This thesis examines the influence of inoculation and modification on the internal structure and properties of aluminium-silicon alloys. The effect of inoculation by titanium and boron and modification by sodium and strontium is investigated in experimental part of the thesis. All these metallurgical interventions in the melt are tested on three types of hypoeutectic Al-Si alloys (AlSi10Mg(a), AlSi8Cu3, AlSi7Mg0,3). The experiment was carried out in cooperation with the foundry of non-ferrous metals, Aluminium Group, a.s. in Sloup.

Title: Automation of dust charging experiment Author: Radim Pechal Department: Department of Surface and Plasma Science Supervisor: RNDr. Jiří Pavlů, PhD. Supervisor's e-mail address: Jiri.Pavlu@mff.cuni.cz Abstract: Since the dust grains are expected to cause problems during operation of tokamaks, there is a developing research of these devices which raises interest in dust grain charging processes research as well. Clarification of the dust grain charging processes may help with their solutions. This thesis deals with an issue of designing a part of a new experimental setup for dust grain research built at the Department of Surface and Plasma Science, Charles University in Prague. The base of this experimental setup is original linear quadrupole trap enabling dust grain trapping and its charging by electron, ion, and UV beams. In the thesis, a method of stabilization of one part of grain oscillation frequency detection is described. The thesis is focused on a development of a control unit and high voltage power supply for an image intensifier. To measure charging processes tungsten dust grains were used. This material will be probably used in construction of ITER tomakak. Electron equilibrium characteristics and other parameters were measured. Two samples of tungsten dust grains were used for...

A feed test was carried out on male “Vistar” rats. Four groups of rats, feed with mixtures with 70 % of wheat, differing in grain colour, were compared. For feed trials, near-isogenic lines of derived or recipient varieties of “Novosibirskaya 67” (N67) were selected. These were the N67 grains with white grains, “ANK-28A” with purple grains (Pp1 and Pp2 genes), “ANK-28B” (Pp1 and Pp3) and “Aoi Yu” (unfinished near-isogenic line) with blue aleurone (Ba1 gene). Feed mixtures were standardized to the same nutrient content. The feed trial lasted 72 days. Time increments and biochemical parameters of the blood were evaluated. Statistical differences in glucose (GLU), triglycerol (TG) and total protein (CB) levels were noted in biochemical parameters, with a higher GLU content in N67 and “Aoi Yu”. Higher TG content was recorded in “ANK-28B” and lower in “ANK-28A”. The higher CB content in rat blood was recorded in “Aoi Yu” and lower for all remaining wheat. No statistically significant differences were found in other biochemical parameters of blood (P<0.05). Interestingly, a higher feed consumption per pound was observed in the wheat mix with white grain (N67) and the lowest in “Aoi Yu” with the highest content of anthocyanins. This result is in line with the results of some other authors who have shown a relation between the high anthocyanin content in the feed and the reduced weight additions of laboratory animals.

The aim of this thesis was to compare the influence of agrotechnical measures on yields and certain qualitative parameters of winter wheat as a part of a long-term field experiment, which focuses on agriculture without livestock production at the Field experimental station of Mendel University in Žabčice. The issue was being solved during a period of three years (since 2014/2015 to 2016/2017) in the form of small-plot field experiments. The experiment assessed the influence of the year, soil processing and previous crop on yields, the content of crude proteins and hectolitre weight. The results suggest that the yields and the content of crude proteins are more significantly influenced by the previous crop and the year, rather than by soil tillage. Hectolitre weight was more influenced by the effect of the year.

The present thesis is focused on study of dust grain charging. The experimental part covers interaction between dust grains and high-energy electrons and self-discharging of grains by both field electron emission and field ionization. The second part of the thesis describes construction and evaluation of a linear electrodynamic trap of the novel design. We have observed charging of small dust grains towards high positive electric potentials when bombarded by the high-energy electron beam. We have described an increase of the secondary electron- electron emission yield from negatively charged grains due to the surface field. Further, self-discharging characteristics for both positively and negatively charged grains were measured. The relationship between discharging rate and the rate of the flow of atoms leaving the grain surface due to diffusion was observed for positively charged grains. This suggests significantly lower surface field necessary for ionizing such atoms compared to the ionization of atoms of surrounding gas and compared to the typically published field ionization thresholds. Based on the design published in the master thesis, a linear quadrupole trap of novel design was constructed. Testing measurements confirmed functionality and expected characteristics of the trap. In addition, effects of...

The greatest influence on the grain yield was shown by variants of cultivation. Nitrogen fertilization has reached the highest grain yields, the nitrogen-free fertilizer variant showed average results, and the cetacea subsection showed the lowest yields.

V poslední době je snahou nahradit klasickou komerční olovnatou piezoelektrickou keramiku bezolovnatou, z důvodu zvýšeného zájmu o ochranu životního prostředí a zdraví. Různé typy materiálů již byly navrženy, jako například (K, Na) NbO3 (KNN), (Bi, Na) TiO3 (BNT), (Bi, Na) TiO3 – BaTiO3 (BNT-BT), ale jejich piezoelektrické vlastnosti zatím nedosáhly takových hodnot jako u olovnatý chkeramik (např. olovnatý titanát olova ((Pb Zr)TiO3). Nejvíce se olovnatým materiálů blíží bezolovnatý systém na bázi (1-x)Ba(Zr0.2Ti0.8)O3-x(Ba0.7Ca0.3)TiO3 nebo (Ba, Ca) (Zr, Ti) O3 ((1-x)BZT-xBCT, BCZT) a to díky vysokým piezoelektrickým a dielektrickým parametrům. Nevýhodou tohoto prostředku je jeho velmi vysoká teplota slinování (1520 ° C) za účelem dosažení vysokých piezoelektrických vlastností (např. Piezoelektrické konstanty d33 > 600 pC / N). Tato práce se zabývá bezolovnatou keramikou na bázi BCZT, její výrobou a vylepšením piezoelektrických vlastností dopováním CeO2. Přidáním CeO2 (y wt.%) do (Ba0.85Ca0.15) (Zr0.1Ti0.9) O3 se výrazně snížila slinovací teplota a došlo ke zhutnění při 1350°C. U této kompozice se Curieova teplota pohybovala kolem TC~105°C a velikost zrn byla v rozmezí ~ 10-13 m. Fázový přechod z romboedrické struktury na tetragonální (R-T) byl zjištěn pomocí rentgenové spektroskopie u y = 0 - 0.1 wt.%, což koreluje s výsledky Ramanovy spektrální analýzy. Mikrostrukturní a strukturní charakteristiky byly detailně studovány v korelaci s dielektrickými, feroelektrickými a piezoelektrickými vlastnostmi. Nejlepší funkční vlastnosti byly dosaženy pro keramiku BCZT – 0.07 wt.% CeO2. Tato keramika vykazovala piezoelektrický nábojový koeficient d33 = 507±20pC/N, elektromechanický planární koeficient kp = 51.8 %, dielektrickou konstantu r = 4091±100, ztrátový činitel tan = 0.02, remanentní polarizaci Pr = 13.58C/cm2, intenzitu koercitivního pole EC = 2.13kV/cm při normovaném napětí, d33* nebo Smax/Emax = 840pm/V. Dvoustupňovou kalcinační technikou bylo docíleno homogenního růstu zrn s vysokou relativní hustotou (~ 99% teoretické hustoty). Tato kompozice BCZT- CeO2 vykazovala stálé feroelektrické, dielektrické a piezoelektrické vlastností i při velikosti zrn 10 µm. Bezolovnatá piezoelektrická keramika (Ba0.85Ca0.15-y Cey) (Zr0.1Ti0.9) O3 (BCCeZT) byla dále dopována CeO2 s cílem substituce Ce4+ v místě A krystalické mřížky. Posunutí rentgenových vrcholů k vyšším úhlům naznačuje kontrakce mřížky, což by mohlo způsobit obsazení iontů ceru v místech A této soustavy. Bylo zjištěno, že velikost zrn kolem 10 - 12 m je významná pro vysokou piezoaktivitu bezolovnaté BCCeZT keramiky. Nejvyšší piezoelektrické vlastnosti tato keramika vykazovala při y;Ce = 0.00135 a slinovaná na teplotě 1350°C/4h, kdy piezoelektrické parametry byly d33 = 501±10 pC/N, kp = 38.5±1.92 %, Pr = 12.19 C/cm2, TC = 108.1 °C a s maximální deformací S do 0.14 %. Pro další studium substituce v místě A, byly vyrobeny keramické materiály (Ba1-x-y Cax Cey) (Zr0.1 Ti0.9) O3 (x:Ca = 0.05, 0.10, 0.15, 0.20 a y;Ce = 0.00135). Opět se ukázalo, že pokud byla velikost zrn ~13um, tak keramika vykazovala vysoké piezoelektrické vlastnosti (d33 = 457pC/N) pro x = 0.15 % kalcinované na teplotě 1425 °C. Když se se velikost zrn zvýšila nad 16 um, piezoelektrický nábojový koeficient d33 klesl na 200 pC/N. Rentgenová analýza ukázala změnu fázové struktury z rombické na tetragonální při zvýšení obsahu vápníku.

This master's thesis deals with the effects of the cooling rate on the grain size of magnesium alloys based on Mg–Al (AZ91E) and Mg–Zr–RE (WE43B and Elektron21). The effects of the cooling rate are analyzed on samples of varying thickness for different cooling methods (forced–air–cooling, cooling into polymer, natural air cooling). We also evaluated the final microstructure, porosity, hardness, and mechanical properties for investment castings. Based on the evaluated grain sizes, we demonstrated a significant difference in the cooling rate influence on the grain size for the alloy AZ91E. Compared to Zirconium-based alloys (WE43B and Elektron21), for which the zirconium content influences grain size the most. For the alloys based on Mg–Zr–RE, it is possible to prefer casting conditions, without negative enlarging of the grain size.

This thesis looks at the comparison between grain micromorphology of moraines, debris flows and similar accumulations. Moraine samples were taken in the Černé jezero Lake area, Bohemian Forest, in the Velická dolina Valley, High Tatras, and in the Labský důl Valley, Krkonoše Mts. Samples of debris flows and unverified accumulations were taken in the Důl Bílého Labe Valley, Krkonoše Mts., and further samples of accumulations were obtained from the valley of Prudký potok Stream, Králický Sněžník Mts., the valley of Vražedný potok Stream and Velká Kotlina, Hrubý Jeseník Mts. Sediments were examined under electron microscope and their morphological characteristics and influence of the environment were identified and described. Calculated exoscopic moraine standard was used for comparison of examined forms of relief using distance coefficients, statistical analysis were carried out which identified diagnostic characters for distinguishing moraines and debris flows. There was also calculated exoscopic standard for different types of moraines (frontal, lateral, basal). This research highlighted the differences between moraines and debris flows, and between different types of moraines. The study also proved that typical glacial microtextures, that are generally accepted, occur at similar levels on grains...

Agriculture is, after fossil fuels, the second largest producer of greenhouse gas emissions, which are responsible for global climate change, and it is necessary to look for ways to reduce this environmental load. Cereals are the most cultivated crops in the world, so it is appropriate to examine their share of this load. The aim of the thesis was to evaluate and compare the environmental aspects of the cultivation of selected cereals (wheat, rye and barley) in the conventional and ecological farming system. The resulting environmental load was first calculated on 1 kg of grain, and then the load was recalculated to a load of 1 kg of protein contained in grain of selected cereals. Protein content in grain is one of the grain quality indicators. A simplified LCA method has been used for the environmental load calculations. This method is used for environmental impact assessments and covers the whole life cycle of the product.