فهرست مطالب

International Journal of Engineering
Volume:29 Issue: 4, Apr 2016

  • TRANSACTIONS A: Basics
  • تاریخ انتشار: 1395/03/02
  • تعداد عناوین: 18
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  • Z. Kouchak Yazdi, I. Alemzadeh* Pages 436-443
    Conjugated Linoleic Acid (CLA), Glycerol (G) and sunflower oil blends with varying concentration were subjected to enzymatic esterification using a 1, 3- specific immobilized lipase. CLA was used as acyl due to its purported health benefits. The transesterified lipids were evaluated for free fatty acids (FFA) and composition of fatty acids by gas chromatography. Lipozyme Rhizomucor mehei immoblized (RM IM) is preferred for enzymatic esterification because of more CLA incorporation and less free fatty acids at the end of reaction than Lipozyme Thermomyces lanuginosus (TL) IM. Response surface methodology (RSM) was used to determine the effects of three variables Glycerol concentration, reaction temperature, and amount of enzyme on the lipase catalyzed incorporation of CLA into Sunflower oil. The optimum condition for maximum CLA incorporation (96.7% Incorporation Yield), maximum reaction rate (0.0271 M/h) and minimum free fatty acids production (Acid No.2.73) was obtained, at 75 C by using 3 % enzyme and 0.27 M glycerol.
    Keywords: Conjugated Linoleic Acid, Response Surface Methodology, Sunflower Oil, Immobilized Lipase
  • A. Parsasadr, A. Ahmadi*, A. Keramat Pages 444-453
    The use of pumps linked in parallel or series in large scale pipe systems is usually inevitable, to meet the required head and discharge. Transient flow occurs following a pump failure in a pump group as a result of variations in the flow rate. This research is an investigation about waterhammer caused by one or more pump-switch off in a pump group when they are connected in parallel. The operation of each pump in the group during steady and unsteady state is analyzed. For this purpose, the fluid flow equations as well as the pumps relations including rotational speed change and head loss are combined and simultaneously solved in the time domain by the method of characteristic. From the results one can quantitatively conceive that the intermittent shut-down compared to suddenly switching off the whole pump group produces much less waterhammer pressures. Furthermore in the intermittent shut-down with different pump characteristics, it is suggested to firstly switch off the most powerful pump, and then the rest which are weaker. Appropriate interpretation about the transition results have been included.
    Keywords: Method of Characteristics, Steady, Transient Flow, Parallel Pumping System, Pump Failure, Waterhammer
  • S. Binbin, G. Song*, W. Zhe, L. Junwei Pages 454-463
    To achieve higher economy of the original driving scheme with single motor and settled gear ratio, new configurations with different powertrain systems in front and rear axle were designed. Firstly, according to the power and torque required by a micro electric vehicle (mEV) in various drive cycles, the parameters of a small and high power motor were determined. Secondly, for schemeⅠwith dual motor and one-speed gearbox, based on genetic algorithm (GA), theoptimal transmission and torque distribution were confirmed. Owing to the use of single-motor-drive mode (SMDM), the simulated energy consumption decreases by 4.01% compared with the original scheme, but the motor efficiency is still relatively low under low-speed conditions (0-1000r/min) due to the fixed transmission. Then, to solve this problem, scheme using two-speed gearbox to substitute the original one in rear axle was proposed. For this scheme, first of all, the explicit relation of energy consumption and the two-speed ratios was established based on response surface methodology (RSM); then hill climbing method was used to search the best ratios. Finally, economy performances of different schemes were discussed in simulation model and energy consumption of this scheme decreases by 7.55% compared with the original one.
    Keywords: Micro Electric Vehicle, Dual Motor, Powertrain System, Response Surface Methodology, Parameters Design
  • F. Ashrafzadeh, S. Tariverdilo*, M.R. Sheidaii Pages 464-472
    Water storage tanks not designed explicitly for seismic loading could require retrofit. One of the common ways of retrofit include some structural change in the lateral load resisting system that could be expensive and requires the tank to be out of service for relatively long time. This paper introduces a novel method to reduce seismic demand on tank’s wall without structural intervention. This is done by employing air cushions adjacent to the wall. The paper investigates the effect of air cushion system on the seismic response of the cylindrical water storage tanks. While in tank without air cushion, the boundary condition adjacent to tank wall is kinematic with no control on the wall pressure, in the proposed method this boundary condition becomes kinetic, enabling control of dynamic fluid pressure on the tank walls. The response parameters of the tank is developed in terms of wall pressure, wave height, base shear, and overturning moment in cylindrical tanks of different sizes with and without air cushions under the far field and near source ground motions. The results demonstrate that the proposed method is an effective way to reduce sloshing force demand.
    Keywords: Cylindrical Water Storage Tanks, Air Cushion, Seismic Response, Boundary Condition, Wall Pressure
  • S. Binbin, G. Song*, L. Bo Pages 473-481
    In this paper, the effect of the Intake Valve Deactivation (IVDA) on engine performance is investigated in detail. Based on an optimization platform with Genetic Algorithm (GA) and engine thermodynamic model, the characteristics of the engine volumetric efficiency and pumping loss were studied under the cam-drive, Single Intake Valve (SIV) and Dual Intake Valves (DIV) operating modes, and the effect of the IVDA on the engine fuel economy was revealed with taking the power consumption of the Electromagnetic Actuated Valvetrain (EAVT) system into consideration. Then, switch rules for the SIV and DIV mode was proposed, and the switching boundary conditions between them were confirmed. Finally, the optimal intake valve close timings for the EAVT system were obtained. Results show that, under the low speed conditions, the SIV mode has little influence on the engine volumetric efficiency, while within the high speed conditions the effect of the IVDA on the volumetric efficiency is significant; compared with the traditional cam-drive valvetrain, the pumping loss of the EAVT engine decreases significantly and shows unique characteristics due to the use of the EIVC strategy; with the use of the IVDA scheme, the energy consumption of the EAVT system reduces, but the engine pumping loss increases in the meantime, both balance their influence on the engine fuel economy. In general, the IVDA scheme is preferred if the engine volumetric efficiency can be ensured, otherwise, the DIV mode takes priority over the SIV mode to maintain the engine power performance.
    Keywords: Camless Valvetrain, Electromagnetic Actuated Valvetrain, Intake Valve Deactivation, Early Intake Valve Closing
  • M. Monadi*, H. M. V. Samani, M. Mohammadi Pages 482-489
    This paper presents a method concerning the integration of the benefit/cost analysis and the real genetic algorithm with various elements of reservoir dam design. The version 4.0 of HEC-RAS software and Hydro-Rout models have been used to simulate the region and flood routing in the reservoir of the dam, respectively. A mathematical programming has been prepared in MATLAB software and linked with the optimal programming then employed to maximize the benefit/cost ratio of the reservoir dam construction. After a sensitivity analysis, mutation and crossover probability are assumed to be 0.05 and 0.7, respectively. The objective function of the study is benefit/cost ratio. The combined methodology has been provided to help to compute the optimal normal water level, length of spillway and downstream levee height of a reservoir dam considering flood control and cost of construction. This is the first attempt to optimize these important parameters, in the construction of a reservoir dam, together considering flood control and economical aspects. It has been displayed that the proposed method provides strong and suitable solutions to determine these parameters. The results showed that there is potential for application of genetic algorithms to such optimization problems, where the objective function is nonlinear and other optimization techniques may be troublesome to apply and find the global optimum.
    Keywords: Optimization, Normal Water Level, Spillway Length, Genetic Algorithms, MATLAB Software, Reservoir Dam, Sonateh Dam
  • M. H. Vali, B. Rezaie*, Z. Rahmani Pages 490-499
    This paper addresses control design in networked control system by considering stochastic packet dropouts in the forward path of the control loop. The packet dropouts are modelled by mutually independent stochastic variables satisfying Bernoulli binary distribution. A sliding mode controller is utilized to overcome the adverse influences of stochastic packet dropouts in networked control systems. Firstly, to determine the parameters of switching function used in the sliding mode control design, an improved genetic algorithm is applied. The proposed improved genetic algorithm provides a fast convergence rate and a proper dynamic performance in comparison with conventional genetic algorithms especially in online control applications. Then, an adaptive neural sliding mode control based on radial-basis function neural network approximation is proposed to eliminate chattering phenomenon in the sliding mode control. A numerical example is given to illustrate the effectiveness of the proposed controller in networked control systems. The results show that the proposed controller provides high-performance dynamic characteristics and robustness against plant parameter variations and external disturbances.
    Keywords: Networked Control Systems, Packet Dropouts, Sliding Mode Control, Genetic Algorithm, Radial, basis Function Neural Network
  • Z. Liwen*, S. Ming, L. Na, Z. Qipeng, C. Xiangzheng Pages 500-504
    The detection probability of visible light reconnaissance equipment is one of key indexes to assess the performance of the system. The detection probability is determined by many factors, such as atmospheric visibility, target-background contrast, target size and distance, solar elevation angle etc. Based on the detection probability model of the visible light reconnaissance equipment to gain targets, chief factors affecting the reconnaissance capability of the visible light reconnaissance equipment are analyzed. With the simulation calculation of the model, the relations between the detection probability model of the visible light reconnaissance equipment and the parameters, which including the contrast between the target and background, atmospheric visibility, the solar elevation angles, the optical system magnification and intercept range, are analyzed. All these are beneficial to further evaluate the reconnaissance capabilities of the visible light reconnaissance equipment.
    Keywords: Visible Light Reconnaissance Equipment, Detection Probability, Intercept Range, Target, background Contrast
  • T. Yuvaraja, K. Ramya Pages 505-513
    This paper presents an analytical modeling method of optimal control variables to maximize output power for switched reluctance generators (SRGs) in single pulse mode operation. This method extends the basic theory of the Stiebler model and utilizes the flux linkage function to express the inductance model of SRG. In this paper, the optimal phase current shape of SRG for maximum output power is investigated to determine optimal control variables based on phase current model. The expression of phase current in this paper that is in terms of control variables is solved using the basic equation of phase voltage based on inductance model, and then the characteristics of phase current and the energy conversion relations are analyzed to determine optimal shape of phase current. Furthermore, the expressions of phase flux linkage, rms phase current, and phase torque based on the proposed phase current model are presented in this paper to know the trend of main electrical losses. Results from analysis show that the switched reluctance generator with the optimal control variables can produce maximum output power and the shape of phase current in this case is flat top. Simulation and experimental results are presented to verify the proposed method.
    Keywords: Optimal Phase Current Shape, Control Variables, Switched Reluctance Generator
  • M. R. Maleki, A. Amiri *, R. Ghashghaei Pages 514-523
    In recent years, some researches have been done on simultaneous monitoring of multivariate process mean vector and covariance matrix. However, the effect of measurement error, which exists in many practical applications, on the performance of these control charts is not well studied. In this paper, the effect of measurement error with linearly increasing variance on the performance of ELR control chart for simultaneous monitoring of multivariate process mean vector and covariance matrix is investigated. The multiple measurement approach is also extended to reduce this effect. Also, the performance of the proposed multiple measurement approach is evaluated in terms of average run length (ARL) and standard deviation run length (SDRL). Finally, the application of the proposed monitoring method is illustrated by a real data in manufacturing industry.
    Keywords: Error, Multiple Measurements, Linearly Increasing Variance, Additive Covariate Model, Simultaneous Monitoring
  • H. Mokhtari* Pages 524-529
    The production planning is an important problem in most of manufacturing systems in practice. Unlike many researches existing in literature, this problem encounters with great uncertainties in parameters and input data. In this paper, a single machine capacitated production planning problem is considered and a linear programming formulation is presented. The production costs are assumed to be uncertain parameters. To handle the uncertainties in the model, the grey systems theory is employed and the concept of grey numbers is incorporated into an optimization framework. In such systems, the uncertain parameters with unknown distributions can be handled by grey numbers. The grey linear programming (GLP) is a development of the classical linear programming which allows uncertainty to be effectively communicated into the optimization process. Finally, the uncertain problem is transformed into a GLP, and is solved by two linear deterministic sub-models.
    Keywords: Grey Systems Theory, Linear Programming, Single Machine Production System, Uncertainty
  • M. Gorji, H. Ghassemi*, J. Mohammadi Pages 530-538
    This research has been carried out to determine the marine propeller hydro-acoustic characteristics by Reynolds-Averaged Navier-Stokes (RANS) solver in both uniform and non-uniform wake flow at different operating conditions Wake flow can cause changes in pressure fluctuation and gas effect on propeller noise spectrum. Noise is generated by the induced trailing vortex wake and induced pressure pulses. The two-step Fflowcs Williams and Hawkings (FW-H) equations are used to calculate hydrodynamic pressure and its performance as well as sound pressure level (SPL) at various points around the propeller. The directivity patterns of this propeller and accurate explanation of component propeller noise are discussed. Comparison of the numerical results shows good agreement with the experimental data. Based on these results, effects of wake flow and operating conditions on the noise reduction are investigated.
    Keywords: Marine Propeller, Sound Pressure Level, Hydrodynamic Performance, Noise Reduction
  • S. Ghasemi Kahrizsangi*, A. Nemati, A. Shahraki, M. Farooghi Pages 539-545
    In this study, the effect of variety of Nano- additives doping on the hydration resistance of the MgOCaO system was investigated. Samples were prepared from calcined dolomite and magnesite. Nanoadditives that contained cations with various valences (trivalent and tetravalent) used as a dopant. The bulk density, apparent porosity and hydration resitance were studied and evaluated. Also, phase analysis of samples was conducted by using X-ray diffraction (XRD) and the microstructure investigation was done by scanning electron microscopy (SEM). The use of both additives improved the hydration resistance. However, the important role of the higher-valence cation in improvmnt of the hydration resistance of MgO-CaO materials was revealed. This behavior is believed to be due to the formation of vacancies in solid solution of CaO or MgO with higher–valence cation. Zr4 cation form a solid solution with CaO, which reduce the Ca2 concentration and leads to the improved hydration resistance of the MgO-CaO system. Also trivalent cation led to the formation of some low melting phases such as C2F (2CaO.Fe2O3), CF (CaO.Fe2O3), C3A (3CaO.Al2O3). The formation of these low melting point phases surrounded the CaO and MgO grain, grain-boundaries and thus promoted densification and hydration resistance of the MgO-CaO system.
    Keywords: Nano, Additives, Trivalent, Tetravalent, Hydration Resistance, Solid Solution
  • S. E. Razavi, A. Hosseinpour Shafaghi*, N. Piroozfam Pages 546-553
    In the current paper, the effect of length and angle of a splitter plate on hydro-thermal field in a range of Reynolds number from 40 to 1000 are numerically studied by solving the two-dimensional NavierStokes equations. For discretization of governing equations, PISO algorithm was imposed to segregate the pressure-velocity coupled equations, and second-order upwind discretization scheme was applied for momentum and energy values. A convergence criterion was set to 10-6. The influence of splitter plate attachment on the fluctuating drag forces, vortex shedding and heat transfer behavior was investigated. It was found that the drag force decreases as the splitter plate elongates and the vortices vanish. The average Nusselt number rises with increasing the angle of splitter plate. A reduction in drag force was observed at about 25º. The overall heat transfer increased due to surface enlargement resulting from the splitter plate. In addition, it was seen that by increasing the plate angle up to 25º the outflow temperature grows.
    Keywords: Circular Cylinder, Laminar Flow, Splitter Plate, Heat Transfer Enhancement, Drag Coefficient
  • B. S. Sikarwar*, A. Bhadauria, P.Ranjan Pages 554-562
    The objective of this work is to develop deep theoretical methods that are based on the solution of the integral boundary layer equations for investigating film cooling in liquid rocket engine. The integral model assumes that heat is transferred from hot free stream gas to the liquid film both by convection and radiation. The mass is transferred to the free srteam gas by the well-known blowing process. Downstream of the liquid film, the gas effectiveness is obtained by solving boundary layer integral equations. It incorporates a differential model for calorimeter mixing between liquid vapors in the boundary layer with the free stream gas entrained in the boundary layer. Comparisons with existing theoretical and experimental results indicate the film coating trends were well predicted by the present integral model proposed by us.
    Keywords: Film, Cooling, Analytical, Heat Transfer, Rocket, Model
  • S. Bouabdallah*, A. Atia, A. H. Boughzala Pages 563-571
    We present a numerical study of the rotating flow generated by two rotating disks in co-/counterrotating, inside a fixed cylindrical enclosure similar to the Czochralski configuration (Cz). The enclosure having an aspect ratio A = H/Rc equal to 2, filled with a low Prandtl number fluid (Pr = 0.011), which is submitted to a vertical temperature gradient. The finite volume method has been used to solve numerically the governing equations of the studied phenomenon.We present the steady state flow; and make a comparison between the flow generated by the co-/counter-rotating end disks. This study was caried out for different Richardson numbers; Ri = 0.01, 0.1, 0.5, 1, 2, 3, 5 and 10. The effect of orientation of the magnetic field is also taken into account for different values of the Hartmann number (Ha = 0, 5, 10, 20, 30 and 50). The obtained results show that the strongest stabilisation of the velocity field and heat transfer occurs when the flow generated byco-rotating end disks and the applied of magnetic field in radial direction provied a more stabilisation of the convective flow.
    Keywords: Rotating Flow, Czochralski, Co, Counter, Rotating Mixed Convection, Magnetic Field
  • K. Ajay*, L. Kundan Pages 572-580
    The present work evaluates the performance of solar collector using Al2O3-C2H6O2-H2O nanofluid as a working fluid through both experimental and CFD analysis. Ethylene-glycol water mixture (40:60 v/v) is used as base fluid, where α-Al2O3 nanoparticle of 20 nm average size is dispersed for the preparation of nanofluid of four different volumetric concentration (vol. conc.) of 0.05, 0.075, 0.1 and 0.125%. Three different volume flow rates of 30 LPH, 50 LPH and 80 LPH are used. CFD analysis is carried out through ANSYS FLUENT 14.5. From both experimental and CFD analysis, an improvement in overall efficiency of solar collector is reported when nanofluid is used as compared to water-ethylene glycol mixture. With 0.125% vol. conc. of nanofluid Al2O3-C2H6O2-H2O (DI) maximum overall efficiency of about 4.6, 7.9 and 14.8% is reported at 30 LPH, 50 LPH and 80 LPH, respectively from CFD results while from experimental results maximum overall efficiency of about 4.3, 7.5 and 13.8% is seen at 30 LPH, 50 LPH and 80 LPH, respectively. Also, with increasing volume flow rate of working fluid, corresponding improvement in the overall efficiency of solar collector takes place. Close agreement is also developed between experimental and CFD result.
    Keywords: Solar Energy, Parabolic Solar Collector, CFD, Nanofluid, Thermal Efficiency
  • E. Jamila*, S. Abdelmjid Pages 581-589
    This paper studies the interest of the integration of battery energy storage with Static Synchronous Compensator (STATCOM) for improving the low voltage ride through capability (LVRT) of a fixed speed wind turbine connected to the grid. For this reason and by applying a grid fault, a comparison is made between integrating the SSSC, the STATCOM and the STATCOM with battery energy storage. The system with the aforementioned flexible alternating current transmission system (FACTS) systems is simulated using MATLAB/SIMSCAPE and the results show that the STATCOM with a battery is most efficient in terms of improving the LVRT of a fixed speed wind turbine.
    Keywords: Fixed Speed Wind Turbine, Static Synchronous Compensator, Low Voltage Ride Through Capability Static, Synchronous Series Compensator, Static Synchronous Compensator, Battery