Search results for "GST"
showing 10 items of 874 documents
Izglītības iespējas Latvijas Universitātes filiālēs un absolventu nodarbinātība Latvijas reģionos
2019
Sanita Ģērmane. Bakalaura darbs. Izglītības iespējas Latvijas Universitātes filiālēs un absolventu nodarbinātība Latvijas reģionos. – Rīga: Latvijas Universitāte, 2019. Bakalaura darba apjoms 68 lappuses. Bakalaura darbs sastāv no Ievada, teorētiskās analīzes, situācijas izpētes daļas, pētījuma rezultātu daļas, secinājumu un priekšlikumu daļas, kā arī no izmantotās literatūras un avotu saraksta. Darbs satur 10 tabulas, 15 attēlus, 43 izmantotās literatūras un informācijas avotus un 1 pielikumu. Pētījuma aktualitāte: Latvijas reģionu kopējās attīstības kontekstā arvien vairāk tiek aktualizēts jautājums par Latvijas reģionu attīstību un ekonomisko izaugsmi tajos. Augstāko izglītības iestāžu u…
Hlorēto parafīnu un bromēto antipirēnu noteikšana apkārtējās vides paraugos no Svalbāras, izmantojot augstas izšķirtspējas masspektrometriju
2022
Maģistra darbā ir apkopota informācija bromēto antipirēnu un hlorēto parafīnu izmantošanas vēsturi, īpašībām un izplatības dinamiku līdz polāriem reģioniem, ar fokusu uz heksabromciklododkānu. Papildus, tika apkopota informācijā no literatūras par šo savienojumu sastopamību apkārtējās vides paraugos no Arktikas un Antarktīdas. Iepriekš izstrādāta paraugu sagatavošanas metode eksperimentālā daļā tika optimizēta, izvērtējot izvēlēto fāžu efektivitāti bromēto antipirēnu frakcionēšanai. Paraugu sagatavošanas procedūru pielietoja paraugos esošu piesārņotāju profilu raksturošanai un daudzumu noteikšanai Eiropas Arktikas izcelsmes augsnes paraugos.
Tritium retention in plasma facing materials of JET ITER-Like-Wall retrieved from the vacuum vessel in 2012 (ILW1), 2014 (ILW2) and 2016 (ILW3)
2021
Abstract ITER-Like-Wall (ILW) project has been carried out at Joint European Torus (JET) to test plasma facing materials relevant to International Thermonuclear Experimental Reactor – ITER [1]. Limiters and an upper dump plate of the vacuum vessel are made of bulk beryllium tiles, whereas for the divertor bulk tungsten and tungsten-coated carbon fibre (CFC) composite tiles are used. During the shutdowns in ILW1 (2012), ILW2 (2014) and ILW3 (2016), selected beryllium tiles were removed from the vacuum vessel. In this study, tiles from three positions were analysed, and analysis results were compared regarding both the tile position in the vacuum vessel and differences in the exploitation con…
Untersuchung der Feldelektronenemission und ihrer Temperaturabh�ngigkeit bei Stromst�rken zwischen 10?14 und 10?19 A
1964
The field emission of a tungsten point cathode at very low emission currents was investigated by means of a secondary emission multiplier. The validity of the Fowler-Nordheim equation was experimentally confirmed within the range from 10−8 to 10−19 A. The dependence of the total emission current on temperature and electrical field strength was measured in the transition region between thermionic and field emission. A comparison is drawn with the theory ofMurphy andGood.
Quantitative analysis of rhenium in irradiated tungsten
2021
Abstract Pure tungsten (W), irradiated to 3.5 dpa in a target of the Swiss neutron spallation source (SINQ), was characterized using high-sensitivity HPGe gamma ray spectroscopy to identify the present radionuclides. Synchrotron X-ray absorption spectroscopy was used to quantify the amount of Re produced in the irradiated W. An atomic concentration of 0.61% Re in the irradiated W was determined from the height of the L3-edge X-ray absorption edge jump. Analysis of the local atomic structure from the extended X-ray absorption fine structure (EXAFS) spectra indicates that rhenium (Re) produced in the system is mainly coordinated by W atoms and partly coordinated by void defects. First-princip…
Overview of the JET results with the ITER-like wall
2013
Following the completion in May 2011 of the shutdown for the installation of the beryllium wall and the tungsten divertor, the first set of JET campaigns have addressed the investigation of the retention properties and the development of operational scenarios with the new plasma-facing materials. The large reduction in the carbon content (more than a factor ten) led to a much lower Zeff (1.2-1.4) during L- and H-mode plasmas, and radiation during the burn-through phase of the plasma initiation with the consequence that breakdown failures are almost absent. Gas balance experiments have shown that the fuel retention rate with the new wall is substantially reduced with respect to the C wall. T…
Trapping of hydrogen and helium at dislocations in tungsten: anab initiostudy
2017
Retention of plasma gas components such as hydrogen (H) isotopes and helium (He) is one of the limiting factors in selection of plasma facing materials for future thermonuclear fusion devices. Tungsten (W) is one of the promising candidates for such materials and was chosen for the divertor armor for International Thermonuclear Experimental Reactor (ITER) and the first wall material for the design of the demonstrational fusion power plant - DEMO. For the analytical estimation of accumulation of H/He components in tungsten, it is important to understand the relevant physical mechanisms of their trapping in the material and thoroughly parameterize them numerically. Experiments involving high …
Study of Low Work Function Materials for Hot Cavity Resonance Ionization Laser Ion Sources
2008
The selectivity of a hot cavity resonance ionization laser ion source (RILIS) is most often limited by contributions from competing surface ionization on the hot walls of the ionization cavity. In this article we present investigations on the properties of designated high-temperature, low-work function materials regarding their performance and suitability as cavity material for RILIS. Tungsten test cavities, impregnated with a mixture of barium oxide and strontium oxide (BaOSrO on W), or alternatively gadolinium hexaboride (GdB6) were studied in comparison to a standard tungsten RILIS cavity as being routinely used for hot cavity laser ionization at ISOLDE. Measurement campaigns took place …
Search for very long-lived isomers in the hafnium-tungsten region
2000
Targets of ${}^{48}\mathrm{Ca}$ have been bombarded with ${}^{134,136}\mathrm{Xe}$ beams as part of a search for long-lived, high-K states in well-deformed nuclei with $A\ensuremath{\approx}180.$ Several known isomers were observed by off-line \ensuremath{\gamma}-ray detection, and limits have been established for high-K isomer production in various isotopes of hafnium $(A=175--178),$ tantalum $(A=177--181),$ and tungsten $(A=177--181).$
Ģimenes hiperholesterinēmijas prevalence starp pacientiem ar koronāro artēriju aterosklerozi
2018
Ievads: Tiek uzskatīts, ka vienam no 200-250 cilvēkiem ir heterozigota ģimenes hiperholesterinēmija (ĢH). Pacientiem ar ĢH ir ievērojami paaugstināts zema blīvuma lipoproteīna holesterīna (ZBLH) līmenis, kas savukārt noved pie agrīnas aterosklerozes attīstības. Aterosklerozei attīstoties koronārajās artērijās, pieaug mirstība no koronārās sirds slimības. Pacientiem ar ĢH ZBLH līmenis tipiski ir >5 mmol/l, taču lipīdus pazeminošās terapijas fonā, tas var samazināties zem 5 mmol/l, kas apgrūtina ĢH diagnozes atpazīšanu. Mērķis: Noskaidrot potenciālo ģimenes hiperholesterinēmijas izplatību starp Latvijas Kardioloģijas centrā (LKC) stacionētiem pacientiem ar pierādītu koronāro artēriju ateroskl…