Analysis of the transport properties of graphene nanostructures

V této práci jsou analyzovány transportní vlastnosti grafenu. Ty jsou velmi závislé na dopování nosiči náboje. Počet nosičů náboje může být ovlivněn elektrickým polem, substrátem či povrchovou úpravou. Připravovány byly unipolární tranzistory (FET). Grafen vytvořený metodou chemické depozice (CVD) byl nakontaktován na zlaté struktury vytvořené elektronovou litografií (EBL). Sledována je závislost na elektrodové konfiguraci, hradlovém napětí a substrátu.Graphene transport properties are analysed in this thesis. They are strongly dependent on doping with charge carriers. The number of charge carriers can be influenced by electric field, substrate or surface adsorbates. The graphene field-effect transistor (FET) has been prepared. Graphene made by chemical vapor deposition (CVD) has been con tacted through gold structures made by electron beam lithography (EBL). Dependences on electrode configuration, gate voltage and used substrate are observed.

Měření hysterezní smyčky a optimalizace šířky pólového nástavce synchronního stroje s permanentními magnety

The first part of this paper deals with the measuring of hysteresis loop of the toroidal shape core. LabVIEW software is used to automate this process. The results are compared with the data from the manufacturer and used in the FEMM software for setting parameters of the stator core of Permanent magnet synchronous motor (PMSM). Then, in the second part of this paper, the Lua scripting engine in FEMM software is used to optimize stator tooth width. Program code is written in the Matlab environment and after starting the run process, Matlab uses inter-process communication via ActiveX to connect with FEMM. In this process program tries several options for the stator tooth width. Based on the results, user can evaluate all the data about the overall progress and choose the optimal stator tooth width.První část této práce se zabývá měřením hysterezní smyčky toroidního jádra. Prostředí Labview je použito k automatizaci tohoto procesu. Výsledky jsou porovnány s daty od výrobce a použity v programu FEMM pro nastavení parametrů jádra statoru synchronního motoru s permanentními magnety (PMSM). Ve druhé části je poté použit skriptovací prvek Lua v programu FEMM k optimalizaci šířky pólového nástavce. Kód programu je sepsán v prostředí Matlab a po jeho spuštění proběhne navázání komunikace Matlabu s FEMM pomocí Activex. V tomto procesu program vyzkouší několik možností pro nastavení šířky pólového nástavce. V závislosti na těchto výsledcích pak uživatel může vyhodnotit všechna data ohledně celkového průběhu výsledků a rozhodnout se pro optimální šířku pólového nástavce

The study of pneumatic transport material

Tato bakalářská práce rešeršního typu je rozdělena do několika částí. Shrnuje základní rozdělení pneumatických dopravníků, problematiku přenosu materiálů s odlišnými charakterovými vlastnostmi. Dále popisuje specifický druh přenosu kusovitého materiálu a inovační systémy.This Bachelor´s thesis is written as an exploration of facts and it is divided into several parts. It consists of description of pneumatic conveying systems, material´s properties and their conveying problems. There is a description of pneumatic post and innovatory systems in this thesis, too.

Environmentally efficient 316L stainless steel feedstocks for powder injection molding

In this study, environmentally convenient highly metal powder filled feedstocks intended for powder injection molding is presented. The composition of 60 vol % 316L stainless steel gas atomized powder feedstocks containing semicrystalline waxes: acrawax or carnauba wax and paraffin wax, combined with polyethylene glycol and modifier, was optimized to provide defect-free parts. Rheological as well as thermogravimetric analyses supported with scanning electron microscopy and metallography were employed to set up optimum conditions for molding, debinding and sintering. The performance of the novel feedstock was compared with currently available polyolefines-based materials, and results showed an efficiency enhancement due to the substantially lower (about 100 °C) mixing and molding temperatures as well as a reduction of debinding and sintering times at the simultaneous achievement of better mechanical properties in terms of elongation and tensile strength, in comparison to the mass production feedstock. © 2020 by the authors.TBU in Zlin [IGA/CPS/2018/006, IGA/FT/2019/001]; Ministry of Education, Youth and Sports of the Czech Republic-Program NPU I [LO1504

Advanced technology for grinding of aluminium alloys parts

In the presents the aluminium and its alloys is doing high advanced technical materials whose proprieties use in the automotive and aerospace industry. In the production of products is effort of producer to production of parts quality and machine with acceptable price. The machining is making important portion by production of the machine parts of automotive industry. The long-terms opinions on the grinding of aluminium alloys in relation to lost of cutting power (glued up of wheel and impaction of pores) important terms there are not so use for aluminium alloys grinding and surface quality. The competition of grinding to advanced production method e.g. forming and turning with advanced tools do not threat dominance of these methods. The use of grinding we are finding in the minor series of production where the use of CNC and forming machines is not suitable in view point of price. The customer requirement of quality (roughness and geometrical accuracy) by grinding of aluminium alloys is guaranteed and correspond with normal and precision grinding e.g. for steels and hardened steels

NEUTRONIC ANALYSIS OF THE CANDIDATE MULTI-LAYER CLADDING MATERIALS WITH ENHANCED ACCIDENT TOLERANCE FOR WWER REACTORS

The paper summarizes preliminary results of neutronic analysis of candidate ATF cladding materials that are under development at the CTU in Prague. To evaluate basic neutronics-related characteristics the Serpent code was used which is a Monte-Carlo based simulation tool. A model of WWER fuel was developed and basic neutronic analysis performed. All coating materials entail certain reactivity penalty compared to reference uncoated cladding that was quantified. The coating of cladding affects also other neutron-physical parameters of cores that modify the performance of the WWER reactors that are discussed