scholarly journals A fast time-frequency response based differential spectral energy protection of AC microgrids including fault location

Author(s):  
O. Dharmapandit ◽  
R. K. Patnaik ◽  
P. K. Dash
2021 ◽  
Author(s):  
Rejith K.N ◽  
Kamalraj Subramaniam ◽  
Ayyem Pillai Vasudevan Pillai ◽  
Roshini T V ◽  
Renjith V. Ravi ◽  
...  

Abstract In this work, PD patients and healthy individuals were categorized with machine-learning algorithms. EEG signals associated with six different emotions, (Happiness(E1), Sadness(E2), Fear(E3), Anger(E4), Surprise,(E5) and disgust(E6)) were used for the study. EEG data were collected from 20 PD patients and 20 normal controls using multimodal stimuli. Different features were used to categorize emotional data. Emotional recognition in Parkinson’s disease (PD) has been investigated in three domains namely, time, frequency and time frequency using Entropy, Energy-Entropy and Teager Energy-Entropy features. Three classifiers namely, K-Nearest Neighbor Algorithm, Support Vector Machine and Probabilistic Neural Network were used to observethe classification results. Emotional EEG stimuli such as anger, surprise, happiness, sadness, fear, and disgust were used to categorize PD patients and healthy controls (HC). For each EEG signal, frequency features corresponding to alpha, beta and gamma bands were obtained for nine feature extraction methods (Entropy, Energy Entropy, Teager Energy Entropy, Spectral Entropy, Spectral Energy-Entropy, Spectral Teager Energy-Entropy, STFT Entropy, STFT Energy-Entropy and STFT Teager Energy-Entropy). From the analysis, it is observed that the entropy feature in frequency domain performs evenly well (above 80 %) for all six emotions with KNN. Classification results shows that using the selected energy entropy combination feature in frequency domain provides highest accuracy for all emotions except E1 and E2 for KNN and SVM classifier, whereas other features give accuracy values of above 60% for most emotions.It is also observed that emotion E1 gives above 90 % classification accuracy for all classifiers in time domain.In frequency domain also, emotion E1 gives above 90% classification accuracy using PNN classifier.


Author(s):  
Meng-Kun Liu ◽  
Eric B. Halfmann ◽  
C. Steve Suh

A novel control concept is presented for the online control of a high-speed micro-milling model system in the time and frequency domains concurrently. Micro-milling response at high-speed is highly sensitive to machining condition and external perturbation, easily deteriorating from bifurcation to chaos. When losing stability, milling time response is no longer periodic and the frequency response becomes broadband, rendering aberrational tool chatter and probable tool damage. The controller effectively mitigates the nonlinear vibration of the tool in the time domain and at the same time confines the frequency response from expanding and becoming chaotically broadband. The simultaneous time-frequency control is achieved through manipulating wavelet coefficients, thus not limited by the increasing bandwidth of the chaotic system — a fundamental restraint that deprives contemporary controller designs of validity and effectiveness. The feedforward feature of the control concept prevents errors from re-entering the control loop and inadvertently perturbing the sensitive micro-milling system. Because neither closed-form nor linearization is required, the innate, genuine features of the micro-milling response are faithfully retained.


2021 ◽  
Author(s):  
Resmi Suresh ◽  
Raghunathan Rengaswamy

Abstract Frequency response analysis (FRA) of systems is a well-researched area. For years, FRA has been performed using input signals, which are a series of sinusoids or a sum of sinusoids. This results in large experimentation time, particularly when the system has to be probed at lower frequencies. In this work, we describe a previously unknown time-frequency duality for linear systems when probed through chirp signals. We show that the entire frequency response can be extracted with a single chirp signal by extending the notion of instantaneous frequency to both the input and output signals. It is surprising that this powerful result had not been uncovered given that FRA has been used in multiple disciplines for more than hundred years. This result has the possibility of completely revolutionizing methods used for frequency response analysis. Simulation studies that support the main result are described. While this result is of relevance in multiple areas, we demonstrate the potential impact of this result in electrochemical impedance spectroscopy.


Author(s):  
Frank Tarantini ◽  
Georges Al-Khoury ◽  
Thomas Panetta ◽  
Michael Zenilman ◽  
Harry L. Graber ◽  
...  

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