Search for dissertations about: "spectral edge frequency"

Showing result 1 - 5 of 15 swedish dissertations containing the words spectral edge frequency.

2. 1. Investigation of Tonal Noise Sources from Centrifugal Fan using Detached Eddy Simulation

   Author : Martin Ottersten; Chalmers tekniska högskola; []
   Keywords : TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Computational aeroacoustics; Blade passing frequency; Centrifugal fan; Low-frequency rotation; Tonal noise.;

   Abstract : Since we spend the majority of our time indoors, heating, ventilation, and air conditioning (HVAC) systems have become a more and more important part of many people´s life. They provide a sufficient amount of airflow with the correct temperature, quality, and humidity. READ MORE

4. 2. CALLUM Linear Transmitter - Architecture and Circuit Analysis

   Author : Roland Strandberg; Institutionen för elektro- och informationsteknik; []
   Keywords : TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Telekommunikationsteknik; Telecommunication engineering; loop time delay; modulation negative feedback; spectral emissions; baseband model; CALLUM; Linear transmitter architecture; power amplifier linearization;

   Abstract : This doctoral dissertation presents a study of linear radio transmitters based on the combined analog locked loop universal modulator (CALLUM) approach. Linear architectures such as CALLUM are very attractive for power-efficient operations, since they have no fundamental limitations prohibiting a 100% efficiency for all envelope levels, without sacrificing the potential of a linear transmission. READ MORE

5. 3. Downlink Resource Allocation in Cooperative Wireless Networks

   Author : Jingya Li; Chalmers tekniska högskola; []
   Keywords : TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; precoding design; load balancing; relaying; imperfect channel state information; imperfect synchronization; Coordinated multi-point transmission; I Q imbalance; resource allocation; fractional frequency reuse;

   Abstract : Wireless cooperative networks, which is based on exploiting coordination among multiple access nodes, has been considered as a promising approach to improve the spectral efficiency, reduce the energy consumption, and extend the network coverage of future wireless communication systems. In practice, the actual benefit of multi-node cooperation is affected by a variety of factors, including the quality of channel state information (CSI), the constraints on the feedback and backhaul links, hardware impairments, resource allocation and data processing schemes. READ MORE

6. 4. Broadband and HF Radiation from Cloud Flashes and Narrow Bipolar Pulses

   Author : Noor Azlinda Ahmad; Vernon Cooray; Farhad Rachidi; Uppsala universitet; []
   Keywords : NATURVETENSKAP; NATURAL SCIENCES; Lightning; Cloud Flashes; Narrow Bipolar Pulses; HF radiation; Other physics; Övrig fysik; Engineering Science with specialization in Atmospheric Discharges; Teknisk fysik med inriktning mot atmosfäriska urladdningar;

   Abstract : Remote measurement of electric field generated by lightning has played a major role in understanding the lightning phenomenon. Even though other measurements such as photographic and channel base current have contributed to this research field, due to practical reasons remote measurements of electric field is considered as the most useful tool in lightning research. READ MORE

7. 5. Direct numerical simulations of the rotating-disk boundary-layer flow

   Author : Ellinor Appelquist; Philipp Schlatter; Henrik Alfredsson; Rebecca Lingwood; Christopher Davies; KTH; []
   Keywords : Fluid mechanics; boundary layer; rotating disk; laminar-turbulent transition; convective instability; absolute instability; secondary instability; crossflow instability; direct numerical simulations; Teknisk mekanik; Engineering Mechanics;

   Abstract : This thesis deals with the instabilities of the incompressible boundary-layer flow that is induced by a disk rotating in otherwise still fluid. The results presented are mostly limited to linear instabilities derived from direct numerical simulations (DNS) but with the objective that further work will focus on the nonlinear regime, providing greater insights into the transition route to turbulence. READ MORE