2021 - Publications Repository - Gdańsk University of Technology

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Publications from the year 2021

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Self-assembly of vertically oriented graphene nanostructures: multivariate characterisation by Minkowski functionals and fractal geometry
- Mattia Pierpaoli
- Mateusz Ficek
- Paweł Jakóbczyk
- Jakub Karczewski
- Robert Bogdanowicz
2021 Full text ACTA MATERIALIA
The enormous self-assembly potential that graphene and its derived layered materials offer for responding to the contemporary environmental challenges has made it one of the most investigated materials. Hence, tuning its extraordinary properties and understanding the effect at all scales is crucial to tailoring highly customised electrodes. Vertically oriented graphene nanostructures, also known as carbon nanowalls (CNWs), due to the large surface area and unique maze-like morphology, have attracted attention as a platform for advanced sensing applications. In this work, a holistic investigation approach has been developed to disrupt the synthesis-composition-structure-property paradigm and to dig out the hidden materials relationships. To achieve that, autonomous advanced image-analysis methods (Minkowski Functionals, Fractal Analysis) have been applied to SEM micrographs and successfully classified them. Morphological, electrical, and electrochemical characterisation has been performed for all of the samples. Multivariate data analysis has been employed to mine the relationships between the material features, specifically as it relates to the understanding of the intrinsic properties. As a result, this study is intended to both shed light on CNWs as a promising transparent hybrid electrochemical substrate for perfectly assembled electrochemical devices and to provide a new flexible method for nanomaterial design, characterisation and exploitation.
Self-assembly, stability and conductance of amphotericin B channels: bridging the gap between structure and function
- Joanna Zielińska
- Miłosz Wieczór
- Paweł Chodnicki
- Ewa Grela
- Rafał Luchowski
- Łukasz Nierzwicki
- Tomasz Bączek
- Wiesław I. Gruszecki
- Jacek Czub
2021 NANOSCALE
Amphotericin B (AmB), one of the most powerful but also toxic drugs used to treat systemic mycoses, is believed to selectively permeabilize fungal cell membranes to ions in a sterol-dependent manner. Unfortunately, the structure of the biologically active AmB channels has long eluded researchers, obstructing the design of safer alternatives. Here, we investigate the structural and thermodynamic aspects of channel formation, stability, and selective ion conduction. We combine fluorescence lifetime imaging and molecular simulations to trace the process of channel assembly until the formation of stable, roughly octameric double-length channels (DLCs). This stoichiometry is confirmed by matching the predicted channel conductances with the past results of patch-clamp measurements. We then use free energy calculations to explain the effect of sterols on DLC stability and discuss the observed cation selectivity in structural terms, addressing several long-standing controversies in the context of their physiological relevance. Simulations of ion permeation indicate that only solvated ions pass through DLCs, revealing surprising solvation patterns in the channel lumen. We conclude our investigation by inspecting the role of the tail hydroxyl in the assembly of functional channels, pointing at possible origins of the cholesterol–ergosterol selectivity.
Self-assessment of competencies of students and graduates participating in didactic projects – Case study
- Małgorzata Gawrycka
- Justyna Kujawska
- Michał Tomczak
2021 Full text International Review of Economics Education
Aim/purpose: the aim of this article is to examine the opinions of students and graduates of the faculty of economics of a technical university as regards their selfassessment of their preparation for entering the modern labour market. All the respondents participated during their studies in didactic projects aimed at improving their competencies taking into account the expectations of potential employers. Design/methodology/approach: the study was quantitative in nature and was carried out using the CAWI method. In the analysis of the study results, elements of descriptive statistics were used, such as: mean measures, structure indicators, structure similarity indicators and tests for the significance of mean values. A comparative analysis was conducted between two groups of respondents – students and graduates. Findings: the conducted study shows that by organising additional training for students, the university contributes to supplementing their theoretical and practical knowledge in the area of competencies required by the labour market today, in particular within the scope of specialist and technical competencies which are becoming indispensable in the Economy 4.0. Research implications/limitations: due to the small size of the test sample, the results should be treated with caution, are not representative and constitute only a case study. Originality/value/contribution: the results of the research confirm the importance of lifelong learning as regards reducing the competence gap among university graduates. The tools used in the above-mentioned process include additional training activities, such as the presented didactic projects addressed to students, complementary to the curriculum of studies. They enabled the students to extend their competencies even before they left the walls of the university and, as a result, facilitated their entry into the labour market.
Self-employment of women: an opportunity or the last resort?
- Dagmara Nikulin
2021
It is believed that automatization and technological changes will be the main drivers of work in the future. At the same time, there is a growing discussion about new forms of employment, such as self-employment. It may be either perceived as a chance for empowerment, through creating new job opportunities, that were not reachable previously, or as precarious work, with less stability, higher risk, and uncertain income. The main goal of this work is to analyze what makes women choose self-employment. Our cross-country study, conducted for 31 European countries based on 2014 European Labour Force Survey (LFS), brings a new perspective on the phenomenon. Our results suggest that self-employment may constitute an opportunity for women as higher level of skills and older age increase the probability of becoming self-employed. Moreover, as skilled people predominantly show greater skills related to the use of technology, one may conclude that the use of ICT may reinforce this form of work. On the other hand, self-employed women’s work is to a greater extent based on part-time arrangements and is frequently performed in the evenings. For this reason, it may be concluded that self-employment is an option for women who have to combine family life with work and have no chance to find typical paid employment.
Self-Organising map neural network in the analysis of electromyography data of muscles acting at temporomandibular joint.
- Mateusz Troka
- Wiktoria Wojnicz
- Katarzyna Szepietowska
- Izabela Lubowiecka
2021
The temporomandibular joint (TMJ) is the joint that via muscle action and jaw motion allows for necessary physiological performances such as mastication. Whereas mandible translates and rotates [1]. Estimation of activity of muscles acting at the TMJ provides a knowledge of activation pattern solely of a specific patient that an electromyography (EMG) examination was carried out [2]. In this work, a Self-Organising Maps (SOMs) based method was used to identify a hidden similarities in EMG data between different patients. Artificial Neural Network algorithm used for this work – Supervised Kohonen Network (SKN) was proposed and described in [3] and extended into a MATLAB toolbox by [4]. SKN algorithm was used to simulate the model, resulting in a chart called class profiles describing the calculated averages of the Kohonen weights of each variable. It shows how data similarity coming from different subjects is distributed. The obtained results let one to draw a conclusion about muscle significance during specific motion. This SOM based modelling method was intended to estimate TMJ instability and its muscle performance during jaw motions. The study was an attempt to identify and categorise patients with similarly possible disorders in TMJ area which can be evaluated from their muscles activation data.
Semantic segmentation training using imperfect annotations and loss masking
- Adam Brzeski
- Jan Cychnerski
- Tomasz Dziubich
- Tomasz Gilewicz
- Jan Woś
2021
One of the most significant factors affecting supervised neural network training is the precision of the annotations. Also, in a case of expert group, the problem of inconsistent data annotations is an integral part of real-world supervised learning processes, well-known to researchers. One practical example is a weak ground truth delineation for medical image segmentation. In this paper, we have developed a new method of accurate segmentation of blood vessels based on a convolutional neural network. We focused on imperfect annotations for the semantic segmentation of blood vessels and introduced a concept of uncertainty masks and loss masking. These uncertainty masks can be created roughly by non-experts, which makes annotation process cheaper and faster. Quantitative results of our method on a real-world problem with missing annotations and on a perfectly labeled data set with artificially introduced noise are presented. Models trained with loss masking seem to be more robust regardless of the number of removed vessels. Noise robustness of four different model architectures has been tested and compared to the loss masking method, which turned out to have better performance during training on noisy data
SENSITIVITY ANALYSIS IN THE REHABILITATION OF HISTORIC TIMBER STRUCTURES ON THE EXAMPLES OF GREEK CATHOLIC CHURCHES IN POLISH SUBCARPATHIA
- Katarzyna Szepietowska
- Izabela Lubowiecka
2021
This work concerns structural and sensitivity analysis of carpentry joints used in historic wooden buildings in south-eastern Poland and western Ukraine. These are primarily sacred buildings and the types of joints characteristic for this region are saddle notch and dovetail joints. Thus, in the study the authors focus on these types of corner log joints. Numerical models of the joints are defined and finite element simulations of their statics are carried out. Moreover, a sensitivity analysis is performed in order to describe how the uncertainty of material properties including humidity of some structural members, caused during potential repairs, affect the structural behaviour of the whole connection. This represents the situation when some degraded logs are exchanged into new wood combining old, and often damp, wood with new and dry logs. A non-intrusive probabilistic approach to the sensitivity analysis is applied and regression-based Polynomial Chaos (PC) expansion method is used to propagate uncertainties.
Sensors and Sensor’s Fusion in Autonomous Vehicles
- Andrzej Stateczny
- Marta Wlodarczyk-Sielicka
- Paweł Burdziakowski
2021 Full text SENSORS
Autonomous vehicle navigation has been at the center of several major developments, both in civilian and defense applications. New technologies such as multisensory data fusion, big data processing, and deep learning are changing the quality of areas of applications, improving the sensors and systems used. New ideas such as 3D radar, 3D sonar, LiDAR, and others are based on autonomous vehicle revolutionary development. The Special Issue entitled “Sensors and Sensor’s Fusion in Autonomous Vehicles” was focused on many aspects of autonomous vehicle sensors and their fusion, such as autonomous navigation, multi-sensor fusion, big data processing for autonomous vehicle navigation, sensors related to science/research, algorithms/technical development, analysis tools, synergy with sensors in navigation, and artificial intelligence methods for autonomous vehicle navigation.
Sequence-dependent structural properties of B-DNA: what have we learned in 40 years?
- Gabriela da Rosa
- Leandro Grille
- Victoria Calzada
- Katya Ahmad
- Juan Pablo Arcon
- Federica Battistini
- Genís Bayarri
- Thomas Bishop
- Paolo Carloni
- Thomas Cheatham III
- Rosana Collepardo-Guevara
- Jacek Czub
- Jorge R. Espinosa
- Rodrigo Galindo-Murillo
- Sarah A. Harris
- Adam Hospital
- Charles Laughton
- John H. Maddocks
- Agnes Noy
- Modesto Orozco
- Marco Pasi
- Alberto Pérez
- Daiva Petkevičiūtė-Gerlach
- Rahul Sharma
- Ran Sun
- Pablo D. Dans
2021 Full text Biophysical Reviews
The structure of B-DNA, the physiological form of the DNA molecule, has been a central topic in biology, chemistry and physics. Far from uniform and rigid, the double helix was revealed as a flexible and structurally polymorphic molecule. Conformational changes that lead to local and global changes in the helix geometry are mediated by a complex choreography of base and backbone rearrangements affecting the ability of the B-DNA to recognize ligands and consequently on its functionality. In this sense, the knowledge obtained from the sequence-dependent structural properties of B-DNA has always been thought crucial to rationalize how ligands and, most notably, proteins recognize B-DNA and modulate its activity, i.e. the structural basis of gene regulation. Honouring the anniversary of the first high-resolution X-ray structure of a B-DNA molecule, in this contribution, we present the most important discoveries of the last 40 years on the sequence-dependent structural and dynamical properties of B-DNA, from the early beginnings to the current frontiers in the field.
Series-Slot-Fed Circularly Polarized Multiple-Input-Multiple-Output Antenna Array Enabling Circular Polarization Diversity for 5G 28-GHz Indoor Applications
- Ubaid Ullah
- Muath Al-hasan
- Ismail Mabrouk
- Sławomir Kozieł
2021 Full text IEEE TRANSACTIONS ON ANTENNAS AND PROPAGATION
In this paper, a four-element circularly polarized series-slot-fed multiple-input-multiple-output (MIMO) antenna array with circular polarization diversity is presented. The proposed design utilizes a combination of 45-degree inclined slots and a straight microstrip line feeding technique. The two antennas are designed to operate with the opposite sense of circular polarization (CP). CP is achieved by placing a patch of just about square dimensions on the top of the V-slot with orthogonal but unequal arms. The unequal arm of the slot degenerates the fundamental mode at a slightly different frequency with 90-degree phase difference occurring at the center frequency of each arm. Proper positioning of the patch on the top of the slot ensures excitation of CP. For realizing a MIMO antenna with different sense of polarization, both the slots and the patches are flipped with respect to the feedline. Following optimization at the full-wave level of description, the antenna is prototyped and validated experimentally. The realizable antenna footprint is 20 mm × 27.7 mm. The simulated and measured results indicate that the proposed antenna features a wide impedance bandwidth (|S11|<-10 dB) from 26.9 GHz to 30.7 GHz, 3 dB axial ratio bandwidth from 27.31 GHz to 29.65 GHz and the peak realized gain of 11.86 dBic. Moreover, it exhibits a low level of in-band isolation |S21|>-37 dB and almost negligible envelope correlation coefficient (ECC), less than 0.00025. The highly directional beams, high gain and compact size of the proposed antenna permit implementation of multiple antennas for indoor applications in the 28-GHz band.
Serotonergic–Muscarinic Interaction within the Prefrontal Cortex as a Novel Target to Reverse Schizophrenia-Related Cognitive Symptoms
- Paulina Cieślik
- Adrianna Radulska
- Grzegorz Burnat
- Leszek Kalinowski
- Joanna M. Wierońska
2021 Full text INTERNATIONAL JOURNAL OF MOLECULAR SCIENCES
Recent studies revealed that the activation of serotonergic 5-HT1A and muscarinic M1, M4, or M5 receptors prevent MK-801-induced cognitive impairments in animal models. In the present study, the effectiveness of the simultaneous activation of 5-HT1A and muscarinic receptors at preventing MK-801-induced cognitive deficits in novel object recognition (NOR) or Y-maze tests was investigated. Activators of 5-HT1A (F15599), M1 (VU0357017), M4 (VU0152100), or M5 (VU0238429) receptors administered at top doses for seven days reversed MK-801-induced deficits in the NOR test, similar to the simultaneous administration of subeffective doses of F15599 (0.05 mg/kg) with VU0357017 (0.15 mg/kg), VU0152100 (0.05 mg/kg), or VU0238429 (1 mg/kg). The compounds did not prevent the MK-801-induced impairment when administered acutely. Their activity was less evident in the Y-maze. Pharmacokinetic studies revealed high brain penetration of F15599 (brain/plasma ratio 620%), which was detected in the frontal cortex (FC) up to 2 h after administration. Decreases in the brain penetration properties of the compounds were observed after acute administration of the combinations, which might have influenced behavioral responses. This negative effect on brain penetration was not observed when the compounds were administered repeatedly. Based on our results, prolonged administration of a 5-HT1A activator with muscarinic receptor ligands may be effective at reversing cognitive decline related to schizophrenia, and the FC may play a critical role in this interaction.
Service-based Resilience via Shared Protection in Mission-critical Embedded Networks
- Doganalp Ergenc
- Jacek Rak
- Mathias Fischer
2021 Full text IEEE Transactions on Network and Service Management
Mission-critical networks, which for example can be found in autonomous cars and avionics, are complex systems with a multitude of interconnected embedded nodes and various service demands. Their resilience against failures and attacks is a crucial property and has to be already considered in their design phase. In this paper, we introduce a novel approach for optimal joint service allocation and routing, leveraging virtualized embedded devices and shared backup capacity for the fault-tolerant design of mission-critical networks. This approach operates in phases utilizing multiple optimization models. Furthermore, we propose a new heuristic that ensures resource efficiency and fault-tolerance against single node and link failures as pre-requisite for resilience. Our experiments for different application scenarios indicate that our heuristic achieves results close to the optimum and provides 50% of capacity gain compared to a dedicated capacity protection scheme. Moreover, our heuristic ensures fault-tolerance against at least 90% of all potential single node failures.
Seven Different Lighting Conditions in Photogrammetric Studies of a 3D Urban Mock-Up
- Katarzyna Bobkowska
- Paweł Burdziakowski
- Jakub Szulwic
- Karolina Zielińska-Dąbkowska
2021 Full text ENERGIES
One of the most important elements during photogrammetric studies is the appropriate lighting of the object or area under investigation. Nevertheless, the concept of “adequate lighting” is relative. Therefore, we have attempted, based on experimental proof of concept (technology readiness level—TRL3), to verify the impact of various types of lighting emitted by LED light sources for scene illumination and their direct influence on the quality of the photogrammetric study of a 3D urban mock-up. An important issue in this study was the measurement and evaluation of the artificial light sources used, based on illuminance (E), correlated colour temperature (CCT), colour rendering index (CRI) and Spectral power distribution (SPD) and the evaluation of the obtained point clouds (seven photogrammetric products of the same object, developed for seven different lighting conditions). The general values of the quality of the photogrammetric studies were compared. Additionally, we determined seventeen features concerning the group of tie-points in the vicinity of each F-point and the type of study. The acquired traits were related to the number of tie-points in the vicinity, their luminosities and spectral characteristics for each of the colours (red, green, blue). The dependencies between the identified features and the obtained XYZ total error were verified, and the possibility of detecting F-points depending on their luminosity was also analysed. The obtained results can be important in the process of developing a photogrammetric method of urban lighting monitoring or in selecting additional lighting for objects that are the subject of a short-range photogrammetric study.
Shadow Economy in Poland Recent Evidence Based on Survey Data
- Dagmara Nikulin
- Ewa Lechman
2021
The book provides an estimate of the size of the shadow economy in Poland. Using analogous data, it traces core determinants of the existence of the shadow economy in Poland. It compares results with neighbouring countries, and if possible, the remaining Central-Eastern economies. The book tells why the problem of the unreported economic activity matters; it presents the problem from different angles―economic, social and institutional. Next, it extensively reviews past research on the size and determinants of the shadow economy in Poland. It discusses available resources and empirical results showing the problem from micro-, and macroeconomic perspective. The authors present the methods used and the results of the survey, which are interpreted and discussed Finally it concludes on major drivers of shadow economy in Poland, providing recommendations and future research directions. The book is intended for practitioners and those seeking understanding of undeclared economic activities.
Shaft friction from the DMT and direct shear interface tests
- Kamila Mikina
- Jakub Konkol
- Lech Bałachowski
2021
The article presents preliminary attempt to create tri-linear transfer curves for describing pile behaviour under axial loading. Transfer curves would use the parameter measured in dilatometer test, particularly a constrained modulus MDMT. The proposed method is based on concrete rough and smooth interface tests performed in a direct shear apparatus. Based on the obtained mobilization curves, relationships were created between the parameters describing the slope of individual transfer curves and the MDMT modulus. The obtained correlations were used to estimate the capacity of the concrete screw pile subjected to the static load test in tension.
Shape and force control of cable structures with minimal actuators and actuation
- Najmadeen Saeed
- Ahmed Manguri
- Abubakr Adabar
2021 International Journal of Space Structures
Shape adjustment and stress control can be considered as one of the effective parameters in prestressed cable structures since such structures are widely constructed nowadays due to their characteristics. The assembly errors and applied loads hugely affect the cables’ nodal positions and stress due to their delicacy. The former could disturb the shape, which affects the appearance and the function of the structure. In contrast, the latter may increase the stress in some cables above the upper limit or induce slack in some others. Accordingly, a technique has been proposed that combined fmincon optimization that relies on four different algorithms with a controlling approach based on the force method. The presented method aims to minimize the total amount of actuation and miniaturize the number of actuators. The targets of previously confirmed techniques can be obtained with less actuation and fewer actuators by using the current technique. Based on the verified examples, the advantage of the current approach over the quoted methods is up to 55% and 37% in terms of the number of actuators and the total amount of actuation, respectively.
Shape Memory Materials from Rubbers
- Arunima Reghunadhan
- Paduvilan Jibin
- Vayyaprontavida Kaliyathan
- Prajitha Velayudhan
- Michał Strankowski
- Sabu Thomas
2021 Full text Materials
Smart materials are much discussed in the current research scenario. The shape memory effect is one of the most fascinating occurrences in smart materials, both in terms of the phenomenon and its applications. Many metal alloys and polymers exhibit the shape memory effect (SME). Shape memory properties of elastomers, such as rubbers, polyurethanes, and other elastomers, are discussed in depth in this paper. The theory, factors impacting, and key uses of SME elastomers are all covered in this article. SME has been observed in a variety of elastomers and composites. Shape fixity and recovery rate are normally analysed through thermomechanical cycle studies to understand the effectiveness of SMEs. Polymer properties such as chain length, and the inclusion of fillers, such as clays, nanoparticles, and second phase polymers, will have a direct influence on the shape memory effect. The article discusses these aspects in a simple and concise manner.
Shape-Memory Polyurethane Polymers
- Michał Strankowski
- Paul Anju
- Arunima Reghunadhan
2021 Full text ACS SYMPOSIUM SERIES
Polyurethanes (PUs) are one of the most widely used polymers in research and industry. They can be synthesized from chemical sources and natural sources. PUs are a very useful class of polymers and exhibit many desirable properties that can be exploited in various applications. PUs are formed by the reaction between polyols and isocyanates. A wide variety of polyols and isocyanates are available for synthesis, and hence we can produce a large number of PUs. PUs show high mechanical strength, chemical resistance, flexibility, and resilience. One of the major advantages of some specially designed PUs is their ability to recover their primary shape, which is known as shape memory. The shape-memory effect (SME) of PUs makes them popular in biomedical, electronic, and thermal applications. The SME can be monitored using different measures such as shape fixity, recovery time, and recovery rate. Various stimuli are applied to shape-memory materials to induce shape memory. PU polymers can be modified with different nanofillers, and these fillers influence the shape-recovery parameters. PU composites are popular because of a good property–price relationship. This chapter discusses the various factors affecting the SME of PU composites and the effect of different types of fillers on the PU matrix.
Shaping the City Responding to Climate Change – Concept of Development of the Right Bank of the Vistula River in Toruń, Poland,
- Sylwia Sitniewska
- Justyna Borucka
2021
The problems of cities of the 21st century are caused by anthropogenic oppression of the environment, through the growth of economic activity and continuous urbanisation, and taking away ecologically important open areas and biologically active areas. Increasingly frequent and sudden rains, strong winds, turbulence and rising world water levels are some of the consequences of climate change that have a direct impact on the functioning of cities. The article presents a study of a land-use plan for the right bank of the Vistula river in Toruń, Poland, in reference to ongoing climate change. The authors focus on the main assumption of this concept, which is to protect the area from increasing river floods expected due to strong climate change impact on Earth’s water cycle and temporary river water rise. The project strategy focussed on reshaping the Vistula river bank, as well as designing a solution that would allow floodwater to enter the area in a controlled manner. The newly designed area presented in the article is an attempt at conscious urban planning as well as planning activities in harmony with nature, and shows how such an approach to city planning can face the problems of climate change and could be a possible solution for future development of the city of Toruń.
Shear band evolution phenomena in direct shear test modelled with DEM.
- Michał Nitka
- Aleksander Grabowski
2021 Full text POWDER TECHNOLOGY
A direct shear test is widely used in the geotechnical engineering field. It is an easy and quick test to measure the shear properties of soil. This test often replaces more expensive and difficult tri-axial shear test. Despite that the direct shear test is known and used for a long time, it is still not well investigated at the grain scale. This paper deals with the micro behaviour of the cohesionless sand inside the direct shear box during a geotechnical test. Numerical calculations were performed with open-source discrete code YADE. The full 3D model was used, in order to eliminate some non-physical phenomena. The numerical stress-strain curve was directly compared with the laboratory results and good agreement was obtained. The focus was on the shape of the localized zone, the properties of this zone and its behaviour. The movement of the individual grains was studied. In our analysis, the stresses were also taken into consideration. The conclusions were validated on tests with different initial void ratio (dense or loose material) and with different vertical pressure.