2021-10-19T08:32:21Z
http://scientiairanica.sharif.edu/?_action=export&rf=summon&issue=296
Scientia Iranica
Scientia Iranica
1026-3098
1026-3098
2014
21
3
Effect of a New Wet Soot Absorber on Soot Removal of a Diesel Engine
M.
Ghazikhani
M. E.
Feyz
I.
Khazaee
Ali
Ghazikhani
M. J.
Mahmoudzadeh Akherat
In the following investigation, a submerged-type Wet Soot Absorber (WSA) is studied and its capability on reducing the soot emission level of a four cylinder, direct injection (DI) diesel engine is evaluated. The WSA can provide a large contact area between water and exhaust flow which increases the soot capturing probability. Hence, the system can be more compact and suitable for vehicle engines applications. The ECE-R49 standard test is followed to assess the effect of the WSA on the engine performance and soot emission. The experiments revealed that the best soot removal efficiency of 70% is attained in the full-load engine operating conditions due to the high momentum of exhaust gas flow entering to the chamber of the unit which can provide more flow penetration into the water. Also, further bubble break-up in high gas velocity results in a larger liquid-gas interface and contributes to better soot removal. The minor negative effects of utilizing the WSA on the brake specific fuel consumption (BSFC) is also compared with those of conventional DPFs and the aspects of WSA advantages are discussed.
Wet Soot Absorber
Diesel Particulate Matter
bsfc
2014
06
01
569
577
http://scientiairanica.sharif.edu/article_3496_f8b0685cc8759044e8e95b37f5dfc079.pdf
Scientia Iranica
Scientia Iranica
1026-3098
1026-3098
2014
21
3
Viscoelastic potential flow analysis of stability of a cylindrical jet
Mukesh Kumar
Awasthi
Rishi
Asthana
G. S.
Agrawal
A linear analysis of the temporal instability of a viscoelastic liquid jet with axisymmetric and asymmetric disturbances moving in an infinite viscous fluid is investigated. The cause of the instability in the liquid jet is Kelvin-Helmholtz instability due to the velocity difference and capillary instability due to surface tension. The dispersion relation for viscoelastic potential flow is cubic in nature.The stability analysis shows that viscoelastic liquid jets are less unstable than inviscid jets and more unstable than viscous liquid jets for both axisymmetric and asymmetric disturbances. Stability analysis has been made in terms of various parameters such as Weber number, Reynolds number, Deborah number etc.
Viscoelastic potential flow
Cylindrical jet
Maxwell type fluid
Interfacial flows, viscous stresses
2014
06
01
578
586
http://scientiairanica.sharif.edu/article_3497_9bb99b5099e9fc26a198f8a29c14cbf6.pdf
Scientia Iranica
Scientia Iranica
1026-3098
1026-3098
2014
21
3
Investigation of the dynamic behavior of thick piezoelectric cylinders
H.
Rajabi
A.
Darvizeh
A theoretical solution of the mechanical behavior of thick piezoelectric cylinders subjected to dynamic pressures is presented in this paper. The five governing equations in terms of resultant forces and resultant moments with respect to basic displacement vector components , and are used. Thefirst-order shear deformation theory (FSDT) is employed to consider the effects of shear forces on the shell structure. The effects oftransverse shear deformation and rotary inertiaare included into the analysis. The formulation isbased on the thick-shellequations. Navier-type solutions are obtained and used for simply supported circular cylindrical shells. Finally, the Newmark family of methods is used to numerically time integration of the system of coupled second order ODEs. Results obtained with the present analysis are found to be in good agreement with those available in the literature. The results of this paper can serve as a reference for future study in the design of smart engineering structures.
Theoretical solution
piezoelectric shell
FSDT
Navier solution
Dynamic load
2014
06
01
587
599
http://scientiairanica.sharif.edu/article_3498_341496cf16dc5ea4168b020ea060547b.pdf
Scientia Iranica
Scientia Iranica
1026-3098
1026-3098
2014
21
3
Experimental and Numerical Studies on Resistance of a Catamaran Vessel with Non-Parallel Demihulls
A.
Ebrahimi
M.
Rad
A.
Hajilouy
In common catamaran vessels, demihulls are parallel to each other. In this paper, the total resistance of a catamaran vessel with non-parallel demihulls is investigated experimentally and numerically. Experiments are carried out at different Separation Ratios (S.R.) that is the ratio of fore to aft separation of the catamaran demihulls; and also in two ratios of Length to Separation in amidships (L/Sm). FLUENT solver based on finite volume method (FVM) was used for numerical solution. Applying VOF model, free surface around catamaran vessel and total resistance is calculated and compared with experimental results. Finally, frictional resistance of catamaran from ITTC 1957 correlation line is calculated and compared with CFD frictional resistance. The results show that, non-parallel demihulls cause the total resistance to increase at Froude numbers below 0.8 and decrease resistance at Froude Numbers over 0.8. In the numerical part, at low Froude numbers, numerical results have an error up to 10% relative to model test results, but error increases at high Froude numbers up to 25%.
Catamaran Vessel
Resistance
Non-Parallel demihulls
Model experiments
numerical investigation
2014
06
01
600
608
http://scientiairanica.sharif.edu/article_3499_f4c30489c339ec8184c9a960123acbac.pdf
Scientia Iranica
Scientia Iranica
1026-3098
1026-3098
2014
21
3
Prediction of All-Steel CNG Cylinders Fracture in Impact by Using Damage Mechanics Approach
M.
Yazdani Ariatape
M.
Mashayekhi
S.
Ziaei-Rad
In this paper damage mechanics approach is used to investigate the effect of crash and damage caused by impact in steel cylinder filled by Compressed Natural Gas (CNG). The Canadian Standard Association (CSA) for CNG cylinders is used as a damage detection criterion and cylinders ability to reuse. Johnson-Cook damage model is used to compute the cylinder failures. Simulations are carried out in different impact directions, and the effect of cylinder internal pressure, collision velocity and the fall height are analyzed. Also failures due to collision for various situations are studied and discussed. Investigations for cases including crash and drop tests showed that the maximum damage in cylinder is created for the case of normal impact and by changing the impact direction from normal to side, the amount of damage will be decreased. Also by eliminating failed elements and comparing the damage depth caused by collision using the CSA standard, it was observed that in the most cases of normal accident and drop tests, cylinders have been damaged and lose its ability to use. However, in side impact cases cylinder is intact or can be reused after repairing.
All-Steel CNG Cylinder
Damage Mechanics
Fracture
impact
2014
06
01
609
619
http://scientiairanica.sharif.edu/article_3500_9022c503b867179b6673aa2322bae5a2.pdf
Scientia Iranica
Scientia Iranica
1026-3098
1026-3098
2014
21
3
Effects of non-uniform wall properties on stress distribution in abdominal aortic aneurysm, considering nonlinear constitutive equations
G. R.
Zendehbudi
In this study, stress distribution in aneurismal wall of the abdominal aortic is addressed. Full equilibrium equations derived from the thick-wall theory are solved using the well-known finite-element method (FEM). Nine-node quadratic rectangular plane elements are employed for the spatial discretization of the computational domain. Non-linear constitutive equations and non-uniform wall properties are taken into consideration. The results of this investigation show that in addition to the aneurysm size, some other factors may significantly affect the stress distribution in aneurismal wall. Factors such as wall thickness, blood pressure and longitudinal tension have been identified for both uniform and non-uniform wall properties. Having numerically simulated different cases, it is demonstrated that the longitudinal stress is the maximum stress in the wall and is not significantly affected by the uniformity of the wall stiffness.
Finite Element Method
Aneurysm rupture
Aneurismal wall
Thick-wall theory
Blood pressure, Abdominal aortic aneurysm
Non-linear constitutive equation
2014
06
01
620
627
http://scientiairanica.sharif.edu/article_3501_acbf3fecbe6d54e28f7574321c943f8d.pdf
Scientia Iranica
Scientia Iranica
1026-3098
1026-3098
2014
21
3
Delay-dependent Passive Analysis and Control for Interval Stochastic Time-delay Systems
Cheng
Wang
Zhongwen
Chen
Genyu
Chen
This paper is concerned with the problem of delay-dependent passive analysis and control for interval stochastic time-delay systems. The system matrices are assumed to be uncertain within given intervals, the time delay is a time-varying continousfunction belonging to a given range, and the stochastic perturbation is in the form of a Brownian motion. By using ItÔ’s differential formula and the Lyapunov stability theory, delay-dependent stochastic passive control criteria are proposed without ignoring any useful terms by considering the information of the lower bound and upper bound for the time delay. Based on the criteria obtained, a delay-dependent passive controller that ensures stochastic passivity of the closed-loop system is presented. Then, the controller gain is characterized in terms of LMIs, which can be easily checked by resorting to available software packages. Numerical examples are given to demonstrate the effectiveness of the method.
interval systems
time-delay
stochastic
passivity
linear matrix inequality (LMI
2014
06
01
628
646
http://scientiairanica.sharif.edu/article_3502_5e3246c9589dfa954d08161c6008b492.pdf
Scientia Iranica
Scientia Iranica
1026-3098
1026-3098
2014
21
3
Thermally induced vibration of an electro-statically deflected functionally graded micro-beam considering thermo-elastic coupling effect
Ilgar
Jafarsadeghi-pournaki
Ghader
Rezazadeh
Mohammadreza
Zamanzadeh
Rasool
Shabani
This study investigates the dynamic response of an electrostatically deflected capacitive cantilever functionally graded (FG) micro-beam subjected to a harmonically varying thermal load, which is incited vibration due to different material properties of the beam constituents and thermo-elastic coupling effect. The FG beam is made of mixture of metal and ceramic where the material properties vary continuously through the thickness according to an exponential distribution law (E-FGM).Assuming the Euler-Bernoulli beam theory and the infinite speed of heat transportation, the equation of motion and the conventional coupled energy equation are derived. Applying Galerkin formulation and then using Rung-kutta method as an efficient numerical tool,these equations are simultaneously solved. Changing the ceramic constituent percentage of the bottom surface, five different types of FGM micro-beams are investigated and results are presented for all types.Numerical results are shown the response of a cantilever FG micro-beam subjected to a harmonically varying temperature input. Moreover, the influences of the beam ceramic constituent percentage on the stability, vibrational behavior and natural frequency are presented.
Thermally induced vibration
FGM
thermo-elastic coupling
electrostatic load
2014
06
01
647
662
http://scientiairanica.sharif.edu/article_3503_d1913acbabcf6cf760b21b37240ce248.pdf
Scientia Iranica
Scientia Iranica
1026-3098
1026-3098
2014
21
3
Design and Programming a 3D Simulator and Controlling Graphical User Interface of ICaSbot, A Cable Suspended Robot
M.
H. Korayem
S.M.
Maddah
M.
Taherifar
H.
Tourajizadeh
This paper presents a graphical user interface (GUI) and simulator which is designed for a cable suspended robot (ICaSbot), in LabVIEW environment. This interface is designed to be used for training the users in a virtual environment and also controlling the cable robot in an on-line way. The proposed GUI consists of kinematics, dynamics and on-line control sections. All of the mentioned sections are involved in the simulator of the robot employed to display the motion of the end-effector in a virtual environment. Using the proposed GUI, the user is able to exert the desired commands and study the end–effector motion and all of its kinematics and kinetics output in a virtual environment. Afterward this motion can be applied to the real robot in the part called “hardware control” while six different control methodology can be selected. The controlling commands such as driving the motors and monitoring the actual data which are received from the sensors can be managed in this part of GUI. The efficiency and applicability of the designed GUI is proved by conducting some ISO and experimental tests on the cable robot of IUST called ICaSbot and comparing the results with simulation including of repeatability and accuracy tests and tracking a predefined trajectory.
Cable Robot
Graphical User Interface (GUI)
simulator
Hardware Control
2014
06
01
663
681
http://scientiairanica.sharif.edu/article_3504_3f5e4b144294725284818848a6f6271f.pdf
Scientia Iranica
Scientia Iranica
1026-3098
1026-3098
2014
21
3
Effects of Joule heating and thermophoresis on the stretched flow with convective boundary condition
T.
Hayat
M.
Waqas
S. A.
Shehzad
A.
Alsaedi
Effects of heat and mass transfer on the two-dimensional magnetohydrodynamic (MHD) flow of Maxwell fluid over a stretching surface are discussed. Stretching surface satisfies the convective boundary conditions. In addition, the analysis has been carried out in the presence of Joule heating, thermal radiation and thermophoresis. Governing partial differential equations are first reduced into the ordinary differential equations and then computed for the series solutions. Numerical values of local Nusselt and Sherwood numbers are presented and examined.
thermal radiation
Maxwell fluid
Joule heating
Thermophoresis
Stretching surface
2014
06
01
682
692
http://scientiairanica.sharif.edu/article_3505_0e09c81bb330673425caba535ffb4fc7.pdf