Showing 102 results for Ica
S. Khosroazad, N. Neda, H. Farrokhi,
Volume 12, Issue 3 (9-2016)
Abstract
Physical-layer network coding (PLNC) has the ability to drastically improve the throughput of multi-source wireless communication systems. In this paper, we focus on the problem of channel tracking in a Decode-and-Forward (DF) OFDM PLNC system. We proposed a Kalman Filter-based algorithm for tracking the frequency/time fading channel in this system. Tracking of the channel is performed in the time domain while data detection is implemented in the frequency domain. As an important advantage, this approach does not need for training of some subcarriers in every OFDM symbols and this, results in higher throughput, compared to other methods. High accuracy, no phase ambiguity, and stability in fast fading conditions are some other advantages of this approach.
A. Ejlali, J. Soleimani, A. Vahedi,
Volume 12, Issue 4 (12-2016)
Abstract
Recently, Transverse Flux Permanent Magnet Generators (TFPMGs) have been proposed as a possible generator in direct drive variable speed wind turbines due to their unique merits. Generally, the quality of output power in these systems is lower than multi stage fixed speed systems, because of removing the gears, so it’s important to design these kinds of generators with low ripple and lowest harmful harmonics and cogging torque that is one of the most important terms in increasing the quality of output power of generator. The objective of this paper is introducing a simple design method and optimization of high power TFPMG applied in vertical axis direct drive wind turbine system by lowest possible amplitude of cogging torque and highest possible power factor, efficiency and power density. In order to extract the output values of generator and sensitivity analysis for design and optimization, 3D-Finite element model, has been used. This method has high accuracy and gives us a better insight of generator performance and presents back EMF, cogging torque, flux density and FFT of this TFPMG. This study can help designers in design approach of such motors.
M. Khalilzadeh, A. Fereidunian,
Volume 12, Issue 4 (12-2016)
Abstract
In this paper, a stochastic approach is proposed for reliability assessment of bidirectional DC-DC converters, including the fault-tolerant ones. This type of converters can be used in a smart DC grid, feeding DC loads such as home appliances and plug-in hybrid electric vehicles (PHEVs). The reliability of bidirectional DC-DC converters is of such an importance, due to the key role of the expected increasingly utilization of DC grids in modern Smart Grid. Markov processes are suggested for reliability modeling and consequently calculating the expected effective lifetime of bidirectional converters. A three-leg bidirectional interleaved converter using data of Toyota Prius 2012 hybrid electric vehicle is used as a case study. Besides, the influence of environment and ambient temperature on converter lifetime is studied. The impact of modeling the reliability of the converter and adding reliability constraints on the technical design procedure of the converter is also investigated. In order to investigate the effect of leg increase on the lifetime of the converter, single leg to five-leg interleave DC-DC converters are studied considering economical aspect and the results are extrapolated for six and seven-leg converters. The proposed method could be generalized so that the number of legs and input and output capacitors could be an arbitrary number.
M. Khoddam, J. Sadeh, P. Pourmohamadiyan,
Volume 13, Issue 1 (3-2017)
Abstract
Circuit Breakers (CBs) are critical components in power system for reliability and protection. To assure their accurate performance, a comprehensive condition assessment is of an imminent importance. Based on dynamic resistance measurement (DRM), this paper discusses a simple yet effective fuzzy approach for evaluating CB’s electrical contacts condition. According to 300 test results obtained from healthy and three defected electrical contacts, the authors describe the special effect of common failures on DRM characteristics and propose seven deterioration indicators. Using these parameters, a fuzzy classifier is suggested to accurately determine contact sets condition. The salient advantage of the proposed model is its capability to recognize the type of contact failure. The feasibility and effectiveness of the proposed scheme has been validated through 40 real life recorded data of some electrical contacts.
Y. A. Baadj, F. Rogti,
Volume 13, Issue 2 (6-2017)
Abstract
Multidielectric polyethylene is a material that is generally employed as insulation for the HVDC isolations. In this paper, the influence of temperature on space charge dynamics has been studied, low-density polyethylene (LDPE) and Fluorinated Ethylene Propylene (FEP) sandwiched between two electrodes were subjected to voltage application of 5kV (14.3 kV/mm) for extended duration of time and the space charge measurements were taken using bipolar model is one-dimensional, taking into account trapping, detrapping and the rencommbinaison in order to determine the charge density and electric field of the sample depending on the thickness. The simulation was carried out at three different temperatures (20, 40, and 60°C). The results of this model going to compare with experimental space charge measurements . Finally, simulation results demonstrated that the temperature has many effects on the dynamic space charge and of influences the charge injection, charge mobility, electrical conduction, trapping and detrapping.
F. Misaghi, T. Barforoushi, M. Jafari-Nokandi,
Volume 13, Issue 2 (6-2017)
Abstract
In this paper, a novel framework is proposed to study impacts of regulatory incentive on distributed generation (DG) investment in sub-transmission substations, as well as upgrading of upstream transmission substations. Both conventional and wind power technologies are considered here. Investment incentives are fuel cost, firm contracts, capacity payment and investment subsidy relating to wind power. The problem is modelled as a bi-level stochastic optimization problem, where the upper level consists of investor's decisions maximizing its own profit. Both market clearing and decision on upgrading of transmission substation aiming at minimizing the total cost are considered in the lower level. Due to non-convexity of the lower level and impossibility of converting to single level problem (i.e. mathematical programming with equilibrium constraints (MPEC)), an algorithm combing enumeration and mathematical optimization is used to tackle with the non-convexity. For each upgrading strategy of substations, a stochastic MPEC, converted to a mixed integer linear programming (MILP) is solved. The proposed model is examined on a six-bus and an actual network. Numerical studies confirm that the proposed model can be used for analysing investment behaviour of DGs and substation expansion.
M. Sedighizadeh, M. Esmaili, M. M. Mahmoodi,
Volume 13, Issue 3 (9-2017)
Abstract
Distribution systems can be operated in multiple configurations since they are possible combinations of radial and loop feeders. Each configuration leads to its own power losses and reliability level of supplying electric energy to customers. In order to obtain the optimal configuration of power networks, their reconfiguration is formulated as a complex optimization problem with different objective functions and network operating constraints. In this paper, a multi-objective framework is proposed for optimal network reconfiguration with objective functions of minimization of power losses, System Average Interruption Frequency Index (SAIFI), System Average Interruption Duration Index (SAIDI), Average Energy Not Supplied (AENS), and Average Service Unavailability Index (ASUI). The optimization problem is solved by the Imperialist Competitive Algorithm (ICA) as one of the most modern heuristic tools. Since objective functions have different scales, a fuzzy membership is utilized here to transform objective functions into a same scale and then to determine the satisfaction level of the afforded solution using the fuzzy fitness. The efficiency of the proposed method is confirmed by testing it on 32-bus and 69-bus distribution test systems. Simulation results demonstrate that the proposed method not only presents intensified exploration ability but also has a better converge rate compared with previous methods.
N. Okati, M. R. Mosavi, H. Behroozi,
Volume 13, Issue 4 (12-2017)
Abstract
Node cooperation can protect wireless networks from eavesdropping by using the physical characteristics of wireless channels rather than cryptographic methods. Allocating the proper amount of power to cooperative nodes is a challenging task. In this paper, we use three cooperative nodes, one as relay to increase throughput at the destination and two friendly jammers to degrade eavesdropper’s link. For this scenario, the secrecy rate function is a non-linear non-convex problem. So, in this case, exact optimization methods can only achieve suboptimal solution. In this paper, we applied different meta-heuristic optimization techniques, like Genetic Algorithm (GA), Partial Swarm Optimization (PSO), Bee Algorithm (BA), Tabu Search (TS), Simulated Annealing (SA) and Teaching-Learning-Based Optimization (TLBO). They are compared with each other to obtain solution for power allocation in a wiretap wireless network. Although all these techniques find suboptimal solutions, but they appear superlative to exact optimization methods. Finally, we define a Figure of Merit (FOM) as a rule of thumb to determine the best meta-heuristic algorithm. This FOM considers quality of solution, number of required iterations to converge, and CPU time.
A. Jabbari,
Volume 13, Issue 4 (12-2017)
Abstract
A 2D analytical method for magnetic vector potential calculation in inner rotor surface mounted and surface inset permanent magnet machines considering slotting effects, magnetization orientation and winding layout has been proposed in this paper. The analytical method is based on the resolution of Laplace and Poisson equations as well as Maxwell equation in quasi- Cartesian coordinate by using sub-domain method and hyperbolic functions. The developed method is applied on the performance computation of two prototypes surface mounted permanent magnet motors and two prototypes surface inset permanent magnet motors. A radial and a parallel magnetization orientation is considered for each type of motor. The results of these models are validated through FEM method.
S. Arefi Ardakani, A. Badri,
Volume 13, Issue 4 (12-2017)
Abstract
Today due to increasing and evolving of electrical grids, the optimal and profitable energy production is among producers' major concerns. Thus, conventional ways of production and trading energy are being replaced by modern economical procedures. In addition, distributed energy resources (DERs) in form of renewable and conventional resources as well as responsive loads play an important role in this issue. The mutual problem of DERs in joining power market is their rather small production compared to other units and intermittency of the corresponding resources. Forming coalition is an effective way to overcome DER difficulties for participating in power market. In this paper the problem of optimal bidding strategy of DERs integrated as a virtual power plant is investigated. Based on the proposed method, cooperative game is employed to obtain optimal DER outputs and the results are compared with individual non-cooperative bidding model. In order to mitigate the intermittent nature of renewable energies, existence of electric vehicles (EVs) as energy storage facilities in the proposed coalition is investigated. Due to the associated uncertainties regarding EVs and DERs, a stochastic optimization model is used. Finally, Shapley value method is employed to obtain corresponding allocated profits. Results show the eminence of forming coalition in terms of acquiring payoffs and optimal contributions.
S. Kashi, A. Patooghy,
Volume 14, Issue 2 (6-2018)
Abstract
In this paper, we propose a new path-based multicast algorithm that is called Row/Column-First algorithm. The proposed algorithm constructs a set of multicast paths to deliver a multicast message to all multicast destination nodes. The set of multicast paths are all of row-first or column-first subcategories to maximize the multicast performance. The selection of row-first or column-first approaches is done based on the location of multicast source node i.e., how the multicast source is far from right/left and top/bottom margins of the mesh network. In this way, the proposed algorithm improves two performance criteria i.e., traffic and communication latency as compared with the well-known Column-Path multicast algorithm. In order to evaluate the proposed algorithm, an analytical model is developed to estimate the mentioned performance criteria. The modeling and simulation results show improvement of 10 and 20 percent on traffic and communication latency respectively for Row/Column-First algorithm as compared to the Column-Path algorithm.
M. K. Saini, R. K. Beniwal,
Volume 14, Issue 2 (6-2018)
Abstract
This paper presents a new framework based on modified EMD method for detection of single and multiple PQ issues. In modified EMD, DWT precedes traditional EMD process. This scheme makes EMD better by eliminating the mode mixing problem. This is a two step algorithm; in the first step, input PQ signal is decomposed in low and high frequency components using DWT. In the second stage, the low frequency component is further processed with EMD technique to get IMFs. Eight features are extracted from IMFs of low frequency component. Unlike low frequency component, features are directly extracted from the high frequency component. All these features form feature vector which is fed to PNN classifier for classification of PQ issues. For comparative analysis of performance of PNN, results are compared with SVM classifier. Moreover, performance of proposed methodology is also validated with noisy PQ signals. PNN has outperformed SVM for both noiseless and noisy PQ signals.
F. Tootoonchian, F. Zare,
Volume 14, Issue 3 (9-2018)
Abstract
Disk Type Variable Reluctance (DTVR) resolvers have distinguished performance under run out fault comparing to conventional sinusoidal rotor resolvers. However, their accuracy under inclined rotor fault along with different types of eccentricities includes static and dynamic eccentricities are questioned. Furthermore, due to thin copper wires that are used for signal and excitation coils of resolver there is high risk of short circuit fault in the coils. So, in this study the performance of the sinusoidal rotor DTVR resolver under the mentioned faults are studied. The quality of output voltages along with position error of the sensor is discussed. 3-D time stepping finite element method is used to show the effect of different faults. Finally, the prototype of the studied resolver is constructed and tested. The employed test bed is built in such a way that is able to apply controllable level of different mechanical faults. Good agreement is obtained between the finite element and the experimental results, validating the success of the presented analysis.
S. Mohammad Nejad, H. Arab, N. Ronagh Sheshkelani,
Volume 14, Issue 3 (9-2018)
Abstract
In this paper, after a brief overview on laser warning system (LWS), a new structure for an optical array that is used in its optical subsystem is introduced. According to the laser threats’ wavelengths (0.5 – 1.6 µm) and our desirable field of view (FOV), we used 6 lenses for gathering the incident radiation and then optimized the optical array. Lenses’ radius, their semi diameter, their distance from each other, their thickness and the kind of glass used in them was chosen in which we access a very high transmission coefficient. Also the optical reflection and absorption of the array decreases at the same time. After optimization, the obtained optical transmission in our desirable FOV is up to 82% and the obtained optical reflection and absorption is less than 15%. Total aberration of the incident ray decreased notably and the results showed that this parameter is less than 2µm. The laser spot diameter which is focused on the detector is smaller than 400 µm in the worst case which is the laser radiation with 1.54 µm wavelength and field of 10 degrees. Total track of the array is 66.819 mm and effective focal length and F/# parameter are as small as possible which leads to high quality of the light’s focus on the detector and smaller dimension and lighter weight for the receiver. Using optical devices with such appropriate arrangement and very good optical transmission coefficient, the offered structure has a remarkable signal to noise ratio (SNR) which is up to 160 dB. The receiver’s operation in far distances from laser sources (beyond 15 km) and in hazy conditions and low temperatures is quite suitable as well.
A. Jabbari,
Volume 14, Issue 3 (9-2018)
Abstract
Brushless permanent magnet surface inset machines are interested in industrial applications due to their high efficiency and power density. Magnet segmentation is a common technique in order to mitigate cogging torque and electromagnetic torque components in these machines. An accurate computation of magnetic vector potential is necessary in order to compute cogging torque, electromagnetic torque, back electromotive force and self/mutual inductance. A 2D analytical method for magnetic vector potential calculation in inner rotor brushless segmented surface inset permanent magnet machines is proposed in this paper. The analytical method is based on the resolution of Laplace and Poisson equations as well as Maxwell equation in a quasi- Cartesian polar coordinate by using sub-domain method. One of the main contributions of the paper is to derive an expression for the magnetic vector potential in the segmented PM region by using hyperbolic functions. The developed method is applied on the performance computation of two prototype surface inset magnet segmented motors with open circuit and on load conditions. The results of these models are validated through FEM method.
M. Evazi, M. Shahsavan, M. Heidari, A. Razminia,
Volume 14, Issue 4 (12-2018)
Abstract
This paper addresses a new method for decreasing error in secure chaotic communication which utilizes an adaptive law in demodulator part. The basic tools in this process are the Total Least Square as the fundamental technique in demodulating section and a chaotic signal as the carrier one which impose some complexities on the overall system. This algorithm may be used in digital filter for estimating parameters with lower error. Using this approach an improvement can be achieved in estimating the desired signal in comparison with two famous methods, namely, ordinary Least Mean Square (LMS) and Constrained-Stability LMS (CS-LMS). An illustrative example has been used to verify the presented technique through numerical simulation.
M. Tahmasebipour, M. Modarres,
Volume 14, Issue 4 (12-2018)
Abstract
In this paper, a highly sensitive piezoresistive differential pressure microsensor is proposed. This microsensor is consisted of a silicon microcantilever (Length=145 µm; Width=100 µm; Thickness=0.29 µm) and two piezoresistors were mounted (via proper connections) on the microsensor for measuring the created pressure difference. Applying pressure to the microcantilever induces longitudinal and transverse stresses in the piezoresistors, changing their electric resistance and, consequently, the output voltage in the reading circuit of the microsensor. Longitudinal and transverse stresses, different relative sensor resistances resulting from different pressures, voltage variations along the piezoresistors, and microcantilever deflection resulting from different pressures were investigated. To improve the sensor sensitivity, effect of doping concentration, piezoresistors width, and the width of the structure placed under the piezoresistors were studied. In addition, we studied how increasing the width and length of the beam influenced the sensitivity of the sensor. Based on analysis results, the sensor sensitivity was increased from 0.26 W/Pa to 15.78 W/Pa (~60 times). To evaluate the behavior and performance of the proposed microsensor, the following characteristics were analyzed: maximum microcantilever displacement, von Mises stress distribution along the beam and microsensor resistance variations.
O. Herbadji, L. Slimani, T. Bouktir,
Volume 15, Issue 1 (3-2019)
Abstract
In this study, a multiobjective optimization is applied to Optimal Power Flow Problem (OPF). To effectively achieve this goal, a Multiobjective Ant Lion algorithm (MOALO) is proposed to find the Pareto optimal front for the multiobjective OPF. The aim of this work is to reach good solutions of Active and Reactive OPF problem by optimizing 4-conflicting objective functions simultaneously. Here are generation cost, environmental pollution emission, active power losses, and voltage deviation. The performance of the proposed MOALO algorithm has been tested on various electrical power systems with different sizes such as IEEE 30-bus, IEEE 57-bus, IEEE 118-bus, IEEE 300-bus systems and on practical Algerian DZ114-bus system. The results of the tests proved the versatility of the algorithm when applied to large systems. The effectiveness of the proposed method has been confirmed by comparing the results obtained with those obtained by other algorithms given in the literature for the same test systems.
V. Abbasi, S. Hemmati, M. Moradi,
Volume 15, Issue 1 (3-2019)
Abstract
Stress grading (SG) layer in cable terminations limits the critical electric field and properties of SG materials are important issues which have to be considered during manufacturing and selecting procedure. In this paper, two different types of (SG) materials are analyzed by both theory and test. According to the applied theory, important parameters as: electrical resistivity, breakdown voltage and thermal conductivity are determined by experiments. Experimental steps are defined in the paper with which theory and experiments are matched together to complete the investigation. The paper discusses electro-thermal breakdown theory and quality of two different SG layers based on the test results. The theory and experimental procedure can be used for prediction of breakdown voltage in cable terminations. The employed method is useful for qualifying the cable terminations by users who want to buy and install heat shrink cable terminations.
M. A. Trimukhe, B. G. Hogade,
Volume 15, Issue 2 (6-2019)
Abstract
In this paper a particle swarm optimization (PSO) algorithm is presented to design a compact stepped triangle shape antenna in order to obtain the proper UWB bandwidth as defined by FCC. By changing the various cavity dimensions of the antenna, data to develop PSO program in MATLAB is achieved. The results obtained from the PSO algorithm are applied to the antenna design to fine-tune the bandwidth. Bandwidth optimization for ultra-wideband frequency of 3.1 GHz to 10.6 GHz is achieved by applying PSO algorithm. High-Frequency Structure Simulator (HFSS) software tool is used for the simulation. An optimized antenna is fabricated, tested and test results are found in accordance with simulation results.
