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Visar resultat 1 - 5 av 24 avhandlingar som matchar ovanstående sökkriterier.

1. 1. Developing semi-empirical ab initio based potentials in materials modeling

   Författare :Jie Fu; Anatoly Belonoshko; Michael Odelius; KTH; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Fysik; Physics;

   Sammanfattning : Ab initiocalculation based on density function theory (DFT) is an accu-rate and efficient method for modelling material properties. It is performedby solving the Shrödinger equations with a few assumptions to obtain thephysical properties of the system. It is very computational demanding whendealing with large systems or long-time simulations. LÄS MER

3. 2. Modeling of a Retrodirective Channel With Active Antenna Arrays for Cross-Eye Jamming

   Författare :Björn Petersson; Martin Norgren; Warren P. du Plessis; KTH; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; electronic warfare; antenna array; antenna system; radar countermeasures; jamming; cross-eye; systems modeling; system performance; systems simulation; Electrical Engineering; Elektro- och systemteknik;

   Sammanfattning : Cross-Eye (CE) jamming is a technique aimed at inducing false target angles in radar measurements. The potential to deceive monopulse radar, a radar type commonly used due to its angular accuracy and resilience against jamming, has captured the interest of Electronic Warfare (EW) system manufacturers. LÄS MER

4. 3. Enhanced Dielectric Response Methods for the Characterization of Dielectric Materials

   Författare :Jing Hao; Nathaniel Taylor; KTH; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; FDS; non-contact; dielectric response; combined AC and DC; space-charge polarization;

   Sammanfattning : Dielectric response measurement is widely used for condition assessment of high voltage equipment and for characterizing candidate materials. Measurement with high accuracy and reliability is important in all stages of the lifetime of high voltage equipment, from manufacture to replacement decision. LÄS MER

5. 4. On reliability modelling of ageing equipment in electric power systems with regard to the effect of maintenance

   Författare :Tommie Lindquist; Prof. Roland Eriksson; Dr. Lina Bertling; Docent Carl-Ejnar Sölver; KTH; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Electrical power technology; Maintenance; reliability modelling; electrical power systems; ageing; failure mechanisms; Elkraftteknik; Electric power engineering; Elkraftteknik;

   Sammanfattning : Power system maintenance optimisation involves obtaining the minimum total costs, including preventive and corrective maintenance costs and the cost of failures for both supplier and customer. To calculate the cost of failure, information is needed about the equipment reliability characteristics. LÄS MER

7. 5. High Frequency Model of Electrified Railway Propulsion System for EMC Analysis

   Författare :Kelin Jia; Rajeev Thottappillil; Hans Bängtsson; KTH; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Electromagnetic compatibility; railway; propulsion system; multitransmission line; ac motor modeling; vector fitting; fast transient;

   Sammanfattning : A model of the electrified railway propulsion system working in a wide frequency range is studied in this thesis. The high frequency modeling is the first stage to study and predict the Electromagnetic compatibility (EMC) problems in the electrified railway propulsion system, which are safety and reliability issues of high concern. LÄS MER