Open Access

Because of their resilience, Time-of-Flight (ToF) cameras are now essential components in scientific and industrial settings. This paper outlines the essential factors for modeling 3D ToF cameras, with specific emphasis on analyzing the phenomenon known as “wiggling”. Through our investigation, we demonstrate that wiggling not only causes systematic errors in distance measurements, but also introduces periodic fluctuations in statistical measurement uncertainty, which compounds the dependence on the signal-to-noise ratio (SNR). Armed with this knowledge, we developed a new 3D camera model, which we then made computationally tractable. To illustrate and evaluate the model, we compared measurement data with simulated data of the same scene. This allowed us to individually demonstrate various effects on the signal-to-noise ratio, reflectivity, and distance.

Bei der Entwicklung von Kunststoffbauteilen kommen in kontinuierlich zunehmendem Maße Simulationen zum Einsatz. Vor dem Hintergrund von steigenden Produktanforderungen als auch dem unausweichlichen Zwang zur Schonung von Ressourcen ist der erweiterte Einsatz von Simulationswerkzeugen wichtiger Teil des Lösungsweges. Zu den nutzbaren, aber in Bezug zu Realprozessen bisher wenig eingesetzten Methoden gehört die Molekulardynamik Simulation. Auf Grundlage dieser Methode können auf mikroskopischer Ebene die tatsächlichen physikalischen Abläufe, die bei der Verarbeitung von Kunststoffen im Prozess auftreten, sichtbar gemacht werden. In dieser Arbeit wird beleuchtet, wie Randbedingungen in Anlehnung an den Extrusionsblasformprozess den Werkstoff Polyethylen auf mikroskopischer Ebene beeinflussen. Hierzu wird ein mesoskopisches Modell (Coarse-Graining) zur Beschreibung des Polymers genutzt. Dieses Modell wird durch die Bestimmung von Materialkennwerten verifiziert. Es wird der uniaxiale Zugversuch auf der Mikroskala modelliert, um Größen wie beispielsweise Elastizitätsmodul, Streckspannung oder Querkontraktionszahl zu ermitteln. Ebenso werden thermische Kenngrößen, insbesondere zur Charakterisierung des Kristallisationsverhaltens, bestimmt. Ziel dieser Untersuchungen ist, Effekte, die bei dynamisch ablaufenden Dehnungs- bzw. Kristallisationsvorgängen stattfinden, mikroskopisch zu beobachten und zu quantifizieren. Die ermittelten Kennwerte liegen insbesondere für die thermischen Größen in dichter Nähe zu experimentellen Daten. Das Spannungs-Dehnungs Verhalten wird qualitativ mit guter Übereinstimmung mit dem realen Verhalten wiedergegeben. Die kurze Zeitskala, auf der sich die Simulationsmodelle befinden, hat jedoch mikromechanisch extremeres Verhalten zur Folge, als makroskopisch beobachtet wird. Durch Erweiterung der Modelle werden biaxiale Verstreckvorgänge, wie sie im Extrusionsblasformprozess beispielsweise während des Aufblasens des Vorformlings auftreten, nachgebildet. Die Betrachtung verschiedener Abkühlbedingungen, insbesondere unter Formzwang, ist in Anlehnung an den Realprozess weiterer Schwerpunkt der Untersuchungen. Die Analyse der biaxial verstreckten Modelle offenbart, dass Entschlaufungsvorgänge während des Verstreckens die weitere Entwicklung der Polymersysteme dominieren. Es gelingt, die Dynamik von Kristallisationsvorgängen in Abhängigkeit von Verstreckgrad und Abkühlbedingungen durch unterschiedliche Größen (Verteilung von Verschlaufungspunkten, lokale Orientierungen) zu quantifizieren. Die erzielten Resultate zeigen auf, dass es mittels vergröberten Molekulardynamik Simulationen möglich ist, das mikromechanische Verständnis von Vorgängen, die bei der Verarbeitung von Kunststoffen auftreten, signifikant zu erweitern. During the development phase of plastic components, simulations are being used to an increasing extent. Against the background of product requirements and the inevitable necessity of conserving resources, the expanded use of simulation tools is an essential part of the solution. Among available methods, but so far underutilized with respect to real-life processes, is the molecular dynamics simulation. By the use of this method it is possible to visualize the physical processes occurring on the microscopic level, as e.g. those that arise during plastics processing. This thesis examines how boundary conditions, which mimic the extrusion blow molding process, affect the behavior of polyethylene on the microscopic level. A mesoscopic model (coarse-graining) is applied to describe the polymer. Initially, this model is verified by determining material properties. The uniaxial tensile test is modeled on the micro-scale to identify parameters such as the elastic modulus, yield stress, and Poisson’s ratio. Additionally, thermal properties, particularly those characterizing the crystallization behavior, are identified. The objective of these investigations is the microscopic observation and quantification of effects that occur during dynamic stretching and crystallization processes. The calculated properties show good agreement with the experimental data, especially regarding the thermal parameters. Qualitatively, the stress-strain behavior is reproduced in alignment with experimentally observed results. However, the short time scale of the simulation models leads to micromechanical behavior that is more extreme than what is monitored on a macroscopic level. By extending the simulation models, biaxial stretching processes are simulated. These stretching processes resemble the situation during the inflation of the parison in the extrusion blow molding process. The examination of various cooling conditions, particularly by the use of mold constraints, is another focus of the investigations. The analysis of the biaxially stretched simulations reveals that disentanglement processes during stretching dominate the further development of polymer systems. It is possible to quantify the dynamics of crystallization processes depending on the degree of stretching and cooling conditions through various parameters (distribution of entanglement points, local orientations). The results indicate that coarse-grained molecular dynamics simulations are able to significantly enhance the micromechanical understanding of local events occurring during plastic processing.

Energy meteorology is an applied research field of meteorology that focuses on the study and prediction of weather conditions and events that affect energy production and use. This field has become increasingly important as the energy industry has become more dependent on weather conditions, especially in the areas of renewable energy sources such as wind energy, solar energy, and hydropower. The following paper has been written by experts of the Committee on Energy Meteorology of the German Meteorological Society summarizing their more than 30 years of experience and lessons learnt. It gives an overview of activities in energy meteorology that are already essential for the transformation of energy systems to systems with high shares of renewable energies. Building on this, the experts have created a vision of future topics that describe the future research landscape of energy meteorology. The authors explain that work in energy meteorology in recent years has primarily been concerned with the physically based modeling of wind and solar power generation and the development of short-term forecasting systems. In future years, a significant expansion of work in the areas of energy system modeling, digitalization, and climate change is expected. This includes the detailed consideration of regionally specified spatiotemporal variability for system design, the integration of artificial intelligence skills, the development of weather-related consumption based on smart meters, and the mapping of the effects of climate change on the energy system in planning and operating processes.

Lattice Boltzmann method (LBM) simulations of incompressible flows are nowadays common and well-established. However, for compressible turbulent flows with strong variable density and intrinsic compressibility effects, results are relatively scarce. Only recently, progress was made regarding compressible LBM, usually applied to simple one and two-dimensional test cases due to the increased computational expense. The recently developed semi-Lagrangian lattice Boltzmann method (SLLBM) is capable of simulating two- and three-dimensional viscous compressible flows. This paper presents bounce-back, thermal, inlet, and outlet boundary conditions new to the method and their application to problems including heated or cooled walls, often required for supersonic flow cases. Using these boundary conditions, the SLLBM's capabilities are demonstrated in various test cases, including a supersonic 2D NACA-0012 airfoil, flow around a 3D sphere, and, to the best of our knowledge, for the first time, the 3D simulation of a supersonic turbulent channel flow at a bulk Mach number of Ma=1.5 and a 3D temporal supersonic compressible mixing layer at convective Mach numbers ranging from Ma=0.3 to Ma=1.2. The results show that the compressible SLLBM is able to adequately capture intrinsic and variable density compressibility effects.

In welchem Zusammenhang steht ›das Virtuelle‹ mit Poetiken, die in der Romantik konturiert wurden? Andreas Sieß zeigt, dass sich die ästhetischen Vorstellungen dessen, was ›das Virtuelle‹ ist, nicht nur bereits um 1800 konsolidierten, sondern dass die (bild-)ästhetischen Maßstäbe, die heute grundlegend für moderne Anwendungen der Virtual Reality sind, bereits damals Gegenstand von Aushandlungen waren. Anhand der Begriffe ›Maschine‹ und ›Atmosphäre‹ verhandelt er zwei gegenläufige Stoßrichtungen des Virtuellen, deren dialektisches Spiel eine neue Perspektive auf Fragestellungen zu der Gestaltung von gegenwärtigen virtuellen Medien anbietet.

A novel multidimensional index modulation-based differential chaos shift keying (DCSK) technique, designated as Joint Subcarrier Time Reference Index Modulation-aided Differential Chaos Shift Keying (JSTRIM-DCSK), is proposed for efficient data transmission in chaotic communication systems. The JSTRIM-DCSK system integrates subcarrier, time slot, and reference signal indexing to transmit information and offers two variants: JSTRIM-DCSK-I and JSTRIM-DCSK-II. The data is organized into L subblocks, each containing Ns subcarrier index bits ps and Nt time slot index bits pt , reference index bits pr , and modulated bits pm . The subcarrier and time slot index bits jointly select an active or inactive subcarrier time slot combination from a total of Ns ⋅ Nt possibilities, categorizing the system as either JSTRIM-DCSK-I (active) or JSTRIM-DCSK-II (inactive). The reference indexed bits select a single chaotic reference signal from Nr orthogonal chaotic vectors generated using the Gram-Schmidt orthogonalization process. The modulated bits are transmitted using a DCSK modulation scheme. Analytical expressions for the bit error rate (BER) performance of the JSTRIM-DCSK system are derived under both additive white Gaussian noise (AWGN) and multipath Rayleigh fading channel (MRFC) conditions. Furthermore, the potential for energy savings, bandwidth efficiency, and system complexity of the JSTRIM-DCSK system are thoroughly analyzed and compared with those of the existing techniques. The simulation results validate the analytical expressions and demonstrate the potential of JSTRIM-DCSK to achieve high data rates, efficient energy savings, and a competitive BER performance.

Art installations that engage in a dialogical relationship with their surrounding environment, transcending the confines of an isolated existence, demand a nuanced articulation of the dynamic interplay among the artwork, the spatial context, and the observer. The following report endeavors to delineate and investigate the central elements of reception and the aesthetic of production pivotal to the media art installation ‘Skopéin’, exhibited at the Evangelische Stadtkirche Karlsruhe during the late summer of 2022, through the lens of ethnographic introspection (‘autoethnography’). Given that the authors of this discourse are concurrently the creators of the aforementioned installation, the following text serves as an exploratory analysis into the fabrication process of a media art installation, employing anthropological methods.

‘Communication’ is the basic concept of an aesthetic media theory and, under the title ‘communication aesthetics’, is particularly suitable for defining a capacity of that phenomenon that also describes a holistic experience of so-called digitality in a new way. In the passage through this concept of communication, ‘communication aesthetics’ is therefore also the basic term for studies of digital media cultures and is used here as an example to determine the relevant phenomena of mediality, materiality and the contemporary technological body practices associated with them. ‘Aesthetics of communication’ is then also the title word for the sought-after answer to the question of whether the speech of transfer between different arts as ekphrastic representation acquires a significance of its own that cannot be decomposed by unconditionally necessary and, as a rule, even more important reflection on its effects. The essay examines how both sides of the term – the ‘aesthetic’ and the ‘communicative’ – can be discussed in order to reflect on their connection, especially against the background of the implications of the digital per se. In the first part, the contrasts that determine this conceptual construction are analyzed using an example of media culture in order to read them as the basic definitions of a dialectical concept of the ‘communicative-aesthetic’. Against this background, the second part of the essay deals with the related ‘communication-aesthetic’ practices that could be used as the ingredients and objects of a genuine interdisciplinary media theory.

This study examines the impact of integrating solar photovoltaic (PV) systems on power factor (PF) within low-voltage radial distribution networks, using empirical data from the Energy Self-Sufficiency for Health Facilities in Ghana (EnerSHelF) project sites in Ghana. The research included simulations focusing on optimal PV integration, with and without PF considerations, and the strategic placement of PV and shunt capacitors (SC). Three scenarios evaluated PV injection at high-load demand nodes, achieving penetration levels of 85.00 percent, 82.88 percent with high voltage drop, and 100.00 percent with high loss nodes. Additionally, three scenarios assessed SC allocation methods: proportional to the node's reactive power demand (Scenario I), even distribution (Scenario II), and proportional to installed PV capacity at PV nodes (Scenario III). The analysis used a twin-objective index (TOI), combining voltage deviations and power factor degradation. Results showed significant PV curtailment was necessary to achieve standard PF. Optimal penetration levels, considering TOI, reduced PV penetration from 85.00 percent to 63.75 percent, 82.88 percent to 57.38 percent, and 100.00 percent to 72.50 percent for high load, high voltage drops, and high loss nodes, respectively. Notably, all scenarios showed a concerning PF of 0.00 at dead-end nodes (P20, P21, P22). Scenario I achieved PF ranges of -0.26 to 1.00 with PV at high load, -0.69 to 1.00 with PV at high voltage drop, and 0.95 to 1.00 with PV at high loss nodes. Scenario II produced similar ranges, -0.48 to 1.00, -1.00 to 0.99, and 0.30 to 0.96, with PV placement at high load, voltage drops, and loss nodes, respectively. Scenario III yielded ranges of -0.19 to 0.97 (high load), -0.23 to 1.00 (high voltage drop), and 0.86 to 0.96 (high losses). The study concluded that the most effective strategy involves installing PVs at high-loss nodes and distributing SCs proportionally to the node's reactive power demand (Scenario I). This approach achieved a more uniform PF pattern throughout the network, highlighting the practical implications of strategic PV placement and targeted reactive power compensation for maintaining a healthy and efficient distribution system with solar PV integration.

The recent transformation of the energy sector brings new challenges in areas such as supply security, efficiency, and reliability. Especially the increase of decentralized power plants leads to a more complex energy system and an increasing complexity. This requires expansion and digitization of the power grid as well as an initiative-taking operation of the grid operator. To investigate such complex systems and its phenomena, modern development methods such as real-time simulation or digital twins (DT) can be used. In this approach a digital replica of the real-world system, a grid section, is developed, which can represent or predict the behavior of the real distribution grid. For this, a model of the real-world system is derived and implemented in a co-simulation environment, in which it receives data via an analyzer or measurement system from the grid model. This paper focuses on the development of the digital twin of a testing grid and a grid analyzer for the measurement. With the digital twin of the testing grid, a first approach is achieved in a real-time capable environment showing the functionalities and interactions of a digital twin. Subsequently the development of the digital twin model is explained, and the results are discussed.

Im neuen IHK-Zertifikatslehrgang „Ausbildung trifft Nachhaltigkeit“ erwerben die Teilnehmenden aus kaufmännischen Berufen umfangreiches Handlungswissen, das sie direkt im betrieblichen Alltag umsetzen können. Damit sind Ausbildende in der Lage, ein kompetenzorientiertes Nachhaltigkeitsprojekt zu konzipieren und es mit ihren Auszubildenden im Betrieb umzusetzen. Der modulare Lehrgang orientiert sich inhaltlich am Deutschen Nachhaltigkeitskodex (DNK). Ausbildende Fachkräfte sollen zudem für die neuen Standardberufsbildpositionen sensibilisiert werden. Nach erfolgreichem Abschluss können die Teilnehmenden das IHK-Zertifikat „Fachkraft Ausbildung für nachhaltige Entwicklung“ erhalten. Im Beitrag werden Chancen und Herausforderungen für den Transfer der Weiterbildung in die Strukturen der Bildungslandschaft der Industrie- und Handelskammern (IHK) erläutert.