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  • Nonlinear free and forced vibrations of a dielectric elastomer-based microcantilever for atomic force microscopy
    • Amin Alibakhshi
    • Shahriar Dastjerdi
    • Mohammad Malikan
    • Victor Eremeev
    2022 Pełny tekst CONTINUUM MECHANICS AND THERMODYNAMICS

    The majority of atomic force microcode (AFM) probes work based on piezoelectric actuation. However, some undesirable phenomena such as creep and hysteresis may appear in the piezoelectric actuators that limit their applications. This paper proposes a novel AFM probe based on dielectric elastomer actuators (DEAs). The DE is modeled via the use of a hyperelastic Cosserat model. Size effects and geometric nonlinearity are included utilizing the modified couple stress theory and the von-Kármán strains. A non-contact interaction condition is adopted for AFM, which is taken into account via the van der Waals force. Governing equations are derived employing Hamilton’s principle, and a reduced model is obtained using an extended Galerkin scheme. The free vibration of the system is formulated when a static voltage is applied to the elastomer. The forced vibration is then formulated when the system is under a combination of static and dynamic voltages. The ordinary differential equations of the free and forced vibrations are numerically and analytically solved by the backward differentiation method and multiple time scales method, respectively. Results are presented in time histories, phase portraits, Poincaré maps, fast Fourier transforms, and frequency amplitude curves. Overall, the obtained information displays that the system undergoes quasiperiodic and periodic motions. Moreover, the resonant response of the DE-based AFM is softening-type.

  • Nonlinear material identification of heterogeneous isogeometric Kirchhoff–Love shells
    • Bartosz Borzeszkowski
    • Izabela Lubowiecka
    • Roger Sauer
    2022 Pełny tekst COMPUTER METHODS IN APPLIED MECHANICS AND ENGINEERING

    This work presents a Finite Element Model Updating inverse methodology for reconstructing heterogeneous materialdistributions based on an efficient isogeometric shell formulation. It uses nonlinear hyperelastic material models suitable fordescribing incompressible material behavior as well as initially curved shells. The material distribution is discretized by bilinearelements such that the nodal values are the design variables to be identified. Independent FE analysis and material discretization,as well as flexible incorporation of experimental data, offer high robustness and control. Three elementary test cases and oneapplication example, which exhibit large deformations and different challenges, are considered: uniaxial tension, pure bending,sheet inflation, and abdominal wall pressurization. Experiment-like results are generated from high-resolution simulations withthe subsequent addition of up to 4% noise. Local optimization based on the trust-region approach is used. The results showthat with a sufficient number of experimental measurements, design variables and analysis elements, the algorithm is capableto reconstruct material distributions with high precision even in the presence of large noise. The proposed formulation isvery general, facilitating its extension to other material models, optimization algorithms and meshing approaches. Adaptedmaterial discretizations allow for an efficient and accurate reconstruction of material discontinuities by avoiding overfitting dueto superfluous design variables. For increased computational efficiency, the analytical sensitivities and Jacobians are provided.

  • Nonlinear strain gradient and micromorphic one-dimensional elastic continua: Comparison through strong ellipticity conditions
    • Victor Eremeev
    • Emanuele Reccia
    2022 Pełny tekst MECHANICS RESEARCH COMMUNICATIONS

    We discuss the strong ellipticity (SE) conditions for strain gradient and micromorphic continua considering them as an enhancement of a simple nonlinearly elastic material called in the following primary material. Recently both models are widely used for description of material behavior of beam-lattice metamaterials which may possess various types of material instabilities. We analyze how a possible loss of SE results in the behavior of enhanced models. We shown that SE conditions for a micromorphic medium is more restrictive than for its gradient counterpart. On the other hand we see that a violation of SE for a primary material affects solutions within enhanced models even if the SE conditions are fulfilled for them.

  • NONLINEAR VIBRATION ANALYSIS OF BEAM AND PLATE WITH CLOSED CRACK: A REVIEW
    • Samrawit Alemayehu Tewelde
    • Marek Krawczuk
    2022 Pełny tekst Acta Mechanica et Automatica

    The effect of nonlinearity is high sensitivity in damage detection, especially for closed cracks and delamination. This review illustrates the results of several researchers dealing with nonlinear effects caused by the closure of cracks in the structure, i.e., beam and plate structures. Early detection of damage is an important aspect for the structure and, therefore, continuous progress is being made in developing new and effective methods that use nonlinear effects for early detection of damage and barely visible cracks, i.e., closed cracks and delamination, as well as for the determination of crack size and location. After analysing various methods, the merits, drawbacks and prospects of a number of nonlinear vibration methods for structural damage detection are discussed, and recommendations are made for future researchers

  • Nonlocal Models of Plates and Shells with Applications in Micro- and Nanomechanics
    • Mohammad Malikan
    2022 Pełny tekst

    Nowadays, the use of small-scale structures in micro/nanomachines has become more and more widespread. The most important applications of such small-sized parts are in micro-electro-mechanical systems (MEMS) as well as nano-electro-mechanical systems (NEMS) as actuators, sensors, energy harvesters. For example, nanosensors are nanoscale devices that measure physical quantities and convert these to signals that can be detected and analyzed. On the applications of micro/nanosensors in civil engineering, one can state that nanosensors can be developed and used in construction to monitor and/or control the environmental conditions and the materials/structures' performance. As an example, nanosensors can be used to monitor concrete corrosion and micro-cracking. The smart sensor can also be employed for structural health monitoring in bridges and other structures. In this regard, understanding the mechanical response of such structures in various environmental and physical situations is seriously required. For the design and modelling of such a device, one can use various approaches. First, we mention straightforward experiments which need special equipment and result in high costs. Second, molecular dynamics could be used, which requires a lot of computational efforts, in general. Moreover, this method cannot be implemented for all types of nanostructures. Finally, the application of continuum models properly modified for modelling materials and structures at small scales is worth mentioning. Among various enhancements of classic mechanics of continua and structures, we mention the non-local approach related to the description of long-range interactions. In what follows, we apply the third technique based on non-local models and corresponding modelling to thin-walled structures as principal elements of MEMS and NEMS. Moreover, we consider the coupling between mechanical and electromagnetic fields. So this dissertation is based on this approach. Using it, the mechanical behavior of the MEMS and NEMS has been predicted.

  • Nonlocalized thermal behavior of rotating micromachined beams under dynamic and thermodynamic loads
    • Ahmed E. Abouelregal
    • Hamid M. Sedighi
    • Mohammad Malikan
    • Victor Eremeev
    2022 Pełny tekst ZAMM-Zeitschrift fur Angewandte Mathematik und Mechanik

    Rotating micromachined beams are one of the most practical devices with several applications from power generation to aerospace industries. Moreover, recent advances in micromachining technology have led to huge interests in fabricating miniature turbines, gyroscopes and microsensors thanks to their high quality/reliability performances. To this end, this article is organized to examine the axial dynamic reaction of a rotating thermoelastic nanobeam under a constant-velocity moving load. Using Eringen’s nonlocal elasticity in conjunction with Euler–Bernoulli theory and Hamilton's principle, the governing equations are derived. It is assumed that the nanobeam is affected by thermal load and the boundary condition is simply supported. The Laplace transform approach is employed to solve the partial differential equations. A numerical example is presented to analyze the effects of the nonlocal parameter, rotation speed and velocity of the static moving load on the dynamic behavior of the system. The numerical results are graphically illustrated and analyzed to recognize the variations of field variables. Finally, in some special cases, our results are compared to those reported in the literature to demonstrate the reliability of the current model.

  • Non-Perfect Propagation of Information to a Noisy Environment with Self-Evolution
    • Piotr Mironowicz
    • Paweł Horodecki
    • Ryszard Horodecki
    2022 Pełny tekst ENTROPY

    We study the non-perfect propagation of information for evolving a low-dimensional environment that includes self-evolution as well as noisy initial states and analyse the interrelations between the degree of objectivization and environment parameters. In particular, we consider an analytical model of three interacting qubits and derive its objectivity parameters. The numerical analysis shows that the quality of the spectrum broadcast structure formed during the interaction may exhibit non-monotonicity both in the speed of self-dynamics of the environment as well as its mixedness. The former effect is particularly strong, showing that—considering part of the environment as a measurement apparatus—an increase of the external magnetic field acting on the environment may turn the vague measurement into close to ideal. The above effects suggest that quantum objectivity may appear after increasing the dynamics of the environment, although not with respect to the pointer basis, but some other, which we call the generalized pointer or indicator basis. Furthermore, it seems also that, when the objectivity is poor, it may be improved, at least by some amount, by increasing the thermal noise. We provide further evidence of this by analysing the upper bounds on distance to the set of states representing perfect objectivity in the case of a higher number of qubits.

  • Non-volatile molecular composition and discrimination of single grape white of chardonnay, riesling, sauvignon blanc and silvaner using untargeted GC–MS analysis
    • Bekzod Khakimov
    • Inal Bakhytkyzy
    • Carsten Fauhl-Hassek,
    • Søren Balling Engelsen
    2022 FOOD CHEMISTRY

    This study developed and applied a GC–MS method aiming at molecular fingerprinting of 120 commercial single grape white wines (Chardonnay, Riesling, Sauvignon Blanc and Silvaner) for possible authentication according to grape variety. The method allowed detection of 372 peaks and tentative identification of 146 metabolites including alcohols, organic acids, esters, amino acids and sugars. The grape variety effect explained 8.3% of the total metabolite variation. Univariate tests showed two-thirds of the metabolites being different between grape varieties. Partial least squares-discriminant analysis based classification models were developed for each grape variety and a panel of classifiers (42 metabolites) was established. All the classification models for grape variety showed a high certainty (>91%) for an independent test set. Riesling contained the highest relative concentrations of sugars and organic acids, while concentrations of hydroxytyrosol and gallic acid, common antioxidants in wine, decreased in the order of Chardonnay > Riesling > Sauvignon Blanc > Silvaner.

  • Notch fatigue analysis and life assessment using an energy field intensity approach in 7050-T6 aluminium alloy under bending-torsion loading
    • Ricardo Branco
    • José Domingos Costa
    • L.p. Borrego
    • Wojciech Macek
    • Filippo Berto
    2022 Pełny tekst INTERNATIONAL JOURNAL OF FATIGUE

    This paper studies the fatigue crack initiation and fatigue crack propagation of notched cylindrical bars made of 7050-T6 aluminium alloy subjected to multiaxial bending-torsion loading. The sites of crack initiation and the angles of crack initiation were successfully predicted from the distribution of the first principal stress at the notch surface. Fatigue crack initiation lives were computed through the new concept of energy field intensity formalised in a linear-elastic framework along with a local stress-strain model for notch plasticity analysis. Regardless of the model used to compute the cyclic response at the geometric discontinuity, the fatigue life predictions were in good agreement with the experimental observations.

  • Novel amides of mycophenolic acid and some heterocyclic derivatives as immunosuppressive agents
    • Juliusz Walczak
    • Dorota Iwaszkiewicz-Grześ
    • Michalina Ziomkowska
    • Magdalena Śliwka-Kaszyńska
    • Mateusz Daśko
    • Piotr Trzonkowski
    • Grzegorz Cholewiński
    2022 Pełny tekst JOURNAL OF ENZYME INHIBITION AND MEDICINAL CHEMISTRY

    The group of new amide derivatives of mycophenolic acid (MPA) and selected heterocyclic amines was synthesised as potential immunosuppressive agents functioning as inosine-5'-monophosphate dehydrogenase (IMPDH) uncompetitive inhibitors. The synthesis employed uronium-type activating system (TBTU/HOBt/DIPEA) while or phosphonic acid anhydride method (T3P/Py) facilitating amides to be obtained in moderate to excellent yields without the need of phenolic group protection. Most of optimised protocols did not require complicated reaction work-ups, including chromatographic, solvent- consuming methods. The biological activity assay was performed on the T-Jurkat cell line and peripheral mononuclear blood cells (PBMCs) which are both dedicated for antiproliferative activity determination. Each of designed derivatives was characterised by reduced cytotoxicity and benzoxazole analogue revealed the most promising activity. Subsequently, an observed structure-activity relationship was discussed.

  • Novel Binary Mixtures of Alkanolamine Based Deep Eutectic Solvents with Water—Thermodynamic Calculation and Correlation of Crucial Physicochemical Properties
    • Bartosz Nowosielski
    • Marzena Jamrógiewicz
    • Justyna Łuczak
    • Dorota Warmińska
    2022 Pełny tekst MOLECULES

    This paper demonstrates the assessment of physicochemical and thermodynamic properties of aqueous solutions of novel deep eutectic solvent (DES) built of tetrabutylammonium chloride and 3-amino-1-propanol or tetrabutylammonium bromide and 3-amino-1-propanol or 2-(methylamino)ethanol or 2-(butylamino)ethanol. Densities, speeds of sound, refractive indices, and viscosities for both pure and aqueous mixtures of DES were investigated over the entire range of compositions at atmospheric pressure and T = (293.15 - 313.15) K. It was concluded that the experimental data were successfully fitted using the Jouyban–Acree model with respect to the concentration. Obtained results showed that this mathematical equation is an accurate correlation for the prediction of aqueous DES properties. Key physicochemical properties of the mixtures—such as excess molar volumes, excess isentropic compressibilities, deviations in viscosity, and deviations in refractive indices—were calculated and correlated by the Redlich–Kister equation with temperaturedependent parameters. The non-ideal behavior of the studied systems were also evaluated by using the Prigogine−Flory−Patterson theory and the results were interpreted in terms of interactions between the mixture components.

  • Novel chalcone-derived pyrazoles as potential therapeutic agents for the treatment of non-small cell lung cancer
    • Natalia Maciejewska
    • Mateusz Olszewski
    • Jakub Jurasz
    • Marcin Serocki
    • Maria Dzierżyńska
    • Katarzyna Cekała
    • Ewa Wieczerzak
    • Maciej Bagiński
    2022 Pełny tekst Scientific Reports

    Lung cancer is considered to account for approximately one-fifth of all malignant tumor-related deaths worldwide and is therefore one of the most lethal malignancies. Pyrazole scaffold possesses a wide range of biological and pharmacological activities, which play important roles in medicinal chemistry. The present study reports the synthesis and in vitro biological characterization of nine pyrazoles derived from chalcones as potential anticancer agents for non-small cell lung cancer A-549, H226, and H460 cell lines. Most of the compounds efficiently inhibited the growth of all the tested cancer cell lines at micromolar concentrations. One of the most active compounds (PCH-1) was further evaluated for its effect on cell cycle distribution, apoptosis, migration, epithelial–mesenchymal transition, and oxidative stress. Furthermore, studies on the mechanism of action revealed that PCH-1 disrupts microtubule assembly, leading to cancer cell death. Molecular modeling studies confirmed the potent interaction of PCH-1 with the vinblastine binding site on tubulin. Overall, this study provides novel opportunities to identify anticancer agents in the pyrazole series.

  • Novel composite of Zn/Ti-layered double hydroxide coupled with MXene for the efficient photocatalytic degradation of pharmaceuticals
    • Anna Grzegórska
    • Izabela Wysocka
    • Paweł Głuchowski
    • Jacek Ryl
    • Jakub Karczewski
    • Anna Zielińska-Jurek
    2022 Pełny tekst CHEMOSPHERE

    In the present study, a hybrid photocatalyst of Zn/Ti layered double hydroxide (LDH) coupled with MXene – Ti3C2 was synthesized for the first time and applied in photocatalytic degradation of acetaminophen and ibuprofen, two commonly present in the natural environment and prone to accumulate in the aquatic ecosystem pharmaceuticals. The effect of MXene content (0.5 wt%, 2.5 wt%, and 5 wt%) on the photocatalytic activity of LDH/MXene composite was investigated. The composite of LDH/MXene containing 2.5 wt% of MXene revealed the highest photocatalytic activity in the degradation of acetaminophen (100% within 40 minutes) and ibuprofen (99.7% within 60 minutes). Furthermore, an improvement in acetaminophen and ibuprofen mineralization was observed for the composite material. Meanwhile, the introduction of interfering ions (Na+, Ca2+, Mg2+, Cl-, SO42-) in the model seawater did not affect the removal efficiency of both pharmaceuticals. The photocatalytic experiment performed in the four subsequent cycles, as well as FTIR, TEM, and XPS analyses after the photodegradation process confirmed the excellent stability and reusability of the prepared composite material. In order to evaluate the effect of various reactive oxidizing species (ROS) on the photocatalytic process, the trapping experiment was applied. It was noticed that •O2- had the main contribution in photocatalytic degradation of acetaminophen, while •OH and h+ mainly affected the degradation of ibuprofen. Finally, based on the results of Mott Schottky analysis, bandgap calculation, and ROS trapping experiment, the possible mechanism for pharmaceuticals degradation was proposed. This research illustrates the feasibility and novelty of the treatment of pharmaceuticals by LDH/MXene composites, implying that MXene plays a significant role in the electron-hole separation and thus high photocatalytic activity.

  • Novel Interpolation Method of Multi-DFT-Bins for Frequency Estimation of Signal with Parameter Step Change
    • Kai Wang
    • Shan Liu
    • Lanlan Wang
    • Janusz Smulko
    • He Wen
    2022 Pełny tekst IEEE TRANSACTIONS ON INSTRUMENTATION AND MEASUREMENT

    The IpDFT(Interpolation Discrete Fourier Trans-form) method is one of the most commonly used non-parametric methods. However, when a parameter (frequency, amplitude or phase) step changes in the DFT period, the DFT coefficients will be distorted seriously, resulting in the large estimation error of the IpDFT method. Hence, it is a key challenge to find an IpDFT method, which not only can eliminate the effect of the step-changed symbol, but also can sufficiently eliminate the fence effect and the spectrum leakage. In this paper, an IpDFT based method is proposed to estimate the frequency of the single tone signal with the step-changed parameters in the sampling signal sequence. The relationship between the DFT bins and the step changed parameters is given by several linear equations. At most six different DFT bins are used to eliminate the effect of symbol.

  • Novel Low-Loss Substrates for 5G Applications
    • Krzysztof Babicki
    • Adam Lamęcki
    • Michał Mrozowski
    • Michał Baranowski
    • Anna Wroblewska
    • Mariusz Zdrojek
    • Bartlomiej Salski
    • Jerzy Krupka
    2022

    This paper presents a feasibility study of a new type of microwave low-loss dielectric substrates for 5G network applications. The new substrate materials are composites of polypropylene and high-dielectric-constant micro-ceramics. This combination is expected to form a very low-loss dielectric material at low fabrication cost. Two substrate samples with different dielectric properties are fabricated and their characteristics at microwave frequencies are investigated in this paper. The investigation covers two scenarios for the metallization of the substrates to form printed circuit boards. The dielectric properties of the materials are measured using the split post dielectric resonator technique. Furthermore, the quality of the materials is experimentally verified though the design, fabrication, and measurement of simple resonator structures

  • Novel method of estimation of inertial and dissipative parameters of a railway pantograph model
    • Andrzej Wilk
    • Len Gelman
    • Sławomir Judek
    • Krzysztof Karwowski
    • Mirosław Mizan
    • Tadeusz Maciołek
    • Miroslaw Lewandowski
    • Aleksander Jakubowski
    • Karolina Klimowska
    2022 Pełny tekst VEHICLE SYSTEM DYNAMICS

    An increase in electric railway vehicles service velocity requires that correct interaction between the pantograph and the catenary is ensured. This implies the need for developing mathematical models of pantographs and catenaries and determining their parameters. The article presents a method to determine parameters of mechanical joints of a railway pantograph based on analysis of pantograph subassemblies in swinging motion. The experimental tests consisted in disassembling the pantograph and creating partial subassemblies which were then analysed with respect to their damped linear or angular oscillations. The simulation analysis required developing, in CAD, 3D models of individual pantograph parts and their subassemblies. Defined were joints between particular elements, which represent of real pantograph structure. The inertia parameters of the model were determined, based on structural characteristics and physical properties of materials, used for manufacturing individual pantograph elements, and then verified experimentally. The dissipative parameters of the mechanical joints were calculated iteratively. The model of complete pantograph assembly was also subject to verification and in this case, good convergence between simulation and experiment results was achieved. The obtained parameter values can be used in simulation models of other railway pantographs having a similar structure.

  • Novel Nonlinear High Order Technologies for Damage Diagnosis of Complex Assets
    • Tomasz Ciszewski
    • Len Gelman
    • Andrew Ball
    2022 Pełny tekst Electronics

    For the first time worldwide, innovative techniques, generic non-linear higher-order unnormalized cross-correlations of spectral moduli, for the diagnosis of complex assets, are proposed. The normalization of the proposed techniques is based on the absolute central moments, that have been proposed and widely investigated in mathematical works. The existing higher-order, crosscovariances of complex spectral components are not sufficiently effective. The novel technology is comprehensively experimentally validated for induction motor bearing diagnosis via motor current signals. Experimental results, provided by the proposed technique, confirmed high overall probabilities of correct diagnoses for bearings at early stages of damage development. The proposed diagnosis technology is compared with existing diagnosis technology, based on the triple cross-covariance of complex spectral components.

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

    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 Pełny tekst 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 Pełny tekst

    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 Pełny tekst 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 Pełny tekst 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 Pełny tekst

    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 Pełny tekst 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 Pełny tekst 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 Pełny tekst 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 Pełny tekst 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 Pełny tekst

    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 Pełny tekst 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 Pełny tekst 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 Pełny tekst 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 Pełny tekst 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 Pełny tekst 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 Pełny tekst 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 Pełny tekst 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 Pełny tekst

    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 Pełny tekst 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 Pełny tekst 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 Pełny tekst 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 Pełny tekst 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.