In another simulation, the complete model is compared with a common approximate model. The magnetic field in orbital frame is described and to employ earth’s magnetic field in spacecraft attitude control applications, it is transferred into the spacecraft body frame. Transformation between orbital frame and body frame can be linear or nonlinear; the validity of linear transformation is investigated regarding various attitude angles. The divergence plots and the plot and table of error percentage illustrate the result based on the defined acceptable error.
https://www.ije.ir/article_72501_d6a9b36db9a1a2e55c6ac2c6def2b554.pdf
the earth’s magnetic field
Spacecraft attitude control
linear and nonlinear transformation
orbital frame
body frame
eng
Materials and Energy Research Center
International Journal of Engineering
1025-2495
1735-9244
2015-05-01
28
5
654
661
72502
Characterization of Polypyrrole-hydroxyethylcellulose/TiO2 Nanocomposite: Thermal Properties and AFM Analysis
mahmoud Roushani
mahmoudroushani@yahoo.com
1
marzie Kolbadi nezhad
marzie_kolbadi@yahoo.com
2
Zahra Tagipour kolaei
zk_taghipour@yahoo.com
3
marjan tanzifi
m.tanzifi@ilam.ac.ir
4
Department of Chemistry‎, ilam university
School of Chemical Gas and Petroleum Engineering, , semnan university
Department of Chemical Engineering, Babol University of Technology
Department of Chemical Engineering, ilam university
Polypyrrole–hydroxyethylcellulose/TitaniumDioxide (PPy-HEC/TiO2) nanocomposite was synthesized via in situ chemical oxidative polymerization method at room temperature in water and water/ethyl acetate solution in the presence of ferric chloride (FeCl3). The effect of TiO2 nanoparticles and HEC on the characteristics of products such as thermal stability and morphology was investigated. The fabricated composite and nanocomposite morphology and structure were examined by atomic forced microscopy (AFM), Scanning electron microscope (SEM), Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD) and Thermal gravimetric analysis (TGA). The AFM images of products indicated that hydroxyethylcellulose decreased the surface roughness of nanocomposite. Also, hydroxyethylcellulose decreased particle size. The molecular structure of product was determined by FTIR spectroscopy. The results of XRD confirmed crystalline structure of TiO2 nanoparticles and partly crystalline structure of PPy-HEC/TiO2 nanocomposite. Thermogravimetric analyzer (TGA) was used to study the thermal behavior of nanocomposite. The TGA curves indicated that TiO2 and HEC enhanced thermal stability of products.
https://www.ije.ir/article_72502_02866ed1b8d77a53e0348ec832704c57.pdf
Polypyrrole
hydroxyethylcellulose
Titanium Dioxide
thermal properties
AFM analysis
eng
Materials and Energy Research Center
International Journal of Engineering
1025-2495
1735-9244
2015-05-01
28
5
662
670
72503
The Effect of Tuned Mass Damper on Seismic Response of Building Frames with Uncertain Structural Characteristics
F. Nateghi
nateghi@iiees.ac.ir
1
structure, IIEES
Tuned mass dampers (TMDs) could be used to absorb the input energy of the applied load, and reduce the response of the building frames. However, the effectiveness of TMD in reducing the response of the building frames could be affected by inherited uncertainties in the structural characteristics of the frames. In this study, in order to investigate the probabilistic response of steel moment-resisting frames equipped with TMDs, variation in the failure probability of the structurehasbeen studiedthrough cumulative damage representative for the stories of the structure.The damage representative of each story has been calculated from the cumulative damage indexof the structural elements, based on the weighted average approach. Although the response of the deterministic model of the structure could be reduced by installing TMD, the results of the numerical simulation son the probabilistic response of the structures indicate that for the records that cause excessive damage in the stories of the structures, the effect of the TMD on failure probability of the structure could be detrimental.
https://www.ije.ir/article_72503_0dd186172ca3295424836992bfa5593f.pdf
cumulative damage
Uncertainty
Failure probability
Tuned mass damper
eng
Materials and Energy Research Center
International Journal of Engineering
1025-2495
1735-9244
2015-05-01
28
5
671
676
72504
Experimental and Theoretical Investigation on Shear Strengthening of RC Precraced Continuous T-beams Using CFRP Strips
noridh mohamed
noridh@uthm.edu.my
1
Blkasem Elrawaff
mr84bl@hotmail.com
2
Abdul Aziz Abdul Samad
aziz@uthm.edu.my
3
Marwan Alferjani
mr84bl@yahoo.com
4
Environmental and Civil engineering, UNIVERSITI TUN HUSSEIN ONN MALAYSIA
Civil engineering, Omar AL Mukhtar University, Libya
Department of Water & Environmental Engineering, University Tun Hussien Onn Malaysia
Environmental and Civil engineering, UNIVERSITI TUN HUSSEIN ONN MALAYSIA
Carbon fiber reinforced polymer (CFRP) sheets are externally bonded to reinforced concrete (RC) members to provide additional strength such as flexural, shear, etc. It has been widely accepted that carbon fiber reinforced polymers (CFRPs) can be used effectively to strengthen reinforced concrete (RC) members. This paper is intended to study and use externally bonded CFRP strips to repair and strengthen of RC continuous T-beams, as well as influence of material (CFRP) on repair of shear defect on RC continuous T-beams. And this defect that will repair by using different CFRP strips under sustained loading. Total of three RC continuous T-beams with identical size of 150x320x3650mm, flange width= 400mm and flange thickness = 120mm, and the orientation will involves 0/90 degree and 45/135 degree in 3 sides wrap schemes All beams will be tested under sustained loading. Tests result shows that the effectiveness and shear capacity of the CFRP strengthened specimens. The shear enhancement of the CFRP strengthened beams varied between 26.57% and 38.56% over the control beam. This study confirms that the CFRP strip technique significantly enhances the shear capacity of reinforced concrete shear beams.
https://www.ije.ir/article_72504_e672c02e9267d65a4b8080d674c9d22b.pdf
Continuous Beam
shear strengthening
Flexural
sustained load
eng
Materials and Energy Research Center
International Journal of Engineering
1025-2495
1735-9244
2015-05-01
28
5
677
685
72505
Assessment of Lateral Displacements using Neuro-Fuzzy Group Method of Data Handling Systems
Seyed Morteza Marandi
marandi@uk.ac.ir
1
Mojtaba Goharriz
mojtaba_goharriz@yahoo.com
2
Civil Engineering, Shahid Bahonar University of Kerman
Civil Engineering, Shahid Bahonar University
Lateral spreading is one of the most destructive effects of liquefaction. Liquefaction is known as one of the major causes of ground failure related to earthquake. This phenomenon is likely to occur when the rate of earthquake-induced excess pore water pressure buildup exceeds the rate of drainage. Estimation of the hazard of lateral spreading requires characterization of subsurface conditions. In this study, neuro-fuzzy group method of data handling (NF-GMDH) is utilized for assessment of lateral displacement in both ground slope and free face conditions. The NF-GMDH approach is improved using particle swarm optimization (PSO) algorithm. The comprehensive database used for the development of the model was obtained from different earthquakes. Contributions of the variables influencing the lateral displacement of soil are evaluated through a sensitivity analysis. Performance of the NF-GMDH-PSO models are compared with those yielded using empirical equations in terms of error indicators parameters and the advantages of the proposed models over the conventional method are discussed.
https://www.ije.ir/article_72505_60c06b8329ed56c74ab94dfde622ed4d.pdf
Earthquake
Liquefaction
lateral displacement
NF
GMDH
PSO
Empirical equations
eng
Materials and Energy Research Center
International Journal of Engineering
1025-2495
1735-9244
2015-05-01
28
5
686
692
72506
Design Investigation of Microstrip Patch and Half-Mode Substrate Integrated Waveguide Cavity Hybrid Antenna Arrays
Hamide Dashti
hamide.dashti@gmail.com
1
Electrical engineering, Ferdowsi univ. of Mashhad
In this paper two linear arrays including a linear 1×4 and a planar 2×2 of microstrip patch and half-mode substrate integrated waveguide (SIW) cavity hybrid antenna are introduced and investigated. These are simply implemented using low cost single layer printed circuit board (PCB) process. The array element consists of a rectangular microstrip patch with appropriate dimensions in the vicinity of a semi-cicular SIW resonator which are formed a wideband hybrid antenna. In both antenna arrays a microstrip feeding network including a quartur wave transformer matching circuit has been used to fed the array elements. The size of 1×4 linear array is 1.58λ0×2.87λ0 and planar 2×2 array size is 1.57λ0×1.37λ0. Array structure are numerically and experimentally investigated. The measured and simulated results including reflection coefficient, radiation patterns and gain of the both antenna arrays are reported.
https://www.ije.ir/article_72506_325099e2e9ba13af019d0aff854f0554.pdf
Hybrid antenna
microstrip patch
Substrate integrated waveguide
antenna array
eng
Materials and Energy Research Center
International Journal of Engineering
1025-2495
1735-9244
2015-05-01
28
5
693
700
72507
Digital Controller Designbased on Time Domain for DC-DC Buck Converter
Asghar Taheri
taheri@znu.ac.ir
1
Mohamad amir javadi rad
m.a.javadirad@gmail.com
2
electrical engineering, zanjan university
electrical engineering, zanjan university
In this paper, the digital controller design for compensating the dc-dc buck converter output voltage has been analyzed in the digital domain. The main idea of this paper is patterning the samples of high order ideal controller and using integral square error in determining digital PID coefficients. This approach provides higher precision of digital controller design and eliminates the need for manipulating the coefficients, which in turn will lead to stringent design parameters in response to the system output. The proposed scheme has been simulated in MATLAB software and the results have been presented. The digital controller has been designed based on the proposed method for the buck converter and has been implemented on a TMS320LF2812 DSP core.
https://www.ije.ir/article_72507_a32205bb53162efc75269c8aa5b1242c.pdf
DC
DC Buck Converter
Digital PID controller
Integral Square Error (ISE)
patterning
State
Space Averaged (SSA)
voltage mode control
eng
Materials and Energy Research Center
International Journal of Engineering
1025-2495
1735-9244
2015-05-01
28
5
701
708
72508
A Novel Intelligent Water Drops Optimization Approach for Estimating Global Solar Radiation
hajar bagheri tolabi
hajar.bagheri1@gmail.com
1
Shahrin mod ayob
hajarbagheri1@gmail.com
2
Engineering, Islamic Azad University-Khorramabad Branch
, Universiti Teknologi Malaysia
Normal 0 false false false EN-US X-NONE AR-SA MicrosoftInternetExplorer4 Measurement of solar radiance demands expensive devices to be used. Alternatively, estimator models are used instead. In this paper, a new method based on the empirical equations is introduced to estimate the monthly average daily global solar radiation on a horizontal surface. The proposed method uses Intelligent Water Drops Algorithm as a swarm-based nature-inspired optimization technique. The best coefficients of linear and nonlinear empirical models and global solar radiation are calculated for seven different climate regions of Iran using proposed algorithm written in MATLAB software. The results of the proposed method are compared with other techniques. The result shows that the proposed method is more accurate in estimating the monthly average daily global solar radiation.
https://www.ije.ir/article_72508_323436a33df7e51a5c094f1ea6daffc7.pdf
Intelligent Water Drops Algorithm
Global Solar Radiation
Empirical coefficients
Statistical regression techniques
Empirical based models
Intelligent based models
eng
Materials and Energy Research Center
International Journal of Engineering
1025-2495
1735-9244
2015-05-01
28
5
709
716
72509
Voltage Control Strategy for Direct-drive Robots Driven by Permanent Magnet Synchronous Motors
Mahdi Sadeghijaleh
mahdisadeghi67@yahoo.com
1
Electrical and Robotic Engineering, Shahrood University of Technology
Torque control strategy is a common strategy to control robotic manipulators. However, it becomes complex duo to manipulator dynamics. In addition, position control of Permanent Magnet Synchronous Motors (PMSMs) is a complicated control. Therefore, tracking control of robots driven by PMSMs is a challenging problem. This article presents a novel tracking control of electrically driven robots which is free from manipulator model. The proposed control law is simple but robust against uncertainties associated with manipulator dynamics. The novelty is the developing of voltage control strategy for the direct-drive robots driven by PMSMs. In addition, a state-space model is obtained for the robotic system including the direct-drive robot manipulator and the PMSMs. Then, the proposed approach is verified by stability analysis. A comparative study through simulations shows the superiority of the voltage control strategy to the torque control strategy.
https://www.ije.ir/article_72509_8db9ee3a3c5eec31a4ffea6d45bd585a.pdf
Direct
drive robot
Permanent Magnet Synchronous Motor
torque control strategy
Voltage Control Strategy
eng
Materials and Energy Research Center
International Journal of Engineering
1025-2495
1735-9244
2015-05-01
28
5
717
729
72510
A Reliable Multi-objective p-hub Covering Location Problem Considering of Hubs Capabilities
mohammad rezanezhad
rezanezhad.mr@gmail.com
1
Mahdi Bashiri
bashiri.m@gmail.com
2
Industrial Engineering, Shahed University
Industrial Engineering, Shahed University
In the facility location problem usually reducing total transferring cost and time are common objectives. Designing of a network with hub facilities can improve network efficiency. In this study a new model is presented for P-hub covering location problem. In the p-hub covering problem it is attempted to locate hubs and allocate customers to established hubs while allocated nodes to hubs are inside of related hubs covering radius. In this paper we attempt to consider capability of established hubs according to their corresponding capabilities on sorting operation. Moreover the reliability of network is considered in the proposed model as an objective. The proposed multi objective model is solved by ε-constraint algorithm for small size instances. For large scale instances a non-dominated sorting genetic algorithm (NSGA-II) is presented to obtain Pareto solutions and its performance is compared with results of ε-constraint algorithm. The model and solution algorithm were analyzed by more numerical examples and some sensitivity analysis have been done. The analysis confirms that the network extracted by the proposed model is more efficient than classic networks.
https://www.ije.ir/article_72510_7dc5cef9951ffbfd9d5a2b022b0a78e2.pdf
P
hub covering
Hub capability
Reliability
multi objective
eng
Materials and Energy Research Center
International Journal of Engineering
1025-2495
1735-9244
2015-05-01
28
5
730
737
72511
Redundancy Allocation Combined with Supplier Selection for Design of Series-parallel Systems
Ali Asghar Tofigh
ali.a.tofigh@gmail.com
1
Roya Soltani
roya.soltani@gmail.com
2
Department of Industrial Engineering, Islamic Azad University
In this paper a redundancy allocation problem is studied where for the first time the supplier selection is taken into consideration and redundant components are provided from appropriate suppliers with the most suitable offers such as discount on buying price of components, warranty length for components, things like that, so that the system reliability, profit and the warranty length proposed by suppliers are simultaneously maximized. The resulted multi-objective model is then dealt with the well-known compromise programming approach and the performance of the proposed model is investigated through a numerical example.
https://www.ije.ir/article_72511_4b3e0c6d73cbbb3b89e921d6c70e3f04.pdf
system design
Redundancy allocation
Supplier selection
Price discounting
Compromise Programming
eng
Materials and Energy Research Center
International Journal of Engineering
1025-2495
1735-9244
2015-05-01
28
5
738
745
72512
A Two Stage Stochastic Programming Model of the Price Decision Problem in the Dual-channel Closed-loop Supply Chain
mahboobeh honarvar
mhonarvar@yazd.ac.ir
1
Ahmad Ahmadi Yazdi
ahmad_ahmadi_yazdi@yahoo.com
2
Industrial Engineering, Yazd University
Industral Engineering, Yazd University
In this paper, we propose a new model for designing integrated forward/reverse logistics based on pricing policy in direct and indirect sales channel. The proposed model includes producers, disposal center, distributers and final customers. We assumed that the location of final customers is fixed. First, a deterministic mixed integer linear programming model is developed for integrated logistics network design. Then the stochastic counterpart of the proposed mixed integer linear programming model is developed by using scenario-based stochastic approach. We use the value of the stochastic solution (VSS) as a measure to evaluate the accuracy of stochastic programming approach. VSS value showed that using stochastic approach for solving the proposed model is sufficient. Moreover, we could obtain optimal values of sale prices in direct and indirect sale channel and service level by considering forward and reverse flow together.
https://www.ije.ir/article_72512_162d26212be3327814f8767fdd318830.pdf
Logistic Network
reverse logistics
Integrated logistics
Pricing policy
multi
channel sale
eng
Materials and Energy Research Center
International Journal of Engineering
1025-2495
1735-9244
2015-05-01
28
5
746
754
72513
Design of a New Mathematical Model for Integrated Dynamic Cellular Manufacturing Systems and Production Planning
Naeem Aghajani-Delavar
naeem_aghajani@yahoo.com
1
Reza Tavakkoli-Moghaddam
tavakoli@ut.ac.ir
2
Esmaeil Mehdizadeh
emehdi@qiau.ac.ir
3
Industrial Engineering, Qazvin Branch, Islamic Azad University
Industrial Engineering, University of Tehran
Industral Engineering, Qazvin Branch, Islamic Azad University
This paper presents a new mathematical model for integrated dynamic cellular manufacturing systems and production planning that minimizes machine purchasing, intra-cell material handling, cell reconfiguration and setup costs. The presented model forms the manufacturing cells and determines the quantity of machine and movements during each period of time. This problem is NP-hard, so a meta-heuristic algorithm based on genetic algorithm (GA) is developed to solve it. Experimental results confirm the efficiency and the effectiveness of the proposed GA to provide good solutions, especially for medium and large-sized problems.
https://www.ije.ir/article_72513_5d6007a3e98eac4c7d353d5c3447ab53.pdf
cellular manufacturing system
Genetic Algorithm
Cell reconfiguration
Intra cell material handling
eng
Materials and Energy Research Center
International Journal of Engineering
1025-2495
1735-9244
2015-05-01
28
5
755
763
72514
Three-dimensional Vibration Suppression of an Euler-bernolli Beam via Boundary Control Method
Amir Hossein Mosalaeifard
f_mosalaei@yahoo.com
1
Mechanical and Aerospace Engineering, Shiraz University of Technology
In this paper, the general governing equations of three-dimensional vibrations of an Euler-Bernoulli Beam under influences of system dynamics are derived by the Hamiltonian method. Then two fundamental cases of a cantilever beam and a rotating beam are considered. The conventional methods for vibration suppression debit to expenses and make new problems such as control spillover because they are based on reduced or discretized model. So, in order to suppress the beam vibrations the boundary control method is proposed to use. As the control command the boundary forces and moments on the beam ends are designed based on the Lyapunov method. These control commands guarantee the asymptotic stability of the system vibrations. The simulation results illustrate power of the proposed method to suppress the longitudinal and transverse vibrations of the cantilever and the rotating beams.
https://www.ije.ir/article_72514_abf1e1df0a8840bca3911d0ffdfee073.pdf
Three
Dimensional Vibrations
Euler
Bernoulli beam
Boundary Control Method
Fixed beam
Rotary Beam
eng
Materials and Energy Research Center
International Journal of Engineering
1025-2495
1735-9244
2015-05-01
28
5
764
770
72515
State Estimation of MEMs Capacitor Using Taylor Expansion
Hadi Madinei
grezazadeh44@yahoo.com
1
Hamed Mobki
hamedmobki@live.com
2
Mecanical Engineering, Urmia University
Mecanical Engineering, Tabriz University
This paper deals with state estimation of micro tunable capacitor subjected to nonlinear electrostatic force. For this end a nonlinear observer has been designed for state estimation of the structure. Necessary and sufficient conditions for construction of the observer are presented. Stability of the observer is checked using Lyapunov theorem. Observer design is based on converting of differential equation of dynamic error from heterogeneous to homogenous. For this process non-linear electrostatic term is presented as coefficient of error and it is done using decomposition of Taylor expansion of non-linear term. By stabilizing of homogenous differential equation gains of observer can be obtained. Ability of the observer in state estimation of micro tunable capacitor is checked and related results are presented.
https://www.ije.ir/article_72515_96927eb9dff0c226e7b39cf7f91d4c1e.pdf
micro tunable capacitor
Lyapunov theorem
Nonlinear observer
state estimation
Taylor expansion
eng
Materials and Energy Research Center
International Journal of Engineering
1025-2495
1735-9244
2015-05-01
28
5
771
780
72516
Unsteady Heat and Mass Transfer Near the Stagnation-point on a Vertical Permeable Surface: a Comprehensive Report of Dual Solutions
A. Abbassi
abbassi@aut.ac.ir
1
Hossein Tamim
tamimhossein@aut.ac.ir
2
Mechanical enginnering, Amirkabir
Mechanical enginnering, Amirkabir
In this paper, the problem of unsteady mixed convection boundary layer flow of a viscous incompressible fluid near the stagnation-point on a vertical permeable plate with both cases of prescribed wall temperature and prescribed wall heat flux is investigated numerically. Here, both assisting and opposing buoyancy forces are considered and studied. The non-linear coupled partial differential equations governing the flow, thermal and concentration fields are first transformed into a set of non-linear coupled ordinary differential equations by a set of suitable similarity transformations. The resulting system of coupled non-linear ordinary differential equations is solved numerically by using the Runge–Kutta scheme coupled with a conventional shooting procedure. Numerical results are obtained for the skin-friction coefficient, Nusselt number and Sherwood number as well as for the velocity, temperature and concentration profiles for some values of the governing parameters, namely, the unsteadiness parameter A, permeability parameter f0 and mixed convection parameter λ. It is found that dual solutions exist for both assisting and opposing flows, and the range of the mixed convection parameter for which the solution exists, increases with suction and unsteadiness parameters.
https://www.ije.ir/article_72516_b1c356585d1f9dc43852d5f9a0e646b5.pdf
Unsteady flow
Double Diffusive Convection
Stagnation
point Flow
Mixed convection
Dual solutions
Vertical surface
Suction/injection
eng
Materials and Energy Research Center
International Journal of Engineering
1025-2495
1735-9244
2015-05-01
28
5
781
793
72517
Technical Analysis of Conversion of A Steam Power Plant to Combined Cycle, Using Two Types of Heavy Duty Gas Turbines
Sadegh Nikbakht Naser Abad
s.nikbakht@srttu.edu
1
kamran Mobini
kmobini@srttu.edu
2
Abdollah Mehrpanahi
mehrpanahi@srttu.edu
3
Mohammad Reza Ali Goodarz
maligoodarz@srttu.edu
4
Mechanical Engineering, Shahid Rajaee Teacher Training University
Mechanical Engineering, Shahid Rajaee Teacher Training University
Mechanical Engineering, Shahid Rajaee Teacher Training University
Mechanical Engineering, Shahid Rajaee Teacher Training University
Due to long life of steam power plants in Iran, transformation of steam cycles to combined cycles is under consideration. Bandar-Abbas steam power plant with capacity of 320 MW has been analyzed in this work. This old plant is located near the harbor city of Bandar-Abbas at southern Iran. Method of exergy analysis is used to study the current and the repowered systems. Optimum state of the repowered cycle is also obtained using exergy analysis. In this work, a point by point analysis of Bandar-Abbas steam power plant is performed for different modes of full repowering, using exergy analysis method. For this purpose, V94.2 and V94.3A gas turbines are used and effect of duct burner is investigated for each case. The results show that at the best repowering mode, power plant efficiency is 34.5% higher than the design efficiency of the current steam plant. Minimum rate of exergy destruction rate is 6711 MW at this mode and the heat rate reduces by 26.6%. According to the results, increase of fuel consumption in duct burner and use of V94.2 gas turbine are not recommended for repowering of Bandar-Abbas power plant.
https://www.ije.ir/article_72517_4bab0b768f217ca878973a457180d90f.pdf
Technical Analysis Exergy Steam Power Plant Full Repowering Combined Cycle Gas Turbine HRSG
eng
Materials and Energy Research Center
International Journal of Engineering
1025-2495
1735-9244
2015-05-01
28
5
794
801
72518
Dynamic Response Analysis of the Planar and Tubular Solid Oxide Fuel Cells to the Inlet Air Mass Flow Rate Variation
Yasser Mollaie
em_afshari@yahoo.com
1
Mechanical Engineering, University of Isfahan
The purpose of present study is to investigate the dynamic response of two conventional types of solid oxide fuel cells to the inlet air mass flow rate variation. A dynamic compartmental model based on CFD principles is developed for two typical planar and tubular SOFC designs. The model accounts for transport processes (heat and mass transfer), diffusion processes, electrochemical processes, anode and cathode activation and ohmic polarizations, among others. Using developed model the dynamic response of the cell to the step change of the air feed stream conditions is investigated. The results show an almost slow electrical response of the cell to the air mass flow rate step variation that is estimated to be about one hour. Moreover, it can be concluded that the effect of the inlet air flow conditions on a tubular solid oxide fuel cell performance is more noticeable than its effects on a planar SOFC. However, the electrical response time of the tubular type SOFC is calculated about ten times more than the planar type.
https://www.ije.ir/article_72518_3efd4998b1f03a7e16d942cb7633d991.pdf
solid oxide fuel cell
Tubular cell
Planar cell
Dynamic simulation
Time constant
eng
Materials and Energy Research Center
International Journal of Engineering
1025-2495
1735-9244
2015-05-01
28
5
802
811
72519
Nonlinear Bending Analysis of Sector Graphene Sheet Embedded in Elastic Matrix Based on Nonlocal Continuum Mechanics
Masoud Tahani
mtahani@um.ac.ir
1
Mehrdad Jabbarzadeh
jabbarzadeh@mshdiau.ac.ir
2
Shahriar Dastjerdi
dastjerdi_shahriar@yahoo.com
3
Mecanical Engineering, Ferdowsi University of Mashhad
Mechanical Engineering, Islamic Azad University of Mashhad
Mechanical Engineering, Islamic Azad University of Mashhad
The nonlinear bending behavior of sector graphene sheets is studied subjected to uniform transverse loads resting on a Winkler-Pasternak elastic foundation using the nonlocal elasticity theory. Considering the nonlocal differential constitutive relations of Eringen theory based on first order shear deformation theory and using the von-Karman strain field, the equilibrium partial differential equations are derived. the nonlinear partial differential equations system is solved using the differential quadrature method (DQM) and a new semi analytical polynomial method (SAPM). By using the DQM or SAPM, the partial differential equations are converted to nonlinear algebraic equations, then the Newton–Raphson iterative scheme is applied to solve the resulting nonlinear algebraic equations system. The obtained results from DQM and SAPM are compared and observed the SAPM results are so close to DQM. Whereas, the SAPM’s formulations are considerably simpler than the DQM. Different boundary conditions including clamped, simply supported and free edges are considered. The obtained results are validated with available researches, then the small scale effects is investigated on the results due to various conditions such as outer radius to thickness ratio, boundary conditions, linear to nonlinear analysis, nonlocal to local analysis ratio, angle of the sector and stiffness value of elastic foundation.
https://www.ije.ir/article_72519_2e35467d9c4e55605394d6017ccac1b0.pdf
Nonlocal elasticity theory
Nano
graphene sector plates
Differential Quadrature method (DQM)
Semi Analytical Polynomial Method (SAPM)
Elastic Foundation
eng
Materials and Energy Research Center
International Journal of Engineering
1025-2495
1735-9244
2015-05-01
28
5
812
821
72520
Thermal Simulation of Solidification Process in Continuous Casting
Hamed Hosseinzadeh
hmd.hosseinzadeh@gmail.com
1
Ali Jabari Moghadam
alijabari@shahroodut.ac.ir
2
Mechanical Engieering, Shahrood University of Technolgy
In this study, a mathematical model is introduced to simulate the coupled heat transfer equation and Stefan condition occurring in moving boundary problems such as the solidification process in the continuous casting machines. In the continuous casting process, there exists a two-phase Stefan problem with moving boundary. The control-volume finite difference approach together with the boundary immobilization method is selected to predict the position of moving interface and the temperature distribution. The approach is validated by some available models and the agreement is found to be satisfactory. Effects of the governing parameters such as Stefan number and casting speed on the evolution of the freezing front and temperature distributions are investigated. It is found that the variation of Stefan number has a strong influence on the growth of the shell thickness and the temperature distributions. For the same values of heat transferred from the mold, increasing Stefan number has significant results such as: accelerating the solidification process and increasing the solid thickness, enhancing the local heat flux in the liquid, and broadening the liquid zone affected by the cooling water jacket. As the casting speed becomes higher, the molten flow leaves the mold faster and the solid thickness entering the secondary cooling stage is decreased; meanwhile, the central liquid region has less time to be affected by the cooling water. Reducing casting speed results in decreasing the solid temperature; in other words, the solid layer becomes cooler.
https://www.ije.ir/article_72520_5c21399c8dbc1066be53446f2dc5f089.pdf
heat transfer
Continuous Casting
Stefan condition
Casting speed
Boundary Immobilization Method
Front
fixing method