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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.
121

Metamodeling for Business Model Design : Facilitating development and communication of Business Model Canvas (BMC) models with an OMG standards-based metamodel.

Hauksson, Hilmar January 2013 (has links)
Interest for business models and business modeling has increased rapidly since the mid-1990‘s and there are numerous approaches used to create business models. The business model concept has many definitions which can lead to confusion and slower progress in the research and development of business models. A business model ontology (BMO) was created in 2004 where the business model concept was conceptualized based on an analysis of existing literature. A few years later the Business Model Canvas (BMC) was published; a popular business modeling approach providing a high-level, semi-formal approach to create and communicate business models. While this approach is easy to use, the informality and high-level approach can cause ambiguity and it has limited computer-aided support available. In order to propose a solution to address this problem and facilitate the development and communication of Business Model Canvas models, two artifacts are created, demonstrated and evaluated; a structured metamodel for the Business Model Canvas and its implementation in an OMG standards-based modeling tool to provide tool support for BMC modeling.This research is carried out following the design science approach where the artifacts are created to better understand and improve the identified problem. The problem and its background are explicated and the planned artifacts and requirements are outlined. The design and development of the artifacts are detailed and the resulting BMC metamodel is presented as a class diagram in Unified Modeling Language (UML) and implemented to provide tool support for BMC modeling. A demonstration with a business model and an evaluation is performed with expert interviews and informed arguments.The creation of a BMC metamodel exposed some ambiguity in the definition and use of the Business Model Canvas and the importance of graphical presentation and flexibility in the tools used.The evaluation of the resulting artifacts suggests that the artifacts do facilitate the development and communication of the Business Model Canvas models by improving the encapsulation and communication of information in a standardized way and thereby the goals of the research are met.
122

Sustainable Polymer Production: Investigating Synthesis and Copolymerization of Cyclic Ketene Acetals / Hållbar polymerproduktion: Undersökning och syntes samt sampolymerisation av cykliska ketenacetaler

Bourraman, Soufian, Staffas, Stella, Brandt, Adam, Isaksson, Simon January 2023 (has links)
The large amount of non-degradable plastic waste has become a significant environmental concern, leading to an increased need for degradable plastics. Here in, to create degradable polymers, polyesters were produced through radical ring opening polymerization using cyclic ketene acetals. The cyclic ketene acetal monomer 5,6-benzo-2-methylene-1,3-dioxepane has been prepared for the synthesis of homo- and copolymers with methyl methacrylate, α-methylene-γ-valerolactone, α-methylene-γ-butyrolactone, cholesterol methacrylate and limonene acrylate. The polymerization was conducted using radical ring opening polymerization both in bulk and solution polymerization. The structural characteristics of the polymer were determined by different characterization methodologies, including TGA, DSC, SEC, FTIR and 1D 1H-NMR. The results obtained from 1H-NMR analysis showed the composition of the copolymers. TGA analysis revealed the thermal stability of the polymers and their degradation patterns. DSC analysis provided information about the glass transition temperatures (Tg’s) of the polymers. Moreover, the Tg indicated the presence and amounts of comonomers in the copolymers. Overall, the results showed the influence of different comonomers on the properties of the polymers by successfully incorporating the comonomers in the polymer. The thermal properties for polymers containing methyl methacrylate became more thermally stable. The Tg, analyzed with DSC, shifted from the Tg of homopolymers indicating the incorporation of both monomers. The polymers were successfully degraded via hydrolysis in alkaline conditions breaking them down into smaller pieces making them easier to recycle. To conclude, the results all indicate that the incorporation of BMDO and thereby possibly other CKA-monomers into the polymer chains of commonly used plastics could provide valuable tools in the recycling of said plastics.
123

Cultivating Identity and the Music of Ultimate Fighting

Davis, Luke R. 10 July 2012 (has links)
No description available.
124

Metal catalysed alkylation of carbonyl compounds with formaldehyde

Lorusso, Patrizia January 2015 (has links)
Formaldehyde is a chemical used widely in the manufacture of building materials. A remarkable example is represented by the Lucite two-step Alpha technology for the large scale production of methyl methacrylate (MMA), the essential building block of all acrylic-based products. Esters and ketones are important intermediates in the manufacture of acrylate esters therefore α-hydroxymethylenation of carbonyl compounds using formaldehyde as a one carbon alkylating agent and subsequent dehydration to the corresponding methylenated derivatives has been explored in the current work. We report a novel catalytic approach for the synthesis of methyl methacrylate (MMA) via one-pot α-methylenation of methyl propanoate (a chemical intermediate of the ALPHA process) with formaldehyde, generated in situ by Ru-catalysed dehydrogenation of methanol. Elucidation of the mechanism involved in the catalytic dehydrogenation of methanol along with the collateral alcohol decarbonylation reaction was gained through a combined experimental and DFT study. The development of an alternative process where anhydrous formaldehyde is produced in situ would provide a simplification over the current second step of the ALPHA technology where the formaldehyde is initially produced as formalin, subsequently dehydrated to afford anhydrous formaldehyde in order to ensure high selectivity to MMA. As an alternative approach, ketones, in particular 3-pentanone and 2-butanone, were targeted as potential substrates in order to overcome some of the problems related to competing reactions that occur at the ester group. Hydroxymethylenation, followed by dehydration and Baeyer-Villager oxidation, possibly catalysed by enzymes to reverse the normal selectivity, leads to the formation of acrylate esters. The catalytic reaction is enabled by a gold carbene hydroxide complex in such a way that the substrate undergoes C-H activation and the nascent metal alkyl acts as a nucleophile towards the electrophilic formaldehyde, supplied in the form of alcoform* (solution of paraformaldehyde in methanol).
125

Akumulátorový svařovací zdroj / Battery-powered welding inverter

Starec, Stanislav January 2019 (has links)
This master thesis is focused on proposition and following implementation of DC arc welder. This paper is based on semester’s paper, where the first version was realized. The welder is powered by a battery pack with LiFePO4 type cells. Battery cells are protected by BMS circuits. The driving electronics controls the duty cycle step-down (buck) converter in a closed current or power regulation loop. The power regulator has been designed and validated by simulations. Switching power transistors, low side and high side, are implemented by optically isolated gate drivers. Charging the battery is solved by a switching flyback converter. For the charger and the welder is sheet metal construction made of aluminum sheet.
126

Polymere Imidazolin-Isocyanat-Addukte und radikalische Polymerisation von Vinylmonomeren co-initiiert durch 3-substituierte 5-Isoxazolone

Laue, Andreas 19 November 2018 (has links)
Die Arbeit beschreibt neuartige Isocyanat- und Initiierungsreaktionen von speziellen Basen mit dem Imin-Strukturinkrement. Gegenstand des ersten Teils ist die Synthese und Charakterisierung neuer Imidazolin-Isocyanat-Adduksysteme, welche genutzt werden um organische Netzwerke auf der Basis von 1-Ethylimidazolin und diversen Diisocyanaten aufzubauen. Ferner wurden die unterschiedlichen Adduktsysteme hinsichtlich ihrer Anwendbarkeit als blockierte Isocyanate untersucht. Hierzu wurden thermische Analysen wie DSC- und TG-MS-Messungen durchgeführt. Durch experimentelle Ergebnisse und quantenchemische Rechnungen konnte ein neuartiger Reaktionsmechanismus einer Adduktbildung gefunden werden. Die Imidazolin-Isocyanat-Adduktnetzwerke wurden als Macroinitiatoren für die radikalische Polymerisation von Methylmethacrylat (MMA) verwendet, wodurch Adduktnetzwerk-PMMA-Kompositmaterialien erhalten wurden. Gegenstand des zweiten Teils dieser Arbeit ist die Entwicklung eines neuartigen Initiatorsystems für die radikalische Polymerisation von MMA und Styrol, auf der Grundlage der Iminbase-(Meth-)Acrylat-induzierten Polymerisation (IBA-Polymerisation). Hierzu wurden unterschiedlich substituierte Isoxazolone synthetisiert und als Starter für die Polymerisation eingesetzt. Der radikalische Charakter der Polymerisation wurde mittels Copolymerisationsexperimenten belegt.:Abkürzungsverzeichnis 1. Einleitung und Zielsetzung 1.1. Einleitung 1.2. Zielsetzung und Motivation 2. Theoretische Grundlagen 2.1. Isocyanat-Imidazolin-Adduktsysteme als blockierte Isocyanate 2.1.1. Blockierte Isocyanate 2.1.2. Iminbasen-Isocyanat-Addukte 2.2. Radikalische Polymerisation 2.2.2. Autoinitiierung von Styrol und Methylmethacrylat 2.2.3. Definition der IBA- und IBI-Polymerisation 3. Ergebnisse und Diskussion 3.1. Isocyanat-Imidazolin-Adduktsysteme als blockierte Isocyanate 3.1.1. 3 : 1-Isocyanat-Imidazolin-Addukte basierend auf 1-Ethylimidazolin 3.1.2. Organische Netzwerke basierend auf 3 : 1-Isocyanat-Imidazolin-Addukten 3.1.3. 2 : 1-Isocyanat-Imidazolin-Addukte basierend auf 1-Ethyl-2-iso-propyl-imidazolin 3.1.4. 2 : 1-Isocyanat-Imidazolin-Addukte basierend auf 1-Ethyl-2-methyl-imidazolin 3.2. IBA-Polymerisation mittels Isoxazolonen 3.2.1. Tautormerie und thermische Analysen von Isoxazolonderivaten 3.2.2. Polymerisation von Acrylatmonomeren mit Isoxazolonen 3.2.3. Kinetik der IBA-Polymerisation mit Isoxazolonen 3.2.4. IBA-Polymerisation von Styrol mit 3-Phenyl-5-isoxazolon 3.2.5. Mechanistische Studien der IBA-Polymerisation initiiert durch Isoxazolone 4. Zusammenfassung und Ausblick 5. Experimenteller Teil 5.1. Geräte und Chemikalien 5.2. Synthese der Iminbasen 5.3. Synthese der Iminbase–Isocyanat–Addukte 5.4. Synthese der 3 : 1 Adduktnetzwerke 5.5. Synthese von Isoxazolonderivaten 5.6. Polymerisationen von MMA und Styrol mit Isoxazolonen 6. Literatur 7. Anhang Danksagung Lebenslauf Liste an Veröffentlichungen Selbstständigkeitserklärung

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