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Charest, Julien. "Mécanismes cellulaires et moléculaires régulés par SLITRK2 et SLITRK5 dans la formation des circuits dopaminergiques du mésencéphale." Master's thesis, Université Laval, 2016. http://hdl.handle.net/20.500.11794/27551.
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Les neurones dopaminergiques du mésencéphale (mDA) sont impliqués dans une variété de fonctions clefs du système nerveux central, incluant le mouvement volontaire, les processus affectifs, la récompense, l’attention, la mémoire de travail et l’apprentissage. La spécification des neurones mDA, de même que l’établissement des circuits dopaminergiques, sont finement régulés au cours du développement et requièrent l’activation spatiotemporelle complexe de facteurs de transcription et de leurs gènes cibles. La dégénérescence ou une perturbation de l’activité des neurones mDA peut mener au développement de troubles neurodégénératifs ou neuropsychiatriques graves, tels la maladie de Parkinson (PD), la schizophrénie (SCZ) et les troubles du spectre obsessif compulsif (OCD). Les facteurs de transcriptions Lmx1a et Lmx1b sont des déterminants précoces de la destinée dopaminergique, essentiels à la différenciation et à la spécification des neurones mDA. Des polymorphismes de LMX1A/B ont précédemment été associés à la SCZ et aux troubles du spectre OCD. Parmi les gènes développementaux sous le contrôle transcriptionnel de Lmx1a/b, nous avons identifié deux membres de la famille Slit et Trk (Slitrk), Slitrk2 et Slitrk5, comme contrôlant la formation des synapses excitatrices et inhibitrices afférentes aux neurones mDA. Des mutations de SLITRK2 et SLITRK5 furent également associées au développement de divers désordres neuropsychiatriques. Nous présentons ici le rôle de Lmx1a/b dans la régulation de l’activité électrophysiologique des neurones mDA, par leur régulation transcriptionnelle de Slitrk2 et Slitrk5. En utilisant un modèle de culture primaire de neurones mDA, nous avons identifié un rôle de Slitrk2 et de Slitrk5 dans la régulation postsynaptique de la synaptogénèse excitatrice et inhibitrice, respectivement. La perturbation de l’activité électrique des neurones mDA résultant de la perte ou du gain de fonction de Slitrk2/5 pourrait possiblement résulter en une perturbation de la libération de la dopamine aux noyaux cibles des neurones mDA, menant ainsi au développement de comportements pathologiques associés aux troubles neuropsychiatriques humains.Mesodiencephalic dopaminergic (mDA) neurons regulate key functions of the mammalian central nervous system, including voluntary movement, affection, reward, attention, working memory and learning. The specification of mDA neurons and dopaminergic circuitry’s establishment are finely regulated during development and require specific and complex spatial and temporal activation of transcription factors and target genes. The degeneration of mDA pathways or their dysfunction can lead to severe neurodegenerative or neuropsychiatric disorders, including Parkinson’s disease (PD), schizophrenia (SCZ) and obsessive-compulsive disorder (OCD). Lmx1a and Lmx1b transcription factors are early determinants of the dopaminergic fate, essential to mDA neurons differentiation and specification. Polymorphisms of LMX1A/B were previously linked to SCZ and OCD. Within the transcriptional targets of Lmx1a/b, we identified to members of the Slit and Trk (Slitrk) family, Slitrk2 and Slitrk5, controlling excitatory and inhibitory afferent synapses formation of mDA neurons. Mutations of SLITRK2 and SLITRK5 were also previously linked to various neuropsychiatric diseases. We here present the role of Lmx1a/b in the regulation of the electrophysiological activity of mDA neurons, by their transcriptional regulation of Slitrk2 and Slitrk5. Using a mDA neurons’ primary cell culture paradigm, we identified a role of Slitrk2 and Slitrk5 in the post-synaptic regulation of excitatory and inhibitory synaptogenesis, respectively. The perturbation of mDA neurons’ electrophysiological activity, resulting from Slitrk2/5 loss or gain of function could lead to an alteration in dopamine release to mDA neurons target nuclei, and thus to the development of pathological behaviours associated with human neuropsychiatric diseases.
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Hakanen, Eva. "Återbrukets estetik - Uppländska trasryor : Förekomst, tillverkning, funktion och värde." Thesis, Uppsala universitet, Textilvetenskap, 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-439775.
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Since the beginning of the early 20th century bed rugs have been interesting research objects, but only in passing researchers have paid attention to rugs woven with rags. Noone has taken a closer look upon the reasons why people have woven these rugs. What does the materials of the rag – like recycled garments and interior textiles in the form of clothing rags – have to tell about the times when these rugs were woven? Did the rag rugs have any specific function or were the materials available and therefore used? The main sources of information are 21 rag rugs from Roslagen in Uppland, with a varied amount of rags. They were woven during the latter half of 19th century, and estate inventories from Väddö- and Häverö Ship District have altogether given some answers to the primary question of this paper: in wich way can the examined bed rugs bear witness to the use and value of recycled textile materials and the view of these in the context of the community where they were manufactured and used? This research doesn´t give an answer to whether these rugs have any particular function or not. Instead these rag rugs can be looked upon as representing a general development of the society towards an increasing amount of textiles surplus material. This being due an increasing consumption of factory-made clothing and textiles, manufactured in factories, as well as the paper mills development from producing paper made of cellulose rather than textile waste. To this we can add a principle lingering on from the 19th century, of domestic production and a thrift of resources. This resulted in an obvious recycling of discarded textiles. The home weaving of interior textiles was still strong by the end of the 19th century, and in Rosagen there was also a long tradition of weaving and of using rugs in the beds. At the same time there was, in the coastal regions of Roslagen, a local need for warming covers in boats and boat houses. This demand was related to the shooting of seals and other hunting in the coastal areas, as well as in the fishing- and maritime trades.
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Beaubien, Francois. "Role of Slitrk family members in neurodevelopment." Thesis, McGill University, 2012. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=110496.
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The development of the nervous system is an extremely complex process where gene expression is tightly regulated, both spatially and temporally. Any gene disruption during neurodevelopment, from the complete non-transcription of the gene to a single nucleotide mutation, has the potential to lead to severe consequences in the organism. This situation is particularly well illustrated by the whole spectrum of neurological disorders affecting humans. Thanks to basic research at the gene and protein levels, some genetic causes for certain mental illness have been identified. This thesis focuses on a novel family of proteins termed the Slitrks. Initial characterization of the Slitrk family genes revealed that their expression is enriched in the central nervous system. Herein, I have performed a detailed analysis of the patterns of expression of the six members of the family in the mouse nervous system. I demonstrate that, despite some overlapping expression, several key brain regions express different combinations of Slitrks suggesting that the different family members may have distinct functions during nervous system development. I further demonstrate that members of the Slitrk family can regulate synapse formation in hippocampal neurons. More precisely, Slitrk1 is required for the formation of both excitatory and inhibitory synapses. Taken together, the results presented in my thesis indicate that Slitrks play an important role in the developing nervous system.Le développement du système nerveux est un processus extrêmement complexe pendant lequel l'expression des gènes est contrôlée de façon précise temporellement et localement. Durant le neurodéveloppement, chaque dérégulation génétique, de l'arrêt complet de la transcription d'un gène jusqu'à la mutation d'un seul nucléotide, a le potentiel de mener à de graves conséquences pour l'organisme. Cette situation est particulièrement bien illustrée par l'ensemble des troubles neurologiques qui affectent l'humain.Cette thèse se concentre sur une nouvelle famille de protéines nommées Slitrks. La description préliminaire de cette famille a révélé que leur expression est enrichie dans le système nerveux central. Par conséquent, j'ai réalisé une analyse détaillée du patron d'expression des six membres de la famille dans le système nerveux de la souris. J'ai ainsi pu démontrer que malgré certains chevauchements d'expression, plusieurs régions du cerveau expriment différentes combinaisons de Slitrks. Cela laisse présager que certains membres de la famille Slitrks peuvent avoir des fonctions distinctes durant la formation du système nerveux. Au cours de mes travaux, j'ai aussi pu démontrer que les Slitrks peuvent réguler la formation des synapses dans les neurones de l'hippocampe. Plus précisément, Slitrk1 est requis à la fois pour la formation des synapses excitatrices et inhibitrices. Dans l'ensemble, les résultats présentés dans cette thèse indiquent que les Slitrks jouent un rôle important dans le développement du système nerveux.
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Valladares, Olcese Rodrigo. "Impiego di materiali cellulari per il miglioramento delle prestazioni della slitta portamandrino di una macchina fresatrice." Bachelor's thesis, Alma Mater Studiorum - Università di Bologna, 2012. http://amslaurea.unibo.it/4759/.
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Björn, Petronella. "De starkaste armar blev slitna från plogen : Krig, pest och missväxt i Gårdby socken 1695-1721 ur ett båtsmansperspektiv." Thesis, University of Kalmar, School of Human Sciences, 2009. http://urn.kb.se/resolve?urn=urn:nbn:se:hik:diva-1020.
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Det huvudsakliga syftet med min uppsats var att studera hur tre olika aspekter påverkade Gårdby socken och dess båtsmän under Stora nordiska kriget, nämligen krig, pest och missväxt. Med hjälp av de källor jag har studerat, militära rullor, kyrkoböcker och mantalslängder, har jag fått fram hur livet kunde te sig för de indelta båtsmännen men också hur pestens verkningar påverkade socknen mer långsiktigt än vad krigets utskrivningar gjorde. Jag har även studerat hur missväxten föll ut i Gårdby och jämfört detta med till exempel byn Andersvattnet, Stockholm och övriga riket.
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Lekeš, Jonáš. "Výroba dentálních náhrad." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2013. http://www.nusl.cz/ntk/nusl-230811.
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Tato práce popisuje části dentálních náhrad, lékařské pojmy, které se s nimi vážou a vysvětluje proces a problematiku koncepce a výroby těchto částí. Různé druhy biomateriálů jako kovy, keramika, polymery či kompozity jsou zde popsány, hlavní důraz je však kladen na titanové a chrom kobaltové slitiny a korozivzdorné oceli. Experimentální část nabízí 2 řešení zlepšení výroby součásti. První část experimentální části se zabývá zlepšením kvality styčné plochy pilíře zvýšením hustoty síťování součásti. Druhá část nabízí nahrazení operace frézování operací vrtání. Byly vybrány nástoje od 4 výrobců. Pro nalezení vhodného nástroje jsou provedeny 2 testy vrtání a vybrán nástroj vhodný pro obrábění titanové a chrom kobaltové slitiny.
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Rosander, Henrik, and Selma Pasic. ""Människor är det enda djur som kan slita ut din själ och pissa på den" - En studie i hur gymnasieelever ser på ondska." Thesis, Kristianstad University College, School of Teacher Education, 2009. http://urn.kb.se/resolve?urn=urn:nbn:se:hkr:diva-4906.
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Syftet med den här uppsatsen var att jämföra hur gymnasieelever kan tänka kring ondska i förhållande till några välkända filosofernas sätt att tänka kring ondska. För att kunna ta reda på detta så gjorde vi en undersökningen på två gymnasieskolor, i två olika klasser i årskurs 3. Metoden som används var en kvalitativ undersökningsmetod, där eleverna fick skriva små uppsatser utifrån ett frågeformulär med öppna frågor. Resultaten nåddes genom analyser av dessa uppsatser, och som analysverktyg användes olika filosofiska tänkares syn på ondska. Resultaten visade att flertalet av eleverna inte hade varit med om något som de skulle vilja kalla för ondska. Många skulle hellre vilja kalla det för elakhet. Resultaten visade också att några utav dem som hade upplevt ondska beskrev detta som mobbning. Resultaten visar även att samtliga elever inte såg ondska som något transcendent, utan som något högst mänskligt, något som fanns inom människan.
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Klepárníková, Eliška. "Interakce poloroztavené slitiny s pevným materiálem při vzájemném pohybu." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2019. http://www.nusl.cz/ntk/nusl-442481.
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This thesis is deals with the suitability of Ag-Sn-Sb alloy for extrusion and selection of suitable materiál for the extruder nozzle. The theoretical part of this thesis deals with the general possibilities of 3D metal printing, especially the metal printing in the semi-solid phase and with it‘s problems. The experimental part describes the development of semi-solid alloys testing device and the research od the alloy and its interactions with solid materials in mutual motion. Analyzis of mechanical and chemical influence between alloy and solid material were performed by visual investigation and analysis of elements by EDS detector. The results of these analyzes led to the choise of nozzle material suitable for extrusion of Ag-Sn-Sb alloy.
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Cieslar, Jiří. "Studium faktorů ovlivňujících odolnost proti opotřebení kovových materiálů." Doctoral thesis, Česká zemědělská univerzita v Praze, 2016. http://www.nusl.cz/ntk/nusl-259632.
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This thesis investigates the suitable chemical composition of a iron alloy with improved wear resistance. A unique set of alloys with a specifically designated chemical composition was manufactured for experiments. Their properties in defined abrasive conditions was studied in laboratory conditions. Wear resistance was determined on an experimental bench with bound particles. Material properties description was always complemented with information gained during material metallographic structure investigations. All the results were compared with results achieved for commercially available weld deposition materials (specifically designated for abrasion conditions). These (weld deposition) materials were subjected to an identical set of laboratory experiments and additionally to a set of experiments under inservice conditions.
This thesis offers new knowledge about the relationship between material hardness, material structure and wear resistance. The outlined results also give evidence about the correlation between results gained under laboratory conditions and those gained under in-service conditions (in relation to material structure and hardness).
At the end of the thesis the knowledge gained from these experiments is applied to a specific application the service life extension of plough blade segments. On this basis a new material is designed which will extend service life without additional demands on the costs, and the approach to the renovation of worn plough blade segments is justified.
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Gamanov, Štěpán. "Příprava slitiny s vysokou entropií cestou mechanického legování." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2019. http://www.nusl.cz/ntk/nusl-400831.
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This thesis deals with topic of high entropy alloys. The teoretical part explains what are high entropy alloys, how are they different from conventional alloys, how is their chemical composition proposed and what potencial these alloys have. The experimental part describes procedures of preparation of three high entropy alloys witch consists of Co, Cr, Fe, Ni and Ti, where the concentration of all elements except Ti remains the same. These alloys were prepared via mechanical alloying and sintered by SPS process. Crucial part of this thesis is characterization of these three alloys with EDS and XRD supported by hardness measuring and tensile tests.
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Bula, Tomáš. "Zefektivnění výroby součástky do leteckého motoru." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2016. http://www.nusl.cz/ntk/nusl-241864.
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The thesis deals with innovation of the technological process of casting called Fan support in the company Honeywell Aerospace Olomouc s.r.o. The first part of the thesis is dedicated to component description which is made of titanium alloy Ti-6Al-4V. The section is also devoted to jet engine TFE 731, which is the engine where our particular component has specific function. Another part is focused on theoretical analysis of material characteristics of titanium alloys and their machinability. In the following section there are considered alternatives of machine suppliers with subsequent selection of the multifunctional CNC milling-turning center DMC 80 U duoBLOCK equipped with Jetstream technology. The transfer of the production to another machine is accompanied by an innovation of the technological process, making new fixtures and optimalization of the cutting tools. The section is also dedicated to static analysis of the component in operation 7 supported by finite element method (FEM). The final part of the thesis includes evaluation of the costs and savings achieved by innovation of the technological process.
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Ryšavá, Zdeňka. "Technologie obrábění vybrané součásti pro automobilový průmysl." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2012. http://www.nusl.cz/ntk/nusl-230050.
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Tato práce se zabývá problematikou nárůstku. Jde o řešení konkrétního průmyslového problému. Pro daný odlitek ze slitiny hliníku a řezný nástroj ze slinutého karbidu je studován výskyt nárůstku pro různé řezné podmínky. Nejprve se práce zabýva rozborem tématiky nárůstku, mechanismy jeho vzniku a parametry, které mají na jeho výskyt a růst největší vliv. Dále je věnována pozornost studiu materiálu odlitku, jeho nové koncepce a původního řešení. Během inovačního procesu došlo k obměně použitého materiálu. Tato změna se na procesu řezání projevila vznikem významného nárůstku, který vede až k úplné destrukci nástroje. Byly provedeny zkoušky tvrdosti a metalografické výbrusy pro detailní popis a srovnání vlastností obou slitin hliníku. Výsledky zkoušek prokazují rozdíly v metalografické struktuře (velikosti dendritů, množství precipitátů) a tvrdosti daných materiálů. Experimentální řešení problému spočívalo v testech vrtání do odlitků ze zkoušených slitin hliníku. Pro jednotlivé vrtací zkoušky byla měněna hodnota posuvu a řezné rychlosti. Za pomoci dynamometru byla měřena posuvová síla, dále byl použit wattmetr k určení příkonu stoje a synchroní funkce CN, jejichž výstupem byla aktuální poloha vřetene a řezný moment. Na zákldě naměřených hodnot byla vypočtena měrná řezná síla pro konkrétní testované řezné podmínky.Mimoto po každém pokusu byly pořízeny fotografie nástroje s daným nárůstkem. Z výsledků vyplývá, že měrná řezná síla má tendenci výrazně klesat se zvyšující se hodnotou posuvu, oproti tomu zvyšující se řezná rychlost nemá tak výrazný účinek na její snižování. Co se týče naměřené tloušťky nárůstku, tak se zvyšující se řeznou rychlostí dochází k jejímu poklesu. V případě růstu posuvu, má nárůstek taktéž tendenci klesat, ale menší měrou oproti předešlému případu. V závěru práce je uvedeno rozmezí řezných rychlostí a posuvů vymezující optimalizovanou zónu pro vrtání dané součásti. Následuje nabídka dalších možných experimentů vážících se k tématu studie.
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Holubářová, Michaela. "Vliv hyaluronové kyseliny na korozi hořčíkové slitiny AZ31." Master's thesis, Vysoké učení technické v Brně. Fakulta chemická, 2021. http://www.nusl.cz/ntk/nusl-445135.
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Magnesium and its alloys are interesting materials due to their many physical properties. They have considerable potential, especially in medical applications, where they can serve as a material for the production of orthopedic and cardiovascular implants. The disadvantage of these materials is their sensitivity to corrosion. As a result, it is necessary to know the corrosive properties of magnesium and its alloys in contact with substances that occur in the human body. Hyaluronan is a polysaccharide that is naturally present in the human body and can interact with implants. This master's thesis deals with the influence of low molecular weight (80–130 kDa) and high molecular weight (1 500–1 750 kDa) hyaluronan on the corrosion properties of magnesium alloy AZ31 in the environment of two simulated physiological solutions (0,9 % NaCl and synovial fluid). Potentiodynamic polarization (PD) and electrical impedance spectroscopy (EIS) were used for electrochemical tests. Surface analysis was performed using X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM) to reveal the chemical composition of the corrosion products and the surface morphology after corrosion.
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Novotný, Michal. "Technologie CNC výroby součásti z hliníkové slitiny." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2014. http://www.nusl.cz/ntk/nusl-231248.
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The diploma thesis Technology of CNC production of aluminium alloy part is based on the particular specification of the company FP cz s.r.o. The core of the work lies in the proposal of production technology of the given part made from aluminium alloy which is machined by two universal CNC lathes with operating system FANUC. There is an introduction to the issue of characteristics and machinability of aluminium and its alloys because of coherence of the thesis. Practical part is focusing on the particular proposal of production technology which consists of the casting analysis, method of clamping on the chosen machines, choice of tools and verification of the production. There can be achieved effective production and significant time reduction with proposed technology.
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Dokoupil, Filip. "Zpracování slitiny 2618 pomocí technologie selective laser melting." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2015. http://www.nusl.cz/ntk/nusl-231934.
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This diploma thesis deals with finding and verification of appropriate technological parameters of SLM technology for the processing of aluminum alloy 2618. In the theoretical part, an introduction to additive manufacturing of aluminum alloys and general description of processes occurring during SLM production is given. Based on general knowledge were designed different types of testing samples produced by sintering the metallurgical powder using 400 W ytterbium fiber laser, which so far in the literature for aluminum alloy 2618 were not described. As the result, the technological parameters dependence on relative density and the detailed overview of the 2618 alloy processing by SLM technology is determined.
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Skalka, Jan. "Svařování Ti 6Al 4V elektronovým svazkem." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2016. http://www.nusl.cz/ntk/nusl-241156.
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The thesis is dedicated to welding combination of titanium alloy Ti-6Al-4V and austenitic steels 1.4301 by electron beam. Based on literature studies of bonding titanium and its alloys with steels, it was proposed to select for welding interlayer of copper, which could limit the impact of intermetallic phases on the mechanical properties of the weld seam and enable the creation of weld. For welding the pipe samples were used three methods of welding with various welding parameters. Samples which remain after thermal cycling vacuum-tight, were then further analyzed (micro-hardness, tensile test, etc.).
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Luňák, Václav. "Možnosti CAM softwaru PowerMILL 2018 při programování obrábění tenkostěnných součástek." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2018. http://www.nusl.cz/ntk/nusl-378982.
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This master's thesis is focused on the modeling and tracks of thin-walled components. Used softwares are CATIA V5R20 from Dassault Systemes for Experimental Component Modeling and PowerMILL 2018 from Autodesk for Draw and NC Programming. The production efficiency between the precision casting and the workpiece of the cube blank based on the material utilization factor and machining time is compared in this work.
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Pořický, Vladislav. "Hodnocení koroze u vybraných typů hořčíkových slitin." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2009. http://www.nusl.cz/ntk/nusl-228886.
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This master´s thesis is focused on classification of corrosion resistivity magnesium alloy type AZ91 in environment of salt vapour testing in corrosion chambers. For tests were used samples of magnesium alloy manufactured by three different methods of casting: cast-iron mold, die vacuum casting, die casting without vacuum and method of die casting with additional pressure (squeeze casting). In this work was accomplished metallographic evaluation of corrosion attack and detailed analysis of corrosion products. Conclusions of exposits tests are assembled of analysis of influence of corrosion environment on structure of alloy. On the basis of these conclusions of corrosion tests were evaluated influences of corrosion speed [mm/year] on time [hours] for individual states of magnesium alloy.
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Pišek, David. "Vysoce-entropické slitiny – objemové slitiny a povrchové úpravy." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2017. http://www.nusl.cz/ntk/nusl-318856.
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Master‘s thesis deals with the preparation and evaluation single-phase high-entropy alloy based on cobalt, chromium, iron, nickel and manganese and its variants strengthened by dispersion of oxidic particles. High-entropy alloy was prepared in powder form by mechanical alloying from the equiatomic proportions of atomic powders. Obtained powder was subsequently compacted by spark plasma sintering. By the method of mechanical alloying were successfully prepared single-phase high-entropy alloy and its variant strengthened by dispersion of nanometric yttria oxides. It has been found that the oxide particles present in the microstructure of high-entropy alloy significantly block mobility of grain boundary and dislocation at elevated temperatures. As a result of this behavior were observed doubling of alloy strength and decreasing of creep rate at 800 °C.
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Havlíček, Štěpán-Adam. "Vysoce entropické slitiny Cantorova typu zpevněné disperzí nitridů." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2020. http://www.nusl.cz/ntk/nusl-432460.
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High Entropy Alloy (HEA) is a class of construction steels based on the mixing of five or more elements in approximately equimolar ratios. Despite the ambiguity of their future use, HEAs represent a significantly new group of construction materials that are currently receiving a great deal of attention. Single-phase HEAs fail when used at elevated tempera-tures. The improvement of their high-temperature resistance was achieved by introducing a dispersion of oxides Al2O3 and Y2O3. To generalize the positive effect of dispersions on the mechanical properties at elevated temperatures, particles of a similar nature were cho-sen. These were dispersed particles of nitrides: hardness-incompatible AlN and hardness-compatible BN. The particles were evenly distributed inside the alloys by mechanical al-loying and compacted by SPS (Spark Plasma Sintering). The new structural alloy reached a density higher than 96.5 % and brought an increase in yield strength at room tempera-ture of up to 67 % and 40 % at elevated temperatures, while maintaining a homogeneous distribution of input powders.
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Svoboda, Rostislav. "Tlakově lité odlitky z Mg slitin - trendy vývoje." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2008. http://www.nusl.cz/ntk/nusl-228049.
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The aim of this thesis is to determine influence of porosity and shape-factor over mechanical properties, performed on cast samples from Aalen foundry (Germany), that were high pressure die casted from AZ91 D Alloy. Evaluation of these quantities was done using computer software Olympus Five. Measured values were subjected to statistical analysis in order to eliminate gross errors and determine linear dependence between mechanical properties and porosity eventually voids shape factor.
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Věrný, Luděk. "Technologie CNC výroby součástí z hliníkových slitin." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2011. http://www.nusl.cz/ntk/nusl-229842.
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This diploma thesis is elaborated on the specific assignment of AB Komponenty Ltd. The core of this thesis features the technology of manufacturing of component BASE CROSSBAR of aluminium alloy EN AW 2017 on the vertical machining center. CNC control program for the suggested technology is developed in the CAM software PowerMill 2010th. To complete the work it also includes a brief introduction to the issues and analysis of aluminum, aluminum alloys and coatings. From the perspective of the practice is probably the most beneficial and interesting final technical economic evaluation of selected solution of the given problem. The suggested technology can be a significant saving in production costs.
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Pohorecka, Magdalena. "Rôle de c-Jun dans la réponse aux inhibiteurs de la voie des MAPK dans les mélanomes." Thesis, Toulouse 3, 2018. http://www.theses.fr/2018TOU30373.
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Il est clairement admis que la voie des MAPK est essentielle à la mélanomagenèse. Le développement de nouveaux médicaments ciblant cette voie, tels que les inhibiteurs de BRAF et/ou de MEK, a constitué une avancée majeure dans la prise en charge thérapeutique du mélanome. Cependant, les patients rechutent systématiquement sous traitement, ce qui suggère l'émergence de mécanismes de résistances. De nombreuses études montrent que l'expression et l'activation du facteur de transcription c-Jun sont induites après traitement de cellules de mélanome BRAF-mutées par des inhibiteurs de la voie des MAPK (MAPKi). De plus, la déplétion de c-Jun sensibilise ces cellules à ces inhibiteurs en induisant l'apoptose. Nous avons transfecté des lignées cellulaires de mélanome BRAF-mutées par des siARN dirigés contre c-Jun et traité ces cellules avec un inhibiteur de BRAF (PLX4032). Nous avons ensuite analysé l'expression du génome par une étude de transcriptomique afin de déterminer les gènes cibles de c-Jun qui pourraient être impliqués dans la réponse pharmacologique aux MAPKi. Cette étude a révélé que SLIT And NTRK Like Family Member 6 (SLITRK6) est un gène cible de c-Jun qui pourrait être associé à une réponse pharmacologique antitumorale aux MAPKi. En effet, l'ARNm et la protéine SLITRK6 sont induits dans les lignées cellulaires de mélanome BRAF-mutées après traitement par inhibiteur de BRAF seul ou en association avec un inhibiteur de MEK (AZD6244). Nous avons également montré que la combinaison des inhibiteurs de la voie des MAPK avec un anticorps conjugué à un cytotoxique ciblant SLITRK6 augmente la mort des cellules de mélanome BRAF-mutées en induisant de l'apoptose in vitro. Finalement, nos travaux montrent que SLITRK6 pourrait être une nouvelle cible pharmacologique pour le traitement du mélanome métastatique BRAF-muté et/ou être un biomarqueur potentiel de cellules résistantes aux MAPKiIt is clearly recognized that the MAPK pathway is essential for melanomagenesis. The development of new drugs targeting this pathway such as BRAF inhibitors and/or MEK inhibitors has been a major advance in the therapeutic management of melanoma. However, patients still relapse suggesting the emergence of mechanisms of resistance. Many data show that both the expression and activation of the transcription factor c-Jun are induced after treatment of BRAF-mutant cells with MAPK pathway inhibitors (MAPKi). Furthermore, depletion of c-Jun sensitizes cells to these inhibitors triggering apoptosis. We depleted BRAF-mutant melanoma cell lines for c-Jun by siRNA and treated cells with a BRAF inhibitor (PLX4032). Whole genome expression was then analysed by transcriptomic study to determine target genes of c-Jun that could be associated with pharmacological response to MAPKi. This study revealed that SLIT And NTRK Like Family Member 6 (SLITRK6) is a target gene of c-Jun that could be associated with antitumor pharmacological response to MAPKi. Indeed, SLITRK6 mRNA and protein are induced in BRAF-mutant melanoma cell lines after BRAF inhibitor treatment alone or in combination with MEK inhibitor (AZD6244). We also show that the combination of MAPKi with an antibody conjugated with a cytotoxic drug targeting SLITRK6 increases BRAF-mutant melanoma cell death triggering apoptosis in vitro. Finally, our data show that SLITRK6 could be a new pharmacological target for the treatment of BRAF-mutant metastatic melanoma and/or a potential biomarker of resistant cells to MAPKi
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Kolařík, Martin. "Optimalizace výroby hliníkového odlitku s použitím numerické simulace." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2019. http://www.nusl.cz/ntk/nusl-401577.
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The master’s thesis deals with the analysis of casting technology of the selected aluminium casting. It is a casting of a part of CNC milling machine and it is cast by gravity casting into a permanent mold. The defects which are the cause of a high percentage of nonconforming production were analyzed. Furthermore, the master’s thesis includes a complete analysis of filling and solidification of this casting in the ProCast simulation program. Numerical simulation results are verified and improved. Then the causes of problematic casting defects are proven on several calculated variants. Measures are proposed to minimize the tendency to produce castings with defects leading to nonconforming production.
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Těšík, Martin. "Obrábění materiálů pro specifické dentální aplikace." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2019. http://www.nusl.cz/ntk/nusl-402520.
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This diploma thesis is focused on dental materials used in prosthetic medicine. In the introduction, the most important characteristic of dental materials is summarised, which is biocompatibility. Further it contains distribution of nowadays used dental materials, which are oxidic ceramics and titanium alloys. It describes pitfalls of machining of those materials. Final part is devoted to process of the production of the new dental crown, from the first arrival of the patient to the machining of final product. The thesis also compares the economics of dental crown production using milling and 3D printing.
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Šomanová, Pavlína. "Příprava a charakterizace vysoce hydrofobních povlaků na hořčíkové slitině AZ91." Master's thesis, Vysoké učení technické v Brně. Fakulta chemická, 2021. http://www.nusl.cz/ntk/nusl-444211.
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Magnesium and its alloys have many interesting properties and thanks to them it can be used in many applications (transport industry, medicine etc.). Disadvantage of these materials is their high corrosion rate. For this reason, there is an effort to achieve high corrosion resistance through different modifications of magnesium and its alloys. In recent years the superhydrophobization of the surface seem to be an attractive solution for this question. This type surface modification minimalize contact between the surface and water. In this diploma thesis the superhydrophobic surface was created on the magnesium alloy AZ91. The first step included pretreatment of AZ91 surface by etching in solution of SnCl2 or ZnCl2. Next step was superhydrophobization in the ethanolic solution of stearic acid. The surface morphology and elemental analysis of the superhydrophobic coating were explored by use of scanning electron microscope (SEM) and energy dispersive X-ray spectroscopy (EDS). The adhesion properties of the coating on the AZ91 were analysed by means of scratching test. Contact and sliding angles were measured for superhydrophobic coatings. Electrochemical characterization of the coatings was determined using potentiodynamic polarization (PD) and electrochemical impedance spectroscopy (EIS). Finally, the analysis of composition and the functional groups was made using Fourier-transform infrared spectroscopy (FTIR) and the phase composition analysis was performed using X-ray diffraction (XRD). The results show that the coatings prepared by etching did not lead to good corrosion properties, even though the value of contact angle was about 150 °. The reduction of corrosion resistance could be caused by not obtaining required surface morphology or insufficient binding of stearic acid in the form of stearate to the sample surface.
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Slabý, Ondřej. "Produktivní obrábění titanových slitin." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2012. http://www.nusl.cz/ntk/nusl-230126.
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This diploma thesis is focused on a productive machining of titanium alloys. At the beginning it deals about titanium and its alloys. It describes chip generation mechanism, tool blunting and surface quality. Further it contains modern strategies of efficient titanium alloys machining. Then it analyzes contemporary manufacturing technology of hinge made of titanium alloy Ti-6Al-4V in Frentech Aerospace s.r.o. company, and at the end finds possibility of savings by inovation of roughing process.
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Klíma, Jan. "Hluboké vrtání leteckého dílu." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2013. http://www.nusl.cz/ntk/nusl-230980.
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Diploma thesis deals with problems about deep drilling of aeronautical part made of aluminum alloy EN AW 7075 T7351. This work is focused on the material properties component and current aluminum alloys processing. Further it contains a part delicated to various kinds of technologies of deep drilling, primarily is focused to gun drilling. Describes a tool, technology and conditions in gun drilling of deep holes with focused to analysis of the forces. Then it compares contemporary manufacturing technology of part drilling in cooperation and proposes an innovative technology of manufacturing. This project is accomplished with technical-economical evaluation.
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Hlavnička, Radek. "Únavové vlastnosti ultrajemnozrnných Mg slitin." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2014. http://www.nusl.cz/ntk/nusl-231379.
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This thesis deals with the influence of grain refinement by ECAP on fatigue properties of magnesium alloy AZ 91. Tensile and fatigue tests were made on the as-cast state samples and samples after ECAP process. Metallographic analysis of the microstructure and fractographic analysis of the fracture surfaces was performed.
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Buchtík, Martin. "Příprava povlaků na bázi Ni-P na tvářených hořčíkových slitinách." Master's thesis, Vysoké učení technické v Brně. Fakulta chemická, 2016. http://www.nusl.cz/ntk/nusl-240523.
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The aim of this diploma thesis was summary of all steps and knowledge necessary to deposition of quality Ni-P coatings deposited on wrought magnesium alloys AZ31 and AZ61. There is the treatise about wrought magnesium alloys AZ31 and AZ61. Thesis includes its phase composition in the theoretical part. There are given its possible processing methods too. Next, there is desribed the mechanism of deposition of Ni-P coatings, components required to electroless deposition and factors affecting the quality and properties of these coatings. The theoretical part is ended by serie of reviews. Authors of these reviews deal with pretreatment of substrates, preparation, characterization and measuring of mechanical, structure and corrosion properties of deposited coatings. The optimalization of pretreatment, parametres and composition of nickel bath suitable for magnesium alloys is described in experimental part. The microstructure, present interlayer between substrate and Ni-P coating and chemical composition of deposited coatings was observed and measured by optical and electron microscopy. The mechanical characterization of Ni-P coatings was performed by microhardness tester.
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Dukovský, Daniel. "Depozice bioaktivních keramických vrstev pomocí technologie RF-ICP." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2021. http://www.nusl.cz/ntk/nusl-442600.
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Tato diplomová práce se zabývá problematikou plazmového nanášení bioaktivních keramických povlaků hydroxylapatitu s využitím technologie radio-frekvenčně buzeného indukčně vázaného plazmatu. Cílem bylo optimalizovat proces a nanést kompaktní hydroxylapatitové povlaky na substráty z titanové slitiny Ti6Al4V. Nanesené vzorky byly následně podrobeny analýzám povrchové drsnosti, mikrostruktury a fázového složení. Ze získaných výsledků byly vyvozeny závěry, které byly srovnány s dalšími odbornými pracemi zabývajícími se příbuznou problematikou.
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Horynová, Miroslava. "Únavové charakteristiky hořčíkové slitiny AZ31 po korozní degradaci." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2011. http://www.nusl.cz/ntk/nusl-229931.
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The present study is focussed on assessment of cyclic deformation response and fatigue behaviour of bare and precorroded AZ31 magnesium alloys. Corrosion degradation was carried out in a salt spray fog (5% solution of sodium chloride) for 480 and 1000 hrs. Microstructure, mechanical properties, low- and high-cycle fatigue behaviour of experimental material in as-cast condition has been evaluated. Furthermore, the corrosion behaviour of material has been investigated. The fatigue tests have been performed using precorroded specimens to assess influence of corrosion degradation on cyclic deformation response and on low- and high-cycle fatigue behaviour. Influence of local corrosion degradation on initiation of fatigue cracks has been studied.
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Lačňák, Martin. "Obrábění součásti ze slitiny hliníku." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2013. http://www.nusl.cz/ntk/nusl-230784.
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The thesis focuses on the technology of production of the turbine-type component in Edwards company. It specifically focuses on the part of the turning production, in which in the first part an analysis of the component and the technologicity of its construction is created. Problematic aspects are analysed in terms of material structure and procedure technology. An evaluation of the former and the new supplier is made in terms of rationalization of material structure and their statistical evaluation of rationalization improvement towards keeping to geometrical tolerances. Grooving tools greatly influence the overall machining time during turning. An experiment is made to find out the measured values of the radial forces, the process of chip formation and surface roughness during grooving. The technology of procedure further deals with rationalization of the current machine OKUMA LU25-M and purchase of a new machine Mori Seiki NTX 2000, for which new tool equipment is made in cooperation with Walter company. The final technical-economical evaluation sums up all findings from the research of the given issue. In the discussion, further continuation is suggested for the research in the development and for the continuously controlled component productivity.
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Hanáček, Josef. "Modifikace mikrostruktury hořčíkové slitiny Elektron 21 pomocí technologie elektronového paprsku." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2018. http://www.nusl.cz/ntk/nusl-377873.
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This work presents a basic research on the influence of electron beam technology modification on chemical, structural and phases changes of Elektron 21 magnesium alloy. The samples were systematically modified under various parameters of the electron beam and coatings on their respective surfaces were deposited via controlled plasma electrolytic oxidation (PEO) subsequently. The influence of the EB modification on the PEO coating formation was observed. Several samples with remelted fine-grained surface layer were obtained. Having a thickness of 10^1 to 10^3 µm, the average grain sizes in this layer were quantitatively evaluated. The performed EDS analysis revealed in identical chemical composition of the remelted surface layer and the original alloy material, despite the detected sample weight loss upon the EB treatment. XRD analysis revealed an increased content of Mg3(Nd,Gd) intermetallic phase in the remelted area. The PEO coatings were more compact and less porous as compared with their counterpart coatings on the original, unmodified alloy material.The results of the presented work showed, among others, a suitable microstructure and chemical composition of some of the modified samples that could potentially exhibit enhanced corrosion resistance as opposed to the unmodified material. The corrosion testing will be part of a follow-up study. More compact PEO coatings formed on some of the modified surface layers likely represent, too, a more durable variant as compared to the original material.
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Chloupek, Tomáš. "Hodnocení materiálových a procesních faktorů na DPS metodou smáčecích vah." Master's thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2009. http://www.nusl.cz/ntk/nusl-217899.
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This work deals with issues of the wetting forces during soldering and evaluates material and procedural effects on the soldering process. The aim is to set the technology operations to get best quality of soldered joints.
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Svozil, Libor. "Mechanicko-strukturní charakteristiky slitiny hořčíku AZ61." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2010. http://www.nusl.cz/ntk/nusl-229290.
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Microstructure and mechanical properties of AZ61 magnesium alloy in cast condition and after solution annealing were compared. The compare of mechanical properties of alloy, their hardness and microanalysis of occurring phases are included in this work. For compare has been used a light microscopy, tensile test, hardness measurements and scanning electron microscopy.
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Ozomaro, Uzoezi. "The Genetic and Functional Analysis of the Obsessive-Compulsive Disorder Spectrum." Scholarly Repository, 2011. http://scholarlyrepository.miami.edu/oa_dissertations/602.
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Obsessive-compulsive disorder (OCD) and the spectrum of associated conditions, affect 2-4% of the population worldwide. Although heritability studies in OCD have shown a 3 - 12 times increased risk for first degree relatives, the identification of the underlying risk-conferring genetic variation using classic genetic association studies has proven to be difficult. The possibility of a larger contribution of rare genetic variants to the risk of psychiatric disorder has been suggested by several successful studies. We expect that a spectrum of risk allele frequencies exists, which includes not only common variation but also a substantial amount of rare genetic variants that contribute to OCD. This thesis is aimed at identifying and functionally characterizing rare genetic variation in the OCD spectrum. Identified statistically significant variants were scrutinized for changes related to synaptic function using high content screening and subsequent functional analyses. Identifying the genetic profile of rare variants found in the OCD spectrum cohort combined with the functional impact that these variants have has provided insight into the etiology of the OCD spectrum. With these approaches a foundation can be laid for the development of a predictive model of the OCD spectrum.
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Hlavnička, Jiří. "Struktura a vlastnosti hořčíkových slitin Mg-Ca-Zn." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2014. http://www.nusl.cz/ntk/nusl-231148.
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This master’s thesis deals with design and preparation of a new biodegradable magnesium alloy based on Mg-Ca-Zn. Based on information from literature, the Mg-3Zn-2Ca alloy was designed. The base material was produced by gravity casting and the evaluation in the as-cast and heat treated state was performed. For preparation of the experimental material, following methods were designed: squeeze casting, hot rolling and the ECAP. During preparation by hot rolling, no optimal conditions were found and significant cracks occurred in both as-cast and heat treated material. In the case of experimental material, prepared by the ECAP method with back-pressure, better combination of stress-strain properties was observed. Also the squeeze casting method showed improvement; especially the amount of casting defects was eliminated. The evaluation of microstructure and mechanical properties was performed by the light and scanning electron microscopy, RTG phase analysis and the tensile and compression tests.
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Gejdoš, Pavel. "Studium nízkocyklových únavových vlastností hořčíkové slitiny AZ31 s 0,5% vápníku." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2009. http://www.nusl.cz/ntk/nusl-228608.
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In this work have been identified mechanical and fatigue properties of magnesium alloy AZ31 with 0.5% calcium, which was cast using squeeze casting. In addition, it was observed microstructure of the alloys and made fractographic assessment of fracture surfaces after fatigue loading.
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Vašáková, Kristýna. "Mechanické vlastnosti materiálů připravovaných pomocí procesu SLM." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2019. http://www.nusl.cz/ntk/nusl-400837.
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This diploma thesis deals with properties of multi-materials interface composed of pure iron and Cu7Ni2Si1Cr alloy produced by SLM process. The theoretical part of thesis is focused on selective laser melting technology, and on description of defects connected with the production of SLM parts. Furthermore, one section deals with the production of multi-materials prepared by the SLM process. The experimental part of this thesis deals with selections of the SLM process parameters appropriate for bulk samples preparation. Mechanical properties were determined by the tensile tests at room temperature. Metallographic and fractographic analyses were performed for evaluation of the microstructure and description of the fracture mechanisms.
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Matlák, Jiří. "Modifikace povrchu kovových materiálů s využitím elektronového svazku." Doctoral thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2019. http://www.nusl.cz/ntk/nusl-409083.
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Fast deflection is one of the great advantages of an electron beam, making it possible to process a relatively large area at once and also to modify the distribution of the supplied energy. The dissertation deals with surface heat treatment with a focus on the effect of beam deflection on the process. Furthermore, the influence of processing speed and defocusing of the electron beam is studied. The principles of electron beam technology and the summary of surface heat treatment of various materials are presented in the literary part of the thesis. The experimental part is focused on the influence of process parameters on processing in the solid phase, carried out on steel 42CrMo4, and in in the liquid phase, carried out on alloy NiCrBSi. Especially changes in structure, hardness, shape of the processed area and wear resistance are evaluated on processed samples. The results are also evaluated from an energy perspective. Furthermore, an optimum combination of technological parameters is recommended for solid and liquid phase surface heat treatment.
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Smeliková, Lenka. "Kontrola kvality pájeného spoje a Design of Experiments u strojního pájení vlnou." Master's thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2014. http://www.nusl.cz/ntk/nusl-220991.
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This master´s thesis deals with problems of wave soldering and application methods Design of Experiments for the new product production. Summarizes the basic knowledge of soldering technology, of solder alloys and Design of Experiments methods. Design of Experiments method has been applied to product to find the optimal for wave soldering setting.
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Krahula, Karel. "Analýza změn struktury a vlastností slitiny Al-Si během odstátí taveniny." Doctoral thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2021. http://www.nusl.cz/ntk/nusl-446742.
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This thesis is dedicated to the production of aluminum casting alloys. It maps the course of changes in the morphology of eutectic and its influence on mechanical properties during the long-term meltdown. In particular, the use of image analysis methods contributes to describing these processes. The presented results show that the eutectic shape does not change even during the meltdown for 110 minutes. There is only a roughing and an increase in grain size. There was also no influence on the mechanical properties that fit the practical application of the alloy examined
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Plundrák, David. "Analýza příčin vzniku trhlin v ráfcích kol." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2013. http://www.nusl.cz/ntk/nusl-230459.
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This thesis looks for the causes of cracks in bicycle rims in the most stressed areas (in places holes for wires). For this reason, in this work is the stress and strain analysis of a simple model of the rim to the working load is given and further the complete production process of the rim is described. As an experimental material were used rims from different producers of aluminum alloy EN AW 6061 and EN AW 6082 T6 temper, in which a crack started to spread. For assessment of rims materials the methods of optical spectroscopy, optical microscopy, scanning electron microscopy, Vickers hardness test were used and for finding another crack penetration test was performed. Based on the performed experiments bad design solution of rivets was found in the rim 1. Broken rivets initiated fatigue cracks. Material of rim 1 was alright. The other two rims were deficiencies in materials. For the rim 2 was a problem with coarse-grained recrystallized structure. The insufficiently rapid cooling for the rim 3 caused exclusion hardening phase (particularly copper phase) at grain boundaries. Moreover, the rim 3 is not cured to the required parameters. Aluminium alloys are an ideal material for bicycle rims. However, they require reliable design solutions and meeting the physical metallurgy, which lies in the knowledge and use of influences of chemical composition, forming and heat treatment on mechanical, chemical, physical and technological properties.
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Kaňová, Monika. "Nízkocyklová únava pseudoelastické slitiny NiTi." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2013. http://www.nusl.cz/ntk/nusl-230847.
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This work is focused on study of mechanical properties of NiTi alloy which shows pseudoelastic and shape memory behaviour. Functional and structural fatigue of the material is examined. The main aim of this work was to perform and to evaluate a series of fatigue tests. The material was supplied in the form of wire which was gripped in the machine using special grips. In the first part of the experiment, tensile tests are evaluated and the reproducibility of measurements is demonstrated. Then, a series of cyclic tests was performed. Results were analysed together with previous measurements. One part of discussion concerned changes of the hysteresis loops during cycling and their dependence on strain rate. The fatigue life curves were plotted. It was found that these curves have non-standard shapes. The reasons for this are explained in the work.
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Ševčíková, Barbora. "Koroze neželezných kovových materiálů." Doctoral thesis, Vysoké učení technické v Brně. Fakulta chemická, 2018. http://www.nusl.cz/ntk/nusl-390295.
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In the presented dissertation thesis, I closely focused on corrosion resistance of non-ferrous metals. For full understanding of the possibilities for increasing corrosion resistance, it was vital to initially recognize the influences to the corrosion system of the samples and their surrounding environment. For this purpose, I focused on heat treatment, corrosion, and protective coatings, in the theoretical part of the thesis. For the subsequent research, it was necessary to define several constant variables, first. For this purpose, I have chosen a group of magnesium alloys, namely AZ91 Alloy and 3.5 % NaCl Electrolyte. AZ91 Alloy is of heterogenous structure formed by a solid solution of aluminum in magnesium, intermetallic phase in Mg17Al12, and their eutectic. Local microcells tend to occur in these heterogenities, which leads to faster corrosion. In order to increase corrosion resistance of the alloy, I used a combination of heat treatment and protective phosphate coating. For creating of the desired structure, which further affects compact coating formation, I selected a process involving solution heating with precipitation hardening T6. Secondary goals of the thesis involved optimization of standard technical procedures for the sake of increasing efficiency. With regard to this goal, I introduced optimized heat treatment T6 using accelerated cooling of a sample in water and liquid nitrogen. A modification besides the standard phosphating procedure was carried out with no activation step. For evaluation of corrosion resistance of the samples, I conducted water immersion tests using electrochemical methods; such as potenciodynamic curves combined with electrochemical impedance spectroscopy. In order to streamline the evaluation of the corrosion surface in technical practice, I used automatic detection. Substantial improvement of corrosion resistance of the above mentioned system, compared to heat-untreated samples, was proven through electrochemical methods. Due to accelerated cooling, a more homogeneous structure was achieved, which could be further utilized to create more uniform protective coating. For some phosphate coating, specifically manganese phosphate coating, I identified certain modifications that were in line with the set goals; i.e. skipping the activation phase, and using automatic detection for evaluation of uniform corrosion on the samples.
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Gejdoš, Pavel. "Únavové chování hořčíkových slitin AZ31 a AZ61." Doctoral thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2014. http://www.nusl.cz/ntk/nusl-234227.
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This doctoral thesis deals with the fatigue behaviour of AZ31 and AZ61 magnesium alloy casted by advanced methods of casting squeeze casting. Based on the regression functions and measured fatigue data were determined fatigue characteristics of these alloys. The work also extends into the area of fatigue cracks in the AZ31 alloy. Were measured fatigue crack propagation rate on modified cylindrical specimens. The paper also outlines the possibilities for describing the fatigue behaviour of AZ61 alloy in extremely low-cycle fatigue.
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Darida, Jiří. "Mechanické vlastnosti hořčíkové slitiny AZ91E připravené metodou ECAP." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2016. http://www.nusl.cz/ntk/nusl-254287.
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This thesis deals with mechanical and fatigue properties of magnesium alloy AZ91 processed by EX-ECAP method. This method involves the application of extrusion followed by equal-channel angular pressing. To obtain basic mechanical characteristics, the tensile test were carried out at room and elevated temperatures. Further the fatigue tests were performed and obtained data were used to compile S-N curve. The work also includes metallographics analysis of microstructure and fractographic analysis of fracture surfaces of tensile and fatigue test specimens.
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Zahálka, Martin. "Galvanické pokovování hořčíkové slitiny s Ni-P bond coat." Master's thesis, Vysoké učení technické v Brně. Fakulta chemická, 2019. http://www.nusl.cz/ntk/nusl-401926.
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Cílem této diplomové práce jse najít nejnižší možnou tloušťku nikl-fosforového povlaku, který může být galvanicky pokoven mědí bez defektů na horčíkové slitině, nikl-fosforového nebo měděného povlaku. V teoretické části jsou shrnuty poznatky o hořčíkových slitinách a jejich korozi. Navíc se teoreticá část zaměřuje na popis procesu bezproudého niklování a elektrochemického pokovování mědí a jejich porovnání. Na konci teoretické části je shrnut současný výzkum o elektrochemickém pokovování hořčíkových slitin. V experimentální části byl popsán proces přípravy povlaků Ni-P a Cu na horčíkové slitině AZ91. Na jedné vrstvě a dvojité vrstvě Ni-P povlaku byla provedena elektrodepozice mědi. Navíc byl diskutován vliv předůpravy před samotnou elektrodepozicí mědi. Za účelem zjištění korozních vlastností vzorků byl vykonán potenciodynamický test. Následně byly připraveny metalografické výbrusy jednotlivých vzorků a pomocí světelného a rastrovacího elektronového mikroskopu byla provedena charakterizace. Na konec bylo zjištěno prvkové složení jednotlivých povlaků pomocí EDX analýzy.
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Vlašic, František. "Hodnocení cyklického poškození slitin na bázi hliníku a hořčíku s využitím metody akustické emise." Doctoral thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2011. http://www.nusl.cz/ntk/nusl-233965.
Full textAbstract:
The thesis deals with the application of nondestructive testing methods (acoustic emission, electron microscopy, X-ray diffraction topography) to description and identification of stages in the fatigue process in aluminium alloys. The main contribution of this dissertation thesis consists of the approach and evaluation methodology of cyclic damage in the materials. It dealt especially with the verification of measured data by using data obtained using other nondestructive methods. The experimental results show that the field of nondestructive testing materials can fundamentally uncover the process of fatigue damage and improve current knowledge in this area. Combination of used methods has become a powerful tool for the identification and monitoring of the whole fatigue degradation process of materials.