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Institute
When a droplet is brought in contact with an undercooled surface, it wets the substrate and solidifies at the same time. The interplay between the phase transition effects and the contact-line motion, leading to its arrest, remains poorly understood. Here we reveal the early solidification patterns and dynamics of spreading hexadecane droplets. Total internal reflection imaging is employed to temporally and spatially resolve the early solidification behavior. With this, we determine the conditions leading to the contact-line arrest. We quantify the overall nucleation behavior, i.e., the nucleation rate and the crystal growth speed and show its sensitivity to the applied undercooling of the substrate. We also show that for strong enough undercooling it is the rapid growth of the crystals which determines the eventual arrest of the spreading contact line. By combining the Johnson-Mehl-Avrami-Kolmogorov nucleation theory and scaling relations for the spreading, we calculate the temporal evolution of the solid area fraction, which is in good agreement with our observations.
„Ich will loslegen!“ (IWL). Dieser Ausruf spiegelt die Motivation der befragten Unternehmer*innen zu einem Zeitpunkt wider, an dem sie sich entschlossen haben, ein erstes oder neues Digitalisierungsprojekt zu initiieren. Um aktiv eine Unterstützung für das Vorhaben anzufragen, beantworteten kleinste, kleine und mittlere Unternehmen (KKMU) die 100 Fragen des IST-1-Fragebogens. Unsere IWL-Studie beinhaltet die Analyse der Antworten der Unternehmer*innen und ermöglicht neue Erkenntnisse. Sie zeigt Bedürfnisse und Widersprüche im Hinblick auf Digitalisierungsvorhaben auf. Wo setzen KKMU ihren Fokus, wie handeln sie und welche Potenziale und Hürden offenbaren sich im Kontext digitaler Lösungen? Die verschiedenen Punkte werden in der vorliegenden Fassung anhand von Hypothesen erläutert und abschließend diskutiert.
Selbstbestimmte Identitäten
(2021)
Anordnung des HmbBfDI gegen Facebook - Dringlichkeitsanordnung statt Zusammenarbeit und Kohärenz?
(2021)
Steganographic and covert communication is increasingly used for hiding attacks. Often information hiding is used by attackers in advanced persistent threats in order to operate without being noticed. Attackers might use it to hide data exfiltration or control channels for persistent malware. The paper analyzes potential threats to operational technology by investigating different communication protocols towards their suitability as cover channels. Using a generalized network architecture model and the communication flows of nuclear power plants, the attack potential using information hiding is exemplary assessed. An example for a supply chain attack for command injection is given on the foundation of the OPC UA protocol and an off-theshelf programmable logic controller. Subsequently, recommendations for a strategic and operational preparation for operators towards the prevention and detection of information hiding attacks are derived.
The paper presents our public Gait Analysis Data Base (http://gaitanalysis.th-brandenburg.de), which contains 3D walking kinematics and muscle activity data from healthy adults walking at normal, slow or fast pace on the flat ground or at an incremental speeds on treadmill. The acceleration, angular velocity and magnetic rate vectors are measured using XSens MTw sensors attached to both feet, shanks, thighs and the pelvis. EMG recordings are acquired using PLUX sEMG sensors applied at various leg muscles. The paper gives not only a detailed description of the data base, its webpage and the used terms (scenario, proband, experiment and trial), but also an overview about the experimental setup, the acquisition of data and the procedure of the experiments, the data processing and evaluation. Results of exemplary applications are described in the second part of the paper.
Kill Chain Attack Modelling for Hidden Channel Attack Scenarios in Industrial Control Systems
(2020)
The paper presents a public available dataset acquired with wearable inertial measurement units (Xsens MTw) in various walking scenarios. The database provides preprocessed recordings including acceleration, angular velocity and magnetic rate vectors as well as the orientation quaternions. The paper describes the gait measurement system including the whole process chain from the choice of the measurement principle and devices, the data acquisition, the data processing and post-processing. Possible faults and prevention methods are analyzed. Exemplary, indicators of their effect are introduced and discussed.
A central idea of ubiquitous music is that music does not arise from the ideas of an isolated genius, but rather from the interaction of several participants [Keller et al. 2014]. But this requires a certain amount of restraint on the part of the designers of the respective setting and at the same time seems to require a full disclosure of the underlying theoretical and aesthetic concepts to the participants, if the participants are really to be taken seriously and given the means to actually be able to become creative themselves in an understandable way within the given context. In this paper, the consequences of such a demand are first discussed theoretically. Finally, for the concept developed by the author, ”Every human being can compose on the basis of natural numbers”, an attempt is made in this specific case to determine in what form such a concept could be passed on in order to meet the above criteria.
Steganography embraces several hiding techniques which spawn across multiple domains. However, the related terminology is not unified among the different domains, such as digital media steganography, text steganography, cyber-physical systems steganography, network steganography (network covert channels), local covert channels, and out-of-band covert channels. To cope with this, a prime attempt has been done in 2015, with the introduction of the so-called hiding patterns, which allow to describe hiding techniques in a more abstract manner. Despite significant enhancements, the main limitation of such a taxonomy is that it only considers the case of network steganography. Therefore, this paper reviews both the terminology and the taxonomy of hiding patterns as to make them more general. Specifically, hiding patterns are split into those that describe the embedding and the representation of hidden data within the cover object. As a first research action, we focus on embedding hiding patterns and we show how they can be applied to multiple domains of steganography instead of being limited to the network scenario. Additionally, we exemplify representation patterns using network steganography.
Der Erwartungswert einer Zufallsgröße kann generell am Graphen ihrer Verteilungsfunktion durch eine naheliegende Gleichheit zweier Flächeninhalte festgelegt werden. Äquivalent dazu lässt er sich mit zwei uneigentlichen Riemann-Integralen darstellen. Davon ausgehend werden die Tschebyschow-Ungleichung und ihre Modifikation mit strikten Ungleichheitszeichen hergeleitet.
Smectic films in a collapsing catenoid develop spontaneous wrinkling patterns like solid sheets.
Smectic freely-suspended films can wrinkle like solid sheets. This has been demonstrated earlier with shape-fluctuating smectic bubbles. Here, we exploit the collapse of smectic catenoid films with a central equatorial film to expose the latter to rapid lateral compression. Wrinkle formation is observed in the planar film and the thickness dependence of the undulation wavelength is measured. In addition to the central film, its border undergoes an undulation instability as well.
Dieser Beitrag entwickelt ein Konzept zur praktischen Umsetzung eines Machine- Learning Verfahrens zum Lösen von Vehicle Routing Problemen im Kontext einer nachhaltigen “Letzte-Meile”-Logistik, welches durch einen Prototyp umgesetzt und getestet wurde. Der Prototyp basiert auf dem “Reinforcement Learning”-System und verwendet als Algorithmus “REINFORCE mit Baseline”. In einer Vergleichsanalyse wurde der Prototyp mit dem bekannten Vertreter Google-OR, anhand von zwei Anwendungsszenarien, verglichen. Der Prototyp überzeugt dabei in der Laufzeit und dem Automatismus. Es konnte festgestellt werden, dass eine Verwendung von Lernenden-Systemen für das Vehicle Routing Problem sich bei nur bei einem größeren Stoppvolumen und einer erweiterten IT-Infrastruktur empfiehlt.
A unified understanding of terms and their applicability is essential for every scientific discipline: steganography is no exception. Being divided into several domains (for instance, text steganography, digital media steganography, and network steganography), it is crucial to provide a unified terminology as well as a taxonomy that is not limited to some specific applications or areas. A prime attempt towards a unified understanding of terms was conducted in 2015 with the introduction of a pattern-based taxonomy for network steganography. Six years later, in 2021, the first work towards a pattern-based taxonomy for steganography was proposed. However, this initial attempt still faced several shortcomings, e.g., the lack of patterns for several steganography domains (the work mainly focused on network steganography and covert channels), various terminology issues, and the need of providing a tutorial on how the taxonomy can be used during engineering and scientific tasks, including the paper-writing process.</p>
<p>As the consortium who published this initial 2021-study on steganography patterns, in this paper we present the first comprehensive pattern-based taxonomy tailored to fit all known domains of steganography, including smaller and emerging areas, such as filesystem steganography and cyber-physical systems steganography. Besides, to make our contribution more effective and promote the use of the taxonomy to advance research on steganography, we also provide a thorough tutorial on its utilization. </p>
<p>Our pattern collection is available at <a href="https://patterns.ztt.hs-worms.de/" target="_blank">https://patterns.ztt.hs-worms.de</a>.</p>
Fast protein and metabolite liquid chromatography (FPLMC) was introduced years ago to enable the easy separation of high-molecular compounds such as proteins from small molecules and the identification of the low-molecular substances. In this paper, the method is applied for the rapid evaluation of freshness and monitoring the aging of animal meat and fish. A novel chromatographic sensor was developed with a deep UV LED-based photometric detection unit (255–265 nm), an original flow cuvette and registration scheme; the processing of a chromatogram with the sensor takes approximately 15 min. Strict isochronism between the elution of ATP metabolites, mainly hypoxanthine (Hx) and inosine monophosphate (IMP), and the time of maturation of meat or fish, was discovered. A new freshness index H* = [Hx]/[IMP] was introduced, which is proportional to the instrumental delay time in the FPMLC chromatograms: the H* index < 0.5 indicates the presence of inosine monophosphate (IMP) and the high quality of the meat or fish. Reasonably strong correlations were revealed between data obtained by FPMLC and total volatile basic nitrogen TVB-N (for fish) or volatile fatty acids VFA (for meat) content. Moreover, putative nucleotide salvage and an increase in the concentration of IMP were observed in fish after heat treatment using the FPMLC sensor and NMR technique.
A sample set of calculations is presented in this supplemental document to analytically estimate joint distortion for gas metal arc lap joining of aluminum and steel thin sheets following the published article "Analytical Estimation of Thermomechanical Distortion and Interface Layer Thickness for Gas Metal Arc Lap Joining of Dissimilar Sheets"
Due to the increasing number of complaints alleging privacy violations against companies to data protection authorities, the translation of business goals to system design goals and the subsequent consequences for customers’ privacy poses a challenge for many companies. For this reason, there is a need to bridge the economics of privacy and threats to privacy. To this end, our work relies on the concept of privacy as contextual integrity. This framework defines privacy as appropriate information flows subjected to social norms within particular social contexts or spheres. In this paper, we introduce a preliminary version of a semantic model which aims to relate and provide understanding on how well-established business goals may affect their customers’ privacy by designing IoT devices with permission access, data acquired by sensors, among other factors. Finally, we provide a use case application showing how to use the semantic model. The model aims to be an educational tool for professionals in business informatics during the modeling and designing process of a product which may gather sensitive data or may infer sensitive information, giving an understanding of the interaction of the product and its footprint with diverse actors (humans or machines). In the future, a further complete model of the presented may also target other groups, such as law enforcement bodies, as part of their educational training in such systems.
4.1.: Grundlagen
(2022)
4.2.: Sicherheit
(2023)
Der vorliegende Beitrag befasst sich mit den Herausforderungen, die im Rahmen von Remote Work
in Kooperationen bezüglich der Informations- und
IT-Sicherheit bestehen, insbesondere im Hinblick auf
den sicheren Datenaustausch. Des Weiteren wird die
Wichtigkeit einer ganzheitlichen Sicht von IT-Governance-, Risiko- und Compliance-Management in Verbünden kleiner und mittlerer Unternehmen (KMU)
behandelt. Weiterhin wird aufgezeigt, was bei der
informationstechnischen Absicherung von Kooperationen und IT-Konsortien beachtet werden sollte.
In dieser Forschung wird es gezeigt, wie sicher und benutzerfreundlich eine Authentifizierung mit Passkey/FIDO2 auf Ebene des Web-Browsers ist, im Vergleich zu einer Authentifizierung mit einem starken Passwort oder eine Authentifizierung aus einer Kombination von einem Passwort und einer Zwei-Faktor-Authentifizierung.
In der heutigen digitalisierten Welt spielt die Sicherheit von IT-Infrastrukturen eine
entscheidende Rolle. Diese Bachelorarbeit untersucht das Potenzial von Network
Access Control (NAC) als eine IT-Lösung zur Verbesserung der Netzwerksicherheit in
modernen IT-Umgebungen. Dabei steht die Zugriffskontrolle von Personen und
Geräten im Vordergrund. Damit soll erreicht werden, dass unautorisierter Zugriff zum
Netzwerk verhindert wird. Es werden die Begrifflichkeiten, Funktionsweise und
potenzielle Angriffsvektoren von NAC untersucht. Des Weiteren werden die jeweiligen
Funktionen der NAC-Produkte macmon und der Open-Source Lösung PacketFence
gegenübergestellt. Im praktischen Teil der Arbeit werden dann die vorgestellten
Angriffsvektoren an einem Test-Netzwerk durchgeführt und analysiert.
Die Arbeit zeigt, dass NAC eine wichtige Komponente in der Zugriffskontrolle für eine
moderne IT-Infrastruktur ist. Während einige Angriffe auf das Test-Netzwerk
abgewehrt werden konnten, war es dennoch möglich, sich als Angreifer am Netzwerk
anzumelden. NAC ist ein unerlässliches Tool für größere IT-Infrastrukturen, jedoch
erfordert eine korrekte Konfiguration und effektive Nutzung von NAC ein
umfangreiches Wissen über die verschiedenen Aspekte und Themenbereiche der
Netzwerksicherheit.