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A New Numerical Method for Scalar Eigenvalue Problems in Heterogeneous, Dispersive, Sign-Changing Materials
No full textWe consider time-harmonic scalar transmission problems between dielectric and dispersive materials with generalized Lorentz frequency laws. For certain frequency ranges such equations involve a sign-change in their principle part. Due to the resulting loss of coercivity properties, the numerical simulation of such problems is demanding. Furthermore, the related eigenvalue problems are nonlinear and give rise to additional challenges. We present a new finite element method for both of these types of problems, which is based on a weakly coercive reformulation of the PDE. The new scheme can handle -interfaces consisting piecewise of elementary geometries. Neglecting quadrature errors, the method allows for a straightforward convergence analysis. In our implementation we apply a simple, but nonstandard quadrature rule to achieve negligible quadrature errors. We present computational experiments in two and three dimensions both for source and for eigenvalue problems. They confirm the stability and convergence of the new scheme
Ensuring Reliability in Practice: An Exploratory Interview Study on Challenges, Trends, and Optimization Potentials
No full textEnsuring the reliability of technical products is an essential part of modern product development processes. In the face of increasing complexity and variant diversity, companies are faced with numerous challenges. This paper presents the results of an explorative interview study conducted in various industries and company sizes. The aim was to analyze current practices, challenges, and potential for optimization in reliability assurance, especially for variant management. The results show amongst others that digital technologies, such as AI and digital twins, as well as a stronger integration of reliability into the product development process are key starting points for the future
Konzepte zur netzunabhängigen Energieversorgung für eine alternative Sicherung von Bahnübergängen
No full textAutomatic generation of thermal point clouds from TIR images and LiDAR point clouds
No full text3D thermal models are associated with building inspection and energy efficiency evaluation. Fusing Thermal infrared (TIR) images with MLS (Mobile Laser scanning) point clouds enables the generation of thermal point clouds, which combine detailed geometric data with thermal attributes at each 3D point. RGB images are typically used to recon-
struct a 3D point cloud and apply thermal textures to the model. Therefore, the generated thermal point cloud heavily relies on accurate RGB reconstruction and scale estimation. In this contribution, we introduce a novel image-feature alignment method to directly co-register TIR images with MLS point clouds. The intensity images are generated
from the point clouds, and corresponding feature points are matched with the TIR images. With the estimated corresponding points, the pose can be calculated, and the thermal textures are projected onto the MLS point clouds for thermal point cloud generation. Our method achieves results comparable to manual labeling with a projection error of RMSE 3.4 pixels, offering an efficient and reliable solution to generate 3D thermal models for building energy evaluations
Geochemistry and mineralogy of neoproterozoic exotic minerals-bearing post-collisional A-type granites of Jebel Qutn intrusion, Arabian shield, Saudi Arabia
No full textThe Jabal Qutn intrusion (JQI) is a Late Ediacaran post-collisional granitic intrusion in the northeastern part of the Arabian Shield, the western extension of the Neoproterozoic Arabian-Nubian Shield (ANS). The study area is dominated by Neoproterozoic rocks including sedimentary units of the Murdama group, granodiorites, and A-type granites. The latter form a ring complex that consists of an inner core of alkali feldspar granite and an incomplete outer zone of syenogranite with gradational contacts between them. The Qutn granites are mainly composed of feldspars, micas and quartz and contain a large variety of accessory phases including zircon, allanite, thorite, topaz, titanite, waimirite-(Y), bastnäsite, Nb-Ta oxides (columbite, qitianlingite and nioboaeschynite), wolframite, pyrochroite, apatite, and gold alloys (Au contents of 60–80 wt%). Rare mineral species such as qitianlingite and nioboaeschynite-(Y) are recorded for the first time in the whole ANS. In case of waimirite-(Y) the study area represents the third reported occurrence in the world. The granites are highly evolved (SiO = 72.69–76.65 wt%), and exhibit almost identical chondrite-normalized rare-earth elements patterns with slight enrichment in LREE compared to HREE [(La/Lu) = 1.24–2.92] and prominent negative Eu anomalies (Eu/Eu* = 0.04–0.13). They show geochemical characteristics of anorogenic granites and continuous compositional trends for both major and trace elements, indicating a common source, i.e. partial melting of juvenile crust, followed by extensive fractional crystallization of feldspars, apatite, and Fe-Ti oxides associated with minor crustal contamination. The granites were emplaced at shallow depths (< 6 km) with their estimated crystallization temperatures ranging between ca. 780 and 850 °C. The late formation of F-rich minerals (topaz, fluorite, waimirite-(Y)) implies a F-rich composition of the parental magma with strong late-magmatic F- and REE-enrichment. Textural characteristics provide evidence for a strong metasomatic alteration in the late-magmatic stage that mainly occurred in the apical and marginal parts of the alkali feldspar granite, with the hydrothermal solutions being concentrated in the upper part of the magma chamber before complete crystallization of granitic magm
Printed origami thermoelectric generator achieves > 20 Wm from low-grade heat via material and process design
No full textPrinting facilitates low-cost thermoelectric generators to power battery-free internet-of-things devices, wearables, and Industry 4.0 systems. However, scaling up requires printable thermoelectric materials with good mechanical properties and high performance. Here, we report a high-performance Ag(SeS)-based n-type printed thermoelectric film through a combination of engineering non-stoichiometric defects and sulfur substitution. An optimal sulfur substitution of 2 at. % facilitates an excellent flexibility and a power factor of~16 μWcm K at 360 K, a 65 % increase compared to a pristine AgSe film. A fully printed origami-thermoelectric generator produces a maximum power output of 907 μW at a temperature difference of 80 K. A record-high power density of 21 W m (corresponding to 800 μW g as a weightnormalized power density) is achieved, twice that of previously reported origami-thermoelectric generators. These results highlight cost-effective manufacturing of thermoelectric generators with the capability to power next-generation autonomous electronic devices
Data from Bremer et al. (2026)
No full textData part of the research article entitled: Participatory monitoring in geothermal projects: a combined socio‑geophysical approach to seismicity, risk perception and acceptability (Bremer et al., 2026
Sustainable and safe concepts for climate-friendly shipping. TAB-Fokus
No full textMaritime shipping accounts for around 3% of global greenhouse gas emissions and approximately 80% of global freight transport. International and European climate targets, particularly within the framework of the International Maritime Organization (IMO) and the European Union, aim to make the sector largely climate-neutral by 2050. The long-term climate targets for the shipping sector can only be achieved through the parallel development of renewable fuels, shipbuilding and operational efficiency measures, as well as the construction of suitable infrastructure. This must be accompanied by the further refinement of the international and European regulatory framework. Transforming the maritime shipping sector requires the coordinated efforts of various stakeholders, such as ship operators, fuel manufacturers, port operators, shipyards, suppliers, investors, and regulatory authorities.
The policy brief TAB-Fokus offers a compact overview of the content and results of our TA analyses for a climate-friendly shipping on four pages. (See web version and full report in German related below)