FASaN - Fahrerassistenzsysteme adaptive Nachhaltigkeit im Bahnbetrieb

Die Verbesserung und Vernetzung von Fahrerassistenzsystemen hat das Potential, den Bahnverkehr auch langfristig attraktiv und umwelteffizient zu gestalten. Neben der Optimierung einer einzelnen Zugfahrt können zukünftig auch betriebliche Randbedingungen wie Interaktionen mit anderen Zügen, Verspätungen, Vermeidung von Lastspitzen oder hohes Fahrgastaufkommen stärker berücksichtigt werden

Erweiterung von Fahrerassistenzsystemen im Bahnbereich durch die Verbesserung der Datengrundlage (FAS-D)

Das vorliegende Dokument soll als Vorstudie die Machbarkeit einer Erweiterung von FAS hin zu einer Vernetzung der Systeme auf Basis einer verbesserten Datengrundlage aufzeigen. Hierfür wird zunächst die Funktionsweise bestehender Systeme analysiert, der benötigte Da-teninput zusammengefasst und mit dem Fachwissen von Entwicklern und Anwendern abge-glichen. Dabei sollen sowohl die Vorteile der bekannten Systeme berücksichtigt als auch Ver-besserungen identifiziert werden. Für die Verbesserung der Funktionsweise bestehender Sys-teme sowie eine Erweiterung auf vFAS ist es notwendig, die vorliegende Datengrundlage zu überprüfen und zu erweitern

The OpenMolcas Web: A Community-Driven Approach to Advancing Computational Chemistry

The developments of the open-source OpenMolcas chemistry software environment since spring 2020 are described, with a focus on novel functionalities accessible in the stable branch of the package or via interfaces with other packages. These developments span a wide range of topics in computational chemistry and are presented in thematic sections: electronic structure theory, electronic spectroscopy simulations, analytic gradients and molecular structure optimizations, ab initio molecular dynamics, and other new features. This report offers an overview of the chemical phenomena and processes OpenMolcas can address, while showing that OpenMolcas is an attractive platform for state-of-the-art atomistic computer simulations

Chemoton 2.0: Autonomous Exploration of Chemical Reaction Networks

Fueled by advances in hardware and algorithm design, large-scale automated explorations of chemical reaction space have become possible. Here, we present our approach to an open-source, extensible framework for explorations of chemical reaction mechanisms based on the first-principles of quantum mechanics. It is intended to facilitate reaction network explorations for diverse chemical problems with a wide range of goals such as mechanism elucidation, reaction path optimization, retrosynthetic path validation, reagent design, and microkinetic modeling. The stringent first-principles basis of all algorithms in our framework is key for the general applicability that avoids any restrictions to specific chemical systems. Such an agile framework requires multiple specialized software components of which we present three modules in this work. The key module, Chemoton, drives the exploration of reaction networks. For the exploration itself, we introduce two new algorithms for elementary-step searches that are based on Newton trajectories. The performance of these algorithms is assessed for a variety of reactions characterized by a broad chemical diversity in terms of bonding patterns and chemical elements. Chemoton successfully recovers the vast majority of these. We provide the resulting data, including large numbers of reactions that were not included in our reference set, to be used as a starting point for further explorations and for future reference.ISSN:1549-9618ISSN:1549-962

Solvation Free Energies in Subsystem Density Functional Theory

For many chemical processes the accurate description of solvent effects are vitally important. Here, we describe a hybrid ansatz for the explicit quantum mechanical description of solute-solvent and solvent-solvent interactions based on subsystem density functional theory and continuum solvation schemes. Since explicit solvent molecules may compromise the scalability of the model and transferability of the predicted solvent effect, we aim to retain both, for different solutes as well as for different solvents. The key for the transferability is the consistent subsystem decomposition of solute and solvent. The key for the scalability is the performance of subsystem DFT for increasing numbers of subsystems. We investigate molecular dynamics and stationary point sampling of solvent configurations and compare the resulting (Gibbs) free energies to experiment and theoretical methods. We can show that with our hybrid model reaction barriers and reaction energies are accurately reproduced compared to experimental data.ISSN:1549-9618ISSN:1549-962

Quantum chemical data generation as fill-in for reliability enhancement of machine-learning reaction and retrosynthesis planning

Data-driven synthesis planning has seen remarkable successes in recent years by virtue of modern approaches of artificial intelligence that efficiently exploit vast databases with experimental data on chemical reactions. However, this success story is intimately connected to the availability of existing experimental data. It may well occur in retrosynthetic and synthesis design tasks that predictions in individual steps of a reaction cascade are affected by large uncertainties. In such cases, it will, in general, not be easily possible to provide missing data from autonomously conducted experiments on demand. However, first-principles calculations can, in principle, provide missing data to enhance the confidence of an individual prediction or for model retraining. Here, we demonstrate the feasibility of such an ansatz and examine resource requirements for conducting autonomous first-principles calculations on demand.ISSN:2635-098

Evaluating Today's Landscape Multifunctionality and Providing an Alternative Future: A Normative Scenario Approach

Intensive agriculture has had multiple negative effects on the environment across large areas of Europe, including a decrease in the degree to which these landscapes serve multiple functions. A quantitative evaluation of the deficits in landscape multifunctionality is difficult, however, for a given landscape as long as "multifunctional reference landscapes" are lacking. We present an interdisciplinary normative scenario approach to overcome this obstacle. Given the example of the lower Wetter-catchment in the Wetterau region (Hesse, Germany), we compare the existing landscape with an expert-generated multifunctional landscape scenario that may also serve as an alternative future. This approach may inspire policy makers and land users by providing a methodology for the design of alternative multifunctional futures in five steps: (1) documentation of today's landscape structure and land use at the scale of uniformly managed land units; (2) detection of functional deficits of today's landscape considering environmental (soil contamination, groundwater production, water quality, biodiversity), economic (land rent), and societal (landscape perception by its population) attributes; (3) compilation of a catalogue of alternative land uses (including linear landscape elements) suitable to minimize the detected functional deficits; (4) rule-based modification of today's land-use pattern into a normative scenario; and (5) comparison of today's landscape and the normative scenario by applying the model network ITE²M. Results highlight a strongly unbalanced allocation of private and public goods in today's landscape with severe deficits in environmental and societal landscape features, but a significantly higher land rent. The designed multifunctional scenario, instead, may be preferred by the local population, and their willingness to pay for multifunctionality could potentially compensate calculated opportunity costs. Hence, the generated landscape scenario may be regarded as an alternative, multifunctional future

Understanding unusual element-element bond formation and activation: general discussion

International audienc

Computational and theoretical approaches for mechanistic understanding: general discussion

status: publishe