Technische Universität Bergakademie Freiberg: Qucosa
Not a member yet
1431 research outputs found
Sort by
(3,5-Dimethyl-1H-pyrazol-1-yl)trimethylsilane
Get PDFThe title compound, C8H16N2Si, crystallizes in the the orthorhombic space group P212121 with one molecule in the asymmetric unit. The Si—N bond is 1.782 (2) Å, which is substantially longer than is found in comparable (3,5-dimethylpyrazolyl)silanes. The trimethylsilyl group adopts a staggered conformation with respect to the planar 3,5-dimethylpyrazolyl unit. C—H⋯N hydrogen bonds between neighboring molecules form a strand of molecules along the b-axis direction
Beitrag zur Eigenschaftsoptimierung von ausscheidungshärtbaren niedriglegierten Kupfer-Titan-Legierungen
Get PDFDie Arbeit befasst sich mit der Ausscheidungshärtung und deren Einfluss auf mechanische und elektrische Eigenschaften von Kupfer-Titan-Legierungen mit Legierungsgehalten unter 1 Ma.-% Titan. Ein besonderer Fokus lag dabei auf der Optimierung der erzielbaren elektrischen Leitfähigkeit bei gleichzeitig hoher Festigkeit. Die zentralen Inhalte der Untersuchungen waren:
• Der Einfluss des Titangehalts, der Temperatur und Dauer der Wärmebehandlung auf die aus der Ausscheidungshärtung resultierenden mechanischen und elektrischen Eigenschaftsänderungen wurde anhand von Legierungen mit 0,2 Ma.-% bis 1 Ma.-% Titan untersucht.
• Der Einfluss einer erhöhten Versetzungsdichte auf die Ausscheidungshärtung und die daraus resultierenden Eigenschaften wurde anhand von unterschiedlich stark kaltumgeformten und ausscheidungsgehärteten Proben ermittelt.
• Die Untersuchung des Optimierungspotentials der elektrischen Leitfähigkeit durch den Einsatz von geringen Mengen von Aluminium, Nickel, Silizium, Zink und Zinn.
• Die Bestimmung des Einflusses einer Kombination von vorgelagerter Kaltumformung und Einsatz eines dritten Legierungselements auf die aus der Ausscheidungshärtung resultierenden mechanischen und elektrischen Eigenschaften.
In der vorliegenden Arbeit wurde erstmals nach dem derzeit bekannten Stand der Technik und der Literatur umfassend die Ausscheidungshärtung von Kupfer-Titan-Legierungen mit weniger als 1 Ma.-% Titan untersucht. Bisherige Untersuchungen beschäftigten sich mit dem Bereich von 1,5 Ma.-% bis 6 Ma.-% Titan und in der industriellen Anwendung kommt bisher nur eine Legierung mit 3 Ma.-% Titan zum Einsatz. Aufgrund der guten, durch Ausscheidungshärtung erreichbaren, mechanischen Eigenschaften werden Kupfer-Titan-Legierungen in binärer Form oder als Mehrstofflegierungen mit Titan als Hauptlegierungselement als Substitutionswerkstoffe für Kupfer-Beryllium-Legierungen angesehen. So kommen diese vermehrt bei Steckverbindern im Automobilbau oder als Werkstoff für den Batteriekontakt oder die Kamera in Smartphones zum Einsatz. Jedoch weisen Kupfer-Titan-Legierungen eine deutlich geringere elektrischen Leitfähigkeit als Kupfer-Beryllium-Legierungen auf. Der Ansatz für die im Rahmen dieser Arbeit durchgeführten Untersuchungen ist, dass durch den Einsatz geringerer Titan-Gehalte in Kombination mit geeigneter Wärmebehandlung und Optimierung durch vorgelagerte Kaltumformung und den Einsatz weiterer Legierungselemente eine möglichst hohe elektrische Leitfähigkeit bei Erhalt guter mechanischer Eigenschaften erreichbar wird.
Die experimentellen Untersuchungen von Kupfer-Titan-Legierungen mit bis zu 1 Ma.-% Titan und deren Wärmebehandlungen zur Erzielung verschiedener Auslagerungszustände zeigen, dass vor allem Legierungen mit 0,8 Ma.-% bis 1 Ma.-% Titan ein großes Potential hinsichtlich einer Ausscheidungshärtung aufweisen. Bei diesen lassen sich durch die Ausscheidungshärtung gute mechanische Eigenschaften und eine gute elektrische Leitfähigkeit einstellen. Eine deutliche Steigerung dieser Werkstoffkennwerte ist vor allem durch eine vorgelagerte Kaltumformung zu erzielen. Die Verwendung geringer Anteile an Silizium und Zink führten zu einer Beschleunigung der Ausscheidungshärtung bei einem ähnlichen Eigenschaftsprofil. Durch den Einsatz einer vorgelagerten Kaltumformung bei den Legierungen mit geringen Zusätzen von dritten Elementen zeigte sich noch eine erheblich schnellere Aushärtung bei Erzielung guter Ergebnisse für die Härte, Zugfestigkeit und elektrische Leitfähigkeit. Vor allem die schnelle Aushärtung liefert eine gute Grundlage für eine wirtschaftliche und energieeffiziente Herstellung dieser Legierungen in einer industriellen Anwendung
Unconventional reservoir characterization using real samples based on differential thermal analysis, evaluation of rock parameters, and HC extraction using HP-CO2 aiming reservoir recovery recommendations
Get PDFTo meet the global hydrocarbon energy demand, it is imperative either to enhance the production from existing fields by applying innovative engineering solutions or discovering new field /resource areas. Both of these options are investigated by petroleum engineers intensively to tackle the challenges of meeting the ever-increasing demand. Meeting the energy demand as, like any other developing country, Jordan is facing a formidable challenge and requires exploration for conventional and unconventional hydrocarbon resources. As Jordan has a long exploration history for conventional reservoirs, Unconventional resource exploration and production seems to be the way to find new energy sources. Different exploration wells were drilled to evaluate the hydrocarbon potential. This research work is focusing on an experimental investigation to evaluate Jordanian hydrocarbon potential as well as to provide recommendations for future exploration activities in shale resources. The Evaluations were performed through comprehensive laboratory experiments that include measurements of Total Organic Content, Grain density, Pore Size Distribution, Specific Surface Area (BET), Mineralogy, Thermogravimetry Analysis, and Rock-Eval pyrolysis.
The petrophysical properties (TOC, grain density, pore size distribution) of Jordanian shale (nine different wells) are investigated. The TOC and grain density are in an inversely proportional relationship. The TOC results show a gradual increment with the depth. All the samples have higher porosity dominated by macro pores. Fourteen (14) samples were selected primarily based on TOC (above 1.5%) for further analysis. The specific surface area results show a proportional relationship with the TOC content. Considering the petrophysical properties and mineralogy, these Jordanian shales broadly can be considered as high porosity clay and mudstone type of shale.
Thermogravimetry analysis (TG/DTG) results indicate quantitative information related to organic and inorganic matter. Detection of thermos-reactive minerals, especially clay, carbonate, muscovite, pyrite is possible due to the combination of TG/DTG/DSC. The samples are examined under three different procedures which includes different heating programs. The oxidizing and inert atmospheric conditions (procedure i & ii) have the same heating program whereas procedure iii (inert atmospheric condition) has a heating program similar to the Rock-Eval pyrolysis program. The results of these samples show the complex nature of shale as well as organic matter by reacting in different stages (two or, three stages). Depending of the maturity of organic matter, the reaction occurring temperature range varies. Maximum oxidization reaction peaks happen between 479°C to 502°C. The maximum pyrolysis reaction peaks between 498°C to 521°C. Compared with complex heating (procedure iii) and rock Eval pyrolysis, S2 results indicate a high amount of inorganic compounds. Considering TGA reaction peaks and rock Eval pyrolysis results, these Jordanian shales indicate immature with low hydrocarbon generation potential.
The Jordanian shale samples are analyzed by using Rock-Eval pyrolysis. Analysis results are used to interpret petroleum potential in rocks. The most important information includes organic matter types (also connected with the depositional settings), organic matter thermal maturity, and the remaining hydrocarbon generation potential in the current form. The organic geochemical analysis results indicate mostly poor to no source rock potential except JF2-760 samples. The hydrogen index (HI) and oxygen index (OI) result suggests that type iii kerogen and type iii/ iv kerogen are most likely from terrestrial and varied settings origin. The low hydrogen, as well as, low S2 value indicate very little hydrocarbon generation potential. Similarly, The Tmax and PI data indicate immature to early mature source rock status and low conversion scenario.
Furthermore, the supercritical CO2 is injected into the samples, which is similar to gas flooding experiments to understand the recovery process. Hydrocarbon recovery or, CO2-shale interaction is determined by comparing three different properties (TOC, SSA, and TGA) pre-and-post supercritical CO2 injection. Supercritical CO2 injection in immature shale shows very limited property changes (TOC, SSA, and TGA) to the samples. However, in presence of hydrocarbon the pre-and post-injection property changes TOC, TGA, and SSA (BET) are noticeable enough to conclude HC recovery. Although in the case of immature shale with no hydrocarbon potential the kerogen or bitumen extraction has not been detected, which can be significant in the case of greenhouse gas storage, especially CCUS. This could reduce the risk of Organic Matter (OM) migration possibility in case immature shale formation is present in a suitable geological location
Improving drill-core hyperspectral mineral mapping using machine learning
Get PDFConsidering the ever-growing global demand for raw materials and the complexity of the geological deposits that are still to be found, high-quality extensive mineralogical information is required. Mineral exploration remains a risk-prone process, with empirical approaches prevailing over data-driven strategy. Amongst the many ways to innovate, hyperspectral imaging sensors for drill-core mineral mapping are one of the disruptive technologies. This potential could be multiplied by implementing machine learning. This dissertation introduces a workflow that allows the use of supervised learning to map minerals by means of ancillary data commonly acquired during exploration campaigns (i.e., mineralogy, geochemistry and core photography). The fusion of hyperspectral with such ancillary data allows not only to upscale to complete boreholes information acquired locally, but also to enhance the spatial resolution of the mineral maps. Thus, the proposed approaches provide digitally archived objective maps that serve as vectors for exploration and support geologists in their decision making.:List of Figures xviii
List of Tables xix
List of Acronyms xxi
1 Introduction 1
1.1 Mineral resources and the need for innovation . . . . . . . . . . . . . 2
1.2 Spectroscopy and hyperspectral imaging . . . . . . . . . . . . . . . . 5
1.2.1 Imaging spectroscopy ....................... 6
1.2.2 Spectroscopy of minerals ..................... 8
1.2.3 Mineral mapping.......................... 12
1.2.4 Mineral mapping in exploration ................. 15
1.2.5 Drill-core mineral mapping.................... 16
1.3 Machine learning .............................. 19
1.3.1 Supervised learning for drill-core hyperspectral data . . . . . 20
1.4 Motivation and approach ......................... 22
2 Hyperspectral mineral mapping using supervised learning and mineralogical data 25
Preface ....................................... 25
Abstract....................................... 26
2.1 Introduction ................................. 27
2.2 Data acquisition............................... 30
2.2.1 Hyperspectral data......................... 30
2.2.2 High-resolution mineralogica ldata . . . . . . . . . . . . . . . 31
2.3 Proposed system architecture ....................... 33
2.3.1 Re-sampling and co-registration ................. 33
2.3.2 Classification ............................ 35
2.4 Experimental results ............................ 36
2.4.1 Data description .......................... 36
2.4.2 Experimental setup......................... 37
2.4.3 Quantitative and qualitative assessment . . . . . . . . . . . . . 37
2.5 Discussion.................................. 40
2.6 Conclusion.................................. 42
3 Geochemical and hyperspectral data integration 45
Preface ....................................... 45
Abstract....................................... 46
3.1 Introduction ................................. 47
3.2 Basis for the integration of geochemical and hyperspectral data . . . 50
3.3 Proposed approach ............................. 51
3.3.1 Geochemical data labeling..................... 51
3.3.2 Superpixel segmentation ..................... 53
3.3.3 Classification ............................ 53
3.4 Experimental results ............................ 54
3.4.1 Data description .......................... 54
3.4.2 Data acquisition........................... 55
3.4.3 Experimental setup......................... 55
3.4.4 Assessment of the geochemical data labeling . . . . . . . . . . 58
3.4.5 Quantitative and Qualitative Assessment . . . . . . . . . . . . 58
3.5 Discussion.................................. 61
3.6 Conclusion.................................. 63
4 Improved spatial resolution for mineral mapping 65
Preface ....................................... 65
Abstract....................................... 66
4.1 Introduction ................................. 67
4.2 Methods: Resolution Enhancement for Mineral Mapping . . . . . . . 69
4.2.1 Hyperspectral Resolution Enhancement . . . . . . . . . . . . . 69
4.2.2 Mineral Mapping.......................... 71
4.2.3 Supervised Classification ..................... 71
4.3 Case Study.................................. 72
4.3.1 Data Acquisition .......................... 72
4.3.2 Resolution Enhancement Application . . . . . . . . . . . . . . 74
4.3.3 Evaluation of the Resolution Enhancement . . . . . . . . . . . 75
4.4 Results .................................... 76
4.4.1 Mineral Mapping.......................... 76
4.4.2 Supervised Classification ..................... 77
4.4.3 Validation .............................. 80
4.5 Discussion.................................. 82
4.6 Conclusions ................................. 84
5 Bibliography 9
Structureless Camera Motion Estimation of Unordered Omnidirectional Images
Get PDFThis work aims at providing a novel camera motion estimation pipeline from large collections of unordered omnidirectional images. In oder to keep the pipeline as general and flexible as possible, cameras are modelled as unit spheres, allowing to incorporate any central camera type. For each camera an unprojection lookup is generated from intrinsics, which is called P2S-map (Pixel-to-Sphere-map), mapping pixels to their corresponding positions on the unit sphere. Consequently the camera geometry becomes independent of the underlying projection model. The pipeline also generates P2S-maps from world map projections with less distortion effects as they are known from cartography. Using P2S-maps from camera calibration and world map projection allows to convert omnidirectional camera images to an appropriate world map projection in oder to apply standard feature extraction and matching algorithms for data association. The proposed estimation pipeline combines the flexibility of SfM (Structure from Motion) - which handles unordered image collections - with the efficiency of PGO (Pose Graph Optimization), which is used as back-end in graph-based Visual SLAM (Simultaneous Localization and Mapping) approaches to optimize camera poses from large image sequences. SfM uses BA (Bundle Adjustment) to jointly optimize camera poses (motion) and 3d feature locations (structure), which becomes computationally expensive for large-scale scenarios. On the contrary PGO solves for camera poses (motion) from measured transformations between cameras, maintaining optimization managable. The proposed estimation algorithm combines both worlds. It obtains up-to-scale transformations between image pairs using two-view constraints, which are jointly scaled using trifocal constraints. A pose graph is generated from scaled two-view transformations and solved by PGO to obtain camera motion efficiently even for large image collections. Obtained results can be used as input data to provide initial pose estimates for further 3d reconstruction purposes e.g. to build a sparse structure from feature correspondences in an SfM or SLAM framework with further refinement via BA.
The pipeline also incorporates fixed extrinsic constraints from multi-camera setups as well as depth information provided by RGBD sensors. The entire camera motion estimation pipeline does not need to generate a sparse 3d structure of the captured environment and thus is called SCME (Structureless Camera Motion Estimation).:1 Introduction
1.1 Motivation
1.1.1 Increasing Interest of Image-Based 3D Reconstruction
1.1.2 Underground Environments as Challenging Scenario
1.1.3 Improved Mobile Camera Systems for Full Omnidirectional Imaging
1.2 Issues
1.2.1 Directional versus Omnidirectional Image Acquisition
1.2.2 Structure from Motion versus Visual Simultaneous Localization and Mapping
1.3 Contribution
1.4 Structure of this Work
2 Related Work
2.1 Visual Simultaneous Localization and Mapping
2.1.1 Visual Odometry
2.1.2 Pose Graph Optimization
2.2 Structure from Motion
2.2.1 Bundle Adjustment
2.2.2 Structureless Bundle Adjustment
2.3 Corresponding Issues
2.4 Proposed Reconstruction Pipeline
3 Cameras and Pixel-to-Sphere Mappings with P2S-Maps
3.1 Types
3.2 Models
3.2.1 Unified Camera Model
3.2.2 Polynomal Camera Model
3.2.3 Spherical Camera Model
3.3 P2S-Maps - Mapping onto Unit Sphere via Lookup Table
3.3.1 Lookup Table as Color Image
3.3.2 Lookup Interpolation
3.3.3 Depth Data Conversion
4 Calibration
4.1 Overview of Proposed Calibration Pipeline
4.2 Target Detection
4.3 Intrinsic Calibration
4.3.1 Selected Examples
4.4 Extrinsic Calibration
4.4.1 3D-2D Pose Estimation
4.4.2 2D-2D Pose Estimation
4.4.3 Pose Optimization
4.4.4 Uncertainty Estimation
4.4.5 PoseGraph Representation
4.4.6 Bundle Adjustment
4.4.7 Selected Examples
5 Full Omnidirectional Image Projections
5.1 Panoramic Image Stitching
5.2 World Map Projections
5.3 World Map Projection Generator for P2S-Maps
5.4 Conversion between Projections based on P2S-Maps
5.4.1 Proposed Workflow
5.4.2 Data Storage Format
5.4.3 Real World Example
6 Relations between Two Camera Spheres
6.1 Forward and Backward Projection
6.2 Triangulation
6.2.1 Linear Least Squares Method
6.2.2 Alternative Midpoint Method
6.3 Epipolar Geometry
6.4 Transformation Recovery from Essential Matrix
6.4.1 Cheirality
6.4.2 Standard Procedure
6.4.3 Simplified Procedure
6.4.4 Improved Procedure
6.5 Two-View Estimation
6.5.1 Evaluation Strategy
6.5.2 Error Metric
6.5.3 Evaluation of Estimation Algorithms
6.5.4 Concluding Remarks
6.6 Two-View Optimization
6.6.1 Epipolar-Based Error Distances
6.6.2 Projection-Based Error Distances
6.6.3 Comparison between Error Distances
6.7 Two-View Translation Scaling
6.7.1 Linear Least Squares Estimation
6.7.2 Non-Linear Least Squares Optimization
6.7.3 Comparison between Initial and Optimized Scaling Factor
6.8 Homography to Identify Degeneracies
6.8.1 Homography for Spherical Cameras
6.8.2 Homography Estimation
6.8.3 Homography Optimization
6.8.4 Homography and Pure Rotation
6.8.5 Homography in Epipolar Geometry
7 Relations between Three Camera Spheres
7.1 Three View Geometry
7.2 Crossing Epipolar Planes Geometry
7.3 Trifocal Geometry
7.4 Relation between Trifocal, Three-View and Crossing Epipolar Planes
7.5 Translation Ratio between Up-To-Scale Two-View Transformations
7.5.1 Structureless Determination Approaches
7.5.2 Structure-Based Determination Approaches
7.5.3 Comparison between Proposed Approaches
8 Pose Graphs
8.1 Optimization Principle
8.2 Solvers
8.2.1 Additional Graph Solvers
8.2.2 False Loop Closure Detection
8.3 Pose Graph Generation
8.3.1 Generation of Synthetic Pose Graph Data
8.3.2 Optimization of Synthetic Pose Graph Data
9 Structureless Camera Motion Estimation
9.1 SCME Pipeline
9.2 Determination of Two-View Translation Scale Factors
9.3 Integration of Depth Data
9.4 Integration of Extrinsic Camera Constraints
10 Camera Motion Estimation Results
10.1 Directional Camera Images
10.2 Omnidirectional Camera Images
11 Conclusion
11.1 Summary
11.2 Outlook and Future Work
Appendices
A.1 Additional Extrinsic Calibration Results
A.2 Linear Least Squares Scaling
A.3 Proof Rank Deficiency
A.4 Alternative Derivation Midpoint Method
A.5 Simplification of Depth Calculation
A.6 Relation between Epipolar and Circumferential Constraint
A.7 Covariance Estimation
A.8 Uncertainty Estimation from Epipolar Geometry
A.9 Two-View Scaling Factor Estimation: Uncertainty Estimation
A.10 Two-View Scaling Factor Optimization: Uncertainty Estimation
A.11 Depth from Adjoining Two-View Geometries
A.12 Alternative Three-View Derivation
A.12.1 Second Derivation Approach
A.12.2 Third Derivation Approach
A.13 Relation between Trifocal Geometry and Alternative Midpoint Method
A.14 Additional Pose Graph Generation Examples
A.15 Pose Graph Solver Settings
A.16 Additional Pose Graph Optimization Examples
Bibliograph
Investigation of alternative supplementary cementitious materials and a new method to produce them
Get PDFZementklinker ist der Hauptbestandteil von Zement und verbraucht zu dessen Herstellung signifikante Mengen von natürlichen Ressourcen und trägt gleichzeitig zu seiner sehr ungünstigen Treibhausgasbilanz bei. In dieser Arbeit wird gezeigt, dass Zementersatzstoffe mit spezifischen Eigenschaften aus Abfallstoffen wie Kieswaschschlämmen, Strassenwaschschlämmen und Gipskartonplatten ohne Leistungseinbußen auf Produktseite, bei geringeren Temperaturen und geringerer CO2 Emission hergestellt werden können. Entsprechend den angestrebten Eigenschaften solcher zum Teil anthropogener Zementbestandteile wurden lokal verfügbare geeignete Abfallstoffe ausgewählt und thermisch aktiviert. Eine industriell anwendbare Methode zur Aktivierung solcher Stoffe bei Temperaturen von 700 °C – 850 °C wurde entwickelt und patentiert. Es basiert auf einem neu entwickelten Trocknungsverfahren und der Kombination von zwei Produktionslinien, um durch die Verknüpfung der Gasströme beider Systeme eine energieeffiziente thermische Behandlung von Abfallstoffen zu ermöglichen sowie auf umweltfreundliche Weise einen Zementersatzstoff herzustellen.:Table of Contents
List of Tables
List of Figures
List of Abbreviations
Glossary
Chapter 1: Introduction
1.1 Motivation
1.2 Research hypotheses and objectives
1.3 Research methodology
1.4 Thesis outline
Chapter 2: State of the art in SCM production
2.1 Supplementary cementitious materials
2.2 Classification of SCMs
2.2.1 Classification according to origin
2.2.2 Classification according to reaction behaviour
2.3 Chemical composition of SCMs
2.4 Formation of hydraulic or pozzolanic minerals in thermal processes
2.4.1 Cement clinker
2.4.2 Burnt oil shale
2.4.3 Fly ash
2.4.4 Calcined clay
2.5 Performance of composite cements
2.6 Calcining technologies
2.6.1 Flash calciner
2.6.2 Rotary calciner
2.7 Comparison of process technologies
2.8 Summary of Chapter 2
Chapter 3: Alternative SCMs and a new method for activation
3.1 Introduction
3.2 Target of alternative SCM
3.3 Waste materials
3.3.1 Aggregate washing sludge
3.3.2 Road cleaning sludge
3.3.3 Deconstruction gypsum
3.4 Producing alternative SCMs
3.5 Thermal activation of alternative SCMs
3.6 Limitations in current calcining technology
3.6.1 Difficult emission control
3.6.1.1 Particulate emission
3.6.1.2 Gaseous emission
3.6.2 Challenging material preparation
3.6.3 Demand for noble fuels
3.6.4 Difficult colour control
3.6.5 Strict temperature control
3.6.6 CO2 footprint of calciners
3.7 Proposed new method of calcination
3.7.1 Feed material handling
3.7.2 Thermal heat-exchange system
3.7.3 Clay calciner design
3.7.4 Grinding
3.8 Summary Chapter 3
Chapter 4: Theoretical Considerations
4.1 Material considerations
4.1.1 Composition of alternative SCM
4.1.2 Anticipated products and characteristics
4.2 Process considerations
4.2.1 System capacity
4.2.2 Material characteristics
4.2.3 Material receiving, crushing and handling
4.2.4 Thermodynamic modelling
4.2.4.1 Mass balance
4.2.4.2 Drying and cooling heat balance
4.2.4.3 Calcination heat balance
4.2.4.4 Gas balance
4.2.4.5 Impact on clinker kiln line
4.2.4.6 Impact of calcite on the gas balance
4.2.5 Calciner design
4.2.6 Colour control
4.2.7 Emission prediction
4.2.7.1 Emission during drying
4.2.7.2 Emission during calcination
4.2.8 CO2 footprint of produced material
4.2.9 Grinding requirements
4.3 Summary of Chapter 4
Chapter 5: Experimental tests and proof of concept
5.1 Introduction
5.2 Sampling and characterization
5.2.1 Kaolinitic AWS from France
5.2.2 Non-kaolinitic AWS from Switzerland
5.2.3 Road cleaning sludges from Switzerland
5.2.4 Deconstruction gypsum from Switzerland
5.2.5 Sample preparation and shipping
5.3 Drying screw conveyor testing
5.4 Calcination testing
5.4.1 Mineralogy of activated products
5.4.1.1 Non-kaolinitic SCM
5.4.1.2 Kaolinitic AWS from France
5.4.2 Colour
5.5 Crushing tests
5.6 Grinding tests
5.7 Mortar compressive strength testing
5.8 Water demand testing
5.9 Summary of Chapter 5
Chapter 6: Experimental results
6.1 Characteristics of activated materials
6.2 Concrete performance and colour
6.2.1 Thermally activated kaolinitic AWS from France
6.2.2 Thermally activated non-kaolinitic alternative SCM from Switzerland
6.3 Equipment dimensioning
6.3.1 Process mass flow
6.3.2 Heat-exchanging screws and thermal oil system
6.3.3 Rotary calciner dimensioning
6.3.4 Ball mill dimensioning
6.4 CO2 reduction
6.5 Summary of Chapter 6
Chapter 7: Conclusion and outlook
7.1 Conclusions
7.2 Outlook.
Literatur
Universal electromagnetic response relations: applied to the free homogeneous electron gas
Get PDFDie vorliegende Arbeit befasst sich mit der Anwendung des kürzlich entwickelten 'Functional Approach' zur Elektrodynamik in Medien auf das Modell des freien homogenen Elektronengases. Basierend auf einer ausschließlich mikroskopischen Feldtheorie wird gezeigt, dass mittels universell gültiger Relationen zwischen Antwortfunktionen sowohl alle relevanten optischen als auch magnetischen (linearen) Materialeigenschaften allein aus der Strom-Strom-Korrelation gewonnen werden können. Dabei ist es essentiell, alle Berechnungen auf dem vollen Stromdichteoperator aufzubauen, also auf der Summe aus diamagnetischem, orbitalem und spinoriellem Anteil. Weiterhin wird anhand der magnetischen Suszeptibilität demonstriert, dass im Allgemeinen die Unterscheidung zwischen eigenen und direkten Antwortfunktionen nicht zu vernachlässigen ist. Schließlich wird mit dem „Lindhard-Integral-Theorem“ bewiesen, dass nicht nur der longitudinale, sondern auch der transversale Anteil des vollen frequenz- und wellenvektorabhängigen fundamentalen Antworttensors des freien Elektronengases komplett durch das charakteristische Lindhard-Integral bestimmt ist.:Introduction
I Microscopic electrodynamics in media
1 Classical electrodynamics
1.1 Covariant formulation
1.2 Temporal gauge
1.3 Free Green function
1.4 Total functional derivatives
2 Electrodynamics in media
2.1 Field identifications
2.2 Fundamental response tensor
2.3 Universal response relations
2.4 Direct and proper response
2.5 Isotropic and combined limits
2.6 Full Green function
2.7 Wave equations in media and dispersion relations
II Application to the free electron gas
3 Fundamental response tensor
3.1 Electromagnetic current density
3.2 Kubo-Greenwood formulae
3.3 Diamagnetic, orbital and spinorial contribution
3.4 Spin susceptibility vs. spinorial current response
4 London model and diamagnetic response
4.1 Interpretation as response function
4.2 Application of universal response relations
4.3 Spin correction
5 Full current response
5.1 Dimensionless formulae
5.2 Lindhard integral theorem
5.3 Laurent expansions
5.4 Optical properties
5.5 Magnetic properties
Conclusion
Appendix A - Notation
Appendix B - Formulary
B.1 Basic analysis and vector calculus
B.2 Special relativity theory
B.3 Fourier transformation
B.4 Functional derivatives
B.5 Projectors and Helmholtz' theorem
B.6 Complex analysis
Appendix C - Yang-Mills gauge theory
C.1 Field strength tensor
C.2 Minimal coupling principle
C.3 Gauge invariant quantities and equations
Appendix D - Periodic solids
D.1 Partitioning of reciprocal space
D.2 Homogeneous limit
Appendix E - Electromagnetic spectrum
Bibliography
Acknowledgements
ErrataThis thesis is concerned with the application of the recently developed 'Functional Approach' to electrodynamics of media to the model of the free homogeneous electron gas. Based on an exclusively microscopic field theory it is shown that with the help of universally valid relations between response functions, all relevant optical and magnetic (linear) materials properties can be extracted from the mere current-current response. For this purpose, it is essential to base all calculations on the full current density operator, i.e. the sum of diamagnetic, orbital and spinorial contributions. Furthermore, we use the example of the magnetic susceptibility to demonstrate that the distinction between proper and direct response functions is in general crucial. Lastly, with the “Lindhard integral theorem” we prove that not only the longitudinal but also the transverse part of the full frequency- and wavevector-dependent fundamental response tensor of the free electron gas is completely determined by the characteristic Lindhard integral.:Introduction
I Microscopic electrodynamics in media
1 Classical electrodynamics
1.1 Covariant formulation
1.2 Temporal gauge
1.3 Free Green function
1.4 Total functional derivatives
2 Electrodynamics in media
2.1 Field identifications
2.2 Fundamental response tensor
2.3 Universal response relations
2.4 Direct and proper response
2.5 Isotropic and combined limits
2.6 Full Green function
2.7 Wave equations in media and dispersion relations
II Application to the free electron gas
3 Fundamental response tensor
3.1 Electromagnetic current density
3.2 Kubo-Greenwood formulae
3.3 Diamagnetic, orbital and spinorial contribution
3.4 Spin susceptibility vs. spinorial current response
4 London model and diamagnetic response
4.1 Interpretation as response function
4.2 Application of universal response relations
4.3 Spin correction
5 Full current response
5.1 Dimensionless formulae
5.2 Lindhard integral theorem
5.3 Laurent expansions
5.4 Optical properties
5.5 Magnetic properties
Conclusion
Appendix A - Notation
Appendix B - Formulary
B.1 Basic analysis and vector calculus
B.2 Special relativity theory
B.3 Fourier transformation
B.4 Functional derivatives
B.5 Projectors and Helmholtz' theorem
B.6 Complex analysis
Appendix C - Yang-Mills gauge theory
C.1 Field strength tensor
C.2 Minimal coupling principle
C.3 Gauge invariant quantities and equations
Appendix D - Periodic solids
D.1 Partitioning of reciprocal space
D.2 Homogeneous limit
Appendix E - Electromagnetic spectrum
Bibliography
Acknowledgements
Errat
Evolution of particle morphology during char conversion processes applied for the CFD modeling of an entrained-flow gasifier
Get PDFThe change in morphology of a char particle affects both its trajectory and carbon consumption rate, hence the performance and efficiency of an entrained-flow gasifier. Among key processes taking place in the gasifier, the char conversion process is a limiting step for the overall carbon conversion. For that reason, the Ph.D. thesis presents the evolution of morphology of char particles during the carbon conversion process using particle-resolved transient CFD calculations. Analyses of numerical data obtained from the transient CFD calculations were carried out. As a result, new sub models related to the drag coefficient and the fundamental parameters of char conversion model were emerged. The new sub models were applied for modeling a pressured entrained-flow gasifier at laboratory scale. The numerical results of the gasifier show a good agreement with experimental data and an improvement of the sub models applied
Multivariate Untersuchungen in Gasphasenprozessen und Aerosolen mittels Raman-Spektroskopie
Get PDFFür Entwurf, Modellierung sowie Überwachung von Gasphasenprozessen sind fun-dierte Kenntnisse über elementare Zustandsgrößen wie Temperatur oder Spezieskon-zentration unerlässlich. Obwohl bereits heute eine breite Palette an optischen, nicht-invasiven Online-Messtechniken zu Verfügung steht, ist deren Einsatz noch immer auf wenige Anwendungsfelder beschränkt. Die Gründe dafür liegen im oft hohen ex-perimentellen Aufwand oder in anderen Nachteilen wie der Notwendigkeit zum Einsatz von Tracern oder der Kalibrierung über zusätzliche Referenzen.
Um diese Nachteile zu umgehen, wurde im Rahmen dieser Arbeit ein mobiles, faserbasiertes Sensorsystem, basierend auf der spontanen Raman-Spektroskopie entwickelt. Die Technik verwendet durchstimmbare NIR-Dauerstrich-Laser-Anregung, Signalerfassung in rückstreuender Geometrie (Punktmessung) und erfordert weder Probennahme, noch Tracer innerhalb der Strömung oder Kalibrierschritte am zu untersuchenden Prozess. Die Methode ermöglicht die simultane Bestimmung von Gastemperaturen und Spezieskonzentrationen sowie im Falle von Aerosolen die Bestimmung der Partikelspezies und der Anteile ihrer polymorphen Kristallstrukturen.
Die Datenauswertung basiert auf der Rekonstruktion der gemessenen Spektren anhand simulierter Modellspektren durch Least-Square-Algorithmen. Herkömmliche Ansätze liefern lediglich Parameter, die das Residuum zwischen Simulation und Messsignal minimieren. Unsicherheiten der Messgrößen sind daraus nicht ermittelbar und werden deshalb konventionell durch Wiederholung der Messung bestimmt. Mit Hilfe der hier eingesetzten Bayes'schen Statistik lassen sich die entsprechenden Unsicherheiten direkt bestimmen. Darüber hinaus ermöglicht der Ansatz das Einbeziehen von Vorwissen zur Verbesserung der Robustheit und Genauigkeit der Auswertung.
Die Performance des Sensorsystems wurde durch Einsätze an verschiedenen Gasphasenprozessen getestet und evaluiert. Dazu gehören Test-Aerosole, ein TiO2-Nanopartikelsyntheseprozess sowie eine laminare, rußarme Flamme. Ein leicht modifiziertes Sensorsystem (VIS-Anregung) wurde an einem Vergasungsreaktor eingesetzt.
Generell konnte eine hohe Qualität der ermittelten Messgrößen festgestellt werden. So sind deren Unsicherheiten mit denen deutlich komplexerer Messtechniken vergleichbar, stellenweise sogar geringer. Die mittlere Unsicherheit der Gastemperaturen innerhalb der Flamme betrug nur 1,6 %. Somit ermöglicht der vorgestellte Sensor bei geringem experimentellen Aufwand die Bestimmung wertvoller Prozessdaten und stellt so potentiell die Basis für eine breitere Anwendung optischer Prozessmesstechnik dar.For the design, modelling and monitoring of gas-phase processes a profound knowledge of elementary state variables such as temperature or species concentration is essential. Although a wide range of optical, non-invasive online measurement techniques is already available today, their use is still limited to a few fields of application. The reasons for this are the regularly high experimental effort or other disadvantages such as the necessity to use tracers or to execute calibration via additional references.
In order to avoid these disadvantages, a mobile, fiber-based sensor system based on spontaneous Raman spectroscopy was developed within the scope of this work. The technique uses tunable NIR continuous-wave laser excitation, signal acquisition in backscattering geometry (point measurement) and requires neither sampling, tracers within the flow nor calibration steps at the process under investigation. The method allows the simultaneous determination of gas temperatures and species concentrations and, in the case of aerosols, the determination of the particle species and their polymorphic crystal structures.
The data evaluation is based on the reconstruction of the measured spectra using simulated model spectra through least square algorithms. Conventional approaches only provide parameters that minimize the residual between simulation and measurement signal. Uncertainties of the measured variables cannot be determined from these parameters and are, therefore, determined conventionally by repeating the measurement. With the help of the Bayesian statistics used here, the corresponding uncertainties can be determined directly. Furthermore, the approach allows the inclusion of prior knowledge to improve the robustness and accuracy of the evaluation.
The performance of the sensor system was tested and evaluated by using it in different gas phase processes. These include test aerosols, a TiO2 nanoparticle synthesis process and a laminar weakly sooting flame. A slightly modified system (VIS excitation) was used with a similar operation strategy at a gasification reactor.
In general, a high quality of the measured variables could be determined. Their uncertainties are comparable with those of much more complex measuring techniques, in some cases even lower. The mean uncertainty of the gas temperatures within the flame was only 1.6 %. Thus, the presented sensor enables the determination of valuable process data with low experimental effort and can potentially be the basis for a broader application of optical process measurement technology
Reibkontakteinflüsse zwischen Partikeln und Festkörpern auf die Schwingungsselbsterregung
Get PDFDer Reibkontakt zwischen zwei Körpern hat entscheidende Einflüsse auf die Schwingungsselbsterregung. Da in der Literatur bisher vorwiegend ein Festkörper-Festkörper-Kontakt im Fokus steht, beschäftigt sich diese Arbeit mit einem Partikel-Festkörper-Kontakt. Dabei stehen Partikelsysteme in Form von Schüttgütern im Mittelpunkt. Ein bekanntes Beispiel solcher selbsterregten Schwingungen sind Silovibrationen. Dies sind Stick-Slip-Schwingungen beim Entleerungsvorgang von dünnwandigen Metallsilos. Untersuchungen mittels Fouriertransformation zeigen, dass die hörbaren Schwingungen sich aus einer Grundharmonischen und mehreren Oberwellen zusammensetzen. Diese Frequenzen sind allerdings weit
oberhalb der numerisch untersuchten ersten Eigenfrequenzen der Silos.
Ein Schwerpunkt der Arbeit liegt in den experimentellen Untersuchungen der Stick-Slip-Frequenz eines Schüttgut-Wand-Systems in einem speziell dafür entwickelten Versuchsstand. Es werden sowohl Systemkenngrößen, wie z.B. Geschwindigkeit, Systemsteifigkeit oder Masse, als auch tribologische Kenngrößen, wie z.B. Kontaktfläche oder -pressung, Materialkombination und Wandbeschaffenheit, auf ihren Einfluss auf die Stick-Slip-Frequenz untersucht. Ergänzend dazu wird die reale Kontaktfläche im statischen Zustand und bei einer äußeren dynamischen Anregung zwischen den Randpartikeln und einem Festkörper untersucht. Des Weiteren wird der tatsächliche Reibwert über der Relativgeschwindigkeit in Form einer Reibhysterese gemessen.
In den Simulationsstudien wird ein Modell eines Reibschwingers vorgestellt und untersucht. Hier zeigen sich bereits bei einer stationären Kennlinie große Unterschiede in der Stick-Slip-Neigung und der Frequenz. In einer Modellerweiterung mittels einer zeitabhängigen Reibhysterese werden weiterführende Modellstudien getätigt. Hierbei steht vor allem das zeitabhängige Reibverhalten in der Haft- und Gleitphase im Fokus der Untersuchungen.The friction contact between two bodies has an important influence on self-excited vibrations. Often the main focus is on a solid-solid contact. Therefore, this thesis focuses on a particle-solid contact, represented as the interaction between a bulk solid and a wall. Silo vibrations are a well known example of this kind of self-excited vibrations. Stick-slip vibrations occure during the discharging of thin walled metal silo. The hearable vibrations consist of a basic harmonic and some higher harmonics. The frequencies can be detected by a Fourier transform.
One main focus of this thesis is the experimental investigation of the stick-slip frequency of a bulk solid-wall system. Therefore, a special test rig is designed. The investigation concentrates on system parameters, e.g. velocity, system stiffness or mass, on tribological parameters, e.g. contact area, pressure, material combination and wall surfaces, and their influence on the stick-slip frequency. Additional, the real contact area between particles in wall proximity and the wall itself is investigated in a static situation and during an external dynamic excitation. Furthermore, the real friction coefficient over the relative velocity will be measured.
A model of a single mass friction oscillator will be presented and investigated in the simulation studies. Even with stationary friction characteristics this studies show big differences in the stick-slip stability and frequency. Henceforth, an advanced model with friction characteristics dependent on time in the form of a friction hysteresis is presented. There, the main focus is on the time dependent friction behaviour during the stick and slip phase of the oscillation