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Influence of electron beam modulation on deposition characteristics in directed energy deposition–electron beam additive manufacturing (DED-EB) of titanium
No full textDirected energy deposition–electron beam (DED-EB) additive manufacturing is a highly promising process for the fabrication of titanium components, offering high deposition rates and precise process control under vacuum conditions. However, optimizing the deposition characteristics, such as dimensional accuracy, surface quality, and layer uniformity, remains a key challenge, partly due to the complex dynamics of heat input and melt pool behavior. This study examines the influence of electron beam modulation on these deposition characteristics by systematically varying beam deflection parameters, including frequency and pattern, during the wire-based additive manufacturing of titanium. The effects of beam modulation on wire melting, melt pool stability, layer formation, and overall build geometry were thoroughly evaluated. The results demonstrate that carefully controlled electron beam modulation enables significant improvements in deposition stability, surface finish, and control over geometric features, thereby enhancing process reliability and enabling the production of near-net-shape titanium components. Notably, a parameter set consisting of a circular beam deflection at an oscillation frequency of 500Hz and an overfocus setting of + 40 mA effectively minimized surface ripples and waviness, thereby enhancing process stability and yielding defect-free components. These insights contribute to advancing DED-EB as a viable solution for applications where high geometric accuracy and process efficiency are demanded
Optimizing qubit control pulses for state preparation
No full textIn the burgeoning field of quantum computing, the precise design and optimization of quantum pulses are essential for enhancing qubit operation fidelity. This study focuses on refining the pulse engineering techniques for superconducting qubits, employing a detailed analysis of square and Gaussian pulse envelopes under various approximation schemes. We evaluated the effects of coherent errors induced by naive pulse designs. We identified the sources of these errors in the Hamiltonian model’s approximation level. We mitigated these errors through adjustments to the external driving frequency and pulse durations, thus implementing a pulse scheme with stroboscopic error reduction. Our results demonstrate that these refined pulse strategies improve performance and reduce coherent errors. Moreover, the techniques developed herein are applicable across different quantum architectures, such as ion-trap, atomic, and photonic systems
„Blindterni“ – ein inklusives Spiel aus dem 3D-Drucker
No full textMit „Blindterni" wird ein inklusives Spiel für Menschen mit Sehbehinderung nach der Methode Design Thinking entwickelt. Für die Fertigung wird ein verbreitetes und günstiges additives Verfahren gewählt. Iterationsschleifen bei Entwicklung und Testung sorgen dabei für eine hohe Nutzerakzeptanz. Die Resonanz der Testgruppe einer Schule mit dem Förderschwerpunkt Sehen ist durchweg positiv und trägt ihrerseits maßgeblich zur Verbesserung bei. Das Spiel verfolgt den opensource-Ansatz und kann so von enthusiastischen Laien mit Zugang zu einem 3D Drucker einfach und günstig gefertigt werden
Exploring the Effects of Cybersecurity Awareness and Decision-Making Under Risk
No full textAbstract
This paper challenges the conventional assumption in cybersecurity that users act as rational actors. Despite numerous technical solutions, awareness campaigns, and organizational strategies aimed at bolstering cybersecurity, these often overlook the prevalence of non-rational user behavior. Our study, involving a survey of 208 participants, empirically demonstrates this aspect. We found that a significant portion of users (55.3%) would accept a substantial risk (35%) to click on a potentially malicious link or attachment. This propensity increases to 61% when users are led to believe there is a 65% chance of facing no adverse consequences. To address this irrationality, we explored the efficacy of nudging mechanisms within email systems. Our qualitative user study revealed that incorporating a simple colored nudge in the email intably enhance the ability of users to discern malicious emails, improving decision-making accuracy by an average of 10%
Femtosecond laser-induced surface structuring of porous nickel substituting anodic catalyst layers for alkaline oxygen evolution reaction
No full textFemtosecond laser-induced nano structuring offers a novel approach to enhance the performance of porous transport layers (PTLs) in anion-exchange membrane water electrolysis. By applying ultrashort laser pulses to nickel felts, distinct surface morphologies were generated, including high-spatial-frequency laser-induced periodic surface structures (HSFL-LIPSS), irregular ablated surfaces, and hybrid structures. Surface area analysis revealed increases of up to 4-fold for LIPSS, 6-fold for hybrid structures (LIPSS+Ablation), and 9-fold for ablated surfaces compared to untreated fibers. Electrochemical testing showed reduced overpotentials for laser-treated samples, comparable to state-of-the-art electrodes despite the absence of catalyst layers. Overpotentials could be reduced by up to 6.5 % at 10 mA cm−2 and by up to 9.6 % at 100 mA cm−2 compared to the unprocessed felt. Notably, ablated structures, with the highest surface areas, exhibited microcavities that may entrap oxygen bubbles, limiting active site and reaction rates. The LIPSS structures demonstrated the lowest activation losses and highest current density (1.32 A cm⁻² at 2.0 V) due to their periodic morphology and enhanced electrolyte flow, representing a 17 % improvement at 2.0 V compared to the untreated felts. Moreover, Tafel slopes down to 66 mV dec−1 denote a performant kinetic while oxidation charge measurements revealed pronounced peaks for laser-treated samples, with ablated surfaces achieving the highest charge of 16.76 ± 1.64 C cm⁻². Chronopotentiometry revealed the LIPSS structures showing the highest resistance to degradation among the structured samples.
These findings suggest femtosecond laser nano structuring as a promising method to improve PTL performance. Further application of catalyst layers could amplify the electrochemical efficiency of these advanced materials
Vibration-Based Non-Contact Activity Classification for Home Cage Monitoring Using a Tuned-Beam IMU Sensing Device
No full textAbstract
This work presents a vibration-based non-contact monitoring method to classify the physical activity of a mouse inside a home cage. A novel tuned-beam sensing device is developed to measure low-amplitude activity-induced cage vibrations. The sensing device uses a mechanical beam structure to enhance a six-axis IMU that increases the signal-to-noise ratio (SNR) by 20 to 40 times in a relevant environment. A sophisticated classification algorithm is developed to process vibration sequences with a variable time frame that utilizes multi-level discrete wavelet transformation (MLDWT) to extract time–frequency features and optimize signal properties. The extracted features are classified by a convolutional neural network–long short-term memory (CNN-LSTM) machine learning model to determine the activity class. The ground truth is obtained with a camera-based system using EthoVision XT from Noldus and a custom post-processor. The method is developed on a dataset containing 300 h of vibration measurements with camera-based reference and includes two separate home cages and two individual mice. The method classifies the activity types Resting, Stationary Activity, Walking, Activity in Feeder, and Drinking with an accuracy of 86.81% and an average F1 score of 0.798 using a 9 s time frame. In long-term monitoring, the proposed method reproduces behavioral patterns such as sleep and acclimatization as accurately as the reference method, enabling home cage monitoring in the husbandry environment with a low-cost sensor
A metatranscriptomic exploration of fungal and bacterial contributions to allochthonous leaf litter decomposition in the streambed
No full textThe decomposition of organic matter is essential for sustaining the health of freshwater ecosystems by enabling nutrient recycling, sustaining food webs, and shaping habitat conditions, which collectively enhance ecosystem resilience and productivity. Bacteria and fungi play a crucial role in this process by breaking down coarse particulate organic matter (CPOM), such as leaf litter, into nutrients available for other organisms. However, the specific contribution of bacteria and their functional interactions with fungi in freshwater sediments have yet to be thoroughly explored. In the following study, we enriched organic matter through the addition of alder (Alnus glutinosa) leaves into artificial stream channels (AquaFlow mesocosms). We then investigated enzyme expression, metabolic pathways, and community composition of fungi and bacteria involved in the degradation of CPOM through metatranscriptomics and amplicon sequencing. Enzymes involved in the degradation of lignin, cellulose, and hemicellulose were selectively upregulated with increased organic matter. Analysis of ITS and 16S rRNA gene sequences revealed that during decomposition, fungal communities were predominantly composed of Basidiomycota and Ascomycota, while bacterial communities were largely dominated by Pseudomonadota and Bacteroidota. The similar gene expression patterns of CPOM degradation related enzymes observed between bacteria and fungi indicate potential functional interaction between these microbial groups. This correlation in enzyme expression may indicate that bacteria and fungi are jointly involved in the breakdown of coarse particulate organic matter, potentially through mutualistic interaction. This study uncovers the specific enzymatic activities of bacteria and fungi and the importance of microbial interactions in organic matter decomposition, revealing their central role in facilitating nutrient cycling and maintaining the ecological health and stability of freshwater ecosystems
Spielhallen und Wettbüros: die "schwarzen Schafe" der Stadtkultur
No full textSind Spielhallen und Wettbüros die "schwarzen Schafe" der Stadtkultur? In einem kurzen historischen Abriss wird aufgezeigt, dass die Verheißung eines leistungslos erworbenen Gewinns der "Obrigkeit" immer schon ein Dorn im Auge war.
Aus der Sozialfigur des faulen Müßiggängers wurde im Verlauf der Geschichte dann der stets Suchtgefährdete und potentiell Beschaffungskriminelle.
Das Buch beleuchtet folgende weitere Themen:
- Unterschiede zwischen Spielen/Bedienen und Wetten/Zocken
- volkswirtschaftliche und betriebswirtschaftliche Daten
- Kritik zur Datenlage gefährdeter und pathologischer Spieler
- Sozialstruktur und ein kritischer Blick auf das Verständnis von "Sucht"
- Interviews mit Vertretern von Stadtverwaltungen
- anschauliche Beschreibungen zu Spielhallen und Wettbüros
- Perspektiven für den zukünftigen Umgang mit diesen Einrichtunge
Zwischen Hype und Evidenz: Generationenunterschiede bei der Arbeitgeberattraktivität
No full textIn der öffentlichen Debatte wird die Generation Z häufig als zentrale Herausforderung für die zukünftige Arbeitswelt dargestellt. Es wird behauptet, dass diese Generation, geprägt durch digitale und gesellschaftliche Umbrüche, andere Erwartungen an Arbeitgeber hat als ihre Vorgänger. Unsere Studie untersucht, ob diese Annahme wissenschaftlich haltbar ist und ob sich die Relevanz von Arbeitgeberattraktivitätsfaktoren zwischen den Generationen Baby Boomer, Generation X, Y und Z signifikant unterscheidet.
Basierend auf einem neuen empirischen Ansatz analysieren wir mit einer umfangreichen deutschen Stichprobe (N=1133) mittels multipler Regressionen die Vorhersagekraft von 19 Arbeitgeberattraktivitätsfaktoren für die allgemeine Arbeitgeberattraktivität. Dabei prüfen wir, ob und inwieweit die Generationszugehörigkeit moderierende Effekte auf die Bedeutung dieser Faktoren hat.
Die Ergebnisse zeigen, dass wesentliche Attraktivitätsfaktoren wie Identifikation mit dem Unternehmen, Management und Führung sowie die Arbeitsaufgabe generationsübergreifend relevant sind. Unterschiede zeigen sich lediglich in einzelnen Dimensionen wie Arbeitsplatzsicherheit, Corporate Social Responsibility, Work-Life-Balance und Unternehmensimage, wobei die Varianzaufklärung durch Generationsunterschiede äußerst gering ist (<2 %) und die signifikanten Regressionskoeffizienten im Durchschnitt nur bei .23 liegen.
Die Studie liefert eine empirische Basis für die Diskussion über Generationsunterschiede bei arbeitsrelevanten Einstellungen. Unsere Ergebnisse stellen die gängige Praxis von generationsspezifischem Employer Branding und eine Überschätzung von Generationsunterschieden, die auf stereotypen Annahmen beruhen, infrage. Selbst Alters- und Lebensphaseneffekte lassen sich in unseren Ergebnissen kaum nachweisen. Zukünftige Forschung sollte verstärkt longitudinale Designs verwenden, um die Dynamik von Alter, Lebensphasen und Generationen besser zu verstehen