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A fix that may fail : a qualitative model to explore potential rebound effects of digital textile microfactories
No full textFast fashion principles and mass production within globalised supply chains are pivotal in driving the economic success of the fashion industry, but they also contribute significantly to its severe environmental impacts, which must be mitigated. Digital textile microfactories are innovative small‐scale fully digitalised design and manufacturing systems that present a promising technological solution. These offer the companies that adopt them environmental and economic advantages. However, their widespread adoption in the industry may have unintended consequences. This study hypothesises a rebound effect within the industry and proposes a qualitative modelling approach based on causal loop diagrams. We present a model for identifying rebound mechanisms that may accelerate purchases, along with a mitigation strategy emphasising the consideration of customer behaviour. The contribution of this paper is twofold: Firstly, it provides a starting point for detailed quantitative studies, and secondly, it offers insights for policy‐making towards a sustainable transition in the industry
Analyse und Bewertung von Leichtbaupotenzial
No full textLeichtbau wird als Konstruktionstechnik für die Erreichung verschiedenster Ziele eingesetzt, die sich in die Felder Ökologie, Ökonomie und Technik einteilen lassen. Der erbrachte Nutzen des Leichtbaus sowie der zu investierende Aufwand für den Einsatz muss sich an diesen Zielen messen lassen. Die Ziele lassen sich in sogenannte Leichtbaumotivatoren übersetzen, die im Rahmen von Analysen dazu verwendet werden, Leichtbaupotenzial abzuleiten. Dieses Potenzial gibt einen Hinweis darauf, an welcher Stelle im Produkt Leichtbau den größten Nutzen erbringt. Eine Untersuchung des Stands der Technik und Forschung hat offengelegt, dass bestehende Methoden zum Ableiten von Leichtbaupotenzial unflexibel gegenüber verschiedenen Zusammensetzungen von Leichtbaumotivatoren sind und somit fallspezifisch ungenaue oder teilweise falsche Ergebnisse ausweisen. Des Weiteren zeigen die Untersuchungen die Eindimensionalität bei der Betrachtung von Produktmasse im Leichtbaukontext. Werden die Motivatoren und damit die Ziele des Leichtbaueinsatzes als Grundlage herangezogen, ist eine Zielerreichung teilweise neben einer reinen Reduzierung auch durch eine Umverteilung von Produktmasse erreichbar. Dieser mehrdimensionale Blickwinkel auf verschiedene Optionen des Produktentwicklers, Leichtbauziele zu erreichen, wird in der Analyse von Leicht-baupotenzial bisher nicht berücksichtigt.
Den beschriebenen Defiziten begegnet die vorliegende Arbeit. Das übergeordnete Ziel ist es, dem Produktentwickler eine Methodik bereitzustellen, mit dem in frühen Entwicklungsphasen eine Aussage über das Leichtbaupotenzial von Produktkomponenten sowie eine Entscheidung für die Umsetzung bestimmter Leichtbaukonzepte getroffen werden kann. Hierbei sollen Massenreduktion und Massenumverteilung gleichermaßen Berücksichtigung finden. Die Anwendung dieser Unterstützung hat zum Ziel, die Effizienz und die Effektivität von Leichtbaukonzepten zu vergrößern. Damit soll ein Beitrag zur Leichtbauproduktentwicklung im Allgemeinen und zur Leichtbaupotenzialanalyse im Speziellen geleistet werden. Die im Rahmen der Arbeit entwickelte Methodik zur Analyse und Bewertung von Leichtbaupotenzial setzt dazu vier unterstützende Bausteine ein, die teilweise konsekutiv oder parallel durchgeführt werden. Im ersten Schritt werden durch eine Analyse der Situation inklusive aller Stakeholder die Leichtbaumotivatoren abgeleitet und zusammengetragen. Hierfür wird sowohl ein Vorgehen als auch eine Motivatorensammlung mit gegenseitigen Abhängigkeiten zur Verfügung gestellt. Der nächste Bau-stein ist eine Methode zur Analyse der Massenreduktionspotenziale. Aufbauend auf einem vereinheitlichenden Abstraktionslevel können beliebige Motivatoren kombiniert und ein Leichtbaunutzen errechnet werden, der dem Massenreduktionspotenzial entspricht. Parallel sieht die Methodik einen Baustein zur Analyse von Massenumverteilungspotenzialen vor. Mittels einer Design Structure Matrix werden verschiedene durch Massenumverteilung beeinflussbare Motivatoren durch Abhängigkeiten zwischen Komponenten interpretiert und die Abhängigkeiten bewertet. Ein Clusteralgorithmus bildet Module, die Hinweise auf zweckmäßige Umverteilungen von Komponentenmasse geben. Nach einer, in dieser Arbeit nicht unterstützten, ersten Konzeptualisierung von Leichtbaulösungen, die auf den Analyseergebnissen aufbauen, ermöglicht der letzte Methodikbaustein eine Bewertung der unterschiedlichen Konzepte durch die Ableitung von Aufwands- und Risikokennzahlen. Final wird der Produktentwickler so zu einem Kosten-Nutzen-Vergleich befähigt und kann eine systematische Entscheidung für oder gegen eine Massenreduzierung oder Massenumverteilung hinsichtlich neuer Konzeptlösungen treffen.
Die gesamte Methodik sowie einzelne Methodikbausteine wurden im Rahmen von fünf Industriekooperationen evaluiert. In zwei studentischen Praktikumsversuchen konnten zudem beide Potenzialanalysebausteine evaluiert werden. Die Ergebnisse weisen eine signifikante Unterstützung bezüglich der Anwendung aus. Hinsichtlich des Erfolgs wurden initiale Evaluationsaktivitäten durchgeführt. Der übergeordnete, langfristige Erfolg, der erst mit der Implementierung sowie der wiederholten Anwendung in den Unternehmen hervortritt, konnte im Zuge dieser Arbeit nicht geleistet werden. Des Weiteren ist die Methodik hinsichtlich ihrer Flexibilität in verschiedenen Branchen und Produktkontexten weiter zu evaluieren. Dennoch konnte ein konkreter Erfolg beider Potenzialanalysebau-steine in zwei Projekten mit zwei Industriepartnern nachgewiesen werden, da hier ein angepasster Entwurf entwickelt bzw. ein erster Prototyp gefertigt wurde. Beide angepassten Produkte wurden nach Aussage der Befragten maßgeblich durch die angewandten Unterstützungen beeinflusst.
Initial ist somit gezeigt worden, wie Produktentwickler die Abhängigkeiten von Massenreduktion und Massenumverteilung im Hinblick auf ihre Leichtbauziele ausnutzen können und dadurch in der Lage sind, Leichtbaupotenzial zu analysieren und es zu bewerten
A comparison of lower body gait kinematics and kinetics between Theia3D markerless and marker-based models in healthy subjects and clinical patients
No full textThree-dimensional (3D) marker-based motion capture is the current gold standard to assess and monitor pathological gait in a clinical setting. However, 3D markerless motion capture based on pose estimation is advancing into the field of gait analysis. This study aims at evaluating the lower-body 3D gait kinematics and kinetics from synchronously recorded Theia3D markerless and CAST marker-based systems. Twelve healthy individuals and 34 clinical patients aged 8-61 years walked at self-selected speed over a 13 m long walkway. Similarity between models was statistically analysed using inter-trial variability, root mean square error, Pearson’s correlation coefficient and Statistical Parametric Mapping. Inter-trial variability was on average higher for clinical patients in both models. Overall, the markerless system demonstrated similar gait patterns although hip and knee rotations were non-comparable. Pelvic anterior tilt was significantly underestimated. Significant differences especially in peak values at specific phases of the gait cycle were observed across all planes for all joints (more so for clinical patients than healthy subjects) as well as in the sagittal powers of the hip, knee and ankle. Theia3D markerless system offers great potential in gait analysis. This study brings awareness to potential clinical users and researchers where they can have confidence, as well as areas where caution should be exercised.Projekt DEALUniversität Stuttgar
Pressure-temperature-time evolution of a polymetamorphic paragneiss with pseudomorphs after jadeite from the HP-UHP gneiss‐eclogite unit of the Variscan Erzgebirge crystalline complex, Germany
No full textA quartz‐rich paragneiss from the Variscan Erzgebirge Crystalline Complex (ECC) was studied in detail because of abundant millimetre‐sized and clearly oriented pseudomorphs after a sodic mineral interpreted to have been jadeite. This mineral, or pseudomorphs after it, is rarely found in extensive high‐pressure (HP)-ultrahigh‐pressure (UHP) terranes worldwide despite reported pressure-temperature (P-T) conditions suitable for the formation of jadeite in common paragneisses and orthogneisses. In the studied rock, which contains abundant large and oriented potassic white mica flakes and minor millimetre‐sized garnet grains, the pseudomorphs consist of clusters of small albite grains with thin phengitic muscovite flakes in between. X‐ray maps for Ca and Mg in garnet demonstrate that an early generation of this mineral (Gt1) was corroded and subsequently overgrown by a Ca‐richer generation (Gt2). White mica is phengite with maximum Si contents of 3.42 atoms per formula unit. P-T conditions of 0.85 GPa and 650°C and 1.7 GPa and 660°C were derived for the formation of Gt1 and Gt2 rim + Si‐rich phengite, respectively, using pseudosection modelling. The latter conditions representing the pressure peak experienced by the paragneiss are compatible with the original presence of jadeite and possibly paragonite as well. This metamorphic peak occurred at 338.4 ± 2.3 (2σ) Ma based on in situ dating of monazite grains with the electron microprobe. A single monazite age of 386.4 ± 10.5 (2σ) Ma is related to the formation of Gt1. Thus, a Late Devonian metamorphism is suggested here for the first time to have occurred in ECC gneisses before the major HP event in the Early Carboniferous. Furthermore, the study demonstrates that the eclogite‐facies gneisses of the Gneiss‐Eclogite Unit of the ECC experienced peak pressures of not more than 2 GPa in contrast to recent proposals of an extensive UHP area in this unit. In addition, it is suggested that the localized occurrence of UHP rocks surrounded by other lithologies otherwise lacking evidence for UHP conditions should be interpreted with caution with respect to their regional extent and significance.National Natural Science Foundation of Chin
Investigation of inert gas washout methods in a new numerical model based on an electrical analogy
No full textAbstractInert gas washout methods have been shown to detect pathological changes in the small airways that occur in the early stages of obstructive lung diseases such as asthma and COPD. Numerical lung models support the analysis of characteristic washout curves, but are limited in their ability to simulate the complexity of lung anatomy over an appropriate time period. Therefore, the interpretation of patient-specific washout data remains a challenge. A new numerical lung model is presented in which electrical components describe the anatomical and physiological characteristics of the lung as well as gas-specific properties. To verify that the model is able to reproduce characteristic washout curves, the phase 3 slopes (S3) of helium washouts are simulated using simple asymmetric lung anatomies consisting of two parallel connected lung units with volume ratios of 1.250.75, 1.500.50, and 1.750.25 and a total volume flow of 250 ml/s which are evaluated for asymmetries in both the convection- and diffusion-dominated zone of the lung. The results show that the model is able to reproduce the S3 for helium and thus the processes underlying the washout methods, so that electrical components can be used to model these methods. This approach could form the basis of a hardware-based real-time simulator.Graphical abstractProjekt DEALUniversität Stuttgar
Test rig for validating the integrated motion measurement of flexible beams
No full textThe fundamental principle of integrated motion measurement (IMM) is integrated navigation with inertial sensors combined with, for example, a satellite navigation receiver. Accordingly, IMM makes use of the specific advantages of complementary sensors and blends them in a filter algorithm. To meet requirements in advanced motion measurements, for instance, for structural health monitoring or for structural control purposes, the approach of a single rigid body like in classical navigation no longer holds for IMM. As a solution, additional degrees of freedom (DOFs) for the moving structure are introduced, which represent deformations and allow the navigated body to be treated as a flexible structure. To cover a variety of flexible deformation shapes, a sufficient number of distributed inertial sensors is required. To restrict accumulating errors of these sensors, additional structural measurements for aiding are necessary. The signals of the inertial sensors and the aiding measurements are fused by an extended Kalman filter (EKF) to obtain an optimal estimation of the usual navigation states, extended by the deformation variables. The contribution presents the preparation of the experimental validation of an IMM system for a flexible structure, which represents an idealization of a wing or rotor blade by a movable beam. The mechanical and electrical setup of a test rig is described. Furthermore, the simulation of the test configuration, that is the model of a test beam with a variety of distributed sensors for generating artificial measurements as a test reference, is discussed. Finally, for an optimal sensor placement, the two methods of effective independence and maximization of modal energy are compared and experimentally tested for different amounts of additional flexible DOFs.Projekt DEA
Secure cryptographic hardware : assessing logic-locking and fault attack vulnerabilities
No full textThe protection of hardware implementations of cryptographic primitives against physical attacks and supply-chain threats remains a critical challenge. This thesis investigates the fault attack vulnerabilities and the secure composability of various countermeasures, with a particular focus on logic-locking - a widely adopted design-for-trust technique aimed at safeguarding against intellectual property piracy and overproduction.
One of the primary objectives of this work is to explore whether protecting a circuit against one threat inadvertently makes it more vulnerable to another, particularly when logic locking is applied to cryptographic circuits. Two novel attacks that exploit the presence of logic-locking circuitry are introduced as a major contribution of this thesis. Logic-locking typically serves to protect circuits by allowing them to function only when the correct locking key is provided. However, it is demonstrated that the ability to unlock the circuit incorrectly can provide adversaries with new and effective attack vectors. The first attack, Locking Enabled Differential Fault Analysis (LEDFA), is shown to make incorrectly unlocked circuits more susceptible to fault attacks due to the introduction of new propagation paths by the logic-locking circuitry. Experimental evaluations across various ciphers and logic-locking schemes revealed that fault attacks become either possible or consistently easier in the presence of incorrect unlocking. Moreover, it was found that logic-locking can, in some cases, make circuits vulnerable to classical algebraic attacks without the need for any fault injection, a case referred to as Locking Enabled Differential Analysis (LEDA). This vulnerability results in a significant reduction in the cryptographic strength. The success factors behind LEDA are thoroughly investigated, leading to the proposal of a countermeasure designed to enhance the resilience of logic-locked cryptographic circuits.
This countermeasure involves restricting cryptographic key bits from being directly integrated into locking subcircuits, thereby mitigating the vulnerabilities facilitating LEDA. Additionally, a Test Vector Leakage Assessment (TVLA) of incorrectly unlocked AES implementation is discussed, highlighting that logic-locking significantly influences side-channel leakage. These findings raise concerns regarding the use of logic-locking in cryptographic circuits, suggesting that it, in fact, compromises rather than enhances security.
The second major contribution of this thesis is the development of a methodology for evaluating the vulnerability of cryptographic circuits to fault injection attacks facilitated by clock manipulation. It is well recognized that state-of-the-art fault attacks typically require either a large number of low-precision fault injections (statistical attacks) or very few injections using sophisticated equipment (algebraic attacks) to breach modern cryptosystems. For instance, a well-known fault attack on AES-128 requires only a single fault injection, provided that the fault effects are confined to a specific 8-bit nibble of the state. This research aimed to optimize the probability of achieving the desired faulty state bit patterns during low-cost clock manipulation, thereby combining the advantages of both statistical and algebraic attacks. For this purpose, a comprehensive methodology is developed, which involves extending formal Boolean satisfiability (SAT) models initially designed for waveform-accurate automatic test pattern generation (ATPG) procedures to fault attacks on cryptographic hardware. A distinguishing feature of this analysis is the presence of fixed-yet-unknown secret cryptographic bits that influence the faulty state bit patterns. A model-counting (MC) approach is utilized to calculate the probability of success across different secret cryptographic bit combinations using a novel Vulnerability Index (VI). This methodology provides a robust framework for assessing the susceptibility of cryptographic circuits to such fault injection attacks. The practical implications of these findings are significant for both cryptographic hardware designers and security analysts. A structured approach is offered for security analysts to evaluate and strengthen cryptographic systems against fault injection attacks, ensuring a comprehensive defense strategy
Digital twin and the asset administration shell : an analysis of the three types of AASs and their feasibility for digital twin engineering
No full textEngineering digital twins is a software and systems engineering challenge for which no systematic approach exists. The Asset Administration Shell is becoming a popular foundation for digital twins in Industry 4.0 and it comes in different types that support the engineering of different kinds and parts of digital twins. We investigate how it supports realizing common requirements for digital twins. To this end, we investigate how each of the three Asset Administration Shell types can contribute to the systematic engineering of specific components of digital twins. Therefore, we analyzed popular definitions and conceptual models of digital twins and extracted requirements that at least two of them share. We compare the resulting requirements with Asset Administration Shells of different types and conclude with open challenges in the implementation of digital twins with this technology. This supports practitioners and researchers in identifying the most suitable type of Asset Administration Shell for their specific digital twin engineering needs and identifies gaps worthy of future research toward a systematic engineering of digital twins.Projekt DEALDeutsche Forschungsgemeinschaf
Ermittlung konsistenter Verkehrsstärken für die Bemessung von Straßenverkehrsanlagen
No full textDie Arbeit stellt ein Verfahren zur Ermittlung konsistenter Verkehrsstärken vor, motiviert durch die Bemessung an Straßenverkehrsanlagen. Dabei werden die zeitliche und räumliche Datenaufbereitung mit einer Matrixschätzung kombiniert. Ein zentrales Element ist die Klassifizierung der Zählstellen bezüglich der Messwertzuverlässigkeit. Anhand dieser Klassifizierung werden Toleranzen bei der Matrixschätzung iterativ angepasst und fehlerhafte Zähldaten identifiziert. Zudem wird der Einfluss der Matrixschätzung bei unterschiedlichen Anwendungsfällen untersucht. Das Verfahren wurde an 90 Autobahnknoten getestet. Zusätzlich wurden für sieben Knotenpunkte auf Autobahnen Gewichtungsmatrizen aus verschiedenen Datenquellen abgeleitet. Damit wird analysiert, inwiefern sich die Verkehrsstärken für unterschiedliche Szenarien der Datenverfügbarkeit rekonstruieren lassen und wie sich dies auf die Bemessung auswirkt
Impact of the sulfurized polyacrylonitrile cathode microstructure on the electrochemical performance of lithium-sulfur batteries
No full textThe growing demand for advanced energy storage systems requires the development of next‐generation battery technologies with superior energy density and cycle stability, with lithium-sulfur (Li-S) batteries representing a promising solution. Sulfur‐containing polyacrylonitrile cathodes (SPAN) for Li-S batteries are a significant advancement for this next‐generation battery chemistry, addressing the major issue of limited cycle life encountered in conventional carbon/sulfur composite cathodes. In the presented study, the influence of available ionic and electronic conduction pathways within the cathode on the electrochemical performance of SPAN‐based Li-S batteries is studied in details. To this end, a series of SPAN cathodes with different microstructures is prepared by adapting the compression degree of calendering. Mechanical and morphological characterizations confirm a pronounced springback effect due to a characteristic elastic deformation behavior of SPAN. Electrochemical impedance spectroscopy (EIS) shows increased cathode impedance values with multiple overlapping processes in the high‐ to mid‐frequency region in highly compressed SPAN cathodes. Moreover, while the (first) discharge capacity is unaffected, the subsequent charge capacity decreases substantially for highly compressed cathodes. The electrochemical experiments and electrochemical continuum simulations confirm that this phenomenon is mainly due to the disturbance of the electronic percolation pathways caused by the springback behavior during calendering.Projekt DEA