650 research outputs found
Proceedings of SIRM 2023 - The 15th European Conference on Rotordynamics
It was our great honor and pleasure to host the SIRM Conference after 2003 and 2011 for the third time in Darmstadt. Rotordynamics covers a huge variety of different applications and challenges which are all in the scope of this conference. The conference was opened with a keynote lecture given by Rainer Nordmann, one of the three founders of SIRM “Schwingungen in rotierenden Maschinen”. In total 53 papers passed our strict review process and were presented. This impressively shows that rotordynamics is relevant as ever. These contributions cover a very wide spectrum of session topics: fluid bearings and seals; air foil bearings; magnetic bearings; rotor blade interaction; rotor fluid interactions; unbalance and balancing; vibrations in turbomachines; vibration control; instability; electrical machines; monitoring, identification and diagnosis; advanced numerical tools and nonlinearities as well as general rotordynamics. The international character of the conference has been significantly enhanced by the Scientific Board since the 14th SIRM resulting on one hand in an expanded Scientific Committee which meanwhile consists of 31 members from 13 different European countries and on the other hand in the new name “European Conference on Rotordynamics”. This new international profile has also been
emphasized by participants of the 15th SIRM coming from 17 different countries out of three continents. We experienced a vital discussion and dialogue between industry and academia at the conference where roughly one third of the papers were presented by industry and two thirds by academia being an excellent basis to follow a bidirectional transfer what we call xchange at Technical University of Darmstadt. At this point we also want to give our special thanks to the eleven industry sponsors for their great support of the conference. On behalf of the Darmstadt Local Committee I welcome you to read the papers of the 15th SIRM giving you further insight into the topics and presentations
The interactions between gold nanoparticles and their self-assembly
Gold nanoparticles (AuNPs) are one of the most promising building blocks to fabricate versatile nanostructures. Such nanostructures have the great potential to enable new gold-based nanomaterials or nanocomposites with specific properties by precisely controlling the interactions (potential energies and/or forces) between them. In other words, the interactions between AuNPs are therefore regarded as one of the key factors governing particles’ self-assembly process that can drive multiple AuNPs to form ordered structures as required. Quantifying the interactions between them and understanding of their self-assembly process are of great importance and yet still challenging. In this study, molecular dynamics (MD) simulations are performed to calculate the interactions (e.g., potential energies) between AuNPs. The MD results reveal that a more effective force model between AuNPs can be developed as a function of their surface separation compared with the conventional Hamaker equation. In addition, MD simulations examine several effects (i.e., particle size, shape, rotation, surface patch, surfactant, as well as configuration) on their interactions. The results demonstrate that the different impacts of these factors (e.g., the hindrance of surfactant). Apart from spherical gold nanoparticles, interactions between gold nanorods (AuNRs) are also be quantified by MD simulations. The interparticle forces of AuNRs can be expressed as a function of their surface separation and the rotation angle since the rotational movement is applied on AuNR. Further, the MD-derived interparticle force models of gold nanospheres are integrated into discrete element method (DEM) to explore their self-assembly process. To the best of our knowledge, this might be the first time that the MD-based interparticle force models are integrated into DEM to explore the self-assembly process of gold nanoparticles. The results show that ordered nanostructures are ultimately constructed. Specifically, the mean coordination number (CN) of AuNPs (3 nm in size) is up to 5.99 and two major large clusters is observed under the simulation conditions at the equilibrated state. The completion of this study not only allows us to evaluate the interactions between AuNPs by MD simulation, but profoundly, the MD-DEM coupling approach opens a new window to unfold the self-assembly process of AuNPs
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An Experimental and Numerical Assessment of Ejected Martian Biosignatures Impacting Phobos
Phobos, the larger and closer of Mars’ two moons, is not considered a location where extant or extinct life may exist. However, its close proximity to Mars means it could be a repository for impact-ejected material that may contain evidence of ancient martian life.
This thesis investigates the delivery of possible martian biosignatures to Phobos and their subsequent detection within the Phobos regolith. iSALE-2D hydrocode was used to investigate the conditions experienced by Mars-like projectiles impacting Phobos-like targets, that were then compared with a survival criteria of shock pressure and temperature for amino acids. The resultant amino acid survivability varied broadly. To validate the numerical simulations, hypervelocity impact experiments were conducted, whereby bespoke Mars-relevant basaltic projectiles doped with the potential organic biosignature glycine, were fired using the All-Axis Light Gas Gun (AALGG) into two Phobos regolith simulants at a range of velocities. The bespoke projectiles fragmented upon acceleration resulting in buckshot cluster impacts where the proportion of glycine that survived impacts at similar velocities varied broadly, regardless of Phobos simulant used. This presented a fundamentally different impact process than would be experienced on Phobos. Therefore, to validate the numerical simulations with an alternative approach, the impact experiment results were compared to numerical simulations on the spatial scale of the AALGG experiments, that focussed on cluster impacts. These simulations revealed that amino acid survival and detection could be significantly affected by how early within a cluster a projectile fragment impacts. Nevertheless, the small-scale numerical simulations aligned well with the impact experiments suggesting it is an adequate tool for estimating the temperatures and pressures in real impactors. Finally, comparing the results from the large-scale numerical simulations with the impact experiments it was revealed that the datasets could be fit by logistic function sigmoid curves with impact velocity.
This study highlights the stochastic nature of impact delivery, considers how some aspects of cluster impacts of martian ejecta on Phobos may result in resolvable biosignature survival, and provides a baseline from which more complex molecular biosignature survival and modification could be investigated. It supports the potential presence of martian material, including biosignatures, within Phobos’ regolith, which is significant for interpreting data from samples returned from Phobos by JAXA’s Martian Moons eXploration mission
Data journeys in the sciences
This is the final version. Available from Springer via the DOI in this record. This groundbreaking, open access volume analyses and compares data practices across several fields through the analysis of specific cases of data journeys. It brings together leading scholars in the philosophy, history and social studies of science to achieve two goals: tracking the travel of data across different spaces, times and domains of research practice; and documenting how such journeys affect the use of data as evidence and the knowledge being produced. The volume captures the opportunities, challenges and concerns involved in making data move from the sites in which they are originally produced to sites where they can be integrated with other data, analysed and re-used for a variety of purposes. The in-depth study of data journeys provides the necessary ground to examine disciplinary, geographical and historical differences and similarities in data management, processing and interpretation, thus identifying the key conditions of possibility for the widespread data sharing associated with Big and Open Data. The chapters are ordered in sections that broadly correspond to different stages of the journeys of data, from their generation to the legitimisation of their use for specific purposes. Additionally, the preface to the volume provides a variety of alternative “roadmaps” aimed to serve the different interests and entry points of readers; and the introduction provides a substantive overview of what data journeys can teach about the methods and epistemology of research.European CommissionAustralian Research CouncilAlan Turing Institut
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