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The paper proposes a method of simultaneous reconstruction of the electrical conductivity and magnetic permeability profiles of planar metal research objects based on the results of single measurements by eddy current probes using surrogate optimization techniques in a reduced compact subspace design and accumulating the full amount of the most important a priori information about the modes of electromagnetic objects. In addition to the information on the response of probe signals to changes in electrophysical parameters, a priori information includes the data on multifrequency sensing and changes in the lift-off between metal research objects and eddy current probes. All the main stages for the implementation of the method of solving the inverse problem are demonstrated, namely, creating a uniform computer quasi-design of the experiment with improved 2D-projections based on LPτ-Sobol's sequences; creating surrogate models on fully connected deep neural networks; reducing the dimensionality of the full design space using the principal components method of PCA; reconstructing profiles as a result of surrogate optimisation in a compact subspace. Numerical examples of the method are also presented in the paper. [ABSTRACT FROM AUTHOR]

Standards are critically important for smartening the grid because they affect the interoper-ability, compatibility, efficiency, and realisation of new technologies and services. In this paper we assess the contribution of EU funded Horizon 2020 projects to adapting or initiating new Smart Grid standards. We provide a comprehensive overview of the Smart Grid standardisation ecosystem and identify opportunities for researchers and innovators to participate in stan-dardisation activities. We identify 225 Horizon 2020 Smart Grid projects and explore which have contributed to the creation or revision of Smart Grid standards. We identify the type of standardisation activities undertaken and explore the factors that influence engagement. We have found that 21 % of EU Horizon 2020 Smart Grid projects engage in some level of standardisation activities. Of these projects the majority (60 %) are involved in understanding standards, 31 % actively engage in influencing standards, while 8 % successfully participate in elaborating new standards. Our study demonstrates that despite the complexity of the Smart Grid Standardisation ecosystem, EU funded researchers and innovators play an important role in the standardisation process. [ABSTRACT FROM AUTHOR]

The paper demonstrates a spectrum slicing technique applied to PAM-4 modulated signal spectrum at 40 Gbaud baudrate for optical access networks. The spectrum slicing is shown in VPIphotonics simulation environment, where characteristics of key components are measured in the laboratory and loaded into the corresponding elements of the simulation setup. The spectrum of electrical baseband signal is sliced in four slices introducing an additional degree of freedom – higher data rate signals can be transmitted by re-using already-existing lower bandwidth transceiver components in an optical access network. This tackles the electronic bottleneck enabling the on-demand variable bandwidth allocation and extends the life span of opto-electrical components during network upgrades. Furthermore, the use of the proposed spectrum slicing technique has a positive side-effect when it comes to security concerns, as the signal spectrum is divided into slices. All slices are necessary to obtain the reconstructed signal and even if an eavesdropper gets most of the slices it is still not enough. The simulation results show that the proposed spectrum slicing and stitching approach is a viable solution to overcome the problem of limited frequency bandwidth of electrical components. [ABSTRACT FROM AUTHOR]

The paper investigates the process of phase separation and morphology of organic-inorganic interpenetrating polymer networks (OI IPNs) based on the cross-linked polyurethane (PU), poly(hydroxyethyl methacrylate) (PHEMA) and poly(titanium oxide) (–TiO2–)n obtained by solgel method in the presence of poly(oxypropylene glycol) (POPG) at various molar ratio of titanium (IV) isopropoxide (Ti(OPri)4) and water. It has been established that the phase separation in OI IPNs depends on the kinetics of PHEMA-component formation and it occurs through the mechanism of the spinodal decomposition. It has been shown that by varying the ratio of IPNs components, content of inorganic component and Ti(OPri)4/H2O molar ratio it is possible to control the phase separation process and obtain OI IPNs with a different phase structure. [ABSTRACT FROM AUTHOR]

The study focuses on the development and evaluation of a motion control system for the Large Range Robotic Motion Simulator (LaRRMoS), which is based on a serial manipulator with 6 degrees-of-freedom. Two motion cueing algorithms (MCAs) – Classical Washout Filter (CWF) and Classical Washout Filter with Cylindrical coordinates (CYL) – are implemented and tested for simulation fidelity and LaRRMoS workspace utilization. CWF and CYL motion cueing performance gets assessed in two use cases: car simulation and luge sports simulation. The car case is a typical driving simulator application. The luge sports case is chosen for its high dynamics to assess the limits of the robot and motion cueing. Though this study uses a pre-recorded set of motion data and runs simulations in non-interactive mode, it aims for real-time interactive simulation for LaRRMoS in the future, so only MCAs capable of real-time operation are inspected. Conducted tests show that the CYL algorithm provides superior performance in highly dynamic motion replication, particularly in lateral accelerations. [ABSTRACT FROM AUTHOR]

Electromagnetic levitation (EML) is a promising technique allowing to melt various materials, including refractive metals, while avoiding physical contact between the molten material and components of the melting system, thus avoiding contamination of the molten material. EML coils act both as a container and a heating source for a conductive sample placed within it. EML systems are difficult to optimize for specific tasks and computational simulations are often used to aid the process. Development of simulations of EML processes is an ongoing field of research. Obtaining precise experimental measurement data of EML processes is important for development and verification of computational simulations. This study aims to provide experimental data of simultaneous measurements for magnetic field, Joule heating and lift force in different conical EML coils with a counterturn. [ABSTRACT FROM AUTHOR]

The hybrid photodetector (HPD) is a photomultiplier tube combined with the semiconductor device within the vacuum. The photoelectrons emitted from the photocathode directly hit the semiconductor enabling efficient electron multiplication with low noise and symmetric output pulse. These properties make a hybrid photodetector a good solution for photon-counting applications. At the Satellite Laser Ranging Station of the Institute of Astronomy at the University of Latvia, the hybrid photodetector characteristics were evaluated for SLR applications, including multiphoton mode and time-walk compensation. [ABSTRACT FROM AUTHOR]

The current study introduces porous ceramic materials fabricated from cenospheres through spark plasma sintering. The investigation delves into the impact of sintering temperature, mould diameter (20 and 30 mm), and cenosphere size on the resulting material properties. Notably, sample shrinkage initiates at 900 °C and demonstrates an upward trend with temperature escalation, while a larger mould diameter contributes to sample shrinkage. Elevated sintering temperature leads to increased apparent density across various sample series, such as CS 63–150 µm in a 20 mm mould (0.97 to 2.3 g/cm³ at 1050–1300 °C), CS 150–250 µm in a 20 mm mould (0.93 to 1.96 g/cm³ at 1050–1200 °C), and others in different mould sizes. Total porosity decreases from 61.5 % to 3.9 % with a rising sintering temperature (1050 to 1250 °C), while open porosity starts decreasing at lower temperatures. Closed porosity peaks in samples sintered at 1150 °C. Furthermore, an increase in sintering temperature from 1050 to 1300 °C boosts the compressive strength of CS 63–150 samples in a 20 mm mould from 11 MPa to 312 MPa. These findings align with the Rice model, illustrating an exponential relationship between compressive strength, material porosity, and fully dense material compressive strength. [ABSTRACT FROM AUTHOR]

Holograms recorded by focused light beams have several advantages over usual plane wave holograms such as reduced size, white light readout possibility and others. Focused polarization grating recording in an azobenzene-based molecular glasy film 5,5,5-triphenylpentyl 4-((4-(2-(4-bis(2-hydroxyethyl)amino)phenyl)-1-cyanovinyl)phenyl)dyazenyl)benzoate (which we shortly denoted as B11) is experimentally studied and compared with such grating recording in other materials. It has been determined that focusing manifests itself differently than in other materials, e.g., as in a-As2S3 and a-As-S-Se chalcogenide films. Thus, it reduces the holographic grating recording efficiency independently of recording and readout beam polarizations. It has also been found that recording efficiency with circularly and orthogonally L-R polarized beams is higher than with linearly polarized p-p beams. The highest diffraction eficiency of 26% is achieved with L-R polarized unfocused beams. Recording efficiency grating period dependences for unfocused beams at 200 J/cm2 exposure and at 1000 J/cm2 exposure are different with a maxima at 2 μm and 6 μm, respectively. In contrast, recording efficiency grating period dependences for focused beams at 200 J/cm2 exposure and at 1000 J/cm2 exposure are the same with the maximum at 6 μm. The obtained results are discussed in terms of trans-cis-trans photoisomerization followed by mass transfer and their light intensity dependence, light electric field gradient force, the photoinduced light scattering and photoelastic forces. [ABSTRACT FROM AUTHOR]

The accumulation of plutonium produced by LWR operations causes public concern related to its radiotoxicity and proliferation issue. Therefore, there is some interest in developing various methods for consuming plutonium through plutonium incineration i.e., by utilising thorium-based nuclear fuel. Thorium-plutonium mixed oxide fuel (Thorium MOX) is an attractive option considered for plutonium incineration. The aim of the study is to investigate the neutronic characteristics of Thorium MOX fuel in VVER-1000 nuclear reactor fuel assemblies. The VVER-1000 Benchmark model was utilised in the present study. A series of calculations were performed with the MCNP6 code and the ENDF/B-VII library. The calculation results show that a proper increase in Pu content could increase kinf of ThMOX fuel, so it could have almost the same kinf with MOX fuel or increase Pu content when needed. It was also shown that Thorium MOX fuel assembly had more negative Doppler reactivity due to neutron capture by thorium (232Th). The moderator temperature coefficient was found to be more negative than the Doppler coefficient, and it could be concluded that replacing uranium with thorium could reduce the amount of plutonium produced while increasing plutonium consumption. [ABSTRACT FROM AUTHOR]

In accordance with the goal approved by the Council of the European Union, a European climate-neutrality must be achieved by 2050. Namely, the European Union must significantly reduce greenhouse gas emissions and find ways to compensate for the remaining and unavoidable ones. Within the framework of the European Green Deal, which is a set of policy initiatives to achieve climate neutrality goals, energy communities are considered in the context of two initiatives: a just transition and clean and safe energy at an affordable price. Within the latter, energy community is seen as citizen-led actions in the energy sector that will help pave the way for the transition to clean energy. [ABSTRACT FROM AUTHOR]

The aim of the study is to analyse energy consumption for heating in set of the school buildings. Data analysis includes three data sets – predictions from energy performance certificates (EPC), measured data from heat meters and measured climate corrected data. Data sets were statistically checked and processed and represented graphically. The actual energy consumption differs from the one stated in the EPCs in all cases, which means that schools consume on average 15 % more energy than it is stated in the EPC. Overall, the data reveal that the actual energy consumption differs from the theoretical consumption, with all schools having higher actual consumption than the theoretical values. The differences in the data sets are discussed, and possible improvements are suggested taking into account strong relation between energy consumption and indoor air quality. [ABSTRACT FROM AUTHOR]

Quadrotor unmanned aerial vehicles (UAVs) are small, agile four-rotor systems suitable for various applications, from surveillance to disaster support missions. Hence, achieving high-precision trajectory tracking is crucial for their successful deployment. This research focuses on modelling, parameter identification, and Linear Quadratic Regulator (LQR) control design for quadrotors, aiming to enhance their trajectory following capabilities. The quadrotor dynamics are a sixth degree-of-freedom (6DOF) equation of motion derived from Newton's second law, encompassing moment of inertia, centre of gravity, weight, and thrust of propeller parameters. Experimental measurements are conducted to accurately determine these parameters, ensuring a realistic representation of the quadrotor system. Subsequently, a linearized model is constructed to provide a suitable plant for control system development. The LQR control design is intended to improve the trajectory tracking performance. This control strategy is validated through simulation and practical experiments, demonstrating its effectiveness in achieving high-precision trajectory following capabilites. The proposed approach demonstrates that LQR control effectively guides the quadrotor to resemble a predefined trajectory, experiencing only 3 % overshoot observed during the initial phase of flight. [ABSTRACT FROM AUTHOR]

Sustainability and longevity of existing gas grid exploitation perspective are closely related to two fundamental issues: their ability to adopt to changing gas fuel production and supply landscape in the context of methane-based fuels, mostly, biomethane, and in the context of non-methane-based fuels, mostly, low carbon and green hydrogen. Renewable gases and their ever-growing presence in gas transmission and distribution systems open up a discussion about the necessity to revise and restructure the original – vertically integrated layout of the gas systems, where gas supply is only technically possible from the transmission system towards distribution one, and not vice versa. Development of numerous decentralized biomethane production facilities connected to the gas distribution system causes a necessity to ensure the possibility to pass biomethane surplus of a certain production area into the gas transmission grid, thus avoiding necessity to install biomethane storage capacities locally and granting other regions an opportunity to use said surplus in their gas consumption immediately. The article addresses biomethane production trends and actions taken towards the development of reverse flow gas stations in France – one of biggest biomethane producers in Europe to date, and opportunities and challenges, which this technique might face in smaller and less active renewable gas markets as the one of Latvia. [ABSTRACT FROM AUTHOR]

During the pandemic and periods of martial law, educational institutions in Ukraine implemented various forms of organising the educational process, combining in-person and remote classes. As a result, there has been a decrease in the level of use of building premises. The analysis of the characteristics of energy consumption in these conditions requires additional attention. In this study, a dynamic energy model of the building was created using the educational building of Igor Sikorsky Kyiv Polytechnic Institute as an example. Energy consumption for heating needs was determined for normal operating conditions and quarantine conditions in Ukraine (only a specific part of the premises is being operated, ensuring that the standard temperature value is maintained while people are present). Based on the results of the study, the features of the energy consumption of the building during quarantine/martial law restrictions, subject to the partial use of the building, were analysed, and the main disadvantages of such a mode were identified. For the educational building of the university, the total energy consumption for heating needs depends on the number of rooms that are actively used, and the modes of regulation of heating and ventilation; the consumption can decrease depending on the chosen scenario by 61 %, 56 %, and 34 % in quarantine mode. The findings indicate that the efficiency of regulation modes can decrease by more than four times when compared to normal mode due to internal heat exchange with unoccupied rooms. [ABSTRACT FROM AUTHOR]

Persistent luminescence (PersL), also called long-lasting phosphorescence or simply afterglow, is a luminescence characterised by the emission of radiation from a few seconds to several days after the excitation source has been switched off. Over the past two decades, research on PersL materials, both in fundamental and applied physics, has developed rapidly; however, the explanation for the physical processes that cause afterglow still needs to be clarified. Today, PersL materials are used mainly for luminescent paints, safety signs and decorations. At the same time, research into using such materials in medicine, information storage, anti-counterfeiting technology, etc., is underway. Currently, information on the long persistent luminescence materials with emission in the blue and green spectral range is widely available. In contrast, the number of publications on the afterglow in the red and near-infrared spectral range is considerably lower. Within the framework of this research, Mg2SiO4: Mn2+; M3+ (M3+ = B3+; Al3+; Ga3+; In3+) materials were synthesised using solid state reaction synthesis. When excited with X-rays, the materials exhibited a broad Mn2+ PersL band with two maxima at approximately 625 nm and 730 nm. After cessation of irradiation, an afterglow of at least 6 hours could be observed. The research focuses on the trap properties of the materials. It was concluded that at least three discrete trap levels with activation energies approximately between 0.4–1.6 eV were present in the samples. Additionally, co-doping with Al3+; Ga3+; In3+ ions improved PersL longevity of the Mg2SiO4: Mn2+ material. [ABSTRACT FROM AUTHOR]

The present study assesses the heat characteristic of the nitrate-salt mixture as a phase change material (PCM) for a medium-temperature latent storage system (LSS). Two binary and ternary mixtures are evaluated, which demonstrate different thermal behaviour. The highest melting and latent heat capacity is obtained by KNO3(0.4)/NaNO3(0.6) at 223.8 °C and 161.5 J/g. However, it has a higher supercooling degree with a partial phase transition between 217.6 °C and 251.5 °C, making it unfeasible for a medium-temperature LSS tank. The ternary mixture (TM) with NaNO2(0.4)/KNO2(0.53)/NaNO3(0.7) demonstrates a stable phase transition with minimum partial phase transition (22.1 °C) and suitable heat of fusion (98.1 J/g). Further evaluation through static thermal profiling demonstrates that the TM has a notable performance during solid-sensible charge with a charge level indicator (CLI) around 45.3 %–49.1 %. The TM can be charged up to 85.7 % until the end stage of the phase transition. It promotes a better storage capacity with suitable performance since the system can be charged effectively at a suitable temperature range (< 160 °C) for various applications. The micrograph observation indicates some dispersed particles and local agglomeration, which makes phase stabilization as an advantageous method to promote a stable phase change process. The TM can be considered a suitable PCM for a medium-temperature LSS tank that allows for a better solar thermal renewable system operation. [ABSTRACT FROM AUTHOR]

A method of accuracy error compensation for the time interval is examined, allowing to decrease the dependence of accuracy error on the duration of measured intervals and minimising the influence of destabilising factors – ambient temperature changes and the initial deviation of the meter clock generator frequency from the nominal value. The compensation method is based on a calibration procedure that measures precise time intervals under conditions of changing ambient temperature. Then the dependence of the accuracy error on temperature for a particular meter is recorded. Based on these data, a correction table is compiled containing correction factors and temperature values at which these factors were determined. Under real measurement conditions, the correction factor corresponding to the current temperature is determined from the table for measured result correction. The table with correction factor values could be stored in the memory of the meter or processing computer. Experimental verification of the method showed that applying a correction for a meter with a standard XO class clock generator (certificated instability of ±50 ppm) could obtain an equivalent clock generator instability of ±0.15 ppm. The application of the method is efficient in cases where the use of high-end clocking to ensure the required measurement accuracy is not economically feasible. [ABSTRACT FROM AUTHOR]

The study explores the detection of a harmful, wide-band interference signal, whose origin is a traditional desk LED (light-emitting diode) lamp. The interference signal was noticed on the sensitive solar spectrometer observing system, which was operating at a frequency range between 100 and 300 MHz. The interference signal was so strong and wide-band that it destroyed totally the solar observations. The study introduces two practical EMI (Electromagnetic Interference) reducing methods: ferrite cores and shielding (shielding effectiveness, S.E.). Their theoretical background is presented, and, in addition, these methods are tested in practice. The measurements and tests showed that even simple ferrite core was a very effective method to reduce interference effects. It is important that a suitable setup will be found: a single ferrite core cannot solve a whole problem. This interference problem is very demonstrative and it can be used in educational purposes at an undergraduate level at Metropolia University of Applied Sciences, Finland. This study reveals the fact that standard lamps, which are on the market, do not necessarily follow good EMC (Electromagnetic Compatibility) practices. [ABSTRACT FROM AUTHOR]

Silver nanoparticles (NPs) have gathered extensive attention due to their properties – chemical stability, good conductivity, catalytic activity, and antimicrobial activity. This makes NPs suitable for potential applications in the development of new technologies in the field of photonics, electronics, medicine, biochemical sensing, and imaging. Nanoprisms have local surface plasmon resonance starting from visible to near infra-red spectrum, broadening the possibilities of their applications. Ag NPs typically are synthesized in aqueous solution but the handling of NPs often requires their dispersion into nonpolar solvents and their mixing with organic compounds. Thus, nanoparticle transfer to organic media is essential for application in the field of emission enhancement due to NPs – organic semiconductor interaction. A shell changing method for NP tranfer was successfully used with a high transfer rate, but rather low stability. The previously proposed sonochemical method for NP transfer from aqueous to organic polymeric media is extended to different organic solvents. The ultrasonic method is suitable to obtain stable NPs in both organic solvent and organic solvent/organic compound solutions, and it can be stored at ambient conditions for at least several months. Transfer efficiency is suficient and NPs remain stable in an organic solvent like chlorobenzene, anisole, dichloromethane. The method has potential in NPs containing thin film preparation because sonication prevents the agglomeration of clusters. [ABSTRACT FROM AUTHOR]

The exposure buildup factors in concrete and lead for a point isotropic and flat unidirectional photon source in the energy range from 10 to 50 MeV were determined using Monte Carlo simulation "FLUKA" software. The exposure buildup factors were also obtained for different material thickness up to 40 mpf. The calculations were done in a barrier geometry where the contributions of all photon-matter interactions were taken into account in the performed calculations. Amendments for the barrier-geometry effect for both materials under study were deduced. The results showed that barrier-effect amendments were independent of the material thickness, material type, and energy of the photon source [ABSTRACT FROM AUTHOR]