Sökning: "power density"
Visar resultat 21 - 25 av 634 avhandlingar innehållade orden power density.
21. Mobile Antenna Systems for 4G and 5G Applications with User Body Interaction
Sammanfattning : 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. LÄS MER
22. Simulation and Characterization of Silicon Carbide Power Bipolar Junction Transistors
Sammanfattning : 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. LÄS MER
23. Low-density parity-check codes : unequal error protection and reduction of clipping effects
Sammanfattning : 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. LÄS MER
24. Characterization and Compensation of Hardware Impairments in Transmitters for Wireless Communications
Sammanfattning : 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. LÄS MER
25. Numerical Optimization of a propeller in a given wake and behind a ship
Sammanfattning : 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. LÄS MER