International Scientific Journals
of Scientific Technical Union of Mechanical Engineering "Industry 4.0"

This paper talks about how we can use math to create better models based on actual compressor experiments. The goal? To bridge the gap between what we see happening in real life and what we can predict, ultimately helping us optimize HVAC systems for better performance.
Within these systems, parts like compressors, fans, and electrical components play crucial roles. Compressors, especially, are quite dynamic, especially in heat pump setups.
However, the problem is that manufacturers usually only give real-world data on how compressors perform, without detailed models for understanding how they work in different situations. Hopefully in this paper we will try to construct a detailed model in order to be able to evaluate a HVAC system without the necessity of real-world data. Also, we will evaluate two different mathematical models, two dimensional interpolation and approximation in order to see who perform better.

The main sources of green energy (GE), considered as the cleanest forms of energy or types of renewable energy sources (RES), are wind, water, sun, and earth. While the world, particularly in the most developed countries, has made significant progress in adopting and applying the various forms of green energy (GE), in Georgia this field is in its initial stage and it is not possible to predict when the first major positive developments will be made. This paper presents an analysis of total energy supply (TES) in Georgia for the period 2000-2021. The value of the continuous annual growth rate (CAGR) for TES in Georgia for this period is 7.23.

Obtained experimental self-cleaning coatings (based on compositions with the participation of Eu2O3), applied by the sol-gel method on glass slides. The luminescence of the obtained thin layers of different ratios of the compositions were investigated. A strong emission from the 5D0 level of Eu3+ ions was registered under near UV (392 nm) excitation using the 7F0 → 5L6 transition. The values of the integrated fluorescence intensity ratio R (5D0→7F2)/(5D0→7F1) was calculated to give information about the degree of asymmetry in the vicinity around the active ions, suggesting a location of Eu3+ in non-centrosymmetric sites. The highest Eu3+ luminescence is observed in sample with 3 layers coating. The experimental results represent a prerequisite for the development of a series of additional compositions and a detailed technological regime for obtaining various modifications of resistant, long-lasting self-cleaning coatings, potentially applicable to photovoltaic panels.

In recent years, natural disasters have frequently occurred in Japan, almost yearly, causing enormous damage. In Hiroshima Prefecture, heavy rains in August 2014 and July 2018 caused large-scale landslides. Power outages continued in the affected areas, and some survivors had been lighting campfires outdoors and using candles indoors. In times of disaster in which bad weather persists, it is difficult to safely secure lighting, which can adversely affect health. Lanterns can be created by putting a few drops of milk into a PET bottle filled with water and shining light from the bottle’s bottom. In this study, we used a light emitting diode (LED) as a light source to evaluate the luminance of handmade lanterns. Results suggested that when using tap water with one LED lamp and a 500 ml PET bottle, 1–2 drops of milk are suitable to achieve the optimal light scattering effect.

This paper examines an innovative approach for modeling the influence of climate parameters on transport infrastructure using artificial neural networks. Through them, detailed climatic data are generated by geographical positions and monthly and annual maps are created for Bulgaria’s territory using the following parameters: surface temperature, diffuse fraction, horizontal solar irradiation, and average albedo of the terrain. Average ground temperature and monthly solar irradiation are essential for maintenance planning and developing strategies to adapt to extreme weather conditions, such as heat waves or frost, which can affect the condition and performance of the road surface. Average monthly temperatures can be used to design effective systems to prevent icing of road surfaces and improve drainage systems. By demonstrating the capabilities of accurate modeling and analysis, this paper highlights the importance of applying artificial neural networks in planning and improving the resilience of transport infrastructure against climate change.

In this paper, the tensile strength of the composite material made of onyx and carbon fibers was investigated. Onyx is a material manufactured by the company Mark Forged, which is used for 3D printing of composite materials. It is a thermoplastic filled with carbon fibers used for printing solid and rigid parts. The tensile test according to the standard ISO 527 was carried out experimentally and the numerical results were obtained by numerically modelling the test specimen and simulating the test in Ansys, after which the results obtained experimentally and numerically were compared.

For various canonical forms (plane, cylinder, ball, etc.), a generalized mathematical model (MM) of a nonlinear steady-state process of molecular heat transfer (or moisture diffusion) through enclosing structures (ES) is proposed, taking into account infiltration or exfiltration of a vapor-air (gas) mixture and the presence of various internal or surface positive (moisture condensation) or negative (evaporation of moisture) of heat sources (HS). The mathematical formalization of the posed boundary value problem (BVP) of transfer and its general solution are given, on the basis of which, under various specified conditions of unambiguity, solutions of specific physical processes with constant or variable thermophysical characteristics and HS are constructed and analyzed. For large-scale transitions, the short-circuit problem is posed and solved under various boundary conditions (BVC), written in a criterion form as dependences of the dimensionless temperature T(R-, Pe, Po) on the dimensionless thermal resistance (R-) of the heat exchange criteria for the similarity of Pecle (Pe) and Pomerantsev (Po).

Current construction practice often implies the need to carry out specific actions related to the specification of current operating characteristics of existing and operated in different periods in different ways fibre-reinforced industrial concrete internal floorings and external pavements. Such problems are most often related to a planned change in the operating load, or to estimate their service life in the future. In this regard, specific parameters of a system approach proposed by the author are specified below, including the necessary preliminary field, laboratory and analytical activities related to establishing the current strength-deformation and other essential characteristics of existing industrial concrete floorings and pavements, as follows: concrete cross-section thickness, concrete strengthdeformation characteristics, type and amount of reinforcement used (including fibres), deformation characteristics of the crushed-stone base – according to the dynamic penetration in number of test points, static calculations for the new load conditions, restoring their integrity after sampling, etc. Given the lack of any normative documents on the subject, the proposed systematic approach to the assessment of the residual operational resource of existing fibre-reinforced industrial concrete floorings/pavements is of important methodological importance and fully corresponds to the needs of real construction practice. Its practical use has been approved by the author through a number of successfully conducted systematic expert procedures at a number of sites in the country and abroad.

The paper discusses the possibilities of joining thin-walled metals and composites reinforced with bidirectional carbon/glass fibres. The experimental part of the paper contains metallographic sections and results of load-bearing capacity testing of pilot metalcomposite joints with thermoplastic matrix and glass and carbon fiber reinforcement, formed by thermal drilling technology. As a result, a sequential joining method is proposed which can achieve the optimum joint geometry with a hem to keep the joint from opening under tensile stress.

Vanadium, a vital element for the advancement of clean energy technologies, holds the potential to revolutionize the energy landscape. This study investigates the distribution of vanadium within Jordan huge rock phosphate deposits, exploring its implications for sustainable energy transitions. Utilizing advanced analytical techniques, including X-ray fluorescence spectroscopy and scanning electron microscopy, were scrutinized the intricate geochemical characteristics of these deposits. The concentrations of Vanadium in different samples of Jordanian rock phosphate, encompassing Al-bied, Al-Hasa, and Eshidiya (A1, A2, A3, S1, and S2), as well as phosphoric acid, were analyzed. The Vanadium concentrations observed were 181 mgkg−1, 204 mgkg−1, 107 mgkg−1, 117 mgkg−1, 55 mgkg−1, 237 mgkg−1, and 291 mgkg−1, and 135 mgkg−1, respectively. The findings unveil promising concentrations of vanadium within Jordanian rock phosphate, positioning the country as a potential key player in the global supply chain of this critical metal. By elucidating the abundance and distribution of vanadium in Jordan rock phosphate, this research not only contributes to the understanding of vanadium fate and distribution but also underscores the imperative of sustainable resource utilization in advancing towards a cleaner and more resilient energy future.

This paper presents an exergy analysis of a two-cylinder low power steam turbine from combined cycle power plant at three operating regimes. The highest mechanical power produced in the whole turbine is 6807.24 kW in Operating regime 1. Cylinders of the observed turbine did not have the same operation dynamics in relation to produced mechanical power in all operating regimes. In each operating regime High Pressure Cylinder (HPC) has lower exergy destruction and higher exergy efficiency in comparison to Low Pressure Cylinder (LPC) due to the influence of wet steam which expands through the last LPC stages (water droplets in wet steam increases LPC exergy destruction and decreases LPC exergy efficiency). Whole turbine exergy efficiency is between 51.62% (in Operating regime 2) and 64.98% (in Operating regime 1). This range of exergy efficiencies can be expected for a low power steam turbine. An increase in the ambient temperature decreases exergy efficiency of the whole turbine and both turbine cylinders, regardless of the observed operating regime. The exergy efficiency of the LPC is low in all operating regimes, so any improvements should be based on this cylinder first.

The contribution is focused on the analysis of the surface roughness after applying the conversion layer using phosphating. In the experiment, uncoated deep-drawn steel DC 04 was used as the base material. During the application of the conversion layer, changes in surface roughness were studied with respect to the phosphating time, which was 3, 5 and 10 minutes. The achieved results provide information for other technological operations such as creating joints by gluing, where the correct anchoring of the glue is important for sufficient adhesion to the surface.