EXPERIMENTAL DEVICE FOR RESEARCHING THE TECHNOLOGY OF ANCHOR-CABLE MOVERS POSITIONING

The features of the design of the experimental device with an anchor-cable propulsion unit are considered. An algorithm for discrete interaction with soil is synthesized. Determination of the features of the hardware implementation of the control system.

The composition of edible oils modifies β-sitosterol/γ-oryzanol oleogels part II: Addition of selected minor oil components

The first part of this study showed that the triglyceride composition of purified oils has little impact on sterol/sterol ester oleogels. Hence, changes in the gels’ properties observed in previous studies must arise from minor polar components, particularly by changing the interactions within the fibrillar network. Selected molecules (oleic acid, tocopheryl acetate, monoglycerides, and water) were added to three purified oils to unravel the individual contributions introduced by different functional groups. While all additives retarded the molecular self-assembly of sitosterol with oryzanol, distinct effects were found for gel hardness, transition temperatures and enthalpies, strain sweep responses, and microstructure. It was discovered that the maximum storage modulus in the linear viscoelastic region does not necessarily relate to the gels’ compression firmness. In samples comprising oleic acid and tocopheryl acetate, discrete interaction mechanisms with the scaffolding elements were suggested since results between the two additives developed differently and were dose-dependent. A network supporting effect was suggested at low concentrations, in line with previous results for oils comprising low levels of thermal deterioration products. The microstructure of oleogels was considerably modified with additives. Unfortunately, effects are difficult to quantify due to the packed surface observed in AFM micrographs.

Wave climate in the Black Sea: description and trend evaluation using new ECMWF-ERA5 reanalysis and wave-current interaction.

<p>This study analyzes the evolution of the wave climate in the Black Sea basin in a 31-year long hindcast (1988-2018) performed with the third-generation wave model WaveWatchIII v5.16, forced by the ECMWF-ERA5 reanalysis winds at 30km of spatial resolution and 1-hour frequency. The wave model is implemented on a grid covering the whole Black Sea, with 3km grid step and is off-line coupled with a NEMO based hydrodynamical model. The wave spectrum is discretized using 24 directional sectors, and 30 frequencies, with 10% increment starting from 0.055Hz. The model is implemented to solve deep water processes, following the WAM Cycle4 model physics, with Ultimate Quickest propagation scheme and GSE alleviation, which is implemented in WWIII. Wind input and dissipation are based on Ardhuin et al. (2010), wave-wave interactions are based on Discrete Interaction Approximation. Currents and air-sea temperature difference are provided to the wave model to account for Doppler shift and atmospheric stability above the sea. Model validation and statistical analysis have been carried out to describe the wave climate of the Black sea, considering the following wave fields: significant wave height (Hs), mean wave period (Tm) and mean wave direction. Statistics as Mean, Maximum, 5<sup>th</sup> percentile and 95<sup>th</sup> statistics have been computed to produce monthly climatologies. The work considers also the evaluation of trends for Hs and Tm, and the evaluation of tendency in the occurrence frequency of mean and max fields for Hs and Tm.</p><p>There is no evidence about an overall trend in Hs and Tm, but tendencies can be highlighted in some months and seasons. The most evident trend occurs in Summer on the whole wave spectrum, with reduction of Hs and Tm in the Eastern basin, and increasing in the South-Western basins. Even the evaluation of occurrence frequencies suggests that Black Sea is subjected to a change in the wave regime.</p>

The Fast Discrete Interaction Approximation Concept

Hasselmann and coauthors proposed the discrete interaction approximation (DIA) as the best tool replacing the nonlinear evolution term in a numerical wind–wave model. Much later, Polnikov and Farina radically improved the original DIA by means of location all the interacting four wave vectors, used in the DIA configuration, exactly at the nodes of the numerical frequency–angular grid. This provides a nearly two-times enhancement of the speed of numerical calculation for the nonlinear evolution term in a wind–wave model. For this reason, the proposed version of the DIA was called as the fast DIA (FDIA). In this paper, we demonstrate all details of the FDIA concept for several frequency–angular numerical grids of high-resolution with the aim of active implementation of the FDIA in modern versions of world-wide used wind–wave models.

The Fast Discrete Interaction Approximation Concept

Hasselmann and coauthors proposed the discrete interaction approximation (DIA) as the best tool replacing the nonlinear evolution term in a numerical wind-wave model. Much later, Polnikov and Farina radically improved the original DIA by means of location all the interacting four wave vectors, used in the DIA configuration, exactly at the nodes of the numerical frequency-angular grid. This provides nearly two-times enhancing the speed of numerical calculation for the nonlinear evolution term in a wind-wave model. For this reason, the proposed version of the DIA was called as the fast DIA (FDIA). In this paper we demonstrate all details of the FDIA concept for several frequency-angular numerical grids of high resolution, with the aim of active implementation the FDIA in modern versions of world-wide used wind-wave models.

Role of Nonlinear Four-Wave Interactions Source Term on the Spectral Shape

The goal of this paper is to investigate the importance of the four-wave nonlinear interactions (SNL4) on the shape of the power spectrum of ocean waves. To this end, the following results are discussed: a number of authors have conducted modern experimental measurements of ocean waves over the past decades and found that the measured power spectrum has (a) a very high central peak (characterized by the parameter γ, developed in the 1970s in the JONSWAP program) and (b) enhanced high-frequency channels which lead to the phenomenon of “bimodality”, also a well-known phenomenon. We discuss how a numerical hindcast of the Draupner storm (1995) with the standard code WAVEWATCH-III with full Boltzmann interactions also reflects these previously experimentally determined spectral shapes. Our results suggest that the use of the full Boltzmann interactions (as opposed to the discrete interaction approximation often employed for forecasting/hindcasting) is important for obtaining this characteristic physical spectral shape of the power spectrum.

Plasmonic nano-shells: atomistic discrete interaction versus classic electrodynamics models

Using the extended discrete interaction model and Mie theory, we investigate the tunability of the optical polarizability and show the size-dependence of the plasma frequency of small metallic nano-shells in the 1–15 nm size region.