Search for dissertations about: "power density"

Showing result 21 - 25 of 631 swedish dissertations containing the words power density.

2. 21. Mobile Antenna Systems for 4G and 5G Applications with User Body Interaction

   Author : Kun Zhao; Sailing He; Cyril Luxey; KTH; []
   Keywords : TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Antenna; MIMO; mmWave; Mobile communication; SAR; Power density; User body effect; Channel modeling; Multiplex efficiency; Electrical Engineering; Elektro- och systemteknik;

   Abstract : In the thesis, the user body effect on antennas in a mobile terminal is discussed. In order to overcome the degradation of Multiple-Input Multiple-Output (MIMO) performance due to the user body effect, a quad-elements MIMO antenna array which can mitigate the body effect through an adaptive antenna switching method is introduced for 4G mobile terminals. READ MORE

4. 22. Simulation and Characterization of Silicon Carbide Power Bipolar Junction Transistors

   Author : Benedetto Buono; Mikael Östling; Gunnar Malm; Martin Domeij; Lothar Frey; KTH; []
   Keywords : TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; silicon carbide; power device; BJT; diode; simulation; characterization; current gain; on-resistance; breakdown voltage; forward voltage drop; degradation; SRA - ICT; SRA - Informations- och kommunikationsteknik;

   Abstract : The superior characteristics of silicon carbide, compared with silicon, have suggested considering this material for the next generation of power semiconductor devices. Among the different power switches, the bipolar junction transistor (BJT) can provide a very low forward voltage drop, a high current capability and a fast switching speed. READ MORE

5. 23. Low-density parity-check codes : unequal error protection and reduction of clipping effects

   Author : Sara Sandberg; David Declercq; Luleå tekniska universitet; []
   Keywords : TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Signalbehandling; Signal Processing;

   Abstract : The invention of low-density parity-check (LDPC) codes made reliable communication possible at transmission rates very close to the theoretical limit predicted by Shannon. However, communication close to the Shannon limit requires very long codes and results in long delay and high encoder and decoder complexity. READ MORE

6. 24. Characterization and Compensation of Hardware Impairments in Transmitters for Wireless Communications

   Author : Zain Ahmed Khan; Peter Händel; Magnus Isaksson; Mikko Valkama; KTH; []
   Keywords : TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Power amplifier; RF transmitters; SISO; MIMO; crosstalk; Volterra series; Volterra kernels; behavioral modeling; DPD; Ramanujan sums; multitone signals; I Q Imbalance; non-linearity; memory polynomial; density estimation; hardware impairments; Electrical Engineering; Elektro- och systemteknik;

   Abstract : Increasing demands for data rate, energy efficiency and reliability in wireless communications have resulted in the introduction of radio frequency (RF) multiple input multiple output (MIMO) transmitters. However, MIMO transmitters suffer from additional crosstalk impairments along with the power amplifier (PA) and I/Q imbalance distortions observed in single input single output (SISO) transmitters. READ MORE

7. 25. Numerical Optimization of a propeller in a given wake and behind a ship

   Author : Kaijia Han; Chalmers tekniska högskola; []
   Keywords : TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; propeller geometry; pressure fluctuation; correction; full scale; efficiency; RANS; cavitation; grid density; verification; delivered power; optimization; Hamburg test case; iteration number;

   Abstract : The work presented in this thesis includes two stages in a research project at the Rolls-Royce University Technology Center (UTC) at Chalmers Technology University. The objective of the project is to develop an optimization technique for ship/propeller interaction. READ MORE