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Physical unclonable functions (PUFs) are increasingly generating attention in the field of hardware-based security for the Internet of Things (IoT). A PUF, as its name implies, is a physical element with a special and unique inherent characteristic and can act as the security anchor for authentication and cryptographic applications. Keeping in mind that the PUF outputs are prone to change in the presence of noise and environmental variations, it is critical to derive reliable keys from the PUF and to use the maximum entropy at the same time. In this work, the PUF output positioning (POP) method is proposed, which is a novel method for grouping the PUF outputs in order to maximize the extracted entropy. To achieve this, an offset data is introduced as helper data, which is used to relax the constraints considered for the grouping of PUF outputs, and deriving more entropy, while reducing the secret key error bits. To implement the method, the key enrollment and key generation algorithms are presented. Based on a theoretical analysis of the achieved entropy, it is proven that POP can maximize the achieved entropy, while respecting the constraints induced to guarantee the reliability of the secret key. Moreover, a detailed security analysis is presented, which shows the resilience of the method against cyber-security attacks. The findings of this work are evaluated by applying the method on a hybrid printed PUF, where it can be practically shown that the proposed method outperforms other existing group-based PUF key generation methods.
Analysing and predicting the advance rate of a tunnel boring machine (TBM) in hard rock is integral to tunnelling project planning and execution. It has been applied in the industry for several decades with varying success. Most prediction models are based on or designed for large-diameter TBMs, and much research has been conducted on related tunnelling projects. However, only a few models incorporate information from projects with an outer diameter smaller than 5 m and no penetration prediction model for pipe jacking machines exists to date. In contrast to large TBMs, small-diameter TBMs and their projects have been considered little in research. In general, they are characterised by distinctive features, including insufficient geotechnical information, sometimes rather short drive lengths, special machine designs and partially concurring lining methods like pipe jacking and segment lining. A database which covers most of the parameters mentioned above has been compiled to investigate the performance of small-diameter TBMs in hard rock. In order to provide sufficient geological and technical variance, this database contains 37 projects with 70 geotechnically homogeneous areas. Besides the technical parameters, important geotechnical data like lithological information, unconfined compressive strength, tensile strength and point load index is included and evaluated. The analysis shows that segment lining TBMs have considerably higher penetration rates in similar geological and technical settings mostly due to their design parameters. Different methodologies for predicting TBM penetration, including state-of-the-art models from the literature as well as newly derived regression and machine learning models, are discussed and deployed for backward modelling of the projects contained in the database. New ranges of application for small-diameter tunnelling in several industry-standard penetration models are presented, and new approaches for the penetration prediction of pipe jacking machines in hard rock are proposed.
Im Beitrag wird ein zweistufiges Verfahren für den Entwurf eines Störgrößenbeobachters für lineare, zeitinvariante Systeme vorgestellt. Hierbei wird davon ausgegangen, dass die Beobachterrückführung für den Beobachter ohne Störmodell bereits vorliegt. Es wird dargestellt, wie darauf basierend mit einfachen formelmäßigen Zusammenhängen die Rückführkoeffizienten für den Störgrößenbeobachter ermittelt werden können. Die beschriebene Methode erhöht die Übersichtlichkeit hinsichtlich des Einflusses des Störmodells auf die Beobachterrückführkoeffizienten und ist außerdem für Modelle mit geringer Systemordnung rechenzeitsparender.
Bach, Gas, Strom und Wasser
(2022)
Precisely synchronized communication is a major precondition for many industrial applications. At the same time, hardware cost and power consumption need to be kept as low as possible in the Internet of Things (IoT) paradigm. While many wired solutions on the market achieve these requirements, wireless alternatives are an interesting field for research and development. This article presents a novel IEEE802.11n/ac wireless solution, exhibiting several advantages over state-of-the-art competitors. It is based on a market-available wireless System on a Chip with modified low-level communication firmware combined with a low-cost field-programmable gate array. By achieving submicrosecond synchronization accuracy, our solution outperforms the precision of low-cost products by almost four orders of magnitude. Based on inexpensive hardware, the presented wireless module is up to 20 times cheaper than software-defined-radio solutions with comparable timing accuracy. Moreover, it consumes three to five times less power. To back up our claims, we report data that we collected with a high sampling rate (2000 samples per second) during an extended measurement campaign of more than 120 h, which makes our experimental results far more representative than others reported in the literature. Additional support is provided by the size of the testbed we used during the experiments, composed of a hybrid network with nine nodes divided into two independent wireless segments connected by a wired backbone. In conclusion, we believe that our novel Industrial IoT module architecture will have a significant impact on the future technological development of high-precision time-synchronized communication for the cost-sensitive industrial IoT market.
Inadequate mechanical compliance of orthopedic implants can result in excessive strain of the bone interface, and ultimately, aseptic loosening. It is hypothesized that a fiber-based biometal with adjustable anisotropic mechanical properties can reduce interface strain, facilitate continuous remodeling, and improve implant survival under complex loads. The biometal is based on strategically layered sintered titanium fibers. Six different topologies are manufactured. Specimens are tested under compression in three orthogonal axes under 3-point bending and torsion until failure. Biocompatibility testing involves murine osteoblasts. Osseointegration is investigated by micro-computed tomography and histomorphometry after implantation in a metaphyseal trepanation model in sheep. The material demonstrates compressive yield strengths of up to 50 MPa and anisotropy correlating closely with fiber layout. Samples with 75% porosity are both stronger and stiffer than those with 85% porosity. The highest bending modulus is found in samples with parallel fiber orientation, while the highest shear modulus is found in cross-ply layouts. Cell metabolism and morphology indicate uncompromised biocompatibility. Implants demonstrate robust circumferential osseointegration in vivo after 8 weeks. The biometal introduced in this study demonstrates anisotropic mechanical properties similar to bone, and excellent osteoconductivity and feasibility as an orthopedic implant material.
Am 1. Juli 2022 trafen sich im Rahmen des Abschlusskolloquiums des Projekts ACA-Modes rund 60 Teilnehmende aus Forschung, Lehre und Industrie zu einer internationalen Konferenz an der Hochschule Offenburg. Hier wurden die Projektergebnisse rund um die erfolgreiche Implementierung modellprädiktiver Regelstrategien vorgestellt, aktuelle Fragestellungen diskutiert und Entwicklungspfade hin zu einem netzdienlichen Betrieb von Energieverbundsystemen skizziert.
Die Optimierung der Auftragsterminierung und Einsteuerungsreihenfolge hat großen Einfluss auf die Produktivität von Fertigungssystemen. Genetische Algorithmen und Simulation sind verbreitete Werkzeuge zur Optimierung. Dieser Beitrag beschreibt einen neuen Ansatz zur Optimierung durch einen genetischen Algorithmus und der Simulation in dynamischen Modellen. Eine illustrative Fallstudie validiert den Ansatz und zeigt das Potenzial zur ganzheitlichen Verbesserung von Fertigungssystemen auf.
Unterschiedliche Stimulationszeitpunkte bei bimodaler Versorgung mit Hörgerät und Cochleaimplantat
(2023)
Die bimodale Versorgung von Patienten mit Hörgerät (HG) ipsilateral und Cochleaimplantat (CI) kontralateral bei asymmetrischem Hörverlust ist aufgrund vieler inhärenter Variablen die komplizierteste Versorgungsart im Kontext der Versorgung mit CI. Im vorliegenden Übersichtsartikel werden alle systematischen interauralen Unterschiede zwischen elektrischer und akustischer Stimulation dargestellt, die bei dieser Versorgungsart auftreten können. Darüber hinaus werden Methoden zur Quantifizierung des interauralen Latenzoffsets, also des Zeitunterschieds zwischen der akustischen und elektrischen Stimulation des Hörnervs, mittels Registrierung auditorisch evozierter Potenziale – erzeugt durch akustische bzw. elektrische Stimulation – und Messungen an den Sprachprozessoren und Hörgeräten vorgestellt. Die technische Kompensation des interauralen Latenzoffsets und ihre positive Auswirkung auf die Schalllokalisationsfähigkeit bimodal mit CI und HG versorgter Patienten wird ebenfalls beschrieben. Zuletzt werden neueste Erkenntnisse diskutiert, die Gründe dafür aufzeigen, warum die Kompensation des interauralen Latenzoffsets das Sprachverstehen im Störgeräusch bei bimodal versorgten CI-/HG-Trägern nicht verbessert.