Silesian University of Technology
  • Gliwice, śląskie, Poland
Recent publications
The aim of this article is to experimentally verify the modified Arrhenius equation for catalytic reactions. The theoretical mathematical reactivity model proposed in the authors’ previous articles assumes that: a) the catalytic reaction rate constant depends not only on the temperature at which the reaction occurs but also on the additional energy supplied to the reactants as a result of the flow of electrons emitted by the catalyst, b) the catalytic reaction rate constant changes in a periodic manner. The research focused on two areas of catalyst applications: controlling tribological processes and converting methanol to hydrogen under visible light irradiation. The article proposes a new interpretation of the earlier findings in tribology and photocatalytic decomposition of methanol. The experimental data show that graphene and nanotubes (CNTs) act as catalysts in tribochemical reactions and that catalytic reactions are initiated by light energy. The key feature of the mechanism by which the nanostructures behave is that they absorb various forms of energy from the surroundings, which are to be stored, transported, or released as pulses back to the surroundings when a catalyzed reaction takes place.
Tephrostratigraphic correlations commonly rely on geochemical composition supported by additional constraints (e.g., multiple stratigraphically ordered tephra, geochronological-stratigraphical constraints, and isotopic determinations), which provide key clues to restrict the number of possible candidates and disambiguate the correlation of a specific tephra among compositionally similar volcanic sources/tephra. However, such additional data may not be available or acquirable, leaving the geochemical data as sole, but challenging viable approach. In this study, two geochronologically poorly constrained late Pleistocene tephra from the eastern Adriatic –from a sand profile on Mljet Island (M-53/2) and from a marine sediment core from Pirovac Bay (PROS 721)– were correlated to known eruptions using only geochemical data (major and trace elements of glass shards), which were treated using both log ratio transformed and raw data. After the statistical treatment of the geochemical data using bivariate plots, linear discrimination analyses and selbal algorithm, the tephra M-53/2 and PROS 721 were suitably correlated with the widespread tephra generated during the Campi Flegrei eruptions of Massereia del Monte (Y-3 marine tephra, 29.0 ± 0.8 ka) and Neapolitan Yellow Tuff (14.5 ± 0.4 ka), respectively. This study showed that the correlation was hardly tenable when using the raw data, as opposed to compositional approach, which yielded satisfactory results. As a consequence, the distribution of Massereia del Monte/Y-3 tephra extended far toward the northeast, while a better chronological model, for reconstructing the paleoenvironmental changes at the Pirovac Bay location and the Holocene sea-level dynamics, could be obtained.
Natural bone constitutes a complex and organized structure of organic and inorganic components with limited ability to regenerate and restore injured tissues, especially in large bone defects. To improve the reconstruction of the damaged bones, tissue engineering has been introduced as a promising alternative approach to the conventional therapeutic methods including surgical interventions using allograft and autograft implants. Bioengineered composite scaffolds consisting of multifunctional biomaterials in combination with the cells and bioactive therapeutic agents have great promise for bone repair and regeneration. Cellulose and its derivatives are renewable and biodegradable natural polymers that have shown promising potential in bone tissue engineering applications. Cellulose-based scaffolds possess numerous advantages attributed to their excellent properties of non-toxicity, biocompatibility, biodegradability, availability through renewable resources, and the low cost of preparation and processing. Furthermore, cellulose and its derivatives have been extensively used for delivering growth factors and antibiotics directly to the site of the impaired bone tissue to promote tissue repair. This review focuses on the various classifications of cellulose-based composite scaffolds utilized in localized bone drug delivery systems and bone regeneration, including cellulose-organic composites, cellulose-inorganic composites, cellulose-organic/inorganic composites. We will also highlight the physicochemical, mechanical, and biological properties of the different cellulose-based scaffolds for bone tissue engineering applications.
This paper presents an experimental and numerical investigation of the performance of a sorbent polymer composite (SPC) material used for removing mercury from the flue gases in a full-scale industrial installation. The investigated material is an attractive alternative to activated carbon, which is commonly used for this purpose. While the application of the SPC is characterized by high capital expenditures, this technology offers not only very low operating expenditures but also high efficiency. This study investigates the SPC’s mercury reduction capabilities concerning the most important flow parameters such as gas velocity, temperature, humidity, and mercury concentration. Small scale laboratory experiment was used to tune the kinetic data of the mercury adsorption. The resulting sub-model has been built into the CFD simulations validated against measurements at an industrial installation. The results showed that the most important parameters affecting the mercury reduction efficiency were the gas velocity and mercury content in the sorbent material. Numerical simulation proved that the material absorbs mercury within the entire reasonable operating temperature and humidity ranges, regardless of mercury speciation.
The high entropy AlCoFeNiTi and AlCoFeNiTiSi alloys were prepared by two methods to determine the influence of the cooling rate on the structure and properties. The Mössbauer spectra of AlCoFeNiTi alloys showed the coexistence of a nonmagnetic part with a magnetic hyperfine portion. The spectra for AlCoFeNiTiSi alloy in an as-cast and plate states contain only nonmagnetic components. The X-ray diffraction analysis confirmed that the silicon addition drastically changes the phase composition of AlCoFeNiTi alloy. Whereas alloy without Si was characterised by the coexistence of L21 and BCC phases, the addition of silicon resulted in the formation of Ti-rich HCP and Al-rich B2 phases. AlCoFeNiTi plate exhibits a high saturation magnetisation value of 29.83 emu/g and the best corrosion resistance (polarisation resistance of about 38.6 kΩcm² and corrosion current density of 0.77 μA/cm²). The highest hardness (1096 HV) was achieved for AlCoFeNiTiSi plate, which is related to the phase composition changes generated by Si addition. The influence of the Si addition on the properties of studied alloys was also confirmed in the decolourisation of Rhodamine B using a modified photo-Fenton process. The decolourisation efficiency within 60 minutes was 92% for AlCoFeNiTiSi alloy, and 95.5% for the AlCoFeNiTi alloy.
Colluvisols represent a significant part of the erosional catena in undulating landscapes, often changed by long-term agricultural management. The present study provides a detailed description of the stratigraphy, properties and development of colluvial profiles in two geologically, climatically and historically different areas of Czechia, situated in the loess region of South Moravia and Central Bohemian Upland, built on plutonic rocks. For the first time in Czechia, colluvial profiles were dated and interpreted in terms of the history of human impact on the landscape and Holocene climatic fluctuations. Four profiles were excavated in the toe-slope and side valley areas. A multidisciplinary approach combining absolute dating by optically stimulated luminescence, assessing ¹³⁷Cs activity and micromorphological, mineralogical and geochemical analysis was applied to identify the period and mode of deposition of each layer. In both areas, a predominantly rapid, event-based sedimentation with thick recently deposited layers was identified in the toe-slopes, while the side-valleys are characterized by gradual, slower and older sedimentation. Peaks of erosion activity at both plots were distinguished in the High and Late Middle Ages and the recent period since 1950. In both periods, significant changes in anthropogenic pressure on the landscape, whether due to increased population density or agricultural intensification, were identified as the main trigger. Nevertheless, significant associations were also found with climatic events in the periods in question. In both areas, colluvial layers corresponding to the pre-Neolithic period were also found, probably exclusively associated with the influence of contemporary climate.
Water droplet formation and growth in the nucleation process are crucial aspects of steam condensation in moist air flow, and they are accompanied by intensive heat exchange between phases. This study proposes a mathematical model for predicting heat transfer coefficients in the condensation process, which is applicable for single-phase and multiphase flows. The proposed model based on the correction function forms a continuous model for the low Knudsen number regime, and in the region of large Knudsen numbers, it employs a simplified droplet growth model based on Hertz and Knudsen's approach derived from the kinetic theorem. The proposed model was compared with existing models based on the continuous approach, that is, models derived by Gyarmathy, Fuchs-Sutigin, and Young, as well as models based on the kinetic theorem. Furthermore, the proposed model was implemented into a numerical CFD tool, and numerical studies were conducted for two representative cases of single-species and multispecies flows, that is, steam and humid-air expansion in a converging-diverging nozzle. For steam studies, the proposed model showed a similar convergence with the experiment as Young's model however, its agreement with the experimental results for multispecies condensation flow was better. The proposed model is promising for the study of condensation when there is rapid droplet growth, which occurs in multispecies flows, even if further study is needed to find a correlation between the condensation coefficient and fluid properties.
A novel analytical formula is introduced for calculation the average longitudinal airflow velocity in tunnels as a result of the piston effect. Existing correlations were analyzed and reworked to better represent the piston effect of vehicles travelling in bulk, which allows relating the airflow velocity to not only average vehicle velocity, but also the traffic intensity and the traffic structure. The approach was validated using the recorded bulk data for an urban road tunnel located in Gdańsk (Poland). Air velocity, weather conditions, wind parameters at tunnel portals, traffic intensity and structure as well as average traffic speed by lane were recorded at 1 s intervals, and analyzed in form of 10 s and 5 min averages. Since ambient conditions may affect the flows inside the tunnel, their impact on flow measurements was studied with a numerical model of the tunnel portals. Despite its simplicity, the proposed model accurately predicted the air velocity due to vehicle movement. The significance of this approach is related to the ease of achieving the initial data, which allows for easy implementation in tunnel ventilation design, risk assessment methods, determination of initial conditions for fire related CFD analyses, continuous tunnel management or estimation of the potential of energy recuperation from airflow within the tunnel. The mean absolute error (MAE) of calculated air velocity to measurements was 0.28–0.38 m/s, with mean average percentage error (MAPE) of 7.8–10.9 %. The determination coefficient for the relation with the measured data was significantly over 0.9.
This study presents a comprehensive proposal for multicriteria optimization of the energy requirement of a multi-story hotel structure, which benefits economically and environmentally. EnergyPlus has been exercised for simulation of a given hotel building and to analysis energy demand. Besides, to implement optimization of building parameters, “Non-dominated Sorting Genetic Algorithm” (NSGA) was applied in JEPlus + EA software. Three building-related parameters have been investigated to optimize energy consumption after sensitivity analysis calculations: building orientation, overhang tilt angle, and overhang depth. Multi-objective optimization has been applied, considering three objectives with equal weight allocated to each factor. These criteria include the energy consumption of heating, cooling, and electrical equipment. The results of multi-objective optimization in the climatic zone of Tehran, show that the total energy demand is reduced by about 118 GJ annually. Furthermore, the long-time saved cost as a result of the optimization is proposed to be invested in the photovoltaic solar system's installation to make the building more sustainable. According to the result derived from Homer Pro software, 2.39 % of the hotel's annual energy consumption will be provided from clean energy. Despite the high cost of renewable energy systems, the costs related to producing electricity reduced significantly.
An important step to achieve low-emission production is the integration of solar energy into industrial processes for decarbonizing the industrial sector. It is therefore necessary to attempt to minimize the cost of these solar industrial process heat systems. The article presents a strategy to reduce the investment costs and thus increase the popularity of parabolic trough collectors by partially replacing the expensive selective coating with a high absorptive, low-cost, non-selective coating in the initial sections of the solar loop where the heat transfer fluid temperature is lower. The analysis was performed for 4 case studies reflecting commercially available solutions with varying temperature ranges for different industrial applications. Calculations were performed using the two-dimensional developed mathematical model that validated with experimental data. The assumed heat transfer fluid is Therminol VP-1. The results have shown the potential of partial use of the Pyromark coating for low and medium-temperature industrial process heat systems with inlet–outlet temperature ranges of 60–120 °C and 100–200 °C. The analysis also showed that all the absorbers can be covered with a low-cost coating in the first scenario. Efficiency increases from 1.5 to 5.5 percentage points have been observed. For the second scenario, 15 of the 24 absorbers can be covered with a low-cost coating, when the installation works at a solar irradiance of 800 W/m². Since the results are depended on the solar irradiance and the chosen regulation strategy of the flow, the final number of absorbers possible to cover with non-selective coating requires a long-term analysis for each case examined.
Despite a considerable progress in the analysis and design of monopiles, many methods are based on complex mathematical structures with doubtful or hard assumptions to verify. Therefore, there is still a need for simple and yet accurate methods for the analysis of monopiles under drained and undrained lateral cyclic loading conditions. In this work, a simple yet efficient two-dimensional modelling approach for the analysis of monopiles is proposed. To account for out-of-plane frictional forces, counter-forces derived from virtual frictional forces generated at the out-of-plane pile interface are applied along the pile length together with the scaled pile stiffness. The predictive capabilities of the proposed approach were validated by back-calculating two different experimental sets. The first consists of a small-scale field monopile test on a coarse-grained soil subjected to lateral cyclic loading under drained conditions. The second is a centrifuge test involving a fine-grained soil subjected to lateral cyclic loading under practically undrained conditions. Simulation results with the proposed approach suggest an accurate prediction of pile displacements and bending moments under both drained and undrained lateral cyclic conditions. The method is, however, unable to reproduce pore water pressures generated behind the pile in low permeability materials.
Environmental monitoring systems enable the collection of information about the various environmental parameters, pollution levels, and the presence of environmental hazards affecting human and marine life. Highly sensitive, stable, and low-power-consuming sensors are vital for such operations. Nanomaterials with different surface morphologies can play a vital role in multiple applications, such as gas sensors, photocatalysts, erosion monitoring, or fine dust sensor. Zinc oxide (ZnO) tetrapod, in particular, shows 3D morphologies that exhibit exciting properties, making them applicable in several device engineering. This work provides a simple yet high-throughput single-step synthesis of ZnO tetrapod with different arm sizes using the flame transport method at various growth conditions. The physicochemical and structural properties have been deeply investigated to shed light on the formation of these 3D structures. The detailed mechanism of the ZnO tetrapod as a gas monitoring material and a photocatalyst has been presented in detail. The sponge-based ZnO gas sensor can selectively sense NO2 gas with a limit of detection (LOD) value of 8.56 ppb. In addition, ZnO tetrapods samples exhibit high photocatalytic activity toward methylene blue and methyl orange degradation under UV illumination. The reaction rate constants of 3.6(2)∙10−4 s−1 and 1.7(1)∙10−4 s−1 are determined for the photocatalytic decomposition of methylene blue and methyl orange, respectively. The results suggest that ZnO tetrapod-based sponges can be a promising material for building next-generation pollution monitoring and degradation systems.
Ventilated cavitating flow features resulting from the air injection at the hydrofoil surface are characterized based on experimental investigation. The experiments have been conducted in the cavitation tunnel at the Silesian University of Technology. The main focus of this work is to investigate how both the location of the injection hole at the surface of the hydrofoil (so-called injection site) and the injection rate have an impact on the cavitating flow in various flow conditions (i.e., different cavitation numbers). The Clark Y hydrofoil is fixed at an 8° angle of attack. In addition, three cavitation numbers, [Formula: see text] = 1.1, 1.25, and 1.6; five air injection rates, Q = 0, 0.25, 0.5, 0.75, and 1 l/min; and two injection sites at the surface of hydrofoil (Tap1-injection and Tap5-injection) are selected for the case studies. Furthermore, the level of dissolved air in water is kept constant at 11.7 mg/l. The unsteady measurements and high-speed imagining declare that, regardless of the injection rate, the injection site has a significant effect on the cavitation dynamic features and morphology. Moreover, it is shown that the effectiveness of air injection depends on the flow conditions.
Artykuł prezentuje główne założenia projektowe, omówienie zakresu i wyników badań w ramach projektu dydaktycznego project-based learning o nazwie: Interdyscyplinarna koncepcja domu mieszkalnego opartego na IDEI 4E – czyli rozwiązaniach energooszczędnych, ekologicznych, ergonomicznych oraz ekonomicznych. Jego głównym celem było opracowanie koncepcji modelowego domu mieszkalnego zakładającego rozwiązania energooszczędne, ekologiczne, ergonomiczne oraz ekonomiczne. Projekt ten został poprzedzony badaniami przedprojektowymi o charakterze interdyscyplinarnym. W zakresie architektury i urbanistyki zostały wykonane badania identyfikacji potrzeb użytkowych, analizy ergonomiczne, urbanistyczne oraz analiza nasłonecznienia. W zakresie budownictwa badania objęły analizy optymalnych rozwiązań technologicznych, konstrukcyjnych i materiałowych, a także podłoża gruntowego. W zakresie inżynierii środowiska i energetyki wykonano analizy rozwiązań systemowych dotyczących nowoczesnej energetyki.
Individual differences in face memory abilities have been shown to be related to individual differences in brain activity. The present study investigated brain-behavior relationships for the N250 component in event-related brain potentials, which is taken as a neural sign of face familiarity. We used a task in which a designated, typical target face and several (high- and low-distinctive) nontarget faces had to be distinguished during multiple presentations across a session. Separately, face memory/recognition abilities were measured with easy versus difficult tasks. We replicated an increase of the N250 amplitude to the target face across the session and observed a similar increase for the non-target faces, indicating the build-up of memory representations also for these faces. On the interindividual level, larger across-session N250 amplitude increases to low-distinctive non-target faces were related to faster face recognition as measured in an easy task. These findings extend the present knowledge about brain-behavior relationships in face memory/recognition and indicate that an advantage in non-intentional encoding of low-distinctive non-target faces into memory goes along with the swift recognition of explicitly learned faces.
The developments on next generation IoT sensing devices, with the advances on their low power computational capabilities and high speed networking has led to the introduction of the edge computing paradigm. Within an edge cloud environment, services may generate and consume data locally, without involving cloud computing infrastructures. Aiming to tackle the low computational resources of the IoT nodes, Virtual-Function-Chain has been proposed as an intelligent distribution model for exploiting the maximum of the computational power at the edge, thus enabling the support of demanding services. An intelligent migration model with the capacity to support Virtual-Function-Chains is introduced in this work. According to this model, migration at the edge can support individual features of a Virtual-Function-Chain. First, auto-healing can be implemented with cold migrations, if a Virtual Function fails unexpectedly. Second, a Quality of Service monitoring model can trigger live migrations, aiming to avoid edge devices overload. The evaluation studies of the proposed model revealed that it has the capacity to increase the robustness of an edge-based service on low-powered IoT devices. Finally, comparison with similar frameworks, like Kubernetes, showed that the migration model can effectively react on edge network fluctuations.
Among different hallmarks of cancer, understanding biomechanics of tumor growth and remodeling benefits the most from the theoretical framework of continuum mechanics. Tumor remodeling initiates when cancer cells seek new homeostasis in response to the microenvironmental stimuli. Cells within a growing tumor are capable to remodel their inter- and intra-connections and become more mobile to achieve a new homeostasis. This mobility enables the tumor to undergo large deformation. In this work, we studied the remodeling of homogeneous tumors, at their early stage of growth, in the context of continuum mechanics. We developed an evolution law for the remodeling-associated deformation which correlates the remodeling to a characteristic tensor of external stimuli. The asymmetric remodeling and the induced mechanical stresses were analyzed for different types of biochemical distributions. To experimentally investigate the model, we studied the remodeling of human glioblastoma (hGB) tumoroids in response to the gradient of nutrients. Using a tumoroid-on-a-chip platform, the degree of remodeling was estimated for the ellipsoidal tumoroids over time. It was observed that higher gradient of nutrients induces higher degree of ellipticity suggesting that the gradient of nutrient is a characteristic property of nutrient distribution that derives the remodeling. We also showed that remodeling gives rise to heterogeneity in cell distribution forming circumferentially aligned cells within the tumors. Compared to the existing studies on tumor growth, our work provides a biomechanical module that relates the remodeling to biochemical stimuli, and allows for large deformation. It also includes experimental component, a necessary but challenging step, that connects the theory and reality to evaluate the practicability of the model.
Individual differences in face memory abilities have been shown to be related to individual differences in brain activity. The present study investigated brain-behavior relationships for the N250 component in event-related brain potentials, which is taken as a neural sign of face familiarity. We used a task in which a designated, typical target face and several (high- and low-distinctive) nontarget faces had to be distinguished during multiple presentations across a session. Separately, face memory/recognition abilities were measured with easy versus difficult tasks. We replicated an increase of the N250 amplitude to the target face across the session and observed a similar increase for the non-target faces, indicating the build-up of memory representations also for these faces. On the interindividual level, larger across-session N250 amplitude increases to low-distinctive non-target faces were related to faster face recognition as measured in an easy task. These findings extend the present knowledge about brain-behavior relationships in face memory/recognition and indicate that an advantage in non-intentional encoding of low-distinctive non-target faces into memory goes along with the swift recognition of explicitly learned faces.
Neutron scattering with isotopic substitution was used to study the structure of concentrated sulfuric acid, and two protic ionic liquids (PILs): a Brønsted-acidic PIL, synthesised using pyridine and excess of sulfuric acid, [Hpy][HSO4]·H2SO4, and a hydrated PIL, in which an equimolar mixture of sulfuric acid and pyridine has been doped with water, [Hpy][HSO4]·2H2O. Brønsted acidic PILs are excellent solvents/catalysts for esterifications, driving reaction to completion by phase-separating water and ester products. Water-doped PILs are efficient solvents/antisolvents in biomass fractionation. This study was carried out to provide an insight into the relationship between the performance of PILs in the two respective processes and their liquid structure. It was found that a persistent sulfate/sulfuric acid/water network structure was retained through the transition from sulfuric acid to PILs, even in the presence of 2 moles (∼17 wt%) of water. Hydrogen sulfate PILs have the propensity to incorporate water into hydrogen-bonded anionic chains, with strong and directional hydrogen bonds, which essentially form a new water-in-salt solvent system, with its own distinct structure and physico-chemical properties. It is the properties of this hydrated PIL that can be credited both for the good performance in esterification and beneficial solvent/antisolvent behaviour in biomass fractionation.
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5,331 members
Henryk Palus
  • Department of Data Science and Engineering
Marek Flekiewicz
  • Department of Automotive Vehicle Construction
Jaroslaw Figwer
  • Institute of Automatic Control
Kishore Kumar Kadimpati
  • Department of Environmental Biotechnology
Grzegorz Nowak
  • Institute of Power Engineering and Turbomachinery
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Akademicka 2A, 44-100, Gliwice, śląskie, Poland
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