Technische Hochschule Lübeck
  • Lübeck, Schleswig-Holstein, Germany
Recent publications
Der Arbeitsplatz – die räumlichen, physikalischen und ergonomischen Bedingungen, unter denen Menschen arbeiten – kann auf vielfältige Weise die Gesundheit fördern und gefährden. Neben der direkten Wirkung auf die physische Gesundheit kann der Arbeitsplatz die Durchführung der Arbeitsaufgaben erleichtern oder behindern und das Wohlbefinden durch eine bedürfnisgerechte Gestaltung erhöhen. Die Gestaltung gesundheitsförderlicher Arbeitsplätze beinhaltet den Arbeitsraum und die dort herrschenden physikalischen Bedingungen ebenso wie die Möblierung und IT-Ausstattung.
In radio-frequency (RF)-based device-free localization (DFL), the number of sensors acting as RF transmitters and receivers is crucial for accuracy and system costs. Two promising approaches for DFL have been identified in the past: radio tomographic imaging (RTI) and multi-static radar (MSR). RTI in its basic version requires many sensors for high accuracy, which increases the cost. In this paper, we show how RTI benefits from multipath propagation. By evaluating the direct and echo paths, we increase the coverage of the target area, and by utilizing UWB signals, the RTI system is less susceptible to multipath propagation. MSR maps reflections that occur within the target area to reflectors such as persons or other objects. MSR does not require that the person is located near a signal path. Both suggested methods exploit ultra-wideband (UWB) channel impulse response (CIR) measurements. CIR measurements and the modeling of multipath effects either increase the accuracy or reduce the required number of sensors for localization with RTI. We created a test setup and measure UWB CIRs at different positions with a commercially available off-the-shelf UWB radio chip, the Decawave DW1000. We compare the localization results of RTI, multipath-assisted (MA)-RTI, and MSR and investigate a combined approach. We show that RTI is improved by the analysis of multipath propagation; furthermore, MA-RTI results in a better performance compared to MSR: with 50% of all cases, the localization error is better than 0.82 m and in 80% of all cases 1.34 m. The combined approach results in the best localization result with 0.64 m in 50% of all cases.
Improving the accuracy and enabling traceable measurements of volume, flow, and pressure in existing drug delivery devices and in-line sensors operating at very low flow rates is essential in several fields of activities and specially in medical applications. This can only be achieved through the development of new calibrationmethods and by expanding the existing metrological infrastructure to perform micro-flow and nano-flow measurements. In this paper, we will investigate new traceable techniques for measuring flow rate, from 5 nL/min to 1,500 nL/min and present the results of an inter-comparison between nine laboratories for the calibration of two different flow meters and a syringe pump.
Die Bemessung von horizontal belasteten Pfählen erfolgt in Deutschland i.d.R. mit dem vereinfachten Bettungsmodulverfahren oder dem Verfahren nach BLUM. Hiermit können Pfahlkopfverschiebungen jedoch häufig nicht hinreichend genau prognostiziert werden. International werden nichtlineare Federkennlinien zur Abbildung des Bettungsverhaltens des Bodens verwendet, welches als p‐y‐Verfahren bezeichnet wird. In diesem Aufsatz werden die Grundlagen des p‐y‐Verfahrens vorgestellt und auf die Herleitung der einzelnen Modelle für unterschiedliche Bodenarten sowie die mathematische Beschreibung der jeweiligen p‐y‐Kurven eingegangen. Zur Berücksichtigung geschichteter Böden wird der Ansatz nach Georgiadis verwendet. Der mit diesem Verfahren ermittelte Erdwiderstand wird mit Berechnungen für den räumlichen Erdwiderstand nach DIN 4085 verglichen. Da in der DIN 4085 nur Formelansätze für homogene Böden angegeben sind, werden die entsprechenden Formeln für geschichtete Böden erweitert. Im Rahmen einer Parameterstudie an typischen Baugrundschichtungen werden die maßgebenden Unterschiede der einzelnen Verfahren aufgezeigt und diskutiert. P‐Y method in multilayered soils for predicting the horizontal pile displacement The design of laterally loaded piles in Germany is based on a simplified subgrade reaction modulus or the method by BLUM. With these methods the lateral pile deflection cannot be calculated very accurately. Internationally the so‐called p‐y approach is widely used, which is based on nonlinear spring stiffnesses to define the subgrade reaction modulus. In this paper the p‐y approach is described in detail and the application of each calculation model is discussed. For the consideration of the effect from multi‐layered soils the approach by Georgiadis is used. The earth resistance determined by this procedure is then compared with the spatial earth resistance from DIN 4085. Because DIN 4085 just offers equations for homogenous soils, the relevant equations are extended for layered soils. In a parameter study on typical soil conditions the decisive differences of the individual approaches are shown and discussed.
The current digital transformation, called Industry 4.0 and representing the fourth industrial revolution in manufacturing and industry, influences production of goods and services as well as value chains and business models. Automation, Big Data, AI (artificial intelligence) and IoT (Internet-of-Things) are technologies within Industry 4.0 that create so-called Smart Factories allowing the manufacturer to control the entire production from one platform. In the future, IoT will play a central role in every-day life and it will open new business and market opportunities as well as it will give market actors room for being active creators.
Der Arbeitsstil des Malers Georg Grosz dient als Ausgangspunkt um zu zeigen, wie sich ein spezifischer Arbeitsbereich – Textverarbeitung – in den letzten Jahrzehnten verändert hat und welche Folgewirkungen sich daraus ergeben können. Nach einer kurzen Erläuterung des Digitalisierungsbegriffs werden Produkte und Systeme der Digitalisierung im Überblick beschrieben. Abschließend werden die Inhalte der Kapitel des vorliegenden Buchteils zusammenfassend wiedergegeben.
Digitale Gesundheitsangebote stellen aufgrund geringerer örtlicher und zeitlicher Hürden eine flexible Alternative zu herkömmlichen Methoden dar. Dies gilt z. B für Online-Plattformen, die u. a. umfängliche Trainings mit Assessments und automatisierten Antwortsystemen bieten. Auch das Angebot an Gesundheits-Apps ist vielfältig, bspw. zum Zwecke der Prävention oder der Diagnose. Die Funktionalität von Smartphone-Apps kann zudem mit Hilfe von Applikationen auf einer Smartwach erweitert werden. Damit können u. a. verschiedene Vitaldaten erhoben und in einem Ernstfall ein automatischer Notruf abgesetzt werden. Die Virtual Reality (VR)-Technologie wird im Rahmen einer digitalen Konfrontationstherapie eingesetzt, bietet damit finanzielle, zeitliche und organisatorische Vorteile im Vergleich zu real durchzuführenden Therapien. Allen Vorteilen digitaler Gesundheitsangebote stehen Bedenken hinsichtlich des Datenschutzes gegenüber, dem ein ähnlicher Stellenwert wie der ärztlichen Schweigepflicht beigemessen werden sollte.
Agilität ist die Fähigkeit, in chaotischen und dynamischen Situationen schnell und flexibel zu reagieren, indem zum Nutzen für die Kund*innen eine Balance zwischen Strukturierung und Flexibilität geschaffen wird. Agile Arbeitsmethoden haben ihren Ursprung in der Softwareentwicklung, werden aber zunehmend in anderen Bereichen eingesetzt. Sie versprechen, in einer komplexer werdenden Welt möglichst kund*innenorientierte Lösungen zu finden. Agile Projektmanagementmethoden wie Scrum und Kanban zeichnen sich durch Merkmale wie Kund*innenzufriedenheit durch Teillieferungen, kurze Entwicklungszyklen, Fokus auf technischer Exzellenz und Design sowie funktionierende Teilprodukte aus. Selbststeuerung und Selbstorganisation sind wichtige Schlüssel für das Funktionieren agiler Arbeit. Gleichwohl stellen besonders diese Aspekte Beschäftigte vor besondere Herausforderungen, was Verantwortungsübernahme, Flexibilität und mögliche Folgebelastungen betrifft. Der Artikel zeigt auf, wie gezielte agile Methoden in nicht-klassischen Bereichen wie der sozialen Arbeit aussehen und wirken können und welche Rahmenbedingungen für ein gesundes Vorgehen in Organisationen wichtig sind.
Digitalisierung und Industrie 4.0 sind populäre Themen mit einer langen Tradition, denn seit Jahrzehnten wird die Diskussion zu Technikentwicklung als wesentlicher Teil der Entwicklung der Arbeitsgesellschaft geführt. Viele Erkenntnisse, die in diesem Zusammenhang erarbeitet wurden, sind für die aktuelle Auseinandersetzung über die Folgen von Digitalisierung und Industrie 4.0 von Bedeutung. Die Implikationen, die Digitalisierung für die Arbeitsorganisation, die Arbeitsverhältnisse, die Arbeitsbedingungen, die Balance zwischen verschiedenen Lebensbereichen hat, sind maßgeblich für die Gesundheit der Arbeitenden. Gesundheitsförderung und die Gestaltung guter Arbeit im Zeitalter der Digitalisierung bauen auf diesen Erkenntnissen auf und erweitern sie.
Digitalisierung ist mit weitreichenden Veränderungen in der Arbeitswelt verbunden. Das Kapitel greift zentrale Themen, die im wissenschaftlichen und Praxisdiskurs behandelt werden, auf. Anforderungen an soziotechnische Gestaltung, Ergonomie, elektronische Kommunikation und virtuelle Teams, sowie an Flexibilisierung und Entgrenzung von Arbeit werden zusammenfassend charakterisiert. Es folgt ein Überblick über die Kapitel in diesem Abschnitt, die Potentiale und Herausforderungen der Digitalisierung in verschiedenen Handlungsfeldern beleuchten.
Das folgende Kapitel unterscheidet individuelle, betriebliche und gesellschaftliche Aufgabenbereiche bei der Gestaltung digitaler Arbeit. Individuelle Kernaufgaben umfassen persönliche, soziale und technikorientierte Kompetenzen. Digital Arbeitende müssen Arbeitsgestaltungskompetenz erwerben, die es ihnen ermöglicht, den eigenen Arbeitsplatz, die Arbeitsaufgabe, Arbeitsmittel, die Arbeitsumgebung aber auch die Arbeitszeit und die soziale Situation möglichst belastungsarm und gleichzeitig ressourcenreich zu gestalten. Regeln zur Datensicherheit und zum Datenschutz müssen bekannt sein und eingehalten werden. Die Vermittlung des entsprechenden Wissens und die Schaffung von Rahmenbedingungen, in denen dieses Wissen auch umgesetzt werden kann, sind betriebliche Kernaufgaben. Der betriebliche Fokus ist darauf gerichtet, digitale Arbeit humanzentriert, d. h. schädigungslos, gesundheits- und persönlichkeitsförderlich zu gestalten und den Gestaltungsprozess an die Bedingungen digitaler Arbeit anzupassen. Neue Gestaltungsakteure wie z. B. Softwareentwickler*innen oder auch Anbieter*innen von Coworking Spaces sind zukünftig stärker zu berücksichtigen. Auf gesellschaftlicher Ebene müssen verschiedene Gruppen und Positionen in einen breiten Diskurs zur digitalen Zukunft einbezogen werden. Übergeordnete Rahmenbedingungen sind durch Wissenschaft, Politik und Gesetzesvorgaben zu regeln. Die digitale Transformation benötigt eine humanzentrierte Gestaltungskultur, die das Gemeinwesen und einen verantwortungsvollen Umgang mit Technik in den Mittelpunkt stellt.
Objective: To investigate the impact of metabolic status on choroidal thickness (ChT) in healthy subjects, patients with obesity, and type 2 diabetes. Design and methods: Fasting blood glucose, insulin, insulin-like growth factor-1 (IGF-1), and ChT measured by optical coherence tomography were assessed in healthy normal-weight (n=17), obese participants (n=20), and obese participants with T2D (n=16). Results: ChT increased in obese participants and obese participants with T2D as compared to healthy normal-weight participants (P<0.0001). A negative correlation was observed between IGF1 and ChT (r=-0.268, P=0.050) for all cohorts. Furthermore, body mass index (BMI; R2=0.209; P=0.002; beta=0.388) and model assessment-estimated insulin resistance (HOMA-IR; R2=0.074; P=0.015; beta=0.305) were independent variables of ChT, explaining 20.9 and 7.4% of its variance (both p<0.016), whereas age, sex, and IGF-1 were not significant confounders of ChT (p>0.975). Conclusion: ChT is associated with metabolic characteristics, i. e., BMI and HOMA-IR. Due to the key role of choroidal function in retinal physiology, future studies are needed to evaluate whether metabolic traits, ChT, and potential metabolic eye complications are mechanistically linked.
Spatial noise reduction algorithms (“beamformers”) can considerably improve speech reception thresholds (SRTs) for bimodal cochlear implant (CI) users. The goal of this study was to model SRTs and SRT-benefit due to beamformers for bimodal CI users. Two existing model approaches varying in computational complexity and binaural processing assumption were compared: (i) the framework of auditory discrimination experiments (FADE) and (ii) the binaural speech intelligibility model (BSIM), both with CI and aided hearing-impaired front-ends. The exact same acoustic scenarios, and open-access beamformers as in the comparison clinical study Zedan et al. (2021) were used to quantify goodness of prediction. FADE was capable of modeling SRTs ab-initio, i.e., no calibration of the model was necessary to achieve high correlations and low root-mean square errors (RMSE) to both, measured SRTs (r = 0.85, RMSE = 2.8 dB) and to measured SRT-benefits (r = 0.96). BSIM achieved somewhat poorer predictions to both, measured SRTs (r = 0.78, RMSE = 6.7 dB) and to measured SRT-benefits (r = 0.91) and needs to be calibrated for matching average SRTs in one condition. Greatest deviations in predictions of BSIM were observed in diffuse multi-talker babble noise, which were not found with FADE. SRT-benefit predictions of both models were similar to instrumental signal-to-noise ratio (iSNR) improvements due to the beamformers. This indicates that FADE is preferrable for modeling absolute SRTs. However, for prediction of SRT-benefit due to spatial noise reduction algorithms in bimodal CI users, the average iSNR is a much simpler approach with similar performance.
Estimation of the different types of heat fluxes at earth’s surface is critical in energy budget calculation and climate change impacts. 40 years (1979–2018) seasonal spatial and temporal analysis of heat flux from the American Land Data Assimilation System, phase 2 (NLDAS-2) over the United States of America (USA) is presented. Two types of heat fluxes are investigated: Sensible heat flux and latent heat flux. Sensitivity of NLDAS-2 to the two integrated different land surface models (LSMs); NOAH, MOSAIC are shown in terms of the calculated three types of heat fluxes. The spatial maps’ analysis revealed that the estimated sensible and latent heat fluxes from both models have different distribution, while the temporal analysis revealed that NLDAS with NOAH estimate higher sensible heat flux and lower latent heat flux than NLDAS coupled with MOSIAC.
Ordinary Portland cement (OPC) is known for its significant contribution to carbon dioxide emissions. Geopolymer has a lower footprint in terms of CO2 emissions and has been considered as an alternative for OPC. A well-developed understanding of the use of fly-ash-based and slag-based geopolymers as separate systems has been reached in the literature, specifically regarding their mechanical properties. However, the microstructural and durability of the combined system after slag addition introduces more interactive gels and complex microstructural formations. The microstructural changes of complex blended systems contribute to significant advances in the durability of fly ash/slag geopolymers. In the present review, the setting time, microstructural properties (gel phase development, permeability properties, shrinkage behavior), and durability (chloride resistance, sulfate attack, and carbonatation), as discussed literature, are studied and summarized to simplify and draw conclusions.
The production of battery materials has been identified as the main contributor to the greenhouse gas (GHG) emissions of lithium-ion batteries for automotive applications. Graphite manufacturing is characterized by energy intense production processes (including extraction), mainly being operated in China with low energy prices and a relatively high GHG emission intensity of electricity generation. Industrial scale primary data related to the production of battery materials lacks transparency and remains scarce in general. In particular, life cycle inventory datasets related to the extraction, refining and coating of graphite as anode material for lithium-ion batteries are incomplete, out of date and hardly representative for today's battery applications. Nevertheless, primary life cycle inventory data of battery materials like graphite, produced on an industrial scale are crucial for a robust evaluation of batteries for electric vehicles, material sourcing and development of robust decarbonization strategies. This paper addresses this issue by first providing a comprehensive overview of the existing graphite datasets and their original sources, and outlining the reasons for wide variations of reported environmental impact results. Furthermore, this paper aims at closing existing data gaps by providing transparent primary data from a Chinese graphite producer from 2019 and assessing the environmental impacts (cradle-to-gate) in form of a life cycle assessment (LCA) for a vertically integrated graphite production. The life cycle inventory covers material, water, energy flows and direct emissions associated with the production of natural graphite anode material for an automotive battery application and associated transport activities along the supply chain. The results of the LCA show that the production of 1000 kg of natural graphite anode material has a global warming potential (GWP) of approximately 9616 kg CO2eq. The subsequent uncertainty analysis in the form of a Monte-Carlo-Analysis with 10000 runs reveals that the 95% confidence interval is in the range between 9297 and 9940 kg CO2eq. This value is more than four times higher than the reported GWP of battery-grade graphite in the ecoinvent database version 3.7.1.
Purpose The increase of shellfish production has raised environmental concerns, i.e., enrichment and redistribution of nutrients and energy consumption. Efforts assessing the environmental burdens arising from the expansion of shellfish production have been made using the life cycle assessment (LCA) methodology. Although LCA has been extensively applied and reviewed in aquaculture systems, shellfish production remains scarcely studied. The objective of this review is to identify methodological trends, highlight gaps and limitations, and provide guidelines for future studies. Methods A systematic literature review was applied to scientific studies published up to 2021. A total of 13 documents were shorted by abstract and full text-screening. Literature meeting the inclusion criteria were further analyzed in six different aspects of a LCA (functional unit, system boundaries, data and data quality, allocation, impact assessment methods, interpretation methods). Discussion and guidelines are provided for each reviewed aspect. Results and discussions Shellfish LCAs differ considerably from other aquaculture studies mainly because shellfish avoids the allocation of impacts derived from the production of fishmeal. Co-products are present when the shellfish is processed, e.g., in canned products. Furthermore, shellfish studies do not take into account the positive credits from the removal of nutrients from the ecosystems and from the valorization of the shellfish waste (shell and organic remains). Limited information was found for countries outside Europe and species different from mussels. Despite the variability on goals and scopes of the studies, methodological trends were found. The local impacts of the shellfish with the farming area and the impacts on biodiversity have not been included into the studies. Conclusions and recommendations Effort should be made in providing the data associated with the fore-background system within the studies in order to improve transparency and to allow the reproduction of the results. Information regarding the natural condition of the cultivation area should be provided as the shellfish production depends mainly on non-anthropogenic conditions. Application of biodiversity assessment methodologies should be encouraged, despite their limitations.
In acoustic underwater communication and sonar applications, obstacles inside and outside the line-of-sight (LOS) affect signal propagation. Both reflection and diffraction occur in underwater communication and measurement systems due to these obstacles. To the best of our knowledge, the influence of diffraction and reflection is neither described nor modeled for finite pulses yet. We propose and develop a multipath propagation model for spectral diffraction components and phase information of the received signal based on knife-edge diffraction together with reflections, transmission effects, and backscatter. This paper designs a short range underwater ultrasonic experimental system composed of an ultrasonic transceiver with wideband pulses and advanced spectral signal processing. We evaluate our proposed model with measurements made in a water tank with an obstacle moved between the transmitter and receiver. When the model includes all major propagation components and effects, it achieves an accuracy for localization of 97 % of the results in the range of twice the obstacle diameter in our test setup.
Institution pages aggregate content on ResearchGate related to an institution. The members listed on this page have self-identified as being affiliated with this institution. Publications listed on this page were identified by our algorithms as relating to this institution. This page was not created or approved by the institution. If you represent an institution and have questions about these pages or wish to report inaccurate content, you can contact us here.
855 members
Anja Lorenz
  • Institute for Interactive Systems
Veronika Hellwig
  • School of Biochemical Engineering
Tim Jürgens
  • Angewandte Naturwissenschaften, Institut für Akustik
Information
Address
Mönkhofer Weg 239, 23562, Lübeck, Schleswig-Holstein, Germany
Head of institution
Dr. Muriel Helbig
Website
https://www.th-luebeck.de