2026-09-15T09:50:37+03:30 http://ijeee.iust.ac.ir/browse.php?mag_id=24&slc_lang=en&sid=1

24-383 2026-09-15 10.1002

Iranian Journal of Electrical and Electronic Engineering IJEEE 1735-2827 1735-2827 2011 7 3 S. Shaerbaf shaerbaf@gmail.com S. A. R. Seyedin seyedin@um.ac.ir Chaos based communications have drawn increasing attention over the past years. Chaotic signals are derived from non-linear dynamic systems. They are aperiodic, broadband and deterministic signals that appear random in the time domain. Because of these properties, chaotic signals have been proposed to generate spreading sequences for wide-band secure communication recently. Like conventional DS-CDMA systems, chaos-based CDMA systems suffer from multi-user interference (MUI) due to other users transmitting in the cell. In this paper, we propose a novel method based on radial basis function (RBF) for both blind and non-blind multiuser detection in chaos-based DS-CDMA systems. We also propose a new method for optimizing generation of binary chaotic sequences using Genetic Algorithm. Simulation results show that our proposed nonlinear receiver with optimized chaotic sequences outperforms in comparison to other conventional detectors such as a single-user detector, decorrelating detector and minimum mean square error detector, particularly for under-loaded CDMA condition, which the number of active users is less than processing gain. Chaos-Based Communication DS-CDMA Radial Basis Function Multi-User Detection 2011 9 01 149 160 http://ijeee.iust.ac.ir/article-1-383-en.pdf

24-341 2026-09-15 10.1002

Iranian Journal of Electrical and Electronic Engineering IJEEE 1735-2827 1735-2827 2011 7 3 F. Mohseni-Kolagar f.mohseni@stu.nit.ac.ir H. Miar-Naimi h_miare@nit.ac.ir Due to the nonlinear nature of the Bang-Bang phase-locked loops (BBPLLs), its transient analysis is very difficult. In this paper, new equations are proposed for expression of transient behavior of the second order BBPLLs to phase step input. This approach gives new insights into the transient behavior of BBPLLs. Approximating transient response to reasonable specific waveform the loop transient time characteristics such as locking time, peak time, rise time and over shoot are derived with acceptable accuracy. The validity of the resulted equations is verified through simulations using MATLAB SIMULINK. Simulation results show the high accuracy of the proposed method to model BBPLLs behavior. Bang-Bang PLL Nonlinear Operation Transient Analysis CDR Circuits Alexander PD 2011 9 01 161 167 http://ijeee.iust.ac.ir/article-1-341-en.pdf

24-346 2026-09-15 10.1002

Iranian Journal of Electrical and Electronic Engineering IJEEE 1735-2827 1735-2827 2011 7 3 Sh. Kasaei skasaei@sharif.edu E. Shabani Nia shabaninia@ce.sharif.edu Multicamera vehicle tracking is a necessary part of any video-based intelligent transportation system for extracting different traffic parameters such as link travel times and origin/destination counts. In many applications, it is needed to locate traffic cameras disjoint from each other to cover a wide area. This paper presents a method for tracking moving vehicles in such camera networks. The proposed method introduces a new method for handling inter-object occlusions as the most challenging part of the single camera tracking phase. This approach is based on coding the silhouette of moving objects before and after occlusion and separating occluded vehicles by computing the longest common substring of the related chain codes. In addition, to improve the accuracy of the tracking method in the multicamera phase, a new feature based on the relationships among surrounding vehicles is formulated. The proposed feature can efficiently improve the efficiency of the appearance (or space-time) features when they cannot discriminate between correspondent and non-correspondent vehicles due to noise or dynamic condition of traffic scenes. A graph-based approach is then used to track vehicles in the camera network. Experimental results show the efficiency of the proposed methods. Disjoint-Views Multicameras Occlusion Tracking Neighbors’ Relationships 2011 9 01 168 178 http://ijeee.iust.ac.ir/article-1-346-en.pdf

24-382 2026-09-15 10.1002

Iranian Journal of Electrical and Electronic Engineering IJEEE 1735-2827 1735-2827 2011 7 3 A. Acharyya aribesu.acharyya@gmail.com J. P. Banerjee aribesu.acharyya@gmail.com The effect of optical illumination on DC and dynamic performance of Si1-xGex based double drift region (DDR) (p+pnn+) IMPATT diode operating at W-Band is investigated and compared with its Silicon counterpart. Top Mounted (TM) and Flip Chip (FC) structures are chosen and the composition of photocurrent is altered by shining light on the p+ side and n+ side of the device through optical windows. A double iterative computer simulation method based on drift-diffusion model has been used to study the small signal performance and subsequent modification of the small signal parameters owing to optical illumination. The role of leakage current in controlling the dynamic properties is studied by varying the current multiplication factors for electrons (Mn) and for holes (Mp). It is observed that both the DC and small signal parameters of both the diodes are affected significantly due to optical illumination. Under optical illumination of the device, the frequency shift is observed to be more upwards upon lowering of Mn than lowering of Mp for both the diodes. The frequency chirping in both Si1-xGex and Si IMPATTs are found to be of the order of few GHz, thereby indicating their high photo-sensitiveness at W-Band. But the results significantly indicates that photo-sensitiveness of Si1-xGex IMPATT is much greater than the Si IMPATT which is one of the major findings of this work. Millimeter Wave Frequency Optical Illumination Silicon Germanium Flip Chip Structure Top Mounted Structure Double Drift IMPATT Diode 2011 9 01 179 189 http://ijeee.iust.ac.ir/article-1-382-en.pdf

24-334 2026-09-15 10.1002

Iranian Journal of Electrical and Electronic Engineering IJEEE 1735-2827 1735-2827 2011 7 3 A. Tavakoli tavakoly.ahmad@gmail.com A. Gholami gholami@iust.ac.ir Gas-insulated substations (GIS) have different specifications in proportion to air-insulated substations. Transformer failures related to lightning and switching are often reported in the gas insulated substation (GIS). This problem is the voltage magnifications due to reflections of switching and lightning surges at various junctions within the GIS. thereby overvoltages in GIS are more important than air-insulated substation. There are methods to suppress the stresses created by lightning and switching. However, these methods are suitable before installing the substation and during the substation design period. This paper presents feasible methods for mitigation of the overvoltage magnitude. The advantages of the proposed methods are their simplicity and low cost for implantation along with producing minimal changes in the installed GIS. Gas-Insulated Substations (GIS) Transient Overvoltages Switching Operations Lightning Very Fast Transient Overvoltages (VFTOs) Very Fast Transient Currents (VFTCs) Suppression 2011 9 01 190 196 http://ijeee.iust.ac.ir/article-1-334-en.pdf

24-342 2026-09-15 10.1002

Iranian Journal of Electrical and Electronic Engineering IJEEE 1735-2827 1735-2827 2011 7 3 M. Jamali m.jamali@stu.nit.ac.ir M. Mirzaie mirzaie@nit.ac.ir S. A. Gholamian gholamian@nit.ac.ir The phenomenon of magnetizing inrush is a transient condition, which occurs primarily when a transformer is energized. The magnitude of inrush current may be as high as ten times or more times of transformer rated current that causes malfunction of protection system. So, for safe running of a transformer, it is necessary to distinguish inrush current from fault currents. In this paper, an equivalent instantaneous inductance (EII) technique is used to discriminate inrush current from fault currents. For this purpose, a three-phase power transformer has been simulated in Maxwell software that is based on finite elements. This three-phase power transformer has been used to simulate different conditions. Then, the results have been used as inputs in MATLAB program to implement the equivalent instantaneous inductance technique. The results show that in the case of inrush current, the equivalent instantaneous inductance has a drastic variation, while it is almost constant in the cases of fault conditions. Equivalent Instantaneous Inductance Finite Element Inrush Current 2011 9 01 197 202 http://ijeee.iust.ac.ir/article-1-342-en.pdf

24-367 2026-09-15 10.1002

Iranian Journal of Electrical and Electronic Engineering IJEEE 1735-2827 1735-2827 2011 7 3 Sh. Yousefi sh.yousefi@modares.ac.ir M. Parsa Moghaddam parsa@modares.ac.ir V. Johari Majd sh.yousefi@modares.ac.ir In this paper, an agent-based structure of the electricity retail market is presented based on which day-ahead (DA) energy procurement for customers is modeled. Here, we focus on operation of only one Retail Energy Provider (REP) agent who purchases energy from DA pool-based wholesale market and offers DA real time tariffs to a group of its customers. As a model of customer response to the offered real time prices, an hourly acceptance function is proposed in order to represent the hourly changes in the customer’s effective demand according to the prices. Here, Q-learning (QL) approach is applied in day-ahead real time pricing for the customers enabling the REP agent to discover which price yields the most benefit through a trial-and-error search. Numerical studies are presented based on New England day-ahead market data which include comparing the results of RTP based on QL approach with that of genetic-based pricing. Day-Ahead Real-Time Pricing Genetic Algorithm Hourly Acceptance Function Multi-Agent Systems Q-Learning 2011 9 01 203 212 http://ijeee.iust.ac.ir/article-1-367-en.pdf