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This work presents a new concept to implement the elliptic curve point multiplication (PM). This computation is based on a new modular arithmetic over Gaussian integer fields. Gaussian integers are a subset of the complex numbers such that the real and imaginary parts are integers. Since Gaussian integer fields are isomorphic to prime fields, this arithmetic is suitable for many elliptic curves. Representing the key by a Gaussian integer expansion is beneficial to reduce the computational complexity and the memory requirements of secure hardware implementations, which are robust against attacks. Furthermore, an area-efficient coprocessor design is proposed with an arithmetic unit that enables Montgomery modular arithmetic over Gaussian integers. The proposed architecture and the new arithmetic provide high flexibility, i.e., binary and non-binary key expansions as well as protected and unprotected PM calculations are supported. The proposed coprocessor is a competitive solution for a compact ECC processor suitable for applications in small embedded systems.
Die Projektaufgabe bestand darin, den aktuellen Laborversuch zu modernisieren, indem die Kommunikation zwischen dem Versuchsaufbau und Laborrechner nicht wie bisher über Wandlerkarten stattfindet, sondern über EtherCAT und TwinCAT 3.
Die Installation von TwinCAT 3 mit den zugehörigen Erweiterungen und erforderlichen Programmen stellt sich als sehr umfangreich und schwierig dar, was die Installationsanleitungen zeigen. Außerdem gab es sehr viele Fehlerquellen, die nicht auf Anhieb ersichtlich waren, wie das Aktualisieren der aktuellen MATLAB Version. Ist die Installation abgeschlossen kann die Kommunikation zwischen MATLAB und TwinCAT relativ einfach umgesetzt werden.
In der Projektarbeit wurde anfangs dann die Kommunikation mit mehreren Tests überprüft und Optimierungen vorgenommen. So wurde zum Beispiel die Wegbegrenzung angepasst. Schwierigkeiten zeigten sich bei der Bedienung über MATLAB oder beim Abstürzen von MATLAB, da beim Stoppen oder Abstürzen von MATLAB, der zuletzt gesendete Wert immer noch an TwinCAT 3 anliegt und somit der Aktor weiter verfahren würde. Diese sehr gefährliche Situation wäre ein gravierender Nachteil, gegenüber der alten Kommunikation mit einer Wandlerkarte. Um einen sicheren Stopp zu garantieren, wird über ein neues TcCOM Objekt der Matlab-Status mit einem Togglebit überprüft, ändert sich der Wert des Bits nicht mehr, stoppt die Anlage sicher.
Um einen Vergleich mit dem bisherigen Masterversuch erhalten zu können, wurde die Strecke mit der neuen Kommunikation untersucht und ein passender Regler dafür auszulegt.
Die Auswertung der Impulsantwort sowie der „Spectrum-Analyse“ zeigten beim Vergleich mit den Schnittstellen gleiche Ergebnisse, somit sind die Versuche bei dem Laborversuch ohne Einschränkungen durchführbar. Die Auslegung des Reglers zeigte entgegen den Prognosen der Beckhoff-Experten sehr gute Ergebnisse und die Kommunikation über die Schnittstelle zeigte keine Probleme.
Einschränkungen zeigten sich jedoch bei der einzustellenden Abtastzeit, da eine Abtastzeit unter 2ms nicht möglich ist. Zwar kann man eine geringere Abtastzeit einstellen, jedoch zeigt sich bei der Auswertung, dass die Schnittstelle mit Abtastzeiten unter 2ms Probleme aufweist. Die Rechendauer wird deutlich größer und die größere Anzahl an Messpunkte kann nicht richtig verarbeitet werden. Ein Regler kann damit nicht implementiert werden.
Die Projektarbeit konnte somit erfolgreich angeschlossen werden und bis auf die aufwendige Installation sind die Erweiterungen von Beckhoff sehr zuverlässig und gut zu bedienen. Die ersten Voruntersuchen waren positiv, somit kann auch an weiteren Laborrechnern eine Umstellung der Schnittstelle in Betracht gezogen werden.
Shared Field, Divided Field
(2020)
The IETF, concerned with the evolution of the Internet architecture, nowadays also looks into industrial automation processes. The contributions of a variety of IETF activities, initiated during the last ten years, enable now the replacement of proprietary standards by an open standardized protocol stack. This stack, denoted in the following as 6TiSCH-stack, is tailored for industrial internet of things (IIoTs). The suitability of 6TiSCH-stack for Industry 4.0 is yet to explore. In this paper, we identify four challenges that, in our opinion, may delay or hinder its adoption. As a prime example of that, we focus on the initial 6TiSCHnetwork
formation, highlighting the shortcomings of the default procedure and introducing our current work for a fast and reliable formation of dense network.
The recovery of our body and brain from fatigue directly depends on the quality of sleep, which can be determined from the results of a sleep study. The classification of sleep stages is the first step of this study and includes the measurement of vital data and their further processing. The non-invasive sleep analysis system is based on a hardware sensor network of 24 pressure sensors providing sleep phase detection. The pressure sensors are connected to an energy-efficient microcontroller via a system-wide bus. A significant difference between this system and other approaches is the innovative way in which the sensors are placed under the mattress. This feature facilitates the continuous use of the system without any noticeable influence on the sleeping person. The system was tested by conducting experiments that recorded the sleep of various healthy young people. Results indicate the potential to capture respiratory rate and body movement.
In my research sabbatical I was working on three different topics, namely orthogonal polynomials in geometric modeling, re-parametrized univariate subdivision curves, and reconstruction of 3d-fish-models and other zoological artifacts. In the subsequent Sections, I will describe my particular activity in these different fields. The sections are meant to present an overview of my research activities, leaving out the technical details.
Section 1 is on orthogonal polynomials and other related generating systems for functions systems of smooth function.
In Section 2, I will discuss the application of various re-parametrization schemes for interpolatory subdivision algorithms for the generation of space curves.
The next Section 3 is concerned with my research at the University of Queensland, Brisbane, in collaboration with Dr. Ulrike Siebeck from the School of Biomedical Sciences on fish behavior and reconstruction of 3d-fish models in particular.
In the last Section 4, I will describe what effects this research will have on in my subsequent teaching at the University of Applied Science Konstanz (HTWG).
Polysomnography is a gold standard for a sleep study, and it provides very accurate results, but its cost (both personnel and material) are quite high. Therefore, the development of a low-cost system for overnight breathing and heartbeat monitoring, which provides more comfort while recording the data, is a well-motivated challenge. The system proposed in this manuscript is based on the usage of resistive pressure sensors installed under the mattress. These sensors can measure slight pressure changes provoked during breathing and heartbeat. The captured signal requires advanced processing, like applying filters and amplifiers before the analog signal is ready for the next step. Then, the output signal is digitalized and further processed by an algorithm that performs a custom filtering before it can recognize breathing and heart rate in real-time. The result can be directly visualized. Furthermore, a CSV file is created containing the raw data, timestamps, and unique IDs to facilitate further processing. The achieved results are promising, and the average deviation from a reference device is about 4bpm.
Good sleep is crucial for a healthy life of every person. Unfortunately, its quality often decreases with aging. A common approach to measuring the sleep characteristics is based on interviews with the subjects or letting them fill in a daily questionnaire and afterward evaluating the obtained data. However, this method has time and personal costs for the interviewer and evaluator of responses. Therefore, it would be important to execute the collection and evaluation of sleep characteristics automatically. To do that, it is necessary to investigate the level of agreement between measurements performed in a traditional way using questionnaires and measurements obtained using electronic monitoring devices. The study presented in this manuscript performs this investigation, comparing such sleep characteristics as "time going to bed", "total time in bed", "total sleep time" and "sleep efficiency". A total number of 106 night records of elderly persons (aged 65+) were analyzed. The results achieved so far reveal the fact that the degree of agreement between the two measurement methods varies substantially for different characteristics, from 31 minutes of mean difference for "time going to bed" to 77 minutes for "total sleep time". For this reason, a direct exchange of objective and subjective measuring methods is currently not possible.
The evaluation of the effectiveness of different machine learning algorithms on a publicly available database of signals derived from wearable devices is presented with the goal of optimizing human activity recognition and classification. Among the wide number of body signals we choose a couple of signals, namely photoplethysmographic (optically detected subcutaneous blood volume) and tri-axis acceleration signals that are easy to be simultaneously acquired using commercial widespread devices (e.g. smartwatches) as well as custom wearable wireless devices designed for sport, healthcare, or clinical purposes. To this end, two widely used algorithms (decision tree and k-nearest neighbor) were tested, and their performance were compared to two new recent algorithms (particle Bernstein and a Monte Carlo-based regression) both in terms of accuracy and processing time. A data preprocessing phase was also considered to improve the performance of the machine learning procedures, in order to reduce the problem size and a detailed analysis of the compression strategy and results is also presented.
Gesellschaftsrecht
(2020)
Die vorliegende Veröffentlichung gibt einen kompakten Überblick über wesentliche Regelungen des Personen- und Kapitalgesellschaftsrechts. Nach den gesellschaftsrechtlichen Grundprinzipien werden zunächst die Personengesellschaften (GbR, OHG, KG, Stille Gesellschaft und Partnerschaft) und hieran anschließend die Kapitalgesellschaften (GmbH und AG) behandelt. Abschließend geht es um die diesbezüglichen Einflüsse des europäischen Rechts. Sie wendet sich in Lehrbuchform vornehmlich an Studierende von Universitäten, Hochschulen, Berufsakademien und anderen Bildungseinrichtungen.
The actual task of electrocardiographic examinations is to increase the reliability of diagnosing the condition of the heart. Within the framework of this task, an important direction is the solution of the inverse problem of electrocardiography, based on the processing of electrocardiographic signals of multichannel cardio leads at known electrode coordinates in these leads (Titomir et al. Noninvasiv electrocardiotopography, 2003), (Macfarlane et al. Comprehensive Electrocardiology, 2nd ed. (Chapter 9), 2011).
This article introduces the Global Sanctions Data Base (GSDB), a new dataset of economic sanctions that covers all bilateral, multilateral, and plurilateral sanctions in the world during the 1950–2016 period across three dimensions: type, political objective, and extent of success. The GSDB features by far the most cases amongst data bases that focus on effective sanctions (i.e., excluding threats) and is particularly useful for analysis of bilateral international transactional data (such as trade flows). We highlight five important stylized facts: (i) sanctions are increasingly used over time; (ii) European countries are the most frequent users and African countries the most frequent targets; (iii) sanctions are becoming more diverse, with the share of trade sanctions falling and that of financial or travel sanctions rising; (iv) the main objectives of sanctions are increasingly related to democracy or human rights; (v) the success rate of sanctions has gone up until 1995 and fallen since then. Using state-of-the-art gravity modeling, we highlight the usefulness of the GSDB in the realm of international trade. Trade sanctions have a negative but heterogeneous effect on trade, which is most pronounced for complete bilateral sanctions, followed by complete export sanctions.
Due to its economic size, economic policy measures, in particular trade policies, have a far‐reaching impact on global economic developments. This chapter quantifies the economic consequences of US protectionist trade aspirations. It focuses on trade policy scenarios, which have been communicated by the current US administration as potential new trade policies. The chapter draws on the results of a study of the ifo Institute conducted on behalf of the Bertelsmann Foundation. In the first simulation, a retraction from the North American Free Trade Agreement is considered. The chapter then illustrates the potential consequences of a “border tax adjustment” policy. It also simulates further measures to protect the US market by presuming an increase in American duties. The chapter presents robust quantitative results that can be expected if an increasingly protectionist US trade policy were to be implemented.
In diesem Beitrag wird eine Methode des maschinellen Lernens entwickelt, die die Schlafstadienerkennung untersucht. Übliche Methoden der Schlafanalyse basieren auf der Polysomnographie (PSG). Der präsentierte Ansatz basiert auf Signalen, die ausschließlich nicht-invasiv in einer häuslichen Umgebung gemessen werden können. Bewegungs-, Herzschlags- und Atmungssignale können vergleichsweise leicht erfasst werden aber die Erkennung der Schlafstadien ist dadurch erschwert. Die Signale werden als Zeitreihenfolge strukturiert und in Epochen überführt. Die Leistungsfähigkeit von maschinellem Lernen wird der Polysomnographie gegenübergestellt und bewertet.