Shahriar Shirvani Moghaddam
Volume 5, Issue 1 , Winter and Spring 2017, , Pages 0-0
Volume 5, Issue 2 , Summer and Autumn 2017, , Pages 0-0
Volume 6, Issue 2 , Summer and Autumn 2018, , Pages 0-0
Volume 6, Issue 1 , Winter and Spring 2018, , Pages 0-0
Z. Ghassemlooy; D. Wu; M. A. Khalighi; X. Tang
Volume 1, Issue 1 , Winter and Spring 2013, , Pages 1-9
Abstract
For an indoor non-directed line of sight optical wireless communication (NLOS-OWC) system we investigate the optimized Lambertian order (OLO) of light-emitting diodes (LEDs). We firstly derive an expression for the OLO from a conventional Lambertian LED model. Then, we analyze the indoor multi-cell NLOS-OWC ...
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For an indoor non-directed line of sight optical wireless communication (NLOS-OWC) system we investigate the optimized Lambertian order (OLO) of light-emitting diodes (LEDs). We firstly derive an expression for the OLO from a conventional Lambertian LED model. Then, we analyze the indoor multi-cell NLOS-OWC channel characteristics including the optical power distribution and the multipath time dispersion for two cases of one-cell and four-cell configurations. Furthermore, we estimate the transmission bandwidth by simulating the channel frequency response. Numerical results presented show that, by using OLO a significant improvement of the transmission bandwidth can be achieved for an indoor NLOS-OWC system, in particular, for multi-cell configurations.
P. Amiri; M. Kohestani; M. Seifouri
Volume 2, Issue 1 , Winter and Spring 2014, , Pages 1-5
Abstract
In this paper, we investigate the parameters affecting Total Harmonic Distortion (THD) and Power Supply Rejection Ratio (PSRR) in PWM Class D Amplifiers (CDAs) on the basis of linear models with feedback. From our mathematical analysis, we show that the THD of a PWM Class D amplifier with feedback can ...
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In this paper, we investigate the parameters affecting Total Harmonic Distortion (THD) and Power Supply Rejection Ratio (PSRR) in PWM Class D Amplifiers (CDAs) on the basis of linear models with feedback. From our mathematical analysis, we show that the THD of a PWM Class D amplifier with feedback can be improved by increasing the gain of the integrator through adding another amplifier at the output of the integrator. We also show that the THD can be further improved by means of two cascaded amplifiers with a single pole. We verify our analysis by means of PSPICE simulations. Simulation results show that the THD of the gain boosting and the two cascaded amplifiers with a single pole CDAs can be improved by as much as 1.4 times and 2 times, respectively.
M. Mansour Abadi; Z. Ghassemlooy; D. Smith; W. Pang Ng
Volume 3, Issue 1 , Winter and Spring 2015, , Pages 1-11
Abstract
Studying Gaussian beam is a method to investigate laser beam propagation and ABCD matrix is a fast and simple method to simulate Gaussian beam propagation in different mediums. Of the ABCD matrices studied so far, reflection and refraction matrices at various surfaces have attracted a lot of researches. ...
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Studying Gaussian beam is a method to investigate laser beam propagation and ABCD matrix is a fast and simple method to simulate Gaussian beam propagation in different mediums. Of the ABCD matrices studied so far, reflection and refraction matrices at various surfaces have attracted a lot of researches. However in previous work the incident beam and the principle axis of surface are in parallel. As an extension to those investigations, a general scheme that the incident beam is oblique is discussed here and the full analysis of the reflection and refraction of a Gaussian beam at the surface of a tilted concave/convex elliptic paraboloid surface is addressed. Based on the optical phase matching, analytic mathematical equations are derived for the spot size and the wavefront radius of a beam. Expressions are converted into the ABCD matrices, which are more convenient and practical to use. Finally, a practical case is analyzed by applying the obtained formulas. This analysis is important since paraboloid surfaces in optics or terahertz waves are used as mirrors or lenses.
V. Maihami; F. Yaghmaee
Volume 4, Issue 1 , Winter and Spring 2016, , Pages 1-8
Abstract
With quick development of digital images and the availability of imaging tools, massive amounts of images are created. Therefore, efficient management and suitable retrieval, especially by computers, is one of themost challenging fields in image processing. Automatic image annotation (AIA) or refers ...
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With quick development of digital images and the availability of imaging tools, massive amounts of images are created. Therefore, efficient management and suitable retrieval, especially by computers, is one of themost challenging fields in image processing. Automatic image annotation (AIA) or refers to attaching words, keywords or comments to an image or to a selected part of it. In this paper, we propose a novel image annotation algorithm based on neighbor voting which uses fuzzy system. The performance of the model depends on selecting the right neighbors and a fuzzy system with the right combination of features it offers.Experimental results on Corel5k and IAPR TC12 benchmark annotated datasets, demonstrate that using the proposed method leads to good performance.
S. Jamali; N. Alipasandi; B. Alipasandi
Volume 2, Issue 2 , Summer and Autumn 2014, , Pages 57-61
Abstract
Random Early Detection (RED) is one of the most commonly used Active Queue Management (AQM) algorithms that is recommended by IETF for deployment in the network. Although RED provides low average queuing delay and high throughput at the same time, but effectiveness of RED is highly sensitive to the RED ...
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Random Early Detection (RED) is one of the most commonly used Active Queue Management (AQM) algorithms that is recommended by IETF for deployment in the network. Although RED provides low average queuing delay and high throughput at the same time, but effectiveness of RED is highly sensitive to the RED parameters setting. As network condition varies largely, setting RED's parameters with fixed values is not an efficient solution. We propose a new method to dynamically tuning RED's parameters. For this purpose, we compute the rate of which the queue is occupied and consider it as a congestion metric that will be forecasted when the queue is overloaded. This meter is used to dynamically setting RED parameters. The simulation results show the effectiveness of the proposed method. According to the results, we achieve a significantly higher utilization and less packet loss comparing to original RED algorithm in dynamic conditions of the network.
T. G. Arora; M. V. Aware; D. R. Tutakne
Volume 1, Issue 2 , Summer and Autumn 2013, , Pages 63-71
Abstract
Pulse-width modulated (PWM) adjustable frequency drives (AFDs) are extensively used in industries for control of induction motors. It has led to significant advantages in terms of the performance, size, and efficiency but the output voltage waveform no longer remains sinusoidal. Hence, overshoots, high ...
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Pulse-width modulated (PWM) adjustable frequency drives (AFDs) are extensively used in industries for control of induction motors. It has led to significant advantages in terms of the performance, size, and efficiency but the output voltage waveform no longer remains sinusoidal. Hence, overshoots, high rate of rise, harmonics and transients are observed in the voltage wave. They increase voltage and thermal stresses; resulting into accelerated insulation aging. This paper presents the application of fuzzy logic to life estimation of PWM driven induction motors. Insulation stress parameters are experimentally computed for wide range of switching frequency and used in fuzzy logic based life estimation algorithms. The results obtained with the fuzzy expert system show a performance approaching that attainable for the life model based on the inverse power law.
J. Rostami Monfared; M. Fazeli; Y. Lotfi
Volume 3, Issue 2 , Summer and Autumn 2015, , Pages 71-75
Abstract
In this article, a speed control of DC motor is designed and illustrated using fuzzy logic-based programmable logic controller (PLC). The DC motor is an attractive part of electrical equipment in many industrial applications requiring variable speed and load specifications due to its ease of controllability. ...
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In this article, a speed control of DC motor is designed and illustrated using fuzzy logic-based programmable logic controller (PLC). The DC motor is an attractive part of electrical equipment in many industrial applications requiring variable speed and load specifications due to its ease of controllability. The designed system is consisted of three main parts including programmable logic controller, pulse width modulation (PWM) bipolar drive and DC motor. In the control section, PLC is used as real time controller and fuzzy logic algorithm is designed based on nonlinear model of DC motor, and its parameters are optimized in MATLAB software. Then, it is implemented using rslogix5000 PLC and programming language ladder for speed control. Finally, with favorable results, the efficiency of the controller is successfully proved under different load conditions. The obtained results demonstrate the efficiency of the PLC intelligent controller in enhancing the accuracy and speed control of DC motor.
S. Roostaee; H.R Ghaffary
Volume 4, Issue 2 , Summer and Autumn 2016, , Pages 105-110
Abstract
Data analysis in cardiovascular diseases is difficult due to large massive of information. All of features are not impressive in the final results. So it is very important to identify more effective features. In this study, the method of feature selection with binary cuckoo optimization algorithm is ...
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Data analysis in cardiovascular diseases is difficult due to large massive of information. All of features are not impressive in the final results. So it is very important to identify more effective features. In this study, the method of feature selection with binary cuckoo optimization algorithm is implemented to reduce property. According to the results, the most appropriate classification for support vector machine is featured diagnoses heart disease. The main purpose of this article is feature reduction and providing a more precise diagnosis of the disease. The proposed method is evaluated using three measures: accuracy, sensitivity and specificity. For comparison, a data set of Machine Learning Repository database including information about 303 people with 14 features was used. In addition to the high accuracy of current methods, are expensive and time-consuming. The results indicate that the proposed method is superior on other algorithms in terms of Performance, accuracy and run time.
Network Security
M. Amiri; A. Barati
Articles in Press, Corrected Proof, Available Online from 01 November 2019
Abstract
Increasing usage of Internet and computer networks by individuals and organizations and also attackers’ usage of new methods and tools in an attempt to endanger network security, have led to the emergence of a wide range of threats to networks. A honeypot is one of the basic techniques employed ...
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Increasing usage of Internet and computer networks by individuals and organizations and also attackers’ usage of new methods and tools in an attempt to endanger network security, have led to the emergence of a wide range of threats to networks. A honeypot is one of the basic techniques employed for network security improvement. It is basically designed to be attacked so as to get the attackers’ information and trap them. By using a vulnerable scanner in this paper, we obtained the required network vulnerabilities and normalized them via the proposed method. Then, a dynamic hybrid honeypot has proposed by high and low interaction honeypots. Also, in the proposed method, by footprinting and scanning of an integrated network, a detailed picture of the production network and a honeypot configuration file are generated. As a result, more devices could be detected via automated production by the proposed method. This method could accelerate honeypot production and reduce the users’ mistakes during their manual production. Monitoring network traffic, collecting the information of network machines, determining network operating systems, and storing data in a database are the specific features of this system that could be performed by using the selected network scanning tools and modules.
Volume 7, Issue 1 , Winter and Spring 2019
M. Zahiry; S.M. Hashemi; J. Ghalibafan
Volume 5, Issue 1 , Winter and Spring 2017, , Pages 1-6
Abstract
In this paper, a new method for designing an active dual-band dipole antenna is proposed. The operating frequencies of the proposed antenna are 150 and 450 MHz that are usually used in military applications. Using a series stub is the main idea in the proposed dual-band antenna, where it makes an independent ...
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In this paper, a new method for designing an active dual-band dipole antenna is proposed. The operating frequencies of the proposed antenna are 150 and 450 MHz that are usually used in military applications. Using a series stub is the main idea in the proposed dual-band antenna, where it makes an independent resonance frequency higher than the main resonance frequency of a conventional dipole. To make appropriate matching impedance in the two frequency bands, the technique of creating an internal coaxial cable is used. Furthermore, to improve the antenna gain, an amplifier is in series part connected to the proposed dipole antenna. The simulated and measured results of the return loss, radiation patterns and antenna gain show that this antenna has a good operation in both resonance frequencies.
S. Ranjbaran; A. Roudbari; S. Ebadollahi
Volume 6, Issue 1 , Winter and Spring 2018, , Pages 1-6
Abstract
Using field calibration methods without precision laboratory equipment, systematic faults of inertial sensors can be reduced and measurement accuracy can be increased. In this paper, a simple and fast method called improved least squares is used to find calibration coefficients of an accelerometer including ...
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Using field calibration methods without precision laboratory equipment, systematic faults of inertial sensors can be reduced and measurement accuracy can be increased. In this paper, a simple and fast method called improved least squares is used to find calibration coefficients of an accelerometer including bias, scale factor and non-orthogonality. Simulation results show that the measurement accuracy has improved by about 60%. In this method, this principal is used that the magnitude of acceleration measured by accelerometer in static condition is equal to the magnitude of gravity vector and a cost function is then defined. Also, in gyroscope field calibration, sensor is rotated manually around all three axes separately and then it is put in the static mode. Changes in the angle obtained from gyroscope at each movement are compared with the ones obtained from the calibrated accelerometer. Calibration coefficients including bias and scale factor are obtained using least squares method. Simulation results show that accuracy of the gyroscope has increased by about 40% and comparison with the other methods proves that the proposed method performs well.
Power
H. Amiri; G. Arab Markadeh; N. Mahdian
Volume 7, Issue 1 , Winter and Spring 2019, , Pages 1-10
Abstract
Increasing DC loads along with DC nature of distributed energy resources (DERs) raises interest to DC microgrids. Conventional droop/non-droop power-sharing in microgrids suffers from load dependent voltage deviation, slow transient response, and requires the parameters of the loads, system and DERs ...
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Increasing DC loads along with DC nature of distributed energy resources (DERs) raises interest to DC microgrids. Conventional droop/non-droop power-sharing in microgrids suffers from load dependent voltage deviation, slow transient response, and requires the parameters of the loads, system and DERs connection status. In this paper, a new nonlinear decentralized back-stepping control strategy for voltage control and load sharing of DC islanded microgrids is proposed. The proposed method is robust against the load variations and uncertainty in microgrid parameters and has excellent dynamic and steady-state performance under different operating conditions. The major purpose of the proposed controller is to improve the transient performance of MG with load variations and constant power loads (CPLs). The local controller regulates the terminal voltage of DC-DC converter regarding the local quantities without needs to additional data of other system components. For simplicity, the proposed method is simulated with PSIM software on a DC microgrid with two DGs. Different scenarios are studied to present the performance of the proposed method under different operating conditions. The results indicate the capability of the proposed method for voltage control and load sharing in DC microgrids.
S. SamadiGorji; B. Zakeri; M.R. Zahabi
Volume 2, Issue 1 , Winter and Spring 2014, , Pages 7-13
Abstract
The aim of this paper is to minimize output phase noise for the pure signal synthesis in the frequency synthesizers. For this purpose, first, an exact mathematical model of phase locked loop (PLL) based frequency synthesizer is described and analyzed. Then, an exact closed-form formula in terms of synthesizer ...
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The aim of this paper is to minimize output phase noise for the pure signal synthesis in the frequency synthesizers. For this purpose, first, an exact mathematical model of phase locked loop (PLL) based frequency synthesizer is described and analyzed. Then, an exact closed-form formula in terms of synthesizer bandwidth and total output phase noise is extracted. Based on this formula, the phase noise diagram as a function of bandwidth is plotted. From the analysis and simulation results, it is observed that the synthesizer has a minimum phase noise at a particular bandwidth.
S. Taghipour; R. Niaraki Asli
Volume 4, Issue 1 , Winter and Spring 2016, , Pages 9-14
Abstract
Due to the expected increase of defects in circuits based on deep submicron technologies, reliability has become an important design criterion. Although different approaches have been developed to estimate reliability in digital circuits and some measuring concepts have been separately presented to reveal ...
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Due to the expected increase of defects in circuits based on deep submicron technologies, reliability has become an important design criterion. Although different approaches have been developed to estimate reliability in digital circuits and some measuring concepts have been separately presented to reveal the quality of analog circuit reliability in the literature, there is a gap to estimate reliability when circuit includes analog and digital structures. In this paper, we propose a new classification method using Monte Carlo analysis to calculate the reliability of analog circuits and show its efficacy when it is used for a combination of analog and digital circuits. Our method is based on signal reliability concepts and measures the probability of passing correct or faulty values. Furthermore, we compare our reliability measurements with the reliability definitions come from other failure mechanisms in sub-micron technologies. Simulation results show the reliability measurement presented here which provides key information for reliability improvement and monitoring.
A. Safaei; M. Jahed
Volume 1, Issue 1 , Winter and Spring 2013, , Pages 11-18
Abstract
Gesture and motion recognition are needed for a variety of applications. The use of human hand motions as a natural interface tool has motivated researchers to conduct research in the modeling, analysis and recognition of various hand movements. In particular, human-computer intelligent interaction has ...
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Gesture and motion recognition are needed for a variety of applications. The use of human hand motions as a natural interface tool has motivated researchers to conduct research in the modeling, analysis and recognition of various hand movements. In particular, human-computer intelligent interaction has been a focus of research in vision-based gesture recognition. In this work, we introduce a 3-D hand model recognition method that offers flexible and elaborate representation of hand motion. We used landmark points on the tips and joints of the fingers and calculated the 3-D coordinates of these points through a stereo vision system followed by a Hidden Markov Model (HMM) to recognize hand motions. Experimentally, in an effort to evaluate the formation of hand gestures similar to those used in rehabilitation sessions, we studied three evolving motions. Given the natural hand features and uncontrolled environment, we were able to classify and differentiate unnatural slowness or rapidness in the performance of such motions, ranging from 45% to 93%.
E. Rafiee; F. Emami
Volume 3, Issue 1 , Winter and Spring 2015, , Pages 13-16
Abstract
In this paper, effects of the structural parameters on the optical characteristics of an add-drop filter, consisting of two straight waveguides and a micro-ring resonator (MRR), have been investigated. In this research, effects of MRR radius, the width of MRR and waveguide and the gap between MRR and ...
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In this paper, effects of the structural parameters on the optical characteristics of an add-drop filter, consisting of two straight waveguides and a micro-ring resonator (MRR), have been investigated. In this research, effects of MRR radius, the width of MRR and waveguide and the gap between MRR and waveguide, on free spectral range (FSR) and coupling coefficient have been studied. It is found thatby enhancing the gap and width, coupling coefficient would be increased at first but after a while it would be decreased. It is also shown that, increasing the radius and width would decrease FSR. The main goal of this research is to decrease FSR and increase the coupling coefficient of add-drop filters, which are widely used in communication applications.
M. Hafezi_Nasab; M. Rashidinejad; A. Abdollahi; I. Taheri
Volume 2, Issue 2 , Summer and Autumn 2014, , Pages 63-68
Abstract
In this paper, the concept of Conjectural Variation (CV) is used to specify optimal generation decision for generation companies (Gencos). The conjecture of Genco is defined as its belief or expectation about the reaction of rivals to change of its output. Using CV method, each Genco has to learn and ...
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In this paper, the concept of Conjectural Variation (CV) is used to specify optimal generation decision for generation companies (Gencos). The conjecture of Genco is defined as its belief or expectation about the reaction of rivals to change of its output. Using CV method, each Genco has to learn and estimate strategic behaviors of other competitors from available historical market operation data. Therefore, accuracy of generation decision depends on the accuracy of estimating other competitors’ decision within CV context. In this paper, adjusted Lerner index is used to improve the accuracy of estimating CV parameter. In electricity market, the adjusted Lerner index can be directly computed using price, market shares, marginal cost and industry elasticity of demand. It must be noted that due to repeated power market, Gencos need to modify their behavior over time. In response to this need, dynamic learning is considered in case studies which improve results.
P. Amiri; M. Sharafi
Volume 1, Issue 2 , Summer and Autumn 2013, , Pages 73-81
Abstract
This paper presents a novel control method to improve the efficiency of low-voltage DC-DC converters at light loads. Pulse Width Modulation (PWM) converters have poor efficiencies at light loads, while pulse frequency modulation (PFM) control is more efficient for the same cases. Switching losses constitute ...
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This paper presents a novel control method to improve the efficiency of low-voltage DC-DC converters at light loads. Pulse Width Modulation (PWM) converters have poor efficiencies at light loads, while pulse frequency modulation (PFM) control is more efficient for the same cases. Switching losses constitute a major portion of the total power loss at light loads. To decrease the switching losses and to increase efficiency, converters based on soft-switching are utilized. This paper presents the design of a soft-switching DC-DC buck converter in a 90-nm CMOS technology. Simulation results by HSPICE shows a 21 mV output ripple on a 0.5 V output voltage for an input voltage of 1.4 V. Finally, the efficiency of 95% at a load current of 50 mA having 74 mA of current ripple is achievable.
A. Tabandeh; A. Abdollahi; M. Rashidinejad
Volume 3, Issue 2 , Summer and Autumn 2015, , Pages 77-88
Abstract
Under the smart grid environment, demand response resources (DRRs) are introduced as a virtual power plant to enhance power system adequacy. DRRs often fail to reduce their load due to some external factors. In this paper, a reliability model of a DRR is constructed as multi-state conventional generation ...
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Under the smart grid environment, demand response resources (DRRs) are introduced as a virtual power plant to enhance power system adequacy. DRRs often fail to reduce their load due to some external factors. In this paper, a reliability model of a DRR is constructed as multi-state conventional generation units, where the probability, frequency of occurrence, and departure rate of each state can be acquired. DRRs as consequence of demand response program implementation can be applied to transmission congestion management. Therefore, this paper presents an optimal model of congestion management (CM) by means of multi-state DRRs, namely CM_DRR. In the proposed approach, in addition to DRRs, independent system operator relieves the existing transmission line congestions using the combination of generating unit rescheduling and involuntary load shedding. The hourly historical data associated with the Connecticut region in New England is employed to achieve the DRRs’ participation regime. Moreover, the impact of different capacities of DRRs on the congestion management cost and load shedding cost is evaluated. Results of applying the aforementioned model to the 24-bus Reliability Test System (RTS) indicate the efficiency of CM_DRR framework.
M. Moradi; M.R. Sadeghi
Volume 5, Issue 2 , Summer and Autumn 2017, , Pages 93-100
Abstract
One of the serious issues in communication between people is hiding information from the others, and the best way for this, is to deceive them. Since nowadays face images are mostly used in three dimensional format, in this paper we are going to steganography 3-D face images and detecting which by curious ...
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One of the serious issues in communication between people is hiding information from the others, and the best way for this, is to deceive them. Since nowadays face images are mostly used in three dimensional format, in this paper we are going to steganography 3-D face images and detecting which by curious people will be impossible. As in detecting face only, its texture is important, we separate texture from shape matrices, for eliminating half of the extra information. Steganography is done only for face texture, and for reconstructing a 3-D face, we can use any other shape. Moreover, we will indicate that, by using two textures, how two 3-D faces can be combined. For a complete description of the process, first, 2-D faces are used as an input for building 3-D faces, and then 3-D face and texture matrices are extracted separately from the constructed 3-D face. Finally, 3-D textures are hidden within the other images.
