2021 - Publications Repository - Gdańsk University of Technology

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Publications from the year 2021

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Design Evolution of the Ultrasonic Piezoelectric Motor Using Three Rotating Mode Actuators
- Roland Ryndzionek
- Łukasz Sienkiewicz
- Michał Michna
- Marek Chodnicki
2021 Full text IEEE Access
The development process and experimental investigation of the multicell piezoelectric motor is presented in this paper. The proposed design consists of three individual cells integrated into the stator, double rotor, and a preload system. Those elements are combined into a symmetrical structure of the motor. The two new prototypes have been designed, simulated and tested. Finite element numerical analysis is carried out to obtain optimal dimensions of the individual cell in terms of generated vibrations and resonant frequencies of the structure. The results of the numerical analysis are compared with analytical calculations based on the equivalent circuit model. The stator of the motor was manufactured using a three-dimensional (3-D) printer using alumide material. Finally, the experimental tests were conducted and presented. Analytical, numerical and experimental results are in satisfactory agreement. Two new prototypes of the multicell piezoelectric motor exhibit torque-speed characteristics similar to the original while being cheaper and easier to manufacture.
Design of a compact planar transmission line for miniaturized rat-race coupler with harmonics suppression
- Ali Lalbakhsh
- Golshan Mohamadpour
- Saeed Roshani
- Mohammad Ami
- Sobhan Roshani
- Abu Sadat Sayem
- Mohammad Alibakhshikenari
- Sławomir Kozieł
2021 Full text IEEE Access
This paper presents an elegant yet straightforward design procedure for a compact rat-race coupler (RRC) with an extended harmonic suppression. The coupler’s conventional λ/4 transmission lines (TLs) are replaced by a specialized TL that offers significant size reduction and harmonic elimination capabilities in the proposed approach. The design procedure is verified through the theoretical, circuit, and electromagnetic (EM) analyses, showing excellent agreement among different analyses and the measured results. The circuit and EM results show that the proposed TL replicates the same frequency behaviour of the conventional one at the design frequency of 1.8 GHz while enables harmonic suppression up to the 7th harmonic and a size reduction of 74%. According to the measured results, the RRC has a fractional bandwidth of 20%, with input insertion losses of around 0.2 dB and isolation level better than 35 dB. Furthermore, the total footprint of the proposed RRC is only 31.7 mm × 15.9 mm, corresponding to 0.28 λ × 0.14 λ, where λ is the guided wavelength at 1.8 GHz.
Design of a Patch Power Divider with Simple Structure and Ultra-Broadband Harmonics Suppression
- Saeed Roshani
- Sławomir Kozieł
- Sobhan Roshani
- Mohammad Jamshidi
- Fariborz Parandin
- Stanisław Szczepański
2021 Full text IEEE Access
This paper introduces a simple H-shaped patch Wilkinson power divider (WPD), which provides ultra wide harmonics suppression band. The presented WPD designed at 1.8 GHz, and exhibits good performance at the operating bandwidth. In the proposed divider structure, two simple patch low-pass filters (LPFs) are employed at each branch, and three open ended stubs are added at each port. The proposed divider, implemented using the aforementioned structures has a good performance at both higher frequencies, and the operating frequency. In particular, the designed divider provides an ultra wide suppression band from 3 GHz to 20 GHz, which encompasses the 2nd up to the 11th harmonic. The proposed WPD has an operating band from 1.62 GHz to 2.1 GHz, with the operating bandwidth exceeding 480 MHz. Consequently, the fractional bandwidth (FBW) of 25.8 percent is obtained. The results indicate |S11|, |S12|, |S22|, and |S23|, are equal to –17 dB, –3.5 dB, –20 dB, and –17 dB, respectively, at the operating frequency. The simulation results are corroborated through the measurements of the fabricated divider prototype. The superior harmonic suppression capability is also demonstrated through comparisons with state-of-the-art divider circuits from the literature.
Design of experiments approach for ultimate strength assessment of corroded stiffened plates
- Krzysztof Wołoszyk
- Yordan Garbatov
2021 Full text
The impact of corrosion degradation on the ultimate strength of stiffened plates subjected to compressive loading is investigated. The DoE technique is used considering different plate and column slenderness ratios and corrosion severity. The FE method, considering geometrical and material nonlinearities, is employed. A two-stage corrosion degradation model is adopted. Firstly, a uniform thickness loss is adopted to reflect the mean loss of the volume of material. Secondly, mechanical properties are reduced, to reflect the local non-uniformity of the corroded surface, leading to a local strain reduction when compared to a smooth surface plate. As an analysis outcome, the most important governing factors and interactions between them are obtained. The post-collapse shapes are presented and discussed. The resulting structural response surface allows for fast estimation of the ulti-mate strength of corroded stiffened plate, revealing to be a swift and practical tool to be adopted in the engineering practice.
Design of High-Performance Scattering Metasurfaces through Optimization-Based Explicit RCS Reduction
- Sławomir Kozieł
- Muhammad Abdullah
- Stanisław Szczepański
2021 Full text IEEE Access
The recent advances in the development of coding metasurfaces created new opportunities in realization of radar cross section (RCS) reduction. Metasurfaces, composed of optimized geometries of meta-atoms arranged as periodic lattices, are devised to obtain desired electromagnetic (EM) scattering characteristics. Despite potential benefits, their rigorous design methodologies are still lacking, especially in the context of controlling the EM wavefront through parameter tuning of meta-atoms. One of the practical obstacles hindering efficient design of metasurfaces is implicit handling of RCS performance. To achieve essential RCS reduction, the design task is normally formulated in terms of phase reflection characteristics of the meta-atoms, whereas their reflection amplitudes—although contributing to the overall performance of the structure—is largely ignored. As a result, the conventional approaches are unable to determine truly optimum solutions. This article proposes a novel formulation of the metasurface design task with explicit handling of RCS reduction at the level of meta-atoms. Our methodology accounts for both the phase and reflection amplitudes of the unit cells. The design objective is defined to directly optimize the RCS reduction bandwidth at the specified level (e.g., 10 dB) w.r.t. the metallic surface. The benefits of the presented scheme are twofold: (i) it provides a reliable insight into the metasurface properties even though the design process is carried out at the level of meta-atoms, (ii) the obtained design requires minimum amount of tuning at the level of the entire metasurface. None of these is possible for phase-response-based approach fostered in the literature. For practical purposes, the design is conducted using a surrogate-assisted procedure involving kriging metamodels, which enables global optimization at a low computational cost. To corroborate the utility of our formulation, a high-performance metasurface incorporating crusader-cross-shaped meta-atoms has been developed. The obtained results indicate that the system characteristics predicted at the design stage are well aligned with those of the EM-simulated structure (which is not the case for the traditional design approach). The metasurface features 10-dB RCS reduction in the frequency range of 16.5 GHz to 34.6 GHz, as validated both numerically and experimentally.
Design of Intelligent Low-Voltage Load Switch for Remote Control System in Smart Grid
- Dezhi Xiong
- Xiangqun Chen
- Radek Martinek
- He Wen
- Derong Luo
- Janusz Smulko
2021 Full text Iranian Journal of Science and Technology-Transactions of Electrical Engineering
Current low-voltage load switches do not support remote disconnect/connect and real-time monitoring of a disconnect/connect state. Addressing to these issues, this paper presents a low-voltage load switch for a smart remote control system, which uses a one-chip microcontroller board and a DC step motor drive mechanism and provides the feedback on the switch status also. Arrears disconnect and full-pay connect control is implemented via the microcomputer and Hall sensor. The low-power supply and state feedback circuit are designed to reduce the power consumption. And the motor drive mechanism is optimized to improve the performance of motor. Finally, a test environment includes the system control and feedback is created to illustrate the feasibility of the designed low-voltage switch. The test results that the design supports disconnect/connect control and state feedback in various conditions validate the feasibility of this designed system, which has high practical value and is worthy of promotion.
Design of weighted PID controllers for control of the Stewart-Gough platform
- Justyna Kolasiewicz
- Anna Perżyło
- Robert Piotrowski
2021
Stewart-Gough platform (SGP) is a popular parallel type manipulator that involves a 6 degrees of freedom (DOF) motion. In this paper, the process of mathematical modelling of SGP is presented. Two selected control algorithms that use PID controllers and weighted PID controllers are designed. Both control systems using these algorithms are implemented in MATLAB environment as well as on the actual SGP. Parameters of the controllers are optimized with the use of different integral performance criteria. Tests of the designed control systems on the computer model and on the SGP are presented.
Design principles for creating digital transparency in government
- Ricardo Matheus
- Marijn Janssen
- Tomasz Janowski
2021 Full text GOVERNMENT INFORMATION QUARTERLY
Under pressure to fight corruption, hold public officials accountable, and build trust with citizens, many governments pursue the quest for greater transparency. They publish data about their internal operations, externalize decision-making processes, establish digital inquiry lines to public officials, and employ other forms of transparency using digital means. Despite the presence of many transparency-enhancing digital tools, putting such tools together to achieve the desired level of digital transparency, to design entire government systems for digital transparency, remains challenging. Design principles and other design guides are lacking in this area. This article aims to fill this gap. We identify a set of barriers to digital transparency in government, define 16 design principles to overcome such barriers, and evaluate these principles using three case studies from different countries. Some principles apply to projects, others to systems, yet others to entire organizations. To achieve digital transparency, before building and deploying digital solutions, government organizations should build technological and institutional foundations and use such foundations to organize themselves for transparency. The proposed design principles can help develop and apply such foundations.
Designing acoustic scattering elements using machine learning methods
- Adam Kurowski
2021 Full text
In the process of the design and correction of room acoustic properties, it is often necessary to select the appropriate type of acoustic treatment devices and make decisions regarding their size, geometry, and location of the devices inside the room under the treatment process. The goal of this doctoral dissertation is to develop and validate a mathematical model that allows predicting the effects of the application of the scattering system in selected points of the room. Further, it is aimed to use this model in the process of computer optimization of the room sound treatment process. The means for achieving these goals are machine learning algorithms with a particular focus on deep learning and reinforcement learning. Deep machine learning models are trained by using computer simulation employing the finite difference method (FDTD), which is used as a source of the reward signal. The simulation model is based on the modified difference equations derived by the author of this thesis that allows simulating the behavior of acoustic diffusers in anechoic conditions. In order to reproduce this type of conditions, the results obtained by the reinforcement learning algorithms, in particular - by the deep policy gradient algorithm, were compared with the results obtained with the classical methods of designing acoustic diffusers and those obtained using another optimization method, i.e., genetic algorithms, where the numerical simulation of the behavior of the acoustic diffuser serves to calculate the value of the fitness function, which plays a role analogous to the reward function. The optimized property of acoustic diffusers is the autocorrelation diffusion coefficient. Numerical experiments have shown that optimization algorithms can be used to maximize the metrics computed by numerical simulation. The best results were obtained with the reinforcement learning algorithms. To validate the calculation results, the measurement of acoustic diffuser prototypes was also performed in the anechoic chamber. As a result of the measurements, the thesis confirmed that the algorithms resulting from computer optimization are characterized by more desirable parameters - the broadband autocorrelation diffusion coefficient and the band diffusion coefficients calculated for the bands with central frequencies with the values from 250 Hz up to 4 kHz. The proposed algorithm is a new approach to the intelligent design of acoustic systems to improve room acoustic properties.
Designing Control and Protection Systems with Regard to Integrated Functional Safety and Cybersecurity Aspects
- Marcin Śliwiński
- Emilian Piesik
2021 Full text ENERGIES
This article addresses current problems of risk analysis and probabilistic modelling for functional safety management in the life cycle of safety-related systems. Two main stages in the lifecycle of these systems are distinguished, namely the design and operation. The risk analysis and probabilistic modelling differ in these stages in view of available knowledge and data. Due to the complexity and uncertainty involved, both qualitative and quantitative information can be useful in risk analysis and probabilistic modelling. Some methodological aspects of the functional safety assessment are outlined that include mod-elling of dependent failures or cybersecurity and verifying the safety integrity level (SIL) under uncertainty. It is illustrated how the assumptions in the process of risk analysis and probabilistic modelling influence results obtained and, therefore, potentially the decisions taken in functional safety management. Programmable control and safety systems play an important role in mitigating and controlling risks in the operation of hazardous installa-tions. This paper presents ways to deal with safety hazards involving such systems to be considered in risk analysis and integrated functional safety and cybersecurity manage-ment.
Designing with Green and Blue – Climate Adaption Proposals for Lowland Areas of Gdańsk
- Lucyna Nyka
- Rui Simões
- Pedro Ressano Garcia
- Joanna Rayss
2021
The paper gives insight into issues explored within the framework of the SOS Climate Waterfront workshop that took place in Gdańsk in June 2019. The aim of the study was to propose solutions that will decrease the number of flooding events and span the gap between flood prevention strategies and the provision of other benefits such as ecological, urban, cultural and social. Historical cartography enquiries and research by the design method were used to develop design concepts. The main foundation for the design concept was built on the goal of providing more room for water, particularly for stormwater and rainwater. The second aim was to create blue-green connections that would span the amorphous territory and bring various benefits, including environmental, hydrological, and social. As research studies demonstrate, historical hydrographies can be effectively explored as guiding agents in urban climate adaptation schemes. Referring to past landscapes contributes not only to the protection but also to the exposition of cultural heritage and strengthening the relations between historical buildings and urban surroundings. It conduces to questioning the land-water dichotomy in favour of proposing their alternative and more fluid boundaries making territories less vulnerable to the threats brought by climate disasters.
Detecting Apples in the Wild: Potential for Harvest Quantity Estimation
- Artur Janowski
- Rafał Kaźmierczak
- Cezary Kowalczyk
- Jakub Szulwic
2021 Full text Sustainability
Knowing the exact number of fruits and trees helps farmers to make better decisions in their orchard production management. The current practice of crop estimation practice often involves manual counting of fruits (before harvesting), which is an extremely time-consuming and costly process. Additionally, this is not practicable for large orchards. Thanks to the changes that have taken place in recent years in the field of image analysis methods and computational performance, it is possible to create solutions for automatic fruit counting based on registered digital images. The pilot study aims to confirm the state of knowledge in the use of three methods (You Only Look Once—YOLO, Viola–Jones—a method based on the synergy of morphological operations of digital imagesand Hough transformation) of image recognition for apple detecting and counting. The study compared the results of three image analysis methods that can be used for counting apple fruits. They were validated, and their results allowed the recommendation of a method based on the YOLO algorithm for the proposed solution. It was based on the use of mass accessible devices (smartphones equipped with a camera with the required accuracy of image acquisition and accurate Global Navigation Satellite System (GNSS) positioning) for orchard owners to count growing apples. In our pilot study, three methods of counting apples were tested to create an automatic system for estimating apple yields in orchards. The test orchard is located at the University of Warmia and Mazury in Olsztyn. The tests were carried out on four trees located in different parts of the orchard. For the tests used, the dataset contained 1102 apple images and 3800 background images without fruits.
Detection and Direction-of-Arrival Estimation of Weak Spread Spectrum Signals Received with Antenna Array
- Jarosław Magiera
2021 Full text Electronics
This paper presents a method for the joint detection and direction of arrival (DOA) estimation of low probability of detection (LPD) signals. The proposed approach is based on using the antenna array to receive spread-spectrum signals hidden below the noise floor. Array processing exploits the spatial correlation between phase-delayed copies of the signal and allows us to evaluate the parameter used to make the decision about the presence of LPD transmission. The DOA estimation is based on the covariance between signals received by sensors for the fixed geometry of the antenna array. Moreover, the paper provides a method for mitigating narrowband interferences prior to signal detection. The presented methods were verified through simulations which proved that the confident detection of a one-second transmission in an additive white Gaussian noise channel is possible even when the noise is 24 dB higher than the power of the received signal. The performance of DOA estimation is analyzed in a wide range of signal-to-noise and interference-to-noise ratios. It is found that the DOA may be estimated with an RMS error not exceeding 10 degrees, even if interference occupies 15% of the analyzed frequency band.
Detection and Model of Thermal Traces Left after Aggressive Behavior of Laboratory Rodents
- Magdalena Mazur-Milecka
- Jacek Rumiński
- Wojciech Glac
- Natalia Głowacka
2021 Full text Applied Sciences-Basel
Automation of complex social behavior analysis of experimental animals would allow for faster, more accurate and reliable research results in many biological, pharmacological, and medical fields. However, there are behaviors that are not only difficult to detect for the computer, but also for the human observer. Here, we present an analysis of the method for identifying aggressive behavior in thermal images by detecting traces of saliva left on the animals’ fur after a bite, nape attack, or grooming. We have checked the detection capabilities using simulations of social test conditions inspired by real observations and measurements. Detection of simulated traces different in size and temperature on single original frame revealed the dependence of the parameters of commonly used corner detectors (R score, ranking) on the parameters of the traces. We have also simulated temperature of saliva changes in time and proved that the detection time does not affect the correctness of the approximation of the observed process. Furthermore, tracking the dynamics of temperature changes of these traces allows to conclude about the exact moment of the aggressive action. In conclusion, the proposed algorithm together with thermal imaging provides additional data necessary to automate the analysis of social behavior in rodents.
DETECTION OF BREATHING AND HEART RATE USING AN ECG SIGNAL MEASURED WHILE BATHING IN THE BATHTUB
- Kamil Osiński
- Adam Bujnowski
- Jerzy Wtorek
- Oliwia Andrejko
2021
Nowadays a new area of interest is gaining importance - it is home biomedical examination. Intelligent home can be supported by set of devices for habitants observation. It can be particularly useful for elders or person with some health risks but living alone. One of critical locations within the house is bathroom. One of utilities in the bathroom is a bathtub which is sometimes preferred over shower. There are reports of problems during bath such as mobility problem when leaving bathtub or even sudden death cases.
Detection of Lexical Stress Errors in Non-Native (L2) English with Data Augmentation and Attention
- Daniel Korzekwa
- Roberto Barra-Chicote
- Szymon Zaporowski
- Grzegorz Beringer
- Jaime Lorenzo-trueba
- Alicja Serafinowicz
- Jasha Droppo
- Thomas Drugman
- Bożena Kostek
2021 Full text
This paper describes two novel complementary techniques that improve the detection of lexical stress errors in non-native (L2) English speech: attention-based feature extraction and data augmentation based on Neural Text-To-Speech (TTS). In a classical approach, audio features are usually extracted from fixed regions of speech such as the syllable nucleus. We propose an attention-based deep learning model that automatically de rives optimal syllable-level representation from frame-level and phoneme-level audio features. Training this model is challenging because of the limited amount of incorrect stress patterns. To solve this problem, we propose to augment the training set with incorrectly stressed words generated with Neural TTS. Combining both techniques achieves 94.8% precision and 49.2% recall for the detection of incorrectly stressed words in L2 English speech of Slavic and Baltic speakers.
Detection of petroleum products using optical coherence tomography
- Aleksandra Kamińska
- Jerzy Pluciński
2021 Full text Zeszyty Naukowe Wydziału Elektrotechniki i Automatyki Politechniki Gdańskiej
In this work, we present a novel method developed for the analysis of the properties of thin layers for detecting petroleum products on a water surface using a commercially available optical coherence tomography (OCT) system. The spectral density analysis of the signal from a spectroscopic OCT (S-OCT) enables us to perform the precision calculation of the thin layer thickness and other properties like homogeneity, and dispersion, even if layer thickness is smaller than the coherence length of light from the used broadband light source. Mathematical modeling has been confirmed by measurements. The experiment with thin oil films on the surface of the water was conducted. The obtained results indicate that it is possible to measure the thickness of the petroleum product layers on the surface of the water smaller than 1 μm with 10 nm resolution.
Deterioration and Protection of Concrete Elements Embedded in Contaminated Soil: A Review
- Ginneth Patricia Millán Ramírez
- Hubert Byliński
- Maciej Niedostatkiewicz
2021 Full text Materials
Coating materials are considered one of the most antique materials of human civilization; they have been used for decoration and the protection of surfaces for millennia. Concrete structures—due to their permanent exposure to different types of environments and contaminants—require the use of coatings that contribute to its preservation by reducing the corrosion of its components (steel and aggregates). This article intends to introduce the principal causes of concrete deterioration and the coating materials used to protect concrete structures, including a summary of the coating types, their advantages and disadvantages, and the latest developments and applications. Furthermore, this paper also assesses brief information about the potential challenges in the production of eco-friendly coating materials.
Determinants of COVID-19 Impact on the Private Sector: A Multi-Country Analysis Based on Survey Data
- Magdalena Olczyk
- Marta Kuc-Czarnecka
2021 Full text ENERGIES
Our paper aims to investigate the impact of COVID‐19 on private sector companies in terms of sales, production, finance and employment. We check whether the country and industry in which companies operate, government financial support and loan access matter to the behaviour and performances of companies during the pandemic. We use a microdata set from a worldwide survey of more than 15,729 companies conducted between April and September 2020 by the World Bank. Logistic regression is used to assess which factors increase the likelihood of businesses suffering due to the COVID‐19 pandemic. Our results show that COVID‐19 negatively impacts the performance of companies in almost all countries analysed, but a stronger effect is observed among firms from developing countries. The pandemic is more harmful to firms providing services than those representing the manufacturing sector. Due to the pandemic, firms suffer mainly in sales and liquidity decrease rather than employment reduction. The increase in the number of temporary workers is an important factor that significantly reduces the probability of sales, exports or supply decline. The analysis results indicate policy tools supporting enterprises during the pandemic, such as increasing the flexibility of the labour market or directing aid to developing countries.
Determinants of the primary stability of cementless acetabular cup implants: A 3D finite element study
- Katharina Immel
- Vu–Hieu Nguyen
- Arnaud Dubory
- Charles-Henri Flouzat-Lachaniette
- Roger Sauer
- Guillaume Haiat
2021 Full text COMPUTERS IN BIOLOGY AND MEDICINE
Primary stability of cementless implants is crucial for the surgical success and long–term stability. However, primary stability is difficult to quantify in vivo and the biomechanical phenomena occurring during the press–fit insertion of an acetabular cup (AC) implant are still poorly understood. The aim of this study is to investigate the influence of the cortical and trabecular bone Young's moduli Ec and Et, the interference fit IF and the sliding friction coefficient of the bone–implant interface μ on the primary stability of an AC implant. For each parameter combination, the insertion of the AC implant into the hip cavity and consequent pull–out are simulated with a 3D finite element model of a human hemi–pelvis. The primary stability is assessed by determining the polar gap and the maximum pull–out force. The polar gap increases along with all considered parameters. The pull–out force shows a continuous increase with Ec and Et and a non-linear variation as a function of μ and IF is obtained. For μ > 0.6 and IF > 1.4mm the primary stability decreases, and a combination of smaller μ and IF lead to a better fixation. Based on the patient's bone stiffness, optimal combinations of μ and IF can be identified. The results are in good qualitative agreement with previous studies and provide a better understanding of the determinants of the AC implant primary stability. They suggest a guideline for the optimal choice of implant surface roughness and IF based on the patient's bone quality.