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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.
21

Možnosti využití netradičních surovin pro výrobu vakuových tepelných izolací s extrémě nízkou hodnotou tepelné vodivosti / Possibilities of use of non traditional raw materials for the manufacture of the vacuum thermal insulation with extremely low thermal conductivity

Kováriková, Růžena January 2018 (has links)
The thesis deals with the study of the behavior of advanced insulating materials on the basis of secondary raw materials and the possibilities of their use in the production of vacuum insulation using in the construction and industry. The work will be devoted to possible raw material resources, problems of long-term behavior of insulators on the basis of selected secondary raw materials under reduced pressures as well as economic evaluation of the competitiveness of alternative insulators on the building market in the field of vacuum insulation.
22

Membránový lis / Diaphragm Press

Krčál, Zdeněk January 2010 (has links)
The aim of this thesis is constructional concept of diaphragm press for thermoplastic forming. The press consists of two chambers. First chamber is designed for forming of semi-finished product to forming temperature and second chamber is designed for heating the semi-finished product. Theoretical part of this thesis is focused on technologies in use and shaping of plastic description. Practical part of this thesis deals with detailed description of press concept including consistence calculations and drive units calculations. The whole concept, including its individual parts, is designed using the Autodesk Inventor software. At the end of this thesis, there is the economic and safety analysis.
23

Bajonetový uzávěr dveří přetlakové pece / Bayonet door of pressurized furnace

Brada, Karel January 2011 (has links)
In this master's thesis a design of door for helium quenching furnace is described. Based on background research, several options for the design have been compared. All calculations were carried out based on structural needs resulting from high pressure gas quenching technology. By the ending of this thesis a mounting procedure and rough cost price estimation is described. Part of master's thesis is also a virtual 3D prototype and a drawing documentation.
24

Oduhličení a odplynění vysokolegovaných chromových ocelí ve vakuu / Decarburisation and degassing of high-alloyed Cr steels under vacuum

Ertelt, Tomáš January 2014 (has links)
The work deals with the investigation of the effects of vacuum degassing and decarburization in high alloyed stainless steel. The reason for this is to increase corrosion resistance and mechanical properties. The theoretical part is devoted to the analysis of options to reduce carbon, nitrogen, hydrogen and manganese at atmospheric pressure and in vacuum. In experimental part there is the description of melting, calculation of conditions facilitating reduction of oxide inclusions as a function of the gas pressure in the furnace and the evaluation of the influence of vacuum on the content reduction of carbon, nitrogen and manganese.
25

En Jämförelse Mellan Rheogjutning Och Konventionell Pressgjutning Med Vakuum. : Vid Tillverkning Av Aluminiumkomponenter.

Ling Brännlund, Marisa, Martinsson, Hanna January 2021 (has links)
The car industry is constantly under pressure to be competitive in their product development which includes not only safety and increased performance, but also in their environmental impact. Volvo Cars strives to be more environmental and high performing in their product development, which of course includes manufacturing methods since these highly effect a components environmental impact and mechanical performance. To optimize these aspects of car components it is important to have good knowledge of current manufacturing processes and the possibilities and challenges that come with them and their relationship to already well-established processes. This report focuses on the relatively new RheoMetal-process (called rheocasting in this report), a process that uses a partly solidified slurry to fill the mold, and the conventional high pressure die casting (HPDC) which uses a liquid melt, and their differences in casting aluminum-alloys from both a process-and design perspective. The RheoMetal-process is also compared to a few other semi-solid processes on the market, thixocasting, GISS and SEED. This report is meant to work as a foundation for product developers at Volvo Cars to learn about rheocasting, and eventually use to make future choices for manufacturing processes for aluminum alloys. With a literature review, interviews with experts and professionals and analysis of casting simulations, information of the processes and their effect on material properties was collected and compiled. What could be concluded from these methods was that the slurry in the RheoMetal process has a globular microstructure, unlike the melt in HPDC which is dendritic. The globular microstructure in rheocasting is caused from shearing the slurry which makes it run more easily. The thicker consistency of the slurry makes the flow more laminar when filling a mold which makes for less air entrapment and defects in the material. The reduced number of defects opens the possibility of using T6 heat treatment on rheocasted components to reach improved mechanical properties, which would normally not be recommended for components made with HPDC. The globular microstructure makes the slurry flow easier which means, in combination with less defects, thinner components can be cast with similar strength as thicker components made with HPDC. This would contribute to weight reduction in a car, and in turn less fuel consumption. With rheocasting, a wider range of alloys can be used because of the ability of using non-eutectic alloys for the slurry. From research and analysis of simulations it could also be concluded that a combination of a high solid phase fraction and low gate velocity result in a more laminar flow and therefore fewer porosities in the final component.
26

Felsäkring & effektivisering av slipningsprocessen vid tillverkning av tätningsmoduler

Jonasson, Petter, Kallenberg, Pontus January 2023 (has links)
No description available.
27

Vakuum: Theorie oder Modell? Leere oder Fülle?

Reichelt, Uwe J. M. 12 March 2024 (has links)
In dieser Arbeit wird untersucht, ob es möglich ist, mit den Mitteln der Theoretischen Physik mehr auszusagen über das, was sich unter dem Vakuum, aus dem der Urknall erfolgte, verstehen lässt. Hierbei wird deutlich, dass es sich nicht mehr um eine Theorie im eigentlichen Sinne, also um widerlegbare Aussagen handeln, sondern stattdessen um eine Art Modell, das nur anhand von Indizien auf seine Tauglichkeit geprüft werden kann, indem z. B. bisher unbekannte Vorhersagen bestätigt werden oder nicht. Eine solche bisher unbekannte fundamentale Aussage ist, dass dieses Modell zum Ergebnis hat, Schwarze Riesenlöcher entstehen mit dem Freisetzen Dunkler Materie als erstes nach dem Urknall und sind für die Strukturierung des Universums maßgeblich. Beim Begründen dieses Modells wird auf die Methodik in der Veröffentlichung über die mögliche Anatomie Schwarzer Löcher zurückgegriffen. Allerdings konnte in jener Arbeit die mathematische Möglichkeit des Vakuums lediglich als Existenz zweier Antipoden, Energie und Dunkler Energie, am gleichen Ort genannt, aber kein physikalischer Weg dazu aufgezeigt werden. Dort hieß es „Zur Erklärung des Vakuumzustands sehe ich keine Möglichkeit, weil er durch den simplen Zusammenhang, dass gleichviel Energie beider Arten am gleichen Ort sich gegenseitig auslöschen, also von jeder der beiden Energiearten einzeln aus betrachtet praktisch nicht mehr vorhanden ist, mathematisch geradezu trivial, aber physikalisch nicht erklärbar scheint.“ Hier wird nun eine mögliche physikalische Lösung aufgezeigt, die aber ein Entstehen der G-Bosonen erst nach dem Urknall, wie dort noch angenommen, ausschließt. Jetzt muss vielmehr angenommen werden, dass die G-Bosonen bereits im Vakuum existieren und als Dunkle Materie der Gegenpart zur Dunklen Energie sind. Es wird gezeigt, dass sehr wohl zwei sich vollständig kompensierende Dinge, die sich auch noch abstoßen, dennoch einen stabilen Zustand haben können und alle Eigenschaften, die physikalisch von einem Vakuum erwartet werden, erfüllen. Der Preis für diese theoretische Betrachtung ist leider, dass dabei aus den technischen Grenzen unserer Zivilisation heraus experimentell nicht mehr nachprüfbare Aussagen gemacht werden und Nachprüfungen der Theorie nur noch über astronomisch und astrophysikalisch ermittelte Bestätigungen oder Widerlegungen in Form von Indizien Hinweise geben können.:1. Abstract 2. Einleitung 3. Vorbetrachtung 4. Das Kräftegleichgewicht im lichtschnellen Fall 4.1 Gleichgewichtsverhalten lichtschneller Energie, Dunkler Materie 4.2 Gleichgewichtsverhalten Dunkler Energie 4.3 Gleichgewichtsverhalten Dunkler Energie im Gravitationsfeld von lichtschneller Energie bzw. Dunkler Materie 4.4 Gleichgewichtsverhalten lichtschneller Energie im Gravitationsfeld von Dunkler Energie 4.5 Zusammenfassung 5. Das Vakuum 6. Der Urknall 7. Der philosophische Aspekt 8. Astronomische Befunde 9. Schlussbetrachtung
28

Konstrukční návrh precizního manipulátoru / Conceptual design of a precision manipulator

Stuchlík, Petr January 2018 (has links)
This diploma thesis deals with the problems of analysis and the subsequent design of a precision manipulator used as a microscope table. The first part od the final thesis deals with the problems associated with the movement of the test sample within the electron microscope. Subsequently, possiblle design variants were proposed, further developing the next steps fot the correctness and functionality of manipulator. The individual force loads of the components were calculated. The result of the work was constructed as a CAD model with subsequent transfer to the assembly drawing.
29

Návrh technologie výroby tělesa světlometu motocyklu / Design of manufacturing technology for motorcycle headlamp body

Nosek, Jan January 2010 (has links)
The thesis is a proposal technology of the main body of motorcycle polymer material from Bayer's APEC - high temperature polycarbonate 1703. Literary study summarizes findings from a thermoplastic injection molding technology and the possibilities of structural design of injection molds, plastic plating technology from a focus on the most important technology in the field of lighting technology vehicles. Given the anticipated production run of 50 thousand. pieces are assessed a total of 2 variants of the molding parts. The practical part was modeled and specified product designed mold. Construction was done by using SolidWorks 2007 software and normalities FCPK Bytów and HASCO. For the selected option is implemented technological calculations. For the proposed technology was chosen Allrounder injection molding machine 570 A the manufacturer Arburg designed and suitable technological process of production.
30

Návrh nosné platformy pro nízkoteplotní UHV STM mikroskop / Design of the supporting platform for low temperature UHV STM microscope

Dao, Tomáš January 2014 (has links)
Diploma thesis deals with the design of a vibration isolated platform for low temperature scanning tunneling microscope working under ultra high vacuum (UHV STM). Cooling of the microscope is done by liquid helium using a flow cryostat designed in Institute of Scientific Instruments of the AS CR. In the thesis, general requirements of designing of an ultra high vacuum compatible devices are discussed, as well as the ways of vibrational isolation and damping. Also some ways how to restrict the transfer of vibration between vacuum devices and surroundings are mentioned. This knowledge is then applied to the design of the antivibrational microscope platform compatible with low temperature usage. For better understanding of vibrational transfer and damping, a real model of the designed platform is made and vibrational transfer characteristics are measured and compared with the theory.

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