Sökning: "shape selective"

Visar resultat 1 - 5 av 91 avhandlingar innehållade orden shape selective.

  1. 1. Thick Frequency Selective Structures

    Författare :Björn Widenberg; Institutionen för elektro- och informationsteknik; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; acoustics; Elektromagnetism; optik; akustik; optics; Electromagnetism; Energy Saving Window; Radome; Finite Elemente Method; Frequency Selective Structure; Mode Matching Technique;

    Sammanfattning : This thesis presents a new method that can handle a general thick Frequency Selective Structure (FSS), that consists of an arbitrary number of aperture layers and dielectric layers. The method is based on the Mode Matching Technique (MMT) and the finite element method (FEM). The thesis consists of a General Introduction and five scientific papers. LÄS MER

  3. 2. Analysis of PCBs with special emphasis on comprehensive two-dimensional gas chromatography of atropisomers

    Författare :Mikael Harju; Umeå universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Environmental chemistry; PCB; Atropisomers; Chiral; GC×GC; Enantiomeric barriers; Seal; polar; shape selective; Cyclodextrin; 2D; ECD; FID; TOF-MS; Comprehensive two-dimensional GC; Miljökemi; Environmental chemistry; Miljökemi; analytisk kemi; Analytical Chemistry;

    Sammanfattning : There are 209 PCB congeners, 136 of which have been found in technical PCB mixtures and hence may be found in the environment as a result of either intentional or unintentional release. The identification and quantification of the congeners are difficult due to analytical bias from coeluting PCBs and other persistent organic pollutants. LÄS MER

  4. 3. Heterogeneous Integration of Shape Memory Alloysfor High-Performance Microvalves

    Författare :Henrik Gradin; Göran Stemme; Peter Woias; KTH; []
    Nyckelord :Microelectromechanical systems; MEMS; silicon; wafer-level; integration; heterogeneous integration; wafer bonding; Au-Si; eutectic bonding; release etching; electrochemical etching; microvalves; microactuators; shape memory alloy; SMA; NiTinol; TiNi; NiTi; cold-state reset; bias spring; gate valves; wire bonding;

    Sammanfattning : This thesis presents methods for fabricating MicroElectroMechanical System (MEMS) actuators and high-flow gas microvalves using wafer-level integration of Shape Memory Alloys (SMAs) in the form of wires and sheets. The work output per volume of SMA actuators exceeds that of other microactuation mechanisms, such as electrostatic, magnetic and piezoelectric actuation, by more than an order of magnitude, making SMA actuators highly promising for applications requiring high forces and large displacements. LÄS MER

  5. 4. 100 million years of shark macroevolution : A morphometric dive into tooth shape diversity

    Författare :Mohamad Bazzi; Per Ahlberg; Matt Friedman; Uppsala universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Sharks; Macroevolution; Extinction recovery dynamics; Geometric Morphometrics; Morphospace-Disparity Framework; Teeth; Biology with specialization in Evolutionary Organismal Biology; Biologi med inriktning mot evolutionär organismbiologi;

    Sammanfattning : Few vertebrate clades exhibit the evolutionary longevity and versatility of sharks, which constitute nearly half of all current chondrichthyan biodiversity and represent an ecological diversity of mid-to-apex trophic-level predators in both marine and freshwater environments. The rich fossil record of shark teeth from Mesozoic and Cenozoic rocks also makes the group amenable to large-scale quantitative analyses. LÄS MER

  7. 5. Speciation genomics in Ficedula flycatchers

    Författare :Madeline Chase; Carina Mugal; Chris Jiggins; Uppsala universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; NATURVETENSKAP; NATURAL SCIENCES; recombination; linked selection; selective sweeps; sex chromosomes; structural variation; birds; genome assembly; Biology with specialization in Evolutionary Genetics; Biologi med inriktning mot evolutionär genetik;

    Sammanfattning : Understanding what evolutionary processes have shaped patterns of genomic differentiation between species is a major aim of speciation genomics. However, disentangling the role of different processes that generate similar patterns remains a substantial challenge. LÄS MER