Ventspils University College

In this article, a number of smoothing methods were investigated to enhance the signal-to-noise (S/N) ratio of diverse methanol maser spectral data, encompassing variations in signal strength, multiplicity of peaks, and spectral complexity. The study aimed to improve the accuracy and reliability of astronomical measurements obtained with Irbene radio telescopes RT-16 and RT-32 at the Ventspils International Radio Astronomy Center. Comparing eleven different smoothing techniques, including moving average, Gaussian, Hanning, among others, the Savitzky–Golay smoothing method is identified as the optimal choice. The evaluation criteria included the preservation of spectral features, reduction of noise artifacts, and enhancement of S/N ratio metrics. The Savitzky–Golay method outperformed other techniques by effectively balancing noise reduction with the preservation of spectral details crucial for maser emission analysis.

High‐speed electron flows (HSEFs) play a crucial role in the energy dissipation and conversion processes within the terrestrial magnetosphere and can drive various types of plasma waves and instabilities, affecting the electron‐scale dynamics. The existence, spatial distribution, and general properties of HSEFs in the Earth magnetotail are still unknown. In this study, we conduct a comprehensive survey of HSEFs in the Earth magnetotail, utilizing NASA's Magnetospheric Multiscale (MMS) mission observations from 2017 to 2021. A total of 642 events characterized by electron bulk speeds exceeding 5,000 km/s are identified. The main statistical properties are: (a) The duration of almost all HSEFs are less than 4 s, and the average duration is 0.74 s. (b) HSEFs exhibit a strong dawn‐dusk (30%–70%) asymmetry. (c) 39.6%, 29.0%, and 31.4% of the events are located in the plasma sheet, plasma sheet boundary layer (PSBL), and lobe region, respectively. (d) In the plasma sheet, HSEFs have arbitrary moving directions regarding the ambient magnetic field, and the events near the neutral line predominantly move along the same direction as the ion outflows, indicating outflow electrons generated by magnetic reconnection. (e) HSEFs in the PSBL and lobe mainly move along the ambient magnetic field, and 70% of HSEFs in the PSBL exhibit features of reconnection inflow. The HSEFs in lobe regions may locate near the reconnection electron edges. Our study reveals that the HSEFs in magnetotail are closely associated with magnetic reconnection, and the statistical results deepen the understanding of HSEF fundamental properties in collisionless plasma.

We use the Magnetospheric Multiscale mission to study electron kinetic entropy across Earth's quasi‐perpendicular bow shock. We perform a statistical study of how the change in electron entropy depends on the different plasma parameters associated with a collisionless shock crossing. The change in electron entropy exhibits strong correlations with upstream electron plasma beta, Alfvén Mach number, and electron thermal Mach number. We investigate the source of entropy generation by correlating the change in electron entropy across the shock to the measured electric and magnetic field wave power strengths for different frequency intervals within different regions in the shock transition layer. The electron entropy change is observed to be greater for higher electric field wave power within the shock ramp and shock foot for frequencies between the lower hybrid frequency and electron cyclotron frequency, suggesting electrostatic waves are important for electron kinetic entropy generation at Earth's quasi‐perpendicular bow shock. Any eventual cross‐shock potential contribution to the electron entropy generation has not been considered in this study.

This paper presents the results of numerical simulations examining the thermodynamic processes during hydraulic hydrogen compression, using COMSOL Multiphysics® 6.0. These simulations focus on the application of hydrogen compression systems, particularly in hydrogen refueling stations. The computational models employ the CFD and heat transfer modules, along with deforming mesh technology, to simulate gas compression and heat transfer dynamics. The superposition method was applied to simplify the analysis of hydrogen and liquid piston interactions within a stainless-steel chamber, accounting for heat exchange between the hydrogen, the oil (working fluid), and the cylinder walls. The study investigates the effects of varying compression stroke durations and initial hydrogen pressures, providing detailed insights into temperature distributions and energy consumption under different conditions. The results reveal that the upper region of the chamber experiences significant heating, highlighting the need for efficient cooling systems. Additionally, the simulations show that longer compression strokes reduce the power requirement for the liquid pump, offering potential for optimizing system design and reducing equipment costs. This study offers crucial data for enhancing the efficiency of hydraulic hydrogen compression systems, paving the way for improved energy consumption and thermal management in high-pressure applications.

The Radio & Plasma Wave Investigation (RPWI) onboard the ESA JUpiter ICy moons Explorer (JUICE) is described in detail. The RPWI provides an elaborate set of state-of-the-art electromagnetic fields and cold plasma instrumentation, including active sounding with the mutual impedance and Langmuir probe sweep techniques, where several different types of sensors will sample the thermal plasma properties, including electron and ion densities, electron temperature, plasma drift speed, the near DC electric fields, and electric and magnetic signals from various types of phenomena, e.g., radio and plasma waves, electrostatic acceleration structures, induction fields etc. A full wave vector, waveform, polarization, and Poynting flux determination will be achieved. RPWI will enable characterization of the Jovian radio emissions (including goniopolarimetry) up to 45 MHz, has the capability to carry out passive radio sounding of the ionospheric densities of icy moons and employ passive sub-surface radar measurements of the icy crust of these moons. RPWI can also detect micrometeorite impacts, estimate dust charging, monitor the spacecraft potential as well as the integrated EUV flux. The sensors consist of four 10 cm diameter Langmuir probes each mounted on the tip of 3 m long booms, a triaxial search coil magnetometer and a triaxial radio antenna system both mounted on the 10.6 m long MAG boom, each with radiation resistant pre-amplifiers near the sensors. There are three receiver boards, two Digital Processing Units (DPU) and two Low Voltage Power Supply (LVPS) boards in a box within a radiation vault at the centre of the JUICE spacecraft. Together, the integrated RPWI system can carry out an ambitious planetary science investigation in and around the Galilean icy moons and the Jovian space environment. Some of the most important science objectives and instrument capabilities are described here. RPWI focuses, apart from cold plasma studies, on the understanding of how, through electrodynamic and electromagnetic coupling, the momentum and energy transfer occur with the icy Galilean moons, their surfaces and salty conductive sub-surface oceans. The RPWI instrument is planned to be operational during most of the JUICE mission, during the cruise phase, in the Jovian magnetosphere, during the icy moon flybys, and in particular Ganymede orbit, and may deliver data from the near surface during the final crash orbit.

The progress of modern electronics largely depends on the discovery and use of new materials with unique properties. One of such promising materials is carbon nanotubes. Their outstanding mechanical, thermal, and electrical properties open up new possibilities for creating small-sized electronic devices and improving the characteristics of existing materials by improving their manufacturing and processing technologies. One of the unique features of carbon nanotubes is their ability to encapsulate other atoms or molecules within their structure. This property can be used to create nanocontainers capable of protecting and transporting active substances or to change the electronic properties of nanotubes depending on the encapsulated substance. In this work, crystals of alkali metal iodides MI were encapsulated in carbon nanotubes with different structures and characteristics. The results obtained in terms of energy and density spectra of the state indicate the characteristics of conductivity due to an increase in energy and high peaks in the Fermi level. Thus, carbon nanotubes represent an important material for future developments in the field of nanoelectronics and nanotechnology.

A log data analysis plays an important role in the uranium mining process. Automating this analysis using machine learning methods improves the results and reduces the influence of the human factor. In particular, the identification of reservoir oxidation zones (ROZs) using machine learning allows a more accurate determination of ore reserves, and correct lithological classification allows the optimization of the mining process. However, training and tuning machine learning models requires labeled datasets, which are hardly available for uranium deposits. In addition, in problems of interpreting logging data using machine learning, data preprocessing is of great importance, in other words, a transformation of the original dataset that allows improving the classification or prediction result. This paper describes a uranium well log (UWL) dataset generated with the employment of floating data windows and designed to solve the problems of identifying ROZ and lithological classification (LC) on sandstone-type uranium deposits. Comparative results of the ways of solving these problems using classical machine learning methods and ensembles of machine learning algorithms are presented. It has been shown that an increase in the size of the floating data window can improve the quality of ROZ classification by 7–9% and LC by 6–12%. As a result, the best-quality indicators for solving these problems were obtained, f1_score_macro = 0.744 (ROZ) and accuracy = 0.694 (LC), using the light gradient boosting machine and extreme gradient boosting, respectively.

Electromagnetic Ion Cyclotron (EMIC) waves mediate energy transfer from the solar wind to the magnetosphere, relativistic electron precipitation, or thermalization of the ring current population, to name a few. How these processes take place depends on the wave properties, such as the wavevector and polarization. However, inferring the wavevector from in‐situ measurements is problematic since one needs to disentangle spatial and time variations. Using 8 years of Magnetospheric Multiscale (MMS) mission observations in the dayside magnetosphere, we present an algorithm to detect proton‐band EMIC waves in the Earth's dayside magnetosphere, and find that they are present roughly 15% of the time. Their normalized frequency presents a dawn‐dusk asymmetry, with waves in the dawn flank magnetosphere having larger frequency than in the dusk, subsolar, and dawn near subsolar region. It is shown that the observations are unstable to the ion cyclotron instability. We obtain the wave polarization and wavevector by comparing Single Value Decomposition and Ampere methods. We observe that for most waves the perpendicular wavenumber (k⊥) is larger than the inverse of the proton gyroradius (ρi), that is, k⊥ρi > 1, while the parallel wavenumber is smaller than the inverse of the ion gyroradius, that is, k‖ρi < 1. Left‐hand polarized waves are associated with small wave normal angles (θBk < 30°), while linearly polarized waves are associated with large wave normal angles (θBk > 30°). This work constitutes, to our knowledge, the first attempt to statistically infer the full wavevector of proton‐band EMIC waves observed in the outer magnetosphere.

Macroscopic wave and oscillatory phenomena ubiquitously detected in the plasma of the corona of the Sun are interpreted in terms of magnetohydrodynamic theory. Fast and slow magnetoacoustic waves are clearly distinguished in observations. Properties of coronal magnetohydrodynamic waves are determined by local parameters of the plasma, including the field-aligned filamentation typical for the corona. It makes coronal magnetohydrodynamic waves reliable probes of the coronal plasma structures by the method of magnetohydrodynamic seismology. For example, propagating slow waves indicate the local direction of the guiding magnetic field. Standing, sloshing and propagating slow waves can be used for probing the coronal heating function and the polytropic index. Kink oscillations of coronal plasma loops provide us with estimations of the absolute value of the magnetic field in oscillating plasma loops. This tutorial introduces several techniques of magnetohydrodynamic seismology of solar coronal plasmas. It includes the description of practical steps in the data acquisition, pre-processing, and processing using the open-access data of the Atmospheric Imaging Assembly on the Solar Dynamics Observatory spacecraft, and elaborated data analysis techniques of motion magnification and Bayesian statistics.

The electric solar wind sail, or E-sail, is a propellantless interplanetary propulsion system concept. By deflecting solar wind particles off their original course, it can generate a propulsive effect with nothing more than an electric charge. The high-voltage charge is applied to one or multiple centrifugally deployed hair-thin tethers, around which an electrostatic sheath is created. Electron emitters are required to compensate for the electron current gathered by the tether. The electric sail can also be utilised in low Earth orbit, or LEO, when passing through the ionosphere, where it serves as a plasma brake for deorbiting—several missions have been dedicated to LEO demonstration. In this article, we propose the ESTCube-LuNa mission concept and the preliminary cubesat design to be launched into the Moon’s orbit, where the solar wind is uninterrupted, except for the lunar wake and when the Moon is in the Earth’s magnetosphere. This article introduces E-sail demonstration experiments and the preliminary payload design, along with E-sail thrust validation and environment characterisation methods, a cis-lunar cubesat platform solution and an early concept of operations. The proposed lunar nanospacecraft concept is designed without a deep space network, typically used for lunar and deep space operations. Instead, radio telescopes are being repurposed for communications and radio frequency ranging, and celestial optical navigation is developed for on-board orbit determination.

As a large social structure, the health care system is often reflected in media publications. This creates a significant impact on society’s attitude towards the system and the state in general. In order to predict and correct state policies, media actions, and identify media shortcomings, it is necessary to analyze the image portrayed by the media and the public’s attitude towards it. In this article, we present the results of a multidirectional analysis of a corpus of media publications related to health care. We propose a method for analyzing the information image of health care formed by the mass media based on a topic model of a text corpus. The method evaluates reader interest in various healthcare topics, the dynamics of changes in publication sentiment, and the main information trends. The article presents the results of analyzing a corpus of mass media publications in Kazakhstan from January 2020 to January 2023.

Plain Language Summary Collisionless shock waves are an important source of accelerating electrons up to cosmic ray energies throughout our universe. Common electron acceleration mechanisms, explaining the highly relativistic energies observed in cosmic rays, require a population of pre‐accelerated electrons up to mildly relativistic energies of around 0.1–1 MeV. This is known as the electron injection problem and a lot of research is currently spent on studying this pre‐acceleration phase of electron acceleration. We use spacecraft data from the Magnetospheric Multiscale mission to study an electron acceleration mechanism able to accelerate electrons from typical solar wind energies of 20 eV up to around 100 keV. One of the most promising theories for explaining electron acceleration is the so‐called stochastic drift acceleration theory, which involves electron interaction with plasma waves forming within a shock. We provide additional observational evidence supporting this theory.

The article investigates sustainable development from the holistic perspective, taking into account the complex nature of the world and the dynamism of the socio-economic systems. The study is interdisciplinary, as it addresses the issues of economics, mathematics and physics with the main focus on the modern perspective of sustainable development offered in the field of education. The article focuses on key questions concerning the expansion of the educational processes and deepening of ideas and knowledge about the dynamism and diversity of the planetary system. The holistic approach implies the interaction of various nonlinear features that have been used in the paper to build a mental model and a causal relationship schema. The understanding of the interaction of energy flows in socio-economic systems has been used by the authors to explain the underlying connection of various processes. The authors of the article propose a systemic dynamic model of sustainability, which can open up an understanding of some of the reasons for changes in the potential of the industrial sector. Modeling results have been obtained and interpreted using historical USA statistical data from 1949 to 2019. In the article, the authors reveal the relationship between nature, society and human from the point of view of promising and methodological approaches of the “new” and “old” world. The diversity of experiences makes it possible to question the dominant approaches of traditional teaching in education. This creates the need to look for new foundations that can promote the development of more sustainable learning for the future.

In order to search for new 6.035 GHz excited OH masers 272 star-forming regions visible from the northern hemisphere with known active methanol masers were observed with the 32 m and 16 m radio telescopes of the Ventspils International Radio Astronomy Center (VIRAC). Three possibly new excited OH maser sources at 6.035 GHz were seen.

Terminology work requires a lot of manual processing, especially extracting data from materials that have not been digitized, so more efficient solutions and tools are necessary to improve the efficiency of the research. Since 2021, a team of terminologists, translators, researchers, information system developers worked together, during which the new open-access interactive multifunctional information management system was designed and developed for data storage and a wide range of statistical and search options especially for language research purposes and comparative multilingual studies in linguistics. The information system consists of multiple modules, which are successfully designed and developed and have been effectively used by researchers during the period of August 2021—July 2023 for entering, collection and retrieval data for special lexis research.

Objective – The current paper investigates the role of creating public and private goods through aviation to determine state policy priorities and analyse the aviation industry's impact on the national economy in Latvia. Methodology – The current paper involves a multi-factorial approach, combining legal, economic, and social impact assessment elements. The quantitative analysis applies an input-output model to assess the aviation industry's direct, indirect, inducted, and catalytic effects. Findings – The assessment of multi-factorial indicators assumes paramount importance in ascertaining the contribution of the Latvian aviation sector to the nation's gross domestic product (GDP). Despite its immersion within an intensely competitive market environment, the aviation sector continues to witness substantial government interventions on a global scale. Thus, it becomes imperative to delineate the considerations that delineate public goods, ensuring their alignment with the tenets of equitable competition. Novelty – Compared to previous studies, the input-output analysis in the aviation industry is extended to evaluate the public and private goods created by the aviation industry to determine favourable state aid policies. Type of Paper: Empirical JEL Classification: D71; H11 Keywords: Aviation, Input-Output Model, State Aid, State Policy, Public Goods. Reference to this paper should be made as follows: Kokars, A.; Sergejs, H. (2023). Strategic Development of Aviation in Latvia, J. Bus. Econ. Review, 8(3), 76–88. https://doi.org/10.35609/jber.2023.8.3(2)

Monitoring of the water level and river discharge is an important task, necessary both for assessment of water supply in the current season and for forecasting water consumption and possible prevention of catastrophic events. A network of ground hydrometric stations is used to measure the water level and consumption in rivers. Rivers located in sparsely populated areas in developing countries of Central Asia have a very limited hydrometric network. In addition to the sparse network of stations, in some cases remote probing data (virtual hydrometric stations) are used, which can improve the reliability of water level and discharge estimates, especially for large mountain rivers with large volumes of suspended sediment load and significant channel instability. The aim of this study is to develop a machine learning model for remote monitoring of water levels in the large transboundary (Kazakhstan-People’s Republic of China) Ili River. The optical data from the Sentinel-2 satellite are used as input data. The in situ (ground-based) data collected at the Ili-Dobyn gauging station are used as target values. Application of feature engineering and ensemble machine learning techniques has achieved good accuracy of water level estimation (Nash–Sutcliffe model efficiency coefficient (NSE) >0.8). The coefficient of determination of the model results obtained using cross-validation of random permutations is NSE = 0.89. The method demonstrates good stability under different variations of input data and ranges of water levels (NSE > 0.8). The average absolute error of the method ranges from 0.12 to 0.18 meters against the background of the maximum river water level spread of more than 4 meters. The obtained result is the best current result of water level prediction in the Ili River using the remote probing data and can be recommended for practical use for increasing the reliability of water level estimation and reverse engineering of data in the process of river discharge monitoring.

The highly-filamented nature of the coronal plasma significantly influences dynamic processes in the corona such as magnetohydrodynamic waves and oscillations. Fast magnetoacoustic waves, guided by coronal plasma non-uniformities, exhibit strong geometric dispersion, forming quasi-periodic fast-propagating (QFP) wave trains. QFP wave trains are observed in extreme-ultraviolet imaging data and indirectly in microwaves and low-frequency radio, aiding in understanding the magnetic connectivity, energy, and mass transport in the corona. However, measuring the field-aligned group speed of QFP wave trains, as a key parameter for seismological analysis, is challenging due to strong dispersion and associated rapid evolution of the wave train envelope. We demonstrate that the group speed of QFP wave trains formed in plane low-β coronal plasma non-uniformities can be assessed through the propagation of the wave train’s effective centre of mass, referred to as the wave train’s centroid speed. This centroid speed, as a potential observable, is shown empirically to correspond to the group speed of the most energetic Fourier harmonic in the wave train. The centroid speed is found to be almost insensitive to the waveguide density contrast with the ambient corona, and to vary with the steepness of the transverse density profile. The discrepancy between the centroid speed as the group speed measure and the phase speed at the corresponding wavelength is shown to reach 70%, which is crucial for the energy flux estimation and interpretation of observations.