Technische Universität Bergakademie Freiberg: Qucosa
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Language games and nature: a corpus-based analysis of ecological discourse
Get PDFThis dissertation approaches environmental discourse from the perspective of intercultural communication research. As a discipline, intercultural communication has encompassed a range of analytical levels, from micro-analysis of everyday communicative interactions to the macro-level structural factors that were brought into light by the critical turn. In light of planetary environmental issues, some researchers have called for an “ecological turn” as a new research paradigm. However, the complexity of integrating communication, culture, and the natural world into a coherent research program poses significant conceptual and methodological challenges. This dissertation seeks to provide both a methodological and conceptual framework for discourse at the interface of human cultures and the natural world
Prognose von Aktivierungsparametern für die maschinelle Gewinnung hochfester Gesteine
Get PDFDie maschinelle Gewinnung ist in der Lage, den verantwortungsvollen Umgang mit Lagerstätten und die Sicherheit in Bergwerken zu erhöhen. Dennoch hat sie sich bisher nicht in gekurvten Strecken und in untertägigen Abbauen des Festgesteinsbergbaus etablieren können. Es wird daher überprüft, welche Aktivierungsparameter nötig sind, um den Anwendungsbereich der schrämenden Werkzeuge auf hochfeste Gesteine zu erweitern.
Anhand von sechs Gesteinen werden einerseits die Leistungsfähigkeit des schrämenden Lösens und die Herausforderungen mit zunehmender Festigkeit der Gesteine, andererseits das schlagende Lösen und sein potenzieller Beitrag zur Leistungssteigerung untersucht. Dazu erfolgt die systematische Bestimmung der Gewinnungsparameter und die der gegenseitigen Abhängigkeiten. Am Einzelmeißel werden Orientierung, Schlagenergie, Abstand und Abfolge von Einzelschlägen untersucht, um eine Prognose für günstige Aktivierungsparameter geben zu können.
Die Ergebnisse fließen in das Rechenmodell eines rotierenden Gewinnungsorgans, das die Spanleistung und wichtige Parameter der Gewinnung wahlweise mit oder ohne Aktivierung bestimmt. Der darauffolgende Vergleich der beiden Konzepte ermittelt anhand von zwei Gesteinen die jeweilige Vorzugsvariante
Thermodynamic modelling as applied to the development of TRIP-Matrix-Composite materials: The Fe–Mg–Mn–Ti–Zr–O system
Get PDFThis thesis performed within the Collaborative Research Center 799 describes a development of the metal-ceramic thermodynamic databases as applied to the design of the TRIP-Matrix-Composite materials. A wide range of theoretical and experimental investigations have been carried out in the relevant systems of Fe–Mg–Zr–O, Mg–Ti–Zr–O and Mg–Mn–Zr–O. Thermodynamic data were obtained using experimental methods of calorimetry and ab-initio calculations. Phase relations in the constituent binary and ternary systems have been studied using different types of static and dynamic methods. The obtained results allowed an assessment of thermodynamic parameters of the aforementioned systems using CALPHAD approach. The thermodynamic calculations have been performed to predict interfacial reactions within the composite material as well as to made recommendations for the design and further development of production processes for TRIP-Matrix-Composite materials
Durchströmungswäsche von Filterkuchen aus Partikeln mit innerer Porosität
Get PDFDie Durchströmungswäsche von Filterkuchen aus innenporösen Partikeln wird anhand von makro- und mesoporösen Kieselgelen untersucht. Die Filterkuchenbildung der KCl-haltigen Suspensionen erfolgt in einer Drucknutsche nach VDI-2762-2. Die Filterkuchen werden über einen perforierten Stempel mit entionisiertem Wasser durchströmt und der Wascherfolg über die Bilanzierung der K+-Ionen ermittelt. Die Porosität der Kieselgel-Filterkuchen beträgt 80 %, wobei sich 50 % der gesamten Mutterlauge in den Innenporen befindet. Dennoch zeigen sich mit 1 % Restbeladung ähnliche Waschergebnisse wie für unporöse Feststoffe (Quarz und Glas). Die Innenporen werden gereinigt, der in der Literatur postulierte ausgeprägte Diffusionsbereich in der Waschkurve wird nicht sichtbar. Berechnungen nach CARMAN-KOZENY, FICK und mittels dimensionsloser Kennzahlen verdeutlichen, dass Perfusion und Diffusion die Wäsche poröser Systeme beeinflussen. Die vorgestellten Modelle eignen sich auch für die Anwendung in der Praxis.The displacement washing of filter cakes consisting of porous particles is investigated using macro- and mesoporous silica gels. The filter cakes of KCl-containing suspensions are formed in a pressure filter device according to VDI-2762-2. The filter cakes are flown through with deionized water via a perforated piston and the washing success is determined by balancing the K+ ions. The porosity of the silica gel filter cakes is 80 % and 50 % of the mother liquor is trapped in the inner pores. Nevertheless, with 1 % residual loading, washing results are similar to those for non-porous solids (quartz, glass). The inner pores are cleaned, the distinct diffusion region in the washing curve postulated in the literature is not visible. Calculations according to CARMAN-KOZENY, FICK and by means of dimensionless quantities illustrate that both perfusion and diffusion influence the washing of porous systems. The presented models are also suitable for practical applications
Thermomechanische und schädigungsmechanische Modellierung von hochlegierten TRIP-Stählen
Get PDFDie Arbeit widmet sich der Entwicklung und numerischen Implementierung eines nichtlokalen kontinuumsmechanischen Schädigungsmodells zur Beschreibung des duktilen Versagens eines austenitischen TRIP-Stahlgusses. Dieser weist eine martensitische Phasenumwandlung während der Verformung auf. Das Umwandlungs- und Verfestigungsverhalten des Untersuchungswerkstoffs hängt stark von Temperatur und Spannungszustand ab. Deshalb wird ein vollständig thermomechanisch gekoppeltes Viskoplastizitätsmodell zugrunde gelegt, welches die temperaturabhängige Zug-Druck-Asymmetrie von Verfestigung und verformungsinduzierter Martensitentwicklung abbildet. Bei erhöhter Dehnrate können experimentell beobachtete Kreuzungseffekte der Fließkurven vorhergesagt werden. Die Schädigungsmodellierung baut auf dem viskoplastischen Grundmodell auf, wobei das netzunabhängige Verhalten durch eine Gradientenerweiterung im Rahmen der mikromorphen Theorie erreicht wird. Im Modell können verschiedene Ansätze für Schädigungsinitiierung und -entwicklung kombiniert werden. Die Einflüsse der Modellparameter auf die Ergebnisse von Risswachstumssimulationen werden für ausgewählte Modellvarianten untersucht und bewertet. Mithilfe erarbeiteter Kalibrierungsstrategien können die qualifizierten Varianten erfolgreich an experimentelle Ergebnisse von Kerbzugversuchen und bruchmechanischen Kompaktzugproben angepasst werden.The present thesis comprises the development and numerical implementation of a non-local damage model in order to describe ductile failure of a cast austenitic TRIP-steel. The TRIP-steel shows a martensitic phase transformation during deformation. The transformation and strain hardening behavior is strongly dependent on temperature and stress state. For this reason, a fully thermomechanically coupled viscoplasticity model is proposed, which exhibits the temperature dependent tension-compression-asymmetry of strain hardening and deformation-induced martensite evolution. Experimentally observed crossing effects of the flow curves can be predicted at increased strain rates. The damage modeling is based on the viscoplastic basic model, whereby the mesh-independent behavior is achieved by a gradient extension within the framework of micromorphic theory. Different approaches for damage initiation and evolution can be combined within the model. The influences of the model parameters on results of crack growth simulations are investigated and evaluated for selected model variants. With the help of developed calibration strategies the qualified variants can be successfully adapted to experimental results of notched tensile tests and compact tension tests
On the design of aluminum-based complex hydride systems for chemical hydrogen storage
Get PDFThe present study focuses on the development of Al-based systems and their examination as a medium for reversible hydrogen uptake. The first part of this thesis is dedicated to the chemistry and properties of Al-N-based materials. The synthesis, characterization, and detailed thermal decomposition studies of several aminoalanes have been described. As a result, single-crystal X-ray diffraction analyses revealed two new crystal structures of piperidinoalanes. The perspective approach employing activated aluminum and piperidine for reversible hydrogen uptake has been established. The second part of this work was focused on the modification of the properties of NaAlH4-based systems in order to generate the material with the high dissociation pressure suitable for high-pressure tank technologies. Considerable progress has been achieved in improving the hydrogen sorption properties by adding the extra aluminum powder to the Ti-catalysed NaAlH4-based system. Thus, the present study contributes to the understanding of the hydrogen sorption behavior of Al-based systems with perspectives being applicable to other related materials.:DECLARATION
ACKNOWLEDGEMENTS
DEFINITIONS AND ABBREVIATIONS
ABSTRACT
CONTENTS
LIST OF TABLES
LIST OF FIGURES
MOTIVATION AND GOALS
1 INTRODUCTION
1.1 The prospects for hydrogen-based energy systems
1.2 Requirements for the hydrogen storage system
1.3 An overview of hydrogen storage strategies
1.4 Complex hydrides as a promising hydrogen storage materials
1.4.1 Metal borohydride systems
1.4.2 Alanate-based systems
1.4.3 Nitrogen-containing complex hydrides
1.5 Summary
2 GENERAL CHARACTERIZATION METHODS
2.1 X-ray crystallography
2.1.1 X-ray powder diffraction (XRPD)
2.1.2 Single-crystal structure analysis
2.2 Thermal analysis
2.3 Quantitative chemical analysis
2.3.1 Elemental analysis
2.3.2 Inductively coupled plasma optical emission spectrometry (ICP-OES)
2.4 Nuclear magnetic resonance spectroscopy (NMR)
3 LIQUID-STATE HYDROGEN STORAGE
3.1 State of the art
3.1.1 Liquid-state hydrogen storage materials
3.1.2 Al-N-based compounds as potential materials for hydrogen storage
3.1.3 Summary
3.2 Materials preparation and experimental details
3.2.1 Chemicals and sample handling
3.2.2 Synthesis of aminoalane in diethyl ether solution with aluminum hydride
3.2.3 Preparation of activated aluminum
3.2.4 Direct hydrogenation of activated aluminum supported by amine
3.3 Results and discussion
3.3.1 Is the solid-state hydrogen storage in aminoalanes possible?
3.3.2 Optimization of the direct hydrogenation of activated aluminum supported by amine
3.3.2.1 Synthesis and characterization of triethylenediamine alane complex
3.3.2.2 Synthesis of aminoalanes via direct hydrogenation of activated aluminum and N-heterocyclic amine
3.3.3 Investigation of piperidinoalanes for reversible hydrogen uptake
3.3.3.1 Crystal structure determination of piperidinoalanes
3.3.3.2 Influence of the initial reaction parameters on the piperidinoalane formation
3.3.3.3 Reversible hydrogenation in piperidinoalane system
3.3.4 Conclusions
4 SOLID-STATE HYDROGEN STORAGE
4.1 State of the art
4.1.1 Thermodynamic tuning of the hydrides
4.1.2 Features of the sodium alanate system
4.1.3 Catalytic enhancement of reversible hydrogenation in sodium alanate
4.1.4 The relevance of the Al-TM species in doped sodium alanate
4.1.5 Summary
4.2 Materials preparation and experimental details
4.2.1 Chemicals and purification procedure
4.2.2 Activation procedure of sodium alanate via mechanochemical treatment
4.2.3 Pressure-composition-isotherm measurements with a Sieverts-apparatus
4.2.4 High-pressure differential scanning calorimetry investigation of sodium alanate samples
4.3 Results and discussion
4.3.1 Tailoring the properties of sodium alanate-based system with the help of Ti-additive
4.3.2 Influence of the aluminum addition on the sorption behavior of Ti-doped sodium alanate
4.3.3 High-pressure DSC study of hydrogen sorption properties of doped sodium alanate system
4.3.4 Conclusions
5 SUMMARY AND CONCLUSIONS
RECOMMENDATIONS AND OUTLOOK
REFERENCES
SUPPORTING INFORMATION
Appendix A
Appendix B
Appendix C
Publication
Sol-Gel Derived Hydroxyapatite Coatings for Titanium Implants: a review
Get PDFWith the growing demands for bone implant therapy, titanium (Ti) and its alloys are considered as appropriate choices for the load-bearing bone implant substitutes. However, the interaction of bare Ti-based implants with the tissues is critical to the success of the implants for long-term stability. Thus, surface modifications of Ti implants with biocompatible hydroxyapatite (HAp) coatings before implantation is important and gained interest. Sol-gel is a potential technique for deposition the biocompatible HAp and has many advantages over other methods. Therefore, this review strives to provide widespread overview on the recent development of sol-gel HAp deposition on Ti. This study shows that sol-gel technique was able to produce uniform and homogenous HAp coatings and identified the role of surface pretreatment of Ti substrate, optimizing the sol-gel parameters, substitution, and reinforcement of HAp on improving the coating properties. Critical factors that influence on the characteristics of the deposited sol-gel HAp films as corrosion resistance, adhesion to substrate, bioactivity, morphological, and structural properties are discussed. The review also highlights the critical issues, the most significant challenges, and the areas requiring further research
Magmatic-Hydrothermal Events, Mineralogy and Geochemistry of Tourmaline Breccia in the Giant Río Blanco – Los Bronces Porphyry Copper Deposit, Central Chile
Get PDFThe Río Blanco–Los Bronces (Chile) is one of the richest endowed porphyry copper-molybdenum districts worldwide, where about 20% of the known mineralization is hosted by tourmaline-cemented hydrothermal breccia.
This work seeks: (1) to find a relationship between tourmaline chemical and/or isotopic composition and the degree of mineralization in the breccia, (2) to constrain the source of the mineralizing fluid in the breccia, and (3) to determine of the composition and age of intrusive units in three new exploration projects and correlate them with the known intrusive rocks of the mine areas. Tourmaline from mineralized and barren breccias has similar boron isotopic compositions but differences in Mg/(Mg+Fe) ratios, Al-contents and Al-Fe correlation, which may have exploration value. Boron and sulfur isotopes results are consistent with a magmatic source of hydrothermal fluids. Results of whole rock geochemistry and U-Pb and 40Ar/39Ar geochronology of intrusive units, breccia and late-stage veins are combined with previous U-Pb, Ar/Ar and Re-Os ages to elucidate the magmatic and hydrothermal history of the district.:1 Introduction
1.1 Motivation of the study and statement of research questions
1.2 Scope of the study
2 Porphyry copper deposits (PCDs)
2.1 Introduction
2.1.1 Global copper inventory
2.1.2 Definition and classification of PCDs
2.2 Regional scale characteristics of PCDs
2.2.1 Tectonic setting
2.2.2 Space and time distribution
2.2.3 Porphyry stocks and their pluton and volcanic connections
2.2.4 Wall-rock Influence
2.3 Deposit-scale characteristics
2.3.1 Porphyry stocks and dikes
2.3.2 Hydrothermal breccia
2.3.3 Alteration-mineralization zoning
2.4 Processes of PCD formation
2.4.1 Arc magmatism
2.4.2 Magmatic volatiles
2.4.3 Genetic models
3 Regional setting of the study area
3.1 Tectono-magmatic setting
3.2 Metallogenic belts
4 Río Blanco – Los Bronces mining district
4.1 Mining history
4.2 District geology
4.2.1 Stratified rocks
4.2.2 Plutonic and hypabyssal intrusions
4.2.3 Structures
4.2.4 Alteration and mineralization
4.2.1 Geochronology database
5 Results
5.1 Plutonic units
5.1.1 Petrography
5.1.2 Whole rock (WR) geochemistry
5.1.3 Geochronology
5.2 Mineralization
5.2.1 Petrography
5.2.2 Tourmaline occurrence and composition
5.2.3 Sulfides and sulfates
6 Discussion
6.1 Time-space relationships of intrusion, brecciation and hydrothermal alteration
6.2 Stable isotope constraints on fluid source and evolution
6.2.1 Oxygen, hydrogen and sulfur isotopes
6.2.2 Boron isotopes
6.3 Tourmaline as a redox indicator and significance for exploration
7 Summary and conclusions
8 References
Digital supplement
Appendix (Methods)
9 Appendix Methods
9.1 Optical microscopy (OM)
9.2 Scanning electron microscope (SEM) and energy-dispersive X-ray spectroscopy (EDS)
9.3 Whole rock chemical analysis
9.4 Electron microprobe analyses (EMPA)
9.5 Boron isotopes
9.6 Sulfur isotopes
9.7 40Ar/39Ar dating
9.8 Zircon separation and characterization
9.9 U-Pb zircon LA-ICP-MS dating
9.10 U-Pb zircon CA-ID-TIMS dating
9.11 Single zircon evaporation as screening metho
Hydrodynamical investigations of liquid ventilation by means of advanced optical measurement techniques
Get PDFAlthough liquid ventilation has been researched and studied for the last six decades, it did not achieve its expected optimal performance. Within this work, a deeper understanding of the fluid dynamics during liquid ventilation shall be gathered to extend the already available clinical knowledge about this ventilation strategy. In order to reach this goal, advanced optical flow measurement techniques are applied in different models of the human conductive airways to obtain global velocity fields, identifying prominent flow structures and to determine important dissolved oxygen transport paths. As the velocity measurements revealed, the evolving flow field is strongly dominated by secondary flow effects and is highly dependent on the local airway geometry. During the visualization experiments of the dissolved oxygen concentration fields, different transportation paths occur at inspirational and expirational flow. The initial concentration distribution can be linked to the underlying flow fields but decouples after the peak velocity phases. With higher flow rates/ tidal volumes, a more homogeneously distributed oxygen concentration can be reached.:List of Figures ....................................................................................... VII
List of Tables ........................................................................................XIII
Nomenclature ........................................................................................ XV
1 Introduction......................................................................................... 1
1.1 Motivation ........................................................................................1
1.2 Research objectives........................................................................... 3
1.3 Outline............................................................................................ 4
2 State of the art .................................................................................... 5
2.1 Liquid Ventilation............................................................................. 5
2.2 In vitro modeling.............................................................................. 8
2.3 Flow measurements ......................................................................... 11
2.4 Gas transport..................................................................................13
3 Flow field measurements ................................................................... 16
3.1 Hydrodynamic Model.......................................................................16
3.1.1 Lung replica ..........................................................................16
3.1.2 Flow parameter .....................................................................18
3.1.3 Limitations ...........................................................................22
3.2 Particle Tracking Velocimetry (PTV) ................................................24
3.2.1 Measurement principle ...........................................................24
3.2.2 Double-frame 2D-PTV ...........................................................25
3.2.3 Time-resolved 3D-PTV ..........................................................28
3.2.4 Phase-locked ensemble PTV ................................................... 31
3.3 Experimental set-up and measurement procedure ...............................33
3.3.1 Lung flow facility...................................................................33
3.3.2 2D-PTV configuration............................................................36
3.3.3 3D-PTV configuration............................................................36
3.4 Results & Discussion........................................................................38
3.4.1 Artificial lung........................................................................38
3.4.2 Realistic lung ........................................................................52
3.5 Conclusion ......................................................................................59
4 Oxygen transport ...............................................................................61
4.1 Hydrodynamic Model....................................................................... 61
4.1.1 Lung replica .......................................................................... 61
4.1.2 Flow parameter .....................................................................62
4.1.3 Limitations ...........................................................................65
4.2 Oxygen Sensitive Dye ......................................................................66
4.3 Experimental set-up......................................................................... 71
4.4 Results & Discussion........................................................................75
4.4.1 Constant flow rate .................................................................75
4.4.2 Oscillatory flow .....................................................................83
4.5 Conclusion ......................................................................................90
5 Summary............................................................................................ 92
6 Outlook .............................................................................................. 95
Bibliography ............................................................................................ 97Trotz intensiver Forschung in den letzten sechs Jahrzehnten, befindet sich die Flüssigkeitsbeatmung immernoch weit entfernt vom klinischen Alltag. Mit dieser Arbeit soll ein Beitrag geleistet werden, um das Wissen um die strömungsmechanischen Effekte während der Flüssigkeitsbeatmung zu vertiefen. Dazu werden verschiedene Modellexperimente durchgeführt, bei welchen moderne laseroptische Strömungsmessmethoden zum Einsatz kommen. Untersucht werden dabei unterschiedlich komplexe Geometrien der leitenden menschlichen Atemwege mit dem Ziel wesentliche Strömungsstrukturen, globale Geschwindigkeitsfelder und wichtige Transportwege des gelösten Sauerstoffs zu identifiziern. Die Geschwindigkeitsmessungen zeigen ein stark durch sekundäre Strömungseffekte dominiertes Geschwindigkeitsfeld, welches wesentlich von der lokalen Geometrie abhängig ist. Durch die qualitative und quantitative Erfassung der gelösten Sauerstoffkonzentrationsfelder können wichtige Transportwege aufgedeckt werden.
Diese unterscheiden sich deutlich zwischen inspiratorischer und expiratorischer Strömungsrichtung. Die initialen Konzentrationsfelder stimmen mit den unterliegenden Geschwindigkeitsfeldern überein, unterscheiden sich ab der verzögernden Strömungsphase jedoch. Höhere Volumenströme/Tidalvolumen tragen dabei zu einer gleichmäßigeren Konzentrationsverteilung bei.:List of Figures ....................................................................................... VII
List of Tables ........................................................................................XIII
Nomenclature ........................................................................................ XV
1 Introduction......................................................................................... 1
1.1 Motivation ........................................................................................1
1.2 Research objectives........................................................................... 3
1.3 Outline............................................................................................ 4
2 State of the art .................................................................................... 5
2.1 Liquid Ventilation............................................................................. 5
2.2 In vitro modeling.............................................................................. 8
2.3 Flow measurements ......................................................................... 11
2.4 Gas transport..................................................................................13
3 Flow field measurements ................................................................... 16
3.1 Hydrodynamic Model.......................................................................16
3.1.1 Lung replica ..........................................................................16
3.1.2 Flow parameter .....................................................................18
3.1.3 Limitations ...........................................................................22
3.2 Particle Tracking Velocimetry (PTV) ................................................24
3.2.1 Measurement principle ...........................................................24
3.2.2 Double-frame 2D-PTV ...........................................................25
3.2.3 Time-resolved 3D-PTV ..........................................................28
3.2.4 Phase-locked ensemble PTV ................................................... 31
3.3 Experimental set-up and measurement procedure ...............................33
3.3.1 Lung flow facility...................................................................33
3.3.2 2D-PTV configuration............................................................36
3.3.3 3D-PTV configuration............................................................36
3.4 Results & Discussion........................................................................38
3.4.1 Artificial lung........................................................................38
3.4.2 Realistic lung ........................................................................52
3.5 Conclusion ......................................................................................59
4 Oxygen transport ...............................................................................61
4.1 Hydrodynamic Model....................................................................... 61
4.1.1 Lung replica .......................................................................... 61
4.1.2 Flow parameter .....................................................................62
4.1.3 Limitations ...........................................................................65
4.2 Oxygen Sensitive Dye ......................................................................66
4.3 Experimental set-up......................................................................... 71
4.4 Results & Discussion........................................................................75
4.4.1 Constant flow rate .................................................................75
4.4.2 Oscillatory flow .....................................................................83
4.5 Conclusion ......................................................................................90
5 Summary............................................................................................ 92
6 Outlook .............................................................................................. 95
Bibliography ............................................................................................ 9
Einsatz biogener Kraftstoffe zur Senkung der Emissionen von stationären Verbrennungsmotoren
Get PDFDiese Arbeit beschäftigt sich mit dem Einsatz biogener Ersatzbrennstoffe bei der motorischen Verbrennung.
Zum einen wurden die laminaren Brenngeschwindigkeiten von Ethanol und iso-Butanol sowie Gemischen mit iso-Oktan bestimmt. Es konnten Messwerte für die Validierung von numerischen Mechanismen sowie Parameter für die Abbildung der Temperatur- und Druckabhängigkeit der Brenngeschwindigkeit bestimmt werden. Der Vergleich der Messverfahren zeigt eine gute Übereinstimmung.
Zum anderen wurden die Auswirkungen der Beimischung von Wasserstoff auf die Abgaszusammensetzung und den Wirkungsgrad an einem Verbrennungsmotor ermittelt. Die Erhöhung des Wasserstoffanteils führt zur Erhöhung des Wirkungsgrades. Die Abgasbestanteile Kohlenstoffmonoxid, Formaldehyd und Methan werden reduziert, während Stickoxide zunehmen. Mit den begleitenden Simulationen kann gezeigt werden, dass höhere Wasserstoffanteile die Oxidation durch einen erhöhten Anteil an OH-Radikalen begünstigen. Der Grund für das verstärkte Auftreten von Stickstoffmonoxid liegt in der Verlängerung der Verweilzeit der verbrannten Gase in der Oxidationszone