Search for dissertations about: "Periodic conditions"

Showing result 11 - 15 of 173 swedish dissertations containing the words Periodic conditions.

2. 11. Interaction of CO and methane with platinum, Low-temperature oxidation and sensor response mechanisms

   Author : Elin Becker; Chalmers tekniska högskola; []
   Keywords : TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; CO; Low-temperature activity; XAS; In situ spectroscopy; Environmental catalysis; Support material; Periodic operation; XANES; Chemical sensors;

   Abstract : The aim of this thesis project was to increase the understanding of the mechanisms for low-temperature oxidation of carbon monoxide and methane over supported platinum catalysts. In situ spectroscopic methods together with mass spectrometry were used to study the catalysts during both steady state and transient conditions. READ MORE

4. 12. Numerical Studies of Energy Gaps in Photonic Crystals

   Author : Andreas Rung; Carl-Gustaf Ribbing; Norbert Kaiser; Uppsala universitet; []
   Keywords : TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Materials science; photonic crystals; polaritonic; periodic structures; Reststrahlen; band structure; energy gap; Materialvetenskap; Materials science; Teknisk materialvetenskap;

   Abstract : The concept of photonic crystals was born in the late 1980's when two important letters were published that showed the possibility to control light propagation by a periodic structure. A photonic crystals consists of two or more materials with different dielectric functions periodically arranged on the length scale of light. READ MORE

5. 13. Miniaturized Hard Waveguides in Multifunction Array Antennas

   Author : Malcolm Ng Mou Kehn; Chalmers tekniska högskola; []
   Keywords : TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; interlaced arrays; Floquet theorem; reflector antennas; focal plane array; multifunction antennas; miniaturized waveguides; multilayer structures; spectral domain technique; periodic structures; aperture reuse; method of moments; soft and hard surfaces; array antennas;

   Abstract : Recent advances in technologies of wireless communications systems have led to an increasing desire for several antennas performing diverse functions at different frequencies to be integrated into a common radiating aperture. This gives rise to the so-called multifunction antenna, which affords the saving of scarce premium real estate and can alleviate problems arising from excessive antenna protrusions in aspects such as aerodynamics, aesthetics, and stealth capability in military applications. READ MORE

6. 14. Wind-turbine wake flows - Effects of boundary layers and periodic disturbances

   Author : Ylva Odemark; Jens Fransson; Per-Åge Krogstad; KTH; []
   Keywords : TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; wind power; wind-turbine model; wind tunnel; porous disc; hot-wire anemometry; particle image velocimetry; blade element momentum method; large eddy simulations; actuator disc method;

   Abstract : The increased fatigue loads and decreased power output of a wind turbine placed in the wake of another turbine is a well-known problem when building new wind-power farms and a subject of intensive research. These problems are caused by the velocity gradients and high turbulence levels present in the wake of a turbine. READ MORE

7. 15. Higher order differential operators on graphs

   Author : Jacob Muller; Pavel Kurasov; Ram Band; Stockholms universitet; []
   Keywords : NATURVETENSKAP; NATURAL SCIENCES; Almost periodic functions; differential operators on metric graphs; quantum graphs; estimation of eigenvalues;

   Abstract : This thesis consists of two papers, enumerated by Roman numerals. The main focus is on the spectral theory of -Laplacians. Here, an -Laplacian, for integer , refers to a metric graph equipped with a differential operator whose differential expression is the -th derivative. READ MORE