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Showing 7 results for Jafari

M. M. Tehrani, M. R. Hairi-Yazdi, Ba. Haghpanah-Jahromi, V. Esfahanian, M. Amiri, A. R. Jafari,
Volume 1, Issue 2 (6-2011)
Abstract

In this paper, an adaptive rule based controller for an anti-lock regenerative braking system (ARBS) of a series hybrid electric bus (SHEB) has been proposed. The proposed controller integrates the regenerative braking and wheel anti-lock functions by controlling the electric motor of the hybrid vehicle, without using any conventional mechanical anti-lock braking system. The performance of the proposed system is evaluated by a comprehensive vehicle dynamics model in MATLAB/Simulink. Using the designed ARBS, the braking and regenerative performances of SHEB have significantly improved in slippery roads while the slip ratios are kept between 0.15 and 0.20.
D. Younesian, A.a. Jafari, R. Serajian,
Volume 1, Issue 3 (5-2011)
Abstract

Nonlinear hunting speeds of railway vehicles running on a tangent track are analytically obtained using Hopf bifurcation theory in this paper. The railway vehicle model consists of nonlinear primary yaw dampers, nonlinear flange contact stiffness as well as the clearance between the wheel flange and rail tread. Linear and nonlinear critical speeds are obtained using Bogoliubov method. A comprehensive parametric study is then carried out and effects of different parameters like the magnitudes of lateral clearance, damping values, wheel radius, bogie mass, lateral stiffness and the track gauge on linear and nonlinear hunting speeds are investigated.
M. Hakimollahi, S. G. Jalali Naini, M. Bagherpour, S. Jafari, A. Shahmoradi,
Volume 2, Issue 4 (10-2012)
Abstract

In recent years, the balanced score card (BSC) has been the focus of considerable methodology for strategic cost management in management accounting area since it was originally proposed by Kaplan ,R.S. and Norton, D.P. in 1992. BSC is an approach to performance measurement based on both financial and nonfinancial information from four perspectives which are called financial, customer, internal business process, and learning and growth, in order to balance the traditional financial performance system by several grouping of performance measures: short-term and long-term, internal and external, and current and future. Over time, it has been developed to a strategic management system from a comprehensive performance measure, and used in many organizations such as business, hospital, and autonomy in many countries. In this paper, we propose a general model based on BSC by introducing fuzzy inference mechanism. From this, specialists’ knowledge and experience can be effectively reflected during the construction of the practical model. Then we illustrate a practical example for an Automotive Manufacturing Co.
B. Jafari, D. Domiri Ganji,
Volume 3, Issue 2 (6-2013)
Abstract

Air pollution is one of the major issues about the diesel engines in todays' world. It is a special concern in those areas that have difficulty meeting health-based outdoor air quality standards. Natural gas has low emission and resource abundance and also conventional compression ignition engine can be easily converted to a dual fuel mode to use natural gas as main fuel and diesel as pilot injection. The main object of this work is to investigate the effect of number of injector nozzle hole on the combustion and exhaust emission in a gas engine ignited with diesel fuel. We use one and three-dimensional simulation in parallel way in order to analyze the performance and combustion process of a dual fuel engine. The experimental results have also reported and compared with the simulated data.
A. Jafari, Sh. Azadi, M. Samadian,
Volume 3, Issue 3 (9-2013)
Abstract

The directional response and roll stability characteristics of a partly filled tractor semi-trailer vehicle, with cylindrical tank, are investigated in various maneuvers. The dynamic interaction of liquid cargo with the tractor semi-trailer vehicle is also evaluated by integrating a dynamic slosh model of the partly filled tank with five-degrees-of-freedom of a tractor semi-trailer tank model. The dynamic fluid slosh within the tank is modeled using three-dimensional Navier-Stokes equations, coupled with volume-of-fluid equations and analysed using the FLUENT software. The coupled tank-vehicle model is subsequently analysed to determine the roll stability characteristics for different maneuvers. The results showed the interaction of fluid slosh with vehicle's dynamic. Another findings of this investigation also revealed that the roll stability of a tractor semi-trailer tank carrying liquid was highly affected by fluid sloshing and caused degradation of roll stability in comparison with vehicle carrying rigid cargo.
M. Fathian, A.r. Jafarian-Moghaddam , M. Yaghini ,
Volume 4, Issue 4 (12-2014)
Abstract

Vehicular ad-hoc network (VANET) is an important component of intelligent transportation systems, in which vehicles are equipped with on-board computing and communication devices which enable vehicle-to-vehicle communication. Consequently, with regard to larger communication due to the greater number of vehicles, stability of connectivity would be a challenging problem. Clustering technique as one of the most important data mining techniques is a possible method that can improve the stability of connectivity in VANET. Stable communication within a VANET leads to enhanced driver safety and better traffic management. Therefore, this paper presented a novel clustering algorithm based on ant system-based algorithm called IASC in order to provide a fast clustering algorithm with high accuracy and improve the stability of VANET topology. A comparative study was proposed to analogize the results of the proposed algorithm with six VANET clustering algorithms in the literature which were taken as benchmarks. Results revealed improvement in stability and overhead on VANET.
Dr Behrooz Mashhadi, Dr Amirhasan Kakaee, Mr Ahmad Jafari,
Volume 9, Issue 1 (3-2019)
Abstract

In this research, a high-temperature Rankin cycle (HTRC) with two-stage pumping is presented and investigated. In this cycle, two different pressures and mass flow rates in the HTRC result in two advantages. First, the possibility of direct recovery from the engine block by working fluid of water, which is a low quality waste heat source, is created in a HTRC. Secondly, by doing this, the mean effective temperature of heat addition increases, and hence the efficiency of the Rankin cycle also improves.
The proposed cycle was examined with the thermodynamic model. The results showed that in a HTRC with a two-stage pumping with an increase of 8% in the mean effective temperature of heat addition, the cycle efficiency is slightly improved. Although the operational work obtained from the waste heat recovery from the engine cooling system was insignificant, the effect of the innovation on the recovery from the exhaust was significant. The innovation seems not economical for this low produced energy. However, it should be said that although the effect of the innovation on the increase of the recovery cycle efficiency is low, the changes that must be implemented in the system are also low. 

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