2021 - Repozytorium publikacji - Politechnika Gdańska

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Visible-light-driven lanthanide-organic-frameworks modified TiO2 photocatalysts utilizing up-conversion effect
- Patrycja Parnicka
- Wojciech Lisowski
- Tomasz Klimczuk
- Justyna Łuczak
- Andrzej Żak
- Adriana Zaleska-Medynska
2021 Pełny tekst APPLIED CATALYSIS B-ENVIRONMENTAL
Highly efficient and quite stable composite with core-shell-like architecture reported herein, responds to the challenge of sunlight-driven photocatalysts. The Ln(ndc)/TiO2 photocatalytic system comprises active lanthanide-carboxylate coordination networks (Nd, Er, Ho, and Tm as metal ions, and 2,6-naphthalene dicar-boxylic acid as the organic linker) and inert titanium dioxide and allow to convert incompatible visible radiation into functional ultraviolet photons. The combination of the antenna-reactor photocatalyst complex with Ln(ndc) shell layers promotes light harvesting and efficient mass transfer, resulting in additional photoexcited electrons. The Nd(ndc) metal-organic framework successfully activate TiO2 via up-conversion energy transfer. The apparent quantum efficiency, determined at wavelengths corresponding to the transitions from the Nd3+ground state, equals to 2.8% and 3.2% for 525 and 583 nm, respectively. Integration of the Nd(ndc) MOF and TiO2 results in the highest efficiency of phenol degradation, affording a value of 87.5% after 60 min of visible light (λ >420 nm) exposure.
Voice Multilateration System
- Robert Burczyk
- Krzysztof Cwalina
- Małgorzata Gajewska
- Jarosław Magiera
- Piotr Rajchowski
- Jarosław Sadowski
- Jacek Stefański
2021 Pełny tekst SENSORS
This paper presents an innovative method of locating airplanes, which uses only voice communication between an air traffic controller and the pilot of an aircraft. The proposed method is described in detail along with its practical implementation in the form of a technology demonstrator (proof of concept), included in the voice communication system (VCS). A complete analysis of the performance of the developed method is presented, including the results of simulation and measurement tests in real conditions. The obtained results are very optimistic and indicate that the proposed solution may constitute an alternative method of locating aircraft in emergency conditions, i.e., a backup solution in the case of failure of other positioning systems.
Voltage variations and their reduction in a rural low-voltage network with PV sources of energy
- Agata Szultka
- Seweryn Szultka
- Stanisław Czapp
- Ryszard Zajczyk
2021 Pełny tekst Electronics
Renewable sources of energy (RES), especially photovoltaic (PV) micro-sources, are very popular in many countries. This way of clean power production is applied on a wide scale in Poland as well. The Polish legal regulations and tariffs specify that every prosumer in a low-voltage network may feed this network with a power not higher than the maximum declared consumed power. In power networks with RES, the voltage level changes significantly along the power line and depends on the actually generated as well as consumed power by particular prosumers. There are cases that prosumers connected to this line cannot produce and inject the full permissible power from PV sources due to the level of a voltage higher than the technically acceptable value. In consequence, it leads to the lack of profitability of investments in installations with PV sources. In this paper, voltage variations in a real rural low-voltage network with PV micro-sources are described. The possible two general solutions of voltage levels improvement are discussed – increase in the cross-sectional area of the bare conductors in the existing overhead line as well as the replacement of the overhead line with a cable line. The recommended solution for the analyzed network, giving the best reduction of voltage variations and acceptable cost, is underlined. Such a recommendation can also be utilized in other rural networks.
Volumetric and torque efficiency of pumps during start-up in low ambient temperatures
- Ryszard Jasiński
2021
The volumetric, torque and total efficiency of hydraulic pumps change during start-up in low ambient temperatures, as well as in thermal shock conditions, un-til they reach the set conditions. The time to reach steady-state conditions de-pends on many parameters: ambient temperature, flow rate, fluid temperature, design of hydraulic units. The author carried out tests of hydraulic pumps in the Hydraulics Laboratory of the Faculty of Mechanical Engineering of the Gdańsk University of Technology. In the research four types of pumps were investigated: several gear pumps, two axial piston pumps of different designs and one radial piston pump. It was proved, that in thermal shock conditions some malfunctions may occur, espe-cially with large temperature difference between oil and pump. Experimental research of various hydraulic pumps operating in low ambient temperatures, undertaken by the author, allows to answer the question how the volumetric and torque efficiency changes in such conditions and what parame-ters does it depend on.
Warstwa odcinająca z geotekstyliów w nawierzchniach drogowych. Wymagania i zasady doboru właściwości
- Jacek Alenowicz
2021 Pełny tekst Magazyn Autostrady
W artykule omówiono zagadnienia związane ze stosowaniem geotekstyliów jako warstwy odcinającej w budowie nawierzchni drogowych. Podano wymagania ogólne, jakie stawia się geotekstylion w omawianym zastosowaniu. Przedstawiono klasyfikacje wykorzystywane w wybranych krajach oraz wymagania stosowane w Polsce. Zwrócono uwagę na czynniki wpływające na prawidłowy wybór geotekstyliów do wykonania warstwy odcinającej
Waste materials assessment for phosphorus adsorption toward sustainable application in circular economy
- Magda Kasprzyk
- Krzysztof Czerwionka
- Magdalena Gajewska
2021 Pełny tekst RESOURCES CONSERVATION AND RECYCLING
Phosphorus is the main determinant of nutrient enrichment in the water bodies. Many resources including nutrients may be shortly exhausted, assuming current consumption. This scenario leads to growing interest in resources recovery and/or reuse, which together with sustainable energy consumption and waste reduction are the main courses of the circular economy. Usage of coagulants in wastewater treatment plants (WWTP) does not allow phosphorus to be recovered from the sludge. An alternative method with recovery potential is the application of adsorbents. Many adsorbents have been approved for P-removal, however some of them are expensive. Response to that issue may be the application of waste materials and byproducts often intended for disposal/utilization. The main objective was to assess the P-removal efficiency of the waste materials/byproducts for application in small WWTP and eco-technologies like treatment wetlands as replacement of commercial adsorbents and alternative for conventional (chemical) treatment for potential phosphorus recovery. The materials investigated were (1) an expensive man-made product, (2) a byproduct with a high content of calcium oxide, and (3) drinking water treatment residuals (DWTRs) as beds from filters used to remove iron. Research was conducted in non-flow condition with various initial concentrations. The highest efficiency was received for fine-grained byproduct (9.58 mg/g), for commercial adsorbent LMB - 9.11 mg/g. The DWTRs adsorption was oscillated around 4.5 mg/g. These results confirmed the possibility of applying waste materials and byproducts for P-removal according to the circular economy idea. Further research should include implications of waste materials application to determine P-recovery concept.
Wastes from Agricultural Silage Film Recycling Line as a Potential Polymer Materials
- Jerzy Korol
- Aleksander Hejna
- Klaudiusz Wypiór
- Krzysztof Mijalski
- Ewelina Chmielnicka
2021 Pełny tekst Polymers
The recycling of plastics is currently one of the most significant industrial challenges. Due to the enormous amounts of plastic wastes generated by various industry branches, it is essential to look for potential methods for their utilization. In the presented work, we investigated the recycling potential of wastes originated from the agricultural films recycling line. Their structure and properties were analyzed, and they were modified with 2.5 wt % of commercially available compatibilizers. The mechanical and thermal performance of modified wastes were evaluated by tensile tests, thermogravimetric analysis, and differential scanning calorimetry. It was found that incorporation of such a small amount of modifiers may overcome the drawbacks caused by the presence of impurities. The incorporation of maleic anhydride-grafted compounds enhanced the tensile strength of wastes by 13–25%. The use of more ductile compatibilizers—ethylene-vinyl acetate and paraffin increased the elongation at break by 55–64%. The presence of compatibilizers also reduced the stiffness of materials resulting from the presence of solid particles. It was particularly emphasized for styrene-ethylene-butadiene-styrene and ethylene-vinyl acetate copolymers, which caused up to a 20% drop of Young’s modulus. Such effects may facilitate the further applications of analyzed wastes, e.g., in polymer film production. Thermal performance was only slightly affected by compatibilization. It caused a slight reduction in polyethylene melting temperatures (up to 2.8 °C) and crystallinity degree (up to 16%). For more contaminated materials, the addition of compatibilizers caused a minor reduction in the decomposition onset (up to 6 °C). At the same time, for the waste after three washing cycles, thermal stability was improved. Moreover, depending on the desired properties and application, materials do not have to go through the whole recycling line, simplifying the process, reducing energy and water consumption. The presented results indicate that it is possible to efficiently use the materials, which do not have to undergo the whole recycling process. Despite the presence of impurities, they could be applied in the manufacturing of products which do not require exceptional mechanical performance.
Water Behavior Near the Lipid Bilayer
- Natalia Kruszewska
- Krzysztof Domino
- Piotr Weber
2021
In this chapter, we focus on the dynamics of water molecules situated in the vicinity of a phospholipid bilayer. Using a molecular dynamics simulation method, we studied interactions between water and the bilayer and tracked trajectories of the water molecules. Based on the hypothesis that molecules trapped inside the bilayer make different motions than the ones which are either attached to the surface or move freely in the water bulk, we divided the water molecules into three groups – the ones that exhibited subdiffusion (confined) motion, the ones that move diffusionally in the bulk and the ones that move superdiffusively due to interactions with the moving bilayer. In detail, the water behavior near the bilayer has been analyzed by mean squared displacement and entropy computed separately for the above mentioned three groups of molecules. To explain the subdiffusion motion of the water molecules, the number and the duration of hydrogen bonds created between water molecules and the bilayer have been investigated. In addition, we examined the mechanism of water molecule self-diffusion, by means of statistical tests. Our studies aim to present insight into the understanding of the lipid’s role in water self-diffusion, which can be responsible for triggering different tribological responses of the system.
Water-lubricated stern tube bearing - experimental and theoretical investigations of thermal effects
- Michał Wodtke
- Wojciech Litwin
2021 Pełny tekst TRIBOLOGY INTERNATIONAL
The paper presents research results of thermal phenomena accompanying operation of a water-lubricated stern tube bearing with axial grooves. Experimental tests revealed, that intensity of forced axial flow has strong influence on bush temperature. Numerical simulations focused on investigation of the thermal phenomena under operation of water-lubricated journal bearing showed, that restricted axial flow promotes backflow of the water from bearing’s side zones through the grooves. The backflow temperature is higher than the supply temperature since under the conditions of restricted forced axial flow, it is impacted mainly by the temperature of the water outflow from the gap, which is higher due to the shearing of lubricating film. This effect causes rise in the temperature of the bearing bush.
W-dominance: Tradeoff-inspired dominance relation for preference-based evolutionary multi-objective optimization
- Rafał Szłapczyński
- Joanna Szłapczyńska
2021 Pełny tekst Swarm and Evolutionary Computation
The paper presents a method of incorporating decision maker preferences into multi-objective meta-heuristics. It is based on tradeoffcoefficients and extends their applicability from bi-objective to multi-objective. The method assumes that a decision maker specifies a priori each objective’s importance as a weight interval. Based on this, w-dominance relation is introduced, which extends Pareto dominance. By replacing reference points with weight intervals the method eliminates the need for any knowledge concerning expected solutions. Instead, decision maker reflects his context-independent policy regarding objectives. The proposed w-dominance was incorpo- rated into selected multi-objective metaheuristics. Following this, three new metrics were designed. The metrics include prescreening true Pareto Front and final population according to w-dominance relation. Based on pre- liminary tests, Vector Angle Evolutionary Algorithm (VaEA) was selected as the best match for w-dominance. W-dominance-extended VAEA (wVAEA) was compared in a series of simulations with four state-of-the-art refer- ence point-based multi-objective algorithms. The results show that wVaEA outperforms the four representative algorithms for selected benchmark problems.
Weakly-Supervised Word-Level Pronunciation Error Detection in Non-Native English Speech
- Daniel Korzekwa
- Jaime Lorenzo-trueba
- Thomas Drugman
- Shira Calamaro
- Bożena Kostek
2021 Pełny tekst
We propose a weakly-supervised model for word-level mispronunciation detection in non-native (L2) English speech. To train this model, phonetically transcribed L2 speech is not required and we only need to mark mispronounced words. The lack of phonetic transcriptions for L2 speech means that the model has to learn only from a weak signal of word-level mispronunciations. Because of that and due to the limited amount of mispronounced L2 speech, the model is more likely to overfit. To limit this risk, we train it in a multi-task setup. In the first task, we estimate the probabilities of word-level mispronunciation. For the second task, we use a phoneme recognizer trained on phonetically transcribed L1 speech that is easily accessible and can be automatically annotated. Compared to state-of-the-art approaches, we improve the accuracy of detecting word-level pronunciation errors in AUC metric by 30% on the GUT Isle Corpus of L2 Polish speakers, and by 21.5% on the Isle Corpus of L2 German and Italian speakers
Weldability of Underwater Wet-Welded HSLA Steel: Effects of Electrode Hydrophobic Coatings
- Jacek Tomków
2021 Pełny tekst Materials
The paper presents the effects of waterproof coatings use to cover electrodes on the weldability of high-strength, low-alloy (HSLA) steel in water. With the aim of improving the weldability of S460N HSLA steel in water, modifications of welding filler material were chosen. The surfaces of electrodes were covered by different hydrophobic substances. The aim of the controlled thermal severity (CTS) test was to check the influence of these substances on the HSLA steel weldability in the wet welding conditions. The visual test, metallographic tests, and hardness Vickers HV10 measurements were performed during investigations. The results proved that hydrophobic coatings can reduce the hardness of welded joints in the heat-affected zone by 40–50 HV10. Additionally, the number of cold cracks can be significantly reduced by application of waterproof coatings on the filler material. The obtained results showed that electrode hydrophobic coatings can be used to improve the weldability of HSLA steel in underwater conditions.
What do hashtags afford in digital fashion communication? An exploratory study on Gucci-related hashtags on Twitter and Instagram.
- Olga Karamalak
- Nadzeya Kalbaska
- Lorenzo Cantoni
2021 Semiotica : Journal of the International Association for Semiotic Studies
Being enmeshed in a digital environment, we daily produce internet-mediated texts – encompassing several different semiotic codes – accessible on a global scale. Posts on different networks usually contain hashtags, which can be understood as affordances or behavior opportunities. These affordances allow specific actions both from the part of the writer and the reader. They can also be “behavior triggers,” which invite certain behavior online (e.g., to like, share, comment) or offline (e.g., to buy items of a specific brand). Digital fashion communication experts should take into consideration these affordances to pursue their goals in the activities related to marketing, promoting, creating engagement and communicating either about a brand or a brand item. While there is general research on reasons to hashtag and on the functions they perform, there is a gap in what hashtags “mean” and “do” in the fashion domain. The objectives of this paper are threefold: 1) to give an overview of the history of hashtags; 2) to present the affordances of hashtags, while creating a general table of affordances from the addresser’s perspective, based on the literature overview; 3) to perform a qualitative analysis of hashtags on Gucci official Twitter and Instagram accounts during a given time span and on other Gucci-related hashtags posted by common users. The choice of the brand is due to Gucci’s focus on active digital communication practices. Results can be valuable for both researchers and industry professionals involved in digital fashion communication.
What matters most to patients? On the Core Determinants of Patient Experience from Free Text Feedback
- Adegboyega Ojo
- Nina Rizun
2021 Pełny tekst
Free-text feedback from patients is increasingly used for improving the quality of healthcare services and systems. A major reason for the growing interest in harnessing free-text feedback is the belief that it provides richer information about what patients want and care about. The use of computational approaches such as structural topic modelling for analysing large unstructured textual data such as free-text feedback from patients has also been gain traction lately. However, its use for generating insights is constrained by the apparent lack of statistical rigour and explanatory capability required for credible evidence in decision making. From the theoretical perspective, theory-building from unstructured textual data is also currently problematic in IS and health service research. This study presents an approach to address this challenge by integrating text analytics, predictive and quantitative models as part of a computational grounded theory approach to determine factors that significantly determine overall patient experience.
Where Did Knowledge Management Go?: A Comprehensive Survey
- Rodrigo Oliveira de Castro
- Cesar Sanin
- Edward Szczerbicki
- Andrew Levula
2021 Pełny tekst CYBERNETICS AND SYSTEMS
Knowledge Management (KM) research outputs have been expanding exponentially in the past years, generating diversified topics, which lack integration and classification. It has been challenging for experts to classify KM because of its versatile open fields, and in our view, it contributes to the technocratic approach remaining behind the organizational approach. This paper highlights a way to classify KM publications through a pattern that will support technocratic developments representing knowledge in a more explicit form. This study uses a classification method thatuses a template in a taxonomy shape, executing some procedures and allowingan accurate identification and organizationof KM research outputs. The proposed taxonomy method is proven on a set of 150 different KM publications from the last 15 years. This scheme is grouped into two main categories: Conceptual and Empirical which could enable academics and practitioners alike to better understand the current gaps that are prevalent in KM.
Wideband Modeling of DC-DC Buck Converter with GaN Transistors
- Piotr Musznicki
- Pawel B. Derkacz
- Piotr Chrzan
2021 Pełny tekst ENERGIES
The general wideband modeling method of the power converter is presented on the example of DC-DC buck converter with GaN High Electron Mobility Transistors (HEMT). The models of all basic and parasitic components are briefly described. The two methods of Printed Circuit Board (PCB) layout parameter extraction are presented. The results of simulation in Saber@Sketch simulation software and measurements are compared. Next, the model of the converter is reduced to obtain one lumped inductance of the input filter PCB for the analytical prediction of transistor turn-off ringing frequency and overvoltage. The practical use of the model is presented for sizing optimal capacitance of snubber.
Wind Conditions at Pedestrian Level in Different Types of Residential Urban Development for a High Degree of Land Use Efficiency
- Katarzyna Zielonko-Jung
- Marta Poćwierz
- Robert Idem
2021 Pełny tekst Sustainability
The paper concerns wind conditions around urban building development at the pedestrian level. The article aims to identify aerodynamic phenomena around three types of multi-family housing developmentswith different forms and the same urban parameters of building development intensity (high intensity was taken into account). The aim of the research was mainly to achieve qualitative results that would lead to understanding fundamental processes and phenomena. Experimental studies in the wind tunnel were conductedon physical models at a scale of 1: 400 using visualization and erosion methods. These experiments yielded data regarding the arrangement of airflow directions and changes in airflow velocity, expressed as the amplification coefficient (α), the occurrence of which was caused by the presence of buildings. An analysis was conducted concerning wind conditions that constitute pedestrian comfort and influence the possibility for ventilation of spaces between buildings for the three selected models. The research results were compared, and an attempt was made to assess the most beneficial and the least favorable building development typesseem in this respect.
Wisdom from Experience Paradox: Organizational Learning, Mistakes, Hierarchy and Maturity Issues
- Wioleta Kucharska
2021 Pełny tekst Electronic Journal of Knowledge Management
Organizations often perceive mistakes as negligence and low-performance indicators, yet they can be a precious learning resource. However, organizations cannot learn from mistakes if they have not accepted them. This study aimed to explore how organizational hierarchy and maturity levels influence the relationship between mistakes acceptance and the ability to change. A sample composed of 380 Polish employees working in knowledge-driven organizations across various industries examined this phenomenon. Data collection occurred from November to December 2019. Data were analyzed through OLS regression, using PROCESS software. The findings revealed that the acceptance of mistakes positively influences adaptability to change. Moreover, because of mistakes acceptance, knowledge workers in organizations with a low-level hierarchy adapt to changes more effectively than those who work in strongly (or high-level) hierarchical companies. Additionally, higher hierarchy levels result in lower adaptability to change, which is particularly visible in mature organizations. The study's essence is the empirical proof that a high level of organizational maturity and hierarchy can block the adaptability to change if the organization stays on the single-loop of learning (does perfectly what it used to do). Mistakes acceptance and thanks to this, also learning from mistakes, support organizational change adaptability. Change adaptability is vital for double-loop learning (organizational actions re-framing). Moreover, this study has exposed the paradox of ‘wisdom from experience’ empirically. Namely, it is expected that experience and maturity result in positive outcomes and increased organizational leverage. Whereas more prominent, experienced, and mature organizations face serious difficulties when changing their routines and behaviors.
Within- and between-person factor structure of the Oldenburg Burnout Inventory: Analysis of a diary study using multilevel confirmatory factor analysis
- Ewa Gruszczynska
- Beata Basińska
- Wilmar B. Schaufeli
2021 Pełny tekst PLOS ONE
The study examined the factor structure of burnout, as measured with the Oldenburg Burnout Inventory. The participants were 235 employees of a public administration agency who assessed their burnout online for 10 consecutive working days. Two models were tested with multilevel confirmatory factor analysis, assuming the same one or two-factor structure at the within- and between-person levels. Both models showed a reasonable fit to the data, but due to a strong correlation between exhaustion and disengagement and low within-person reliability for disengagement, a unidimensional model seems more valid. A cross-level invariance was not confirmed for either of the structures, showing that factor loadings for the same items differ significantly between the levels. This suggests that burnout is not the same latent variable at each level; rather, there are factors other than daily burnout that influence person-level scores and ignoring these across-level discrepancies may lead to biased conclusions.
Wizualizacja opływu kształtu geometrycznego
- Andrzej Mrowiec
- Piotr Nowaczyk
- Anna Golijanek-Jędrzejczyk
2021
Zaprezentowane wyniki badań numerycznych środowisku ANSYS Fluent oraz wyniki badań eksperymentalnych pozwalają jednoznacznie stwierdzić, że przedstawione stanowisko laboratoryjne umożliwia obserwację dużego obszaru kanału wizualizacyjnego oraz charakter przepływu strumienia cieczy opływającego, którego rodzaju przeszkody.