Persistent Identifiers (PIDs) are elementary ingredients in nowadays and future research data management processes. Looking at various data life cycles, identifiers help to achieve certain goals in a very efficient way, supporting steps to find, relate, integrate and publish data. Various identifier systems have been developed for this purpose, which are provided by various providers. This created the challenge of the complex and different methods of using the identifiers. Depending on the system, an identifier can, for example, point to a landing page or directly to a digital object. The PID Metaresolver unifies the use of PIDs from different providers and thus supports and simplifies the use of the referenced object. It is a service for resolving PIDs from various providers, validating the PID provider for a given PID and integrating additional providers. With the PID Metaresolver, workflows and analyses of research data can be extended to a larger list of providers. We present the design and implementation of the PID Metaresolver service and give an insight into the many possible uses.

This paper introduces a newly developed service called MINE. The service assists Digital Humanities scientists in solving two problems: data acquisition and text analysis on a large scale. MINE consists of two main components: a search engine and a workspace. The search engine does not only provide a way to search across various data sources, but also facilitates access to difficult-to-access sources. Meanwhile, the workspace allows users to analyze data using provided models or writing their own analysis workflows. Thanks to this, a new approach to text analysis in Digital Humanities can be taken, which enables large-scale analyses.

The paper gives a brief introduction about the workflow management platform, Flowable, and how it isused for textual-data management. It is relatively new with its first release on 13 October, 2016. Despite theshort time on the market, it seems to be quickly well-noticed with 4.6 thousand stars on GitHub at themoment. The focus of our project is to build a platform for text analysis on a large scale by including manydifferent text resources. Currently, we have successfully connected to four different text resources andobtained more than one million works. Some resources are dynamic, which means that they might add moredata or modify their current data. Therefore, it is necessary to keep data, both the metadata and the raw data,from our side up to date with the resources. In addition, to comply with FAIR principles, each work isassigned a persistent identifier (PID) and indexed for searching purposes. In the last step, we perform somestandard analyses on the data to enhance our search engine and to generate a knowledge graph. End-userscan utilize our platform to search on our data or get access to the knowledge graph. Furthermore, they cansubmit their code for their analyses to the system. The code will be executed on a High-Performance Cluster(HPC) and users can receive the results later on. In this case, Flowable can take advantage of PIDs for digitalobjects identification and management to facilitate the communication with the HPC system. As one mayalready notice, the whole process can be expressed as a workflow. A workflow, including error handling andnotification, has been created and deployed. Workflow execution can be triggered manually or afterpredefined time intervals. According to our evaluation, the Flowable platform proves to be powerful andflexible. Further usage of the platform is already planned or implemented for many of our projects.

This paper introduces the MINE platform, which aims to help scientists overcome the difficulties in data acquisition and text analysis in a large scale. Foremost, MINE provides a search portal, which facilitates the data acquisition process by allowing users to search and download data across multiple repositories. After investigating other state-of-the-art systems on the market at the moment, we realize that they cannot satisfy the complexity of a text analysis workflow. Therefore, a text analysis workspace was created in MINE. This workspace gives users not only a chance to build their own analysis workflows, but also to execute them on a powerful and reliable infrastructure. Although this workspace is a promising feature, there are still some works to be done. However, we strongly believe that it will be released for public use in this year.

The Pencil Code is a highly modular physics-oriented simulation code that can be adapted to a wide range of applications. It is primarily designed to solve partial differential equations (PDEs) of compressible hydrodynamics and has lots of add-ons ranging from astrophysical magnetohydrodynamics (MHD) to meteorological cloud microphysics and engineering applications in combustion. Nevertheless, the framework is general and can also be applied to situations not related to hydrodynamics or even PDEs, for example when just the message passing interface or input/output strategies of the code are to be used. The code can also evolve Lagrangian (inertial and noninertial) particles, their coagulation and condensation, as well as their interaction with the fluid.

COST (European Cooperation in Science and Technology) is a funding organisation for research and innovation networks. One of the objectives of the COSTAction called “Mobilising Data, Policies and Experts in Scientific Collections“ (MOBILISE) is to work on documents for expert training with broad involvement of professionals from the participating European countries. The guideline presented here in its general concept will address principles, strategies and standards for long term preservation and archiving of data constructs (data packages, data products) as addressed by and under control of the scientific collections community. The document is being developed as part of the MOBILISE Action targeted towards primarily scientific staff at natural scientific collection facilities, as well as management bodies of collections like museums, herbaria and information technology personnel less familiar with data archiving principles and routines. The challenges of big data storage and (distributed, cloud-based) storage solutions as well as that of data mirroring, backing up, synchronisation and publication in productive data environments are well addressed by documents, guidelines and online platforms, e.g., in the DISSCo knowledge base (see Hardisty et al. (2020)) and as part of concepts of the European Open Science Cloud (EOSC). Archival processes and the resulting data constructs, however, are often left outside of the considerations. This is a large gap because archival issues are not only simple technical ones as addressed by the term “bit preservation” but also envisage a number of logical, functional, normative, administrative and semantic issues as addressed by the term “functional long-term archiving”. The main target digital object types addressed by this COST MOBILISE Guideline are data constructs called Digital or Digital Extended Specimens and data products with the persistent identifier assignment lying under the authority of scientific collections facilities. Such digital objects are specified according to the Digital Object Architecture (DOA , see Wittenburg et al. 2018) and similar abstract models introduced by Harjes et al. (2020) and Lannom et al. (2020). The scientific collection-specific types are defined following evolving concepts in the context of the Consortium of European Taxonomic Facilities (CETAF), the research infrastructure DiSSCo (Distributed System of Scientific Collections), and the Biodiversity Information Standards (TDWG). Archival processes are described following the OAIS (Open Archival Information System) reference model. The archived objects should be reusable in the sense of the FAIR (Findable, Accessible, Interoperable, and Reusable) guiding principles. Organisations like national (digital) archives, computing or professional (domain-specific) data centers as well as libraries might offer specific archiving services and act as partner organisations of scientific collections facilities. The guideline consists of key messages that have been defined. They address the collection community, especially the staff and leadership of taxonomic facilities. Aspects of several groups of stakeholders are discussed as well as cost models. The guideline does not recommend specific solutions for archiving software and workflows. Supplementary information is delivered via a wiki-based platform for the COST MOBILISE Archiving Working Group WG4.

The hot loop structures in the solar corona can be well modelled by three-dimensional magnetohydrodynamic simulations, where the corona is heated by field line braiding driven at the photosphere. To be able to reproduce the emission comparable to observations, one has to use realistic values for the Spitzer heat conductivity, which puts a large constraint on the time step of these simulations and make them therefore computationally expensive. Here, we present a non-Fourier description of the heat flux evolution, which allows us to speed up the simulations significantly. Together with the semi-relativistic Boris correction, we are able to limit the time step constraint of the Alfv?n speed and speed up the simulations even further. We discuss the implementation of these two methods to the Pencil Code? and present their implications on the time step, and the temperature structures, the ohmic heating rate and the emission in simulations of the solar corona. Using a non-Fourier description of the heat flux evolution together with the Boris correction, we can increase the time step of the simulation significantly without moving far away from the reference solution. However, for values of the Alfv?n speed limit of 3000 and below, the simulation moves away from the reference solution and produces much higher temperatures and much structures with stronger emission.

The Handle Software manages references to resources of information. However, it does not support a search functionality. A prior implementation with Elasticsearch could not efficiently capture the complex structure of our dataset, especially the relationships between handles. In this paper, we apply a graph database together with Elasticsearch to provide more search capabilities to users. In addition, the graph can efficiently store meta-data provided during handle creation. Further use cases for this graph include redundancy detection (two or more handles pointing to the same URL), or bibliographic network analysis.

The hot loop structures in the solar corona can be well modeled by three dimensional magnetohydrodynamic simulations, where the corona is heated by field line braiding driven at the photosphere. To be able to reproduced the emission comparable to observations, one has to use realistic values for the Spitzer heat conductivity, which puts a large constrain on the time step of these simulations and therefore make them computationally expensive. Here, we present a non-Fourier description of the heat flux evolution, which allow us to speed up the simulations significantly. Together with the semi-relativistic Boris correction, we are able to limit the time step constrain of the Alfvén speed and speed up the simulations even further. We discuss the implementation of these two methods to the Pencil Code and present their implications on the time step, and the temperature structures, the ohmic heating rate and the emission in simulations of the solar corona. We find that with the use of the non-Fourier description of the heat flux evolution and the Boris correction, we can increase the time step of the simulation significantly without moving far away from the reference solution. However, for too low values of the Alfvén speed limit, the simulation moves away from the reference solution und produces much higher temperatures and stronger emission structures.

ZusammenfassungDurch die Zunahme an digitalen Forschungsmethoden in den Geisteswissenschaften nimmt auch die Nachfrage nach Diensten zum Forschungsdatenmanagement rasant zu. Wir beschreiben die sich daraus ergebenden Herausforderungen und Perspektiven eines geisteswissenschaftlichen Datenzentrums zur nachhaltigen Sicherung und Bereitstellung digitaler Forschung am Beispiel des Humanities Data Centres.

Aims. We study the magnetic field and current structure associated with a coronal loop. Through this we investigate to what extent the assumptions of a force-free magnetic field break down and where they might be justified. Methods. We analyze a three-dimensional (3D) magnetohydrodynamic (MHD) model of the solar corona in an emerging active region with the focus on the structure of the forming coronal loops. The lower boundary of this simulation is taken from a model of an emerging active region. As a consequence of the emerging magnetic flux and the horizontal motions at the surface a coronal loop forms self-consistently. We investigate the current density along magnetic field lines inside (and outside) this loop and study the magnetic and plasma properties in and around this loop. The loop is defined as the bundle of field lines that coincides with enhanced emission in extreme UV. Results. We find that the total current along the emerging loop changes its sign from being antiparallel to parallel to the magnetic field. This is caused by the inclination of the loop together with the footpoint motion. Around the loop, the currents form a complex non-force-free helical structure. This is directly related to a bipolar current structure at the loop footpoints at the base of the corona and a local reduction of the background magnetic field (i.e., outside the loop) caused by the plasma flow into and along the loop. Furthermore, the locally reduced magnetic pressure in the loop allows the loop to sustain a higher density, which is crucial for the emission in extreme UV. The action of the flow on the magnetic field hosting the loop turns out to also be responsible for the observed squashing of the loop. Conclusions. The complex magnetic field and current system surrounding it can only be modeled in 3D MHD models where the magnetic field has to balance the plasma pressure. A one-dimensional coronal loop model or a force-free extrapolation cannot capture the current system and the complex interaction of the plasma and the magnetic field in the coronal loop, despite the fact that the loop is under low-beta conditions.

Research data is – regardless its disciplinary provenance – very heterogeneous in terms of data formats, applied research methods and content. In contrast to publications, a much broader spectrum of data representations has to be considered by research data infrastructures. Within the Humanities Data Centre project (HDC) an initial service portfolio for research data from the humanities has been developed in its design phase (2014–2016). Not only does this service portfolio has to facilitate the re-use of research data by third parties, a service anybody would expect as conventional for a research data centre, but it also has to provide novel benefits for the providers of research data to promote their contribution of data, documentation and support. As an example for these intended benefits for research data providers we will introduce two service components: the application preservation and the referencing of complex software environments. Jointly applied they enable researchers to archive and reference to complex representations of research data such as digital editions, virtual research environments, or data visualisations.

Complex software environments, like virtual research environments or visualisation frameworks, are increasingly used to conduct research and present its results. While there is a growing amount for solutions facilitating the (granular) citation of publications and research data, the citation of complex software environments remains a challenge. This abstract outlines the challenges and introduces an approach for referencing software environments developed in the Humanities Data Centre project: the application preservation.

Context. The structure and heating of coronal loops are investigated since decades. Established scaling laws relate fundamental quantities like the loop apex temperature, pressure, length, and the coronal heating. Aims. We test such scaling laws against a large-scale 3D MHD model of the Solar corona, which became feasible with nowadays high-performance computing. Methods. We drive an active region simulation a with photospheric observations and found strong similarities to the observed coronal loops in X-rays and EUV wavelength. A 3D reconstruction of stereoscopic observations showed that our model loops have a realistic spatial structure. We compare scaling laws to our model data extracted along an ensemble of field lines. Finally, we fit a new scaling law that represents well hot loops and also cooler structures, which was not possible before only based on observations. Results. Our model data gives some support for scaling laws that were established for hot and EUV-emissive coronal loops. For the RTV scaling law we find an offset to our model data, which can be explained by 1D considerations of a static loop with a constant heat input and conduction. With a fit to our model data we set up a new scaling law for the coronal heat input along magnetic field lines. Conclusions. RTV-like scaling laws were fitted to hot loops and therefore do not predict well the coronal heat input for cooler structures that are hardly observable. The basic differences between 1D and self-consistent 3D modeling account for deviations between our and earlier scaling laws. We also conclude that a heating mechanism by MHD-turbulent dissipation within a braided flux tube would heat the corona stronger than consistent with our model corona.

The outer solar atmosphere, the corona, contains plasma at temperatures of more than a million K, more than 100 times hotter that solar surface. How this gas is heated is a fundamental question tightly interwoven with the structure of the magnetic field in the upper atmosphere. Conducting numerical experiments based on magnetohydrodynamics we account for both the evolving three-dimensional structure of the atmosphere and the complex interaction of magnetic field and plasma. Together this defines the formation and evolution of coronal loops, the basic building block prominently seen in X-rays and extreme ultraviolet (EUV) images. The structures seen as coronal loops in the EUV can evolve quite differently from the magnetic field. While the magnetic field continuously expands as new magnetic flux emerges through the solar surface, the plasma gets heated on successively emerging fieldlines creating an EUV loop that remains roughly at the same place. For each snapshot the EUV images outline the magnetic field, but in contrast to the traditional view, the temporal evolution of the magnetic field and the EUV loops can be different. Through this we show that the thermal and the magnetic evolution in the outer atmosphere of a cool star has to be treated together, and cannot be simply separated as done mostly so far.

Context. We have conducted a 3D MHD simulation of the solar corona above an active region (AR) in full scale and high resolution, which shows coronal loops, and plasma flows within them, similar to observations.Aims. We want to find the connection between the photospheric energy input by field-line braiding with the coronal energy conversion by Ohmic dissipation of induced currents.Methods. To this end we compare the coronal energy input and dissipation within our simulation domain above different fields of view, e.g. for a small loops system in the AR core. We also choose an ensemble of field lines to compare, e.g., the magnetic energy input to the heating per particle along these field lines.Results. We find an enhanced Ohmic dissipation of currents in the corona above areas that also have enhanced upwards-directed Poynting flux. These regions coincide with the regions where hot coronal loops within the AR core are observed. The coronal density plays a role in estimating the coronal temperature due to the generated heat input. A minimum flux density of about 200 Gauss is needed in the photosphere to heat a field line to coronal temperatures of about 1 MK.Conclusions. This suggests that the field-line braiding mechanism provides the coronal energy input and that the Ohmic dissipation of induced currents dominates the coronal heating mechanism.