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Golshannavaz S.,Islamic Azad University at Urmia
Journal of Intelligent and Fuzzy Systems

This research investigates the simultaneous allocation of optimally sited and sized distributed generation (DG) units along with the capacitor banks for power loss minimization in smart automated distribution systems (ADSs). Moreover, network reconfiguration as one of the salient features of ADSs realized by remotely controlled switches (RCSs) is proposed to be incorporated in the simultaneous optimal siting and sizing process of DGs and capacitors. As the structure of the system would vary in the solution process, all of the buses are considered as the candidate bus to connect DGs and capacitors. Several scenarios have been considered for concurrent allocation of DGs, capacitors and also reconfiguration in loss minimization problem to interrogate the performance of the proposed method. Binary genetic algorithm (BGA) is employed to simultaneously identify the optimal site and size of DGs and capacitors as well as the system structure. The proposed algorithm is effectively implemented and then validated on the well-known IEEE 33-bus standard distribution system. Assessing the different scenarios reveals that incorporating network reconfiguration in combined allocation of DG and capacitor, would result in superior power loss minimization and also affects the optimal site and size of DGs and capacitors. © 2014-IOS Press and the authors. All rights reserved. Source

Zavvari M.,Islamic Azad University at Urmia | Ahmadi V.,University of Tehran
IEEE Electron Device Letters

A single-photon detector based on an avalanche quantum dot IR photodetector is presented and designed for self-quenching and self-recovering operation at IR wavelength. The device consists of dot layers and resonant tunneling barriers in the absorption region. An additional layer, called the transient carrier buffer, is added to trap the backward holes. For an avalanche process, the accumulation of backward-traveling-avalanche-generated holes leads to a reduction in the electric field of the multiplication region and avalanche gain, and consequently, the detector is quenched. The detector is self-recovered by thermionic emission and tunneling currents. We study the self-quenching and self-recovery performance of the device. A detection efficiency of around 8% is obtained. © 1980-2012 IEEE. Source

Mostafaei H.,Islamic Azad University at Urmia | Meybodi M.R.,Amirkabir University of Technology
Wireless Personal Communications

In wireless sensor networks, when each target is covered by multiple sensors, we can schedule sensor nodes to monitor deployed targets in order to improve lifetime of network. In this paper, we propose an efficient scheduling method based on learning automata, in which each node is equipped with a learning automaton, which helps the node to select its proper state (active or sleep), at any given time. To study the performance of the proposed method, computer simulations are conducted. Results of these simulations show that the proposed scheduling method can better prolong the lifetime of the network in comparison to similar existing methods. © 2012 Springer Science+Business Media New York. Source

Jafarian A.,Islamic Azad University at Urmia
International Journal of Artificial Intelligence

Recently, there has been a considerable amount of interest and practice in solving many problems of several applied fields by fuzzy polynomials. In this paper, we intend to offer a new method for finding a solution of fully fuzzy polynomial with degree n, by using an artificial fuzzified feed-forward neural network. This neural net has the ability to get fuzzy vector as an input, and calculates its corresponding fuzzy output. It is clear that the input-output relation for each unit of fuzzy neural network is defined by the extension principle of Zadeh. In this work, a cost function is also defined for the level sets of fuzzy output and fuzzy target. Then we derive a learning algorithm from the cost function for adjusting three parameters of each triangular fuzzy weight. Consequently, our approach is illustrated by computer simulations on numerical examples. It is worthwhile to mention that, the application of this method in fluid mechanics has been shown by an example. © 2014 by IJAI CESER PUBLICATIONS. Source

Zavvari M.,Islamic Azad University at Urmia | Ahmadi V.,Tarbiat Modares University
Applied Optics

A novel design for a quantum dot infrared photodetector (QDIP) is proposed based on avalanche multiplication and is expected to be used as a single photon detector at mid-IR. A high field multiplication region is added to a conventional QDIP in separate absorption, charge, and multiplication structures to intensify incoming photocurrent generated in the absorption region. The absorption region of the photodetector consists of quantum dot layers that are responsible for absorption of mid-IR wavelengths. Because of higher operation voltages in gated-mode operation, resonant tunneling barriers are also included in the absorption region to prevent higher dark currents. The absorption region is designed for operation at ?8 ?m. During the gate pulse period, photo-generated electrons can trigger an avalanche and produce an output pulse. For this detector, the dark count rate (DCR) and single photon quantum efficiency (SPQE) are calculated at different temperatures. SPQE with peak of about 0. 3 for T50 K is obtained. For higher temperatures, about T 120 K, SPQE is very low due to the contribution of dark carriers generated in the quantum dot absorption region. © 2013 Optical Society of America. Source

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