Browsing by Issue Date, starting with "2026"

Now showing 1 - 20 of 104

Access status: Open Access ,
Systems of differential inclusions with competing operators and variable exponents
(Wydawnictwa AGH, 2026) Vetro, Francesca; Efendiev, Rakib
In this paper, we study a system of differential inclusions with Dirichlet boundary condition, involving competing operators and variable exponents. More precisely, we investigate the existence of both generalized solutions and weak solutions to the problem under consideration. In order to archive our results, we make use of approximation through finite dimensional subspaces via a Galerkin basis along with minimization and nonsmooth analysis.
Access status: Open Access ,
Anisotropic singular logistic equations
(Wydawnictwa AGH, 2026) Da Silva, João Pablo Pinheiro; Failla, Giuseppe; Gasiński, Leszek; Papageorgiou, Nikolaos S.
We consider a parametric Dirichlet problem driven by the anisotropic $(p,q)$-Laplacian and a reaction with a singular term and a superdiffusive logistic perturbation. We prove an existence and nonexistence theorem which is global with respect to the parameter $\lambda\gt 0$.We consider a parametric Dirichlet problem driven by the anisotropic $(p,q)$-Laplacian and a reaction with a singular term and a superdiffusive logistic perturbation. We prove an existence and nonexistence theorem which is global with respect to the parameter $\lambda\gt 0$.
Access status: Open Access ,
High-Volume Return Premium on the Warsaw Stock Exchange: evidence, drivers, and strategy design
(Wydawnictwa AGH, 2026) Sieradzan, Olga; Wójtowicz, Tomasz
This paper investigates the High-Volume Return Premium (HVRP) on the Warsaw Stock Exchange from 2002 to 2023. Building on prior research, it tests whether an unusually high trading volume predicts short-term return anomalies. Using daily data and long-only strategies based on relative trading volume, the study confirms the existence of the HVRP, with the strongest effects observed over one-day horizons, particularly for mid-cap and low-priced stocks. The premium weakens with longer holding periods and lower trading activity. These findings indicate that trading volume carries predictive information in an emerging market context and that volume-based signals can generate exploitable short-term return patterns. However, practical constraints such as transaction costs may limit the real-world profitability of such strategies.
Access status: Open Access ,
Monitoring stateczności wyrobisk górniczych i tunelowych
(Wydawnictwa AGH, 2026) Małkowski, Piotr; Niedbalski, Zbigniew; Bednarek, Łukasz
Wydział Inżynierii Lądowej i Gospodarki Zasobami
Access status: Open Access ,
Study of the effectiveness of restoring the permeability of near-borehole zones
(Wydawnictwa AGH, 2026) Bystrai, Artur
When drilling into a reservoir zone, the main goal is to reach the reservoir without damaging the pore space. Damage to the pores can happen because of the drilling mud. Drilling mud, especially when it has solid particles and clay, can block the pores near the wellbore, which is called formation damage. To avoid this, drilling fluids often contain bridging agents, usually finely ground carbonate rocks. These small particles move into the pore spaces of the reservoir zone. While drilling through the productive layer, they protect it from the further invasion of drilling mud and its filtrate. After the drilling is finished, the area where the bridging agents entered the formation is cleaned with hydrochloric acid ($HCl$). The acid reacts with the carbonate ($CaCO_{3}$), dissolving the blocking material. This process restores the permeability of the reservoir zone and allows hydrocarbons to flow freely into the well. The aim of this work is to explain the theoretical background of this topic and to perform laboratory tests that confirm the effectiveness of this process.
Access status: Open Access ,
Artificial intelligence-enhanced algebraic multigrid for 3D finite element simulations
(Wydawnictwa AGH, 2026) Goik, Damian; Banaś, Krzysztof
The paper presents preliminary investigations into a strategy for solving linear systems resulting from 3D finite element simulations, based on the algebraic multigrid (AMG) method, enhanced using artificial intelligence techniques. In particular, we adapt to 3D problems the algorithm presented in Luz et al. (2020) for using a graph neural network to create the prolongation and restriction operators in a way that will improve convergence. The process of training the network proceeds on the basis of a set of system matrices obtainedfor tasks much smaller in scale than the target problem to be solved. Learning is aimed at decreasing the spectral radius of the error propagation matrix after applying modified prolongation and restriction. We describe some implementation details of the solver developed based on the presented strategy and show several numerical examples of its application for medium-sized problems.
Access status: Open Access ,
Geometric optimization of two-stage stamping dies for ultra-thin titanium bipolar plates using Sequential Physics-Informed Neural Networks
(Wydawnictwa AGH, 2026) Ke, Zijie; Huang, Yiwen; Guo, Ziqiang; Xiao, Yao; Hou, Zeran; Min, Junying
Bipolar plates are critical core components in proton exchange membrane fuel cells (PEMFCs). Titanium-based materials are highly favored due to their excellent corrosion resistance and high specific strength. However, the plates often experience severe local thinning and poor consistency in forming dimensions during the two-stage stamping process. Although traditional finite element method (FEM) optimization can mitigate these defects, it comes with high computational costs and time consumption. This study proposes a die design optimization framework based on the Sequential Physics-Informed Neural Network (S-PINN). Unlike traditional single-layer neural network models, S-PINN adopts a sequential architecture that effectively maps the two-stage forming process of the plates. This architecture can explicitly predict the evolution of forming quality from the pre-forming stage to the final stage. By embedding the core physical laws of plastic deformation into the network loss function, the S-PINN model effectively predicts the complex nonlinear relationship between mold geometry and forming quality, while ensuring physical consistency. Experimental and simulation results show that the S-PINN model’s prediction accuracy for dimensional consistency (DC) is 73.8% higher than that of the PINN model and 33.9% higher than that of the S-ANN model. Compared with traditional modeling methods, the S-PINN-optimized die design can reduce the thinning rate and improve channel dimensional consistency.
Access status: Open Access ,
A Digital Twin for temperature prediction in the laser hardening process of NC10 steel
(Wydawnictwa AGH, 2026) Lacki, Piotr; Derlatka, Anna; Lacki, Michał; Lachs, Kuba
In this study, Artificial Neural Networks (ANN) were created to develop a Digital Twin (DT) for temperature prediction in the laser hardening process of NC10 steel. The ANN were trained to predict temperature on the top layer during the laser hardening process of NC10 steel samples with different thicknesses and with various laser power and laser scanning speeds. The prediction developed during the project work was based on a parametric numerical model of the laser hardening process for a sample of NC10 steel, using the Finite Element Method (FEM) within the ADINA software. Numerical simulations enabled a detailed analysis of the temperature produced on the surface of each sample, as well as a visualization of the structural changes made to the sample according to the laser hardening process. It is crucial to create data that reflects reality as closely as possible to assess the best setting for each process. A well created DT allows to make automatically important changes along laser hardening process. To obtain a set of the most efficient parameters for the desired result, Genetic Algorithms (GA) were integrated with the developed ANN. As a result, the authors developed an effective and efficient tool to predict the temperature produced along the laser hardening process.
Access status: Open Access ,
Integration of MASW and ERT methods for site characterisation: a case study from Czernichów (Southern Poland)
(Wydawnictwa AGH, 2026) Cichostępski, Kamil; Bania, Grzegorz; Borecka, Aleksandra
The paper presents an integrated use of multichannel analysis of surface waves (MASW) and electrical resistivity tomography (ERT) to characterise the physical properties of near-surface materials, identify subsurface structures, and estimate the depth to bedrock in a planned construction area near Czernichów, close to Krakow (southern Poland). The study shows that integrating MASW and ERT provides a cost-effective and complementary approach to subsurface characterisation, delivering more reliable and less ambiguous interpretations than when the methods are applied independently, thereby reducing the need for expensive and invasive in situ geotechnical investigations. Particular emphasis is also placed on the methodological aspects of both methods. The study site is located on an alluvial plain composed of alluvial soils, sands, sand–gravel mixtures, and silty clays overlying limestone bedrock. Geophysical data were collected along five profiles. The resulting shear wave velocity models and the inverse model resistivity sections show good agreement with borehole data. The study area is characterised by a wide range of physical parameters derived from both methods. The MASW survey enabled recognition of the subsurface down to the bedrock, revealing four seismic layers differing in S-wave velocity. Nevertheless, the MASW inversion did not provide reliable estimates of the limestone S-wave velocity, although it successfully delineated its depth and morphology. The ERT survey identified three geoelectrical layers and proved to be more effective in resolving shallow geological structure, particularly in identifying the boundaries between alluvial soils and sand–gravel mixtures, whereas the depth and morphology of the limestone bedrock were constrained primarily by MASW.
Access status: Open Access ,
Application of the ground penetrating radar (GPR) method in the detection of underground utilities above the Kobilja Glava Tunnel
(Wydawnictwa AGH, 2026) Bektašević, Ekrem; Filipović, Satko; Bojić, Mirnes; Crnogorac, Luka; Gutić, Kemal; Skrzypkowski, Krzysztof
Accurate detection and mapping of underground utilities in complex urban environments, particularly in intensive construction zones such as tunnel sites, presents a significant engineering challenge. This paper investigates the application of ground penetrating radar (GPR) integrated with high-accuracy real-time kinematic (RTK) GNSS positioning to identify and spatially define a damaged sewer pipeline above the Kobilja Glava tunnel construction site in Sarajevo, Bosnia and Herzegovina. Non-destructive investigation was required due to the lack of reliable underground utility documentation and wastewater ingress into the tunnel during construction. The study was conducted under complex urban and geotechnical conditions, including asphalt pavement, high soil moisture, heterogeneous subsurface layers, and proximity to the tunnel. GPR surveys were performed using a dual- channel Leica DS2000 system with 250 MHz and 700 MHz antennas, combining grid-based and free-profile measurements. Spatial georeferencing was achieved with a Topcon Hiper HR RTK GNSS receiver, which provides centimeter-level positioning of identified reflectors within the national coordinate system of Bosnia and Herzegovina. Data processing and interpretation followed standard GPR procedures. Results show that the sewer pipeline was reliably identified through hyperbolic reflections, with the depth of the pipe crown ranging from 1.1 to 1.7 m. Integration of GPR and GNSS data enabled precise reconstruction of the pipeline’s position and depth, supporting the design of a new pipeline and reducing construction risks. The study demonstrates the high effectiveness of the integrated GPR-GNSS approach in complex urban environments near tunnel structures. These findings suggest that the integration of GPR and GNSS technologies serves not only for object detection but also provides a critical methodological framework for real-time risk assessment during underground construction. The study demonstrates how precise spatial definition of damaged infrastructure can prevent broader geotechnical instabilities, elevating the work from a local case study to a universal model for monitoring urban infrastructure under stress.
Access status: Open Access ,
Electrical imaging and 3D modeling of a discontinuous aquifer: Insights from Toumbakro, Bouaké, Côte d’Ivoire
(Wydawnictwa AGH, 2026) Loukou, Kouamé Gbèlè Hermann; Kouamé, Loukou Nicolas; Kouadio, Kouao Laurent
A geophysical survey using electrical imaging in the Wenner–Schlumberger configuration was carried out in a crystalline basement region in central Côte d’Ivoire to improve knowledge of the aquifers in this area affected by recurrent water stress. The 2D resistivity sections, corroborated by petrographic field observations and drilling data, led to the development a 3D conceptual model of the aquifers in the study area. This model distinguishes three main lithological units: a resistant surface cover consisting of a lateritic cuirass, a conductive alteritic layer, and, at the base, a more or less fractured crystalline basement. From a structural point of view, several fracture networks have been identified, with predominantly NW–SE, NNW–SSE, and N–S orientations, constituting potential groundwater circulation zones.
Access status: Open Access ,
The effect of different additives on the immobilization of heavy metals, the stability of organic matter, and the ecotoxicity of municipal sewage sludge
(Wydawnictwa AGH, 2026) Gondek, Krzysztof; Baran, Agnieszka; Siudek, Michał
There is an ongoing search for the most environmentally friendly use of various materials as additives to improve sludge properties. The aim of this study was to analyze the effect of additive type and dose of biochar (BC), dolomite (DL), bentonite (BN) or diatomite (DT) on heavy metal immobilization, organic matter stability, biochemical activity and ecotoxicity of municipal sewage sludge (SS). Risk Assessment Code (RAC) and Ecological Risk Factor (ERF) values indicated low risk associated with heavy metal (HM) mobility. Higher non-hydrolyzing C contents, compared to SS control, were found in SS to which 1% BC (by 3.6%), 1% DL (by 38.0%), 1% BN (by 25.5%) and 1% DT (by 20.6%) were added. Higher ratio C humic acids/C fulvic acids (Ckh/Ckf) values (more than 30% on average) were obtained when 1% BC, DL or BN were added compared to the 3% addition. Compared to the SS, the Ckh/Ckf values in SS with the addition of BC, DL or BN were on average more than 19% higher. The least varied values of dehydrogenase activity and respiration activity of SS (within dose) were obtained after the application of DT and BC, while the values of both parameters differed the most when BN was added to SS. Based on the results, it is not possible to clearly state which of the applied additives had the most significant effect on reducing the biochemical activity of SS. Sewage sludge and its mixtures generally showed low phytotoxicity to Sorghum saccharatum and Lepidium sativum, as root growth inhibition was 8–56% and 17–48%, respectively.
Access status: Open Access ,
The use of oxytrees in the purification of the soil and water environment in the area of municipal waste landfills
(Wydawnictwa AGH, 2026) Dąbrowska, Dominika; Rykała, Wojciech; Nadgórska-Socha, Aleksandra; Kandziora-Ciupa, Marta; Wdowczyk, Aleksandra
Municipal waste landfills are an important source of soil and water pollution due to the generation of leachates rich in heavy metals, salts, and organic pollutants such as polycyclic aromatic hydrocarbons (PAHs). Conventional remediation methods are expensive, sparking interest in phytoremediation as a sustainable alternative. This study evaluates the potential of Paulownia tomentosa (oxytree) in remediating soils contaminated by landfills. Seedlings were grown under controlled conditions and irrigated with distilled water, 50% landfill leachate, and 100% landfill leachate. Chemical analysis of the soil, roots, stems and leaves revealed the selective accumulation of macronutrients (particularly nitrogen and phosphorus) and selected potentially toxic elements (such as lead, zinc and copper), with the contaminants primarily retained in the roots. Stress biomarkers indicated significant physiological responses, including increased proline levels and decreased phenol and flavonoid content, reflecting plant stress under elevated leachate exposure. Notably, P. tomentosa demonstrated the ability to reduce 4- and 5-ring PAH concentrations, particularly at moderate leachate levels. However, its overall remediation effectiveness was limited in comparison to phytoremediation grasses, which exhibit stronger contaminant removal potential. These results indicate the limited suitability of Paulownia for landfill remediation, emphasizing the need to optimize leachate concentrations.
Access status: Open Access ,
Application of seismic refraction methods for rock mass characterization at the lead mine tailings site in Olovo Mine
(Wydawnictwa AGH, 2026) Bektašević, Ekrem; Skrzypkowski, Krzysztof; Kahrimanović, Semir; Crnogorac, Luka; Gutić, Kemal
In this study, the application of seismic refraction for the characterization of the rock mass at the lead mine tailings facility in Olovo is presented, with the aim of identifying lithostratigraphic horizons, structural discontinuities, and zones of reduced mechanical resistance that may affect tailings stability. The investigations were conducted along seven seismic profiles of varying lengths and resolutions, designed to cover both shallow and deeper portions of the rock mass to a depth of approximately 60 m. Data processing and interpretation were carried out using the Delta-t-V seismic tomography method, which enables reliable reconstruction of P-wave velocities even under conditions of complex geological structure and velocity inversions. The obtained results indicate pronounced heterogeneity of the rock mass, with clearly differentiated zones of surface embankments and unconsolidated materials (600–1,200 m/s), transitional zones of degraded and karstified rocks (1,800–3,200 m/s), and basal horizons of compact limestone, where P-wave velocities reach values of approximately 4,400 m/s. Particular attention was given to locally developed low-velocity anomalies within deeper horizons, interpreted as karst structures and cavernous zones that are potentially critical for tailings stability. By integrating the individual profiles, a unified 3D rock mass model was developed, enabling spatial analysis of anomalies and reliable terrain zoning. The results confirm that seismic refraction, combined with the Delta-t-V method, represents an efficient, non-destructive, and engineering-relevant tool for characterizing complex tailings rock masses. The developed models have direct application in stability assessment, remediation planning, and the enhancement of mining and environmental safety systems.
Access status: Open Access ,
Zgrzewanie tarciowe z mieszaniem materiału (FSW) wysokowytrzymałych stopów aluminium obrabialnych cieplnie ze stopami nieobrabialnymi cieplnie
(Wydawnictwa AGH, 2026) Kalemba-Rec, Izabela
Wydział Inżynierii Metali i Informatyki Przemysłowej
Access status: Open Access ,
The Influence of Modified Inorganic Binders Intended for 3D Printing on Selected Properties of Thermally Cured Moulding Sands – Conventionally and with Microwaves
(AGH University Press, 2026) Halejcio, Dawid M.; Major-Gabryś, Katarzyna
This study determined the impact of thermal curing on the basic properties of moulding compounds made with commercial inorganic binders and binders based on them, modified for use in 3D printing technology (Binder Jetting). Two inorganic binders based on sodium silicate and a binder based on aluminosilicates were tested. As part of the work, the parameters for thermal curing of the mixtures were selected: for curing in a dryer, the best properties were obtained for mixtures containing 2.0 p.p.w. of binder cured for 10 min at 160°C. In the case of microwave curing, the best properties were obtained for moulding sands containing 2.0 p.p.w. of binder cured for 6 min at a device power of 800 W. The tests showed that the basic properties of moulding compounds with binders developed on the basis of commercial binders for use in 3D printing technology, thermally cured in a dryer, do not differ significantly from the properties of compounds with commercial binders. In the case of microwave curing, a reduction in the strength of compounds with new binders was observed in relation to compounds with classic binders. Thermal deformation tests of compounds with classic and modified binders confirmed the typical behavior observed for inorganic systems. It was proven that new, modified inorganic binders developed for 3D printing of moulds and cores using Binder Jetting technology can be used as binding materials in thermally cured moulding sands. Both thermal curing methods were assessed as suitable for curing moulding compounds with new binders.
Access status: Open Access ,
Microstructure-erosion resistance correlation in high chromium cast iron: a digital image processing approach
(AGH University Press, 2026) Vezzania, Ottavia; Fortinia, Annalisa; Gragnaninia, Michele; Sumana, Alessio; Zanini, Nicola
High chromium cast irons (HCCIs) are widely employed as wear-resistant hardfacing materials in industrial applications where solid particle erosion (SPE) represents a primary degradation mechanism, such as in energy production, mining, and cement manufacturing. The erosive wear resistance of these alloys is strongly dependent on the microstructural features of the primary $M_{7}C_{3}$ carbides, particularly their size, morphology, and spatial distribution within the metallic matrix. The quantitative relationship between carbide distribution homogeneity and erosion resistance has received limited attention in the literature. This study investigates the erosive wear resistance of a Fe-Cr-C cast iron hardfacing alloy and proposes three digital image processing methods to quantitatively characterise the carbide microstructure and correlate it with experimental erosion test results. Optical microscopy combined with image binarisation was used to segment primary $M_{7}C_{3}$ carbides. Three methods were adopted: carbide volume fraction (CVF), minimum inter-carbide distances, and a moving scanning area approach. Erosion tests were conducted according to ASTM G76 guidelines using two Arizona road dust powder grades with two mean diameters under equal kinetic energy conditions. Results show that the erosion rate decreases significantly with the increasing erodent particle size and that carbide distribution homogeneity plays a critical role in determining the erosion resistance. The moving scanning area method proved particularly effective at correlating microstructural coverage with experimental erosion rates.
Access status: Open Access ,
Determination of the Heat Transfer Coefficient in the Isothermal Quenching Process of ADI Cast Iron Cooled with Water Mist
(Akademia Górniczo-Hutnicza, 2026) Burbelko, Andriy A.; Stręk, Piotr
Isothermal quenching of austempering cast iron (ADI) castings requires that, after austenitization the casting must be rapidly cooled to the temperature of isothermal austenite decomposition. The cooling rate throughout the entire volume of the heat-treated product must be high enough to prevent pearlitic transformation. At the same time, the temperature of the cooled surface must not decrease below the martensitic transformation start temperature Ms. The cooling rate of the casting surface is determined by factors such as the temperature difference between the surface of the cooled casting and the cooling medium, the thermal conductivity of cast iron, the heat transfer coefficient, and the wall thickness of the treated casting. In the case of cooling with water mist, the heat transfer coefficient depends on the temperature of the cooled surface. To control the cooling process of castings using water mist, information about this relationship for the temperature range of 200–800°C is needed. Available scientific publications on this subject contain contradictory data. Therefore, a measuring station was built with the ability to set the temperature of the cooled surface. The station includes a measuring system that allows the measurement of the heat flux flowing from the heating element into the environment. The result of the research is the measurement of the relationship between the temperature of the cooled surface and the heat transfer coefficient. The values obtained will be used in the future to build a numerical model of ADI castings heat treatment. This work may contribute to the future replacement of salt baths (currently used for fast cooling and austempering) with water mist spraying. In this case, the low-temperature operation of austenite decomposition can be performed without the use of salt a bath.
Access status: Open Access ,
Comparison of component properties between HPDC and rheocasting applying the RheoMetal$^{TM}$ process
(AGH University Press, 2026) Cziegler, Andreas
Since the 1970s, there has been increasing interest in semi-solid processes, allowing improved mould filling with lower gas porosity and lower melt temperatures with improved tool life compared to the standard HPDC process. Challenges lie in the process know-how and the precise temperature control to ensure process stability and reproducibility. In contrast to other semi-solid processes, the RheoMetal$^{TM}$ process achieves the semi-solid state by stirring in an enthalpy exchange material (EEM). This work compares component properties (engine mount) produced by standard HPDC and rheocasting, applying the RheoMetal$^{TM}$ process using an AlSi7MnMg alloy. The results of component testing and radioscopic examination reveal promising outcomes regarding process stability, pore formation, and component properties compared to the standard HPDC process.
Access status: Open Access ,
Quaternionic Quantum Mechanics: the Particles, Their q-Potentials and Mathematical Electron Model
(AGH University Press, 2026) Bożek, Bogusław; Danielewski, Marek; Sapa, Lucjan
In this work we show the quaternionic quantum descriptions of physical processes from the Planck to macro scale. The results presented here are based on the concepts of the Cauchy continuum and the elementary cell at the Planck scale. The structurally symmetric quaternion relations and the postulate of the quaternion velocity have been important in the present development. The momentum of the expansion and compression $u̇_{0}(t, x)$ is the consequence of the scalar term $\sigma_{0}(t, x)$ in the quaternionic deformation potential. The quaternionic $G_{0}(m)(σ_{0} + \hat{\textstyle \phi} )$, vectorial $G_{0}(m) \hat{\textstyle \phi}$ and scalar $G_{0}(m)\sigma_{0}$ propagators are used to generate the second order PDE systems for the proton, electron and neutron. A mathematical model of an electron is formulated. It is described by the hyperbolic-elliptic partial differential system of quaternion equations with the initial-boundary conditions. The boundary conditions are generated by the quaternion energy flux that is found with the use of the Gauss theorem, the Cauchy–Riemann derivative and other mathematical formulas. The rigorous assessment of the second order PDE systems allows the proposal of two second order PDE systems for the $u$ and $d$ quarks from the up and down groups. It was verified that both the proton and the neutron obey experimental findings and are formed by three quarks. The proton and neutron are formed by the $d$-$u$-$u$ and $d$-$d$-$u$ complexes, respectively. The u and d quarks do not comply with the Cauchy equation of motion. The inconsistencies of the quarks’ PDE with the quaternion forms of the Cauchy equation of motion account for their short lifetime and the observed Quarks Chains. That is, they explain the Wilczek phenomenological paradox: Quarks are Born Free, but everywhere they are in Chains.