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The KIT Calculation Platform for Improving the Reliability of the Analysis of the Radiological Consequences of Hypothetical Severe Accidents in Water-Cooled Nuclear Power Plants
No full textSimilar stretch reflexes and behavioral patterns are expressed by the dominant and nondominant arms during postural control
No full textLimb dominance is evident in many daily activities, leading to the prominent idea that each hemisphere of the brain specializes in controlling different aspects of movement. Past studies suggest that the dominant arm is primarily controlled via an internal model of limb dynamics that enables the nervous system to produce efficient movements. In contrast, the nondominant arm may be primarily controlled via impedance mechanisms that rely on the strong modulation of sensory feedback from individual joints to control limb posture. We tested whether such differences are evident in behavioral responses and stretch reflexes following sudden displacement of the arm during posture control. Experiment 1 applied specific combinations of elbow-shoulder torque perturbations (the same for all participants). Peak joint displacements, return times, end point accuracy, and the directional tuning and amplitude of stretch reflexes in nearly all muscles were not statistically different between the two arms. Experiment 2 induced specific combinations of joint motion (the same for all participants). Again, peak joint displacements, return times, end point accuracy, and the directional tuning and amplitude of stretch reflexes in nearly all muscles did not differ statistically when countering the imposed loads with each arm. Moderate to strong correlations were found between stretch reflexes and behavioral responses to the perturbations with the two arms across both experiments. Collectively, the results do not support the idea that the dominant arm specializes in exploiting internal models and the nondominant arm in impedance control by increasing reflex gains to counter sudden loads imposed on the arms during posture control.
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A prominent hypothesis is that the nervous system controls the dominant arm through predictive internal models and the nondominant arm through impedance mechanisms. We tested whether stretch reflexes of muscles in the two arms also display such specialization during posture control. Nearly all behavioral responses and stretch reflexes did not differ statistically but were strongly correlated between the arms. The results indicate individual signatures of feedback control that are common for the two arms
The effects of a 9-week hip focused weight training program on hip and knee kinematics and kinetics in experienced female dancers
No full textIncreased involvement of the hip musculature during some movements is associated with enhanced performance and reduced injury risk. However, the impact of hip dominant weight training methods on movement strategy has seen limited attention within the literature. The aim of this study was to evaluate if a 9-week hip dominant weight training intervention promotes a more hip dominant movement strategy leading to an improvement in countermovement jump performance. Twenty-two experienced female dancers were recruited and separated into an intervention (age 24.4 ± 6.3 years, body height 165.5 ± 5.8 cm, body mass 65.9 ± 5.6 kg) and a control (age 22.9 ± 5.6 years, body height 163.3 ± 5.4 cm, body mass 57.4 ± 6.8 kg) group. The intervention group participated in a 9-week hip dominant training intervention, which consisted of a wide stance back squat, Romanian deadlift, hip thrusters, and a bent over row. Hip and knee kinematics and kinetics, and countermovement jump performance were assessed pre and post training. Significant interaction effects were found for peak hip joint moment (p = 0.030, η2 = 0.214) and countermovement jump performance (p = 0.003, η2 = 0.356), indicating an increase in peak hip joint moment and countermovement jump performance for the intervention group. Specifically, the intervention group showed a mean increase in jump height of 11.5%. The data show that the use of a hip dominant weight training strategy can improve hip contribution in the propulsion phase of the countermovement jump. Strength and conditioning specialists should incorporate hip dominant weight training exercises to increase hip strength and improve performance
Integration von Zuverlässigkeit der Reisezeit in ein makroskopisches Verkehrsnachfragemodell
No full textFunktionierende Verkehrssysteme sind für die Alltagsmobilität unverzichtbar, verursachen jedoch erhebliche Umwelt- und Gesundheitsbelastungen. Eine wirksame Reduktion dieser Risiken erfordert die Verlagerung vom motorisierten Individualverkehr zum öffentlichen Verkehr. Voraussetzung dafür ist ein zuverlässiges OV-Angebot – ein Aspekt, der in Verkehrsnachfragemodellen bislang selten explizit berücksichtigt wird. Diese Masterarbeit quantifiziert den Einfluss der Reisezeitzuverlässigkeit auf die Verkehrsmittelwahl mithilfe des makroskopischen Verkehrsnachfragemodells des Verbands Region Stuttgart. Hierzu werden Verspätungskennwerte des schienengebundenen Regionalverkehrs berechnet und in der Verkehrsmittelwahl des Modells durch eine Anpassung der Nutzenfunktion berücksichtigt. Drei Szenarien mit unterschiedlicher Sensitivität der Bewertung der Reisezeitvariabilität bilden die Wirkungen räumlich ab und ermöglichen die Ableitung von Fahrgastgewinnen.
Die Ergebnisse verbesserter Zuverlässigkeit zeigen deutliche Nachfragezuwachse insbesondere auf nachfragestarken und stark verspäteten Relationen (u.a. Stuttgart–Esslingen, Göppingen Mittelzentrum–Göppingen Verflechtungsbereich und entlang des Korridors Bietigheim-Bissingen–Esslingen), während Relationen mit geringen Verspätungen geringere Effekte aufweisen. Zudem verlängern sich die OV-Wegelangen. Methodisch begrenzend wirkt, dass Verspätungen nur für einen Teil der Wege vorlagen und als statische Werte ohne Berücksichtigung von Umstiegszeiten in die Umlegung eingingen. Die Integration von pauschalen Verspätungswerten für Wege ohne Verspätungswerte vergrößern die Nachfragezuwachse, sind jedoch vorsichtig zu interpretieren. Insgesamt zeigt die Arbeit, dass die Integration der Reisezeitzuverlässigkeit – trotz erheblicher Daten- und Prozessaufwande – verhaltensrelevante Effekte belastbar abbildet und damit sowohl die Modellentwicklung als auch Nutzen-Kosten-Untersuchungen substantiell ergänzt. Perspektivisch sind eine Vereinfachung des Verfahrens, die Harmonisierung und Standardisierung der Verspätungsdaten sowie eine weitergehende Untersuchung verhaltensbezogener Strategien im Umgang mit Unzuverlässigkeit im öffentlichen Verkehr erforderlich
Multidimensional Stochastic Petri Nets: A Novel Approach to Modeling and Simulation of Stochastic Discrete-Event Systems
No full textProcess Mining (PM) has been proven valuable for extracting process flows from data, also in the form of stochastic Petri net (SPN) models of systems. SPNs are widely recognized for their ability to model complex, stochastic systems and are extensively used in combination with PM. While SPNs provide an intuitive and straightforward way to model complex systems, representing changes across multiple dimensions, such as energy and waste, remains challenging in their standard frameworks. In this paper, we introduce an extension of stochastic Petri nets, termed Multidimensional SPNs (MDSPNs), by extending the SPN framework to capture dynamics along different dimensions. MDSPNs facilitate a comprehensive modeling of systems’ behaviors from multiple perspectives, which can correspond to the diverse objectives of systems. To facilitate design and simulation of MDSPNs, we designed and developed MDPySPN, a Python library, which we also introduce in this paper. MDPySPN enables the simulation of MDSPNs by supporting alterations of multiple values at system events. With MDPySPN, we aim to provide researchers, engineers, and simulation professionals with a practical and extensible toolkit to model, simulate, and analyze MDSPNs, thereby supporting multi-objective optimization of stochastic processes in systems. Through a case study, we demonstrate the capabilities of modeling and simulation of MDSPNs using MDPySPN
Synthesis and Characterization of Hierarchical Structured Polyanionic Electrode Materials for Potassium-Ion-Batteries (PIBs)
No full textIm Rahmen dieser Dissertation werden sowohl die Synthese, als auch die Mikrostruktur und elektrochemische Performanz verschiedener hierarchisch strukturierter polyanionischer Elektrodenmaterialien für Kalium-Ionen-Batterien (PIBs) untersucht. Die Kombination von Sprühtrocknung und Festkörpersynthese erzeugte mikrometergroße, offenporige Granulate basierend auf nanokristallinen Primärpartikeln. Die erzeugten hierarchischen Kompositstrukturen ermöglichten eine optimierte elektrochemische Nutzung der Materialien durch eine Verbesserung der elektronischen Leitfähigkeit und Reaktionskinetik.
In Kapitel 6 wurden Kalium-Vanadium-Phosphat-Komposite (K3V2(PO4)3/C → KVP/C, KVOPO4/C → KVPO/C) als Hochvolt-Kathodenmaterialien untersucht. Die systematische Variation von Kohlenstoffquellengehalt und Sintertemperatur führte zu einer verbesserten Zyklierbarkeit und erhöhten Leitfähigkeit durch die optimierten Mikrostrukturen für einen moderaten Kohlenstoffquellengehalt und eine Sinterung bei 750 °C – 800 °C der KVP/C Komposite. Die Anpassung des Syntheseprozess für KVPO/C-Komposite führte zu einer Verbesserung der elektrochemischen Performanz um 30 % bzw. 24 % hinsichtlich Kapazität respektive Energiedichte gegenüber der Literatur.
Kapitel 7 beschreibt die Entwicklung von Kalium-Titanium-Phosphat-Kompositen (KTi2(PO4)3/C → KTP/C, KTiOPO4/C → KTPO/C) als Referenz- und Diagnostikelektroden. Die Ti-basierten Komposite zeigen ein stabiles Redoxverhalten im Bereich 1.0 V – 1.6 V vs. K⁺/K und weisen im Fall des KTP/C eine geringe Selbstentladung, sowie niedrige Polarisation von nur 50 mV bei C/20 für KTPO/C auf. Ihr Einsatz ermöglicht präzisere elektrochemische Charakterisierungen ohne die störenden, parasitären Nebeneffekte durch metallisches Kalium als Gegenelektroden in Halbzellen. Durch die Nutzung von KTP/C als Referenzelektrode konnte der große störende Einfluss auf die elektrochemische Charakterisierung in konventionellen Halbzellsetups nachgewiesen werden, wodurch die elektrochemische Performanz von KVP/C und KVPO/C unterschätzt wurde.
Kapitel 8 untersucht den Übergang von Halbzell- zu Vollzellsetups unter Verwendung der KTPO/C Diagnostikelektrode. Die resultierenden Vollzellen zeigten eine verbesserte Entladekapazität und C-Raten-Performanz bis C/2 sowie eine erhöhte Stabilität über mehrere Zyklen basierend auf einem minimierten Spannungsoffset gegenüber der Halbzellen.
Zusammenfassend wurde gezeigt, dass die hierarchische Mikrostrukturierung von Aktivmaterialien und die Nutzung stabiler Referenzelektrodensysteme entscheidend zur Verbesserung der elektrochemischen Performanz und präzisen und verlässlichen Charakterisierung von polyanionischen Aktivmaterialien in PIBs beitragen kann
FloKi: Efficient Network-Wide Flooding
No full textWe introduce FLOKI, an efficient and scalable approach for network-wide flooding in the network’s control plane. FLOKI floods packets in a structured way along replication trees installed in the forwarding plane based on the routing architecture KIRA. Compared to traditional hop-by-hop flooding, this significantly reduces control plane processing overhead. In dense topologies, it also substantially reduces network load and flooding time
A Trade-off worth making: internet fragmentation and digital sovereignty
No full textOpponents of digital sovereignty characterize the methods to achieve it as authoritarian, protectionist, and anti-innovation – ultimately leading to digital fragmentation. Digital fragmentation, roughly, is the idea that “the internet is in some danger of splintering into loosely coupled islands of connectivity.” The internet is built on, so the argument goes, the foundation of open accessibility, free movement of data and interoperability. The exercise of digital sovereignty, it is claimed, chips away at this foundation – and threatens to fragment the internet as we know it. The argument against digital sovereignty is largely premised on an assumption that is in no way obviously true: the way the internet is benefits individuals. The current functioning of internet services requires consumers to give up large amounts of sensitive personal information that are used to generate targeted advertisements. These targeted advertisements have been associated with election tampering as well as a driving force in the dissemination of conspiracy theories leading to genocide, an armed insurrection, and making it much more difficult to get the world vaccinated. Opponents of digital sovereignty may be correct in their analysis that, in the current context, methods to achieve it will cause the internet to somewhat fragment. However, too often these opponents seem to defend a status quo that is fundamentally broken and dominated by a few companies which have time and again abused their power. Until the world agrees upon rules which protect privacy and ensure the functioning of democracy, the states must accept the trade of a fragmented internet for the protection of their citizens
Confinement−Adsorption Synergy in Hybrid Carbon‐Coated Separator Enables Stable High‐Rate Quinone Cathode for Magnesium Batteries
No full textOrganic cathodes offer great promise for rechargeable magnesium batteries (RMBs) owing to their structural tunability and fast Mg transport, yet their dissolution in ether-based electrolytes leads to rapid capacity fading and poor rate performance. Herein, we design a high-performance sulfur-containing heterocyclic quinone cathode, benzo[b]naphtho[2′,3′:5,6][1,4]dithiino[2,3-i]thianthrene-5,7,9,14,16,18-hexone (BNDTH), coupled with a functional carbon-coated separator composed of graphene oxide (GO) and carboxylated multi-walled carbon nanotubes (MWCNTs−COOH) at an optimized 1:9 mass ratio. In this architecture, GO provides physical confinement to suppress BNDTH diffusion, while MWCNTs−COOH offer abundant chemical adsorption sites to immobilize soluble species. This synergistic confinement–adsorption mechanism effectively mitigates active-material loss and promotes charge transfer. As a result, the Mg//BNDTH cell exhibits significantly improved rate capability, delivering cathode capacities rising from 153 to 261 mAh g at 1 C and from 26 to 100 mAh g at 10 C over 500 cycles, along with cell-level power and energy densities of 4517 W kg and 222 Wh kg, respectively—surpassing most reported RMBs employing organic cathodes. This work presents a viable separator-engineering strategy for achieving stable and high-rate operation of soluble organic cathodes in RMBs
Compact Superconducting High-Field Magnets for NMR Applications
No full textTo increase the signal-to-noise ratio in NMR spectroscopy, strong magnetic fields are necessary along with high temporal and spatial homogeneity down to ppb levels for high resolution and sufficient chemical shift range. Currently, low temperature superconductors are used to produce very high magnetic fields but there are still challenges of compactness and portability, which our project aims to solve. Here, we will discuss on how we plan to reduce the size of the magnets by using high-temperature superconducting materials while keeping the magnetic field significantly high, at around 10 T, and sufficiently homogeneous to overcome the limitations of current bench-top NMR spectrometers that are restricted to 3 T and have lower polarisation and chemical shift. We will discuss on the various challenges we face starting from the conceptualisation, the materials, the magnet design, cryogenics, and the solutions that we have in mind including future prospect of in-house production and manufacturing, to achieve our vision of a portable, mobile high-field NMR spectrometer, that is cryogen- free and has greater accessibility