Precise speed control of an Interior Permanent Magnet Synchronous Motor (IPMSM) drive becomes a complex issue due to complex coupling among its winding currents and the rotor speed as well as the nonlinear nature of the developed torque. The system nonlinearity becomes severe when the IPMSM drive operates in the field weakening region. The main purpose of this paper is to present the implementation of an emotional controller for flux weakening speed control of an IPMSM drive. The proposed controller is called Brain Emotional Learning Based Intelligent Controller (BELBIC) and is a computational model of emotional processing mechanism in the brain. The effectiveness of the proposed BELBIC controller-based IPMSM drive is verified by simulation results at different operating conditions. Moreover, control regimes such as Maximum Torque per Ampere (MTPA) control and Flux Weakening (FW) control as well as voltage and current constraints have been successfully applied. The results prove BELBIC's perfect control characteristics, fast response, simple implementation and adaptability to speed, load and parameter changes. © 2011 IEEE.
International Journal of Advanced Manufacturing Technology (14333015)(5-8)
Data envelopment analysis (DEA) is an important managerial tool for evaluating and improving the performance of decision making units. The existing DEA models are mostly limited to static environment using crisp data and are time-consuming and also have weak discriminating power. The aim of this work is to introduce a new fuzzy dynamic DEA model with missing values, which benefits from strengths of multi-objective modeling to overcome weakness and drawbacks of the classic DEA models. To check for quality and accuracy of the proposed model, this paper offers a comparative study to compare the discriminating power and computational efforts of the model with two problems in the literature taken as benchmarks. Also, this paper presents a real application of the fuzzy dynamic DEA model for assessing and ranking the level of performance for 56 railways around the globe using real data gathered from credible sources. The numerical case illustrates the model and the result may be used by railways to improve their performance efficiency compared to the best in the sample. Results for the comparative study and the real case reveal significant improvement in computational time and discriminating power. © Springer-Verlag London Limited 2011.
Unbalanced line currents cause unbalanced voltage drops on the three phases of the supply system. Consequently, the voltage system within the supply network will become unbalanced. Voltage unbalance has different detrimental effects in electrical power systems, such as the growth of losses in drive systems and adjustable speed drives, supplementary heating, line-current unbalance, derating, torque pulsation, mechanical stresses, etc. This paper makes an effort to have a comprehensive analysis of the effects of different connection types of three phase transformers on voltage unbalance propagation in distribution networks. The indices of voltage unbalance factor (VUF) and current unbalance factor (IUF) are used in this paper to evaluate the unbalance propagation. These indices are acquired utilizing symmetrical component theory on three phase voltages and currents earned through the system impedance matrix. © 2012 IEEE.
Precise speed control of a Linear Induction Motor (LIM) drive becomes a complex issue due to the end effect phenomena which results in the weakening of the airgap flux and thrust. The end effect becomes severe when the LIM drive operates at higher speeds. The main purpose of this paper is to present an accurate qd dynamic model of linear induction motor suitable for vector control and drive applications considering the end effects. In this model not only the magnetizing inductance is modified but also the series resistance reflecting the eddy current is considered in the series with the magnetizing branch in both q and d axes. Moreover, a corresponding indirect field oriented control (IFOC) scheme is suggested. The effectiveness of the proposed IFOC scheme based LIM drive is verified by simulation results at different operating conditions. In addition, a five-level Cascaded H-bridge (CHB) inverter with multiband hysteresis modulation has been successfully applied for drive performance improvements. The results prove that the proposed LIM model and its related IFOC scheme show more accurate and comprehensive resultants and are therefore closer to the reality. Furthermore, utilization of the multilevel CHB inverter guarantees high drive performance and perfect control characteristics. ©2013 IEEE.
Ziari, H.,
Farahani h., H.Z.,
Goli, A.,
Galooyak, S.S. Petroleum Science and Technology (15322459)32(17)pp. 2102-2108
With the increase of traffic and consequently, and the loads applied on the roads, the need for a more durable pavement has a special significance. Therefore, the researchers have been seeking to improve the functional properties of bitumen and asphalt. For this reason, different materials have been used to modify these properties. In this study, the carbon nano tube (CNT) has been used as the modifier of bitumen performance. The use of this additive has improved both the classic (softening point, penetration degree, and so on) and performance (complex modulus, phase angle, fatigue parameter, rutting factor) properties of bitumen in comparison to the standard bitumen. © Taylor & Francis Group, LLC.
Galooyak, S.S.,
Palassi, M.,
Farahani h., H.Z.,
Goli, A. Petroleum and Coal (13377027)57(5)pp. 556-564
Carbon nanotubes are one of the most widely used Nanomaterial that have two main features of light-weight and high strength material for tensile, compressive, impact and thermal stresses. In this study, different contents of carbon nanotube are used for the modification of the conventional bitumen. For the samples prepared by the ultrasonic mixer, it is observed that the agglomerated Nano-materials are peeled off and uniformly dispersed in bitumen. Then classical experiments of bitumen, x ray analysis, and rheological tests using Dynamic Shear Rheometer, were conducted on the modified bitumen. Master curves are plotted, and the results depicted that addition of 1.2 wt% of carbon nanotubes to the bitu-men have improved rheological properties of bitumen at high and low temperature service, significantly. Also addition of Nanotube was increased the stiffness and reduced the phase angle of base bitumen.
Zalnezhad, H.,
Galooyak, S.S.,
Farahani h., H.Z.,
Goli, A. Petroleum and Coal (13377027)57(5)pp. 509-515
In this investigation, Nano-silica has been added in three percentages of 2%, 4% and 6% to improve the physical, rheological and mechanical properties of warm mix asphalt (WMA) containing 2% Sasobit. Several experiments have been conducted to evaluate and characterize the prepared samples. The results of investigations indicated that by increasing the percentage of Nano-silica, the qualification and functionality of the warm mix asphalt has been improved. Resilient modulus of WMA was slightly increased by increasing the Nano-silica content. So, the response of pavement to traffic loading at 25oC has been improved. Depth of cracking at a specified load cycles was decreased dramatically by adding the Nano-silica to the Sasobit WMA. At the same time, the stiffness of modified samples was much lower than control WMA. As a result, the Nano-silica extends the fatigue life of asphalt concrete. In addition, the wheel tracking test results depicted that the rutting depth have been reduced by increasing the Nano-silica content. Regarding the results of qualification tests, 4 wt% of Nano-silica was selected as the optimum content.
