Šio darbo tikslas – optimizuoti KTU Ultragarso Instituto sukurta ultragarsinės vizualizacijos sistemos modelį. Tam tikslui pasiekti, buvo išanalizuota ultragarsinių vizualizacijos sistemų bei ultragarsinių signalų sklidimo bendri principai bei buvo atlikta modelio naudojamų resursų analizė, kuri parodė, kad buvo neracionaliai išnaudojama operatyvioji atmintis, ko pasiekoje buvo naudojama virtualioji atmintis vietoje operatyviosios. Padarytos programos modelio modifikacijos ne tik pagreitino programos veikimo laiką, bet ir praplėtė skaičiavimo tikslumą iki teorinės begalybės. Skaidymo žingsnio ir modeliavimo tikslumo analizė parodė grafinę priklausomybę, kurios pagalba galima nesunkiai numatyti skaičiavimo laiką norimam tikslumui gauti. / The purpose of that work is to optimize KTU Ultrasonic Institute made supersonic visualization system. On that purpose the main principles of ultrasonic visualization systems and ultrasonic signals propagation were analyzed and the research of the used resources was made. This researched show that the program was using the memory irrationally, that caused usage of the virtual memory instead of Random Access Memory (RAM) which is much slower. Program modification caused increase of the program performance and extended the accuracy of the calculation to the theorycal infinity. The sampling point’s and modeling accuracy’s analysis showed graphical dependence how would it change with the bigger sampling point.

MYRRHA, a Multi-purpose hYbrid Research Reactor for High-tech Applications is currently under development at the Belgian nuclear research center SCK•CEN. It is the first prototype of a nuclear reactor driven by a particle accelerator in the world. Lead-Bismuth Eutectic (LBE) has been selected as spallation neutron source and as primary reactor coolant. Oxygen control strategy has been defined to mitigate undesirable liquid metal corrosion occurring between the steel surface of the main components of MYRRHA and the LBE itself. The development of a reliable oxygen sensor and control device beyond the state-of-the-art for operation in the conditions foreseen in MYRRHA are therefore crucial. A potentiometric oxygen sensor based on the use of yttria partially stabilized zirconia as solid electrolyte combined respectively with air/perovskite oxides, Cu/Cu2O, In/In2O3 or LBE/PbO reference electrode has been developed and operated successfully between 200 and 450 °C in oxygen saturated LBE overcoming the operating temperature limit of previously used Bi/Bi2O3 and air/Pt reference electrode oxygen sensors being of 280 °C and 300 °C approximately.An electrochemical oxygen pump based on the use of yttria partially stabilized zirconia as solid electrolyte and air/Lanthanum Strontium Manganite electrode has been tested both to add and extract oxygen from LBE. The oxygen addition might be limited by the oxygen reduction kinetics at the air/LSM side while, the oxygen extraction is limited at high oxygen potential by the diffusion of oxygen ions through the solid electrolyte and at low oxygen potential by the oxygen diffusion in the liquid LBE. / Doctorat en Sciences / info:eu-repo/semantics/nonPublished

The lead-cooled fast reactor (LFR) is one of the concepts of the Generation IV reactorsystems. There are some issues that have to be solved before a research orcommercial LFR can be built. The objective of this thesis was to identify these keyissues and analyse them by studying results from previous research: choice of fuel,corrosion on structural materials and corrosion/erosion on pumps.The major fuel candidates for the LFR are MOX fuel (Mixed OXide fuel), metallic fuel,nitride fuel and carbide fuel. Nitride fuel has desirable properties but its production ismore difficult than for MOX fuel.Most of today’s commercial steels are not corrosion resistant at higher temperaturesbut they could possibly be used for an LFR test demonstrator with an operatingtemperature lower than 450 ºC. A new type of steel called oxide dispersionstrengthened (ODS) steel and a new ceramic material MAXTHAL both showpromising corrosion resistance even at higher temperatures.By controlling the oxygen concentration a protective oxide film is produced. Flowingliquid coolant causes erosion and wears down the oxide film. Pumps are exposed tocoolant velocities of 10-15 m/s causing both erosion and corrosion. There is nosolution today, but MAXTHAL shows promising results in tests with liquid lead of lowvelocity. There are also other issues unsolved, such as irradiation damage onstructural materials, thus more research is needed.Economic and political aspects were not covered in this study. This thesis work wasperformed at Vattenfall Research and Development AB.

This paper represents the final culmination of a theater senior project. The project consisted of an analytical research paper, performance in a mainstage department production, and supporting process documentation. I portrayed Myrrha, Hunger, Zeus, and others in a production of the play Metamorphoses. Through research on Mary Zimmerman’s 1998 play Metamorphoses, adapted from the works of Roman poet Ovid, this thesis grapples with the historical meaning of the myth of Myrrha. A polarizing figure, Myrrha was cursed to fall in lust with her father. By exploring of portrayals sexual assault onstage, I tackle themes of audience relationships to trauma and taboo subjects. I seek to understand the importance of her story in a modern context, specifically considering the #metoo movement and increasingly public discussions around sexual violence, rape culture, and systematic oppression. I stress our responsibility to understand how codifying stories on stage impacts audiences. This project also contains my conceptualization for the characters I portrayed in Metamorphoses, my rehearsal journal, and post-show reflections. In these sections, I detail the acting theory behind my characters as well as the steps we took to adapt Metamorphoses for our community.

This master’s thesis deals with usage of burn-up (spent) nuclear fuel in nuclear power plants of next generation – accelerator driven transmutation plants which is produced in current nuclear power plants. This system could significantly reduce the volume of dangerous long-lived radioisotopes and moreover they would be able to take advantage of its great energy potential due to fast neutron spectrum. In the introduction are listed basic knowledge and aspects of spent nuclear fuel along with its reprocessing and the possibility of further use while minimizing environmental impact. As another point detailed description of accelerator driven systems is described together with its basic components. In addition this search is followed by individual chronological enumeration of projects of global significance concerning their current development. Emphasis is placed on SAD and MYRRHA projects, which are used like base for calculations. This last, computational part, deals with the creation of the geometry of subcritical transmutation reactor driven by accelerator and subsequent evaluation which assembly is the most effective for transmutation and energy purposes along with changing of target, nuclear fuel and coolant/moderator.