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Recent items
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The Influence of Impact Velocity on Stresses and Failure of S355j2 Steel Under Slurry Erosion Conditions
- Dominika Zakrzewska
- Marta H. Buszko
The purpose of this work was to determine the essence of the influence of the impact velocity (5, 7, and 9 m/s) on Hertzian stresses and the erosion mechanism of ferritic-pearlitic S355J2 steel. The investigations were carried out using a slurry pot tester. S355J2 steel showed a strong sensitivity to changes in impact velocity. A significant increase in erosion rate was observed at a velocity of 9 m/s. This increase was 5-fold and over 15-fold compared to velocities of 7 m/s and 5 m/s, respectively. The study of Hertzian stress is crucial in erosion research because it helps understand how impact energy is absorbed by the eroded material and the mechanisms that cause surfacewear. A linear increase in mean contact pressure and maximum shear stress was observed with increasing impactvelocity. The mean contact pressure increased from 4.3 GPa to 5.5 GPa and the maximum shear stress increasedfrom 2.0 GPa to 2.5 GPa. The kinetic energy of the solid particles that hits the eroded steel is distributed in the con-tact area, which leads to various deformations and wear mechanisms. The primary type of deformation was fatiguedegradation of the surface layers of the eroded steel. The high kinetic energy of solid particles contributed to theformation of plastic deformations and strongly deformed steel flakes. Higher impact velocities generally result ingreater forces and contact stresses on the material surface. This led to the intensification of plastic deformation inthe contact areas and increased the Hertzian stresses.
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The influence of the geographic positioning system error on the quality of ship magnetic signature reproduction based on measurements in sea conditions
- Jarosław Tarnawski
- Krystian Buszman
- Mirosław Wołoszyn
- Bartosz Puchalski
In previous studies, the authors performed the magnetic signature reconstruction of the marine ship Zodiak as part of the measurement campaign focused on recording magnetic data and the relative position of a ship during its passage over a magnetometer immersed on the testing ground. A high degree of representation of the magnetic signature was obtained. However, the recorded measurement data revealed new patterns of the multidipole model behavior that were not observed in the synthetic data based analyzes. It was assumed that the main factor influencing the abovementioned behavior of the model is the error in determining the geographical position of the ship in relation to the magnetometer. Therefore, another research was carried out to determine the relative position of the ship and the measurement device in sea conditions, in the area of the test site used in the previous study. For this purpose, two different classes of GPS receivers were used. The first receiver was the same as that used to determine the position of Zodiak in the previous measurement campaign, while the second receiver, treated as a reference, was a top-class geodetic receiver. The difference in indications between these two receivers gave a picture of the scale of errors in the data recorded during the previous measurement campaign. These errors are used in the article to analyze the effect of inaccuracies in determining the ship position on the quality of magnetic signature reproduction. Two types of signature reproduction error were introduced – the error based only on the data collected from the ship’s paths, and the error in the entire area of magnetic anomaly. The model of Zodiak was used to determine the value of the magnetic flux outside the paths. Profiles of differences in indications of GPS receivers at sea which were obtained from actual measurements were used to analyze the errors in determining the ship position. A measurable result of the work reported in the article is the map of the loss of quality of magnetic signature reproduction as a function of the ship position determination error, which can indicate the range of applicability of the model and the described method.
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The influence of α,ω-diols and SiO2 particles on CO2 absorption and NH3 escaping during carbon dioxide capture in ammonia solutions
- Temesgen Amibo
- Donata Konopacka-Łyskawa
Ammonia solutions are widely used solvents for CO2 capture. However, a significant disadvantage of these solvents is secondary pollution of the purified gas stream by desorbed ammonia. In this work, α,ω-diols, and colloidal silica have been proposed to reduce this undesired effect. Ammonia solutions with the addition of ethylene glycol (EG), 1,3-propanediol (PRD), 1,4-butanediol (BUD), 1,5-pentanediol (PED), or 1,6-hexanediol (HED) and ammonia solution with the addition of diol and colloidal SiO2 were tested. The concentration of CO2 and NH3 in the exhaust gas was continuously measured during the experiments. Based on the recorded measurements, the number of moles of CO2 absorbed and the number of moles of NH3 lost were calculated. Mass transfer coefficients for CO2 absorption and NH3 desorption were also determined. The studies showed that CO2 absorption occurred faster in ammonia solutions with EG, PRD, BUD, and HED, and the CO2 loading was higher than in pure NH3 solution. The most effective additive improving CO2 absorption was BUD, followed by HED. SiO2 particles improved slightly the absorption efficiency in most of the tested diol solutions. All diols used inhibited the escape of ammonia, with PED having the most effective effect. However, adding silica particles effectively inhibited ammonia escape in all tested systems.
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The Input of Nanoclays to the Synergistic Flammability Reduction in Flexible Foamed Polyurethane/Ground Tire Rubber Composites
- Aleksander Hejna
- Paulina Kosmela
- Adam Olszewski
- Wiktoria Żukowska
Currently, postulated trends and law regulations tend to direct polymer technology toward sustainability and environmentally friendly solutions. These approaches are expressed by keeping materials in a loop aimed at the circular economy and by reducing the environmental burdens related to the production and use of polymers and polymer-based materials. The application of recycled or waste-based materials often deals efficiently with the first issue but at the expense of the final products’ performance, which requires various additives, often synthetic and petroleum-based, with limited sustainability. Therefore, a significant portion of research is often required to address the drawbacks induced by the application of secondary raw materials. Herein, the presented study aimed to investigate the fire performance of polymer composites containing highly flammable matrix polyurethane (PU) foam and filler ground tire rubber (GTR) originating from car tire recycling. Due to the nature of both phases and potential applications in the construction and building or automotive sectors, the flammability of these composites should be reduced. Nevertheless, this issue has hardly been analyzed in literature and dominantly in our previous works. Herein, the presented work provided the next step and investigated the input of nanoclays to the synergistic flammability reduction in flexible, foamed PU/GTR composites. Hybrid compositions of organophosphorus FRs with expandable graphite (EG) in varying proportions and with the addition of surface-modified nanoclays were examined. Changes in the parameters obtained during cone calorimeter tests were determined, discussed, and evaluated with the fire performance index and flame retardancy index, two parameters whose goal is to quantify the overall fire performance of polymer-based materials.
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The Interplay between Endogenous and Foodborne Pro-Oxidants and Antioxidants in Shaping Redox Homeostasis
- Patrycja Jakubek
- Karol Parchem
- Mariusz R. Wieckowski
- Agnieszka Bartoszek-Pączkowska
Oxidative stress has been known about in biological sciences for several decades; however, the understanding of this concept has evolved greatly since its foundation. Over the past years, reactive oxygen species, once viewed as solely deleterious, have become recognized as intrinsic components of life. In contrast, antioxidants, initially believed to be cure-all remedies, have failed to prove their efficacy in clinical trials. Fortunately, research on the health-promoting properties of antioxidants has been ongoing. Subsequent years showed that the former assumption that all antioxidants acted similarly was greatly oversimplified. Redox-active compounds differ in their chemical structures, electrochemical properties, mechanisms of action, and bioavailability; therefore, their efficacy in protecting against oxidative stress also varies. In this review, we discuss the changing perception of oxidative stress and its sources, emphasizing everyday-life exposures, particularly those of dietary origin. Finally, we posit that a better understanding of the physicochemical properties and biological outcomes of antioxidants is crucial to fully utilize their beneficial impact on health.
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The KLC Cultures Synergy for Organizational Agility. Trust, Risk-Taking Attitude, and Critical Thinking as Moderators
- Wioleta Kucharska
- Maciej Kucharski
- Tomasz Balcerowski
Organizational agility is visible in organizational change adaptability, and it is based on the development of dynamic capabilities, strategic sensitivity of leaders, accuracy and timing of decision-making, learning aptitude, flexibility in thinking and acting, and smooth resource flow across organizations, including the knowledge resource. In such a context, this study aimed to expose how the knowledge, learning, and collaboration cultures approach (KLC) supports organizational agility when this relation is moderated by mutual trust among employees, risk-taking attitude, and critical thinking abilities. Based on the sample composed of 640 Polish knowledge workers and data analyzed with the structural equation modeling method (SEM), this study's results proved that the KLC culture synergy supports organizational agility building and that the mistakes acceptance component of learning culture is critical. Moreover, trust among workmates, risk-taking readiness, and critical thinking skills are significant mediators. The key novelty was exposed through the negative influence of a risk-taking attitude (uncertainty acceptance) on agility. Precisely, the lack of risk acceptance or, reversely, the risk-avoidance attitude supports agility. This is because agility, understood as smooth adaptability, is the effect of efficient risk management. Thanks to risk management and critical thinking, the negative impact of inaction risks can often be seen as higher than the risks of very innovative actions. The KLC approach, critical thinking, and trust among workmates support the smooth selection of risks that must be taken in today's dynamic business. Risk is inevitable. So, from this point, the essence of agility is the ability to smoothly and wisely select among risks that should be taken or avoided. In summary, agility can be considered to be the smooth selection of acceptable risks
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The KLC Cultures' Synergy Power, Trust, and Tacit Knowledge for Organizational Intelligence
- Wioleta Kucharska
- Denise A. D. Bedford
This paper examines the impact of knowledge, learning, and collaboration culturessynergy (the KLC approach) on organizational adaptability. The SEM analysis method was applied to verify the critical assumption of this paper: that the KLC approach and trust support knowledge-sharing processes (tacit and explicit) and are critical for organizational intelligence activation.Specifically, the empirical evidence, based on a 640-case sample composed of Polish knowledge workers, revealedthat knowledge sharing, organizational intelligence, and innovativeness are vital benefits of the KLC cultures’synergy. It also highlighted that trust among workmates is critical to sustaining tacit knowledge sharing in an organization. Tacit knowledge, which is knowledge that is difficult to transfer to another person by means of writing it down or verbalizing it, is clearly identified as a key component of change adaptability, which is viewed as a measure oforganizational intelligence. Moreover, the acceptance of mistakesas a learning source -a learning culturecomponentthat supports trial-error learning,was found to betremendous for knowledge-sharing processes, organizational intelligence (change adaptability),and innovativeness. Thisstudyproved that knowledge sharing, organizational intelligence, and innovativeness are vitalbenefits of the synergy that offers the KLC cultures. Trust strengthens this effect. So, to gain these benefits, knowledge-driven organizations should employ trusted managers who trust others and, in addition to their professional credentials, exhibit strong habits of respecting knowledge, learning, and collaboration.
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The landscape in the informal education of the youngest
- Marta Koperska-Kośmicka
The European Landscape Convention, adopted in 2000, aims to promote the protection, management and planning of landscapes and to organise cooperation on landscape-related issues. Countries that ratified the Convention undertook to introduce activities that would promote public education on the subject. In Poland, the Ministry of Education has identified schools as the place to implement these priorities. In the core curriculum of general education for primary schools, «creating opportunities to learn about the components of the landscape» was prescribed as the primary objective of the subject of nature. Although the school should play a leading role in the implementation of these tasks, even in its most elaborate form it is unable to meet all the needs. It should be complemented by non-formal education, which goes beyond the school curriculum and is a kind of its extension. This article is an attempt to present and evaluate the author’s educational project dealing with the topic of cultural landscape at the regional level.
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THE METHODS OF TEACHING / LEARNING STRUCTURAL MECHANICS
- Marek Skowronek
Structural mechanics is a key issue to study for engineers. A high rank and high social responsibility profession requires both a high graded and intuitive approach. The evolution of learning / teaching methodology follows the novel technical achievements of every decade. The aim remains the same: to produce a professional to perform advanced relevant analysis and safe, optimal structural design
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The pulse width modulation strategy for a five-phase three-level NPC voltage source inverter with DC-link voltage balancing ability
- Dmytro Kondratenko
The doctoral dissertation is all about the development of the space vector modulation algorithm for controlling the generation of output voltage vectors in a three-level, five-phase NPC inverter. The developed algorithm can be used to control five-phase motors, where it will be possible to increase the motor torque by 15%; by appropriate injection of 3rd harmonic current. The proposed control approach also opens up the possibility of independent control of two electric motors, supplied from a single inverter. The critical issues that need to be solved when creating pulse-width modulation algorithms for multiphase, three-level inverters are the need to simultaneously balance the input splitting DC-link capacitor voltages and ensure correct generation of many independent voltage vectors. This scenario is also applicable to the case when the DC-link voltages are of different values. The proposed solution paves way for independent syntheses of output voltages with minimum number of active switches’ transitions; while allowing for appropriate voltage distribution on the DC-link capacitors.
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The relative cup-length in local Morse cohomology
- Thomas O. Rot
- Maciej Starostka
- Nils Waterstraat
Local Morse cohomology associates cohomology groups to isolating neighborhoods of gradient flows of Morse functions on (generally non-compact) Riemannian manifolds M. We show that local Morse cohomology is a module over the cohomology of the isolating neighborhood, which allows us to define a cup-length relative to the cohomology of the isolating neighborhood that gives a lower bound on the number of critical points of functions on M that are not necessarily Morse. Finally, we illustrate by an example that this lower bound can indeed be stronger than the lower bound given by the absolute cup-length.
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THE REPRESENTATION PROBLEM FOR A DIFFUSION EQUATION AND FRACTAL R-L LADDER NETWORKS
- Jacky Cresson
- Anna Szafrańska
The representation problem is to prove that a discretization in space of the Fourier transform of a diffusion equation with a constant diffusion coefficient can be realized explicitly by an infinite fractal R-L ladder networks. We prove a rigidity theorem: a solution to the representation problem exists if and only if the space discretization is a geometric space scale and the fractal ladder networks is a Oustaloup one. In this case, the resistance and inertance of the ladder are explicitly determined up to a constant.
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The role of governance to support smart community development: a systematic literature review
- Magdalena Ciesielska
- Gabriela Viale Pereira
This paper studies the interaction between the smart community and smart governance concepts to elaborate on the role of governance to support local governments in developing smart communities’ strategies and solutions. We perform a systematic literature review to analyse how the concept of smart community has advanced in terms of its definitions, context, benefits, challenges, and enablers and propose a unified term with a focus on the governance aspects. The review highlights that some conceptualizations of smart communities have a more technical perspective that evolved towards a socio-technical concept, being information and communication technologies a mediator to behaviour change and a tool to improve decision-making and citizen-centricity, as well as promoting social governance.
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The role of microbial coagulants on the physicochemical, proteolysis, microstructure and sensory properties of low-fat Edam cheese manufactured from ultrafiltered buffalo milk
- Safaa A.M. El-Aidie
- Roberto Castro Munoz
- Basim Abu-Jdayil
- Samia M. El-Dieb
This work investigates the influence of using microbial coagulants, including Rhizomucor miehei (MCR) protease and Cryphonectria parasitica (MCC) protease, on the quality characteristics of low-fat Edam cheese made from ultrafiltered buffalo milk (LFUE). Concurrently, a benchmark with calf rennet (CR) has been also performed. Throughout a 90-day ripening period, the cheeses were assessed for their physicochemical features, proteolysis, texture, free amino acid and free fatty acid content, microstructure, and sensory attributes. The study revealed that both microbial coagulants had no significant impact on the physicochemical composition and firmness of the cheeses while slightly affected the free fatty acids. Cheeses made with microbial coagulants displayed higher proteolysis, with MCR and MCC cheeses exhibiting greater levels of water-soluble nitrogen and 12% trichloroacetic acid-soluble nitrogen than CR cheese. MCR and MCC cheeses exhibited more extensive breakdown of αs- and β-caseins, as indicated by the SDS-PAGE electrophoretogram, compared to CR cheese during ripening. As for the proteolytic activity, the microbial coagulant contributed to shaping the free amino acid content, microstructure, and sensory qualities of the cheeses. Notably, MCC cheese outperformed MCR or CR cheeses in terms of free amino acid levels. MCR and MCC cheeses resulted in smooth microstructures with uniform protein networks as observed by microscopy, while CR cheese displayed rough, granular surfaces. With the highest scores for appearance, body, texture, and flavor, MCC cheese demonstrated superior sensory properties compared with MCR and CR cheeses.
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The role of resilience in explaining hotel growth: A fuzzy-set QCA approach
- Diana Dryglas
- Anna Lis
- Marcin Suder
Purpose: Due to the detrimental effects of the recent pandemic on the hotel sector, hotel resilience research and its impact on hotel recovery have received lots of academic attention. However, a sustainable perspective on hotel resilience, as an approach for investigating its impact on long-term hotel growth, has been largely overlooked in the hospitality resilience literature. Therefore, this paper aims to address the research gap by identifying the configuration of factors that constitute sustainable hotel resilience leading to the growth of selected hotels operating in Poland. Methodology: Data for analysis were obtained from surveys conducted with the participation of 120 managers of one- and two-star hotels. To achieve the goal, a fuzzy-set qualitative comparative analysis (fsQCA) was chosen, which belongs to the group of configurational analysis methods. Findings: Due to the asymmetric nature of the method, the analysis reveals configurations both of factors leading to high hotel growth and those leading to low growth. In both cases, two such factor configurations were obtained. For high levels of hotel growth, it was found that maintaining a high level of three factors simultaneously, namely employee resilience, CSR activities and leadership resilience or CSR activities, team resilience and leadership resilience, provided sufficient conditions. On the other hand, for low levels of growth, fsQCA indicated sufficient conditions in the form of a low level of CSR activities and leadership resilience or a low level of employee resilience and team resilience. These findings emphasise the role of combining different factors to improve hotel growth. Implications for theory and practice: The research contributes to the literature on resilience in the hospitality industry by developing a new theoretical perspective on the complex nature of combinations of factors that contribute to sustainable hotel resilience leading to both high and low growth. The research results also provide significant implications for entrepreneurs and managers, indicating the role of different combinations of factors in determining hotel growth. Originality and value: The knowledge regarding sustainable hotel resilience is still insufficient. The study identified the best combinations of factors (both internal and external) that constitute sustainable hotel resilience, which may be vital for hotel growth.
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The role of the combined nitrogen-sulfur-carbon cycles for efficient performance of anammox-based systems
- Dominika Derwis
- Hussein Al-Hazmi
- Joanna Majtacz
- Przemysław Kowal
- Slawomir Ciesielski
- Jacek Mąkinia
The combined anammox/mixotrophic denitrification process was conducted in two granular sequencing batch reactors (SBRs) during a 200-day operation. Both reactors were fed with synthetic medium, but SBR2 was enriched with additional sulfate (SO4 2 ) which influenced sulfate reduction ammonium oxidation (SRAO) and heterotrophic reduction of SO4 2 by sulfate reducing bacteria. It was hypothesized that the addition of SO4 2 could positively impact the removal rates of N-S-C compounds. A low C/N ratio (0.4–1.6) was maintained to prevent inhibition of anaerobic ammonium oxidizing bacteria (AnAOB), and alternating chemical oxygen demand (COD) on/off conditions were used to regenerate AnAOB during COD-off phases and heterotrophic denitrifiers during COD-on phases. Stoichiometric analysis showed that introducing SO4 2 in SBR2 enhanced the ammonium utili zation rate, which was approximately 10 % higher compared to SBR1 in the final stage of the experiment (25.8 vs. 22.8 mg N/(g VSS⋅h)). The total nitrogen removal efficiencies ranged from 62 % to 99 % in both reactors, with SBR2 consistently exhibiting approximately 4 % higher efficiency than SBR1. In SBR2, the maximum overall SO4 2 utilization efficiency reached 27 % under COD-off conditions, while overall COD utilization was almost complete under COD-on conditions. A strong correlation (R2 =0.98) was observed between SO4 2 production and COD utilization. The key players responsible for N and S transformations in response to SO4 2 addition were Candidatus Brocadia and Chloroflexi - Anaerolineae. This study highlights the potential to enhance the overall efficiency of N-S-C removal by implementing an integrated anammox/mixotrophic denitrification process. The combination of cycles emerges as a sustainable approach for treating wastewater rich in N-S-C compounds.
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The scope of fiscal decentralisation in EU countries: a comparative analysis
- Alicja Sekuła
- Karol Flisikowski
Motivation: Decentralization is one of the main challenges in public sector reform. In democratic countries the level of decentralisation in individual countries is not identical. The varying scope of decentralization affects the quality, quick and efficient decision-making by public leaders. Aim: Comparison of the extent of fiscal decentralisation in EU Member States; creation of groups of states with similar levels of decentralisation; identification of characteristics of countries where the average level of decentralisation is similar. Results: As a result of the study 4 clusters were created. The first includes centralized countries (small area, small population, e.g. Malta, Cyprus). The level of decentralization is a little bit higher in federal states and most of the countries that joined the EU in 2004 or later (cluster 2, the most numerous). Larger and more numerous countries are characterized by a higher level of decentralization (cluster 3, e.g. Italy, Poland, France). Clusters 4th is composed of the Nordic countries, i.e. in countries where a welfare state model with an extensive public sector has been implemented. As a result, it was found that the level of decentralization is related to the size of the country, population and political system.
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The shape of an ROC curve in the evaluation of credit scoring models
- Błażej Kochański
The AUC, i.e. the area under the receiver operating characteristic (ROC) curve, or its scaled version, the Gini coefficient, are the standard measures of the discriminatory power of credit scoring. Using binormal ROC curve models, we show how the shape of the curves affects the economic benefits of using scoring models with the same AUC. Based on the results, we propose that the shape parameter of the fitted ROC curve is reported alongside its AUC/Gini whenever the quality of a scorecard is discussed.
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The Smith-Watson-Topper parameter and fracture surface topography relationship for additively manufactured 18Ni300 steel subjected to uniaxial variable-amplitude loading
- Wojciech Macek
- Zbigniew Marciniak
- Grzegorz Lesiuk
- Przemysław Podulka
- Cho-pei Jiang
In this paper, the association between Smith-Watson-Topper (SWT) parameter and fracture surface topography is studied in additively manufactured maraging steel exposed to variable-amplitude fatigue loading. The post-failure fracture surfaces were examined using a non-contact 3D surface topography measuring system and the entire fracture surface method. The focal point is on the correspondence between fatigue characteristics, articulate by the SWT parameter, and the fracture surface topography features, represented by areal, volume, and fractal dimension parameters. A fatigue life prediction model based on SWT and fracture surface topography factors is proposed. The presented model expresses good compliance with fatigue test results. This model can be useful for post-mortem analysis of engineering elements under variable-amplitude loading fatigue, especially for materials produced by additive manufacturing (AM).
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The study on the appearance of deformation defects in the yacht lamination process using an AI algorithm and expert knowledge
- Paweł Szalewski
- Tacjana Niksa-Rynkiewicz
- Mariusz Deja
This article describes the application of the A-priori algorithm for defining the rule-based relationships between individual defects caused during the lamination process, affecting the deformation defect of the yacht shell. The data from 542 yachts were collected and evaluated. For the proper development of the algorithm, a technological process of the yacht lamination supported by expert decisions was described. The laminating technology is a complex process of a sequential application of individual laminates according to a special strategy. The A-priori algorithm allowed for obtaining the set of association rules defining the relationships between the defects resulting from the lamination process and influencing the deformation defect of the yacht shell, which is one of the most common errors in yacht production. The obtained aggregated rules were compared with the expert knowledge of the employees of the production, quality control, mould regeneration, and technology departments of the yacht yard. The use of the proposed A-priori algorithm allowed for the generation of relationship rules consistent with the general opinion of experts. Associative rules additionally took into account detailed causes of a specific error, which were not always noticed by employees of specific departments. The assessment of the lamination process using an artificial intelligence algorithm turned out to be more objective, which made it possible to gradually reduce the total number of errors occurring in the yacht shell lamination process, and thus shorten the time needed to repair errors and the total time of producing the yacht.
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The Timber economy in the Baltic Sea, 1600-1939
- Luciano Segreto
The work analyses the evolution of the timber economy in the Baltic Sea from the 17th century until WW2
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The (Un)Real City by Magdalena Abakanowicz: Guidelines for Cities in Times of Planetary Crisis
- Izabela Mironowicz
Three decades have passed since Magdalena Abakanowicz presented her concept of Bois de Nanterre — Arboreal Architecture, in response to a call for a broader reflection on approaches to urban landscaping and a reinterpretation of the meaning and evolution of the Grand Axis in Paris. This paper analyses the work presented by the artist from an urban planning perspective. It shows how the rich and multi-layered metaphor for the 21st-century city, embodied in the concept of the Bois de Nanterre, offers a pioneering and radical lesson for addressing contemporary urban problems.
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The use of a 4 PB strain sweep fatigue test to evaluate characteristics of carbon grid reinforced asphalt beams
- Marcin Stienss
- Piotr Jaskuła
- Cezary Szydłowski
The article presents research results concerning pre-bituminized carbon grids for asphalt pavement reinforcement, which are used to prevent cracking and crack reflection thus increasing bearing capacity and durability of pavement. Research program involved testing of large sized double-layer samples, both reinforced and unreinforced. The advantage of using a carbon grid was especially visible after crack initiation. The energy during crack propagation phase was about three times higher in comparison with unreinforced samples. The maximum dissipated energy was significantly higher in the fatigue test for a reinforced samples, with also higher level of tensile strain.
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The use of a genetic algorithm in the process of optimizing the shape of a three-dimensional periodic beam
- Łukasz Doliński
- Arkadiusz Żak
- Wiktor Waszkowiak
- Paweł Kowalski
- Jacek Szkopek
Mechanical periodic structures exhibit unusual dynamic behavior thanks to the periodicity of their structures, which can be attributed to their cellular arrangement. The source of this periodicity may result from periodic variations of material properties within their cells and/or variations in the cell geometry. The authors present the results of their studies on the optimization of physical parameters of a three-dimensional axisymetrical periodic beam in order to obtain the desired vibroacoustic properties. The aim of the optimization process of the unit cell shape was to obtain band gaps of a given width and position in the frequency spectrum.
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The use of chain extenders as processing aids in the valorization of single-use polylactide (PLA) products by rotomolding
- Mateusz Barczewski
- Joanna Aniśko
- Aleksander Hejna
- Mariusz Marć
- Marta Safandowska
- Krzysztof Lewandowski
- Zaida Ortega
- Patryk Mietliński
- Jacek Andrzejewski
Biodegradable plastics in single-use products have increased in popularity as a way to reduce the negative environmental impact of conventional plastics and meet the tightening law regulations. However, their recyclability needs to be assessed, as the environmental behavior of single-use plastics, even if compostable, is not negligible. Polylactide (PLA) is susceptible to thermal, oxidative, hydrolytic, and mechanical degradation during reprocessing, so the conditions of such cycles must be accurately controlled. The necessity of using additives to reduce such degradations during rotational molding, a process with long cycle times and oxidizing atmosphere, has been demonstrated. Chain extenders based on a carbodiimide (Bioadimide® 100 - KI), a methylene diphenyl diisocyanate (MDI), and a polystyrene-acrylic copolymer (Joncryl® ADR-4368c - J) have been added to postconsumer PLA wastes. It has been demonstrated that these three chain extenders enabled obtaining a higher molecular weight of the reprocessed polymer, compared to the ~50% reduction for the neat PLA. The use of carbodiimide yielded the most similar performance to that of unprocessed raw material. All samples provided adequate thermal stability and processing parameters for the rotational molding. Carbodiimide is considered the most efficient additive, as it increases the molecular mass of the polymer as it remains unchanged after processing. Similarly, KI-modified PLA rheological behavior remains unchanged after processing, which means this compound can reduce thermooxidative and hydrolytic degradation reactions. Thus contributing to the achievement of improved processability and better performance; in particular, impact strength increased from 1.06 ± 0.56 for PLA to 8.12 ± 2.28 kJ/m2 for KI-modified PLA, and toughness of 5.36 ± 1.61 to 61.49 ± 8.01 J/ mm3, respectively, leading to rotomolded items without structural defects. On the opposite, the use of Joncryl® and MDI led to structural defects in the rotomolded parts despite a higher molecular weight of the polymer, which resulted in poor mechanical properties, although better than PLA without any additive. All three chain extenders resulted in an amorphous PLA structure with increased glass transition temperature and improved thermal stability, which correlated with the reduced emissions of volatile compounds compared to neat recycled PLA.
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The Use of Cluster Analysis to Assess the Wear Resistance of Cermet Coatings Sprayed by High Velocity Oxy-Fuel on Magnesium Alloy Substrate
- Ewa Stanisława Jonda
- Dariusz Fydrych
- Leszek Łatka
- Hanna Myalska-Głowacka
Cermet coatings are one of the best surface protection of machine elements against wear. On the other hand, the most universal and economically justified method of applying such coatings is high velocity oxy-fuel (HVOF) spraying. This method makes it possible to produce coatings characterized by compact structure, low porosity and very good adhesion to the substrate. All these fundamental properties contribute to the high wear resistance of these coatings. However, carrying out full wear tests (e.g. ball-on-disc) is time-consuming, especially when it is necessary to select the proper feedstock material and carefully selected process parameters. The aim of the following researches was to statistically investigate the possibility of replacing long-term wear resistance tests with estimation of this performance on the basis of determining the fundamental mechanical properties of the coatings. Three types of coating materials were selected: WC-12Co, WC-10Co-4Cr and WC-20Cr3 C2 -7Ni, which were deposited on AZ31 magnesium alloy substrates from three different spray distances: 320, 360 and 400 mm. On the basis of the tests carried out and using cluster analysis techniques (the Ward and k-means methods), the relative similarity between the obtained coatings was determined. The applied methodology allowed to select from the analyzed cermet coatings such samples that were characterized by improved resistance to abrasive wear. The obtained results of the analyzes were also referred to the results of tests of resistance to abrasive wear
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The Use of Ultra-Fast Gas Chromatography for Fingerprinting-Based Classification of Zweigelt and Rondo Wines with Regard to Grape Variety and Type of Malolactic Fermentation Combined with Greenness and Practicality Assessment
- Anna Stój
- Wojciech Wojnowski
- Justyna Płotka-Wasylka
- Tomasz Czernecki
- Ireneusz Kapusta
In food authentication, it is important to compare different analytical procedures and select the best method. The aim of this study was to determine the fingerprints of Zweigelt and Rondo wines through headspace analysis using ultra-fast gas chromatography (ultra-fast GC) and to compare the effectiveness of this approach at classifying wines based on grape variety and type of malolactic fermentation (MLF) as well as its greenness and practicality with three other chromatographic methods such as headspace solid-phase microextraction/gas chromatography-mass spectrometry with carboxen-polydimethylosiloxane fiber (SPME/GC-MS with CAR/PDMS fiber), headspace solid-phase microextraction/gas chromatography-mass spectrometry with polyacrylate fiber (SPME/GC-MS with PA fiber), and ultra performance liquid chromatography–photodiode array detector-tandem mass spectrometry (UPLC-PDA-MS/MS). Principal Component Analysis (PCA) revealed that fingerprints obtained using all four chromatographic methods were suitable for classification using machine learning (ML). Random Forest (RF) and Support Vector Machines (SVM) yielded accuracies of at least 99% in the varietal classification of Zweigelt and Rondo wines and therefore proved suitable for robust fingerprinting-based Quality Assurance/Quality Control (QA/QC) procedures. In the case of wine classification by the type of MLF, the classifiers performed slightly worse, with the poorest accuracy of 91% for SVM and SPME/GC-MS with CAR/PDMS fiber, and no less than 93% for the other methods. Ultra-fast GC is the greenest and UPLC-PDA-MS/MS is the most practical of the four chromatographic methods.
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Theoretical modelling of efficient fire safety water networks by certified domination
- Joanna Raczek
- Mateusz Miotk
This paper explores a new way of designing water supply networks for fire safety using ideas from graph theory, focusing on a method called certified domination. Ensuring a good water supply is crucial for fire safety in communities, this study looks at the rules and problems in Poland for how much water is needed to fight fires in different areas and how this can be achieved at a lowest possible cost. We present a way to plan water supply networks for fire protection as a graph, where each point(node) is a place that needs water, and the lines (links) show where water can go between these points.The main idea is to find the best places to put pumping stations and wells in the network to save money and still meet all the fire safety requirements. Our approach assumes that it costs more to build a pumping station than a well. We use some examples to show how this method can find cost-effectivesolutions for water supply networks, while ensuring that they meet fire safety requirements and are not too expensive to build. This approach is a new and efficient way to improve the design of water supply networks for fire safety. Key challenges that are solved in this paper are a linear time algorithm finding an optimal solution for networks without cycles and a BLP (Binary Linear Programming)algorithm solving the problem in arbitrary networks.
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Therapeutic biomaterials – application in neurology and cardiology
- Klaudia Malisz
- Beata Świeczko-Żurek
Biomaterials are of interest in most medical fields. It's hard to imagine life without them. And due to the ever-increasing demand, scientists are developing new materials. Diseases of the nervous and cardiovascular systems are still a big problem, which are associated with a limited ability to regenerate brain or heart tissues. Therefore, this review discusses the advancement in biomaterial engineering for the treatment of neurological and cardiovascular diseases. Neurodegenerative diseases affect a large percentage of older people. Therefore, the review presents treatment options for Alzheimer's (AD), and Parkinson's diseases (PD). Another serious problem is cardiac ischemia. To regenerate heart tissue, scientists have proposed the use of extracellular vesicles, injectable hydrogels, and biomaterial-based cardiac patches. In addition to tissue engineering, implants are also developing in the field of cardiology. More and more modern materials are being created, e.g., for valve prostheses or vascular stents.
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Thermally activated natural chalcopyrite for Fenton-like degradation of Rhodamine B: Catalyst characterization, performance evaluation, and catalytic mechanism
- Jiapeng Yang
- Kai Jia
- Shaoyong Lu
- Yijun Cao
- Grzegorz Boczkaj
- Chongqing Wang
In this work, catalytic activity of natural chalcopyrite (CuFeS2) was improved by thermal activation. The modified chalcopyrite was used as efficient catalyst for degradation of organic dye Rhodamine B (RhB) through advanced oxidation process (AOP). Effects of catalyst dosage, H2O2 concentration, reaction temperature, solution pH, anions, and natural organic matter on the degradation efficiency of RhB were investigated. This study revealed that thermal activation at 300 °C changed the chemical valency of surface elements rather than transforming the major chemical phase of natural chalcopyrite. The Fenton-like degradation of RhB was significantly improved by thermally activated chalcopyrite. RhB degradation could be obtained under broad pH and showed high resistance to natural organic matter and anions. Under optimal conditions of H2O2 43.0 mM, catalyst 0.75 g/L, initial pH 5.1, and reaction temperature 25 °C, the degradation of RhB reached 96.7% at 50 min. Based on the rate constant of reaction kinetics, the activation energy for RhB degradation was calculated to be 9 kJ/mol. Radical scavenging experiments and electron paramagnetic resonance (EPR) technique demonstrated that RhB degradation was dominated by the generated hydroxyl radicals in activated chalcopyrite/H2O2 system. The formation of surface sulfates resulted from thermal activation induced the dissolved copper or iron ions, and promoted H2O2 activation and facilitated RhB degradation by reactive hydroxyl radicals. This work provides an in-depth understanding of the mechanism behind thermal activation to enhance the activity of natural chalcopyrite, offering a theoretical basis for utilizing natural minerals for Fenton-like treatment of organic wastewater towards cleaner production.
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Thermodynamic Efficiency of an Advanced 4th Generation VHTR Propulsion Engine for Large Container Ships
- Jerzy Głuch
- Tomasz Kodlewicz
- Marta Drosińska-Komor
- Natalia Ziółkowska
- Łukasz Breńkacz
- Paweł Ziółkowski
In response to global initiatives to reduce greenhouse gas emissions, the maritime industry must adopt green propulsion solutions. This paper analyses the operational potential of very high-temperature reactors (VHTRs) as an innovative propulsion source for large container ships. Calculations are carried out for ships produced between 2018 and 2020 with a capacity of more than 20,000 TEU. For these ships, the average power of the main system is calculated at around 64.00 kW. The study focuses on a propulsion engine system with features such as extraction control, bypass control, and either one or two turbines. The direct thermodynamic cycle of the VHTR offers high efficiency, smaller sizes, and flexible power control, thus eliminating the need for helium storage and enabling rapid power changes. In addition, this article highlights the advantages of bypass control of the turbine, which avoids the need to shut down the propulsion engine in the harbour. The findings suggest that nuclear propulsion could play a crucial role in the future of maritime technology.
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Thermosensitive composite based on agarose and chitosan saturated with carbon dioxide. Preliminary study of requirements for production of new CSAG bioink.
- Adrianna Banach-Kopeć
- Szymon Mania
- Robert Tylingo
- Agata Wawrzynowicz
- Monika Pawłowska
- Katarzyna Czerwiec
- Milena Deptuła
- Michał Pikuła
This study introduces a method for producing printable, thermosensitive bioink formulated from agarose (AG) and carbon dioxide-saturated chitosan (CS) hydrogels. The research identified medium molecular weight chitosan as optimal for bioink production, with a preferred chitosan hydrogel content of 40–60 %. Rheological analysis reveals the bioink's pseudoplastic behavior and a sol-gel phase transition between 27.0 and 31.5 °C. The MMW chitosan-based bioink showed also the most stable extrusion characteristic. The choice of chitosan for the production of bioink was also based on the assessment of the antimicrobial activity of the polymer as a function of its molecular weight and the degree of deacetylation, noting significant cell reduction rates for E. coli and S. aureus of 1.72 and 0.54 for optimal bioink composition, respectively. Cytotoxicity assessments via MTT and LDH tests confirm the bioink's safety for L929, HaCaT, and 46BR.1 N cell lines. Additionally, XTT proliferation assay proved the stimulating effect of the bioink on the proliferation of 46BR.1 N fibroblasts, comparable to that observed with Fetal Bovine Serum (FBS). FTIR spectroscopy confirms the bioink as a physical polymer blend. In conclusion, the CS/AG bioink demonstrates the promising potential for advanced spatial cell cultures in tissue engineering applications including skin regeneration.
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Three dimensional simulations of FRC beams and panels with explicit definition of fibres-concrete interaction
- Ireneusz Marzec
- Jan Suchorzewski
- Jerzy Bobiński
High performance concrete (HPC) is a quite novel material which has been rapidly developed in the last few decades. It exhibits superior mechanical properties and durability comparing to normal concrete. HPC can achieve also superior tensile performance if strong fibres (steel or carbon) are implemented in the matrix. Thus, there exist the unabated interest in studying how the addition of different types of fibres modifies the behaviour of HPC. Nowadays, a standard numerical approaches to model the behaviour of fibre reinforced concrete (FRC) are carried out by means of the smeared or discrete crack modelling of homogenous media with appropriately changed stress-strain relationships. The objective of this paper is to develop a new and efficient mesoscale modelling approach for steel fibre reinforced high-performance concrete. The main idea of presented approach is to assume the fully 3D modelling with taking into account explicitly the distribution and orientation of the steel fibres. As a benchmark, results obtained from experimental campaign on beams and panels made from high-performance concrete with steel fibres of different sizes and dosages were taken. Results of numerical simulations were directly compared with experimental outcomes in order to validate and calibrate FE-model and to introduce the efficient numerical modelling tool.
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Three modes of electrochemical impedance spectroscopy measurements performed on vanadium redox flow battery
- Joanna Krakowiak
- Wojciech Bącalski
- Grzegorz Lentka
- Pekka Peljo
- Paweł Ślepski
This article presents an innovative approach to monitor working redox flow batteries using dynamic electrochemical impedance spectroscopy, diverging from the commonly sequential impedance methods carried out under potentiostatic or galvanostatic conditions close to the open circle voltage. The authors introduce a fresh variation of dynamic impedance measurement that leverages an amplitude-modulated multi-frequency alternating current perturbation signal. This technique leads to a reduction in measurement time, making it possible to monitor impedance in real-time under typical operational conditions. Consequently, it effectively addresses the limitations stemming from the absence of stationary conditions during impedance measurements. There is no doubt that measurement techniques enabling the study of processes during the operational life of a battery provide the most valuable insights into the properties of these systems. The potential of this proposed approach is exemplified through the examination of a full vanadium redox flow battery as a case study. Classical impedance measurements were also conducted under potentiostatic and galvanostatic conditions with sequential frequency signal change, which requires stopping the battery operation, resulting in electrode potential changes of over 200 mV compared to the working system. Spectra for all modes of measurements were compared. In the case of dynamic measurements, such significant differences in spectra during charging and discharging are not observed, which is characteristic of classical measurements. The authors deliberately and consciously refrain from analyzing the results by fitting equivalent circuits.
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Three-component NiO/Fe3O4/rGO nanostructure as an electrode material towards supercapacitor and alcohol electrooxidation
- Mohammad Bagher Askari
- Mohammad Taghi Tourchi Moghadam
- Parisa Salarizadeh
A nanocomposite made of nickel oxide and iron oxide (NiO/Fe3O4) and its hybrid with reduced graphene oxide (rGO) as a conductive substrate with a highly functional surface (NiO/Fe3O4/rGO) was synthesized using a simple hydrothermal approach. This study addresses the challenge of developing efficient materials for energy storage and alcohol fuel cells. After confirming the synthesis through structural analysis, the potential of these nanocomposites as supercapacitor electrodes and catalysts for methanol and ethanol oxidation in alcohol fuel cells were evaluated. The synergy of combining the two metal oxides and adding rGO to the composite structure led to excellent electrocatalytic activity in alcohol oxidation. For the modified NiO/Fe3O4/rGO electrode in the methanol oxidation reaction (MOR), a current density of 450 mA/cm2 at 0.67 V and excellent catalyst stability of 98.7 % over 20 h in chronoamperometric analysis were observed. In the ethanol oxidation reaction (EOR), an oxidative current of 235 mA/cm2 at a peak potential of 0.76 V was seen, with catalyst stability of 96.4 % after 20 h. As a supercapacitor electrode, the NiO/Fe3O4 composite demonstrated a specific capacitance of 946 F/g, while NiO/Fe3O4/rGO showed 1155 F/g. The stability of these electrodes after 10000 GCD cycles was 83.6 % and 90.6 %, respectively. These findings suggest that the proposed structures are cost-effective and reliable alternatives for energy storage and production, suitable for alcohol fuel cells and supercapacitors.
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Three-dimensional characterization of porosity in iron ore pellets: A comprehensive study
- Pasquale Cavaliere
- Behzad Sadeghi
- Leandro Dijon
- Aleksandra Laska
- Damian Koszelow
This paper presents a comprehensive study on the production and reduction of high-quality iron ore pellets characterized by a basicity index nearing 0.5 and diameters ranging from 1 to 2 cm. The reduction process was carried out in a hydrogen atmosphere at temperatures spanning 800–1000 ◦ C and a pressure of 8 bar. Initial f indings revealed substantial variations in pellet density and compressive strength, attributed to their mean dimensions. To delve into the microstructural transformations occurring during reduction, meticulous microtomographic analyses were conducted on each pellet before and after the reduction process. The research assessed reducibility factors such as porosity, pore size, and tortuosity adjustments across diverse reduction conditions. The study highlights the intimate connection between the reduction process rate, processing parameters, and pellet microstructure. Furthermore, the metallization tendencies were explored through extensive reduction experiments involving multiple pellets. These findings offer crucial insights into optimizing iron ore pellet performance during production and reduction processes, contributing to advancements in industrial applications.
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Ti4Ir2O : A time reversal invariant fully gapped unconventional superconductor
- Debarchan Das
- KeYuan Ma
- Jan Jaroszynski
- Vahid Sazgari
- Tomasz Klimczuk
- Fabian O. von Rohr
- Zurab Guguchia
Here we report muon spin rotation (μSR) experiments on the temperature and field dependence of the effective magnetic penetration depth λ(T ) in the η-carbide-type suboxide Ti4Ir2O, a superconductor with a considerably high upper critical field. The temperature dependence of λ(T ), obtained from transverse-field (TF)-μSR measurements, is in perfect agreement with an isotropic fully gaped superconducting state. Furthermore, our ZF μSR results confirm that the time-reversal symmetry is preserved in the superconducting state. We find, however, a remarkably small ratio of Tc/λ −2 0 ∼ 1.22. This value is close to most unconventional superconductors, showing that a very small superfluid density is present in the superconducting state of Ti4Ir2O. The presented results will pave the way for further theoretical and experimental investigations to obtain a microscopic understanding of the origin of such a high upper critical field in an isotropic single-gap superconducting system.
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Timed rolling and rising tests in Duchenne muscular dystrophy ambulant boys: a feasibility study
- Agnieszka Sobierajska-Rek
- Joanna Jabłońska-Brudło
- Aneta Dąbrowska
- Wiktoria Wojnicz
- Jarosław Meyer-Szary
- Jolanta Wierzba
BACKGROUND: Functional activities are extensively used in motor assessments of patients with Duchenne muscular dystrophy. The role of timed items has been reported as an early prognostic factor for disease progression. However, there are two functional activities that are not widely assessed in clinical practice among Duchenne muscular dystrophy patients: rolling and bed rising. This study aimed to investigate whether the 360-degree roll (roll) and supine to sit-to-edge (bed rise) measurements are feasible tools reflecting the functional status of ambulatory DMD children by establishing possible correlations between validated measures: the Vignos Scale (VS), timed rise from floor and the 6-Minute Walk Test (6MWT). METHODS: A total of 32 ambulant boys with DMD were assessed using timed items, the 6MWT and VS. RESULTS: The roll and bed rise are correlated with each other. The 6MWT, the floor rise and VS are correlated with the roll and with the bed rise. CONCLUSIONS: Findings offer preliminary empirical evidence addressing feasibility and safety of roll and bed rise measurements. There is a potential clinical utility of these tests in assessing functional status of DMD ambulant patients.
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TiO2 and Reducing Gas: Intricate Relationships to Direct Reduction of Iron Oxide Pellets
- Pasquale Cavaliere
- Behzad Sadeghi
- Aleksandra Laska
- Damian Koszelow
In response to the imperative for sustainable iron production with reduced CO2 emissions, this study delves into the intricate role of TiO2 in the direct reduction of iron oxide pellets. The TiO2-dependent reducibility of iron oxide pellets utilizing H2 and CO gas across varied temperatures and gas compositions is thoroughly investigated. Our findings unveil the nuanced nature of the TiO2 effect, underscored by its concentration-dependent behavior, revealing an optimal range between 1 and 1.5 pct TiO2, where a neutral or positive impact on reduction kinetics and diffusion coefficient is observed. Notably, the synergistic interplay of CO and H2 at 1000 C emerges as particularly efficacious, suggesting complementary effects on the reduction process. The introduction of H2 into the reducing atmosphere regulated by CO not only extends the transition range but also markedly expedites the rate of reduction. Furthermore, our study highlights the temperature sensitivity of the TiO2 effect, with higher TiO2 content correlating with prolonged reduction time in a 100 pct H2 atmosphere at 900 C. In a 100 pct H2 atmosphere, the non-contributory role of TiO2 stems from the water-gas shift reaction. Conversely, introducing H2 into a CO-controlled reducing atmosphere with TiO2 enhances the transition range and expedites the reduction rate. Additionally, our findings underscore the role of total iron content, revealing a direct correlation with the reduction process.
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TiO2 nanotubes modification by photodeposition with noble metals: Characterization, optimization, photocatalytic activity, and by-products analysis
- João Lincho
- Paweł Mazierski
- Tomasz Klimczuk
- Rui F. Martins
- João Gomes
- Adriana Zaleska-Medynska
Self-organized TiO2 nanotubes (TNTs) with 4 µm length were obtained by anodization method and calcined to obtain anatase crystallite phase. The photocatalysts were further decorated with Au, Ag, Pt or Pd nanoparticles (NPs), varying the metal loads (0.50, 0.75, 1, 2 and 5 mol%) by photodeposition. The material characterization confirmed the presence of nanoparticles in the TNTs surface, signs of the localized surface plasmon resonance (LSPR) effect for some samples and a bandgap energy of 3.1–3.2 eV. Photoluminescence measurements also confirmed that most of the samples with metallic nanoparticles had the recombination of photogenerated carriers lowered due to the trapping effect of the deposited metal NPs. The photoactivity was evaluated by phenol degradation using UV-Vis or visible radiation. Under UV-Vis, the best samples (2 and 5 mol% of Au-TNTs and 0.75, 1, and 2 mol% of Pd-TNTs) led to 97% phenol removal in 60 min while pristine TNTs reached 92% removal. Under visible radiation, the pristine and the Au-TNTs led to about 3% removal, with the best sample being 2 mol% Pd-TNTs with 14% removal in 60 min. Similar results were obtained for 1 and 5 mol% Pd-TNTs (12% and 13% of phenol removal, respectively). The by-products analysis suggest different degradation mechanisms and it is observed different kinetic rates for different metal types, metal loads or types of radiation.
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Torsional earthquake-induced pounding between adjacent buildings founded on different soil types
- Mahmoud Miari
- Robert Jankowski
This paper investigates the effect of the soil type on the torsional response of build- ings experiencing torsional pounding due to earthquake excitations. Six buildings (one 4-storey building and five 6-storey buildings) with different configurations have been considered. First, pounding between different structures has been analysed for a specified soil type and the effect of the torsional pounding and the contact asymmetry on the torsional response of colliding buildings has been investigated. Then, these pounding cases have been considered for different soil types to study the effect of the soil type on the torsional response of buildings experiencing torsional pounding. Five soil types have been considered, i.e. hard rock, rock, very dense soil and soft rock, stiff soil and soft clay soil. The results of the study indicate that the earthquake-induced torsional pounding causes an increase in the peak storey rotation of the colliding buildings as compared to the symmetric pounding in all cases. Higher peak storey rotations have been experienced for colliding buildings founded on the soft clay soil, then for buildings founded on the stiff soil, then for buildings founded on very dense soil and soft rock, and finally for buildings founded on the rock and hard rock.
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Toward an understanding of occupational burnout among employees with autism – the Job Demands‑Resources theory perspective
- Michał Tomczak
- Konrad Kulikowski
This article aims to gain insight into the phenomenon of occupational burnout among employees with autism based on the theoretical framework of the Job Demands-Resources theory and the literature on employees with autism in the workplace. Firstly, we argue that although the resources and demands of the neurotypical and neurodivergent employees might be different, the theoretical mechanism of occupational burnout formation remains similar among the neurotypical and neurodivergent employees, leading to the similar burnout experience. Next, we distinguish key demands that might drain neurodiverse employees’ energy, and spark burnout, and propose a set of resources that might foster their achievement of work goals and mitigate demanding working conditions. We emphasise that the nature of job demands/resources that may cause burnout is not universal but might depend on how employees evaluate them, thus neurotypical and neurodiverse workers who evaluate the same work characteristics differently might complement each other, increasing organisational diversity without losing productivity. Our conceptual elaboration contributes to the theory and practice of healthier workplaces by providing tools and inspiration to managers, policymakers, and all stakeholders interested in creating a diverse and productive workplace. Moreover, our work might spark a much needed debate on occupational burnout among employees with autism and encourage conducting further empirical studies.
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Toward Human Chromosome Knowledge Engine
- Maiqi Wang
- Yi Lai
- Minghui Li
- Haoxi Zhang
- Edward Szczerbicki
Human chromosomes carry genetic information about our life. Chromosome classification is crucial for karyotype analysis. Existing chromosome classification methods do not take into account reasoning, such as: analyzing the relationship between variables, modeling uncertainty, and performing causal reasoning. In this paper, we introduce a knowledge engine for reasoning-based human chromosome classification that stores knowledge of chromosomes via a novel representation structure, the Chromosome Part Description (CPD), and reasons over CPDs by utilizing the probability tree model (PTM) for classification. Each CPD keeps information on a particular feature of chromosomes, while the PTM provides causal reasoning capability taking CPDs as nodes and dependencies between CPDs and types as edges. Experimental results show that the proposed knowledge engine’s performance increases when providing more CPDs and achieves 100% classification accuracy with more than three CPDs.
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Toward Sustainable Development: Exploring the Value and Benefits of Digital Twins
- Paweł Weichbroth
- Krystian Jandy
- Józef Żurada
The complexity and number of data streams generated by internal processes exceed the capabilities of most current simulation environments. Consequently, there is a need for the development of more advanced solutions that can handle any number of simultaneous simulations. One of the most promising ideas to address these and other challenges is the concept of a Digital Twin (DT), which refers to a digital representation or a virtual model designed to accurately reflect an intended or actual physical product, system, or process (i.e., a physical twin). As a Digital Twin spans the life-cycle of its physical twin, its development and application can bring considerable benefits to organizations seeking to improve existing processes as well as implement new ones. However, few studies have comprehensively examined the value and benefits of Digital Twins. To fill this gap, this study aims to provide a better understanding of this technology by reviewing the contemporary literature, with a particular focus on the documented case studies, as well as reported business and industrial deployments. The results obtained show that Digital Twins have proven beneficial for maintenance, cost reduction, optimization, simulation performance, monitoring, product life-cycle understanding, assessment validation, performance evaluation, product design, and safety and risk mitigation. In addition, when considering the human factor, DTs can facilitate education and training, team collaboration, and decision making. Undeniably, Digital Twins are a game changer for safer, faster, and more sustainable development.
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Towards a reliable method for extrapolation of propulsion performance for vessels with twin-crp-pod system
- Hanna Pruszko
- Maciej Reichel
- Marek Necel
- Sören Brüns
The study presents power performance prediction of an Ultra Large Container Ship (ULCS) with hybrid twin-crp-pod propulsion system. Twin crp-pod propulsion system is a combination of three concepts: twin screw, contra-rotating propellers (crp) and conventional shaft propellers with pod propulsors behind. The presented study shows the current extrapolation method for crp propulsion systems and tries to point out its weaknesses. As a case study, a 400 m ULCS has been investigated in full-scale and in model scales of 24 and 37.416. The analyses were carried out for all scales with use of CFD numerical methods and for the scale of 37.416 based on towing tank tests. All the results have been extrapolated with the same method and results have been compared. The investigations clearly show differences in delivered power prediction extrapolated from towing tank results giving the maximum value and from CFD made to scale of 24 the minimum value. Finally, conclusions on possible sources of differences, including the numerical and analytical methods are presented.
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Towards an analysis framework for operational risk coupling mode: A case from MASS navigating in restricted waters
- Cunlong Fan
- Jakub Montewka
- Victor Bolbot
- Yang Zhang
- Yuhui Qiu
- Shenping Hu
Maritime Autonomous Surface Ships (MASSs) constitute highly interconnected and tightly coupled multistate systems. Incorporating the coupling effects of both interactions and dependencies is centrally important to ensure navigation safety of MASSs. This paper proposes a framework for examining the coupling effects in the operational modes (OM) of MASSs. Failure Modes (FMs) of MASSs related to interactions with the environment and subsystems are identified using 24Model developed based on conventional ship accidents involving grounding in the west of Shenzhen port, China. FMs related to grounding are classified into the five risk types of human, organization, ship, environment, and technology, considering three OMs (states), i.e., manual control, remote control, and autonomous control. Based on this classification, the N-K model is applied to calculate the risk coupling values of scenarios involving multiple risk types. These scenarios are then ranked by the risk coupling values of the three OMs, and values are compared among different OMs. The results indicate that for grounding in the west of Shenzhen port most risk coupling values increase with increasing risk type diversity. Furthermore, the risk coupling mechanism in remote control differs significantly from that in manual control and autonomous control, thus risk management of MASS OMs should vary.
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Towards ecological transformation: developing architectural education and research through L’Art Urbain initiatives
- Izabela Burda
- Katarzyna Zielonko-Jung
- Louis Moutard
- Aude Vapard
- Anne Durand
The aim of this study was to examine the collaboration between the Faculty of Architecture at Gdańsk University of Technology (Gdańsk Tech), Poland and L’Art Urbain dans les Territoires, Paris, France, recognised for its involvement in transforming urban development over four decades. The focus is placed on the evolution of the association’s annual competition, highlighting the growing emphasis on sustainability. Special attention is dedicated to the integration of themes relating to environmental and social sustainability into the curriculum of Master’s level design courses. This study highlights the role of the competition in enhancing education in architecture and urban planning, as well as in developing research at Gdańsk Tech, especially in fields related to the social and environmental aspects of urban regeneration. Moreover, the research also considers the wider implications of this collaboration, in particular its effectiveness in linking theoretical education to real-world challenges and in equipping architects to deal with the complexities of sustainable urban development.
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Towards hand grip force assessment by using EMG estimators
- Robert Barański
- Wiktoria Wojnicz
- Bartłomiej Zagrodny
- Michał Ludwicki
- Agnieszka Sobierajska-Rek
The purpose of this study was to propose a method to assess individual regression (calibration) curves to establish a relationship between an isometric grip force and surface electromyography (EMG) estimator. In this study 18 healthy volunteers (12 male (23.0 ± 2.0 years) and 6 female (23.2 ± 0.7 years)) had been examined. Ten EMG estimators (mean absolute value, root mean square, entropy, energy, turns per second, mean of zero crossings, median power frequency, mean power frequency, and Hilbert transforms), two EMG locations (brachioradialis and flexor digitorum superficialis) and five types of regression curves (linear, exponential, power, logarithm, and quadratic polynomial) have been tested. Using a quadratic polynomial regression curve and energy EMG estimator of the flexor digitorum superficialis muscle, it was obtained the lowest dispersity of EMG estimator and the most accurate prediction of grip isometric force among all tested EMG estimators.
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Towards sustainable catalyst-free biomass-based polyurethane-wood composites (PU-WC): From valorization and liquefaction to future generation of biocomposites
- Adam Olszewski
- Paulina Kosmela
- Łukasz Piszczyk
A substantial aspect of materials engineering lies in the responsible process of designing polymer-based materials. Due to environmental pollution, excessive consumption of natural resources, and increasing environmental awareness of society, there is a massive need for polyurethane (PU) materials with reduced environmental impact. To date, research on catalyst-free polyurethane-wood composites (PU-WC) has demonstrated a huge potential for commercialization in industrial production and can be used as a replacement for commonly used wood-plastic composites and wood-based panels. Based on this research, the introduction of new greener alternatives for petrochemical polyols to develop PU-WCs with a high biomass share could be interesting. In this study, up to 80% of bio-based polyol (BP) synthesized via biomass liquefaction was introduced to the polymer matrix. The effect of petrochemical polyol substitution was examined by mechanical testing, scanning electron microscopy (SEM), water absorption tests, and thermal analysis. The conducted research revealed that the structure and properties of PU-WCs strongly depend on the share of BP. The most promising composites were manufactured with up to 40% BP. The flexural strength of the PU-WC decreases from 25 to 9 MPa, and the flexural modulus varies from 1780 to 800 MPa. This may be caused by deteriorated adhesion between composite phases and a reduction in the stiffness of the materials due to the decrease in crosslinking density, which was confirmed by the decrease in glass transition temperature from 96 to 26 °C. In summary, this work shows the next step towards cleaner production of PU-WCs by substituting petrochemical polyols for alternatives synthesized using renewable resources.
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Towards truly sustainable IoT systems: the SUPERIOT project
- Marcos Katz
- Tuomas Paso
- Konstantin Mikhaylov
- Luis Pessoa
- Helder Fontes
- Liisa Hakola
- Jaakko Leppäniemi
- Emanuel Carlos
- Guido Dolmans
- Julio Rufo
- Marcin Drzewiecki
- Hazem Sallouha
- Bruce Napier
- André Branquinho
- Kerstin Eder
This paper provides an overview of the SUPERIOT project, an EU SNS JU (Smart Networks and Services Joint Undertaking) initiative focused on developing truly sustainable IoT systems. The SUPERIOT concept is based on a unique holistic approach to sustainability, proactively developing sustainable solutions considering the design, implementation, usage and disposal/reuse stages. The concept exploits radio and optical technologies to provide dual-mode wireless connectivity and dual-mode energy harvesting as well as dual-mode IoT node positioning. The implementation of the IoT nodes or devices will maximize the use of sustainable printed electronics technologies, including printed components, conductive inks and substrates. The paper describes the SUPERIOT concept, covering the key technical approaches to be used, promising scenarios and applications, project goals and demonstrators which will be developed to the proof-of-concept stage. In addition, the paper briefly discusses some important visions on how this technology may be further developed in the future.