Sökning: "short time Fourier transform"

Visar resultat 1 - 5 av 19 avhandlingar innehållade orden short time Fourier transform.

  1. 1. Fourier transform and Vernier spectroscopy using optical frequency combs

    Författare :Amir Khodabakhsh; Aleksandra Foltynowicz; Ove Axner; Frans Harren; Umeå universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; optical frequency comb spectroscopy; molecular absorption; resonant cavity; Fourier transform spectroscopy; Vernier spectroscopy; fysik; Physics;

    Sammanfattning : Optical frequency comb spectroscopy (OFCS) combines two previously exclusive features, i.e., wide optical bandwidth and high spectral resolution, enabling precise measurements of entire molecular bands and simultaneous monitoring of multiple gas species in a short measurement time. LÄS MER

  3. 2. Stability and Statistical Analysis of Transient Waves in Fusion Plasmas

    Författare :Gergö Pokol; Chalmers tekniska högskola; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; short-time Fourier transform; transient MHD mode; wavelet transform; quasi-linear diffusion; runaway electron; transient transport; stellarator; tokamak disruption; fusion plasma physics; whistler wave;

    Sammanfattning : Thermonuclear energy generation in magnetically confined plasmas offers an appealing energy source for coming generations. Some of the still unsolved problems in fusion plasma physics involve plasma transport and stability of plasma waves. Two such problems are addressed in the present thesis. LÄS MER

  4. 3. High Resolution Spectroscopy of Singly Charged Ions : Applications of Laser and Fourier Transform Techniques

    Författare :Jonas Gurell; Sven Mannervik; Richard Holt; Stockholms universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Atomic physics; Atomfysik; fysik; Physics;

    Sammanfattning : This thesis presents measurements of fundamental properties of singly charged ionic systems including spectral wavelengths, lifetimes of excited states and branching fractions with the main focus on time resolved laser spectroscopy of stored ions providing lifetime measurements of metastable states. The results of these measurements have been used to determine energy levels and transition probabilities of the studied systems. LÄS MER

  5. 4. Adapting Bases Using the Synchronized Short Time Fourier Transform and Non-negative Matrix Factorization

    Författare :Ruairí de Fréin; Scott T. Rickard; Barak A. Pearlmutter; University College Dublin; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Tillämpad matematik och beräkningsmatematik; Applied and Computational Mathematics;

    Sammanfattning : .... LÄS MER

  7. 5. High resolution time-frequency representations

    Författare :Isabella Reinhold; Statistical Signal Processing Group; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; NATURVETENSKAP; NATURAL SCIENCES; time-frequency analysis; non-stationary signals; multi-component signals; IF estimation; reassignment;

    Sammanfattning : Non-stationary signals are very common in nature, e.g. sound waves such as human speech, bird song and music. It is usually meaningful to describe a signal in terms of time and frequency. LÄS MER