Search for dissertations about: "pulse waveforms"

Showing result 1 - 5 of 20 swedish dissertations containing the words pulse waveforms.

  2. 1. Characterization of Electrical Insulation Exposed to Arbitrary Voltage Waveforms

    Author : Björn Sonerud; Chalmers tekniska högskola; []
    Keywords : TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; arbitrary voltage waveforms; partial discharge; diagnostics; dielectric response measurement; signal processing; electrical treeing; dielectric heating.;

    Abstract : The extensive use of power electronics in power systems today gives rise to other voltage waveforms than the conventional 50/60 Hz sinusoidal and consequently other types of electric stress act on high voltage insulating materials. Previous studies has shown that Pulse Width Modulated (PWM) voltages and similar waveforms increase stress in Adjustable Speed Drives (ASD) as compared with sinusoidal waveforms and it has also been shown that partial discharge (PD) activity is intensified during PWM voltages and that rise time of square like pulses affect PD inception voltage. READ MORE

  4. 2. Cerebral blood flow and intracranial pulsatility studied with MRI : measurement, physiological and pathophysiological aspects

    Author : Anders Wåhlin; Anders Eklund; Jan Malm; Richard Birgander; William G Bradley; Umeå universitet; []
    Keywords : TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Arterial Pulsatility; cerebrospinal fluid; cerebral blood flow; venous flow; intracranial pressure; pulse pressure; dementia; hippocampus; multiple sclerosis; magnetic resonance imaging; radiofysik; radiation physics;

    Abstract : During each cardiac cycle pulsatile arterial blood inflates the vascular bed of the brain, forcing cerebrospinal fluid (CSF) and venous blood out of the cranium. Excessive arterial pulsatility may be part of a harmful mechanism causing cognitive decline among elderly. READ MORE

  5. 3. Arterial pulse wave analysis. With special reference to vasoactive and anaesthetic drugs and to heart lung interactions

    Author : Staffan Söderström; Göteborgs universitet; []
    Keywords : pulse; blood pressure physiology; hypertension; aged; vasodilation; ventricular function; left; nitroglycerin; coronary disease; artificial respiration; fentanyl.;

    Abstract : In the young systolic arterial pressures (SAP) are higher in the radial artery than in the proximal aorta. Due to increased large artery stiffness and early pulse wave reflection aortic SAP increases more with age than peripheral SAP. READ MORE

  6. 4. Development and evaluation of non-invasive ultrasonic methods for arterial characterization

    Author : Anders Eriksson; Avdelningen för Biomedicinsk teknik; []
    Keywords : TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Instrumentation technology; TDI; Tissue Doppler imaging; Arterial characterization; Non-invasive; Flow generation; PWV; Pulse wave velocity; Mät- och instrumenteringsteknik; Ultrasound; Vascular impedance;

    Abstract : As cardiovascular diseases have been the most common cause of mortality in the western world for decades, the demand for appropriate diagnostic methods is obvious. To facilitate the examination non-invasive methods are preferable since they do not require sensors within the circulation system. READ MORE

  7. 5. Characterisation of the Neutron Wall and of Neutron Interactions in Germanium-Detector Systems

    Author : Joa Ljungvall; Johan Nyberg; Andres Gadea; Uppsala universitet; []
    Keywords : NATURVETENSKAP; NATURAL SCIENCES; Nuclear physics; High-purity Ge detectors; Liquid scintillator detectors; Neutron scattering; Digital electronics; Time-of-flight technique; Pulse-shape simulation and analysis; Monte Carlo simulations; Geant4; Gamma-ray tracking; AGATA; Neutron Wall; Kärnfysik; Nuclear physics; Kärnfysik;

    Abstract : A Monte Carlo simulation of the Neutron Wall detector system has been performed using Geant4, in order to define optimum conditions for the detection and identification of multiple neutrons. Emphasis was put on studying the scattering of neutrons between different detectors, which is the main source of the apparent increase of the number of detected neutrons. READ MORE