2024-03-29T01:33:50Z
https://eej.aut.ac.ir/?_action=export&rf=summon&issue=38
AUT Journal of Electrical Engineering
2588-2910
2588-2910
2009
41
2
Active Filter Control Method Based on Direct Power Control for Compensating Reactive Powers due to Unbalanced Voltages and Nonlinear Loads
E.
Abirii
M.R.
Salehiii
A.
Abrishamifariii
Active filters have proven to be more effective than passive techniques to improve power quality and to solve harmonic and power factor problems due to nonlinear loads. This paper proposes a control scheme based on the instantaneous active and reactive power. The inverter of this active filter is a three-phase, two-level converter. Space vector technique is used as modulators and pattern generators for the Pulse Width Modulated converter. Virtual Flux and a Phase Locked Loop based on a Double Synchronous Reference Frame cause this control system be resistant to the majority of line voltage disturbances. Good dynamic response, independent control of active and reactive powers and also unity power factor of converter are advantages of the proposed method. The operation of the proposed control strategy is verified in MATLAB simulation environment
active filter
DPC
Power Quality
harmonics
2009
11
01
1
8
https://eej.aut.ac.ir/article_279_4556dad4d653094fa8ba472bdf8a2dc2.pdf
AUT Journal of Electrical Engineering
2588-2910
2588-2910
2009
41
2
ISAR Image Improvement Using STFT Kernel Width Optimization Based On Minimum Entropy Criterion
M.
Modarres-Hashemi
M.
Dorostgan
M. M.
Naghshiii *
Nowadays, Radar systems have many applications and radar imaging is one of the most important of these applications. Inverse Synthetic Aperture Radar (ISAR) is used to form an image from moving targets. Conventional methods use Fourier transform to retrieve Doppler information. However, because of maneuvering of the target, the Doppler spectrum becomes time-varying and the image is blurred. Joint Time-Frequency Transforms (JTFT) like Short-Time Fourier Transform (STFT) can resolve the Doppler spectrum and reduce the image blurring. These transforms use some kernels for signal spectrum analysis. According to the uncertainty principle, the proper selection of this kernel and its parameters could affect the quality of the image. In this paper, using a conventional kernel for STFT, i.e. Gaussian kernel, we use minimum entropy criterion to optimize the kernel duration. Simulation results show that this optimization can improve the constructed image compared with the Fourier transform method.
Imaging Radar
ISAR
Joint Time-Frequency Transform
Entropy
Normalized correlation
2009
11
01
9
16
https://eej.aut.ac.ir/article_280_d70481b09bf6bd2de0e7ced2b47b239a.pdf
AUT Journal of Electrical Engineering
2588-2910
2588-2910
2009
41
2
A Solution to View Management to Build a Data Warehouse
N.
Daneshpour
A.
Abdollahzadeh Barfourosh
Several techniques exist to select and materialize a proper set of data in a suitable structure that manage the queries submitted to the online analytical processing systems. These techniques are called view management techniques, which consist of three research areas: 1) view selection to materialize, 2) query processing and rewriting using the materialized views, and 3) maintaining materialized views. There are several parameters should be considered in order to find the most important algorithm for view management. As various researches have been done to propose view selection algorithms, we should select and modify the most suitable algorithm for view materialization based on the properties of the applications. In this paper, we investigate and find relevant parameters to view selection algorithms and classify them based on these parameters. We also present a system to evaluate algorithms and compare them with respect to the values of the evaluation parameters. Based on the results of these activities, we propose a roadmap that helps us choose the most efficient view selection algorithm concerning application types.
Algorithm classification
data warehousing
view management
view materialization
view selection
2009
11
01
17
27
https://eej.aut.ac.ir/article_281_921feaff71a8f4754313270d116e8bbf.pdf
AUT Journal of Electrical Engineering
2588-2910
2588-2910
2009
41
2
A Quantitative Evaluation of Maintainability of Software Architecture Styles
G.R.
Shahmohammadii
S.
Jalili
Proper decisions play a crucial role in any software architecture design process. An important decision of design stage is the selection of a suitable software architecture style. Lack of investigation on the quantitative impact of architecture styles on software quality attributes is the main problem in using such styles. Consequently, the use of architecture styles in designing is based on the intuition of software developers. The aim of this research is to quantify the impacts of architecture styles on software maintainability that is an expected quality of each software. In this study, architecture styles are quantified based on coupling, complexity and cohesion metrics and ranked by analytic hierarchy process from a maintainability viewpoint. Metrics validation confirms fitness of the metrics. Regarding the great impact of this decision on maintainability of software product, the presented parametric model provides a basis for sensible selection of architecture style.
Software Architecture
Architectural Style
Coupling
Complexity
Cohesion
Maintainability Evaluation
2009
11
01
29
38
https://eej.aut.ac.ir/article_282_9deda979381c5e1442657f54acd72c5b.pdf
AUT Journal of Electrical Engineering
2588-2910
2588-2910
2009
41
2
Voltage Coordination of FACTS Devices in Power Systems Using RL-Based Multi-Agent Systems
M. R.
Tousii
S. H.
Hosseinianii
Mohammad B
Menhaji
This paper describes how multi-agent system technology can be used as the underpinning platform for voltage control in power systems. In this study, some FACTS (flexible AC transmission systems) devices are properly designed to coordinate their decisions and actions in order to provide a coordinated secondary voltage control mechanism based on multi-agent theory. Each device here is modeled as an agent being able to cooperate and communicate with other devices. In this system, individual autonomous agents and intelligent decision makers learn to perform optimal actions through proper interactions with their environments. The SARSA Q-learning, which is an on-policy algorithm in reinforcement learning (RL) is then used and tested successfully in voltage control problem. In this research, the Java Agent DEvelopment (JADE) platform is used to implement the agents and to simulate their communications. The power system is also fully implemented in Java. The proposed intelligent MA based method is finally applied to IEEE 39-buses New England power system. The results of simulation better highlight the merit of the method and its ability in coordinating FACTS devices for removing voltage disturbances.
Multi-Agent Systems (MAS)
Secondary Voltage Control
Voltage Coordination
Reinforcement Learning
Java Agent Development (JADE) Framework
2009
11
01
39
49
https://eej.aut.ac.ir/article_283_0ffd8c085e6339091e867e2b075f7662.pdf
AUT Journal of Electrical Engineering
2588-2910
2588-2910
2009
41
2
A Modified Hybrid MoM-Modal Method for Shielding Effectiveness Evaluation of Rectangular Enclosures with Multiple Apertures
V.
Rezaeii
R.
Moinii
S. H. H.
Sadeghii
F
.Rachdiii
A new hybrid modal-moment method is proposed to calculate fields penetrated through small apertures on rectangular metallic enclosures. First, the method of moments is used to numerically solve the governing electric field integral equation for the equivalent two-dimensional surface-current distributions on the surface of metallic enclosure including any number of rectangular apertures of arbitrary lay-out. The resultant exterior scattered fields are then used as the input to a testing procedure to obtain aperture field distributions in the modal expansion technique. These fields can be directly transferred to interior penetrated fields, using appropriate Green’s function of the cavity inside region. To validate the method proposed in this paper, the results of the proposed method are compared with the measurement results available in the literature and those obtained using the conventional modal-moment method for both single and double aperture enclosures. It is shown that the proposed method offers a remarkable improvement in computation burden over the conventional method, especially for calculation of field penetration through much number of apertures typical to realistic measures in the discipline of electromagnetic compatibility.
Shielding Effectiveness
Hybrid methods
Electric field integral equation
Rectangular enclosures
Rectangular apertures
2009
11
01
51
58
https://eej.aut.ac.ir/article_284_3ea4f1cc22f2ecf1a810fb8fceca3b2a.pdf
AUT Journal of Electrical Engineering
2588-2910
2588-2910
2009
41
2
Modeling of Tactile Detection of an Artery in a Soft Tissue by Finite Element Analysis
Ali
Abouei Mehrizi
Siamak
Najarian
Majid
Moiniiii
Nowadays, one of the main problems encountered in minimally invasive surgery and telesurgery is the detection of arteries in tissue. In this study, for the first time, tactile detection of an artery in tissue and distinguishing it from the tumor has been modeled by finite element method. In this modeling, three 2D models of tissue have been created: tissue, tissue including a tumor, and tissue including an artery. After solving three models with similar boundary conditions and loadings, first, the 2D tactile mappings and stress graphs for upper nodes of models, which have the role of transferring tactile data, have been explored. Comparing these results, if stress values of nodes are equal and constant, tissue is without tumor or artery. In addition, it was concluded that if stress graph includes a peak, the tissue has a tumor or an artery and that the stress graph of tissue including artery is time-dependent in comparison with the tissue including the tumor.
Soft tissue
tumor
artery
tactile detection
Finite Element Method (FEM)
2009
11
01
59
63
https://eej.aut.ac.ir/article_285_74df718ecedc3c8144e1c1c53f9b35ba.pdf
AUT Journal of Electrical Engineering
2588-2910
2588-2910
2009
41
2
Design of a Fuzzy Controller Chip with New Structure, Supporting Rational-Powered Membership Functions
A.
Naderii
H.
Ghasemzadehii
A.
Pourazar
M.
Aliasgharyii
In this paper, a new structure possessing the advantages of low-power consumption, less hardware and high-speed is proposed for fuzzy controller. The maximum output delay for general fuzzy logic controllers (FLC) is about 86 ns corresponding to 11.63 MFLIPS (fuzzy logic inference per second) while this amount of the delay in the designed fuzzy controller becomes 52ns that corresponds to 19.23 MFLIPS. This mixed analog/digital realization of the circuit makes the design programmable and extendable. The proposed controller supports Rational-Power Membership Functions with a resolution of 0.03125. Simulation results of the controller using HSPICE simulator level 49 in 0.35um in CMOS process technology (BSIM3v3) show an average power consumption of 4.38mW, and an RMS error of 1.26%. This controller can be used in many applications in which there is a need for a controller chip by correct programming with system experts. Meanwhile the whole area of the chip is 0.0775mm2.
Fuzzy controller
Rational-powered membership function
CMOS
low power
2009
11
01
65
71
https://eej.aut.ac.ir/article_286_5c15364c5b353bf0683b2c3e5d5ce69b.pdf