TY - CONF AB - We demonstrate a large-scale two dimensional silicon-based optical phased array (OPA) composed of nanoantennas with circular gratings that are balanced in power and aligned in phase, required for producing desired radiation patterns in the far-field. The OPAs are numerically optimized to have an upward efficiency of up to 90%, targeting radiation concentration mainly in the field of view. We envision that our OPAs have the ability of generating complex holographic images, rendering them an attractive candidate for a wide range of applications like LiDAR sensors, optical trapping, optogenetic stimulation and augmented-reality displays. AU - Farheen, Henna AU - Strauch, Andreas AU - Scheytt, J. Christoph AU - Myroshnychenko, Viktor AU - Förstner, Jens ED - García-Blanco, Sonia M. ED - Cheben, Pavel ID - 43052 KW - tet_topic_opticalantenna T2 - Integrated Optics: Devices, Materials, and Technologies XXVII TI - Optimized silicon antennas for optical phased arrays ER - TY - JOUR AB - AU - Heck, Tamara AU - Steinhardt, Isabel AU - Rahal, Rima-Maria AU - Schubotz, Moritz AU - Scholl, Dominik AU - Behrens, Sarah ID - 43094 JF - Research Ideas and Outcomes KW - Open Science SN - 2367-7163 TI - Bootstrapping the Open Science culture: The fellowship approach VL - 9 ER - TY - JOUR AU - Black, Tobias AU - Fuest, Mario AU - Lankeit, Johannes AU - Mizukami, Masaaki ID - 43105 JF - Nonlinear Analysis: Real World Applications KW - Applied Mathematics KW - Computational Mathematics KW - General Economics KW - Econometrics and Finance KW - General Engineering KW - General Medicine KW - Analysis SN - 1468-1218 TI - Possible points of blow-up in chemotaxis systems with spatially heterogeneous logistic source VL - 73 ER - TY - JOUR AU - Wippermann, Jan AU - Meschut, Gerson AU - Koshukow, Wikentij AU - Liebsch, Alexander AU - Gude, Maik AU - Minch, Steven AU - Kolbe, Björn ID - 43154 JF - Welding in the World KW - Metals and Alloys KW - Mechanical Engineering KW - Mechanics of Materials SN - 0043-2288 TI - Correction: Thermal influence of resistance spot welding on a nearby overmolded thermoplastic–metal joint ER - TY - CONF AU - Görel, Gamze AU - Hellmich, Frank AU - Löper, Marwin Felix ID - 43177 TI - Förderung der sozialen Partizipation von Kindern im inklusiven Unterricht. Workshop auf dem 9. Paderborner Grundschultag. Thema: „Demokratie von Anfang an! Demokratie in der Grundschule erfahren, mitgestalten und reflektieren“ ER - TY - CHAP AU - Vitt, Vivian AU - Häsel-Weide, Uta ID - 43227 T2 - Mathematica Didactica, 46 TI - Reziprokes Peer-Tutoring zur Förderung von Schüler*innen mit Schwierigkeiten beim Mathematiklernen. ER - TY - CHAP AU - Häsel-Weide, Uta AU - Nührenbörger, M. ID - 43226 T2 - Mathematica Didactica, 46 TI - Inklusive Praktiken unterrichtsintegrierter Förderung im Mathematikunterricht. ER - TY - GEN AU - Rüther, Torben AU - Schmid, Hans-Joachim ID - 43236 KW - CDMA TI - CDMA: Centrifugal Differential Mobility Analyzer - Ein Messprinzip zur Bestimmung von Multidimensionalen Partikeleigenschaften (Vortrag) ER - TY - JOUR AU - Schroeter-Wittke, Harald ID - 43248 IS - 1 JF - Zeitschrift für Pädagogik und Theologie SN - 1437-7160 TI - Thorsten Knauth/Rainer Möller/Annebelle Pithan (Hg.), Inklusive Religionspädagogik der Vielfalt. Konzeptionelle Grundlagen und didaktische Konkretionen. Münster/New York 2020 VL - 75 ER - TY - GEN AU - Lutters, Nicole AU - Buckmann, Felix AU - Kenig, Eugeny Y. ID - 43280 TI - Zur experimentellen Untersuchung der Reinstoffkondensation in Kissenplatten-Wärmeübertragern ER - TY - JOUR AB - Laser structuring to improve the adhesion properties of steel substrates in fiber-metal laminates offers many advantages that are highly suitable for modern industrial requirements. Maintenance and energy costs are relatively low, it is easy to automate, and there are no by-products such as chemicals or abrasives to dispose of or recycle. This makes laser structuring a particularly environmentally friendly process, which is nowadays more important than ever. On the other hand, the process time for laser structuring is much higher than for chemical pre-treatment, for example. In past studies, the time and cost efficiency of the laser structuring process has tended to play a minor role. However, there are approaches in which laser structured surfaces are adapted to the shear stress peaks occurring within the adhesive layer, thus requiring only partial structuring of the area to be bonded, potentially saving process time. In this experimental study, electrolytically galvanized steel substrates were partially laser structured to match the shear stress distribution and then bonded to a carbon fiber-reinforced plastic. The adhesion properties achieved were characterized using shear tensile tests and compared with the properties of the fully structured ones. With the partial laser structuring, a saving of 66 % of the conventional process time was achieved while maintaining 95 % of the same shear strength. AU - Voswinkel, Dietrich ID - 43371 JF - Journal of Manufacturing Processes KW - Laser treatment Adhesive bonding Surface technology Hybrid materials TI - Application of a new strategy for time-efficient laser treatment of galvanized steel substrates to improve the adhesion properties VL - 94 ER - TY - GEN ED - Meine, Sabine ED - Otto, Arnold ED - Süßmann, Johannes ID - 35062 SN - 978-3-8260-7218-5 TI - Musiklandschaften zwischen Rhein und Weser. Pluralisierung und Verflechtung entlang des Hellwegs in der Frühen Neuzeit. Unter Mitarbeit v. Markus Lauert VL - 13 ER - TY - CONF AU - Bernemann, Sören Antonius AU - Maćkowiak, Jan AU - Maćkowiak, Jerzy AU - Kenig, Eugeny ID - 43393 TI - Computerunterstützte Strömungsuntersuchung von landwirtschaftlichen Abfällen ER - TY - CONF AU - Trentinaglia, Roman AU - Merschjohann, Sven AU - Fockel, Markus AU - Eikerling, Hendrik ID - 43395 SN - 0302-9743 T2 - REFSQ 2023: Requirements Engineering: Foundation for Software Quality TI - Eliciting Security Requirements – An Experience Report ER - TY - JOUR AU - Hanusch, Maximilian ID - 34832 IS - 21 JF - Annals of Global Analysis and Geometry KW - Lax equation KW - generalized Baker-Campbell-Dynkin-Hausdorff formula KW - regularity of Lie groups TI - The Lax Equation and Weak Regularity of Asymptotic Estimate Lie Groups VL - 63 ER - TY - CHAP AU - Grydin, Olexandr AU - Garthe, Kai-Uwe AU - Yuan, Xueyang AU - Broer, Jette AU - Keßler, Olaf AU - Králík, Rostislav AU - Cieslar, Miroslav AU - Schaper, Mirko ED - Broek, Stephan ID - 41959 SN - 2367-1181 T2 - Light Metals 2023 TI - Numerical and Experimental Investigation of Twin-Roll Casting of Aluminum–Lithium Strips ER - TY - GEN AU - Ghazal, Abdulkarim AU - Sadeghi-Kohan, Somayeh AU - Reimer, Jan Dennis AU - Hellebrand, Sybille ID - 35204 KW - WORKSHOP TI - On Cryptography Effects on Interconnect Reliability ER - TY - JOUR AU - Brosch, Anian AU - Wallscheid, Oliver AU - Böcker, Joachim ID - 43456 JF - IEEE Transactions on Power Electronics KW - Electrical and Electronic Engineering SN - 0885-8993 TI - Time-Optimal Model Predictive Control of Permanent Magnet Synchronous Motors Considering Current and Torque Constraints ER - TY - CHAP AU - Strauß, Sara ED - Mildorf, Jarmila ED - Punzi, Eilsabeth ED - Singer, Christoph ID - 43459 SN - 9780197620540 T2 - Narrative and Mental Health TI - Narrative Experiments with Medical Categorization and Normalization in B. S. Johnson's House Mother Normal ER - TY - GEN AU - Dechert, Christopher AU - Kengni Nkouemou, Augustin AU - Kenig, Eugeny Y. ID - 43111 TI - Vergleichende Untersuchung der Wirkung verschiedener Mikrostrukturen auf die Flüssigkeitsausbreitung ER - TY - JOUR AB - High-contrast slab waveguide Bragg gratings with 1D periodicity are investigated. For specific oblique excitation by semi-guided waves at sufficiently high angles of incidence, the idealized structures do not exhibit any radiative losses, such that reflectance and transmittance for the single port mode add strictly up to one. We consider a series of symmetric, fully and partly etched finite gratings, for parameters found in integrated silicon photonics. These can act as spectral filters with a reasonably flattop response. Apodization can lead to more box shaped reflectance and transmittance spectra. Together with a narrowband Fabry–Perot filter, these configurations are characterized by reflection bands, or transmittance peaks, with widths that span three orders of magnitude. AU - Hammer, Manfred AU - Farheen, Henna AU - Förstner, Jens ID - 43245 IS - 4 JF - Journal of the Optical Society of America B KW - tet_topic_waveguide SN - 0740-3224 TI - How to suppress radiative losses in high-contrast integrated Bragg gratings VL - 40 ER - TY - JOUR AU - Serino, Laura AU - Gil López, Jano AU - Stefszky, Michael AU - Ricken, Raimund AU - Eigner, Christof AU - Brecht, Benjamin AU - Silberhorn, Christine ID - 44081 IS - 2 JF - PRX Quantum KW - General Physics and Astronomy KW - Mathematical Physics KW - Applied Mathematics KW - Electronic KW - Optical and Magnetic Materials KW - Electrical and Electronic Engineering KW - General Computer Science SN - 2691-3399 TI - Realization of a Multi-Output Quantum Pulse Gate for Decoding High-Dimensional Temporal Modes of Single-Photon States VL - 4 ER - TY - BOOK AU - Ribbat, Christoph ID - 44080 TI - Breathing in Manhattan: Carola Speads - The German Jewish Gymnastics Instructor Who Brought Mindfulness to America ER - TY - CONF AB - The nonlinear optical response of quantum well excitons is investigated experimentally using polarization resolved four wave mixing, optical-pump optical-probe, and optical-pump Terahertz-probe spectroscopy. The four-wave mixing data reveal clear signatures of coherent biexcitons which concur with straight-forward polarization selection rules at the Γ point. The type-I samples show the well-established time-domain beating signatures in the transients as well as the corresponding spectral signatures clearly. The latter are also present in type-II samples; however, the smaller exciton and biexciton binding energies in these structures infer longer beating times which, in turn, are accompanied by faster dephasing of the type-II exciton coherences. Furthermore, the THz absorption following spectrally narrow, picosecond excitation at energies in the vicinity of the 1s exciton resonance are discussed. Here, the optical signatures yield the well-established redshifts and blueshifts for the appropriate polarization geometries in type-I quantum well samples also termed “AC Stark Effect”. The THz probe reveals intriguing spectral features which can be ascribed to coherent negative absorption following an excitation into a virtual state for an excitation below the 1s exciton resonance. Furthermore, the scattering and ionization of excitons is discussed for several excitation geometries yielding control rules for elastic and inelastic quasiparticle collisions. AU - Meier, Torsten AU - Stein, M. AU - Schäfer, F. AU - Anders, D. AU - Littmann, J. H. AU - Fey, M. AU - Trautmann, Alexander AU - Ngo, C. AU - Steiner, J. T. AU - Reichelt, Matthias AU - Fuchs, C. AU - Volz, K. AU - Chatterjee, S. ID - 43189 T2 - Ultrafast Phenomena and Nanophotonics XXVII TI - Experimental studies of the excitonic nonlinear response of GaAs-based type-I and type-II quantum well structures interacting with optical and terahertz fields VL - 12419 ER - TY - CONF AB - Anomalous currents refer to electronic currents that flow perpendicularly to the direction of the accelerating electric field. Such anomalous currents can be generated when Terahertz fields are applied after an optical interband excitation of GaAs quantum wells. The underlying processes are investigated by numerical solutions of the semiconductor Bloch equations in the length gauge. Excitonic effects are included by treating the manybody Coulomb interaction in time-dependent Hartree-Fock approximation and additionally also carrier-phonon scattering processes are considered. The band structure and matrix elements are obtained from a 14-band k · p model within the envelope function approximation. The random phase factors of the matrix elements that appear due to the separate numerical diagonalization at each k-point are treated by applying a smooth gauge transformation. We present the macroscopic Berry curvature and anomalous current transients with and without excitonic effects. It is demonstrated that the resonant optical excitation of excitonic resonances can significantly enhance the Berry curvature and the anomalous currents. AU - Meier, Torsten AU - Ngo, C. AU - Priyadarshi, S. AU - Duc, H. T. AU - Bieler, M. ID - 43191 T2 - Ultrafast Phenomena and Nanophotonics XXVII TI - Terahertz-induced anomalous currents following the optical excitation of excitons in semiconductor quantum wells VL - 12419 ER - TY - CONF AB - The nonlinear optical response of quantum well excitons excited by optical fields is analyzed by numerical solutions of the semiconductor Bloch equations. Differential absorption spectra are computed for resonant pumping at the exciton resonance and the dependence of the absorption changes on the polarization directions of the pump and probe pulses is investigated. Coherent biexcitonic many-body correlations are included in our approach up to third-order in the optical fields. Results are presented for spatially-direct type-I and spatiallyindirect type-II quantum well systems. Due to the spatial inhomogeneity, in type-II structures a finite coupling between excitons of opposite spins exists already on the Hartree-Fock level and contributes to the absorption changes for the case of opposite circularly polarized pump and probe pulses. AU - Meier, Torsten AU - Trautmann, Alexander AU - Stein, M. AU - Schäfer, F. AU - Anders, D. AU - Ngo, C. AU - Steiner, J. T. AU - Reichelt, Matthias AU - Chatterjee, S. ID - 43190 T2 - Ultrafast Phenomena and Nanophotonics XXVII TI - Analysis of the nonlinear optical response of excitons in type-I and type-II quantum wells including many-body correlations VL - 12419 ER - TY - JOUR AU - Meier, Torsten AU - Schäfer, F. AU - Stein, M. AU - Lorenz, J. AU - Dobener, F. AU - Ngo, C. AU - Steiner, J. T. AU - Fuchs, C. AU - Stolz, W. AU - Volz, K. AU - Hader, J. AU - Moloney, J.V. AU - Koch, S.W. AU - Chatterjee, S. ID - 43139 IS - 8 JF - Applied Physics Letters TI - Gain recovery dynamics in active type-II semiconductor heterostructures VL - 122 ER - TY - GEN AU - Meier, Torsten AU - Grisard, S. AU - Trifonov, A.V. AU - Rose, Hendrik AU - Reichhardt, R. AU - Reichelt, Matthias AU - Schneider, C. AU - Kamp, M. AU - Höfling, S. AU - Bayer, M. AU - Akimov, I.A ID - 43132 T2 - arxiv:2302.02480 TI - Temporal sorting of optical multi-wave-mixing processes in semiconductor quantum dots ER - TY - JOUR AU - Sperling, Jan AU - Agudelo, Elizabeth ID - 44050 IS - 4 JF - Physical Review A SN - 2469-9926 TI - Entanglement of particles versus entanglement of fields: Independent quantum resources VL - 107 ER - TY - JOUR AU - Sperling, Jan AU - Gianani, Ilaria AU - Barbieri, Marco AU - Agudelo, Elizabeth ID - 40477 IS - 1 JF - Physical Review A SN - 2469-9926 TI - Detector entanglement: Quasidistributions for Bell-state measurements VL - 107 ER - TY - JOUR AU - Lüders, Carolin AU - Pukrop, Matthias AU - Barkhausen, Franziska AU - Rozas, Elena AU - Schneider, Christian AU - Höfling, Sven AU - Sperling, Jan AU - Schumacher, Stefan AU - Aßmann, Marc ID - 42973 IS - 11 JF - Physical Review Letters KW - General Physics and Astronomy SN - 0031-9007 TI - Tracking Quantum Coherence in Polariton Condensates with Time-Resolved Tomography VL - 130 ER - TY - JOUR AB - We study how competition between physicians affects the provision of medical care. In our theoretical model, physicians are faced with a heterogeneous patient population, in which patients systematically vary with regard to both their responsiveness to the provided quality of care and their state of health. We test the behavioral predictions derived from this model in a controlled laboratory experiment. In line with the model, we observe that competition significantly improves patient benefits as long as patients are able to respond to the quality provided. For those patients, who are not able to choose a physician, competition even decreases the patient benefit compared to a situation without competition. This decrease is in contrast to our theoretical prediction implying no change in benefits for passive patients. Deviations from patient-optimal treatment are highest for passive patients in need of a low quantity of medical services. With repetition, both, the positive effects of competition for active patients as well as the negative effects of competition for passive patients become more pronounced. Our results imply that competition can not only improve but also worsen patient outcome and that patients’ responsiveness to quality is decisive. AU - Brosig-Koch, Jeannette AU - Hehenkamp, Burkhard AU - Kokot, Johanna ID - 44092 JF - Health Economics KW - physician competition KW - patient characteristics KW - heterogeneity in quality responses KW - fee-for-service KW - laboratory experiment TI - Who benefits from quality competition in health care? A theory and a laboratory experiment on the relevance of patient characteristics ER - TY - GEN AB - We consider a model where for-profit providers compete in quality in a price-regulated market that has been opened to competition, and where the incumbent is located at the center of the market, facing high costs of relocation. The model is relevant in markets such as public health care, education and schooling, or postal services. We find that, when the regulated price is low or intermediate, the entrant strategically locates towards the corner of the market to keep the incumbent at the low monopoly quality level. For a high price, the entrant locates at the corner of the market and both providers implement higher quality compared to a monopoly. In any case, the entrant implements higher quality than the incumbent provider. Social welfare is always higher in a duopoly if the cost of quality is low. For higher cost levels welfare is non-monotonic in the price and it can be optimal to the regulator not to use its entire budget. Therefore, the welfare effect of entry depends on the price and the size of the entry cost, and the regulator should condition the decision to allow entry on an assessment of the entry cost. AU - Hehenkamp, Burkhard AU - Kaarbøe, Oddvar M. ID - 44093 KW - Quality competition KW - Price regulation KW - Location choice KW - Product differentiation TI - Price Regulation, Quality Competition and Location Choice with Costly Relocation ER - TY - JOUR AB - We present strong enhancement of third harmonic generation in an amorphous silicon metasurface consisting of elliptical nano resonators. We show that this enhancement originates from a new type of multi-mode Fano mechanism. These ‘Super-Fano’ resonances are investigated numerically in great detail using full-wave simulations. The theoretically predicted behavior of the metasurface is experimentally verified by linear and nonlinear transmission spectroscopy. Moreover, quantitative nonlinear measurements are performed, in which an absolute conversion efficiency as high as ηmax ≈ 2.8 × 10−7 a peak power intensity of 1.2 GW cm−2 is found. Compared to an unpatterned silicon film of the same thickness amplification factors of up to ~900 are demonstrated. Our results pave the way to exploiting a strong Fano-type multi-mode coupling in metasurfaces for high THG in potential applications. AU - Hähnel, David AU - Golla, Christian AU - Albert, Maximilian AU - Zentgraf, Thomas AU - Myroshnychenko, Viktor AU - Förstner, Jens AU - Meier, Cedrik ID - 44097 IS - 1 JF - Light: Science & Applications KW - tet_topic_meta SN - 2047-7538 TI - A multi-mode super-fano mechanism for enhanced third harmonic generation in silicon metasurfaces VL - 12 ER - TY - JOUR AU - Maack, Marten ID - 44077 IS - 3 JF - Operations Research Letters KW - Applied Mathematics KW - Industrial and Manufacturing Engineering KW - Management Science and Operations Research KW - Software SN - 0167-6377 TI - Online load balancing on uniform machines with limited migration VL - 51 ER - TY - GEN AU - Mamedov, Tural AU - Schleicher, Eckhard AU - Schubert, Markus AU - Ehlert, Thomas AU - Kenig, Eugeny Y. AU - Hampel, Uwe ID - 44096 TI - Experimental analysis of ship motion effects on the performance of an absorption column equipped with structured packings ER - TY - GEN AU - Ehlert, Thomas AU - Mamedov, Tural AU - Schubert, Markus AU - Kenig, Eugeny Y. ID - 44094 TI - Charakterisierung des Einflusses neigungsinduzierter Strömungsformen mit dem Ansatz der hydrodynamsichen Analogie ER - TY - GEN AU - Ehlert, Thomas AU - Lutters, Nicole AU - Kenig, Eugeny Y. ID - 44095 TI - Modellierung des Randspalts in Strukturpackungskolonnen mit dem Ansatz der hydrodynamischen Analogien ER - TY - JOUR AU - Jende, Yvonne Kristin ID - 44137 JF - Zeitschrift für Kanada-Studien SN - 0944-7008 TI - "The Future of Canadian Studies: On Plowing a Lonely Furrow." VL - 43 ER - TY - BOOK AU - Bauer, Anna Brigitte ID - 44083 SN - 978-3-8325-5625-9 TI - Experimentelle Kompetenz Physikstudierender. Entwicklung und erste Erprobung eines performanzorientierten Kompetenzstrukturmodells unter Nutzung qualitativer Methoden VL - 352 ER - TY - GEN AU - Beule, Felix AU - Schmelzle, Lars AU - Teutenberg, Dominik AU - Possart, Gunnar AU - Meschut, Gerson AU - Mergheim, Julia ID - 44181 T2 - 23. Kolloquium: Gemeinsame Forschung in der Klebtechnik TI - Methodenentwicklung zur Simulation von hyperelastischen Klebverbindungen unter Crashbelastung ER - TY - GEN AU - Schürmann, Patrick ID - 43374 TI - A Formal Comparison of Advanced Digital Signature Primitives ER - TY - CONF AU - Kowatz, Jannik AU - Teutenberg, Dominik AU - Meschut, Gerson ID - 44183 T2 - 23. Kolloquium Gemeinsame Forschung in der Klebtechnik TI - Weiterentwicklung der induktiven Schnellhärtung von Klebverbindungen für robuste Fertigungsprozesse unter Berücksichtigung von serienrelevanten Einflussfaktoren ER - TY - JOUR AB - Microcellular wood fiber reinforced polymers offer the possibility to reduce the use of fossil raw materials. In particular, thick-walled structures with thicknesses greater than 6 mm offer a high potential for weight savings. This study investigates the cell structures and mechanical properties of injection-molded test specimens. The influence of different thicknesses (6–10 mm) along with different chemical blowing agents (endothermic, exothermic) with varying dosages (0–2 wt%) is analyzed. The investigations reveal that exothermic chemical blowing agents form finer cells consistently to thin-walled structures than endothermic ones. Higher foaming agent content leads to higher pore fractions, with many small cells coalescing into a large open-pore cell network. The mechanical properties depend mainly on the pore content of the sample. The specific tensile properties deteriorate with the use of chemical blowing agents (CFA), whereas the sandwich structure produced with compact edge layers has a positive influence on the specific flexural properties. AU - Moritzer, Elmar AU - Flachmann, Felix ID - 42515 IS - 3 JF - Journal of Cellular Plastics KW - Materials Chemistry KW - Polymers and Plastics KW - General Chemistry SN - 0021-955X TI - Morphological and mechanical properties of foamed thick-walled Wood-Plastic-Composite structures VL - 59 ER - TY - JOUR AU - Burmeister, Sascha Christian AU - Schryen, Guido ID - 42179 JF - Energy Systems TI - Distribution Network Optimization: Predicting computation times to design scenario analysis for network operators ER - TY - CONF AB - Abstract. Friction-spinning as an innovative incremental forming process enables large degrees of deformation in tube and sheet metal-forming due to a self-induced heat generation in the forming zone. This paper presents new process designs for energy and resource-efficient forming of gas cylinders by friction-spinning without the use of an external heat supply. The self-generated heat enables friction-spinning process to reduce the energy demand in the manufacture of gas cylinders, which are usually manufactured with external heat (mostly fossil fuels), by 95 %. Typical gas cylinder contours, such as flattened and spherical bottom ends and cylinder necks, are manufactured by friction-spinning of AW 6060 tubular profiles with specifically designed tool path strategies. It is shown that friction-spinning enables the manufacture of typical gas cylinder contours with sufficient wall thickness and the required gas tightness without the input of external heat. Thus, this process can contribute to an increase in the energy and resource efficiency of forming processes. AU - Dahms, Frederik AU - Homberg, Werner ID - 44035 SN - 2474-395X T2 - Materials Research Proceedings TI - Energy and Resource-efficient Forming of Gas Cylinders by Friction-Spinning ER - TY - JOUR AB - The technical importance of paraffins as phase change materials (PCM) in heat storage systems increases. Knowledge on the thermal conductivity of paraffins is necessary for the design and optimization of heat storage systems. However, for most paraffins solely the thermal conductivity of the liquid state has been sufficiently investigated. For the solid state, precise thermal conductivity data are only known for a few paraffins, while only generalized values are available for the remainder, some of which contradict each other. In this study, a measurement setup based on the modified guarded hot plate method is developed. It is used to investigate the thermal conductivity of several paraffines in the solid state, including pure n-docosane and its compounds with different types and concentrations of graphite. For n-docosane in the solid state, the thermal conductivity is determined to be 0.49 W/(m K). A particle size of 200 μm with a spherical shape turns out to be optimal to increase the thermal conductivity. This allows the thermal conductivity of a compound with 10% graphite to increase by a factor of three compared to the pure paraffin. Furthermore, significant differences to thermal conductivity data from the literature are found. AU - Paul, Andreas AU - Baumhögger, Elmar AU - Dewerth, Mats-Ole AU - Hami Dindar, Iman AU - Sonnenrein, Gerrit AU - Vrabec, Jadran ID - 43391 JF - Journal of Thermal Analysis and Calorimetry KW - Physical and Theoretical Chemistry KW - Condensed Matter Physics SN - 1388-6150 TI - Thermal conductivity of solid paraffins and several n-docosane compounds with graphite ER - TY - CONF AB - Die für die Berechnung des Energieeffizienzindex von Haushaltskältegeräten benötigten Parameter werden durch Norm-Messungen im Neuzustand der Geräte bestimmt. Aus früheren Untersuchungen ist bekannt, dass durch verschiedene technische Alterungsmechanismen der Energieverbrauch über eine Produktlebensdauer von 18 Jahren um bis zu 33 % zunehmen kann. Ziel des vom BMWi geförderten Projekts ALGE war es, die verschie-denen Ursachen und Einflussgrößen für die Alterung von Haushaltskältegeräten zu ermitteln und eine Alterungs-funktion zu bestimmen, die den zeitlichen Verlauf des zunehmenden Energieverbrauchs beschreibt. In diesem Projekt wurde das Alterungsverhalten von Haushaltskältegeräten durch 100 Normenergieverbrauchs-messungen an 32 real gealterten Geräten untersucht. Aus den gewonnenen Ergebnissen konnte eine Alterungs-funktion bestimmt werden, die den Anstieg des Energieverbrauchs beschreibt. Alle untersuchten Geräte wurden an der Universität Paderborn im Neuzustand vermessen und nach einer Laufzeit von bis zu 21 Jahren erneut geprüft. Bereits nach einem zweijährigen Betrieb konnte ein Mehrverbrauch von bis zu 11 % festgestellt werden. Über die durchschnittliche Produktlebensdauer von Haushaltskältegeräten von ca. 16 Jahren steigert sich der Energieverbrauch um durchschnittlich 27 %. Im Rahmen des Projekts wurden verschiedene Systemkomponenten, wie Isolierung und Verdichter, hinsichtlich ihres Alterungsverhaltens untersucht. Bei dem im Gehäuse als Isolierung verwendeten PUR-Schaum konnte über einen Zeitraum von 31 Monaten ein Anstieg der Wärmeleitfähigkeit von 19,5 W/(m⋅K) auf 24,5 W/(m⋅K) festge-stellt werden. Zur Untersuchung der Alterung der Verdichter wurden zuvor auf einem Kalorimeterteststand ver-messene Verdichter in Geräte eingebaut. Nach einem zweijährigen Betrieb wurden diese Verdichter wieder aus-gebaut und erneut vermessen. Hierbei konnte keine Änderung des COP festgestellt werden. Zusätzlich zu den technischen Parametern wurde der Einfluss des Verbraucherverhaltens analysiert. Hier zeigte sich, dass bis zu 33 % des Gesamtenergieverbrauchs nach einer mehrjährigen Nutzungsdauer verbraucherinduziert sein können. AU - Paul, Andreas AU - Baumhögger, Elmar AU - Elsner, Andreas AU - Reineke, Michael AU - Kasper, Tina AU - Schumacher, Daniel AU - Vrabec, Jadran AU - Hüppe, Christian AU - Stamminger, Rainer AU - Hölscher, Heike AU - Stoll, Ragnar AU - Wagner, Hendrik AU - Gries, Ulrich AU - Becker, Wolfgang ID - 43394 KW - Haushaltskältegeräte KW - Energieverbrauch KW - Alterung KW - Verdichter KW - PUR-Schaum SN - 978-3-932715-55-6 TI - Alterungsmechanismen von Haushaltskältegeräten ER - TY - JOUR AB - Abstract The accessibility to rheological parameters for concrete is becoming more and more relevant. This is mainly related to the constantly emerging challenges, such as not only the development of high-strength concretes is progressing very fast but also the simulation of the flow behaviour is of high importance. The main problem, however, is that the rheological characterisation of fresh concrete is not possible via commercial rheometers. The so-called concrete rheometers provide valuable relative values for comparing different concretes, but they cannot measure absolute values. Therefore, we developed an adaptive coaxial concrete rheometer (ACCR) that allows the measurement of fresh concrete with particles up to d max = 5.5 mm {d}_{{\rm{\max }}}=5.5\hspace{.5em}{\rm{mm}} . The comparison of the ACCR with a commercial rheometer showed very good agreement for selected test materials (Newtonian fluid, shear thinning fluid, suspension, and yield stress fluid), so that self-compacting concrete was subsequently measured. Since these measurements showed a very high reproducibility, the rheological properties of the fresh concrete could be determined with high accuracy. The common flow models (Bingham (B), Herschel–Bulkley, modified Bingham (MB) models) were also tested for their applicability, with the Bingham and the modified Bingham model proving to be the best suitable ones. AU - Josch, Sebastian AU - Jesinghausen, Steffen AU - Schmid, Hans-Joachim ID - 43034 IS - 1 JF - Applied Rheology KW - Condensed Matter Physics KW - General Materials Science SN - 1617-8106 TI - Development of an adaptive coaxial concrete rheometer and rheological characterisation of fresh concrete VL - 33 ER - TY - CONF AU - Jende, Yvonne Kristin ID - 44225 T2 - Solidarités. Réseaux – Convivialités – Confrontations/ Solidarities. Networks – Convivialities – Confrontations, 44. Annual Conference of the Association for Canadian Studies in German-Speaking Countries TI - Please Mind the Gap. Reconfiguring Solidarity through Space in Michael Nicoll Yahgulanaas' Haida Manga Art. ER -