STRATEGY OF PUBLIC-PRIVATE PARTNERSHIPS DEVELOPMENT IN CRISIS

The role of strategy of public-private partnerships development through information is examined. The informational nature measures, the implementation of which help to promote Ukrainian innovative products on foreign markets, are identified. The urgency of implementing the strategy of public-private partnerships to intensify foreign trade with innovative products in crisis period is substantiated

Light scattering from volcanic-sand particles in deposited and aerosol form

The light-scattering properties of volcanic sand collected in Iceland are studied here to characterize the sand particles and develop a reference for future remote-sensing observations. While such sand is common in Iceland, the smaller-size fraction can be readily transported by winds and found in the atmosphere at distant locations. The sand appears dark when deposited on a surface due to the high optical absorption of the material. Therefore, atmospheric regions containing such particles during a dust storm may absorb sunlight considerably, causing redistribution of solar energy. Here, we measure the angular scattered-light intensity and degree of linear polarization from the sand. This is done with two experimental apparatuses, the Cosmic Dust Laboratory (CoDuLab) at the Institute de Astrofísica de Andalucía (IAA) and the goniospectropolarimeter (FIGIFIGO) at the Finnish Geospatial Research Institute (FGI). Two scattering-scenarios of practical interest for remote-sensing applications are considered: (1) single sand-particles suspended in aerosol as an optically thin cloud, and (2) the same particles deposited on a substrate. We also model the measurements with the discrete dipole approximation to estimate the complex-valued refractive index m, where we find that m ≈ 1.6 + 0.01i at λ = 647 nm. Lastly, we present a comparative analysis of the polarimetric response of the sand particles with that reported in the literature for carbon-soot, another highly absorbing atmospheric contaminant.Peer reviewe

Photometric modelling for laboratory measurements of dark volcanic sand

We have performed laboratory measurements of the bidirectional reflectance factor (BRF) of a sample of dark volcanic sand. The measurements were carried out with three different treatments of the sample to produce different porosity and roughness characteristics. We model the measured BRF with a semi-numerical scattering model for particulate media, meant especially for dark planetary regoliths. We compare the BRF in two different spectral bands, 500-600 nm and 800-900 nm. The particulate medium (PM). scattering model is found to fit the measured data well, with a phase function representing the differences between the spectral bands. The interpretation of the physical parameters of the PM model is qualitatively sound, but remains somewhat uncertain due in part to the difficulty of characterizing the measured sample. (C) 2016 Elsevier Ltd. All rights reserved.Peer reviewe

Metsahovi Radio Observatory - IVS Network Station

In 2012, Metsahovi Radio Observatory together with Finnish Geodetic Institute officially became an IVS Network Station. Eight IVS sessions were observed during the year. Two spacecraft tracking and one EVN X-band experiment were also performed. In 2012, the Metsahovi VLBI equipment was upgraded with a Digital Base Band Converter, a Mark 5B+, a FILA10G, and a FlexBuff

Mitigating the effect of source structure in geodetic VLBI by re-weighting observations using closure delays and baseline-to-jet orientation

An ideal target for geodetic very long baseline interferometry (VLBI) is a strong and point-like radio source. In reality, most celestial sources used in geodetic VLBI have spatial structure. This is as a major source of error in VLBI Global Observing System (VGOS) and also affects legacy S/X observations. Source structure causes a systematic delay, which can affect the geodetic estimates if not modelled or otherwise accounted for. In this work, we aim to mitigate its impact by extending the stochastic model used in the least-squares fitting of the VLBI group delays. We have developed a weighting scheme to re-weight the observations by parameterizing the source structure component in terms of closure delays and jet orientation relative to the observing baseline. It was implemented in the Vienna VLBI Software. To assess the performance of the extended stochastic model, we analysed the CONT17 legacy sessions and generated suitable reference solutions for comparison. The effects of re-weighting were evaluated with respect to the session fit statistics, source-wise residuals, and geodetic parameters. We find that this relatively simple noise model consistently improves the session fit by about 5% with moderate variation from session to session. The geodetic estimates are not affected to a significant level by this new weighting method. Source-wise we see improved post-fit residuals for 63 out of a total of 91 sources observed

Evidence of the Gaia-VLBI position differences being related to radio source structure

We report the relationship between the Gaia--VLBI position differences and the magnitudes of source structure effects in VLBI observations. Because the Gaia--VLBI position differences are statistically significant for a considerable number of common sources, we attempt to discuss and explain these position differences based on VLBI observations and available source images at cm-wavelengths. Based on the derived closure amplitude root-mean-square (CARMS), which quantifies the magnitudes of source structure effects in the VLBI observations used for building the third realization of the International Celestial Reference Frame, the arc lengths and normalized arc lengths of the position differences are examined in detail. The radio jet directions and the directions of the Gaia--VLBI position differences are investigated for a small sample of sources. Both the arc lengths and normalized arc lengths of the Gaia and VLBI positions are found to increase with the CARMS values. The majority of the sources with statistically significant position differences are associated with the sources having extended structure. Radio source structure is the one of the major factors of these position differences, and it can be the dominate factor for a number of sources. The vectors of the Gaia and VLBI position differences are parallel to the radio-jet directions, which is confirmed with stronger evidence.Peer reviewe

Imaging VGOS Observations and Investigating Source Structure Effects

Funding Information: This research has made use of the Generic Mapping Tools package, the pgplot library, and the SAO/NASA Astrophysics Data System. This research has made use of data from the MOJAVE database that is maintained by the MOJAVE team (Lister et al., 2018 ). This research was supported by the Academy of Finland project No. 315721. Susanne Lunz is supported by the DFG Grant No. HE5937/2‐2. Funding Information: We would like to thank the two reviewers Sergei Bolotin and Arthur Niell for their helpful comments. The results reported in this study used the data owned by the International VLBI Service (IVS) and its international self-funded member organizations. We are grateful to the IVS VGOS stations at GGAO (MIT Haystack Observatory and NASA GSFC, USA), Ishioka (Geospatial Information Authority of Japan), Kokee Park (U.S. Naval Observatory and NASA GSFC, USA), McDonald (McDonald Geodetic Observatory and NASA GSFC, USA), Onsala (Onsala Space Observatory, Chalmers University of Technology, Sweden), Westford (MIT Haystack Observatory), Wettzell (Bundesamt f?r Kartographie und Geod?sie and Technische Universit?t M?nchen, Germany), and Yebes (Instituto Geogr?fico Nacional, Spain), to the staff at the MPIfR/BKG correlator center and the MIT Haystack Observatory correlator for performing the correlations and the fringe fitting of the data, to the NASA GSFC VLBI group for doing the geodetic solutions, and to the IVS Data Centers at BKG (Leipzig, Germany), Observatoire de Paris (France), and NASA CDDIS (Greenbelt, MD, USA) for the central data holds. Publisher Copyright: © 2021. The Authors.The next-generation, broadband geodetic very long baseline interferometry system, named VGOS, is being developed globally with an aim to achieve 1 mm accuracy for station positions. Currently, the systematic errors in VGOS broadband delays are still about 20 ps. In this study, we demonstrate that it is feasible to make images directly from VGOS observations without the need of complicated calibrations and determine the source structure effects in VGOS broadband delays through the process of model fitting to the structure phases from our imaging results. Source structure effects are investigated in detail, and it is shown that the systematic errors in VGOS observations are well explained by these effects. For instance, the root-mean-square (RMS) closure delays of the observations of sources 0016 + 731 and 1030 + 415 are 24.9 and 50.2 ps in session VO0034, respectively; after correcting source structure effects based on the images, the RMS values of the residual closure delays are 5.5 and 10.1 ps. The jumps in delay observables with magnitudes of several hundreds of picoseconds are found to be caused by 2π phase shifts among the four bands due to strong source structure effects. The impact of the alignment of the images at the four frequency bands in VGOS is discussed. Our study provides a methodology for deriving images of radio sources at the four bands of VGOS observations and discusses the alignment of the images at the four bands, which is fundamental to mitigating these systematic effects.Peer reviewe