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Gdańsk University of Technology

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Publications from the year 2021

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  • Study of Slip Effects in Reverse Roll Coating Process Using Non-Isothermal Couple Stress Fluid
    • Hasan Shahzad
    • Xinhua Wang
    • Muhammad Bilal Hafeez
    • Zahir Shah
    • Mohammed Ahmed Alsheri
    2021 Full text Coatings

    The non-isothermal couple stress fluid inside a reverse roll coating geometry is considered. The slip condition is considered at the surfaces of the rolls. To develop the flow equations, the mathematical modelling is performed using conservation of momentum, mass, and energy. The LAT (lubrication approximation theory) is employed to simplify the equations. The closed form solution for velocity, temperature, and pressure gradient is obtained. While the pressure and flow rate are obtained numerically. The impact of involved parameters on important physical quantities such as temperature, pressure, and pressure gradient are elaborated through graphs and in tabular form. The pressure and pressure gradient decreases for variation of the couple stress parameter and velocity ratio parameter K. While the variation of the slip parameter increases the pressure and pressure gradient inside the flow geometry. Additionally, flow rate decreases for the variation of the slip parameter as fluid starts moving rapidly along the roller surface. The most important physical quantity which is responsible for maintaining the quality of the coating and thickness is flow rate. For variation of both the couple stress parameter and the slip parameter, the flow rate decreases compared to the Newtonian case, consequently the coating thickness decreases for the variation of the discussed parameter

  • Study of Statistical Text Representation Methods for Performance Improvement of a Hierarchical Attention Network
    • Adam Wawrzyński
    • Julian Szymański
    2021 Full text Applied Sciences-Basel

    To effectively process textual data, many approaches have been proposed to create text representations. The transformation of a text into a form of numbers that can be computed using computers is crucial for further applications in downstream tasks such as document classification, document summarization, and so forth. In our work, we study the quality of text representations using statistical methods and compare them to approaches based on neural networks. We describe in detail nine different algorithms used for text representation and then we evaluate five diverse datasets: BBCSport, BBC, Ohsumed, 20Newsgroups, and Reuters. The selected statistical models include Bag of Words (BoW), Term Frequency-Inverse Document Frequency (TFIDF) weighting, Latent Semantic Analysis (LSA) and Latent Dirichlet Allocation (LDA). For the second group of deep neural networks, Partition-Smooth Inverse Frequency (P-SIF), Doc2Vec-Distributed Bag of Words Paragraph Vector (Doc2Vec-DBoW), Doc2Vec-Memory Model of Paragraph Vectors (Doc2Vec-DM), Hierarchical Attention Network (HAN) and Longformer were selected. The text representation methods were benchmarked in the document classification task and BoW and TFIDF models were used were used as a baseline. Based on the identified weaknesses of the HAN method, an improvement in the form of a Hierarchical Weighted Attention Network (HWAN) was proposed. The incorporation of statistical features into HAN latent representations improves or provides comparable results on four out of five datasets. The article presents how the length of the processed text affects the results of HAN and variants of HWAN models

  • Study of the Performance of DSSS UAC System Depending on the System Bandwidth and the Spreading Sequence
    • Iwona Kochańska
    • Roman Salamon
    • Jan Schmidt
    • Aleksander Schmidt
    2021 Full text SENSORS

    A signal transmitted in an Underwater Acoustic Communication (UAC) system operating in a shallow-water channel suffers from strong time dispersion due to multipath propagation. This causes the Inter-Symbol Interference (ISI) observed in the received signal, which significantly limits the communication system’s reliability and transmission rate. In such propagation conditions, the Direct-Sequence Spread Spectrum (DSSS) method is one of the solutions that make reliable data transmission possible. In systems with one-to-one communication, it ensures communication with a satisfactory Bit Error Rate (BER). Additionally, it makes it possible to implement the Code-Division Multiple Access (CDMA) protocol in underwater acoustic networks. This paper presents the results of simulation and experimental communication tests on a DSSS-based UAC system using three types of spreading sequence, namely m-sequences, Kasami codes and Gold codes, and occupying different bandwidths from 1 kHz to 8 kHz around a carrier frequency equal to 30 kHz. The UAC channel was simulated by impulse responses calculated by the virtual sources method and the UAC chanel models available in the Watermark simulator. The experimental tests were conducted in a model pool. Based on the obtained results, a transmission rate was estimated, which is possible to achieve in strong multipath propagation conditions, assuming reliability expressed as BER less than 0.001.

  • Study on CPU and RAM Resource Consumption of Mobile Devices using Streaming Services
    • Przemysław Falkowski-Gilski
    • Michał Woźniak
    2021

    Streaming multimedia services have become very popular in recent years, due to the development of wireless networks. With the growing number of mobile devices worldwide, service providers offer dedicated applications that allow to deliver on-demand audio and video content anytime and everywhere. The aim of this study was to compare different streaming services and investigate their impact on the CPU and RAM resources, with respect to type of Internet connection. The paper consists of two parts: theoretical and research. The first part provides a description of current means of wireless communication, including transmission of multimedia in Wi-Fi and cellular systems, as well as principles of operation of popular streaming media available on the marked, including utilized coding algorithm and available bitrates. The second part describes the set of utilized consumer devices, including 50 smartphones, as well as tools, laboratory equipment, and research scenarios. Results of this study may aid both researchers and professionals involved in the digital mobile market, including content and service providers, as well as network operators.

  • Study on Dry Sliding Wear and Friction Behaviour of Al7068/Si3N4/BN Hybrid Composites
    • Kumar Subramanian
    • Sakthivel Murugesan
    • Dhanesh G. Mohan
    • Jacek Tomków
    2021 Full text Materials

    Hybrid aluminium metal matrix composites have the potential to replace single reinforced aluminium metal matrix composites due to improved properties. Moreover, tribological performance is critical for these composites, as they have extensive application areas, such as the automotive, aerospace, marine and defence industries. The present work aims to establish the tribological characteristics of Al7068/Si3N4/BN hybrid metal matrix composites prepared by stir casting route and studied using a pin-on-disc apparatus under dry sliding conditions. The hybrid composite samples were prepared at various weight percentages (0, 5, 10) of Si3N4 and BN particles. To investigate the tribological performance of the prepared composites, the wear experiments were conducted by varying the load (20, 40 and 60 N), sliding velocity (1.5, 2.5 and 3.5 m/s) and sliding distance (500, 1000 and 1500 m). Wear experimental runs were carried out based on the plan of experiments proposed by Taguchi. The minimum wear rate was found with the composite material reinforced with 10 wt. % of Si3N4 and 5 wt. % of BN. Analysis of Variance (ANOVA) was employed to analyse the effect of process parameters on wear rate and coefficient of friction (COF). The ANOVA test revealed that the weight fraction of Si3N4 has more of a contribution percentage (36.60%) on wear rate, and load has more of a contribution percentage (29.73%) on COF. The worn-out surface of the wear test specimens was studied using its corresponding SEM micrograph and correlated with the dry sliding wear experiment results.

  • Study on Microstructural Characterization, Mechanical Properties and Residual Stress of GTAW Dissimilar Joints of P91 and P22 Steels
    • Anupam Sauraw
    • Atul Kumar Sharma
    • Dariusz Fydrych
    • Sachin Sirohi
    • Ankur Gupta
    • Aleksandra Świerczyńska
    • Chandan Pandey
    • Grzegorz Rogalski
    2021 Full text Materials

    This article deals with the dissimilar joining of two different grade Cr-Mo steel (2.25Cr-1Mo: P22 and modified 9Cr-1Mo: P91) for power plant application. The dissimilar butt-welded joint was produced for conventional V groove design by using the gas tungsten arc welding (GTAW) process with the application of an ERNiCrMo-3 Ni-based super alloy filler. A microstructure characterization was performed to measure the inhomogeneity in the microstructure and element diffusion across the interface in a welded joint. The experiments were also performed to evaluate the mechanical properties of the dissimilar welded joint in as-welded (AW) and post-weld heat treatment (PWHT) conditions. An acceptable level of the mechanical properties was obtained for the AW joint. After PWHT, a significant level of the element diffusion across the interface of the weld metal and P22 steel was observed, resulting in heterogeneity in microstructure near the interface, which was also supported by the hardness variation. Inhomogeneity in mechanical properties (impact strength and hardness) was measured across the weldments for the AW joint and was reduced after the PWHT. The tensile test results indicate an acceptable level of tensile properties for the welded joint in both AW and PWHT conditions and failure was noticed in the weak region of the P22 steel instead of the weld metal.

  • Study on Microstructure and Mechanical Properties of Laser Welded Dissimilar Joint of P91 Steel and INCOLOY 800HT Nickel Alloy
    • Vishwa Bhanu
    • Dariusz Fydrych
    • Ankur Gupta
    • Chandan Pandey
    2021 Full text Materials

    This investigation attempts to explore the weld characteristics of a laser welded dissimilar joint of ferritic/martensitic 9Cr-1Mo-V-Nb (P91) steel and Incoloy 800HT austenitic nickel alloy. This dissimilar joint is essential in power generating nuclear and thermal plants operating at 600–650 °C. In such critical operating conditions, it is essential for a dissimilar joint to preserve its characteristics and be free from any kind of defect. The difference between the physical properties of P91 and Incoloy 800HT makes their weldability challenging. Thus, the need for detailed characterization of this dissimilar weld arises. The present work intends to explore the usage of an unconventional welding process (i.e., laser beam welding) and its effect on the joint’s characteristics. The single-pass laser welding technique was employed to obtain maximum penetration through the keyhole mode. The welded joint morphology and mechanical properties were studied in as-welded (AW) and post-weld heat treatment (PWHT) conditions. The macro-optical examination shows the complete penetrations with no inclusion and porosities in the weld. The microstructural study was done in order to observe the precipitation and segregation of elements in dendritic and interface regions. Solidification cracks were observed in the weld fusion zone, confirming the susceptibility of Incoloy 800HT to such cracks due to a mismatch between the melting point and thermal conductivity of the base metals. Failure from base metal was observed in tensile test results of standard AW specimen with a yield stress of 265 MPa, and after PWHT, the value increased to 297 MPa. The peak hardness of 391 HV was observed in the P91 coarse grain heat-affected zone (CGHAZ), and PWHT confirmed the reduction in hardness. The impact toughness results that were obtained were inadequate, as the maximum value of impact toughness was obtained for AW P91 heat-affected zone (HAZ) 108 J and the minimum for PWHT Incoloy 800HT HAZ 45 J. Thus, difficulty in obtaining a dissimilar joint with Incoloy 800HT using the laser beam welding technique was observed due to its susceptibility to solidification cracking.

  • Study on Speech Transmission under Varying QoS Parameters in a OFDM Communication System
    • Monika Zamłyńska
    • Przemysław Falkowski-Gilski
    • Grzegorz Debita
    • Bogdan Miedziński
    2021

    Although there has been an outbreak of multiple multimedia platforms worldwide, speech communication is still the most essential and important type of service. With the spoken word we can exchange ideas, provide descriptive information, as well as aid to another person. As the amount of available bandwidth continues to shrink, researchers focus on novel types of transmission, based most often on multi-valued modulations, multiple channels and related sub-carriers. Currently, OFDM (Orthogonal Frequency Division Multiplexing) is widely utilized both in wired and wireless transmission. It includes terrestrial and online digital services, such as cellular systems and broadcasting standards. This paper is focused on varying QoS (Quality of Service) aspects, related with the OFDM telecommunication system, with respect to speech signals. It involves a group of four language sets, namely: American English, British English, German, and Polish. Results of this study may aid both researchers and professionals involved in designing everyday communication services as well as supplementary back-up services.

  • Study on Strategy in University Laboratory Class Teaching
    • Edward Szczerbicki
    • Haoxi Zhang
    2021 Full text

    Laboratory teaching is a critical way to ensure the effective input of techniques in engineering learning. Laboratory teaching not only contributes to improving course quality but also helps enrich comprehensive engineering application ability. However, there are some typical problems in current university laboratory teaching, such as rigid and isolated course design, outdated contents and materials, and not encouraging innovation and real-world problem solving. To overcome these challenges, a three-step teaching reconstruction strategy has been proposed to enhance university educators’ teaching effects, including introduce new laboratory teaching methods, updating contents and materials, and organizing innovative and multi-discipline Learning. Through efforts made by university teachers, students, and industry partners, the goal can be achieved by following the proposed strategy

  • Study on the Positioning Accuracy of GNSS/INS Systems Supported by DGPS and RTK Receivers for Hydrographic Surveys
    • Andrzej Stateczny
    • Cezary Specht
    • Mariusz Specht
    • David Brčić
    • Alen Jugović
    • Szymon Widźgowski
    • Marta Wiśniewska
    • Oktawia Lewicka
    2021 Full text ENERGIES

    Hydrographic surveys, in accordance with the International Hydrographic Organization (IHO) S-44 standard, can be carried out in the following five orders: Exclusive, Special, 1a, 1b and 2, for which minimum accuracy requirements for the applied positioning system have been set out. They are as follows, respectively: 1, 2, 5, 5 and 20 m, with a confidence level of 95% in twodimensional space. The Global Navigation Satellite System (GNSS) network solutions (accuracy: 2–3 cm (p = 0.95)) and the Differential Global Positioning System (DGPS) (accuracy: 1–2 m (p = 0.95)) are now commonly used positioning methods in hydrography. Due to the fact that a new order of hydrographic surveys has appeared in the IHO S-44 standard from 2020—Exclusive, looking at the current positioning accuracy of the DGPS system, it is not known whether it can be used in it. The aim of this article is to determine the usefulness of GNSS/Inertial Navigation Systems (INS) for hydrographic surveys. During the research, the following two INSs were used: Ekinox2-U and Ellipse- D by the SBG Systems, which were supported by DGPS and Real Time Kinematic (RTK) receivers. GNSS/INS measurements were carried out during the manoeuvring of the Autonomous/Unmanned Surface Vehicle (ASV/USV) named “HydroDron” on Kłodno lake in Zawory. The acquired data were processed using the mathematical model that allows us to assess whether any positioning system at a given point in time meets (or not) the accuracy requirements for each IHO order. The model was verified taking into account the historical and current test results of the DGPS and RTK systems. Tests have confirmed that the RTK system meets the requirements of all the IHO orders, even in situations where it is not functioning 100% properly. Moreover, it was proven that the DGPS system does not only meet the requirements provided for the most stringent IHO order, i.e., the Exclusive Order (horizontal position error 1 m (p = 0.95)). Statistical analyses showed that it was only a few centimetres away from meeting this criterion. Therefore, it can be expected that soon it will be used in all the IHO orders.

  • Study on the prevalence of mobile phone use by car drivers – the case of Poland
    • Paulina Szrywer
    • Joanna Wachnicka
    • Wojciech Kustra
    • Orazio Pellegrino
    2021 Full text Archives of Civil Engineering

    : Distracted driving is a significant factor affecting road safety and it can occur as a result of using mobile phones while driving. The aim of the current research is to present the prevalence of mobile phone use by Polish car drivers, based on the roadside and online survey. The field study showed that 11.6% of 1867 drivers were using mobile phones while being in motion and 26.1% of 203 drivers when stopped in front of traffic lights. While moving, 8.9% were manipulating the device by hand and 2.6% – holding it to ear. During the stop, 14.2% of the observed motorists were manipulating it, 3.0% – holding it to the ear, and 8.9% – talking through a hands-free or headset. To determine how many people generally use mobile phones while driving (not only during momentary observation), a questionnaire was also carried out. The vast majority of 252 surveyed drivers (82.9%) admitted to using mobile phones while driving, and an equally large proportion considered this behavior as dangerous for transport safety (81.3%). Most of the motorists reported using cell phones: rarely (44.4%), both when stopped and being in motion (58.9%), in a built-up area (63.6%), holding it in hand (43.5%) and in order to chat or write messages (81.8%). The majority of drivers using cell phones while driving were male and in the 25–44 or 18–24 age group. None of the respondents caused an accident due to the use of these devices, but 1.6% were guilty of a collision caused by this reason

  • STUDY ON THE RELATIONSHIP BETWEEN VEHICLE MAINTENANCE AND FUEL CONSUMPTION
    • Olha Sakno
    • Ievgen Medvediev
    • Tatiana Kolesnikova
    2021 Full text Zeszyty Naukowe Politechniki Śląskiej. Seria: Transport

    A contemporary road vehicle (RV) is a rather complex system, consisting of a large number of subsystems, assemblies, units, and elements (parts). While operating, an RV interacts with the environment, and its elements interact with each other. Consequently, the properties (parameters) of these elements change in the process - hardness, roughness, size, relative position, gapping, etc. A partial solution to the presented problems can be the search for a technique for assessing the RV technical condition by a generalised criterion, which is quite sensitive to changes in the technical state. One of these criteria may be fuel consumption in litres per 100 kilometres. This paper investigates the possibilities of using the fuel consumption indicator as a criterion for assessing the technical condition of the vehicle and the vehicle maintenance and repair technologies have been generalised to obtain a given technical solution. Thus, the possibility of using the fuel consumption indicator as a criterion for assessing the technical condition of the vehicles was explored using the Volkswagen Touran 1.9 TDI operating in urban conditions using a driving cycle. A clear correlation between the fuel consumption and the service lifetime of the vehicle has been established; therefore, it depends on the frequency and quality of the maintenance and repair (MR). The vehicle MR technology has been generalised to obtain a specified technical solution. The process of creating an RV MR Technology model is implemented based on an iterative approach (repetition) with the possibility to specify their features.

  • Subiektywny pomiar jakości sygnałów mowy i muzyki w lokalnych multipleksach radiofonii DAB+ w Gdańsku i Wrocławiu
    • Przemysław Falkowski-Gilski
    • Stefan Brachmański
    2021

    Radiofonia cyfrowa DAB+ (Digital Audio Broadcasting plus) dostępna jest dla słuchaczy w Polsce od 2013 r. Standard ten oferuje szerokie możliwości konfiguracji multipleksów lokalnych nie tylko pod względem liczby, lecz także jakości nadawanych programów radiowych. Dzięki temu możliwe jest dostosowanie parametrów emitowanych sygnałów w celu sprostania oczekiwaniom odbiorców końcowych. W przeciwieństwie do radiofonii analogowej FM sygnały audio pochodzące od różnych nadawców grupowane są w zbiór określany - ensemble. W pracy przedstawiono wyniki subiektywnych testów oceny jakości programów radiowych obejmujących sygnały mowy oraz muzyki. Badania przeprowadzono na lokalnych wariantach cyfrowego multipleksu dla Gdańska i Wrocławia. Opisano rezultaty ocen tych samych programów radiowych nadających jednakowy materiał dźwiękowy w technice analogowej FM i cyfrowej DAB+ (tzw. simulcast). Wyniki obejmowały zarówno pierwszy multipleks polskiego nadawcy (Gdańsk), jak i pionierski multipleks jednoczęstotliwościowy (Wrocław).

  • Sugar Fee in Poland as an Example of New Fiscal Burdens and Stimulation of Consumer Behaviour
    • Piotr Kasprzak
    2021

    During the economic downturn caused by the COVID-19 pandemic, the amount and structure of tax burdens imposed by the state on businesses continue to increase, as shown on the example of the newly introduced sugar fee. A new tax-related burden imposed on businesses and consumers producing and consuming sugar-sweetened beverages appeared at the beginning of 2021. The aim of the paper is to present the fiscal burdens that accompany the introduction of the sugar fee along with the justification for its introduction and its impact on the functioning of the sweetened beverage market.

  • Sulfate reducing ammonium oxidation (SULFAMMOX) process under anaerobic conditions
    • Dominika Grubba
    • Joanna Majtacz
    • Jacek Mąkinia
    2021 Full text Environmental Technology & Innovation

    Sulfate (SO42-) can be an electron acceptor for ammonium nitrogen (NH4+) oxidation under anaerobic conditions. The process is known as sulfammox and can be a viable alternative to conventional, nitrite (NO2-) dependent, anammox. Two bacterial species, including Bacillus Benzoevorans and Brocadia Anammoxoglobus Sulfate, can perform that process. With sulfammox, an economically inefficient pre-nitration step (due to aeration) is not required. There are more than 10 different systems in which sulfammox has been studied, including suspended growth, biofilm, granular and hybrid reactors. A combination of anammox and sulfur related processes (sulfammox and autotrophic denitrification) would especially be appropriate for specific industrial wastewater with high content of nitrogen compounds and SO42-. The results of recent studies suggest that very high removal efficiencies could simultaneously be achieved with respect to both NH4+ (92-99%) and SO42- (53-60%).

  • Sulfurization of phosphanylphosphinidene ligand: Access to phosphinothioyltrithiophosphonato platinum(II) complexes
    • Anna Ordyszewska
    • Natalia Szynkiewicz
    • Jarosław Chojnacki
    • Rafał Grubba
    • Jerzy Pikies
    2021 Full text INORGANICA CHIMICA ACTA

    The reactivity of phosphanylphosphinidene Pt(0) complexes [DppePt(η2-P–PtBu2)] (1) and [(pTol3P)2Pt(η2-P–PtBu2)] (2) toward sulfur was studied. Reactions of 1 and 2 with an excess of sulfur led to the formation of the first transition metal complexes 3 and 4 with phosphinothioyltrithiophosphonato ligands with the formula [tBu2P(=S)–P(=S)S2]2-. In contrast to previous reports on the phosphanylphosphinidene moiety sulfurization, the P–P bond was not cleaved during these reactions. The structures of sulfurization products 3 and 4 were elucidated using NMR spectroscopy, X-ray diffraction, and DFT calculations.

  • Sum-over-state expressions including second-order Herzberg–Teller effects for the calculation of absorption and resonance Raman intensities
    • Julien Guthmuller
    2021 Full text JOURNAL OF CHEMICAL PHYSICS

    The sum-over-state expressions are derived to calculate the second-order Herzberg–Teller (HT) effects in absorption and resonance Raman spectroscopies. These effects depend on the second derivatives of the transition dipole moment with respect to the vibrational coordinates. The method is applied to the molecule of 1,3-butadiene using density functional theory calculations. It is found that the second-order HT effects are significant for both absorption and resonance Raman intensities, and that the calculated spectra are in good agreement with the experimental data. The second-order HT effects originate from diagonal elements of the second derivatives matrix, whereas non-diagonal elements have a negligible impact on the intensities of 1,3-butadiene.

  • Superconductivity in LiGa2Ir Heusler type compound with VEC = 16
    • Karolina Górnicka
    • Gabriel Kuderowicz
    • Michał Winiarski
    • Bartłomiej Wiendlocha
    • Tomasz Klimczuk
    2021 Full text Scientific Reports

    Polycrystalline LiGa2Ir has been prepared by a solid state reaction method. A Rietveld refnement of powder x-ray difraction data confrms a previously reported Heusler-type crystal structure (space group Fm-3m, No. 225) with lattice parameter a= 6.0322(1) Å. The normal and superconducting state properties were studied by magnetic susceptibility, heat capacity, and electrical resistivity techniques. A bulk superconductivity with Tc= 2.94 K was confrmed by detailed heat capacity studies. The measurements indicate that LiGa2Ir is a weak-coupling type-II superconductor (e–p = 0.57, C/γTc= 1.4). Electronic structure, lattice dynamics, and the electron–phonon interaction are studied from frst principles calculations. Ir and two Ga atoms equally contribute to the Fermi surface with a minor contribution from Li. The phonon spectrum contains separated high frequency Li modes, which are seen clearly as an Einstein-like contribution in the specifc heat. The calculated electron–phonon coupling constant e–p = 0.68 confrms the electron–phonon mechanism for the superconductivity. LiGa2Ir and recently reported isoelectronic LiGa2Rh are the only two known representatives of the Heusler superconductors with the valence electron count VEC= 16.

  • Superconductivity in the Endohedral Ga Cluster Compound PdGa5
    • Zuzanna Ryżyńska
    • Piotr Wiśniewski
    • Dariusz Kaczorowski
    • Weiwei Xie
    • Robert J. Cava
    • Tomasz Klimczuk
    • Michał Winiarski
    2021 Full text Journal of Physical Chemistry C

    Superconductivity is observed below Tc = 1.6 K in an endohedral Ga cluster compound PdGa5 using magnetization and heat capacity measurements. Electronic structure calculations show that the density of states (DOS) at the Fermi level is dominated by Ga s and p states and that the overall shape of DOS is similar to what was found in other endohedral Ga cluster superconductors, such as MoxGa5x+1, ReGa5, and T2Ga9 (T = Rh and Ir). Our results provide a more complete picture of the relationship between the valence electron count and superconductivity in the family of endohedral Ga cluster superconductors.

  • SUPPORT FOR OLDER ADULTS DURING COVID19 PANDEMIC – HOW DID LOCAL AUTHORITIES IN THE POMERANIAN REGION RESPOND TO THE CHALLENGE?
    • Anita Richert-Kaźmierska
    2021

    The COVID-19 pandemic, apart from health threats, has shown the problem of older adults’ social isolation and loneliness in aging societies that has been progressing for several decades. Older adults’ singularisation, loosening family relations, diminishing families’ caring potential, caused that during the lockdown, many older adults – without the neighbours’ or NGOs’ support or the activities undertaken by local authorities – would be left without meeting their basic life and social needs. Authors draw their attention to the different aspects of population aging process and its socio-economic consequences. Nevertheless, the subject of older adults’ loneliness and the growing role of institutions (coordinated by local government authorities) in providing them different care services still seems insufficiently researched in the Polish-language literature. In Polish society, citizens prefer that the informal care needs of older adults are assiduously met by family members. However, the months of the COVID-19 pandemic lockdown have clearly shown that this traditional model of informal care is not always possible in practice, and that family members are increasingly turning to regional local authorities to assist them in the care requirements of older and frail relatives. Many family members are not always ready to provide care for older relatives at home due to a lack of appropriate knowledge and assistive aids.