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Showing 37 results for Modeling

M. H. Askari, S. M. Hoseinalipour, S. A. Jazayeri, M. Baghsheikhi,
Volume 1, Issue 2 (6-2011)
Abstract

The HCCI combustion process is initiated due to auto-ignition of fuel/air mixture which is dominated by chemical kinetics and therefore fuel composition has a significant effect on engine operation and a detailed reaction mechanism is essential to analysis HCCI combustion. A single zone-model permits to have a detailed chemical kinetics modeling for practical fuels. In this study a single-zone thermodynamic model with detail chemical mechanism is developed to investigate the effect of hydrogen addition to natural gas in a homogeneous charge compression ignition combustion and to analyze the performance and emissions of the HCCI engine. The effect of five different percentage of hydrogen added to natural gas ranging from 0 to 40 on HCCI combustion is investigated in this study. The results indicate that by increasing hydrogen portion in intake mixture, start of combustion advances and maximum temperature increase, but increasing in maximum pressure is negligible. Carbon’s included emissions such as Co, Co2 and unburned hydrocarbons decreases by increasing of hydrogen, and also, specific fuel consumption decreases. The result shows that hydrogen improves combustion characteristics of natural gas in an HCCI engine and leads to better performance and less emissions.
S. Sanaye, M. Dehghandokht,
Volume 1, Issue 3 (5-2011)
Abstract

Thermal modeling of an automotive cabin was performed in this paper to predict the inside cabin air temperature. To implement this task, thermal and ventilation loads were estimated and the mass and energy balance conservation equations for dry air and water vapor with considering a new parameter (air circulation ratio) as well as the balance equations of internal components of a cabin were derived and solved simultaneously. The performance of the proposed thermal modeling of a cabin was compared with the data collected from hot room experimental tests. These tests were run for various design parameters such as evaporating cooling load and cabin size (air volume inside cabin). The comparison of experimental and numerical results showed a good agreement. Parametric analysis with three parameters namely, vehicle speed, number of passengers, and A/C air mass flow rate was performed to investigate the effects of these parameters on cabin air temperature.
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.
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. 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.
A. Khalkhali, S. Samareh Mousavi,
Volume 2, Issue 3 (7-2012)
Abstract

In order to reduce both the weight of vehicles and the damage of occupants in a crash event simultaneously, it is necessary to perform a multi-objective optimization of the automotive energy absorbing components. In this paper, axial impact crushing behavior of the aluminum foam-filled thin-walled tubes are studied by the finite element method using commercial software ABAQUS. Comparison of the present simulation results with the results of the experiments reported in the previous works indicated the validity of the numerical analyses. A meta-model based on the feed-forward artificial neural networks are then obtained for modeling of both the absorbed energy (E) and the peak crushing force (Fmax) with respect to design variables using those data obtained from the finite element modeling. Using such obtained neural network models, a modified multi-objective GA is used for the Pareto-based optimization of the aluminum foam-filled thinwalled tubes considering three conflicting objectives such as energy absorption, weight of structure, and peak crushing force.


M. H. Shojaeefard, M. M. Etghani, M. Tahani, M. Akbari,
Volume 2, Issue 4 (10-2012)
Abstract

In this study the performance and emissions characteristics of a heavy-duty, direct injection, Compression ignition (CI) engine which is specialized in agriculture, have been investigated experimentally. For this aim, the influence of injection timing, load, engine speed on power, brake specific fuel consumption (BSFC), peak pressure (PP), nitrogen oxides (NOx), carbon dioxide (CO2), Carbon monoxide (CO), hydrocarbon (HC) and Soot emissions has been considered. The tests were performed at various injection timings, loads and speeds. It is used artificial neural network (ANN) for predicting and modeling the engine performance and emission. Multi-objective optimization with respect to engine emissions level and engine power was used in order to deter mine the optimum load, speed and injection timing. For this goal, a fast and elitist non-dominated sorting genetic algorithm II (NSGA II) was applied to obtain maximum engine power with minimum total exhaust emissions as a two objective functions.


A. Ghaffari, A. Khodayari, S. Arvin, F. Alimardani,
Volume 2, Issue 4 (10-2012)
Abstract

The lane change maneuver is among the most popular driving behaviors. It is also the basic element of important maneuvers like overtaking maneuver. Therefore, it is chosen as the focus of this study and novel multi-input multi-output adaptive neuro-fuzzy inference system models (MANFIS) are proposed for this behavior. These models are able to simulate and predict the future behavior of a Driver-Vehicle-Unit in the lane change maneuver for various time delays. To design these models, the lane change maneuvers are extracted from the real traffic datasets. But, before extracting these maneuvers, several conditions are defined which assure the extraction of only those lane change maneuvers that have a smooth and uniform trajectory. Using the field data, the outputs of the MANFIS models are validated and compared with the real traffic data. In addition, the result of these models is compared with the result of other trajectory models. This comparison provides a better chance to analyze the performance of these models. The simulation results show that these models have a very close compatibility with the field data and reflect the situation of the traffic flow in a more realistic way.
S. R. Das, D. Dhupa, A. Kumar,
Volume 3, Issue 1 (3-2013)
Abstract

Turning of hardened steels using a single point cutting tool has replaced the cylindrical grinding now as it offers attractive benefits in terms of lower equipment costs, shorter set up time, fewer process setups, higher material removal rate, better surface quality and elimination of cutting fluids compared to cylindrical grinding. In order to obtain desired surface quality by machining, proper machining parameters selection is essential. This can be achieved by improving quality and productivity in metal cutting industries. The present study is to investigate the effect of machining parameters such as cutting speed, feed and depth of cut on surface roughness during dry turning of hardened AISI 4340 steel with CVD (TiN+TiCN+Al2O3+ZrCN) multilayer coated carbide inserts. A full factorial design of experiment is selected for experimental planning and the analysis of variance (ANOVA) has been employed to analyze the significant machining parameters on surface roughness during turning. The results showed that feed (60.85%) is the most influencing parameter followed by cutting speed (24.6%) at 95% confidence level. And the two-level interactions of feed-cutting speed (F*V), depth of cut-feed (D*F) and depth of cutcutting speed (D*V) are found the significant effects on surface roughness in this turning process. Moreover, the relationship between the machining parameters and performance measure i.e. surface roughness has been modeled using multiple regression analysis.
H. Pashazadeh, A. Masoumi, J. Teimournezhad,
Volume 3, Issue 1 (3-2013)
Abstract

The objective of this study was to develop a numerical model for the prediction of temperature distribution, effective plastic strain distribution, and especially material flow in friction stir welding of copper plates. The DEFORM-3D software was used by incorporating a lagrangian incremental formulation. Threedimensional results of the material flow pattern which were extracted using the point tracking are in good agreement with the experiment. It was shown that the main part of material flow occurs near the top surface. Material near the top surface at the behind of tool stretches from retreating side towards advancing side which leads to non-symmetrical shape of the stir zone. The stir zone shape in FSW of copper alloys, which was predicted by simulation, does not lean completely towards any sides of welding line.
A. Ghaffari, A. Khodayari, F. Alimardani, H. Sadati,
Volume 3, Issue 2 (6-2013)
Abstract

Overtaking a slow lead vehicle is a complex maneuver because of the variety of overtaking conditions and driver behavior. In this study, two novel prediction models for overtaking behavior are proposed. These models are derived based on multi-input multi-output adaptive neuro-fuzzy inference system (MANFIS). They are validated at microscopic level and are able to simulate and predict the future behavior of the overtaking vehicle in real traffic flow. In these models, the kinematic features of Driver-Vehicle-Units (DVUs) such as distance, velocity, and acceleration are used. Unlike the previous models, where some variables of the two involved vehicles are considered to be constant, in this paper, instantaneous values of the variables are considered. The first model predicts the future value of the longitudinal acceleration and the movement angle of the overtaking vehicle. The other model predicts the overtaking trajectory for the overtaking vehicle. The second model is designed for two different vehicle classes: motorcycles and autos. Also, the result of the trajectory prediction model is compared with the result of other models. This comparison provides a better chance to analyze the performance of this model. Using the field data, the outputs of the MANFIS models are validated and compared with the real traffic dataset. The simulation results show that these two MANFIS models have a very close compatibility with the field data and reflect the situation of the traffic flow in a more realistic way. These models can be used for all types of drivers and vehicles and also in other roads and are not limited to certain types of situations. The proposed models can be employed in ITS applications and the like.
S. Jafarmadar, M. Khanbabazadeh,
Volume 3, Issue 2 (6-2013)
Abstract

In the present work, multidimensional modeling of open-cycle process of OM355 engine was developed. Calculations for computational mesh were carried out. The results of the model were validated by experimentally measured in-cylinder pressure and the good agreement between calculations and measurements approved the trustworthy of numerical code. Results included pressure, temperature, emission and Rate of heat release diagrams were represented for the full cycle. Furthermore local flow field velocity vectors were indicated. The results show the importance of open-cycle simulations in automotive researches.
A. R. Noorpoor,
Volume 3, Issue 3 (9-2013)
Abstract

Oil pump in diesel engine has significant effect on energy consumption and environment pollution. In this paper, the modeling and simulation of a gear oil pump used in a diesel engine and its fluid flow analysis by a solver has been explained. Also the optimization and redesign of it has been discussed and then the outcomes have been compared with the experimental and previous results. The type of this oil pump is external gear pump with involute tooth profile, so we need to use the gears with the minimum number of tooth to optimize the pump performance and getting the optimum displacement volume rate of it. While the engaged gears of the pump rotating together, the intersection between them changes in time. So their boundaries should be considered as movable. The strategy used here consist in using dynamic meshes, dividing a tooth rotating cycle into a certain number of time steps and investigating the flow and getting the results for each time steps.
B. Soleimani, M. M. Jalili,
Volume 3, Issue 3 (9-2013)
Abstract

Wheel/rail contact simulation is one of the most complicated problems in the modeling of railway vehicles. The wheel/rail interaction plays a unique role in rail vehicle dynamics. In this paper, the dynamic response of the wheel on irregular rail track is analyzed with analytical approach using the method of Multiple Scales (MMS). The Hertzian contact theory is used to obtain the relationship between normal contact force and the displacement of the mass center of the wheel. Analytical approach is expanded for performance of train’s wheel travelling on the rail. To validate the method presented in this paper, responses of the model using MMS method are compared with the results obtained from the Runge–Kutta numerical solution. Finally effects of the wheelset preload on response frequency have been studied.
M. Esfahanian, A. Mahmoodian, M. Amiri, M. Masih Tehrani, H. Nehzati, M. Hejabi, A. Manteghi,
Volume 3, Issue 4 (12-2013)
Abstract

In the present study, a model of a large Lithium Polymer (Li-Po) battery for use in the simulation of Hybrid Electric Vehicles (HEVs) is developed. To attain this goal, an Equivalent Circuit (EC) consisting of a series resistor and two RC parallel networks is considered. The accuracy and the response time of the model for use in an HEV simulator are studied. The battery parameters identification and model validation tests are performed in low current with a good accuracy. Similar test process is implemented in high current for another cell and the simulation is verified with experimental results. The validation tests confirm the accuracy of the model for use in HEV simulator. Finally, the battery model is used to model a Vehicle, Fuel and Environment Research Institute (VFERI) hybrid electric city bus using ADVISOR software and its compatibility with other components of the vehicle simulator are demonstrated in a drive cycle test.
A. Amini, M. Mirzaei, R. Khoshbakhti Saray,
Volume 3, Issue 4 (12-2013)
Abstract

In spark ignition (SI) engines, the accurate control of air fuel ratio (AFR) in the stoichiometric value is required to reduce emission and fuel consumption. The wide operating range, the inherent nonlinearities and the modeling uncertainties of the engine system are the main difficulties arising in the design of AFR controller. In this paper, an optimization-based nonlinear control law is analytically developed for the injected fuel mass flow using the prediction of air fuel ratio response from a mean value engine model. The controller accuracy is more increased without chattering by appending the integral feedback technique to the design method. The simulation studies are carried out by applying severe changes in the throttle body angle to evaluate the performance of the proposed controller with and without integral feedback. The results show that the proposed controller is more effective than the conventional sliding mode controller in regulating the AFR without chattering.
A. Hemati, M. Tajdari, A.r. Khoogar,
Volume 3, Issue 4 (12-2013)
Abstract

This paper presents a reduce roll vibration of the full vehicle model with passive suspension systems using vibration absorber to change the dynamic system matrix stat’s eigenvalue. Since using the controller system has been splurged and required to energy consuming, in this research the vehicle body roll vibration has been reduced and supplied vehicle stability using a vibration absorber for the passive suspension system. In this paper a new manner is introduced to reduce body roll angle and body's roll acceleration. The transverse instability in the independent suspension is a main problem, roll angle decreased transverse stability, that it has been reduced using vibration absorber. The optimal value of vibration absorber’s mass, spring and damping coefficient has been determined by using genetic algorithms (GA) to achieve developed roll angle behavior. The main purpose of this article is to reduce vehicle body roll angle that has been acquired using vibration absorber, this manner is better than other ways for roll reduction of vehicle body because it has done without any energy consuming.
A. Khalkhali, M. Afroosheh, M.r. Seyedi,
Volume 4, Issue 1 (3-2014)
Abstract

In this paper, numerical simulation of FRP composite cylinder tubes progressive crushing processes is conducted using LS-Dyna. Details on the numerical modeling strategy are given and discussed. It is found that triggers introduced in the numerical simulation can effectively model the bevel trigger at the end of the tubular specimens. It is also found that two-layer finite element model based on the TsaiWu failure criteria is effective in representing the crushing failure mode of the tubular composite specimens and energy absorption characteristics. Employing GEvoM software, two meta-models are then obtained for modeling of both the absorbed energy (E) and the peak crushing force (Fmax) with respect to geometrical design variables using input output data obtained from the finite element modeling. Comparison between obtained meta-models and numerical results in both of training and testing sets show good approximation by using obtained polynomial models.


Gh.h Payeganeh, M. Esfahanian, S. Pakdel Bonab,
Volume 4, Issue 2 (6-2014)
Abstract

In the present paper, the idea of braking energy regeneration and reusing that energy during acceleration for a refuse truck is comprehended. According to their driving cycle, the refuse trucks have a good potential for braking energy regeneration. On the other hand, hydraulic hybrid is a powertrain with high power density which is appropriate for energy regeneration. In the primary stage of this issue, the hydraulic hybrid propulsion system is designed with intention of regenerating the maximum possible kinetic energy during the refuse truck braking mode. At this stage, a non-fuzzy rule-based control strategy is applied to manage the energy flow in the hybrid powertrain. After that, the powertrain of the Axor 1828 truck and the elements of the hydraulic powertrain are modeled in MATLAB/Simulink. The modeling is performed considering the efficiencies of the powertrain elements. In the last part of the paper, a fuzzy control strategy is designed and modeled to improve the fuel consumption of the truck with hybrid powertrain. In order to see the usefulness of the designed hybrid powertrain, several simulations are organized on the vehicle model in Simulink. The driving cycle for refuse truck in Tehran is used for performing the simulations. The results state indicated that using the hydraulic hybrid powertrain decreased the fuel consumption of the refuse truck by 7 percent. In addition, this amount of reduction was improved by implementing the fuzzy control strategy. The decrease in fuel consumption was due to the regenerating of the braking energy up to 50 percent.
M. Namjoo, H. Golbakhshi,
Volume 4, Issue 3 (9-2014)
Abstract

The natural frequencies and mode shapes of pneumatic tires are predicted using a geometrically accurate, three-dimensional finite element modeling. Tire rubber materials and cord layers are represented independently using “shell element” available in COSMOS. The effects of some physical parameters such as the inflation pressure tread pattern, thickness of belts and ply angles to the natural frequencies of tires are investigated. By imposing equivalent centrifugal forces, the effect of translational speed on vibrating behavior of the tire is also studied in this work. Comparisons of numerical and experimental results are given to show the validity of the proposed model.

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