2021 - Publications Repository - Gdańsk University of Technology

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Publications from the year 2021

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Thermoplastic starch nanocomposites using cellulose-rich Chrysopogon zizanioides nanofibers
- Midhun Dominic C.D.
- Derval dos Santos Rosa
- Paulo Henrique Camani
- Athira S Kumar
- Neenu K.v.
- P.M. Sabura Begum
- Divya Dinakaran
- Effina John
- Donna Baby
- Meenu Mariya Thomas
- Jaison M. Joy
- Jyotishkumar Parameswaranpillai
- Mohammad Saeb
2021 INTERNATIONAL JOURNAL OF BIOLOGICAL MACROMOLECULES
Green thermoplastic starch (TPS) nanocomposite films aided by cellulose nanofibers (CNFs) from Chrysopogon zizanioides roots were developed and characterized. When compared to other lignocellulosic fibers, Chrysopogon zizanioides roots revealed exceptionally high cellulose content (~48%). CNFs were separated using an environmentally friendly acid isolation technique that included three stages: (i) alkali treatment; (ii) bleaching; and (iii) mild acid hydrolysis using oxalic acid in an autoclave. Following that, green nanocomposite films were made from potato starch using the solution casting process, by which we used glycerol (30 wt%) to make thermoplastic starch. Then, cellulose nanofibers in different concentrations (0, 1, 2, 3, 4 wt%) were added to the thermoplastic starch matrix. The isolated CNFs had diameters in the range of 17–27 nm. Besides, these nanostructures presented a very high crystallinity index (~65%), thereby enhanced the thermal stability. TPS/CNF green nanocomposites containing 3 wt% CNFs had exceptional tensile strength (~161%), tensile modulus (~167%), thermal stability, and crystallinity. As a result, nanocomposite films made of starch and cellulose nanofibers (3 wt%) extracted from Chrysopogon zizanioides roots would be alternatives for sustainable packaging. It can be concluded that Chrysopogon zizanioides roots have high potential for polymer industry.
Three Principles for Healthy Living with Light and Lighting
- Karolina Zielińska-Dąbkowska
- Ruth Kelly Waskett
2021 Full text ARC Lighting In Architecture
The lockdown measures applied to cities and towns during the worldwide Covid-19 pandemic have had a widespread impact on people’s lives. Some have found themselves confined to their homes, with limited social contact and a reduced quality of life. Others have found that the lockdown improved their wellbeing, as more time was spent outside, instead of commuting and working in an office building, plus the benefits of spending increased quality time with loved ones. The pandemic raised public consciousness about the need to take control of our own wellbeing and health: in particular, to take greater care of immunity. There was also concern about the consequences of extended time spent in indoor spaces, which can create mental fatigue that can manifest itself in a number of ways, including reduced productivity, lack of concentration and in some cases, depression. Many people soon realised the simple things in life that had previously been taken for granted, such as access to daylight and contact with nature, play a vital role in mental health and wellbeing.
Three-dimensional modeling and automatic analysis of the human nasal cavity and paranasal sinuses using the computational fluid dynamics method
- Dmitry Tretiakow
- Krzysztof Tesch
- Jarosław Meyer-Szary
- Karolina Markiet
- Andrzej Skorek
2021 Full text EUROPEAN ARCHIVES OF OTO-RHINO-LARYNGOLOGY
Purpose The goal of this study was to develop a complete workflow allowing for conducting computational fluid dynam- ics (CFD) simulation of airflow through the upper airways based on computed tomography (CT) and cone-beam computed tomography (CBCT) studies of individual adult patients. Methods This study is based on CT images of 16 patients. Image processing and model generation of the human nasal cavity and paranasal sinuses were performed using open-source and freeware software. 3-D Slicer was used primarily for segmentation and new surface model generation. Further processing was done using Autodesk ® Meshmixer TM. The gov- erning equations are discretized by means of the finite volume method. Subsequently, the corresponding algebraic equation systems were solved by OpenFOAM software. Results We described the protocol for the preparation of a 3-D model of the nasal cavity and paranasal sinuses and high- lighted several problems that the future researcher may encounter. The CFD results were presented based on examples of 3-D models of the patient 1 (norm) and patient 2 (pathological changes). Conclusion The short training time for new user without a prior experience in image segmentation and 3-D mesh editing is an important advantage of this type of research. Both CBCT and CT are useful for model building. However, CBCT may have limitations. The Q criterion in CFD illustrates the considerable complication of the nasal flow and allows for direct evaluation and quantitative comparison of various flows and can be used for the assessment of nasal airflow.
Three-Dimensional Printing of Bone Models
- Angela Andrzejewska
2021
The trabecular bone occurs, for example, in the femoral heads. Understanding the phenomenon of bone tissue degeneration can be the basis for the possibility of looking for alternative methods of surgical treatment of bone loss. The paper presents the results of the trabecular bone model, which was produced in additive manufacturing method with fused filament fabrication technology. The verification of the mechanical behavior of the trabecular bone model was based on the analysis of uniaxial compression test. The model was also conditioned under degradation process to determine the influence of the physiological fluid environment due to changes in the mechanical response of the modeled bone. The obtained results showed that the mechanical strength of the proposed spongy bone model and the method of its production allow to obtain strength values close to the natural spongy bone. In addition, the strength did not change during the 4-week degradation process.
THREE-LEVEL F-TYPE INVERTER
- Charles Odeh
- Arkadiusz Lewicki
- Marcin Morawiec
- Dmytro Kondratenko
2021 IEEE TRANSACTIONS ON POWER ELECTRONICS
Given the recent available IGBT switch modules up to 6.5 kV, 1200 A rating, the prospect of the diode-free variant topology of the three-level neutral-point-clamped (3-level, T-type) inverter in certain medium voltage applications is bright; due to its small part count and low conduction losses compared to the diode-clamped NPC inverter. However, within this voltage range, the input dc voltage rating of 50% of the switches per inverter phase-leg still poses limitations to the deployment of 3-level T-type inverter. In view of these limitations, a reconfigured four-switch per phase-leg power circuit for 3-level inverter (F-type) is presented in this paper. The common node of the bidirectional switch in T-type inverter is explored to have only one power switch rated at input dc voltage and 3 switches rated at half the input dc voltage, per inverter-leg. This reduced voltage stress has inverter cost and loss implications. The performances and competitiveness of the three-level, F-type inverter are analyzed in detail and demonstrated with a hardware prototype. Results reveal that it has the potentials of being considered a real alternative to 3-level, T-type inverters for certain low- and medium-voltage applications.
Time-current tripping characteristics of RCDs for sinusoidal testing current
- Stanisław Czapp
2021
Low-voltage electrical installations are verified initially – before being put into operation, as well as periodically – during their utilization. According to the IEC standards, the scope of the verification includes measurements of both the tripping current and the disconnection time of residual current devices (RCDs). Experiences in RCDs testing show that disconnection times of two or more similar RCDs can be quite different. Significant differences in disconnection times are also noticed for the same RCD in the consecutive trials. This paper presents the result of the test of twenty-four RCDs. Their real tripping current, as well as disconnection time, have been verified. Differences in the obtained values of disconnection times are commented, and their possible sources are indicated.
Tin Oxide Encapsulated into Pyrolyzed Chitosan as a Negative Electrode for Lithium Ion Batteries
- Andrzej Nowak
- Maria Gazda
- Marcin Łapiński
- Zuzanna Zarach
- Konrad Trzciński
- Mariusz Szkoda
- Szymon Mania
- Jinjin Li
- Robert Tylingo
2021 Full text Materials
Tin oxide is one of the most promising electrode materials as a negative electrode for lithium-ion batteries due to its higher theoretical specific capacity than graphite. However, it suffers lack of stability due to volume changes and low electrical conductivity while cycling. To overcome these issues, a new composite consisting of SnO2 and carbonaceous matrix was fabricated. Naturally abundant and renewable chitosan was chosen as a carbon source. The electrode material exhibiting 467 mAh g−1 at the current density of 18 mA g−1 and a capacity fade of only 2% after 70 cycles is a potential candidate for graphite replacement. Such good electrochemical performance is due to strong interaction between amine groups from chitosan and surface hydroxyl groups of SnO2 at the preparation stage. However, the charge storage is mainly contributed by a diffusion-controlled process showing that the best results might be obtained for low current rates
To i-vote or not to i-vote: Drivers and barriers to the implementation of internet voting
- Nathan Licht
- David Duenas Cid
- Iuliia Krivonosova
- Robert Krimmer
2021 Full text
This paper investigates the drivers and barriers of internet voting and the implications of a global pandemic for the development of the respective technology. In contrast to the expected uptake in the early 2000s of internet voting, the technology is still rather seldomly used in election systems around the world. The paper at hand explores the different forces that drive or impede internet voting adoption from a political, social, legal, organizational, contextual, economic and technological perspective. In an exploratory approach, 18 expert interviews and extensive complementary desk research were conducted. The findings identified 15 general drivers and 15 general barriers for the process of internet voting adoption. The evidence suggests that for a large part, the political features, trust and perception are the most pivotal factors to internet voting development.
Topological, nonreciprocal, and multiresonant slow light beyond the time-bandwidth limit
- Kosmas L. Tsakmakidis
- Konstantinos Baskourelos
- Tomasz Stefański
2021 Full text APPLIED PHYSICS LETTERS
Topologically protected transport has recently emerged as an effective means to address a recurring problem hampering the field of slow light for the past two decades: its keen sensitivity to disorders and structural imperfections. With it, there has been renewed interest in efforts to overcome the delay-time-bandwidth limitation usually characterizing slow-light devices, on occasion thought to be a fundamental limit. What exactly is this limit, and what does it imply? Can it be overcome? If yes, how could topological slow light help, and in what systems? What applications might be expected by overcoming the limit? Our Perspective here attempts addressing these and other related questions while pointing to important new functionalities both for classical and quantum devices that overcoming the limit can enable.
Torque capacity of multidisc wet clutch with reference to friction occurrence on its spline connections
- Marcin Bąk
2021 Full text Scientific Reports
In this article developed mathematical model that includes friction occurrence on spline connections is presented. The work also contains results of experimental research on torque capacity of multidisc wet clutch. These results are expressed as a function of contact pressure for different number of friction surfaces. Due to increased interest in research concerning multidisc wet clutches it is essential to determine impact of friction on fit connections on transmitted torque. Analytical calculations that include both known loss coefficient and assumed lack of friction on fit connections are compared to results of experiments. The paper contains detailed description of test stand and methodology of experiment. As a result of conducted tests it was found that correction coefficients known from literature are highly inaccurate. Measured values of torque indicate that transmitted torque reach significantly higher values. It was also revealed that after slippage appeared, the pressure plate usually moved in the direction of exerted clamping force, but movement in reversed direction also took place for some experiments. While movement corresponding to clamping force reached ca. 0.08 mm, in opposite direction amounted to 0.02 mm. Furthermore, studies presented that lapping of adjacent friction surfaces greatly affects differences between respective results obtained for a specific experiment.
Torque Transmitted by Multi-plate Wet Clutches in Relation to Number of Friction Plates and Their Dimensions
- Marcin Bąk
- Piotr Patrosz
- Paweł Śliwiński
2021
In the paper results of experimental tests on multi-plate wet clutch torque capacity for various diameters and numbers of friction plates are presented. Construction of an apparatus for laboratory tests of wet clutch engagement, drag torque and maximum torque is shown. Methodology of maximum torque capacity experiment and hydraulic circuit diagram, which supplies a motor and an actuator for the experiment are described. Analytically calculated values of torque capacity are compared to results obtained with laboratory tests. Additionally, the article includes FEM analysis, that was used to obtain pressure distribution on every friction surface in relation to force applied to the assembly and to determine differences in these distributions. The analysis has helped to determine a mean radius of sliding interface on each surface and to compare their values to other plates and to result calculated analytically. A diagram is shown in the article, that demonstrates pressure concentration as a function of number of friction surfaces.
Total chromatic sum for trees
- Michał Małafiejski
- Krzysztof Ocetkiewicz
- Ewa Kubicka
- Grzegorz Kubicki
2021
The total chromatic sum of a graph is the minimum sum of colors (natural numbers) taken over all proper colorings of vertices and edges of a graph. We provide infinite families of trees for which the minimum number of colors to achieve the total chromatic sum is equal to the total chromatic number. We construct infinite families of trees for which these numbers are not equal, disproving the conjecture from 2012.
Total Completion Time Minimization for Scheduling with Incompatibility Cliques
- Klaus Jansen
- Alexandra Lassota
- Marten Maack
- Tytus Pikies
2021
This paper considers parallel machine scheduling with incompatibilities between jobs. The jobs form a graph equivalent to a collection of disjoint cliques. No two jobs in a clique are allowed to be assigned to the same machine. Scheduling with incompatibilities between jobs represents a well-established line of research in scheduling theory and the case of disjoint cliques has received increasing attention in recent years. While the research up to this point has been focused on the makespan objective, we broaden the scope and study the classical total completion time criterion. In the setting without incompatibilities, this objective is well-known to admit polynomial time algorithms even for unrelated machines via matching techniques. We show that the introduction of incompatibility cliques results in a richer, more interesting picture. We prove that scheduling on identical machines remains solvable in polynomial time, while scheduling on unrelated machines becomes APX-hard. Next, we study the problem under the paradigm of fixed-parameter tractable algorithms (FPT). In particular, we consider a problem variant with assignment restrictions for the cliques rather than the jobs. We prove that, despite still being APX-hard, it can be solved in FPT time with respect to the number of cliques. Moreover, we show that the problem on unrelated machines can be solved in FPT time for reasonable parameters, in particular, the parameter combination: maximum processing time, number of job kinds, and number of machines or maximum processing time, number of job kinds, and number of cliques. The latter results are extensions of known results for the case without incompatibilities, and can even be further extended to the case of total weighted completion time. All of the FPT results make use of n-fold Integer Programs that recently received great attention by proving their usefulness for scheduling problems.
Toward Intelligent Recommendations Using the Neural Knowledge DNA
- Guangjian Ning
- Chunwang Wu
- Haoxi Zhang
- Edward Szczerbicki
2021 Full text CYBERNETICS AND SYSTEMS
In this paper we propose a novel recommendation approach using past news click data and the Neural Knowledge DNA (NK-DNA). The Neural Knowledge DNA is a novel knowledge representation method designed to support discovering, storing, reusing, improving, and sharing knowledge among machines and computing systems. We examine our approach for news recommendation tasks on the MIND benchmark dataset. By taking advantages of NK-DNA, deep learning, and the SOEKS technologies, our approach can learn from users’ past behaviors to form reading preference of the user, and reuse learned knowledge for improving the recommendation performance.
Towards a classification of networks with asymmetric inputs
- Manuela Aguiar
- Ana Dias
- Pedro Da Costa Soares
2021 Full text NONLINEARITY
Coupled cell systems associated with a coupled cell network are determined by (smooth) vector fields that are consistent with the network structure. Here, we follow the formalisms of Stewart et al (2003 SIAM J. Appl. Dyn. Syst. 2, 609–646), Golubitsky et al (2005 SIAM J. Appl. Dyn. Syst. 4, 78–100) and Field (2004 Dyn. Syst. 19, 217–243). It is known that two non-isomorphic n-cell coupled networks can determine the same sets of vector fields - these networks are said to be ordinary differential equation (ODE)-equivalent. The set of all n-cell coupled networks is so partitioned into classes of ODE-equivalent networks. With no further restrictions, the number of ODE-classes is not finite and each class has an infinite number of networks. Inside each ODE-class we can find a finite subclass of networks that minimize the number of edges in the class, called minimal networks. In this paper, we consider coupled cell networks with asymmetric inputs. That is, if k is the number of distinct edges types, these networks have the property that every cell receives k inputs, one of each type. Fixing the number n of cells, we prove that: the number of ODE-classes is finite; restricting to a maximum of n(n − 1) inputs, we can cover all the ODE-classes; all minimal n-cell networks with n(n − 1) asymmetric inputs are ODE-equivalent. We also give a simple criterion to test if a network is minimal and we conjecture lower estimates for the number of distinct ODE-classes of n-cell networks with any number k of asymmetric inputs. Moreover, we present a full list of representatives of the ODE-classes of networks with three cells and two asymmetric inputs.
Towards a modification of a regulatory framework aiming at bunker oil spill prevention from ships - A design aspect of bunker tanks vents location guided by CFD simulations
- Przemysław Krata
- Jacek Jachowski
2021 RELIABILITY ENGINEERING & SYSTEM SAFETY
Although accidental bunker oil spills at seaway are relatively rare events, they can be pose real threat to the natural marine environment. One of the reasons for the bunker spill to occur is a design failure; one of the ways it can demonstrate is an improper location or height of vent heads, leading to a bunker oil discharge during heavy rolling, due to sloshing phenomenon. Design of a ship and her systems is guided by various formal conventions and ensuing requirements by classification societies, as a result of past experience and background knowledge. Nevertheless, the requirements are not always fully effective and up to date. An example of such situation is an accidental spill from a deep bunker tank, that has been arranged and designed according to the valid rules and regulations, however not accounting for dynamic physical phenomena that when occur lead to discharging the fuel through the vent. Therefore, the contemporary regulation of vent arrangement for some specific bunker tanks design options seems insufficient and requires scientific insight. To this end, we propose science-based regulatory framework modification. This is done through examining the location of the deep tank vent with regard to dynamics of the oil sloshing phenomenon, adopting CFD-based approach that is suitable for the purpose of onboard tank design. Moreover, an experimental validation of numerical simulations outcome is presented which makes the study credible. The proposed approach is both scientifically valid and practically feasible. Some CFD simulations of liquid sloshing need to be carried out for certain bunker tank design options. The additional burden at the design stage is not significantly time consuming thus remains justified, especially nowadays when CFD has become an industrial standard in some branches. The proposed solution attempts to improve the contemporary regulations in the area of bunker oil overflow prevention, reducing the negative impact of maritime transportation on the environmental safety.
Towards a multi-basin SWAT model for the migration of nutrients and pesticides to Puck Bay (Southern Baltic Sea)
- Paweł Wielgat
- Dominika Kalinowska
- Adam Szymkiewicz
- Piotr Zima
- Beata Jaworska-Szulc
- Ewa Wojciechowska
- Nicole Nawrot
- Karolina Matej-Łukowicz
- Lidia Anita Dzierzbicka-Glowacka
2021 Full text PeerJ
Background This paper analyzes the impact of changes in fertilization on crop yields and the runoff of nutrients from a small agricultural catchment (176 km2) to a shallow bay, using the SWAT model. Puck Bay is part of the Gulf of Gdansk and belongs to the Baltic Sea. The whole area of Puck Bay (364 km2) is protected (Natura 2000) yet despite this it suffers from eutrophication problems due to the relatively minimal depth and difficult water exchange. Methods The paper presents a comparison of the calculated yields and the runoff of nutrients and pesticides in the SWAT model, for a small agricultural coastal catchment. Calculations were made for 13 crop scenarios with weather data from 2011 to 2019. For each crop, an agriculture calendar was made. Two variants of fertilization were considered (autofertilization mode and according to the calendar). The nutrient runoff was calculated depending on the adopted scenario. In addition, the fate of selected pesticides was simulated. Results Depending on the crop, the annual load of NO3into the stream ranged from 0.74 to 3.65 kg ha−1. The annual load of organic phosphorous into the stream was between 0.686 and 3.64 kg ha−1. This is lower than in the majority of EU or Baltic countries. The surface runoff of dissolved Glyphosate was equal to 286 mg ha−1. The annual loads of nutrients from the catchment area are equivalent in both fertilization modes. Regardless of the selected fertilization mode, in addition to the dosage, the form of nutrients is important for the model.
Towards Cancer Patients Classification Using Liquid Biopsy
- Sebastian Cygert
- Franciszek Górski
- Piotr Juszczyk
- Sebastian Lewalski
- Krzysztof Pastuszak
- Andrzej Czyżewski
- Anna Supernat
2021
Liquid biopsy is a useful, minimally invasive diagnostic and monitoring tool for cancer disease. Yet, developing accurate methods, given the potentially large number of input features, and usually small datasets size remains very challenging. Recently, a novel feature parameterization based on the RNA-sequenced platelet data which uses the biological knowledge from the Kyoto Encyclopedia of Genes and Genomes, combined with a classifier based on the Convolutional Neural Network (CNN), allowed significantly improving the classification accuracy. In this work, we take a closer look at this approach and find that similar results can be obtained using significantly smaller models. Additionally, competitive results were achieved using gradient boosting. Since it has another advantage of adding interpretability to the model, we further analyze it in this work.
Towards Computer-Aided Graphene Covered TiO2-Cu/(CuxOy) Composite Design for the Purpose of Photoinduced Hydrogen Evolution
- Łukasz Lewandowski
- Agnieszka Gajewicz-Skretna
- Tomasz Klimczuk
- Grzegorz Trykowski
- Kostiantyn Nikiforow
- Wojciech Lisowski
- Anna Gołąbiewska
- Adriana Zaleska-Medynska
2021 Full text Catalysts
In search a hydrogen source, we synthesized TiO2-Cu-graphene composite photocatalyst for hydrogen evolution. The catalyst is a new and unique material as it consists of copper-decorated TiO2 particles covered tightly in graphene and obtained in a fluidized bed reactor. Both, reduction of copper from Cu(CH3COO) at the surface of TiO2 particles and covering of TiO2-Cu in graphene thin layer by Chemical Vapour Deposition (CVD) were performed subsequently in the flow reactor by manipulating the gas composition. Obtained photocatalysts were tested in regard to hydrogen generation from photo-induced water conversion with methanol as sacrificial agent. The hydrogen generation rate for the most active sample reached 2296.27 mol H2 h1 gcat 1. Combining experimental and computational approaches enabled to define the optimum combination of the synthesis parameters resulting in the highest photocatalytic activity for water splitting for green hydrogen production. The results indicate that the major factor affecting hydrogen production is temperature of the TiO2-Cu-graphene composite synthesis which in turn is inversely correlated to photoactivity.
TOWARDS EXPLAINABLE CLASSIFIERS USING THE COUNTERFACTUAL APPROACH - GLOBAL EXPLANATIONS FOR DISCOVERING BIAS IN DATA
- Agnieszka Mikołajczyk
- Michał Grochowski
- Arkadiusz Kwasigroch
2021 Full text Journal of Artificial Intelligence and Soft Computing Research
The paper proposes summarized attribution-based post-hoc explanations for the detection and identification of bias in data. A global explanation is proposed, and a step-by-step framework on how to detect and test bias is introduced. Since removing unwanted bias is often a complicated and tremendous task, it is automatically inserted, instead. Then, the bias is evaluated with the proposed counterfactual approach. The obtained results are validated on a sample skin lesion dataset. Using the proposed method, a number of possible bias-causing artifacts are successfully identified and confirmed in dermoscopy images. In particular, it is confirmed that black frames have a strong influence on Convolutional Neural Network’s prediction: 22% of them changed the prediction from benign to malignant.