Showing 341 results for Type of Study: Research
M. Salehpour, A. Jamali, N. Nariman-Zadeh,
Volume 1, Issue 4 (12-2011)
Abstract
In this paper, multi-objective uniform-diversity genetic algorithm (MUGA) with a diversity preserving mechanism called the ε-elimination algorithm is used for Pareto optimization of 5-degree of freedom vehicle vibration model considering the five conflicting functions simultaneously. The important conflicting objective functions that have been considered in this work are, namely, vertical acceleration of seat, vertical velocity of forward tire, vertical velocity of rear tire, relative displacement between sprung mass and forward tire and relative displacement between sprung mass and rear tire. Further, different pairs of these objective functions have also been selected for 2-objective optimization processes. The comparison of the obtained results with those in literature demonstrates the superiority of the results of this work. It is shown that the results of 5-objective optimization include those of 2-objective optimization and, therefore, provide more choices for optimal design of vehicle vibration model.
S. Babazadeh Shayan, S. M. Seyedpour, F. Ommi, S. H. Moosavy, M. Alizadeh,
Volume 1, Issue 4 (12-2011)
Abstract
E. Mohammadi, M. A. Moghadam,
Volume 1, Issue 4 (12-2011)
Abstract
F. Javid, E. Esmailzadeh, D. Younesian,
Volume 1, Issue 4 (12-2011)
Abstract
M. R. Ayatollahi, F. Mohammadi, H. R. Chamani,
Volume 1, Issue 4 (12-2011)
Abstract
P. Hosseini-Tehrani, S. Pirmohammad,
Volume 1, Issue 4 (12-2011)
Abstract
M. Durali, M. Sadedel,
Volume 1, Issue 4 (12-2011)
Abstract
N. Tavassoli, A. Darvizeh, M. Darvizeh,
Volume 2, Issue 1 (1-2012)
Abstract
Car body lightening and crashworthiness are two important objectives of car design. Due to their excellent performance, composite materials are extensively used in the car industries. In addition, reducing the weight of vehicle is effective in decreasing the fuel consumption. Hat shape energy absorber is used in car’s doors for side impact protection.
The aim of these numerical models and experimental tests is to unveil some important fact about using composite materials in hat shape energy absorber and also show the effect of orientation angles on the amount of energy absorption. The effects of different orientation angles on crushing behavior of hat shape structure are presented.
M. H. Shojaeefard, R. Talebitooti, M. Amirpour Molla, R. Ahmadi,
Volume 2, Issue 1 (1-2012)
Abstract
S. Javan, S. V. Hosseini, S. Sh. Alaviyoun,
Volume 2, Issue 1 (1-2012)
Abstract
Temperature is one of the effective parameters in erosion of spark plug electrodes. In this research, temperature of
spark plug was measured in engine's different operation conditions with two types of fuels: compressed natural gas and
gasoline. Test results showed that, temperature of center electrode is lower than ground electrode and maximum
difference between them is 110ºC that occurs at 2500 rpm and full load conditions. Maximum temperature of spark
plug occurs with CNG under full load conditions and 6380 rpm. In these conditions, ground electrode’s temperature
reaches to 960ºC which is very prone to pre-ignition. On the other hand, center electrode’s temperature is 195ºC higher
than the same condition with gasoline as a fuel which cause more electrode erosion rate. This temperature rise lead to
cold type spark plug selection because of its better heat transfer. Spark plug erosion was studied after endurance tests
with CNG as a fuel. Electrodes have non uniform wear patterns and consequently gap growth is not uniform. The
average gap growth for two sets of spark plugs after two similar 200 hr endurance tests is 49.6%
Sh. Azadi, Z. Taherkhani,
Volume 2, Issue 1 (1-2012)
Abstract
This paper develops an automatic parking algorithm based on a fuzzy logic controller with the vehicle pose for the
input and the steering angle for the output. In this way some feasible reference trajectory path have been introduced
according to geometric and kinematic constraints and nonholonomic constraints to simulate motion path of car. Also
a novel method is used for parking space detection according to image processing. A fuzzy controller according to
experiments of skilled driver and path planning is designed, and then fuzzy rules are tuned and finally fuzzy
membership functions are optimized using genetic algorithm. Simulation results illustrate the effectiveness of the
developed schemes
B. Mashadi, A. Aghaei,
Volume 2, Issue 1 (1-2012)
Abstract
the primary objective of this work is to introduce a gear ratio selection strategy for a CVT equipped vehicle and show
its effectiveness on the fuel consumption reduction. AFuzzy control algorithm is designed for this purpose. Anonlinear
model is developed for simulating the longitudinal vehicle dynamics with accelerator pedal applied by the driver as an
input. In order that pedal input values can be used for evaluation of control strategy, a pedal cycle concept was
introduced. With the help of these cycles different driving conditions were simulated and the fuel consumption results
were obtained using Advisor software. Results showed that the control system was successful in reducing the fuel
consumption, especially in low acceleration driving cycles
A. Khodayari, A. Ghaffari,
Volume 2, Issue 1 (1-2012)
Abstract
Car-following models, as the most popular microscopic traffic flow modeling, is increasingly being used by
transportation experts to evaluate new Intelligent Transportation System (ITS) applications. A number of factors
including individual differences of age, gender, and risk-taking behavior, have been found to influence car-following
behavior. This paper presents a novel idea to calculate the Driver-Vehicle Unit (DVU) instantaneous reaction delay of
DVU as the human effects. Unlike previous works, where the reaction delay is considered to be fixed, considering the
proposed idea, three input-output models are developed to estimate FV acceleration based on soft computing
approaches. The models are developed based on the reaction delay as an input. In these modeling, the inputs and
outputs are chosen with respect to this feature to design the soft computing models. The performance of models is
evaluated based on field data and compared to a number of existing car-following models. The results show that new
soft computing models based on instantaneous reaction delay outperformed the other car-following models. The
proposed models can be recruited in driver assistant devices, safe distance keeping observers, collision prevention
systems and other ITS applications.
D. Vashist, M. Ahmad,
Volume 2, Issue 2 (4-2012)
Abstract
Biofuels are playing important role in recent decades as substitutes for petro diesel. Biodiesel derived from vegetable
oils are found to give comparable performance and emission characteristics. In this paper a comparative study has been
done between two fuels combinations i.e. jatropha and castor. The biodiesel was prepared from neat oils and blends of
biodiesel (up till 20%) were prepared with diesel. Produced blends were tested for their use as a substitute fuel for
diesel in a single cylinder diesel engine. On the observed data for both the fuels, Student t statistical test was applied.
The values for fuel consumption calculated for t were 0.088 for jatropha oil methyl ester (JOME) and 0.44 for castor
oil methyl ester (COME) blends. Similarly for emission characteristics the values for CO2, CO, NOx calculated for t
were 2.94, -4.781, 2.83 for COME and 5.48, -2.91 and 4.24 for JOME respectively. The values concluded that there
is no effect of fuel type on fuel consumption up till 20 percent biodiesel blended fuel with respect to performance and
emission characteristics.
S. Sanaye, M. Dehghandokht,
Volume 2, Issue 2 (4-2012)
Abstract
In this paper, mini-channel type evaporator which is new in mobile air conditioning (MAC) or automotive air
conditioning (AAC) systems is thermally modeled. The performance of mini-channel evaporator is also compared with
the laminated evaporator which is being currently used in automotive industries. The mini-channel evaporator was
constructed of two rows of parallel flow mini-channel tubes with inlet and outlet headers. The numerical results of
modeling the laminated and mini-channel evaporators validated with the corresponding experimental data which was
obtained from experiments performed on mobile air conditioning system in calorimeter test bench. The comparison of
modeling results of two evaporators showed good agreement with experimental data. The performance of laminated
and mini-channel evaporators were also compared under various operating conditions. The mini-channel evaporator
had higher cooling capacity (7.2%) and higher refrigerant pressure drop (45%) in comparison with the corresponding
values in laminated evaporator assuming the same external geometry. The outlet air temperature and enthalpy of minichannel
evaporator was also lower, 11% and 8% respectively, than that for laminated evaporator. This cause to reduce
the time period as well as power/fuel consumption for reaching the comfortable cabin temperature.
M. Shahab, M. Moavenian,
Volume 2, Issue 2 (4-2012)
Abstract
Vehicle driveline system and its working accuracy play an important role in the performance of car. The purpose of
this study is to provide an appropriate mechanism for investigating, identifying and determining the position and size
of defects in the vehicle power transmission system. This is based on the patterns of the residual signal, obtained from
a simulated model of the system. Neuro-fuzzy networks have been used in diagnosis of defects because of its specific
advantages and capabilities in pattern recognition. Simulation results demonstrate that the resulting fault detection
system is able to properly locate the fault types under all test conditions, and is sensitive also to fault size. Test and
simulation results using MATLAB software is given at the end.
A. Mohebbi, S. Jafarmadar, J. Pashae,
Volume 2, Issue 2 (4-2012)
Abstract
Nitrogen oxides (NOx) contribute to a wide range of environmental effects including the formation of acid rain and
destroy ozone layer. In-cylinder high temperature flame and high oxygen concentration are the parameters which affect
the NOx emissions. The EGR system is a very effective way for reducing NOx emission from a diesel engine (via
reduction of these parameters), particularly at the high load of engine operation condition. In this study, the influence
of EGR on diesel engine combustion, NOx/PM emissions, brake specific fuel consumption (BSFC), engine thermal
efficiency, cylinder pressure and heat release rate (HRR) are analyzed and presented. The experiments have been
conducted on a turbocharged DI diesel engine under full load condition at two different injection timings in order to
distinguish and quantify some effects of Hot and Cooled EGR with various rates on the engine parameters.
Experimental results showed that increase of EGR rate has a negative effect on air-fuel ratio. For a premixed
combustion at constant boost pressure, ignition delay is increased leading to retardation of all combustion process, a
low HRR peak and reduce of in-cylinder peak temperature. Using of Hot EGR reduces NOX emissions whereas PM
emissions are increased. The advance of injection timing resulted in the reduction PM while both NOX emissions and
fuel consumption were increased. The use of cooled EGR was more effective compared to the hot EGR. As a result,
the EGR temperature has no significant impact on NOx emissions. With increasing EGR rate, unequal EGR
distribution was increased in inlet port of cylinders while the reducing EGR temperature (cooled EGR) improved its
distribution among the engine cylinders and decreased the EGR cylinder-to-cylinder variations.
M. A. Saeedi, R. Kazemi, M. Rafat, A. H. Pasdar,
Volume 2, Issue 2 (4-2012)
Abstract
In this paper, a complete model of an electro hydraulic driven dry clutch along with its
performance evaluation has elucidated. Through precision modeling, a complete nonlinear
physical and full order sketch of clutch has drawn. Ultimate nonlinearities existent in the
system prohibits it from being controlled by conventional linear control algorithms and to
compensate the behavior of the system mainly during gearshift procedure, a nonlinear control
program has been developed and tested. A unique approach to estimating clamp force has been
adopted which makes the system comparable to a real world and full-physical one. Based on
this type of modeling, the control approach is a true and feasible, ready-to-implement program
which is based only on reality. The clutch model has been validated against experiments and
great agreement has been attained since, every fine point has been taken into account and
nothing is out of representation unless it is not crucial to system performance. The nonlinear
control program does the control task very well and administrates the system in the desired
trajectory.
J. Marzbanrad, M. Alahyari Beyg,
Volume 2, Issue 2 (4-2012)
Abstract
In this paper, the acoustic environment in a vehicle cabin under the influence of highfrequencies aerodynamic sources has been studied. Some panels on the windshield, the roof, the doors, the front pillars, and the floor of a vehicle simulated as input source of noise when the car is moving at high speed, i.e. 112 km/h. The status of vehicle cabin in each of these modes has been studied and compared to each other. There are some methods to simulate acoustic behavior of a vehicle cavity such as Finite Elements or Statistical Energy Analysis methods. A brief overview for Statistical Energy Analysis (SAE) is stated. In this study, the statistical energy method is used for determination of acoustic analysis. Auto SEA software is used to simulate and estimate the amount of sound pressure level. In addition, sound pressure formulation presented and used for comparison in vehicle cabin points and with experimental results for validation. Also, considering viscoelastic materials, a common form of material nonbinding panel has determined. The result shows that the roof is the most important panel in acoustic analysis under influence of aerodynamic sources. Accordingly, this panel has more effectiveness in optimization to control sound pressure level in a vehicle cabin. In addition, the amount of reduction in sound pressure level (SPL) in the cabin with viscoelastic material is presented as it could diminish the vibration of plates. In addition, the effect of using acoustic glasses is presented. Finally, the SPL effect of passenger position including front and rear is investigated and compared
S.m. Shariatmadar, M. Manteghi, M. Tajdari,
Volume 2, Issue 2 (4-2012)
Abstract
Non-linear characteristic of tire forces is the main cause of vehicle lateral dynamics instability,
while direct yaw moment control is an effective method to recover the vehicle stability. In this
paper, an optimal linear quadratic regulator (LQR) controller for roll-yaw dynamics to
articulated heavy vehicles is developed. For this purpose, the equations of motion obtained by
the MATLAB software are coded and then a control law is introduced by minimizing the local
differences between the predicted and the desired responses. The influence of some parameters
such as the anti roll bar, change the parameters of the suspension system and track wide in
articulated heavy vehicles stability has been studied. The simulation results show that the
vehicle stability can be remarkably improved when the optimal linear controller is applied
