Sökning: "Thomas Hammarström"

Visar resultat 1 - 5 av 9 avhandlingar innehållade orden Thomas Hammarström.

1. 1. Detection of Partial Discharges at Fast Rising Voltages

   Författare :Thomas Hammarström; Chalmers tekniska högskola; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Partial discharges; cavities; repetitive voltages; high dV dt.; square like voltages; short rise time; measurements;

   Sammanfattning : The present demand for higher efficiency and flexibility in the energy sector has ledto an increased use of power electronic generated waveforms as these allow energyconversion between different frequencies including DC. The generated waveformsare usually synthesized by so called Pulse Width Modulation (PWM) techniques,where the desired waveform is approximated by a number of square shaped pulseswith a short rise time. LÄS MER

3. 2. Partial Discharges at Fast Rising Voltages

   Författare :Thomas Hammarström; Chalmers tekniska högskola; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; short rise time; cavities; high dV dt.; measurements; Partial discharges; square like voltages; repetitive voltages;

   Sammanfattning : The present demand for higher efficiency and flexibility in the energy sector has led to an increased use of power electronic generated waveforms as these allow energy conversion between different frequencies including DC. The generated waveforms are usually synthesized by so called Pulse Width Modulation (PWM) techniques, where the desired waveform is approximated by a number of square shaped pulses with a short rise time. LÄS MER

4. 3. Violence in the Midst of Peace Negotiations : Cases from Guatemala, Northern Ireland, South Africa and Sri Lanka

   Författare :Kristine Höglund; Thomas Ohlson; Mats Hammarström; Roy Licklider; Uppsala universitet; []
   Nyckelord :SAMHÄLLSVETENSKAP; SOCIAL SCIENCES; Peace and conflict research; conflict resolution; internal conflict; violence; peace process; negotiation; Guatemala; Northern Ireland; South Africa; Sri Lanka; Freds- och konfliktforskning; Peace and conflict research; Freds- och konfliktforskning; Peace and Conflict Research; freds- och konfliktforskning;

   Sammanfattning : Why do peace talks fall apart as a result of violence? The present study addresses the question of why and how violence sometimes changes the dynamics of peace negotiation processes. Incidents of violence may produce friction between and within parties. LÄS MER

5. 4. A Novel Oil-immersed Medium Frequency Transformer for Offshore HVDC Wind Farms

   Författare :Mohammad Kharezy; Per Olof Hedekvist; Yuriu Serdyuk; Thomas Hammarström; Karsten Backhaus; RISE; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; prototype design methodology; finite element analysis; HVDC insulation design; medium frequency transformer; Wind energy; DC-DC power converters;

   Sammanfattning : In this project, a design of an oil type medium frequency transformer for offshore wind farm applications is proposed. The design is intended for applications when series coupling of the output of the DC/DC converters of the wind turbine on their secondary side is done to achieve a cost-effective high voltage solution for collecting energy from offshore wind parks. LÄS MER

7. 5. Poly-and oligothiophenes : Optical probes for multimodal fluorescent assessment of biological processes

   Författare :Karin Magnusson; Peter Nilsson; Per Hammarström; Thomas Borén; Linköpings universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; MEDICIN OCH HÄLSOVETENSKAP; MEDICAL AND HEALTH SCIENCES;

   Sammanfattning : One interesting class of molecules in the research field of imaging biological processes is luminescent conjugated polythiophenes, LCPs. These fluorescent probes have a flexible backbone consisting of repetitive thiophene units. LÄS MER