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Gdańsk University of Technology

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Publications from the year 2020

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  • THE EFFECT OF LOG SORTING STRATEGY ON THE FORECASTED LUMBER VALUE AFTER SAWING PINE WOOD
    • Piotr Taube
    • Kazimierz Orłowski
    • Daniel Chuchała
    • Jakub Sandak
    2020 Full text ACTA FACULTATIS XYLOLOGIAE ZVOLEN

    The optimal transformation path for the resource is determined by the quality of a log combined with its dimension. The commercial value of derived products is also closely connected with the size and extent of containing wood deficiencies. The results of studies with three diverse strategies for log sorting are presented in the paper. Resource assessment by a worker without extensive experience in sorting logs, the certified grading expert, and the automatic in-line system including optical scanner with dedicated software are compared. It was shown that the lack of experience of the person performing the sorting operation results in reducing the potential economic profits of a sawmill. On the contrary, the overall efficiency of the log conversion process is considerably improved by the automated sorting systems with scanners. Early identification of logs optimal for specific lumber production is assured by reducing the human errors and subjective evaluation. Both, the yield of produced timber and profits of the sawmill are directly affected this way. It was demonstrated that the log sorting rate performed by the scanner is four times higher in comparison to grading by the certified expert, as well as three times higher compared to employee with no experience. The finding that the volume of high-quality lumber of elevated value is the lowest in the case the log is sorted by a human was proved.

  • The effect of morphology and crystalline structure of Mo/MoO3 layers on photocatalytic degradation of water organic pollutants
    • Mariusz Szkoda
    • Konrad Trzciński
    • Andrzej Nowak
    • Maria Gazda
    • Mirosław Sawczak
    • Anna Lisowska-Oleksiak
    2020 Full text MATERIALS CHEMISTRY AND PHYSICS

    Molybdenum oxide layers were formed by anodization of the Mo metallic foil in a water/ethylene glycol-based electrolyte containing fluoride ions. The as-prepared, amorphous samples were annealed in air at different temperatures in a range from 100 �C to 700 �C. The crystal phase and morphology of anodized and annealed MoO3 layers were investigated using X-ray diffraction, Raman spectroscopy, and scanning electron microscopy. The photoactivity of obtained materials was tested during a photocatalytic process of methylene blue (MB) decomposition. The increase of annealing temperature led to the production of films characterized by improved photocatalytic properties, with maximum photocatalytic efficiency observed for MoO3 annealed at 600 �C. The studies on the use of MoO3 as a photoelectrocatalyst for degradation of dye were performed. Furthermore, the photocatalytic activity of the MoO3 annealed at 600 �C was investigated during a photodegradation of diclofenac acting as a model pharmaceutical compound

  • The Effect of Posaconazole, Itraconazole and Voriconazole in the Culture Medium on Aspergillus fumigatus Triazole Resistance
    • Martyna Mroczyńska
    • Ewelina Kurzyk
    • Magdalena Śliwka-Kaszyńska
    • Urszula Nawrot,
    • Marta Adamik
    • Anna Brillowska-Dąbrowska
    2020 Full text Microorganisms

    Triazoles are the only compounds used as antibiotics in both medicine and agriculture. The presence of triazoles in the environment can contribute to the acquisition of azole resistance among isolates of Aspergillus fumigatus. The objective of this study was to investigate the effect of A. fumigatus exposure to triazoles on susceptibility to these compounds. Seventeen triazole-resistant and 21 triazole-sensitive A. fumigatus isolates were examined. The isolates were transferred 20 times on the Sabouraud medium supplemented with posaconazole, itraconazole or voriconazole, followed by five times on the medium not supplemented. The minimum inhibitory concentrations of antimycotics were examined according to the EUCAST broth microdilution method after the 20th transfer and also the 25th transfer. In addition, the expression levels of genes mdr1, mdr2, mdr3, atrF, cyp51A and cyp51B were determined. Cultivation of A. fumigatus on media supplemented with posaconazole, itraconazole and voriconazole resulted in the acquisition of resistance to the tested triazoles of all examined isolates. After recultivation on Sabouraud without azoles, most of the isolates lost their acquired resistance. The long-term use of triazole compounds in agriculture may result in the occurrence of triazole resistant A. fumigatus isolates in the environment, not only by induction or selection of mutations in the cyp51A gene, but also by contribution to changes in the gene expression.

  • The effectiveness of financial and economic regulation of land relations in the context of stimulating entrepreneurial activity in the regions of Ukraine
    • Uliana Vatamanyuk-Zelinska
    • Oleksandr Melnychenko
    2020 Full text Problems and Perspectives in Management

    Solving the problem of enhancing the efficiency of the financial and economic regulation of land relations contributes to the development of entrepreneurship in Ukraine. The purpose of the paper is to determine new incentives for encouraging entrepreneurial activity by increasing the efficiency of the financial and economic regulation of land relations by local governments. The study is based on applying the method for predicting amounts of local budget revenues in Ukraine from the land tax and lease fees through the use of communally owned land plots to stimulate entrepreneurial initiatives of the unemployed. In the process of research, the projected amounts of local budget revenues from financial transactions with plots of industrial lands in each region of Ukraine have been determined, taking into account the possibilities of leasing the lands, for which lease fees are covered by a one-time benefit provided to the unemployed for organizing entrepreneurial activity. It is proposed to determine the efficiency of the financial and economic regulation of land relations in the regions of Ukraine, applying indicators such as the use of industrial lands together with objects of lease located on them and the involvement of the unemployed from among the economically active population in entrepreneurial activity. To improve the efficiency of financial and economic regulation of land relations, local governments are proposed to establish the optimal proportion of amounts of borrowed resources, taking into account the need for their saving and rational use.

  • The effects of urban vehicle traffic on heavy metal contamination in road sweeping waste and bottom sediments of retention tanks
    • Nicole Nawrot
    • Ewa Wojciechowska
    • Shahabaldin Rezania
    • Jolanta Walkusz-miotk
    • Ksenia Pazdro
    2020 Full text SCIENCE OF THE TOTAL ENVIRONMENT

    Diffuse pollution formed during a surface runoff on paved surfaces is a source of heavy metals (HMs) of various origin. This research study indicates the connection between bottom sediments of retention tanks located on urban streams and road sweeping wastes (RSW) that migrate during surface runoff to the stormwater drainage systems with discharge to the retention tanks. Moreover, we test the primary sources of HMs in RSW by analysing the mechanical wastes (MW) produced by vehicles in order to track the relationship between car parts and HMs deposited in the retention tanks receiving the surface runoff from streets. To identify the origin ofHMs diverse source tracking approaches were used: statisticalmethods, Pb isotope ratios, and the flag element ratio approach.MWpresented a very highHMs content (max observed values inmg/kg d.w.: 10477-Zn, 3512-Cu, 412-Pb, 3.35-Cd, 226-Ni, and 633-Cr), while for RSWthe HMs content was similar to the bottom sediments. The total carcinogenic risk raises concerns due to the Cr content. The source of Zn was tyre wear and traffic. Ni, Cr, Fe, and Cd were correlated to Zn and shared a common/similar origin. PCA suggested that Cu features quasiindependent behaviour. The Pb isotopic ratios of RSWindicated Pb enrichment originating fromcoal combustion, while the gasoline and diesel source of Pb was excluded. The Pb isotopic ratios characteristic for MW were in within the following ranges: 1.152–1.165 (206Pb/207Pb), 2.050–2.085 (208Pb/206Pb), and 2.350–2.418 (208Pb/207Pb). The complex analysis of HMs origin confirmed the motorization origin of HMs: Zn, Cr, Ni, and Cd, except Pb (coal combustion as the main source) and Cu (non-uniform origin). The results of various source tracking methods were coherent, but Pb isotope ratios alone brought important information allowing to link Pb in sediments to the atmospheric deposition of coal combustion products.

  • The electrochemical determination of isatin at nanocrystalline boron-doped diamond electrodes: stress monitoring of animals
    • Michał Sobaszek
    • Siuzdak Katarzyna
    • Jacek Ryl
    • Robert Bogdanowicz
    • Greg N. Swain
    2020 SENSORS AND ACTUATORS B-CHEMICAL

    Ultra-thin nanocrystalline boron-doped diamond electrodes (B:NCD) were used for the electrochemical determination of isatin in dog urine samples using cyclic voltammetry and square wave voltammetry in a phosphate buffer saline, pH = 7.2. No additional modification or pretreatment of the electrode surface was required in this approach, being of high importance for the facile detection procedure. The increase of the peak current was linearly related to the raised concentration of isatin in phosphate buffer. The limit of isatin detection was equal to 0.2 µM and 3 µM for B:NCD and reference glassy carbon electrodes respectively. The relatively high current sensitivities of 1.32 μAcm-2 μM-1 were achieved thanks to the nanocrystalline diamond surface. We have demonstrated that isatin could be determined at B:NCD electrode in the complex urine matrix within the limit of detection having 1 μM along with sensitivity of 0.46 μAcm-2 μM-1 without pre-treatment procedure of the analyte

  • The electronic excited states of dichloromethane in the 5.8-10.8 eV energy range investigated by experimental and theoretical methods
    • E. Lange
    • Nykola C. Jones
    • Søren Hoffmann
    • Ana Lozano
    • S. Kumar
    • M Homem
    • Małgorzata Śmiałek-Telega
    • Denis Duflot
    • M. Brunger
    • Paulo Limão-Vieira
    2020 Full text JOURNAL OF QUANTITATIVE SPECTROSCOPY & RADIATIVE TRANSFER

    We present a comprehensive experimental high-resolution vacuum ultraviolet (VUV) photoabsorption spectrum of dichloromethane, CH 2 Cl 2 , with absolute cross sections determined for the full 5.8–10.8 eV energy-range. The calculations on the vertical excitation energies and oscillator strengths were performed using the equation-of-motion coupled cluster method, restricted to the single and double excitations level (EOM-CCSD), and were used to help analyse the valence and Rydberg structures in the photoab- sorption spectrum. The present spectrum additionally reveals several new features not previously re- ported in the literature, with particular reference to the valence σ∗C C l ( 10 a 1 ) ← n Cl ( 7 b 2 ) ( 1 1 B 2 ← ̃ X 1 A 1 ) and ( σ∗C C l ( 10 a 1 ) ← n Cl ( 9 a 1 ) + σ∗CH ( 11 a 1 ) ← n Cl ( 7 b 2 ) ) ( 1 1 A 1 ← ̃ X 1 A 1 ) transitions at 7.519 and 7.793 eV. A vibrational progression of the CCl 2 symmetric stretching, ν′ 3 , and CCl 2 scissoring, v ′ 4 ( a 1 ) , modes have also been assigned for the first time in the 7.4–8.6 eV energy range. The measured absolute photoabsorption cross sections have been used to calculate the photolysis lifetime of dichloromethane in the Earth’s atmo- sphere (0–50 km). Potential energy curves as a function of the C–Cl coordinate, for the four lowest-lying excited A ′ and A ′′ electronic states, have additionally been calculated at the EOM-CCSD level of theory.

  • The experience of movement in orbital space architecture: A narrative of weightlessness
    • Mosleh Ahmadi
    • Nomusa Makhubu
    2020 Full text Cogent Arts & Humanities

    Based upon a combination of architectural theories, the knowledge of space environment, and psychology of isolated and confined environments, this qualitative research aims to study orbital space settlement in a way to get the built space congenial to the human experience of movement. In this sense, sensors, self-propulsion or mechanical actuators, the inhabitant’s mental and visual capacity for movement, as well as the represented and imbedded movement in the built environment—including pictorial representation, kinetic formation, and the movement of natural factors—are variables. So far, most of the studies on counter-measures for minimizing stress, which are stumbling blocks to the architectural promenade, have been based on pre-launch training focusing on professional training and selection of astronauts, planning for their in-flight challenges, and protecting them from dangers. Meanwhile, if we want to promote the experience of architecture in the outer space, narratives of movement need to be enriched, because not all occupants are professional astronauts. One way to study this matter is through analyzing movement in the built space and then synthesizing the results to gain an overview of a spatial montage in which motor planning for movement and route navigation have been facilitated. Narrative, in this sense, is a proper method to investigate this context of design. Therefore, analysis has been framed in the shape of a taxonomy of movement in weightlessness. Through a qualitative investigation in Cupola Module, it has been thrown into relief that movement with regard to space has not been enriched as much as movement with regard to the form.

  • The geometry of free-standing titania nanotubes as a critical factor controlling their optical and photoelectrochemical performance
    • Jakub Wawrzyniak
    • Katarzyna Grochowska
    • Jakub Karczewski
    • Piotr Kupracz
    • Jacek Ryl
    • Anna Dołęga
    • Siuzdak Katarzyna
    2020 SURFACE & COATINGS TECHNOLOGY

    Titanium dioxide nanotubes are regarded as one of the most important functional materials and due to their unique electronic properties, chemical stability and photocorrosion resistance, they find applications in, for example, highly efficient photocatalysis or perovskite solar cells. Nevertheless, modification of TiO2 nanotubes is required to overcome their main drawback, i.e. large energy bandgap (>3.2 eV) limiting their ability to capture solar light. In this work, we report the changes in optical and photoelectrochemical properties of well-separated TiO2 nanotubes that are tuned by varying the geometry of the material. The ordered tubular titania is formed via anodization in the presence of fluoride ions in diethylene glycol at elevated temperature. Length, inner diameter, wall thickness, and separation distance are described in function of synthesis parameters such as applied voltage and duration. The morphology and optical properties are characterized by means of scanning electron microscopy and UV–Vis spectroscopy techniques, respectively, while cyclic voltammetry, linear voltammetry and chronoamperometry are used to determine electrochemical/photoelectrochemical activity in different light conditions. The obtained results suggest a link between specific surface area, the width of the band-gap, and photoactivity, each of which could be individually optimised via anodization conditions. Moreover, the behaviour of the Mott-Schottky plot before and after 3 min of irradiation is studied indicating the positive shift of the flat band position and an increase in donor density values for all the obtained materials. The Mott-Schottky analysis was correlated with the linear voltammetry scans suggesting the important role of surface trapped holes. Presented in here results significantly supplement the current state-of-art regarding separated TiO2 nanotubes that are considered as not fully investigated and unappreciated class of titania materials which due to the exposure of inner and outer wall can be used for further modifications.

  • The hydration properties of protein stabilizer, trimethylamine-N-oxide in aqueous solutions of N-methylacetamide – The volumetric and compressibility studies between 288.15 and 308.15 K
    • Emilia Kaczkowska
    • Jarosław Wawer
    • Magdalena Tyczyńska
    • Małgorzata Jóźwiak
    • Agnieszka Boruń
    • Joanna Krakowiak
    2020 Full text THERMOCHIMICA ACTA

    Apparent molar volumes and apparent molar isentropic compressions of the protein stabilizer, trimethylamine-N-oxide (TMAO) were determined from the densities and speed of sound measured at T = (288.15, 298.15 and 308.15) K in aqueous solutions of N-methylacetamide (NMA) at four different concentrations (2, 4, 6 and 8 mol/kg). The concentration dependencies of the calculated quantities extrapolated to the infinite dilution lead to the standard partial molar properties. The latter values were combined with the previously published data for TMAO in pure water, to obtain the partial molar properties of transfer from water to aqueous NMA solutions. From the transfer data the interaction parameters were determined according to the McMillan-Mayer theory formalism. The calculated parameters and their temperature characteristics are discussed in terms of solute-solvent, solute-solute and solute-cosolute interactions and compared with analogous data for protein denaturant, n-butylurea.

  • The Immunogenic and Immunoprotective Activities of Recombinant Chimeric T. gondii Proteins Containing AMA1 Antigen Fragments
    • Justyna Gatkowska
    • Katarzyna Dzitko
    • Bartłomiej Ferra
    • Lucyna Holec-Gąsior
    • Malwina Kawka
    • Bożena Dziadek
    2020 Full text Vaccines

    Toxoplasmosis, one of the most common parasitoses worldwide, is potentially dangerous for individuals with a weakened immune system, but specific immunoprophylaxis intended for humans is still lacking. Thus, efforts have been made to create an efficient universal vaccine for both animals and humans to overcome the shortcomings of currently used treatment methods and protect all hosts against toxoplasmosis. The current work represents a relatively new approach to vaccine development based on recombinant chimeric Toxoplasma gondii antigens. In the present research, three tetravalent chimeric proteins containing different portions of the parasite’s AMA1 antigen: AMA1N-SAG2-GRA1-ROP1L (ANSGR), AMA1C-SAG2-GRA1-ROP1L (ACSGR) and AMA1-SAG2-GRA1-ROP1L (AFSGR) were tested for their immunogenic and immunoprotective capacities. All tested proteins were immunogenic, as evidenced by the triggering of specific humoral and cellular immune responses in vaccinated C3H/HeOuJ mice, defined by the production of specific IgG (IgG1/IgG2a) antibodies in vivo and synthesis of key Th1/Th2 cytokines by Toxoplasma lysate antigen-stimulated splenocytes in vitro. Although all tested preparations provided partial protection against chronic toxoplasmosis in immunized and T. gondii-challenged mice, the intensity of the generated immunoprotection depended on the fragment of the AMA1 antigen incorporated into the chimeric antigen’s structure.

  • The impact of air humidity on the operation of proton exchange membrane fuel cells determined using dynamic electrochemical impedance spectroscopy
    • Ewa Janicka
    • Michał Mielniczek
    • Łukasz Gaweł
    • Kazimierz Darowicki
    • Paulina Landowska
    2020 ELECTROCHIMICA ACTA

    This paper describes the changes in the fuel cell impedance across a range of current loads and humidity changes. The changes of each equivalent circuit parameters representing specific processes occurring in fuel cells, as a function of humidity and current changes, were determined. Within the combined scope of current and humidity, the optimal working conditions of the cells were determined, corresponding to the lowest impedance values. The influence of humidity on the charge transfer resistance behavior and the Warburg coefficient for varying current load values were analyzed in detail.

  • THE IMPACT OF GROUND TIRE RUBBER TREATMENT ON THE THERMAL CONDUCTIVITY OF FLEXIBLE POLYURETHANE/GROUND TIRE RUBBER COMPOSITES
    • Aleksander Hejna
    • Paulina Kosmela
    • Adam Olszewski
    • Łukasz Zedler
    • Krzysztof Formela
    2020 Full text

    Waste car tires are burdensome waste, and their utilization is crucial for the natural environment. In many countries, the primary method of their recycling is energy recovery, performed by simple combustion. However, material recycling is much more effective and significantly more beneficial for the natural environment. It results in the generation of ground tire rubber, which can be used to produce polymerrubber composites. It should be considered as a method of waste rubber utilization. Moreover, it may significantly reduce the use of petroleum-based polymers. Therefore, the environment's total impact could be noticeably reduced, which should be considered a convenient step towards more “green” polymer composites. In the presented paper, the impact of ground tire rubber treatment on the structure and insulation properties of flexible polyurethane/ground tire rubber composite foams was evaluated.

  • The Impact of Lexicon Adaptation on the Emotion Mining From Software Engineering Artifacts
    • Michał Wróbel
    2020 Full text IEEE Access

    Sentiment analysis and emotion mining techniques are increasingly being used in the field of software engineering. However, the experiments conducted so far have not yielded high accuracy results. Researchers indicate a lack of adaptation of the methods of emotion mining to the specific context of the domain as the main cause of this situation. The article describes research aimed at examining whether the adaptation of the lexicon with emotional intensity of words in the context of software engineering improves the reliability of sentiment analysis. For this purpose, a new lexicon is developed in which words are evaluated as if they were used in the field of software engineering. A comparative experiment of emotion mining based on a generic and a software engineering specific lexicon does not reveal any significant differences in the results.

  • The Impact of Material Selection on Durability of Exhaust Valve Faces of a Ship Engine – A Case Study
    • Hanna Smoleńska
    • Włodzimierz Kończewicz
    • Sylwia Bazychowska
    2020 Full text Advances in Science and Technology Research Journal

    wo alloys were used in order to extend the service life of marine engine exhaust valve head. Layers of cobalt base alloys were made of the powders with with chemical composition as follow: the layer marked L12; C-1,55%; Si-1,21%; Cr-29,7%; W-9%; Ni-2%; Mo<0,01%; Fe-1,7%; Co-54,83% and the layer marked N; C-1,45%; Co-38,9%; Cr-24,13%; Ni-10,43%; W-8,75%; Fe-7,64%; Mo-7,56%; Si-2,59%. Base metal was valve steel after heat treatment. It was consisted of: C-0,374%; Cr-9,34%; Mn-0,402%; Ni-0,344%; Si-2,46%; Mo-0,822%; P0,0162%; S-0,001%. Layers on the valve faces were produced by laser cladding using the HPDL ROFIN DL020 laser. Grinding treatment is a very popular form of regeneration of seat and valve plug adhesions. Properly performed grinding operation ensures dimensional and shape accuracy of the surface from 7 to 5 accuracy class and surface roughness Ra not less than 0,16 μm, depending on the object and method of grinding. The 75H and 150S types are a significantly simplified form of valve plug face grinders. Finishing treatment was carried out with a Chris-Marine AB75H sander on a sanding stand equipped with a compressed air system - the stand was designed by the author. The sander has been set up to the surface of the valve stem so that the grinding angle of the valve faces is 30°+10°. A flat grinding wheel T1CRA54–K was used for machining. The plunge feed was g = 0,01 mm/rev. The thickness of the welded layer after grinding was 1,2 mm. Both valves were installed in the ship's engine and were used in real life. After 2000 hours of operation, the valve marked N was damaged. The valve marked L12 showed no damage and was in operation for the next 1000 hours.

  • The Impact of Micro-Sources on Voltage Distortions in a Power Grid
    • Magdalena Grzymkowska
    • Jacek Klucznik
    2020 Full text Acta Energetica

    The increase in the number of photovoltaic (PV) systems integrated with low voltage (LV) grids has led to a great need to analyse the impact of these systems on the quality of electricity and the reliability of its supply. This paper presents and compares the energy quality requirements imposed by various countries on photovoltaic plants. Then, based on real object tests and simulation in DIgSILENT PowerFactory, the impact has been identified of insolation on the generation output, range of harmonic emissions, changes in voltage levels, and total harmonic distortion (THD) in current and voltage. The results depended on the micro-source power and location, and the grid load.

  • The Impact of Spatiotemporal Changes in Land Development (1984–2019) on the Increase in the Runoff Coefficient in Erbil, Kurdistan Region of Iraq
    • Andam Mustafa
    • Michał Szydłowski
    2020 Full text Remote Sensing

    Nowadays, geospatial techniques are a popular approach for estimating urban flash floods by considering spatiotemporal changes in urban development. In this study, we investigated the impact of Land Use/Land Cover (LULC) changes on the hydrological response of the Erbil basin in the Kurdistan Region of Iraq (KRI). In the studied area, the LULC changes were calculated for 1984, 1994, 2004, 2014 and 2019 using the Digital Elevation Model (DEM) and satellite images. The analysis of LULC changes showed that the change between 1984 and 2004 was slower than that between 2004 and 2019. The LULC analysis revealed a 444.4% growth in built-up areas, with a 60.4% decrease in agricultural land between 1984 and 2019. The influence of LULC on urban floods caused by different urbanization scenarios was ascertained using the HEC-GeoHMS and HEC-HMS models. Over 35 years, there was a 15% increase in the peak discharge of outflow, from 392.2 m3/sec in 1984 to 450 m3/sec in 2014, as well as the runoff volume for a precipitation probability distribution of 10%, which increased from 27.4 mm in 1984 to 30.9 mm in 2014. Overall, the probability of flash floods increased in the center of the city due to the large expansion of built-up areas.

  • The impact of the AC922 Architecture on Performance of Deep Neural Network Training
    • Paweł Rościszewski
    • Michał Iwański
    • Paweł Czarnul
    2020

    Practical deep learning applications require more and more computing power. New computing architectures emerge, specifically designed for the artificial intelligence applications, including the IBM Power System AC922. In this paper we confront an AC922 (8335-GTG) server equipped with 4 NVIDIA Volta V100 GPUs with selected deep neural network training applications, including four convolutional and one recurrent model. We report performance results depending on batch sizes and GPU selection and compare them with the results from another contemporary workstation based on the same set of GPUs – NVIDIA® DGX Station ™ . The results show that the AC922 performs better in all tested configurations, achieving improvements up to 10.3%. Profiling indicates that the improvement is due to the efficient I/O pipeline. The performance differences depend on the specific model, rather than on the model class (RNN/CNN). Both systems offer good scalability up to 4 GPUs. In certain cases there is a significant difference in performance depending on exactly which GPUs are used for computations.

  • The Impact Of The Selected Parameters Of Fdm Manufacturing Technology On Tribological Performance Of Abs–Steel Pair Under Dry Friction
    • Katarzyna Suwińska
    • Jacek Łubiński
    2020 Full text TRIBOLOGIA

    The paper presents the result of tribological test of ABS and steel samples sliding under dry friction. Polymeric samples were manufactured of ABS material using FDM technology. Testing was carried out in unidirectional sliding in a ring-on-flat contact in a PT-3 tribometer. The scope of tested parameters included volumetric and mass wear, the friction coefficient, and polymeric specimen temperature. Polymeric specimens used in the study were manufactured at various settings of the 3D printing process such as the orientation of the specimen in print with respect to the printer building tray and the thickness of a single layer of the deposited material. Comparisons of the impact of these parameters on tribological performance of the sliding contact were analysed.

  • The impedance of hydrogen oxidation reaction in a proton exchange membrane fuel cell in the presence of carbon monoxide in hydrogen stream
    • Kazimierz Darowicki
    • Łukasz Gaweł
    • Michał Mielniczek
    • Artur Zieliński
    • Ewa Janicka
    • Jurgen Hunger
    • L. Jorissen
    2020 Full text APPLIED ENERGY

    Evaluation of performance of a proton exchange membrane fuel cell, which is affected by carbon monoxide that pollutes the hydrogen stream, was presented. This influence was studied for carbon monoxide concentration of 125–325 ppb, which are close to values specified in ISO 14687:2019 standard. Performed studies provided crucial information for further development of fuel cell as an energy source for automotive application. Impedance with the use of Dynamic Electrochemical Impedance Spectroscopy profile measurements were completed for chosen carbon monoxide concentration under a constant current load and anode impedance variations were determined as a function of the time exposed to carbon monoxide. A method to determine the impedance of hydrogen oxidation was proposed. It was determined how the carbon monoxide surface coverage of anodic catalyst varies as a function of time. The capacitance of the double electrical layer and the charge transfer resistance of anodic reaction are discussed to evaluate them with respect to exposure time and surface coverage. It has been shown that proposed methodology can be used as a universal tool for testing fuel cells for both research and industrial applications, with the overall aim of optimization, monitoring, and diagnostics of the fuel cell.