Production of cemented carbide tools using technology of multiaxial pressing

Tato bakalářská práce je zaměřena na řezné nástroje, které jsou vyrobeny ze slinutých karbi-dů. V této práci je charakterizován vývoj slinutých karbidů, rozdělení slinutých karbidů, mate-riály, ze kterých se slinuté karbidy vyrábějí a proces výroby povlakovaných a nepovlakova-ných slinutých karbidů. Cílem této práce je přiblížit postup výroby břitových destiček pomocí víceosého lisování ve firmě Pramet Tools s.r.o.This thesis is focused on cutting tools made of cemented carbides. In this thesis are characte-rized the development of cemented carbides, distribution of cemented carbides, materials from which the cemented carbide are produced, the production proces of coated and uncoated cemented carbides. Target of this paper is to explain the production process inserts by using multiaxial pressing in company Pramet Tools Ltd.

Losses Analysis of Induction Machines with Small Output Power

Hlavními cíli této dizertační práce jsou analýza ztrát malého asynchronního motoru a studium opatření, která by vedla ke snížení ztrát a zvýšení účinnosti. Studovány byly následující způsoby snižování ztrát: snížení odporu statorového vinutí, prodloužení magnetického obvodu, úprava počtu závitů, použití měděné klece, optimalizace tvaru drážek, žíhání plechů a použití plechů s nižšími měrnými ztrátami. Analýza ztrát a studium možností jejich snižování je provedeno experimentálně. Aby bylo možné studovat vliv výše uvedených způsobů snižování ztrát, bylo vyrobeno celkem jedenáct různých vzorků motorů. Výsledky měření a analýzy ztrát těchto vzorků jsou v práci uvedeny. Při řešení práce bylo rovněž využito simulací metodou konečných prvků. Pomocí simulací metodou konečných prvků byl proveden rozbor ztrát analyzovaného motoru, včetně detailů, které nebyly zjištěny pomocí měření, např. rozdělení ztrát v železe mezi rotor a stator. Dále byly simulace metodou konečných prvků využity při analýze vlivu technologie výroby na parametry motoru. V rámci této analýzy byly uvažovány následující vlivy: skutečný tvar magnetického obvodu, nýtování statorového svazku, dopad střihu na vlastnosti materiálu a umístění statorového svazku do elektricky vodivé kostry. Výsledky této analýzy jsou v práci uvedeny.The main objects of this doctoral thesis are analysis of a small induction motor losses and research of ways how to reduce losses and increase efficiency of this motor. The ways how to reduce losses and increase efficiency under study are as follow: reduction of stator winding’s resistance, lengthening of magnetic circuit, modification of turn number, cooper squirrel cage, slots shape optimization, sheets annealing and use of sheets with lower specific losses. The losses analysis and the research of ways how to reduce losses are done due to laboratory work. For this laboratory work, eleven different samples of the motor with above mentioned modifications were manufactured. Results of their measurements and losses analysis are presented in this thesis. There were also simulations by finite elements method used to help solve objects of this thesis. Due to the simulations, analysis of loses of the induction motor under study was done. Results of this analysis include some details that are not included in the results from measurement, for example separation of core losses between rotor and stator. The simulations were also used for analysis of manufacturing technology impact onto the motor’s performance. During this analysis, following impacts were considered: actual shape of magnetic circuit, stator’s sheets riveting, influence of cutting onto material’s properties and placement of the stator into conductive frame. Results of this analysis are presented in this thesis.

Oblivious transfer

Tato práce se zabývá částí asymetrické kryptografie zvané nevšímavý přenos. Naším cílem je přinést ucelený přehled o jednotlivých základních variantách nevšímavého přenosu a popsat konstrukce těchto variant. Součástí práce je zavedení definic potřebných k dokázání bezpečnosti protokolů, které implemtují jednotlivá schémata. Bezpečnost protokolů zkoumáme v téměř poctivém modelu. V práci je informativně vysvětlen Rabinův nevšímavý přenos, ale především jsme se zaměřili na tzv. 1-2, 1-n a m-n varianty nevšímavého přenosu. U každé varianty uvádíme alespoň jedno schéma, pro které jsme dokázali, že je bezpečné. Powered by TCPDF (www.tcpdf.org)This work examines the part of an asymmetric cryptography called an oblivious transfer. Our goal is to bring a comprehensive overwiew about particular variants of an oblivious transfer and to describe construcions of these variants. A component of the work is an introduction of definitions needed for proving the security of protocols which implements the schemes. We are examining the security of protocols in a semi-honest model. There is informatively explained Rabin's oblivious transfer, but we mainly focused on so-called 1-2, 1-n and m-n alternatives of an oblivious transfer. We mention at least one scheme for each alternative, which we have proven that it is secured. Powered by TCPDF (www.tcpdf.org)Katedra algebryDepartment of AlgebraMatematicko-fyzikální fakultaFaculty of Mathematics and Physic

Sentiment and Authority Analysis in Conversational Content

This paper deals with mining conversational content from the social media. It focused on two issues: opinion and emotion classification and identification of authoritative reviewers. The paper also describes applications representing the results obtained in the given areas. Authority identification can be used by organizations to search for experts in their specific areas to employ them. The opinion and emotion analysis can be useful for providing decision-making support

Integrated Alarm System with the access system for Kindergartens

The aim of this article is to design the Integrated Alarm System for the Kindergartens which can handle Alarm, Access and Attendance application by a common system. A similar system is not available on the market yet and there are an opportunity and interest for integrated systems. This article is focused on the kindergartens as a soft target where also Access and Attendance system is needed. Due to this demand, the new concept of the Integrated Alarm System was designed. The main-board consists of three independent microcontrollers where each microcontroller is responsible for one application. The Attendance and Alarm part are prepared for the components which are using the bus connection by the RS-232 or RS-485. The system also has an Ethernet and GPRS interface for outside communication and connection. Each part of the system and the schematic part come with a detailed explanation of the components.Internal Grant Agency of Tomas Bata University [IGA/FAI/2020/003

A monitoring network system and its practical demonstration on a model technological process

In order to deepen students' practical knowledge and understanding of the “Computer Networks” subject, a Monitoring Network System was developed that is able to read, collect and distribute data describing real technological processes. The Monitoring System design is based on Client/Server architecture. The model is represented by the real chemical reactor, which was created for the study of the enzymatic hydrolysis of potentially hazardous chrome-tanned wastes generated during leather manufacturing. Final system should be implemented at the university to the graduates and the system should be modular with possible communication support. The setup of the monitoring system comes with all needed explanation and procedures. © 2018, World Scientific and Engineering Academy and Society. All rights reserved

Systematic Investigation of Novel, Controlled Low‐Temperature Sintering Processes for Inkjet Printed Silver Nanoparticle Ink

Functional inks enable manufacturing of flexible electronic devices by means of printing technology. Silver nanoparticle (Ag NP) ink is widely used for printing conductive components. A sintering process is required to obtain sufficient conductivity. Thermal sintering is the most commonly used method, but the heat must be carefully applied to avoid damaging low-temperature substrates such as polymer films. In this work, two alternative sintering methods, damp heat sintering and water sintering are systematically investigated for inkjet-printed Ag tracks on polymer substrates. Both methods allow sintering polyvinyl pyrrolidone (PVP) capped Ag NPs at 85°C. In this way, the resistance is significantly reduced to only 1.7 times that of the samples on polyimide sintered in an oven at 250°C. The microstructure of sintered Ag NPs is analyzed. Taking the states of the capping layer under different conditions into account, the explanation of the sintering mechanism of Ag NPs at low temperatures is presented. Overall, both damp heat sintering and water sintering are viable options for achieving high conductivity of printed Ag tracks. They can broaden the range of substrates available for flexible electronic device fabrication while mitigating substrate damage risks. The choice between them depends on the specific application and the substrate used