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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Návrh manipulátoru pro TEM / Design of manipulator for TEM

Melichárek, Václav January 2020 (has links)
The topic of this master’s thesis is the design of a sample manipulator for TEM. Regarding which the segment of the sample manipulator used to move the sample in the direction of the x-axis (so-called x-stage) was designed. The introductory theoretical part is concerned with a brief description of transmission electron microscopy focused on the imaging methods used in TEM and the procedures of preparing and loading TEM samples. The theoretical part follows with the design of precise mechanisms, especially with respect to the inaccuracies of their operation and the technological aspect of the design. In the practical part, a detailed analysis of the design of the x-stage is presented. Kinematics and dynamics of the mechanism is analyzed in depth, following with the description of the overall design of the mechanism and some of its parts in detail.
2

Beitrag zur Analyse von Disklinationsstrukturen in plastisch verformten Metallen

Motylenko, Mykhaylo 09 April 2010 (has links)
Gegenstand der Arbeit ist die Analyse der bei hohen Verformungsgraden in Werkstoffen durch kollektive Bewegung der Versetzungen entstandenen neuen Defektkonfigurationen, die auf der mesoskopischen Skala agieren. Diese so genannte Disklinationen rufen neben starken Gitterdehnungen auch erhebliche lokale Gitterrotationen hervor. Es wurde der Nachweis der Existenz der Disklinationen in plastisch verformten Kristallen geliefert sowie die qualitative und quantitative Analyse der Disklinationskonfigurationen und der Disklinationsstärke durchgeführt. Die Untersuchungen an stark verformten Ein- und Vielkristallen wurden mittels sowohl lokalen Methoden der Transmissions- (TEM, CBED) und Rasterelektronenmikroskopie (REM, EBSD) als auch der integralen Methoden der Röntgenstrukturanalyse (XRD) durchgeführt. Die Ergebnisse haben gezeigt, dass die Entwicklung der Zellblockstruktur mit erheblichem Anstieg der Desorientierungen und Versetzungsdichten in Versetzungswänden verbunden ist und durch die Bildung der Netzwerke von Disklinationen gefördert wird.
3

Preparation and characterization of polyethylene based nanocomposites for potential applications in packaging

Gill, Yasir Q. January 2015 (has links)
The objective of my work was to develop HDPE clay nanocomposites for packaging with superior barrier (gas and water) properties by economical processing technique. This work also represents a comparative study of thermoplastic nanocomposites for packaging based on linear low density polyethylene (LLDPE), high density polyethylene (HDPE) and Nylon12. In this study properties and processing of a series of linear low density polyethylene (LLDPE), high density polyethylene (HDPE) and Nylon 12 nanocomposites based on Na-MMT clay and two different aspect ratio grades of kaolinite clay are discussed.

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