Sökning: "time-frequency analysis"

Visar resultat 1 - 5 av 42 uppsatser innehållade orden time-frequency analysis.

  1. 1. Log Frequency Analysis for Anomaly Detection in Cloud Environments

    Master-uppsats, Blekinge Tekniska Högskola/Institutionen för programvaruteknik

    Författare :Prathyusha Bendapudi; [2024]
    Nyckelord :Log Analysis; Log Frequency Patterns; anomaly detection; machine learning; cloud environments;

    Sammanfattning : Background: Log analysis has been proven to be highly beneficial in monitoring system behaviour, detecting errors and anomalies, and predicting future trends in systems and applications. However, with continuous evolution of these systems and applications, the amount of log data generated on a timely basis is increasing rapidly. LÄS MER

  3. 2. Unsupervised Detection of Interictal Epileptiform Discharges in Routine Scalp EEG : Machine Learning Assisted Epilepsy Diagnosis

    Uppsats för yrkesexamina på avancerad nivå, Uppsala universitet/Avdelningen Vi3

    Författare :Shuai Shao; [2023]
    Nyckelord :EEG; electroencephalography; IED; interictal epileptiform discharges; spike detection; epilepsy; unsupervised; Fourier transform; STFT; short-time Fourier transform; CWT; continuous wavelet transform; DWT; discrete wavelet transform; ML; machine learning; ANN; artificial neural network; CNN; convolutional neural network; autoencoder; HMM; hidden Markov model; ECS; Euclidean distance of cumulative spectrum;

    Sammanfattning : Epilepsy affects more than 50 million people and is one of the most prevalent neurological disorders and has a high impact on the quality of life of those suffering from it. However, 70% of epilepsy patients can live seizure free with proper diagnosis and treatment. Patients are evaluated using scalp EEG recordings which is cheap and non-invasive. LÄS MER

  4. 3. Vibroacoustic Analysis of an OLTC Diverter Switch for Condition Monitoring : Time frequency analysis with Fourier and wavelet transform in combination with multivariate logistic regression for condition monitoring of OLTC diverter switch

    Uppsats för yrkesexamina på avancerad nivå, Uppsala universitet/Avdelningen för systemteknik

    Författare :Simon Persson; [2023]
    Nyckelord :Wavelet transform; CWT; logistic regression; machine learning; ML; vibroacoustic analysis; time frequency analysis; tap changer; diverter switch; power transformer; classification; prediction; condition; vibrations; state prediction; Hitachi Energy;

    Sammanfattning : Vibrations are everywhere around us all the time and we often recognise them as sounds that we can hear and analyse with our brain. In this thesis, data that has been gathered from a diverter switch (DS) in a controlled environment, is analysed. LÄS MER

  5. 4. Estimation of respiratory frequency from Heart Rate Variability

    Master-uppsats, Lunds universitet/Matematisk statistik

    Författare :Daniel Ågärd; [2023]
    Nyckelord :time-frequency analysis; multitaper spectrogram; Optimization; signal processing; heart rate variability; Mathematics and Statistics;

    Sammanfattning : In this master's thesis the ability to estimate the respiratory frequency from heart rate variability measurement is analyzed. The goal was to implement a solution that is easily transferable to real time. LÄS MER

  7. 5. Optimal Multitaper Spectrograms

    Master-uppsats, Lunds universitet/Matematisk statistik

    Författare :Markus Ydreskog; [2023]
    Nyckelord :Time-frequency analysis; Multitaper spectrogram; Optimization; Wigner distribution; Mathematics and Statistics;

    Sammanfattning : Multitaper spectrograms have been proposed as a method of improving the spectrogram as a time-frequency representation (TFR). This thesis aimed to investigate both previously used and new methods for combining multitaper spectrograms of a Gaussian signal and a chirp. LÄS MER