University of Siegen
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Publication Access status: Metadata only , A novel data-based approach for monitoring fatigue crack propagation in welded joints under varying ambient temperature using the electromechanical admittanceFatigue crack growth is one of the most common damage mechanisms of structural components and can result in a sudden and unexpected abrupt fracture which can cause catastrophic failure. Thus, monitoring of crack propagation is an important topic of structural health monitoring. For that reason, this work aims at the detection of crack propagation by the application of a high-frequency vibration-based method, using the electromechanical admittance (EMA). It enables the local monitoring of the coupled dynamic behavior of the structure and the piezoelectric transducer which changes, for example, due to damage. It is the purpose of this study to develop a method from the recorded data reflecting fatigue crack growth in weld zones. As it is known that the data are affected by temperature, a temperature compensation strategy is considered. In this study, a presentation of the coupled EMA data has been found, which allows the isolation of the crack propagation effects. Within the scope of fatigue experiments, fatigue cracks were introduced into threaded bolts of rail support points, welded onto base plates. In practice, they are embedded in a layer of mortar and, therefore, have poor accessibility. Electromechanical impedance measurements were carried out at different states of fatigue crack growth. The fatigue crack growth was validated by strain gauge measurements executed during the fatigue experiment. The proposed feature was calculated from the recorded EMA data. The technique produces promising results detecting fatigue cracks and can also be transferred to similar types of welded joints or rods where fatigue crack growth occurs.Source Type:Article1 - Some of the metrics are blocked by yourconsent settings
Publication Access status: Metadata only , Analysis of the sound insulation performance of periodic wall structures by a virtual acoustic laboratoryThe propagation of acoustic waves in periodic structures, also known as phononic crystals or PCs, is prohibited in certain frequency ranges, which are referred to as the frequency band-gaps. The existence, the location and the width of the frequency band-gaps are mainly determined by the geometrical parameters and the material properties of the PCs. In this work, a virtual acoustic laboratory based on a fully coupled fluid-structure interaction (FSI) model is developed to determine the sound insulation capacity of one-dimensional (1D) and two-dimensional (2D) periodic walls. The FSI model is discretized using the frequency-domain spectral element method (FDSEM), which is an advanced finite element method (FEM) using special high-order shape functions. Following the guidelines of the ISO10140, the setup of the developed FSI model allows us to take into account the essential physical phenomena, especially the interaction of the wall structure with the fluid domains (air). The FSI model based on the FDSEM increases the computational efficiency and accuracy in comparison with the standard FEM. Several numerical examples will be presented and discussed to show that the designed periodic walls in certain frequency ranges within the band-gaps may exhibit much better sound insulation capabilities than monolithic walls.Source Type:Article3 - Some of the metrics are blocked by yourconsent settings
Publication Access status: Metadata only , Nanodentistry aspects explored towards nanostructured ZrO2: Immobilizing zirconium-oxide nanotube coatings onto zirconia ceramic implant surfacesWe report on a facile strategy to impart nanostructured morphology to commercially available ceramic-preforms used for biomedical applications in the field of dentistry. This process involves the deposition of nanotubular zirconium-oxide (ZrNT) membranes onto zirconia (ZrO2) ceramic discs at ambient conditions. ZrNTs are fabricated via electrochemical anodization of zirconium foil in a one-pot synthesis. The ZrNT film is detached from the metal-foil using office-adhesive tape and freestanding ZrNT films were obtained via dissolution of adhesives in a solvent bath, which also facilitate the transfer of ZrNT film onto the ceramic. This simple technique allows to impart a robust micro-nanoscale structure to bulk-ceramics that can potentially offer insights into designing ‘smart’ implants in the field of ceramic-biomaterial applications.Source Type:Article3 - Some of the metrics are blocked by yourconsent settings
Publication Access status: Metadata only , Counter-practices: Understanding sensor datafication through subversive action(2024); Sensors have become embedded in all kinds of environments. Their ubiquity has prompted a boom in scholarly engagement centered around the effects of digitally interconnected sensor media and the data traces they ceaselessly produce. This research generally focuses either on theoretical or philosophical macro-perspectives—approaching the topic “from above,” so to speak—or it is ethnographic, “from below,” analyzing the practices of sensory (self-)surveillance, for example in the context of the quantified self-movement. In this article, we propose a situated, praxeological approach that combines both foci: expanding on the epistemically productive concepts of glitches and breakdowns, we follow three strands of what we call “counter-practices”—hiding in plain sight, dis/simulation, and the exploitation of sensor logics—through which we explore the inherent operations of technological sensing and sensemaking. We trace these counter-practices through historic and recent contexts, considering the interrelation of bodies, media and environments, and extrapolating epistemological conclusions that are meaningful for critiquing the codes, logics, and logistics of recent sensor-media societies. Asking how certain practices elude and subvert intended processes of sensor datafication provides a methodological blueprint for media studies and cultural theory that are faced with an algorithmic and technological situation that has rendered itself largely unobservable.Source Type:Article3 - Some of the metrics are blocked by yourconsent settings
Publication Access status: Metadata only , Effects of renormalon scheme and perturbative scale choices on determinations of the strong coupling from ${e}^{+}{e}^{−}$ event shapesWe study the role of renormalon cancellation schemes and perturbative scale choices in extractions of the strong coupling constant <a:math xmlns:a="http://www.w3.org/1998/Math/MathML" display="inline"><a:msub><a:mi>α</a:mi><a:mi>s</a:mi></a:msub><a:mo stretchy="false">(</a:mo><a:msub><a:mi>m</a:mi><a:mi>Z</a:mi></a:msub><a:mo stretchy="false">)</a:mo></a:math> and the leading nonperturbative shift parameter <e:math xmlns:e="http://www.w3.org/1998/Math/MathML" display="inline"><e:msub><e:mi mathvariant="normal">Ω</e:mi><e:mn>1</e:mn></e:msub></e:math> from resummed predictions of the <h:math xmlns:h="http://www.w3.org/1998/Math/MathML" display="inline"><h:msup><h:mi>e</h:mi><h:mo>+</h:mo></h:msup><h:msup><h:mi>e</h:mi><h:mo>−</h:mo></h:msup></h:math> event shape thrust. We calculate the thrust distribution to <j:math xmlns:j="http://www.w3.org/1998/Math/MathML" display="inline"><j:mrow><j:mi mathvariant="normal">N</j:mi><j:mrow><j:mmultiscripts><j:mrow><j:mi mathvariant="normal">L</j:mi></j:mrow><j:mprescripts/><j:none/><j:mrow><j:mn>3</j:mn></j:mrow></j:mmultiscripts></j:mrow><j:msup><j:mrow><j:mi mathvariant="normal">L</j:mi></j:mrow><j:mrow><j:mo>′</j:mo></j:mrow></j:msup></j:mrow></j:math> resummed accuracy in soft-collinear effective theory (SCET) matched to the fixed-order <o:math xmlns:o="http://www.w3.org/1998/Math/MathML" display="inline"><o:mi mathvariant="script">O</o:mi><o:mo stretchy="false">(</o:mo><o:msubsup><o:mi>α</o:mi><o:mi>s</o:mi><o:mn>2</o:mn></o:msubsup><o:mo stretchy="false">)</o:mo></o:math> prediction, and perform a new high-statistics computation of the <t:math xmlns:t="http://www.w3.org/1998/Math/MathML" display="inline"><t:mi mathvariant="script">O</t:mi><t:mo stretchy="false">(</t:mo><t:msubsup><t:mi>α</t:mi><t:mi>s</t:mi><t:mn>3</t:mn></t:msubsup><t:mo stretchy="false">)</t:mo></t:math> matching in , although we do not include the latter in our final <y:math xmlns:y="http://www.w3.org/1998/Math/MathML" display="inline"><y:msub><y:mi>α</y:mi><y:mi>s</y:mi></y:msub></y:math> fits due to some observed systematics that require further investigation. We are primarily interested in testing the phenomenological impact sourced from varying amongst three renormalon cancellation schemes and two sets of perturbative scale profile choices. We then perform a global fit to available data spanning center-of-mass energies between 35–207 GeV in each scenario. Relevant subsets of our results are consistent with prior SCET-based extractions of <ab:math xmlns:ab="http://www.w3.org/1998/Math/MathML" display="inline"><ab:msub><ab:mi>α</ab:mi><ab:mi>s</ab:mi></ab:msub><ab:mo stretchy="false">(</ab:mo><ab:msub><ab:mi>m</ab:mi><ab:mi>Z</ab:mi></ab:msub><ab:mo stretchy="false">)</ab:mo></ab:math>, but we are also led to a number of novel observations. Notably, we find that the combined effect of altering the renormalon cancellation scheme and profile parameters can lead to few-percent-level impacts on the extracted values in the <eb:math xmlns:eb="http://www.w3.org/1998/Math/MathML" display="inline"><eb:msub><eb:mi>α</eb:mi><eb:mi>s</eb:mi></eb:msub><eb:mo>−</eb:mo><eb:msub><eb:mi mathvariant="normal">Ω</eb:mi><eb:mn>1</eb:mn></eb:msub></eb:math> plane, indicating a potentially important systematic theory uncertainty that should be accounted for. We also observe that fits performed over windows dominated by dijet events are typically of a higher quality than those that extend into the far tails of the distributions, possibly motivating future fits focused more heavily in this region. Finally, we discuss how different estimates of the three-loop soft matching coefficient <hb:math xmlns:hb="http://www.w3.org/1998/Math/MathML" display="inline"><hb:msubsup><hb:mi>c</hb:mi><hb:mover accent="true"><hb:mi>S</hb:mi><hb:mo stretchy="false">˜</hb:mo></hb:mover><hb:mn>3</hb:mn></hb:msubsup></hb:math> can also lead to measurable changes in the fitted <lb:math xmlns:lb="http://www.w3.org/1998/Math/MathML" display="inline"><lb:mo stretchy="false">{</lb:mo><lb:msub><lb:mi>α</lb:mi><lb:mi>s</lb:mi></lb:msub><lb:mo>,</lb:mo><lb:msub><lb:mi mathvariant="normal">Ω</lb:mi><lb:mn>1</lb:mn></lb:msub><lb:mo stretchy="false">}</lb:mo></lb:math> values. Published by the American Physical Society 2024Source Type:Article1 - Some of the metrics are blocked by yourconsent settings
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Publication Access status: Metadata only , 3
