Sökning: "saturation magnetization"

Visar resultat 1 - 5 av 22 avhandlingar innehållade orden saturation magnetization.

1. 1. Electromagnetic Modelling of Power Transformers with DC Magnetization

   Författare :Seyed Ali Mousavi; Göran Engdahl; S. V. Kulkarni; KTH; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Transformer; Hysteresis; DC magnetization; GICs; FEM; reluctance network method;

   Sammanfattning : DC currents that flow through the ground can be injected to the star windings of power transformers from their grounded neutral points and close their path with transmission lines. The geomagnetically induced currents (GICs) and AC/DC convertors of high voltage direct current (HVDC) systems are the sources of such DC currents. LÄS MER

3. 2. Materials for Magnetic Recording Applications

   Författare :Till Burkert; Olle Eriksson; Lars Nordström; Stefan Blügel; Uppsala universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Physics; magnetic materials; magnetic anisotropy; saturation magnetization; magnetic data storage; superlattice; hydrogen; density functional theory; first-principles calculations; two-dimensional magnetism; FP-LMTO; EXAFS; MOKE; Fysik; Physics; Fysik;

   Sammanfattning : In the first part of this work, the influence of hydrogen on the structural and magnetic properties of Fe/V(001) superlattices was studied. The local structure of the vanadium-hydride layers was determined by extended x-ray absorption fine structure (EXAFS) measurements. LÄS MER

4. 3. Gradient echo-based quantitative MRI of human brain at 7T : Mapping of T1, MT saturation and local flip angle

   Författare :Hampus Olsson; Lund Medicinsk strålningsfysik; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; MR studies; magnetic resonance MR ; 7 Tesla; T1 mapping; magnetization transfer saturation; Flip angle mapping; spoiled gradient echo; MR studies; magnetic resonance MR ; 7T; T1 mapping; magnetization transfer saturation; Flip angle mapping; spoiled gradient echo;

   Sammanfattning : Quantitative MRI (qMRI) refers to the process of deriving maps of MR contrast parameters, such as relaxation times, from conventional images. If the qMRI maps have a high degree of precision and a low degree of bias, they can be compared longitudinally, across subjects, and (ideally) between measurement protocols and research sites. LÄS MER

5. 4. Electromagnetic Modelling of Power Transformers for Study and Mitigation of Effects of GICs

   Författare :Seyedali Mousavi; Göran Engdahl; Ebrahim Rahimpour; KTH; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; transformer; hysteresis; DC magnetization; GMD; GICs; FEM; reluctance network method; low frequency transients; core losses; winding losses; eddy current losses; transformator; hysteresis; DC; likströmsmagnetisering; GMD; GIC; FEM; reluktansnätverksmodell; lågfrekventa transienter; kärnförluster; lindningsförluster; virvelströmsförluster; Electrical Engineering; Elektro- och systemteknik;

   Sammanfattning : Geomagnetic disturbances that result from solar activities can affect technological systems such as power networks. They may cause DC currents in power networks and saturation of the core in power transformers that leads to destruction in the transformer performance. LÄS MER

7. 5. Defect Induced Room-Temperature Ferromagnetism in ZnO and MgO Thin FIlms and Device Development

   Författare :Mukes Kapilashrami; Lyuba Belova; E Dan Dahlberg; KTH; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Room-temperature ferromagnetism; intrinsic defects; un-balanced balanced magnetron sputtering; magnetic anisotropy and photoconductivity; Materials science; Teknisk materialvetenskap;

   Sammanfattning : This thesis presents the discovery of defect induced room-temperature ferromagnetism in industrially important ZnO and MgO thin films, and establishes from a systematic study, in both ZnO and MgO films, the unique phenomenon of the sequences of transitions from ferromagnetism to para-, and eventually the well known diamagnetism of the bulk as a function of film thickness. Highly oriented and high quality dense thin films of ZnO and MgO have been deposited by reactive (balanced) magnetron sputtering under different ambience conditions and deposition temperatures. LÄS MER