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The main aim of presented in this manuscript research is to compare the results of objective and subjective measurement of sleep quality for older adults (65+) in the home environment. A total amount of 73 nights was evaluated in this study. Placing under the mattress device was used to obtain objective measurement data, and a common question on perceived sleep quality was asked to collect the subjective sleep quality level. The achieved results confirm the correlation between objective and subjective measurement of sleep quality with the average standard deviation equal to 2 of 10 possible quality points.
Introduction. Despite its high accuracy, polysomnography (PSG) has several drawbacks for diagnosing obstructive sleep apnea (OSA). Consequently, multiple portable monitors (PMs) have been proposed. Objective. This systematic review aims to investigate the current literature to analyze the sets of physiological parameters captured by a PM to select the minimum number of such physiological signals while maintaining accurate results in OSA detection. Methods. Inclusion and exclusion criteria for the selection of publications were established prior to the search. The evaluation of the publications was made based on one central question and several specific questions. Results. The abilities to detect hypopneas, sleep time, or awakenings were some of the features studied to investigate the full functionality of the PMs to select the most relevant set of physiological signals. Based on the physiological parameters collected (one to six), the PMs were classified into sets according to the level of evidence. The advantages and the disadvantages of each possible set of signals were explained by answering the research questions proposed in the methods. Conclusions. The minimum number of physiological signals detected by PMs for the detection of OSA depends mainly on the purpose and context of the sleep study. The set of three physiological signals showed the best results in the detection of OSA.
The McEliece cryptosystem is a promising candidate for post-quantum public-key encryption. In this work, we propose q-ary codes over Gaussian integers for the McEliece system and a new channel model. With this one Mannheim error channel, errors are limited to weight one. We investigate the channel capacity of this channel and discuss its relation to the McEliece system. The proposed codes are based on a simple product code construction and have a low complexity decoding algorithm. For the one Mannheim error channel, these codes achieve a higher error correction capability than maximum distance separable codes with bounded minimum distance decoding. This improves the work factor regarding decoding attacks based on information-set decoding.
Twenty-first century infrastructure needs to respond to changing demographics, becoming climate neutral, resilient and economically affordable, while remaining a driver for development and shared prosperity. However, the infrastructure sector remains one of the least innovative and digitalised, plagued by delays, cost overruns and benefit shortfalls (Cantarelli et al. 2008; Flyvbjerg, 2007; Flyvbjerg et al., 2003; Flyvbjerg et al., 2004). The root cause is the prevailing fragmentation of the infrastructure sector (Fellows and Liu, 2012). To help overcome these challenges, integration of the value chain is needed. This could be achieved through a use-case-based creation of federated ecosystems connecting open and trusted data spaces and advanced services applied to infrastructure projects. Such digital platforms enable full-lifecycle participation and responsible governance guided by a shared infrastructure vision. Digital federation enables secure and sovereign data exchange and thus collaboration across the silos within the infrastructure sector and between industries as well as within and between countries. Such an approach to infrastructure technology policy would not rely on technological solutionism but proposes the development of open and trusted data alliances. Federated data spaces provide access to the emerging data economy, especially for SMEs, and can foster the innovation of new digital services. Such responsible digital governance can help make the infrastructure sector more resilient, efficient and aligned with the realisation of ambitious decarbonisation and environmental protection targets. The European Union and the United States have already developed architectures for sovereign and secure data exchange.
Nowadays, the inexpensive memory space promotes an accelerating growth of stored image data. To exploit the data using supervised Machine or Deep Learning, it needs to be labeled. Manually labeling the vast amount of data is time-consuming and expensive, especially if human experts with specific domain knowledge are indispensable. Active learning addresses this shortcoming by querying the user the labels of the most informative images first. One way to obtain the ‘informativeness’ is by using uncertainty sampling as a query strategy, where the system queries those images it is most uncertain about how to classify. In this paper, we present a web-based active learning framework that helps to accelerate the labeling process. After manually labeling some images, the user gets recommendations of further candidates that could potentially be labeled equally (bulk image folder shift). We aim to explore the most efficient ‘uncertainty’ measure to improve the quality of the recommendations such that all images are sorted with a minimum number of user interactions (clicks). We conducted experiments using a manually labeled reference dataset to evaluate different combinations of classifiers and uncertainty measures. The results clearly show the effectiveness of an uncertainty sampling with bulk image shift recommendations (our novel method), which can reduce the number of required clicks to only around 20% compared to manual labeling.
Acoustic Echo Cancellation (AEC) plays a crucial role in speech communication devices to enable full-duplex communication. AEC algorithms have been studied extensively in the literature. However, device specific details like microphone or loudspeaker configurations are often neglected, despite their impact on the echo attenuation or near-end speech quality. In this work, we propose a method to investigate different loudspeaker-microphone configurations with respect to their contribution to the overall AEC performance. A generic AEC system consisting of an adaptive filter and a Wiener post filter is used for a fair comparison between different setups. We propose the near-end-to-residual-echo ratio (NRER) and the attenuation-of-near-end (AON) as quality measures for the full-duplex AEC performance.
Algorithms and Architectures for Cryptography and Source Coding in Non-Volatile Flash Memories
(2021)
In this work, algorithms and architectures for cryptography and source coding are developed, which are suitable for many resource-constrained embedded systems such as non-volatile flash memories. A new concept for elliptic curve cryptography is presented, which uses an arithmetic over Gaussian integers. Gaussian integers are a subset of the complex numbers with integers as real and imaginary parts. Ordinary modular arithmetic over Gaussian integers is computational expensive. To reduce the complexity, a new arithmetic based on the Montgomery reduction is presented. For the elliptic curve point multiplication, this arithmetic over Gaussian integers improves the computational efficiency, the resistance against side channel attacks, and reduces the memory requirements. Furthermore, an efficient variant of the Lempel-Ziv-Welch (LZW) algorithm for universal lossless data compression is investigated. Instead of one LZW dictionary, this algorithm applies several dictionaries to speed up the encoding process. Two dictionary partitioning techniques are introduced that improve the compression rate and reduce the memory size of this parallel dictionary LZW algorithm.
Kapitel 2 der vorliegenden Arbeit beschreibt die theoretischen Grundlagen optimaler Regelung und die unterschiedlichen Methoden des Pfadintegral Frameworks zur Reglersynthese. Zudem wird ein Ansatz zur Erweiterung des stochastischen NMPC dargestellt, sodass eine Adaption an eine real vorliegende Systemdynamik erfolgt. Weiter wird eine Methode entwickelt und beschrieben, welche die Effizienz des Algorithmus stark erhöht.
In Kapitel 3 wird aufgezeigt, wie die Pfadintegral Regelung dazu genutzt wird ein Furuta Pendel aufzuschwingen.
In Kapitel 4 werden die Algorithmen zur Lösung unterschiedlicher Problemstellungen im Kontext eines Forschungsboot appliziert. So wird unter anderem gezeigt, wie ein Pfadintegral Regelungsalgorithmus genutzt werden kann, um autonom mit dem Forschungsboot Solgenia am Steg der HTWG Konstanz anzulegen.
Abschließend wird in Kapitel 5 ein Fazit aus den Ergebnissen gezogen, diese eingeordnet und ein Ausblick auf weitere mögliche Arbeiten gegeben.
Die vorgestellte analytische Berechnungsmethode führt, unter Berücksichtigung desKraftschlusses, der Radsatzdimensionierungund der Dämpfungseigenschaft des Antriebssystems, zu einem konservativ berechnetendynamischen Torsionsmoment.Die ermittelten Abweichungen zeigenleicht gröβere Werte gegenüber der Messungund über einen breiten Parameterbereichtendenziell gröβere Werte gegenüber der Simulation. Demnach stellt die Methodeeinen pragmatischen Ansatz dar, dasmaximale, dynamische Torsionsmomentfür die Auslegung von Radsatzwelle ausreichendkonservativ zu berechnen.
Specific climate adaptation and resilience measures can be efficiently designed and implemented at regional and local levels. Climate and environmental databases are critical for achieving the sustainable development goals (SDGs) and for efficiently planning and implementing appropriate adaptation measures. Available federated and distributed databases can serve as necessary starting points for municipalities to identify needs, prioritize resources, and allocate investments, taking into account often tight budget constraints. High-quality geospatial, climate, and environmental data are now broadly available and remote sensing data, e.g., Copernicus services, will be critical. There are forward-looking approaches to use these datasets to derive forecasts for optimizing urban planning processes for local governments. On the municipal level, however, the existing data have only been used to a limited extent. There are no adequate tools for urban planning with which remote sensing data can be merged and meaningfully combined with local data and further processed and applied in municipal planning and decision-making. Therefore, our project CoKLIMAx aims at the development of new digital products, advanced urban services, and procedures, such as the development of practical technical tools that capture different remote sensing and in-situ data sets for validation and further processing. CoKLIMAx will be used to develop a scalable toolbox for urban planning to increase climate resilience. Focus areas of the project will be water (e.g., soil sealing, stormwater drainage, retention, and flood protection), urban (micro)climate (e.g., heat islands and air flows), and vegetation (e.g., greening strategy, vegetation monitoring/vitality). To this end, new digital process structures will be embedded in local government to enable better policy decisions for the future.
Text produced by entrepreneurs represents a data source in entrepreneurship research on venture performance and fund-raising success. Manual text coding of single variables is increasingly assisted or replaced by computer-aided text analysis. Yet, for the development of prediction models with several variables, such dictionary-based text analysis methods are less suitable. Natural language processing techniques are an alternative; however, the implementation is more complex and requires substantial programming skills. More work is required to understand how text analytics can advance entrepreneurship research. This study hence experiments with different artificial intelligence methods rooted in Natural Language Processing and deep learning. It uses 766 business plans to train a model for the automated measurement of transaction relations, a construct which is an indicator for new technology-based firm survival. Empirical findings show that the accuracy of construct measurement can be significantly increased with automated methods and improves with larger amounts of training data. Language complexity sets limits to the precision of automated construct measurement though. We therefore recommend a hybrid approach: making use of the inherent advantages of combining automated with human coding until the amount of training data is sufficiently large to substitute the human coding completely. The study provides insights into the applicability of different text analytics methods in entrepreneurship research and points at future research potential.
Auslegung von Radsatzwellen unter Berücksichtigung des maximalen, dynamischen Torsionsmoments
(2021)
Der vorgestellte Bericht verdeutlicht denEinfluss des dynamischen Torsionsmomentsinfolge von selbsterregten Radsatz-Torsionsschwingungen auf den Festigkeitsnachweisvon Radsatzwellen. Durch dieanalytische Berechnung des maximalen,dynamischen Torsionsmoments werdenkausale Zusammenhänge erkennbar, diebei der Dimensionierung von Radsätzenhilfreich sind. So führt eine Vergröβerungdes Radsatzwellendurchmessers aufgrundder zunehmenden Torsionssteifigkeitzwar zu höheren Momenten, bewirktaber gleichzeitig eine deutlich niedrigereVergleichsspannung. Durch gröβereDurchmesser der Radsatzwelle ist, infolgegeringerer Fugendrücke, allerdings auchmit einer Schwächung der Pressverbändezu rechnen. In jedem Fall sind im Hinblickauf den Festigkeitsnachweis kleine Radradienvorteilhaft. Sollten Radradius undRadsatzwellendurchmesser nicht optimiertwerden können, kann zur weiteren Absicherungdes Festigkeitsnachweises derWerkstoff EA4T verwendet werden.
Der Inhalt dieser Arbeit befasst sich mit der Verwendung von regionalen Ressourcen in Form von Erde. Diese soll als Baumaterial unter Anwendung der Stampflehmbauweise für
ökologischeres Bauen dienen. Damit der Baustoff den Ansprüchen heutiger Bauaufgaben gerecht wird, wird untersucht, mit welchen nachhaltigen Methoden die Erde stabilisiert werden kann. Darüber hinaus wird nach einem zukunftsweisenden Fertigungsverfahren
für den Stampflehmbau gesucht. Die Nutzung und Kombination dieser Aspekte bezeichnen wir als Erdbau 4.0, welcher unter anderem für das Maun Sciene Park Projekt in Botswana infrage kommen könnte.
Bittamo
(2021)
The Ethiopian state increasingly seeks to enlist putative ‘traditional authorities’ to lend legitimacy to policies and interventions in the southwestern peripheries of the country. The underlying assumptions do not accord with the perceptions of the local populations: among the Kara in the South Omo region, legitimacy is predicated upon duty and accountability, and higher degrees of public legitimacy are disconnected from authority and direct command over other people’s conduct. The office of the Kara bitti, the highest spiritual leader, thus proves intractable to such attempts at enlistment and has been little affected by the radical transformation of the Kara’s lives through increasing integration into the Ethiopian state over recent decades. But even as the office has changed little, the lives of those expected to assume the role of bitti has, and the duties of a bitti strongly constrain the office holder and limit their personal ambitions and participation in politics at the local, regional and national level.
Background:
One of the most promising health care development areas is introducing telemedicine services and creating solutions based on blockchain technology. The study of systems combining both these domains indicates the ongoing expansion of digital technologies in this market segment.
Objective:
This paper aims to review the feasibility of blockchain technology for telemedicine.
Methods:
The authors identified relevant studies via systematic searches of databases including PubMed, Scopus, Web of Science, IEEE Xplore, and Google Scholar. The suitability of each for inclusion in this review was assessed independently. Owing to the lack of publications, available blockchain-based tokens were discovered via conventional web search engines (Google, Yahoo, and Yandex).
Results:
Of the 40 discovered projects, only 18 met the selection criteria. The 5 most prevalent features of the available solutions (N=18) were medical data access (14/18, 78%), medical service processing (14/18, 78%), diagnostic support (10/18, 56%), payment transactions (10/18, 56%), and fundraising for telemedical instrument development (5/18, 28%).
Conclusions:
These different features (eg, medical data access, medical service processing, epidemiology reporting, diagnostic support, and treatment support) allow us to discuss the possibilities for integration of blockchain technology into telemedicine and health care on different levels. In this area, a wide range of tasks can be identified that could be accomplished based on digital technologies using blockchains.
Matrix methods for the computation of bounds for the range of a complex polynomial and its modulus over a rectangular region in the complex plane are presented. The approach relies on the expansion of the given polynomial into Bernstein polynomials. The results are extended to multivariate complex polynomials and rational functions.