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Potential of Sorption-Enhanced Ammonia Synthesis - An Equilibrium and Reactor Modeling Study
No full text140153Ammonia production is one of the most important industrial chemical processes, but the synthesis reaction is strongly limited by chemical equilibrium. This is commonly compensated by applying high pressures, but large recycle ratios and purging losses are still unavoidable. Equilibrium limitations can alternatively be evaded by sorption enhancement, where NH3 is selectively removed from the reaction mixture by a solid sorbent material. One material class commonly applied in this approach are metal halides like MgCl2, as they typically show high NH3 capacity even at elevated temperatures. In this study, a thermodynamic equilibrium model based on Gibbs energy minimization is established that is able to predict the simultaneous NH3 synthesis and sorption equilibrium. After parametrization for metal chloride-based sorbents, the model is used to estimate the potential effect of sorption enhancement on the NH3 synthesis in equilibrium. For kinetic studies under realistic operating conditions, a reactor model was established using kinetics for both iron and ruthenium-based catalysts. Simulations reveal that near-full conversion is possible in sorption-enhanced NH3 synthesis under a wide range of realistic operating conditions. At thermodynamically unfavorable conditions, the process benefits from overstoichiometric amounts of sorbent as this keeps the sorbent saturation low and thus increases the sorption driving force. The integration of a sorbent material into the NH3 synthesis reaction was shown to result in increased conversion, but at the same time also allows for a higher NH3 formation rate. An increase in H2 conversion by up to 550% was found at 350 °C, 100 bar, 15,000 h-1 for twice the stoichiometrically required sorbent. While it has been demonstrated experimentally before, these findings quantify and emphasize the vast potential of sorption-enhanced NH3 synthesis under a wide range of conditions.5
Innovative Entrepreneurship as Policy Concern: Geography, Evolution and Antecedents of Policy Mixes
No full textInnovation policies affect the costs of entrepreneurial individuals combining and adapting heterogenous resources in the pursuit of profit. Yet, while studies of the effects of select policies in support of innovative entrepreneurship proliferate, little is known about the combinations of different policies in support of innovative entrepreneurship usually at play in a country. Moreover, what leads policymakers to focus their attention on select types of these policies remains unconsidered. In this paper, we map policy mixes for innovative entrepreneurship and study their variation in relation to entrepreneurial activity. We find that relative to other policies in support of innovation, innovative entrepreneurship policies tend to receive more attention in Europe than in the US. We also find that both innovative entrepreneurial activity and technological entrepreneurial activity are associated with select elements in policy mixes for innovative entrepreneurship. We contribute to the literature on entrepreneurship policy by introducing a “mix perspective” and providing evidence on possible antecedents of entrepreneurship policy choices. We also contribute to the literature on entrepreneurial ecosystems by illuminating the role of policy as a contextual factor for innovative entrepreneurship.2022
Understanding replication environments - a systems research approach to smart city replication of autonomous delivery robots
No full textEuropean policymakers chose the systematic funding of smart city initiatives to incentivize and accelerate innovation and sustainability transitions. To ensure these initiatives’ broader effectiveness, smart city replication has been incorporated in funding calls for research projects as a policy instrument for innovation diffusion, information dissemination and mutual learning. With a growing theoretical and empirical base for these replication activities, there is an increased awareness that integrating and transferring new ideas and solutions into the urban context requires a holistic perspective and includes various endogenous and exogenous influencing factors. This article proposes a systemic view by presenting a method for analysing the replication environment for autonomous delivery robots based on a causal loop diagram. The method is applied conceptually to a district in Munich. The developed approach, which is called Replication Causal Loop Diagram, serves as an analytical tool to generate and provide relevant contextual knowledge and information about the replication environment to facilitate the operational planning and implementation of replicable initiatives, solutions, and practices. In further development steps and in particular settings, the approach can also be a valuable addition to the replication portfolio for stakeholder engagement and consensus building.18
Agile Sub-Terahertz to Terahertz Broadband Time-Domain Photonic Channel Sounder
No full text164169This paper presents the design and implementation of an agile sub-terahertz (sub-THz) broadband time-domain photonic channel sounder, capable of characterizing wireless propagation channels within the 100 GHz to 500 GHz frequency range. The sounder employs a hybrid architecture that combines photonic carrier generation through heterodyne mixing of continuous-wave lasers locked to a frequency comb, along with electronic components for broadband sounding sequence synthesis and digitization. This design enables precise and tunable carrier frequency generation, overcoming the limitations of traditional electronic-only systems. Experimental evaluations highlight the system’s high temporal resolution, phase stability, and broadband performance, including over-the-air calibration and monostatic channel measurements across three sub-THz bands (160 GHz, 300 GHz, and 450 GHz). The results establish the feasibility of the time-domain photonic channel sounder as a powerful and versatile tool for measuring various, widely scattered, and spread sub-THz bands
Applying assurance levels when issuing and verifying credentials using Trust Frameworks
No full text167178Technical interoperability of the issuance, presentation, and verification of verifiable credentials (VC) across domains of trust is a current challenge for self-sovereign identity. We present an approach incorporating different levels of assurance and trust domains in an eIDAS compliant way. This is illustrated through a use case with real-world relevance: the issuance and cross-border usage of the European Health Insurance Card
Thermo-chemical conversion of bio-waste for energy carrier production: A spatial analysis for Bavaria, Germany
No full textThe current global geopolitical situation has brought the matter of energy security and energy gap to the forefront. In addition to that, perceived future sustainable development and decarbonization goals demand increased application and use of renewable energy (RE) sources into the energy system. However, considering the spatial availability of RE source’s potential for generating green electricity (GE) is of paramount importance. Limitations in availability of the RE sources such as wind energy and solar potential over various spatial as well as temporal scale, requires identification of alternative sources of energy generation and storage. In this regard, bio-waste (BW) and sewage sludge (SS) processing in urban as well as rural pockets can be seen as a practical source of energy production. In this paper, an attempt has been made to analyze the spatial impact of BW＋SS processing using ‘Thermo-chemical conversion’ (TCC) technologies such as novel ‘Thermo catalytic reforming’ (TCR®) process developed at Fraunhofer UMSICHT. The idea is to understand the sustainable bio-waste treatment potential using TCR® technology and in turn production of energetically and commercially valuable intermediates from it. In accordance with the ‘Sustainable development goals’ (SDG-7, 13), such approach of BW＋SS treatment can provide affordable, reliable, sustainable, and modern energy for all. In addition to that, production of sustainable/green hydrogen (SH/GH) can also be envisioned while saving considerable number of valuable resources such as water. Bavarian region of Germany has been taken as an area of interest for this study. Cities such as Augsburg, Munich, Neu-Ulm and, Nuremburg are identified to be having highest potential for BW＋SS processing. It has also been found that there is a possibility for regional cluster formation to exploit the BW and SS processing potential.1
Applying self-normalizing neural networks to tackle data-driven soft sensing problems in manufacturing lines
No full text57705773In this paper we present the results of our participation in the IEEE BigData 2021 Cup: Soft Sensing at Scale. The goal of the contest is to classify eleven different tasks based on high-dimensional time series soft sensing data from a wafer manufacturing process. To achieve the classification, two different data-driven soft sensing approaches have been implemented. One approach is especially optimized towards cost and runtime, whereas the other achieves better accuracy but comes at a higher runtime and cost. Both methods can be deployed in the manufacturing line, e.g. a wafer manufacturing factory, by using incremental learning, thus making sure that the models are always up to date in an changing environment with different data distributions. Both models can be integrated for different soft sensing scenarios in a manufacturing line, i.e. the cost-optimized model in a timing-critical scenario and the accuracy-optimized model in a scenario requiring exactly that high accuracy. This guarantees low costs and high accuracy where they are needed
Venomics of the milos viper (Macrovipera schweizeri) unveils patterns of venom composition and exochemistry across blunt-nosed viper venoms
No full textIntroduction: Snakebite is a neglected tropical disease and a globally important driver of death and morbidity. Vipers of the genus Macrovipera (Viperidae: Viperinae) are among the snakes of higher medical importance in the Old World. Despite the medical relevance of Macrovipera venoms, the knowledge regarding them is heterogeneously distributed with virtually all works conducted so far focusing on subspecies of Macrovipera lebetinus, while other species within the genus are largely overlooked. Here we present the first proteomic evaluation of the venom from the Greek endemic Milos viper (Macrovipera schweizeri). In line with clinical symptoms typically elicited by Macrovipera envenomations, Milos viper venom primarily comprises coagulotoxic and cytotoxic protein families, such as metalloproteinases (svMP) and serine proteases (svSP). Methods: We conducted comparative bioactivity assays on venoms from M. schweizeri and the M. lebetinus subspecies M. lebetinus cernovi, M. lebetinus obtusa, and M. lebetinus turanica, and showed that they all exhibit similarities in levels of cytotoxicity proteolytic activity, and inhibition of prokaryotic growth. Lastly, we compared Macrovipera venom profiles by 1D-SDS-PAGE and RP-HPLC, as well as our proteomic data with previously published Macrovipera venom proteomes. Results and discussion: The analyzes performed to reveal that a general venom profile seems to be conserved across blunt-nosed vipers, and that, M. schweizeri envenomations, similarly to those caused by other blunt-nosed vipers, are able to cause significant tissue damage. The present work represents an important starting point for the development of comparative studies across the full taxonomic range of the genus Macrovipera and can potentially help optimize the treatment of envenomations caused by M. schweizeri.1
Optimized Castellated Hole Interconnects for Ceramic-Based Modular Millimeter-Wave Applications Up to 85 GHz
No full textThis paper investigates the application of castellated holes, or Plated Half Holes (PHH), as RF interconnects for modular millimeter-wave designs by integrating them on low-temperature co-fired ceramics (LTCC). This work explores the electromagnetic capabilities of such transitions through a combined approach of full-wave simulation, simplified modeling, and measurement. A key objective was to investigate how much a detailed HFSS model could be simplified, both geometrically and conceptually, while still providing reliable results about the original structure's high-frequency performance. Capacitance values were estimated and calculated from simplified geometries and compared to simulation data. While no precise quantitative agreement is expected or required, the simplified models were sufficient to identify dominant effects, understand design tradeoffs, and guide parameter optimization. Empirical correction factors were introduced to improve correlation and to create a tool for rapid estimation for design optimization. An example LTCC application achieves insertion loss above -0.5 dB up to 85 GHz and above, as confirmed by full-wave simulations. Test structures were designed and fabricated, showing a general proof of concept of manufacturing castellated holes on LTCC technology in the desired geometrical dimensions to ensure efficient hybrid stack-up integration and high-performance RF interconnects