In this paper, we present an internally developed sensing system featuring an integrated 6 degrees-of-freedom (6 DoF) accelerometer designed to provide a rapid and remarkably simple solution for measuring low frequency vibrations — such as flow-induced vibrations — or other movements of solid structures in educational, research, and industrial applications. Given its highly compact form factor, the device supports wireless communication and onboard data logging to a memory card. Since neither power supply nor data transmission requires a wired connection, it is also suitable for analyzing the motion of untethered, freely moving bodies. According to its modular architecture, the sensor can be fitted with custom housings tailored to diverse geometric constraints and produced rapidly using SLA 3D printing technology. In addition to outlining the design considerations, we detail the device's construction and capabilities, then validate its performance by comparing measurement results from a simple autonomous chaotic mechanical system experiment with a vision-based measurement method.
Geothermal energy represents a reliable and low-carbon resource with significant potential for both heat and electricity generation, particularly in regions characterized by medium-temperature reservoirs such as the Pannonian Basin. However, the efficient utilization of these resources requires an integrated approach that simultaneously considers subsurface geological conditions and surface-level constraints. This study presents a comprehensive methodology for the first-order evaluation of geothermal resources for combined heat and power production. The approach integrates geological risk assessment, based on Common Risk Segment (CRS) and Composite Common Risk Segment (CCRS) mapping, with a GIS-based multi-criteria analysis of environmental, technical, and socio-economic factors. The methodology is applied to a case study in southwestern Hungary (B & oacute;ly region), where potential locations for new geothermal doublets are identified and evaluated. Preliminary reservoir simulations indicate that the selected doublets can provide up to 4.2 MWth thermal capacity over several decades. The integration of geothermal heat into district heating systems, combined with electricity generation using Organic Rankine Cycle (ORC) technology, enables efficient cascading utilization of the resource. Under representative conditions, the system can supply a substantial share of local heat demand while producing several GWh of electricity annually. Another case study of an existing well near Szarvas (southeastern Hungary) was also presented. The results demonstrate that medium-temperature geothermal resources can support decentralized energy systems and contribute to improved energy security, resource efficiency, and decarbonization.
In sheet metal forming processes such as deep drawing, planar anisotropy plays a crucial role in determining the final geometry. The formability of sheet metals depends on their anisotropic behavior; therefore, anisotropy can be a limitation of forming. Accurate finite element modeling of sheet metal forming processes requires a robust description of anisotropic behavior. The standardized approach for determining anisotropy is tensile testing at different angles relative to the sheet metal's rolling direction. Biaxial behavior is also important for the yield function of the materials. Although several methods are available for determining biaxial properties, the disk compression test is relatively simple and easy to perform and, therefore, a favorable method in an industrial environment. The goal of the present study is to determine the biaxial anisotropy coefficient of LDX2205 duplex stainless steel (DSS). Although the proper lubrication and the appropriate test methodology are unknown, a comparison is needed to define the methods and lubricants for further investigations. The tests were conducted with three lubricants to identify the most reliable one: a high-contact-pressure grease, a graphite-containing grease, and PTFE sheets. Based on measurements, the greatest deformation occurred when PTFE sheets were applied; therefore, further tests were performed using these sheets. Three series of compression tests were performed: a fully compressed series, a gradually compressed series, and a load-driven series. The investigations were carried out to examine the influence of the different methods on the parameter. Microhardness tests were conducted on the as-delivery-conditioned material and on the compressed material.
The impact of vibration phenomena on gas turbine operation and production quality can significantly reduce their service life. Balancing the rotating elements of these machines is a valuable method for reducing production losses and avoiding the need for total machine dismantling. In this study, a gas turbine type MS3002 with two rotors was examined on-site to minimize the phenomenon of unbalance and provide correction angles at the rotor level. This balancing process enabled the control and improvement of the mass distribution of the rotor to maintain efforts and vibrations caused by unbalance within acceptable limits while ensuring the optimal operation of the turbine. The results demonstrate the importance of balancing techniques in extending the service life of gas turbines and maintaining optimal performance.
The tribological behavior of metal-polymer friction pairs depends to a large extent on their surface roughness. In this study, we analyze the friction of C45 (1.0503) steel and polypropylene homopolymer (PPH) in terms of the surface roughness characteristics of the material pair subjected to friction. The results of the friction experiments described in the article showed that during the friction process, the investigated roughness parameters of the steel specimen (Ra-average surface roughness, Rz-roughness height or tenpoint height, Rp-maximum peak height, Rv-maximum valley depth) remained essentially unchanged, while the same roughness parameters of the polymer surface significantly changed and adapted to the roughness characteristics of the steel. Ellipsometric measurements also confirmed the presence of a 20-30 nm thick polymer transition film on the steel surface, and there were parts of steel on the polymer surface as well. The obtained results indicate that in the case of metal-polymer friction pairs, the change in surface roughness is asymmetric (the surface roughness of the harder material shapes the softer surface). In contrast, material transfer is bidirectional. These must be taken into account in friction modeling and wear prediction.
