Search results for "Material Physics"
showing 9 items of 9 documents
Deformative Properties of Monotropic Plastic Foams with a Pronounced Strut-Like Strukture
1996
Disertācija angļu valodā, kopsavilkums arī latviešu un vācu valodā.
Optical properties of plasma electrolytic oxidation coatings on aluminium alloy surface
2021
Plazmas elektrolītiskā oksidēšana (PEO) ir process biezu (daži desmiti mikronu), cietu un ķīmiski izturīgu oksīdu pārklājumu veidošanai uz metāla virsmām. Šajā darbā pētīti PEO pārklājumu dažādi luminiscences īpašību aspekti. Pētītas gan pārklājumu iegūšanas procesa modificēšanas iespējas, gan iegūto pārklājumu praktiskie pielietojumi, īpašu uzmanību pievēršot korelācijai starp sintēzes parametriem un pārklājumu optiskajām īpašībām. Šajā pētījumā apskatītas trīs galvenās tēmas: 1) PEO pārklājumu aktivēšana ar piejaukumiem to luminiscences īpašību pētīšanai; 2) pārklājumu izgatavošana ar dozimetra īpašībām un to pielietojamības novērtēšana; 3) aktivēta stroncija alumināta kompleksā oksīda si…
Electronic excitations and processes in long lasting luminescence material SrAl2O4
2019
Persistent luminescent material SrAl2O4: Eu2+, Dy3+ is widely used and studied for energy efficient applications. A study of SrAl2O4:Eu,Dy; SrAl2O4:Dy, and undoped SrAl2O4 material was conducted. Improvements for the mechanism of persistent luminescence have been suggested, that involve tunnelling of electron from trapping center to Eu3+, and the proof for stable Dy4+ existence in strontium aluminate has been presented. Undoped material luminescence has been observed, consisting of trace impurity and intrinsic defects luminescence. The results of this work give new knowledge and improve the existing concepts of persistent luminescence in Eu activated strontium aluminates. They also open som…
The Jyväskylä Accelerator Laboratory
2014
The Jyvaskyla Accelerator Laboratory is a national center for nuclear and accelerator-based research and education. It is an integral part of the Department of Physics, University of Jyvaskyla. The Accelerator Laboratory and the Department Physics were moved to the current site in the early 1990s, as described in the previous Laboratory Portrait published in 1991 [1]. Since then the research program of the laboratory has been structured around the main instruments and research fields, which share the available beam time. The present laboratory layout is shown in Figure 1. In addition to basic research in nuclear and accelerator based materials physics, beam time is reserved for commercial s…
CERN's longest serving experimental facility
2004
The On-Line Isotope Separator ISOLDE has operated continuously at CERN since 1967. Today ISOLDE and its Post accelerator REX-ISOLDE, dedicated to the production of a large variety of radioactive ion beams with energies from 1 keV/u up to 3.1 MeV/u, are used for a great number of different experiments in the fields of nuclear and atomic physics, nuclear astrophysics, material physics and life sciences. The facility, originally located at the CERNs first accelerator Synchrocyclotron (SC), has been located at the Proton-Synchrotron Booster (PSB) since 1992. Long and outstanding operation of ISOLDE has had important impact on the evolution of nuclear physics and its applications. ISOLDE has bee…
A particle based simulation model for glacier dynamics
2013
This publication is contribution number 22 of the Nordic Centre of Excellence SVALI, “Stability and Variations of Arctic Land Ice”, funded by the Nordic Top-level Research Initiative (TRI). The work has been supported by the SVALI project through the University of Lapland, Arctic Centre, and through the University Centre in Svalbard. Funding was also provided by the Conoco-Phillips and Lunding High North Research Program (CRIOS: Calving Rates and Impact on Society). A particle-based computer simulation model was developed for investigating the dynamics of glaciers. In the model, large ice bodies are made of discrete elastic particles which are bound together by massless elastic beams. These…
Modeling friction between shearing brittle surfaces with a discrete element method
2018
Hauraiden materiaalien murtuminen on eräs materiaalifysiikan peruskysymyksistä. Sille ei ole vieläkään olemassa täydellistä teoreettista selitystä, joten ennusteiden tekeminen nojaa vahvasti kokeisiin ja niihin perustuviin numeerisiin malleihin. Tässä työssä suunnittelemme ja toteutamme diskreettielementtimenetelmän sellaisen fysikaalisen systeemin tutkimiseen, jossa kaksi haurasta pintaa leikkaavat toisiaan. Keskitymme erityisesti siihen kuinka erilaiset voimamallit sisäiselle kitkalle vaikuttavat materiaalin ulkoiseen kitkaan. Käyttämällä graniittia koemateriaalina huomaamme, että sen ulkoinen kitka riippuu voimakkaasti sen sisäisestä kitkasta, kun ulkoinen paine on lähellä materiaalin pu…
Numerical studies of transport in complex many-particle systems far from equilibrium
2012
In this Thesis, transport in complex nonequilibrium many-particle systems is studied using numerical master equation approach and Monte Carlo simulations. We focus on the transport of the center-of-mass of deformable objects with internal structure. Two physical systems are studied in detail: linear polymers using the Rubinstein-Duke model and single-layer metal-on-metal atomic islands using a semi-empirical lattice model. Polymers and islands are driven out of thermodynamic equilibrium by strong static and time-dependent external forces. Topics covered in this work include introductions to nonequilibrium statistical mechanics, master equations and computational methods, with construction a…
Development of niobium-based superconducting junctions
2012
This thesis presents a review of publications which mainly focuses on the fabrication and performance of Nb-based normal metal-insulator-superconductor (NIS) tunnel junctions and superconductor-normal metal-superconductor (SNS) Josephson junctions at low temperatures. The Cu/AlOx-Al/Nb based NIS double tunnel junctions were successfully fabricated using conventional electron beam lithography combined with multi-angle thermal evaporation of metals in ultra high vacuum. The subgap characteristics of these junctions showed expected temperature dependence from 0.2 K to 5 K with a good thermometry sensitivity 0.2-0.3 mV/K. Signatures of small electronic cooling effects were observed near the Nb …