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Gdańsk University of Technology

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  • Novel Tools as New Challenges to HRM Communicational Practices (and the Increasingly Important Social Role of the Manager)
    • Marta Szeluga-Romańska
    • Anna Modzelewska
    2022 Full text

    Each communicational process consists inseparably of three aspects: the linguistic (which means the whole language content of the message), technical (which states the form of the message) and the social (meaning social relations, emotions, behaviours). The recent COVID-19 pandemic deeply influenced several layers of our lives. But the main aim of this chapter is to focus on the communicational processes that normally take place in organisations. We conducted a qualitative study based mostly on in-depth interviews and observations among managers and management students. The analysis revealed the enormous expansion of technical dimensions of communication, where personal direct communication was often replaced by indirect ones, supported by the usage of modern tools like internet communicators and interactive software. This resulted in abnormal reduction of the social – highly needed and obviously important – dimension. Such ‘new normal’ organisational reality forced the HR managers to re-think the flow and quality of existing communicational processes within which they are always situated, also considering its deep, multidimensional influence on the existing social relations. This chapter presents the results of qualitative studies from in-depth interviews, structured interviews and focus group interviews from 2012 to 2020. We aim to answer the question of the changes which were brought into organisations by the pandemic as our long-term research allows to follow the changes. As a result, we received characteristics of the organisational changes and the shift in expectation from the role of a manager in the altered social reality. Practical implications are included in this chapter and provide guidelines for communication in crisis situations while maintaining a high quality of interpersonal relations.

  • Novel Vision Monitoring Method Based on Multi Light Points for Space-Time Analysis of Overhead Contact Line Displacements
    • Andrzej Wilk
    • Len Gelman
    • Jacek Skibicki
    • Sławomir Judek
    • Krzysztof Karwowski
    • Aleksander Jakubowski
    • Paweł Kaczmarek
    2022 Full text SENSORS

    The article presents an innovative vision monitoring method of overhead contact line (OCL) displacement, which utilizes a set of LED light points installed along it. A light point is an, LED fed from a battery. Displacements of the LED points, recorded by a camera, are interpreted as a change of OCL shape in time and space. The vision system comprises a camera, properly situated with respect to the OCL, which is capable of capturing a dozen light points in its field of view. The monitoring system can be scaled by increasing the number of LED points and video cameras; thus, this method can be used for monitoring the motion of other large–size objects (e.g., several hundred meters). The applied method has made it possible to obtain the following novel results: vibration damping in a contact wire is nonlinear by nature and its intensity depends on the wire vibration amplitude; the natural frequency of contact wire vibration varies, and it is a function of vibration amplitude; the natural frequency of contact wire vibration also depends on the wire temperature. The proposed method can be used to monitor the uplift of contact and messenger wires in laboratory conditions, or for experimental OCL testing, as well as for verifying simulation models of OCL.

  • Nowe potrójne związki w układzie RE2TGe3 (RE – ziemia rzadka, T – metal przejściowy)
    • Leszek Litzbarski
    2022 Full text

    Celem niniejszej pracy była synteza nowych związków międzymetalicznych z rodziny RE2TGe3, gdzie RE to metale ziem rzadkich, a T to metal przejściowy (Pd, Pt). Dokonano tego stosując metodę topienia w łuku elektrycznym. Za pomocą proszkowej dyfrakcji rentgenowskiej ustalono, że udało się otrzymać następujące materiały: Pr2Pd1.15Ge2.85, Sm2PdGe3, Tb2Pd1.25Ge2.85, Dy2Pd1.25Ge2.85, Ho2Pd1.3Ge2.7, Ce2Pt0.9Ge3.1, Pr2Pt1.15Ge2.85, Nd2PtGe3, Gd2Pt1.1Ge2.9, Tb2Pt1.2Ge2.8, Dy2Pt1.15Ge2.85 i Ho2Pt1.1Ge2.9. Aby uzyskać jednofazowe próbki należało w większości przypadków odejść od znamionowej stechiometrii i odpowiednio zmienić stosunek atomów T i Ge. W oparciu o analizę Rietvelda stwierdzono, iż związki te krystalizują w heksagonalnej strukturze o grupie przestrzennej P6/mmm. Obliczone wartości stałych sieci pokazują, że objętość komórki elementarnej maleje wraz ze wzrostem liczby atomowej RE, co jest zgodne z regułą tzw. „kontrakcji lantanowców”. Następnie scharakteryzowano własności fizyczne zsyntezowanych materiałów poprzez pomiary namagnesowania, oporu elektrycznego oraz ciepła właściwego. Na tej podstawie stwierdzono, że zbadane próbki można zaklasyfikować jako szkła klastrowe. Wyjątek stanowią Pr2Pt1.15Ge2.85 i Ho2Pt1.1Ge2.9, w których nie występuje uporządkowanie magnetyczne w zmierzonym zakresie temperatur (T = 1.8 – 300 K) oraz Gd2Pt1.1Ge2.9 zaliczający się do antyferromagnetyków.

  • Nowy system monitoringu korozji zastosowany w zakładzie produkcyjnym PKN Orlen SA
    • Radosław Gospoś
    • Anna Plis
    • Iwona Łuksa
    • Kazimierz Darowicki
    • Juliusz Orlikowski
    2022 Chemia Przemysłowa

    Przedstawiono efekty projektu badawczo-rozwojowego związanego z opracowaniem, budową oraz wdrożeniem monitoringu korozji pracującego w trybie online. Opracowana przez PKN Orlen i Politechnikę Gdańską nowa technologia łączy funkcje monitoringu intensywności korozji ogólnej oraz kruchości wodorowej. Jednoczesny pomiar online kluczowych parametrów pozwala uzyskać zdolność szybkiej oceny postępowania procesu korozji oraz reakcji na bieżące wahania poziomu zagrożenia.

  • NOx Photooxidation over Different Noble Metals Modified TiO2
    • Kinga Skalska
    • Anna Malankowska
    • Jacek Balcerzak
    • Maria Gazda
    • Grzegorz Nowaczyk
    • Stefan Jurga
    • Adriana Zaleska-Medynska
    2022 Full text Catalysts

    We compared the activity enhancement effect of noble metal deposited on TiO2 in photocatalytic nitrogen oxides oxidation. Titanium dioxide was decorated with Ag, Au, Pt or Pd in the sol-gel process. Synthesized catalysts were characterized by X-ray diffraction (XRD), Brunauer–Emmett–Teller measurement (BET), X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM) and energy dispersive X-ray analysis (EDX). All catalysts together with pure TiO2 obtained by sol-gel (SG) technique were tested for their photocatalytic activity towards nitrogen oxide oxidation (high concentrations of 50, 150 and 250 ppm). FTIR spectrometry was used to determine the gas phase composition and identify TiO2 surface species. The Ag0.1 sample turned out to be deactivated within 60 min of UV/Vis irradiation. Photocatalytic oxidation rate towards NO2 turned to be the highest over SG (photocatalyst without metal deposition). NO2 formation was also observed for Au0.1, Au0.5, Pt0.1, Pt0.5 and Pd0.1. The best NOx removal, i.e., conversion to final product HNO3 was obtained with the Au0.5 photocatalyst.

  • Numbers, Please: Power- and Voltage-Related Indices in Control of a Turbine-Generator Set
    • Paweł Sokólski
    • Tomasz Rutkowski
    • Bartosz Ceran
    • Daria Złotecka
    • Dariusz Horla
    2022 Full text ENERGIES

    This paper discusses the proper selection and interpretation of aggregated control performance indices values mirroring the quality of electrical energy generation by a turbine-generator set cooperating with a power system. Typically, a set of basic/classical and individual indices is used in energy engineering to ensure the mirroring feature and is related to voltage, frequency and active or reactive power deviations from their nominal values desired in the power system. In this paper, aggregated indices based on the sum of weighted integral indices are proposed, verified and built based on the well-known indices originating from control theory. These include an integral of the squared error (ISE) and an integral of the squared error multiplied by time (ITSE), applicable whenever an in-depth analysis and evaluation of various control strategies of the generation system is to be performed. In the reported research, the computer simulation tests verified their effectiveness in assessing the generated electricity on the example of a turbine-generator set controlled using a predictive control technology as well as applicability, proven by numerous simulation results to take various and different in nature requirements into account efficiently, in the form of a single aggregated index.

  • Numerical analysis of CO2-water separation in a horizontal double T-junction
    • Milad Amiri
    • Paweł Ziółkowski
    • Kamil Stasiak
    • Dariusz Mikielewicz
    2022 Full text

    Carbon dioxide is considered one of the main factors leading to global warming. Considering the significant impacts of CO2 on climate change, various technologies have been developed in recent decades to control carbon emission, such as for example CO2 capture and storage. The developed cycle of a negative CO2 emission power plant includes some devices, out of which, separator plays an indispensable role. To this end, T-junction separator is widely used as a phase separation component to separate two-phase flow because of its simple structure and low cost. Previous studies suggest that an increase in the number of T-junction branches is conducive to raise phase separation efficiency. In this paper, the numerical simulation in a single T-junction separator is compared with the predicted values generated by experimental models based on air-water. Then, air has been replaced with CO2 and such separation process in a double T-junction separator has been scrutinized. In addition, the pressure distribution and phase separation performance of two-phase flow of CO2-water in a horizontal double T-junctions is studied.

  • Numerical analysis of high temperature minichannel heat exchanger for recuperative microturbine system
    • Jan Wajs
    • Tomasz Kura
    • Dariusz Mikielewicz
    • Elżbieta Fornalik-Wajs
    • Jarosław Mikielewicz
    2022 Full text ENERGY

    Considering the development of energy sector, distributed small-scale power generation, e.g., gas micro-CHP, is attracting considerable interest. In such installations, the heat exchanger is one of the key components possessing a significant influence on overall performance. Most studies concentrate on units operating below 900C, which do not fulfil the requirements of gas micro-CHP. Therefore, there remains a challenge to design a compact heat exchanger with passive technologies of heat transfer enhancement. This work describes the implementation of the own construction of a plate minichannel heat exchanger for high-efficiency gas microturbine engines with an external combustion chamber, supplied with air at a temperature of about 1000C. The results of this study will greatly contribute to the increase of system efficiency. To understand transport phenomena occurring inside it, a numerical model of the entire heat exchanger was developed in OpenFOAM. Defined boundary conditions were based on experimental data used also to validate the numerical model. The pressure drop experimental and numerical results agreed within the 2%-14% range, while the heat rate ones e within the 1%-8% of the range. In addition, numerical analysis exhibited the limits of thermal and exergetic efficiency values possible to be obtained, when the boundary conditions are strongly controlled.

  • Numerical analysis of lumbar spine injury during road safety barrier collision
    • Łukasz Pachocki
    2022

    Purpose: Enhancing road safety is a critical goal worldwide, necessitating the development of clear standards for road safety systems. This study focuses on lumbar spine (L-spine) compression injuries during collisions with concrete road safety barriers (RSBs). It aims to analyze internal forces during impact to understand L-spine injury biomechanics in such accidents. Methods: The research included a literature review, analyzing American guidelines and European standard EN1317. A normative TB41 crash test with a concrete RSB class H2/W5/B was conducted, followed by a finite element model creation and validation. Additionally, a TB32 test simulation with the same barrier and a 50th percentile female body model was performed to analyze L-spine displacements. These displacements were applied to a detailed L-spine model based on THUMS v.6.1, modified for validation test compliance. Results: Numerical models for the concrete RSB and L-spine were validated against experimental data. The TB41 crash test showed that connections between barrier segments experienced splitting failure, with a maximum dynamic compressive force of 350 kN and bending moments up to 130 kNm. The TB32 crash test indicated that vehicle collision energy dissipation caused the car to launch upwards and land along the barrier. This resulted in high internal forces in the L-spine, particularly in the L3 vertebra with a compressive force of about 2.7 kN and a bending moment of 39.5 Nm. Conclusions: The study observed splitting failure in the H2/W5/B concrete barrier during the TB41 test. Discrepancies were noted between the safety levels indicated by impact severity indices and those suggested by L-spine injury measures. These findings suggest a need to reevaluate the current standards for road safety systems, considering both barrier integrity and potential spinal injuries.

  • Numerical analysis of vacuum drying of a porous body in the integrated domain
    • Milad Amiri
    • Mohammad Bagher Ayani
    • Paweł Ziółkowski
    • Dariusz Mikielewicz
    2022 Full text JOURNAL OF FOOD PROCESS ENGINEERING

    n the present study, the vacuum drying process of an apple slice is numerically modeled based on a control volume method. Transient two-dimensional Navier– Stokes, energy, moisture, and Luikov equations are solved by numerical coding (Fortran) to simulate the simultaneous heat and mass transfer in the ambient and apple slice, respectively. The privilege of using Luikov's model is that the capillary forces are considered, and a differentiation between air, vapor, liquid, and solid is made. Luikov described the two phenomena associated with the transport of air, vapor, and liquids through the porous media as molecular transport and molar transport. The ambient pressure linearly reduced within a minute until it reached a constant value. One of the intellectually demanding preoccupations among researchers is how to simulate the sample and its surroundings with high accuracy of boundary conditions, which enables to avoid the use of empirical transfer coefficients. This study can be scrutinized from various dimensions, among which nonuse of boundary condition between a porous sample and its surroundings is the most conspicuous novelty. Results showed that although at 50 s, isothermal and iso-moisture lines inside the sample are symmetric, they are not symmetric at 100, 200, and 400 s. In addition, at first minute, pump operation leads to vary the density of the isothermal and isomoisture lines around the sample, but at 100, 200, and 400 s, higher temperature and moisture gradients have been achieved at the right and top of the sample surface

  • Numerical analysis on axial capacity of steel built-up battened columns
    • Paweł Pieczka
    • Piotr Iwicki
    2022 Full text Archives of Civil Engineering

    This paper deals with the numerical analysis aimed at study the bearing capacity of pinended steel built-up columns under axial compression. Finite element (FE) models were performed for the columns presented in the literature. The main problem discussed in the article is the shape and magnitude of geometric imperfections introduced into the numerical FE model, necessary to obtain the load capacity consistent with the experimental strength tests. Three types of numerical analysis that can be used in Abaqus program to calculate the load bearing capacity have been described. The imperfections possible to introduce for built-up columns were presented and an equivalent imperfection corresponding to both imperfections recommended by Eurocode 3 (global of the entire column and local of the chord) for built-up members was proposed. The results of the geometrically and materially nonlinear static analysis were compared with the calculations according to the code procedures (Eurocode 3 and PN-B03200:1990) and the results of experimental tests.

  • Numerical investigations of discrete crack propagation in Montevideo splitting test using cohesive elements and real concrete micro-structure
    • Beniamin Kondys
    • Jerzy Bobiński
    • Ireneusz Marzec
    2022

    The paper is aimed at accurately predicting the discrete fracture process in concrete specimens under complex stress states in two dimensional (2D) simulations. Plain concrete specimens subjected to Montevideo splitting test (MVD) were used for consideration due to non-negligible shear stresses impact in this type of test. In order to reflect the heterogeneous nature of the concrete, the meso-structure of the samples was included in the numerical models. The concrete was modelled as a four-phase material consisting of a cement matrix with air voids, aggregates and Interfacial Transitions Zones (ITZ) between aggregates and cement matrix. The meso-structure was created on the basis of X-ray μCT image of real specimens. The analysis was performed using the finite element method (FEM) with cohesive interface elements in a quasi-static approach carried out by Abaqus. The results of the numerical simulations were compared with the values obtained experimentally in terms of crack patterns and force versus crack mouth opening displacement (CMOD) diagrams.

  • Numerical methodology for evaluation the combustion and emissions characteristics on WLTP in the light duty dual-fuel diesel vehicle
    • Denys Stepanenko
    • Zbigniew Kneba
    • Jacek Rudnicki
    2022 Full text Combustion Engines

    The worldwide aim of reducing environmental impact from internal combustion engines bring more and more stringent emission regulations. In 2017 by EU has been adopted new harmonized test procedure called WLTP. In general terms this test was designed for determining the levels of harmful emissions and fuel consumption of traditional and hybrid cars. This procedure contains specific driving scenarios which representing reallife driving patterns. Test cycles contain vehicle velocity versus time profiles and directly in powertrain analysis on the test benches cannot be used. In order to back calculate drive cycles to engine rpm versus torque profiles a simple longitudinal vehicle dynamics method was used in this paper. Moreover, in order to determine most representative engine operation points duing WLTP a density based grid clustering method was implemented. The experimental part of the study focuses on the comparative evaluation of the effect of various diesel to LPG substitution ratios (0% LPG, 10% LPG, 20% LPG and 30% LPG) on combustion and emission characteristics of dual-fuel diesel engine

  • Numerical modelling and analysis of steel specimens subjected to marine immersed corrosion and tensile load
    • Krzysztof Wołoszyk
    • Yordan Garbatov
    2022 Full text

    The present study develops numerical models to analyse the behaviour of steel specimens subjected to marine immersed corrosion degradation and tensile load. The finite element method with the use of the explicit dynamic solver LS-DYNA, satisfying the quasi-static conditions, is employed. Two numerical models are developed, where in the first one, the scans of surfaces gathered from corroded plate specimens are implemented directly to the finite element model. In the second one, the corroded surfaces are generated using random fields. Three different plate thicknesses are investigated. The mechanical properties, i.e., yield stress, Young’s modulus, ultimate tensile stress, and total elongation, of specimens subjected to tensile loading for each numerical model are analysed. The results are validated against the experimental test, and failure modes are compared. It was found that both numerical models can estimate the mechanical properties of the corroded plate specimens and are very close to those of the experiment test. Thus, the random field modelling was very efficient in generating the real corroded plate surfaces of analysed specimens.

  • Numerical Modelling for Prediction of Compression Index from Soil Index Properties in Jimma town, Ethiopia
    • Worku Firomsa Kabeta
    • Feyessa Fufa Fekadu
    • Keneni Feyissa Yerosan
    2022 Full text U.Porto Journal of Engineering

    In this study, correlations are developed to predict compression index (Cc) from index parameters so that one can be able to model Jimma soils with compression index using simple laboratory tests. Undisturbed and disturbed soil samples from twelve different locations in Jimma town were collected. Laboratory tests like specific gravity, grain size analysis, Atterberg limit, and one-dimensional consolidation test for a total of twenty-four test samples were conducted. From one-dimensional consolidation tests, compressibility soil parameters (Cc and Cs) are determined. From the results of limited tests, an indicative good correlation is observed between Cc and LL, PL, and PI. However, a Poor correlation is developed between Cc and PL when related to the other parameters. The developed correlations will be important inputs in modeling Jimma clay soils with regression model and artificial neural networks (ANN) analysis using simple index tests. In addition, the results of this study can serve as a basis for further study of such correlations on different clay soils in the country. In this study, regression analysis was used to explore the significance of individual independent (index) soil properties. Regression model and correlation of compression index for liquid limit, plastic limit, and plasticity index were obtained from the linear regression analysis and ANN. This correlation will be helpful for geotechnical engineers in developing the coefficient of compression (Cc) value of expansive/clay soil from index properties. Finally, based on the general findings of the study, suitable recommendations have been forwarded.

  • Numerical Modelling of Forced Convection of Nanofluids in Smooth, Round Tubes: A Review
    • Janusz Cieśliński
    2022 Full text ENERGIES

    A comprehensive review of published works dealing with numerical modelling of forced convection heat transfer and hydrodynamics of nanofluids is presented. Due to the extensive literature, the review is limited to straight, smooth, circular tubes, as this is the basic geometry in shell-and-tube exchangers. Works on numerical modelling of forced convection in tubes are presented chronologically in the first part of the article. Particular attention was paid to the method of the solution of governing equations, geometry of the heating section, and boundary conditions assumed. Influence of nanoparticles on heat transfer and flow resistance are discussed. Basic information is summarized in tabular form, separately for single-phase approach and two-phase models. The second part of the article contains the correlation equations proposed in the presented papers for the calculation of the Nusselt (Nu) number or heat transfer coefficient, separately for laminar and turbulent flow. Details of the type of nanofluids, the concentration of nanoparticles, and the Reynolds (Re) number range are also presented. Finally, advantages and disadvantages of individual numerical approaches are discussed.

  • Numerically Efficient Miniaturization-Oriented Optimization of an Ultra-Wideband Spline-Parameterized Antenna
    • Adrian Bekasiewicz
    • Piotr Kurgan
    • Sławomir Kozieł
    2022 Full text IEEE Access

    Design of ultra-wideband radiators for modern handheld applications is a challenging task that involves not only selection of an appropriate topology, but also its tuning oriented towards balancing the electrical performance and size. In this work, a low-cost design of a compact, broadband, spline-parameterized monopole antenna has been considered. The framework used for the structure design implements trust-region-based methods, space mapping correction mechanisms, and a meta-optimization loop that permits a gradual increase of the problem dimensionality. The optimized structure is characterized by small dimensions of 11.4 mm × 17.2 mm and an overall footprint of only 195 mm2. The radiator operates within 3.1 GHz to 12 GHz bandwidth with the reflection coefficient amplitude level of around –10 dB. The computational cost of the structure design amounts to just 163 simulations of the high-fidelity EM model, which is low having in mind that the antenna is represented by a total of 38 adjustable parameters. The optimized radiator has been compared against state-of-the-art structures from the literature. Benchmarking of the presented optimization algorithm has also been performed. Numerical results have been confirmed by measurements of the fabricated antenna prototype.

  • Nutrients and Bioactive Components of Human Milk After one Year of Lactation. Implication for Human Milk Banks
    • Elena Sinkiewicz-Darol
    • Dorota Martysiak-Żurowska
    • Małgorzata Puta
    • Iwona Adamczyk
    • Olga Barbarska
    • Aleksandra Wesołowska
    • Urszula Bernatowicz-Łojko
    2022 JOURNAL OF PEDIATRIC GASTROENTEROLOGY AND NUTRITION

    Objective: Specifying the nutrient content and bioactive compounds in milk from long-term lactation for the purpose of finding additional sources of donors’ milk for HMBs. Method: Human milk samples were collected from 43 mothers of term infants (term infant human milk, TIHM) (3–6 weeks of lactation) and 50 mothers who have breastfed for over a year (long-nursing human milk, LNHM). The milk collection time was 24 hours. The analyses of fat, protein, carbohydrate and energy content were performed with human milk analyser MIRIS; lactoferrin and vitamin C content using RP-HPLC; total antioxidant activity (TAC) and lysozyme by ELISA; and the activity of glutathione peroxidase (GPx) and catalase (CAT) via spectrophotometric methods. Sociodemographic characteristics of both groups of mothers have been compiled. Results: Higher fat content and energy value was found in LNHM than in TIHM. Protein content in LNHM and TIHM did not differ. Carbohydrate content was lower in LNHM than in TIHM. TAC, CAT and GPx activity were higher in LNHM compared to TIHM. No significant differences in the content of lysozyme, lactoferrin and vitamin C between the studied groups were found. Conclusions: The findings suggest that after 12 months of lactation, human milk still has significant nutritional value, does not lose bioactive components and can be considered for use in human milk banks

  • O nieposzanowaniu języka w chromatografii
    • Zygfryd Witkiewicz
    • Waldemar Wardencki
    2022 Analityka: Nauka i Praktyka

    W pracy przedstawiono najczęstsze błęy popełniane w języku polskim w mowie i piśmie dotyczące chromatografii.

  • O symbolicznej pregnancji
    • Przemysław Parszutowicz
    2022 Full text Archiwum Historii Filozofii i Myśli Społecznej

    The aim of the article is to introduce and demonstrate the specificity of Cassirer ̓s concept of symbolic pregnancy. This concept is considered by many scholars to be the most important, root concept of his entire philosophy of symbolic forms. It constitutes the originality of his phenomenology in comparison with that of Husserl, Brentano, Scheler or Heidegger.

  • O związku pomiędzy obserwacją przyrody i projektowaniem. W kierunku struktur bionicznych i zrównoważonych
    • Anna Górka
    • Agnieszka Kurkowska
    2022

    Przyroda dostarcza wielu inspiracji dla projektowania architektonicznego. Doznania i refleksje dotyczące ukształtowania i struktury form bionicznych wynikających z wnikliwych obserwacji w terenie wykorzystać można w twórczym procesie projektowania bezpiecznych schronień, posługując się szkicem, modelem i jego umiejscowieniem w konkretnym miejscu. Przedstawiony proces twórczy stał się doświadczeniem uczestników Szkoły Letniej, poprzez „zanurzenie w Kaszubach”, stworzenie modeli schronień opartych na lokalnych elementach przyrodniczych .

  • Ocena nośności konstrukcji pylonu Mostu Rędzińskiego po 10 latach eksploatacji. Propozycje działań utrzymaniowych
    • Krzysztof Żółtowski
    • Mikołaj Binczyk
    • Przemysław Kalitowski
    2022 Przegląd Budowlany

    Pylon mostu podwieszonego jest głównym elementem konstrukcyjnym przenoszącym niemal całe obciążenie z przęseł na fundamenty. W Moście Rędzińskim bardzo ważną rolę w pracy pylonu odgrywa rygiel dolny. Jest to żelbetowy element obciążony rozporem wynikającym z pochylenia nóg pylonu oraz reakcjami z przęseł. Jest zatem silnie rozciąganą i zginaną belką, ekscentrycznie sprężoną. Po ujawnieniu zarysowań w ryglu przystąpiono do kompleksowej oceny problemu. W artykule opisano budowę modelu numerycznego oraz wykonane obliczenia. Rezultaty obliczeń wskazały na silną zależność pomiędzy rozkładem poprzecznym reakcji z przęseł, a wytężeniem rygla. Wynika to z zastosowania sprężenia ekscentrycznego oraz trudności w precyzyjnym określeniu rozkładu sił przekazywanych przez przęsło bezpośrednio na rygiel. Podsumowaniem przeprowadzonych analiz jest propozycja wykonania dodatkowego sprężenia zewnętrznego rygla dolnego pylonu w celu podniesienia nośności oraz wydłużenia trwałości.

  • Ocena własności dynamicznych silnika z zapłonem samoczynnym na podstawie zmian wartości wskaźnika działania.
    • Jacek Rudnicki
    2022 Full text Journal of Polish CIMEEAC

    W artykule przedstawiono koncepcję metody pozwalającej na ocenę działania silnika pracującego na charakterystyce regulatorowej w nagłej zmiany obciążenia i związanej z tym akceleracji/deceleracji. Do analizy przebiegu zmian podstawowych własności użytkowych silnika w tym czasie wykorzystane zostało wartościujące (ilościowe) ujęcie działania interpretowanego jako pewna wielkość fizyczna. Podejście takie umożliwia jednoczesne uwzględnienie wykonywania określonej pracy (podejście energetyczne) oraz czasu, w którym ta praca jest wykonana.

  • Ocena wpływu wymiarów wypełnienia kontrolowanego i rezystywności cieplnej ziemi rodzimej na obciążalność długotrwałą kabli elektroenergetycznych
    • Stanisław Czapp
    • Marian Czapp
    • Seweryn Szultka
    • Adam Tomaszewski
    2022

    Rezystywność cieplna ziemi ma istotny wpływ na obciążalność prądową długotrwałą elektroenergetycznych linii kablowych. W przypadku niekorzystnej rezystywności cieplnej można zastosować wypełnienie kontrolowane, czyli wymianę ziemi wokół kabli na substancję o znanych parametrach cieplnych. Wyznaczenie obciążalności długotrwałej z wypełnieniem kontrolowanym jest kłopotliwe, ponieważ na jej wartość wpływ ma zarówno rezystywność cieplna, jak i geometria tego wypełnienia. W rozdziale przeanalizowano wpływ rezystywności cieplnej ziemi rodzimej oraz wymiarów wypełnienia kontrolowanego na obciążalność prądową długotrwałą przykładowej linii kablowej. Analizy wykonano z wykorzystaniem programu ANSYS Fluent. Zaproponowano współczynniki poprawkowe obciążalności linii w zależności od wymiarów omawianego wypełnienia.

  • Ochrona i konserwacja architektury modernistycznej Gdyni - niektóre kierunki obecnych działań
    • Robert Hirsch
    2022

    Tekst przedstawia bieżące działania konserwatorskie i restauratorskie dotyczące architektury modernistycznej Gdyni

  • Ochrona mat wibroizolacyjnych przed uszkodzeniami na skutek obciążeń od nawierzchni kolejowych
    • Remigiusz Duszyński
    2022 Full text Przegląd Komunikacyjny

    Wykorzystanie mat wibroizolacyjnych staje się coraz powszechniejsze. Na rynku dostępne są maty wykonane z poliuretanu, wełny mineralnej oraz granulatu gumowego łączonego spoiwem poliuretanowym. Producenci deklarują dla swoich wyrobów skuteczne tłumienie drgań, niski współczynnik przesztywnienia dynamicznego, a także zwiększenie trwałości nawierzchni. Deklarowane zalety są jednak ściśle związane z rodzajem konstrukcji dróg szynowych. O ile w przypadku mat podpłytowych nie występują krytyczne czynniki mogące w krótkim czasie prowadzić do uszkodzenia mat o tyle maty podtłuczniowe, stosowane w nawierzchniach podsypkowych, poddane są destrukcyjnemu oddziaływaniu ułożonego na ich powierzchni tłucznia.

  • Ochrona przeciwporażeniowa w sieciach elektroenergetycznych o napięciu wyższym niż 1 kV
    • Stanisław Czapp
    2022 Full text Inżynier Budownictwa

    W artykule przedstawiono wymagania norm odnoszące się do ochrony przeciwporażeniowej w stacjach elektroenergetycznych wysokiego napięcia oraz w elektroenergetycznych liniach napowietrznych wysokiego napięcia. Omówiono również wpływ doziemienia po stronie wyższego napięcia w stacjach transformatorowych SN/nn na zagrożenie porażeniowe w sieciach rozdzielczych niskiego napięcia.

  • Od demiurga do twórczego koordynatora. Ewolucja warsztatu architekta po 1995 r.
    • Michał Leszczyński
    2022 Full text

    Rozprawa zajmuje się rozważaniem na temat charakteru twórczego profesji. Postrzeganie społeczne i funkcja, jaka przepisywana była architektom i urbanistom, rola twórcy – demiurga, ustępuje dziś miejsca roli architekta – koordynatora. Praca podejmuje próbę deskrypcji zmian zachodzących w warsztacie pracy architekta, poprzez badanie dorobku twórczego pracowni Grupa 5 Architekci, której działalność przypada na okres transformacji ustrojowej w Polsce przełomu XX i XXI w. Analiza kolejnych projektów, realizowanych w cyklu projektowo - nadzorczo – inwestycyjnym przez zespół architektów rozszerzających zakres swojej działalności z biegiem lat i pozyskiwanych doświadczeń, pozwala na zdefiniowanie modeli badawczych. Modele poddane zostają weryfikacji w oparciu o przeprowadzenie wywiadów pogłębionych z innymi architektami rozwijającymi działalność projektową równolegle z biurem Grupa 5 Architekci w badanym okresie. Sprzężenie modeli opisujących ewolucję warsztatu pracy z wynikami przeprowadzonych wywiadów pozwala na sformułowanie złożonych modeli łącznych. Autor pracy postuluje, aby stale odnajdywać się w dynamice zmian. Powinno to znaleźć przełożenie na edukację oraz praktykę zawodową, które będą zorientowane na innowację, szeroko rozumiany zrównoważony rozwój oraz zwiększanie efektywności procesu projektowo – realizacyjnego. Zaangażowanie w badania i rozwój oraz odpowiednie przygotowanie i właściwa postawa warunkują zarazem przetrwanie i dalszy rozwój zawodu architekta.

  • Od zrównoważonego rozwoju do dewzrostu - paradygmaty krytyczne wobec wzrostu i ich implikacje dla planowania przestrzennego
    • Izabela Mironowicz
    • Robert Skrzypczyński
    2022 Full text SAMORZĄD TERYTORIALNY

    Pomimo ponad trzech dekad wdrażania koncepcji zrównoważonego rozwoju środowisko Ziemi ulega dalszej degradacji i destabilizacji. Sytuacja ta przekłada się na ożywienie antycypowanej już w latach 70. XX w. krytyki założeń leżących u podstaw koncepcji zrównoważonego rozwoju – spośród których kluczowe wydaje się założenie możliwości rozłączenia (decoupling) wzrostu gospodarczego i negatywnego oddziaływania na środowisko. W niniejszym artykule poddajemy pod krytyczną dyskusję wizję decouplingu, a następnie omawiamy trzy alternatywne wobec zrównoważonego rozwoju koncepcje „postwzrostowe” – dewzrost, ekonomię obwarzanka i gospodarkę stacjonarną – oraz wskazujemy na implikacje, jakie płyną z wdrażania postulatów dewzrostu dla teorii i praktyki planowania przestrzennego. Wydaje się, że planowanie przestrzenne powinno z jednej strony zaadaptować się do rysującej się na horyzoncie zmiany paradygmatów, a z drugiej wspierać transformację dewzrostową, co jest możliwe na różne sposoby także z wykorzystaniem już istniejących narzędzi planistycznych.

  • Odbiór zbiorczy z filtracją adaptacyjną RLS w transmisji danych w kanale hydroakustycznym
    • Agnieszka Czapiewska
    • Andrzej Łuksza
    • Ryszard Studański
    • Andrzej Żak
    2022 Full text Przegląd Elektrotechniczny

    Transmisja danych w kanale hydroakustycznych realizowana jest w trudnych warunkach propagacyjnych. Jednym z problemów podczas takiej transmisji są zakłócenia międzysymbolowe (ISI – intersymbol interference) spowodowane głównie przez efekt wielodrogowości. To zjawisko utrudnia, bądź uniemożliwia transmisję danych w takim kanale. Stąd podjęto analizę wpływu zastosowania odbioru zbiorczego oraz filtracji adaptacyjnej RLS (Recursive Least Squares) na poprawę jakości odbioru transmisji danych w kanale hydroakustycznym.

  • Olfactory receptor-based biosensors as potential future tools in medical diagnosis
    • Tomasz Wasilewski
    • Nathália F. Brito
    • Bartosz Szulczyński
    • Marek Wojciechowski
    • Natalia Buda
    • Ana Claudia A. Melo
    • Wojciech Kamysz
    • Jacek Gębicki
    2022 TRAC-TRENDS IN ANALYTICAL CHEMISTRY

    The detection of biomarkers is the future of non-invasive medical diagnosis and screening. Discovery and identification of reliable disease specific volatile organic compounds is dependent on repeatable, accurate analysis of trace level gaseous analytes mainly in breath samples. Natural variety of the olfactory systems and the compounds capable of gas molecules binding creates wide possibilities of acquisition and implementation of the biological elements for construction of the biosensors for different applications, with special emphasis on healthcare and medical areas. Early and fast diagnosis of patient's condition, including respiratory system diseases, as well as on-time launch of suitable treatment are the critical factors influencing on public health and efficiency of clinical trials. Conventional techniques of diagnosis of the respiratory system diseases are usually time-consuming, require centralized laboratories, experienced personnel and expensive equipment. Recently developed biosensors take advantage of micro- and nanotechnology achievements, which significantly improve their metrological parameters. A transfer of the biosensors from scientific laboratories to actual clinic diagnostics is limited and requires overcoming of critical obstacles. Potential use of olfactory receptors and elements mimicking their operation in artificial olfaction for their use in biosensors in disease diagnosis are presented. We review recent progress in olfactory-based biosensors employing different biological units in light of future developments in medical diagnosis with emphasis on examples where biological components have been employed to detect biomarkers. Also, significant advances over the last years were discussed and features of fabrication in the perspective of odorant sensing applications. Pioneering studies that greatly impacted the field of biosensing are critically reviewed along with future challenges to overcome.

  • On a comparison principle and the uniqueness of spectral flow
    • Maciej Starostka
    • Nils Waterstraat
    2022 Full text MATHEMATISCHE NACHRICHTEN

    The spectral flow is a well-known quantity in spectral theory that measures the variation of spectra about 0 along paths of selfadjoint Fredholm operators. The aim of this work is twofold. Firstly, we consider homotopy invariance properties of the spectral flow and establish a simple formula which comprises its classical homotopy invariance and yields a comparison theorem for the spectral flow under compact perturbations. We apply our result to the existence of non-trivial solutions of boundary value problems of Hamiltonian systems. Secondly, the spectral ow was axiomatically characterised by Lesch, and by Ciriza, Fitzpatrick and Pejsachowicz under the assumption that the endpoints of the paths of selfadjoint Fredholm operators are invertible. We propose a different approach to the uniqueness of spectral flow which lifts this additional assumption. As application of the latter result, we discuss the relation between the spectral flow and the Maslov index in symplectic Hilbert spaces.

  • On a flexomagnetic behavior of composite structures
    • Mohammad Malikan
    • Victor Eremeev
    2022 Full text INTERNATIONAL JOURNAL OF ENGINEERING SCIENCE

    The popularity of the studies is getting further on the flexomagnetic (FM) response of nano-electro-magneto machines. In spite of this, there are a few incompatibilities with the available FM model. This study indicates that the accessible FM model is inappropriate when considering the converse magnetization effect that demonstrates the necessity and importance of deriving a new FM relation. Additionally, the literature has neglected the converse FM coefficient in the Lifshitz invariant inside the free energy constitutive relation. This fact inspires us to endeavor and conduct a new characteristic formulation for static analysis of axially compressed piezomagnetic nanobeams comprising the FM effect. This novel FM model is competent and suitable for various boundary conditions, encompassing analytical, semi-analytical, and numerical solving strategies. However, based on the previous FM equation established with respect to Euler-Bernoulli and Timoshenko beams, the governing equations are ill-posed due to the corresponding energy density. Despite that, this error will not remain in the finalized equations in the present model by conjecturing a gradient of the magnetic field and a different formulation. Moreover, the inverse FM parameter will appear in the magnetic field relation. As the literature reported, non-uniform deformed piezomagnetic structures are capable of presenting more outstanding flexomagneticity. In actuality, a non-uniform elastic strain appears as a response to the magnetic field gradient (converse effect) that causes this study to deduce the nanobeam with higher-order shear deformations. Furthermore, the local governing equations will be transferred into the nonlocal phase according to the nonlocal differential, particularly nonlocal integral elasticity which itself is a strong nonlocality. Through this theory, and in regard to the converse FM impact, an analytical expression is applied for computing critical buckling loads within several ends conditions of the nanobeam. Our present results and achievements will hopefully be an effective contribution to theoretical studies on the mechanics of intelligent nanostructures.

  • On Computing Curlicues Generated by Circle Homeomorphisms
    • Justyna Signerska-Rynkowska
    2022 Full text

    The dataset entitled Computing dynamical curlicues contains values of consecutive points on a curlicue generated, respectively, by rotation on the circle by different angles, the Arnold circle map (with various parameter values) and an exemplary sequence as well as corresponding diameters and Birkhoff averages of these curves. We additionally provide source codes of the Matlab programs which can be used to generate and plot the first N points of curlicues of these types and calculating related quantities. Illustrative figures are included as well.

  • On Decision-Making Strategies for Improved-Reliability Size Reduction of Microwave Passives: Intermittent Correction of Equality Constraints and Adaptive Handling of Inequality Constraints
    • Sławomir Kozieł
    • Anna Pietrenko-Dąbrowska
    • Marzieh Mahrokh
    2022 KNOWLEDGE-BASED SYSTEMS

    Design optimization of passive microwave components is an intricate process, especially if the primary objective is a reduction of the physical size of the structure. The latter has become an important design consideration for a growing number of modern applications (mobile communications, wearable/implantable devices, internet of things), where miniaturization is imperative due to a limited space allocated for the electronic circuitry. Optimization-based size reduction is a heavily constrained task, with several acceptance thresholds imposed on electrical characteristics of the system. The challenges are pronounced whenever equality constraints are involved (e.g., related to power split ratio requirements), in which case the feasible space is a thin set, thereby difficult to be explored throughout the optimization process. This feature makes conventional methods, such as penalty function approaches or algorithms with explicit constraint handling, of limited reliability. In this paper, we introduce a novel technique for reliable control of equality constraints in simulation-driven size reduction of microwave components. Our methodology involves an intermittent optimization-based correction of equality constraints. This is essentially a knowledge-based decision-making strategy implemented as a supplementary optimization stage, and launched before each iteration of the core algorithm. Constraint violation is reduced without being detrimental to the remaining figures of merit, in particular, the circuit size and inequality constraints. Meanwhile, inequality constraints are handled using a penalty function approach with adaptive adjustment of penalty coefficients. The proposed technique facilitates exploration of the feasible space, and allows for achieving reduced miniaturization rates in comparison to the benchmark methods, while ensuring a reliable control of the design constraints. These advantages have been demonstrated using four microstrip couplers, with consistent results obtained for all considered circuits.

  • ON DYNAMICS OF ELASTIC NETWORKS WITH RIGID JUNCTIONS WITHIN NONLINEAR MICRO-POLAR ELASTICITY
    • Victor Eremeev
    • Emanuele Reccia
    2022 Full text International Journal for Multiscale Computational Engineering

    Within the nonlinear micropolar elasticity we discuss effective dynamic (kinetic) properties of elastic networks with rigid joints. The model of a hyperelastic micropolar continuum is based on two constitutive relations, i.e., static and kinetic ones. They introduce a strain energy density and a kinetic energy density, respectively. Here we consider a three-dimensional elastic network made of three families of elastic fibers connected through massive rigid joints. Effective elastic properties are inherited from the geometry and material properties of the fibers, whereas the kinetic (inertia) properties are determined by the both fibers and joints. Formulae for microinertia tensors are given.

  • On Earth as in Universe
    • Krzysztof Wróblewski
    2022

    On Earth as in Universe Ślady zostawione na podobraziu przygotowanym własnoręcznie przez Kazimierza Ostrowskiego. Kilka pociągnięć pędzlem ciemną farbą na odwrocie płótna, tu i ówdzie przyklejone włosy do powierzchni gruntu, kurz nagromadzony przez lata - słowem każdy element artefaktu, który trafił do mnie, był kapsułą czasu sprzed około pięćdziesięciu lat. Jedyne co mogłem zrobić, to wpisać drobiny obecności Kazimierza Ostrowskiego w strukturę malowanego obrazu. Odnosząc się luźno do twórczości Kacha użyłem dwóch przetworzonych wzorów opracowanych przez Rogera Penrose'a. Ich bazą są symetrie pięcioosiowe wynikające ze złotego podziału. Zarówno na Ziemi jak i w Kosmosie panuje matematyczny porządek, choć na co dzień tego nie dostrzegamy. Na początku XVII wieku mówił o tym Johanes Kepler w Harmonices Mundi twierdząc, że geometryczne obiekty są modelami całego świata. Ówczesne obserwacje i wnioski Keplera potwierdzają współczesne badania, według których gdy weźmiemy dwie planety z Układu Słonecznego, połączymy ich pozycje linią i będziemy na bieżąco monitorować ich wzajemne położenie, to naszym oczom ukażą się wzory o określonych regularnych kształtach. Na lewym marginesie obrazu umieściłem nawiązanie do symetrii występujących w różnych liściach. W górnym lewym rogu kompozycji znajduje się ponadto detal zaprzeczony z jednego obrazów Hilmy af Klint z cyklu zatytułowanego Ewolucja. Artystka była przekonana, że przemianę napędza zasada polaryzacji występująca w różnych formach, takich jak światło i ciemność, dobro i zło, mężczyzna i kobieta. Jej symboliczne, czy wręcz mistyczne malarstwo jest mi szczególnie bliskie. Znajduję też pewne konotacje pomiędzy dokonaniami Hilmy af Klint i Kazimierza Ostrowskiego - choć jego twórczość miała bardziej charakter alegoryczny. Malarstwo Kazimierza Ostrowskiego w moim przekonaniu spajało i monumentalizowało to, czego doświadczamy na Ziemi z tym co dzieje się we Wszechświecie. Nie opierało się ono wprawdzie na rygorystycznej geometrii, ale rządził nim intuicyjny zmysł porządku, wyczucie równowagi i harmonii. Kachu podobnie jak Lèger „dbał o płaszczyznę” a „kompozycja musiała mieć równowagę od brzegu do brzegu” . Krzysztof Wróblewski Gdańsk, 2022

  • On Improved-Reliability Design Optimization of High-Frequency Structures Using Local Search Algorithms
    • Sławomir Kozieł
    • Anna Pietrenko-Dąbrowska
    • Piotr Płotka
    2022 Full text IEEE Access

    The role of numerical optimization has been continuously growing in the design of high-frequency structures, including microwave and antenna components. At the same time, accurate evaluation of electrical characteristics necessitates full-wave electromagnetic (EM) analysis, which is CPU intensive, especially for complex systems. As rigorous optimization routines involve repetitive EM simulations, the associated cost may be significant. In the design practice, the most widely used EM-driven procedures are by far local (e.g., gradient-based) ones. While typically incurring acceptable expenses that range from dozens to a few hundreds of objective function evaluations, they are prone to failure whenever a decent initial design is not available. Representative scenarios include simulation-based size reduction of compact devices or re-design of structures for operating/material parameters being distant from those at the available design. A standard mitigation approach is the involvement of global search methods, which entails significantly higher computational costs. This paper reviews the recent methodologies introduced to improve the reliability of local parameter tuning algorithms without degrading their computational efficiency. We discuss frequency-based regularization, adaptively adjusted design specification approach, as well as accelerated feature-based optimization. All of these techniques incorporate mechanisms that improve the performance of the search process under challenging scenarios, primarily poor initial conditions. The outline of the mentioned methods is accompanied by illustrative examples including passive microwave circuits and microstrip antennas. Benchmarking against conventional local search is provided as well. Furthermore, the paper discusses the advantages and disadvantages of the reviewed frameworks as well as speculates about future research directions.

  • On proper (1,2)‐dominating sets in graphs
    • Adrian Michalski
    • Iwona Włoch
    • Magda Dettlaff
    • Magdalena Lemańska
    2022 MATHEMATICAL METHODS IN THE APPLIED SCIENCES

    In 2008, Hedetniemi et al. introduced the concept of (1,)-domination and obtained some interesting results for (1,2) -domination. Obviously every (1,1) -dominating set of a graph (known as 2-dominating set) is (1,2) -dominating; to distinguish these concepts, we define a proper (1,2) -dominating set of a graph as follows: a subset is a proper (1,2) -dominating set of a graph if is (1,2) -dominating and it is not a (1,1) -dominating set of a graph. In particular, we introduce proper (1,2) -domination parameters and study their relations with (1,2) -domination parameters and the classical domination numbers.

  • On reliability assessment of ship machinery system in different autonomy degree; A Bayesian-based approach
    • Ahmad BahooToroody
    • Mohammad Mahdi Abaei
    • Osiris Valdez Banda
    • Jakub Montewka
    • Pentti Kujala
    2022 Full text OCEAN ENGINEERING

    Analyzing the reliability of autonomous ships has recently attracted attention mainly due to epistemic uncertainty (lack of knowledge) integrated with automatic operations in the maritime sector. The advent of new random failures with unrecognized failure patterns in autonomous ship operations requires a comprehensive reliability assessment specifically aiming at estimating the time in which the ship can be trusted to be left unattended. While the reliability concept is touched upon well through the literature, the operational trustworthiness needs more elaboration to be established for system safety, especially within the maritime sector. Accordingly, in this paper, a probabilistic approach has been established to estimate the trusted operational time of the ship machinery system through different autonomy degrees. The uncertainty associated with ship operation has been quantified using Markov Chain Monte-Carlo simulation from likelihood function in Bayesian inference. To verify the developed framework, a practical example of a machinery plant used in typical short sea merchant ships is taken into account. This study can be exploited by asset managers to estimate the time in which the ship can be left unattended.

  • On solvability of initial boundary-value problems of micropolar elastic shells with rigid inclusions
    • Victor Eremeev
    • Leonid Lebedev
    • Violetta Konopińska-Zmysłowska
    2022 Full text MATHEMATICS AND MECHANICS OF SOLIDS

    The problem of dynamics of a linear micropolar shell with a finite set of rigid inclusions is considered. The equations of motion consist of the system of partial differential equations (PDEs) describing small deformations of an elastic shell and ordinary differential equations (ODEs) describing the motions of inclusions. Few types of the contact of the shell with inclusions are considered. The weak setup of the problem is formulated and studied. It is proved a theorem of existence and uniqueness of a weak solution for the problem under consideration.

  • On the Bending of Multilayered Plates Considering Surface Viscoelasticity
    • Victor Eremeev
    • Violetta Konopińska-Zmysłowska
    2022

    We discuss the bending resistance of multilayered plates taking into account surface/interfacial viscoelasticity. Within the linear surface viscoelasticity we introduce the surface/interfacial stresses linearly dependent on the history of surface strains. In order to underline the surface viscoelasticity contribution to the bending response we restrict ourselves to the elastic behaviour in the bulk. Using the correspondence principle of the theory of viscoelasticity we present an effective bending relaxation function.

  • On the deformation and frequency analyses of SARS-CoV-2 at nanoscale
    • Shahriar Dastjerdi
    • Mohammad Malikan
    • Bekir Akgöz
    • Ömer Civalek
    • Tomasz Wiczenbach
    • Victor Eremeev
    2022 Full text INTERNATIONAL JOURNAL OF ENGINEERING SCIENCE

    The SARS-CoV-2 virus, which has emerged as a Covid-19 pandemic, has had the most significant impact on people's health, economy, and lifestyle around the world today. In the present study, the SARS-CoV-2 virus is mechanically simulated to obtain its deformation and natural frequencies. The virus under analysis is modeled on a viscoelastic spherical structure. The theory of shell structures in mechanics is used to derive the governing equations. Whereas the virus has nanometric size, using classical theories may give incorrect results. Consequently, the nonlocal elasticity theory is used to consider the effect of interatomic forces on the results. From the mechanical point of view, if a structure vibrates with a natural frequency specific to it, the resonance phenomenon will occur in that structure, leading to the destruction of the structure. Therefore, it is possible that the protein chains of SARS-CoV-2 would be destroyed by vibrating it at natural frequencies. Since the mechanical properties of SARS-CoV-2 are not clearly known due to the new emergence of this virus, deformation and natural frequencies are obtained in a specific interval. Researchers could also use this investigation as a pioneering study to find a non-vaccine treatment solution for the SARS-CoV-2 virus and various viruses, including HIV.

  • On the differential effect of temperature on the Nusselt-Rayleigh relationship in free convection
    • Michał Ryms
    • Grzegorz J. Kwiatkowski
    • Witold Lewandowski
    2022 INTERNATIONAL JOURNAL OF THERMAL SCIENCES

    The aim of and inspiration behind this paper was to explain the reasons, also observed by other researchers, of the discrepancy in the results of experimental free convection, which for small Rayleigh and Nusselt numbers in the initial phase of research can sometimes reach several hundred percent. These discrepancies decrease with increasing heating power and plate surface temperature, in proportion to the increase in Ra and Nu, reaching typical values for this type of research. To explain this phenomenon, a comprehensive theoretical and experimental analysis of the influence of the physical properties of a fluid (air and water) as well as primary (tw and t∞) and secondary (tav and Δt) temperatures on the Rayleigh number was carried out. The impact was found to be unequal. The plate temperature tw is of greater importance, which is much higher than the much lower and almost constant temperature t∞ of the undisturbed area, especially since it causes convective movement, generating differences in fluid density and thus driving the phenomenon. Similarly, the direct contribution of the temperature difference Δt to Ra suggests that it has a greater influence on convective heat transfer than the average temperature of the medium tav. By analysing the effect of each of these temperatures separately, it was possible to show that their mutual, compatible or opposite interaction (tw/t∞) causes a different scattering of results, or may even lead to unusual Rayleigh numbers (Ra temperature dualism). This study led not only to a better understanding of the phenomenon, but even to a prediction of its unusual behaviour, unheard of in typical experimental studies of free convection. For example, if we consider the theoretical convective heat transfer from a plate l = 0.15 m in air in the context of the interaction of tav and Δt, it turns out that for the same Δt = 40 K, the Rayleigh number may assume, depending on tav = (tw + t∞)/2, different values. So, for tw = 50 °C, t∞ = 10 °C and tav = 30 °C, Ra = 1.213.107, whereas for tw = 90 °C, t∞ = 50 °C and tav = 70 °C it is ≈ 1.7 times smaller (Ra = 0.687.107). This hypothetical phenomenon, unheard of in typical experimental studies, which could occur, and maybe even does occur in smelting, thermal energy, etc., forces us to think about the values of Nusselt numbers, heat transfer coefficients and heat fluxes for these two cases. This lies beyond the scope of the present paper, but it is a topic for possible future research.

  • On the Role of Polarimetric Decomposition and Speckle Filtering Methods for C-Band SAR Wetland Classification Purposes
    • Monika Gierszewska
    • Tomasz Berezowski
    2022 Full text IEEE Journal of Selected Topics in Applied Earth Observations and Remote Sensing

    Previous wetlands studies have thoroughly verified the usefulness of data from synthetic aperture radar (SAR) sensors in various acquisition modes. However, the effect of the processing parameters in wetland classification remains poorly explored. In this study, we investigated the influence of speckle filters and decomposition methods with different combinations of filter and decomposition windows sizes on classification accuracy. We used a C-band Radarsat 2 image acquired over a wetland located in northeast Poland. We processed the SAR data using various speckle filters: boxcar, intensity-driven adaptive-neighborhood (IDAN), improved Lee sigma, refined Lee (in 5×5 to 11×11 pixel window sizes), and a nonlocal NL-SAR. Next, we processed the nonfiltered and filtered data using nine polarimetric decompositions, also in 5×5 to 11×11 pixel window sizes. The extracted polarimetric features were applied as an input dataset in the random forest classification model in single- and multidecomposition scenarios. In the single-decomposition scenario, the Cloude–Pottier decomposition produced the highest (72%) and the Touzi decomposition achieved the lowest (38%) accuracy. The IDAN filter with an 11×11 filter window and a 9×9 decomposition window had the highest, and the nonfiltered data with a 5×5 decomposition window had the lowest accuracy in the multidecomposition scenario. The most important features were the alpha parameter from the Cloude–Pottier decomposition, the polarimetric contribution of the Shannon entropy, and the volume backscattering components. The results stress the importance of appropriate processing parameters in the SAR data classification workflow, and the study guides in selecting the most suitable combination of radar image processing parameters for wetland classification.

  • On the Use of Selected 4th Generation Nuclear Reactors in Marine Power Plants
    • Marta Drosińska-Komor
    • Jerzy Głuch
    • Łukasz Breńkacz
    • Paweł Ziółkowski
    2022 Full text Polish Maritime Research

    This article provides a review of the possibility of using different types of reactors to power ships. The analyses were carried out for three different large vessels: a container ship, a liquid gas carrier and a bulk carrier. A novelty of this work is the analysis of the proposal to adapt marine power plants to ecological requirements in shipping by replacing the conventional propulsion system based on internal combustion engines with nuclear propulsion. The subjects of comparison are primarily the dimensions of the most important devices of the nuclear power plant and the preliminary fitness analysis. It was assumed for this purpose that the nuclear power plant fits in the engine room compartment and uses the space left after the removal of the combustion engines. At the same time, this propulsion provides at all times sufficient energy for port, technological and shipping operations at an economically justifiable speed. For deep-sea vessels, which are supposed to reach null emissions of CO, CO2, NOx, SOx and H2O, this is one of the most reasonable solutions. Finally the paper proves that all the above-mentioned marine functions could be effectively applied in power plants equipped with 4th generation nuclear reactors.

  • On the use of the cumulative strain energy density for fatigue life assessment in advanced high-strength steels
    • Ricardo Branco
    • Rui F. Martins
    • José A.F.O. Correia
    • Zbigniew Marciniak
    • Wojciech Macek
    • J. Jesus
    2022 Full text INTERNATIONAL JOURNAL OF FATIGUE

    In this paper, the applicability of the cumulative strain energy density is explored as a fatigue indicator parameter for advanced high-strength steels subjected to strain-controlled conditions. Firstly, the cyclic stress-strain responses of nine steels, selected from three multiphase families, encompassing different elemental compositions and different heat treatment routes, were studied. Then, the predictive capabilities of the proposed model were compared to those of other strain-based and energy-based approaches. It was found that the cumulative strain energy density decreases as the strain amplitude rises and it can be correlated with the fatigue life via a power function. In addition, the dialectical relationship between the cumulative strain energy and the fatigue life was not significantly affected by the elemental composition or the heat treatment route. Furthermore, the fatigue lives computed through the cumulative strain energy density concept were close to those of the other models but were slightly more conservative.

  • On weak solutions of the boundary value problem within linear dilatational strain gradient elasticity for polyhedral Lipschitz domains
    • Victor Eremeev
    • Francesco dell'Isola
    2022 Full text MATHEMATICS AND MECHANICS OF SOLIDS

    We provide the proof of an existence and uniqueness theorem for weak solutions of the equilibrium problem in linear dilatational strain gradient elasticity for bodies occupying, in the reference configuration, Lipschitz domains with edges. The considered elastic model belongs to the class of so-called incomplete strain gradient continua whose potential energy density depends quadratically on linear strains and on the gradient of dilatation only. Such a model has many applications, e.g., to describe phenomena of interest in poroelasticity or in some situations where media with scalar microstructure are necessary. We present an extension of the previous results by Eremeyev et al. (2020 Z angew Math Phys 71(6): 1–16) to the case of domains with edges and when external line forces are applied. Let us note that the interest paid to Lipschitz polyhedra-type domains is at least twofold. First, it is known that geometrical singularity of the boundary may essentially influence singularity of solutions. On the other hand, the analysis of weak solutions in polyhedral domains is of great significance for design of optimal computations using a finite-element method and for the analysis of convergence of numerical solutions.

  • On zero-error codes produced by greedy algorithms
    • Marcin Jurkiewicz
    2022 Full text JOURNAL OF COMBINATORIAL OPTIMIZATION

    We present two greedy algorithms that determine zero-error codes and lower bounds on the zero-error capacity. These algorithms have many advantages, e.g., they do not store a whole product graph in a computer memory and they use the so-called distributions in all dimensions to get better approximations of the zero-error capacity. We also show an additional application of our algorithms.

  • Online Volatile Compound Emissions Analysis Using a Microchamber/Thermal Extractor Coupled to Proton Transfer Reaction-Mass Spectrometry
    • Y Lan Pham
    • Wojciech Wojnowski
    • Jonathan Beauchamp
    2022 Full text ANALYTICAL CHEMISTRY

    Indoor air is a complex and dynamic mixture comprising manifold volatile organic compounds (VOCs) that may cause physiological and/or psychological discomfort, depending on the nature of exposure. This technical note presents a novel approach to analyze VOC emissions by coupling a microchamber/thermal extractor (μ-CTE) system to a proton transfer reaction-mass spectrometer (PTR-MS). This configuration provides an alternative to conventional emissions testing of small objects. The dynamic emission profiles of VOCs from a representative 3D-printed model are presented as a proof-of-concept analysis. Emission profiles are related to the target compound volatility, whereby 2-propanol and acetaldehyde exhibited the highest emissions and most rapid changes compared to the less volatile vinyl crotonate, 2-hydroxymethyl methacrylate, and mesitaldehyde, which were present at lower concentrations and showed different dynamics. Comparative measurements of the emission profiles of these compounds either with or without prior static equilibration yielded stark differences in their dynamics, albeit converging to similar values after 15 min of sampling time. Further, the utility of this system to determine the time required to capture a specific proportion of volatile emissions over the sampling period was demonstrated, with a mean duration of 8.4 ± 0.3 min to sample 50% of emissions across all compounds. This novel configuration provides a means to characterize the dynamic nature of VOC emissions from small objects and is especially suited to measuring highly volatile compounds, which can present a challenge for conventional sampling and analysis approaches. Further, it represents an opportunity for rapid, targeted emissions analyses of products to screen for potentially harmful volatiles.