Repozytorium publikacji - Politechnika Gdańska

Ustawienia strony

english
Repozytorium publikacji
Politechniki Gdańskiej

Pokaż publikacje z roku

Ostatnie pozycje

  • Structural and catalytic properties of ceria layers doped with transition metals for SOFCs fueled by biogas
    • Bartosz Hołówko
    • Patryk Błaszczak
    • Mikołaj Chlipała
    • Maria Gazda
    • Sea-Fue Wang
    • Piotr Jasiński
    • Beata Bochentyn
    2020 Pełny tekst INTERNATIONAL JOURNAL OF HYDROGEN ENERGY

    The aim of this paper was to investigate an influence of the nanocrystalline Ce0.8A0.2O2-δ (A = Mn, Fe, Co, Ni, Cu) materials on the direct internal reforming of biogas in SOFC. Structural analysis of fabricated compounds has been done. An in-situ analysis of a composition of outlet gases from operating SOFC was performed using FTIR spectroscopy with simultaneous electrical tests. It was found out, that type of dopant strongly affects biogas reforming process. The differences in absolute values of current density resulted mostly from a microstructure and probably phase composition of a deposited layers. Fuel cells with Ce0.8Co0.2O2-δ and Ce0.8Ni0.2O2-δ additional layers presented the highest drop of current density after switching from hydrogen to biogas, but simultaneously they were the most stable in time. Additional chemical analysis revealed that steam reforming and methane pyrolysis might be dominating reactions while working in biogas atmosphere.

  • Structural and Temporal Topic Models of Feedbacks on Service Quality – A Path to Theory Development?
    • Ojo Adegboyega
    • Nina Rizun
    2020

    There is growing interest in applying computational methods in analysing large amount of data without sacrificing rigour in Information Systems research. In this paper, we demonstrate how the use of structural and temporal topic modelling can be employed to produce insights of both theoretical and practical importance from the analysis of textual comments on the quality of services in hospitals. As a first step, we revealed the thematic structures in the comments as topics which were aligned with the SERVQUAL dimensions. Following this, we established the temporal precedence among SERVQUAL factors based on the evolution of the topics over time. Theoretically, our findings are consistent with the emerging consensus on the nature of SERVQUAL dimensions from extant quantitative research and offer new propositions on the relationships among these dimensions. From the practice perspective, we produced quantified measures of factors associated with healthcare service experience

  • Structural Assessment of Reinforced Concrete Beams Incorporating Waste Plastic Straws
    • Jamal M. Khatib
    • Ali Jahami
    • Adel Elkordi
    • Hakim Abdelgader
    • Mahammed Sanebi
    2020 Pełny tekst Environments

    The behavior of reinforced concrete beams containing fibers made of waste plastic straws (WPSs) under the three point bending test is examined. The effect of WPS fiber addition on the compressive and split tensile strength is reported. Four concrete mixes were prepared. The control mix PS-0 had a proportion of 1 cement: 1 sand: 2 coarse aggregate and a water cement ratio of 0.4. In the other three mixes PS-0.5, PS-1.5 and PS-3, 0%, 0.5%, 1.5% and 3% of WPS fiber (by volume) was added respectively. The results show that at 0.5% WPS, there is slight increase in compressive strength. However, beyond 0.5% addition, a decrease in compressive strength is observed. The split tensile strength shows a systematic increase with the addition of WPS fibers. The reinforced concrete beams containing WPS fibers show higher ductility as demonstrated by the larger ultimate tensile strain and ductility index (Δu/Δy). There is a tendency to have more fine cracks with the presence of WPS fibers.

  • Structural Insights into New Bi(III) Coordination Polymers with Pyridine-2,3-Dicarboxylic Acid: Photoluminescence Properties and Anti-Helicobacter pylori Activity
    • Mateusz Kowalik
    • Joanna Masternak
    • Iwona Łakomska
    • Katarzyna Kazimierczuk
    • Anna Zawilak-Pawlik
    • Piotr Szczepanowski
    • Oleksiy Khavryuchenko
    • Barbara Barszcz
    2020 Pełny tekst INTERNATIONAL JOURNAL OF MOLECULAR SCIENCES

    Two novel coordination polymers, [Bi2(2,3pydc)2(2,3pydcH)2(H2O)]n(1) and {(Et3NH)2[Bi(2,3pydc)(2,3pydcH)Cl2]}n(2) were prepared using as a prolinker pyridine-2,3-dicarboxylic acid(2,3pydcH2). The obtained complexes were fully characterized by elemental analysis, TG/DTG, FT-IR,solid-state photoluminescence, DFT calculations and single-crystal X-ray diffraction. The obtainedcomplexes crystallized in the triclinicP-1 space group (1) and comprise dimeric units with twocrystallographically different Bi(III) centers (polyhedra: distorted pentagonal bipyramid andbicapped trigonal prism) and monoclinicP21/cspace group (2) with a distorted monocappedpentagonal bipyramid of Bi(III) center. The various coordination modes of bridging carboxylateligands are responsible for the formation of 1D chains with4,5C10(1) and2C1(2) topology.The photoluminescence quantum yield for polymer2is 8.36%, which makes it a good candidate formore specific studies towards Bi-based fluorescent materials. Moreover, it was detected that polymer1is more than twice as active againstH. pylorias polymer2. It can be concluded that there is anexisting relationship between the structure and the antibacterial activity because the presence ofchloride and triethylammonium ions in the structure of complex2reduces the antibacterial activity.

  • Structural, magnetic and spectral properties of tetrahedral cobalt(II) silanethiolates: a variety of structures and manifestation of field-induced slow magnetic relaxation
    • Daria Kowalkowska-Zedler
    • Anna Dołęga
    • Natalia Nedelko
    • Renata Łyszczek
    • Pavlo Aleshkevych
    • Iraida Demchenko
    • Justyna Łuczak
    • Anna Ślawska-waniewska
    • Agnieszka Pladzyk
    2020 DALTON TRANSACTIONS

    Blue crystals of five heteroleptic cobalt(II) silanethiolates 1–5 have been obtained by the reaction of [Co{SSi (tBuO)3}2(NH3)]2 with aminopyridines and aminomethylpyridines at an appropriate molar ratio and their structural, spectral, thermal and magnetic properties have been established and described. All complexes 1–5 contain Co(II) ions in a tetrahedral CoN2S2 environment formed by (tBuO)3SiS− residues and pyridines and present variable structures. Complexes 1–3 are mononuclear [Co{SSi(tBuO)3}2(L1)2] (L1 = 2-aminopyridine 2AP, 3-aminopyridine 3AP, and 4-aminopyridine 4AP). The application of 3AMP and 4AMP (3-aminomethylpyridine and 4-aminomethylpyridine) allows either dinuclear complex 4 [Co{SSi(tBuO)3}2(μ-3AMP)]2 or 1D coordination polymer 5 with the formula of [Co{SSi(tBuO)3}2(μ-4AMP)]n to be obtained. The molecular structures of 1–5 were determined by single-crystal X-ray and powder diffraction, UV-vis and FTIR spectrocopy for solid samples and their thermal properties were characterized by TG-DSC and TG-FTIR methods. The dc and ac magnetic and EPR studies of polycrystalline samples have been performed. For all complexes, the obtained data show a behavior typical of paramagnetic high–spin Co(II) ions in a tetrahedral geometry, with a considerable contribution of the ZFS effect in a low temperature range. All complexes were also probed for SIM behavior. The modeling of the magnetic and EPR data was done for samples 1, 3, 4 and 5 to estimate ZFS parameters. The obtained results imply a negative value of the axial parameter D in complex 4 and positive D values for the rest of the compounds. A comparative magneto-structural analysis of complexes 4 and 5 points to the high sensitivity of the single-ion magnetic anisotropy of tetrahedral Co (II) complexes to subtle changes in the first and second coordination spheres of Co(II) ions.

  • Structural Properties and Water Uptake of SrTi1−xFexO3−x/2−δ
    • Tadeusz Miruszewski
    • Kacper Dzierzgowski
    • Piotr Winiarz
    • Sebastian Wachowski
    • Aleksandra Mielewczyk-Gryń
    • Maria Gazda
    2020 Pełny tekst Materials

    In this work, Fe-doped strontium titanate SrTi1−xFexO3−x/2−δ, for x = 0–1 (STFx), has been fabricated and studied. The structure and microstructure analysis showed that the Fe amount in SrTi1−xFexO3−x/2−δ has a great influence on the lattice parameter and microstructure, including the porosity and grain size. Oxygen nonstoichiometry studies performed by thermogravimetry at different atmospheres showed that the Fe-rich compositions (x > 0.3) exhibit higher oxygen vacancies concentration of the order of magnitude 1022–1023 cm−3. The proton uptake investigations have been done using thermogravimetry in wet conditions, and the results showed that the compositions with x < 0.5 exhibit hydrogenation redox reactions. Proton concentration at 400 °C depends on the Fe content and was estimated to be 1.0 × 10−2 mol/mol for SrTi0.9Fe0.1O2.95 and 1.8 × 10−5 mol/mol for SrTi0.5Fe0.5O2.75. Above 20 mol% of iron content, a significant drop of proton molar concentrations at 400 °C was observed. This is related to the stronger overlapping of Fe and O orbitals after reaching the percolation level of approximately 30 mol% of the iron in SrTi1−xFexO3−x/2−δ. The relation between the proton concentration and Fe dopant content has been discussed in relation to the B-site average electronegativity, oxygen nonstoichiometry, and electronic structure.

  • Structure and water uptake in BaLnCo2O6−δ (Ln =La, Pr, Nd, Sm, Gd, Tb and Dy)
    • Sebastian Wachowski
    • Iga Szpunar
    • Magnus H. Sorby
    • Aleksandra Mielewczyk-Gryń
    • Maria Balaguer
    • Corneliu Ghica
    • Marian Cosmin Istrate
    • Maria Gazda
    • Anette E. Gunnæs
    • José M Serra
    • Truls Norby
    • Ragnar Strandbakke
    2020 Pełny tekst ACTA MATERIALIA

    The structure of BaLnCo2O6-δ (Ln =La, Pr, Nd, Sm, Gd, Tb and Dy) was studied by the means of synchrotron radiation powder X-ray diffraction, neutron powder diffraction and Transmission Electron Microscopy (TEM), while water uptake properties were analysed with the use of thermogravimetry (TG) and water adsorption isotherms. The structure refinement revealed that the dominant phase in all compositions was orthorhombic with an ordering of the A-site cations along the c-axis and ordering of oxygen vacancies along the b-axis, which was also directly evidenced by TEM. It was shown that both unit cell volume and average Co-oxidation state at room temperature decrease linearly with decreasing Ln radius. TG water uptake experiments in humidified N2–O2 gas mixture at 300 °C revealed that among all compositions, only BaLaCo2O6-δ and BaGdCo2O6-δ exhibit significant water uptake. Surface water adsorption studies showed that the α, a normalised parameter reflecting the surface hydrophilicity, mostly independently of Ln radius was close to 0.5, which means that the surface is neither hydrophobic nor hydrophilic. The results indicated that water uptake observed at 300 °C is a bulk process, which cannot be described by standard hydration/hydrogenation reaction and it is related to the layered structure of the perovskite lattice and characteristic to La or Gd being present in the lattice.

  • Structure of the interlayer between Au thin film and Si-substrate: Molecular Dynamics simulations
    • Valeriy Plechystyy
    • Ihor Shtablavyi
    • Szymon Winczewski
    • Kamil Rybacki
    • Stepan Mudry
    • Jarosław Rybicki
    2020 Pełny tekst Materials Research Express

    Interaction between 2, 3, 5 and 7 atomic layers of gold and a (111) silicon surface was investigated with the molecular dynamics simulation method. The simulation of the diffusion interaction between gold and silicon in the temperature range 425-925 K has been carried out. The peculiarities of the concentration changes of the interacting components and the atomic density at the boundary of two phases in the direction perpendicular to the crystalline surface were established. By means the formalism of quasi two dimensional partial pair correlation functions the atomic structure of the diffusion region was analyzed. The formation of the alloy of eutectic composition within the gold-silicon interlayer was established. It was shown that the inter-phase mixing in various temperature intervals occurred according to different diffusion mechanisms

  • Students’ soft urban planning skills and local development are the benefits from the Fair of Good Practice. Small cities - big challengesprogramme
    • Karolina Krośnicka
    2020 Pełny tekst World Transactions on Engineering and Technology Education

    The urban planner in practice needs soft skills when dealing with public consultations connected to local development plans. To improve the abilities of architecture and urban planning students to discuss solutions and to support the development of local public spaces of small towns in the Pomeranian voivodeship ( province) in Poland, the Fair of Good Practice. Small cities - big challenges programme was developed. It was organised as a series of four projects, each in the form of an urban design studio, and was implemented in the Faculty of Architecture at Gdańsk University of Technology (FA-GUT), between 2016 and 2018. The programme covered urban design topics in two towns of the Pomeranian voivodeship (Rumia and Reda). It was an example of involvement in teaching of different stakeholders connected with urban planning, with an intergenerational exchange of knowledge and support for public participation.

  • STUDY OF CuO AND V2O5 EFFECT ON IR SPECTRA OF POLYCRYSTALLINE BISMUTH NIOBATE
    • Iwona Kuźniarska-Biernacka
    • Agata Lisińska-Czekaj
    • Dionizy Czekaj
    2020 Pełny tekst ARCHIVES OF METALLURGY AND MATERIALS

    Bismuth niobate (BiNbO4) ceramics were fabricated by mixed oxide method and sintered by presureless sintering method. BiNbO4 ceramics doped with V2O5 additive in amount 0.125 wt%, 0.250 wt% and 1 wt% of was sintered at T = 910°C whereas BiNbO4 ceramics doped with 2 wt% of CuO additive was sintered at T = 890°C and T = 910°C. It was found that V2O5 additive improved morphology of the ceramic samples. However, the chemical composition of BiNbO4 ceramics in relation to bismuth oxide and niobium oxide manifested a tendency of lack of Bi2O3 component. Absorption bands for the BiNbO4 compound were identified. FTIR band positions associated with NbO6 octahedra suggested that the crystal structure changes after V2O5 incorporation.

  • Study of oxygen electrode reactions on symmetrical porous SrTi0.30Fe0.70O3-δ electrodes on Ce0.8Gd0.2O1.9 electrolyte at 800 °C–500 °C
    • Aleksander Mroziński
    • Sebastian Molin
    • Piotr Jasiński
    2020 Pełny tekst ELECTROCHIMICA ACTA

    Iron doped strontium titanates (SrTi1-xFexO3-δ) are an interesting mixed ionic-electronic conductor model used to study basic oxygen reduction/oxidation reactions. In this work, we performed an impedance spectroscopy study on symmetrical porous SrTi0.30Fe0.70O3-δ (STF70) electrodes on a ceriabased electrolyte. The sample was measured in varying oxygen concentration: from 0.3% to 100% in 800 °C - 500 °C temperature range. Low polarisation resistance (e.g. <125 mΩ cm2 at 600 °C in the air) values were obtained, showing an overall high performance of the STF70 electrode. Impedance data analysis was assisted by the distribution of relaxation times method, which allowed an equivalent electrical circuit to be proposed comprising of two resistance/constant phase element sub-circuits connected in series. The medium frequency contribution, with a characteristic frequency of ~2000 Hz at 800 °C in air, originates most probably from possible surface diffusion followed by charge transfer reaction limitation, whereas the lower frequency contribution (characteristic frequency <10 Hz) is due to gas-phase diffusion.

  • Study of railway traffic safety based on the railway track condition monitoring system
    • S Kliuiev
    • Ievgen Medvediev
    • N Khalipova
    2020

    The solution to the problem of monitoring the railway track, as well as potentially dangerous objects and phenomena in the adjacent territories, is determined by the need to implement increased requirements for traffic safety (primarily to the geometric parameters of the devices of a long railway track under construction and functioning load-bearing highways), prevention of technological disasters and large-scale negative effects of natural phenomena on the railways. The continuous process of integrating methods and means of monitoring and preventing emergencies into a single information management system is shown. The possibility of determining a dynamic model of the adverse effect of the train on the track and the most unfavorable for the track train and traction parameters, which must be avoided when forming trains in this section, is established. Three key factors are formulated, the use of which will reduce the negative impact on the track from trains. The concept of information technology improvement of the monitoring system for potentially dangerous sections of the railway on the basis of new innovative technologies has been developed.

  • Study of the Effect of Filling Thermoplastic Medical Polyurethane with PVA, PLA or Diatomite on the Relaxation Times Distributions of 1H NMR
    • Justyna Kucińska-Lipka
    • Nikolay Sinyavsky
    • I. Mershiev I.
    • Józef Haponiuk
    2020 Pełny tekst APPLIED MAGNETIC RESONANCE

    In this work, to characterize the mobility of diferent sections of the macromole‑ cules of polyurethane (PUR), polyvinyl alcohol (PVA), and polylactic acid (PLA), as well as the density of crosslinks of the polymer chains when using fllers, we used the distributions of spin–lattice and spin–spin relaxation times for the protons. It is shown that the rigidity of the thermoplastic polymers depends on the sizes of the granules of the diatomite fller, which can embed in the polymer matrix. Conse‑ quently, relaxation times are reduced. If PLA is the fller of PUR, the dynamics of the molecules in the chains and the spin–spin interaction of the protons are afected by the crosslinking of PUR by PLA. An increase in crosslinks density reduces the rate of polymer degradation.

  • Study on applicability of two modal identification techniques in irrelevant cases
    • Agnieszka Tomaszewska
    • Marek Szafrański
    2020 Pełny tekst Archives of Civil and Mechanical Engineering

    Study on applicability of two modal identification techniques in irrelevant cases is made in this paper. The following techniques are considered: Peak Picking based on correlation analysis (PP-CA), dedicated for ambient vibrations and Eigensystem Realization Algorithm (ERA), formulated for free decay vibrations investigation. Irrelevant cases are found when analyzed signals are different than recommended to a given technique. The study is conducted on examples of two real structures: masonry tower and steel railway bridge. Both cases are diverse in age, material, excitation and vibrations energy. The signals measured on the tower are suitable for the PP-CA technique (ambient vibrations), while the signals measured on the bridge are suitable for the ERA (free decay vibrations). However, both methods have been applied to both systems. Natural frequencies, mode shapes and damping ratios are identified and the effectiveness of the irrelevant technique is assessed in relation to the results obtained by the relevant method in each case.

  • Study on Methods to Control Interstory Deflections
    • Seyed Mohammad Khatami
    • Hosein Naderpour
    • Seyed Mohammad Nazem Razavi
    • Rui Barros
    • Anna Jakubczyk-Gałczyńska
    • Robert Jankowski
    2020 Pełny tekst Geosciences

    One of the possibilities to prevent building pounding between two adjacent structures is to consider appropriate in-between separation distance. Another approach might be focused on controlling the relative displacements during seismic excitations. Although the majority of building codes around the world recommend the use of some equations of various distances between structures to avoid pounding; a lot of reports after earthquakes have obviously shown that safety situation or economic consideration is not always provided due to the collisions between buildings and high cost of land; respectively. The aim of the present paper is to focus the analysis on the properties of structures and conduct an in-depth analysis of available methods to control interstory deflections so as to prevent pounding. For this purpose, a numerical lumped mass model of the five-story building has been considered and its response under different earthquake records has been investigated. Firstly, the influence of the change in structural properties (story stiffness; mass and damping) has been examined. Then the application of tuned mass damper, base isolation and base isolation with rubber bumpers has been considered. The results of comparative analyses clearly indicate that using base isolation, with the addition of bumpers, can be selected as the best method to control building deflections and decrease absolute lateral displacement between two buildings so as to prevent their pounding during earthquakes.

  • Study on Polymer Elements for Mitigation of Earthquake-Induced Pounding Between Buildings in Complex Arrangements
    • Barbara Sołtysik
    • Tomasz Falborski
    • Robert Jankowski
    2020

    Pounding between neighboring structures during seismic events has been revealed as one of the most commonly observed reasons for severe damage or even total collapse of the adjacent buildings. Therefore, pounding effects have recently become an issue of great interest of many numerical and experimental investigations in many earthquake-prone regions of the world. It has also been observed that the differences in dynamic characteristics is the key reason leading to interaction between colliding, insufficiently separated structures. The problem is much more complicated for complex arrangements of structures, for example, in the case of collisions between few structures in a row. A lot of different approaches have been considered to mitigate earthquake-induced structural pounding. One method is based on placing between the structures some viscoelastic elements acting as bumpers. Another one is stiff linking the structures. It allows the forces to be transmitted between buildings and thus eliminate undesired interactions. The aim of this paper is to present the results of experimental research focused on mitigation of pounding between buildings in complex arrangements by using polymer elements installed between structures. In the present study, three steel models characterized by various dynamic properties and different in-between distances were investigated. Additional masses were mounted at the top of each model in order to obtain different dynamic characteristics. The unidirectional shaking table, available at the Gdansk University of Technology (Poland), was employed to conduct this study. Experimental models were mounted to shaking table platform. The results of the study explicitly show that the approach of using polymer elements can be an effective pounding mitigation technique in the case of complex arrangement of buildings. It may partially or fully prevent from damaging collisions between adjacent buildings during seismic events. It also enhances the dynamic response leading to the reduction in lateral vibrations under different strong ground excitations.

  • Study on the Coastline Evolution in Sopot (2008–2018) Based on Landsat Satellite Imagery
    • Mariusz Specht
    • Cezary Specht
    • Oktawia Lewicka
    • Artur Makar
    • Paweł Burdziakowski
    • Paweł Dąbrowski
    2020 Pełny tekst Journal of Marine Science and Engineering

    The coastline is the boundary between the water surface in a reservoir or watercourse and the land, which is characterised by high instability and functional diversity. For these reasons, research on coastal monitoring has been conducted for several decades. Currently, satellite images performed with synthetic aperture radars (SARs) are used to determine its course and variability together with high-resolution multispectral imagery from satellites such as IKONOS, QuickBird, and WorldView, or moderate-resolution multispectral images from Landsat satellites. This paper analysed the coastline variability in Sopot (2008–2018) based on Landsat satellite imagery. Furthermore, based on multispectral images obtained, it was determined how the beach surface in Sopot changed. Research has shown that the coastline keeps moving away from the land every year. This was particularly noticeable between 2008 and 2018 when the coastline moved on average 19.1 m towards the Baltic Sea. Moreover, it was observed that the area of the sandy beach in Sopot increased by 14 170.6 m2, which translates into an increase of 24.7% compared to 2008. The probable cause of the continuous coastline shift towards the sea and the increase of the beach surface is the oceanographic phenomenon called tombolo, which occurred in this area as a result of the construction of a yacht marina near the coast.

  • Study on the Structure-Property Dependences of Rigid PUR-PIR Foams Obtained from Marine Biomass-Based Biopolyol
    • Paulina Kosmela
    • Aleksander Hejna
    • Jan Suchorzewski
    • Łukasz Piszczyk
    • Józef Haponiuk
    2020 Pełny tekst Materials

    The paper describes the preparation and characterization of rigid polyurethane-polyisocyanurate (PUR-PIR) foams obtained with biopolyol synthesized in the process of liquefaction of biomass from the Baltic Sea. The obtained foams differed in the content of biopolyol in polyol mixture (0–30 wt%) and the isocyanate index (IISO = 200, 250, and 300). The prepared foams were characterized in terms of processing parameters (processing times, synthesis temperature), physical (sol fraction content, apparent density) and chemical structure (Fourier transform infrared spectroscopy), microstructure (computer microtomography), as well as mechanical (compressive strength, dynamic mechanical analysis), and thermal properties (thermogravimetric analysis, thermal conductivity coefficient). The influence of biopolyol and IISO content on the above properties was determined. The addition of up to 30 wt% of biopolyol increased the reactivity of the polyol mixture, and the obtained foams showed enhanced mechanical, thermal, and insulating properties compared to foams prepared solely with petrochemical polyol. The addition of up to 30 wt% of biopolyol did not significantly affect the chemical structure and average cell size. With the increase in IISO, a slight decrease in processing times and mechanical properties was observed. As expected, foams with higher IISO exhibited a higher relative concentration of polyisocyanurate groups in their chemical structure, which was confirmed using principal component analysis (PCA).

  • Studying the Effect of Working Conditions on WEDM Machining Performance of Super Alloy Inconel 617
    • Stefan Dzionk
    • Mieczysław Siemiątkowski
    2020 Pełny tekst Machines

    Wire electrical discharge machining (WEDM) has been for many years a precise and efficient non-conventional manufacturing solution in various industrial applications, mostly involving the use of hard-to machine materials like, among other, the Inconel super alloys. The focus of the present study is on exploring the effect of selected control parameters, including pulse duration, pulse-off time and the dielectric flow pressure on the WEDM process performance characteristics of Inconel 617 material such, as: volumetric material removal rate (MRR), the dimensional accuracy of cutting (reflected by the kerf width) and surface roughness (SR). The research experiment has been designed and carried out using the response surface methodology (RSM) accordingly with the Box-Behnken design scheme. The results of experiments derived in the form of a fitted regression model have been subjected to the analysis of variance (Anova) tests. Thus, the variable process parameters and the relevant interactions between them characterized by a significant influence on the values of the derived output responses could be explicitly determined.

  • Subcritical Thermodynamic Cycles with Organic Medium and Isothermal Expansion
    • Krzysztof Kosowski
    • Marian Piwowarski
    2020 Pełny tekst ENERGIES

    The efffciencies of the Organic Rankine Cycle (ORC) are not very high and only very seldom do they exceed 20%. The increase and optimization of initial parameters and certain modifications of the thermodynamic cycle make it possible to overcome these drawbacks. A new modified cycle has been described and analyzed in detail in the paper. Similarly to the Ericsson cycle for gas turbines, isothermal expansion in the turbine is suggested for the power plant with organic media. The new cycle and the typical ORC power plants have the same block diagram. The only difference is that expansion in the proposed cycle occurs not adiabatically but as an isothermal process. The thermodynamic calculations have been carried out for 11 various fluids and 4 different cycles. The obtained results have clearly shown that cycles with isothermal expansion (isothermal turbines) are characterized by remarkably higher efffciency than typical power plants with adiabatic turbines. The increase in efffciency varies from 6 to 12 percent points for cycles with saturated live vapor and from 4 to 7 percent points for cycles with superheated live vapor. The performed analyses have shown that it is possible to achieve a very high efffciency (over 45%) of organic cycle, which is a very competitive value. In such cases the proposed power plants can achieve an efficiency which is higher than that of modern steam turbine plants with supercritical parameters.

  • SUBIEKTYWNA OCENA MULTIPLEKSU RADIOFONII LOKALNEJ DAB+ DZIAŁAJĄCEJ W GDAŃSKU I WROCŁAWIU
    • Przemysław Falkowski-Gilski
    • Stefan Brachmański
    • Andrzej Dobrucki
    2020 Przegląd Telekomunikacyjny + Wiadomości Telekomunikacyjne

    Standard DAB+ (Digital Audio Broadcasting plus) jest wiodącym systemem naziemnej radiofonii cyfrowej. W porównaniu do analogowej radiofonii FM wszystkie usługi, obejmujące tradycyjne programy radiowe oraz usługi transmisji danych, grupowane są w zbiór (ensemble). Praca ta przedstawia proces rekonfiguracji polskiego multipleksu na przykładzie lokalnej radiofonii DAB+ w Gdańsku i Wrocławiu. Opisuje wyniki badań subiektywnych dotyczących jakości programów radiowych nadawanych jednocześnie w technice cyfrowej i analogowej.

  • Subjective and Objective Quality Evaluation Study of BPL -PLC Wired Medium
    • Grzegorz Debita
    • Przemysław Falkowski-Gilski
    • Marcin Habrych
    • Bogdan Miedziński
    • Bartosz Polnik
    • Jan Wandzio
    • Przemysław Jedlikowski
    2020 Pełny tekst Elektronika Ir Elektrotechnika

    This paper presents results of research on the effectiveness of bi-directional voice transmission in a 6 kV mine cable network using BPL-PLC (Broadband over Power Line - Power Line Communication) technology. It concerns both emergency cable state (supply outage with cable shorted at both ends) and loaded with distorted current waveforms. The narrowband (0.5 MHz–15 MHz) and broadband (two different modes, frequency range of 3 MHz–7.5 MHz) transmission efficiency, considered as an objective study, was correlated with the level of noise in the cable for both induction-inductive and mixed capacitive-inductive coupling of the measurement devices and/or modems. The quality of voice transmission, considered as a subjective study, was assessed by a group of 15 people aged between 25 and 35 years old. The test audio signals included samples in 3 languages sourced from ITU (International Telecommunication Union) and processed in 3 bitrates ranging from 8 kbps to 24 kbps.

  • Subjective Quality Evaluation of Speech Signals Transmitted via BPL-PLC Wired System
    • Przemysław Falkowski-Gilski
    • Grzegorz Debita
    • Marcin Habrych
    • Bogdan Miedziński
    • Przemysław Jedlikowski
    • Bartosz Polnik
    • Jan Wandzio
    • Xin Wang
    2020

    The broadband over power line – power line communication (BPL-PLC) cable is resistant to electricity stoppage and partial damage of phase conductors. It maintains continuity of transmission in case of an emergency. These features make it an ideal solution for delivering data, e.g. in an underground mine environment, especially clear and easily understandable voice messages. This paper describes a subjective quality evaluation of such a system. The solution was designed and tested in real-time operating conditions. It consists of a one-way transmission system, dedicated to delivering speech signals and voice commands. The study involved signal samples in three languages: English, German, and Polish, processed at different bitrates: 8, 16, and 24 kbps. Obtained results confirmed the usefulness of BPL-PLC technology for speech transmission purposes. Even in a narrowband scenario, with bitrates smaller than 1 Mbps, it proved to be a potentially life-saving communication system. Results of this study may aid researchers and parties from the mining and oil industry, as well as professionals involved in rescue operations.

  • Subjective Quality Evaluation of Underground BPL-PLC Voice Communication System
    • Grzegorz Debita
    • Przemysław Falkowski-Gilski
    • Marcin Habrych
    • Bogdan Miedziński
    • Bartosz Polnik
    • Jan Wandzio
    • Przemysław Jedlikowski
    2020

    Designing a reliable voice transmission system is not a trivial task. Wired media, thanks to their resistance to mechanical damage, seem an ideal solution. The BPL-PLC (Broadband over Power Line – Power Line Communication) cable is resilient to electricity stoppage and partial damage of phase conductors. It maintains continuity of transmission in case of an emergency situation, including paramedic rescue operations. These features make it an ideal solution for delivering data, e.g. in an underground mine environment. This paper describes a subjective quality evaluation of such a system. The solution was designed and tested in real-time operating conditions. It involved two types of coupling, namely: induction-inductive and capacitive-inductive, as well as two transmission modes (Mode 1 and Mode 11 operating in the 2–7.5 MHz frequency range). The tested one-way transmission system was designed to deliver clear and easily understandable voice messages. The study involved signal samples in three languages: English (both British and American dialects), German, and Polish, processed in three bitrates: 8, 16, and 24 kbit/s, with the Ogg Vorbis codec. Obtained results confirmed the usefulness of the BPL-PLC technology for voice communication purposes. Results of this study may be of interest to professionals from the mining and oil industry.

  • Submicron inorganic particles as an additional filler in hybrid epoxy matrix composites reinforced with glass fibres
    • Marcin Włoch
    • Filip Bagiński
    • Piotr Koziński
    • Janusz Datta
    2020 POLYMERS & POLYMER COMPOSITES

    In this study, the effect of selected submicron metal oxide (zinc oxide, titanium oxide) or non-metal oxide (silicon dioxide) particles on mechanical and thermo-mechanical properties of epoxy/glass composites was investigated. The applied epoxy resin was a diglycidyl ether of bisphenol-A cured with triethylenetetramine. As a reinforcement twill weave E-glass fabric was used. Hybrid composites (contained particulate and fibrous filler) were fabricated by using the hand lay-up method and the average content of glass fibres was 39–41 wt%. Flexural properties, thermo-mechanical properties, abrasion resistance and hardness were determined for each group of the prepared hybrid epoxy/glass composites. The obtained results were compared with control samples (without submicron particles). Investigations showed that the addition of 2 wt% SiO2, 4 wt% TiO2 or 4 wt% ZnO to epoxy resin improved the flexural strength and the flexural modulus of composites. Dynamic mechanical analysis showed that the addition of the mentioned particles enhanced storage and loss modulus. It can be attributed to the good dispersion and good interaction between submicron-mentioned particles and the epoxy matrix.

  • Sub-national structures matter when evaluating physical activity promotion: Lessons from Germany
    • Sarah Forberger
    • Peter Gelius
    • Sven Messing
    • Kevin Volf
    • Liam Kelly
    • Simon J. E. Taylor
    • Joanna Żukowska
    • Jeroen Lakerveld
    • Catherine Woods
    2020 EUROPEAN JOURNAL OF PUBLIC HEALTH

    Background Public policies are increasingly acknowledged as important part of promoting physical activity (PA). However, especially in states with sub-national administrative structures such as Germany, national and sub-national approaches differ considerably. In Germany, sport for all (SfA) promotion is mostly organized at sub-national level, which is usually not covered in national evaluations. Knowledge of these structures helps to understand national outcomes, enables comparisons and learning within and between countries, and assists in identifying support structures for effective PA promotion. Methods Data were collected in the PEN Policy Evaluation Network project. In addition to the WHO HEPA PAT, a questionnaire was sent to the sports representatives of the 16 federal states. Responses of 11 state representatives were included and overarching issues were identified using inductive thematic analysis. Results PA promotion in Germany is organized in three areas: SfA, professional sports and school sports. SfA promotion at sub-national level is assigned to different administrative bodies (ministries, senate administration, state chancellery) and policy areas: culture, health and care, home affairs with various aspects, education, social affairs and family. The priorities of the federal states are more diverse and specific compared to the national level. There is an overlap in the topics: urban planning, cycling, health prevention and targeting children. Cooperation mechanisms and partners vary between federal states, but some partners are active at sub-national and national level. Conclusions The results provide an insight into the complexity of PA and especially SfA promotion at sub-national level in Germany. Our results suggest that a broader range of approaches is used in the 16 German states than national overviews would suggest. These particularities must be taken into account when assessing and comparing the results from different countries.

  • Substancje biogenne i inne problemy w zarządzaniu wodami opadowymi w portach
    • Klaudia Kosek
    • Małgorzata Szopińska
    • Hubert Byliński
    • Wojciech Artichowicz
    • Sylwia Fudala-Książek
    • Aneta Łuczkiewicz
    2020 Pełny tekst Pismo PG

    Do niedawna uważano, że substancjami zanieczyszczającymi wody portowe są głównie substancje ropopochodne. Ich rozlewy powstawały najczęściej w wyniku awarii, nieuwagi lub np. zatonięcia statku. W ostatnich latach jednak organizacja HELCOM w roboczych dokumentach pt.: „Draft Report on potentialsources of nutrientinputs: Baltic Sea portshandlingfertilizers” (HOD 52-2017) oraz „Results of the questionnaire on fertilizer cargo handling in Baltic Sea ports” (MARITIME 18-2018) zwraca uwagę na przeładunek substancji sypkich, takich jak nawozy, czy pasze dla zwierząt. Straty podczas ich załadunku/rozładunku i składowania, mycia ładowni, a także niewłaściwego zarządzania wodą opadową powoduje, iż istotny ładunek substancji organicznej, fosforu i azotu trafia do wód portowych. Co istotne ilość substancji nawozowych przeładowywanych w portach Morza Bałtyckiego stale rośnie (od ok 33 milionów ton w 2013 r. do ok. 45 milionów ton w 2015 r.). Wychodząc naprzeciw wyzwaniom polityki środowiskowej związanej z koniecznością monitoringu i ograniczenia emisji substancji biogennych do wód Morza Bałtyckiego, w Katedrze Technologii Wody i Ścieków, na wydziale Inżynierii Lądowej i Środowiska Politechniki Gdańskiej, w ramach Programu „Interreg Południowy Bałtyk”, realizowany jest projekt „Water Innovation System Amplifier” (WISA) - „Innowacyjne zielone technologie wspomagające gospodarkę wodami opadowymi”, 2019 – 2022 (STHB.02.02.00-SE-0153/18). Jego głównym celem jest opracowanie i wdrożenie technologii ograniczających emisję związków biogennych i innych zanieczyszczeń z obszarów portowych do przybrzeżnych wód Morza Bałtyckiego. Liderem projektu WISA jest Krinova AB z siedzibą w Kristianstad w Szwecji, a partnerami, poza Politechniką Gdańską, Uniwersytet w Kłąjpedzie, Port w Gdyni, Port w Åhus, oraz Gmina Hässleholm. Do współpracy w projekcie WISA zostali zaproszeni także lokalni przedsiębiorcy oraz organizacje pozarządowe, które mogłyby być zainteresowane wdrożeniem innowacyjnych narzędzi gospodarowania wodami opadowymi, zarówno w zakresie ich oczyszczania jak i możliwości ich ponownego wykorzystania.

  • Substrate Dependence in the Formation of Au Nanoislands for Plasmonic Platform Application
    • Marcin Łapiński
    • Robert Kozioł
    • Anita Cymann
    • Wojciech Sadowski
    • Barbara Kościelska
    2020 Pełny tekst PLASMONICS

    In this work, the influence of the various substrates on Au nanoisland formation has been studied. Nanostructures were obtained via annealing of thin Au films. In order to determine nanoisland formation mechanisms, correlation between an initial film thickness and temperature of formation, shapes, and dimensions of nanostructures was examined. For the surface morphology studies, nanograin structure, and chemical composition analysis, SEM, HR TEM, and EDS measurements were performed, respectively. Morphology studies showed that the temperature at which nanostructures form varies for different substrates, which indicates high impact of the substrate material on the nanostructure formation. In the case of silicon substrate, besides the phenomenon of spinodal dewetting, the effect of eutectics on the nanostructures was additionally taken into consideration.

  • Sugar matters: sugar moieties as reactivity-tuning factors in quercetin O-glycosides
    • Cezara Zagrean-Tuza
    • Augusitn Mot
    • Tomasz Chmiel
    • Attila Bende
    • Ioan Turcu
    2020 Pełny tekst Food & Function

    Quercetin, one of the most abundant flavonoids in plant-based foods, commonly occurs in nature in various glycosylated forms. There is still a less explored aspect regarding the cause of its glycosides diversity, depending on the sugars moiety attached. This work focuses on four widespread quercetin glycosides—hyperoside, isoquercitrin, quercitrin and rutin—by testing property-tuning capacity of different sugar moieties and thus explain and predict some of their functions in plant-based food. Electron paramagnetic spectra of the semiquinone anion radicals of these glycosides were interpreted in terms of hyperfine coupling constants and linewidths, highlighting a clear link between spin density trends, the identity of the bound sugar, as well as their reactivity corroborated with their modelled structures. Redox potential and lipophilicity were connected to a specific flavonoid-enzyme interaction and correlated with their prooxidant reactivity assessed by oxidation of ferrous hemoglobin. Hyperoside and isoquercitin—galactose and glucose glycosides—exhibit the highest prooxidant reactivity owing to their lowest redox potential and lipophilicity whereas rutin and quercitrin—rutinose and rhamnose glycosides—behave vice versa. The ability of the tested glycosides to undergo HAT or SET-type reactions has also been tested using five different analytical assays, including inhibition of cytochrome ctriggered liposome peroxidation. In most cases, rutin proved to be the most unreactive of all four tested glycosides considering either steric or redox reasons whereas the reactivity hierarchy of the other three glycosides were rather assay dependent.

  • Superconductivity in Metal-Rich Chalcogenide Ta2Se
    • Xin Gui
    • Karolina Górnicka
    • Qiang Chen
    • Haidong Zhou
    • Tomasz Klimczuk
    • Weiwei Xie
    2020 INORGANIC CHEMISTRY

    The metal–metal bond in metal-rich chalcogenide is known to exhibit various structures and interesting physical properties. Ta2Se can be obtained by both arc-melting and solid-state pellet methods. Ta2Se crystallizes a layered tetragonal structure with space group P4/nmm (No. 129; Pearson symbol tP6). Each unit cell consists of four layers of body-centered close-packing Ta atoms sandwiched between two square nets of Se atoms, forming the Se–Ta–Ta–Ta–Ta–Se networks. Herein, we present magnetic susceptibility, resistivity, and heat capacity measurements on Ta2Se, which together indicate bulk superconductivity with Tc = 3.8(1) K. According to first-principles calculations, the d orbitals in Ta atoms dominate the Fermi level in Ta2Se. The flat bands at the Γ point in the Brillouin zone yield the van Hove singularities in the density of states around the Fermi level, which is intensified by introducing a spin–orbit coupling effect, and thus could be critical for the superconductivity in Ta2Se. The physical properties, especially superconductivity, are completely different from those of Ta-rich alloys or transition-metal dichalcogenide TaSe2.

  • Superconductivity on a Bi Square Net in LiBi
    • Karolina Górnicka
    • Sylwia Gutowska
    • Michał Winiarski
    • Bartlomiej Wiendlocha
    • Weiwei Xie
    • R.j. Cava
    • Tomasz Klimczuk
    2020 Pełny tekst CHEMISTRY OF MATERIALS

    We present the crystallographic analysis, superconducting characterization and theoretical modeling of LiBi, that contains the lightest and the heaviest nonradioactive metal. The compound crystallizes in a tetragonal (CuAu-type) crystal structure with Bi square nets separated by Li planes (parameters a = 3.3636(1)Å and c = 4.2459(2) Å, c/a = 1.26). Superconducting state was studied in detail by magnetic susceptibility and heat capacity measurements. The results reveal that LiBi is a moderately coupled type-I superconductor (λe‑p = 0.66) with Tc = 2.48 K and a thermodynamic critical field Hc(0) = 157 Oe. Theoretical studies show that bismuth square net is responsible for superconductivity in this compound, but the coupling between the Li planes and Bi planes makes a significant contribution to the superconductivity.

  • Super-resolved Thermal Imagery for High-accuracy Facial Areas Detection and Analysis
    • Alicja Kwaśniewska
    • Jacek Rumiński
    • Maciej Szankin
    • Mariusz Kaczmarek
    2020 Pełny tekst ENGINEERING APPLICATIONS OF ARTIFICIAL INTELLIGENCE

    In this study, we evaluate various Convolutional Neural Networks based Super-Resolution (SR) models to improve facial areas detection in thermal images. In particular, we analyze the influence of selected spatiotemporal properties of thermal image sequences on detection accuracy. For this purpose, a thermal face database was acquired for 40 volunteers. Contrary to most of existing thermal databases of faces, we publish our dataset in a raw, original format (14-bit depth) to preserve all important details. In our experiments, we utilize two metrics usually used for image enhancement evaluation: Peak-Signal-to-Noise Ratio (PSNR) and Structural Similarity Index Metric (SSIM). In addition, we present how to design a SR network with a widened receptive field to mitigate the problem of contextual information being spread over larger image regions due to the heat flow in thermal images. Finally, we determine whether there is a relation between achieved PSNR and accuracy of facial areas detection that can be analyzed for vital signs extraction (e.g. nostril region). The performed evaluation showed that PSNR can be improved even by 60\% if full bit depth resolution data is used instead of 8 bits. Also, we showed that the application of image enhancement solution is necessary for low resolution images to achieve a satisfactory accuracy of object detection.

  • Supervisory fuzzy control system for biological processes in sequencing wastewater batch reactor
    • Robert Piotrowski
    2020 Urban Water Journal

    The paper proposes the design of the supervisory heuristic fuzzy control system applied to a Sequencing Batch Reactor (SBR) in the Wastewater Treatment Plant (WWTP). Based on real data records and the biological process and aeration system models, a control system for biological processes has been designed. The supervisory control system performs management of the reactor work cycle, determines the phase length, controls the sludge age, calculates the setpoint of dissolved oxygen, and adapts parameters of the lower control layer. The results of simulation tests for the case study wastewater treatment plant are presented.

  • Supporting study tours in the teaching of architectural heritage
    • Michał Kwasek
    • Aleksander Piwek
    2020 Pełny tekst World Transactions on Engineering and Technology Education

    Study tours are a highly effective way to acquire knowledge. They improve students’ understanding of issues that otherwise may seem partly abstract to them. Presented in this article is the unique way in Poland in which support is given to the teaching of architectural heritage. It has been carried out continuously for almost 50 years in the Faculty of Architecture at Gdańsk University of Technology (FA-UT), Gdańsk, Poland, in co-operation with the staff and the Students’ Tourist Association (TXA), which also organises scientific trips. Knowledge of historical architecture provides students with a link to contemporary architecture. Study tours enable students to benefit from direct contact with historic buildings; thus they become aware of the scale as well as the nature of them. This improves students’ understanding of the theory. For the teacher, the study tour is an attractive teaching model. Demonstrated in this article are the advantages of the study tours, their impact on education and their potentialities.

  • Suppression of Supply Current Harmonics of 18-Pulse Diode Rectifier by Series Active Power Filter with LC Coupling
    • Wojciech Śleszyński
    • Artur Cichowski
    • Piotr Mysiak
    2020 Pełny tekst ENERGIES

    The reported research aims at improving the quality of three-phase rectifier supply currents. An effective method consists of adding properly formed booster voltages to the fundamental supply voltages using a series active filter. In the proposed solution, the booster voltages are generated by three single-phase systems consisting of inverters, LC filters, and single-phase transformers. The application of LC couplings ensures low emission of disturbances, but may provoke compensator stability problems. The article presents the current control system for a series active filter designed to suppress the dominant harmonics in the supply currents of an 18-pulse rectifier, without interference into fundamental current components. A proportional control is proposed in combination with integral terms implemented in the orthogonal coordinate systems, which synchronically rotate with frequencies equal to those of the harmonic components to be eliminated. The use of complex gains in integral terms allows a simple phase correction of the output signals. A description is given of the method to determine controller parameters based on the mathematical model of the control object. Sample results of experimental tests performed in steady-state and transient conditions are included to illustrate the quality of performance of the series active filter as compared to the results recorded for the rectifier alone, and for the rectifier with additional line reactor. The applied control method of active filter significantly reduces harmonic distortion of the grid current, which is particularly advantageous at nonideal supply voltage and low loads.

  • Surface and Corrosion Properties of AA6063-T5 Aluminium Alloy in Molybdate-containing Sodium Chloride Solutions
    • Dmitry Kharitonov
    • Illia Dobryden
    • Birhan Sefer
    • Jacek Ryl
    • Angelika Wrzesińska
    • Irina Makarova
    • Izabela Bobowska
    • Irina Kurilo
    • Per Claesson
    2020 Pełny tekst CORROSION SCIENCE

    Corrosion properties of aluminium alloy AA6063-T5 were investigated in molybdate-containing NaCl solutions. Electrochemical, microscopic, and spectroscopic experiments were utilized to examine the mechanism of corrosion inhibition by molybdates. SEM-EDX, magnetic force, and intermodulation electrostatic force microscopy data suggested that the inhibition initiation preferentially occurred over Fe-rich cathodic IMPs. Spectroscopic measurements demonstrated that the formed surface layer consists of mixed Mo(VI, V, IV) species. This layer provided inhibition with an efficiency of ∼90% after 4 h of exposure. High efficacy of ∼70% was achieved even after one week of exposure. A two-step oxidation-reduction mechanism of corrosion inhibition by aqueous molybdates was proposed

  • Surface diffusion and cluster formation of gold on the silicon (111)
    • Walery Pleczysty
    • Ihor Shtablavyi
    • Kamil Rybacki
    • Szymon Winczewski
    • Stepan Mudry
    • Jarosław Rybicki
    2020 Pełny tekst Journal of Achievements in Materials and Manufacturing Engineering

    Purpose: Investigation of the gold atoms behaviour on the surface of silicon by molecular dynamics simulation method. The studies were performed for the case of one, two and four atoms, as well as incomplete and complete filling of gold atoms on the silicon surface. Design/methodology/approach: Investigations were performed by the method of molecular dynamics simulation using the Large-scale Atomic/Molecular Massively Parallel Simulator (LAMMPS). MEAM potential of interatomic interaction was used for modelling. Molecular dynamic simulations were carried out in isothermal-isobaric ensemble (NpT) with a timestep 1.0 fs. Findings: As a result of studies, the preferred interaction between gold atoms and the formation of clusters at temperatures up to 800 K was revealed. Analysis of the temperature dependences of the number of large jumps of atoms made it possible to calculate the activation energy of a single jump. It was found that activation energy of single atomic displacement decreases with increasing number of gold atoms. Research limitations/implications: Only a limited number of sets of atoms were used in the study. It is possible that for another combination of atoms and a larger substrate surface, the formation of gold nanoislands on the silicon surface can be observed, which requires further research. Practical implications: The research results can be used to select the modes of gold sputtering to create gold nanoislands or nanopillars on the silicon surface. Originality/value: Computer modelling of the behaviour of gold atoms on the surface of silicon with the possibility of their self-organization and cluster formation was performed for the first time.

  • Surface effects of network materials based on strain gradient homogenized media
    • Yosra Rahali
    • Victor Eremeev
    • Jean-François Ganghoffer
    2020 Pełny tekst MATHEMATICS AND MECHANICS OF SOLIDS

    The asymptotic homogenization of periodic network materials modeled as beam networks is pursued in this contribution, accounting for surface effects arising from the presence of a thin coating on the surface of the structural beam elements of the network. Cauchy and second gradient effective continua are considered and enhanced by the consideration of surface effects. The asymptotic homogenization technique is here extended to account for the additional surface properties, which emerge in the asymptotic expansion of the effective stress and hyperstress tensors versus the small scale parameters and the additional small parameters related to surface effects. Based on the elaboration of small dimensionless parameters of geometrical or mechanical nature reflecting the different length scales, we construct different models in which the importance of surface effects is dictated by specific choice of the scaling relations between the introduced small parameters. The effective moduli reflect the introduced surface properties. We show in particular that surface effects may become dominant for specific choices of the scaling laws of the introduced small parameters. Examples of networks are given for each class of the considered effective constitutive models to illustrate the proposed general framework.

  • Surrogate modeling of impedance matching transformers by means of variable‐fidelity electromagnetic simulations and nested cokriging
    • Anna Pietrenko-Dąbrowska
    • Sławomir Kozieł
    2020 Pełny tekst INTERNATIONAL JOURNAL OF RF AND MICROWAVE COMPUTER-AIDED ENGINEERING

    Accurate performance evaluation of microwave components can be carried out using full‐wave electromagnetic (EM) simulation tools, routinely employed for circuit verification but also in the design process itself. Unfortunately, the computational cost of EM‐driven design may be high. This is especially pertinent to tasks entailing considerable number of simulations (eg, parametric optimization, statistical analysis). A possible way of alleviating these difficulties is utilization of fast replacement models, also referred to as surrogates. Notwithstanding, conventional modeling methods exhibit serious limitations when it comes to handling microwave components. The principal challenges include large number of geometry and material parameters, highly nonlinear characteristics, as well as the necessity of covering wide ranges of operating conditions. The latter is mandatory from the point of view of the surrogate model utility. This article presents a novel modeling approach that incorporates variable‐fidelity EM simulations into the recently reported nested kriging framework. A combination of domain confinement due to nested kriging, and low‐/high‐fidelity EM data blending through cokriging, enables the construction of reliable surrogates at a fraction of cost required by single‐fidelity nested kriging. Our technique is validated using a three‐section miniaturized impedance matching transformer with its surrogate model rendered over wide range of operating frequencies. Comprehensive benchmarking demonstrates superiority of the proposed method over both conventional models and nested kriging.

  • Survey of Methodologies, Approaches, and Challenges in Parallel Programming Using High-Performance Computing Systems
    • Paweł Czarnul
    • Jerzy Proficz
    • Krzysztof Drypczewski
    2020 Pełny tekst Scientific Programming

    This paper provides a review of contemporary methodologies and APIs for parallel programming, with representative technologies selected in terms of target system type (shared memory, distributed, and hybrid), communication patterns (one-sided and two-sided), and programming abstraction level. We analyze representatives in terms of many aspects including programming model, languages, supported platforms, license, optimization goals, ease of programming, debugging, deployment, portability, level of parallelism, constructs enabling parallelism and synchronization, features introduced in recent versions indicating trends, support for hybridity in parallel execution, and disadvantages. Such detailed analysis has led us to the identification of trends in high-performance computing and of the challenges to be addressed in the near future. It can help to shape future versions of programming standards, select technologies best matching programmers’ needs, and avoid potential difficulties while using high-performance computing systems.

  • Sustainability of Cluster Organizations as Open Innovation Intermediaries
    • Anna Lis
    • Marita Mcphillips
    • Adrian Lis
    2020 Pełny tekst Sustainability

    The purpose of the paper is to identify the most important open innovation practices used by cluster organizations (COs). To reflect these practices, the paper uses the concept of the trajectory of relationship development in COs, applied in the Interizon cluster organization. Additionally, this paper introduces the potential sustainability-related implications of open innovation adoption in cluster organizations. An in-depth direct interview and secondary data analysis were the basic techniques used for data collection. The study demonstrates that cluster organizations can play the role of open innovation intermediaries, implementing a set of different open innovation practices, depending on the level of advancement of cluster cooperation. The use of these practices leads to the development of ever stronger relationships between cluster members, thus conditioning access to the increasingly valuable resources of information and knowledge which are most relevant for the future sustainability-pursuing context. The good effects of multidimensional cooperation in the studied cluster organization prompted the authors to formulate a recommendation for sustainable diversity in the CO. The research goes beyond the state-of-the-art knowledge in the concept of industrial clusters by exposing a broader view on cooperation developed within cluster organizations. The study links the issue of clustering with the concept of open innovation, shedding new light on the processes of supporting knowledge and information flows in COs. Additionally, it contributes to developing a broader comprehension of the context dependencies of open innovation for potential sustainable innovation.

  • Sustainable energy system combined biogas-feedSolid Oxide Fuel Cell and Microalgae technology
    • Araceli Fuerte
    • Rita Ximena Valenzuela
    • Paloma Ferreira-Aparicio
    • B. Bochentyn
    2020 Pełny tekst

    In the new frontier of energy and environmental safety, new efficient and clean safe energy conversion systems are required. In this sense, the present work is framed within the context of Circular Economy and proposes a multidisciplinary study for the development of more efficient, economically viable and non-polluting energy conversion systems, based on the synergetic combination of different technologies: fuel cells, biofuels, CO2 capture, and the use of solar energy and microalgae. In a first step, a doped cerium oxide (Rh/Cu-CeCa) was evaluated as SOFC anode at 1023 K and using H2 and biogas from different sources (algal biogas and landfill biogas) as fuel. Achieved maximum power density for the single cell running on algal biogas was 80 % higher than that obtained with landfill biogas. The comparative study shows the benefits of algal biogas as fuel for SOFC and clean energy production.

  • Synergistic effect of MWCNTs and MA-g-PP on the thermal and viscoelastic properties of immiscible PTT/PP blends
    • Ajitha Anthickamalil Ramachandran
    • Arunima Reghunadhan
    • Aswathi Madathinal Kunjappan
    • Lovely P. Mathew
    • Sabu Thomas
    • David Laroze
    • Michał Strankowski
    2020 NEW JOURNAL OF CHEMISTRY

    The properties of immiscible blends of PTT and PP were modified by grafting and nanoparticle inclusion. The observed synergistic effect of MWCNTs and MA-g-PP on the thermal and viscoelastic properties of PTT/PP blends was studied in detail and the properties of the composites were compared with those of ungrafted PP.

  • Synergistic effect of TiO2 photocatalytic advanced oxidation processes in the treatment of refinery effluents
    • Andre Fernandes
    • Patrycja Makoś
    • Zhaohui Wang
    • Grzegorz Boczkaj
    2020 Pełny tekst CHEMICAL ENGINEERING JOURNAL

    Different types of photolytic and photocatalytic advanced oxidation processes (AOPs) were used for treatment of refinery effluents from bitumen production. The treatment efficiency was evaluated by analyzing chemical oxygen demand (COD), biological oxygen demand (BOD5), volatile organic compounds (VOCs) and sulfide ions concentration. The studies revealed a synergistic effect of application of external oxidants (O3, H2O2, O3/H2O2) with TiO2 and UV applied for improved COD and BOD5 reduction as well as the degradation of the VOCs present in the effluents. Among studied processes a photocatalytic process combined with peroxone (TiO2/UV/O3/H2O2) was the optimal and the most economical technology. It allows to reduce 38 and 32% of COD and BOD5 respectively and degrade 84% of total VOCs in 280 min of treatment. At this conditions the reduced COD exceeds over 30% a theoretical value based on the dose of oxidants, which proves the importance of photocatalysis in the developed technology. The sulfide ions were completely depleted in all experiments in the first 30 min of treatment. The addition of TiO2 in the AOPs technology revealed a decrease in the process cost using less amount of chemicals achieving similar treatment efficiency when comparing with photolytic and non-catalytic technologies. The application of these technologies can be conducted in two alternative scenarios; whether to deplete the sulfides ions concentration or to maximize the treatment efficiency. In both options, the technologies studied are promising as a pre-treatment before other types of AOPs effective at neutral/acidic pH values or before a biological treatment stage. Further studies should be developed, by scaling up the process to a pilot scale in a real case scenario to check the possibility of its implementation in the industrial practice.

  • Synergy between AgInS2 quantum dots and ZnO nanopyramids for photocatalytic hydrogen evolution and phenol degradation
    • María C. Nevárez Martínez
    • Beata Bajorowicz
    • Tomasz Klimczuk
    • Andrzej Żak
    • Justyna Łuczak
    • Wojciech Lisowski
    • Adriana Zaleska-Medynska
    2020 JOURNAL OF HAZARDOUS MATERIALS

    Despite the unique properties of single semiconductor nanomaterials and quantum dots, poor photocatalytic activity has characterized them and the fabrication of nanocomposites has become necessary to enhance their photocatalytic performance. Thus, AgInS2 quantum dots (AIS QDs, 4.0±1.6 nm), have been successfully prepared and loaded onto ZnO nanopyramids (ZnO NPy). The effect of the nominal amount of AIS QDs decorating ZnO NPy on the morphology, optical properties, structure and surface chemistry of the nanocomposites was systematically studied. Photocatalytic tests revealed that the 1%AIS@ZnO NPy sample reported the highest photoactivity for phenol degradation in aqueous phase (92 % after one hour of irradiation, λ>350 nm) that was 4 and 68 times the reported for bare ZnO NPy and AIS QDs, respectively. Accordingly, the maximum photocatalytic hydrogen evolution, under UV–vis light, for the same sample corresponded to 17 and 21 times the estimated for pristine ZnO NPy and AIS QDs, respectively. Hence, the AIS QDs – ZnO system has been applied in the photocatalytic field for the first time in this work and a synergetic effect was confirmed owing to a strong heterojunction formation between both semiconductors that allows an enhanced charge carrier separation, improving the photocatalytic activity.

  • Synteza, struktura chemiczna i właściwości termoplastycznych bio-poli(etero-uretanów) syntezowanych z surowców pochodzenia roślinnego.
    • Paulina Kasprzyk
    2020 Pełny tekst

    Przeprowadzone studia literaturowe, zaprezentowane w części teoretycznej dysertacji, umożliwiły wskazanie głównego kierunku badawczego w ramach studiów doktoranckich. Zaplanowane badania miały na celu opracowanie syntezy oraz zbadanie struktury chemicznej i właściwości nowych termoplastycznych bio-poli(etero-uretanów) (TPUs) otrzymywanych z zastosowaniem monomerów pochodzenia roślinnego. Zrealizowane badania zostały podzielone na trzy główne etapy. Pierwszy z nich polegał na syntezie TPUs z zastosowaniem jednego monomeru pochodzenia roślinnego, którym był bio-glikol. W kolejnym etapie do struktury TPUs wprowadzono bio-poliol. Ostatni etap polegał na modyfikacji triizocyjanianu, w celu otrzymania monomeru dwufunkcyjnego, który lepiej nadawał się do syntezy TPUs. W pracy wykonano także syntezy TPUs z monomerów petrochemicznych w celu otrzymania próbek referencyjnych. Wszystkie TPUs były otrzymywane metodą dwu-etapową. W badaniach otrzymanych materiałów wykorzystano spektroskopię w podczerwieni z transformacją Fouriera, magnetyczny rezonans jądrowy, skaningową kalorymetrię różnicową, dyfrakcję rentgenowską, analizę termiczną dynamicznych właściwości mechanicznych, analizę termograwimetryczną oraz pomiar właściwości wytrzymałościowych w warunkach statycznych. Zbadano przetwarzalność TPUs poprzez pomiary wskaźnika szybkości płynięcia. W rezultacie przeprowadzonych badań wykazano, że możliwe jest TPUs z wykorzystaniem monomerów pochodzenia roślinnego o właściwościach porównywalnych, a nawet lepszych do TPUs syntezowanych w 100% z pochodnych ropy naftowej.

  • Synteza, właściwości i struktura wybranych pochodnych tiomocznika oraz ich związków kompleksowych z kationami metali o konfiguracji d10
    • Damian Rosiak
    2020 Pełny tekst

    Przedstawiona rozprawa doktorska poświęcona jest 1-benzoilotiomocznikom i produktom ich reakcji z halogenkami metali o konfiguracji elektronowej d10 (miedziowce na +1 stopniu utlenienia i cynkowce na +2 stopniu utlenienia) ze szczególnym nastawieniem na ich związki kompleksowe. Istota i cel takich badań przedstawione są we wstępie pracy. Na początku części teoretyczno-literaturowej opisane zostały pochodne tiomocznika ze szczególnym uwzględnieniem 1-acylotiomoczników. Następnie scharakteryzowane zostały metale tworzące kationy o konfiguracji elektronowej d10, które wykorzystano do syntezy połączeń kompleksowych. W dalszej części opisano, czym są związki kompleksowe oraz przedstawiono ich podział ze względu na wymiarowość oddziaływań oraz geometrię ich centrów koordynacyjnych. Omówiono także motywy strukturalne tworzone przez związki kompleksowe 1-acylotiomoczników z miedziowcami i cynkowcami. Zakończeniem tej części jest opis oddziaływań występujących w przedstawianych w dalszej części strukturach krystalicznych i zestawienie stosowanych parametrów. Następnym rozdziałem jest część eksperymentalna, w której przedstawiono techniki badawcze, oraz opisy syntez 1-benzoilotiomoczników i ich związków kompleksowych z halogenkami miedziowców i cynkowców. Kolejny rozdział zawiera opis otrzymanych 1-benzoilo-tiomoczników, związków kompleksowych oraz produktów reakcji pobocznych. Zsyntezowanie dużej liczby ligandów o różnym rozmieszczeniu podstawników oraz użycie różnych halogenków metali pozwoliło na otrzymanie szerokiej gamy związków kompleksowych, co z kolei dało możliwość prowadzenia dyskusji na temat wpływu części organicznej oraz nieorganicznej na ich finalną strukturę. Na zakończenie podjęta została dyskusja wyników i analiza porównawcza otrzymanych związków. Najważniejsze wnioski płynące z zaprezentowanego materiału badawczego zebrane zostały w odrębnym rozdziale. Do pracy dołączone są trzy załączniki – pierwszy stanowią parametry krystalograficzne omawianych związków, drugi – parametry wiązań wodorowych, a trzeci – podsumowanie działalności naukowej i dydaktycznej. Pracę kończy bibliografia. Wykaz wszystkich zsyntezowanych i omówionych związków znajduje się na stronach dołączonych do pracy.

  • Synthesis and Cholinesterase Inhibitory Activity of N-Phosphorylated /N-Tiophosphorylated Tacrine
    • Maja Przybyłowska
    • Iwona Inkielewicz-Stępniak
    • Szymon Kowalski
    • Krystyna Dzierzbicka
    • Sebastian Demkowicz
    • Mateusz Daśko
    2020 Medicinal Chemistry

    Novel phosphorus and thiophosphorus tacrine derivatives were designed, synthesized and their biological activity and molecular modeling was investigated as a new potential anti-Alzheimer's disease (AD) agents. All new synthesized compound exhibited lower toxicity against neuroblastoma cell line (SH-SY5Y) in comparison with tacrine. Two analogues in the series, 7 and 9, demonstrated lack of cytotoxicity against hepatocellular cells (hepG2).

  • Synthesis and hydrogen evolving catalysis of a panchromatic photochemical molecular device
    • Johannes Habermehl
    • Nauroozi Djawed
    • Miłosz Martynow
    • Yury E. Vilk
    • Beranek Radim
    • Julien Guthmuller
    • Rau Sven
    2020 Sustainable Energy & Fuels

    A dinuclear hydrogen evolution photocatalyst [(tbbpy)2Os(tpphz)PtI2](PF6)2 (tbbpy = 4,4′-tert-butyl-2,2′-bipyridine; tpphz = tetrapyrido[3,2-a:2′,3′-c:2′′,3′′-h:2′′′,3′′′-j]phenazine) is synthesized in order to make use of the broader range of visible light absorption mitigated by the osmium center. In a first step, the activity of the complex for hydrogen evolution is investigated by evaluating the role of different electron donors (triethylamine (TEA), 1-benzyl-1,4-dihydronicotinamide (BNAH) and 1,3-dimethyl-2-phenyl-2,3-dihydro-1H-benzo[d]-imidazole (BIH)). The highest photocatalytic activity (TON(H2) of 59) was observed for BIH as the electron donor. UV-vis investigations during catalysis with 470 nm (LED) irradiation show the rise of an absorption band at around 600 nm during catalysis, which indicates the reduction of the bridging ligand. Interestingly, broadband light excitation with wavelengths >450 nm induces no catalytic behavior. An intra-ligand charge transfer transition within the reduced tpphz moiety is hypothesized in order to rationalize the breakdown of the catalysis by broad band excitation.

  • Synthesis of CoFe2O4 Nanoparticles: The Effect of Ionic Strength, Concentration, and Precursor Type on Morphology and Magnetic Properties
    • Izabela Malinowska
    • Zuzanna Ryżyńska
    • Eryka Mrotek
    • Tomasz Klimczuk
    • Anna Zielińska-Jurek
    2020 Pełny tekst Journal of Nanomaterials

    The present study highlights the effect of metal precursor types (SO4 2¯, Cl¯, and NO3¯), their concentration, and the influence of ionic strength of reaction environment on the morphology, surface, and magnetic properties of CoFe2O4 particles. The magnetic nanoparticles were obtained by chemical coprecipitation in alkaline medium at increasing metal concentration in the range of 0.0425 mol·dm-3 to 0.17 mol·dm-3 and calcination temperature from 400°C to 800°C. It was found that the chemistry of precursors can be directly correlated with magnetic properties. The CoFe2O4 particles from metal sulphate precursors showed the highest saturation magnetization and the lowest coercivity. The adjustment of ionic strength in the range of 1.25–5M was achieved by adding an appropriate quantity of metal sulphates into aqueous solutions at a constant pH or by adding an appropriate quantity of NaClO5 under similar conditions. The average hydrodynamic size of CoFe2O4 increased from 46nm to 54 nm with increasing metal concentration and ionic strength. An explanation of magnetic properties, caused by ionic strength and metal concentration, is given based mainly on the reduction in repulsive forces at the particle interface and compensation of the double electric layer in the presence of anions. The observed coercivity was lower for the particles obtained in solutions with the highest ionic strength, whereas the concentration of metals and calcination temperature affected the saturation magnetization and morphology of the obtained cobalt ferrite particles.