Sökning: "Resonance frequency"

Visar resultat 21 - 25 av 313 avhandlingar innehållade orden Resonance frequency.

  1. 21. Vibrational energy harvesting for sensors in vehicles

    Författare :Johan Bjurström; Chalmers tekniska högskola; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; piezoelectric; anti-resonance; electromagnetic induction; prescribed displacement; low frequency; nonlinear dynamics; small amplitude excitation; automotive safety; vibration energy harvesting; unified modeling;

    Sammanfattning : The miniaturization of semiconductor technology and reduction in power requirements have begun to enable wireless self-sufficient devices, powered by ambient energy. To date the primary application lies in generating and transmitting sensory data. LÄS MER

  3. 22. Cracking in Reinforced Concrete Structures Due to Imposed Deformations

    Författare :Agnes Nagy; Avdelningen för Konstruktionsteknik; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; minimum reinforcement; cracking; softening; shrinkage; cooling; imposed deformations; conversion formula; static E-modulus; damping coefficient; resonance frequency; dynamic E-modulus; constitutive model; thermal stress; hydration process; reinforced concrete structure; early age; crack control; Building construction; Byggnadsteknik;

    Sammanfattning : This thesis is concerned with modeling of the cracking process in reinforced concrete due to imposed deformations. Cracking is investigated both at early ages, during hydration, and at mature age when the final properties of the concrete are reached. LÄS MER

  4. 23. Radio Frequency Systems for NMR Imaging: Coil Development and Studies of Non-Thermal Biological Effects

    Författare :Lars Malmgren; Lunds universitet; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; anechoic chamber; TEM transmission cells; FDTD; circularly polarized electromagnetic fields; reduced coupling; noise matching; matching networks; low noise amplifiers; upper thoracic spine; surface coils; Nuclear magnetic resonance; magnetic resonance imaging; non-thermal biological effects; blood-brain barrier; Electronics; Elektronik;

    Sammanfattning : This thesis concerns both design and optimization of NMR imaging systems and studies on non-thermal biological effects of electromagnetic fields. These two research fields are linked together by the fact that humans are subject to static and pulsed magnetic fields as well as to magnetic radio frequency fields (RF) during an NMR imaging investigation. LÄS MER

  5. 24. Nonlinear Acoustics Applied to NonDestructive Testing

    Författare :Kristian Haller; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; nonlinear acoustics; nondestructive testing; activation density; slow dynamics; resonance frequency; nonlinear wave modulation spectroscopy; harmonic generation; trapped modes; open resonator; sweep rate;

    Sammanfattning : Sensitive nonlinear acoustic methods are suitable for material characterization. This thesis describes three nonlinear acoustic methods that are proven useful for detection of defects like cracks and delaminations in solids. LÄS MER

  7. 25. Hydrodynamic Modelling for a Point Absorbing Wave Energy Converter

    Författare :Jens Engström; Jan Isberg; Mats Leijon; Antonio Sarmento; Uppsala universitet; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; NATURVETENSKAP; NATURAL SCIENCES; Ocean wave energy; Point absorber; Wave energy converter; Wave energy transport; Polychromatic wave; Linear generator; Resonance; Finite depth; Modelling; Engineering Science with specialization in Electronics; Teknisk fysik med inriktning mot elektronik;

    Sammanfattning : Surface gravity waves in the world’s oceans contain a renewable source of free power on the order of terawatts that has to this date not been commercially utilized. The division of Electricity at Uppsala University is developing a technology to harvest this energy. LÄS MER