Volume 59 (2022): Edizione 6 (December 2022)

In this research, density functional theory accompanied with linear combination of atomic orbitals (LCAO) method is applied to study the atomic and electronic structure of wurtzite and rocksalt Zn_xMg_1−xO pseudobinary compounds in their bulk phases. Calculated band gaps of Zn_xMg_1−xO solid solutions under study are further validated by means of spectroscopic ellipsometry and optical absorption. In agreement with an experiment, it is predicted that increase of Zn content in Zn_xMg_1−xO leads to narrowing of its band gap for both wurtzite and rocksalt phases. The calculated infra-red (IR) spectra show that the IR peaks are shifted towards larger frequencies along with decrease of Zn content. Presence of imaginary phonon frequencies in rocksalt Zn_xMg_1−xO of x > 0.625 allows us to suggest that it is necessary to use properly oriented substrates for epitaxial growth to overcome polycrystallinity inZn_xMg_1−xO thin films at concentration x = 0.4 – 0.6.

It has been experimentally shown that in the isothermal mechanocycling of continuous cylindrical samples of saponite–titanium composites under conditions of a complex stress state, a reversible deformation of the properties of martensitic inelasticity is observed, which appears during thermal cycling at intervals of martensitic transformations.

According to the results of the experiment, the influence of the ratio between the static and cyclic components of the stress on the change of shear deformation in a complex stress state during mechanical cycling with axial load is estimated.

On 4 July 2022, a complex low-frequency solar radio burst was observed in Metsähovi Radio Observatory of Aalto University. The radio burst was observed at a frequency range between 20 and 80 MHz. In GOES (Geostationary Operational Environmental Satellite) class, the event was classified as C5.1. However, coronal mass ejection (CME) was not associated to this event. The observed radio burst was a long-lasting (~10 minutes) event, and it could be mainly classified as type II solar radio event. Also type III solar events were observed before long-lasting type II event. The event includes common frequency drifting emission structures, both fundamental and harmonic structures, but also rarely observed continuum-like or stationary structure. It is assumed that the continuum-like radio emission structure is originated from the stationary flare (coronal) loop, which was visible over the whole event. The drifting emission structure means accelerated electrons, which are produced by the shock related phenomena. The paper provides the observations from this event on radio wavelength, and also soft-X-ray regime and optical wavelength (AIA 171). In addition, a possible, simplified scenario is presented for forming the drifting and continuum solar radio emissions in type II solar burst.

Increase of energy efficiency is Latvia’s national priority and policy instrument that allows reducing consumption of energy and costs, increasing the safety level of energy supply and reducing dependence on import. One of the trends for reducing energy consumption is to increase energy performance of buildings. In compliance with the EU and Latvian political statements, it is required to promote renovation of residential and non-residential buildings.

Studies regarding energy performance aspects in the sector of non-residential buildings in Latvia are comparatively rare; however, non-residential buildings form a considerable part of the building stock, and the increase of their energy performance can bring a significant contribution in achieving the national targets.

The research analyses the sector of non-residential buildings, their characteristic statistical data, energy consumption and requirements of energy performance standards. To characterise this sector more comprehensively, information on energy performance certificates of buildings issued during the period from 2016 to 2021 has been evaluated, allowing to make general conclusions on the energy performance level of different non-residential buildings and provide proposals for trends to increase their energy efficiency.

The paper presents a new approach to energy indicator determination, such as specific fuel consumption and energy efficiency of the power plant. The essence of the new method is to determine the instantaneous power of the installation with subsequent data processing. The use of this method allows establishing the dependence of specific energy indicators on the generating unit load levels. The established distribution allows defining optimum parameters of experimental setup and consumption at various loading levels. The highest specific energy consumption of fuel is observed (1189–1297 g /(kW·h) and 962–1147 g / / kW·h)) at the lowest and the highest load for different fuels. Experimental data show that fuel without ethanol impurities can generate more electricity, which should be used at higher demand.

To make informed decisions, modern society, like modern business, must operate with adequate information about many complex interrelated aspects of its activities. Land use is only one of such aspects. Agricultural lands are of particular importance today. Land data are needed to analyse environmental processes, as well as end unsystematic, uncontrolled use of agricultural land, environmental degradation, destruction of important wetlands, loss of fish diversity and destruction of wildlife habitats. To solve these problems, it is advisable to conduct regular analysis and evaluation of land resources, justification and analysis of factors influencing the agricultural land market in the country. The tasks were solved using multidimensional statistical methods, in particular, factor analysis, which helped to get rid of subjectivity in the choice of factors influencing the market under study. Based on the model of influence of factors on the national market of agricultural land in Ukraine, six main factors were identified, the most influential of which were the components of agricultural development (first factor) and, to a lesser extent, the component of vegetable production and yield (fourth factor). The interrelationships and the degree of influence of the selected factors on the main indicators of the agricultural land market, namely, on the area of purchase and sale plots, the price of purchase and sale plots, and the number of transactions were also analysed.