Avancerad sökning

Visar resultat 1 - 5 av 137 avhandlingar som matchar ovanstående sökkriterier.

  1. 1. Road surface characterization using near infrared spectroscopy

    Författare :Johan Casselgren; Matti Kutila; Luleå tekniska universitet; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Spektroskopi; Väglagsklassificering; Friktion; Väglagskarakterisering; Experimental Mechanics; Experimentell mekanik;

    Sammanfattning : This thesis presents a technology and method for classifying and characterizing different road conditions such as dry asphalt and asphalt covered with water, ice and snow. The method uses light sources of different wavelengths to illuminate the road surface and a detector to measure the reflected light from the road surfaces, dependent on how the surface have absorbed, scattered and polarized the light it is possible to classify the road condition. LÄS MER

  3. 2. Continuous-filtering Vernier spectroscopy

    Författare :Chuang Lu; Aleksandra Foltynowicz; Ove Axner; Wei Ren; Umeå universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; spectroscopy; spectrometer; laser; optical frequency comb; optical cavity; NIR; MIR; flame; robust; time resolution; spectrum; fysik; Physics;

    Sammanfattning : Continuous-filtering Vernier spectroscopy (CF-VS) is a laser-based detection technique that combines the broad spectral coverage of an optical frequency comb (OFC) with the enhanced interaction length provided by an optical cavity. The resonances of the cavity filter the OFC to a small group of comb modes that probe the transitions of the species present in the cavity. LÄS MER

  4. 3. Formation and Dynamics of Molecular Excitons and their Fingerprints in Nonlinear Optical Spectroscopy

    Författare :Pär Kjellberg; Kemisk fysik; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; supraledare; magnetisk resonans; spektroskopi; Physical chemistry; Fysikalisk kemi; Photochemistry; Fotokemi; Kondenserade materiens egenskaper:elektronstruktur; magnetiska och optiska ; egenskaper elektriska; supraconductors; magnetic resonance; relaxation; spectroscopy; Fysik; Chemistry; Kemi; Condensed matter:electronic structure; electrical; Physics; Redfield relaxation theory ; Inhomogeneous broadening ; Time-dependent density functional theory ; Conjugated polymers ; Three-pulse photon echo ; Molecular excitons ; magnetic and optical properties; Nonlinear spectroscopy ;

    Sammanfattning : An efficient transfer of energy in molecular systems has proven to be of fundamental importance both in nature and industrial applications. The ability of molecules to work together forming collective excitations, so-called excitons, plays a key role in for example the extraordinary fast energy transfer involved in the first steps of photosynthesis. LÄS MER

  5. 4. Laboratory and stellar spectroscopy of the complex ions Fe+, Mo+, Th+ and U+

    Författare :Hampus Nilsson; Astronomi - Genomgår omorganisation; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; molybdenum; iron; thorium; uranium.; Atomic and molecular physics; Atom- och molekylärfysik; Astronomy; space research; cosmic chemistry; Astronomi; rymdvetenskap; kosmisk kemi; Condensed matter:electronic structure; electrical; spektroskopi; magnetisk resonans; supraledare; magnetiska och optiska ; egenskaper elektriska; Kondenserade materiens egenskaper:elektronstruktur; spectroscopy; relaxation; magnetic resonance; magnetic and optical properties; supraconductors; astrophysics; radiative lifetimes; oscillator strengths; term analysis; Fourier transform spectroscopy; branching fractions; Fysicumarkivet A:2002:Nilsson;

    Sammanfattning : The new generation of high resolution astronomical instruments such as the Hubble Space Telescope (HST) or the Very Large Telescope (VLT) has renewed the demand for accurate atomic parameters like wavelengths, oscillator strengths and line profiles accompanied by reliable uncertainty estimates. Fourier transform spectroscopy has proven to be a powerful tool when measuring these parameters. LÄS MER

  7. 5. Quantitative Modeling of Gain in Quantum Cascade Lasers under Operational Intensities

    Författare :David Winge; Matematisk fysik; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; non-linear response; quantum cascade lasers; modelling; Non-equilibrium Green s functions; Gain clamping; Fysicumarkivet A:2016:Winge; kvantkaskadlaser; terahertz; infrarött; Halvledarfysik; spektroskopi; simulering;

    Sammanfattning : This thesis adresses modeling of quantum cascade lasers using non-equilibrium Green’s functions. Focus lies on the quantitative modeling of the gain when the systems are exposed to strong laser fields, as under realistic opertional conditions. LÄS MER