Sökning: "PARTIAL"

Visar resultat 11 - 15 av 2190 avhandlingar innehållade ordet PARTIAL.

1. 11. 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. 12. Measurement and Analysis of Partial Discharges at Semi-Square Voltages

   Författare :Elisabeth Lindell; Chalmers tekniska högskola; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; space charge; Partial discharges PDs ; short rise time; partial discharge measuring techniques; square-like voltages; repetitive voltages; corona;

   Sammanfattning : Insulation is today being exposed to voltages having considerably higher frequency components than the conventional power frequency AC 50 Hz or 60 Hz, for example in motors supplied by adjustable speed drives based on pulse width modulated converters. This has in many cases caused unexpected behaviour of the insulation systems. LÄS MER

4. 13. Modelling of cavity partial discharges at variable applied frequency

   Författare :Cecilia Forssén; Roland Eriksson; Hans Edin; Peter H.F. Morshuis; KTH; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; partial discharges; measurements; modelling; variable frequency; cavities; disc-shaped; polycarbonate; Electric power engineering; Elkraftteknik;

   Sammanfattning : The presence of partial discharges (PD) in high voltage components is generally a sign of defects and degradation in the electrical insulation. To diagnose the condition of high voltage insulation, PD measurements is commonly used. LÄS MER

5. 14. Partial methane oxidation from electronic structure calculations

   Författare :Adam Arvidsson; Chalmers tekniska högskola; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; NATURVETENSKAP; NATURAL SCIENCES; NATURVETENSKAP; NATURAL SCIENCES; TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; NATURVETENSKAP; NATURAL SCIENCES; NATURVETENSKAP; NATURAL SCIENCES; ZSM-5 zeolite; density functional theory; microkinetic modelling; Mo6S8 cluster; partial methane oxidation;

   Sammanfattning : Investigating catalytic reactions with computational methods is a powerful approach to understand fundamental aspects of catalytic reactions and find ways to guide catalytic design. Partial methane oxidation is one example of a reaction with intriguing challenges, where a detailed atomistic approach may help to unravel the bottlenecks of this, as of yet, inefficient reaction. LÄS MER

7. 15. Partial Response and Faster-than-Nyquist Signaling

   Författare :Fredrik Rusek; Institutionen för elektro- och informationsteknik; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Telecommunication engineering; Signalbehandling; Signal processing; Partial Response Signaling; Faster-than-Nyquist Signaling; Digital Communications; Coding Theory; Telekommunikationsteknik;

   Sammanfattning : Bandwidth efficiency is a key objective in the design of a digital communication system. Traditionally it is accomplished by increasing the constellation size of the signaling system. In this thesis alternative techniques are studied. Because the communication channel is continuous, so must the actual time signals be. LÄS MER