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An extended artificially thickened flame model for turbulent hydrogen and hydrogen-enriched flames with intrinsic instabilities under gas turbine relevant conditions
No full textHydrogen and hydrogen blends with ammonia or natural gas are cornerstones in the transition to future environmentally friendly energy systems, such as gas turbines and aero-engines. However, hydrogen's unique characteristics lead to intrinsic flame instabilities, resulting in an up to sixfold increase in turbulent flame speeds under gas turbine-relevant conditions compared to flames without instabilities. These effects are not captured by current combustion models, presenting a major barrier for computational fluid dynamics (CFD) simulations. This study addresses these limitations by developing an extension to the widely used artificially thickened flame (ATF) model, validating it for wide operating conditions and applying it to turbulent configurations. To this extent, over 200 direct numerical simulations (DNS) of laminar planar flames are analyzed, unraveling the characteristics of the enhanced flame speed. The subsequently developed model is validated across comprehensive variations in pressure (1 atm−20 atm), temperature (300 K−700 K), equivalence ratios (Φ=0.4−1.0), and fuel compositions (pure H2, precracked ammonia (NH3/H2/N2) and hydrogen natural gas blends (CH4/H2)) to ensure the model's applicability for technically relevant operating conditions. Additionally, the model is transferred to turbulent conditions using Large Eddy Simulations. For model validation, multiple high-fidelity DNS of turbulent jet flames at various conditions are performed. The advanced model shows excellent agreement in a laminar configuration and significant improvements in predicting turbulent flame speeds of the turbulent jet flames compared to the state-of-the-art model. By enhancing the widely used ATF model to account for hydrogen characteristics, this study supports the further development of efficient and environmentally friendly hydrogen-powered energy systems
Benchtop NMR for catalytic hydrogenation reactions suitable for studies with parahydrogen
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Tuning supported Fe-Ag catalysts for selective acetylene hydrogenation: a combined experimental and computational study
No full textHybrid Downlink Beamforming with Outage Constraints under Imperfect CSI using Model-Driven Deep Learning
No full textNewsRECON: News article REtrieval for image CONtextualization
No full textIdentifying when and where a news image was taken is crucial for journalists and forensic experts to produce credible stories and debunk misinformation. While many existing methods rely on reverse image search (RIS) engines, these tools often fail to return results, thereby limiting their practical applicability. In this work, we address the challenging scenario where RIS evidence is unavailable. We introduce NewsRECON, a method that links images to relevant news articles to infer their date and location from article metadata. NewsRECON leverages a corpus of over 90,000 articles and integrates: (1) a bi-encoder for retrieving event-relevant articles; (2) two cross-encoders for reranking articles by location and event consistency. Experiments on the TARA and 5Pils-OOC show that NewsRECON outperforms prior work and can be combined with a multimodal large language model to achieve new SOTA results in the absence of RIS evidence. We make our code available
Unmasking digital threats in the pursuit of human rights and environmental defense in La Guajira, North Colombia
No full textThose engaged in the defense of human and land rights, particularly in areas of resource extraction, are increasingly exposed to violence, including a growing number of digital threats. In Colombia, the legacy of decades of armed conflict has overshadowed concerns regarding digital rights, resulting in reports of digital surveillance and online harassment without the requisite judicial oversight. Due to the paucity of research on this topic, this study examines the experiences of 37 environmental and human rights defenders (EHRDs) in La Guajira, North Colombia, who are leveraging information and communication technologies (ICTs) to amplify their concerns in an extractivist region with a history of human rights abuses. The findings indicate a significant prevalence of technology-facilitated violence (TFV) against EHRDs, including death threats, hacking, and hate speech through various digital channels. The spectrum of threats is attributed to several sources, including armed groups, multinational companies, and individuals within the affected communities. The study emphasizes the necessity of adopting a comprehensive approach to violence, integrating TFV into a more expansive conceptualization of violence. Failing to acknowledge the prevalence of TFV may result in an incomplete understanding of the experiences of EHRDs and the consequences of such violence, including self-censorship and emotional harm. Given the increasing overlap between digital and physical violence, we present a framework to enhance the capture and understanding of TFV. Furthermore, this study demonstrates the shortcomings of current security protocols in addressing the multifaceted violence directed at EHRDs due to their opposition to extractive agendas
What is a biosensor? A terminological guide from biomolecular recognition to bioindicators
No full textBiosensors are an integral part of modern medicine, are used in basic research, and are increasingly used by consumers as point-of-care and wearable devices. Meanwhile, the underlying technological approaches are rapidly expanding, including spectroscopic sensing, artificial bioreceptors, synthetic biological approaches, whole-cell biosensors, and artificial intelligence. With these diversifications in applications as well as technology, the scope and meaning of the term biosensor is blurring. This paper attempts to give an overview of the sensing approaches, with their physical, chemical, biochemical, and biological principles, and an overview of the fields of application, including nonliving systems and living systems. This leads to a comprehensive overview and a reappreciation of the term biosensor, including not only devices with a molecular biorecognition element and physico-chemical readout but also the sensing of living biological systems using physical and chemical methods, and the use of living biological systems for sensing purposes