frequency

Open Access Article

1 - A Survey to the Narrative Time in the Play of "Moonlight Women, Sunny Man"
مهدی نیک‌منش سونا سلیمیان

In the few decades that narratology has been introduced as a science, narratologists have tried to explore its universal structure by finding specific narrative patterns for different aspects of story writing, including narrative time. The French theorist, Gerard Genett More

In the few decades that narratology has been introduced as a science, narratologists have tried to explore its universal structure by finding specific narrative patterns for different aspects of story writing, including narrative time. The French theorist, Gerard Genette, has posed an autonomous theory on "the parameter of time and its function and place in narration". According to him, timing arrangement in a narration is got through order, duration, and frequency. Studying and contrasting them against real time, one can determine the place of time in the process of story. Studying narrative time of in the play of "Moonlight Women, Sunny Man" by Chista Yaserbi shows that Yasrebi, avoiding the usual time sequence, and moving from chronological time to the text time, has made different selections and provided flashback and futurist narratives. Such selections and their especial timing plays a significant role in arranging the components of the plot, as well as suspense. Moerover, studying duration and frequency of the events narrated in this play, shows that the events enjoy an appropriate beat and speed according to the author's purpose. Regarding principles of narratology, there is a direct and significant correlation between content of the play and the speed of narrating the events, their repetition and frequency. Manuscript profile

Open Access Article

2 - Performance Analysis of SVM-Type Per Tone Equalizer Using Blind and Radius Directed Algorithms for OFDM Systems
Babak Haji Bagher Naeeni

10.7508/jist.2013.02.001

In this paper, we present Support Vector Machine (SVM)-based blind per tone equalization for OFDM systems. Blind per tone equalization using Constant Modulus Algorithm (CMA) and Multi-Modulus Algorithm (MMA) are used as the comparison benchmark. The SVM-based cost funct More

In this paper, we present Support Vector Machine (SVM)-based blind per tone equalization for OFDM systems. Blind per tone equalization using Constant Modulus Algorithm (CMA) and Multi-Modulus Algorithm (MMA) are used as the comparison benchmark. The SVM-based cost function utilizes a CMA-like error function and the solution is obtained by means of an Iterative Re-Weighted Least Squares Algorithm (IRWLS). Moreover, like CMA, the error function allows to extend the method to multilevel modulations. In this case, a dual mode algorithm is proposed. Dual mode equalization techniques are commonly used in communication systems working with multilevel signals. Practical blind algorithms for multilevel modulation are able to open the eye of the constellation, but they usually exhibit a high residual error. In a dual mode scheme, once the eye is opened by the blind algorithm, the system switches to another algorithm, which is able to obtain a lower residual error under a suitable initial ISI level. Simulation experiments show that the performance of blind per tone equalization using support vector machine has better than blind per tone equalization using CMA and MMA, from viewpoint of average Bit-Error Rate (BER). Manuscript profile

Open Access Article

3 - GoF-Based Spectrum Sensing of OFDM Signals over Fading Channels
Seyed Sadra Kashef paeez azmi Hamed Sadeghi

10.7508/jist.2014.02.005

Goodness-of-Fit (GoF) based spectrum sensing of orthogonal frequency-division multiplexing (OFDM) signals is investigated in this paper. To this end, some novel local sensing methods based on Shapiro-Wilk (SW), Shapiro-Francia (SF), and Jarque-Bera (JB) tests are first More

Goodness-of-Fit (GoF) based spectrum sensing of orthogonal frequency-division multiplexing (OFDM) signals is investigated in this paper. To this end, some novel local sensing methods based on Shapiro-Wilk (SW), Shapiro-Francia (SF), and Jarque-Bera (JB) tests are first studied. In essence, a new threshold selection technique is proposed for SF and SW tests. Then, three studied methods are applied to spectrum sensing for the first time and their performance are analyzed. Furthermore, the computational complexity of the above methods is computed and compared to each other. Simulation results demonstrate that the SF detector outperforms other existing GoF-based methods over AWGN channels. Furthermore simulation results demonstrate the superiority of the proposed SF method in additive colored Gaussian noise channels and over fading channel in comparison with the conventional energy detector. Manuscript profile

Open Access Article

4 - Optimization of Random Phase Updating Technique for Effective Reduction in PAPR, Using Discrete Cosine Transform
Babak Haji Bagher Naeeni

10.7508/jist.2016.02.004

One of problems of OFDM systems, is the big value of peak to average power ratio. To reduce it, any attempt have been done amongst which, random phase updating is an important technique. In contrast to paper, since power variance is computable before IFFT block, the com More

One of problems of OFDM systems, is the big value of peak to average power ratio. To reduce it, any attempt have been done amongst which, random phase updating is an important technique. In contrast to paper, since power variance is computable before IFFT block, the complexity of this method would be less than other phase injection methods which could be an important factor. Another interesting capability of random phase updating technique is the possibility of applying the variance of threshold power. The operation of phase injection is repeated till the power variance reaches threshold power variance. However, this may be a considered as a disadvantage for random phase updating technique. The reason is that reaching the mentioned threshold may lead to possible system delay. In this paper, in order to solve the mentioned problem, DCT transform is applied on subcarrier outputs before phase injection. This leads to reduce the number of required carriers for reaching the threshold value which results in reducing system delay accordingly. Manuscript profile

Open Access Article

5 - Speech Emotion Recognition Based on Fusion Method
Sara Motamed Saeed Setayeshi Azam Rabiee Arash Sharifi

10.7508/jist.2017.17.007

Speech emotion signals are the quickest and most neutral method in individuals’ relationships, leading researchers to develop speech emotion signal as a quick and efficient technique to communicate between man and machine. This paper introduces a new classification meth More

Speech emotion signals are the quickest and most neutral method in individuals’ relationships, leading researchers to develop speech emotion signal as a quick and efficient technique to communicate between man and machine. This paper introduces a new classification method using multi-constraints partitioning approach on emotional speech signals. To classify the rate of speech emotion signals, the features vectors are extracted using Mel frequency Cepstrum coefficient (MFCC) and auto correlation function coefficient (ACFC) and a combination of these two models. This study found the way that features’ number and fusion method can impress in the rate of emotional speech recognition. The proposed model has been compared with MLP model of recognition. Results revealed that the proposed algorithm has a powerful capability to identify and explore human emotion. Manuscript profile

Open Access Article

6 - Frequency types and their function in the creation of the story
neda nabizadeh ardebili

One of the main elements of every narrative is the element of time, so that narration is based on its timing. Gerard Jenet is the greatest narrative time theorist, who looks at three determinations of order, frequency, and continuity. Frequency, which examines the rep More

One of the main elements of every narrative is the element of time, so that narration is based on its timing. Gerard Jenet is the greatest narrative time theorist, who looks at three determinations of order, frequency, and continuity. Frequency, which examines the repetition of narrative elements, is divided into three single, repeated and recurrent types. In this research, which has been carried out through a library and analytical and descriptive method, we have examined the frequency and function of it in the works of Alawi and Sa'edi. The results of the research show that both authors use different types of frequency in their stories. The dominant frequency on their stories is singular frequency. Other types of frequency are also visible in these works, including frequent frequent functions in these stories, emphasis, expression, space and attention and pity, including the functions of concise frequency in them, the personification and expression of the definition of affairs. In general, it should be said that the operation of frequency types is more diverse in Alawi's works. Manuscript profile

Open Access Article

7 - Study and Realization of an Alarm System by Coded Laser Barrier Analyzed by the Wavelet Transform
meriane brahim Salah Rahmouni Issam Tifouti

10.52547/jist.24198.11.41.57

This article introduces the study and realization of the laser barrier alarm system, after the laser is obtained by an electronic card, the wireless control system is connected to the control room to announce the application in real time, and the laser is used in many a More

This article introduces the study and realization of the laser barrier alarm system, after the laser is obtained by an electronic card, the wireless control system is connected to the control room to announce the application in real time, and the laser is used in many applications fields, from industry to medicine, in this article on the basis of Industrial applications such as laser barrier. It uses an alarm system to detect and deter intruders. Basic security includes protecting the perimeter of a military base or a safety distance in unsafe locations or near a government location. The first stage secures surrounding access points such as doors and windows; The second stage consists of internal detection with motion detectors that monitor movements, In this article, we adopt the embodiment of a coded laser barrier that is transmitted between two units, processes the signal, compares the agreed conditions, and to be high accuracy, we suggest using wavelet transmission to process the received signal and find out the frequencies that achieve alarm activation considering that the transmitted signal They are pulses, but after analysis with a proposed algorithm, we can separate the unwanted frequencies generated by the differential vibrations in order to arrive at a practically efficient system. Manuscript profile

Open Access Article

8 - Application of Combinational Adaptive Load Shedding Schemes to Improve Power System Voltage Stability - Part I: General Concept & the Algorithms
A. Saffarian M. Sanaye-Pasand A. P. Ghaleh

In this paper three combinational adaptive load shedding schemes are proposed to enhance the power system stability especially voltage stability margins of the system following severe events. Nowadays, the security margin of power systems against various instabilities i More

In this paper three combinational adaptive load shedding schemes are proposed to enhance the power system stability especially voltage stability margins of the system following severe events. Nowadays, the security margin of power systems against various instabilities is decreased due to the developments, deregulation and competitions in the power industry. In this situation, traditional system protection schemes can not offer adequate protection especially against combinational events. In some combinational disturbances, after initial frequency drop the conventional protection schemes returns back the system frequency to its permissible values; however, the system eventually collapses due to severe voltage declines which result in voltage instability. In some other disturbances, severe voltage declines cause troubles in appropriate operation of the under frequency load shedding relays. In this paper three adaptive combinational load shedding schemes are proposed to counteract such disturbances. The proposed schemes use locally measured frequency and voltage signals and do not need any communication link. In the proposed algorithms, during under frequency condition, load shedding is started from the locations which have higher voltage decay and for longer period of time. The speed, location and amount of load shedding are changed adaptively depending on the disturbance location, voltage status of the system, and the rate of frequency decline. In the second part of this paper using model of a real network, various simulation studies are performed and performance of the proposed schemes is investigated. Manuscript profile

Open Access Article

9 - Application of Combinational Adaptive Load Shedding Schemes to Improve Power System Voltage Stability - Part II: Simulation Results
A. Saffarian M. Sanaye-Pasand A. P. Ghaleh

paper is part II of a two-part paper. In the first part, several adaptive combinational load shedding schemes were proposed to enhance the power system voltage stability. The main objective of the proposed schemes is to improve the voltage stability margin of the system More

paper is part II of a two-part paper. In the first part, several adaptive combinational load shedding schemes were proposed to enhance the power system voltage stability. The main objective of the proposed schemes is to improve the voltage stability margin of the system following large and combinational disturbances. For major disturbances the frequency and voltage stability of the system are jeopardized simultaneously and the conventional schemes might fail to operate correctly. In this part, the proposed methods are simulated in a real network to evaluate their performance. To achieve realistic results, dynamic model of generators, automatic voltage regulators, governors and loads are considered in the simulations. Considering the importance of load modeling in these studies, the frequency and voltage dependence of static loads have been modeled accurately. Dynamic motor loads have also been modeled using aggregate equivalent induction motors at load buses. Performance of the proposed schemes is compared with each other also with performance of the conventional scheme for various combinational disturbances. Considering the obtained simulation results it is concluded that by using the proposed algorithms the power system becomes more robust against large disturbances and the probability of the power system instability is decreased. Manuscript profile

Open Access Article

10 - Designing a Self-Tuning Frequency Controller Based on ANNs for an Isolated Microgrid
F. Habibi H. Bevrani J. Moshtag

Increasing electrical energy demand, as well as fossil fuel shortages and environmental concerns have caused to use uncommon sources such as distributed generations (DGs) and renewable energy sources (RESs) into modern power systems. A microgrid (MG) system consists of More

Increasing electrical energy demand, as well as fossil fuel shortages and environmental concerns have caused to use uncommon sources such as distributed generations (DGs) and renewable energy sources (RESs) into modern power systems. A microgrid (MG) system consists of several DGs and RESs which is responsible to provide both electrical and heat powers for local loads. Due to the MGs nonlinearity/complexity which is imposed to the conventional power systems, classical and nonflexible control structures may not represent desirable performance over a wide range of operating conditions. Therefore, more flexible/intelligent control methods are needed most of the past. Hence, in this paper addresses to design an online/self-tuning PI-controller based on artificial neural networks (ANNs) for optimal regulating the MG systems frequency. Manuscript profile

Open Access Article

11 - Introducing a New Actuation Signal to Improve the Reliability of Capacitive RF MEMS Switch
M. Zarghami Y. Mafinejad M. Zarghami Kh. Mafinezhad

In this paper a modified novel dual pulse actuation signal has been proposed to reduce dielectric charging in microelectromechanical system switches. The waveform has a significant impact in reducing the dielectric charging; therefore the amount of charge density in the More

In this paper a modified novel dual pulse actuation signal has been proposed to reduce dielectric charging in microelectromechanical system switches. The waveform has a significant impact in reducing the dielectric charging; therefore the amount of charge density in the proposed waveform has decreased 7.2% than the dual pulse waveform, although the newest waveform (novel dual pulse) has shown a 5% reduction in dielectric charging. So, the proposed actuation signal waveform will increase the lifetime of switch. We utilized mathematical and transient circuit models to calculate the amount of charge density in the dielectric and finally, the new actuation signal waveform has shown better performance than the other prevalent actuation signal waveforms. Manuscript profile

Open Access Article

12 - A New Pulse Frequency Waveform Synthesizing Method Using IPT Frequency-Gain Characteristics
M. H. Ameri A. Yazdian Varjani M. Mohamadian

The electrical connection between the load and source can be eliminated using inductive power transfer. Supplying AC Loads, such as V2G and single phase motors, is one of the many applications of IPT. To supply an AC load, the rectified output power of IPT should be del More

The electrical connection between the load and source can be eliminated using inductive power transfer. Supplying AC Loads, such as V2G and single phase motors, is one of the many applications of IPT. To supply an AC load, the rectified output power of IPT should be delivered to an inverter. The sequential dc/ac/dc/ac conversions cause IPT efficiency decreases. To make an output AC voltage with acceptable THD, the carrier frequency of the PWM method should be several times the reference frequency which increases the switching loss. In this paper based on IPT gain-frequency characteristics, a new pulse frequency waveform synthesizing method (PFWS) has been presented. This method eliminates secondary inverter switching losses. It is shown that besides loss reduction, synthesized sinusoidal waveform at secondary of IPT, causes the Total Switching Device Power (TSDP) of secondary converters decrease, therefore their lifetime increase. Simulated and experimental results of the developed laboratory model which verify and illustrate the operation of the proposed method are presented. Manuscript profile

Open Access Article

13 - Upper and Lower Bounds on ICI Power of FrFT-OFDM Systems in Frequency Selective Time Varying Channels
Z. Mokhtari M. Sabbaghian

In this paper, we study the inter carrier interference (ICI) in fractional Fourier transform based orthogonal frequency division multiplexing (FrFT-OFDM) systems. In this analysis, we derive tight upper and lower bounds for ICI power of FrFT-OFDM systems in doubly dispe More

In this paper, we study the inter carrier interference (ICI) in fractional Fourier transform based orthogonal frequency division multiplexing (FrFT-OFDM) systems. In this analysis, we derive tight upper and lower bounds for ICI power of FrFT-OFDM systems in doubly dispersive channels. These bounds have considerably simpler expressions than the exact ICI formula. Thus, they provide deep and useful insight into the effect of Doppler frequency, symbol duration, channel delay spread, and angle of transform on the ICI power. This analysis confirms that in the special case of flat fast fading channels the FrFT-OFDM and Fourier transform based OFDM (FT-OFDM) systems exhibit analogous performance while in doubly dispersive channels FrFT-OFDM can achieve better performance than single carrier (SC) and FT-OFDM, if the angle of transform is selected accurately. Manuscript profile

Open Access Article

14 - Double Recycling Folded Cascode Op-Amp Using Feed-Forward Capacitor Coupling Driving
Mohammad R. Ali Ali Khamesi Naeini

A double recycling Op-Amp based on a simple recycling folded cascode Op-Amp is presented. The proposed Op-Amp has significantly improved performance compared to a recycling folded cascode. In the proposed Op-Amp, those cascode output current sources of recycling folde More

A double recycling Op-Amp based on a simple recycling folded cascode Op-Amp is presented. The proposed Op-Amp has significantly improved performance compared to a recycling folded cascode. In the proposed Op-Amp, those cascode output current sources of recycling folded cascode that still have a constant value have been considered and have taken on a dynamic state through capacitive couplings in the path created between the input and output of the amplifier. DC gain, unity-gain bandwidth, and slew rate have been improved compared to the previous amplifier at the same power consumption. Simulation results using the 0.18μm CMOS technology show a DC gain enhancement of 6dB, 35% improvement in slew rate, and almost a 30% increase the bandwidth compared to the traditional recycling folded cascode Op-Amp. Also, smaller input-referred noise is achieved. Simulated results of proposed circuit show the values of SR, power consumption and DC gain are about 93.5 V/µs, 1.02mW and 68.3 dB respectively. Manuscript profile

Open Access Article

15 - Spectrum Sensing of OFDM Signals Utilizing Higher Order Statistics under Noise Uncertainty Environments in Cognitive Radio Systems
MOUSUMI HAQUE Tetsuya Shimamura

10.61186/jist.37961.11.43.251

Cognitive radio (CR) is an important issue to solve the spectrum scarcity problem for modern and forthcoming wireless communication systems. Spectrum sensing is the ability of the CR systems to sense the primary user signal to detect an ideal portion of the radio spectr More

Cognitive radio (CR) is an important issue to solve the spectrum scarcity problem for modern and forthcoming wireless communication systems. Spectrum sensing is the ability of the CR systems to sense the primary user signal to detect an ideal portion of the radio spectrum. Spectrum sensing is mandatory to solve the spectrum scarcity problem and the interference problem of the primary user. Noise uncertainty consideration for orthogonal frequency division multiplexing (OFDM) transmitted signals in severe noise environments is a challenging issue for measuring the performance of spectrum sensing. This paper proposed a method using higher order statistics (HOS) functions including skewness and kurtosis for improving the sensing performance of a cyclic prefix (CP) based OFDM transmitted signal for noise uncertainty. The detection performance of OFDM systems is measured for various CP sizes using a higher order digital modulation technique over a multipath Rayleigh fading channel for low signal-to-noise ratio (SNR) cases. In the proposed method, the CP-based OFDM transmitted signal sensing performance is measured and compared with the conventional methods under noise uncertainty environments. Through comprehensive evaluation of simulation, it is demonstrated that the sensing performance of this method significantly outperforms conventional schemes in the case of noise uncertainty in severe noise environments. Manuscript profile

Open Access Article

16 - Investigating the performance of electronic transformers on the environment
Maziar Demory Nejad Mehrdad Mohadpur

During the last 30 and 40 years, TS transformer substations have evolved a lot, from the classic assembly in open areas, partition walls and outdoors, to the existing model, in order to increase human safety and material reliability, as well as significant progress. Ass More

During the last 30 and 40 years, TS transformer substations have evolved a lot, from the classic assembly in open areas, partition walls and outdoors, to the existing model, in order to increase human safety and material reliability, as well as significant progress. Assembly and space reduction, new results such as metal enclosures, prefabricated buildings, compact transformer substations and finally installed substations are also revolutionary. Due to society's increasing concern about the environment, the industry as a whole is rethinking the design and materials that may mean pollution, trying to replace them as much as possible with environmentally friendly communities. The inevitable development of society cannot and should not destroy the future of the earth. The time for sustainable development has come. So our work here today is a help in that sense. Manuscript profile

Open Access Article

17 - Optimal Power Allocation for Maximizing Secrecy Rate in Physical Layer Security Using Frequency Diverse Array Directional Modulation and Artificial Noise
Mahdi Tayyeb Massoud Hossein Khaleghi

The directional modulation is a prominent and practical technique for enhancing the physical layer security in modern communication systems. In this method, the message signal is modulated by an array of antennas and transmitted in a specific direction to the legitimate More

The directional modulation is a prominent and practical technique for enhancing the physical layer security in modern communication systems. In this method, the message signal is modulated by an array of antennas and transmitted in a specific direction to the legitimate receiver, such that in other directions, the signal is destroyed and not receivable by eavesdroppers. By incorporating random frequency diverse array directional modulation, secure communication can be achieved in both angular and distance dimensions for the legitimate receiver. However, when the eavesdropper is located near the legitimate receiver, the confidentiality performance of this solution significantly deteriorates. To address this issue, this paper proposes a novel approach that combines artificial noise with random frequency diverse array directional modulation and optimizes power allocation to attain the maximum secrecy rate. Simulation results demonstrate that our proposed approach improves the secrecy rate of the physical layer security by at least one bit per second per hertz compared to the method without artificial noise, and by at least two bits per second per hertz compared to the phased array directional modulation. Manuscript profile

Open Access Article

18 - Performance Improvement of High Voltage Transformer in Klystron Amplifier Power Supply by Magnetizing Current Balancing
Abolfazl Nasiri mohsen ganji seed mohamad Alavi

<p class="Abstract">In this research, the structure of a Full-bridge converter has been used to feed the klystron amplifier. Three Full-bridge transducer modules with high voltage transformers are used to supply the power of klystron (100 kW, 4 kV, 25 kV). The output of More

<p class="Abstract">In this research, the structure of a Full-bridge converter has been used to feed the klystron amplifier. Three Full-bridge transducer modules with high voltage transformers are used to supply the power of klystron (100 kW, 4 kV, 25 kV). The output of the transformers is rectifier in a star structure and after passing through a π filter, the circuit of the klystron lamp is supplied. The output of the power supply is 1 ms width and frequency of repetition is 50 Hz. The input voltage of the converter is 500 VDC, which is supplied by a three-phase feed. In this research, by balancing the magnetizing current of high frequency transformers, the maximum magnetization current of transformers decreases and decreases the maximum current of transistors. In addition, the core dimensions of the transformer decrease by reducing the maximum magnetization current. As a result, the dimensions, volume, and weight of the klystron drive circuit are reduced. Also, by using leakage inductance of high frequency transformer, series resonance circuit has been created and soft switching conditions have been provided. In this way, it improves the performance of the klystron driven circuit. Modulator performance has been simulated and approved using PSCAD software and resistive load.</p> Manuscript profile

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