Fachbereich Ingenieurwissenschaften und Kommunikation
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- Fachbereich Ingenieurwissenschaften und Kommunikation (65)
- Institut für Technik, Ressourcenschonung und Energieeffizienz (TREE) (36)
- Internationales Zentrum für Nachhaltige Entwicklung (IZNE) (9)
- Institut für Medienentwicklung und -analyse (IMEA) (7)
- Zentrum für Innovation und Entwicklung in der Lehre (ZIEL) (4)
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- 2021 (65) (remove)
Keywords
- DGQ (6)
- Melcher (6)
- Grundwerkzeug des Qualitätsmanagements (3)
- Automatic Differentiation (2)
- Hydrogen storage (2)
- Lattice Boltzmann Method (2)
- Network simulation (2)
- Pytorch (2)
- 3D printing (1)
- ABC-Analyse (1)
The clear-sky radiative effect of aerosol-radiation interactions is of relevance for our understanding of the climate system. The influence of aerosol on the surface energy budget is of high interest for the renewable energy sector. In this study, the radiative effect is investigated in particular with respect to seasonal and regional variations for the region of Germany and the year 2015 at the surface and top of atmosphere using two complementary approaches.
First, an ensemble of clear-sky models which explicitly consider aerosols is utilized to retrieve the aerosol optical depth and the surface direct radiative effect of aerosols by means of a clear sky fitting technique. For this, short-wave broadband irradiance measurements in the absence of clouds are used as a basis. A clear sky detection algorithm is used to identify cloud free observations. Considered are measurements of the shortwave broadband global and diffuse horizontal irradiance with shaded and unshaded pyranometers at 25 stations across Germany within the observational network of the German Weather Service (DWD). Clear sky models used are MMAC, MRMv6.1, METSTAT, ESRA, Heliosat-1, CEM and the simplified Solis model. The definition of aerosol and atmospheric characteristics of the models are examined in detail for their suitability for this approach.
Second, the radiative effect is estimated using explicit radiative transfer simulations with inputs on the meteorological state of the atmosphere, trace-gases and aerosol from CAMS reanalysis. The aerosol optical properties (aerosol optical depth, Ångström exponent, single scattering albedo and assymetrie parameter) are first evaluated with AERONET direct sun and inversion products. The largest inconsistency is found for the aerosol absorption, which is overestimated by about 0.03 or about 30 % by the CAMS reanalysis. Compared to the DWD observational network, the simulated global, direct and diffuse irradiances show reasonable agreement within the measurement uncertainty. The radiative kernel method is used to estimate the resulting uncertainty and bias of the simulated direct radiative effect. The uncertainty is estimated to −1.5 ± 7.7 and 0.6 ± 3.5 W m−2 at the surface and top of atmosphere, respectively, while the annual-mean biases at the surface, top of atmosphere and total atmosphere are −10.6, −6.5 and 4.1 W m−2, respectively.
The retrieval of the aerosol radiative effect with the clear sky models shows a high level of agreement with the radiative transfer simulations, with an RMSE of 5.8 W m−2 and a correlation of 0.75. The annual mean of the REari at the surface for the 25 DWD stations shows a value of −12.8 ± 5 W m−2 as average over the clear sky models, compared to −11 W m−2 from the radiative transfer simulations. Since all models assume a fixed aerosol characterisation, the annual cycle of the aerosol radiation effect cannot be reproduced. Out of this set of clear sky models, the largest level of agreement is shown by the ESRA and MRMv6.1 models.
Turbulent compressible flows are traditionally simulated using explicit time integrators applied to discretized versions of the Navier-Stokes equations. However, the associated Courant-Friedrichs-Lewy condition severely restricts the maximum time-step size. Exploiting the Lagrangian nature of the Boltzmann equation’s material derivative, we now introduce a feasible three-dimensional semi-Lagrangian lattice Boltzmann method (SLLBM), which circumvents this restriction. While many lattice Boltzmann methods for compressible flows were restricted to two dimensions due to the enormous number of discrete velocities in three dimensions, the SLLBM uses only 45 discrete velocities. Based on compressible Taylor-Green vortex simulations we show that the new method accurately captures shocks or shocklets as well as turbulence in 3D without utilizing additional filtering or stabilizing techniques other than the filtering introduced by the interpolation, even when the time-step sizes are up to two orders of magnitude larger compared to simulations in the literature. Our new method therefore enables researchers to study compressible turbulent flows by a fully explicit scheme, whose range of admissible time-step sizes is dictated by physics rather than spatial discretization.
Off-lattice Boltzmann methods increase the flexibility and applicability of lattice Boltzmann methods by decoupling the discretizations of time, space, and particle velocities. However, the velocity sets that are mostly used in off-lattice Boltzmann simulations were originally tailored to on-lattice Boltzmann methods. In this contribution, we show how the accuracy and efficiency of weakly and fully compressible semi-Lagrangian off-lattice Boltzmann simulations is increased by velocity sets derived from cubature rules, i.e. multivariate quadratures, which have not been produced by the Gauss-product rule. In particular, simulations of 2D shock-vortex interactions indicate that the cubature-derived degree-nine D2Q19 velocity set is capable to replace the Gauss-product rule-derived D2Q25. Likewise, the degree-five velocity sets D3Q13 and D3Q21, as well as a degree-seven D3V27 velocity set were successfully tested for 3D Taylor-Green vortex flows to challenge and surpass the quality of the customary D3Q27 velocity set. In compressible 3D Taylor-Green vortex flows with Mach numbers Ma={0.5;1.0;1.5;2.0} on-lattice simulations with velocity sets D3Q103 and D3V107 showed only limited stability, while the off-lattice degree-nine D3Q45 velocity set accurately reproduced the kinetic energy provided by literature.
Off-lattice Boltzmann methods increase the flexibility and applicability of lattice Boltzmann methods by decoupling the discretizations of time, space, and particle velocities. However, the velocity sets that are mostly used in off-lattice Boltzmann simulations were originally tailored to on-lattice Boltzmann methods. In this contribution, we show how the accuracy and efficiency of weakly and fully compressible semi-Lagrangian off-lattice Boltzmann simulations is increased by velocity sets derived from cubature rules, i.e. multivariate quadratures, which have not been produced by the Gauß-product rule. In particular, simulations of 2D shock-vortex interactions indicate that the cubature-derived degree-nine D2Q19 velocity set is capable to replace the Gauß-product rule-derived D2Q25. Likewise, the degree-five velocity sets D3Q13 and D3Q21, as well as a degree-seven D3V27 velocity set were successfully tested for 3D Taylor–Green vortex flows to challenge and surpass the quality of the customary D3Q27 velocity set. In compressible 3D Taylor–Green vortex flows with Mach numbers on-lattice simulations with velocity sets D3Q103 and D3V107 showed only limited stability, while the off-lattice degree-nine D3Q45 velocity set accurately reproduced the kinetic energy provided by literature.
Design of a Medium Voltage Generator with DC-Cascade for High Power Wind Energy Conversion Systems
(2021)
This paper shows a new concept to generate medium voltage (MV) in wind power application to avoid an additional transformer. Therefore, the generator must be redesigned with additional constraints and a new topology for the power rectifier system by using multiple low voltage (LV) power rectifiers connected in series and parallel to increase the DC output voltage. The combination of parallel and series connection of rectifiers is further introduced as DC-cascade. With the resulting DC-cascade, medium output voltage is achieved with low voltage rectifiers and without a bulky transformer. This approach to form a DC-cascade reduces the effort required to achieve medium DC voltage with a simple rectifier system. In this context, a suitable DC-cascade control was presented and verified with a laboratory test setup. A gearless synchronous generator, which is highly segmented so that each segment can be connected to its own power rectifier, is investigated. Due to the mixed AC and DC voltage given by the DC-cascade structure, it becomes more demanding to the design of the generator insulation, which influences the copper fill factor and the design of the cooling system. A design strategy for the overall generator design is carried out considering the new boundary conditions.
Suitability of Current Sensors for the Measurement of Switching Currents in Power Semiconductors
(2021)
This paper investigates the impact of current sensors on the measurement of transient currents in fast-switching power semiconductors in a double pulse test (DPT environment. We review previous research that assesses the influence of current sensors on a DPT circuit through mathematical modeling. The developed selection aids can be used to identify suitable current sensors for transient current measurements of fast-switching power semiconductors and to estimate the error introduced by their insertion into the DPT circuit. Afterwards, this analysis is extended by including further elements from real DPT applications to increase the consistency of the error estimation with practical situations and setups. Both methods are compared and their individual advantages and drawbacks are discussed. Finally, a recommendation on when to use which method is derived.
Die nationale Politik- und Forschungsstrategie Bioökonomie sieht eine Transformation der Wirtschaft vor, bei der die Verwendung fossiler Rohstoffe zunehmend durch den Einsatz nachwachsender Rohstoffe ersetzt wird. Der Einsatz biobasierter Kunststoffe soll dabei gefördert werden. Erste Analysen der Berichterstattung zu Biokunststoffen im Rahmen einer Pilotstudie ergaben, dass der Grundgedanke biologisch abbaubarer Kunststoffe breite Zustimmung im öffentlichen Diskurs erfährt. Abseits der soziopolitischen Diskursebene entwickelt sich jedoch eine medial geführte Diskussion um erhebliche Probleme mit den Stoffen in der Abfallwirtschaft. Die Gefahr besteht nun, dass diese Haltung verbreitet durch die Massenmedien auf die öffentliche Meinung abfärbt. Mangelnde öffentliche Akzeptanz könnte den Erfolg von innovativen Biokunststoff-Produkten gefährden.
Im Interview mit Florian Kluge und Daniel Lohmann geht es um Interventionen als Teil einer Phase Null. Die beiden Architekturprofessoren der Alanus-Hochschule in Alfter und der TH Köln sehen die Intervention als Schnittstelle zwischen Architektur und Gesellschaft.
‚Making Media‘
(2021)
Die digitale Universität
(2021)
Die digitale Universität muss als eine Form des Erscheinens ihrer Mitglieder in spezifischen Räumen und Handlungen verstanden werden. Die Verhandlung ihrer Bedingungen ist von brennender Aktualität: Das Feuer, das die Idee der digitalen Universität entfacht, hat das Potential, die apriorische Ebene von Universität zu verabschieden und ihre neue Setzung zu veranlassen.
Die Transformationen der Wissenschaft, ihrer Systeme und Ordnungen fokussiert sich meist auf eine Politik des Digitalen beziehungsweise eine Politik der Digitalität. Durch die jüngsten Ereignisse, die auch die Universität in eine Krisen- und Ausnahmesituation bringen, gewinnt dieser Aspekt eine besondere Brisanz. Die unumgängliche Entwicklung neuer Lehr- und Forschungsformate führt zu einem grundlegenden Strukturwandel der Universität. Diese Frage von philosophischer oder universitätstheoretischer Brisanz, muss ein ernsthaftes Nachdenken über die Idee der digitalen Universität anstoßen. Digitalität und Universität können nicht länger als voneinander getrennte und unveränderliche Begriffe und Phänomene aufgefasst werden, denn sie sind in ihrer Kombination intrinsisch miteinander verbunden. (Verlagsangaben)
Digitale Medienkompetenz
(2021)
Die Kommunikation der Gegenwart ist dominant digital geleitet. Die Benutzung der Zeichen ist hier an mediale Artefakte gebunden, denen dabei das Kriterium des Mikroformatischen sowohl im Hinblick auf ihre Objektivationen als auch in Hinsicht auf ihre Inhalte zukommt. Der Beitrag nimmt diese Beobachtung zum Ausgang, um am Beispiel von WhatsApp eine Kommunikationspraktik medienästhetisch zu betrachten, die ihrerseits vehement die Gegenwärtigkeit der Kommunikation bestimmt.
What is Design Theory?
(2021)
Animal models are often needed in cancer research but some research questions may be answered with other models, e.g., 3D replicas of patient-specific data, as these mirror the anatomy in more detail. We, therefore, developed a simple eight-step process to fabricate a 3D replica from computer tomography (CT) data using solely open access software and described the method in detail. For evaluation, we performed experiments regarding endoscopic tumor treatment with magnetic nanoparticles by magnetic hyperthermia and local drug release. For this, the magnetic nanoparticles need to be accumulated at the tumor site via a magnetic field trap. Using the developed eight-step process, we printed a replica of a locally advanced pancreatic cancer and used it to find the best position for the magnetic field trap. In addition, we described a method to hold these magnetic field traps stably in place. The results are highly important for the development of endoscopic tumor treatment with magnetic nanoparticles as the handling and the stable positioning of the magnetic field trap at the stomach wall in close proximity to the pancreatic tumor could be defined and practiced. Finally, the detailed description of the workflow and use of open access software allows for a wide range of possible uses.
Introduction: Chronic pain is a frequent severe disease and often associated with anxiety, depression, insomnia, disability, and reduced quality of life. This maladaptive condition is further characterized by sensory loss, hyperalgesia, and allodynia. Blue light has been hypothesized to modulate sensory neurons and thereby influence nociception.
Objectives: Here, we compared the effects of blue light vs red light and thermal control on pain sensation in a human experimental pain model.
Methods: Pain, hyperalgesia, and allodynia were induced in 30 healthy volunteers through high-density transcutaneous electrical stimulation. Subsequently, blue light, red light, or thermal control treatment was applied in a cross-over design. The nonvisual effects of the respective light treatments were examined using a well-established quantitative sensory testing protocol. Somatosensory parameters as well as pain intensity and quality were scored.
Results: Blue light substantially reduced spontaneous pain as assessed by numeric rating scale pain scoring. Similarly, pain quality was significantly altered as assessed by the German counterpart of the McGill Pain Questionnaire. Furthermore, blue light showed antihyperalgesic, antiallodynic, and antihypesthesic effects in contrast to red light or thermal control treatment.
Conclusion: Blue-light phototherapy ameliorates pain intensity and quality in a human experimental pain model and reveals antihyperalgesic, antiallodynic, and antihypesthesic effects. Therefore, blue-light phototherapy may be a novel approach to treat pain in multiple conditions.
Der Einsatz von Remote-Laboren in ingenieurwissenschaftlichen Studiengängen ermöglicht Studierenden an einigen Hochschulen die ortsunabhängige Nutzung von Laboren, Maschinen und Robotern. Remote-Labore eignen sich in besonderer Weise dafür, den digitalisierungsbedingten Anforderungen und dem Qualifikationsbedarf aus Wirtschaft und Industrie zu begegnen. Die Onlinebedienung von Laboren bietet viele Ansatzpunkte für den Erwerb digitaler Kompetenzen, wie beispielsweise das Sammeln und Analysieren von Big Data, das Entwickeln geeigneter Schnittstellen für den Onlinezugriff oder den korrekten Einsatz zur Verfügung stehender softwarebasierter Messtechnik. Auch während der Coronapandemie im Sommersemester 2020, als der reguläre Zugang zu Laboren aufgrund der Kontaktbeschränkungen nicht erlaubt war, ermöglichten Remote-Labore den Studierenden praktische Erfahrungen. Jedoch stellen nicht nur die didaktischen, sondern auch die technischen und organisatorischen Aspekte ingenieurwissenschaftliche Studiengänge bei der Umsetzung von Remote-Laboren vor anspruchsvolle Aufgaben. Der nachfolgende Beitrag greift diese Aspekte auf und beschreibt anhand ausgewählter Beispiele, wie die Umsetzung und Integration von Remote-Laboren in Studium und Lehre gelingen kann, aber auch welche Herausforderungen nach wie vor bestehen.
Start-ups als Arbeitgeber
(2021)
Sie sind im Bereich Qualitätsmanagement tätig und haben die Aufgabe bekommen, ein Problem systematisch zu untersuchen und methodisch zu lösen? Sie haben zu viele Aufgaben und wissen nicht, wie Sie diese priorisieren sollen? Oder haben Sie zu begrenzte Ressourcen, um alle Reklamationen gleichzeitig bearbeiten zu können? Oder wissen nicht, wie Sie einen bestimmten Prozess in seinen Grenzen zielführend verbessern können?
ISHIKAWA Diagramm
(2021)
In diesem Video wird der Aufbau und Nutzen eines Fischgräten-Diagramms zur Visualisierung von Ursachen oder Einflüssen auf eine Wirkung (Problem) oder ein Ziel (Lösung) gezeigt.
Die Vorteile liegen in der stammbaumähnlichen Darstellung aller möglichen Ursachen oder Einflüsse als Übersichtssammlung und in der fallweisen Eingrenzungsmöglichkeit je nach Relevanzeinschätzung.
Ablaufdiagramm
(2021)
In diesem Video werden Aufbau, Funktion und Nutzen eines Ablaufdiagrammes als Grundwerkzeug des Qualitätsmanagements gezeigt. Diese bilden die Grundlage für die Visualisierung der definierten und einzuhaltenden Reihenfolge eines Ablaufes für Algorithmen, Programme, Prozesse, Verfahren oder Projekte.
Brainstorming
(2021)
Qualitätsregelkarte
(2021)
PARETO-Diagramm
(2021)
Korrelationsdiagramm
(2021)
Histogramm
(2021)
Datensammelblatt
(2021)
In contrast to the German power supply, the energy supply in many West African countries is very unstable. Frequent power outages are not uncommon. Especially for critical infrastructures, such as hospitals, a stable power supply is vital. To compensate for the power outages, diesel generators are often used. In the future, these systems will increasingly be supplemented by PV systems and storage, so that the generator will have to be used less or not at all when needed. For the design and operation of such systems, it is necessary to better understand the atmospheric variability of PV power generation. For example, there are large variations between rainy and dry seasons, between days with high and low dust levels - caused by sandstorms (harmattan) or urban air pollution.
Nur maximal ein Fünftel aller Menschen in Deutschland, die Maschinen entwickeln, technische Innovationen vorantreiben, optimieren oder reparieren, sind weiblich. Der Anteil von Frauen in technischen Berufen liegt derzeit bei etwa 20 Prozent (1). Vergleichbar niedrig ist auch die Zahl der Journalistinnen, die sich technischen Themen verschrieben haben. Technik und auch der Technikjournalismus sind hierzulande immer noch Männerdomänen.
Die Kunst, Kunst zu zeigen
(2021)
Atomic oxygen in the mesosphere and lower thermosphere measured by terahertz heterodyne spectroscopy
(2021)
Atomic oxygen is a main component of the mesosphere and lower thermosphere (MLT). The photochemistry and the energy balance of the MLT are governed by atomic oxygen. In addition, it is a tracer for dynamical motions in the MLT. It is difficult to measure with remote sensing techniques. Concentrations can be inferred indirectly from the oxygen air glow or from observations of OH, which is involved in photochemical processes related to atomic oxygen. Such measurements have been performed with several satellite instruments such as SCIAMACHY, SABER, WINDII and OSIRIS. However, the methods are indirect and rely on photochemical models and assumptions such as quenching rates, radiative lifetimes, and reaction coefficients. The results are not always in agreement, particularly when obtained with different instruments.
An der H-BRS, einer Hochschule für Angewandte Wissenschaften mit ca. 9.000 Studierenden, wurde die OER-Kultur bewusst als Teil der Strategie zur Digitalisierung der Lehre in drei Schritten etabliert: (1) Gemeinsame Strategiebildung als Teil eines partizipativ erarbeiteten Hochschulentwicklungsplans: Verankerung von OER in der Digitalisierungsstrategie. (2) Basierend auf der Vernetzung der Expertinnen und Experten erfolgreiche Einwerbung von OER-Projekten, die exemplarisch vorgestellt werden. (3) Dauerhafte strategische Verankerung, basierend auf kontinuierlicher interner und externer Netzwerkarbeit, Etablierung von digitalen Austauschplattformen für die Lehrenden, Transfer des OER-Gedankens (Kooperation, Austausch, Mehrfachnutzen) auf die Hochschuldidaktik sowie regelmäßige Ausschreibungen von Fördermaßnahmen.
In this study, we investigate the thermo-mechanical relaxation and crystallization behavior of polyethylene using mesoscale molecular dynamics simulations. Our models specifically mimic constraints that occur in real-life polymer processing: After strong uniaxial stretching of the melt, we quench and release the polymer chains at different loading conditions. These conditions allow for free or hindered shrinkage, respectively. We present the shrinkage and swelling behavior as well as the crystallization kinetics over up to 600 ns simulation time. We are able to precisely evaluate how the interplay of chain length, temperature, local entanglements and orientation of chain segments influences crystallization and relaxation behavior. From our models, we determine the temperature dependent crystallization rate of polyethylene, including crystallization onset temperature.