Sökning: "High frequency testing"

Visar resultat 1 - 5 av 137 avhandlingar innehållade orden High frequency testing.

  1. 1. End-Shield Bridges for High-Speed Railway : Full scale dynamic testing and numerical simulations

    Författare :Hesham Elgazzar; Jean-Marc Battini; Mahir Ülker-Kaustell; Morgan Johansson; KTH; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; high-speed railway; end-shield bridges; structural dynamics; soil structure interaction; full scale bridge testing; controlled forced excitation; hydraulic bridge exciter; frequency response function; Civil and Architectural Engineering; Byggvetenskap;

    Sammanfattning : The increasing need for High-Speed Railway (HSR) to reduce the travelling time requires increasing research within this field. Bridges are main components of any railway network, including HSR networks, and the optimization of their design for this purpose would contribute to a faster and more cost effective development of the HSR network. LÄS MER

  3. 2. Very high cycle fatigue of automotive steels : Testing and computation at 20 kHz

    Författare :Mohamed Sadek; Jens Bergström; Nils Hallbäck; Ulrich Krupp; Karlstads universitet; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Very high cycle fatigue; ultrasonic fatigue testing; automotive steels; fatigue strength; stress intensity computation; crack growth; Materialteknik; Materials Engineering;

    Sammanfattning : Mechanical fatigue failure occurs in components subjected to cyclic loading. A crack initiates at critical regions in the component and propagates during repeated loading. The expected fatigue life depends on the level, type and frequency of the loading. LÄS MER

  4. 3. High-Frequency ECG in Ischemic Heart Disease

    Författare :Jonas Pettersson; Avdelningen för klinisk genetik; []
    Nyckelord :MEDICIN OCH HÄLSOVETENSKAP; MEDICAL AND HEALTH SCIENCES; MEDICIN OCH HÄLSOVETENSKAP; MEDICAL AND HEALTH SCIENCES; radiology; Clinical physics; high-frequency QRS components; electrocardiogram; myocardial infarction; myocardial ischemia; Ischemic heart disease; tomography; medical instrumentation; Klinisk fysiologi; radiologi; tomografi; medicinsk instrumentering;

    Sammanfattning : Analysis of high-frequency QRS components (HF-QRS) is one of the emerging methods for increasing the diagnostic performance of the electrocardiogram (ECG). The overall objective of the thesis is to investigate whether analysis of HF-QRS has the ability to provide information about ischemic heart disease and so serve as an adjunctive diagnostic tool in several clinical situations. LÄS MER

  5. 4. Elastic Wave Scattering by Cracks - Interfacial Forces and High Frequency Diffraction

    Författare :Gert Persson; Chalmers tekniska högskola; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; ultrasonic testing; Wiener-Hopf calculations; Geometrical Theory of Diffraction; edge diffracted body waves; PEDGE; two-dimensional diffraction; geometrical elastodynamic waves;

    Sammanfattning : This thesis treats elastic wave scattering by cracks with interfacial forces. The results are of practical interest in ultrasonic testing and includes development of numerical methods used to predict such testing. First the canonical problem of two-dimensional (2-D) diffraction from a semi-infinite crack is solved. LÄS MER

  7. 5. Dynamic Soil-Structure Interaction Analysis of High-Speed Railway Bridges : Efficient modeling techniques and Experimental testing

    Författare :Abbas Zangeneh Kamali; Costin Pacoste; Raid Karoumi; Andreas Andersson; Pedro Galvín; KTH; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Railway bridge dynamics; Soil-structure interaction; Resonance; Analytical solution; Non-proportional damping; Complex mode; Field measurements; FE Model updating; Järnvägsbrodynamik; Jord-bro interaktion; Resonans; Analytisk lösning; Icke-proportionell dämpning; Komplex mod; Fältmätningar; FE Modelluppdatering; Structural Engineering and Bridges; Bro- och stålbyggnad;

    Sammanfattning : The work reported in this thesis presents a general overview of the resonant response of high-speed railway bridges considering soil-structure interaction. The study aims to identify the effect of the surrounding and underlying soil on the global stiffness and damping of the structural system. LÄS MER