Determination of Joule-Thompson factor

Report gives the comprehensive information about the calculation of the fundamental physical property of gases and liquids Joule-Thompson effect. The Joule-Thompson effect deals with the behaviour of fluids flowing through a jet. A knowledge about this property is used in the exploration practice in the area of separation of crude oil and natural gas

Preparation and characterization of highly thulium- and alumina-doped optical fibers for single-frequency fiber lasers

Thulium-doped fibers suitable for core-pumped single-frequency lasers were fabricated by the modified chemical vapor deposition (MCVD) method. Refractive index profile, doping profile and spectral absorption was measured. High doping concentration of thulium ions should be achieved to allow for high absorption of light at a pump wavelength while the thulium ions clustering should be avoided to prevent the cooperative upconversion and quenching processes. The fabricated fibers featured pump absorption up to 70dB/m at a pump wavelength of 1611nm. The single-frequency master oscillator with a resonator composed of a pair of fiber Bragg gratings and a thulium-doped fiber was demonstrated with predominantly single ended operation. We achieved a slope efficiency of 22% and a threshold of 22mW at a lasing wavelength of 1944nm

Perception of ski infrastructure in ORP Liberec by inhabitants of city Liberec

katedra: KGE; přílohy: CD; rozsah: 51 s.Subject of this bachelor or thesis was make a research dedicated to location, availability and preference of ski facilities in Liberec district, also preparation and execution of research on perception of skiing infrastructure in Liberec district compared to others ski resorts. The aim was to develop mental maps and evaluate research results on perception in terms of preference and evaluate ski areas from the perspective of the Liberec city residents.Předmětem této bakalářské práce bylo provést výzkum rozmístění, dostupnosti a preference lyžařských zařízení v ORP Liberec a příprava a realizace výzkumu percepce lyžařské infrastruktury v ORP Liberec v porovnání s jinými lyžařskými areály. Cílem bylo vypracování mentálních map a zhodnocení výsledků výzkumu percepce z hlediska preference a evaluace lyžařských areálů z pohledu obyvatel města Liberec

Estimation of quality for steel wire ropes according

Life and work dependability of steel wire ropes depend also on their quality. Test results of the steel wire ropes for pull, bend and torque are used for determination of their work capacity by safety factors and standards. To estimate the quality of steel wire ropes a factor of unequal pull steel wires, which we evaluated for sixty nine operating steel wire ropes made in various countries, can be calculated. The tests revealed that producers of steel wire ropes use for their products steel wires with unequal properties, so that results of the calculation is more disperse especially for bend and torque. Our results this type of steel wire ropes to have no guarantee of long life in comparison with present standards

PASSIVELY Q-SWITCHED YTTERBIUM AND CHROMIUM ALL-FIBRE LASER

A chromium-doped saturable absorber fibre stabilizes an otherwise spontaneously chaotic ytterbium- doped fibre laser. This original passively Q-switched all-fibre laser produces sustained and stable trains of smooth pulses at high repetition rate

Self-induced laser line sweeping in double-clad Yb-doped fiber-ring lasers

International audienceExperimental observation of the self-induced laser line sweeping (SLLS) in fiber ring lasers is presented. The SLLS with the same gain fiber is studied in Fabry-Perot cavity for comparison. The SLLS effect manifests itself as a laser wavelength drift with speed of the order of nanometer per second from shorter to longer wavelengths across several nanometers and fast backward jump. Recently, the dynamics of the SLLS in a Fabry-Perot cavity fiber laser was qualitatively described by a dynamic grating induced by spatial-hole-burning in the ytterbium doped fiber where the lifetime of the grating was related to the self-sustained relaxation oscillations. In this paper we address possible discrepancies between the published theoretical model and earlier observations of SLLS, particularly in fiber-ring lasers.We show that the qualitative theoretical model developed for explaining SLLS in the Fabry-Perot cavity can be used also to explain the SLLS effect we observed earlier in fiber-ring lasers