@article { author = {J. Faiz, J. and Takbash, A. M. and Mazaheri-Tehrani, E.}, title = {Application of Signal Processing Tools for Fault Diagnosis in Induction Motors-A Review-Part II}, journal = {AUT Journal of Electrical Engineering}, volume = {50}, number = {1}, pages = {3-12}, year = {2018}, publisher = {Amirkabir University of Technology}, issn = {2588-2910}, eissn = {2588-2929}, doi = {10.22060/eej.2017.13220.5143}, abstract = {The use of efficient signal processing tools (SPTs) to extract proper indices for the fault detection in induction motors (IMs) is the essential part of any fault recognition procedure. The 2nd part of this two-part paper is, in turn, divided into two parts. Part two covers the signal processing techniques which can be applied to non-stationary conditions. In this paper, all utilized SPTs for non-stationary conditions have been employed in details for fault detection in IMs. Then, their competency and their drawbacks to extract indices in the transient state modes are investigated from different aspects. The considerable experimental results are given to certify the present discussion. Different kinds of faults including eccentricity, broken bar, and bearing faults as major internal faults in IMs are investigated.}, keywords = {Cuckoo Optimization Algorithm,Greedy Geographic Forwarding based,on Geospatial Division Algorithm,Energy Efciency,Underwater Wireless Sensor Networks}, url = {https://eej.aut.ac.ir/article_1971.html}, eprint = {https://eej.aut.ac.ir/article_1971_44c23a9bc2ce28d08c1574c28ea8bf68.pdf} } @article { author = {Rasti, M. and Kazemi Taskou, Sh.}, title = {On Joint Sub-channel Allocation, Duplexing Mode Selection, and Power Control in Full-Duplex Co-Channel Femtocell Networks}, journal = {AUT Journal of Electrical Engineering}, volume = {50}, number = {1}, pages = {13-24}, year = {2018}, publisher = {Amirkabir University of Technology}, issn = {2588-2910}, eissn = {2588-2929}, doi = {10.22060/eej.2017.12662.5103}, abstract = {As one of the promising approaches to increase the network capacity, Full-duplex (FD) communications have recently gained a remarkable attention. FD communication enables wireless nodes to simultaneously send and receive data through the same frequency band. Thanks to the recent achievements in the self-interference (SI) cancellation, this type of communication is expected to be potentially utilized in cellular systems, especially in small cell networks. In this paper, we integrate the FD communications into femtocell networks where femtocell users (FUs) share the same spectrum with macro users (MUs). In particular, aiming to maximize the number of admitted FUs in the network and satisfying the target rate for FUs, we jointly study the problem of sub-channel allocation, duplexing-mode selection, and power control for FUs in both uplink (UL) and downlink (DL) transmissions. Moreover, we address the power control problem for macro-tier where the main goal is to minimize the transmission power of prioritized MUs while guaranteeing a target rate for them. To jointly address these problems for both tiers, we propose a distributed algorithm in which FBSs and admitted FUs choose whether to operate in half-duplex (HD) or FD mode so as to meet their target rate. The convergence and performance of the proposed algorithm are evaluated through simulation where it is demonstrated that the average admission ratio of FUs in our proposed distributed scheme surpasses the existing traditional HD approaches.}, keywords = {Duplexing mode,Full-duplex communication,Half-duplex,OFDMA,Sub-channel allocation,Two-tier networks}, url = {https://eej.aut.ac.ir/article_1968.html}, eprint = {https://eej.aut.ac.ir/article_1968_83bbb6cf91e4342d066de92066be5cb8.pdf} } @article { author = {Rahmani, R. and Fakharian, A.}, title = {A Distributed Control Architecture for Autonomous Operation of a Hybrid AC/DC Microgrid System}, journal = {AUT Journal of Electrical Engineering}, volume = {50}, number = {1}, pages = {25-32}, year = {2018}, publisher = {Amirkabir University of Technology}, issn = {2588-2910}, eissn = {2588-2929}, doi = {10.22060/eej.2017.12312.5062}, abstract = {Hybrid AC/DC microgrids facilitate the procedure of DC power connection into the conventional AC power system by developing the distributed generations (DGs) technologies. The conversion processes between AC and DC electrical powers are more convenient by hybrid systems. In this paper, an energy management system (EMS) for a hybrid microgrid network is proposed due to the optimal utilization of renewable energy resources. EMS is designed based on two separate control parts, including proportional resonance (PR) and proportional integral (PI) controllers for managing the performance of two distribution generator (DG) and photo-voltaic (PV) sources. The novelty of implemented control scheme is the accurate prediction and recognition of load demand range with considering the DC bus voltage for coordinating the local sources. The advantage of this method is the proper control of both stable and transient states in power-sharing moments. The simulation results verify that the system outputs satisfy the load and power network requirements.}, keywords = {Hybrid microgrid management system (HMMS),PI controller,PR controller,PV unit,stability}, url = {https://eej.aut.ac.ir/article_1961.html}, eprint = {https://eej.aut.ac.ir/article_1961_0f669b37186d4a9f08d38d5b3bf4fe36.pdf} } @article { author = {Abedi, M. and Emadi, M. J}, title = {Optimal Power Management to Minimize SER in Amplify and-Forward Relay Networks}, journal = {AUT Journal of Electrical Engineering}, volume = {50}, number = {1}, pages = {33-42}, year = {2018}, publisher = {Amirkabir University of Technology}, issn = {2588-2910}, eissn = {2588-2929}, doi = {10.22060/eej.2017.13060.5131}, abstract = {This paper studies optimal power allocation to minimize symbol error rate (SER) of amplify-and-forward cooperative diversity networks. First, we analytically solve optimal power allocation problem to minimize SER for three different scenarios, namely, multi-branch single-relay, single-branch multi-relay and multi-branch multi-relay cooperative diversity networks, all subject to a given total relay power consumption. In addition to the total relay power constraint, for the multi-branch single-relay scenario. Next, we assume that every single relay is subject to a maximum power constraint. To this end, we present an iterative algorithm to find the optimal power rates. Finally, we study an off-line scenario in which the relays are energy harvester and equipped with infinite-sized batteries. For this scenario, the maximum SER is minimized over the whole harvesting time slots. We propose a water filling algorithm for the classical relay channel and an iterative algorithm for the multi-branch single-relay cooperative scheme. Through the numerical results, it is shown that optimal power allocation policies enhance the system performance.}, keywords = {Cooperative diversity network,Optimal power allocation,Symbol error rate,Water filling algorithm,Battery}, url = {https://eej.aut.ac.ir/article_1983.html}, eprint = {https://eej.aut.ac.ir/article_1983_e77023186bc81d9a069d48f6d5e36c6c.pdf} } @article { author = {Sharifi, A.A and Mofarreh-Bonab, M.}, title = {Spectrum Sensing Data Falsification Attack in Cognitive Radio Networks: An Analytical Model for Evaluation and Mitigation of Performance Degradation}, journal = {AUT Journal of Electrical Engineering}, volume = {50}, number = {1}, pages = {43-50}, year = {2018}, publisher = {Amirkabir University of Technology}, issn = {2588-2910}, eissn = {2588-2929}, doi = {10.22060/eej.2017.12528.5094}, abstract = {Cognitive Radio (CR) networks enable dynamic spectrum access and can significantly improve spectral efficiency. Cooperative Spectrum Sensing (CSS) exploits the spatial diversity between CR users to increase sensing accuracy. However, in a realistic scenario, the trustworthy of CSS is vulnerable to Spectrum Sensing Data Falsification (SSDF) attack. In an SSDF attack, some malicious CR users deliberately report falsified local sensing results to a data collector or Fusion Center (FC) and, then, affect the global sensing decision. In the present study, we investigate an analytical model for a hard SSDF attack and propose a robust defense strategy against such an attack. We show that FC can apply learning and estimation methods to obtain the attack parameters and use a better defense strategy. We further assume a log-normal shadow fading wireless environment and discuss the attack parameters that can affect the strength of SSDF attack. Simulation results illustrate the effectiveness of the proposed defense method against SSDF attacks, especially when the malicious users are in the majority.}, keywords = {Cognitive Radio,Cooperative Spectrum Sensing,Spectrum Sensing Data Falsification Attack,Malicious User}, url = {https://eej.aut.ac.ir/article_1979.html}, eprint = {https://eej.aut.ac.ir/article_1979_cbdb531b13a25ba73caacb6553483adf.pdf} } @article { author = {Menhaj, M. B and Dehghani1, M. A. and Azimi, M.}, title = {Airborne Seeker Application in Three Dimensional Formation Flight of UAVs}, journal = {AUT Journal of Electrical Engineering}, volume = {50}, number = {1}, pages = {51-59}, year = {2018}, publisher = {Amirkabir University of Technology}, issn = {2588-2910}, eissn = {2588-2929}, doi = {10.22060/eej.2017.12493.5083}, abstract = {This paper deals with the leader-follower formation control problem while communication constraint in data transmitting is considered. From a practical point of view, we study the case in which unmanned vehicles are subject to the limited sensing, and communication is of a particular interest. A three-dimensional formation flight of multi-unmanned aerial vehicles with leader-follower configuration is investigated. We assume that the follower is equipped with an airborne seeker to measure the relative kinematic parameters with respect to the leader. Considering practical measurements of the airborne seeker, the kinematics of the leader-follower system is derived and by employing a cascade loop controller, the relative angle and the relative range are regulated to reach at the desired formation. Moreover, by modeling the seeker mechanism, the effect of the seeker dynamics and sensor measurement noise on the performance of the proposed formation control scheme are studied. Simulation results verify the effectiveness of the proposed leader-follower formation control structure}, keywords = {Airborne seeker,Formation flight problem,Leader-Follower configuration,Unmanned Aerial Vehicles}, url = {https://eej.aut.ac.ir/article_1990.html}, eprint = {https://eej.aut.ac.ir/article_1990_d3bfb97cfe645cb5c00e0a4b06a688b1.pdf} } @article { author = {Yeganeh, H. and Salahi, A. and Pourmina, M. A}, title = {Reduction of Energy Consumption in Mobile Cloud Computing by ‎Classification of Demands and Executing in Different Data Centers}, journal = {AUT Journal of Electrical Engineering}, volume = {50}, number = {1}, pages = {59-66}, year = {2018}, publisher = {Amirkabir University of Technology}, issn = {2588-2910}, eissn = {2588-2929}, doi = {10.22060/eej.2017.13284.5150}, abstract = { In recent years, mobile networks have faced with the increase of traffic demand. By emerging mobile applications and cloud computing, Mobile Cloud Computing (MCC) has been introduced. In this research, we focus on the 4th and 5th generation of mobile networks. Data Centers (DCs) are connected to each other by high-speed links in order to minimize delay and energy consumption. By considering a model of the geographical distribution of DCs which uses a wideband optical network, renewable energy and sharing resources for new generations of mobile networks, the real effect of issues on the consumed energy, cost, and profit in the mobile cloud computing are investigated. We derived a penalty function for cost and then by using Lyapunov optimization theorem; we designed an algorithm to minimize the average cost of energy consumption based on the online information in MCC. The time average cost is at most O(1/V) above the optimum target, while the average queue size is O(V). The parameter V can be tuned to make the time average cost as close to (or below) the optimum as desired. We designed three scenarios and two classes of applications to set up our simulation environment. The provided results illustrate the efficiency of our proposed scheme and validate the mathematical model.}, keywords = {Mobile Cloud Computing,Lyapunov Optimization,energy consumption,Penalty Function,Demand Classification}, url = {https://eej.aut.ac.ir/article_2689.html}, eprint = {https://eej.aut.ac.ir/article_2689_bcea59731617cf25db36cac92a72e6cc.pdf} } @article { author = {Zaheri Abdevand, R. and khoshsaadat, A. and Shokrollah Moghani, J. and Abedi, M.}, title = {Fast Transient Hybrid Neuro Fuzzy Controller for STATCOM During Unbalanced Voltage Sags}, journal = {AUT Journal of Electrical Engineering}, volume = {50}, number = {1}, pages = {67-74}, year = {2018}, publisher = {Amirkabir University of Technology}, issn = {2588-2910}, eissn = {2588-2929}, doi = {10.22060/eej.2017.12153.5048}, abstract = {A static synchronous compensator (STATCOM) is generally used to regulate voltage and improve transient stability in transmission and distribution networks. This is achieved by controlling reactive power exchange between STATCOM and the grid. Unbalanced sags are the most common type of voltage sags in distribution networks. A static synchronous compensator (STATCOM) is generally used to maintain voltage and improve transient stability. This is achieved by regulating reactive power exchange between compensator device and grid. In this paper, A hybrid neuro-fuzzy current controller for STATCOM control is proposed. The controller has minimum mass of calculations. Learning process is carried out by an improved supervisory error-back propagation (SEBP) method instead of usual EBP algorithm. This results in better performance and efficiency and leads to a robust model with fast transient capability. The model is developed in MATLAB/SIMULINK environment. STATCOM operation during scenarios of balanced and unbalanced voltage sags is studied. Performance is compared with the operation of a conventional proportional-resonant controller. The results show faster dynamic and better capability of neuro-fuzzy controller in responding to voltage sag occurrences.}, keywords = {Static synchronous compensator,Voltage sag,Neuro-fuzzy systems}, url = {https://eej.aut.ac.ir/article_2662.html}, eprint = {https://eej.aut.ac.ir/article_2662_d488294221a399ed6a5da987dac7d5ce.pdf} } @article { author = {Babaei, E. and Feyzi, H. and Gholizadeh-Roshanagh, R.}, title = {A New Topology of Embedded Z-H Buck-Boost Converter}, journal = {AUT Journal of Electrical Engineering}, volume = {50}, number = {1}, pages = {75-84}, year = {2018}, publisher = {Amirkabir University of Technology}, issn = {2588-2910}, eissn = {2588-2929}, doi = {10.22060/eej.2017.12141.5045}, abstract = {In this paper, a new embedded Z-H (EZ-H) buck-boost converter is proposed. In this topology, two identical dc voltage sources are embedded in a LC network in a series connection with the inductors. The proposed converter eliminates the shoot-through (ST) switching state and there is no need for a front-end diode. Other advantages of the proposed topology are having capability of buck and boost operations in one structure; reaching the maximum gain in the duty cycle near 0.5; lowering ripples of voltage and current; and particularly reducing the voltage stress on the capacitors. In this paper, the voltage and current equations of all the components are extracted with considering all the operation modes. In addition, a suitable switching method is presented for the proposed converter to generate the desired output voltage. The ripple values of inductors and capacitors are calculated. Simulation results by the PSCAD/EMTDC software show accuracy and performance of the proposed.converter.}, keywords = {Embedded structure,Z-Source inverter,Z-H buck-boost converter}, url = {https://eej.aut.ac.ir/article_2710.html}, eprint = {https://eej.aut.ac.ir/article_2710_ca0ce856d20add7be7c6eb704df903ad.pdf} } @article { author = {Mahmoudi, A. and HOSSEINIAN, S. H and Zarabadipour, H.}, title = {A Direct Matrix Inversion-Less Analysis for Distribution System Power Flow Considering Distributed Generation}, journal = {AUT Journal of Electrical Engineering}, volume = {50}, number = {1}, pages = {85-92}, year = {2018}, publisher = {Amirkabir University of Technology}, issn = {2588-2910}, eissn = {2588-2929}, doi = {10.22060/eej.2017.11646.4984}, abstract = {This paper presents a new direct matrix inversion-less analysis for radial distribution systems (RDSs). The method can successfully deal with weakly meshed distribution systems. (WMDSs). Being easy to implement, direct methods (DMs) provide an excellent performance. Matrix inversion is the mean reason of divergence and low-efficiency in power flow algorithms. In this paper, the performance of the proposed DM is upgraded since it is no longer necessary to use the matrix inversion and its related computations. On the other hand, DMs have not been explicitly developed for different models of loads and, moreover, analyzing meshes in previous works decreases the efficiency of such methods. This paper deals with these issues and takes a few steps forward. The modeling of distributed generations in distribution systems is also studied which is an interesting topic nowadays. Simulations results for balanced, unbalanced, meshed and radial systems with distributed generations verify the performance of the proposed method.}, keywords = {Distribution power flow,direct solution,matrix inversion,equivalent load impedance,distributed generation}, url = {https://eej.aut.ac.ir/article_2690.html}, eprint = {https://eej.aut.ac.ir/article_2690_9523f2ad317d403b61ada5667d3b0525.pdf} } @article { author = {Dosaranian-Moghadam, M. and Amo-Rahimi, Z.}, title = {Energy Efficiency and Reliability in Underwater Wireless Sensor Networks Using Cuckoo Optimizer Algorithm}, journal = {AUT Journal of Electrical Engineering}, volume = {50}, number = {1}, pages = {93-100}, year = {2018}, publisher = {Amirkabir University of Technology}, issn = {2588-2910}, eissn = {2588-2929}, doi = {10.22060/eej.2018.13347.5154}, abstract = {Energy efficiency and reliability are widely understood to be one of the dominant considerations for Underwater Wireless Sensor Networks (UWSNs). In this paper, in order to maintain energy efficiency and reliability in a UWSN, Cuckoo Optimization Algorithm (COA) is adopted that is a combination of three techniques of geo-routing, multi-path routing, and Duty-Cycle mechanism. In the proposed algorithm, by presenting a cost function in COA algorithm, a hop-by-hop method of route selection is performed using power consumption and energy content of the current node; while in Greedy Geographic Forwarding based on Geospatial Division (GGFGD) algorithm, data transfer is based on the closest route to a destination criterion. Simulation results show that despite the increase in path lengths and the resulting increase in propagation delay, the remaining energy of the UWSN increases using the proposed technique compared to GGFGD algorithm. Besides, we will show that while improving energy consumption, the number of paths found and, therefore, reliability of the network in the proposed method that uses duty-cycle mechanism are higher than the ones in GGFGD algorithm.}, keywords = {Cuckoo Optimization Algorithm,Greedy Geographic Forwarding based on Geospatial Division Algorithm,Energy Efficiency,Underwater Wireless Sensor Networks}, url = {https://eej.aut.ac.ir/article_2779.html}, eprint = {https://eej.aut.ac.ir/article_2779_0149ae8827b0dc27d44c97c4dd41dbd5.pdf} } @article { author = {Haddadi, A. and Ghorbani, A.}, title = {Distorted Reflector Antennas: Radiation Pattern Sensitivity to the Surface Distortions}, journal = {AUT Journal of Electrical Engineering}, volume = {50}, number = {1}, pages = {101-106}, year = {2018}, publisher = {Amirkabir University of Technology}, issn = {2588-2910}, eissn = {2588-2929}, doi = {10.22060/eej.2017.11922.5016}, abstract = {The high-frequency performance of the reflector antennas is mainly limited by the surface. It has been shown that distortions on different regions of the reflector surface can have different effects on the radiation performance. In other words, degradation of the radiation pattern due to the presence of surface distortions is sensitive to the location and behavior of the surface distortion profile. In this paper, the concept of “sensitivity of the radiation pattern to the surface distortion” has been introduced and quantified. It can be used in the design of different reflector antennas to prevent radiation degradations due to surface distortion. Based on the Physical Optics and variational analysis, the first-order variational of the far-fields with respect to the surface profile is formulated to present the concept of sensitivity. The variational amplitude can be modified to show the concept of sensitivity of the radiation pattern to the distortions on the surface. Reflector antennas with different geometries and feeding methods have different sensitivity plots. Both co- and cross-polarization fields for feed antenna are considered ti be used in the symmetric and offset reflectors, and sensitivity plots are extracted. Sensitivity plots show areas on the surface that have stronger effects on the radiation pattern variations in the region of the main-lobe and the first few side-lobes.}, keywords = {Reflector antenna,surface distortion,offset reflector antenna}, url = {https://eej.aut.ac.ir/article_2781.html}, eprint = {https://eej.aut.ac.ir/article_2781_9055d48bbae3c0773cd4edcc79359d76.pdf} }