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K.N.Toosi University of Technology
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A New Method for Multi-objective Optimal Design of Milling Parameters by Considering Chatter Vibrations

K.N.Toosi University of Technology-A. Sohani
Sharif University of Technology-E. Jafarzadeh, S. Khodaygan
Published 2019-05-13 by SAE International in United States
The desired milling process with high material removal rate (MRR) and low surface roughness of the product can be achieved only if machining chatter is absent. Incorporating chatter into the optimal selection of the machining parameters leads to a complex problem. Therefore, the approach of selecting conservative intervals for the machining parameters is usually employed instead. In this paper, a practical approach is proposed to specify the optimal machining parameters (depth of cut and spindle speed) in order to maximize MRR and minimize forced vibrations by considering machining chatter. Firstly, the worst-case scenario-based optimization problem in terms of the surface quality is solved to find the critical time at which maximal amplitude vibrations occur. Then, the time dependency of the problem is eliminated. Secondly, the multi-objective optimization is conducted to achieve the Pareto Optimal Front (POF). The Stability Lobe Diagram (SLD) is obtained independently through well-established analytical methods. Optimal machining parameters on the obtained POF are mapped into the SLD to represent optimal results for the cases at which machining chatter is absent. Finally, theseā€¦
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Effects of Spark Advance, A/F Ratio and Valve Timing on Emission and Performance Characteristics of Hydrogen Internal Combustion Engine

K.N.Toosi University of Technology-Farhad Salimi, Amir H. Shamekhi, Ali M. Pourkhesalian
Published 2009-04-20 by SAE International in United States
The use of hydrogen as an engine fuel has great potential for reducing exhaust emissions with the exception of a small amount of carbon containing emissions originating from the lubricating oil, NOx is the only pollutant emitted. In this paper by using a turbulent flame speed method, a quasi-dimensional thermodynamic model of an SI engine fueled with hydrogen is developed. In this work, simulation results are validated by experimental data. Then the effect of spark advance, A/F ratio and valve timing on emission and performance characteristics of the modeled engine has been investigated. Hence, remarkable effects in emission and performance characteristics observed. And the behavior of the modeled engine against the above parameters has been investigated and the reason of that is discussed.
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Automatic Driver Design and Longitudinal Dynamic Simulation for Passenger Cars

K.N.Toosi University of Technology-Mohammad Sharifirad, Seyed Ali Jazayeri
University of Alberta-Mahdi Shahbakhti
Published 2006-04-03 by SAE International in United States
The performance of a vehicle in driving cycles can be simulated by having appropriate models for vehicle and driver. In this paper a model of an automatic driver is designed to control the speed of vehicle. The power train, having manual transmission, is modeled and a speed tracking system is designed using the fuzzy logic. Satisfactory results are obtained when the simulation results are compared with those of the experimental tests for the vehicle in the ECE driving cycle.
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