Artykuły w czasopismach: „Transient Signal Analysis”

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Fan, Wei, Z. K. Zhu, Wei Guo Huang i Gai Gai Cai. "Sparse Representation De-Noising Based on Morlet Wavelet Basis and its Application for Transient Feature Extraction". Applied Mechanics and Materials 526 (luty 2014): 200–204. http://dx.doi.org/10.4028/www.scientific.net/amm.526.200.

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Signals with multiple transients are often encountered with much noise in engineering. The transient feature extraction has always been the key issue for signal analysis. A new signal de-noising method combining sparse representation and Morlet wavelet basis is proposed for signal de-noising and feature extraction. Simulation study concerning multiple transients signal shows the effectiveness of this method in transient feature extraction. The efficiency of this de-noising method is also verified by its application to extract fault signature for gearbox.

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Guillén, Daniel, Gina Idárraga-Ospina i Camilo Cortes. "A New Adaptive Mother Wavelet for Electromagnetic Transient Analysis". Journal of Electrical Engineering 67, nr 1 (1.01.2016): 48–55. http://dx.doi.org/10.1515/jee-2016-0007.

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Abstract Wavelet Transform (WT) is a powerful technique of signal processing, its applications in power systems have been increasing to evaluate power system conditions, such as faults, switching transients, power quality issues, among others. Electromagnetic transients in power systems are due to changes in the network configuration, producing non-periodic signals, which have to be identified to avoid power outages in normal operation or transient conditions. In this paper a methodology to develop a new adaptive mother wavelet for electromagnetic transient analysis is proposed. Classification is carried out with an innovative technique based on adaptive wavelets, where filter bank coefficients will be adapted until a discriminant criterion is optimized. Then, its corresponding filter coefficients will be used to get the new mother wavelet, named wavelet ET, which allowed to identify and to distinguish the high frequency information produced by different electromagnetic transients.

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Alam, M. Shafiul, Md Shamimul Haque Chowdhury i Muhammad Athar Uddin. "Power System Switching Transient Detection using Wavelet Transformed Based Signal Decomposition". IIUC Studies 7 (19.10.2012): 241–48. http://dx.doi.org/10.3329/iiucs.v7i0.12270.

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Switching transient phenomena in Electric Power System develop several disturbances, sometimes very hazardous for the electrical equipment life, for the environment and for the human life. Switching transient phenomena produce over voltage, over current and electrical fields, which haven't to neglect. Several types of wavelet network algorithms have been considered for detection of power system switching transients. But both time and frequency information are accessible by multiresolution analysis (MRA). This paper presents a wavelet transform based multiresolution analysis of power system signal to detect, localize and extract switching transients. Power system switching transients have been simulated using MATLAB-7.01. The key idea underlying the approach is to decompose a distorted signal into other signals which represents a smoothed version and detailed version of the original signal. The decomposition is performed using multiresolution analysis. The proposed method appears to be robust for detection and localization of power quality disturbances produced due to load switching and capacitor switching. DOI: http://dx.doi.org/10.3329/iiucs.v7i0.12270 IIUC Studies Vol.7 2011: 241-248

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Wang, Li Di, Meng Wang i Chun Cheng Han. "Research on Simulation System for Power Transient Signal Analysis Based on Wavelet Theory". Advanced Materials Research 457-458 (styczeń 2012): 500–503. http://dx.doi.org/10.4028/www.scientific.net/amr.457-458.500.

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For the purpose of power system transient signal analysis, recognition and classification respectively ,this paper focuses on the study of electric power transient signal acquisition, signal preprocessing method and transient signal feature extraction .Based on the wavelet theory and some simulation experiments, the process of transient signal analysis is studied. And it makes a primary development of electric power transient signal analysis automatic simulation system by the simulation software. In this research, the wavelet denoising method is used and to extract the transient signal feature, which can be used in detecting transient occurrence time. Finally, the system for transient signal analysis is developed and has the wide application fields.

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Liu, Wei, i Tian Lan. "Analysis on the Characteristics of Transient Signal Transmission Based on GaAs Materials". Materials Science Forum 663-665 (listopad 2010): 502–5. http://dx.doi.org/10.4028/www.scientific.net/msf.663-665.502.

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The GaAs photoconductive switch is an important device in the measurement of the signal of ultra high-speed. In this paper, the transmission model of transient signals on GaAs photoconductive material is given, and the experimental system of near-field detection is set up. It is gotten that the full width half magnitude of signal is about 2ps. Based on the testing result of delay-time-modulation method, the relationship between signal amplitude and the form of connection mode is analyzed and discussed. It is shown that the coupling of capacity is important to acquire the transient signal.

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Hinich, M. J. "Detecting a transient signal by bispectral analysis". IEEE Transactions on Acoustics, Speech, and Signal Processing 38, nr 7 (lipiec 1990): 1277–83. http://dx.doi.org/10.1109/29.57556.

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NICHELATTI, MICHELE, PAOLO PETTAZZONI i GIOVANNI PALLOTTI. "SOME MATHEMATICAL TOOLS FOR THE ANALYSIS OF BIOLOGICAL SIGNALS". Journal of Mechanics in Medicine and Biology 07, nr 02 (czerwiec 2007): 215–27. http://dx.doi.org/10.1142/s0219519407002236.

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The paper presents an informal review of some techniques available for signal analysis. In the interpretation of biomedical signals, the individuation of hidden transient phenomena in the spectrum can have a crucial role for diagnostic purposes. Since most biological signals are nonstationary, the Fourier transform is not sufficient to detect possible transient phenomena in the spectrum; therefore, some improvements in the Fourier transform technique have been carried out by means of window functions in the transformation kernel. Some of the most important features of recent developments in signal analysis are discussed here, with special focus on the uncertainty principle governing any time–frequency analysis.

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Zhou, Qing, Xia Yang, Yong Jian Mao i Hong Jian Deng. "Wavelet Analysis of Transient Signals of Structural Responses to Impulsive Loads". Advanced Materials Research 452-453 (styczeń 2012): 1522–26. http://dx.doi.org/10.4028/www.scientific.net/amr.452-453.1522.

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Based on a brief introduction to elementary theory of wavelet analysis, the disadvantages of wavelet method and wavelet packet method are given. A new wavelet analysis procedure is proposed for decomposition and reconstruction of measured transient signals. This method can search by specific frequency paths, then overcomes the shortcomings of uniform frequency intervals in pure wavelet analyses and of large computational costs in common wavelet packet analyses. As examples, a signal-noise separation and a weak signal extraction are given to show the effectiveness of the new procedure.

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Prokhorov, D. A., A. Moraghan i J. Vink. "Search for gamma rays from SNe with a variable-size sliding-time-window analysis of the Fermi-LAT data". Monthly Notices of the Royal Astronomical Society 505, nr 1 (10.05.2021): 1413–21. http://dx.doi.org/10.1093/mnras/stab1313.

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ABSTRACT We present a systematic search for γ-ray emission from supernovae (SNe) in the Fermi Large Area Telescope (LAT) Pass 8 data. The sample of targets consists of 55,880 candidates from the Open Supernova Catalogue. We searched for γ rays from SNe by means of a variable-size sliding-time-window analysis. Our results confirm the presence of transient γ-ray emission from the sources of non-AGN classes, including transitional pulsars, solar flares, γ-ray bursts, novae, and the Crab Nebula, which are projected near some of these SN’s positions, and also strengthen support to the variable signal in the direction of SN iPTF14hls. The analysis is successful in finding both short (e.g. solar flares) and long (e.g. transitional pulsars) high flux states. Our search reveals two new γ-ray transient signals occurred in 2019 in the directions of optical transients that are SN candidates, AT2019bvr and AT2018iwp, with their flux increases within 6 months after the dates of SN’s discoveries. These signals are bright and their variability is at a higher statistical level than that of iPTF14hls. An exploration of archival multiwavelength observations towards their positions is necessary to establish their association with SNe or other classes of sources. Our analysis, in addition, shows a bright transient γ-ray signal at low Galactic latitudes in the direction of PSR J0205+6449. In addition, we report the results of an all-sky search for γ-ray transient sources. This provided two additional candidates to gamma-ray transient sources.

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Lai, Ying-Cheng, i Nong Ye. "Recent Developments in Chaotic Time Series Analysis". International Journal of Bifurcation and Chaos 13, nr 06 (czerwiec 2003): 1383–422. http://dx.doi.org/10.1142/s0218127403007308.

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In this paper, two issues are addressed: (1) the applicability of the delay-coordinate embedding method to transient chaotic time series analysis, and (2) the Hilbert transform methodology for chaotic signal processing.A common practice in chaotic time series analysis has been to reconstruct the phase space by utilizing the delay-coordinate embedding technique, and then to compute dynamical invariant quantities of interest such as unstable periodic orbits, the fractal dimension of the underlying chaotic set, and its Lyapunov spectrum. As a large body of literature exists on applying the technique to time series from chaotic attractors, a relatively unexplored issue is its applicability to dynamical systems that exhibit transient chaos. Our focus will be on the analysis of transient chaotic time series. We will argue and provide numerical support that the current delay-coordinate embedding techniques for extracting unstable periodic orbits, for estimating the fractal dimension, and for computing the Lyapunov exponents can be readily adapted to transient chaotic time series.A technique that is gaining an increasing attention is the Hilbert transform method for signal processing in nonlinear systems. The general goal of the Hilbert method is to assess the spectrum of the instantaneous frequency associated with the underlying dynamical process. To obtain physically meaningful results, it is necessary for the signal to possess a proper rotational structure in the complex plane of the analytic signal constructed by the original signal and its Hilbert transform. We will describe a recent decomposition procedure for this task and apply the technique to chaotic signals. We will also provide an example to demonstrate that the methodology can be useful for addressing some fundamental problems in chaotic dynamics.

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Lazzari, Eleonora Fripp, Adriano Peres de Morais, Maicon Ramos, Renato Ferraz, Tiago Marchesan, Vitor Cristiano Bender, Rodinei Carraro, Herber Fontoura, Cristian Correa i Mariana Resener. "A Comprehensive Review on Transient Recovery Voltage in Power Systems: Models, Standardizations and Analysis". Energies 16, nr 17 (1.09.2023): 6348. http://dx.doi.org/10.3390/en16176348.

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Electrical power systems are exposed to transient disturbances that change the voltage and current signals of the network, which can interrupt power and damage equipment. In high-frequency phenomena, it is essential to study the transient recovery voltage (TRV) to ensure the electrical insulation limits of circuit breakers are not violated, thus leading to a safe and reliable operation. Adequate models are crucial to achieving satisfactory results in the studies, according to the range of frequency of the transient being evaluated. This paper presents a comprehensive literature review of methods and models for studying electromagnetic transients, focusing on TRV requests imposed on circuit breakers, in addition to fault-clearing simulations on real system modeling. The analyses are fundamental both for the evaluation of the amplitude of the voltage signal and for its rate of rise. We also compare the reviewed models and techniques to provide a handy resource for researchers.

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Wang, Zhe Yuan, Li Jiang, Ming Hu Xu i Wei Gang Zheng. "Application of Wavelet Transform in Transient Signal". Applied Mechanics and Materials 556-562 (maj 2014): 4711–17. http://dx.doi.org/10.4028/www.scientific.net/amm.556-562.4711.

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In this paper, analog signals will be built upon the dynamic load of transient signal with the help of MATLAB simulation method and wavelet transform concept, and analyze it with the application of wavelet denoise method, whose good effects would be proved by simulation experiment. To dispel noise from noisy signal through wavelet resolution theory approach based on collection of simulation experiment and theory. In conclusion, wavelet kernel function and decomposition have direct effect to denoise. In this paper, we’ve made an analysis to electric power transient signal characteristics by combination of wavelet basic theory and simulation experiment

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Luo, Zhong Hui, i Qi Jun Xiao. "Time-Frequency Features of Signal Analysis and its Application in Mechanical Fault Diagnosis". Advanced Materials Research 834-836 (październik 2013): 1065–68. http://dx.doi.org/10.4028/www.scientific.net/amr.834-836.1065.

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The early fault detection of mechanical equipment is the technical support of automation equipment to run efficiently. Because of various faults have the characteristics of sudden, transient degeneration, so the traditional Fourier transform based on signal processing method can't meet the needs of the transient signal. This paper discusses time-frequency analysis technology of local wave from signal denoising, signal singularity detection and signal frequency band energy distribution analysis to extract the transient signal characteristics, and the motor bearing fault is put forward as an example, the effectiveness of the proposed method is verified.

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Li, H., H. Q. Zheng i L. W. Tang. "Hilbert-Huang Transform and Its Application in Gear Faults Diagnosis". Key Engineering Materials 291-292 (sierpień 2005): 655–60. http://dx.doi.org/10.4028/www.scientific.net/kem.291-292.655.

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Time-frequency and transient analysis have been widely used in signal processing and faults diagnosis. These methods represent important characteristics of a signal in both time and frequency domain. In this way, essential features of the signal can be viewed and analyzed in order to understand or model the faults characteristics. Historically, Fourier spectral analyses have provided a general approach for monitoring the global energy/frequency distribution. However, an assumption inherent to this method is the stationary and linear of the signal. As a result, Fourier methods are not generally an appropriate approach in the investigation of faults signals with transient components. This work presents the application of a new signal processing technique, empirical mode decomposition and the Hilbert spectrum, in analysis of vibration signals and gear faults diagnosis for a machine tool. The results show that this method may provide not only an increase in the spectral resolution but also reliability for the gear faults diagnosis.

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Wang, Y., J. Lin i G. H. Zhou. "Analysis of DC offset Influence on Transient Signal". Journal of Physics: Conference Series 48 (1.10.2006): 462–66. http://dx.doi.org/10.1088/1742-6596/48/1/088.

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Gao, Yuan Sheng, Qiang Chen, Qiang Sun, Zhong Chen i Wen Hai Zhang. "The Impedance Calculation Methods Using Damped Sinusoidal Signal". Advanced Materials Research 860-863 (grudzień 2013): 2003–6. http://dx.doi.org/10.4028/www.scientific.net/amr.860-863.2003.

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There are large number of transient signals will be produced when the operation mode is changed. And the frequency of the transient signals distributed in wide range. The most of them are damped and oscillated. The impedance is a popular feature in power system, and it has been widely used in relay protection and fault location. So the impedance calculation based on the damped sinusoidal signal have been the important way to diagnosis the fault, locate the fault and so on. But the methods used now are based on the fundamental impedance calculation theory, lacking theoretical basis. In fact, the traditional methods for fundamental signal calculation are not appropriate for the quantitative analysis of damped sinusoidal signal. The paper analyzed the impedance calculation based on damped sinusoidal signal, combined the features of damped sinusoidal signals and the traditional impedance calculation method. The two typical signal analysis methods for damped sinusoidal signal extraction are used to calculate the accurate impedance based on the different extraction results. And the analysis laid a foundation for the impedance calculation using damped sinusoidal signals.

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Gómez-Luna, Eduardo, Dixon E. Cuadros-Orta, John E. Candelo-Becerra i Juan C. Vasquez. "The Development of a Novel Transient Signal Analysis: A Wavelet Transform Approach". Computation 12, nr 9 (3.09.2024): 178. http://dx.doi.org/10.3390/computation12090178.

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This paper presents a new method for the analysis of transient signals in the frequency domain based on the Continuous Wavelet Transform (CWT). The proposed case study involves test signals measured from an electronic switch considering open and close operations. The source is connected to inductive, resistive, and capacitive loads. Resonance behaviors are introduced and compared with the Discrete Fourier Transform (DFT). Multiple factors, such as reliability, repeatability, high noise attenuation, and the smoothing of the analyzed spectrum, are considered in this study. This proposed study highlights the effectiveness of CWT in signal processing, especially in obtaining a detailed spectrum that reveals the behavior of electrical circuits. Resonance behaviors were analyzed, demonstrating that the signal processing performed by CWT is better for spectrum analysis than DFT. This study shows the potential of CWT to analyze transient electrical signals, specifically for identifying and characterizing the behavior of load connections and disconnections.

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Guers, Manton J. "Consistent physical frequencies in time-frequency analysis". Journal of the Acoustical Society of America 154, nr 4_supplement (1.10.2023): A209. http://dx.doi.org/10.1121/10.0023302.

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Wavelet transforms have been studied extensively for a wide variety of applications such as signal compression and signal denoising. Wavelet transforms have also been examined for the detection of transient signals. However, wavelet levels (and corresponding pseudo-frequencies) are inherently dependent on the sampling rate of the analyzed data. The work presented herein examines how wavelet analysis can produce inconsistent data representations for the same analytical signal digitized at different sampling rates. Results are compared to time-octave and other time-frequency representations to identify methodologies which produce consistent characterization of physical frequencies. Similarities and difference between approaches are discussed.

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IOINOVICI, ADRIAN, i SORIN COSTINER. "COMPUTER-AIDED ANALYSIS OF CYCLICALLY SWITCHING CIRCUITS WITH IMPLICIT CONTROLLED TRANSITION TIMES". Journal of Circuits, Systems and Computers 01, nr 04 (grudzień 1991): 373–99. http://dx.doi.org/10.1142/s0218126691000136.

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The power electronics circuits can be seen as a subset of periodically switched networks. Their distinctive feature is the variable duration of the switching stages, dependent on implicit, threshold conditions. The paper presents a new computer-oriented approach for transient and steady-state analysis of this class of electronic circuits. The switching elements are extracted in a linear time-variable two-port, which is defined by its nodal equations. A set of modified nodal equations is obtained for describing the overall transient of the circuit. No small-signal approximations are required. The analytical expressions of the network waveforms are found accurately for each switching stage. The transient computation is based on the cyclical use of these expressions together with the threshold conditions. The general method is then applied to simulation of current-mode quasi-resonant converters. Transients due to large-signal changes in the line voltage and load are studied. The influence of the load value on transient peaks is pointed out. The voltage conversion ratio versus switching frequency is studied for both the half- and full-wave mode operation. A computer program for time-domain simulation of power quasi-resonant converters is developed based on this approach.

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Mishra, Sanhita, Sarat Chandra Swain i Ritesh Dash. "Switching transient analysis for low voltage distribution cable". Open Engineering 12, nr 1 (1.01.2022): 29–37. http://dx.doi.org/10.1515/eng-2022-0004.

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Abstract Low voltage cable is primarily connected from the transmission system to several household applications. It is quite common that switching transient in the power system during the energization of the high voltage and low voltage cables have a very crippling effect on the cable as well as the power system components. Hence, an experiment has been performed in the laboratory with a low voltage cable-connected motor system. The experimental results have been validated in the simulation platform, and they are capable of predicting the transient behavior during power cable energization. The effect of transients on power cables during the energization of devices has been investigated in this study in the form of voltage, current, and frequency. Discrete wavelet transform is implemented for the decomposition of the transient current. The generated approximation signal is used to quantify the severity during switching transient condition.

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Wang, Wan Jin, i Kui Feng Chen. "Research of the Transient Signal Recognition Based on Empirical Mode Decomposition". Applied Mechanics and Materials 548-549 (kwiecień 2014): 1173–78. http://dx.doi.org/10.4028/www.scientific.net/amm.548-549.1173.

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This paper introduces the empirical mode decomposition (EMD) method of the basic theory, problems and means to solve. Apply the approach to mechanical vibration signal containing a transient pulse processing and analysis carried out, and the wavelet time-frequency analysis methods are compared, the results show that it can effectively decompose nonlinear and non-stationary vibration signals, and has a self-adaptive, and in the time domain and frequency domain have better resolution capabilities, and the component with a more clear physical meaning. Due to its diversity of showing the results, you can make further precise analysis of a single component, and the transient signals can be effectively recognized, and can locate mutation point in time, describing the time-frequency localization properties. EMD, transient signals, mechanical vibration

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Sharma, Aditya, i D. K. Palwalia. "Small Signal Modelling and Stability Analysis of a Grid Connected Inverted Based Microgrid". Indian Journal Of Science And Technology 17, nr 19 (14.05.2024): 2024–37. http://dx.doi.org/10.17485/ijst/v17i19.379.

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Objectives: This work focuses on the stability analysis of grid connected microgrids. It considers the impact of load disturbance and grid voltage change on voltage and current levels, as well as reactive and active power responses, is analysed. Methods: A comprehensive small-signal state-space model is developed for an inverter-based microgrid, incorporating submodules of inverters, phase-locked loops (PLLs), and LCL filters. The model is linearized around a stable operating point, and eigenvalue analysis is performed and validated through MATLAB/Simulink simulations. A current controller operating in the d-q frame is proposed to enhance stable power conversion and maintain microgrid stability. Findings: The proposed model and control strategy demonstrate the microgrid's ability to maintain transient voltage stability under severe dynamic conditions. During a 10% grid voltage fluctuation, the microgrid exhibits stable active and reactive power responses, with currents and voltages at the point of common coupling stabilizing within 0.2 seconds. Furthermore, when a 25 kVA active load is disconnected, the microgrid effectively manages the power transition, maintaining stable operation with minimal deviations in key parameters. The current controller simplifies AC current control, integrating active power management from solar input, DC-link voltage stability, and reactive power control. Novelty: The novelty lies in the comprehensive analysis of transient voltage stability in grid-connected microgrids under grid voltage fluctuations and load disturbances, areas that have received limited attention in previous research. By developing a detailed small-signal state-space model incorporating PLL and LCL filter dynamics and proposing a robust control strategy with the current controller, this study offers new insights into enhancing the resilience and reliability of grid-connected microgrids during transient events. Keywords: Microgrid, Small Signal Stability, Voltage Source Inverter, State Space model, Eigen Values

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Chen, Man, i Biao Ma. "Fault Diagnosis of Wet-Shift Clutch Based on STFT and Wavelet". Advanced Materials Research 301-303 (lipiec 2011): 1560–67. http://dx.doi.org/10.4028/www.scientific.net/amr.301-303.1560.

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The paper analyzes the failure mechanism of the wet shifting clutch, and puts forward the concept that the deformation of the clutch friction plate leads to the irregular collision between the driving and driven sides of disengaged clutch and accordingly forms the transient pulse signal; the short-time Fourier analysis on the vibration signals of failed clutch obtained via test proves such concept. The transient pulse signal in the relatively strong background signal is clearly extracted through the wavelet decomposition after zero setting, and an efficient wet shifting clutch fault diagnosis method is hereby formed.

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Zheng, Chen, Qionglin Li, Shuming Liu, Shuangyin Dai, Bo Zhang i Yajuan Liu. "Power Quality Transient Disturbance Diagnosis Based on Dynamic Large Convolution Kernel and Multi-Level Feature Fusion Network". Energies 17, nr 13 (1.07.2024): 3227. http://dx.doi.org/10.3390/en17133227.

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Power quality is an important metric for the normal operation of a power system, and the accurate identification of transient signals is of great significance for the improvement of power quality. The diverse types of power system transient signals and strong characteristic coupling brings new challenges to the analysis and identification of power system transient signals. In order to enhance the identification accuracy of transient signals, one method of power system transient signal identification is proposed based on a dynamic large convolution kernel and multilevel feature fusion network. First, the more fine-grained and more informative features of the transient signals are extracted by the dynamic large convolution kernel feature extraction module. Then, the multi-scale local features are adaptively fused by the multilevel feature fusion module. Finally, the fused features are reduced in dimension by the fully connected layer in the classification module and fed into the SoftMax layer for transient signal type detection. The proposed method can effectively improve the small receptive field problem of convolutional neural networks and the lack of ability of Transformer network in extracting local context information. Compared with five other power quality transient disturbance identification models, the experimental results show that the proposed method has better diagnostic accuracy and anti-noise capability.

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Plusquellic, J., A. Singh, C. Patel i A. Gattiker. "Power supply transient signal analysis for defect-oriented test". IEEE Transactions on Computer-Aided Design of Integrated Circuits and Systems 22, nr 3 (marzec 2003): 370–74. http://dx.doi.org/10.1109/tcad.2002.807896.

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Ishikawa, Toru, Young Kyu Kwon i Hiroshi Kuwano. "Fourier analysis for the isothermal capacitance transient spectroscopy signal". Applied Physics Letters 47, nr 10 (15.11.1985): 1097–99. http://dx.doi.org/10.1063/1.96341.

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Plusquellic, J. F., S. P. Levitan i D. M. Chiarulli. "Digital IC device testing by transient signal analysis (TSA)". Electronics Letters 31, nr 18 (31.08.1995): 1568–70. http://dx.doi.org/10.1049/el:19951065.

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Zhao, Bin, Guanghao Yu, Dong Wang, Lei Chen i Jingning Ou. "Analysis of Transient Response of ZPW-2000A Jointless Track Circuit Considering Frequency Variation". Computational Intelligence and Neuroscience 2022 (30.04.2022): 1–7. http://dx.doi.org/10.1155/2022/2257313.

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In order to accurately analyze the influence of electromagnetic transient signals on the jointless track circuit when the electromagnetic transient signal propagates in the rail, it is necessary to consider the frequency-variable load terminated in the ZPW-2000A jointless track circuit and the frequency-variable loss inside the rail. A method is proposed for calculating the transient response of transmission lines system with frequency-variable end load of jointless track circuit. Firstly, the transmission lines model of jointless track circuit is established, based on multiconductor transmission lines theory, the model equation is deduced and discretized by finite difference time domain (FDTD). The vector fitting method is used to express the admittance of the tuning region in the track circuit, and the rational approximation function of the tuning region is derived from the poles, residues, and constants. The voltage and current at nodes in the tuning region are calculated by piecewise linear recursive convolution algorithm. Combined with the discrete transmission line equation, the current and voltage expression of the transient electromagnetic signal at the receiving end of the track circuit in time domain is obtained. Compared with state variable method, the error is less than 6%, which verifies the correctness of the proposed method. Finally, this paper studies the influence laws of different factors on the overvoltage at the receiving end of jointless track circuit and the weak links of jointless track circuit under the influence of transient electromagnetic signal. It provides theoretical reference for fault research and anti-interference analysis of ZPW-2000A jointless track circuit.

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Semyonov, E. V. "Analysis of the Structure of Nonlinear Distortions at Baseband Pulse Impacts Using Behavioral Nonlinear Models of Electrical Circuits". Journal of the Russian Universities. Radioelectronics 25, nr 2 (27.04.2022): 29–39. http://dx.doi.org/10.32603/1993-8985-2022-25-2-29-39.

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Introduction. Measuring harmonic distortions of a baseband pulse signal constitutes a problem due to the continuous nature of their spectrum. In order to obtain nonlinear distortions of a signal, a comparison should be conducted either of the object’s responses to two different test signals or those of the real object and its linearized model. However, such an approach does not distinguish between various physical factors that cause nonlinear distortions. This, as a result, complicates the optimization of devices.Aim. To develop an approach capable of determining the contribution of various sources to the nonlinear distortion of baseband pulse signals.Materials and methods. The method under consideration involves a synthesis of a nonlinear behavioral model for an object and a comparison of the model’s output signals when linearizing some (or all) of the characteristic functions in this model. This allows distinguishing the contribution of inertialess, capacitive nonlinearity and nonlinearity associated with signal recirculation in feedbacks. An example of a three-stage baseband pulse amplifier (with step functions as test signals) is provided, for which a behavioral model was synthesized in the form of a second-order nonlinear recursive filter.Results. The aggregate signal of nonlinear distortions obtained using the presented method was found to be similar to that obtained by subtracting the responses to two different test signals. Further, the distortions caused by static amplitude nonlinearity, capacitive reactivity nonlinearity and energy recirculation between different reactive storages were distinguished. The nonlinearity of the amplitude characteristic exhibits its effect at the end of the transient process, the nonlinearity with the capacitive nature – at the beginning of the transient process, and the nonlinearity of energy recirculation – in the middle part of the transient process. It is shown that even parts of the nonlinear distortions at step impact, caused by individual physical nonlinearity factors, exceed the harmonic distortions of a RF-pulse signal.Conclusion. The considered method is particularly useful when designing wideband devices with feedbacks, since the nonlinearity of energy recirculation takes effect long after the visual end of the transient process.

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Semyonov, E. V. "Analysis of the Structure of Nonlinear Distortions at Baseband Pulse Impacts Using Behavioral Nonlinear Models of Electrical Circuits". Journal of the Russian Universities. Radioelectronics 25, nr 2 (27.04.2022): 29–39. http://dx.doi.org/10.32603/1993-8985-2022-25-2-29-39.

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Introduction. Measuring harmonic distortions of a baseband pulse signal constitutes a problem due to the continuous nature of their spectrum. In order to obtain nonlinear distortions of a signal, a comparison should be conducted either of the object’s responses to two different test signals or those of the real object and its linearized model. However, such an approach does not distinguish between various physical factors that cause nonlinear distortions. This, as a result, complicates the optimization of devices.Aim. To develop an approach capable of determining the contribution of various sources to the nonlinear distortion of baseband pulse signals.Materials and methods. The method under consideration involves a synthesis of a nonlinear behavioral model for an object and a comparison of the model’s output signals when linearizing some (or all) of the characteristic functions in this model. This allows distinguishing the contribution of inertialess, capacitive nonlinearity and nonlinearity associated with signal recirculation in feedbacks. An example of a three-stage baseband pulse amplifier (with step functions as test signals) is provided, for which a behavioral model was synthesized in the form of a second-order nonlinear recursive filter.Results. The aggregate signal of nonlinear distortions obtained using the presented method was found to be similar to that obtained by subtracting the responses to two different test signals. Further, the distortions caused by static amplitude nonlinearity, capacitive reactivity nonlinearity and energy recirculation between different reactive storages were distinguished. The nonlinearity of the amplitude characteristic exhibits its effect at the end of the transient process, the nonlinearity with the capacitive nature – at the beginning of the transient process, and the nonlinearity of energy recirculation – in the middle part of the transient process. It is shown that even parts of the nonlinear distortions at step impact, caused by individual physical nonlinearity factors, exceed the harmonic distortions of a RF-pulse signal.Conclusion. The considered method is particularly useful when designing wideband devices with feedbacks, since the nonlinearity of energy recirculation takes effect long after the visual end of the transient process.

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Streck, Luiza, Thomas Roth, Andreas Noel, Peter Keil i Andreas Jossen. "Analysis of Transient Current and Heat Flow during Voltage Holds: For Relaxed and Unrelaxed G/NMC811 Cells". Journal of The Electrochemical Society 171, nr 7 (1.07.2024): 070515. http://dx.doi.org/10.1149/1945-7111/ad5d1b.

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This study investigates the transient heat flow during voltage holds for multi-layer pouch G/NMC811 lithium-ion cells. When applying a voltage hold to estimate the amount of parasitic side reactions, there is first a transient phase followed by a steady state. According to the literature, reversible processes mainly influence the transient phase, while the steady state presents the side reaction current. This work investigates the contributions to the transient behavior, evaluating the thermal and electrical signals and deconvoluting the different parasitic side reactions. In addition, a comparison between relaxed and unrelaxed states is performed, analyzing different temperatures and voltages. The results show that the relaxed graphite cells quickly reached a constant parasitic heat flow value with minimal transient effects. In contrast, the unrelaxed cells presented increased transient effects in the parasitic heat flow signal that can last more than 300 h. The electric transient originates mainly from anode overhang effects and SEI regrowth, while the thermal transient consists predominantly of SEI regrowth. Overall, the thermal signals stabilize faster than the electrical signals, giving calorimetry an advantage for faster estimation of parasitic side reactions.

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Wang, Kun, i Juntong Xi. "A method to estimate the transient fluid pressure of a piezoelectric inkjet printer using system dynamic analysis". Rapid Prototyping Journal 23, nr 6 (17.10.2017): 1130–35. http://dx.doi.org/10.1108/rpj-11-2015-0174.

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Purpose This paper aims to present a method based on dynamics to find the transient pressure at the nozzle area of a piezoelectric inkjet printer. This pressure responds to input signals of the piezoelectric driver deformation. The pressure at the nozzle is the boundary condition of the computational fluid dynamics model of the inkjet printer nozzle, and serves as the “bridge” between the piezoelectric driver actuation and the droplet generation of an inkjet printer. Design/methodology/approach The transient pressure was estimated using a fluid-solid coupling numerical model of the printerhead. In this study, a simple step-shape signal was applied. The printerhead chamber was considered to act as a linear Helmholtz resonator to determine the system transfer function between the input of driver deformation and the output of pressure. By decomposing the input signal into several simple signals, the transient pressure is the superposition of those calculated pressures. Findings The pressure values determined by transfer function and by superposition match the pressure values directly calculated by a fluid-solid coupling model. This demonstrates the rationality and practicability of the method. Originality/value This paper proposes a method to identify a proper boundary condition of pressure for numerical models that only include the fluid field around the nozzle. This strategy eliminates the need to calculate the complex and unstable fluid-solid coupling for every pattern of input. Additionally, the suitable boundary condition of transient pressure can be set rather than relying on the shape of the PZT driver deformation signal.

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Xu, Zhi, Gang Tang i Mengfu He. "Peak-Based Mode Decomposition for Weak Fault Feature Enhancement and Detection of Rolling Element Bearing". Shock and Vibration 2020 (9.04.2020): 1–10. http://dx.doi.org/10.1155/2020/8901794.

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Rolling element bearings are widely used in rotating machinery to support shafts, whose failures may affect the health of the whole system. However, strong noise interferences often make the bearing fault features submerged and difficult to be identified. Peak-based wavelet method is such a way to reduce certain noise and enhance the fault features by increasing the sparsity of monitored signals. But peak-based wavelet parameters need to be optimized due to the determined basis function and constant resolution, which will affect the efficiency of vibration signal analysis. To address these problems, a peak-based mode decomposition is proposed for weak bearing fault feature enhancement and detection. Firstly, to enhance the differences between repetitive transients and high-frequency noise, a peak-based piecewise recombination is used to convert the middle frequency parts into low-frequency ones. Then, the recombined signal is processed by empirical mode decomposition, combining with a criterion of cross-correlation coefficients and kurtosis. Subsequently, a backward peak transformation is performed to obtain the enhanced signal. Finally, the fault diagnosis is implemented by the squared envelope spectrum, whose normalized squared magnitude is used as a bearing fault indicator. The analysis results of the simulated signals and the experimental signals show that the proposed method can enhance and identify the weak repetitive transient features. The superiority of the proposed method for faint repetitive transient detection is also verified by comparing with the peak-based wavelet method.

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34

Homborg, A. M., P. J. Oonincx i J. M. C. Mol. "Wavelet Transform Modulus Maxima and Holder Exponents Combined with Transient Detection for the Differentiation of Pitting Corrosion Using Electrochemical Noise". Corrosion 74, nr 9 (25.04.2018): 1001–10. http://dx.doi.org/10.5006/2788.

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A potentially powerful tool to detect and classify corrosion mechanisms is the analysis of electrochemical noise (EN). Data analysis in the time-frequency domain using, e.g., continuous wavelet transform (CWT) allows the extraction of localized frequency information, providing information on the type of corrosion, i.e., uniform or localized corrosion, from the EN signal. The CWT provides the opportunity to analyze changes in frequency behavior of EN signals over time. In the presence of transients generated by pitting corrosion that occur only during short instants of time, this is an important property. This paper introduces the combination of automated transient detection with wavelet transform modulus maxima (WTMM) and the Holder exponent. WTMM enhances the determination of transient frequencies by indicating the ridges of a CWT spectrum. The Holder exponent, a measure of singularity of an EN signal, provides a single parameter discrimination tool based on WTMM and serves to differentiate between general corrosion and two types of pitting corrosion of stainless steel Type 304 exposed to aqueous HCl solutions of different concentrations and as such at different pH values.

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Wang, Fengli. "Pulsation Signals Analysis of Turbocharger Turbine Blades based on Optimal EEMD and TEO". Polish Maritime Research 26, nr 3 (1.09.2019): 78–86. http://dx.doi.org/10.2478/pomr-2019-0048.

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Abstract Turbocharger turbine blades suffer from periodic vibration and flow induced excitation. The blade vibration signal is a typical non-stationary and sometimes nonlinear signal that is often encountered in turbomachinery research and development. An example of such signal is the pulsating pressure and strain signals measured during engine ramp to find the maximum resonance strain or during engine transient mode in applications. As the pulsation signals can come from different disturbance sources, detecting the weak useful signals under a noise background can be difficult. For this type of signals, a novel method based on optimal parameters of Ensemble Empirical Mode Decomposition (EEMD) and Teager Energy Operator (TEO) is proposed. First, an optimization method was designed for adaptive determining appropriate EEMD parameters for the measured vibration signal, so that the significant feature components can be extracted from the pulsating signals. Then Correlation Kurtosis (CK) is employed to select the sensitive Intrinsic Mode Functions (IMFs). In the end, TEO algorithm is applied to the selected sensitive IMF to identify the characteristic frequencies. A case of measured sound signal and strain signal from a turbocharger turbine blade was studied to demonstrate the capabilities of the proposed method.

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Li, Quanchang, Xiaoxi Ding, Tao Wang, Mingkai Zhang, Wenbin Huang i Yimin Shao. "Time-frequency synthesis analysis for complex signal of rotating machinery via variational mode manifold reinforcement learning". Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science 234, nr 7 (30.12.2019): 1438–55. http://dx.doi.org/10.1177/0954406219897688.

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The transient signal caused by localized fault in rotating machinery always contains complex modulation information with heavy background noise distributed, which brings much difficulties for fault feature identification in the application of rotating machinery fault diagnosis. Focusing on the sensitive feature extraction from these complex signals, this paper proposes a novel variational mode manifold reinforcement learning (VM2RL) to adaptively construct time-frequency synthesis analysis for enhancement of transient features. First, a method of adaptive variational mode decomposition (VMD) is employed to divide the raw spectrum of the given signal into several sub-bands with different frequency modulation information. Second, an improved time-frequency manifold (ITFM) learning is introduced to gain the topological manifold structure from those sub-distributions in time-frequency domain. Then, a sound-enhanced signature of transient features on the whole time-frequency plane can be synthesized by combining those sub-TFMs from each modulated segment back to the corresponding frequency band. Finally, the time-frequency envelope spectrum for fault diagnosis is further obtained through statistically evaluating their amplitude distribution. Among them, short-frequency Fourier transform (SFFT) is introduced to transform local frequency bands into a series of TFDs which improves the computational efficiency of TFM learning. In this manner, the desired transient distribution on full time-frequency plane can be automatically reconstructed by VM2RL with manifold reinforced in a data-driven way. A simulation study and two experimental signals are both analyzed here, and fast spectral kurtosis and conventional VMD methods are also used to verify its effectiveness. Meanwhile, a quantitative analysis has been provided to further illustrate its superiority in the application of complex signal fault of rotating machinery.

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Li, Meng Da, Yu Bo Duan i Yan Wang. "Time-Frequency Analysis Method in the Transient Power Quality Disturbance Analysis Application". Applied Mechanics and Materials 700 (grudzień 2014): 99–102. http://dx.doi.org/10.4028/www.scientific.net/amm.700.99.

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This paper uses the method of S transformation to test the starting time, the end of the time, frequency and amplitude characteristics of common transient power quality signal disturbance. Through error analysis and simulation show that this method can accurately determine the disturbance occurred time and duration, and the identification and determination of disturbance can be simple and intuitive. It has the practical value and realistic significance to power quality signal interference analysis.

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Velandy, Jeyabalan. "Vector space representation of signals for transient signal analysis in transformers and shunt reactor". Electric Power Systems Research 140 (listopad 2016): 745–60. http://dx.doi.org/10.1016/j.epsr.2016.06.038.

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Crenna, Francesco, Giovanni Battista Rossi i Marta Berardengo. "Filtering Biomechanical Signals in Movement Analysis". Sensors 21, nr 13 (4.07.2021): 4580. http://dx.doi.org/10.3390/s21134580.

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Biomechanical analysis of human movement is based on dynamic measurements of reference points on the subject’s body and orientation measurements of body segments. Collected data include positions’ measurement, in a three-dimensional space. Signal enhancement by proper filtering is often recommended. Velocity and acceleration signal must be obtained from position/angular measurement records, needing numerical processing effort. In this paper, we propose a comparative filtering method study procedure, based on measurement uncertainty related parameters’ set, based upon simulated and experimental signals. The final aim is to propose guidelines to optimize dynamic biomechanical measurement, considering the measurement uncertainty contribution due to the processing method. Performance of the considered methods are examined and compared with an analytical signal, considering both stationary and transient conditions. Finally, four experimental test cases are evaluated at best filtering conditions for measurement uncertainty contributions.

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Starkhammar, Josefin, i Maria Hansson-Sandsten. "Evaluation of Seven Time-Frequency Representation Algorithms Applied to Broadband Echolocation Signals". Advances in Acoustics and Vibration 2015 (16.07.2015): 1–13. http://dx.doi.org/10.1155/2015/342503.

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Time-frequency representation algorithms such as spectrograms have proven to be useful tools in marine biosonar signal analysis. Although there are several different time-frequency representation algorithms designed for different types of signals with various characteristics, it is unclear which algorithms that are best suited for transient signals, like the echolocation signals of echolocating whales. This paper describes a comparison of seven different time-frequency representation algorithms with respect to their usefulness when it comes to marine biosonar signals. It also provides the answer to how close in time and frequency two transients can be while remaining distinguishable as two separate signals in time-frequency representations. This is, for instance, relevant in studies where echolocation signal component azimuths are compared in the search for the exact location of their acoustic sources. The smallest time difference was found to be 20 µs and the smallest frequency difference 49 kHz of signals with a −3 dB bandwidth of 40 kHz. Among the tested methods, the Reassigned Smoothed Pseudo Wigner-Ville distribution technique was found to be the most capable of localizing closely spaced signal components.

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González-Franco, José Antonio, Alberto Ruiz i Joaquín Ángel Ortuño. "Dynamic Potentiometry with an Ion-Selective Electrode: A Tool for Qualitative and Quantitative Analysis of Inorganic and Organic Cations". Chemosensors 10, nr 3 (18.03.2022): 116. http://dx.doi.org/10.3390/chemosensors10030116.

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A study of the transient potential signals obtained with a cation-selective electrode based on an ion-exchanger was carried out for solutions of the following individual cations at different concentrations: H+, Li+, Na+, K+, Rb+, Mg2+, Ca2+, choline (Ch+), acetylcholine (AcCh+), and procaine (Pr+). Three different general types of transient signals were distinguished depending on the value of the selectivity coefficient of the corresponding ion. A principal component analysis (PCA) was performed on the signals, finding that the qualitative identification of the corresponding ion from the scores of two principal components is possible. The study was extended to the transient signals of solutions containing an analyte in the presence of an interfering ion. The PCA of the corresponding signal allows for the detection of the presence of interfering ions, thus avoiding biased results in the determination of the analyte. Moreover, the two principal components of the transient signals obtained for each of the ions at different concentrations allow for the construction of calibration graphs for the quantitative determination of the corresponding ion. All the transient signals obtained experimentally in this work can be reconstructed accurately from principal components and their corresponding scores.

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Zhang, Na, i Chun Wu Liu. "Selection and Design of Excitation Signal in Test System". Journal of Physics: Conference Series 2428, nr 1 (1.02.2023): 012003. http://dx.doi.org/10.1088/1742-6596/2428/1/012003.

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Abstract Both the test system and testing technology are inseparable from the selection and construction of the excitation signal. This paper shows excitation signals including transient excitation, harmonic excitation, random signal excitation, etc, which are commonly used in the time domain, frequency domain, and correlation analysis of the stimulus-response test. Moreover, the selection and design method of excitation signals in the test system is introduced based on the principle of signal analysis and system identification, combined with research and engineering practice experience. The application of different excitation signals in modal tests and device characterization is described at the end of this paper.

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Leach, Andrew M., i Gary M. Hieftje. "Factors Affecting the Production of Fast Transient Signals in Single Shot Laser Ablation Inductively Coupled Plasma Mass Spectrometry". Applied Spectroscopy 56, nr 1 (styczeń 2002): 62–69. http://dx.doi.org/10.1366/0003702021954223.

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Low sample consumption and high achievable spatial resolution combine to make laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) an attractive direct sampling technique for the analysis of solids. These desirable characteristics are best realized when the laser ablation system is operated in a single-shot fashion, in which each laser pulse produces a transient analyte signal. The temporal width of a single-shot LA analyte transient is inversely related to the best achievable signal-to-noise ratio (S/N). Thus, production of fast transient signals is an important consideration in single-shot LA analyses. In this study we explore the effects on transient pulse width of ablation-cell volume, the diameter and length of tubing used to connect the ablation cell to the ICP, and the composition and flow rate of ablation-cell sweep gas. Minimization of ablation-cell volume and the length and diameter of the transfer tube was found to dramatically decrease the peak widths of transient signals. However, use of helium gas to sweep analyte particles from the ablation cell was found to significantly reduce the effect of cell volume on transient width. Use of a cell volume of 0.70 cm3 and optimization of other instrumental parameters produced a transient sample pulse 85 ms in duration and limits of detection in the tens of femtograms range for single-shot laser-ablation events.

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Collar, Steven, i Garth Frazier. "Acoustic array signal processing with the Stockwell transform". Journal of the Acoustical Society of America 151, nr 4 (kwiecień 2022): A36. http://dx.doi.org/10.1121/10.0010576.

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The Stockwell transform is a wavelet-like transformation based on a Fourier kernel weighted by a symmetric, frequency-scaled, time-shifted window function. Thus, it is suitable for analysis of non-stationary waveforms and transients in particular. In its discrete-time, orthogonal basis realization known as the discrete orthogonal Stockwell transform (DOST), it is possible to transform an N-point sequence in O(N log N) operations. In this presentation, we show how to perform direction-of-arrival and transient waveform estimation in the Stockwell basis in a manner that is similar to traditional multi-channel frequency-domain (discrete Fourier transform) techniques. This enhances detection of multiple transients within the same data frame sequence.

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Xie, Jingsong, Wei Cheng, Yanyang Zi i Mingquan Zhang. "Phase-based spectrum analysis method for identifying weak harmonics". Journal of Vibration and Control 24, nr 23 (16.03.2018): 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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Huang, Zhidu, Shan Li, Yubin Feng, Jie Tang, Wei Zhang, Zhimei Cui, Rongrong Wu, Jianna Ouyang i Lu Oyang. "Research on Fault Location Technology of Overhead Line Based on Non-Contact High Sensitivity Distributed Traveling Wave". Journal of Nanoelectronics and Optoelectronics 17, nr 9 (1.09.2022): 1238–44. http://dx.doi.org/10.1166/jno.2022.3319.

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Aiming at the characteristics of overhead transmission line faults and starting from the research of the fault transient current and features of traveling wave signals of the grounded transmission tower when fault occurs, this paper analyzes non-contact distributed methods of acquiring fault traveling wave signals and then puts forward one. The transient traveling wave signal designed at the earth potential terminal of the transmission line tower allows the quick and accurate acquisition of the fault signal, improving the reliability and accuracy of the fault signal. At the same time, a series of simulation and experimental analysis were carried out. The distributed non-contact fault location method is more flexible than the traditional method and can be used in the field application of overhead transmission lines to improve the fault location accuracy and search efficiency.

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Gourgiotis, Alkiviadis, Gérard Manhès, Pascale Louvat, Julien Moureau i Jérôme Gaillardet. "Transient signal isotope analysis using multicollection of ion beams with Faraday cups equipped with 1012 Ω and 1011 Ω feedback resistors". Journal of Analytical Atomic Spectrometry 30, nr 7 (2015): 1582–89. http://dx.doi.org/10.1039/c5ja00094g.

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This work is a first attempt to evaluate the potential use of 10¹² Ω amplifiers for transient signal isotope analysis. We showed how the transient signal duration influences the accuracy of the isotope ratio measurements.

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Omar, A. S., i A. H. Kamel. "Network theoretical transient analysis of signal transmission over evanescent modes". IEEE Transactions on Antennas and Propagation 51, nr 3 (marzec 2003): 595–605. http://dx.doi.org/10.1109/tap.2003.809824.

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Han, K., i T. T. Y. Wong. "Coupled-wave small-signal transient analysis of GaAs distributed amplifier". IEEE Transactions on Microwave Theory and Techniques 38, nr 1 (1990): 23–29. http://dx.doi.org/10.1109/22.44152.

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Schlaich, Andreas, Gerd Gantenbein, John Jelonnek i Manfred Thumm. "Transient Millimeter-Wave Signal Analysis With Unambiguous RF Spectrum Reconstruction". IEEE Transactions on Microwave Theory and Techniques 61, nr 12 (grudzień 2013): 4660–66. http://dx.doi.org/10.1109/tmtt.2013.2283063.

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