Technische Universität Bergakademie Freiberg: Qucosa
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Die Bibliothek der Bergakademie Freiberg in den Jahren 1945 bis 1990
Full text linkDargestellt wird die Geschichte der Bibliothek der Bergakademie Freiberg in den Jahren 1945 bis 1990
Was sind FAIRe Daten?
Full text linkDie sog. FAIR-Prinzipien haben sich mittlerweile als Standard-Anforderung im Forschungsdatenmanagement etabliert. In Förderanträgen und -berichten müssen Wissenschaftler:innen darlegen, wie sie Forschungsdaten gemäß den FAIR-Prinzipien verwalten und veröffentlichen. Auch immer mehr Fachzeitschriften bzw. Verlage fordern von ihren Autor:innen, dass sie ihre Forschungsdaten gemäß den FAIR-Prinzipien teilen, um die Reproduzierbarkeit und Überprüfbarkeit ihrer Ergebnisse zu gewährleisten. Was das Akronym FAIR eigentlich bedeutet und worauf Forschende in diesem Zusammenhang achten sollten, fasst dieser Beitrag kurz zusammen
Crystal structures of monohydrate and methanol solvate compounds of {1-[(3,5-bis{[(4,6-dimethylpyridin-2-yl)amino]methyl}-2,4,6-triethylbenzyl)amino]cyclopentyl}methanol
Full text linkIn the title monohydrate compound, 1a, and the methanol solvate compound, 1b, the triethylbenzene derivative, C35H51N5O, has three functionalized side arms and three ethyl groups, the former being located on one side of the central benzene ring, while the latter are directed to the opposite side. Both the crystals are constructed of structurally similar dimers of 1:1 host–guest complexes held together by N—H...O and O—H...N hydrogen bonds, and in 1a additionally by O—H...O hydrogen bonds. The structure of 1b contains additional highly disordered solvent molecules. Thus, the SQUEEZE routine [Spek (2015). Acta Cryst. C71, 9–18] in PLATON was used to generate a modified data set, in which the contribution of the disordered molecules to the structure amplitudes is eliminated. These solvent molecules are not considered in the reported chemical formula
Turbulent fluid flow in rough rock fractures
Full text linkThis thesis is dedicated to the study of the turbulent fluid flow in rough-walled rock fractures. Fracture models were generated from 3D scans of fractured rock samples, while fluid flow was simulated numerically by means of FVM-based open-source CFD toolbox OpenFOAM, employing the high-performance computing cluster for the more demanding 3D models.
First part of the thesis addresses the issue of fracture geometry. Realistic 2D and 3D fracture models were constructed from 3D scans of upper and lower halves of a fractured rock sample, taking both shear displacement and contact spots into account. Furthermore, we discuss the shortcomings of the available fracture aperture metrics and propose a new aperture metric based on the Hausdorff distance; imaging performance of the new metric is shown to be superior to the conventional vertical aperture, especially for rough fracture surfaces with abundant ridges and troughs.
In the second part of the thesis we focus on the fluid flow through the rock fracture for both 2D and 3D cases. While previous studies were largely limited to the fully viscous Darcy or inertial Forchheimer laminar flow regimes, we chose to investigate across the widest possible range of Reynolds numbers from 0.1 to 10^6, covering both laminar and turbulent regimes, which called for a thorough investigation of suitable turbulence modeling techniques. Due to narrow mean aperture and high aspect ratio of the typical fracture geometry, meshing posed a particularly challenging problem. Taking into account limited computational resources and a sheer number of model geometries, we developed a highly-optimised workflow, employing the steady-state RANS simulation approach to obtain time-averaged flow fields. Our findings show that while flow fields remain mostly stationary and undisturbed for simpler contactless geometries, emergence of contact spots immediately triggers a transition to non-stationary flow starting from Re ∼ 10^2, which is reflected by the streamline tortuosity data. This transition disrupts the flow pattern across the fracture plane, causing strong channeling and large separation bubbles, with area of the latter being much larger than the generating contact spots. Adverse influence of the contact spots on the overall permeability is strong enough to override any benefits of aperture increase during shear and dilation. Contactless 3D models can to a certain degree be approximated by their 2D counterparts. Lastly, we investigate the influence of both shearing and contact spots on the overall permeability and friction factor of the fracture, drawing a parallel to the well-studied area of turbulent flow in rough-walled pipes and ducts. Unlike the latter, 3D curvilinear fracture geometries exhibit a gapless laminar–turbulent transition, behaving as a hydraulically rough channel in the turbulent range as the shear displacement increases
Molecularly Imprinted Polymer-Based Sensors for Priority Pollutants
Full text linkGlobally, there is growing concern about the health risks of water and air pollution. The U.S. Environmental Protection Agency (EPA) has developed a list of priority pollutants containing 129 different chemical compounds. All of these chemicals are of significant interest due to their serious health and safety issues. Permanent exposure to some concentrations of these chemicals can cause severe and irrecoverable health effects, which can be easily prevented by their early identification. Molecularly imprinted polymers (MIPs) offer great potential for selective adsorption of chemicals from water and air samples. These selective artificial bio(mimetic) receptors are promising candidates for modification of sensors, especially disposable sensors, due to their low-cost, long-term stability, ease of engineering, simplicity of production and their applicability for a wide range of targets. Herein, innovative strategies used to develop MIP-based sensors for EPA priority pollutants will be reviewed
Crystal structures of 2-[3,5-bis(bromomethyl)-2,4,6-triethylbenzyl]isoindoline-1,3-dione and 2-{5-(bromomethyl)-3-[(1,3-dioxoisoindolin-2-yl)methyl]-2,4,6-triethylbenzyl}isoindoline-1,3-dione
Full text linkThe title compounds, C23H25Br2NO2 (1) and C31H29BrN2O4 (2), crystallize in the space group P21/n with two (1-A and 1-B) and one molecules, respectively, in the asymmetric unit of the cell. The molecular conformation of these compounds is stabilized by intramolecular C—H⋯O hydrogen bonds and C—H⋯N or C—H⋯π interactions. The crystal structure of 1 features a relatively strong Br⋯O=C halogen bond, which is not observed in the case of 2. Both crystal structures are characterized by the presence of C—H⋯Br hydrogen bonds and numerous intermolecular C—H⋯O hydrogen-bonding interactions
Efficient Finishing of Laser Beam Melting Additive Manufactured Parts
Full text linkIn many cases, the functional performance of additively manufactured components can only be ensured by finishing the functional surfaces. Various methods are available for this purpose. This paper presents a procedure for selecting suitable processes for finishing laser beam melting additive–manufactured parts which is ultimately based on technological knowledge. It was experimentally proven that the use of several consecutive finishing processes is beneficial to achieve better surface quality. One finishing process chain was particularly effective (namely particle blasting/vibratory grinding/plasma electrolytic polishing) and the technological limits of this method were investigated in this study. The optimal parameters for this process combination ensured a surface roughness Sa < 1 µm
Abraham Gottlob Werner und die Geowissenschaften seiner Zeit: zum 200. Todestag des Geologen, Mineralogen und Montanwissenschaftlers : ausgewählte Vorträge des Internationalen Werner-Symposiums vom 29. Juni bis 1. Juli 2017
Full text linkDie Universitätsbibliothek der TU Bergakademie Freiberg veranstaltete vom 29. Juni bis 1. Juli 2017 das Internationale Symposium 'Abraham Gottlob Werner (1749 - 1817) und die Geowissenschaften seiner Zeit - zum 200. Todestag des Geologen, Mineralogen und Montanwissenschaftlers'.
Themenschwerpunkte des Symposiums waren u.a. die geowissenschaftlichen Netzwerke des ausgehenden 18. und beginnenden 19. Jahrhunderts und deren Einfluss auf die Forschung und Lehre Abraham Gottlob Werners
Investigation of mining subsidence prediction under tectonic influences
Full text linkThis dissertation addresses the challenge of predicting human-induced subsidence in tectonic settings. The study focuses on the non-symmetric and shape-defying nature of subsidence troughs in tectonic regions, which deviates from conventional symmetric models. The aim of the dissertation is to improve the accuracy of subsidence prediction by incorporating horizontal stress effects into empirical methods. Through a combination of numerical investigations and empirical modelling, the research reveals stress-induced patterns in subsidence profiles. The developed model, based on various concepts, successfully incorporates asymmetry and shape deviation, resulting in significantly improved prediction accuracy. Application of the model to a real subsidence case in a salt cavern shows a 30% improvement in prediction (based on mean squared error comparison with classical solution). This new solution covers subsidence profile patterns not previously considered by empirical models.:Inhalt
1 Introduction
2 State of the art
2.1 Subsidence prediction methods
2.1.1 Empirical subsidence prediction method overview
2.1.2 Numerical methods for subsidence prediction
2.2 Subsidence monitoring methods
2.2.1 Observation methods
2.2.2 Interplay and evolution of techniques
2.3 Subsidence anomalies
2.4 In-situ-stress field
2.5 Subsidence prediction methods for anomalies
2.6 Conclusions
3 Goals and objectives
4 Foundations
4.1 Empirical subsidence prediction methods
4.1.1 Convergence
4.1.2 Transmission coefficient
4.1.2 Influence factor
4.2 Numerical models for subsidence case
4.2.1 Grid size for subsidence case
4.2.2 Boundary conditions
4.2.3 Constitutive models
4.3 Validation
4.3.1 Observation methods
4.3.2 Parameter estimation
4.3.3 Global parameter estimation
4.3.4 Local parameter estimation
4.3.5 Quality measures for result valuation and validation
5 Methodology
6 Numerical investigation
6.1 Preliminary investigation
6.1.1 Method
6.1.2 Choice of constitutive model
6.1.3 Model and input data
6.1.4 Preliminary investigation results
6.2 Design of the main experiment: non-uniform stress distribution
6.2.1 Constitutive model and input data
6.2.2 Model simplification
6.2.3 Output data
6.3 Contribution of asymmetrical stress distribution
6.3.1 Discussion of the basic distribution form
6.3.2 Discussion of maximum subsidence
6.3.3 Discussion of assymetry
6.3.4 Discussion of influence angle
6.4 Conclusions
7 Adaptation of an empirical model to the discovered features
7.1 Subsidence asymmetry
7.2 Subsidence shape flexibility
7.3 Unifying solution
7.4 Conclusion and outlook
8 Application to a full scale
8.1 General information for a salt cavern storage field
8.2 Estimation of the observed subsidence surface as reference
8.3 Model implementation
8.3.1 Parameter estimation results
8.4 Statistical validation of models
8.5 Conclusions
9 Conclusion
9.1 Limitations
9.2 Outlook
References
Appendi
Guidelines for publications at the TU Bergakademie Freiberg
Full text linkThe Technische Universität Bergakademie Freiberg (TUBAF) aims to make the research achievements of its academics visible and accessible and to ensure the usability of these achievements for the future research process. It endeavors to showcase the research achievements of the university, which are particularly evident in the form of publications and the frequency of their citations. This requires researchers to be clearly assigned to the publications they have contributed to and to their university (affiliation). Increased visibility of publications and transparent assessment of the associated research performance also facilitates appropriate quality assurance. This is of particular importance both for the researchers and for the university in national and international comparison as well as in the competition for research funding and cooperation partners