Conventional and nonconventional Kramers-Kronig analysis in optical spectroscopy

This Master’s Thesis is dedicated to the investigation and testing conventional and nonconventional Kramers-Kronig relations on simulated and experimentally measured spectra. It is done for both linear and nonlinear optical spectral data. Big part of attention is paid to the new method of obtaining complex refractive index from a transmittance spectrum without direct information of the sample thickness. The latter method is coupled with terahertz tome-domain spectroscopy and Kramers-Kronig analysis applied for testing the validity of complex refractive index. In this research precision of data inversion is evaluated by root-mean square error. Testing of methods is made over different spectral range and implementation of this methods in future is considered.

Spectral characteristics of bacteriorhodopsin water solution

The object of the study is bacteriorhodopsin. This light-sensitive protein have been selected as perspective substance for optical and optoelectronic applications. Bacteriorhodopsin carries out pumping protons through the cell membrane. Biomolecule converts light into an electric signal when sandwiched between electrodes. These properties were utilized in this research to implement photosensors on the basis of BR layers. These properties were utilized in this research to the bR water solution. According to the absorption spectra and using Kramers – Kronig relation the extinction coefficient has been calculated, as well as the related change of the refractive index value.

Analysis of heat transfer coefficient in silica nanofluids with water as base fluid under transitional flow

The effect of Reynolds number variation in a vertical double pipe counterflow heat exchanger due to the changes in viscosity can cause the change in flow regime, for instance, when heats up and cools down, it can convert from turbulent to laminar or inversely, that can have significant effect on heat transfer coefficient and pressure drop. Mainly, the range of transition phase has been studied in this study with the investigation of silica nanofluid dispersed in water in three different concentrations. The results have been compared with distilled water sample and showed a remarkable raise in heat transfer coefficient while pressure drop has been increased respectively, as well. Although pumping power has to go up at the same time and it is a drawback, heat transfer efficiency grows for diluted samples. On the other hand, for the most concentrated sample, effect of pressure drop dominates which leads to decline in the overall efficiency.