Aqueous dispersions of single-walled carbon nanotubes (SWCNTs) with a surfactant were studied by using a combination of differential sedimentation and dynamic light scattering methods. When applied to elongated particles like SWCNTs, the differential sedimentation method makes it possible to measure their diameters in dispersions, while the dynamic light scattering method allows to measure their lengths. Both methods have logarithmic dependence on the ratio between the length and diameter of the particles, and their simultaneous use improves the accuracy of measuring particles' dimensions. It was shown that sonication of dispersions leads not only to unbundling of agglomerates into individual nanotubes but also to a decrease in their lengths and the appearance of new defects detectable in increasing the D/G ratio in the Raman spectra. Unbundling into individual nanotubes occurs after exposure to 1 kWh/L energy density, and the single nanotube diameter with SDBS is ca. 3.3 nm larger than that of the naked nanotubes. Conductivity of thin SWCNT films made out of individual nanotubes demonstrates a power law dependence with the exponent close to the theoretical one for rigid rods.

Recycled carbon fibers (rCF) represent an inexpensive alternative to virgin carbon fibers (CF) but the mechanical improvement brought by rCF to polymer composites is noticeably lower than that from CF. In this article we evaluate two methods of coating rCF by single walled carbon nanotubes (SWCNTs), wet and dry, and demonstrate that extremely low concentrations of SWCNTs, ∼0.03%, are sufficient to measurably improve the strength (by 16%), modulus (by 38%), and Izod impact strength (by 52%) of thermoplastic crystalline polyamide polyxylylene adipamide (MXD6) with 30% rCF. The dry method with grinding of rCF and SWCNTs works better than the wet (dip coating) method and the rCF with residual epoxy is better than purified by pyrolysis rCF. We link this improvement of the mechanical properties to the enhanced crystallization rate caused by SWCNTs, which is observed in differential scanning calorimetry (DSC).

Linear and symbol-level precoding in satellite communications have received increasing research attention thanks to their ability to tackle inter-beam interference, allowing the use of spectral resources more efficiently. However, there are still challenges and open questions regarding the implementation of practical precoding systems taking the phase uncertainties in estimating the channel state information into account. This work assesses the impact of phase variations and uncertainties inherent to the satellite communication system operating a precoded forward link. Specifically, we address the inability to measure at the user terminal, the absolute phase rotation introduced by the channel, and the transponder local oscillator phase noise effects on the precoding operations considering the use of frequency division multiplexing in the forward-uplink transmission. We formally demonstrate that the system performance for linear and non-linear precoding operations is not affected by the uncertainty in the phase measurements at the user terminal. Additionally, we show that using a single frequency reference for all the local oscillators at the transponder does not avoid the phase variations related to the frequency division multiplexing in the forward-uplink. This work demonstrates that these phase variations would not affect the system performance for an ideal zero-delay precoding loop. However, this is not feasible in practical scenarios, where the phase noise of the frequency reference at the transponder and the loop delay determine the impact on the system performance. We validate our results by simulations considering three frequency references with different stability levels in a typical geosynchronous orbit (GEO) satellite system. Our results suggest that practical implementations of multiuser-MISO precoding systems must include a differential phase synchronization loop to compensate for this performance degradation.

This is not a comprehensive review on the topic of single walled carbon nanotubes (SWCNTs). Because it is very broad - a simple search on ‘carbon nanotubes’ provides well over a million citations - we are focusing on a brand of SWCNTs produced by our company, OCSiAl, trademarked as TUBALL™ or just Tuball. It is a well-known product on the market and there is a good citation record on the applications of Tuball in industry and research labs, see Fig. 1. Despite this, there is no published data in the literature properly referencing its quality and the examples of its applications are often left without sufficient characterization. Because of that, we feel that it is well overdue to have a proper summary accessible to many researchers. Besides, the beneficial properties of SWCNT augments in many applications very strongly depend on the quality of SWCNTs and the methods of their introduction into materials. We have a few successful demonstrations here, some of which have not been published yet, and a plenty of additional published results with Tuball nanotubes are included as well.

In the first part [1] we discussed the structural and physicochemical properties of single walled carbon nanotubes (SWCNTs) with the emphasis on TUBALL™ produced by OCSiAl. This part focuses on the applications of Tuball capitalizing on its unique properties. We start with discussing the methods for dispersing SWCNTs in various media suitable for maximizing their positive effect on the mechanical, electrical, and other functional properties of the composites. It follows by the examples of applications of Tuball in materials for batteries, thermosets, thermoplastics, and elastomers, most of which employ commercially produced liquid and semisolid dispersions offered by OCSiAl. This demonstrates the real versatility of Tuball augmentation for improvement of electrical and mechanical properties of various materials and should stimulate its wide application.

Hawkes processes are temporal self-exciting point processes. They are well established in earthquake modelling or finance and their application is spreading to diverse areas. Most models from the literature have two major drawbacks regarding their potential application to insurance. First, they use an exponentially-decaying form of excitation, which does not allow a delay between the occurrence of an event and its excitation effect on the process and does not fit well on insurance data consequently. Second, theoretical results developed from these models are valid only when time of observation tends to infinity, whereas the time horizon for an insurance use case is of several months or years. In this paper, we define a complete framework of Hawkes processes with a Gamma density excitation function (i.e. estimation, simulation, goodness-of-fit) instead of an exponential-decaying function and we demonstrate some mathematical properties (i.e. expectation, variance) about the transient regime of the process. We illustrate our results with real insurance data about natural disasters in Luxembourg.

Non-terrestrial networks (NTNs) traditionally have certain limited applications. However, the recent technological advancements and manufacturing cost reduction opened up myriad applications of NTNs for 5G and beyond networks, especially when integrated into terrestrial networks (TNs). This article comprehensively surveys the evolution of NTNs highlighting their relevance to 5G networks and essentially, how it will play a pivotal role in the development of 6G ecosystem. We discuss important features of NTNs integration into TNs and the synergies by delving into the new range of services and use cases, various architectures, technological enablers, and higher layer aspects pertinent to NTNs integration. Moreover, we review the corresponding challenges arising from the technical peculiarities and the new approaches being adopted to develop efficient integrated ground-air-space (GAS) networks. Our survey further includes the major progress and outcomes from academic research as well as industrial efforts representing the main industrial trends, field trials, and prototyping towards the 6G networks.

We construct a recommendation system for car insurance, to allow agents to optimize up-selling performances, by selecting customers who are most likely to subscribe an additional cover. The originality of our recommendation system is to be suited for the insurance context. While traditional recommendation systems, designed for online platforms (e.g. e-commerce, videos), are constructed on huge datasets and aim to sug- gest the next best offer, insurance products have specific properties which imply that we must adopt a different approach. Our recommendation system combines the XGBoost algorithm and the Apriori algorithm to choose which customer should be recommended and which cover to rec- ommend, respectively. It has been tested in a pilot phase of around 150 recommendations, which shows that the approach outperforms standard results for similar up-selling campaigns. Recommendation system Up-selling Car insurance XGBoost algorithm Apriori algorithm

Interoperability has become a crucial value in European e-government developments, as promoted by the Digital Single Market strategy and the Tallinn Declaration. The European Union and its Member States have made considerable investments in improving the understanding of interoperability and in developing interoperable building blocks to support cross-border data exchange and public service provisioning. This includes recent updates of the European Interoperability Framework (EIF) and European Interoperability Reference Architecture (EIRA), as well as the publication of a number of generic and domain specific architecture and solutions building blocks such as digital identification or electronic delivery services. While in the previous version of the EIF, interoperability governance was not clearly developed, the new version of 2017 puts interoperability governance as a concept that spans across the different interoperability layers (legal, organizational, semantic and technical) and that builds the frame for interoperability overall. In this paper, we develop a definition of interoperability governance from a literature review and we put forward a model to investigate interoperability governance models at European and Member State levels. Based on several case studies of EU institutions and Member States, we could draw recommendations for what the key aspects of interoperability governance are to successfully diffuse interoperability into public service provisioning.