Sökning: "Periodicity"

Visar resultat 1 - 5 av 90 avhandlingar innehållade ordet Periodicity.

  1. 1. Testing for Periodicity and Trend in Long-Memory Processes

    Författare :Abdullah Almasri; Statistiska institutionen; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Statistics; temperature data.; sunspots data; wind speed data; varve data; Siegel’s test; Fisher’s test; periodogram; Fractional difference process; Discrete wavelet transform; operations research; programming; actuarial mathematics; Statistik; operationsanalys; programmering; aktuariematematik; Wavelets; Statistik;

    Sammanfattning : This thesis presents methods of testing the periodicity and trend for the time series, which exhibit dependence over long periods of time. Many such processes can be modeled by a class of models called fractionally differenced processes. LÄS MER

  3. 2. Acoustic excitation and transmission of lightweight structures

    Författare :Jonas Brunskog; Teknisk akustik; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; point mobility; Lamb waves; wood.; Building construction; plate excitation; cavities; near-periodicity; nearly periodic; sound insulation; timber; structural acoustics; spatial Fourier transform; resilient device; prediction model; periodic; lightweight; ISO tapping machine; airborne noise; Building acoustics; impact noise; Byggnadsteknik;

    Sammanfattning : In order to increase our knowledge of the sound transmission and radiation processes of lightweight wall and floor structures, theoretical models are needed. Detailed models may form a valuable tool. In lightweight floor structures, impact sound insulation is perhaps the most important property to consider. LÄS MER

  4. 3. Holocene development of Lake Lögurinn and Eyjabakkajökull : a multi-proxy approach

    Författare :Johan Striberger; Kvartärgeologi; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Iceland; the Holocene; lake sediments; varves; glacial meltwater variability; surge periodicity; palaeoclimate;

    Sammanfattning : The North Atlantic region has experienced significant climate fluctuations during the Holocene. It has been shown that these fluctuations affected the terrestrial environment in Iceland, including its glaciers and ice caps. LÄS MER

  5. 4. Turbomachinery Aeroacoustic Calculations using Nonlinear Methods

    Författare :Martin Olausson; Chalmers tekniska högskola; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Nonlinear; CFD; Time Spectral; CAA; Ffowcs-Williams Hawkings; Broadband; Time lag; Computational Aeroacoustics; Fan-Noise; Rotor-Stator interaction; Buffer layer; Oscillating sphere; Newton-GMRES; Computational Fluid Dynamics; Acoustic analogies; Sponge; Counter-Rotating Propfan; Harmonic Balance Technique; Tone; FWH; Chorochronic periodicity; Hybrid RANS LES;

    Sammanfattning : Noise regulations for aircraft that fly over populated areas are becoming continuously stricter. This in combination with increasing computational capabilities has boosted interest in aeroacoustic computations in the aerospace industry. LÄS MER

  7. 5. Sparse Modeling Heuristics for Parameter Estimation - Applications in Statistical Signal Processing

    Författare :Stefan Ingi Adalbjörnsson; Matematisk statistik; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; parameter estimation; sparse models; convex optimization; fundamental frequency; inharmonicity; audio localization; symbolic periodicity; alternating directions method of multipliers; N-dimensional decaying sinusoids.;

    Sammanfattning : This thesis examines sparse statistical modeling on a range of applications in audio modeling, audio localizations, DNA sequencing, and spectroscopy. In the examined cases, the resulting estimation problems are computationally cumbersome, both as one often suffers from a lack of model order knowledge for this form of problems, but also due to the high dimensionality of the parameter spaces, which typically also yield optimization problems with numerous local minima. LÄS MER