TY - CONF
AU - Sander, Tom
AU - Lange, Sven
AU - Hilleringmann, Ulrich
AU - Geneis, Volker
AU - Hedayat, Christian
AU - Kuhn, Harald
AU - Gockel, Franz-Barthold
ID - 39392
T2 - 2021 22nd IEEE International Conference on Industrial Technology (ICIT)
TI - Detection of Defects on Irregular Structured Surfaces by Image Processing Methods for Feature Extraction
ER -
TY - CONF
AU - Lange, Sven
AU - Schroder, Dominik
AU - Hedayat, Christian
AU - Kuhn, Harald
AU - Hilleringmann, Ulrich
ID - 39390
T2 - 2021 22nd IEEE International Conference on Industrial Technology (ICIT)
TI - Development of Methods for Coil-Based Localization by Magnetic Fields of Miniaturized Sensor Platforms in Bioprocesses
ER -
TY - CHAP
AU - Hilleringmann, Ulrich
ID - 39394
SN - 9780128189009
T2 - Nanostructured Zinc Oxide
TI - ZnO nanoparticle films as active layer for thin film transistors
ER -
TY - CONF
AU - Reker, Julia
AU - Meyers, Thorsten
AU - Vidor, Fabio F.
AU - Joubert, Trudi-Heleen
AU - Hilleringmann, Ulrich
ID - 39396
T2 - 2021 Smart Systems Integration (SSI)
TI - Complementary Inverter Circuits on Flexible Substrates
ER -
TY - CONF
AU - Reker, Julia
AU - Meyers, Thorsten
AU - Vidor, Fabio F.
AU - Joubert, Trudi-Heleen
AU - Hilleringmann, Ulrich
ID - 39388
T2 - 2021 IEEE International Conference on Flexible and Printable Sensors and Systems (FLEPS)
TI - Integration Process for Self-aligned Sub-µm Thin-Film Transistors for Flexible Electronics
ER -
TY - GEN
ID - 41288
TI - Entwicklung einer konstruktionsbasierten französischen Grammatik: ein Arbeitsbericht zum Adjektiv- und Nominalbandd
ER -
TY - BOOK
AU - Siepmann, Dirk
AU - Bürgel, Christoph
ID - 41221
TI - Grammatik des gesprochenen und geschriebenen Französisch: Das Nomen,
VL - 2
ER -
TY - GEN
ID - 41269
TI - Lexiko-grammatische Konstruktionen als Kern der Spracharbeit im Spanischunterricht, in: Hispanorama
ER -
TY - GEN
ID - 41267
TI - Hörverstehenskompetenz: Spanischstudierende auf dem Prüfstand der Abituraufgaben
ER -
TY - JOUR
AU - Burgfeld-Meise, Bianca
AU - Dehmel, Lukas
ID - 43148
JF - Zeitschrift MedienPädagogik 42
TI - Subjektwissen als Bildungsperspektive junger Erwachsener. Self-Tracking-Apps als digitale Optimierungstechnologien im Spannungsgefüge von Kontrolle und Selbstermächtigung
ER -
TY - JOUR
AU - Damm, Jannis
AU - Albiez, Matthias
AU - Göddecke, Johannes
AU - Meschut, Gerson
AU - Ummenhofer, Thomas
ID - 43159
IS - 9
JF - adhäsion KLEBEN & DICHTEN
KW - Polymers and Plastics
KW - General Chemical Engineering
KW - General Chemistry
SN - 1619-1919
TI - Dämpfungseigenschaften geklebter Verbindungen - Potenzialanalyse und Klebstoffcharakterisierung
VL - 65
ER -
TY - JOUR
AB - Der Beitrag referiert Ergebnisse studentischer Forschungsprojekte, die sich mit den Folgen der Corona-Pandemie für die berufliche Bildung, für Berufswahl, Berufsvorbereitung und Ausbildung befasst haben. Die Ergebnisse zeigen nicht nur, wie unterschiedlich Berufe und Branchen von der Krise betroffen waren und damit umgegangen sind, sondern geben auch Hinweise auf nötige Weiterentwicklungen zur Verbesserung der Resilienz von Branchen, Berufen, Betrieben und ihrer Ausbildung.
AU - Heisler, Dietmar
ID - 43179
JF - Berufsbildung. Zeitschrift für Theorie-Praxis-Dialog
KW - Pandemie
KW - Distanzlernen
KW - Berufswahl
KW - Ausbildung
SN - 00059536
TI - Berufsausbildung in der Corona-Pandemie. Befunde studentischer Forschungsprojekte
VL - 192
ER -
TY - CHAP
AU - Heisler, Dietmar
AU - Reißland, Jens
AU - Müller, Claudia
AU - Rühr, Laura
AU - Gröger, Simon
ED - Melzig, Christian
ED - Kuhlmeier, Werner
ED - Kretschmer, Susanne
ID - 43182
SN - 978-3-8474-2951-7
T2 - Berufsbildung für nachhaltige Entwicklung. Die Modellversuche 2015-2019 auf dem Weg vom Projekt zur Struktur
TI - Das Analyseraster zu Merkmalen eines nachhaltigen Lernortes für betriebliche Ausbilderinnen und Ausbilder.
ER -
TY - JOUR
AB - Im Fokus steht das Problem der Durchlässigkeit von akademischer und beruflicher Bildung im Kontext aktueller Reformen. Die Erhöhung sozialer Mobilität als Reformziel gerät darin zugunsten der Attraktivitätssteigerung von Bildungsgängen aus dem Blick. Die geringe Durchlässigkeit von Bildungsgängen wird primär als Marketingproblem thematisiert.
AU - Heisler, Dietmar
ID - 43178
JF - Berufsbildung. Zeitschrift für Theorie-Praxis-Dialog
KW - allgemeine Bildung
KW - berufliche BIldung
KW - Durchlässigkeit im Bildungssystem
SN - 00059536
TI - Berufsausbildung zwischen Attraktivitätsverlust und sozialer Ungleichheit Reformen für mehr Durchlässigkeit zwischen beruflicher und akademischer Bildung
VL - 191
ER -
TY - JOUR
AB - We show the existence of ground states in the massless spin boson model without any infrared regularization. Our proof is non-perturbative and relies on a compactness argument. It works for arbitrary values of the coupling constant under the hypothesis that the second derivative of the ground state energy as a function of a constant external magnetic field is bounded.
AU - Hasler, David
AU - Hinrichs, Benjamin
AU - Siebert, Oliver
ID - 43465
IS - 1
JF - Communications in Mathematical Physics
SN - 0010-3616
TI - On Existence of Ground States in the Spin Boson Model
VL - 388
ER -
TY - GEN
AU - Schroeter-Wittke, Harald
ID - 41089
SN - 0540–6226
T2 - Jahrbuch für Evangelische Kirchengeschichte des Rheinlandes
TI - Andrea Strübind / Klaas-Dieter Voß (Hgg.), Märtyrerbücher und ihre Bedeutung für konfessionelle Identität und Spiritualität in der Frühen Neuzeit. Interkonfessionelle und interdisziplinäre Beiträge zur Erforschung einer Buchgattung (SMHR 109), Tübingen 2019
VL - 70
ER -
TY - GEN
AU - Schroeter-Wittke, Harald
ID - 41087
SN - 0540–6226
T2 - Jahrbuch für Evangelische Kirchengeschichte des Rheinlandes
TI - Stefan Alkier (Hg.), Sola Scriptura 1517-2017. Rekonstruktionen – Kritiken – Transformationen – Performanzen (CHTh 7), Tübingen 2019
VL - 70
ER -
TY - CONF
AU - Ahmed, Qazi Arbab
ID - 29138
T2 - 2021 IFIP/IEEE 29th International Conference on Very Large Scale Integration (VLSI-SoC)
TI - Hardware Trojans in Reconfigurable Computing
ER -
TY - JOUR
AU - Schulze, Johanna
ID - 43389
JF - GGG-Magazin: DIE SCHULE für alle
TI - Einzelschulentwicklung gerecht und digital – Einblicke in die empirische Lage und Konsequenzen für die Praxis.
VL - 4
ER -
TY - BOOK
AU - Schulze, Johanna
ID - 43388
TI - Medienkonzepte zur chancengerechten Schulentwicklung. Fallstudien an Schulen mit besonders herausfordernden Schüler*innenkompositionen.
ER -
TY - JOUR
AU - Luo, Kai Hong
AU - Santandrea, Matteo
AU - Stefszky, Michael
AU - Sperling, Jan
AU - Massaro, Marcello
AU - Ferreri, Alessandro
AU - Sharapova, Polina
AU - Herrmann, Harald
AU - Silberhorn, Christine
ID - 26889
JF - Physical Review A
SN - 2469-9926
TI - Quantum optical coherence: From linear to nonlinear interferometers
ER -
TY - JOUR
AU - Lüders, Carolin
AU - Pukrop, Matthias
AU - Rozas, Elena
AU - Schneider, Christian
AU - Höfling, Sven
AU - Sperling, Jan
AU - Schumacher, Stefan
AU - Aßmann, Marc
ID - 26283
JF - PRX Quantum
SN - 2691-3399
TI - Quantifying Quantum Coherence in Polariton Condensates
ER -
TY - JOUR
AU - Bagrets, Dmitry
AU - Kim, Kun Woo
AU - Barkhofen, Sonja
AU - De, Syamsundar
AU - Sperling, Jan
AU - Silberhorn, Christine
AU - Altland, Alexander
AU - Micklitz, Tobias
ID - 26284
JF - Physical Review Research
SN - 2643-1564
TI - Probing the topological Anderson transition with quantum walks
ER -
TY - JOUR
AU - Xue, Yan
AU - Chestnov, Igor
AU - Sedov, Evgeny
AU - Kiktenko, Evgeniy
AU - Fedorov, Aleksey K.
AU - Schumacher, Stefan
AU - Ma, Xuekai
AU - Kavokin, Alexey
ID - 21362
IS - 1
JF - Physical Review Research
SN - 2643-1564
TI - Split-ring polariton condensates as macroscopic two-level quantum systems
VL - 3
ER -
TY - JOUR
AU - Jurgen von Bardeleben, Hans
AU - Cantin, Jean-Louis
AU - Gerstmann, Uwe
AU - Schmidt, Wolf Gero
AU - Biktagirov, Timur
ID - 29747
IS - 19
JF - Nano Letters
KW - Mechanical Engineering
KW - Condensed Matter Physics
KW - General Materials Science
KW - General Chemistry
KW - Bioengineering
SN - 1530-6984
TI - Spin Polarization, Electron–Phonon Coupling, and Zero-Phonon Line of the NV Center in 3C-SiC
VL - 21
ER -
TY - JOUR
AU - Slawig, Diana
AU - Gruschwitz, Markus
AU - Gerstmann, Uwe
AU - Rauls, Eva
AU - Tegenkamp, Christoph
ID - 29748
IS - 36
JF - The Journal of Physical Chemistry C
KW - Surfaces
KW - Coatings and Films
KW - Physical and Theoretical Chemistry
KW - General Energy
KW - Electronic
KW - Optical and Magnetic Materials
SN - 1932-7447
TI - Adsorption and Reaction of PbPc on Hydrogenated Epitaxial Graphene
VL - 125
ER -
TY - JOUR
AU - Jain, Mitisha
AU - Gerstmann, Uwe
AU - Schmidt, Wolf Gero
AU - Aldahhak, Hazem
ID - 40250
IS - 6
JF - Journal of Computational Chemistry
KW - Computational Mathematics
KW - General Chemistry
SN - 0192-8651
TI - Adatom mediated adsorption of N‐heterocyclic carbenes on Cu(111) and Au(111)
VL - 43
ER -
TY - JOUR
AB - High harmonic generation (HHG) from solids shows great application prospects in compact short-wavelength light sources and as a tool for imaging the dynamics in crystals with subnanometer spatial and attosecond temporal resolution. However, the underlying collision dynamics behind solid HHG is still intensively debated and no direct mapping relationship between the collision dynamics with band structure has been built. Here, we show that the electron and its associated hole can be elastically scattered by neighboring atoms when their wavelength approaches the atomic size. We reveal that the elastic scattering of electron/hole from neighboring atoms can dramatically influence the electron recombination with its left-behind hole, which turns out to be the fundamental reason for the anisotropic interband HHG observed recently in bulk crystals. Our findings link the electron/hole backward scattering with Van Hove singularities and forward scattering with critical lines in the band structure and thus build a clear mapping between the band structure and the harmonic spectrum. Our work provides a unifying picture for several seemingly unrelated experimental observations and theoretical predictions, including the anisotropic harmonic emission in MgO, the atomic-like recollision mechanism of solid HHG, and the delocalization of HHG in ZnO. This strongly improved understanding will pave the way for controlling the solid-state HHG and visualizing the structure-dependent electron dynamics in solids.
AU - Zuo, Ruixin
AU - Trautmann, Alexander
AU - Wang, Guifang
AU - Hannes, Wolf-Rüdiger
AU - Yang, Shidong
AU - Song, Xiaohong
AU - Meier, Torsten
AU - Ciappina, Marcelo
AU - Duc, Huynh Thanh
AU - Yang, Weifeng
ID - 37331
JF - Ultrafast Science
SN - 2765-8791
TI - Neighboring Atom Collisions in Solid-State High Harmonic Generation
VL - 2021
ER -
TY - JOUR
AB - AbstractMethylammonium lead iodide perovskite (MAPbI3) is renowned for an impressive power conversion efficiency rise and cost-effective fabrication for photovoltaics. In this work, we demonstrate that polycrystalline MAPbI3s undergo drastic changes in optical properties at moderate field strengths with an ultrafast response time, via transient Wannier Stark localization. The distinct band structure of this material - the large lattice periodicity, the narrow electronic energy bandwidths, and the coincidence of these two along the same high-symmetry direction – enables relatively weak fields to bring this material into the Wannier Stark regime. Its polycrystalline nature is not detrimental to the optical switching performance of the material, since the least dispersive direction of the band structure dominates the contribution to the optical response, which favors low-cost fabrication. Together with the outstanding photophysical properties of MAPbI3, this finding highlights the great potential of this material in ultrafast light modulation and novel photonic applications.
AU - Berghoff, Daniel
AU - Bühler, Johannes
AU - Bonn, Mischa
AU - Leitenstorfer, Alfred
AU - Meier, Torsten
AU - Kim, Heejae
ID - 37338
IS - 1
JF - Nature Communications
KW - General Physics and Astronomy
KW - General Biochemistry
KW - Genetics and Molecular Biology
KW - General Chemistry
KW - Multidisciplinary
SN - 2041-1723
TI - Low-field onset of Wannier-Stark localization in a polycrystalline hybrid organic inorganic perovskite
VL - 12
ER -
TY - JOUR
AU - Thong, Le Huu
AU - Ngo, Cong
AU - Duc, Huynh Thanh
AU - Song, Xiaohong
AU - Meier, Torsten
ID - 23477
JF - Physical Review B
SN - 2469-9950
TI - Microscopic analysis of high harmonic generation in semiconductors with degenerate bands
VL - 103
ER -
TY - JOUR
AB - Lithium niobate (LiNbO3), a material frequently used in optical applications, hosts different kinds of polarons that significantly affect many of its physical properties. In this study, a variety of electron polarons, namely free, bound, and bipolarons, are analyzed using first-principles calculations. We perform a full structural optimization based on density-functional theory for selected intrinsic defects with special attention to the role of symmetry-breaking distortions that lower the total energy. The cations hosting the various polarons relax to a different degree, with a larger relaxation corresponding to a larger gap between the defect level and the conduction-band edge. The projected density of states reveals that the polaron states are formerly empty Nb 4d states lowered into the band gap. Optical absorption spectra are derived within the independent-particle approximation, corrected by the GW approximation that yields a wider band gap and by including excitonic effects within the Bethe-Salpeter equation. Comparing the calculated spectra with the density of states, we find that the defect peak observed in the optical absorption stems from transitions between the defect level and a continuum of empty Nb 4d states. Signatures of polarons are further analyzed in the reflectivity and other experimentally measurable optical coefficients.
AU - Schmidt, Falko
AU - Kozub, Agnieszka L.
AU - Gerstmann, Uwe
AU - Schmidt, Wolf Gero
AU - Schindlmayr, Arno
ID - 21946
JF - Crystals
TI - Electron polarons in lithium niobate: Charge localization, lattice deformation, and optical response
VL - 11
ER -
TY - CONF
AB - Population/mixing-time-dependent two-dimensional coherent spectra are presented for exciton-polaritons in a microcavity. Theory based on dynamically-controlled truncation reveals coherent and incoherent contributions to the decay dynamics.
AU - Meier, Torsten
AU - Paul, Jagannath
AU - Rose, Hendrik
AU - Wahlstrand, Jared K
AU - Bristow, Alan D
ID - 43746
SN - 978-1-55752-308-2
T2 - Frontiers in Optics
TI - Coherent and incoherent contribution of population dynamics of semiconductor exciton-polaritons
ER -
TY - CONF
AU - Reichelt, Matthias
AU - Rose, Hendrik
AU - Kosarev, Alexander N.
AU - Poltavtsev, Sergey V.
AU - Bayer, Manfred
AU - Akimov, Ilya A.
AU - Schneider, Christian
AU - Kamp, Martin
AU - Höfling, Sven
AU - Meier, Torsten
ED - Betz, Markus
ED - Elezzabi, Abdulhakem Y.
ID - 23474
T2 - Ultrafast Phenomena and Nanophotonics XXV
TI - Controlling the emission time of photon echoes by optical freezing of exciton dephasing and rephasing in quantum-dot ensembles
VL - 11684
ER -
TY - JOUR
AU - Murzakhanov, F. F.
AU - Yavkin, B. V.
AU - Mamin, G. V.
AU - Orlinskii, S. B.
AU - von Bardeleben, H. J.
AU - Biktagirov, Timur
AU - Gerstmann, Uwe
AU - Soltamov, V. A.
ID - 29749
JF - Physical Review B
SN - 2469-9950
TI - Hyperfine and nuclear quadrupole splitting of the NV− ground state in 4H-SiC
VL - 103
ER -
TY - JOUR
AU - Aldahhak, Hazem
AU - Hogan, Conor
AU - Lindner, Susi
AU - Appelfeller, Stephan
AU - Eisele, Holger
AU - Schmidt, Wolf Gero
AU - Dähne, Mario
AU - Gerstmann, Uwe
AU - Franz, Martin
ID - 22010
JF - Physical Review B
SN - 2469-9950
TI - Electronic structure of the Si(111)3×3R30∘−B surface from theory and photoemission spectroscopy
VL - 103
ER -
TY - JOUR
AU - Rose, Hendrik
AU - Popolitova, D. V.
AU - Tikhonova, O. V.
AU - Meier, Torsten
AU - Sharapova, Polina
ID - 23478
JF - Physical Review A
SN - 2469-9926
TI - Dark-state and loss-induced phenomena in the quantum-optical regime of Λ-type three-level systems
VL - 103
ER -
TY - JOUR
AU - Belobo, Didier Belobo
AU - Meier, Torsten
ID - 23473
JF - New Journal of Physics
SN - 1367-2630
TI - Approximate nonlinear wave solutions of the coupled two-component Gross–Pitaevskii equations with spin–orbit interaction
VL - 23
ER -
TY - JOUR
AU - Nguyen, T. T. Nhung
AU - Sollfrank, T.
AU - Tegenkamp, C.
AU - Rauls, E.
AU - Gerstmann, Uwe
ID - 22881
JF - Physical Review B
SN - 2469-9950
TI - Impact of screening and relaxation on weakly coupled two-dimensional heterostructures
VL - 103
ER -
TY - JOUR
AB - Modern forming processes often allow today the efficient production of complex parts. In order to increase the sustainability of forming processes it would be favorable if the forming of workpieces becomes possible using production waste. At the Chair of Forming and Machining Technology of the Paderborn University (LUF) research is presently conducted with the overall goal to produce workpieces directly from secondary aluminum (e.g., powder and chips). Therefore, friction-based forming processes like friction spinning (or cognate processes) are used due to their high efficiency. As a pre-step, the production of semi-finished parts was the subject of accorded research work at the LUF. Therefore, a friction-based hot extrusion process was used for the full recycling or rework of aluminum chips into profiles. Investigations of the recycled semi-finished products show that they are comparable to conventionally produced semi-finished products in terms of dimensional stability and shape accuracy. An analysis of the mechanical properties of hardness and tensile strength shows that a final product with good and homogeneously distributed properties can be produced. Furthermore, significant correlations to the friction spinning process could be found that are useful for the above-mentioned direct part production from secondary aluminum.
AU - Borgert, Thomas
AU - Homberg, Werner
ID - 21635
JF - Metals
SN - 2075-4701
TI - Friction-Induced Recycling Process for User-Specific Semi-Finished Product Production
ER -
TY - CONF
AU - Moritzer, Elmar
AU - Flachmann, Felix
ID - 23746
SN - 978-1-7138-3075-7
T2 - SPE ANTEC 2021: The Annual Technical Conference for Plastic Professionals
TI - Influence of Chemical Blowing Agents on the Filling Behavior of Wood-Plastic-Composite Melts
ER -
TY - JOUR
AU - Bolenz, Lukas
AU - Ehlert, Thomas
AU - Dechert, Christopher
AU - Bertling, René
AU - Kenig, Eugeny
ID - 23789
JF - Chemical Engineering Research and Design
SN - 0263-8762
TI - Modelling of a continuous distillation process with finite reflux ratio using the hydrodynamic analogy approach
ER -
TY - CONF
AB - Driven by the CO2-emission law by the European government and the increasing costs for raw materials as well as energy, the automotive industry is increasingly using multi-material constructions. This leads to a continuous increase in the use of mechanical joining techniques and especially the self-piercing riveting is of particular importance. The reason for this is the wide range of joining possibilities as well as the high load-bearing capacities of the joints. To be able to react to changing boundary conditions, like material thickness or strength variation of the sheets, research work is crucial with regard to the increase of versatility. In this paper, a numerical study of the influences on the selfpiercing riveting process is presented. For this purpose, the influence of different process parameters such as rivet length and die depth on various quality-relevant characteristics were investigated. With the help of the design of experiment, significant influences were determined and interactions between the individual parameters are shown.
AU - Kappe, Fabian
AU - Bielak, Christian Roman
AU - Sartisson, Vadim
AU - Bobbert, Mathias
AU - Meschut, Gerson
ID - 34222
T2 - ESAFORM 2021
TI - Influence of rivet length on joint formation on self-piercing riveting process considering further process parameters
ER -
TY - CONF
AB - In many areas of product manufacturing constructions consist of individual components and metal sheets that are joined together to form complex structures. A simple and industrial common method for joining dissimilar and coated materials is clinching. During the joining process and due to the service load cracks can occur in the area of the joint, propagate due to cyclic loading and consequently lead to structural failure. For the prevention of these damage cases, first of all knowledge about the fracture mechanical material parameters regarding the original material state of the sheet metals used within the clinching process are essential.Within the scope of this paper experimental and numerical preliminary investigations regarding the fracture mechanical behavior of sheet metals used within the clinching process are presented. Due to the low thickness of 1.5 mm of the material sheets, the development of a new specimen is necessary to determine the crack growth rate curve including the fracture mechanical parameters like the threshold against crack growth ΔKI,th and the fracture toughness KIC of the base material HCT590X. For the experimental determination of the crack growth rate curve the numerical calculation of the geometry factor function as well as the calibration function of this special specimen are essential. After the experimental validation of the numerically determined calibration function, crack growth rate curves are determined for the stress ratios R = 0.1 and R = 0.3 to examine the mean stress sensitivity. In addition, the different rolling directions of 0° and 90° in relation to the initial crack are taken into account in order to investigate the influence of the anisotropy due to rolling.
AU - Weiß, Deborah
AU - Schramm, Britta
AU - Kullmer, Gunter
ID - 30675
KW - Mechanical Engineering
KW - Mechanics of Materials
KW - General Materials Science
SN - 1662-9795
T2 - Key Engineering Materials
TI - Numerical and Experimental Fracture Mechanical Investigations of Clinchable Sheet Metals Made of HCT590X
VL - 883
ER -
TY - JOUR
AB - AbstractIn addition to the classical strength calculation, it is important to design components with regard to fracture mechanics because defects and cracks in a component can drastically influence its strength or fatigue behavior. Cracks can propagate due to operational loads and consequently lead to component failure. The fracture mechanical analysis provides information on stable or unstable crack growth as well as about the direction and the growth rate of a crack. For this purpose, sufficient information has to be available about the crack location, the crack length, the component geometry, the component loading and the fracture mechanical material parameters. The fracture mechanical properties are determined experimentally with standardized specimens as defined by the guidelines of the American Society for Testing and Materials. In practice, however, especially in the context with damage cases or formed material fracture mechanical parameters directly for a component are of interest. However, standard specimens often cannot be extracted at all due to the complexity of the component geometry. Therefore, the development of special specimens is required whereby certain arrangements have to be made in advance. These arrangements are presented in the present paper in order to contribute to a holistic investigation chain for the experimental determination of fracture mechanical material parameters with special specimens.
AU - Weiß, Deborah
AU - Schramm, Britta
AU - Kullmer, Gunter
ID - 30674
JF - Production Engineering
KW - Industrial and Manufacturing Engineering
KW - Mechanical Engineering
SN - 0944-6524
TI - Holistic investigation chain for the experimental determination of fracture mechanical material parameters with special specimens
ER -
TY - JOUR
AB - Powder X-ray diffraction (XRD) patterns of ordered mesoporous CMK-8 and CMK-9 carbon materials are simulated by geometric modeling. The materials are amorphous at the atomic length scale but exhibit highly symmetric gyroidal structures at the nanometer scale, corresponding to regular, continuous nanopore systems with cubic symmetry. Their structures lead to characteristic low-angle XRD signatures. We introduce a model based on geometrical considerations to simulate CMK-8 and CMK-9 structures with variable volume fraction of carbon (vs. pore volume, i.e., variable 'pore wall thickness'). In addition, we also simulate carbon materials with variable amounts of guest species (e.g., sulfur) residing in their pores. The corresponding XRD patterns are calculated. The carbon volume fraction turns out to have a significant impact on the relative diffraction peak intensities, especially in case of CMK-9 carbon that features a bimodal porosity. Likewise, the presence of guest species in the pores may also strongly affect the relative peak intensities. Our study suggests that careful evaluation of experimental low-angle XRD patterns of (real) CMK-8 or CMK-9 materials offers an opportunity to obtain detailed information about the nanostructural properties in addition to the mere identification of the pore systems geometry.
AU - Schwind, Bertram
AU - Smått, Jan-Henrik
AU - Tiemann, Michael
AU - Weinberger, Christian
ID - 25894
JF - Microporous and Mesoporous Materials
SN - 1387-1811
TI - Modeling of gyroidal mesoporous CMK-8 and CMK-9 carbon nanostructures and their X-Ray diffraction patterns
ER -
TY - JOUR
AB - A comparison of infrared spectroscopic analytical approaches was made in order to assess their applicability for internal structure characterization of SiO2 thin films. Markers for porosity and/or disorder based on the analysis of the asymmetric stretching absorption band of SiO2 between 900−1350 cm−1 were discussed. The shape of this band, which shows a well-defined LO–TO splitting, depends not only on the inherent characteristics of the film under analysis but also on the particular geometry of the IR experiment and the specific surface selection rules of the substrate. Three types of SiO2 thin films with clearly defined porosity ranging from dense films to mesoporous films were investigated by transmission (at different incidence angles), direct specular reflection (at different angles), and diffuse reflection. Two different types of substrate, metallic and semiconducting, were used. The combined effect of substrate and specific technique in the final shape of the band, was discussed, and the efficacy for their applicability to the determination of porosity in thin SiO2 films was critically evaluated.
AU - de los Arcos, Teresa
AU - Müller, Hendrik
AU - Wang, Fuzeng
AU - Damerla, Varun Raj
AU - Hoppe, Christian
AU - Weinberger, Christian
AU - Tiemann, Michael
AU - Grundmeier, Guido
ID - 25897
JF - Vibrational Spectroscopy
SN - 0924-2031
TI - Review of infrared spectroscopy techniques for the determination of internal structure in thin SiO2 films
ER -
TY - THES
AU - Olenberg, Alexander
ID - 42812
SN - 9783843947855
TI - Untersuchung und Optimierung von strukturierten Packungen mittels CFD-Simulationen
ER -
TY - JOUR
AB - Tailor-made ordered mesoporous materials bear great potential in numerous fields of application where large interfaces are required. However, the inherent surfacechemical properties of conventional materials, such as silica, carbon or organosilica, poses some limitations with respect to their application. Surface manipulation by functionalization with chemically more reactive groups is one way to improve materials for their desired purpose. Another approach is the design of high surface-area composite materials. The surface manipulation, either by functionalization or by introducing guest species, can be performed selectively. This means that when several distinct, i.e. , hierarchical, types of surfaces or pore systems exist in a material, each of them may be chosen for manipulation. Several strategies can be identified to achieve this goal. Molecules or molecule assemblies can be utilized to temporarily protect pores or surfaces (soft protection), while manipulation occurs at the accessible sites. This approach is a recurring motive in this review and can also be applied to rigid template matrices (hard protection). Furthermore, the size of functionalization agents (size protection) and their reactivity/diffusion (kinetic protection) into the pores can also be utilized to achieve selectivity. In addition, challenges in the synthesis and characterization of selectively manipulated ordered mesoporous materials are discussed.
AU - Tiemann, Michael
AU - Weinberger, Christian
ID - 25893
JF - Advanced Materials Interfaces
SN - 2196-7350
TI - Selective Modification of Hierarchical Pores and Surfaces in Nanoporous Materials
ER -
TY - JOUR
AU - Fuchs, Christian
ID - 41431
IS - 1
JF - tripleC: Communication, Capitalism & Critique
TI - Engels@200: Friedrich Engels in the Age of Digital Capitalism
VL - 19
ER -
TY - JOUR
AU - Fuchs, Christian
AU - Dyer-Witheford, Nick
ID - 41599
JF - 国际社会科学杂志 (Journal of International Social Sciences) 2021 (9)
TI - 卡尔·马克思与互联网研究
ER -