Sökning: "Ultra sound"
Visar resultat 1 - 5 av 6 avhandlingar innehållade orden Ultra sound.
1. Method development for isotope analysis of trace and ultra-trace elements in environmental matrices
Sammanfattning : The increasing load of toxic elements entering the ecosystems, as a consequence of anthropogenic processes, has grown public awareness in the last decades, resulting in a great number of studies focusing on pollution sources, transport, distribution, interactions with living organisms and remediation. Physical/chemical processes that drive the uptake, assimilation, compartmentation and translocation of heavy metals in biota has received a great deal of attention recently, since elemental concentrations and isotopic composition in biological matrices can be used as probes of both natural and anthropogenic sources. LÄS MER
2. Dissimilar joining of aluminium to ultra-high strength steels by friction stir welding
Sammanfattning : Multi-material structures are increasingly used in vehicle bodies to reduce weight of cars. The use of these lightweight structures is driven by requirements to improve fuel economy and reduce CO2 emissions. The automotive industry has replaced conventional steel components by lighter metals such as aluminium alloy. LÄS MER
3. Adaptive blind deconvolution using third-order moments : exploiting asymmetry
Sammanfattning : This thesis focuses on the use of third-order statistics in adaptive blind deconvolution of asymmetric impulsive signals. Traditional methods are typically based on fourthorder moments, which can discriminate signals with heavy-tailed probability functions (i.e. `spiky' signals) from corresponding filtered versions. LÄS MER
4. Fluid mechanics of fibre suspensions related to papermaking
Sammanfattning : This thesis deals with fluid dynamic mechanisms related to papermaking, specif- ically: the initial dewatering mechanisms during roll-forming and fibre motion in sedimentation and in shear flow. Pressure and wire position measurements have been conducted in a model resembling the forming zone and the measured pressure distributions are shown to have more complex patterns than the simple model p / T/R (where T is the wire tension and R is the roll radius). LÄS MER
5. EMG and strength in trunk and hip muscles
Sammanfattning : The overall aim of this thesis was to study the myouelectric activity of all major muscles involved in the movements and stabilization of the trunk, pelvis and hips during training exercises, postures, motor tasks, maximal strength performance and locomotion. By use of ultra-sound, EMG electrodes could be guided safely and accurately into muscles situated even close to the spinal column, such as psoas, quadratus lumborum and deep parts of erector spinae. LÄS MER
