ORIGINAL_ARTICLE
Ultrasonic and Microwave Pretreatment for Hydrothermal Synthesis of Nanosized SAPO-34 and Their Catalytic Performance in MTO Reaction (RESEARCH NOTE)
In order to enhance the catalytic performance of SAPO-34 catalyst for the reaction of methanol to olefins (MTO), ultrasonic and microwave-assisted aging method were employed in static hydrothermal method to synthesize nano-sized SAPO-34. The effects of the application of this method on the chemical composition, morphology, surface area and total acidity of SAPO-34 were characterized by XRD, FE-SEM, nitrogen adsorption–desorption and NH3-TPD techniques. The catalytic performance of synthesized SAPO-34 was investigated for MTO reaction in a fixed-bed reactor under the same operating conditions (T = 450 °C, P =1 atm, and WHSV = 4 h−1). Comparing with the SAPO-34 synthesized with conventional hydrothermal method, sample synthesized with simultaneous use of US and MW-assisted aging methods possesses larger surface area and small crystal size and exhibits higher selectivity to light olefins (C˭2-C˭4) and longer lifetime.
https://www.ije.ir/article_72461_6e17c4b132e0d31abf34b9e199be03af.pdf
2015-03-01
330
337
SAPO
34
Nanocatalysts
MTO Reaction
Lifetime
Light olefins
Majid
Taghizadeh
m_taghizadehfr@yahoo.com
1
Chemical Engineering, Babol Noshirvani University of Technology
AUTHOR
Hassan
Sharifi Pajaie
h.p.sharifi@gmail.com
2
Chemical Engineering, Babol University of Technology
AUTHOR
ORIGINAL_ARTICLE
A Continuum Shell-beam Finite Element Modeling of Buried Pipes with 90-degree Elbow Subjected to Earthquake Excitations
In the current work, the seismic analysis of bent region in buried pipes is performed, and effects of soil properties and modeling methods on pipe’s response are investigated. To do this task Beam, Beam-Shell Finite Element modeling and a Continuum shell FE models of a 90 degrees elbow are employed. In the Beam model, the pipe is simulated by beam elements while combined shell-beam elements are used for the Continuum shell finite element model. The surrounding soil is simulated by nonlinear spring and solid elements; moreover, soil hardening behavior and soil-pipe slippage are considered in the models. In addition, an equivalent boundary condition has been employed at the end of each elbow leg to simulate far field effects more closely. From these analyses, it can be revealed that axial strain at bends is larger in stiffer soil due to smaller slippage. In addition, a full three dimensional soil-pipe interaction using Continuum Shell FE model causes a substantial increase of elbow strain.
https://www.ije.ir/article_72462_9b38055d505a0efb5c2494bcab5a616a.pdf
2015-03-01
338
349
Buried Pipe
elbow
Finite element method
Hybrid Model
Continuum model
M.
Vafaeian
mahmood@cc.iut.ac.ir
1
Civil Engineering, Isfahan University of Technology
AUTHOR
Miad
Saberi
miad.sabery@gmail.com
2
Civil Engineering, Isfahan University of Technology
AUTHOR
ORIGINAL_ARTICLE
Ultimate Unbonded Tendon Stress in CFRP Strengthened Post-Tensioned Indeterminate I-Beams Cast with HSCs
Based on the bending experiment for two-span continuous post-tension beams with unbounded tendons and externally applied CFRP sheets, the analysis of the stress increment of unbonded tendons is monitored in the loading process. Since self-compacting concrete (SCC) is a suitable innovation,, understanding the implementation of this type of concrete on the ultimate unbonded tendon stress is critical. For these aims, results of four continuous un-bonded post-tensioned I-beams in two groups were cast and monitored by electrical strain gauges andare presented here. In the first group, the beams (UPN1-12, SUPN1-12) consisted of high strength normal concrete (HSNC), while in the second group (UPS1-12, SUPS1-12) high strength self-compacting concrete (HSSCC) were tested. The beams are made which are compared with the theory proposed by different codes, and a preliminary modification is given for each code equation. The results of standard error of estimate Sy/x , indicates that for two types of HSCs (strengthened and non-strengthened beams), the ACI 318-2011 provides better estimates than AASHTO-2010 model, whereas this model provides better estimates as compared toBS 8110-97.Comparison of increase in experimental ultimate tendon stress of beams indicates that the increase in tendon stress at ultimate state in strengthened beams is lower than that in non-strengthened beams cast with HSCs.
https://www.ije.ir/article_72463_5dcfee997dba38f846165672e9cb6b56.pdf
2015-03-01
350
359
Strengthened
CFRP Sheet
Unbonded Tendons
Stress Increases
High Strength Normal and Self
Compacting Concrete
Continuous Beams
ali
maghsoudi
maghsoudi.a.uk@gmail.com
1
Civil Engineering, University of Kerman
AUTHOR
Yousef
Askari D.
y.askari@eng.uk.ac.ir
2
Department of Civil Engineering, Shahid Bahonar University
AUTHOR
ORIGINAL_ARTICLE
Predicting Shear Stress Distribution in Rectangular Channels Using Entropy Concept
This study makes use of the Tsallis entropy to predict the shear stress distribution. Given a definition of the Tsallis entropy, it is maximized by using the probability density function, which then is used to attain a novel shear stress equation. This is then employed for calculating the shear stress distribution in rectangular channels in different aspect ratios and finally, for viability, these calculations are compared with some relevant experimental results. This derived shear stress equation is capable of describing the variation of shear stress in both the wall and the bed of channels. The comparison shows that this equation appears to be efficient for predicting the shear stress distribution in rectangular open channels. Mean values of the bed and wall shear stress calculated by the proposed equation have good agreement with the experiments. The shear force percentage calculated from the equation is in good accordance with the experimental measurements.
https://www.ije.ir/article_72464_0829dc02e6f287488d1b4702c3b07f5e.pdf
2015-03-01
360
367
Tsallis enropy
open channel
Shear Force
channel wall
channel bed
Hossein
Bonakdari
bonakdari@yahoo.com
1
Civil Engieering, Razi University
AUTHOR
Mohtaram
Tooshmalani
m.tooshmalani@gmail.com
2
Civil Engieering, Razi University
AUTHOR
ORIGINAL_ARTICLE
Experimental Investigation of the Effect of Splitter Plate Angle on the Under-Scouring of Submarine Pipeline Due to Steady Current and Clear Water Condition
Submarine pipelines are appropriate method for transmission of oil and gas from sea bed. Free spans may occur due to the natural uneven seabed or by under-scouring. Vortex Induced Vibration (VIV) can happen in such free spans at high Reynolds number. Resonance occurs if the frequency of vortex shedding is close to the pipeline’s natural frequency leading to its fatigue that can break the pipeline causing economical and environmental losses. In literature, there are different methods for suppressing the vortex shedding and pipeline vibration and consequent scouring under the pipe such as the usage of splitter plates. In this paper, the effect of splitter plate’s angle on the scouring under the pipeline is studied experimentally. For this purpose, a new experimental setup is designed and constructed in order to allow for the cylinder to vibrate in both in-line and cross flow directions over an erodible bed. The reduced velocity for the experiments is in the range of 2.45-5.06 and gap ratio is zero. Experimental results indicate that the relative scour depth is reduced with increasing the ratio of gap to pipe diameter. By comparing between relative frequency and reduce velocity, we can conclude that the relative frequency gives a constant value for a large air gap ratio ( ) and also, the pipe has not more effect on the bed. Finally, the scouring depth below the mean location of vibration related to the pipes with a splitter plate and angles 0-30 degrees are less than those without a splitter plate. While, inversely, the scouring depth related to the pipes with a splitter plate and an angle between 60-90 is more than those without a splitter plate.
https://www.ije.ir/article_72465_35a5a3fbdf75509fbc0243ebed939782.pdf
2015-03-01
368
377
Pipeline
Vortex induced vibration
Splitter plate
Two degree of freedom
free span
mohammad javad
emamgholizadeh
javad.emamgholizadeh@gmail.com
1
Civil Engieering, Sahand University of Technology
AUTHOR
Ahmadreza
Mostafa gharabaghi
mgharabaghi@sut.ac.ir
2
Civil Engieering, Sahand University of Technology
AUTHOR
Karim
abedi
k_abedi@sut.ac.ir
3
Civil Engieering, Sahand University of Technology
AUTHOR
Mohammad Hossein
Sedaaghi
sedaaghi@yahoo.com
4
Electrical Engieering, Sahand University of Technology
AUTHOR
ORIGINAL_ARTICLE
Free Vibration Analysis of a Sloping-frame: Closed-form Solution versus Finite Element Solution and Modification of the Characteristic Matrices (TECHNICAL NOTE)
This article deals with the free vibration analysis and determination of the seismic parameters of a sloping-frame which consists of three members; a horizontal, a vertical, and an inclined member. The both ends of the frame are clamped, and the members are rigidly connected at joint points. The individual members of the frame are assumed to be governed by the transverse vibration theory of an Euler-Bernoulli beam. To solve this classical problem, a closed-form solution is firstly proposed and then, a numerical analysis is performed for some verification purposes. The closed-form solution is developed by solving the frame equations of motion, directly. For this reason, some mathematical techniques are utilized, such as Fourier transform and the well-known complementary solutions. In this way, some differential equations must be solved, and several boundary conditions should be satisfied. Herein, the more accurate derivation of the last boundary condition is the most important challenge of this paper. This boundary condition is expressed as three distinctive versions, and the free vibration parameters of the frame for the three versions are attained. Moreover, these results are obtained by the use of the finite element method. In this comparison process, some differences are observed between the closed-form and the numerical results. This fact motivated us to propose some modifications in the characteristic matrices of the finite element model of the frame. This modification makes the results of the Finite element method similar to the results of the first version of the closed-form solution. Finally, the natural frequencies and mode shapes are presented for a wide range of angles of the sloping member. Also, two particular cases are discussed and their boundary conditions are presented.
https://www.ije.ir/article_72466_cb6d3a02d394fccaa572338a8c3de1a8.pdf
2015-03-01
378
386
free vibration analysis
Sloping
frame
Boundary condition
Euler
Bernoulli beam
Boundary value problem
Ahmad
Aftabi Sani
ahmad_aftabi@yahoo.com
1
Civil Engineering, Islamic Azad Univesity of Mashhad
AUTHOR
Davoud
Nezamolmolki
davoud.nezamolmolki@gmail.com
2
Civil Engieering, Ferdowsi University of Mashhad
AUTHOR
ORIGINAL_ARTICLE
Application of Interval-valued Fuzzy Analytic Hierarchy Process Approach in Selection Cargo Terminals, a Case Study
Cargo terminals are the gateways for entrance of commodities into the transportation network. Therefore, locating them in optimal location could have a major impact on the cost effectiveness and efficiency of transport, traffic safety and reduction in environmental pollutions. Due to the presence of a large number of parameters involved and the existing uncertainties, decision making in this field is a complex task. If the decision makers cannot reach an agreement on the method of defining linguistic variables based on the fuzzy sets, favorable results and more accurate modeling can be achieved by using the interval-valued fuzzy sets (IVFSs), which provide an additional degree of freedom to represent the uncertainty and fuzziness in the real world. This study presents a group fuzzy analytic hierarchy process (AHP) based on IVFSs (IVF-AHP), and its application to find the optimal location for the Ghaen (Qayenat) cargo terminal in Ghaen City, Iran. The results show that the proposed method is a reliable method in selecting the optimal location for cargo terminals.
https://www.ije.ir/article_72467_cd1036415a372f0bdf2cc974b35e0719.pdf
2015-03-01
387
395
Cargo Terminal
fuzzy AHP
Ghaen (Qayenat) City
Interval
valued fuzzy sets
Group decision making
Hossein
Bonakdari
bonakdari@yahoo.com
1
Civil Engieering, Razi University
AUTHOR
Akbar
Javadi
a.a.javadi@ex.ac.uk
2
AUTHOR
Yasser
Minatour
yasser.4607@gmail.com
3
AUTHOR
Ebrahim
Mirzaei
ebrahim_mirzaei@yahoo.com
4
AUTHOR
ORIGINAL_ARTICLE
Active Suspension System Control Using Adaptive Neuro Fuzzy (ANFIS) Controller
The purpose of designing the active suspension systems is providing comfort riding and good handling in different road disturbances. In this paper a novel control method based on adaptive neuro fuzzy system in active suspension system is proposed. Choosing the proper data base to train the ANFIS has an important role in increasing the suspension system’s performance. The data base which is used to train the proposed ANFIS system is extracted from the outputs of fuzzy, LQR and sliding mode controllers. A quarter-car model is considered to study the performance of the proposed controller. Performance of this controller is compared with the passive system, and active suspension systems with fuzzy and LQR controllers. The results demonstrate that proposed ANFIS controller is better than passive suspension system and active fuzzy and LQR based suspension systems in suspension deflection, body acceleration, settling time and also control force.
https://www.ije.ir/article_72468_e60d8b919ba790b4102927ec3bd44704.pdf
2015-03-01
396
401
Active Suspension System
Fuzzy Logic Controller
ANFIS
Quarter Car Model
Farshad
Samadi
f_samadi89@ms.tabrizu.ac.ir
1
Faculty of Electrical and Computer Engineering, University of Tabriz, Tabriz-IRAN
AUTHOR
Hamid
Moghadam-Fard
hmf1366@gmail.com
2
Faculty of Electrical and Computer Engineering, University of Tabriz, Tabriz-IRAN
AUTHOR
ORIGINAL_ARTICLE
Optimal Placement and Sizing of Fault Current Limiter in a Real Network: a Case Study (TECHNICAL NOTE)
In this paper, the effect of number and fault current limiter(FCL) location has been investigated in order to have maximum reduction of short circuit current level in all buses in a real network. To do so, the faulty buses were identified in terms of short circuit current level by computing short circuits on the desired network. Then, while the fault current limit was modeled, its optimal location and amount for the greatest reduction in the fault current level of the whole critical buses was determined. Optimization computations have been done using the genetic algorithm and method of reducing the search space and all implementation stages of the proposed algorithm and reduction of search space has been conducted in DIgSILENT software using programming language DPL. The obtained results indicate the high efficiency of the proposed method in reducing the short circuit current level of faulty buses and simultaneous improving the power quality.
https://www.ije.ir/article_72469_bdc65653e4690aead38017bfb9f74299.pdf
2015-03-01
402
409
Fault current limiter
Short circuit capacity
Genetic Algorithms
DIgSILENT
Arman
Golzarfar
arman_golzarfar@yahoo.com
1
, Yazd Regional Electric Company
AUTHOR
Ali Reza
Sedighi
sedighi@yazd.ac.ir
2
Electrical Engineering, Yazd University
AUTHOR
Abolfazl
Asadi
abasadiz@gmail.com
3
, Yazd Regional Electric Company
AUTHOR
ORIGINAL_ARTICLE
Discrete Multi Objective Particle Swarm Optimization Algorithm for FPGA Placement (RESEARCH NOTE)
Placement process is one of the vital stages in physical design. In this stage, modules and elements of circuit are placed in distinct locations according to optimization basis. So that, each placement process tries to influence on one or more optimization factor. In the other hand, it can be told unequivocally that FPGA is one of the most important and applicable devices in our electronic world. So, it is vital to spend time to better learning its structure. VLSI science looks for new techniques for minimizing expense of FPGA in order to gain better performance. Diverse algorithms are used for running FPGA placement procedures. It is known that particle swarm optimization (PSO) is one of the practical evolutionary algorithms for this kind of applications. So this algorithm is used for solving placement problem. In this work, a novel method for optimized FPGA placement has been used. According to this process, the goal is to optimize two objectives defined as wire length and overlap removal functions. Consequently, we are forced to use multi-objective particle swarm optimization (MOPSO) in the algorithm. Structure of MOPSO is in a way that introduces set of answers, we have tried to find a unique answer with minimum overlap. This is worth noting that discrete nature of FPGA blocks forced us to use a discrete version of PSO. In fact, we need a combination of multi-objective PSO and discrete PSO for achieving our goals in optimization process. Tested results on some of FPGA benchmark (MCNC benchmark) are shown in “experimental results” section, compared with popular method “VPR”. These results show that proper selection of FPGA’s size and reasonable number of blocks can get us good response.
https://www.ije.ir/article_72470_9ace21fba5258fe6750b946043c2e494.pdf
2015-03-01
410
418
Discrete MOPSO
Optimization algorithm
FPGA placement
VLSI design
wire length cost function
overlap removal
Hosna
Akbarpour
hosna_akbarpoor@yahoo.com
1
Elecctrical, Razi University
AUTHOR
Gholamreza
Karimi
ghkarimi@razi.ac.ir
2
2Electrical Engineering Department, Razi University of Kermanshah, Iran
AUTHOR
Arash
Sadeghzadeh
a.zad@razi.ac.ir
3
Elecctrical, Razi University
AUTHOR
ORIGINAL_ARTICLE
Low Settling Time All Digital DLL For VHF Application
Settling time is one of the most important parameter in design of DLLs. In this paper we propose a new high speed with low settling time Delay Locked Loop (DLL) in which a digital signal processor (DSP) is used instead of using phase-frequency detector, charge pump and loop filter in conventional DLL. To have better settling time, PRP conjugate gradient algorithm is used to optimize delay of each delay cells. Since this novel architecture has removed phase detector, charge pump and loop filter, the proposed structure shown occupy smaller chip area and has less settling time than conventional DLLs. This method could be implemented in a real system by means a digital signal processor device. Simulation has been done for 15 delay cells and fREF is chosen 14MHz to have output frequency 14×15=210MHz. fOUT=210 MHz is one of the channels in Iran VHF frequency band. As shown with simulations, the proposed architecture has locking time approximately 286nsec which is equal to 4 clock cycles of reference clock.
https://www.ije.ir/article_72471_35e1fe8b29d54ede5c6b27e3b899ad2f.pdf
2015-03-01
419
425
DLL
Delay Locked Loop
PRP Conjugate Gradient Algorithm
optimization
Multiplier
Gholamreza
Ardeshir
g.ardeshir@nit.ac.ir
1
Elect & Computer Engineering, Babol Nooshirvani University of Technology
AUTHOR
Mohammad
Gholami
m.gholami@umz.ac.ir
2
Electrical & Electronic Engineering, University of Mazandaran
AUTHOR
Hamid
Rahimpour
hmd_rahimpour@yahoo.com
3
Electrical & Computer Engineering, University of Tehran, College of Engineering
AUTHOR
H.
MiarNaimi
h_miare@nit.ac.ir
4
Computer & Electrical Engineering, Babol Noshiravani University of Technology
AUTHOR
ORIGINAL_ARTICLE
Fuzzy Approximation Model-based Robust Controller Design for Speed Control of BLDC Motor
This paper presents a new controller for speed control problem of the BLDC motors. The nonlinear model of the motor is approximated by implementation of fuzzy rules. The uncertainties are considered in the fuzzy system. Using this model and linear matrix inequality (LMI) optimization, a robust controller for purpose of speed control of the motor has been designed and applied to it. The effectiveness of the designed controls demonstrated through simulation results.
https://www.ije.ir/article_72472_ff78eeeb998b0a2360231a514bce07ac.pdf
2015-03-01
426
432
BLDC motor
fuzzy approximation
Robust controller
Mahdi
Zolfaghari
mahdizolfaghari66@gmail.com
1
Elecrtical Enginnering, Amir Kabir Univ. of Tech.
AUTHOR
Seyed Abbas
Taher
sataher@kashanu.ac.ir
2
Elecrtical and Computer Enginnering, Kashan University
AUTHOR
ORIGINAL_ARTICLE
A Continuum Model For Stone-wales Defected Carbon Nanotubes
In this paper, a continuum model is proposed so that a Stone-Wales (SW) defected carbon nanotube (CNT) is replaced by an initial circumferential crack in a continuum cylindrical shell. For this purpose, the critical energy release rate and then the fracture toughness of a defected CNT are calculated using the results of an existing atomistic-based continuum finite element simulation. Finally, the equivalent crack length is obtained from the fracture toughness. The proposed model can be applicable tovarious kinds of continuum-based simulations of nano-structures like nano-composites and nano-probes where the fracture resistance studies become important. It is concluded for a case study that the armchair (12, 12) CNT containing a SW defect could be replaced with a continuum cylindrical shell with a circumferential crack length of 0.83 nm. Furthermore, the damage variable is discussed to achieve a method for estimating the effective Young's modulus of defected nanotubes with numerous defects subjected to the progressive damage. This estimation method is evaluated by the atomistic based FE simulation of a double defected CNT.
https://www.ije.ir/article_72473_42a61f51ce3d2a1cb157c37c4ec73a5d.pdf
2015-03-01
433
439
Nanotube
Continuum model
Fracture toughness
energy release rate
Damage
Behnam
Saboori
b_saboori@iust.ac.ir
1
School of Mechanical Engineering, Iran University of Science and Technology (IUST)
AUTHOR
Hadi
Moshrefzadeh-sani
hadimoshref@gmail.com
2
School of Mechanical Engineering, Iran University of Science and Technology (IUST)
AUTHOR
ORIGINAL_ARTICLE
A Numerical Analysis for the Effect of Slip Velocity and Stenosis Shape on Non-Newtonian Flow of Blood (TECHNICAL NOTE)
The aim of this paper is to study the effect of slip velocity and shape of stenosis on non-Newtonian flow of blood through a stenosed arterial segment. Blood is modeled as Bingham-Plastic fluid in a uniform circular tube with a radially non-symmetric stenosis. The problem is investigated by a joint effort of analytical and numerical techniques. The influence of stenosis shape parameter, slip velocity, stenosis height and yield stress on blood flow through a stenosed artery has been examined. The variations of wall shear stress, resistance to flow, volumetric flow rate and axial velocity with stenosis shape parameter, yield stress and slip velocity have been shown graphically. It is noticed that axial velocity and volumetric flow rate increase with slip but decrease with yield stress. This information of blood could be useful in the development of new diagnosis tools for many diseases.
https://www.ije.ir/article_72474_0bcbce48fce1c6800847539beba81676.pdf
2015-03-01
440
446
Stenosis
Bingham
Plastic fluid model
stenosis shape parameter
Slip velocity
resistance to flow
Wall Shear Stress
Amit
Singh
aksinghrbs@yahoo.com
1
MATHEMATICS, RBS COLLEGE AGRA
AUTHOR
R.K.
Shrivastav
dr.srivastavark@yahoo.com
2
Department of Mathematics, Agra College Agra
AUTHOR
Amit
Bhatnagar
amitbh2112@gmail.com
3
Department of Applied Sciences (Mathematics), Faculty of Engg and Tech, Agra College Agra
AUTHOR
ORIGINAL_ARTICLE
Experimental Analysis of Effects of Ultrasonic Welding on Weld Strength of Polypropylene Composite Samples
In the present study, method of ultrasonic welding of plastics is used to join the overlap of Polypropylene composites reinforced with glass fiber. The effects of process parameters, including time, pressure, vibration amplitude and amount of glass in composite on strength of welds. To reduce the number of tests and cost, the effect of changing parameters on strength was examined through Box-Behnken test by considering four factors at three levels and parameters were optimized to obtain the highest level of strength. The results of present study showed that maximum failure force is about 2.30 KN, and it is observed when air pressure is 1.5 times more, and amplitude is close to more than 32 micron (more than average), length of welding is 0.4 second and amount of glass used is about 10 percent.
https://www.ije.ir/article_72475_5d82535a2bf506192fd1b3e94d2da503.pdf
2015-03-01
447
453
welding
Ultrasonic Weld
Polypropylene Composite
Surface Response Methodology
Weld Failure Force
aliakbar
ghaderi
ghaderi.aliakbar@gmail.com
1
Faculty of Mechanical Eng., Shahid Rajaee Teacher Training University
AUTHOR
Nasrollah
Bani Mostafa Arab
n.arab@srttu.edu
2
Mechanical Engineering, Shahid Rajaee Teacher Training University
AUTHOR
Mohammad morad
Sheikhi
m_sh_1971@yahoo.com
3
Mechanical Engineering, Shahid Rajaee Teacher Training University
AUTHOR
Reza
Nikoi
reza2292@gmail.com
4
Faculty of Mechanical Eng, Shahid Rajaee Teacher Training University
AUTHOR
Abas
Arham Nmazi
arham_namazi@yahoo.com
5
Mechanical Engineering, Shahid Rajaee Teacher Training University
AUTHOR
ORIGINAL_ARTICLE
Effect of Heat Recirculation in Biomass Flame Stability within a Cylindrical Micro-Combustor (TECHNICAL NOTE)
Flame stability inside a cylindrical micro-combustor was studied. Considering occurrence of heat recirculation, the respective relations were written and with parameters such as motion speed of reactants, flame propagation speed and thermal conductivity of the combustor’s wall, flame stability and its location inside micro-combustor were studied. It was found that for each thermal conductivity of the combustor’s wall, there is only one point inside the micro-combustor that if flame is formed in that point, it will be able to remain stable inside micro-combustor. It was also found that for each thermal conductivity of the combustor’s wall, flame inside the combustor remains stable only in one specified range of motion speed of reactants. In addition, blow-off limits were obtained for high and low speeds of reactants inside the combustor for different values of thermal conductivity of the combustor’s wall.
https://www.ije.ir/article_72476_615016b040bccf8e16e06c07ba4a3606.pdf
2015-03-01
454
459
Analytical model
Heat Recirculation
Wood Particles
Burning Velocity
Blow
Off Limits
Mohammad javad
Noroozi
mo.j.noroozi@gmail.com
1
Factuly of Engineering, Ayatollah Borujerdi University
AUTHOR
ORIGINAL_ARTICLE
Study of Degradation of Dry Cooling Tower Performance under Wind Conditions and Method for Tower Efficiency Enhancement (RESEARCH NOTE)
Wind affects adversely the cooling tower thermal performance. A field investigation was carried out to study the thermal performance of Heller cooling towers under wind conditions, involving measurement of wind velocity and its direction around the cooling tower, and obtaining water flow rates and temperatures at the cooling tower inlet and outlet. Results show that air suction at the tower top prevents flow separation at tower periphery. Additionally, due to better airflow distribution over the front cooling sectors, perpendicular to wind direction, the thermal efficiency is improved compared to the sectors on the tower periphery, parallel to wind direction, resulting in about 20% more heat transfer. Moreover, the thermal performance of the front sectors improves with increase in the wind velocity, while it decreases with increase in the wind velocity for the periphery sectors and those at the back of the tower.
https://www.ije.ir/article_72477_1f1358e9cdae8d3612a42a6755f4fd08.pdf
2015-03-01
460
466
Cross wind velocity
Cooling tower
Field measurements
Thermal Performance
Wind direction
M.A.
Ardekani
ardekani@irost.ir
1
Mechanical Engineering, Iranian Research Organization for Science & Techno
AUTHOR
Mohsen
Mazidi Sharfabadi
mazidi@irost.ir
2
Mechanical Engineering, Islamic azad University, Bafgh Branch
AUTHOR
F.
Farhani
f.farhani@irost.ir
3
Mechainical Engineering, Iranian Research Organization for Science & Techno
AUTHOR
ORIGINAL_ARTICLE
Effect of Deflected Membrane Electrode Assembly on Species Distribution in PEMFC
This article presents the results of a numerical study, using computational fluid dynamics (CFD) analysis to investigate the species distribution of proton exchange membrane fuel cells (PEMFCs) with deflected membrane electrode assembly (MEA). These new geometry were examined while employing three-dimensional, single phase, non-isothermal and parallel flow for model of a PEM fuel cell. This numerical research has concentrated on the effect of new kind of deflected MEA while maintaining the same inlet and boundary condition. Initially the CFD result of polarization curve has been validated with the available experimental data and shown good concord then studied deflected and flatted MEA at cathode and anode side. Investigation showed better results for the PEMFC with having both flatted and deflected MEA at cathode side than base model because of having more reacting area, uniform distribution of reactants, better oxygen transportation to the GDL at shoulder region and having less Cathode Overpotential (COP) which is the main causes of losses.
https://www.ije.ir/article_72478_47ca3bbabde5319d2b17e07aa9c83451.pdf
2015-03-01
467
475
Keywords Deflection
Fuel cell performance
PEM fuel cells
Single
phase
iraj
mirzaee
i.mirzaee@urmia.ac.ir
1
mechanical engineering, urmia university
AUTHOR
farzin
Ramin
fr_mech@yahoo.com
2
Mechanic, Tabriz
AUTHOR
morteza
khalilian
m.khalilian@urmia.ac.ir
3
mechanic, university
AUTHOR
s. mehdi
pesteei
m.pesteei@urmia.ac.ir
4
mechanic, university
AUTHOR
ashkan
torkavannejad
ashkantorkavannejad@yahoo.com
5
mechanic, university
AUTHOR
ORIGINAL_ARTICLE
Investigation of Thermo-hydraulic Performance of Circular Tube Fitted with Center-cleared Twisted Tape Using CFD Modeling (RESEARCH NOTE)
The article presents a practical technique for enhancing thermo-hydraulic performance of a circular tube. In this way, numerical method focusing on laminar tubular flow is used to compare the effectiveness of utilizing center-cleared twisted tapes instead of typical shape of short width tapes. Numerical analysis represented that using both center-cleared and typical shape of twisted tapes, Re enhancement reduces the flow resistance. Studying short width twisted tapes showed that decreasing the width of twisted tape, reduces the heat transfer and hydraulic performance. Contrarily, using sufficient clearance for center-cleared twisted tapes can increase the heat transfer. Hence, applying center-cleared twisted tape as a tool of enhancing heat transfer can be a promising and practical idea.
https://www.ije.ir/article_72479_5ed89a37c829ba4a59e608f20f4a431c.pdf
2015-03-01
476
482
Twisted Tape
heat transfer
friction factor
Laminar Tubular Flow
mojtaba
Aghajani Delavar
m.a.delavar@nit.ac.ir
1
Mechanic Engineering Dept, Babol Noshirvani University of Technology
AUTHOR
Yousef
Vazifeshenas
joseph.vazifeshenas@gmail.com
2
Mechanical Engineering, Babol University of Technology
AUTHOR
ORIGINAL_ARTICLE
The Research on the Biggest Borehole Curvature that Allowed through for the Rotating Casing (RESEARCH NOTE)
With the development of highly-deviated well cementing techniques, rotating casing cementing technology has got more and more attention. The rotating casing technique can improve the displacement efficiency of cement paste, and then enhance the quality of well cementation. In the stuck section, the rotating casing can redress the well to make the casing run sequentially. The casing endures shear stress in rotating, besides axial stress, bending stress, circumferential stress and radial stress are produced by inside and outside casing pressure stress. These forces make it more complicated when calculate the maximum curvature in rotating condition than that without rotation. The paper, by analyzing the casing stresses in rotating condition, assumes a stress model of the casing infinitesimal for rotating casing, puts forward the calculation method for the maximum allowable borehole curvature in casing bucking deformation, or when casing couplings and thread seal fail under rotating condition and determines the biggest borehole curvature that allowed though, laying a base for the design and construction of the highly-deviated well casing.
https://www.ije.ir/article_72480_e534d4420d0f6a34cc58b75ea892d222.pdf
2015-03-01
483
489
rotating casing
maximum allowable borehole curvature
Plastic Deformation
casing yield limit
tensile strength
tap sealed
Huimin
Yuan
yuanhuimin2014@126.com
1
Petroleum Engineering Institute, China University of Petroleum (east China)
AUTHOR
Chunhao
Wan
wanchunhao1@126.com
2
Petroleum Engineering Institute, China University of Petroleum (east China)
AUTHOR
Liu
Yiling
liuyilingupc@163.com
3
Petroleum Engineering Institute, China University of Petroleum (east China)
AUTHOR
Yuhuan
Bu
buyuhuan@163.com
4
Petroleum Engineering Institute, China University of Petroleum (east China)
AUTHOR
Longlong
Ge
00liuyiling@163.com
5
Petroleum Engineering Institute, China University of Petroleum (east China)
AUTHOR