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1
Romaniuk, F. A., V. Yu Rumiantsev, Yu V. Rumiantsev, and V. S. Kachenya. "Orthogonal Components Forming of the Microprocessor-Based Protection Input Signals." ENERGETIKA. Proceedings of CIS higher education institutions and power engineering associations 63, no. 4 (2020): 328–39. http://dx.doi.org/10.21122/1029-7448-2020-63-4-328-339.
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The use of orthogonal components (OS) is the main direction of determining information parameters in microprocessor relay protection and automation of electric power systems. Most of the measuring devices used in modern protection and automation devices can be implemented using known operating systems. Digital non-recursive frequency filters based on discrete Fourier transform are used for OS selection. The main disadvantage of these filters is their low performance that exceeds the period of industrial frequency. For the construction of high-speed measuring devices, this time of establishing the true output signal is often unacceptable. The article proposes to form the equivalent signal OS in microprocessor defenses based on the values of the cosine and sine axes of the main harmonic formed using a discrete Fourier transform, by multiplying them by a correction factor, which is a function of the values of the input signal amplitude and its main harmonic. The proposed algorithm for generating OS input signals in microprocessor defenses is characterized by high performance in transient modes and has wide functionality. A block diagram of an OS equivalent signal generator has been developed, all blocks of which can be implemented according to known schemes on a microelectronic and microprocessor element base. The OS shaper model is implemented in the MatLab-Simulink dynamic modeling environment. The model functioning was checked using two types of test actions, viz. a sinusoidal signal with a frequency of 50 Hz (idealized action) and a signal close to the real secondary current of a short-circuit current transformer. As a result of the performed calculations, a significant (up to two times) in the speed of the proposed method of OS formation in comparison with the formers based on the discrete Fourier transform, frequency properties of both formers being identical.
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Garcia-Guevara, Francisco M., Francisco J. Villalobos-Piña, Ricardo Alvarez-Salas, Eduardo Cabal-Yepez, and Mario A. Gonzalez-Garcia. "Stator Fault Detection in Induction Motors by Autoregressive Modeling." Mathematical Problems in Engineering 2016 (2016): 1–7. http://dx.doi.org/10.1155/2016/3409756.
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This study introduces a novel methodology for early detection of stator short circuit faults in induction motors by using autoregressive (AR) model. The proposed algorithm is based on instantaneous space phasor (ISP) module of stator currents, which are mapped toα-βstator-fixed reference frame; then, the module is obtained, and the coefficients of the AR model for such module are estimated and evaluated by order selection criterion, which is used as fault signature. For comparative purposes, a spectral analysis of the ISP module by Discrete Fourier Transform (DFT) is performed; a comparison of both methodologies is obtained. To demonstrate the suitability of the proposed methodology for detecting and quantifying incipient short circuit stator faults, an induction motor was altered to induce different-degree fault scenarios during experimentation.
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Bellan, Diego. "Circuit Modeling and Statistical Analysis of Differential-to-Common-Mode Noise Conversion Due to Filter Unbalancing in Three-Phase Motor Drive Systems." Electronics 9, no. 10 (2020): 1612. http://dx.doi.org/10.3390/electronics9101612.
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This work deals with circuit modeling of noise mode conversion due to system asymmetry in a three-phase motor drive system. In fact, it is well-known that in case of system asymmetry (e.g., slightly asymmetrical LC filter parameters), differential-mode noise can convert into common-mode noise, resulting in increased level of conducted electromagnetic interference. This phenomenon has been observed with measurements and reported in previous works, but a clear and rigorous analytical description is still a challenging point. The main novelty proposed in the paper is a rigorous analytical description of differential-to-common-mode noise conversion based on the Clarke transformation and the eigenvalue analysis. In particular, the magnitude and the frequency location of the differential-mode resonances injected into the common-mode circuit are derived in closed form. Moreover, since system asymmetry is usually uncontrolled (e.g., component tolerance and parasitic elements), a statistical analysis is also presented by treating the parameters of the LC filter as random variables. Thus, a second contribution proposed in the paper is the analytical derivation in closed form of the probability density function, the mean value, and the standard deviation of the random frequency location of the resonance peaks injected into the common-mode circuit. The importance of the analytical results derived in the paper is two-fold. First, a deep theoretical understanding of the phenomenon in terms of circuit theory concepts is achieved. Second, the impact of differential-to-common-mode noise conversion is described in quantitative terms. Thus, the obtained analytical results can be used to predict or explain the noise conversion impact on the frequency-domain measurements of common-mode currents. Theoretical derivations are validated through a time-domain Simulink implementation of a three-phase motor drive system, and a frequency-domain analysis through the discrete Fourier transform.
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Syvokobylenko, V. F., and V. A. Lysenko. "APPLICATION OF WAVELET TRANSFORM FOR PHASE-TO-GROUND FAULT PROTECTION IN MEDIUM VOLTAGE ELECTRICAL NETWORKS." Tekhnichna Elektrodynamika 2021, no. 4 (2021): 55–62. http://dx.doi.org/10.15407/techned2021.04.055.
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For electrical networks with voltage of 6-35 kV with a compensated, isolated or resistor-grounded neutral, a phase-to-ground protection has been developed, in which, based on the results of the time-frequency wavelet transform of zero-sequence currents, voltages and their derivatives, using the obtained analytical expression, the total reactive power wavelet for different frequencies is determined. It is shown that at the initial moment of a phase-to-ground fault on the damaged feeder the power is always positive, and on the undamaged feeder it is negative, regardless of the operating mode of the neutral. Wavelet transform coefficients are found by convolution of discrete values of measured signals with sine-cosine signals of the Morlet mother function. The time-reversed sequence of these signals is obtained using a matrix for which the rules for its formation are stated. An excess of the zero phase sequence voltage amplitude of the set value is used as a starting protection element. With the help of a mathematical model of the network, studies of the behavior of protection in case of blind and arc phase-to-ground faults at various degrees of compensation of capacitive currents, at various voltage values at the moment of the short circuit have been carried out. In all modes, a reliable protection operation is obtained, the sensitivity of which is an order of magnitude higher than the protection based on Fourier transforms. Positive results of testing a protection sample implemented on a microprocessor-based element base at a laboratory stand are obtained. References 20, figures 7, tables 2.
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Tian, An-Hong, Cheng-Biao Fu, Yu-Chung Li, and Her-Terng Yau. "Intelligent Ball Bearing Fault Diagnosis Using Fractional Lorenz Chaos Extension Detection." Sensors 18, no. 9 (2018): 3069. http://dx.doi.org/10.3390/s18093069.
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In this study we used a non-autonomous Chua’s circuit, and the fractional Lorenz chaos system. This was combined with the Extension theory detection method to analyze the voltage signals. The bearing vibration signals, measured using an acceleration sensor, were introduced into the master and slave systems through a Chua’s circuit. In a chaotic system, minor differences can cause significant changes that generate dynamic errors. The matter-element model extension can be used to determine the bearing condition. Extension theory can be used to establish classical and sectional domains using the dynamic errors of the fault conditions. The results obtained were compared with those from discrete Fourier transform analysis, wavelet analysis and an integer order chaos system. The diagnostic rate of the fractional-order master and slave chaotic system could reach 100% if the fractional-order parameter adjustment was used. This study presents a very efficient and inexpensive method for monitoring the state of ball bearings.
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Zhu, Yong, Zhen Chong Wang, Chang Xin Nai, and Lu Dong. "Measurement System for Soil Complex Resistivity Based on LabVIEW." Applied Mechanics and Materials 192 (July 2012): 333–40. http://dx.doi.org/10.4028/www.scientific.net/amm.192.333.
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Complex resistivity of soil must be measured using low-frequency power supply to overcome the skin effect, but, because of using higher frequency, the existing conventional complex resistivity meter is not suitable for soil. To this end, with the discrete Fourier transform and spectrum analysis, a measurement system for soil complex resistivity based on LabVIEW virtual instrumentation development platform and PXI data acquisition card was designed and developed. The system can measure the complex resistivity of the soil under low frequency, track the fluctuations of supply frequency automatically using of software synchronization technology, and then automatic adjust the sampling rate to reduce measurement error. The measurements results of the Cole-Cole circuit model of complex resistivity show that the system has a high accuracy.
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Khoa, N. M., and D. D. Tung. "Modeling for Development of Simulation Tool: Impact of TCSC on Apparent Impedance Seen by Distance Relay." Engineering, Technology & Applied Science Research 8, no. 5 (2018): 3332–37. http://dx.doi.org/10.48084/etasr.2199.
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The impact of thyristor controlled series capacitor (TCSC) on distance protection relays in transmission lines is analyzed in this paper. Voltage and current data are measured and collected at the relay locations to calculate the apparent impedance seen by distance protection relays in the different operating modes of the TCSC connected to the line. Short-circuit faults which occur at different locations on the power transmission line are considered in order to locate the fault for the purpose of evaluating the impact of TCSC on the distance protection relay. Matlab/Simulink simulation software is used to model the power transmission line with two sources at the two ends. Voltage source, transmission line, TCSC, voltage and current measurement, and discrete Fourier transform (DFT) blocks are integrated into the model. Simulation results show the impact of TCSC on the distance protection relay and determine the apparent impedance and fault location in the line.
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Chen, Jian Hui. "An Improved EMD Method and its Application in Nonstationary Signals Analysis." Advanced Materials Research 429 (January 2012): 313–17. http://dx.doi.org/10.4028/www.scientific.net/amr.429.313.
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Empirical mode decomposition (EMD) method based on HHT has exhibited unique advantages such as adaptability and highly efficiency in many nonlinear, nonstationary signals processing applications. It breaks the uncertainty principle limit, but the traditional EMD still has its deficiencies. In this article, we construct a new wavelet which has excellent decomposing-frequency performance and energy concentration, and then an improved EMD method based on this wavelet is presented. Results of numerical simulation show the validity and efficiency of the method proposed in paper are better than traditional one. Furthermore, some foreseeable trends of time-frequency distribution technologies are described. The systems in reality, strictly speaking, tend to non-linear, so most practical signals are non-stationary random signals. Nonlinear, nonstationary signals analysis is a very significant and difficult problem in almost all technical fields such as automation, communication, aerospace- engineering, biomedicine, structural fault diagnosis and so on. Owed to the rapid development of large scale integrated circuit technology and artificial intelligence, the exploration of signal processing theories have got a sharply impetus. A series of new modern signal processing theories and methods have appeared to meet the need of time-frequency joint analysis of nonlinear, non-Gaussian and non-stationary signals, including discrete short-time Fourier transform, wavelet transform, Hilbert-Huang transform and so on. Time-frequency joint analysis can observe the evolution of the signal in the time domain and the frequency domain simultaneously, provide local time-frequency characteristics of the signal.
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Qu, Liu, Deng, et al. "Analysis and Adjustment of Positioning Error of PSD System for Mobile SOF-FTIR." Sensors 19, no. 23 (2019): 5081. http://dx.doi.org/10.3390/s19235081.
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A PSD-based solar spot position detection system is developed for solar tracking closed-loop control of mobile SOF-FTIR (Solar Occultation Flux method based on Fourier Transform Infrared spectrometer). The positioning error factors of PSD (position sensitive detector) are analyzed in detail. A voltage model for PSD signal conditioning circuit has been established to investigate the noise factors. The model shows that the positioning error is mainly related to PSD dark current and circuit gain. A static voltage deduction calibration method based on genetic algorithm is proposed to eliminate the effect of dark current. The gain ratio between channels is calculated based on the fitting curve slope of discrete position data of PSD center point with different light intensity for circuit gain calibration. The positioning accuracy and precision are greatly enhanced, especially when the light intensity is weak, compared with uncalibrated results. The positioning accuracy of center, middle and edge areas of PSD can reach 0.14%, 0.49%, and 1.09%, respectively, after correction in the range of light intensity voltage from 40 mV to 20 V. The corresponding standard deviations of each region are 0.005, 0.009, and 0.014, respectively. The adjustment methods proposed in this paper improve both measurement accuracy and detection limit. The results demonstrate that the calibrated PSD positioning accuracy can meet the requirements of SOF-FTIR for solar tracking.
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Torchio, Riccardo, Dimitri Voltolina, Paolo Bettini, Federico Moro, and Piergiorgio Alotto. "Marching On-In-Time Unstructured PEEC Method for Electrically Large Structures with Conductive, Dielectric, and Magnetic Media." Electronics 9, no. 2 (2020): 242. http://dx.doi.org/10.3390/electronics9020242.
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The Marching On-In-Time (MOT) unstructured Partial Element Equivalent Circuit (PEEC) method for time domain electromagnetic problems is presented. The method allows the transient analysis of electrically large electromagnetic devices consisting of conductive, dielectric, and magnetic media coupled with external lumped circuits. By re-formulating PEEC following the Coulombian interpretation of magnetization phenomena and by using electric and magnetic vector potentials, the proposed approach allows for a completely equivalent treatment of electric and magnetic media and inhomogeneous and anisotropic materials are accounted for as well. With respect to the recently proposed Marching On-In-Time PEEC approach, based on the standard (structured) discretization of PEEC, the method presented in this paper uses a different space and time MOT discretization, which allows for a reduction in the number of the unknowns. Analytical and industrial test cases consisting in electrically large devices are considered (e.g., the model of a Neutral Beam Injector adopted in thermonuclear fusion applications). Results obtained from the simulations show that the proposed method is accurate and yields good performances. Moreover, when rich harmonic content transient phenomena are considered, the unstructured MOT–PEEC method allows for a significant reduction of the memory and computation time when compared to techniques based on Inverse Discrete Fourier Transform applied to the frequency domain unstructured PEEC approach.
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Jose, Julia Tholath, and Adhir Baran Chattopadhyay. "Modeling of the magnetizing phenomena of doubly fed induction generator using neuro-fuzzy algorithm considering non-linearity." International Journal of Electrical and Computer Engineering (IJECE) 9, no. 1 (2019): 23. http://dx.doi.org/10.11591/ijece.v9i1.pp23-33.
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Doubly fed Induction Generators (DFIGs) are quite common in wind energy conversion systems because of their variable speed nature and the lower rating of converters. Magnetic flux saturation in the DFIG significantly affect its behavior during transient conditions such as voltage sag, sudden change in input power and short circuit. The effect of including saturation in the DFIG modeling is significant in determining the transient performance of the generator after a disturbance. To include magnetic saturation in DFIG model, an accurate representation of the magnetization characteristics is inevitable. This paper presents a qualitative modeling for magnetization characteristics of doubly fed induction generator using neuro-fuzzy systems. Neuro-fuzzy systems with one hidden layer of Gaussian nodes are capable of approximating continuous functions with arbitrary precision. The results obtained are compared with magnetization characteristics obtained using discrete fourier transform, polynomial and exponential curve fitting. The error analysis is also done to show the effectiveness of the neuro fuzzy modeling of magnetizing characteristics. By neuro-fuzzy algorithm, fast learning convergence is observed and great performance in accuracy is achieved.
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Lin, Chih-Hsuan, and Kuei-Ann Wen. "An Innovative Successive Approximation Register Analog-to-Digital Converter for a Nine-Axis Sensing System." Journal of Low Power Electronics and Applications 11, no. 1 (2021): 3. http://dx.doi.org/10.3390/jlpea11010003.
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With nine-axis sensing systems in 5G smartphones, mobile power consumption has become increasingly important, and ultra-low-power (ULP) sensor circuits can decrease power consumption to tens of microwatts. This paper presents an innovative successive approximation register analog-to-digital converter, which comprises fine (three most significant bits (MSBs) plus course conversion (11 least significant bits (LSBs)) capacitive digital-to-analog converters (CDACs), ULP, four-mode reconfigurable resolution (9, 10, 11, or 12 bits), an internally generated clock, meta-detection, the switching base midpoint voltage (Vm) (SW-B-M), bit control logic, multi-phase control logic, fine (three MSBs) plus course conversion (11 LSBs) switch control logic, phase control logic, and an input signal plus negative voltage (VI + NEG) voltage generator. Then, the mechanism of the discrete Fourier transform (DFT)-based calibration is applied. The scalable voltage technique was used, and the analog/digital voltage was Vanalog (1.5 V) and Vdigital (0.9 V) to meet the specifications of the nine-axis ULP sensing system. The CDACs can reconfigure four-mode resolutions, 9–12 bits, for use in nine-axis sensor applications. The corresponding dynamic signal-to-noise and distortion ratio performance was 50.78, 58.53, 62.42, and 66.51 dB. In the 12-bit mode, the power consumption of the ADC was approximately 2.7 μW, and the corresponding figure of merit (FoM) was approximately 30.5 fJ for each conversion step.
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Lin, Chih-Hsuan, and Kuei-Ann Wen. "An Innovative Successive Approximation Register Analog-to-Digital Converter for a Nine-Axis Sensing System." Journal of Low Power Electronics and Applications 11, no. 1 (2021): 3. http://dx.doi.org/10.3390/jlpea11010003.
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With nine-axis sensing systems in 5G smartphones, mobile power consumption has become increasingly important, and ultra-low-power (ULP) sensor circuits can decrease power consumption to tens of microwatts. This paper presents an innovative successive approximation register analog-to-digital converter, which comprises fine (three most significant bits (MSBs) plus course conversion (11 least significant bits (LSBs)) capacitive digital-to-analog converters (CDACs), ULP, four-mode reconfigurable resolution (9, 10, 11, or 12 bits), an internally generated clock, meta-detection, the switching base midpoint voltage (Vm) (SW-B-M), bit control logic, multi-phase control logic, fine (three MSBs) plus course conversion (11 LSBs) switch control logic, phase control logic, and an input signal plus negative voltage (VI + NEG) voltage generator. Then, the mechanism of the discrete Fourier transform (DFT)-based calibration is applied. The scalable voltage technique was used, and the analog/digital voltage was Vanalog (1.5 V) and Vdigital (0.9 V) to meet the specifications of the nine-axis ULP sensing system. The CDACs can reconfigure four-mode resolutions, 9–12 bits, for use in nine-axis sensor applications. The corresponding dynamic signal-to-noise and distortion ratio performance was 50.78, 58.53, 62.42, and 66.51 dB. In the 12-bit mode, the power consumption of the ADC was approximately 2.7 μW, and the corresponding figure of merit (FoM) was approximately 30.5 fJ for each conversion step.
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Romaniuk, F. A., Yu V. Rumiantsev, V. Yu Rumiantsev, and I. V. Novash. "Improvement of Algorithm for Formation of Orthogonal Components of Input Quantities in Microprocessor Protection." ENERGETIKA. Proceedings of CIS higher education institutions and power engineering associations 64, no. 2 (2021): 95–108. http://dx.doi.org/10.21122/1029-7448-2021-64-2-95-108.
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The use of orthogonal components (OC) underlies the construction of measuring elements of modern protection and automation devices. In most microprocessor-based protections, the orthogonal component of the input signal is extracted using a discrete Fourier transform (DFT). The DFT disadvantages are its low speed, which is more than one period of the fundamental frequency, as well as the sensitivity to the free aperiodic component, which creates significant conversion errors depending on the time constant of its decay. Such a settling time of the true output signal is often unacceptable for the design of high-speed measuring devices. The paper proposes to form the OC of the equivalent signal according to the values of the cosine and sine OC of the fundamental harmonic, formed using the DFT by multiplying them by the resulting correction factor. The developed algorithm for the formation of orthogonal components of input signals in microprocessor protections is characterized by high speed in transient modes and it has wide functionality. So, the proposed digital device for forming the orthogonal components of an equivalent signal, in comparison with digital filter based on the DFT, has an increased operating speed both in the mode of occurrence of a short circuit and during the decay of the monitored signal, while maintaining the same characteristics as in the DFT in other modes. A block diagram of the proposed digital device for forming the OC of an equivalent signal has been developed, all blocks of which can be implemented on a microelectronic and microprocessor element base. A digital model of the specified device has been developed in the dynamic modeling system MatLab-Simulink in accordance with the structural diagram. As a result of the calculations, a significant (up to two times) increase in the performance of the proposed digital device for forming the OC in transient modes has been established in comparison with the shapers based on the DFT.
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Ogihara, Akio, and Shojiro Yoneda. "A 64-points switched-capacitor discrete fourier transform circuit for high-speed inverse discrete fourier transform circuit." Electronics and Communications in Japan (Part III: Fundamental Electronic Science) 73, no. 11 (1990): 21–30. http://dx.doi.org/10.1002/ecjc.4430731103.
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Romaniuk, F. A., V. Yu Rumiantsev, I. A. Novash, and Yu V. Rumiantsev. "Technique of Performance Improvement of the Microprocessor-Based Protection Measuring Element." ENERGETIKA. Proceedings of CIS higher education institutions and power engineering associations 62, no. 5 (2019): 403–12. http://dx.doi.org/10.21122/1029-7448-2019-62-5-403-412.
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The technique is proposed to improve the performance of the measuring element of microprocessor-based protection and its implementation is considered at the software level. Two factors mainly influence on the performance of the measuring elements of microprocessorbased protection of electrical installations. The first one is associated with the appearance of aperiodic and harmonic components in the measured signals due to transients and nonlinearity of the electrical installation elements, and the second–with the inertia of information processing algorithms, in particular–with analog and digital filtering. This leads to the fact that the signal determining time at the output of the measuring element is delayed to unacceptable values that in some cases makes the high-speed protection of electrical equipment ineffective. To solve this problem, it is proposed to form the output signal of the measuring element in the form of special equivalent signals, which are a function of the pre-calculated correction factor and orthogonal components of the controlled signal. In the MatLab-Simulink dynamic modeling environment a mathematical model of the developed measuring element has been implemented, as well as a model of the elements of the power system. Checking the functioning of the model of the measuring element was carried out with the use of 2 types of test effects, viz. a sinusoidal signal with a frequency of 50 Hz (idealized effect), as well as a signal close to the real secondary current of the current transformer in case of short circuit. Computational experiments carried out in relation to the current measuring element using harmonic and close-to-real test effects made it possible to reveal a significant (up to 2 times) increase in the performance of the proposed measuring element as compared to existing ones based on the implementation of the discrete Fourier transform.
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Mustapha, Abdul Hadi Bin, R. Hamdan, F. H. Mohd Noh, et al. "Fault location identification of double circuit transmission line using discrete wavelet transform." Indonesian Journal of Electrical Engineering and Computer Science 15, no. 3 (2019): 1356. http://dx.doi.org/10.11591/ijeecs.v15.i3.pp1356-1365.
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<span lang="EN-GB">The importance of supplying undisturbed electricity keep increasing due to modernization and lifestyle. Any disturbance in the power system may lead to discontinuation and degradation in the power quality. Therefore, detecting fault, fault type and fault location is a major issue in power transmission system in order to ensure reliable power delivery system. This paper will compare two prominent methods to estimate the fault location of double circuit transmission line. Those methods are Discrete Wavelet Transform algorithm and Fast Fourier Transform algorithm. Simulations has been carried out in MATLAB/Simulink and a variety of fault has been imposed in order to analyse the capability and accuracy of the fault location detection algorithm. Results obtained portrayed that both algorithms provide good performance in estimating the fault location. However, the maximum percentage error produced by the Discrete Wavelet Transform is only 0.25%, 0.6% lower than maximum error produces by Fast Fourier Transform algorithm. As a conclusion, Discrete Wavelet Transform possesses better capability to estimate fault location as compared to Fast Fourier Transform algorithm.</span>
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Keefe, C. Dale, and Melvin B. Comisarow. "Exact Interpolation of Apodized, Magnitude-Mode Fourier Transform Spectra." Applied Spectroscopy 43, no. 4 (1989): 605–7. http://dx.doi.org/10.1366/0003702894202418.
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A procedure is developed for the exact interpolation of apodized, magnitude-mode Fourier transform (FT) spectra. The procedure gives the true center frequency, i.e., the location of the continuous peak, from just the largest three discrete intensities in the discrete magnitude spectrum. The procedure is applicable for the peaks in the apodized magnitude spectrum of a time signal of the form f( t) = cos( ωt) exp(– t/τ). There are no restrictions on the value of the damping ratio T/τ. The procedure is demonstrated for the sine-bell and Hanning windows and is generalizable to other windows which consist of a sum of constants and sine/cosine terms. This includes the majority of commonly used windows.
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Chow, Kim H., and Melvin B. Comisarow. "Magnitude-Lorentzian interpolation of discrete, absorption-mode Fourier transform spectra." Computers & Chemistry 13, no. 3 (1989): 291–96. http://dx.doi.org/10.1016/0097-8485(89)85014-4.
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Wang, Hong-Fu, Xin-Xin Jiang, Shou Zhang, and Kyu-Hwang Yeon. "Efficient quantum circuit for implementing discrete quantum Fourier transform in solid-state qubits." Journal of Physics B: Atomic, Molecular and Optical Physics 44, no. 11 (2011): 115502. http://dx.doi.org/10.1088/0953-4075/44/11/115502.
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S, Jerritta, M. Murugappan, Khairunizam Wan, and Sazali Yaacob. "Electrocardiogram-based emotion recognition system using empirical mode decomposition and discrete Fourier transform." Expert Systems 31, no. 2 (2013): 110–20. http://dx.doi.org/10.1111/exsy.12014.
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Wang, Hong-Fu, Xiao-Qiang Shao, Yong-Fang Zhao, Shou Zhang, and Kyu-Hwang Yeon. "Protocol and quantum circuit for implementing theN-bit discrete quantum Fourier transform in cavity QED." Journal of Physics B: Atomic, Molecular and Optical Physics 43, no. 6 (2010): 065503. http://dx.doi.org/10.1088/0953-4075/43/6/065503.
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Romaniuk, E. A., V. Yu Rumiantsev, Yu V. Rumiantsev, and A. A. Dziaruhina. "Reducing the Impact of the Frequency Change on the Formation of Orthogonal Components of the Relay Protection Input Signals." ENERGETIKA. Proceedings of CIS higher education institutions and power engineering associations 63, no. 1 (2020): 42–54. http://dx.doi.org/10.21122/1029-7448-2020-63-1-42-54.
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Digital filters made with the use of discrete Fourier Transform are applied in most microprocessor protections produced both in the home country and abroad. When the input signal frequency deviates from the value to which these filters are configured, a signal is generated at their output with oscillation amplitude that is proportional to the deviation of the signal frequency from the specified one. The article proposes an algorithm for compensating the oscillations of orthogonal components of the output signals of digital filters implemented on the basis of a discrete Fourier transform, when the input signal frequency deviates from the nominal one. A mathematical model of the proposed digital filter with an algorithm for compensating the oscillations of its orthogonal components, as well as a signal model for reproducing input effects, is implemented in the MatLab-Simulink dynamic modeling environment. The digital filter model is provided with two channels, viz. a current channel and a voltage channel, which makes it possible to simulate their operation in relation to protections that use one or two input values, for example, for current and remote protection. Verification of the functioning of the digital filter model with compensation for fluctuations in its output signal was carried out with the use of two types of test effects, viz. a sinusoidal signal with a frequency of 48–51 Hz (idealized effect), and the effects that are close to the real secondary signals of measuring current transformers and voltage transformers in case of short circuits accompanied by a decrease in frequency. The conducted computational experiments with deviation of frequency from the nominal one, revealed the presence of undamped oscillations at the output of standard digital Fourier filters and their almost complete absence in the proposed digital filters. This makes us possible to recommend digital filters based on a discrete Fourier transform supplemented by an algorithm for compensation of fluctuations in the amplitudes of the output signals for the use in microprocessor protection.
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Zhang, Xiaoqing, and Yongzheng Zhang. "Calculation of Lightning Transient Responses on Wind Turbine Towers." Mathematical Problems in Engineering 2013 (2013): 1–8. http://dx.doi.org/10.1155/2013/757656.
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An efficient method is proposed in this paper for calculating lightning transient responses on wind turbine towers. In the proposed method, the actual tower body is simplified as a multiconductor grid in the shape of cylinder. A set of formulas are given for evaluating the circuit parameters of the branches in the multiconductor grid. On the basis of the circuit parameters, the multiconductor grid is further converted into an equivalent circuit. The circuit equation is built in frequency-domain to take into account the effect of the frequency-dependent characteristic of the resistances and inductances on lightning transients. The lightning transient responses can be obtained by using the discrete Fourier transform with exponential sampling to take the inverse transform of the frequency-domain solution of the circuit equation. A numerical example has been given for examining the applicability of the proposed method.
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Takiguchi, Koichi, Tsutomu Kitoh, Atsushi Mori, Manabu Oguma, and Hiroshi Takahashi. "Optical orthogonal frequency division multiplexing demultiplexer using slab star coupler-based optical discrete Fourier transform circuit." Optics Letters 36, no. 7 (2011): 1140. http://dx.doi.org/10.1364/ol.36.001140.
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Ashtari Jafari, Mohammad. "Comparative Application of Time-Frequency Methods on Strong Motion Signals." Advances in Civil Engineering 2021 (July 31, 2021): 1–14. http://dx.doi.org/10.1155/2021/9933078.
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Real-world physical signals are commonly nonstationary, and their frequency details change with time and do not remain constant. Fourier transform that uses infinite sine/cosine waves as basis functions represents frequency constituents of signals but does not show the variations of the signal frequency contents over time. Multiresolution demonstration of the time-frequency domain may be achieved by the techniques that can support adjustable resolution in time and frequency. Earthquake strong motion signals are nonstationary and indicate time-varying frequency content due to the scattering from the source to the site. In this paper, we applied short-time Fourier transform, S-transform, continuous wavelet transform, fast discrete wavelet transform, synchrosqueezing transform, synchroextracting transform, continuous wavelet synchrosqueezing, filter bank synchrosqueezing, empirical mode decomposition, and Fourier decomposition methods on the near-source strong motion signals from the 7 May 2020 Mosha-Iran earthquake to study and compare the frequency content of this event estimated by these methods. According to the results that are examined by Renyi entropy and relative error, synchroextracting performed better in terms of energy concentration, and the Fourier decomposition method revealed the lowest difference between the original and reconstructed records.
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Yamaguchi, Tomiharu, and Akinori Ueno. "Capacitive-Coupling Impedance Spectroscopy Using a Non-Sinusoidal Oscillator and Discrete-Time Fourier Transform: An Introductory Study." Sensors 20, no. 21 (2020): 6392. http://dx.doi.org/10.3390/s20216392.
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In this study, we propose a new short-time impedance spectroscopy method with the following three features: (1) A frequency spectrum of complex impedance for the measured object can be obtained even when the measuring electrodes are capacitively coupled with the object and the precise capacitance of the coupling is unknown; (2) the spectrum can be obtained from only one cycle of the non-sinusoidal oscillation waveform without sweeping the oscillation frequency; and (3) a front-end measuring circuit can be built, simply and cheaply, without the need for a digital-to-analog (D-A) converter to synthesize elaborate waveforms comprising multiple frequencies. We built the measurement circuit using the proposed method and then measured the complex impedance spectra of 18 resistive elements connected in series with one of three respective capacitive couplings. With this method, each element’s resistance and each coupling’s capacitance were estimated independently and compared with their nominal values. When the coupling capacitance was set to 10 nF or 1.0 nF, estimated errors for the resistive elements in the range of 2.0–10.0 kΩ were less than 5%.
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Pham, Giao N., Anh N. Bui, Binh A. Nguyen, Tung V. Nguyen, and Hai T. Nguyen. "Fast IQ Amplitude Approximation Method for ASIC Digital System." International Journal of Emerging Technology and Advanced Engineering 11, no. 8 (2021): 19–22. http://dx.doi.org/10.46338/ijetae0821_03.
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In some modules of digital systems, such as Fast Fourier Transform (FFT), Discrete Fourier transform (DFT), IQ (in-phase and quadrature components) modulation/ demodulation, the outputs use the complex data formed , and the calculation of its magnitude value √ are required. In software digital signal processing platform, the multiplication and square root operations are executed by using its math library; however, in Application specific integrated circuit (ASIC) digital system design, the implementation of those operators via Coordinate Rotation Digital Computer (CORDIC) algorithm requires the numerous resources and delays. So, in this paper, we present a fast approximation method for above problem which takes a small delay but acceptable accuracy for AISC digital system design. Keywords—ASIC, Digital system design, FFT, DFT, Fast amplitude approximation, Max-Min approximation.
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Elíasson, Jónas. "Eddy Heat Conduction and Nonlinear Stability of a Darcy Lapwood System Analysed by the Finite Spectral Method." Journal of Applied Mathematics 2014 (2014): 1–10. http://dx.doi.org/10.1155/2014/695425.
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A finite Fourier transform is used to perform both linear and nonlinear stability analyses of a Darcy-Lapwood system of convective rolls. The method shows how many modes are unstable, the wave number instability band within each mode, the maximum growth rate (most critical) wave numbers on each mode, and the nonlinear growth rates for each amplitude as a function of the porous Rayleigh number. Single amplitude controls the nonlinear growth rates and thereby the physical flow rate and fluid velocity, on each mode. They are called the flak amplitudes. A discrete Fourier transform is used for numerical simulations and here frequency combinations appear that the traditional cut-off infinite transforms do not have. The discrete show a stationary solution in the weak instability phase, but when carried past 2 unstable modes they show fluctuating motion where all amplitudes except the flak may be zero on the average. This leads to a flak amplitude scaling process of the heat conduction, producing an eddy heat conduction coefficient where a Nu-RaLrelationship is found. It fits better to experiments than previously found solutions but is lower than experiments.
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Bruce, Lori Mann, Navaneethakrishnan Balraj, Yunlong Zhang, and Qingyong Yu. "Automated Accident Detection in Intersections via Digital Audio Signal Processing." Transportation Research Record: Journal of the Transportation Research Board 1840, no. 1 (2003): 186–92. http://dx.doi.org/10.3141/1840-21.
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A system for automated traffic accident detection in intersections was designed. The input to the system is a 3-s segment of audio signal. The system can be operated in two modes: the two-class and multiclass modes. The output of the two-class mode is a label of “crash” or “noncrash.” In the multiclass mode of operation, the system identifies crashes as well as several types of noncrash incidents, including normal traffic and construction sounds. The system is composed of three main signal processing stages: feature extraction, feature reduction, and classification. Five methods of feature extraction were investigated and compared; these are based on the discrete wavelet transform, fast Fourier transform, discrete cosine transform, real cepstral transform, and mel frequency cepstral transform. Statistical methods are used for feature optimization and classification. Three types of classifiers are investigated and compared; these are the nearest-mean, maximum-likelihood, and nearest-neighbor methods. The results of the study show that the optimum design uses wavelet-based features in combination with the maximum-likelihood classifier. The system is computationally inexpensive relative to the other methods investigated, and the system consistently results in accident detection accuracies of 95% to 100% when the audio signal has a signal-to-noise-ratio of at least 0 decibels.
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Xie, Jingsong, Wei Cheng, Yanyang Zi, and Mingquan Zhang. "Phase-based spectrum analysis method for identifying weak harmonics." Journal of Vibration and Control 24, no. 23 (2018): 5585–96. http://dx.doi.org/10.1177/1077546318760904.
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Fault characteristic frequency extraction is an important means for the fault diagnosis of rotating machineries. Traditional signal processing methods commonly use the amplitude information of signals to detect damages. However, when the amplitudes of characteristic frequencies are weak, the recognition effects of traditional methods may be unsatisfactory. Therefore, this paper proposes the phase-based enhanced phase waterfall plot (EPWP) method and frequency equal ratio line (FERL) method for identifying weak harmonics. Taking a cracked rotor as an example, the characteristic frequency detection performances of the EPWP and FERL methods are compared with that of the traditional signal processing methods namely fast Fourier transform, short-time Fourier transform, discrete wavelet transform, continuous wavelet transform, ensemble empirical mode decomposition, and Hilbert–Huang transform. Research results demonstrate that the effects of EPWP and FERL for the recognitions of weak harmonics which are contained in steady signals and transient signals are better than that of the traditional signal processing methods. The accurate identification of weak characteristic frequencies in the vibration signals can provide an important reference for damage detections and improve the diagnostic accuracy.
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Zhang, Jialiang. "Fault Diagnosis of Nonlinear Analog Circuit Based on Generalized Frequency Response Function and LSSVM Classifier Fusion." Mathematical Problems in Engineering 2020 (September 22, 2020): 1–11. http://dx.doi.org/10.1155/2020/8274570.
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For fault diagnosis of nonlinear analog circuit, a novel method based on generalized frequency response function (GFRF) and least square support vector machine (LSSVM) classifier fusion is presented. The sinusoidal signal is used as the input of analog circuit, and then, the generalized frequency response functions are estimated directly by the time-domain formulations. The discrete Fourier transform of measurement data is avoided. After obtaining the generalized frequency response functions, the amplitudes of the GFRFs are chosen as the fault feature parameters. A classifier fusion algorithm based on least square support vector machine (LSSVM) is used for fault identification. Two LSSVM multifault classifiers with different kernel functions are constructed as subclassifiers. Fault diagnosis experiments of resistor-capacitance (RC) circuit and Sallen Key filter are carried out, respectively. The results show that the estimated GFRFs of the circuit are accurate, and the fault diagnosis method can get high recognition rate.
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Verdun, Francis R., Carlo Giancaspro, and Alan G. Marshall. "Effects of Noise, Time-Domain Damping, Zero-Filling and the FFT Algorithm on the “Exact” Interpolation of Fast Fourier Transform Spectra." Applied Spectroscopy 42, no. 5 (1988): 715–21. http://dx.doi.org/10.1366/0003702884429094.
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A frequency-domain Lorentzian spectrum can be derived from the Fourier transform of a time-domain exponentially damped sinusoid of infinite duration. Remarkably, it has been shown that even when such a noiseless time-domain signal is truncated to zero amplitude after a finite observation period, one can determine the correct frequency of its corresponding magnitude-mode spectral peak maximum by fitting as few as three spectral data points to a magnitude-mode Lorentzian spectrum. In this paper, we show how the accuracy of such a procedure depends upon the ratio of time-domain acquisition period to exponential damping time constant, number of time-domain data points, computer word length, and number of time-domain zero-fillings. In particular, we show that extended zero-filling (e.g., a “zoom” transform) actually reduces the accuracy with which the spectral peak position can be determined. We also examine the effects of frequency-domain random noise and roundoff errors in the fast Fourier transformation (FFT) of time-domain data of limited discrete data word length (e.g., 20 bit/word at single and double precision). Our main conclusions are: (1) even in the presence of noise, a three-point fit of a magnitude-mode spectrum to a magnitude-mode Lorentzian line shape can offer an accurate estimate of peak position in Fourier transform spectroscopy; (2) the results can be more accurate (by a factor of up to 10) when the FFT processor operates with floating-point (preferably double-precision) rather than fixed-point arithmetic; and (3) FFT roundoff errors can be made negligible by use of sufficiently large (> 16 K) data sets.
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Zhou, Chunjie, Yufeng Shi, Shuang-Hua Yang, Quan Yin, and Yuanqing Qin. "Characteristic Model-Based Adaptive Discrete-Time Sliding Mode Control for the Swing Arm in a Fourier Transform Spectrometer." IEEE Transactions on Systems, Man, and Cybernetics, Part C (Applications and Reviews) 42, no. 6 (2012): 1633–43. http://dx.doi.org/10.1109/tsmcc.2012.2212275.
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Aitzaz, Abbasi, Junsub Kim, Taehee Kim, Ki Park, and Sungbo Cho. "Electrical Characterization of Pork Tissue Measured by a Monopolar Injection Needle and Discrete Fourier Transform based Impedance Measurement." Applied Sciences 9, no. 19 (2019): 4049. http://dx.doi.org/10.3390/app9194049.
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Ultrasonography or fluoroscopy-guided needle injection has been used for intra-articular injection therapy against adhesive capsulitis and joint diseases. To improve the image-guided intra-articular injection therapy, electrical impedance measurement based positioning of the needle tip in the target tissue can be applied. The feasibility of the discrimination for the tissue layer at which the disposable monopolar injection needle tip position was investigated using the discrete Fourier transform (DFT)-based impedance measurement system and the ultrasound imaging device. The electrical impedance spectra of the pork tissue measured in the frequency range of 200 Hz to 50 kHz were characterized by designed equivalent circuit modeling analysis. The normalized impedance data of the tissue layers (dermis, hypodermis, and muscle) were significantly different from each other (p-value < 0.001). The DFT-based impedance measurement system with a monopolar injection needle can be complementary to the image-guided intra-articular injection therapy.
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Huang, Zanwu, Clive Roberts, Lei Chen, Shaobin Li, and Hongguang Wang. "A solution to transient failures of HVI track circuits caused by inrush interference based on wavelet analysis." Proceedings of the Institution of Mechanical Engineers, Part F: Journal of Rail and Rapid Transit 231, no. 3 (2016): 359–69. http://dx.doi.org/10.1177/0954409716630340.
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A track circuit never reporting block failure means a track section is reported as vacant to a railway control system, even if it is occupied by a train. This is a wrong side failure which may cause an accident. A high-voltage impulse (HVI) track circuit based on the fast Fourier transform is currently in use in China to solve this problem, but it has been observed that when used in electric railway systems large inrush currents can lead to another track circuit failure mode, which is referred to as a transient reporting block (TRB) in this paper. The root causes and impact of TRB track circuit failures are analyzed and a solution to the TRB failure mode based on wavelet analysis is proposed. Computer simulations and onsite experiments are carried out and the results show that the proposed approach can accurately extract the feature frequency and then effectively avoid the TRB failure, even if the HVI track signal is disturbed by a significant inrush of traction-return current.
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WANG, CHUN-CHING, YIH-CHUAN LIN, and CHI-YIN LIN. "ROM REDUCTION FOR OFDM SYSTEM USING TIME-STEALING STRATEGY." Journal of Circuits, Systems and Computers 15, no. 06 (2006): 907–21. http://dx.doi.org/10.1142/s0218126606003398.
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Modern communication systems frequently exploit the OFDM (Orthogonal Frequency Division Multiplex) technique to obtain a highly robust transmission of multimedia information, such as digital audio/video broadcast. OFDM and most of the other multimedia compression techniques usually require expensive computations, e.g., FFT (Fast Fourier Transform) and IMDCT (Inverse Modified Discrete Cosine Transform) processing. Traditionally, designing FFT and IMDCT separately involves a significant amount of redundancy in hardware. To reduce the required hardware, this investigation proposes a new ROM-sharing design for storing both FFT twiddle factors and IMDCT coefficients in a DAB (Digital Audio Broadcasting) receiver. We first analyze the correlation between FFT operations and IMDCT operations, and then the combinational logic circuit in the FFT processor is modified such that both IMDCT coefficients and FFT twiddle factors can be obtained simultaneously from a shared ROM. This design can also be applied for computing IFFT (Inverse Fast Fourier Transform) and MDCT for DAB transmitter. Compared with the traditional design using separate module scheme, our design does not need extra ROM for IMDCT/MDCT modules. Therefore, the new scheme offers superior solution for combining high-performance FFT (IFFT) operation and IMDCT (MDCT) operation.
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KLAPPENECKER, ANDREAS, and MARTIN RÖTTELER. "QUANTUM SOFTWARE REUSABILITY." International Journal of Foundations of Computer Science 14, no. 05 (2003): 777–96. http://dx.doi.org/10.1142/s0129054103002023.
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The design of efficient quantum circuits is an important issue in quantum computing. It is in general a formidable task to find a highly optimized quantum circuit for a given unitary matrix. We propose a quantum circuit design method that has the following unique feature: It allows to construct efficient quantum circuits in a systematic way by reusing and combining a set of highly optimized quantum circuits. Specifically, the method realizes a quantum circuit for a given unitary matrix by implementing a linear combination of representing matrices of a group, which have known fast quantum circuits. We motivate and illustrate this method by deriving extremely efficient quantum circuits for the discrete Hartley transform and for the fractional Fourier transforms. The sound mathematical basis of this design method allows to give meaningful and natural interpretations of the resulting circuits. We demonstrate this aspect by giving a natural interpretation of known teleportation circuits.
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Turski, Jacek. "Robotic Vision with the Conformal Camera: Modeling Perisaccadic Perception." Journal of Robotics 2010 (2010): 1–16. http://dx.doi.org/10.1155/2010/130285.
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Humans make about 3 saccades per second at the eyeball's speed of 700 deg/sec to reposition the high-acuity fovea on the targets of interest to build up understanding of a scene. The brain's visuosaccadic circuitry uses the oculomotor command of each impending saccade to shift receptive fields (RFs) to cortical locations before the eyes take them there, giving a continuous and stable view of the world. We have developed a model for image representation based on projective Fourier transform (PFT) intended for robotic vision, which may efficiently process visual information during the motion of a camera with silicon retina that resembles saccadic eye movements. Here, the related neuroscience background is presented, effectiveness of the conformal camera's non-Euclidean geometry in intermediate-level vision is discussed, and the algorithmic steps in modeling perisaccadic perception with PFT are proposed. Our modeling utilizes basic properties of PFT. First, PFT is computable by FFT in complex logarithmic coordinates that also approximate the retinotopy. Second, the shift of RFs in retinotopic (logarithmic) coordinates is modeled by the shift property of discrete Fourier transform. The perisaccadic mislocalization observed by human subjects in laboratory experiments is the consequence of the fact that RFs' shifts are in logarithmic coordinates.
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Maanani, Yacine, and Arezki Menacer. "Modeling and Diagnosis of the Inter-Turn Short Circuit Fault for the Sensorless Input-Output Linearization Control of the PMSM." Periodica Polytechnica Electrical Engineering and Computer Science 63, no. 3 (2019): 159–68. http://dx.doi.org/10.3311/ppee.13658.
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The purpose of this paper is the inter-turn short circuit fault Modeling and detection for the sensorless input-output linearization control of the permanent magnet synchronous motor (PMSM) based on the Extended Kalman Filter observer (EKF). The fault detection procedures are based through the estimation of the stator resistance variation by the Extended Kalman Filter observer and the Fast Fourier Transformer (FFT) for the stationary state, and the Discrete Wavelet Transform (DWT) analysis of the electrical characteristics of the PMSM, for the non-stationary state. However, the FFT spectral analysis and the DWT is a useful solution to ensure that the variation of the stator resistance estimation is caused by the inter-turn short circuit fault. The effectiveness of the sensorless control and the fault detection techniques are presented in a simulation in MATLAB/Simulink environment.
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Lounici, Mer Wan, and Xiao Ming Luan. "Implementation of Unitary Music Algorithm Using Xilinx System Generator." Advanced Materials Research 748 (August 2013): 629–33. http://dx.doi.org/10.4028/www.scientific.net/amr.748.629.
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The MUltiple SIgnal Classification MUSIC algorithm is a kind of DOA (Direction Of Arrival) estimation technique based on eigenvalue decomposition, which is also called subspace-based method [5]. In addition of its super resolution capability, MUSIC is very suitable for integration on logic circuit devices such as FPGAs (Field Programmable Gate Array).this paper proposes an implementation of unitary MUSIC algorithm using Xilinx System Generator (XSG). The design proposed uses CORDIC (COordinate Rotation DIgital Computer) -based Triangular Systolic Array for QR- decomposition to deal with EVD (eigenvalue decomposition). The MUSIC spectrum is computed with spatial DFT (Discrete Fourier Transform) using FFT block offered by Simulink- Xilinx blockset library. The performance of eight elements antenna array system was obtained and discussed.
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Verdun, Francis R., Tom L. Ricca, and Alan G. Marshall. "Beating the Nyquist Limit by Means of Interleaved Alternated Delay Sampling: Extension of Lower Mass Limit in Direct-Mode Fourier Transform Ion Cyclotron Resonance Mass Spectrometry." Applied Spectroscopy 42, no. 2 (1988): 199–203. http://dx.doi.org/10.1366/0003702884428149.
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According to the Nyquist theorem, the highest signal frequency which can be represented without foldover (aliasing) in a Fourier transform frequency-domain discrete spectrum is one-half of the time-domain sampling frequency. For example, since ion cyclotron resonance (ICR) frequency is inversely related to ionic mass-to-charge ratio, m/z, the highest ICR frequency (corresponding to the lowest correctly represented m/z) in direct-mode Fourier transform ICR mass spectrometry is restricted to one-half of the maximum sampling frequency, or about m/z ≥ 18 at 3.058 tesla (T) for a maximum sampling frequency of about 5.2 MHz. In this paper, we show that interleaved addition of two digitized time-domain transient signals, one of which is delayed by one-half of one sampling period (i.e., half of one cycle of the time-domain sampling frequency) with respect to the other, generates a time-domain discrete waveform which is indistinguishable from a single waveform produced by sampling at twice the original sampling rate. Thus, provided that the two transients have (or have been normalized to) the same magnitude, one can double the Nyquist-limited frequency range. If the sampling period is divided into three or more equal parts, with interleaved addition of three or more correspondingly delayed transients, the same method can further increase the upper frequency limit. The method is applied to the experimental doubling or quadrupling of FT/ICR direct-mode frequency range, as for example in the extension of the lower mass limit to below m/z = 12 at 3.058 T with a sampling rate of only 4.0 MHz.
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Perrott, Alison, Ludovic Caro, Mohamad Dernaika, and Frank Peters. "A Comparison between off and On-Chip Injection Locking in a Photonic Integrated Circuit." Photonics 6, no. 4 (2019): 103. http://dx.doi.org/10.3390/photonics6040103.
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The mutual and injection locking characteristics of two integrated lasers are compared, both on and off-chip. In this study, two integrated single facet slotted Fabry–Pérot lasers are utilised to develop the measurement technique used to examine the different operational regimes arising from optically locking a semiconductor diode laser. The technique employed used an optical spectrum analyser (OSA), an electrical spectrum analyser (ESA) and a high speed oscilloscope (HSO). The wavelengths of the lasers are measured on the OSA and the selected optical mode for locking is identified. The region of injection locking and various other regions of dynamical behaviour between the lasers are observed on the ESA. The time trace information of the system is obtained from the HSO and performing the FFT (Fast Fourier Transform) of the time traces returns the power spectra. Using these tools, the similarities and differences between off-chip injection locking with an isolator, and on-chip mutual locking are examined.
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He, Xiao Qi, Jun De Wang, Jun Hua Zhu, Xun Ping Li, and Jun Fu Liu. "Fatigue Life Prediction and Verification for HIC Hermetical Sealing under Random Vibration Loading." Applied Mechanics and Materials 668-669 (October 2014): 176–80. http://dx.doi.org/10.4028/www.scientific.net/amm.668-669.176.
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This work aims to predict fatigue life of hybrid integrated circuit (HIC) hermetical metal sealing structure mounted on PCB under random vibration loading. The prediction method consists of following steps. Firstly, finite-element model was developed to obtain model parameters (including natural frequencies and mode shapes) and power spectral density (PSD) of the critical part of sealing structure by ANSYS workbench. Secondly, modal test and random vibration test were conducted to verify the results of simulation. Thirdly, the Von Mises stress PSD was transformed into time-history data through inverse Fourier transform with Matlab program after calculating from the FEA results. The rainflow-counting algorithm was employed to evaluate cumulative damages of the critical part. The material’s S-N curve, Palmgren-Miner’s damage accumulation rule and rainflow-counting algorithm were used to predict fatigue life. A specially designed fixture and board with heat sink were used in the experiment to verify the first five mode shapes and response spectrum of the six critical points with hammer excitation. The calculation result of in this study is 70.3 hours which could be a reference for structural design of hybrid integrated circuit hermetical metal sealing under vibration conditions.
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Pelletier, J. D., and J. P. Field. "Predicting the roughness length of turbulent flows over landscapes with multi-scale microtopography." Earth Surface Dynamics Discussions 3, no. 4 (2015): 1107–42. http://dx.doi.org/10.5194/esurfd-3-1107-2015.
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Abstract. The fully rough form of the law of the wall is commonly used to quantify velocity profiles and associated bed shear stresses in fluvial, aeolian, and coastal environments. A key parameter in this law is the roughness length, z0. Here we propose a predictive formula for z0 that uses the amplitude and slope of each wavelength of microtopography within a discrete-Fourier-transform-based approach. Computational fluid dynamics (CFD) modeling is used to quantify the effective z0 value of sinusoidal microtopography as a function of the amplitude and slope. The effective z0 value of landscapes with multi-scale roughness is then given by the sum of contributions from each Fourier mode of the microtopography. Predictions of the equation are tested against z0 values measured in ~105 wind velocity profiles from southwestern US playa surfaces. Our equation is capable of predicting z0 values to 50 % accuracy, on average, across a four order-of-magnitude range.
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DAI, DONG, CHI K. TSE, BO ZHANG, and XIKUI MA. "HOPF BIFURCATION AS AN INTERMEDIATE-SCALE INSTABILITY IN SINGLE-STAGE POWER-FACTOR-CORRECTION POWER SUPPLIES: ANALYSIS, SIMULATIONS AND EXPERIMENTAL VERIFICATION." International Journal of Bifurcation and Chaos 18, no. 07 (2008): 2095–109. http://dx.doi.org/10.1142/s0218127408021592.
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This paper reports intermediate-scale instability in a single-stage power-factor-correction (PFC) power supply that employs a cascade configuration of a boost stage operating in discontinuous conduction mode (DCM) and a forward stage operating in continuous conduction mode (CCM). The two stages combine into a single stage by sharing one main switch and one control loop to achieve input PFC and tight output regulation. The main results are given by "exact" cycle-by-cycle circuit simulations. The effect of the intermediate-scale instability on the attainable power factor is illustrated in terms of total harmonic distortion (THD) which is found by taking the Fast Fourier Transform (FFT) of the input current. The intermediate-scale instability usually manifests itself as local oscillations within a line cycle. Based on the stability analysis of a buck converter operating in CCM, the underlying mechanism of such instability can be attributed to the Hopf bifurcation that occurred in CCM forward stage. Finally, experimental results are presented for verification purposes.
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Suvarna, S., K. Rajesh, and T. Radhu. "A Modified Architecture for Radix-4 Booth Multiplier with Adaptive Hold Logic." International Journal of Students' Research in Technology & Management 4, no. 1 (2016): 01–05. http://dx.doi.org/10.18510/ijsrtm.2016.411.
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High speed digital multipliers are most efficiently used in many applications such as Fourier transform, discrete cosine transforms, and digital filtering. The throughput of the multipliers is based on speed of the multiplier, and then the entire performance of the circuit depends on it. The pMOS transistor in negative bias cause negative bias temperature instability (NBTI), which increases the threshold voltage of the transistor and reduces the multiplier speed. Similarly, the nMOS transistor in positive bias cause positive bias temperature instability (PBTI).These effects reduce the transistor speed and the system may fail due to timing violations. So here a new multiplier was designed with novel adaptive hold logic (AHL) using Radix-4 Modified Booth Multiplier. By using Radix-4 Modified Booth Encoding (MBE), we can reduce the number of partial products by half. Modified booth multiplier helps to provide higher throughput with low power consumption. This can adjust the AHL circuit to reduce the performance degradation. The expected result will be reduce threshold voltage, increase throughput and speed and also reduce power. This modified multiplier design is coded by Verilog and simulated using Xilinx ISE 12.1 and implemented in Spartan 3E FPGA kit.
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Yan, Hong-Yan, and Jin Kwon Hwang. "Mode identification method of low-frequency oscillation for power system based on ambient data." COMPEL - The international journal for computation and mathematics in electrical and electronic engineering 40, no. 3 (2021): 441–55. http://dx.doi.org/10.1108/compel-10-2020-0337.
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Purpose The purpose of this paper is to improve the online monitoring level of low-frequency oscillation in the power system. A modal identification method of discrete Fourier transform (DFT) curve fitting based on ambient data is proposed in this study. Design/methodology/approach An autoregressive moving average mathematical model of ambient data was established, parameters of low-frequency oscillation were designed and parameters of low-frequency oscillation were estimated via DFT curve fitting. The variational modal decomposition method is used to filter direct current components in ambient data signals to improve the accuracy of identification. Simulation phasor measurement unit data and measured data of the power grid proved the correctness of this method. Findings Compared with the modified extended Yule-Walker method, the proposed approach demonstrates the advantages of fast calculation speed and high accuracy. Originality/value Modal identification method of low-frequency oscillation based on ambient data demonstrated high precision and short running time for small interference patterns. This study provides a new research idea for low-frequency oscillation analysis and early warning of power systems.
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Pelletier, Jon D., and Jason P. Field. "Predicting the roughness length of turbulent flows over landscapes with multi-scale microtopography." Earth Surface Dynamics 4, no. 2 (2016): 391–405. http://dx.doi.org/10.5194/esurf-4-391-2016.
Full textAbstract:
Abstract. The fully rough form of the law of the wall is commonly used to quantify velocity profiles and associated bed shear stresses in fluvial, aeolian, and coastal environments. A key parameter in this law is the roughness length, z0. Here we propose a predictive formula for z0 that uses the amplitude and slope of each wavelength of microtopography within a discrete-Fourier-transform-based approach. Computational fluid dynamics (CFD) modeling is used to quantify the effective z0 value of sinusoidal microtopography as a function of the amplitude and slope. The effective z0 value of landscapes with multi-scale roughness is then given by the sum of contributions from each Fourier mode of the microtopography. Predictions of the equation are tested against z0 values measured in ∼ 105 wind-velocity profiles from southwestern US playa surfaces. Our equation is capable of predicting z0 values to 50 % accuracy, on average, across a 4 order of magnitude range. We also use our results to provide an alternative formula that, while somewhat less accurate than the one obtained from a full multi-scale analysis, has an advantage of being simpler and easier to apply.
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Suprajitno, M., and S. A. Greenhalgh. "Theoretical vertical seismic profiling seismograms." GEOPHYSICS 51, no. 6 (1986): 1252–65. http://dx.doi.org/10.1190/1.1442178.
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Offset vertical seismic profiling (VSP) theoretical seismograms which include multiples and mode conversions can be computed using a modified “reflectivity” method. In this method, the transformed displacement potentials are first calculated by multiplying the source spectrum by the composite reflectivity function. Integration over wavenumber, followed by inverse Fourier transformation over the frequency range of the signal, yields the synthetic trace. The composite reflectivity function for a buried receiver is derived from Kennett’s matrices (Kennett, 1974, 1979) which are synthesized to form phase‐related reflection and transmission coefficients from a layer stack. Both conventional fixed source‐moving receiver and fixed receiver‐walkaway source (multioffset) VSP geometries can be handled easily. The method can also readily accommodate deviated‐hole VSP. The method is general in that no ray needs to be specified. Because the order of the multiples can be controlled, wraparound problems with the discrete Fourier transform can be avoided. The normal‐incidence VSP seismograms can be rapidly generated as a special case. Several examples illustrate the method. Some classes of laterally varying structures can be approximately handled by restricting the range of ray‐angle integration and by using the principle of superposition.