Bochum University of Applied Sciences

The integration of electric mobility and energy systems has emerged as a key research domain in the transition toward sustainable energy and decarbonized transport, yet a systematic quantitative overview of its scientific development remains limited. This study addresses this gap by conducting a bibliometric analysis of research activities across five domains central to electric vehicle–energy system integration: central energy management systems; renewable energy, hydrogen production, and large-scale storage; industrial applications; smart energy communities, virtual power plants, and vehicle-to-X; and urban high-power charging parks with local storage. Using publication data from Web of Science and Scopus, performance analysis and science mapping techniques were applied to examine publication dynamics, thematic structures, and intellectual linkages. Results indicate strong growth and consolidation around smart grids and decentralized flexibility solutions, particularly within energy management, renewable integration, and community-based energy systems, while industrial applications and high-power charging infrastructures remain comparatively underrepresented. The findings suggest a maturing interdisciplinary field characterized by expanding connections between mobility and energy research, alongside emerging opportunities related to industrial integration, charging infrastructure, and vehicle-to-grid deployment. The study provides a data-driven overview of research trends that can support future research prioritization and inform policy and strategic planning for integrated mobility-energy systems.

Understanding energy cascades across multiple scales remains challenging in magnetospheric physics, where processes span from large fluid scales down to kinetic scales. Two-fluid simulations employing local Landau-fluid closures offer a computationally efficient alternative to kinetic simulations for modeling the multiscale plasma dynamics. These closures, derived from linear kinetic theory, approximate kinetic effects while maintaining the computational advantages of fluid descriptions. However, their theoretical validity requires the plasma to remain close to local thermodynamic equilibrium (LTE), a condition frequently violated in magnetospheric phenomena such as turbulence in the magnetosheath and reconnection outflows.We investigate the performance of two-fluid Landau-fluid models in regimes far from LTE through comparison against benchmark Vlasov simulations. Our results demonstrate that despite operating outside their formal regime of applicability, Landau-fluid closures can accurately reproduce kinetic-scale physics (with some limitations that we will highlight) when the local closure parameter is appropriately chosen. The agreement of energy spectra extends across the kinetic range, capturing the essential energy cascade and dissipation mechanisms.These findings validate Landau-fluid approaches as a robust tool for large-scale magnetospheric simulations where computational constraints prohibit kinetic treatments. This is particularly relevant for interpreting multiscale observations and resolve scale coupling in key magnetospheric regions.

Reliable characterization of crystalline geothermal reservoirs requires linking rock microstructure to effective physical properties across scales, from pore to reservoir level. Digital rock physics (DRP) provides a promising framework by combining three-dimensional imaging with numerical simulation. However, established DRP workflows for sedimentary rocks are often insufficient when applied to crystalline lithologies. Low porosity, complex mineral intergrowths, fine inclusions, and alteration textures complicate phase identification and introduce biases in predicted elastic, permeability, and thermal properties, limiting established DRP workflows for low-porosity crystalline rocks. This study presents a geologically driven workflow for a granitoid rock sample from the Frontier Observatory for Research in Geothermal Energy (FORGE) site in Utah, USA. High-resolution X-ray computed tomography (XRCT) of cylindrical core plugs (10 mm diameter, 40 mm length) at 6.9 µm voxel resolution provides the basis for digital pore-scale analysis. Multiphase segmentation, i.e., assigning gray-scale intensities in XRCT volume to specific mineral phases, was performed by integrating grayscale-based thresholding techniques with geological constraints derived from thin-section petrography and scanning electron microscopy (SEM). This integrated workflow reduces misclassification caused by overlapping gray-scale intensities, partial-volume effects at phase boundaries, and unresolved microporosity. The resulting segmentation distinguishes pore space, quartz, feldspar, ferromagnesian minerals (amphibole, biotite), titanite, and accessory phases (zircon, opaque oxides, apatite). Initial digital twin analysis shows results that deviate from laboratory measurements for porosity and the determined P- and S-wave velocities. We suspect that assigning completely intact single-crystal properties to the segmented phases may be incorrect, as the microstructure provides clear information about mechanical stresses, e.g., undulatory extinction or mineral alignment. Additionally, the analyzed subvolume (4003 with an edge length of 2.76 mm) does not yet constitute a representative volume element (RVE) relative to the coarse feldspar grain size (1-3 mm). This results in the following challenges for a DRP workflow in relation to crystalline rocks compared to established sedimentary rocks: (1) XRCT scans of larger field of views to encounter the larger minerals within the granitoid sample, (2) assigning reduced elastic properties to the individual segmented mineral phases due to microcracks and fluid inclusions, (3) Preserving high-resolution imaging to resolve the small volumes of porosity (~1.2 %). We present a refined DRP workflow that addresses these challenges through multi-scale imaging strategies and microstructure-informed elastic property assignments, validated against laboratory measurements on FORGE crystalline samples.

Seismic ambient noise analysis has become an important tool for subsurface characterization, offering a cost-effective alternative to active sources and enabling continuous monitoring. Array-based techniques such as beamforming are central to ambient noise analysis, allowing the estimation of wavefield properties such as propagation direction and phase velocity. Traditionally, beamforming has been applied either to vertical-component array data, particularly for surface-wave analysis, or to three-component (3C) seismic arrays, which allow for polarization and wave-type discrimination.More recently, distributed acoustic sensing (DAS) has emerged as a powerful tool for ambient noise studies, providing dense spatial sampling and large apertures at relatively low per-channel cost. However, DAS measurements are primarily sensitive to axial strain and can therefore be interpreted as effectively single-component observations. As a result, DAS arrays deployed along a single line cannot leverage the benefits of 3C beamforming, such as polarization analysis and wave-type identification. Conversely, sparse 3C arrays provide polarization information but are often limited in wavenumber resolution due to restricted aperture and station spacing.In this study, we develop and test a joint beamforming approach that combines DAS and 3C seismic observations in a unified framework. The joint beamformer is constructed by combining normalized beam power estimates from DAS-only and 3C-only beamforming, enhancing coherent signals that are consistent across both datasets while suppressing incoherent or aliased energy. The performance of the joint approach is evaluated using numerical simulations in layered elastic media. Systematic tests are carried out for different array geometries and station spacings to investigate their effects on aliasing, resolution, and information gain. The results show that the joint beamformer improves the stability of the results, particularly in cases where DAS-only or 3C-only beamforming suffers from aliasing or limited resolution. Finally, the method is applied to a real test dataset to demonstrate its applicability under realistic noise conditions.Our study suggests that joint DAS–3C beamforming provides a robust framework for ambient noise analysis, offering improved wavefield characterization compared to single-sensor approaches and highlighting the potential of hybrid array designs for future seismic monitoring applications

Mechanically twinned titanite in mylonites from the Sesia zone (strike-slip regime) and pseudotachylyte-bearing gneisses from the Silvretta basal thrust record the stress-strain histories at greenschist-facies conditions in the two different tectonic regimes. Twinned titanite in both fault rocks was investigated by analytical scanning electron microscopy, including electron backscatter diffraction (EBSD) and U-stage measurements. It highlights the similarities and differences in the recorded deformation history. Fine-lamellar (< 1µm) mechanical twins in titanite from the Sesia mylonites with twin planes close to {221} show densities of 0.5 µm-1. Consistent with twinned jadeite, the differential stresses indicated are on the order of 0.5 GPa. In the Silvretta fault rocks, the twin density is higher, at 2.5 µm-1 and additionally, twin planes close to { ̅1 ̅1 2} occur, indicating higher stress/strain-rate conditions, consistent with twinned amphibole and ilmenite as well as the presence of pseudotachylytes. The Silvretta fault rocks do not record subsequent creep, indicating rapidly decreasing stresses. In contrast, in the Sesia mylonites, subsequent creep of the surrounding quartz matrix at decreasing stresses resulted in sets of subparallel intragranular fractures in titanite, garnet, jadeite and zircon oriented at angles between 60° and 80° to the mylonitic foliation. The similarities in high-stress crystal plasticity in both settings, with twinning at high differential stresses, as well as the differences with pseudotachylyte formation in the Silvretta fault rocks and creep at more slowly decreasing stresses in the Sesia zone mylonites, demonstrate the importance of deformation at transient high stresses for the subsequent stress-strain history.

Ultrasound measurements are used for monitoring the structural health of concrete. The elastic waves propagating in concrete structures are attenuated by scattering and intrinsic attenuation. Both quantities have to be determined for a detailed material characterization and for realistic numerical simulations of wave propagation in such structures. We present in this paper a numerical approach to determine the intrinsic attenuation of concrete. For this purpose, a realistic digital three-dimensional concrete specimen is created that accounts for correct volume fractions of aggregates of different sizes embedded into a mortar matrix. Using a viscoelastic finite difference scheme, we perform simulations of the ultrasound wave field in these digital models with different attenuation levels. The numerical observations are compared with results from ultrasonic measurements on a sample of saturated concrete to estimate the intrinsic attenuation. Embedded sensors are used for those long-term laboratory experiments. For this saturated concrete, we obtain Q=130 in a frequency band around 60 kHz.

Background: The rising costs in the metropolitan real estate market are compelling individuals to relocate outside of the city. The anticipated financial savings, however, may be undermined by long and costly commutes; raising the question of whether this trade-off is a worthwhile proposition. This paper uses a digital model of workplace commutes, income levels and house prices in England as well as Wales, to evaluate the trade-off between (i) moving to the city centre and cycling to work versus (ii) continuing to commute by car from a residence on the periphery. Methods: An indicator has been introduced that unifies the transport and housing affordability by expanding the concept of the ‘effective speed’ to include housing costs. The effective speed itself is commonly defined as the travel distance divided by the time dedicated to the transport activity (i.e., travel duration and time given to earn the money to pay for the costs incurred). Results: If only the associated fuel and mortgage costs are considered, residing on the periphery can—for those already living there—be a cost-effective option specially in cities like Cambridge and Oxford. Yet, accounting for the total ownership costs of cars or external effects, this advantage shifts in favour of relocating to the city centre. Conclusion: This study does not negate the existence of an affordable housing crisis in urban environments, though it demonstrates that strategies to cut transport emissions can produce economic gains.