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Gdańsk University of Technology

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Publications from the year 2020

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  • Ocena stopnia denaturacji oraz zawartości hydroksyproliny w kosmetycznej bazie kolagenowej.
    • Szymon Mania
    2020

    W ramach zadania wykonano pomiary oraz opracowano wyniki dotyczące określenia temperatury denaturacji oraz zawartości hydroksyproliny w bazie kolagenowej.

  • Ocena zagrożenia korozyjnego zbiorników na terenie modernizowanego Terminala Paliw LOTOS w Piotrkowie Trybunalskim.
    • Krzysztof Żakowski
    • Kazimierz Darowicki
    • Łukasz Gaweł
    • Tadeusz Sonneck
    2020

    Zbadano zagrożenie korozyjne nowo budowanych zbiorników na terenie modernizowanego terminala paliw. Oceny dokonano na podstawie badań agresywności korozyjnej pobranych próbek gruntu oraz wykonanych pomiarów terenowych. Uzyskane wyniki będą wykorzystane przy projektowaniu systemu ochrony katodowej nowych zbiorników podziemnych.

  • Od postawy prozdrowotnej w stoczni jachtowej do ograniczania zagrożeń na stanowisku pracy formierza-laminiarza
    • Anna Dembicka
    • Katarzyna Mołas
    2020 Full text Problemy Jakości

    Tematyka zdrowia i bezpieczeństwa pracowników, coraz częściej popularyzowana w świecie biznesu, nadal stanowi dość mało rozpoznany obszar działalności polskich przedsiębiorstw. Niniejszy artykuł porusza ważką kwestię promocji zdrowia w miejscu pracy jako czynnika zwiększającego efektywność pracy oraz jego wpływ na osiąganie wysokiej jakości produktu. Publikacja omawia znaczenie postawy prozdrowotnej i sposobów jej kształtowania w przemyśle jachtowym na przykładzie pracy formierza-laminiarza. Uszczegółowionej analizie poddana zostaje kwestia zmniejszania uciążliwości i szkodliwości czynników występujących podczas naprawy błędów powstających w procesie laminowania jachtu. Artykuł wieńczą propozycje możliwych do wdrożenia aktywności prozdrowotnych zarówno w pracy, jak i poza miejscem pracy. Publikacja wchodzi w skład cyklu prezentującego różne aspekty zarządzania procesowego w przemyśle stoczni jachtowych. Artykuł koncentruje się na procesie zarządzania kapitałem ludzkim w świetle orientacji prozdrowotnej.

  • Oddziaływanie elektronów z wybranymi prekursorami metalicznych i półprzewodnikowych nanostruktur wytwarzanych za pomocą skupionych wiązek elektronowych
    • Sylwia Stefanowska-Tur
    2020 Full text

    Praca poświęcona jest oddziaływaniom elektronów z prostymi prekursorami metody FEBID. W szczególności wyznaczono oraz przeanalizowano całkowite przekroje czynne na rozpraszanie elektronów funkcji energii dla wybranych cząsteczek: SnCl4, TiCl4, C(CH3)4, Si(CH3)4 oraz Ge(CH3)4, C5H6. W ramach pracy badano korelacje pomiędzy wartościami całkowitych przekrojów czynnych, a wybranymi fizykochemicznymi wielkościami charakteryzującymi badane związki, takimi jak statyczna dipolowa polaryzowalność elektryczna oraz elektryczny moment dipolowy. Szczególną uwagę zwrócono na wpływ metylacji, w tetraedrycznych związkach węgla, krzemu i germanu, na efektywność procesu rozpraszania elektronów. Zbadano wpływ zmiany zarówno atomu centralnego, jak i zamiany atomów zewnętrznych w cząsteczce tetraedrycznej, na zależność energetyczną całkowitego przekroju czynnego. Przeprowadzone badania przyczyniają się do lepszego zrozumienia oddziaływania elektronów z cząsteczkami zawierającymi atomy C, Si, Ge, Sn oraz Ti.

  • Oko, obraz olejny na płótnie
    • Krzysztof Wróblewski
    2020

    Krzysztof Wróblewski w 1992 roku rozpoczął komponowanie symetrycznych obrazów składających się z realistycznych i abstrakcyjnych powierzchni. Połowę obrazu stanowią zawsze układy trójkątów. Relacje pomiędzy realizmem i abstrakcją oraz współzależność malarstwa i fotografii są kluczowymi zagadnieniami w jego twórczości. Jego prace często tworzą cykle tematyczne. Obraz pt. Oko prezentowany na 11. Charytatywnej Aukcji Sztuki Współczesnej Aperio należy do jednego z tych cyklów i jest charakterystyczny dla twórczości artysty.

  • Określenie przyczyn korozji śrub napędowych ORP Drużno.
    • Krzysztof Żakowski
    • Stefan Krakowiak
    2020

    Przedmiotem ekspertyzy było określenie przyczyn korozji śrub napędowych na okręcie ORP Drużno oraz wskazanie zaleceń odnośnie ograniczenia czynników powodujących ich korozję.

  • On Applications of Elements Modelled by Fractional Derivatives in Circuit Theory
    • Jacek Gulgowski
    • Tomasz Stefański
    • Damian Trofimowicz
    2020 Full text ENERGIES

    In this paper, concepts of fractional-order (FO) derivatives are reviewed and discussed with regard to element models applied in the circuit theory. The properties of FO derivatives required for the circuit-level modeling are formulated. Potential problems related to the generalization of transmission-line equations with the use of FO derivatives are presented. It is demonstrated that some formulations of FO derivatives have limited applicability in the circuit theory. Out of the most popular approaches considered in this paper, only the Grünwald–Letnikov and Marchaud definitions (which are actually equivalent) satisfy the semigroup property and are naturally representable in the phasor domain. The generalization of this concept, i.e., the two-sided fractional Ortigueira–Machado derivative, satisfies the semigroup property, but its phasor representation is less natural. Other ideas (including the Riemann–Liouville and Caputo derivatives—with a finite or an infinite base point) seem to have limited applicability.

  • On Applications of Fractional Derivatives in Circuit Theory
    • Jacek Gulgowski
    • Tomasz Stefański
    2020

    In this paper, concepts of fractional-order (FO) derivatives are discussed from the point of view of applications in the circuit theory. The properties of FO derivatives required for the circuit-level modelling are formulated. Potential problems related to the generalization of transmission line equations with the use of FO derivatives are presented. It is demonstrated that some of formulations of the FO derivatives have limited applicability in the circuit theory. That is, the Riemann-Liouville and Caputo derivatives with finite base point have a limited applicability whereas the Grünwald-Letnikov and Marchaud derivatives lead to reasonable results of the circuit-level modelling.

  • On Applications of Fractional Derivatives in Electromagnetic Theory
    • Jacek Gulgowski
    • Tomasz Stefański
    2020 Full text

    In this paper, concepts of fractional-order (FO) derivatives are analysed from the point of view of applications in the electromagnetic theory. The mathematical problems related to the FO generalization of Maxwell's equations are investigated. The most popular formulations of the fractional derivatives, i.e., Riemann-Liouville, Caputo, Grünwald-Letnikov and Marchaud definitions, are considered. Properties of these derivatives are evaluated. It is demonstrated that some of formulations of the FO derivatives have limited applicability in the electromagnetic theory. That is, the Riemann-Liouville and Caputo derivatives with finite base point have a limited applicability whereas the Grünwald-Letnikov and Marchaud derivatives lead to reasonable generalizations of Maxwell's equations.

  • On coertia and inertia in aspects of Natanson’s nonlinear extended thermodynamics
    • Janusz Badur
    • Paweł Ziółkowski
    • Tomasz Kowalczyk
    • Sylwia Gotzman
    • Daniel Sławiński
    • Tomasz Ochrymiuk
    • Marcin Daniel Lemański
    • Rafał Hyrzyński
    • Bartosz Kraszewski
    • Mateusz Bryk
    • Michał Stajnke
    • Piotr Józef Ziółkowski
    2020 Full text

    In this article, the previously underrepresented contributions of Natanson to the field of thermodynamics have been presented. In order to identify a source of irreversibility at Nature, Natanson introduced the concept of Coertia, which is similar to inertia. Natanson’s Coertia is a fundamental property of space that is responsible for every irreversible phenomena in matter, as well as in the electromagnetic and gravitational fields. We focus on the mathematical reconstruction of a few of his principal ideas that until now have been neglected by the literature. To set these ideas in proper epistemological order, we thought it would be valuable to first revalue and reconstruct some missing parts of the proceedings process by Ladislavus Natanson constructed their thermodynamics. We also aimed to present Natanson’s achievements against the background of modern continuum mechanics, exemplifying old but still relevant approaches. We propose that Natanson’s ideas were ahead of their time by about one century. Give that scientist was educated in the scientific royal way: chemistry, through mechanic of solid and fluid, thermodynamics, electro-chemistry, electrodynamics, early quantum and relativistic mechanics, we can closely compare their conceptions and solutions. Natanson was in strong opposition with Newtonian mechanisms, the Maupertuis least action principle formed the basis of his activities, which they were developing as a sum of elementary quantum actions.

  • On Computationally-Efficient Reference Design Acquisition for Reduced-Cost Constrained Modeling and Re-Design of Compact Microwave Passives
    • Sławomir Kozieł
    • Anna Pietrenko-Dąbrowska
    2020 Full text IEEE Access

    Full-wave electromagnetic (EM) analysis has been playing a major role in the design of microwave components for the last few decades. In particular, EM tools allow for accurate evaluation of electrical performance of miniaturized structures where strong cross-coupling effects cannot be adequately quantified using equivalent network models. However, EM-based design procedures (parametric optimization, statistical analysis) generate considerable computational expenses. These can be mitigated using fast surrogate models, yet their construction is hindered by the curse of dimensionality but also the utility requirements: a practically useful model needs to cover sufficiently broad ranges of geometry/material parameters as well as operating conditions. The recently proposed constrained modeling methods—both forward and inverse—work around the above issues by setting up the surrogate only in the relevant regions of the parameter space, i.e., containing designs that are of high quality with respect to the assumed performance measures. The model domain is established using pre-optimized sets of reference points. The high cost of generating such designs may significantly diminish the computational savings achieved by operating in confined domains. This paper discusses a technique for fast reference design acquisition, involving inverse gradients, and expedited local refinement aided by the response feature technology. The presented approach is validated using a branch-line coupler and miniaturized rat-race coupler. It is also demonstrated to considerably reduce the cost of constructing performance-driven surrogates as well as setting up efficient procedures for fast geometry scaling of microwave components.

  • On description of periodic magnetosonic perturbations in a quasi-isentropic plasma with mechanical and thermal losses and electrical resistivity
    • Anna Perelomova
    2020 Full text PHYSICS OF PLASMAS

    Magnetosonic periodic perturbations in a uniform and infinite plasma model are considered. Damping due to compressional viscosity, electrical resistivity, and thermal conduction are taken into account, as well as some heating–cooling function, which may destroy the isentropicity of wave perturbations. The wave vector forms arbitrary angle h with the equilibrium straight magnetic field, and all perturbations are functions of time and longitudinal coordinate. Variable h and plasma- b bring essential difficulties in the description of magnetosonic perturbations, which may be fast or slow. Wave damping of each kind depends differently on h and plasma- b . Longitudinal velocity, which is periodic at any distance from an exciter, is analytically constructed. It approximates the exact solution with satisfactory accuracy.

  • On design and analysis of flow characteristics of the last stage of gas-steam turbine
    • Stanisław Głuch
    • Paweł Ziółkowski
    • Łukasz Witanowski
    • Michał Stjanke
    • Piotr Józef Ziółkowski
    • Janusz Badur
    2020 Full text

    Research regarding blade design and analysis of flow have been conducted for over a century. Meanwhile new concepts and design approaches were created and improved. Advancements in information technologies allowed to introduce computational fluid dynamics (CFD) and computational flow mechanics (CFM). Currently a combination of mentioned methods is used for design of turbine blades. These methods enabled us to improve flow efficiency and strength of turbine blades. This paper relates to a new type turbine which is in the phase of theoretical analysis, because the working fluid is a mixture of steam and gas generated in wet combustion chamber. Conception of this cycle and thermodynamic calculations are presented in previous papers, therefore the main aim of this article is design and analysis of flow characteristics of the last stage of gas-steam turbine. When creating the spatial model, the atlas of profiles of reaction turbine steps was used. In this paper results of CFD calculations of twisting of the last stage are presented. Blades geometry and the computational mesh are also presented. Triangles of velocity for selected dividing sections are presented. It is worth noting that the velocity along the pitch diameter varies greatly. Near the root it shows an action triangle, on the other hand, near the tip it presents a reaction type of triangle. Velocity fields and pressure fields show the flow characteristics of the last stage of gas-steam turbine. The net efficiency of the cycle is estimated as 54.35% regarding to enthalpy drop, however, the net efficiency taking into account the mechanical power determined from the stage theory is equal 52.61%.

  • On DoA estimation for rotating arrays using stochastic maximum likelihood approach
    • Michał Meller
    • Kamil Stawiarski
    2020 Full text IEEE TRANSACTIONS ON SIGNAL PROCESSING

    The flexibility needed to construct DoA estimators that can be used with rotating arrays subject to rapid variations of the signal frequency is offered by the stochastic maximum likelihood approach. Using a combination of analytic methods and Monte Carlo simulations, we show that for low and moderate source correlations the stochastic maximum likelihood estimator that assumes noncorrelated sources has accuracy comparable to the estimator that includes the correlation coefficient as one of the parameters. We propose several fast approximations of the stochastic maximum likelihood estimator and compare their accuracy with the Cramer-Rao lower bound. We also discuss the model order selection problem for the binary- and multiple-hypotheses cases.

  • On Dynamic Extension of a Local Material Symmetry Group for Micropolar Media
    • Victor Eremeev
    • Violetta Konopińska-Zmysłowska
    2020 Full text Symmetry-Basel

    For micropolar media we present a new definition of the local material symmetry group considering invariant properties of the both kinetic energy and strain energy density under changes of a reference placement. Unlike simple (Cauchy) materials, micropolar media can be characterized through two kinematically independent fields, that are translation vector and orthogonal microrotation tensor. In other words, in micropolar continua we have six degrees of freedom (DOF) that are three DOFs for translations and three DOFs for rotations. So the corresponding kinetic energy density nontrivially depends on linear and angular velocity. Here we define the local material symmetry group as a set of ordered triples of tensors which keep both kinetic energy density and strain energy density unchanged during the related change of a reference placement. The triples were obtained using transformation rules of strain measures and microinertia tensors under replacement of a reference placement. From the physical point of view, the local material symmetry group consists of such density-preserving transformations of a reference placement, that cannot be experimentally detected. So the constitutive relations become invariant under such transformations. Knowing a priori a material’s symmetry, one can establish a simplified form of constitutive relations. In particular, the number of independent arguments in constitutive relations could be significantly reduced.

  • On Effective Bending Stiffness of a Laminate Nanoplate Considering Steigmann–Ogden Surface Elasticity
    • Victor Eremeev
    • Tomasz Wiczenbach
    2020 Full text Applied Sciences-Basel

    As at the nanoscale the surface-to-volume ratio may be comparable with any characteristic length, while the material properties may essentially depend on surface/interface energy properties. In order to get effective material properties at the nanoscale, one can use various generalized models of continuum. In particular, within the framework of continuum mechanics, the surface elasticity is applied to the modelling of surface-related phenomena. In this paper, we derive an expression for the effective bending stiffness of a laminate plate, considering the Steigmann–Ogden surface elasticity. To this end, we consider plane bending deformations and utilize the through-the-thickness integration procedure. As a result, the calculated elastic bending stiffness depends on lamina thickness and on bulk and surface elastic moduli. The obtained expression could be useful for the description of the bending of multilayered thin films.

  • On homotopies of morphisms and admissible mappings
    • Zdzisław Dzedzej
    • Tomasz Gzella
    2020 Full text Journal of Fixed Point Theory and Applications

    The notion of homotopy in the category of morphisms introduced by G´orniewicz and Granas is proved to be equivalence relation which was not clear for years. Some simple properties are proved and a coincidence point index is described.

  • On Inadequacy of Sequential Design of Experiments for Performance-Driven Surrogate Modeling of Antenna Input Characteristics
    • Anna Pietrenko-Dąbrowska
    • Sławomir Kozieł
    2020 Full text IEEE Access

    Design of contemporary antennas necessarily involves electromagnetic (EM) simulation tools. Their employment is imperative to ensure evaluation reliability but also to carry out the design process itself, especially, the adjustment of antenna dimensions. For the latter, traditionally used parameter sweeping is more and more often replaced by rigorous numerical optimization, which entails considerable computational expenses, sometimes prohibitive. A potentially attractive way of expediting the simulation-based design procedures is the replacement of expensive EM analysis by fast surrogate models (or metamodels). Unfortunately, due to the curse of dimensionality and considerable nonlinearity of antenna characteristics, applicability of conventional modeling methods is limited to structures described by small numbers of parameters within narrow ranges thereof. A recently proposed nested kriging technique works around these issues by allocating the surrogate model domain within the regions containing designs that are of high quality with respect to the selected performance figures. This paper investigates whether sequential design of experiments (DoE) is capable of enhancing the modeling accuracy over one-shot space-filling data sampling originally implemented in the nested kriging framework. Numerical verification carried out for two microstrip antennas indicates that no noticeable benefits can be achieved, which contradicts the common-sense expectations. This result can be explained by a particular geometry of the confined domain of the performance-driven surrogate. As this set consists of nearly-optimum designs, the average nonlinearity of the antenna responses therein is almost location independent, therefore optimum training data allocation should be close to uniform. This is indeed corroborated by our experiments.

  • On instabilities and post-buckling of piezomagnetic and flexomagnetic nanostructures
    • Mohammad Malikan
    • Nikolay S. Uglov
    • Victor Eremeev
    2020 Full text INTERNATIONAL JOURNAL OF ENGINEERING SCIENCE

    We focus on the mechanical strength of piezomagnetic beam-like nanosize sensors during post-buckling. An effective flexomagnetic property is also taken into account. The modelled sensor is selected to be a Euler-Bernoulli type beam. Long-range interactions between atoms result in a mathematical model based on the nonlocal strain gradient elasticity approach (NSGT). Due to possible large deformations within a post-buckling phenomenon, the resultant equations are essentially nonlinear. We establish the results using an analytical approach, including a variety of boundary conditions. We visualize the effective response of the designed sensor for several key components. It was obtained that the flexomagnetic effect is meaningful for less flexible boundary conditions. Besides, it was found that the failure originated from post-buckling occurs sooner if the numerical amounts of nonlocal parameter and the strain gradient one are respectively so small and exceedingly large.

  • On Nonlinear Bending Study of a Piezo-Flexomagnetic Nanobeam Based on an Analytical-Numerical Solution
    • Mohammad Malikan
    • Victor Eremeev
    2020 Full text Nanomaterials

    Among various magneto-elastic phenomena, flexomagnetic (FM) coupling can be defined as a dependence between strain gradient and magnetic polarization and, contrariwise, elastic strain and magnetic field gradient. This feature is a higher-order one than piezomagnetic, which is the magnetic response to strain. At the nanoscale, where large strain gradients are expected, the FM effect is significant and could be even dominant. In this article, we develop a model of a simultaneously coupled piezomagnetic–flexomagnetic nanosized Euler–Bernoulli beam and solve the corresponding problems. In order to evaluate the FM on the nanoscale, the well-known nonlocal model of strain gradient (NSGT) is implemented, by which the nanosize beam can be transferred into a continuum framework. To access the equations of nonlinear bending, we use the variational formulation. Converting the nonlinear system of differential equations into algebraic ones makes the solution simpler. This is performed by the Galerkin weighted residual method (GWRM) for three conditions of ends, that is to say clamp, free, and pinned (simply supported). Then, the system of nonlinear algebraic equations is solved on the basis of the Newton–Raphson iteration technique (NRT) which brings about numerical values of nonlinear deflections. We discovered that the FM effect causes the reduction in deflections in the piezo-flexomagnetic nanobeam.