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Showing 5 results for Ghasemi

M. Eftekhar, A. Keshavarz, A. Ghasemian, J. Mahdavinia,
Volume 3, Issue 1 (3-2013)

Running the industrial components at a proper temperature is always a big challenge for engineers. Internal combustion engines are among these components in which temperature plays a big role in their performance and emissions. With the development of new technology in the fields of ‘nano-materials’ and ‘nano-fluids’, it seems very promising to use this technology as a coolant in the internal combustion engines. In this study, a nano-fluid (Al2O3-Water/Ethylene Glycol (EG)) is used as an engine coolant along with an optimized heat exchanger to reduce the warm-up timing. The effect of nano-fluid concentration is considered here by using their corresponding governing equations, such as momentum and energy. The engine coolant thermal behavior calculation is carried out based on the lumped method. The obtained results indicated that using different percentage of nano-fluid mixtures (by volume), such as Al2O3- Water/EG as engine coolant enhances the heat transfer coefficient and reduces the warm-up timing which, in turn, results in reduced emissions and fuel consumption.
A. Ghasemian, A. Keshavarz, H. Sotodeh,
Volume 4, Issue 1 (3-2014)

The subjects of heat transfer and cooling system are very important topics in the Internal Combustion Engines (ICE). In modern cooling systems, low weight, small size and high compactness are the critical designing criteria that requires heat transfer enhancement. Boiling phenomenon which is occurred in the water jacket of the ICE is one of the methods to increase heat transfer in the coolant system of an ICE. A research has been shown that parameters such as material, temperature, and roughness of the heated surface have direct effect on the rate of heat transfer in a boiling phenomenon. In this paper the potential of boiling phenomenon and the effect of the surface roughness on the amount of heat flux removed by the coolant flow in the engine water jacket is investigated experimentally. For this purpose the experiments was carried out in three different flow velocities and also three different surface roughnesses. Results show that the boiling and roughness of a hot surface will increase the heat removal significantly.
Dr Hossein Chehardoli, Dr Ali Ghasemi, Mr Mohammad Daneshyian,
Volume 10, Issue 4 (12-2020)

A new safe optimal consensus procedure is presented to guarantee the asymptotic and string stability as well as crash avoidance of large-scale non-identical traffic flow. Since time delay is an inherent characteristic of physical actuators and sensors, measurement delay and lags are involved in the upper level control structure. A third-order linear model is employed to define the 1-D motion of each automated vehicle (AV) and the constant time headway plan is employed to regulate the inter-AV distance. It is assumed that the network structure is decentralized look ahead (DLA) and each AV has access to relative position and velocity regarding with the front AV. A linear control law is introduced for each AV and by performing the stability analysis in frequency domain, the necessary conditions guaranteeing string stability and crash avoidance for large-scale traffic flow are derived. Afterwards, to calculate the optimal control parameters guaranteeing the best performance, an objective function combining all mentioned conditions as well as maximum overshoot, settling time and stability margin is introduced. The genetic algorithm (GA) technique is employed to optimize the presented objective function and obtain the optimal control parameters. Various numerical results are proposed to demonstrate the efficiency of this method.
Seyyed Hamed Tabatabaei, Saeed Moradi Haghighi, Amirhossein Kiani, Kasra Ghasemian,
Volume 11, Issue 2 (6-2021)

In this paper, an optimized insulator for sound packaging of the vehicle dash panel is proposed. The combination of the micro perforated panel and porous layers has been selected to insulate the dash panel of a vehicle.  The main advantages of the mentioned combination are light weight and various tunable parameters in comparison with other insulators. These provide significant flexibility to achieve an optimal performance for the noise attenuation of the vehicle cabin. Therefore, the parameters of the selected sound package have been optimized in order to achieve suitable sound absorption in a selected frequency range. Furthermore, the Genetic Algorithm (GA) is used to optimize the parameters. It can achieve more reliable and more accurate outcomes compared to the conventional method.  Full vehicle SEA (Statistical Energy Analysis) simulations are used to evaluate the optimized sound package. The results indicate that the optimized concept has maximum sound absorption capability.  Consequently, the proposed sound package improves the vehicle's engine noise reduction by 5 dB in comparison with un-optimized sample in mid and high frequency ranges.
Pouyan Namdar, Hamed Saeidi Googarchin, Seyed Hooman Ghasemi,
Volume 12, Issue 1 (3-2022)

In this paper, mechanical properties of welded single lap joints of pure aluminum sheets produced by severe plastic deformation (SPD) are considered. SPD in form of a large pre-strain was imposed to aluminum sheets through the constrained groove pressing (CGP) process. Furthermore, CGPed specimens are joined using the resistance spot welding (RSW) method. Welding time and force are maintained evenly. Welding current is raised until ideal failure mode is observed. Finally, mechanical properties of fusion zone, heat affected zone (HAZ) and base metal of welded SPDed specimens are derived. The results show that by increasing the pre-strain in specimens, an improvement in yield strength, ultimate tensile strength, load carrying capacity, maximum displacement before failure and nugget diameter is observed. Furthermore, sensitivity of these parameters to CGP pass number is considered. Finally, it has been shown that fusion zone and HAZ hardness values can increase by increasing the CGP pass number.

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