2020 - Publications Repository - Gdańsk University of Technology

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Publications from the year 2020

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Evaluation of the resistance of steel–concrete adhesive connection in reinforced concrete beams using guided wave propagation
- Beata Zima
- Rafał Kędra
2020 Archives of Civil and Mechanical Engineering
The development of the nondestructive diagnostic methods is of significant importance in the last decades. A special attention is paid to diagnostics of reinforced concrete structures, which are very popular in the civil engineering field. A possible use of the guided waves in the estimation of the resistance of steel–concrete adhesive connection is studied in the following paper. The relationships relating adhesive connection resistance and wave propagation characteristics (wave velocity and the time of flight) have been derived and experimentally verified during pull-out tests conducted on a number of reinforced concrete beams varying in the debonding area. The pull-out tests were also monitored ultrasonically. On the basis of the results in the form of the time-domain signals, the theoretical load-carrying capacities of the pulled-out bars have been calculated and compared with the exact experimentally determined values. The high agreement of the results obtained proved the correctness of the developed method. Moreover, the signals registered during pull-out tests allowed to observe the changes of the wave velocity induced by the deterioration of the adhesive connection.
Evaluation of the significance of the effect of the active cross-sectional area of the inlet air channel on the specific enthalpy of the exhaust gas of a diesel engine using statistics F of the Fisher-Snedecor distribution
- Patrycja Puzdrowska
2020 Full text Combustion Engines
This paper presents the application of Fisher-Snedecor distribution F statistics to assess the significance of the influence of changes in the active cross-sectional area of the inlet air channel (Adol) flow in a diesel engine on the observed diagnostic parameter determined on the basis of measurements of the quick changing exhaust gas temperature in the outlet channel, which is the specific enthalpy of the exhaust gas stream within one engine operating cycle (hspal). A plan of experimental tests carried out on the laboratory stand of a single-cylinder Farymann Diesel type D10 laboratory engine was presented and the method of determination of F statistics values for the obtained measurement results was characterized. Representative results of calculations were presented and the strength of Adol input parameter influence on the determined diagnostic parameter hspal simplified physical model of the working process of a compression ignition engine as the object of diagnosis was evaluated. It is planned to further develop the experimental research program to determine the significance of the influence of changes in the values of selected parameters of the engine structure on other diagnostic measures determined from the exhaust gas temperature signal, i.e. the mean peak-to-peak value as well as the rate (intensity) of increase and decrease in its value for individual engine cycles.
Evidence of mutations conferring resistance to clarithromycin in wastewater and activated sludge
- Anna Gnida
- Ewa Felis
- Aleksandra Ziembińska-Buczyńska
- Aneta Łuczkiewicz
- Joanna Surmacz-Górska
- Krystyna Olańczuk-Neyman
2020 3 Biotech
The occurrence of clarithromycin in wastewater samples and of the activated sludge bacteria possibly resistant to this pharmaceutical was the object of the study. Samples of wastewater or activated sludge were taken from a municipal wastewater treatment plant in summer and winter and characterised regarding their clarithromycin concentrations and the presence of nucleic acid fragments (Cla-sequences) known to be responsible for clarithromycin resistance in Helicobacter pylori. The concentrations of clarithromycin in raw wastewater were about 1086-2271 ng/L. Around 50-60% less of the pharmaceutical was found in treated wastewater. The concentrations were much higher in winter samples, as compared to summer samples. The clarithromycin resistance markers in H. pylori were detected by fluorescence in situ hybridisation in activated sludge bacterial cells. Cla-sequences were found in all the detected Proteobacteria, independently of the sampling season. Among nitrifying or phosphate or glycogen accumulating bacteria only Nitrosomonas spp. revealed presence of the clarithromycin sequences.
Evolution of Ag nanostructures created from thin films: UV–vis absorption and its theoretical predictions
- Robert Kozioł
- Marcin Łapiński
- Paweł Syty
- Damian Koszelow
- Wojciech Sadowski
- Józef Eugeniusz Sienkiewicz
- Barbara Kościelska
2020 Full text Beilstein Journal of Nanotechnology
Ag-based plasmonic nanostructures were manufactured by thermal annealing of thin metallic films. Structure and morphology were studied using scanning electron microscopy (SEM), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HR-TEM) and X-ray photoelectron spectroscopy (XPS). SEM images show that the formation of nanostructures is influenced by the initial layer thickness as well as the temperature and the time of annealing. The Ag 3d and Ag 4d XPS spectra are characteristic of nanostructures. The quality of the nanostructures, in terms of their use as plasmonic platforms, is reflected in the UV–vis absorption spectra. The absorption spectrum is dominated by a maximum in the range of 450–500 nm associated with the plasmon resonance. As the initial layer thickness increases, an additional peak appears around 350 nm, which probably corresponds to the quadrupole resonance. For calculations leading to a better illustration of absorption, scattering and overall absorption of light in Ag nanoparticles, the Mie theory is employed. Absorbance and the distribution of the electromagnetic field around the nanostructures are calculated by finite-difference time-domain (FDTD) simulations. For calculations a novel approach based on modelling the whole sample with a realistic shape of the nanoparticles, instead of full spheres, was used. This led to a very good agreement with the experiment.
Evolution of magnetic and transport properties in (Cr1−xMnx)2AlC MAX-phase synthesized by arc melting technique
- Kirill V. Sobolev
- Kamil Kolincio
- Andrey Emelyanov
- Aleksandra Mielewczyk-Gryń
- Maria Gazda
- Marta Roman
- Anna Pazniak
- Valeria Rodionova
2020 JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS
Herein we initiate a comeback to the arc melting technique to produce MAX-phase solid solutions. Bulk samples of (Cr1−xMnx)2AlC MAX-phase with X = 0, 0.025, 0.05 and 0.1 were synthesized and studied by means of X-ray diffractometry, scanning electron microscopy in combination with energy-dispersive X-ray spectroscopy. Samples were established to be homogeneous with an incorporation of Cr7C3, AlCr2 and Al2O3 secondary phases which is slightly increasing with the raise of the dopant concentration. Manganese successfully intermixes in the MAX-phase structure due to the effect of the high-energetic plasma during the melting process. SQUID magnetometry identified the co-existence of ferro- and antiferromagnetic interactions with the latter prevailing in high temperatures and being attributed to the MAX-phase. Magnetic state transitions were observed at approximately 4 K and 5 K for doped samples which was associated with the presence of the marginal amount of ferromagnetic Mn-based secondary phases. The negative component of magnetoresistance was observed in highly doped samples at low temperatures that is likely due to the influence of ferromagnetic secondary phases as well. Transport properties measurement revealed the satisfactory quality of the produced samples.
Evolution of the HVDC Link Connecting Offshore Wind Farms to Onshore Power Systems
- Roland Ryndzionek
- Łukasz Sienkiewicz
2020 Full text ENERGIES
This paper presents an overview of the DC link development and evolution dedicated to HVDC structure for connecting offshore wind power plants to onshore power systems. The growing demand for the green energy has forced investors in power industry to look for resources further out at sea. Hence, the development of power electronics and industrial engineering has enabled offshore wind farms to be situated further from the shore and in deeper waters. However, their development will require, among other technologies, DC-DC conversion systems. The advantages of HVDC over HVAC technology in relation to transmission distance are given. The different HVDC configurations and topologies of HVDC converters are elucidated. In this context, the HVDC grids are a promising alternative for the expansion of the existing AC grid.
EVOLUTIONARY MULTI–OBJECTIVE WEATHER ROUTING OF SAILBOATS
- Ewa Sobecka
- Rafał Szłapczyński
- Marcin Życzkowski
2020 Full text Polish Maritime Research
The paper presents a multi-objective method, which optimises the route of a sailboat. The presented method makes use of an evolutionary multi-objective (EMO) algorithm, which performs the optimisation according to three objective functions: total passage time, a sum of all course alterations made during the voyage and the average angle of heel. The last two of the objective functions reflect the navigator’s and passenger’s comfort, which may decrease with multiple turns or when experiencing an excessive heel angle for a long time. The optimisation process takes into account static bathymetry-related constraints as well as dynamic constraints related to the sailboat’s safety in changing wind and wave conditions. The method makes use of all of the above and finally returns an approximated Pareto set containing non-dominated solutions to the optimisation problem. The developed method has been implemented as a simulation application. The paper includes selected simulation results followed by their discussion.
E-Voting System Evaluation Based on the Council of Europe Recommendations: nVotes
- David Yeregui
- David Duenas Cid
- Hector Moretón
2020 Full text
E-voting implantation has been facing important challenges in recent years. Several incidents, together with a lack of evaluation methodologies social and cultural customs hinder a broader application. In this work, the authors aim to contribute to a safer introduction of e-voting tools by applying a practical evaluation framework strongly based on the security requirements issued by the Council of Europe (CoE) in 2017 to nvotes, a system that has been utilized to cast over 2 million votes over the last 6 years. The ultimate goal of the analysis is not to judge from a rigid, “infallible” but to contribute to a gradual and secure implementation of e-voting solutions in the democratic processes. The authors believe it can constitute a useful source of information for election officials, researchers and voters.
Exchange-Traded Funds on European Markets: Has Critical Mass been Reached? Implications for Financial Systems.
- Adam Marszk
- Ewa Lechman
2020 Full text ENTROPY
Exchange-traded funds (ETFs) are one of the most rapidly expanding categories of financial products in Europe. One of the key yet still unanswered questions is whether European ETF markets have reached the size at which they could affect the financial systems. In our study, we examine 13 European countries during the period 2004–2017 in order to trace whether the share of ETFs in the total assets of investment funds has reached the ‘critical’ level that makes possible their further growth and can be associated with an influence on the financial system. We use a novel methodological approach that identifies the ‘critical mass’ along diffusion trajectories. Our results show that, in 10 countries, the share of ETFs in assets of investment funds increased. Still, in most countries, the share of ETFs did not exceed 1%. Estimates of the diffusion models indicate that the process of growing shares of ETFs was most dynamic and relatively most stable in Switzerland and United Kingdom. Results of the critical mass analysis imply that its achievement may be forecasted exclusively in these two cases. However, even in such cases there is no substantial evidence for a possible significant influence of ETFs on the local financial systems.
Excited states of isoxazole molecules studied by electron energy-loss spectroscopy
- Ireneusz Linert
- Mariusz Zubek
2020 Full text JOURNAL OF ELECTRON SPECTROSCOPY AND RELATED PHENOMENA
Electron energy-loss spectra were measured in isoxazole in the excitation energy range 3.5−10 eV to investigate the valence excited states. Spectra recorded at different scattering conditions enabled the identification of the singlet and triplet states and the determination of their vertical excitation energies. The two lowest energy triplet bands, ππ* 13A' and ππ* 23A' at 4.20 and 5.30 eV, respectively show vibrational progressions. The first triplet state, 15a'π* 13A” that involves excitation from the nitrogen lone-pair orbital is observed at 5.68 eV. The three singlet valence states, ππ* 11A', nNπ* 11A” and ππ* 21A' are observed at 5.96, 6.49 and 6.88 eV, respectively in accord with the absorption measurements. Resonance excitation of the triplet and singlet states was noticed.
Exhaled breath analysis by resistive gas sensors
- Tomasz Chludziński
- Andrzej Kwiatkowski
2020 Full text Metrology and Measurement Systems
Breath analysis has attracted human beings for centuries. It was one of the simplest methods to detect various diseases by using human smell sense only. Advances in technology enable to use more reliable and standardized methods, based on different gas sensing systems. Breath analysis requires the detection of volatile organic compounds (VOCs) of the concentrations below individual ppm (parts per million). Therefore, advanced detection methods have been proposed. Some of these methods use expensive and bulky equipment (e.g. optical sensors, mass spectrometry – MS), and require time-consuming analysis. Less accurate, but much cheaper, are resistive gas sensors. These sensors use porous materials and adsorptiondesorption processes, determining their physical parameters. We consider the problems of applying resistive gas sensors to breath analysis. Recent advances were underlined, showing that these economical gas sensors can be efficiently employed to analyse breath samples. General problems of applying resistive gas sensors are considered and illustrated with examples, predominantly related to commercial sensors and their long-term performance. A setup for collection of breath samples is considered and presented to point out the crucial parts and problematic issues.
Expedited antenna optimization with numerical derivatives and gradient change tracking
- Anna Pietrenko-Dąbrowska
- Sławomir Kozieł
2020 Full text ENGINEERING COMPUTATIONS
Design automation has been playing an increasing role in the development of novel antenna structures for various applications. One of its aspects is electromagnetic (EM)-driven design closure, typically applied upon establishing the antenna topology, and aiming at adjustment of geometry parameters to boost the performance figures as much as possible. Parametric optimization is often realized using local methods given usually reasonable quality of the initial designs obtained at the topology evolution stage. The major difficulty here is high computational cost associated with a large number of EM simulations required by conventional methods, both gradient and derivative-free routines. Possible workarounds including surrogate-assisted variable-fidelity methods (e.g., space mapping) face similar problems because the underlying low-fidelity model is often optimized directly. This paper proposes an expedited version of the trust-region (TR) gradient-based algorithm with numerical derivatives. A considerable reduction of the number of EM simulations is achieved by monitoring the behavior of the gradient throughout the algorithm run and omitting the finite-differentiation updates upon detecting stable patterns for particular parameter sensitivities. The proposed approach is benchmarked against the standard TR algorithm as well as the recently reported accelerated TR frameworks. Improved performance is consistently demonstrated for all considered test cases.
Expedited Design Closure of Antenna Input Characteristics by Trust Region Gradient Search and Principal Component Analysis
- Jon Tomasson
- Sławomir Kozieł
- Anna Pietrenko-Dąbrowska
2020 Full text IEEE Access
Optimization-based parameter tuning has become an inherent part of contemporary antenna design process. For the sake of reliability, it is typically conducted at the level of full-wave electromagnetic (EM) simulation models. This may incur considerable computational expenses depending on the cost of an individual EM analysis, the number of adjustable variables, the type of task (local, global, single-/multi-objective optimization), and the constraints involved. For these reasons, utilization of conventional algorithms is often impractical. This paper proposes a novel gradient-based algorithm with numerical derivatives for expedited antenna optimization. The improvement of computational efficiency is obtained by employing a rank-one Broyden formula and restricting finite differentiation sensitivity updates to the principal directions of the Jacobian matrix, i.e., those corresponding to the most significant changes of the antenna responses. Comprehensive numerical validation carried out using three wideband antennas indicates that the presented methodology offers considerable savings of sixty percent with respect to the reference trust-region algorithm. At the same time, virtually no degradation of the design quality is observed. Furthermore, algorithm reliability is greatly improved (while offering comparable computational efficiency) over the recent state-of-the-art accelerated gradient-based procedures.
Expedited Feature-Based Quasi-Global Optimization of Multi-Band Antenna Input Characteristics with Jacobian Variability Tracking
- Sławomir Kozieł
- Anna Pietrenko-Dąbrowska
2020 Full text IEEE Access
Design of modern antennas relies—for reliability reasons—on full-wave electromagnetic simulation tools. In addition, increasingly stringent specifications pertaining to electrical and field performance, growing complexity of antenna topologies, along with the necessity for handling multiple objectives, make numerical optimization of antenna geometry parameters a highly recommended design procedure. Conventional algorithms, particularly global ones, entail often-unmanageable computational costs, so alternative approaches are needed. This work proposes a novel method for cost-efficient globalized design optimization of multi-band antennas incorporating the response feature technology into the trustregion framework. It allows for unequivocal allocation of the antenna resonances even for poor initial designs, where conventional local algorithms fail. Furthermore, the algorithm is accelerated by means of Jacobian variability tracking, which reduces the number of expensive finite-differentiation updates. Two real-world antenna design cases are used for demonstration purposes. The optimization cost is comparable to that of local routines while ensuring nearly global search capabilities.
Expedited Globalized Antenna Optimization by Principal Components and Variable-Fidelity EM Simulations: Application to Microstrip Antenna Design
- Jon Tomasson
- Anna Pietrenko-Dąbrowska
- Sławomir Kozieł
2020 Full text Electronics
Parameter optimization, also referred to as design closure, is imperative in the development of modern antennas. Theoretical considerations along with rough dimension adjustment through supervised parameter sweeping can only yield initial designs that need to be further tuned to boost the antenna performance. The major challenges include handling of multi-dimensional parameter spaces while accounting for several objectives and constraints. Due to complexity of modern antenna topologies, parameter interactions are often involved, leading to multiple local optima as well as difficulties in identifying decent initial designs that can be improved using local procedures. In such cases, global search is required, which is an expensive endeavor, especially if full-wave electromagnetic (EM) analysis is employed for antenna evaluation. This paper proposes a novel technique accommodating the search space exploration using local kriging surrogates and local improvement by means of trust-region gradient search. Computational efficiency of the process is achieved by constructing the metamodels over appropriately defined affine subspaces and incorporation of coarse-mesh EM simulations at the exploratory stages of the optimization process. The resulting framework enables nearly global search capabilities at the costs comparable to conventional gradient-based local optimization. This is demonstrated using two antenna examples and comparative studies involving multiple-start local tuning.
Expedited optimization of antenna input characteristics with adaptive Broyden updates
- Sławomir Kozieł
- Anna Pietrenko-Dąbrowska
2020 Full text ENGINEERING COMPUTATIONS
Simulation-driven adjustment of geometry and/or material parameters is a necessary step in the design of contemporary antenna structures. Due to their topological complexity, other means, such as supervised parameter sweeping, does not usually lead to satisfactory results. On the other hand, rigorous numerical optimization is computationally expensive due to a high cost of underlying full-wave electromagnetic (EM) analyses, otherwise required to assess antenna performance in a reliable manner. Design closure normally requires a local search, often carried out by means of gradient-based procedures. In this work, accelerated trust-region gradient-search algorithm is proposed for expedited optimization of antenna structures. In our approach, finite differentiation conventionally used to estimate the antenna response Jacobian is replaced, for selected variables, by a rank-one Broyden updating formula. The selection of variables is governed by the alignment between the direction of the recent design relocation and the coordinate system axes. Operation and performance of the algorithm is demonstrated using a set of benchmark wideband antennas. Comprehensive numerical validation indicates significant computational savings of up to 70 percent that can be achieved without compromising the design quality in a significant manner.
Expedited Yield Optimization of Narrow- and Multi-Band Antennas Using Performance-Driven Surrogates
- Anna Pietrenko-Dąbrowska
- Sławomir Kozieł
- Muath Al-hasan
2020 Full text IEEE Access
Uncertainty quantification is an important aspect of engineering design, also pertaining to the development and performance evaluation of antenna systems. Manufacturing tolerances as well as other types of uncertainties, related to material parameters (e.g., substrate permittivity) or operating conditions (e.g., bending) may affect the antenna characteristics. In the case of narrow- or multi-band antennas, this usually leads to frequency shifts of the operating bands. Quantifying these effects is imperative to adequately assess the design quality, either in terms of the statistical moments of the performance parameters or the yield. Reducing the antenna sensitivity to parameter deviations is even more essential when increasing the probability of the system satisfying the prescribed requirements is of concern. The prerequisite of such procedures is statistical analysis, normally carried out at the level of full-wave electromagnetic (EM) analysis. While necessary to ensure reliability, it entails considerable computational expenses, often prohibitive. Following the recently fostered concept of constrained modeling, this paper proposes a simple technique for rapid surrogate-assisted yield optimization of narrow- and multi-band antennas. The keystone of the approach is an appropriate definition of the optimization domain. This is realized by considering a few pre-optimized designs that represent the directions of the major changes of the antenna resonant frequencies and operating bands. Due to a small volume of such a domain, an accurate replacement model can be established therein using a small number of training samples, and employed to improve the antenna yield. Verification results obtained for a ring-slot antenna, a dual-band and a triple-band uniplanar dipoles indicate that the optimization process can be accomplished at low cost of a few dozen of EM simulations: 62, 74 and 132 EM simulations, respectively. Result reliability is validated through comparisons with EM-based Monte Carlo simulations.
Experience Based Clinical Decision Support Systems: An Overview and Case Studies
- Carlos Toro
- Manuel Grana
- Eider Sanchez
- Cesar Sanin
- Edward Szczerbicki
2020
This chapter briefly overviews the evolution of the application of the Decisional DNA and the Set of Experience Knowledge Structure (SOEKS) in the medical domain and in particular in the specific case of the experience-based decision support systems. Decisional DNA, as a knowledge representation structure, offers great possibilities on gathering explicit knowledge of formal decision events as well as a tool for decision making processes. The chapter collates more than 10 years of continuous application of the aforesaid techniques into the medical domain in particular for supporting the clinical decision scenario.
Experience-Based Cognition for Driving Behavioral Fingerprint Extraction
- Haoxi Zhang
- Fei Li
- Juan Wang
- Yang Zhou
- Cesar Sanin
- Edward Szczerbicki
2020 Full text CYBERNETICS AND SYSTEMS
ABSTRACT With the rapid progress of information technologies, cars have been made increasingly intelligent. This allows cars to act as cognitive agents, i.e., to acquire knowledge and understanding of the driving habits and behavioral characteristics of drivers (i.e., driving behavioral fingerprint) through experience. Such knowledge can be then reused to facilitate the interaction between a car and its driver, and to develop better and safer car controls. In this paper, we propose a novel approach to extract the driver’s driving behavioral fingerprints based on our conceptual framework Experience-Oriented Intelligent Things (EOIT). EOIT is a learning system that has the potential to enable Internet of Cognitive Things (IoCT) where knowledge can be extracted from experience, stored, evolved, shared, and reused aiming for cognition and thus intelligent functionality of things. By catching driving data, this approach helps cars to collect the driver’s pedal and steering operations and store them as experience; eventually, it uses obtained experience for the driver’s driving behavioral fingerprint extraction. The initial experimental implementation is presented in the paper to demonstrate our idea, and the test results show that it outperforms the Deep Learning approaches (i.e., deep fully connected neural networks and recurrent neural networks/Long Short-Term Memory networks).
Experimental analysis of wear resistance of compacts of fine-dispersed iron powder and tungsten monocarbide nanopowder produced by impulse pressing
- Anatoly Bragov
- Leonid Igumnov
- Alexander Konstantinov
- Andrey Lomunov
- Evgeny Rusin
- Victor Eremeev
2020 Full text WEAR
The paper presents the results of studying the structure and wear resistance of compacts produced from fine dispersed reduced iron powder (average particle size 3–mu m) with the addition of tungsten carbide (WC) nanopowder with the average particle size of 25–30 nm. The mass fraction of tungsten carbide (wolfram carbide) in the powder composition was 5% and 10% of the total mass. Impulse pressing was conducted using the modified Kolsky method at compacting temperatures of 20 °C to 300 °C. The produced compacts had relative density of over 90%.