Sökning: "Resonance"

Visar resultat 16 - 20 av 1907 avhandlingar innehållade ordet Resonance.

  1. 16. Stochastic Resonance and Noise-Assisted Signal Transfer : On Coupling Effects of Stochastic Resonators and Spectral Optimization of Fluctuations in Random Network Switches

    Författare :Peter Hammerstein; Claes Granqvist; Laszlo Kish; Hans Liljenström; Uppsala universitet; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Engineering physics; stochastic resonance; nonlinear stochastic dynamics; noise and fluctuations; magnetic domains; Teknisk fysik; Engineering physics; Teknisk fysik;

    Sammanfattning : Recent research shows that noise or random fluctuations must not always be destructive in Nature by degrading system performance. On the contrary, in nonlinear systems they can synchronize systems or enhance the quality of signal transmission. The latter possibility is reported in the thesis. LÄS MER

  3. 17. Cerebral blood flow distribution, collateral function and pulsatility in healthy and in patients with symptomatic carotid stenosis  : a magnetic resonance imaging approach

    Författare :Laleh Zarrinkoob; Jan Malm; Anders Eklund; Khalid Ambarki; Sepideh Amin-Hanjani; Umeå universitet; []
    Nyckelord :MEDICIN OCH HÄLSOVETENSKAP; MEDICAL AND HEALTH SCIENCES; Aging; Arterial pulsatility; Carotid stenosis; Cerebral arteries; Cerebral blood flow; Cerebral collateral blood flow; Circle of Willis; Phase contrast magnetic resonance imaging;

    Sammanfattning : Background: For the detection and treatment of early cerebral vascular disease it is of paramount importance to first understand the normal physiology of the cerebral vasculature, and subsequently, to understand how and when pathology can develop from that. This is especially important as the population above 65 years of age is increasing and aging itself is an established risk factor for the development of cerebral vascular disease. LÄS MER

  4. 18. Tactile sensing of prostate cancer : a resonance sensor method evaluated using human prostate tissue in vitro

    Författare :Ville Jalkanen; Olof Lindahl; Britt Andersson; Tomas Jansson; Umeå universitet; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; tactile resonance sensor; prostate tissue; prostate cancer; stiffness; density; elastic; variations; tissue histology; Medical engineering; Medicinsk teknik;

    Sammanfattning : Prostate cancer is the most frequent type of cancer in men in Europe and the USA. The methods presently used to detect and diagnose prostate cancer are inexact, and new techniques are needed. LÄS MER

  5. 19. Spectral analysis and magnetic resonance spectroscopy

    Författare :Tomas Sundin; Uppsala universitet; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Nonparametric spectral analysis; magnetic resonance spectroscopy; parameter estimation; maximum likelihood estimation; nonlinear least squares; Signal processing; Signalbehandling; Signal Processing; Signalbehandling;

    Sammanfattning : This dissertation is concerned with nonparametric approaches for spectral analysis (SA) and algorithms for magnetic resonance spectroscopy (MRS) data analysis.A method to obtain the optimal smoothing window for the class of SA methods based on local smoothing of the periodogram is proposed. LÄS MER

  7. 20. On contrast-enhanced magnetic resonance angiography of the aortoiliac arteries

    Författare :Johan Wikström; Uppsala universitet; []
    Nyckelord :MEDICIN OCH HÄLSOVETENSKAP; MEDICAL AND HEALTH SCIENCES; Oncology; Magnetic resonance imaging; Magnetic resonance angiography; Contrast media; Arteriosclerosis; Iliac artery; Blood pressures; Onkologi; Oncology; Onkologi; radiologi; Radiology;

    Sammanfattning : In contrast-enhanced magnetic resonance angiography (CE-MRA),vascular signal is produced by the acquisition of a T1-weighted magnetic resonance imaging scan while the presence of a contrast agent induces a low T1 in blood. In this thesis,CE-MRA of the aortoiliac arteries was evaluated. LÄS MER