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The FinBIF (Schulman et al. 2021) Research Infrastructure is a national service with a broad coverage of the components of biodiversity informatics. Data flows are managed under a single information technology architecture, services are delivered through an on-line portal representing an umbrella concept and one brand. Data is collated from all available sources (e.g., research institute's data management systems, national monitoring schemes, natural history collection management systems and citizen science projects). Where does it stand between the local and international data infrastructures? The discussion among national stakeholders in Finland has been active under the themes of whether aggregating biodiversity data services would actually replace the local and organisation-level data services. The same discussion dwells on whether we need national level data aggregating services since we have the international infrastructures that provide, seemingly, the same services: data queries and data downloads. Through the years of agile development of FinBIF, since 2015, we have learned that all levels— local, national, and international data services—are very much needed since they all serve, in most cases, different purposes. At the local or institutional level, the biodiversity data managing and providing services are very much tailored to serve the tasks set to meet the responsibilities of the individual organisations. They are often not planned even to be interoperable with other data infrastructures that may be using or providing similar data. They rarely have a masterplan or a strategy that would have taken the big picture into account. However, they are often user-friendly, simple, and satisfying the basic needs. National level services, like FinBIF, on the other hand, have often a strategic approach to ensure data compilation and sharing with wide array of relevant users. Their challenge is the big number of potential users and their diverse needs and thus how to make a service so flexible that it would become useful for most. International data repositories may be similar to national level data services but are often lacking some crucial information like restricted-use or sensitive data. They are good for big data; they improve data findability and also with most developed data managing systems, they serve as a source of inspiration for smaller scale services. Finally, it became clear that the most important task, when serving all biodiversity data user groups, is to ensure the interoperability among the local, national, and international data infrastructures. Allowing uncomplicated data flows between different level data providers is a crucial step for the successful data FAIRification process.

This paper focuses on development of an existing 1 MV lightning impulse (LI) measuring system as part of European project for i.a. LI calibration capabilities development. After carefully characterization of the original LI divider a new low voltage arm was designed and built with e.g. improved shielding and also RC circuits for compensating the detected drift in the step response. With the compensation step response was successfully corrected resulting in clear improvements in LI time parameter measurements. However, persistent high frequency noise was present in the step response complicating further fine-tuning of the response. The noise could not much be improved at least partly due to non-optimal damping resistor structure, which is difficult to improve afterwards. After the improvements an extensive uncertainty evaluation was carried out for the original system as well as for two versions of the improved system.

Surface modification of nanoparticles is often utilized to tailor the interfacial properties in dielectric nanocomposites. Introducing different functional groups to the nanoparticles’ surface may induce localized states (traps) that can enhance the dielectric performance of the material depending on their density and energy levels. Furthermore, surface modification of the filler can affect the dispersion quality and crystallization of the nanocomposites which can ultimately alter the dielectric response of the material. In this study, functionalization of silica nanoparticles is demonstrated using 3-(trimethoxysilyl)propyl methacrylate (TMPM) and 1-[3-(trimethoxysilyl)propyl]urea (TMPU) as modifying agents. The effect of such modifications on the crystallization behavior, dispersion quality of the nanoparticles, as well as charge trapping and transport under a medium DC field is studied in nanocomposites based on polypropylene (PP)/ethylene-octene-copolymer (EOC) blends at 1% and 5% of filler concentrations. The results show that both ureido and methacrylate functional groups introduce localized states, but with different energy levels. Nitrogen containing ureido groups in TMPU tend to introduce deeper traps to the filler-polymer interfaces, compared to the methacrylate silane modification. Comparing the two types of surface functionalization, the ureido-functionalized silica resulted in a suppression of space charge formation at the interfaces under a medium DC electric field, despite the relatively larger mean cluster size of nanoparticles. publishedVersion

Dielectric polymer nanocomposites are considered as one of the most promising insulation material candidates for future capacitive energy storage applications, providing tailorability of charge trapping and transport properties at the nanometric level which is a key for increased dielectric performance of biaxially oriented polypropylene (BOPP) for metallized film capacitors in high-voltage direct current (HVDC) applications. In this study, a comprehensive investigation of morphology and dielectric performance of pilot-scale BOPP nanocomposites with hexamethyldisilazane (HMDS)-treated hydrophobic fumed silica nanoparticles was carried out, providing critical perspectives on the performance and challenges of PNCs for thin film capacitors also in a broader context. In non-oriented cast films, incorporation of nanosilica modified the crystallization kinetics and α/β-crystalline spherulitic morphology of polypropylene and reduced the accumulation of space charge under a DC electric field. The nanocomposites exhibited promising dispersion characteristics in the nano-scale, however, the low amount of micron-sized agglomerates inherently present in commercial fumed silica persisted in the compounds which can become critical for thin film applications. Subsequently, biaxial-stretching-induced morphology development and dielectric properties of silica-BOPP nanocomposites were evaluated, highlighting the role of precursor morphology and film processing in the silica-BOPP film morphology, defects and dielectric performance. Charge trapping and transport properties of silica-BOPP films were investigated by isothermal and thermally stimulated techniques under high DC electro-thermal stresses, indicating profound modification of the trap density of states brought about by nanosilica. This resulted in more homogeneous space charge distribution and reduced temperature- and field dependent DC conductivity at 100 °C in comparison to neat BOPP under moderate field stresses (

The effect of filler surface functionalization with 3-aminopropyltriethoxysilane (APTES) on the charge trapping and transport was studied in polypropylene (PP)/(ethylene-octene) copolymer (EOC)/silica nanodielectrics. Different reaction conditions were utilized for silica functionalization to alter the deposited layer morphology. This approach made it possible to engineer the filler–polymer interface to achieve optimized dielectric properties for the nanocomposites. The successful chemical modification of the silica surface was confirmed via thermogravimetric analysis (TGA), Fourier-transform infrared spectroscopy (FTIR), and X-ray photoelectron spectroscopy (XPS). Subsequently, the effect of the engineered filler–polymer interface on the nanocomposites’ crystallinity was analyzed with differential scanning calorimetry (DSC). Scanning electron microscopy (SEM) was utilized to observe the morphology of the nanocomposite as well as the silica dispersion. Finally, the effect of the silica functionalization on the dielectric properties of PP/EOC/silica nanocomposites was tested via thermally stimulated depolarization current (TSDC) and broadband dielectric spectroscopy (BDS). The results suggested that the presence of the amine functionality on the silica reduces interfacial losses in nanocomposites, and hinders further injection of space charge by introducing deep trap states at the filler–polymer interface. Under certain conditions, APTES can form an “island-like” morphology on the silica surface. These islands can facilitate nucleation, inducing transcrystallization at the filler–polymer interface. The island-like structures present on the silica would further contribute to the induction of deep traps at the filler–polymer interface resulting in the reduction of space charge injection. publishedVersion

This article presents a finite element (FE) method (FEM) based approach for identifying the dimension-independent magnetic and dielectric properties of Mn-Zn toroidal ferrite cores. Two 1-D axisymmetric FE models are utilized for solving the full-wave electromagnetic field equations in a toroidal ferrite core using either the electric field strength (E) or the magnetic field strength (H) as the variable. Impedance measurements are performed for the toroidal cores over a frequency range of 10 kHz - 10 MHz. The FE models and the impedance measurements are combined with a non-linear least squares algorithm for solving the inverse problem for extracting the dimension-independent values of the complex permeability and complex permittivity. The extracted permeability is validated against the datasheet of the measured samples. publishedVersion

New potential High Voltage Direct Current (HVDC) cable insulation materials based on nanocomposites are developed in this study. The nanocomposites are produced by blending of polypropylene (PP), propylene-ethylene copolymer (PP–HI) and a modified fumed silica (A-silica) in a concentration of 1 and 2 wt %. The A-silica is successfully modified with (3-aminopropyl)triethoxysilane (APTES) via a solvent-free method, as proven by infrared spectroscopy, thermogravimetry and transmission electron microscope mapping. A-silica in the polymer matrix acts as a nucleating agent resulting in an increase of the crystallization temperature of the polymers and a smaller crystal size. Moreover, the silica addition modified the crystals morphology of the unfilled PP/PP-HI blend. The composite containing A-silica with 2 wt% contains bigger-size silica clusters than the composite filled with 1 wt%. The composite with the higher A-silica concentration shows lower space charge accumulation and a lower charge current value. Besides, much deeper traps and lower trap density are observed in the composite with 2 wt% A-silica addition compared to the one with a lower concentration. Surprisingly, the presence of silica clusters with dimensions of more than 200 nm exhibit a positive effect on reducing the space charge accumulation. However, the real cause of this improvement might be due to change of the electron distribution stemming from the amine-amine hydrogen bond formation, or the change of the chain mobility due to the presence of occluded polymer macromolecules constrained inside the high structure silica clusters. Both phenomena may lead to a higher energetic barrier of charge de-trapping, thus increasing the depth of the charge traps. publishedVersion

Biodiversity informatics has advanced rapidly with the maturation of major biodiversity data infrastructures (BDDIs), such as the Global Biodiversity Information Facility sharing unprecedented data volumes. Nevertheless, taxonomic, temporal and spatial data coverage remains unsatisfactory. With an increasing data need, the global BDDIs require continuous inflow from local data mobilisation, and national BDDIs are being developed around the world. The global BDDIs are specialised in certain data types or data life cycle stages which, despite possible merits, renders the BDDI landscape fragmented and complex. That this often is repeated at the national level creates counterproductive redundancy, complicates user services, and frustrates funders. Here, we present the Finnish Biodiversity Information Facility (FinBIF) as a model of an all-inclusive BDDI. It integrates relevant data types and phases of the data life cycle, manages them under one IT architecture, and distributes the data through one service portal under one brand. FinBIF has experienced diverse funder engagement and rapid user uptake. Therefore, we suggest the integrated and inclusive approach be adopted in national BDDI development.

This study focuses on the influence of polar and unpolar surface functionalization of silica on the dielectric performance of PP/POE (polypropylene/poly(ethylene-co-octene)) nanocomposites. The silica fillers were surface-modified with unpoalr trimethylethoxysilane (TMES) or polar 3-aminopropyl triethoxysilane (APTES). Fourier-Transform Infrared Spectroscopy and Thermogravimetric analysis were performed and confirmed qualitatively and quantitatively the successful silica-silane modification. Silica/PP/POE nanocomposite films were prepared using a mini-extruder. Scanning Electron Microscope images showed good dispersion of the modified silica in the PP/POE matrix. However, the polar silica cluster size (300 nm) is slightly larger than the one of the unpolar silica (100 nm). Thermally Stimulated Depolarization Current (TSDC) characterization data showed that the polar silica introduced deeper charge traps than the unpolar one, which also showed higher trap density. The apparent conductivity measured during the TSDC poling phase indicated that the polar silica filled nanocomposites featured very fast polarization to reach the saturation state, while the unpolar silica had a rather slow polarization rate. From Pulsed Electroacoustic Analysis it was obvious that the space charge is suppressed by addition of the polar silica, but increased by the presence of the unpolar silica. acceptedVersion

This study compares different polymer-nanofiller blends concerning their suitability for application as insulating thermoplastic composites for High Voltage Direct Current (HVDC) cable application. Two polymer blends, PP/EOC (polypropylene/ethylene-octene copolymer) and PP/PP-HI (polypropylene/ propylene - ethylene copolymer) and their nanocomposites filled with 2 wt.% of fumed silica modified with 3-aminopropyltriethoxysilane were studied. Morphology, thermal stability, crystallization behavior dynamic relaxation, conductivity, charge trap distribution and space charge behavior were studied respectively. The results showed that the comprehensive performance of the PP/PP-HI composite is better than the one of the PP/EOC composite due to better polymer miscibility and flexibility, as well as lower charging current density and space charge accumulation. Nanosilica addition improves the thermal stability and dielectric properties of both polymer blends. The filler acts as nucleating agent increasing the crystallization temperature, but decreasing the degree of crystallinity. Dynamic mechanical analysis results revealed three polymer relaxation transitions: PP glass transition ( $\beta$ ), weak crystal reorientation ( $\alpha 1$ ) and melting ( $\alpha 2$ ). The nanosilica introduced deep traps in the polymer blends and suppressed space charge accumulation, but slightly increased the conductivity. A hypothesis for the correlation of charge trap distribution and polymer chain transition peaks is developed: In unfilled PP/EOC and PP/PP-HI matrices, charges are mostly located at the crystalline-amorphous interface, whereas in the filled PP/EOC/silica and PP/PP-HI /silica composites, charges are mostly located at the nanosilica-polymer interface. Overall, the PP/PP-HI (55/45) nanocomposite with 2 wt.% modified silica and 0.3 wt.% of antioxidants making it $a$ promising material for PP based HVDC cable insulation application with $a$ reduced space charge accumulation and good mechanical properties.

The Finnish Biodiversity Information Facility (FinBIF) Research Infrastructure (Schulman et al. 2021) is a national service with a broad coverage of the components of biodiversity informatics (Bingham et al. 2017). Data flows are managed under a single information technology (IT) architecture. Services are available in a single, branded on-line portal. Data are collated from all relevant sources e.g., research institutes, scientific collections, public authorities and citizen science projects, whose data represent a major contribution. The challenge is to analyse, classify and share good quality data in a way that the user understands its utility. Need for quality data The philosophy of FinBIF is that all observation records are important, and that all data are assessed for quality and able to be annotated. The challenge is that, in practice, many users desire data with 100% reliability. In our experience, most user concerns about data quality are related to citizen science data. Researchers are usually able to manage raw data to serve their purposes. However, decision-making authorities often have less capacity to analyse the data and thus require data that can be used instantly. Therefore, we need tools to provide users the data that are the most relevant and reliable for their specific use. For all users, standardized metadata (information about datasets) are key, when the user has doubts about the fitness-for-use of a particular dataset. There is also a need to provide data in different formats to serve various users. Finally, the service has to be machine-actionable (using an application programming interface (API) and R-package) as well as human-accessible for viewing and downloading data. Quality assignment FinBIF data accuracy varies significantly within and between datasets, and observers. Two quality-based classifications suitable for filtering are therefore applied. The dataset origin filter is based on the quality of a whole dataset (e.g. citizen science project) and includes three broad classes assigned with an appropriate quality label: Datasets by Professionals, by Specialists and by Citizen Scientists. The observation reliability filter is based on a single observation and on annotations by FinBIF users. This classification includes Expert verified, Community verified, Unassessed (default for all records), Uncertain, and Erroneous. The dataset origin does not necessarily determine the quality of the individual records in it. Observations made by citizen scientists are often accurate, while there may be errors in the professionally collected data. Records are frequently subject to annotation, which raises their quality over time (e.g., iNaturalist). Naturally, evidence (e.g., media, detailed descriptions, specimens) is needed for reliable identification. Annotating data When observations are compiled at FinBIF’s portal (Laji.fi), they are initially “Unassessed” (unless they have otherwise been assessed at the original source). When annotating occurrences, volunteers can make various entries using the tools provided. The aim of the commentary is to improve the quality of the observation data. Annotators are divided into two categories with two different roles: As a basic user, anyone who has logged in at Laji.fi can make comments or tag observations for review by experts. Users defined as experts have wider rights than basic users and their comments carry more weight. The most desired actions of expert users are to classify observations into confidence levels or to give them new or refined identifications. As a basic user, anyone who has logged in at Laji.fi can make comments or tag observations for review by experts. Users defined as experts have wider rights than basic users and their comments carry more weight. The most desired actions of expert users are to classify observations into confidence levels or to give them new or refined identifications. Information about new comments passes to the observer if the observation is recorded by using the FinBIF Observation Management System “Notebook”. However, comments cannot yet be automatically forwarded e.g., to the primary data management systems at the original source. Annotations add extra indications of quality. They do not replace or delete the original information. Nevertheless, annotations can change a record’s taxonomic identification, and by default, a record will be handled based on its latest identification. R-package for researchers and Public Authority Portal (PAP) for decision makers FinBIF has produced an R programming language interface to its API, which makes the publicly available data in FinBIF accessible from within R. For authorities, the PAP offers direct access to all available species information to authorised users, including sensitive and restricted-use data.

A novel hybrid approach for surface modification of nano-silica for polyolefin-based dielectric composites is presented. A fumed nano-silica was modified with long oligomeric chains of a liquid rubber, connected via urethane bonds to the silica surface increasing the compatibility with the matrix. Additionally, a secondary amino-silane was grafted in order to alter the charge trapping properties of the silica. The long oligomeric chains provide good dispersibility of the nanosilica in polypropylene/poly(ethylene-co-octene) (PP/POE) blends, while the functional urethane group along with a secondary amino-silane affected the charge trapping properties of the nano-composites by reducing the charge traps density and simultaneously increasing their depth. Scanning Electron Microscopy along with Differential Scanning Calorimetry revealed that the silica is preferably located in the PP phase, most likely due to its lower viscosity in comparison to POE. The silica particles exhibit a nucleating effect visible in a noticeable increase of the crystallization temperature of the PP phase, especially when the silica surface treatment is performed. acceptedVersion

This paper focuses on novel insulation polypropylene/poly(ethylene-co-octene) (PP/POE) nanocomposites for High Voltage Direct Current (HVDC) cable application. The composites contain silica modified by a solvent-free method using silanes differing in polarity and functional moieties. Thermogravimetric Analysis and Fourier Transform Infrared Spectroscopy showed that the solvent-free method is an effective way to modify silica by silanes. Silica/PP/POE nanocomposites were prepared in a mini twin-screw compounder, and the effect of silica on crystallization, dispersibility and dielectric properties of the samples was investigated. Differential Scanning Calorimetry results showed that the unmodified and modified silicas acted as nucleation agents and increased the onset of the crystallization temperature of the polymeric matrix. Scanning Electron Microscopy images showed that the silica is mostly located in the PP phase matrix. For the PP/POE nanocomposites filled with unpolar silica, a higher trap density (measured by Thermally Stimulated Depolarization Current, TSDC) was found; this might be caused by the larger interfacial area due to a better dispersion of the unpolar silica in the polymeric matrix. Polar silicas introduce deeper traps than the unpolar ones, which is most likely due to the hetero-atom introduction. Nitrogen atoms were found to have the strongest effect on the charge trapping properties. According to these results, amine-modified silica is a promising candidate for PP/POE nanocomposites for HVDC cable applications. publishedVersion

In this paper a route from laboratory scale samples to full industrial scale production of biaxially oriented silica-PP nanocomposite capacitor films is for the first time shown and verified. Morphological and dielectric characteristics of laboratory scale produced and by full industrial tenter -process produced nanocomposite and neat-PP reference films are presented and compared. In addition to the short-term characteristics also ageing performance of the industrial films are studied. The results show closely comparative dielectric behavior of the films and thus verifies the successful up-scaling of the used nanocomposite recipe. Although certain amount of impurities and voids were observed in both nanocomposite films the low probability dielectric breakdown strength characteristics were considered promising. Modified trap distribution, decreased conductivity and improved dielectric loss behavior has been verified for the nanocomposite film while areas of further development are also recognized. acceptedVersion

This study presents a critical evaluation of the effect of two different sample manufacturing techniques on the morphological and dielectric properties of polypropylene (PP)-based nanocomposites, namely mini-scale injection molding (IM) vs. pilot-scale cast film extrusion. Polarized light microscopy revealed that the IM specimen morphology exhibited a layered "skin-core" type morphology, largely differing from the spherulitic morphology of the corresponding extruded cast films. Higher degree of crystallinity in the IM specimens was evidenced by calorimetric and X-ray diffraction methods. The processing-dependent morphological differences were found to affect the isothermal charging current (ICC) and thermally stimulated depolarization current (TSDC) characteristics due to differences in charge mobility and trapping, thus making direct comparison of IM and cast film specimens non-straightforward. Nevertheless, mini-scale injection molding can be seen as a resource-efficient sample manufacturing method for facilitating early-stage screening of the best-performing material candidates, given that the morphological features are carefully taken into account. I. INTRODUCTION The engineering dielectric properties of semi-crystalline polymers are known to be closely related with their crystalline structure and bulk morphological features. For instance, the processing-dependent morphology evolution at different scales of structures ranging from small (lamellar) to large (e.g. spherulitic) scale dictates the formation and dielectric properties of the crystalline-amorphous interface [1], thus making processing and specimen preparation non-trivial factors when evaluating and comparing dielectric performance of new materials [2]-[4]. PP based nanocomposite materials are currently being developed for high voltage direct current (HVDC) cable insulation applications in the EU project GRIDABLE, involving material optimization, compounding and sample manufacturing at several different batch sizes at VTT. Recently, mini-scale compounding and injection molding have been identified as a potential resource-efficient alternative for pilot-scale compounding and cast film extrusion to facilitate early-stage screening of the best-performing material candidates. This paper presents a critical comparison of the morphological and dielectric features of PP-based mini-injection molded and extruded cast film specimens, and evaluates the feasibility of the mini-injection molding technique for assessing the effect of nanosilica on the charge trapping and transport properties of PP based nanocomposites. acceptedVersion

Novel nanocomposites for dielectric applications-based polypropylene/poly(ethylene-co-octene) (PP/POE) blends filled with nano silica are developed in the framework of the European &lsquo, GRIDABLE&rsquo, project. A tailor-made low-pressure-plasma reactor was applied in this study for an organic surface modification of silica. Acetylene gas was used as the monomer for plasma polymerization in order to deposit a hydrocarbon layer onto the silica surface. The aim of this modification is to increase the compatibility between silica and the PP/POE blends matrix in order to improve the dispersion of the filler in the polymer matrix and to suppress the space charge accumulation by altering the charge trapping properties of these silica/PP/POE blends composites. The conditions for the deposition of the acetylene plasma-polymer onto the silica surface were optimized by analyzing the modification in terms of weight loss by thermogravimetry (TGA). X-ray photoelectron spectroscopy (XPS) and energy-dispersive X-ray fluorescence spectroscopy (EDX) measurements confirmed the presence of hydrocarbon compounds on the silica surface after plasma modification. The acetylene plasma modified silica with the highest deposition level was selected to be incorporated into the PP/POE blends matrix. X-ray diffraction (XRD) showed that there is no new crystal phase formation in the PP/POE blends nanocomposites after addition of the acetylene plasma modified silica. Differential scanning calorimetry results (DSC) show two melting peaks and two crystallization peaks of the PP/POE blends nanocomposites corresponding to the PP and POE domains. The improved dispersion of the silica after acetylene plasma modification in the PP/POE blends matrix was shown by means of SEM&ndash, EDX mapping. Thermally stimulated depolarization current (TSDC) measurements confirm that addition of the acetylene plasma modified silica affects the charge trapping density and decreases the amount of injected charges into PP/POE blends nanocomposites. This work shows that acetylene plasma modification of the silica surface is a promising route to tune charge trapping properties of PP/POE blend-based nanocomposites.

Breakdown strength, DC resistivity, permittivity and loss of thermally sprayed alumina coatings were studied at various temperatures and relative humidities. The studied coatings were sprayed by utilizing three different spray techniques: flame, high-velocity oxygen fuel (HVOF) and plasma spraying. Breakdown behavior of HVOF sprayed alumina were studied up to very high temperatures (800 °C). At 20-180°C, no significant trend could be seen in the breakdown strength of HVOF and plasma sprayed alumina coatings. The breakdown strength of alumina coatings decreased gradually from 300 to 800 °C reaching a value which was only 14% of the breakdown strength measured at 20 °C/RH 20%. Increasing humidity (from 20 to 90%) decreased the DC resistivity of the alumina coatings five orders of magnitude. Correspondingly, permittivity and losses increased with the humidity; in most cases with a notable contribution due to DC conduction. The material behavior may be linked to the microstructure of coatings consisting of amorphous and crystalline regions with interfaces in between. Moreover, the alumina coatings exhibited notable amount of highly hygroscopic γ-phase which also affected the moisture sensitivity of the coatings. acceptedVersion

Polymers have been extensively applied in the industry, especially in energy system e.g. due to their good processability and insulation properties. However, all polymers are permeable in different extent, which requires a good knowledge about the process of permeation through these materials. In this study the moisture dynamics of four different surge arresters were studied in several ways,—at first by analysing the moisture diffusion properties of the housing polymers and finally by testing the full arrester structures against moisture ingress. Housing polymer composites were evaluated using thermogravimetric analysis and differential scanning calorimetry while the polymers’ ability to withstand moisture diffusion was studied by water vapor transmission rate measurements. Moisture ingress behavior of the full surge arresters was examined by daily measurements of internal resistive leakage current along 30 days immersion test. Although correlations were found between the material composition and the diffusivity through the polymer, the moisture dynamic is deemed to be much more complex in the full surge arrester. Moisture permeation through separate housing material samples was typically high compared to internal leakage current formed in real arresters which highlights the main conclusion drawn,—internal structures and long term quality of interfaces are the key issues in preventing moisture induced degradation in metal oxide surge arresters.

Biaxial-stretching-induced morphology development and dielectric properties of hydrophobic fumed silica-BOPP nanocomposite films were investigated. The precursor (cast) film morphology, pre-heating as well as biaxial stretching temperature and stretch ratio were found to profoundly affect the silica-BOPP film bulk morphology, surface texture and the formation of particle/agglomerate-induced cavitation upon biaxial stretching. Isothermal high-field conductivity and thermally stimulated depolarization current measurements indicated decreasing high-field/high-temperature conductivity and modification of trap density of states upon incorporation of nanosilica in comparison to neat BOPP. Large-area DC dielectric strength is, however, sensitive to thermal/mechanical stresses upon biaxial stretching, hence necessitating careful optimization of the nanocomposite formulation and processing. publishedVersion

A systematic study of the influence of surface modification of nanosilica with coupling agents having different polarities on the dielectric properties of a PP/POE/silica blend was performed. The main goal of this investigation was to tailor the chemical composition of the silica surface, in order to modify the charge trapping properties of the nanocomposites. For the modification of the silica surface, a “green” approach was utilized: a dry silanization method, which is performed without the need of a solvent. The results of the thermogravimetric analysis (TGA) indicate that the dry process is an effective method to perform silica surface modification using alkoxysilanes. The charge trapping properties were studied by Thermally Stimulated Depolarization Current (TSDC) measurements. The obtained TSDC results show significant differences in charge trapping properties of PP/POE composites filled with differently modified silicas. Polar functional groups attached to the surface of the silica appear to have a strong effect on the charge trapping properties: The trap depth distribution becomes deeper and the trap density decreases to significantly lower levels. All results show that incorporation of surface modified nanosilica into a PP/POE matrix is a promising approach to tailor its dielectric properties. Further development of these composites may lead to benefits for application in high-voltage cable and capacitor applications. Keywords: silica surface modification, dry silanization, charge trapping, PP, POE, TSDC, high voltage cable. publishedVersion

The measurement and interpretation of high-field thermally stimulated depolarization current (TSDC) of capacitor-grade biaxially oriented polypropylene (BOPP) films are investigated in order to facilitate the derivation of trap parameters. Two main relaxations associable with the glass transition and detrapping of space charge from deep traps are observed, and their dependence on the polarization/depolarization conditions are studied. The complex bipolar nature of the space charge relaxation makes the derivation of trap parameters challenging. Lastly, a brief attempt is made to correlate the TSDC features with morphology and other short-term dielectric properties. publishedVersion

The Finnish Biodiversity Information Facility FinBIF (LINK: species.fi), operational since late 2016, is one of the more recent examples of comprehensive, all-inclusive national biodiversity research infrastructures. FinBIF integrates a wide array of biodiversity information approaches under the same umbrella. These include species information Fig. 1 (e.g. descriptions, photos and administrative attributes); citizen science platforms enabling recording, managing and sharing of observation data; an e-learning environment for species identification; management and sharing of restricted data among authorities; building a national DNA barcode reference library and linking it to species occurrence data; community-driven species identification support; large-scale and multi-technology digitisation of natural history collections; and IUCN Red Listing to conduct a periodic national assesment of the status of the threatened species. To improve the taxonomic coverage and the content of species information, FinBIF is starting a process to collaborate with the species information community at large, in order to collate already existing but not yet openly distributed information. This also means digitisation of information from analogue sources. In addition, the attempt is to join forces with Scandinavian counterparts, namely Artdatabanken (LINK: https://www.artdatabanken.se/) and Artsdatabanken (LINK: https://www.artsdatabanken.no/), for more efficient knowledge exchange within the countries sharing the same biogeographical region and thus similar species composition. The aim is also to reach politically high level agreement for deeper and wider commitment to collaborate in compiling, digitising and sharing relevant biodiversity information over the national borders.

The service model of the Global Biodiversity Information Facility (GBIF) is being implemented in an increasing number of national biodiversity (BD) data services. While GBIF already shares >109 data points, national initiatives are an essential component: increase in GBIF-mediated data relies on national data mobilisation and GBIF is not optimised to support local use. The Finnish Biodiversity Information Facility (FinBIF), initiated in 2012 and operational since late 2016, is one of the more recent examples of national BD research infrastructures (RIs) – and arguably among the most comprehensive. Here, we describe FinBIF’s development and service integration, and provide a model approach for the construction of all-inclusive national BD RIs. FinBIF integrates a wide array of BD RI approaches under the same umbrella. These include large-scale and multi-technology digitisation of natural history collections; building a national DNA barcode reference library and linking it to species occurrence data; citizen science platforms enabling recording, managing and sharing of observation data; management and sharing of restricted data among authorities; community-driven species identification support; an e-learning environment for species identification; and IUCN Red Listing (Fig. 1). FinBIF’s aims are to accelerate digitisation, mobilisation, and distribution of biodiversity data and to boost their use in research and education, environmental administration, and the private sector. The core functionalities of FinBIF were built in a 3.5-year project (01/2015–06/2018) by a consortium of four university-based natural history collection facilities led by the Finnish Museum of Natural History Luomus. Close to 30% of the total funding was granted through the Finnish Research Infrastructures programme (FIRI) governed by the national research council and based on scientific excellence. Government funds for productivity enhancement in state administration covered c.40 % of the development and the rest was self-financed by the implementing consortium of organisations that have both a research and an education mission. The cross-sectoral scope of FinBIF has led to rapid uptake and a broad user base of its functionalities and services. Not only researchers but also administrative authorities, various enterprises and a large number of private citizens show a significant interest in the RI (Table 1). FinBIF is now in its second construction cycle (2019–2022), funded through the FIRI programme and, thus, focused on researcher services. The work programme includes integration of tools for data management in ecological restoration and e-Lab tools for spatial analyses, morphometric analysis of 3D images, species identification from sound recordings, and metagenomics analyses.

Various dielectric nanocomposite materials are studied in the frame of the European Commission funded project GRIDABLE. This project has the aim to develop DC cable extruded insulation and medium and low voltage DC capacitor films exhibiting enhanced performance with respect to presently used materials. The nanocomposites intended for cable applications are based on polypropylene (PP) blends filled with surface modified nano-silica particles. The surface modification is carried out via the state-of-the-art solution method using a polar silane as the modifying agent. Thermally Stimulated Depolarization Current (TSDC) measurements were carried out in order to study the charge trapping behavior of the nanocomposite samples. TSDC results indicate that the addition of the treated nano-silica, for most cases, reduces the density of the deep traps significantly. While more detailed studies are necessary, these results imply that the depth and the density of the deep trap states is profoundly influenced by the level of the silica modification i.e. the amount of the grafted silane on the silica surface. acceptedVersion

Kotka is a collection management system (CMS) developed by the Finnish Museum of Natural History (Luomus) and used by all major institutes with natural history collections in Finland. It is one of the primary data sources of the Finnish Biodiversity Information Facility through which the data managed in Kotka is distributed (species.fi). Kotka is designed to allow flexible development of new tools to support collection management practices. This paper describes some of the tools included in Kotka. Label designer Printed labels have traditionally been used to store and display data about specimens. In modern collection informatics their role in connecting specimens to electronic data and in collection and data curation is emphasised. Requirements for the labels are changing rapidly and different types of specimens have completely different label designs. To give the collection managers an option to design suitable labels to meet their needs, we have created a WYSIWYG (What You See is What You Get) label designer (Fig. 1). It allows users to pick desired data fields and arrange them on the label, adjust styles and sizes, and generate HTTP-URI identifiers with QR Codes (Quick Response Codes). The label designer can be used with a modern web browser or as a standalone desktop application, on both Windows and Mac. It is open source and can be integrated with other applications by using it as an Angular module or as an custom element to any site. The label designer serves both scientific natural history collection managers and amateurs managing private collections. At Luomus the tool is used both in the Kotka CMS and in the Notebook system for species occurrence records. Annotations As collections are increasingly used and managed digitally, the traditional means of quality control and data improvement are no longer sufficient. We have developed tools which allow e.g. external researchers and citizen experts to review specimen data online at species.fi (species.fi), and annotate the data by evaluating its quality, propose and/or change species identifications and include comments. The annotations are delivered to collection managers who can then use them to update and improve the specimen data at the primary data source. QR Code reader Modern specimen labels often include specimen identifiers such as QR Codes or barcodes. To improve collection management efficiency, we have made a QR Code reader application, which allows collection managers to read these codes and display specimen data quickly on a handheld device (e.g. mobile phone) or a desktop computer with a web camera. The application is open source and can be configured to connect to any system utilizing HTTP-URI identifiers.

This paper presents a preliminary feasibility investigation, in the framework of a recent European project, GRIDABLE, aiming at the development of nanostructured Polypropylene, PP, materials as insulation for DC LV-MV capacitors and MV-HV cables. Results of electrical property characterization of various types of PP-SiO 2 materials for DC capacitors are presented in this paper, focusing on breakdown strength and space charge measurements. They indicate that the nanofiller may influence the degradation rate of materials, modifying the space charge accumulation dynamics and extent, as well as the threshold field value for space charge accumulation. Statistical analysis of breakdown voltage shows that the presence of nanoparticles may also improve noticeably the breakdown behavior.

Fumed silica-filled polypropylene (PP)-based nanodielectrics were studied in this work. To not only improve the dispersion of the silica but also introduce deep charge traps into the polymeric matrix, five types of modified silicas were manufactured with different surface modifications. The modified silica surfaces comprise an inner and a surface layer. The inner layer contains a polar urethane group for tailoring the charge trap properties of the PP/propylene–ethylene copolymer nanocomposites, whereas the surface layer consists of hydrocarbons (ethyl-, tert-butyl-, cyclopentyl-, phenyl-, or naphthalenyl moieties) in order to gain a good dispersion of the silica in the unpolar polymer blend. Scanning electron microscopic pictures proved that these tailored silicas show a much better dispersion than the unmodified one. Thermally stimulated depolarization current measurements revealed the ability of the silica to introduce deep charge traps with low trap density. The trap depth distribution depends on the type of the unpolar surface layer consisting of the different hydrocarbons. Among these five differently modified silicas, the introduction of the one with a surface layer consisting of tert-butyl moieties resulted in the lowest charge injection and the lowest charge current in the nanocomposite, proving good dielectric performance. Additionally, this silica exhibits good dispersion in the polymeric matrix, indicating a promising performance for nanodielectric application.

This study presents preliminary results on the morphology, structure and dielectric properties of laboratory scale cast and biaxially oriented silica-PP films, currently being developed in the European project GRIDABLE. Space charge measurements on the thick cast films indicated a reduction of positive space charge and faster depolarization characteristics upon inclusion of nano-silica, being indicative of reduction of trap depth and density distribution in comparison to neat PP. Likewise, for the biaxially oriented silica-PP thin films, increased amount of shallow traps and a reduction of concentration of traps in the deep trap range (∼ eV) were observed. Nano-silica was also found to reduce the dielectric loss at high temperatures in the frequency range appropriate to use. Such dielectric property modifications can potentially lead to benefits for insulation reliability and lifetime, especially at higher temperatures. A two-step compounding via a master batch approach was also found to be a viable option for the up-scaling of nanocomposite production.

This paper presents space charge accumulation characteristics of cable grade and capacitor grade nanostructured polypropylene (PP) materials, providing initial results regarding the electrical properties of nanofilled PP materials belonging to the European project GRIDABLE. This project has the aim to develop DC cable extruded insulation and MV and LV DC capacitor films having enhanced performance with respect to presently used materials. The paper shows that nanostructuration may be beneficial, especially at higher temperature, to improve the capacitor-grade material performance. On the other hand, this work validates the importance of surface functionalization of nanofillers, leading to lower space charge accumulation on DC cable-grade materials. acceptedVersion

This paper examines the morphology and short-term dielectric performance of commercial capacitor BOPP films, with the purpose of serving as an industrial reference in European project GRIDABLE in which next-generation PP-silica nanocomposite materials are developed for DC capacitor and cable applications. Results from dielectric spectroscopy, thermally stimulated depolarization current (TSDC) and DC conductivity measurements are reported, providing insight into the dielectric loss behavior and charge trapping/transport properties of the studied films. Comprehensive short-term dielectric breakdown strength analysis using small- and large-area approaches indicates high dielectric breakdown performance, even at an elevated temperature of 100 °C. acceptedVersion

In this work space charge accumulation characteristics of nanostructured polypropylene films are investigated, providing preliminary results for the basis of the new materials formulations to be developed in the European project GRIDABLE, where novel MV and LV DC capacitor films having enhanced performance with respect to present polypropylene films are being developed. This paper shows that nanostructuration may be beneficial, especially at higher temperature, to improve material performance. Better space charge performance will help in optimizing the dielectric strength, design field and reliability of the insulation system for DC use. acceptedVersion

Effects of cast film extrusion and biaxial orientation on morphological development and DC dielectric breakdown performance of non-oriented and biaxially oriented polypropylene (BOPP) films were studied. Cast films, based on two capacitor-grade isotactic polypropylene (iPP) homopolymers, were manufactured using three different extruders under different crystallization conditions and subsequently biaxially oriented using a laboratory stretching machine. Analysis of polymorphic composition and microstructural features was carried out in conjunction with large-area multi-breakdown performance assessment under progressive DC voltage ramp conditions. Polymorphic α/β-form crystalline composition and spherulitic/trans-crystalline morphology formed during cast film extrusion were found to directly affect the biaxially oriented film morphology and breakdown characteristics. For the BOPP films, decrease in dielectric strength was traced back to β→α crystal transformation and subsequent microvoid/porosity formation upon biaxial stretching. Topographical features and increasing surface roughness were also found to correlate with lower BOPP film dielectric strength. Dependence of breakdown strength on the biaxial stretch ratio was demonstrated, with higher biaxial stretch ratio resulting in improved BOPP film breakdown performance. As an extreme case, the biaxially oriented films were compared against non-oriented cast films in similar thickness range, highlighting the essential role of biaxial orientation in the high-dielectric-performance of thin films in capacitor applications. Control of polymer design as well as optimization of film processing and morphological development was found to be necessary to avoid formation of structural defects and loss of electrical insulation integrity. acceptedVersion

Previous studies of dielectric properties of thermally sprayed insulating ceramic coatings are focused on linearly ramped dielectric breakdown strength as well as DC resistivity, relative permittivity and dielectric loss characterizations. However, reports of the effects of ramp rate or of any kind of long term stressing on the breakdown strength cannot be found in literature. The aim of this paper was to study the DC breakdown behavior of one type of HVOF sprayed alumina coating under different stresses. It can be concluded that the ramp rate of DC breakdown measurement has no remarkably influence on the breakdown strength. The breakdown behavior was also studied using step-by-step tests with two constant step voltages and step durations. The DC resistivity of the alumina coating showed strong dependence on the applied electric field. The resistivity behaved ohmicly below the field strength of ~0.5 V/µm and above ~8…12 V/µm, however, the resistivity decreased approximately three decades in the nonohmic region (0.5 V/µm). At electric field strengths above ~25 V/µm, the degradation started in the material leading to breakdown. However, when the step duration was longer (60 min), the degradation process started already slightly below the applied field of 25 V/µm. acceptedVersion

The effect of temperature on the breakdown performance of metallized capacitor-grade BOPP film was characterized using a large-area multi-breakdown measurement method. The measurements conducted in the temperature range from room temperature to 100 °C revealed a linearly decreasing trend in the characteristic 63.2 % breakdown probability after 60 °C and the presence of a smaller weak spot subpopulation. The weak spots remained relatively unaffected by temperature, and first breakdowns occurred in a seemingly statistical manner. The brief exposure to elevated temperature was considered as one explanation behind the variations in the number of weak points, but fluctuations in film quality and Weibull dynamics were seen are more probable explanations. The results demonstrate the possibility of multiple breakdown mechanisms and their different temperature-dependency, and demonstrate the high short-term breakdown strength of BOPP film even at high temperatures.

This paper outlines our recent study on effects of cast film extrusion and biaxial orientation on the morphological development and dielectric performance of biaxially oriented polypropylene (PP) films based on two capacitor-grade isotactic PP (iPP) raw materials. Results on polymorphic composition, melting behavior, microstructure and dielectric properties are reported. Morphological development during film manufacturing is found to have a profound effect on film structure and dielectric characteristics. Formation of structural defects was traced back to β→α crystal transformation upon biaxial stretching. publishedVersion

In this study, the DC conductivity from low electric fields up to breakdown fields is studied for several different thermally sprayed ceramic coatings. Although the DC conductivity of bulk alumina ceramic has been observed to follow the space charge limited current conduction mechanism, the studied ceramic coatings do not follow or follow only partly this mechanism. Possible reason for this is their different microstructure since bulk alumina exhibits fully crystalline microstructure while the ceramic coating consists of crystalline and amorphous regions as well as voids, defects and numerous interfaces. A possible conduction mechanism of the ceramic coatings based on the different conductivities of the amorphous and crystalline regions of the coatings is proposed. The microstructural features (e.g. volumetric porosity) are found to affect the breakdown strength for some of the studied coatings. The step-test breakdown strengths of the coatings were lower than the ramp-test ones due to the longer stress durations in step tests giving an indication of effects of electrical stress duration and possible short-term degradation of the coatings. acceptedVersion

A large-area electro-thermal ageing test setup was developed and utilized to age several laboratory-scale biaxially oriented polypropylene (BOPP)–hydrophobic silica nanocomposite films. The films were aged in test capacitors with self-healing metallized film electrodes, which enabled the ageing test to continue beyond the first breakdowns. Eight different films were aged for 1000 hours under 100 V/µm DC stress at 75 °C, and large-area DC breakdown measurements, dielectric spectroscopy, gel permeation chromatography (GPC), differential scanning calorimetry (DSC) and dielectric spectroscopy were used to detect localized and bulk degradation after the ageing period. The effects of antioxidant contents, different PP grades and compounder screw speed were evaluated. Material characterization indicates no bulk degradation had occurred during ageing, which was associated with moderate temperature stress and inert nitrogen atmosphere. On the other hand, low-field breakdowns (weak points) were observed in all but two of the aged materials, indicating that ageing was dominated by localized degradation which may have introduced new breakdown mechanisms. Weak points were also measured in a similarly aged commercial capacitor-grade BOPP film aged at a lower field, supporting this conclusion. The importance of long-term characterization in material development is demonstrated, and it is shown that long-term properties of the evaluated nanocomposites were at least on the same level compared to neat BOPP films. acceptedVersion

A large-area high temperature breakdown measurement and an ageing test method are presented. These methods facilitate the development of reliable higher energy density film capacitors by exploiting large measurement areas to provide information on weak point formation and subtle changes in breakdown behavior after electro-thermal or thermal ageing. The test methods were used to characterize two types of highly isotactic biaxially oriented polypropylene capacitor films, which had similar breakdown behavior at room temperature, but different breakdown properties at high temperature and out of which one was more susceptible to electro-thermal DC ageing. acceptedVersion

This technical report describes an experimental analysis of metal–oxide surge arresters applied to power distribution network. This analysis is performed from periodical measurements of leakage current of the samples and hydrophobicity of the external polymeric housing correlated to the aging/degradation process by saline water immersion at 90 °C for 3 months, in order to simulate 20 years of field application. Based on this evaluation, the useful life and time degradation of polymer arresters are analyzed from the progressive variation of their electrical characteristics as a function of the immersion time.

A new dielectric breakdown measurement method for determining breakdown characteristics of polymer films has been developed and evaluated. The method is based on measurement of multiple breakdowns per sample area beyond the weakest point of the film by utilizing low-energy self-healing breakdown of metallized polymer film. A data selection process based on the discharge energy characteristics of each measured self-healing breakdown is utilized prior to the statistical analysis in order to validate the mutual independence of the results. Even with a relatively small sample area, the method yields a large amount of breakdown data from a wide voltage spectrum, thus enabling the formation of detailed material-specific breakdown fingerprints. The measurement system and the area dependence of the breakdown results have been evaluated with capacitor-grade metallized film. For the statistical analysis, additively mixed Weibull distributions are utilized as multiple breakdown mechanisms are found to be operative in the dielectric. Defects in the dielectric volume are found to have a profound effect on the structure of the mixed distribution with increasing area.

In order to improve the reliability of the energy system, a variety of techniques to access the condition monitoring of important equipment connected to the network have been developed in the past decades. However, it is important to choose the adequate method when evaluating the behavior of these devices. In this way, the current work aims to compare three techniques used to evaluate the condition of metal oxide surge arrester based on the decomposition of leakage current into its capacitive and resistive components. Each method was described in detail and their results compared.

Thermally sprayed insulating ceramic coatings can be utilized in conditions where polymers are inapplicable. The coatings exhibit a special lamellar microstructure with interfaces and some defects (e.g. voids, cracks) in between. The aim of this study was to analyze the relationship between the microstructural features and the dielectric properties of various thermally sprayed ceramics. The structural characterization of the ceramic coatings was made based on following properties: porosity, volumetric gas permeability and the characteristic size of crystalline lamella. High gas permeability of the coatings decreased the breakdown strength but similar effect cannot be seen in the DC resistivity and the permittivity results. Decrease of DC resistivity at high humidity did not correlate to microstructural properties; rather it is speculated to indicate the hydrophilic nature of the coatings. The characteristic crystalline domain sizes showed no clear correlation with the dielectric properties. acceptedVersion