Refine
Year of publication
- 2023 (256) (remove)
Institute
- Fachbereich Gestaltung (95)
- Fachbereich Medizintechnik und Technomathematik (39)
- Fachbereich Elektrotechnik und Informationstechnik (29)
- Fachbereich Luft- und Raumfahrttechnik (24)
- ECSM European Center for Sustainable Mobility (23)
- Fachbereich Wirtschaftswissenschaften (21)
- Fachbereich Chemie und Biotechnologie (17)
- Fachbereich Energietechnik (14)
- INB - Institut für Nano- und Biotechnologien (12)
- Fachbereich Maschinenbau und Mechatronik (10)
Document Type
- Bachelor Thesis (93)
- Article (77)
- Conference Proceeding (36)
- Part of a Book (22)
- Book (11)
- Patent (3)
- Habilitation (2)
- Master's Thesis (2)
- Preprint (2)
- Talk (2)
Keywords
- Corporate Design (6)
- Editorial (6)
- Illustration (6)
- Typografie (6)
- Nachhaltigkeit (5)
- Produktdesign (5)
- Fotografie (4)
- Publikation (4)
- Design (3)
- Erscheinungsbild (3)
Zugriffsart
- weltweit (97)
- campus (47)
- bezahl (31)
- fachbereichsweit (FB4) (12)
Density reduction effects on the production of [11C]CO2 in Nb-body targets on a medical cyclotron
(2023)
Medical isotope production of 11C is commonly performed in gaseous targets. The power deposition of the proton beam during the irradiation decreases the target density due to thermodynamic mixing and can cause an increase of penetration depth and divergence of the proton beam. In order to investigate the difference how the target-body length influences the operation conditions and the production yield, a 12 cm and a 22 cm Nb-target body containing N2/O2 gas were irradiated using a 13 MeV proton cyclotron. It was found that the density reduction has a large influence on the pressure rise during irradiation and the achievable radioactive yield. The saturation activity of [11C]CO2 for the long target (0.083 Ci/μA) is about 10% higher than in the short target geometry (0.075 Ci/μA).
This thesis aims at the presentation and discussion of well-accepted and new
imaging techniques applied to different types of flow in common hydraulic
engineering environments. All studies are conducted in laboratory conditions and
focus on flow depth and velocity measurements. Investigated flows cover a wide
range of complexity, e.g. propagation of waves, dam-break flows, slightly and fully
aerated spillway flows as well as highly turbulent hydraulic jumps.
Newimagingmethods are compared to different types of sensorswhich are frequently
employed in contemporary laboratory studies. This classical instrumentation as well
as the general concept of hydraulic modeling is introduced to give an overview on
experimental methods.
Flow depths are commonly measured by means of ultrasonic sensors, also known as
acoustic displacement sensors. These sensors may provide accurate data with high
sample rates in case of simple flow conditions, e.g. low-turbulent clear water flows.
However, with increasing turbulence, higher uncertainty must be considered.
Moreover, ultrasonic sensors can provide point data only, while the relatively large
acoustic beam footprint may lead to another source of uncertainty in case of
relatively short, highly turbulent surface fluctuations (ripples) or free-surface
air-water flows. Analysis of turbulent length and time scales of surface fluctuations
from point measurements is also difficult. Imaging techniques with different
dimensionality, however, may close this gap. It is shown in this thesis that edge
detection methods (known from computer vision) may be used for two-dimensional
free-surface extraction (i.e. from images taken through transparant sidewalls in
laboratory flumes). Another opportunity in hydraulic laboratory studies comes with
the application of stereo vision. Low-cost RGB-D sensors can be used to gather
instantaneous, three-dimensional free-surface elevations, even in flows with very
high complexity (e.g. aerated hydraulic jumps). It will be shown that the uncertainty
of these methods is of similar order as for classical instruments.
Particle Image Velocimetry (PIV) is a well-accepted and widespread imaging
technique for velocity determination in laboratory conditions. In combination with
high-speed cameras, PIV can give time-resolved velocity fields in 2D/3D or even as
volumetric flow fields. PIV is based on a cross-correlation technique applied to small
subimages of seeded flows. The minimum size of these subimages defines the
maximum spatial resolution of resulting velocity fields. A derivative of PIV for
aerated flows is also available, i.e. the so-called Bubble Image Velocimetry (BIV). This
thesis emphasizes the capacities and limitations of both methods, using relatively
simple setups with halogen and LED illuminations. It will be demonstrated that
PIV/BIV images may also be processed by means of Optical Flow (OF) techniques.
OF is another method originating from the computer vision discipline, based on the
assumption of image brightness conservation within a sequence of images. The
Horn-Schunck approach, which has been first employed to hydraulic engineering
problems in the studies presented herein, yields dense velocity fields, i.e. pixelwise
velocity data. As discussed hereinafter, the accuracy of OF competes well with PIV
for clear-water flows and even improves results (compared to BIV) for aerated flow
conditions. In order to independently benchmark the OF approach, synthetic images
with defined turbulence intensitiy are used.
Computer vision offers new opportunities that may help to improve the
understanding of fluid mechanics and fluid-structure interactions in laboratory
investigations. In prototype environments, it can be employed for obstacle detection
(e.g. identification of potential fish migration corridors) and recognition (e.g. fish
species for monitoring in a fishway) or surface reconstruction (e.g. inspection of
hydraulic structures). It can thus be expected that applications to hydraulic
engineering problems will develop rapidly in near future. Current methods have not
been developed for fluids in motion. Systematic future developments are needed to
improve the results in such difficult conditions.
Die potenziellen Auswirkungen der Digitalisierung auf die Lehre sind seit langem Gegenstand ausführlicher Diskussionen innerhalb der Wirtschaftsinformatik (WI) (z. B. in Auth et al. 2021, Barton et al. 2019, Klotz et al. 2019). Nicht zuletzt der in nahezu allen Wirtschaftszweigen bestehende Mangel an qualifizierten Fachkräften lenkt den Diskurs auf einen verbesserten Zugang zu Bildung und gleichen Bildungschancen. Aus dieser Vision heraus und dem Schub der Digitalisierung entstehen Bildungskonzepte wie Open Educational Resources (OER), die gesellschaftlichen Problemen, wie dem des Fachkräftemangels, entgegenwirken sollen. Im Rahmen dieses Kurzbeitrags wird das Projekt WiLMo - "Wirtschaftsinformatik Lehr- und Lernmodule" vorgestellt. WiLMo wird im Rahmen von OERContent.nrw unter Beteiligung von sechs Hochschulen entwickelt und gefördert. Alle Projektbeteiligten arbeiten gemeinsam daran, einheitliche digitale Lehr- und Lernmaterialien im OER-Format für die Kernmodule der Wirtschaftsinformatik zu entwickeln und in garantiert hoher Qualität zur Verfügung zu stellen.
Reducing poverty, protecting the planet, and improving life on earth for everyone are the essential goals of the "2030 Agenda for Sustainable Development"committed by the United Nations (UN). Achieving those goals will require technological innovation as well as their implementation in almost all areas of our business and day-to-day life. This paper proposes a high-level framework that collects and structures different uses cases addressing the goals defined by the UN. Hence, it contributes to the discussion by proposing technical innovations that can be used to achieve those goals. As an example, the goal "Climate Actionïs discussed in detail by describing use cases related to tackling biodiversity loss in order to conservate ecosystems.
The management of knowledge in organizations considers both established long-term processes and cooperation in agile project teams. Since knowledge can be both tacit and explicit, its transfer from the individual to the organizational knowledge base poses a challenge in organizations. This challenge increases when the fluctuation of knowledge carriers is exceptionally high. Especially in large projects in which external consultants are involved, there is a risk that critical, company-relevant knowledge generated in the project will leave the company with the external knowledge carrier and thus be lost. In this paper, we show the advantages of an early warning system for knowledge management to avoid this loss. In particular, the potential of visual analytics in the context of knowledge management systems is presented and discussed. We present a project for the development of a business-critical software system and discuss the first implementations and results.
Im Verfahren gegen die Österreichische Post AG (Rs. C-300/21) befasste sich der EuGH erstmals mit dem in Art. 82 DS-GVO geregelten datenschutzrechtlichen Schadensersatzanspruch. Mit den Klarstellungen des EuGH verschieben sich die Probleme nun stärker zu den „klassischen“ Fragen des Schadensersatzrechts im Zivilprozess. Relevant sind dabei vor allem Aspekte der Darlegungs- und Beweislast und deren Besonderheiten mit Blick auf den Ersatz immaterieller Schäden. Der Beitrag fokussiert sich auf die Voraussetzungen und den dabei zu führenden Tatsachenbeweis bei der Klage des Betroffenen gegen den Verantwortlichen auf Ersatz immaterieller Schäden.
Kartellrecht vs. Datenschutzrecht: Rechtsgrundlagen für die Datenverarbeitung in sozialen Netzwerken
(2023)
The concept of energy conversion into platform chemicals using bioelectrochemical systems (BES) has gained increasing attention in recent years, as the technology simultaneously provides an opportunity for sustainable chemical production and tackles the challenge of Power-to-X technologies. There are many approaches to realize the industrial scale of BES. One concept is to equip standard bioreactors with static electrodes. However, large installations resulted in a negative influence on various reactor parameters. In this study, we present a new single-chamber BES based on a stirred tank reactor in which the stirrer was replaced by a carbon fiber brush, performing the functions of the working electrode and the stirrer. The reactor is characterized in abiotic studies and electro-fermentations with Clostridium acetobutylicum. Compared to standard reactors an increase in butanol production of 20.14±3.66 % shows that the new BES can be efficiently used for bioelectrochemical processes.