KITopen
Not a member yet
63711 research outputs found
Sort by
AlphaFL: Secure Aggregation with Malicious2 Security for Federated Learning against Dishonest Majority
No full textBRIDGE German-Chilean Institute for Element Extraction from Brines and Integrated Geological Reservoir Modeling
No full textChallenges and Strategic Choices in Business Model Evolution of European Digital Health Startups: A Qualitative Study
No full textStartups are crucial in driving digital transformation in healthcare, with business modeling being essential for their success. However, these digital health startups face challenges in the healthcare sector, including stringent regulations and multiple stakeholders. As a result, they must make unique business model choices. This study investigates the challenges of digital health startups and systematically maps the resulting business model choices in the European Union. Through 32 expert interviews with founders and leaders, the study identifies key challenges and develops a catalog of business model choices across critical dimensions: value proposition and customer segments, medical device and regulatory compliance, evidence generation and clinical studies, revenue model and cost structure, key resources and funding, and key partnerships and customer engagement. Medical device regulations were identified as the major barrier for many startups, followed by related challenges regarding revenue models and funding. The findings emphasize the importance of addressing medical device regulatory requirements early in the business model design process and adapting related components such as funding or revenue models. The study further generalizes these insights into a conceptual model of the temporal evolution of digital health startup business models. This work contributes to the ongoing discussion on sustainable business models in digital health and provides a catalog of business model choices for digital health startups
Dehydrogenation of methanol to formaldehyde using sodium-based catalysts on a mini-plant scale
No full textFormaldehyde, an important chemical precursor in many industrial processes, is produced by various methods, each with their own efficiency and challenges. The presented thesis provides an in-depth investigation of the gas-phase dehydrogenation of methanol to formaldehyde, focusing on the potential of sodium compounds, particularly sodium and sodium carbonate, as catalysts. Furthermore, it presents the state of the art in formaldehyde production, highlighting the need for innovative approaches to meet growing industrial demands and increased environmental concerns. A specially designed and constructed experimental setup, the MEDENA mini-plant, is at the center of this thesis, allowing reaction tests to be carried out and providing important insights into the behavior of substrates, products, and catalysts. Sodium metal and sodium carbonate were studied as catalysts for the direct dehydrogenation of methanol to formaldehyde. Additionally, particular attention was given to the evaluation of the sodium dosing system. The results indicated that sodium vapor can be dosed continuously while at the same time, obtaining high formaldehyde and hydrogen yields. Moreover, a novel heating method for the dehydrogenation of methanol to formaldehyde was examined. Unlike traditional heating techniques, which often employ indirect or convective heat transfer, direct resistance heating applies electrical current through the catalyst body. This direct approach ensures rapid and uniform heating, minimizing potential heat losses and ensuring the most favorable reaction conditions. Due to its efficiency, the direct resistance heating concept has the potential to transform conventional methods of formaldehyde production, offering both economic and environmental benefits. In summary, this research aimed to improve formaldehyde production techniques by bridging the gap between conventional routes and newly developed approaches. This work paves the way for environmentally friendly, efficient and sustainable formaldehyde production, thereby preparing the ground for future industrial applications
A new versatile dropsonde for atmospheric soundings – the KITsonde
No full textA new modular multi-sensor aerological dropsonde system for high and fast-flying research aircraft has been developed for studying atmospheric processes. This new system allows us to drop release containers with up to four sondes inside, and data from up to 30 sondes can be transmitted simultaneously. After separation from the release container, the sondes enable high-resolution spatio-temporal profiling of temperature, humidity, and pressure with a time resolution of 1.12 s and wind of 1 s, corresponding to approximately 10 m vertical resolution. The modular design ensures simple integration of additional sensors without extensive flight tests and recertification for e.g. particle measurements and radioactivity.
The standard meteorological sonde comprises sensor elements of a commercial Graw DFM-17 radiosonde, a 400 to 406 MHz band communication link to the aircraft, and an optional satellite communication module. By means of the satellite link, the data can be made available worldwide in near-real time, and data loss is avoided when the dropping aircraft leaves the telemetry range.
The main feature of the new system is the release container, which allows for dropping through standard dropsonde dispensers of both mid-size turbo-prop aircraft (e.g. Dornier Do 128-6) and jet aircraft (e.g. the Gulfstream 550 “High Altitude and Long Range Research Aircraft” HALO). The release container ensures safe separation from the aircraft and protects its payload during deceleration from aircraft speed to fall speed before the sondes are released by an electro-mechanical mechanism. Operations in different campaigns have confirmed the reliability of the entire system and the quality of acquired data. Feasibility of the technical and operational approach for targeted observations of a mesoscale convective system in Argentina was demonstrated by HALO measurements during the SouthTRAC (TRAnsport and Composition of the southern hemisphere UTLS (upper troposphere–lower stratosphere) campaign) campaign. Moreover, a configuration consisting of a meteorological sonde coupled with an optical counter for particle sizing was tested during a Saharan dust episode over Germany using a Dornier Do 128-6 aircraft. Secondly, a meteorological sonde together with a radioactivity sensor was successfully dropped from a Learjet 35A
Complexation of Cm(III) with monosilicic acid in chloride media
No full textIn this work, we present a detailed complexation study of Cm(III) with monosilicic acid in a NaCl medium at low to medium ionic strengths (I = 0.01–3.00 m). The complexation has been monitored using time-resolved laser fluorescence spectroscopy (TRLFS) in the pH range of 4–6. The results show that the formation of the monosilicate complex, [Cm(HSiO)], is decreased with increasing ionic strength, leading to vast changes in the complex stability constant. Using the Specific Ion Interaction Theory (SIT), we were able to determine the complex stability constant at ionic strength Im = 0 with log K = 8.1 ± 0.8 and the binary ion-ion interaction coefficient ε ([Cm(HSiO)],Cl) = 0.40 ± 0.04. Additionally, we studied the complexation at elevated temperatures at low to medium ionic strength. Using the van’t Hoff equation, Δr H = 16.4 ± 0.5 kJ mol, Δr S = 210 ± 21 J K mol and the free Gibbs Energy Δr G = 46.2 ± 5 kJ mol have been determined. These results show that the complexation reaction is endothermic and driven by an increase of entropy. These novel results obtained in a wide range of various ionic strengths are very important for the modeling of actinide behavior under near-field conditions of a nuclear waste repository in clay formations containing pore and formation waters with increased ionic strength
ROCK: A Flexible Gyrotron Cavity Simulation Toolkit Using an Accuracy-Improved Time-Dependent Self-Consistent Multimode Interaction Model
No full textRelativistic oscillator calculation kit (ROCK) is a self-consistent time-dependent multimode multi-harmonic code recently developed at KIT to simulate the interaction between electrons and microwaves in gyrotron cavities. Its key features include a flexible software design, the use of the finite element method, the capability for precisely resolving the electron motion, and an enhanced formulation of field excitation. The last two features are essential model differences and are discussed in detail. Preliminary simulation comparisons demonstrate the validity and highlight the potential advantages of the improved model implemented in ROCK
Reduction of Selected Road Noise Phenomena by Modifying Suspension Kinematics Using Metamodels in the Digital Vehicle Development Phase
No full textWith growing electrification and comfort in cars, road noise reduction is increasingly important. This study explores influencing road noise via suspension kinematics optimization in early development. 500 kinematics variations are modeled with ANNs for fast numerical and qualitative optimization. Simulations resolve NVH conflicts and guide metamodel-based cavity noise tuning. Hardware validation confirms an effective, cost- and weight-neutral NVH improvement