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Zur Überwasserstabilität von Ubooten basierend auf Außenmodellversuchen und Seeverhaltensrechnungen
No full textEfficient iterative reconstruction for an MPI equilibrium model with anisotropy
No full textImage reconstruction in Magnetic Particle Imaging (MPI) typically requires a system matrix, obtained through a time-consuming calibration process. To bypass this, various model-based approaches have been explored. Recent work demonstrated successful reconstruction by adapting a Chebyshev approach with Tikhonov-regularized least squares (LS) under an equilibrium model with anisotropy. In this study, we introduce an efficient evaluation of the forward and adjoint operators for the anisotropy model, enabling the use of iterative solvers and alternative regularization methods for image reconstruction
Making last mile logistics models aware of customer choices, demand sustainability and data economy
No full textBy 2030, the rise of delivery vehicles in the ten most populated cities worldwide is expected to increase GHG emissions between 21% and 32%. This trend puts pressure on public and private stakeholders to take measures to improve the sustainability of last mile logistics in cities. The EU-project DECARBOMILE (DECARBOnize last MILE logistics) aims to develop interoperable and multimodal logistics solutions for decarbonized last mile delivery in urban contexts in the years 2022–2026. This study presents a new framework of last mile’s cause-and-effect chain to identify potential sustainable logistics solutions, hence embracing customer centricity. The latter is beyond the scope of conventional logistics management and makes it difficult to manage the subsequent drivers of last mile logistics and supply chain disruption: demand patterns and data valorization. The sustainability framework first maps the last mile challenges against the PI-oriented transport system model. With its sustainable performance criterion, the framework provides a standardized approach to prioritize actions for addressing the challenges and measuring their target impacts accordingly. As a conclusion of this study, the approach: (1) provides a standardized method to identify use cases to decarbonize the last mile logistics in different contexts, (2) supports the development of a stakeholder-focused, effective decision support system that enables to define, analyze, and compare scenarios based on sustainability targets, and (3) fosters the design and deployment of sustainable last mile systems as well as their replicability
Assignment criteria for function allocation to commercial aviation system security domains
No full textAircraft cabin management is characterized by operational and business processes. Both are defined as a logical sequence of activities that occur during the flight. While the operational process includes activities to ensure flight safety, such as take-off, cruise and landing, the business process activities are related to adding value to the customer, i.e. the passenger. They are to be certified by the authority as a part of the aircraft type certification. These processes are defined by the airline and are described as part of the airline's business model. While the scope of operational processes for passenger safety within the aircraft cabin should remain as unchanged as possible, the increasing competitive pressure on airlines is leading to a constantly rising number of services in the cabin. To prevent compromising cabin safety from increased cabin crew workload during the cruise phase, there is a growing trend toward digitizing operational and business processes. The digitized operational and business processes are leading the aircraft cabin systems to access information from different domains. The emerging need for digitalization, along with essential networking capabilities, has led to the development of an aircraft security domain model that groups functionalities based on system security considerations. For this domain model, partitioning, isolation, controlled communication, and security policies are specified. However, it lacks guidance on function allocation to specific domains. This paper addresses this gap by proposing assignment criteria for the allocation of functions to aircraft security domains, making the security domain standards easier to apply in daily aviation system development
Industry 5.0 in aircraft production and MRO: challenges and opportunities
No full textGlobally interconnecting machines, processes, and resources driven by exploring and advancing new technologies defined Industry 4.0 (I4.0), resulting in, e.g., Cyber-Physical Production Systems (CPPS). The aircraft industry particularly struggled with transforming production and Maintenance, Repair, and Overhaul (MRO) processes, replacing humans with machines and automating as well as digitalizing significant parts of their value- and non-value-adding activities. However, in the face of current social and environmental challenges, future industries will need to shift from purely technology-driven to value-driven, working sustainably with resources, including human capital. Together, these approaches constitute the idea of Industry 5.0 (I5.0). On the one hand, the aviation industry faces the challenge that even I4.0 concepts and technologies are not yet fully exploited or implemented. On the other hand, due to the specific characteristics of aircraft production and MRO as well as the environmental impact of the product, a tremendous potential arises regarding placing human well-being back into the center of adding value and decreasing environmental footprint while building an industry that is resilient and fortified against disruptions of this era. In line with the I5.0 terminology, in this work, we outline the challenges and opportunities of integrating I5.0 principles into the aircraft production and MRO industries, focusing specifically on the scope of selected use cases
Sustainability regulations for PtX projects: scope and impact analysis
No full textThe utilization of power-to-X (PtX) technologies as a substitute for fossil fuels is a key instrument in defossilizing the global economy, potentially making a significant contribution to sustainability efforts. This must be ensured or at least supported by legal measures to maximize the full sustainability potential. Thus, in recent years, regulations have been created to ensure sustainable PtX production on the one hand and to promote the use of PtX products on the other. The diversity and complexity of these regulations, differing in their scope of application, the applied instruments, and the respective sustainability requirements, among other things, create potential hurdles for PtX projects and complicate determining the respective influence on technical, economic, and environmental aspects. This review aims to summarize, classify, and assess current sustainability regulations and to evaluate the impact on potential PtX projects. The paper underscores the significance of the EU Renewable Energy Directive (REDIII) as the blueprint or reference for the legal regulations within the EU member states as well as the respective certification schemes and incentive and support schemes. The impact of sustainability criteria (power supply and GHG threshold) on PtX projects is analyzed and discussed, highlighting the importance of the electricity provision concept and sustainable carbon supply
Re-revision risk of modular and monobloc revision stems after revision hip arthroplasty
No full textAims Modular revision stem fracture is a rare but difficult complication after hip arthroplasty revision. The purpose of this German Arthroplasty Registry (EPRD)-based study was to investigate whether the overall re-revision rate and the re-revision reasons of modular revision stems compared with monobloc stems are different. Methods A total of 291 re-revisions occurring within five years after implantation of a revision stem (n = 2,039) documented in the EPRD were analyzed using Kaplan-Meier survival analysis and Cox regression. Stem type (modular: n = 1,026, monobloc: n = 1,013) and revision reason were investigated as independent variables, while BMI, sex, age, hospitals’ annual revision volume, and Elixhauser score were treated as confounding variables. Cases with an infection at index surgery were analyzed separately. Results Re-revision risk after five years was similar for either stem type (modular: 18.7% (95% CI 15.9 to 21.9); monobloc: 15.6% (95% CI 13.2 to 18.4); p = 0.200). One stem fracture of a modular revision stem was reported. The main reasons for re-revision were infection (modular/monobloc: 50%/60% of all revisions; p = 0.200), dislocation (19.8%/9.6%; p = 0.045), and loosening (12.2%/ 11.4%; p > 0.999). An Elixhauser score of 4 and above was associated with a higher hazard ratio (HR) for re-revision for either stem type (modular/monobloc: HR 2.01; p = 0.026/HR 2.44; p = 0.004), as well as a BMI category above 25/40 (modular/monobloc: HR 1.73 to 3.25; all p < 0.025/HR 3.61; p < 0.001). An infected index surgery increased the re-revision risk after one year to 26.0% (95% CI 22.2% to 30.3%) compared with 8.3% for noninfected cases (95% CI 7.0% to 9.8%) (p < 0.001) independent of stem type. Conclusion A high BMI increases the HR for revision for either stem design but not due to mechanical implant failure. Infection at the index operation increases re-revision risk significantly, and is also the dominant reason for re-revision independent of stem type
Tautomerism of a backbone protonated peptide revealed by soft X-ray action spectroscopy
No full textThe structure and reactivity of peptides can be influenced by their protonation state. Notably, protonation of the backbone can induce structural changes, such as tautomerism, shifting from the stable keto form to the enol form. This phenomenon, particularly in the backbone protonated peptide acetyl-pentaglycine, was examined using a combination of soft X-ray action spectroscopy at the nitrogen K-edge and theoretical calculations based on density functional theory (DFT). We identified a resonance at 400 eV that can be clearly attributed to π*(C=N) transitions, linked exclusively to the enol form, as no keto form structures could replicate this resonance. These findings enhanced our understanding of the effect of protonation on the structure of peptides and could be employed for future dynamic studies
Stabilization techniques and adaptive conjugate gradient solver tolerances for the finite cell method
No full textImmersed boundary methods such as the finite cell method provide a versatile tool for the analysis of structures, which are difficult to discretize in a boundary conforming manner due to their complex geometries. Using Cartesian grids and a fictitious domain approach, the effort is shifted from meshing toward the quadrature, which needs to be adapted to discontinuous integrands for cut cells, i.e., elements cut by the immersed boundary. Further, the condition number of the stiffness matrix of such discretizations is typically much larger compared to boundary fitted discretizations, making the use of iterative solvers challenging. In order to restore the performance of iterative solvers, i.e., lower the condition number of the stiffness matrix, several stabilization methods are available. In this work, we compare the performance of two stabilization methods. The classical -stabilization method uses a material with low (but non-zero) stiffness in the fictitious domain. The so called eigenvalue- or -stabilization is based on an eigendecomposition of the stiffness matrix and selectively stabilizes modes, which are associated with very low eigenvalues. Generally, both stabilization methods introduce an error, which, however, can be corrected. This work includes an investigation of such correction mechanisms for linear and nonlinear problems
A timing-robust 10b 13GS/s ADC with analog fourier transform based frequency interleaving
No full textGigahertz high-speed ADCs are highly demanded with the development of high-speed wireless, wireline and optical communication applications, where the time-interleaved architecture is commonly used with few other options. Time-interleaved ADCs, on the other hand, suffers from mismatch and timing errors among the interleaving channels. The timing errors, including sampling jitter, clock skew and bandwidth mismatch, are the fundamental limiting factor and increasingly difficult to be dealt with, especially for sampling rates up to tens to hundreds GHz, resulting in significant amount of design effort, complexity, and overhead in power and area. Historically, hybrid filter banks (HFB) were proposed to reduce the timing-error sensitivity by dividing the frequency information into multiple segments and transferring them into baseband [1]. However, the increased power and complexity have made the option impractical. The Fourier transform (FT), as the mathematical foundation of the frequency-domain analysis, performs an inherent frequency division and has been explored for channelization in the receiver front-end [2] as well as ADC [3], this characteristic makes analog Fourier transform (AFT) and frequency interleaving particularly relevant and beneficial. Analysis has shown the FT has the potential in improving timing-error robustness structurally for a high-speed sampling system [4]. However, conventional AFT is extremely complicated considering the irrational coefficient matrix and extensive clock control, mismatch and driving difficulties. As a result, there has not been a frequency interleaved ADC showing competitive performance and/or energy efficiency as compared to time-interleaved ADCs