Sökning: "cryogenic"

Visar resultat 21 - 25 av 130 avhandlingar innehållade ordet cryogenic.

  1. 21. THz Vector Beam Measurement System for APEX Instrument SHeFI and Microwave Cryogenic Low Noise Amplifier Design

    Författare :Olle Nyström; Chalmers tekniska högskola; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; vector measurements; mm- and submm-wave optics; LNA; radio astronomy; cryogenic amplifier; APEX; InP HEMT; Gaussian beam;

    Sammanfattning : This licentiate thesis describes results of the author’s work on development of THz vector beam measurement system and microwave cryogenic low-noise amplifier.The first part, and the main focus, of the thesis covers the vector beam measurement system for frequency range 210-500 GHz developed to characterize/verify the cold opticsof the APEX instrument SHeFI. LÄS MER

  3. 22. Cryogenic soil processes in a changing climate

    Författare :Marina Becher; Jonatan Klaminder; Johan Olofsson; Jan Karlsson; Niclas Börlin; Philip Wookey; Umeå universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Non-sorted circle; Carbon storage; Soil motion; Terrestrial photogrammetry; Cryoturbation; Carbon fluxes; naturgeografi; Physical Geography;

    Sammanfattning : A considerable part of the global pool of terrestrial carbon is stored in high latitude soils. In these soils, repeated cycles of freezing and thawing creates soil motion (cryoturbation) that in combination with other cryogenic disturbance processes may play a profound role in controlling the carbon balance of the arctic soil. LÄS MER

  4. 23. EPR Studies of Photosystem II : Characterizing Water Oxidizing Intermediates at Cryogenic Temperatures

    Författare :Kajsa G.V. Havelius; Stenbjörn Styring; Holger Dau; Uppsala universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Biochemistry; Biokemi;

    Sammanfattning : The principles of natures own light-driven water splitting catalyst, Photosystem II (PSII), can in the future inspire us to use water as electron and proton source to generate light-driven H2 production. To mimic this challenging step, it is important to understand how the enzyme system can oxidize water. LÄS MER

  5. 24. InP HEMT Technology and Applications

    Författare :Anders Mellberg; Chalmers tekniska högskola; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Indium phosphide InP ; cryogenic LNA; high electron mobility transistor HEMT ; metal-insulator-metal capacitor; MODFET; thin film resistor; semiconductor device fabrication; MMIC;

    Sammanfattning : Indium phosphide high electron mobility transistors (InGaAs/InAlAs/InP HEMTs) exhibit the highest cut-off frequencies and the lowest microwave noise figures of all transistor technologies. Both InP HEMT technology and associated circuit demonstrators are therefore interesting to explore further. LÄS MER

  7. 25. Quantum Coherence in the Single Cooper Pair Box

    Författare :Kevin Bladh; Chalmers tekniska högskola; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; coherent oscillations; single Cooper pair box; quantum coherence; radio frequency single electron transistor; cryogenic filters;

    Sammanfattning : This thesis presents measurements of quantum coherence in a single Cooper pair box, where quantum oscillations of charge between a reservoir and a small superconducting island have been observed. The single Cooper pair box (SCB) consists of a small metallic island which is connected to a reservoir via a tunnel junction. LÄS MER