Work at Graz on satellite signatures

The size and shape of the satellites retroreflector arrays have a major impact on the distribution and scatter of the return signal; this can be seen clearly when reaching sub-cm ranging accuracies and when using Single-Photon Detectors with single- or multi-photon returns; for other receiver systems (using MCP's), it should be checked also. As a consequence, the necessary center-of-mass correction for some satellites will differ, depending on the receiver systems. While this effect is not yet visible on small satellites or small retro-reflector arrays (like STARLETTE, ERS1), it can be in the order of centimeters on AJISAI or ETALON

Sub-cm ranging and other improvements in Graz

A lot of tests and experiments have been made in Graz during the last 2 years to increase performance and accuracy; using the SPAD from the Prag group as receiver, we have reached now about 5 mm RMS from the calibration target, and about 8 mm RMS from ERS1 and STARLETTE. In addition, by routinely using the semitrain, the number of returns has been increased significantly for most satellites

Consensual (Design) Fictions: co-creating iterative use cases to define technology conceptualization

Design Fiction has become the basic tool with which a team of European institutions has addressed the definition of use cases for the project of a future social network called HELIOS. This article aims to showcase this experience of technological conceptualization that has used a co-creation process of speculative figurations as a methodological resource. The underlying HELIOS project-funded by the EU through the H2020 program [http://heliossocial.eu]- is a proposal for a decentralized social platform. It proposes an alternative to existing networks because of its context awareness and its connectivity based on trust and transparency. Key findings of this practice-based research show a proto-toolkit on how collaborative fictional narratives are useful in innovation processes. Moreover, it presents a procedure to deal with the complexity of not-yet-existing technologies and socio-technical scenarios. The article highlights some challenges to add ethical, political, and environmental concerns to the technology development process itself.Objectius de Desenvolupament Sostenible::10 - Reducció de les DesigualtatsObjectius de Desenvolupament Sostenible::12 - Producció i Consum ResponsablesObjectius de Desenvolupament Sostenible::9 - Indústria, Innovació i InfraestructuraPostprint (author's final draft

Evaluating Posts on the Steemit Blockchain: Analysis on Topics Based on Textual Cues

Online Social Networking platforms (OSNs) are part of the people's everyday life answering the deep-rooted need for communication among humans. During recent years, a new generation of social media based on blockchain became very popular, bringing the power of the technology to the service of social networks. Steemit is one such and employs the blockchain to implement a rewarding mechanism, adding a new, economic, layer to the social media service. The reward mechanism grants virtual tokens to the users capable of engaging other users on the platform, which can be either vested in the platform for increased influence or exchanged for fiat currency. The introduction of an economic layer on a social networking platform can seriously influence how people socialize. In this work, we tackle the problem of understanding how this new business model conditions the way people create contents. We performed term frequency and topic modelling analyses over the written contents published on the platforms between 2017 and 2019. This analysis lets us understand the most common topics of the contents that appear in the platform. While personal mundane information still appears, along with contents related to arts, food, travels, and sport, we also see emerging a very strong presence of contents about blockchain, cryptocurrency and, more specifically, on Steemit itself and its users

Effects related to deposition temperature of ZnCoO films grown by Atomic Layer Deposition - uniformity of Co distribution, structural, optical, electrical and magnetic properties

In the present study we report on properties of ZnCoO films grown at relatively low temperature by the Atomic Layer Deposition, using two reactive organic zinc precursors (dimethylzinc and diethylzinc). The use of these precursors allowed us the significant reduction of a growth temperature to below 300oC. The influence of growth conditions on the Co distribution in ZnCoO films, their structure and magnetic properties was investigated using Secondary Ion Mass Spectroscopy, Scanning Electron Microscopy, Cathodoluminescence, Energy Dispersive X-ray Spectrometry (EDX), X-ray diffraction and Superconducting Quantum Interference Device magnetometry. We achieved high uniformity of the films grown at 160{\deg}C. Such films are paramagnetic. Films grown at 200{\deg} and at higher temperature are nonuniform. Formation of foreign phases in such films was detected using high resolution EDX method. These samples are not purely paramagnetic and show weak ferromagnetic response at low temperature.Comment: 9 pages, 6 figures, 18 reference

The first satellite laser echoes recorded on the streak camera

The application of the streak camera with the circular sweep for the satellite laser ranging is described. The Modular Streak Camera system employing the circular sweep option was integrated into the conventional Satellite Laser System. The experimental satellite tracking and ranging has been performed. The first satellite laser echo streak camera records are presented

Interpersonal Trust within Social Media Applications: A Conceptual Literature Review

Interpersonal trust within social media applications is a highly discussed topic. The debate ranges from trusting the application, related to security and privacy, to trusting content and the underlying content delivery algorithms. Several trust-related phenomena have surfaced in recent years, known as filter bubbles, echo chambers and fake news. Addressing these phenomena is often pushed to either the regulator or directly to the provider of the social media application. Interpersonal trust within social media applications is a more complex topic and not limited to the application or the content, but has to include the behaviour of the user. To broaden the debate beyond the prevalent focus on the application and content this paper presents a conceptual literature review studying interpersonal trust within social media with the goal to deepen the understanding of the complex interplay between user behaviour in relation to interpersonal trust. Based on this review modalities of interpersonal trust are identified and presented. To extend on these findings an information-dense word embedding based analysis is presented by using unsupervised machine learning techniques

Incorporation of cobalt into ZnO nanoclusters

The structural, optical and magnetic properties of nanostructured ZnO films co-doped with cobalt and aluminium have been studied. The nanocrystalline films, with cluster sizes in range 50 - 100 nm, were deposited by pulsed laser ablation in a mixed atmosphere of oxygen and helium. The nanocrystallites have the wurtzite structure and are highly oriented with the c-axis perpendicular to the substrate. Both optical and electron spin resonance (ESR) spectroscopy results show the substitutional incorporation of Co$^{2+}$ ions on the Zn site inside the ZnO nanoclusters. The temperature dependence of the ESR spectra follows Curie law corresponding to a paramagnetic material

Two wavelength satellite laser ranging using SPAD

When ranging to satellites with lasers, there are several principal contributions to the error budget: from the laser ranging system on the ground, from the satellite retroarray geometry, and from the atmosphere. Using a single wavelength, we have routinely achieved a ranging precision of 8 millimeters when ranging to the ERS-1 and Starlette satellites. The systematic error of the atmosphere, assuming the existing dispersion models, is expected to be of the order of 1 cm. Multiple wavelengths ranging might contribute to the refinement of the existing models. Taking into account the energy balance, the existing picosecond lasers and the existing receiver and detection technology, several pairs or multiple wavelengths may be considered. To be able to improve the atmospheric models to the subcentimeter accuracy level, the differential time interval (DTI) has to be determined within a few picoseconds depending on the selected wavelength pair. There exist several projects based on picosecond lasers as transmitters and on two types of detection techniques: one is based on photodetectors, like photomultipliers or photodiodes connected to the time interval meters. Another technique is based on the use of a streak camera as an echo signal detector, temporal analyzer, and time interval vernier. The temporal analysis at a single wavelength using the streak camera showed the complexity of the problem